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Full text of "Practical Wireless 1971 December"


10 COMPONENTS DICTIONARY 

* /^ SUPPLEMENT 



^fcund Shorty 




A I On - 4-20V REGULATED POWER 



TRANSISTOR TAPE RECORDER 



ADGOLA Soldering 
Instruments add to 
your efficiency 

I THE IMEW'INVADER' 



ADCOLA L.646 

for Factory Bench 
Line Assembly 

A precision instrument — supplied 

with standard 3/16" (4.75 mm) 

diameter, detachable copper 

chisel-face bit*. 

Standard temp. 360 c at 23 

watts. 

Special temps, from 250 c — 

410"c. 

♦Additional Stock Bits 

(illustrated) available 
COPPER 



PRICE 
£1.85 



:= =; 




B 58 -t — 63* 

LONG LIFE 



J> 



B 42 LL A — « « *.». 



BM LL i " - a, 



CHISEl (AC! 



CHIStl FACE 



Don't take chances. We don't. 
All our ADCOLA Soldering 
Instruments are of impeccable 
quality. You can depend on 
ADCOLA day after day. That's 
why they're so popular. You get 
consistent good service . . . relia- 
bility . . . from our famous therm- 
ally controlled ADCOLA Element 
and the tough steel construction 
of this ideal production tool. 

Write for 
price list 
and 

catalogue 
ADCOLA PRODUCTS LTD., 

(Dept. M). ADCOLA HOUSE. GAUDEN RD„ LONDON, S.W.4. 
Telephone: 01-622 0291/3 • Telegrams: Soljomt London Telex .Telex: Adcola London 21851 





TV's 



19 NOW £1195 



TWO YEARS' GUARANTEE ALL MODELS 

405/625:19 £25-95 
23 £35-95 

FREE CATALOGUE 
DAILY DEMONSTRATIONS FOR PERSONAL SHOPPERS 





TEAK HI-FI STEREO 
CABINETS £14-95 

Brand new 44" wide x 1 6" deep 
x 1 8" high with legs. A superb 
piece of furniture. Carriage CI. 
WHILE STOCKS LAST. 



HI-FI VALUE 

1. GARRARD SP25 Mk III 

£11-50, p.p. 50p 

2. TEAK PLINTH & T'NTED 

COVER £4-95, p.p. 35p 

3. 9TAHC DIAMOND SONO- 
TONE CARTRIDGE £2 50 

BARGAIN PACKAGE I, 2 & 3 
£17-95, p.p. 85p 




COMPONENTS MUST BE CLEARED 



Transistor Radio Cases: 15p 

each. Size 9±" x 6J-" x 3^-". Post I Sp. 
Speakers: 35p. 2i" Bil. Brand 
new. Post ISp. 

VHF.'FM Tuners: 95p. 88-108 
megs, takes EEC85 valve (extra). 
Post I5p. 

Radio: £3-95 8 transistor LW/ 
MW. Free case, battery. Post I5p. 
Precision Tape Motors: £1 -95. 
200/250V. Famous German manu- 
facturer. Post 20p. 



Transistor Gang Condensers: 
20p. Miniature AM. Post free. 
Modern Gang Condensers: 30p. 
AM/FM or AM only 20p. Post lOp. 
Transistors I5p each. Post free. 
ACI26, ACI28, AFI 14. AFII7. 
OC45, OC7I, OC8I, OC8ID. 
Valve ELL80 50p. Only stock in 
the country. 

Pots.: 25p each. Post 5p. D/SW 
500/500 KQ. D/SW 500/100 KQ. 
D/SW I meg./lOO KQ. S/SW 
5C0/500 KQ. S,SW 500/1 meg. 



DUKE & CO. (LONDON) LTD. 

621,3 ROMFORD ROAD, MANOR PARK, E.I2. Phone 01-478 6001-2-3 




for fast, easy, 
reliable soldering 

Contains 5 cores of non-corrosive 
flux, instantly cleaning heavily 
oxidised surfaces. No extra flux 
required. 



SAVBIT ALLOY 
ALSO REDUCES 
COPPER BIT WEAR. 

Ecomically packed for 

general electrical 
and electronic 
soldering. 75ft. 
18 gauge on 
plastic reel. 
Recommended 
retail price 75p 

Size 12 




A RANGE OF 
SOLDERS IN HANDY 
DISPENSERS. . 

REF. ALLOY SWG 

19A 60/40 18 18p* 
Size 5 

ustra- Savbit 18 18 P* 
ted) 

15 60/40 22 22p* 

"Recommended Price 



THIN GAUGE 
SOLDER, 
ESSENTIAL FOR 

soldering small components 
and thin wires. High tin 
00£l^ content, low 
■^4£fl^ melting point, 
Wk j 60/40 alloy, 170ft. 
SSft ~ 22 gauge on 
plastic reel. 
Recommended 
retail price 75p 
Size 10 




INVALUABLE FOR STRIPPING 
FLEX, THE NEW AUTOMATIC 
OPENING BIB WIRE STRIPPER 
AND CUTTER, easily 

adjustable for all 
standard 

diameters. Plastic 
covered handles 
can also be used 
as wire cutter. 
Recommended 
retail price SOp 




From Electrical and Hardware shops. If unobtainable, write to: 

Multicore Solders Ltd., Hemel Hempstead, Herts. 



HI-PI BARGflin OP THC CCHTUIW 

/live up lo 55% on LEAK recommended li/l price/! 

As the United Kingdom's leading High Fidelity Retailers we are proud to offer you the "Scoop of the 
Century" Leak Hi-Fi Amplifiers, tuners, turntables and speakers at fantastic prices. Each piece of 
equipment is brand new and covered by Leak's full guarantee. Leak have been the U.K.'s leading 
manufacturer since the birth of High Fidelity — their quality has always been used as the yardstick 
for true High Fidelity. 



/ 




Leak Stereo 70 amplifier (cased only)— Power output (both channels linewave driven): 35 watts 
r.m.s. each channel into 3 ohm. loudspeakers. Total harmonic distortion: 01°,', for all power levels 
up to 25 watts r.m.s. each channel at I KHz into 8 ohm loudspeakers. Crosstalk: between left and 
right channels— 50dB up to IKHz and — 30dB at lOKHz. Dimensions: I3in (W.) x 4}in. (H.) X 9|in. 
(D.). LIST PRICE £7500 LASKY'S PRICE £5500. Carriage £100. 

Leak Stereofetic FM tuner:— Frequency range: 87.-l08mHz. Frequency response: ± IdB 40Hz to 
1 5kHz. Frequency drift: Less than 25KHz without A.F.C Sensitivity: 2i microvolts for 3dB signal/ 
noise. Output impedance: 200 ohms. Distortion: less than 0-5% for full deviation, i.e.: less than i°-„ 
for average modulation. Signal/Noise: 60dB A.M. suppression: 50dB. Dimensions (cased) I2in. (W.) * 
4}in. (H.) x 9}in. (D.) chassis I Win. (W.) x 4±in. (H.) x 7|in. (D.) 
CASED LIST PRICE £69 80. LASKY'S PRICE £4500 

CHASSIS LIST PRICE £6403. LASKY'S PRICE £39 50. Carriage £1 00 on chassis or cased 
model. 

Leak Stereo 30 Plus amplifier (cased only) — Power outputs (both channels sinewave driven) 
15 watts r.nu. each channel into 8 ohms loudspeakers. Music power outputs 20 watts r.m.s. each 
channel into 8 ohm loudspeakers. Total Harmonic distortion 01% for all power levels up to 10 watts 
r.m.s. each channel at IKHz into 8 ohm loudspeakers. Crosstalk: between left and right channels, 
— 50dB up to IKHz and — 30dB at lOKHz. Dimensions: I Sin. (W.) ■ 4Jin. (H.) x 9*in. (D.). LIST 
PRICE £62-50 LASKY'S PRICE £45-00. Carriage £1 00. 




Leak Truspeed Transcription Turntable Mk. Ill — 
A low speed (250 r.p.m.) synchronous 12-pole hysterisis 
motor ( 100-1 30V.. or 200-250V.. 1 5 mwA). gives constant 
turntable speed independent of mains voltage fluctu- 
ations. Speeds: 331 r.p.m. and 45 r.p.m. Wow: Less than 
01 5%. Flutter: Less than 002%. Frequency range: 
20Hz-20KHz. Stereo separation: better than 25dB at 
IKHz. Dimensions: I2|in. x ISJin. x 7 T in. inc. cover. 
Complete with arm, teak base and tinted perspex cover 
and Shure M75/6 cartridge. Made to sell for £69-50. 
.LASKY'S PRICE £47 50. Carriage £1-50. 



Leak 200 speaker system — A Stain- 
Mess Steel woven mesh grille cloth 
Ifor maximum acoustic transparency 
land an attractive teak cabinet 
[finished off with aluminium trim all 
| round housed a 3 speaker system 
worthy of LEAK's name. Impe- 
Idance: 8 ohms nominal. Frequency 
I response: 60Hz to ISKHz. Power 
I handling capacity 18 watts r.m.s. 
I Resonance of bass unit (free air): 
|45Hz. Finish: Teak. Dimensions: 
llSiin. x lOin. x 81in. LIST PRICE 
£49-90. LASKY'S PRICE £31-50 
l(pair). Carriage. £200 



fantastic LEAK packages 




Package I 

Stereo 30 Plus (cased) £62-50 

Stereofetic (chassis) ..£6403 

Total Rec. Retail Price £126-53 

LASKY'S PRICE £04. C ft P. £1-50 

Package 2 

Stereo 70 (cased) £75-00 

Stereofetic (chassis) ..£64-03 

Total Rec. Retail Price £139-03 

LASKY'S PRICE »4. C ft P. II -W 

Package A 

LEAK ST 30 Plus (cased) £62-50 

LEAK 200 Spks. (pr.) £49-90 

LEAK Truspeed T/T system ..£69-50 

Total Rec. Retail Price £181 90 

LASKY'S PRICE £120. C. * P. £2-00 

Package B 

LEAK ST 70 (cased) £75-00 

LEAK 200 Spks. (pr.) £49-90 

LEAK Truspeed T/T system ■■£69-50 

Total Rec. Retail Price £194-40 

LASKY'S PRICE £130. C. a P. £200 

Package C 

LEAK ST 30 Plus (cased) £62-50 

LEAK Stereofetic (cased) £69-80 

LEAK 200 Spks. (pr.) £49-90 

LEAK Truspeed T/T system £69-50 

Total Rec. Retail Price £251 -70 

LASKY'S PRICE £160. C. * P. £3-00 

Package D 

LEAK ST 70 (cased) S5'2S 

LEAK Stereofetic (cased) £69-80 

LEAK 200 Spks. (pr.) £49-90 

LEAK Truspeed T/T system £69-50 

Total Rec. Retail Price £04-20 

. LASKY'S PRICE £170. C. * P. £3-00 



Package E 

LEAK ST 30 Plus (cased) £62-50 

Wharfedale Denton Spks. (pr.)... £39-90 

BSR McDonald MP60 £15-20 

Lasky's base and cover £4-75 

AD76K magnetic cartridge ...£4-35 

Total Rec. Retail Price £126-70 

LASKY'S PRICE 192. C. ft P. £2-00 

Package P 

LEAKST70 £75-00 

Wharfedale Triton Spks. (pr.) £59-90 

Garrard AP76 £27>85 

Garrard base and cover £9-75 

Shure N44/E magnetic cartridge. . .£ 1 1 -63 

Total Rec. Retail Price £184-13 

LASKY'S PRICE £129. C. * P. £3-00 

Package G 

LEAKST30 Plus (cased) £62-50 

Lasky's Criterian Mk. X Spks. ...£25-00 

BSR McDonald MP60 £15-20 

Lasky's base and cover £4-75 

AD76K magnetic cartridge ...£4-35 

Total Rec. Retail Price ....: £1 1 1 -80 

LASKY'S PRICE OS. C. * P. £2-00 

Package H 

LEAK ST 70 (cased) £7500 

LEAK Stereofetic (cased) £69-80 

LEAK Truspeed T/T system £69-50 

LEAK 600 spks. (pr.) £9900 

Total Roc. Retail Price £313-30 

LASKY'S PRICE £225. C. & P. £400 

These are only a few of our pack- 
age bargains incorporating LEAK 
equipment, many more can be 
arranged. If none of the packages 
here suit you please send us details 
of your requirements and we will 
be pleased to quote. 



657 



SUPER 



sonv 

SCOOP! 




DIGITAL CLOCK 
RADIO 8FC-S9WA 



SAVE 
£12 19 



Sony's elegantly designed digital alarm clock radio. The digital 
clock shows you the time minute by minute with matchless 
accuracy, and once set the Digimatic will wake you up at the same 
time every morning without having to be re-set. The radio "«'on 
features Sony's unique sleep button, you fall gently to sleep lulled 
by the sweet tone of the radio, which switches itself off at a pre- 
determined time. Available in either black, red or white. Frequency 
range 530-1. 605KHz (AM): 87-I08MHZ (FM). Uses 8 transistors and 
8 semi-conductors, built-in ferrite aerial and 3t loudspeaker. 
Power requirements: 230v AC 50Hz. Dimensions: 121 X Jf x it . 

Post 
25p 



List Price L ASKY'S ,/|#C«TC 
£28 94 PRICE fciW M* 



NEW pom 



Criterion 
MkX 

Because of the increasing 
demand for inexpensive, 
high quality bookshelf 
speakers, we have seen 
fit to introduce the Cri- 
terion Mk. X bookshelf 
system. The speaker is a 
sealed infinite baffle type 
enclosure using Bin. 
woofer, a 5in. mid. range 
and 2^in. tweeter. The 
compact cabinet is 
in oiled walnut and black 
woven speaker grille 
cloth. Frequency res- 
ponse 40Hz — 20KHz. 
Power handling capacity: 
Max. 20 watts. Impe- 
dance: 8 ohms. The Cri- 
terion is fitted with two 
types of speaker lead 
connections — screw ter- 
minal or phono. Size: 
ISJin. (H.) x 9Jin. (W.) 
9Jin. (D.). Operational 
horizontally or vertically. 

LASKY'S 

AMAZING 

PRICE 



la/kys 




Post 50p 



£13-50 each 



OUT HO W! '74 

AUDIO-TROMCJ 



aBMeftWMfrt* 




The great new 1972 edition 
of Lasky's famous Audio- 
Tronics catalogue is now 
available — FREE on re- 
quest. The 44 newspaper 
size pages — many in full 
^"[colour — are packed with 
I j 1 ,000's of items from the 
I I largest stocks in Great 
I J Britain of everything for the 
' I Radio and Hi-Fi enthusiast. 
! Electronics hobbyist. 
Serviceman and Communi- 
cations Ham. Over half 
the pages are devoted 
exclusively to every aspect 
of Hi-Fi (including Lasky's 
budget Stereo Systems and 
Package Deals). Tape 
recording and Audio 
accessories and don't 
miss LASKY'S AUDIO 
TRONICS CREDIT 

CARD SCHEME offering 
holders one months inter- 
est free credit up to £50 
and the fantastic Audio 
Tronics £1.000 -f SONY 
COLOUR TV competition. 



Send your name and 
address and ISp for post 
and inclusion on our regu- 
lar mailing list. 



a m unci future 

Lasky's Radio for over 38 years Great Britain's Leading 
Radio, High Fidelity, Tape Recorder and Electronics 
Specialists have vacancies in their West End and City 
Branches for both male and female Sales Assistants. We 
are seeking intelligent young men and women sales 
personnel to join our expanding organisation (already 
the largest in Europe) on a career basis with the finest 
prospects for early promotion and financial advancement. 
Working with our energetic sales teams in any of our 
six West End and City branches will bring you into 
contact with people from every walk of life including 
Pop Stars, film and television personalities, royalty and 
above all enthusiasts in every field of Audio, Hi-Fi and 
Electronics — people who expect you to share their 
enthusiasm and interest. 

Knowledge of Hi-Fi and electronics is not essential 
although it will help— all that we require as the basic 
qualities needed for a successful application are willing- 
ness to learn and a common sense approach to the 
business of selling. Salary ranges from £850 to £1,850 
plus, three weeks holiday after one year, and Incentive 
Bonus Schemes are added benefits of working in our 
progressive organisation. Holiday arrangements will be 
honoured. If you are interested in a career in Audio and 
Hi-Fi write at once to: — 

Kenneth Lasky, 

Lasky's Radio Limited, 

3-15 Cavell Street, London, E.I 2BN. 

Interviews will be arranged to suit your convenience 



658 



! 



r 



SUPER SPEAKER BARGAINS 

WHARFEDALE DENTONS-=S 



A compact system sold in matched 
pairs for a perfectly balanced 
stereo system. Each Denton con- 
tains an Sin. bass unit with 3in. 
pressure unit, coupled by a 
Wharfedale crossover network. 
Rated input: 15 watts maximum. 
Frequency response: 65-17, 000Hz. 
Impedance: 4/8 ohms. Cabinet 
9}in. x Uin. x 8}in. These most 
attractive units are available in 
oiled teak, and are small enough 
to blend in with most surround- 
ings. 



LIST PRICE 
£39-90 



Post SOp 



£29-00 



WHARFEDALE TRITONS 



A new and exciting addition to the 
Wharfedale range, this three speaker 
system will satisfy the most ardent Hi-Fi 
enthusiast. Shelf or floor standing — hand 
finished in oiled teak. Frequency 
response 55-22, OOOHz. C.A.B. Dome 
pressure unit. Bass unit Sin. Midrange 
unit 5in. Treble unit 2in. impede 
8 ohms. Sixe 2l}ln. x 9jm. x 9in. 

LIST PRICE £5990 

LASKY'S £39*00 n* 
PRICE 




INTERNATIONAL 



Post 50p. 



bsr Mcdonald MP60 

High precision low-mass counterbalanced 
pick-up arm, heavy balanced turntable, 
.imple to operate controls, viscous cueing 
ilevice. slide in cartridge carrier, 4 pole 

LASKY'S PRICE £12'50 Post 35p 

bsr Mcdonald 
units & packages 

A. Chassis only. B. Complete with Lasky's plinth 
ind cover. C. Complete with Lasky's plinth, 
cover and AD76K cartridge. D. Comp. wired on 
BSR plinth with cover. I. As D plus AD76K cartridge. 



MODEL ABB 

MP.60 11-20 IS-50 1900 

HT.70 1590 1000 23 50 

610 14 SO 18 57 3200 

SIO 12-10 16 SO 19 85 

310 9 75 14-00 17 25 
210 
MP.60 TPD2 Styrene base 




D 
19-25 
24-50 

21 00 
20 00 

17 90 

18 00 



E 

2200 
27-00 
25 SO 

22 as 

20-25 
♦ •95 

21 00 



GARRARD UNITS AND 
PACKAGES 

GARRARD SL 55B 

Four speed autochanjer 
LASKY'S X|gf>.m p °" 
PRICE *IO # *W 35p 




Now ava. labia ZERO 
£49.95, post Up. 
Garrard SP2S Mk. Ill 



Garrard SL40B £9-95 

Garrard AP76 without cart. £20-95 

Garrard 3000 with 9TA cart. £10-50 
Garrard 2025TC with 9TA 

cart £9 85 



GARRARD PACKAGES X"...** 

Garrard AP76 with AD76K cart, and Lasky's plinth and cover £35 

Garrard AP76 with Shure M44E cart, and Lasky's plinth and cover ... £40 

Garrard SP25Mk. III. AD76K cart, and Lasky's plinth and cover £20 

Garrard SP25 Mk. III. Micro M2IOO/e cart, and Lasky's plinth and cover £25 



LASKY'S NEW LOW NOISE 
CASSETTES FROM THE USA 

SB 

C-90 
C-120 

Post Each 5p. S-20p. 10-25. 20-50p. 



Si 3fp" 


5 


10 


20 


£1-52 


£2-96 


£5-60 


50p 


£2-37 


£4-62 


£8-75 


69p 


£3-2» 


£6 38 


£1085 



a,dio 



'"?■ BT.20 Message Tape 22Sft. I9p 

Jim. BTJI Triple play. 600ft. 

Mylar SOp 

Sin. RT.23 Double play. 1,200ft. 75p 
Sin. RT.I8 Long play, 900ft 

Acetate SOp 

Sin. RT.I7 Standard play 600ft. 43a 
Sjin. RT. 1 5 Double play. 1,800ft. 

Mylar £|.|3 

Stin. RT.I6 Long play 1.200ft. 

Acetate 75p 

5Jln. RT.24 Standard play 900ft. 

P-V.C. Up 

5*in. RT.I4 Long play 1.200ft. 

Mylar 75p 

1 per reel, 4 reels & over 



1 P. 5p e> 



•f"' SZ-H T ri «» ,e ^"y. 2.4ooft. £i-ii 

7in. RT.22 Standard play, 1,200ft. 

Acetate 6)e> 

7in. RT. 10 Standard play. 1 ,200ft. 

Mylar «Jp 

7in. RT.I2 Long play, 1,600ft. 

Mylar *j p 

7in. RT.I3 Double play, 2,400ft. 

Mylar «!.» 

7in. RT.II Long play. 1.800ft. 

Acetate 75p 

7in. RT.I9 Triple play, 3,600ft. 

Mylar £2-50 

3»in. RT.22Quad play. 1,100ft. £1-02 
Post Free. Special quotes for Quantities 



KATONE AM/AIRCRAFT 
PORTABLE RADIO 

BATTERY/MAINS 

A combined battery and mains portable of excep- 
tionally attractive design. Housed in a leatherette 
covered case, size 8±in. x 5Jin. x 3±in.. fitted with 
an 8-section external telescopic aerial for FM and 
internal ferrite rod for MW wave bands, and clear 
ensy-to-read dial with logging scale. Wave band 
coverage is FM 88- 108MHz. AM 535-1. 600KHz. A 
highly selective circuit using 9 transistors and 9 
aemi-conductors operating from either 4 x 1-5 
volt torch batteries or direct from 230 volts 50Hz 
AC house mains, from a built-in mains unit. A 
socket is fitted for a personal earphone. Easy-to- 
use silver colour knobs, with "woodgrain" panel 
enhances the appearance of this fine radio. 

LASKY'S PRICE £9*9S *. 




DIGITAL CLOCK SCOOP 




EXCLUSIVELY 
FROM LASKY'S 

for you to mount into any housing. 
The clock measures 4» W x I J H x 3J D (overall 
from front of drum to back of switch). SPEC: 
210,240V a.c. 50Hz operation; switch rating 
250V. 3A. Complete with instructions. HUN- 
DREDS OF APPLICATIONS. COMPLETE 
WITH KNOBS. 



• MADE ESPECIALLY 
FOR LASKY'S BY 
FAMOUS MAKER 

• MAINS OPERATION 

• I2-H0UR ALARM 

• AUTO "SLEEP" 
SWITCH 

• HOURS. MINUTES 
AND SECONDS 
READ-OFF 

• FORWARD AND 
BACKWARD TIME 
ADJUSTMENT 

• SILENT OPERATION 
SYNCHRONOUS 
MOTOR 

• SHOCK AND 
VIBRATION PROOF 

B BUILT IN ALARM 

BUZZER 
SPECIAL QUOTES fOR 
QUANTITES 



LASKY'S PRICE £*SO *« 



20p 



TRIO HS.I & HS.2 STEREO HEAD- 
PHONE BARGAINS 

Models HS-I end HS-1. Both these 
sets by TRIO offer really superb stereo 
reproduction in a lightweight, fully 
adjustable headset designed for opti- 
mum comfort. Listening fatigue is 
unknown with TRIO headphones. 
Brief spec, both models: Input imp. 
80 nominal (matching 4 to 8Q); max. 
input 0-5W; frequency response 

20-19 kHz; output sensitivity at I mW input: HS-I II ,^. 

0-66lbs. Identical in appearance— both models are finished in 
creating foam filled ear pads and head band. 
LIST PRICE £8-40 LIST PRICE £6-75 

HS.1 €S HS.2 £4 PMtl8B 



ited 




1 1 1 dB; weight 
vory with eon- 



207 EDOWARE ROAD. LONDON. W.2 Tel: 01-723 3271 
33 TOTTENHAM C i. RD. LONDON. W.l Tel: 01-636 2605 

Open all cloy 9ojti -6p.m Monday IcSolufdoy 

152/3 FLEET STREET. LONDON. E.C4 Tel: 01-353 2833 

Open oil day Thu* sday. eo'ly closing 1 p m Sol wdoy 



The Home ol Wigh fideiily 

1215 TOTTENHAM CI RD.. LONDON. W.l Tel: 01580 2573 

Openolldoy 9am -6pm Monday loSoluidoy 

NEW CITY BRANCH NOW OPEN 

109 FLEET STREET. LONDON. t.CM Tel: 01353 5812 

Open oil day Thundou $>0'ly doting tp m Solu-doy 




ALL MAIL ORDERS AND CORRESPONDENCE TO: 3-15 CAVELl ST. TOWER HAMLETS LONDON. E.I Tel: 01-790 4821 



659 



Another tremendous bargain 
fromJermyn 







£775 complete 



Better spark at all revs. 
Easier cold starting. 
Longer battery life. 
Less wear on points. 
Smoother running. 
Lower petrol consumption. 
Longer plug life. 

Set of parts to enable the 
electronics hobbyist to build 
the Electronic Ignition as 
described in P.W. June '71 . 
Inverter transistors. Diodes, 
Zeners, Resistors, Capacitors, 
Transformer, robust die cast 
box 2 x 34 x 44 ", circuit 
diagram and Free Car Sticker. 



State + or — ve earth and 

^end cheque or P.O. £7.75 
including p. and p. to : - 
Jermyn Industries, 
Vestry Estate, Sevenoaks, Kent. 

JERMYN 

Prompt despatch by post. 



The Unique 

MULTI-MINI 



-VICE 




An extra "Pair of hands" for 
those tricky jobs 

ASSEMBLY— SOLDERING— 

GLUING— WIRING— DRILLING 

ETC. 

• INDEPENDENT ADJUSTMENT OF 
THE TWO VICE HEADS TO ANY 
ANGLE WITH POSITIVE LOCKING. 

• JAWS WILL FIRMLY GRIP. ROUND. 
FLAT. SQUARE, OR HEXAGONAL 
PARTS. 

TWIN VICE: £5.90 (24p P & P) 

ALSO AVAILABLE 

SINGLE VICE: £3.37; (20p P & P) 

COVENTRY MOVEMENT CO LTD. 

Depc. PW3 

BURNSALL ROAD. COVENTRY 

CV5 6BU STD 0203-74363 



H.A.C. 

WORLD-WIDE RECEPTION 



SHORT-WAVE 
KITS 




Famous lor over 35 years for Short-Wave Equip- 
ment o! quality. "H.A.C." were the Original 
suppliers of Short-Wave Receiver Kits tor the 
amateur constructor. Over 10,000 satisfied 
customers — including Technical Colleges, Hos- 
pitals, Public Schools, R.A.F., Army, Hams, etc. 

HEW "DX" RECEIVES 
Improved one-valve model "DX" mark 2. 
Complete kit — price £3.80 (post & packing 20p.). 
Customer writes: "Australia, India and America 
at loud volume." — "1 am 14 years of age and have 
logged over 130 stations, plus counties) Amateurs 
from all over the world." 

Send 8.A.E. for test report. 
This kit contains all genuine short-wave com- 
ponents, drilled chassis, valve, accessories and full 
instructions. Ready to assemble, and of course, 
as all our products — fully guaranteed. Full range 
of other 8.W. kits, Including the famous model 
"K" and "K plus" (Illustrated above}. All orders 
despatched by return. (Mall order only.). Bend 
now for free descriptive catalogue A order form. 

"H.A.C." SHORT-WAVE PRODUCTS 
29 Old Bond Street, London W.I 



The BATTERIES That 
Won't Let You Down! 
RECHARGEABLE 



Cells in U2.U11 
and Penlite 
U7 sizes 
Kestral Battery 
Charging Unit 



Uses : 

Tape recorders, Portable 

radio and TV, Radio c o.Mrolled modal 

aircraft and boats, Cine cameras, Flashgun!, 

Cordless shavers and other battery appliances. 

PRICES 

Batteries Ut 
equlv. £1-25 




Whenever you must have 
utterly dependable battery 
power— then these new 
Alkaline-Manganese re- 
chargeable cells will pro- 
vide It. The cells can be 
recharged many times, a 
simple Job with the Kestrel 
Charging Unit which has 
been specially designed for 
these new type batteries. 



Penlite U7 
equlv. Mp 



Charging 
unit £3'9t 
with one 
battery 
holder 



KESTREL 



8u5k2lMe<Wi 



Send lo: 

27S WEST END LAN! 
LONDON, N.W.s 
01-TS4 9611 



660 



FIND 
BURIED TREASURE! 

TREASURE LOCATOR 
TRANSISTORISED 

HOW IT'S HEBE AT LAST, after experimenting for four and a 
lialf months with a multitude of different circuits and carrying 
out actual field tests with prototypes, our design team have come 
up with this, real winner. This fully portable transistorized metal 
locator detects and tracks down burled metal objects— it signals 
exact loca'ion with loud audible sound (no phones used) — uses 
any transistor radio which fits inside — 
no connections needed. FINDS GOLD, 
SILVER. LOST COINS. JEWELLERY. 
KEYS. WAR SOUVENIRS. ARCHAE- 
OLOGICAL PIECES, METALLIC ORE. 
IttJGGETS ETC. ETC. Outdoors or in- 
Kxtremely tentilive. will signal 
presence of certain object* buried several 
feet below ground ! No knowledge of 
radio or electronics required. Can be 
buiu with tate In one short evening by 
anybody from nine years of age upwards, 
with the wonderfully clear, easy to 
follow, step-by-step, fully illustrated 
Instructions — ft really Is easy as 
A. B.C. transistorized — no 
ONLY valves. Uses standard PP3 
battery. No soldering neces- 
sary. Size of detector head 
18|* x 10- x 2J-. Great 
demand expected at this 
remarkably low price— 
ORDER WHILE PRE- 
SENT STOCKS LAST. 
All parts including de- 
tector head case, nuts, 
screws, wire, simple 
Instructions etc. etc. 
ONLY 42-87 (47/6) + 
27p (6/6) p. & p. 
(Sectional handle as 
Illustrated 75p (15/- 
extra). Parts available 
separately. Made up 
looks worth £15 ! 




Makes Fantastic 
Christmas Gift 



BUILD 5 RADIO AND 
ELECTRONIC 
PROJECTS 

(39/6) 
Amazing Radio Construction 
sett Become a radio expert for 
fl-87 (39/6). A complete 
Home Radio Course. No ex- 
perience needed. Parts includ- 
ing simple Instructions for each 
design. Illustrated 
Step-by-step plans, 
all Transistors, loud- 
speaker, personal 
phone, knobs, screws, etc., all you need. Presentation Box 87p 
(7/6) extra as Illus. (If required) (extra parts available separ- 
ately) no soldering necessary. Send only £1-97 (39/6) + 23p 
(4/6)«>. A p. 




Sp*f&* 



Makas •xcicirif 
Christmas present, 




SOOTHE YOUR NERVES, RELAX WITH 

amazing RELAXATRON 



Ideal 

Christmas 

Gift 



only 

£2-25 

(45/-) 




CUTS OCT NOISE POLLUTION— SOOTHES YOUR NERVES! Don't 
underestimate the uses of this fantastic new design— the RELAXATRON 
is basically a pink noise generator based on avalanche operated transis- 
tors. Besides being able to mask out extraneous unwanted sounds, it has 
other very interesting properties. For instance, many people find a 
rainstorm mysteriously relaxing, a large part of this feeling of well-being 
can be directly traced to the sound of falling raindrops! — a well known 
type of pink noise. A group of Dentists have experimented on patients with 
IkU pink noise— HO ANESTHETICS WEBB USED! The noise ostensibly created a most definite reaction on these patient* 
nervous systems with the results that their pain systems were blocked. IF YOU WORK IN NOISY OR DISTRACTING 
SUF.ROUNDIHGS, IF YOU HAVE TBOUBLE CONCENTRATING, IF YOU FEEL TENSED, UNABLE TO RELAX- 
then build this fantastic Relaxation. Once used you will never want to be witho ut It— u se this amazing pink noise gen- 
erator whenever you feel uneasy, can't relax or wish to concentrate. TAKE IT ANYWHERE, pocket sized. Uses standard 
PP: batteries (current used ao small that battery life la almost shelf-life) CAN BE EASILY BUILT BY ANYONE OVER 
12 YEARS OF AGE using our unique, step-by-step, fully illustated plans. No soldering necessary. All parts Including case, 
a pair of crystal phones. Components, Nuts, Screws, Wire, etc. etc. no soldering. Send only 12-25 + 25p (46/- + 6/-) 
p. & p. parts available separately.) 




GET A GOOD NIGHT'S SLEEP— EVERY NIGHT! 
INGENIOUS ELECTRONIC £"' only 

SLEEP INDUCER °" «2;75 

(55/-) 

CANT 8LEKP AT NIOHTSP DO YOU WAKE UP IN THE NIGHT AND CAN'T GET OFF TO SLEEP AOAINP WOULD 
YOU LIKE TO BE GENTLY SOOTHED OFF TO SATISFYING SLEEP EVERY NIGHT? Then build this ingenious elec- 
tronic sleep Inducer. It even flops by itself so you don't have to worry about it being on all night'. The loudspeaker produces 
soothing audio- frequency sounds, continuously repeated — but as time goes on the sounds gradually become less and lest. 
— until they eventually cease altogether, the effect it has on people is amazingly very similar to hypnosis. A control Is pro- 
vided for adjusting the length of times etc., all transistor, can be built by anyone over 12 years of age In about two hours. 
No knowledge of electronics or radio needed. Extremely simple, easy-to-follow, step-by-step, fully illustrated instruction* 
Included. No soldering necessary. Works off standard batteries — extremely economical. Size only 3" x 41* x If* — take 
It anywhere. All parts Includ ing case, loudspeaker, components, nuts, wire, screws, etc. etc. THERE WILL BE A GREAT 
DEMAND FOB THIS UNIQUE NEW DESIGN— SEND NOW £2-75 + 25p (68/- + 6/-) p. A p. (parts available separately). 



(55/-) 
case, londspeaki 
(bir. full) Instructions, 
yourself, finish with an 



REAL WORKING ELECTRONIC ORGAN 

Don't confuse with ordinary electric organs that simply blow air 

over mouth-organ type reeds etc. Eight months were spent In 

creating and testing this superb, revolutionary electronic 

organ. Fully transistorized — no valves. Proper Mil-contained 

loudspeaker. Fifteen separate keys span two full octaves — play 

the "Fellow Bote of Texas", play "SU-nf Night", play "Auld 

Lang Syne", play lots and lots of similar tunes on this real 

working electronic organ. Although It's no theatre organ ItV 

certainly no tiny thing, it measures 13} x JO x 94*. You have 

the thrill and excitement of building It together with the 

pleasure of playing a real, live, throbbing electronic organ. Tal' 

it anywhere— plav it anywhere, NO PREVIOUS KNOWL EDGE 

OF ELECTBONICS NEEDED— NONE WHATEVER. No 

soldering necessary, it really Is as simple as a.b.c. to make. 

Anyone from nine yean upward! can build it easily in one short evening following t he fu lly Il lustrate d. 

«tep-by-Bt*p, simply worded instructions. BIS DEMAND ANTICIPATED FOB THIS UNIQUE INSTBU- 

■ENT at our low, low building price. ONLY £2-75 (55/-) + 23p (4/6) p. * p. (or all parts, Including 

r. transistors, condensers, resistors, knobs, transformer, volume control, wire, nuts, screws, simple 

■.etc. Uses standard battery (parts available separately). Have all the pleasure of making it 

Itlng gift fori 




Makas a thrilling 
Christmas present 



SHORTWAVE 
TRANSISTOR RADIO 



ONLY 

£2-25 



ONLY 

£2-37 



EAVESDROP ON THE EXCITING WORLD OF 
AIRCRAFT COMMUNICATIONS — JUST OUT 

If II C AIRCRAFT BAND 
w '"' r ' CONVERTER 

Many thousands ol v.h.I. Aircraft Band Converters now 
idling In U.S.A. Listen in to AIRLINES. PRIVATE 
PLANES, JETPLANES. Eavesdrop on exciting crosstalk 
between pilots, ground approach control, airport lower. 
Hear for yourself the disciplined voices hiding tenseness on 
lalk downs. Be with them when they have to take nerve 
rippling decisions In emergencies — Tune into the inter- 
national distress frequency. Covers the aircraft frequency 
band Including HEATHROW, GATWICK, LUTON. 
RING WAY. PBESTWICK ETC., ETC. CLEAR AS A BELL' 
This fantastic fully transistorised instrument can be 
bull! by anyone nine to ninety in under tuo hours. (Our 
design team built four — everyone worked first time). No 
knowledge of radio or electronics required. No soldering 
necessary. Fully Illustrated simply worded Instructions 
take you step-by-step. Uses standard PP3 battery. 81ze 
only 4|* x 3" x U". All you do Is extend rod aerial, place 
close to any ordinary medium-wave radio- (even tiny 
portables) HO CONNECTIONS WHATEVEB NEEDED. 
Use Indoors or outdoors. THERE WTLL BE ENORMOUS 
DEMAND FOB THIS NEW DESIGN, SEND NOW, ONLY 
12-87 (47/6) + 23p (4/6) p. & p. for all parts. Including case 
nuts, screws, wire, etc, etc. (Parts available separately). 



(45/-) 

Can be built in one evening 

At last! Alter trying countless circuits searching tor easy boild, work first-time short 

waver. Giving advanced world-wide performance, we chose this '8ky Boma". Anyone 

from 9 years up can follow the step-by-step. easy-aa-ABC, fully Illustrated Instruc- 
tions. (We built ten prototypes and everyone worked first time ) 
no soldering necessary. 76 stations logged on rod aerial in 30 
mins.— Russia, Africa, USA, Switzerland, etc. Experience thrills ^iijffi-a^jiiw— 
of world wide news, sport, music, etc. Eavesdrop on HISsS***^ _.- 

unusual broadcast*. Uses PP3 battery. Transistorised (no 

valves:). Size only 3" x 4|" x 1|*. As tremendous demand anticipated price held to only 12-26 (45/-) 
+ I7p Cl/r.) p. Jt p. for all parts incl. Cabinet, screws, instruction', etc. 1 Parti available separately). 





Only FIND BURIED TREASURE WITH THIS 

£4*95 READY BUILT & TESTED 



(99/-) 



has an 

exceptional 

Christmas 

present 



Treasure 

Locator 

Module 



BRAND NEW FULLY TBAHSISTOBISED PBINTED CIRCUIT METAL DETECTOB MODULE 

Heiulu hum and tested— iust plug in a PP3 battery and 'phones and it s working. Put It in a case. 
SeV. handT on anl YOU HAVE A PORTABLE TREASURE LOCATOR EASILY WORTH ABOOT 
«90' KTtremplv sensitive — penetrates through earth, sand, rock, wood, dirt, water, etc. — EASILY 
LOCATES COINS, GOLD. SILVER, WATCHES, JBWKLLEBY. igggM. METALLIC ORE. HI8- 
TOBICALBELICS. BURIED PIPES. KEYS. NAIL-IN-TRKKB. TO „ ETC !. Signals £**£*** 
\. v "****¥*" riitt'r, liicreRHine as vou near buried metallic objects. PRINTED CIRCUIT &KAKCM LUIIj 
W stable and sensitive It wUt detect certain objects buried SEVERAL FEET BELOW GROUND! GIVES 
CLEAR SIGNAL ON ONE COIN! You could even pay for your holidays wllh two or three days electronic 

h,„riirnn,htHa it's almost like having a licence to print money'. Unclaimed treasure now exceeds the 

eZldncd wealth ofaU nations. OBDEB NOW WHILE PBE8BHT STOCKS LAST TBKatBTOOUS 
DEMAND EXPECTED AT THIS REMARKABLY LOW PRICE. DEMONSTRATIONS DAILY. 
ORDERS DESPATCHED IN STRICT ROTATION. SEND NOW £4 95 I 30p carr. (99/- + 6/-) etc. 
(High quality Danish Stethoscope headphones £2-75 (85/-) extra if required). 



EXAMINE AT HOME FOR 7 DAYS. YOUR MONEY REFUNDED IN FULL IF NOT 100% DELIGHTED. 

•■!!>■■■ ■-■ ^ <•»•■-■>■,«•». •,■■«*«* ■ -rtn /wx m. miioo\ 8 Westbourne Grove, London W.2. 

CONCORD ELECTRONICS LTD (Dept. PW26) ?» *.,«..*.,- * <»<*«„,,, 

(STAFF WANTED FOR ALL DEPARTMENTS) 



Tubes. I minute ABC Cinema) 
(Callers Welcome 9 a.m. -6 p.m. Inc. Saturday 



661 




Garrard SP25 Mk III Gold 
GBOOH Teak plinth and tinted co 
Read/ wired for immediate use. 
Please add £1 -25 for post & packi 

■ es era u 

Please add 50p for P. ft P. 

Garrard SP2S Mk III ... £»• 
Garrard 202STC with 

stereo cart. ... ... £8' 

Garrard 202STC with ■ 

Sonotone 9TAHC ... £8 
Garrard 3000 with 

Sonotone 9TAHC ... £10 

Garrard SL65B £13- 

Garrard AP76 £19- 

Garrard 401 £17' 

B.S.R, MP60 £10- 

Pioneer PLI2AC £36 

ThorensTD 125 £62- 

Thorens 150 ABU ... £42- 

Goldring GL69'2 ... £19- 

Goldring GL69 P2 ... £26 

Goldring GL75 £27- 

Goldring GL75P £35- 



■ViliHUHiH 



Sinclair 2000 Mk. II 

Sinclair 3000 

Sinclair PRO 60/2 + Z30: 

PZ5 

Sinclair PRO 60/2 + Z30 

PZ6 

Sinclair PRO 60,2 + ZS0 

PZ8'Trans 

Sinclair AFU 

Teleton SAQ206B (New 

product) 

Wharfedale 



£15 00 
£17 75 



£22 95 
£4-70 



£19 95 
£49 75 



CARTRIDGES 



Please add lOp for P. ft P. 

Goldring G850 £3 75 

Goldring G800 £4 9s 

Goldring G800 

Goldring G800E 

Goldring G800SE 

Sonotone 9TAHC Diamond 

Shure M3DM 

Shure M44 5/7/C 

Shure M55E 

Shure M75E 

Shure V 15 Type 2 
Shure M44E 



Shure M3IE 
Shure M32E 
Audio-Techr 



Please add SOp for P. ft P. 

Alpha Highgate FA2 12 ... £27 50 

Alpha Highgate FA300 ... £29-00 

Alpha Highgate FA400 ... £33-00 

Armstrong 521 (cased) ... £41 95 

Amstrad 8000 £17 70 

Amstrad 8000 Mkll ... £18-95 

Amstrad IC2000 £3400 

Dulci 207 £15-95 

Dulci 207m £21 00 

Leak 30 Delta Range (New 

Prod.) £53-75 

Leak 70 Delta Range (New 

Prod.) £64-50 

Metrosound ST20 £24 75 

Metrosound ST20E ... £26-00 

Philips RS80 £18 00 

Pioneer SA500 £36-00 

Pioneer SA700 £65 00 

Pioneer SA900 £92 00 

Rogers Ravensbrook Chassis £35 00 

Rogers Ravensbrook Cased £39 00 
Rogers Ravensbourne Chassis £43 75 

Rogers Ravensbourne Cased £48 00 

Rotel 310 £3200 

Rotel 610 £49 00 

SansuiAUIOI £32 00 

Sansui AU666 £75 00 



£10 50 
£15 25 
£1 75 
£4-75 
£7 00 
£8-75 
£12 50 
£28 00 
£7 00 
£8 50 
£8 00 
£4-95 
£12 95 



mi:.i i :r--m-k^-H 




Please add 25 p for P. ft P. 
Smallest Radio in the world. 
5 years guarantee. 
Sinclair Micromatic 
Sinclair Micromatic (ready 

assembled) ... — "... ' 

Batteries I4p extra 



£2-75 
£3-25 




1.1. HH f° s 'Wwtfottd) 

MUiUU p| us 55 P post & packing 
Finished in real teak veneer with 
tinted dustcover. Ready to use (fully 
assembled). Suitable for Garrard 
SP25: 2025TC: 3000: AT60: 2000: 
2500: 3500: 5100: 1025: SL6SB. 
Also for B.S.R. McDONALD MP60 
and others Plinths and covers 
for AP76: AP75: SL72B: SL75: 
SL95B. £4-00 plus 55p post and 
packing. Also finished in walnut to 
match Japanese equipment — no extra 
charge. 




Oept. p.w.4.1 74 Pent onville Road, London, N1 . Telephone 01 -278 1 769 
Or: 4 High View Parade, Redbridge Lane East, Woodford Avenue, 
llford, Essex. Tel: 01-550 1086. 



Open Monday to Saturday 9. 30 a.m. to 

6 p.m. LATE NIGHT FRIDAY 7 p.m. 

MA II flRflCPC- ° rd «' >" lth confidence. Sena Postal Order. Cheque. 
I»I«IL UnUCno. Money Order. Bank Draft. Giro or Cash by Registered 
Mail. CALLERS: Please note that cheques can only be accepted togetner 
witn cheque cards (not Barclay Card). 



VALVES 



SAME DAY SERVICE 
NEW! TESTED 1 GUARANTEED! 



CETC 1R5, 185. 1T4. 334, 3V4, DAF91, DK9I. DK91, DL92. 01.94. 
» c I a Set of 4 (or £1-08. DAF96. DF9IS. DK9fi, DL9B. 4 for £1-48. 



JRS 

ISA 

1T4 

3S4 

8V4 

6040 

8V40 

5T3UT 

5Z4(i 

6/30L2 

8AL6 

BAMfi 

6AQ5 

6AT6 

6A06 

6BA6 

6BEn 

6BJ6 

6BW7 

6CD6C 1 

6F14 

6F23 

6P25 

6K7C 

6K8C 

6Q7G 

6SN7(iT 

6V60 

6V60T 

6X4 

6X50T 

7B7 

10P1S 

12AT7 

12AU8 

12AU7 

12AX7 

19B0fi(! 

sew 

20P3 
20P4 
25L60T 
2SU40T 



30C1 


as 


30C15 


ss 


30C17 


;u 


30C18 


n 


30F5 


iH 


30FLI 


ii 


30FLIJ 


;u 


30FL14 


HI 


30LI 


m 


SOUS 


w 


30L17 


71 


30P4 


H 


30P12 


78 


30P19 


,■>; 


30PL1 


HH 


30PL13 


;n 


30PL14 


Ml 


30PL15 


HO 


35L6GT 


4S 


38W4 


Mn 


35Z4CT 


a 


807 


« 


6063 


tin 


AC/VP2 


«■; 


B349 


hi, 


B7B9 


M 


CCU33 


n 


CY31 


u 


DAF91 


■lv. 


DAF96 


U 


DF33 


X8 


DF9I 


IK 


DF96 


lit) 


DH77 


80 


DK32 


M 


DK9.1 


us 


DK92 


HX 


DK96 


!« 


DL35 


411 


DL9-> 


m 


DL94 


m 


DL9fi 


m 


OY8B 


2b 



DV87 

DY802 

EABC80 

EAF42 

EB41 

F.B91 

EBC33 

EBC41 

EBC90 

F.BF80 

KBF89 

ECC81 

KOC82 

ECC83 

ECC85 

EOC804 

ECF80 

ECF82 

BCH30 

ECH42 

ECH81 

ECH83 

ECH84 

ECL80 

F.CL8J 

ECL86 

F.F39 

EF4I 

EF80 

EF83 

EF86 

EF89 

EF9I 

EF98 

EF183 

EF184 

EH90 

EL33 

EL34 

EL4I 

EL84 

F.L90 

EL95 



EL500 

EM80 

EMS I 

EM84 

EM87 

EYfll 

EY86 

EZ4II 

EZ41 

EZ80 

EZ8I 

(1Z30 

OZ32 

CZ34 

KT41 

KTfll 

KT6H 

LN319 

LN3-J9 

LN339 

NTS 

P8I 

PABCM0 

PC8« 

PC88 

PC98 

PC97 

PC900 

PCC84 

PUC83 

PCC88 

PCC89 

PCC189 

PCC80S 

PCK80 

POF82 

PCF86 

PCF800 

PCF801 

PCF802 

PCF805 

PCF806 

PCF808 



P-JL82 
PCL8R 
POL84 
PCL8S 
PCL86 
PCL88 
PCL800 
PBNA4 
PEN36C 
82IPFL200 



PL3fi 

PL81 

PL81A 

PL82 

PL8S 

PL84 

PL309 

PLS04 

PM84 

nua 

PY32 

PY33 

PY8I 

PY82 

PT83 

PY88 

PY800 

PY80I 

Rl'.i 

KM 

U2ft 

U2« 

1.47 

04H 

U50 

U02 

U78 

XH9I 

I! 193 

U251 

US0I 

Dsas 



•115 
•75 
•77 
•70 
•53 
•49 
-44 
•49 
•81 
•33 
•30 
•83 
•63 
•38 
£100 
■ 86 
• 88 
•28 
•86 
•28 
■33 
•34 
•34 
■30 
•56 
•64 
68 
■84 
•68 
•26 
•81 
•24 
•89 



UABC80 -32 

PAF42 -51 

UBC41 

UBF80 

UBF89 

UCC84 

UCC8S 

UCF80 

OCH42 

UCH81 

CCL82 

UCL83 

0F41 



D F89 

CL41 -67 

DM4 £1-00 

l"L84 
UM84 
UY41 
l'Y85 
VP4B 
Z77 



42 
•25 
•77 
•22 
Transiilors 

AC107 -17 

AC127 

A 1)140 

AF115 

AF116 

AF117 

AF118 

AFiee 

AF127 



0096 

0044 

OC48 

OC71 

OC72 

OC75 

OC81 

OC81D 

OC82 

OC82D 

Ol'170 



•18 
•87 
•20 
•20 
•20 
•48 
•17 
•17 
•26 
•18 
•12 
•12 
•18 
■12 
■12 
•18 
•12 
•18 



READERS RADIO 



85 TORQUAY GARDENS, REDBRIDGE, ILFORD, 
ESSEX. Tel. 01-550 7441. 

Postage on 1 valve 5p. on 2 or more valven 3p per valve extra. 
Any parcel insured against damage in transit 3p extra. 



When in LUTON, BEDS, you must visit the . . . 
SELF-SERVICE RADIO COMPONENTS SHOP 

Serve yourself from a selection of 1,200 boxes 
of Manufacturer's surplus stocks and save money. 

9 a.m. to 5.30 p.m. every day. 
Closed all day Wednesday. 



SURPLECTRONICS 

216 LEAGRAVE ROAD, LUTON, BEDS 



BUILD YOUR CIRCUITS 
on 

VEROBOARD 

— the Universal Wiring Board- 
obtainable from your local Retailer 
Trade enquiries to : 

NORMAN ROSE (ELECTRICAL) LTD. 
8 St. Chad's Place, Gray's Inn Road, London, W.C.1 
Technical enquiries to : 
VERO ELECTRONICS LTD. 
Industrial Estate, Chandler's Ford, Hants 




662 



0-8 Ammeter. 2in. square fall vision face lor flush 

mounting. Moving Iron Instrument. Ideal (or 

charger. Price 48$ each. 10 for 13-90. 

9 Vol Gramophone Unit. Collaro battery operated 

with pick up on unit plate. 4 speed auto-stop 

turnover cartridge. Price £2 50 plus 40p post and 

Insurance. 

Buy Time Sot Meter. Made by Sangamo Weston. 

3 types — one for each coin, 2Jp, Sp or lOp. Price 
£1 -76p each plus 25p post and insurance. 

Photo Electric Kit. Contains photo cell, relay. 
transistor and all parte to make light operated 
•witch. Originally £2 Limited quantity to clear. 
61 86p plus 20p post and ins. 

Dask/Hand Mike. Made by Acoa. Crystal Insert 
In neat plastic case which opens at right angles 
for desk or opens completely for hand holding. 
Good general purpose mike. Price 85a each. 
Printed Circuit Kit*. Hagato Pk. 3 facilities In kit 
form include printing, etching, resist removal, 
polishing and complete manufacture of printed 
sets to own specifications- Price 61 85 + 20p. 

4 Station Trsnsiitoriied Intercom. Solid state 
three transistor printed cct. master and 8 sub 
station push button/press talk system. 200mW 
output complete with installation accessories and 
9v. Everready power pack appro*, dimensions. 
Master 4£ xl,x 3* in. Bub station 3 X If X 4 In. 
Price 88 60+20p. 

Laboratory Instruments. For horizontal use In 
strong black reinforced bakelite cases with screw 
down terminals especially suitable for experi- 
ments and demonstrations. All have precision 
meters (manufacturers quoted accuracy of better 
than l'S%). Following available: 
D.C. Voltmeter 0-800. v f.i.4. moving coil mirror 
scale meter size approx. 5 X 41 X 11 In. Price 
81-76. 

D.C. Voltmeter 0-80r. J.x.4. moving coil mirror 
scale met r. Size approx. 5 X 4, X 1) In. Price 
81-76. 

AC/DO Mflliameters 8 range, moving Iron mirror 
scale meter. Range selection 26, 60 and 100mA 
by selection switch mirror scale (coil resistance 
marked) size. 7, x 5 X 3, in. type 35999/1. 
Price 89-76. 

Micrometer 100 micro amps, moving eon mirror 
scale precision meter (coil resistance marked) 
size, 6 x 4( x 2J in. type H/109/1 Price 88, 
Oalvometer 20-0-20 i.s.d. moving coll precision 
laboratory instrument of extremely high sensi- 
tivity (3 x 10-7 A per division), Size approx 
61 x 2 f x 2in. Price 86. - 

Aoos. 'G' Meters. For use with Aoos transducers 
and accelerometers or others of any make pro- 
vided they have a sensitivity of not less than 
17-6mV. per -g' and a linear output over the 
frequency range under Investigation. 
This is a precision instrument. It measures g' 
in three steps, 0-10, 0-100 and 0-1000 directly 
on a large clear meter scale 0-1. We have two 
models. Standard Model (ID001). Price Stf and: 
Auto cutout model (ID001) which has an Inbuilt 
circuit with relay to trip the external circuit 
(trip level is adjustable by a control which la 
virtually linear with the meter scale). The trip 
load may be up 2a. Once the circuit has been 
tripped it can be restored by a reset button. Price 
of this model is 818. Please note also we have 
Aoos Transducers ref. no. ID1001 In stock. 
Price 84 each. 

Farmeko Heptane Series C. Cora Transformers. 
These transformers are beautifully made, steel 
encased, stove enamelled black, upright mounting. 
All have normal 50cps. primary 230/240v. with 
primary screen and are new and unused. Small 
quantities only of each type available as follows : 
Model 8000/79. 276-0-27Sv. at 3S0mA, and 6-Sv. 
at 4-6a. Price 84-60: 60p post. 
Model 8000/71-890-216-0-216-290 at 126mA. 
and 2 at 6-8v. 8a. Price 84 60. 40p post. 
Model 49. 260v. at 10mA. 6-3v. at 8a., 6v. at 
076a. Price 88 + 30p. post. 

Modal 47. 620-0-620 at 9mA. 4 v. at 1A. Price 
84-60 + 40p post, 

Parmeko leptnne C, Con Chokes. These are 
encased and match the transformer above. 
Modal 6000/78 4H at 560mA. 88-60 + 40p post. 
Model 68. 10H at 1mA. 12 60 + 40p post. 
Model 49. 10H at 70mA. 81-60 + 30p post. 
Modal 69. 10H at 110mA. Price 82 + 40ppost. 
Pose Holders. Heavy duty type B.8.8. 88 440. 
Reyrolle power fuse holders. English Electric 
type 8.100.1. ex. equipment. Price 50p. 
Puses. H.E.C. 100A 160A. type BA . . . Eng. Elec- 
tric 100A. 160A. type 84TF . . . Kantark 80 A., 
new all at 25 p each. 

Electronic Car Ignition. In addition to the kite 
or 12 v. earn we can also supply systems for 6v. 
cars. These are not kits but made up and read, 
to work. Price 85-50. + SOp post. 
Carbon Resritori. We are now stocking these In a 
big way and wili"be pleased to quote special prices 
to quantity buyers. Made by Erie, Morganlte or 
Dubillar. 

Price per each 
1-9 10-99 xlOO-999 l.OOOup 

4 Watt lp 8t 89 SP 

lWatt 2p 18p 16p 186p 

2 Watt 4p 32p 30p 876p 

Special Eesiitor Assortment Oiler (1). 100 x } watt 
resistors made up of 2 each of 60 different values 
(airly evenly spaced between 1 ohma and 10 
meg*. Price SOp 

Special Resistor Assortment Offer (8) 1.000 X 1 
watt resistors made up of 20 each of 50 different 
values fairly evenly spaced between 1 ohms and 
90 megs. Price 84. 

••Mail Resistor Assortment Offer (8) As offer 1 
but 1 watt. Price 81. 

Special Resistor Assortment Offer (4). As offer 
2 but 1 watt. Price 88. 

18 Way Sub-Miniature MulH-oors Cable 7-0078 
copper cores each core P.V.C. Insulated and of 
different colour. P.V.C. covered overall and 
approx. 3/161n. thick. Price JSOp per yard. 





MICROSONIC KEYCHAIN RADIO 

7 transistor Keychain Radio in very pretty 
case, size 21 x 2t x 1 Jin.- — complete with 
leather zipped bag. 7 transistor, ferrlte rod. 
Loudspeaker. 

In transit from the East these sets suffered 
corrosion as the batteries were left In them 
but when this corrosion is cleared away they 
should work — offered without guarantee 
except that they are new. Price only 61 £6 
less batteries plus 38p. post 6 for 87 post free. 
Pair of rechargeable batteries and charger SSp. 

24-HOUR TIME SWITCH 

Made by Smiths, these are AC mains operated, 
NOT CLOCKWORK. Ideal for mounting on rack 
or shelf or can be built into box with ISA socket. 
2 completely adjustable time periods per 24 
hours, 5 amp changeover contacts win switch 
circuit on or off during these periods. 82-60 post 
and ins. 23p. Additional time contacts 60p pair 

THE FULL-FI STEREO SIX 

The amplifier 

sensation of the year 
Von will be amazed at the 
fullness of reproduction and at 
the added qualities your records 
or tuner will reproduce. Built 
into metal cabinet elegantly 
styled in simulated teak finished 
to blend with modern furnishings, this amplifier uses 
an Integrated solid state circuit with an output power of 6 watts R.M.8. split 
over the two channels. The amplifier is Ideal for use with normal pick-ups and 
tuners, it has a double wound mains transformer and ganged volume and tone 
controls-- also switching for Mono to Stereo, tuner or pick-up. Other controls 
include "treble lift and cut", "balance" and separate mains on/off switch. 
UNREPEATABLE PRICE is 89 plus S8p poet and insurance. 




THIS MONTH'S SNIP 




POCKET CIRCUIT TESTER 

Test continuity for any low resistance circuit, house wiring, 
car electrics. Tests polarity of diodes and rectifiers. Also 
ideal size for conversion to signal Injector (circuit supplied) 
SOp or 2 for SOp Post paid. 




TANGENTIAL HEATER UNITS 

This beater unit is the very latest type, most 
efficient, and quiet running. Is as fitted in Hoover 
and blower heaters costing 815 and more. We have 
a few only. Comprises motor, impeller. 2kW. 
element and lkW. element allowing switching 1, 
2 and SkW. and with thermal safety cut-out. Can 
be fitted into any metal line case or cabinet. Only 
need control switch. MM- 2kW. Model as above 
except 2 kilowatts MM. Don't miss this. 
Control Switch SSp. P. * P. 40p. 

CENTRIFUGAL FAN 

Mains operated, turbo-blower type. Pressed steel 
Housing contains motor and aluminium impeller. 
Motor Is l/10th hp giving considerable air flow 
bat virtually no noise. Approx. dimensions 101" 
wide by 12' dla. Outlet into trunking 10,' X 41'. 
M'M + 81. 



DISTRIBUTION PANELS 



Just what you need for work bench or lab. 

4 x IS amp sockets, in metal box to take 

standard 13 amp fused plugs and on/off switch with neon warning light Suppled 

complete with 7 feet of heavy cable. Wired up ready to work, 82 less plug 

£8 85 with fitted IS amp plug: 88 40 with fitted 16 amp plug, plus 28p P. * I. 



CAPACITOR 



DISCHARGE CAR IGNITION 

This system which has proved to be amazingly 
efficient and reliable was first described in the Wire- 
less World about a year ago. We can supply kit of 
parts tor Improved and even more efficient version, 
price 84 86. Wnen ordering please state whether 
for positive or negative systems. Plus 30p post. 



15 WATT »2in. HI-FI SPEAKER 

16 WATT If'" HI-PI SPEAKER. Is undoubtedly one 
of the finest loudspeakers that we have ever offered, 
produced by one of the country's most famous makers. 
It has a die-cast metal frame and Is strongly recom- 
mended for Hi-Fi and public address. Handling 16W 
R.MS.— Cone moulded fibre — Freq. response SO 
10,000 c.p.8.— specify 3 or 15 ohms. Chassis dlam. 
Win — 12|ln over mounting lugs. Overall height 5Jln. 
A 810 speaker offered this month for M-75 plus SOp. 
post and ins. 




2 OCTAVE MINI ORGAN 

As featured In this issue. Send 8.A.E. for list of parts. 



Zl 



Snap Action Slide Switch. Rated 5a. 240v. Made 
by Arrow. Type fitted In the handles of electric 
drills, vacuums, etc. Sp each, 10 for 46p. 
■umJoator Tubs*. For digital Instruments, counters 
timers, clocks, eto. Hi-vac XN, 3. Price 61 46 each. 
10 for all. 

1 8 8 8888 8 Switch-Containing a 16 amp. change over 
switch operated by a diaphram which in turn is 
operated by air pressure through a small metal 
tube. The operating pressure is adjustable but Is 
set to operate in approx. 10 In. of water. These are 
quite low pressure devices and can in fact be 
operated simply by blowing into the Inlet tube. 
Original use was for washing machines to turn off 
water when tub has reached correct level but no 
doubt has many other applications. SOp each. 
10 for 84 60. 

Papal Miniature Extractor Fans. Beautifully made 
as are all papst motors- Intended for cooling 
computers but suitable for any equipment. Size 
4,ln. square and llln. thick. Price M each. Post 
and Insurance 20p. 

Commutator Motor. Small. Size approx. Sin. plan 
Jin. of shaft, Sin. high X l|ln. wide, but high 
speed and very powerful. These motors operate 
from the mains. Are particularly useful as they 
can be speed controlled by our thyrlstor kit or by 
variable resistor. 81 each. 

Anto Light Kit. The circuit for this appeared in 
Practical Wlreltu. October issue. It is a simple 
circuit but has many uses: Parking light, porch 
light, eto. Uses light cell and two transistors. 
Complete kit, no case 96p. Suitable case SOp. 
Charger Kit. Comprises of 3 amp. transformer. 
6 amp. rectifier and a pair of hefty crocodile clips. 
With wiring diagram. 81-40 plus 20p post and 
Insurance. 

M hr. Clock Switch. In metal case with 13 amp. 
socket Smiths movement, 2 ons and 2 ofls per 24 
hours. Very neatly made and finished. Original 
retail price 87 each. Few only, new and perfect. 
84.89 each. 

P.E. Gemini Amplifier. This amplifier is a 30 X 
SO watt stereo amplifier and pre-amplmer of ex- 
ceptionally high performance. The performance 
Is certainly equal to anything one can buy no 
matter what the cost. The P.E. Gemini has been 
designed for both hi-fi applications and for use with 
discotheques and fort his reason, has a microphone 
Input that can be mixed with any other Input. The 
amplifier Is designed and Is thus capable of driving 
two Quad electrostatic speakers and is thus capable 
of driving any other speakers, provided they are 
of the correct impedance. We offer the complete 
kit cabinets at 846. Price list Including reprint of 
data. 66* post paid. ' 

■son Indicator Lamps. With amber lens, standard 
type with built In resistor for mains. lOp each. 
10 for 90b. _ _ 

Condensers. Another addition to our range. 500uF 
at 60v. 169 each. 10 for 81.25. 
Thermistor Bead Type. For instrument*., medical 
applications, etc. ITT No. GL23, 7Sp each. 10 for 
86-76. 

S Cor* Mains Leads. Special offer this month Is a 
6ft. lead with 23/36 cores and coloured according 
to the new code I.e. Brown— live; Yellow/Green— 
earth; Blue — neutral. Price 69 each or 10 for 50p. 



P.W. Constructor Projects 
As described In this and past Issues. We can 
probably supply components. Send 8.A.E. 
for list, naming project. 





TREASURE TRACER 

Complete Kit (except wooden 
battens) to make the metal 
detector as the circuit in Practical 
Wireless August issue. £2 95 plus 
20p post and Insurance. 



AINS RELAY BARGAIN 

Special this month are some single, 
double and treble pole changeover 
relays. Contacts rated at 15 amps. 
Operating coll wound for 240V A.C 
Good British Make. Ex-unused equip- 
ment. Slxe approx. 1J* X I*. 
Open construction 

Bingle pole 25p each 10 for 82 26 
Treble pole 40p each, 10 for 880 6 

Flex Connector 
A quick way to connect 
equipment to the mains 
safely and firmly — L., N. 
and K. coded to new 
colour scheme; discon- 
nection by plage prevents 
accidental switching on: 
has sockets which allow 
insertion of meter without disconnexion cable 
inlets firmly hold one hair wire on up to four 
7.029 cables. Mp each 

THYRISTOR 
LIGHT DIMMER 

For any lamp up to 200 watt. 
Mounted on switch plate to fit in 
place of standard switch. Virtually 
no radio interferences. Price £1 
plus 20p post and Insurance. 




«9 



Where postage is not stated then orders 
over 86 are post tree. Below 86 add SOp. 
Semi-conductors add 6p post. Over £1 post 
free. S.A.E. with enquiries please. 



J. BULL (ELECTRICAL) LTD. 

Dept. P.W. 7, Park Street, Croydon CRO I YD 



663 



JUSTBEGINNING? 

f jkjji 8-Watt, 10-Transistor 
(/TAT Stereo Amplifier R.137 




Separate tone i 
volume controls for 
each channel, inputs for turntable 
(ceramic cartridge),tuner and 
tape.Attractive black crackle finish with 
brushed aluminium front.Frequency 
response :70-20,000 Hz ±3dB.Output: 4 watts 
per channel (« 8ohms.lnputs:Phono80mV; 
tuner/aux80mV. 



Normal retail 
price : £14-70 



r 



^ 



5-Watt Transistor Stereo Amplifier Chassis R.123 

Completely self-contained.fully transistorised, mains-powered 
(240vAC) amplifier, needing only cabinet and knobs. Ideal for 
adapting mono players to stereo. Frequency response:40- 
17,000 Hz ±3dB.Output:2-5 watts per channel @ 8 ohms. Input: 
Phono 600m V. /fiw^>v 

Normal 

retail price : £.7-30 





AM/FM/MPX 
Stereo Tuner, 
Amplifier 
R.124 

A top quality 
amplifier 

wifh facility for re- 
ceiving stereo broadcasts. 
Separate bass and treble con- 
trols, automatic frequency re- 
sponse, stereo headphone socket.output power:8 watts. FM 
frequency range 88-108 M Hz;AM frequency range 535-1605 K Hz. 
Inputs for turntable (ceramic cartridge) and tape. Frequency 
response :50-1 0,000 Hz ~3dB.Output:4 watts per channel g 8 
ohms. Inputs :Phono 200m V.tape 100m V.FM:Sensitivity 20uV, 
stereo separation 26dB,image rejection 55dB.AM:Sensitivity 
300uV. 

Normal retail X^^PCk Q*^ 



price i £4200 ROC price: 



WcnJdMdereceptioii 

Professional Solid-state, Four-band 
Communications Receiver R.135 

Fully transistorised with continuous coverage from 555K Hz to 
30 M Hz in four bands (with illuminated bandspread for 160-10 
metres). Incorporates internal speaker, automatic noise limiter, 
SSB/AM/CW switch.AVC switch.S Meter.Receive and Standby 
switch, external socket for headphone or speaker.bandspread 
control, BFO control, on/off/AF gain, band selector, antenna 
trimmer and RF gain. Runs off 240 v AC, batteries or any 12 v DC 
negative ground source. Frequency ranges (in mHz):Band A, 
535-1-6;B,1-55-4-5;C,4-5-13;D,13-30.Sensitivity:0-5uV@30mHz. 
Bandspread :10-160 metres. 



Normal 
retail price : 
£6500 



ROC 
price: 



£45.00 




®£? 9 © © © © 




Stereo 
Cassette 
Tape 
Unit R.142 



Complete stereo record and playback 
unit with line and microphone inputs. 
Fitted with tape counter.separate pause 
control.recording level metres for each 
channel, pop-up cassette ejection. Sup- 
plied complete with two pencil micro- 
phones. Wow & flutter better than 0-3%, 
frequency response 100-10,000 Hz.Tape 
speed:1JIPS,4-75CMS.Rewind time: 
Better than 60 sec (C.60 cassette). 
Normal retail price : £65-00 



ROC 

price 

£49.50 



We don't want you to 

Every piece of electronic or audio-equipment we 
sell is builtto our specifications.lt comes 
complete with a Guarantee.And it's tested before 
it leaves us. 

We bend over backwards in our advertising to 
make sure everything we say is factually accurate. 
But.buying mail-order.even though you're buying 
from us, we accept you could still end up with a 
piece of equipment that's not exactly what you 
wanted. And we think that's unfair. 



664 



&«* 




Normal retail price : £9-40 



Headphone Radio 
R.143 

For completely private 
listening without the 
/distortion of the ordinary 
earphone adaptor. Battery 
operated; PP3. Fully 
transistorised. Frequency 
range :535-1 600 KHz. 
Medium Wave Band. 
Maximum output :300mW. 



ROC 
price 

£6.90 



r *▼' 



■for the pKce 




of oner 



Matched Stereo 
Speakers R.446 




£16.40 



Heavily lagged teak finish cabinets each with 
large dual cone base unit and separate 

tweeter.Power handling :10 watts peak; 

frequency range:40-18,000 Hz, impedance: 
8ohms.Size:14x8l x6i. ., . _„ 

Normal retail price : £19-60 



BPn 




with a frequency res- 
ponse of 30-15,000 Hz 
for real listening 
pleasure. Complete 
with jack plug. Im- 
pedance 8-16 ohms. 
Normal retail price : £2 95 



Dorit read this! 

10-watt Transistor Stereo Amplifier R.136 

Ganged volume, balance and tone controls. Inputs for turn- 
table(ceramic cartridge), tuner(see R.l34)or tape. Oiled walnut 
case with satin finish aluminium front panel. Frequency 
response 50-10,000 Hz ; 3dB. Output: 
5 watts per channel « 8 ohms. 
lnputs:Phono 100mV. ^*trfTflff///, 
tuner/aux 100mV. _^*rif!lflffl/ffi//////l 




Normal 
retail price 
£20-46 



ROC price: 

£14.00 



pay for your mistakes 

So we've got a proposition for you. 
If you buy a piece of Roc equipment, and it's not 
quite what you expected, send it back within seven 
days, and as long as it's as good as new we'll give 
you your money back. O.K? 

Return of post mail-order service;orders over £10 post free, (U.K. 
only) add 25p for p 4 p to orders under £10. HP terms available. 

ROC ELECTRONICS LIMITED 

B Jory Esu 193A Edgwnii- Rcl.. London W2 1ET. 01-723 621' 

Callci s .il Shop .welcome 9-6 Mon lo Sal ( Thurs 1pm) 




AM/FM/MPX 

Stereo Tuner 
R.134 



Matching unit tp~the 

R.136 amplifier.Covers 

AM and FM tuning bands 

with automatic stereo signal 

light. FM frequency range:88-108mHz; 

AM frequency range :535-1605kHz. 

FM:Sensitivity 5uV, stereo separation 

25dB ii 1kHz, image rejection 50dB. 

AM:Sensitivity250uV. 

Normal retail price : £28-60 



THE RADIO 
CONSTRUCTOR 

NOVEMBER ISSUE 

features 

AUDIO FREQUENCY METER 

by J. T. Neill 

Part one of a two part article describing a compact 
frequency meter, with analogue display, working at 
audio frequencies and employing an integrated circuit 
for ease of construction. 

Also featured 

THE "DROITWICH" CAR RADIO 

by Sir Douglas Hall, K.C.M.G. 

PLUS 

■ MORE CONSTRUCTIONAL PROJECTS 

■ NEWS COVERAGE 

■ SHORT WAVE SCENE 

■ SUPPORTING FEATURES 

■ DATA SHEET 56 

ON SALE NOW 20p 




Copies may also be obtained direct from the Publishers 

24p including postage. Published by: 

Data Publications Ltd., 57 Maida Vale, London W.9 



I FAMJASJIC BA*GM H Of UK! 

Transistorised Stereophonic High Fidelity 
AM FM Tuner Amplifier System. 



FABULOUS VALUE 




Thissynem includei thi> elecantly -i.lcd solid tUU Teak t.n.ilicd cabinet 
tuner/amplifier. Covering VHF/FM. Short, medium and Ion* waveband!. The 
atesl : 4 Speed B.S.R. Mono/Stereo record changer with 2-IOin. x 6ir 
matching ell'Ptical speakers. A complete Hi-Fi Stereo Radiogram 
at las* than half normal price. ____ , .. 
Easily /IttW no technical SPECIAL OFFER 

know led f necessary. 

Credit Terms avail- 
able. First monthly 
payment of £5-83 fol- 
lowed by 9 monthly 
payments of £4 95 
Total Credit Sale Price 
£49-50. Send £5-83 tod.,, 



low. System Ten-Ten; 4 speed BSR aucochange> 
*"?l.plu* «olid state amplifier. 20 watt total output 



Hi-Fi stereo at a 

with cue and paus 

Frequency response 20-20,000 Hi. 

enclosures — 100% complete, 

ONLY 

1 4>Q1 C 552E SALE TERMS: Send £4-93 (being the first of TEN 
«■-» #■! monthly payments of £405 plus 88p Carriage and Pack- 

DOWN £ g)- 1 %^ ■ ol !°T re = by N A N Ai? ,ontfil >' P'rments of £4 05 
lijjyvn (Total Credit Sale Price £40 50) 

EASY TO INSTALL M0 TECHNICAL KN0WLE0GE REQUIRE0. 



Post i 
NOW for. 

mfletsi 



m^Wo CAL, - un ^ tLcoMt 



ME FREE DETAILS OF YOUR. RANGE Z 

Name ■ 

Address ",'.'. P 12 1 ■ 

10O.Ch«e Side London MM ■ 
T.I: 01-886 3733/9666 



SPEAKER SELECTION 

(THE SPEAKER 68(W) SHAFTESBURY 
SPECIALISTS) fflf, LOHDOH, Wl 

(MAIL ORDER ONLY) TEL. 01 437 3066 



AKAI 

ASE9S 

ASE20 

AK6 

K60 

K180 .. 

BEYER 

DT8O0/K100 .. 

DT109/K109 .. 

DT480 

DT485 

CLARK 

300 .. 

100 

EAGLE 

SE60 .. 

SE80 .. 

SE100 

HOSIDEN 

DH 02S 

HOWLAND WEST 

NIKKO 3S .. 

NIKKO 4SV 

NIKKO 4ST 

NIKKO 8S .. 

NIKKO 77S .. 

KOSS 

K711 (DEVILS) 

K6 

K6LC 

K0727 

PRO 4AA .. 

ESP 6 

ESP 9 



HEADPHONES 



£5 SO A 
£7 50 A 

£1150 A 
£23 00 B 

£11 00 A 
£19 00 A 
£22 00 B 
£27 00 B 

£7 50 A 
£18 00 B 

£7 SO A 
£13 50 A 
£14 50 A 

£2-25 A 

£4 00 A 
£••50 A 

£7 00 A 
£11 00 A 
£12 50 A 

£8 00 A 
£9 50 A 
£11 00 A 
£12 50 A 
£22 00 B 
£35 50 B 
£54 00 B 



MIDLAND 

SA700 

PWB 

NSE (Electrostatic) 

PIONEER 

SE 2P 

SE 30 

RODGERS 

RAVENSBROOK 
ROTEL 

RH600.. 
RH711.. 

SANSUI 

SS2 .. 
SS20 .. 

SENNHEISSER 

HD414 

STAX 

SR3/SRD5 .. 
TELETON 
SH301 
SH 307 

TOSHIBA 

HR80 .. 

WHARFEDALE 

DD1 .. 



£3 00 A 
£31 00 B 



£5 50 A 
£10 50 A 



£5 00 A 
£8 00 A 



£•25 A 
£14 50 A 



£8 00 A 
£38 00 B 



£3 25 A 
£4 25 A 



£4 75 A 
£9 50 A 



DELIVERY CHARGES 
A .. 30p 

B SOp 

(Including insurance) 



S2S2!ff °, f Speaker prices below, delivered free. Many more makes 
available please telephone or write for quotation. 

WHARFEDALE KITS 

MELTON II .. £49 50 UNIT 3 . . £20 50 

DOVEDALE III £61-00 UNIT 4 £26 50 

S LINTON II.. .. £4000 UNITS " V. £37 IS 



666 









LIMITED 



FULLY TESTED AND MARKED 





to 


AC 107 


0-15 


AC 126 


0-13 


AC 127 


0-17 


AC 128 


0-13 


AC 176 


015 


ACYI7 


0-15 




0-37 


AFI86 


0-50 


AFI39 


0-37 




0-15 


BCI7I 


BCI07 0-13 


BCI72 


BCI08 0-11 




0-15 


BF274 


0-15 


BFYSO 


0-20 


BSY2S 


0-57 


BSY26 


0-13 


BSY27 


0-13 


BSY28 


0-13 


BSY29 


0-13 


BSY95A 


0-13 


OC4I 


0-13 


OC44 


0-13 


OC4S 


0-13 


OC7I 


0-13 


OC72 


0-13 


OC73 


0-17 




0-13 


OC8ID 


0-11 


OC83 


0-20 


OCI39 


0-13 


OCI40 


0-17 





fa 


OCI70 


0-23 


OCI7I 


0-23 


OC200 


0-25 


OC20I 


0-25 


2G30I 


0-13 


2G303 


0-13 


2N7II 


0-50 


2N 1302-3 


0-20 


2NI30-4-S 


0-25 


2N 1 306-7 


0-30 


2N 1 308-9 


0-35 


2N38I9FET 


0-45 


Powir 






[ 


OC20 


0-50 


OC23 


0-30 


OC25 


0-25 


OC26 


0-25 


OC28 


0-30 


OC35 


0-25 


OC36 


0-37 




0-30 




1-25 




015 


2N3055 


0-63 


Diode. 




AAY42 




OA95 


0-19 




0-09 


OA8I 


0-0* 


IN9IM 


0-07 



FREE! 

PACKS OF YOUR OWN CHOICE UP TO 
THE VALUE OF 50p WITH ORDERS 
OVER £4 



CLEARANCE LINES 



COLOUR T.V. LINE OUTPUT 
TRANSFORMERS 

Oesigned to five 25k V when used with PL509 
and PY500 valves. As removed from colour 
receivers at the factory. 

NOW ONLY 50p each 
post and pock ins 23p. 

1 Amo Plastic Rectifiers. These are voltage, reverse 
Polar ty and other rejects Irom the BY 127 range. Ideal 
for low voltage Power Units etc. Price £1 per 100. 



Quantity 

BBI0S Varicap Diodes 
OC7I or 72 Fully Tested 

Unmarked 
Matched Sets I-OC44 and 

2-OC45's. Per Set. 
Matched Sets of OC45's 1st 

and 2nd IF 
OA47 Gold-Bonded Diodes. 

Marked and Tested 
I -watt Zener Diodes 7-5, 24. 

27. 30. 36. 43 Volts 
10-watt Zener Diodes S-l. 

8 2 II. 13, 16, 24. 30. 100 

Volts 
Micro Switches. S/P. C/O 
I -amp Bridge Rec's, 25-volt 



1-10 10-50 50 + 
I Op 8p 6p 



5p Sp 

25p 20p 



ISp 
3p 
5p 



lip 
3p 



4p 
I5p 
tOp 
2p 
Jp 



20p I7p ISp 
15 p 10 p ISp 
25p lip 20p 



INTEGRATED CIRCUITS 

SL403D Audio Amp.. 3-Watts 200 1-95 



1-80 
35p 



709C Linear Opp. Amp. 50p 40p 
Gates, Factory Marked and 

Tested by A.E.I. 2Sp 22p 20p 
I. K. Flip-Flops Factory. 

Marked and Tested by A.E.I. 40p 35p JOp 

PA234 I -watt Audio Amp. 1-00 »0p 80p 

UL9I4 Dual 2 1,'P Gate 40p 35p 30p 

~ BUMPER BUNDLES 

These parcels contain all types of surplus elec- 
tronic components, printed panels, switches, 
potentiometers, transistors and diodes, etc. 
2 LBS IN WEIGHT FOR / I 

o.. » -„,4 .,...1,;..*. ic~ *- ■ 



Post and packing 25p. 



OUR VERY POPULAR 3p TRANSISTORS 

FULLY TESTED & GUARANTEED 
TYPE " A " PNP Silicon alloy, metal TO-5 can. 2S300 type, direct replacement for the OC200/203 range. 
TYPE " B" PNP Silicon, plastic encapsulation, low voltage but good gain, these are of the 2N3702/3 

and 2N40S9/62 range. 
TYPE " E " PNP Germanium AF or RF — please state on order. Fully marked and tested. 
TYPE " F • "NPN Silicon plastic encapsulation, low noise amplifier of the 2N3708, 9. 10, 1 1. 



BULK BUYING CORNER 

NPN/ PNP Silicon Planar Transistors TO- 1 8 
mixed untested similar to 2N706-6A-8, 
BSY26-7A9-95A and BCY70 etc. £4-25 per 
500. U per 1000. 

NPN Silicon Planar transistors plastic encap- 
sulation untested similar to 2N3707 to 3711. 
£4-25 per 500. £8 per 1000. 

Silicon planat diodes do-7 glass similar to 
OAZOO -202, BAY3I-36. £4-50 per 1000. 

NPN 'PNP Silicon planar transistors plastic 
TO-18 similar to BCII3-4. BCI53-4. BFI53- 
160. etc. £4-25 per 500. £8 per 1000. 

NPN Silicon planar transistors TO-5 can 
similar to BCI42/3. BFY50-2-3. £5-25 per 500, 
£10 per 1000. 

OC44, OC45 transistors fully marked and 
tested 500 to 999, 8p each, 1000+ 6p each. 

OC7I transistors fully marked and tested, 
500 to 999. 6 each. 1000+ 5p each. 

A amp minature plastic diodes IN400I at 
500 to 999. 4p each. 1000+ 3p each. 
IN4O04 at 500 to 999, 5p each, 1000+ 4p each. 
IN4006 at 500 to 999, 6p each. 1000+ 5p each. 
IN4O07 at 500 to 999, Speach, 1000+ 7p each. 



NE W UNMARKED UNTES TED PARS 

B66 I CQ Germanium Diodes 



lin. glass type 



50p 



200 



Trans, manufacturers' rejects 
all types NPN, PNP. Sil. and 
Germ. 



50p 



100 



Silicon Diodes DO-7 glass 
equiv. to OA200. OA202 



50p 



50 



Sil. Diodes sub. min. 
IN9I4 and IN9I6 types 



SOp 



50 



Sil. Trans. NPN. PNP 
equiv. to OC200/I, 
2N706A. BSY95A. etc. 



50p 



10 



7 Watt Zener Diode 
Mixed Voltages 



40 



250mW. Zener Diodes 
DO-7 Min. Glass Type 



50p 

lop 



25 



Mixed volts, l± watt Zener 
Top hat type 



50p 



30 



MAT Series " alloy " pnp 
Transistors 



50p 



30 



Top Hat Silicon Rectifiers, 
750mA. Mixed volts 



50p 



Experimenters' Pak of 
Integrated Circuits. Data 
supplied 



50p 



20 



BY 126/7 Type Silicon 
Rectifiers, I amp plastic. 
Mixed volts. 



50p 



NEW TESTED AND GUARANTEED PAKS 



0-3 to 0-5V. 0-5 to 2mA. 



50p 



IN4007 Sil. Rec. diodes. 
1.000 PIV lamp plastic 



50p 



10 



Reed Switches, mixed types 
large and small 



50p 



200 



Mixed Capacitors. Postage 1 3p 
Approx. quantity, counted by 
weight 



50p 



250 



Mixed Resistors. Postage I Op. 
Approx. quantity counted by 
weight 



50p 



40 



Wirewound Resistors. Mixed 
types and values. Postage 8p. 



BY 1 27 Sil. Recs. 
1000 PIV. I amp. pla 



OCP7I Light Sensitive 
Photo Transistor 



SOp 
SOp 
lOp 



50 



NKTI55P59 Germ, diodes, 
brand new stock clearance 



10 



OC7I/7S uncoded black glass 
type PNP Germ. 



10 



OC8I/8ID uncoded white 
glass type PNP Germ. 



50p 
lOp 
H)p 



20 



OC200;if2/3 PNP Sili 
uncoded TO-5 can 



50p 



20 



OA47 gold bonded diodes 
coded MCS2 



50p 



F.E.T. PRICE BREAKTHROUGH!! 

This field effect transistor is the 
2N3823 in a plastic encapsulation, 
coded as 3823E. It is also an excellent 
replacement for the 2N38I9. 
Data sheet supplied with device. 
I -10 30p each. 10-50 25p each, 50+ 
20p each. 



Make a Rev. Counter for your Car. The 

'TACHO BLOCK'. This encapsulated 
block will turn any 0-1 mA meter into_ 
linear and accurate rev. 
counter for any car. 



ImA meter into a 

£1 each 



FREE CATALOGUE AND LISTS 
for:— 

TRANSISTORS, RECTIFIERS, 

DIODES, 

INTEGRATED CIRCUITS 

FULL PRE-PAK LISTS 

& SUBSTITUTION CHART 



MINIMUM ORDER 50p CASH WITH 
ORDER PLEASE. Add lOp post and 
packing per order. OVERSEAS ADD 
EXTRA FOR AIRMAIL. 



8 RELAYS FOR £l 

Various Contacts and Coil 
Resistances. No individual 
selection. Post & Packing 25p 



WRITTEN GUARANTEE WITH ALL OUR SEMICONDUCTORS 



._ ■■ i^- ■ VPI DEPT. D, 222-224 WEST ROAD, WESTCLIFF-ON-SEA, ESSEX 

Hl'f | |L-"I B #%l%. La* I U TELEPHONE: SOUTHEND (0702) 46344 



5 



667 



..... 




High Salary 

A Dream House 

A New Car 

And A Secure Future 

Get into the Computer 

Industry the fast and 

easy way. 

Now for the first time, anybody (no special qualifications 
are needed) can train outside the computer industry for 
an exciting career as a computer operator in only 4 
weeks — and can earn £2,000 + + p.a. 

How? We are the only commercial training organisation 

in the U.K. permitted to use the famous 

'Eduputer'. 

JOBS GALORE! 144,000 new 

operators will be needed over the 

next five years alone. And the 

moment you qualify our 

exclusive computer appointments 

bureau introduces you to 

computer users everywhere. 

This is your big opportunity to get 

out of a rut and into the world's 

fastest growing industry. 

Telephone: (01) 734 2874 

Or post the coupon 

today for full details 

FREE and without 

obligation. 



London Computer Operators 
Training Centre 

CSt, Oxford House. 9/15, Oxford Street, London, W1. 
Telephone: 01-734 2874 

127/131 The Piazza, Dept. C21. Piccadilly Plaza, 
Manchester 1 . Telephone : 061 -236 2935. 

Please send me your FREE illustrated brochure on exclusive 
Eduputer 'hands on' training for computer operating. 

Name „ 

Add ress 



668 



Send for Heathkit - and send for the best 




Heathkit comes direct from the world's leading 
suppliers of top-quality electronic equipment. 
You assemble your components using the 
unique Heathkit 'step-and-check' method and 
there's a team of experts ready to help and advise 
you on any problem. But you won't need them. 
Hardly anyone does! Send for your FREE 
catalogue — NOW. 

AD27 stereo 'Compact' with magnetic cartridge 
fm section -x- tuning range 88-108 Mhz •* sensitivity 
5 microvolts * frequency response 20-15,000 Hz 
■* stereo separation 1,000 Hz * stereo decoder included 



amplifier section ■* continuous power output rms 
10 watts per channel •* music power output 1 5 watts 
per channel (both to I.H.F. standard) #■ total harmonic 
distortion at full output less than 1% * speaker output 
impedance 4 ohms ■* frequency response 12-60 kHz 
( -f or - 1 Db) #• tape recorder output with 500 mv 
sensitivity at an impedance of 3,500 ohms 

("pfease send me details of your complete range of kits. | 






address 



1 Schbr ii &m y mr CcW*» 



HEATH (GLOUCESTER) LLMITED, GLOUCESTER, GL2 6EE 



669 



_J 



THE SOUND 



A COMPLETELY NEW DESIGN 
FURTHER IMPROVED IN BOTH 
APPEARANCE and PERFORM- 
ANCE. 



HI-FI CENTRES 
LTD. 



OF QUALITY 



REPRESENTING 

VALUE FAR HIGHER THAN 

THE PRICES SUGGEST. 



SUPER 30 MkllLHI-FI STEREO AMPLIFIER 



Only high grade components by 
leading manufacturers. 
COMPLETE KIT OF PARTS 



Carr. e5p 

£33-75 



Or FACTORY BUILT 

with 12 months guarantee 
Dep. £5-75 and 9 monthly payments 
£)-M (Total £37 ■») 

Or FACTORY BUILT In cabinet as Illustrated /n -, r 

Oep. £« and 9 monthly payments £3-M (Total £40-74) t JO ' / 3 
PRINTED CIRCUITRY. TWENTY SILICON TRANSISTORS. 
FOUR DIODES, FOUR RECTIFIERS. 

TECHNICAL DETAILS (Applying to each channel where appropriate) 
CONTROLS: PUSH-BUTTON SELECTOR (1) Disc (2) Radio (3) Tape (4) 
(9) Mono R (6) SPEAKER DIS. (7) Mains on/off. 
Bass, Treble, and Balance. Plus Ceramic/Mag P.U. Switch 
OUTPUT: 15 watts R.M.S. (Continuous) Into 8 ohms. 
10 watts R.M.S. (Continuous) Into 15 ohms. 



* t? 



Q 



-* SATIN SILVER METAL FACIA with black letter- 
ing. Black edged knobs with bright silver centres. 

• PUSH-BUTTON SELECTOR SWITCHING 

• NEON INDICATOR 

• JACK SOCKET FOR HEADPHONES 

• CABINETED MODEL VENEERED IN SATIN 
TEAK. SUITABLE FOR ANY MODERN PICK- 
UP CARTRIDGE CERAMIC or MAGNETIC, 
REGARDLESS OF PRICE. 

WE RECOMMEND USE WITH THE BEST 
ANCILLARY EQUIPMENT THAT CAN BE 
AFFORDED. 

HUM 4 NOISE -75dBMIn. Vol. -65dB Full Vol. HARMONIC DISTORTION 
FREQUENCY RESPONSE: -3dB 7Hi to 70KHr 0-1% at 1000 Hi 10 Watts 
TREBLE CONTROL: +16dB to -12dB at 14KHz 
MonoL BASS CONTROL: +17dB to -18dB at 40Hz CROSS TALK-58dB 

SENSITIVITIES: Disc Mag. 2-5mV. Ceramic 35mV. Radio 120mV. Tape 120mV. 
REAR PANEL 8OCKET8 ARE FOR 3 PAIRS OF INPUTS (1) P.U. (2) Radio. 
(3) Tape Amp. Plus pair for tape recorder signal take off and 2 pairs for speaker 
connections. 



RSC G66 Ml 



+6 Watt HIGH QUALITY 
STEREO AMPLIFIER 



Individual Ganged Controls. Bass, 
Treble, Volume and Balance. Printed 
circuit construction employing 10 
Tr&nslstors plus Diodes. Output rating 
I.H.F.M. Frequenoy range 20-20,000 c.p.s. Bass Control ± 12dB. Treble Control 
± lSdb. Selector switch for P.U. or Tape/Radio. For loudspeaker ontput impedances 
of 3 to 15 ohms. For standard 200-2S0v A.C. mains operation. Attractive Black and 
Silver finished metal facia plate and matching control knobs. 
COPMLETE KIT OF PARTS INCLUDING FULLY WIRED PRINTED CIRCUIT 



and comprehensive wiring diagram and Instructions. ^P 1 " 5 

40p. 

£13.99 



Carr. 40p. 
Or FACTORY BUILT IN TEAK VENEERED CABINET 
as Illustrated or dep. 88 and 8 monthly payments 81-60 
(Total 816 50). 



FANE 807 HIGH FIDELITY LOUDSPEAKER 



A toll range 8in. 10 watt unit tor excellent sound quality. In 
snltable enclosure. Oast chassis Roll P.7.0. eons surround and long 
throw voice coll to achieve very low fundamental resonance of 
SO o.p.s. Tweeter cons is fitted to extend high note response. 
Frequency range 25 Hi to 15 KHi. Gauss 10,000. /"> Cfi 
Impedance 8 or 8-16 CI. STATE WHBX ORDERING tJ-JU 




R.S.C. TA12MKIII 

6-5 + 6-5 WATT 

STEREO AMPLIFIER 

TRAH8I8TORISED, SOLID STATE CONSTRUCTION 
HIGH FIDELITY OUTPUT OF 6 5 WATTS PER CHANNEL 

Designed for optimum perlormance with any crystal or ceramic Gram. P.U. cartridge- 
Radio tuner. Tape recorder etc. -A- 3 separate switched input sockets on each channel 
-A- Separate Bass and Treble controls -Ar Slide Switch for mono use -fc- Speaker Ont- 
put 3-16 ohms ic For 200-230-.-. A.C. mains -Ar Frequency Response 20-20.000 c.p.s. 
-2dB * Harmonic Distortion 0-3% at 1.000 c.p.s. Hum "and Noise - 70dB + Sen- 
sitivities (1) SOmV (2) 400mV (3) lOOmV. Ontput rating l.HJ?.M. * Handsome 
finish Facia plate .* Knobs. 

COMPLETE KIT OF PARTS WITH FULL f\C. KtV^urt. Factory built with 18 mths 
WIRING DIAGRAMS & rNSTRTJCnOHS."- ' * Jw 40p. giarantee £| Q'50 or 

Dep. £3 and 9 mthly pymts £2-15 (Total 422 -35). Or In Teak veneer housing rtl 
Dep. £8 4 9 mthly payments £8.55 (Total 885.95). Send B.A.E. for leaflet *■*■* 



HI-FI SPEAKER ENCLOSURES 

Modern design. Teak veneer finish. Acoustically lined. 

All sizes appro*. Carr. 30p. per enclosure /P.IF 

IBS Size IS x 11 x 91n. Pressurised. Gives LJ JJ 

pleasing results with any Sin. HI-FI 'speaker. 

8E8 For optimum performance with any 81n. ff\ • A / 

HI-FI "speaker. 81ze 22 x 15 x 91n. Ported fcw ~ * 

SE10 For outstanding results 8E12 For exclnt prfmnce with 12ln 
with lOin. Hi-Fi 'spkr XAJJA HI-FI speaker and Tweeter. X1.U7 
Size 24xl6xl0in. P'td. fcW , #t size 26 x 16 x 10|in. i/'O/ 



AUDIOTRINE HI-FI SPEAKER SYSTEMS 

Consisting o! matched 12in. 11,000 lino 15 Watt 16 ohm 
high quality speaker, cross-over unit and tweeter. Smooth 
response and extended frequency range ensure +m -Tr- 
■nrprisingly realistic reproduction. £, J ' / J 

OR SENIOR 15 WATT INC. £6*75 n— 30d 
HF126 15,000 LINE SPEAKER carr.35p 




AUDIOTRINE HIGH FIDELITY LOUDSPEAKERS 

Heavy construction. Latest high efficiency ceramic 
magnets. Treated Cone surround. "D" indicates 
Tweeter Cone providing extended frequency range 
up to 15,000 c.p.s. Impedance 3 or 8-15 ohms. 
PLEASE STATE CHOICE. Exceptional perform- 
ance at low cost. 

HF801D 8- 8W £2-71 HF120D 12" 15W £4-75 
HF102D 10- 10W £33 40 HF126 12" 1SW £5 50 
HF120 12" 15W £4-25 HF126D 12" 15 W £5 90 



f?3 



5**» 



R.S.C A 1 1 HI-FI 12-14 WATT AMPLIFIER I 

PUSH-PULL OUTPUT. Two input sockets with sep. 
vol. controls for mixing. High sensitivity, 6 valves. Bass 
and treble controls. Response ± 3dB 30-20.000 c/s. 
Hum level -60dB. Sensitivity 40 millivolts. Fot 
Crystal or Ceramic PUs. High Impedance "mikes". 
For Musical Instruments etc. 
Std. AC mains. For 3 i If. ohm spars. Complete kit. Full f I n Cfj 
instructions and point-to-point wiring diagrams. Carr. 60p »'" W 
SAE for leaflet. Twin handled metal cover 81.76 

Factory built 814.75 or Dep. 83 and 9 mthly pymnte of 81.60 (Total 817.40.) 



SPECIAL 

HI-FI OFFER 



WHARFEDALE SUPER 
LINTON SPEAKERS 

Teak Finish /"IA.7II PAIR 
Matching Pairs ww '"' carr. f. 



* DEMONSTRATION FACILITIES AT ALL BRANCHES 



w* 



*«« 



R.S.C. TA6 6 Watt HI-FI 
SOLID STATE AMPLIFIER 

200-860v. A0 mains operated. Frequency Re- 
sponse 30-20,000 c.p.e. — 2dB. Harmonic Distor- 
tion 0.3% at 1,000 c.p.8. Separate Baas and 
Treble 'lift' and 'cut' controls. 3 input sockets for Hike, Gram, Radio or 
Tape. Input selector switch. Output for 3-16 ohm spkrs. Max. sensitivity 
6mV. Output rating I.H.F.M. Fully enclosed enamelled case, 9J X 2J x 
5 t ln. Attractive brushed Bllvcr finish facia plate 10} x 3}ln- and matching 
knobs. Complete kit of parte with full wiring X"l Cft n» inr, 

diagrams and instructions, fc # OU **"■ 4U P 

OB FACTORY BUILT WITH IS MOUTHS' <JUARA¥TEE £9*75 



R.S.C. PLINTHS 



Superior Solid Karoral 
Wood Construction 


for 
Record 


WITH TEAK SPABEHT 
PLA8TIC COVER 


Playing 
units,, 
cut for 
Garrard 
1025, 2023, 
3000, AT60, 
SP26etc. 
£3-15 
£6-30 




Four fully wired units ready to 
'plug in'. 

• SUPER 30 AMPLIFIER (15 + 15 
watt) in veneered housing 

• GARRARD SP25 MK III Turn- 
table on Plinth with cover 

ic GOLDRING CS90 Ceramic Pick- 
up Cartridge with diamond stylus 

• PAIR OF STANWAY II Speaker 

sSalTotal^ce £79-80 

Terms: Deposit £12 and 9 monthly 
payments £855 (Total £88-95). 

• Super 30 Amplifier (15 + 15 watt) 
in veneered housing 

ir Goldring GL69 II Transcription 
Turntable on Plinth as illustrated 

■A- Goldring Magnetic P.U. Cartridge. 

-fa Pair of Stanway II speaker units. 
Special Total OAfl nr Cam 

Price tob'/D £lso 

Terms: Deposit £14 and 9 monthly 
payments £10-53 (Total £113-55). 



IGH^FKDELITY §T|£E0 Pj?£0\ 




• TA12 AMPLIFIER 
6-5 + 6-5 watt in veneered 
housing 

• GARRARD SP25 MK m Player 
unit on Plinth 

• GOLDRING CS90 Ceramic P.U. 
Cartridge with diamond stylus 

• PAIR OF DORCHESTER 
Loudspeaker Units 

Special Total Price 
Or Deposit £7-15 and 
9 monthly payments , 
£6 35 (Total £64-30). C9XX - £I "25 
Trans. Plastic Cover £3-15 extra. 



£58 



Matching as recommended for optimum performance. Send 
S.A.E. for coloured brochure showing other money-saving offers. 
Package prices apply providing all individual units are purchased 
from any branch within 3 months. See leaflet. 



ACKAGE AS ABOVE but with 
rd 3000 Autochanger and Sono- 
9TA Ceramic Car- 
tridge in lieu of SP25 
and CS90 

Carr. £1-25 
Or Deposit £6 and 9 monthly pay- 
ments £5-70 (Total £57-30) 
Trans. Plastic cover £3-15 extra. 



£51-75 



HIGH FIDELITY SPEAKER UNITS 

Cabinet* lateit itjle Satin Teak veneer. AcooiticaUy lined 
tor ailed acotutic damping. Potted where appropriate. Credit 
termi available. 

DORCHESTER (H[ us t r ated) Size I6xllx9in. 
appr. Range 45-15,000 c.p.s. 
Rating 8-10 watts. Fitted High 




flux 13 x8in. Dual Cone speaker. gf».jK c '* r - 
Imp. 3 or 15 ohms. Mr ^40p. 

STANWAY II size 20xl0fx9|in. approx. 
Rating 10 watts. Inc. 13 x Sin. speaker with 
highly flexible cone surround, long throw voice 
coil and 10,000 line magnet. High flux tweeter. 
Handsome Scandinavian design cabinet. Range 
35-20,000 c.p.s. Imp. 8 ohms. Gives smooth 
realistic sound output. See 'package /IT, or 
offers' for illustration. "' **' 



rtSMSmn^ 



'YORK' HIGH FIDELITY 
3 SPEAKER SYSTEM 

• Moderate size only 25 x 1 4 x lOin. 

• Response 30-20,000 c.p.s. Impedance 15 ohms 
-A* Performance comparable with units costing 

considerably more. 
Consists of (1) 12in. 15 watt Bass unit with cast 
chassis. Roll rubber cone surround for ultra low 
resonance, and ceramic magnet. (2) 3-way quarter 
section series cross-over system (3) 8 x 5in. high flux 
middle range speaker. (4) High efficiency tweeter, compute 

(5) Appropriate quantity acoustic damping material. *U . 

(6) Handsome Teak veneered cabinet. (7) Circuit and 
full instructions. Terms: Dep. £4-50 and 9 monthly 
payments £2-25 (Total £24-75). Carr.ssp 

DEMONSTRATIONS AT ALL BRANCHES 



i 



£22 



AUDIOTRINE A55 HIGH QUALITY STEREO SYSTEM 



5+5 WATT OUTPUT 
Garrard 5200 Changer with low 
mass pick-up arm and Stereo Car- 
tridge. Controls: TREBLE, BASS. 
VOLUME, STEREO, BALANCE. 
Operation on 200-250v. A.C. mains. 
Output rating I.H.F.M 
Luxurious Teak Veneer Finished 
Cabinets. Transparent plastic (tinted) 
cover included for main unit. Silver 
finished facia plate and matching 
control knobs. 




AIR OF LOUD- 
PEAKER UNITS 



incorporating high flux 8in. 5in. 

speaker. Size approx. 13 x 7| 

Sfins. 

PRICE COMPLETE 

ONLY 

Carr. £1 25 
Terms: Deposit £5-50 and 9 monthly 
payments £4-50 (Total £46) 



£42 



RSC TRANSFORMERS. LE CHOKES and RECTIFIERS 



FULLY GUARANTEED. Impregnated and Interleaved where neceuary 



A REALLY SURPRISING STANDARD OF QUALITY IS OBTAINED F ROM THIS COMPACT LOW PRICED SYSTEM 

R.S.C. BATTERY/MAINS CONVERSION UNITS 

TYPE BM1. An all-dry battery 
eliminator. Size 5} x 4J x 2in. 
approx. Completely replaces bat- 
teries supplying 1 -5v. and 90v. where 
A.C. mains 200/250v. 50c/s is 
available. 

Assembled £3*50 

ready for use 



Primaries 200-850v. 60o/i. Screened 
MIDGET CLAMPED TYPE '2 J x 2| x 2 i in . 

350v., 60mA, 6.3v. 2a 99p 

2B0-0-250V., 60mA 6.3v 2a £105 

FULLY 8HKOUDED UPEIGHT MOUNTIHG 

2SO-0-250r. 60mA, 6.3 v. 2a., 0-S-6.3v. !ia. £1-40 

200-0-250V. 100mA, 6.3v. 4a., 0-5-6. 3v. 3a. £2-20 

300-0-SOOv. 100mA, 6.8v. 4a., 0-5-6.8v. 3a. £2-80 
300-0-300v. 130mA, «.3v. 4a., c.t., 8.3v. la. 

For Milliard 510 Amplifier (2-46 

350-0-350v. 100mA, 6.3v. 4a., 0.5-6.3v. 3a. £2-80 

3B00-350T. 150mA, 6.3v. 4a., 0-5-6.3v. 3a. £2-65 

425-0-425v. 200mA, 6.3v. 4a., c.t., 5v. 3a. i4-95 
425-0-425V. 200mA, 6.3v. 4a., 6.3v. 3a., 5v. 

S» «6-10 

450-0-4r.0v. 250mA, 6.3v. 4a., c.t., Bv. 3a. £5-50 
TOP SHROUDED DROP-THRO' TYPE 

250-0-250V. 70mA, 6.3v. 2a,, 0-5-6.3v. 2a. 41-85 

250-0-250v. 100mA. B.3v. 3.5a. £1 -55 

2D0-0-25Ov. 100mA, 6.3v. 2a., 6.3v. la. . . £1-60 




350-0-350v. siin a. 6.3 v. 2a., 0-5-6.3V. 2a. £1- 65 
2o0-0-250v. lOOinA, 6.3v. 4a., 0-6-8.8v. 3a. £2-80 
300-0-300v. 100mA, 6.3v. 4a„ n-5-fl.3v. 3a. £2- 80 
300-0-300v. 130rnA, 8.3v. 4a., 0-B-8.8V. la. 

Suitable for Milliard 510 Amplifier £2-80 

350-0-350V. 100mA, 8.3v. 4a., 0-5-0. 3v. 3a. £2-20 
350-0-350V. 130mA, f..:iv. 4a., o-.-.-fi.3v. 3s.. £8-80 
FILAMEHT or TRAHBI8T0R POWER PACK 
Type* 6.3v. 1.5a. 49p; 6.3v. 2a. 64p; 6.3v. Sa. 7«p; 
6.3v. 6a. £1-80; 13t. la. B5p; 12». Sa. or 24v. 
1.5a U-85.-0.9-lKv.Iia.tl -10: 0-12-2S-42v.2a. £1-76 
CHARGER TRANSFORMERS 0-9-lBv. lju, 99p; 
21a. £1-10; 3a.£l-B6; Ba.U-45: 6a. £l-«6: 8a. £2-00 
AUTO (Step UP/itep DOWKI TRAK8FORMER8 
0-110/120v. 200-230-250V., 60-80 watte £1-10; 
ISO watte, £1-90 250 watts £8-75: 600 watts £6-76. 
OUTPUT TRASSPORMERS 

Standard Pentwle 5,000 or 7,000 n to 3 CI 60p 
PiiBh-Pull 8 watts EL84 to 3 O or 15 fi . . 88p 
Posh-Pall 10 watts 6V6, ECL86 to S, B, 8 or 

16 a £1-87 

Posh-Pull EL84 to 3 or IB fj 10-12 watU . . U-85 
Posh-Pall Ultra Linear for Mullard 610. etc. £2-80 
Pasb-Pull 15-18 watts, eectlonally wound 

6L6. KT66, eta, for 3 or 15 CI £l-9» 

Pasb-Pull 20 watt high quality sectlonally 

wound EL34, UL6. KT66 etc to 3 or 16 Cl £3 80 




Complete kit with 
diagram. 



£3 



8M0OTHUG CHOKES 

160mA, 7-10H, 260 Q 70p; 
100mA. 10H, 200 CI 80p; 
80mA, 10H, 860 fi BOp; 
60mA, 10H, 400 Q 25p. 

m miim 

RECTIFIERS 
F.W. (Bridged) 

AU 6/12v. D.C. 
Output. Max. 
A.C. Input 18v 
la. 2Sp,2a,85p, 
Sa. 50p, 4a. 85p, 
6a, 80p. 






BRADFORD BLACKPOOL (agent) BIRMINGHAM DARLINGTON DERBY 
EDINBURGH GLASGOW HULL LEICESTER LEEDS LIVERPOOL LONDON 
[MANCHESTER MIDDLESBROUGH NEWCASTLE-ON-TYNE NOTTINGHAM SHEFFIELD 

BEE NEXT PAGE FOR TERMS OF BUSINESS, ADDRESSES etc. 



671 



. 



THE SOUND 



OF QUALITY 






TWIN TURNTABLE UNIT 
WITH MONITORING FACILITIES 



HI-FI CENTRES 
LTD. 



SEPARATE VOLUME CONTROLS 1 

PLUS TREBLE & BASS CONTROLS 
MICROPHONE SOCKET WITH 
ASSOCIATED SWITCH & VOL. CONTROL 



DISCOTHEQUE CONSOLE ffiC 

___■_ ■JT_, FG1/2 1 - ou 



SEND S.A.E. 
FOR LEAFLET 



Terms: Deposit £l I and 9 monthly 
payments of £6'70 (Total £71-80) 



Incorporating twin Garrard SP25 Mk. Ill 
turntables and Goldring CS90 Ceramic Car- 
tridges with diamond stylii. 

Size approx. 36" x 6±" X 15" 

Black Rexine covered Cabinet with lid. 



ig^BASS REGENT 

50 WATT AMPLIFIER 



DISCOTHEQUE EQUIPMENT 

-SAVINGS ON PACKAGE OFFER 



50 WATT SPEAKERS 






A powerful high quality all- 
purpose unit for lead, rhythm, 
bass guitar, vocalists, gram, 
radio, tape. Peak Output rating. 
Loudspeaker unit optional hori- 
zontal or vertical mounting. 
•ft Two extra heavy duty 12in. 

Loudspeakers . 
ir Four Jack inputs and two 
Volume Controls for simul- 
taneous use of up to four 
pick-ups or "mikes". 
Base and Treble controls. 
Send S.A.E. for leaflet. Credit 
Terms Deposit £16 and 9 
monthly payments Ot^A 
of £5-75 (Total j£Q(J 



£67-75) 



Carr. £1 50 




(1) FAL FG1-2 Console 

(2) 100W Power Amplifier 
|(3) Pair High quality Head- 
phones 

| (4) Matching Microphone fitted 

to H/phones 
'(5) Pair 50W Speakers cabinets 

black rexine covered 



H/PHONES 
MICROPHONE 



Terms: Deposit £20 and 
£14 34 (Total £14906). 



INTURNTABIE 
. , WITH PRE-AMP 
9 monthly payments of 



TOTAL COST OF ALL 

ILLUSTRATED 

UNITS 



£132 



DISCO/GROUP EQUIPMENT PACKAGE OFFERS 



30 WATT HI-FI 
AMPLIFIER 



FOR GUITAR, VOCAL or 
INSTRUMENTAL GROUP 

A 2 or 4 input, 2 vol. control 
Hi-Fi unit with Separate 
Bass and Treble controls. 
Current valves. Peak output 
rating. Strong Rexine cov- 
ered cabinet with handles. 

Attractive black/gold P.V.C. facia. Neon indicator. For 
200-250v. A.C. mains. For 3 or 15 ohm speakers. 
Send S.A.E. for leaflet. 
Terms: Deposit £3-70 ONLY 

and 9 monthly pay- 
ments of £2-10 (Total 
£22-60). 



£19-95 

Carr. 65p 



F.A.L. PHASE 50 Mk II AMPLIFIER 

PAIR PANE POP 25(2 25W L/8PEAKEB8. 

FAL PHASE 50 Mk II AMPLIFIER 

PATH FANE POP 80 L/8PEAKER8 OR 
PAIR L12/26 Cabineted Speaker.. 

FAL. PHASE 100 AMPLIFIER 

PAIR LI 29 SOW L/8 In cabinet". 

FAL PHASE 100 AMPLIFIER 

4 FAXE POP B0 L/3PEAKER9. 



Terms: Deposit £5-50 and 9 
monthly payments ol £4-72 
iTntal 147B8). 

Terms : Deposit £10.50 and 9 
monthly payments of £5 
(Tout 145-50) 

Terms: Deposit CCS and 9 
monthly payments of £11-62 
(Total 1189 58). 
Terms: Deposit £15 and 9 
monthly payments of £10-52 
(Total 110950). 



PACKAGE PRICE 

£44 r 

PACKAGE PRICE 

£49»S0r 

PACKAGE PRICE 

*l 18^00 

PACKAGE PRICE 

/QQ --" a!T - 
mww fj.60 




R.S.C. AI0 30 WATT ULTRA LINEAR 

III CI AM PI IFIPR Highly sensitive. Posh-Poll high 
ni-n HnrLintn ootpot. Ham level— 70dB. Response 
±3dB 30-20.000 c/s. All high gTade components. Valves EF86, 
EF86, ECC83, 807, 807, QZ34. Separate Bass and Treble Controls. 
Sensitivity 38 millivolts. For High Impedance microphones. 
For Olabi, Schools, Theatres, Dance Halls, Outdoor Functions. 
etc. For Electronic Organ, Guitar, String Baal, etc. Gram, Radio 
Tape. Two separate inputs with vol. controls permit soch as "mike" and Pick-op etc. to be osed 
for mixing purposes. 200-260 v. 00 c/s A.C mains. For 3 and 15 ohm speakers. Com- £15.75 

Can. 63 p 



plete Kit of parts with wiring diagram and Instructions. Twin-handled perforated 

11.90 Or factory built with EL34 output valves and 12 months' guarantee for £19-75 

TERMS: Deposit It and 9 monthly payments of 12-10 (Total £22-90). Send S.A.E. for leaflet. 



MINIMUM 12 MONTHS GUARANTEE, LABOUR & MATERIALS (Excl. Valves) ON ADVERTISED GOODS 



cjsUZS 



PHASE 50 Mkll 



50W AMPLIFIER 
OUTPUT 

50 Wi.it- (Music) 
40 „ R.M.8. (Cont.) 
100 „ (Peak) 

£33-50 




£t t¥> 



PHASE 100 

I00W AMPLIFIER 
OUTPUT 

100 Watts (MUSIC) 
70 „ R.M.8. (Cont.) 

I.H.M.F. Output rating. 

£61*95 

Carr. 88p ^^^l__^s»y — "- '" -^ss^a^a^aBaP Carr. 70p 

Terms: Deposit £8 and 9 ^H ^_^^s^a^^BBB"^*^^^^^ Terms: Deposit £12 and 9 

monthly payments £3-50. ^Hfca^a^fl wH^^^^^ monthly payments lfl-25. 

Total 187-50. ^^^^"^ Total 168-25. . 

SOLID STATE, ALL SILICOK TRAH8IBTOR8 * Protective circuitry In case of overload or short circuiting of output- 
* Frequency Range 80-20,000 c.p.a. ■4r 4 Separately controlled inputs for mixing: plus master volume control. 
-*■ Individual Baas and Treble Controls. -* Suitable for any loudspeaker combination between 3 4 SO ohms. 

-A> Cabinet covered In black rexine. Brushed silver finish metal facia, with black lettering. Matching control knobs. 
For Clubs, Discotheques, Hotels, Restaurants, Schools, Theatres, etc. For Vocal * Instrumental Groups, Gram., Radio, 
or Tape. Send 8.A.E, for leaflet*. 4 



672 




CABINET LOUDSPEAKERS 



L13 8-10 WATTS 

Incorporating high flux 13 

watt loudspeaker. Available with 

IS ohm. impedance. (State when 

ing.) Cabinet finished in 

Teak or 

Afrormosia Veneer. 



wnen 

£5 



K'ai 



:■ s-io ■ 1 ir 

i 3 or j ■ M ™ 



2/25 25 



WATTS 



•S wati heavy duty 
Ifiuhm&lS" x in* x 
Rexine/YjnuUr Itnhb- Snitabt 

heques. Club*. 8V hm 

etc.. 



Terms: Deposit £3 ami P 
payment.- fl 
Total £12) 



B4/100 100 WATTS 



Fitted four extra heavy duty 1 2" 14,000 Gauss 50 watt speakers for 
conservative rating of 100 watts. Impedance 15 ohms. Cabinet in }" 
chipboard with centre reinforcement back to front. Rexine/Vynair 
covered. Acoustically filled and pressurised 27" • 27" 14" approx. 
Ideal for base guitar or Electronic organ. PCC (Carr. 

Or Deposit £8 and 9 monthly pavments £5-90 T Jl| I £1-50) 

(Total £61-10). • v - uu 




L125 50 WATTS 

Incorporating two 12" 50 
watt 14,000 Gauss extra 
heavy duty loudspeakers for 
conservative rating of 50 
watts. Impedance 8- 1 5 ohms. 
Sturdy pressurised cabinet 
in i" chipboard. Rexine/ 
Vynair Covered 31" V 20" 
'-. 16" approx. Suitable 
Vocal or Instrumental 
Groups. Bass Guitar or 
Electronic Organ, etc. For 
use in Disco- 
theques, Clubs, 
etc. 
(Carr. £1-50) 




etc. ror 

£31 




FAL DUO 100 

Kni|U.vil.ff 1*11 KAKK CUES- 

I'KNDO I-' - 100 wall. -up<r 

cltklellt, hipii flux, llitfh power, 

full rauirr «pi-aker«. i;au-- 30.000. 

IH.TBA H1CH SENSITIVITY. 

Ideal tor Vocalist! and Instrumental 

Oronps. 

PMqneMj Range no— ifi.ooor.p.-. 

Impedance n ohms. 

Cabinet cuiiotructed in heavy j" 

Clilphonr'l Mid cover*! in black 

Rexine ami u learin g shade .it 

Vyualr with alum 

Attractive design. 

Sire JKTX 191- X15J* 

approx . 

Conservatively rated 

at 100 watts. 



lniuiu inn 

£63 



Or Deposit £4 and 9 monthly payments £3-35 
(Total £34-15). 



Tirni- DepoaU £9 and 9 
(Tntul Credit Price £69-30) 



(Can 
ullily payment! 



ape £1 -SO) 

"( £870 



ALL FANE LOUDSPEAKERS GUARANTEED 2 YEARS 



EUa'POP' 25/2 LOUDSPEAKERS 

12in. 25 Watt Dual Cone 1 5ft (for uses other than Base Guitar or Elec- 
tronic Organ), or Dep. £1 and 9 mthly payments 75p (Total £7 75). 



£675 



COLUMN 
SPEAKERS 



IDEAL FOR VOCALISTS AND PUBLIC 

ADDRESS 

All types 15 Ohms covered in Rexine an'. 

Venair 

TYPE C4100 IS ALSO SUITABLE 

FOR BASS GUITAR OR ELECTRONIC 

ORGAN 

G48S 25-30 WATTS I 

Fitted four 8" high flux 8 watt 

speakers. Overall size approx 

48" - 10" 5". 

Terms: Dep £3 

and 9 monthly 

payments £2 

(Total £21) 

Carr 50]- 



£17-75 



G412S 50 WATTS 



Fitted four 1 2" I 1 .000 line 1 5 watt speakers 
Overall size approx 56" 
14" 9". Terms: 

Dep. £4 and 9 monthly 
payments £3 (Total £31) 



I J ^ .III >|lt.iMi ». 

£27-50 




: vx Hon i.y 



Carr T.-'P 



G4100100W 

inc. four 1 2" 50 watt speakers 
for conservative rating. 
Extra heavy construction. 
Size approx 58" X 16" • 10" 
Acoustically filled and pres- 
surised. Terms: Dep. £7 SO 
and 9 monthly payments 
£5-45 (Total £56 55) 

Carr. £1 



£50-50 



HeominKU-lvl IW D1SCOTII F.O.UES. 
MKSTAL (JUMPS. 



E31 ULTRA HIGH POWER LOUDSPEAKERS 



ill power ratings are R.M.S. continuous. 2 YEARS GUARANTEE High flux ceramic magnets. Heavy cast chassis. All carr. Iree. 



18 'POP' 100 

RATING I00 WATTS R.M.S. 
I4.'000gauss8/I55l 

mCn Dep. £6 and 9 

•;|| monthly payments 

UU £215. Total £25 35 



15 'POP 1 60 

RATING 

14,000 gaus- 

£1 2-90 



RATING 60 WATTS R.M.S. 

14,000 gauss 8/ 1 5& 

Dep. £3-30 and 9 
monthly payments 
£1 30 (Total £15). 



12 'POP' 50 

RATING 

1 3.000 gaus: 

£10-50 



FOR BASS GUITAR. ELECTRONIC ORGAN. ETC. 



RATING 50 WATTS R.M.S. 

1 3.000 gauss 1551 

Dep. £2 and 9 
monthly payments 
£115. Total £12-35 

Pair suitable all purposes 



R.S.C. Branches listed below 
Branches open all day Sate. 

BRADFORD ,0 North Par ' de «***»££%* 

BLACKPOOL < A * ent > O & C Electronics 
DLH\.i\rUUL 227 Churcn Street 

BIRMINGHAM 30 ' 31 Grc« W««r n Arcade, 
Dinninunrtn Tel. 021-236 1279. Half-day Wed. 
IiFRRY 26 Osmaston Rd. The Spot (Half-day Wed.). 

Tel. 41361 
18 Priescgate (Half-day Wed.). 

Tel. 68043 

EDINBURGH '" Leith St - (H ' ,M %£&57« 

St. (Half-day Tues). 

Tel. 248 4IS8 
Hill I 91 Paragon Streec (Half-day Thurs.). 
^U, - , - Tel. 20505 

LEICESTER " H ' 8h Street (Half-day Thurs.). 
LEEDS 5 " 7 Count y (Mecca) Ar 



DARLINGTON 



GLASGOW 326 Ar «" 



NOW OPEN AT- 

19/19A MARKET STREET 

NOTTINGHAM 

(Half Day Thursday) 



Tel. 56420 

(Half-day Wed.). Tel. 28252 
LIVERPOOL 73 Dale Street (Half-day Wed). 

Tel. 236 3573 



ADVERTISED UNITS are subject 
to the most stringent tests in our 
Quality Control Depot 

ILLUSTRATED LEAFLETS on 

any advertised product available on 
request. 



LONDON 238 Ed * ware Road - w 2 



MANCHESTER 



723 1629 



ilf-da 
60A Oldham Stree 
(Half-day Wed.). Tel. 236 2778 

MIDDLESBROUGH '« Hs&?i!ttSS8! 

41 Blackett S 
TYNE Fenwicks Store) (Half-day 
Wed.). Tel. 21469 

NOTTINGHAM l9/,9A M "*#SS Thurs > 
SHEFFIELD l3 I'S'&'W Street (Castle Harkec 

JncrriCLV Bids.) (Half-day Thurs.), Tel. 20716 




Fl CEKTRE5 ITO. 



HAIL RDERS & EXPORT EM QuTJUES TO : - 
AVDIO HOUSE, HBNCOMNER LANE LEEDS. IS. 
TEHMP C.W.O. or C.O.D. No C.O.D. umler A. Pn-tlage SSn 
extra umler Oi. S0p extra DVW fil "r as looted. Trade supplied. 
S. \.K. please Billien-iuirlex. 

MAIL ORDERS M0ST NOT BE SENT TO SHOPS 



673 




TWO STEREO 
AMPLIFIERS 




0-200-230-250v. 50 Hz 
A.C. mains operation. 
Inputs for magnetic 
Ceramic Pickup, Tape 
Radio Tuner. 



UNEAR 

6 WATTS uuh 



6 

Recomm 



ided Retail Price 



£22 SO 



TECHNICAL DETAILS 

Bass Control ± 12 dB at 40 Hz. 

Trebl e Control ± 12 dB at 14 KHz. 

Sensitivities Mag. P.U. 3-5 m.v. 
into 47K ohm R.I. A. A. Ceramic 
P.U. 35 m.v. into 100K ohm. Tape 
Amp. 100 m.v. into 100K. 

Radio Tuner 400 m.v. Into 400K 
ohm, Crosstalk 53 dB. 

Hum and Noise- 75 dB min. 
vol. -65 dB max. vol. 

Total Harmonic 
Distortion 0-1 per 
cent at 1 watt into 
15 ohms. 



■k Individual Bass and Treble Controls. 
•k Frequency Response ± 1J dB 

27 Hz to 65 KHz. 
•Ar Outputs for 3-15 ohm Speakers. 
■k Stereo/Mono Switch. 
■*• Input Selector Switch. 
• Solid State Circuitry. 
•k Attractive silver finished metal facia 

and matching control knobs. 



TECHNICAL DETAILS 

Frequency Range 20 Hz to 

20 KHz 

Output (per channel) 4 watts 

I.H.F.M. 

Bass Control ± 12 dB at 60 Hz 

Treble Control ± 14 dB. at 

14 KHz. 



■k A modestly priced solid state unit. 

* The Silver Facia with black lettering enhanced by 
matching control knobs, provides a high standard 
of appearance. 

~k Suitable for crystal or ceramic Gram. Pick-up 

cartridges, and Radio input. 
•k A wide range of tone variation is provided by the 

separate Bass and Treble 'lift' and 'cut' controls. 
•k A selector switch permits instantaneous selection 

of Gram, or Radio. 

• Speaker impedances between 3 and 15 ohms are printed CIRCUIT CONSTRUCTION 
suitable. EMPLOYING 10 TRANSISTORS 



fe j ; O 'O o Q 



■■ 



s+s 



Recommended Retail Price 

£17*50 



^ATTS 



0-200-250v. 50 Hz A.C. 
mains operation 



Wholesale and Retail enquires to the Manufacturers 



ALL LINEAR AMPLIFIERS GUARANTEED FOR 12 MONTHS 



INEAR PRODUCTS LTD. .Electron Works. Armlev. Leeds. LS12 3SATel.630126 



PRACTICAL WIRELESS 

ELECTRONIC IGNITION 

SYSTEM 




This Capacitor-discharge Electronic ignition 
system was recently described in Practical 
Wireless and has proved extremely popular. 
We are able to offer the kit in two forms; the 
Standard kit containing the electronic com- 
ponents only, enabling the customer to tailor 
these to his own layout, or the De-luxe version 
containing a ready-drilled roller-trimmed 
printed circuit board and fully machined 
die-cast case with electrical connection block. 
Each kit Is supplied with a custom wound 
transformer, first-grade components and full 
construction details. Suitable for 12V. systems 
only. pos. or neg. earth. All components 
available separately. Case size 4J" a 3J" x 2" 
Complete assembly and wiring manual 2Sp. 
refundable on purchase of kit. 
Price: Standard kit £7 25 post free 

De-luxe £i-75 post free 

Trade enquiries Invited. Mall order only. 

DABAR 

ELECTRONIC 

PRODUCTS 

Ma. LICHFIELD 8TREET, 
WALSALL, STAFFS. WS1 1UZ 
Tel. Walsall 34M5 



4 STATION INTERCOM 




£7.25 



Solve yoar communica- 
tion problems with this 
t-SlatiOD Translator Intercom system (1 master and 
3 Suba). In de-luxe plastic cabinets (or desk or vail 
mounting. Cail/talk/llBten from Hatter to Suba and 
Bubs to Master. Ideally suitable (or Business, Sur- 
gery. Schools, Hospital, Office and Home. Operates 
on one 9V battery. On/off switch. Volume control. 
Complete wita 3 connecting wires each 66ft. and 
other accessories. P. & P. £0.40. 

MAINS INTERCOM 

Mo batteries— no wires. Just ping in the mains 
(or instant two-way, loud and clear communication. 
On oft switch ami volume control. Price 114.40 
P. a P. £0.55 




Same a« 4-8tatlnn intercom tor two-way Inxtant 
communication. Ideal as Daby Alarm and Door 
Phone. Complete with 6«ft. connecting wire. 
Battrry 14p. P. a P. tn.-J.'i. 




£2.99 

Why not boost 
business effi- 
ciency with this increii iblc De-luxe Telephone Ampli- 
fier. Take down long telephone messages or converse 
without holding the handset . A useful office aid. On/ 
oft switch. Volume Control. Battery 14p. extra. 
P. & P. 22p. Full price retunded U not satisfied in 
7 days. 

WEST LOIDOsT DIRECT SUPPLIES (PW.81 
160 KEHBIHQTOsT HIOH STREET, LOaTDOH. W.8. 




U.H.F. TV. AERIALS 

SUITABLE FOR COLOUR AND MONO- 
CHROME 
RECEPTION 
Ail U.H.F. aeri- 
als now fitted 
with tilting brac- 
ket and 4 ele- 
ment reflector. 
LOFT MOUNTING ARRAYS 
7 element 2 25. 1 1 element 2-75. 
14 element 3-25. 18 element 3 -75. 
WALL MOUNTING c/w 
WALL ARM & BRACKET 
7 element 3-25. 11 element 3-75. 14 element 
4-25. 18 element 4 -75. CHIMNEY MOUNT- 
ING ARRAYS c/w MAST & LASHING 
KIT. 7 element 4-00. 11 elemant 4-50. 
14 element 4-75. 18 element S^M. MAST 
MOUNTING arrays only. 7 element 2-25. 
11 element 2-75. 14 element 3-25. 18 ele- 
ment 3-75. Complete assembly instructions 
with every aerial. LOW LOSS coaxial cable 
9np yd. KING TELEBOOSTERS from 3-75. 
LABGEAR all band V.H.F.— U.H.F.— F.M. 
radio mains operated pre-amps 7-50. State 
clearly channel number required on all 
orders. P.p. on all aerials 50np. Aces. 15np 
C.W.O. Min. C.O.D. charge 25np. 

„ BBC— rrv— FM AERIALS 

BBC (band 1) Wall S/D 2 00. LOFT inverted 
X 1 -? 5 - EXTERNAL 'H' array only 3 00. 
ITV (band 3) 5 element loft array 2-50. 

7 element 3-00. COMBINED BBC — ITV. 
S&y&L&ft H-7 3-50. WALL & CHIM- 
NEY UNITS ALSO AVAILABLE. Pre-amps 
from 3-75. COMBINED U.H.F.— V.H.F. 
aerials 1+5 + 9 4-00. 1+5 + 14 4-50. 
1 + 7+14 5-00. F.M. RADIO loft S/D 1-00 
3 element 3-25. 4 element 3-50. Standard 
coaxial plugs 9np. Coaxial cable 5np yd. 
Outlet box 30np. P.p. all aerials 50np. 
Aces. 30np. C.W.O. Min. C.O.D. charge 
25np. Send 5np for fully illustrated lists. 
CALLERS WELCOMED 
OPEN ALL DAY SATURDAY 

K.V.A. ELECTRONICS 

40-41 MONARCH PARADE. LONDON 
ROAD. M1TCHAM. SURREY 

Telephone 01-648 4884 



674 



SLASH PRICES! 



UP TO 



SPEAKERS (KITS AND CHASSIS) p.p. 50p. 

f Prices Per Pair 

Richard Ailan Twin Assembly £1700 

Richard Allan Triple Assembly £28 00 

Richard Allan Super Triple Assembly £32 00 

Wharfedale Unit 3 £20 00 

Wharfedale Unit 4 £26 50 

Wharfedale Unit 5 £30-50 

Goodmans Axlette 8 £12-25 

Twln-Axlette 8 £14-25 

Axiom 10 £15-00 

Axlom201 £21 25 

Axlom301 £30-50 

Axiom 401 £20 00 

Audlom 8P £» ' 00 

AudiomlOP £6 50 

Audlom 51 £1000 

Audiom61 £27-50 

Audiom12P -. £10 50 

Audlom 15P £33 00 

Audiom18P £52 05 

TwinAxiomlO £15 95 

ARU 172 S'S 

TrebaxlOO Kyi! 

Trebax 5K/20XL £14 50 

Mldax £" 05 

Attenuator "75 

XO/950/5000 £14 00 

XO/5000 ■*••• 

Wharfedale 8in.bronze/R5/DD £7-50 

Wharfedale Super 8/R5/DD fi*'? 

Wharfedale Super 10/R5/DD C H'S2 

WharfedaleWMTI matching transformer £150 

Any other make P.O. A. 



STEREO AMPLIFIERS p.p. 50p 

ARMSTRONG521 £44 00 

AMSTRAD8000 £15 00 

H.L.SA707 flS'SS 

TELETON SAQ206B §8*2 

VICEROY VAS70 £42 00 

VICEROY55 • £16-00 

SANSUI full range in stock P.O. A. 

METROSOUND ST20E **•••• 

SINCLAIR 2000 Mkll fif'S 

SINCLAIR 3000 "2 00 

SINCLAIR NEOTERIC £46-00 

SINCLAIR A.F.U "50 

SINCLAIR S60 + 2 Z30,PZ5 £15 00 

SINCLAIR S60 + 2 Z30PZ6 £17-50 

SINCLAIR S60 + 2 Z50 + PZ8 and 

Mainstrans £22-00 

Sonab special offer for personal callers only 



TUNER AMPLIFIERS p.p. 50p 

ARMSTRONG528 SS'88 

ARMSTRONG 525 *™'*° 

RODGERS RAVENSBROOK 5&& 

TELETON CR10T with speakers SS'S 

TELETONF2100 £&'& 

WHARFEOALE 100-1 '28*2 

PHILIPS RH781 S5*2 

GOODMANS MODULE 80 H8"8 

TELETON R8000 with speakers £35 00 

TOSHIBA range P.O.A. 

Sonab special offer for personal callers only 



TUNERS p.p. 50p 

ARMSTRONG M8 £7 75 

ARMSTRONG 523 SS'S 

ARMSTRONG524 "! ?5 

SINCLAIR Pro. 60 iSWUSii £19 ' 50 

RODGERS RAVENSBOURNE FET2 

Chassis £45-00 



Easy to find— 50 yards from (B.R.) 

Stoke Newington Stn. 

67, 149, 247, 73, 76, 243 Buses Pass our 

door. 



607c 



B 

- g l • — -. 

OZ ay v 
l-u- c,T> .h 
_ - i -= c » = 

y o u x o o 

mi i 

si 



SPECIAL 
OFFERS 

GARRARD SP2S Mk. Ill 
GOLORING G800 Superb Plinth 
and Cover. 

SINCLAIR Project 60— Stereo 60 
Pre-Amplifier and Control Unit. 
2 Z30's and PZ5. 2 WHARFEDALE 
Unit 3. List Price £8400. OUR PRICE 
£55. P. & P. £1-75. 



GARRARD SP25 Mk III 
GOLDRING G800 

Plinth and Cover complete 

OUR PRICE £19-50. P. & P. £1-75. 



SEND CHEQUES, P.O., MONEY ORDER, etc. to— 

AUDI®! SUPPLIES 



HEADPHONES p.p. 250. 

Koss PR04AA £22 00 

Koss727B £13 00 

KossK6 £975 

KossESP-6 £34 00 

KossESP9 £53 00 

KOSSKRD711 P.O.A. 

CARTRIDGES p.p. 10p 

GOLDRING G850 £4 00 

GOLDRINGG800 £7 00 

GOLDRING G800E £10 75 

GOLDRING G800/SE £16-00 

SHUREM3D £4-75 

SHURE M445/7/C £700 

SHUREM55E £9 00 

SHUREM75E type 2 £14-00 

SHURE V15type2 £30 00 

SHURE44E £8-00 

SHURE31E £900 

SHURE 32E £800 

SONATONE9TAHCD £160 

AUDIO TECHNICA AT66 £400 

ADC10/EMkll £21-00 



GARRARD ZERO/100 IN STOCK SPECIAL 

PRICE £35-00. 



TURNTABLES p.p. 60p 

GARRARD SP25/Mk. Ill £10-50 

GARRARD 2025TC wllh Sonotone 9TAHC 

Diamond Cartridge £8-50 

GARRARD A70Mk. II £1100 

GARRARD SL65B £13-00 

GARRARD AP76 £1000 

GARRARD SL72B £23-00 

GARRARD SL75B £2400 

GARRARD 401 £2600 

GARRARD SL95B £32-00 

GOLDRING GL75P £3600 

GOLDRING GL75 £2100 

GOLDRING GL69 £20-00 

THORENS TD125 £61-00 

THORENS TD150AB/2 £41-00 

PIONEER PL11 AC complete £3900 

DUAL 1209 £3400 

PHILIPS 202A £52-00 

SONAB IN STOCK 

Connoisseur BDI ch £1300 

Connoisseur DBI P and C £2100 

Connoisseur BDI with SAU 2 P and C . . £31-50 

Connoisseur BD2 SAU 2 ch £24-00 

Connoisseur BD2 SAU2 P and C £31-00 

Any other make P.O.A. 

All prices subject to change without notice 



PW12. 50 STAMFORD HILL, LONDON, N.16. 
Telephone: 01-806 3611 



PERSONAL CALLERS PLEASE NOTE— Cheques are only accepted when accompanied by a Bank Cheque Card (not Barclay Card). 



CASH & CARRY GOODS Sinclair 2000 £24 

Sinclair 3000 £33 

Metre-sound ST20 £27 
Teleton 203 

(Demonstration) £17 
Teleton F2000 

Tuner/Amp. £31 

Alpha F212 £26 

Please add 50p carr. per 
amplifier. Other Ampli- 
fiers — Tuners — Tape 
Recorders etc. Prices on 
application. 



' f ««• e e t e 

SINCLAIR Project 60 

SAVE nearly £7 Normal price £23-90 

Designed for building Into plus 

plinths etc., complete with f4 "7 SOp 
two Z30 Output stages *» ' ' carr. 
(20 watt) and power supply unit. 
Send S.A.E. for full technical brochure. 



This MONTH'S Best Buy 



Q 



8 



AKG K50 Dynamic 
Stereo headphones 

Complete with spare ear muffs. 



I Total 
\ value £10-40 



Our 
Price 



£590 +ft 



Available only from us at this price. Due to entire 
purchase of manufacturer's remaining stock this 
fantastic offer Is open only while stocks last 

* High-fidelity reproduction due to broad frequency response (2O-2O.0O0Hz) 

* Substantially increased stereo effect * Headphones fit the head gently 
and do not shift * Earpieces fit ears snugly (Cardanlc suspension) * Tone 
quality superior to conventional loudspeakers. * Only expensive studio loud- 
speakers can match the reproduction quality of the K50. * Music can be 
reproduced at concert hall volume (I), preserving the lower bass notes and 
brilliant treble tones without causing any strain to the listener. 




GARRARD SP25 
mklll £12*50 p ' us . 50 " 

•fc.it. ju carriage 
Normal price £15-57 
Wired with mains cable and 5ft. 
twin screened stereo cable, 
5 pin din plug. 53p extra- 
AP75 Complete with base and 
cover £25 plus 75p carriage. 

PLINTH AND COVER SUIT- 
ABLE FOR GARRARD RANGE 
£5-25 plus 50p p. & p. 



Replacement Stereo 
DIAMOND STYLI 

8TA 9TA 9TAHC __ 

GP91 ST4 ST9 /Sn 

EV26 GC8 I«/p Mcn 

others on request + I3p p. & p. 

Countdown SPEAKER 

Teak Cabinet 



£12 



plus 3Sp 
carr. 4 Ins. 



A speaker of out- 
standing specifi- 
cations and tech- 
nical merit. Solid 
teak cabinet size: 14" x 10' x 6". 
Originally designed for use with our 
Countdown stereo budget system 
but now available separately. 




PLUGS 



L - LJ . . 



Pack 107 5-Pin Din 2Qp 

Pack 108 3-Pin Din 18p 

Pack 135 i" Jack Zip 

Pack 130 j" Jack Stereo . . 4lp 

Pack 103 Loudspeaker Plug .. ISp 

Pack 100 Phono Plug .. .. tp 

Pack 230 3-Pin Socket . . 2]p 

Pack 236 5-Pin Socket . . 30 u 

Pack 234 Loudspeaker Socket . . Mp 
Ready-made Leads 

3-pin to 3-pin Din .. Up 

3-pin to open end 53p 

5-pln to 5-pin Din Mp 

5-pln to open end Mp 

5-pin to 4 phono plugs .. 93p 

Speaker lead Din to spade 12ft Mp 
Extension lead Din plug to socket 
12ft I5p 

All leads approx. 6ft. In length. Post 
free, by return. 



EMI 20w matched 
loudspeaker set 350 

Frequency range: ^7.IM 

20 to 20,000Hz. «.i*au 

Normal price £13 plus 40p p 4 p 
EMI 10w matched 
loudspeaker set 450 
Our price £3-75 Plus S5p. P- & P. 
134" x8t" elliptical loud- 
speaker and indepen- 
dent high frequency 
units with associated 
crossover network. Fre- 
quency range 55 to 
13000Hz. The cone of 
the bass unit has a sur- 
round designed for high 
travel giving freedom from distortion 
when operated at low frequencies. 
EMI 14A/770C JM A.KA plus 50p 
Base Speaker ft'* «W P 4 P 




Magnetic cartridges 
Diamond r- * nn 
styli £400 

plus 13p p. & p. 
Today's value £6. 
Stylus replacement 
can be carried out without removing 
cartridge. Styli £2-13 + 13p p. & p. 



cm 



SONOTONE 
Cartridge ... 

(Fitted Diamond Styli) 
( Ceramic) list price £4-10 
Sensitivity: fftEA 

9TAHC 55mV/em/«ec X.£.'0\3 

rms minimum at 45° at plus 
1.000Hz measured on 13p 
Oecca SXL2057 p. A p. 



Ronette 105 Stereo cartridge (Sapphire 78 Diamond LP) £i-2$+i3p.p.*.p. 



J. J. FRANCIS 

(WOOD GREEN) LTD 
123 ALEXANDRA ROAD, H0RNSEY, 
LONDON, N.8. Tel: 01-888 1662 



A true bargain 
by Post: 




The 

famous 
PA 263 

plus 

heatsink/ 
pc board 
for £1.75! 



The PA263 monolithic audio 
power amp. provides 3.5W rms, 
10W peak, to a 16 ohm load. 
Ideal for mono or stereo 
players, tape, disc or intercom 
amplifiers, FM or AM receivers, 
Op. Amp. boosters etc. 

Now we supply it complete with a specially designed heavy duty 
pc board ready drilled for PA263 and up to 12 other components 
(not supplied) a II ready for soldering. No other heatsink is 
necessary. ONLY£1.75 COMPLETE, | p&p£0.15.Orstereo£3.50 
plus £0.15 p&p. Delivery by return. 

FREE4-PAGE PA263 DATA SHEET PLUS DESIGN INFORMATION 
WITH ALL ORDERS. 

Jermyn Industries, 1 1~~ m n /l VAr\ I 

Vestry Estate, Sevenoaks. Kent. JbR IVI T IM 




Newest, neatest 
system ever de- 
vised for storing 
small parts and 
components : re- 
sistors, capacitors, 
diodes, transis- 
tors, etc. Rigid 
plastic units, in- 
terlock togethe 
in vertical and 
horizontal con 
binations. Tran 
parent plast 

drawers have label 
slots / removable 
space dividers. Bu 

any size cabinet for wall, bench or table top. 
SINGLE UNITS (5'x24/"x2±") £135 Do 
DOUBLE UNITS £2-25 Dozen 
TREBLE (3D) £2-35 for 8 

DOUBLE TREBLE 2 draws in one outer case (6D2) £3 65 
for8 extra large size (6DI) £3-30 for 8. 

PLUS QUANTITY DISCOUNTS! Order £5 and over Deduct 5% in the £. Order 
Deduct 7+% in the £. Order £20 and over Deduct 10% in the £. 
arr .- Add 35p to all orders under £5. Orders over £5 P/P/C free. 
r/ tI'i'/H lDeptPW12.l24 CRICKLEWOOD 
BROADWAY. LONDON N.W.2 



DISCOUNT 

PRICES 



£IOand« 



AERIAL BOOSTERS 

We make lour types of Aerial Boosters. 
L46 6-25 U.H.F., 1,12 V.H.F. TV. 
Ill V.H.F. Radio, L10 M/W & S/W. 
Price L45, 113 4 Lll £2-95, L10 £2-45. 

VALVE BARGAINS 

Any 5 -45p. 10=70p: 

ECC82, ECL80, EFSO. EFS6, EF183, 

EF184. EBF89, EB91, EY88, PCC84, 

POC8B. PC97. PCFS0, PCF86. PCL82, 

PCL83, PCL84, PCL85, PL36. PY33. 

PY82. PY800, PY801, 30L15, 30C15, 

6-30L2. 



TRANSISTOR BARGAINS 

We offer the following brand new 
marked transistors for sale. Anv ;V4.0p, 
10-75p:^BC113, BC171. BC1I7," JJC135, 
BC183. BF115-15p, BF184-15P, BF200- 
20p. 

PRINTED CIRCUIT BOARD 

2-8 ins by 4 ins boards complete with 
etching compound and instractlons-40p. 

MAINS DROPPERS 

Three section 33-33-33 Ohms 9p. 



POST 4 PACKING under £l-5p Over «JM0p. S.A.E. for leaflets 
back guarantee If not completely satisfied. 



i all items. Money 



VELG0 ELECTRONICS 

62A Bridge Street, Ramsbottom, Bury, Lanes. 



676 



»a 



no 



Jfc- BAO, ° 

4 bbo, ° 

1 



HOME RADIO (Components) LTD. 
Dept. PW, 234-240. London Rd., 
Mitch am, CR4 3HD. 01-648 8422 



When you think 
of COMPONENTS 
think of HOME RADIO 



POST THIS 
COUPON 
with your 
cheque or 
postal order 
for 70p 



Some things in life are just about inseparable — eggs and bacon, sausage and mash, Tweedle 
Dum and Tweedle Dee! Think of one and you think of the other. That's how thousands of radio 
and electronic enthusiasts think of Components and Home Radio Ltd. When they need the first 
they automatically contact the second. They simply flip through their Home Radio Catalogue, 
locate the items they need and telephone or post their order. 
If you have not yet experienced the simplicity and satisfaction of linking Components and Home 

Radio, why not make a start now? First of all you'll need the catalogue in its 315 pages are 

listed more than 8,000 components, over 1 ,500 of them illustrated. Every copy contains 10 vouchers, 
each worth 5p when used as instructed. 



The catalogue costs 70p including postage 
and packing. Drop us a line or use the coupon 
below. 



., -- "« 




Please write your Name and Address in block capitals. ^^^^V 

Name U\J 

Address 

HOME RADIO (Components) LTD. 
Dept. PW, 234-240 London Rd., Mitcham, CR4 3HD 



24-hour 
Phone 
Service. 
Ring 
01-648 8422 

Ask for 
details of 
our Credit 
Account 
Service. 



The price of 70p applies only to catalogues purchased 
by customers in the U.K. and to BFPO addresses. 




677 



HI-FI DISCOUNT 
WAREHOUSES 



DRIVE-IN CAR PARK 




Rec. Reliil Comet 

STEREO AMPLIFIERS Price Price 

ALBAUA700 34-50 23-M 

ALPHA 212 By Highgate 3675 2495 

AMSTRAD Stereo 8000 Mk 2 .... 27-95 17-9S 

AMSTRAD I.C. 2000 48-95 27-95 

ARMSTRONG 521 59 00 41-71 

DULCI 207M 3200 19-9J 

FERROGRAPH F307 Mk. II (cased) 64-00 45 95 

FERROGRAPH F307 Mk2 metalcase 60 00 42-95 

GOODMANS Maxamp 5400 3791 

LEAK Delia 30 (cased) 6500 51-95 

LEAK Delta 70 (cased) 79-50 93 95 

METROSOUND ST20E 39-50 27- 95 

PHILIPS RH 591 7900 54 95 

PHILIPS RH 690 52 00 MM 

PHILIPS RH 580 29 00 1911 

PIONEER SA500 82-10 41-95 

PIONEER SA700 9800 97-95 

PIONEER SA900 134-10 14 45 

PIONEER Reverberation 45-50 31-91 

REVERBERATION 202W 46-35 33-K 

RANK Rotel 310 45-00 32-M 

RANK Rolel 810 69 00 49-91 

ROGERS Ravenabourne 59-50 42-95 

ROGERS Ravensbourne (cased) .. 6400 47-H 

ROGERS Ravensbrook Mk. II .... 47-50 MM 

ROGERS Ravensbrook (cased) Mk.ll 52 50 M 95 

SINCLAIR2000 35 00 23-71 

SINCLAIR Project 60.2 x Z30PZ5 23-90 11-95 
SINCLAIR PROJECT 60/2 x Z50/ 

PZ8/trans 34-86 23-25 

SINCLAIR PROJECT 605 29 95 MM 

SINCLAIRAFU 5-95 «•« 

SINCLAIR Neoteric 61-95 43 95 

SINCLAIR 3000 45 00 3110 

TELETONSA0206 32 50 13 95 

TELETONGA101 37-50 2150 

VOLTEXIOOw. Stereo Discotheque. 

8 electronically mixed inputs 185-00 139 00 

WHARFEDALE Linton 60 00 47 M 

All the above take both ceramic and magnetic 
cartridges. 

TUNERS 

"ARMSTRONG 523 AM/FM 54-22 39 95 

•ARMSTRONG 524 FM 42-17 30-91 

ARMSTRONG M8 Decoder .. 9-50 7-70 

•DULCI FMT.7 FM 25-10 19 95 

DULCI FMT.7S Stereo 33 79 27-21 

GOODMANS Stereomax 8007 47-M 

LEAK Delta FM 75-00 58 95 

LEAK Delta AM/FM 89-50 69 50 

PHILIPS RH890 45-30 36 50 

PHILIPSRH691 85-BO 89-95 

PIONEER TX500 AM/FM 75-95 8150 

PIONEER TX900 AM/FM 147-15 118 00 

RANKROTEL320 49-99 39 95 

ROGERS Ravensbourne chassis .. 59-63 46-91 

ROGERS Ravensbrook 43-37 34-95 

ROGERS Ravensbrook (cased) .... 49-39 38 95 

ROGERS Ravensbourne In teak case 64-45 48-95 

SINCLAIR 2000 45-00 34-95 

TELETON GT 101 43-93 JO 95 

All above Tuners are complete with MPX 
Stereo Decoder except where starred. 
TUNER/AMPLIFIERS 

AKAIAA8500 22185 171 90 

AKAI6600 I373J ,UH 

AKAI6300 ,5a-8S MM 

AKAI 6200 91. B 7,-95 

ARENA 2400 90 30 69 95 

ARENA 2600 11130 MM 

ISiK*! 7 ^ ••••••— SI »■« 

ARENA T9000 303-45 285 00 

ARMSTRONG MB Decoder 9-50 7-70 

ARMSTRONG 525 88 65 89 91 

ARMSTRONG 528 105-72 79-S 

GOODMANS Mod. 80, 35w. R.M.S. 91 59 II 95 
GOODMANS Model 110 FM/MW/ 

LW/SW 100W R.M.S 135 00 INN 

LEAK Delta 75 185 00 39 95 

MIDLAND 19/542 49.53 'J7.J, 

PHILIPS 882 with stereo cassette 

_ recorder 96-50 78 15 

PHILIPSRH790 134. 00 79 95 

PIONEER SX770 AM/FM 169-79 125M 

PIONEER SX990 AM/FM 19261 148 95 

PIONEER440 119-82 95 80 

ROGERS Ravensbrook Chassis .. 99-39 81-95 

ROGERS Ravensbrook (cased) .. 108-43 MM 
TANDBERG 1171 comp. with 

decoder 110-00 91-M 

TANDBERG TR200 without decoder 9900 82 95 

•TELETON F2000 .... 51 -50 28 95 

TELETON 7AT20 11975 89 95 

TELETON 10AT1 150w. RMS 160-00 94 09 

TELETON TFS50 79-68 52-85 

Trl-IJSK I£ S5 ° LA MW/LW/FM 88-64 80 95 

TELETON CR55 125 26 74 95 

WHARFEDALE 100-1 139-0O 89 95 




for 
after -sales service 

THROUGHOUT THE U.K. 

Pictured, Service Dept. 
at Clough Rd., Hull 
also at Leeds, 
Stockton, Goole, 
Wakefield, Doncaster, 
Bridlington, Birmingham 
and Edinburgh 



All the above Tuners and Tuner/Amplifiers lake 
both ceramic and magnetic cartridges except Teleton 
F2000 which Takes ceramic only. All include MPX 
Stereo Decoder with the exception ot Armstrong 
where decoder is extra as listed. 

Rec. Retail Comet 

CARTRIDGES '"" *"" 

GOLDRING800 12-55 87S 

GOLDRING 800E 18-16 19 50 

GOLDRING 800 Super E 26-10 15 M 

•GOLDRING CS90 Stereo 5-02 4 10 

•GOLDRING CS91/E 7-53 III 

GOLDRING 6850 6-27 3-91 

EMPIRE 1000ZE/X 60 34 5125 

EMPIRE 9MVE/X 43 00 14 95 

EMPIRE 999TE/X 2509 21 00 

EMPIRE 999SE/X 20-31 16 95 

EMPIRE 999E/X 15-89 12 50 

EMPIRE9M/X , 12 55 10 25 

EMPIRE909E.X 12-37 185 

EMPIRE909/X 9 26 771 

EMPIRE90EE/X 9-56 7M 

ORBIT Magnetic NM 22 .... Special Price 2 95 

ORTOFON SL15E 2862 22 95 

ORTOFON 2 X 15K Transformer .. 700 4 95 

ORTOFON M15E 29 08 23 10 

SHURE M30M :. 7 16 4 54 

SHURE M31E 11-63 a-7t 

SHURE M32E 10-73 8 05 

SHURE M32-3 9-84 7-M 

SHURE M44-5 10-73 7-U 

SHURE M44-7 984 7-1J 

SHUREM-44C 9-84 711 

SHURE M44E 11-63 7-M 

SHURE M55E 12-52 8 95 

SHURE M75G 16 99 1371 

SHUREM75-8 16-10 12 45 

SHURE M75EJ 18-78 14 95 

SHURE M75E 20-57 12 M 

SHURE V1S-11 3935 27 M 

SHUREV15-11-7 37-56 17 H 

Starred cartridges above are ceramic. All others are 
magnetic. 

PICKUP ARMS 

GOLDRING Lenco L7S 13-88 9 50 

GOLDRING Lenco L68 1004 I 50 

SME 3009 with S2 Shell 33-26 24 M 

SME 3012 with S2 Shell 3542 26 45 

TURNTABLES 



The following Turntables are complete with 
base, plinth, perspax cover and cartridge. 
Fully wired and ready lor use. All at special 
prices. 

GARRARO SP25 Mk 111 with Goldring G.8O0 

Special Price £19 85 
GARRARO SP21 Mk 111 with Shura M.44/7 

Special Prlca £22 95 
GARRARO SPH Mk 111 with Shura M.ME 
■ Special Prlca £23 M 

SARRARO AP78 with Goldring S800 

Special Price £38 95 

GARRARD AP78 with Shure M73E 

Special Price £3« 95 
GARRARD 2025 with Sonotona 9TAHC 

._ Special Price £14 M 

GOLDRING 7M/P with GSM 
__.__... Special Price £14 M 

GOLDRING GL75 with G804 special £19-85 
GOODMANS 3025 with G800 ««•« 

Special Price £21 M 



GARRARD SP25 Mk III 15-85 

GARRARD SL65 B 20-48 

GARRARD SL95 B 49 23 

GARRARD 401 39 26 

GARRARD SL72 B 31-83 

GARRARD Zero 100A 56 25 

GARRARD Zero 100S 51-75 



19 58 
13 45 
32 91 

27 41 
23M 

42 M 

41 95 



Rec. Retail Comet 

Ptlct Price 

GARRARD 3500. with GKS Cart. 15 25 10 95 
Base and Cover to fit GARRARD 

SP25, SL55, SL65B and 35O0 . .Special Price 350 

GARRARD 40B 13-34 10 49 

GARRARD AP76 27-85 18 M 

GOLDRING GL69Mk. II 27-60 1f-M 

GOLDRING GL69P Mk.ll 36-21 2S-95 

GOLDRING GL75 40-15 28 95 

GOLDRING GL75P „ 48-76 35 9S 

GOLDRING Covers for 69P and 75P 4-48 3 30 
GOLDRING C99— plinth and cover 

forG99 1105 i-75 

GOLDRING G99 26 89 19 95 

GOODMANS 3025 37-74 21 M 

Mcdonald mp so is 20 10 m 

Mcdonald 610 19-23 1450 

Mcdonald ht 70 2122 17-54) 

McDONALD HT70 Inc. plinth A cov. 30 68 24-M 
Base and Cover lor McDONALD 

MP 60 and 610 Special Price 425 

PHILIPSGA146 30-35 23-M 

PHILIPS 202 Electronic 66 50 49 95 

PHILIPS 308 transcription unit com- 
plete with base and cover 37-60 29-95 

PIONEER PL12A with base 4 cover 48.34 M-M 

THORENS TX25 cover 8 52 4 95 

THORENS TD125 7603 58 95 

THORENS TD125AB 11557 94 58 

THORENS TD150A Mk. II 44-40 MM 

THORENS TD150AB Mk. II 4805 48 25 

THORENS TX11 Cover 4-26 3 56 

WHARFEDALE Linton 35 00 28 95 

8PEAKERS 

BAWModel70 159-50 114 95 

B4.WDM3 6300 46 41 

B4WDM1 38-47 SIM 

CELESTION Dltton 120 28-85 22-95 

CELESTION Dltton 15 38-47 3195 

CELESTION Dltton 25 65 00 44 95 

GOODMANS Minister 24 10 17-45 

GOOOMANS Havant 28 00 21 M 

GOODMANS Msglster 62 50 4195 

GOODMANS Double Maxim .... 33 00 25 95 

GOODMANS Mezzo 3 34 00 22-91 

GOOOMANS Magnum KB 4400 29 95 

GOODMANS Dimension 8 69 00 49 95 

GOODMANS din 20NT kit 12 54 9-M 

KEF Create 22-17 18 00 

KELETRON KN400 2-speaker Sys- 
tem (pair) 16-10 MM 

KN600 3-speaker System (pair) . . 26 86 18 95 

KN800 3-speaker System IS 90 16 95 

KN1100 4-speaker System 20-40 14 20 

KN1600 3-speaker System 25-20 16 95 

KN2100 3-speaker System 30 60 29 M 

LEAK 200 30 19 II 45 

LEAK 300 39 33 23 95 

LEAK 600 49-50 35 95 

LOWTHER Acousta (with PM6) .. 52 50 45-M 

LOWTHER Acousta (with PM7) . . 65-00 54 00 

LOWTHER Ideal Baffle 37-50 32-M 

METROSOUND HFS103 (pair) .... 30 06 19 M 

METROSOUND 202 21-60 15 -M 

PHILIPS RH481 10-60 8 45 

PHILIPS RH482 17-35 14-45 

SINCLAIR Q16 8-95 I 29 

STE-MA 400 24-00 16 M 

TANDBERG TAN 7 28 00 23 95 

TANDBERG TAN 11 19 00 18-25 

TANDBERG TAN 15 4500 M-M 

WHARFEDALE Speakers 

Danton Mark II 19-95 15-95 

Linton Mark II 24 96 19 95 

Melton Mark II 35 00 27 K 

Dovedale 3 45-00 26 95 

Rosedale 65-00 48-50 

Triton (pair) 72-16 42-15 

Unit 3 Speaker Kit 12-53 9-70 

Unit 4 Speaker Kit 1800 12-M 

Unit 5 Speaker Kit 26-00 18 59 



678 



(OVER 1.620 sq. yds.) 




flee. Retail 
Prlct 
CHASSIS SPEAKERS 

GOODMANS Amette8 7 81 

GOODMANS Twin-axiette 8 .... 8-84 

GOODMANS Axiom 201 1445 

GOODMANS Axiom 401 17-88 

GOODMANS Twin Axiom 10 .... 9-86 
GOODMANS Audiom 8P 



10P 5 83 

12P 12-37 

15P 2000 

18P 34 00 

4 50 
100 



Comet 
Prlct 

• 25 

I 95 

10-45 

13 95 

7-50 

4-95 

3-25 
9 50 
16-50 
25 95 
3 25 
5 50 
4-95 

1 50 

2 25 

7-15 



GOODMANS Audio 
GOODMANS Audiom 
GOODMANS Audiom 
GOODMANS Audiom 
GOODMANS ARU172 

GOODMANS Trebax 100 8 60 

AXENT100 690 

GOODMANS Mldax 650 12 95 

GOODMANS Attenuator 3 55 

GOODMANS Crossover Networks 

XO950 5000 975 

GOODMANS Crossover Networks 

XO.950 7 40 5» 

GOODMANS Crossover Networks 

XO5000 2 65 180 

WHARFEDALE 8in.Bronze/RS'OD 4 82 3 50 
WHARFEDALE Super 8'RS'DD .. 8 19 6 75 
WHARFEDALE Super 10RS/OD 11 20 9-St 
WHARFEDALE WMT1 Matching 

Transformer 84 70 

HI-FI STEREO SYSTEMS COMPLETE 

ALBA UA552 45 86 35 50 

ALBAUA662 60 32 46 95 

AMSTRAD Stereo 1000 48 00 36 95 

DECCA Sound 613 70 14 57 95 

DECCA Sound 614 66 55 54 95 

DECCA Sound 1204 89 44 72 95 

DECCA Compact3 119 56 103 95 

FERGUSON3422 84 80 65 95 

FERGUSON3423 114 15 89-95 

FERGUSON 3425 with radio 140 10 108 00 

FERGUSON 3450 with radio 72 40 59 95 

FIDELITY UA2 Music Master .... 44 41 33-95 
FIDELITY UA1 Music Master with 

radio 103 29 79-95 

GOODMANS Module 80 Compact 
System FM/35 watts R.M.S. 

(lessL/S) 16500 129-M 

SPECIAL OFFER 
GOODMANS Max-amp Stereo 
Amplifier. Goodmans Stereo-max 
AM'FM Tuner with Decoder. Pair 
o! Goodmans Magnum K2 Spea- 
kers. Garrard A. P. 76 Turntable 
in base, complete with cover and 
Goldrlng G.800 Cartridge. Beautl- 

fully finished In Walnut 257-13 159 95 

H.M.V. 2404/5/6 with radio 198 00 155 95 

HMV2452 65-65 53 95 

HMV 2450 with stereo radio 134-20 109 00 

MARCONI 4450 with radio 72 40 55 50 

MARCONI 4452 76 00 55 95 

METROSOUND Stereo 1010 com- 

pleto with speakers 79 34 55 95 

PHILIPS 580/481/105 7100 55 95 

PHILIPS GF 823 <7 80 36 95 

PHILIPS GF 824 67 10 52 95 

PHILIPS RF833 87-10 52-95 

PHILIPSGF834 86 40 65-95 

PHILIPSGF417 96 06 69-95 

PYE Black Box Unit Stereo 1022.... 93-45 69 95 

TELETON 2S60F with radio 72-40 5395 

TELETON STP 8-tr.>ck Stereo 

System 54-75 47-00 

ULTRA6405 7700 64-95 



OVER lOOO ITEMS 
LWAYS IN STOCK 

ALL. FULLY GUARANTEED - 
WITH AFTER-SALES SERVICE 

iw, lat«t imxWi la ma—tattmrw* ttaletf earttws 



flee. Retail Comet 

Price Price 

AKAI CR80 8-track stereo recorder 99 95 75 95 

AKAIX200O 1«-95 09 90 

AKAI1800SD 15300 119 00 

AKAI2000SD 28900 2 6 00 

BUSH Discassette DC70 21-19 16 95 

BUSH TP60 Cassette 28 38 23 95 

BUSH TP70 Cassette, battery/ mains 28 91 23 50 

FERGUSON 3245 Twin track 36 70 Z7 95 

FERGUSON 3246 4-track 42 55 32 95 

FERGUSON 3247 4-track 47 95 37 95 

FERGUSON 3248 4-track 53 75 4195 

FERGUSON 3252 4-track 100 52 89 95 

FERROGRAPH7022-tracktapedeck 220-22 185 00 

FERROGRAPH 704/W 4-track tape 

deck 220 22 185 00 

FERROGRAPH 722 256 52 209 00 

FERROGRAPH 702 Dolby 272 25 229 00 

FERROGRAPH 724 256 52 209 00 

FERROGRAPH 722 Dolby 308 55 262 00 

GRUN DIG C200 De Luxe Cassette 38-45 28 95 

GRUNOIG TK 121 twin track 57 90 42 95 

GRUNDIGTK 141 4-track 63 90 47 95 

GRUNOIG TK 146 4-track Auto 68 90 53-95 

GRUNDIG 222 stereo cassette .... 59-85 47-95 

GRUNOIG TK 147 4-track Aulo 95 75 79 95 

MIDLAND TC 144 cassette 18 00 1195 

PHILIPS 2202 cassette 26 90 19 95 

PHILIPS 2204 cassette. battery/mains 32 30 23-95 

PHILIPS 2205 cassette tape recorder 41-60 33 50 

PHILIPS 3302 cassette 2305 17 50 

PHILIPS 4303 new release 40 55 32 50 

PHILIPS 4307 4-track 4780 35 95 

PHILIPS 4308 De luxe 4-track 58-40 43-50 

PHILIPS 44042-track stereo recorder 91-70 19-95 

PHILIPS 4407 4-traek stereo recorder 106-20 85-95 
PHILIPS 4500 4-track stereo tape 

deck 121-65 94-95 

PHILIPS 4408 4-track stereo 134-20 104-50 

PHILIPS 2503 Cassette Stereo 

tapedeck 52 05 41 -K 

PHILIPS 2400 stereo cassette less 

L/S 65-55 56-45 

PYE Cassette Recorder/Radio 9000 

battery/mains «-86 35 95 

TAND3ERG 1841 4-track stereo 

tapedeck .68 00 58 95 

TAND3ERG3021Xtwln track stereo 10700 91-00 

TAND3ERG3041X 4-track stereo.. 10700 M00 

T AN D3ERG 4021 X twin track stereo 174-00 14500 

TAND3ERG 4041X 4-track stereo.. 174 00 145 00 

TANDBERG 6041X 4-track stereo.. 188 00 158 00 

TANDBERG6021X twin track stereo 18800 158-00 

TELETON 8110 cassette 26-75 14 95 

TELETON TC110 cassette battery/ 

mains ••• 2679 18-95 

TELETON TRC130 cassette with / 

VHF/AM Radio. Batt. /Mains, twin 

motors 40-31 27-9S 

TELETON 511 battery/matn« 

cassette 29-50 17 50 

WHARFEDALE Dolby DCS cas- 

sette stereo tape deck 110 00 94 50 



BASES AND COVERS 

GARRARD WB1 Base 3-71 

GARRARD WB4 Base 5-49 

GARRARD SPC 1 Cover 3 60 

GARRARD SPC 4 Cover 4 27 

Soecia- offer of Base and Cover to fit 
GARRARD SP25, SL55, SL65B and 

3500 Special Price 

GOLDRING Plinth 75 8 60 

GOLDRING Plinth 69 8-60 

GOLDRING Covers for 69P and 75P 4-48 
THORENS TX25 (for TD125AB) .. 

THORENSTX11 Cover 

Base and Cover for TO 125 15 04 

SME Plinth System 2000 4136 

MOTORBOARDS only 



8-52 
426 



5 22 



3 25 

4 75 

2 95 

3 75 



4 00 
7 00 
7 00 
3 75 
6 95 
3 75 
12 45 
33 50 
3 25 



OpMdaityto 
«w pubtto from 
t-0 A.M. untM- 

B-30 P.M. MOM. 
1-0 P.M. TOES. 
t-0 P.M. WED. 
t-0 P.M.THUR. 
t-0 P.M. FRI. 
6-30 P.M. SAT. 

Cuatonvsra era 
w e lcome to call ■ 
AmpMsvptriun« 
ffteiHtJM 



COMPLETE HI-FI 
SYSTEMS 

Completely wired mounted 
and ready for use 

flee. Retail Comet 
Price Prlct 

GOODMANS AUDIO SUITE. 
Goodmans Maxamp stereo ampli- 
fier, Goodmans stereomax AMi 
FM Tuner with decoder. Pair of 
Goodmans Magnum K2 speakers, 
Garrard AP76 turntable in base, 
complete with cover and Gold- 
ring G800 Cartridge. Beautifully _ A 
finished In walnut 257 13 169 95 



. 32055 
es) 
Tel. 66132 
•5215 



GOLDRING 705P turntable complete 
with G850 Cartridge. Midland 
Tuner/Amp., pair of Melrosound 
103 Speakers 105 61 69 95 

THORENS TD 150AB Mk II wilh 
TX11 dust cover, SHURE M55E 

Cartridge, LEAK 70 Amplifier, 2 

Wharfedale Dovedale 3 Speakers 234-33 165-95 

TELETON STP 801 Stereo 8 track 
tape Audio system complete with 
speakers *••• 54-75 4800 



GARRARD SP25 Complete with 
base and cover and Goldrlng G800 
cartridge. Teleton 206 amplifier 
and pair of Leak 200 speakers.. 



128 59 72 95 



GARRARD AP76 with base and 
cover with Shure 55E cartridge 
Arena AM/FM and. SW TuneW 
amp and 2 Goodmans Mezzo III 
speakers 229 43 145 80 



GOLDRING GL 75 complete with 
base and cover, G800 Cartridge, 
Wharfedale 100-1 Tuner,Amp 
and 2 Wharfedale Dovedale III 
speake'S 



294 79 183 80 



GOODMANS Module 80 Tuner/ 
Amplifier, Garrard AP76 Turn- 
table with Goldrlng G800 Cart- 
ridge and 2 Goodmans Minister 
Speakers 189-95 133 95 



GOLDRING 705P turntable fully 
wired, complete with Goldrlno 
850 Cartridge. Amstrad stereo 
8000 amplifier and 2 Metrosound 
103 speakers 8100 49 95 

METROSOUND 448 8-track stereo 
play-back unit complete with 
2 HFS 103 Speakers 83-56 70-95 



TAPE RECORDERS AND TAPE DECKS 

AKAM720L 4-track Stereo 83 73 65 95 

AKAI 4000 D 4-track stereo deck . . 89-95 65 95 
AKAI CR 80D 8-track stereo tape 
deck 79 95 59 95 

Complete Prtc« List FREE on rtqusttl 

COnSWT HIGH FIDELITY 
DISCOUNT WAREHOUSES 

(oept. p.w.) Reservoir Rd., Clough Rd., Hull HU6 7QD ™- JJ™ 
(D.pt. p.w.) 68A Armley Rd. (Artist St.), Leeds LSI2 2EE t.l: 
(D« P t p.w.) Tees way, Portrack Lane, North Teesside 

Industrial Estate, Teesside, TS 18 2RH 

(Oept p.w.) Heeley Road, Selly Oak, Birmingham Free 

Tel. 021-472 6181 T«ChlllC»l 

(Deptp.w.>7 ( Newhaven Road, Edinburgh EH6SQX Advisory 

Tel. 544 8501 Service. If 

(D.pt. p.w.) Syston Street, Leicester t«i. 52236 |„ ,j ou bi, 

prices quoted are genuine. All items offered available at these Prices M |, „ t | 



Jltru flic yd'uiiic *-**• ■*»■•— — .*.w— — - - . 

at the time this issue closed for press. Add 75p for postage, packing and insurance jMaM orders 

(Cartridges 20p) or if Securlcor delivery required add £1-75 only. Make cheques. Money 
Orders payable to "COMET" 




WITHIN "72 HOURS 
(Add £1-75 only for Securicor delivery) 

ALL GOODS FULLY INSUREO AGAINST 
LOSS OR DAMAGE WHILST IN TRANSIT 



679 



- 



0K9t A FAST EASY 
WAY TO LEARN BASIC 
RADIO & ELECTRONICS 



* 



Build as you learn with the exciting 
new TEGHNATRON Outfit! No mathe- 
matics. No soldering— you learn the 
practical way. 



Learn basic Radio and Electronics at home— the fast, modern way. 
Give yourself essential technical "know-hoW— like reading circuits, 
assembling standard components, experimenting, building — quickly and 
T. I .u u i T l i and en . Joy everv ">oment. B.I.E.T.'s Simplified Study 
Method and the remarkable TECHNATRON Self-Build Outfit take the 
mystery out ot the subject, making learning easy and interesting. 

Even if you don't know the first thing about Radio now, 
you'll build your own Radio set within a month or so! 



. . . and what's more, you will 
understand exactly what you are 
doing. The TECHNATRON Outfit 
contains everything you need, from 
tools to transistors — even a versatile 
Multimeter which we teach you to 
use. All you need give is a little of 
your spare time and the surprisingly 
low fee, payable monthly if you 
wish. And the equipment remains 
yours, so you can use it again and 
again. 

Vou LEARN— but it's as 
fascinating as a hobby 
Among many other interesting 
experiments, the Radio set you 
build — and it's a good one — is really 
a bonus. This is first and last a 
teaching course, but the training is 
as fascinating as any hobby and it 
could be the spring-board for a 
career in Radio and Electronics. 




A 14-year-old could understand and 
benefit from this Course — but it 
teaches me real thing. The easy to 
understand, practical projects — 
from a burglar-alarm to a sophisti- 
cated Radio set — help you master 
basic Radio and Electronics — even 
if you are a "non-technical" type. 
And, if you want to make it a 
career, B.I.E.T. has a fine range of 
Courses up to City and Guilds 
standards. 



New Specialist Booklet 

If you wish to make a career in 
Electronics, send for your FREE 
copy of "OPPORTUNITIES IN 
TELECOMMUNICATIONS / TV 
AND RADIO". This brand new 
booklet— just out — tells you all 
about TECHNATRON and 
B.I.E.T.'s full range of courses. 



Opportunities in 

^^communications 
TV and Radio 




BRITISH INSTITUTE 

OF ENGINEERING 

TECHNOLOGY 

Dept. B8, ALDERMASTON COURT, READING RG7 4PF 



POST THIS COUPON FOR FREE BOOK 



I To B.I.E.T. Dcpt. B8 Aldermaston Court, Reading RG7 4PF I 
| Please send books and full information — FREE and without 
obligation. 



H 


NAME 




ADDRESS 








BIET 






AGE 



BLOCK CAPITALS PLEASE 



I BRITISH INSTITUTE OF ENGINEERING TECHNOLOGY | 

■ Accredited by ihe Council for the Accreditation of Correspondence I 



Colleges 



WICKS 



FOR 
BARGAINS 



E.A. STEREO AMPLIFIER: 

5 watts per channel; In attractive 
afrormosia veneered sleeve. Controls: 
On-off volume: Bass: Treble: 
Balance: Selector: Headphone Jack. 
Ceramic or Magnetic PU. Radio and 
Tape Inputs: Tape output and 
speaker output. Fully guaranteed 12 
months parts. 6 months free service. 
Size 14±"W x 9»"D x 45"H approx. 
£16 50 inc. post. 



3 WAY SPEAKER SYSTEM: 

8" twin cone Bass speaker and 3" 
tweeter, fitted in extremely elegant 
teak veneered cabinet. Size : 18i"H x 
1H"W x 10"D. 8 ohms handle 10 watts. 
£7 50 inc. Carr. 



GARRARD OFFERS 

Garrard SP25 Mk III (Rec. Price 

(£15-85) Our Price £11 -25. Carr. & 

Ins. 50p. 

Garrard SP25 Mk III ready wired in 

beautiful teak plinth with tinted perspex 

cover. (Fitted with 5-pin DIN plug or 

phono plugs— state choice) (Rec. 

Price £23-19). Our Price £16. Carr. & 

Ins. 75p. 

Or with choice of fitted cartridges. 

SP2S Mk III Sonotone 9TAHC (Rec. 

Price £27-29) Our Price £18. Carr. & 

Ins. 75p. 

SP25 Mk III Shure M3DM (Rec. 

Price £31-02) Our Price £20. Carr. & 

Ins. 75p. 

SP25 Mk III Goldring G800 (Rec. 

Price £36-19) Our Price £21. Carr. & 

Ins. 75p. 

SP2S Mk III Shure M55E (Rec. Price 

£36-16) Our Price £21. Carr. & Ins. 75p. 

Note I Garrard SL65B (Automatic 

Changer version of SP25 Mk III) 

alternatively supplied— please add 

£3 to above prices. 

Garrard AP76 (Rec. Price £27-85) 

Our Price £18-85. Carr. & Ins. 50p. 

Garrard AP76 ready wired in beautiful 

teak plinth with perspex cover (fitted 

with 5 pin DIN or Phono plugs). 

Please state choice. (Rec. Price £39 85). 

Our Price £24-94 Carr. & Ins. 75p. 

OR WITH CHOICE OF FITTED 

CARTRIDGES. 

Garrard AP76 Shure M3D (Rec. 

Price £47-26) Our Price £28-94. 

Carr. & Ins. 75p. Garrard AP76 Shore 

M55E (Rec. Price £52-82). Our Price 

£31 -35. Carr. & Ins. 75p. 

Garrard AP76 Goldring G800 (Rec. 

Price £52 82) Our Price £31-35. Carr. 

A Ins. 75p. 

Garrard 2025TC fitted with stereo/ 

mono cartridge. £8-99. Carr. Paid. 

TEAK PLINTH & PERSPEX COVER 

Ready cut to take 2025TC, SP25 III, SL65B 
available at £4-99. Carr. & Ins. 35p. 



CARTRIDGES (Ml with diamond stylus) 

Sonotone 9TAHC dia. Rec. Price 

£4-10. Our Price £1-99 

Shure M3DM (Rec. Price £7 41) Our 

Price £4 87. 

Shure M55E (Rec. Price £12-97) 

Our Price £9-00. 

Goldring 800 (Rec. Price £1300 

Our Price £7-50. 

Goldring 800 H (Rec. Price £10-69) 

Our Price £6-99. 

P & P 18p any type 



Guaranteed all 
brand new best 
quality goods. 
No rubbish. 

Mail order only. 

All enquiries 
SAE please. 



Special Offer) 
Grundlg GDM312 
Dynamic Micro- 
phones. List £7.35 
OUR PRICE £3. 
P & P 30p 



Hi-Fi Stereo 
Headphones 

(Value £5 00) 

Only £2-25 Inc. pott. 



Speaker Cloth 

Best quality. Width 
36'. Under half price at 
55p per yd. Black with 
gold fleck, will blend 
with any room setting. 
End of stock line, yds 
and yds must go. 



Plugs, Sockets 

and Leads. 

Phono plugs; 3p each 
30p per dozen. 

2 pin Din spkr. plugs 
10p each. 

3 pin Din plugs. 
1Sp each 

S pin Din plugs. 
13p each. 
5 pin Din sockets 
(chassis) 7p each. 
Stereo Jack Sockets 
c/cct. 13p each. 
Phono sockets 
(chassis) 2 way 3p; 3 
way 4p; 4 way Sp. 
6ft. stereo lead 5 pin 
Din to open end. 45p 
6ft. stereo lead 2 
phono to open end. 37p 
12ft. spkr. lead 2 pin 
Din to open end. 40p. 

Please add P 4 P5p. 



100 Mixed 
Resistors 

i watt 10% all best 
quality (no ex govern- 
ment) 40p. 



Pots 

100Kx100Klins4Logs. 
stereo. 3Sp inc. post. 
100K DP switch stereo, 
log. 4Sp Inc. post, 
50K single Balance. 
1Sp inc. post. 



4 B.A. brass nuts 

SO for 2Sp Inc. pott. 



Speaker cabinets 

Attractively veneered 
in afrormosia, black 
front. Size approx. 
7i"W x 9|"D x 4i"H. 
Ready cut to take 
8" x 5" speaker. 
£1 -99. P. & P. 12p. 



D. T. WICKS & CO. 49 North Station Rd, 

Colchester, Essex. Tel: (0206) 78807 



600 



ufflrJ 



RUSSIAN WORLD BEATER I 



VEF204 

ft WAVEBAND 

10 TRANSISTOR 

PLUS 2 DIODES 

PORTABLE RADIO 



AND NOW WITH 

SHIP-TO-SHORE 

MARINE BAND 



<T£13-97p 

i ,v BOX POST ETC. 50p 

MAINS/BATTERY 
ELIMINATOR toextra 




^fMJD STATE 



MM 



iVdT 

{couldn't' 

UVEN MAKE THE f> 
OR OUR FANTAST/C 



wee! 



*COMPARE IT'S PERFORMANCE 

with £42 RADIOS,' 



Important: This latest 1971 mode] incorporates all the latest technological improvements 
snd supersedes all earlier models! Tes DESIGNED FOB WOELD WIDE RECEPTION 
it'll probably make toot present radio seem like a " crystal set "! It even incorporates 
a special MARINE WAVEBAND to receive spoken communications Irom ship-to-shore! 
We're almost giving them away at only £13-97p — a mere fraction o! even today's Russian 
miracle price! Compare performance with £48 radios! 'Refund if not astounded ! Purer and 
sweeter tone than ever! Wider band spread lor "pin-point" station selection! The Russians 
have really surpassed themselves this time proving again their ability in the field of space 
communications. Yes, 8 separate wavebands, including Standard Long, Medium snd Short 
waves to cover the world, PLUS special " ship-to-shore " MARINE BAND! Thousands ol 
different transmissions and stations at your fingertips 24 hours a day, including ships at pea. 
etc.. and messages from all over world — truly nothing is secret! Ton must hear It to believe 
it! Superb, sweet tone — controlled irom a whisper to a roar I Push-pull output! Separate 
ON/OFF volume- k Treble/Bass tone controls! Press-button dial illumination! Take it 
anywhere — runs economically on standard batteries or through btv.tery eliminator from 
220/240v. AC mains. Internal ferrite rod plus telescopic aerial- It's also a fabulous CAB 
RADIO! Black A Chrome case llins x Bins, z 8{ina. overall appro*. Made to give years ol 
perfect service. Complete with WRITTEN GUARANTEE, manual with simple operating 
Instructions & circuit diagram. ONLY £13-87p (with mains/battery eliminator £l-88p 
extra). POST SOp. Standard batteries 88p extra. Can also be used through extension amplifier, 
tape recorder or public address system. Send today or call. (SORRY — we cannot change 
these new radios for any earlier model already purchased ! ) 



"Tab2 ou :i^IZZ2H5£ 
•\gniii"RSTCL^^ 

"BRAND NEVV 



PLAYER 



with 

remote control microphone 




MAKE NO MI8TAKE— this is the EXPENSI VE m odel with "PIANO KETBOABD" CON- 
TBOL PANEL and SPECIAL RECORDING LEVEL! SAVE £13 98! Due to price we cannot 
mention famouH maker's name — but rest assured you're getting one of the BEST! 1971 
cassette model — no fiddling with awkward tape and reels, Just "slap in" a cassette and off 
you go! (takes SO-. 60-, and 90-mlnute standard Philips Cassette tapes obtainable every. 
Where). Amazing performance ensures perfect taplngs and superb reproduction Remote 
control microphone. Separate volume control! Rapid rewind! Beautiful tone from a 
whisper to a roar 1 Completely self-contained — record anywhere. Separate Jacks for remote 
control microphone, etc. Sixe 9" x 4t* x 2|" overall approx. Case design can vary slightly. 
With carry handle. With WRITTEN G'TEE and instructions. Only £12 99. post 80*. ALSO 
AVAILABLE: SPECIAL BATTERY, MAINS AC/DC MODEL, ready to plug in. £8 50 extra 
If required. Refund g'tee. BONDS one per customer: Cassette tape, set of Standard batteries 
and microphone stand all lor 51p extra il required. Send quickly or call. 
Send quickly to Dxbridge Road or call at either store. (COMMERCIAL TRAVELLERS 
NOTE: Merchandising Office at Holborn.) 



SHOPERTUNITIES LTD. E3E 



Dept. WP/F/12. 1S4 UEBBXDGE ED. (facing Shepherds Bush Green). LONDON, W.12 
8AQ. (Thurs. 1, Fri. 7). Also 87/89 HIGH HOLBORN (opposite Chanc;ry Lane), LONDON. 
W.C.I. (Thursday 7 p.m.). BOTH STORES OPEN MON-8AT FROM 9 a.m.-e p.m. 



BATTERY MAINS AC DC 



Combined 



CASSETTE 

TAPE RECORDER 

& PLAYER 




.*ggfr 



I WITH REMOTE 

I CONTROL MICROPHONE 

FANTASTIC (even by our standards!) Brand new — the latest sensation in the world oj 
sound! First class makers! Not only a fabulous VHP AM/PM Radio AND Cassette Tape 
Recorder and Player combined, but it also runs off standard batteries or mains (simply 
plug in the built-in 220/240v. AC line cord) NoW you can record and play back anything! 
anywhere! Ton can even tape direct Irom the Radio as you listen! RECOMMENDED RETAIL 
PRICE GENUINELY £44. YET WE OFFER AT ALMOST HALF PRICE! Just look at these 
wonderful features: — 'Press button Keyboard Control panel! 'Hew 'pop-up' Cassette 
ejection system! "'MAGIC EYE" Visual Battery check. 'recording level indicator! "Separate 
ON/OFF, and HI-LO volume controls! 'Heavy duty built-in speaker! 'Earphone (for personal 
listening or "monitoring") and extension speaker sockets! "Remote control microphone! 
•Built-in swivel telescopic extension aerial (24 inches approx)! Magnificently made cue, 
size lljins. x 8iins. x 8fins. overall approx., with "pull-out" carry handle. DESIGNS VARY 
SLIGHTLY. Takes standard 30, 80. 90 or 120 minute Philips Cassette Tapes obtainable 
everywhere. But wait, the amaiing built-in full circuit VHP AM/PM Radio gives you superb 
clarity of tone and Incredible station selection — Unique rotating Station Selector Dial — 
tret all local city & regional stations in every part of the country plus B.B.C. National 
VHP. Picks up dozens of foreign stations and short mobile transmissions. Fabulous in 
car! You could pay ££££'s more for a Car Radio or Car Cassette Tape Player ALONE I 
OUR PRICE. ONLY £23 75 CABB. ETC. 35p. Complete with simple instructions, personal 
listening earphone, remote control microphone with on/off switch and microphone stand, 
with written guarantee. BONDS OFFER— Standard Batteries and Cassette Tape 25p extra. 
Refund g'tee. It's an offer you cannot afford to miss! 



»*w 



^ecouwNJ~^^ 

^FORTHISPRfCEf 



m 



WORLDWIDE 

RECEPTION 

THOUSANDS OF TRANSMISSIONS. 
^ AM) STATIONS THE W0B10 0VEB! 

i ■ ■ ■ m m mm 



PORTABLE RADIO 

£9-97 



-V 



f«U. 



BOX POST ETC. 43f I 



N0TJUSTARADI0-BUTTECHNDL0G1CAL MAGIC! 



^COMPARE 

ITS PQtfORMANC£ with 

£34 RADIOS' 



THE LATEST 1971 MODEL. SUPERSEDING ALL PREVIOUS 
MODELS:— FANTASTIC BRAND NEW RUSSIAN "MERID- 
IAN" 8-WAVEBAND PORTABLE BADIO. DESIGNED FOB 
WORLD WIDE RECEPTION. Only put into production after 
incorporation ol every conceivable possible up-to-date tech- 
nological improvement had been carefully considered and thoroughly examined. So advanced 
it will probably make you present radio seem like a "crystal set"! It's lar better than any 
6-wave radio even they have produced! Finest value we've ever offered! We're almost 
giving them away at £9-97—a mere fraction ol even today's Russian miracle price! We 
challenge you to compare the performance and value with t hat of £34 radios I 
ir Instant refund if you are not astounded I Purer and sweeter tone than ever! Much wider 
band spread than hitherto lor "pin-point" station selection. Once again the Russians have 
proved their fantastic ability in electronics — brilliantly reflecting their advanced micro- 
clrcultry techniques In the field of spaceship and satellite communications. Yea, 6 separate 
wavebands. Including Standard Long, Medium and Short Waves to cover world! Unique 
aide control waveband selection unit gives incredible ease ol station tuning! Thousands ol 
different transmissions and stations at your fingertips 24 hours a day, even ships at sea and 
messages from all over world — nothing is secret! The radio enthusiast has she world in his 
hand! Superb, sweet tone — controlled from a whisper to a roar. Push-pull output ! Separate 
ON/OFF volume Treble/Bass tone controls! Take it anywhere — runs economically on 
standard batteries. Internal ferrite rod aerial plus built-in telescopic aerial extending to 
full S3 ! in. length. It's also a fabulous CAB BADIO — any speed, requires no additional aerial. 
UNIQUE! Elegant Black. White and Chrome finish case. 8IZE 101' x 8' x 3J" overall 
approx. Magnificently designed, made to give years ol perfect service. With WRITTEN 
GUARANTEE, manual with simple operating instructions and circuit diagram. ONLY 
£9 97. POST ETC. 43p. Standard batteries 25p extra it required. Can also be used through 
extension amplifier, tape recorder or public address. 



A VISIT TO SHOPERTUrtTTTES COULD SAVE YOU Ut't'. 



681 




CN. 240/2 Miniature soldering iron 15 watt 240 volts, fitted 
with nickel plated 3/32" bit and packed in transparent 
display box. Also available for 220 volts. Price £1.70 

CN.240 Miniature soldering iron 15 watt 240 volts, fitted 
with iron coated 3/32" bit. Up to 18 interchangeable spare 
bits obtainable. This iron can also be supplied for 220, 
110, 50 or 24 volts. Price £1.70 

G.240 Miniature soldering iron 18 watt 240 volts 
extensively used by H.M. Forces. Suitable for high speed 
soldering and fitted with iron coated 3/32" bit. Also 
available for 220 volts. Spare bits 1/8", 3/16" and V»" are 
obtainable. Price £1.83. 



"""tor., printed carcuis. «c. 




CCN.240 New model 15 watt 240 volts miniature soldering 
iron with ceramic shaft to ensure perfect insulation 
(4,000 v A.C.). Will solder live transistors in perfect 
safety, fitted with 3/32" iron coated bit. Spare bits 1/8" 
3/16" and '/•" available. Can also be supplied for 220 volts. 
Price £1.80 

CCN.240/7 The same soldering iron fitted with our new 
7-star high efficiency bit for very high speed soldering 
The triple- coated bits are iron , nickel and chromium plated. 
Price £1.95 




E.240 20 watt 240 volts soldering iron fitted with 
V*' iron coated bit. Spare bits 3/32", 1/8" and 3/16" 
available. Can also be supplied for 220 and 110 volts. 
Price £1.80. 

ES.240 25 watt 240 volts soldering iron fitted with 1/8' 
iron coated bit and packed in a transparent display box. 
Spare bits 3/32", 3/16" and W available. Can also be 
supplied for 220 and 110 volts. Price £1.83 




Price £2.75 



SK.1 
SOLDERING KIT 

The kit contains a 1 5 watt 240 volts 
soldering iron fitted with a 3/16" bit, 
nickel plated spare bits of 5/32" and 
3/32", a reel of solder, heat sink, 
cleaning pad, stand and booklet "How 
to Solder". Also available for 220 volts. 




^U 



Price £2.40. 



SK.2 
SOLDERING KIT 

This kit contains a 
15 watt 240 volts 
soldering iron fitted 
with a 3/1 6" bit. nickel 
plated spare bits of 
5/32" and 3/32", a reel 
of solder. Heat Sink, 
1 amp fuse and booklet 
"How to Solder". 




MES. 12 

A battery operated 
12 volts 25 watt 
soldering iron complete 
with 15' lead, two 
crocodile clips for 
connection to car 
battery and a booklet 
"How to Solder" packed 
in a strong plastic wallet. 

Price £1.95. 



cut out this coupon 

and answer your soldering 
problems^* 



m 




I 



from electrical, radio or car accessory 
shops or from Antex Ltd., Freepost 
no stamp required) Plymouth 
PL1 1BR Telephone 0752 67377/8 



] Please send the Antex 
colour catalogue. 

Please send the following: 




I enclose cheque/P.O./Cash ' 
(Giro No. 2581000) 



Name _ 
Address 




I 



682 




PRACTICAL 

WIRELESS 



VOL 47 NO 8 

Issue 778 



DECEMBER 1971 



But Why? 



ONE of the most difficult tasks to face a technical journalist 
is to write an article for the absolute beginner. It is 
comparatively easy to prepare something for the advanced 
reader, for the author is aiming at those generally a little 
below his own standard. An article beamed at middle-of- 
the-road readers is, perhaps, the least troublesome be- 
cause the author does not have to dwell on fundamentals 
or to go too deeply into advanced theory. 

But the snags come when a writer has to do something 
for "the beginner" — a term full of pitfalls, for there are 
various degrees of that species. The main difficulty for 
the writer is to put himself in the position of his potential 
readership and to anticipate questions which might arise 
in the mind of a newcomer to the subject. A point which is 
to the author perfectly obvious may cause a beginner to 
feel perplexed and form questions in his mind. Taken to its 
extreme, the author must, as far as possible, assume that 
the newcomer knows virtually nothing — an impossibility in 
practical terms, for some sort of mental line has to be 
drawn. 

In P.W., we have to cater for all grades of experience. In 
general, a constructional article is geared to provide 
sufficient information for a constructor who has reached 
a stage at which he should reasonably be expected to be 
able to tackle the particular project. Since levels vary so 
widely, some readers complain that articles are too elemen- 
tary while others think they are too advanced. This is the 
perpetual dilemma of trying to please everyone! 

We do feel, however, that it is not a bad thing to err on 
the side of simplicity, for if the beginner is the one who 
wants to ask the most questions it is obvious that he is the 
one who needs greater attention. This is one reason why 
we have periodic bursts of special features for the beginner, 
such as the new series on transistor circuitry started in 
October and the extra 8-page supplement included with 
this issue aimed at providing some basic guidance on the 
main components likely to be encountered by the home 
constructor. 

Author Hellyer said in the October issue, "... any be- 
ginner worth his salt is going to say 'But Why???' We 
would go further, for the path of progress of any enthusiast 
will be travelled faster if he makes a point of always asking 
'But Why?' — and finding the answer — when confronted with 
an aspect not fully understood. 

W. N. STEVENS— Ed/for. 



NEWS AND COMMENT 




Leader 


683 


News . . . News . . . News . . . 


684 


MW Column by Charles Molloy 

On the Short Waves 
by Malcolm Conn ah and 
David Gibson, G3JDG 


723 
724 


Letters 


729 


CONSTRUCTIONAL 





9-Band Short Wave Radio 

by R. F. Graham 686 

4-20V Regulated Power Unit 

by A. Burnett 693 

Transistor Tape Recorder 

by W. Langley 698 

Comprehensive Multi-Band 

Receiver, Part 2 

by F. G. Rayer, G30GR 705 

Modular Audio Mixing System, 

Part 3 by F. C. Judd 715 

2-Octave Miniature Organ, 

Part 2 by F. C. Judd 718 

Digital Frequency Counter/Timer, 

Part 4 by John Thornton 

Lawrence, GW3JGA 720 

OTHER FEATURES 

Transistor Circuitry for Beginners, 
Part3byH.W. Hellyer 710 

SERVICING, Part 7 by G. J. King 730 

SPECIAL FEATURE 

SUPPLEMENT: 
Components Dictionary by S. Yeatman 

JANUARY ISSUE WILL BE 
PUBLISHED ON DECEMBER 3rd 






®IPC Magazines Limited 1971. Copyright In all drawings, photographs and articles published in "Practical Wireless" is fully protected, and reproduction or imitations in 
whole or in part are expressly forbidden. All reasonable precautions are taken by "Practical Wireless" to ensure that the advice and data given to readers are reliable. 
We cannot, however, guarantee it, and we cannot accept legal responsibility for It. Prices are those current as we go to press. All correspondence Intended for the Editor 
should be addressed to Fleetway House. Farringdon Street, London, EC4A 4AD. Queries must be accompanied by a stamped, addressed envelope. Address correspon- 
dence regarding advertisements to Advertisement Manager, Fleetway House, Farringdon Street, London, EC4A 4AD. 



683 






news... News... News 



»## 



BSR Transcription 




ilSR's new unit, the McDonald 
810, priced at £45-51 for the basic 
unit, was shown at the Audio Fair 
for the first time. Features in- 
clude push button operation, a 
pitch control for absolute accuracy 
of turntable speed and a virtual 
friction free pick up arm move- 
ment which is gyroscopically con- 
trolled with a concentric gimbal 
mount. 

Twelve months ago, BSR 
Limited launched the BSR 
McDonald consumer range. The 
810 is the culmination of design 
expertise and production effi- 
ciency which has successfully pro- 
duced in succession the wide sell- 
ing MP 60 and HT 70 units. 

The technical data for the 810 
is impressive. It is a two speed 
player, SS» S and 45 rpm, utilising 
as its heart a 4 pole dynamically 
balanced synchronous motor driv- 
ing a 7 J 4lb. diecast balanced turn- 
table. A stroboscopic centre plate 
when coupled with the pitch con- 
trol ensures absolute turntable 
accuracy. A low mass pick up 
arm, over S^in. in length has less 
than • 5° per inch tracking error. 

Although primarily a single 
play unit, versatility comes with 
an interchangeable umbrella 
spindle giving true automatic 
function if required. 



Sonex 72" 

The Third International Exhibi- 
tion of Audio Equipment, 
operated by British Audio Promo- 
tions Ltd, on behalf of the mem- 
bers of The Federation of British 
Audio will be mounted at the 
Skyway Hotel, Bath Road, Hayes, 
Middx (near London Airport) over 
the period from Wednesday, 
March 22, 1972, to Sunday, March 
26, 1972. 

684 



Hacker RP73 

This newly-designed successor to 
the famous Hacker Autocrat RP33 
home/car portable radio incor- 
porates an integrated circuit and 
ceramic filter in its design. 

In common with its predecessor 
the Autocrat Mark 2 Model RP73 
offers extreme portability for use 
in the home, and a special change- 
over aerial circuit for inter- 
ference-free reception in a car. 
Price is £25-25 including Pur- 
chase Tax. Hacker Radio Ltd, 
ftorreys Drive, Cox Green, 
Maidenhead, Berks. 




Meteronic Scope 




The MSB 101 oscilloscope has a 
bandwidth of d.c.-8MHz; vertical 
sensitivity of 100mV/cm-50 V/cm ; 
sweep speed range of lOOnSec/cm- 
150mSec/cm; and a unique signal 
locking circuit which by means of 
a single control enables the user 
to select through 'Free Run', 'In- 
ternal Signal Sync' to 'Trig- 
gered.' Also provided is switch 
slope selection. Fibreglass P.C. 
boards are fitted as standard. The 
MSB 101 size is 8 x 6 x 4in. and 
weighs 51b. Price : £69. Meteronic, 
114/116 Shipbourne Road, Ton- 
bridge, Kent. Tel. Tonbridge 
61448. 



Dayslrom Throw It Around 

Daystrom has introduced a 660 
series drop-proofed multimeter. 
These precision meters are war- 
ranted to operate within specifica- 
tion after being dropped from a 
height of five feet. The meter 
mechanism floats inside a sealed, 
high-impact plastic case. These 
multimeters also have tempera- 
ture compensation, with shielded 
and electrically protected meter 
movement. The meter maintains 
accuracy in extreme environments 
and will not be damaged if, as 
sometimes happens, the user 
accidentally connects it to a high 
voltage source. Daystrom sales- 
men sometimes demonstrate the 
660 series by throwing the meter 
on the customer's floor. So far, 
customers have had a worse shock 
than the meter! So, if you feel 
like chucking a £29-85 meter 
about, contact Daystrom (Senium- 
berger), Bristol Road, Gloucester 
GL2 6EE. 




news.., news... news... 



Litesold System 

The Litesold ETC/1 Soldering 
System consists of a lightweight 
soldering iron which is fed from a 
solid state power/control unit 
giving fully automatic electronic 
control of the temperature of the 
front of the bit. 

Operating temperature is fully 
adjustable by means of a calibra- 
ted dial on the power unit over 
a wide range from 150/400°C. 
Thus there is no need to change 
bits for different settings which 
can be altered and read-off 
instantly. 

The most important feature is 
the total avoidance of electrical 
disturbance and R.F.I, generation 



A New Iron From Anlex 




The element of this new Antex 
soldering iron is totally enclosed 
within a ceramic shaft. (Alu- 
minium oxide.) 

Near perfect insulation has 
been achieved; as a result there 
is no measurable leakage and 
live transistors can be soldered 
without risk of damage. 

The 15 watt element generates 
a temperature of up to 450°C. at 
the tip to facilitate high speed sol- 



dering. A choice of four iron 
coated bits and one special bit 
plated with iron, nickel and 
chrome is available: all designed 
to ensure long bit-life. 

The complete iron has passed a 
test of 4,000 volts a.c. and each 
production model is tested at 
2,000 volts a.c. Further details 
from: Antex Limited, Mayflower 
House, Plymouth, Devon. 




by the control unit which allows 
the iron to be used on ultra-sensi- 
tive equipment and components. 

The plug-in soldering iron con- 
tains no control components ex- 
cept the temperature sensor and 
is as cheap and simple to repair as 
an ordinary iron. 

Long-life bits slip over the heat- 
ing element and are available in 
a range of tip sizes. Price is 
£19-80. Light Soldering Develop- 
ments Ltd., 28 Sydenham Road, 
Croydon, CR9 2LL. 



Eagle International 

Eagle International will add a 
quadraphonic synthesiser to its 
range in January 1972. Desig- 
nated AA10, it enables a conven- 
tional stereo system to be turned 
into a quadraphonic system by 
dividing the 2-channel output 
from a stereo amplifier into 3 or 
4 channels based on sum and 
difference signals. 



Ever Ready Go's Rechargeable Cells 

These cells, marketed by the Ever 
Ready Co. are sealed Nickel Cad- 
mium types and have been used 
for some time now as the re- 
chargeable power units in small 
portable appliances where the 
charging unit is integral. Now 
they are available to the home 
constructor and prices vary with 
quantity and capacity but typic- 
ally a U2 size replacement would 
cost something over £2 for a 
single cell but would be propor- 
tionately reduced for larger quan- 
tities. 

Eutton cells are more normally 
supplied as higher voltage pre- 
packed batteries and typically a 
4-8V 550m Ah battery as used in 
radio controlled models, would 
cost around £3-30. 

Cells and battery packs are 
available direct from the manu- 
facturer and the smaller button 
cell packs from reputable sup- 
pliers to the radio controlled 
model field. The Ever Ready Com- 
pany (Gt. Britain) Ltd., Special 
Battery Division, Hockley, Essex. 





TYPICAL CYLINDRICAL CELL CONSTRUCTION 



TYPICAL BUTTON CELL CONSTRUCTION 



685 




R.F.GRAHAM 



ANY means of spreading the great number or 
short wave transmissions which can be heard 
over an increased tuning range is helpful, 
simplifying and easing tuning. When several ranges 
are needed it becomes difficult to use separate 
inductors for each range, involving a large number 
of coils, with all the associated switching. 



C1.C4.C12=150p C2.C10=50p C3.C11=1©Qp C5.G13 = 200p C6.C1* = 250p C7.C15--: 



In the receiver described here, only two coils 
are required band-changing being achieved by 
bringing in pairs of fixed capacitors. This breaks 
up the full tuning range into a number of smaller 
divisions. 



CIRCUIT 

Fig. 1 is the mixer stage circuit the wiring being 
very much simplified by using this switching arrange- 
ment. LI is the aerial coil, tuned by VC1, and L2 
the oscillator coil, tuned by VC2. VC1 and VC2 are 
sections of a small ganged capacitor, operated 
through a cord drive. 

The 2-pole 9-way rotary switch S2/S3 selects the 
required band. With the switch in position 1, VC1/2 
alone are in use, for the highest frequency band. 
When the switch is in position 2, C2 and CIO are 
in circuit. Each of these capacitors is 50pF, so the 
next range runs on from the frequency reached 
when S2/3 was in position 1, and VC1/2 fully closed. 
In a similar manner, position 3 of the switch brings 
in C3 and Cll, each of lOOpF. The next lower fre- 
quency band employs C4 and C12, each of 150pF, 
with the switch in position 4. This continues for the 
nine ranges, each pair of capacitors being 50pF 
larger in value than the previous pair. 

VC1/2 has a swing of a little over 50pF, so that 
ranges overlap. VC3 is a panel trimmer, which can 
be set for best volume on any band, or when alter- 
ing the aerial. 51 is an aerial switch, used for the 
attached telescopic aerial or an external aerial. 

The capacitors C2 to C9 for the aerial circuit, and 
CIO to C17 for the oscillator, are 1% or 2% silver- 
mica, and any variation in the exact capacitances 
of the components used is easily cancelled out by 
VC3. 



IF AMPLIFIER 

A conventional high gain intermediate frequency 
amplifier is used, Fig. 2. This has two double-tuned 
i.f.t.'s, and one single tuned i.f.t. resulting in good 
selectivity. 

The i.f. amplifier is wired as a separate unit, on 



686 




The complete circuit of the 9 Band 
Receiver Is made up of Fig. 1, (left) 
mixer stage ; Fig. 2, i.f. stages and 
Fig. 3 the audio output stage. The 
constructor only need assemble the 
mixer and i.f. stages since the audio 
stage is a packaged module. 



a small insulated board. Input from the mixer stage 
is to pin 2 of i.f.t.l and audio output is from Dl and 
C26. VR1 is the usual audio volume control. 



AUDIO AMPLIFIER 

This provides high gain and 330mW output into 
a 15 ohm speaker. Fig. 3 is the circuit and Tr4 is 
the first a.f. amplifier stage, stabilised by R14. Out- 
put from Tr4 collector is via C30 to the base of 
Tr5, which with Tr6 forms a Darlington pair driver 
for the output transistors Tr7 and Tr8. These form 
a push-pull complementary-symmetry stage, work- 
ing in Class B, with diode D2 for thermal stabilisa- 
tion. Feedback through R17 maintains operating 



conditions for the four directly-coupled transistors 
Tr5 to Tr8. 

This circuit has plenty of amplification and volume. 
In order to simplify construction of the whole 
receiver, the audio amplifier is obtained as a printed 
circuit package, ready for use, and incorporating 
matched transistors. 

A is the common positive line, and D the nega- 
tive line. Point C is for audio input. The resistor R13 
is included in the amplifier. R12, which is in series 
with R13, was found to be necessary for stable work- 
ing in this particular receiver. 

Leads from D (battery negative fine) and E run 
to the 15 ohm speaker. The circuit is of the trans- 
formerless type and a speaker of other than 15 ohm 
impedance should not be used. 



Mixer— 




Fig. 2. The circuit of the i.f. stages, 
constructed as a separate unit on a 
paxolin panel (See Fig. 6). The in- 
put comes from pin 8 on L2 in the 
mixer stage. 



Fig. 3. Since the audio stages are 
contained within a packaged mod- 
ule this circuit of the 5 transistor 
unit is given for interest only. 
Input from the i.f. assembly goes 
to pin C, the loudspeaker to pins 
D and E and the earth line to the 
onloff switch S3. (Note: C23 
should read C32.) 




687 



MIXER STAGE ASSEMBLY 

A lOin. x 4in. flanged plate (universal chassis 
member) serves as panel for the controls and the 
top of the case. The controls are placed lin. from 
the bottom of this plate, VC3 and the cord drive 
spindle being l 3 4 in. from the plate ends and S2/3 
and VR1- equally spaced . between these. 

VC1/2 is fixed as in Fig. 4 so that the top of the 
drum is about 1 ain. below the top of the plate. One 
pulley is above the cord drive spindle, to keep the 
cord parallel with the plate. The second pulley 
guides the cord clear of the bushes of S2/3 and VR1. 
The pulleys are on bolts fixed with lock nuts to the 
plate. The cord is given one complete turn round 
the drive spindle, then passes round the wheels and 



* components list 




Cores 



Fig. 4. Layout of the mixer assembly built on an aluminium plate. 

drum. It is taken through the drum slot, and tied 
so that it is under tension from the spring. 

Fig. 4 shows wiring, etc., for this stage. LI, L2 
and the other items are mounted on a piece of 
paxolin 5in. x 2 1 2 in., which has a cut-out section to 
clear S2/3. VC1/2 is bolted to the lOin. x 4in. plate, 
and the paxolin is in turn bolted to the underside 
of the ganged capacitor. Additional support is given 
by a bracket attached to the paxolin and rear of 
the 9-way switch. 

Transistor Trl has three leads soldered directly 




Resistors: 

R1 10ki'l 
R2 2-7kQ 
R3 1MJ 
R4 1kO 



:: R5 BSkO: R9 4-7ki1 

R6 68012 R10 IkL; 

R7 8-2kfi R11 1kQ 
R8 22WI R12 4-7ki • 

AH iW 10%. 
VR1 5k;'2 potentiometer, log, with switch (S3). 



Capacitors: 

CI 150|)F 
C2 50|>F 
C3 100pF 
C4 150|>F 
C5 200i> F 
C6 250pF 
C7 300pF 
C8 350pF 
C9 400 dF 
Capacitors 
mica. 
VC1/2 
VC3 
TC1 



C10 50pF C19 01//F 

C1 1 100pF C20 001// F 

C12 150pF C21 1Q«F 6V 

C13 200pF C22 04/-F 

CI 4 250pF C23 0-04//F 

C15 SOOoF C24 0-G4hF 

C16 350pF C25 0»5»F 

C17 4G0pF C26 OOlwF 

C18 01,«F 

to C17 inc. are 1 % or 2% silver 



2 gang, 75 - 75 pF approx. See text. 
50pF air-spaced variable. 
30pF pre-set. 



Semiconduclors: 
M OC170 
Tr2 AF117 



Tr3 AF117 
Df OA81 



Inductors: 

IFT1 IFT18/465 (Denco) 
1FT2 IFT18/465 (Denco) 
IFT3 IFT14/465 (Denco) 



L1 Range 4 Blue 
(Transistor) 

L2 Range 4 Red 
(Transistor) 



Audio Amplifier : 

PC3 P< ckaged circuit (Newmarket). 

Miscellaneous : 

Cabinet: 2 off, 10in. x 4in. Universal chassis 
flanged member (Home Radio). 2 off, 7£ln x 
4|in. plywood. 2 off, 10in x Tin. hardboard. 
Tuning drive: Drum, 2|in. dia., DL34 drive 
spindle, spring, cord, pulleys (Home Radio). 
Speaker, 7in. x 3£in., !5t2. Telescopic aerial. 
Aerial socket, knobs, rubber feet. 



Fig. 5. Details of the wiring of the bandswitch S2-S3. 



to the pins of L2. The base lead B is extended by 
soldering on connecting wire, to run to C18. Con- 
nections in this stage should be reasonably short 
and direct. R3, C19 and C20 are wired to a tag under 
the paxolin, in contact with the metal frame of 
VC1/2. 

VC3 is mounted directly under VC1/2 and is con- 
nected in parallel with it by short leads. 

The bandswitch occupies the position shown in 
Fig. 4, and is wired as in Fig. 5. The switch has 
separate single-pole 9-way wafers connected directly 
to VC1 and VC2 by short leads. No extra connec- 
tion is made tc position 1. Position 2 has the pair 
of capacitors C2 and C10 (50pF each). Position 3 
has equal capacitors C3 and Cll (lOOpF each), and 
so on. 

The capacitors are best arranged to lie partly 
over the wafers, in the manner giving shortest leads 
to a stout wire which returns to the frame tag of 
the ganged capacitor. 

GANGED CAPACITOR BAND 
SWITCH 

S2/3 introduces fixed capacitor increments of 
50pF at each position. There is a certain amount 
of stray circuit capacitance, to which is added the 



688 



minimum capacitance of VC1/2. This means that 
a ganged capacitor having a maximum capacitance 
of 50pF each section is not quite sufficient and 
results in small gaps in the tuning range. 

A ganged capacitor with a capacitance swing of 
just over 50pF (say from lOpF to 70pF) would be 
ideal. To obtain a little overlap, and allow for varia- 
tions of C2 to C17, the nearest standard value is 
75pF, which is satisfactory. 

When this tuning arrangement was first used, a 
2 x lOOpF capacitor was fitted and some plates 
pulled off, but this resulted in too many being 
removed. A new capacitor thus had to be fitted. 
Caution is therefore required, if a capacitor is modi- 
fied in this way. With a 2-gang lOOpF capacitor, 
the effective value can be reduced to about 75pF 
by placing a 300pF fixed capacitor (silver mica) in 
series with each section. The lead from LI to VC1 
must then run over VC1 so that it can join the lead 
from S2. 

IF AMPLIFIER ASSEMBLY 

This is assembled and wired on a paxolin panel 
3 3 4in. x l 3 4 in. All components are mounted on one 
side and wiring is on the reverse, as in Fig. 6. Note 
that the different spacing of the pins of the i.f.t.'s 
enable these to be identified. Remember to drill 
holes for adjustment of the cores. 

Small holes are drilled for the leads of the other 
components. Note the polarity of C21 and diode Dl. 
Connections underneath are made by bending over 
the wires and snipping off the ends and by using 
thin connecting wire where required. Insulated sleev- 
ing is put on all leads where necessary. Two bolts 
holding the tags MC, locked on, will mount the 
finished amplifier and provide a positive return cir- 
cuit. 



Speaker 





Fig. 7. The i.f. and audio stages are mounted on a common panel. 

Solder a lead to pin 2 of i.f.t.l. This is later sol- 
dered to pin 8 of the oscillator coil L2. 

Take a black lead from Rll, to use as negative. 
Solder a wire to the junction of Rll and C25, as 
shown, which will later run to R4. The remaining 
external connection is from R7, C26 and Dl, and 
goes to the volume control VR1. 

Both i.f. and a.f. amplifiers are mounted on a 
piece of paxolin 5 2 2in. x 2 1 2in. which is supported 
by the bracket mentioned earlier, and by a further 
bracket bolted to the lOin. x 4in. aluminium plate. 
Extra nuts are put on the bolts holding the tags MC, 
Fig. 6. The bolts pass through the 5 J 2in. x 2 2 2in. 
paxolin. Further tags are then put on fixed with 
nuts. The tags are wired to the volume control and 
metal plate (positive line). 

The audio amplifier package 
is mounted in a similar way, Fig. 
7. R12 is soldered to point C. A 
black lead for battery negative 
is taken to point D, and white 
leads for speaker connections to 
points D and E. A red lead from 
point A runs to the positive line 
at VR1 and the on-off switch. 



ALIGNMENT 

The complete assembly on the 
lOin. x 4in. flanged plate is 
aligned and tested before fitting 
it in the cabinet. A speaker of 
the correct type (15 ohms) must 
be connected. 

The five cores of the i.f.t.'s are 
rotated with a suitable tool, such 
as the Denco TT5, for best re- 
sults. A weak signal is most 
suitable from a signal generator, 
or from a transmission, a short 
wire aerial being temporarily 



Fig. 6. Layout and wiring diagram of the i.f. 
assembly built on a paxolin panel, 3}in x 
1iin. 

689 



connected to tag 8 of LI. VR1 should be near maxi- 
mum volume, but a strong signal should be avoided 
because the automatic gain control circuit will then 
make critical adjustment of the cores difficult. 

Once the i.f.t. cores have been correctly peaked 
for best sensitivity, they should be left alone. A 
meter placed in one battery lead should show a 
current of under 15mA with weak signals, rising to 
peaks of 50mA or more with signals giving good 
volume. 

The cores of LI and L2 are then rotated until 
about 3 8 in. of threaded brass projects. Set VC3 and 
TCI at about half capacitance. Open VC1/2, set the 
bandswitch at Position 1, and rotate TCI as necessary 
to tune to about 15MHz. 

Leave VC3 and TCI, switch to Position 9, and 
close VC1/2. Rotate the core of L2 as necessary to 
tune to approximately 3-6MHz. Switch to Position 8, 
tune in a transmission, and rotate the core of LI for 
best results. 

It should then be found that with the bandswitch 
in any position, and a transmission . tuned in, VC3 
can be peaked for best reception. Should VC3 need 
to be either fully open or fully closed with the switch 
in Positions 1 or 2, re-adjust TCI as required. If VC3 
is either fully open or fully closed to give best 
results with the switch in positions near the low 
frequency end of the coverage provided (especially 
Position 8 or 9) then the core of LI needs slight re- 
adjustment to avoid this. 

It should be found that VC3 generally only needs 
one adjustment for each band and that often even 
this will not be necessary. VC3 can be peaked up 
for best reception of weak signals at any time, when 
changing the aerial, or switching SI. 

If it is found that almost uninterrupted whistles 
arise at the extreme h.f. end of the coverage pro- 
vided, include a resistor at X in Fig. 1, between 
collector and pin 9 of L2. Its value should be the 
lowest which prevents oscillation and will generally 
be around 47 ohms to 470 ohms or so. This depends 
on the individual transistor and other factors. 



CABINET ASSEMBLY 

Fig. 8 will help to clarify assembly of the case. 
Cut two pieces of hardboard lOin. x 7in. and with 
a pad saw or keyhole saw cut a hole to match the 




speaker cone. Clean up all edges with glasspaper 
and wipe off any dust. Fabric is then stretched over 
the hardboard, brought round the edges, and glued 
on the inside. 

The sides are 3-ply, each 7 1 2 in x 4 1 2 in., sanded 
and varnished. The lOin x 4 in. flanged plate form- 
ing the case bottom is placed on a flat surface, and 
the sides are positioned as in Fig. 8. Mark through 
the flange holes, drill the sides to match, and fix 
them with bolts. 

Drill the hardboard front for speaker and front 
flange, and bolt this as in Fig. 8, with the speaker 
in position. 

The receiver panel should then be finished. Cut a 
piece of plywood or other thin wood about 5in. x 2in. 
and fix this with small screws through the lOin x 4in. 
plate, to bring the tuning scale about level with the 
drive cord. Clip a small piece of tinplate on the cord, 
and solder a straight wire pointer on this, so that it 
moves along the scale. 

A piece of perspex is cut lOin. x 4in., and drilled 
to match the four control spindles and for 6BA 
bolts in line with the four holes which are in the 
universal chassis flanged plate. A piece of coloured 
card is also cut this size, and a window about 
S^in. x l^in. is cut in it with a sharp blade, to lie 
over the tuning scale. 



Position of receiver 
panel 




A view inside the 'works' shows the three units forming the complete 
receiver. 

690 



10x4" Flanged plate 



7j x 4 
Fig. 8. Details of the construction of the receiver cabinet. 

Four lin. long 6BA bolts are put through the 
holes in the perspex and card. A washer and nut 
is put on each bolt, and the nuts are tightened. An 
extra nut is the a put on each bolt, and the whole 
is fixed in place with further nuts behind the flanged 
plate. The nuts are adjusted to give about ! 2 in. clear- 
ance, to take the drum, cord and pointer. 

The assembly is then put in the top of the case, 
so that the flanged plate is about 2 2 in. down, as in 
Fig. 8, and the perspex is flush with the case front. 
Drilling positions are then marked through the holes 
punched in the flanges. The sides are drilled, and 
the receiver bolted in place. The receiver case front 
is also bolted to the front flange of the lOin. x 4in. 
plate. 

— continued on page 738 




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Goldring G800 cartridge 
(List £28-35) 

Garrard AP76 
less cartridge 



£2450 

£2900 

£11-90 
£18-40 
£19-50 



Garrard 3500 with OO •*»■"# 

Sonotone 9TAHCD stereo iJJ'JJ f 
cartridge (List £15-50) 



Garrard 2025 T/C with 
Sonotone 9TAHC 
Diamond Cartridge 
Garrard 2025 T/C with 
Sonotone 9TAHC 
Diamond Cartridge 
ready wired in teak plinth 
with cover 



£8-97 
£1400 



Carriage and Insurance 50p extra any 
item. 



SP25 MKIII SPECIAL! 



riAB&ABD SP25 mk ni 

SINGLE RECORD 
PLAYER FITTED 
GOLDRING 650 or AT66 
MAGNETIC STEREO 
CARTRIDGE as avail- 
able. COMPLETE IN 
TEAK PLINTH WITH 
RIGID PER8PEX 

COVER. 

Total list pries over £29. 
PREMIER PRICK 

£19 90 




HI-FI STEREO 
HEADPHONES 

Designed to the highest 
possible standard. Fitted 
■JJIn speaker units with 
soft padded ear muffs. 
Adjustable headband. 
8 ohms impedance. Com- 
plete with 6ft lead and 
stereo jack plug. 

FP. * 
26p. 
STEREO STETHOSCOPE SET Low Imp. £1.25 

P. ft P. lOp 
MONO 8TETHOSCOPE SET low Imp. 52p. P. ft P. lOp. 




E.M.I. 13x8in. 
HI-FI SPEAKERS 

Fitted two 2iln tweeters and 
crossover network. Impedance 
8 or 15 ohm. Handling capa- 
city WW. Brand new. 

£3.4 7 P.*P.40p 




WELLEB "EXPERT" SOLDER 

uDsT. Saves time and simplifies 

soldering in the home and service 

iept. Two posit ion trigger gives Instant 

30p 



watt. 240 volt A.C. 



-Marks man" Soldering Iron. Lightweight 
A" pencil bit. Ideal for regular bench use 
and around the home. 25 watts. 240 volt 
A.C.sl50P*P15p 



VERITAS V-149 MIXER 

Battery operated 4-channel audio mixer providing four 
separate Inputs. Blze 6 v 3 x 2m. suitable for crystal micro- 
phone low impedance micro- 
phone, with transformer, 
radio, tape, etc. Max, Input 
1-Bv. Mad. output 2-5v. Gam 
8 dB. Standard Jack plug 
socket inputs, phonoplugs 
output. Attractive teak 
wood gram finish ease. 



hoio ro 

MODEL *»«* 




nop c"K 47 

MODEL «wO»*M 



P. ft P. 12p 




TAPE CASSETTES 

C60 (£L) 37p 



mln., 

<gj 62p 



C90 

C120 (S5.) 87p 



3 for 
CI.S5 

J for 



P. ft P. 6p. 

FREE CASSETTE HEAD CLEANER with 

every 10 cassettes purchased. 
All cassettes con be supplied with library cases 
at 3p. extra each 



"VERITONE" RECORDING TAPE 

SPECIALLY KAHUFACTURED W TLS.A. FROH EXTRA STROUD 
PRE-STRETCHED MATERIAL. THE QUALITY IS UNEQUALLED. 
TEN81LISED to ensure the meet permanent base. Highly resistant to break- 
age, moisture, heat, cold or humidity. High polished splice free finish. Smooth 
output throughout the entire audio range. Double wrapped-attractively boxed 

LPS 8* 250' P.V.0. 28p DT6 61' 1800' POLYESTER f 1-18 

TT8 8' 450' POLYESTER 87p TT8 51' 2400' P0LYE8TER fl 87 
DT3 : F 600' POLYESTER 57p SP7 7' 1200* P.V.C. 62p 



SP5 
LPS 
DT5 



600' 

6' 900' P.V.C. 
6* 1200' POLYESTER 



489 
60p 
75p 



LP7 

DT7 
TT7 



1800' ACETATE 75p 

2400' POLYESTER £ 1 25 
3800' POLYESTER tZ 50 



TAPE SPOOLS 3" 5p, 5*. 5J'. 7* 8p, 

Post and Packing 3" op. 5*. 61*, 8p. 7* lOp. (3 reels and over Post Free). 




— Wt 

10 & 23, TOTTENHAM COURT ROAD, LONDON, W.1 TEL: 01-636 3451/2639 1 ?m 

HEAD OFFICE & MAILORDER DEPT. 23.TOTTENHAM CT. RD. TEL.01-636 3451 ' ' °° 



691 



PROFESSIONAL RECEIVERS 

SUPPLIED TO GOVT. DEPTS., 

INDUSTRY, LABORATORIES, 

RADIO & T.V. AUTHORITIES, ETC. 



BUY DIRECT AT PRICES 15% 
BELOW RETAIL VALUES 




ffifUULj 

is a high quality 

COMMUNICATIONS 

RECEIVER 

(replaces NA 50I8A) 

Recommended Price 
£42. 0. 

!jg £37-80 



(Cash only) plus 62p p. & p Complete with 
standard batteries and earpiece. BFO 
(optional extra) add £1.75. 

IT NOT ONLY RECEIVES Aircraft, 
Shipping (VHF & SW), Taxis. Ambu- 
lances, Fire Service, T.V. Sound, Hams, 
Gas and Electric Boards, Public Services 
and many other radio telephone 
mobiles — BUT ALSO Classical Music, 
Pop and all that Jazz. 

The MPR 3065 is a communications receiver 
and entertainment source in one neat, 
transistorised, portable package. Features 
a colour coded illuminated tuning dial and 
band selector, AFC, squelch, BFO (optional 
extra), large speaker. Ext. Aerial Socket. 
Works off mains or batteries. Size: 1 0± x 7± x 4 
inches. 22 Transistors/Diodes. 

FREQUENCIES: Medium Wave, 540- 
1600 Kcs.: Marine, 1-6-4 6 Mcs. ; FM/VHF. 
B8-I08 Mes. : Aircraft, 108-136 Mcs. 
(Military, Civil and Ground control) ; High 
VHF./PB, 146-176 Mcs. (Commercial and 
Industrial RT mobiles). 



MODEL MPR 3016 6 BAND 




SAME BANDS & FREQUENCIES AS MODEL 
MPR 3065 PLUS ADDED FEATURE OF 
SW 5-0— 12 OMcs (with Fine Tuner). Plus 
62if> PIP. 

BATTS & EARPIECE INCL. 

Styled in elegant black case with luxury 
Chrome trim, soft padded speaker grille, 
die-cast sides and walnut insert. Size BJ" x 1 1" 
x 3J". Wt. 51 bs. approx. 

Enclose 5d. scamp for reply. Trade supplied. 



NEW 1 From "Lafayette" 4 band T.V. sound 
Battery portable with PB mobile band (146- 
176MHz). 



TV SOUND CHANNELS 2-13. VHF/FM 
Local & National Radios. PSB RT Mobiles. 



OUR PRICE £27.95 plus SOp P/P. 
Complete with Batteries, Earpiece, Circ. 
Diagram, AC Adaptor Socket; External 
Aerial Socket. 



STOCKTON PARTNERS (Dept.p.w.) 

Importers and Distributors 

Brighowgate, Grimsby, Lines. 

Tel. 0472 64196/58815 



LOOK AT THESE PRICES 

CARTRIDGES 

Acos OP67-2, GP91-3SC £1-12, ; ACM (JP93-1 

£1 381 ; Acos OP94-1 £1-82} : Sonotoue 9TAHC 

£1 97(. All above In makers" cartons. B8R X4H 

£160. 

THIS MONTH'S 8PECIAL OFFER 
Oarrard SP25 Mk. Ill with KS4UA cartridge. 
In good quality teak plinth with perapex dim 
cover. Complete with all leads ready tu use £20. 
BFB6 Mk. Ill deck only lew cartridge £32-87. 

PLDGS & SOCKETS 

Phono plugs, assort**! colours 4)p : 4Sp per doz. : 
Coaxial plugs, aluminium 7Jp; Coaxial couplers 7Jp: 
2 pin DIN plugs 15p; 3 pin DIN plugs 15p; S pin 
DIN plugs 17p; 2 pin, 3 pin A 5 pin DIN sockets 71p ; 
Wander pings 2)p; wickets Ziv: llanana plugs Sip: 
Sockets 6p; 3-fimm J/Plugs 7Jp and 12|p; Standaid 
J/Piugs with solder terminals lOp : Chrome 15p : 
8lde Entry J/Plugn black and chrome 24p; Insulateil 
i/soekets — o/cct 20p. c/cct 17p. 

ELECTROLTTIC CAPACITORS 
4uF lBOv 4p ; 8ul-' fiOOv 15p ; IOuF ISOv 4p ; 
12uP 2Bv 4p ; 18uF 4B0v 14p ; lllub" + lBnT 
4B0v 23Jp : 30uF lOv 4p : OOuF 10* 4p ; 
lOiluK in- 4p ; lOOuF 12v 4p : ISfluF 12v 4p ; 
loOOuF 30v 18p; IOuF 16v 7i«: SOuOuP 2Sv 60p: 
lO.OOOuF S6v 76p ; 20.000uF 30v £106. 

MICROPHONES 

Acos Mlc 43 £1-12} ; Acos Mic U0 1)11 ii Planet 

CM70 £1-60 ; Hand Mike 75p. 

VALVES 

PY81 36p : PCL82 39p; F.lMS.1_46p : KFIH-I 45p 

Postage extra. 

GEORGE FRANCIS (Oept PW), 

12-14, MIDDLE GATE. HEW ARK. NOTTS 
Telephone : Newark 4783. 




MMNSUMTSfon 

mtli" a/l types of 

TRANSISTOR £ QUI PMC NT 



RUN YOUR TAPE 
RECORDER OFF 
A.C. MAINS 

Mains unit supplied com- 
plete and ready to plug 
Into your cassette re- 
corder. (State voltage, 
model and plug required.) 

£2-50 p. *p. isp 



12 VOLT CAR BATTERY UNIT 

Enables you to run your cassette recorder off 12V. 
car battery. (State 6v or 7iv output, model and plug 
required.) £2.Q0 p. 4 P . , 5o 

PLUS-3 
MAINS UNIT 

Provides three separate 
switched output voltages 
6v., 7;v. and9v. DC. attrac- 
tive case with indicator 
light, mains lead output 
socket, plug and lead. 
Size Ai x 3i x 2* In. 

£3-00 p- & p. isp. 

MAINS UNIT FOR 

ALL TRANSISTOR 

RADIOS, ETC., USING 

PP3 TYPE BATTERY. (ALSO #?•€ .1 C P. 4 P. 

AVAILABLE FOR 6V.) *1 * I i 0p . 

MAIN UNITS 

For single outputs, 6v, 9v, 12v. 18v, £2.00. 
For two separate outputs, 44v 4- 4-ta, 
6v + 6v„ fiv + 9v, £2.50. P. & P. 15p. 
per unit. (Please slate outputs read). 

All unite are completely Isolated from 
mains by double wound transformer 
ensuring 100% safety. 

R.C.S. PRODUCTS (RADIO) LTD. 

(D.pt. P.W.), 31 Oliver Road, London, E.17 




Extra leao with plug to tit 
your cassette recorder 
50p. (State model and 
plug required.) 




STROBE! ■ STROBE! 



Build a SiroCe Unit, using tne latest type 
Xenon white light flash tube. Solid state timing 
and triggering circuit. 230,240V a.c. operation. 
EXPERIMENTERS' ECONOMY KIT 
Speed adjustable I to 36 Flash per sec. All 
electronic components including Veroboard 
S.C.R. Unijunction Xenon Tube and instructions 
£6 30 plus 25p P. & P. 
NEW INDUSTRIAL KIT 

Ideally suitable for schools, laboratories, etc. 
Roller tin printed circuit. New trigger coil, 
plastic thyristor. Speed adjustable 1-80 f.p.s. 
Price £10 50. P. & P. 50p. 

HY-LYGHT STROBE MK III 

This strobe has been designed and produced 
for use in large rooms, halls and the photo- 
graphic field, and utilizes a silica plug-in tube 
for longer life expectancy, printed circuit for 
easy assembly, also a special trigger coil and 
output capacitor. Speed adjustable 0-30 f.p.s. 
Light output approx. 4 joules. Price £12-00 
r. & P. 50p. 

SPECIALLY DESIGNED FULLY 
VENTILATED METAL CASE 
including reflector. £4 00. P. & P. 45p Post 
Paid with kits. 

AND NOW! 

THE 'SUPER' HY-LYGHT KIT 

Approx, four times the light output of our well 

proven Hy-Lyght strobe 

9 Heavy duty power supply. 

• Variable speed from 1-23 flash per sec. 

Fantastic Octal based tube with massive 

electrodes. 
Reactor control circuit producing an 

intense white light. 
The brilliant light output of the SUPER" 
HY-LYGHT gives fabulous effects with colour 
filters. 

Never before a Strobe Kit with so HIGH an 
output at so LOW a price. ONLY £20 plus. 
75p P. & P. 

ATTRACTIVE, ROBUST, FULLY 
VENTILATED METAL CASE 
specially designed for the Hy-Lyght Kit. 
Including reflector £7 00. P. & P. 45p. 
7-inch POLISHED REFLECTOR 
Ideally suited for above Strobe kits. Price 53p. 
P. & P. I3p or post paid with kits. 



VENNER ELECTRIC 
TIME SWITCH 

200/250V Ex. GPO. Tested. 
Manually set 2 on, 2 off every 24h. . T ., 

Override switch: I0A £2-75, I5A \jkj 

£3 25, 20A £3-75. P. & P. 20p. O* 

Also available with solar dial ON 
dusk. OFF dawn. Price as above. 



$S 



12 VOLT DC MOTOR 

Powerful I amp. 

VERSIBLE motor. 

3,750 RPM con 

with external gear train 

(removable) giving final speed 

1 25 RPM. Size: 4," x 2,' dia. Price 95p 




ELECTRONIC 
ORGAN KIT 

Easy to build. Solid State. Two full octave 
(less sharps and flats). Fitted hardwood case. 
Powered by two penlite l|V batteries. Complete 
set of parts including speaker etc., together 
with full instructions and 10 tunes. Price £300. 
P. & P. 22p. 

50 in I ELECTRONIC PROJECT KIT 
50 easy to build Projects. No soldering, no 
special tools required. The kit includes Speaker, 
Meter, Relay, Transformer, plus a host of other 
components and a 56-page instruction leaflet. 
Some examples of the 50 possible Projects are: 
Sound Level Meter. 2 Transistor Radio, 
Amplifier, etc. Price £7-75. P. & P. 30p. 

CRYSTAL RADIO KIT 
Complete set of parts, including Crystal 
Diode, Ferrite Aerial, Drilled Chassis, and 
Personal Ear Piece. No soldering, easy to build, 
full step by step instructions. £1-75 inc. post. 



LOW POWER UHF TRANSMITTER 

In useful black crackle 
finished metal case. 
Size 94-' x 5' x 2+". 
Contains, one I2v LT 



:r, one 




38-334 MHz crystal 
multiplier stage con- 
taining, three OCI70, 
one AFI86. RF output, mains neon, SP toggle, 
miniature fuse holder etc. etc. Sold for com- 
ponents only, rearet no data available on this 
device. A BARGAIN at 80o olus 30o P & P. 



■HJi.'JHiUiM.IIJliM 



All Mail Orders. Also Callers. Parting Space 

Dept. PWI2. 57 BRIDGMAN ROAD, 
LONDON, W4 5BB. Phone 01-995 1560. 

Showrooms now open. Mon.-Fri. 



Personal Callers only. Open SAT. 

9 LITTLE NEWPORT ST. 

LONDON. WC2H 7JJ 01-437 0576. 



692 




pO\A/EP 



THE power supply described uses the same feed- 
back principles as in closed loop control 
systems and is capable of delivering 1A at any 
voltage between 4V and 20V. A separate 45V d.c. 
output is also available making the power supply 
particularly suitable for audio amplifier work where 
good regulation is required for the low voltage pre- 
amplifier stages and a higher d.c. supply required 
for the power output stage, generally of the order 
of 45V, the regulation of this not being so critical. 
Three pairs of sockets for the regulated output 
have been provided to enable the power supply to 
supply several loads with the minimum of incon- 
venience. These outputs have been left floating and 
a separate earth socket provided such that the supply 
can be connected to give a positive output with res- 
pect to earth or a negative output with respect to 
earth. The negative output of the 45V supply is con- 
nected in common with the negative output of the 
regulated supply. 

Variable current limiting from 0-2A to 1A is 
included making the power supply particularly suit- 
able for development work and also giving it protec- 
tion from short-circuit surges. 



Principle 

The principle of negative feedback is used in 
systems where accurate control is required. The sys- 
tem could be a positional servo as used in rudder 



Unregulated 
input 



Current 
output 
stage 



Constant 

current 

generator 



Reference 
voltage 



Output 
current 
sampler 



Current flow during 
limiting only 



Negative feedback 
loop 




Regulated 
output 



Differential 
amplifier 



Output 
voltage 
sampler 



UIMH" 

A. BURNETT 



Fig. 1 : Block diagram showing function of stages in the power unit. 



control of a model aircraft, speed control of an elec- 
tric motor, temperature control of a blast furnace or 
cooker or as in this example, voltage stabilisation. In 
each case a sample is taken of the final output, a 
comparison made with some reference, then correc- 
tive adjustments made to reduce the error. 

The block diagram of Fig. 1 illustrates the prin- 
ciple of voltage control where the controlling device 
is in series with the output current. The output is 
monitored by a sampler and the sample voltage com- 
pared to a reference voltage by a differential ampli- 
fier. 

The differential amplifier amplifies the difference 
such as to starve the output stage of base current if 
the sample voltage is greater than the reference. As 
a transistor is basically a current amplifying device 
complete control of the output current can be 
achieved by controlling the base current of the 
current output transistor. 

Current Output Stage 

Transistors are current amplifying devices and in 
general the more current they are capable of 
handling the less gain they have. A power transistor 
capable of passing 1A can have a typical /3 (current 
gain) of only 10 which would mean that the base cur- 
rent would still be rather high for the differential 
amplifier to handle, being in the region of 100mA. 
The current output stage is simply a configuration of 
two transistors, Tr3 and Tr4, Fig. 2, to give high out- 
put current capability with high current gain. 



Constant Current Generator 

The output current of this circuit, Tr2, is constant 
and sufficient to supply the maximum base current of 
the current output stage with a little extra for the 
differential amplifier. 

The circuit uses the principle that as the base- 
emitter junction of a transistor is a forward biased 
diode then it will present a low voltage drop (0-7V 
in the case of silicon transistors). The zener diode 
potential will therefore be applied almost completely 
across R6. The resulting current through R6 : — 

I-(V,-0«7)/B6 
will pass through the transistor without loading the 
zener diode. 

693 




Fig. 2: Circuit of power unit. The diodes D1-4 may be replaced by a single bridge rectifier unit. 



Bias current for the zener diode will be supplied 
by R6. A constant current output of 4mA was suffi- 
cient to supply the output stage and the differential 
amplifier. 



Differential Amplifier 



The differential amplifier, Trl and Tr€, is coupled 
to the base current circuitry of the current output 



Voltmeter 



Neon 



rteon / C\ 



Ammeter 



Current Voltage 

limit (coarse) 



Voltage 
(fine) 



i o o y 




stage. It takes current surplus to that required to 
maintain the correct amount of output current. 

The amplifier amplifies the difference between its 
two inputs hence the term "differential amplifier." 
In this case it is used as a current control device. 



Reference Voltage 

This is obtained from a zener 
diode, D5, an attempt being made 
to keep the diode current constant 
by connecting a capacitor across it. 
This is necessary as low wattage 
zener diodes have a high series 
internal resistance resulting in 
their output voltage varying with 
current. 

The regulated output voltage of 
the power supply would normally 
be preferred to supply bias current 
to the zener but as this will be 
switched over wide ranges in this 
case, bias current has been 
supplied from the unregulated 
input through a 4-7kQ resistor R2 
giving a bias current of 10mA. 



Heat sink 



Fig. 3. Layout of unit constructed by the author. 
See Fig. 4: for details of the component 
board. 



694 



EVERYTHING BRAND NEW 
AND TO SPECIFICATION 

No surplus, clearance lines or 
manufacturers* seconds. 



ELECTROVALUE 

Electronic Component 
Specialists 



SEMI-CONDUCTORS 

All power types with 
free insulating sets 







AC142H 


25p 


8D131 


79p 




lOp 


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29p 








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22p 










60176 


16p 










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i 37p 1 BT)130 


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NEW LOW PRICE OFFER!! 



PEAK SOUND EKGLEFIELD 84<V. AMPLIFIER 
20-20 watt R.M.8. into 8 CI speakers. Unique add-in 
facility lor FM stereo tuner, and other original fea- 
tures. A de-luxe job in every way. Maker's B.B.P. 
£49 -50. From Electrovalue, : 
(Carr. <(- Packimj to 
nttyirhrrr ;,i f'.K. iddlnp) 



£3375 



Add good appearance to your building 

SIEMENS 
CAPACITORS 




These electrolyte capacitors are all in the 
same style and colour and greatly enhance 
the appeiirance of the finished article when 
built. With, axial leads and clearly marked 
polarity. 



for full list of more than 60 value 

SIEMENS TTL I.Cs— wW» r»"Ke in stock at an all time low in prices. 



Advertisement 
No. PW62A 



DISCOUNTS 

10 \. discount is allowed on orders 
'or £6 to £15 in value. 

15 "o discount allowed on orders 
over £15. No discount on ilemi 
mar kid yell. Prices subject to 
alteration without notice. 



CATALOGUE 

The latest (1971) Electrovalue 
catalogue contains 84 pages packed 
with hundreds o! items and valuable 
illustrated information. Post Iree 
lOp. 



RESISTORS 1 0% - 5% - 2% 



Code Power Tole 



Range Value 



illlMl 



1 to il 10 to 99 100 up 

(see note below) 






l/'OW 





1/SW 


c 


1/4 W 





1/>\V 


c 


1W 


MO 


1/2W 




1W 


WW 


3W 


WW 


7W 



fl% 82-220K E12 9 8. 

6% 4 7-470K B24 I 0-8 0-, 

10% 47-10M E12 1 0-8 0-7 

6% 4-7-10M E24 12 I 0-9 

6% 4-7- 10M E12 2-3 9 19 

2% 10-1M E24 4 35 

10% ±1/20 Q 0-22-3-9 E18 7 •_ 

6% IS-10K E12 7 < 

6% 12-10K E12 « 9 » 

Codes : C= carbon film high stability low noise 

MO — metal oxide Electrosii TR5 ultra low noise 
WW wire wound Plcssey 

E*2°d*n(iles series: 10, 12, 15, 18, 22. 27. 33, 39, 47, 56, 68. 82 and their decades 
E24: as SIS plus 11. 13. 16. 20. 24. 30. 36. 43. 51. 62, 72, 91 and their decades. 
Prices ar» ffl pence cadi for name ohmic value and pmr.r rating, SOT mitcd valuei. 
(Ignore .fractions of \p on total value of resistor order). 



AMPLIFIERS 

80 WATT BAILEY PARTS 

Transistors and PCB for one 

channel £6 46 

Capacitors, resistors (metal Oxide), 

and transistors, one channel. £8-41 

Ootoplete unregulated power 

supply pack. £4-75 

Suitable heatsink 10DX400C. 55p 

MAIHLIHE KITS 

70W. £12 60 nett. (main amplifier 

module). 

Power supply kit £600 nett 
Suitable pre-amp kit £6-25 nett 
(less chassis & panel) 

MULLARD UHILEX SYSTEM 
EP9000 Output module £2-90 nett 
F.F9001 Pre-amp module £310 nett 
EP9002 Power supply unit £4-80 
nett. 
Control unit assembly £800 nett. 



MULLARD polyester C280 series 

250V 20% 001: 0022; 0033. 0047 Sp ea. 0068; 
01, 016 4p, 022 5p. 10%: 0-33 7p, 0-47 8p. 0-68 lip, 
liiF 14p. l-5(iF 21p,2-2fiF 24p. 



MULLARD SUB-MIN ELECTROLYTIC 

C426 rar-ge axial lead 6p each 

Values (iiF.V): 64 64: 1/40: 1-6/25; 2 5.16; 2-5/64: 4/10; 
4/40; 5/e4; 6-4/6-4; 6-4/25: 8/4; 8 40; 10 2-5: 10,16; 10/64; 
12-5/25; 16/40: 20/16; 20/64; 25/6-4; 25 .25: 32,4: 32 10: 
32/40; 82/64: 40/16; 40/2-5: 80/6-4; 50/25; 50/40: 64/4: 
64/10; HO/2-6; 80/16: 80/25: 100/6-4; 125/4; 125/10: 
125/16: 16679-6; 200/6-4; 200/10; 230/4; 320/2-5; 320/6-4: 
400/4; 500/9 -5. 



LARGE CAPACITORS 

High ripple current tvpes: 10O0/2B 28p: 1000/50 41p; 
1000/lOt 82p. 2000/25 S7p; 2000/50 67p: 2000/100 £1-44: 
2500/04 77p: 2300/70 98p: 5000/25 62p; 5000/50 £110: 
5000/100 £2-91: 10000/50 £2-40. 



SIEMENS' 5% TOLERANCE 
POLYCARBONATE CAPACITORS 

260V up to OlmP, 100V 0-lmF and above. 
001. 012, 0-015, 0018, 0022, 0027 5p 
0033, 0047, 0056, 0068, 0081, 001. 01 to 0-22 Op. 
0-33. 39. 9p. 0-47. lOp. 0-56. 18p, 6b, 16p. 



S-DeCS 



Manufacturer's prices Increase roug/ilv by 20% on these on 
panes SI, SI and S3 sinee print ino i/iir catalogue. S-DeC 
£1-44, lour pack £5-10. DeCSTOR pack £2-88. T-B-ec, 
may be temijcraturc-cycled (208 points), £2-88. /xDccA, 
£8-18. LBecB, £5-94. Also I.C. carriers. 



ZENER DIODES 



6% fill range E24 values: 400mW: 2-7V to 30V 15p each 
1W: 6-8V to 82V 27p each 1-6W: 4-7V to 76V 60n each 
Clip to increase 1-5W rating to 3 watts (type 206F) 4p. 



CARBON TRACK 
POTENTIOMETERS, long spindles 

Double wiper ensures minimum noise level. 

Single gang linear 100 fi, to 2-2M Q 1»P 

Single gang log 4-7K £1 to 2-2M CI 12P 

Dual gniig linear 4-7K £1 to 2-2MC1 42p 

Dual gang log 4-7Knto2 2Mfl 42p 

Log/antllog 10K. 47K. lMfJ only 42p 

Any type with }A D.P. mains switch, extra 12p 

Please note: onlu decades of 10- 22 and 47 are acailablt 
uithin ranges quoted. 



CARBON SKELETON PRE-SETS 

Small high qnalitv, type PR. linear only 100 CI. 220 il 
470 n. 1 K. 2K2, 4'K7,'lOK, 22K. 47K. 100K. 220K. 470K. 
1M. ■_'M'J, 5M, 10MQ Vertical or horizontal mounting 5p 
each. 



Handbook ol transistor equivalent and substitutes, 40p. 
(Postage 3p if ordered alone). 



POSTAGE AND PACKING 

Free on orders over £2. Please add lop It orders under £2. 
Overseas orders welcome: carriage and insurance charg- 
ed at cost. 

TJ.S.A. CUSTOMERS are Invited to contact ELECTRO- 
VALUE AMERICA, P.O. Box 27, Swarthmorc, PA 19081 
for special prices 




(Dept. PW.1271) 28 ST. JUDES ROAD, ENGLEFIELD GREEN, EGHAM, SURREY 

Hours: 9—5.30: Sat. 1 p.m. Tel.: Egham 5533 & 4757 (STD 0784-3) Telex 264475 



695 




SPEAKER MATCHING 



ZS^^&S»JS1SS&^SSS^^SS^^- JBltEMi TRANSFORMERS 



We still do die well known Shelley and Carton column speaker systems. 




STEREO HEADPHONE 
JUNCTION BOX 

Simple unit connects direct to amplifier and 
speakers to give attenuated headphone out- 
put, has 2 position switch to jive headphones 
only — speakers only. 
Only £1-50 each P& P 124. 



CARTRIDGES-Stereo 

Sonotone9TAH/C Diamond £2.40. Ronette SI05 Medium 

£ ft r&ft ! ,06 u" ,,h SPS&JH"* AcOS GP93/I Sapphire. 
CI .90. GP94 I Sapphire. £2. TA700 equivalent to B.S.R. SXIM 
CI.75. Japanese equivalent to B.S.R. TC8s, £1.75. P. & P 7no 

on each. r 



3. 7. IS ohms. 
10 watt. 70np. P. & p. |7np. 



VYNAIR 

Widths from SO to 54 in., 75np yd. off roll 
P. & P. lOnp. i yard 40np. P. & P. I0np. 
Send 5np stamps for samples. 




IMP 

Wedge shaped extension 
speaker 7\ x 6, x 4in. 
(max.). Coverec in wal- 
nut wood grain cloth 
with mottled Vynair front. 
Keyhole slot at back. Fitted 
with 3 ohm speaker unit. Only 
£1.25. P. & P. 36np each 




DUDLEY 

II* x »4" x 5* deep, tapering to 31" 
deep covered in Black reseine and 
Mottled fawn Vynair £2-10 P & P 25p. 



SPEAKERS 

E.M.I. 134 x 8in, 3 ohm £2.50. IS ohm. P. & P. 30np. E.M I 
F m iri o- tW f.c ii T: tw !?- te . r »- IS ohm £4.50. P. & P. 30np! 
Lklr, ?L *&"• (l5 o° hm 2 HJ-Fi quality £6.25. P. & P. 30np. 
Bakers 12m. 25 watt 8 and 15 ohms CT. P. & p. 30np. Eagle 
Crossover 86np. P. & P. 5np. B 



CARTRIDGES-Mono 

GP.9I Stereo Compatible £1.2!. Acos 
GP67/2 will replace Collaro and Garrard 
Mono cartridges, 95np. T.T.C. Crystal 
High Gain, 75np. B.S.R. TC6H Jap. 
equivalent £1.25. P. & P. 7np. 



FARRADAY 

5J* x II* x 4}" 

covered in White, 
Green or Black 
rexine or Teak cloth 
with Silver coloured 
metal front 
£2-90 P& P25p. 





CLARENCE 

II" wide x 84" 
x 44" deep with 
volume control 
covered in Black 
rexine and Mott- 
led Vynair. 
£2-25 P & P 25p. 



NOCTURNE 73 STEREO SYSTEM 




BROADWAY ELECTRONICS 'd^TI ROAD TOOT,NG br °*°wav. london ».*.« »«. ** 



(Nr. Tooting Broadway Underground Station) 



(Closed all 
Wednesday) 




RSGB BOOKS FOR YOU 



RSGB AMATEUR RADIO 
CALL BOOK 

1972 edition now available 

Includes details of new calls notified by the M.P.T. 
up to August 1971, and contains over 2,600 amend- 
ments to entries in the 1971 edition. 
128 P a 9es. 57p po8t paid 

VHF-UHF MANUAL 

By G. R. Jessop, C Eng, MiERE, G6JP 

2nd edition. Considerably enlarged and revised. 

Transmitters, receivers and test equipment for use at 
vhf and uhf are all fully covered on a practical basis 
in this new edition. £1 -80 post paid 

RADIO COMMUNICATION 
HANDBOOK 

832 pages of everything in the science of radio com- 
munication. The Handbook's U.K. origin ensures 
easy availability of components. Complete coverage 
of the technical and constructional fields. A superb 
hard-bound volume. £3.50 pos t paid 

These are three of a complete range of technical 
publications, log books and maps, all obtainable from : 

RADIO SOCIETY of GREAT BRITAIN 



35 DOUGHTY STREET, LONDON, WC1N 2AE 



PADGETTS RADIO STORE 

OLD TOWN HALL, LIVERSEDGE, 

YORKS 

TEL HECKMONDWIKE 4285 

Latest Air Ministry Release. Radio Receiver Type R4187. 2-8 to 18 M.H.Z. In 
Three Bands. Complete with 17 Miniature Valves. 28 Volt Motor Power Supply 
Motor and Manually Tumid. Very Clean Condition but not tested. £5. Carriage 
and Insurance 75p. 

Control Unit Type 4190. Complete with Three Miniature Valves It- 500 U.A. 
Meter, Six Relays, Modei Makers Motor with Gears. 24 Press Buttons, lots ot 
Spares. Very Clean condition. £1 50. Carriage and Insurance 75p. 

Autostabllisor Amplifier Unit. Complete with Carpenter Relay and Base. Many 
Spares. 50p. P/P 33p. 

Brand New 'Manufacturers Surplus Mains Transformers 250-0 250 80M.A. 8-3 

R ??, ,a i! ned Tv - Tubes. All with 12 Months Guarantee. 

AW43 88 £2. AW43/80 :£1 50. MW43/69 £1. 

Special Offer Brand New 3rimar Tubes. C17P.M. CI. Many older Types in Slock. 

Carriage and Insurance on any Tube £1-10. 

Breaking up Ferguson Model 506T. Tested L.O.P.T. £1-45 post paid. 
Fireball Tuner Unit with valves, less knobs, 75p post paid. 
S.A.E. for Price List of other Spares. 

G.P.O. Relays Ex Units. 400 Ohms and 600 Ohms. 50p doz. P/P25p. Sample 
Relay op P/P 5p. 

Miniature Lamp Holder, Brass. lOp P/P 5p. Ooz. Lots Mp Post Paid. Base 
Soar a Type. 

Ta S 'e'l2t" ,y TaPeS ' 7 LP ' 7 ° P ' 7 " St ' Mp 5 ' L P " 50p - 5 ' St - Wp P/P on any 
Jap Personal Ear Pieces. Large Plug 10p Post Paid. 

Valve List Ex Equipment All Valves Tested on a Mullard Valve tester before 
Despatched. 3 Months Giarantee on all Valves. Single Valves P/P 3p. Over three 
valves rir Palo. 



ARP12 

EB91 

EF85 

EBF80 

EBF89 

ECC81 

ECC82 

ECC83 

ECL80 

EF80 

EF91 

EY86 



Sp 


PCC84 


4p 


PCF80 


12*P 


PCL82 


12tp 


PCL83 


12{p 


PCF82 




PL36 


12fp 


PL81 


mp 


PY81 


7+P 


PY33 


7*p 


PY82 


4p 


PL82 


20p 


PL83 




PCL84 



5p 


U191 


5p 


U251 


12+P 
«fp 


6BW7 


6U4 


12ip 


6F23 


20p 


20P1 


17ip 


20P3 


7fp 


20D1 


17tp 


30P4 


7{p 


30P12 


7+P 


30FL1 


7*P 
12ip 







20p 
12+p 
lOp 

10p 
20p 
20p 

lOp 

10p 
20p 

20p 

20p 
2IP 



696 



Output Sampler 

The resistor chain is strapped across the output 
voltage and the tapping point will always be at 3-9V. 
There are three separate resistor chains in order to 
reduce the sensitivity of VR1. 

It is worth mentioning that the output of this power 
supply can never be less than the reference voltage 
generated by D5. If 3-9V is not low enough then a 
2-7V zener may be used for D5 and if necessary, the 
sampling chain recalculated. 



Construction 

Not much information need be given on the con- 
struction of this unit since much will depend upon 
the dimensions of the components used. Fig. 4 shows 
the layout of the component board and the inter- 
connections with the remaining components. 

Fig. 3 illustrates the general layout of the power 
unit as built by the author. Note that the transistor 
case of Tr3 forms the collector connection and must 
be insulated from the heat sink with the mica insula- 
tion kit generally supplied with the transistor. Check 
after assembling the transistor and heat sink that 
there is no conducting path between the transistor 
case and the heat sink. 

The heat sink used here is made from aluminium 
sheet 4 1 2X2 3 4in. bolted to the main chassis. 

It is worth adding that where wire-wound resistors 
are used there is always a tendency for oscillation to 
occur. These resistors, from the nature of their con- 
struction, are slightly inductive. Often this effect can 



* components list 



Resistors 

R1 osti- 
tis a -mi 

R3 39W2 
2-2kl2 
4-7K12 
tfeft 



R7 3901 i 



R4 
R5 
R6 



R13 1kl2 
R14 4-7kQ 
: R15 3301? 

3W R16 4700 
! R17 1-2ki2 

! . R18 270RO- 






All resistors except RIG are ^W 
VR1 50011 linear carbon pot 
VR2 1kQ linear carbon pot 

Capacitors 

C1 25C%F 64V C2 10/* F 25V 
C3 22pF polystyrene 

Semiconductors 

Tr1 2N706 or BC107, 2N930 or 2N2484 

Tr2 2N3250or BCY30, 31, 32 or 2N3250 

Tr3 2N3055 or BOY 38, with insulating was 

Tr4 BFY50 or 2N1711, 1613 or BFY51 

Tr5 2N706 or BC107, 2N930 or 2N2484 

Tr6 2N706 or BC107, 2N930 or 2N2484 

D1 1N645 D4 1N645 

D2 1N645 D5 ZF3-9(400mW) 

D3 1N645 D6 ZF4-7 (400mW) 



Miscellaneous 

Transformer 30V 2A (Type MT3AT). SI, 2 pole 
2 way toggle switch. S2, 4 pole 3 way, make before 
break wa'fer switch, used as 2 pole 3 way. Sockets, 
red (4), black (5). Neon lamp, Q1332 (Bulgin) or 
equivalent; some equivalents have built-in resistor 
—if so delete R18. Fuse holder with 1A fuse. Vevo- 
board, plain, Zi x 3f in., 0-1 in. matrix. Aluminium 
chassis, 10* x 9 in,, panel 12 x 9 in., heat sink 4| x 
2J in. Voltmeter 20V, ammeter 1A, if required. 





VR2 



o/pl 

Tr3 unregulated 

Fig. 4: Layout of component board. 



be corrected by the addition of a small capacitor of 
20 to lOOpF coupled across the resistor to tune out 
the effect of the inductance. ■ 



TELEVISION 



DECEMBER ISSUE 

A CLOSER LOOK AT PAL 

The basic principles of the PAL system are now 
generally understood. There is however a good deal 
more than meets the eye to the system. So this month 
we are starting a new series in which we shall be 
investigating the system in greater detail than pre- 
viously. The account will be descriptive, not a fog of 
formulae! 

CONSTRUCTORS' CIRCUITS 

This month we turn to the line timebase. A choice of 
transistor or valve line oscillator circuits, both with 
flywheel synchronisation, and a line output stage with 
optional stabilisation and optional solid-state e.h.t. 
and boost rectifier circuits is given. 

THE TELDEC SYSTEM 

With the first demonstration of the Teldec system in 
colour at the recent international Berlin Radio Exhibi- 
tion this remarkable disc videorecording system is 
again in the news. A full account of the mechanics 
of the system. 

RUSSIAN TV RECEIVERS 

There are many novel and unusual features in the 
Temp single-standard receivers manufactured in the 
USSR and now being widely distributed in the UK. 
For example, an external definition control varies the 
vision i.f. response by means of a varicap diode, the 
line blocking oscillator transformer has an adjustable 
feed-in point for optimum a.f.c, automatic brightness 
control is incorporated in the video output stage and 
amplified negative feedback is used in the field output 
stage. We are taking a detailed look at this interesting 
chassis. 

PLUS ALL THE REGULAR FEATURES 

ON SALE NOVEMBER 22 



697 







deliberate effort has to be made to roll-off this 
response to avoid r.f. pickup in the high gain 
amplifier and also to prevent the bias oscillator signal 
from being a problem. 

It should be pointed out that this circuit is only 
suitable for the Marriott XRP18 or XRP36 record 
playback heads and the XES11 erase head. The 
amplifier will play back from other heads but, on 
record, other heads need much higher bias voltages 
than this circuit will produce. 

All the transijitors specified are common types and 
inexpensive and the total cost of the semiconductors 
is unlikely to be more than about £1-50 including the 
output pair. 

The circuit is very largely based on one published 
by Mullard's and no originality is claimed. There are 
however certain differences incorporated for various 
reasons. 

The switching necessary in a tape recorder circuit 
tends to make the understanding of the circuit 
difficult and so Pig. 1 shows the effective circuit on 
playback. Fig. 2 shows it in on record. The component 
numbers are shown and if the values given in the 
main circuit are used these will work perfectly well 
by themselves without switching if for instance only 
a tape playback amplifier is needed. 

PLAYBACK 

From Fig. 1 il will be seen that Trl and Tr2 are 
coupled as a pretty conventional preamplifier to 
boost the signal from the tape head. R7, the emitter 
resistor of Tr2, is not decoupled, this provides a 
measure of feedback to the whole stage as the bias 



Transistor 

TAPE RECORDER «««« 






In January we published full details for a stereo tape 
recorder and at the time we promised an article de- 
scribing a mono version. The amplifier described here 
can be used with any type of tape deck, though the 
tape heads specified must be used. 

THE design of a transistor tape recorder has 
its own special problems. High gain is 
necessary since the output from a tape head 
on playback is very low but at the other end, in the 
circuits feeding the loudspeaker, high currents are 
passed and it is vital to ensure that earth loops 
do not create instability. Readers who wish to build 
this circuit should not deviate from the general 
layout unless they are absolutely certain that they 
know exactly what they are doing. 

The problems of earth loops are not helped by the 
necessity for including fairly complex switching to 
alter the function of the amplifier from record to 
playback. An early prototype of this project was 
violently unstable due to the voltage drop in only a 
2in. length of wire; this may give some indication of 
how important careful layout is. 

Care has also to be taken in another field. Modern 
transistors of the type used here have frequency 
responses reaching to several Megahertz and a 

698 



to Trl is taken from the emitter of Tr2 via R5. This 
feedback improves the stability of the amplifier. C3, 
a low value capacitor, has little effect at audio 
frequencies but effectively cuts out the r.f. signals, 
which may have been picked up, from later stages. 
Tone control is achieved by coupling feedback from 
Tr2 collector to Trl emitter via C6 and VR2 To 




Fig. 1 : The effective circuit on playback. 



ensure quiet and stable operation, the supply to Trl 
collector must be adequately decoupled, this being 
achieved through R6 and C2. 

After the volume control, the output is fed to a 
fairly conventional transformerless complementary 
pair output stage. It is d.c. coupled throughout with a 
variety of feedback and stability circuits. Conven- 
tional connections would take the junction of 
C10-R15 to the junction of R24 and R25 instead of 
the base of Tr6; the reason for deviating from this 
will become apparent from the record stage. 

TH1, a VA1077 32il thermistor, holds the bases of 
the output pair close together, as far as potential is 
concerned, while the trimmer VR3 linearises the 
operation and sets the output current. RIO applies a 
degree of negative feedback to the first part of the 
output stage. 

RECORD 

On record the input to Trl is connected to the 
input sockets, the first of which is unattenuated, the 
second which is severely attenuated for inputs of up 
to 2V. The input impedance of both is fairly high, 

about lOOkft. 

The preamplifier and the first two stages of the 
main amplifier operate identically except that the 
tone control is disconnected and the volume control 
becomes the record level control. TH1 and VR3 are 
included but in fact their low value means that they 
can be ignored in the record position; R16 goes 
directly to chassis and acts as the collector load. 
Output to the tape head is taken from the collector 
of Tr4 (effective) via Cll, CI 2 and R21. The VU 
meter is connected via R22, the actual value of which 
should be selected later. 

In the record mode, transistors Tr5 and Tr6 are 
coupled as an oscillator with the erase head, the 
potential divider chain R17, R18, R19 and R20 pro- 
viding the correct bias voltages. This arrangement 




Fig. 2 : The effective circuit on record. 

gives a high voltage swing across the erase head. The 
a.c. bias necessary for correct operation is applied to 
the record head via C16. 

SWITCHING 

To alter the function of the amplifier from record 
to playback an eight-pole, two-way switch is needed. 
The various functions can be studied in the complete 
circuit diagram shown in Fig. 3. The VU meter is 
only operational on record and serves as a level 
indicator. 

The type of switch used is not important but may 
be hard to obtain. That used in the prototype is made 
up from "Make-a-Switch" parts with two six-pole. 
two-way wafers. 



EQUALISATION 



For the best signal-to-noise ratio, on record, treble 
boost should be applied to the signal and on playback, 
bass boost should be applied. In fact these tend to be 
self-cancelling if a slightly worse signal-to-noise ratio 
can be accepted (and it is only very slight with 



J&r 




^h^® 



CE :£> 



Fig. 3 : The complete circuit. SW1 is shown in the record position. The connections for Tr5 and Tr6 are shown in Fig. 6. 




699 



modern tape). The author has a number of pro- 
fessionally recorded tapes and recordings, made with- 
out equalisation using this amplifier, were hardly 
different from these. On playback the tone control 
gives a wide control over the frequency response and 
this compensates somewhat for the lack of equalisa- 
tion. 

HEAD SWITCHING 

The tape heads specified are both four-track and it 
is of course necessary to switch from one to the 
other. This is simply accomplished by fitting a slide 
switch near the heads, the siting will depend on the 

ir components list 



9" 



Resistors 

R1 10MQ -!W 
100k.Q 
56U 
lOOkQ 
330kQ 
18kfi 
tkfi 
12M! 
10k.Q 

All AW, 



R2 
R3 

m 

R5 
R6 
R7 
R8 

R9 



R10 
R11 
R12 
R13 
R14 
R!5 
R16 
R17 
R18 
3% exce 



mi 

1 50k< J 

4im 

39kO 
390Q 
2-2KQ 

seoa i 



■w 



R19 
R20 
R21 
R22 
R23 
R24 
R25 



' ated 



■n-: 



12k£> 

im 
taiw 

1Q1W 



VR1 10kU log. pot with douche pole switch 

VR2 50kil Sin. pot 

VR3 50Q (47fi) skeleton preset 



Capacitors 

C1 3-2/tF 25V 
10/*F 25V 
200pF 
100/tF 25 V 
3-2/iF 
8-8nF 
(6,800pF) 



C2 
C3 
C4 
C5 
C6 



C7 



C11 



3 2 H F 25V 



(3,0OOpF) 
10/xF 25V 



C13 O-OS^F 



C17 160/xF 25V 



C12 0-47mF 



Semiconductors 

Tr1 BC169C 

Tr2 BC169C 

'Tr3 BC169C 



Tr4 AC128 
Tr5 AD161 



Tr5 AD161 \ , . . 
Tr8 AD162 } matchG <i pair 



liscel Ian ecus 

TH1, VA107732i2 thermistor; L.S., 15Q loudsp 
SW1— see text; Veroboard-see text; DIN 
-ts (2 off) and extension IS. socket; VU 
Aluminium chassis— see text. 



Verc board 



Tr5 

8° 

Tr6 



Tag strip 



Site holes to Sift '(see lext) 



Bend 90^. 



1; VUM Tone 



Volume SWt 



f-©---$=^dk- -^ - & 





Fig. 4: Details of the metalwork. 



deck used. Alternatively, this switch could be 
incorporated on the main chassis. 

CONSTRUCTION 

A very simple chassis arrangement is used for the 
amplifier, the dimensions are shown in Fig. 4. The 
input sockets and loudspeaker socket are at one end 
with the VU meter at the other; the function switch, 
the volume control and the tone control he in 
between. The majority of the components are 
mounted on a piece of Veroboard 5in.X2 1 2 in. (a 
standard size). Four holes are drilled in this for later 
mounting to the chassis. 

The power transistors, AD161 and AD162, need to 
be heat-sunk and these are fitted at one end of the 
Veroboard near the switch. A small tag-strip holds 
the large capacitor C17 and acts as an anchoring 
point for the output pair emitter resistors, R24 and 
R25. Rl and R2 are mounted directly on the input 
sockets. 

Building the Veroboard panel should be straight- 
forward, the layou: is shown in Fig. 5. The necessary 
connections to the board are made with Veropins at 



1 2 3 <, 5 6 7 8 9 W 11 12 13 V. 15 16 17 18 19 20 21 22 23 2A 25 26 27 2fl 79 *> n 32 33 



From VR1 



To SW1 



To SW1 



To VR1 



To VUM 



+ 22V 
To 5c 



ToSWI 



To eras* head 
ToSWI 




Mounting holes 



Break in veroboard 
Fig. 5: The main component layout on Veroboard. 



700 



BRAND NEW 
GUARANTEED 



SEMICONDUCTORS & COMPONENTS 

SOLE AGENTS FOR SOLID STATES DEVICES INC.. (USA). IN U.K. 



RETURN OF POST 
SERVICE 



TRANSISTORS 



2G301 
2G302 
2Q303 
20 306 
2G308 
2G309 
2G371 
2Q374 
2G381 
2N404 
2X696 
2X697 
2X698 
2X706 



BOp 

20p 

sop 

42)p 
SOp 
30p 
15p 

sop 

22!p 
224P 
20p 
17p 
2Sp 
12JP 



2X705A 124P 
2X708 16p 



2X709 
2X718 
2N726 
2X727 
2X914 
2X916 
2X918 
2N929 
2N930 



624p 
25p 
SOp 
SOp 
17iP 
174P 
SOp 
224P 
274p 



1!? 

lOp 

*i p 

lOp 
09p 
Up 
07p 
09p 
09p 
12p 



2X1090 224P 
2X1091 224p 
2X1131 25p 
2X1132 25p 
2N1302 171P 
2N1303 17iP 
2X1304 22*P 
2X1305 224P 
2N1306 
2X1307 
2X1308 
2X1309 
2N1507 
2N1813 
2N1831 
2N1632 
2X1638 274P 
2X1639 274P 
2X1671B£100 
2N1711 25p 
2X1889 82Jp 
2X1893 37Jp 
2X2147 824P 
2X2148 57iP 
2X2160 571P 
2X2193 40p 
2X2193A 424P 
2N2194A SOp 
2X2217 274P 
2X2218 
2X2219 
2X2220 
2X2221 
2X2222 
2X2270 474P 
2X2297 SOp 
2X2368 174P 
2X2369 17jp 
2X2369A 174P 
2X2410 424P 
2X2483 27JP 
2X2484 824P 
2X2539 22Jp 
2X2S40 22Jp 
2X2613 86p 
2X2614 80p 
2X2646 52Jp 
2X2696 324P 
2X2711 B6p 
2X2712 



25p 
25p 
SOp 
SOp 
174P 
25p 
S6p 
30p 



23p 
23p 
25p 
25p 
SOp 



lop 
15p 

IS? 

Urn 



2X2713 274P 
2X2714 SOp 
2X2865 624P 
2X2904 SOp 
2X2904A 324p 
2X2905 374P 
2X2905A 40p 
2X2906 25p 
2X2906A 274p 
2 N 291)7 30p 
2X2923 
2X2924 
2X2925 
2X2926 
Green 

Yellow IBip 
Orange 124p 
2X3011 SOp 
2X3014 S2Jp 
2X3053 
2X3054 
2X3055 
2X3133 
2X3134 
2X3135 
2X3138 
2X3390 
2X3391 
2X3391A 30p 
2X3392 17 1 p 
2X3303 15p 
2X3394 15p 
2X3402 22JP 
2X3403 224P 
Post & 



2X3404 321 p 
2X3405 45p 
2X3414 22|p 
2X3415 224P 
2X3416 874P 
2X3417 374p 
2X3570 £1-26 
2X3672 97jp 
2X3605 27 U 
2X3606 274P 
2X3607 
2X3702 
2X3703 
2X3704 
2X3705 
2X3706 
2X3707 
2X3708 
2X3709 
2X3710 
2N3711 

2X3715 £1-26 
2X3716 £1.30 
2X3791 £2.08 
2X3819 S5p 
2X3823 974P 
2N3864 874P 
2X3854A 274P 
2X3S55 274P 
2X3855A SOp 
2X3856 SOp 
2X3856A 35p 
2X3858 25p 
2X3858A SOp 
2X3859 274P 
2X3859 A 324p 
2X3860 30p 
2X3866 £1.50 
2X3877 40p 
2X3877A 40p 
2X3900 874P 
2X3900 A 40p 
2X3901 97Jp 
2X3903 38p 
2X3904 35? 
2X3905 87JP 
2X3906 87JP 
2X4058 17Jp 
2X4059 lOp 
2X4000 12Jp 
2X4061 12 P 
2X4062 12 p 
2X4244 47 p 
2X4285 17 p 
2X4286 17 P 
2X4287 17 p 
2X4288 17 P 
2S4289 17 P 
2X4290 17 p 
2X4291 17 p 
2X4292 12 p 
2X4303 47 P 
2X5027 62 P 
2X5028 67 P 
2X5029 47JP 
2X6030 424P 
2X5172 12tP 
2X5174 524P 
2X5175 524P 
2X5176 46p 
2X5232A 80p 
2X5245 45p 
2X5246 424P 
2X6249 674P 
2X5288 £3-25 
2X62B6 £2-75 
2X5267 £2-624 
2X5305 37Jp 
2X5306 40p 
2X5307 874P 
2X5308 874p 
2X5309 821p 
2X5310 424P 
2X5354 27Jp 
2X6356 274p 
2X5356 821p 
2X6365 474P 
2X6366 824P 
2X5367 674P 
2X5457 87JP 
28000 



40310 

40311 

40312 

40314 

40320 

40323 

40324 

40326 

40329 

40344 

40347 

40348 

40360 

40361 

40362 

40370 

40406 

40407 

40408 

40410 

40467A 

40468A 

40600 

AC 107 

AC126 

AC127 

AC128 

AC154 

AC176 

AC187 

AC188 

ACY17 

ACY18 

ACY19 

ACY20 

ACY21 

ACY22 

ACY28 

ACY40 

ACY41 

ACY44 

AD140 

AD149 

AD150 

AD161 

AD162 

AF106 

AP114 

AF115 

AF116 

AF117 

AF118 

AF119 

AF124 

AF125 

AF126 

AF127 

AF139 

AF178 

AF179 

AF180 

AF18V 

AF239 

AF279 

AF280 

AF211 

A3Y26 

ASY27 

ASY28 

A8Y29 

ASY36 

A8Y50 

A8Y61 

A3Y54 

A3Y86 



ISp 
27Jp 
30p 
SOp 
25p 
30p 
40p 

eop 

50p 
16p 
16p 
32tP 
224P 
224P 
97tp 
20p 
25p 
17JP 
27 J P 
42JP 



821P 
SOp 
75p 
85p 



45p BC212L 

85p BCY30 

47JP BCY31 

874P BCYSa 

47Jp BCY33 

32jp BCY34 

47ip BCY38 

871P BCY39 

30p BCY40 

874P BCY42 

674P BCY43 

52iP BCY54 

42ip BCY58 

47»p BCY59 

674P BCY60 

32IP BCY70 

57|p BCY71 

40p BCY72 

521p BCZ10 

624P BCZ11 

57'p BD116 £1-121 

85p BD121 66p 

57Jp BD123 

30p BD124 

20p BD131 

25 p BD1S2 

20p BDY10 £1-874 

22Jp BDY11 £1-621 

25p BDY17 £1-50 

624P BDY18 £1-76 

374P BDY19 £1-971 

27tp BDY20 £1-124 

25p BDY38 97(p 

25p BDY60 £1-25 

25 p BDY61 £1-25 

25p BDY62 £1-00 

20p BF115 

20p BF117 

20p BF163 

26p BF167 

40p BF173 

62JP BF177 

67Jp BF178 

62»P BF179 

87Jp BF180 

87Jp BF181 

42(p BF184 

25p BF185 

86p BF194 

26p BF195 

25p BF196 

62ip BF197 

20p BF198 

22Jp BF200 

20p BF224 

20p BF225 

17Jp BF237 

87|p BF238 

42)p BF244 

724P BFW61 471 p 

624P BFX12 " 

424P BFX13 

42!p BFX29 

47Jp BFX30 

62ip BFX42 

824P BFX44 

25p BFX68 

37Jp BFX84 

27{p BFX85 

274P BFX88 

25p BFXS7 

26p BFX88 

324p BFX89 , 

25p BFX93A 70p 

82|p BFY10 S2tP 



B8X28 
B8X60 
BSXfll 
BSX76 
B8X77 
B8X78 
B8Y10 
B8Y11 
B8Y24 
B8Y25 
B8Y26 
BSY27 
B8Y28 
B8Y29 
BSY32 
B8Y36 
B8Y37 
BSY38 
BSY.19 
B8Y40 
B8Y51 
B8Y52 
B8Y53 
B8Y54 
B3Y56 
B8Y78 
B8Y79 
BSY82 
B8Y90 



32!P 

824p 

62! P 

22)P 

271p 

274P 

27JP 

274P 

15p 

15p 

17iP 

17JP 

17JP 

174P 

25p 

25p 

25p 

224P 

224P 

324P 

32,-P 

324P 

374P 

40p 

SOP 

47iP 

45P 

52JP 

574P 



B8Y9SA 121P 
BSW41 421P 
B8W70 
C1U 



25p 

47Jp 

871P 

18p 

19p 

SOp 

SOp 

SOp 

S5p 

32ip 

2SP 

42|P 

17iP 

15p 

421P 

421P 

42JP 

52tP 

14p 

18p 

23p 



221P 
224P 

SOp 

SOp 
371P 
37ip 
87Jp 

26p 
82»p 

26p 
27»p 

25p 
62SP 



274P 
75p 

271P 
55P 
40p 

371P 
SOP 

37JP 
40p 

37SP 
40P 
30p 
20P 
20P 
20P 
20p 



XKT281 271p 
XKT401 87»p 
XKT402 90p 
XKT403 75p 
XKT404 82iP 
XKT405 75p 
XKT406 62iP 
XKT451 62 Jp 
XKT452 82iP 
XKT453 47Jp 
XKT603K82JP 
XKT813F321p 
XKT'>74F SOp 
XKT677F SOp 
XKT713 25p 
XKT781 SOp 
XKT10419 30P 
XKT10439 

371P 
NKT10519 

32ip 
XKT20329 

47Jp 
XKT20339 

37IP 
XKT80111 

771P 
XKT80112 

97}p 
XKT80113 

£1.12 
XKT80211 

92iP 
XKT80212 

92tp 
XKT80213 

B25P 
XKT80214 

92lp 
XKT80215 

92JP 
XKT80216 

Mis 



AU103 £1-25 BFY11 

ASZ21 42JP BFY17 

10p BFY18 

lOp BFY19 



42iP 
22 iP 
32ip 
32! P 



lOp BFY20 £1-60 



18p 
46p 
62p 
SOp 
30p 
25p 
25p 
25p 
20p 



2S020 

28102 

28103 

28104 

28501 

28602 

28503 

3X83 

3X128 

3X140 

3X141 

3X142 

3X143 

3X162 

R.C.A. 

40060 

40251 

40309 



76p 
£200 
50p 
25p 
2Sp 
32ip 
85p 
27iP 
40p 
70p 
77Jp 
72»p 
55p 
871p 
87Jp 
52iP 
55p 
32iP 
32iP 



15p BFY21 

16p BFY24 

16p BFY25 

10p BFY26 

20p BFY29 

20p BFY30 

20p BFY41 

20 p BFY43 

87tP BFY50 

lOp BFY51 

lOp BFY52 

12p BFY53 



42»p 
45p 
25p 
20p 
SOp 
SOp 
SOp 

62jp 
23p 
2flp 
23p 

17|p 



17tP BFY56A 57Jp 



20p 



Packing 124/p p 

Matching chai 

Prices si 



BC107 

BC108 

BC109 

BC113 

BC115 

BC116A 

BC118 

B0121 

BC122 

BC125 

BC126 

BC140 

BC147 

BC148 

BC149 

BC152 

BC157 

BC158 

BC159 

BC160 

BC167 

BC168B 

BC16SC 

BC169B 

BC169C 

BC170 

BC171 

BC172 

BC175 

BC182 

BC183 

BC184 
;r order. Europe 2Sp. Commc 

Ee (audio transistors only) I2jp 
ject to alteration without prii 



30p 
42 1 P 
571P 
67)p 
27 {p 
25p 
25p 



, BFY7 

lip BFY76 

12p BFY77 

62ip BFY90 

lip BFW58 

lOp BFW59 

lip BFW60 

lip BPX25 £1-85 

12p BPX29 £1-80 

12jp BPY10 £1-45 

ISp BRY39 

16p B8X19 

22|p BSX20 

10p B8X21 

09p BSX26 

lip B8X27 



47JP 
17»p 
17jp 
37iP 
45p 
471P 



C424 
C425 
C426 
C428 
C744 
D16P1 
D16P2 
D16P3 
D16P4 
OET102 
GET113 
GET114 
GET118 
(!F.T119 
OET120 62iP 
GET873 12VP 
(1ETB80 30P 
GET887 20P 
GET889 22iP 
GET890 22iP 
GET896 22 (P 
GET897 221P 
(;ET898 22|P 
MJ400 £l-07i 
MJ420 £1-18! 
MJ421 £1.12k 
MJ430 £1-024 
MJ440 85P 
MJ480 97!P 
MJ481 £1-25 
MJ490 £1-00 
M.I491 £1-374 
MJ1800 £2-174 
MJE340 624P 
MJF.520 60P 
MJE521 73P 
MPF102 424P 
MPF103 374P 
MPF104 374P 
MPF105 374P 
MP33638 324P OC200 
XKT0013 474P OC201 
XKT124 424P 
XKT125 274P 
XKT126 274P 
XKT123 274P 
XKT135 274P 
XKT137 824P 
NKTJ10 30P 
XKT211 80P 
XKT212 30p 
NKT213 80P 
XKT214 224P 
XKT215 224P 
XKT216 374P 
XKT217 424P 
XKT219 80P 
XKT223 27 4P 
XKT224 25 P 
XKT225 224P 
XKT229 SOP 
XKT2S7 35P 
XKT238 25P TI853 
NKT240 274P TI860 
XKT241 274P 
XKT242 20P 
XKT243 624P 
XKT244 174P 
NKTJ45 20P 
20p 
30P 
20p 
20p 

SOp 

20p 

20p 
n wealth(Air)65p(MIN.) 
extra per pair. 



TTL. LOGIC I.C. NEW PRICES 



OC20 

OC22 

OC23 

OC24 

OC25 

OC26 

OC28 

OC29 

OC35 

OC36 

OC41 

OC42 

OC44 

OC45 

OC49 

OC70 

OC71 

OC72 

OC74 

OC75 

OC78 

OC77 

OC81 

OC81D 

OC8S 

OC84 

OCI39 

OC140 

OC170 

ocr 



OO20-J 
OC203 
OC204 
Ot-205 
OC207 
OCP71 
ORP12 
OBP61 
P346A 
T18S4 
TI843 
TI844 
T1846 
TI846 
TI847 
T1848 
T1849 
TI850 
TI851 
TI852 



XKT261 
XKT262 
XKT264 
XKT271 
XKT272 
XKT274 
XKT275 



TI881 

TIS82 

TIP29A 

TIP30A 

TIP31A 

TIP32A 

TIP33A 

£1 02 !p 
TIP34A £205 



75p 

SOp 
60p 
BOp 
SOp 
274P 
821 p 
62 -!p 
SOp 
62jp 
22!P 
25p 
20p 
124P 
15p 
15p 
124P 
124P 
32 4P 
224P 
22»P 
30p 
20p 
22-p 
25p 
2Sp 
324P 
324P 
30p 
SOp 
40p 
60p 
76p 
42-? 
424P 
90p 
75p 
424P 
824P 
SOp 
224P 
624P 
27p 
lOp 
lOp 
Up 
Up 
12$p 
124P 
174P 
124P 
124P 
224P 
224P 
25p 
274P 
50p 
80p 
62Vp 
75p 



8X7400 
8X7401 
8X7402 
8X7403 
8X7405 
SX740K 
8X7407 
8X7408 
SX7409 
8X7410 
SX7411 
8X7412 
BX7413 
8X7420 
8X7423 
8X7427 
8X7428 
8X7430 
SX7432 



1-11 12-24 

£p £p 

020 018 

020 018 

020 0-18 

20 018 

0-20 0-18 

080 075 

020 018 

020 018 

020 0-18 

020 018 

028 021 

048 048 

040 0-38 

020 018 

051 047 

0-48 0-45 

0-80 075 

023 015 

048 042 



BH7488 

8X7437 
ssti:;s 
8X7440 
8X7441 
8X7442 
8X7443 
8X7444 
8X7445 
8X7440 
SX7447 
8X7448 
8X7449 
8X7450 
8X7451 
3X7453 
8X7464 
8X7460 
8X7470 



1-11 12-24 

£p £p 

080 075 

064 006 

064 060 

028 021 

AX 87 0-88 

0-85 0-81 

2-86 270 

288 270 

2-50 240 

100 095 

100 095 

100 095 

100 (r85 

0-20 018 

020 018 

0-20 018 

020 018 

020 018 

040 038 



1-11 12-24 
£p £P 



8X7472 

8X7473 

8X7474 

3X7475 

8X7476 

8X7480 

8X7481 

S N74-S2 

8X7483 

8X7484 

8X7485 

SS7-ISC. 

3X7490 

8X7491AX 1-21 

HX7492 0-87 



0-32 
043 
043 
045 
045 
0-70 
1-40 
087 



080 

041 
041 
044 
0-44 
065 
138 
082 



8X7493 
8X74B4 
3X7495 
SX749B 



087 0-82 

200 1-85 

362 340 

033 030 

087 084 

110 

084 

084 

084 

0-84 

0-84 



087 
0-87 
0-87 
0-87 



MULLARD SUB-MI N ELECTROLYTIC 

C425 ranne »xial lead 6p each 

Values: (uF/V): 0-84/64: 1/40: 1-6/25; 2-5/16; 2-5/64; 4/10; 4/40; ;/84; 
6-4/6-4; 6-4/25: 8/40; 10/16; 10/64; 12-5/25; 16/40: 20/16; 20/64: 25/6-4; 
25/25: 32/10: 32/40; 32/64; 40/16; 60/6-4; 50/25; 50/40; 84/10; 80/2-5; 
80/10: 30/25; 100/6-4; 125/10; 126/16; 200/6-4; 200/10; 320/6-4. 



SILICON RECTIFIERS 



400 
16p 
22!P 
SOp 
65p 
— 574P 824P 774P 



SO 100 200 

lOp 124P ISp 

Up — — 

— — 25p 

524 P 674 P 



1000 1200 
20p — 



600 800 

174P 19p 

— 80p 

324P 85p — — 

774P 884P 974P £1-25 



80p 90p £100 



1 amp ami 3 amp are plastic encapsulation. 



90p 
£1-25 



974P £1-20 £1-574 
£1-50 £250 — 



DIODES & RECTIFIERS 



1X34 A 

1X914 

1X916 

1X4007 

1344 

18113 

18120 

18121 

18130 

IS131 

IS132 

13920 

1S922 

1S923 

IS940 



lOp 

074P 

074P 

22iP 

lOp 

ISp 

ISp 

17 4p 

124P 

12iP 

16p 

074P 

074P 

074P 

074P 



lOp 
lOp 
lOp 



AA119 
AA129 
AAZ13 

AA7.15 124P 

AAZ17 124P 

BA100 15p 

BAV02 224P 

BA110 324P 

BA114 221P 

BAU5 074P 

BA141 32 tP 

BA142 32ip 

BA144 12iP 

BA145 SOp 

BA154 12-P 

BAX13 184P 



BAX16 124P 

BAY18 174P 

BAY31 074P 

BAY38 25p 

BY100 17 4P 
BY103 
BY12 
BY124 
BY126 
BY127 

BYI64 . 

BYX10 224P 

BYZ10 35p 

BYZ11 324 P 

BYZ12 SOp 



BYZ13 25p 
F8T3/4 224P 
OA5 174P 



22JP 

474 P 

ISp 

ISp 

174P 

674P 



OA10 

OA9 

OA47 

OA70 

OA73 

OA79 

OA81 

OA85 

OA90 

OA91 

OA95 



224P 

lOp 

074P 

074P 

lOp 

OSp 

074P 

074P 

071P 

07»p 

074P 



OA200 10p 
OA202 10p 



TRIACS 



SC35D 
8C36D 
8C40D 
8C41D 
SC45D 
8C46D 
SC50D 



£1124 

£100 

£1-50 

£120 

£1-624 

£1-424 

£2 05 



8C51D £195 
40430 974P 



40486 
40528 



95p 
721P 



40430 £1-30 
40432 £1874 
40512 £1-45 



BRIDGE RECTIFIERS 



A. PIV 

1 100 
1.4140 

2 50 
2 200 
2 400 



47 |p 
52IP 
55p 
70p 
80p 



60p 
70p 
OSp 
624P 
874P 
£1124 



THYRISTORS (SCR) 

PIV 60 100 200 300 400 
1A 2Sp 274P 87 Jp 40p 47|p 
4A 47JP 55p 57Jp — 77JP 
5A — 55p 65p — 90p 
7A — 55p 85p — 97lP 
TIC47 O.Ranip. 200 PIV 55p. 
Also 12 amp. 100 PIV 75p 
2X3525 at £1.121p 
VEROBOARD 



0-1S 



"•I 



nocic 



Matrix Matrix 
2 J x 31 in 17 Jp 20p 

2J X 6 In 21p 24p 

3| x 3Jln 21p 24p 

31 x Sin 274P 87Jp 

5 x 17in (Plain) 85p — 

Veto Pins (Bag of 36) 20p 
Vero Cntter 45p 

Pin Innertion Tools (-1 and -15 
mat rix) at 56p. 

HEAT SINKS 

4-8 X 4 x lin Finned for Two 
TO-3 Trans.. 474P- 4-8 x 2 x lin 
Finned, for One TO-3 Trans.. 
82JP- For SO-1. 24p- For TO-5. 
5p Finned. For TO-18, 5p 
Finned. For TO-18, 1/- Finned. 



RESISTORS 

Carbon Film 
4 watt 6%, lp- 
} watt 5%, 14P- 
i watt 6%. 8p- 
1 w 2% M/O 4p. 

1 watt 10°,i. 24P- JW & jJW 

2 watt 10%, 6p. 



4%V, 1W & 2W 
E24 Series. 



E12 Series. 



MULLARD C280 M/FOIL 
CAPACITORS 

0-01, 0-022. 0033, 0047 8p each 
0-068. 0-10 . - 4p each 

0.15, 0-22. 0-33 . . . - 5p each 

0-47 8p 

0-68 UP 

1/iF MP 

1-ouF 81p 

2-2^iF 26p 

WIHE-WOnSD RESISTORS 

2-5 watt 6% (up to 270 ohms 

only). 7JP 
5 watts 5% (up to 8 -2k£J only). lOp 
10 watt 8% (up to 25kQ only), 

124P , 

POTENTIOMETERS 

Carbon: 

Log. and Lin., less switch. 18p. 
Log. and Lin., with switch, 25p. 
Wire-wound Pots <3W), 88p. 
Twin Ganged Stereo Pots, Log. 
and Lin., 40p. 

PRESETS (CARBON) 
01 Watt 6p VERTICAL 
0-2 Watt 6p OR 

0-3 Watt 74P HORIZONTAL 

THERMISTORS 

R53 (8TC) £1-274 VA3705 874P 
K151 (Ik) 1B4P VA1077 20p 
Mullard Thermistors also In 
stock. Please enquire. 



Tel. 01-452 0161/2/3 
Telex 21492 



-T : „ r/s. Send 5p for new Comprehensive Semi- CALLERS WELCOME 

A. MARSHALL & 50IM conductor and I.C. list (24 pages). HRS. 9-5.30 KOX.-FBI. 

28 CRICKLEWOOD BROADWAY, LONDON, N.W.2 US t^bs. 



701 




The Veroboard panel— compare this with Fig. 5. 

both ends of the board and much work will be saved 
later if these are fitted at the same time as the main 
components and soldered in. 

There are a number of breaks in the copper con- 
ducting strip and these are shown clearly on the 
diagram. 

There is a reasonable amount of room on the board 
but care should be taken to ensure that extra large 
components are not selected. The » 8 W resistors 
specified will fit neatly as shown. The skeleton preset 
VR3 will also fit neatly into 15in. matrix Veroboard 
it fitted at an angle as shown. 

Naturally the output transistors have to be 

Power supply — ve 



insulated from the chassis and this applies to Tr6 as 
well, even though the collector is at chassis potential. 
It is this sort of thing that can cause earth loop 
problems. 

One connection on the small tag strip is the 
common earthing point and all wires which carry any 
appreciable current are earthed directly to this. A 
second earthing point is on the input DIN sockets but 
as these wires are taking no current to speak of, no 
problem arises. Vvfhen finally connected to the tape 
deck, be sure that the metal body of the deck is 
connected to the main earthing point of the 
amplifier. Certain wires need to be screened, these 
are indicated on the diagrams. 

The switch wiring is shown in Fig. 7. A logical 
sequency in wiring this up is essential. It is easier to 
mount the completed Veroboard panel and the other 
components to the chassis and then proceed with the 
wiring. A heavy gauge piece of copper wire can be 
mounted alongside the switch to act as an earth bus 
bar, this being connected to the common earth point. 
If the tape deck used has incorporated switch wafers 
these could be used but this entails a lot of additional 
wire and could result in instability. 




Fig. 6: The wiring 
around the tag strip 
and the output tran- 
sistors. 

ToSW1 




R19/R20 
(129) 

Tr6b 

R16/VR3 
(H29) 



C17+ve R24/R2S R23(N29) 




C17-ve 



c, , Rear wafer _ 

Front Rear «. 

Fig. 7: The record playback switch wiring. 



TrAc(F29) 



702 



The power supply should be built separately and 
fixed some distance both from the main amplifier 
and the tape heads to avoid hum induction. The 
circuit for a suitable power supply is shown in Fig 8 

There are only two items that need to be set up 
One is VR3; for this a meter should be inserted in 
the emitter leads of one of the output pair and the 
quiescent current .should be adjusted, using VR3 to 
read about 20mA. The value of the resistor feeding 
the VU meter has to be found by trial and error. In 
use the correct recording level can be found simply 
by listening for high level distortion caused by over 
modulation of the tape. When the correct level has 
been found, the resistor R22 should he selected to 
read zero level on peaks. ■ 



Build yourself aTRANSISTQR RADIO 



NEW! ROAMER 10 WITH VHF INCLUDING AIRCRAFT 



• • • • 



10 TRANSISTORS. 9 TUNABLE WAVEBANDS, MW1 , 
MW2, LW, SW1, SW2, SW3, TRAWLER, BAND, VHF 
AND AIRCRAFT BAND 

Built in Ferrite Rod Aerial for MW/LW. Retractable, chrome plated 7 section Telescopic 
Aerial can be angled and rotated lor peak short wave and VHP listening. Push Pull 
•output using 600niw Transistors. Car Aerial and Tape Record Sockets. Switched Ear- 
Dicoc Socket complete with Earpiece. 10 Transistors plus 3 Dlodns. 7in X 4in Speaker. 
Air Spaced ganged Tuning Condenser with VHF section. Volumu on,ofl. Wave Change 
and Tone Control. Attractive Case in black with silver blocking. Size 9* X - X 4. 
Easy to follow instructions and diagrams. Parts price list and easy build plans 30p 
(FREE with parts). 



Total building cost 

£8-50 

P. F. 4 Ins. BOp 
(Overseas P. * P. £1) 



- -.•:." l 'W«i!ii!l 



S»^»^»^^^^«g^^^»^^^" 



ROAMER 

EIGHT 

Mkl 




NOW WITH 
SWITCHED TONE 
CONTROL 

7 Tunable Wavebands: MW1, MW2. LW, BW1, 8W2, 
8W3 and Trawler Band. Built in Ferrite Rod Aerial 
for MW and LW. Retractable chrome plated Tele- 
scopic aerial for Short Waves. Push pull output using 
600mW transistors. Car aerial and Tape record socket*. 
Selectivity switch. Switched earpiece socket complete 
with earpiece. 8 transistors plus 3 diodes. 71n. X 4in. 
Speaker. Air spaced ganged tuning condenser. Volume/ 
on/otl, tuning, wave change and tone controls. 
Attractive case in rich chestnut shade with gold 
blocking. Size 9 X 7 X 4in. approx. Easy to follow 
instructions and diagrams. Parts Price List and Easy 
Build Plans 85p (FREE with parts). 

Total building cost X?C-QD 

(Overseas P. * P. £1) ft« %»» 



ROAME 

SEVEN 

MKIV 




,„~~ «...«»..»—»»»»»"»»»»»» 



POCKET 
FIVE 




7 Tunable Wave- 
bands: MW1, MW2, 
LW, 8W1, 8W2, 
8W3 and Trawler 

Band. Extra Medium waveband provides easier tuning 
of Radio Luxembourg, etc. Built in ferrite rod aerial 
for MW and LW. Retractable 4 section 24in. chrome 
plated telescopic aerial for SW. Socket for Car Aerial. 
Powerful push-pull output. 7 translators and 2 diodes, 
Including Micro-Alloy R.F. Transistors. 7 x 4in. P.M. 
speaker. Air spaced ganged tuning condenser. Volume/ 
on/off, tuning and wave change controls. Attractive 
cane with carrying handle. Size 9 X 7 X 4in. approx. 
Easy to follow instructions and diagrams. Parts price 
list and easy build plans lfip (FREE with parts). 
Earpiece with plug and switched socket tor private 
listening, SOp extra. 

Total building costs £5*98 P p ' * 



ROAMEI 
SIX 



(Overseas P. A P. £1) 



I Ins. 41p. 



3 Tunable Wavebands: 

MW. LW, Trawler Band 

with extended M.W. 

band for easier tuning 

of Luxembourg, etc. 

7 stages — B transistors and 2 diodes, 

supersensitive ferrite rod aerial, fine 

tone moving coil speaker. Attractive black and gold 

case. Sixe Si x It x 3tin. Easy build plans and 

parts price list lOp (FREE witn parts). Earpiece with 

plug and switched socket tor private listening SOp 

extra. 

P.P. 4 

Ins. 21p 



Total building costs X?0«0 X 

(Overseas P. 4 P. 63p) dt#«5i afaU 




TRANSONA 1 
FIVE I 

NOW WITH <j 
3in SPEAKER 



3 Tunable Wavebands: MW, LW and Trawler Band. 
7 stage-^S transistors and 2 diodes, ferrite rod aerial, 
tuning condenser volume control, fine tone 31n. 
moving coil speaker. Attractive case with red speaker 
grille. 8ize 61 X 4t X liln. Easy build plans and 
part* price list lOp (FREE with parts). Earpiece with 
plug and switched socket for private listening 30p extra. 

Total building costs jpO-Kn P " r " * 

(Overseas P. * P. 68p) d&fc «#W Ins.22p 



6 Tunable Wave- 
bands: MW, LW, 
8W1, 8W2, Trawler 
band plus an extra 

M.W. band tor easier tuning of Luxembourg, etc. 
Sensitive ferrite rod aerial and telescopic aerial for 
Short Waves. 3in. Speaker. 8 stages— 8 transistors 
and 2 diodes including Micro-Alloy R.F. Transistors, 
etc. Attractive black case with red grille, dial and 
black knobs with polished metal inserts. Size 9 X Si 
X 2jin. approx. Easy build plans and parts price list 
15j> (FREE with parts). Earpiece with plug and 
switched socket for private listening SOp extra. 

Total building costs OJiQQi i' a 

l) dbU tfOlns.26p 



(Overseas P. 4 P. £1) 



TRANS 
EIGHT 




8 Tunable Wave- 
bands: MW. LW. 
8W1, 8W2, SW3 
and Trawler Band. 

Sensitive ferrite rod aerial for MW. and L.W. Tele- 
scopic aerial for Short Waves. 3in. 8peaker. 8 improved 
type transistors plus 3 diodes. Attractive case in 
black with red grille, dial and black knobs with polished 
metal inserts. Size 9 X 6t X 2Jin. approx. Push pull 
output. Battery cconomlscr switch for extended battery 
life. Ample powor to drive a larger speaker. Parts 
price list and easy build plans 2Bp (FREE with parts). 
Earpiece with plug and switched socket for private 
listening SOp extra. 



Total building costs jDAmAQ 

(Overseas P. 4 P. £1) *^ ^w 



P.P. A 
Ins. 31p 



NEW! "EDU KIT" 

BUILD RADIOS. AMPLIFIERS, ETC.. 
FROM EASY STAGE DIAGRAMS. FIVE 
UNITS INCLUDING MASTER UNIT TO 
CONSTRUCT. 
COMPONENTS INCLUDE: 

Tuning Condenser: 2 Volume Controls: 2 Slider 

Switches: 4"x2f Speaker: Terminal Strip: Ferrite Rod 

Aerial: 3 Plugs and Sockets: Battery Clips: 4 Tag 

Boards: Balanced Armature Unit: 10 Transistor*: 

4 Diodes: Resistors: Capacitors: Three I* Knobs. 

Units once constructed are detachable 

from Master Unit, enabling them to be 

storod for future use. Ideal for 

Schools, Educational Authorities and 

all those Interested In radio construction. 

parts including .pC'Ckf) 
Case and Plans **» *»*» 

(Overseas P. 4 P. £1> 




P. P. 4 

Ins. 31p 



Callers aid* entrance Barretts Shoe Shop 
Open 10-1, 2.30-4.30 Mon.-Fri. 9-12 Sat. 



RADIO EXCHANGE CO 



| 61 HIGH STREET, BEDFORD. Tel. 0234 62367 

J I enclose £ please send items marked 

ROAMER TEN □ 

ROAMER EIGHT Q 

TRANSONA FIVE □ 
| POCKET FIVE □ 
I Parts price list and plans for 

■ Name 

J Address 

| I W .36 



ROAMER SEVEN 


D 


TRANS EIGHT 


□ 


ROAMER SIX 


□ 


EDU-KIT 


□ 




J 

703 



SPECIAL OFFER FOR DECEMBER ONLY 

FREE PAIR OF 

STEREO HEADPHONES 

with every complete stereo system purchased 



COMPLETE STEREO SYSTEM 




AMC can now offer this superb quality system' 
at an unheard of price. 

The backbone of the system is the HL SA 70 
Stereo Amplifier. The unit is housed in a sturd 
Teak Cabinet with a black & silver facia. Powe 
output 20 watts (speech and music). Frequenc, 
Response 15-20.000 Hz. Special features include- 
Scratch Filter. Headphone Socket and facilities for 
all types of cartridges. Together with the matching 
high quality AMC 3-way speaker system, world 
renowned Garrard 2025TC deck including plinth 
cover and Sonotone 9TAHC cartridge, make an 
unbeatable system. 

Za^ls^. gggjEg VI rY^O "'* «>""»" G 8 °° *°«""'' 

TELETON CRIOT 

Stereo System 

AM/FM Stereo Tuner Amplifier in superb 
walnut cabinet 4 ,w a "» per channel, AFC. 
built-in MPXand Cer/XTAL input, com- 
plete with pair of matching Teleton 
speakers £29-95 inc. leads & plugs. P &P 
oitp. 

With matching G;.rrard 2025TC deck 
including plinth, cover and a Sonotone 

Vm t^t** £4Z °° ,nc - ,eads & #** 




It's here, the latest model in a 
beautiful walnut case. Special 
sliding balance control, scratch 
filter, and loudness control. 6x6 
watts RMS. Switched inputs for 
Xtal. aux. tape and Mag. £19-95 
inc. leads & plugs. P & P 37p. 




GARRARD SP25 Mklll 

Turntable complete with Goldring G.800 
Magnetic Cartridge, plinth & cover. 

OUR FANTASTIC 
PRICE £19-95 

nc. leads & plugs. P & P 50p. 

FANTASTIC KELETRON SPEAKER BARGAINS 




Roc/Price Our Price P & P 
KN 400 £8 05 each £5-80 75p 
KN 600 £13 43 each £9 99 85p 
KN 800 £15-90 each £10-50 £1 00 



Rec/Price Our Price P & P 
KN I 100 £20 40 each £14 001 
KN l600£25-20 each £16 00 [ £ I -50 
KN 2l00£30-60 each £20 00 



DECKS 

Goldring GL75 m 

Plinth, with Tinted Per 
with G.800 magnetic 
P & P 50p. 



nted in Teak 
:x Lid complete 
tridge. £45 00. 



Goldring GL69 mounted in Teak Plinth, 
^'^J inted Perspex Lid complete with 
G.800 magnetic cartridge. £37 00. P & P 
SOp. 

Garrard AP76 mounted in Teak Plinth, 
with Tinted Perspex Lid complete with 
Goldring G.800 magnetic cartridge. 
£30 50. P & P 50p. 



CARTRIDGES 
Goldring G850 £4-50 
Goldring G800 £7-50 
Goldring G800H £705 
Goldring G800E £11-15 



IP& P 
f I2*p 



ALL ITEMS ARE FULLY 
GUARANTEED AND COME 
BRAND NEW IN MANU- 
FACTURERS SEALED CAR- 
TONS 



DEMONSTRATIONS 
BY APPOINTMENT 



MAIL ORDERS TO: 

-AJVLCCcl 



Dept P.W., 149 Etchingham 
Park Road, London, N.3. 
Tel: 01-346 3313 
Make Cheques and Money 
Orders payable to AMC Co. 
E.O.E. Subject to availability. 




RANGER HQ RADIO MICROPHONE 

Build or buy a Professional, Transistorised 
Radio Microphone 

tV No external connections 

•k 4 Transistors Ready for use. Just switch on 

-tV Receive on any VHF radio, preferably with 

AFC, and easily coupled to P. A. etc. 
•k Excellent Rarge 
tV Internal aerial 
• Overall size 8 x 1i inches 
tV Finished in sophisticated matt black 
•k Fully Guaranteed against any breakdown by 

our exchange unit scheme 
•k Completely designed and constructed by 

Miniature Electronics 
Send £10 without delay: Also available in Comprehensive 
Kit to build yourself £7, complete with full instructions. 

Build or buy a bug 
TX Mk1 — The latest in minia- 
ture Radio Transmitters. Have 
the time of your life with our TX 
Mki, use it for fun, Baby Alarm or 
Security. Supplied with all neces- 
sary information. 
•k 450 yard range 
ir Transmits even soft speech or 

a pin drop at 10 feet 
tV Completely self contained in 1" 

cube 
• Receive on VHF Radio 99-108 

MHz. 

tV Finished in matt black 
tV Operate from external PP3 bat- 
tery 30 hours life 
Send £8 for ready to use unit. Available in comprehensive 
kit form to build yourself £5. 

MINATURE ELECTRONICS LTD. 
64 LONGRIOGE ROAD, LONDON, S.W.5, 




INCOMPARABLE V.H.F. KIT 

Johnsons CV2 — unique triple-purpose (Converter, 
Receiver, Tuner-Feeder) kit for the Amateur enthusi- 
ast. Fantastic transistorized performance, World 
Wide Sales. Complete kit of top grade parts with 
coils covering 80-180 mHZ, plus easy/build diagrams 
and instructions;. £4 direct from makers or S.A.E. for 
free literature. 

JOHNSONS (RADIO) 

ST. MARTINS GATE 
WORCESTER WRI 2DT 

Est- 1943 Tel. 24864 

(A division of the G-BAN Organization) 



// you have difficulty in obtaining 

PRACTICAL WIRELESS 



a 



Please place 
your newsagent 



WL 



ith 



regular order 
or send 7 year's 
subscription (£265) to Subscription 
Department Practical Wireless, Tower 
House, Southampton St., London, W.C.2. 



704 




COMPREHENSIVE! 

MULTI-BAND ^ 

RECEIVERi^fiiaS^PpSfi 

PART 2 ' rJTY^ JPU\7\A*AA/U\A/\i\/U\J\JUJUl 



RF AMPLIFIER 

The circuit for this stage is shown in Fig. 5. The 
6BA6 is to the right of the ganged capacitor, Fig. 3, 
and LI is to the left, near the panel. In Fig. 5, LI is a 
"Blue" coil, and L2 the existing mixer "Yellow" coil. 

Leads run from VC6 and VC7 through the chassis 
as in Fig. 3. The aerial trimmer VC8 is fixed to the 
panel in the position shown in Fig. 4, hear the holder 
for LI. Arrange the valve and coil holders to allow 
short leads, with separation of grid and anode 
circuits, and earth the central spigot of the valve- 
holder to the chassis. 

The primary of L2 was originally earthed. Pin 8 is 
now disconnected from the chassis and wired to CI, 
Fig. 4, shown as C4 in the r.f. stage circuit Fig. 5. 
Pin 9 is disconnected from the aerial socket and 
connected to pin 5, VI, Fig. 5. 

A piece of co-axial cable is now used for the aerial 
circuit. Its inner conductor runs from the aerial 
socket to pin 8 of LI. The outer conductor is con- 
nected to the earth socket, chassis, and also to the 
chassis near LI. 

Add the r.f. gain control in the position shown, and 
disconnect R7 of the i.f. amplifier from the chassis, 
wiring it to VR1 and R4, Fig. 5. 

RF AMPLIFIER ALIGNMENT 

Insert a set of three coils. VC8 should peak quite 
sharply near the h.f. end of each band, unless the 
aerial is very long. Adjust the core of LI, in the way 
already described for L2, so that little or no adjust- 
ment of VC8 is required near the l.f. end of the band. 

There is no loss of efficiency if VC8 and VC3 can 




both be used to peak up signals throughout each 
band, and are not fully open or fully closed. But 
correct adjustment of the cores will make it 
unnecessary to adjust these trimmers frequently, 
except to peak up weak signals, or when changing 
the aerial or coils. 

When dealing with the highest frequency range, 
note that it is possible to tune LI or L2 to the wrong 
side of the oscillator frequency, at the h.f. end of the 
band. This effect is possible when trimming any 
circuit of this type, with an i.f. near 465kHz. LI and 
L2 should be tuned l.f. of the oscillator frequency, 
and the second channel, or unwanted response, will 
be about 930kHz h.f. of this, and will be found as a 
weaker signal, if a generator is used for alignment. 

On the lower frequencies it is not possible to set 
LI or L2 to the wrong side of the oscillator 
frequency. 

CARRIER OSCILLATOR/PRODUCT 

DETECTOR 

Fig. 6 shows the circuit of these sections. The 
product detector VI occupies the position near the 
last i.f.t. as in Fig. 3. The carrier oscillator is 
constructed completely in the box which is later 
bolted to the left of the chassis, Fig. 3. It is possible 
to use the carrier oscillator for the reception of both 
c.w. and s.s.b. using the diode detector Dl but recep- 
tion is much improved by switching it out and bring- 
ing in the product detector VI. 

The 3-way rotary switch controls operation of the 
receiver. Section SI allows the diode detector Dl to 
supply signals for a.m. reception, or switches to C5 
for s.s.b., c.w. and "Cali- 
brate." Section Sib applies 
h.t. to both stages in the 
s.s.b./c.w. and "Calibrate" 
positions. 

A 7X2in "universal 
chassis" flanged side is taken 
and its flanges cut away 2in 
from each end. It is then 
given right-angle bends 2in 
from each end, to make an 
open box 2in high, 3in wide, 
and 2in deep. A plate 3X2in 
is cut and bolted to the front 
flanges. 

The valveholder and CO 
coil are located as in Fig. 3, 
and all components in the 
box in Fig. 6 are assembled 
and wired, with tag strips to 
anchor h.t. circuits and other 

Fig. 5: Circuit of the r.f. amplifier, to 
give increased sensitivity. 

705 




components. A blue lead is run out from pin 4 for 
heater, a yellow lead from tag 1 for C6, and a red 
lead from C7 for h.t. circuits. 

A back plate 3 X 2in with a J 2 in flange to bolt to the 
chassis is bent up, or cut from a spare 5in wide 
"universal chassis" member. It is drilled so that it 
can be attached to the back of the CO box with four 
self-tapping screws into the flanges of the latter. 

The CO box is placed so that the bush and spindle 
of VC1, Fig. 6, project through a clearance hole in 
the receiver panel. It is fixed here by two bolts 
through the lower flanges of the box and chassis. 
The back plate described is then screwed on from 
behind, and is bolted to the receiver chassis. 

When VC1 is half closed the knob pointer or mark 
should be vertical. 

The function switch is put in the position shown, 
and h.t. and heater circuits connected. 

Most of the small components for the product 
detector are supported by the valveholder pins, and 
an adacent tag strip. The lead from C5 to SI runs 



Fig. 6: Circuit of the carrier oscil- 
lator and product detector to permit 
reception ofs.s.b. and c.w. signals. 

against the chassis. Keep 
grid circuits away from 
leads carrying heater 
current. 

After connecting CI re- 
align the last i.f.t. in the 
way explained. Tune in 
any transmission, with the 
switch at the "AM" posi- 
tion and place VC1 in the 
central position, as men- 
tioned earlier. 

Switch to SSB/CW and 
rotate the core of the CO 
coil until a strong hetero- 
dyne is produced. This is 
an audio tone which falls 
in frequency as the cor- 
rect core position is 
reached. Passing this posi- 
tion results in the tone 
beginning again and 
rising in frequency. The 
correct core setting is the 
central, zero beat setting. 
An audio tone which rises in pitch can then be pro- 
duced by rotating VC1 either way. 

When receiving s.s.b. the carrier oscillator has to 
replace the suppressed carrier, being adjusted 
slightly one way or the other, as necessary by VC1. 
The sideband normally employed depends on the 
amateur band in use, but the adjustment of VC1 will 
soon become clea::. 

For c.w. reception, use VC1 to obtain the most 
suitable pitch, placing the CO either above or below 
the c.w. as found to give least interference. 



CRYSTAL FILTER 

This incorporates an extra stage of i.f. amplifica- 
tion, 3-position selectivity switch, and variable 
phasing control using the circuit in Fig. 7. Tt provides 



HT+ 





This photograph of the underneath of the receiver can be compared 
with Fig. 4 (Part 1). r 

706 



tOOk 



Fig. 7: For increased gain and selectivity this crystal filter unit can 
be fitted. 



* components list 



RF STAGE:— 

ri Mm *w 

R2 47ki"2 1W 
VR1 lOkiiwii 



R3 «K>k<2 VW R5 150kil 1W 
R4 580 iW AH 10% tolerance 




CI tOOpF SM C3 (MflF 

C2 6-02/*F disc C4 (CI, Fig. 4) 

VC8 Front section ol handset capacitor 
VC? Front section of bandspread capacitor 
VC8 50pF variable 



if(L2) 

oils (Denco 'Yellow 



LI From basic 
12 Miniature p 
2, 3, 4 and 

Miscellaneous: 



CARRIER OSC/P. DETECTOR : 

R1 tOOkQ JW R4 22kO *W R7 *7M5 iW 

R2 820ii JW R5 33kQ 1W R8 47kli *W 

R3 47k! 2 JW R6 1 0OkQ ^W R9 47kii iW 




C2 4/xF 350V 

C3 470pF 

C4 470pF 

C5 2000pF 

VC1 15pF variable 

V1 12AU7 



C6 47pF SM 
C7 025/*F 350V 
C8 10ty*F'SM 
C9 lOOpf SM 

C10 140pF SM 



V2 mm 



Miscellaneous : 

Valveholders, B9A (1), B7G (1) with screen, S1a/b/ 
3 pole 3 way wafer switch (Sic is for crystal marker). 
Universal chassis flanged members 7x2in (1) 
•4/3in (Home P->d.oi i ', BF02/465 (Denco). 





CRYSTAL FILTER: 

Rt 2-7KO iW R3 68kl'2 j-W ■ R5 66ii 4W 

R2 100W2 ^W R4 47kf2 4W 

CI 0-02/tF -' 0-05/xF C3 02^F 

VC1 25pF variable 



Miscellaneous : 
V1, -6BA6. Crystal, 465kHz (see text). IFT, IFT11/ 
465/CT (Denco). S1, 1 pole 3 way wafer switch. 
Valveholder B7G and screen. Bushes (2) DL52C, 
coxip'incjs (2) DL60, im dia. polystyrene rod (Denco). 
Oniversal chassis side 7 '2in (1). 4v3in (t) (Home 
Radio). 



CRYSTAL MARKER: 

Rt 470W1 iW 

R2 10k!. 2 VW 



C1 220pF SM 
C2 002^F disc 
VC1 100pF variable 



C3 0-02/iF disc 
C4 100pF SM 



Miscellaneous 
Crystal, 1MHz. Valve. EF9 
Universal chassis side 4 
Crystal holder. 




additional gain, and a very great increase in 
selectivity. 

The i.f.t. has a centre-tapped secondary, and VC1 
can be adjusted to balance stray capacitance in the 
crystal and wiring, or to give a rejection notch either 
side of the crystal frequency. With the switch in 
position 1, the crystal is out of circuit, and selectivity 
is that provided by the three i.f.t.'s. With position 2, 
the crystal is in use working into the relatively high 
impedance of R3. For position 3, the crystal provides 
maximum selectivity. Position 1 is suitable for 
general reception and position 2 is used for other 
signals except when severe interference from 
adjacent transmissions is troublesome. 

A 3X2X2in box is made in the same way as des- 
cribed for the carrier oscillator. The circuit in Fig. 7 
is built entirely in this box, which is then bolted to 
the chassis, and closed by a plate fixed to the back 
with self-tapping screws. 

The i.f. transformer is situated above a hole in the 
main chassis, so that its lower core can be adjusted. 

VC1 must be insulated from the front of the box. 
and it is also mounted so as to avoid unnecessary- 




stray capacitance to the metal. This was done by 
punching a lin hole in the box and bolting a Tgin 
strip of paxolin across inside, with a hole to take the 
capacitor bush. The spindle is extended by using a 
small coupling and length of Uin diameter insulated 
rod, which runs through a bush at the panel. 

The 3-way switch is situated immediately under 
the box, on a chassis bracket and an extension 
spindle is also fitted. 

The exact frequency of the crystal is not too 
important, provided it falls near the frequency of the 
i.f.t.'s (465kHz). A 464kHz surplus crystal was used 
and a 455kHz crystal, available as a spare for a well- 
known communications receiver, also tried. No 
difficulty arose in adjusting the i.f.t.'s to 455kHz. 

A wire-ended crystal can be supported between 
pin 4 and VC1. Other crystals may need fixing to an 
insulated strip or bracket. 

Coloured leads pass down through the chassis to 
identify heater and other circuits. R2 runs to the 
common a.g.c. line. R5 is connected to the r.f. gain 
control, which now adjusts the bias of all i.f. stages. 

RF leakage round the filter will degrade the very 
high selectivity so the lead from the f.c. anode to 
i.f.t. primary is screened from the valveholder right 
up to the pin of the i.f.t. The anode lead of VI, 
Fig. 7, is similarly screened. 

707 



ALIGNMENT WITH FILTER 

Alignment should be checked with a meter, such 
as used earlier when adjusting the i.f.t. cores. A 
multi-range meter clipped in to read cathode current 
of one of the stages receiving a.g.c. is suitable, 
adjustments being directed towards securing mini- 
mum current. 

Set the phasing control about half open and the 
selectivity switch at 1. Tune in a strong transmission. 
Switch to position 2 and tune slowly across the 
signal, observing the tuning meter. There will 
probably be one normal response on the meter, ob- 
served as a steady rise and fall while tuning through 
the signal. A second response should be found, very 
much sharper, and probably giving only a small dip 
on the meter. This is the crystal frequency. Leave 
the tuning at this frequency, and adjust all the i.f.t. 
cores for best results (lowest meter reading). Switch- 
ing from 1 to 2 and tuning ' should show that the 
l.f.t.'s are now virtually on the crystal frequency. 
The phasing control is now adjusted slowly to find 
the exact point where selectivity is greatest and the 



HT+ 




-»-6«3V 



Note: Sic. is part of Sla/b 



Fi9 ,* : ,. As a P n 'sh[ng touch this 1MHz crystal marker will provide 
calibration points throughout the range of the receiver. 

response peak (or meter movement) approximately 
symmetrical a each side of the signal. Repeat this 
with the switch at 3, and adjust all the i.f.t. cores 
slightly, if necessary, with a signal tuned in precisely. 
Adjust the pointer of the phasing control so that it 
is vertical without moving the control itself. 

With the switch at 2 or 3, 'slight adjustments of 
VC1 one way or the other will produce a rejection 
notch which can be moved across the i.f. passband. 
This should be found to eliminate any interfering 
signal which is so near the wanted signal that it 
produces a heterodyne. 

CRYSTAL MARKER 

Fig. 8 is the circuit of the harmonic marker, which 
provides crystal-controlled "pips" from 1MHz to 
30MHz. TCI allows a slight shift in crystal frequency, 
so that the unit can be set to zero beat with MSF 
on 5MHz. HT is applied to the EF91 only when the 
function switch is in the "Calibrate" position. 

The marker is assembled on a sub-chassis which 
708 



is l 3 4 in. high, 4in. wide, and l^in. deep made from 
a single "universal chassis" member 4X3in cut to 
leave two pieces., one 4X 13 4 in and the other 4X H 4 in. 
The flange of the smaller piece is bolted to the 
straight edge of the larger piece, which can later be 
attached to the chassis by its flange. After wiring, 
it is bolted S^in from the rear edge of the chassis, 
behind the bandspread capacitor. 

The EF91, TCI, and crystal holder are mounted 
in line on the top of the sub-chassis with TCI in- 
sulated from the metal. This may be done by 
punching a hole which adequately clears the bush, 
and using two washers of Hsin paxolin. 

A small tag strip anchors C2, R3 and R4, and a 
flexible lead to pass to the function switch. C4 is 
similarly anchored, and a rigid insulated wire a few 
inches long is soldered here and runs near the 
ganged tuning capacitor. This was found to give 
adequate coupling into the receiver. 

A blue lead from pin 4 passes to the heater circuit. 
The chassis return is formed by bolting the marker 
to the receiver chassis. 

Initially place TCI about half closed. With the 
function switch at "Calibrate" the 5th harmonic at 
5MHz can be located with the appropriate coils in 
place. Switch off the marker and tune in MSF, which 
will probably be found on almost exactly the same 
frequency. If necessary, TCI is rotated so that the 
marker harmonic is on the same frequency. Turning 
TCI either way from this position will cause a flutter, 
rising to a low pitched growl or audio tone, the 
correct setting for VC1 being the central, zero 
position. 

The marker can be used for calibration, enabling 
the 1MHz tuning points to be marked in, from 1MHz 
to 30MHz. 

It also allows exact positioning of the handset 
capacitor, so thai: frequencies in a narrow band can 
be read with the bandspread tuner. To do this, turn 
the bandspread pointer to the nearest MHz reading, 
and adjust the handset capacitor for zero beat. This 
assures exact reading on the bandspread dial, which 
is not possible if the handset capacitor is adjusted 
visually. This procedure is used at 4MHz, 7MHz, 
14MHz, 21 MHz and 28MHz, for the 80, 40, 20, 15 
and 10 metre amateur bands. 

GENERAL NOTES 

A piece of thin perspex S^XS^in is used to cover 
the scales, held with chrome bolts. The perspex was 
held slightly clear of the panel by J 2 in wide strips 
of card at the bottom and each side. This allows 
slightly thinner card to be slid in, so that a separate 
pair of scales can be used with each set af coils 
There is sufficient space to take all the four ranges 
on a single permanent card, if preferred. 

The case top was cut to give an opening lid about 
ll^XTin. A line scribed ' 4 in from the back, li 2 in 
from the front, and 13 4 in from each side. A small 
drill is used to start a metal saw, to remove this 
piece. Strips about lin wide are bolted on inside 
the cabinet, for the piece removed to close upon, 
and it is secured along the back with a piano type 
hinge. 

Several i 2 in holes are punched in the case bottom, 
and along the back, for ventilation. Openings 
3 2 X li 2 in are cut for the aerial and other connections 
and the mains cord. This can be done by punching 
pairs of l> 2 in diameter holes, and sawing between 
them. M 



- _ 




PRACTICAL WIRELESS 




DECEMBER 1971 




This dictionary has been 
compiled to assist the 
reader in identifying the 
more common compo- 
nents that he will come 
across when constructing 
electronic equipment. It 
will also enable him to 
choose the correct com- 
ponent for a particular 
purpose. 



AERIALS, ferrite 

Ferrite rod aerials are universal in transistor radios and 
many other receivers, obviating the need for an external 
aerial. Inductors suitable for the medium and/or long 
wave ranges are wound on formers on a flat slab or round 
rod of ferrite material, the formers being movable on the 
rod for alignment purposes. These inductors take the 
place of the conventional inductors in the input circuit of 
the first stage of the receiver. 

Ferrite rod aerials have very pronounced directional 
characteristics having minimum pick-up off the ends of 
the rod and maximum pick-up at right angles to the line 
of the rod. This feature can be used to increase the 
strength of a signal or to null out an interfering signal if 
its direction is substantially different to that of the wanted 

signal. 

Ferrite aerials are obtainable for use in either valve or 

transistor circuits. 



CAPACITORS, fixed 

Any two metal objects (plates) separated by an insulator 
(dielectric) possess capacitance, or the ability to hold an 
electrical charge. Introduction of a solid dielectric in 
place of air increases the value of a capacitor by several 
times. 

Practical Units: The microfarad (/xF) and the picofarad 
(pF=1/1,000,000/iF). 

Electrolytic capacitors basically consist of two lengths 
of metal foil separated by a length of insulating material, 
the whole rolled up and sealed in a tubular container. 
During the process an electrolyte is introduced often in 
the form of a jelly. The foil may be aluminium or tantalum 
which may be etched in order to increase the "effective 
area and thus the capacitance. The insulating material 
will be as thin as possible consistent with the working 
voltage of the capacitor. All these measures are aimed at 
getting the maximum capacitance into the minimum of 

space. 

Electrolytic capacitors are generally polarised, one side 
(or electrode) always being connected to the positive side 
of the supply and the other electrode to negative. Generally, 
the outer case, usually of aluminium, is connected to the 
negative side although occasionally it is isolated. If the 
voltage is applied in reverse polarity the capacitor will 
almost certainly be badly damaged. Plus and minus signs 
or red and black markings are usually boldly marked on 
polarised electrolytic capacitors. 

It should be noted that non-polarised electrolytics are 



3= 



iOMPONENTS 

DICTIONARY 



included in the colour code marking. Hence these 
capacitors may be used to effect temperature compensa- 
tion of tuned circuits with a fair amount of precision. 
Care must be taken not to confuse these capacitors with 
the ceramic "High K" types which have a very high 
temperature co-efficient and are not particularly stable, 
being more suited for use as r.f. coupling and bypass 
capacitors. See table for colour coding. 



also obtainable but they are the exception rather than the 
rule. Electrolytic capacitors with as many as four sections 
are available such as 8+8+16+16>F usually with a com- 
mon negative connection, with the one unit being used for 
smoothing and decoupling purposes. Values of electro- 
lytic capacitors range from 0-25mF to lOOOO^F at working 
voltages from 2 5V to 600V. Tolerances on nominal 
capacity are not "symmetrical" as with resistors (±5%) 
but may be given as "-10% +50%" or "-10% +100%". 

Electrolytic capacitors are used in electronic equipment 
for smoothing purposes in mains rectifier circuits and as 
decoupling capacitors on h.t. and cathode circuits in 
valve radios, amplifiers etc. and as decoupling and coup- 
ling components in transistorised equipment. 

Fixed Capacitors (non-electrolytic) have several 
different forms of construction, each with its own special 
characteristics, which must be taken into account when 
selecting a capacitor for a particular application, so each 
type will be described separately. 

Silver Mica capacitors are considered very stable with 
a low temperature co-efficient and thus eminently suitable 
for use in tuned circuits. The working voltage is generally 
350V and capacity tolerance 1 or 2% with values available 
from 2-2 to 12000pF (0012j*F). 



Electrolytic 



/T 

i 

Outer 

foil 



JsJL ckJsJs 

TT 



Non 
polarised 

electrolytic 



Multi -section 



Feed through 



Polystyrene capacitors are cylindrical in form with the 
plastic film forming the dielectric. Possessing high insula- 
tion resistance, stability is fair and a negative temperature 
co-efficient makes these capacitors suitable for tem- 
perature compensation purposes in oscillator circuits. 
Also suitable for coupling and decoupling at radio 
frequencies. Capacitances available from 2-2pF to 0-1/*F 
with tolerances of 2± to 5% and working voltages of 125V 
or 250V. 

Polyester capacitors are also tubular, the dielectric 
this time being polyester plastic foil, again providing high 
insulation resistance and thus much superior to paper 
insulation in every respect. Stability is good and perfor- 
mance at r.f. fair. These capacitors can be used to replace 
paper ones in all non-critical applications. The range of 
capacitance is 0-01/tF to 0-5/xF with a tolerance of 10% 
and working voltages of 125V or 250V. 

Polycarbonate capacitors are somewhat similar to 
paper capacitors in performance, having poor stability and 
only fair capabilities from the point of view of r.f. per- 
formance. 

Ceramic, tubular capacitors have good stability 
characteristics together with known temperature co- 
efficients which may be positive or negative and sometimes 



CAPACITORS, variable 

Variable capacitors, like their fixed counterparts, come 
in a wide variety of sizes and values from the simplest two 
plate (vane) trimmer to the multi-section tuning capacitor 
with a total of perhaps 120 vanes. 

The moving plates or rotor are usually electrically part 
of the capacitor framework, the fixed vanes or stator 
being mounted in the framework on ceramic stand-off 
insulators to ensure minimum losses. Capacitors intended 
for use in oscillator circuits, where stability is most impor- 
tant, will have a rotor bearing at each end of the frame- 
work while a single front bearing is adequate for other uses. 
The spacing between the vanes may only be a few 
thousandths of an inch in the case of miniature variable 
capacitors such as are used in transistor radios while 
those used in small transmitters may have an air gap of 
a iin. depending upon the d.c. and r.f. voltages existing 
across the capacitor. In the process of miniaturisation 
the air dielectric is replaced by a plastic film considerably 
reducing the physical size of the unit for a given capaci- 
tance. 



Rotor 




2 -Gang 



Differential 



I 



Pre -set 



Ganged capacitors may have several sections mounted 
on a common spindle often with an end section of lower 
capacitance than the others, for use in the oscillator 
circuit of a superhet receiver. Each section will have a 
built-in compression type trimmer for alignment purposes. 
These trimmers are not generally shown on circuit dia- 
grams. Typical valu as for a two-gang unit are 176pF+208pF 
and, for a four-gang unit, 15pF+15pF+500pF+500pF, the 
latter being intended for use in an a.m./f.m. receiver. 

Differential capacitors have two stators arranged 
about a common rotor so that the capacitance of one is 
increasing while decreasing on the other, being, in effect, 
a capacitative potentiometer. 

The "law" of a capacitor relates the change in capacity 
with angular movement of the rotor, common ones being 
SLF (straight line frequency) and SLW (straight line wave- 
length). In each case the dial calibration will be approxi- 
mately linear. The law is determined by the shape of the 
rotor vanes. 

It is possible to obtain capacitors with integral slow- 
motion gearing obviating the need for a separate dial 
mechanism. 

Trimmer capacitors are generally similar in construc- 
tion to variable capacitors except that the spindle is short 
and slotted to take a screwdriver. Air spaced trimmers 
are not generally available in values greater than 150pF. 
Ceramic trimmers are two plate capacitors with the plates 
in the form of silver deposited on the ceramic base and 
ceramic disc rotor. The maximum value of this type of 
trimmer is mostly under 50pF. 



Compression type trimmers utilise mica or plastic film 
for the dielectric between a stack of plates the capacity 
being adjusted by means of a central screw altering the 
pressure on the plates. The minimum capacitance of this 
type of trimmer tends to be high but the maximum capaci- 
tance can be as much as 2000pF. Typical ranges are 10- 
80pF and 500-2000pF. These trimmers are commonly 
known as "padders" and are mainly used in the oscillator 
circuit of receivers. 



CIRCUIT BOARDS 

These are flat boards of insulating material on which 
components may be mounted and wired together to form 
electronic circuits. The insulation may be s.r.b.p. (synthetic 
resin bonded paper) or fibreglass. Boards may have the 
circuit printed on one side by depositing copper by 
chemical means, the components being interconnected 
with the circuit through small holes in the board. Copper 
clad boards having one side covered in copper can be 
used to form printed circuit boards by etching away the 
unwanted copper. 

Other boards (Veroboard) have a series of copper 
strips on one side with a matrix of holes, usually of 0-10* 
or 0-15* spacing, along the strips thus enabling com- 
ponents to be wired between the strips to form a circuit. 
Plain Veroboard is also available having the matrix of 
holes but no copper strips. Special pins are used with 
this board to which components and wiring may be 
connected. 

Edge connector sockets can be fitted to electronic equip- 
ment enabling circuit boards to be rapidly inserted or 
removed for servicing. 



DIODES 

A diode is a simple rectifier capable of passing current 
essentially in one direction only and hence may be used 
to rectify a.c. 




Bridge 



Thermionic 



Thermionic diodes consist of a filament or heater, 
constituting the cathode, surrounded by a metal cylinder 
or anode, all enclosed in an evacuated glass envelope. 
The diode may be a single unit or one or more may be 
incorporated with a triode or other valve. Power rectifiers 
consisting of two diodes, often with a common heater, are 
used in radio receivers and similar equipment to provide 
d.c. from an a.c. supply. Thermionic diodes or rectifiers 
are rapidly being replaced by silicon diodes which do not 
require a heater and are more efficient. 

Semiconductor diodes are generally of silicon or 
germanium with a point contact or a junction of semi- 
conductor materials. The smallest, a fraction of an inch 
long, are used for signal rectification and similar small 
signal purposes while the largest used in power supplies 
can pass several hundred amperes. Vast quantities of s.c. 
diodes are used in computers as high speed switches 
usually as part of integrated circuits. In a silicon diode 
the resistance in the forward direction is very low and 
high in the reverse direction. In a germanium diode the 
resistance in the reverse direction is appreciably lower 



niyn in ihb 

resistance i 



than that of a silicon diode. 

Semiconductor diodes are marked with a spot or a 
band or a plus sign indicating the end of the diode that 
will show a positive voltage when an a.c. voltage is applied 
to the diode. This end corresponds to the cathode in a 
thermionic rectifier. 

A characteristic of diodes, quoted in maker's data, is 
the "peak inverse voltage" (PIV). This is the maximum 
peak voltage allowable across the diode during the non- 
conducting part of its operating cycle. In practice the p.i.v. 
will vary between 1-4 and 2-8 times the applied r.m.s. 
voltage depending upon the type of rectifier circuit 
employed. 



INDUCTORS 

While a straight wire possesses "inductance" the value 
of this inductance will be considerably increased if the 
wire is formed into a coil or inductor. An iron dust core 
inserted into the inductor will further increase this induct- 
ance. 

Practical Units: The henry (H), the millihenry (mH = 
1/1000H) and the microhenry (^H=1/1,000,OOOH). 

LF Inductors, or chokes, are a single winding on an 
insulating former having a laminated core (see Trans- 
formers). The inductance will range from one or two 
henrys to around 50 henrys or so. These chokes offer high 
impedance to low frequencies and are used in audio 
amplifiers and filters, loudspeaker networks and as 
smoothing chokes in mains rectifier circuits. 

RF Inductors, or coils, have a single winding, either 
layer or pile wound, on a low-loss former and may include 
an adjustable iron dust core for varying the inductance. 
If the coil is wound with heavy gauge wire the turns may 
be self-supporting. Windings of comparatively few turns 
may be added to the inductor to couple it to other circuits 
or to provide a feedback winding for use in oscillators. 

Such inductors, with associated tuning capacitors, 
are found in r.f. amplifier, mixer and oscillator stages of 
receivers as well as in transmitters and signal generators 
and other test equipment. Although they are usually 
permanently wired into circuit they can be obtained 
mounted on a plug-in base for rapid coil changing. 

The "goodness" or "0" of an inductor may be enhanced 
by enclosing it in a ferrite "pot" with or without an adjust- 
able iron dust core. 



8 

o 
o 



RF 

Air core 



2" 

f 



RF 
Dust core 



Adjustable 



LF 
Iron core 



RF Chokes are inductors having a single winding, some- 
times on a ferrite core, and of sufficiently large inductance 
to presenta high impedance to specified radio frequencies. 
The winding may also be in the form of several separated 
pile wound sections in order to reduce the self-capacitance 
of the choke. 

Values of inductance range from a few microhenrys for 
v.h.f. workto 30 millihenrys forthe lower radio frequencies. 



INTEGRATED CIRCUITS 

The integrated circuit is produced by methods similar to 
those used in transistor manufacture and combines a 
number of discrete components on the one silicon chip. 
Apart from the transistors or diodes, resistors, capacitors 

iii 



iOMPONENTS 

DICTIONARY 



and inductors can be formed as well as the necessary 
interconnections. 

Linear i.c.'s include wideband, audio and operational 
amplifiers while digital i.c.'s are used in frequency 
counters, digital clocks, computers etc. 

Integrated circuits may be encapsulated or mounted in 
metal cases. Lead-out wires or tags enable the device to 
be directly wired into a circuit board or plugged into a 
suitable holder. 



PHOTOCONDUCTIVE CELLS 

These devices are sensitive to light, either producing a 
voltage when subjected to sunlight as in the case of 
selenium and silicon photocells, or varying their internal 
resistance as with cadmium sulphide photocells. The 
latter are also known as light-dependent resistors (LDR). 

The silicon and selenium cells will deliver enough power 
to operate a transistorised radio or even a small electric 
motor, a single silicon cell providing nearly half a volt at a 
current of 15mA. 




With LDR's the effect of the varying resistance with 
changes of incident light can be amplified and used to 
actuate an alarm or counter or similar device. A typical 
LDR is the ORP12 which has a "dark resistance" of several 
megohms falling to a few hundred ohms with full illumin- 
ation. 



RESISTORS, fixed 

Every electrical circuit possesses "resistance" which 
limits the current flowing in the circuit. Resistors of known 
value are used to introduce resistance into circuits, 
usually to a pre-arranged design. 

Practical Units: The ohm (Q), kilohm (kn=1000fi) and 
the megohm (MO=1, 000,000ft). 

Fixed resistors (carbon) are moulded from a special 
carbon composition, the connections to the resistor being 
in the form of wire ends. Resistors are given a wattage 
rating by the makers which represents the maximum power 
that the resistor may safely dissipate. Wattages generally 
available range from i watt to 2 watts in values from 1 ohm 
to 22 megohms. 

The tolerances available on the nominal value are usually 
plus or minus (±) 5 and 10% although 20% was common 
in the recent past. 

The stability of composition resistors is poor but their 
performance at radio frequencies can be considered fair 
while their change of value with change in temperature 

iv 



(temp, co-efficient) is poor being about ten times worse 
than a wire-wound resistor. Such resistors should only be 
used in non-critical applications. 

High wattage carbon resistors, 25W or more, are often 
used as non-inducti /e loads for transmitters and amplifiers 
although they are somewhat difficult to obtain. Construc- 
tors can improvise by series/paralleling lower wattage 
resistors until the required value is obtained. 

Fixed resistors (metal oxide/carbon film) are formed 
by deposition on to a ceramic tube or rod, their main 
advantage being that of high stability. Tolerances are 
generally 1 or 2%. 

Their performance at r.f. is good although care should 
be taken in using them at v.h.f. or u.h.f. since the metal film 
is often in the form of a spiral which can introduce appreci- 
able inductance at these frequencies. These resistors are 
particularly suitable for audio amplifiers and circuits where 
a low noise level is essential. 

Fixed resistors (wire-wound) are composed of a layer 
of resistance wire on a ceramic tube or rod, with clips or 
wire ends, and generally having a coating of vitreous enamel 
or something similar. Some versions have one or more 
movable clips so that intermediate values of resistance 
can be had. 

Wire-wound resistors must not be used in r.f. circuits 
since by the very nature of their construction they are highly 
inductive. Those wilh special windings and termed "non- 
inductive" should also be treated with some suspicion at r.f. 
On the credit side these resistors have a very low noise 
characteristic and low temperature co-efficient compared 
to carbon resistors. 

— ^vwvVv — — lIUIJIj — — i i — 

Non-reactive 

Wire-wound resistors are available to the constructor in 
ratings from 1W to around 50W and in values from 022ft 
to 100kO usually with a tolerance of 5%. Mains "dropper" 
resistors are a special breed of wire-wound resistor used 
in transformerless radios and TV sets and fitted in series 
with the valve heater chain. They may have adjustable 
clips or tapped sections. 

Resistor values, fcr carbon resistors, are indicated by a 
colour coding, details of which are given in the accompany- 
ing table. If a tip or spot colour appears to be missing it can 
be assumed to have the same colour as the body of the 
resistor. For example , a resistor which is red all over has a 
value of 2-2kft and one with an orange body and a yellow 
spot only is 330kft. 

The actual values of resistors in common use conform to 
the "E12 Series" of twelve values and their decades (see 
table) but there is also the "E24 Series" with a further 
twelve values intermediate with the E12 series. These are: 
1-1, 1-3, 1-6, 2-0, 2-4, 30, 3-6, 4-3, 5-1, 6-2, 7-5 and 9-1 
and their decades. 

Wirewound resistors usually have their value marked in 
plain numbers. 



RESISTORS, variable 

Like fixed resistors, these use either carbon composition 
or resistance wire for the resistance element. The moving 
arm or rotor moves over the element thus enabling any 
value between virtually zero and the value of the variable 
resistor to be selected. The rotor spindle is extended to 
take a control knob where frequent adjustment is required, 
such as with a volume control, or may be short and slotted 
for adjustment with a screwdriver as a preset control. 
Potentiometer or "pot" is the general name given to such 
variable resistors. 



Carbon potentiometers have a moulded composition 
track or a carbon deposit on an insulating ring. The rotor 
contact, generally with two or more "fingers" to ensure 
continuous pressure on the track, is usually isolated 
from the spindle. 

The amount of resistance in circuit relative to the 
angular movement of the rotor constitutes the "law" of 
the potentiometer. If equal resistance change results 
from equal angular movement of the rotor the potentio- 
meter is said to be "linear". If the change is logarithmic 
the potentiometer is "log" law. If checked on a test meter 
such a potentiometer would show little change in 
resistance at the beginning of the movement (clockwise) 
and a very rapid change towards the end of the movement. 
An "anti-log" potentiometer will show the reverse effect. 

Log potentiometers are generally used as volumes 
controls on radios and audio amplifiers since the human 
ear responds to sound levels on a logarithmic basis. 
Such a volume control will appear to give equal changes 
in sound level for equal movement of the control. 

Potentiometers can be obtained ganged together with 
a common spindle or with concentric spindles for in- 
dependent operation. On stereo amplifiers ganged 
potentiometers are used for volume controls, filter 
adjustments, balancing and similar circuits where both 
amplifiers must be adjusted simultaneously. It is common 
practice to fit a volume control with a single or double 
pole mains on/off switch operated by the rotor of the 
potentiometer at the beginning of its travel. 



Values of carbon potentiometers go from around 100X2 
to about 2MCJ. Wattage ratings are not always quoted 
since these controls are not usually called upon to pass 
any appreciable current. 

Pre-set carbon potentiometers may be of completely 
enclosed construction or open skeleton type. The latter 
generally have wire lead-outs or tags suitable for direct 
mounting on circuit boards. 



Variable 



/ 




1 



Variable Pre-set 



Pre-set 



T 

Pre-set 




^®® ? s 



A B C D 



B C A D 
Body— Tip— Dot 



Tubular |J 
capacitors 



Wirewound potentiometers are similar in most 
respects to the carbon ones except that the resistance 
element consists of resistance wire wound on to a flat 
insulating strip which is then formed into a ring, the rotor 
generally moving round one edge of the ring. 

Values of these potentiometers of interest to the con- 
structor run from 10fl to 100kQ in ratings from 1 to 3W. 
Again, mains on/off switches can be fitted if required. 

Precision wirewound potentiometers have the winding 
in helical form needing perhaps ten or more turns of the 
control spindle to cover the whole winding. A turns 
counter is fitted to the spindle. Preset wirewound poten- 
tiometers for use on circuit boards have a straight winding 
with a sliding contact operated by a screw thread, the 
whole enclosed in a plastic moulding. For use in adverse 
conditions of dirt or moisture both carbon and wirewound 
potentiometers can be had as hermetically sealed units. 



SWITCHES 

The simplest device for making or breaking a circuit is 
the on/off switch and from this devolves a multiplicity of 
types. 



COLOUR CODE FOR CAPACITORS AND RESISTORS 



Black 

Brown 

Red 

Orange 

Yellow 

Green 

Blue 

Violet 

Grey 

White 

No colour 

Silver 

Gold 



First 

Figure 

'A' 



Sec'd 

Figure 

'B' 



Multiplier 
•C" 



Resistors 



1 

10 

100 

1,000 

10,000 

100,000 

1,000,000 

10,000,000 

100,000,000 

1 ,000,000,000 



Caps pF 



1 

10 

100 

1,000 

10,000 



0-01mF 
0-1/aF 



Tolerance 'D' 



Res 



±1% 

±2% 



±20% 

±10% 

±5% 



Ceramic Capacitors 
to 10pF over 10pF 



2pF 
1pF 



0-5pF 



0-25pF 

IpF 



±20% 

±1% 

±2% 
±2~% 

±5% 



±10% 



A salmon-pink fifth ring or body colour denotes a Grade 1 high-stability composition resistor. There are variations 
in the code for capacitors other than ceramic tubular types. 



The "preferred" series of values is as follows:-! 1-2 1-5 1 -8 2-2 2-7 3-3 3-9 4-7 5-6 6-8 8-2 and their decades. 




COMPONENTS 

DICTIONARY 



Toggle switches have a laminated or moulded body 
with a metal or insulated dolly or operating lever. Switch 
contact combinations include single pole, single throw, 
(s.p.s.t.), double pole, single or double throw (d.p.s.t. and 
d.p.d.t.) and double pole change-over. Some types are 
obtainable with a centre off position. The dolly may be 
slotted for operation from a cam on an associated control. 
Other variations include biasing in one position, terminal 
or tag connections and instrument type toggles which 
are designed to have very low contact resistance for 
instrument use. 

The ordinary toggle is designed to carry 3A at 250V 
a.c. with other ratings up to 10A. 

Other switches performing the same function as toggle 
switches include rotary toggle switches, miniature slide 
switches and press button switches although these are 
generally s.p.s.t. only. 



°>o v v V 

cr O Q O O O O O D O 

To° K K K 



O O 
1 pole 12 way 



\ 



SP 
on/off ■ 



DP 
on/off 



3 pole 4 way 

? ? 

DPDT 



Microswitches are button operated switches capable 
of operation with pressures as low as 1 ounce usually by 
means of a lever or similar attachment. Contact arrange- 
ments are fairly simple, on/off or s.p.d.t. the contacts 
themselves handling 6A at 12V a.c. or 3A at 250V a.c. 
although models are obtainable for up to 10A. 

Wafer rotary switches consist of a flat ring of paxolin 
insulating material with fixed contacts riveted around the 
periphery. A disc in the centre of the ring carries the rotor 
contacts, the disc being rotated by a spindle attached to 
an index plate. The maximum number of fixed contacts is 
generally 12 with a maximum of four on the rotor giving 
various combinations such as 1 pole, 12 way to 4 pole, 
3 way. 

Since the wafers are very thin several may be mounted 
on one spindle, sometimes with metal screens between 
sections to reduce unwanted coupling. These switches 
are widely used as wavechange switches on radios, audio 
filters and tone control circuits as well as in meters and 
test equipment. 

Mains switches are available for use with wafer switch 
assemblies since the wafers themselves should not be 
used for this purpose. The contacts are not designed to 



carry any appreciable current. Wafers in ceramic or other 
low-loss materials are available for switching r.f. circuits. 
The switches can be bought as complete units or the 
individual wafers and parts obtained and assembled to 
suit particular requirements. 



THERMISTORS 

Thermistors are a special kind of resistor having a 
pronounced negative temperature co-efficient. They are 
used in circuits, such as valve heater chains, to restrict 
initial current surges when first switching on. The initial 
high resistance of the thermistor drops logarithmically 
as the protected device warms up. 



VV^Ar— 

Neg. temp co-sffic. 



— w#w— 

Pos. temp co-effic. 



The thermistor is. also used to protect photo flood 
lamps from current surges and in temperature sensitive 
fire alarm systems. Audio signal generators and oscillators 
utilise the thermistor in feedback circuits to provide a 
constant output. Bead type thermistors are used in these 
circuits since their reaction time to current changes is 
comparatively short. Bead types can also be employed in 
measuring r.f. power especially at very high frequencies. 

Thermistors in general use have current ratings ranging 
from 2mA to 2A. 



THYRISTORS 

Also known as silicon controlled rectifiers (SCR) the 
thyristor is basically a silicon diode rectifier with an 
additional electrode or "gate" which is used to control 
the current flowing through the thyristor. A pulse applied 
to the gate can switch the thyristor on or off. Once the 
thyristor is conducting a minimum current is required to 
maintain conductior. 



gate 



| anode | 

I cathode 




Thyristors used by the constructor will have current 
ratings between 1 and 10A and peak voltage ratings up to 
600V. The p.i.v. figure required for a particular application 
will be approximately 1£ times the applied r.m.s. voltage. 

The gate trigger circuit will need to provide a voltage of 
the order of 3V at a current of up to 20mA. Small current 
thyristors are genera ly contained in a T05type metal case 
with wire lead-outs while the larger thyristors have a stud 
mounting and tag connectors. 



TRANSFILTERS 

Transfilters are ce'amic filters having somewhat similar 
characteristics to those of the conventional i.f. transformer. 
Several transfilters may be combined with capacitors to 
provide specified bandpass filter features. Several types 
of transfilter are available around 455kHz as well as for 
10-7MHz for use in the i.f. stages of f.m. receivers. Since 
transfilters do not require any alignment in a receiver they 
are gradually replacing the tuned i.f. transformers in 
commercial receiver;;. 



§StiwO- ; ■?;■'•■ ■ 




TRANSFORMERS 

Basically two coils coupled together so that an alter- 
nating current in one coil, the primary, will induce an 
alternating current in the second coil, the secondary. The 
ratio of the input voltage, producing the current in the 
primary, to the voltage at the secondary is directly propor- 
tional to the turns ratio of the two coils. 

In this way the transformer can be used to match one 
impedance to another. 

LF Transformers are wound on a laminated core of 
ferromagnetic material, the laminations being electrically 
insulated from each other. Mains transformers may have 
extra windings for valve heaters, pilot lamps etc. as well 
as taps on the primary winding to accommodate variations 
in mains supply voltages. 




■ c 




e> 


o 






















C> 


Rf 




All 


c 


ore 




RF Transformers have coils wound in layer or pile- 
wound form, or air-spaced, on insulating formers often 
with iron dust cores or slugs to enable each winding to be 
separately tuned. 

IF Transformers are similar to r.f. transformers, being 
designed to work at the fixed intermediate frequency in 
superhet receivers, usually between 450 to 475kHz or 
around 1-6MHz. As well as dust cores each winding 
generally has a fixed capacitor across it in order to obtain 
the optimum inductance to capacitance ratio. 






RF-IF 



Autoiransformers have a single tapped winding the 
ratio of the turns each side of the tap providing the required 
transformation ratio. One winding may be common to both 
circuits providing an alternative ratio. Note that an auto- 
transformer does not provide the isolation obtainable with 
a double wound transformer. A common form of auto- 
transformer is the Variac used for compensating changes 
in mains supply voltages. 



e: 

61 



Power 




Toroid 



Toroid transformers have the windings wound on an 
annular ferrite core. The separate wires comprising the 
windings are laid or twisted together and then wound 
round the ferrite ring. On the circuit symbol the start of 
each winding is marked with a dotto assist in identification. 



TRANSISTORS 

The transistor is a three electrode semiconductor device 
capable of amplifying an electrical signal. The semi- 



conductor materials used in making transistors are either 
silicon or germanium although there are others such as 
selenium. 

The pure silicon or germanium is treated with either of 
two impurities in minute quantities to produce 'p' and 'n' 
type silicon and germanium. A junction of silicon p and n 
material will show a high resistance in one direction and 
a low resistance in the other thus forming a diode. A 
germanium diode similarly formed will not show such a 
wide change in resistance. 

A p-n-p transistor is formed from a thin slice of n 
material sandwiched between two pieces of p material, 
the slice being known as the base and the p material as 
the emitter and collector respectively. An n-p-n transistor 
has a slice of p material between two pieces of n material. 

With an n-p-n transistor the emitter voltage must always 
be negative with respect to the collector and the emitter 
of a p-n-p transistor positive with respect to the collector. 
N-P-N and p-n-p transistors can have very similar 
characteristics in which case they are said to be 
"complementary". 

Many different processes are used in the manufacture of 
transistors producing devices of widely varying charac- 
teristics and types: 

Alloy transistors were among the earliesttypes produced. 
The germanium alloy transistors are cheap to produce 
but do not have a very good performance at high fre- 
quencies. They are widely used as power transistors since 
their low resistance permits the maximum current to be 
passed at low voltages. Silicon alloy transistors are used 
mainly because of their ability to operate at high tem- 
peratures. 



collector 





gate 




source 
p-channel 
junction gate 



n- channel 
junction gate 





npn 



n-channei 
insul. gate 



p- channel 
insul, gate 




Alloy-diffused transistors have improved performance 
with a cut-off frequency of the order of 100MHz and being 
cheap to produce are widely used in radio receivers. 

Mesa transistors with a cut-off frequency of over 
1000MHz are among the best at high frequencies. 

Planar and epitaxial planar transistors have been 
developed to reduce the collector leakage current and also 
to include a shield to reduce the capacitance existing 
between the collector and base electrodes. 

Field effect transistors are unipolar as distinct from 
those listed above which are bi-polar. F.E.T.'s are more 
akin to the thermionic valve than any previous transistors. 
While bi-polar transistors are essentially current operated 
devices and have a low input resistance f.e.t.'s are voltage 
controlled and consequently have a very high input 
resistance. The controlling "gate" may be either a junction 
type (j.u.g.f.e.t.) or insulated type gate (i.g.f.e.t.) either 
type being obtainable as p-channel or n-channel f.e.t. The 
i.g.f.e.t. is also known as the metal oxide silicon f.e.t. 
(m.o.s.f.e.t.). 

vii 



COMPONENTS 
DICTIONARY 



VALVES 

Thermionic valves contain a filament or heater/cathode 
which emits electrons, with one or more other electrodes, 
all contained in an evacuated glass envelope. The four 
basic types of valve are the diode, triode, tetrode/pentode 
and frequency changer or mixer. 




Screen ; 

grid I __^_ 




"etrode 



^ 



Pentode 



Pi 

Triode Pentode FC Octode FC 



w 




Double diode 
triode 



Full wave 
rectifier 



The Diode comprises the cathode and a metal plate 
or cylinder called the anode. Small single or double diode 
units are used for signal rectification in detectors and 
a.g.c. circuits. Larger single or double units are employed 
in half and full wave power rectifier circuits. A special use 
for diodes is in the line scanning circuits of TV sets 
where they are known as "efficiency diodes". 

One or more diodes are frequently found in a common 
structure with triodes and pentodes where they are associ- 
ated with the signal circuits. 

The Triode has a wire mesh, the signal grid, placed 
between the cathode and the anode. A negative voltage 
on the grid controls the anode current enabling the triode 
to be used as an a.f. amplifier or oscillator at a.f. or r.f. 
A triode is commonly incorporated with a pentode where 
it acts as a preamplifier. 

The Tetrode has a second grid placed between the 
signal grid and the anode. This "screen grid" reduces 
inter-electrode capacitance and overcomes a deficiency 
of the triode known as the "space charge effect". 

The Pentode has yet another grid, the suppressor grid, 
between the screen grid and the anode, which eliminates 



the kink in the characteristic curve of the tetrode caused 
by secondary emission. In "beam" tetrodes this third grid is 
omitted but its effect is simulated by the careful placement 
of the anode with respect to the other electrodes. Tetrodes 
and pentodes are used for both r.f. and a.f. work. 

Frequency changers, or mixers, are used in superhets 
to produce the intermediate frequency (i.f.) from the input 
signal and the local oscillator signal. The mixer valve 
takes the form of a pentode or tetrode with additional grids 
to which these signals are applied. Some frequency 
changers incorporate a separate triode for the local 
oscillator feeding internally or externally into the mixer 
section. 

Battery type valves have 1 -4V filaments for operation 
from a single cell, taking a current of 25 or 50mA. The 
maximum anode voltage is generally 90V. Valves fed from 
a mains supply may have 6-3V heaters which are connected 
in parallel each heater taking anything from 200 to 600mA. 
Dual section valves sometimes have heaters with a centre 
tap allowing operation in series on 12-6V or in parallel 
on 6-3V. 

Other mains operated valves have the heaters in series 
based on a common current of 100, 150 or 300mA with 
individual heater voltages of 4 up to 50V. In a.c./d.c. 
receivers and TV sets the heater chain may be connected 
across the mains, tne difference between the sum of the 
heater voltages and the mains voltage being taken up by 
a "dropper" resistor (see Resistors, fixed). 



VARICAP DIODES 

Varicap Diodes, sometimes known as varactors, are 
similar to semiconductor p-n junction diodes in that the 
capacity existing between the regions varies with the 
applied reverse voltage. Varicap diodes provide known 
changes of capacity over a given range of reverse voltage, 
typically 50 to 10pF for a range of 1 to 20 volts. 



-HW— 



Hh 



These diodes car thus be used to tune r.f. circuits by 
means of a potentiometer controlling the applied reverse 
voltage. They are useful up to frequencies of several 
hundred MHz and are currently being employed commer- 
cially in v.h.f. receivers and t.v. tuners. 



ZENER DIODES 

The zener diode is: a semiconductor diode which breaks 
down and conducts when a voltage applied in the reverse 
direction reaches a predetermined value. The action is 
somewhat similar tc that of a gas filled voltage stabiliser. 

The external circuitry of a zener diode must be designed 
so that its rated power dissipation is not exceeded. 




Zener diodes of interest to the constructor are available 
with nominal zener voltages ranging from 2-4V to 200V 
with tolerances from 5 to 20% and dissipations from 
200mW to 20W. Those diodes are used as voltage stabi- 
lisers, voltage reference sources, limiters etc. 

The end of a zener diode intended to be connected to 
the positive side of a supply is usually marked with a spot 
or band or a plus fiign. 



viii 



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ALL IN THE JANUARY 
ISSUE ON SALE DEC. 3rd. 




PART 3 



H.W.HELLYER' 



Circuits and Parameters 

That ugly word 'parameters' frightens many new- 
comers — and really, it need not, for it is only the 
guideline along which we can walk as we follow the 
curious path of transistor development. There have 
to be some hard-and-fast rules, and these are the 
parameters. 

Transistors can be of p.n.p. or n.p.n configuration, 
the essential difference, in practice, being polarity 
of the supply voltage. The three basic modes are 
common-base, common emitter and common-collector. 
The last is more conveniently referred to as emitter 
follower, for reasons we shall explain. Some of our 
circuits show p.n.p. transistors, some n.p.n. — we must 
get it into our heads at the outset that the essential 
difference is polarity, and this makes it easy to com- 
bine the two types in one circuit. 

The common-base circuit is a good introduction to 
transistor technology. Here, a small change in emitter 
current brings about a small change in collector 
current. The ratio between the two is the current 
transfer ratio, alpha (%). 



In symbolic form : a = - — 
SIe 

where delta (S) denotes change, in this case, increase. 
In some formulae, the symbol A may be used instead 
of H. 

Figures for alpha are very near, but not quite, 
unity. For a germanium device, typically 0-98. 

Take Fig. 9, a proving circuit to demonstrate the 
above formula. Here we have a common-base tran- 
sistor connected so that the emitter current flows, 
around 0-5mA. Voltage V,. : establishes this. The 
emitter junction for an average transistor will be 
around 100 ohms. The collector current, I C) flowing 
through the load R L , will be slightly lower than the 
emitter current. Between base and emitter — the base 
being earthed, or common, a 1-5 volt battery biases 
the emitter positively. 

The input voltage, V IN) depends on the setting of 
the variable resistance, R, N , which has a further 1-5 

710 



volt battery across it, again biasing the emitter posi- 
tively. The proportion of voltage across the base/ 
emitter junction aided by the position of R IN in 
series with V E represents the increase 8I E . 

The emitter junction resistance of a typical small 
signal transistor is about 100 ohms, and let us sup- 
pose that the load resistor is 10000 ohms. Thus the 
change at the input is 10/xA through a resistance of 
100 ohms, but the change at the output is 9-8,uA 
through a resistor of 10000 ohms. The result, from 
Ohm's Law, is a voltage change across R L of 98m V 
for a change in voltage at the input of lmV. This 
gives us a voltage gain of 98 times in spite of a 
slight loss of current flowing out through the base 
contact. 



rtF®~l; 



V|N 

1 



Vr 



V C 



Fig. 9: The common-base circuit arranged to demonstrate change in 
emitter current causing change in collector current. 

With the more frequently used common-emitter 
circuit, the current transfer ratio is the ratio of cur- 
rent change at the base to current change at the 
collector, and is designated fi (beta) (or sometimes a'). 
These parameters. /? and 7, are mathematically re- 
lated, the relationships, for those wishing to look 
further into this being : 

and a = 



(1-a) 



(1+0) 



The figures quoted by manufacturers are for small- 
signal operation unless otherwise stated. 

Another commonly seen transistor parameter is the 
transition frequency, designated f T . This is the fre- 
quency at which the common-emitter current gain 
falls to unity, and gives an indication of the fre- 
quency limits of the transistor. 



Hybrid Parameters 



Hybrid parameters are widely used in the semi- 
conductor industry to specify transistor characteris- 
tics. They are a set of resistance, admittance and 
voltage and current ratios for given conditions (hence 
the term hybrid). In the case of the common-emitter 
circuit these h parameters are : 



h lc :- 
h, t . : 
h, e :- 
h 0P : 



input resistance, common emitter, output 
short-circuited. 

reverse voltage feedback ratio, common 
emitter, input open circuit, 
forward current gain, common emitter, out- 
put short-circuited. 

output admittance, common emitter, input 
open circuit. 



If one group of parameters is known, for one 
circuit configuration, it is possible to work out the 
others. In practice, however, such information is 
more useful to the designer than to the engineer or 
constructor, who chooses replacement transistors on 
more empirical hues than a comparison of detailed 
parameters. 

Characteristics of Basic 
Configurations 

Approximate characteristics of the three basic 
circuit configurations are summarised in Table 1. 
These must be taken as a guide only, not as 
accurate conditions for a particular transistor. The 
table indicates the orders of magnitude of the main 
parameters with the three configurations: actual 
figures will of course vary considerably with different 
types of transistor. 

TABLE 1 Features of Circuit Configurations for Comparison 





Common 


Common 


Common 


Characteristic 


Base 


Emitter 


Collector 


Input to 


Emitter 


Base 


Base 


Output from 


Collector 


Collector 


Emitter 


Current Gain 


Less than unity 


About 50 


About 50 


Voltage Gain 


High (approx. 


High (approx. 


Low (approx. 




250) 


250) 


D 


Input Imped- 


Low(200Q) 


Medium 


High (lOOkft) 


ance 




(1000Q) 




Output Imped- 


High (200kQ) 


Medium 


Low (1000Q) 


ance 




(40kQ) 




Power Gain 


Medium 
(30dB) 


High (40dB) 


Low (16dB) 


H.F. Response 


High (400kHz) 


Low (12kHz) 


Dependent on 


(Power ...3dB 






source and 


down) 






load resis- 
tances 


Phase Shift 


0°— Output and 


180° 


0° 




input in 


(inverse) 


(in phase) 




phase 







It will be noted that the details given in Table 1 
include power gain and phase shift, the latter stated 
to show the effect of the different configurations on 
the polarity of the signal. This last factor is too often 
overlooked when experiments are made. Another im- 
portant factor, not. given in the table, but necessary 
for the designer, is the comparison of collector leak- 
age current with the three configurations: except in 
the common base configuration, this is dependent 
on the resistance in the base circuit. 

Output Characteristics 

As can be seen from the output characteristic set 
of curves of Fig. 10, circuit configuration makes quite 




a difference to collector voltage and current rela- 
tionships (compare these characteristics with the 
basic pn junction characteristic shown in Fig. 6, 
Part 1). When considering the choice of a replace- 
ment transistor or working out a design it is neces- 
sary to take a set of output characteristics, i.e., a 
family of curves for different base currents — and plot 
a load line as shown in Fig. 11. It can be seen that 
with a common emitter circuit when the base current 
is zero the voltage between emitter and collector is 
almost the full supply volts, i.e. collector current is 
very small. (It is actually the reverse leakage cur- 
rent of the collector junction.) 




Fig. 10: Typical characteristics showing how circuit configuration 
drastically alters collector voltage and current relationships. 

Increasing base current causes an increase of col- 
lector current; the voltage across the load resis- 
tance increases and the voltage across the transistor 
decreases. Eventually, as the base current is in- 
creased to a state when the collector current causes 
a voltage across the load almost equal to the supply 



X Y= Load line 



Base current 



2-5- 

a. 


s bUpA 


c 2«0< 
Z 

L. 

3 . - 


**fk 






40pA 


Collector c 
(Jl O u 




^•^p 




30pA 


~j mm ■ i' s \ * upA 




1 


^^A 


10pA 




1 1 i 1 1 — "N^ — i 



4 6 

Collector volts, V 

Fig. 11 : Constructing a load line for a transistor gives its case history 
for design purposes. 

voltage, the voltage across the transistor drops to 
practically zero. Any increase of base current beyond 
this point gives no further increase in collector cur- 
rent — the transistor is saturated. This, for a transis- 
tor of given characteristics, is at point B in Fig. 11. 
The load line, drawn through points X to Y passes 
through this point B. Point X is the maximum supply 
voltage and point Y the current resulting from divid- 
ing the supply voltage by the load resistance. In the 
example, a supply voltage of 12 volts and a load 
resistor of 6000 ohms gives a collector current at Y 
of 2 mA. 

From this load line, the transistor operating point 
can be chosen by adjusting the base current to a 
value between the two extremes of A and B. The 

711 



best choice is midway along the load line, i.e. at P, 
where collector current is 1mA and collector volts 6. 
Since the current gain of our example is 50, the base 
current must be adjusted for 20>A. This will allow 
an input signal for linear amplification to produce a 
base current variation of +20,uA, giving a collector 
current variation of almost ^lmA between satura- 
tion and cut-off (at upper and lower ends of the curve 
respectively). 

Correct choice of operating point is important; 
input and output impedances of a common emitter 
amplifier stage vary with collector current and so 
performance depends on the value of the (I.e. col- 
lector current. 

Bias Stabilisation 

To set the operating point, a simple method is lo 
arrange that a d.c. base current flows which (when 
multiplied by the current gain of the particular tran- 
sistor) gives the required value of collector current. 
A resistor from the negative supply to the base pro- 
vides this, but is not really effective, because of col- 
lector leakage current and variation with tempera- 
ture change. For stable operation, bias stabilisation 
is required, and the two circuits of Fig. 12 are 
methods of ensuring this. 





(a) (b) 

Fig. 12(a) : Base bias current feedback and (b) voltage bias. 

In Fig. 12(a) a resistor R B is coupled back from 
collector to base so that if the collector current in- 
creases, collector voltage falls and this fall is reflected 
back to base via R B , reducing base current. This 
tends to reduce collector current and oppose the 
change. However, this method does not allow con- 
trol with zero base current and slight variations be- 
tween transistors do not allow replacements to be 
made without reconsideration of the value of R B . 
A further point is that a.c. negative feedback is 
introduced by this method, and this may not be 
wanted. Splitting the bias resistor and bypassing the 
centre point to chassis with a suitable capacitor can 
reduce this feedback. 

A better method is shown in Fig. 12(b). The bias 
voltage V b applied to the base is obtained from a 
potentiometer Rl and R2 across the supply. A 
further resistor R h is put in the emitter circuit. The 
voltage across R E is equal to V,, less the voltage 
dropped across the emitter-base junction of the tran- 
sistor. If V b is made large with respect to this junc- 
tion voltage, the emitter current will depend only on 
V b and R E . Thus if V b is held constant, I E and there- 
fore I c will be independent of temperature and tran- 
sistor gain. 

A comparatively low value of R2 will not cause a 
significant change in V b . Actual values can be seen in 

712 



later circuits, and it will be noted that Rl is four or 
five times the value of R2. R E depends on the tran- 
sistor to be employed, and it will usually be bypassed 
by a large value capacitor (C, shown dotted) to avoid 
loss of gain with an a.c. signal. 

Practical Circuits 

Two low frequency amplifier circuits using this 
method of base bias stabilisation are depicted in 
Fig. 13. In the first, transformer coupling is used 
between stages, and in the second RC coupling is 
employed (note the polarity of the electrolytic 
coupling capacitors: in p.n.p. transistor circuits the 
succeeding base will generally be positive with res- 
pect to the preceding collector). Because a more pre- 
cise impedance match between stages can be made 
with a transformer, and thus the greatest energy 
transfer effected, this type of coupling is widely used. 




+ve 



(a) 




(b) 

Fig. 13: Circuits demonstrating base bias voltage stabilisation, 
(a) transformer coupling and (6) RC coupling. 

As with valve-cperated receivers intermediate fre- 
quency stages use transformer coupling, with the 
windings tuned to the appropriate frequency, as we 
shall see later. But for audiofrequency purposes 
coupling transformers are not so economical as 
resistor-capacitor combinations, and some efficiency 
is sacrificed to save costs. 

Having laid the ground and, it is hoped, taken 
some of the fearsomeness from formulae, we shall 
proceed to a breakdown of some of the circuitry 
likely to be met in radio and audio gear, with a few 
notes on constructing both the simple circuits them- 
selves in practical form and test devices that can 
help us handle transistors with more confidence. 

TO BE CONTINUED 



We regret that, due to shortage of 
space, several regular features have 
had to be held over. These will be 
resumed as soon as possible. 



everyday 
electronics 




DEC71 
15p 



NO. 2 Out Friday, November 19 



oncurr awtoNB 

mMhDCCK 

FOR THE EEGOMSR 
AMD THE 



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'FUZZ' BOX 

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Are you apt to experiment . . . this circuit-building desk has 

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ALSO— TEACH-IN ... A beginner's series dealing with the 

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713 



TECHNICAL 
TRAINING 

in radio television 
and electronics 



Whether you are a newcomer to radio and elec- 
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Transistor Portable available as separate course. 



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POWER UNITS 

These 400c/s l/P transistorised P.U. are sold for breakdown 
and contain the fo lowing modern parts, Transistors 8 type 
CV7061 these are Texas 2S012A Silicon N.P.N, type Vc 70v 
Ic 2 amps good to 2 Mc/s, 18 type ZR22 diodes rated 200 P.I.V. 
8 amps each, 18 tyae ZR12 diodes rated 200 P.I.V. 1-5 amps 
each, also Ledex Swt, conds, res etc modern guided missile 
equip. Supplied New crated. Price £4 50 plus 75p carr. 

AMPLIFIER UNITS 

Small self contained unit 11 5v 50c/s l/P uses valves 6X4, 12AX7, 
6AK6, these units are low impedance l/P 500 ohm ct and 500 
ohm O/P will match low res phones, fully enclosed in case 
size 10 x 3i x 3y filed V.C. Supplied with clrc and mods for 
240v mains also c re mods for speaker use and mods for 
transistor l/P. Well made unit ex USAF surplus. Ideal unit for 
beginner as these are self cpntained and will work in present 
form with H/phones, good condition. 

Price £1-50 plus 30p post. 

METER UNITS 

These are a 270 Dej meter with a F.S.D. of 1 Ma, scale marked 
0, 2, 4, 6, 8 x 100 Dea Cent white letters on black, size 2" O.S.O. 
3i" long, high grace meter made by Weston for Aircraft use 
supplied new boxed. Price £1-25 plus 15p post. 

Also still available Radio Alt 1-5 or 6 5 Ma F.S.D. 270 deg 
2?" dia at 95p pos: paid. 

RX/IND APN-9 

Comprises Rx section swt tuned 1 -8 to 2 Mc/s in 4 channels, 
Ind with tube 3BP1 3" green screen ideal for scope use, also 
the following valves are fitted 6SN7x13, 6SL7x3, 6H6x7, 5Y3, 
6SK7x3. 6SJ7X2, BSA7, VR105, 6Y6G, 2X2, 6N7, also 100 Kc 
crystal unit, large number ol other high grade parts. Supplied 
with Magnifier, Visor, Inst Book, Circ. American manufacture. 
Supplied new boxed. Price £8-00 plus 75p carr. 

MAINS TRANS. 

Pria 200/220/240v 50c/s Sec 500-0-500v at 400 Ma or can be 
connected to give 1 Kv at 200 Ma, varnish finish tag connec- 
tions, size overall bi x 54 x 4%. Supplied new ex service. 

Price £2-25 plus 40p post. 

400c/s INVERTORS 

l/P 23 to 28v D.C. O/P 115v 400c/s 1 phase at 180 Va sine wave 
O/P, all Transistoi unit uses 14 transistors, size 9 x 10 x 3" 
made by A. C. Cossor for M.O.D. Supplied new unused. 

Price £12 plus 50p carr. 



MISC. ITEMS 

Solartron Stab P.U. 200/250v l/P, O/Ps 250 or 300v at 200 Ma 
also 6-3v 4a twice, 6-3 1a supplied tested, £4-50. Selector 
Unit with 1 Ma 2±" sq meter 24v motor driving into gearbox 
with selector swt 13 24v relays in case with other parts £2 60. 
U.H.F. Rx unit tunes 330 to 335 Mc/s requires ext L.0. 24v l/P 
part of Aircraft landing Aid £3. Transistors OC42 type suit- 
able swt, flip flop etc i" leads 12 for 50p. Modulator unit 
part of BC640 T> supplied less valves as mod trans and 
230v fll trans 19" rack unit £3. Rx unit Marconi ADF Rx 
tunes 190Kc to 2 Mc/s in 4 bands remote tuned Rx as BFO 
and crystal filter l/P 24v or 12v and 250v HT ideal top band 
or car radio as O/P for spk. £6-50. Valves 6SN7, 6SL7, 
6SK7 6H6 all 5 for 50p. American 73 Radio Mags new back 
issues 8 for £1-15. Test Unit with 2x LA2503 Vinkors 4 Sil 
transis 4 min relays etc new 85p. Relays 12v 180 ohm 4p c/o 
sealed ex new equip 50p. Mod Kits contains 8 group boards 
with approx 130 parts new boxed 80p. Miniature plug and 
sk with clamp anci cover 18 way 15p. W.F. Gen unit contains 
24 B7g valves 24v blower etc sold for breakdown in case £2. 
RF26 tuning units 50 to 65 Mc/s 7 Mc/s I.F. O/P with circ 
new boxed £2-50. I.F. unit for use with 26 unit £2-25. L.T. 
chokes C. Core :>5H 1 amp 70p. Bridge Rect 12v 3 amp 55p. 
Panel fuse holders take 1±" fuses new 3 for 40p. Mains 
Voltage stabilisers 200/250v l/P O/P 240 at 200 Va. Tran- 
sistorised 19" rack mounting new with circ £12-75. 



All above prices include post or carr. All goods ex equipment 
unless stated otherwise. S.A.E. with enquiry 

A. H. SUPPLIES 

57 MAIN ROAD, SHEFFIELD S9 5HL 



714 




F.CJUDD 



The Modular Audio Mixing System is designed 
to allow any combination of signals to be mixed. 
The previous two parts have described some of 
the preamp. circuits and this final part concludes 
these and describes the final mixing and level 
monitoring arrangement 

MICROPHONE PREAMP (MIC Hi ZT) • 

This circuit shown in Fig. 19 is for microphones 
with built-in transformers or can be used with a 
microphone transformer at the input. The input 
impedance is about lOOkH and is suitable for micro- 
phone transformer secondaries, usually classified as 
medium to high impedance. The amplifier is a direct 
coupled BC109 pair with d.c. stabilization and 
negative feedback between the output and the 
emitter of Trl to set the gain. The circuit board lay- 
out is given in Fig. 20. 

PREAMP FOR CRYSTAL PICK-UPS 

The requirements are a high input impedance and 
a sensitivity between 500mV and IV r.m.s. The large 



WWr 







i£ri 



Jack or phono socket 

must be insulated from panel 




Com -ve 



Fig. 20 : Layout for the circuit shown in Fig. 19. 

R3 
150k 



muui • . \ ■■VI / 



Input 




470 k 




Output to 

line ani(/ 

or tone 

control 

/amp 

lOk$*y^AAr* 

loq5 /R10 

|/ 22k. 

R9 

B3 



Com. -ve 
v/S///, 
Fig. 19 . Circuit of the preamplifier for use with microphones with 
built-in transformers. 




Com -ve 
Fig. 21 : Preamp. circuit for use with high output crystal pickups. 

value series resistor and emitter follower input pro- 
vide the high impedance input and the gain, and 
therefore input sensitivity, is set by negative feed- 
back from the amplifier (Tr2) output to the circuit 
input. The nominal input sensitivity is 850mV. The 
output network VR1 and RIO is again as common to 
all the preamplifiers. The circuit board layout is 
given in Fig. 22. 

PREAMPLIFIER FOR GUITAR (G) 

Some guitar pick-up units have a high output and 

715 



rJCH 



Jack or phono socket 

must be insulated from panel 




Com. -ve 



Fig. 22: Layout for the crystal pickup preamplifier. 




?%%%■. 



Com. — ve 



Fig. 23: The preamplifier circuit for use with low output guitar pickups. 



Jifti 



Jack or phono socket 

must be insulated from panel 



+18V 




Com. -ve 



Fig. 24 : The component layout for the guitar pickup preamplifier. 

these could be connected to a line level input which, 
in conjunction with the line amplifier, has an input 
sensitivity of approximately 200mV. Low output, 
medium impedance guitar pick-ups may provide 
signal levels from around 20mV to perhaps lOOmV 
and require some amplification. The circuit given in 
Fig. 23 is quite a conventional arrangement originally 
due to Mullards and has provision for setting the 

716 



ir components list 





ic Pre-amp (Mic 

Tri,Tr2 BC109 

VR1 10ka Carbon iog. pot. 



Resistors 



R1 220k£ v : R5 22QkU J* 

R2 680Q / R6 ibkQ Sy 

R3 VfSl v R7 22kO S y 

R4 39kfi S R8 390k(} • 

All iW, 10% types 



Capacitors 

C1 1 -5uF 






C2 
C3 



2-5^F 
10Gpl : 



25V 
25V 



C6 



1«prV 25 V 



Crystal p.it. Pre-amp (P.U. Xta!) 

Tr1,Tr2 BC509 

VR1 lOkii Carbon log pot. 



Resistors 










R1 470k£> 


R5 


1 -Skfi 


R9 


820H 


R2 120W! 


R6 


120kS2 


R10 


22kO 


R3 150ftf! 


R7 


12kO 






R4 100kl! 


R8 


mm 






Al 


iW, 10% typos 






Capacitors 










C1 0-1p.F 




C4 


100mF 


25V 


C2 01/iF 




C5 


VF 


25V 


C3 25**F 


25V 









Guitar Pre-amp 

Tr1, Tr2 BC109 

VR1 10fcQ Carbon log. pot. 

PR1 1Gk& Carbon preset 



Resistors 

ri nmi 

R2 4-7Wi: 

R3 12kjQ 



Capacitors 

; ci Q-ifiT \ 

C2 10(fc*F 

C3 200oF 



R4 100£2 R7 

R5 1-2kll R8 

R6 58012 R9 
Al! iW, 10% types 



2-2kft 

22kQ 

150kl2 



25 V 



€4 
C5 



100>F 2a V 
2-5ftF 25V 



.ine Input 

VR1 10kQ carb 
R1 22RO(iW, 10°/ 



>ot. 



VU Meter 

Type V403 



Henry's Radio 
jack or phone sockets as required. 



overall gain from about 12 to 40dB. This is controlled 
by PR1 which sets the amount of negative feedback 
between Tr2 collector and Trl emitter. With PR1 at 
maximum resistance the gain will be at 12 to 13dB 
and about 40dB with PR1 at minimum. The input 
impedance is typically lOOkft and suitable for the 
majority of medium to high impedance guitar pick- 
ups. PR1 should, be adjusted so as to provide not 
more than the requisite lOOmV or so output between 
R8 and earth with VR1 at maximum. The circuit 
board layout is given in Fig. 24. 



LINE LEVEL SIGNAL INPUTS 

Line level usually refers to signals of over 100m V 
or so which are linear i.e., requiring no equalization 
and no preamplification other than that necessary to 
bring the level to the requirements of the system 
output, in this case to a uniform IV r.m.s. As no pre- 
amplifier is required, line level signals, such as from 
a radio tuner, tape recorder external amplifier out- 
put, etc., could be coupled directly to the line 
amplifier but as the outputs from other sources i.e., 
preamplifiers and/or other line inputs are also to be 
connected, the passive mixing component must be 
included to prevent any one signal source loading the 
others. Line level inputs are therefore connected to 
the line amolifier via a gain control and series 
resistor (22kfl) in the same way as the output from 
each preamplifier is connected. This method is 
commonly used in signal mixing circuits so that any 
one signal source can be controlled independently of 
any other. The series passive component has been 
made high (22kfi) compared with the gain controls, 
each of which are lOkfl. The insertion loss is a little 
higher but the higher value series resistor ensures 
complete fadeout of the signal when a gain control is 
at minimum and that no loading is imposed on other 
mixing circuits. The circuit for the line inputs, as 



Input jack or 
phono socket 



rJiS 



VR1 
10k 
log 



Input to 

line amp 

or tone 

control 

amp 

>■+—> WVW— »• 



22k 



Vft77>. 



Com -ve 




Line amplifier output 

C6 R 

-»-{]| t VWW-frl 



From line amp 
output C6 



680 



5k 



VU meter full 

scale deflection 

for approx 600mV 

audio signal 




-^/VWv-*2 



-V«M/V^3 



vv///. 



k -\\VvV*or more 



Com. -ve 



Fig. 25 : The resistive arrangement for the line inputs. 



Fig. 26. (left) The VU meter arrangement. 
Fig. 27 : (right) The arrangement for feeding more than one amplifier. 

discotheque or music amplification systems. The high 
signal output of around IV r.m.s. is sufficient to 
directly drive many power amplifier modules now 
available so in fact a complete multi-channel 
amplifier system is perfectly feasible. The various 
combinations given in the block diagram in Part 1 
are but a few of the possibilities and any combination 
can be extended for stereo operation simply by 
duplication. For stereo mixing systems ganged gain 
and tone controls are not necessary, in fact separate 
controls are advisable, as they allow much more 
control over stereo balance. The output from the line 
amplifier can be coupled to more than one amplifier 
or tape recorder simultaneously or for example to a 
tape recorder and an amplifier for simultaneous 
recording and monitoring. As the input impedance 
of external equipment may vary, external equipment 
connections should be made via series resistors as 
shown in Fig. 27. Normally each resistor can be 
47kft but this may be reduced to as little 
as lOkfl if the higher value reduces the output signal 
too much as it may do if external equipment has a 
very low input impedance. 



shown in Fig. 25 consists simply of the gain control 
and series resistor. Up to half a dozen line inputs can 
be used but more than this number could cause 
loading. If say, four or five preamplifiers were used, 
then the number of line inputs should be limited to 
three or four. Much the same applies to the total 
number of preamplifiers e.g., six should be about the 
limit with two line inputs. 

VU LEVEL METERS 

VU meters with built-in rectifiers are readily avail- 
able and most of these will read well over full scale 
with a IV r.m.s. signal. This allows a VU meter to be 
connected across the line amplifier output with a 
series variable resistor so that the meter can be 
adjusted for a maximum signal indication of IV 
r.m.s. equals OdB. The meter could also be adjusted 
to read in conjunction with a tape recorder level 
meter in cases where the mixer is remote from the 
recorder. The connection is simple enough as shown 
in Fig. 26 but note that the meter must be one with a 
built-in rectifier and provide full scale deflection for 
at least 600mV of signal. 

GENERAL APPLICATIONS 

As already mentioned in Part 1, the various pre- 
amplifiers, tone control unit and line amplifier can 
be connected together to provide signal mixing 
facilities for sound recording, public address and 



LAYOUT IN CABINETS 

The photos shown in the previous parts are of a 
small mixing system which would be ideal for tape 
recording enthusiasts and, as can be seen, each of the 
preamplifiers are simply mounted side by side. The 
built-in screens prevent crosstalk and shield the 
boards from hum pick-up. Nevertheless a metal 
cabinet should be used for any system derived from 
the various modules. The mains power supply should 
be situated away from the preamps and preferably 
in a screened compartment. ■ 



Hell 



Jack or phono socket 

must be Insulated from panel 



+18V 




Com. -ve 



Last month's Fig. 12 (page 619) showed the incorrect layout. The 
correct layout for the crystal mlc. preamp. circuit is shown above. 

717 




F. C.JUDD 



ffl 






\\ 




i 




c. t^- 


'■ — ~^ 


i l\ 



THE completed keyboard is mounted in a tilted 
position as in Fig. 9b on a hardboard base that 
fits into the top of the organ. This base also 
carries the circuit board and battery etc. The piece of 
hardboard is cut as in Fig. 9a and the keyboard 
mounted as in Fig. 9b so that the keys themselves are 



fW 



J— 




^t 



Mjfr- 




Key baseboard 



Vg xl /2 p all beneath rear edge 
of keyboard (glued) 




Top Iniide of case 



Fig. 9: Details of the keyboard mounting. 






Upper front panel V\ deep made from '' a hardboard 

(secure panel sc Wat lower edges of Keys are about '-g above top of panel) 

Fig. 10: A front view of the keyboard mounting and the siting of the 
upper front panel. 

level. It is important that when the completed key- 
board is fitted in the top of the case that the front of 
the keys are aligned with the top of the upper front 
panel as shown in Fig. 9c and also in Fig. 10 so that 
when a key is depressed the top does not come 
below the upper edge of the panel. When the key- 
board has been correctly aligned it can be secured in 
the organ cabinet. 

The lid of the organ is made up as shown in Fig. 11 
and in the photo. Appropriate dimensions for the lid 
are best derived from the inside measurements of 
the top of the case and the height of the keys but 
the lid must be made so that the centre portion 
drops directly behind the black keys. The whole of 
the lid is hinged on the rail at the rear of the 
cabinet. Figure 11 also shows more detail concerned 
with the expression pedal system. Ensure that when 
the lid is closed down it does not foul the. keys and 
that all the keys can be depressed and will return 
to their rest position. 

At this stage the painting might well be done but 
first the keyboard and the main front panel should 
be removed. If a music stand is to be included this 
should be fitted and can be made from a piece of 
hardboard about 12 x 7in. attached to the lid by a 



718 



WIIWill IIIIWHH"! 



3/ a plywood 



Upper front panel 



Fig. 11: The lid construction 
and a cut-away view of the 
expression pedal. 




t- 



Stop block for pedal' 

short length of 4 x ^in. batten. The original organ 
was finished with a bright red gloss paint over an 
undercoat of emulsion paint. 

When the decor is complete the loudspeaker can 
be installed and the expression pedal (if used) 
adjusted. The on/off, vibrato and voice switches can 
be fitted to the left hand portion of the lid and a 
back cover made up of hardboard to close in the 
rear of the organ. Two small wood blocks should be 
fitted inside, one either side of the keyboard, and 
flush with the upper front panel. These act as stops 
when the lid is closed down and take a screw through 
each side of the lid so that it can be secured against 
opening by small hands. These blocks are just visible 
in the photograph. 

The component board is mounted just behind the 
key contact frame as shown last month — and 
allows for convenient short connections between the 
tuning pre-sets and the key contact wires. A rear 
view of the completed organ with the circuit board 
in position is shown. 

TUNING 

First adjust all the pre-sets, including PR1, to 
midway travel and set SI, the vibrato switch, and 
S2, the voice switch, so that both are open. Tuning 
is best done with a piano and should be commenced 
with the pre-set for the F key (No. 25) at midway. 
Now tune the F note to pitch at 698 -4H? with PR1, 
the initial pitch control. The remainder of the pre- 
sets from E No. 24 down to F No. 1 at 174 -6Hz can 
now all be tuned one after the other. 

The vibrato should produce a pleasant pitch varia- 
tion, not too pronounced, at about 6 to 8Hz. The 
intensity of the vibrato can be increased by reducing 
R14 to lOOkft or decreased by making R14 about 
150kfl. The vibrato frequency can be altered by 
slightly increasing or decreasing the value of R2. 
With the voice switch S2 closed, the tone should be 
flutelike and somewhat softer. 

The expression pedal will reduce the sound level 
somewhat but if moved up and down quickly whilst 




A rear view of the completed project with the back removed. 

a note is sustained will produce a pronounced "wah- 
wah" effect which will no doubt intrigue the junior 
player. 

The organ will stay in good tune for a long time, 
or until the battery voltage falls and the two octave 
range allows for the playing of a wide range of tunes. 
Like the author's grandson who has become the final 
owner of the prototype, any youngster will get a 
great deal of enjoyment from it. 



In the circuit of the 2-octave miniature 
organ published last month (Fig. 1, 
page 594) there is an error in the multi- 
vibrator circuit. C6 should connect 
between the collector of Tr2 and the 
base of Tr3 and not between the bases 
as shown. In Fig. 2 the resistor next to 
R1 should read R14 and not R13 as 
shown. ■ 



719 






DIGITAL FREQUENCY COUNTER/TIMER 




PART 4 (continued from the November issue) 



Frequency measurement is the primary purpose of 
the instrument and although, on low and medium 
frequency signals of a reasonable amplitude, it is 
sufficient to connect the signal and read away, better 
results may be obtained particularly on the higher 
frequencies if the controls are set correctly. 

It should be remembered that the purpose of the 
input clipping stage is to provide, from the input 
signal, a clean squarewave suitable for driving the 
signal gate and decade counters. 

With the input switch in the "AC" position the 
input a.c. signal can be "slid up and down" the 
input characteristic of Trl by rotating the LEVEL 
control, so that symmetrical clipping takes place. 

The smaller the input signal and the higher the 
input frequency the more important it is to set the 
LEVEL control correctly. 

With the signal applied to the input and the 
function control set to a low frequency range, the 
LEVEL control should be carefully rotated from 
one end to the other and the range noted over 
which a steady reading is obtained. The correct 
setting is in the centre of this range (see Fig. 19). 

The actual physical position of the control depends 
to a large extent on the individual characteristics of 
Trl. (It may be possible to substitute other types 
of f.e.t. in place of the 2N3823 but the spread of 
characteristics may make the LEVEL control in- 
operative.) 

It is assumed that normally the signal to be 
measured will be clean and free from hum and noise. 
However, if a large amount of hum (mains ripple) 
is present on the signal to be measured this may 
cause errors due to the clipper stage being saturated 
for periods of the hum waveform, as shown in 
Fig. 20. 

A solution to this problem is to use a simple high 
pass filter, as shown, which will effectively remove 
the low frequencies whilst allowing the r.f . signal to 
pass through. 

720 



J.TH0nimiN-LAWRENCE GW3JGA 



Assuming that the LEVEL control has been set 
to its optimum position, the function switch should 
then be rotated to a position where the first digit 
of the displayed reading appears on the left hand 
tube. 

Suppose that a signal of 7 054321MHz is being 
measured, the reading of frequency should be 
7 • 054MHz. Setting the function switch to the highest 
frequency range will cause a reading of 07-05MHz 
to be displayed and obviously the frequency is not 
being measured as accurately as it can be. 

Conversely, by moving the function switch the 
other way to a lower frequency range, the 7 dis- 
appears off to the left and a reading of 0543 is dis- 
played. 

This procedure may be repeated until in the Hz 
position the reading will be 4321, the right hand 
figure indicating cycles per second and the left 
hand figure indicating kHz. 



|DK 06091 



Signal, 
input 



Clipper 
output 



ipper 'window— 




Incorrsct setting 
of level control 



uuir 

Correct setting 
of level control 



Fig. 19 : Waveforms showing correct and incorrect settings of the 
LEVEL control. 



SD33 




To 
inter 



*T 



Input 



IHF.C 



- _a]V~ i/u_ 



High-pass 
filter 



Fig. 20 : Effects of hum and noise on the input signal. A simple high 
pass plter is shown on the right. 



This is a useful facility for measuring small 
changes in frequency, e.g. checking variable fre- 
quency oscillators, frequency modulation systems, 
and monitoring the frequency of a signal generator 
when aligning the i.f. stages of a receiver and check- 
ing crystal filters. 

It is important to remember that whilst this 
measurement gives very high discrimination it is 
only a relative measurement of frequency and is 
not an absolute measurement to this accuracy. The 
stability of the internal crystal oscillator is insuf- 
ficient for this to be so. 



Calibration Outputs 



The 100kHz, 10kHz and 1kHz outputs at the rear 
of the instrument may be used for calibrating 
receivers. This can be done by loosely coupling the 
appropriate output to the input of the receiver. A 
series coupling capacitor and resistor of about 
l,000pF in series with lkfl should be used as each 
output is directly connected to the divider circuits 
and an accidental short to earth or worse still to a 
high voltage would upset the operation of the divider 
and may cause permanent damage. 



Time and Period Measurement 

The simplest time measurement for the instru- 
ment to make is in measuring the time of one cycle 
of a repetitive waveform. This is useful for fre- 
quencies below 100Hz as greater accuracy can be 
obtained. 

On the time ranges of the instrument, the count- 
ing is initiated by the negative going part of a 
signal and stopped by the next negative going signal. 
The operation on various waveforms is shown in 
Fig. 21a, b and c. 




IDI osii! 



&■«- t — — *4 

Sine wave Input 



N t — — rt 

Square wave input 



Input to 




Pulse input 



Push button circuit 



Fig. 21 : Operation of various timing waveforms. Circuit on the right 
provides a fast negative going pulse when S1 is closed. 



For the timing of events, as an electronic stop 
watch, it is necessary to provide a circuit which will 
generate a fast negative going pulse when a button 
is pressed. A suitable circuit is shown in Fig. 21d. 

The 1,"F capacitor CI is normally charged to 
+ 5volts through Rl. When the microswitch is 
pressed a sharp negative going voltage step is pro- 



duced which starts the timer counting time. Tht 
switch is released and Rl recharges CI. When the 
switch is pressed for the second time the negative 
pulse stops the count and the total time between 
the two operations is displayed in mS or seconds 
depending on the setting of the function switch. The 
purpose of CI is to prevent the contact bounce in 
SI from causing false triggering of the instrument. 
For automatic operation, two photocells may be 
used and a suitable circuit for timing the duration 
between two events is shown in Fig. 22. 




Fig. 22 : Circuit shown above is suitable for automatically timing the 
duration between two events. 



An extension of this system with more powerful 
light sources may be used for race timing, horse 
trial events, etc. 

In the above applications of start-stop pulses it is 
suggested that the input switch is set to the "AC" 
position and that the LEVEL control is adjusted 
to the position which gives reliable operation, this 
is usually slightly higher (clockwise) than the centre 
operating point used in frequency measurements. 



Very Low Frequency Input Signals 

For very low frequency signals where the input 
coupling capacitor may attenuate the signal severely 
the input switch may be used in the "DC" position. 
This may result in the LEVEL control having little 
or no effect. However, if the input signal has an 
amplitude of about 10 volts peak to peak about 
earth potential, reliable operation of the instrument 
should be obtained. 

The integrated circuits used in the Digital Fre- 
quency Counter Timer are the 74 series of TTL 
(Transistor-Transistor Logic) in the 14 and 16 pin 
DDL (dual in line) package. The device operates 
from a supply of +5 volts (4-5V min., 5-5V max.). 

721 



In the operation of the logic only two states are 
possible, and 1. 

logic = "low" =less than +0-8volts. 
logic l = "high" = greater than +2-0volts. 



7400 N Quadruple 2 Input Nand 
Gate 

This device contains four separate identical two 
input NAND (NOT AND) gates, as shown in Fig. 23. 



Truth table 



2 Input NAND gate 

Inputl TN 

f>— Output 

Input 2 — J 



Input 1 


Input 2 


Output 


Low 


Low 


High 


High 


Low 


High 


Low 


High 


High 


High 


High 


Low 



V CC 


84 A4 X4 B3 

m 


■ A3 


X3 






d 






I 


__ 


£> 


J 


^ 






r\ 


OON 


B> 


— 




[ 


- 


9>~\ 




■=! 







iiJ Lit LU LU LU LU LIT 

Al B1 XI A2 82 X2 



Fig. 23. SN7400N integrated circuit and truth table. 

Each gate has two inputs and one output and the 
operation is shown in the truth table. It can be seen 
that only when input 1 AND input 2 are high will 
the output NOT be high, i.e. low. In the circuit of 
the instrument some gates are shown with only one 
input and here the other input is left disconnected. 
This is equivalent to connecting it to a high input. 
In this condition the gate becomes an invertor, the 
output condition is the inverse of the input. 

7473 N Dual Master-Slave J.K. 
Flip Flops 

The SN7473N contains two Master-Slave J.K. Flip 
Flops, each flip flop contains a large number of 
gates all internally connected to form a bi-stable 
or flip-flop in which the state of the outputs for 
specific input conditions is clearly defined. This is 
shown in the truth table in Fig. 24. What this means 
is that if J and K are both low, no change takes 
place during the clock pulse. But if K is high and 
J is low the clock pulse will cause Q to go low and 
conversely if J is high and K is low the clock pulse 
will cause Q to go high. And finally if J and K are 
both high Q will change state at each appearance 
of the clock pulse. With J and K both high the 
circuit makes a divide by two divider stage, the 
output from Q being half the frequency applied to 
CP. 

722 



Master -slavs 
J K flip flop 



J 

♦CP 
K 



Q«': 



CP - Clock pulse input 
C - Clear 




V 



Clock input waveform 



Truth table 




tn 


t n +1 




J 


K 


O 




Low 


Low 


On 




Low 


High 


Low 




High 


Low 


High 




High 


High 


On 


t n a bit time before clock pulse 

t n +1 - bit time after clock pulse 








|M0!H|- 




Q1 

M 



E 



Q1 Common K2 02 C2 



Q 



s 

:iear 1 

J Cloc< K 



? 



Q Q 
2 Clearh 

K Clock J 



SN7473N 



LU, r HJ LU LU LU LU itJ 

Clock 1 Clean K1 Vcc Clock 2 Clear 2 J2 

Low input to clear sets Q to logical 'O' regardless of clock state 

Fig. 24 : SN7473N integrated circuit and truth table. The sequence of 
operation relative to the clock waveform is also shown. 



In the master-slave JK flip flop, the input to the 
master section is controlled by gates operated by 
the clock pulse. The clock pulse also regulates the 
state of more gates which connect the master and 
slave sections. The sequence of operation, relative 
to the clock waver'orm shown in Fig. 24, is as follows : 

1. Isolate slave from master. 

2. Enter JK input information into master. 

3. Disable input gates. 

4. Transfer information from master to slave. 
The input C is a direct clear input which restores 

Q to low irrespective of any other input signals., 

opposite logic condition to Q. 

instrument is in storing information and transferring 

this on the application of a pulse to the clock pulse 
Q is the reciprocal of Q and always has the 
The use of the Master-Slave JK Flip Flop in the 

input. 



7490N Decade Counter 

The SN7490N contains 4 flip-flops and 3 gates 
forming a divide by 2 stage and a divide by 5 stage. 

When used as a binary coded decimal counter, 
the signal input goes to the divide by 2 stage and 
from the output of this to the divide by 5 stage. 
The binary coded decimal output is then available 
as shown in Fig. 25. 

When used as a frequency divider, as in the Crystal 
Oscillator divider panel, it is more convenient to 
feed the signal into the divide by 5 stage tirst and 
then the divide by 2 stage, this ensures a 1 : 1 square 
wave output which has certain advantages when 
used as a calibrator output. The other arrangement 



input AD B ■ C 

rJLa n n a n n 



T. _ _ i 

|. yuu-uuuu 



SN7400N connected ?or 
binary coded decimal 
counting 




a 

mm 

Out 



SN7490N connected for 
decimal division and 
square wave output 



jr H :5 r V 



Clock Output Output Output 

input A NC A . Common 8 

h .r?ii . fjj] ri m [ii 





vqc Reset Reset 
-9' '«' 

Fig. 25 . SN7490N integrated circuit used as a binary coded decimal 
counter. 

will of course also divide by 10 but the output wave- 
form is far from symmetrical. The SN7490N has 
input connections for resetting to "9" or "0" and 
in the instrument only the reset to "0" is used. 

74141 N B.C.D. to Decimal 
Decoder Driver 

This device contains a complex arrangement of 
gates terminating in ten high voltage transistors 
for driving the numeral indicator tube. The opera- 
tion of this device was illustrated in Part II of this 
series (Fig. 9, page 480, October 1971 issue). 

A number of queries have been received regard- 
ing the use of a SN7441AN device in place of the 
SN74141N. The SN7441AN was in fact used in the 
prototype and whilst a number of these functioned 
satisfactorily a few gave trouble by loading the 
decade counter excessively and causing an incorrect 
count. 

The SN74141N is an improved version of the 
original SN7441AN. ■ 



B.B.C. RADIO LONDON 

Sunday, November 7th at 3 p.m. 
on 95-3 MHz. 

"Don't call us 'hams'!" 

featuring radio amateurs of London, with 

Sylvia Margolis, past P.R.O. of the 

Radio Society of Great Britain 




CHARLES MOLLOY 

edium 

bve Column 



ONE of the attractions of medium wave DXing 
is its unpredictability, a feature which is very- 
apparent when the listener searches for North 
American DX. Although reception conditions can 
vary considerably from night to night, there is also 
a long term trend which follows the sunspot cycle; 
the best medium wave DX occurring in years of low 
sunspot activity. We are now well past the maximum 
of the current sunspot cycle and can expect an all- 
round improvement in long range reception on m.w. 

Last month it was suggested that the newcomer 
to MW DXing should listen on 1070kHz after 2300hrs 
for the Canadian CBA located at Moncton, New 
Brunswick. Other North Americans that are fre- 
quently heard in this country during the early part 
of the night are CNB 640kHz in St. John's, Newfound- 
land; WNBC 660kHz in New York City; WABC 770 
also in NYC; WHDH 850 in Boston; CBH 860 in Hali- 
fax, Nova Scotia; WABI 910 in Bangor, Maine; CJCH 
920 Halifax, N.S.; CJON 930 St. John's; CHER 950 
Sydney, N.S.; WINS 1010 NYC; WBZ 1030 Boston; 
WBT 1010 Charlotte, North Carolina. An unusual 
catch is Radio St. Pierre 1375kHz situated at St. 
Pierre, the capital of the French islands of St. Pierre 
et Miquelon, located to the south of Newfoundland. 
When conditions are favourable R. St. Pierre will 
cause a heterodyne on Lille 1376kHz before the 
latter closes down for the night at 2300hrs. 

Harold Emblem, of Mirfield, Yorkshire, has re- 
ceived a verification from the new station at Kin- 
shasha (692kHz). This is a difficult country to verify 
and the address for reception reports is Chef des 
Services Techniques, Radiodiffusion Nationale Congo- 
laise, Kinshasha, Republique Democratique du Congo. 

Reception of Far Eastern medium wave stations 
is possible in the U.K. during the afternoon in 
winter time. Stations fade-in about one hour before 
sunset and are audible either until they sign-off or 
they become submerged in interference from Euro- 
peans, which increases as darkness approaches. The 
l,000kW All India Radio outlet at Calcutta, on 
1130kHz which broadcasts in English from 1530 until 
1600hrs was heard frequently last winter. It is easy 
to pass over this station as it suffers from slow cyclic 
fading, so it is worth while pausing on the frequency 
for a few minutes. The Voice of America, Okinawa 
1178kHz is another megawatter that is often heard 
in this country, usually as a background to the 
Swedish broadcaster on the same channel. Pro- 
grammes from Okinawa are in local languages but 
identification is on the hour and half hour usually 
in English and is accompanied by the Yankee Doodle 
signature tune. Sign-off is at 1700hrs. Peking has been 
logged on 1,000kHz, 1230kHz and 1290kHz; Taiwan 
(Formosa) has been heard on 750kHz and 1200kHz 
with programmes of westernised Chinese music while 
Kabul, Afghanistan 1280kHz is a regular until close 
down at 1830hrs. 

Reports to 132 Segars Lane, Southport PR8 3JG. 



723 



Ul 

II 



'6 > or ^Z >y 




MONTHLY 
NEWS FOR 



DURING the past few months I have received 
many letters asking the correct way of con- 
verting metres into kilohertz. It would appear 
that many readers have receivers which are calibra- 
ted in metres only. 

The conversion is performed as follows: In order 
to obtain the frequency in kHz divide 300,000 by the 
wavelength in metres. This formula also works in 
reverse, that is: wavelength in metres can be ob- 
tained by dividing 300,000 by the frequency in kHz. 

The first report this month comes from Paul Benton 
of Hednesford who has an Astrad-Nova receiver. 
Paul's aerial system consists of a 75 foot long-wire, a 
14-element television aerial and a copper grid. Items 
from his log include : 

4783 Radio Mali, in French at 2145. 

4800 Radio Lara, Venezuela, music at 2330. 

4900 R. Juventud, Venezuela, music at 0000. 

4900 R. Conakry, Guinea, news in French at 2300. 

4940 R. Abidjan, Ivory Coast, French at 2250. 

5015 Windward Islands B.S., English at 2345. 

5035 R. Bangui, Cent. Afr. Rep., English at 2045. 

5047 R. Lome, Togo, African music at 2100. 
11652 R. Pakistan, Karachi in English at 2030. 
11815 HCJB, Quito, Ecuador in English at 0040. 
11855 Saudi Arabia in English at 0430. 

Stephen John Mathews of Hull has a new receiver, 
the Trio 9R-59DS, but having broken his leg playing 
football he has to be content with his 90 foot loft 
aerial instead of the new one which he was going to 
erect. The combination yielded some interesting 
stations including : 

2326 S. African B.C. in English at 0030. 

4777 R.T. Gabonaise in French at 0000. 

4800 R. Lara, Venezuela in Spanish at 0400. 

4880 R. Universo, Venezuela, Spanish at 0045. 

4955 R. Nacional, Colombia in Spanish at 0315. 

5960 Voz de Angola in Portuguese at 2015. 
15170 ELWA, Liberia in French at 2020. 
15200 NBC, Lagos, Nigeria, English at 1830. 
15280 4VEH, Haiti in English from 2330 to 0200. 
15415 FEB A, Seychelles, testing at 1855. 
15485 R. Portugal Libre, clandestine at 1922. 

Peter Reed of Brighton has used his R1155N re- 
ceiver in conjunction with his Joystick antenna to log 
some interesting stations which include : 

3380 Malawi B.C. in English at 2000. 

4805 Voice of Kenya, Nairobi, 1800-1845. 

4875 R. La Cruz del Sur, Bolivia, Spanish at 1100. 

5040 R. Burma noted at 1445. 

9520 R. La Cronica, Peru, Eng. and Sp. at 1200. 
11825 Papeete, Tahiti in French at 0755. 
21685 Kuwait B.S. in Arabic at 1300-1330. 

Ross Pullen of Crawley has sent in a log which 
includes the following interesting stations : 

5970 R. EI Sol, Peru in Spanish at 0200. 

9670 Saudi Arabia in Arabic at 2215. 

724 



THE BROADCAST BANDS 

Malcolm Connah 



Frequencies in kHz • Times in GMT 



9725 R. Burma in English at 0700. 
11715 R. Republik Indonesia in English at 0900. 
11875 R. dif. Nacional, Nicaragua at 0200. 

Julian V. Moss of Rayleigh, Essex has just pur- 
chased a Meridian receiver and a 50 foot long-wire 
enabling him to hear: 

6050 HCJB, Quito, Ecuador in German at 0615. 

6080 R. Berlin Int. in French at 2100. 

7280 R. Berlin Int. in English at 2045. 

9530 AIR, Delhi in English at 2100. 

9550 R. Warsaw, Poland in English at 2030. 

9700 R. Sofia, Bulgaria in English at 1935. 

9765 Deutschewelle in English at 2150. 
11620 AIR, Delhi in English at 2030. 
11672 R. Pakistan, news in English at 1900. 
11700 R. Kiev, Ukraine in English at 1945. 
11740 R. Australia in English at 1610. 
11755 Finnish B.C. in English at 1000. 
11765 R. Australia in English at 0800. 
11800 RAI, Rome in English at 1940. 
11910 Radio Budapest in German at 2010. 

Fred Wall of Walthamstow, London E.17 used his 
homebrew 4-valve superhet and a 20 foot long-wire 
aerial to hear the following stations : 

7290 TWR, Monte Carlo at 1600. 

9555 Finnish B C. at 1815. 

9620 R. Belgrade, Yugoslavia, English at 1942. 
11745 HCJB, Quito, Ecuador at 0015. 
11765 R. Australia with news at 0900. 
11790 R. Afghav.istan, news in English at 1800. 
15345 Kuwait B.S. with news at 1830. 
17820 RSA, S. Africa with news at 1845. 
21640 NHK, Japan with music at 1518. 
25900 R. Norway in Eng. /Nor. at 1820. 

Robert C. Hanstock of Sheffield has a Colombia 
5-valve superhet and a 50 foot long-wire which en- 
abled him to hear : 

5980 RSA, S. Africa in English at 1815. 

7205 R. Australia in English at 1600. 

9010 R. Peking in English at 2045. 

9740 Radio Portugal in French at 0700. 
Robert also reports that Radio Nederland is to 
open a new relay station at Tananarive, Malagasy in 
November. Programmes will be beamed to Africa and 
S. Asia. The station will also be changing the frequen- 
cies of its evening transmission in English to Europe; 
the new frequencies being 17830, 6085 and 6020 from 
1830 to 1950. 

D. A. Hairon of St. Clement, Jersey is now using 
a 100 foot long- wire with his other equipment and 
reports hearing: 

9740 R. Cairo in English, 2245-2300. 
11730 R. Nederland, Bonaire in Eng. at 0630. 
11795 R. Nacional, Rio de Janeiro at 0055. 
11865 R. Clube, Brazil at 0200. 
21705 R. Mexico in Spanish at 2205. 

Reports should arrive by the 15th of the month 
and be addressed to me at 5 Ranelagh Gardens, 

Cranbrook, JJford, Essex. 



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725 




FIRST letter out of the hat this month is from 
Peter Short (ZS2HT). He remarks on comments 
made in an earlier Amateur Bands regarding 
ZS1MH. Peter says that the latter station has man- 
aged over 1,000 contacts on 3-5MHz notching up 115 
countries. Gear is a KW Atlanta and a G8KW antenna 
at 175ft. Apparently ZS1MH will be using a 66ft. 
loaded vertical early next year and has plans to have 
a 2-element beam for 3-5MHz up by next March. 
Peter says also that there is intense ZS activity on 
both 3-5 and 7MHz between 0400 and 0600 g.m.t. 
Listen 7090 to 7100kHz and from 3730kHz upwards. 

A shout from Des Walsh (EI5CD) of Co. Tipperary. 
He asks for s.w.l's who can QRX on 2 metres to listen 
out for his a.m./f.m. sigs on the following freqs. : 
144-7, 144-9, 145-35 and 145-96. Des runs 8W output 
to a 6-over-6 and is on most weekends beaming east- 
wards. 

The aerial is 67ft. wrapped neatly around a first 
floor flat in Cambridge. The receiver is a "modded" 
HRO-MX and the log from M. Wallace is for 3-5MHz 
s.s.b.; HA0KHT, WA80BG, ZB2CC, ZL3LE, ZL4JW. 

Listen after 0100 b.s.t. around 7-2MHz for KP4GL 
who m.c's the Caribbean net, advises Paul Edwards 
(Penge). Paul's antenna is 120ft. "bent round the 
garden" and the Rx is a homebrew 1-V-l. Log for 
7MHz reads; CN8HD, CT1GQ, CT2AK, EA7EU, 
FM7WN, K4UAS, KP4DHD, KP4GL, KZ5JF, PJ2CW, 
PY3APH, PY7BIH, VP7DL, W1YNQ, W2RGV, 
W3LTU, WA2BVU/4X, YV1BI, YV5BPG, ZL2BT, 
4Z4JT, 8P6AJ. 

John Brockett (Hemel Hempstead) has a homebrew 
transistor superhet which is working on 160 and 80 
metres. Best on 160 to date is GM3SVK/A in the 
Shetlands. On 80, John bagged many EUs plus 
JY9DX, OD5BA, VEIOW, VOIFG, 3V8ZK and 
5H3LV. 

Peter West (Leigh, Lanes), reckons midnight to 
0700 for 7MHz DX. Proof of the pudding comes from 
Peter's log for that band gained with the aid of a 
TCS-9 receiver and 132ft. end-fed (all s.s.b.); CM3LN, 
EA3LP, EA6BH, K4ELK, K4PTK, PY2ASY, PY7AJB, 
PZ1CV, W1EEF, W2BMK, W3WGH, W4CVS, YV4BE. 

Talk about UX logs, I gotta DX letter. Epistle from 
Karl Muller of Mbabane, Swaziland, uses a Philips 
domestic portable and the oscillating detector of a 
homebrew t.r.f.-as a b.f.o. Karl stalks 40 metres with 
this little lot and reports squeaks of activity from: 
CR7FM, CR7BN, DK2EQ, DJ9JF, EI8H, ET3ZU/A, 
G8NV (that's DX to Karl!), GM3JDR, HA3GR, 
HB9AGN, IT9FG, JA0BCO, JA1BK, JA2BUX, JA3LU, 
JA4IWD, JA5BLH/MM, JA6FT, JA7DCK, JA9YBA, 
JH1EDB, JW1EE, K4THA, K6DC, K6DV, KH6RS, 
LZ1KVV, OK2BM, OH5UQ, SM5EXE, thousands of 
"U" stations. 

David Lawley (Gravesend) CR100, a wide variety of 
antennas, has been doing a spot of all-band listening. 
Topband log includes; GI3ZIA, GM3WDF and 
GW3UMB. Up to 3-5MHz and a QRX revealed; 
CT1BT, EI3S, GC3MDX, OY7JD, PY7AF, VOIFX, 

726 



THE AMATEUR BANDS 

David Gibson, G3JDG 



Frequencies in kHz • Times in GMT 



VOIFG and YK1AA. On 40 metres, David's best were; 
OZ9HG (Langeland Island) and TI2IT. 

Without doubt the award for the best kept log of 
the year goes to Adrian Barnes of Abingdon, Berks. 
This was laid out neatly and ledgibly in columns 
making it easy to read. All the information was in- 
cluded; callsign, mode, frequency, date, time, country 
etc. No local stations were listed, no Eu stations 
either, just some 175 DX stations. A sample from this 
superb 14MHz s.s.b. log reads; AP2AD, CE3FM, 
CN8BB, CP1BG. CR5SP, CT1BT, EL2BA, EP2JA, 
ET3ZU, HC1M, HI1AGS, JY9DK, KH6CD, KP4FS, 
KZ5JW, LU2AGE, OA1BU, OA6BGI, PJ0PM, PY2FIQ, 
TI2FKB, VA2UN (special station in Montreal), four- 
teen VEs, VK1BT, VK2APK, VK3BCM, VK4CZ, 
VK4PV/P, VK5GX, VK60V, VK7RX, VK9CD, 
seventy Ws, XE1IIJ, YB5BFK, YN20M, YV1ACI/P5, 
YV4YC, YV5CKR, YV6EE, ZA2BE, ZB2A, ZC4LC, 
ZE1CW, ZL2BGV, ZL3GO, ZL4AW, 3A0FX, 3V8ZK, 
4X4JL, 4Z4DZ, 5Z4LW, 6Y5GA, 7X2BK, 9H1BG, 
9M2LP, 9Q5RN, 9V1QJ, 9Y4CP. 

Irwin Brown (Co. Antrim), has a JR-310 and a 
dipole at 30ft. Log of s.s.b. from 14MHz which was 
heard in the Emerald Isle includes; AP5HQ, EA6BM/ 
M, ET3ZU/A, H18LA, VE1CW/M, VQ9YL, YA2DD, 
YB3AAY, ZK1CD, ZM7AG, 5K5LR, 5Z5KL. 

Philip Cross (Preston) has an HRO-MX and a dipole 
cut for 14MHz. Log of s.s.b. reads; CN8GC, CR5SP, 
CR6IC, ET3ZU/A, FP9AR/M, HP9ARZ, HV3SJ, 
JA6YUV, JX1AK, JY1, LU2ECO, M1B, MP4TDM, 
OD5GC, PZ1DR, VQ9XX, VP9BN, ZE1CY, ZS3KC, 
3A2CP, 3V8ZK, 7X2BK, 7Z3AB, 9K2BG, 9J2ED, 
9X5AA, 9Y4VV. 

"I'm now working hard trying to learn c.w," says 
Alan Smith (Nelson). "Good lad," says David Gibson 
(Harpenden). Alan uses a Koyo KTR 1662 receiver 
and 25ft. of wire. Not an elaborate set up, but enough 
to hear some 14MHz s.s.b. from; EA6BU, HC1KH, 
HK3BN, KZ5IK, KP4BJD, PJ9AD, PZ1AY, VE3CNE, 
YB5FB, YV5AXT, 6Y5SR, 9Y4W. 

An ECC83 and ECL82 (leaky grid detector and a.f. 
amp), is the homebrew receiver of John Runchman 
(South Norwood). On 20 metres, with the aid of a 
dipole, John bagged; HK3UY. sixteen Ks, LU4ECO, 
PY2CAQ, VE1IJ, VP2LY, thirty Ws, YN1ABD, 
YV4UA, ZP5AN, ZL3AA, 4X4AE, 4Z4QAM, 6Y5GA, 
9H1M, which is pretty good going for two valves. 

P. Harris (Surbiton) RA-1, dipole, got these on 
28MHz; LU3DTV. LU6DRB, PY2HT. 

Goings on for contest-types at this time of the year 
includes: November 6-7, 144/432MHz c.w. contest; 
6-7, 40 metre phone contest; 6-8, CHC/FHC phone/ 
c.w. contest; 13-14, topband contest; 14, OK contest; 
27-28, CQ WW d.x. c.w. contest. December 5, 2 metre 
contest. 



Logs, in alphabetical order please, to arrive 
by the 15th of the month to: 

12 Cross Way, Harpenden, Herts. 



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Durable tinted plastic, attractive appearance. fc 



EMI PICK-UP ARM witb mono xtal and stylus £1-25. 
HI-FI PICK-UP CARTRIDGES. Diamond 8tereo/Mono. 
9TA £2 50; GP94 £2 50; GP93 £2 00; Mono GP91 £1 50; 
GC8 £1 25; ACQS L.P. only 60p. 




AM— FM/VHF GANG 

Super quality small sise 1J X 1) x 
l'ln.. plus spindle 1; X Jin. 865 + 
865 pF with 26+25 pF. BriUib 
made. Geared slow motion drive 
6:1. Plastic dust cover. 6BA tapped 
Iront fixing. 5Qn Post Free 



WEYRAD P50— TRANSISTOR COILS 



RA2W Ferrite Aerial . . 

Osc. P50/1AC 

I.F. P50/2CC 470 kc/s. 

3rd I.F. P50/3CC 

P61/1 orP51/2 

P50/3V 



65p 
30p 
33p 



Spare Cores 

Driver Trans. LFDT4 

Printed Circuit, PCA1 

J.B. Tuning Gang 

Weyrad Booklet 

OPTI 



3p 
50p 
50p 
65p 
lOp 
55p 



Mullard Ferrite Rod 8 x ;in. 20p. 6 x tin. 25p. 

VOLUME CONTROLS I 80oi.m Coax 4p. yd. 



Long spindles. Midget Size 
6 K. ohms to 2 Meg. LOG or 
UN. L/8 16p. D.P. 26p. 
STEREO L/S 55p. D.P. 76p. 
Edge 5K. S.P. Transistor 25p 



BRIT18H AERIALITE 
AER AXIAL-AiR SPACED 
40 yd- (1 40; 60 yd. £2. 
FRINGE LOW LOSS I f\ n , 
Ideal 625 and colour. Iw r«- 



WIRE- WOUND 3-WATT POTS. 
Small type with small knob. 
Values 10 O to 30 K . 
Carbon 30 K to 2 meg. 



25p 



WIRE-W0UND3-WATT 
STANDARD SIZE POTS. 
LONG SPINDLE A(\ n 
10 OHMS to 100 K~ U H 



VKROBOARD 15 MATRIX 
25 X 5in.19p.2J X Sjun.18p.3j x 8|in. 19p.31 x 6in.28p. 

EDGE CONNECTORS 16 way 25p; 24 way 88p. 

PINS 38 per packet 17p. FACE COTTERS 38p. 
8.R.B.P. Board 15 MATRIX 2Jin. wide 8p per lin.. 
3 Jin. wide 4p per 1 in.; Sin. side 5p per lin. (up to 17in.i. 
S.R.B.P. undrilled A in. Board 10 x 8in. 15p. 



r.g. 21n. sides. 7 x 4in. 
< 9in.90p;14 X llin. 



BLANK ALUMINIUM CHASSIS 18 ■ .« 

45p;9 x Tin. 60p: 11 x 71n.70p;18 : 

95p; 15 x 14in. 99p: 11 x Sin. SOp. 

ALUMINIUM PANELS 18 s.w.g. 6 x 4in. 9p; 8 x 6in. 15p; 

14 x Sin. 16p;10 X 7in.l9p;12 x 5in.20p;12 x 8ln.28p; 

16 x 6in. 28p; 14 x Bin. 34p: 12 x lgin 40p. 

li inch DIAMETER WAVE-CHANGE SWITCHES 25p. 

2 p. 2-way, or 2 p. 8-way or 3 p. 4-way 25p each. 1 p. 12-way. 

or 4 p. 2-way, or 4 p. 8-way 25p. 

1 inch DIAMETER Wavechange "MAKITS" 1 p. 12-way, 

2 p. 8-way, 3 p. 4-way. 4 p. 3-way, 8 p. 2-way, 1 water 60p, 
2 water SOp. Extra waters up to six 30p each. 
TOGGLE SWITCHES. «p. 14p ; dp. 18p : dp. dt. 88p. 



POST 
FREE 



R.C.S. STABALISED POWER PACK 

All parts and instructions with Zener Diode, Printed Circuit. 
Bridge Rectifiers and Double Wound Mains Translormer 
input 200/240v. AC. Output voltages available 6 or 9 or 
18 or 15 or 18 or 20v. DC at 100mA or less. 
PLEASE STATE VOLTAGE REQUIRED. £J 
Details S.A.E. 

GENERAL PURPOSE TRANSISTOR 
PRE -AMPLIFIER BRITISH MADE 

Ideal tor Mike, Tape, P.TJ., Guitar. Can be used with 
Battery 9-12v or H.T. line 2O0-800V D.C. operation. 
Size li" j: U" x J". Response 26 c.pj. to 25 Ke'i. 26db gain. 
For use with valve or transistor equipment. 
Full instructions supplied. . _ _ _ 90 D 



Bran 



Guaranteed. Details S.AJE. 



Post 
lOp 



NEW TUBULAR ELECTROLYTICS 





14p 


250/25V .. 


14p 


4/350V . . 


14p 


500125V .. 


SOp 






1000:85V.. 






lbp 


1000 '50V . 


47p 


32/450V 


20p 


8 '• 8/450V 


ltlp 




lOp 






50/60V 


lOp 


18 18 450\ 




100/25V 


lOp 


32 + 32/350V 25p 



CAN TYPES 
18 ■ 16/500V . SSp 
50 - 50:350V 35p 

80 - 100/350 V . 58p 
32^32/850V .. 18p 
32- 82/460V .. 38p 
350 ^60 /326 V 60p 
32^S8~38/360V 43p 
100 - 60 t 50/350V48P 
SUB-MIS. ELECTROLYTICS. 1. 8. 4. 6. 8. 16, 26, 30. 60. 100, 
200mF 15V lOp; 600. lOOOmF 12V 18p: 2000mF 25V 85p. 
CERAMIC lpF to 01 mF. 4p. 8ilver Mica 2 to 5000pF, 4p 
PAPER J50V-0 1 4p. 5 13p; lmF 15p: 2mF 150V 15p. 
5O0V-0 031 to 05 4p: 01 5p; 085 8p; 47 85p. 
SILVER MICA. Close tolerance 1»„ 2 2-500pP 8p; 500-2 200 
pF lOp: 2.700-5.600pF 20p; 6.800pF-0 01, mid 30p; each. 
TWIN GANG. "0-0" 208pF- 176pF. 85p; Slow motion drive 
365 • 385 with 25 - 26pF. 50p 500pF slow motion, standard 
45p; small 3-gang 500pF £1 60. SHORT WAVE. Single 25pF 55p 
CHROMK TELESCOPIC AERIAL, swivel base, 23in. 20p. 
TURING Solid dielectric. lOOpF. 500pF. 35p each. 
TRIMMERS. Compression 30. 60. 70pF, 5p: lOOpF. 150pF. 
8p: 250pP, lOp; 600pF. lOp: 760pF lOp; 1250pF lOp. 
SILICON REC. 40 LUCAS 2DS500 Bridge 70V 5 amp £1 
RECTIFIERS CONTACT COOLED I wave 80mA 88p;. 
85mA 48p. SILICON BYZ13 30p; BYI00 SOp; BY127 30p. 
EX-GOVERNMENT RECTIFIERS 250v. 200mA. 30p. 
NEON PANEL INDICATORS 250V AC DC Red or Amber 20p . 
RESISTORS, Itr.l w.. 20",, lp; 2 w. 6p lOfi to 10M. 
HIGH STABILITY. 1 w. 2 '„ 10 ohms to 1 meg.. lOp. 
Ditto 5"., Preferred valuea 10 ohms to 10 meg., 4p. 
WIRE-WOUND RESISTORS 5 watt, 10 watt, 15 watt, 
10 ohms to 100K. lOp each ; 2; watt. 1 ohm to 8 2 ohms lOp 

PHILIPS TRANSISTOR FM STEREO 
.,. •.V- 1 *»jJ a MUXTD7LEX DECODER. 

• Lai used in LEAK Troughiine 
- Tuner. Brand New. Pre- 
aligned witb 9 semi-conduc- 
tors. 24v. DC at 6mA. Com- 
plete witb circuit and con- 
nection details. £4 




lin. 



POST 
FREE 



MAINS TRANSFORMERS "SKS 

260-0-850 80 mA. 8 3 v. 4 amp £1 40 

250-0-260 80 mA. 8 3 v. 3 5 a. 8 3 v. 1 a. or 5 v. 2 a. £2 00 
350-0-350 80 mA. 6 3 v. 3-5 a. 8 3 v. 1 a. or 5 v. 2 a. £2 00 
300-0-300 v. 120 mA.. 8 8 v. 4 a. C.T. ; 6.8 v. 2 a. . £2 60 
MINIArURE 200 v. 20mA., 6 3 v. 1 a. 21 x 2J x 8in. 76p 
MIDGET 820 v. 45 mA.. 8 3 v. 2 a. 81 x S| x 8in. SOp 

P.E. AURORA TRANS. 12 - 12v„ 500mA £1 50 

MINI-MAINS 20v. 100mA. li x li x ljin SOp 

HEATER TRANS. 8 3v. 3 a 60p 

Ditto tapped sec. 1.4 v.. 2. 8. 4. 6. 6 8 v. 1J amp. 80p 

GENERAL PURPOSE LOW VOLTAGE. Tapped Outputs 
at 8 amp. 3. 4, 6, 6, 8. 9, 10. 18. 15. 18. 84 and 30 v. £2 00 

1 amp., 6, 8, 10, 12, 16, 18, 20, 24, 30. 36, 40. 48. 80. £2 00 

2 amp. 6. 8. 10, 12. 18. 18. 20. 24. 30. 36. 40. 48. 60. £3 '00 
AUTO TRANSFORMERS 115v. lo 230v. or 230v. to 116v. 
Input/Output. 150w. £200; 600w. £5; lOOOw. £18. 
CHARGER TRANSFORMERS. Input 800/850v. 

tor 6 oi 12v.. li amp.. £1-80: 8 amp £1-50; 4 amp. £2-00. 
FULL WAVE BRIDGE CHARGER RECTIFIERS: 
6 or 12 v. outputs, li amp. 40p: 2 amp. SSp: 4 amp. SSp. 
All translormers Postage 26p extra. 




E.M I. 13V x 8in. 
LOUDSPEAKERS 

£4 



With twin tweeters 
and crossover, 10 watt. 
State 3 or 8 or 15 ohm. 

(As illustrated) 



Witb flared tweeter cone and ceramic 
magnet. 10 watts. r-\ *\r 

Baas res. 46-80 cps. tZ'ZD 



Flux 10,000 gauss. 
State 3 or 8 or 15 ohm. 



Post 15p 



Recommended Teak Cabinet 
Size 16 x 10 x Sin. Post 25p 



£5 



"THE INSTANT" 
BULK TAPE 
ERASER AND 
RECORDING 
HEAD 
DEMAGNETISER 

Minimum Pose and Packing ISp RETURN OF POST DESPATCH. HI-FI STOCKISTS. 

RADIO COMPONENT SPECIALISTS 




200 MM 
v. A.C. 
Leaflet 
8.A.E. 

£2-35 

Post 15p 



I0W MINI-MODULE £3«25 
LOUDSPEAKER KIT re a* 

Tripln speaker system combining on ready cut baffle, 
i in. chipboard 15 in. x 81 in. Separate Bass, Middle 
and Treble loudspeakers and crossover condenser. The 
heavy duty 6 in. Baas Wooler unit baa a low resonance 
cone. The mid-Range unit is specially designed to add 
drive to the middle register and the tweeter recreates the 
top *nd ot the musical spectrum. Total response 
80-15,000 cps. Full Instructions tor 3 or 15 ohm. 
TEAR VENEERED BOOKSHELF ENCLOSURE. 
16| :< 10) x Bin. Modern Design, dark 
grey Tygan covered baffle or with fluted £5 „ 



vood Iront 16 x 10 x Sin. 



ALL MODELS "BAKER SPEAKERS" IN STOCK 



BAKER llin. MAJOR £9 



» ■ ■ 




30-14.500 c.p.s., 18in. 
double cone, wooler and 
tweeter cone together 
witb a BAKER ceramic 
magnet assembly having 
a flux density ot 14,000 
gauss and a total flux ot 
145.000 Maxwells. Bass 
resonance 40 o.p.i. Rated 
80 watts. Voice coils 
3 or 8 or 16 ohms. Post Free 



Module kit. 30-17.000 c.p.s. 
with tweeter, crossover. 
baffle and ril rn 

instructions. fc * ■ JW 



BAKER "BIG— SOUND" SPEAKERS 

'Group 25' 'Group 35' 'Group 50' 

12 inch fi 12 Inch /Q 15 inch /It) 

25 watt *•' 35 watt *•' 60 watt s,,# 

3 or 8 or 15 ohm 3 or 8 or 15 obm 8 or 15 ohm 



TEAK HI-FI SPEAKER CABINETS. Fluted wood tront 
For 121n. dia. speaker 20 x 13 x 9in. £8. Post 25p 

For 13 x 8in. speaker 16 x 10 x 9in. . . £5. Post 25p 

For 10 x Bin. speaker 18 x 8 x Bin £4. Post 26p 

LOUDSPEAKER CABINET WADDING 18in. wide. 15p It. 



GOODMANS HI-FI WOOFER 

8 ohm, 10 watt. Large ceramic magnet. 
Special Cambric cone surround. Frequency 
response 30-12,000 cps. Ideal P.A. Columns. 
Hi-Fi Enclosures Systems, etc. £A 



• 




ELAC CONE TWEETER 

The moving coil diaphragm gives a good 
radiation pattern to the higher Irequencies 
and a smooth extension ot total response 
tram 1.000 cps to 18,000 cps. 8ixe 3* x 
3i x 2in. deep. Rating 10 watts. 3 ohm 
or IS obm models. 1 I , OQ 



Post 



10p 



Horn Tweeters 2-16kc/s, 10W 8 ohm or 15 ohm £1-60. 

De Luxe Horn Tweeters 2-18 Kcis. 1SW. 8 obm £3. 

TWO-WAY 3000cps CROSSOVERS 3 or 8 or 15 ohm 95p. 

SPECIAL OFFER! 80 ohm, 2jln. dia.; 35 obm. 2in.: Sin 

25 ohm, 2)in. dia.;3in. dia.;6x4ln.;8xSln. f\ EACH 

15 ohm. 31in. dia.; 7x4in.: 8x5in. *-* TYPE 

8 ohm, 6x4in. 3 ohm. 8tin. Sin. 5ln. 6x3in. 7x4in. 

LOUDSPEAKERS P.M. 3 OHMS. 6|in. £1.10; 8 x Sin. £1 86; 

8 X 21in. SOp; 8in. £1.76: 10 x Sin. £1.90. 

5in. WOOFER 8 watts max. 80-10.000 cps. 8 or 15 ohm. £1 80. 

ELAC 8 in. De Luxe Ceramic 3 ohm or 16 ohm £2 SO. 

RICHARD ALLAN TWTN CONE LOUDSPEAKERS. 

8in. dia. 4 watt; lOin. dia. 6 watt; 12in. dia. 6 watt 

8 or 8 or 16 ohm models £1.95 each. Post 15p. 

OUTPUT TRANS. EL34 etc. 25p: MIKE TRANS. 50:1 25p. 

SPEAKER COVERING MATERIALS. Samples Large S.A.E. 

GOODMAN'S OUTPUT TRANSFORMER 5 watt push-pull 

lor valvea EL94 etc.. 3. 8 and 15 ohms 85p. Post 20p. 

BAKER 100 WATT ALL 

PURPOSE POWER 

AMPLIFIER 

4 inputs speech and music. 

Mixingtacilities.Response 

10-30.000 cps. Matches 

all loudspeakers. A.C. 

200/860v. Treble and 

Bass controls. Guaranteed. flQ 

Details S.A.E. *- J ' 




ALL EAGLE PRODUCTS 

SUPPLIED AT LOWEST PRICES 
ILLUSTBATED EAGLE CATALOGUE 20p. Post Free . 

BARGAIN AM TUNER. 
Transistor Superhet. Ferri 



£4 



BARGAIN 4 CHANNEL TRANSISTOR MIXER 
Add musical highlights and sound effects ti recordings. 
Will mix Microphone, records, tape and tuner £"} 

with sepsrate controla into single output. 9 volt. ■"* 



BARGAIN FM TUNER 8S-108 Mc s Six Transistor. 9 volt 
Printed Circuit. Calibrated slide dial tuning. ( I ft 

Walnut Cabinet. Siaa 7 x 6 x 4lnch fc ■ " 

BARGAIN FM TUNER as above lea* cabinet £7-50 



BARGAIN 3 WATT AMPLIFIER. 4 Transistor / I.Kft 
Push-Pull Ready built, witb volume control. 9v. *■•* ""* 



COAXIAL PLUG 6p. PANEL SOCKETS 6p. LINE 18p. 
OUTLET BOXES. SURFACE OR FLUSH 26p. 
BALANCED TWIN FEEDERS 5p yd. 80 ohms or 300 ohms. 
JACK 80CKET Std. open-cirouit 14p. closed circuit 28p; 
Chrome Lead Socket 45p. Phono Plugs 5p. Phono Socket 5p. 
JACK PLUGS Std. Chrome I5p; 3 5mm Chrome I4p. DIN 
SOCKETS Chassis 3-pin 10p; 5-pln lOp. DIN SOCKETS Lead 
3-pin 18p: 5-pin 26p. DIN PLUGS 3-pin 18p: 6-pin SSp. 
VALVE HOLDERS, 5p; CERAMIC 8p: CANS 5p. 

E.M.I. TAPE MOTORSpost 15p. 
120v. or 240v. AC. 1.800 r.p.m. 4 pole 
135mA. Spindle 0-187x0 75in. £ I ,1C 
81xe3ix2}x2!in. (iUustrated). fcl *•* 
BALFOUR GRAM MOTORS 
120v. or 840v. A.C. 1.800 r.p.m. 4 pole 
60mA. Spindle J x 3/20. 81x6 g[J 



«l 



2! x 21. X l|in. 
CUSTOMERS FREE CAR PARK. 
337 WHITEHORSE 



Post 15p 
CALLERS WELCOME 
ROAD, CROYDON 



Optn 9-6 p.m. (Wednesdays 9-1 p.m., Saturdays 9-5 p.m.) 
List 5p. Written guarantee with every purchase. (Export: Remit cash and extra postage.) Buses 50. 68, 159 pass door. S.R. Stn. Se/hurst. Tel. 01-684-1665 

727 






Fully guaranteed 

Individually packed 

VALVES 

B12H £l-7SpiECH200 62p'OA2 



CY31 

DAF96 

DF96 

DK96 

DL92 

DL94 

DL96 

DM70 

DY86 

DY87 

DY802 

E88CC/01 

£l-80p 
E1S0CC 42p 

F.isiec 90p 

E182CC 

£105 

EABC80 32p 



3Sp I ECL80 
S8p , ECL82 



45p 



37p 

ga 

32p 
40c 
41 1 
30p 
45p 
oop 
4Sp 



EAF42 

EB91 

EBC33 

EBC41 

ECC81 

EBF80 

EBF83 

EBF89 

ECC81 

ECC82 

ECC83 

ECC84 

ECC85 

ECC86 

ECCSS 

ECC1S9 

ECF80 

F.CFR2 

ECF83 

ECF801 

ECF802 

ECH35 

ECH42 

ECH81 

ECH83 

ECH84 



ECL83 

ECL88 

EF36 

EF37A 

EF39 

EF40 

EF41 

EF80 

EF83 

EF85 

EF86 

EF89 

EF91 

EF92 

EF95 

EF183 



OBJ 



PABC80 37p 



PC97 

IV-t'on 
46p I PCCS4 

45p I'd ■■".! 



50P.EF184 
16piEFL200 
50p I EL34 
S2p F.T.4 1 



EL42 
EL84 
F.L85 
EL86 
EL90 
KT.V.-i 
ELS 00 
EM31 
EM80 
km-; 
EM87 
EY51 
EY86 
EY81 
EY88 
62p EZ41 
82p EZ80 
EZ81 
(JZ34 



PCC189 
PCB8M 

PCF80 
PCF82 
PCFH4 

I'l'l'-li 

PCF200 

ITI-.ll 

PCF801 
FCK602 
PCF80S 
PCF806 
PCFSOS 
POH200 
PCL81 
PCL82 
58p I PCL83 
28p.PCL84 
40p • PCL83 
40p | PCL80 
3bp|PFL200 



TRANSISTORS, ZENER DIODES etc. 



SPECIAL 
OFFER 

09J tube 

£1-75 



OAS 

OA10 

OA70 

OA71 

OA73 

OA74 

OA79 

OA81 

OA91 

OA200 

OA202 

OA210 

OA211 

OAZ200 

OAZ201 

OAZ202 1 

OAZ206 42p 

OAZ207 

OAZ208 

OAZ213 32p 

OAZ223 to 

OAZ225 50p 

OC1S SOp 

OC22 SOp 



OC25 
OC26 
OC28 
OC29 
OC35 
OC38 
OC44 



lOp : OC45 
lOp OC70 



OC200 
OC201 
OC206 
IN21 
IN".' IB 
IN25 
IK 43 
INTO 



40p 1 2N3055 
60p 2N8730 



m 

25 

HOp 
10p 



2N3731£275p 
2N5109£2-05p 
40302 60p 
82303 SOp 
3F100 67p 



OC71 
0C72 

OC73 
OC75 

OC76 25p 

OC81 25p 

OC81D 20p 

OC81DM 20p 

OC82 25p 

OC82DM SOp 

OC83 esp 

OC83B lgp 

47p OC84 26p 

OC122 60p 

OC139 26p 

OC140 87p 

OC170 25p 

OC171 80p 

OC172 S7p 



lX702-72586p 



7p 3PR5 



15p 1NS23AH-30 
25 p IZMT5 8Sp 
30p IZMT10 "' 



IZT5 

IZT10 

2G385 

2O403 

IN4785 

2N277 

2X918 

2N1304 

2N1300 

2N1307 

2N2147 

2N2904A 38p 

2N30B3 

2X3054 



33p 
67p 

Bta 

51p 
15p 
.iOp 
52p 
37p 
25 p 
25p 
25p 

7Sp 



3X128 



3X139 £1 75p 
3X140 9Sp 
3X154 90p 
3X159 £l-45p 
APRS 46p 
12FR60 73p 
10D1 16p 

40594 £1 87p 

40595 £l-87p 
40636 £l-45p 

40668 £l-35p 

40669 £l-4Sp 
AC126 25p 
AC127 25p 
AC128 25p 
AC176 25p 

26p ACY17 SOp 
S0plACY28 17p 



AD149 
AD161 
AD162 
AF118 
AE127 
AF139 
AF178 
AF186 



BYZ13 2Sp 

BYZ16 63p 

CB81/10 2Sp 

C RS 1/20 38p 

CRS1/30 40p 

C i'.S 1/35 43p 

C 381/40 48p 

C 583/05 30 p 



AFY19£l-13pC 383/20 38p 
A8Y26 25p (333/30 43p 
25p!c 5325/02 



ASY23 

ASY67 

BAW19 

BC107 

BC108 

BC113 

BC118 

BCY72 

BF115 

BF173 

BFY51 

BFY52 

B805 

BS 

BS2 

B3Y29 



4Sp 
2Sp 

m 

12p 
25p 
38p 
lop 
25p 
30p 
20p 
23p 
3Sp 
45p 
47p 
25p 
BU10O£l-8Op 



75p 

C3S3/40 SOp 
GET103 23p 
GET115 45p 
GET116 SOp 
GBX66 £100 
XKT222 20p 
NKT304 SOp 
81)918 26p 



81)928 

SD938 

31)94 

81)988 

V405A 



31 p 
32p 

21p 

46p 
40p 



KT66 £l-60p 
KT88 £216p 
N78 £126p 



42p 
42,) 
57p 
53p 
50p 
40 P 
42|> 
35 p 
73p 
75p 
BOp 
35p 
27 p 
27p 
35p 
37p 
52p 
S2p 
QQVO3-10 

£l-25p 



PL36 

PL81 

PL82 

PL83 

PL84 

PL500 

PL604 

PY33 

PY80 

PY81 

PY82 

PY83 

PY88 

PY800 



42p J QQVO6-40A , CRC41 
£5 25p UBF80 

R17 46p UBF89 

R19 87p UCC85 

8TV280/40 luCF80 
£3 OOp ! UCH42 

8TV280/80 | UCH81 
£9 OOp UCL82 

TT21 £2-75p 

U2B 76p 

U26 75p 

U27 50p 

T191 70p 

USUI £100 

UABCRO 38p 

UAF42 65p 



UCL83 

UF41 

OF80 

UF89 

UL41 

UL84 

UU5 

UY41 



47p UY85 30p 

35p I VR 105/30 86 

35p.VR150/30 3Sp 

40p i Z759 £1 6Sp 

55pjZ801U£15-0p 

70plZS03A £1 JJSp 

35p ! Z900T 75p 

35piIL4 

SOp! IR5 

SOp I 134 

38p 135 

35p!lT4 

BOp 1 1X2 A 

30p 1X2B 

56p 3A4 

4Sp 1 300 



3Q4 

334 SSp 

3V4 4Sp 

5B'j54M£2-20 

5B/255M 

£178 
5R4GY SOp 
BU4G 
6V4G 
6Y4G 
6Y3GT 
BZ4 
6Z4GT 
6AB7 
6AC7 
6AH6 



30p 



37p 6AK5 
6AK8 
6AL5 
6AL5W 
6AM6 
6AN8 
6AQ5 
6AQ5W 
6A86 
6AS7G 
6AT6 
6AU6 

6AX4GT 40p 
6AX5GT SSp 
6B7 40p 

6BK7 40p 



611A6 

6HE6 

611G6G 

6JIJ6 

611Q7A 

61IR7 

6BW0 

6IIW7 

6tV4 

6C« 



SSp 
15p 
40p 
30p 
50p 
35p 
50p 
3.'p 
SOp 
30pl6<:U6 



25p 



ecifi 

61)6 

6EA8 

6F23 

6J'33 



MANY OTHERS IN STOCK incluit Cathode Ray Ti4bei and Special Va'.vei. 
P. & P. Up to £1 12p, £l-£2 i7p, £2-£3 22p. Over £3 post free. C.O.D. 20p extra. 



2Sp 
SOp 
55p 
45p 
SSp 
SOp 
80p 
70p 
30p 
25p 
SSp 
4Bp 
20p 
SSp 
76p 
£1-S0 
U.K. 



29/41ft. AERIALS each consisting ol ten 3ft. iin. dla. 
tubular screw-in sections. 11ft. (6-sectlon) whip aerial 
with adaptor to fit the 7ln. rod, Insulated base, stay 
plate and stay assemblies, pegs, reamer, hammer, etc. 
Absolutely brand new and complete ready to erect. 
In canvas bag £4. P. & P. 50p. 

MCTCPC Full List of our very large 

■"*• ■ ^r%«i* stock of meters on request. 



INTERGRATED CIRCUITS- 
MANY OTHERS IN STOCK 

RCA. CA 3005 wide band R.F. Ampl. 300mW diss £1-20 
CA 3012 wide band ampl. 150m Wdlss .. .. £0-90 

CA 3020 Audio power ampl. £1-37 

CA 3036 Audio pre-ampl £0-90 

General Electric PA 230 £1-40; PA 234 £1: PA 237 £2-10 
Mullard TAA 300 £1-75; TAA 320 73p 



« 



ALL valves 
guaranteed 



6116 


20p 


I2K.> 


SSp 


957 


SOp 


6J4WA 


75p 


12K7GT 


4(lp 


991 


40p 


6J5 




12K8GT 


45p 


1622 


£l-00p 


6J5GT 


25p 


12Q7GT 


SOp 


2051 


SSp 


SJ6 


20p 


128G7 


Hf>p 


5933 


£1 12p 


6J7G 


8bp 


1487 


75p 


6057 


50p 


6J7M 


40p 


19AQ5 


40n 


6060 


SOp 


SK6GT 


Mlp 


19G3 £4-25p 


6064 


45p 


6K7 


»2p 


19G6 £1-S0p 


6065 


SSp 


6K7G 


20p 


19H4 £5-00p 


6080 


£1 37p 


6K8GT 


4op 


20P4 £l-00p 


6146 


£1 SOp 


8K25 


;op 


25L6GT 


40p 


8020 


£2 26p 


68A7 


4llp 


30C15 




9001 


20p 


63A7GT 


32p 


30C17 


HOp 


9002 


2Sp 


88C7GT 


2Sp 


30C18 


75p 


9003 


SOp 


68G7 


Sop 


30F5 


K4p 


9004 


ISp 


68J7 


87p 


30FL1 


70p 


9008 


16p 


IIS.ITIIT 


82p 


30FL12 


92p 


C.R. Tutei 


68K7 


35p 


30FL13 


blip 


VCR97 


68L7UT 


KKp 


30FL14 


7Sp 




£4 50p 


68N7GT 


»5p 


30L15 


85p 


VCR517B 


6SQ7 


3Up 


30L17 


HOp 




£3 50p 


68Q7GT 


Sop 


30P12 


Htlp 


VCR517C 


6V6G 


17p 


30P19 


80p 




£750p 


6V6GT 


SSp 


30PL1 


;op 


5FP7 


£l-32p 


6X4 


27p 


30PL13 




88D 


£900p 


0X5G 


2Sp 


30PL14 


85p 88 J 


£9 OOp 


6X5GT 


82p 


35L6GT 


SOp 


88L 


£9 OOp 


6Y6G 


SOp 


35 W4 


KOp 


Photo Tubci 


8-30L2 


70p 


35Z4GT 




CMG25 


BZ4 


82p 


42 


45p 




£2 75p 


7B7 


4hp 


50C5 


40n 


931A 


£3 50p 


7CS 


HSp 


50CD6G30 


6097C 


7C6 


4Up 


£160p 




£1750p 


7117 


32p 


50EU5 


KOp 


Special VIti 


7Y4 


HOp 


75 


40p 


CV10S1 


9D6 


87p 


76 


40p 






11E2 £2 SOp 


78 


4(lp 


CV2339 


12AT6 


SOp 


80 








12AT7 


SOp 


80S £8-25p 


JP9/' 


D 






805 £800p 






12AV6 


SOp 


807 


blip 


K301 


£500p 






813 £3-75p 




12BE6 




832A £300p 
860A 75n 


K308 £16 OOp 


12BH7 


V,7p 


954 








12C8 


S2|) 


955 


40p 


5C22 


£18 OOp 


12E1 fl-25p 


956 


20p 


725A £18 OOp 



Colomor (Electronics) Ltd. 

170 GOLDHAWK ROAD, LONDON W12. 
Tel: 01-743 0899 
Open 9-12.30. 1.30-5.30 p.m. Thursday 9-1 p.m 




MW'LW TRANSISTOR RADIO 



Complete set of parts for this MW/LW 
Transistor Radio. Originally sold by 
world-famous company as a set for more 
than £17. Coverage 192-555m + 1070- 
1870m. 9 volt 6 transistor superhet 
using 3 AF117 in RF and IF stagra 
powered by a two stage AF amplifier using 
8XAC128. Output approx. BOOMW. 
Also works iofl car-aerial. Full in- 
Ktrucllon book 12ip free with parts. 
Red only, ply case, reilne covered. 
Requires PP7 batt«ry. price 22!>p extra. 
3iln high-quality speaker. Price £8 plus 
40p P. A P. 



STEREO AMPLIFIER Type SHV— 2 x 3 watts 

Fully built. Separate vol., base and treble controls 
each channel; 12 x 41 X Sin high. EZ80 and 
2 x ECL86 valve?. OS. trans, for 3-ohm speakers. 
Double wound mains trans. Suitable for crystal, 
magn. cartridge, tuner, etc. with mono-stereo 
switch. 200-250V a.c. mains. £7-25. 60p P. * P. 





A.M./FJU. (V.H.F.) tuning gang / 3 >: 2 x 1 |ln 
plus spindle Iin (Jin dia.) 400 + 180 + 20 + 
20pf ; geared slow motion drive 8:1: 
no back lash ; cast frame ; Brand new ; 
Onrman ; 3 :■■ 4b.a. fixings. 86p post pd. 
less 10% for 6. 



MAINS TRANSFORMERS (240-250V input) 

Postage in brackets 

6-3V at 2 (A, 40p (ion i 

250V at 50mA and 6-3V at 1JA, SOp (20p). 

22V at 1A, 6-3V at 2A and 250V at BOmA, 75p (25p). 

90V at 20uiA and 1-4V at 250mA, SOp (15p). 

Ueiluct 10 per cent from total bill for more than one transformer. 




Miniature A.M. transistor tuning .gang. 250 + 
2B0pf : 2 X lib.a. fixings, size lj x lj x lln ; 
gearing 3 : 1 to A in dia. moulded bush. Plastic 
dust cover ; Plessey. 

25p post pd., less 10% for 6. 



GLADSTONE RADIO 

66 ELMS ROAD. ALDERSHOT. Hants 

(2 min». from Station and Bu«s). FULL GUARANTEE. Aldershot 22240 
CLOSED WEDNESDAY. 8.A.E. for enquiries please. 



Selections from FELSTEAD ELECTRONICS' List 

( Sent free for stamped addre tsed envelope to address below) 

Transistors etc. AC12S 12|p AF116 20p. AF116 ISp. AF117 20p. OA5 7,p. OA10 7lp. 
OA81 7ip. OA85 7Jp. OC23 82lp. OC25 SOp. OC26 87Jp. OC28 42}p. OC35 Ota. OC44 
14p. OC45 12,p. OC71 12,p OC72 12Jp. OC75 181p. OCS1 12jp. OC81D 12Jp. OC82D 
12ip. OC170 20p. OC171 12,p. Many more In list. 8J).R. BY100 800plv 14p. vChargcs 
Oip up to 11, paid for 12 ard over). Sub-Min Transformeis: OUTPUT 3 Q for OC72 etc.) 
14p. DRIVER ISp (up to 6, 6, p). SOLDERIIIO IROK. Slim, modem, British highspeed 8}', 
all parts replaceable, highest quality, full guarantee: £107 f (IOp), DIAMOND STYLE Ru- 
placements for BSR TC8/L?, TC8/S. TC81.P/HTF.REO: COLLARO 'O' : RONETTE 
BF 40LP: Garrard GC2/LP and GC8/LP: ACOS GP65/67, all at 40p (6p). AC08 GP73, 
GP91, GP91SC.GP104- BSB 3T4 (ST3, ST5),ST8 rST9); RONOTONE 8TA. 9TA.9TAHC; 
PHILIPS AG3306, 3060 (30C3, 3066, 3301, 3302. 3304): Garrard GKS25. GCM21, GCS23 
ami many more 'Garrard' eta. types. All at 75p. (fip). All are of the very highest quality 
DOUBLE DIAMOND: ST4 (ST3, 8T5); 8T10 (8T9, 8T8): 9TA, 9TAHC, 3306, GP91 (For 
(iP92. GP93, GP94 cartridges! : GP91-SC for all OP91-SC Cartridges. All at £1-60 each (6p). 
SAPPHIRE STTLH. All those types shown above under Diamond Stylii at 40p' also GP37 
at 17,p each (5p> and GP91 and GP91SC at 40p <5p). No others. PICK-UP CARTRIDGES. 
All Standard fittings and st.lii. Slono GP67/2 SOp. STEREO-COMPATIBLE (MOSO). 
GP91/8C £110 STEREO GP93 £180 STEREO CERAMIC GP94 £1-85 SOSOTOKE 



Cassettes in list, MICROPHONES. CRYSTAL: Mlo 91, hand/desk 81p. MIC45. Curved 
metal hand-grip £1-00. CM2 . Grey hand desk 62|p. Stick '60' £1 02!. CM70 "Planet" 
machined metal tapered stick type with neck cord, adaptor to fit floor stands £1 471 
(all 9p). LAPEL (or hand) -rith clip 32Jp (6p). All arc fltUd with leads. DYNAMIC: 
Type 209 Cardioid baU, 50K/100 C3. omnl-dir.. built-in vol. control, on/off switch, special 
lead, handle (as good as mor.ey can buy) £8-30. UD130 Uni-Dir. Ball, mesh, 60K/600n. 
A.ian.. cable, jack plug £4 80. C20p). DM160, omnl-dir., Ball, 50K Cable adaptor £3 87, 
(all at 27jp). MICROPHONE INSERTS. Dia., 1-78' OR 0-9" either size 27jp (6p). EAR- 
PIECES with lead and mln. j»ck plug (2-5 or 3-5 mm., state which). Magnetic 9p Crystal 
(3-5 only) 24p (Up to 3 for 6p on any). HEADPHONES De-luie STEREO 8-16 Ohms 
£2-47J. Same, fitted vol. control each earpiece £4-20. Both have lead and stereo jack 
plug (17Jp). High Res. 2000 ohm. Adjustable 92Jp <7Jp). SPEAKERS 12- ROUND fitted 
tweeter, 3 of 15 n (state wh oh) £1-87J (27Jp) or for Stereo £4-28 pair, carr. paid. 2J*, 
3 OR 8 J2 (state which) 87Jp !6p). EMI 13" X 8". 3. 8 or IB Q (state which) £2121 (2Bp) ; 
with two tweeters and crosiuiver network 15 fi £3-75 (25p). VIBRATORS. 12V 4-pin 
non-synch. 121HD4, 2j' ex. pin s. 27 1 p. 12V 7-pln Synch. (12SR7) 62Jp. (Both types 
SJp per vibrator). CONNECTING WIRE. Packs of 5 colls aestd. cols. ea. coll 6yds. Solid 
core 14p (6p). Flexible ISp ilp). Super thin for transistor wiring ISp (6p). PICK-UP 
WIRE . Super thin, twin flex, screened and sheathed 6p yd. (6p up to 6yds. — over free). 
RETRACTABLE Flex. Leads (Curlles) Phonoprag each end 12ft. 89p. 6ft phono plug/ 
phono socket other end 25p. 12ft 42)p (6p per lead all types). BATTERY ELIMINATOR. 
Input 240V A.C. Output 3V 6V, 7JV and 9V D.C. at 400 m/A. Switches, leads, pilot 
light, adaptor to suit most transistorised sets and cassette recorders £3-15 (25p). SEND 
8.A.E. for full free list of mains eliminators, amplifiers, extension aerials (car and port- 
able), electrolytics, vol. controls, more microphones, transistors, thyriators and SDRs 
and other devices, switches o* many types, rotary, toggle min. and sub-mio. slide types, 
multitest meters, panel mete-s, all types of British and continental plugs and sockets, 
croc, clips, terminals, valve holders aloo Goldrtng G800 series cartridges eta. etc 'Special 
Offer" lines at very low prices. 

FELSTEAD ELECTRONICS (PW 51) 

LONGLEY LANE, GATLEY, CHEADLE, CHES. SK8 4EE 

Cash with order only. No COD or Caller Service. Charges (Min. 6p) in brackets after all 
items. Regret Orders under 25 ? excluding postage, unacceptable. 8AE please for enquiries 
or cannot be replied to. Chaiges apply G.B. and Eire only. Overseas orders welcomed 
(lists free overseas). 



728 



LETTERS 



The Editor does not necessarily endorse the views expressed by correspondents 



Electronic Vandals 

As an amateur archaeologist 
and also as a reader of your 
journal for nearly 20 years, I 
would like to applaud your 
editorial on "Electronic Vandals." 

We as archaeologists do not 
want to deprive folk of their 
pleasures, but in return we ask 
that they in turn do not deprive 
us of vital information. 

A coin or a metal brooch, so 
badly corroded as to be almost 
worthless as a coin may, in expert 
hands of conservationists at 
museums, tell us the date when 
Roman forces were active in a 
fort or when a Roman villa was 
last occupied. 

We may have worked for many 
years patiently working out the 
size, shape and function of a 
structure; but if our dating evi- 
dence has been removed all our 
work becomes fruitless. 

If some of your readers honestly 
wish to help in furthering human 
knowledge then I suggest they 
contact their local archaeological 
society through their museum. It 
may be that they would be grate- 
ful for their help. Please remem- 
ber that archaeology is a study 
of people and not a treasure hunt. 
— J. L. Cole, (Sutton Coldfield). 



Beginners' Licence 

Although there are many Ama- 
teurs, who have worked hard to 
acquire their radio licence, and 
are now fully fledged Amateurs, 
I fail to see why the G.P.O. have, 
as yet, not introduced a "begin- 
ners' " licence. Such a licence could 
not fail to please all, as it would 
undoubtedly benefit the amateur 
radio movement, would encourage 
enthusiastic people to join, and 
would not clash with the activities 
of the fully licensed Amateur. 

I feel that a "beginners" licence 
is necessary as there are lots of 
potential Amateurs, who either 
don't have the facilities or don't 
have the time. I am sixteen years 
old, a keen SWL, but am in the 
middle of my 'O' Levels, and I 
will be continuing my studies for 
the next two years, and have 
therefore no time with which to 
study for the R.A.E. I am sure 
that there are many others, who 



are in a similar position. A limited 
licence would sow a good ground- 
ing and this would enable one 
to acquire a licence at a later 
date. 

Such a licence could be based 
on the following terms, and con- 
ditions: 

(1) A written exam comprising: 

(a) Section one of the 
present exam; 

(b) Frequency control and 
measurement; 

( c ) Interference, the causes 
and suppression of it; 

(d) Full operating proce- 
dure (this should relieve 
many qualified "Hams"); 

(2) The G.P.O. morse test; 

(3) (a) Only able to use a 

small allotted section of 
the band; 

(b) Limited to two watts 
power output; 

(c) C.W. transmission only; 

(d) The allocation of a 
"beginners" prefix. 

These conditions would, by 
their very nature, urge the will- 
ing and genuine Amateur on to 
the full licence while the lazy, 
and unenthusiastic would fall by 
the wayside. — M. S. Lerner, (Hen- 
don, London). 



Take— 20 Dollars 

Recently I started to construct 
one of the "Take 20" projects and 
I was horrified at some of the 
local prices for parts. These 
prices may be of interest to you: 
5,uF 12V capacitor, 20 cents; 
l-5Mfi * 4 W resistor 10 cents; 
BC109 transistor, $l-85c; BC169C 
transistor $2 -25c. Ten New 
Zealand cents is equal to 5p. 

It is actually cheaper to have 
these parts air-freighted from 
Britain than to buy them from 
the local shop. — K. B. Moore 
(Tokoroa, New Zealand). 



A Protest 

Radio components are clearly 
inferior to the previous designed 
ones, when silk covered windings 
of transformers were impregnated 
with quality varnish. Modern 
methods use enamelled wire im- 
pregnated with wax resulting in 
what I think is an inferior com- 



ponent which cannot be relied 
upon. 

Oil insulated windings are in- 
ferior, especially when mains vol- 
tages are used in primary wind- 
ings of transformers. Enamelled 
wires are clearly inferior and 
unreliable. More so when wax im- 
pregnated. 

We are progressing in the wrong 
direction. When will the proven 
system return, so that quality 
returns? I refer to transformers 
only but other components are 
quite often just as bad. — R. Wib- 
berley, Nottingham. 

Such a D.I.N. 

I would like to say a few words, 
aimed at manufacturers and sup- 
pliers: Now that "D.I.N." con- 
nectors are becoming more 
popular and standard on most 
equipment nowadays, how about 
making 5-core cables readily 
available, and 4-core individually 
screened cables at least available, 
if not readily available? — R. 
Williams (St. Albans, Herts) 



Treasure Traced 

We have been using a metal 
locator manufactured by a well- 
known company for some time 
now and recently our Town Hall 
called upon us to help search for 
a very expensive diamond and 
sapphire ring which had been lost 
on the beach. 

We tried a manufactured 
metal locator which proved use- 
less near salt. When we used the 
P.W. Treasure Tracer, we found 
the ring after one hour. The P.W. 
locator was not affected by water 
at all and the ring was in salt 
water when located. 

This was the first time we had 
put the P.W. Treasure Tracer to 
work and since the ring we located 
was worth about £200 it proves 
how good it is. Needless to say, 
the lady to whom the ring be- 
longed is very grateful and I hope 
other readers will have as much 
success. 

The cost to build the Treasure 
Tracer is so low for such perform- 
ance that the P.W. circuitry gives. 

I must add that we also found 
about a dozen coins before finding 
the ring. — R. Miller (Brightling- 
sea, Essex). 

729 




AN INTRODUCTION 10 FAULT-FINDING 



PART 7 



G. J. KING 



GORDON KING CONTINUES THE SERIES DISCUSSING TUNER-AMPLIFIERS AND THEIR PROBLEMS, 
PICKUPS AND THEIR ASSOCIATED CORRECTION NETWORKS AND ENDS WITH A BRIEF RESUME OF 
HI-FI AMPLIFIER SPECIFICATIONS. 



I want to begin this month with the hi-fi type of 
radio receiver, called the tuner-amplifier. This is 
an integration of a stereo (two channel) amplifier 
and a radio receiver always tuning the f.m. band 
(Band II) and sometimes a.m. bands as well, and 
invariably embodying a stereo decoder. This type of 
equipment is ousting the ordinary radiogram in 
certain areas of application, for, coupled to a pair of 
good speaker systems and a record playing unit the 
tuner-amplifier constitutes the 'heart' of a music 
system of significantly greater quality potential than 
the average radiogram. 

Real hi-fi radio reproduction is not possible from 
the a.m. bands owing to the necessary restrir'ion of 
the i.f. passband to avoid interference between 
adjacent stations. Sadly, even such passband restric- 
tion is unable to keep unwanted stations from the 
wanted in the medium waveband after dark, and as 
a consequence we get an annoying background of 
whistles and monkey chatter. Moreover, the passband 
restriction deletes the higher-order sidebands of the 
modulated signal and hence impairs the treble 
output. 

With f.m. things are not like this because in 
Band II each channel is allotted 200 kHz of 'elbow 
room', thereby permitting full expansion of all the 
sidebands without restriction. 

The f.m. system has attractive attributes over and 
above the a.m. system, including enhanced signal-to- 
noise performance, the ability to reject a.m. signals 
and interference and a parameter known as the 
'capture ratio'. 

The capture ratio stems from the nature of f.m. 
demodulation and from the amplitude limiting 
engineered into the i.f. channel of the receiver. It 
means that when two signals are present in the same 
channel (or close together in the receiver's passband) 
the weaker one is almost completely rejected and 
only the stronger of the two gives an output, free 
from interference. 

A capture ratio of two or three decibels ensures 
that a co-channel signal is muted when the wanted 
signal is only about lOdB above it. Nothing like this 
degree of rejection is possible on a.m. All this boils 
down to the fact that the f.m. radio system is truly 
hi-fi, and that a.m. cannot be regarded in this light 
at all. 

730 



DEVELOPMENTS 

Contemporary radio tuners and the tuner sections 
of tuner-amplifiers are fast taking in the latest 
devices, including field effect transistors (f.e.t's.), 
integrated circuits (i.c's.), crystal amd ceramic i.f. 
filters supplementing the bandpass transformer 
couplings. F.e.t's. are used mostly in the front-end as 
the r.f. amplifier and, sometimes, the mixer (with a 
bipolar local oscillator). Since their transfer charac- 
teristics exhibit second-order components they yield 
fewer third-order intermodulation components at 
high signal level than bipolar counterparts, whose 
characteristics contain an abundance of third-order 
components. 

This means that unwanted spurious signals are 
minimised, particularly at locations close to a 
powerful station group. They also provide other 
attributes, including relatively low noise working and 
good 'mixing' properties. Thus a tuner section (f.m.) 
containing an f.e.t. r.f. amplifier and an f.e.t. mixer is 
likely to out-perform an 'equivalent' incorporating 
bipolar devices in these stages under a wide range of 
operating conditions. 



THIRD ORDER INTERMODULATION 

One problem v/ith simple f.m. front-ends is third- 
order intermodulation when operated in a strong, 
locally derived signal field. One symptom of this is a 
spurious signal at Radio 3 frequency (from f*+f*— fs, 
where f>, £j and U are the frequencies of Radios 2, 
3 and 4 respectively). This can result in 'burbles' 
and similar sort of interference on Radio 3, and 
possibly 'birdies' inteference when Radio 3 is stereo 
encoded. 



R1 ^ 



•WAV 
R1 



; : "Live' 



Coaxial 

from 

ae r iai 

Braid 



R2 



'Earthy' 



Fig. 1: Simple attenuator for reducing intermodulation problems. 



SPECIAL PURCHASE! 

BRAND NEW FM MULTIPLEX STEREO DECODERS 

Manufactured by PHILIPS. Size 2"x3}"xl". 
All transistor 24v. at B inA. Supplied pre-aligned 
with lull circuit diagram and connection detials. 
£4 eaob Post Free 

LEAK MK I TRANSCRIPTION PICK-UP ARMS 
Using the world famous gimbal pivot system. 
Complete but less pick up head. £2-50 P. & P. 20p 
INPUT MATCHING TRANSFORMER 
Beautifully made in heavy Mu-metal cylindrical 
case for minimum hum pick-up. 8ize 11" highxl}" 
dia. Ratio 100 : 1 approx. Especially suitable for 
matching dynamlo or ribbon mikes or pick up from 
low to high impedance or vice versa. 76p each 
Poit Free 

BUCK ANODISED I 6k. ALUMINIUM HEAT SINKS 
For T03, complete with mica's * bushes. Size 
21" X 3" approx. 26p pair P. & P. 5p. 



HARVERSONIC SUPER SOUND 
10 + 10 STEREO AMPLIFIER KIT 




HEW IMPROVED MODEL WITH HIGHER OUT- 
PUT AND INCORPORATING HIGH QUALITY 
READY DRILLED PRINTED CIRCUIT BOARD FOR 
EASY CONSTRUCTION 



A really lirst-class Hi-Fi Stereo Amplifier Kit. Uses 14 
transistors including Silicon Transistors in the first five 
stages on each channel resulting in even lower noise 
level with Improved sensitivity. Integrated pre-amp with 
Bass, Treble and two Volume Controls. Suitable for use 
with Ceramic or Crystal cartridges. Output stage for any 
speakers from to 15 ohms. Compact design, all parts 
supplied including drilled metal work, high quality 
ready drilled printed eirouit board, attractive front panel, 
knobs, wire, solder, nuts, bolts — no extras to buy. 
Simple step by step Instructions enable any constructor 
to build an amplifier to be proud of. Brief specification; 
Power output: 14 watts r.m.s. per channel into 5 ohms. 
Frequency response ±3dB 12-30,000 Hz Sensitivity: 
better than 80mV Into 1MQ. Full power bandwidth: 
±3dB 12-15,000 Hz. Bass boost approx. to ±12dB. 
Treble cut approx. to - lHdB. Negative feedback 18dB 
over main amp. Power requirements 35v. at 1.0 amp. 
Overall Size 12"w. x 8"d. x 2|"b. 
Fully detailed 7 page construction manual and parts 
list free with kit or send 18p plus large S.A.E. 
PRICES 

AMPLIFIF.R KIT . . £10-50 P. 4 P. lop 

POWER PACK KIT .. £3-00 P. 4 P. SOp 

CABINET £3-00 P. 4 P. 30p 

(Post Free If all units purchased at same time) 
Full after sales service 
Also available ready built and tested £80-60. Post Free. 
Note: The above amplifier is tuitable for feeding (too mono 
sources into inputs {e .g. mike, radio, twin record decks, etc.) 
and will then provide mixing and fading facilities for med- 
ium powered Hi Fi Discothcgu 



SPECIAL PURCHASE OF MANUFACTURERS SURPLUS 1 
All Transistor F.M. tuner head with twin A.M. Gang 
incorporated. Beajtilully engineered with precision 
geared reduction drive. FM RF Transistor, oscillator/Mixer 
and first I.F. stage (10.7 Mc/s out- 
put) with optional APC connection. 
Built on printed circuit panel and 
fully screened. Extremely stable 
over range 88-108Mc/s. Brand new 
and pre-aligned. Size 2i"h x lj"w 
x 2i'd. For 6v D.C. at 2.8mA. 
A.M. Gang fitted with trimmers 
which can be connected to standard 
A.M. aerial and oscillator circuits 
if required. LIMITED NUMBER. 
Only £2.25 post free. Connection 
detail* supplied. 




HIGH GRADE COPPER LAMINATE BOARDS. 
8 X 6 x Ain. FIVE ior 50p. P. A p. I 3p. 
TELESCOPIC AERIALS WITH SWIVEL JOINT. Can 
be angled and rotated in any direction. 6 section Lacquered 
Brass. Extend" from Gin. to 22lin. approx. Maximum 
diameter }ln. 25p each. P. 4 P. Sp. 

BRAND NEW MULTI-RATIO MAINS TRANSFOR- 
MERS. Giving 13 alternatives. Primary: 0-210-240v. 
Secondary combinations 0-5-10-15-20-25-30-35-40-60V. 
hall wave at 1 amp. or 10-0-10, 20-0-20, 30-0-30v. at 
2 amps full wave. 8lz« 3ln. long X SJln. wide x 3in. deep. 
Price £1-75 P. 4 P. 30p. 

MAUIS TRANSFORMER. For transistor power supplies. 
Prl. 200/240v. Sec. 9-0-9 at 500mA. 70p. P. 4 P. 13p. 
Prl. 200/240V. Sec. 12-0-12 at 1 amp. 88p. P. 4 P 13p. 
Prl. 200/240V. 8eo. 10-0-10 at 2 amp. £1-38. P. A P. SOp. 
Tapped Primary 20O-22O-240v. Sec. 21.6v. at 500mA. 
63p. P. 4 P. 13p. 

4 AMP BATTERY CHARGER TRANSFORMER. Brand 
new. For 8 or 12v. 240v. Primary. Secondary volts rms 
off load lOv and 18-5v. Overall size approx. 2J' X 21' X 
3". Weight 31bs. Limited number at £1-35. P. 4 P. 35p. 



SPECIAL OFFER ! 

HI-FI LOUDSPEAKER SYSTEMS 

Beautifully made teak finish enclosure with most 
attractive Tygan-Uynalr front. Size 10j" high x 10J" 
widex 5 J" deep. Fitter with E.M.I. Ceramic Magnet 
13" x 8" bass unit, two H.F. tweeter units and 
crossover. Power handling 10 watts. Available 3 or 
8 or 15 ohms impedance. 

OUR PRICE £8.40 

Cabinet Available Separately £4-50 Carr OOp 

Also available in 8 ohms with EMI 13" x 8" bass 

speaker with parasitio tweeter £8-50 Carr. 65p 



LOUDSPEAKER BARGAINS 
5in. 3 ohm 80p, P. 4 P. 15p. 7 X 4in. 3 ohm £1-05, P. 4 P. 
20p, 10 X 6in. 3 or 15 ohm £1-80, P 4 P. 30p, E.M.I. 
8 x 5in. 3 ohm with high flux magnet £1.82, P. 4 P. 20p 
E.M.I. 13} x sin. 3 ohm with high flux ceramic magnet 
£8-10 (15 ohm £2-25), P- 4 P. 30p. E.M.I. 13 X 8in. 3, 8 
or 15 ohm with two inbuilt tweeters and crossover net- 
work £420. P. 4 P. 30p. E.M.I. IS X 8in. twin cone 
(parasitic tweeter) 8 ohm £2-25, P. 4 P. 30p. 
BRAND NEW. 12in. 15w. n/D Speakers, 3 or 15 ohms. 
Current production b y well-known British maker. Now 
with Hitlux ceramic ferrobar magnet assembly £5-50. 
Guitar models: 25w. £6-50, 35w. £8-50. P. 4 P. 38p 
E.HL SJin. HEAVY DUTY TWEETERS. Powerful 
ceramic magnet. Available in 3 or 8 or 15 ohms 93p 
each. P. 4 P. 13p. 

12in. "RA" TWIN CONE LOUDSPEAKER. 10 watts 
peak har.dling. 3, 8 or 15 ohm £2-20, P. A P. 30p. 
35 ohm SPEAKERS 3in. onl> 63p P. 4 P. 13p. 
VYNAIB & REXINE SPEAKERS & CABINET FABRICS 
app. 54 in. wide. Usually £1-76 yd., our price 75p yd. 
length. P. 4 P. 15p (ruin 1 yd.) S.A.E. for samples. 

SPEAKER CABINET BARGAIN 
Beautifully made all wooden construction medium walnut 
front, gold anodised expanded aluminium grille and dark 
sides. Approx. size overall 11 J" high x 6" deep X 131" 
wide at base. Baffle cut out for 8" speaker. Could accom- 
modate amplifier or radio together with speaker. 
FEW LEFT ONLY £1-38. Post Free. 

HI-FI STEREO HEADPHONES 

Adjustable headband with comfortable Ucxifoam ear- 
muffs. Wired and fitted with Btandard stereo Jin jack 
plug. Frequency response 3O-15.0O0Hz. Matching 
impedance 8-16 ohms. Easily converted for Mono. 
PRICE £2-95. P. 4 P. 15p 

SINGLE HEADPHONE. With aluminium headband. 
Approx. 200 ohm, 25p. P. 4 P. 8p 

CRYSTAL MIKES. High Imp. Ior desk or hand use. 
High sensitivity, 93p, P. 4 P. 8p 
HIGH IMPEDANCE CRYSTAL 6TICK MIKES. 
OUR PRICE £1-05. P. 4 P. 8p 



GENERAL PURPOSE HIGH STABILITY 
TRANSISTOR PRE-AMPLIFIER 
For P.U. Tape. Mike, Guitar, etc. and suitable for 
use with valve or transistor equipment. 9-18v. 
battery or from H.T. line 200/3C0v. Frequency 
response 15Hz- 25 KHz. Gain 26dB. Solid encap- 
sulation size 1|" x 1J" x I*. Brand new complete 
with instructions. Price 88 p. P. 4 P. 13p. 



BRAND NEW E.M.I. LIGHTWEIGHT PICK-UP ARM 
WITH ARM REST. Fitted mono t/o stylus and cartridge 
for LP/78. ONLY £ 1. P. 4 P. 13p. 

QUALITY RECORD PLAYER AMPLIFIER MK II 
A top quality record player amplifier employing heavy 
duty double wound mains transformer, ECC83, EL84, 
and rectifier. Separate Bass, Treble and Volume controls. 
Complete with output transformer matched for 3 ohm 
speaker. Size 7 in. wide x 31n. deep x t'.in. high. Ready 
built and tested. PRICE £8-75 P. 4 P. 40p 
ALSO AVAILABLE mounted on board with output 
transformer and speaker ready to fit into cabinet below. 
PRICE £4-88 P. 4 P. 60p. 

DELUXE QUALITY PORTABLE R/P CABINET MK H. 
Uncut motor board size 14i X 12ln. clearance 2ln. below. 
5 T in. above. Will take above amplifier and any B.S.B. or 
GARRARD changer or Single Player (except AT60 and 
SP25). Size 18 X 15 X 8ln. PRICE £4-75, P. 4 P. 60p. 



10/14 WATT HUFI AMPLIFIER KIT 



A stylishly finished 
monaural amplifier 
with an output of 
14 watts from 3 
EL84s in push-pull. 
Super reproduction 
of both music and 
speech, with negli- 
gible hum. Separate 
inputs for mike and 
gram allow records 
and announcements 
to follow each other. 
Fully shrouded section wound output transformer to 
match 3-16 CI speaker and 2 independent volume controls, 
and separate base and treble controls are provided 
giving good lift and cut. Valve line-up 2 EL84S, ECC83, 
EF88 and EZ80 rectifier. Simple instruction booklet 
13p (Free with parts). All parti iold separately. ONLY 
£7-97 P. 4 P. 55p. Also available readv built and tested 
complete with std. input sockets, £9-97. P. 4 P. 55p. 




FANTASTIC 'POLY PLANAR' WAFER-TYPE, 
WIDE RANGE ELECTRC-DYNAMIC SPEAKER 
Size only 11}" X 14)1" x 1ft" deep. Weight only 

19 oza. Can replace cone speakers In any application 
and is particularly useful for those with limited 
space. Extremely rugged and shockprool. Operating 
temperature — 20°F to +176°F. Power handling 

20 watts rms (40 watts peak). Impedance 8 ohm 
only. Response 40 Hz — 20 KHz. Can be mounted 
on ceilings, walls, doors, under tables, etc. and 
used with or without baffle. Send S.A.E. for full 
details. Only £5-75 each. P 4 P. 26p. 



DE LUXE STEREO AMPLIFIER 




smoothing 
with negli- 
gible hum. 

Valve line op:— 2 x ECL86 Trlode Pentodes. 1 x F.S580 
as rectifier. Two dual potentiometers are provided for 
bass and treble control, giving bass and treble boost and 
cut. A dual volume control is used. Balance of the left and 
right hand channels can be adjusted by means of a sepa- 
rate 'Balance' control fitted at the rear of the chassis. 
Input sensitivity is approximately 300ro/v for full peak 
output of 4 watts per channel (8 watts mono), into 3 ohm 
speakers. Full negative feedback in a carefully calculated 
circuit, allows high volume levels to be ubci! with negligible 
distortion. Supplied complete with knobs, chassis size 
ll"w x 4"d. Overall height Including valves 5". Ready 
built 4 tested to a high standard. PRICE £8-92 P.4P. 4Sp. 

4-SPEED RECORD PLAYER BARGAHJS 
Mains models. All brand new in maker'! packing. 
LATEST B.S.R. C109/A21 4-SPEED AUTOCHANGER 
With latest mono compatible cartridge £6-97 Carr. 50p. 
With stereo cartridge £7 -97 Carr. OOp. 
SUITABLE PLINTH UNIT FOR ABOVE with rigid plastic 
cover. £5-75 complete P. 4 P. SOp. 

LATEST GARRARD MODELS. All types available 1025. 
2025, SP25, 3000, AT80 etc S.A.E. Ior latest Prices' 
PLINTH UNITS cut out for Garrard Models. 1025. 2025» 
2000. 3000, 3500 etc. With rigid transparent plastic cover. 
Special design enables above models to be used with cover 
in position. Also suitable for housing AT80 and SP25. 
OUR PRICE £5.75 complete. P. 4 P. 50p. 

LATEST ACOS GP91/1SC mono compatible cartnilRe with 
t/o stvius for LP/EP/78. Universal mounting bracket. 
£1-50 P. 4 P. 8p. 

SONOTONESTAHC COMPATIBLE STEREO CARTRIDGE 
T/O stylus Diamond Stereo LP and Sapphire 78. 
ONLY £2-50 P. 4 P. lOp. Also available fitted with twin 
Diamond T/O stylus for Stereo LP. £3. P. 4 P. lOp. 
LATEST RONETTE T/O STEREO COMPATIBLE 
CARTRIDGE lor EP/LP/8tereo/78. £1-88 P. 4 P. lOp. 
LATEST RONETTE T/O MONO COMPATIBLE CART- 
RIDGE for playing EP/LP/78 mono or stereo records 
on mono equipment. Only £1-50 P. 4 P. lOp. 




8-VALVE AUDIO 
AMPLIFIER HA34 MK II. 
Designed for Hi-Fi reproduc- 
tion of records. A.C. Mains 
operation. Ready built on 
plated heavy gauge metal 
chassis, size 7t" w. x 4" d. X 
4|" h. Incorporates ECC83, 
EL84, EZ80 valves. Heavy 
duty, double wound mains 
transformer and output trans- 
former matched for 3 ohm 
speaker. Separate volume control and now with Improved 
wide range tone controls giving bass and treble lift and 
cut. Negative feedback line. Output 4 l watts. Front 
panel can be detached and leads extended for remote 
mounting of controls. Complete with knobs, valves, etc., 
wired and tested for only £4-75. P. 4 P. 35p. 
HSL "FOUR" AMPLIFIER KPT. Similar in appearance 
to HA34 above but employs entirely different and 
advanced circuitry. Complete set of parts, etc. £3-98. 
P. 4 P. 40p. 

HARVERSON'S SUPER MONO AMPLIFIER 
A super quality gram amplifier using a double wound fully 
isolated mains transformer, rectifier and ECL82 trlode 
pentode valve as audio amplifier and power output 
stage. Impedance 3 ohms. Output approx. 3.5 watts. 
Volume and tone controls. Chassis size only 71n. wide 
X Sin. deep x 6in. high overall. AC mains 200/240v. 
Supplied absolutely Brand New completely wired and 
tested with good quality output transformer. 
FEW ONLY. {") TfC P. 4 P. 



BARGAIN PRICE 



Sop 



HANDBO OK O F TRANSIS TOR 

EQUIVALENTS AND SUBSTITUTES 

A must for servicemen and home constructors. 

1971 edition including many 1000's of British, 

U.S.A., European and Japanese transistors. 

ONLY 40pPost5p. 



Open 9-5.30 Monday to 
Saturday 

Early closing Wad. I p.m. 

A few minutes from South Wtmbls- 
ion Tube Station. 



HARVERSON SURPLUS CO. LTD. 

170 HIGH ST., MERTON. LONDON, S.W.I9 Tel.: 01-540 3985 

SEND STAMPED ADDRESSED ENVELOPE WITH ALL ENQUIRIES 



(Please write clearly) 

PLEASE NOTE: P. * P. 
CHARGES QUOTED APPLY 
TO U.K. ONLY. P. & P. OH 
OVERSEAS ORDERS CHARGED 
EXTRA. 



731 



BENTLEY ACOUSTIC 
CORPORATION LTD. 

36 CHALCOT ROAD, CHALK FARM, LONDON. N.W.I 
THE VALVE SPECIALISTS Telephone 0l-722-M»0 



OA2 .80 

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All v«lvc» are amino!, boxed, and subject to the standard 90 day guarantee. Term* uf bunlneu — 
Cash or cheque with order only. Post/jKicking 3p. per lt«m. "iibject tn a minimum of 9p. per order 
Order, over £5.00 post/packing h-ee. 8ame day despatch l.v flr»t cla." mall. Any parcel insured 
against damage in transit for only 3p. extra per order. Complete catalogue with condition* of sale 
price 7p. post paid. Business hours Mon.-Fri. 9-3.30 p.m. Sat». 9-1 p.m. 

""-do not handle seconds nor rejects, which are often described as "Sew and Tested" but ha»e a 
iled ami unreliable life. So enquires answered unless 8.A.E. is enclosed for replv. 




PHOTOELECTRIC KIT 

CONTENTS. 2 P.O. Chassis Boards, Chemicals. Etching Manual. Infra-Red Photo- 
transistor, I-atching Relay. 2 Transistors. 3 Diodes, Resistors, (iain Control, Terminal 
Block, Elegant Case, Screws, etc. In fact everything you need to build a Steadv-I.ight 
Photo-8wltch/Counter/Burgl.-.r Mann. etc. (Project S... I) which can be modified for 

:li^Q© PHOTOELECTRIC KIT 
£2.60 

c.-iage and Pack. 15p (UK) 

Commonwealth : 

SURFACE MAIL 25ii 

AIR MAIL £1.40 

Australia, New Zealand. 

5. Africa, Canada and U.S.A. 

Mso Essential Data Circuits 

and Plans for Building 

10 Advanced Designs 

INVIS8LE BEAM OPTICAL KIT 

Everything needed (except plywood) for budding: I Invisible- Beam Projector and I 
Photocell Receiver (as illustrated). Suitable for all Photoelectric Burglar Alarms, 
Counters, Door Openers, etc. 

CONTENTS: 2 lenses, 2 mirrors, 2 45-degree wooden blocks. Infra-red filter, pro- 
jector lamp holder, building plans, etc. Price 81.25 Postage and Pack. lOp (U.K.) 
Commonwealth : Surface Mall 20p, Air Mail 50p. 

LONG RANGE INVISBLE BEAM OPTICAL KIT 

CONTENTS: As above. Twice the range of standard kit. Larger Lenses, Filter, etc. 
Price 1 1.86. Postage and Pack 16p (U.K.) Commonwealth: Surface Mail 20p. Air Mail 

JUNIOR PHOTOELECTRIC KIT 

% ersatlle Invisible-beam. Relay-less, Steady-light Photo-Switch, Burglar Alarm, Door 
Opener. Counter, etc.. for the Experimenter. 

CONTENTS : Infra-Red Bensit Ive Phototransistor. 3 Transistors, Chassis, Plastic Case. 
Resistors. Screws, etc. Full 8i« Plans, Instructions, Data Sheet "10 Advanced Photo- 
electric Designs". 
Price 81.85. Postage and Pack. lOp (U.K.). Commonwealth 20p: Airmail BOp. 

JUNIOR OPTICAL KIT 

OONTENT8 : 2 Lenses, Infra-red Filter. Landholder, Bracket, Plans, etc Everything 
(except plywood) to build 1 miniature invisible beam projector and photocell receiver 
for use with Junior Photoelectric Kit. 
Price ?Sp. Post, and Pack. lOp (U.K.). Commonwealth: 8urface Mail 20p: Air Mali 50p. 

YORK ELECTRICS Mail Order Dept. 

335 BATTERSEA PARK RD., LONDON S.W.11 

Send S.A.E. Jot full detail*, a brief deieriptim of all Kill and ProjreU 



BAKER I2in. REGENT 

An inexpensive unit for the beginner in 
high fidelity and for general purposes. May 
be used to advantage with any Radio, 
Amplifier or Television receiver. 
Maximum Power 15 watts 
Bass Resonance 45 c.p.s. 

Flux Density 12, 000 gauss 
Voice Coil impedance 

3 or S or IS ohm models 
Useful response 

45-1:1,000 cp.s. 

Nett weight 5 lbs. 

GUITAR MODEL "GROUP 25 

25 watt rating 

Latest catalogue S s with enclosure plant. 



laker Reproducers. Ltd 




Bcnsham Manor Road Passage, Thornton Heath, Surrey. 0I-6M-I665 



UNBEATABLE 

RUSSIAN 

VALUE 




TECHNICAL DATA : 
Waveband 1 frequency 1 
LW 2000 — 735-5I1.. 
MW 571-4— I86B111 
BW3 631— 40-54DI 
8W2 31-91— 24-79711 
8W1 19-87—18-76111 
VHF 3-43— 288m 

(5—104 mc/s) 
17 translHtorx, 8 diodes 
Send or call at:- 



SOLAR OF 1972 

PERFORMANCE CAN BE COMPARED WITH £66 RADIOS! 
Sockets lor tape recorder, record player, extension speaker. 
earphone, external power supply (12v DC), external line and 
dlpole aerials. Battery life approx. 800 boon. 
At last, the Astrad Solar Radio combining quality with value 
and a apeclflcatioii not before available front Russia. 
Designed for the man who appreciates the extra* neceasary 
lor quality performance. Thih 6 waveband Radio ban twin 
opeakers for quality. Fully independent Treble and Basx 
tone contrnlH for ultimate performance and twin separate 
tuning control* for AM A FM broadcasts. 12 push button* 
for waveband election including automatic frequency con- 
trol on VHF. This Ut the big set from Russia, overall dimen- 
sions — 14* x 91" x 41". Included In this Incredible speci- 
fication is an Inbuilt tuning meter to ensure that you are 
spot-on the station you select. Telescopic aerial on universal 
joint and a push-button dial light. All presented in a 
wooden teak case with carrying handle. This fabulous 
Radio is fully guaranteed for 1 year. 



£26-97 



8U2 sealed batteries 60p. 
Earphones lOp. P. A F. 7 



8EBA ELECTRONICS. Dept. M/0. 104 Uxbridge Boad. Hanwell. London. W7. 
Phone: 01-678 6644 



732 



AGC 




Fig. 2: Circuit of the "front-end" of a typical British tuner-amplifier. 




68 
OVW 
504 

With 5*iV In at 100MHz -4V cB 

II 5QMV H -4V c*a 

M 50Q»JV ii -5-6V da 

il 5mV ll -8-6V rta 



AA/VW-o 

510 

-15V 



ii 50mV ii 



-9-6V ct> 



Voltages marked a=> measured with a valve voltmeter (Z in > 10MQ.) 
Voltages measured with no signal Input except where stated 



Fig. 3: The f.m. i.f. channel of the tuner -amplifier shown above. 



733 



One solution lies in attenuating the signal from the 
aerial to the set. Belling Lee make plug-in attenuators 
over a range of values; alternatively a simple resis- 
tive pad can be made up as shown in Fig. 1. 

FM FRONT-END 

The f.m. front-end of a typical British tuner- 
amplifier is shown in Fig. 2. Here VT1 is a dual-gate 
f.e.t. with the input signal applied to one gate and an 
a.g.c. potential to the other. The mixer is bipolar 
VT2 and the local oscillator bipolar VT3. 

Aerial coupling is by Tl primary, and since this is 
centre-tapped 300 ohms balanced feeder can be 
connected across terminals 1-2 or 75 ohms coaxial 
(unbalanced) across 2-3. Not all input circuits permit 
this dual mode of feeder connection, and if the 
design is essentially for 300 ohms balanced (or 
240 ohms European DIN) the best coupling from 
coaxial is obtained through a 'balun' transformer. 

A.f.c. is applied to the local oscillator from a 
varactor diode (MB601), and this receives its control 
bias from the f.m. detector. The varactor is in 
parallel with the oscillator tuned circuit, so the 
frequency of this is altered by the control bias which 
appears in appropriate polarity from the f.m. 
detector when the tuned carrier is displaced from the 
centre of the i.f. passband. 

The i.f. signal is developed across T2, and is 
coupled to the f.m. i.f. channel from the capacitance 
tap on circuit No. 8. 

FM IF CHANNEL 

The f.m. i.f. channel is shown in Fig. 3, and the 
input goes to circuit No. 503 and thence to the base 
of VT501. 

The channel includes two ceramic filters of the 
kind already mentioned (X501/X502) and a couple 
of i.c's. (VT503/VT504). The ceramic filters take the 
place of the usual i.f. transformers and because they 
exhibit steeply rising and falling response sides 
extremely good i.f. selectivity is secured. The only 
alignment required is of the ratio detector trans- 
former T501. 

The i.f. signal at VT501 collector is fed to the first 
filter and from this to the first i.e. The second filter 
couples the two i.c's., while VT505 bipolar transistor 
drives the ratio detector, composed of diodes D1/D2, 
etc. This circuit is balanced, and preset BV501 
allows this to be optimised, one mode for adjustment 
being for the least response to an a.m. signal. 

It will be noticed that the ratio detector yields 
potential for the tuning meter as well as for the 
varactor diode on circuits 506 and 505 respectively. 
Demodulated audio (or multiplex signal in the case 
of stereo) from circuit 507 is coupled to the stereo 
decoder. 

VT506 is concerned with the muting, etc., while 
VT502 amplifies i.f. signal at VT501 collector and 
passes it to the rectifier MB501. The resulting filtered 
d.c. constitutes the a.g.c. potential for the f.e.t. r.f. 
amplifier (Fig. 2). 

FAULT FINDING 

Fault finding in a circuit of this kind is best carried 
out by feeding a modulated 10-7MHz (or a signal at 
the i.f. ) into the strip, starting at the final transistor 
(VT505 in this case), then working forward until the 
point of inactivity is located. 

734 



To find the actual component which is in trouble, 
after locating the faulty area or stage, might well 
require the testing of voltages, etc. at the electrodes 
of the various devices, and to help in this respect the 
voltage references in Fig. 3 have been retained. 

Servicing of f.m. front-ends is not recommended 
— apart, possibly, from the replacement of transistors 
— and trouble in this area is best left to the maker 
or distributor to clear. This applies to professional 
service organisations as well as to the amateur 
repairer. 

A word about the replacement of f.e.t's. would not 
be amiss. The insulated gate types in particular are 
vulnerable to static discharges, and when making a 
replacement always retain the shorting clip (fitted by 
the maker) until the device has been completely 
soldered into the circuit. 

From the testing, adjusting and servicing aspects, 
the BBC's stereo test sequence at the close-down of 
Radio 3 can be of a great help in determining such 
parameters as stereo separation (e.g., degree of 
crosstalk), signal-to-noise, frequency response, etc. 

SOURCE INPUTS 

When a radio tuner is used with a hi-fi amplifier a 
'flat' response is required since the de-emphasis is 
performed in the tuner. Inputs with 'flat' responses 
thus include radio, high-level tape replay and 
auxiliary. If an amplifier is equipped with an input 
for the signal direct from a tape head, then equalisa- 
tion will be included to cater for the replay response. 
The only equal: sing then required is that pertaining 
to the gramophone pickup, and a good starting point 
is the pickup (cartridge) itself. 

PICKUPS 

There are two versions. One the magnetic which 
works rather like a generator, and the piezo, using 
either a natural crystal or processed ceramic, which 
works on the transducer principle. 

When a gramophone record is made the modula- 
tion is imparted to the groove from a cutting head 
via a special electrical filter having a specific 











15 

10 

5 

dS O 

-5 

-10 

-15 

-20 


















\S 


















■■ 


A 
















/ 














:. 


yS 


* 






























'1 














■ ]' 












i 




















i 






S6 SO 10O 200 500 
Frequeno 


KOO 2k 5k 
in Hz 


&20k 





Fig. 4: Graph showing the standard RIAA recording characteristic 

recording characteristic. The bass end of the 
spectrum is attenuated and the treble end is boosted. 
On replay, therefore, the bass needs to be boosted 
and the treble attenuated to secure a 'flat' audio 
output. 

The standard recording characteristic is given in 
Fig. 4. This ha:; an 'average' slope of about 4dB/ 



THIS MONTH'S 
SPECIAL 

BARGAINS 



SINCLAIR 2-30 £3 95. 250 £4-29. PZ5 £4 40 
Mleromatlc Kit £2-25. Mleromatlc Built £2 75 
PZ6£»-95, PZ7£5 95. PZ8 £6 95. AFU £5 25 
Stereo 80 CI'H, Prospect 60 FM Tuner £20 90 

AUTOCHANGERS BSR UA25 dual mono 
cart. £1-95. De luxe Portable R/P cabinet. 
Blue. at*. £7-95 THE PAIR. GARRARD 
ARTS £15 99, 3000 £1 95. 3500 £8-95. 1025 
W/GKS26 SC. Cart. £8-50. 

MAGNETIC CARTS AT55 Latest Audio 
Technics £4-75. AT35 Super HI Fl £11 90, 
PIEZO Oe Luxe £4-50. 

RECORD PLAYERS "HOB PARTY" 

German Transistor Portable 33/45 RPM. 
Small But Superior £7 90. SEAFIRLE Teak 
De Luxe Garrard Deck. Base Treble Con- 
rols (Portable Worth £32) £1900. 

STEREO TUNER AMPS General R4200 
(List £51-15) £29 50. Teleton 7 AT1 FAN- 
TASTIC PERFORMANCE £69 00. Teleton 
10AT1 (List Approx. £150) 100W RMS 
Total FET (DEM Models) Guaranteed £85. 

STP800 8-TRACK TAPE PLAYER Stereo 
background music. Teleton complete In 
"Rosewood" plinth with matching /lO 
speakers (List Approx. £50) "■*» 

CMS400 TUNER-AMP.PLAYER Tellton 
complete with stereo decoder perspex Tod 
(requiring only speakers to make £69 

complete system). Amazing value ■*•» 

COMPLETE STEREO SYSTEMS Sharo 
STA11 MW/FM/Multlplex stereo tuner AMP 
F.E.T. Front end 27 transistors 10W+10W 
Max O.P. Requiring only record deck to 
complete (List ADprox. £85) £69. FUJI com- 
plete system STS-BLTL similar to above 
but comolete with built In reload deck, snip 

-£59 

TAPE DECKS Teleton FXB510D Stereo 
(List £65) tew only at £45. BSR TD2 Standard 
2 track decks with 2 tone top plate £7 50 

AMSTRAD 8900 Stereo plinth 7w+7w 
R.M.S. Mag.'Cer/Tape /IQ.CA 
(List £26) * ' T av 

LOUDSPEAKERS CHASSIS EMI 13" X 

8" 10,000 line, 10 watts R.M.S. In 30, Hi W 
ISO £1-65, two for £2-95. EMI 13" x 8" 150 
units with concentric tweeter cone CI -85. 
O for £3-50 



jasan 

SawW mmmmmmmmmmmm * its 



FANTASTICALLY POPULAR 

• TAPE • 

We oSer roo tally tensflised polyester/mylar 
and F.Y.C tapes ol identical quality bi-tl. wide 
nose recording characteristics as top grade 
tapes. Quality control manufacture. They are 
Italy worth a lew more coppers than acetate, 
sob-standard. Jointed or cheap Imports. 
IRT 0HB AHD PROVE IT YOURSELF. 



j a son 



Introducing The New 

"ALPHA" Loudspeaker Enclosure. 

Incorporating the lamooa EMI "450" set consisting ol a 
13x8in. bass unit with a high flax ceramic magnet, 2 
tweeters and eroasorer. 20 watt peak handling power (10 
watts BUS). 

Heavy duty 18mm infinite baffle case in ropers quality genuine 
golden teak Tensers with solid mahogany contrasting leading 
edges. High quality loam loaded cloth bet Acoustically 
loaded "Jason" rotating badge in guanine gold leal tor 
horizontal or vertical operation. Siie IBin.xlOin.xlO.'in. 
Weight 18!bs. A price break through at only 
Carriage etc. 50p lingly. Jp 1 O ■ ■» fl each 

Carriage lree in pairs. Ow I efc tJU 

JASON SEWOR SOW EH0LOSURE. As above but with 
taper hesvy duty bass nnit with 3 61b magnet in Hagnaduer 
II material with 1-Wn speech coll and super tweeter 
giving Ireqnency range ol 20 -20,000Hz. Standard 8(1 impedance in beautifully 
finished heavy teak veneers. Size 12Jxl2xB8in. 20 Watts EMS, 40 watts peak. 

At a super keen price 




£18 



& 3 C s pair carriage^ and ins. 



62|p lor 1 or 2. 



PLINTHS & COVERS lor Canard (all take current models except 
heavy transcription types) Beautilul heavy solid peripex top with "stereo" badge high 
quality base with solid wood sides machined ready lor B/P deck to drop in without 
lerrinfvalu^onb £3-75 complete. C«r. & Insurance 40p. 



KG-620 4i' VTVM KIT * NEW! 

SPECIFICATIONS 



Standard Play 



Sin. ISOtt. 
tin. 300ft. 
5in. flOOtt. 
6tln. 900ft. 
71n. 1,200ft. 

Double I 
Sin. SOOft. 
4in. 600ft. 
Sra. 1.200ft. 
5|in. 1,800ft. 
7in. 2,400ft. 



12p 
22tP 
4fip 
58p 
62ip 

"SO, 

40p 

75p 

96p 

CS5 



Long Play 
Sin. 225ft. 
4in. 450ft. 
Sin. 900ft. 
5!in. 1,200ft. 
7in. 1.800ft. 



13p 
27p 
52(p 
65p 

02iP 




Ranges: 0-1- 5-6-I5-SO-I50-600- 

1,501 V lull icole; with optional 

High- Voltage Probe, to 25,000 V. 

Accuracy: ±3% Of full Kale 

reading. 

Input Beststance: 7' megohmi 

(7 meg In probe) up to 1.600V. 

Ranges (rms): 0-1- 5-5- 1 5-50- 

150-500- 1, 590V full Kale ip-p); 

V -42 ■ 14 -42 -140- 420- 1.4011 - 

4.200V full icale. 

Decibels: -10 to +85 In T 

ranget. 



Rerponse: ±ldB. 30Bx to 

3 3111:: ±3&B, 30Bz to 531/1:: 
Kith optional B.F. Probe, to 
260MBz. 

Aceuraoy: ±5% of full uale 
reading. 

Ranges: o-i,ooo-io,ooo-ioo,ooo 
ohmt; 0-1-UI-100-1,000 meg- 
ohm*. 
Centre Scales: 10. 100. 1,000. 

10,000, 100,0110 ohm': 1 end 10 

tnegohme. 

Battery: 1\V tize V2. 



Recommended Lilt 
Price £18-27t: 



£9-95 



ajacalM 

Price 



£12-90 



(Dp 

Price £30! 



KG-865 50 Watt Stereo Amplifier Chassis 



DE-LUXE FEATURES 

All Silicon Transistors lor Sta- 
bility. Cleaner 8ound4)Extremely 
Wide Power Bandwidth and 
Frequency Response #50 W IMF 
Power 0utput#8pecially Selec- 
ted Low-Noise Pream Transistor! 
•Two Printed Circuit Boards 
lor Fast Easy Assembly#Con- 
venlent Front-Panel Stereo Head- 
phone Track 4>Teak-nnished Ex- 
truded Aluminium Front Panel • 
Two a.c. Convenience Outlets. 




Output: SOW IHF, 25W per channel; 34W 
eoHlinuoui tine «-aw ©Response: ±ldB. U to 
3ii. mm in f>Gutput Impedances: 4 through 16 ohmt, 
plui itereo heodphoneitflM Distortion: under 1% 
at 60 II: and 7.000Hz mixed 4 : 1 at rated power 
#Input Senslttvlty. Magnetic Phono, SmV; 
Tuner and Auxiliary, .509ntK4JPower Require- 
ment: 230-250 V. SOHz a.c. Bee. List £C4J .fjft 

c*nt\ Price *«" w 

Our Price £29 



THIS MONTH'S 
SPECIAL 

BARGAINS 



BARGAIN PARCELS 

Including variable condensers l.f. colls, 
loudspeakers plug/sockets, knobs, con- 
densers, resistors, nuts, bolts, cabinet 
fittings, switches, transformer, choke, 
rectifier transistors at a small fraction of 
list value. Due to heavy demand we now 
pack them In aeveral sizes— be amazed- 
try one now. 

3lbs (post 24p) SOp 

7lbs (post 35p) 90p 

14lbs (post 45p) £1-66 

100 MIXED RESISTORS Wide range, all 
good values iW-2 Watt 35p, 200 for 65p, 
500 for £1-40. 

100 MIXED CONDENSERS Ceramic, Poly- 
ester, Silver Mica, Paper. Approx. 50 useful 
sizes 49p. 200 lor 85p, 500 for £1-95. 

100 MIXED HI-STADS Instrument types 
1% to 5%, big selection 4£q 

100 MINIATURE HIGH STADS Wide 
range of good values CQn 

25 MIXED POTS L/SW W/SW Preset 
Tandem, snip at Cflrj 

CHARGERS A|ax 6A12V 4amp with meter 
£1 95, Elplco 12V 1A (No Meter) £1 20. 

CAR AERIALS Give away prices, chromed 
panose fully retractable lock down (2 keys) 
44" overall 40° swivel (usually approx. £2-50) 
95p, 2 for fit -SO. Ditto semi-retractable 54" 
(Value £1-75) 65p, 2 for £1 20. 

CASSETTE RECORDERS Crown 

CTR320W Malns/BAR (List £33-40) £29, 
CTR9001 (List £28) £24 80, CTR9700 (List 

*»•»> £21-90 

STEREO HEADSETS SH650 Hosaidew 
large soft pada £2 45. Latest SDH-7DJ 
Black padded finish Vol Controls Mon. 
Stereo switch (Worth £10) £5-90. 

TV MAINS-BATT. PORTABLE Eliza- 
bethan dark screen TW1Z, UHF with aerial 
Black/Chrome finish (List £72-50) £56. 
Ditto Teleton TX12 (List £70) £55. Ditto 
Sharp (List £77) £59. 

AMPLIFIERS 300 ni.w. transistor model 
4-300 9V (DCORAC) P/P output 3-8 & 1-10 
m.v. sensitivity with vol control, size i" x 
11" x 5 T "£1-40. 



KG-375 Deluxe Solid-State Auto Analyser 



Tune-up and troubie-thoot any cat, 

perform actual road tciti 
I ft metal tettert in one . . .do all Ihii 

Bet Engine Idle and Automatic Trans- 
mission Shitt Points ODetect Condittor 
ol Point 8urtacei#Detect Distributor 
WeartjYCheck Voltage and Current 
RegulatorsSJCheck Generators lor 
both Current and Voltage Outputs* 
Find Poor or Open Earth Circuits* 
Detect Variation in Dwell Angle. 

Recommended f\7 
List Price ■""" 



£19 




NEW BRANCHES 

NOW OPEN AT 

"WEST SUSSEX 
HI-FI CENTRE" 

* QUEEN STREET * 

ARUNDEL 
TEL. ARUNDEL 882299 

"SOUTHAMPTON 
HI-FI CENTRE" 

* 77 EAST STREET * 

SOUTHAMPTON 
TEL. S'OTON. 25851 



Triple Play 
tin. OOOft. 86p 

5in. 1.800ft. n-lM 

5 (in. -.'.,400ft. £170 
71n. 3,600ft. 48-40 

Quadruple Play 
8m. 800ft. 42»P 



Postage 5p reel. 

Post Free less 5% on three reels. 
Quantity and Trade enquiries Invited. 
NOTE. Large tape itockt at all branches. 



tww*^^K»ft»:«a«at mm SKsSJ-wSsSSsa 



ECHNICAL 
WADING 



Psrk Crescent Place. 

Tel. 880722 



• BRIGHTON 

• PORTSMOUTH RgBr*** 

• SOUTHAMPTON SST 

• ARUNDEL 



16-17 Queen Street. 
Tel. 882299 



-*- All Hail Orders to ABtTHDEL, SUSSEX with names sod 
addresses in BLOCK CAPITALS please. 



735 



HENRY'S 

BY ATES EMIHUS 



FOR 
LOW COST 



FIRST GRADE •%&> BRANDED SITetVz^ks. bk, DGE s 



FAIRCHILD 



NEW 
FERRANTI 



SILICON TRANSISTORS, DIODES, RECTIFIERS, 
nd INTEGRATED CIRCUITS 

I.T.T. • MULLARD NEWMARKET PHILIPS ■ R.C.A. ■ TEXAS 



TRANSISTORS 

A SELECTION FROM OUR LIST 



AAT30 lOp 
AAY42 ISp 
AAZ13 lOp 
AAZ1S 10* 
AAZ17 lOp 
AC107 86p 
AC128 30p 
AC127 26p 
AC127Z 60p 
AC 128 20p 
AC176 SOp 
AC187 
AC188 
ACY17 80p 
ACT! 8 up 
ACY19 Up 
ACT20 BOp 
ACY21 SOp 
ACY22 lOp 
ACY39 Up 
ACY40 SOp 
ACY4I 16p 
ACY44 Up 
AD140 50p 
AD149 50p 
AD161 
AD162 
API 14 
AF113 
AF118 
AF1I7 
AFI18 
AF124 
AF125 
AF126 
AF127 
AF139 
AF180 
AF181 
AF185 
AF186 
AF239 



76p 
Si, 
BOp 
75p 
80p 



35p 
35p 
25p 
25 p 
25p 
2 Op 
80p 
25p 
20p 
20p 
20p 
30p 
50p 
45p 
60p 
40p 
40p 



A8Y26 Sop 
80p 



A8Y27 
A8Y28 Up 
A8Y29 80p 
ASZ21 Up 
BA100 ISp 
BA102 SOp 
BA110 Up 
BA115 7p 
BAX13 6p 
BAX16 7p 
BAY31 7p 
BAY38 ISp 
BC107 lOp 
BC108 lOp 
BC109 lOp 
BC109C 12p 
BO II 3 lOp 
BC114 SOp 
BC115 20p 
BC116 SOp 
BC116A Up 
BCU7 80p 
BC118 
BC119 
BC134 
BC135 
BC136 
BC137 
BC138 
BC147 
BCI48 
BC149 
BC153 
BC154 
BC167 
BC169 
BC169C 15p 
BC177 20p 
BC178 20p 
BC179 20 p 
BC182L lOp 
BC183L lOp 
BC184L ISp 
BC212L 18p 
BC213L 18p 
BC214L ISp 
BCY30 Up 
BCY31 40p 
BCY32 60p 
BCY33 SOp 
BCY34 3Sp 
BCY38 4Bp 
BCY39 

£1 00 
BCY40 BOp 
BCY70 15p 
BCY71 SOp 
BCY72 15p 



20p 
30p 
20p 

Up 

SOp 
20p 
20p 
12p 
lOp 
I2P 
20p 
2 Op 
;5p 
12p 



BD115 
BD123 
BD124 
BD131 
BD132 
BDY11 

£1 50 
BDY17 

1180 
BDY38 Up 
BDY90 

1100 



BF115 
BF1S4 
BF188 
BF159 
BF180 
BF194 
BF198 
BF196 
BF197 
BFX13 Up 
BFX29 UP 
BFX30 Up 
BFX84 Up 
BFX8S SOp 
BFX88 Up 
BFX87 UP 
BFX88 SOp 
BFY18 UP 
BFY5D SOp 
BFYB1 SOp 
BFYS2 SOp 
BFY53 ISp 
BFY90 UP 
B8X20 ISP 
B8X21 SOp 
B8Y27 ISp 
B8T95A ISp 
BBY95 ISp 
BV ) 05 £2 25 
BY1Q0 ISp 
BY12S Up 
BY124 ISp 
BY182 90p 
BYZ10 Up 
BY/. 11 SOp 
BYZ12 SOp 
BYZ13 Up 
BZY7811 00 
GET 102 Up 
OET103 Up 
GET111 ISp 
GET113 Up 
GF.T114 SOp 
GET 115 SOp 
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GET880 4Sp 
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OEX66 

11 SO 
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MAT121 Up 
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HJ420 SOp 
MJ421 80s 
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U10 
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MJE370 SOp 
UJE371 80p 
MJE520 75p 
MJES21 70p 
MJE2955 

£1 10 
MJE3058 

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MP8A56 80p 
MPSA70 ISp 
MP8UM SOp 
MP81'5A Up 
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XKT216Up 
XKT403 75p 
NKT404 66P 
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<><:■-•■'. 

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rut prteM 

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7400 Quadruple 2-lnpat NAM) gatea 80p 18p 

7401 Quid 2-input open collector XAXD gate* SOp ISp 

7408 Quad 2-input NOR iratee SOp 18p 

7408 Quad 2-lnput open collector XAXD gates . . SOp 18p 

7404 Hextupli- Inverters SOp Up 

7406 Hex Invertera with open collector output" . . BOp 18p 

7410 Triple 3-input NAXD galea BOp 18p 

7418 Dual 4-lnput Schmltt triggers SOp 87p 

7420 Dual 4-lnput XAXD gate* SOp Up 

7480 Single 8-lnput NAXD gate* SOp Up 

7440 Dual 4-input XAXD buffer gates BOp ISp 

7*41 BCD-Decimal decoder/Nlxle driver 7Sp 78p 

7442 BCD-Decimal decoder (410-llne) TTL O/P . . 75p 78p 

7448 Exceaa 3-Declmal decoder TTL outputs .. £100 Up 

7447 BCD-Decimal 7 aeg. decoder /indicator driver 11-00 Up 

7448 BCD-Decimal 7 aeg. decoder/driver TTL O/P 1100 Up 

7460 Expand dual 2-lnput AXD-OR-IXVERTgatea SOp 18p 

7461 Dual 2-wide 2-lnput AXD-OB-IX VERT gates SOp 18p 
7468 Quad2-ir.put expand AXD-OR-1XVERT gates SOp ISp 
7464 4wide2-inputANDOR-IKVERTgates BOp 18p 

7480 Dual 4-lnput expander* SOp 18p 

7470 Single J-K dip-Bop (gated input-) SOp 87p 

7478 Single J-K flip flop (gated Inputs) .. ..SOp 87p 

7478 Dual J-K flip flop 40p S7p 

7474 Dual D flip flop 40* 87p 

7475 Quadruple bistable latch 44 p 48p 

7478 Dual J-K flip-flops with Preset ami Clear 40p 87p 

7480 Gated Full Adder 76p 78p 

7481 16-bit read/write memory 11 26 £1 10 

7482 2-blt binary Full Adder S7p 80p 

7483 4-blt binary Full Adder HBO £106 

7484 16-blt RAX with gated write Inputs . . Up 80p 
7486 Quadruple 2-lnput Exclusive OR gates . . SSp SOp 

7490 BCD decade counter 75p 70p 

7481 8-blt shltt register UOO Up 

7488 Divide twelve counter 75» 70p 

7498 4-bit binary counter 76p 70p 

7494 Dual entry 4-blt shift register . . 80p 7Sp 

74U 4-blt up-down ahllt register SOp 78p 

74M 5-bit parallel/serial in/out shift register . . 87p SOp 

74100 8-bit bisUble latch 11-50 £140 

74118 Hextuple Set-Reset latchea 11 00 BOp 

74121 Monostable multivibrators SOp 46p 

74141 BCD-Decimal decoder/XIxle driver .. .. UOO Up 

74145 BCD-Decimal decoder (1-4-llne) TTL O/P . U-SO 4140 

74160 16-bit data selector/multiplexer Up 80p 

75151 8-bit data selector/multiplexer 11-00 Up 

741S8 Dual 4-line to 1-llne d»U (elector multiplexer UOO Up 

74164 16-blt decoder/demultiplexer Up SOp 

74156 Dual 2-llne to 4-line decoder/demultiplexer 76p 70p 

74166 Dual 2-line to 4-llne decoder/demultiplexer . . 76p 70p 

74190 Sync decade up-down counter. 1-llne mode . . tt-60 .41-40 

74191 Sj-nc 4-blt up-down counter. 1-llne mode .. 11-80 :!1 85 

74192 Sync decade up-down counter. 2-line mode . . U-76 :!1 65 
74198 8ync 4-bit up-down counter. 2-llne mode .. U 76 :!1 U 
74198 Asynchronous presettable decasle counter U-60 :il 40 
7US7 Asynchronous presettable 4-blt binary counter U-60 :!l-40 
Device i may be mixed to quality for quantity pricing. 

Complete data on the above In booklet 20 page*, Ref. 29. i$tue 2 at lf>p pott paid 
Integrated circuit sockets 14 pin D.I.L. Up; 16 pin D.I.L. SOp. 



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736 



octave, but the RIAA equalising, as it is called, is 
very carefully engineered into the magnetic pickup 
input circuits of hi-fi amplifiers and good quality 
radiograms, etc., so that the response is exactly the 
reciprocal of that shown in Fig. 4. The net result is 
that a 'flat' output from the preamplifier which, of 
course, is the signal requirement of the control 
section and power amplifiers. 

Now, it is the velocity of the imparted modulation 
which follows Fig. 4 curve, and because magnetic 
pickups yield an output proportional to the velocity of 
stylus deflection the output from the pickup applied 
to the equalised preamplifier is thus after the style 
of that in Fig. 4. Hence the reciprocal equalisation 
just referred to. 

A piezo pickup, on the other hand, produces an 
output which is proportional to the amplitude of 
stylus deflection (not velocity). This implies that a 
piezo pickup playing a record cut to the standard 
RIAA response produces an almost 'fiat' output 
without equalisation. 

All piezo cartridges need to be loaded into a very 
high resistance of not less than lMfl and for the best 
results and to secure full advantage of the inbuilt 
equalisation and thus obtain a 'flat' output from a 
disc recorded to the RIAA standard. 

A magnetic cartridge (whose source is inductive), 
however, is commonly designed to work best into 
a load of round 50k«. If it is loaded lower the treble 
tends to fall, while too high a loading can lift the 
treble end of the spectrum and incite undue 'ringing'. 
Conversely, a piezo cartridge (because its source is 
capacitive) exhibits falling bass and rising treble 
when loaded into a resistance significantly below 
lMIi or so. 

The signal yield from a piezo cartridge, even when 
loaded low, is significantly in excess of that from a 
magnetic cartridge when playing modulation of a 
given velocity. This means, therefore, that the piezo 
signal might well have to be attenuated before being 
fed to the magnetic input, to avoid preamplifier 
overload. 




Input response 



Freq "■ 

Output response 



Fig. 5: Circuit of a pre-amplifier incorporating RIAA equalisation. 



The peaks of signal can be clipped when the 
pickup signal veers towards the overload level. 
However, when an 'equalising' pad is included a 
degree of attenuation is automatic, so additional 
attenuation may not be necessary. 

RIAA EQUALISED PREAMPLIFIER 

Shown in Fig. 5 is the circuit of a fairly conven- 
tional RIAA equalised preamplifier. It is common 
to employ two transistors, at least, and in the circuit 
shown, R306/R310/C303/C304 network provides the 
frequency selective network, giving the necessary 
response characteristic inversely to correspond with 
the recording characteristic (Fig. 4). The overall 
effect is that the feedback increases with rising 
frequency and decreases with reducing frequency, 
thereby giving the required treble cut and bass 
boost. 

R303 provides a 'flat' control of gain, and in some 
amplifiers the frequency selective network is 
switched out of circuit when the programme input 
signal requires a 'flat' response, a resistor such as 
R303 then being used to provide the appropriate 
input sensitivity voltage. Stereo equipment embodies 
two such preamplifiers, one for each channel. 

The RC network C306/R311 provides a low-pass 
characteristic, preventing the response from extend- 
ing too far above the audio spectrum. The lOOpF 
capacitor (C308) connected directly across the base/ 
emitter electrodes of the input transistor cuts the 
input response to radio frequencies and thus prevents 
the breakthrough of radio and television interference 
during low-level record replay. 

RADIO/TV BREAKTHROUGH 

Not all amplifiers are equipped with radio and TV 
filtering like this, and since the response of transistor 
stages can embrace the radio and TV spectrums, a 
symptom becoming increasingly common is, in fact, 
radio and TV breakthrough. This mostly happens 
when the equipment is switched to magnetic pickup 
and when it is operated relatively close to a powerful 
radio or TV station. It is encouraged by (i) the high 
sensitivity of the amplifier under this mode of 
operation and (ii) the relative ease at which the 
RIAA preamplifier can be pushed into non-linearity. 

A filter which nearly always clears the trouble is 
given in Fig. 6. The circuit to the base should be 
broken and the 2-2kfl resistor inserted in series, 







Fig. 6: A simple filter to prevent radio and TV signals interfering with 
audio amplifiers. 

while the lOOpF capacitor should be connected right 
across the base /emitter electrodes, as close as 
possible to the input transistor. Both channels should 
be so treated. 

The RIAA preamplifier signals can get into trouble 
so if one channel of a stereo amplifier appears to 
be lacking in bass, with excessive treble output, when 
operating from a magnetic cartridge, then attention 
should be given to the preamplifier department of 
the affected channel. Excessive noise on the magnetic 

737 



input is commonly caused by a defective preamplifier 
transistor or a 'noisy' collector resistor. 

HI-FI SPECS 

It is impossible to detail all the specifications 
relating to hi-fi equipment (further information on 
this score is given in "Tuners and Amplifiers" by 
John Earl, published by Fountain Press), but 
comment on a few of the more important ones would 
not be amiss. 

Power Capacity. This is the maximum power that 
an audio section is capable of delivering with both 
channels running, the maximum being defined either 
to the level of sinewave clipping or to a specified 
value of distortion when the output is loaded by pure 
resistance of appropriate value in place of the 
speaker. The 'standard frequency' is 1kHz, but to 
obtain the power bandwidth the measurement is 
repeated at low and high frequencies. 

Standard Output Power. This is 50mW (17dB/mW). 
However, in some instances values of 500mW 
(27dB/mW) and 5mW (7dB/mW) might be used, 
but the power to which any parameter (such as 
sensitivity) refers should be stated in the specifica- 
tion. 

Input Sensitivity Voltage. This is the input signal 
at 1kHz required to yield the rated output power 
when the volume control is fully advanced, all filters 
'out' and tone controls 'flat'. 

Signal/Noise Ratio. This refers to the voltage due 
to components of hum and noise across the output 
load in terms of dB ratio to the rated output power 
and within the full noise bandwidth of the equipment. 
The volume control is generally fully advanced and 
the selected source input is either short-circuit or 
open-circuit (the former preferred since it avoids the 
pickup of spurious hum and noise components). 

A ratio of 60dB, for example, implies that the 
power of the summed hum and noise in the output 
load is one million times below the full power of the 
amplifier. 

Total Harmonic Distortion (THD). This is 
commonly measured through a distortion factor 
meter, in which a very sharply tuned filter 'notches 
out' the fundamental frequency, leaving only the 
harmonic components. 

Intel-modulation Distortion (IMD). Like THD, IMD 
is a function of amplifier non-linearity. This is 
commonly measured in terms of the amplitude of 
intermodulation components resulting from the 
introduction of two signals to the amplifier, so as to 
produce sum and difference frequencies. 

S/N Ratio (FM). This refers to hum and noise 
relative to a stated modulation level (100% or 30%). 
Measurement is similar to that of S/N ratio of an 
amplifier, and the usable sensitivity of an f.m. tuner 
is commonly given as the input required for a S/N 
ratio of 45dB. 

Owing to the wider passband involved and the 
action of decoding, a stereo receiver has a S/N 
performance below that on mono, particularly at the 
lower signal input levels, which is the reason why 
stereo receivers should always be operated with the 
best possible f.m. aerial system, consistent with the 
location and prevailing signal field on Radio 3. 

END OF SERD2S 



738 



NINE BAND RECEIVER— continued from page 690 



AERIALS 

The telescopi 
it can be bolted 
case, about lin. 
is fitted on the 
aerial. Many tra 
volume with the 
nal aerial will g 
signals. 



: type aerial has a bracket, so that 
directly on the left hand side of the 
from the back. An insulated socket 
side of the case for an external 
nsmissions can be received at ample 
telescopic aerial alone but an exter- 
eatly improve the reception of weak 




DIAL SCALE 

Because each of the nine bands covers a relatively 
small frequency range, the main tuning scale is fitted 
with a card marked to 50. 

The bandswitch has nine positions, and the card 
scale under it has ten frequency markings. The 
bandswitch pointer comes to rest between these 
markings, which thus show the approximate fre- 
quency coverage of that particular range. For 
example, if the pointer rests between 4-6 and 5-0, 
the range is 4-6-5-OMHz, while if it is between 5-0 
and 5-6 the range is 5 0-5-6MHz, covered with the 
normal tuning control. 

The full markings are as follows: 3-6 — 3-8 — 4-3 

4-6— 5 0— 5-6— 3-3— 7 4— 10— 15. This scale is best 
put under the perspex. ■ 



MAXWELL 



by G8DSH 




"—a bi\ of a mismatch somewhere! ' 



Super IC-12 




High fidelity Monolithic Integrated Circuit Amplifier 



Two years ago Sinclair Radionics an- 
nounced the World's first monolithic 
integrated circuit Hi-Fi amplifier, the 
IC.1 0. Now we are delighted to be able to 
introduce its successor, the Super IC.1 2. 
This 22 transistor unit has all the virtues of 
the original IC.10 plus the following 
advantages : 

1. Higher power. 

2. Fewer external components. 

3. Lower quiescent consumption. . 

4. Compatible with Project 60 modules. 

5. Specially designed built-in heat sink. 
No other heat sink needed. 

6. Full output into 3. 4. 5 or 8 ohms. 

7. Works on any voltage from 6 to 28 volts 
without adjustment. 

8. NEW 22 transistor circuit. 



Output power 6 watts RMS continuous 

(12 watts peak). 
Frequency Response 5 Hz to 1 0OKHz ± 

1 dB. 
Total Harmonic Distortion Less than 

1%. (Typical 0.1%) at all output powers 

and all frequencies in the audio band. 
Load Impedance 3 to 1 5 ohms. 
Power Gain 90dB (1 .000.000.000 times) 

after feedback. 
Supply Voltage 6 to 28 volts (Sinclair 

PZ-5 or PZ-6 power supplies ideal). 

Size 22 x 45 x 28 mm including pins and 

heat sink. 
Input Impedance 250 Kohms nominal. 
Quiescent current 8mA at 28 volts. 



With the addition of only a very few external 
resistors and capacitors the Super IC.1 2 
makes a complete high fidelity audio 
amplifier suitable for use with pick-up, F.M. 
tuner etc. Alternatively, for more elaborate 
systems, modules in the Project-60 range 
such as the Stereo 60 and A.F.U. may be 
added. The comprehensive manual supplied 
with each unit gives full circuit and wiring 
diagrams for a large number of applications 
in addition to high fidelity. These include 
car radios, oscillators etc. The very low 
quiescent consumption makes the Super 
IC.1 2 ideal for battery operation. 

Price, inc. FREE 
printed circuit board 
for mounting. 




£2.98 rr 



SINCLAIR GENERAL GUARANTEE 
Should you not be completely satisfield with your 
purchase when you receive it from us, return the 
goods without delay and your money will be 
refunded in full, including cost of return postage, at 
once and without question. Full service facilities are 
available to all Sinclair customers. 



Sinclair Radionics Ltd. London Rd. St. Ives 
Huntingdonshire PE17 4HJ 
Telephone St Ives (048 06) 431 1 

Sinclair- 




739 



Sinclair Project 60 



The World's leading range of high fidelity modules 




New! 



Snclair 

Project 605 
Amplifier 




Project 
605 

The easy way 

to buy and 

build ^H* 

Project 60 Hp^ I 

Project 605 is one pack containing : one PZ5. 
two Z30's. one Stereo 60 and one Masterlink. 
This new module contains all the input sockets 
and output components needed together with all 
necessary leads cut to length and fitted with neat 
little clips to plug straight on to the modules. 
Thus all soldering and hunting for the odd part is 
eliminated. You will be able to add further Project 
60 modules as they become available adapted to 
the Project 605 method of connecting. 

Complete Project 605 pack with f*OQ QC\ 
comprehensive manual, post free £-^C7.C7«J 

All you need for a superb 30 watt high fidelity 
stereo amplifier. 



Sinclair Radionics Limited. London Road. 
St. Ives. Huntingdonshire PE1 7 4HJ. 
Tel: St. Ives (048 06) 4311 

■. i ■ 




Project 60 offers more advantage to the constiuctor and user of high fidelity equipment than 
any other system in the world. 

Performance characteristics are so good they hold their own with any other available system 
irrespective of price or size. 

Project 60 modules are more versatile - using them you can have anything from a simple 
record player or car radio amplifier to a sophisticated and powerful stereo tuner-amplifier. 
Either power amplifier can be used in a wide /ariety of application's as well as high fidelity. 
The Stereo 60 pre-amplifier control unit may also be used with any other power amplifier 
system, as can the AFU filter unit. The stereo FM tuner operates on the unique phase lock 
loop principle to provide the best ever standaids of sensitivity and audio quality. Project 60 
modules are very easily connected together b/ following the 48 page manual supplied free 
with all Project 60 equipment. The modules ere great space severs too and are sold indivi- 
dually boxed in distinctive white and black cartons. With all these wonderful advantages, 
there remains the most attractive of all - price. When you chocse Project 60 you know you 
are going to get the best high fidelity in the world, yet thanks to Sinclair's vast manufacturing 
resources (the largest in Europe) prices are fantastically low and everything you buy is 
covered by the famous Sinclair guarantee of rel ability and satisfaction. 

Typical Project 60 applications 



System 


The Units to use 


together with 


Cost of Units 


Simple battery 
record player 


Z.30 


Crystal P.U.. 12V battery 
volume control 


£4.48 


Mains powered record 
player 


Z.30, PZ.5 


Crystal or ceramic P. U . 
volume control etc. 


£9.45 


20 + 20 W. stereo 
amphfierfor most needs 


2xZ.30s. Stereo 60. 
PZ.5 


Crystal, ceramic or mag. 
P.U., F.M. Tuner, etc. 


£23.90 


20 + 20 W. stereo 
amplifier with high 
performance spkrs. 


2xZ.30s, Stereo 60. 
PZ.6 


High quality ceramic or 
magnetic P.U.. F.M. Tuner. 
Tape Deck. etc. 


£26.90 


40+40W, R.M.S. 
de-luxe stereo amplifier 


2xZ.50s. Stereo 60 
PZ.8, mains trsfrmr 


As above 


£34.88 


Indoor P.A. 


Z.50. PZ.8. mains 
transformer 


Mia. gu'tar, speakers, etc.. 
controls 


£19.43 


FM. Stereo Tuner (£25) & A.F.U. Filter Unit (£5.9(1) 


may be added as required. 





740 



from a simple amplifier to a complete stereo 
tuner amplifier with Project 60 modules 



Z.30 & Z.50 
power amplifiers 




The Z 30 and Z.50 are of advancec design using 
silicon epitaxial planar transistors to achieve un- 
surpassed standards of performance. Total har- 
monic distortion is an incredibly low 0.02% at 
full output and all lower outputs Whether you 
use Z 30 or Z.50 amplifiers in your Project 60 
system will depend on personal preference, but 
they are the same size and may be used with 
other units in the Project 60 range equally well. 
SPECIFICATIONS (Z.bO units are inter- 
changeable with Z.30s in all applications). 
Power Outputs 

Z.30 15 watts R.M.S. into 8 ohms using 35 volts: 
20 watts R.M.S. into 3 ohms using 30 volts. 
Z.50 40 watts R.M.S. into 3 ohms using 40 volts: 
30 watis R.M.S. into 8 ohms using 50 volts. 
Frequency response : 30 to 300.000Hz ± 1 dB. 
Distortion : 0.02% into 8 ohms. 
Signal to noise ratio: belter than 70dB unweighted. 
Input sensitivity: 250mV into 100 Kohms. 
For speakers from 3 to 1 5 ohms impedance. 
Size: 14x80x57 mm. 

Z.30 

Built, tested and guaranteed with circuits and instruc- 
tionsmanual. £4.48 

Z.50 

Built, tested and guaranteed with circuits and instruc- 
tions manual. £5.48 



Power 
Supply 
Units 

Designed special for use 
with the Project 60 system 
of your choice. Use PZ 5 
for normal Z.30 assemblies 
and PZ.6 where a stabilised 
supply is essential. 

PZ.5 30 volts unstabiHsed£4.99 
PZ.6 35 volts stabilised £7 .$9 
PZ.8 45 volts stabilised 
(less mains transformer) £7.98 
PZ.8 mains transformer £5.98 




The Sinclair Guarantee 

If within 3 months of purchasing Project 60 modules 
directly from as, you are dissatisfied with them, we will 
refund your money at once. Each module is guaranteed 
to work perfectly and should any defect arise in normal 
use we will service it at once and without any cost to 
you whatsoever provided that it is returned to us 
within 2 years of the purchase date. There will be a 
small charge for service thereafter. No charge for 
postage by surface mail. Air- mail charged at cost. 



Project 60 Stereo F.M. Tuner 

First in the 

• world to use the 

phase lock loop principle 

The phase lock loop principle was used for receiving signals from space craft because of 
its vastly improved signal to noise ratio. Now. Sinclair have applied the principle to an F.M. 
tuner with fantastically good results. Other original features include vancap diode tuning. 
printed circuit coils, an I C. in the specially designed stereo decoder and squelch circuit for 
silent tuning between stations. Good reception is possible in difficult areas, and often a 
few inches of wire are enough for an aerial. In terms of a high fidelity this tuner has a lower 
level of distortion than any other tuner we know. Stereo broadcasts are received automatic- 
ally as the tuning control is rotated, a panel indicator lighting up as the stereo signal is 
tuned in This tuner can also be used to advantage with any other high fidelity system. 
SPECIFICATIONS— Number of transistors: 1 6 plus 20 in I C. Tuning range: 87.5 to 108 MHz 
Capture ratio: 1.5dB. Sensitivity: 2u,V for 30dB quieting: 7nV lor lock-in over full deviation. 
Squelch level: 20uV. A.F.C. range: ±200 KHz. Signal to noise ratio: >65dB. Audio fre- 
quency response : 10 Hz- 15 KHz ( ildB). Total harmonic distortion: 0.15% for 30% modula- 
tion. Stereo decoder operating level: 2\xM. Cross talk: 40dB. Output voltage: 2 x 150mV 
R.M.S. Operating voltage: 25- 30 VDC. Indicators: Power on/tuning/stereo. 
Size: 93x40x207 mm. -P9R 

Built and tested. Post free. fc*W 



Stereo 60 Pre-amp/control unit 



•##• 



• • • # 



KB* 



Designed for Project 60 range but suitable for use with any high quality power amplifier. 
Again silicon epitaxial planar transistors are used throughout, achieving a really high 
signal-to-noise ratio and excellent tracking between channels. Input selection is by 
means of push buttons and accurate equalisation is provided for all the usual inputs. 
SPECIFICATIONS— Input sensitivities: Radio -up to 3mV. Mag. p.u. 3mV: correct to R.I.A.A 
curve ±1dB:20 to 25.000 Hz. .Ceramic p.u. -up to 3mV: AUx-up to 3mV. Output: 250mV. 
Signal to noise ratio: better than 70dB. Channel matching: within IdB. Tone 
controls: TREBLE + 15 to— 15dB at 10 KHz: BASS I 15 to — 15dB at 100Hz. 
Front panel : brushed aluminium with black knobs and controls. Size : 66 x 40 x 207mm. fQ QQ 
Built rested and guaranteed. i-U.I/O 



A.F.U. High & Low Pass Filter Unit 

For use between Stereo 60 unit and two Z.30s or Z.50s. 
and is easily mounted. It is unique in that the cut-off 
frequencies are continuously variable, and as attenuation 
in the rejected band is rapid (1 2dB/octave). there is less 
loss of the wanted signal than has previously been possible. Amplitude and phase dis- 
tortion are negligible. The A.F.U. is suitable for use with any other amplifier system. Two 
filter stages -rumble (high pass) and scratch (low pass). Supply voltage- 15 to 35V. 
Current - 3mA, H.F. cut-off (-3dB) variable from 28KHz to 5KHz. LF. cut-off (-3dB) 
variable from 25Hz to 1 00Hz. Distortion at 1 KHz (35V. supply ( 0.02% at rated pg- qq 
output. Size: 66 x 40 x 90 mm. Built tested and guaranteed. tO.JJO 



To: SINCLAIR RADIONICS LTD LONDON ROAD ST. IVES HUNTINGDONSHIRE PE17 4HJ 



Please send 


Name 
Address 






I enclose cash/cheque/money order. 


PW 12 



741 



Sinclair Q16/Micromatic 



Q16 High fidelity loudspeaker 

The 01 6 employs the well proven acoustic 
principles specially developed by Sinclair 
in which a special driver assembly is 
meticulously matched to the characteristics 
of the uniquely designed cabinet. In re- 
viewing this exclusive Sinclair design, 
technical journals have justly compared 
the Q16 with much more expensive loud- 
speakers. Its shape enables the Q16 to be 
positioned and matched to its environment 
to much better effect than is the case with 
conventionally styled enclosures. A solid 
teak surround with a special all-over 
cellular foam front is used as much for 
appearance as its ability to pass all audio 
frequencies without loss. 

This elegantly designed shelf mounting 
speaker brings genuine high fidelity within 
reach of every music lover. 



Specifications: 

Construction: Special sealed seamless 

sound or pressure chamber with internal 

baffle. 

Loading : up to 1 4 watts RMS. 

Input Impedance: 8 ohms. 

Frequency response : From 60 to 1 6.000 

Hz. confirmed by independently plotted B 

and K curve. 

Driver unit: Special high compliance unit 

having massive ceramic magnet of 11,000 

gauss, aluminium speech coil and special 

cone suspension for excellent transient 

response. 

Size and styling : 9 J in. square on face x 

4f in. deep with neat pedestal base. Black 

all over cellular foam front with natural solid 

teak surround. 

Price £8.98. 




Britain's smallest radio 

Considerably smaller than an ordinary box 
of matches, this is a multi-stage AM 
receiver brilliantly designed to provide 
remarkable standards of selectivity, power 
and quality for its size. Powerful AGC 
counteracts fading from distant stations: 
bandspread at higher frequencies makes 
reception of Radio 1 easy. The plug-in 
magnetic earpiece provided, matches the 
Micromatic's output to give wonderful 
standards of reproduction. Everything 
including the special ferrite rod aerial and 
batteries is contained -within the minute 
attractively designed case. Whether you 
build a Micromatic kit or buy this amazing 
receiver ready built and tested, you will find 
it as easy to take with you as your wrist 
watch, and dependable under the severest 
listening conditions. 



Specifications: 

Size: 36x33x13 mm (1.8x1.3x0.5 in.) 
Weight: including batteries, , 28.4 gm 
(1 oz.) 

Case: Black plastic with anodised 
aluminium front panel and spun aluminium 
dial. 

Tuning: medium wave band with band- 
spread at higher frequencies (550 to 
1.600 KHz). 

Earpiece: Magnetic type. 
On/off switching: By inserting and 
withdrawing earpiece plug. 
Kit in pack with earpiece, case, instructions 
and solder £2.48. 

Ready built, tested and guaranteed, with 
earpiece £2.98. 

Two Ma/lory Mercury batteries type 
RM675 required from radio shops, 
chemists, etc. 




To: SINCLAIR RADIONICS LTD LONDON ROAD ST. IVES HUNTINGDONSHIRE PE17 4HJ 

Rleasesend 



for which I enclose cash/cheque/money order 



Name 



Address 



PW1271 



742 



Sinclair Radionics Ltd.. London Rd, St. Ives 
Huntingdonshire PE17 4HJ. 
Telephone St. Ives (048 06) 431 1 



■ I ■ 

iinczlBir— 




LIGHT DIMMER 

The unit corned complete with 
MK Ivory Front Plate and 
Control Knob, when used in 
place of Light Switch It will 
control your room lighting from 
off to full brightness. 
Power — up to 300 watts inter- 
ference suppressed. 

£2-75 r. * p. 8 P 



*9 



SOLID STATE BLOCK MODULES 

Phono pre-amp E1311 Input 

100k: gain 28dB max out 

3 volt: max input 60mV. 

Tape pre-amp as above E 1 313. 

Power aniD El 314 input 1.000 

ohms gain 20dB SOOmW. 

Organ tone oec EI31S tone 

freq. 200- Ik. Hz output 80m W. All above modules 9 

volt. Dual flasher E1318 flash time 1-4 sees power 6 

volt. Lamp 6v ISOmA. All at 11.86 P. * P. lOp 



D.P.D.T. SLID! 
SWITCH 



f,p 



SIZE 

11 ins long A wide 

•3p 3p Postage 



Transformer 
Scoop 



Primary 220, 260 v. fused. 
Secondary 220 v. at 80mA, 
6-Sv. at 1 amp. 
Overall stae 2»- x 2- x 2|' 
high. £>„ each. 

OJ P P. * P. 16p. 



MME 



COMPONENT CENTRE 

8x6 Printed circuit board 10f each 

BvlOO Type rectifier 800 Plv 750 mA Up „ 

4 Pin transistor holders Sp „ 

21 8 ohm speaker 33d ,, 

U'J Battery holders 6p „ 

10OHM W/W Pots Up „ 

OC81 Beat clips (double! Sp 

Tape rev counters ttp 

1.500mF 150v DC 4* x V dla approx 40p 

Flex connecto r 2amp approx non-reversible 

Ideal for loudspeaker connections 8p „ 

'-■; 80 ohm Speaker 38p ., 

Please include Post A Packing 
fb*t4 S.A . E. tor "turn of pott fflaff of your rUHronlr projrrt. 



He 40 MAYES RD LONDON N22- 888 3206 

13 SOUTH MALL EDMONTON GREEN LONDON N9 803 1685 




CHR0M0SONIC SOUND 
OPERATED LIGHT 

DISPLAY 

This compact unit (size 81* X BJ' X 
S' high) 1b connected directly across the 
speaker ontput of an amplifier, it will than con- 
vert audio Bignals into a spectacular three colour 
light display (600 watts light out- 
put each colour). Send S.A.E. for / I ft.Cfi 
further details or call in at any *» , *» * v 
branch for demonstration. P. & P. 38p 




Open and short circuit proof 
Sensitivity lOmV for full output 
Frequency Response 10-25,000Hz 
Safe with all loudspeaker systems 
4 to 16 ohms 

Silicon transistors used throughout 
F.E.T. Front end 

Send S.A.E. for further details. 



Sdl.fafl U purchased 
"*' W with llirht nn 



ith light unit above 
1 Insurance £1 00. 



£40-00 



GUARANTEED 12 MONTHS 



DWELL TIME UNIT 

These small units contain the 

following components: 700 ohm 

DPDT relay with base. ljiF 

260v. paper, 0-81/iF 400v. paper, 

50utf 36 v. electrolytic, 3 diodes 

OC200 transistor, a 2N2926 

type transistor unmarked, a 

skeleton pre-set pot, 4 pin din 

plug A akt., 4 foot of 4 core 

screen. All housed in a small neat metal box. Can 

be made into many timing devices. f4'l[% P a P 8p 




TOP QUALITY — LOW COST 




AMATEUR RADIO EQUIPMENT 



(SELIjZaXDG 




MULTIBAND-6 TRF SHORT WAVE RECEIVER I 
KIT | 

This new all transistor T.R.F. Receiver tunes 550 Khz-30 Mhz (540-10 I 

metres) complete coverage, no gaps. Trawlers. Ship to Shore telephone. ' 

Six Amateur Bands. 160-10 metres. International Broadcast. Australia, I 

Far East. Russia, USA. etc. etc., using miniature plug in coils. 

Hi-Gain FET Regen. Det. Pre-Amp A.F. A.F. Module giving full loud i 

speaker output to any external 2 3 ohm speaker. 

Two separate Tuning Dials. Calibrated Mhz and Degrees. Electrical 

Bandspread on all bands. 

Handsome styling with Black Perspex Panel, Steel Cabinet in Charcoal 

finish with Chrome Trim. 

This is a quality CODAR-KIT with full 12 months guarantee. No 

technical knowledge required, printed circuit construction. Instruction | 

Manual with pictorial drawings backed by friendly Help-U After Sales 

Service if you have any queries. 

Complete Kit (even to the resin-cored solder) 

with 3 Coils. £11-50 Carriage 50p. 
Available NOW. NEW AT5 MK 2. 12 WATT. Transmitter 160-80 | 
metres. Also NEW PR40 FET Pre-Selector. Stamp brings illustrated . 
leaflets. 




CR 70A 
COMMUNICATION RECEIVER 



The CODAR CR 70A is an outstanding general coverage communication 
receiver, ideal for the keen S.W.L. 

't tunes from 540 metres medium through to 10 metres with no gaps. 
Covers shipping, coastguard and distress frequencies, all six amateur 
bands 160-10 metres, international broadcast, Met. stations etc. etc. 
giving world-wide reception. Exclusive features include Air-spaced 
CODAR-COIL Hi-"Q" Aerial input. Illuminated "S" Meter and Slide 
Rule Scale, Two Speed vernier tuning. Separate B.F.O. for CW/SSB 
signals, 5 valves inc. cwo twin triodes giving 7 valve line-up, separate 
output for Tape recorder. 

Ready to plug in to 200/240 volts A.C. it only needs your aerial and a 
2/3 ohm loudspeaker to bring the world to your finger tips. 12 
months full guarantee. 

Complete ready built £24-50, Carriage 50p. 
Ask the chap who's got one, there's lots of them ! 



ON THE DESIGN STAFF— 
G3SZM G3IRE G8BBI 



CODAR RADIO COMPANY 

Unit 1, Meadow Road Industrial Estate, East Worthing, Sussex. 



743 



The lamest selection 



NEW LOW PRICE TESTED S.C.R.'s 



PIV 1A 



I A 



74 



TO-5 10-66 TO-i 

*P *? Sp 

SO MS 0-24 0-47 

100 MS MS 0-58 

200 MS 0-37 0-57 

400 MS 0-47 0-67 

600 MS M7 0-77 

BOO MS 0-70 0-00 



*P 

0-60 
068 
Ml 
0-75 
0-97 
120 



TO-48 TO-48 



0-58 
0-68 
0-76 

0»J 
125 
1-60 



1-16 
1-40 
1-60 
1-76 

4-00 



SIL. RECTS 

PIV 300mA 750mA 1A 

*P *P Sp 

0-04 0-05 0-05 

0-04 0-06' 0-06 

MS MO 0-08 

400 0-08 0-13 ' 0-07 

600 047 0-16 0-10 

MO 0-17 0-13 

Ml 0-25 0-16 

— 0-SS — 



60 
100 
200 



800 
1000 
1200 



TESTED 

1-5A 3 A 

<P Sp 

0-07 0-14 

0-18 0-16 

0-14 0-20 

0-20 0-27 

0-23 0-34 

0-26 0-87 

0-30 0-46 

0-33 0-57 



10A 30 A 

Sp So 

0-21 0-47 

0-28 0-75 

0-24 1-00 

0-37 1-25 

0-46 1-85 

0-56 2-00 

0-83 2-50 

0-76 - 



TEIACS 

VBOM 2 A 6A 10A 

TO-1 TO-66 TO-88 

Sp Sp flp 

100 0-60 0-83 1-00 

200 0-70 0-90 1-25 

400 0-M 100 1-60 



LUCAS SILICON 
RECTIFIERS 

sn aa», -ton p.i.i. *hu1 

type. £1 lOp each. 



DIAC8 
FOR U8E WITH 
TRIAC8 
BR1O0 . . . . 87p each 



2A POTTED BRIDOE RECTIFIERS 200V 60p 



UBUUSCT10B 
UT48. Eqvt. 2N2646. 
Eo.vt. TI843. BEN3O00 
S7p each. 25-99 S5p 
100 UP 20p. 



m SILICOH PLAJAR 
BC107/8/9. lOp each; 
50-99, 9p; 100 up, 
8p each; 1,000 ofl, 
7p each. Fully -tested 
and coded TO-18 case. 



FREE 

One 60p P»k ol you 

owe choice tree with 
orten valued S4 or our. 



AF239 PNP GERM, 
8IEMEN8 VHF TRAN- 
SISTORS. RF MIXER 
ft OSC. UP TO 900 
MHZ. USE AS RE- 
PLACEMENT FOR 
AF139-AF186 4 100's 
OF OTHER USES IN 
VHF. OUR SPECIAL 
LOW PRICE :— 1-24 37p 
each, 25-99 S4p each 
100 + SOp each. 



FETS 

2N 3819 86p 

2N 3820 93p 

MPF105 40p 



CADMIUM CELLS 

ORP12 43p 
ORP60, ORP61 40p each 



PHOTO TRANS. 

OCP71 Type. 43p 



SIL. G.P. DIODES Sp 
SOOmW 30 . . 0-50 

40PIV (Min.) 100 . . 1-60 
Sub-Mln. 500 . . S-00 

Full Tested 1,000 . . 8-00 
Ideal for Organ Builders. 



D1SD1 Silicon Unilateral 

•witch SOp each. 
A Silicon Planar, mono- 
lithic Integrated circuit 
having thyristor elec- 
trical characteristics, but 
with an anode gate and a 
built-in "Zener" diode 
between gate and 
cathode. Full data and 
application circuit* avail- 
able on request. 



AD 161 m 
AD 1 62 p SP 

MATCHED COMPLE- 
MENTARY FAIRS 
OF GERM. POWER 
TRANSI8TOR8. 
For mains driven out- 
put stage of Amplifiers 
and Radio receivers. 
OUR LOWEST PRICE 
OF 63p PER PAIR 



PNWfi li5 WATT SIL. 
OUR PRICE SSp EACH 



FULL RASOE OF 
ZEjTER DIODES 
VOLTAOE RAJOE 

2-33V. 400mV (DO-7 
Case) 13p ea. 1|W (Top- 
Hat) 18p ea. I0W (80-10 
Stud) SSp ea. All fully 
tested 5% tol. and 
marked. State voltage 
required. 



BBAHD »EW TEXAS 
GERM. TRANSISTORS 
Coded and Guaranteed 
Pak No. EQVT 

8 2G371A OC71 
8 2G374 OC75 
8 203744A OC81D 
T4 8 2G381A OC81 
T5 8 2G382T OC82 
T6 8 2G344A OC44 
T7 8 2G345A OC45 
T8 8 2G378 OC78 
T9 8 2G399A 2N1302 
T10 8 2G417 AF117 
All SOp each pak 



W 



2H2060 HPH SIL. DUAL 
TRAMS. CODE D1B99 
TEXAS. Our price 25p 
each. 



120 VCB IIXIE DEXTER 
TRANSISTOR. 81m. 

B8X21 ft C407, 2N1893 
FUtLY TE8TED AND 
CODED ND120. 1-24 
17p each. TO-5 N.P.N. 
25 up 16s each. 



811. trans, suitable for 
P.E. Organ. Metal TO-18 
Eqvt. ZTX300 6p each. 
Any Qty. 



EX-BaUIPstBltT 
MULLARD 
AF1 17 transistors. Large 
can 4 lead* type. Leads 
cut short but still usable, 
real value at 15 for 60p. 



KING OF THE PANS 

SUPER PAKS 



Unequalled Value and Quality 

NEW BI-PAK UNTESTED 
SEMICONDUCTORS 



Satisfaction GUARANTEED in Every Pak. or money back. 

Pak No. 

T_'l 120 Glass Mib-min. general purpose germanium diodes 



U2 60 Mixed germanium transistors AF/RF 

US 76 Germanium gold bonded diodes aim. OA5, OA47 
U4 40 OennaiiiumlransUtors like OC8i7aC128 



80 200mA sub-mln. Bit, diodes . 



Ufl 

U8 30 SMcorTplanar transistors NPNalm. B8Y93A, 2N706 



111 Silicon rectlllera Top-Hal 750mA up lo 1,000V . . . 

"SO 811. planar diodes 250mA, OA/200/202 

20 Mixed vniti I watt Zener diodes 

30 PNP Hilicuu planar transistors TO-5 slm. 2Nil32~ 
30 PNP-NPN all. transistors OC200 k 281047.777; 



10 3-Amp silicon rectifiers stud Cype up to 1000 PIV 

SO OcrrnMhnnPNF AF trarnlsiorsTO-5 ¥ke ACY 17^22~ 



111 
U13 

U14 150 Mixed silicon and germanium diodes 

UK. -J.- NPN SiliconTuuiar transistors Tb-5~slm.~iiN697 

Pie 

U17 
U18 

U19 25 Silicon NPN transistors like BC108 

U20 ~l51 V Amp'iilicon rectlllera Top-Hat up to 7.000 PIV 

Uai 30 A.F. gen nanlnm alloy transisto rs 2O300 aeries * O 

D 33 SO Madt's like MAT aeries PNP tranalaton 

U24 20 Germanium 1-Amp rectifiers GJM up to 300 PIV . 

U23 25~300Hc/» NPN silicon transistors 2N708, B8Y27 . . 




8 6- Amp silicon rectifiers BYZ13 type up to 800 PIV , 
33 Silicon NFlTtra 



U26 

P88 

U29 
U31~ 
U33 
U33 



30 Fast switching silicon diodes like IN914 micrc-min 



Experimenters' assortment of integrated circuits, untested. 

Gates, flip-flops, registers, etc-. 8 assorted pieces 

10 1-AmpSCR'* TO-5 can up to SMPIV CR81/25-6O0 



20 811. Planar NPN trans, low noise amp 2N8707 

25 Zener diodes 400mW D07 case mixed volts, 3-18 

15 Plastic case 1 amp silicon rectifiers IN4000 series 



U34 30 811. PNP alloy tram. TO-5 BCY28. 28302/4 



U35 25 811. planar trans. PNP TO-18 2N2906 

U36 25 Sll Tplanar MPM tram. TO-5 BFY50/51/52 . ■ .777 ! . . 

P37 ~ 30 BliTiEoy trans. 8Q-2 PNP. OC200 28322 

U38 20 Fast switching all. trans. NPN. 400Mc/s 2N301 1 . 7 . 



U39- 30 RF germ. PNP trans. 2N1303/5 TO-6 0-50 

U40 10~Duai Iran... '1 lead TO -5 IHM O O .177777777 .7 . .7 0^50 

D < 1 » RFgcrm . tr ans. TO -1 OC45 NKT7 2 ■ ■ ■ ■ ■■■■■ M0 

U42 10 VHF germ. PNP trans. TO-1 NKT667 AF117 7 0*0 



Code Nos. mentioned above are given as a guide to the type >f device In 
the Pak. The devices themselves are normally unmarked. 



NEW QUALITY TESTED PAKS 



Mm 
fp 

20 Red spot trans. PNP AF MO 

16 White spot R.F. trans. PNP 0-60 

4 OC77 type trans 0-50 

6 Matched trans. OC44/45,'8].'81D . . 0-60 

4 OC75 transistors 0-M 

4 OC72 transistors 0-50 

4 AC128 trans. PNP high gain 0-60 

4 AC128 trans. PNP M0 

7 OC81 type tran 0-M 

7 OC7P type trans 0-M 

3 AC127/128 comp. pairs PNP/S PN . . 0-M 

3 AF116 type trans. 0-M 

3 AF117 type trans 0-M 

3 OC171 H.F. type trans 0-M 

5 2N292H ail. epoxy Uane 0-50 

3 GET8S0 low noise germ, trans. . . . 0-M 

3 NPN 1 ST141 & 2 8T140 0-M 

4 Madt's 2 MAT 100 * 3 MAT 120 . . 0-M 

3 Madfe 2 MAT 101 4 1 MAT 121 . . MO 

4 OC44 genu, trans. A.F 0-M 

3 AC127 NPN germ, trans 0-M 

20 NKT trans. A.F. R.F. coded 0-M 

10 OA202 sil. diodes sub-min 0-M 

8 OAS1 diodes 0-M 

« IN914 sil. diodes 70PIV 75mA 0-M 

8 OA95 germ, diodes sub-min. 1N69 . 0-M 

2 10A 800 PIV ail. reels. I845R 0-M 

2 8H. power reels. BYZ13 0-60 

4 811. trans. 2 X 2N696, 1 X 2N697. 

1 X 2N898 0-M 

7 Sil. switch trans. 2N706 NPN 0-M 

6 Sil. switch trans. 2N708 NPN M0 

3 PNP sil. trans. 8 X 2N113I. 

1 X 2N1132 0-M 

3 Sil. NPN trans. 2N1711 0-M 

7 Sil. NPN trans. 2N2369. 500MHZ.. 0-M 
3 Sil. PNP TO-5 2 X 2N2904 & 

1 x 2905 0-50 

7 2N3646 TO-18 plastic 300MH2 

NPN 0M 

3 2N3053 NPN all. trans 0-M 

7 PNP trans. 4X2N3703, 3X2N3702 0-50 

7NPN trans. 4X2N3704. 3X2N3705 0-M 

7 NPN amp. 4X2N3707. 3X3N3708. 0-60 

3 Plastic NPN TO-18 2N3904 0-M 

6 NPN trans. 2N5172...^ 0-M 

7 BC107 NPN trans. ...C 0-M 

7 NPN trans. 4XBC10S. 3X11CI09.. 0-80 

3 BC113 NPN TO-18 trans 0-M 

3 BC1IS NPN TO-5 trans 040 

fiNPNhighgain3xBC167.3xBC168 0-M 

4 BCY70 NPN trans. TO-18 0-50 

4 NPN trans. 2XBFY51. 2XBFY52 0-M 

7 B8Y28 NPN switch TO-18 0-M 

7 BSY95A NPN trans. 300MH2 0-60 

8 BY 100 type sil. rect 1-00 

25 Sil. ft germ, trans, mixed all 

marked new 1-50 



Pak Description 



PRINTED CIRCUITS— EX-COMPUTER 

Packed with semiconductors and components, 
10 boards give a guaranteed 30 trans and 30 diodes. 
Our price 10 boards, 50p. Plus lOp P. ft P. 
100 Boards S3, P. & P. 30p. 



\ GENERAL PURPOSE GERM. PNP 
POWER TRANSISTORS 

Coded GP100. BRAND NEW TO-3 CASE. POSS. 
REPLACEMENTS FOR:— OC25-28-29-30-35-36. NKT 
401-403-404-405-406-430-451-452-453. TI3027-S028, 
2N250A. 2N458A-457A-458A. 2N611 A * B. 2O220- 
222. ETC. 
SPECIFICATION 

VCBO 80V VCEO 50V IC 10A PT. 30 WATTS Hfe 
30-170. 

PRICE 1-24 25-99 100 up 

48p each 40p each SSp each 

GENERAL PURPOSE SILICON NPN 
POWER TRANSISTORS 

Coded GP300. BRAND NEW TO-3 CASE. POSSIBLE 
REPLACEMENT FOR;-2N3056, BDY20, BDYH. 
SPECIFICATION 

VCBO 100V, VCEO «0V. IC 15AMP8. PT. 1 15 WATTS. 
Hfe 20-100. FTI MHZ 

PRICE 1-24 25-99 100 up 

55p each 50p each 47p each 



JUMBO 

COMPONENT 

PAKS 

MIXED 
ELECTRONIC 
COMPONENTS 

Exceptionally 
food value 
(no rubbish) 

Resistors, capacitors, 
pots, electrolytic* and 
coils plus many other 
useful items. Approxi- 
mately 31b- in weight. 
Price Incl. P. 4 P 

£1 -SO only 

Plui our ialii faction or 
montjf back guarantee. 



OEMERAL PURPOSE MPsT STUCOX SWITC'HUO TRARS. TO-18 SIM. TO 2K706-8, 
BSY27/38/96A. All usable devices no open or short circuits. AL80 AVAILABLE in 
PNP Sim. to 2N2906, BCY70. When ordering please state preference NPN or PNP. 
Sp 100 For 1 76 

20 For 0-60 600 For 7-50 

50 For 1-00 1000 For 1800 



NEW EDITION 1971 

TRANSISTOR EQUIV ALEUTS 

BOOK. A complete cross reference 
and equivalents book for European, 
American and Japanese Transis- 
tors. Exclusive to BI-PAK 90p 
each. 



GERM 


. POWER TRANS. 




Price 




Price 


Type 


each 


Type 


each 


OC20 


SOp 


OC29 


SOp 


OC22 


SOp 


OC35 


SSp 


OC23 


Ma 


OC36 


40p 


OC25 


esp 


AD140 


40p 


OC26 


Urn 


ADI42 


«*P 


OC28 


40p 


AD149 


SSp 



OUR STOCKS of individual devices 
are now too numerous to mention in 
this Advertisement. Send 8.A.E. 
for our listing of over 1,000 
Semiconductor!. All available Ex- 
Stock at very competitive prices. 



SILICOI PHOTO TRAR- 
SI8TOR. TO-18 Lena end. 
NPN Sun. t.iBPx25and P21. 
BRAND NEW. Full data 
available. Fully guaranteed. 

Qty. 1-24 25-99 100 up 

Price each 45p 40p tSp 



RTL MICROLOGIC CDlCUITS 

Price each 
Epoxy TO-5 case 1-2 1 26-99 100 up 
uL600 Buffer 85) SSp S7a 

UL914 Dual 21/p 

fate 86 > SSp S7p 

UL923 J-K flip-flop SO> «7p 46p 
DaU and Circuits Booklet for I.Cs 
Prke7p. 



Dual-in-Line Low Profile Sockets 

14 and 18 Lead Sockets for use with 

Dual-ln-Line Integrated Circuit* 

Price each 
Order lo. 1-24 25-99 100 up 

TSO 14 pin type SOp 27p SSp 
TSO 16 pin type 35p SSp 30p 



- the lowest prices ! 



74 series T.T.L. I.C's 

DOWN AGAIN IN PRICE 




Check our 74 Series List before you huy any I.t"«. Our print ire 

tko lowest »OMikle. All devices ex-stock. I | 

Full spec guaranteed. 

BI-rAK Price an* jly. prices 

OrsVrKo. Similar Tjpes lo:- Description 1-84 25-99 100 up 

*■ tp ip 

BPOO-7400 Quad 2-input NASD gate 015 0-14 0-12 
BP01 — 7401 Quad •.'■input pos. NAM!) gate 

(with open collector output) . . 0-14 0-14 012 

BP02 - 740-.' Quad 2-lnput pos. NOR gate. . 0-15 0-14 0-12 
BP03 — 7403 Quad '-'-input pos. NAND galea 

(with open collector output) . . 0-16 0-14 0-12 

BP04 - 7404 Hex Inverters 015 - 0-14 012 

BP0S - 7403 Hex Inverter (with "iien-collcctor 

output) 015 14 0-18 

BP10 — 7410 Triple 3-input pos. NAND galea . . 0-15 0-14 012 

BP13 - 7413 Dual 4-input Schmitt trigger . . 0-29 0-26 0-24 

BP20 « 7420 Dual 4-input pun. NAND galea 0-16 0-14 012 

BP30 - 7430 K-input pew. NAND gates 0-15 0-14 0-12 

BP40 - 7440 Dual 4-input poo. NAND buffer* . 0-16 014 012 

BP41-7441 BCD lo decimal nixie driver 0-07 0-M 0-68 
BP42 — 7442 BCD to decimal decoder (4-10 line". 

1 of 10) 047 0-64 0-68 

BP48 •» 7446 BCD-to-seven-segmcnl decoder/driver 200 1-76 1-80 
BP47 — 7447 nC'D-.ieven-negment decoder/drivers 

( 15 V outputs) 0-07 0-M 0-88 

BP4S - 7448 BCD-to-sevcnsegnieiit decoder/driver 0-97 0-»4 0-88 
BP30 — 7450 expandable dual '-'-input ariil-or- 

invert 0-16 0-14 0-12 

BP51 — 7451 Dual 2-w iile '.'-input and-or-lnvrrt 

gate- 0-18 0-14 0-12 

BP5S — 7453 Quad 2-inpul expandable and-ur- 

invert 0-16 0-14 0-12 

BP54 - 7404 4-wide 2-input and-or-invert gate* . 0-16 014 0-12 

BP60 - 7460 Dual 4-inpul expander 0-16 0-14 0-12 

BP70 » 7470 Single-phase J-K flip-Hup 0-28 0-28 0-24 

HP7'.' - 747'.' Muter slave J-K Hip-flop . 0-2S 028 0-24 

BP73 - 7478 Dual Master slave J-K tlip-fl<ip . . 0-87 OS6 0-82 

BP74 - 7474 Dual D type flip-flop 0-87 0-86 0-82 

BP75 - 7473 Quad latcb 047 0-46 0-42 

BP7S — 747K Dual J-K with pie -art ami clear . . 0-48 O40 0-88 

BP80 - 7480 dated lull adders 047 0-64 0-68 

BP61 - 7481 IB-bit read/write memory 0-07 0-04 0-88 

BP82 - 7482 2-bit binary lull adder. 0-97 94 0-88 

BP83 - 7483 Quad lull adder 1-10 1 05 0-96 

BP86 - 7486 Quail 2-input exclusive NOR galea 0-82 0-80 0-28 

BP90 - 7490 BCD decade counter 047 0-84 0-58 

BP91-7491 *-bit shift registers 0-87 084 0-78 

BP92 •- 7492 Divlilc-by-lwelve counter- . . 047 0-84 0-58 

BF93 - 7493 4-bit binary counters 047 0-84 0-66 

BP94-7494 Dual entry 4-blt shift regiater 0-77 74 048 

BP95 — 749.". 4-bit up-down -hilt register . . 0-77 74 088 
RP96 - 7496 ..-bit parallel in parallel out ahilt- 

register 0-77 074 0-68 

BP100 - 74100 H-blt bistable latches 1-76 166 1-66 
HP104 - 74104 Single J-K flip-flop equivalent !KK>» 

series 0-97 994 0-88 

BP100 - 74103 Mingle J-K flip flop equivalent 9001 

aeries • 0-97 94 0-88 

BP107 - 74107 Dual Master slave fllptlopa .. 0-40 88 0-88 

BP110- 74110 Hates master-slave flip-flops 0-66 0-53 0-60 

BP111 - 74111 Dual data lock-out flip-flop . 1-26 1-16 1-00 

BP118 - 74118 Hex set-reset latches 1-00 05 0-90 

BP1 19 — 74119 Hex set-reset latches. 24-pin 146 1-26 1-10 

BP121 - 74121 Monostable multivibrators .. 087 044 0-58 

BP141 - 74141 BCD-to-declmal decoder/driver . . 0-87 044 0-68 

BP146 - 74143 BCD-to-decinuU decoder/driver Of 1-60 1-40 1-80 

BP150 - 74130 lfi-blt data selector 1-80 1-70 140 

BP101 - 74151 8-bltdaU selectors (with strobe) 1-00 0-95 0-90 

BP153 - 74153 Dual 4-line-to-l-line data 1-20 110 0-96 

BP1 34 - 74134 4- to 16-ltno decoder 1-80 1-70 140 

BP15S — 74153 Dual 2- to 4-line decoder 1-40 1-80 1-20 

BPlufl - 74156 Dual 2- to 4-llne decoder O/C . . 1-40 140 140 

HP inn - 74160 Svnr. decade counter 1-80 1-70 140 

BP161 - 74161 8ync. 4-blt binary counter . . 1-80 1-70 140 

BP190 - 74190 Bync. up-down BCD counter 3-50 346 3-00 
BP101 — 74191 Sync, binary up-down counter ("ingle 

clockline) 3-60 3 25 3 00 

BP192 - 74192 Sync, up-down decade counter 2-10 1-96 1-76 
BP193 — 74193 Sync, binary tip-down counter (tow 

i lock lines) 2-10 196 1-76 

BP196 - 74196 Pre-seUble 50MHz decade counter . 140 1-70 140 

BP197 - 74197 Pre-setable 50MHz binary counter . . 1-80 1-70 140 

BP19B - 74198 K-blt parallel L-R shilt register . . 6-60 500 400 

BP199 - 74199 8-bit parallel access shilt register . 5-50 5-00 400 
Devices may bo mixed to qualify lor quantity price. Larger quantities — prices on 
application ITTL 74 8eries only). 
Data Is available lor the above series of I.C's in booklet form. Price 13p. 

TTL INTEGRATED CIRCUITS 

Manufacturers' "Fall outs" — out of spec, devices Including functional units ami 
part function but classed as out of spec, from the manufacturers' very rigid specifica- 
tions. Ideal for learning about I.C's and experimental work. 



PAK Ho. 

C1C00 - 12 X 7400N 
I7IC01 - 12 x 7401 N 
UIC02 — 12 X 7402N 
flCOS - 12 X 7403N 
i;iC04 - 12 X 7404N 
I1IC06 - 12 x 7495N 
DIC10 - 12 x 7410N 
UIC20 - 12 X 7420N 
TIC40 - 12 x 7440N 



50p 
60p 
50p 



T7IC41 



PAK Wo. 

IMC42 — 3 X 74O0N 
I [(■;.(> = 12 X 7430N 
l'IC31 - 12 X 7431N 

50j> UIC60 - 12 X 7460N 

60p i:iC70*> 

60p UIC73 = 

50p VIC73 » 

50p I1C74 - 
1IC75- 



K x 7472N 

H x 7473N 

H x 7474N 

H x 7475N 

8 X 7476N 
UICX1 - 25 X Asat'd 74's 81 50 
Pake cannot lie split but 20 assorted pieces (our mix) Is available as 1'AK L'ICXI 
Erfry PAK carries out BI-PAK Satisfaction or money hack tU'ARANTEE. 



50» 



7441 \N 50p IIIC76 



PAK Xo. 

50p 1)10)0 — 5 x 7480N 50p 

50p UIC82 - X 7482N 60p 

50p U1C83 - 5 X 7483N 50p 

60p i;iCAA - 5 X 7488N 60p 

SOp U1C90 - 5 X 7490N 60p 

60p IJIC92 - 8 x 7492N 50p 

SOp 1IC93 - 5 X 7493N SOp 

SOp I l'.-'-U a. 5 X 7494N SOp 

SOp OIC98 - 6 x 7495N 50p 

60p IKIIB = .'. x 7496N SOp 



ANOTHER 

BI-PAK 

FIRST! 

THE NEW S.G.S. 

EA 1000 AUDIO 
AMPLIFIER MODULE 

GUARANTEED NOT LESS THAN 3 WATTS RMS 

Especially designed by S.G.S. incorporating their proven Linear I.C. 
Audio Amp. TA/621 providing unlimited applications for the 
enthusiast in the construction of radios, record players. Audio and 
Stereo units. Also ideal for intercom systems, monitoring applications 
and phone answering machines. OTHER USES: portable applications 
where supply rails as low as 9 V are of prime importance. 




• Sensitivity 40 mV for I watt 
VOLTAGE GAIN 40dB but 
can be varied up to 73dB for 
some applications. 

• Signal to Noise Ratio 86dB. 

Frequency response better than 
50 Hz to 25 KHz for -3dB. 

• Normal supply Voltage 9-24V. 

• Suitable for 8-16 OHM Loads. 



• Overall Size 2" • 3" V. 

# Typical Total Harmonic distor- 
tion at 1 watt less than 1%. 



'Supply vofcofre 
ISohm load. 



<V«) = 24V 



Module Tested and Guaranteed 

Quantity 1-9 10-25 

Price each f 2 63 £2 28 

Larger quantities quoted on request 

Full hook-up diagrams and complete technical data supplied free 
with each module or available separately at lOp each. 

ROCK BOTTOM PRICES—CAN'T BE BEATEN ! 

LOGIC OTL 930 SERIES IC'm 

Type fries 

to. Function 1-24 25-99 100 up 

BP93U Expandable dual 4-lnput NAND ISp lip lOp 

BP932 Expandable dual 4-lnput NAND butler 13» 12» lip 

BP933 Dual 4-input expander .... 13p Up lip 

BP933 F.xpandable Hex Inverter 13p 18» lip 

BP936 Hex Inverter 13p 12p 11* 

BP944 Dual 4-input NAND expandable buffer without 

pull-up 13p 12p lip 

BP945 Master-slave JKoiKS 25p 24p 22p 

BP946 Quad, 2-input NAND 12p lip 10p 

BP948 Master-slave J K or B9 £5p E4p 22p 

BP951 Monostable 66p 60p 55p 

BP962 Triple 3-inpul NAND 12p lip lOp 

BP9093 Dual Master-slave J K with separate clock 4 Op 38 P 35p 

BP9094 Dual Master-slave JK with separate clock 40p 38p 36p 

BP909T Dual Master-slave JK with Common Clock 40p 38p 86p 

BP9099 Dual Master-slave J K Common Clock 40p 88p 86p 

Devices may be mixed to qualify for quantity price, Larger quantity prices on 
application. (DTL 930 Series only). 

BRAND NEW LINEAR I.C't-FULL SPEC. 

Fries 
1-24 25-99 100 up 
Up 6Sp Up 
68p SOp 46p 
63p SOp 46p 



Type Ho. 

BP 201C— 8L20IC 
BP 701C— 8L701C 
BP 702C— 8L702C - 
BP 702—72702 

BP 709 —72709 
BP 709P— HA709C 
BP711— uA711 
BP741 —72741 

jjA 703C-J1A703C 
TAA283— 
TAA293 — 



Cass 


Leads 


TO-5 


8 


TO-5 


8 


TO-5 


8 


D.I.L. 


14 


D.I.I. 


14 


TO-5 


8 


TO-S 


10 


1 i.I.I. . 


14 


TO-5 


6 


TO-72 


4 


TO-74 


10 



Description 

<•• I' Amp 

OP Amp 

OP Amp Direct OP 

(l.P. OP Amp (Wide 

Band) 
High OP Amp 
High Gain OP Amp 
Dual comparator 
High Oaln OP Amp 

(Protected) 
R.F.-I.F. Amp 
A.F. Amp 
C..P. Amp 



53p 46p 40p 

SOp Up 40* 

Sip ISp 40* 

S8p SOp 48p 

76p SOp 60p 

43p SSp 87* 

70p SOp 56p 

90| 76p 70p 



All prices quoted in new pence Giro Mo. 38B-7006 
Please send all orders direct to warehouse and despatch department 



J 



P.O. BOX 6, WARE- HERTS 

Postage and packing add 7p. Overseas add extra for airmail. 
Minimum order SOp. Cash with order please. 

Guaranteed Satisfaction or Money Back 



BETTER, GET 'SET' 





BEST OFFER YET 1 
FAMOUS BC.22I 
FREQUENCY METER 

128 KHz— 20 MHz. Complete 
with valves, crystal and charts. 
ONLY £13 50. Carr. £100 
Less charts £8. carriage £1-5. Lewi 
charts & crystal £5, carriage £1-00. 



CRYSTAL CALIBRATOR 

No. 10 Crystal controlled hetero- 
dyne wave-meter covering 500 KHz — 
10 MHz (Harmonics np to 30 MHz). 
Power required 300V. D.C. 15mA. 
12v. 0-3A. D.C. Test equipment for 
62TM/RC. 

ONLY £4 25. P. £ p. 60p. 
FEW ONLY— No. 62 TM/RC 
1-5—10 Mil j £17-50. Carr. £2. 

MARCONI MIA SIGNAL GENERATOR 

lft— 310 MHz. In original transit case. £45. Carr. £2 -JO. 

AERIAL MAST 
EQUIPMENT 

SO' TELESCOPIC MASTS 
£3 75. Carr. £1. 
6' 2" Extension Sections to 
fit bottom o! above mast to 
Increase height. £1 25 each 
(any number supplied). 
86' MA8T (7—5' 2' inter- 
locking sections) with base 
plate and 12 nylon guys with 
semi-auto teneioner. 
£22 50 Carr. £2-50. 
70' MAST. Ditto.16 guvs, block 
and tackle. £45. Carr. £2-75. 

AERIAL RODS 3ft. 

Screw-In l'dla. sections. Brand New, green finish. Suitable 
lor many other uses. JO for £2. Carr. 50p. 25 for £5. Carr. 
Paid. 

R.F. ANTENNA 
TUNER (A.T.U.) 

Cylinder design 10" x 41". Pre- 
cision calibrated scale. Suitable 
for tuning most aerials for 
Increased signal strength. A must 
for serious operators for RC or 
TM. Full instructions. 
ONLY £1-75. P. 4 p. 25p. 

R.F. ANTENNA TUNER (A.T.U.) 
OPEN TYPE 

Mounted on ceramic former and feet. 

« g^ "Roller Coaster" design 16 G 

J|^iM£l silver or silver plated wheel 

4Sl^l |Hv traversing on wire on ceramic 

dH ^^9*^T former. Will handle conslder- 

fl^^^^L^-M able R.F. 

tiff In original packing. As used 

*n .«v with No. 53 Transmitter. 

ONLY £8-50. P. * P. 60p. 

No. 19 SET 

TRANSMITTER 

RECEIVER 

Rebuilt. Complete station with 
P8TJ, Cables, Mlc, Aerial, etc. 






^7^ £22 50. Carr. £3. 

No. 19 SET 50buA METERS 

Bcalod 0-000 and 0-15V. Brand new. 
Paid. (Quantity prices on request.) 



boxed £126 Post 




E.P. AMPLIFIER. To Increase 
output of No. 19 Bet. 
ONLY £8-75. Carr. £1-25. 
Instruction Book for RF Amp. 
37«p Post Paid. 

T9 SPARES 
IN STOCK 

Complete Instruction book 
with circuits for No. 19 
Equipment. 87rP Post Paid. 

HEAVY DUTY 
BATTERIES 

New In metal cases with 

carrying handles. 

6v. 85 AH 13' x 9|* x 7" 

LIQUID PRISMATIC 
COMPASSES 

2' diameter £7-50, p. 4 p. 25p 

FAMOUS TELE «F* 
FIELD TELEPHONES 

Suitable for Farms, Building 

Sites etc. Communication up 

to S miles or more. Rugged 

construction, will last a lifetime 

ONLY £575 PAIR. Carr. £1 

(Twin telephone wire for above available — ask for price.) 

Many other Ex-Goet. Surplus Equipment Heme in tlock. 

Receivers etc. In mall quantities too numerous to mention. 

Enquiries invited. LIST 25p Poit Paid. {Refundable 

aqainil purchases over £3.) 

O.W.O. Carriage charges apply to Mainland only. 

Minimum Rxpurl OrdiT £50. 



Surplus ElectronicTrading 



DRIVERS END LANE, CODICOTE, 
HITCH IN, HERTS, SG4 8TP 

Hours of business: 8-5 Mon.-Fri., 8-12 Sat. 
Telephone: Codicote 242 for appointment 

746 




SUB BOH CROC CLIPS. Red or Black, insulated 4p. 
Min. quantity, 6 pp. 3p. 

GARRARD MAG TAPE DECKS: 1 }ips, 50 v solenoid 
operated brakes, etc. Mains voltage motors £7-50 
each, pp £123. 

4|" PLANNAIR FAN8. Complete, capacitor, ex- 
equlp. 2,800 r.p.m. £3-50. pp 40p. 

ELECTRIC MOTORS. HOOVER OR CROMPTOH 

PARKINSON. 

; h.p. 1,440 r.p.m. £3-75 pp£100 
I h.p. 1,425 r.p.m. ffl-76 pp £1 25 
i h-p. 1,440 r.p.m. £2-25 pp 75p 

AUDIO C01TNECT0R8 

3 pin Din Plug . . . . . . 18p each 

5 pin Din Plug A type. B type . . ISp .. 

2 pin Din Speaker Plug lOp „ 

3 pin Din Line Socket 13p .. 
3-5mm Jack Plug Screened lOp 

Standard Jack Plug lOp .. 

Screened Standard Jack Plug* . . ISp ,. 

Stereo Jack Plug 18p .. 

Screened Stereo Jack Plug 18p .. 

pp on above items 3p. 

B.S.R. MINI AUTO-CHANGER. 
Mono Cartridge £4-75 pp 30p. 

PHONO PLUGS: Red or Black 8p each. 

MAINS NEONS. 

Red or Green. Size: 1" X 1 j' 15p, pp 3p. 

LEVER ACTION P.0.1000 TYPE SWITCHES. 
Lock 4-pole changeover Up, pp 3p. (ex-equip.) 

SCREENED PHONO LEADS 46' long. 15p. pp 3d, 

FTEZO DYNAMIC MICROPHONE 
BOkQslMppSp. 

MULLARD SCREW TERMINAL CAP 
4,500uf 84v 50p pp 13p. 

BELLING LEE 1-5 amp in-line rubber covered 
Interference suppressor 25p pp 8p. 

SOLENOIDS 12 VOLT PULL ACTION 
2*xl'x|"40ppp 8p. 

8TC SEALED RELAYS DOUBLE POLE 

CHANGEOVER 

48v 2500 Ex-equip. ISp pp 6p. 

SIEMEN8 MTNIATURB RELAY. Double pole 
changeover dust cover/base 48 v 2500 60p pp 5p new. 

8TC MINIATURE RELAY 280 fl Perspex Cover 
6-15v new, 85p pp 5p. 

GARDNER'S POTTED TRANSFORMER 0-250v 
Input: 18v 500m/n BOv 150 m/a, 6v 250 m/a Output. 
Size 3* X 2J' X 21". £1-00, pp 20p. Ex equip tested. 

TELESCOPIC AERIALS 

Chromed 7* closed 28" extended fi section ball 

jointed base 23p pp 8p new. 

MULLARD 4 DM 160 INDICATORS in plastic 
bolder/cover ex-equlp. size approx. IJ'xIJ'Xi" 
86p pp 8p. 

PRINTED CIRCUIT BOARD/19 ACY 19"s 10 OA200 
Diodes: 1 reed relay: 10 AZ 229 zenner ass. capacitor/ 
resistors. Power supply 22v 260 m/A DC. Output 
240v. AC £1 pp 20p ex-equlp. 

TOGGLE BWrrOHES. Single pole Double Throw 
ex-equip, new condition. 60p doz. pp 13p. 

FIBRE GLASS TAPE. 100 yd. roll: 3" 3J" wide 
£1 per roll pp 20p. 

PAINTON PLUG SOCKETS Type 159 series working 
voltage 350v AC/DC current max. 3 amp AC/DC 
7 pin plug & socket 60p pp lOp. 15 pin plug & socket 
£1 pp lOp. 

CASH WITH ORDER PLEASE 



FIELD 

ELECTRIC 

LIMITED 

3 Shenley Road, 
Borehamwood, Herts. 

Ajacent Elstree Mainline Station 
Tel: 01-953 6009. 



NEW 3in. SPEAKERS 15 ohm* 75p, P. .V [•■ I Op. 



BARGAIN PARCELS 141b at £1-45 plus 32 jp p.p. : 281b at 
£2 76 plus 52 Jp p.p. : 5Slb at £4-50 plus £1 25 p.p. Contain 
pots. Res, Valves, Diodes, Tagboards, Chassis, Valve- 
holders, etc. Oood value save £££s. Lucky Dip Service. 



FANTASTIC BARGAIN. New fl inch tubes. E450 4/B/Hl 
4VH, medium Persistence, green. Ideal scope tube. List 
price £6. Our price £1-40 carriage paid. 



600 it AMP METERS. Approx. 1 J" on panel with plug 
and switch ex new equip. 75p p. 4 p. paid. 

NEW HEAVY COAX CABLE dia. |« 70 ohms appn>.\. 
50ft. lengths £1-40, p. 4 p. 30p. 100 fl- lengths £2-70. 
p. & p. 50p. 

VHF AERIAL TUNING UNITS consisting of the following - 
1-H" 600 mlcro/ampmeter. 1 small 2-gang 75 PK 
capacitor. 1 various large wattage resistors for dummy 
load. Pair gears B.N.C. type sockets. Will tune 10 mtr» 
with 25/30 watts R.P. Input. Size only 61' x 41' x ft' 
Sealed. Price tl-371 p.p. 25p 



CRYSTALS AS NEW: lie llu. 5,345: 5,030; 5.005: 4.045: 
4,875; 4,840: 4,796; 4.580; 4.660; 4,520; 4,510; 2,300; 
2,206 Kc/s. 60p each plus 8p. p.p. 



S0OOP PURCHASE OF BRAND NEW CARBON RESIS- 
TORS. 10% tolerance J & } watt. Preferred values in 
packets of 10. Our price SOpper 100, 95p per 200, £155 p" 
300, 500 at £2-121. Our selection, p.p. 8p per 100 and 3Jp 
per extra 100. 



TRIMMER BARGAINS. There are 10IM-' sub-mln. air- 
spaced trimmers on board with min. wire ended Xtal. 
Brand new. No details: Contents 12 trimmers, some 
ceramic caps. Xtal frequency 3RD overtone 249 me/«- 
250 Mo/s. 265 Mc/s. No choice. 

Trimmers without Xtal — 60p per doz. plus 17tp p.p. 

Trimmers with Xtal— 75p per doz. plus 17Jp p.p. 
Also 20 PF min. brand new air spaced. 

50p per doz. plus 17Jp p.p. 



ANY HEIGHT AERIAL TUBULAR SECTIONS I' ■»» 
i 3 ft. long. Brass screw in type, copper coated and 
painted. Oood condition. 20p. p. & p. 5p each. Mlmimun. 
order 10. 



BRAND NEW HARTLEY OSCILLOSCOPES CT31B In 
original packing. Band width up to 5 Mc/s. Mains supply. 
Price £40, p. 4 p. £l-50p. 

AERIALS NEW CONDITION. Whip type 4ft. 25p, lilt 
70p, 14ft. 77Jp. Used condition 4fi 20p. 14ft. 62 jp. All 
collapsible type. P. & p. 4ft. lOp, rest at 17Jp. Bases for 
above 25p. p.p. 12Jp. New matching unit coax connection 
for above 30p, p.p. 5p. 

Huge release of valves for the 62 set TX/RX, In original 
rubber packing consisting of QV04/7 X 61M, ARP12 etc. 
10 valves In nil at the bargain price as seen 

87|ppln« 17Jpp.p. 



R209. Set of valves 62Jp. p.p. 25p. 



New Headphone and Mike rublwr muff type. L«< 
Impedance. 87 Jp, p. 4 p. 17 jp. 



NEW AERIAL WIRE ON B0ARD8 7/22 UNCOVERED. 
75(t. 40p. 90ft, 47Jp. 100ft 65p. 150ft, 75p- 180ft, 95p. 
250ft. £1 80p. p & p 20p. 

Headphones, ex Gov. DLR No. 5 low Impedance. 
New 87ip 17|p p.p. Used condition 62Jp 17Jp p.p. 

MUTRHEAD DECADE A.F. SIGNAL GENERATOR. 
This precision Instrument can be used: 

1. To Measure Gain up to 60 dbs. 

2. To Measure Loss up to 45 dbs. 

3. To compare Power levels (A.F.). 

4. As an Audio Frequency Generator covering 100 Hz 
to 41 kHz. With a dial Betting accuracy of ±0-6 Hz. 
Output :— 1 M/W Into 600 SL. Complete with malm 

power unit. Tested. Good Condition. £12, p. & p. 75p. 

ENCLOSED AERIAL RELAY COIL. Res. 700 ohms approx. 
28 watts RF DNC outlet, working voltage 12v. 76p, 
p. & p. lOp. £1 with B NC plugs. 

Also J* 76 ohm Coax in 50ft colls with BNC plugs good 
condition, price £1 + 30p. p.p. 

2 BNC plugs on short length coax cable large size low loss 
plugs SOp • 6p, p.p. 

NEW BOXED AMP METERS 1J" 20-0-20 do. 65p. 
p. & p. 5p. 

C.W.O. CARRIAGE CHARGES MAINLAND ONLY 

A. H. THACKER, 

Radio Dept., 
HIGH STREET, CHESLYN HAY. 

Nr. Walsall. Staff*. 



USED EXTENSIVELY BY INDUSTRY. GOVERNMENT DEPARTMENTS. 

EDUCATIONAL AUTHORITIES. ETC. 
• LOW COST • QUICK DELIVERY • OVER 2M RANGES IN STOCK 
• OTHER RANGES TO ORDER 



"SEW 



NEW 

CLEAR PLASTIC 

METERS 

TYPESW.IOO 
100 x80 mm. 



20V. D.C. . . £8-10 

BOV. D.C. .. 1810 

300V. D.C. £810 

lamp. D.C. £310 

6 amp. D.C. £310 

300V. A.C. £8 10 

VU Meter. . 18-75 




60/iA 18 60 

60-0-50aiA £8-45 

lOOuA 13 20 

100-0-100;jA£8-45 

BOOuA £3 35 

1mA 1810 



' DESIGNS! 

BAKELITE PANEL 
METERS 
TYPE S-80 

80 mm. 
square fronts 

60/iA £320 

B0-0-60^A is-io 

lOOttA £275 

10O-O-100jiA£310 

600uA £3 00 

1mA £2 60 

20V. D.C... £2-60 




300V. D.C. £280 
1 amp. D.C. 18-60 
fi amp. D.C. £2-80 
300V. A.C. £2 60 
VU Meter.. 18-87 



"SEW" CLEAR PLASTIC METERS 



Type MR.85P. 4±in. x 441n. bond. 



iOti\ ...... is-eo 

50-0-50fiA £8-10 

lOOfiA £3 10 

100-0-1 OOfiA £8 00 

SOOuA 23 00 

600uA .... 18 90 
50O-O-5O0uA£2-80 

1mA £2-80 

1-O-lmA . . £2-80 

6mA £8-80 

10mA .... 82-80 



60mA 

100mA 

600mA 

1 amp 

6 amp 

16 amp 

30 amp 

20V. D.C... 
BOV. D.C. . . 
160V. D.C. 
300V. D.C. 
1BV. A.C. . . 
300V. A.C. 
8 Meter 1mA £2 87 
VU Meter., i8 60 
1 amp. A.C £2 80 
B amp. A.C- £2-80 
10 amp. A.C. "£2-80 
20amp.A.C£2 80 
SO amp. A.C88-80 



£8 80 
£280 
£280 
£8 80 
£2 80 
£2 80 
£8-00 
£2 80 
£880 
£280 
£280 
£880 
£8 80 



Typa MR.52P. 2|in. iquare Ironti. 



BOuA £810 

60-O-60uA £260 

lOOuA £8 60 

100-0-100uA£2 50 

eOOuA £2 30 

1mA £8 00 

0mA £2 00 

10mA £8 00 

80mA .... £2 00 

100mA £800 

60OmA £2 00 

1 amp £8 00 

5 amp £2-00 



10V. D.C. . . £8-00 
20V. D.C. . . £8 00 
60V. D.C. . . 88-00 
300V. D.C. 88 00 
15V. A.C. . . 88-10 
300V. A.C. 88-10 
8 Meter 1mA £2 10 
VU Meter.. 88-20 
1 amp. A.C £2 00 
B amp. A.C £2 00 
10 amp. A.C£2-00 
20amp.A.C£2 00 
30 amp. A.C68 00 



Type MR.65P. 3,in. x 8,in. Ironti. 



60uA .... £8-87 
50-0-50uA £2 75 

lOOuA 82-76 

100-O-100uA£2-85 

200uA £286 

500uA £2-40 

500-0-500uA£2-20 

1mA £8-20 

6mA 12 iO 

10mA .... £2-20 

60mA £2 20 

100mA £2 20 

600mA £2-20 

1 amp £2 20 

6 amp £2-20 

10 amp 8220 

15 amp. .. 82-20 



20 amp. 
30 amp. 
50 amp. 
6V. D.C. 



£2 20 
£2 80 
£2 50 
£2 20 



£2 20 
£8 20 
£220 
£220 
£220 
£2-30 
£230 
£8 80 
£8 80 
£2-30 



10V. D.C. , 
20V. D.C. 
60V. D.C. . 
150V.D.C. 
300V. D.C. 
15V. A.C. 
60V. A.C. 
160V. A.C. 
SOOV. A.C. 
600V. A.C. 
8 Meter 1mA £2-37 
VU Meter.. 88-87 
60mA A.C. -12 HO 
100mA A.C82-20 
200mA A.C68-20 
800mA A.C. ■82-20 
lamp. A.C £2 20 
6 amp. A.C £2 20 
10amp.A.C£2 20 
20amp.A.C£2 20 
30amp.A.C£2 20 



'MOVING IRON- 
ALL OTHERS MOVING COIL 
Please add postage 

SEW EDUCATIONAL 
METERS 

Type ED.107. Size 
overall 100mm x 
90mm X 108mm. 
A new range of high 
quality moving coll 
instrument* ideal 
tor school experi- 
ments and other 
bench application". 
3' mirror scale. The 
meter movement is easily accessible to 
demonstrate internal working. Available 
io the following ranges: 




BOuA £5 00 

lOOuA £4-65 

1mA 84-40 

50-0-60uA . . . £4-66 

1-O-lmA 84-40 

lAd.c 84-40 



20V d.c. 
BOV d.c 

SOOV d.c. 



£4 40 
.£4-40 
. £4 40 



Duftl range 
500mA/5A d.c.£4-68 



BAd.c 64-40 5V/50V d.c. .. £4-66 

10Vd.c £4-40 



Type ME.S8P. 1 21/82in. iquare Ironti. 

2O0mA £1 6u 

300mA 61-60 

500mA 81-60 

750mA 81-60 

1 amp 81 60 

2 amp 61-60 

5 amp 81-60 

10 amp. . . £1-60 
3V. D.C. 
10V. D.C... 



BOuA £210 

60-0-50uA 81-80 

lOOuA £1-90 

100-0-lOOuA 11-75 

200uA 81-76 

SOOuA .... 8166 
600-0-600uA£l-60 

1mA 81-80 

1-O-lmA .. 81-60 

2mA 61-60 

5mA 61-60 

10mA .... 81-60 

20mA 61-60 

60mA 61-60 

100mA £1-60 



150mA 



81-60 



£160 
6160 
15V. D.C... 1160 



20V. D.C... 
100V. D.C. 
1B0V. D.C. 
SOOV. D.C 
6O0V. D.C. 
780V. D.C. 
15V. A.C... 
60V. A.C.. 
150V. A.C. 
SOOV. A.C. 
600V. A.C. 
8 Meter 1mA £1-70 
VU Meter.. £2.10 



£160 
6160 
6160 
6160 
6160 
8160 
81-70 
61-70 
61-70 
£170 
£1-70 



Type MR.45P. I 

60uA 82 26 

50-0-50uA 8210 

lOOuA £2-10 

10O-O-100uA£1.87 
200uA .... 81-87 

SOOuA 81-76 

60O-O-500uA 11-70 

1mA 81-70 

6mA £1-70 

10mA 61-70 

60mA 81-70 



100mA . 
600mA . 
1 amp . 



.. 81-70 
.. 81-70 
.. £1-70 



i. iquare Ironti. 
5 amp 11 70 



£160 
£150 
6160 
£180 
£180 
11-80 



10V. D.C. . 
20V. D.C . . 
50V. D.C . . 
SOOV. D.C. 
15V. A.C . . 
SOOV. AC. 
S Meter 1mA £1 85 
VU Meter.. 62-26 
1 amp. A.C £1-70 
5 imp. A.C £170 
lOamp.A.CU-70 
20 amp. A.C *£1 70 
30 amp. AC. *81 70 



•SEW" BAKELITE 
PANEL METERS 

Type MR. 65. 3j-in. iquare Ironti. 

500mA £190 

1 amp £1-90 

6 amp £1-90 

15 amp 81-80 

30 amp 61-90 

60 amp £1 90 

5 V. D.C .. 6190 
10V.D.C .. 61-90 
20V. D.C . . 61-90 
60V. D.C. . . 61-90 
150V. D.C 61-90 
SOOV. D.C. 81 90 
30V. A.C 81-96 
50V. A.C £1 95 
150V. AC 8196 
300V. A.C £1-96 
600mA A.C £195 




25uA 83 60 

60uA 82-76 

80-0-50uA £2-35 
lOOuA .... 82-86 
100-0-lOOuA £2 25 
SOOuA .... 62-80 

1mA 61-90 

1-O-lmA .. £190 

5mA 61-90 

10mA 61-90 

50mA .... £190 
100mA 81-90 



1 amp. A.C £1 96 
6 amp. A.C £1-95 
10amp.A-C*£l-95 
20amp.A.C£195 
30 amp. A.C. *£1 95 
50 amp. A.C£l-96 
VU Meter . . £810 




EDGWISE METERS 

Type PE.70. 3 17/82JD. x 1 15/821n. > 
2* in. deep. 



50uA £8 10 

5O-O-50uA 6800 
lOOuA .... £300 
100-O-100uA £2-90 
200uA £2 90 



500mA £2 76 

1mA 82-46 

300V. A.C. £8-46 
VU Meter.. 68-40 



Send lor Dlortrated brochure on SEW 

Panel Meten— dUcounta lor quantities 



MULTIMETERS for eV6M purposel 



ROUND SCALE TYPE PENCIL TESTER 
MODEL TS 68 

.-^Completely portable, simple 
to use pocket sized tester. 
Ranges 0/3/30/300V AC 
and DC at 2.000 o.p.v. 
Resistance 0-20E ohms. 
ONLY C.-97 P. 4 P. 18p. 




MODEL TE-90 50.000 
O.P.V. Mirror scale, overload 
protection. 0/3/12/60/300/600/ 
1.200 v. D.C. 0/6/30/120/300/ 
1,200 v. A.C. .08/6/6O/6O0mA. 
D.C 16K/160K71.6/16MEGO. 
-20 to +63 db. 17-60. 
P. A P. 15p. 



BKYWOOD SW-500 
BOKO/Volt. Mirror 
•sale DC Volts 
0.6/3/12/30/300/600. 
DC Current 20uA/6/ 
60OmA Resistance 
10K/100K/1 Meg/10 
Meg. Decibels — 20 
to +67 db. 1760. 
P. 4 P. 15p. 

870 WTE MULTI - 
METER 
Features A.C. current 
ranges. 20,000 o.p.v. 
0/-5/2-5/10/50/2SO/500 

1000 V DC 
0/2- 5/10/50/260/600/ 
1000 V AC 
0/oOuA/l/lO/lOOMA/l/lO 

Amp DC 
0/lOOMA/l/lOAmp AC 
0/5K/50K/S00K/5MEG/ 

60MEG. 
-20 + 62 db. 

116. P. A P. 25p. 







FTC-401 TRANSISTOR TESTER 



Full capabilities lor mea- 
suring A, B and ICO. 
NPN or PNP. Equally 
adaptable for checking 
diodes. Supplied com- 
plete with Instructions, 
battery and leads. 
68-871. P. * P. 15p. 

A076 AUDIO GEHEB- 

ATOK 
Portable, mains operated 
Sine wave 20 to 200,000 
Ha. 
Square wave 20 to 30,000 

Ha. 
Output voltage Sine 17V 
P/P. Square 21V P/P. 
Distortion less than 1%. 

617-60, P. 4 P. 37p. 



TE-20D RF SIGNAL GENERATOR 

Accurate wide range sig- 
nal generator covering 
120 Kc/s-DOO Mc/s on 
6 bands. Directly cali- 
brated Variable R.F at- 
tenuator, audio output. 
Xtal socket for calibra- 
tion. 220/240 V. A.C 
Brand new with instruc- 
tions. 116. Carr. 37 J p. 
Size 140 x 216 x 170 





BELCO DA-20 SOLID STATE 
DECADE AUDIO OSCILLATOR 



New high quality port- 
able instrument. Sine 
1 Ha to 100 KHz. 
Square 20 Hz to 20 KHz. 
Ontput max + 10 dB 
(10 K ohms). Opera- 
tion 220/240V. A.C. 
Size 215mm x 150mm x 
120mm. 
Price £27-50. Carr. 25p. 





270° WD3BA HQLE 
ImAMETEBS 
MW1-6 60mm square 
£3 97, 
MW1-8 80mm square 
£497, 
P. 4 P. extra 



TRANSISTORISED L.C.R. A.C. 
MEASURING BRIDGE 

A new portable 
bridge offering ex- 
cellent range and 
accuracy at low 
coat. Ranges: R. 
lO-ll-l megO 
6 Ranges ±1% 
L.1 u H • 111 
H ESR YS 6 Ranges2 = %C10pF± lllOmFd. 
6 Ranges ±3%. TURNS RATIO 1:1/1000- 
1:11100. 6 Ranges ±1%. Bridge voltage at 
1.000 cps. Operated from 9 volta. lOOuA. 
Meter indication. Attractive 2 tone metal 
case. Size 74 x S x 2in. 120. P. 4 P. 25p 





UM.049 MULTIMETER 

20,000 O.P.V. overload 

protection. 

0/3/30/60/300/800/3000 V 

DC. 

0/6/60/120/600/1200 V AC. 

O/SOuA/12/300 MA. DC 

0/60K/6MEG. 

- 20 + 63 db 

£4-50. P. 4 P. 15p. 

MODEL TE-12 
20,000 O.P.V. 0/0.6/6/30/120/ 
600/1.200/3,000/6,000v. D.C. 
0/6/80/120/600/1.200V. A.C 
0/60uA/6/60/600mA. 0/6K/. 
600K/6Meg./60 Meg. O 60pF. 
0.2mFd. £6-97,. P. 4 P. 17,p. 

Tire MODEL TW-50K 46 
ranges, mirror scale, 50K/Vol. 
D.C 5K /Volt A.C. D.C: 
Volta -125, -25, 1-25, 2-5, 5, 10. 
25, 60. 126, 250, 500, 1000V, 
A.C. Volta: 1-5, 3, 6, 10, 26. 
50, 125. 260. 500, 1000V. D.C. 
Current: 26. 60uA, 2-5, 5, 28. 
60, 250, 600mA, 5, 10 amp. 
Resistance: 10K, 100K, 1 MEG. 
10 KEOQ. Decibels: -20 to 
+81-5 dB. 1860. P. 4 P. 17,p 

HT100B4 MULTI- 
METER 
Features A.C current 
ranges. 100,000 o.p.v. 
Mirror Scale, Overload 
protection. 
0/- 5/2 -6/10/50/250/500/ 

1000 VDC 
0/2-6/10/60/250/1000 V 
AC 
0/10/250UA/2-5/25/250 

MA/10 Amp DC. 
10 Amp AC. 
0/20K/200K/2MEG/20 

MEG. 
-20 + 62 db. 

112-60. P. 4 P. 25p. 

RUSSIAN 22 RANGE MULTIMETER 

Model U437 10.000 o.p.v. 
A first class versatile in- 
strument manufactured in 
UR.S.R. to the highest 
standards. Ranges: 2-5/10/ 
60/230/500/lOOOv D.C 2-6/ 
10/30/250/600/ 100v/ AC 
DC Current 100 wA/1/10/ 
100mA/ 1 A. Resistance 

300 ODB18/3/30/300K/3M CI. 
Complete with batteries. 
test leads, instructions and 
sturdy steel carrying case. 
OUR PRICE £6-97 P. 4 P. 
25p. 

TO-3 PORTABLE OSCILLOSCOPE 

3in. tube. Y amp. Sensiti- 
vity 0-lv p-p/CM. Band- 
width 1-5 cps-1-5 MHz. 
Input Imp. 2 meg Q 26pF 
X amp. sensitivity 0-9v. 
p-p/CM. Bandwidth 1.5 ops 
-800KHz. Input imp. 2 
meg fl 20pF. Time base. 
5 ranges 10 cps-300 KHz. 
Synchronization. Internal/ 
external. Illuminated scale 140 x 216 x 330 
mm. Weight 15) lb. 220/240V. A.C. Supplied 
brand new with handbook. £87-60. Carr. 50p 

HONEYWELL 
DIGITAL 
VOLTMETER 
VT.100 







Can be panel or bench mounted. Basic meter 
measures 1 volt D.C but can be used to 
measure a wide range of AC and DC volt, 
current and ohms with optional plug in cards. 
Specification: Aocuracy: ± 0.2, ± 1 digit. 
Resolution: lmV. Number of digits: 3 plus 
fourth overrange digit. Over-range: 100% 
(up to 1-999) Input impedance: 1000 Meg 
ohm. Measuring cycle: 1 per second. Adjust- 
ment: Automatic zeroing, full scale adjust- 
ment against an internal reference voltage. 
Overload: to lOOv. D.C Input: Fully floating 
(3 poles). Input power: 110-230v. A.C. 
00/60 cycles. Overall size: 5}in. x 2 13/16in. 
x83/16in. 

AVAILABLE BRAND NEW AND FULLY 
GUARANTEED AT APPROX. HALF 
PRICE 

£49-97| Carr. 50p. 




747 



SEMI-CONDUCTORS/VALVES 

ALL DEVICES BRAND NEW AND FULLY GUARANTEED 



Transistors 



.•0301 

2OS02 

2G303 

2G306 

'2G30S 

2G309 

2G371 

20 374 

2G381 

2X3SSA 

2X404 

2X696 

2X697 

28698 

2X699 

2X706 

2X706A 

2N708 

2N709 

urns 

2X718A 

2N726 

2X727 

2X914 

2X916 

mu 

2X929 
2X930 
2X937 
2X1090 

2X1091 
2N1131 
2X1132 
2X1302 
2X1303 
2X1304 
2X1305 
2X1306 
2X1307 
2N1308 
2X1309 
2X1507 
2X1613 
2X1631 
2X1032 
2X1637 
2X1638 
2X1639 

2X1701 ie?p 

S4p 



17p 
ISp 

m 
ah 

Mi 



m 

BSp 

18 p 



ISp 

Mb 
Hi 

25p 

ISp 

lop 

lap 
18p 
10p 
lOp 

m 

10p 
lOp 
12p 
10p 
lOp 
lOp 
lOp 



2X1711 

2X1893 

2X2147 

2X2160 

2X2193 

2X2 193 A Up 

2X2194 27p 

2X2194A 30p 

2X2217 25p 

2X2218 20p 

2X2219 " 

2X2220 

2X2221 

2X2222 

2X2222A SSp 

2X2297 80p 

2X2368 15p 

2X2369 15p 

2X2369A 15p 

2X2410 42p 

2X2483 ' 

2X2484 

2X2539 

2X2540 

2X2613 

2X2614 

2X2646 

2X2711 

2X2712 

2X2713 

2X2714 

2X2904 

2X2904A Mp 

2X2905 25p 

2X2905A 20p 

2S2906 SOp 

2X2906A Z5p 

2X2907 23p 

2X2023 lBp 

2X2924 15p 

2X2925 15p 

2X2926G 12p 

2X29260 12p 

2X2926Y 12p 

2X3011 20p 

2X3014 " 

2X3053 

2X3054 

2X3055 

2X3133 

2X3134 

2X3135 

2X3136 

2X3390 

2X3391 

2N3391A 80p 

2X3392 17p 

2X3393 " 

2X3394 

2X3402 

2X3403 

2X3404 

2X3403 

'.'h'3414 



37r. 
~2p 
57 P 



20 P 

epj 

25c 
20p 



25p 
SOp 

•!9p 

m 

25 r 

SOp 
Bta 

25p 
25p 
Mp 



lit 

IS; 

22- 
32p 
55p 
22c 



2X3415 22p 
2X3416 27p 
2X3417 87p 
2X3439 ISOp 

m% 9 

2X3565 
2X3566 
2X3568 
2X3569 _ 
2X3570 128p 
2X3572 97p 
2X3005 
2X3606 

2N8607 

2X3638 - 
2N3638A SOp 
2X3641 18p 
2X3012 
2X3643 
2X3644 
2X3645 
9.NS69I 
SXS692 
2X3693 
2X3694 
2X3702 
2X8703 
2X3704 
2X3705 
2X3706 
2X3707 
2X3708 
2X37H9 
2X3710 
2X3711 _ 
2X3713 187p 
2X3714 200p 
2X3715 220p 
2X3716 285p 
2X3773 S40p 
2X3791 275p 
2X3819 84p 
2X3H20 55 p 
2X3823 60p 
2X3864 27p 
2N3854A 27p 
2X38S5 27p 
2X3855A 80p 
2X3866 80p 
2X3856A 35p 
2X3858 28p 
2HMM4 30p 
2X3859 27p 
2X3669A 32p 
2X3860 80p 
2X3866 160p 
2X3877 40p 
2X3877A 40p 
2X3900 87p 
2X3900A 40p 
2X3901 87p 
2X3903 
2X3904 
2X3905 
2X3906 
2X4008 
2X4059 

2X4060 
2X408] 

2X4062 
2X4244 
2X42-18 
2X4249 
2N4280 
2X42S4 
2X4255 
2M4284 

■ 
2X4288 
2X4287 

2X4289 

2X4290 

2X4291 

2X4262 

2X4494 

2X4303 

2X4964 

2N4965 

2X5027 

2X5U2S 

2X51)29 

2X5030 

2X5172 

2X6174 

2X5175 

2X8176 . 

2X5232A 80p 

2X5243 46p 

2X5246 42p 

2X5249 87p 

2X5265 825p 

2X5305 87p 

2X5306 ' 

2X8807 
2X6308 
2X5809 

2X5310 
2X0364 
2X6355 
2X5356 
2X5365 
2X5306 
2X6367 
2NH07 



M I 

26p 

Ml 

25 P 

)Ap 

10p 
12,. 
12p 

Up 

m 

ir.p 
18pi 

lRp 
42p! 
42p, 
17p, 
17p 
17pl 
17p 
15p 
Up 

Up 

lop 

Up 

17p 
•ft 

lip 
18p 
52 p 
57p 
47p 
42 p 
18p 
Up 
Up 
Mi 



Mp 

37p 
37p 
62p 

Ma 

27p 

m 

Up 

47p 
32p 
57p 

Ml 



2N..4.- 

2S5459 

28102 

28103 

28104 

28301 

28302 

28303 

28304 

2S501 

2S602 

28503 

3X83 

3N128 

8X140 

3H141 

3X142 
3N143 
3X162 
-Hirt.Ml 
40260 
40261 
40309 
40310 
40311 
40312 
40314 
40316 
40316 
40317 
40319 
40320 
40323 
40324 
40328 
40329 
40344 
40347 
40348 
40380 
40361 
40362 
40370 
40406 
40407 
40408 
40409 
40410 
40412 
40487 A 
40468A 
40328 
40600 
40003 
AC107 
AC128 
AC 127 
AC128 
AC161 
AC162 
AC164 
ACI76 
AC187 
AC 188 
ACY17 
ACY18 
ACY19 
ACY20 
ACY21 
ACY22 
ACV2M 
ACY39 
ACY40 
ACY41 
ACY44 
HIM" 
A0149 
AD150 
AD161 
AD162 
AF109 
AF114 
AF115 
AF116 
AF117 
AF118 
AK121 
AFI24 
AF125 
AF126 

unset 

AF139 
AF178 
AFI79 

Al'IMI 

AF181 

AF186 

AF239 

AF279 

AF280 

AFZI1 

A8Y28 

ASY27 

ASY28 

A8Y29 

A8Y50 

ABYSl 

ASY84 

ASV67 

ABY88 

A 87.21 

ACY10 

BC107 

BC108 

BC109 

ncin 



35p 
40p 
25p 
25p 
25p 
60p 
SOp 
60p 
75p 
32p 
85p 
27p 
40p 
70p 
77p 
72p 
S6p 
87p 
87p 
55p 
SOp 
32p 
32p 
4Sp 
8Sp 
47p 
87p 
87p 
47p 
37p 
SSp 
47p 
32p 
47P 
37p 
30p 

I7| 

57p 

Up 

40p 
40 p 
50p 
32p 
57p 
40p 
Ml 

65p 

Mb 

50p 
57p 
35p 

■::■-? 

67p 
SOp 
30p 
20p 

Mi 

2 Dp 
18p 
22p 
22p 
20p 
25 1 
25p 
27p 
24 1 

24 p 
20p 
20p 
lOp 
lft 
47p 
1«S 
15p 
25p 
47p 
47p 
C2p 
35p 
3S; 

Mb 

25p 

Hi 

25p 

Mi 

44p 

30p 

Mi 

iflp 

18p 
Up 

all 

Up 

45p 
60p 

40p 

Mi 

30 p 
47p 

47„ 

Ml 
H| 
M| 
Ml 

27 P 

25 p 
32p 
25 P 
45 P 

Mi 

51 1 
IMl 

10p 
10p 
lOp 

M| 



IK 114 
BCUS 
BC116 
BC118 
BC119 
BC121 
BC122 
BC125 
BC126 
BC1S4 
BC135 
BC188 
BC137 

Bcifta 

BC140 
BC141 
BC147 
BC148 
BC149 
UC152 

BCUS 

BC1S4 
BC157 
BC158 
BC169 

Hi 160 

BC167 

BC16SB 

BC168C 

BC169B 

BC169C 

BC170 

BC171 

BC172 

BC176 

BC177 

I1C178 

BC179 

BC182 

BC182L 

BC183 

BC183L 

BC184 

BC184L 

BC186 

BC187 

BC212L 

BC213L 

BC214L 

BCY10 

BCY30 

BCY31 

BCY32 

BCY33 

BCY34 

BCY38 

BCY39 

BCY40 

BCY41 

BCY42 

BCY43 

BCY54 

BCY58 

BCY69 

BCY60 

BCY70 

BCY71 

BCY72 

BCY78 

BCY79 

BOZ10 

BCZ11 

BD112 

BD116 

BD121 

BD123 

BD124 

BD131 

BD132 

BDY10 

BDY20 

BDY61 

BDY62 

BF115 

II II 17 

BF152 

BF154 

BF158 

BF169 

BF163 

BF167 

BF170 

BF173 

BF177 

BF178 

BF179 

BF180 

BF181 

BF182 

BF184 

BF-18S 

BF194 

BF195 

BF196 

BF197 

BF198 

BF200 

BF224 

BF225 

BF237 

BF238 

BF244 

BFW61 

BFW87 

BFW88 

1IFW89 



15p HFWI.ii 
16p|BFW91 
ISp BFX12 



lag 


BFX13 


S2p 


30p 


BFX29 


SSp 


SOp 


BFXSO 


SSp 


Mb 


BFX37 


SOp 


ISp 


BFS4* 


37p 


Ml 


BFX68 


67 o 


Up 


BFX84 


SSp 


12p 


BFX85 


SOp 


ISp 


BFX86 


25p 


15p 


BFX87 


S5p 


Mb 


BFX88 


20p 


3Sp 


BFX89 


62p 


3Sp 


BFX93A 


70p 


lOp 


BFY11 


42p 


lOp 


BFY18 


25p 


12p 


BFY19 


25p 


17p 


BFY21 


4Sp 


Mb 


BFY24 


4Sp 


Mb 


BFY29 


40p 


ISp 


BFY30 


40p 


Up 


BFY41 


SOp 


12p 


BFY43 


62p 


Mb 


BFY50 


SOp 


lip 


BFY51 


SOp 


12p 


BFY52 


SOp 


ISp 


BFY53 


ISp 


14p 


BFY56A 


67p 


ISp 


BFY76 


42p 


12p 


BFY77 


S7p 


ISp 


BFY90 


esp 


ISp 


B8X19 


17p 


22p 


BSX20 


15p 


Mb 


BSX21 


SOp 


Mb 


BSX26 


4Sp 


Mb 


B8X27 


47p 


12p 


B8X28 


32p 


lOp 


BSX60 


82p 


9p 


BSX61 


62p 


8p 


B8X76 


ISp 


Up 


B8X77 


20p 


lip 


B8X78 


2Sp 


25p 


BSY24 


ISp 


27p 


B8Y25 


ISp 


ISp 


B8Y28 


17p 


12p 


B8Y27 


ISp 


ISp 


BSY28 


17p 


27p 


B8Y29 


17p 


SOp 


BSY32 


S6p 


40b 


BSY36 


SSp 


SOp 


BSY37 


SSp 


SOp 


BSY38 


SOp 


8Sp 


BSY39 


22p 


4Sp 


BSY43 


SOp 


Mb 


BSY51 


32p 


SOp 


BSY52 


82p 


ISp 


BSY53 


37p 


Mb 


BSY54 


40p 


15p 


BSY56 


SOp 


32p 


BSY79 


45p 


22p 


BSY90 


S7p 


22p 


BSY93A 


12p 


97p 


C424 


ISp 


ISp 


C450 


ISp 


20p OET102 


SSp 


ISp 


GET113 


2&p 


SOp 


GET114 


SOp 


80p 


GET118 


SOp 


27p 


GET120 


25p 


40p 


GET873 


12p 


SOp 


GET880 


4&p 


ll£p 


GET887 


ISp 


65 p 


GET889 


22p 


80p 


OET890 


22p 


7Bp 


GET896 


22p 


75p 


GET897 


2Sp 


Mi 


(■KT-ys 


22p 


12Sp 


MAT100 


2Sp 


105p 


J1AT101 


25p 


125p MAT 120 


25p 


lOOp 


MAT121 


25p 


2Sp 


MJ400 


107p 


47p 


MJ420 


SOp 


SSp 


MJ421 


80p 


20p 


MJ430 


102p 


ISp 


MJ440 


SSp 


S5p 


MJ480 


97p 


SSp 


MJ481 


125p 


26s 


MJ490 


lOOp 


Ma 


MJ491 


137p 


SOp 


MJE340 


SOp 


SOp 


MJE370 


80p 


25p 


MJE371 


80p 


SOp 


MJE520 


75p 


SSp 


MJE521 


70p 


SSp 


MPF102 


42p 


SOp 


MFF103 


35p 


20p 


MPF104 


87p 


20p 


MPF105 


87p 


15p 


MPS3638 32p 


ISp 


XKT124 


42p 


ISp 


XKT125 


27p 


ISp 


XKT126 


27p 


ISp 


XKT128 


27p 


SSp 


XKT135 


27p 


14p 


XKT137 


S2p 


19p 


XKT210 


30p 


22p 


XKT2U 


SOp 


22p 


XKT212 


30p 


SSp 


XKT213 


30p 


47p 


XKT214 


20p 


S5p 


XKT215 


22p 


28p XKT2IB 


3&P 


M| 


X K T2 1 7 


40p 



NKT2IU 30p 

XKT223 27p 

XKT224 SSp 

XKT225 SSp 

XKT229 SOp 

XKT237 8Sp 

XKT238 SSp 

XKT240 87p 

XKT241 87p 

XKT242 20p 

XKT243 62p 

XKT244 17p 

XKT245 SOp 

XKT261 SOp 

XKT262 SOp 

XKT264 SOp 

XKT271 20p 

XKT262 SOp 

XKT274 SOp 

XKT275 SOp 

XKT278 Mp 

XKT281 27p 

NKT401 87p 

XKT402 BOp 

MKT403 76p 

XKT404 SSp 

NKT40B 7Bp 

XKT406 BSp 

XKT4S1 Up 

KKT462 8Sp 

XKT463 47p 

XKT713 SOp 

XKT717 Up 

XKT784 87p 

XKT738 36p 

XKT773 SSp 

XKT781 SOp 



OC16 

0C1B 

OC20 

0C22 

0C2S 

OC24 

OC25 

0026 

OC28 

0029 

OC3B 

OC36 

OC41 

OC42 

OC44 

OC45 

OC48 

OC70 

OC71 

OC72 

OC73 

OC74 

OC76 

OC76 

OC77 

OC78 

0C81 

OCH1D 

OC82 

OC82D 

OC83 

OC84 

OC139 

OC140 

OC170 

0C171 

OC200 

OC201 

OC202 

OG203 

OC204 

OC20B 

OC206 

OC207 

OCP71 

0KP12 

ORP60 

0RP61 

P346A 

ST140 

8T141 

TIS34 

TIS43 

TI844 

T1845 

TI840 

TOW 

TI848 

TI849 

T1860 

TI8S1 

TIS52 

TI853 

XB112 

XC141 

ZTX107 

ZTX108 

ZTX109 

ZTX300 

ZTX301 .. 

ZTX302 SOp 

ZTX303 SOp 

ZTX304 Mp 

ZTX600 ISp 

ZTX601 ISp 

ZTX502 SOp 

ZTX803 17p 

ZTX604 40p 

ZTXSJI S5d 



SOp 
37 p 
8Sp 
BOp 
SOp 
SOp 
40p 
SBp 
BOp 
60p 
SOp 

eop 
SSp 
40p 
16p 
ISp 
ISp 
ISp 
ISp 
ISp 
80p 
SOp 
SSp 
SSp 
40p 
SOp 
SOp 
SOp 
SSp 
ISp 
SSp 
SBp 
SBp 
40p 
SBp 
80p 
40p 
76p 
80p 
40p 
40p 
7Sp 
95p 
76p 
Up 
SOp 
40p 
42p 
S2p 
ISp 
SOp 
6Sp 
40p 
12p 
ISp 
ISp 
ISp 
ISp 
ISp 
ISp 
lOp 
lip 
SSp 
ISp 
SSp 
ISp 
ISp 
ISp 
ISp 
ISp 



Integrated 
Circuits 

CA3000 180p 

CA3005 117p 

CA3007 86Sp 

CA3011 76p 

CA3012 88p 

CA3013 lOSp 

CA3014 184p 

CA3018 84p 
CA3018A 

nop 

CA3019 84p 
CA3020 18Bp 
CA3020A 

ieop 

CA3021 16Sp 
CA3022 130p 
CA3023 126p 
CA3026 lOOp 
CA3028A 74p 
CA3028B 

105p 
CA3029 87p 
CA3029A 

166p 
C A 3030 137p 
CA3036 122p 
C A 3036 78p 
CA3039 82p 
CA3041 109p 
CA3042 lOBp 
CA3043 187p 
CA3044 ISOp 
CA304S ISSp 
CA3046 Sip 
CA3047 187p 
CA3048 S04p 
CA3049 ISOp 
CA3060 IMP 
CA30B1 134p 
CA80B2 18Bp 
CA3063 48p 
CA3054 109p 
CA3055 840p 
CA3059 ISSp 
CA3064 ISOp 
FCB10I Mp 
FCII111 105p 
FCH121 105p 
FCH131 SOp 
FCH141 lOSp 
FC11151 lOSp 
FCH161 SOp 
FCH171 105p 

FCH181 lOSp 
FCU191 105p 
FCH201 180p 
FCU211 ISOp 
FCH221 180p 
FCH231 ISOp 
FCJ101 180p 
FCJ111 ISOp 
FCJ121 876p 
FCJ131 E76p 
FCJ141 SSBp 
FCJ201 lOOp 
F0J211 87Sp 
FCK101 480p 
FCL101 E80p 
FCY101 lOSp 



FJH1U1 


SSp 


FJH111 


?0p 


FJH121 


SAP 


FJH131 


Hf 


FJH141 


SSp 


FJH151 


SSp 


FJH161 


.•Op 


FJH171 


Sbp 


FJH181 


V-'ip 


FJH221 


SSp 


FJH231 


Stip 


FJH241 


Mb 


FJH251 


Shp 


FJJ101 


SOp 


FJJ111 


Blip 


FJJ121 


HOp 


FJJ131 


KOp 


FJJ141 


1Mb 


FJJ181 


7&P 


FJJ191 


Hhp 


FJJ211 


imi 


FJJ251 


ISbp 


FJL101 


1Mb 


FJY101 


SSp 


IC10 


250p 



1C12 
L900 
L914 
L923 



250p 
40p 

Mb 

40p 



SOp 
SOp 
SOp 
SOp 
30p 
40p 
40p 
45p 
46p 
87p 
33 p 
87p 
87p 
87p 
87p 
87p 
SSp 



MC724P 60p 
MC780P E47p 
MC788P 148p 
MC760P 184P 
HC762P Mp 
MC799P 68p 
MC1S03L 

lOOp 
MC1304P 

225p 
MC1305P 

386p 
MC838P 

649p 
MC1435P 

345p 
MC1552G 

461p 
MC1709CG 

94p 
MFC4000P 

7Sp 
PA222 S60p 
PA230 140p 
PA234 98p 
PA237 SlOp 
PA246 ISOp 
PA424 2MB 
PA264 190p 
PA266 SOOp 
8X7400 SOp 
8X7401 20p 
8X7402 Mp 
8X7403 SOp 
8X7404 SOp 
8X7405 SOp 
8X7408 80p 
3X7408 SOp 
8X7409 Mp 
8X7410 SOp 
8X7411 2Sp 
8X7413 80p 
8X7420 SOp 



SS743U SOp 

SN7440 SOp 
8X7441 AX 

75p 
8N7442 76p 
8X7446 lOOp 
8X7447 IMp 
SN7448 ISSp 
8S7450 Mp 
8X7451 
8X7453 
8X7454 
8X7460 
8X7472 
8X7473 
3N7474 
8N7475 
8N7476 
8N7483 
8X7486 
SS7490 
SS7492 
8N7493 
8S 7495 
3X7496 
8S7410 - , 
8S 74153 

140p 
8X74154 

SSOp 
8S 74160 

180p 
8X74161 

S60p 
8S 74164 

SSOp 
SS 74166 

S25p 
8K74192 

176p 
8S 74193 

17Sp 
TAA241 

ISSP 
TijU42 

42Sp 
T.'.A243 ISOp 
T ■ A26:i 75 p 
T.'.A293 87p 
T.'^300 176p 
TAA310 IMp 
T.'-A320 72p 
TAA350 17Sp 
T-'.A435 147p 
TAAS21 lUp 
T.'-A522 860p 
T-'.A530 4flSp 
T--.A-I I 44Sp 
T'-BlOl 97P 
TAD 100 ISOp 
TAD110 ISOp 
3L403D ISOp 
31702C 147p 
C.V702A S80p 
CA702O 77p 
U.1703C 187p 
Cil709C 126p 
UA710C 185p 
UA716 187P 
TJA7280 168p 
Ua730C ISOp 
UA741C 87p 



BRIDGE 
RECTIFIERS 
PLASTIC 
ENCAPSULATED 

600 PIV 1A SOp 

60 PIV 2 A Mp 

100 PIV 2 A 60p 

200 PIV 2A SSp 

400 PIV 2A 75p 



50 PIV 4A 
100 PIV 4 A 
200 PIV 4 A 
400 PIV 4 A 

50 PIV CA 
100 PIV (A 
200 PIV (A 
400 PIV t A 



SOp 
70p 
70p 
7Sp 
SSp 
7Bp 
7Sp 
lOOp 



SDLICOM RECTIFIERS 

mHIATDRE WIRE EXDED PLASTIC 

nr pl ex 

SERIES SERIES SERIES 

1 AMP IS AMI' 3 AMP 

7p Sp 19p 



4001 BOPIV 

4002 100PIV 

4003 200PIV 

4004 400PIV 

4005 600PIV 

4006 800PIV 

4007 1000PIV 

60+ less 15 



9p 
lOp 
lOp 
ISp 
ISp 
ISp 



100+ leas 20% 



20p 
SSp 
SSp 
SSp 
S7p 
SOp 



100PIV 
200PIV 
400PIV 
600PIV 
800PIV 
1000PIV 



SILICON RECTIFIERS 
STUD MOUNTING 
6A 10A 17-5A 



SSp 
SOp 



85p 
40p 



45p 
SOp 
SSp 
SOp 
75p 
85p 



50+ less 16% 100+ le 



SOp 
Slip 
8i!p 

7I!p 
8>p 
SI 05 

s ■:(>', 



35 A 
SI 88 
£1-42 
Sl-77 
£81S 
£247 



ZENER DIODES 
400MW I 1-5 WATT | .OWATT 
3-3-33 V 2-4—100 ! -9 — 100V 

lOp each I Mp each I 40p each 
25- less 15% 100+ less 20 % 

TRANSISTOR DISCOUNTS:- 12 + 10%; 
25 + 15% ; 100 + 20% any one type. Post- 
age on all Semi Conductor? 7p « xtra. 
S A.E FOR FULL LISTS 



0A2 

0B2 

0Z4 

1 1. 1 

I BS 

183 

IT4 

II"-* 

1U5 

2D21 

3Q4 

334 

3V4 

6R4 

5U4 

6V4 

8Y3 

6Z4G 

8/30L2 

6AC7 

6A07 

6AK6 

6AK6 

6AL8 

6AM6 

OAQS 

6A88 

6AT6 

8AU6 

0AV6 

6BA6 

• -)•- 1 :■. 

6 II II' i 

6BJ8 

6BQ7A 

6BR7 

8BR8 

6BW0 

8BW7 

6BZ8 

604 

60D6 

6CL6 

60 W4 

6F1 

6F6G 

6F13 

6F14 

6F18 

6F18 

8F23 

6H6 

0J4 

6J3 

6JJ0T 

6J6 



6J7 

6K8G 

6L60T 

8LD20 

6Q7 

8SA7 

68Q7 

68J7 

63K7 

68L7 

68N7 

68Q7 

6U4 

6V8G 

6V6GT 

6X4 

6X6G 

6X8GT 

1002 

10F1 

10P13 

10P14 «1-10 

12AT8 SOp 

12AT7 

12AU7 

12AX7 

12AV6 

12BA6 

12BE6 

12BH7 

19AQB 

20D1 



38p 
46p 
SOp 
SOp 
40p 
30p 
SBp 
80p 
SOp 
SSp 
SOp 
SBp 
48p 
7Bp 
SSp 
45p 
40p 
40p 
8(1 u 
40p 
40p 
SBp 
SOp 
SOp 
30p 
38p 
40p 
8Sp 
SSp 
SOp 
SSp 
SOp 
7Sp 
SOp 
40p 
90p 
70p 
8Sp 
80p 
40p 
83p 
IMp 
SOp 
6Bp 
SSp 
SBp 
4Bp 
70p 
SSp 
SOp 
85p 
17p 
SOp 
SBp 
80p 
SOp 
Mp 
40p 
4Bp 
SOp 
40p 
40p 
40p 
40p 
40p 
36p 
SSp 
40p 
SBp 
SSp 
82p 
SSp 
80p 
40p 
BOp 
7Sp 

eop 



VALVES 

30p 

42p 

»p 

80p 
90p 
BOp 
85p 
75p 



26Z4 

26ZB 

25 Z6 

30015 

30C17 

30C18 

30F5 

30FL1 

80FL12 IMp 

30FL14 9Sp 

30L1.' 



EL95 86p 

EM60 Mp 

EM81 SOp 

EM34 SSp 

EM85 £1-00 

EM87 70p 



30L17 

30P12 

30P19 

30PL1 

30PI.13 

30FL14 

38 L6 

35W4 

35Z4 

38ZS 

80B5 

80C5 

80 

8BA2 



1625 

5763 

6146 

AZ3I 

CY31 

DAF91 

DAF96 

DF91 

DF96 

DE9I 

DK92 

DK96 

DL92 

DL94 

DL96 

DM70 

DY86 

DY87 

E88CC lOOp 

E180F lOOp 

KA1SC80 Mp 

EAF42 Mp 

EB91 

EBC41 

EBC81 

EBF80 

EBF83 

EBF89 

EBL21 

EC88 



85p 
SOp 
SOp 
85p 
75p 
93p 
90p 
SOp 
35 p 
35p 
SOp 
SOp 
50p 
SSp 
SOp 
5 Op 
Mi 
70p 
160 
55p 
35p 
30p 

Up 

22p 
45p 
4op 
5Sp 
50p 
35p 
48p 
-ISp 

M| 

32p 



EY51 
EY86 
EY87 
EZ40 
F.Z41 
EZ80 
EZ81 
GZ32 
GZ34 



40p 
40p 
42p 
SSp 
Mp 
87p 
SSp 
48p 
SOp 



KT66 MM 
KT88 £2 00 
MC14 76p 
PABC80 40p 
1PC86 SOp 

PC88 
PC97 
PC900 
PCC84 
PCC86 
PCC88 
PCCS9 



60p 
45p 

48p 
40p 
40p 
BSp 
60p 
PCC189 Mp 



20p 
55p 

30p 

m 

4. Op 
32p 
60p 
60p 
60p 
65p 



PCF80 
PCF82 
PCF84 
PCF86 

PCF800 80p 
PCF801 SOp 
PCF802 SOp 
PCF805 80p 
PCF806 70p 
PCF808 75p 
PCL82 86p 
PCL83 
PCL84 
PCL85 
P0LS6 
PFL200 BSp 
PL36 BSp 



80p 
34p 
SOp 
BOp 



Mp 
4Sp 
40p 
46p 



EC88 

ECC40 

ECC84 

ECC85 

ECC88 

ECF80 

ECF82 

ECF86 

ECH21 

ECH35 lOOp 

ECH42 7Sp 

ECH81 

ECH83 

ECI.80 

ECL82 

ECL83 

EOL36 

EF37A ISOp 

EFS9 50p 



SOp 
45p 
45p 
88p 
70p 
40p 



PL81 

PL82 

PL83 

PLS4 

PL500 

PL504 

PY32 

PY33 

PY80 

PY81 

PY82 

PY83 

PY38 

PY800 

PY801 

U25 

U26 

TJ50 

L"52 

U191 

U281 

U282 

U301 



BOp 
4&p 
48p 
40p 
76p 
80p 
BSp 
S8p 
40p 
SOp 
SSp 
SSp 
40p 
40p 
SOp 
Mp 
Mp 
40p 
Mp 
75p 
40p 
40p 
40p 



20F2 
20L1 
20P1 
20 P3 
20 P4 
20P6 
26L6 



30p 
30p 
30p 

Ml 
M| 

40p 

45p 

35p 

50p 

SSp 

£1-10 

50p 

SOp 

SI -10 

£1-20 

SOp 



EF40 

EF41 

EF42 

EF80 

EF85 

EF86 

EF89 

EF91 

EF92 

EF183 

EF184 

EH90 

EL34 

EL33 

EL41 

EL42 

EL81 

EL84 

EL83 

EL91 



SOp 
SSp 
70p 
S5p 
85p 
SOp 
Mp 
SOp 
SSp 
35p 
SSp 
40p 
SOp 
£125 
60p 
SSp 
SSp 
SSp 
43p 
3Sp 



,U801 £1-80 
j UABC80 40p 

UAF42 SSp 

UBC41 

UBC81 
! UBF80 

PBF89 

UOC84 
,UCC85 

UCF80 

UCH21 
i UCH42 
' UCH81 
IUCL82 

UCL83 
IUF41 



UF80 
HF85 
UF89 
UL41 

Ci.^-l 
CY41 
UY85 



BOp 
40p 
40p 
86p 
49p 
40p 
BSp 
SOp 
70p 
40p 
35p 
SOp 

eop 

86p 
40p 
40p 
SSp 
40p 
48p 
40p 



VR 105/30 38p 
VR1S0/30 88p 
Add lip in t 
for pottage 



DIODES & 

1X34A 10b 

1N914 

1NB16 

AA119 

AA129 

AAZ13 

AAZ1S 

BA100 

BA102 

BA110 

BA111 

BA112 

I'. All.-, 



BA141 
BA142 
BA144 

li*r 



7p 

I Op 

ft 

lOp 
lOp 
lOp 
15p 
SOp 
25 p 
27p 
70p 
7p 
32p 
32p 
12p 

Ml 



RECTI 

BA154 
BAX13 
BAX16 
IJAY31 
BAY38 
BY100 
BY103 
BY122 
BY124 
BY126 
BY127 
BY164 
BY210 
BYZ11 
BYZ12 
BYZ13 
UVZI6 



FIERS 

12piGJ7M 

ISp 0A5 

7p 1 0A6 

7p,OA10 

15p 0A9 



OA47 

OA70 

OA73 

OA79 

OA81 

OA8S 

0A90 

0A91 

0A9S 

OA200 

OA202 

OA210 



87p 

MP 

12p 

SBp 

lOp 

lOp 

lOp 

lOp 

lOp 

8p 

7p 

8p 

7p 

7| 

7» 

lOp 

17p 



*■ See previous page 



G.W. SMITH & Co. (RADIO) LTD. 



See opposite page •* 



748 



M-ff£4WPM£Nr 

SAVE MP TO 

33^% OR MORE 

SEND S.A.E. FOR 
DISCOUNT PRICE LISTS 
AND PACKAGE OFFERS! 




RECORD 






DECKS 

B.8.B. 1 


SjS 




Mini Munof M 97 






OaSM £8-70 






MP60 £1075 








GARRARD 




510 11185 


A 40 11* 


£8 40 


310 1885 


2025 T/C* 


£860 




3500* 


£976 




8P25 III 


£1050 


MP60 T.P.D.2 


A70I1 


£1197 


£15 85 


8L65B 


£13 45 


810 T. P.D.I £80 87 


AP76 


£18 90 


510 T.P.D.I. £18-75 


S 1,7 2 is 


£23 95 


S10 Package* 


SL75B 


£2850 


£985 


SL95B 




H.T.70 £1565 


401 


£27 45 


H.T. 70 Package 


GOLDFIHO 




££0 25 


UL69/2 




THOREHS 


GLS9P/2 


£2895 




GL75 




TD125AB £94 25 


GL75P 


£3850 


TX*H £870 


L1D69/7J 


£375 


TD130A1I £34 60 


099 


£1995 


TD160ABH £40 25 


PIONEER 




TX11 £8-77 


PL12AC 


£3650 


t Mono • 31 


ereo Cartridge 


All other mode 


s less Cartridge 


Cirriage !>"]/ ■■ 


tra any model 





TELETON SAO-206 
STEREO AMPLIFIER 




el. 

II + 6 waits rnih. Inputs lor mag. xtal, anx 
tape. Volume, baas, treble, sliding balance, 
scratch filler and loudness controls. List 
£32.50 OUR PRICE £17-50 Carr. 37p. 



TELETON SPECIAL OFFER I 




HOMER INTERCOMS 



2 Station £2.97, P. 4 P. 15p. 

3 Station £5.25. P. & P. 15p. 

4 Btatlon £8.82, P. * P. 17p. 



Ideal lor home, 
office, stores, fac- 
tories, etc. Supplied 
complete with bat- 
teries, cable and 
free instructions. 




RECORD DECK 
PACKAGES 
Decks supplied 

ready wired in 
plinth and rnvcr 
fitted with cart- 
ridge. Garrard 
2026 T/C with Sonotone 9TAT 

Garrard 9P2M1I Qoldrmg G800 

(larrar.l A P78 Goldrlng G800 

B8R MPOO Audio Technics AT.55 . . 
Cililrinc (1LB9/2 Goldring O800 . . 

Goldrlng OL75 Goldring G800 

Goldrlng GL75 C.oldring G8O0E. . . . 
Carriage 50p extra any model. 

_ SINCLAIR EQUIPMENT 



CR10T AM/FM STEREO TUBER AMPLI- 
FIER WITH MATCHTKG PAIR OF 
SPEAKER SYSTEMS. Output 4 watts per 
channel. Excellent reception. AFC, built-in 
MPX. Cer/XTAL Input. Total List £50 25. 
OUR PRICE £22 75. Carr. B2}p. 
Also available with Garrard 2025T/C Record 
Changer. Plinth, cover and stereo cartridge. 
Readv wire.) £38-50. Carr. £100. 



p ™i<%Jk*tt!£2L£ 



*##• 



lifti 




Z30 amplifier, stereo 00 pre-amp, FZD 
power supply. £18 75 Carr. 37,p. Or with 
PZB power supply £18-86 Carr. 37Jp. 2 x Z60 
amplifier, slereo 80 pre-amp, PZ8 power 
supply. £2025. Carr. 37,p. 
Transformer for PZ8. £2 971 extra. 
Add to any of the above £4-871 for active 
filter unit ami £13-90 tor pair of Q16 speakers. 
Project 60 KM Tuner £20-25. Carr. 371 p. 
All other Sinclair products in stock. 
2000 Amp £88 75 Carr. 37Jp.; 3000 Amp 
£31.50 Carr. 37Jp.: Neoteric Amp £43 95 

Carr. 37Jp 1C10/IC12 £2-50 
SEW PRO JECT 805 — £20 87. Carr. 3 7p. 
• TRANSISTORISED FM TUNER 

6 TRANSISTOR 
HIGH QUALITY 
TUNER, SIZE 
ONLY 6x4x2}ln. 
3 I.E. stages. 
Double tuned dis- 
criminator. Ample 
output, to feed most 
amplifiers. Operates on !> V battery. Coverage 
88-l08Mc>. Kcady built ready for use. Fan- 
tastic value for money. £8-37J. P. & P. 12|p. 
Stereo rmiltjplex_ada piora £4 -971- 

LATEST CATALOGUE 

Our new 6th edition gives full details of a 
comprehensive range of HI-FI EQUIP- 
MENT, COMPONENTS, TEST EQUIP- 
MENT anil COMMUNICATIONS EQUIP- 
MENT. FREE DISCOUNT COUPONS 
V A LI' E 50p 272 pages, fully illustrated and 
detailing thousands of bargains. 



SEND 
NOW! 

• 
STILL 
ONLY 

37ip 

p&P 

10p 



LAFAYETTE LA. 324 STEREO 

AMPLIFIER 
12 5 + 12.6 
watt R.M.8. 
Mag/Cer/Tuner 
/Tape Inputs. 
Excellent per- 
formance. 
Compares with 
amplifiers op 
to £40. 

OUR PRICE £84, Carr. 37}p. 




TAPE CASSETTES 

Top quality In plastic library boxes. 
CM «0 mta 87ip, 3 for £1-05 
CII0 90 min 80p, 3 for £1-66 
C120 120 min 87,p, 3 for £1-80 
Cassette Head Cleaner 56p. Pott Extra 



TE-40 HIGH SENSITIVITY 
A.C. VOLTMETER 

10 meg. input 10 ranges: 
01/003. -l'-3/l/3/l0/30/100/ 
300V. R.M.S. 4cps.-l-2 Mc/s. 
Decibel) -40 to -50.111. 
Bupplied brand new complete 
with leads and Instructions. 
Operation 230V. A.C. £17 60. 
Carr. 25p. 





TMK MODEL 117 F.E.T. ELECTROHIC 
VOLTMETER 
Battery operated, 
U meg Input, 26 
ranges. Large 41* 
mirror scale. Size 
5,- x 41- x 28". 
DC VOLTS 3- 
1200V. AC VOLTS 
3 - 300V RMS. 8.0 - 
800V P-P. DC CUR- 
RENT .12 - 12MA. 
2C00M ohm. Decibels 
/Instruc- 




Reslstance up 

- 20 to + 51 db Complete with I 

lions. £17.50, P. 4 P. 20p. 





EMI LOUDSPEAKER8 
Model 350. 13" x 8* with 
single tweeter/crossover. 
20-20,000 Hi. 15 watt 
RMS. Available 8 or IS 
ohms. £7-50 each. P. A 
P. 37p. 

Model 450. 13" x 8* with 
twin tweeters/crossover. 
55-13.000 Hx. 8 watt 
RMS. Available « or 15 
ohms. £3 50 each. P. 4 
P. 25p 



PRS-2 PHOTO ELECTRIC RELAY 

8Y9TEM 
Inexpensive warning 
or counting system 
consisting of an enclter 
and relay unit. Relay 
unit has variable sen- 
sitivity control and 
switch for Intermittent alarm operation. 
Knciter unit has removable infra red filler 
and A.C. outlet socket to operate bells, 
counters, etc. 240V AC. Complete with 
cables an.. Instructions. £8.97, P. * P. 25p. 

ac~, 





TE 1018 DE-LUXE 
MONO HIGH IMPE- 
DANCE HEADSET 
Sensitive, soft earpads, 
adjustable headband. 
Magnetic, impedance 
2.li(i0 ohms. 
£1 9 7. P. * P. 15p. 





MP7 MIXER PREAMPLIFIER 
5 microphone In- 
puts each with 
individual gain 
controls enabling 
complete mixing 
facilities. Battery operated. 91* X 5* X 3". 
Inputs Mies: 3 x SniV 50K ; 2 x 3m V f.00 ohm. 
Phono meg. 4m V 50K. Phono ceramic 
IOOiiiV 1 meg. Output 250mV 100K. 

£8.97. P. * P. 20p. 
KOSIDEN DH-02S STEREO HEADPHONES 
Wonderful value 

and excellent per- 
formance combined. 
Adjustable head- 
band. 8 ohm Im- 
pedance. 20-12.000 
cps. Complete with 
lead and stereo Jack 
plug. ONLY (2-371. 
P. *. P. 12}p. 



UR-1A SOLID STATE COMMUNICATION 

RECEIVER 

4 Bands covering 550kc/a-30me/s. FET, 

8 Meter, Variable BFO for 8KB. Built-in 

Speaker, Bandspread, Sensitivity Control. 

220/240v. A.C. or 12v. D.C. 12|" x 41* X 7*. 

Brand new with instructions. £25. Carr. »*|p. 




ONR-30 RECEIVEB 

4 Bands covering 530kc *-30m. -.'-. B.F.O. 
Built-in Speaker 220;240v. A.C. Brand new 
with instructions. £15 76. Carr. 37, p. 




1021 STEREO 
USTEXMO 
STATION 

For balancing and 
gain selection of 
loudspeakers with 
additional facility 
for stereo headphone 
switching. 2 gain 
controls, speaker on-off slide switch, stereo 
headphone sockets. 6' x 4* x 21*. £2-26, 
P. ft P. 15n. 




SH628 STEREO HEAD- 
SET 

Outstanding value. Soft 
earpads. adjustable bead 
band. 8-16 ohms. 20- 
•20.000Hz. Complete with 
cable and stereo jack 
Plug. £1-87. P.* P.15P- 



I.AFAYETTE HA-600 SOLID STATE 
RECEIVER 

— General coverage 
•a-f-a-*-f*****a-****j**-| i50-4noke/«, M" 

— ™ kc/s-30mc/». FET 

front end. 9 meeh. 
filters, product 
detector, varl.ibla 
B.F.O., nolae llml- 
ter. 8. Meter, Bandspread. RF Cain. IV * 
01" x 81*. 18 lbs. 220/240v. A.C. or 12v. D.C 
Brand new with instructions. £45. Carr. OOp. 




TO-2 PORTABLE OSCILLOSCOPE 

A general purpose low 
cost economy oscilloscope 
for everyday use. Y amp. f ~A 
Handwidth2CFS-lMHZ. 
Input Imp. 2 meg Q 25 
P.K. Illuminated scale. 
2ln. tube. 115 x 180 x 
230mm. Weight 81b. 
220/240 V a.c. Supplied 
brand new with hand- 
book. £22.50. Carr. 50p. 



SPECIAL 
PURCHASE 

Brand new 18" 100 watt 
speakers. Made by Celestion 
or Fane. IS* 100 watt rms. 
33 cps bass resonance. 
Limited itock only. 

Each 
Carr. 30p 





£13.95 




TE-18A TranalaloriaH 
Signal Generator. Sranges 
400kHx— 30mHx. An 
inexpensive Instrument 
for the handyman. 
Operates on 9v battery. 
Wide easy to read scale. 
800kHz modulation. 
51 x SI x 3lln. 
Complete wRh Instruc- 
tions and leads. (7-971. T. * P. 20p- 

RUSSIAN C1-16 DOUBLE 
BEAM OSCILLOSCOPES 

5 MHz Pass Band. Separate Yl, V2 ampli- 
fiers. Calibrated triggered sweep from -2 sec 
to 100 mill! sec/cm. 

Supplied complete with all accessories and 
instructions £87. Carr. paid. 



... ii.-. i. ..,....., — «..•(.... W(...ll.,trc <vTiiti...1.1»il \i\ vllrenus ^THC Sa £"nTi 



High quality ceramic construction. Windings embedded In vitreous 
enamel. Heavy duty brush wiper. Continuous rating Wide range 
ex-stock. Single hole fixing, jin. dta. shafts. Bulk quantities available. 
85 WATT. 10i25/50/100;25d;300; 1 000/ 1500 . 2S0O or 3000 ohms. 72ip. P. 4 P. 7] p. 
50 WATT. 10/25/00/100/250/500) 1 000/2500 or 5000 ohms. £105 P. 4 P. 71p. 
100 WATT. 1/6/10/25/50/100 250/500/1000 or 2500 ohms. £1-871 P. A P. 71p. 



230 VOLT A.C. 50 
CYCLES 

RELAYS 

Brand new. 3 seta of 
changeover contact* at 
5 amp rating. 50p each. 
P. A P. lOp (100 lots (40) 
Quantities available. 



"YAMABISHI" VARIABLE VOLTAGE TRANSFORMERS 

Excellent Quality . Low price . Immediate delivery 



»'•*>»■, ill's 



«# 



S-280 General 

Purpose Bench 

Mounting 

1 Amp £7 00 
2.5 Amp 

5 Amp 

8 Amp 
10 Amp 
12 Amp 
20 Amp 



£8 05 
£1175 
£1590 
£22 50 

£23 80 
£4900 




WM 



27 TOTTENHAM CT. RD. LONDON, W.I 
3 LISLE STREET, LONDON, W.C.2 
34 LISLE STREET, LONDON. W.C.2 
311 EDGWARE ROAD, LONDON. W. 2 



Tel: 01-636 3715 
Tel: 01-437 8204 
Tel: 01-437 9155 
Tel: 01-262 0387 



OPEN 9-6 MONDAY TO SATURDAY 



S-280B Panel Mouatinr 
1 Amp (7 00 

2.5 Amp It 06 

Please add postage 

ALL MODELS 

INPUT 2.10 VOLTS. 

50'60 CYCLES. 

OUTPUT VARIABLE 

0-260 VOLTS. 

Special discounts for quantity 



)LTD 



All Mail Orders to ■ 

11-12. Paddington Gre 

London W. 2 

Tel: 01-262 6562 

(Trade supplied) 



»9 



/ 



SUPERSCOtlPS 



RADIOS 

TAPES 

Hl-W 





rape 

Recorders 

Ferguson3245 

3247 

.. 3248 

.. 3258 

Philip* 4303 

4307 

4308 



ust 
Price 

£36-00 
£47-95 
£53-75 
£7200 
£4200 
£49-50 
£60-50 



P.S.P. 
Price 
£31 M 
£41-50 
£45-85 
£13-25 
£37-50 
£43-50 
£53-50 



(Ste 



FAMOUS TELETON— AM/FM 

Stereo Tuner Amplifier RSOOO 
Supplied complete with 2 ipssker ■ . 
Total 12 watt* RMS. Specification: 
MPX Beacon, AFC, Connections for 
Tape Recorder, Stereo Headphone 
Socket, etc. Mfgi. Rec. Price £63-50. 
P.S.P. FANTASTIC OFFER 

only £39.95 

Plus GARRARD DECK 202S. Fitted 
In Famous "Thorpe Grenvllle' Plinth 
A Cover with patented moulded motor 
board. Fitted with superb Sonotone 
BTAHCO cartridge. P.S.P. offer 
ONLY IF YOU BUY THE ABOVE 



Lateet release, baautlfully styled In 
walnut case, 6 + 6 watts r.m.a. 
Switched Inputs for magnetic Xtal, 
aux. Tap*. Incorporates volume, bass, 
treble and, alide balance control, 
scratch filter and loudness control. 
Rec. £3280. /IO.OC 
Our uric* » ■ * * 3 

Suggested Systam. 
SAO 206 Amplifier, SP25 III Plinth 
and Cover, G800 cartridge, pair large 
3- way apeaker system. 

Our price £59-95 

Would normally cost £85 complet*. 
Alio available with EM1 13 x 8 speaker 
system £M*5. 



itereo) 
Bush Cassette 

TR60 
Teleton TC 

110 Mains/ 

Bart. 
Teleton TRC130 

Mains/Baft. 
Also available full range 
Tape Recorders at 
discounts. 



Magnetic 
Cartridges 
Goldrlng G800 
Goldrlng 
G800H 
Shure MS5E 
Shure M 44-7 



Post and packing 20p. 
Superb Thorp* Gren- 
vllle plinths. 
Tinted perspex covers 
Incorporating patented 
moulded motor board— 
PSPPrlc*£4-5«PA P 
35p. 



£9500 £83 85 
£29-40 £24 85 



£27-75 £22 00 

£41-75 £31 5* 

o' Grundlg 
attractive 




Available at special price*. Linton's, 
Denton's, Wartedale speakers. Gold- 
ring GL69P & 6775P decks: Lesk, 
Delta 30 A 70 Rogers Ravensbrook, 
Ravensborne amplifiers, Sinclair 3,000 
amp A The Fidelity U1A/UA2 

Plus a wide rang* of itereo unit*. 

List P.S.P. 

price Price 

HMV 2452 Stereo £65-65 £57 85 

RH92 Philips 

System £12500 £110 M 

(Choice of speakers available, price* 
on appllcatlona). 

KB Audio 

Stereo 2010 £103-40 £82 50 
Ultra 6028 Group 

3 stereo £59-75 £51 M 

Ferguson unit 

sudlo £84-60 £74-24 

Ultra 6406 £77-00 £67-28 

Ferguson 3450 

Stereo £72-00 £63-50 

PERSONAL SHOPPERS 
PLAN LTD. 

The Centre 

36-SB West Green Road, Tottenham, 

N.1S Tel. No. 01-400 8633 

All orders C.W.O. Special Securlcor 
fast delivery £3. 



YOUR CAREER in 

RADIO & 
ELECTRONICS ? 

Big opportunities and big money await the qualified man 
in every field of Electronics today— both in the U.K. and 
throughout the world. We offer the finest home study 
training for all subjects in radio, television, etc., especially 
for the CITY & GUILDS EXAMS (Technicians' Certifi- 
cates); the Grad. Brit. I.E.R. Exam.: the RADIO 
AMATEUR'S LICENCE; P.M.G. Certificates; the 
R.T.E.B. Servicing Certificates; etc. Also courses in Tele- 
vision; Transistors; Radar; Computers; Servo-mech- 
anisms; Mathematics and Practical Transistor Radio course 
with equipment. We have OVER 20 YEARS' experience 
in teaching radio subjects and an unbroken record of 
exam, successes. We are the only privately run British 
home study College specialising in electronics subjects only. 
Fullest details will be gladly sent without any obligation. 



To: British National Radio School. Reading, Berks. 

Please send FREE BROCHURE to 



ADDRESS . 



. Cap*. 
Please 



12/71 



BRITISH NATIONAL RADIO SCHOOL 



THE LATEST AND 
THE GREATEST 
TO DATE... 

PRACTICAL 
MOTORIST 
ANNUAL 1972 

128-page guide to car maintenance, A to Z of 
motoring terms,, fault finding, overhaul, im- 
provements, renovation/preservation, electrics, 
leisure, accessories, data sheets and handy 
hints in an attractive four-colour cover! 
Be sure to get your copy as soon as possible. 
ON SALE NOW, PRICE 25p 



750 



ELECTRONIC VALVES 



OA2 

OA3 

OB2 

OB3 

OCS 

OD3 

1B3GT 

1CP31 

1L4 

1R4 

1R6 

134 

185 

1T4 

1U4 

1U6 

1V2 

1X2B 

2D21 

3A4 

3B28 

3BP1 

3Q4 

394 

3V4 

5R4GY 

6Y4G 

6U4GB 

6V4G 

8Y3GT 

6Z3 

6Z4G 

6/30L2 

6AB4 

6AF4A 

6AG7 

6AH6 

6AJ8 

6AK5 

6AK6 

6AL3 

6AL8 

6AM6 

6AM6 

6AQ5 

6AQ6 

6AR8 

6AR6 

6AR11 

6A85 

8AB7G 

6AT8 

6AD6 

6AV6 

6AW8A 

6BA6 

8BE6 

6BF5 

6BF8 

6BH5 

6BJ8 

8BK7A 

6BN5 

6BN6 

8BQ5 

6BR8 

6BS7 

8BW6 

6BW7 

6BX6 

8BZ6 

6C4 

8C5GT 

6CB6 

6CD6GA 

8CG7 

6CH6 

BCL6 

6CW4 

6CY5 

6CY7 

6D3 

6DC8 

6DK6 

6DQ6B 

6D84 

6EA8 

6EH7 

6EJ7 

8EW8 

6F1 

6F5 

6F6G 

6F11 

6F13 

6F14 

6F15 

6F18 

6F23 

6F24 

6F26 

6F26 

6F28 

6J4 

8J5GT 

6J7 

8K80T 

6K7 

6K8G 

6K26 

6L6GT 

6L7 

ST. 18 

6LD20 

6X7GT 

BP1 

6P25 

6P28 

6Q7 

68A7 

68G7 

68K7 



038 
0-45 
0-35 
080 
0-38 
085 
038 
800 
020 
035 
035 
027 
025 
25 
0-27 
060 
045 
040 
0-85 
085 
215 
275 
40 
085 
045 
0-80 
083 
042 
042 
0-32 
050 
040 
0-76 
085 
060 
0-40 
050 
030 
080 
057 
048 
020 
082 
083 
85 
056 
085 
040 
1-26 
035 
080 
080 
025 
030 
055 
025 
030 
080 
050 
045 
0-45 
055 
043 
040 
025 
085 
1-80 
055 
070 
025 
085 
038 
0-40 
080 
116 
0-50 
0-55 
050 
083 
043 
086 
045 
076 
48 
068 
075 
068 
080 
085 
085 
070 
050 
080 
038 
088 
085 
0-65 
045 
080 
0-76 
0-75 
035 
060 
050 
080 
045 
066 
085 
035 
0-75 
045 
040 
045 
040 
040 
060 
125 
085 
0-40 
40 
035 
035 



7sT7G^!r?r 

68N7GT 0-85 

68Q7 040 

68R7 

6T8 

6U4GT 060 

6U8A 0-40 

6V6GT 0-88 

6X4 

6X6GT 085 

6X 8 0-55 



040 
36 



6Y8G 

7Y4 

9BWH 

10C2 

10D1 

10D2 

10F1 

10F9 

10F1S 

10L1 



065 
080 
050 
050 
050 
40 
090 
050 
45 
0-45 



DY87 

DY802 

E88CC 

E180F 

E810F 

EABC80 35 

EAF42 55 

EBC33 

EBC41 

EBC81 

EBF80 0-40 

EBF83 0-40 

EBF8B 

EC63 



OT55 
050 
0-65 
096 
290 



050 
0-55 
080 



PCC88 FM 
PCC89 0-60 
PCC189 055 
PCC805 0-86 
PCC806 080 
PCF80 0-80 
PCF82 
PCF84 
PCF88 
PCF87 



KC8B 
EC88 
EC90 

Kl-'.l! 
E092 
EC93 



0-80 
50 
0-60 
060 
088 
050 
0-85 
050 



1 OLD II 80 
10P13 0-55 



10P14 

12AB5 

12 ACS 

12AL5 

12AQ5 

12AT8 

12AT7 

12AU6 

12AU7 

12AV6 

12AV7 

12AX7 

12AY7 

12B44A 0-65 

12BAB 085 

I2BA7 

12BE6 

12BH7 

12BY7 

12K5 

12K7GT 0-85 

12Q7G 030 



1-10 
0-60 
0-40 
0-46 
43 
030 
033 
030 
080 
088 
050 
030 
0-70 



085 
86 
040 
055 
055 



EC8010 2-25 
ECC40 0-60 



ECC81 
ECC82 
ECC83 
ECC84 
ECC86 
ECC88 
ECG89 
ECC91 



0-88 
080 
030 
080 
0-40 
040 
050 
020 



036 
050 
060 
085 



PCF801 50 
PCF802 0-60 
PCF805 0-75 
PCF806 0-70 
PCF808 0-76 
PCH200 0-70 
PCLS1 050 
PCL82 
PCL83 
PCL84 
PCL85 
PCL88 
PCL88 



086 
065 
046 
040 
045 
090 



128R7 

1487- 

20D1 

20L1 

20P1 

20P4 

20P5 

25C5 



035 
080 
045 
110 
050 
110 
1-20 
050 



ECC189 0-60 
ECF60 085 
ECF82 0-35 
ECF86 85 
ECF804 1-60 
ECH42 070 
ECH81 0-80 
ECH83 040 
ECH84 045 
ECL80 
ECL81 
ECL82 
ECL83 
ECL34 
ECL85 
ECL8B 
ECLL800 

150 
EFS7A 
EF39 



PCL800 0-88 

PCL801 0-70 

PDBOO I'M 

PF86 0-M 

PF818 085 

PFL200 0-70 

PL33 085 



40 
045 
035 
065 
0-66 
0-55 
40 



25L6GT 45 

25Z4G 030 

25Z6GT 065 

30AS 0-45 
30AE3 
SOC1 



30C15 

30C17 

30C18 

30F5 

30FL1 



0-40 
080 
080 
085 
075 
086 
070 



30FL12 098 
30FL14 076 
30L1 040 



30L15 
30L17 
80P12 
30P19 
30PLI 



086 
080 
80 
80 
0-70 



SO PL 13 93 
30PL14 90 
35A3 055 



35 A 5 
35B5 
35CS 
35D5 



075 
085 
040 
0-70 



35L6GT 0-50 

35W4 0-80 

35Z3 60 

35Z4G 80 

35Z50T 0-40 

BOAS 070 

50B5 0-45 

S0C5 0-40 

S0CD6G 1-65 

B0L6GT 0-50 

85A2 040 



; EF40 

EF41 

EF42 

EF80 

i EP83 

j EF85 

! EF8S 

I EF89 

1 F.F91 

I EF92 

EF95 

I EF97 

1 EP98 

i EF183 

I EF184 

EF800 

' EP804 

EK90 

EL33 

! EL34 

EL36 

EL87 

F.I. 41 

EL42 

EL81 

EL83 

EL84 

EL85 

F.l.Sfi 

EL90 

EL95 

EL803 

EL821 

EL822 



90AQ 

OOAV 

90C1 

90CV 

807 

813 

866A 

B642 

6080 

6148 

6380 

6870 

6939 

7199 

7380 

7886 

7895 

9002 

9003 

AZ1 

AZ31 

C1U,1 

CBL31 

CY31 



240 
250 
060 
1 25 
060 
375 
075 
065 
1-50 
1-50 
125 
260 
215 
0-75 
1 SO 
125 
1-25 
0-85 
050 
048 
055 
0-80 
090 
085 



080 
040 
050 
65 
0-70 
025 
055 
035 
80 
028 
033 
040 
080 
065 
065 
030 
0-86 
100 
125 
080 
125 
060 
050 
126 
0-56 
068 
066 
0-42 
025 
043 
0-40 
085 
086 
1.00 
055 
090 



' PL38 


056 


PL81 


060 


PL82 


046 


PL83 


045 


PL84 


040 


PL302 


080 


1 PL604 


OHO 


1 PL508 


090 


■ PL509 


130 


1 PL801 


080 


PM84 


0-M 


PY31 


ORO 


PY83 


068 


PY80 


086 


PY81 


U-MI 


PY82 


080 


i PY83 


088 


I PY88 


040 


PY600 


1 00 


1 PY800 


OH 


1 PY801 


50 


PZ30 


085 


1 QQV2-< 


216 


' QQV03 


10 




1-26 


, QQV03- 


20A 




625 


QQV06-4A 




650 


| TT21 


266 


TT22 


280 


1 U18/20 


075 


| U25 


075 



U28 

U31 

U37 

U52 

TJ78 

U78 

U191 

l.'201 

U281 

U282 

L'301 

I 1113 

L'404 

U801 



075 
45 
160 
038 
080 
010 
076 
086 
040 
040 
040 
0-50 
040 
100 



ELL80 075 
EM34 090 



EM71 

EM80 

EM81 

EMS4 

EM85 

EM87 

F,N91 

EY61 

EY80 

EY81 

BY83 

EY8B 

EY87 

EY8S 

EZ40 

EZ41 

EZ80 

EZ81 

OYD01 

GZ80 

OZ31 
C1Z32 
GZ33 
OZ34 



075 
040 
060 
085 
I 00 
055 
085 
040 
046 
040 
055 
040 
043 
048 
46 
045 
025 
028 
080 
040 
0-83 
048 
070 
080 



LTABC80 86 
i UAF41 060 
I UAF42 
: UBC41 

UBC81 
! CBF80 40 
i TJBF89 88 

i HI l 

UBL21 
! UC92 

UCC85 
' UCF80 55 

UCH21 60 
i UCH42 0-70 
1 UCH43 75 
I UCH81 35 

UCL81 

UCL82 

UCL83 
I UF41 



055 
0-50 
0-40 



060 
060 
086 

040 



DAF96 0-42 
DF9B 0-42 



DK40 
DK92 
DK96 
BL96 



055 
050 
042 
042 



HABC80 0-40 
iiK'.hi 0-85 
KTBB 206 
KT88 2-00 
N78 1 45 

PABC80 40 
PC86 060 



UF42 

UF43 

1TF80 

UF85 

TJF89 

UL41 

UL84 

UM84 

TJY1N 

UY11 

UY41 

TJY82 

UY88 

W729 

Z7B9 

Z80.-U' 



080 
085 
060 
0-80 
060 
060 
35 
040 
035 
85 
0-80 
0-20 
050 
066 
045 
050 
080 
0-60 
1-85 
090 



PC88 

PC97 

PC900 

PCC84 

PCC85 



60 
050 
48 
40 
040 



STEPHENS 



ELECTRONICS 
P.O. BOX 26 
AYLESBURY, BUCKS. 



SEND S.A.E. FOR LISTS 

GUARANTEE:— 

TERMS CASH WITH ORDER ONLY. 

POST AND PACKING PAYABLE 

ON ORDERS UP TO £6, AFTER 

THAT FREE, EXCEPT C.R.T's 



Satifaction or money refunded. 

ALL ITEMS ADVERTISED IN LAST 

MONTH'S ISSUE ALWAYS IN 

STOCK FOR SAME DAY 

DISPATCH 



SEMICONDUCTORS BRAND NEW 
MANUFACTURERS MARKINGS NO REMARKED 



9H388A 

2X614 

2N697 

2NB98 

2N706 

2X706A 

2X930 

2N1132 

2N1303 

2X1308 

2N1308 

2N1307 

2X1711 

2X2147 

2N21B0 

2X2614 

2X2846 

2X2905 

2X2926 

Green 

Yellow 

Orange 

2X3053 

2X3055 

2X3391 

2X3392 



62,p 
80p 
20p 
25p 
12,P 
12.P 
27jp 
82.P 
17,p 
251p 
26p 
25p 
25p 
72.P 
57,p 
80p 
57Jp 
40p 

14p 
12»p 
18»p 
27,p 
76p 
20p 
20p 



20p 

85 

80p 

87p 



2N3702 17JP 
2N3704 22JP 
2N3708 20p 
2N3711 " 
2N3819 
2 N 3826 
2N3908 
2N3914 P.A. 
R.C.A. 

40283 P.A. 
40398 P.A. 
40458 P.A. 
2N40B1 2£,p 
2N4062 22, p 
2X4286 17|p 
2N4291 17»p 
AC107 80p 
AC117 
AC126 
AC 127 
AC128 
AC1B4 
AC176 
AC 187 



60p 
20p 
B5p 
80p 

22,P 
25p 

62»p 



AC188 87»p 
ACY17 27Jp 



ACY18 

ACY19 

ACY20 

ACY21 

A0Y39 

ACY28 

ACY40 

ACY41 

ACY44 

AD140 

AD142 

A 1)1-19 57 1 p 

AD160 62* p 

AD161 87JP 

AD162 37,p 

AF102 58p 

AF106 42, p 

AF114 25p 



25p 
25p 
26p 
26p 
20p 
20p 
20p 
26p 
40p 
40p 
58p 



AF11B 
AF116 
AF117 
AK118 
AF119 
AF124 
AF126 
AF126 



80p 
26p 

25p 
60p 

eop 

22,p 
20p 
20p 



DIODES ft RECTIFIERS 







BZY88 


OA91 


7»P 


AA119 




(Series) 82, p 


OA202 


lOp 


BA102 


22iP 


OA5 12|p 


BA144 


12,P 






OA47 7»p 


BA145 






12iP 


OA70 7»p 


BA148 


28p 




22,p 


OA79 9p 


BA1S5 




BY12B 


20p 


OA81 7,p 


BA166 




BY127 


22»P 


OA90 7«p 







AF127 17ip 

AF139 87tp 

AF178 45p 

AF179 45p 

AF180 52ip 

AF181 42tp 

AF186 BUip 

AF2S9 42ip 

A8Y28 28p 

BO107 16p 

BC108 15p 

BC109 15p 

BC113 27»p 

BC114 37, p 

BC116 32' p 

BC116 62iP 

BC116A 37, p 

BC117 38p 

BCU8 82,p 

BC134 67Jp 



BC136 
BC138 
BC137 
BC138 
BC142 
BC143 



P.A. 
P.A. 
P.A. 
P.A. 
80p 
P.A. 



BC147 17tp 
BC148 16p 
BC149 17Jp 
BC182 17tp 
BC1B7 2 Op 
BC168 17, p 
BC169B 14p 
BC169C 15p 
BC171 17ip 
BC176 27ip 
BC183 22}p 



BC184 

BC187 

BC213L 

BCY32 

BCY58 

BCY70 

BD11S 

BD121 

BD123 

BD124 

BD131 

BD1S2 

BF115 

BF117 

BF160 

BF162 

BF163 

BF167 

BF173 

BF178 

BF179 

BF180 

BF181 

BF184 

BF194 

BF19B 

BF196 

BF197 

BF198 

BF200 

BF224 

BK225 

BF257 

BFX84 

BFY19 

BFY50 

BFY51 



DEVICES 

22}p | BFYB2 



B8X21 

OC25 

OC26 

OC28 

OC29 

OC35 

OC36 

OC42 

OC44 

OC45 

OC46 

OC70 

OC71 

OC72 

OC74 

OC7S 

OC76 

OC77 

OC78 

OC81 

OCS1D 

DC83 

OC84 

OC139 

OC140 

OC170 

OC171 

OC200 

OC202 

OCP71 

P346A 

TI8 



28Jp 
26.P 
87,p 
22 ip 
20p 
78p 
65p 
824P 
62tp 
97ip 
97tp 
26p 
47ip 
P.A. 
P.A. 
35p 
26p 
S2,P 
86p 
72ip 
86p 
82,p 
26p 
22ip 
27iP 
42.P 
Slip 
42,p 
86iP 
80p 
80p 
47Jp 
30p 



22Jp P.A. Price on 

22,p I application 



221P 
87Jp 
50p 
82iP 
621p 
76p 
40p 
821P 
25p 
20p 
12*P 
ISP 
16p 
12,p 
12ip 
32iP 
22,p 
22,p 
27,p 
25p 
20p 
20p 
26p 
25p 
821p 
82iP 
SOp 
20p 
88iP 
47,p 
42iP 
25p 
40p 



CARTRIDGES 



/«. P. T. 
tack 

AC08 

OP79 Mp 

GP91— lBc 11-05 

OP91— 28c 1106 

GP91— 88c (TC8) . 11 06 

GP92 11 82 

GP93— 1 11-24 

GP94— 1 I1U 

GP94— 6 11-80 

GP9B 11-24 

OP96 11-67 

Aooa 104 1—10 1209 

B.8.E. 

X3M ..8/8 .. 1189 



X3H 

X6M 

X6H 

8XBM 

8X5H 

BXSM 

BXBH 

X4N 



8/8 
B/S 
8/8 
8/8 
8/8 
D/B 
D/8 

D/a 



rach 
1138 
£139 
£1 39 
1181 
11-81 
12 00 
12 00 
1136 



OOLDBIHQ 

8M 15-25 

G800 17-85 

C800E £15-00 

O800 Super E .. 11B-M 



RONETTE 
105 
106 
DC400 
DC4008C 
105 
106 
DC400 
DC4008C 

SOHOTOITE 
8TA 
9TS 
9TAHC 



8/8 
8/8 
8/8 
8/8 
D/8 
D/8 
D/8 
D/S 



D/8 
D/8 
D/9 



98p 
99p 

70p 
70p 
1118 
1112 
84p 
84* 



1125 
1179 
1178 



BEST QUALITY 

CAPACITORS 

WIMA DUROLIT 

Working 



WIMA TROPYFOL 



Capacilam 
1000 pF 
1600 pK 
2200 pF 
3300 pK 
4700 pF 
6800 pF 
001 fiF 
0-018 itV 
0022 pF 
0033 at 
0-047 uV 
0068 (jF 
1 uV 
018 n? 
0-22 ^F 
470 pF 
680 pF 
1000 pF 
1600 pF 
2200 pF 



Voltage 

630 

A30 

830 

630 

630 

630 

630 

630 

630 

630 

630 

630 

630 

630 

630 
1000 
1000 
1000 
1O00 
1000 



Capacitance 

47 pF 

68 pF 

100 pF 

ISO pF 

220 pF 

330 pF 

470 pF 

001 uV 

0016 jiF 

0022 /iF 

0033 »iF 

0047 uF 

0-068 uF 

01 uV 

0-22 uF 

1600 pF 

2200 pF 

3300 pF 

4700 pF 

6800 pF 

001 jiF 

0016 uV 



Working 
Voltage 

400 

400 

400 

400 

400 

400 

400 

400 

400 

400 

400 

400 

400 

400 

400 

630 

630 

630 

630 

630 

630 

630 



BJl 

m 

21p 

21p 
21 p 
i9j 
21p 
23p 
23p 
25p 
27p 
83p 
46p 
21p 
21p 
21p 
21p 
23p 
25p 
25p 



'Capacitance 
0022 tiF 
0033 uF 
0047 fiF 
1000 pF 
1500 pF 

'2200 pF 
3300 pF 
4700 pF 
6800 pF 
0-01 iif 
0-015 uF 



Working 
Voltage 

630 

630 

630 
1000 
1000 
1000 
1000 
1000 
1000 
1000 
1000 



27p 
811 

86» 
21P 
21f 
28p 
23p 
25p 
27p 
27p 
81p 



0022 uK 1000 86p pack of 6 

ADD 6p PER ITEM POST AND 

PACKING 



MAGNETIC RECORDING TAPES by a leading manufacturer 



POLYESTER 






Bpool Si/.c in. 


Standard Play 




600ft 




880ft 


M 


1200ft 


7 


Long Plajr 




210(t 




45011 





POLYESTER 



1200ft 
1800ft 
70p Double Play 
1200ft 
1800ft 
2400H 



60p 
68p 



27p 
43p 




EMPTY TAPE REELS 

3i» 7p 

4in 8p 

5in HP 

6|ln 18p 

7ln 18p 



CASSETTES 
Boied in Plastic Library Packs 

C60 53p 

C90 68p 

C120 .. 87p 

P. & P. 7p on all orders. 



751 



28watts, r.m.s. 40Hzto40kHz*3dB 




There are two stereo amplifiers — the RIOO for ceramic cartridges, 
the R 101 for magnetic and ceramic. Both incorporate FETs (FIELD EFFECT 
TRANSISTORS), just like top-priced units. FETs give you more of the 
signal you want, and almost none of the background hiss you don't. 
Both units have a jack socket to plug in headphones and there's a 
separate output for tape recorder. Filters (an unusual feature in this 
price range) and tone controls give a wide range of bass and treble 
adjustment which compensate for input deficiencies and domestic 
acoustic conditions. 



PRICES SYSTEM I 

Viscount III RIOI amplifier £2200 + 90p p&p 

2 x Duo Type II speakers, £l400 + £2 p&p 

Garrard SP25 Mk. Ill with MAG. 

cartridge plinth and cover £23-00+£l -50 

p&p 

Total £59 00 

Available complete for only £52 00 + £3 50 

p&p 

SYSTEM 2 

Viscount RIOI amplifier £22 00 + 90p p&p 

2 x Duo Type III speakers £3200+ £3 p&p 

Garrard SP25 Mk. Ill with MAG. 

cartridge, plinth and cover £23 • 00 -i- £ I -50 

p&p 

Total £77 00 

Available complete for £69 + £4 p&p 

SYSTEM 3 v 

Viscount III Amplifier RIOO \£l700 + 90p p&p 
2x Duo Type II speakers, pair £l400 + £2 p&p 
Garrard SP25 Mk. Ill with CER. diamond 
cartridge, plinth and cover £21 004-£l -50 

p&p 

Total £52-00 

Available complete for only £49 00 + £3 50 

p&p 



R+TV 



SPEAKERS Duo Type II 

Size approx 17" x I0j' x 6J". Drive unit 13" x 8" 
with parasitic tweeter. Max. power 10 watts. 3 
ohms. Simulated Teak cabinet. 

£14 pair £2 p&p. 

Duo Type III Size approx 23±" x Hi" x 9i". 
Drive unit I3i" x 8±" with H.F. speaker. Max. 
power 20 watts at 3 ohms. Freq. range 20Hz to 
20kHz. Teak veneer cabinet. £32 pair 4- £3 p&p. 



SPECIFICATION RICI 

14 watts per channel into 3 to 4 ohms. Total distortion 
@ I0W @ IkHi 01%. P.U.I (for ceramic cartridges) 
l50mV into 3 Meg. P.W.2 (for magnetic cartridges) 
4mV @ I kHz into 47 <. equalised within ± IdB 
R.I.A.A. Radio l50mV into 220K. (Sensitivities given 
at full power). Tape out facilities; headphone socket, 
power out 250mW pei* channel. Tone controls and 
filter characteristics. Bass: + l2dB to — l7dB @ 60Hz. 
Bass filter: 6dB per octane cut. Treble control: treble 
+ l2dB to -l2dB @ If.kHz. Treble filter: l2dB per 
octave. Signal to noise ratio: (all controls at max) 
RIOI— P.U.I and rac io— 65dB. P.U.2. -58dB. 
RIOO same as RIOI but P.U.2 (for crystal cartridges) 
450mV into 3 Meg. Cross talk better than — 35dB on 
all inputs. Overload characteristics better than 26dB on 
all inputs. Size approx 3j" x 9" x 3f". 



Radio and TV Components (Acton) Ltd. 21e High Street, Acton, London W3 6NG 
323 Edgware Road, London, W.2. Mail orders to Acton. Terms C.W.O. All enquiries S.A.E. 
Goods not despatched outside U.K. 



752 



SOUND 50 

50 WATT AMPLIFIER & SPEAKER SYSTEM 




The Sound Fifty valve amplifier and speakers are sturdily 

constructed with smart housings and thoroughly tested 

electronics. They are designed to last — to withstand the 

knocks and bumps of life on the road. Built for the small 

and medium sized gig, they are easy to handle and quick 

to set up and can be relied upon to come over with all 

the quality and power you need. 

Output Power: 45 watts R.M.S. (Sine wave drive). Frequency response: 

-3dB points 30Hz at 18KHz. Total distortion: less than 2% at rated 

output. Signal to noise ratio: better than 60dB. 

Speaker Impedance: 3, 8 or 15 ohms. Bass Control Range: ± 13dB at 

60Hz. Treble Control Range: ± 12dB at 10 KHz. Inputs: 4 inputs at 

5mV into 470K. Each pair of inputs controlled by separate volume 

control. 2 inputs at 200mV into 470K. 

To protect the output valves, the incorporated fail safe circuit will 

enable the amplifier to be used at half power. 

SPEAKERS! Size 20* x 20" x 10" incorporating 12' heavy duty 

25 watt high flux, quality loudspeaker with cast frame. Cabinets 

attractively finished in two tone colour scheme — Black and grey. 

COMPLETE SYSTEM 

Sound 50 amp and 2 speakers 



THE ELEGANT SEVEN Mk. Ill 




(350m W Output) 



7 transistor fully-tunable M.W.— L.W. superhet 
portable. Set of parts. Complete with all com- 
ponents, including ready etched and drilled 
printed circuit board — back printed for foolproof 
construction. 
MAINS POWER PACK KIT : 7Sp extra. 

Price £5.25 plus 50p. P. & P. 
Circuit 13p FREE WITH PARTS. 



THE DORSET (eoom w output) 




7-transistor fully tunable M.W.— L.W. super- 
het portable. Set of parts. The latest modulised 
and pre-alignment techniques make this simple 
to build. Sizes : 12 x 8 x 3in. 

Price £5.25 plus 50p P. & P. 

Circuit 13p FREE WITH PABT8 




£50 



or available separately. 



Plus 

£6 

P. &P. 

Amplifier £28.50 plus £1.50 P. & P. 
Speakers £12.50 each plus £2.25 P. & P. 



CONTINENTAL 
4 TRACK, 
3 SPEED 
TAPE DECK 

with high impedance heads 
R.C. 74 tape deck. Three 
speeds— 1\. H and 1} ips. 
4-track record/playback head. Plus 4-track erase head. Positive pressure 
pad system. Takes any tape spool up to and including 7". The R.C. 74 
is driven by a powerful 200/2SOV 50-cycle A.C. motor. A heavy, accur- 
ately balanced, flywheel brings wow and flutter levels down to approx. 
0.3% total at H and 7± ips. Fast rewind in both directions. 
Controls couldn't be simpler! Just five push buttons that interlock to 
cut out accidental tape damage. Efficient servo-action type braking. 
Easy drop-in tape loading. 

The R.C. 74 comes with an attractive moulded deck cover, which has 
positions for tone and volume controls. The unit is built into a rigid 
die-cast frame, and overall size of the whole unit is 12} xlltx 6 inches. 
Every single deck fully tested before dispatch. Spools not supplied. 
Price complete £15-00. Plus 75p P. & P. 




Provides a high standard of sound reproduction, with full 
mixing facilities. It's versatility makes it suitable for: 
Discotheque, P.A., Home Entertainment Applications, -tc. 

• Five Electronically Mixed Inputs 

• Three Individual Mixing Controls 

• Separate base and treble controls common to all five 
inputs 

• Mixer employing F.E.T. (Field Effect Transistor) 

• Solid State Circuitry • Attractive Styling 



£9.50 



plus P. & P. 60p. 



INPUTS:— 1. Crystal Mlc or Guitar flmV. 2. Moving coll Mic or Guitar 8mV. 

Inputs 3, 4 & 5 are suitable for a wide range of medium output equipment (Gram. 

Tuner. Monitor. Organ, etc.). All 250mV sensitivity. 

CONTROLS:— 3 Volume controls. Bass control range : 13db @ 60 Hz. Treble 

control range ± 12db @ 15KHz. Separate ON/OFF Switch. Neon Indicator. 

POWER OUTPUT:— 12 Watts R.M.S. Into 3 to 4 ohms speaker 

SrG N A L/NOISE:— Better than -60db on Inputs 3, 4 and 5 4. -50db on 1 A 2 

SUPPLY:— 220 - 250 AC Mains. SIZE:— 121" * 6" x 3J" 



ALL TRANSISTOR 

Beautifully designed to blend with the interiors of all cars. 
Permeability tuning and long wave loading coils ensure 
excellent tracking, sensitivity and selectivity on both wave 
bands. R.F. sensitivity at 1MHz is better than 8 micro volts. 
Power output into 3 ohm speaker is 3 watts. Pre-aligned 
I.F. module and tuner together with comprehensive instruc- 
tions guarantees success first time. 12 volts negative or 
positive earth. Size 7in x 2in x 4£in deep. 

SET OF PARTS 

£6.30 

plus P. & P. 50p. 

Circuit diagram 13p. Free with parts 
Speaker, baffle and fixing kit £1'ZS 
extra plus 25p. p. & p. Postage tree 
when ordered with parts. 

See previous page 
for address 



sO ^ COMP °A, f/V . 

R TV 



753 



Practical Wireless Classified Advertisements 

The pre-paid rate for classified advertisements is 8ip per word (minimum 12 words), box number 7-^p 
extra. Semi-displayed setting £6 per single column inch. All cheques, postal orders, etc., to be made 
payable to PRACTICAL WIRELESS and crossed "Lloyds Bank Ltd." Treasury notes should always 
be sent registered post. Advertisements, together with remittance, should be sent to the Classified Ad- 
vertisement Manager, PRACTICAL WIRELESS, IPC Magazines Ltd., Fleetway House, Farringdon 
Street, London, EC4A 4AD for insertion in the next available issue. 

Miscellaneous 



LIGHTWEIGHT 
TREASURE-PROBE 

Look for BURIED COINS, silver, gold 
and metal relics PROFESSIONALLY 
with the BOFFIN solid-state TREASURE- 
PROBE. An extremely EASY-TO-BUILD 
kit that REALLY DOES WORK I SIMPLE- 
TO-FOLLOW INSTRUCTIONS. It comae 
to your doorstep with maximum-copper 
PRINTED-CIRCUIT BOARD plus ALL 
ELECTRONIC COMPONENTS including 
search-coll and earphone. Think of the 
fun you'll have BEACHCOMBING with 
the sensitive TREASURE-PROBE, and 
the expectancy of hearing its LOUD 
BEEP' to tell you "YOU'RE ON TO 
SOMETHING" GET YOUR TREASURE- 
PROBE SEND £6-95 NOW! 

BOFFIN PROJECTS 

4. CUNLIFFE RD. 

STONELEIGH EWELL 

SURREY 
Designed by GERRY BROWN & JOHN 
SALMON and presented on TV 



TOP TRANSISTORS- 

Brand New and Individually Tested Tran- 
sistors supplied unmarked, but packed 
separately for {(identification and guaranteed 
to be within their correct specification or 
money refunded. All at 9p. each or 

Any IS transistors for only £1-90 
ACY22 BFY5I OC72 2N3702 

BCI08 BFY52 OC202 2N3703 

BCI09 BSY27 ZTX300 2N3705 

BCI68 OC45 2N706 2N3706 

BCI69 OC7I 2N2926 2N3708 

Money back guarantee, P. & P. I Op. 

j. M. KING (Q) 

17 Buckridfe, Portpool Lane, London, E.C.I 



SYNTHESISER 

MODULES 

Send SAE for details of voltage-l 
controlled modules for synthe-l 
siser construction to D.E.W.I 
Ltd.. 254 Ringwood Road, Fern- 
down, Dorset. 



JAPANESE LAFAYETTE short wave 
receiver covers worldwide short wave 
broadcast stations plus BBC medium 
wave. Modern "receiver size" slide 
rule dial. Brand new. Two only. £20 
each. Leaflet available. S.A.E. to 
Beestin, 334 Nine Mile Ride, Woking- 
ham, Berks. Tel. Eversley 3674 (even- 
ings). 



MARKEM ELECTRONIC AIDS 

SIGNAL INJECTORS iK/c output can be heard 
well above 40 M/Hz. £2-34 each. 

SIGNALTRACERS complete with earpiece: R.F- 
and A.F. Input at the flick of a switch. £3 00 
each, fully tested. 

Both units use P.P.3. battery (not supplied) 
Post free in U.K. C.W.O. only. 

KEMWORTHY TOOLS LIMITED 
LYON ROAD, 

MERTON.SW19 2RT 



JOHN SAYS..." 



RING MODULATOR by Dewtron is 
professional, transformerless. 5-transistor, 
has adjustable FI/F2 rejection. Module £7. 
Unit £8-90. WAA-WAA Pedal kit of all 
parts, incl. all mechanics & instr. Only 
£2-95. AUTO RHYTHM from Dewtron 
modules. Simple unit for waltz, foxtrot 
etc. costs under £20 in modules. SYNTHE- 
SISER MODULES and other miracles. 
Send I5p for illusc. list. 
D.E.W. Ltd., 254 Ringwood Road, 
Ferndown. Dorset. 



TAPE HEADS 

PIGK-UP 
CARTRIDGES 

SERVICE MANUALS for Pre 1958 
H.M.V. and E.M.I. MODELS. 
Radio and Record Player Manuals 
25p each. Television Manuals 
37» 2 P each. Send C.W.O. stating 
model required. 

Send stamp for comprehensive 
lists of transformers, condensers, 
resistors, cartridges and tape 
heads. 

R.D.I. LTD., 

Chilton Works, Garden Road, 

Richmond, Surrey. 



: HEARWtOTS AJMfri 

TALK THEIR 



VHF AIRCRAFT 
BAND CONVERTER! 



Today'* skies are full uf twitting 
crosstalk as aircraft from giant Jets 
to small private planes jo- tie to take 
off and land. Now yon can eavesdrop 
on their tense conversations with 
this remarkable ready-to-ase, folly- 
trensist. b»tt. converter. Place 
it 1' away from any etd. 
medium-wave radio (even tiny 
portable I) for crystal-clear 
reception on aircraft communi- 
cations. 
Money bark guarantee. 




BU 



1 



DEPT. P.W.4. 
372 EDGWABE BOAD. 
LOHDOU, Wi. 
01-723 0094 



THE NEW 

ELECTRONIC MUSIC FOR YOU 

Then how about making yourself an elec- 
tric organ? Constructional data available 
full circuits, drawings and notes! It has 
5 octaves. 12 manuuLs and pedals with 24 
stops -uses 41 valves. With its variable 
attack .you curr play Classics and Swing. 
Write NOW for tree leaflet and further 
details to C. & S.. 20 Maude Street. 
Darlington. Durham. Send 2Jp stamp. 



IRISH READERS. Eagle products avail- 
able, send lOp in stamps for latest 
illustrated catalogue to Toner Elec- 
tronics, Lismore Park, Waterford. 



DO-IT-YOURSELF .... we stuck * Urge range 
o( audi., ami electronic component » at very com- 
petitive prices, e.g.: chassis speakers cross-over 
networks, hi-fi speaker kits (Wharferialr & Peerless). 
BAF sound absorbent, speaker grille fabrics, 
inductors, resistors, electrolytic* (reversible and 
polarised), transistors, etc. Senil for FREE list 
C2 x 3p stamps for fabric saiiiplesl. Mail order 
ONLY, No callers please. 

l , HI-H-CT3o.p..pwt, 



a, PRINCES SQUARE, 
HARROGATE, YORKB. 



BUILD IT in a DEWBOX quality 
cabinet. 2in x 2 1 z in x any length. 
D.E.W. Ltd., Ringwood Road, FERN- 
DOWN, Dorset. S.A.E. for leaflet. Write 
now — Right now. 

RECORD TV SOUND using our loud- 
speaker isolating transformer Pro- 
vides safe connection to recorder. In- 
structions included. 70p -f-lOp P&P. 
CROWBOROUGH ELECTRONICS 
(P.W.), Eridge Road, Crowborough, 
Sussex. 



12 VOLT 
FLUORESCENT LIGHTS 




Beat Power Cuts, 1 2 ins 8 wact Tube, Ideal 
for Caravan, Tent, Emergency Lighting etc. 
Fully Transistorised, Low Battery Drain, 
With ON/OFF Switch and I2v Socket to 
Run other Lights or I2V Equipment. 

Unbeatable ac f^*^fl 

or in kit for 



£2-90 



pose paid 



SALOP ELECTRONICS 
23 Wyle Cop 
Shrewsbury, Shropshire 



C.lle 



slcor 



S.A.E. for littt 



NO NEED TO WORRY ABOUT 
A TRANSMITTING LICENCE 

because this GPO approved transmitter/receiver 
kit does not use R.F. and you can gee one easily. 
Your transmissions will be virtually SECRET since 
they won't be heard by conventional means. 
Actually it's TWO KITS IN ONE because you get all 
the printed-circuic boards and components for both 
the transmitter AND receiver. You're going to find 
this project REALLY FUN-TO-BUILD with the 
EASY-TO-FOLLOW instructions. An extremely 
flexible design with quite an AMAZING RANGE— 
has obvious appl ications forSCHOOLPROIECTS. 
LANGUAGE. LABORATORIES, SCOUT CAMPS. 
etc. 

GET YOURS ! SEND £5-20 NOW 

TO: 'BOFFIN PROJECTS' 
DEPT. KW20I0 
A CUNCLIFFE ROAD 
STONELEIGH. EWELL. SURREY 



754 



Miscellaneous 

(continued) 




FLAME TIPS 

A precision tool using a com- 
bination ol bntane and com- 
pressed oxygen. U.S.A. manu- 
factured. Given two sizes ol flam< 
of pencil lead thickness. Adjustable temperatures up 
to 6.00CF. Lights instantly, no priming. Cut* 
metals, welds, brazes and solders, etc., gold and 
silver. Ideal for jewellers, clockmakers, silversmiths. 
Up to 40 minutes" operation using fuel supplied. 
Replacement set of 2 oxygen and 1 butane cylinders 
£1.60 inc. post. Complete with instructions. List 
price £14-50. Our price £9-99 + 31 p p. S p. Send 
£10-30. 

JOHH DUDLEY & CO. LTD., Dept. WP1 

301 Cricklewood Lane. Child's Bill, London. H.W.B. 

Tel. 01-458 5917. Callers welcome. 



AVO MARK 4 Valve Tester Perfect 
condition. £100. Tel. 437 3066. 



DAILY TJFO Flight Patterns, 37' 2 p.- 
UFO Map, S. England, 37' 2 p. TV 
Notes on UFO Detection, two Optical 
Circuits, 50p. UFO Wave Pattern and 
Prediction, 45p. R & P Publications, 
"Highlands," N e e d h a m Market, 
Suffolk. 



Wanted 



WE BUY New Valves and Transistors. 
State price: A.D.A. MANUFACTURING 
CO., 116 Alfreton Road, Nottingham. 



TOP PRICES PAID for NEW VALVES 

popular T.V. and Radio types. 

KENSINGTON SUPPLIES (C). 

367 Kensington Street. Bradford 8. 

Yorkshire. 



WE BUY New Valves, Transistors and 
clean new components, large or small 
quantities, all details, quotation by 
return. WALTON'S WIRELESS 

STORES, 55 Worcester Street, Wolver- 
hampton. 

CASH PAID for New Valves. Payment 
by return. WILLOW VALE, ELEC- 
TRONICS, 4 The Broadway. Hanwell, 
London, W.7. 01-567/5400-2971. 

HIGHEST POSSIBLE cash prices for 
Akai, B. & O., Brenell, Ferrograph, 
Revox, Sanvo, Sony, Tandberg, Uher, 
Vortexion, etc. 9.30-5.00. 01-242 7401. 

WANTED: Practical Wireless, Tele- 
vision, Electronics. 1960-1971. Ridley, 
472 Spen Lane, Leeds 16. 



Ladders 



LADDERS, timber, 20ft. £7, 29ft. 
£10-25. Carr. 80p. Brochure. Order 
C.O.D. Phone 02-993 5222 (Dept WLS) 
Home Sales, Baldwin Road, Stourport, 
Worcs. Callers welcome. 



Metal Work 



METAL WORK: Ail types cabinets, 
chassis, racks, etc., to your specifica- 
tions. PHILPOTTS METAL WORKS 
LTD., Chapman Street, Loughborough. 



Service Sheets 



¥ Service Sheets and Manuals * 

COVERING RADIOS, TELEVISION*, TAPE RECORDERS, RECORD PLAYER*, ETC. FROM 1833 UP-TO-DATE 
FROM 40P. EACH - 1071 SERVICE SHEET INDEX LIST 20P. - S.A.E. WITH ENQUIRIES PLEASE 

« NEW BOOKS A PUBLICATIONS ► Price + Post 

PRACTICAL OSCILLOSCOPE HAN0B00K by R.P. Turner. 236 po s .» £1.80 15p 

SERVICING TRANSISTOR RADIOS AND PRINTED CIRCUITS 263 MOM E2.S0 15p 

WIRELESS SERVICING MANUAL by W.T. Coekino. 286 poo.i £1.50 15p 

INTERMEDIATE ELECTRONICS by R.J. Moddock. Boole On*. 327 pages £175 15p 

INTERMEDIATE ELECTRONICS by R.J. Moddoek. Book Two. 314 MM* £2.75 ",5p 

GUIDE TO BROADCASTING STATIONS 16th Edition. 219 pogai £0.50 7p 

TELEVISION ENGINEERING Vol.2. Prlnclpl. • ondProctic. 296 Mg*f £3.50 25p 

MEASURING OSCILLOSCOPES by J.F. Golding. 272 poo.» £4.20 25e 

INTEGRATED CIRCUIT SYSTEMS by D.J. Woltor. 234 MM* £3.50 25p 

FIELD EFFECT ELECTRONICS by 3 «nin«nt Authors. 372 poo., £8.00 35p 

FM RADIO SERVICING HANDBOOK by G.J. King. 206 pog» £3.00 15p 

SEMICONDUCTORS: BASIC THEORY AND DEVICES by I. Komp.l. 272 pogt. £2.50 15p 

Send S.A.E. lor FREE' Li»t of Practical and Technical Book* on Radio & Television now available to - 

BELL'S TELEVISION SERVICES 

Albert Place, Harrogate, Yorkshire. Telephone 0423-86844 



SERVICE SHEETS. Radio, TV etc. 8,000 
models. List lOp. S.A.E. enquiries. 
TELRAY, 11 Maudland Bank, Preston. 



SERVICE SHEETS (1925-1971) for Tele- 
visions, Radios, Transistors, Tape Re- 
corders, Record Players, etc., by return 
post, with free Fault-Finding Guide. 
Prices from 5p. Over 8,000 models 
available. Catalogue 13p. Please send 
S.A.E. with all orders/enquiries. Hamil- 
ton Radio, 54 London Road, Bexhill, 
Sussex. Telephone Bexhill 7097. 



RADIO. TELEVISION and Tape Re- 
corders. 50 mixed odd sheets 50p. Also 
large stock of Obsolete/Current 
Valves. John Gilbert TV, IB Shepherds 
Bush Road, London W6. 01-743 8441. 
SAE enquiries. 



TRADER SERVICE SHEETS 

40p. each plus postage 

We can supply Trader Service Sheets for 
most makes and types of Radios. Tape 
Recorders and Televisions — Manuals for some. 



Cheques and open P.O.s returned if sheets not 
available. 

OAKFIELD ENTERPRISES 

LIMITED 

2t CHURCH ROAD, 
TUNBRIDGE WELLS, KENT 



Make 


Model 


Radio 17V 















1971 List now 
available at I0p 
plus postage 

From 

Address 



If list is required 
indicate with X 



enclose remittance of. 

(and a stamped addressed envelope) 
s.a.e. with enquiries please 

MAIL ORDER ONLY 



LARGE SUPPLIER 

OF 
SERVICE SHEETS 

(T.V., RADIO, TAPE RECORDERS, 

RECORD PLAYERS, TRANSISTORS, 

STEREOGRAMS, RADIOGRAMS, 

CAR RADIOS) 

Only 25p each. 

"PLEASE ENCLOSE LARGE S.A.E. 

WITH ALL ENQUIRIES * ORDERS" 

Otherwise cannot be attended to 

(Uncrossed P.O.'s pleas*, original 
returned if service sheet* not available.) 

C. CAR ANN A 

71 BEAUFORT PARK 

LONDON, N.W.11 

We have the largest supplies of 
Service Sheets (strictly by return of post). 
Please state make and model number 

alternative. 
Free TV fault tracing chart or TV list on 

request with order. 
Mail order only. 



Educational 



TRAIN FOR SUCCESS 
WITH ICS 



Study at home for a progres- 
sive post in Radio, TV & 
Electronics. Expert tuition for 
C & G (Telecoms Techn's Cert 
and Radio Amateurs') RTEB, 
etc. Many non-exam courses 
including Colour TV Servic- 
ing, Numerical Control and 
Computers. Also self-build kit 
courses — valve and transistor. 

Write for FREE prospectus and find out 

how ICS can help you In your career. 

ICS, DEPT. S4I INTERTEXT HOUSE, 

STEWARTS RD.. LONDON, SW8 4UJ 

"ACCREDITED BY THE CACC" 



RTEB CERTS., City & Guilds, Colour 
TV, Radio. Computers, Radio Ama- 
teurs Cert., Practical Electronics (with 
kit). Thousands of successes. Send 
for full details of Home Study Courses 
and illustrated book— FREE: BIET, 
(Dept. H.7), Aldermaston Court, Read- 
ing, RG7 4PF. 



755 



Educational 




TELEVISION TRAINING 

(MONOCHROME AND COLOUR) 
This private College provides theoretical and practical training in Radio and TV Servicing. Courses of- 16 
months' duration, with daily attendance, are available for beginners and shorter courses for men with 
previous training in Electronics and Radio. Training courses in Marine Radiocommunication and Radar are 
also available. Write for prospectus to: London Electronics College, Dept. A/12, 20 Penywern Road, 
Earls Court, London SWS 9SU. Tel. 01-373 8721. 



CIE, AMSE, City & Guilds, etc., on 
'Satisfaction or Refund' terms. Thou- 
sands of exam, successes. Postal 
Courses for all branches of Engineer- 
ing. Illustrated prospectus FREE. 
Please state subject of interest: R1ET, 
(Dept. H.8), Aldermaston Court, Read- 
ing, RG7 4PF. 

GO TO SEA as a Radio Officer. Write: 
Principal, Nautical College, Broad- 
water, Fleetwood FY7 8JZ. 



Situations Vacant 

EAGLE INTERNATIONAL require 
Audio Engineers; excellent prospects. 
Must be fully conversant with Stereo 
Amplifiers, Tuners, Multiplex, etc. 
Contact Mr. Morrow 01-903 0144. 



RADIO 

OPERATORS 

DO YOU HOLDPMG II 
OR PMG I OR NEW 
GENERAL CERTIFI- 
CATE OR HAD TWO 
YEARS' RADIO OPER- 
ATING EXPERIENCE? 

Looking for a secure job with good 
pa/ and conditions? 
Then apply for a post with the 
Composite Signals Organisation. 
These are Civil Service posts, with 
opportunities for service abroad, 
and of becoming established, i.e., 
non-contributory pension scheme. 
Specialist Training Courses (free 
accommodation) starting April and 
September, 1 972 and January, 1973. 
If you are British born and resident 
in the United Kingdom, under 35 
years of age (40 for exceptionally 
well qualified candidates), write 
NOW for full details and an 
application form from: — 

GOVERNMENT COMMUNICATIONS 
HEADQUARTERS, 

Recruitment Officer, 

Oakley, Priori Road, Cheltenham, Glos. 

GL52 SAJ. 

(Telephone: Cheltenham 21491, Ext. 2270.) 



Receivers and Components 

BRAND NEW COMPONENTS by 

return. Electrolytics 15 or 25V 1, 2, 5, 
10 mfds.-3-5p; 25, 50-4p; 100-5p. Mylar 
Film 100V -001, 002, -005 of -02-2p; 
■04, 05-2-5p; 068, l-3p. Mullard 
miniature Carbon Film resistors E.12 
series » 3 W in-10Mn 8. for 5p. Insured 
postage 8p. The C.R. Supply Co.. 127, 
Chesterfield Rd., Sheffield S8. 

756 



Receivers and Components 



electronics 

tupplv ••nl-i brand lira- yuuril'-r'rrf yovdi 

LOW HOISE HI-STABS 

i watt 0% all E24 values 3 (or 2p plus p. ft p. 8p. 

For up to SO resistors + lp (or each additional SO. 

■IHTEGRATED CIKCUITS- 



PA234 85p MTC4000P SSp (M709C **P 

P>287 I1M MKC4010P 76p /M7I0 45p 

Pa246 fl 80 TAA700 £2 nA741C 70p 
TRAHSISTOR8 Sl DIODES 



AC187/88 80p BC147 



AD101 
AD162 
BC107 
BC108 
BC109 



SSp 

pair 
12p 
Up 

_12P_ 



BC148 
BC149 
3STS709/3 

2N3704 



ISp 

m 

15p 

12p 
17p 



mrsToe/w 

10/ n 
2N3065 
2N2920 G 
2K17U 
DA8I/M/01 



2N3705/6/7 ISp B2Y88 



F.M. STEREO I.F. STRIP S3 -SO -'■ 
F.M. FRONT END £5 00 

F.M. flTEREO DECODER (5-25 



m 

55p 
16p 
25p 
7p 
ISp 



p. ft p. SSp 
p. A p. BSp 

p. A- p. 26p 



lOOpF 16v. 4p each. 
Mallard C431 series capacitors : 
GOOjxF -K. v 28p 2000/iF 2fiv 42p 4000/iF 25 v SSp 
1260/iF 2Sv 42p 2600-jiF 40v SSp 4000/iF 40v 77» 
1250/xF 40v 42p 2600/iF 64 v 77p also 

'■•■I2H (Op-. c-t:'.7. (">". (.':i:i3. s..mi.-.> .-■ |,..: : . -■ -r-n-. 



CARBON TRACK POT8. Single gang Log or Lin 12p 
Dual gang Log or Lin 40p. Mains Sw. 18p extra. 
SKELETON PRESETS. Vert, or Horiz. 0-lw Bp, 

0-26w 7p. 
MAINS TRANSFORMER. Bee. 2S0v 2SmA + 6-3v 

1-2A £1-90. 
S6, FORTIS GREEK ROAD. LOSDOH. H10 3HH 
1072 CATALOGUE lOp poit tne 
p. A p. an all orders other than resl'1'irn 6p. 



DON'T BUILD ANYTHING 

until you have seen what 
NIPPIBOARD can do 

Printed wiring board for everyone who 
makes up electronic circuitry, no 

matter what the size. 
One basic pattern for up to four 
transistor stages, or up to ten patterns 
for multiple complex systems. Write 
for FREE price list (send 2£p stamp). 

THE CHOICE IS YOURS 

but don't delay. SEND TODAY FOR 
YOUR sample NIPPIBOARD with 
FREE booklet. Only 15p plus postage. 

ALSO SL403D i.e. amplifier £1.99 
plus 9p postage and packing, 

NIP ELECTRONICS, Dept. NB/W12 
P.O. Box 11, St. Albans, Herts. 



TV's TV's TV's 

SPECIAL OFFER — LIMITED 
PERIOD ONLY 

19- aim Thorn 800 TVs 13 channel. 

Good working order. Polished cabinets. 

Only £9 SO PLUS HI -50 Carr. 

EX-RENTAL TVs (UNTESTED) 

Complete with 13 channel toners. Good cabinets. 

Carriage £1-50 extra. 

17' Semi 811m <90" Tube) . . . . £2 50 

17-/21- Slim (110° Tube) .. .. M-M 

19* Slimline £6-50 

23* Slimline 48-50 

19*BBC2SeM £14-50 

PERFECT SPEAKERS EX TV. 



Pin 3 obm (minimum order 
2 in. rectangular — 12jp each. 



two) S in. round. 8 in. by 
Add 7 ip per speaker p. A p. 



VALVES EX EQUIPMENT 



EB91 
EBF89 
EOC82 
EC180 
EF80 
KF8S 
EF183 
F.F184 
EY86 
S0PL13 
630LZ 
Add 2}p 



Sp 
12ip 
12tP 
7JP 
121P 
12ip 
12rP 
12iP 
17»p 
20p 
12»P 
per valv 



30L15 

30P4 

PC97 

PCF86 

PC84 

PCF80 

PCC89 

PCL85 

PCL82 

PCL88 

PCL83 

e p. ft p. 



12.P 
12JP 
17JP 
17ip 
7JP 
71P 
18ip 
22.P 
17ip 
17Jp 
12ip 
orders o 



22JP 
17Jp 
Up 
ISP 
7fP 
22.P 
17ip 
17.P 
22«P 
20p 
lOp 
er £1 p. ft p. free 



PL88 

PL81 

PT81 

PY800 

PY82 

PY33 

U191 

6F23 

30PL1 

S0P12 

30F5 



UHF TUNERS 



For Ferguson 850 900 chassis. Adaptable (or MDS UHF 
Chassis £2 50, p. ft p. 50p. 

SLOT METERS — SPECIAL 
OFFER 

Smiths Mk. 11 6d. Convertible to 5p. (Smiths Kit costs 
SSp each £1 each inc. p. ft pkg. or 10 (or £5 inc. p. ft pug. 
Please write with 8AE (or quotations on any spares. 

TRADE DISPOSALS 
(Dept. PW/TS) 

Thornbury Roundabout, Leeds Rd., Bradford. 
Telephone 665870 



VHF AIRCRAFT, Public Service band 
radios. FLIGHT 4: Medium Wave, 
FM 88-108, Aircraft 108-140, Public 
Service 140-175. AFC. 9in.X7in.X4in., 
£16. WALTHAM. MW/LW/SW/FM/ 
VHF 108-175. Battery/mains. AFC llin 
x 9in x 4in., £33. Full lists s.a.e. Money- 
back guarantee. Langtons Radio, High 
Street, ROCESTER, Staffordshire. Tel. 
388. 



AUDIO MIXER UNITS & KITS 

High quality MODULES and BOARDS for constructing complete 
mixers in mono and stereo or for amplifier front ends, etc., also 
complete custom built systems for high quality STUDIO, DISCO, 
and P. A. Installations at economical costs. 

PARTRIDGE ELECTRONICS 



Dept. P.W.I 2 
Essex 



21 /2S Hart Road • Thundersley 
Tel: South Benfleet 32S6 



Benfleet 

1478 



Receivers and Components 



f 



NEW MODEL V.H.F. KIT MK2 

Our latest Kit, Improved design and performance 
ploa extra Amplifier Stage, receives Aircraft, 
Amateurs, Mobile, Radio 2. 3, 4, etc. 
This novel little set will give you endless hours of 
pleasure and can be built in one evening. Powered 
by 9 Volt Battery, complete with easy to follow 
Instructions and built in Jack Socket for use with 
Earphones or Amplifier. 

Only (3-40. P. 4 P. Free U.K. only 

Illustrated Catalogue ol Selected KiU and Com- 
ponent! 12 1 p. P. & P. Free. 

Cheques, Postal Orders to: 
Dept. P.W.. 
Galleon Trading Co.. 25 Avelon Bold, 
Romiord, Essex 



COMPLETE RANGE of receivers by 
Trio, Lafayette, Hallicrafters, etc. 
Chassis, panels, cabinets. S.A.E. for 
lists. Stephens-James Ltd., 70 Priory 
Road, Liverpool 4. Tel. 051-263 7829. 

Stella Nine Range Cases 

LIST OF PRICES AND SIZES 

Width Depth 4" Height 6" Height 7±" Height 
6i" 3J" 90p £105 £1-23 

6i" 4}" 96p £1-23 £1-40 

81" 3t" £1-05 £1-40 £1-40 

8-T 6}" £1-40 £1-74 £2 00 

I0r 7i" £1 88 £2-28 £2-45 

I2i" 3J" £1-40 £1-74 £203 

124" 51" £1 -85 £2-25 £2-43 

124" 8 J" £2-30 £2-74 £2-93 

144" 33" £1-65 £2 03 £2 25 

144" 95" £2-73 £3 50 £3-65 

164" 6j" £2-45 £2-93 £3 24 

164" 101" £3 15 £4 05 £4-45 

Cases — Post 25p. per order. 
Discounts available on quantities. 

CHASSIS in Aluminium, Standard Sizes, 
with Gusset Plates 

Sizes to fit Cases. All 2V Walls 
6" X 3" 33p 10" •- 7" 5lp 14" x 3" 44p 
6" X 4" 34p 12" x 3" 40p 14" X 9" 84p 
8" x 3" 39p 12" y 5" 45p 16" x 6" 64p 
8" 6" 46p 12" > 8" 64p 16" .-. 10" 95p 
Chassis — Post 1 5p. per order. 

Discounts available on quantities. 
Electro magnetic counters. New Boxed 
500 ohm 4 digit 30p post free. 
Copper Laminate Board jfe" single sided. 
12" x 12" 30p. post free. 
P.O. relays (600 Type) 500 ohm + 
500 ohm. 1 make 1 break 2 change over 
New boxed 30p post free. 
Heavy duty sliding reostat. I ohm 12 amp 
New boxed £1 -25 p. post free. 



E. R. NICHOLLS 

Manufacturer of Electronic Instrument Cases 

46 LOWFIELD ROAD 

STOCKPORT - CHESHIRE 

Tel: 061-480 2179 



Receivers and Components 



EX COMPUTES PRINTED CIRCUIT PAHELS 
2ln X 4ln packed with si-mi-conductom and top 
■luality resls'ors, capacitors, diodes, etc. Our 
price 10 boards 60p. P. ■* P. 7p. With a guaran- 
tceil minimum of 35 transistors. Data on 
transistors Included. 

SPECIAL BAROAIK PACK. » boards for CI, 
P. A P. 18p. With a guaranteed minimum of 8ft 
transistors. Data on transistors Included. 



PANELS with I power transistors similar to 
OC28 on each board— components 2 boards (4 x 
OC23) SOp. P. i P. Hp. 



O.V5, 3 OA10, 3 Pot Cores, 26 Resistors. 14 
fapf.ritors, 3 GET 872. 3 OET 872B. 1 OET 876. 
All I ing leaded on panels 13ln X 4in. 4 for CI, 
P. 4 P. 25p. 



708C OPERATIONAL AMPLIFIER 

705 H lead I.C. 1 off SOp : SO off 86p : 100 off 20p. 



250 MIXED RESISTORS 

1*1 watt. 



62p 



150 MIXED HI STABS 62p 



}. *} A 1 watt n° S little 



QUARTZ HALOGEN BULBS 

Willi long leads. 12V 66W for car spot lights 
proj-ictnrs, etc. SOp each. P. 4 P. ftp. 



GPO EXTENSION TELEPHONES 
with dial hut without bell. 
9Sp each. P. « P. 30p. 
CI -75 for 2. P. * P. SOp. 



BARGAIN RELAY OFFER 

Sinwle pole change over silver contacts CSV to 
30V. 2-3kfi coil, n for SOp. P. 4 P. 6p. 



KEYTR0NICS mail order only 

44 EARLS COURT ROAD, 
LONDON W.8 01-478 8499 



MICRO-CIRCUITS: 

SN76013 (like IC12. C1-S0: 709 8«p: 741 3«p: PAS80 »0p: 
P.VJ34 86p: PA237 CI 68; SL402A Cl-76: 8LTO9C 40p: 
TT1. IATE3 15p: FLIPFL0P3 37p. 

TRANSISTORS: 

■JN305J. Mp: BC107B 9p. BC108C 9p: BC109C 9p 
BCY 70 18p: BFX80 15p: ME0402 21p: ME0411 20p 
ME0412 SOp: ME0413 16p: ME1002 lip: ME4101 Up 
MF.4102 lgp: MEOIOl 16p: ME6102 19p: ME8001 17p 
SIP8111 35p: MP8U2 45p. 

1 AMP RECTIFIERS 

80V 8p: 100V 4p: 200V Sp: 400V 6p: Bridges: 50V SOp; 

100V Sip: 400V 33p. 

3 AMP RECTIFIERS: 400V 12p. 

PRINTED CIRCUIT RESIST PEN 80p. 

JEF ELECTRONICS (P.W.12) 

York House, 12 York Drive, Grappenhall, 
Warrington. Lanes. Mall Order Only. C.W.O. 

P.&P. 7p per order. Overseas 50p. 

Money back II not satisfied. 

List lree on application. 



LOOK AT THESE PRICES! 

ALL DEVICES BRAND NEW FULLY TESTED AND GUARANTEED 

Integrated Circuits TTL LOGIC Dual in line 

7400, 01, 02, 04, 05. 10. 20, 30, 40.50, 51,53, 54. 60 ALL I5p ea. 

7441, 42, 80. 83. 90. 92. 93, 94. 95. ALL 67p ea. 

7481, 82. 91. 118. 145, 151, ALL 95p ea. 7470, 72, 30p ea. 75. 76. 45p ea. 

7473, 74, 40p ea. 86. 121, 50p ea. 7447, 90p ea. 

Silicon Rectifiers 

50v lOOv 200v 

4p 4-5p 5p 

4-5p 4-5p 5p 

I3p I5p I9p 

Integrated Circuits Linear. D.I.L. or TO-5 
709, 40p 
Discounts 10% Orders over £2 



P.I.V. 
JA 
IA 
3A 



400v 
5p 
6p 
2lp 



600v 
8p 



800v 
lOp 
I2p 

25p 



lOOOv 
I3p 
I4p 
28p 



741. 60p 
5% over £5. Post A Pack. 5p 



Mail Order Only 

D j COMPONENTS 

I4B, SUSSEX ROAD. HARROW, MIDDLESEX 



RADIOSPARES COMPONENTS as 

specified for P.W. Digital Counter. 
Midget Mains Transformer, £1-75, 
p. & p. 25p. Min. wire neons, 12p each, 
p. & p. 5p. Min. Maka-Switch shafting 
assembly, 40p. Spacers, 7p pkt. M-B 
wafers, 28p each, p. & p. on com- 
plete switch, 12p. We supply all 
'Radiospares' components. S.a.e. with 
enquiries: The Hobbies Shop, 32 The 
Parade, Cwmbran Town Centre, 
Cwmbran, Mon. 



i— LOW PRICED —| 

SEMI CONDUCTORS 

ALL OCR STOCKS ARE BRA1-7D N'KW, NO 

REJECTS. SO SECONDS. ALL CIUARAN- 
TEED. P. & P. Sp 
TRANSISTORS 

AC 187K \ 4Sll 8S 3055 SSp 

AC188KJ •• ™ p AD 142 .. 50p 

BC 107 . . Sp 

BC 108 . . 8p 



AC 141 K 20p 

AC 142 K . . 20p 

AX 102 . . 80p BC 109 . . 8p 

AC 103 .. 90p BC 142 .. SSp 

AL 102 .. 60p BC 143 .. 35p 

AC 103 .. SOp -.JJ 3860 . . L86p 

BDloi} • W BF ™ • "> 

Matched Pairs BFY 52 .. lOp 

DIODES & RECTIFIERS IS 40«1 .. 7p 

400m. W ZENER DIODE IN 4004 .. Sp 

fl-8v. 7-Bv, 8-2v. 9-lv 15p IN 4148 , . 6p 

SEND FOR FREE PRICE LIST. INCLUDES 
HUNDREDS OF TRANSISTORS, CAP'S. 
T.T.L's ETC. FREE EQUIVALENT CHART. 

C. HADLEY (P.W.) 

24 WOODHILL. HARLOW. ESSEX. 



hot; news 

Nippiboard Range 'B' 

NEW FIBREGLASS TYPE 
Version of the srbp range A' 

NOW AVAILABLE: 

Dept. NBAWI2. NIP Electronics 
P.O. Box II. St. Albani. Herts. 



CIRCUITS CIRCUITS CIRCUITS 

Ten exciting circuits per month with Instruc- 
tions to build. Every month a completely 
new set. This month's circuits cover 

MISCELLANEOUS PROJECTS 

Only 50p per set of ten p & p free 

Free Data and Technical A-Z cards (build 
u? the complete set month by month) . 
Cheques and PO to Dept PVVC, Photronics. 
3 Whitehall Gardens. London. E4. 

TRANSFORMERS for all transistor 
projects. Prices reasonable. Rewind 
service available. S.a.e. details: Rat- 
cliffe, 18 Beech Avenue, Thongsbridge, 
Huddersfield. 

EX-GOVT. COMMUNICATIONS RE- 
CEIVERS, calibrators, signal genera- 
tors, components, etc., with money 
back guarantee. S.A.E. list. Callers 
welcome, please phone first. P, R. 
Golledge, G3EDW, Glen Tor, Torring- 
ton, Devon. (STD 08-052) 2411. 



For Sale 



MORSE 



MADE 
EASY 



I I 



FACT NOT FICTION " you «t«i RIGHT 

you will be reading &niateur ainl fMIWflwM Muroe 
Within a month (normal progress to be expected). 

Using scientifically prepared 3-speed record.** you 
automatically learn to recogui-e the code RHYTHM 
without translating. Yon can't help it, it's an ea»y a* 
learning a tune. 18 W.P.M. in 4 weeks guaranteed. 

For details and course C.O.D. ring S.T.D. 01-060 '289fi 
or send 4p stamp for explanatory booklet to: 
Q3HSC (Box 19), 45 GREEK LAKE. P0RLEY, SURREY 



SEEN MY CAT? 5,000 items. Mechani- 
cal & Electrical Gear, and materials. 
S.A.E. K. R. WHISTON, Dept. PW, 
NEW MILLS, Stockport. 



757 



For Sale 



FOR SALE FULL STEREO SYSTEM 

Akai X-150D Crossfield tape deck, 
Pioneer AM, FM, Multiplex receiver, 
two Akai cabinet speakers 12in. 
woofer 3'2in. tweeter in each. All 
finished in teak as new cost over £450 
accept £200 must sell. 47 Edge View 
Walk. Kinver, nr. Sto urbridge, Worcs. 

VALVE CARTONS for sale: EL84 size. 
S.A.E. for Sample and Price. Berwick, 
100 Tib Street, M anchester 4. 

NEW VALVES! 

Guaranteed and Tested 
24-HOUR SERVICE 



i itr> 

ISA 
1T4 
384 
3V4 



•55 



8Y3GT 85 

S/30J/2 63 

6A«5 -21 

SBW7 50 

SF1 -S7 

c !■-.'.» 

tsna 

GSN70T 88 

26L-6DT 80 

SOCIO -68 

S0O18 -59 

80F8 -67 

30FLI -59 

son. 1. 1 ov 

SOL 1ft -58 

30LI7 -88 

30P4 -58 

30P19 -58 

30PI.1 -69 

30PL13 73 

30PLI4 -63 

DAK1H -21 .. 

DAF9A -35 | KF80 

DCC00 -80 ' BF8S. 
Postage on 1 valve 5p. 



DF91 
DF96 
DK91 
nK9-2 
DK9S 
DIA2 
DL94 
DL96 

DY86 -84 

DYB7 -84 

DY802 -80 
BABC80 -30 

EB9I -10 

KBC33 -38 

BBFH9 -87 

BCC81 15 

ECC82 18 

B0088 -21 

accsa -24 

F.CF80 -88 

ECF82 -88 

F.CH35 -87 

BOH81 -26 

F.CL80 -29 

ECL82 -89 

ECL81) -85 

F.F39 -36 



■37 



EF86 

EF89 

JSF91 

EF183 

EF184 

EL33 

eu; 

EL84 
EY51 
EY86 
EZ80 
EZ81 
KT61 
KT6B 
N78 
PC86 
PC88 
PC900 
PCC84 -88 
PCC89 -48 
PCC189 -47 
PCF80 -87 
PCF86 -43 
PCF80L -89 
PCFS02 -88 
PCF805 -59 
PCL82 -80 
PCL83 -55 
PCLS4 -83 



•29 I PCL83 -87 
-24 PCL80 -88 
12 PFL200 -68 

PL38 

PL81 

PL82 

PL83 

PL84 

PLS00 

PL504 

PY81 

PY82 

PYSOO 

PY801 

R19 

C28 



T.T26 

U19.1 

U251 

V329 

CBF89 89 

UCC85 

1JCH81 

VCL82 

CCL8S 

CF89 



UL84 
UY85 
Z77 



I valves 3p per vah 



:trs. Any nan-el insured against damage in transit 3p 
eitra. Oltlce address, no callers. 

GERALD BERNARD 

83 OSBALDESTON ROAD, 
STOKE NEWINGTON, LONDON. N.I6 



CLEAR TONE HI-FI LTD 

166 BLACKBURN ROAD. BOLTON BLI 8DR LANCS. Tel.: 22636 



•ITEMS STARRED ON COMPARATOR DEMONSTRATION 



Rec. 

Retail 

STEREO AMPLIFIERS (Cased) 

*Tripletone Gemini 3 Mag- 
netic Input 

•Alba UA700 

•Meirosound ST20E 

•Rotel 310 

•Rogers Ravensbrook 2 ... 

•Armstrong 521 

•Leak30^- 

•Rogers Ravensbourne ... 

•Leak 70 

CARRIAGE £1-00 
SPEAKERS 

•Wharfedale Denton 2/pr. 
•Wharfedale Linton 2/pr. 
•New Leak 150/pr. 
•R. Allen Flamenco/pr. ... 
•New Leak 250/pr. 
•R. Allen Pavane/pr. 
•Wharfedale Melton 2/pr. 
•Celestion Ditton IS/pr. ... 
•Wharfedale Dovedale 3/pr. 
CARRIAGE £100 
CARTRIDGES 
•Sonotone 9TA/HC Dia ... 
•Goldring G850 Dia. 
•Goldring G800 Dia. 

•Shure M44.7 Dia 

•Goldring G800E Dia. ... 

•Shure M55E Dia 

•Shure M75E/2 Dia. 
CARRIAGE FREE 

TURNTABLES 

•Garrard SP2S Mk. 3 

•McDonald MP60 

•Goldring GL69/2 

•Goldring GL69/2/P 
•Connoisseur BD2/SAU2 ... 



£28-50 
£34-50 
£39 50 
£45-00 
£52-50 
£56-00 
£62 50 
£64-00 
£75 00 



£39-90 
£49-90 
£49-90 
£59-26 
£65 00 
£70-50 
£70 00 
£76-94 
£90 00 



£3-75 
£6-27 
£12-55 
£9-84 
£18-16 
£12-52 
£20 57 



£15-85 
£15-20 
£27-60 
£36 21 
£31 00 



Our 

Price 



£17 00 
£24 00 
£27 50 
£32 00 
£40 00 
£45 00 
£44 00 
£49-00 
£54 00 



£32 00 
£41 00 
£41 00 
£46 00 
£48 00 
£49 00 
£50-00 
£60 00 
£65 00 



£2 00 
£4 00 
£6-50 
£7 50 

£1100 
£9 50 

£14 00 



£10 50 
£11-20 
£21 50 
£27-50 
£25 00 



Rec. 
Retail 

£38 00 
£4015 
£48-76 
£71-26 
£6-00 



Our 
Price 

£33-00 
£30 00 
£36 00 
£53 00 
£4 00 



•Connoisseur BD2/SAU2/ 

P/C 

•Goldring GL75 

•Goldring GL75P 

•Garrard 401/3009/2 arm ... 
PI Spacer and Mtg. Board ... 

Plinths and Covers Stocked 
CARRIAGE £100 

SPECIAL OFFERS 

Garrard SP25 Mk 3 fitted in Teak 
Veneer Plinth with Cover wired 

Din or Phono to order £1300 

with 9TA/HC Cartridge £15-00 

with G850 Cartridge £17 00 

with G800 Cartridge £19 50 

SME 3009 Mk 2 Arm & Shell £33-80 £24 00 

Connoisseur BDI Kits ... £1300 £10 50 

Connoisseur SAU2 Arms ... £14-40 £12 00 

CARRIAGE AND INSURANCE ON ABOVE 
ITEMS £100 

ALL ITEMS GUARANTEED. AFTER 
SALES SERVICE. PRICE LIST ON 

REQUEST. 



•Leak Delta 30 
♦Leak Delta 70 
•Leak Stereofetic/30 
•Leak Stereofetic/70 
CARRIAGE £100 



... £6500 £52 00 

... £7950 £62 00 

... £131 03 £94 00 

... £143-53 £103 00 



■ ; i«j Baa 

OPEN 9.00-5.30 Monday-Tuesday 
9.00-8.00 Thursday-Friday 
9.00-4.00 Saturday 
CLOSED ALL DAY WEDNESDAY 
CLOSED 1.30-2.30 Except Saturday 





AMPEX 7-5v. D.C. MOTOR. This 
is an ultra-precision tape motor 
designed for use in the AMPEX 
model AG20 portable recorder. 
Torque 450GM/CM. Stall load at 
500ma. Draws 60 ma on run. 600rpm 
x 5% speed adjustment. Internal 
AF/RF suppression 4." dia. 1" spin- 
dle, motor 3" dia. 14". Original coBt 
£16-50. Our price £4-25. P. 4 P. 
25p. Mu-metal enclosure available 
75p each. 
SYNCHRONOUS MOTORS. 220/380 v. 50/60 Hz. 
250-300 rpm. 75p each. 

MYCALEX MAINS. Shaded pole, 1425 rpm, *» 
spindle. 2 lor £1-25. Carriage Paid. 
MAINS INDUCTION MOTOR. Open frame, tV 
spindle, weight} lb. Powerful. 88p each. P. & P. 12p. 
GEARED MOTORS 
"Parvalux" Reversible 100 
RPM Geared Motor. Type 
S.D.14, 230/250v. A.C.22 Ib./in. 
4" spindle. 1st class condition. 
£7-50 each. P. & P. 50p. Also 
limited number only as above. 
Brand New. £12-50 each. 
P, 4 P. 50p. 

ELECTRO CONTROL (CHICAGO). Shaded pole 
240v. 50 Hz. 200 rpm. 101b. in. £2-50, P. & P. 25p. 
MYCALEX. Open frame, shaded pole motors, 240v, 
50 Hz. 7 rpm. 28 lb. in. 80 rpm. 12 lb. in, £2-25 each. 
P. 4 P. 25p. 

"CROUZET" TYPE 965. 115/240v. 
50 Hz. 47/68 watts. 50 rpm. Stoutly 
constructed. Size: 2+i" dia. x 3»~ long 
plus spindle 1" x i" dia. Anti-clock. 
£2-75. P. 4 P. 25p. 
TYPE 955. Same as above, but 3 rpm. £300. P. 4 P.25p 
UNISELECTORS. 8 Bank 25-way, 24 volt Double 
sweep. Brand new in maker's boxes £5-25 P. 4 P. 25p. 
PAINTON BOURNS TRIMPOTS. 1k, 2k, 2-5k, 5k. 
10k, 20k, 50k, 500k. Other Trimmer pots in stock. RIL 
10k. MORGANITE 1k. MEC 200 fi (tubular) 50£J. Any 
3 for £1-10 carr. paid. 

CURRENT FLOW INDICATOR. 
Ideal for all types of battery opera- 
ted equipment (portable machines, 
tape recorders etc.). Four white 
segments appear when current 
flows. Coll is 6000 6 12v. Drawing 
only 8 ma on function. Neat in 
appearance. Size: dia. -rV" x tV* 
deep. Fixing centres H". £1 -25 each 
Carr. Paid. 



ELECTROTECH SALES 





PRECISION FAN CO. (SMITHS INDUSTRIES) 
DOUBLE ENTRY CENTRIFUGAL FAN BLOWER. 

This Is a beautifully balanced particular y quiet 

running unit giving approx. 90 

cubic ft./min. The motor is a 2 pole 

shaded pole Mycalex, drawing only 

240ma on run. Welsh! 2a lbs. 

Sizes: case dia. 3 1 Ins. width 

(case only) 3 125 Ins. Width 

overall (inc. 5-25 Ins. Aperture 

3-125 ins. x 1-85 Ins. Offered well 

below makers price at £2-95. 

P. 4 P. 25p. 



Brand New -DISCUS" Contri- 
fugal Blower by Watkins & 

Watson. 240v. 50 Hz. Powered by 

A.E.I, continuous rating 2850 rpm 

motor. Cowl diameter 10". Outlet 

flange 2" i.d. Coupling flange 

supplied. These superb precision 

units are ideally suited lor Organ construction. 

Offered at approx. hall makers price £12-50. Carriage 

£1-50. 



PLEASE NOTE OUR NEW ADDRESS AS 
BELOW. WE HAVE A LARGE RANGE OF 
INTERESTING ITEMS TOO NUMEROUS TO 
LIST. COME AND BROWSE AT YOUR 
LEISURE. HOPE TO SEE YOU SOON I 



SYLVANIA MAGNETIC SWITCH— a magnetically 
activated switch operating in a vacuum. Switch speed 
— 4ms. temperature — 54 to +200°C. Sliver contacts 
normally closed rated 3 amps, at 120v.1-5 amp. at240v. 
4 lor £1, or £2-50 per doz. Special quotations lor 100 



PROGRAMME TIMER BY HONEYWELL 

A bank ol 15 micro-switches are each independently 
operated by 15 pairs of cams which in turn are Indi- 
vidually adjustable to give switching periods of zero 
to 12 seconds with infinitely variable combinations. 
A mains synchronous motor drives the cam shalt at 
1 rev. per 12 seconds (5 R.P.M.). 
Originally cost £1500 plus. 
Many applications such as light- 
ing effects etc. New in original 
makers cartons. First class val- 
ue at £5 75 plus 25p. P. 4 P. 




Special offer of AMPEX professional tape heads, 
mu-metal shrouded. (Designed for model AG20). 
Full track record, or playback, £300. Erase head £2-00 
Set of 3 with mounting bracket and cover £7-50. Half 
track record only, £3-00 each. Carriage paid. 




tfesir 



"BENSON BROS". 12v. D.C. HEAVY DUTY 

SOLENOID. Size: 3" overall x U" x 1". Very powerful, 
with secondary low current hold coil, Cont. rated £1 00 
each. P. 4 P. 15p. 

"DECCO" MAINS SOLENOID. Compact and very 

powerful. 16 lb. pull. J" travel which can be Increased 

to 1" by removing captive-end-plate. Overall size 

2"x2i"x2J"hlgh.£1-50. P. 4 P. 25p. 

"MAGNETIC DEVICES" Mains Solenold:-2" x U" x 

1J"approx.2lb. pull. Plunger Travel 1»". New in makers 

boxes; offered at half original cost. 75p. P. 4 P. 25p. 

"MALLORY" LONG LIFE 

BATTERIES. Type A. RM12 cell 

1-35v. 3,600 ma/H. CAP. 250/300 ma 

cont. current. Size: 2" x J". 5 for £1 00 

or £2-00 per doz. Carr. Paid. Type B. 

Comprises 8 x RM 625 cells. Norn. 

volts. 1 35 each 10-5v. Overall, 

350ma/H CAP. 20/25 ma cont. current. 

Size: 2-rV x 4" x 4". 3 for £100 or 

£300 per doz. Carr. Paid. 

BONNELLA " CHERRY " ROLLER 
LEVER OPERATED MICRO- 
SWITCH TYPE B23-30K. 5 amp. c/o. 
502 operating pressure. Length of Leve 
V . Pre-travel -062". £2 25 per doz. 
ERNEST TURNER SOOfiA METER. / 
160n movement, 2" case elliptic, plastic! 
tront, Green-Red-Green uncalibrated' 
scale £1-50 each. Carriage paid. 
L.T. TRANSFORMERS. Prim. 0-110-240v. Sec- 4 5- 
^' 5v ^-n 1 - amp ^ Si2e ** * 1 * x 1-rV- 60p. P. 4 P. 15p 
Prim. 220240 v. Sec. 0-5-10-15-20 v. at 2 amps, £12$. 
P. 4 P. 15p. 

Prim 200/240V Sec 0-1-56-58-60 at 3-5 amps plus 0-90 
fi, - LPS , wa * impregnated with screw term blocks. 
Weight 10 lbs £3-60 plus 40p P. 4 P. 
"WODEN" Prim. 0-110-200-220-240v. Sec. 34-36-38v. 
@ 600va. £7-50 plus 50p. P. 4 P. 
"WODEN". Prim . 10-0-200-220-240v. Sec. two separate 
■vindings 6v. @ 4a each. £2-50 plus 30p. P. 4 P. 




BUSINESS HOURS: 
9.30-6 (I p.m. Sat.) p.w.io 



301 EDGWARE ROAD, LONDON, W.2 

Tel. 01-837 7401/2 



758 



All priets In pounds and new pane* 



VALVES 

1A7QT 40 
1CP31 £6-00 



1D5 

1H5 

IN6GT 

IR5 

184 

185 

IT4 

3A4 

3Q4 

3Q5 

3S4 

3V4 

5R4GY 

5T74Q 

5V4G 

8Y3GT 

SZ4G 

6/301.2 

6A7 

6A8G 

6AKB 

6AM6 

6AM6 33 

6AQ5 88 

6A87G 86 

6 AT 6 30 

6AU6 25 

6B4G £1-00 

8B8G 26 



6BA6 

6BE6 

6BH6 

6BJ6 

6BQ7A 

6BR7 

6BR8 

8BS7 

6BW6 

6BW7 

6C4 

6C5G 

6C6 

6CD6G 

6CH6 

6CW4 

6D6 

6E5 

6F1 

6F5G 

6F6G 

6F8G 

6F11 

6F13 

6F14 

6F23 

6F24 

6F25 

6F28 

6F32 

6G6 

6H6 

6J5M 

6J5G 

6JSGT 



25 

30 
75 
60 
45 
00 
70 

11-30 
85 
80 
33 
30 
26 

«-2£ 
60 
65 
25 
60 
70 
75 
35 
35 
40 
45 
70 
85 
75 

£1-00 
65 
25 
25 
28 
50 
20 
30 



6J6 

6J7M 

6J7G 

6J7GT 

6K6GT 

6K7M 

6K7G 

6K7GT 

6K8M 

6K8G 

6K8GT 

6K25 

6L6G 

61.18 

6Q7G 

6Q7GT 

6SA7M 

68C7M 

68G7M 

6SH7M 

6SJ7GT 

6SK7GT 

6SL7GT 

6SN7GT 

6SQ7GT 

8U4GT 

6UBG 

6V6M 

8V6G 

6V6GT 

6X4 

6X5G 

6X6GT 

7B6 

7B7 



20I7C5 

45 70S 

30 7 Li.'. 

45|7H7 
60I7R7 

85 '787 
20.7Y4 
35I9BW6 

60 10C-J 
40ll0Fl 



40 



10F3 
10F9 
10F18 
10LD11 
10P13 
11E3 
12AT6 
12AT7 
12A06 
40ll2ATJ7 
40.12AX7 
40 12BA6 
36 12BE6 
35 12C8GT 
40 12E1 



£1-13 
76 
55 

35 

701 
£2-25 
65 
60 
50 
76 



40 3 
SO 42 
40 

50 



12J5GT 

12J7GT 

12K7GT 

12K8GT 

12Q7GT 

128A7GT 

12SG7 

128H7 

128J7 

128K7 



£4-00 
80 
38 
36 
30 
30 
40 
40 
35 

£1-80 



123R7 

14H7 

19AQ5 

20D1 

20 F2 

20L1 

20P4 

20P6 

25A6 

25L6GT 

26Y6 

25Z4 

25Z5GT 

25Z6 

30C1 

30C15 

30C17 

30C18 

30F6 

30FL1 

30FL13 £l-CO 

30FL14 89 



70 
£1-10 

£1-10 

£1-20 

36 

60 

60 
45 

50 
65 
30 
80 

90 
SO 



40 

50 

SOBS 60 

50C6 BO 

50CD6G £1-20 
60L6GT 66 
50 

45 

55 
50 
60 
60 
50 
50 



DAF91 80IEBL31 £1-50;EL41 60 

DAF943 45 r.(".>0 88.EL42 66 

" ■ EL84 a 

EL95 35 

ELL80 £1-00 



80 

86A2 

150B2 

150C4 

801 



DCC90 £1-00 

DF33 48 

DF70 48 

DF91 SO 

DF92 20 

DF96 46IECC88 
DH3-91M-00 ECH21 



ECC81 
ECC82 
ECC83 
ECC84 
ECC85 



807 

813C3A£3-75 



866A 

9S4 

1626 



85 4022AR £5-00 



30L15 

30L17 

30 P4 

30P12 

SOP 19 

30PL1 

30PL13 

30PL14 

35 AS 

36L6 

35 W4 

3SZ3 

35Z4GT 

35Z5 



86 
80 
£1-12 
80 
85 
76 
93 
90 
76 
50 
35 
70 
50 
40 



70 
20 
40 
48 
86 
60 
60 
£4-00 
60 
48 
66 
CBL31 £1-00 
CCH36 75 
CL33 £1-30 
CY30 63 

CY81 48 

DAC32 42 



5763 

7193 

7475 

A61 

ATP4 

ATP5 

ATP7 

AU2 

At'S 

AZ1 

AZ31 



nil: 

DK32 

DK91 

DK92 

DK96 

DL66 



DL92 
DL93 
DL94 
I '1.05 
DL96 
DM70 
DY86 
DY87 

KMMX' 
60 EA.IO 
EABC80 
EAF42 
EB91 
EBC33 
EBC41 
EBC90 
EBF80 
EBF83 
EBF89 
Kill. I 
EBL21 



30 
40 
40 
60 
60 
£1-26 
86 



ECH35 £1-00 
ECH42 75 
ECH81 80 
ECH83 46 
ECL80 46 
ECL82 36 
ECL83 70 
ECL86 40 
ECLL800 

£1-65 
EF9 76 



40iEF37A £1-20 



33 EF39 



Transistors 



1N914 
1S113 
18202 
2G302 
2G371 22 

2K404 20 



2N2218 

2N2219 

2N23G9A 

2N2646 

2N2904 

2N2926 

2N3055 

2X3702 

2X8819 



2N4289 
AAZ12 
AC126 
AC127 
AC128 
ACY20 
ACY39 

10.AD140 

S5| 



A I) 140 
AD161 
AF115 
API 17 
A8Y26 
BC107 
BC108 
BC109 



60 IR'lfWC 
87 BF898 
26 BFY60 
26 BFTtBl 
25 BY 100 
10 BZY88 
10 CR81-40 

io'ddoos 

IGET102 



EF41 

EF50 

EF80 

EF85 

EF86 

EF89 

EF91 

EF92 

EF98 

EF183 

40 BK1H4 

80 ' K L32 

70.EL33 

60 ' EL34 



50 
66 

25 
25 
85 
80 
28 
33 
86 
76 
80 
35 
80 
£1-25 
SO 



EM34 

EM80 

EM81 

EM84 

EYB1 

EY86 

EZ35 

EZ40 

EZ41 

EZ80 

EZ81 

GYS01 

GZ30 

GZ32 

GZ34 60 

HX309 £1-60 

KT36 £1-00 

KT61 £1-25 

KT66 £2-05 

KT81 £1-75 

KT8K7CS) 

£1-13 
KT88 £2-00 
KTW6161-00 
KTZ41 46 
ML4 88 



£1-50 
£1-50 



Ml.''. 
M8P4 
MU14 
MX40 



X78 

X108 

OA2 

OC3 

OZ4 

PC86 

PC88 

PC97 

PCC84 

PCC89 

PCXJ189 

PCF80 

PCF82 

PCF84 

PCF86 

PCF801 

PCF802 

PCF80S 

PCF806 

PCF808 

PCL82 

PCL83 

PCL84 

PCL85 

PCL86 46 

PDSOO £1-30 

PENA4 £1-00 

PENB4 £1-00 

PEX45 75 

PEN46 40 

PL36 65 

PL81 60 

PL82 46 

PL83 45 

PL84 40 

PL500 80 



PL504 80 

FL508 80 

PL509 £1-10 

PLS02 96 



PX4 

PX25 
PY33 
PY81 
PY82 
PY83 



£2-00 
£2-50 
68 
30 
85 
88 



PY50O £1-00 
PY800 40 

PY801 



R2 

R19 

8130 

SP4 

8P41 

8P61 

8TV280/80 

£10-00 
SU25 £1-00 
8U2150 75 
T41 £1-00 
TDD4 
TH41 
U10 
U14 
U19 
G25 
036 
078 
U191 
U251 
0801 
U403 



£1-75 
50 
60 
75 



50 
£1-75 
60 
60 
£3-00 
80 
80 
35 
75 
80 
68 
60 



TJ404 60 

U801 £1-18 

UABC80 40 

UAF42 

CBC41 

UBC81 

CBF80 

UBF89 

CCC84 

UCC85 

UCF80 

I7CH42 

UCH81 

UCL82 

UCL83 

UF41 



UF89 

VL41 

UX84 

UM80 

UTJ6 

UTJ7 

VV8 

009 

UY21 

UY41 

CY85 

VMP4G 86 

VP4B £1-26 

VR105/30 88 

VR1S0/30 86 

VU111 78 

VU120 £1-00 

VU608 £2-60 

W81M 63 

Y63 50 



56 
50 
40 
40 
86 
48 
40 
66 
70 
40 
86 
60 
60 
40 
65 
40 
28 
£1-05 
£1-05 
£1-06 
45 
60 
48 
40 



15 BBT883 
28 GJ7M 

22 KM"" \ 
20 1 MJES20 

15 MJE29B5 
16 1 £1-37,0 AH I 
47IMJE305S 87IOA85 

16 NKT212 27:OA91 
80|XKT'214 16IOA211 



26I.SKT223 
S7|NKT2B1 
25 NKT7I.1 
87|OA70 
OA71 



OAZ200 
OAZ201 
OAZ207 
OAZ210 
OAZ222 
OAZ224 
OAZ241 
OAZ242 
OAZ246 



OC35 
OC44 
OC46 
OC57 
OC58 
OC59 
OC71 
OC72 
OC81 



OC81D 


20 


OC82 


26 


OC82D 


20 


OC84 


25 


OC170 


25 


OC171 


ao 


OC200 


40 


OCP71 


in 


ORP12 


5U 



Z8170 

Z8271 

ZTX107 

ZTX108 

ZTX300 

ZTX304 

ZTX500 

ZTX803 

ZTX531 



TRANSISTOR POSTAGE 1p EACH, OVER 10 POST FREE 

Express Postage & Insurance Sp one valve plus Ip ... 

each additional valve. ORDERS over £5 Post free. 6,000 types in stock send for lists, 5p. 



R.S.T 



"Renowned for Service 



99 



BLACKWOOD HALL, WELLFIELD RD., STREATHAM, SWI6 2BS 

Tel. 1 -769-0 1 9?/ 1 649. Open to callers Mon-Sat 9 a.m.— 5 p.m. Closed Saturday 1.00—2.30 p.m. 



INDEX TO ADVERTISERS 



A. H. Supplies 714 

AKG Equipment 668 

AMCCo 704 

Adcola Products Ltd cov. ii 

Antex 682 

Audio Supplies ... ... ... ■-■ 675 

Audioscan 754 

Baker Reproducers Ltd 732 

Belding Bennett & (Morse) 757 

Bell's Television 755 

Bentley Acoustic Corporation Ltd. ... 732 

Bernard. Gerald 758 

B.I.E.T 680, cov. iii 

Bi-Pak Semiconductors 744-5 

Bi-Pre-Pak Ltd 667 

Boffin Projects 754 

British National Radio School ... 725,750 

Broadway Electronics 696 

Bull, J. Electrical Ltd 663 

Bush & Meissener Ltd 660 



Caranna, C. 755 

Chromasonic Electronics 756 

Clear-Tone-Hi-Fi Ltd 758 

Codar Radio Co 743 

Colomor (Electronics) Ltd 728 

Comet High Fidelity Discount 

Warehouse 678-9 

Concord Electronics Ltd. 661 

Coventry Movement ... ... ... 660 

Crescent Radio 743 

C. &S 754 



Debar Electronics 674 

Data Publications Ltd 666 

D.E.W. Ltd. 754 

D. J. Components Ltd 757 

Duke & Co. (London) Ltd cov. ii 

Electro Value 695 

Electro-Tech. Sales 758 



Pelstead Electronics 728 

Field Electric Ltd 746 

Francis, George 692 

Francis. J. J. (Wood Green) Ltd. ... 676 

Galleon Trading Co 757 

Glads:one Radio 728 

Global Audio Discount Warehouse ... 662 
Government Communications 

Headquarters 756 

HAC Shortwave Products 660 

Hadley 757 

Harverson Surplus Co. Ltd 731 

Heath Glos. Ltd 669 

Henry's Radio Ltd 736, cov. iv 

Home Radio (Components) Ltd. ... 677 

714 

755 
676 

... 757 
660, 677 
... 704 

... 674 

... 755 

... 757 

... 754 

...657-9 
... 674 
... 666 

... 668 

... 704 
... 754 
... 701 
...cov. ii 

... 757 
... 756 



I.C.S 

International Correspondence Schools 
Ivorynt 

Jef Electronics 

Jermyn Industries 

Johnsons (Radio) Ltd 

K.V.A. Electronics 

Kensington Supplies 

Keytronics 

King. J. M. 

Lasky's Radio Ltd. 

Linear Products Ltd 

Lewis Radio 

London Computer Operators 
Training Centre 

M & B Components (Leeds) Ltd. 
Marktyme (Mail Order) Ltd. ... 

Marshall, A. Son 

Multicore Solders Ltd 

Nicholls, E. R 

NIP Electronics 



Oakfield Enterprises 

Padgetts Radio Store 

Partridge Electronics 

Personal Shoppers Plan Ltd. 
Premier Radio 

R.D.I. Ltd. 

Radio Components Specialists ... 
Radio Exchange Co. 
Radio Society of Great Britain ... 
R. & T.V. Components (Acton) Ltd. 

Readers Radio 

ROC Electronics Ltd 

R.C.S. Products 

RSC Hi-Fi Centres Ltd 

R.S.T 

SEBA Electronic Photography ... 
Service Trading Co. 
Salop Electronics ... 

Sinclair Radionics Ltd 

Shopertunities Ltd. 

Smith, G. W. & Co. (Radio) Ltd. 

Speakers Selection 

Stephens Electronics 

Stockton Partners 

Surplectronics 

Surplus Electronic Trading 

Technical Trading 

Thacker. A. H 

Thornbury Trade Disposals 

Velco Electronics 

Vero Electronics Ltd 

West London Direct Supplies ... 
Wicks, D. T. & Co 

York Electronics 

Z & I Aero Services Ltd. 



... 755 

... 696 

... 756 

... 750 

... 691 

... 754 

... 727 

... 703 

... 696 
... 752-3 

... 662 
...664-5 

... 692 
...670-3 

... 759 

... 732 

... 692 

... 754 
739-742 

... 681 
...747-9 

... 666 

... 751 

... 692 

... 662 

... 746 

... 735 

... 746 

... 756 

... 676 

... 662 

... 674 

... 680 

... 732 

... 760 



759 



Head Office and Warehouse 
44A WESTBOURNE GROVE 
LONDON W2 
Tel: 727 5641/2/3 



Z & I AERO SERVICES LTD. 

Please tend all correspondence and Mail-Orders to Heitd Office 

When sending cash with order, please include I2£np in £ for postage and handling 

MINIMUM CHARGE I5np. No C.O.D. orders accepted 

Please note that the valves offered below are not necessarily of U.K. origin 



Retail Shop 

85 TOTTENHAM COURT ROAD 

LONDON Wl 

Tel: 580 8403 

Open all day Saturday 



OA2 
OA3 
OB2 
OB3 
OC3 
OD3 



0.38 
0.45 
0.35 
0.70 
0.38 
0.35 



1B3GT 0.40 
1L4 ,0.20 



1R4 

1B5 

184 

185 

1T4 

1U4 

1C6 

1V2 

1X2B 

2A3 



0.45 
0.40 
0.30 
0.30 
0.30 
0.80 
0.80 
0.50 
0.50 
0.50 



2CW4 0.70 
2D21 0.88 



3A4 
3BP1 
394 
3V4 



0.40 
8.00 
0.35 
0.48 



6K4GY 0.76 
5U4G 0.36 
6V4G 0.45 
6Y3GT 0.40 
5Z3 0.60 
5Z4G 0.40 
6/30L2 0.80 
6AB4 0.36 
6AF4A 0.55 
6AG5 0.28 



6AQ5 0.38 
6AQ6 0.85 
6AR5 0.46 
6AR6 0.66 
6AK11 1.25 
6AS5 0.45 
6A87G 0.88 
6AT6 0.88 
6AU6 04S6 
6AV6 0.30 
6AW8A0.60'. 
6AX4GTB | 

o.eo 

8AW8A0.60 
6BA6 0.26 



6EA8 0.60 

6EH7 0.80 

6EJ7 0.88 

6EW6 0.70 

6F1 0.76 



6BF.6 
6BF5 
6BF6 



0.30 
1.00 
0.55 



6F5 

6F6G 

6F11 

6F18 

6F14 

6F15 

GF18 

6F23 

6F24 

6F25 

6F26 

6F28 



0.75 
0.86 
0.40 
0.46 
0.70 
0.86 
0.50 
0.85 
0.75 
1.00 
0.36 
0.65 



6X4 0.86 

8X5GT 0.40 

6X8 0.60 

6Y6G 0.70 

7Y4 0.66 

9BW6 0.60 

10C2 0.60 



10D1 
10D2 
10F1 
10F9 



0.68 
0.60 
0.76 
0.60 



6BH6 0.76 1 
6BJ6 0.60 1 



0BN6 
6BQ5 
6BB8 
6B87 



0.45 
0.26 
0.70 
1.80 



0.25 
0.40 
0.33 



6AG7 


0.40 


6AH6 


0.50 


6AJ8 


0.30 


8AKB 


0.35 


6AK6 


0.60 


6AL3 


0.43 



6AL5 0.20 
6AM5 0.35 



6BW6 0.85 

6BW7 0.80 
6BX6 
6BZ6 
6C4 

6C5GT 0.40 

6CB6 0.86 
6CD6GA1.85 

6CG7 0.68 

6CH6 0.60 

6CL6 0.68 

8CW4 0.66 

6CY5 0.48 



6CY7 

6D3 

6DC6 



0.70 
0.80 
0.80 



6DK6 0.80 
6DQ6B 0.70 
6D84 0.76 



6GK6 0.60 
6J4 0.60 
6J5GT 0.80 
6J6 0.20 
6J7 0.46 
6K6GT 0.60 
6K7 0.86 
0K8G 0.40 
6X96 0.76 
6L6GT 0.46 
6L7 0.40 
6L18 0.45 
6LD20 O.SO 
6N7GT 0.46 
6P1 0.60 



6P28 

6Q7 

6SA7 

6SG7 

68K7 



0.65 
0.40 
0.40 
0.40 
0.40 



6SL7GT0.86 
6SS7GT0.85 
6SQ.7 0.40 
68R7 0.40 
6T8 0.36 
6U4GT 0.65 
6U8A 0.40 
6V6GT 0.40 



10F18 0.60 
Hi Li 0.60 
10LD110.66 
10P1.1 0.60 
10P14 1.10 
12AB5 0.70 
12AC6 0.60 
12AD6 0.6S 
12AE6 0.66 
12AL6 0.60 
12AQ5 0.60 
12AT6 0.80 
12AT7 0.88 
12AU6 0.86 
12AU7 0.80 
12AV6 0.40 
12AV7 0.68 
12AX7 0.80 
12AY7 0.75 
12B4A 0.60 
12BAB 0.40 
12BA7 0.40 
12BE6 0.40 
12BH7 0.46 
12BY7 0.60 
12K5 0.70 
12K7GT0.40 
12Q7GT0.40 
19RR7 0.40 
20D1 0.60 



20L1 
20P1 
20P4 
20P5 



1.10 
0.80 
1.10 
1.20 



First Quality Fully Guaranteed 

<*'*'- BRAND 

: VALVES 




EP98 0.68 

EF183 0.80 

EF184 0.86 

EF800 1.00 

EK90 0.80 



20C8 0.60 
28L8GT0.60 
26Z4G 0.80 
S5Z6GT0.66 
30AC 0.50 
30AE3 0.40 
S0C1 0.80 



30C10 
30C17 
30C18 
30F5 



0.80 
0.90 
0.80 
0.86 



30FL1 0.76 
30FL12 1.20 
30FL14 0.86 
30L1 0.40 
30L15 0.86 
30L17 0.80 
30 PI 2 0.80 
30P19 0.86 
30PL1 0.76 
30PL13 0.98 
30PL14 0.00 
35A3 0.56 



80A0 0.76 
SOBS 0.60 
50C8 0.60 
60CDBG1.80 
60L6GT0.65 
8SA2 0.60 



3SAB 
36 BS 
3SC5 
38 Do 



0.78 
0.66 
0.60 
0.76 



36L8GT0.80 
33W4 0.86 
3SZ3 0.70 
3SZ4Q 0.86 
3SZ6GT0.60 



90AO 

90AV 

90C1 

90CV 

807 

818 

866A 

6642 

6080 

6146 

8360 

6939 

7199 

7360 

7886 

7895 

9002 

9003 

AZ1 

AZ31 

CBL1 



2.40 
2.60 
0.66 
2.40 
0.60 
3.76 
0.78 
0.70 
1.60 
1.60 
1.28 
2.26 
0.80 
2.00 
1.28 
1.26 
0.40 
0.60 
0.66 
0.66 
0.90 



hk'.i'j 0.66 

DL96 0.46 

DMlfiO 0.66 

DY88 0.82 

DY87 0.88 

DY802 0.88 

E8BtX 0.86 

E180F 1.00 

E810F 2.80 
EABC800.86 

EAF42 0.56 

EBC33 0.60 

EBC41 0.68 

EBC81 0.80 

EBF80 0.40 

EBF83 0.40 

EBF89 0.80 

ECS3 0.60 



BON 

EC88 
EC90 
EC91 
EC92 
EC93 



0.60 
0.60 
0.38 
0.80 
0.86 
0.66 



CBL31 1.00 
CY31 0.86 
DAF98 0.46 
DF96 0.46 
DK40 0.60 



EC8010 2.26 
ECC40 0.66 
I ;'■<■■• I 0.86 
ECC82 0.80 
ECC83 0.S0 
KCC84 0.30 
ECC85 0.40 
ECC88 0.40 



KCC89 0.60 
B0081 0.20 
ECC189 0.86 
ECF80 0.36 
EOF82 0.86 
ECF86 0.66 
ECF8041.66 
ECH42 0.76 
ECH81 0.80 
EOHB3 0.46 
ECH84 0.45 
ECL80 0.46 
ECL81 0.60 
ECL82 0.36 
ECL83 0.70 
ECL84 0.66 
ECL85 0.66 
K< 'l. ■'■ 0.40 
ECLL800 

1.66 



EF40 
EF41 
EF42 
EF60 
EF83 
EF86 
EF86 
EF89 
EF91 
EF92 
EF96 
EF97 



0.60 
0.66 
0.70 
0.25 
0.65 
0.85 
0.30 
0.28 
0.38 
0.35 
0.3S 
0.65 



EL33 
EI.34 
EL36 
EL87 
EL41 
EL42 
EL81 
EL83 
EL84 
EI.85 
EL86 
EL90 
EL95 



1.25 
0.50 
0.60 
1.60 
0.60 
0.65 
0.66 
0.42 
0.28 
0.48 
0.40 
0.38 
0.35 



EL821 0.80 

EL822 1.80 

ELL80 0.76 

EM34 1.00 

EM71 0.80 

EM80 0.46 

EM81 0.60 

EM84 0.86 

EM8B 1.00 

EH87 0.70 

EN91 0.88 

EYB1 0.40 

EY80 0.66 

EY81 0.40 

EY83 0.65 

EY86 0.40 

EY87 0.48 

EY88 0.43 



EZ40 
EZ41 
EZ80 
EZ81 



O.SO 
0.60 
0.27 
0.29 



GY601 0.80 

GZ30 0.40 

GZ31 0.88 

GZ32 0.48 

GZ33 0.70 



GZ34 0.60 
HABCS00.45 
HK90 0.40 
KT66 2.05 
KT88 8.00 
N78 1.60 
PABC800.40 
PC86 0.60 
PC88 0.60 
PC97 0.60 
PC900 0.48 
PABC800-40 
PCC84 0.40 
PCC85 0.40 
PCC88 0.55 
PCC89 0.65 
PCC189 0.56 
PCC805 0.86 
PCC806 0.80 
PCF80 0.80 
"CF82 0.86 
PCF84 0.80 
PCF86 0.60 
PCF87 0.90 
PCF801 0.60 
PCF802 0.60 
PCF805 0.80 
PCF806 0.70 
PCF808 0.85 
PCH2000.70 
PCL81 0.50 
PCL82 0.35 
PCL83 0.66 
PCL84 0.46 
PCL85 0.40 
PCL86 0.4S 
PCL88 0.80 
PCL800 0.98 
PCL801 0.76 
PD500 1.30 
PF86 0.65 
PF818 0.86 
PFL2000.66 
PL33 0.85 
PL36 0.55 



PL81 0.60 

PL83 0.45 

PL83 0.46 

FL84 0.40 

PL302 0.86 

PLS04 0.80 

PL508 0.90 

PLS09 Ufl 

PL801 0.80 

PL802 0-96 

PM34 0.60 



PYS1 
PY33 
PY80 
PY81 
PY82 
PY83 
PY88 



0.30 
0.63 
0.40 
0.80 
0.86 
0.38 
0.40 



U282 
U301 
U403 
U404 
U801 



0.40 
0.40 
0.60 
0.60 
0.80 



PY500 1.00 
PY800 0.40 
PY801 0.80 
PZ30 0.88 
QQV02-6 

2.88 
QQVO3-10 

U» 
QQV03-20A 

5.25 
QQV06-40 A 

6.60 
TT21 8.00 
TT22 8.80 
TY2-125 

10.00 
U18/20 0.76 
U26 0.80 



U26 

U31 

U37 

U62 

U76 

U78 

U191 

U201 

U281 



0.80 
0.60 
2.10 
0.35 
0.85 
0.36 
0.76 
0.86 
0.40 



UABC80 

0.40 
UAF41 0.60 
UAF42 0.66 
UB41 0-60 
UBC41 0.60 
UBC81 0.48- 
UBF80 0.4O 
VBF89 0.85 
CBL1 0.60 
UBL21 0.66 
UC92 0.40 
UCC88 0.40 
UCF80 0.66 
UCH21 0.60 
UCH42 0.70 
UCH81 0.40 
UCL81 0.60 
UCL82 0.86 
UC1.83 0.60 
UF9 0-80 
UF11 0-60 



UF41 
UF49 
UF43 
UF80 
UF85 
UF89 
UL41 
UL84 
UM84 
UU8 



0.80 
0.60 
0.60 
0.86 
0.40 
0.40 
0.65 
0.40 
0.26 
0.60 



T7Y1N 0.50 

TJY11 1.00 

UY41 0.48 

tnrsa o.so 

UY88 0.40 

W729 0.76 

Z7S9 8.00 

Z803U 1.20 



TRANSISTORS 



2N696 

2N697 

2N6S8 

2N705 

2N706 

2N708 

2N7S3 

2N929 

2N930 

2N987 

2N1131 

2N1132 

2N1184 

2N1301 

251302 

2N1304 

2X1305 

2N1306 

2N1307 

2N1308 

2K1309 

2N1613 

2N1711 

2N17S6 

2N2J47 

2N2160 

2H2217 

2N2218 

2N2219 

2N2369A 

2N2477 

2N2646 

2N2905 

2N292S 

2N2924 

2N2926 

2N3053 

2N3054 

2N3055 

2N3133 

2N3134 

2N3391 

2N3392 

2N3393 

2N3394 

2N3395 

2N3402 

2N3403 

2N3404 

2N3414 

2N3415 

2N3416 

2N3417 

2N3702 

2N3703 

2N3704 

2N3707 

2N3709 

2N3710 

2X3819 

2N3908 

28702 

28746 

ACU3 

AC125 

AC126 



0.17 
0.17 
0.30 
0.70 
0.10 
0.15 
0.26 
0.22 
0.25 
0.30 
0.25 
0.25 
1.86 
0.40 
0.75 
0.25 
0.25 
0.25 
0.80 
0.25 
0.30 
0.28 
0.26 
0.75 
0.76 
0.66 
0.30 
0.30 
0.85 
0.20 
0.85 
0.60 
0.85 
0.16 
0.15 
0.125 
0.26 
0.60 
0.76 
0.80 
0.80 
0.20 
0.15 
0.15 
0.15 
0.20 
0.15 
0.15 
0.85 
0.20 
0.15 
0.25 
0.25 
0.18 
0.12 
0.17 
0.15 
0.18 
0.12 
0.35 
0.20 
0.50 
0.2b 
0.15 
0.30 
0.20 



AC127 
AC128 
AC132 
AC1S3 
AC154 
AC167 
AC169 
AC176 
AC187 
AC188 
ACY17 
ACY18 
ACY19 
ACY20 
ACY21 
ACY22 
AD140 
AD149 
AD161 
AD162 
ADZ11 
ADZ 12 
AF114 
AF115 
AF116 
AF117 
AF118 
AF125 
AF127 
AF180 
AF181 
AF186 
AF239 
AFZ11 
ASY26 
A8Y27 
A8Y28 
ASY29 
ASY54 
ASZ1S 
A9Z16 
ASZ17 
ASZ18 
A8Z20 
A8Z21 
BC107 
BC108 
BC109 
BC113 
BC118 
BC134 
BC147 
BC148 
BC149 
BC162 
BC158 
BC176 
BC186 
BCYS0 
BCY31 
BCY33 
BCY34 
BCY72 
BCZ10 
BCZ11 
BD121 



0.20 
0.15 
0.86 
0.20 
0.15 
0.20 
0.10 
0.25 
0.30 
0.30 
0.878 
0.20 
0.86 
0.80 
0.80 
0.16 
41.60 
0.60 
0.65 
0.88 
1.85 
1.25 
0.20 
0.20 
0.20 
0.20 
0.46 
0.86 
0.80 
0.86 
0.35 
0.40 
0.40 
0.45 
0.86 
0.80 
0.86 
0.30 
0.26 
0.70 
0.70 
0.76 
0.76 
0.28 
0.40 
0.128 
0.12S 
0.125 
0.25 
0.30 
0.30 
0.176 
0.16 
0.15 
0.15 
0.16 
0.20 
0.25 
0.25 
0.40 
0.25 
0.80 
0.20 
0.80 
0.40 
0.85 



BD123 

BD131 

BD132 

BF11S 

BF167 

BF173 

BF179 

BF180 

BF181 

BF184 

BF185 

BF194 

BF193 

BF196 

BF197 

BF200 

BFW87 

BFW88 

BFW89 

BFW91 

BFX88 

BFY17 

BFY19 

BFYB0 

BFYS1 

BFYB2 

B8Y26 

BSY27 

B8Y28 

B8Y86 

B8Y95A 

OC16 

OC22 

OC23 

OC24 

OC25 

OC28 

OC28 

OC29 

OC30 

OC36 

OC36 

OC42 

OC44 

OC45 

OC70 

OC71 

OC72 

OC73 

OC75 

OC78 

OC78 

OC78D 

OC81 

OC81D 

OC83 

OC139 

OC140 

OC141 

OC170 

OC171 

OC200 

OC202 



0.80 
0.86 
0.86 
0.20 
0.18 
0.20 
0.80 
0.86 
0.26 
0.26 
0.20 
0.15 
0.16 
0.20 
0.20 
0.S5 
0.26 
0.23 
0.20 
0.20 
0.26 
0.40 
0.60 
0.25 
0.20 
0.25 
0.20 
0.20 
0.20 
0.20 
0.16 
0.60 
0.50 
0.60 
0.60 
0.86 
0.26 
0.60 
0.60 
0.76 
O.SO 
0.60 
0.20 
0.20 
0.16 
0.10 
0.18 
0.25 
0.80 
0.20 
0.20 
0.28 
0.20 
0.26 
0.16 
0.20 
0.30 
0.36 
0.80 
0.26 
0.26 
0.30 
0.65 



SYNCHROSCOPE TYPE C1-5 




3-in tube fltted with telescopic viewing hood, giving 
bright display in hill daylight. Sensitivity lOmV/mm 
(narrow band) to SOmV/mm (wide band). 
Bandwidth 10 c/s — 10 inc/s. Triggered sweep pre-set at 
1-2-5-10-30-100-300-1000-3000 ^ec per stroke. Free- 
running time base 20 c/s to 2000ko/s with built-in 
crystal calibrator providing timing marks at .05-.2-1-5- 
20-100 n sec +6%. 

Amptltude calibrator directly calibrated in volts. 
Input attenuator 1-10-100. 
Power supplies 127/230v AC. 

PRICE £89.00. Packing anil carriage 1.B0 

INTEGRATED CIRCUITS 

TAA263 Direct coupled 3-ntoge amplifier up to 
600ko. Supply voltage 6-8V output lOmW 
T072 outline 0-75 

TAA293. Medium frequency amplifier up to OOOkc. 
Supply voltage 0V. output lOmW T074 
outline . . . . 0-95 

TAA320. MOST stage followed by a bi-polar stage 
Gate-to-snurce voltage 9-14V. Power dis- 
sipation 200m W. TO l s outline . . 85 

TAA570. Four-stage llmiter-ampllfler with P.M. 
quadrator detector and remote D.C. volume 
oontrol facility. Nominal supply voltage 
12V. T074 outline 95 

TAD100. AM receiver circuit containing all 
active components (except output stage) 
required to build a complete receiver . . £1-98 

PHOTO- EMISSIVE DBVICE8 

GA8 Light emitting dloae type MV10B . . 41 OS 

Photo-translBtor OCP71 0-90 

Photo-conductive cell ORP18 0-60 

Photo-conductive cell ORP80 0-60 

Photo-conductive cell ORP81 0-88 

Photo conductive cell ORP90 110 

Photo-conductive cell ORP91 1-10 

GAS Photocells 90AQ 2 40 

90CG 8 40 

Vacuum Photocells 90AV 2-60 

90CV 2 40 



TWO NEW MULTIMETERS 
FROM RUSSIA 



Type U43I2 
1143 1 3 

wiifc AC current ranges 

Typ» 134312 — Low sensi- 
tivity iBstrument (667 
o.p.v.) 1% accuracy, on 
.)(: » nd 1 -5 % on AC. 9 current ranges on DC (SOOjjA to 6A) 
iind 8 current ranges on AC (1 -5mA to 6A). 9 voltage ranges 
11-3 to 900V AC/DC. Resistance 0-2 to 30k Q. Mirror scale. 

i'RICE, complete with leads and steel carrying case £9.76 

Type U4818— 20.000 cp.v. DC and 2,000 o.p.v. on AC. 
II DC current ranges SOyA to 10 A. 6 AC current ranges 
n-6 to 1-SA. 9 DC and AC voltage ranges 1 -S-SOOV. Resisl- 
luice ranges 0-5-BOOkQ. Accuracy 1-5% DC and 2-5% AC. 
Mirror scale. 
;*RICE, complete with test leads and steel carrying case 

210.80 





AC/DC MULTIMETER AND 
TRANSISTOR TESTER 
8-DC voltage ranges 0-3-900V 
6-AC voltage ranges 1.6-760V 
5-DC current ranges 006-fl00mA 
4-AC current ranges 0-3-300mA 
4-resistance ranges 0-6-fiOO Kobms 
Translator cut-off current 60/jA max 
Transistor DC current gain 10-300 
Sensitivity: 16700 £3/V DC; 
3300 fi/V AC 

PRICE U0-6O 



H 



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COMPLETELY NEW 
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CATALOGUE 




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TEST EQUIPMENT FOR 
EVERY PURPOSE 

AFI05 50k/V multimeter (iilus.). 

Price £8-50, p.p. 20p. Leather case 

200H 20k /V. 

Price £3-87, p.p. 20p. Case 62p. 

500 30k/V multimeter. 

Price £8 -87, p.p. 20p. Leather case 

THL33 2k/V. 

Price £4-12, p.p. I5p. Leather case 

TE65 Valve voltmeter 

Price £17-50, p.p. 40p. 

SE250B Pocket pencil signal 

injector. Price £1 -75, p.p. 

ISp. 
SE500 Pocket pencil signal tracer. Price £1-50, 
p.p. I5p. 

TE20D RF generator. Price £15. p.p. 40p. 
TE22D Matching audio generator. Price £17, 
p.p. 40p. 

TEI5 Grid dip meter. Price £12-50, p.p. 40p. 
T03 Scope 3 in. tube. Price £37-50, p.p. 50p. 
TE22 Audio Generator. Price £17, p.p. 40p. 
CI-5 Pulse Scope. £39 00. p.p. 50p. 

PANEL METERS 

Complete range in stock. 38, 65 and 85 types plus large 
Edge types also 240°-250° types. 

(Get a copy of our latest catalogue for full specification 
further ranges.) 




MomcFBtammMtm 

PRICES ALWAYS FROM HENW'S 

• COMPONENTS IN STOCK FOR ALMOST ALL 
PUBLISHED DESIGNS. YOUR ENQUIRIES INVITED. 
SEND LARGE S.A.E. (WITH LIST) FOR PARTS QUOTE 
FOR ALL CIRCUITS. 

SEE OUR ADVERTISEMENT INSIDE THIS MAGAZINE 
FOR THE LARGEST RANGE OF TRANSISTORS AND 

I.C's. ETC. AVAILABLE IN U.K FREE LIST No. 36 

ON REQUEST. 

HENRY'S SUPPLY ALL YOUR 
AUDIO-ELECTRONIC NEEDS ! 



Electronic Components. I High Fidelity Sales & 

Audio and Test Gear Centre \ Demonstrations Centre 



TRANSISTOR AMPLIFIERS 




(Leaflets Ref. No. 6 and 8) 
Post, etc. 20p. 

4-300 4TR 9V 300mW £1-75 PA7 5TR 16V 7W £3-62 

104 4TR 9V IW £2-12 608 6TR 24V I0W £4-12 

304 4TR 9V 3W £2-47 410 4TR 28V I0W £4-97 

555 6TR 12V 3W £2-75 MPAI2/3 6TR 18V I2W £4-50 

MPAI2/I5 6TR 36V I2W £5-25 
OPTIONAL POWER SUPPLIES Poit, etc. 20p 

P500 (I or 2) for 104, 304 £2-62 

PS20 (I or 2) for PA7 £J-47 

MU24/40 (I or 2) for MPAI2/3 or MI'AI2/I5 £4-50 

PI I for 608 £2-87 PI5 for 410 £2-62 




SINCLAIR 
PROJECT 60 
PACKAGE 
DEALS— SAVE 
POUNDS ! 

2xZ30 amplifier, stereo 60 pre-amp, PZ5 power supply, £16-75. 
Carr. 40p. Or with PZ6 power supply £18-25. Carr. 40p, 
2xZ50 amplifier, stereo 60 pre-amp, PZ8 power supply £20-25 
Carr. 40p. Transformer for PZ8 £2-45 extra. Any of the above 
with Active Filter unit add £4-75 or with pair QI6 speakers 
add £16. Also new FM Tuner £21. 2000 Amplifier £24-50, p.p. 
SOp. 3000 Amplifier £31 -50, p.p. 50p. Also ICI2 £2-50. 



LOW COST HI-FI SPEAKERS 

E.M.I. Size 1 3 J- x BJ- 
TYPE 150 6 watt. .1, 8 or 15 

ohms £2-12. Post 22p. 
TYPE I50TC Twin cone ver- 
sion £2 -75. Post 12p. 
TYPE 450 10 watt with twin 
tweeters and cros;.over. 3, 8 
or 15 ohms. £3-50 Post 25p. 
TYPE 350 20 watt wi:h tweeter 
and crossover. 8 and 15 ohms. 
£7 -50. Post 28p. 
POLISHED CABINETS For 150. I50TC and 450 £4-50. 
Post 30p. TERRIFIC RANGE OF SPEAKERS. KITS AND 
CABINETS IN STOCK— SEE CATALOGUE OR YOUR 
ENQUIRIES INVITED. 





HI-FI TO SUIT 
EVERY 
I POCKET 




TELETON *206', Garrard 
SP25 Mk.111, Goldring G800 
Series Cart., Plinth/Cover. 
10 watt 3 way bookshelf 
Speaker Systems. All leads 
etc. (Rec. Price £81). 

& VE £54-95 §* 

or with HL. Sayoy (U.K. 

made) same performance 

£5695 

PLUS 

FREE PAIR STEREO 

HEADPHONES 

TELETON F2000, Med. 
Wave, Stereo FM Tuner 
Amplifier, Garrard 2025TC. 
9TAHC Diam., Plinth/ 
Cover, 10 watt Speaker 
Systems as above, all leads 
etc. (Rec. Price £91). 

%?* £59-95 "if- 

PLUS 

FREE PAIR STEREO 

HEADPHONES 

THE TWO MOST POPU- 
LAR SYSTEMS EVER — 
PLUS FULL 12 MONTHS- 
GUARANTEE AS WITH 
ALL "HENRY'S" OFFERSI 

FRCP 10 page Audio- 
n c c Hi Fi Stock and 
Stereo Systems Discounts 
Lists. Save up to 40% I 
Demonstrations and Credit 
Terms (to callers) plus 12 



MONO, STEREO AND 
Ml XI NG EQUIP- 
MENT. HIGH QUAL- 
ITY WITH LOW 

PRICES. 




FET 9/4 Mono or single channel. 
Adjustable levels. All facilities plus 
microphone. Mixing. Price £12-50 
FET 154 Stereo with all facilities, 
magnetic cart, input etc.' Price 
£16-50 

SILICON POWER AMPLI- 
FIERS FOR USE WITH ABOVE 
PA 25 25 watts into 8 ohms £7-50 
PA 50 50 watts into 4 ohms £9-50 
MU442 Power Supply for I or 2 
PA25's or I only PA50 £6-00. 
Post 20p. 

FREE BROCHURE NO. 25 ON 
REQUEST. 

NO SOLDERING — ALL UNITS 
INTERCONNECTING. 
ON DEMONSTRATION AT "356" 



IIUILD THIS VHF FM TUNER 

J MULLARD TRANSISTORS 

300 kc/s. BAND-WIDTH. 

PRINTED CIRCUIT, HIGH 

FIDELITY REPRODUCTION. 

MONO AND STEREO. 

A popular VHF FM Tuner for 

quality and reception of mono 

and stereo. There is no doubt 

about it— VHF FM gives the 

F.EAL sound. All parts sold 

separately. 

Free Leaflet No. 3 & 7. 

TOTAL £6 97 p.p. 20p. Cabine 

Tuning meter £1-75 

Mains unit (optional) Model PS900 £2-47 

Mains unit for Tuner and Decoder PSI200 £2 62 




lOOp. Decoder Kit £5-97 



NEW "BANDSPREAD" PORTABLE TO BUILD 

Frinted circuit all transistor 
cesign using Mullard RF/IF 
Module. Medium and Long 
Wave bands plus Medium 
Wave Bandspread for extra 
selectivity. Also slow motion 
geared tuning. 600 mW push- 
pull output, fibre glass PVC 
covered cabinet, car aerial 
Attractive appearance and 
performance. 

TOTAL COST TO BUILD £7-98, p.p. 32p (Battery 22p). 
All parts sold separately — Leaflet No. 2. 
TV' PORTABLE (as previously advertised) £6-98, 
p.p. 35p from stock— Leaflet No. I. 




NIXIE TUBES 

XN3 or XNI3 0-9 side view 

with data sheet 85p each. 

GN4 End view 0-9 with 
socket and data £1-75. 

All I.C.-s for Digital Clocks in 
stock. HENRY'S CLOCK 
CIRCUIT No. 29/2, ISp. 



20 WATT I.C. AMPLIFIER 

Toshiba 20 watt Power Ampli- 
fier £4-57. 

Toshiba Pre-Amplifler I.C. 
£1 50. 

Data and suggested circuits 
No. 42, IOp. 

SL403D-3 watt I.C. Amp 
£1-50. Complete with data & 
circuits. 



LONDON, W.2. 
Tel : 01 -402 4736 



LONDON, W.2. 
Tel : 01 -402 5854 



FREE BROCHURES 

* P.A., DISCO, LIGHTING 
No. 18 

* ELECTRONIC ORGANS 
IN KIT FORM No. 9 

* HIGH FIDEUTY No. I6/I7 

* TRANSISTORS, I.C's No. 
36 

All details also in latest cata- 
logue — see above. 



Electronic Organs, I Mail Orders, Special Bargain 

P. A. & Discotheque Centre I Shop, Industrial Sales 



n * /:l ,1^ ;(tri»)W »:■!-:■ 3tTrtvM:<J ;'iTl »lBIBcdV«d iTr\ ','f.l - 



LONDON, W.2. 
Tel : 01 -723 6963 



LONDON, W.2. 
Tel: 01-723 1008/9 



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