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INTERACTIVE

ELEKTORELECTRON/CE

CONTENTSOctober 1994Volume 20Number 226ISSN 0268/4519

Apologies

We regret that, owing to circum-

stances beyond our control,

Part 20 of 'Figuring it Out'

(Using a computer) has had to

be postponed till next month.

In next month's issue

Single -wire

communicationDebugging the8031 seriesPhantom power supply(for guitars)Centronics buffer for

ISPLSI

Simple capacitance meterApplication note: Opticalwindow comparatorand others for yourcontinued interest.

Front coverIt appears that the in -car

audio system has overtakenspot/fog lights, spoilers andsport steering wheels as thecar status symbol of themid -1990s. In line with thattrend, here's our version of a200 W in -car audioamplifier. But to those whoare inclined to turn up thevolume too high a warning:do not, as many before you,ruin you hearing; it's notworth it!

Copyright ©1994 Elektuur

A B CAUDIT BUREAU OF CIRCULATIONS

CONSUMER PRESS

4 I '

28 Voice scramblers FX118 and PCD4440by G. Kleine

10 PROJECT: Integrated audio amplifier - Part 2Design by T. Giesberts

32 PROJECT: In -car audio amplifierDesign by T. Giesberts

S 11'

22 PROJECT: Computer PSU monitorDesign by K. Walraven

50 COURSE: PIC programming - Part 3By our editorial staff

42 Transformers: an overviewBy K. Schonhoff

5 PROJECT: Motive -battery chargerDesign by L. Lemmens

26 PROJECT: Stable d.c.-d.c. convertorDesign by L. Lemmens

18 PROJECT: Tester for infra -red remote controlDesign by A. Rietjens

56 PROJECT: TV line monitorDesign by J. Matus

Book availability & prices 73Buyers' guide 82Components Select 64Index of advertisers 82Readers' services 70Switchboard 73Terms of Business 72

Mini 1/0 card for Casio FX850/880PSince the legal arguments between the owner of the software

copyright and the author of the article have been resolved, thefloppy disk containing the program is now available again.

See page 31

Integrated AF amplifier - p. 10

Tester for infra -red remote controlunit - p. 18

4

Computer supply monitor - p. 22

TV line monitor - p. 56

Elektor Electronics is published monthly, except in August. by Elektor Electronics (Publishing), P.O. Box 1414, Dorchester, Dorset DT2 SYH. England. The magazine isavailable from newsagents, bookshops, and electronics retail outlets, or on subscription at an annual (1994/95) post paid price of 28.00 in the United Kingdom; air speeded:

£3500 in Europe, £44.00 in Africa, the Middle East and South America; £4600 in Australia, New Zealand and the Far East; and SUS 59.00 in the USA and Canada. SecondClass Postage paid at Rahwah N.J. Postmaster: please send address corrections to Elektor Electronics, c/o Mercury Airfreight International Inc., 2323 Randolph Avenue,Avenel, New Jersey, N.J. 07001.

ELEKTOR ELECTRONICS OCTOBER 1994

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MOTIVE -BATTERY CHARGERU

Design by L. Lemmens

The battery charger is intended primarily for charging, andkeeping charged, without supervision, lead -acid batteries ofcars and motorcycles that are laid up for lengthy periods,

for instance, during the winter.

If a verhicle is laid up for a lengthy pe-riod, it is advisable to keep its (lead -

acid) battery charged properly during thisperiod as this will extend its life consid-erably compared to leaving it just in thevehicle and charging it when the vehicleis needed again. Unfortunately, the bulkof vehicle battery chargers is not suitablefor unsupervised, continuous chargingfor long periods.

Self dischargeEven when a lead -acid battery is not inuse, its internal chemical action doesnot stop. Owing to small impurities inthe acid, there are always tiny currentloops in action, causing self discharge.In new batteries, this does not amountto much, just a few tenths of a per centper day. Some self discharge also re-sults from the electrochemical reactionbetween the lead dioxide of the positiveplate lattices and the lead alloy of thegrid. This is a form of corrosion, whichin a fully charged battery is negligible,but can take on alarming dimensionsin a neglected (discharged) battery. Ifthe battery becomes totally discharged,the damage may be irreversible. This isbecause the lead sulphate formed inthe plates during the dischargechanges in structure: relatively largecrystals of lead sulphate are formedwhich block the lattices in the plates.Both the negative and the positiveplates become entirely sulphated and,as they are now composed of identicalmaterial, the terminal voltage col-lapses. The battery is then a write-off.

Charging during layoffsThere is only one way of preventing abattery being destroyed through self -discharge and that is to keep it regu-larly charged. However, this should bedone in an intelligent way, becauseovercharging a lead -acid battery is justas bad for it as a complete discharge.This means that a charger is requiredthat does not just charge the battery,but also continuously monitors its con-dition and acts accordingly. Most com-mercial lead -acid battery chargers haveno such facility and are thus totally

unsuitable for keeping a batterycharged unsupervised.

Charging current & voltageThe state of charge of a lead -acid bat-tery is reflected by its cell voltage.Normally, this is 2 V. However, accu-rate measurements show that this volt-age seldom has its nominal value. Thecell voltage of a partly charged batterynot in use is 1.9-2.0 V, that of a fullycharged battery is 2.05-2.1 V. Thecharging voltage should be slightlyhigher, because during charging thecell voltage rises. In general, a batteryis fully charged when its cell voltagehas risen to 2.2-2.3 V (that is,13.2-13.8 for a 12 V battery). When thecell voltage reaches 2.35-2.4 V, there isa sharp rise in voltage. Most of thecharge is then used in dissociating thewater of the sulphuric acid solutioninto hydrogen and oxygen and the cellbegins to gas freely. It is thus advisableto treat 2.4 V as the upper limit of thecell voltage during charging.

There are three different ways ofcharging a battery: normal (the mostcommon), fast and trickle.

The charging current during nor-mal charging is one tenth to one twen-tieth of the nominal battery capacity inampere -hours (Ah). Thus, a 20 Ah bat-tery should be charged with a currentof 1-2 A.

Fast charging takes place with acurrent that is three to five times largerthan that used during normal charg-ing. The condition of the battery needsconstant monitoring, because the riskof overcharging is high. It is, in anycase, advisable to use fast chargingonly in exceptional cases. Repeatedfast charging reduces the useful life ofthe battery.

Trickle charging is not intended tocharge a battery, but rather to keep itin good working condition by counter-ing the effects of self discharge. Thecharging voltage should not be higherthan 2.2 V per cell and the chargingcurrent may be limited to 1/1000 to1/2000 of the battery capacity.

Which charging method?It is clear that for the present batterycharger fast charging is not a methodworth considering. Strictly speaking,trickle charging should do the trick.With proper design. a trickle chargercould be left charging the battery for awhole year. Unfortunately, a tricklecharger requires that from the onsetthe battery is fully charged. If the bat-tery is partly discharged when it is laidup, a trickle charger would not be ableto charge it in a year.

Therefore, the present charger usesa combination of normal charging andtrickle charging. It is, in fact, a stan-dard charger provided with voltage andcurrent monitoring facilities. Thecharging current is 0.5 A: it can notrise above that level because of the in-ternal protection circuits.

Since the charger also contains pre-set voltage limiting, the cell voltage ofthe battery on charge can not exceed acertain level. When, for instance, thepreset voltage of 2.2 V is exceeded, thecharging current is interrupted. When

Fig. 1. Circuit diagram of the motive -battery charger.


6

after a while the voltage has droppedbelow 2.2 V, the charging current isswitched on again.

Circuit descriptionThe mains voltage enters via K1 (seeFig. 1) and the output (charging) volt-age is available at K2. The mains volt-age from K1 is applied to a bridge recti-fier, D2 -D5, via transformer Tr1. DiodeD6 serves as on/off indicator; C3 is abuffer capacitor, and C2 decouples anyr.f. noise voltage.

O0

The heart of the circuit is a TypeL200, IC1, from SGS Thomson. It is aprogrammable voltage and current reg-ulator, housed in a five -pin case, whichis reputed to be virtually indestruc-tible. It can handle input voltages up to40 V, with peaks up to 60 V, provides acurrent of up to 1.8 A, and is furnishedwith reliable thermal and short-circuitprotection.

The L200 is a general-purpose chip,which in the present circuit is used asa current source that is switched off ifthe output (that is, charging) voltage

0 0

0 0

Fig. 2. Printed -circuit board for the motive -battery charger

Fig. 3. Finished prototype board.

exceeds a certain value. This is done bycomparing this voltage continuouslywith the 2.77 V reference potential atpin 4. The switch -off value is set withP1.

The peak output (charging) currentis set by R1. When the current limitingis actuated, the voltage across R1, ac-cording to the manufacturer, is about0.45 V, which gives a charging currentof 450 mA.

Schottky diode D1 prevents the bat-tery discharging through IC1 if there isa mains failure. In that case, the cur-rent is limited to that through R3, R4and P1, which amounts to only 3.5 mA.

Resistor R2 protects ICI against thebattery being connected with incorrectpolarity. This is, however, only a short-term protection; if the battery remainsconnected with incorrect polarity, bothIC1 and C4 will give up the ghost.

ConstructionThe entire circuit, including the mainstransformer, is intended to be built onthe printed -circuit board in Fig. 2.Finishing the board is straightforward.

Note that a large space has been re-served on the board for a heat sink forIC1, because this chip will dissipateabout 3 W. The IC must be electricallyinsulated from the heat sink with a ce-ramic washer and heat transfer paste.

When the board has been finished(see Fig. 3), it should be fitted in awell -insulated synthetic fibre case.

AlignmentTo set P1 to the required voltage limits,a 12V battery and two multimeters areneeded-see Fig. 4.

Connect the charger to the mainsand switch it on.Connect the battery to the output ofthe charger, with one of the multi -meters (set to lA d.c. range) in se-ries with the + output terminal.Connect the other multimeter (set to25 V range) across the output of thecharger.Adjust P1 for maximum output volt-age.The battery is now being charged;observe the charging voltage.

When the charging voltage reachesthe desired maximum value, say,13.5 V, slowly turn P1 back untilthe charging current is zero.

If a laboratory power supply unit(PSU) is available, it may be used tosimulate a battery by connecting a27 S-2, 5 W resistor across its outputterminals. Set the PSU output to13.5 V, connect it to the output of thecharger and adjust P1 till the currentjust drops to zero.

In a rare case, it may happen thatthe required voltage limits can not be


UProduced and published by ELEKTOR TICEHURST TN5 7HE GERMANY NETHERLANDS

ELECTRONICS (Publishing) Telephone: (0580) 200 657 (National ) Elektot Verlag GmbH Elektuur BV

or +44 580 200 657 (Intel national) Susterfeld Stralk 25 Peter Treckpoelstraat 2-4

Editor: Len Seymour Fax: (0580) 200 616 (National) 5100 AACHEN 6191 VK BEEK

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Telephone: (0305) 250 995 (Nationqi)or +44 305 250 995 (International)

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or +44 305 250 996 (International) Director: M M J Landman Elektot Elektromkai folyOrat Ferreira & Bento Lila.

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set with P1. This may be because theinternal reference potential of the IC isslightly too high. This may be remediedby lowering the value of R4 slightly (to,say, 2.2 kS2).

FinallyDiode D6 may be fitted outside the en-closure and be connected to the boardvia two lengths of flexible, insulatedcircuit wire.

Use flexible, insulated wire of dia.0.75 mm for the connections between

the battery and K2. Use red wire for the+ve line and green or black wire for the-ye line. Suitable clamps can be ob-tained from car parts dealers or goodhardware shops.

When disconnecting the battery, al-ways take off the negative cable firstand then the positive one. When con-necting the battery, put on the positivecable first and then the negative one.These precautions will prevent a shortcircuit of the battery if the positivecable terminal accidentally touches theframe of the car or motorcycle.

Parts list

Resistors:Ri = 1 QR2 = 150 S2R3 = 1 kS2R4= 2.2 kS2 - see textR5 = 1.5 kQP1 = 1 kS2 multiturn preset

Capacitors:CI, C2 = 100 nFC3 = 220 pF, 40 V, radialC4 = 22 pF, 25 V, radial

Semiconductors:D1 = BYW29- 100D2 -D5 = 1N4001D6 = LED, red, 5 mm

Integrated circuits:ICI = L200CV (5 -pin)

Miscellaneous:Ki = 2 -way terminal block, pitch

7.5mmK2 = 2 -way terminal block, pitch

5 mmTri = short -circuit -proof mains

transformer, 15 V, 13 VAEnclosure, synthetic fibre

120x65x65 mm (43/4x21/2x21/2 in)Heat sink 5 K W-1, complete with

fitting/insulating kitPCB Ref. 940083

[940083)

Fig. 4. During alignment, both voltage and current must be monitored.



CC

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POWER SUPPLIESASTEC AC9232-01 Switch mode PSU 50 watts input 230V 0.6A 50-60hz outputs +12V 2.5A, +5V6.0A, ± 5V 0.5A, ± I 2V 0.5A, E17.80 EachSOLAR CELL 2 volt 150mA max, size 60 x 100mm 41.35 each 5 for L6.00BNC SOCKETS 50 ohm single hole fixing 50p each 10 for £4.00MULTITURN PRESETS 20mm RECT, I K, 5K, 10K, 20K, 50K, 100K, I MO 40p each, 3 for {1.00

MINIATURETOGGLE SWITCHESspdt 60p each spdt 3 position c/off 70p each

dpdt 70p each dpdt 3 position c/off 80p each

spdt biased 60p each spdt 3 position c/off biased both ways 70p each

dpdt 3 position c/off biased one way 80p each

MIN PUSH TO MAKE SWITCH 50p. MICRO SWITCH roller arm spdt 40p .

DIL RELAYS 5 volt dp/changeover 60p each 10 for 45.0012 volt dp/changeover 80p each 10 for £6.00

CAR HORN RELAY in metal can with fixing lug s/pole on 10 amp contacts E1.00 each 6 for £5.0020 AMP RELAY dp o 12 volt LI.50 each 4 for E5.00REED RELAY 12 vol 50p each 10 for C4.00

240 VOLT AC RELAY 3 -pole c/o 10amp contacts £1.50 each 4 for L.5.00

RECHARGEABLE BATTERIESAA (HPT) 600mAH E1.02 each C(HPII) I 200mAH £2.99 each

D(HP2) 1200MAH E2.40 each PP3 8.4V 100mAH £4.77 eachFLUORESCENT LIGHT INVERTOR Drives an 8 watt tube directlyfrom 6a, d.c. Data supplied. £4.50 each

BREADBOARDS173 X 65mm 840TP

E5.25 each9V D.C. CASSETTE

MOTOR40mm Dia 30 H

£1.00 each

6 FOR £5.00

BULK LEDSOFFER

SOO 5mm roundRED LEDS L25.85

E. 1.00 BARGAIN PACKSBO I 4 x SUB -MINIATURE TOGGLE SWITCHES S.Pole P.C.B. MountingB02 3 x SUB -MINIATURE TOGGLE SWITCHES D.Pole PC.B. Mounting803 3 x SUB -MINIATURE TOGGLE SWITCHES D. Pole 3 pos, centre off8004 3 x DILL SWITCHES 4 -way s.p. onBOOS 2 x DILL SWITCHES 8 -way s.p. onB006 2 x DILL SWITCHES 12 way 90' s.p. onB007 12 x PP3 BATTERY SNAPS0008 I x CAPACITOR I FARAD 5.5 VOLT 20mm dia. x 7mm high0009 5 x INSTRUMENT KNOBS (0.25" SHAFT) High quality grey plastic knob, collet fixing 15ram dia.

0010 3 x INSTRUMENT KNOBS (0.25" SHAFT) High quality grey plastic knob collet fixing 29mm dia.

13011 4 x MAGNETIC EAR -PIECE 8 ohm with 3.5mm plug13012 4 x 28 -WAY TURNED PIN DIL SOCKET0013 IS x 12 VOLT WIRE -ENDED LAMPSB015 2 x LIGHT DEPENDENT RESISTOR less than 200 ohms in day light, greater than 100

megohms in darkness

B016 I x KEYPAD 20 -key in 5 x 4 matrix bubble type switch contacts0017 2 x PIEZO BUZZERS approx 3 to 20 volt d.c.8018 5 x 78M12 VOLTAGE REGULATORS positive 12V SOOmA8019 4 x TLO82CP bi-fet op -amps0020 20 x ASSORTED LEDS full spec. various shapes and sizesB021 3 x INFRA -RED DIODE TX/RX PAIRS made by Honeywell (no info)B022 3 x CONSTANT CURRENT LED Smm round, red 2-I8V d.c.or a.c. nominal 14mA13023 SO x IN4 I 48 DIODEB024 2 x INFRA -RED TRANSISTORS FPT5I3313025 5 x DIACS13026 3 x BDX33C 10amp 100V npn transistorB027 12 x 2N3702 Transistor0028 12 x 2N3904 TransistorB029 12 x BC337 TransistorB030 4 x LM3I7T Variable regulator mounted on a small heatsink13031 2 x MAN6610 2 digit 0.6" 7 segment display Com anode, amber8032 3 x PHONO TO PHONO LEADS 63cm long8033 IS x RECTANGULAR RED LEDS 6 x 6 x tram stackable13034 I x PHOTO SENSITIVE SCR mounted on a PCB, data sheet supplied

B035 4 x IECPANEL MOUNTING MAINS PLUG Snap fixB036 5 x ASSORTED PIEZO TRANSDUCERS13037 S LENGTHS OF HEATSHRINK SLEEVING 8mm dia. 400mm long0038 25 x CERAMIC DISC CAPACITORS 0.1 mfd 63V8039 15 x MONOLITHIC CERAMIC CAPACITORS 0.1 rnfd 63V, in a dill package

0040 25 x ASSORTED ELECTROLYTIC CAPACITORS PCB mounting useful valuesB041 25 ASSORTED PRE-SET RESISTORSB042 6 x 3.5MM LINE JACK SOCKETS (mono)B043 6 x 3.5mm JACK PLUGS (mono)8044 8 x 3.5mm CHASSIS SOCKET (mono)B045 2 x TRIACS 800V 8 ampB046 12 x BC2I3L TransistorB047 12 x MIN SLIDE SWITCH dpdtB048 15 x MIN CERMET TRIMMER POTS (good range of values)5049 I x PCB WITH TWO LARGE LEDS 15mm square, one red one green13050 I x I2VDC RELAY 4 pole c/o with plug in baseB051 4 x LM324 quad op -amps8052 4 x 555 Timer0053 S x 741 op -ampB054 25 x IN4001 diode0055 20 x IN4007 diodeB056 I x SLOTTED OPTOB057 I x DAC08 digital to analogue convertor with dataB058 4 x OPTO ISOLATOR5060 3 x C106D THYRISTOR13061 5 x 78MO5 VOLTAGE REGULATORS positive S volt 500mAB062 10 x TACTILE SWITCHES5063 25 x 0.0IMFD 50V CERAMIC DISK CAPACITORS

PLEASE USE ORDER CODE WHEN ORDERING THE BARGAIN PACKS.

Please make cheques and postal orders payable to MAILTECHAll prices includeVAT.

Please add f1.00 postage and packing to all orders.Telephone enquiries between 10.00am and 3pm Tuesday to Thursday.

Fax and answerphone at other times on 058 474475.

: ,

A


Please mention ELEKTOR ELECTRONICS when contacting advertisers 9

POWER AMPLIFIER MODULES -TURNTABLES -DIMMERS -LOUDSPEAKERS -19 INCH STE

talt:Zsd*PB 4ILL1,14:11,A.:111.411; THOUSANDS PURCHASEDBY PROFESSIONAL USERS

THE RENOWNED MXF SERIES OF POWER AMPLIFIERSFOUR MODELS:- MXF200 (100W + 100W) MXF400 (200W + 200W)

MXF600 (300W + 300W) MXF900 (450W + 450W)ALL POWER RATINGS R.M.S. INTO 4 OHMS, BOTH CHANNELS DRIVEN

FEATURES: *Independent power supplies with two toroidal transformers * Twin L E D Vu meters *Level controls * Illuminated on/off switch * XLR connectors * Standard 775mV inputs * Open and short circuitproof * Latest Mos-Fets for stress free power delivery into virtually any load * High slew rate * Very lowdistortion * Aluminium cases * MXF600 8 MXF900 fan cooled with D C loudspeaker and thermal protection

USED THE WORLD OVER IN CLUBS, PUBS, CINEMAS, DISCOS ETC

SIZES:- MXF200 W19" 0.13'2" (2U)xD11"MXF400 WI 9"x1451," (3U)aD 1 2"MXF600 W19"x1151,4" (3U)::013"MXF900W19"xH5"." (3U)x1211 44"

PRICES:-MXF200 £175.00 MXF400 £233.85MXF600 C329.00 MXF900 C449 15SPECIALIST CARRIER DEL. 212.50 EACH

'41,`, I :217(03c1-.1 d 4 :141c35`.7 %WI** I VI 4 04 1:

Advanced 3 -Way Stereo Active Cross -Over, housed in a 19" x 1U case Each channel has three level controlsbass, mid 8 top. The removable front fascia allows access to the programmable DIL switches to adjust thecross -over frequency, Bass -Mid 250/500/800Hz, Mid -Top 1.8/3/5KHz, all at 24dB per octave Bass invert switcheson each bass channel. Nominal 775mV input/output. Fully compatible with OMP rack amplifier and modules

Price £1 17.44 + £5.00 P&P

L.114:4*11E-1.101,`,11:44:1-1141cES1/-1

- ' *

SERVICE LARGE (A4) SOp STAMPED FOR CATALOGUE

rAl,`,111H01-"Bd 11:./01714:ill:111IA I 4:1,',11.111114-4, SUPPLIED READY BUILT AND TESTED.

These modules now enjoy a world-wide reputation for quality, reliability and .performance at a realistic price. Fourmodels are available to suit the needs of the professional and hobby market i.e. Industry, Leisure, Instrumental and Hi-Fietc. When comparing prices. NOTE that all models include toroidal power supply. integral heat sink. glass fibre P.C.B. anddrive circuits to power a compatible Vu meter. An models are open and short circuit proof.

THOUSANDS OF MODULES PURCHASED BY PROFESSIONAL USERSOMP/MF 100 Mos-Fet Output power 110 wattsR.M.S. into 4 ohms, frequency response 1Hz - 100KHz-3dB, Damping Factor 300, Slew Rate 45V/uS,T.H.D. typical 0.002%, Input Sensitivity 500mV, S.N.R.-110 dB. Size 300 x 123 x 60mm.PRICE £40.85 - £3.50 P&P

= * ECHO & SOUND EFFECTS*STEREO DISCO MIXER with 2 a 7 bandL 8 R graphic equalisers with bar graphLED Vu meters. MANY OUTSTANDINGFEATURES:- including Echo with repeat &speed control, DJ Mic with talk -overswitch, 6 Channels with individual fadersplus cross fade, Cue Headphone Monitor. 8Sound Effects. Useful combination of thefollowing inputs:- 3 turntables (mag), 3miss, 5 Line for CD, Tape, Video etc.

Price £144.99 + £5.00 P&P SIZE: 482 x 240 x 120mm

OMP/MF 200 Mos-Fet Output power 200 wattsR.M.S. into 4 ohms, frequency response 1Hz - 100KHz-3dB, Damping Factor --. 300, Slew Rate 50V/uS,T.H.D. typical 0.001%, Input Sensitivity 500mV, S.N.R.-110 dB. Size 300 x 155 x 100mm.PRICE £64.35 - £4.00 P&P

OMP/MF 300 Mos-Fet Output power 300 wattsR.M.S. into 4 ohms, frequency response 1Hz - 100KHz-3dB, Damping Factor -. 300, Slew Rate 60V/uS,T.H.D. typical 0.001%, Input Sensitivity 500mV, S.N.R.-110 dB. Size 330 x 175 x 100mm.PRICE £81.75 - £5.00 P&P

OMP/MF 450 Mos-Fet Output power 450 wattsR.M.S. into 4 ohms, frequency response 1Hz - 100KHz-3dB, Damping Factor > 300, Slew Rate 75V/uS,T.H.D. typical 0.001%, Input Sensitivity 500mV, S.N.R.-110 dB, Fan Cooled, D.C. Loudspeaker Protection, 2Second Anti -Thump Delay. Size 385 x 210 x 105mm.PRICE £132.85 - £5.00 P&P

OMP/MF 1000 Mos-Fet Output power 1000 wattsR.M.S. into 2 ohms, 725 watts R.M.S. into 4 ohms,frequency response 1Hz - 100KHz -3dB, DampingFactor 300, Slew Rate 75V/uS, T.H.D. typical0.002%, Input Sensitivity 500mV, S.N.R. -110 dB, FanCooled, D.C. Loudspeaker Protection, 2 SecondAnti -Thump Delay. Size 422 x 300 x 125mm.PRICE £259.00 £12.00 P&P

NOTE: MOS-FET MODULES ARE AVAILABLE IN TWO VERSIONS:STANDARD - INPUT SENS 500mV, BAND WIDTH 100KHz.PEC (PROFESSIONAL EQUIPMENT COMPATIBLE) - INPUT SENS775mV, BAND WIDTH 50KHz. ORDER STANDARD OR PEC.

Join the Piezo revolution! The law dynamic mass (no voice coil) of a Piezo tweeter produces an improvedtransient response with a lower distortion level than ordinary dynamic tweeters. As a crossover is not requiredthese units can be added to existing speaker systems of up to 100 watts (more if two are put in series. FREEEXPLANATORY LEAFLETS ARE SUPPLIED WITH EACH TWEETER.

TYPE 'A' (KSN1036A) 3" round with protective wire mesh. Ideal forbookshelf and medium sized Hi-Fi apeakers. Price C4.90 - 50p PAP.TYPE 'B' (KSN1005A) 3Y," super horn for general purpose speakers,

T PE disco and P.A. systems etc. Price £5.99 - 50p P&P.TYPE 'C' (KSN1016A) 2"x5" wide dispersion horn for quality Hi-Fi sys-tems and quality discos etc. Price £6.99 - 50p P&P.TYPE 'D' (KSN1025A) 2"x6" wide dispersion horn. Upper frequencyresponse retained extending down to mid -range (2KHz). Suitable for highquality Hi-Fi systems and quality discos. Price £9.99 - 50p P&P.TYPE 'E' (KSN1038A) Th" horn tweeter with attractive silver finish trim.Suitable for Hi-Fi monitor systems etc. Price £5.99 - 50p P&P.LEVEL CONTROL Combines, on a recessed mounting plate, level controland cabinet input jack socket. 85x85mm. Price 04.10 50p P&P.

TYPE (7

TYPE D

411111Mlompopp*

A new range of quality loudspeakers designed to take advantage of the latestspeaker technology and enclosure designs. Both models utilize studio quality12' cast aluminium loudspeakers with factory fitted grilles, wide dispersionconstant directivity horns. extruded aluminium corner protection and steelball corners, complimented with heavy duty black covering. The enclosuresare fitted as standard with top hats for optional loudspeaker stands

POWER RATINGS QUOTED IN WATTS RMS FOR EACH CABINETFREQUENCY RESPONSE FULL RANGE 45Hz - 20KHz

ibl FC 12-100WATTS (100dB) PRICE C159.00 PER PAIRibl FC 12-200WATTS (100dB) PRICE £175.00 PER PAIR

SPECIALIST CARRIER DEL. C12.50 PER PAIR

OPTIONAL STANDS PRICE PER PAIR C49.00Delivery £6.00 per pair

LOUDSPEAKER LARGE SELECTION OF SPECIALIST LOUDSPEAKERSAVAILABLE, INCLUDING CABINET FITTINGS, SPEAKERGRILLES, CROSS-OVERS AND HIGH POWER, HIGHFREQUENCY BULLETS AND HORNS, LARGE (A4) S.A.E.(60p STAMPED) FOR COMPLETE LIST.

McKenzie and Fane Loudspeakers are also available.

EMINENCE:- INSTRUMENTS, P.A., DISCO, ETC

ALL EMINENCE UNITS 8 OHMS IMPEDANCE8" 100 WATT R.M.S. ME8-100 GEN. PURPOSE, LEAD GUITAR, EXCELLENT MID, DISCO.RES. FRED. 72Hz, FREQ. RESP. TO 4KHz, SENS 97dB. PRICE C32.71 C2.00 P&P10" 100 WATT R.M.S. ME10-100 GUITAR, VOCAL, KEYBOARD, DISCO, EXCELLENT MID.RES. FREQ. 71Hz, FRED. RESP. TO 7KHz, SENS97dB. PRICE 033.74 - C2.50 P&P10" 200 WATT R.M.S. ME10-200 GUITAR, KEYB'D, DISCO, VOCAL, EXCELLENT HIGH POWER MID.RES. FRED. 65Hz, FRED. RESP. TO 3.5KHz, SENS 99dB. PRICE C43.47 C2.50 P&P12" 100 WATT R.M.S. ME12-100LE GEN. PURPOSE, LEAD GUITAR, DISCO, STAGE MONITOR.RES.FREQ. 49Hz, FRED. RESP. TO 6KHz, SENS 100dB. PRICE C35.64 - £3.50 P&P12" 100 WATT R.M.S. ME12-100LT (TWIN CONE) WIDE RESPONSE, P.A., VOCAL, STAGEMONITOR. RES. FRED 42Hz, FRED. RESP. TO 10KHz, SENS 98dB. PRICE 036.67 - C3.50 P&P12" 200 WATT R.M.S. ME12-200 GEN. PURPOSE, GUITAR, DISCO, VOCAL, EXCELLENT MID.RES. FRED. 58Hz, FREQ. RESP. TO 6KHz, SENS 98dB. PRICE £46.71 r 03.50 P&P12" 300 WATT R.M.S ME12-300GP HIGH POWER BASS, LEAD GUITAR, KEYBOARD, DISCO ETC.RES. FRED. 47Hz, FRED. RESP. TO 5KHz, SENS 103dB. PRICE C70.19 C3.50 P&P15" 200 WATT R.M.S. ME15-200 GEN. PURPOSE BASS, INCLUDING BASS GUITAR.RES. FRED. 461-1., FREQ. RESP. TO 5KHz, SENS 99dB. PRICE C50.72 C4.00 P&P15" 300 WATT R.M.S. ME15-300 HIGH POWER BASS, INCLUDING BASS GUITAR.RES. FREQ. 39Hz, FRED. RESP. TO 3KHz, SENS 103dB. PRICE 073.34 - C4.00 P&P

EARBENDERS:- HPFI, STUDIO, IN -CAR, ETCALL EARBENDER UNITS 8 OHMS (Except EB8-50 EB10-50 which are dual impedance tapped n 4 8, a ohm)BASS, SINGLE CONE, HIGH COMPLIANCE, ROLLED SURROUNDB" 50watt EB8-50 DUAL IMPEDENCE, TAPPED 4/8 OHM BASS, HI-FI, IN -CAR.RES. FREQ. 40Hz, FREO. RESP. TO 7KHz SENS 97dB. PRICE C8.90 - C2.00 P&P10" 50WATT EB10-50 DUAL IMPEDENCE, TAPPED 4/8 OHM BASS, HI-FI, IN -CAR.RES. FRED. 40Hz, FRED. RESP. TO 5KHz, SENS. 99dB. PRICE £13.65 - C2.50 P&P10" 100WATT EB10-100 BASS, HI-FI, STUDIO.RES. FRED. 35Hz, FRED. RESP. TO 3KHz, SENS 96dB. PRICE C30.39 - C3.50 P&P12" 100WATT EB12-100 BASS, STUDIO, HI-FI, EXCELLENT DISCO.RES. FRED. 26Hz, FREQ. RESP. TO 3KHz, SENS 93dB. PRICE 042.12 03.50 P&PFULL RANGE TWIN CONE, HIGH COMPLIANCE, ROLLED SURROUND5'4" 6OWATT EB5-60TC (TWIN CONE) HI-FI, MULTI -ARRAY DISCO ETC.RES. FRED. 63Hz, FREQ. RESP. TO 20KHz, SENS 92dB. PRICE 09.99 C1.50 P&P61,2" 60WATT EB6-60TC (TWIN CONE) HI-FI, MULTI -ARRAY DISCO ETC.RES. FRED. 38Hz, FRED. RESP. TO 20KHz, SENS 94dB. PRICE 010.99 - 1.50 P&P8" 6OWATT EB8-60TC (TWIN CONE) HI-FI, MILTI-ARRAY DISCO ETC.RES. FRED. 40Hz, FRED. RESP. TO 18KHz, SENS 89dB. PRICE 012.99 - C1.50 P&P10" 60WATT EB10-60TC (TWIN CONE) HI-FI, MULTI ARRAY DISCO ETC.RES. FRED. 35Hz, FRED. RESP. TO 12KHz, SENS 98dB. PRICE C16.49 - C2.00 P&P

PRICES: 150W 049.99 250W 099.99400W 0109.95 P&P £2.00 EACH

THREE SUPERB HIGH POWERCAR STEREO BOOSTER AMPLIFIERS150 WATTS (75 75) Stereo, 150WBridged Mono250 WATTS (125 125) Stereo, 250WBridged Mono400 WATTS (200 - 200) Stereo, 400WBridged MonoALL POWERS INTO 4 OHMSFeatures:* Stereo, bridgable mono * Choice ofhigh & low level inputs * L & R levelcontrols * Remote on -off * Speaker &thermal orotectio

POSTAL CHARGES PER ORDER £1.00 MINIMUM. OFFICIALORDERS FROM SCHOOLS, COLLEGES, GOVT. BODIES, PLCe ETC.PRICES INCLUSIVE OF V.A.T. SALES COUNTER. VISA AND

ACCESS ACCEPTED BY POST, PHONE OR FAX

PROVEN TRANSMITTER DESIGNS INCLUDING GLASS FIBREPRINTED CIRCUIT BOARD AND HIGH DUALITY COMPONENTS

COMPLETE WITH CIRCUIT AND INSTRUCTIONS3W TRANSMITTER 80-108MHz, VARICAP CONTROLLED PROFESSIONAL

PERFORMANCE, RANGE UP TO 3 MILES, SIZE 38 x 123mm. SUPPLY 12V a 0.5AMP.

PRICE C14.85 - C1.00 P&PFM MICRO TRANSMITTER 100.108MHz, VARICAP TUNED, COMPLETE WITHVERY SENS FET MIC, RANGE 100-300m. SIZE 56 r 46mm, SUPPLY 90 BATTERY.

PHOTO: 3W FM TRANSMITTER

VISA

B.K. ELECTRONICSUNITS 1 & 5 COMET WAY, SOUTHEND-ON-SEA,

ESSEX. SS2 5TR.Tel.: 0702 - 527572 Fax.: 0702 - 420243


10

INTEGRATED A.F. AMPLIFIER - PART 2

ConstructionThe preamplifier section is intendedto be built on the printed -circuitboard shown in Fig. 4. Since the vari-ous connectors and controls (exceptSi and S2) are mounted directly on tothe board, the completion of theboard should not present any difficul-ties. Take care, however, not to over-look any of the wire bridges, whichshould be soldered in place first.Circuits IC5 and IC6 are intended tobe fitted on a common heat sink, withinsulating washers between the chipsand the heat sink. The completedboard is shown in Fig. 6.

The output amplifier is best builton the printed -circuit board shown inFig. 7. Two of these boards are, ofcourse, needed for a stereo version.As usual, start populating the boardby soldering the wire bridges andsmall components in place. Pay par-ticular attention to the polarity of Cliand C13. It is advisable to solder R19and R20 slightly off the board: thishelps the cooling of these compo-

936062-2

WEE I*-o

01 848100 0 0( R49 to

C30

0 1

0 R47

=MI

C29

10 C20 OHO

1001E) 0 R40 0

10 C12 OH°A L

oi R33 to

rRat iL

01 R4

01R41

01 R42 10

C24 C23

Design by T. Giesberts

Main parameters

Sensitivity (all inputs)Signal-to-noise ratio (input short-circuited)

(input open -circuited)Input impedance (all inputs)Slew rateLine output impedanceLine outputTape output impedanceTape outputBandwidth (80 W into 4 Q)Harmonic distortion (45 W into 8 Q at 1 kHz)

(85 W into 4 Q at 1 kHz)

Maximum output power

300 mV100 dB (1 W into 8 L2)

80 dB (1 W into 8 f)471d2100 V ps-1

100 C2

1 V into 100 n1k)2300 mV into 1 kS/10 Hz - 70 kHz0.1%0.2%85 W into 4 cl45 W into 8 Q

nents. Use heavy-duty solder pins forall external connections to reduce theresistance to a minimum (rememberthat very high currents flow).

01- R2 10 01 R1

C26

C11 C6

2. 00110 of 824.100 'r 01 R23 }0

01 R28 to 2, t cm R27 10

1'01 1130 l001 a41 T°RII° c47. cill434) °A).111°

P4

01401 R 610 -Ho cs tvejo

oi 68 #0

4111.111.1.111,110,

Mount T5, T6 and T7 on a commonheat sink with a thermal rating of0.6° W. Insulate the transistorsfrom one another and from the heat

01 R6 10

+ 00 0 0

01 R38 10

IVC17 C18

111111.11.1111.411.4

Of R10 10

.4 AQ' Q-.

Q Cl

a 15' z5. rs211 10

1 9

c41

P

Fig. 4a. Printed -circuit board for the preamplifier section: component layout.


INTEGRATED AMPLIFIER - 2 w

THD+N(%)

0.1

0.01

45W/BR

2W/40

1W/8S1

0.00120 100 1k

f (Hz)

10k 20k

936062X - 15

Fig. 5. Distortion plus noise vs frequency characteristic.

sink with ceramic washers (do notuse mica or silicon types) and heattransfer paste.

AssemblyFit he amplifiers and power supply ina standard 19 in. instrument case asshown in Fig. 11; the wiring diagramis shown in Fig. 8.

Fit the four 10 000 FF capacitorsand the eight 0.1 Q, 5 W, resistors

(power supply), and the series resistorfor the on -off LED, on a separatepiece of prototyping board.

Fix all the boards on insulatedspacers to the bottom of the case.

Use insulated wire of at least1.5 mm2 diameter for the connectionsin the power suply and also for thepower lines.

Link box header K11 to Si and S2with flatcable (see Fig. 1, Part 1).

CalibrationSet P1 and P2 on the output amplifierboard to the centre of their travel.Short-circuit the input of the outputamplifier and switch on the supplyvoltage. Connect a good -quality milli -voltmeter across R19 and R20 in turnand adjust P2 for a meter reading of22 mV. The quiescent current is thenaround 100 mA. Next, adjust P1 foran amplifier output of 0 V (or verynearly so). If that can not be achie-ved, replace T2 by another transistorwhich makes it possible.

Parts list

PREAMPLIFIER: Fig. 1 and Fig. 4Resistors:R1 -R8 = 47 IcS2Rg, R10 = 11c52R11 -R18, R29, R36 = 10 MIR19, R20 = 2.2 ki2R21, R22, R32, R39 = 1 MS2R23, R25 = 4.22 kS2, 1%R24, R26 = 1.0 1d2, 1%R27, R28, R34, R35 = 2.7 kQR30, R31, R37, R38 = 1.8 kQR33, R40 = 100 1-2R41, R43 = 1.24 k52, 1%R42, R44 = 10.7 162, 1%

,R462mc2=220 Q, 5 W

R4 = 18R48:

= 4:70kS2P1, P3, P4 = 10 kQ, linear, stereo

936062-2

Fig. 4b. Printed -circuit for the preamplifier section: track layout.


CEI AUDIO & HI-FI

P2 = 10 kQ, logarithmic, stereo

Capacitors:C1 -C4 = 10 pF, 63 V, radialC5, C6, C13, Ci4, C21, C22, C25,

C26 = 100 nFC7, C15 = 180 nFC8, Cg, C16, C17 =C10, C18 = 3.9 nFC11, C19 = 47 pFC12, C20 = 2.2 pF, 50 V, polytheneC23, C24 = 22 pF, 25 V, radialC27, C28 = 220 pF, 40 V, radialC29 = 2.2 pF, 63 V, radialC30 = 100 pF, 40 V, radial

Semiconductors:D1, D2 = 1N4148D3, D4 = 1N4003T1 = BC517

68 nF

Integrated circuits:IC1, IC2 = LM1037IC3, IC4 = NE5532IC5 = LM317IC6 = LM337

Miscellaneous:K1 -K10 = audio socket for PCB

mountingK11 = 10 -way male box header and

female counterpartS1, S2 = 1 -pole, 12 -position rotary

switchRe1 = 2 -contact change -over relay for

PCB mountingHeat sink (IC5; IC6) 4° W-1Insulating mounting kit for IC5, IC630 cm (12 in) 10 -core flatcable4 off extension spindle for P1 -P4PCB Ref. 936062-2

OUTPUT AMPLIFIER: Fig. 2 and 7Resistors:RI, R17 = 1k4R2 = 100 k52R3 = 2.7 kitR4= 150 QR5, R6 = 470 kQR7 -R10 = 2.2 MQR11 = 4.71.(52R12 = 5.6 IcQR13, R14 = 560 QR15, R16 = 47 QR18 = 220 QR19, R20 = 0.22 Q, 5 WP1 = 2.5 Id2 presetP2 = 250 Q preset

Capacitors:C1 = 1 nFC2, C3, C9 = 1 pFC4 = 100 pF, 10 V, bipolarC5, C6 = 150 nFC7, C8 = 100 pFC10, C12 = 680 nFC11, C13 = 10 000 pF, 40 V, radial

Semiconductors:Ti = BC550CT2 = BC560C

T3 = BC640T4 = BC639T5 = BD139T6 = BDV65BT7 = BDV64B

C

+30V0

Miscellaneous:Heat sink (T5 -T7), 0.6 °C W-1

(160x75 mm)Mounting insulating kits for T5 -T7PCB Ref. 936062-1

01-1.11-J-.

r

Fig. 6. Completed printed -circuit board for the preamplifier. Thepotentiometers are fitted with extension spindles.

P4

T6 ¶6

C9 0111-0

Or R17 10 0

7 eop -

0110 op or R3 loC2 C3 C4 T2

771 T4

-30V0

-IF gcgoag,it

irvwcw vv.

Fig. 7. Printed -circuit board for the output amplifier section.

013


INTEGRATED AF AMPLIFIER - 2

POWER SUPPLY: Fig. 3Resistors:RI -R8 = 0.1 f2, 5 WR9 = 10 kg -2Capacitors:C1 -C4 = 10 000 pF, 50 V

Semiconductors:D1 = LED, low currentB1 = bridge rectifier B200C35Tri = toroidal mains transformer,

secondary 2x22 V, 300 VA (mono),600 VA (stereo)

GENERALStandard 19 in, 2 -unit high

instrument caseMains entry with integral fusaeMains on/off switch with integral

LED indicator[936062]

oar

I

u uuu.\"><"7\`"\""\""\""`\""`N"`\a:-

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Fig. 8. Wiring diagram of the complete integrated amplifier.


14 AUDIO & HI-FI

+15dB

+10dB

+5dB

0dB

-5dB

-10dB

-15dB20Hz100Hz 1 kHz 10kHz 20kHz

Ie

936062-5-15

Fig. 10. Frequency characteristics of the amplifier with thetone control at its extreme settings

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Air

Fig. 11. Inside top view of the completed prototype amplifier.

411016.,

0 0 0 0 0 0

Fig. 9. Suggested front panel. Fig. 12. Rear view of the integrated amplifier.


Please mention ELEKTOR ELECTRONICS when contacting advertisers

ESR ELECTRONIC COMPONENTSStation. Road, Cullercoats, DEPT. EETyne & Wear NE30 4PQTel. 091 251 4363 Fax. 091 252.2296

741.S -Series

74150074150174150274130374 LSO474L50574L308741S09741510741S1077413109741311741511274151137410114741512741012274101237410125741512674LS13741513274LS13374LS136741513874151397415147415145741514774151487415157415151741515374LS154741515574151567415157741S15874151607414161741516274LS16374151647415165741517074L017374151747415175741.3190741919174L51927415153741519574101967415197741_5207415217415227415221741S2407415241741524274102437415244741,5245741524774152517415257741_5258741526741_526674152774L 5273741_527974153074153274 LS3657410367741536874LS3774153737415374741537574153777415378741538741539074LS393741039574 LS399741340741_54274LS477410517410670741_573741574741075741_07674158374158574L586741S90741492741593

£0.22£0.14£0.14£014£0.14£0.14£0.14

0.140.14

£0.23£0.21£0.17£0.21£0.21£0.21£0.14£0.31£0.31£0.21£0.2110,14£0.21£0.18£0.16£0.24£0.25£0.18£0.56£1.2610.70£0.14C0.25£0.25£0.7010.25£0,36£0.25£0.25£0.3210.32£0.32£0.32£0.26£0.4810.30£0.24£0.24£0.24£0.2510.24£0.42£0.24£0.24£0.24£0.24

0.16£0.14£0.14£0.36£0.32£0.32£0.32£0.32f0.32£0.36£0.32£0.24£0.24£0.24£0.14£0.14£0.14£0.32£0.25£0.14£0.14£0.21£0.21£0.21£0.14E0.32£0.32£0.34£0.32£0.6210.14£0.2510.24£0.26£0.62£0.14£0.25E0 72£0.14£0.69£0.17£0.25£0.19£0.25£0.31£0.35£0.20£0.23£0.35£0.25

ENAMELLEDCOPPER

WIRE

AS 2oz Reels14 SWG16 SWG18 SWG20 SWG22 SWG24 SWG26 SWG28 SWG30 SWG32 SWG34 SWG36 SWG38 SWG40 SWG

10,63£0.67£0.67£0.72£0.76£0.80£0,89£0.91£0.93£0.93£0.9911.04£1.10£1.22

4000. Series

40004001400240064007400840094010401140124013401440154016401740184019402040214022402340244025402640274028402940304031403340344035404040414042404340444046404740484049405040514052405340544055406040634066406740684069407040714072407340754076407740814082408540864089409340944095409740984099450245034508451045114512451445154516451845204521452645274528452945324534453645364541454345554566456045664572458445854724401064010940163401744017540193

£0.17£0.21£0.170,40

£0.28£0.31£0.19£0.23£0.26£0.16£0.21£0.3010.31£0.113£0.27£0.27£0.19£0.31£0.31£0.32£0.16£0.2110.15£0.59£0.18£0.22£0.36£0.17£0.70£0.56£1.24£0.31£0.29£0.31£0.22£0.28£0.35£0.31[0.480.31

£0.20£0.20£0.36£0.25£0.25£0.56/0.34.£0 E

10.29£0.18£1.91£0.16£0.20£0.17£0.20£0.17£0.17£0.17£0.300.1710.14£0.21£0.28£0.26£0.55[0.30£0.31£0.56£1.20

£0.38£0.38£0.31£0.90£0.26[0.3240.32£0.77£0.98£0.31£0.27£0.26£0.62£0.4000.40£0.4010.44£0.32£2.48£1.00£0.37£0.33£0.46£0.34£0.34£1.18£1.96£0.25£0.24£0.32£0.70£0.31£0.50£0.46£0.34£0.36£0.60

21416132N17112141893252218425221942N2222A2N2646252904425290542529072N2926253053253054253055214344025370225370321437042N37052N37062N37712N377221437732538192538202539042N39052539062540362552962N53212148107AC126AC127AC128AC187AC188ACY17AD149AD161AD1625C107BC10783C1041BC108ABC108CBC109BC109CBC114901150C1160C11800132BC134BC135

0140BC141BC142BC1438014900154BC157BC159BC160BC170BC170BBC171BC171650172Oct 72500177BC17800179BC162BC182L6018218BC1836010316018315BC184601841

£0.31£0.26£0.29£0.28£0.25£0.16£0.80£0.25£0.23£0.20£0.16£0.27£0.90£0.62£0.50£0.09£0.10£0.10£0.10£0.10£1.44£1.51£1.79£0.40£0.58£0.10£0.10£0.10£0.31£0.57£0.57£0.60£0.30E0.30£0.28[0.45£0.37£3.84E1.67£0.92£0.92£0.14£0.15[0.14£0.14£016£0.14£0 1'f0.41£0.41£0.41£0.41£0.36£0.36£0.36£0.2510.27£0.31£0.34£0.21£0.36£0,12£0.12£0.28£0.16£0.16£0.11£0.16£0.13£0.13£0.18L0.18£0.17£0.08£0.08£0.08£0.08£0.08£0.08£0.08£0.08

TRIACSZ0105DA £0.42TIC206D £0.65TIC2260 £0.73BTA08-6008 10.84TIC2360 £0.96DIAC £0.20

VOLTAGEREGULATORS781057811278L1579L0579L1279L15780578127815790579127915LM3I7TL M723L200CVLM323KLM338K

£0.24[0.24£0.24£0.28£0.28£0.28£0.28£0.2810.28£0.38£0.38£0,38£0.65£0.29£1.16£2.70£5.52

OPTO DEVICES5mm Red LED5mm Green LED5mm Yellow LED5mm Orange LED3mm Red LED3mm Green LED3mm 'Yellow LED3mm Orange LED5mm Flashing RedSnore Flashing Green5mm Eft Colour5mm Tri Colour5mm Plastic Bezel3mm Plastic Bezel0 r 7 Segment Display Redcommon anodecommon cathode

£0.09£0,10£0.10£0.10£0.08£0.1210.1340.13£0.50£0.54£0.36£0.48£0.04f0.05

£1.14£1.14

BC186BC204C502061300207C90208802095BC212BC212LBC212LBBC213BC213LCBC214BC2141802378BC238CBC2390BC251BC252002610B02620602676BC307BC308BC327BC328BC3378C338BC414CBC441BC461BC463BC478BC479BC490BC516BC5178052780528BC5378 C546CBC547CBC548CBC549CB 0550CBC5564BC557CBC558CBC559C8C560680637BC638506398C640BCY708CY71BCY72K213580136130137BD138801390014080150C001558016650187B0201BD2028020350204BD22280225B(32328 02375D238802408002430B02444BD246B044180442

0.33

£0.72£0.72£0.72£0.72£0.72£0.0810,08£0.08£0.08£0,08£0,08E0.08£0.09£0.09£0.10£0.13£0.1310.24£0.24£0.30£0.10£0.10£0.10£0.10£0.10£0.100,13£0.40£0.40

0.29£0.32£0.32£0.24£0.22£0.2010.20£0.20£0.20f 0.08£0.09

0.08£0.10£0.08£0.08£0.013£0.08£0.08£0.0910,21£0.21£0.21£0.21£0.21£0.20£0.20£0.20I0.21£0.22£0.22£0.23£0.24£0.82£0.42

0.35£0.3910.40£0.40£0.4010.40£0.40£0.42£0,38£0,32£0.32£0.37£0.50£0.53£1.06£0.41£0.41

BD534BD535BD5368064680646BD650BD70700807BDX32BOX330BDX34CBOX530BD X54C8E180BF19258185BF194881958E2448E2578E2598833788355684236E451BF4598E469BFX29BFX84BFX858 FY50BEY518 FY52135107135170BSW66BU126BU205BU2084BU326A8050080508561.152680806BUX84IRF540168740MJ11015MJ11016MJ2501MJ3001MJ E340MJE350MPS413MPSA42MRF475TIP121TIPI22TIP125TIP127TIP132TIP137TIP142TIP147TIP2955TIP29CTIP3055TIP30CTIP31 CTIP32CTIP33CTIP414TIP42CTIP47TIP48TI P50VN1OKMVN66AFZTX300ZTX500

THYRISTORSPO10244T101060TIC116DTIC126D

£0.30£0.40£0.66£0.77

£0.47£0.48£0.65£0.5210.52£0.53£0.42£0.80£1.78£0.46£0.50£0.47£0.50

0.31£0.3110.31£0.150.19£0.35£0.33£0.33£0.36£0.38£0.13£0.19£0.33£0.36£0.29£0.31£0.31£0.29£0.26£0.28£0.2110.21£1.35£1.70f1.82£1.73£1.90£2.32£1.76£2.24£1.36£0.78£1.6041.80U11£2.11£1.60£1.52£0.40£0.42£0.12£0.17£6,21£0.35[0.40£0.37£0.37CO 46£0.46£1.08£1.12£0.63£0.31£0.63£0.31£0.34£0.32£0.72[0.48£0.38£0.48£0.62£0.53£0.44£1 .50£0.16£0.16

HARDWARE12 Box 75 x 56 x 25mm £0.82T3 Box 75 x 51 x 25mm 10.82Td Box 111 x 57 x 22mm £0.98MB1 Box 79 x61 x 40mm 11 .44MB2 Box 100 x 76 x 41mrn £1.56MB3 Box 118 x 98 x 45arn £1.82MB5 Box 150x 100 x 60rom £2.50

LINEAR ICs

CA3118CA324CA555CA741 CECA747CECA3046043080CA3130CA3130ECA31400432401CL7621ICM7555ICM7556

M301AM348NF351 NF353F356M358NM377M3805M381M386M387M3921,1M3935M748CNM1458M 3900M3914M3915

MC3340MC4558NE531NE556NNE567NNE5532NE5534TBA120STBA810STBA820MTDA2030TL061TL062TL0641.071CPTL072CPTL074CNTL081TL082CPTL08404UA733ULN 2003ULN2004ZN414ZZN425EZN4266ZN427EZN428EZN435E25448E

£0.28£0.35£0:22'00 26£0.39£0.37£0.72£0.98£0.98£0.56L1.12£1.70£0.43

0.96£0.25£0.31£0.36£0.41L0.84£0.27£2.57E1.12£2.70£0.48£1.60£0.79£0.28£0.31£0.2610.72£2.70£2.70£1 .60£0.36Et .56£0.36£0.36£0.80£0.66£0.77£0.6810.39el .35£0.35£0.42

0.46£0.32£0.34£0.48£0.33£0.34£0.46£0.64£0.52£0.48£1.04£4.68£2.61£8.82£6.12£5.31E7.92

EPROMS &RAMS

271627322764-2527C64-2521728-2027C128-2027256.2027C256-20

27C51227C0106116.106264-1082258-104164.1541256.10511000-8514256.8

44.4644.84£3.00£2.80£3.69£3.31£3.99£3.57

[3.69£4.97iI.53L3.06£4.83£1.78£2.130

C5.61

45.61

DIL SOCKETS8 Pm14 Pin16 Pin16 Pin20 Pm24 Pin28 Pin40 Pin

0,07£0.11£0.15£0.15£0.16£0.19£0.22£0.25

ELECTROLYTIC RADIAL CAPACITORS

uF0.471.02247102247100220470100022004700

16V

£0.05£0.05£0.06£0.06£0.09£0.15£0.22£0.37

25V

£0.05£0.05£0.06£0.09£0,12£0.19£0.29£0.5711.11

63V 100V 450V£0.05£0.0510.05£0.05£0.06£0.0910,11£0.11£0.31£0.57

£0.07£0.06£0.06£0.08£0.08

£0.15£0.18f0.30£048

ELECTROLYTIC AXIAL CAPACITORS

5

Antex Soldering irons

:aBNC Solder Plug 508 £0.93

M 12 WattC 15 Watt

(8.50£8.19

BNC Solder Plug 75RBNC Crimp Plug 505

£0.96£0.68

G i8 Watt L8.75 BNC Crow Plug 75R £0.68CS 17 Watt £8.65 BNC Solder Ski £1.08XS 25 Watt £8.75 BNC Chassis Skt £0.80GASCAT 15.87 PL259 5 2mm £0.68574 STAND £2,85 PL25911 mm £0.6235Watt Gas Iron £11,58 RND UHF socket £0.68Desolder Pump £3.00 SOR UHF socket £0.45Antistatic Pump £4,30 F Plug RG58 £0.3022SWG 0 5Kg Solder £7.40 F Plug RG6 £0.27185WG 0 5Kg Solderlatrn 3 yds SolderDesolder Braid

£6.60£0.62£0.87

N Plug RG8N Socket RG80140 Crimp Pliers

£1.60£1.40

£15.50

PCB EQUIPMENTUS EXPOSURE UNITPLASTIC DEVELOPING TRAYPHOTO RESIST AEROSOL SPRAY (100ml)FERRIC CHLORIDE CRYSTALS (0.5Kg)TIN PLATING POWDER (909)ETCH RESIST PENPCB POLISHING BLOCK

STRIPBOARD 0.1 PITCH64mm x 25mm £0.2764mm x 95mm 113.9064mm x 431mm £3.2295mm x 127mm £1.5095mm x 95mm £1.1095mm x 431 mm £4.80100mm x 160mm £1 60119mm x 454erm £6.20

PHOTO RESIST BOARD(G. Fibre)

£67.38£1.35£3.90£2.45

£10.8010,72£1.84

BREADBOARD81mm z 60mrn £3.06175mm x 42mm £3.74175mm x 67num £5.56203rorn x 75mm includesmounting plate & posts £7.36

COPPER BOARD (G. Fibre)100mm x 160mm C0.90110mm z 220mm £1.24

PHOTO RESIST BOARD(Paper)

£0.86 E0,67£1.62 £1.24£2.09 £1.58£2.41 Et x 10 £4.63

CAPACITORSCeramic Mtn! Disc 100 & 63V

1 OpF 10 100nF1pF-1nF £0.06, 1n2 -2n7 10.07,3n3.4n7 0.12,10n & 12n £0.07

Polystyrene 160V 5% 47pF to 10r1F47p -2n210.09, 2n7 1 On £0.12

D CONNECTORSPlug

9 Pm £0.2915 Pin £0.3915 Pin H D. £0.8123 Pin £0.4025 Pin £0.48

9 Way plastic cover15 Way plastic cover23 Way plastic cover25 Way plastic cover

Socket£0.30£0.39£0.90£0.49£0.50

£0.30£0.33£0.36£0.36

BRIDGERECTIFIERS

W0051 5A 50V £0.19WO2 1 5A 200V £0.20BR32 3A 200V £0,360662 6A 200V 10.701004 10A 400V £1.39

SWITCHES3aerp 250v 6 4rnin ,,k mountingSPST Toggle £0.56SPOT Toggle 10.60SPOT CO Tog £0.64DPDT Toggle £0.68DPDT CO Toggle £0.76DPDT CO Toggle(biased) £1.20DPDT CO Toggle(biased 1 way) £1.20DPDT min, slide £0.15Rotary Wafer 18-12W. 2P -6W,38.4W 4P -3W £0.78Key Switch SPST £2.70Push to make £0.25Push to break £0.28Latching Push Sqr £0.63PCB Tact 6 x 6rnm -£0.25

RESISTORS025W 5% CF El 2 Series 10.60/1000 5W 5% CE E12 Series £0.95/1000 25W 1% MF E24 Series £1.72/100POTS Log or Lm 470R IMO 25mm die 0.251n

shaft £0.42PRESETS Enclosed Horz

Of Vert 1005 IMO 0.15W £0.15PRESETS Skeleton Hors

or Vert 100R IMO 0 1W £0.11* PLEASE STATE VALUE REQUIRED *

COMPUTER ACCESSORIES

Parallel Printer Lead 2m'RS232 Lead (all pins) Male Male

£6.90£3,75[3.80

DIODESZener Diodes 2V7 33V8ZY8B400Mw £0.0602085 1 3W £0.14RS232 Lead (all pins) Female- Male

Centronics 36 Way Lead Male Male £4.78 1 N4001 £0.06Gender Changers 1 N4002 £0.079 Way D Mull Female to Female £1 81 1144003 £0.079 Way D Mini Male to Male £1.98 154004 £0.0725 Way D Mini Female to Female £2.23 154005 £0.0725 Way D Mini Male to Male9 Way D Female to Female9 Way 0 Male to Male

£2.23£2.33f2.33

1540061N4007

£0.0810.08

25 Way D Female to Female £2.71 1145400 £0.0925 Way D Male no Male f2.71 1N5401 £0.09Adaptors 145402 £0.099 Way Male to 25 Way Female 12,71 1 N5404 £0.119Way Femate to 25Way Male 12 71 1 N5406 £0.1125 Way Male to 9 Way Female £2.33 1 55407 £0.1425 Way D Male to 36 Way Centronic £3.56 1 5 5408 £0.1525 Way Null Modem Female Female £3.02 114914 £0.0625 Way Null Modem Male to Female25 Way Null Modern Male to MaleRS232 Surge Protector Male Female

£3.02£3.02£6.12

1619161144148

£0.06£0,05

RS232 Jumper Box Male to Female f3D2 BY133 £0.13RS232 Tester (7 LEDs) Male Female £6.59 0A47 £0.28Data Switch Boxes 0A90 £0.07Serial Switch box 2 Way Ail3 £9.20 0A91 £0.10Serial Switch box - 3 Way A/ 13/C £13.16 OA202 L0.29Serial Switch boa 4 Way 4[13/C/D £15.15 BA157 £0.10Serial Switch box Cross overParallel box 2 Way 4/13

£19.69£11.84 BA158 £0.10

Parallel box 3 Way A/13/C/ £17.11 BA159 £0.10Parallel box 4 Way 519/0/0 £18.43 1144149 £0.06Parallel box Cross over £20.42 04200 £0.10

ORDERING INFORMATIONuF 16V 25V 63V 100y 450V All prices exclude VAT.0 47 £0.15 Please add £1.25 carriage to all orders and VAT (17.5%).102.2

£0.10£0.10

£0.10£0.10

£0.1910.22 No minimum order charge.

4710

£009£0.12

£0.10£0.12

£0.1010.12

£0.34£0.48 Free Computer listing with all orders over £5.00.

2247 COI 0

COM£0.11

£0,13£0.16

£0.17£0.20

DI .06£1.33 Please send payment with your order.

100 £0.10 £0.13 £0.21 £2.46 PO/Cheques made payable to220470

£0.13£0.21

£0.18£0.24

£0.42£0.69 ESR Electronic Components VISA

10002200

£0.33£0.52

£0.40£0.64

£1.05 Access & Visa cards accepted MM4700 £0.90 Offical orders from schools & colleges welcome.

II


16 Please mention ELEKTOR ELECTRONICS when comae:big advertisers

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746C251 0607490253 0 607440258 0607440273 1107410283 I 437440299 2 067440373 0 947440374 0927440377 0.99744052, POA7040540 0 98704054, 0987440573 . 387440574 1 387440646 POA7440648 POA

78012 04878515 0557905 0287935A 012793574 06079397912 001505

70124 036791274 0787115UP041510.30307918 0 307924 030791124 0 357911240P 035790105 0427901354 0427914357A 065790112 0 50791112/ 06017.37n 0 501.114317 86, 1061.8431712 055111338K 4.45mew IC 1 02U479GUIC 1 02R041954 1 80

038304,200V S1L 0576.4A,00,/ 04 16084/2039 5.1 196354/100V Sat 215

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Sealed Metal4pin Pkg

Rea . MIN

1::000:58.9°. 47,5547-- 7'.1.-'..."--10.12.15-18-18 432 19 6808.

2° 24. 2° 6 30°4.70'7' £3.02 74'32 32 768.33 33.40 8 SO. 6650/40pie*: CIAS es.

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10.444025134Z.10 695us,44,443.,, 46001141,651.54 20001645619.15 120NMC37644.15 1.60

uUPDP°141464160-C4152 41.7200

UPD4160-2 3403 65

UPD446D-I 2 60

STATIC RAM

211431 3.405260.7.10 2.40626417.12 2.4o6226618.12 4 95

62256/7.10 4%CDM61164E3 5 30

0014461174E3 55514191.6116.5 43871143-8116.5 3 6014146116117.2 21301411161161.173 260918611717 3 575140622561740 7.930516264117 12 39511218264147.20 39557082678.35 5.07551.1621312811180

18 55HM662041-12 15 80KM622564117.10 495L1451640.101 2406211441.2 340P211404.4 14070051017 330UPD4325640.1101.

573UP043256C 12 560

1S 470

UVPROMS

27012132S J%275644.1S 3 95

21C25615 3 9527025625 195027256 540270S1713.12 645275,0000.12 8 922704096.12 POA50927C1010.20 9 BO141027C102454G10

,663511427C607.207 34004270646.14 470Hry27C840.20 4 2006062532P 4.53141448271205.25 45S04482764G 3.e0642716.171 250651273214 4 40m5127640 330M8142706.1 20216

490646 44270128 30 420M964270256.30 510MA02702560.25

49550.4C275640 25 366'W525164.45 1 513

15.4527,294..25 460U00271611 45 460U702725801219 560uP02732421V 1%uP02702560.15 5130U002705120.15 6%1.103275640.25 495

EEPROMS

2858426 9 8326064 15 10%28025520 113 40

280256.75 19 602802551500 28 53X2131610 51002816.97.25 5.10

21364.7.35 122024001 16224502 21024004 29624076 540230046.20 . 4059011 1 44

93006 112937446 12893056 1 52

93066 2 16

MISC. MEMORIES

6347.1J 455411214134513C 544M427528170 39810777315.1-1007 '0401131713214.1007 12 20M984,45 n%MC514027403 2806182009N POAN420121394 249N6251539 51074025161474 609854C65544.9 3 4001.10930641 1 45

P51011.1 390T871800300 I 747131.24SION171142404709 3 15

3507C5504/172 340705516171.15 120T0551717.2 4 2070556571-15 3 6074.4040. 43Di. 140

TEL 081-471 9338 TLX 929709 VICOM G FAX 081-552 0946

DIGITAL INTEGRATED CIRCUIT SPECIALIST

4000 SERIES 138 20 40,687 0 43 74,60 0 94 74LS769 0 59 7410669 1 07 7744K51 545

1.77

C648 1.777400651 I 47

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24'1°4°5' 054741404052 0 6870104053 0687040405117 10741404060 0 47Price:74004061 2.52741404066 04670510406640.5474004067 4.7274004072 0.45745104075 0.3274004078 0.0674004094 0 64

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749C4316 0-6e74004351 0.89741404511 0 557414074511741504514 12874004515 1.4274904518 0.80745104520 0.72741407452024904534 POA74004538 0.68745104503 0.8174007001 10174007032 101745107074 1.9974007292 1.102414°22" .10740040102 ' .10

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741614 0 9874163 12874164 1.2074195 1.5774,66 1.0674174 11374175 12374180 12974184 70474165 1.7674191 1 .4,

74192 1 9174193 '6574221 1 2374259 2927.1705 116

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7414670 0 787410673 POA7410674 17 607410682 2.62741S6133 P0*7411685 POA17415656 POA7411687 POA74156887415593 7047411794 POA

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ZENER DIODESMISC.

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BRIDGERECTIFIERS

0 9A42°0°09

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40148 0 4240156 0 4240,68 0.2440.78 ' ' ' '..40.68 0 3841098 026402016 0 3640208 03840219 0.40

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74279 13$74283 12674299 POA74365 D7074367 1.9674393 29474403 POA74423 POA

7414221 0.447414224 20247410240 D427415241 0.427415742 0 427414243 0.427415244 0 427410245 0427414247 0.44

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4L47: 042. r4""40418 14140411.53 0 3240428 0 3240438 0.3640448 0 3640458 09440488 04240478 0 3840488 0 824049B 0 24404908 0.2940508 0.2240518 03440528 0 3340538 0.344054E1 06640558 062405613 04840598 2.913

40606 v T40638 0.42

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40898 9.7940938 0.2440948 0 38

4°95° 0 7°40969 1 1040978 2 75

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754VP POA0005 1.980097 0620018 062WOO 2980,91 POA0,02 1200103 0.0313

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40147 12340160 0 5440161 0 5040,62 05440163 05440174 0 34OW 75 04740181 POA40192 06240193 0 7440194 1.8240195 22440240 2.624024, , 36402,3 1.36

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40374 1 1045026 4 4245027 519.5025 4.4945040 PO44504, POA46,00 713445106 79845109 P0*45138 POA45145 10 0.145146 POA45151 19 5045152 21.4545156 15 8045157 14 313

45158 II 9445159 POA454446 27345407 6 4745411 POA45414 15 6045428 POA45433 POA45440 POA45441 POA

409357 0 05409487 0 95450697 20S451057 1 02451197 1 35451281 068451487 2 20451581 1 02451987 I 48452087 1'84521E17 1074522137 1 228826,2 0,0453480 POA453891 t 05454187 105454301 1 024555137 POA455681 1.05450581 a9540706137 0.534024497 1.35403)387 234

7440 9.467401 0 307402 0.347403 0 347404 0.407405 0.407406 0.8874084 a727407 06374071 0657408 0.377409 0 677410 0 357412 0647413 0.767414 0727416 0537417 0.487420 0.377425 0597428 0197427 0597430 0157432 0 457437 0597438 0.497440 a777442 0557045 1 267446 / 537447 0 9874474 1 677451 0 077054 0 727470 0517472 0387473 0597474 0.537475 0 677476 0 727480 1 2674, I 407485 0 587086 0537490 0.7674904 1 3,749' 7567492 0877492* 12

7493 0 6870931 0 707495/ , 707497 5 2374104 0 6774107 0 60741.0 POA74116 310741.8 POA741.9 P0P.74121 0 9874123 09474,25 06774126 09874,25 1 1974132 0 86

70110074110,7940274650374110474110574110674110774,40874110974111074141174,1,74111374151474141574142074102174112274142479.42670142774112874143074143,74153274103374133774153874154074154274114474/547741448741549741551741154741555741173741173474147474117447414757415767414764741577141578741583741483474108574106674159079191791927415937919574149874141077411107A7414,097414109A741511274151124741511374151134741411474151144741012274141237411.257411: 24474LS 26741.4. 264741.5 327411.337411 387411'3774/01367410139741414574L5147741514E1

74401517415,537415154 1607411,55741.5'56 0387410757 07410758 034

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7415352 1 687411353 1.667415363 2107415364 POA7411365 0.307411365A 0.347415366 0.3674153664 0.427415367 02974113674 0347414368 03674153684 1 727415373 0.38741$374 0.447411375 0.427414377 0.60

7411378 0.913

7415379 0.99741539,1 4.96241,300 3.40

7415398 0.987411390 0.467415393 0407415394 0.687414395A 0.94791396 70*7415398 POA7415399 0.817415423 0 987414445 POA7414450 10.89741141314 7 167416466 3.172

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714822 26 7071.4903 44 00

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1 903,3374 2 18745394 210744412 2 10744436 2.6274$437 2 62740472 222745734 262

7400 SERIESSURFACE NOUN

7451002M 0 32749503M- 0.327414504M 0.327400004 o.33

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CRYSTALS MISC. '.'`,547'C305 6 99

WM CYLINDER0 032768 089

WATCH0.032768 0 82

METAL FILM0.2519 1%

724 9.".107110 ISA 39 *aceNB Mn Oly 04714/Spas pm, 091.

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' METAL FILMPRECISION

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HIGH PRECISIONNON-1NDUCTIVE

WIRE WOUND0.33 WATT 01%

Temp Coell 307.11171.574.10R.20R 50Rpop; 2560 4,08

,00o 1209 2608.50010.111. 20 60.106.206

940103 0 2274140702 0227010803 0 26

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Please mention ELEKTOR ELECTRONICS when contacting advertisers mMICROPROCESSOR

7. SUPPORT ICs

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"2"285

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704108507041151

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18

TESTER FOR INFRA -RED REMOTE CONTROL

Design by A. Rietjens

Modern audio and video systems, virtually without exception,use infra -red remote control. If one day (normally a Sunday) the

remote control unit does not elicit a response from theassociated equipment, the tester described will quickly

establish the cause of failure (hopefully, it is just a flat battery)

Modern domestic remote control unitsfor radio, television and audio sys-

tems invariably use infra -red light topass instructions to the receiver in theassociated equipment. The transmitter,housed in a small, handheld box, usesan infra -red transmit diode, while the as-sociated receiver, built in the audio or videoequipment, uses an infra -red photo diode.When one of its control buttons is pressed,the transmitter emits a burst of high -fre-quency signals. Since humans can notsee infra -red light, it is impossible for usto observe whether the transmitter doesindeed emit signals. The present testercan detect these signals and at the sametime give a general indication of their in-tensity and quality.

How does it work?Before the tester is detailed, a brief de-scription of how an infra -red remotecontrol works may be useful. The de-scription is based on the frequentlyused Philips/Sony RC5 coding. Othermanufacturers may use different cod-ing techniques, but that does not inval-idate the method of operation nor thetester.

Each burst of IR light emitted by thetransmitter is 25 ms long and containsa 14 -bit code word-see Fig. 1. Eachburst of light is followed by an intervalof about 90 ms. Each bit in the codeword is superimposed on to a carrier of36 kHz. The carrier is not symmetric:its logic '0' period is three times as longas its logic '1' period.

The tester contains an integrateddecoder that detects the IR light andconverts this into a train of digital bits.This train of data is used to give an in-dication of the quality of the light sig-nals. This is based on the fact that theIR receiver will not function properlywith (very) weak signals: capturing andsynchronizing them will take longerthan with strong signals. This time dif-ference in processing gives an indica-tion of the quality of the signals.

A full description of the RC5 codingis given in Ref. 1.

Design of testerThe IR detector in the block schematicof the tester in Fig. 2 is a complete re-ceiver that is able to filter from the IRlight it receives only those signals thatare associated with IR remote control.

This is made possible by the fact thatall IR remote control systems make useof a high frequency carrier. Low -fre-quency signals are filtered out andthus do not appear in the output. Thedetector output is a TTL signal that in-dicates whether or not HF. signals arebeing received. That is, the level at theoutput varies in rhythm with the HFbursts that reach the photo diode: ahigh level means there is no h.f. signal,while a low level indicates that an HFsignal is present.

The tester works on the principlethat the pulses used in the test are

14 bit times

--------------------

-4 24.889 rive

k64 bit tidies = 113.778 me

O

1 . 0 0 possible sup*voltage drop

...,24.889 ens (14 bite

= 6 9 444 pa

!4-

O

4- 3 t32 x 4 =888 88 u (Le 6611)

910137 15

Fig. 1. How an RC5 command is modulated.

-110.

START

IR ÷ oscillatordetect

frfI RESET

RESET

STOP

counter

OK

decoder

overflow

display

*11940084-12

Fig. 2. Block diagram of the remote control tester.


INFRA -RED REMOTE CONTROL TESTER 19

identical. However, not only does thepulse train depend on which button ispressed on the transmitter, but thecode varies even when the same buttonis pressed twice in succession. Fortu-nately, the header of each instructionis constant, and this is, therefore, usedin the tester.

Even then, there is a slight diffi-culty: in some protocols the first bit isrelatively long to enable the transmitterand receiver to synchronize. Because ofthis, the variation in length caused by

poor communication is very small, sothat it gives no, or very little, idea ofthe quality of the signals. To bypassthis difficulty, the tester has a change-over switch that enables either the firstor the second bit to be selected.

Immediately a pulse train is re-ceived, the tester starts an oscillator.The number of pulses counted in thefirst (or second) bit is read, convertedand then made visible on a display (abar of LEDs).

The LED which indicates that a

pulse train has been received alsofunctions as underflow indicator. Thereis also an overflow indicator. BothLEDs are useful during the calibrationof the tester.

Circuit descriptionTo some extent, the circuit, whose dia-gram is shown in Fig. 3, is based onIC1. This chip contains both the oscil-lator and counter which are of para-mount importance for measuring the

K1

.1= 0

5V

R1

0

2x1N4148

S2

RESET MI0

I47p

P1 R5

100k

100k

D11

CTR14

IC1

9

10

11

S1

12 ts

!

CXG

RX

RCX

CT=0

74HCT4060

CT I

5

6

7

8

9

11

12

13

1

2

6 3

14 6

13 4r\

15 51\

10

R

>C

IC3b

13

12

4

R3

0

R6

if >cIC3a

0

2

0

7

DX

IC2

74HCT138

3

4

5

6

D13

R7

0

D1

4 D2

3 D3 -110.-IIP.

-I.2 D4 -I.

\11-IIII.

D7 -MP-D.

g

H R8 D9

D12 41,-1 100Q

2x1N4148

IC3 = 4013

R9 D14

3300

SFH505A SFH506 IS1 U60

<1

Sla <2

Sla <3

S11342'

Sib <3

IC1 IC2 IC3100n A 100n A 100n

1111111111111

940084-11

Fig. 3. Circuit diagram of the remote control unit tester.


20 AUDIO & HI-FI

pulse periods.The integrated IR photo

diode is connected to K1. Thedigital code converted from theincoming IR signals is appliedto pinl. A high logic level atthis pin, applied to transistorT1 via D2 and potential dividerR2 -R3, causes the transistor toconduct. This results in theoscillator input (pin 11) of IC1being connected to earth

The two bistables (flip-flops)in IC3 determine which pulsewill be measured. After a reset,the Q output (pin 1) of IC3, islow and that of IC3b (pin13) ishigh. The leading edge of thedigital input signal gives bothbistables a clock pulse, on thereceipt of the leading edge ofwhich the level at pin 5 of IC3is read and applied to pin 1.After the first clock pulse, pin1 is high because pin is linkedto the +5 V line. Diode D14then lights to indicate that thefirst data pulse has been re-ceived. Pin 13 is kept low be -

411

4. k

cause pin 9 is held low bypin 1 at the instant the leading edge ofthe clock pulse is received. When thesecond clock pulse is received, pin 9also goes high, so that from the thirdclock pulse onward both Q outputs arehigh.

The oscillator and counter in IC1 op-erate only when transistor T1 is off.This is the case only when the anodesof D10 and D11 are low. As far as D10 isconcerned, this is so every time a pulsearrives at pin 1 of K1. In the case ofD11, it depends on the position ofjumper Si. The transistor is off duringthe first data pulse with the jumper inposition A, and during the second datapulse with S1 in position B. During allsubsequent data pulses, the transistorconducts. In the timing diagram inFig. 3, signals 2 and 3 (Sia) are rele-vant when Si is in position A, and sig-nals 2 and 3 (Sib) when the jumper isin position B.

Only outputs Q4 -Q9 of the counterare used. Pins 4. 5 and 6 are linked tothe three inputs of 3 -to -8 converterIC2. This chip is enabled when pin 14of ICI is high and pins 13 and 15 arelow. This condition is indicated by oneof diodes D 1-D8 lighting. This arrange-ment means that measurements takeplace only during the second half ofthe period of the data pulse. Pulsesthat are shorter than half of their origi-nal duration are so mutilated that theyare unusable. If more than eight clockpulses occur during half the period,the clock frequency is too high and anoverflow takes place, whereupon D9lights. Either pin 13 or pin 14 or bothare then high. This results in IC2 beingdisabled and none of Di -D8 lights. The

oscillator frequency, which is deter-mined by R5, C2 and P1, can be loweredwith P1 to ensure that the requisitenumber of pulses happen during themeasurement period.

Three different types of photo diodemay be used: the pinouts of all threeare given in Fig. 3.

Power is obtained from a 9 V.250 mA mains adaptor whose output isregulated by IC4. The circuit is pro-tected against incorrect connection ofthe mains adaptor by D15.

ConstructionThe tester is intended to be built on theprinted -circuit board shown in Fig. 4.

N940084-11771

eK2

cc

0

D9

as

D6E

05')

Mg,D2p

D1

,./11 D14

s2

0.0.101C4C6

01 R6 10

of F13 10

-1'1 O{_ D16 I 10 C5

_C4 0110 C2

LINI) 01 RS loof R4 10

1C2

I COI I EMI

R8 0

As usual, commence by solder-ing the five wire bridge inplace, followed by the smallercomponents. The design of theboard allows the use of eithera digitast switch or a dataswitch. These are slightlydearer than a standard pushbutton type, but they are morereliable and are easily fitted.

The photo diode is solderedto the holes marked K1: pin 1must go the hole nearest theslanting line of the symbol.

AlignmentWhen the board is finished,connect the mains adaptor toit and set Pi to maximum re-sistance: the oscillator thengenerates its lowest frequency.Set jumper Si to position A.When the reset is pressed, allLEDs should be off. Press onebutton on the remote controltransmitter, whereupon atleast D14 should light. (It is ad-visable to fit new batteries inthe remote control transmitter

before calibrating the tester). If it doesnot, check the power supply and theposition of Si.

If D14 lights, one of D1 -D9 will alsolight. If D9 lights or flickers, there is anoverflow. In that case, set Si to posi-tion B, reset the tester and press one ofthe buttons on the remote controltransmitter. If this does not result inD14 going out. reset Si to position Aand replace C2 by a 470pF capacitor. Ifthis still does not work. there is almostcertainly a defect in the circuit, whichcan only be found by careful checkingand rechecking.

Assuming that all works well, holdthe tester near the transmitter and ad-just P1 until D7 or D8 lights. Holding

P1

I EMI

7> 07: .07

IC1 IC3

or R1 10

Fig. 4. Printed circuit board for the remote control unit tester.



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the tester at greater and greater dis-tances from the transmitter will causedifferent LEDs to light: this proves thatthe tester operates correctly. If it givesvarying results, set S1 to position B.

Finally, bear in mind to press thereset button before each measurement.

Parts list

Resistors:RI, R8 = 100 1R2, R3 R4 = 100 IcS2R5 = 4.7 IcS2R6= 10 1c12R7 = 470 Q

= 330 S2

P1 = 100 kS2 preset

Capacitors:C1 = 100 pF, 10 VC2 = 47 pFC3, C4*, C6, C7 = 100 nFC5 = =100 pF, 25 V* see text

Semiconductors:D1-D9, D14 = LED, redD10 -D13 = 1N4148D15 = 1N4002T1 = BC547BK1 = Photo diode, SFH505, SFH506-36

or IS1U60

Integrated circuits:ICI = 74HCT4060IC2 = 74HCT138IC = 4013IC4 = 7805

Miscellaneous:K2 = mains adaptor connectorS1 = jumperS2 = digitast, data switch or push

button switchPCB Ref. 940084

[940084]

Ref. 1: Elektor Electronics, January1992, p. 60


COMPUTER PSU MONITORDesign by K. Walraven

A circuit is described for continuously monitoring the variouspower supply lines in computers. It will also detect spikes

(other than RF.) on these lines.

Mie monitor checks that the ±5 Vnd ± 12 V supply voltages to a

computer are within ±5% of their nom-inal value. It will also detect spikes of acouple of hundreds of nanoseconds,but its operational amplifiers are tooslow to detect RF interference.

The circuit is housed on a card thatis intended to be inserted into one ofthe free ports of the computer. This

has the advantage that it is always pre-sent and that the voltages are moni-tored close to the computer's motherboard.

Each supply voltage may be too low,all right, or too high. Each of thesestates is indicated by an LED. The allright state has a fourth LED which hasa memory that registers whether the allright LED has been off at least once

after a system reset. If so, there is aspike on the supply line.

The LEDs and the reset control maybe brought to the front panel via alength of ribbon cable to enable moni-toring to take place at the front ratherthan at the rear of the computer. Theboard has been designed to make thisa simple modification.

Detector/indicator circuitThe circuit of the monitor ( Fig. 1) con-sists of four similar detector circuits, apower supply and 16 indicator LEDs.

To keep the circuit simple, thesupply voltages to be monitored arebrought down to a standard level of1.25 V. Reference potentials REF+ andREF- are symmetrically centred on thisstandard voltage; they differ from it bya margin that is preset with P1. Withcomponent values as specified, thismargin is 0-10%.

IOWR

IORD

RESET

OSC

CLK

ALE

11302

11303

11304

1R05

1006

1807

MEMRD

MEMWR

51301

DRO2

DRO3

SACKS

DACK1

DACK2

DACK3

TIC

.12V

+5V

+5V

GND

GND

GOD

-5V

-120

F 13

0- 1430

I 1- 29

28

1

25I-24

23

1 1- 22

21

12

11

18

11- 9

16

1

19

1

17

26

15

27

9 +12V

3 +5V

I-1 29

K3

RESET RESET

12V

1=-I I -

0-I I-0-0-

, 12110

31

7 12V

1N4148

91

IC1IC2 IC3

TT

8k66

6

11

L1

115 REF+ REF -0 07

1% 1R2

1mH

43721--1%

2

IC4a

10616V

017

IC5b

5_

IC5a

IC5c

IC5d10

5V

/ C4 4105 ICE

12 °Tv

IC1d

IC1c

7

4

IC1b

IC1a

5V o E

19 I R18

5V

R14 R 3

5

4

IC2b

-1

9

12

6

IC6c

IC6d

0

D4 /

5V

89 8

IC2a2

3

5V

R4

IC2d

13

IC6b A4 6 6 D96

B1 7 7 D$ :,....

D1k

B4

6L'1\

7

134 10 10 --:89 NI _,.. R28C1 11 \/11 -.' M-41211It 4 C2 12 12 D10 -4.-

IC6d

C3 13 13 D11 16.R29

lk

CD41 '154 '15A

012 :::013 -T.

13

30

D2 16 AT -No _.. kD14 IAzmzz,z,,,,,,,, ^--:,,m R31

D3 17 17 014 y.

IC3c 04 3,...R32

91k

5V

\AA2 4

A3 5

IC1 = LM339IC2 = 74HC86IC3 = 74HCO2IC4 = TL082IC5 = LM339ICE = 74HCO2

K2 K1- -7-3 \ / 3

\ D2R25

5V

O

IC3d

04/

5V

5V

IC4

IC2c

,0

LM317L

LM317

IC3b

IC3a

ao /-

78LXX

20--N 20,

12V L2

78XX

ICE

5V

1k

826

REF+

10011

1V25+10%

REF -

Fig. 1. Circuit diagram of the PSU monitor.


COMPUTER PSU MONITOR

The +5 V and +12 V supply voltagesare reduced to 1.25 V by resistors R6,R7 and R1, R2 respectively. The -5 Vand -12 V voltages are lowered by re-sistors R11, R12 and inverter IC4a, andR16, R17 and inverter IC4b respectively,

The standard level is compared withreference voltages by two comparators,say, IC la and IC lb. If the levels corre-spond, the outputs of the comparatorsare high and the (red) LEDs connectedto the outputs remain off. Since the in -

SLIZ id

'w°Eta Id 0 va It 11 0"'

0?..Mil 2 2 \ 11 / /!11 Pc / , 11- 8.:. io14 EN wI4

Ay 4 04 . ,..

01 Via 10es,

lo

oi 6W 10

OL sod to

0-0-110

U C.)

s

0

()C.)

CNI

CC

0000 0000 0000 og

:00 :00 :00 :000000 0000 o000 000

0

00000800000 0061909061000

008000000lil iil 0 0 Ill Ii41-\ CEI

puts to the XOR gate, IC2,, followingthe opamps, are then high, the outputof the gate is low, which causes the as-sociated (green) LED to light.

The last stage of each detector cir-cuit is a bistable (flip-flop) formed bytwo NOR gates (as, for instance, IC3aand IC3b). The bistable is reset bypressing Si. A system reset of the com-puter also resets the bistable. The LEDconnected to the Q output of thebistable goes out after the reset. Diode

RHSZEI

rn S

O 9H 0

O L8 0O LEI TO

0, zap

0 0

0

O :32-0/ e-C-k_cm\113 \ Naa 0

O Wm 63EI °0 0-0 a \ .N,/-* 0 0 0 0

0o e-c\ ca

CP "C.)

10

OO

O 0O 0

0

o ce/oCM ID CM 0CM ID ID 10

OD 0ElID

IN 04 ID

0CM 0CD CM ElCM IDOP 0 ID

CM

CM

CM

CM

CM

000

00

00

e e-00000

/0 0 0

0O0

01)0

ti

T

001

D1 prevents a reset of the entire com-puter when S1 is pressed.

If the level at the set input of, say,IC3a (pin 2), goes high, possibly be-cause the supply voltage drops or risesbriefly, the bistable is set and thefourth (yellow) LED lights. The LEDstays on until the next reset. To ensurethat all bistables are reset after thecomputer has been switched on, theyare also connected to the reset circuitin the computer.

Fig. 2. Printed -circuit board for the PSU monitor. Photograph shows completed prototype.


24 COMPUTERS & MICROPROCESSOR

The 5 V power supply for the moni-tor is derived from a 12 V source regu-lated by IC8. The -5 V supply for IC4 isderived from the computer. A small in-ductor, Li or L2, as the case may be, isconnected in series with the -5 V and+12 V lines to prevent the buffer ca-pacitors in the power supply suppress-ing spikes (which would prevent thedetectors sensing them).

Regulator IC7 provides the referencevoltages. This IC has an internal refer-ence of 1.25 V, which here is presentacross R21 and R22. Since R23 and R24have the same value as R21 and R22 re-spectively, the voltage across them isalso 1.25 V. When P1 has a value of0 Q, the potential across both R21 andR24 is 1.25 V. The levels at REF+ andREF- are then the same (1.25 V). WhenPi is set to its maximum value, the po-tential across R21 and R24 is 1.13 V.The level at REF+ is then 1.37 V andthat at REF- is 1.13 V.

ConstructionThe monitor is intended to be built ona double -sided printed -circuit board asshown in Fig. 2 (which is unfortu-nately not available ready made). Asingle -sided board proved not feasible,because it would require more than 25wire bridges. The design of the boardensures that the LEDs (slightly bent)protrude outside after the board hasbeen slotted into the computer. Asmentioned earlier, the section of theboard on which the LEDs and the resetswitch are located may be cut off andbrought to the front of the computervia a length of ribbon cable termined inheaders. The cut must run in betweenKi and K2, but the cutting must ensure

that the two fixing holes for the sup-port bracket near K1 remain on theplug-in board. If this option is notused, headers K1 and K2 are not re-quired.

When the board has been finished,the monitor is ready for use after Pihas been adjusted as desired. Nor-mally, the circuits work correctly witha tolerance of 5%, which is set as fol-lows. After the board has been insertedinto the computer and this has beenswitched on, connect a digital multime-ter between earth and pin 4 of IC5 andadjust P1 for a meter reading of 1.19 V.The potential at pin 7 of IC5 shouldthen be 1.31 V. If setting these valuesis not possible, the LM317 used is notsufficiently accurate. In that case, re-place it by an LT117 from LinearTechnology which has a tolerance ofonly 1%.

Note that if the set limits are tight, itmay happen that after Si has beenpressed, the yellow LEDs seem to stayon. This is caused by brief supply volt-age variations that occur regularly incomputers. The reaction of the redLEDs is so fleeting that it appears as ifthey remain off. Provided the computerfunctions properly, it is advisable insuch a case to set the limits with Pirather wider.

Parts list

Resistors:RI = 8.66 k52, 1%R2, R7 = 1 kS2, 1%R3 -R5, R8, Rg, R13, R14, R18,

R19 = 10 IcQR6 = 3.01 kS2, 1%R11 = 13.3 IcQ, 1%R12, R17 = 3.32 kit, 1%

R16 = 31.6 kfl, 1%R21, R24 = 221 SI, 1%R22, R23 = 49.9 Q, 1%R25 -R32 = 1 kQPi = 100 Q preset, vertical

Capacitors:Ci-C4 = 10 pF, 16 V, radialC5 = 100 nF

Inductors:L1, L2 = 1 mH

Semiconductors:Di = 1N 4148D2, D3, D6, D7, D10, D11, D14

D15 = LED, 3 mm, red*D4, D8, D12, D16 = LED, 3 mm, green*D5, Dg, D13, D17 = LED, 3 mm, yellow*

* high efficiency

Integrated circuits:ICI, IC5 = LM339 or LP339IC2 = 74HC86 or HCT86IC3, IC6 = 74HCO2 or HCTO2IC4 = TL082IC7 = LM317 or LM317L - see textIC8 = 7805 or 78L05

Miscellaneous:K1, K2 = 20 -pin straight box header

see textSi = press button switch with make

contactPC insertion card support bracket,

e.g.,Fisher KHPCL (see Fig. -3)or Eurodis No. Spe22833.

[940087]

28.5

16.8

N)

-D

IN)

22.5I13 j 14 0.14 14PI 14

-0-- -0-- -0- --;0-0 0-04-- 0--

06 50,3

0 5 5 5

Fig. 3. Template (1:1) of the support bracket showing how the LEDs should be fitted.


Plea.s.e mention ELEKTOR ELECTRONICS when contacting adVertisers

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26

STABLE D.C.-D.C. CONVERTERDesign by L. Lemmens

The very compact converter produces a stable 5 V directvoltage supply from an input of 2.5 V, and is thus eminently

suitable for use in portable equipment.

Battery -operated equipment thatcontains digital circuits often re-

quires a supply voltage of 5 V. If sta-bilization of the supply is required,the battery voltage needs to be atleast 6 V owing to the drop across theregulator. Standard regulators cannot be used, of course, since these re-quire an input voltage 3 V higherthan the output voltage. Even a low -drop regulator needs a voltage drop ofnot less than 0.4 V. And then there isthe recurring problem of space beinglimited to no larger than for, say, twoHP7 (AA, UM3, Mignon) batteries.There are then two ways the designercan take. One is to be satisfied with asupply of 2-3 V and design the elec-tronics accordingly. This is, however,not always possible. The other way isto use a d.c.-d.c. converter as de-scribed in this article.

In spite of its compactness, theconverter can supply 100 mA at 5 Vfrom an input of 2.5 V.

MAX660

The converter is based on an IC type

RC

OSCILLATOR

MAX660 from Maxim. It operates onthe charge pump principle and fulfilstwo functions: it can convert a posi-tive voltage into a negative one, and itcan double the voltage at its input. Itis, in fact, a pin -compatible successorto the ICL7660 with the output cur-rent uprated to 100 mA. The internalsetup of the IC is shown in Fig. 1.

The charge pump principle de-pends on the rapid charging and dis-charging of a capacitor, and this re-quires switches and an oscillator.

An oscillator is contained in theMAX660 and it is followed by a binaryscaler. The standard oscillator fre-quency of 10 kHz can be altered viapin 7. This pin is also used if an ex-ternal oscillator is employed. The in-ternal voltage regulator can be dis-abled via pin 6 if operation from avery low input voltage is desired.

The (electronic) switches areformed by four MOSFETs. Since thesubstrates of the FETs on the rightalways need a negative voltage withrespect to the source (to prevent leak-age via the substrate), a logic networkis provided. In combination with the

voltage level translator, this networkensures that the substrate is alwaysat the correct potential.

The action of the pump will be de-scribed with reference to Fig. 2, inwhich the FETs have been drawn asnormal switches. Note that the con-nections seem different from those inFig. 1; this is because here pin 5functions as ground, pin 3 as inputand pin 8 as output. Capacitor C3functions as pump, while C1 is the(external) output capacitor.

The oscillator voltage causesswitch pairs S2 -S4 and Si -S3 to beopened and closed in turn. When S2and S4 are closed, C3 is charged veryrapidly to the battery voltage. WhenS1 and S3 are closed (S2 and S4 arethen open), C3 is connected in serieswith the battery via S3. At the sametime, C1 is charged via S3 to the bat-tery voltage plus the voltage acrossC3, that is, twice the battery voltage.

Circuit descriptionThe circuit diagramis shown inFig. 3. As in Fig. 2, C1 is the outputcapacitor and C3 is the pump. Themanufacturer recommends that, toensure that the capacitors can becharged rapidly, they are of a typewith low internal impedance.Schottky diode D1 ensures that im-

Fig. 1. Block diagram of the converter. Fig. 2. Illustrating the action of the pump.


STABLE DC -DC CONVERTER

0Ett1

CII) 911

220p63V

7

D1

3

BAT82

COSC

'ClMAX660

V-LV

6

8

C1

212601

R2

R1

3

7

2

IN OUTLBI DD

1C2

MAX667LBO SET

SHDN

R3

R4

1%

0

C2

5V100mA

220w63V

R5

4

' 1%

° 0940079 - 13

mediately after switch -on C1 getscharged to almost the full batteryvoltage.

The doubled battery voltage is ap-plied to the input (pin 8) of IC2. ThisIC, which has a case identical to thatof IC1, can best be described as low -power, low -drop 5 V voltage regulator.It can handle currents of up to250 mA and drops only 150 mV at acurrent of 200 mA. At a current of100 mA, as in the present converter,the voltage drop is about 100 mV.

The level of the output voltage, U0,

can be set very accurately with poten-tial divider R4 -R5. Since the internalreference potential, Uref, of the IC is1.255 V (which is available at pin 6),

Uo = (R4+R5)/R5x Uref [V].

The MAX667 has a low -batteryinput (pin 3). The potential at this pinis compared with Uref. If it is lowerthan the reference, the low batteryoutput (pin 7) goes low and this levelmay be used to control an indicator,for instance, an LED. If pin 7 is con-

nected to a 10 kS2 pull-up resistor, itslevel may be used to drive a suitableCMOS circuit.

The input to pin 3 is derived fromthe battery via potential divider R1 -R2.Since the divider ratio is 1:1, a lowbattery indication will be given whenthe battery voltage drops below2.51 V (that is, 2xUref). If the low bat-tery option is not needed, R1 and R2may 4mply be omitted.

Resistor R3 ensures that the out-put voltage is cut off when the dropacross IC2 becomes too low for goodregulation.

ConstructionThe converter may be built on theprinted -circuit board shown in Fig. 4(which is not available ready made) oron a piece of prototyping board.

Once the board has been finished,it is merely a matter of connecting theinput voltage and checking with amultimeter that the output voltage is5 V. It is advisable to recheck the out-put voltage with a 100 S-2 resistor con-

nected in parallel with the meter.Although it is unlikely that the

converter will not work properly, it isadvisable to check first whether theregulator or the voltage doubler is atfault. To this end, measure the volt-age across C1; if this is equal to twicethe battery voltage, IC1 fucntions cor-rectly.

In theory, the converter works sat-isfactorily with input voltages be-tween 2.51 V and 5.5 V. A batteryvoltage of 5.5 V means that a voltageof 11 V is applied to the regulator, sothat this must 'lose' 6 V. At a currentof 100 mA, this means a dissipationof 600 mW, which is about the maxi-mum the MAX667 can handle. It isthus advisable not to use such highbattery voltages. In any case, is itsensible to double a battery voltage of5.5 V and then regulate it down to5 V?

Parts list

Resistors:R1, R2 = 1 MQR3 = 100 kS2R4= 619 kS2, 1%R5 = 200 kf2, 1%

Capacitors:CI = 220 pF, 16VC2, C3 = 220 pF, 63 V

Semiconductors:D 1 = BAT82

Integrated circuits:IC1 = MAX660 (CPA or EPA)IC2 = MAX667 (CPA or EPA)

[940079]

Fig. 4. Printed circuit board of the converter; at the right, the completed prototype.


28

PPLI Ti N N TEThe content of this note is based on information received from manufacturers in the electrical

and electronics industries, or their representatives, and does not imply practical experience byElektor Electronics or its consultants.

VOICE SCRAMBLERS FX118 AND PCD4440

nwing to the vast increase in the numberV of mobile telephones, there is an equallyvast demand (and need) for means of mak-ing listening to third -party telephone con-versations impossible, or at least difficult. Twosuch means are introduced here; both are com-pact and require only low power. One is basedon the Type FX118 IC from ConsumerMicrocircuits Ltd (CML) in England and theother is the PCD4440 from Philips of Holland,which is programmable via an I2C bus.

Both ICs use the principle of frequency in-version. In this, the frequency band of 300-3000(or 3500) Hz is inverted so that low fre-quencies become high and vice versa. Wherethe FX118 provides a simple inversion of theband, the PCD4440 is more sophisticated. ThisIC splits the speech band into two at a pro-grammed frequency and then inverts bothparts independently. Since the programmedfrequency can have any one of nine values,this chip offers good protection against eaves-droppers. Even higher protection is possibleif the programmed frequencies in the trans -

By G. Kleine

FX118 PCD4440

Function

Number of speech channels

Power supply

Current drain

Input impedance

Output impedance

Frequency range

Transfer gain

Spurious signal attenuation

Programmable

Clock

Packaging

Speech -band scrambler

Scrambler and descrambler

3-5.5 V (typ. 3.75 V)

4 mA (typ.)

10 MQ (typ.)

200 Q (typ.)

300-3000 Hz

0.5 dB (opamp gain = 0 dB)

dB

No

internal 4.433619 (same crystal

as colour TV receiver)

FX118DW: 16 pin SOIC

FX118P: 16 pin DIL

Split frequency speech band

scrambler

Scrambler or descrambler

2.8-6.0 V (typ. 5.0 V)

Typ. 13 mA (muted: 2.2 mA)

Typ. 120 Id2

<1 Id2

300-3500 Hz

0 dB (transparent mode: -3.5 dB)

dB

Via 12C bus

External, 3.579 MHz

8 pin SOIC

Table 1. Main parameters of FX118 and PCD4440 ICs.

RX IN60.600 mV

at 1 kHz rms

TX IN

60-600 mV

at 1 kHz "8

100 nF 100k

OI0-1

33pF

1114433619

MHz

11147pF

100nF 100k

VDDI2

XTAL/clock

VDD/2

LPF 1 OUT

111 kHz

111 kHz

LPF 20U

MOD1 IN FX 118

kH

111kHz

1pF

MOD 1 OUT 111 kHz

VDD

VDD/2

MOD 2 OUT 111 kHz

MOD 2 INn.c.

out

out

_940013.11

*see text

1pF

47n

RX OUT

eg0 5V

4rna.

TX OUT

Fig. 1. Combined block and circuit diagram of the Type FX118 circuit.


VOICE SCRAMBLERS FX118 AND PCD4440 29

CIN

LPFOUT

MOD, OUT

C ,,OUT

300

300

I \3000 3300 3600

f /Hz

\ f/Hz6300 6400

3000 f/Hz

U

300

300

3000

3000

3000940013.12

t/ Hz

f/Hz

Fig. 2. Mode of operation of the FX118 (x: 1 for channel 1, 2 for channel 2).

mitter and receiver are synchronized. Theprogrammed frequency can be changed tentimes per second via the I2C bus.

The filters in both circuits are switched -capacitor (SC) types, that are aligned simplyby the application of the correct clock signalto the relevant pin on the circuit. Some par-ameters of both circuits are given in Table 1.

Frequency inverter FX118A combined block and circuit diagram of du-

plex frequency inverter Type FX118 is givenin Fig. 1. The circuit has two identical sig-nal paths for scrambling and descrambling.The central clock, controlled by a 4.431619MHz crystal, provides all internally requiredclock frequencies. The crystal has been cho-sen since it is the same as the inexpensive,easily obtainable one used in colour PAL TVreceivers.

There is an amplifier in both signal paths,whose gain can be set by an external resistor.This enables the scrambler to work with

input signals of 60-600 mV r.m.s.The input amplifier is followed by a 3100 Hz

low-pass filter. The output of the filter is ap-plied to a frequency changer, which mixes itwith a signal of 3300 Hz. This results in a sumand difference frequency band. The differ-ence signal band has the desired inversionand is filtered out by a 300-3000 Hz band-pass filter.

The other signal path which, as alreadystated, is identical can be used simultane-ously for descrambling. This is why the chipis called a duplex frequency inverter. One chan-nel scrambles the outgoing signal, while theother channel descrambles the incoming sig-nal. The mode of operation in scrambling isshown on the hand of the various signals inFig. 2a. The speech signal applied to pinCON (CiIN or C2IN) covers a frequency bandof 300 Hz to about 5000 Hz. A low-pass fil-ter removes all frequencies above 3100 Hz(LPFXOUT). The resulting signal is mixed witha signal of 3300 Hz (MODxOUT), whereuponthe original band is shifted to above 3300 Hz(sum signal). There is also a mirrored signalbelow 3300 Hz ( difference signal), which hasthe desired frequency inversion. Because ofthe choice of 3300 Hz for the mixer frequency,the difference signal lies exactly in the band300-3000 Hz. The following band-pass filterfilters the 300-3000 Hz band from the out-put signal of the mixer (the sum signal is theneliminated) - CXOUT.

Figure 2b shows how the descramblingof the scrambled signal is carried out.

Figure 3 shows the practical set-up of aradio telephone. Since each FX188 IC pro-vides two signal paths (for scrambling anddescrambling respectively), only one chip isrequired in the bases station and one in thehandheld unit: full duplex operation.

AF amplifier Deem phaals

Microphonepreamplifier

Transmit/receive switch

RX OUT RX IN

FX118

Voice -Scrambler (I)

TX IN TX OUT

M -Demodulator

Frontend

HF

ZF

vosemse

FM -Demodulator

RF output stage

Frontend

ZF

HF

-IN-

'1111111111111.Preemphasis FM -Modulator

FM -Modulator Preemphasis

RX IN RX OUT

FX118

VoiceScrambler (II)

TX OUT TX IN

RF output stage

Deemphasis AF amplifier

AF amplifier

Transmit/receive switch

Connection totelephone network

940013-13

Fig. 3. Typical application of the Type FX118 circuit.


30 APPLICATION NOTE

r

100 nF I

0-1

typ. 880 mVrms

3,58 MHz

IN

f3C

fsc fmlfrn2

10 nF I f3SC1 # 4CLOCKS

L

fsc

3500 Hz

fml=fs+300Hz

f=fs+3500Hz

6

fe

lac

faC

3500 Hz

I transparent

PCD 4440

3500 Hzvemeesamm..

!Mute

* see text

I2C-Interface

'Sc

111...

SCL

r.

I2C

uTi

SDA AO0940013-14

VDD

1IJF

Fig. 4. Combined block and circuit diagram of the Type PCD4440 voice scrambler.

Communication is over two channels anduses frequency modulation. Noise suppres-sion is effected by preamphasis at the trans-mitter and deemphasis at the receiver. Highfrequencies are amplified in the preempha-sis network and attenuated again by thedeemphasis network. Since in FM demod-fulation the signal-to-noise ratio deterio-rates with higher modulation frequencies,the preamphasis and demphasis networksensure a level ratio.

Voice scrambler PCD4440The PCD4440 chip, whose block and circuitdiagram is shown in Fig. 4, provides only oneaudio channel. It uses split -frequency oper-ation, in which the speech frequency bandis split at a programmable frequency,fs, afterwhich the two parts are inverted separately.This does, of course, give a higher degree ofprotection than attainable with the FX118.If then fs is changed a number of times persecond, it becomes virtually impossible to eaves-drop on the communication. Programmingof one of up to nine possible frequencies, A,takes place via an I2C bus. The chip also hasthe facilities to pass the speech band trans-parently, that is, without scrambling and tomute the output. For duplex operation, twoPCD4440 chips are needed in both the receiverand the transmitter.

The input (Fig. 5 Cu ) is applied to a low-pass filter, whose output is split over twosignal paths. The upper path in Fig. 4 processesthe frequency band below fs. This band is fil-tered out by a low-pass section whose cut-off frequency is A. This range of signals(Fig. 5O) is applied to a frequency changer

where it is mixed with a signal, Ad. (=fs+300 Hz)(Fig. 5 Z). The resulting (inverted) signal(Fig. 5 (D) is passed through a further low-pass filter to ensure that any residual spu-rious signals are eliminated.

The upper part of ther speech band is ap-plied to a low-pass filter in the lower signalpath in Fig. 4, which has a cut-off frequencyof 3500 Hz (Fig. 5 C)). Thereupon it is appliedto a frequency changer where it is mixed

with a signal, fm2 (=f0-3500 Hz) (Fig. 5 (D).The resulting signal is passed through alow-pass section which has a cut-off fre-quency of 3500 Hz (Fig.5 )).

The two (inverted) signals (Fig. 5 ED) arethen applied to yet another low-pass filter(cut-off frequency = 3500 Hz) and amplified.

In the transparent mode of operation,the upper signal path is disabled and the fre-quency changer in the lower path is by -

G

300 is

I :

300 is

3500fo.

f/Hz

3500

hil!(.1 I300 fs 3500

300 Hz + ly

k300 fs

i/Hzi

f/Hz

3500 f/Hz

300

G

300 is 3500

fm' 2 = 3500 Hz +f.

300 fs 3500

f/Hzs.

f/Hz

f/Hzi.

940013-1S

Fig. 5. Mode of operation of the PCD4440.


VOICE SCRAMBLERS FC118 AND PCD4440

MINI I/O card for Casio FX850/880P

IF AN ADVERTIS WRONG, WHOPUTS IT RIGHT?

We do.

The Advertising Standards Authority

ensures advertisements meet with the

strict Code of Advertising Practice.

So If you question an advertiser, they

have to answer Lo us.

rlb find out more about

the ASA. please write 10

Advertising StandardsAuthority. Department X.Brook II o use , Torrington

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AV

SAThis space Is donal ed In the Interests of high standards

In driverlisernents.

The 'Mini I/O card for the CasioFX850 / 880P', which was published inour March 1994 issue (page 50), neededa communication program, 'Casio FX850PCommunication Utility Version 1.2'.This program was advertised as beingavailable on a floppy disk, Ref. 1921. Itwas purchased by us as original workfrom a Mr G.J. Klasens, who signed therelevant Assignment of Copyright ac-cordingly. However, on publication ofthe March issue, it transpired that theprogram had not been written by Mr.Klasens, but was the intellectual prop-erty of a Mr P. M. F. Paulissen. Mr. Klasenshad merely added his name to the pro-gram and offered it as his own intellectualproperty.

Since software is an intellectual prop-erty which is protected by law in manycountries (in UK: Copyright, Designsand Patents Act 1988, Section 56), alegal argument arose between MessrsPaulissen and Klasens, pending theoutcome of which Elektor Electronics(Publishing) could not offer the pro-gram for sale.

The argument has now been resolvedand we can advise readers that the pro-gram is available again under Ref. No.1921. Readers who have a copy of theoriginal floppy disk containing the nowillegal version of the program are askedto return this to our Dorchester Office,whereupon they will be sent the new ver-sion of the program.

passed. This ensures that the input signalappears in unchanged form at the output. Itis, however, passed through two low-pass

sections which remove any residual signalsabove 3500 Hz.

In muted operation, the output signal isswitched off.

The PCD4440 is programmed asfollows. Figure 6 shows two signals,

Function fs (HZ) D3 D2 D1 D0

Mute 0 0 0 1

2461 0 0 1 0

1853 0 0 1 1

1507 0 1 0 0

1279 0 1 0 1

1117 0 1 1 0

1018 0 1 1 1

899 1 0 0 0

837 1 0 0 1

767 1 0 1 0

Transparent 1 0 1 1

Start descramble/scramble mode

1 1 1 1

Table 2. Programming of the PCD4440.

SCL and SDA, which represent theI2C bus. SCL is a clock line that is dri-ven continuously by the 12C transmitter.SDA is the directional data line thatis driven by the transmitter or the re-ceiver. In principle, both I2C partiescan pull these lines to ground to ob-viate any short-circuits caused by si-multaneous drives. As shown in Fig. 7,both lines must be connected to the+5 V supply via external pull-up re-sistors.

Figure 7 also shows how thePCD4440 is clocked. There is no fa-cility to clock the PCD4440 via an in-dependent crystal. It can, of course,be clocked by an independent, ex-ternal quartz crystal oscillator.

The control via the I2C bus is alwaysby an address followed by one or moredata words. Receipt of each of thesewords is confirmed by the receiver

SCL

SDA

Start Cond.

SCL

I r-

AO RPTI.7.01 Ack.

SDA

COI CM CM CI0 0 0 0 D3 D2 01 DO DO Ack. i Stop Cond.

940013-16

via an acknowledge pulse. This indicatesthat the PCD4440 has pulled the SDA linelow while the controller generates the SCLclock pulse. Each I2C communication is begunwith a start state and ends with a stop state.

The start state (SDA goes low before SCL)is followed by the address of the PCD4440.Depending on the level at pin 8, this is1101110 (A0 = 0 V) or 1101111 (A0= 1). Theseaddresses are individually allocated to thePCD4440, so that the chip can be combinedwith other ICs that are controlled via I2C.

The R/W (read/write) bit that follows theaddress is set to write (R/W = 0).

The acknowledge pulse is followed by asingle data word. This data word containsfour bits, D3-D0, which set the split fre-quency, fs, as well as the special modes-seeTable 2. After f's has been programmed, thePCD4440 must be enabled by the start in-struction (OF hex).

SummaryBoth the FX118 and the PCD4440 circuitsenable protection circuits to be designed formobile telephones or other speech commu-nication systems. Because of the use of switchedcapacitor (SC) filters, such circuits can be keptvery compact; they need no alignment.

(9400131

+5V +5V

Px y

Px.z

3,58 MHz

SDA PCD

SCL4440

OSCI

Fig. 6. I2C control of the PCD4440.


Fig. 7. Linking the PCD4440 to amicrocontroller

IN -CAR AUDIO AMPLIFIER - PART 1

Design by T. Giesberts

The in -car audio amplifier is intended for public -minded driverswho not only love their in -car music, but also their hearing (andthat of others), which is why they keep the volume of the car'saudio system at reasonable volume levels - particularly whenthe car's windows are open. It is a sad fact that there are some

unthinking drivers who do not realise that by having the volumefully up (or nearly so) they are destroying their hearing in a fairlyshort time (and at the same time, they are a public nuisance). By

leaving the volume of your car's audio system at reasonablelevels, you will be able to go on listening to your favourite in -car

music long after the unthinking few have realised - sadly, toolate - that all they can hear is a rushing in their ears - no more.

e aspect of an in -car audio ampli-fier that makes it so expensive is

not the amplifier itself, but the powersupply. In domestic or industrial am-plifiers, it is possible to obtain anysupply voltage we wish from the mains.In a car, however, there is only a 12 Vbattery and that puts severe limits onthe amplifier's power requirements.Roughly, the output power of an ampli-fier, P, is P = Upp2/81k, where Up is thepeak -to -peak supply voltage and RL isthe loudspeaker impedance. Even with4 Q loudspeakers and a battery voltageof 13.8 V, the peak power is just about6 W. A bridge amplifier might increasethis to about 20 W. Lowering the loadimpedance to 2 Q by shunting loud-speakers, can double this figure to40 W, but that is all. The only way ofobtaining output powers of 100-200 Winto 4 SI is increasing the on -boardvoltage by a suitable d.c.-d.c. con-verter, which is the solution chosen forthe present amplifier. The amplifierproper will be described this monthand the converter next month.

Design considerationsThe design of an in -car amplifier israther different from that of a domesticpower amplifier. This is because in thelatter the major requirement is the bestpossible sound quality, which, to mosthi-fi enthusiasts means very low dis-tortion, high signal-to-noise ratio and ahigh slew -rate. In an in -car poweramplifier, the main requirements arereliability, solidity, electrical and ther-mal stability, compactness, and, ofcourse, good sound quality.

Other differences in the design of anin -car amplifier compared with that ofa domestic amplifier are sensors for

protection against a short-circuit of theoutput, too high temperatures and di-rect voltages at the output. Because ofthe inevitable high ambient tempera-tures in a car, the cooling of the heatsink mounted output transistors is en-sured by an electric fan. Moreover, theoutput transistors are of a type thatcan withstand very low loads - down to1 Q. Nevertheless, the over -currentprotection circuit comes into operationat full drive when the load drops below3 Q.

Circuit descriptionBasically, the amplifier consists of a

voltage amplifying section, T1 -T10, anda current amplifying section, T11 -T18(see Fig. 2). The section around T19 -T22forms part of the protection circuits.

The signal from the (existing) carradio is applied to the amplifier via C1.This capacitor is the only one in thesignal path and it is, therefore, a good -quality (polypropylene) type. From C1,the signal passes through a low-passfilter, R2 -C2, which limits the band-width of the signal to a reasonable,practical value.

The input amplifier is a differentialone formed by Tia and Tib. The type oftransistor used, a MAT02, ensures op-timum symmetry and minimal drift.The bandwidth is further limited byR8 -C3. R10 -C4 is a feedback network.

Zener diodes D1 and D2 protect T1against too high a collector -emitter po-tential and thus to a needlessly largedissipation.

The d.c. setting of the differentialamplifier is provided by current sourceT2. To ensure the highest possible sta-bility, reference diode D4 is thermallycoupled to T2. The current through thediode is held steady by current sourceT3. It is important that the drop acrossD4 is exactly 1.8 V, since this ensuresthe correct level of current through T1,and thus the voltage drop (3.3 V)across R6 and R7. If the drop across D4is not exactly 1.8 V, the d.c. setting can

Fig. 1. Completed (mono) prototype amplifier (fan not shown).


IN -CAR AUDIO AMPLIFIER - PART 1 al

COco

x u.)4zrCsi

03

C0

-

cD

co

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Z ZZ50

InNIt

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a, ,

T59(8

Z59Z9

oco

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?5099

I.T589

W LZ

O 0 0 0 0 0 0O 0 0 0 0 0 0

cy,

CSOLZCC

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625E

0F_D

.:,- . > 05 F- 2

co

NLL

2SOLV

T5(91.

to

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(1)

is

Fig. 2. Circuit diagram of the in -car audio amplifier.


34 AUDIO & HI-FI

be corrected by (empirically)altering the value of R15slightly.

Current source T3 alsoholds the voltage across D3constant at 1.8 V. Thisdiode serves as reference forcurrent source T5 and isalso part of another currentsource, T6. It is, therefore,thermally coupled to bothtransistors.

Current source T5 en-sures that the bias currentfor T1 is held at a steadylevel. It also provides, withR12 and P1, a d.c. offset con-trol.

Current source T6 pro-vides the d.c. operatingpoint of differential ampli-fier T7 -T8. This amplifier isaugmented by current mir-ror T6 -T10 to ensure a sym-metrical drive to the currentamplifier. Capacitor C5 pro-vides frequency correction.

The current amplifierconsists of two complemen-tary emitter followers, T13and T14, and parallel -con-nected power stages T15 -T16(n -p -n) and T17 -T18 (p -n -p).Variable `zener diode'T11 -T12 provides precisecontrol of the voltage acrossT13 -T18 and R33 -R36. Thisvoltage determines the qui-escent current through thepower transistors. Transis-tors T11 -T18 are mounted ona common heat sink to en-sure good thermal coupling,so that the quiescent cur-rent remains stable evenwith rising temperature.

The level of the quiescentcurrent (100 mA per tran-sistor) enables the amplifierto process small signals inClass A (0.3 W into 4 SI).

Capacitors C13 and C14ensure sufficient spare cur-rent during short signalpeaks.

Boucherot networkR37 -C7 at the output en-sures that the amplifier isloaded even at very high fre-quencies.

Inductor L1 limits cur-rent peaks that ensue withhighly capacitive outputloads.

ProtectionThe supply to the amplifierconsists of two differentsymmetrical voltages: ±43 Vfor the current amplifierand ±46.6 V for the voltage

T1Sfit 01.11t

Ci3

T5 11210 C5

16 Cv

++

0-0

R130

"r T4

C

F_/

R20

P1

O

cc

R30

T16

" R34 "

R33

R28 0-**

R25 .-EptTB

P26

C12

el WRua,

1203©4cio T2a

T12 T11 114ruk

R31

T10

9120

n22 Tig

T17,

K1

O 0CB E

I-C7i 0 11217111117711 000,000 00 00 0 0 00 0 0 0 00 RATS/

0 0 O0 o o

oO o

do

Oa 0 °NMI!O 0 0 0 00

0 _ 0 0

009 Ogg 0 0

O 6 0 0 0 000

O °O 0000 0

/000 0 0 00

O 0 0 0 0 00 0 Iggliggg.0 0 0cm 0 0 o 0 0AN e 0 0 0

O -0 ar- o o o

,44

0 0 0 0O

0 0 o ocm as

0 0 oIED

O 00 0 0000000

Lo]

Fig. 3. Printed circuit board for the in -car audio amplifier (2 needed for stereoversion).


IN -CAR AUDIO AMPLIFIER - PART I raAUDIO PRECISION DEFAULT THD+N(%) vs FREQ(Hz) 31 MAY 9412:44:03

1

0.1

0.010

0.005

Ap

20 100 1k 10k 20k

940078 -13

Fig. 4. Harmonic distortion vs frequency characteristic.

amplifier. The slightly higher supply tothe voltage amplifier compensates forthe inevitable drops, so that the cur-rent amplifier can be driven to its max-imum supply voltage.

The supply voltages are generatedby the converter to be described, to-gether with the complete protection cir-cuits, in Part 2. The sensors for theprotection circuits are, however, lo-cated on the amplifier board, and thesewill be briefly discussed here.

In parallel with the emitter resistorsof T16 and T17 is a potential divider,R38 -R39, which controls optoisolatorIC1. When the amplifier is overdriven,or the load drops below 3 Q, or the out-put is short-circuited, the output cur-rent rises above 13.5 A, whereupon

the drop across R38 will cause the op-toisolator to conduct.

The circuit based on T19 -T20 controlsoptoisolator IC2, which is coupled tothe amplifier output via R40. When adirect voltage exceeding ±1 V appearson the amplifier output, the optoisola-tor will be switched on: by T20 whenthe direct voltage is positive, and byT19 when the direct voltage is negative.

Transistor T23 is a temperaturemonitor.

The three sensor outputs are takento the protection circuit via box headerKI. When one of the three sensors isactuated, the associated protection cir-cuit deenergizes relay Re1, which there-upon disconnects the loudspeakerfrom the amplifier output.

The protection circuits are electri-cally isolated from the amplifier to pre-vent the converter causing possibleearth loops between them and thesource (car radio)

ConstructionThe amplifier is best built on the

(double -sided) printed -circuit board inFig. 3. Note that this board is for amono version; for a stereo version twoboards are needed.

Most resistors must be mounted up-right. Inductor L1 is self -wound. Close -wind six turns of 1.5 mm diameterenamelled copper wire on an 8 mm dia.former (e.g., a pencil). Clean both endsfor soldering and remove the former.

Diode D4 and transistor T2, as wellas transistors T5, T6 and diode D3 mustbe sandwiched together (flat side of thediodes against the transistor(s). Clampthe combinations together with a stripof copper or tin plate to ensure goodthermal coupling. Note that the LEDsmust be types that drop exactly 1.8 Vwhen the current through them is5 mA (check this with a suitable supplyand a series resistor).

The 43 V supply lines ('+', '0', '2), aswell as the loudspeaker leads, must beconnected to the board(s) via heavy-duty car -type connectors (rated at25-30 A). The 46.6 V lines (`++',Ì', and'-') carry only small currents and canthus be soldered to standard solderpins.

The heat sink on which T7 -T8 andTg-T10 are fixed (insulated with ceramicwashers and heat transfer paste) mustbe soldered at right angles to theboard(s) with the aid of solder pins (seeFig. 1).

Mount T11, T13, T15, and T17 to thetrack side of the board and T12, T14, T16

940078 - 12

Fig. 5. Template for drilling the heat sink; scale 1:1 (width = 160 mm)


36

The order forms are on page 71 this month.

COMPACT FREQUENCY METER (SEPTEMBER 1994)

Ci4

0

0

C20

Cl9r1OV

R131-1

We apologise for the inconveniencecaused to readers by the omission fromour September 1994 issue of the thirdpart of the double -sided through -platedprinted -circuit board for the 'Compactfrequency meter', which is now repro-duced on the left.

and T18 to the component side. Then,attach the board at right angles to therelevant heat sink as shown in Fig. 1and 4. Figure 4 may also be used astemplate for drilling the necessaryholes. All these transistors must be in-sulated from the heat sink with ce-ramic washers and heat transfer paste.It may be difficult or even impossible toobtain ceramic washers for T15 -T18; ifso, use mica washers. Note that thespecified heat sink allows the amplifierto provide an output of not more than120 W into 4 Q at an ambient tempera-ture of 30 °C (which is not very high ina car in summer). The full power(200 W into 4 0) can only be realisedwhen forced cooling is used.

Parts listResistors:R1, R40, R42 = 1 MQR2, R16 = 470 0R3= 10 k0R4, R5 = 3.92 0, 1%R6, R7 = 825 Q, 1%R8 = 33 QR9= 180 0R10, R43 = 3.3 k0R11 = 4.7 MOR12 = 100 k0R13, R18 = 2.7 0R14, R17 = 3.9 k4

R15 = 162 0, 1% - see textR19 = 47R20, R21 = 68.1 0, 1%R22 = 3.9 k0, 1 WR23, R24 = 121 0, 1%R25, R26- - = 22 k0R27 = 2.2 lic2

R28 = 560 0R29 -R32 = 56 0R33 -R36 = 0.22 0, 5 W, low inductanceR37 = 3.9 0, 5 WR38 = 270R39 = 68R41 = 820 k0R44 = 4.7 k0P1 = 220 (250) k4 presetP2 = 2 1(0 multiturn preset, vertical

Capacitors:C1, C15 = 2.2 pF, polypropylene, pitch

5 mmC2 = 1.5 nFC3 = 1 nFC4 = 150 pF, 160 V, polystyreneC5 = 100 pF, 160 V, polystyreneC6 = 33 pF, 160 V, polystyreneC7 = 150 nF, 160 V, polypropyleneC8, C10 = 100 pF, 10 v, radialC9, C11 = 220 pF, 63 V, radialC12 = 1 pF, polypropylene, pitch 5 mmC13, C14 = 1000 pF, 63 V, radialC16 = 100 nF

Semiconductors:D1, D2 = zener, 22 V, 1.5 WD3, D4 = LED, flat, (Udrop = 1.8 V)Tl = MATO2T2, T19, T20 = BC546BT3 = BF256CT4, T11, T23 = BD139T5, T21, T22 = BC556BT6 = BC560CT7, T8 = BF870 (BF872)T9, T10 = BF869 (BF871)T12 = BD 140T13 = MJE15030T14 = MJE15031T15, T16 = 2SC2922T17, T -18 = 2SA1216

Integrated circuits:IC1, IC2 = CNY17-2

Miscellaneous:LI = see text for winding instructionsK1 = 14 -way straight box headerRei = 12 V, car type relay with two

change -over contacts rated at 16 AFive car -type heavy-duty plug/socket

sets(plugs to be screw on type forPCB fitting)

Two off heat sink 11 K W-1 (38.1 mm)for T7 -T8 and T9 -T10

Heat sink 0.5 K W-1 (see text)Two off 12 V, 230 mA fan (Canon

CF80-T211N1D or similar)1940078-I]



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0 Mini Precision Drill12V d.c. drill with precision keyed chuck for greater

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3-9

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stock no. price each1-2 3-9

R182-663 £31.26 £28.50

Drilling/Cutting KitConsists of: 7 cutting wheels, 4 grinding wheels, 2

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1-2 3-9R182-736 £13.40 £12.30

Polishing/CleaningBrushesSteel or brass brushes in either pencil, wheel or cup

profiles. Supplied in bogs of 3.

Drive Shaft Diameter 2.4mm Nominalstock no. price each

1-2 3-9

steel brushes pencil (31

steel brushes wheel 131

steel brushes cup 131

brass brushes pencil 131

brass brushes wheel 131

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Drive Shah Diameter 2.4mm Nominal.


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Cutting Kit

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1-2 3-9

R182-758 £13.40 £12.30

Drill AccessoriesRS p.c.b. drill accessories for cuffing, cleaning and

finishing many workshop materials. The kit consists of

a 16mm dia. saw and mandrel, a felt polisher (hard),

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1-4 5-24R543-967 £7.85 £7.10

EngravingKitSimple -to -use, complete

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diamond engraving bitand 2 grinding stones.

Plastic stencil for security

marking on plastics and

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Engraving pen is also available separately with a

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R182-691 and R182-708. Spare round head 1.8mmdiameter. Diamond bits are also available separately.

engraving kitengraving pendiamond bit

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Full technical details of these products and 41,000 others inthe 3 -part Electromail Catalogue - phone for your copy now!

°Special offer price. Special offer ends 31st October 1994. Normal Price £6.50.,4

FAST DELIVERY

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24 HOUR ORDERING

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Components Ltd.

Order by phone - pay by Access or Visa - it couldn't be easier

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38

An integrated circuit is really a work of art.Particularly if you know what you can and cannot

do with it. Would you like to become an artist?Then take out a subscription to

Elektor Electronics.Write or phone to

Worldwide Subscription Service Ltd.Unit 4, Gibbs Reed Farm

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ELEL'TONICA-SThe International Electronics Magazine

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42

ELECTRONIC KNOW-HOW

By K. Schonhoff

Transformers - an overview

The development of transformers isclosely connected with the history

of alternating voltage. It was theDanish physicist Hans ChristianOersted who discovered in 1820 that acurrent -carrying conductor produces amagnetic field. Ten years later, theAmerican physicist Josef Henry discov-ered electromagnetic induction, the`conversion of magnetism into electric-ity'. In late 1831, Michael Faraday con-ducted a series of experiments with adevice that consisted of an iron toroidaround which two windings of insu-lated copper wire had been placed (seeFig. 1). He connected a battery to oneof the windings and hoped that a directvoltage would be inducted in the otherwinding. But to his surprise, even aftertwo hunded experiments, the only timethe galvanometer across winding Bdeflected was when he connected ordisconnected the battery from windingA. It was only after the French instru-ment maker, Pixii, in 1832, built ahand -operated alternating voltage gen-erator (alternator) that the transformercould be further reasearched anddeveloped.

Early researchers, who appliedalternating voltage across an induc-tance, and measured the consequentvoltage and current, discovered thatthe electrical resistance of a coilchanges when an iron rod was insertedinto it. This resistance increased fur-ther when the iron was formed into aclosed circuit. The kind of iron alsohad an effect on the resistance: thiswas greatest with soft iron (i.e, iron lowin carbon, which is unable to retainmagnetism). If a second winding wasplaced over the iron, but insulatedfrom the first winding, it was foundthat if an alternating voltage wasapplied across the first winding, analternating voltage was induced in thesecond winding. The secondary voltagewas found to be high when the windingconsisted of many turns.

Transformer coreThe iron core improves the transformeraction in two respects. Firstly, itincreases the electrical resistance ofthe winding to an applied alternatingvoltage. The current in an air -coredcoil to which an alternating voltage isapplied increases about four times as

fast as in an iron -cored coil. Secondly,the iron contains many small magnetswhich are normally so distributed thattheir actions cancel one another. Theyare, however, mobile and can be placedin such a position by an external fieldthat they magnify this field. This mag-nified field produces a much greaterself inductance.

Eddy currentsThe iron core of a transformer is anelectrical conductor. The outer periph-ery of the core forms a closed loop andacts thus just like a turn of the wind-ing. This means that a voltage isinduced across it and a current flowsthrough it. The core consists of manysuch closed loops in which small cur-rents, so-called Eddy current, flow.These currents cause power dissipa-tion (loss), which is noticeable by thewarming of the transformer duringoperation.

This power loss is minimized bymaking the core not of solid iron, butof thin wafers of steel, laminations,which are electrically insulated fromone another. Moreover, the electricalresistance of the laminations is in-creased by the addition of a smallamount of silicon to the steel.

The insulation between the lamina-tions consists of a 6-10 pm thick,single -sided layer of varnish, a 2-3 pmthick double -sided coating of phos-phate, or a 2-3 pm thick oxide coating.

The space factor, that is, the ratio ofthe active cross-sectional area to thetotal area, varies from 0.75 (laminationthickness 0.05 mm) to 0.92 (laminationthickness 0.5 mm).

Fig. 1

Primarywinding

Layer winding

Secondarywinding

Interleaved winding940046-12

Fig. 2

ElDIN 41302scrapless

0

0

0

0940046 - 13

The diameter of some common Fig. 3

Insulation Wire diameter in mm

0.1 0.5 5

enamel single 0.011 0.028 0.040 0.060

double 0.021 0.045 0.065 0.100

rayon single 0.05 0.06 0.07

double 0.09 0.11 0.12

cotton single 0.10 0.12

double 0.16 0.22 0.40

paper single 0.12 0.12 0.20

double 0.22 0.22 0.35

Table 1. Diameter of some commonly encountered winding wire.


ELECTRONIC KNOW-HOW: TRANSFORMERS

MDIN 41302

940046 - 14

MDDIN 41302

°

O

940046 - 15

Fig. 4. Fig. 5

winding wire is given in Table 1.

SaturationWhen the current through the primarywinding increases, the field strengthand the magnetization of the core alsoincrease. However, at a certain level ofcurrent, the magnetization no longerincreases: the core is saturated, butthe (weak) field around the transformerbecomes stronger. This stray field cancause interference in electronic cir-cuits. Moreover, the energy transfer tothe secondary winding deteriorates,because not all the lines of force pro-duced by the primary embrace the sec-ondary.

The stray field is particularly bother -

Fig. 8

Fig. 6

some when the primary and secondaryare relatively far from each other, ason a UI core. It is not so strong whenthe windings are adjacent on the samelimb of the core, and weaker still whenthe windings are on top of one another,as in most transformers.

Two properties of the core are par-ticularly important for computing atransformer design: the degree towhich it can be magnetized before sat-uration occurs and the permeability,that is, the degree to which it magnifiesan external field. These factors deter-mine the number of turns required fora certain voltage. The higher the mag-netizability, the fewer turns are neededin both windings. The number of turnsalso depends on the cross-sectional

Fig. 7

area of the core and the form factor ofthe transformer.

LaminationsOriginally, transformers were needed toprovide relatively high power for energysupply systems. They used a rectangu-lar core with well separated windings(see Fig. 2): this ensured good electri-cal isolation. The windings invariablyconsisted of cotton -insulated copperwire. In case of a failure, each of thewindings could be removed and re-paired or replaced.

When, later, transformers wereneeded for powering small equipment,their designs started to use so-calledshell -type cores-see Fig. 3. Shell -type

cores are sub -divided into EI,M and F types, according to

111111 111 1 1 I 1l 1111111111111Fieldstrength demand13 = f (I))

measured to DIN 50 462 f = 50Hz

Sample cut ha f parallel, half transverse to rolling direction

14

1,0

08

06

ac

02

fillV800 - 50AV700 - 50AV530 - 50AV 00 - 50AV 50 - 50AV330 - 50A ---;.:....

/

ti

V80 -50AV70 - 50A /V530 - 50AV40 - 50AV35 -50AV33 - 50A

1,4

,2

1,0

0,8

Transformer laminationsV800 50A 0,6V700 - 50AV530 - 50A

000

2 4 6 8

V400 - 50AV350 - 50AV330 - 50A

0,2

02 3 If)

10 12 14 16 18 20 22 21. 26 28 30 32 (21100 200 300 13/

Fieldstrength (max. value) H A /cm

940046-26

their shape.The EI type is particu-

larly suitable for transform-ers that need a small air gap(down to 10 pm). The out-put voltage of such trans-formers is load -dependent,which is, for instance, use-ful in battery chargers thatmust deliver a constant cur-rent. This type of trans-former is also useful inamplifiers. In a single -endedclass A output stage flows

Fig. 9


Fig. 10 Fig. 11

44 GENERAL INTEREST

Table 2. Electrical data fortransformers with M and El cores

(El=scrapless).[Laminations Type V170 -50A toDIN 41 302, Part 2 (II = 0.94)].These are but two of the many

tables contained in transformerdesign books.

Type

& size

lo.,

W T --- V A W W - -

M 42 3,94 1,37 6,7 4,31 0,68 3,81 1,365 1.76 0,467 0,416 0,89 22,6 10,8

M 55 15,8 1,38 4,97 11,6 1,78 5,7 1.267 1,301 0,68 0,61 0.89 14.1 6,4

M 65 34,1 1,39 4,1 21,5 3,25 7,6 1,228 1,188 0,76 0,69 0.9 10,2 4,45

M74 62 1,39 3,51 34,5 5,2 9,3 1,198 1,13 0,81 0,74 0,91 7,9 3,35

M 85a 82 1,37 3,47 43,2 6,9 10,4 1,189 1,111 0,83 0,76 0,92 6,8 2,8

b 108 1,33 3,31 51 9,1 10,9 1,17 1,09 0,84 0,78 0,93 6,1 2,5

M102a 143 1,42 2,94 67 10,8 13,5 1,163 1,084 0,85 0,79 0,93 5 2,02

b 198 1,31 2,76 79 14,6 14,1 1,139 1,065 0,87 0,82 0,94 4,45 1,75

Type

& size

Thermalresistance

1

-W T - V A W W - - r

M 42 4,05 1,38 6,8 4,53 0,51 3,91 1,348 1,76 0,478 0,421 0.88 22,6 10,8

M 55 16,4 1,4 5,1 12,7 1,36 6 1,262 1,301 0,69 0,61 0,88 14,1 6,4

M 65 35,7 1,42 4,21 24,4 2.5 8 1,231 1,188 r 0.77 0,68 0,88 10,2 4,45

M 74 65 1,43 3,62 40,8 4,06 9,9 1,208 1,129 0,82 0,73 0,89 7,9 3,35

M 85a 87 1,41 3,6 . 53 5,5 11,2 1,204 1,109 0,84 0,75 0,89 6,8 2,8

b 116 1.39 3,44 66 7,5 11,8 1,193 1,087 0,86 0,77 0,9 6,1 2,5

M 102a 154 1,42 3,05 86 8,7 14,6 1,184 1,083 0.87 0,78 r 0,9 5 2,02

b 215 1,39 2,87 111 12,4 15,2 1,169 1,062 0,89 0,81 0,911-

4,45 1.75

7

6

5

4,

3

2

Transformer laminationsV800 - 50AV700 - 50AV530 50A-

V400 - 50AV350 - 50AV330 - 50A

magnet 'cPPE= f (B)measured according

Sample cut 1.5

Test results

reversal

parallel

and ave

loss

to DIN

and

age

50 462 f = 50Hz

1.5 transverse to rolling direction

values can not be guaranteed.

I1I

AiiiIMMIIIMM V800 50A1111111111E11111INIMIIIIMEMMEN V700 - 50A11111111115111ln=MM.

111111111 V530-5" IIIIIIIIIIIISIIII"00-5"111111111 11111q211111411

"""'" V350-5013 1111,740111111,11Torwrmkprupwrimm...................,,,

111111111 1/111011011g1111

111111111111111111111111111Q2 94 0,6 0,8 1,0 1,2 1,4 1,6

Induction B T

44

O

E

,0

0

0

(0

3,0

940046 - 24

10

7

5

4

re2 3

-8

r,

S

4 07

0,5

04

0.3

0,2

07

0.07

0.05

0,04

0.03

0.02

0,07

PS PFe

10

7

5

4

a_71'

2 §

.;

07

Transformer laminations (grain - oriented)VM111 - 35(M6 - 35)(Orsi 111 - 35)(C5 - DIN 41 302)

magnetic reversal loss: PFe. f (B)Apparent power Ps =1(6)Measured on unstressed Epstein sample accordingto DIN 50 462Frequency 50HzThickness : 0.35mmMagnetix flux parallel with rolling direction

0.5

0.4

0,3

02

-7:01

7007

70135

004

-0,03

0,02

1 1 1 1 !NI 00104 0.6 0,8 1,0 1,2 1,4 7,6 1,8

Induction B T

940046-25

Fig. 12 Fig. 13


ELECTRONIC KNOW-HOW - TRANSFORMERS 45

Fig.14

7P; 7

940046-28

Fig. 15

2

940046-29

Fig.16

U LS1

11 R1 LS1 a (-

U1

W1

Ob

U LS2 U R2

c LS2 R2 12

d

0

1U2

940046-30

z

Fig. 17

not only alternating, but also directcurrent. The air gap prevents the directcurrent pre -magnetizing the core,which then may become saturatedwhen the alternating current begins toflow or increases.

The M type cored transformer-seeFig. 4- is intended mainly for specialapplications, where its relatively strongstray field does not matter.

Capacity improvementSpecial alloys for the laminations cou-pled with particular rolling processeshave improved magnetic propertiesconsiderably. In grain -oriented corematerials, the grains are oriented bycold rolling of the material. They arealigned in the same direction as themagnetic flux established in the lami-nations. This improves the parallel, butnot the transverse, magnetizability.

In the MD core-see Fig. 5-whichmade its appearance in the 1960s, thetransverse magnetizability is also im-proved. In this core, the effect of the airgap is reduced by aligning the lamina-tion joints in the direction of minimumflux density.

The PM core-see Fig. 6-is a fur-ther enhancement of the M type. Itsimprovements include a widening ofthe outer shell compared with theinner shell, which results in a weakermagnetization of the outer limbs thanin the centre limb. Also, strengtheningof the limbs results in a smaller mag-netic resistance, so that the core cancontain more lines of force, whichreduces losses. Moreover, the arrange-ments of the laminations in layers offour-see Fig. 7-means that each airgap is flanked at either side by threeclosed loops (laminations) that act asdiversion for the lines of force (seeFig. 8). These improvements mean aneven better efficiency and weaker strayfield than obtainable with the MD core.

A few years ago, the PM core wasitself improved by a longitudinal shiftof the winding window and optimiza-tion of the air gap to raise the efficiencyby a further few per cent.

Apart from the standard types, thereare several special types from a num-ber of manufacturers, such as that inFig. 9. The manufacturer states thatthis has the same good properties ofthe PM types, but the better physicalstability of the M type.

ComputationsThe basic transformer formula is

Ui = 4.44x 10-4xBxAcxfxNi,

whereU1 = primary voltage in V;B = magnetic flux density in testa;A, = cross-sectional area of the core in

46 GENERAL INTEREST

cm2;= mains frequency;

= number of primary turns.

Assume that a transformer, operat-ing from a 240 V, 50 Hz mains supplyis required to deliver a secondary volt-age of 24 V. An M65 core (see Table 2)with a cross-sectional area of 4.9 cm2,which allows a maximum flux densityof 1.42 T and a secondary power dissi-pation of 35.7 W, will be used. Howmany primary turns will be required?

Rearranging the formula and insert-ing the specified values gives

= U1/(4.44x10-4xBxAcx,f)= 240/(4.44x10-4x1.42x4.9x50)= 1553 turns.

If the mains voltage were 250 V, theflux density would be

B = U1(4.44 x10-4x1VI xAcx Jr)=1.48 T,

which exceeds the permissible maxi-mum, so that the transformer wouldbe driven into saturation. This showsthat in these calculations the highestex-pected primary voltage must betaken into account, which includesmains variations (±5%).

The effective efficiency is read fromTable 2 as 77%. If grain -oriented Mlaminations VM 111-35 had beenused, a core of the same dimensionswould have allowed a dissipation of43 W and given an effective efficiencyof 81%.

Note in the formulas that B is in-versely proportional to the frequency.

Hysteresis

When the frequency of the primaryvoltage is increased greatly, the lossesin the core become so large that lami-nations can no longer be used. Theyare replaced by compressed iron -dustcores in which the losses are muchsmaller. Also in wide use are ferritecores, which consist of high -resistancemagnetic material consisting princi-pally of ferric oxide and one or moreother metals. After being powdered andsintered, ferrites exhibit low eddy cur-rent losses at high frequencies andthus make ideal core material for RFinductors and switching elements.Other cores for use in RF transformersand inductors are made of ferromag-netic spinels, which are high perme-able and resistive ceramic -like materi-als that exhibit very low eddy currentlosses and high permeability.

Figure 10 shows typical magnetiza-tion curves for laminated cores. Figure11 shows typical hysteresis curves oflaminated transformers.

Hysteresis is the tendency of a mag-netic material to saturate and retain

Terminal II

Terminal I

U2 max consecutive numbering

41 40 39 38 37 36 35 34 33 32 31

20 21 22 23 24 25 26 27 28 29 30

OV direction of consecutive numberingNumbering method at terminals of single-phase transformers

940046 - 31

Fig. 18

24 23

1=1

N 21

Diagram

Terminal board0 0 0 020 21 22 23 24

Manufacturer

TypeP=120W, output 5A

50Hz

Input 20-21 = 240V

Output 23-24V = 24V

Layout of terminal board Type label(only for 5 -way boards;one terminal not used)

940046-32

Fig. 19

36 35 34 33 32 31

1.11;

20 21 22 23

-Output -- Input -

Strip IDiagramConsecutive numbering

940046 - 33

36 35 34 33 32 31

00 0 0 0 0

020 21 22 23 24 25

Layout of terminalboards I and lleach with 6 terminals

0 0 0

Fig. 20

39 38 37 36 35 34 33 32

f,2 1.6.1

20 21 22 23 24 25

Diagram

31 39 38 37 36 35 34 33 32 31

0 0 0 0 0 0Strip IStrip ii

020 21 22 23 24 25 26 27 28

0 0 0

Layout of terminal board940046-34

Fig. 21

Variable ratiotransformer

UnknownTransformer

ri

940046-35

Fig. 22


ELECTRONIC KNOW-HOW - TRANSFORMERS 47

Fig. 23

some of its magnetism after the alter-nating magnetic field to which it issubjected reverses polarity, thus caus-ing magnetization to lag behind themagnetizing force. The area of the hys-teresis loop is a measure of the energyloss at each magnetic reversal. Figures12 and 13 give energy loss characteris-tics for various kinds of lamination at50 Hz. Hysteresis losses increaserapidly with rising frequency; at a fewthousand hertzs, only ferrites exhibitlow hysteresis losses.

Toroidal transformersIn toroidal transformers, the core con-sists of a single long foil of magneticmaterial that is turned into a toroid.The primary and secondary windingsare placed on to this toroid by a specialtechnique-see Fig. 14. In these trans-formers, all lines of force point in thesame direction.

The thinner the strip of magneticmaterial is, the lower the losses in theiron. Therefore, these cores are nor-mally made of very thin foil. It is hardto think of a better closed magneticloop.

Although the core is entirely sur-rounded by the windings, so that ittends to get warm, this is offset by thefact that the windings easily radiateheat. In the design of toroidal trans-formers, this property is used by allow-ing the copper losses to increase by theuse of thin wire. Therefore, the resis-tance of a toroidal transformer is largerthan that of a laminated transformerwith the same power handling.Physically, however, the toroidal trans-former is smaller.

Some theoryBasically, the operation of a trans-former depends on mutual induction.

The primary and secondary windingslie in the same magnetic flux. Thebasic design of a transformer is shownin Fig. 15; its circuit diagram inFig. 16.

An alternating current in the pri-mary gives rise to an alternating fluxwithin the core. If the current is sinu-soidal and it is assumed that the fluxis always directly proportional to thecurrent, then

= m sin 2nft

describes the variation with time of theflux. (I) is the flux at time t, Om is themaximum value of the flux and f thefrequency with which the current, andthus the flux, alternates. The inducede.m.f. per turn is given by

U. -(dO/d

= -[d(cbm sin2rcft)/d t]

= -2 nfOnicos 2nft.

The maximum value of this inducede.m.f. per turn, Um, occurs when thecosine term has its maximum value of1. Thus,

Urn = 2nf4nl.

The r.m.s. value of this e.m.f., Urms, isgiven by

Urms = Um/42 = 27cf0mh12

= 4.44f0m.

If the primary has N1 turns, ther.m.s. value of the primary e.m.f., U1, is4.44N1f4m. If the secondary has N2turns, the r.m.s. value of the secondarye.m.f., U2, is 4.44N2f0m.

The ratio IJI:U2 = N1:N2 = n is theturns (or transformation) ratio of thetransformer.

When a load is connected across thesecondary, a current /2 flows through itwhich tends to counter the change influx. This results in a lowering of thecounter-e.m.f. in the primary, so thatthe primary current, II, rises. This riseexactly counters the demagnetizingeffect of the secondary current.

So far, the resistance of the primaryand secondary windings, as well as anystray fields, have been neglected. Inpractice, the primary causes a strayflux 0,1, which is not linked to the sec-ondary. Similarly, the secondary gener-ates a stray flux, 4 s2, that is not linkedto the primary. These fluxes inducevoltages U51 and L152, which lag thestray fluxes by n/2.

It may be assumed that, since thesestray fluxes exist primarily in the air,they do not depend on the induction.The stray fluxes, and thus U51 and U52,are directly proportional to II and /2.

For our calculations, it does not matterwhether the voltages are induced in thewindings or in separate, air -coredcoils. The inductances of these imagi-nary coils are determined by

10)41 =Pc' = usifil

and

(042 =ixs2 = Us2/12.

These coils and the resistance of thewindings are shown in Fig. 17.

TerminationsTerminations on 'unknown' transform-ers that are marked by one or two rowsof figures between 20 and 99 arealmost certainly to DIN 42200. Thesenumbers contain useful information.Most good -quality transformers havetwo rows of figures: their numbering isas shown in Fig. 18:

Terminations rated up to 25 A max.row 1: starting with 20 up to 60row 2: starting with 31 up to 60Terminations rated up to 60 A max.row 1: starting with 61 up to 99row 2: starting with 71 up to 99.

For the row with primary termina-tions the following applies: start with0 V at termination 20 and then up withincreasing potential. See Fig. 19-21.

For the row with secondary termina-tions: start with the highest outputvoltage at the highest numbered termi-nation and then down with decreasingpotential. See Fig. 19-21.

The open -circuit voltage of anunknown transformer may be deter-mined with a set-up as in Fig. 22. Upto saturation of the transformer, theopen -circuit current will be small,about 5-15% of the nominally ratedcurrent. It increases in direct propor-tion to the applied voltage and sharplyso when saturation is reached asshown by the curve in Fig. 23.

Since very high voltages may arise,the testing of an 'unknown' trans-former should be carried out with greatcare and be started with relatively lowapplied potentials. The knee of thecurve in Fig. 23 is a measure of thenominally rated voltage of the winding.

[940046]


48

DESIGNING

OSCILLATORS FOR PICs

By A Rieti ens

Peripheral Interface Controllers, PICs®, from Microchipare currently in the centre of attention. In descriptions ofthese devices an important aspect is seldom mentioned:

the design of the clock oscillators. This articleaims at putting this right.

Peripheral Interface Controllerscontain a general purpose clock

oscillator. This oscillator is controlledby an RC network, a quartz crystal ora ceramic filter. The clock signal mayalso be taken from an external gener-ator. In the programming of theEPROM version of the PIC it must bestated which type of oscillator isused. The One Time Programmable(OTP) and QTP versions are availablein four different types: RC, LP, XT orHS. Each of these types is suitable forone of the four oscillator variants.

RC oscillatorsRC oscillators are an economical de-sign for those applications where ac-curacy is not too important. Whenthis oscillator is to be used, the RC orEPROM version of the PIC must bepurchased. If the EPROM variant isused, the correct bit combinationmust be selected during program-ming.

The oscillator frequency depens onfour quantities: the voltage, the tem-perature, the value of the capacitorand the value and type of the resistor.The design of the oscillator is shownin Fig. 1. Since at resistance valuesof >1 MS2 the oscillator becomes vul-nerable to noise, temperature varia-tions and humidity, it is advisable touse values of 5-100 k52. Values <3 ki2may cause instability. Table 1 gives acorrelation of the capacitance, resis-

tance and oscillator frequency. Thefrequency may be 0-4 MHz.

Quartz & ceramic oscillatorsCeramic and crystal oscillator have anumber of advantages over RC types.Especially their stability and accuracymake them very suitable for circuitsthat are to be used in a wide varietyof conditions. For this type of oscilla-tor, the XT, HS or LP version of thePIC must be purchased. The EPROMversion with accurate configurationmay also be used. The XT versionmay be used with crystal frequenciesof 0.1-4 MHz, the HS version from4 MHz to 20 MHz and the LP versionfrom d.c. to 40 kHz. If an external os-cillator is used, all these versions canoperate down to d.c.

The basic circuit of the oscillator isshown in Fig. 2. Sometimes a resistorhas to be added to suppress oscilla-tion at overtones. When the HSD ver-sion is used, Rs must always be fitted;its value should be between 100 C2and 1 kO. Table 2 gives the optimumvalues of C1 and C2 if a ceramic res-onator is used, while Table 3 givesthese values when a crystal is used.

External oscillatorIf a central clock oscillator is used inthe processor system, it is convenientif the PIC can also employ this. Theexternal clock signal must then be

RC OSCILLATOR FREQUENCYVARIATION FROM UNIT TO UNIT

Cext Rext Average

Fosc @ 5V, 25C

20pf 3,3k 4,71 Mhz ± 28%5k 3,31 Mhz ± 25%10k 1,91 Mhz ±24%100k 207,76 Khz ± 39%

100pf 3,3k 1,65 Mhz ± 18%5k 1,23 Mhz ±21%10k 711,54 Khz ± 18%100k 75,62 Khz ± 28%

300pf 3,3k 672,78 Khz ± 14%5k 489,49 Khz t 13%10k 275,73 Khz ± 13%100k 28,12 Khz ± 23%

940106 - T1

Table 1.

CAPACITOR SELECTIONFOR CERAMIC RESONATORS

OscillatorType

ResonatorFrequency

Capacitor RangeC1 = C2

XT 455 KHz 150 - 330 pF2,0 MHz 20 - 330 pF4,0 MHz 20 - 330 pF

HS 8,0 MHz 20 - 200 pF

940106-T2

Table 2.

CAPACITOR SELECTIONFOR CRYSTAL OSCILLATOR

OscType

Freq Cl C2

LP 32 KHz 15 pF 15 pF

XT 100 KHz200 KHz455 KHz

1 MHz

2 MHz4 MHz

15 - 30 pF15 - 30 pF15 - 30 pF15 - 30 pF

15 pF15 pF

200 - 300 pF100 - 200 pF15 - 100 pF15 - 30 pF

15 pF15 pF

HS 4 MHz8 MHz

20 MHz

15 pF

15 pF15 pF

15 pF

15 pF15 pF

940106 - T3

Table 3.

applied to input OSC1. Output OSC2remains unused. Only XT, HS, LP andEPROM versions of the PIC can beused for this configuration.

(9401061

Rext

Cext

Vss

VDD

-411

Fosc/4

OSC1

PIC16C5XRC

OSC2/CLKOUT

940106-11

OSC1

Cl

O XTAL

OSC2

C2

PIC16C5X,

, A- SLEEP

- - Ow TO INTERNALLOGIC

940106-12

CLOCK FROM --__EXT. SYSTEM

OPEN -of OSC2

PIC16C5X

940106-13

Figure 1. Figure 2. Figure 3.


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50

PlC® PROGRAMMING COURSE

Pi\ T 3: INSTRUCTION SET

So far in the course we have been dealing with the hardware structureof the PIC processors. This third instalment, and the one to come, willdeal with programming aspects and the PIC instruction set. Thisinstalment also introduces the MPALC assembler for PIC devices,which may be obtained on diskette.

By our editorial staff.

Source: Microchip Technology Inc.

The instructions in the in-struction set of most proces-sors usually consist of twoparts: an opcode (the in-struction proper), and anoperand (such as a memorylocation or a register). Theoperand is the object of theopcode. Most microproces-sors and microcontrollersuse one or more bytes for op -codes and operands. Not sowith the PIC16C5x proces-sors, which work with 12 -bitwide words containing theinstruction code and theoperands. This approachhas advantages as well asdisadvantages. For example,the 12 -bit structure limitsthe number of possibilitiesfor the instruction code to33. On the other hand, ithas the advantage of offeringvery fast instruction pro-cessing because all informa-tion is fetched in one go.

The instructions used bythe PIC16C5x may be di-vided into three groups:- byte oriented register file

instructions;- bit oriented register file in-

structions;- constants and control in-

structions.

A marked difference withother processors is noted asregards the byte oriented in-structions. Usually, a Work-ing register' (`W' register inPIC devices; 'accumulator' inmost others) is used, for in -

5V

R2 R3

E'D2

-M.

-O.

R4 IR5 R6

17

15:00n

14

18

2

4

C3

1076V

K1 D1

RAO

RA1

RA2 PIC16C54 RB3RA3 PIC16C56 RB4

MCLR

RTCC

RBO

RB1

Id1 RB2

OSC2/OSC1 CLKOUT

RB5

RB6

RB7

C1

16 115

a RI

C2

227 172p

X1 = 4MHz

IC2

5V

6

7

8

9

10

11

12

13

940062 - III - 11

Fig. 1. Circuit diagram of the PIC-based LED flasher.

stance, when adding twonumbers. With PIC devices,the programmer has the op-tion of storing the result intothe W register or into theregister file specified in theoperand. In the instructioncode, the choice is madewith the aid of the 'destina-tion bit', d. Unfortunately,Microchip Technology hasleft the declaration of the dbit to the programmer. Con-sequently, the 'd' bit has tobe declared as follows at thestart of every program:

W equ OH

F equ 1H

;rule destination

;destination = W

;destination = f

The PIC instruction set issummarized in Tables 1, 2and 3. The commands anddirectives used by Micro-chip's `MPALC' PIC assem-bler are listed in Tables 4,5, 6 and 7. A number ofthese will be discussed fur-ther on in this article.

For example: aflashing LEDThe outputs of a PIC16C5xprocessor can drive loads upto 20 mA. However, the max-imum current drawn by thePIC device must remainbelow 50 mA, while the cur-rent through the GND(ground) connection mustremain smaller than150 mA.

A programming example,LED_SMPL.ASM (on thecourse diskette), works inconjunction with the hard-ware arrangement shown inFig. 1. An LED and a 330-51series resistor are connectedbetween the positive supplyline (+5 V) and I/O port lineRAO. All other I/O pins arestrapped to +5 V via 10-kS2pull-up resistors. A press -key is connected betweenRA1 and ground. The circuitis built on an experimenta-tion board for PICs describedin Ref. 1.

The function of the pro-gram is simple: arrange forthe LED to start flashing as


PIC PROGRAMMING COURSE - 3 Elsoon as the press -key is ac-tuated. The example pro-gram is assembled asfollows:

MPALC LED SMPL.ASM<RETURN>

While programming the PIC,make sure that the XT(quartz crystal) oscillator op-tion is used.

The operation of the pro-gram is easily followed by re-ferring to the listing shown inFig. 2. Lines 1 through 16contain the assembler in-structions which determinethe appearance of the listing.The comment with these linesis mostly self-evident. Next,the RESET vectors are de-clared. The declarations de-pend on the controller used,and are programmed via aconstant called 'controller'. Inthe present example, 'con-troller' takes a value of 56. Inthe subsequent If...endifconstruction, a second con-stant, 'Adr_Resef is defined,which is dependent on thevalue of 'controller', andserves to enable the assem-bler to include the reset vec-tors in the proper locations.

The directive 'list p=16C' isa little unusual. Why theprocessor type is defined usinga `list' instruction will proba-bly remain a secret kept by thedesigners of the assembler.

More constants are de-clared up to line 77. Well -commented declarations areessential to get a good in-sight into the structure ofthe program, and are essen-tial for efficient program de-velopment and debugging.Also, the declarations maymake use of the assembler'scomputing capabilities, forexample,

characters/line

lines/page

characters/page

equ 80

equ 25

equ charac-

ters/line x

lines/page

This is the correct approach.By contrast, the followingdeclaration is incorrect:

characters/page equ 2000

As already mentioned withthe description of the PIChardware, a CALL instruc-tion can only 'jump' within

Table 1. Byte -oriented filo register operations

Mnemonic

operand($name, uporanon Affected

ADDWF f, d Add W and f C, DC, Z

ANDWF f, d AND W and f Z

CLRF f Clear f Z

CLRW - Clear W Z

COMF f, d Complement f Z

DECF f, d Decrement f Z

DECFSZ f, d Decrement f, Skip if zero

INCF f, d Increment f Z

INCFSZ f, d Increment f, Skip if zero

IORWF f, d Inclusive OR W and f Z

MOVF f, d Move f Z

MOVWF f Move W to f

NOP - No Operation

RLF f, d Rotate left f C

RRF f, d Rotate right f C

SUBWF f, d Subtract W from f C, DC, Z

SWAPF f, d Swap halves f

XORWF f, d Exclusive OR W and f Z

Table 2. Bit -oriented file ster operations

1......u... r ,

opetand(s)Name, operation OWIllb

Affected

BCF f, b Bit clear f

BSF f, b Bit set f

BTFSC f, b Bit Test f, Skip if Clear

BTFSS f, b Bit test f, Skip if set

[ Table 3, kihnal and control operations

Mnemonic,

operand(s)noun:, uratuani

Affected

ANDLW k AND literal and W Z

CALL k Call subroutine

CLRWD - Clear watchdog timer TO, PD

GOTO k Go To address (k = 9 bit)

IORLW k Inclusive OR Literal and W Z

MOVLW k Move Literal to W

OPTION - Load OPTION register

RETLW k Return, place Literal in W

SLEEP - Go into standby mode TO, PD

TRIS f Tristate port f

XORLW k Exclusive OR Literal and W Z

Table 4 Data directives

data <expr> Create a 12 -bit data value or character string

zero <mem units> Initialize with zero <mem units> of program space

set <label> ... <expr> Define assembler value

res <mem units> Reserve words of program space

equ <label> ... <expr> Define an assembler constant

include "<file_name>" Include a file into the assembly source flow

Table 5. Listing directives

list <option> Set various list control options

page Force a page eject

title "title text" Define a new title for the listing header

subtitl "subtitle text" Define a new subtitle for the listing header

PIC16C5xPROGRAMMING

This short course is aimedat providing an introductioninto programming andhardware aspects of thePIC16C5x family of micro -controllers manufactured byMicrochip Technology Inc

An assembler is offered ondisk in support of thecourse. This assembler isdistributed with the permis-sion of Microchip Technol-ogy Inc., and supports thePIC16C5x and PIC16Cxx se-ries of controllers It offers afull featured macro and con-ditional assembly capacityIt can also generate variousobject code formats includ-ing several hex formats tosupport Microchip's propri-etary development tools aswell as third party tools.Also supported are hex (de-fault), decimal and octalsource and listing formats.An assembler users manualis available from MicrochipTechnology distributors fordetailed support. The, diskalso contains a softwaresimulator.

The PIC programmingcourse disk may be ob-tained through the ElektorElectronics Readers Ser-vices under order number946196-1. For price and or-dering information, seepage 70 of this issue.

The files produced by theassembler can be down-loaded to the PIC pro-grammer described inElektor Electronics March1994.

JOINTHE COURSE!

the first half of a programmemory page. It is, there-fore, wise to declare all sub-routines at the start of theprogram. The 'ORG' instruc-tion in line 86 tells the as-sembler to set the internalprogram counter to the indi-


COMPUTERS AND MICROPROCESSORS

Table 6 Control directives

if <expr> Start of a conditional assembly block

else Start of an alternate conditional assembly block

endif Terminate a conditional assembly block

org <label> ... <al:1dr> Set absolute address for following block code

end Terminate assembly code block

Table 7. Macro directives

macro <label> .. [<arg>,[<arg>] ] Begin a macro body definition

endm Terminate macro body definition

local <label>[i<label>] ... Define assembler labels as local to macro

exitm Exit macro

cated address, here, 0000.Immediately after this state-ment, the subroutineWait_ms' starts. The delayintroduced by this subrou-tine is defined in millisec-onds with the aid of a valueread from the W register.

Read instructionsThe first instruction in the`Wait ms' subroutine isMOVWF (Table 8). It tells thecontroller to store the con-tents of the W register di-rectly at location 'ms'. Thislocation was declared earlierin line 65.

The next instructions(lines 100 and 101) cause alocation Called ùs' (for mi-croseconds, ps) to be filledwith the value OFEH. Sincethere is no instruction whichenables that to be done di-rectly, an alternative ap-proach is used in which theW register plays an impor-tant part. The instructionMOVLW (line 100) puts theconstant into the W register.

There are two ways toplace the value '0' into theW register; either useMOVLW 000H, or the sim-pler CLRW instruction. Note,however, that CLRW alsosets the Z flag.

Another instruction toclear the contents of a mem-ory location in the registerfile is 'CLRF'. Like CLRW.CLRF does not make use ofthe W register, and actuatesthe Z flag.

A final option is the MOVFinstruction, which allowsthe contents of a memory lo-cation to be copied into theW register. Alternatively,this instruction enables thememory location included in

the operand, rather than theW register, to act as the 'tar-get'. The result of this in-struction is that thecontents of a location aresimply returned to the samelocation. This seeminglypointless instruction is use-ful with, for instance, I/Oport operations. One in-struction is sufficient to readthe logic state of a port, andreturn the information to thebuffer register. The same in-struction may also be usedto test the contents of a reg-ister for the value '0'.

As already mentioned, thesubroutine waits the num-ber of milliseconds definedvia the W register. This isachieved by using twonested loops. The outer loop(lines 103 through 111)takes exactly 1 ms to com-plete if a clock frequency of4 MHz is used. This loop iscalled as many times as thevalue contained in theW register, via lines 110 and111. The number of itera-tions of the inner loop is notstored as a constant in the'us' register, but added tothe constant of the register.This is done on purpose toallow a correction to bemade to compensate for thetime needed to start the en-tire subroutine. The subrou-tine is finished if locationùs' reaches the value OOH.

ArithmeticinstructionsThe arithmetic instructionsoffered by PIC processors arelimited to ADDWF andSUBWF, and their derivatesINCF and DECF. An applica-tion of the ADDWF instruc-tion may be found in

3

4

5

6

7

8

9

10

2

3

4

6

7

title .Sample flashing LED" ; Program titlesubtitl .Declarations. ; Program subtitlle

Listing Options for MPALClist c=136

list n=60list r=HEX ; [HEX,DEC,OCT]list 1=ON ; [ON / OFF]

list x=ON ; [ON / OFF]

list t=ON ; [ON / OFF]

list e=0 ; [0,1,2,3]

Page

8 ; select controller9 controller equ 56

20

1

2

3

4

5

6

7

8

9

30

1

2

3

4

5

6

7

8 ; Main declarations9

40

1 W

2 F

3

4

5 Input6 Output7

8 ;

if controller == 54 ; PIC

list p=16C54 ;

Adr_Reset equ 01FFH ;

endifif controller == 55 ; PIC

list p=16C55 ;



list p=16C56 ;



list p=16C57 ;


endif

assembler; Columns per line

; Lines per page; HEX as default; Listing ON; Macro expansion on; Truncate listing lines; 0 = Report all Messages; 1 = Report Warnings,; fatals, criticals; 2 = Report fatals, criticals; 3 = Report criticals

; New Page

;54: PIC 16C54, 55: PIC 16C55

16C54

16C55

16C56

16C57

;Destination of Byte -Oriented File Register Operations

equ OOH ; Destination is W Register

equ 01H ; Destination is F Register

; Directions of I/O - Portsequ 01H ; Input

equ 008 ; Output

9 ; Register file declarations

50

1 ; Operational Register File2 INDIRECT equ OOH

3 RTCC equ 01H

4 PC equ 028

5 STATUS equ 03H

6 FSR equ 04H

7

8 ; I/O Registers (Ports)

9 Port_A equ 05H

60 Port_B equ 06H

1 Port _C equ 07H

2

3 ; General Purpose Registers,4 us_Register equ 009H ;

5 ms_Register equ 00AH ;

6

7 ;

8 ; Hardware declarations9

70 LED _B equ 00H

1 LED _P equ Port_A

2 LED off time equ 000H

3 LED_on time equ 0008

4

; Indirect Data addressing; Real Time Clock/Counter Reg.; Program counter; Status Word Register; File Select Register

; PIC 16C55/C57 only

user defined

; LED connected to RAO

; LED off for 256 ms; LED on for 256 ms

5 KEY_B equ 01H ; KEY connected to RA1

6 KEY _P equ Port_A

7

8

9 subtitl "Subroutines"80 page1

2 ;

3 ; Subroutines4 ;

5

6 org 0000H ; Subroutines only in first half

7 ; of page

8

9 ;

90 ; Subroutine Wait_ms1 ;

2 ; Parameter: ms in W Register3 ; Return value: 000H4 ;

5 ; Delay time is 1 ms (W Register) at Fosc 4Mhz

6 ; Note: W Register = 000H <=> 256 ms7 ;

8

9 Wait_ms movwf ms_Register100 movlw OFEH

1 movwf us_Register2

3 W Loop ms movlw OF9H ; 1 loop 249*W_Loop us -F.1 cycles

; StOre ms; correct call time (incl 1 movlw; before calling) for first loop

4 addwf us Register,F ;

5


PIC PROGRAMMING COURSE - 3 116 W_Loop_us nop ; one loop = 4 cycles

7 decfsz ue_Register,F ; us register - 1, skip if zero

8 goto W Loop us

110 decfsz ms Register,F ; ms register - 1, skip if zero

1 goto W Loop Ms ;

2 nop ; correct time of last ms loop

3

4

5 ;

6 ,

7

8

9

120

1 ;

retlw 000H

subtitl "Main program"page

2 ; Main Program3 ,

4 ;

5 Main_Start ; Starting after RESET6 movlw 00EH ; Set RAO, which is connected to7 tris Port _A ; LED, as output8 goto LED_off ; Initially: LED off9

130 Loop btfsc KEY P, KEY_B ; Key pressed? (RA1 = 0?)

1 goto Loop ; No, wait until key pressed2

3 bcf LED_P, LED_B ; LED on4 movlw LED on time ; wait5 call Wait_ms6

7 LED_off bsf LED P, LED_B ; LED off8 movlw LED off time ; wait

9 call Wait_ms140

1 goto Loop

2 ;

3

4 org Adr Reset5 Reset goto Main_Start6 ,

7 end

define reset vectorStart at Main_Start after RST

Fig. 2. Example program for the hardware shown in Fig. 1. The codeshown here may be typed in using any ASCII compatible wordprocessor, and is suitable for the Microchip Technology's MPALC as-sembler found on the PIC programming course disk. Line numbersare added for reference in this article only; they are NOT included inthe LED SMPL.ASM file on the course disk.

Add two 32 -Bit numbers N and Z. Result stored back into N.; If N+Z > 2**32 the CARRY flag is set

N_LL, Z_LL: Bit 0.. 7

N_LH, Z_LH: Bit 8..15

; N_HL, Z_HL: Bit 16..23N_HH, Z_HH: Bit 24..31

ADD LL movf Z_LL, Waddwf N_LL, Fbtfsc 3,0

goto CARRY_LH

Load W with Z_LLADD N_LL and W, store at N LLSkip if Carry = 0

movf Z_LH, W ; Load W with Z_LHADD_LH addwf N_LH, F ; ADD N_LH and W, store at N_LH

btfsc 3,0 ; Skip if Carry = 0

goto CARRY HL

movf Z_HL, WADD_HL addwf N_HL, F

btfsc 3,0goto CARRY HH

Load W with Z_HLADD N_HL and W, store at N_HLSkip if Carry = 0

movf Z_HH, W ; Load W with Z_HHADD_HH addwf N_HH, F ; ADD N_HH and W, store at N_HH

retlw 000H ; Return, load W with 000H

Ripple carry routine

CARRY_LH incfcz Z_LH,

goto ADD LHCARRY HL incfcz Z_HL,

goto ADD_HLCARRY HH incfcz Z_HH,

goto ADD_HHsetcretlw 000H

W

W ;

Load

Load

W with Z

W with Z

LH+1,

HL+1,

skip

skip

if

if

W=0

W=0

W ; Load W with Z HH+1, skip if W=0

overflow => carry = 1

Return, load W with 000H

Fig. 3. PIC assembly code for a program which adds two 32 -bit num-bers.

MOVWF Move W to f

Syntax movwf f Status bits: none

Description Move data from W register to register f

Example movwf ms_Register

MOVLW Move Literal to W

Syntax movlw k Status bits: none

Description The 8 -bit literal k is loaded into W register

Example movlw OFEH

CLRW Clear W register

Syntax clrw Status bits: Z

Description W register is cleared. Zero bit (Z) is set

Example clrw

CLRF Clear f and Clear d

Syntax clrf f,d Status bits: none

Description

Contents of register f are set to 0

d = 0: contents of both data memory location f, and W register areset to 0

d = 1: contents of register f are set to 0

Example clrf ms_Register

MOVF Move f

Syntax movf f, d Status bits: Z

Descriptiond = 0 :

d = 1 :

move contents of register f, result stored in W

move contents of register f, result stored back in f

Example movf Port B, W

ADDWF Add W to I

Syntax addwf f, d Status bits: C. DC. Z

DescriptionAdd contents of the W register to register fd = 0 : result stored in W registerd = 1 : result stored back in register f

Example addwf us Register. F

SUBWF Subtract W from f

Syntax subwf f. d Status bits: C, DC, Z

DescriptionSubtract the W register from register fd = 0 : result stored in W register

d = 1 : result stored back in register f

Note

The subtraction is carried out according to the 2's complement method.The Carry bit is set if the subtraction did not produce an overflow:f > W => C=1.Z=0f = W => C = 1. Z = 1

f < W => C = O. Z = 0

Example subwf us Register, F

INCF increment f

Syntax incf f, d Status bits Z

DescriptionIncrement contents of register fd = 0 : result stored in W registerd = 1 : result stored back in register f

Example incf ms_Register. F

DECF decrement I

Syntax decf f. d Status bits Z

DescriptionDecrement register f

d = 0 : result stored in W registerd = 1 : result stored back in register f

Example decf ms_Register, F


54 COMPUTERS AND MICROPROCESSORS

line 104, where a valueOF9H (copied into W inline 103) is added to the con-tents of location ùs'.

All arithmetic instruc-tions allow either the W reg-ister or the f register in theoperand to function as the`target'. That enables a cer-tain value to be added toseveral T registers in one go.

Unfortunately PIC proces-sors lack instructions of thetype 'add with carry' and`subtract with carry'. Con-sequently, adding numberswhich are wider than 8 bitsrequires the carry flag to beprocessed separately.Figure 3 shows an exampleof a program in which two32 -bit numbers are added.These numbers are 'Z' and'N. 'Z' consists of the bytesZ_HH, Z_HL, Z_LH and Z_LL.The same goes for 'N'.

When using the SUBWFinstruction, it should benoted that this is performedaccording to the `two's com-

plement' method. Conse-quently, the carry flag is ac-tuated inversely.

The use of the DECF andINCF instructions should beself-evident. These instruc-tions decrease or increasethe contents of a memory lo-cation by one, respectively.Here, too, the result isstored into the f registerstated in the operand, orinto the W register. If the re-sult equals 0, the Z flag isactuated.

(940062-3)

Reference:1. Experimentation board forPICs, Elektor ElectronicsJuly/August 1994.

Continued in the November1994 issue.

PIC is a registered trademark ofMicrochip Technology, Inc.

Fig. 4. The PIC-based LED flasher is best built on a PIC experimenta-tion board (Ref. 1).

Microchip announces new PIC16CR57A 8 -bit microcontroller

MICROCHIP'S low-costPIC16CR57A 8 -bit mi-

crocontroller is ideal for I/Ointensive, low -power appli-cations. The new 8 -bit ROM -based microcontcontrolleruses an advanced 0.9 -mi-cron fabrication process toachieve greatly improvedelectrical performance withlower power consumptionand a wider operating volt-age range.

Running at up to 20 MHz,with faster instruction exe-cution than any other 8 -bitRISC microcontroller in itsclass, the PIC16CR57A op-erates from 2.5 to 6.25 Vsources and features apower -down (sleep) modethat further reduces powerconsumption. On -chipmemory facilities include2,048 12 -bit wide words ofmasked ROM for programstorage, and 72 bytes of sta-tic RAM for data. On -chipperipherals include an 8 -bitreal-time clock/counterwith programmable pre -scaler, an oscillator start-uptimer, a watchdog timer

with on -chip RC oscillatorand 20 I/O lines with indi-vidual directional control. Inaddition, the PIC16CR57A issocket and software com-patible with Microchip'sone-time programmablePIC16C57 microcontroller,

and 100% code compatiblewith the 18 -pin 16CR54ROM, providing a simpleupgrade path to existingusers.

Arizona Microchip Tech-nology Ltd., Unit 3, The

Courtyard Meadowbank,Furlong Road, BourneEnd, Bucks SL8 5AJ,England.Tel. (0628) 850303, fax:(0628) 850178.

PIC16CR57A Architecture

ROMProgramMemory

(2048 words x 12 bits)

ProgramBus<12>

Instruction Reg

Program Counter

Stackl

Stack2

Direct Addr <5>

Data Bus <8>

SRAMFile Registers72 Locations

Addr MuxRAM Addr <7>

Addr <7>

FSR

-4,STATUS Reg

MCLR

[ZVI'OSC1OSC2

(a=)

InstructionDecode &

Control

TimingGeneration

OscillatorStart-up Timer

Power onReset

WatchdogTimer

gM u x

W Reg

Clock/Counter

RTCC

I/O Ports

PortsA, B, C

940062-111-12



A

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56

TV LINE MONITORMeasurements on TV signals are notoriously difficult. Even if you have an

oscilloscope with a trigger button marked 'TV' it is practically impossible to select aparticular line from the picture signal. That problem is solved once and for all by theTV line monitor described in this article, because it allows any line in the composite

video signal to be selected in a simple manner.

FOR a well-founded verdict on theoperation of a TV set it is often re-

quired to perform measurements onindividual lines in the video signal asprocessed by the set. For this purpose,a number of special test signals (inser-tion test signals, ITSs) are included innearly every TV broadcast, whether bysatellite or terrestrial. These signalsare contained in picture lines which

Design by J. Matus

are normally invisible to the viewer,i.e, they fall outside the actuallyviewed raster. The TV technician, how-ever, views them on an oscilloscope.The basic functions offered by the ITSswill be discussed further on.

The picture line monitor is a handyand multi -functional tool for repairingand adjusting TV sets and other videoequipment, such as video recorders

41'

(VCRs). The TV line monitor is basedon a PIC16C54, a type of microcon-troller which has been used on severaloccasions at the heart of different cir-cuits described in Elektor Electronics.The PIC comes ready -programmedthrough our Readers Services, and re-duces the IC count in the circuit tothree (well, actually four if you includethe voltage regulator). The line monitorenables an oscilloscope to be triggeredat the start of the TV line selected byyou, the user. The TV line you wish toview on the scope is selected with theaid of two press -keys, and is indicatedon a readout consisting of three 7 -seg-ment LED displays.

The circuit diagram of the TV lineselector is given in Fig. 1. Broadlyspeaking, the circuit consists of twoparts: a synchronisation separator anda processor (with LED readout) whichacts as a general control. The compos-ite video signal (CVBS) is applied to thecircuit via socket K1. To keep the loop -through connection to the oscilloscopeas simple as possible, the CVBS signalre -appears on K2. A simple RC filter,R17 -C2, removes spurious pulses andother noise from the video signal. The`clean' signal reaches the CVBS inputof ICI, an LM1881, via coupling capac-itor C3. The LM1881 from NationalSemiconductor is designed specially tounravel composite video signals. Thefour outputs of this IC supply (1) thecomposite synchronisation signal, (2)the vertical synchronisation pulses, (3)a colour burst marker and (4) anodd/even field marker. These signalsprovide all the information necessaryto determine the timing of a compositevideo signal. The TV line monitor onlyuses the composite and the verticalsynchronisation signals. The positionof the colour burst is of no conse-quence to the circuit. Likewise, theodd/even field signal is less suitablefor use here, mainly because it tendsto be erratic if the video signal con-tains noise. This was considered animportant drawback for a test instru-ment.


TV LINE MONITOR El

VIDEO

CK1

VIDEO

CK2

5V

0IITCT11

IC3

PIC16C54

RBO

RB1R1

16

RB2

RB3

RB410

RB511

OSC1C1 RB6

12

RB713

I18p 15 OSC2/CLKOUT

RAO17

3

RA118RTCC

RA2

RA3

5V

R2

00

R3

00

R7=1220o1-7,

122052220S2

1 220S21--

LD1HD1107 6

10

22051-7I 2201-

R13

R14

a

f 09 CC CC

dp

2k2

3

T1

8

LD2HD1107 6

10

9

7

5

4

2

BC547BR15

a

b

d

O 09 CC CC

73

S2

DOWN UP

R4

R5

2k2

dp

T2

LD3HD1107 16

10

9

7

5

4

2

BC547BR16

f LJr7 09 CC CC

ECM

3

R17

68052

5V

C3

OR18

2

IC1

100n

6

C2 C4

CVBS

RESET

V SYNC

C SYNC

0/E

BURST

R6-- 5V R20 C5

0 ECM4n7

15 14

RCX CX

70p 1100n

K4

R19LM1881

IC4

C7

7805

2

IC2a

13

5V R21 C6

0 ECM1n

7 6

9

5V

10

c)1141 -7N

5V

IC2 = 74HCT221

RCX CX

111

R IC2b

101'425V

C8MIM IC1TOOn O

C9-100n

cioIC2 Imo

100nO

a) C11

5V

0IC3 mlm

100n

12

T3

8

BC547B

TRIG

R22

1717071--)K3

940065 - 11

Fig. 1. Circuit diagram of the TV line monitor. The PIC processor, IC3, is supplied ready -programmed.

The composite sync signal is appliedto monostable multivibrator IC2a,whose monotime equals about threequarters of a picture line. This time isused to suppress the half-line pulseswhich occur during the field flybackperiod. The output of the monostablesupplies a clean horizontal sync sig-nal, which can be used straight awayby the processor.

The timing diagram in Fig. 2 showshow the odd/even field changeover isusually marked in the signal. Duringthe field flyback period, a number ofextra sync pulses are inserted into the

horizontal synchronisation signal,half -way the line period.

Since it is essential for the TV linemonitor to detect the field changeover,the processor has to restore the rele-vant signal from the vertical and hori-zontal synchronisation pulses(remember, the odd/even field signalsupplied by the LM1881 is not used).Figure 2 also indicates a delay of half aline period in the vertical synchronisa-tion signal. This time has to be com-pensated to make sure that the triggerpulse for the oscilloscope is properlytimed.

MAIN SPECIFICATIONS

Video standard:Line number display:

Processor:Controls:Field:Picture line:Output:Detection:

PAL3 x 7 -segment

LED

PIC16C54two press -keys

selectable, odd or evenselectable, 1 through 625

digital trigger pulseno or bad input signal


58 TEST AND MEASUREMENT

IC1/1

IC2/13

IC1/3

IC1/7

IC1/1

IC2/13

IC1/3

IC1/7

2nd field 1st field

I 621 I 622 I 623 I 624 I 625 1 1 2 1 3 1 4 1 5 1 6

-H = 1st field

I 7 1

1st field 2nd field

I 309 I 310 1 311 I 312 I 313 I 314 I 315 I 316 I 317 I 318 I 319

L 2nd field

940065-12

Fig. 2. The change from an odd -numbered to an even -numbered field in an interlaced TV pic-ture is marked by extra horizontal synchronisation pulses which are inserted at about half-way the line period. These pulses appear around the vertical sync pulse.

The processor: heart of thecircuitAs already mentioned, a PIC processoris used for all computing and controlfunctions in the circuit. These func-tions are:

- driving the display in multiplexmode:

- scanning the press -keys for activity;- counting the picture lines;- enabling the trigger pulse.

All functions are carried out by aclever piece of software and the PIC'son -board 8 -bit timer. A problem withthe PIC processor used is that it cannot handle interrupts. Consequently,the software must use 'polling', i.e.,very frequent checking whether the de-sired picture line is already present atthe input. Polling is an acceptable al-ternative if interrupts are not avail-able, but it does take time. Asillustrated in Fig. 3, it can lead to alarge timing error. Obviously, thefastest processor response is obtainedif the desired counter state is reachedat point 'A'. If the state is reached atpoint `B', a considerable delay is intro-duced because the comparator has towait for the next polling cycle. This

delay would cause an amount of jitterin the trigger pulse that can not be tol-erated in a test instrument. Hence, atrick had to be devised to prevent grosstiming errors. The solution is simple aswell as ingenious: instead of generat-ing a trigger pulse, the processor only

Fig. 3. Polling may cause large variations inthe time needed by the processor to respondto a counter state match. This flow diagramshows how the delay is introduced.

enables a monostable (IC2b) whichdoes so. The monostable is startedwithout any delay by the horizontalsynchronisation pulse. The timing isillustrated in Fig. 4. The 'only' task ofthe software is to enable the mono -stable in time. That does, however,create some exacting demands on thespeed of the processor, and the com-pactness of the program executed.Provided it is well written, the softwareshould work reliably despite fairlylarge variations of the clock frequency.The present circuit works well at clockfrequencies between 3 MHz and5 MHz, allowing the inexpensive RCoscillator variant of the PIC processor

Video

IC2/4

IC3/17

IC2/5 trigger pulse

940065 - 14

Fig. 4. After the monostable has been enabled, the horizontal sync pulse causes the scopetrigger pulse to be generated.


TV LINE MONITOR 59

to be used without reducing the re-peatability of the circuit.

Ease of useThe TV line monitor is controlled withthe aid of two press -keys marked '+'(up) and (down). The picture linenumber selected in this way appearson a bright LED display. Any time akey is pressed, the line number is in-creased (+) or decreased (-) by one. Ifyou keep a key pressed, the line num-ber will step up or down automaticallyat a rate of two per second. If you keepthe key pressed longer than 2.5 s, theauto -step speed goes up to 25 lines persecond. The other field is selected bypressing both keys at the same time. Ifa suitable video signal is not present atthe input, the circuit shows a movingbar which travels round the outer dis-play segments.

Finally, note that the circuit is onlycapable of recognising both fields in apicture if the input signal meets thePAL standard as regards interlacing.

Action!Having dealt with the design back-ground of the circuit, it is time to dis-cuss more practical things, i.e., theconstruction and use of the TV linemonitor.

The artwork of the single -sidedprinted circuit board designed for theinstrument is shown in Fig. 5. All com-ponents, including the three displays,the three 'RCA' sockets and the twokeys, are accommodated on the board.

Start the construction by fitting thefive wire links. Next, fit all passivecomponents at the proper locations(refer to the component overlay on theboard and as shown in Fig. 5). Finally,mount the active parts, the socketsand the PCB terminal block. That com-pletes the construction. Since thereare no adjustment points, the circuit isthen ready for use.

Connect the circuit to a mainsadapter capable of supplying an out-put voltage of about 8 V d.c. at a cur-rent of at least 100 mA. Connect acomposite video signal (PAL standard)to socket K1. Connect the input of theoscilloscope to K2. Next, connect K3 tothe external trigger input of the oscillo-scope. Select external triggering on thescope, and set it for a sensitivity of0.5 V/div., d.c. coupled.

Switch on the line monitor, andcheck that the LED display reads '1'.The contents of the same line shouldbe visible on the oscilloscope screen.Depending on the timebase setting,successive lines may also appear onthe screen. If an unsuitable video sig-nal is applied to the circuit, the outersegments of display LD1 will go on and

INSERTION TEST SIGNALS

Although the vast majority of TV viewers will never notice, nearly everyTV picture contains a large number of special measurement signalstransmitted in two pairs of successive lines, 17-18 and 330-331. Thestructure and function of these insertion test signals (ITSs) is usuallybased on CCIR recommendation 473-3.

U

(VI +Line 17 Line 18

IC (b) (C) (d) (*)1,0. - -'

0.5 1.5 3.0 443...4.8-5.80.65----------1

'MMM

_,Hz Hz HzMMHz Hz

MHz

0.440.3- i

BurstLine sync

.--Multiburst17

Pb/w

2T 20T BursLine sync 18

-

0 12 22 2630 34 40 44 48 52 56 6264 76 84 88 94 100 106 112 118 124 128.__,(us)

900079.11*

Picture lines 17 and 18 may be used by the TV technician to test a largenumber of receiver functions. The black/white bar (a) is a reference toestablish the maximum black and white levels. The 2T pulse (b) is testsignal with sine -shaped edges and a total duration of 0.2 his. It is used todetermine the picture resolution. An attenuation of 20% is still tolerable.The 20T pulse (c) is used to test the response of amplifiers to luminanceand chrominance signals. The next test signal is a monochromestaircase consisting of 140 -mV steps. Finally, test signal (e) contains asequence of fixed frequency bursts ranging from 500 kHz to 5.8 MHz.This 'multi -burst' signal serves to ascertain the frequency -dependentbehaviour of the video amplifiers.Picture line 22 is usually empty, i.e., it contains no video information. Ithas a function, though, enabling the total noise contribution of thereceiver to be checked.

u(V) T

Line 330(1) M

Line 331(91) (g2)

1.0-

--rzA - v

%/r v

0.65-

0.44-

f.. ..44

74, .44:7

4i A0.3 . - _/ A

4 -4 -

0--,,

Burs 2T Staircase withLine sync 330 colour subcarrier

-.Burst ExtendedLine sync 331 colour burst

' ' I

0 12 22 26 30 40 44 48 52 56 60 64 76 78 82 86 92 98 124 12862 (Ps) -II.

900079 11*

Picture lines 330 and 331 may be used for two basic measurements. Line330 contains the same 'max. black/white' and 2T pulses as line 17. Nextcomes the colour burst staircase (f) from which the colour separationcircuit in the TV set should deduce a clean 30-ps pulse. The last testsignals are (g1) and (g2) in picture line 331. These enable interferencebetween chrominance and luminance signals to be traced.


60 TEST AND MEASUREMENT

Fig. 5. Component mounting plan and track layout of the PCB designed for the circuit.

off describing a circle. If a correct sig-nal is applied, however, and the circuitis fully functional, any line numbercan be selected very quickly by press-ing the '+' and '-' keys and watchingthe LED display. (940065)

For further reading:Colour television, by Geoffrey Hutson,Peter Shepherd and James Brice.McGraw-Hill Book Company. ISBN 0-07-084199-3.

0 1 A ' Resistors:R1 = 41(07R2;R3 = 100k0R4;R5;R6;R14;R15;R16 = 2k02R7 -R13 = 2200R17 = 6800R18 = 390k0R20;R21 = 15k0R22, 1000

Capacitors:Cl = 18pFC2 = 470pFC3;C4;C8-C11 = 100nFC5 = 4nF7C6= inFC7 = 100uF 25V

Semiconductors:T1;T2;T3 = BC5478IC1 = LM1881 (National

Semiconductor)IC2 = 74HCT221IC3 = P1C16C54 (programmed; see

below)1C4 = 7805LD1,LD2,LD3 = HD11070 (orange)

Miscellaneous:K1;K2;K3 = PCB mount line socket.K4 = 2 -way PCB terminal block, raster

5mm.S1;S2 = Digitast presskey w, 12mm

cap.Printed circuit board plus programmedPIC (IC3); set order code 940065 (page70). The PIC is also available sepa-rately as order code 946643-1 (page70).

Fig. 6. Completed prototype. Note the compactness of the circuit.



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THE OFFER OF 1994 IComputerControlled

Laser VideoOne of the most amazing surplus deals Disk Playerthat we ever been able to offer you!The Philips VP410 LaserVision player, in as new condition, unit fea-tures full computer control, Plays standard 12" LaserVision disks withstartling visual and audio quality in two channel stereo or mono.When controlled by a computer, it may also be used as a versatilehigh quality storage / retrieval medium. It will play back eitherLaserVision CAV (active play) or CLV (Long Play) discs (which cov-ers most types of commercially available video discs). Some of themany features of this incredible machine are:RS -232 INTERFACE RGB / COMPOSITE VIDEO OUTPUTBNC+SCART INTERFACE PAL! RGB DECODERIR+WIRED REMOTE CONTROL FAST RANDOM ACCESS

SPECtRu PURCHRSE only E399.00(F)

BBC Model B APM Board£100 CASH FOR THE MOSTNOVEL DEMONSTRABLE

APPLICATIONBBC Model B type computer on a board. A major purchase allows usto offer you the PROFESSIONAL version of the BBC computer at aparts only price. Used as a front end graphics system on large net-worked systems the architecture of the BBC board has so many sim-ilarities to the regular BBC model B that we are sure that with a bit ofexperimentation and ingenuity many useful applications will be foundfor this board!! It is supplied complete with a connector panel whichbrings all the I/O's to 'D' and BNC type connectors - all you have todo is provide +5 and +12 v DC. The APM consists of a single PCBwith most major ic's socketed. The ic's are too numerous to list butinclude a 6502 / 6512 CPU, RAM and en SAA5050 teletext chip.Three 27128 EPROMS contain the custom operating system onwhich we have no data, On application of DC power the systemboots and provides diagnostic information to the video output, Onboard DIP switches and jumpers select the

9EPROM sockets for user software. Appx. Only £29.5ECONET address and enable the four extra

dims: main board 13" x 10". I/O board 14" x for £53 (B)3". Supplied tested with circuit diagram, Gdata and competition entry form.

19" RACK CABINETSSuperb quality 6 foot 40U

Virtually New, Ultra SmartLess than Half Price!

Top quality 19" rack cabinets made in UK byOptima Enclosures Ltd. Units feature design-er, smoked acrylic lockable front door, fullheight lockable half louvered back door andremovable side panels. Fully adjustable inter-nal fixing struts, ready punched for any config-uration of equipment mounting plus readymounted integral 12 way 13 amp socketswitched mains distribution strip make theseracks some of the most versatile we have

ever sold. Racks may be stacked side by side and therefore requireonly two side panels to stand singly or in baysOverall dimensions are: 77-1/2" H x 32.1/2" D x 22" W. Order as:

Rack 1 Complete with removable side panels. £295.00 (G)Rack 2 Rack, Less side panels £175.00 (G)

Over 1000 racks in all sizes from stock !Call with your requirements.

LOW COST RAM UPGRADESINTEL 'ABOVE' Memory Expansion Board. Full length PC -XT andPC -AT compatible card with 2 Mbytes of memory on board. Card isfully selectable for Expanded or Extended (286 processor andabove) memory. Full data and driver disk supplied. In good usedcondition fully tested and guaranteed.Windows compatible. Order as: ABOVE CARD £59.95(A0)Half length 8 bit memory upgrade cards for PC AT XT expandsmemory either 256k or 512k in 64k steps. May also be used to fillin RAM above 640k DOS limit. Complete with data.Order as: XT RAM UG. 256k

512k1 MEG x 9 SIMM 9 chip 12Ons only

£38.95(Al£29.95(At

No Break Uninterruptible PSU'sBrand new and boxed 230 volts 1 KVa unintetruptible power supplyfrom system from Densei. Model MUD 1085-AHBH. Complete withsealed lead acid batteries in matching case. Approx time from inter-rupt is 15 minutes. Complete with full manual.

0 .1611J(G)Order as: MUD 1EMERSON ACCUCARD UPS, brand new 8 Bit half length PC com-patible card for all IBM XT/AT compatibles. Card provides DC powerto all internal system components in the event of power supply fail-ure, The Accusaver software provided uses only 6k of base RAMand automatically copies all system, expanded and video memory tothe hard disk in the event of loss of power. When power is returnedthe machine is returned to the exact status when the power failed !The unit features full self diagnostics on boot and is supplied with lullfitting instructions and manual. Normal price £189.00

Only £99.00(6) or 2 for £195(c)

Issue 12 of Disp fay News now available - send large SAE - PACKED with bargains!0004

0440

040

SOO

400 040 044 440

-ELECTRONICS-

LONDON SHOPOpen Mon -Sat 9:00-5:30

215 Whitehorse LaneSouth NorwoodLONDON SE25

DISTEL © The OriginalFREE On line DatabaseInfo on 1000's of items

V21,V22, V22 BIS081 679 1888

ALL MAIL & OFFICESOpen Mon -Fri 9.00-5:30Dept EK. 32 Biggin Way

Upper NorwoodLONDON SE19 3XF

ALL V ENQUIRIES

081 679 4414FAX 081 679 1927

All prices for UK Mainland. UK customers add 17.5% VAT to TOTAL order amount. Minimum order 210. Bona Fide account orders accepted from Government,

j Schools, Universities and Local Authorities - minimum account order £50. Carriage charges (A)=03, (A1)=04.00, (B)=£5.50, (C)=08.50, (D)=012.00, (E).£15.00,ESTABLISHED (9.£18.00, (G)=CALL. Allow eel:wok 6 days for shipping - faster CALL. Scotland surcharge CALL. All goods supplied to our Standard Conditions of Sale and

25 YEARS unless stated guaranteed for 90 days. All guarantees on a return to base basis. All rights reserved to change prices / specificationswithout prior notice. Orderssubject to stock. Discounts for volume. Top CASH prices paid for surplus goods. All trademarks etc acknowledged. B Display Electronics 1994. E & 0 E.



WE HAVE THE WIDEST CHOICE OF USEDOSCILLOSCOPES IN THE COUNTRY

H.P. 3456A DVM 64,a15t DC/True RMS AC/Res. HRIB MOEIP/DANA341D MIcrowave Frequency Counter 20Hz 1/i1.11, ERNIH.P. 5341A Frequency Counter 50MHz - 1.5GHz LED ..... 1.300MARCONI 3435 Dlgital Freq. Meter 20,1z ..................... L400RACAL 1998 Frequency Counter 1.3GH, OptIons GPIS & Iligh in ,..., £000RACAL 1991 Universal Counter/iimer 180MHz 9 diet .. L150MARCONI 2437 Universal Counter DC. 100M14,14,11gil L175MARCONI 24314 Frequency Counter 10Hz200MHz H digit L150MARCONI 2430A Frequency Counter 10Hz.80MHz 8 dig!. L125RACAL 9918 Frequency Counter L200RACAL 9913 Frequency Mete, 10Hz.80MHz 8 digit ........ L125RACAL 9911 Frequency Meter 10Hz120MHz 7 digit.... £100RACAL9911 Universal Counternmer DC-200MHz acme 11150

RACAL9904 Universal Counter/Timer DC-50MHz 701gE 1175RACAL9901 Universe, Counter/Tlmer 00.50MHz 6 dIglt L100DATRON 10610 - 6.5 aiglt Autocal MultImeter true RMSM.R.rinen I £580H.P.3490A 5 Digit Mult.meter AC/DC/Ohms L20000.0.34350 3-/, Dilt Multimeter AC/DC/Ohms/Current I I II L100PHILLIPSPM2534 MultlFunct.n WM 3./u.5./, Az GI.III/IIII L450SOLARTRON 7150 8.636 clIgit DMM w1t5 IEEE £400SOLARTRON 7045 4.5 digt Mu ltimeter Volts, Alrips/IIInie., £130

WAYNE KERR 5905 Automate Precision Brn10.111511 1900MARCONI TF 2700 Universal Bnclge Battey 01/..i.dwil from L150MARCONI iF 1313A Unwasal LCR Bridge 0.01 L125WAYNE KERR B424 Olgtal LCR Meter ...... E200HEATHKIT .8 ELC Bridge £50BRADLEY 192 Oscilloscope Calibreter ........WILTRON 500 Scaler Network Analyser witell.......1.4.. 00

aeH.P. 5005A Signat Analyser ERSO

FARREL H30/1000 -30y, 0.100Amps Meten41FARNELLTVS70M1,2 70volts 5Arnos/39.110, II/ amp.. Minenel ....... £200PARNELL B30/10 30Volts 10Arnos variableFARNELLL30E 0.30Vo,, 0-0.5Amos Metes. 1425MARCONI(WEIRFF2154 0.30V 10; 0.150 :A r ...Yee Melnrell L50M.P. 651600.300: 0.6MA metered .......... £150BRANDENBURG Male. 4728 PSU 0/ 12000.. L200FEEDBACKFG600 0.01Hz- 100HHz Sme/Se. II. £00LYONS PG71N Pulse Gen. PRF 1H5.20Mli1 lower .. L75FARRELL PG101 Pu Ise Ger. 100nSece 10MI lulu,. 11181 1125LONDON LA1 M025 Autho Analyser .... L500UNAOHM EP501 Audio Analyser ..... .......... L350PHILLIPS P65518 Colov TV Pattern Generale/ E1250RADFORD LD04 Low DISTORTION OcIllator £300RADFORD LDMS2 Low DISTORTION Mee., 4 ,q,1 L300

TEKTRONIX 7000 SERIES OSCILLOSCOPESAVAILABLE FROM £200 . PLUG .INS SOLD SEPERATELY

TEKTRONIX 2465 4 05, 300 MHz Delay Cursors . L1700TEKTRONIX 2235 Dual Trace 100 MHz Delay Sweep L700PHILLIPS 3065 201 Channels 100600 Dual TB Delay Sweep L800T KTRONIX 485 Dual Trace 350 MHz Delay Sweep ..... L750TEKTRONIX 475 Dual Trace 200 MHz Delay Sweep...... O

T KTRONIX 4658 Dual Trace 100 MHz Delay Sweep... LM500

TEKTRONIX 465 Dual Trace 100 MHz Delay Sweep...... £400T KTRONIX SC504 Dual Trace 80MHz in 0650313 as new L500TEKTRONIX 2215 Dual Trace 60 MHz Delay ' wwwp 0450T KTRONIX 455 Dual Trace 50 MHz De,ay Swims L400

ITACHI V650F Dual Trace 60MHz Delay Sens! E350HILLIPSPM3217 Dual Trace 50MHZ Delay ...ewe L400

LEADER LB0.520A Dual Trace 35Mlz ......... L226OULDOS1100 Dual Trace 30MHz ............ L100

IWATSU 555702 Dual TraCe 20000 ....... L300DUD OS250E1 Dual Trace 15MHz. 0335

THANDER T0315 Dual Trace 20Mhz Ma,ns/Battery £300.P. 1741A Dual Trace 100MHz Delay Sweep Analogue Storage .............[350

THIS IS JUST A SAMPLE . MANY OTHERS AVAILABLE

HEWLETT PACKARD 1740A100MHz Dual Trace, Delay Swoop

For Only £3 50MARCONI2018 Synthesized AM/FM Sig Gen 801(Hz-520011e ...... L700H.P.86409 Signal Generator 20H5-1024MHz ............... .... E1000H.P.8620C Sweep Ocillator with 882450 69 - 12.40Hz L400

SYSTRON DONNER 1702 Synth. AM/FM Si Gen 100110 I1.11/ £000RACAL 9081 Syntheslzed AM/FM S.g Gen 5 - 520MH5 .. (500FARRELL 550520 Synthesized AM/FM Sig Gen 10-320M110 £400MARCONI 2361 Sweep Generator System 251(Hz .1CCOMIli £300MARCONITF2008 AM/FM SIg Gen 10101z - 510MHz SNP/411.11111v 8200MARCONITF2015 AM/FM Sig Gen 101,01z - 510MHz .. L200MARCONI TF2015 WIth Synchronizer TF2171 (lock 0051 £350PHILLIPS P515326 AM/ FM Sig Gen 100101,110MHE £300MARCONI TF20028 AM/FM Sig Gen 100Hz - 88MH, M(411445 ........E150MAR/SANDERS 6600A Mw. Sweep Osl wt, 6551 PI14m .00,1,10110' 1GH1 4300

H.P.8690B Microwave Sweep Osc wcM1 .38597A Plug.in 21.1.10118 .1111i115... £300

H.R. SMITH ANTENNA type 126024......... L2000MARCONI6500 Automatic Armmtutle Analyem E1500H.P. 436A Power Meter , ............RACAL INSTRUMENT

RECORDERECR

lyne Mem .11110Lill°

H.P. 3575A Gain Phase Mete, 1, - 13MHE. L400H.P.3312A Fctn. Gen. 0.1Hz-13MHz AM/FM ..mme Ine../......lii 1 m L400MARCONITE2337 Automatn Distormon Meter .............. L200SAYROSA Automate Modulatior Meter Doe 252B ....... £125

TEKTRONIXCP5250 Trtple Output PSU 202050.5AVen swim £225EKTRONIXCF9250 Gen. 0Hz-2MHzSIne/So/Ti,h. £335

TEKTRONIXGDM250 OigitalMulklimeter 37,41 LED .. gm

NEW EQUIPMENTMAME° OSCILLOSCOPE HM 1005 Tnple Trace 100MHZ.Delay TImeuase 1847HAMM OSCILLOSCOPE 1101,04 Dull 'Row honti/

Delay 90000MAME° OSCILLOSCOPE 151.011.7 Dull Trw ...MIMI/Component Tester .. .................HARES OSCILLOSCOPE 11511.11...3 Dual Tra. .....1L111/

Digital Stage ES53All other rnotlels ava,laule - all osodloscopes supplied wito 2 probes

BRUEL & KJOER Vibration System(Large) P -0.A - OTHER B&K EQUIPMENT AVAILABLE

BLACK STAR EQUIPMENT (p&p all units LE)APOLLO 10 - 100MHZ Counter Tlrner Rave/ Perio0/TiMe interval etc

. 1222APOLLO 100. 100MHZ ,As above with man. him Ilmile IanMETEOR 100 FREQUENCY COUNTER 100M11/ £119METEOR 600 FREQUENCY COUNTER 500M11/ £145METEOR 1000 FREQUENCY COUNTER 1GH/ L1130

1UPITOR 500 FUNCTION GENERATOR 0.1 5161,001411/ !,1s,/,11,. 11 1119ORION COLOUR BAR GENERATOR Pa /TV/VIPea .......... ... L229

All other Bieck Star Equament svm1511..

=21712=EMH.P. 85654 0.01 - 22GH,H.P. 853 wth 8559A 0.01- 21GH, ......... .. L4500

'

............. -A5IRITSU M4 Tracking Generator 111M11111 I 015 Met, ... L1500

£1000

POLARAD541.1 10MH518GH5 ............. ... L1500ANDOAC8281 wan AG8211 1700Mnx ..... ,H.P.182,111 8558 10010,1500MHz ..

£1500am

H.P. 141T wIth 8554B & 8552B. 500KHz.1250MIt . .. L1200H.P. 141T wItM1 B5538 & 8550A 1NH, 110MHx ........MARCONITF2370. 301.w. flown L1000H.P. E1444 & 8443 Tracking Genaratom. II 01 from ..... L300H.P. 141T Main Remo. only. Good Tame ................

OSCILLOSCOPE PROBES SwItchable xl, 010 (PIP E31 112-

Used Equipment Guarantee . Manuals supplied If possibleThis is a VERY SMALL SAMPLE OF STOCK. SAE or Telephone for II ts. Please check availability before ordering CARRIAGE all units £16

VAT to be added to Total of Goods and Carriage

STEWART OF READINGMUM110 WYKEHAM ROAD, READING, BERKS RG6 IPL Fni

Telephone: (0734) 288041 Fax (0734) 351698 Callers Welcome 9am5.30pm Mon -Fri (until 8pm Thurs)

Inventor toroidal transformers 225VA.10.3910.5 primary 0-223205 80,01111

LED'a 3mm or 6nm roc or greenyellowHigh Intensly red Teen or yelmw III

cadre ties top each £5.95 per '0001'1'

High quality photo resist maw ciadDimensions Single Sided

3x4 mches £1.39

400 inches 52756x12 irches 06.20

1202 inches 5.12.25

Rechargeable batteriesAA 097) 500 mA1-1

AA 700mAF

C 2AH with solder tags

C, 4Ahlwith mcer lags1 200 wit soidar tags .AAA (6016) 180mAHAA 50OrrAH win 001dr:01..1.

0+17'111 '.BAHDO8?21 1 2AP

PP3 9.4V 110mAH

Sub C with &doer

13 AA with tags (italics CTVIStandard Charger charges 4 AA 1,i on!, 2 0. 11 405 re Os

le 1214 hours +1X003(12.3 Or .1 id 111111.0111.0 at a

Me. ... 05.95

High power charger as above but charges lei... ad Ds in 5AAs Cs and Ds must be charged ia £1095

Nickle Metal Hyclryde AA cells h gh amaia' will, le memory

1000nVi . £3.85 12CCmAH 014.40

Special offers please check for availability422151-rm dia '2v 01,45

dick 31 4.171mmx16mm dia tvith rec & black ream 4.8v...55.95Computer grade capacitors w In screw termirals

682000 152 52.95 13)00;116, £'505E0080600 .£4.95

7 segment commcr arms ;ec dismay 124,. £0.45

Lt12331AT5.0 i0 A Drop Gut 5O Moe T0220 packace £0.85

and7912 122 lA raga atu's rH i0 per 100

LC.',37K TO3 case mrable regJI 111 1' PI 11.44 '00+GaAs FET low 'aakage current She :1 I '2.95 each

89.95 10+ . . 95 "00-ES25C U Charnel

130559 transistor .....74tS05 hex inventor

useo 8745 Micaacontrolr-SL952 UHF I, p1'6'

vat data ohs,:0027502 ..... 1' 25 intl. 90p 100 +C24007U0 10p 100+. 6p 1300+

Sinclair light qr. 11111.1:1.1 r': log cod PP3 dip gives asignal when pointed al 50hz 1,900059 light with output wave

ion dean . 03.95

00.2C convertor Reliability model `212F5 12v in 5v 20ernaout 300M inpui. to °Maul isolation with nate £4.95 each cr pack

E39.50

Hour counter used 7 dig.: ,s, Hz . ......01.45

Iry 02995aoeach

11p each

30p eatdl Iv'' 1111111

epoxy glass boarOS

Double Sided

£1.23

£299

00.99

. £1.75

. 89.60

54.95

. £1.75

£1.55

.. 02.20£2.60

.24.95

£230.£1.95

03.45

aer ICC

'1110 per IOC

£3.50

11 ,1st, 1111.11.111,1.1g package

OWERTY keyboard 58 keys good duality switches new E5.00

Ai rpax 08.29)3-C Iar,s stepping moor 14.77.5 step 270,68mm de body 6.3150 shaft . £895CO . 020020 'or a box of 30Polyester capacitors Pox type 22.5mrn lead pitchC.9yr 2502dc 18p each. 14p 100- 9p 1000+lul 250Vec 20p emu. 15p 130+. 10p 1000+2241 250Voc (27.5mm pitchl 30p each. 20p 100+, 751,1000-3.30f

100Vdc 30p each 20o '00+ , 151 1000+luf 500 dpclar a ectroltic axial leads '5p each 7.5p 1000-).2281250v poNester axial .ears . ...15p each. 7.5p 10C+

Pclypropylene ' of 40017dc (Mime MKPle) 27.5mm pitcn32x29x17mm case..._75p each. 60p100+Phillips 123 series solid aluminium axis. ieacs

33 of & 2.2uf 401....... 40p each. 25p 100+Phillips 108 series 220 658 anal 30 each 15 p 1000+Mutiayer AVX ceramic capacitors al 5mm pitch 100v000p'. 150pf. 22Cpf 13.0000110m 'Op earn. 5p 100+.3.5p 1000+. 500pf compression limns' 60p40ut 370Vac motor mart capacito- 'dialectol type containing50 DCDSI 55.950 £49.50 for 10I,Velwyn W23 997 '20 ohm 353 each, 20p IOC+

68Cohrn 211/ metal first resist- 40 100+. 2p 10004

solid carter. 'misters very low inci4canre ideal for RF circuits?701.m 2W. 6echm 2W 25p each. 15p each 100+ we lave a

range of 0.250 3 5010 anc Ow colic carbon resistors pleasesend SAE 'or 1stP.C. 400w PSU Mei oari 201035-001),mM standardmote -tom and 5 disk dim connectos. fan and mains inoutlet ad -motors on bat< and switch on the side (top 'or

tower case' dims 212x'497."49mm exclding switch .. £20.00each..._E13e.00 for 6MX180 Digital Multimstin ' !les 1033v4e 750 vac

20or 200n9 trans sty. HI, '.5/ battery test £12.95MA027256-3 Eprgens . ..... 52.00 each, 125 100+

P swrch 3900 12 pin I .49 60p each.

4Cp IOC+

ve DOMS f0' 5.25 risk dm, v in foe a pans

supply hem grey plasio 67026804.'1.e 07.95

£49.50 for IC

HarChell ultrasonic -emote cent-cl E3.95

01/2466 gas relay 06x1Cmrr dia wit 3 4.1rE. P.1115.111. will o'SC

WorA as a r.500 lent 2)p each ar 07.50 per III

A23 '2': battery kr aiarms cr lighters '5p eat. £50.00961100

Al ereducts. aeverised are nets and unused unlessMews@ staled Vide ,ar:ge 91 CMOS TTL T4r1C 74F

Linear T-ansistors Kits recnargeable beteriascapacitors 133.5 etc alrays n stock

,,ease ado 01.95 in,ards P&PVAT lariats pr:c_0

JPG ELECTRONICSDEPT EL, 276-274 Chatsworth Road,

Chesterfield S40 2BH

AccessiVisa Orders

(0246) 211202

Callers Welcome

QUANTEK FC2000ULTRA HIGH SENSITIVITY

FREQUENCY COUNTER/FINDER* 1MHz - 2.4GHz

* Sensitivity less than 1mVfrom 10MHz to 800MHz

* 2 Gate/measurement periods

* Display hold switch

* Bright 8 digit LED display

* Charge & Gate LEDs

* Aluminium case -100 x 87 x 28mm

* 700mAh Ni-cad batteries

* Maximised sensitivity formeasuring transmitted

radio signals at a distance

* Supplied with mains adaptor/charger & telescopic antenna

.£119+ P&P

MADE IN UK12 Months Guarantee

TO ORDER CALL

021 457 7994FAX ORDERS 021 457 9745

QUANTEK ELECTRONICS,1678 BRISTOL ROAD SOUTH, BIRMINGHAM B45 9TZ

Access

looking forICs TRANSISTORs SEMIs ?especially those hard to find ?

Why not give us a buzz?WE STOCK A MASSIVE RANGE

We specialise in devices with the following prefix(to name but a few):2N 2SA 2SB 2SC 2SD 2SJ 2SK AN BA BC BD BDT BFBFR BFY BFX BU BUK BUT BUV BUW BUZ CA DTAHA IRF LA LB LC LF LM M MC MJ MJE MM MPSMPSA MPSU NE RC SAA SAB SDA SI SL SN STASTK STR TA TBA TC TDA TIP TEA TL UAA ULN UPCXR ZN ZTX + daily arrival of new numbers.

ALSO RESISTORS*CAPACITORS*CHOKES'CABLESLEADS*CONNECTORS* VIDEO HEADS*DRIVE BELTSSWITCHES*TTL*CMOS*OP AMPS *VOLTAGE REGSSPECIAL FUNCTION* TRANSFORMERS ETC ETC ETC

WE SPECIALISE IN PHONE & FAX MAIL ORDERSVIBY CREDIT CARD

Callers & Mail orders welcome

CRICKLEWOOD ELECTRONICS40 CRICKLEWOOD BROADWAY LONDON NW2 3ETTEL 081 452 0161 & 081 450 0995 FAX 081 208 1441

CATALOGUE DUE OUT AUTUMN 1994

NIMBI


64

Use your electronics know-how tocreate great sound!Speaker Builder, the world's only loudspeaker

4,...-::-......71............,

magazine in English, can show you how to achieve trrexcellence in sound from your stereo system.Whether you're modifying and improving yourpresent speakers or building a new design fromscratch, Speaker Builder contains the latest inloudspeaker technology. Within its pages, learn ,,about Thiele -Small design software, build an in-expensive measurement mike good enough for theprofessionals, or simply indulge in reading aboutthe experiences of others using their technicalskills to improve the sound around them.

Since 1980, Speaker Builder has been exploringboth the traditional and more unusual formats for loudspeakers. From pipes tocorrugated boxes to transmission lines and electrostatics, every conceivablemedium is discussed. An international forum for speaker enthusiasts the worldover, sharing ideas and designs, Speaker Builder has made it possible forthousands to enjoy the highest quality sound without straining their budgets.

The publishers of Speaker Builder invite you to use your electronics know-how todiscover the world of better sound. To subscribe, simply return the form below withyour payment or FAX your credit card order and receive 8 issuesof Speaker Builderfor a low introductory rate of $45 for a one- year subscription. That's a $5 savingsoff the regular overseas airmailed rate. Or you may subscribe for two years at $80($10 off).

U One Year $45 U 2 Years $80Remittances in US funds drawn on a US bank only.

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PIC - PIC - PICThe Book - A Beginners Guide to theMicrochip PICHardware Starter KitsProject PacksMicrochip Approved Training CoursesConsultancy

For further information contact: -Bluebird ElectronicsClayshore House, 150 High St., Worton,Devizes, Wilts. Phone/Fax 0380 725110

IF ANADVERT IS WRONG,

WHO PUTS IT RIGHT?We do. The Advertising Standards Authority ensures

advertisements meet with the strict Code of Advertisii g Practice.So if you question an advertiser, they have to

answer to us.lb find out more about the ASA, please write to

Advertising Standards AuthorityDepartment X. Brook House,

Torrington Place, London WCIE 7HN.

This space Is donated In the Interests of high standards in advertisements.

COMPONENTSSELECT

New circuit protectorsRaychem has introduced newversions of its resettable sur-face -mount Polyswitch circuitprotection devices for electronicapplications, including com-puter interface ports and pe-ripherals. Current ratings from300 mA to 2.5 A, voltage rat-ings 15-69 V and resistanceratings as low as 100 mQ.Raychem Ltd, Faraday Road,Dorcan, Swindon SN3 5HH.Telephone 01793 528 171Fax 01793 572 276.

70 ns sample -and -holdA monolithic sample -and -holdamplifier that can enhance ana-logue -to -digital conversion totalharmonic distortion by 5-10 dBto let designers use lower costADCs and stiull meet systempereformance objectives is nowavailable fromHarris Semiconductor, River-side Way, Camberley GU15 3YQTelephone 01276 686 886Fax 01276 682 323

Reed relaysReliable switching is providedby Series 182A and Series 182Cmoulded reed relays that areavailable with 5 V, 12 V and24 V d. c. nominal coil voltagesand 2000 V coil/contact break-down voltage. Switch ratingsfor Series 182A are 240 V a.c300 V d.c. , 500 mA, 10 W; forSeries 182C: 200V d.c., 250 mA,3 W. The max. initial contactresistance is 200 nic2 in bothseries.AX Electronic ComponentDistribution, Unit 22, LawsonHunt Industrial Park, GuildfordRoad, Broadbridge Heath,Horsham RH12 3JR. Phone01403 240 055. Fax 01403255 657.

New range of controllersA new micromodule, 16/32 bit,68 k controller measuring100x118 mm contains a proto-typing area on which users canadd their own circuitry for thosespecial jobs. Applications aredeveloped on a PC, down loadedto the module and tested in RAMor EEROM memory. Up to1 Mbyte propgram space is avail-able on board with up to 512 kSRAM. This product will be of

particular interest to all 8 bitusers who may be running outof power or memory. The oneoff price is £95.Cambridge MicroprocessorSystems Ltd, Unit 17-18 Zone`D', Chelmsford Road Ind.Estate, Great Dummow, EssexCM6 1XG. Telephone 01371875 644. Fax 01371 876 077.

Intelligent multi -functiondigital panel meters

New panel meters from ITT, theDPM Series, are available in24 mm and 48 mm high vers-dions. Each has 34 standardranges for the measurement ofvoltage, current and tempera-ture.ITT Instruments, Jays Close,Viables Estate, BasingstokeRG22 4BW. Phone 01256311 877. Fax 01256 23659.

New control knobsA range of new control knobsis available from Rendar, in-cluding both plain and gradu-ated types.Rendar Ltd, Durban Road,South Bersted, Bognor RegisP022 9RL. Telephone 01243866 741. Fax 01243 841486.

New SMD crystalA new surface -mount crystal ,Type CX89F, from ACT has alow profile body that is 5_1.8 mmhigh. It provides up to 0.5 mWdrive and is available in the fre-quency range 12-100 MHz.Advanced Crystal Technology,9 Kingfisher Court, HambridgeRoad, Newbury RG14 5SJ.Telephone 01635 528 520Fax 01635 528 443.

Low charge HEXPETsInternational Rectifier has an-nounced a development in itspower MOSFET process tech-nology that has reduced thegate charge by up to 40% andthe Miller capacitance of itsHEXFET power transistors byup to 85%. The new low -chargeHEXFETs'E offer designers ofpower switching equipment alower cost and simpler methodfor driving transistors at a givenfrequency. Moreover, this im-provement has been achievedwithout any effect on other de-vice parameters and at no extracost.International Rectifier, Hol-land Road, Hurst Green, OxtedRH8 9BB. Telephone 01883713215. Fax 01883714234.



SURVEILLANCEPIUWESSNEVAL Malin KITS

Whether your requirement for surveillance equipment is amateur, professional or you are just fascinated by this unique area ofelectronics SUMA DESIGNS has a kit to fit the bill. We have been designing electronic surveillance equipment for over 12 yearsand you can be sure that all our kits are very well tried, tested and proven and come complete with full instructions, circuitdiagrams, assembly details and all high quality components including fibreglass PCB. Unless otherwise stated all transmittersare tuneable and can be received on an ordinary VHF FM radio.

Genuine SUMA kits available only direct from Suma Designs. Beware inferior imitations!UTX Ultra -miniature Room TransmitterSmallest room transmitter kit in the word! Incredible 10mm x 20mm including mic.3-12V operation. 500m range £16.45

MT)( Micro -miniature Room TransmitterBest-selling micro -miniature Room TransmitterJust 17mm x 17mm including mic. 3-12V operation. 1000m range £13.45

STX High-performance Room TransmitterHi performance transmitter with a buffered output stage for greater stability and range.Measures 22mm x 22mm including mic. 6-12V operation, 1500m range £15.45

VT500 High -power Room TransmitterPowerful 250mW output providing excellent range and performance. Size 20mm x40mm. 9-12V operation. 3000m range £16.45

VXT Voice Activated TransmitterTriggers only when sounds are detected. Very low standby current. Variable sensitivityand delay with LED indicator. Size 20mm x 67mm. 9V operation. 1000m range £19.45

HVX400 Mains Powered Room TransmitterConnects directly to 240V AC supply for long-term monitoring. Size 30mm x 35mm.500m range £19.45

SCRX Subcarrier Scrambled Room Transmitter

Scrambled output from this transmitter cannot be monitored without the SCDM decoderconnected to the receiver. Size 20mm x 67mm. 9V operation. 1000m range £22.95SCLX Subcarrier Telephone TransmitterConnects to telephone line anywhere, requires no batteries. Output scrambled sorequires SCDM connected to receiver. Size 32mm x 37mm. 1000m range £23.95

SCOM Subcarrier Decoder Unit for SCRXConnects to receiver earphone socket and provides decoded audio output toheadphones. Size 32mm x 70mm. 9-12V operation £22.95

ATR2 Micro Site Telephone Recording InterfaceConnects between telephone line (anywhere) and cassette recorder. Switches tapeautomatically as phone is used. All conversations recorded. Size 16mm x 32mm.Powered from line £13.45

*** Specials ***OLDUBLRX Radio Control SwitchRemote control anything around your home or garden, outside lights, alarms, pagingsystem etc. System consists of a small VHF transmitter with digital encoder and receiverunit with decoder and relay output, momentary or alternate, 8 -way dil switches on bothboards set your own unique security code. TX size 45mm x 45mm. RX size 35mm x90mm. Both 9V operation. Range up to 200m.Complete System (2 kits) £50.95Individual Transmitter DLTX £19.95Individual Receiver DLRX £37.95

MOX-1 Micro BroadcasterNot technically a surveillance device but a great idea! Connects to the headphone outputof your Hi-Fi, tape or CD and transmits Hi-Fi quality to a nearby radio. Listen to yourfavourite music anywhere around the house, garden, in the bath or in the garage andyou don't have to put up with the DJ's choice and boring waffle. Size 27mm x 60mm.9V operation. 250m range £20.95

a

UTLX Ultra -miniature Telephone TransmitterSmallest telephone transmitter kit available. Incredible size of 10mm x 20mmlConnects to line (anywhere) and switches on and off with phone use.All conversation transmitted, Powered from line. 500m range £15.95

TLX700 Micro -miniature Telephone TransmitterBest-selling telephone transmitter. Being 20mm x 20mm it is easier to assemble thanUTLX. Connects to line (anywhere) and switches on and off with phone use. Allconversations transmitted. Powered from line. 1000m range £13.45

STLX High-performance Telephone TransmitterHigh performance transmitter with buffered output stage providing excellent stabilityand performance. Connects to line (anywhere) and switches on and off with phone use.AU conversations transmitted. Powered from line. Size 22mm x 22mm.1500m range £16.45

TKX900 Signalling/Tracking TransmitterTransmits a continous stream of audio pulses with variable tone and rate. Ideal forsignalling or tracking purposes. High power output giving range up to 3000m. Size25mm x 63mm. 9V operation £22.95

CD400 Pocket Bug Detector/LocatorLED and piezo bleeper pulse slowly, rate of pulse and pitch of tome increase as youapproach signal. Gain control allows pinpointing of source. Size 45mm x 54mm. 9Voperation £30.95

CD600 Professional Bug Detector/LocatorMulticolour readout of signal strength with variable rate bleeper and variable sensitivityused to detect and locate hidden transmitters. Switch to AUDIO CONFORM mode todistinguish between localised bug transmission and normal legitimate signals such aspagers, cellular, taxis etc. Size 70mm x 100mm. 9V operation £50.95

QTX180 Crystal Controlled Room TransmitterNarrow band FM transmitter for the ultimate in privacy. Operates on 180 MHz andrequires the use of a scanner receiver or our ORX180 kit (see catlogue). Size 20mm x67mm. 9V operation. 1000m range £40.95

(11.X181) Crystal Cointrolled Telephone TransmitterAs per OTX180 but connects to telephone line to monitor both sides of conversations.20mm x 67mm. 9V operation. 1000m range £40.95

QSX180 Line Powered Crystal Controlled Phone TransmitterAs per OLX180 but draws power requirements from line. No batteries required. Size32mm x 37mm. Range 500m £35.95

011X180 Crystal Controlled FM ReceiverFor monitoring any of the '0' range transmitters. High sensitivity unit. All RF sectionsupplied as a pre -built and aligned module ready to connect on board so no difficultysetting up. Outpt to headphones. 60mm x 75mm. 9V operation £60.95

A build-up service is available on all our kits if required.UK customers please send cheques, POs or registered cash. Please add£1.50 per order for P&P. Goods despatched ASAP allowing for chequeclearance. Overseas customers send sterling bank draft and add £5.00 perorder for shipment. Credit card orders welcomed on 0827 714476.

OUR LATEST CATALOGUE CONTAINING MANY MORE NEWSURVEILLANCE KITS NOW AVAILABLE. SEND TWO FIRSTCLASS STAMPS OR OVERSEAS SEND TWO IRCS.

9



PC PAL VGA TO TV CONVERTERConverts a colour TV intoa basic VGA screen. Complete with built in psu, lead and sAvare.£49.95. Meal for laptops or a cheap upgrade.EMERGENCY LIGHTING UNIT Complete unit with 2 doublebulb floodlights, built in charger and auto switch. Fully cased. 6v 8AHlead acid req'd. (secondhand) £4 ref MAG4P11.GUIDED MISSILE WIRE. 4200 metre reel of ultra thin 4 coreinsulated cable, 281bs breaking strain, less than 1mm thick! Idealalarms, intercoms, fishing, dolls houses etc. £14.99 ref MAG15P5

SINCLAIR C6 13" WHEELS Complete with centre bearing(cycle type), tyre and inner tube. £6 ea ref MAG 6P10. Ideal go kart300v PANEL M ETER 70X60X50MKAC, 90 degree scale. Goodquality meter. £5.99 ref MAG 6P14 Ideal for monitoring mains etc.ASTEC SWITCHED MODE PSU BM41012 Gives +5 e 3.75A,+12g1.5A,[email protected] 230/110. cased, 5M41012. £5.99 ref AUG6P3.TORRODIAL TX 30-0-30 480VA, Perfect for Mosfet amplifiersetc. 120mm dia 55mm thick E18.99 ref AP R19.AUTO SU NCHARGER 155x300mm solar panel with diode and3 metre lead fitted with a dgar plug. 12v 2watt. £9.99 ea ref AUGTOP3,FLOPPY DISCS DSDD Tog/ quality 5.25' discs, these have beenwritten to once and are unused. Pack of 20 is £4 ref AUG4P1.MOD WIRE Perfect for repairing PCB's, wire wrap etc. Thininsulated wire on 500m reels. Our price just £9.99 ref APR10P8.12v MOVING Lin HT Controller. Made by Hella, 6 channels ratedat 90ivatts each. Speed cored, cased. £34.99 ref APR35.ECLATRON FLASH TUBE As used in police car flashing lightsetc, full spec supplied, 60-100 flashes a min. £9.99 ref APR1OP5.24v AC 96WATT Cased power supply. New. £13.99 ref APR14.MILITARY SPEC GEIGER COUNTERS Unused and straightfrom Her majesty's forces, £50 ref MAG 50P3.STETHOSCOPE Fully functioning stethoscope, ideal for listeni ngto hearts, pipes, motors etc. £6 ref MAR6P6.OUTDOOR SOLAR PATH LIGHT Captures sunlight duringthe day and automatically switches on a built in lamp at dusk.Complete with seales lead acid battery elc.£19.99 ref MAR20P1.ALARM VERSION Of above unit comes with built in alarm and pirto deter intruders. Good value at just £24.99 ref MAR25P4.CLOCKMAKER KIT Hours of fun making your own clock, com-plete instructions and everything you need, E7.99 ref MAR8P2.CA RETAKE R VO LUM ET RIC Alarm, will cover the w hde of theground floor against forcred entry. Includes mains power supply andintegral battery backup. Powerful internal sounder, will take extemalbell if req'd. Retail E150+, ours? £49.99 ref MAR50P1.TELEPHONE CABLE White 6 core 100m reel complete with apack of 100 dips. Ideal 'phone extns etc. E7.99 ref MAR8P3.

IBM PC CASE AND PSU Ideal base for building your own PC.Ex equipment but OK. £9.99 each REF: JUN10P2,MICRODRIVE STRIPPER Small cased tape drives ideal forstripping, lots of useful goodies induding a smart case, and lots ofcomponents £2 each ref JUN2P3.SOLAR POWER LAB SPECIAL You get TVV06"x6' 6V 130mAsolarcells, 4 LED's, wire, buzzer, switch plus 1 relay or motorSuperbvalue kit just £5.99 REF: MAG6P8SOLID STATE RELAYS Will switch 25A mains. Input 3.5.26vDC 57x43x21mm with terminal screws £3.99 REF MAG4P 10300DPIA4 DTP MONITOR Brand new but shop soiled so hencebargain priceITTUECL inputs. 15' landscape, 1200x1664 pixelcomplete with circuit diag to help you interface with your projects,JUST £14.99 REF JUN 1 5P2.MULTICORE CABLE 300 metre reef of grey 8 core cable idealfor 'phones, intercomms, computers, alarms etc. Comes inspedaldispensing container to avoid tangles. £15 ref AUG15.BUGGING TAPE RECORDER Small voice activated recorder,usesmicro cassette canpletewith headphones £28.99 ref MAR29P 1.

U LT RAM IN I BUG M IC 6mmx3.5mm made byAKG,.5- 12v electretcondenser, Cost £12 ea, Our? four for £9.99 REF MAG1OP2.RGB/CGA/EGA/TTL COLOUR MONITORS 12' in goodcondition. Back anodised metal case. E79 each REF JUN79GX4000 GAMES MACHINES returns sock for spares or repair£9 each (no games). REF MAG9P1C64 COMPUTERS Retums, so ok for spares etc £9 ret MAG9P2FUSELAGE LIGHTS 3 foot by 4' panel 1/8' thick with 3 panelsthat glow green when a voltage is applied. Good for night lights,frontpanels, signsaisco etc. 50-100v per strip. £25 ref MAG25P2ANSWER PHONES Returns w ith 2 faults, we give you the bitsfor1 fault. you have to find the other yourself. ST Response 200's £18ea REF MAG18P1. PSU £5 ref MAG5P12.SWITCHED MODE PSU ex equip, 60w +5v @5A, -5vQ.5A,+12v@2A,[email protected] 120/220v cased 245x88x55mm IECinputsocket £6.99 REF MAG7P1PLUG IN PSU 9V 200mA DC £2.99 each REF MAG3P9PLUG IN ACORN PSU 19v AC 14w , £2.99 REF MAG3P 10POWER SUPPLY fully cased with mains and o/p leads 17v DC900mA output. Bargain price £5.99 ref MAG6P9ACORN ARCH MA EDES PSU +5v @. 4.4A. on/off sw uncased,selectable mains input, 145x100x45mm E7 REF MAG7P2GEIGER COUNTER KIT Low cost professional twin tube, com-plete with PCB and components. Now only £19 REF AUG19.9v DC POWER SUPPLY Standard plug in type 150ma 9v DCwith lead and DC power plug. price for two is £2.99 ref AUG3P4.AA NICAD PACK encapsulated pack of 8 AA nicad batteries(tagged) ex equip, 55x32x32mm. £3 a pack. REF MAG3PII13.8V 1.9A psu cased with leads. Just £909 REF MAGIOP3360K 6.26 brand new half height floppy drives IBMcompatibleindustry standard. Just £699 REF MAG7P3PPC MODEM CARDS. These are high spec plug in cards madefor the Amstrad laptop computers, 2400 baud dial up unit completewith leads. Clearance price is E5 REF: MAG5P1INFRA RED REMOTE CONTROLLERS Originally made forhi spec satellite equipment but perfect for all sorts of remote controlprojects. Our clearance price is just £2 REF: MAG2TOWERS INTERNATIONAL TRANSISTORGU IDE. Averyuseful book for finding equivalent transistors, leadouts, specs etc.£20 REF: MAG20P1SINCLAIR C6 MOTORS We have a few left without gearboxes.

NEW BULL ELECTRONICS STORE IN

WOLVERHAMPTON55A WORCESTER ST TEL 0902 22039

Spec is12v DC 3,3001pm £25 ref MAG25.

NEW PRODUCT200 WATT INVERTER Converts 10-15v DC intoeither 110v or 240v AC. Fully cased115x 36x 156m m, complete with heavy duty powerlead, cigar plug, AC outlet socket.Auto overloadshutdown, auto short circuitshutdown, auto inputover voltage shutdown, auto input under voltageshutdown (with audible alarm), auto temp control,unit shuts down if overheated and sounds audiblealarm. Fused reversed polarity protected. outputfrequency within 2%, voltage within 10%. A ex-tremely well built unit at a very advantageousprice!!!Price is £64.99 ref AUG65. UNIVERSAL SPEED CONTROLLER KIT Designed by us forthe C5 motor but ok forany 12v motor up to 30A. Complete with PCBetc. A heat sink may be required. £17.00 REF: MAG17MAINSCABLE Precut black 2 core 2 metre lengths ideal forrepairs, projects etc. 50 metres for £1.99 ref AUG2P7.COMPUTER COMMUNICATIONS PACK Kit contains 100mof 6 core cable, 100 cable dips, 2 line drivers with RS232 Interfacesand all connectors etc. Ideal low cost method of communicatingbetween PC'sover a long distance. Complete kit E15.99 Ref MAR 16P2.

MINI CYCLOPS PIR 52x62x40mm runs on PP3 battery completewith shrill sounder. Cheap protection at only £5.99 ref MAR6P4.ELECTRIC MOTOR KIT Comprehensive educational kit In-cludes all you need to build an electric motor. £9.99 ref MARI OP4.

VIDEO SENDER UNIT. Transmits both audio and video signalsfrom either a video camera, video recorder, TV or Computer etc toany standard TV set in a 100' range! (tune TV to a spare channel) 12vDC op. Price /5E15 REF: MAG15 12v psu is £5 extra REF: MAG5P2FM CORDLESS MICROPHONE Small hand held unit with a500' range! 2 transmit power levels. Reqs PP3 9v battery. Tuneableto any FM receiver. Price is £15 REF: MAG15P1LOW COST WALKIE TALKIES Pair of battery operated unitswith a range of about 200'. Ideal for garden use or as an educationaltoy. Price is £8 a pair REF: MAG 8P1 2 x PP3 req'd.*MINATU RE RADIO TRANSCEIVERS A pair of walkie talkieswith a range of up to 2 kilometres in open country. Units measure22x52x155mm. Complete with cases and earpieces. 2xPP3 req'd.£30.00 pair REF: MAG30COMPOSITE VIDEO KIT. Converts composite video into sepa-rate H sync, V sync, and video. 12v DC. £8.00 REF: MAG8P2.LO3600 PRINTER ASSEMBLIES Made by Amstrad they areentire mechanical printer assemblies including printhead, steppermotors etc etc In fact everything bar the case and electronics, a goodstripper! £5 REF: MAG5P3 or 2 for £8 REF: MAG8P3SPEAKER WIRE Brown 2 core 100 foot hank £2 REF: MAG2P1LED PACK of 100 standard red 5m Weds E5 REF MAG5P4

UNIVERSAL PC POWER SUPPLY complete with flyleads,switch, fan etc. Two types available 150w at £15 REF:MAG15P2(23x23x23mm) and 200w at £20 REF: MAG20P3 (23)23)23mm)*FM TRANSMITTER housed in a standard working 13A adapter!!the bug runs directly off the mains so lasts forever! why pay £7007 orprice is £26 REF: MAG26 Transmits to any FM radio.*FM BUG KIT New design with PCB embedded coil for extrastability. Works to any FM radio. 9v battery req'd. £5 REF: MAG5P5*FM BUG BUILT AND TESTED superior design to kit. Suppliedto detective agencies. 9v battery req'd. £14 REF: MAG14TALKING COIN BOX STRIPPER originally m ade to retail at E79each, these units are designed to convert and ordinary phone into apayphone. The units have the locksmissing and sometimes brokenhinges. Howeverthey can be adapted for their original use or used forsomething else?? Price is just 1E3 REF: MAG3P1100 WATT MOSFET PAIR Same spec as 2SK 343 and 2SJ413(8A,140v,100w) 1 N channel, 1 P channel, £3 a pair REF: MAG3P2TOP QUALITY SPEAKERS Made for HI Fl televisions these are10 watt 4R Jap made 4' round with large shielded magnets. Goodquality. £2 each REF: MAG2P4 or 4 for £6 REF: MAG8P2TWEETERS 2' diameter good quality tweeter 140R (ok with theabove speaker) 2 for E2 REF: MAG2P5 or 4 for £3 REF: MAG3P4AT KEYBOARDS Made by Apricot these quality keyboards needjust a small mod to run on any AT, they work perfectly but you will haveto put up with 1 or 2 foreign keycaps! Price £6 REF: MAG6P3PC CASES AgaI n mixed types so you take a chance next one off thepile £12 REF:MAG12 or two the same for £20 REF: MAG20P4HEADPHONES Ex Virgin Atlantic. Boers for£2 REF: MAG2P8PROXIMITY SENSORS These are small PCB's with what looklike a source and sensor LED on one end and lots of components onthe rest of the PCB. Completewith fly leads. Pack of 5£3 REF: MAG:3P5 or 20 for ES REF: MAGBP4

'SOME OF OUR PRODUCTS MAY BE UNLICENSABLE IN THE UK

BULL ELECTRICAL250 PORTLAND ROAD HOVE SUSSEX

EN3 5QTMAIL ORDER TERMS: CASH PO OR CHEQUEWITH ORDER PLUS £3.00 POST PLUS VAT.

PLEASE ALLOW 7 -10 DAYS FOR DELIVERYelTELEPHONE ORDERS WELCOME

' TEL: 0273 203500FAX: 0273 323077

SNOOPERS EAR? Original made to clip over the earpiece oftelephone to amplify the sound -it also works quite well on the cablerunning along the wall! Price is E5 REF: MAG5P7DOS PACKS Microsoft version 3.3 or higher complete with allmanuals or price just £5 REF: MAG5P8 Worth It just for the verycomprehensive manual! 5.25' only.DOS PACK Microsoft version 5 Original software but no manualshence only £3 REF: MAG3P6 5.25' only.PIR DETECTOR Made by famous UK alarm manufacturer theseare hi spec, long range internal units. 12v operation. Slight marks oncase and unboxed (although brand new) £8 REF: MAGBP5WINDUP SOLAR POWERED RADIO AM/FM radio completewith hand charger and solar panel! £14 REF: MAG14P1MOBILECARPHONE£6.99 Well almost! completein carphoneexduding the box of electronics normally hidden under seat Can bemade to Illuminate with 12v also has built in light sensor so displayonly illuminates when dark. Totally convincing! REF: MAG6P6ALARM BEACONS Zenon strobe made to mount on an externalbell box but could be used for caravans etc. 12v operation. Justconnect up and it flashes regularly) E5 REF: MAG5P11FIRE ALARM CONTROL PANEL High quality metal casedalum panel 350x165x80mm.With key. Comes with electronics butno information. sale price 7.99 REF: MAG8P6REMOTE CONTROL PCB These are receiverboards for garagedoor opening systems. Another use? £4 ea REF: MAG4P56"X12" AMORPHOUS SOLAR PANEL 12v 155x310mm130mA. Bargain price just £5,99 ea REF MAG6P12.FIBRE OPTIC CABLE BUMPER PACK 10 metres for E4.99ref MAG5P 13 ideal for experimenters! 30 m for £12.99 ref MAG13P 1LOPTX Line output transformers believed to be for IBM hi res colourmonitors but useful for getting high voltages from low ones! £2 eachREF: MAG2P12 bumper pack of 10 for £12 REF. MAG12P3,

H EATSIN KS (finned) T0220, designed to mount vertically on a pcb50x40x25mm you can have a pack of 4 for £1 ref JUN 1P11,WATERPROOF JU NCTION BOX 65mm dia 33mm deep. Fourcable entry exit points (adjustable for any size cable) snap ft Ild. Idealfor TV, satellite use. £2 ea ref APR2 or 6 for EIO ref APR10P7.

BOTH SHOPS OPEN 9-5.30SIX DAYS A WEEK

INFRARED LASER NIGHT SCOPESSecond generation image intensifiercomplete with hand grip attachmentwith built in adjustable laser lamp forzero light conditions. Supplied withPentax 42mm camera mount andnormal eye piece. 1 .6kg, uses1xPP3,3xAA's (all supplied )C245+VatNEW HIGH POWER LASERS15mW, Helium neon, 3 switchablewave lengths .63um,1.15um,3.39um(2 of them are infrared) 500:1 polarizerbuilt in so good for holography. Sup-plied complete with mains powersupply.790x65mm. Use with EX-TREME CAUTION AND UNDERQUALIFIED GUIDANCE. L349+Vat.£££££££WE BUY SURPLUS STOCKELLM£

TURN YOUR SURPLUS STOCK INTO CASH.IMMEDIATE SETTLEMENT. WE WILL ALSO QUOTE FOR

COMPLETE FACTORY CLEARANCE

1994 CATALOGUE.MINIMUM GOODS ORDER ES 00 TRADE ORDERS FROM GOVERNMEM , SCHOOLS,UNIVERSITIES.i LOCAL AUTHORITIES WELCOME AL L GOODSSUPPL IEDSUBJECTTOOUR CONDITIONS OF SALE AND UNLESS OTHERWISE ST AT ED GUARANTEED FOR 30DAYS RIGHTS RESERVED TO CHANGE PRICES A SPECIFICATIONS WITHOUT PRIORNOTICE ORDERS SUBJECT TO STOCK QUOTATIONS W TLINGLY GIVEN FOR QUAFFTITLES HIGHER THAN THOSE STATED

3FT X 1FT IOWATT SOLAR PANELS14.5v/700mA

£33.95(PLUS 5200 SPECIAL PACKAGING CHARGE)

TOP QUALITY AMORPHOUS SILICON CELLS HAVE ALMOST ATIMELESS LIFESPAN WITH AN INFINITE NUMBER OF POSSIBLE AP.PLICATIONS, SOME OF WHICH MAY BE CAR BATTERY CHARG-ING, FOR USE ON BOATS OR CARAVANS, OR ANYWHERE APORTABLE 12V SUPPLY IS REQUIRED. REF: MAG34

PORTABLE RADIATION DETECTOR

£49.99A Hand held personal Gamma and X Ray detec-tor. This unit contains two Geiger Tubes, has a 4digit LCD display with a Piezo speaker, giving anaudio visual indication, The unit detects highenergy electromagnetic quanta with an energyfrom 30K eV to over 1.2M eV and a measuringrange of 5-9999 UR/h or 10-99990 Nr/h. Suppliedcomplete with handbook.Ref MAG50.


Low cost data acquisition for IBM PCs & compatibles

A unique range of easy to use data acquisition products designed for use with IBM compatiblecomputers. Combined with the software they allow your PC to be used as a host of useful test andmeasurement instruments, or as an advanced data logger.Installed in seconds they simply plug into the parallel port (except the ADC -16 which connects to theserial port). They are self-contained, require no power supply and take up no expansion slots.Each device comes with a comprehensive manual. Software drivers are included for users who wishto write their own software. Software supplied on 3.5" disk.

PicoScope

MIMEMOMIBMS

Storage oscilloscope withtrigger, timebase, rulers andoffset functions. Real timespectrum analysis withmin/max frequency andsignal averaging. Multiplemeters on screen (digitaland bargraph). Printer andfile handling support.

`Virtual instrument' software package.

NEW ''eioo Virtual InstrumentDual Channel 12 -bit resolutionThe ADC 100 offers both a highsampling rate (100kHz) and a highresolution, It is ideal as a generalpurpose test instrument either in thelab or in the field. A flexible inputrange (±200mV to ±20V) allows theunit to connect directly to a widevariety of signals.

with PicoScope £199PicoScope & PicoLog £209

4

PicoLog Collect, store, display and printdata from 1 sample per ms to 1per day. Record average,min/max values or scaled values(linear, equation, table look-up).Report types: monitor (withmin/max alarms), y -t graphs, x -ygraphs, tabulation.

Advanced data logging software package

qCZ

NEWfrom

PICO

Digital Storage Scope Spectrum Analyser Voltmeter Frequency Meter Chart Recorder Data Logger

147,e /01 Channel 8 -bit

Lowest cost Up to 22kHz sampling 0-5V input rangeThe ADC 10 gives yourcomputer a single channel ofanalogue input. Simply pluginto the parallel port andyou're ready to go.

'toe /0 withPicoScope £49

PicoScope andPicoLog £59

feve ll11 Channel 10 -bit

Digital output Up to 18kHz sampling 0-2.5V input rangeThe ADC 11 provides 11channels of analogue inputin a case slightly larger thana matchbox. It is ideal forportable data logging using a'notebook' computer.

"eve /0 withPicoScope £85


"fve /21 Channel 12 -bit

High resolution Up to 18kHz sampling 0-5V input rangeThe ADC 12 is similar to theADC 10 but offers animproved 12 -bit (1 part in4096) resolution comparedto the ADC 10's 8 -bit (1 partin 256).

"Me /2 withPicoScope £85


/dove /68 Channel 16 -bit + sign Highest resolution 2Hz sampling - 16 -bit ± 2.5V input rangeThe ADC 16 has the highestresolution of the range, it iscapable of detecting signalchanges as small as 40pV.Pairs of input channels canbe used differentially toreject noise. Connects to theserial port.

,47,e /6 withPicoLog £115

PicoLog for ADC 10/11/12 £25. Oscilloscope Probes (x1, x10) £10. Carriage UK free. Overseas £6

VISA

00

Pico Technology Ltd. Broadway House, 149-151 St Neots Road, Hardwick, Cambridge CB3 70J, UK

TEL : 0954-211716 FAX : 0954-21s

Phone or FAX for sales, ordering information, data sheets, technical support. All prices exclusive of VAT.



11 HART AUDIO KITS -YOUR VALUE FOR00' MONEY ROUTE TO ULTIMATE HI-FIHART KITS give you the opportunity to build thevery best engineered hifi equipment there is,designed by the leaders in their field, using thebest components that are available.Every HART KIT is not just a new equipment ac-quisition but a valuable investment in knowledge,giving you guided hands-on experience of modernelectronic techniques.In short HART is your 'friend in the trade' givingyou, as a knowledgeable constructor, access tobetter equipment at lower prices than the man inthe street.You can buy the reprints and construction manualfor any kit to see how easy it is to build your ownequipment the HART way. The FULL cost can becredited against your subsequent kit purchase.Our list will give you fuller details of all our AudioKits, components and special offers.

AUDIO DESIGN 80 WATT POWER AMPLIFIER.

This fantastic John Linsley Hood designedamplifier is the flagship of our range, and the idealpowerhouse for your ultimate hifi system. This kitis your way to get £K performance for a few tenthsof the cost!. Featured on the front cover of'Electronics Today International' this completestereo power amplifier offers World Class perfor-mance allied to the famous HART quality and easeof construction. John Linsley Hood's comments onseeing a complete unit were enthusiastic:- "Theexternal view is that of a thoroughly professionalpiece of audio gear, neat elegant and functional.This impression is greatly reinforced by theinternal appearance, which is redolent of quality,both in components and in layout." Optionsinclude a stereo LED power meter and a versatilepassive front end giving switched inputs usingALPS precision, low -noise volume and balancecontrols. A new relay switched front end optionalso gives a tape input and output facility so thatfor use with tuners, tape and CD players, orindeed any other 'flat' inputs the power amplifiermay be used on its own, without the need for anyexternal signal handling stages. 'Slave' and'monobloc' versions without the passive inputstage and power meter are also available. Allversions fit within our standard 420 x 260 x 75mmcase to match our 400 Series Tuner range. ALL sixpower supply rails are fully stabilised, and thecomplete power supply, using a toroidal trans-former, is contained within a heavy gaugealuminium chassis/heatsink fitted with IEC mainsinput and output sockets. All the circuitry is onprofessional grade printed circuit boards withroller tinned finish and green solder resist on thecomponent ident side, the power amplifiersfeature an advanced double sided layout formaximum performance. All wiring in this kit is pre-terminated, ready for instant use!RLH11 Reprints of latest articles E1.80K1100CM HART Construction Manual £5.50

LINSLEY HOOD 1400 SERIESULTRA HIGH -QUALITY PREAMP

Joining our magnificent 80 Watt power amplifiernow is the most advanced preamplifier ever of-fered on the kit, or indeed made-up marketplace.Facilities include separate tape signal selectionto enable you to listen to one programme whilerecording another, up to 7 inputs, cross record-ing facilities, class A headphone amplifier, can-cellable 3 -level tone controls and many other use-ful functions, all selected by high quality relays.For full details see our list.

LINSLEY HOOD 'SHUNT FEEDBACK' R.I.A.A.MOVING COIL & MOVING MAGNET

PICKUP PREAMPLIFIERS

Modern, ultimate sound systems are evolvingtowards built-in preamplifiers within or near theturntable unit. This keeps noise pickup and trebleloss to a minimum. We now offer two units, bothhaving the sonically preferred shunt feedbackconfiguration to give an accurate and musicalsound, and both having the ability to use bothmoving magnet and moving coil cartridges.Kit K1500 uses modern integrated circuits toachieve outstanding sound quality at minimal cost.The very low power requirements enable this unit tobe operated from dry batteries and the kit comeswith very detailed instructions making it ideal for thebeginner. K1500 Complete kit with ail components,printed circuit board, full instructions and fullyfinished case £67.99Instructions only £2.80Kit K1450 is a fully discrete component implementa-tion of the shunt feedback concept and used with theright cartridge offers the discerning user the ul-timate in sound quality from vinyl disks. Can befitted inside our 1400 Preamp, used externally or asa standalone unit. It has a higher power require-ment and needs to be powered from our 1400 Seriespreamplifier or its own dedicated power supply.K1450 Complete Discrete Component RIAA PhonoPreamp £109.58Factory Assembled and Tested £159.58K1565 Matching Audio Grade Power Supply withpotted toroidal transformer and limited shiftearthing system £79.42Factory Assembled and Tested £118.42U1115 Power Interconnect Cable £7.29

SPECIAL OFFERPRECISION Triple Purpose TEST

CASSETTE TC1DD.Are you sure your tape recorder is set up to give itsbest? Our latest triple purpose test cassette checksthe three most important tape parameters withouttest equipment. Ideal when fitting new heads.A professional quality, digitally mastered test tapeat a price anyone can afford.Test Cassette TC1DD Our price only £10.99

DISK -COUNT Classical CD's.Top quality, Full Digital (DDD) Compact Disks of thegreat classical favourites. Like everyone else wedidn't like the idea of paying silly prices for CD's.After a long search we have now located a source oftop quality classical recordings at prices that makeyou suspect the quality- until you try them! Send forour list of titles.

TECHNICAL BOOKSHELFThe Following are a Small Selection of the Books we

Offer Full Details are in our Free List."THE ART OF LINEAR ELECTRONICS", John LinsleyHood.Just Out! Hot Off the Press, the definitive electronicsand audio book by the renowned John Linsley Hood.This 300+ page book will give you an unparalleledinsight into the workings of all types of audio circuits.Learn how to read circuit diagrams and understand

Send or 'phone for your copy of our FREE List of these and many other Kits & Components. Enquiries from Overseascustomers are equally welcome, but PLEASE send 2 IRCs if you want a list sent surface post, or 5 for Airmail.

Ordering is easy, Just write or telephone your requirements to sample the friendly and efficient HARTservice. Payment by cheque, cash or credit card. A telephoned order with your credit card number will

get your order on its way to you THAT DAY,Please add part cost of carriage and insurance as follows: -INLAND Orders up to £20 -£1.50,Orders over £20 - £3.50. Express Courier, next working day £10.

OVERSEAS - Please see the ordering information with our lists.

QUALITY 24 hr. SALES LINEAUDIO KITS (0691) 652894

amplifiers and how they are designed to give the bestsound. The virtues and vices of passive and activecomponents are examined and there are separatesections covering power supplies and the sources ofnoise and hum. As one would expect from this writerthe history and derivation of audio amplifier circuitryhave an entire chapter, as does test and measure-ment equipment.Copiously illustrated this book is incredible value forthe amount of information it contains on the muchneglected field of linear, as opposed to digital, elec-tronics. Indeed it must be destined to become thestandard reference for all who work, or are inter-ested in, this field.SPECIAL OFFER. With each book purchased you mayrequest a FREE extended index, written by theAuthor, exclusively from HART.0-7806-0868-4 £16.95Don't forget most of our kits have reprints of articles byJohn Linsley Hood that you can purchase separately.

"TOWERS' INTERNATIONAL TRANSISTORSELECTOR". This will give you the specification, pinconnections, case outline, manufacturer, equivalentsand substitutes for over 27,000 European, Americanand Japanese transistors. Latest update 4 offers over2,000 new entries plus surface mount cross index.1990 432 Pages. 247 x 173,0-572-01062-1 £19.95

"DIGITAL AUDIO AND COMPACT DISCTECHNOLOGY" 2nd Edition. Baert, Theunissenand Vergult. (SONY Europe).A thoroughly well written book covering the wholefield of recording media starting with the Phonographright through to modern professional PCM digitalrecording systems with particular and extensivecoverage on the compact disc. All aspects of therecording and reproduction processes are explainedwith separate chapters on such things as compactdisc encoding and the use of cross interleave Reed -Soloman error correction code (CIRC). This book isof course essential reading for engineers and stu-dents involved in the field but its very low pricesmakes it ideal for the enthusiast of recorded musicwho wants to know more about the hidden processesgoing on in his CD player.1992/94 248 Pages. 247 x 190.0-7506-0614-2 £17.95

"THE ART OF SOLDERING", R. Brewster,Absolutely essential reading for anyone who everpicks up a soldering iron. Written from knowledgegained in a lifetime in the field, this is the first bookever solely devoted to this essential and neglectedskill for all electronic enthusiasts. Covers everythingfrom the correct choice of soldering iron and solderto the correct procedures to follow with many illustra-tions and practical exercises.0-85935-324-3 £3.95

"HOW TO USE OSCILLOSCOPES & OTHER TESTEQUIPMENT", R.A. Penfold, 112 pages. 178 x 111.Publ. 1989.BP267 £3.50

Classics from the "Golden Age""THE WILLIAMSON AMPLIFIER", D.T.N. Williamson.In April 1947, Williamson's power amplifier, using ex-cellent -quality push/pull output valves, a special out-put transformer, and a highly filtered power supply,became an overnight success. The author takes thereader deep into his design considerations, offeringpractical advice on how to build the units plus con-cise instructions on setting up the new amp. A cultclassic.1947. Reprinted 1990, 40 Pages.0-9624-1918-4 £6.95

LOUDSPEAKERS; THE WHY AND HOW OF GOODREPRODUCTION, G.A. Briggs.This easy -to -read classic, last revised in 1949,introduces the reader to concepts such asimpedance, phons and decibels, frequencyresponse, response curves, volume and watts,resonance and vibration, cabinets and baffles,horns, room acoustics, transients, crossovers,negative feedback, Doppler and phase effects,and much more. A provocative survey of the rightquestions about sound reproduction.1949, Reprinted 1990.88 Pages. 215 x 140.0-9624-1913-3 £8.95

Postage on Single Books is £1.50 except for TheArt of Linear Electronics, Digital Audio and Com-pact Disc Technology and The Towers InternationalTransistor Selector which are £3.50. Two, or more,books are only £4.50, any size, any quantity.

ALL PRICESINCLUDEUK/EC VAT

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PRINT COMMENT READ DISK WRITE DISK DEUI NGS

" P

Connect the HANDYPROBE to the parallel printer portof the PC and start the software Measuring can becarried out at once The HANDYPROBE does not needan external power supply Some technical parameters0 5-400 V softwareselect input range,one input channel,8 bits resolution(overall accuracy 2%);A complete softwareprogram consisting ofa digitalstorage oscilloscope,spectrum analyzer,voltmeter and atransient recorderis providedThe HANDYPROBE iseminently suitable forservicing andeducational purposes.

The TP5008 is an interface cardthat provides an analogueoutput in addition to two inputchannels This output incombination with the twoinputs may be used for thesetting up of a completecontrol loop The outputmay also be used as afunction generator.The TP5008 has aresolution of 8 bitsand a sampling rateof 200,000 samples/sec (200 kHz) The input range may be set to 0.5-20 Vfull-scale deflection. The output range covers 1.25-2.5 VThe TP5008 is fitted with BNC connectors and isdelivered complete with a user manual and software.Separately available are 1:1-1:10 probesand 1 100 oscilloscope probes. 197

I I P

The HANDYSCOPE is connected to the parallel printerport This makes it possible to carry out measurementswith a laptop or notebook PC Because of its highresolution (12 bits), the HANDYSCOPE is a very accurateinstrument The measuring rate is 100,000 samples/secEither of the two channels can be set independentlyover a range of 0 5-20 V (with a 1 10 probe up to 200 V)The advanced software enables many measurements tobe carried out Two probes (switchable 1.1-1.10) areprovided The HANDYSCOPE is constructed as a smalltable model with two BNC connectorsThe length ofthe cablelinking thePC and theHANDYSCOPEis 18 m,which can beextendedto 3 8 m

TiePie engineering manufactures a completerange of computer -controlled measuring instrumentsConnecting these units to a PC (MS DOS 3 0 or higher)results in a number of compre-hensive test instruments - oscilloscope;

- voltmeter;- spectrum analyzer;- frequency meter;- transient recorder.

All measured data can be storedon disk or run off for documentation Because of themany trigger possibilities, a variety of signals can bemeasured, while the powerful software enables amultitude of measurements to be carried out in astraightforward manner Application areas includeservice, medical research, automatic test systems,research and development, and education

III OD

The TP208 is an interface cardwith a measuring speed of2x20 Megasamples/sec(8 bits) Phenomena shorterthan one millionth of asecond can still bemeasured wellThe completely digitizedtriggering ensures verystable triggering withmany triggerpossibilitiesThe TP208 has aninput range of5 mV/div to 20 V/div in 12 steps and an auto calibrationfunction Since both channels may be sampledsimultaneously, phase differences can be measuredvery accurately Even single phenomena can bemeasured since each channel has a32 KByte memory Comprehensivesoftware is provided

A I

Interested? Then write or fax fora FREE demo diskette to

INSTRUTEK (UK)28 Stephenson RoadIndustrial EstateSt Ives, Cambs PE17 4WJEngland

595

(All prices are exclusive of VAT and P&PI

Telephone 10480) 460028Fax 104801460 340

70 The publishers reserve the right to change prices without prior notification. Prices shown in this issue supersede those in previous issues. E. & O.E.

READERS SERVICESExcept in the USA and Canada, all orders, except forsubscriptions and past issues (for which see below),must be sent BY POST to our Dorchester office usingthe appropriate form opposite. Please note that wecan not deal with PERSONAL CALLERS, as no stockis carried at the editorial and administrative office.Readers in the USA and Canada should send orders,except for subscriptions (for which see below), to OldColony Sound Lab, Peterborough, whose full addressis given on the order form opposite. Please includeshipping cost according to total order value. For sur-face delivery in the USA, if order is less than $50, in-clude $3; $50+, $4. For Canada surface, if less thanUS$50, include US$5; US$50+, US$7.50. For air orother deliveries, please inquire. Please allow 4-6weeks for delivery.All other customers must add postage and packingcharges for orders up to £25.00 as follows: UK andEire £1.95; surface mail outside UK £2.45; Europe(airmail) £2.95; outside Europe (airmail) £3.70. For or-ders over £25.00, but not exceeding £100.00, thesep&p charges should be doubled. For orders over£100.00 in value, p&p charges will be advised.

SUBSCRIPTIONS & PAST ISSUES

Subscriptions and past issues, if available, should beordered from Worldwide Subscription Service Ltd,Unit 4, Gibbs Reed Farm, Pashley Road, TICE-HURST TN5 7HE, England. For subscriptions, usethe order form on the opposite page. Prices of past is-sues (except July/August and December), includingpostage for single copies, are £2.70 (UK and Eire);£3.00 (surface mail outside UK); £3.20 (air mailEurope); £3.95 (airmail outside Europe). Prices of pastJuly/August and December issues, including postagefor single copies, are £3.75 (UK); £4.00 (surface mailoutside UK); £4.25 (airmail Europe); and £5.00 (air-mail outside Europe).

PAST ARTICLESPhotocopies of articles from January 1978 onwardscan be provided, postage paid, at £1.95 (UK and Eire),£2.10 (surface mail outside UK), £2.45 (airmailEurope), or £2.70 (airmail outside Europe). In case anarticle is split into instalments, these prices are applic-able per instalment. Photocopies may be orderedfrom our editorial and administrative offices.

COMPONENTS

Components for projects appearing in Elektor Elec-tronics are usually available from appropriate advertis-ers in this magazine. If difficulties in the supply ofcomponents are envisaged, a source will normally beadvised in the article. It should be noted that thesource(s) given is (are) not exclusive - other suppli-ers may also be able to help.

BOOKS

For book availability, see advertisement on page 81.

SHELF BOX

Elektor Electronics shelf box £2.95 $6.00

FRONT PANEL FOILS

PROJECT No. Price Price(£) (US$)

4MB printer buffer card 920009-F 8.25 16.50LC meter 920012-F 11.45 22.90Guitar tuner 920033-F 8.80 17.60NICAM decoder 920035-F 8.25 16.5012VDC to 240VACinverter 920038-F 16.15 32.30

Audio DAC 920063-F 10.00 20.00Dig. audio/visual system 920022-F1 10.00 20.00

920022-F2 19.40 38.80920022-F3 28.80 57.60

1.2 GHz multifunctionfrequency meter 920095-F 13.80 27.60U2400B NiCd batterycharger 920098-F 8.75 17.50Workbench PSU 930033-F 17.00 34.00Inexpensive phase meter 930046-F 17.25 34.50Mini preamplifier 930106-F Not availableAF rms voltmeter 930108-F 17.25 34.50

PROJECT No Price(£)

Price(US$)

EPROMS / PALS / MICROCONTROLLERS

EMON51 (8051 assemblercourse) (1 x 27256+disk 1661) 6061 20.00 40.00EMON51 (8051 assemblercourse) (1 x 27256+disk 1681) 6091 20.00 40.00FM tuner (1 x 27C256) 6101 15.30 30.60Multi -purpose Z80 card:GAL set (2 x GAL 16V8) 6111 11.15 22.30Multi -purpose Z80 card:BIOS (1 x EPROM 27128) 6121 15.30 30.601.2 GHz multifunctionfrequency meter(1 x 27C256) 6141 11.45 22.90Digital audio/visual system(1 x 27C256) 6171 10.30 20.60TV test pattern generator(1 x 27256) 6151 13.00 26.00DiAV system. Package:1 x 27512; 2 x GAL; 1 xfloppy disk (MSDOS) 6181 30.50 61.00PAL test pattern generator(1 x GAL 20V8-25) 6211 9.40 18.60800535 assembler course(1 x EMON52 EPROM and1 x disk 1811) 6221 17.05 34.10Watt-hour meter (1 x 27256) 6241 10.00 20.00Four fold DAC (1 x GAL) 6251 10.75 21.50Multipurpose display decoder(1 x 2764) 6261 11.50 23.00Telephone -controlled switch(1 x 2764) 6271 14.50 29.00Relative humidity meter(1 x 2764) 6301 14.50 29.00535 card w. EPROM emulator(1 x PAL; 1 x GAL) 6311 26.00 52.00Copybit eliminator (1 x GAL16V8 and 1 x MACH110) 6321 42.25 84.50RDS decoder (1 x 27C64) 6331 14.50 29.00I2C tester (1 x GAL 6001) 6341 30.75 61.50Mains signalling system(1 x 27C64) 6371 13.25 26.508751 programmer (1 x 8751) 7061 46.40 92.80Microcontroller NiCd charger(1 x ST62E15) 7071 10.00 20.00Maxi micro clock (clock) 7081 11.50 23.00Maxi micro clock (darkroom timer) 7091 11.50 23.00Maxi micro clock (cooking timer) 7101 11.50 23.00Mini micro clock (clock) 7111 11.50 23.00Mini micro clock (darkroom timer) 7121 11.50 23.00Mini micro clock (cooking timer) 7131 11.50 23.00VHF/UHF TV tuner(1 x 87C51) 7141 25.75 51.50Microntroller-driven UART(1 x ST62T10) 7151 17.25 34.50PIC programmer(1 x PIC17C42 and 1 x disk) 7161 52.75 105.50TV line monitor(1 x PIC16C54) 946443-1 20.25 40.50MIDI swell pedal (1x27C64) 946635 13.75 27.50

DISKETTES

8051/8032 Assembler course(IBM version) 1661 7.65 15.308051/8032 Assemblercourse (Atari version) (3.5") 1681 7.65 15.30AD232 converter 1691 7.65 15.30GAL programmer (3 disks;upgrade: June 1993) 1701 11.15 22.30Multi -purpose Z80 card 1711 7.65 15.30Fuzzy Control One 1721 7.75 15.50Pascal library for MMC 1751 9.70 19.40Speech/sound memory 1771 7.65 15.30PC -aided transistor tester 1781 7.50 15.00IR receiver and DTMF decoderfor 80C32 SBC 1791 9.00 18.00800535 assembler course 1811 8.80 17.6012C opto/relay card 1821 7.65 15.30Video digitizer for PCs 1831 14.50 29.00GAL programmer for Amiga 1841 11.00 22.0012C alphanumerical display 1851 8.50 17.00Philips preamplifier 1861 8.50 17.00GAL programmer (excl. OpalJr. disks) 1881 10.75 21.50Precision clock for PCs 1871 8.50 17.00X2404 -to -8751 interfacing 1891 8.50 17.00RC5 software emulation 1901 10.75 21.50

PROJECT No. Price Price(£) (US$)

Mains signalling system 1911 9.75 19.50SIM - an 8051 simulator 1931 34.25 68.50800535 SBC extension 1941 9.75 19.50800535 SBC I2C display 946197-1 9.75 19.50Small loop antennas 1951 10.75 21.50PIC programming course 946196-1 9.75 19.50RC5 transmitter w. 800535 946199-1 9.75 19.90

PRINTED CIRCUIT BOARDSPrinted circuit boards whose number is followed by a+ sign are only available in combination with the as-sociated software item, and can not be supplied sepa-rately. The indicated price includes the software.

APRIL 1994Mains signalling system - 1

(receiver) 940021-1930123930119940022940016940034

68HC11 processor boardRS232 speedometerStroboscope lightHeadphones amplifierHalogen light dimmerRS232 interface foruniversal bus

MAY 1994Diffferential probe foroscilloscopesMains signalling system - 2(transmitter) (incl. disk1911 and EPROM 6371)Morse decoderGeneral-pupose sensormonitorTV sound to light unit

JUNE 1994800535 SBC extensionI2C bus boosterRS485 interfaceFuel consumption monitorIntelligent EPROMeraser

JULY/AUGUST 1994Gen. purpose IR volumecontrolIR controlled switchMIDI swell pedal,incl. EPROM 946635 940019-C+Charge meter 940033Water softener 944011-1Joystick -to -mouse adaptor 944040-1Discrete preamplifier 944063-1Centronics I/O interface 944067-180C451 controller board 944069-1Robust AF power amp 944075-1PC over -temperature alarm944076-11-4 MByte SIMM adaptor 944094-1Optical doorbell 944080-1PIC experimenting board 944105-1RC5 transmitter w. 800535incl. disk 946199 944106-C+Car battery monitor 936042Resettable fuse for caravans 940061

10.25 20.507.75 15.50

Not availableNot available

18.75 37.50Not available

924048 Not available

940018 7.75 15.50

940021-2+ 33.25 66.50contact Velleman distributor

916107 Not available936038 Not available

940025+940057940035940045

19.757.256.256.00

39.5014.5012.5012.00

940058-1 9.00 18.00

930099 9.00 18.00936066 9.75 19.50

26.75 53.505.75 11.506.00 12.007.00 14.008.50 17.008.75 17.50

15.00 30.009.75 19.504.25 8.50

15.50 31.006.25 12.50

17.75 35.50

13.00 26.00Not availableNot available

SEPTEMBER 1994Switchable a.c. supply 934004 6.50 13.00Anemometer & flow meter 940017 6.25 12.50Compact frequency meter 940051-1 9.00 18.00Revolution counter 940045-1 6.00 12.00

940068-1 5.50 11.00Battery monitor 940003 Not available

OCTOBER 1994Motive -battery chargerIntegrated AF amplifier

Tester for IR remotecontrolComputer PSU monitorStable dc -dc converterIn -car audio amplifier (1)TV line monitor (incl. PIC)

940083936062-1936062-2

940084-1940087940097

940078-1940065+

7.25 14.509.50 19.00

28.25 56.50

6.50 13.00Not availableNot available14.00 28.0026.25 52.50

iA list of all PCBs, software products and front panels available through the Readers Services ispublished in the March, June, September and December issues of Elektor Electronics


xr

ix

Please send this order form to *Elektor Electronics (Publishing)P.O. Box 1414Dorchester DT2 8YHENGLANDTel. (0305) 250995Fax (0305) 250996

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TERMS OF BUSINESSHOW TO PAYUnless you have an approved credit accountwith us, all orders must be accompanied bythe full payment, including postage and pack-ing charges as stated on page 70, section I.

Payment may be made by cheque drawnon a London clearing bank (but see para. 4below), postal order. VISA. ACCESS. MAS-TERCARD or EUROCARD (when paying bycredit card, the order must go to the card-holder's address). Do not send cash throughthe mail. Cheques and postal orders should becrossed and made payable to 'Elektor Electronics(Publishing)'.

Payment may also be made by direct trans-fer from a private or business Giro account toour Giro Account No. 34 152 3801 by com-pleting and sending to the National Giro Centre,in a National Giro postage paid envelope, aNational Giro transfer/deposit form. Do not sendGiro transfers direct to us, as this will delay yourorder.

If you live outside the UK, payment mayalso be made by Bankers' sterling draft drawnon a London clearing hank, Eurocheque madeout in pounds sterling (with holder's guaran-tee card number written on the back), or US orCanadian dollar cheque, but such cheques, ac-cepted at the exchange rate prevailing at the timeyour order is received, must be increased bythe equivalent of £15.00 to cover our bankers'negotiating fee.

If you pay by Bankers' sterling draft. makeclear to the issuing bank that your full nameand address MUST he communicated to theLondon clearing bank.

Our bankers are National WestminsterBank PLC, 100 High Street, BRENTFORD

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TW8 8AY, England. Our account number is4285 0134.

DELIVERYAlthough every effort will be made to dispatchyourorder within 2-3 weeks from receipt of yourinstructions, we can not guarantee this time scalefor all orders.

RETURNSFaulty goods or goods sent in error may be re-turned for replacement or correction, but notbefore obtaining our consent. All goods re-turned should he packed securely in a paddedhag or box, enclosing a covering letter statingthe dispatch note number. If the goods are re-turned because of a mistake on our part, wewill refund the return postage. Goods returnedfor refund must be in resaleable condition andwill be subject to a 10% handling charge witha minimum charge of £2.50.

DAMAGED GOODSClaims for damaged goods must be received atour Dorchester office within 10 days (UK); 14days (Europe) or 21 days (all other countries)from the date on our "Recorded Delivery- slip.

CANCELLED ORDERSAll cancelled orders will be subject to a 10%handling charge with a minimum charge of£2.50.

PATENTSPatent protection may exist in respect of circuits.devices. components. and so on. described inour hooks or magazines. Elektor Electronics(Publishing) do not accept responsibility or li-

ability for failing to identify such patent orother protection.

COPYRIGHTAll drawings. photographs, articles. printed -cir-cuit boards. EPROMS, and cassettes published inour books or magazines (other than in third -partyadvertisements) are copyright and may not hereproduced or transmitted in any form or byany means, including photocopying and record-ing, in whole or in part, without the prior per-mission of Elektor Electronics (Publishing) inwriting. Such written permission must also heobtained before any part of these publicationsis stored in a retrieval system of any nature.

Nothwithstanding the above. printed -circuitboards may be produced for private and personaluse without prior permission.

LIMITATION OF LIABILITYElektor Electronics (Publishing) shall not beliable in contract. tort, or otherwise. for anyloss or damage suffered by the purchaser what-soever or howsoever arising out of. or in con-nexion with, the supply of goods or services byElektor Electronics (Publishing) other than tosupply goods as described or. at the option ofElektor Electronics (Publishing). to refund thepurchaser any money paid in respect of thegoods.

LAWAny question relating to the supply of goodsand services by Elektor Electronics ( Publishing)shall be determined in all respects by the lawsof England.

May /994

Annual subscription rates (1994/95)

United Kingdom £2800Rest of the world (surface mail) 34.00AIRMAILEurope & Eire £35.00USA & Canada $59.00Middle East & North Africa 44.00Central & southern Africa £44.00Central & South America £4400Australia & New Zealand £4600Far East & South Pacific regions 46.00

Payment may he made by cheque in sterling drawnon a London clearing bank (but see below), postalorder, VISA, ACCESS, MASTERCARD or EuRocARD (in whichcase the subscription must be sent to the cardholder's ad-dress) or by direct transfer to our Giro Account no. 34152 3801. Do not send cash through the mail. Chequesand postal orders should be made payable to ÈlektorElectronics Publishing'. Giro transfers should be made bycompleting and sending the appropriate transfer/depositform to the National Giro Centre (UK) or to your nationalGiro Centre.

If you live outside the United Kingdom, payment mayalso be made by Bankers' sterling draft drawn on a Londonclearing bank or Eurocheque. Eurocheques should bemade out in pounds sterling and have the holder's guar-antee card number written on the back.

US dollar cheques. Subscribers in the USA and Canadaonly may pay in SUS cheques.

The standard subscription order period is twelve months.If a permanent change of address during your subscrip-tion period means that copies have to be dispatched by amore expensive service, no extra charge will be made.Similarly, no refund will be made, nor expiry date extended,if a change of address allows the use of a cheaper service.

Student applications, which qualify for a 10% (ten percent) reduction in current rates, must be supported by ev-idence of studentship signed by the head of the college,school or university faculty.

Please note that new subscriptions take about four weeksfrom receipt of order to become effective.

Cancelled subscriptions will be subject to a charge of25% (twenty-five per cent) of the full subscription price or£7.50, whichever is the higher, plus the cost of any issuesalready dispatched. Subscriptions cannot be cancelled afterthey have run for six months or more.

Our bankers are National Westminster Bank PLC, SortingCode 60-03-23, 100 High Street, Brentford TW8 8AY,England. Our account number is 4285 0134.

September 1994

L


SWITCHBOARDSwttchboard allows all PRIVATE READERS ofElektor Electronics one FREE advertisementof up to 108 characters, including spaces,commas. numerals, etc., per month.

Write the advertisement, which MUSTrelate to electronics, in the coupon on thispage; it MUST INCLUDE a private telephonenumber or name and address; post officeboxes are NOT acceptable.

Elektor Electronics (Publishing) can not ac-cept responsibility for any correspondence ortransaction as a result of a free advertisementor of any inaccuracy in the text of such an ad-vertisement.

Advertisements will be placed in the orderin which they are received.

Elektor Electronics (Publishing) reservethe right to refuse advertisements withoutgiving reasons or without returning them.

WANTED. Microwave gear - anything con-sidered: equipment, books, etc. Phone Robinon 01268 524 968

FOR SALE. Sony SLC 300E Tamax videorecorder plus 30 tapes. Also stereo cassettetape deck Sony TC229SD. £40 each. Phone01474 334 997.

WANTED. One or 2 Sage Supermos 2. Fax+65 4804 535 or write to Werner, 26 Ang MoKio Ind. Park 2, Singapore 2056

WANTED. Data and projects on MFS time trans -

IFAN ADVERT

IS WRONG,WHO PUTSIT RIGHT?

tie do,

The. Advertising StandardsAuthority ensures advertise-ments meet with the strict.Code of Advertising Practice.

So If you question anadvertiser. they have toanswer to us.

lb find out more about theASA. please write toAdvertising Standards Authority.Dept X. Brook Must,

lbrrington Place,London WCIE 711N.

ASAihis space is donated in the interestsor high standards in advertisements

mission from Rugby. Please write to K. Uscroft,87 Cliff Road, Hornsea HU18 1 HU.

FOR SALE. Amiga to TV monitor lead, SCARTinput. Send £10 to David Price, 6 March BankGrove, Balerno, Edinburgh EH14 7ES.

FOR SALE. Complete set of Elektor Electronics,No. 1 to No. 196. excellent condition with 15binders. Best offer. Contact Rob on 01222372 495.

WANTED. By long term U B40 a cheap copyof 301 Circuits or 302 Circuits. Please phoneHull (01482) 589 849.

HELP! I need to contact someone who builtthe GALprogrammer. Please write to GabrielCaffese, 36 N° 536, La Plata CP1900, Argentina.

FOR SALE. Rotary converter A.M. TypeRC8A, 24 V d.c. input, 115 V a.c. (400 Hz)output at 1.8 A. £40 plus carriage. Phone(0590) 676 708.

WANTED. Formant Synthesizer: modules, lit-erature, diagrams, etc. Also ETI/Digisoundand similar. Phone Brian on (0268) 559284.

FOR SALE. Tektronix 453 oscilloscope.£150 ono. Please ring 021 422 1999.

FOR SALE. Telequipment S51E oscillo-scope £50 (negotiable). Phone Tris on (0954)780 962 evenings.

FREE ACCESS. MCS51 microfiles and mes-sage area on the shed B&S; 1200-14400bps, 24 hours. Phone +44 (0)223 563 468.

Send this coupon toElektor Electronics (Publishing)

P.O. Box 1414Dorchester DT2 81(H

England

B ock capitals please - one character to each box

ELEKTOR ELECTRONICS 10/94

Name and address MUST be given

WANTED. Circuit or Dip Sw details for mon-itors NEC Mod 1110768 and 1TOH Cit220.Phone Mike on (0736) 65664 - will pay costs.

FOR SALE. 20 MHz oscilloscope, excellentcondition, £120. Also brand new VGA moni-tor £80. Phone (0302) 341 098.

Books from Elektor Electronics (Publishing)

The following books are currently available:301 Circuits £9.95 $14.50302 Circuits £9.95 $14.50303 Circuits £10.95 $17.90304 Circuits £12.95 $23.95305 Circuits (published in May 1994) £14.95 $27.70SMT Projects £ 9.95 $14.50Microprocessor Data Book £10.95 $19.90Data Sheet Book 2 £9.95 $18.50Data Book 3: Peripheral Chips £10.95 S19.95Data Book 4: Peripheral Chips £10-95 $19.95Data Book 5: Application Notes £10.95 $19.95

How to order:UK and Overseas private customers (NOTin USA and Canada) from:Elektor Electronics (Publishing)PO Box 1414 Dorchester, England DT2 8YHTelephone (0305) 250 995Fax: (0305) 250 996

UK and Overseas bookshops, schools,colleges, universities and bulk orders(NOT in USA and Canada) from:

Gazelle Book Services LtdFalcon House, Queen Square, Lancaster,England LA I 1RNTelephone (0524) 68765Fax: (0524) 63232

USA and Canada ONLY from:Old Colony Sound - please see order formon page 79 for details


74

ELEKTOR ELECTRONICS is available from, among others:CRICKLEWOOD

ELECTRONICS LIMITED40 Cricklewood Broadway,

London NW2 3ETTelephone 081 450 0995

Fax 081 208 1441

L.F. HANNEYYour electronic componentspecialist for Avon, Wilts &

Somerset.77 Lower Bristol Road, Bath,

Avon, Telephone 0225424811

AAGE NIELSEN1 Sortedam DosseringenDK-2200 Copenhagen,

Denmark,Telephone 01 39 30 10

Fax 031 39 05 02

TABACCARIA BRITANICAPraga do Duque da

Terceira 191107 Lisboa, PortugalTelephone 932 4752

MK KNJIGARNASlovenska 29

LjubljanaSlovenia

Telephone 061 150 196

THE ELECTRONIC SHOPElectronic components, test

equipment, telephoneaccessories, computer

accessories, microphones,disco lighting, speakers, turntables, mixers, meters, stylus.

29 Hanging Ditch,Manchester M4 3ES,

Telephone 061 834 1185

HELMHOLT ELEKTRONIKFarvevej 2

DK-7600 Struer, DenmarkTelephone 97 85 26 11

D.P. HOBBS (NORWICH)LTD

Electronic componentspecialists. Amateur radio

equipment.13 St. Benedict Street,

Norwich NR2 4PE,Telephone 0603 615786

RCE ELECTRONICCENTRE

Boulevarden 34DK-9000 Aalborg, Denmark

Telephone 98 16 07 10

TECHNICAL BOOKS &MAGAZINES

289-299 Swanston StreetMelbourne, Australia 3000

Telephone 663 3951MANCOMP

240 Platt LaneManchester M14 7BS

EnglandTelephone 061 224 1888

GREENWELD27 Park Road

Southampton SO1 3TBEngland

Telephone (0703) 236 363Fax (0703) 236 307

VEJLE RC ELEKTRONIKSdr Brogade 42

P 0 Box 332DK-7100 Vejle, DenmarkTelephone 75 83 25 33

INEL Co.P.O. Box 1397

JL. Hariang Banga No. 3Bandung 40116

IndonesiaOMNI ELECTRONICSStock a wide range of

electronic components.174 Dalkeith Road,

Edinburgh EH16 5DX,Telephone 031 667 2611

BEBEK ELECTRONICSHirsimetsantie 26SF -15200 Lahti 11

FinlandTelephone (18) 33 99 46

Advertising Standards AuthorityAntex ElectronicsBadger BoardsB K ElectronicsBluebirdBull ElectricalCirkit DistributionCricklewood ElectronicsCrossware ProductsDisplay ElectronicsElectromailElektor ElectronicsESR Electronic ComponentsHart Electronic KitsHSP ElectronicsICE TechnologyInstrutekJPG ElectronicsLabcenterMaplin Electronic SuppliesMailtech Electronic ComponentsMicroAmpsNumber One Systems LtdPico Technology LtdPOWERwareQuantek ElectronicsRobinson MarshallSherwood Data Systems

INDEX OF ADVERTISERS

64,736121

964666163216237

38, 72, 73156821

Inside back cover41, 69

6325

Back cover8

614

674963

Inside front cover21

Smart CommunicationsSpeaker BuilderStewart of ReadingSuma DesignsThose EngineersTsien (UK) LtdUltimate TechnologyViewcom Electronics

40646365415539

16, 17

ADVERTISING SPACEfor the November 1994 issue may be reserved

not later than15 September 1994 by

Elektor Electronics (Publishing)Advertisement Office3 Crescent Terrace

Cheltenham GL50 3PEEngland

Telephone (01242) 510 760; Fax (01242) 226 626

to whom all correspondence, copy instructions andartwork should be addressed.

THEME OF THE MONTH in the November issue will bePRINTED CIRCUIT BOARDS


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III 1000E Version has ROM/RAMemulator built in: 128k(1 Mbit) standard, tiSoptional 512K (4Mbit) 01#

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WHY BUY AN INFERIOR IMPORTED PROGRAMMER WHEN YOU CAN HAVE A MANUFACTURERAPPROVED UNIVERSAL PROGRAMMER/EMULATOR DIRECT FROM ICE TECHNOLOGY!

We offer the best range of low-cost programmers available, now including our uniqueUNIVERSAL PROGRAMMERS WITH BUILT IN EMULATORS

E Unrivalled device support, for example the Micromaster 1000 programmes PICS, Z86, 87C705, 68HC705,TMS370, 77C82 ETC WITHOUT ADAPTORS, as well as the full range of Eproms, PLDs etc supported byall our universal programmers.

7 Approved by National Semiconductor for their full range of PALs, GALs, and MAPLs - other programmersclaiming approval are often only approved for EPROMs - a much less exacting specification!

All our programmers and programme/emulators work off the standard parallel port with any IBMcompatible PC, even laptops

7 Unbeaten programming times: Programme a 27256 in just 5 SECONDS including download and verify.Easy upgrade path between Models. 0 Y

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