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Heavy Duty 5A Drill Speed Controller DYNAMIC _ w...A/- MAGAZINE~ SERVICING -VINTAGE RADIO - COMPUTERS -AMATEUR RADIO - PROJECTS TO BUILD SCOPEMETER The next generation of hand-held instruments e PHILIPS FLUKE® Its a 50MHz bandwidth Digital Storage Scope plus ... Full 3000 count DMM e 25MS/s dual channel digital storage • 8-bit, 25 levels/divvertical resolution • 7ns rise time, 40ns glitch capture e 10ns/div to 5s/div timebase • Stores 8 waveforms (95 & 97) and 10 set-ups (97) • Measuring cursors (95 & 97) • "Auto-Set" automatic set-up of parameters, e.g. volts/div, time per div and triggering for any input signal • Functions include Min/Max recording, Touch Hold™. Relative and Percentage values, Autoranging etc e dBm, dBV and dBW (95 & 97) Simultaneous display of waveform and DMM functions ... • 5 Soft Keys for commands via pop-up menus • 12cm, 240x240pixel Super Twisted Nematic LCD screen • Fast reaction microprocessor control with extensive use of ASICs for low power consumption and high bandwidth • Floating high voltage measurements up to 600Vrms • Optical RS-232 Port for waveform plots, modem connection, set-up data, on-screen waveform comparison, field diagnostics and recalibration (97) • Low Power - 5W(typ) from NiCads, alkalines or car battery etc (4 hr internal battery) • Built-In component and baud rate testers and a sine, square and ramp signal generator (97) • Measures 47xl30x260mm, weighs 1.5kg Model 95 Adds measuring cursors and recording function Model 97 Adds waveform and set-up memories , back-lit LCD, generator functions, RS-232 interface We also stock the full range of Fluke Multimeters. Call us for the best prices on all Fluke Instruments. As one of Australia's largest distributors of Fluke, we wont be beaten on price. FREE 20-page Shortform Catalogue available. Ask about our Account facilities and special arrangements for Education and Government Departments. Express delivery throughout Australia and South Pacific Detailed brochures and specifications available. We arefactory trained to advise on your requirements for general purpose Test & Measuring Instruments ©IIDTI.£1r JP1rW IL1f J]) READER INFO NO. 35 129 Queen Street, Beaconsfield P.O.Box 37 Beaconsfield NSW 2014 Tel: (02) 698 4776 Telex: AA71958 Fax: (02) 699 9170 OLD : Electro TechnlCal Systems Old, Tel (07) 356 2699, Fax (07) 356 0456 w a lcom a h a r a Vol.5, No.9. September 1992 FEATURES THIS NEW SPEED controller can be used with power tools rated up to 5 amps. You can use it to control the speed of circular saws, electric drills, lawn edgers & other appliances. See page 28. 16 A Tutorial On PC-Based Data Acquisition by David Potter Transducers, signal conditioning & software 89 The Story Of Electrical Energy, Pt.20 by Bryan Maher Sydney's tramways & the Ultimo power station PROJECTS TO BUILD 6 Track Tester For Model Railroads by Leo Simpson & John Clarke Locate trouble spots quickly with this ingenious tester 28 Heavy-Duty SA Drill Speed Controller by Leo Simpson Use it with circular saws, drills & lawn edgers 46 The lnterphone Digital Telephone Exchange, Pt.2 by Jeff Monegal Assembly details & installation procedure 56 A Multi-Sector Home Burglar Alarm by Mike Zenere Easy to build circuit has digital keypads & microprocessor control LOOKING FOR AN UP-TO-DATE home burglar alarm that's big on features but low in price? This unit comes with optional remote keypads & has microprocessor control. Turn to page 56. 78 A General-Purpose 3½-Digit Panel Meter by Darren Yates Has switchable decimal points & can read voltage or current SPECIAL COLUMNS 37 Computer Bits by Mike Zenere A look at the 68705 microcontroller 40 Vintage Radio by John Hill Repairing an old Heathkit RF generator 64 Serviceman's Log by the TV Serviceman Death rattles: a thorny problem WHAT WOULD cause death rattles from an English Thorn TV set? The Serviceman solved the mystery. Details page 64. 86 Amateur Radio by Garry Cratt Build this relative field strength meter 93 Remote Control by Bob Young Internal combustion motors for R/C models, Pt.2 DEPARTMENTS 2 Publisher's Letter 4 Mailbag 8 Circuit Notebook 73 Product Showcase 96 Back Issues 98 Ask Silicon Chip 100 Notes and Errata 101 Order Form 102 Market Centre 104 Advertising Index BUILD THIS 3½-DIGIT LCD panel meter into your next power supply project. It features switchable decimal points & can read voltages up to 200V or currents up to 2A. See page 78 SEPTEMBER1992 1 Publisher & Editor-in-Chief Leo Simpson , B.Bus. Editor Greg Swain , B.Sc.(Hons.) PUBLISHER'S LE'I*I'ER Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Sharon Macdonald Sales & Marketing Mgr. Sharon Lightner Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman John Hill Jim Lawler, MTETIA Bryan Maher, M.E. , B.Sc. Jim Yalden , VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Magazine Printers Pty Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents . SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such . equipment. Editorial & advertising offices: Unit 1a/77-79 Bassett Street, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 2 SILICON CHIP Low voltage lighting is not low wattage It is interesting to see the trends in lighting in new houses these days. On the one hand there is a move to energy saving fluorescent lamps; not the strip lamp style which is well and truly out of favour with interior designers but the new compact types which plug into the standard bayonet lamp fitting. These are certainly more efficient than conventional incandescent lamps but are a great deal more expensive than standard fluorescent tubes. On the other hand , there is the trend to low voltage halogen spot lights. The small halogen lamp reflectors which are recessed into a cBiling are almost invisible when not turned on and they provide a brilliant white light which is great for highlighting decorative items such as glassware or sculpture. As far as interior decorators and architects are concerned, these lamps are definitely "in". The problem with these lamps is that the general public think that because they are low voltage, they must be low wattage and therefore don't cost much to run. And so it is not unusual to walk into a modern show home and find a dozen or more of these jewel-like spot lamps used in one room. They are not being used as highlights but for general illumination. Hence, you might find a "designer" kitchen with all the lighting provided by these spotlights. The general effect is one of gloom pierced by a few brightly lit areas. Typically, these lamps run at 12V and consume 50 watts each. So you can have a kitchen or family room with 500 watts or more of lighting and still not have a brightly lit room. When you consider that each of these expensive fittings is also backed by a transformer, then the actual power input is even higher. Another thing to consider is that because they are halogen lamps , those tiny bulbs become intensely hot; that is why they are intensely bright. I;3ut that intense heat also rapidly discolours their tiny reflectors and so the brightness drops off rapidly - while you continue to pay for all that power. Even sillier, some people want their low voltage lighting to be dimmable. Ordinary incandescent lamps can be dimmed but attempting to dim halogen lamps makes them very inefficient indeed. The whole point of this is that if you like the look of low voltage halogen spot lights in your home, then go ahead and install them. But realise that they are not effective for general lighting and they are not efficient - you will pay much more than if you had used fluorescents. Leo Simpson :-·-:-:-:-.•.·.· (tj CDM-2000 Microphone ;i~~;;::n~o;r:~ez:1::/::~~k (§ r 6 ~~~~i~iu gdB5:t:~~'smm i! 111 Only $89.9-. 5- ACCESS FAX ·••··•·( lj•·•• M~:~::~:l ~ BLUE Led"s ■ ■ I• • :o~i~;:1~~~~ zii~t::t:iti:1a':ot: ·>~o · · ~ ~ rf!:gr~i~n~~kHz. J;I 0 Diskettes Buy in Bulk and Save I 5.25" D.S.D.D. $38.00 per 100 ■ 5.25" D.S.H.D. $68.00 per 100 il~_gasi~~-100 PF-2650 That's Right I BLUE LED's I L uminous In tensity o 20mA: 7mcd (min.). 14mcd (typ.) ■ Forward Voltage: 2.7V (min.). 3.0V (typ.), 3.5V ~ m o 20mA. a x . ) ■ Reverse Voltage: 5.0V. Full Viewi ng Angle: 30 deg. _ , th 0 : :vaa~~a;l~nFn ;,,;; :n~ 5mm case. ~■ Case Colour : water-clear. ■ 3mm Part No.: L-934BC (BLUE) 1 to 9: $3.95ea. 10+ $3.55ea. 50+ $3.20ea. 100+ $3.00ea . 5mm Part No.: L-53BC (BLUE) 1 to 9: $3.95ea. 10+ $3.55ea. 50+ $3.20ea. 100+ $3.00ea . VOCA Cordless Telephones CT 7800 fax machine for under $700.00 e<:~t~~~:r:~~i~O~~:~~~i:~e~~~es 20 memories Full 2 way intercom a- 250 mtr. range. a-Tone/Pu lse dial. a- Automatic on/off. a- PI us more ! 9' Q' I ~~ii:ri<at>z~;~: i~: es Now $329.00 CT 3800 ..- 10 memories a- 2 way paging .,.. 250 mtr. range. ...-Tone / Pulse dial. a- Easy-Call Com pat. a- PI us more ! w 30 mtr. Paper Roll ..- Austel Permit No. A92/25D/0144 - 12 months Warranty ~~~~~~. watto~t~V Now $229.00 DC to 240V AC INVERTER 300 Over c urrent circuit breaker. Fused 240 V output. ■ Built in panel meter. ■ Strong steel case & chass is. ■ Full y built (not a kit). ■ Great to power lights, fridge, TV, etc. ■ ■ ------- The first Fully- Automatic and Transparent Fax-Modem Switch The VSI "FMX" Fax - Modem S witc h a- Shares Fax & Modem on same line ._. Effortless hands-off operation o- Automatically sends cal ls to modem or fax a- Requires NO action by sender or receiver r"':i:: ,wt .<.tCDEN. i"O'OIVI: ,"j!'.' e' ; ~ Use with all Hayes-compatible modems and any modem on which Carrier Detect Time and Number of Rings arc adjustaMc. Automatically routes incoming data calls to tax or modem. The VSI "FMX " is not to be confused with otha fax switch systems. Only $399.00 Austel Permit No. A90/148/0342 LAB 4 4 in 1 Work Station The LAB 4 has four full function lest instruments ■ ~ David Reid 127 York St, SYDNEY 2000 Ph: (02) 267 1385 ~ Electronics P.O. Box Q103,SYDNEY 2000 Fax: (02) 261 8905 A.C.N. 001-372 -372 a DC POWER SUPPLY Triple Output; 5V. 15V. 0-50V -l'!JmT/lfflil!li!!ii f SJii Postal Charges $5 · $25 ......... $4.00 $26 · $50 ...... $6.00 $51 · $100 ..... $7.00 $101 · $499 .. $9.00 $500 • .. ... .... . $ 15.00 MAILBAG Feedback on the infrared railroad controller I am writing to you with regards to the Infrared Railroad Controller described in the recent April, May and June issues of SILICON CHIP. I only copied the infrared part of the circuit to make a 10-channel remote control for my stereo system. I had great difficulty getting the receiver part going. It would work fine for a while and then go into oscillation. The problem was that pin 9 on the MV601 receiver was not connected to ground. Pin 9 is not connected on your circuit diagram. I believe that this pin is output enable and must be taken low for operation. Anyway, I believe that SILICON CHIP is a great magazine and I am going to subscribe. It's good to see that you are including artwork with all your projects. Keep up the good work. P. Morphett, St Marys, NSW. Comment: while pin 9 of the MV601 is not shown connected on the circuit diagram (it should have been}, it is connected on the PC board so this fault will not occur on commercial boards or boards included in kits. Control via PC printer port I would like to reply to A. L. 's query in "Ask Silicon Chip" June 1992, regarding control of external devices via the parallel printer port. Both GW BASIC and QuickBASIC have the "OUT" command which can directly control the eight data lines of a Centronics parallel port. These data lines (pins 2-9) can be set to either 0V or +5V relative to the commoned earth lines on pins 18-25. It is necessary to know the address of the port which is to be used. This is usually decimal 888 for the IBM PC and compatibles. The command has the form OUT (address),(number). The number selected controls the switching of the data lines in the following way. Consider the eight data lines as binary digits which can be either zero (0V) or one (+5V). Entering the command switches the data lines to repre4 SILICON CHIP sent the binary equivalent of the number you have selected. For example, entering OUT 888,96 sets the lines to 01100000, which is 96 in binary notation. The lines remain latched in this condition until receipt of a new command. By selecting the appropriate numbers, you can individually control the switching of each line, either directly or from within a program. Only minimum current should be drawn from the data lines, so buffering is advisable and isolation an advantage. Prior use or the boot sequence may have left some ofthe lines switched on so before activating the device you wish to control, it is prudent to issue the command OUT 888,0 to ensure that they are all switched off. By this means, a computer can control eight relays. I hope this information proves as useful to others as it has been to me. D. MacMillan, Yorkeys Knob, Qld. Quiet appliances are available Your comments regarding noisy appliances in the Publisher's Letter, July 1992, are quite correct. The consumers are at fault because they want the best for the cheapest price which simply results in noisy appliances. However, as I am in the whitegoods industry, I can safely inform you there are quiet appliances out there but you do have to ask for a demonstration, otherwise you find out the hard way. Washing machines are actually getting quieter as some manufacturers choose not to have a gearbox but rather a direct drive system. Hitachi is the pioneer of this design. J. Coppola, East Geelong, Vic. Wanted - a pipe dream Wanted: one pipe dream - a double general purpose outlet with "extra" space between the outlets so that my plug-in trannies will fit , without fouling the other outlet. Or a 4-way extension board without the poxy "classic" SILICON CHIP, PO Box 139, Collaroy Beach 2097. standard width between outlets! Must be for general sale to the public at their favourite electrical retailer soon! P. Truscott, Tullah, Tasmania. What happened to the microprocessor kit? Several months ago, I wrote to SILICON CHIP expressing a keen interest (along with my colleagues) in the publication of a microprocessor kit. Since then I seem to have sparked interest in the microprocessor debate. My initial request was to publish a simple processor development kit that beginners and intermediate constructors could build. Cost and availability of programming appropriate EPROMS would be a major factor in a kit such as this. I believe that microcontrollers such as the 8051 and 68075P3 are powerful devices but difficult for the average hobbyist to program. Magazines have used microcontrollers in the past. You buy a preprogrammed microchip and just plug it in, leaving no room for experimentation or development. A well-documented processor such as the Z80 would go a long way to unravelling the mysteries of microprocessor design. We have seen that your readers have responded with interest to this subject. Is SILICON CHIP any closer to publishing a microprocessor kit? J. Goldburg, DSE, Richmond, Vic. You certainly have triggered a lot of interest and we now have a number of people offering designs. Both the ZBO and 8051 and its many variants have merit. We have not decided on any design approach yet but we expect to publish. a number of designs within the next six months. Advice on the Studio 200 amplifier module We had an amplifier module in today and thought you might be interested in the fault. The module is from the February 1988 Studio 200 design. I have had some before with this • A.(J;\'#; problem - that is, when not using IRH brand emitter resistors, the unit oscillated when the polyswitch opened and soon after the output transistors failed. The cure was to add a second Zobel network before the polyswitch. I believe that the existing Zobel network should be before the polyswitch to maintain amplifier stability when the polyswitch opens. While this module is certainly not a n ew design, this information may come in handy in future. Steve Calder, Hycal Electronics, Parramatta, NSW. The real fix for the Akai VS-112 drum motor Thank you for an interesting and informative Serviceman column; I look forward to reading it every month. I write to you with reference to your July column, in which you describe problems experienced with an Akai VS-112 drum motor. I have had some experience with this model and indeed this particular fault. The "bloke" was on the right track in fitting a heatsink to the TA7245 IC but probably not likely to be successful. Overheating of this component is a known problem and is the cause of the symptoms described in your article. Another common symptom is the motor stopping after playing a while. The correct fix is replacement of the PCB motor assembly (part number BM-M3223A020A). The replacement from Akai is a modifi ed typ e which now does have a heatsink fitted to the TA7245 IC. It is also stocked by WES Components in Ashfield (part number VM3223). The price is $79 (including. tax). B. Ronning, Calwell, ACT. Articles on computers I would like to take to task your correspondent, Bill Smith, for his letter in the July issue of SILICON CHIP. While Bill may not be interested in computers , either as a user or programmer, or interested in what's inside these mighty boxes of tricks , they are an integral part of modern electronics. I am not a Ham myself but I have friends in the Bundaberg area. where packet radio is a thriving part of the hobby. The computer is , of course, an integral part of this mode of radio transmission, in this case mainly Commodore 64s and Amigas. The computer is, when stripped of its fancy case, a good example of the application of digital electronics. I agree that the jargon is a bit off-putting but to the hobbyist, who likes to get stuck in and update the memory or add extra features , this is a fascinating part of computer technology. I am sure that there are many readers who would welcome articles and projects and maybe even the terminology could be clarified in the process. Whatever opinions may be; computers and digital electronics are here to stay, so go to it. J. Luxton, Biggenden, Qld. Microprocessor development kits I would like to disagree with some of the opinions expressed by S. Finneran on the subject of microprocessor development kits in the July issue of SILICON CHIP. Careful reading of my May letter will show that I did not rule out the possible use of a controller like the 8051 while pointing to general considerations in the choice of chip. Certainly an 8051/xx kit could satisfy a lot of potential users and may well be the best compromise among the various possibilities. But not for me. BASIC has no attraction for my applications; being slow, divorced from interrupts and memoryconsumptive. I'm not sure, but I suspect that 8051 program development (particularly in machine language) may be difficult unless one has access to an IBM clone and a (high-priced?) Assembler program. After all, there is more to the cost side than just the kit unless one is fortunately placed. Mr Finneran erred in saying that I have a problem choosing a chip set, since I bought a stock of 6502s when they were $2 each; and they are easily programmed on my Commodore 128. I was merely trying to open out the discussion before it got pointed in any particular direction. G. Wormald, Florey, ACT. !I Super ' Savings on \ fl,f• these br~nd ••" new prime grade components SOLDER HEATSHRINK TUBING Big savings on quality 60/40 Tin/Lead, resin-cored solder. Perteet for electronics. Long lasting ½ kilogram rolls. Diameter: 056mm was $23.50 NOW $14.50 0.71mm was $22.88 NOW $13.50 1.0mm was $21.00 NOW $11.50 1.6mm was $19.25 NOW $12.00 Upon application of heat, this tubing shrinks to approximately half normal size · and our prices have shrunk to approximately half normal si4e!! Per metre: 1.6mm was $1.95 NOW $1.20 2.5mm was $2.95 NOW $1 .50 3.5mm was $3.45 NOW $1.80 4.8mm was $3.65 NOW $1.90 SPEAKERS 6.4mm was $4.75 NOW $2.40 5" round 8 ohm tweeter (as used in 9.5mm was $5.25 NOW $2.70 some Pioneer systems) 12.7mm was $5.85 NOW $3.00 2 tor $7.00 5" round 4 ohm 2 watt general OR· try one of our handy packs ol purpose. Ideal for the test bench assorted sizes. Only $6.50. $3.00 SIEMENS MAINS FILTER MINI VICE Ever wanted a third hand whe11 so~ering connectors etc. . ? Try Thlsll Plastic bodied, suction mounted base, wide jawed, light· weight vice. Save time and improve solder joints. ONLY $8.95 Filter "noisy" and "dirty" mains power with this high quality self contained uni t. 115/250VAC, 41\ 50/60H, . Simply add vanstor (V275LA20 $1.50) for spike protection. Order quickly · only 30 left! ONLY $15.95 ASSORTED GOODIES D89 plugs (solder) D89 covers (plastic). . . 25KHz ultrasonic trans./rec. 1uf 50V RB electro cap. . were NOW .. $1.95 $ .50 . . ... $1.75 $1.00 . $11.95 $3.00pr. . . . $ .28 $ .1 Oor $3.50/50 .55 .20 .70 .30 .60 .10 .78 .20 .80 .15 .80 .15 .85 .25 .85 .25 .85 .25 .85 .25 .82 .20 220uF 25V RT electro. Cap.. . 220uF 35V electro. cap.. 10 Kohm 4W resistor.. 270 ohm SW resistor. . 2.2 Kohm 6W resistor . 33 Kohm 6W resistor. . 82 ohm 7w resistor . . 120 ohm 7W resistor. 560 olvn 7W resistor. 2.7 Kohm 7W resistor. 1·3.5 pF trimmer capacitor . . 1.4·5.5 pF trimmer capacitor . . .82 .20 2·27 pF trimmer capacitor . .82 .20 4·40 pF trimmer capacitor. .82 .20 5·60 pF trimmer capacitor. . .82 .20 5.5·6.5 pF trimmer capacitor . . . . . .82 .20 CM30!J2 35A 200V bridge rectifier . .. . 8 50 50 7815K (+)ve 15v T0-3 Vrntage Reg . · : . · : · 1:40 11:00 79 15K (·)ve 15v T0-3 Vrntage reg...... .. .. .. .40 1.00 1Ok LOG. 45mm travel slide slide pot. . . . 3.60 .50 1M linear VCU rotary pot.. . 1.85 .75 SOOK linear VCU rotary pot. . 1.85 .75 RElAY MADNESS!! Siemens V23030 A10 12 A104. Fla~ 4-change over. 4·12 VDC, 50ohm, 2,\ 250 VAC. Were $32.50 NOW ONLY $5.00 Siemens V21354 D0426 Fl 04. Cradle relay, 2 changeover 18-40 VDC, 2450 ohm, 10A 250 VAC. Were $17.60 NOW $4.00 Siemens V23027 80006 A101. PCB mount, single change over, 17-40 VDC, 1200 ohm, 8,\ 250 VAC Were $10.40 OW $4.DO Lynnks LD21 OH. DPDT, PCB mount, 12 VDC, 150ohm, 10,\ 250 VAC. As used in many kitsets Were $11.85 NOW $4.50 NEC MR71 C-12. SPOT, PCB mount, 12VDC, 285 ohm, 10,\ 250 VAC. As used in many kitsets. Were $8.00 NOW $3.00 SUPER CAP A huge 0.1 Farad (100,000 uF) CABLE TIES capacitor rated at 5.5vDC. . . Great for energy storage tor Pandu1t 94x2.4mm Cable lies. memories, etc. Black or white. $1.50 per 100 were $2.52 NOW 50C CATALOGUE APOLOGY Our sincere apologies to all our customers awaiting copies of our catalogue. We are having to endure a systems error at our typesetter. He 1s installing a new system and production should be finished shortly. MAJOR CREDIT CARDS/CHEQUES WELCOME Orders under $50 - $4.00 P&P - Orders over $50 - $6.00 P&P ALL ELECTRONIC COMPONENTS 118-122 Lonsdale Street, Melbourne Vic. 3000 Telephone: (03) 662 3506 Fax: (03) 663 3822 SEPTEMBER1992 5 Track tester for model railroad layouts Do you have trouble with open circuits or dirty spots on your model railroad layout? Do your locomotives stop or stumble as they move around? If you answered yes to either of these questions then you need our dandy little track tester for HO or larger scale layouts. The centre LED always lights provided there is voltage on the track. The other two LEDs only light up when an open circuit is detected and the LED which lights up shows which side of the track has the open circuit. Pretty neat, huh? But wait till you see how the circuit works and you will be even more enthused. Circuit operation By LEO SIMPSON & JOHN CLARKE If you h ave an operating layout, there is nothing more frustratingthan having your trains stop in inaccessible locations or jerk unrealistically as they move through points or across rail joins. The trouble is, it can be devilishly hard to locate some of the trouble spots, particularly on a large layout and where the lighting is poor. Unfortunately, the ever-handy multimeter is unable to pinpoint many track problems. That's because it is a high impedance device and is quite useless at picking up what might be quite small points of dirt _o r oxidation on the track. We've been thinking about this problem for some time now, since it is one that must trouble every railway modeller at some time or other. What was needed was some device that could be pushed around a layout by a locomotive and which would have LEDs to light up when trouble spots were detected. Ideally too, the device was to be powered from the track, regardless of polarity, so that it would not need a battery. The result of our cogitations and experiments is presented here. It consists of a small PC board which can be mounted on an open 4-wheel or bogie wagon. The PC board has three bicolour light emitting diodes (LEDs) . The PC board for the Track tester is mounted directly on a wagon & connections made to the wheels via current collector wires. 6 SILICON CHIP The circuit consists of three bi-colour (red/green) LEDs , four 68Q 5-watt wirewound resistors and three 560Q 0.5W resistors, and tha:t is all there is to it. Fig.1 shows how these components are connected together. Notice that we have marked four points on the circuit as A, B, C and D. Now consider that the circuit is connected to all four wheels of a 4-wheel wagon. Consider also that the wagon is on the track and 6V is applied to the track. Hence, LED 1 will be lit to indicate the presence of track voltage. Depending on the polarity . of the track voltage, LED 1 will glow red or green. If there are no open circuits between the wheels and rails, neither LED 2 nor LED 3 will light. LED 2 cannot light because there is no voltage between points A and B. Similarly, LED 3 cannot light because there is no voltage between points C and D. And of course, LED 1 does light because there is 6V between points B and D. Taking our analysis a little further, each of the resistors Rl, R2, R3 and R4 will have 6V across them and therefore will dissipate about 5 00mW each. That is. the normal condition. Now consider what happens if the wagon crosses a section of rail which is dirty or open circuit. Let's say for the moment that the wheel contact associated with point B suddenly loses voltage because of dirt on the rail. Current will now flow from point A via a 560Q resistor, LED 2 and paralleled resistors R3 & R4 to point C. Thus, LED 2 will light to indicate an LEO2 TRACK BREAK LEO1 TRACK VOLTAGE FRONT REAR LEO3 TRACK BREAK TRACK BREAK TESTER Fig.1: the Track Tester circuit uses three bi-colour LEDs & seven current-limiting resistors. Depending on the track condition, one of more of these LEDs will be biased on to indicate the exact nature of the problem, or to indicate that the track is OK. open circuit in the rail on that side. What if point B is OK but point A goes open circuit? Current now flows from point B via LED 2, the 5600 resistor and paralleled resistors R1 & R2 to point D. Thus, LED 2 again glows but in a different colour this time to indicate an open circuit in the section of rail associated with point A. Similarly, if point D goes open circuit, current flows from point A via paralleled resistors R1 & R2, LED 3 and its associated 5600 resistors to point C. Hence LED 3 glows to indicate an open circuit on that side of the track. We'll let you do the remaining case of what happens when point C goes open circuit. Again, LED 3 will glow but with a different colour because the current flows in the opposite direction. If the wagon comes to a dead section of track whereby points A and C (or points B and D) both go open circuit, both LED 2 and LED 3 will glow. There's another little wrinkle to this circuit and that is that LED 1 may or may not go out, depending on the direction in which the track tester wagon is being pushed. If it is being pushed forwards and points A or C go open circuit, LED 1 will remain alight while LED 2 or LED 3 glows. If it is being pushed backwards and .points B and D go open circuit, LED 1 will be extinguished and LED 2 or LED 3 glows. To sum up, the track tester will tell you which rail is open circuit each Fig.2: take care with the polarity of the LEDs when installing them on the PC board (the anode lead is the longer of the two). The four connections to the wagon wheels must be made using spring wire. Don't use tinned copper wire for this job, as it won't give reliable contacts. f? Ti!; fl ~~ time LED 2 or LED 3 lights. And if both LED 2 and LED 3 light up, then the wagon has come to a dead section of track. Unless your track is scrupulously clean, you can normally expect LED 2 and LED 3 to light spasmodically as the track tester wagon is pushed around the track. It will highlight any problem spots and will also light up LEDs 2 and 3 as it goes over the dead sections of points. Board assembly Assembling the PC board is pretty simple. Put the 5600 resistors in first, followed by the four 680 5W wirewound resistors. The wirewound resistors are stood "end on" to save board space. Strictly speaking, you can put the PARTS LIST 1 PC board, code SC09308921, 50 x 29mm 3 red/green LEDs (DSE Cat. Z4074 or equivalent) 4 68Q SW wirewound resistors 3 5600 0.5W resistors 1 4-wheel or bogie wagon with metal wheel sets. 4 brass or phosphor-bronze current collector wires Note: PC boards for this project will be available from RCS Radio Pty Ltd, 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491 . Fig.3: this is the full-size etching pattern for the PC board. bi-colour LEDs in either way around and they will still work. However, if you want them to light up in a consistent fashion, connect them in as shown on the board wiring diagram. As with conventional LEDs, one lead is a little longer than the other and this is designated the A lead (even though it is both anode and cathode of an internal LED) . Having installed all the components, you will then need to connect four brass or phoshor bronze current collectors which will lightly ride on top of each wheel of your wagon. When you fit the PC board to your wagon, you will need to adjust the collector lead tensions so that they make good contact while still allowing the wheels to rotate freely. For reliable operation you will need to use metal wheels, not plastic wheels which have been plated. You will also need to fit weights to the wagon so that the wheels make good electrical contact with the track. When you have finished the assembly, it is an easy matter to check it. Just apply power to the track and roll the wagon along it. The LEDs should then behave as described above. Note tnat while we built our prototype track tester onto a 4-wheel wagon there is no reason why it could not be built onto a bogie wagon. Again, it should be fitted with metal wheelsets and the collectors will need to be fitted onto the bogies and connected to the PC board via very light and flexible leads. SC SEPTEMBER1992 7 Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. +9-12V 47k 22k 47k 22k 22k 47k 7 ICl 555 IC2 555 LEDl RED Traffic lights for model train layouts The concept for this circuit was originally published in March 1992 but, not to put too fine a point on it, that circuit had bugs. In response to a reader's pleas, we subsequently debugged it by breadboarding the circuit in our workshop. The circuit consists of three inter- Automatic electric blanket controller How many of us go to the trouble, or even remember, to turn off the electric blanket during the day? Chances are they're left on continuously, especially if we have children. At about 70W per blanket, that's quite a lot of wasted power. This unit will automatically turn your blanket off during daylight hours and then turn it on again at dusk. It uses just a few inexpensive components, so you can afford to fit one to every blanket in the house. The power thus saved will quickly recoup the modest outlay. A light dependent resistor (LDRl) is used to monitor the ambient light level. At dawn, its resistance drops, turning on Ql and shunting the LED of the opto-coupled Triac driver. This turns the Triac off, thus effectively disconnecting the electric blanket from the mains. 8 SILICON CHIP IC3 555 + + .,. 0.1 VR3 2M 0.1 22! LED3 GREEN .,. 22! 0.1 locking 555 timer stages which are wired as monostables. These drive red, orange and green LEDs and each stage has its own time delay, as set by trimpots VRl, VRZ & VR3. VRZ is set so that the orange LED only comes on for a short time. Each 555 stage lights its respective LED in sequence. Assume initially that pin 3 of ICl is high and that the red LED is on. When pin 3 goes low at the end of the timing period, it momentarily pulls pin 2 of IC3 low via a 0. lµF capacitor. This triggers IC3 which now turns the green LED on. When IC3 times out, it triggers ICZ in similar fashion. ICZ in turn triggers ICl at the end of its timing period and so the cycle is repeated indefinitely while ever power is applied. Darren Yates, SILICON CHIP. A i - - . - -.......- - - - - - - - - - - - - - - - - - - . - - - - - , D2 1N4004 24 VAC l TRIAC1 SC141 A2 01 1N4004 N_...,____.___~ Power for the circuit is derived from the mains via a O.ZZµF capacitor. This is rectified, filtered and regulated to about 8V using zener diode ZD1. As an option, a miniature neon indicator could be wired across the load terminals to verify operation. Apart from that, the only critical component is the O.ZZµF 250VAC capacitor, which must be mains rated. A word of warning: the entire unit is at mains potential so exercise due care when handling and testing it. Any small case can be used to house the device and this should be fitted with.a flush-mounting mains socket. If for any reason, such as sickness, you need to have warmth during the day, simply drape a cloth over the unit so that the LDR is covered. R. Rochfort, MacLean, NSW. ($20) r--....--....-------<,---.-------<,--+-....------.-------,9----..,_--t-----+5V 33 10k 1 J R Ot-3......---t--..:ii 12 F--+.-:.::iCK , IC2a 4K 27k -:- 10VWI 10 14 R 73LS107 l3 LEO DISPLAY + GATE LEDO ANO 0 0 LED2 LED3 :=0-ouTPUT IC3 74LS155 13 TO INPUT A o - - - - - - - - - - t ---i A OR PINS OF GATE UNOER TEST B o - - - - - - - - - :=D--ouTPUT :=, I LE03 ◊ LED2 LED3 ◊ LEDO :=Q>-ouTPUl Because IC2b divides the Q output ofIC2a by two, the inputs to the logic gate under test toggle through all four possible logic combinations (ie, 00, 01, 10, & 11). The logic gate itself drives transistor Q1 via D1 and a lOkQ resistor. This transistor inverts the output from the gate and toggles the STROBE & DATA inputs (pins 14 & 15) of IC3 high or low. IC3 decodes the signals on its A and B select lines and on the STROBE and DATA lines and switches on one or more LEDs to indicate the type of gate under test. For example, if an AND gate is connected to the circuit, the LED 3 comes on. If the device is an XOR gate , then LEDs 1, 2 & 3 are lit. Switch S1 turns on all the LEDs and LED1 D-ouTPUT NANO This mixer circuit was developed to provide a high dynamic range front end for a HF receiver. It has a gain of approx +6dB , a discernible signal sensitivity of 0. lµV, and a dynamic range of 94dB. The balancing pot (VR1) between the sources of the two FETs is used to null out the local oscillator signal 1n the output. Its setting has virtually no effect on the dynamic range. The two inputs both present a load of 50 ohms, while the output impedance can be scaled to any likely impedance by adjusting the turns ratio in the output transformer (50 ohms in the example shown). A disadvantage in some cases is ◊ LE02 0 01 Cross-coupled FETmixer LED1 0 EXOR PN100 This simple circuit can be used to test 2-input logic gates, including CMOS and TTL types. It uses four LEDs to indicate the type of gate under test - ie, AND, NAND, OR, NOR, XOR and X-NOR. IC1 is a 555 timer and this clocks JK flipflop IC2a which thus divides by two at its Q output. IC2a in turn drives one input of the logic gate under test and the A select input of IC3 (a 74LS155 2-line to 4-line decoder). It also clocks IC2b which further divides by 2. IC2b in turn drives the other input of the logic gate under test. and the B select input of IC3 . ◊ LEDO LEDO 5.6k Tester for 2-input logic gates 0 ◊ ◊ 1k +5V---------''NI,~- S1 ON LED1 LED2 LEDO ◊ ~=D-ouTPUl :=)Dr-ouTPUT LED3 0 LED1 0 LED2 LED3 0 0 LEDO LED1 ◊ EXNOR LED1 ~ ◊ ◊ NOR 0 LED2 0 0 LED3 ◊ is used to confirm that the LEDs are all OK. The jumper link is installed when testing gates that have open collector outputs (eg, 74LS09). Sheldon Munoz, Lidcombe, NSW. ($20) 1011 that the circuit configurar----....----¥N~--+12-15V tion is an efficient doubler of the input signals. If these _ VC1 frequency "spurs" are well . 6-60pF removed from the IF, then a simple tuned circuit will provide sufficient filtering . LOCAL OSCILLATOR The dynamic range of the RF iN G IN mixer is dependent on both 0----11------+the supply voltage and the local oscillator level. Higher supply voltages increase L1 301 ENCU ON 150-2 TOROID both the dynamic range and L2 : 31 the conversion gain. The optimum local oscillator level is approximately +10dBm. The circuit was tested with input signals from 1-Z0MHz supply voltage and the local oscillator drive level. to produce an IF of 9MHz. The current consumption is approxiJ. Rickard, mately 15-25mA, depending on the Heathmont, Vic. o,I SEPTEMBER1992 9 INSITE 1325VM 20MB FLOPTICAL DRIVE ~ Atlaatafloppydrivethatlatrulymulti-purpose. 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Spees: CTR: 14" 90° delection, dark tint, non glare. Display Size: 245+/Smm x 180+/•Smm x 180+/-Smm Resolution: (max): 1024 x 768 Dot Pitch: 0.28" ...... $469.00 NEW PRINTER RIBBONS LO 100 / ACTION PRINTER ...............$12.00 NEC PINWRITER P3 ........................... $17.95 NEC PINWRITER P S ...... ~ . ....... $19.95 SEIKOSHA BP5420...... . ... $19.95 CITIZEN 120D............ 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Matrix, 350 Cps Draft, 110 Cps NLQ, Scat able Fonts, 8 to 32 poin~ 11 LO Fonts, 360 x 360 DPI, Top, Rear, Bottom, and Front Paper Feedpt1tha, Convertabte Push/Pull Tractor LQ•870 80 Col, 24 Pin Dot .... .... $925 ink jet, 600 Cps Draft, US Cps LO, Push Tra ctor, Smart Park Feature. $19.95 $37.95 $10.95 $16.95 SAVE! SAVE SAVE! SUPA VGA Prices are without oaddle cards ..... T HO CONTROLLER ............... ....... $129 T HO CONTROLLER .................... .. $149 RS232/SERIAL CLOCK .... ........ ....... $49 MONO COLOUR CARD ...................$76 MULTI I/O CARD ................ ............ .. $99 RINTER CARD .... ........................... $29 EGA CARD ............ ....... .... .. ........ .. ....$179 !AGNOSTIC CARD.. .. .. .. .... .. .. .$795 L PRINTER ......~. ..$89 MAT EX/EXP... . . ., ....... $325 AX CARO ............ ::.::.-. · .. .. .. ..... $595 PORT SERIAL CAR0 ..................... $199 WAY FOO CONT (360) ..... .. ..... .......$39 S/232 SERIAL CARD ................... ..$39 1·9 boxee $18.95 $42.95 $12.95 $22.95 HARD DRIVE SPECIALS 286·16/21 .................................................... $119 386SX-16 .......... ............ !?':':'.~ . i..... $190 386SX·25/31.. ............... $225 386SX-33/39................. ) :;l!") $275 386-25 .......................... i[; ~ ....... $400 386·33 64K CACHE ...... ::-............................. $449 386-40 64K CACHE .............. : ............ .......... $465 386·33 128K CACHE ........................ ........... $495 486SX-20 ..................................................... $595 486SX-25 ............................. ......................... $595 486·33 64K CACHE ..................................... $1095 486-33 256K CACHE ...................... ............. $1195 486-50 256K CACHE .............. ..................... $1795 486-33 EISA ....... .......................................... $2495 f' 3 1/2"DD $19.95 3 1/2"HD $45.95 5 1/4"OD $14.95 5 1/4"HD $23.95 I ROD IRVING ELECTRONICS Pty. Ltd. ACN.005428437 HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH. 663 6151 1639 1640. FAX: 639 1641. OAK LEIGH: 240C HUNTING DALE RD, OAKLEIGH. PH : 562 8939 NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3868 BLUESTAR COMPUTERS: 271 MAROONDAH HWY. RINGWOOD. PH: (03) 870 1800 Postage rates $1 • $9.99 ...... $3.00 $10 • $24.99 ..$3.50 $25. $49.99 .. $4.50 $50 • $99.99 .. $6.00 $100 • $199 ... $7.00 $200 • $500... FREE $500 PLUS .. FREE The• poataa• rate•""' bulc poatag• only up lo ~o::ai:lgh~ lle- wll bo charged at cl"°"'"I r••• :~!~ TOLL FREE MAIL ORDER HOTLINE: 008 33 5757 LAMPS & GLOBES ~ Our range of lamps and globea have colour coded wires to denote what voltage they are 1\-----1,~' PCB Mounting rated at: Red wires: White wires: A piezo electric sounder for direct mounting on pcb'a. 6N138 OPTOCOUPLERS Z11660 .....................$6.95 TIP 120 T90517 .....................$2.90 Low profile PCB mounting buzzer A miniature aolid state PCB mounting buzzer having a loud but pleaeant 75dB tone and operating from a 12V DC supply. It is only 7mm high when mounted on the PCB. It will work with supply voltages ranging from 3 to 24V DC. Supply polarity la marked on the bottom of 1he case ■ a an aid to installation. Two 2 mm dia. hole& are required 18mm apart. The case la finished in • cream TEA 2000 PAUNTSC ENCODER U10175 .................. $15.00 colour. Resonant frequency: 3.5Hz Operating Voltage: 3to24VDC Current consumption at 12V: 5mA Sound Output 1112V DC : 75d8 at 30cm Temperature range : INS 16550 AFN UART U22187.................. $23.95 - NEW IC MC34063 U1 04,1 6...................$2. 95 As seen in Silicon Chip's Solar Battery Charger kit. 2 UNIVERSIAL BRACKETS WITH SCREWS TO MOUNT 3 1/2" HARD DRIVES INTO MOST COMPUTER CASES X19971 .................. .$9 .95 OIL INLINE BRIDGE I KBL06 1-9 6 AMP 600V.... $3.95 10+ $3.50 Service personal You need to keep a few of these In your parta box.~ 5 AMP TWIN DIODES .. $9 .95 -20 to 70° Diameter: 23mm Height: (withoU1 leads): 7mm Lead length : 8mm 1-9 10+ $3.50 S15260 ... $3.95 RADIAL RN HEATSINKS Anodized Black Thermal Rating 1° C/Watt 150mm Length Designed by Rod Irving: • 30mm length H10520 ......................... $6.90 • 75mm length H1 0525 ......................... $7. 90 • 100mm length H10529 .................... ..... $8.90 • 140mm lengt h H10534 ....................... $11.50 • 150mm length H10535 ....................... $12.95 • 170mm length H10538 ........... ....... .. ...$14. 95 • 195mm lengt h H10542....................... $15.50 • 200mm length H10543 .... ................... $15.90 • 225mm length H10546 .............. ......... $16 .90 , 300mm length H10560 .......................$19.00 • 1 metre length H10565 ....................... $49.95 • 2 metre length H10570....................... $95.00 Very Low Profile Piezo Sounder Resonant frequency: 4kHz±500Hz A piezoelectric sounder which can supply levels of over 1OOdB at a distance of 30cm, yet la only 4mm high. It can therefore be used wherever apace ia at an absolute premium. It requires an external driver which should operate on, or aa near aa poaaibte to, the buzzer's reaonant frequency of 5500 Hz. This source should present a maximum drive voltage of 30V peak-to-peak to the buzzer. Resonant resistance: 300U max Electrostatic capacitance: 17nF±30% Max input voltage: 30Vp-p Nominal drive voltage: 95d8<at>30cm Size: 24mm dia 5.5mm 1hick 1·9 10+ S15238 ... $3.95 $3.50 Resonant resistance: SCREWDRIVER TIP SOLDERING; IRON • 240V • 15 WATT T12907 ........................ $16.95 POINTED TIP SOLDERING IRON • 240V • 15 WATT T12905 ...........WAS .....~ THIS MONTH ONLY.. $12.95 DIRECT IMPORT PRODUCT! YOU SAVE! MY POWER 200 The MY-POWER 200 Is a pocket sized Inverter with punch . It will power a myriad of app liances Including TV's, Video's, drills, lights, laptops and computers, just to name a few! Continuous power rating Is 140 watts, However it will run most appliances w ith a name plate rating of 200 watts. Surge rating is a very real 400 watts. ............................ ..... $199.00 ::::.:.41t,--, ~I ~ ;-----------------J :DRIVER TRANSISTORS 10+ $3.50 L__ ____ ______ __ ___ 300Umax Electrostatic capacitance: 12000pF (±30%) Sound output at 30cm: 103dB max Height:4mm Diameter:23mm Length (lug tip to tip): 35mm Fixing centres: 29mm x BBA 1-9 10+ S15240 ..... .$3.95 CLEAR SUBMINIATURE GLOBES S14000............... 6V/80MA ..... $0.80 S14001 ............. 12V/85MA.....$1.25 S14002. ............ 24V/50MA ..... $1.25 • Di mentions: 6.3mm (L) x 3.2mm (Dia) • All have 120mm wire leads C~ ROUND GLOBE· BAYONET BASE S14006. ........ 12Vl50mA ....... $0.95 • Dimentiona: 23mm (L) x 11mm (Dia) • Clear gl ■ u lens. $3.50 ~ 90 ROUND GLOBE· SCREW BASE S14007....... 6V1100mA ..........$0.95 S14008....... 12Vl 105mA........ $0.95 • Dimentiona: 23mm (L) x 11mm Wire-Ended Piezo Sounder A piezo electric sounder Ideal for use in application• 12SC945 NPN 60 50 0.1 20-400 :1-9 $0.35 10+: $0.30 1Above Transistor will replace 2SC1815, 2SC2320, etc. T092 owing to Its small size. Resonant frequency: 4.6kHz Electro atatic capacitance: 20nF Normal drive voltage: 3-30V Pi> Ou1put at 10v p-p: B0dB<at>30cm Size: 31mm dla. 4 8mm thick -=1""'~· " CLEAR SUBMINIATUR E GLOBES S14003.............. 6V180MA ...... $1.25 S14004 ............. 12V185MA..... $1.25 S14005............. 24Vl50MA ..... $1.25 • Dimentions: 10mm (L) x 5.1mm (Dia) • All have 120mm wire leads (Dia) • Clear glaaa lene 0 ) where apace la at a premium : VCBO VCEO le hFE Package I V V a :2sc2625 NPN 450 400 10 10 T03P 11 -9: $1 0.95 10+: $9.95 • I Above Transistor will replace 2SC2555, 2SC3306, 2SC4138 etc. TDA2002 8 WATTCAR : l2SC4242 NPN 450 400 7 10 T03P RADIO AUD IO 1-9 to+ 1 :, .9, $7.95 10+: $6.95 AMPLIFIER $2.95 $2.50 1 I Above Transistor will replace 2SC3039, MJE1007, MJE1008, etc. 1-9 $3.95 tinned enda are provided. Mounting lugs with 2.5mm holea are moulded into the Resonant frequency: 5500Hz± 500Hz MORE TRANSISTORS lNEW IC'S lTDA2030 100mm lead-out wires with buzzer's cream-coloured caae. r--------. --------------1 NEW TRANSISTORS lsw1TCHING TRANSISTORS Bluewirea: Two 1mm diL holea are required 10mm apart 6 volt rating. 12 volt rating. 24 volt rating. GLOBE· T1 FLANGE S14009........... 6Vl60mA ....... $1.95 • Dlmentlona: 9mm (L) x 4mm (Dia) Clear glaaa lena Fixing centrea: 35mm x SBA 1-9 S15250 ...... $3.95 10+ $3.50 ARLEC DIGITAL SCALES GLOBE· T1 BI PIN S14010......... 6Vl60mA ......... $1.95 S14011 ......... 12Vl60mA.......$1.95 • Dimenalona: 9mm (L) x 4mm (Dia) • Clear glass lens ~ ...... llll ll l l l r . : ; ; , ~ ~ -- "" s.:_• .;· ~ ~ ELECTRONIC KITCHEN SCALES • Simply converts grams to ounces and ounces to grams by switching the selector key. • Various items can be individually we ighed in the same container using the reset key. A15075 .............. $69.95 SUBMINIATURE GLOBES· SCREW S14012. ......... 6 Voll .......... $0.95 S14013. .. ...... 12 Voll ........ $0.95 S14014 .......... 24 Voll.. ...... $0.95 • Dimensions: 20mm (L) x 6mm (Dia)• Designed for use with (IL2) holder• Clear glass lens . :STOP PRESS!: l ADELAIDE l : STORE OPENING: SEPTEMBER 28 lI : Ring for Details : lI L--------------J COMPUTER CASES b~::R Give your MEMORY mJ - ffelllllJJJJ :::::.·· computer that profeaeional ~ 41256-08 ......... $2.50 $2.25 $1.95 44256-08......... $7.95 $7.75 $7.50 44256-07......... $7.95 $7.75 $7.50 SIMM · : look '/ . X11105 .....$199 220W Power aupply I to suit X11102 .••... $199 l, BOTH FOR ONLY $295 RITRON EXECUTIVE CASE Includes P.S X11089-••....••••• $ 99 NEW STYLE MNI CASE WITH POWER SUPPLY X11103••..•.. _... $129 Relieve eye strain and headaches and increaae production with 1-9 theae anti glare screens. 14.. screen 1M x 9•70 $55 256K·70 $21 4M X 9•70 $219 SIPP 1M X 9.a0 $79 X99990 ...................$39.95 12'· screen POWER SUPPLIES X99995 ................... $14.95 c,1000 ....... ~ •·•• Power Supply for IBM', PC/XT & compatibles. DC Output :+5/13A •5.0 SA + 12V/4.5 ·12V O.SA X11096 ......................$139 COPY HOLDER YU-H32 _frJ Adjustable anna allows easy positioning • Copy area 9 112.. x 11 .. • Sliding line glide 200W Switch Mode Power Supply for IBM" AT' & Compatibles DC Output: +5116A •5.0.SA +12Vl4.5 ·12Vl5A •12I0.5A X11097 ......................$109 COMPUTER PAPER Cat No. U20550 U20560 U20590 U20540 U20542 U20544 HEAD CLEANER DISKS It only takes a minute amount of dust, dirt or magnetic oxide particles on your drive heads to • Attachea to the top your monitor • Put your copy right where you need il • Spring clip to hold paper • Velcro at mount for easy removal C21006 ................... $9.95 True A4 296mm x 210mm 250 sheets C21008 .................$14.95 True A4 296mm x 210mm MONITOR MOVER ARM Position your monitor exactly where yuo want lnt Maximize desk apace. • Solid steel structure • Height Adjustment • Span 33cm •Maximum load 50kg C21079 ....................... $199.00 C21009n19.95 ~ · DISK LABELS (To flt 3.5 .. diake) C21022 Oty. 25 .......................$1.95 ID===Jfa~ ,~ -='- ;=.====='=. <a :- ~ a . ~~-illlll .• . ~;;;;-~=~ ~ DISK LABELS & WRITE PROTECTS (To fit 5.25" disks) C21021 Oty. 25 labela & 25 write protects .................$1.95 ,- P10538 ............ $6.95 Theae are good quality SIMM sockets with metal clips at the ends and not the plastic ones which tend to break. DISK NOTCHER Converts 5 114.. single aided floppy disks to double aided, by placing an appropriate notch In the floppy disk jacket INTEL CO-PROCCESSORS C21070 ............... $7.95 PLASTIC DISK HOLDERS 3 /12" PLASTIC DISK HOLDER • ,,~\ ,,w~ U / !~~Jt~Jl50 ~ CASES /. Cl 2820 ........... $3.95 $3.50 $3.00 MEMOREX 3.5.. Plaatic disk holder • Holds 10 Doaka C12840 ..... $3.95 w 100+ • . 1 .·, 0 ~ c \ 3 1/2" DISK STORAG~ • 40 X 3 112.. disk capacity • High impact plaatlc lid & baae ·~ ' • Price $210.00 $459.00 $310.00 $335 .00 ~ ~ / ,- 10+ Type 287XL 387DX 387SX-16 387SX•25 r-"11".,..,.,._.._...,...,..._ C21002 ............. $29.95 1-9 Cat No. U21841 U21851 U21854 U21855 □ ·- • Holda 6 floppy [j) A-4 COPY PAPER 80GMSWHITE RECOMMENDED FOR HIGH SPEED COPIERS/LASER PRINTERS. ALSO AVAILABLE IN RECYCLED PAPER • Holda 5 disks Comes in 6 different colours C16050 Red C16054 Yellow C16052 Orange C16056 Green C16058 Blue C16060 Grey Only ............... $3.50 Each. • Made of Sturdy ··, black flexible plastic. • Holda 10 or more 5 1/4.. diska. • Display positions C21001 .................$39.95 ■III EPROM Type Price 2716 ......$11.75 2732......$9.00 2764...... $6.95 27128 .... $7.50 27256 .... $9.00 27512 .... $12.50 SINGLE P10536 ..... $5.95 $5.95 DISK ENVELOPES Protect your 5.25.. disks from dust with theae disk envelopes c21020 aty. 25 ....................... $1.95 ~~ '·'""::.::=;,,}·! 10+ $5.95 MEMOREX RECYCLED COMPUTER PAPER 2000 SHEETS Quality paper al a low price I • 60 gma bond paper • 11 X 9 112'• 2000 sheets $55 " DOUBLE 5 1/4" PLASTIC DISK HOLDER 500 sheets $69 $59 SIMM SOCKETS Introducing ComPstatl High quality 70 gam, convienienty packed continuous fan• fold computer paper. Cornea in packs of 250 or 500 sheets In two sizes. 279mm x 241 mm and true A4. Very uaeful for photocopying computer print-outs without having white apace on the top or bottom of the page. 279mm x 241 mm 250 sheets 100+ CMOS EPROM Cat. No. Type Price U20591 27C32 .... $14 .95 U20592 27C64 ....$5.50 U20593 27C128 .. $7.50 U20594 27C256 .. $9.00 U20595 27C512 .. $11 .50 U20546 27C010 ..$22.50 cause problems: errora, downtime or an expensive service call. Regular uae of s head cleaner will keep your drive free of trouble causing dirt and help keep your system up and running. These disk cleaners are simple to use, and Include cleaning solution and instructions. •31/2" 1-9 C12560 ......$6.95 • 5 1/4" C12555 .....$6.95 25+ $49 $48 $47 $19 $17 $14 $209 $185 $175 IC MEMORY COMPUTER ACCESSORIES • Copy area 9 1/2.. x 11 .. • Sliding line glide • Ast metal baae 10.24 , C16040.......................... $6.95 " • ...................................... $7.95 MOUNTING KIT 2 Universial brackets with Quickfhat<_~ QUICKTRAC 100 - \\ NEW POWER OUTLETS \ _,i~\ A new concept In Mice! Don't forget! Rod Irving Electronics are an established and respected company in the electronics industry and have been in the business for over 15 years. We stand behind our products and our warranty. QuickfhatM AVIATOR 5 • AUTHENTIC AIRCRAFT CONTROL YOKE • AUTOMATIC CONTROL YOKE CENTERING . • COMPATIBLE WITH IBM PC, XT AT AND 386" • 4 POSITIVE RESPONSE FI RE BUTTONS • REALISTIC ALTITUDE/LEVEL INDICATOR • 2 DUAL-SPEED TURBO FIRE BUTTONS • X•AND Y·AXIS TRIM CONTROL SWITCHES • 6·FOOT CABLE WITH JS.PIN CONNECTOR • STABILIZING SUCTION CUPS • 6 U.S MILITARY INSIGNIA STICKERS C14250 .•..•.•.••••••..•••••••• $89.95 • Requires Smart Games Card ...C14260 ..... $39.95 • OMNIDIRECTIONAL GRIP • COMPATIBLE WITH IBM PC, XT, AT AND 386". • AUTOMATIC CONTROL STICK CENTERING • 2 POSTIVE RESPONSE FIRE BUTTONS ."2 DUAL·SPEED TURBO FIRE SELECTORS • POP·UP FIRE BUTTON COVER • X ANDY- AXIS SWITCHES • 6·FOOT CABLE WITH 15•PIN CONNECTOR • STABILIZING SUCTION CUPS • 6 U.S MILITARY INSIGNIA STICKERS C14240 .............. $79.95 What do you do when you haven't got enough room on your desk to use a mouse? You get a Qulcktrac 100. The latest Innovation in mice technology. Unlike a normal mouse the Ouicktrac does not require any operating space other than that taken up by its tiny footprint. You simply have to use your fingers to control the curser rather than move your whole hand. Use your thumb to roll the tracking ball • The Quicktrac 100 Is responsive enough to detect changes without much thumb movement. The left and right control buttons can be controlled by your index and right finger, respectively and the key-lock button by your middle finger. They're are great for laptops and notebooks or anywhere where there is very little desk space. 100% Microsoft Mouse compatible. Includes Qtrac™ Driver software OMenu™ Pop-Up Library Menu making Utility DB9 to DB25 Adapter. System Requirements: Any IBM, PC, XT, AT or compatible computer • One 9-pin or 25-pin RS232 serial port. C14230 ............... $69.95 ~~ LAMINATOR - Is that precious photo of your loved ones In your wallet getting a bit tattery? Don't lose those precious memories protect them by laminating them with your own laminating machine Important Business cards, membership cards, recipes etc. last a life time longer when laminated. Now ROD IRVING ELECTRONICS have Imported this laminator that your budget can afford. Don't pay hundreds of dollars for some big machine Pay a 1/4 of the price for an attractive compact laminator that Is so simple to use. Heats up in only 2 to 3 minutes. SUPPORTS 4.77 TO 80MHz Complete with Calibration software FEATURES: • Intelligent software controlled game card • Compatible with IBM PC/XT/AT/386/486 • Complete with easy•to-<.1se menu driven calibration software on 5.25" floppy diskette • Software selectable clock speed • from 4. 77 to 80MHz • Automatic clock speed adjustment for advanced users • Hot•key program for fine-tuning clock speed during game • 2 15-pin joystick port-aupports 1 or 2 joysticks operation PIGGY BACK EXTENSION LEADS This is the new look in extension leads. Makes other extension leads look old fashion! lt'a a 240 Volt, 10A extension lead which Is fitted with a socket on one end and a piggy back double adaptor plug on the other. Turns your one point power point Into two while giving you the benefit of an extension cord. 1 Metre P18060 .................. $5 .95 2 Metre P18070 .................. $6.95 4 Metre P18080 .................. $9.95 6 Metre P18090 ..................$11.95 "CLICK DOUBLE ADAPTOR" Laminate Sheets .... 156mm x 112mm (4.25" x 6.75") for photos with punch holes for photo album Unique dual adaptor. More than just a double adaptor. Holds plugs more securely than old fashioned double adaptors • 1 x right handed adaptor P18022 ................................. • Twin pack with left & right hand adaptors Laminate Sheets ••• •135mm x 95mm (3 3/4"f -2-4-x 5 5/16") A_9_1-11_1_.·_··--··--···_·· __ ··_··_···_·$_1"'"1-.9-5-a-c-k-o---t P18024 ... A91100............................. 95.00 =..:..:.=.:.:.e:=======....:a==---------1 Laminate Sheets .... 95mm x 57mm (2.25" x 3.25") for business cards l-'-A-'-'9-'1-'-11-'-0'-•'.:.:.·••:.:;••;.:,c• .:.:.·••;..;.,;••.;;,.;••~·••;..;..;••""·$"'"1""'8--.9'-'5""'"'"'a""'c""'k~o'-'f_1'-'0""'0_ _ _ • Requires Smart Games Card C14260••.•$39.95 SMART GAMES CARD This is the big daddy of them all. Get the most out of your power points with this 12 way power board . Don't kill youseH by loading up the power point with Double adaptors. This is the save and neat way to use 12 appliances out of the one socket. Comes with a 1 metre fitted cord and plug and is rated 1Oamps, 2400 watts. Also has overload for photos and cards ss.so 0·· ~=• . . . . $9.95 A91113 •.••••••••••••••••••• $8.95 ack of 24 I- Laminate sheets .... 110mm x 170mm (4.25" x 6.25") A91112 ••••••••••••••••••••• $10.95 pack of 24 DO UP YOUR MONITOR & SAVE! NOW BELOW 1/2 PRICE! C14260 ••••••••••••••••• $39.95 US/EUROPEAN TO AUST. MAINS ADAPTOR Converts any two pin US or European plug to an Australlan tow pin AC plug • Designed for use with 240 volt AC operated appliances P18012 ......................$5.95 MONITOR STAND ADELAIDE STORE OPENING 28th of SEPTEMBER! PHONE FOR DETAILS ON (03) 543 7877. '-------- • Fits large monltora with feet separation up to 10" x 11" • Eliminate• neck craning • Eleva•• monitor for lncreaaed comfort. • Fully adjuetable while in uee • Stable 25• tilt 360" tum • Anti Skid feel D11100 12".......$9.95 D1110214" •••••• $12.95 ~ ANTI GLARE SCREEN Relieve eye atrain and headache• and increaae production with theae anti glare acreena 12'' Screen.................$9.95 14" Screen •••••••.••••••••• $19.95 ARLEC DEGAUSSING WAND for Colour TV. Double Insulated. Input: 240V 50Hz 2AMP Rating: 2 mln on 30 mln off T12316 ............... $98.95 4 year warranty! RITRON QUALITY . .. .. . . OPTIONAL EXTRAS RITRON EXECUTIVE ■ RITRON286-16'sare now only $1199 w:th a 4 year warranty. ADD PRICE TO BASE SYSTEM COST. PLUS $75 INSTALLATION. ::~ ~~N~~~g,~3r~11~• ;.i~::a.~c:~!~. , 1,-.·:: 1 MEG RAM EXP TO 8 MEG 31Mhz LANDMARK SPEED TEST Genuine 1.2M JAP F.D.D. 512K V·GA CARD Au st ralian, Fully 40M HARD DISK DRIVE, Upgradable 101 EXTENDED "CLICK" KEYBOARD DR DOS 5.0 MINI CASE & 200W POWER SUPPLY supplied wi th SUPA VGA COLOUR MONITOR every SY•t •m. 1024 x 768 Res 0,28" D.P DOS 5 $SO extra SERIAL PARALLEL GAMES PORTS 4 YEAR PARTS & LABOUR WARRANTY IBM' COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASESOFTWARE INCLUDED. • SHAREWARE SOFTWARE ASSEMBLED & TESTED IN AUSTRALIA. $1 3 7 9 • TAX INC. TAX EX Genuine Australian, Fully Upgradable DR DOS6.0 supplied with TIME every system. 1.2M JAPANESE BRAND F.D.D DOS 5 $50 ex1ra 101 EXTENDED "CLICK" KEYBOARD MINI CASE & 200W POWER SUPPLY SERIAL, PARALLEL, GAMES PORTS 512K VGA CARDSUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" 4 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. •SHAREWARE SOFTWARE WITH 200 MEG DRIVE $2,154 TAX INC. $1,819 TAX EX. TAXEX. $1 549 ' 85M HO add $130 126M HO add $175 105M HD•• $150 200m HD add $575 ISOM HD.. $475 $1 ,319 EXTRA RAM 1 MEG add •• $60 2 MEG add .. $120 WINDOWS 3.00.$69WINDOWS 3.1.$179 SOUND CARDS SOUND COMMANDER. .................... $149 THUNDER BOARD •••••••••••••••••••••••••• $199 SOUNDBLASTER II......................... $229 SOUNDBLASTER PR0 ..................... $369 FLOPTICAL DRIVE add ................... $849 21 M/BYTE DISC TO SUIT..... .......... $39 CD ROM SOUND BLASTER PACK •••• $979 TAX INC. TAX EX ~·· •~.~. §t~•§•· · · ~ G>~.§.§.r§?. . •••D $1,319 Gen uine •· 80486SX·20 CPU Australian, Fully . 1 MEG RAM EXP TO 32 MEG Upgradable •: 75Mhz LANDMARK SPEED TEST DR DOS6.0 40 MEG HARD DISK supplied with 1.2M JAPANESE BRAND F.D.D every system. •. 101 EXTENDED "CLICK" KEYBOARD DOS 5 $50 extr■ MINI CASE & 200W POWER SUPPLY 4 YEAR PARTS & LABOUR WARRANTY SERIAL, PARALLEL, GAMES PORTS, 1MEG VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP SPEADSHEET, WORDPROCESSOR & DATABASE SOFTWARE INCLUDED. •SHAREWARE SOFTWARE ASSEMBLED & TESTED IN AUSTRALIA. • $1 5 9 9 TAX :. INC. ' $1,359 <· SPREADSHEET, WORDPROCESSOR • DATABASE SOFTWARE. •• • $2,099 WITH 200 MEG DRIVE $2,174 TAX INC. $1,919 TAX EX. TAX EX. \ 80486-33 CPU / 256K ON BOARD CACHE. 1 MEG OF RAM 157Mhz LANDMARK SPEED TEST \ 40 MEG HARD DISK :• 1.2M JAPANESE BRAND F.D.D \ 101 EXTENDED "CLICK" KEYBOARD { SERIAL, PARALLEL, GAMES PORTS { 512K VGA CARD. IBM' COMPATIBLE •. SVGA COLOUR MONITOR (1024 x 768 Resolution) 0.28"'DP MINI CASE & 200W POWER SUPPLY 4 YEAR PARTS & LABOUR WARRANTY $1,869 EEEEREEizTER IT20EENEE•.,.z::;;r:.·.0·. ·.Mz·..·...·6.· rnkm s. ~::1 t:··..z::::RI :z:::T::::::::R::::::N z::. .z:. •.•·•m/2j:E .z. .t//.··· 90 •~rr;;s~~:;i .· .·.·.·.6 ·.·.·.·. J9W!:fffA§1:• . . r•·· 0 Pmm<at>/ · TI• •~Z'l;BTI •. EXECUTIVE ®~§§tl§~ II [jij v;~;;,aju) 80486•33 CPU 256K ON BOARD CACHE. 4 MEG OF RAM \ 157Mhz LANDMARK SPEED TEST •• Genuine .. 200 MEG HARD DISK Australian, Fully .. 12ms ACCESS TIME Upgradable 1.2M JAPANESE BRAND F.D.D :• DR DOS6.0 3.5" 1.44M JAPANESE BRAND F.D.D •• supplied wi th i 101 EXTENDED "CLICK" KEYBOARD t ern. . . every sya SERIAL, PARALLEL, GAMES PORTS 5 5_o_ex_t_ra-1 . . 1 MEG VGA CARD. IBM• COMPATIBLE ._D_os_ .. TOWER CASE & 220W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP 4 YEAR PARTS & LABOUR WARRANTY _s_ SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE. ASSEMBLED & TESTED IN AUSTRAUA. lM VGA CARD .. $150 TO CHANGE A 40M HARD DRIVE TO A RITRON EXECUTIVE 80386·40 CPU 64K CACHE ON BOARD 1 MEG RAM EXP TO 16 MEG 65 Mhz LANDMARK SPEED TEST 40 MEG HARD DISK 12ms ACCESS ~~. 512K VGA CARD .• $50 .·.·•· SOFTWAREINCLUDED. 'SHAREWARE SOFTWARE ASSEMBLED & TESTED IN AUSTRALIA. RITRON EXECUTIVE $1 ,579 . Genuine •• 1 MEG RAM EXP TO 16 MEG Australian, Fully :: 57Mhz LANDMARK SPEED TEST Upgradable • 40 MEG HARD DISK DR DOS6.0 1.2M JAPANESE BRAND F.D.D supplied with 101 EXTENDED "CLICK" KEYBOARD every system. ; SERIAL PARALLEL GAMES PORT DOS 5 $50 ex1ra • MINI CASE & 200W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP 512K VGA CARD (256 COLOURS) IBM' COMPATIBLE 4 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPROCESSOR & DATABASE ' $1179 ..·.·•·.·.·.· •··········. $3 395 ' $2 , 895 TAX INC. TAXINC. EXECUTIVE [ill~ l 04§.§.-J;IS1'.D 80486•50 CPU 256K ON BOARD CACHE. 4 MEG OF RAM 200+Mhz LANDMARK SPEED TEST Ge nuine 200 MEG HARD DISK 12ms ACCESS Australian, Fully TIME 1.2M JAPANESE BRAND F.D.D Upgradable 3.5" 1.44M JAPANESE BRAND F.D.D DR DOS6.0 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS supplied w~h 1 MEG VGA CARD. IBM• COMPATIBLE every sy,t •m. 5 _55_o_e_x1_r... TOWER CASE & 220W POWER SUPPLY ._D_o_s_ a SUPA VGA COLOUR MONITOR (1024 x 768 R..) 0.28" DP 4 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPRCESSOR & DATABASE IDEAL CAO MACHINE! $3995 $3350 ROD IRVING ELECTRONICS Est. 1977. MAIL ORDER HOTLINE: 008 33 57 57. ORDER FAX LINE: (03) 543 4871 ENQUIRES (03) 543 7877 HEAD OFRCE: 56 RENYER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH. (03) 6391640. FAX: 6391641. OAKLEIGH: 240C HUNTINGDALE RD, OAKLEIGH. PH: (03) 562 8939 FAX: (03) 562 81140 NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131. SYDNEY:74 PARRAMATTA RD, STANMOR~ PH: (02) 5193134. FAX: (02) 518 5024 BLUESTAR COMPUTERS: MELBOURNE: 271 MAROONDAH HWY, RINGWOOD, PHONE: (03) 870 1800 FAX: (03) 879 3027 SYDNEY: 115 • 117 PARRAMATTA RD CONCORD. PH: (02) 744 5526 FAX: (02) 744 5405 TAX INC. TAX EX. :-:::::;:;:;:::::::::::::::::: EXECUTIVE • / . .. \ ) ( •:.:.: )) ... /: ... "~':llli/. • 80486-EISA CPU 256K ON BOARD CACHE. 4 MEG OF RAM 167 Mhz LANDMARK SPEED TEST 200 MEG HARD DISK 12ms ACCESS TIME 1.2M JAPANESE BRAND F.D.D 3.5" 1.44M JAPANESE BRAND F.D.D 101 EXTENDED "CLICK" KEYBOARD SERIAL, PARALLEL, GAMES PORTS 1 MEG VGA CARD. IBM' COMPATIBLE TOWER CASE & 220W POWER SUPPLY SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28"' DP 4 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWAR~ ASSEMBLED& TESTED IN Al:ISTRALIA. IDEAL CAD MACHINE! FREIGHT CHARGE BASED ON 35KG COMPUTER SYSTEM Melb•Metro.$12.00 Sydney...... $17.00 Adelalde.... $17.00 Bribane..... $24.00 Canberra. ... $18.00 $2,674 TAXINC $2,319 TAX EX TAX EX. RITRON <at>~~sf~QQf v ~~:lllit} SOFTWARE. ASSEMBLED & TESTED IN AUSTRALIA. WITH 200 MEG DRIVE TAXINC. Vic country... $19.00 NSW country.$39.00 S.A country•• $39.00 OLO country.$55,00. W.A country.. $74.00 Darwin,_ .. _, $40.00 lnaurance:Perth ......... $31.00 $1 / $100 Value. Tasrnanla. •••$53.00 $4999 $4150 TAX EX All ••lel 1U: •Hmpt orCMfa to: RITRONICS WHOLESALE 56 " - ' - Rd, Clayton, Victoria. Ph: (03) 543 2168 Fu• (03) 543 2a.l MAIL ORDER 6 CORRESP9NPENCE P.O BOX 820, CLAYTON, VICTORIA. 3161. Error• Ii cmmlnon1 •Clllplld. Prtc.. & •~tlcalan1 oubjecl I D ~ ~IIM. PC, XT, AT, . . rwgl ■traclam#kl of lntarnattonal IUll,_n MM:hlnN.. PRICESATAUSh UBI0.74 A tutorial on PC-based data acquisition This tutorial will cover the basics of instrumentation using plug-in data acquisition boards and personal computers. We will talk about transducers, signal conditioning and software. By DAVID POTTER & ASH RAZDAN Data acquisition hardware can be categorised into four distinct types: plug-in data acquisition boards, IEEE 488.2 (GPIB) controlled instruments, VXIbus instruments and RS-232 controlled instruments. This tutorial will mainly discuss plug-in data acquisi16 SILICON CHIP tion boards and will also compare the different computers used for data acquisition: XT /AT/EISA and IBM PS/2 computers (DOS and Microsoft Windows), Macintosh computers, and workstations. Let's first talk about the compo- nents of a Data Acquisition System. The fundamental task of such a system is the measurement or g~neration of real-world physical signals. Before a signal can be measured by a computer-based system, a sensor or transducer must be used to convert it into an electrical signal, such as voltage or current. A signal is measured because it conveys useful information. This information is extracted from the signal by a data acquisition system. Any signal can generally be classified as analog or digital. A digital, or binary, signal has only two possible discrete levels - a high (on) level and a low (off) level. An analog signal, on the other hand, can vary continuously in voltage level and frequency. Transducers Transducers convert physical phenomena such as temperature, force, sound, pressure, light, position and fluid flow into a measurable electrical quantity, such as voltage or current. Examples of transducers include thermocouples (temperature to voltage}, thermistors (temperature to electrical resistance), strain gauges (strain to voltage) and microphones (sound pressure to voltage). Table 1 lists different phenomena and the transducers used to convert them into measurable quantities. Signal conditioning The signals produced by these transducers are often not well conditioned or well suited for measurement by data acquisition boards. Therefore, signal conditioning circuits or peripherals are used to amplify, linearise, isolate and filter the signal so that it can be properly and accurately digitised. For example, low-level thermocouple signals must be amplified and linearised so that a simple scaling function can be used to convert the signal voltage to temperature. The system being monitored may contain high-voltage transients that could damage the computer or harm the operator, hence the need for signal isolation. In another example, con- Fig.I (facing page): PC-based data acquisition systems include external signal conditioners, plug-in AID boards, a computer and application software. Also depicted here is National Instruments' SCXI signal conditioning hardware which is optimised for low level analog signals. National Instruments has data acquisition hardware for PC/XT/AT, EISA, PS/2 and Macintosh computers. These boards feature various combinations of analog, digital and timing inputs and outputs, and can be easily integrated with SCXI signal conditioning products for isolating, amplifying and multiplexing signals. ditioning is often used to filter unwanted signals; the signal conditioning peripherals can contain low-pass filters that eliminate high frequencies that could otherwise produce erroneous data. Signal conditioning products Signal conditioning products can be split into four classes. The first class, plug-in board conditioning, puts the signal conditioning circuitry directly onto the data acquisition board. While this is low-priced and requires the smallest amount of space, it has several disadvantages: signals are not fully isolated because they are plugged directly into the board connector which is located on the back of the computer; signals must be conditioned in the noisy environment of the computer. Only a few signals can be han- TABLE 1 Phenomena Temperature Light Force Position (Displacement) Fluid Flow pH Transducer Thermocouples, thermistors Photodiodes, phototransistors, light dependent resistors (LDRs) Strain gauges, piezoelectric transducers Potentiometers, linear voltage differential transformers (LVDT), optical encoders Head meters, rotational flowmeters, ultrasonic flowmeters pH electrodes dled because there is not enough room at the back of the computer to connect a large number of cables. The second class, digitising, conditions and digitises the signals in an external box and sends the data to the computer via a serial bus such as RS232. This class is capable of a very large channel count and being used for distributed I/O whereby large numbers of sensors are fed into the external boxes, and the data sent by multiple RS-232 lines back to the computer. The main disadvantage is in the serial data bus which limits the amount of information which can be transmitted. The third class , digitising and processing, conditions, digitises and analyses the signals in an external box. Like the digitising class, the digitising and processing class is capable of a very large channel count and can be used for distributed I/0. This class also overcomes the problem of low througliput to the processor of the previous class. Unfortunately, this class has a major disadvantage in that the developer must program a processor that is not part of a general-purpose computer. Therefore, the developer will not have the wide range of software which is available for PCs. The fourth class, direct-connect modular, is a two-port system that SEPTEMBER1992 17 older special purpose signal conditioning products are obsolete because of too-rigid architecture. • Signal conditioning systems must be robust enough to handle conditions on the factory floor. Rugged casing, secure cabling and rack mounting are all required to make a system long-lasting and reliable. Data acquisition boards NI-DAQ is a real-time, multifunction data acquisition driver for Microsoft Windows which controls National Instruments' plug-in data acquisition boards for PC/XT/AT/EISA and IBM PS/2 computers. Also available from National Instruments is DAQWare, a DOS-based software package which has menus for chart recording, temperature measurement and waveform generation. It outputs data in binary, ASCII or Lotus 1-2-3 formats. accepts unconditioned signals on one port and sends out conditioned signals on a second port to a plug-in data acquisition board in a PC. They can take advantage of the wide range of data acquisition boards and software available and the latest PCs can be used for analysis and presentation. They also can usually be configured for different transducer types for each channel and are capable of high throughput to computer memory. The disadvantage to this class is that it cannot generally be used for distributed I/O and can only condition a few channels. / What to look for in signal conditioning systems • High sensitivity and low noise requires extensive shielding from the . PC i...--~ Interface Circuitry PC Bus ADC electrical interference of the PC. • Power supplies and digital circuitry must be designed for optimum noise performance. The signal conditioning system should be expandable to be able to take advantage of the high sampling rate of today's plug-in data acquisition boards. • The fast data processing capabilities of a PC should not be reduced by the signal conditioning front end. Therefore, the signal conditioning system should have high performance with a high analog bandwidth. • A signal conditioning system must be flexible, offer a wide range of functions and interface with many types of computers and software packages. • The system must be able to be easily updated to keep up with the rapid changes in the PC industry. Many Analog Mux I/O Connector Fig.2: this diagram shows the analog input section of typical plug-in data acquisition board. 18 SILICON CHIP These boards plug directly into a slot in a PC and are available with analog, digital and timing inputs and outputs. The most versatile of the plug. in data acquisition boards is the multifunction I/O board. As the name implies, this board typically contains various combinations of analog-to-digital converters (ADCs) , digital-to-analog converters (DACs), digital I/O lines and counter/timers. ADCs and DACs are used to measure and generate analog voltage signals , respectively. The digital I/O lines sense and control digital signals. Counters/timers are used to measure pulse rates, widths, delays and generate timing signals. Multi-function boards are commonly used to measure· analog signals. This is done by the ADC which converts the analog voltage level into a digital number that the computer can interpret. The analog multiplexer (MUX), the instrumentation amplifier, the sample and hold circuitry and the ADC comprise the analog input sec- , tion of a multi-function board, as shown in Fig.2. Typically, multi-function data acquisition boards have one ADC. Multiplexing is a common technique for measuring multiple input channels (generally 16 single-ended or eight differential) with a single ADC. The analog multiplexer (MUX) switches between input channels and passes the signal to the instrumentation amplifier and the sample and hold circuitry. Instrumentation amplifiers typically provide a differential input and gain selectable by jumper or software. The output of the amplifier is sampled, or held at a constant voltage, by the sample and hold device at measurement time so that voltage does not change during short the digitisation period. The ADC digitises the analog signal into a digital value which is ultimately sent to computer memory. FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT e PHILIPS Flexible Data Acquisition? Fluke's Hydra Series has all the answers Whatever your questions about flexible, portable data acquisition, Fluke's Hydra Series has the answers. The economic 2620A Data Acquisition Untt is a compact front end for use wtth your PC or printer. Or for stand-alone or remote monitoring applications, the 2625A Data Logger stores over 2,000 scans in nonvolatile memory, Both systems are easy to set-up and reconfigure - at the touch of a buaon, or remotely via the computer interface. Check all the answers that Hydra offers: ■ Plug-in universal input module for up to 20 analog inputs without signal conditioning. ■ ■ ■ For further information please contact your local Philips Test & Measurement Organisation: SYDNEY (02} 888 0416 MELBOURNE /03} 8813666 PERTH (09} 277 4199 WELLINUTON (04} 88 9788 BRISBANE (0ll 8440191 ADELAIDE (08) 348 2888 AUCKLAND (09/ 89 4160 ■ Twelve digital 110 lines: four fixed alarm outputs and eight computerconfigurable alarm or general-purpose lines. Standard RS-232-C interface for printer hook-up or bidirectional computer control; GPIB/IEEE-488 optional on 2620A. Fu/I front-panel control for alarm limits, scaling, min./max./last memory, auto-print outpuC real-time clock and selectable scan triggers. Free Hydra Starter Software Package and labtech ACQUIRE™ for quick, easy set-up. PHILIPS Lab VIEW - Windows Software for Data Acquisition Boards Top-Level Front Panel Top-Level Block Diagram Run Edit Free Single Execution Print Run Step Highlighting Indicators Fr~~! Panel Data Flow Formula Acquisition Analysis Terminal Wire Node and Control Icon Icon In the 1980s, plug-in data acquisition boards for personal computers became a widely accepted method for automating test and measurement applications. These instruments are very flexible because of the way in which the computer can process the data. However, suitable software was lacking, that could easily provide the analysis and user interface, in addition to the ability to program the data acquisition hardware and integrate existing programmable instrumentation. The introduction in 1986 of LabVIEW for the Macintosh revolu- The fundamental parameter of an ADC is the number of bits. For exam- f ple, many ADCs are 12-bit, so a voltage within the input range of the ADC will produce a binary value that has one of 212 = 4096 different values. The more bits that an ADC has, the higher the resolution of the measurement. The resolution of the AID conversion is also determined by the input range of the ADC and the gain of the instrumentation amplifier. The gain is applied to bring the signal up into the optimum range to suit the ADC and thereby give best resolution. For example, suppose you are measuring a low-level ±30mV signal with a 12-bit AID converter that has a ±5V input range. If the system includes an amplifier with a gain of 100, the re20 SILICON CHIP tionised PC-based instrumentation with the concept of graphical programming - developing block diagram programs rather than writing conventional, text-based code. Lab VIEW was the first graphical programming language that could integrate several popular classes of hardware for test and measurement applications. Now Lab VIEW is available for both Microsoft Windows-based IBM-compatible PCs and UNIX-based Sun SPARCstations running tMe X Window System or OpenWindows. To run Lab VIEW for Windows you need a 386 PC with a 387 co- sulting resolution of the measurement will be 10V/(100x4096) = ±0.0244mV. Finally, an important parameter of digitalisation is the sampling rate. This must be at least twice as fast as the highest frequency present in the signal (this is the Nyquist Criterion). In addition, the instrumentation amplifier must be able to settle to the required accuracy within a specified time. Types of ADC The most popular ADC on plug-in data acquisition boards is the successive approx;imation type because it offers high speed (up to 200 kilosamples/sec) and high resolution (12-bit) at modest cost. Subranging (also called half-flash) ADCs offer very high speed conversion with sampling processor, 8 megabytes RAM, 10 megabytes hard disk space, Microsoft Windows 3.1, and DOS 5.0. A Super VGA display and a Windows 3.1 compatible graphics accelerator are recommended. The minimum configuration for LabVIEW for Sun is a SPARCstation with 24 megabytes of main memory, 32 megabytes disk swap space, and 10 megabytes disk space (for the application and associated files) . LabVIEWforSunwill run under MIT's X Window System, Version 11, Release 4 or 5 or Open Windows Version 3. It does not require Motif or OPEN LOOK. speeds up to 1 megasamples/sec. Delta-sigma modulating ADCs are the state of the art. They sample at high rates, are able to achieve high resolution and offer the best linearity of all ADCs. Integrating and flash ADCs are older types still used on data acquisition boards today. Integrating ADCs are able to digitise w ith high resolution but must sacrifice sampling speed to obtain it. Flash ADCs are able to achieve the highest sampling rate (GHz) but are available only with low resolution. · Noise & wiring considerations Even after the correct signal conditioning and plug-in boards have been selected, care must be taken to avoid noise corruption. Power lines, computer monitors and electronic equip- I like the feeling of our new igital troubleshooting scope. Now there's a 100 MHz digital scope that handles just like analog. .instantly to the slightest control change. Digital oscilloscopes have certain advantages that are hard to overlook. But for troubleshooting, many engineers still prefer analog scopes. Simply because they like the way they handle. But when it comes to troubleshooting, the HP 54600's digital performance leaves analog and hybrid scopes far behind. At millisecond sweep speeds, the display doesn't even flicker. Low-rep-rate signals are easy to see without a hood. The HP 54600 changes that. It looks like a 100 MHz analog scope. All primary functions are controlled directly with dedicated knobs. And itfeels like one. The display responds It has all the advantages that only a true digital scope can provide. Like storage, high accuracy, pretrigger viewing, hard copy output, and programming. And since it's one of HP's basic instruments the HP 54600 gives you all this performance at a very affordable price. So if you like the feel of analog control, you'll like the way our new digital scope handles troubleshooting. To find out more call the Customer Information Centre on 008 033 821 or Melbourne 272 2555. [hp] ~i~K~~6 A Better Way. Just released: the HP 54602A scope with bandwidth up to 250MHz JWTHTM 125/A LARGE LCD DISPLAY MODULE A ve ry small telescopic STEPPER MOTORS These are brand new units, main body has a diameter of 58mm and a height of 25mm. Will operate from 5V, has 7.5 deg. steps, coil resistance 6.6 monocular IA viewe r. The assembled scope has high quality military grade optics, and employs a prefocussed IR image ohm and it is a two phase type. Six wi res. converte r tube. Thi s tube has a useful response ONLY from 600-1300 nM, thus also making it useful when working with IR LEDs, and IR laser systems. The scope has provision for a coaxial E.H.T. connection , and is supplied with a power supply kit, that features a ready assembled inverter on a small PCB. The power supply $12 ea. (Item No. 0140) easi ly fits into a small plastic case, and can be fitted with $269 r,~c~:~~I~ i~~~~uffi~:t At a ve ry small (Item No. 0121) We can also supply the in some laptop computers. Yellow•green same monocular viewer wi th its original power supply. Powered by a single 1.5V C type battery. In this case all that is needed is connecting the scope to the power supply unit via a coaxial cable, which is also supplied. (Item No. 0122) VISIBLE LASER DIODE POINTER-PEN r \ \ Brand new large Hitachi LM215XB display, as used Save by making your own LCD reflective type, 480 X 128 dot display, effective display area of 242 X 69 mm , has 14 LSI ICs 12V laser inverter kit. Th is combi nation incl udes a He-Ne visible red laser mounted on the rear of universal laser power the PCB. Includes four pages of data sheets. Limited stock at a sma ll ~~~~t~a~u~. their $39 ea. SINGLE CHIP MICRO COMPUTER (Item No. 0132) tube and one 12V supply kit - Mkll. This inverte r features easy construction since the transformer is already assembled and will drive all the 0.2-15mW tubes efficiently. Universal 12V supply plus a used 2-3mW tube or head sgg Small PCB assembly containing two ICs, one of which is a M usic generator (7910 CF). Th e other IC is probably a power amplifier (NECCTM701D). App ly 3-12V across two of connector pin s to obtain music from one of the IC pins. This information and a circuit diagram is provided. 5 $30 extra. Only with initial purchase. (Item No. 0105X) ..........-.............. 'C:"•.··-. t>:;/·:·-:•,.""• ~ and en hance all your presentations. Not a kit, but a comp lete commercial pen sized In the form of a telephone display. Based on an NEC uPD7503G single chip micro computer. Apply power to the un it and the lase r pointer at an display will show date and time (Xtal controlled osci llator on board) but incredible price! ON SPECIAL AT s1ao Small pen sized body. Runs on two small AAA battery. Battery life: 2-10 hours. Vis ible 5mW red (670nM) laser. Projects a visible red spot at more than 50 metres. As used for medical treatment by doctors and acupu ncturists. this is on ly a sma ll part of the mi cro comp uter's features: 4 bit single ch ip micro computer, 4 bit parallel ALU, 8 bit serial interface, 4096 X 8 bit words of ROM , 224 X 4 bit words of RAM , 23 general purpose 1/0 lines, 24 line segment outpu ts 15 switches: 5 off modern 3A panel mounted mains rated switches, 5 off modern 16A panel Powerful ball bearing identical small mains powered fans. transformers and four identical larger transformers . The transformers can be rewound for use in switches worth at least five tim_es our total price of s 16 FOR TH E COLLECTION Item No. 0150 LARGE ROT ARY SWITCHES 1mA whilst operating ,tfess than 10uA in standby. Connection to the .phone display can be made by with each order for one or more of the phone These brand units a re supplied in their original pack ing . Th ey are an option for backlighting Citizen LCD colour TVs. The sc reen glows a bri lli ant whi te co lour when the un it is powered from a 6V battery.' Draws approximately 50 mA. The displays. $ 15 They have at least th ree positions and are have currents rati ngs from 10-35A. Great for high power main s, and antenna switching. (Item No. 0133) pressure switch. horizontal adjust• 15 ONLY ea. Item No. 0151 Vertical and basis of a solar powered sign , e.g . house number. Effective sc reen size is 38 X 50 mm. The inve rte r PCB can be also used for powering backlighting ea . ments. Battery life more than 10 hours continuous. 5mW 670nM class III A laser. Range is about 150m, some would claim three times more. Shock tested to 2000g. One year warranty. ON SPECIAL AT (I tem No. 0144) 5 Small black anodised metal body. Removable PCD can be separated. Could be used as the 12 These large rotary switches have "snap in " action and all are rated at mains voltages . or higher. ONLY OR 5 for $60 sc reen and the inve rter S ea. new eq uipment. sg • 90 !~~:,r\~~:r~~~rc~· s5 Item No. 0152 $249 Price includes one rifle or pistol mount (Item No. $89 (Item No. 0111) We can also supply a similar kit which is based on an unmou nted co lli matin g lens which wi ll need to be supported in front of the laser diode. This kit includes a brand new 5mW/780nM IR laser diode, a suitable heat sink, a collimating lens, a driver kit (PCB and components) and the instructions. ea . Item No. 0147 Brand New high quality US made, amorphous glass Solar Panels. Dimensions: 150 X 150 X 2.5mm . In normal sunlight they deliver a full 1 Watt whilst charging 6V-8V consumption: less than instructions on the 220V/0.13A, 173mm diameter by 60mm deep. Thermally protected, finger guard included, removed from ad hesives are used between them or in coi l winding. There are four SOLAR PANEL GIVEAWAY addressing, can be battery operated (3.5-6V), extremely low battery uPD7503G and a circuit diagram of the phone display will be provided dissamble and rewind. Ferrite halves are clipped together and no That's a total of t5 New instru ction set enables direct memory simpl y pushing wires into ONLY Contains mainly 8 modern ferrite transformers which are very easy to LARGE COMPUTER FANS and 4 lines common the socket provided . One complete 15 page set of bar code reading , medical, etc. Limited stocks. mounted mains rated switches, and a mixture no less than 5 rotary switches: small and large. outputs for driving LCDs, (Item No. 0101) Unive rsal Supply Kil plus a new 10mW tube $299 (Item 0107) nM/5mW. We also supply a PCB components and instructions kit, for a suitable digital dri ver circuit that can be used to complete the laser transmitter. Suitable for Universal Supply Kit plus a new 5mW tube $189 (Item No. 0106) A mixture of no less than printers. but is suppl ied with an extra Brand New laser diode to su it . It produces a beam the.I can be foc ussed to a fin e dot or line. Barely visible, 780 comm unications . data links, perimeter protection , Universal Supply Kil plus a new 1mW·tube $129 (Item No. 0105) Suit teachers, doctors, businessmen, and other professionals. Improve r~igsd~s~lays 4 ea. Item No. 0146 One extra tube or head This precision collimator assembly was removed from working laser ONLY $45 Note that if either of the above lasers are coupled with a sui tab le receiver (E.A. Ap ril 91) a perimeter batteries! Can be connected in se ries, in parallel. or series / parallel. to increase the voltage, and/or current capac ity. For example, in ave rage sunlight , two of these panels connected in series will deliver approximately 150mA of charging current, into a floating 12V (14V) battery: 2 Watts! Four panels can be protection or data link wit h a range of a few ki lometres should be poss ible. We tried it ove r 300 metres. with no problems! We may stock a kit for the rece iver which would include the instructions. in July 92 . Approx imate pr ice S20 for the PCB. all on-board components . and a suitable relay. connected in series parallel to deliver 300 mA into a floating battery: 4 Watts' Compare the prices! All the panels have a weather protection film on rear, and the terminating clips are provided. $10 INCREDIBLE PRICING: or 10 for $85 (Item No. 0130) ea. DANGER! LASERS ARE NOT FOR KIDS then average the data for a single reading. This is effective for filtering out higher frequency noise, such as 50Hz interference. Software filtering of noise is not practical for all applications though. It works best for lowbandwidth signals that can be oversampled many times. Digital input & output signals Many data acquisition boards include several channels of digital input and output. These channels are usually TTL (0-5V) lines and are typically groupThe automotive fluids research program at EG&G Automotive Research Inc (San Antonio, Texas) is the type of industrial environment that tests the performance capabilities of SCXI, a ed into 4-way or 8-way low-noise, front-end signal conditioning system. ports. Each port may be dedicated as an input ment can add noise to the signals you potential difference adds unwanted or output port or may be software are acquiring. Switching high-current noise to the measurement. configurable. loads in nearby wiring can generate Some applications require that the magnetic fields that are coupled into Minimising noise reading or writing of digital patterns your signals through loops in your via software be synchronised with an external cabling. Signal wires close to AC Noise can be further minimised us- clock. Therefore, some boards include power lines can capacitively pick up ing software techniques. While soft- handshaking lines to time the reading noise. ware often assumes that the noise dif- and writing to the digital port. To minimise these problems, all sig- fers in some known way from the As mentioned earlier, you may need desired signal, the simplest technique signal conditioning circuitry for your nal wires should be as short as possible. You may also want to use shielded is just to average readings over a pe- digital channels, usually to provide or twisted-pair cabling for better noise riod. isolation. The digital 1/0 channels of performance. You should be careful Consider an application that rea data acquisition board may also be to avoid ground loops in your signal quires a temperature reading once per used to control relays to switch loads connections. A ground loop occurs second. Instead of performing a sin- such as solenoids, lights, fans, mowhen the signal source is referenced gle reading every second, the soft- tors, pumps and so on. to a ground that is at a different poten- ware can sample the temperature senRelays may be either electrometial to the measurement system. _This sor several times at a higher rate and chanical or solid state. Solid state input relays can also be used to sense large voltages (AC or DC) from proximity switches, thermostats or limit computers which don't provide the switches and convert them to digital Budget 16-channel standard ±12V power supply rails. TTL signals. Both electromechanical A/0 card The PC-126 is also compatible with and solid-state relay boards are availThe PC-126 is a 12-bit 16-chan- the PC-26 and PC-30 range of data able from vendors for direct connecnel AID card capable of sampling acquisition cards. tion to digital 1/0 ports of data acquirates of up to 50kHz with two 12-bit Supplied with the PC-126 is driver sition boards. D/A channels and 16 digital 1/0 lines. software (compatible with most comData acquisition software The inputs and outputs have DIP pilers), driver source code and the switch selectable ranges. Advanced Status 30 data acquisition software. Software is often the most critical triggering and clocking modes are . Drivers are also available for the component of a data acquisition sysintegral to the card as well as a DIP PC-126 to run under Labtech Notetem. A whole spectrum of software switch selectable bus address to book and Labwindows. options exist, each with important avoid bus contention. For more information, contact trade-offs and advantages. The card has a low power conBoston Technology, PO Box 415, The first option is to program the sumption and can be used in laptop Milsons Point, NSW 2061. data acquisition board yourself at the hardware level. Data acquisition SEPTEMBER1992 23 Relay output board from Procon Procon Technology has released an externally mounted high cu rrent relay board , the PC-10-NR. Designed and manufactured in Australia, this board provides eight relay outputs capable of switching 1A at 11 0VAC or 30V DC. Also included are eight optocoupler inputs with 1000V RMS isolation. Up to seven of these boards may be used in conjunction with Procon 's bidirectional parallel port cards. A new feature of the board is the ability to turn off all outputs if new data is not received within 10 seconds (user selectable) . This function may also be disabled, allowing outputs to remain in their last state indefinitely. For further information , contact Procon Technology, PO Box 655, Mt. Waverley, Vic 3149. Phone (03) 807 5660. repeatedly fills the buffer as the program accesses and processes the data. This method allows large amounts of data to be processed with limited amounts of memory. Another important feature of driver software is the ability to maximise hardware performance. To do this, full support ofDMA-driven and interruptdriven data acquisition is required. However, there are certain DMA techniques and features that can optimise hardware performance on different hardware platforms. For example, EISA bus computers include a faster, more advanced DMA controller. While this DMA controller is compatible with AT and XT computers, the DMA controller implements certain features , such as buffer chaining, that are valuable for high speed data acquisition. Macintosh II computers, on the other hand, do not include a DMA controller. Therefore, driver software and the accompanying hardware must provide the services to attain full hardware throughput rates. Acquisition~analysispresentation software boards are typically register-based, ie, they include a number of digital registers that control the operation of the board. The developer may use a standard programming language, such as C or BASIC, to write series of binary codes to the data acquisition board to control its operation. While this method affords the highest level of flexibility, it is also the most difficult and time consuming, especially for the inexperienced programmer who must know 1 the details of programming all hardware , including the board, the PC interrupt controller, PC memory and so on . Driver software If you don 't have the time or interest to learn the details of your computer and plug-in board hardware , you can use data acquisition driver software. Driver software typically consists of a library of function calls usable from a standard programming language. These function calls provide a high-l evel interface to control the standard functions of the plug-in board. For example, a function called SCAN_OP may configure, initiate and complete a multiple channel scan24 SILICO N CHIP ning data acquisition operation of a predetermined number of points. The function call would include parameters to indicate the channels to be scanned, the amplifier gains to be used, the sampling rate and the total number of data points to collect. The driver responds to this one function call by programming the plug-in board, the DMA controller, the interrupt controller and CPU to scan the channels as requested. Some driver software consists of little more than a collection of routines to exercise the very basic operations of the data acquisition hardware. At the other end of the spectrum, some drivers act as a complete operating system. These provide transparent DMA (direct memory access) and interrupts for multiple boards and multiple functions (analog in, analog out, digital) on single boards. They may also provide different buffering techniques, such as doublebuffering, to maximise performance of the hardware. With double buffering, data is streamed into a memory buffer using DMA or interrupts concurrently while the application program pulls out data from the buffer. 1,'he DMA or interrupt-driven process While driver software simplifies the operation of collecting data using plug-in boards, a typical acquisition involves more than the simple acquisition of voltage readings. For example, most applications also involve some type of processing, manipulation, display and storage of the collected data. A user of driver software will code these operations with the programming language they happen to be using. However, several software packages are available that address the development of entire applications. These packages simplify not only the acquisition of data but also the development of a complete data acquisition application. Anyone using one of these software packages configures and develops an application ranging from menus to standard programming languages to graphical programming. With graphical programming, the user places graphical icons representing different acquisition and processing operations on a workspace. Lines are drawn , or wired, between icons to represent the flow of data in the program. For example, a user might wire output data from an icon that collects temperature measurements to an icon This is an example of a temperature measurement application configured with the LabVIEW graphical (icon-based) programming system. Lab VIEW Vis (virtual instruments) have graphical front panels as the user interface and a block diagram as the program. You can customise your graphical user interface with graphs, strip charts, knobs, slide controls and imported graphical images. that averages a series of measurements. The icon may also be wired to a terminal to display the measurements on a strip chart. One of the first decisions to be made when configuring a data acquisition and control application is to decide which computer system will be used. -...... = . . === -----·. ·:-..T"..a..1 00000 00000 aioai..:ai -.:;t N ,- NT""" YHFHFHF>YI- ~ ;, r:i;l3 =ii~•£= Pfii{{jfeeson s PC MARKETPLACE P/L TEL(02) 4186711 FAX (02) 4186713 Mail Order Address: P.O.Box1100 Lane Cove NSW 2066 ,Major Credit Cards accepted. Prices apply for mooth of issue Dealer enquiries welcome. ATTENTION: FAX / MODEM OWNERS If you are using QL2 Software, then upgrade to the latest Version 2 for only $40.00 including P&P. This new version has a number of new features. These cover the range of 80x86-based PC/XT/AT/EISA computers, IBM PS/ 2 computers and Macintosh computers. You will want to consider the bus architecture, the processing power and operating system of a platform before making a decision. The I/O bus architecture of the different computer platforms can be a factor in the performance of your application. The 16-bit AT bus, used in most of today's 80286, 80386 and 80486 computers, has a maximum data transfer rate of about 1.6 megabytes/ second. Boards built with 8-bit XT bus in- . terfaces can be used in AT computers and both XT and AT boards can be used with the 32-bit EISA bus. The EISA bus, used in 80386 and 80486 computers, has a maximum rate of 33 Mb/sec and expanded DMA capabilities. EISA boards also can be configured automatically with software without having to use jumpers or switches. IBM PS/2 computers use the Micro-Channel Architecture bus, a 16 or 32-bit bus with capabilities similar to the EISA bus. Apple's Macintosh II and Quadra computers use the NuBus, ~ ~~~ ~ - - - - ~-11"";.;.....•-! IN ANYONE'S LANGUAGE. PROCON TECHNOLOGY LETS YOU TAKE CONTROL! We manufacture a wide range oflow-cost digital 1/0 boards. Each board features: 8 opto-isolated inputs (12/24/48V AC or DC), 8 relay outputs (switching up to 10 Amps at 250VAC), LEDs indicate 1/0 status and IBM-PC software is included. An industrial version with plug-in relays is also available. The system features: External mounting (up to 30 metres from computer) operating through any IBM-PC bi-directional printer port and capable of expanding to 240 1/0. Applications: Home or business security systems, process monitoring and control, laboratory automation, quality control testing, robot control and energy management. SUPER SPECIAL 101 Enhanced Keyboard Was $99.00 NOW ONLY $59.00 GRAPHIC CARDS/ MONITORS VGA 512K VGA 1MB 14" Mono Monitor 14" SVGA Monitor $ 95.00 $ 149.00 $ 195.00 $ 499.00 FLOPPY DISK DRIVES 1.4MB3.5" 1.2MB 5.25" 3.5" TO 5.25" Bracket $ 105.00 $ 120.00 $ 9.00 PROCONtechnology Box 655, Mt. Waverley, VIC. 3149. TEL: (03) 807 566o FAX: (03) 807 8220 • Yes! High-speed drivers are available for GWBASIC, Quick.BASIC, TurboBASIC, QuickC, TurboC and TurboPascal. Our file 1/0 driver also allows many other programs and languages to be used. E.g. DBASE, Clipper, COBOi, FORTRAN, MODULA-2 etc. SEPTEMBER 1992 25 a 32-bit, 37.5Mb/s bus with automatic this 640Kb limit, however. configuration. One potential drawback . Windows 3 and 3.1 take better adof the Macintosh NuBus is that, un- vantage of the hardware capabilities like other popular platforms, the sysof 80386 and 80486 computers. With tem does not include a DMA controlWindows 3, users have access up to ler for plug-in boards. Therefore, high16Mb of RAM and even more virtual performance NuBus boards may inmemory (the hard disk is used as exclude a DMA controller for high tra RAM) . However, Windows 3 has throughput. been criticised for its lack ofreal-time performance, mainly due to the slugThe performance of these I/O buses, especially the 32-bit buses, will be gish response of Windows to hardadequate for all but the most demand- ware interrupts. ing applications. The operating sysDespite this, high throughputs can tem and application software more be realised if the data acquisition often determines the ultimate success driver software and hardware takes of a data acquisition and control apthe necessary steps to work around plication. The operating systems com- the problem. First, problems can be monly used on PC/XT/AT/EISA and substantially reduced by using a virPS/2 computers are DOS and Wintual interrupt service device (VISRD) dows. that has quicker access to hardware interrupts. Second, the data acquisiDOS vs. Windows tion board should have large FIFO DOS has been standard for PCs for buffers on board to buffer data during several years and a huge supply of interrupt delays. software tools exists. Its real-time caThe third method uses alternating pabilities are sufficient for most data DMA channels. Data acquisition acquisition applications but the main boards typically use hardware interdrawback is that it limits the amount rupts to signal the CPU that the DMA of memory that can be used by an controller must be reprogrammed with application to 640Kb. Memory extend- the next memory segment. The DMA ers are available that help work around transfers halt as the controller waits to be reprogrammed. The problem is compounded in Windows because memory buffers in Enhanced mode can be heavily segmented into different physical memory locations. The DMA controller must be reprogrammed for each individual memory segment. With dual-channel DMA, however, the board automatically switches DMA channels at the end of a memory segment. DMA immediately begins on the second DMA channel while the interrupt is asserted and the CPU reprograms the first DMA channel for the following memory segment. This technique can be useful in DOS as well as in Windows. SC Acknowledgement Our thanks to Tony O'Donnell , of National Instruments Australia for this article, photos and diagrams. The Authors, Ash Razdan and David Potter, are senior staff members of National Instruments, at Austin, Texas, USA. ,-----------------, :Fax/Modem: The single handed I : I ":~~,o~ . 11 $349.00 I Send/Receive faxes from your PC I Your faxes can now be sent directly from your PC without having to print them first. You can view incoming faxes on-screen and print them using a standard dot matrix printer. Justthinkofthetime/papersavings . I I I I I I I I I I I : I , Extensive communication and fax software included. Versions for Windows and Macintosh also available. The Comma Corp. FaX/Modem is a TR29 Class 2 product. Class 2 is the current international standard for faX/modems, this type of equipment is faster and can operate in background mode. Class 2 FaX/Modems also look after difficult timing issues that leave your PC free for other tasks while your fax operates in background. For minimal effects on your PC choose Class 2. Mail Order Service $10.00 P&P per unit. m 1tt..CommaCorporabonP1y Lim,led PO Box 1100 Lane Cove NSW 2066 Level 1, 465 Pacific Hwy, Artarmon NSW 2064 Telep~~ne02-4186711 Facs1m1le 02-418 6713 , ~----------------SILICON CHIP I I I I The Comma Fax/Modem is a 9600 high speed send/receive fax and is also a full 2400 baud V22N22bis modem. This will allow you to communicate with other PC users or Bulletin boards just about anywhere around the world. Comma Corp. products carry an exclusive 15 month warranty. 1 li~iiiiiiii!iiil ~ 1 r:;- - --, ~ I I Mi I I I • ' · • ·· 26 I by Comma Corp. I I I I I I I I I I I I I data logger Gathering data with the Datataker 5 is so simple you can do it with one hand tied hehind your back. Programming, downloading and graphing the data is so simple you will only need one finger. Promise. The Datataker 5 can gather temperature, voltage or count information in any environment. The waterproof stainless steel housing is tough. So is the data store. 2000 readings absolutely secure in non volatile storage. Datataker 5 is ideal for monitoring food storage, machine downtime and energy consumption. In fact anywhere you need to record single channel of data. Datataker 5 has a replaceable internal battery that will power it for up to five years. For more information or a demonstration call: ~ Data Electronics 7 Seismic Court, Rowville Vic. ~ 3178.Tel: (03) 764 8600. Fax: (03) 764 8997. I ENQUIRY CARD II QUOTE 6211 I MELBOURNE . \ SYDNEY \ 3 Nicole Close, _ _,.__ _ _ _ _ _ _ _ _ _ _ _..,.____ t{orth Bayswater 3To37 Suite 1, Ram~at\ 2& 191 Ramsgate Road, P.O. Box 664, Bayswater 3153 Telephone: (03) 761 4466 \ Facsimile: (03) 761 4161 Toll Free: (008) 800 482 -----------.!'------- Sans Souci 2219 Telephone: (02) 529 227-7 Facsimile: (02) 529 5893\ • Capacitors • Connectors • Fans • Filters • Headers • LEDs • Plugs • Rectifiers • Relays Resistors • SCRs • Triacs • Sockets • Swtiches • Terminal Blocks • Varistors _ _ _ _ __ _ _ \ ~~~=~ l This new speed controller can be used with power tools rated up to 5 amps. Use it to control the speed of circular saws, electric drills, lawn edgers and other appliances with universal "brush type" motors. By LEO SIMPSON Heavy-Duty 5A Drill Speed Controller his new speed controller uses higher rated components to provide a higher current rating than similar circuits which have been around for quite a few years now. It will find many uses around the home and won't cost a bomb to put together. I've used a version of this circutt for years but I must admit I've rarely used it with my power tools. Where I have used it is with my electric lawn edger. This is a large unit and without the speed controller it is very noisy and breaks the Nylon line frequently. With the speed controller in use , the edger is much quieter and rarely breaks the line. No doubt, there are many other equally useful applications for a speed controller such as this since it gives a wide range of control with little tendency for "hunting" or "cogging". T How it works The circuit is well proven and one which many readers will be quite 28 SILICON CHIP familiar with except that in previous versions it would have used an SCR (silicon controlled rectifier) instead of a Triac, as shown here. In fact, for the purpose of understanding how the circuit works it is easier to think of the Triac as being an SCR. So now let's have a look at how a basic SCR speed control circuit works. Refer to Fig.1. This is just about the simplest speed control you can get. The SCR device conducts in one direction only and feeds half-wave rectified AC to the motor. Essentially, the SCR is a rectifier diode which only conducts when it receives a trigger voltage at its gate. Once it starts conducting, from anode (A) to cathode (K), it stays conducting until the load current drops to zero or the circuit voltage is reversed. Because the SCR is a switching device, it can be used as a very efficient power controller, and can vary large amounts of current while itself dissipating very little power. The circuit of Fig.1 controls the AC r l. A SCR 4.7 63VW 240VAC 1k MOTOR Fig.1: this basic circuit uses an SCR to feed half-wave rectified AC to the motor. The power fed to the motor is varied by triggering the SCR sooner or later during each positive half-cycle of the 240V AC waveform. power to the motor by triggering the SCR into conduction late or early in each positive half-cycle of the 240VAC waveform; the SCR does not conduct at all during the negative half cycles. If the SCR is turned on early in each AC half cycle, the power fed to the motor will be relatively high. Conversely, if the SCR is turned on late in each AC half cycle the power fed to the motor will be relatively low and hence the motor will run slowly. The trigger voltage for the SCR comes from VRl, a ZkQ potentiometer connected in series with a lOkQ resistor and diode Dl. This zkn potentiometer is fed with half-wave rectified AC which is partly smoothed by the 4. 7µF capacitor across it. The resulting ramp voltage from the wiper is fed to the gate of the SCR via diode DZ. F1 10A A 150k 1W SPEED VR1 10k LI N 02 1N4004 TRIAC1 BTA41600P Fig.2: the final circuit uses a silicon bilateral switch (SBSl) to trigger a Triac during the positive mains half cycles. This arrangement give a greater range of speed control than the circuit shown in Fig.1 & is more efficient. A2 240VAC SET MINIMUM SPEED VR2 5k 03 R250H 6A 01 1N4004 N Speed regulation Now you might ask: why use an SCR and allow conduction on only positive AC half cycles? Why not use a Triac which can be triggered into conduction on both positive and negative half cycles? The answer is that we could but then a fundamental advantage of this basic circuit would be lost. The advantage is speed regulation. A circuit with good speed regulation will maintain a selected motor speed regardless of variations in the load. If you are using a speed controller with an electric drill, you don't want the motor to bog down when you start to drill into the heavy stuff, do you? So how does the circuit give speed regulation? The answer is that the circuit monitors the back-EMF from the motor. Back-EMF can be defined as the voltage developed by a motor which opposes the supply voltage. The higher the speed of the motor, the higher the back-EMF. This circuit monitors the back-EMF in the following way. Notice that one side of the motor is connected directly to the SCR's cathode while the other side is connected to the cathode of diode Dl and to the mains Neutral wire. This means that the gate-to-cathode voltage applied to the SCR is the difference between the wiper voltage from VRl and the backEMF generated by the motor (disregard the voltage drop across DZ). Actually, in so-called universal motors (AC/DC series motors with commutators as used in most power tools and appliances), there are two back-EMFs generated. The first is a function of motor speed and the remnant magnetism of the field coils and is generated during the time when the SCR is not conducting; ie, during the negative half cycles of the AC waveform and during the first portion of VIE WED FROM BELOW .~ FRONT PANEL A2 SPEED CONTROLLER the positive half cycles before the SCR conducts. The second back-EMF is generated during the time when the SCR is conducting and since there will now be current flowing in the field coils (and also in the armature), this back-EMF will be higher than in the first case. However, we are only concerned with the back-EMF generated while the SCR is not conducting since it is this voltage which determines how late or early in each positive half cycle that the SCR begins conduction. Hence, the motor applies negative feedback to the gate of the SCR. This negative feedback enables the circuit to give good speed regulation. Say a particular motor speed is set by VRl and then the motor speed tends to drop because of an increase in loading. This reduces the motor back-EMF and therefore increases the voltage at the gate of the SCR. More correctly, it means that the ramp voltage at the SCR gate will exceed the voltage at the SCR cathode earlier in the positive half cycle and hence more power will be applied to the motor. This will tend to correct the drop in motor speed. Better circuit Now the basic circuit presented in Fig. l will actually work and was the basis of most speed control circuits used about 20 years ago. However, it has a number of drawbacks. First, the power dissipation through the lOkQ resistor is about 2.4 watts which means Warning! II This Speed Controller circuit operates directly from the 240VAC mains supply and therefore must be regarded as a potentially lethal project. If you are not confident about working on mains-powered projects we advise you to leave this one strictly alone. The wiring conforms to SAA standards and if constructed according to the instructions in this article, it is a safe appliance to use. Notes (1) The Speed Controller must only be used with universal "brush type" motors" with nameplate ratings of up to 5 amps. (2) Power tools should not be operated at low speeds for long periods otherwise they may overheat & suffer damage. (3) The Speed Controller must not be used with induction motors. (4) The Speed Controller must not be used to control the power to lamps or electric radiators. To do so would contravene regulations of the NSW Energy Authority and affiliated state energy authorities. SEPTEMBER1992 29 r-0 MAINS CORO " Fig.4: check your PC board for defects against this full-size pattern before mounting any of the parts. The board measures 72 x 52mm. Fig.3: take care with component orientation during the PCB assembly & be sure to use mains-rated wire for the connections to the mains socket (GPO). All adjustments to the circuit should be made with the power off. that it gets rather hot. Second, even though the current through the 10kQ resistor and VR1 is relatively high, it won't be enough for reliable triggering of higher power SCRs. And third, the circuit is not particularly good at very low speed settings. Silicon bilateral switch This is where the circuit of Fig.2 comes into the picture. You can see the similarities between it and Fig, 1. Instead of an SCR, we have used a Triac and instead of feeding the gate directly from VR1 as in Fig.1, a trigger circuit consisting of a silicon bilateral switch (SBS1) and a .047µF capacitor has been used. While the Triac is capable of conducting on both positive and negative half cycles of the 240VAC 50Hz waveform, this circuit only enables it to trigger on positive half cycles, because of the rectifier action of diode DL A silicon bilateral switch (SBS) is a voltage breakover device; ie, at voltages below its breakover point it is essentially open circuit but once the breakover voltage is reached, it becomes a low value of negative re- This CRO photograph shows the waveform applied to the motor when the Triac is triggered relatively early during the positive half of the mains waveform. 30 SILICON CHIP sistance. Don't worry too much about the "negative resistance" bit. All you have to remember is that it is used in conjunction with the .047µF capacitor. This charges up from VR1 via diode DZ until it reaches the breakover voltage of 8V (nominal). At this point, the SBS dumps the capacitor's charge into the Triac's gate and then it reverts to an open circuit whereupon the sequence can repeat itself during the next positive half cycle of the mains AC waveform. The energy stored in the capacitor is quite enough to trigger even insensitive Triacs and hence we are able to use a high power 40-amp device in this circuit. In this circuit, the motor back-EMF acts to reduce the charging voltage to the .047µF capacitor rather than reducing the SCR gate voltage as in Fig.1. But although the circuit arrangement Triggering the Triac later in the mains half cycle reduces the power delivered to the motor & hence it runs more slowly than in the previous example. You can now afford a sate IIite TV system For many years you have probably looked at satellite TV systems and thought "one day". You can now purchase the following K-band system from only: $995.00 Here's what you get: * The PC board is mounted on the back of the mains socket using 10mm metal spacers & secured using the socket mounting screws. Note the clamp that's used to secure the mains cord. is a little different, the speed regulation is just as good. The circuit efficiency is improved too, with only 200m W being dissipated in the 150kQ resistor which feeds VR1. This resistor has a rating of 1W to ensure that it has an adequate voltage rating. The functions of the three diodes in the circuit need to be explained. Diode D1 is there to reduce the power dissipation of the series resistor string and to ensure half-wave operation of the circuit. DZ is there to protect the gate of the Triac when it is in the conducting state - terminal A 1 can be above the potential of the gate. Diode D3 has been included as a flyback diode to quench the large inductive spike generated by the motor at the end of each positive half cycle. While the voltage spike does not cause any damage to the circuit, it does have the effect of disrupting the back-EMF monitoring system described above. VRZ, the 5kQ trimpot in series with VR1, is there to provide a minimum setting for the circuit. Why use a Triac? One question we have not answered so far is why we have specified a Triac instead of an equivalently rated SCR. The reason is quite simple. We did it to avoid the need for parts stockists to have to order in another device. We have specified a 600V 40A device so that it can withstand the "locked rotor" current of any power tool with a nameplate rating of up to 5A. Note that a "locked rotor" condition may well blow the 10A fuse but the 40A Triac should not be damaged. We have done this test! Another reason for using the 600V 40A Triac specified in the parts list is A 1.6-metre prime focus dish antenna, complete with all the mounting hardware. * One super low-noise LNB (1.4dB or better). * One Ku-band feedhorn and a magnetic signal polariser. * 30 metres of low-loss coaxial cable with a single pair control line. * lnfrared remote control satellite PARTS LIST 1 plastic case, 130 x 70 x 40mm 1 20-gauge steel front panel to suit case 1 PC board, code SC10109921 , 72 x 52mm 1 flush-mount AC socket 1 3-core mains flex with moulded 3-pin plug 1 cable clamp to suit mains cord 1 solder lug 2 M205 fuse clips 1 10A M205 fuse 2 10mm metal spacers 1 10kQ linear potentiometer (VR1) 1 knob to suit pot 1 5kQ trimpot (VR2) 1 150kQ 1W resistor 1 1kQ 0.25W or 0.5W resistor 1 .047µF 63VW MKT capacitor Semiconductors 1 BTA41-600P, Q6040J7 40A 600V Triac 1 2N4992 silicon bilateral switch (8B81) 2 1N4004 silicon diodes (D1 ,D2) 1 6A 400V silicon diode (D3) Miscellaneous Screws, nuts , lockwashers, solder. receiver with selectable IF & audio bandwidth, polarity & digital readout. Your receiver is pre-programmed to the popular AUSSAT transponders via the internal EEPROM memory. This unit is also suitable for Cband applications. Call, fax or write to: AV-COMM PTY LTD PO BOX 386, NORTHBRIDGE NSW 2063. Phone (02) 949 7417 Fax (02) 949 7095 All items are available separately. Ask about our C-band LNBs, NTSCto-PAL converters, video time date generators & Pay TV hardware. ----------- I YES GARRY, please send me more in- I I formation on K-band satellite systems. I II Name ... .... .... .............. ..... ............... .. I I I Address ············ ······· ············ ··· ········· I I I I ........................... P/code .............. .. I I : Phone .......... .. .. .... ........... .. .............. . I I ACN 002174478 01 192 I . ___________ . SEPTEMBER 1992 31 the steel front panel, along with the flush mount mains socket. ~ Mount the lOkQ potentiometer first, having cut its shaft to a length to suit the knob - 12mm should be about right. This done, fit the solder lug as shown, usFOR BRUSH ing a screw, nut and lockwasher. MOTORS UP This terminates the Earth wire TOSAMPS from the mains cord and also the Earth wire to the mains socket. The 240VAC mains cord enMIN ters through a grommeted hole in the case and is clamped to the steel lid using a suitable cable DRILL SPEED CONTROLLER clamp. The Active (brown) and Neutral (blue) wires are then Fig.5: this artwork can be used as a drilling template for the front panel. Be sure to stripped and soldered to their use a steel panel as specified - aluminium or plastic will not be strong enough. relevant points on the PC board. You will need to strip the outer that it is an isolated tab device. This flush-mount mains socket and is se- insulation of the mains cord back and means that it can be attached to a cured using the socket's mounting trim the wires so that the Earth (green/ heatsink without any need for a mica screws. Note that the holes for the yellow) wire is about 120mm long, washer or other means of insulation. Triac and the 6A diode should be while the Active and Neutral wires drilled to 1mm. are about 80mm long. Construction No special order needs to be folYou will need to run three insulowed when assembling the board (see lated wires from the potentiometer We built the prototype into a standard plastic case and have specified a Fig.3) but there are a few points to (VR1) to the PC board. These wires flush mount mains socket which is watch. First, the silicon bilateral should have 250VAC insulation and mounted on the lid. Since the stand- switch is a bipolar device so it can go should be about 100mm long. ard plastic or thin aluminium lid sup- into circuit either way around. SecTwo wires remain to be connected. plied with these cases would not be ond, do not bend the leads of the 6A These are the Active and Neutral wires strong enough with the necessary diode too close to the body - use a from the PC board to the flush-mount 35mm diameter cutout, we are speci- pair of pliers when doing this job. mains socket. Again, these must be fying a lid made of 20-gauge steel. Third, the leads of the Triac need to run in 250VAC insulated wire (strip This lid also provides the limited be cranked 90° at 5mm from the body some from the mains cord) and should amount of heatsinking required for so that the mounting tab lines up with be about 100mm long. the Triac. the adjacent mounting hole in the PC With all the wiring complete, you All the components with the ex- board. are ready to mount both the mains ception of the lOkQ potentiometer are socket and the PC board. Two 1/8Mounting the PC board mounted on a PC board measuring 72 inch brass screws 40mm long are rex 52mm (code SC10109921). This When assembly of the PC board is quired. These screws pass through board is mounted on the back of the complete, it needs to be mounted on both the socket and the 10mm spacers and retain the PC board with a nut and lockwasher each. In addition, one of the mounting screws also retains the tab of the Triac. This screw also provides the heatsinking path for the Triac to the front panel. This is why brass screws are specified in the parts list. After checking all the wiring carefully against the circuit (Fig.2) and wiring diagram (Fig.3) , the unit may be tested on the mains using a power tool such as an electric drill. Note that the unit must be disconnected from the AC mains when adjusting VRZ to set the minimum motor speed. Do not ever work on the unit while it is open and connected This side view shows how the mains socket & PCB are secured to the front panel to the AC mains - it is a potentially using 40mm screws and 10mm spacers. Note that brass screws are necessary to ensure adequate heatsinking for the Triac. lethal device. SC ::/lll!lilJ- MAX 32 SILICON CHIP __ )NICS J"IC:, )'iic:, J"JICS JNICS )NICS aAYCA II ,A\ CAR J A, CAH JA', CAR JA, CAR JA t. LEC Tl1 0N ICS ELt.Cl RON ICS bLI-CTRON ICS fLfCTRON ICS ELECl RO'-ICS JA\ C AR JAY CAR JA\CAH JAYCAR JA', CAR .. _ _ .• -· ELEC TR ONICS [Ll:Cl RONIC$ cLECTRON ICS FLFCTR01'ICS LLECTRONICS JA\ C AR JA\ CAR JAY CAR JA\CAR JA , CAR ~ .. ..,.. , . ...,, ELECTRONICS 1:Lf CTRONICS ELECTRONICS FLECTRONICS , l 1-CTRONICS ,, ...,.,. ........... v ,,,...., . • ,...,..,. ...,, . , '-' ' " ' , .. ._..,., , ,...., , .. -..,,._. .._.,,, '-'' " ' ,._._, ._, , , ,....,,.,._,_, v~, , ...., ,... ,, 1...1...L.._, , ,, v, ,, ..__,...., ., . . .,_.,. JAYCAR JAYCAR JAY CAR JA,CAR .IA\ CAR ELtCTR01'ICS F LI- CTRONICS EL, CTROMCS cLEcCTRON ICS Fl FC'TROMCS JAYCAR JAYCAR JA\CAR JA\ CAR ,JA\CAR [LlCTRO i'JI CS b LECTRON IC:, ELECTRON ICS ELECTRON ICS ELFCTRONICS JA\ C AR ,IA\ C AR JAYC1\R JA\ CAR JA, CAR CcLC TR ON ICS JAYC AH v""'' ....,,.,.,, L t LE C l I10NICS J AYCA R lLECTRO~ ICS JAYCAR r F cECTRON ICS JA, CAH bLECTHONICS ,JAYCAR FLECTRONICS JAYCAR E F LfC TRONICS JA', CAR HF Cl RONIC!:, JAYCAR cLECTRONICS JA\ CAR ELECl RO"JIC S JA, CAR ELFLlHONICS JAY CAR ELECTRONICS JA ,CAR F LFClRON lC,-, JA , CAR ELI-C'TRO'\IC'S JA\ CAR 1-LECTRO/\lCS JA, CAR . JA, CAH c F E 1- l.l C I HOf\ i.. ECTRQf\ JArCAf~ f.!A'rCAH f- _EC TR Ot, JAYCAR F "A',CAH ' ,, A'<CAR I- LFcrno, _Ecrno, , , , - - - --==-=-==--=-= =-:--,:-=-=-:==-~=-::= ,:--::c-=:-,~",--==:-:--=-::-:-,::-::,--=-:,-:,-::,-::'':"'-,,-,:;;;;;;;;;;;;;;;;;;;;;;;,;;;;;;;;;;;;;;;;;;;~;;;;;;;;;;;;;;;;;;;;;;;~;;;;;;;;;;;;;;;;;;;;====;:;;;;:: JA, CAR F JA, CAH , JA, CAR F JA\ CAf1 E _Ecrno,. That's correct, this is a high quality alarm system that is so cheap you can buy two, and keep one as aspare The company we bought these from has a new model out now, and they have asked us not to mention their name. We can tell you though, that they sell and install their own brand of burglar alarms and intercoms. The quality is unsurpassed and if your home hasn't a burglar alarmnow, then this is the time to buy one. -;~;::~~ THE ALARM EC 1RO, :~g;~g~ _1-c mo, _ECT Ro, cECTRO, ECTRO'_fcCTRO/\ ECTRON _EC TR ON ECT RO'J _ECTRON XCTRO"I _ECTl10N _ECTRON _ECTRON _ECTRON _ECTRON _FCTRO'FC TR ON EC l RON _[CTRON ECTRON _ECTROr-. _FCTRON ECTl10N _EC TR ON _EC TR ON EC TR ON _EC TR ON _E CTRON _ECTRON _ECTRON .ECTRO>< BRAND NEW HOME/OFFICE/WAREHOUSE ALARM AT LESS THAN HALF PRICE j~';g:~ ~ '17-~g7-~ ~ _IA' CAR E ~C~R E~~C~Ro~;cs ~A~CAR ~~~c~~o~;cs ~A~CAR~~~C~Ro~;cs ~A~CAR ~~~C~Ro~;cs ~A~CAR ~~~c~~o~;cs ~A~CAR ~L~C~Ro~;cs ~A~CAR ELECTRQ~;cs ~~~C~R FIFC~~o~;cs JAYCAR ELECTRO iCAt, f-LE'CTnON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS ,IAYCAR ELECTRONICS JAYCAR ELEC TR ONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR EL[CTflO ,CAR f-LFCTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTHONICS JAYCAR ELECTRONICS JAYCAH ELECTRONICS JAYCAH ELcCTHONICS JAYCAR ELFCTRO ,CAR E'LcCmONIC:o JA,CAR ELECTRONICS JAYCAR LLLCTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRO ICS JAYCAR ELECTflONICS JAYCAR cLECTRONICS JAYCAR f-LcCTHONICS JAYCAR ELECTRO ~CARLLLC ___ rCAR f-Ll.C -· - - - ----- · -- - - - --- - - - - - ·· - - • · · - · - - · - --~- - ., ,..., - • • • - · ~-• - - - ..... ,..,. . .. ,...,..., ,A,,,...A,.,._,,_,.._...,.,.,.,.... ,. ,,,....., ' "".,._ ,. ,..,,-,,,....Trv·, , 11r-c- l fl\lr-/\nr1c.r-,..nn~11r-c ;g:: ~~~g ;g:~ (~~g THE HUMAN SIDE Of COMPUTER BOOKS -all softcover 206 x 133mm ,CAR LLLC IC All Fu c Shows you how to: • Understand exactly whal DOS is, and why it's so important to know • Feel more at ease with your computer by understanding the basics of hardware and software• Use simple DOS commands• Learn basic file management and work wilh subdirectories • Customise DOS with CONFIG.SYS • Customise DOS with program files and batch files• And much more 220 pages Cal. BC-3040 ~Mf-~C /CAR t l cC . CAR CLEc· · cAri , u c ;g~~ ~~~g ,CAR ELEC , CAH FLEC C,\R f l F c g:~ ~~;6 CAR F Le c 1- L, c ·g~: ~~~g •c ,,R H Fe CAR f-l lkginnv.r'.s Guide to DOS CAR 1- L 1- CAf1 ELFC c,,n E11- c C AR 1- LI-C CAn ,LEC Shows you how to: • Use balch files to make your I·1Ie eas1·er • ut·1I·1se I1·ttle-known c,,R 1-Lf c C>\H 1-LI-C c,111 ELEC c. :g;;;; [:~g C,\R 1- _f-c CM, i JC .g:~ ;i:[ g , cAri , LEC , CAR 1-LEC , c ,\fl 1- 1 c rCi°l,,R fU-C c.-..11 , LI- c ('AH tlrC C AR, L[c 1 CAG: "-UC , C;\f"'\ f-Lf C iC,\ H ! LtC -C,\n f U-C :C,\ H f U-C HOW TO BUY AND UNDERSTAND COMPUTERS ~u-c fU:.C fll-C 1-LFC FI FC' f-1 F-C' Seerets HOW TO GET STARTED WITH MODEMS DOS commands • Maximise your PC's file-management capabilities• Use the DEBUG command to mod ify memory• Use the ANSI.SYS device driver to control your screen and keyboard • Use Greek letters for naming files from the keyboard • And hundreds of other useful DOS secrets 178 pages. Cat. BC-3042 Cat. BC-3046 $l 8 •95 Aouto-dial with your modem • rganise and back up your hard drive• And many more PC Secretsi. Includes Windows and DOS 5 o · 129 · tips. pages Cast. sc3048 CAR CAR CAR CAR C AH CAR 4Ah D Size NiCad Cat. SB-2462 $12.95 ea c,;n ru::c CAR f-U-C CAR FLFC' C.C..R Fl re· CAR f:LfC CAR CAR CAR CAH EccC cLLC 1-LcC :-U::C Cl,R Fl re CAR clcC. c.;R 'LI-C C MR :-L.:-( CAR t Lt C. C.AH t"U:C (.AH 1-U C CAR F li'C' CAR f cl-C CAH =. . . tC CAH f-l.J-(' CAR cLEC' CAR ElcC' CAR ELEC' CAR ELFC CAR Flf-C CAR ELEC' CAR HcC CAR ElcC· CAR ElcC CAR !cLEC' CAR ELcC' CAR ElcC· C AR ELEC' CAR ELEC' CAR EL.EC CAR ELEC. C AR ELEC. We've made a scoop purchase of IBM brand computer leads. These are high quality leads. The D25M to D25M has chrome plated backshells and thumbscrews and high quality Hitachi soft, flexible cable. The D25 to Centronics has achrome plated backshell for the 025 and an Amphenol Centronics plug, again with high quality Hitachi flexible, soft cable. WERE $23.95 D25M to D25M 9 pins connected (that's all your require) length 2.8m. $14.95 D25M to Centronics Cat. PL-0875 24 pins connected. Length 1.4m Cal. PL-0879 $14. 95 38Ah GEL BATTERY SALE Save a fortune over normal price. Size 197(L) x 165(D) 175(H)mm. Charge current 3.8 amps for 1O- 14 hours Discharge current 20 hour rate 1.9 amp. Oual ily Panasonic brand. Cal. SB-2495 Catalogue price $149.95 September Price $109.95 SAVE A MASSIVE $40 :,\H fl ~All 1.L :,\H 1-· :;AH l ... :::M~ 1:..L ~All l·.L :AR [ L :AH l L :;AR C--l . r,R Fl -:M~ ll :,'..f~ f l ~An tcl ':AR f L ·;Af1 l·L :::r\H rl ,/1.P [l :AR li Your computer is avaluable home and business tool. You rely on your computer for speed, efficiency, even entertainment. Your computer is, in fact, a vital investment of time and money. Surprisingly, however, few computer owners take the time to properly care for these expensive and delicate machines. Professional computer repair is often costly and time consuming. This book offers an understandable, inexpensive, and easy solution. AND you'll gain the knowledge and confidence needed to diagnose problems and perform your own repairs. 57 pages Cat. BC-3060 HIGH QUALITY IBM COMPUTER LEADS ... SIMPLE COMPUTER MAINTENANCE & REPAIRS re i-LFC fLfC f LI-C E:. .... t:C f-U-C 1-LI-C i ...;M~ t-~ '";Ar< f L ...,AH f l ~l\fl cl C~'..R ~UC CMR !""l k:__ ;AH' L ~~~ ~: :Ml u :AR cl ■-------------------------------------- ENHANCED XT/ AT COMPATIBLE KEYBOARD BARGAIN 101 keys See catalogue for ful l details Cal. XC-5090 ·•.·~ .,a• .,_·. ;.;,,_ .,;, $l . 8 95 $18.95 1CAP l"Lt"C ,CMR ,CAR CAR CAR C:AP Pc °'~'-- $18. 95 Shows you how to: • Buy the best model of modem for you • Install and set up a modem on your computer• Understand those confusing modem terms • Save money while on-line• Get communications software for free • Call electronic bulletin boards like an old pro • Start your own bulletin board system• Access your work computer from home 131 pages :~~ ~~ Shows you how to: • Understand, customise and maximise the power of Windows • Access commercial BBss like Prodigy and CompuServe• Install sound cards, memory cards, video cards, and more • Use unique DOS 5.0 functions like Doskey, Dosshell, UN DELETE & more • Use Memory Managers to better utlise RAM • Use batch files to quickly execute DOS commands • Alter your Path, so DOS can find your favourite fi les from anywhere on your hard drive • ,,..,,mh• Customise your AUTOEXEC.BAT ¥1:1xirMlbt"-" file to automatical ly load a favourite program • Troubleshoot monitor problems• Rejuvenate old printer ribbons • Shows you how to: • Read and understand a compuler ad • Find the hidden co st s behind buying acomputer• Evaluate different computer brands • Choose which printer is right for your needs • Avoid costly miS takes in buying computers• Und erst and computer terms and what !hey mean 198 pages Cal. BC-3044 ,CAR;LEC 1CAH ~~;;;: .~I. PC SECRETS $18. 95 1-c g~ ~~~~c DOS SECRETS ,Mi, LE EC'HO .AH I L BEGINNERS GUIDE TO DOS :g;~ :~;z, CAH 1/JVf"'I\QC:l!::CTRO $4. 95 :Ar, r·, :AR EL :AF< El :AR F, :AR EL :AR EL :AR cl :AR EL :AH E::1 :AR EL 'CAR ll :AR EL :AR El :AR EL ::AR c~ :Af1 El 'ARE, :AR El :AR El :AR FL :AR El :AR EL :An E :AR lcl :AR El :AR EL :AR E. Fl ~ARE, ::AR 2 COMPUTER/1 PRINTER AUTO SWITCH This is a non-power auto data switch designed for using one printer on lwo computers. No need to switch, does so automatically and uses no power. Time out 5-6 seconds, provides "Release" signal for the PC to avoid "Lock" problem when the other PC is printing. Suitable for IBM compatible systems. ,-.... Cat. XC-5088 /1 $69.95 \r.,; ........ I •~,,,, ---~l .,,,,,c "" 0 .. ., "~'------------ scoPE ..........~" / PROGRAMMABLE .... .., ALARM PANELS See catalogue for full details Some units may have slightly scratched Cat. LA-5180 front panel. 6 SECTOR PANEL Were selling for $399 Catalogue price $199.50 :ARE: ;ARE~ :AR EL :AR EL :AR EL :ARE! ~AR EL :AR El :AR El ;AA EL :AR EL :AR El ;AR [L ;AR EL ;AR EL ;AR El :AR El ;AR EL ~AR EL R F.L R EL R El R El , H EL .R EL R El j,R EL E'R El .' .R El ·,,R EL t ~A El 1R EL \R IR ,R ~R NOW ONLY $139 .50 - - - - - -.....-':....:;,;,,,.;;,;,,,.;..,,.,....;;_;,;,,,.;;2;_ ~= EL El El EL ~~ :TRor C AR fLfC.1t1 U 1-.J IL,~ J I-..Y'....,H H tlt-LI H V:',J!l,~ JAY, ·H t:Lt:L I H U I\J IC~ JJ...YCAH t.Lt:CIHUNIC~ JAYCAH t'Lt:CJHUN!C~ JAYl,A,H t.Ll::L I HUNIC~ JAYCAH 1::Lt:.CI H UNIC0 JA Yl,AH t.L t. L.; I HUN IL,~ JAYL,Arl t.Lt.CTRQ~ CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR FLECTRONICS JAYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC TRONICS.JAYCAR ELECTRON ICS JAYCAR ELECTROf CAR FLECTRONl CS JAYC AR ELECTRONICS JAYCAR fLEC TRO ICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRm CAR ELEC TRO NICS JAYCAR ELECTRONlCS JAYCAR ELECTRO ICS JAYCAR ELECTRONICS JAYCAR ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSIJAYCAR ELE CTRON ICS JAYCAR ELECTRm JICS JICS ,ICS ,ICS 1ICS •IC; .IAYCAR JA, CAR JA\ CAH JA ,CAR JA',CAR .IA'ICAR El fCTRONICS [t rCHlONICS f-Lf C I hOI\IC.~ FLFCTRONICS FLEC 1~ONICS [lf-C I HO~.ICS JAY CAR .,A, CAn 1A ,CAR JA, CAR JA, CAR .IA,CAR H FCTRON ICS I l rc1 RONIC.'i f Lf CTRONIC.S ELECTRONICS LLECTRONICS FLFCTRONICS .IAYCAR JAYCAR JA> CAR .JAYCAH JA rCAR .IA\ CAR FI f-ClHONICS EU CTRONICS f Lf ClRONICS I If CTRONICS ELl:CTRONICS FI f-CTRO NICS IAYCAR JA {CAR .JAY CAR JAYCAR JArCAR JA'rCAR f-LFCTRON ICS ELECTRQ,\JICS ELECl RO\JICS ELEC mONICS cLECTRONICS FI FrTRONICS JAYCAR JAYCAR JAYCAR .JA,CAf1 JAY CAR .JAY CAR 11 1:ClHONICS [L[CTf10NICS FLECTnONICS l:LECTRONICS ELFClHONICS FI f ClRONICs .JAYCAR JAYCAH JA,CAH JAY CAR JAY CAR JA,CAR f- 1 f-C TH ON ICS l LI Cll10N ICS f Lf ClRONICS ELI.CTRONICS U f-C THONICS F LI C1HOMC'-> JAYCAR JAY CAR .IAYCAR JAYCAn JA, CAH .JA, CAil I LFCTRONICS [LEC l RONICS FI f-Cl HONICS l:LFCTRONICS f-1 FCTRONICS f- If ('TRONI( S ,JAYC Afl JAYCAR JAYCAR JAYCAH JAYCAl1 .IA\ CAR FLEC f llONICS ELECTRONICS l Lf CinONIC'i t-Lf CTHONICS ELf-C TRONICS FLfcC ,ROWCS JAYCAl1 f L JA>' CAn I L JAYCAH lL .JAYCAH f-L .IAYCAR EL ,JAYCnH f L ,ICS JA · - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - · JAYCAf1 EL .ClHOI ,IA>CAH f-L JAT'CAl1 FI JAY(,AH LL UHO' JA\C.AHf-L ClflO" JA> (AREL :crnor JAY(.AH f L CTHOt ~Y( Al{ EL crnor \·,( Ar{ El crnor ,CAl1 LL ::;-p(Jt '<CAH EL crno, \CAfl f- L CTRQr YC/\H t t crnor .crno, LOW VOLTAGE NICAD BATTERY CHARGERS Two brand new economically priced low voltage NiCad chargers Exclusive to Jaycar ■ 9 VOLT FAST ■ 12 V DC DELUXE CHARGER COMPUTER BITS BY MIKE ZENERE A look at the 68705 microcontroller By using the right technology, lighting controllers, music synthesisers, keypad entry modules and burglar alarms can be custom designed with relative ease. Next month, we will feature a home burglar alarm based on the 68705P3 microcontroller, so let's take a look at what's inside this very versatile chip. The 68705P3 is a complete microcomputer on a chip. It contains CPU, EPROM, RAM, 20 pins of bidirectional I/O, a 15-bit interval timer and a clock. This circuitry is all contained in a 28pin package, with no external address or data buses. To make full use of the 68705P3's features, we have to understand its capabilities in both hardware and software terms. Fig.1 shows a block diagram of the MCU (Micro Control Unit). At the heart of the chip is the CPU (Central Processing Unit), which is made up of both a controller and an XTAL TIMER Prescaler ALU (Arithmetic Logic Unit). All executable instructions are decoded by the ALU under the direction of the controller. The 68705P3 has several types of memory, the first being 112 bytes of RAM (Random Access Memory). This may not seem like a large amount at first glance, but remember that this area is used to hold stack data and to keep track of variables. The second type of memory is ROM (Read Only Memory). This is not usable by the programmer under normal conditions but is implemented EXTAL Timer / 8 RESET INT Vpp Counter T1mer Control Accumul ator A 8 CPU Inde x Pon A 1/0 L,nes PAO PA1 PA2 PA3 PA4 PA5 PA6 PA7 8 Register Control Da ta 01 r Pon B Reg Reg X 5 Reg Regist er cc CPU Stack 5 Pointer SP Data OH Reg Progr am Cou nte r 1804 X 8 EPROM 115 X 8 8001s trap ROM The 68705P3 has 20 I/O (input/output) lines, all of which are programmable as inputs or outputs. These I/O lines are grouped into three ports: A, B and C. Ports A and B are both eight bits wide, while port C is only four bits wide. All three ports are TTL compatible and differ in the following way: port A lines, when in the input mode, float high due to internal pull-up resistors, whereas port B lines are capable of sinking l0mA of current. This means that LEDs may be driven directly from port B. · Along with each port is an associated DDR (Data Direction Register). The DDR operates under program control and is used to tell the port whether its associated bits are inputs or outputs. The clocking source for the processor is quite versatile, and there are four options available. Fig.2(a) shows how the unit can be PB0 clocked by an external PB1 Pon P82 source, while Fig.2(b) 8 PB3 1/ 0 PB4 shows how · the clock frePB5 Lines Code Dat a Q ,r Input/output PB6 PB? Condition Port A Reg when the program needs to be burnt into the on-board EPROM (Erasable Programmable Read Only Memory). The 1804 bytes of EPROM are used to hold the program on a permanent basis so that even if power is removed, the program is not lost. 3 High PCH Port C Reg ALU Program Coun1er 8 Low PCL 112 X B RAM PC0 PC1 PC2 PC3 Port C 1/ 0 Lines Fig.I: block diagram of the 68705P3 microcontroller. It contains a CPU, 1804 bytes of EPROM, 112 bytes of RAM & 20 programmable I/O lines. SEPTEMBER1992 37 ,rno,17 •r___n . : . . CLOC; u , --l__J c[],. .fi] (c) 27Pf~ .,. (d) Fig.2: the unit can be clocked by an external source (a) or by an on-board oscillator. The on-board oscillator frequency can be set by an external resistor (b); by a link (c); or can be crystal controlled (d). qu en cy can be set by an external resistor. Fig 2(c) shows how the on-board oscillator is selected. Finally, Fig.2 (d) shows how a crystal is applied between pins 4 & 5 to obtain an accurate clock signal. Returning to Fig.1 again, we can see that the processor can be interrupted through the INT input. Normally, th e processor executes a desired program but, under certain circumstances, it may be required to halt normal operations and temporarily run a different program. This interrupt line is also quite flexible and is able to accept both analog and digital signals. This is accomplished by a Schmitt trigger which can detect the zero crossing points of an AC signal. PROGRiM COUNTER Other interrupts STACK POINTER There are two other ways of interrupting the processor: (1) by using a software interrupt instruction; and (2) by using an interrupt generated by the count out of the on-board interval timer. The interval timer and its optional prescaler are software selectable. Once the counter is loaded, it starts to decrement at the rate of the internal clock. When it reaches zero, an interrupt is generated which the processor may or may not acknowledge, depending upon the setting of internal flags. The prescaler is a 7-bit divider and is used to extend the count of the timer. Resetting of the processor can be accomplished in two ways. First, a lµF capacitor is connected from its RESET pin (pin 28) to ground. This provides sufficient time at power up for the oscillator to stabilise. The second way is to apply a digital (logic 1°1°1°1°1 1 1•1•1•1•1•1 1 1 CONDITION CODE REGISTER HALF-CARRY INTERRUPT MASK NEGATIVE-----' ZERO-----' CARRY------' Fig.3: this diagram shows the 68705 programming model, with the condition code register at .the bottom of the list. This register keeps track of certain operations and is acted upon during the course of the program. low) signal to the RESET line from an external circuit. Software overview The instruction set for the 68705 series of processors is well suited for bit manipulation and testing. Both the HITACHI COMPACT SERIES SCOPES C RT READOUT AND CURSOR SCOPES CRT READOUT SCOPES V-1065A DC to 100MHz V-665A DC to 60MHz V-1060 DC to 100MHz V-660 DC to 60MHz Dual c hannel, delayed sweep, CRT readout, cursor readout (not prov ided on t he V- 1060 and V- 660), frequency counter (not prov ided on the V- 1060 and V-660), sweep tim e autorang in g, trigger lock. Hi tachi Compact features CRT Readout, Sweep Ti me A uto rang in g and Trigge r Lock Functio ns. 'II ST LUCIA ELECTRONICS 'II 24 Campbell St. Bowen Hills V212 AT $719 + TAX (V212 NOT SHOWN) AND "FLUKE" SCOPE METER'S FROM $1459 + TAX. <at> HITACHI 38 S ILI CON CHIP Q 4006. Tel: (07) 252 7466 Fax (07) 252 2862 ECONOMIC ELECTRON/CS: 22 Campbell St. Bowen"Hills Q 4006. P.O. Box 481, Fortitude Valley 4006. Tel: /07) 252 3762. Fax /07) 252 5778. SOUTHPORT ELECTRONIC SHOP: Shop 1, 10 Welch St. Southport Q 4215. Tel: /075) 32 3632. Fax: /075) 51 0543. accumulator and the index registers are eight bits wide, while the program counter is 11 bits wide. This gives the MCU a total address range of 2048 locations. This number includes all ROM, RAM, EPROM, 1/0 ports and DDRs. The stack pointer is also 11 bits wide but is only capable of obtaining_ a depth of 32 bytes as the top 6 bits are fixed. This might seem like a small number but is sufficient for most applications. TABLE 1: 68705 MEMORY $000 Port A $001 Port B $002 Port C (low order nibble only) $003 Not used $004 Data direction register, Port A $005 Data direction register, Port B $006 Data direction register, Port C (low order nibble only) $007 Not used Programming model $008 Timer data register Fig.3 shows the 68705 programming model with the condition code register at the bottom of the list. This register keeps track of certain operations and is acted upon during the course of the program. The first bit informs us if a CARRY has resulted from adding two BCD (Binary Coded Decimal) numbers. The second bit lets us tell the CPU to ignore any interrupts. The third bit tells us if a negative number was stored in the accumulator, while the fourth bit tells us if the value of the accumulator was 0. Finally, the fifth bit informs us if a CARRY was required for the last operation. The entire memory map is shown in Table 1. Notice how all of the RAM, 1/0 ports, timer registers and DDRs reside in page 0, while the EPROM starts in page 1. At the end of memory, there are four vectors and each has its own individual use. These four vectors are: (1) RESET - when power is first applied. (2) INT - when there is a change of state on pin 2. (3) SWI-when the instruction SWI (software interrupt) is encountered in the program. (4) TIV ~ when the internal timer times out. When any of the above four conditions are met, the processor loads its program counter with the data contained in the two locations associated with that interrupt and continues execution from that point. $009 Timer control register $00A Not used $00B Program control register $DOC - $00F Not used $010- $07F RAM $080 -$783 EPROM $784 Mask options register $785- $7F7 Bootstrap ROM (EPROM burner program) $7F8-$7F9 Timer interrupt vector $7FA- $7FB External interrupt vector $7FC-$7FD SWI interrupt vector $?FE - $?FF Reset vector Address modes There is a total of 10 address modes that the 68705P3 can use. Because the range is rather extensive we will only look at a few of the more commonly used ones. Immediate: the first one we come across is the immediate addressing mode, which deals with constants. For example, LDA 30 loads the accumulator with the value 30. Direct: the direct addressing mode is used to load variables rather than constants. Therefore, LDA 30 instructs the processor to load the accumulator with the contents of location 30. In this mode, only page zero is accessible as the effective address is specified by a single byte. Extended: the extended addressing mode is similar to the direct addressing mode except that two bytes are used to form the effective address. Thus , LDA 700 instructs the processor to load the accumulator with the contents of location 700. The disadvantage with this is that execution time is slower and the instruction takes up an extra byte of memory. Inherent: in this addressing mode, there is no effective address. These instructions are used when all of the required information is already in the CPU. As an example, the instruction CLR X would load the index register with all zeros; ie, it would be cleared. Indexed: there are three types of indexed addressing modes accessible to the programmer. (1) Type a: indexed - no offset. The instruction LDA,X instructs the processor to load the accumulator with the contents of the address pointed to by the index register. (2) Type b: indexed - 8-bit offset. With this instruction, the contents of the index register are added to the 8bit offset to give a final address from which the data is manipulated; eg, LDA 40,X. (3) Type c: indexed - 16-bit offset. This 2-byte indexed form of addressing allows complete coverage of the entire address range. For example , the instruction LDA 700,X results in the number 700 being added to the contents of the index register, and then the accumulator is loaded from this final location. Bit manipulation & testing The instruction set for the 68705 series of chips has all of the usual commands as well as some very powerful and interesting bit instructions. The first two we are going to look at are Bit Set and Bit Clear. For example, BSET 3,DRA sets bit 3 . of data register A to logic 1, while BCLR 7,7F sets bit 7 of RAM location 7F to logic 0. The next two unique instructions are Branch If Bit Set and Branch If Bit Clear. Both of these instructions test the designated bit and branch accordingly. For example, BRSET 7,60,20 is decoded as "test bit 7 of location 60 and if set then branch forward 20 locations and continue program execution there". Programming Once the designer has decided on the type of application, the software can be written. Because most people have a PC, a fast and accurate way to produce the necessary code is to use a cross assembler. Basically, this is a language translator which runs on a computer and converts normal ASCII code into a language that the 68705 will understand. The next step is to download this information (hex code) into a 2716 EPROM. Once this has been done , the data is then transferred byte by byte into the EPROM aboard the microcontroller using a 68705 programmer board. SC SEPTEMBER 1992 39 VINTAGE RADIO By JOHN HILL Repairing an old Heathkit radio frequency generator A radio frequency (RF) generator is an invaluable test instrument when it comes to aligning and adjusting old radio receivers. But why buy new when you can often refurbish an old unit for just a few dollars? In the early days of my vintage radio activities , a receiver tune-up was a bit of a hit and miss affair. If an adjustment screw was turned and there was an improvement, well and good. If nothing much happened, then it was best left alone. Everyone has to start somewhere and I started at the bottom of the ladder knowing very little. This radio frequency generator was restored to "as new" condition. It is a Heathkit RF-1 of 1960s vintage and was originally marketed in kit form. 40 SILICON CHIP Naturally, I never had any alignment instruments in those days (apart from a screwdriver) and lacked such niceties as a radio frequency (RF) generator and output meter. These tools of trade make alignment quicker, easier and far more accurate. I am not saying that a reasonable alignment job cannot be done without these instruments but, from my point of view, I would much sooner use them than not use them. If a receiver is badly out of alignment, the right equipment makes a big differ- ence to the successful outcome of the job. My first radio frequency generator was bought new from one of our local electronics retailers. But although it looked pretty on the outside, this "hitech" Taiwanese instrument was not all that good on the inside, and exhibited a very strange fault. If a frequency of 600kHz was fed into a radio receiver, there were two adjacent resonance points, one nominally on 600kHz and another a little lower on the dial. When tuning the radio dial, the effect was to tune onto the signal, off the signal, then back onto it again. Which was the right signal was a bit hard to judge. When a second generator of the same make exhibited similar characteristics , it seemed like the right time to ask for a refund - and I did! Per- The top of the chassis is neatly laid out and carries the two valves. The Heathkit RF-1 operates from a 110V supply (note the small power transformer) and must be used in conjunction with a 240-ll0V step-down transformer. TABLE 1 Band Frequency Range A 100 - 320kHz B 310 - 1100kHz C 1 - 3.2MHz D 3.1 - 11MHz E 10- 32MHz F 32 - 110MHz Band F is also calibrated for 2nd harmonics up to 220MHz The under-chassis wiring is not so neat and is a typical rat's nest of point-topoint wiring. The two capacitors at top are polyester replacements for the troublesome paper types originally used. The RF-1 uses two valves: a 6AN8 and a 12AT7. Although the originals tested OK, they were replaced as part of the restoration procedure. haps it was a bad batch? Maybe it was only a simple adjustment? All I know is that I was relieved to have my money back. Heathkit generator One week later, I had the opportunity to buy a Heathkit RF-1. Normally supplied as a do-it-yourself kit, this particular unit had been put together some time in the 1960s and was still working quite well. The Heathkit RF-1 is a valve type generator, not solid state. The valves used are the 6AN8 and 12AT7, both relatively modern types and still readily available. There was no double spotting with this unit; the RF-1 worked perfectly. It has a frequency range from 100kHz to 110MHz (220MHz in harmonic mode), which makes it a little more versatile than some earlier generators. The good bit, however, was the price. At just $10.00, I felt as though I had stolen it! Using a radio frequency generator and an output meter makes receiver alignment a breeze but, just recently, the old RF -1 developed an annoying fault. Often, usually in the middle of a tune-up, the output would dip to quite a low level. Such a malfunction is disconcerting to say the least, because one is never sure whether it is the generator or the receiver that is at fault. An "out of sight out of mind" attitude prevailed for quite some time. I only ever thought about the problem when it played up while I was using it. Suddenly, I made up my mind to do something about it and within minutes the generator was in pieces on the workbench. Everything looked OK, although there were a few old-style paper capacitors in the circuit that I considered suspect. If these can give trouble in a radio, then why shouldn't they also cause problems in an RF generator? There were four paper capacitors and they were replaced with high voltage polyester types of the same value. Next on the list were the switches. The old Heathkit generator has several multi-pole switches and these were sprayed with electrical contact cleaner, and the contacts checked for adequate tension. It requires only one faulty switch contact for all manner of problems to arise. The switch check was followed by an exa{Ilination of every solder joint in the circuit. One has to remember that, in this instance, the generator was a home assembly job and although it was put together by a competent technician, we are all capable of a crook solder joint now and then. Checking the joints with a magnifying glass revealed that there were a few suspect ones and three joints were SEPTEMBER1992 41 erator is approximately 30 years old, the new values and capacitors must make the unit more reliable. It will probably still be working long after I have departed this planet. Calibration woes This 2-gang tuning capacitor is connected to the dial on the front panel. Note the 5-turn airwound coil attached to the rear end of gang. This is the "band F" coil mentioned in the story. This view shows the band selector switch and the various oscillator coils. The inductance of each coil can be varied by adjusting the iron slug inside the coil former. resoldered just in case. This was probably unnecessary but the generator did have a problem and I was determined to eliminate it. Valve checks An instrument such as a radio fre quency generator does not get a great deal of use and is not the sort of thing that is hard on valves. Even though the valves tested OK, both were replaced as the necessary types were conveniently on hand. If the generator was going to be properly repaired, then two new valves would not go astray. 42 SILICON CHIP Finally, a nuts and bolts check, and it was this operation that located the probable cause of the trouble. One of the tag strips bolted to the chassis was quite loose. It had been only finger tight ever since the kit was first put together. The centre tag that bolts to the chassis is also a chassis connection for three other components. It was tightened accordingly and other chassis connections also checked. It appeared as though I had carried out the repair in the wrong order. If I had started with the nuts and bolts check it may have saved some time. However, considering that the gen- Replacing the valves and capacitors is one thing: their effect on the frequencies produced could be another matter. The final stage of this RF generator repair was to calibrate each band so that the generator would produce the frequencies indicated by the dial. One might expect that such as task can only be performed with the aid of some expensive laboratory equipment but this is not the case. The alignment can be checked simply by using a radio receiver. Because the calibration involves LW, MW, SW and FM bands, I found it necessary to use three different receivers. Table 1 shows the frequency ranges of the RF-1 's six bands. Most of these bands can be checked in several positions simply by comparing the reading of the generator dial with a radio station of known frequency. In the case of shortwave stations, this may be easier said than done if one is not familiar with their callsigns and frequencies. The generator does not have to be connected to the receiver; simply placing the output leads in close proximity to the set provides sufficient signal coupling. Tuning slugs are provided in the oscillator coils which, traditionally, are adjusted near the low frequency end of each band. However, the instruction manual implies that this should not be necessary as the coil assembly is pre-tuned at the factory. Alternatively, it should only be undertaken if adequate equipment and experience is available. Adjustment at the high frequency end is normally by means of trimmer capacitors, one for each band. In this case, with the coil and switch assembly pre-tuned, the makers have seen fit to reduce this to a single trimmer. This is connected to the grid of the oscillator valve, making it common to all bands, and is probably provided to take care of the external distributed capacitance (eg, the capacitance of the wiring, and the internal capacitance of the oscillator valve). Significantly, the instructions say that this trimmer should be adjusted at the high RESURRECTiON RADIO Vintage Wireless Specialists This nifty little radio receiver with its digital dial solved all of the problems associated with the realignment of the generator. frequency end of one of the bands. Initially, band A on the Heathkit RF-1 was checked on the long-wave band (150-350kHz) and this revealed considerable discrepancies between the readout on the generator's dial and the dial setting on the receiver. Unfortunately, nothing much could be done regarding the alignment of this band until the frequencies of some LW transmissions were known. Band B was checked on the AM broadcast band using a station of known frequency below 1 lO0kHz. I used 3AR on 62 lkHz as a reference. Band C was also checked using the AM broadcast band and a station of Table 2 Freq. (MHz) Station Location VNG Australia WWVH Hawaii wwv USA 5, 10, 15,20 CHU Canada 3.330, 7.335, 14.670 JJY Japan 5, 8, 10, 15 AWN Russia 4.996, 9.996, 14.996 RID Russia 5.004, 10.004, 15.004 5, 8.638, 12.984, 16 5, 10, 15 These standard time & frequency stations provide useful reference points for signal generator calibrations. Note that some Russian signals are in CW only & need a BFO to be resolved. known frequency above 1MHz. In this case, I used 3XY on 1422kHz. Bands D and E can be checked using shortwave stations if one is sure of the station frequency. But because I don't know the frequency of even one shortwave station, I found myself facing the same problem as with band A. As before, comparing the generator's dial with receiver dial calibrations showed considerable discrepancies. It is also interesting to note that although the receivers were modern transistor types that had not been tampered with, their shortwave dial calibrations were only approximate. Band F was easy to check. By using a local FM station, 3CCC on 103.9 MHz, the generator was found to be not quite on frequency and a small adjustment was required to correct the error. The band F coil has no coil slug adjustment. Adjustment is by simply squeezing or stretching the coil in or out. After all this checking, the alignment process had been only partly successful; there were still three bands that required checking and possible adjustment. One colleague suggested using harmonics from the generator as a calibration aid. For example, assuming that bands B and C had been adequately calibrated against broadcast stations, a signal generated on band A would produce second and third harmonics which would land in one of these two bands. Similarly, signals generated on the broadcast band would produce harmonics in the shortwave bands. However, at this stage, I received Repairs - Restoration - Sales Our skilled technicians offer QUALITY repairs and restoration. We also have a large stock of bakelite and timber radios fully restored and for SALE. Parts are available for the enthusiast, including over 900 valve types, high voltage capacitors, transformers, dial glasses, knobs, grille cloth etc. Circuit diagrams for most Australian makes and models. Send SAE for our catalog. WANTED: Valves, Radios, etc. Purchased for CASH Call in to our showroom at: 51 Chapel Street (PO Box 1116), Windsor, Vic 3181. Phone: (03) 529 5639; Fax (03) 510 4486 help from an unexpected quarter. David, a young vintage radio collector friend, lent me a radio that solved all my problems. David's receiver is one of those new-fangled types that has a digital frequency display. Almost any mongrel frequency can be keyed in and that is precisely what you get. Wow! Did this little receiver make bands A, D and E easy to adjust. It's marvellous what the right equipment can do! When finally aligned, the RF-l's accuracy was well within its specified ±2%. It would be most interesting to compare this old valve type generator with a modern solid state unit. I am quite sure that it could hold its own in any company. My repairs to the old Heathkit signal generator proved to be completely satisfactory and there were no more malfunctions. The generator is perfectly stable, remarkably free from harmonics, and completely accurate at the frequencies at which it is used. However, the new valves and capacitors have pushed the price up to around $20.00. Shame about that! 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SD PURE CLASS A POWER AMPLIFIER ELECTRONIC KITS & MODULES Build the Interphone: a 10-station exchange for your home; Pt.2 In this final article on the Interphone, we give the assembly details and the installation procedure. Depending one how many remote station boards you build, you can connect up to 10 tone dialling phones to the system. By JEFF MONEGAL The construction of the PC boards for this project requires no special care or attention , just a fine soldering iron tip and some patience. Start by going over the PC boards, looking for problems such as shorted tracks or fine breaks in the copper pattern. Any faults fixed now will save a lot of time later. How many phones do you want to be able to connect? The standard remote station board will accommodate up to three phones so if you make two remote station boards, you can have six phones; if you build three remote station boards you can have nine phones. If you want the full 10 phones that the system is capable of, you will need to build a single station board in addition to three standard remote station boards. When it comes to building the remote station boards, we suggest you build just one standard 3-station board first. That way, if you do find problems, they will have been corrected by the time you come to build the other boards. ERPHClNE A large plastic case accommodates virtually all of the circuitry, including the base station board & the remote station boards. A buzzer & a Busy LED are also installed at each extension & wired to a standard telephone socket. 46 STLICON CHTP We also suggest that you complete each board before starting on the next. Our prototype used IC sockets but these can be regarded as optional. They do provide an advantage if you have to troubleshoot the circuitry later. Let's start with the base station board. The wiring diagram is shown in Fig.3. Make and insert all the wire links first and then install the smaller components such as resistors, diodes and small capacitors. Next, install the electrolytic capacitors and integrated circuits, paying particular attention to the orientation of the ICs which will be damaged if they are incorrectly installed. The same comment applies to the installation of the 3terminal regulator and the transistors. Complete the base station PC board assembly by inserting all the remaining components such as the isolation transformer, 12V relays and the crystal. Our prototype boards also used PC-mount screw terminal blocks which are handy for making all the off-board terminations . Note that three insulated wire links must be installed on the copper side of the board - ie, from A to A, B to B and C to C. With the base station board complete, go over your work carefully, comparing it to the wiring and circuit diagrams. This done, you can turn your attention to the remote station board. The wiring diagram for the 3station board is shown in Fig.4. Don't forget that each remote station unit has to be programmed with an identification number before final installation. Each station should use a different output link option from IC10 so that when any extension is paged from another, only one extension will respond. Remote station 1 (ie, extension 1) should have a link from the cathode of diode DZZ to pin 14 ofICl0. Station 2 should have the Fig.3: make sure that all parts are correctly oriented when building the base station board. Note that three wiring points marked A, B & C must be linked to three similarly marked wiring points using insulated wire on the track side of the board (ie, A-A, B-B & C-C). Fig.4 (right): this is the parts overlay for the remote station board. Each remote board accommodates up to three stations & you can build a maximum of 10 stations. Note that each station must use a different output link from IClO - see Table 1. link from D22 to pin 2 ofIClO. Station 3's link would go to pin 15 of IClO and so on up to a maximum of 10 station units. The full list of remote station links (from IClO) is shown in Table 1. Each remote station board should be labelled to show which extension number it is coded for. This will simplify the installation procedure. Case wiring When all the PC boards are fully assembled, the next stage is to install them in the case and complete all the wiring. Our prototype used a large instrument case which accommodates all the PC boards with space to spare. Our prototype also had the boards Table 1: Remote Station Links Extension IC10 Pin No. 0 Pin 3 1 Pin 14 2 Pin 2 3 Pin 15 4 Pin 1 5 Pin 6 6 7 Pin 7 ! Pin 4 8 Pin 9 9 Pin 5 mounted on a baseplate made of PC board material as can be seen in the photos. However, this was a carryover from an earlier version and is not really necessary; you can mount the boards directly into the case. The base station is mounted by itself on the lefthand side of the case while the remote station boards are stacked on each other, on the righthand side of the case. Our prototype was wired using conventional 4-core telephone cable and with standard Telecom-style phone sockets on the rear of the case. However, the wiring itself is not standard. The wiring of the various pins in the sockets is as shown in Table 2. As you can see, pins 2 and 6 are SEPTEMBER1992 47 ,. This view shows how the boards are mounted inside the case. The base station is on the left, while the remote station boards are stacked on each other to the right. Note that the base station board was modified after this photo was taken. used for the internal line connections and so are compatible with any standard DTMF (tone) phone. You can now complete the wiring inside the case. This includes the wiring to the front panel LEDs, the AC plugpack socket and the incoming phone line plug. System testing The first step is to check the DC supplies generated by the circuit. Connect a 12VAC plugpack and use a multimeter to check the +50V and +5V supplies on both the base station and remote station PC boards. Check for the presence of +5V at the supply pin of each IC and also at the collectors of transistors Q4 and Q5. Check for the presence of +50V at pin 6 of each extension socket and also at the collector of Q7, the buzzer driver on each remote station board. Now put the whole system aside and begin modifying the extension 48 SILICON CHIP handsets you will be using. Each one will require the addition of a buzzer and a red LED (Busy LED). Depending on the type of handsets you are going to use, the buzzer and Busy LED may be installed in the base, the cradle or, if it is a one-piece phone, in the receiver itself. One side of the buzzer and the negative connection (K) of the red Busy LED connect to the GND line (pin 2 of the extension socket). The other side Table 2: Socket Connections Pin 1 No Connection Pin 2 GND Pin 3 Busy LEDs Pin 4 No Connection Pin 5 Buzzer Pin 6 Phone Line I, .. of the buzzer connects to the buzzer line (pin 5 of the extension socket), while the positive side of the Busy LED connects to pin 3 of the socket. When your tone phones are suitably modified, you are ready to connect and test the complete system. Connect at least two extension phones to the system and apply power. Lift the handset and the Busy LEDs should start flashing. Now press the# button. The Line LED should light. Hang up the handset and both the Busy and Line LEDs should go out. Pick up the phone again and press the * button and the Hold LED should light. Now press the# button and the Hold LED should go out again while the Line LED goes back on. Press the * button and the Hold LED should light and stay alight when the phone is hung up. After about 30 seconds, the buzzer will sound, warning you that a call is still on hold. At this stage, you have tested most of the functions of the base station. Now try calling another extension. Pick up a phone and press the wanted The rear panel of the case carries standard telephone sockets for the connections to the extension telephones, plus a power socket for the plugpack supply. The two sockets at lower left are not used in the final version. number of another extension for at least two seconds. The ringer in the wanted extension should then sound for as long as you hold down the number button. If you now pick up the other phone, you can have a 2way conversation on two phones between yourself and yourself - great if you are a split personality! Better still, get a friend to pick up the other phone and talk to him or her instead. You can now connect as many handsets as desired and repeat the tests to make sure that all is well. Finally, you are ready to connect the incoming phone line. The Interphone is connected in parallel with an existing tone phone. Now pick up an extension phone and press the # button. You should now hear a dial tone in the earpiece. Dial a number to confirm that all is correct. To hang up, you simply replace the handset. Pick up the phone again and press the # button. Dial a friend and wait until you hear them talking. Inform them as to what you are doing and that they should not hang up the phone. Press the * button, then wait a few seconds then press the # button again. Your friend should still be on the WARNING! In order to comply with the Telecommunications Act, we dri3-w the reader's attention to the following: "This customer equipment has no AUSTEL permit and mat be dangerous or damage a telecommunications network. Connection to a telecommunications network is an offence under section 253 of the Telecommunications Act 1991 and may attract a maximum fine of $12,000". line and you should be able to talk as normal. Now check that you can transfer you call to another extension phone using the # button and the appropriate number button. If all is well, the Interphone is working as it should. You can now run 4-core wiring and wire phone sockets to each point in your home requiring an extension. Once this has been completed, power the whole system up again and go through the functions again to ensure that all is working properly. Kit availability At the time of writing, the copyright for this project has been sold to Altronics of Perth. They should have kits available shortly after this issue goes on sale. Readers should contact Altronics for details of kit prices. The author and designer of the Interphone project will be offering a repair service for readers who need it. He can be contacted at PO Box 33, Condell Park, NSW 2200. Phone (02) 708 3763. SC SEPTEMBER1992 49 Build it yourself with a flllJl!5-. 6ATTER YV-OlTAGE 6r12V SLA BATTERY CHARGEA For Sealed Lead Acid Batteries SLA BATTERY CHARGER Charge your gel cells safely and correctly with this easy to construct 'intelligent' battery charger. Incorrect charging usually damages the battery's internal structure. considerably reducing its service life. This unit monitors the battery and automatically maintains a constant 'float vol tage'. In fact, you can even attach it permanently to the battery. It charges both 6V and 12V batteries and automatically adjusts the charging rate to suit the battery . With a 6-way rotary switch for current settings, 3 LED's which indicate charging modes and a shortcircuit-proof safety feature. Complete with delu xe case, PCB , all components, pre-punched silkscreened front panel and metal rear panel, power transformer and current meter. s..fJli:1!..~ ~ Cat K-3204 g"fL ' AUG '92 $129 PULSE GENERATOR KIT A sensational pulse generator kit which costs far less than comparable models. Ideal for evaluating wideband amplifiers and filters, adjusting frequency compensation in scope probes and working with digital circuits . With a frequency range of 1Hz to 1MHz, single-shot, adjustable pulse w idth from 350ns to 100ms and adjustable delay on the main output. What's more, it has variable output pulses from 1V to 10V, a choice of either positive or negative output polarity, selectable AC/DC coupling and it's mains powered. A full form kit with all components, hardware, pre-punched screened front panel and a delu xe s999s case. Cat K-7342 ELECTRONIC DOORBELL A quality doorbell system that looks so professional, you'll have a hard time convinc ing friends that you built it yourself. What's more , unlike other doorbells all components are fu lly replaceable so it's super easy to service and repair. A full form kit with all components, hardware, doorbell switch , battery holder, cab le and a stylish deluxe doorbell case. Requires 4 x 'AA' batteries. Cat K-3800 s229s INFRARED LIGHT BEAM RELAY ~---.iH l:i!L~ g5,'jj DEC Ideal as a doorminder or to monitor areas around the home or shop. This simple project• triggers a one second alarm when someone wa lks through its beam. You can connect it to a buzzer or trigger relay depending on the application. It's a full form kit with all components, PCB, case, front panel label, plug pack and relay for greater flexibility. Cat K-3120 '91 BARGAIN PRICED COMPONENTS LIGHTNING SURGE PROTECTOR This quality 3-electrode , gas fil led arrester significantly reduces the effect of high voltage discharges (such as lightn ing) on telephone equipment. An Austel Certified Component (A90/M E/ 0041) b. DC Spark-over Voltage (a-e ,b -e) 480-720V Norn. impulse discharge current (a+b-e) 20 OOOA $ c at R-1804 a. e. 5Y 1995 PLAYMASTER 30/30W STEREO AMP Exceptional performance and specifications are just a few reasons why this classic 30W(RMS) stereo amp is popular among kit builders . This superbly engineered amp is ideal for just about any music system. Al l compo nents (including heatsinks) are mounted on one PCB so it's easy to build. It comes complete as a full form kit with PCB, hardware, pre-punched rack-mounted case, pre-punched silk screened front panel and al l components. Cat K-5600 -<at>sEPT'88 SPECIFICATIONS Power Output One Channel 4 ohms 42W 8 ohms 28W Dynamic Power (IHF-A-202) 4 ohms 56W 8 ohms 38W Harmonic Distortion 8 ohms 0.025% at 25W 4 ohms 0.065% at 25W (Typically less than 0.015% at normal listening levels) Frequency Response Phono Input RIAA/IEC equalisation with in +/-0.SdB (30Hz to 20kHz) Line Inputs +0/-1d8 from 20Hz to 20kHz Hum and Noise Phone input -76d8 unweighted (ref: 1OmV / 1kHz, terminated in typical MM cartridge) Line Inpu ts -91d8 unweighted (ref: 250mV/ 1kHz) Both Channels 32W 26W 48W 38W Damping Factor Approximately 80 (8 ohms load) Channel Separation (ref:28W ouput) 100Hz -83d8 1kHz -72d8 10kHz -54d8 Input Sensitivity (ref:28W auput) Phono input 4mV (overload at 1kHz: 150mV) Line inputs 250mV CD inputs 2V (as set by optional pad resistors) Tone Controls Bass +/- 12d8 at 60Hz Treble +/- 12d8 at 16kHz Quality you con afford. Digitor multimeters ore built, to the standard demanded by professionals. They all carry on impressive range of quality features and they're built for reliability and outstanding value ... you con depend on Digitor! YOU GET MORE WITH digitor MULTI METERS • High inpoct Volox case • 'O' ring seals on every joint • Fuse and transient voltage filters • Dangerous voltage warning beeper • Complies with MIL STD 28800 Closs 111A and IEC 348 With Analogue Tone With Manual Range Override TRUE RMS DIGITAL MULTIMETER AUTO RANGING DIGITAL MULTIMETER Great value! With the advantage of analogue tone; you get a rise and/or fall in pitch with the value of the reading. One of the few meters to offer both manual and auto ranging, plus the convenience of data hold . Features: Features: 3.5 digit display True RMS Analogue tone Auto off Dangerous voltage beeper Logic, diode and continuity test Tilt stand 3.5 digit display Auto and manual ranging Data hold Auto off Dangerous voltage beeper Logic, diode and continuity test Tilt stand Ranges: DCV: ACV: AC/DC Current: Resistance: Capacitance: Cat Q-1586 Ranges: 200mV, 2, 20, 200, 1500V 200mV, 2, 20, 200, 1000V 200uA, 200mA, 20A 200ohm, 2K, 20K, 200Kohm, 2M, 20Mohm 20, 200nf, 2, 20, 200uf DCV: ACV: AC/DC Current: Resistance: 200mV, 2, 20, 200, 1500V 2, 20, 200, 1ooov 2, 20 , 200mA, 2, 20A 200ohm, 2K, 20K, 200Kohm, 2M, 20Mohm Cat Q- 1582 29 RANGE DIGIAL MULTIMETER P.. quality general purpose multimeter with standard features which you'll only find from Digitor. Features: 3.5 digit display Auto off Dangerous voltage beeper Diode and continuity test Tilt stand With Data Hold PENCIL STYLE DIGITAL MULTIMETER Reliable service in the most demanding environments. A data hold button allows it to hold a reading while you're busy. Ranges: DCV: ACV: AC/DC Current: Resistance: Capacitance: Cat Q-1584 200mV, 2V, 20, 200, 1500 200mV, 2V, 20, 200, 1000 200uA, 200mA, 20A 200ohm, 2K, 20K, 200Kohm, 2M, 20Mohm 2, 20,200nf, 2, 20, 200uf Features: 3.5 digit display Auto off Data hold and reset buttons Dangerous voltage LED and beeper Logic, diode and continuity test Ranges: DCV: ACV: Resistance: Capacitance: AC CURRENT CLAMP METER ACCESSORY 2,200, 1000V 2,200, 750V 200ohm, 2Kohm 200uf Cat Q-1580 Adding an AC current range to your Digitor Pencil style meter 0-1580 is easy 1 This device is designed to snap directly onto the end of the pencil meter, or use the lead set supplied to operate the clamp head as a split system. Range: Current: 300A (AC only) g~Ts1~g~~~~~ riBENCHMARI,~ s399s I . - - - BARGAIN PRICED COMPONENTS - - I TODAY! Simply send in this coupon and receive your monthly of Benchmark ... on us' Four pages of monthly bargains, " FAST OPTO SIGNAL ASSORTED POWER I copy unbelievable savings and handy tips. Essential read ing for the COUPLER DIODE &SCR TRANSISTORS I handyman, enthusiast and technician. Suitable for Musical Rush in and save on PACK Cat Q-1590 this 100 piece pack of assorted signal transistors. This month only! Cat Z-3000 SC)95 A great low price! Don't miss out, all this month. Cat Z-3010 Instrument Digital Interfaces (MIDI). Cat Z-4808 Unbeatable Value Top Value Save $3 s199s IV~/~ Name:. 1 Address: . I Postcode: ............... Phone: Send to: Benchmark Moiling List P.O BOX 321 NORTH RYDE NSW 2113 I .· NEW Special Introductory Price SOLDERING TOOL Super Low Price! 'POCKET' SOLDERING SYSTEM Work just about anywhere! A professional quality soldering tool designed in England. Anywhere else and you'd expect to pay around $40 for this handy butane powered iron. Yet all this month we're offering it at a special low price. It's easily refillable and has a handy liquid-gas window so you know just how much gas is left. Quality features include a temperature control of 400/ 1300C 0 , power rating of 10-60W, quality iron plated tip and an average operating time of 1 hour. Hurry in for this special low price! This butane powered soldering system is four totally portable tools in one! There's a Soldering Iron, Blow Torch, Hot Blower and Hot Knife. It has the equivalent of 10-60 watts of power and temperature adjustment up to 400°C. Ideal for the hobbyist, handyman or technician. • A Pocket sized, temperature adjustable iron • 4 tips including hot knife and blow torch • Tip cleaning sponge, plastic case & clip-on iron stand • Butane powered Average 90 minutes continuous use Cat T-1385 Normally $39.95 CatT-1374 This Month • Check out our affordable range of Nimrod quality replacement tips Only $699 ~, Exceptional Value BUTANE SOLDERING IRON A sensational saving! This totally portable, butane powered soldering iron fits easily into your shirt pocket. It's ideal for service, handymen , technicians, etc. A sensational tool with up to 60 minutes continuous use at lull power (equivalent of 60 watts) and temperature control from 10 to 60 w1;1tts. Cat T-1370 This Month Only ~ Hot Knife Cat Cat Cat Cat Cat Reduced To T-1372 T -1369 T -1371 T-1373 T-1368 s349s SCREW-IN FUSEHOLDER What a saving! You won't find a lower price anywhere. With raised screw top Now Just M-205 TYPE Only Cat T-2561 Replacement Tip 95~ ,,J $695 PCB HELPING HANDS SOLDERING AID SET It's like having another set of hands! With alligator clips, a heavy cast iron base and magnifying glass. As well, there's a soldering iron stand, flexible light and solder cleaning s onge. What a bargain! Includes a fine-point and slotted end probe, scraper end and wire brush probe, angle scriber & scraper probe, aluminiul')l heatsink and 170mm tweezers. A must for your tool box! ·-. - - ~ Cat T-5720 ' Cat P-7902 Cat P-7918 T-1375 T-1378 T-1379 T-1381 With light This Month Only 95~ · Cat Cat Cat Cat A high capacity de-soldering tool. Ideal for reworking jobs and the removal of solder from electronic circuit components. Designed for easy one-h and use, the tip and barrel are fully removable for easy cleaning. CatT-2562 BARGAIN PRICED COMPONENTS for easy fuse fitting. " 3AG TYPE Tip Tip Tip Tip DE-SOLDERING TOOL 15% off all tips! Tip Tip Tip Tip 1.0mm 2.4mm 3.2mlTI 4.8mm Cat T-1376 Cat T- 1377 Cat T-1382 Exceptional Value ; SPARE SPECIALS! 1.0mm 2.4mm 3.2mm 4.8mm 15% off all tips Hot Knife Blow Torch Hot Blow as~ Cat T-2606 s DEPENDABLE TOOLS At An Affordable Price SCOPE Save$30 20W MAINS POWERED SCOPE SOLDERING STATION An air cooled finger grip makes this iron ideal for continuous use, students, production line, professionals ... anyone. Rated at 20W, 270°C. With an earthed tip and barrel for added safety. Outstanding value! One of the most versatile, high quality soldering stations available. Technicians, service departments and hobbyists alike rely on this iron. When it comes to quality and dependability ... you can't beat Scope. • Infinitely adjustable 200-470 °C • Illuminated temperature readout • Monitors actual tip temperature • Zero Voltage protection • Burn resistant, highly fle xib le lead • Rated at 60 watts Cat T-1000 Spares: Cat T-1620 Spares: Pointed Tip Cat T-1621 4mm Flat Tip Cat T-1623 2mm Flat Tip Cat T-1625 3mm S/Driver Tip Cat T-1627 Fast Heating! 12V 30-150W IRON Ideal for outdoor service or repair work! This amazing iron heats up in just 3 seconds. What's more, there's up to 150 watts on tap and it comes with a 6 metre lead and battery clips. Current drain is 45A and operating time on a fully charged battery is approximated 1 hour (at 30W). Cat T-1635 s99s ea. 0.8mm Tip Cat T-1002 1.2mm Tip Cat T-1008 1.6mm Tip cat T-1004 3.2mm Tip Cat T-1006 s159sea. ~ k This Month Only s229 ~-.,,,,- 10-70 Watt Range! MINISCOPE Lightweight and ideal for general service work and kit building , etc. This iron has a fingertip temperature control and requires 3.3V <at> 30A so it's best used with the scope transformer (T-1692). Complete with spare tip and element. · s349s 150 Watts! 3.3V <at> 30A (lryt) SUPERSCOPE SCOPE TRA~SFORMER Select the temperature and the Superscope delivers it in just six seconds! With a huge 150 Watt capacity and stainless steel barrel for longer life. Requires 3.3V <at> 30A transformer (Cat T-1692 below). Includes spare tip and element. A high quality, low voltage transformer in a tough polypropylene case made for the Scope range of irons (T-1605 & T-1660). Saves accidental damage to sensitive components and has an electronic shield for extra protection. Complete with iron rest. Cat T-1605 CatT-1692 Spare Tip & Element Pack. Cat T-1660 Cat T-1603 Spare Tip& Element Pack. s109s Cat T-1601 s109s . ,/ / s749s FLUX CORED 60/ 40 SOLDER A general purpose electronics grade flux cored 60/40 (Tin/Lead) solder in a 200g roll. Ideal for most projects and repair work. 1.25mm (18G) Cat N-1619 25 0.71mm (22G) Cat N-1623 $7 DESOLDERING BRAID The clean efficient way to desolder. Soaks up solder just like blotting paper. Chem-Wik Life 1.9mm x 1.5m roll (green) Cat N-1680 2.5mm x 1.5m roll (blue) Cat N-1681 Ozone Safe SAFEWASH 2000 A powerful biodegradable aqueous based cleaner. It dissolves all types of organic (including flux and grease) and inorganic . residues quickly and efficiently. It's nonflammable, 100% ozone friendly and comes in a 400ml spray. Tech Wick 1.5mm x 1.5mm roll (yellow) Cat N-1683 2.5mm x 1.5mm roll (blue) Cat N-1686 ◄ , Cat N-1180 s299s NiCAD BATTERIES LEAVE THE OTHERS FOR DEAD! • In the long run NiCads are far less expensive than normal disposable batteries Outstanding Value! UNIVERSAL CHARGING CABINET $4295 - Outstanding value and perform ance. This mains powered charger allows you to charge 1, or up to 8 batteries at a time. It takes AAA, AA, C, D, and 9 volt batteries in almost any combination. What's more, it even charges three 9 volt batteries at once. With charge indicator lights, reverse polarity protection and a built-in test meter. Cat M-9505 • Up to 500 recharges per battery • Creates less waste than using normal disposable batteries For Longlife NiCads HIGH CAPACITY BATTERY CHARGER High capacity NiCad batteries last up to 3 times longer (between recharges) than standard NiCad batteries. This mains powered unit charges up to 8 high capacity NiCads at once ... in almost any combination! Charge 600mAh 'AA ', 1.BAh and 2Ah 'C', 4Ah 'D' cells and up to 4 x 9V at their correct rates. With LED indicator lights and reverse polarity protection . ~ Exceptional Value 5 HOUR FAST CHARGER This compact unit simply plugs directly into your power point. Charge 2 or 4 'AA' or 'AAA' NiCads or 1 or 2 x 9V cells. Indicator LEDs are provided for each compartment so you know your batteries are charging. $1995 Cat M-9507 GUIDE TO NiCad BATTERIES Cat M-9506 AA', 'MA' & 9V! CHARGING CABINET Here's an economical charger that's ideal for the most commonly used household batteries. Charges up to eight 'AA ' or 'AAA' NiCads or up to four of these plus two 9V cells. This mains powered charger has reverse polarity protection plus indicator LEDs for each compartment. Cat M-9508 s249s Well worth every cent! Valuable tips and advice on how to get longer life and the best performance from your NiCad batteries. Oniy 95~ Cat B-6040 -M-AJ_o_R_o-1c_K_s_M_rr•H•E-LE_C_T_Ro-N•1c•s•,.•UT-Ho•R•1s•E-D•s•To_c_K_,s_T_s_,--------. NSW: ARMIDALE: New ~land Electronics 711655 BALLINA: Ballina Electronics 867022 BATEMAN'S BAY: 7~00~~:r~1~~fo~i~e=lcmi"z..t2J8:sg::-~zi:~1u';~ITt~s4ff~f tr~~~~3kM COFFS HARBOUR: Coffs Harbour Electronics 525684 OENILIOUIN: Deni Electronics 813672 OUBBO: Chris's Hi 0 ~~ R 828711 FORSTER: Forster Village Electronics 545006 GOULBOUAN: Tunlive 221288 GRAFTON: Repairs & Spares 421911 GRIFFITH : Miatronics 624534 INVEAELL: lnverell Electronics 221821 KEMPSEY: P&L Leonard 631134 LEETON: Leeton Audiotronic 532800 LIGHTNING RIDGE: Lightning Ridge Solar Power 29 1013 LITHGOW: Oouroy Photographies 513173 LISMORE: Decro Electronic Seivices 214137 MOREE: Moree Electronics 522091 MUIJGEE: Headware 723895 MUAWILLUMBAH : Strings & Things 723684 NARAABAI: Namoi Computer Service 923274 NELSON BAY: Nelson Bay Elect & Hobbies 813685 NOWAA: Nowra Electronics 210722 PARKES: Strad Music Ctr 623366 POAT MACQUARIE: Hastings ComputerSeivice 840255 RICHMOND: Silicon Crafts 784101 TAREE: Manning Electronics 512233 ULLADULLA: Coastal Electronics 553989 WAGGA WAGGA: Phillips Electronics 216558 WALGETT: Walgett Electronic Centre 281116 WELLINGTON : Wellington Seivice 452325 WINDSOR: Hawkesbury Electronics 776722 VASS: Warmington Electrical 261116 YOONG: Keith Donges Electronics 821279 VIC: ARARAT: Jerram Electronics 522:345 BAIRNSOALE: LH & LM Crawford 525677 BENALLA: North East Electronics 622710 CASTLEMAINE: Inspect Electrics 723773 COLAC : Colac Electronics 312847 ECHUCA: Gilmour Electronics 822956 Ml LOURA: Pullman Auto Pro 232882 MORWELL: Roylaine Ply Ltd 339458 SHEPPARTON: Andrew Guyatt Electronics 219497 SWAN HILL: Nvah [);strict TV Seivice 329303 ST. ARNAUD St. Arnaud Appliances 951069 WARAAGUL: Roylaine 234255 WARRNAMBOOL: Koroit St Elec Seivices 627417 WONl'HAGGI: South Gippsland Photo Seivice 721411 OI.D: AYR: Delta Electrix 831566 BLACKWATER: Cool Tronics 825827 BOWEN: llelpro Agencies 86 34TI BUNOABERG: Bob Elkin Electronics 521785 CALOUNOAA: Electro-mart 918533 DALBY: Hobby & Electronics 625770 DYSART: Dysart Videotronixs 582107 GLADSTONE: Electronic Enterprises 726660 INGHAM: Masons Electronics 763188 INNISFAIL: lnnisfail Hi-Fi 612014 KINGAROY: MO& MMSie~e :~~W~r~r~~1\e~~t~~i~~J5i~r,~rt~~lJ~:~vci'mn~f~~~i~~~~~ 0 Electronics 411966 PIALBA: Keller Electronics 283749 STANTHORPE Granite Belt Communications 813333 TAS: BURNIE: Electronic Ci~314760 DEVONPORT: Al Electronics 248322 SA: MT GAMBIER: Hutchesson's 5l~~~~to1l~t~~: ~fW~~~tL~~fU:O E~~~~~~~i~iti~rcriir~~~:~ 2 2 ~"3~~~~:J!~~:~~~~kJ8'J%Mift~A~h 1~i~\~J:o~i~3~~ &wHes $42 95 RECHARGEABLE NiCad BATTERIES Quality Japanese made NiCad batteries in the most popular sizes. Size Desc. Cat No. Price AAA 18QmAh S-3305 95 AA 500mAh S-3300 3.50 C 1.2Ah S-3301 7. 95 7 95 D 1.2Ah S-3303 • 13. Varta TR7 /8 True 9V 100mAh Cat S-3308 $24.95 NiCad BATTERY PACKS No./Type 4xAA 2xC 2xD Desc. 500mAh 1.2Ah 1.2Ah Cat No. S-3150 S-3152 S-3154 Price 12.95 14.95 14.95 1 HIGH CAPACITY NiCads They last longer! High capacity NiCads which last up to 3 times longer between recharges than standard NiCads. Size AA C D Description 600mAh 2Ah 4Ah Cat No. S-3312 S-3311 S-3310 Price 3.95 10.95 14.95 1 OPEN YOUR EARS TO THE WORLD WITH SHORTWAVE SANGEAN SANGEAN MICRO 9 BAND RECEIVER MULTIBAND SHORTWAVE RECEIVER A pocket shortwave! The MS-101 is smaller than most AM/FM radios yet gives surprisingly good shortwave and local AM/FM reception. Highly sensitive micro-circuitry allows it to receive many international shortwave broadcasts including The Voice of America, BBC, Radio Australia and Radio Moscow. It has one-touch power, power safety lock, FM stereo & SW tuning indicator. Other features include a quality tuning mechanism, telescopic antenna and a DC jack for mains power (requires optional adaptor). Complete with earphones for FM stereo and a soft carry With this superb Sangean ATS-803A world band receiver hear the news as it happens .... from where it happens! Listen to local AM/ FM stations and , with the SSB reception facility, listen to many Military, Amateur, Marine & H.F. Aircraft communications. This quality receiver has complete coverage of the 150kHz to 30MHz range , 9 pre-set station memories and a direct frequency keypad. It has a backlit display for clear night viewing and a large 4" speaker. Separate bass & treble controls give superb sound and an adjustabl e RF gain control compensates for ~::~-2827 high power Signals. Cat 0-2831 $9995 $269 5ANC5EAN With Cassette Player! ALL-BAND WORLD RECEIVER Open your ears to the world with the stunning Sangean ATS-818CS. This fantastic receiver covers Longwave and continuous shortwave frequencies from 1.62 to 30MHz and local AM/FM stations (FM stereo with optional headphones). What's more, with an inbuilt BFO (beat frequency oscillator) it can receive many HF SSB transmissions including marine, aircraft, amateur and commercial broadcasts. An inbuilt tape deck even allows you to play your favourite tapes and pre-set it to record broadcasts. Top features include five-way tuning, 45 station memories, a full function digital display, dual time and alarm clock. A dual conversion receiver design offers switchable filters and an adjustable RF gain control to provide optimum reception . It's simply brilliant! Cat 0 -2842 $399 SHORTWAVE LISTENERS GUIDEBOOK PASSPORT TO WORLD BAND RADIO 1992 Harry Helms Essential reading! If you're thinking about getting into shortwave then this easy to follow book tells you when, where and how to hear the world talking. Topics include; choosing the right antenna, conditions affecting reception , international & domestic broadcasting and much more. Cat B-2040 A valuable guide on how to get started with your shortwave receiver. It's packed with useful information , everything from what's on to the best (& worst) SW radios. If you 've just discovered shortwave radio , are just starting out, or want to keep up with the latest world changes , this book is a definite must-have! Cat B-2050 s349s WORLD RADIO TV HANDBOOK 1992 One of the most sought after books among shortwave enthusiasts. With up to date and complete lis,tings of international radio and TV stations. Provides frequencies, addresses, call signs, ID's... you name it. n•• .... RADIO . ·-:.::;<f' \, :-,,,i,.,, ... , • ., . ~4, ·>:·.. : -~- •"~,,1, .· ...., ...., . / , ~ "'~ , . .... •; ♦ <c•»A, ..w.-~,. ,,,.,.., ,. ..,.,....,.,. ,..,., "'· Cat B-2092 s359s DS X PRESS PHONE & MAIL ORDER SERVICE HOTLINE FAX ~02) 805 1986 Outside Sydney (Free call) 008 22 6610 Sydney & Enquilies (02) 888 2105 Or write to DS XPRESS, PO BOX 321 N/RYDE 2113 STORE LOCATIONS: NSW • Albury 21 8399 • Bankstown Squ are 707 4888 • Blacktown 871 7722. • Brookvale 905 0441 • Bond i 3871 444 • Cam pbelltown 27 2199 • Chatswood Chase 411 1955 • Chu llora 842 8922 • Gore Hill 439 5311 • Gosford250235 • Hornsby 4n 8633 • Hurstville 580 8822 • Kotara 58 2092 • U verpool 600 9888 • Maitland 33 7868 • Miranda 525 2722 • Newcastle 811896 • North Ryde 878 3855 • Orange 818 400 • Parramatta 689 2188 • Penrith 32 3400 • Railway Square 211 37n • Sydney City 287 9111 • Tamworth 66 1711 • Wollongong 28 3800 ACT• Betconnen (06) 253 1785 • Fyshwick 280 4944 VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 93n • East Brighton 592 2368 • Essendon 379 7444 • Footscray 889 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 328 8088 & 246 Bourke St 639 0398 • Richmond 428181 4 • Ringwood 879 5338 • Springvale 547 0522 QLD • Booval 282 9200 • Bri sbane City 229 9377 •Bura nda 391 8233 • Cairns 311 515 • Capalaba245 2870 • Chermside 359 9255 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844• SA• Adelaide City 2321200 • Beverley 3471900 • Elizabeth 255 8099 • Enfield 280 8088 • St. Marys 277 8977 WA• Canni ngton 451 11866 • Fremantle 335 9733 • Perth City481 3281 • Midl and 2501480 • North brid ge 328 6944 TAS• Hobart 31 0800 NT• Stuart Park 811977 - SIONI Location Launceston (002) 344 555 STORES ACROSS AUSTRA LIA A ND N EW ZEA LAND A multi-sector burglar alarm Looking for an up-to-date burglar alarm system that's big on features but low in price? This unit is easy to build & features keypad entry plus microprocessor control to provide a comprehensive array of features. By MIKE ZENERE Within the last two years, there has been a sharp increase in break-ins an d burglaries. While the obvious precautions are a start, th ey really only present a small challenge to a professional thief. An effective alarm unit, however, can be a real deterrent an d will greatly increase th e security of your h ome or business premises. There is now a bewil dering array of alarm systems available to the consumer, ranging from inexpensive units to thousand dollar systems th at h ave a host of features. The un it described in this article in cludes most of the features of the expensive systems but comes at an affordable price (just $195 for th e alarm panel). Main features Because it's based on a microprocessor, this unit includes facilities that are not fo und on other alarm panels in its price range. Table 1 lists the main functions provided by the unit. They include a 4-digit programmable on/off code; three user selectable sectors (ie, each sector can be switched on or off) ; a 24-hour sector input (eg, for m onitoring a smoke detector) ; pro- Table 1 : Main Features . • Three user selectable sectors with LED status indicators. • One 24-hou r sector (for monitoring sm oke alarms, etc) • Resi stive loop sensing; can be used with both normally open (NO) and normal ly closed (NC) switches. • Inbuilt si ren driver circuit. · • Battery back-up plus automatic battery check function . • Variable entry, exit and siren duration times. • Em its warn ing beeps during entry delay pe ri od to remi nd user that the alarm is active. • Automatic loop check of siren and strobe-light lines. · • Visual and aud ible warning of any faults. 56 SI LICO N CHIP • Microprocessor controlled with automatic watchdog ci rcuit to reset unit if prog ra!TI crashes. • Programmable 4-digit on/off code. • Automatic siren lock-out if false tripping continuously occurs. • Siren , strobe light, rel ay and LEDs can be manually tested via keypad. • Optional remote keypads with LED indicators. • All variables programmable from main keypad. • Relay contacts for external circuits. • Incident report facil ity: indicates which sectors have tripped and the number of occasions. • + 12V DC 1.5A output capabi lity for siren and strobe light operation; + 15V DC 400mA rail for sensors. grammable entry, exit and siren duration times; battery back-up; automatic battery test facility; automatic testing of the siren and strobe light lines; optional remote keypads; and the ability to manually test the siren, strobe light and on-board relay. Each ofth e three programmable sectors h as a status LED on both the main box and on the remote keypads. These status LEDs indicate which sectors have been activated. Also , if a sector has been activated but not secured (eg, if a door has been left open), the corresponding sector LEDs flash on and off at th e main box and remote keypads. Note that the sectors cannot be turned on or off once the alarm has been armed . They can only be altered after the alarm has first been disarmed by entering the 4-digit on/off code. In addition to the sector LEDs, the front panel also carries two small LEDs which alternately flash when power is applied, an on/off LED (to show wh ether or n ot the unit is activated), a memory LED which lights if the alarm sounds, a keypad and a 4-character alphanumeric display which flashes the message "UNIT OK" if everything is correct. The display is also used to indicate problems and to indicate settings (eg, the on/ off code and entry and exit periods) w hen the unit is being programmed. Although its versatility might make the unit appear daunting, in practice it is very easy to set up and operate. All settings are entered via the keypad using the number keys, the (function) key and the # (enter) key. For example, to turn sector 1 on or off, you simply enter *1. Sectors 2 and 3 are turned on or off in exactly the same manner (ie, by entering *2 and *3, respectively) . Unlike the programmable sectors, the 24-hour sector cannot be turned off. Nor does it have exit or entry delay times. Instead, this sector is on permanently and is typically used to monitor fire/smoke detectors. Apart from that, each of the four sector circuits is identical and will accept both normally open (NO) and normally closed (NC) switches. Fig.1 shows how an end-of-line resistor is connected in conjunction with both types of detectors. The resistor stops a would-be thief from cutting or shorting out the input cables to the alarm. With this set up , almost any type of intrusion detector can be used. These include passive infrared (PIR) detectors, lightbeam relays, reed switches, pressure mats, window foil strips, and ultrasonic and microwave movement detectors. Because user requirements vary, the 4-digit on/off code and the entry, exit and siren duration times can be altered at any time. The latter settings range from O seconds to about 10 minutes and all settings are stored in an EEPROM. Each time variable is adjustable to the nearest second. Note that you must know the current 4-digit code in order to change any settings, for obvious security reasons. When the alarm starts counting down its entry delay period, the display panel and the remote keypads emit a beeping sound. This has two purposes. First, it reminds the user to switch off the alarm each time he enters the premises before the siren starts screaming. And second, it serves to warn off any intruder by indicating that the alarm siren is about to sound. The unit also incorporates an alarm lockout feature which monitors the number of times that the alarm sounds in one 12-hour period. This is useful if continuous false tripping occurs (eg, due to a faulty sensor) . When the alarm sounds for the first time, the microprocessor (MCU) starts an internal 12-hour timer and counts any further soundings of the alarm. If the total number of soundings in that * · · · ~TOBl Cl S£CTOR2 0 SECTOtl 3 The alarm circuitry is housed in a pre-punched steel case & all commands are entered via the keypad. A 4-character alphanumeric display is used to show the alarm status & to indicate test results & programmable settings. 12-hour period is equal to the set number, then no further alarms take place until the timer has timed out! Remote keypads Up to two remote keypads can be connected to the alarm panel and these would typically be mounted just inside a door. The remote keypads provide sector control and allow the alarm to be armed or disarmed in exactly the same manner as the keypad on the main unit. Unlike the main keypad, however, the remote keypads cannot be used to program in variables or to perform the various test functions. Seven small indicator LEDs are mounted on the remote keypads to indicate the status of the alarm - three at the top and four at the bottom. The top row carries two armed/disarmed indicator LEDs plus the memory LED, while the bottom row carries the three sector LEDs and a fault indicator LED. All keypad entries are accompanied by a beep to confirm that an entry has been made. Self-checking routines There are several se\f-testing routines and any failures are mainly indicated on the alphanumeric display. First, the battery is placed on test once a week and if it fails, the words SEPTEMBER1992 57 "CHEK" and "BATT" alternate on the display. Second, the processor constantly looks for loops in both the siren and strobe light lines and if one or both of these fail, "CHEK SIREN" or "CHEK LITE" is displayed. The remote keypads also inform the user of any faults by flashing a red LED and by making an intermittent beep, once every five seconds. As an added precaution, the board also has a "watchdog" circuit that will reboot the unit if it crashes. All variables are stored in an EEPROM, so that the unit can continue from where it left off. This ensures that the siren doesn't run continuously. Although this circuit has been added as a precaution, the chances of this happening are next to zero as all the address and data lines are internal to the MCU. Battery back-up The alarm panel is backed up by a 12V 2.6Ah battery in case of mains failure. If the mains does fail, the processor senses this and uses two methods to conserve power. First, power to the rem{lte keypads is shut off and all commands must now be entered via the main keypad. Second, approximately 15 seconds after the last keystroke, the display blanks out apart from the two flashing status LEDs. If the user subsequently hits a key after the display goes out, a further 15 seconds of viewing is available. How it works The alarm panel is made up of two PC boards: (1) a main processor board; and (2) a display board. These two boards are connected together via a 16-way data cable terminated at either end with IDC connectors. The remote keypad is built onto a separate PC board and housed in a small plastic case. In addition to the microcontroller, the processor board (see Fig.2) contains a host of smaller circuits which are vital to the running of the alarm. These include the watchdog circuit, an alarm driver, the sector inputs, line loop detectors , relay contact outputs, a battery charge and testing unit, and the transmit and receive components for the remote keypads. At the heart of the alarm panel is the 68 705P3 microcontroller. This device is a complete computer on a chip and controls the entire alarm panel. All of its 20 I/O (input/output) 58 SILICON CHIP 07 INPUT: GND ·>-------------' la) NC SWITCH INPUT u - - - - t > - - - - - - - , 10k GNDu-----t-----~ lb) ND SWITCH 10k GNDO-----t>--------' (c) NO+NC SWITCHES Fig.1: the circuit employs resistive loop sensing so that the sectors can accept both normally open (NO) & normally closed (NC) sensor switches. pins have been used and the program takes up almost all of the internal EPROM. Because the data bus is hidden from the user, port A is used to communicate with the outside world. It is used both to talk to the display board and, when programmed as an input, to receive data from the keypad and sector inputs. Timing for the system is derived from the 50Hz AC input (via bridge rectifier BR1) and this is used as an accurate interrupt for the processor every 20ms. During this time, the display board is updated, the clock is incremented and the system communicates with the remote keypads. Power·supply Power for the unit is provided by a 16VAC plugpack from which all other voltages are derived. The AC voltage is rectified by BR1 and filtered by Cl to produce about Z0VDC. The battery is a 12V 2.6Ah type and is trickle charged via R3, with ZD4 and D17 clamping the voltage to about 13.8V to prevent overcharging. Rl and RZ are used to reduce the power dissipation across REG1 , which provides a +5V rail for the ICs and their associated circuits. The Z0VDC is also fed via RB to REGZ , a 15V regulator used to run the passive infrared detectors and remote keypads. Should the mains fail, DZ and D3 conduct and feed 12V from the battery to both REG1 and the output of REGZ, thus maintaining the system. D16 protects REGZ from reverse voltage during battery operation. Fuses Fl and FZ are included in the 12V outputs to protect the system from overload, while fuse F3 limits the 15V output to approximately 400mA. This . is enough to handle two remote keypads and about seven passive infrared detectors. As mentioned previously, the MCU will shut down power to the remote keypads to conserve battery life if the mains fails. This is accomplished in the following way. When the mains fails, pin 19 (PB7) on the MCU goes low and switches off Ql 1. Ql 1 in turn switches off Q12 and this then switches off the power to the remote keypad circuit. Battery charge & test circuit During normal operation, Ql is turned on and charges the battery via R3. However, once a week the battery is placed on test for a period of one minute and, at the end of this time, its voltage is checked. Let's see how this is accomplished. First, pin 13 (PB1) of the MCU goes low, thus turning offQ3 which in turn switches off Ql. With Ql off, no charging current is applied to the battery. At the same time, Dl becomes reverse biased which means that QZ turns on and so current now flows through R4 and QZ to ground. After about one minute, the voltage across the battery is checked and read by the processor. If the voltage is slightly higher than 9V, ZD3 conducts and current now flows through RZ0 and the base-emitter junction of Q4. Q4 thus turns on and produces a logic "0" on pin 2 of IC3 (a 74HC541 octal Tri-state buffer) which tells the processor that the voltage is OK. Fig.2.(right): the processor board carries the 68705P3 microcontroller (IC1), which forms the heart of the circuit. The processor board also carries the watchdog circuit (IC2e & IC2f); the sector inputs (IC4a-lC4d); the siren driver (IC2a-IC2d & Q10); a battery charge & test circuit ( Q1-Q3); & the transmit & receive components for the remote keypads (Q7 & Q8). J1 8 r-~r-....---~-----,----....-----....---..---.-.,--------..---~ vcc ~GNO R17 68k 20 TB1 SEC 1 vcc +5V i I t----+------+---i--------------"1'1 K86 I r-------+---~--------------"OK85 ov~ j'----------+--------------'OK84 I .,. I I R48 10k I SEC PA7 11 12 IC3 PA6 74HC541 PA 13 5 PA4 14 3 2 PA3 PA2 PA1 .,. R~3 1Qk PAO PA7 PA6 PA5 ! PA4 01J PA1 15 +5V 6 +5V 17 18 C16 PA3 PA2 PAO SEC I 4 4 (24HR) PC2 PC1 OV<Y::i_ I .,. j I SEC PCO V+ R43 10k 6 J I 10 +15Vo!-+15V +12V~+12V 28 201 4.7V +12vo)2..12v 01 5 1N4004 I I +5V-'--+--~ TB2 v------oc1 ~--------------,l----4------- 8 LIGHT·U' I 5 XTAL PA7 27 ~C2 ovo½._ I .,. I I SIREN .,. I 10 18 ' - - - - - - - - - - - - - - - - - - - - - '-"! P86 R64 10k IC1 68705P1 R65 4.7k 17 P85,l-''--- - - - - ' +15V I R62 PITT~1~9-~1NO~k~--~8~ITT1 '-1=PN100 +5V R11 100k I I I I _r-1ov .,. +5V I - - - - < IX I PB3 15 PB1 PM 13 16 016 1N4004 I I I I I +5V +5V I R30 10k I I I V+ +12V 1 r-----e----1-------__:,l-----41'--.,__ __._...r,;_:F'.r>-- +12V P3 12V 2.6AH 1 111 SIDE ECB I pi ~ _...-PLASTIC VIEWED FROM BELOW T ...I... c0E ZD4~ 13V~ BURGLARALARM-PROCESSORBOARD SEPTEM8ER 1992 59 J1 vcc +5V 8 GND~ c1I 1 - C2 +5V + 1r C4 C6 01! 011 LE06 CJ 011 1 -! 9 20 PA7 g PA7 PAS B PA6 PA6 7 PA4 6 PA4 5 PA3 PA3 4 PA2 PA5 15 17 STAT CS 12 13 KB3 14 IC1 KB2 74HC574 KB1 15 LED7 PAO CS PA4 ffi CEZ WR .,. .,. +5V PC2 PC1 PCO 6 CUE GND 10 4 .,. .,. PCO KB6 KBO 11 20 2pA7 ON 3 A6 4 MEM PA5 5 PA4 6 PA3 SEC1 7 2 PA 74~i~74 B PA1 SEC2 g PAO KB4 2 KB5 KB4 CS 01-+ PC1 KB6 cTii DISP1 HPOL2416 1 .,. CUE BL PAS 17 PA4 14 PA3 13 PA2 12 PA1 .,. J PA1 2 PAO PA1 18 voo PA6 16 KBO 16 PA2 + C7 LE01 19 KB1 lB 17 KB3 0 0 80 © 0 KEYPAD1 0 0 4 0 0 ® 60 16 ~- 8EEP1 10 .,.. BURGLAR ALARM - DISPLAY BOARD Fig.3: the display board circuit includes the keypad, an HPDL-2416 4-character alphanumeric display and a 93C46 EEPROM (IC3) which stores the time variables & the current alarm status. IC1 & IC2 are 8-bit latches. IC1 provides the interface between the keyboard rows and the MCU, while IC2 drives LEDs 1-5. thus enabled again and generates another reset pulse for the MCU. Siren driver On the other hand, if the battery voltage is low, then "CHEK BATT" is displayed, while any remote keypads connected show a fault condition and beep every five seconds. The battery is then placed on charge again for one hour and at the end of this time the test is repeated . This process continues until the battery voltage reaches an acceptable level. Watchdog circuit The watchdog circuit consists of an astable oscillator made up of C9, R16 and inverter IC2e, plus an isolation circuit consisting of CB, R14, R15, D9 and IC2f. At power up, voltage divider R14 and R15 ensures that the input to IC2f is low and so its pin 12 output is high. This reverse biases D9 and allows pin 11 of IC2e to be pulled high via C9. 60 SILICON CHIP ICZe's output will thus be low and this low is used to reset the MCU. Pin 10 ofICZe remains low until the oscillator changes state some 400ms later (as set by C9 and R16). When pin 10 of ICZe goes high, the processor comes out of reset and begins normal execution. During normal operation, an interrupt occurs every Z0ms and this causes pin 9 (PC1) of the MCU to pulse high, then low. This pulse is passed through CB and causes pin 12 of ICZf to pulse low. Pin 11 of ICZe thus remains low (since C9 never has sufficient time to discharge) and so pin 10 of IC2e remains high for as long as this pulsing process continues. However, if the program crashes, the pulses from pin 9 of the MCU cease and pin 12 ofIC2fremains high. The as table oscillator based on IC2e is The siren driver consists of two oscillators, one modulating the other to obtain the desired effect. The first oscillator is based on IC2a and has tw o feedback circuits, one via R37 and the other via D13 and R38 in series. These feedback components give an output waveform with a low duty cycle and a frequency of just a few Hertz. This waveform is then fed to an RC coupling network based on R39 and C21 and the resulting sawtooth waveform then fed to oscillator stage ICZb via R40. As a result, IC2b produces an output signal that changes in frequency to give a siren effect. During normal operation, the siren will be off. That's because pin 12 (PB0) of the MCU is held low and thus pin 3 . of IC2b is also held low (via Dl0), thereby disabling the oscillator. DlO provides isolation between the two circuits, while ZD2 ensures that the voltage applied to pin 12 of the MCU cannot exceed 4. 7V. When the alarm is to be sounded, pin 12 of the MCU goes high and reverse biases D10. IC2b now oscillates and drives power transistor Q10 via parallel buffer stages IC2c and IC2d. Q10 then drives the siren. Interrupt circuit The MCU runs an interrupt routine 50 times a second to produce the necessary timing for its internal counters. This interrupt is derived from the 50Hz AC signal. The waveform is taken from one side of bridge rectifier BRl and is current limited by Rl3. Diodes D5-8 clip the peak to peak voltage to a safe level, while C6 provides DC blocking. C7 is there to filter unwanted spikes. The resultant waveform is applied to the interrupt input of the MCU (pin 2) and produces an accurate and reliable signal to keep the system in sync. Transmit/receive circuits The transmit and receive circuits are used to communicate with the remote keypads (if any are connected to the system). They use only a few parts, since most of the work is done by the software. When a logic "1" is to be sent, PB3 (pin 15) on the main MCU goes low and turns off Q7. Current now flows through R29 and along the Tx line to the remote keypads. Conversely, when a logic "0" is to be sent, PB3 goes high and turns on Q7 which pulls the Tx line low. Input stages A 12V 2.6Ah SLA battery provides back-up for the alarm in the event of a mains failure. To conserve the battery in this situation, the circuit automatically shuts offthe power to the remote keypads & turns off the alphanumeric display after a 15-second delay. The display can be re-activated at any time by pressing a key. If the input now goes open circuit, pin 8 of IC4d will rise towards Vee, while pin 9 will rise to about 2/3Vcc. This now represents a logic "1" on both inputs of the XOR gate and so its pin 10 output goes low (ie, an intrusion has been detected). On the other hand , if the input is short circuited, pin 9 will be pulled low while pin 8 will fall to 1/3Vcc. As before, this causes the pin 10 output to go low. The outputs of the four input sectors are all fed to IC3 and, at the appropriate time, latched through to the MCU. The input stages are used to link the MCU to the outside world. All four sectors are capable of connecting to both normally open and normally closed switches at the same time. This . Loop detectors The loop detectors are used to sense is made possible by the 10kQ end of line resistor associated with each sec- whether or not the fuses, siren lines and strobe light lines are all intact. tor input. Because all input stages are This feature enables the alarm to warn the same , we'll just consider input 1. the user that all is not right. Under The heart of the circuit is a 4070 normal conditions , with the unit in quad exclusive OR (XOR) gate (IC4). the standby mode , the driver transisUnder normal conditions, with the tor for the strobe light (Q9) will be off, line terminated by the 10kQ resistor, the junction ofR59 and R60 is held at thus presenting an open circuit to any 1/2Vcc. Thus, pins 8 and 9 ofIC4d are voltage that appears on its collector. If both the fuse and the line are held at 1/3Vcc and 2/3Vcc respecintact, then 12V (applied via the light tively, and so the output of the gate (pin 10) is high. C29 and C30 filter out filament) will be present at the junction ofR23 and R24 , and so Q5 will be any noise that may appear on the line. off. However, if the line or the fuse goes open circuit, then Q5 turns on and applies a logic 1 to PB6 (pin 6) of the MCU which then signals a fault. Display board The display board is used to show the status of the alarm unit at a single glance. It uses four ICs, three of which appear as latches to the MCU. Two of these (IC1 and IC2) are in fact 8-bit latches, while the third is a Hewlett Packard 4-character alphanumeric display (HPDL-2416) which is used to indicate time variables and any faults with the system. This device contains a 4-word ASCII memory, a 64-word character generator, four 17-segment drivers and the clocking circuitry. There are 10 lines of interest: PA0PA6, CS and two address lines (Al and A2) . .IC1 provides the interface between the keyboard rows and the MCU, and also selects the appropriate digit on the display using lines AO and Al. The ASCII code is presented to the data lines and then clocked in by taking CS low. The remaining chip on the display board is a 93C46 EEPROM (IC3) which holds all of the important data and is SEPTEMBER1992 61 PARTS LIST PP1 - 16VAC 1.5A plugpack W1 - red battery lead, 160mm W2 - black battery lead, 160mm L - link wire, 170mm Batt1 - 12V 2.6Ah SLA battery Screws (Type 1) - M3 x 6mm pan head Pozidriv x 3 Screws (Type 2) - M3 x 12mm countersunk Pozidriv x 4 Screws (Type 3) - M4 x 12mm pan head Pozidriv x 2 Nuts - M3 x 7 Washers - M3 shakeproof x 7 Standoffs - 4 x 6mm untapped GR1 - C.5mm rubber grommet Box1 - steel pre-punched alarm case with adhesive label RC1 - ribbon cable, 16-way x 200mm PVCD1 ,PVCD2 - 4.88mm terminal cover PROCESSOR BOARD PCB1 - BURGPROC.PCB Sckt1 - 28-pin IC socket J1 - 16-way IDC DIP FC1 ,FC2,FC3,FC4,FC5,FC6 M205 fuse clips Fuse 1,2 - M205 1.5A Fuse 3 - M205 400mA RLY1 - reed relay, PCB mount TB1 - 12-way screw terminal block TB2 - 2-way screw terminal block TB3 - 4-way screw terminal block HS1 ,HS2 - heatsink, 30 x 25 x 13mm HS3 - heatsink, 20 x 18 x 9mm P1 ,P2,P3,P4 - PC pins CR1 ,CR2 - 4.8mm female crimp receptacle Semiconductors 01 OA91 02,03,015,016,017 - 1N4004 or equiv. 04,05,D6 ,07,D8,D9,D1 0,D11, D12,D13,D14 - 1N914 or 1N4148 BR1 - WO-2 bridge rectifier ZD1 ,ZD2 - 4.7V zener diode ZD5,ZD6 - 6.8V zener diode ZD3 - 9.1 V zener diode ZD4 - 13V zener diode Xtal1 - 4MHz IC1 - 68705P3 microcontroller IC2 - 74C14 hex Schmitt trigger IC3 - 74HC541 octal tri-state buffer IC4 - 4070 quad XOR gate REG1 - 7805 voltage regulator REG2 - 7815 voltage regulator 01,05,06 - PN200 PNP transistor 62 SILICON CHIP 02 - B0139 NPN transistor 03,04,07,08,011 - PN100 NPN transistor Q.9,O10 - B0681 NPN transistor 012 - B0140 PNP transistor LED1 - 3mm red LED Capacitors C1 - 2200µF 25VW electro C2 - 10µF 10VW electro C3 - 220µF 10VW electro C4,C7,C8,C10,C11,C12,C13, C14,C15,C16,C17,C18,C19, C31,C32 - 0.1 µF monolithic C5 - 27pF ceramic C6 - 0.22µF mono C9,C20,C21,C23,C24,C25,C26, C27,C28,C29,C30 - 1µF tantalum or LL electrolytic C22 - .0015µF greencap Resistors (0.25W, 5%) R1 -33Q, 2W R2-15Q, 1W R3-270Q R4-100Q, 2W R5,R33,R34,R26,R65 - 4.7kQ R6,R7,R9,R10,R14,R17,R18, R19,R20,R21,R22,R23,R25, R27,R31,R32,R38,R63 - 68kQ R8-3.9Q R11,R16-100kQ R12-180kQ R13,R29,R30,R43,R48,R53,R58, R62,R64 -1 0kQ R15 ,R24,R28 - 47kQ R35-1kQ R36-1 .5kn R37,R40 - 470kQ R39-220kQ R41 -820kQ R42,R46,R47,R51,R52,R56,R57, R61 - 150kQ R44,R45,R49,R50,R54,R55,R59, R60- 75kQ DISPLAY BOARD PCB1 - BURGDISP.PCB Beep1 - Sonitron SMA 14 Keypad1 - 12-way keypad J1 - 16-way IDC DIP L - link wire 300mm Screws - M3 x 12mm countersunk Pozidriv x 7 Nuts- M3 x 7 Washers - M3 shakeproof x 7 Standoffs - 6mm untapped x 7 Semiconductors LED1 ,LED3,LED4,LED5 - 5mm orange LED LED2 - 5mm red LED LED6 - 3mm green LED LED? - 3mm red LED IC1 ,IC2 - 74HC574 8-bit latch IC3 - 93C46 EEPROM DISP1 - HPDL 2416 4-character alphanumeric display Capacitors C1 ,C2,C3 -1µF 10VW electrolytic C4,C5,C6,C7 - 0.1 µF monolithic Resistors (0.25W, 5%) R1 ,R2,R3,R4,R5,R6,R7 - 1kn REMOTE KEYPAD Beep1 - Sonitron SMA 14 or equivalent beeper. PCB1 - BURGKEY.PCB Keypad1 - 12-way keypad TB1 - 4-way insulated screw terminal block SCKT1 - 28-pin IC socket BOX1 - plastic case (DSE Cat. H2857) Screws - M3 x 6mm countersunk Pozidriv x 4 Screws - M3 x 6mm pan head Pozidriv x 4 Washers - M3 shakeproof washers x4 Standoffs - 12mm untapped standoffs x 4 P1 ,P2,P3,P4,P5,P6,P7 - PC pins Heatshrink tubing - 70mm, thin RC - 7-way ribbon cable x 80mm Semiconductors 01 - 1N4004 D2,03-1N914 or 1N4148 IC1 - 68705P3 microcontroller Xtal1 -4MHz 01,02 - PN100 NPN transistor LED1 - 3mm green LED LED2,LED4,LED5,LED6 - 3mm yellow LED LED3,LED7 - 3mm red LED Capacitors C 1 - 220µF 16VW electrolytic C2 - 10µF 10VW electrolytic C3,C6 - 0.1 µF monolithic C4 - 27pF ceramic C5 - 1µF tantalum Resistors (0.25W, 5%) R1,R2-10kQ R3,R6- 4.7kQ R4,R5,R7,R8,R9 - 68kQ R10,R11,R12,R13,R14,R15, R16-1kQ attached to the common data bus. The 93C46 is capable of storing 32 16-bit words , which is more than enough for the alarm. When data is to be read or written to the 93C46, the CS line is taken high and this is done by addressing IC1 on the display board. When selected, data is fed serially to the EEPROM via lines PA3, PA4 and PA5 of the processor. As well as storing the time variables, the EEPROM is used to hold the current status of the alarm unit which will enable it to continue from where it left off in the event of a reset. As an example, let's suppose you activate the unit with sectors 1 and 2 on and the alarm panel subsequently loses mains power. This will cause a reset and the processor will download from the EEPROM, thereby placing th e alarm panel in the ON mode with sectors 1 and 2 active. Five 5mm LEDS are used to indicate the status of the unit (power, memory and sectors), while two 3mm LEDs (LEDs 6 & 7) flash alternately to indicate that the system is up and running. LED 1 (orange) on the front panel (top left) is on when the unit is activated while LED 2 (red) tells the user if the siren has sounded. LEDs 3, 4 & 5 (orange) are the sector LEDs and are alight if the sector is activated. The five 5mm LEDs are driven by latch IC2 which in turn is controlled by the MCU on the processor board. The MCU presents the new data to the inputs of IC2 and then takes the PC1 (clock) line low to latch in the new LED states. The two 3mm LEDs are driven from pin 17 ofIC1. Remote keypads At the heart of each remote keypad , is another 68705P3 microcontroller see Fig.4. This uses a different program to that of the main control unit but still runs on an interrupt of 20ms. The MCU takes care of the incoming and outgoing data streams, decodes the 12-way keypad, and controls the LEDs and beeper status. The software that controls communications between the alarm panel and up to two remote keypads has been written so as to allow uninterrupted operation of the processors at both ends. In other words, the keypad will still be decoded while a transmit or receive operation is in progress. The remote keypad circuit has been designed to store up to four pushed □1 1N4004 TB1 +12V n-----+-_t--_ __....., C2 10 + CJ .,. 1ovw.:r o.1J +5V OV~ +5V 7 3 6 TIMER VCC VPP 24 PA4t-.,._'VW~i,-t--.ir+---=-H PA3 23 ON -:-PB6 4 EXTAL +5V PB5 IC1 68705P3 C4 27pf+ PB4 P83 R9 68k 20 21 22 0 0 0) 0 0 © 0 G) © 0 © © P4 PB2 PAO KEYPAD1 P6 MEMORY 17 SECTOR 2 15 SECTOR 3 14 ENTER LED7 PA2 PB1 13 BEEP1 8 PCO g PC1 PC2 PC3 10 11 01! SECTOR 1 16 PA1 PBO P5 C6 18 RES GN □ 1 2 .,. .,. 12 28 C5 + ~K 1J P7 '"~'"' ' C0E VIEWED FROM BELOW GNO BURGLAR ALARM - REMOTE KEYPAD Fig.4: the remote keypad circuit is also based on a 68705P3 microcontroller (IC1). This unit decodes the 12-way keypad & takes care of the incoming & outgoing data streams on the Tx & Rx lines. It also controls the LED indicators. keys. Thus, if the 4-digit combination is quickly keyed in, each of the keys is placed in the transmit queue and waits to be transmitted. Under normal conditions, the processor constantly scans the keyboard and tests the Rx (receive) input to see if the start bit of an incoming message has appeared. The alarm panel MCU transmits an 8-bit word every 400ms. This 8-bit word contains such things as LED status, fault conditions and the beeper on/off soft switch. To commence the transmission, a start bit (logic 0) is sent which lasts for 20ms. The remote keypad detects this on its Rx input within 100µs of the line going low. The remote keypad MCU now adjusts its own internal driven interrupt so that it is 180° out of phase with the alarm panel's interrupt. This allows it to sample the next eight bits ofincom- ing data right in the middle of each bit, thus ensuring that each word is decoded properly. As soon as the eighth bit is received by the remote keypad, the two processors reverse roles (ie, the transmitting end becomes the receiving end and vice versa). If any key has been hit in the meantime, a 4-bit data stream is now sent from the remote keypad's MCU via its Tx circuit, back to the alarm panel where the data is decoded. The Tx circuits used in these keypads are capable of transmitting data over a distance of150 metres which should suffice for most applications. That's all we have space for this month. We'll continue next month with the construction and give full details on operating the unit. Complete kits plus accessories will be available from the author. SC SEPTEMBER 1992 63 SERVICEMAN'S LOG Death rattles: a thorny problem We go south again this month, to commiserate with one J. L., who regularly livens up these notes. Maybe he lives in the Apple Isle, but everything was not apples for several weeks while he wrestled with an obscure fault in a Thorn colour set. This is a tale of woe but with a happy ending. The woe has lasted three weeks or more but ifI had known when it started what I know now, it could still have taken three weeks or more. The set was a 34cm English Thorn, model 9418, now close to 15 years old. The complaint was that it often stopped working, for no reason that the owner could discover. When it was going, it worked well and showed what he believed was an excellent picture. However, it had been getting worse and he was finally forced to have it attended to. I fired it up on the bench before he left and, according to Murphy's Law, it started and kept running. The owner said it would fail within five minutes loss Our -IS your gain - ---, ' I I II ' L ~ -· . · Fracarro's ESVU2. The really low loss VHF/ UHF mixer with areasonable price tag. Peter C. Lacey Services Pty. Ltd. P.O. Box 678 (74Fulton Ad.) Mount Eliza 3930 Tel:03 787 2077 Fax:(03) 787 3460 ACN006893438 64 SILICON CHIP but half an hour later it was still going. It did the same next morning but just before lunch it gave out a loud clattering noise and quit cold. I whipped the back off the cabinet, then switched it on again. There was another clattering protest from the chassis and nothing more. I located the 115V rail test point and hooked a meter across it. Several start-ups later I had learned nothing more than that the power supply could only deliver about 80V before it shut down. There was nothing to indicate what was causing the shutdown and finding the cause was going to give me some nasty headaches in the weeks ahead. · I had previously serviced the set some years ago for a minor problem but that didn't require a circuit diagram. This time, it was going to be different so I set about my files with a vengeance. Most of the Thorn models were actually an AWA chassis in disguise (or should that be the other way round?) but there was nothing like a 9418 among them. Neither was there anything similar among the uniquely Thorn models. Finally, in desperation, I turned to a list of AWA models that had just then arrived in the mail. The list was helpful, in an unhelpful sort of way. Instead of telling me that the 9418 used a so-and-so chassis, it said simply "Refer to Radio Rentals". Which didn't bode well for me, since the model was so old that the company was now unlikely to have any infor- mation on it in its files. Fortunately, I have a couple of mates who work for RR, so I fronted up and begged for assistance. All they could tell me was that they wished me luck with the TX9, as they called it. There hadn't been one in their workshop for many years, for which they were very thankful. They remembered the chassis as · the very devil to work on and a horrible thing to troubleshoot. In fact, this chassis is an English model and is grossly over-designed, as is their wont. It wasn't hard to see why my friends were glad that it was somebody else who had to fix the soand-so thing. On the credit side, they did have a copy of the circuit diagram somewhere and eventually turned up a much photocopied drawing, many generations from the original. But at least it could show me was how the circuit was arranged, even though many component values and part numbers were almost indecipherable. As a first approach to fault finding, I gave the board a thorough going over with a strong magnifying glass, look- ••• ,w 6:NGL\Slol T'~N-THlii::' COM'PLJ:~1N-r WA.~~ 1-r OFllis-N ~ WORKING, FoR~~0~11tS: OW~Q C.OV'-1:> l>\SCOV'~.. , likely to have a suitable replacement. At this point I put the set aside until I could contact the owner. It seemed that from this point on whatever I did was going to take some considerable tim e , whether I prov ed the transformer faulty or not. I wanted to know if he valued the set enough to pay for a long and involved repair. As it happ ened, he was away for a couple of weeks and I had time to talk to various colleagues about the baulky Thorn. My main interest was the noise it was making as it turned off. .,..,... AN'9 11-\\S O'PEiNE-D The noise could best be described as FIR.S"'r CP\N OF WORM~ "'0-\AT someone play ing 'I: s-r,;r.uc.t<: VJ rr t-\ 11-\,s the castanets . It was a loud, wooden , rating for dry joints or other physical tly sound that sometimes went on problems. This revealed nothing that and on until I switched it off to save could explain the intermittent nature my sanity. Mostly though, it just gave of the trouble. a short rattle and then quit. I had never heard anything like it A can of worms and I tried to find out from others if Next I tried monitoring the collecthey could explain it. More particutor of the line output transistor. The larly, I hoped they could suggest any shape of the pulse at this point can source other than the line output transoften indicate the type of fault that's former. eventually exposed. And this opened Nobody had any more ideas than I the first can of worms that I struck had and mostly they just shook their heads and murmured "you poor-----" with this set. Back at the bench, I needed to devise The line output collector waveform a way to check the line output transis usually a single spike of anything between 800 and 1500V, at line freformer. It was one of the very early quency. In this set the pulse was there diode-split types and I have not found but at many different amplitudes and the usual LOPT testing routines to be at many different frequencies. In fact, very helpful for checking these transI couldn't get the CRO to resolve anyformers. thing but a jumbled mess in the few It seemed as though I had two seconds before the power supply shut choices. One was to power the set down. from an external 115V source. The I didn't like the look of the way this other was to isolate the set from its job was unfolding, since the loud clatown power supply and see if the lattering noise seemed to be coming from ter would run on a dummy load. the line output transformer. If that The first idea was the easier of the proved to be faulty, the set might well two and would have be en implebe a write-off, since it was unique to mented ifmy high voltage power supRadio Rentals and nobody else was ply had not chosen to kark it. The °™~ 5~,... supply is a simp le DC source that I drive from a Variac. The output is filtered but unregulated and does a good job in cas es like this. As far as I could tell, the only trouble w as that the smoke had escaped fro m one of the diodes but I wasn't in the mood to try to replace it at that time. So that left me with option two - to get the set's own supply running. And this, at last, pointed m e in the right direction. The circuit diagram (see Fig.1) shows a link (extrem e right) th at can be used to isolate the power sup ply. This implied that the supp ly should run indep endently of the line output stage and that it was not one of those fi endish designs needing a line pulse to keep it running. But w hat kind of power supply was it? Most ofmy coll eagues referred to it a switched mo de supply but I had some doubts about this terminology; p erhaps it de pends on on e's definition of a switched mode supply. I w as more inclined to regard it as a simple transformerless arrangement w ith a switching functio n to facilitate phase controlled voltage regulation. Jose's Spanish Dancers Anyw ay, terminology aside, I fo und the link on the board and took to it w ith a pair of sidecutters. I th en wired a dummy load (a 60W light bu lb) across the supply to simu late th e absent receiver load. An d in next to no time I h ad the supp ly u p and rattling like Jose's Spanish Dancers. If anything , the n oise was now even more like the rattle of castan ets. With the line stage disconnected, it was apparent th at the rattle was coming from a large w ind ing n ear the back edge of the chassis. This turned out to be L65 (top centre), which appears to be a simple filt er choke. As m entioned earlier, this set was grossly over-designed, as is so much English equipment. The power supply alone employs three SCRs, three tran sistors, 16 diodes and innumerable res istors and capacitors . Finding out w hich of that lot was fau lty was not going to be easy. By sw itching the set on re peatedly, I learned that it h ad two m odes of failure. On e was immediate in that it started clattering straight away. The other allowed the supply to get up to sp eed but then run with the nasty rattle already described. SEPTEMBER1992 65 SERVICEMAN'S LOG - CTD By monitoring the output, I found that the first type of failure caused the supp ly to shut down as the output reached about 80V. With the other failure, it ran long enough to actually reach 115V. However, this was varying wildly, swinging some l0V either way. At other times, it would swing even higher and the supply would shut down. So that was what I was faced with and somehow I had to sort out the trouble. pacitor C147 (bottom right with C148). So this implied that all current before D82 had to be very lumpy DC. That was the start. Next, CSR2 (right of centre) was obviously wired as a crowbar protection circuit, driven either by transistor TR66 (extreme right) in the overcurrent mode or via a 130V zener D85 (below TR66) in the over-voltage mode. This circuit is designed to blow the main fuse in the event of an overload. Since this wasn't happening, I felt that I could ignore this part of the circuit, at least for the time being. CSR3 (left of centre) is another small thyristor and this triggers the gate of CSRl via transformer Tl. From here, I theorised that since the base of TR65 (centre) was linked to the slider of a trimpot marked "set 115V", this transistor had to be the error amplifier (its collector drives CSR3's gate). And because the trimpot was in a circuit across the first main filter capacitor (C147), the transistor could only be there to set a DC level on the gate of CSR3. Switching pulses for CSR3 are derived from the output of the bridge rectifier via TR62, D72 and a filter network consisting ofC138 and R168. Transistor TR62 is fed from a divider across the rectifier output and pro- How it works My first problem was to work out how the system was supposed to function. With unknown circuits like this one, I begin by redrawing the circuit diagram, omitting everything except the transistors and the main capacitors and inductors. This leaves me with the bare-bones outline of the circuit and I can imagine what needs to happen to produce the desired outcome. In this case, since there was no input filter capacitor after the bridge rectifier, we had a raw 100Hz DC supply on the anode of the main switching thyristor CSRl (top left) . The current out of CSRl passes through L65 and diode D82 (to the right of L65) before reaching filter ea- C ~ .. "',. '°" . ,.,.._. " " ' ::: ~ '., 071 u II .._ __ 11U1 111('),l(t-' \.- . ..0 ~. 0 • .0-~ ~/~\C ~~~ MJ,. 66 SILICON CHIP ~•..t\ &Clll ·~-~ :.a 0 8 UO'll't ! " . u,u DC )Of Fig.1 (below): as can be seen, the only available Thorn 9418 circuit was pretty grotty. Our draughtsman has fitted fresh labels to help identify those components mentioned in the text. Basically, the circuit uses CSRl to phase control unfiltered DC from the bridge rectifier. The output from CSRl is then filtered by L65, C147 and C148. TR65 is the error amplifier. s . ~ .. "'"°,f duces a 100Hz square wave on its collector (point 2). This is then fed via D72 to the filter network to produce a sawtooth waveform [point 3) which is in phase with the 100Hz unfiltered DC. Thus, CSR3 triggers earlier or later in the cycle, depending on the voltage on its gate. As can be seen, there are an awful lot of components additional to those mentioned and any one of them could have been causing the trouble. What I needed to do was to isolate the various parts of the circuit to see ifl could find out just where the trouble was occurring. Although the circuit diagram shows four oscillogram numbers (in circles), I didn't have copies of these. All I could do was check these waveforms and try to make sense of what I found. Numbers 1 and 2 made perfect sense. No.1 was the l00Hz ripple one would expect out of a bridge rectifier. And No. 2 was a steady square wave _ ,w:r 11.11" ec llt o· I C~I - H ~, _,. __. ~cao..... ,.,,._ --E:: ~JC\ A( .... . 111 ...&1.1 'fl{'"W{O nlOw ~~~ "lS.S IOII derived from the ripple. So far, so good. Waveform number 3 was a different story altogether. Although it still bore a similarity to the waveform at 2, it was jumping about all over the place, changing both amplitude and frequency in a completely random manner. And the waveform at 4 was following 3. My problem was to find out whether the irregularities at 3 and 4 were the cause or the effect of whatever the fault turned out to be. I began my attack by changing each of the semiconductors in turn. And while each was out of circuit, I tested the resistors around it for value. After this exercise produced nothing of any note, I started on the capacitors, removing each and testing for capacitance and leakage. Again , I drew a blank. The only thing I couldn't test was the 130V zener, D85 . But, as previously mentioned, the crowbar circuit didn't seem to be affected by the fault, so testing D85 had a very low priority. Doing it the hard way Eventually, it got to the stage where TETIA TV TIP AWA C2341 TV set Symptom: only even numbered channels can be selected from the front panel controls. There is no problem with the remote control and all channels are readily available. Cure: this was caused by a fault in the control microprocessor. The front panel selector buttons communicate with the chip on different pins to the remote control receiver, hence the faultless performance of the handpiece. TETIA TV Tip is supplied by the Tasmanian branch of the Electronic Technician's Institute ofAustralia. Contact Jim Lawler, 16 Adina St, Geilston Bay 7015. I had tested virtually everything on the board. There was absolutely nothing that showed up faulty under static tests. That meant that I had to start substituting for suspect components, AUSTRALIAN MADE TV TEST EQUIPMENT 10% discount on all test equipment. 15% discount on two or more items. SHORTED TURNS TESTER Built-in meter to check EHT transformers including split diode type , yokes and drive transformers . $78.00 + $4.00 p&p since some faults only show up under operating conditions (ie, with voltages applied). First, I replaced the three thyristors and the three transistors but this gave me no joy. Next, because there were less capacitors than diodes, I elected to replace the capacitors. And it was here that I solved the problem, although I still don't know exactly what the problem was. I began with the electrolytic capacitors: C127, C143, C144, C146, C147 and C148. The smaller of these I simply replaced but the last two were combined in one can and could only be tested for capacity and leakage at working voltage. To do this, I had to resurrect my high voltage supply but the effort was pointless. None of the electros showed the slightest sign of trouble. Next, I started on the ceramic capacitors. I ignored C136 and those around the bridge rectifier on the grounds that there was no sign of trouble on that side of CSR1/TR62. The next capacitor was the previously mentioned C138. It's a 150nF ceramic rated at 100V. I don't have ANTRIM TOROIDAL TRANSFORMERS HIGH-VOLTAGE PROBE Built-in meter reads positive or negative voltages from 0-50kV. For checking EHT and other HT voltages. $98.00 + $5.00 p&p DEGAUSSING WAND Strong magnetic field. Double insulated for your safety with momentary switch operation. 240V AC 2.2 amps. As important as a soldering iron! $75.00 + $10.00 p&p REMOTE CONTROL TESTER Designed to test infrared or ultrasonic control units. Supplied with extension infrared detector lead. Output is via a LED and piezo speaker. $84.00 + $4.00 p&p From $19 exchange plus post & pack Z'Ji I -~- T~NE~-~ Cheque, Money Order, Visa, Bankcard or Mastercard Phone (02) 77 4 1154 216 Canterbury Rd, Reve~bJ~t~;i:. 2212, Fax (02) 77 4 1154 • • • • Now made in Australia Standard range 15VA to 2kVA Large ex-stock quantities available Competitive pricing available for OE Ms & resellers • Simply the best transformers all round HARBUCH ELECTRONICS PTY LTD 90 George St, Hornsby, NSW 2077. Phone (02) 476 5854 Fax (02) 476 3231 SEPTEMBER1992 67 c.EN-rRe:) CSR~ ("R\G-H"r OF W~'S OSV\005\..V W\R&t:> AS ~ CROW6AR ?'R0"t'"e.c,...,-1ON ••• .. o any 150nF capacitors in my stock. In fact, I don't know anybody who does. But I do have a good supply of 0.15µF capacitors and I wasted no time fitting one. And that was all it took. At next switch-on, the supply came up to 115V and sat there without a flicker. At last the clattering noise that had so bedevilled the workshop had been eliminated. I reconnected the link to the line output stage and the set came good with an excellent though somewhat blue picture. A brief tweak on the screen pots soon put that right and the set is now producing a really firstclass result. Considering its age , it's quite remarkable that it works so well. Naturally, the owner was delighted . that it proved not to be the expensive transformer that I had originally suspected and was happy to pay my larger than usual bill. And I don 't know what was wrong with the capacitor. But it certainly made a mess of an otherwise nice little TV set. Thanks J. L. I sympathise concerning what must have been a really nasty 68 SILICON CHIP one. A colleague to whom I showed the circuit commented that it looked like the Thorn 8000, which was the basis for the early AWA colour sets. But he agreed that the similarity was largely superficial. The things I'm asked And from my own notes, a brief one to finish off. As I imagine most of my colleagues will testify, servicemen get asked some very funny questions at times - funny peculiar, that is. It happened to me again quite recently. I answered the phone and the caller introduced himself as a friend of one of my customers, who had assured him that I could help. And the problem? How to receive interstate country radio stations, particularly in Queensland and Victoria . And it was quickly evident that the caller hadn't a clue. He fondly believed that it was only a matter of buying a sufficiently sensitive receiver and the problem would be solved. His query set me back a bit. I suddenly realised that I had completely lost touch with such activities. It was all the rage when I was a teenager (yes, I was one once!) and advertisements for top of the line receivers always boasted that interstate reception was guaranteed. And many a tall story was told about the number of distant stations logged in one night. But all that had died out decades ago. So why the sudden interest? And what was the technical situation now? Sure, transmitter powers have increased markedly but there are also many more stations on the air, many of them sharing frequencies. I summarised the situation, as best I could, on the basis that there was little future in it. Sure, some stations might be heard at night, but not very reliably. Fading would be a problem, accompanied by distortion and adjacent channel interference. If he simply wanted to log a station, for the fun ofit, OK. But ifhe wanted to seriously follow a particular program for any length of time, well, forget it. Which prompted the logical question: why did he want to do it anyway? This caused a pause at the other end of the line . "Well, I'll tell you the truth. The TAB has been taking a lot of money from me and not giving anything back. And I've worked out a system which I reckon will beat them." (I'm afraid I laughed outright at the word "system", but he was obviously deadly serious). "The trouble is, the local radio stations are not allowed to broadcast the result of interstate races for half an hour after the · race. But if I could listen to the interstate stations I reckon my system would work". I said, "Well, I'm sorry mate but I'm afraid you're flogging a dead horse: (no pun intended). "There's just no way you can receive signals on this basis." · So he thanked me for the advice and added, "At least you've saved me spending a couple of grand for nothing". A couple of grand? Just to beat the TAB! So .what was this "system"? I'm no follower of the Sport of Kings. I recall putting a couple of bob into an office Melbourne Cup sweep many years ago but it must have been rigged because I didn't get anything back either. So I'm not competent to comment. But a couple of grand to beat the TAB? Oh well, it takes all sorts I s'pose. 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L: :., : ;:;: ; : : " ,' "H , . 1 ~~;; ":.~ ~~; \ , ,-,,,,[ , ;,,(i,HrL, ;, , , ;,H' , 1 '.:.~'.:.'. 1 '.~• •·•J..l•Hi.l . ,\ht.r r crno· er Ro· UHi~'l'\ TAN'l'ENNAS .-.,c;, ,.ri, ~;~g; STUDIO 3-SSL SPEAKER KIT SALE Cheapest in Australia? ·:· :; :'.~: '.: CTROI g~~g: 12"3wayspeakerkil crnocrno· C RO' crno· and Philips dome lweeler. Power handling 80 walls programme_ Cabinets are black and full y built. See lhe 1992 catalogue for full details_ Cal. No(s) CS-2480/2 23 Element Cal.LT-3178 43 Element cat LT-3181 91 El emen t Cal. LT-3182 gcrno ;:g:• CTRO' cmo• CTROI CTHOI CTROI CTHO' CTHOI cmo· CTRO• g~:g: CTRO' CTRCJ' CTRO' CTR()' CTRC:it CTPO' CTROI CTRO• CTROI CTRO' C TRO ' CTRO• crno• CTROI CTRO• CTRO • CTROI CTRO: crno· CTROI crnor c rnor CTRO: CTRO' CTRO' CTRO' CTRO' CTROI .::mar C RO' c m o· CTRO' CTRO '. CTROr CTROI CTROI CTROr CTRO' CTRO' CTRO' CTRO' CTRO' CTRO' CTROI .CTRO' CTRO' .CTRO' .CTROI :crno, .CTROr .CTRO• -crnor :CTROI -crno, :CTROI CS JA \n:r~~~~~;gm~d~~~;~ox -~, c ,,H r L~ $34.95 $49.50 $79 • 50 ,-. , ,ii,'.,' l,'sd ;,I'll· ·, (,;,f,f l• l· ► I ' ',f·.' ;,1 THE 12 VOLT BIBLE FOR BOATS Up until now these have been almost impossible to obtain. We have the lwo most common of the really obscure bits now available. You can buy all lhe standard obscure bits in our screwdri ver sets. TD2000 and TD2002 (see catalogue). These lwo new ones are extremely expensive because !hey are made and patented in the United States. They are Tri-wing and Tamper Resistant Torx_ These special screws are commonly used in video recorders, household appliances, power hand tools and most aircrafi including jumbos are held logelher with these. Bolh are 1/4" hex insert which fit all power drills and TAMPER RESISTANT TORX our screwdriver kits. Driver sizeT-20 ~ J a~ Size: A- _151 • J - .062" K· 0.78' Cat TD-2032 $12.95 --~ __J ,___.;__..,. --. $ 12. 95 D • L---6 }-~ By M. Brotherton This book is a nuts and bolls primer on 12 voll electrical systems for boat owners who are nol skilled eleclricians_ ll's also ideal for anybody interested in 12 volt --------- ------ power systems_ Chapters include: Basic Theory of Electri city, Eleclric Circuils, The Ballery, Wiring, Controls (switches, fuses, meters, etc) Transducers (lights, motors, pumps, fridges, consumption , etc_), MINER BROrnERTON Recharging the Battery, Troubleshooting. 174 pages, soflcover, 147 x 230mm Cat. BT-1342 II ''' ;,f• .. , ,f t,f .;, We've made a scoop purchase of Audio and Video leads. Stock up now al never to be repeated prices Cat. No. Description Length Normal Price SPECIAL PRICE Spin DIN plug to Spin DIN plug $4.95 WA-1000 1.2ml $2.95 WA-1 007 Spin DIN plug to Spin DIN plug 3ml $6_95 WA-1006 5 pin DIN plug to 4 x RCA plugs 3ml $8_95 WA-1002 5 pin DIN plug to 4x RCA plugs 1.2ml $6_95 __ . . --------1, \l\\O)l \ \ .lA~!~J~!\.. __ J I 1------ ~--II GOLD LEADS - these leads have gold plated plugs WA-1030 S pin DIN plug to Spin DIN plug - gold 1.8ml $7.50 WA-1032 S pin DIN plug to 4 x RCA plugs - gold 1.8ml $9_95 WA-1034 1 RCA plug lo 1 RCA plug - gold 1.8ml $5_95 WA-1035 2 RCA plugs to 2 RCA sockels - goid 18ml $9.95 AV-6508 BNC plug lo BNC plug - gold 1_8ml $12_50 PA-3599 RCA ski lo RCA ski adaptor Pk 2 - gold $7_95 $4.95 $6.95 $3.95 $6.95 $7.95 $4.95 I $28.95 , ,HI I: /,1\ 1 :. l .\, ,\h · L' ;,,, 1,1, •l• ( :, 1 t,, i,/ltl· :.1. ,/ .. ;,1, I :., ;,f f ',1 ·•'i•,' ,. , . L~ < :,i: L: ;,; 'L! ", C 1d• •I, "1l ,,H t l t :, ,( ,\ f.:: I! ••1l':,fit Lf ' 1 (_ ;,f 1 L! 1\ ( ;, t l ,\I· td lF ~ I f ,\I~ ; ;, ;-.: .-. . e,:,11,I, SUB C NiCad ;, , ( ,;H E LI i,1( i',H f U ,,, :,H r L! -',) .",tl • lf Sub C Ni Cads are commonly used in battery packs to power RC racing cars and cordless power lools_ Up till now, if a ballery pack failed you would need lo purchase a new pack from lhe manufacturer of the product. These battery packs are very expensive_The most common voltage used is 7_2 volts which is made up of 6 x Sub CNiCads_ So instead of being forced to pay $70 - $100 for a replaceme nt battery pack, you can now fix it yourself and save aforl une_ The Sub G's are supplied with solder labs and are rated al 1.2Ah _ L t.l., ;,fti ,I ! ;,:i, :. I ( CS JAY LAH t l t:L I tiU IIJIL,~ .;AY L, A H t:Lt:l., t riU i\ ll L :::> J • \ Yl..,1-\11c.L t:. l.,1 1' U 1'1111.., .;:, JA Y 1..,J.l.H rLc l., : HU N H,.,.~ J •• YL,.., H t ;.f, .i,r( ;,1,; ,\ l •\ : • l· $27.95 Cat. S8-2456 r .J:J)~ BOATS REF: SC JULY92. This battery discharger is specifically designed for vi deo camera or mobile telephone batteries_ II can be sel for different types of batteries from 6-12V and will saveyou money by reviving that dud ballery. This circu it is powered by the ballery under discharge and, lherefore, doesn't require a plug pack, making it completely portable _ TheJaycar kil is supplied wilh diecasl box, PCB and all specifi ed components. Cal KC-5120 $3.95 $4.95 $3.95 ••t BIBLE BU ILD THIS NiCAD BATTERY DIS-CHARGER KIT AUDIO LEAD MADNESS - INCLUDING GOLD I 1.fi r ;. .-. \Nl1,V .-, : 1 i<t OBSCURE SCREWDRIVER BITS! ATTENTION SERVICEMEN r-- f{ ~ ;,, ;,i,'I· 1,·•,l SEPTEMBER PRICE $449 SAVE $50 Recess size 3 Tension head 6-32 shear head 8-32 Overall length 25mm .', ll! [( ;, , < / Normally $499 TRI-WING !, , , : . 'I ;. ,~ ; L: tlf l•••l ~H t U 1A,C 1\H t tf I.'.. I LAH~,._! A , C:.i\H c t r ,,,i\ 'LAH i U ,\ 1 C AH f Lf l.i\1( AH LLt :, $6. 95 ea I ••r• l,\',lAH fLE 1n u,,m ... .;:, .Mf1.., Mr1 r t rl.,, • ,v1 '11 v:·, .Jh l \.,1, , 1 t t, v 1 ,,._., ~"--") ,,, 1 ,._,r-- . , • .... ,, , , ,....,, ., ...,,J 1~\'1 CAH t LE A. ) CAR l:L ~ CS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR FLFCTRONICS JAY CAH 1--LE-CTROMCS JA', CAR El F-CTRONICS JA , CAR fl fCTRONICS ,,AYCAR F-LECTRO1'ICS JAY CAil f If CS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR f Lf CTRONICS JAYCft R ELEC TROMCS JAYCAR FLf CTHO1'ICS JA , CAH elf CI HOMC', JA , CARE U CTRONICS JAY CAR f LE CrRONIC',JAYCAR EU - - LEClRONICS "AYCAR cLEC rRONIC,- JA <CAH I U ClHON ICS LECrRONICS A,CAR FLFCTRONICS JA;CAR FI FCTHOt<ICL, LcCTRON ICS "AYCAR [LFCTRON ICS JA\CAR H cCTnO'JIC>, LLCTRONIC S AYCAR EL[CT.9ON ICS· JA ,CAH t LtCTnON ICS LbClRONIC,-; 0 A , CAR ! , ! CT HO~ICS JAH.AR Fl FCTRON IC,S LtC TH ON ICS A·WAR 'Lf(;T8ONlr.S IAYCAR f-11-CTRON ICS 0 JAY CAR JAYC,\R JAYCAR .JAY CAR JAYCAR .JAY(;A R I UCTROt lLLCTJ10t ELFCTROt ELECTROt Fl FClHOt tltCTROt ,TRO' \H 1-l t HIGH QUALITY EDGE METER BARGAIN ANSWERING MACHIN /DATA CASSETTES \H ELI \H LU \H lll \H tU \H El! \H I Lf \11 tU \HI L'. \R [Li \n lU: \11 FL! \H [LI di t l f· d~ LU \H 11 t 1H 1-U 1H EU II--{ !::Lt" i.H f U d\ [ L: \JICS JAYCAR \ICS JAYCAR ~ICS JAYCAR !CS JAYCAR \JICS ,JA'-'rr,o ·w:s ,JA Cl PO ' ELECTRONICS ELECTRONICS ELECfRONIC!;; ELECTRONICS ci cr- T oA ,,. 11,""'c- · cino· ~ C.TRQr ~cmo1 I ClR•J rcrno . Cl HO ClRO CTRO ,lRO GIRO crno .Cl HO r,mo crnn cmo CTHO (.;THO (:TRO .T ITO r·n~r, crno 1 CTRO' ·cmocrno CTRO C'llO -;:110 ,rno ·cTRo CTRO CTR(, ':1RO ;mo CTRO CTRO , CTRO lRO 'RO RO C1RO 'CTRO CTRO rno -::.rno -.CTRO CTRO KA-1109 KA-111 5 KA-1116 KA-1117 KA-1119 KA-1390 KA-1550 KA-1556 KA-1574 KA-1630 KA-1660 KA-1675 KA-1682 KA-1683 KA-1690 KA-1692 KA-1693 KA-1696 KA-1699 KA-1702 KA-1706 KA-1717 KA-1718 KA-1719 KA-1720 KA-1724 KA-1725 KA-1726 KA-1728 KA-1729 KA-1730 KA-1731 KA-1732 KA-1733 KA-1734 KA-1735 KA-1736 KA-1737 KA-1738 JAYCAR JAYCAR JAYCAR JAYCAR ~U:CTRONICS ELECTRONICS FLECTRONICS !-Lf-CTRONICS 1/\vr-110 c1 ELECTRO\JICS ELECTRONICS FLECTRONICS ELE:CTRONICS c:rTPru,ur..:.. 1c.vrL1c 1--11=-rn=~n f\11rc.; 1AYr.AR ~I i=-1.TRON IC: S KITS Electric Fence 300Wamp module 300W power supply 300W speaker protector Transistor tester Freq counter 50MHz Deluxe car alarm Ultrason ic move detector 30V 1A power supply 12V lamp flasher Electric fence Screecher car alarm Dual track power supply Battery monitor DI box Voice operated relay Metronome Econ. Temp probe DMM Bench amp-signal trace 50MHz Dig Freq meter Cheap capacitance meter Subwoofer Adaptor Auto NiCad charger NiCad discharger RGB to PAL encoder Volt up 1.5V to 9V Pro series 1 power amp Pro module less mosfets VHF powermatch RF probe - suit above Pro series 2 pre-amp Transistor/Fe! tester Flexi timer CRO adaptor Quad DI box CRO Adaptor for Monitors 18V 1A Bench Supply Speech Proc lor Transceiver Karoake Box JAYCAR JAYCAR JAY CAR JAYCAR - ELECTRON ICS ELECTROMCS ELECtRONICS E:LE:CTRONICS JAYCAR JAYCAR JAYCAR JAYCAl1 JAYCAR JAYCAR JI\YCAR JAYCAR ELEC TR ONICS E:LECTRONICS ELECTRONICS ELECTRONICS ,IAYCAR !:.lfC:TRONICS JAvCAR JAYCAR JAYC AR JAYCAR JAYCAP ELECi-RONiCS E:LECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS E:LECTRONICS ELECTRONICS ELECTRONICS JAYC AR JAYCAR JAYCAR JAYCAR ELE CTRO NICS ELECTRONICS ELECTRONICS ELECTRONICS KITS AND MORE KITS $24.95 $119.95 $115.00 $23.50 $21.50 $169.50 $89.50 $34.95 $99.50 $12.95 $62.50 $37.50 $149.95 $14.95 $39.95 $24.95 $19.95 $19.95 $44.95 $79.00 $21.95 $29.95 $42.50 $27.95 $39.95 $19.95 $599.00 $47.95 $52.50 $7.50 $329.00 $32.00 $17.95 $24.95 $69.95 $159.50 $79.95 $29.95 $27.95 KA-1739 KA-1740 KA-1741 KA-1742 KA-1743 KA-1744 KC-5012 KC-5013 KC-5019 KC-5021 KC-5028 KC-5030 KC-5031 KC-5032 KC-5038 KC-5039 KC-5041 KC-5042 KC-5050 KC-5051 KC-5052 KC-5055 KC-5058 KC-5059 KC-5072 KC-5075 KC-5076 KC -5077 KC-5079 KC-5080 KC-5083 KC-5084 KC-5085 KC-5089 KC-5090 KC-5091 KC-5092 KC-5094 KC-5095 Low Voltage Cutout 240V Power Re lay Dolby Surround Sound Sine/Square Wave Generator 1MHz Pulse Generator Audio Sweeper - Low Cost Car radio power supply 16GHz Digital Freq meler 1OOW amp module Protector car alarm Train controller High Energy Ignition Optical tacho Disco Light Universal power supply Vader Voice Mini Mitter Knightrider LEDs 1/3 Graphic Equaliser CD Compressor Touch Lamp Oimmer Stereo 1/2 Octave. Eq. Multimeter Kit Radlax decoder Digital voice recorder CAP meter 1pF - 9999uF Reluctor high energy Stereo PRE AMP Sine/Square Wave Gen Horace the cricket 3 Digit counter VCR Remote control ext Discolight dimmer Two Tone Siren Sinewave Oscillator 20W Fluoro Inverter 12V Light chaser Stereo Audio Expander DTMF Decoder $22.95 $49.50 $39.95 $55.00 $89.50 $99.00 $28.95 $249.00 $42.95 $79.50 $89.00 $55.00 $49.95 $159.50 $12.95 $19.95 $34.95 $17.95 $239.00 $49.50 $34.95 $349.00 $38.95 $44.95 $99.50 $109.00 $46.95 $32.95 $149.50 $17.95 $23.95 $32.95 $39.95 $9.95 $16.95 $32.95 $21.95 $39.95 $79.95 KC-5096 KC-5097 KC-5098 KC-5099 KC-5100 KC-5101 KC-5102 KC,5103 KC-5105 KC-5106 KC-5107 KC-5108 KC-5109 KC-5110 KC-5111 KC-5114 KC-5115 KC-5116 KC-5117 KC-5118 KC-5119 KC-5120 KC-5121 KC-5122 KE-4023 KE-4029 KE-4050 KE-4052 KE-4048 KE-4698 KE-4711 KE-4724 KE-4729 KE-4730 KM-3044 KM-3050 KM-3065 KM-3068 AMAZING NEW COMPUTER BOOKS - Popular Applications Series LEARN DOS IN ADAY JAYCAR ELECTRONiCS JAYCAR ELECi-RONi CS JAYCAR E JAYCAR JAYCAR JAY CAR J,-\'r(AR LEARN WORDPERFECT IN ADAY 4 Ch Lighting Desk Masthead Amp Digital Tacho PC Voice Recorder Talking Voltmeter Steam Sound Mk2 Solar Batt Charger TV Pattern Gen Baby Monitor Light Beam Relay Guitar Mixer - 4 Channel 12-240V 40W Inverter Power Supply 0-45V BA SOW+ SOW Stereo Amp Telephone Call Timer VHF TV Transmitter Thermostatic Switch Video Switcher 12-240V 1SW Inverter Off Hook Telephone Timer 12V Gel Battery Charger NiCad Battery Discharger 240V 6/12V Gel Battery Charger 1.5V - 9V DC Converter Signal Speaker protector NiCad battery charger ETI480 SOW amp module ETl480 1OOW amp mod ETI480 power supply 4 sector house alarm Mini FM transmitter Parametric equaliser Guitar preamp Solar Generator 6000 Moslet Module Workhorse amp RS true 232 interlace FM minder bug $329.00 $49.95 $34.95 $32.95 $42.95 $19.95 $34.95 $110.00 $24.95 $32.50 $49.95 $99.00 $399.00 $299.00 $29.95 $99.50 $37.95 $129.95 $49.95 $17.95 $24.95 $27.95 $69.50 $13.95 $22.50 $14.95 $27.50 $34.50 $29.50 $32.95 $9.95 $24.95 $45.00 $13.95 $139.95 $35.00 $27.95 $11.95 All softcovers 228 x 152mm LEARN MICROSOFT WORKS IN A DAY JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E .J AYCAR E J AYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E JAYCAR E J AYCAR E ,IAYCAR E JArCARE JAYCAR E: JAYCAR E: JAYCAR E JAYCAR E JAYCAR E ,ifiYCAR F JAYCAR E JAYCAR F ,JAYCAR E JAYCAR E JAYC1\R E: JAYCAR E JAY CARE: JAYCAR E JAYCAR E JAYCAR E JAYCAH E .IAYCAR E JAYCAR F JAYCAR E JAYCAR E ,JAYCAR E ,JAYCAR f JA r CAR E JAY CAR E JAYCAR E Ji:.. i'CAR F ·JA,CARF JAYCAR l JAY CARE ,JAYCAR E J1\YCAR E JAYCAR E JA,CAR F ,JArCARF , JA',CAH f , JAYCAI, E JAYCAR f JAY CARE JAY CAR [ JA, CAR l JA ,'CAH ~ JAYCAR F JAYCAR E JA Y CA R I ,IA YCAR I JAYCAR E JAYCAR F JAYCAR E .JAYCAR f ,IA YCAR I JAYCAR E JAY CARE .JA,CAf, E ,IAYCAH I .JA1CAH f JA,CAR f .JAYCAH i ,, C AH flt CIHllN JCS \, l'AH h 1-C I HQl',J CS \, l Al< t 1 1 ( 'HllNI( ~. A"· i,h 1 1 I 1 . HUI" ('~ \, L .',R f I, r TR LlNI\.S ~, \ , l ,\f, •. i ' \ 1 l ,:.,1, ! It 1 ~ I ( .'.. H i.. - ! t \ ,l, ;, H ~ l t ( :. 1t ;,i i t l; l ~ I r .", ~ I l. f ( ,1 L,,\ f.i Il l l \ 1 AH I L'. l , , C ,\ f~ f Lf ( ~ · C :.. ~; r: Ll ( :, f , '., ( • • l ,:.p ~ L ~ ( , 1{ "', 1 I ,", f 1 ( / . H New England Electron ics Shop 17 Richardson's Arcade 067 711655 rl ~ Ballina f \ :. ;~ : , I ~ Armidale I .t ~ ~ t- ITC /, R ~' Ball ina Electronics 102A River St 066 86 7022 t Batemans Bay Gregs Record Bar Shop 2 Cilicenlre 044 72 5689 l Bathurst ~ ( 11 ( :, r'\iL : i.. , r ;, i, · ~ 1. r l, ;.; , I . ,1 f Electronic Frontiers 104 William Street 063 32 3933 :·. H . ·' l ,. ,. ,lf-, fl • ' . , , :, f, t . 1-l ~ ~ ... t:C : · ( ;,;_ ,, .',J. ' · ' LfC TR O NICS LEC TR ONICS LEC TR ONICS Ll:C l HON ICS Ll: ClRONICS J AYC AR JAYCA R JAYCAH JAY CAH J AYC AR 1:U: CTR ONICS l:Ll:ClRONJCS l: Ll:C I HO~ ICS H t- C I HO'\ JCS t I f C rHOl>. ICS J AYC AR J AY CAR J AYCAH J A , CAR .IAY CAR fLEC TR Ot\ lG, ELECTRO'\ IC~ l: Ll: C lRO '\ICS cLl: C ' HO M C~ f-1 f-CCRO NIC.S Mudgee Hervey Bay Head,,are 73 Church Street 063 72 3895 Newcastle Hervey Bay Hobbies and El ectronics Shop 9/5 Torquay Road 071 28 3722 Newcastle Fixll Shop 44 Beaumont Street Hamilton 049 61 6536 Hinchinbrook Electronics 14 Herbert Street 077 76 5022 JAYCAn JA, CAn JA • CAR J A • CAR JA •ChR Newcastle Taree Mooloolaba Manning Electronics Shop 1, 23 Pulteney Street 065 51 2233 Custom Guitarcrafl 142 Brisbane Road 074 44 8889 Pialba Coastal Electronics & Hobbytoys Shop 1/1OWason Street 044 55 3989 Stanthorpe : An [ l ; AR ; AR : AR ; AR Granite Bell Commun ications 97A Folkstone Street 076 81 3333 Newtek Electronics 102 Kembta Street 042 271620 Woy Woy Toowoomba Alphalran Electronics Shop 13 7-9 The Boulevarde 043 43 4919 Elbornes Ideal Electronics 138D South Street 076 35 8522 Keith Donges Electronics 186 Boorowa Street 063 82 1279 Cowra Electronic Sales 34 Macassar Street 063 421278 Colac Santronics Shop 15 Woolworths Complex 085 31 0445 Glen Innes Cotac Electronics 215 Murray Street 052 31 2847 Wimmera Hobby Supplier 9 Fibrebrace Street 053 82 2319 WEST AUSTRALIA Bunbury Shepparton Micro Electronics 45 Stephen street 097 21 6222 P&L Leonard P/L 36 Smith Street 065 631134 :AR ; AR ;Af1 ; AR : AJ1 RPM System Services Shop 8 Ingham Road Plaza West End 077 72 3488 Murray Bridge Elec Tee 44 Florence Street 086 32 2425 Andrew Guyatt Electronics 137 High Street 058 21 9497 Geraldton Swan Hill Direct Lighting 30 Chapman Road 099 211278 Nyah District TV Service 21 Ruthertord Street 050 32 9303 TASMANIA Burnie Wangaratta Electrodynamics 78 Murphy Street 057 21 7750 Warrnambool Electronic City Shop 17 City Square Wilson Street 004 31 9222 Opensure Electronics 51A Summerland Way 066 321772 Norfolk Electronics 134 Koroil Street 055 61 2619 Maclean QUEENSLAND Bundaberg NORTHERN TERRITORY Alice Springs Kyogle Aticetronics Shop 27 Cotes Complex 089 52 3411 Bob Elkin Electronics 65 Bourbong Street 071 521785 THE ORIGINAL WIRE WRAP TOOL- HACll AGAIN $29.95 OK BRAND WILL WRAP, UNWRAP AND STRIP Cat TH-1830 C .:.1-- ~ Lt' c :, H •. TERMINAL STRIP BARGAIN t C' •Car •.c' This is a high quality terminal strip with 20 screw down connectors. All screws have awire protector under them which holds and protects the wi re. Each of the 20 connectors has a PC pin for easy soldering to a PC board. Pin spacing is about 7.5mm. Made with ABS black plastic. Dimensions lenath 155mm width 12.5mm. Heiaht exc!udina oins 12mm. Cat HM-3204 , C .:. ;... ... ~ ~ 1 'C ;, ;, •• . E. El Ei LI El El ,A n l l ' Afl [ : SOUTH AUSTRALIA Port Pirie Horsham El L' FI : AH t l ; AR El Townsville Young Et : An I : AJ1 , , Cronau's TV 16 Torquay Road 071 281466 Wollongong l l FI LI fI : An r Ulladulla Benalla Electronics 61 Carrier Street 057 62 4488 lnverell Electronics 248 Vivian Street 067 221821 : An ; /.._H ; AR ; AH ; AR ; AR Kelter Electroni cs 218 Adelaide Street 071 21 4559 Benalla Kempsey : AR I : Ar1 I : AF, F Maryborough Hastings Computer Services 146 Gordon Street 065 84 0255 cr :,c AH f : AH I .J ,H : ::td~ E:. , An r AH F Mat's Electronics 49 Aerodrome Road 074 43 6119 Port Macquarie ; .AH f: Maroochydore Creative Lighting and Sound H Hanbury Street Mayfield 049 67 6577 Gotts Harbour Electronics 195 High Street 066 52 5684 Maclean Toy Kingdom Shop 2 The Strand Ri ver Street 066 45 3048 t [ LEC Tn C FLL CTR f =Ll: C Tf1 ( f Ll:C I H( f 11 CTRC ; AJ1 E : AH l Ingham Cowra Griffith •. :-( ., J AYC AR JAY CAR ,JAYCAR ,JA, CAil JA\ CAR LH&LM Crawford 878 Main Street 051 52 5677 lnverell :, 1 1-1 FC TR ONICS LLECl RONICS ELl Cl RO NICS l-Ll: C I HONICS 1: Ll:C I RONICS Cuffs Harbour Miatronics 170 Sanna Avenue 069 62 4534 'TC,·,; JAYCA R J AYCA H J AYCAR J AYCAH J AYCA R Hobbies and Electronics 37 Oxide Street 080 88 4098 Thom & Pollock Installations Cnr Grey & Ferguson Streets 067 321455 · l , • ELEC TR O NICS ELEClRO NICS ELEC TRO NICS t- Lf-C I RO NICS ELEC TR OM CS VICTORIA Bairnsdale Broken Hill ! t l • .J,f-i JAYCAR JA YCAR JAYCAn JAY CAR J AYCAR NEW SOUTH WALES l - I ~ l FLECTRON ICS 1-Lf- CTnONICS FI FC Tn ONICS H ! C TR U Nll,':, F,E CTRQ',IC S Jaycar El ectroni•;s is proud to announce our first list of Authorised Dealers. These dealers currently purchase goods from us on a regular basis. If they do not have the product in stock you wish to purch:ise, they will be happy to order goods in for you. Wo cannot guarantee that our resellers will have the same prices as Jaycar, as they are privately owned businesses in all parts of Australia, and are subject to extra costs including freight, etc. If you have a retail business and are interested in becoming a Jaycar Dealer contact Bruce Routley (02) 743 5222. \ · C ,\i--l 1 . f l , • l :, r, , · l :, ;.~ JAYC AR JA YCAR JA \ CAn JA, <.,A H J A , CAR JAYCAR DEALERS \, ;,H: - '. ( \,C.AH :- , i ( \ ' l ,-.,~ r- 1.LLC rRO NICc, I: LI Clf10N IC~ t LFC TnO "IJG:, f-1 t- C I HU NJC,, E-LcC IRONICS r~~~~~~~~~~~!!!!!!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-· /,H l l '. ( \ . ;,f, ~ L: \•l ·"'. f, · l: JA YCAR .J A , CAH JA , CAfl •A , L AH J A, CAR : AR E, :AR f : : AR f. : AR El :AR E• : AR F i :AR El :AR E, ;ARE, :AR El : AR El : AR El : AHL . : AR El : AR h : AR El : AR El tAR El :AR Et :AR El :AR EL tAR E. : AR E, tAR EL :AA El :AR EL :AR Et :AR EL :AR El tAR El :AR fl :AR El tAR El :AR El .AR El AR EL .AR EL AR EL AR EL AR EL AR [ l AR El AR EL ARE, AR El AR E i. f'·'I'--==~---.-,.-_-.,;,.-_-,.-.-.-.-.-.-...-.-.---..--=------------~~~~~~~~~----------------------'I ::~: [tr )iJl·,lt fgfJ1~:~:~~•~. fil:t~f "lf~ ~~tq~E1~:. ~~~ft::?!, l!! 137 • AR EL 190 Wright St (C nr. Selby St) (08) 231 7355 BANKSTOWN 363 Hume Hwy cnr Meredith St (02) 709 2822 AR EL Mon-Fri 9 · 5.30 Fri 8.30 · Sat 9 -12 Mon-Fri 9 - 5.30 Thurs 8.30pm, Sal 9 - 4 - Sun 10 - 4pm AR El ·C/1 H ,C i-.H BURANDA QLD 144 Logan Rd (07) 393 0777 GORE Hill 188 Pacifi c Hwy (Cnr. Bellevue Ave) (02) 439 4799 : : ~~ Mon-Fri 9 · 5.30 Thurs B.30 · Sal 9 · 4 Mon-Fri 9 - 5.30 Thurs 8.30 - Sat 9 · 4pm AR EL COBURG VIC 266 Sydney Rd (03) 384 1811 PAR : ~ ~~ Mon-Fri 9 . 5.30 Fri 8_30 . Sat _ RAMATTA 355 Church St (Cnr. Victcria Rd) (02) 683 3377 AR El 9 4 9 5 3 8 3 9 4 MELBOURNE CITY Shop 2, 45 A'Beckett St City (03) 663 2030 Mon-Fri · . o Thurs opm · Sat · pm AR El Mon-Fri 9 - 5.30 Fri 8.30. Sat 9. 2 Sunday 10am · 4pm :: rC l,P L.f-r" r( ;.. H L~CSPRINGVALE VIC 887-889 Springvale Rd Mutgrave (03) 5471022 PENRITH 199 High SI (047) 21 8337 AR EL rCA H LL C. . Nr Cnr. Dandenong Rd Mon-Fri 9-5.30 Fri 8.30 - Sat 9 - 2 Mon-Fri 9-5.30 Thurs 8.30 · Sat 9-4pm Su11 10-4pm :: ~ ~ , C AFI l f ( ' 1(1\H 1 ~c SYDNEY • CITY 129 York St. (02) 2671614 RHODES 6 Leeds SI (02) 743 5222 AR EL _,;;, , _ . . , ;_ _ _ _ _ _ _ _ _ _ _..,.;,;,;,;,_. . .. ; . ; _ ,_ _ _ _ _ _ _ _ _ __. :rnor r C A~ ,,c1._____..,________________,,_..,_....,..,,........,......,_, ' · r, ' Mon-Fri 8.30 · 5.30 Thurs 8.30pm - Sat 9. 4 Mon-Frig . 5.30 AR El , Cl, R , (,;..fi f( . r: ;. F, '~ r L~ r ADELAIDE SA ~i VISA 1 1111111 1C M ~ LLC l ><U Nll ,,, i CAH l l ( I Ho ,,, c(, , CAR : f C'TRO >, J(; , 1CA H cl C 'H O", JC'> JA • l AH t , f l I HU NIC J i-, cr, R C' RO NIC~ J,\, CM<I I I C l RO 'clC c. IA, C Afl EU C TR O ~I CS ,u JA , C AH' I ! C fR O ",I C!, A · C AR ., A' U ,H cl EC TR ONICS J A' CAR J A, CAf1 f LEC Tl10 NICS JA , C AR . l ~ Al l flrC TRO N:C~ JA, C AR cLE Cl RONIC S EL:.CTRO NIC S f LECTROMC S ELECTRONICS 1111111 .JA YC AR JAYCAR JA YCAR J AYCAR ELECTRONI CS ELF CT RO M CS ELECTRO'JI CS l Ll ClHONICS JA YCAR JAYCA R J AYC AR J AYCAR ELEC TR OI\I CS ELEC TRONICS ELECTRONICS ELEC TRO NICS JAYC AR JAYCAR JAYC AR JAYCA R ELECTROM CS J AYCAR ELFCTR ONI CS ,J AYCAR ELEC TRO NICS .I AYCAR 1:Ll:ClRO NICSIJ AYC AR ELEClRONICS ELE CTRONICS ELECTRONICS c LE CTRONICS JAYC AR JAY C AR JAY CAR JAYCAR 1:LEC TROI ELECTROI ELECTRO! ELE ~ I PRODUCT SHOWCASE I Just perfect for the home office or small business." Hatadi can be contacted on (02) 997 7077. Heavy duty lead bender Hatadi introduces CAS fax/scanner Hatadi Electronics Corporation Australia Pty Ltd has introduced the GUIS Fax/Scanner/Copier/Printer to the Australian market. The ETFax-7 is a stand-alone fax machine with a fully CAS compliant RS232 port. "Now you can use your computer as a fax machine and have the benefit of a full page scanner all in the one product" said John Bishop, Managing Director. "The Full Link software bundled with the product gives the user a Windows interface packed with features. "The main challenge with fax cards is that it is difficult to send a piece of paper by fax. The ETFax solves this problem easily and simply. Just press the send button to scan up to 5 pages and send the fax - you can even add other files, scan more pages and then personally address each fax if you are sending them to a group of people! TV signal meter has liquid crystal display The Model 951 TV Signal Level Meter from Leader is claimed to be the world's first capable of displaying eight channels simultaneously. It can be used for all Australian UHF and VHF channels as well as FM and CATV, and measurement is made with just a touch of a button. Signal levels in the range 46MHz to 8 70MHz are displayed on a large, easy-to-read backlit liquid crystal display, all autoscaled and with audio and video carrier levels shown in both bargraph and digital form. Four groups of eight channels can be preset and the data from the groups saved in memory. Automatic compensation is carried out for variations in signal level that are related to frequency and temperature, so that high measure- Three models of the Scope SLB400 bender are available for processing axial components with copper or steel leads. The new model SLB400T deals with component leads up to 1.2mm in diameter. The base model SLB400 deals with leads up to 0.8mm diameter and bends with 6.0mm minimum hole centres. The model SLB400S is for hole centres down to 5mm and leads not exceeding 0.5mm in diameter. For further information, contact Barry Maclntosh, PO Box 63, Niddrie, Vic 3042. Phone (03) 338 1566. ment accuracy is ensured. A peak detector circuit allows the unit to display the peak signal level. Housed in a case measuring 213 x 120 x 200mm, the Leader 951 is powered by 8 D-size cells, with an Auto power-off facility operating about five minutes after the last key activation. Portability and ease of use make the Leader Model 951 an ideal choice for a wide range of installation and on-site maintenance applications. For further information, contact AWA Distribution, 112-118 Talav13ra Rd, North Ryde , NSW 2113. Phone (02) 888 9000. SEPTEMBER 1992 73 Deluxe car alarm with central door locking One of the most enviable features of new cars and the latest deluxe car burglar alarms is central door locking. There is no need to fiddle about with door release levers to gain access to the rear seats so passengers can get in or to remove parcels - just press the transmitter button once to disable the alarm and all the doors are unlocked too. Nor do you have to bother to check that all doors are locked when you leave your car just press the transmitter button once to enable the alarm and all the doors are locked automatically- it really is a very worthwhile feature. Of course, you don't have to engage the alarm every time you enter or leave the car. Merely using the driver's door key will unlock or lock all the doors. The good news is that you don't have to buy a new car or go to the trouble of having an expensive alarm fitted to get these advantages; just buy this deluxe alarm from Jaycar, fit it yourself and save a bundle. Hard disc drives from Rod Irving Electronics Is your hard disc drive getting crowded with all that software you keep loading on it? Maybe it's getting a bit long in the tooth anyway and the day when it finally crashes is getting closer all the time. Instead of waiting for the fateful day, you could take the plunge now and upgrade to a much larger hard drive. This 85 megabyte drive made by Western Digital took our fancy. It has a 17ms access time, with 980 cylinders and 10 heads. It's housing is tiny, 74 SILICON CHIP The alarm comes with everything you need: two transmitter key fobs (handy for when two people drive the car); one ignition cutout relay; four motorised door locking actuators (one master and three slave); the electronic control module; and a relay which does the switching of the door actuators. Also supplied is a complete wiring harness with all leads fitted with bullet connectors. Installation instructions and a at 146 x 100 x 25mm, about the same dimensions as a standard 3.5-inch floppy disc drive. At just $475 from Rod Irving Electronics, it is an absolute bargain, especially when you consider hard drive prices of just a few years ago. If you are updating an older machine, you will probably need an IDE hard disc drive controller and these are also available at very reasonable prices from Rod Irving Electronics. Or maybe you'd like to go for an even bigger hard drive - see your Rod Irving Electronics stores in Sydney (74 Parramatta Rd, Stanmore) or in Melbourne. High temperature humidity transmitter Novatech Controls has developed a high temperature humidity transmitter. It uses a zirconia sensor which is capable of measuring humidity and percent water vapour at temperatures from ambient up to 600°c. wiring diagram are supplied and connections are required to door, bonnet and boot switches as well as the ignition key switch. The complete kit is available for $269 while the siren horn is an option at $19. 95. Also available is a backup battery siren (with a backup battery built into the siren housing) at $49. 95. See the whole range of car burglar alarms and accessories at any Jaycar Electronics store. l!l,0-"ti! " ©O t:~,!Ul A(,Jlm The transmitter measures the amoU:nt of water vapour in a dryer or flue gas atmosphere. It allows regulation of the dryer atmosphere to a constant water vapour content, thus saving energy and allowing more consistent product quality. For further details, contact Novatech Controls in Melbourne on (03) 645 2377. Compact speakers for music or public address systems These compact loudspeakers from Arista, model SP352LT, can be used in a wide range of situations at home, in a car or recreation vehicle, in a boat or in commercial public address applications . For PA work, the speakers are fitted with an internal 70V/ 100V line transformer and a rear-mounted switch allows the power level to be switched to 1W, 2W, 4W, 7.5W or ITEM 15W. Used as conventional extension speakers, the units have a nominal impedance of 8 ohms and are rated to handle up to 35 watts (presumably on music program). As can be seen from the photo, they employ a 15mm dome tweeter and a 75mm woofer. Frequency response is rated at 90Hz to 18kHz and their overall dimensions are 190 x 125 x 125mm. Their weight is 1.5kg each. Mounting brackets are provided and allow the units to be attached to a wall and angled for best effect. Recommended retail price for the SP352LT loudspeakers is $159.95 a pair. They are available from any Arista stockist. A simple, intuitive and very powerful teaching tool, Electronics Workbench lets students and hobbyists design and test both analog and digital electronic circuits, without the delays and expense of a laboratory . FEATURES • Quick and simple circuit entry • Digital and Analog Modules included, complete with all components • Simulated instruments: dual trace scope, spectrum analyser, function generator, multimeter, digital word generator and logic analyser • Complete control over all component values and parameters • Print: circuit schematics, parts list, instrument readings, macros • Logic conversion - truth table to Boolean formula to logic gates • Custom• isable hypertext help system THREE VERSIONS • Professional Version: EGA/VGA colour display ; unlimited components • Personal Plus Version: Monochrome display; unlimited components • Personal Version: Monochrome display; limited to 20 components per ... EMONA INSTRUMENTS NSW ......................... (02) 519 3933 VIC ............................ (03) 889 0427 OLD .......................... (07) 397 7427 DISTRIBUTORS Perth ............. .... ... .......... (09) 244 2777 Adelaide .. ....... (08) 362 7548 Hobart .......... .. .... ..... ..... . (002) 34 2233 UNIT PRICE 500 · · · · · · · · · · $0.01 20· · · · · · · · · · · , $0.25 20· · · · · · · · · · · · $0.25 50· · , · · · · , · · · , $0.10 25 · · · · · · · · · · · · $0.15 25- · · · · · , · , , , , $0.15 50· · · · · · · · · · · · $0.15 28· · · · · · · • · · · · $0.50 50· · · · · · · · · · · · $0.15 1 · · · · · , · · · · · · . $2.00 25 · · · · · · · · • · · · $0.15 25 · · · · · • · · • · · · $0.15 25· · · · · • · · • · · • $0 .15 25· · · · · · · · • · · · $0.15 25· · · · · · · · • · · · $0.15 25· · · · · · · · • · · · $0.15 25· • · · · • • • • • · , $0.15 25· · · · · · · · · · · · $0.15 20· · · · · · · · · · · · $3.00 9 · · · · · · · · · · · · $1.00 9 · · · · · · · , · , , . . $1 .00 13· · · · · · · · · · · · $1.00 ALL STOCK NEW & IN ORIGINAL PACKAGING ORDERS ACCEPTED IN PACK MULTIPLES ONLY OFFERED UNTIL STOCK ALL SOLD CASH, CHEQUE OR BANK CARD, ADD 20% SALES TAX, PRICES FOB ARTARMON, P&P $6.50 AUSTRALIAN TEST ~ AND MEASUREMENT~ 1 P .hLtsoAxCN732 im-ARMON ~ 02•9062333 NSW 2064 LID-_ 02-4384219 Electronics Workbench® The electronics lab in a computer! PACK MULTIPLE 1N4148 · · · · · · · · · TIP142 (TOP3· · · · · · · · · TIP2955 (TOP3)· · · · · · · · LM358· · · · · · · · · · · · · · LM324· · · · · · · · · · · • · · LM339· · · · · · · · · · · · · · uA776 · · · · · · · · · · · · · · NE565 · · · · · · · · · · · · · uA7905 · · · · · · · · · · · · · LM323K (T03) · · · · · · · · CD4053,. • · · · · · • • , · · · 74HC10- • • · · · · • • , · · · 74AC14, , , · · · , , · , , , · 74LS47· · · · · · · · · • · · · 74LS10· · · · · · · · · · · · · 74LS37• · · • · · · · · · · · · 74LS02· · · · · · · · · · · · · 74LS90 · · · · · · · · · · • · · MM74C926· · · · · · · · · · · MC6803 · · · · · · · · · · · · MC68HC05P2· · · · · · · · · MC6854 · · · · · · · · · · · · EmonaLAB4 Four instruments in one package! The LAB4 has four full function test instruments : ■ DC POWER SUPPLY Triple output ; 5V, 15V, 0-50V ■ with neatly laid out and labelled front panel controls. Also, the LAB4 is compact and only takes up a small space, compared to four bench-top instruments. DIGITAL MULTIMETER Full function, auto-ranging ■ FUNCTION GENERATOR 0.02Hz-2MHz, with SWEEP ■ FREQUENCY COUNTER 1Hz-100MHz input range INDEPENDENT INSTRUMENTS Each instrument in the LAB4 is completely independent and can be switched ON or OFF as required. The LAB4 has only one 240V mains input, saving on multiple power points. Each instrument is clearly defined EMONA INSTRUMENTS NSW ....................... .. (02) 519 3933 VIC ....................... ~ ... (03) 889 0427 OLD .......................... (07) 397 7427 DISTRIBUTORS Perth .... .................. ...... .. (09) 244 2777 Adelaide ... ...... ... ...... ...... (08) 362 7548 Hobart ........................... (002) 34 2233 SEPTEMBER1992 75 Hand held electrostatic fieldmeter The Trek Model 512 is ideal for monitoring the effectiveness of antistatic devices, materials and processes used to control static charges. It uses a chopper driven design instead of capacitive coupling to eliminate cumulative drift during use. This also allows accurate measurements in charge controlled environments using ion generating systems. For further information, contact Elmeasco Instruments Pty Ltd, 18 Hilly St, Mortlake, NSW 2137. Phone (02) 736 2888 . COMPONENTS - ' Are you sick of being told that the components you are always looking for are either not available or discontinued??? ~ ~ ~ Call us now. We specialise in discontinued electronic components (03) 742 7330 Catalogue available upon request and trade enquiries are most welcome. -~ /> '-J0"18'1T CO"t"'IUN,04TIONS SUPPLIERS & IMPORTERS OF ELECTRONIC COMPONENTS 131 GREAVES ST. NTH WERRIBEE, VIC 3030 76 SILICON CHIP PHONE: (03) 742 7330 FAX: (03) 741 6834 Handheld real-time frequency analyser Hewlett-Packard has introduced the handheld HP 3569A real-time frequency analyser which meets IEC and ANSI acoustic-measurement standards. Priced at $20,500, the HP 3569A is claimed to provide a performance equal to the most popular real-time frequency analyser at half the price. The HP3569A has the following capabilities: (1) realtime octave - 22.4kHz single-channel and 10kHz twochannel measurements with octave and one-third octave resolution, which meet IEC 225-1992 Class 1 and ANSI Sl.111986 Order 3 Type 1-D specifications; (2) sound-level meter - single-channel broadband measurements with A, C, linear and flat weighting, plus SPL, Leq and Ln computations which meet IEC 651 and IEC 804 specifications with Type 1 impulse (I) performance; and (3) real-time sound intensity real-time octave or one-third octave intensity measurements to 10kHz which comply with IEC 1043-199X with Class 1 performance. In addition, there are two measurement options: narrowband fast Fourier transform (FFT) (Option 1rmfli'illl tJ tJ t.J O f;J lJ tJ l!JOtJ a L fiH.B t;J O El AY2) giving two-channel measurements with DC to 20kHz frequency spans and real-time digital zoom; and reverberation time (Option AY3) giving single-channel, reverberation-time computations in octave band or one-third octave bands. List prices are as follows: HP3569A real-time frequency analyser $20,500; Option AY2 narrowband FFT $3,200; Option AY3 reverberation-time measurement $3,200; Option 550 data transfer utilities for the HP 95LX Palmtop PC $400. For further information, phone Hewlett-Packard's Customer Infor- . mation Centre on 008 03 3821. Neat speaker bracket from Altronics While there are a number of speaker mounting brackets on the market, this new model from Altronics must take the prize for compact and ingenious design. Whimsically named the "Wacki Bracket", it is made in two parts. The flat steel section, finished in powder coated enamel, is screwed to a wall or ceiling while the mating plastic section is screwed to the back of the loudspeaker. The two halves are then screwed together with a large hand nut. The hand nut tightens a ball joint which enables the speaker to be held at any desired angle. The Wacki Bracket is suitable for speakers weighing up to 5kg and is available in a black or white finish. They retail for $39.95 a pair and available from Altronics in Perth or their resellers. SC FOR CHIPS .. WOOD FOR CHIPS...WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... New Lab 4Everything you need in a single instrument! Ideal for the professional and keen hobbyist. Saves bench space. High accuracy yet low cost. Just check the features - Function Generator • Sine, square, triangle , skewed sine, pulse, TTL level square • Covers O.OzHz to 2MHz • Output from 0.1 Vpp to 20Vpp • Linear and Log sweep - 20ms to 2s (int) or 100:1 VCF (ext) • 50Q/600Q output Frequency Counter Analog Module includes • Comprehensive parts bin includes op-amps, zeners , transistors etc • Function Generator with sine, square, triangle etc • Oscilloscope with dual trace, inVext trigger, nanosecond timebase upto 999MHz • Bode Plotter for frequencY. responses and phase shift (-200 to +200dB) • SPICE Simu lation plus transient and steady-state simulation e Digital Multimeter e 3 1/2 digit LCD • Auto/Manual ranging • Vdc, Vac,Q, Ade, Aac functions • 0.5% basic accuracy e Data Hold • Memory mode for relatiuve measurements and zeroing Q's Power Supply • 3 1/2 digit voltage display • Triple output e Oto 50V, 0.5A e 15V 1A and 5V 2A fixed • 1mV ripp le • Full overload protection Incredible value - $837 .00 inc tax $722.00 ex tax The Best Yet! ~ 5: (.) ex: DIC o..-:. t2 SC-7000 ~ Cl DeSoldering § Tool - ESD* ~ Protected ~ ex: t2 Cl § ~ ~ ex: t2 YES you can now build; simulate and test Analog and Digital Circu its without raying vour hands on a single componentf It's so easy with Electronics Workbench®. Do it all with the mouse - drag new parts from the parts bin, drop them onto the breadboard and click to run wires. Editing circuits is easy as wires are re-routed automatically. It's much faster than buildin~ real circuits . No faulty parts I Its the result of 1Oyears innovation and thousands of students, hobbyists and engineers have been using the Workbench since its introduction in 1988. • • • • • 1Hz to 100MHz 15mV sensitivity to 60MHz 0.1 to 1OOHz resolution 10ms to 10s gate 10MHz reference , with Sppm stability 8 digit display with annunciators • Now with 100W ceramic heater • Sensor feedback digital temperature control • Work on up to 12 layer boards • • Special antistatic housing and zero crossover switching to protect sensitive components • Suction/Hot air blow switch suck for desoldering, blow for SMD removal • Optional surface mount kit $482. 50 ex tax $579 inc tax PC-based Protocol Analyser & Data Line Monitor Electronic Workbench The Electronics lab you keep in your PC! Digital Module includes • Comprehensive parts bin with gates, flip-flops, half adders, displays etc • Word Generator up to 16x8-bits • Logic Analyser with 8 channels, inVext trigger • Logic Converter converts between gate, truth tab le and boolean Professional version has inhanced colour interface, supports maths coprocessor. Requires IBM AT or PS/2 with 286 or greater, hard disk, 640kB RAM , Microsoft mouse, EGANGA and DOS 3.0. $429.00 Personal Plus Version is monochrome. Requires PC/XT/ AT or PS/2 , 2 floppies or hard disk, 512kB RAM , Microsoft mouse. CGA/EGANGA/ Hercules graphis adaptor and DOS 3.0 or greater. $299.20 Run Your TV from a Car Battery with My-Power 200 Yes this hand-sized inverter will run a 33cm TV for up to 6hours from a 12V car battery. • Gives 240V, 50Hz from 12Vdc • Rated to 400W surge (200W peak and 140W cont). • Has overload and undervoltage protection. • Full 12 month warranty. • Measures only 50x135x74mm and is great value at $180.00 Looking for Value in Multimeters? SerialTest See the review in Electronics Australia March 92"Electronics Workbench is certainly the easiest simulator I've ever used" Peter Philips The new version of Serialtest turns ANY PC into a full-featured serial data protocol analyzer even laptop and notebook computers - for both synchronous and async data. Serialtest unleashes the power of your PC for data communications testing with a simple, userfriendly interface and either! The new Com Probe plugs in to your printer port. With Serial/est and your PC, there is no longer any need to buy or rent expensive, dedicated protocol analyzers. Look at ALL these features Protocols: Async, SDLC, Sync, X.25, HDLC, SNA Data Capture: data bytes, control signals, and error conditions. Capture data to RAM and directly to disk with no file size limit. Data Display: The Serialtest package includes Serialtest software and Frontline's Frame/Packet level: one decoded frame/packet per line. RS-232 Com Probe"' adapter. The ComProbe connects to your Byte level: split-line DTE over computer via the parallel printer DCE or mixed using reverse port (no need for plug-in cards) video for DCE. and allows Serialtest to work with Characters displayed in hex, both synchronous and asynchronous devices. ASCII, EBCDIC, or Baudot. Nonprintable characters Serialtest's monitor mode shows displayed using hex, you exactly what information is flowing between any two serial mnemonics, graphics.dots. devices - both data bytes and Captured data can be searched; control signals. Source mode search patterns can include allows you to interactive!y simulate either the DTE side or wildcard characters. OGE side of the communications Control Signal Display: link. Live breakout box mc1u11es Serialtest Async is similar to timing diagrams and Serialtest, but is limited to asynccounters. only testing. The package includes Captured control signal Serialtest Async software and transitions can be viewed in custom cabling which works in conjunction with the serial ports relation to captured data on your PC. bytes using timing diagrams. Timestamping: Absolute or Anyone who works with serial data communication needs relative display of event time. Serialtest. Fie ld service eng ineers Delta time and effective data and system integrators will rate calculations. appreciate the portability and ease-of-use. Communication Triggers: Character strings, specialists and network control signals, and error supervisors will enjoy the power conditions can be used to and flexibility. No matter what the industry, Serialtest will prove to activate and deactivate data be an indispensable tool. capture. String triggers can include wildcard characters. ---------Device Emulation: Transmit data entered from the Then we have blue LEDs to suit in keyboard, Serialtest capture 3 and 5mm with a water clear case. 14mcd (typ) brightness at files, or any DOS file. Modify 20mA and 3.0V (typ). 5V reve rse. control signals. Use hardware 470nm wavelemgth and 30° and software flow control viewing angle. Both sizes $3.95ea, $3.55 (10+), including user-defined XON/ $3 .20 (50+), $3.00 (100+) XOFF characters. Configuration Management: Name and save an unlimited number of configurations. User Interfaces: Pop-up menus and context-sensitive help allow new users to be up and running quickly. Command Its easy to link telephone line options can be used to equipment fitted with American 6 slot 6 pin plugs in to an Australian further simplify operation FEELING BLUE? NEW Telephone Plug & Socket Adaptors system with our adaptors. Four pins are wired. Adaptors are · a bit thicker than standard Aussie parts. American socket to Au stralian socket 610M $5.95 American socket to Australian plug 605M $5.95 SerialTest Sync/Async with Comprobe $2480.00 (ex ta>t) $2536 .00 (inc tax).Plug Pack $24 .95. Allow $15 P&P SerialTest Async is sti ll $480.00. Demo disk $10.00 refundable on purchase Then take a close look at these APPA multimeters. Look familiar? That's because they're sold und er different brand names. It's called 'Badge Engineering ' A~pa makes the multimeter, but it s sold with someone else 's name on it. And that means you could pay a lot more than you need to. We've seen the top of the line model selling at around $150 more than our price So you 're paying that much extra just for the brand label! It's also an indication of how good Appa meters are that other people want to put their names on them I Mail Orders add $5.00 min to cover postal charges. Next day delivery in Sydney add $8.00. - All prices include Sales tax unless stated otherwise. G Tax exemption certificates accepted if the line value ~ exceeds $10.00. u:. BANKCARD, MASTERCARD, VISA, CHEQUES or CASH cheerfully accepted. ::s.. ~ § $ ~ :0 2 9l ~ CJ ~ :0 2 9l • Extra tough for industrial users • High energy fuse and PTC protection against overloading · • 0-rinp sealed case, switch and Jacks against dirt and moisture • Protective holster and lilt stand with lead storage • Test probes have finger shields and sleeved plugs • Thick walled ABS case and shock mounted LCO withstands Zm drop on to concrete floor • Unique rotary switch with berrylium copper contacts and gold plated pcb Model 103 & 105 • 4000 count • Digital update twice/seco nd, analog 20 times/sec • 8 Functions - Vdc, Vac, Ade, Aac, Ohms, Diode, Continuity, Frequency, Capacitance • Data hold & Relative functions • 0.5% de accuracy $298 .80 $249.00 ex tax Ranges Vdc 400mV, 4V, 40V, 400V, 1000V Vac 4V, 40V, 400V, 750V Ade 4-400mA, 1OA Aac 4-400mA, 1OA Ohm s 4000, 4kQ, 40kQ, 400kQ, 4Mn, 40MQ Frequency 1OOHz, 1kHz, 1Ok Hz, 1OOkHz, 1MHz Capacitance 4nF, 40 nF, 400nF, 4µF. 40µF Model 105 has similar specs but with improved accuracy of 0.1 % typ on Vdc and 0.5% at 50Hz $358.80 $299.00 ex tax Cl ~ 8.30am to 5.00pm Mon to Fri. 8.00am to 12 noon Saturday. ~CJ Geoff Wood Electronics Pty Ltd (inc in N S W) § CJ ~ 229 Bums Bay Road,, Lane Cove West N S W 2 (Corner Beatrice Street) ~ Mail Orders to - P O Box 671, Lane Cove N S W 2066 ~ Telephone : (02) 428 4111 Fax : (02) 428 5198 8 CJ Build this unit into your next power supply project A general-purpose 31/2-digit panel meter Looking for a general-purpose 3½-digit panel meter that doesn't cost the earth? This unit has switchable decimal points and can be built to read either current or voltage. By DARREN YATES There are many situations where a moving coil meter just isn't accurate enough. For example, have you ever tried to set a power supply accurately when using a moving coil meter? You've probably found that you were about half a volt out if you bothered to check it later with an accurate digital voltmeter. And when you're working with TTL circuitry, any inac- curacies can spell the end of an IC or two. Of course, there are still places where moving coil meters are useful, particularly when you wish to see the rate of change in a voltage or current. But for accuracy and precision, a digital panel meter module is definitely the way to go. Building this panel meter is straight- Power for the 3½-digit Panel Meter can be derived from a 9V battery or from any convenient 9V rail. By changing a few onboard components, the unit can be configured to read voltages up to 200V or currents up to 2A. forward thanks to the use of an Intersil ICL7106 3½-digit A/D converter IC. In fact, many digital multimeters are built around this very IC. The manufacturer takes the basic chip and adds extra circuitry and switching so that the multimeter can read resistance, voltage, current and capacitance over several ranges. This project is essentially a stripped down multimeter that can be customised as a panel meter to read voltage or current. By simply selecting a few resistor values , the unit can be configured to read any voltage up to ±200V DC and currents up to 2A (actually 1.999A). There are many potential applications for the unit. For example, it could be built into a variable power supply for monitoring voltage or current (or both with suitable switching). It could also be used to display the output from a transducer in an industrial application (eg, temperature measurement). You could even use it to monitor the track voltage of a model railroad layout or as a car voltmeter to monitor the charge on the battery. Inside the 7106 Let's take a closer look at the internals of the 7106 3½-digit A/D converter. Essentially, the IC has everything necessary to make a simple 3½digit LCD meter. It has 7-segment decoders and drivers a 4-digit counter, a voltage reference, a clock circuit and an AID converter all built into the device. The AID converter is based on the dual-slope conversion technique. This technique relies on charging and discharging an integrating capacitor, and allowing a counter to count up during the time that the capacitor voltage is 78 SILICON CHIP ,l; tl. 'I" 10 + 9V : 16VWI _,_ + IN !'._UT ·1 - Rx1 35 32 1M Ry2 15 A1 e114 3 C1 01 2 36 REF HI VR1 10k Rx2 o-Ry1 1 15k .,. RA REF LO E1 8 F1 6 COM 31 IN HI .01: 61 7 A2n2 = 30 IN LO 0-- 82 11 CREF 01L 34 IC1 7106 C 10 9 02 E214 F213 38 OSC3 100pF: = 100k 62 25 A3 23 39 l,o OSC2 B316 4o OSC1 29 A/Z ... o.47: : *47k *SEE TEXT 28 BUFF 0.22:: 27 INT BP 121 TEST 37 29 C3 24 11 03 15 10 E3 18 9 F3 17 31 63 22 32 K19 3 y 20 2 -!;6 l1 ~6 13 14 15 124 25 23 22 n1 na 1~ 120 21 r-e/ / / /- / 3-1/2 DIGITLCD A K _v_ K/ F/ 6 E,-::, ,-, ,-, •-OP3 OP2 •2 DP1• 1OP3 8 np? 12 DP1 16 1 38 39 40 +9V ,_J4 4070 ◄ 3-1/2 DIGIT PANEL METER 7 ~" - ~~ 5,- ~)1c2~ 6'8·- 4 fr--"~ _/ .... - ----=l~ 9· ' '-- 100k~ 100k3 100k Fig.1: the circuit is built around an ICL7106 3½-digit AID converter IC which has its digit & segment driver outputs linked directly to the LCD. XOR gates IC2a-lC2d buffer & invert the backplane signal to drive the decimal point. above a set threshold level. When the voltage falls below this threshold level, the counter is stopped. Because the capacitor discharge is linear (it forms part of an integrator circuit), the counter reading is proportional to the input voltage. It's then just a matter of scaling the reference voltage so that the reading is correct. The external components on pins 38, 39 & 40 set up the internal inverters to provide the clock signal. This clock signal controls the timing of the digital logic and is applied to the conversion section as well. When the output of the final comparator stage in the A/D converter is set, the 4-digit counter counts up at the rate of the clock frequency divided by four. When the comparator output is subsequently reset, the internal latch stores the current reading and loads it into the 7-segment de- coders and the LCD phase driver. The phase driver now supplies a square wave signal to the appropriate segments of the LCD. At the same time, a backplane signal is applied to the LCD from the divide-by-four output of the clock and a further divideby-200 stage. Circuit details Fig. l shows the complete circuit details. As you can see, most of the connections are between the 7106 IC and the 3½-digit LCD. ICl contains a number of inputs that can be varied to allow the meter to do different things. Of particular importance is the internal reference voltage (VREFL which is set by the external 15kQ resistor and trimpot VRl. The internal oscillator frequency for ICl is set by the lO0kQ resistor and the l00pF capacitor on pins 38, 39 & 40. These components give a clock frequency of approximately 48kHz, which produces a rate of three readings per second. In addition to the clock setting components, IC1 also requires three external components to set up the AID converter and provide the auto-zeroing function. The 0.47µF capacitor on 'pin 29 sets the auto-zeroing, while the 47kQ resistor and 0.ZZµF capacitor set the integration time constant for the AID converter. These last two components also set the noise immunity of the IC and should be changed for different full scale voltages. Decimal points Because the 7106 IC does not have the necessary drive circuitry to support the decimal points on the LCD, SEPTEMBER1992 79 ► Phone Your Order To Us Toll Free We guarantee our Jetservice Courier will deliver to 'your door faster than any other Australian supplier (including that local supplier just up the road). If we fail, I'll give you your money back plus $5.00 for your inconvenience. 2 Sector Alarm System Kit Here's a simple project that monitors the power drawn from a 'master' socket and automatica ll y switches o n a 'slave ' socket. It wil l monitor one or several appliances plugged into the 'master' and switch on o ne o r several devices plugged into the 'slave·. Ideal for Hi-Fi's or co mputers w ith peripheral hardware. K6070 $59.95 Solar Generator Kit (ET I Dec '87) Charge Your Batteri es Free Fro m , l ~· c The Sun. T he So la ~ Generator charges and maintains your standa rd 12V lead .· acid ca r battery via the sun. Ideal for boats, caravans and remote data acquisition stations etc . Must be used in co njunction with a suitable solar panel. Four Digit Combination . Lock Kit K 1925 $44.so (EA March/April '89) Features : • Includes 12V 1.2 Amp hour inbuilt sealed leadacid backu p batte ry • E.!sy to build , assembles on a single PCB • Two sectors delayed and insta nt inputs • Entry and ex it delay • Panic alarm input• Line monitoring • Soft pre alarm • Lamp te ll -tale output • Auxilliary relay for external siren etc • Key switch operation • Operates on vi rtua lly any type of sensor (SC Dec '90) This 4 Digit Combination Lock is bound to prove useful in many applications. Such as accessing alarm system s, e lectron ic doors, ignition ki llers or just about anyth i ng that comes to mind. Momentry or latched relay output. New 4-Channel Lighting Desk (SC June/J ul y '91) M■k• your at■ge production • profeulon■ I lhow with thla new Lighting Mixer. ldHI for amateur thHtre groupa band• etc. This 4-chan nel lighting desk is intended for theatre, disco and music group applications. It has heavy duty circuitry and is able to cope w ith spotlig hts rated up to 1000 watts or more. It has been designed and b uilt for the rigours of commercial use . You can flash each channel up to any brightness as set by the 'Flash Master' fader. Similarly, the 'Channel Master' cont ro l fades all lights up or down , to or from their individual fade settings. Two chaser faders co ntro l the rate and lamp brilliance when the unit is operated in chaser mode. The lights can be flashed to fu ll brilliance or to an intermediate setting as set by the 'Chaser Master' K1910 $89.oo _. 4 Channel Guitar Mixer & Preamp Kit K1680 $13.95 (SC Jan 1992) T his project takes advantage of the ~~:~~w fader. ... low cost •· . •· •i• · •· ••• ,. ,. • .-.-11P1- rw, ""'B ,,,...a'"'b _ y.....,R ,,,...o_o _m _""'M ,..,,..o - n""'i""'t_o_r_-4 ;~~~~~i "ltter features separate bass, midrange and & FM Transm trebel controls, very low noise and Kit a: ~~ -. 0 OABVAOOM This Baby Room ~QN.!JO_ R Mon itor all ows you to liste n to your baby from a remote location using a conventional FM receiver. It runs from a sing le 1.SV AA battery and incl udes a muting facility so that it only transmits sounds above a certain level. K 1180 .95 $ 24 Ni-cad Battery Discharger Kit Designed to rid yo ur ni-cad batteries of the 'memory effect' and rega in fu ll re -charge pote ntial. It discharges your nicad batteri es correctl y to enable a fu ll and p roper re-charge. Suits most battery packs. Great for mobile phones, rechargeable dr ills, re m ote co ntro lled toys etc. K1640 $24.95 I i:~~o~t~o~~t;t1a1r:::1i~g~:r~~~T~i~,n,~~ ~se with most musical instruments from keyboards to guitars to tape decks. In fact, you can feed it with just about any audio signal - it's not just lim ited to gu itar outputs. K5535 $49.95 Transistor Tester Kit K5815 Normally $3?,0'.'oo T h is Month $299 .00 Playmaster "Pro Series One" High Power Mosfet Amplifier Kit (EA Dec '89/ Jan '90) K $599 5070 This design has been carefully developed to produce a high definition audio output with reliability, ease of construction and low cost. Kit comes complete with all components, toroida l tra nsforme rs and case. Features: • Individua l toroidal transformers for each channe l f:Jr low residua l hum • Mosfet tec hno logy for ultrahigh performance• Power Output of 140W RMS into 8 Ohms. Studio 200 Stereo Control Unit Kit (SC June/ Ju ly '88) K5015 $229.oo Outperforms Commercial Unit• Coating $600 Or Morel The Studio 200 features slim 1u rack mount profile. treb le, stereo mono switch and volume control. Inputs include phono, tuner, VCR and tape loop. Ideal mate to K 5070 Amp (EA Aug '83) Checks transistor in circuit. " No need to unsolder suspect transistors". Have you ever de-soldered a suspect t ransistor, on ly to find that it checks out OK? Features: • Tests both NPN and PNP transistors in c ircuit at the touch of a switch • Tests Diodes and SCRs as well • No need to switch between NPN and PNP - it's automatic • LED indication to show co nditio n of device. Th is Digital Recorder delivers astonishing ~,:.::.~:.:,.:;::;;..;;.:;:.:"------, reproductio n of vo ice and/or music without any movi ng parts. It can store 4 different 30 second messages or 1 recording up to 2 mi nutes . Typical applications include • Alarm system messages • Sales messages for customers put on 'hold' • Talking Displays for shops • Emergency warning messages • And countless other applications where voice or music is required • K 9550 PCB alone version• K9555 Inc ludes fully punched & screen printed inst rument case. K253o$17.5o K9550 Adjustable 0-45V, 8 Amp Bench Power Supply (SC Jan / Feb '92) K 3360 $375 .00 Using state of th e art circ uitry this supply wi ll be a great asset to the enthusiast and professional ali ke. It uses switc h mode principles wh ic h allows fo r smaller transfo rmers, and heatsi nking wh ic h means greater efficiency, less heat and lighte r weig ht. feature,: • Var iab le output • Variab le cu rre nt limit • Separate Earth Terminal • Individual Volt and Amp Meters• Constant 13.8V setting• Short circuit proof Speclflcatlona: • Output voltage 0-45V • Output current BA <at>35V, 6A .<at>. 40V • . Load regulation 1% • Ripp le and Noise 40mVp-p at 8A 35V • Current lImIt 800mA8.6A • Over c urre nt limit 9A • Fold back c urrent less than 2A Digital Voice Recorder Kit PCB Format $129.95 K 9555 With Laboratory Power Supply (EA May '85) Instrument Case K 3300 $149.95 $195.oo 3-50 Volta at up to 5 Amp• This supply has been one of our most popular. It includes the latest refinements and is now housed in a tough 'A BS' instrument case. This compact version uses a high efficiency toroidal transformer resulting in less heat and weight • Exclualve to Altronlca • Deluxe instrument case • Attractive silk screened front panel • Pre-dri lled and punched chassis - No holes to d rill • Front panel drilled fo r K3302 option . Speclflcatlona: • Output Voltage: 3 to 50V • O utput Current: 5 AmP,s Max • Floating Output • Ripple: less than 5mV • Dual Meters 10 Turn Pot For Precision Voltage Control Option K3301 $4.so Fixed +/-12V Rai ls lndepe ndant of Main Output K3302 $14.50 Famous Get 240V AC from your ca r, truck or boat battery. The Al tron ics range inc ludes an inverter for nearly every application . Fantas ti c for camping . boating, farms and anywhere else 240V AC isn 't available. Each size in verter is available in kit form or fully built and tested . The 300 and 600 Wat t Inverters now feature new improved circuitry usi ng multiple mosfet outputs making them even more reliable with a genuine 300 or 600 wattC ontinuous power rati ng. Our latest model, the 1200 Watt Powerhouse offers excellent va lue fo r money and pe rformance. It features crystal locked c ircuitry and a massive 2400 watt power surge making it ideal for smal l fridges. vacuum cleane rs, power too ls etc. Any model an absol ute necessity where 240V isn't available. Cal l Altronlca today for more informati o n on freeca ll 007. 008 999 300 Watt $279 K 6755 Built-up $379 K 6750 Kit Version These k its use quality Vita speakers made in Denmark and specially engineered enclosures for optimal performance. Black wood grain veneer make them ideal for any decor and situation. These two way models include high grade crossovers, speaker terminals and removable front grille. Simpl~ construction with only basic tools and skill required. These kits are complete a:,d incl ude speal<.er cloth, damping materia l, grille clips, speaker term ina ls, screws and parts. Outstanding performance for the fraction of the cost of commercia l equ iva lents . VIFA SA-50 2 Way Bookshelf System, 50 Watts RMS Now Only w,oe. I ...,.. $299.oo pr Jip.t'I';,:iJ' Powe1tH01.1s!" ~ 600 Watt " $499 K 6770 Kit Version K 6774 Built-up 12V Input K 6775 Built-up 24V Input $ i -,:~ • ~ ... ,"'-'c. ._, ~ I ' \ , \ ' -' Normally $ 7 ~ o 1200 Watt $799 K 6792 Bui!t- up 12V Input $999 K 6793 Built-up 24V Input K 6790 Kit Version Now Only $699.oo pr ..•----.:.= = =:!...---------1 Stereo Extension Ceiling Speaker Kit Want a set of high grade extension speakers for the back patio, games room, den, workshop, kitchen? Well here at Altronics we have put together this great kit which includes speakers, grilles, cable, screws and even a wall mounted volume contro ller. The speakers are our high qua lity 4" C 0626 dua l cone drivers, with stylish wh ite gril les - ideal for mounting in the cei li ng. Volume contro l mounts in standard electrica l wa ll box and includes 6 volume settings as well as off. Includes 2 x 20m cable. 300 Watt Economy Inverter Turn 12V DC lo 240V AC. This fantastic inverter wi l l power lights, TV's, A fine dri ve r using only high quality components and techno logy. For example barium ferrite magnets, revolutionary Kapton voice coil and unique c arbon fibre cones. C 0988 Normally $9J'6o. Now Only $69.oo 3034 $ This Month Only Weather Proof Monitor and Sound Column Speakers This fantastic new range of monitors and columns just have to be heard to be believed. Designed by the Altronics engineer team with extensive consultation from audiophiles and architects, these speakers are absolutely ideal for hi-fi extensions and P.A. Constructed from rugged extruded aluminium and UV resistant plastic makes these units both weatherproof and built to last. The drivers used are 4" carbon fibre with an inbuilt coxial tweeter. Ported design makes bass response incredibly smooth and deep. Two sizes available, 30 and 60 watts RMS, in a black or white powder coat finish. Mounting these speakers are made easy by employing the new "Wacki " bracket system. Call Altronics today for a free colo u r brochure. Proudly Ma.de in Australia 30 Watt Monitor Serles Normally $23fr6o ~,._,,s $169.oo ea ,io 0924 8 Ohm White !149 .00 ea 60 Watt Column Serles Vo lt Line Wh ite $2 $160 0928 .00 ea CC 0936 0937 100 100 Vo lt Li ne Black 45 .00 ea Audio Frequency Generator RF Signal Generator This new bullet tweeter looks and sounds great . Genuine Motorola KSN 1165A. Features 400 watt max imum po wer capability frequency response 1.BkHz to 30kHz and SPL at 93dB (2 .83v/ 1 m). 91 x 91 mm mounting hole centres. Specifications available on request. Simply wires in paralle l to your woofer. No crossover or capacitor required. As it presents al most no load to your amp it doesn't effect the overall speaker system's impedance. Fantastic for hi-fi or disco speakers. C C 0925 8 Ohm Black C 0927 100 Vo lt Li ne hite C 100 Vo lt Li ne Black a 1540 Normally $3~.oo Now $25O.oo .• Motorola Piezo Tweeter M 8120 Output Level: Sine: 8V rms Square: 10V P-P Output Attenuator: -20dB, -40dB and fine adjust - 59.ss These Poly Emulsion Coated Cone I PECC) woofers offer excel lent quality and performance. With a max imum power rating of 200 watts or 120 watts continuous and a frequency response down to 30Hz these drivers make an ideal sub-woofer or rep lacement bass speaker. Massive 2.5kg nett weight. See Altronics ·92 catalogue for full details . c 3032 Waveforms: Sine/ Square ' (/ fibre these speakers are ideal for boats an automotive use . Max input power 70 watts or 30 watts RMS. Resonant frequency 65Hz. See Altronics '92 catalogue for full details . C Normally $ 8 ~ T~ is Month Specifications: Frequency: 10Hz - 1MHz Accuracy: +/ -3% + 2 Hz Output C ~e~7;t~~~ ~:r~~~u~~g~f:!~~on I 625 tools, electric shavers and a whole host of other appliances. Great for camping, out in the bush and any place where 240V is not avai lable. Features: • Complete with over current circuit breaker• Fused 240V output• Built in panel meter to monitor output vo ltage • panel meter to monitor output voltage • Strong steel case and chassis. pf\\C1' fflO f>.' 1 800w•uoe,.. c,it~.,,., -::::, Si ... We have a huge ~~:lus of Vila C13WG-08-08 woofers. These quality drivers offer . high performance in both • . ported and sealed ,, enclosu res. Exceptionall y smooth response useable up to 5kHz. Caref ul desig·n and construction us ing rubber surround makes it possib le to obtai n an amaz.ing 50 watts RMS power ca labicity. Fa ntastic replacement or new construction speaker. C 3110 Normally $~00 Now $49.oo 6.5" Carbon Fibre · , 1,;.Jf>.l\.ft{~S Woofer r,10' C 0£ S Normally $3~oo pr Many Hundreds of Altronics l!7v~rters Now in use Australla ~~o~;•r sAvf:0°1,0· ., With provision for internal and external modulation. Specifications: Frequency Range: l00kHz - 150MHz in 6 ranges RF Output Level: 100mV rms Accuracy: +/ -3% Modulation: • Internal (30% depth): 1kHz • External : 50Hz-20kHz • Crystal Locked Oscillator Q 1550 Normally $ ~.00 Now $225.oo C 6160 $39.95 Proudly Made In Ausrralla Yet another Altronics innovation , proudly designed and made in Australia . These great new speaker mount brackets simply screw onto the wall and speaker allowing a universal 50° angle of adjustment . Su itable for speakers up to 5kg . No special tools required. Available in white or black. A must for any extension speaker. H Wh ite H Black pair 8010 8012 $39.95 Universal Battery Chargers High quality computer fans ideal for power supplies, amplifiers, computers etc. Reliable Sun non brand. Full . range available for almost any application. As a result of a bulk scoop purchase, we are able to offer to you these fantastic universal Ni-Cad t3attery chargers at a more than ridiculous price' It will charge any combination of up to 4 of AAA, AA, C or D size~batteries at one time plus a 9V. Features a LED indication to show each battery has made an electrical contact. Also has an added bonus of a battery tester function. Hurry. Stoc•s limited. Definately no back orders. 5 This Month Only $19.95 LID NOT SHOWN Passive Infra-Red Flood Light Control Just arrived , this new model PIA floodlight activates when it detects movement of a person or car approaching. Great to welcome visitors, ward off intruders or even to find the keys in the dark! Features daylight sensing circuit which means unit will not activate during daylight hours (save on your power bil l). Includes manual override facility to turn lights on continuously or automatically. Features . movement sensitivity adjustment, and turn on period. Great for the driveway or backyard. Complete with two screw in type sockets for standard 150W floodlight globes (not included). Amazing Value on Deleted UHF Alarm This UHF system contains one receiver and 3 wireless reed switches for doors and windows etc. T he ma,n controller simply plugs into 240V, the remote, reed switches are attached to your door/window frames and presto, the alarm is installed! Simple push button operation, 4 digit user selectable on/ off code, built-in siren makes this unit a pleasure to use. Includes 12V 1.2Ah backup battery and 9V batteries for remote reed switches. Because there is no need to drill holes in the wall or ceiling, making this unit just great for rented flats or units, or for those who don't want the trouble and hassle of a wired system. Also ideal for boats, caravans, the shed, garage or granny flat. Take the unit with you if you move - no wasted time and money. Remote Car Alarm 1020 80mm' $22.25 F 1030 120mm' $24.25 F 12V DC Model 30 Amp relays with individual fuses. Great for car headlights, spotlights etc. I S4335 Normally $1~o This Month Only $9.95 Chassis Mount RCA Sockets Australia Post. Allow approx 9 days from day you post order to when you receive goods. OVERNIGHT JETSERVICE Up to 3Kg is $10.00, 3Kg to 5Kg is $23.00 - We process your order the day received and despatch via . Overnight JetHrvlce Courier for delivery next day Country areas please allow additional 24-48 hours. PX f! 0235 Normally $3,..116 $1.50 Universal Remote Control PA This Month Only This universal infra-red remote control makes all other remote units superfluous. Will control CD players, videos, TV's and stereos etc. Controls up to 6 different appl iances. Easy to use and programme from an existing functional remote. 1000 $69.s5 Blank Rack Panels S'3" STANDARD DELIVERY I PACKING CHARGE $3.50 to 500gms, $5.50 500gms - 1Kg, $8 1Kg-5Kg AUSTRALIA WIDE - We process your order the day received and despatch via. These terminal blocks are ideal for 240V, speaker or DC voltage termination. Can be cut into shorter strips. Raised base for extra voltage protection. 3 rows of stereo (left and right) sockets. High quality. Bargain price. loud siren and visible warning of flashing headlights when the alarm system is triggered. Keyring remote control allows arming with 'beep' sound and disarming with headlights flashing signal. The alarm system will be triggered by unauthorised entrance through the car doors, boot, bonnet or removal of the car sound unit. The siren will sound and the headlights flash for 60 seconds. Ea■ y to ln1tall. S 4LTilOnlC.) Finger Guards ~i A 174 Roe St. Perth W.A. 6000 Phone (09) 328 1599 PHONE TOLL FREE 008 999 007 MAIL OROERS C/- P.O. Box 8350 Stirling Street PERTH W.A. 6849 1040 120mm' $23.so F F 1022 80mm $2 F 1032 120mm .45 1050 80mm' $17.50 Sturdy Spotlight 12 Way WireProduc:t Terminal Relay Blocks Includes two separate F With WlreleH Remote Control Audible warning with a 125 decibel 5220 $99 .00 24V DC Model 240V Models 2110 Normally$~ $3.50 or 10 up $3.oo Now Only Stationmaster CB Base Antenna earthed or unearthed. • 50 any height above the ground, Ohm impedance• V.S.W.R. 1.3:1 • Height 5.6m • Power 1kW L All $8.00 H 0422 Natural Aluminium H 0432 Grey H 0435 Black 1 . r· !.·,.· 3215 Normally $11 ~ $99.oo This Month Only Top quality blank panel clearout. All stock must go at these crazy prices. Stock is limited with definately no back orders at these prices. 2 unit - I Extra wide bandwidth base antenna without ungainly size. Supplied with a fully pre-tuned and assembled DC grounded matching system and all mounting hardware. Waterproofed and useable at 3 Unit - All $12.95 H 0423 Natural Aluminium H 0433 Grey • HEAVY HEAVY SERVICE - All orders of 10Kgs or more must travel Express Road Please allow 7 days for delivery. $12.00 to 10Kgs. $15.00 over 10Kgs. INSURANCE - As with virtually every other Australian supplier, we send goods at consignees risk. Should you require comprehensive insurance cover against loss or damage please add $1.00 per $100 of order value (minimum charge $1 ). When phone ordering please request "Insurance" TOLL FREE PHONE OROER - Bankcard, Visa, Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight JetHrYlce we deliver next day. AL TRON ICS RESELLERS Chances are there is an Altronic Reseller right near ct1eck this list or phone us for details of the nearest dealer. De ■ lero are highlighted with a ■ These dealers generally carry a comprehensive range of Altronic products and kits or will order any required item for you. you - Blue Ribbon WA COUNTRY ALBANY BP Electronics ■ (098) 412681 Micro Electronics (098) 412077 BUNBURY Micro Electronics (097) 2162:!2 ESPERANCE Esperance Communications (090) 713344 MANDURAH Lance Rock Retravision (09) 535 1246 PORT HEDLAND Ivan Tomek Electronics (091) 732531 ROCKINGHAM TV Joe's (09) 5271806 NT ALICE SPRINGS Farmer Electronics (089) 522388 DARWIN Ventronics (089) 853 622 VIC All Electronic Components (03) 6623506, TECS (03) 6706474 BORONIA Ray Cross Electronics ■ (03) 762242~ CHELTENHAM Talking Electronics (03) 5842386 COLLINGWOOD Truscott Electronics (03) 4198208 CROYDON Truscott Electronics ■ (03) 7233860 FOOTSCRAY G.B. Telespares (03) 3179100 PRESTON Preston Electronics ■ (03) 4840191 COUNTRY BAIRNSDALE LH & LM Crawford (051) 525677 BALLARAT Ballarat Electronics (053) 311947 QLO Del sound PL ■ (07) 8396155 WEST END BAS. Audiotronics (07) 8447566 WOODRIDGE David Hall Electronics ■ (07) 8082777 COUNTRY GLADSTONE Gladstone Electronic Services (079) 724459, Electronic Enterprises (079) 726660 MAROOCHYOORE MALS Electronics ■ (074) 436119 MARYBOROUGH Keller Electronics (071) 214559 NAM BOUR Nambour Electronics (074) 411966 PIALBA Keller Electronics (071) 283749 ROCKHAMPTON Access Electronics (East St.) (079) 221058 TOWNSVILLE Super Solex ■ (077) 724466 SA Force Electronics ■ (08) 2125505 BRIGHTON Force Electronics ■ (08) 3770512 CHRISTIES BEACH Force Electronics ■ (08) 3823366 FINDON Force Electronics ■ (08) 3471188 HOLDEN HILL Force Electronics ■ (08) 2617088 LONSDALE Force Electronics ■ (08) 3260901 ENFIELD Aztronics ■ (08) 3496340 COUNTRY WHYALLA Eyre Electronics (086) 454764 TAS HOBART George Harvey ■ (002) 342233 LAUNCESTON George Harvey ■ (003) 316533 NSW David Reid Electronics ■ (02) 2671385 REVESBY Revesby Electronics (02) 7922295 SMITHFIELD Chantronics (02) 6097218 COUNTRY COFFS HARBOUR Coffs Habour Electronics (066) 525684 NEWCASTLE Novocastrian Elect.Supplies (049) 621358 WARNERS BAY Vilec Distributors (049) 489405 WINDSOR M & E Elect. and Communications (045) 775935 WOLLONGONG Newtek Electronics ■ (042) 271620, Vimcom Electronics (042) 284400WOY WOY Alphatran Electronics (043) 434919 we've added our own circuitry so that you can select the required decimal point via a switch. Let's see how this works. The backplane (BP) signal on pin 21 is fed to IC2d, which is a single dual-input XOR gate. This stage simply functions as a buffer. Its output at pin 11 is in phase with the backplane signal and drives gates IC2a, IC2b & IC2c, which are connected in parallel as a single inverter stage. These parallel inverters produce a square wave which is complementary to the backplane signal and this then drives the decimal points of the LCD via one of three linking options. Alternatively, you can use a single pole 3-position switch for decimal point switching. and REF LO pins) would be set to 0.316V. Current measurements o.47 ,ooiF ...::~~,~~s t .01 f 0 ~ DP2.,._..::,_ □P1,► -1-,~--® ggg ~ -~I ~ -~- F - _..: ~ - 10uF O· ~~ Voltage measurements In order to use the module as a 0200mV (actually, 0-199.9mV) voltmeter, VR1 is set so that the reference voltage between pins 35 & 36 is 100mV. The decimal point connection is made from the output of the paralleled inverter stages to pin 16 (DP1) of the LCD. For a 0-2V (0-1.999V) meter, VR1 is adjusted to obtain 1.000V between pins 35 & 36 and the RC values on pins 28 & 29 are changed to 470kQ and .047µF. The decimal point connection is now made to pin 8 of the LCD (ie, to DP3). In both cases, all other parts to the left of the 1MQ resistor on pin 31 are deleted, except for Ryl which is made equal to 10Mil This 10MQ resistor ensures that the display returns to 000 when the input is removed. Higher voltage ranges are obtained by scaling the input using voltage divider resistors Rxl, Rx2, Ryland Ry2. For example, a 0-20V range can be obtained using a 10:1 voltage divider. We can do this and at the same time obtain a 1MQ input impedance by ~ ~ •3 •2 ·•1 INPUT - + • • 9V BATTERY --------' Fig.2: be sure to install all the wire links before mounting any of the other parts. Resistors Rxl, Rx2, Ryl, Ry2 & RA are selected from Table 1. making Rx (ie, Rxl/ /Rx2) = 900kQ and Ry = 100kil The decimal point connection is made to DP2 (pin 12) of the LCD, so that we get a full-scale display of 19.99V. Table 1 lists the resistor values for several other ranges up to 200V. In some measurement situations, it will be necessary for the meter to display a full-scale reading (ie, 1999) for some specific input voltage. Instead of using a divider network, this can be achieved by setting VREF to half the full-scale input voltage using VR1, provided that the input voltage is less than 2V. For example, let's say that a voltage of 0.632V from a transducer is required to give a reading of 1999 on the LCD. In this case, the reference voltage (ie, the voltage between the REF HI To give the meter added versatility, we've also left space on the PC board for 5W shunt resistor RA to allow the meter to read currents up to 2A. The way in which this works is quite straightforward. Resistor RA is wired in parallel with the inputs, while resistors Rxl, Rx2, Ryl & Ry2 are all deleted. If RA = 0. H2, 200mV will be developed across the resistor when the current through it is 2A. This voltage is then applied to the meter which is set up for the 200mVrange (ie, VR1 is set for 100mV between pins 35 & 36). At the same time, DP3 (pin 8) of the LCD is connected to the inverter outputs, so that the meter reads 1.999A full scale. The reason that you should choose the 200m V range is to limit the power dissipation in the shunt resistor for any given reading. For example, at the maximum reading of 2A, the power dissipation is P= I2 R = 2 x 2 x 0. 10 = 0.4 W. This figure is well within the resistor's 5W rating. Another reason to use the 200m V range for current measurements is to limit the "burden voltage" of the circuit. This is subtracted from the supply voltage to the external circuit and naturally, this reduction should be as small as possible. Note that because of the tolerances of the shunt resistor, it may be necessary to adjust the reference voltage in order to get the correct reading. For example, if the shunt resistor has a value of 0.090, then we will only obtain a voltage of 180mVacross it for a current flow of 2A. This means that the meter will only read 1.800 instead of 1.999 unless VREF is adjusted to 90mV. In practice, VR1 is adjusted so that the meter displays the correct reading for a known current. Power requirements TABLE 1 Range Rx1 Rx2 Ry1 Ry2 RA Decimal Vref 200mV - - 10M - - DP1 100mV 2V - - 10M - - DP3 1V 20V 1.8M 1.8M 100k - - DP2 1V 200V 1.8M 2.2M 10k - - DP1 1V 2A - - - - 0.1 ohm DP3 100mV Power for the unit comes from a 9V battery and this is decoupled using a 10µF capacitor. It directly supplies the two ICs and the voltage divider network (15kQ and VR1) that's used to set the reference voltage. In operation, the common input (pin 32) always sits 2.8V below the supply rail, which means that the reference voltage stays constant as the battery disSEPTEMBER 1992 83 PARTS LIST 1 PC board, code SC04110921, 120 x 71mm 2 32-way SIL sockets 1 10kQ miniature horizontal trimpot Semiconductors 1 7106 3½-digit AID converter (IC1) 1 4070 quad XOR gate (IC2) 1 3½-digit LCD (Altron ics Cat. Z-7297) Capacitors A more compact assembly can be achieved by cutting the PC board into two sections & then soldering these sections together at right angles. Alternatively, you can connect them together via a short length of rainbow cable. There is also sufficient room on each section for extra mounting holes, if necessary. charges. Alternatively, you can power the unit from a plugpack supply or from the equipment being monitored. In any case, the maximum supply voltage should not exceed 12V. The current consumption of the unit is about lmA. Construction All of the components for the 3½Digit Panel Meter are mounted on a CAPACITOR CODES 0 0 0 0 0 0 0 Value IEC Code EIA Code 0.47µF 0.22µF 0.1µF .047µF .01µF 100pF 470n 220n 100n 47n 10n 100p 474 224 104 473 103 101 single PC board coded SC04110921 and measuring 120 x 71mm. This board has been designed so that it can be cut just below the LCD and the two pieces soldered together at right angles to make a more compact unit (see photo). Alternatively, the two pieces can be connected together via a short length of rainbow cable. There is also sufficient room on each section of the board for extra mounting holes, if necessary. Before beginning construction, check the board carefully against the published pattern for any shorts or breaks. If you do find any faults, repair them immediately before installing any of the parts. Fig.2 shows the parts layout on the board. Begin by installing the wire links - there are 15 in all plus an extra link for the decimal point option. These links should all be flush with 1 10µF 16VW electrolytic 1 0.47µF 63VW MKT polyester (.047µF for 0-2V meter) 1 0.22µF 63VW MKT polyester 1 0.1µF 63VW MKT polyester 1 .01 µF 63VW MKT polyester 1 100pF ceramic Resistors (0.25W, 1%) 1 10MQ (5%) - see text 11MQ 4100kQ 1 47kQ (470kQ tor 0-2V meter) 1 1SkQ 1 0.1n SW (RA - current meter only) Note: see Table 1 for values of Rx1 , Rx2, Ry1 & Ry2 Miscellaneous Solder, tinned copper wire for links, 9V battery the board and must be straight to avoid accidental shorts. You can straighten the link wire by clamping one end in a vyce and then stretching it slightly by pulling on the other end with a pair of pliers. When all the links are in, install the resistors, trimpot and capacitors on the board. Table 1 shows the resistor values for the various voltage and current ranges, plus the decimal point RESISTOR COLOUR CODES 0 0 0 0 0 0 84 No. Value 4-Band Code (1%) 5-Band Code (1%) 1 1 4 1 1 10MQ (5%) 1MQ 100kQ 47kQ 15kQ brown black blue gold brown black green brown brown black yellow brown yellow violet orange brown brown green orange brown not applicable brown black black yellow brown brown black black orange brown yellow violet black red brown brown green black red brown SILICON CHIP IOa~~~~ sc.... Never push down on the centre of the display - you may damage it if you do. You can determine the orientation of the display by angling it so that the reflected light shows a faint image of the digits. There is also a small ridge in the glass on the lefthand edge of the display. Finally, connect a battery snap connector to the board. The unit is now ready for testing. ~«;,;-;.-;--- 0_41_10....9~2~1 Fr..:~).=" 0 ~~~0 E~I i~~ IO a ""ci'O J> GO Testing SILICON CHIP 1992 Fig.3: the PC board is coded SC04110921 & measures 120 x 71mm. Check your board carefully against this full-size pattern before mounting any of the parts. ticularly that the ICs face in opposite directiqns on the board. Take care when installing the LCD panel because it's easily damaged. Check that it is correctly oriented and that all pins line up with the sockets before gently pushing down on the corners of the module. linking details. If you build the unit as a current meter, mount 5W resistor RA slightly proud of the board so that the air can circulate beneath it for cooling. The ICs can now be installed and two 20-pin SIL sockets soldered into position to accept the LCD. Note par- To test the unit, just snap the battery into place and check that the display turns on and settles down within a second or so to "000". If you don't get this, switch off immediately and check for assembly errors. For example, if you get incorrect segments appearing on the LCD , check the board carefully for shorts between the ·tracks underneath the LCD and ICl. Finally, note that if you are using a voltage divider on the input (ie, for voltage ranges greater than 2V), then the two outer pins (1 & 3) are used for the input. Ifno resistor is used for Rxl or Rx2 , then pins 1 & 2 are used. SC IAN J. TRUSCOTT'S ELECTRONIC WORLD 30 Lacey Street, Croydon, 3136. Phone (03) 723 3344; Fax: (03) 725 9443 Now also at: 200 Smith Street, Collingwood. Phone (03) 419 2808 Mail & Credit Card Orders Welcome *** SAVE ON OUR SEPTEMBER SPECIALS Exclusive to SILICON CHIP readers: *The Portasol Professional Soldering Iron* Normally $79.95. This month *** Cordless, Refillable Butane Gas-Power'd Soldering Tool Kit $67 .50 Safety Stand Hot Knife *PLCC Extractor Tool* PLCC Extractor prevents damage: th is new J-lead IC remover has a dual action to protect fragile PLCC packages when being extracted from carriers. First, its two steel fingers are inserted at diagonal corners of the package. Then, as hand pressure is applied, the steel fingers lock under the PLCC body. Finally, as further hand pressure is applied, the steel fingers apply a balanced upward pull to remove the package without damage. Normally $22.95. This month $17 .95 Cleaning Sponge Blow Torch accessory Hot Blower accessory Ask about our great range of kits & TV antennas SEPTEMBER1992 85 AMATEUR RADIO BY GARRY CRATT, VK2YBX Build this relative field strength meter It is often said that simple is best. This simple relative field strength meter can be built in less than an hour for just a few dollars. One simple yet quite useful instrument that should be part of every amateur radio "shack" is a field strength meter. Such a device can be used to check the operation of a transmitter, regardless of the frequency band. Simple relative signal strength indications can also be used to evaluate the efficiency of antennas and the output stage of transmitters. Our unit, by necessity, is broadband. Most published designs are quite insensitive, relying solely on the rectifi- . cation of RF using a small signal diode. The resultant DC voltage is then filtered and used to drive a DC meter. Fig.1 shows this typical arrangement. To overcome this shortcoming, we have added an LM358 operational amplifier, which is used to amplify D2 DCNIDEO OUTPUT Fig.1: basic circuit for a field strength meter. The filtered output appears across C2 & can be coupled to a DMM. the rectified RF voltage. Also, we decided that because most amateur operators have a digital multimeter, we would use this as the indicator. Fig.2 shows the final circuit. Of course, virtually any op amp capable of single supply operation could be used. The RF field applied to the antenna induces a voltage across the terminating resistor Rl. This voltage is rectified by diode Dl, which is a germanium or Schottky diode. Resistor R2 and capacitor Cl filter the resulting DC voltage, while Cl also bypasses The circuit is assembled onto a small PC board & this is plugged into a digital multimeter via two banana plugs to obtain the relative signal strength readout. 86 SILICON CHIP pin 3 of the op amp, thus preventing RF energy from being coupled into the input. The DC amplifier we chose is an LM358, with an adjustable gain ofup to 101. This is set by VRl, a 100kQ potentiometer. If additional sensitivity is needed, then the bias arrangement shown in Fig.3 can be used. Here, a small amount of bias is used to almost turn the diode" on", thus overcoming most of the 0.25V drop characteristic of germanium diodes. The output of the op amp is fed via current limiting resistor R4 directly to the input of the DMM. By selecting the 200mV scale, the multimeter can be used as quite a good indicator. In fact, it is possible to drive the meter to read several volts and if the DMM is autoranging, then so much the better. Power for the circuit is derived from a 9V battery. Diode DZ has been included to ensure that the incorrect polarity can never be accidentally applied to the op amp. Construction Our prototype was built on a small PC board (code SC06110921) but there's no reason why you cannot assemble yours on a small piece of preetched circuit board (available from most electronics stores). Fig.4 shows the parts layout on the PC board. The ideal mounting arrangement would be in a metal box, large enough to accommodate the 9V battery and an on/off switch. The output plugs should protrude through one end of the case and be positioned so that they plug straight into the "banana" input sockets of the DMM. The only critical component is Cl, which should be located as close to the antenna terminal as possible. Apart from that, the usual precautions when ANTENNA Fig.2: the final circuit uses D1 to detect the incoming RF signal. The detected signal is then filtered and amplified using op amp IC1. D1 protects the op amp against reverse connection to the battery. w 1 D1 c2 OA~5. or s1m. _047 c, .oo,I 7 .,. 7 Protect your valuable issues Silicon Chip Binders OUTPUT TO DMM VR1 100k RJ 1k .,. RELATIVE FIELD STRENGTH METER ··-+ . M G~ ~ LI ANTENNA fl 02$ .041W +9V-----... TO 1 ANTENNA- -i 1 -.111.:_ OUP~TTO DMM ------• ..._.,. E::!).001 .- {il'D- ..ffiD. .~ Fig.4: install the parts on the board as shown here & be careful not to confuse diodes D1 & D2. R1 Fig.3: this modified circuit provides greater sensitivity by applying forward bias to the detector diode. working at VHF and UHF should be observed; ie, all component leads should be kept as short as possible. The entire circuit draws less than 2mA when fully driven, so battery life will not be a problem. The antenna should ideally be telescopic, so that it can be adjusted in length (corresponding to a quarter wavelength) to suit the freque!lcy of interest. Alternatively, you can use an insulated PARTS LIST 1 PC board, code SC06110921, 51 x 30mm 2 banana plugs 1 battery snap connector 1 9V battery Semiconductors 1 LM358 op amp (IC1) 1 OA95 germanium diode (D1) 1 1N914 silicon diode (02) 1 100kQ trim pot (VR 1) Capacitors 1 .001µF ceramic capacitor (C1) 1 .047µF ceramic capacitor (C2) Resistors (0.25W, 1%) 1 12kQ (R1) 1 1kQ (R3) 1 4.7kQ (R2) 1 1.5kQ (R4) These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers & are made from a distinctive 2-tone green vinyl. They hold up to 14 issues & will look great on your bookshelf. * High quality * Hold up to 14 issues * 80mm internal width * SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A 11.95 plus $3 p&p each (NZ $6 p&p). Send your order to: Fig.5: this is the full-size pattern for the PC board. wire lead for the antenna (again cut to the appropriate length). The length of the antenna can be easily calculated using the formula L = 7140/F, where L is the calculated length in centimetres and F is the frequency in MHz. For example, if F = 400MHz, then L = 7140/400 = 17.85cm. At frequencies lower than UHF, the quarter wavelength must be significantly increased to compensate for the n egligible groundplane afforded by the case and the meter body. A larger metal case would partly overcpme this but this may not always be convenient. Our prototype showed good sensitivity and detected a 5-watt VHF handheld transceiver at a distance of 30 metres. We also checked the unit using both cordless and cellular telephones, with good results. SC Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. Use this handy form l ----------Enclosed is my cheque/money order for $_ __ or please debit my O Bankcard O Visa O Mastercard Card No: Card Expiry Date _ _/_ _ Signature _ _ _ __ _ __ _ Name _ _ __ _ _ __ __ Address_ _ _ _ _ __ _ __ _ _ _ _ _ _ _ P/code _ __ .. _ _ _ _ _ _ _ _ _ _ _ ,1 SEPTEMBER1992 87 The Story of Electrical Energy, Pt.20 One year after Sydney's Ultimo power station was built, the growing electric tramways had exceeded its capabilities. Massive extensions to the power house together with AC reticulation & AC/DC substations solved the problem. By BRYAN MAHER The Sydney electric tramway system had expanded so quickly by 1900 that voltage drop problems in the 600V DC feeders were acute. Both the Ultimo power station and the 600V feeder system were fast approaching their capacity limits. The 1900 figure of 100 electric tramcars running over the 50km of track 88 SILICO N CHIP was expected to be doubled almost yearly. An additional ten 600V DC feeders laid in 1901, reaching out eight kilometres from the power station, were only a bandaid solution. Massive extensions were called for, including a rethink of the whole system. As electrical technology was ad- vancing fast, it was decided not to build further DC generators but to adopt 3-phase AC. The designers, to their everlasting credit, decided to think big! A new engine room was called for, double in length, width and height compared to the original buildings. Plans were made and, in 1902, foundations were laid for six very large 2-cylinder vertical steam engines. Each was to be direct-coupled to a 1.5-megawatt AC generator. Each 2300 horsepower (1.72MW) engine was designed to supply a 50% overload for the 3-hour peak periods twice a day. By 1904, three of these engines were installed and running. The vertical 2-cylinder steam engines were single expansion cross- Facing page: this view of the Ultimo power house shows the three huge condensing steam engines and their alternators which rotated at 75 revs per minute. It must have been an impressive sight to behold. compounded condensing units. They towered 18.2 metres from top to bottom, although one third of this height was below floor level. That still left the top of the low pressure cylinder reaching 12.2 metres above the engine room floor. The rotors of the alternators were so heavy and so large in diameter that they did double duty as flywheels. The construction of each alternator started with an enormous cast iron flywheel 7.1 metres in diameter, with a rim 915mm wide. Forty DC magnetic field poles were then added around its periphery. These poles were built up of sheet iron punchings, insulated , and wound with 26mm x 3.175mm copper bar, wound on edge on an insulated frame. The 40 fieldpole windings were connected in series, resulting in a total field resistance of just 0.5-ohm. Measured over the field poles, those rotors were 8.85 metres in diameter. Each rotor weighed 98 tonnes without the slipring assembly. Add this to the 20-tonne crankshaft and you had 120 tonnes of machine parts flying around at 75 rpm. In fact, the peripheral speed of the rotors was 125km per hour - incredible figures for 90 years ago! In each machine, the rotor was mounted on the middle of the crankshaft, midway between the enormous cranks of the high and low pressure cylinders. The crankshaft, more than half a metre in diameter and over six metres long, was a massive piece of drop forged and machined steel. The high pressure cylinders were large enough at 813mm in diameter but the low pressure cylinders were enormous, with an inside diameter of over 1.6 metres. Each complete engine-alternator combination was undoubtedly the mightiest machine most Australians had ever laid eyes upon. Each one weighed a total of 450 tonnes. Three of these Allis-Chalmers-ReynoldsGeneral Electric engine generator sets The new alternators at Ultimo power station used up to the minute technology. Previously, all electric generation in Sydney had been 600V DC. Note the size of the low pressure steam cylinder. This had a piston diameter of 1.6 metres. were installed in Ultimo power station. Work had commenced on the building and the machinery foundations in early 1901 and all three machines were running under load just 29 months later, in May 1903, a truly remarkable performance! As the photos show, these machines were truly gigantic - the biggest machines in the southern hemisphere, in fact! Even to this day, the Ultimo engines numbers 5, 7 and 9 hold the record as the biggest reciprocating engines ever installed south of the equator. Interestingly, only three of the planned six machines were in- stalled because reciprocating engines were overtaken by new technology within a decade, New boilers To provide steam for the three new engi nes, 24 extra boilers were installed. These were housed in the boiler house extension, a giant structure which towered over the original buildings. They were Babcock, and Wilcox water tube boilers, each rated at 186kW (250 horsepower) and generating steam at 150psi (1.1 megapascals) and 240°C. These were a great SEPTEMBER1992 89 advance compared with the original units which were just three years older. Coal was fed to the boiler by a new invention, the automatic chain grate stoker. A small steam engine drove the stoker which effectively became the moving firegrate. Continuous movement of the grate finally tipped the spent ash and clinker down via a chute to ash trucks below. High above the boilers, an enormous bunker held 2500 tonnes of coal. Sixty boilers were planned, in two rows of 15 on each of two floors. Extra new pumps provided feed water for the boilers and circulating water for the engine condensers. The boiler house extension was done in two stages so that the old boilers could continue steam supply until half of the new units were installed. When the new southern end structure was completed and operating, the original boilers were demolished and the old boiler house extended vertically so that a complete matching facade was achieved. The extensions used 3-million 90 SILICON CHIP bricks to create a building 54 metres long by 30 metres wide. Near the middle of the south half of the boiler house, two giant new chimneys were erected, 69 metres high. Measuring 7.3 metres square at the base and 3. 7 metres internal diameter at the top, each chimney was capped by a 7-tonne cast iron crown. For the next 70 years, these structures dominated Sydney's western skyline. Coal brought from five different areas by tail way was crushed and then lifted by a chain elevator with 288 steel buckets to the storage hopper above the boiler room. Driven by a large DC motor through a reduction gear train, the elevator had a capacity of 40-tonnes per hour. High voltage alternators Not only were the alternators very large, they also produced very high voltages for the day - 6600 volts AC. The stationary armature coils were wound with square insulated copper (10.2 x 10.2mm), then insulated overall by nine layers of half-lapped 178 microns thick linen tape. Each layer This view of the Ultimo power station shows the alternators which were installed at a later date. Even so, the size the of the three original alternators and their condensing steam engines was never to be challenged. was baked, varnished and baked again, six times in succession. The 6kV insulation made by this simple method was reliable and long lived. Lead-sheathed oiled paper insulated cables of 3-core construction carried the current from the alternators to the 13-metre long switchboard. Sixteen panels of blue Vermont marble served the three generators, exciters and the original ten 6.6kV outgoing feeders. The high voltage circuit breakers were something new in Australia. A series of brick compartments lined with opalite had cast iron doors at front and soapstone slabs on top. Each such chamber contained one pole of a 6.6kV circuit breaker. Each pole consisted of two isolated sets of sprung copper contacts, arranged in pairs (like your thumb touching your first finger). To close the switch, a moveable copper bar of triangular cross section was raised to bridge all the contacts. The live moving copper bar was actuated by an impregnated wooden rod , connected by other rods and bell cranks to a grounded metal handle on the front panel. The whole contact assembly was immersed in a tank of heavy mineral oil which extinguished the arc as the current passed through the AC zero voltage point. AC to DC substations The 6.6kV AC from Ultimo power station allowed longer transmission distances but it then had to be transformed down to a lower AC voltage and converted to DC to supply the trams. For this purpose, five tramway substations were built at Macquarie St (City), Newtown, Waverley, Randwick and North Sydney. Two underground high voltage cables were laid to each substation by the British Insulated Wire Company. These oiled paper insulated cables were lead-sheathed and the lead sheathing was grounded to earth electrodes at both ends and at intervals of about 800 metres along their length. The shortest run was tci the city substation (2.9km) and the longest to North Sydney (6.4km). A 732-metre section to North Sydney was laid on The Ultimo power station had Gothic proportions, with the men in this photo giving some idea of the scale. The massive switchboard is situated at the far end of the building. the floor of Sydney Harbour and is thought to be the first high voltage submarine cable laid in Australia. This underwat er section , from Dawes Point to Blue's point, had extra steel armouring but also contained three submerged joins. This was because the technology of the day in England could not produce cable lengths greater than 185 metres. Arc-gap voltage surge arresters were fitted to .the cables, to flash over if a switching surge or lightning ground The chimney stacks of the Ultimo power station dominated Sydney's skyline for many years but they are now long since demolished. The main building still survives however and now houses the Powerhouse Museum. current elevated the voltage momentarily above 15kV. At each of the five substations , the 6.6kV supply was transformed down by air-blast cooled delta-delta transformers to 375V. This was fed to rotary converters which produced 600V DC to supply all trams in the section. Initially, 450kW and Z00kW converters were installed. But so fast did the system grow that within a few years larger units had to be provided. The largest were the 1.8MW machines installed at the new city substation at Jamieson Street. A rotary converter looks somewhat like a big DC generator with commutator and brush gear but without any mechanical drive. Instead, the AC electrical input is conducted by sliprings and brushes to connections on the back of the armature winding. Readers are probably aware that in any DC machine the armature winding always carries AC , this "being mechanically rectified by the rotating commutator and stationary brushes. This fact is used in rotary converters, the armature rotating at a speed in synchronism with the AC supply. The 600V DC output taken from the comSEPTEMBER 1992 91 This photo shows the interior of North Sydney substation as it was in 1902. It included three rotary converters, each rated at 1200A. In the left foreground are the three switchboard sections controlling the DC side of the converters. At the top are the automatic overcurrent circuit breakers, below that the dynamic ammeters and below them the two open blade knife switches for each machine. mutator by the brushes then fed the tramway system. With the incoming AC at a frequency of 25Hz, the 6-pole rotary converters ran at 500 rpm. Mounted on the back end of the shaft of each converter was a 30kW 4-pole induction motor intended for starting the converter and bringing it up to synchronous speed. Later, these pony motors were dispensed with and the converter started as an induction motor from low voltage taps on the transformer, through limiting inductances. A third method was to start the converter from the substation battery. Dynamic ammeters The large ammeters of the day, with a scale up to 400mm long, demanded strong field magnets. Lacking powerful permanent magnets, manufacturers used 600V DC electromagnets instead. To desensitize the meter against voltage fluctuations, the iron cores were driven hard into magnetic saturation. This was ingenious! Should a machine circuit breaker trip on overcurrent, the operator would stand on a rubber mat and: (a) open the blades of the knife switches; (b) close the circuit breaker; and (c) slam the bare knife switches closed by the handle, at the same time being 92 SILICON CHIP prepared to duck and jump sideways quickly should that closure cause the circuit breaker to trip again. Any circuit breaker opening on over-current could rain down red hot globules of the copper or carbon contacts. Also, the breaking of a high current arc made a thunderclap noise loud enough to scare the living daylights out of the unfortunate operator. 600V batteries Most of the substations were fitted with one or two 600V batteries, each consisting of 280 lead-acid cells. Constructed of lead lined timber and containing nine positive and 10 negative plates, each cell contained 125kg of sulphuric acid electrolyte. Heavily coated timber bearers and glass insulators supported the batteries. Rated at 500 ampere-hours, these batteries could supply up to 1000 amperes for short periods. They were used to supplement the converter output to the trams during peak periods, as well as for far-off-peak supply when the converters could be shut down. Charging and discharging of the 600V battery was controlled by a clever differential booster generator. This machine had its shunt fields separately excited by the 600V bus bar and was driven at a constant speed by a separate DC motor. When there was no tramway load on the substation converters, the booster armature generated 100V. This was added to the 600V bus bar supply to give 700V and charged the battery at 500A. The booster series field was connected in series with the rotary converter, so that series field opposed the booster's shunt field. This meant that when the rotary converters were supplying heavy tramway load, the booster generated less voltage, and so the battery charging current pulled from the rotary converters was correspondingly reduced. During peak hours, heavy tramway loads would occur, often of 3000A to 4000A, such as when 30 trams started simultaneously. Under such a condition, the booster's differential series field would completely overcome its shunt field so that the voltage generated by the booster would reverse. Thus, the charged battery, in parallel with the rotary converter, would share the tramway load. In this way, the load fluctuations on the rotary converters were reduced. Despite the expense of providing substations, rotating conversion machinery and the trained staff to tend them, the new AC/DC system proved economical. The interest paid on loans raised to finance the project was less than the calculated cost of power which would have been lost in feeder voltage drop had the DC transmission system been simply extended. Sydney continued to have an insatiable need for more and more electric traction. Between 1900 and July 1904, electrified track mileage had quadrupled to 192 kilometres, while the number of trams had grown to 500. This rate of expansion continued for years and at the same time Sydney people wanted electric appliances and lights in their homes and streets. Many more power stations had to be built in the years to come. Acknowledgements Grateful thanks for photographs domi,ted by SRA Archives, the Trustees of the Sydney Museum of Applied Arts and Sciences, and the Public Works Department of NSW. Acknowledgements to Don Godden et al in "Ultimo Power House; Report on its History and Technology"; also to Victor Poljanski, Arthur Perry, P. Smythe, P. Tweedie, T. P. Strickland and W. Upton. SC REMOTE CONTROL BY BOB YOUNG Internal combustion motors for R/C models; Pt.2 Last month, we explored some of the basic concepts applied in internal combustion motor design for models of various kinds. This month, we will look at some of the practical applications of these motors and the basic rules for their successful use. Fundamental to the discussion of motors is the understanding and use of some sort of fuel. Model fuels typically fall into two categories: (1) petrol based and (2) methanol based. Petrol based fuels use a mineral oil as the lubricant, while methanol based fuels use a vegetable oil, typically castor oil or a synthetic upper cylinder lubricant. There are exceptions. For example, Castrol M is pure castor oil whereas Castrol R40 is castor oil with modified viscosity due to the addition of a synthetic component. It corresponds to a 40 grade oil. Castrol R30 is a lighter oil of 30 grade. Fuel/oil ratios Very few model motors are fitted These days, most people elect to use an electric starter for their models. Typically, they run from a 12V supply (ie, a car battery) and draw about 6A. with a sump and thus the oil must be mixed into the fuel as with mower or chainsaw fuel. The ratio of the power component (P) in the fuel to the lubricant (L) is quoted as P:L. Thus, a 3:1 fuel has three parts of the power component to 1 part of lubricant. Note that the lubricant takes up volume in the cylinder and this affects the burn characteristics of the fuel, so there is a definite performance benefit to be gained from a reduced oil level. In contest work, this is all important and when combined with other factors, the quest is on for the lowest possible oil ratios. In some MAAA contests, the fuel is supplied so that all contestants are on an equal footing with regards to fuel. All unburnt fuel is ejected from the exhaust system and this includes the lubricant. Thus , the higher the ratio of oil to power components in any fuel, the more residue on the model after the run is completed. Herein lies the problem with castor oil. In the case of an aeroplane, this sometimes thick, smelly and heavy deposit can affect flying characteristics and, in contest work, this is not good. Burnt castor oil has to be one of the most obnoxious substances known to mankind. When using 3:1 fuel, the model lands after a 20-minute flight literallysoaked in a thick black slime. It is difficult to clean off and in time ages into a sticky, gumlike substance that turns glorious paint jobs a dirty grey. It soaks right into models and renders them almost impossible to repair. It also coats everything in a model box - tools , batteries and test equipment - with a mixture of gum and dust. SEPTEMBER 1992 93 A tachometer is invaluable for engine tuning. Commercial models are readily available or you could build the popular unit that was published in the May 1988 issue of SILICON CHIP. Finally, it soaks into the very pores of the modeller himself, rendering him instantly recognisable to other modellers. So there is considerable incentive to reduce the castor oil content in modern fuels, for two reasons: (1) motor performance; and (2) the messy business of castor oil residue. Thus, the stage is set for the argument we will now be examining in some detail. P:L ratio is a very important factor when using model engines and is the subject of endless argument and discussion. There are no hard and fast rules and therefore every modeller has his own pet theory, a situation in which the tyro modeller can be very easily led up the garden path. Engine tuning Central to the argument is the longevity of the model motor. Model engines are very expensive and they can be ruined in one run if the wrong advice followed. Once again, it must be remembered that the lubricant comes into the motor with the power component and at this point a brief explanation of tuning a model engine is in order. The most popular method for start94 SILICON CHIP ing model motors is with an electric starter. This is fitted with a rubber cone which is pressed firmly against the prop spinner. Electrical power is then applied to the starter motor. Thus, to start a glow plug motor, for example, a 1.2 volt battery (usually a 4Ah nicad) is connected to the glow plug located on the top of the cylinder head. The usual method here is a 2-pronged clip which makes contact with the central insulated core of the plug. One end of the platinum glow element is connected internally to this core and the other is connected to the motor body. Current consumption of a typical gl'ow plug is around 4-5 amps although it varies depending upon the heat range of the plug. If it is the first start of a new motor, disconnect the glow plug battery and close the needle valve fully shut by screwing it in the clockwise direction. Now open the needle valve by turning it anticlockwise for two and one half turns. If the needle valve was set correctly last flight, then do not fiddle with it. The motor is then primed by placing a finger over the carburettor air intake and turning the motor over slowly by hand. Watch the fuel inlet tube for signs of the fuel moving through to the carburettor. Once fuel is up to the needle valve, two or three turns are sufficient to prime the motor. Care must be exercised here for several reasons. One is that motors can sometimes start spontaneously, even without the plug connected. It is rare but most experienced modellers have had it happen at least once in their flying careers. Secondly, if the motor is flooded and a hydraulic lock exists, serious damage can be inflicted upon it, especially with small motors. Conrods can be bent or broken very easily with rough handling. For the same reason, when using an electric starter on small motors, use the minimum amount of pressure as the rubber cone then acts as a slipping clutch should the motor hydraulically lock. Once the motor is primed, turn on the R/C set, set the throttle to about one third and connect the glow plug battery. This done, hold the model in one hand, apply the starter cone to the spinner and switch on power to the starter. The motor should spin freely and start within 10 revolutions or so. If it does not start, check that the fuel is flowing through the intake line, that the glow battery is charged and that the plug is glowing. Checking the glow plug In the old days before we used mufflers, one just simply looked inside the exhaust port for that nice rosy red glow inside the cylinder. It was eerie to note that the glow still existed once the motor was running and the glow plug battery had been disconnected. These days, one must remove the glow plug from the motor and connect a battery while viewing the element. The element should glow a healthy cherry red. Once the motor is running, disconnect the glow plug battery, open the throttle to . full and turn the needle valve in the closed (clockwise) direction. As the needle valve is closed, less fuel is delivered to the motor and the revs will gradually increase. Continue th.is process until there is a noticeable drop in rpm; ie, tune for maximum rpm. A phototachometer is a very useful item at this point, giving a clear and accurate indication of the performance changes between different combinations of glow plugs and fuels. Now here is the tricky part and the core of the argument in regard to fuel/ shift in trim as the fuel load is burned off. Running rich This was the first series target aircraft built for the Australian Army by Silvertone Electronics. Called the "Ugly Stick", it was fitted with an OS 40 Schnurle Ported motor. Note that it had plenty of ventilation. If it had been housed inside cowling, ventilation could have been a serious problem. oil ratios. You will remember we established that the oil comes into the motor with the fuel. Therefore, as we tuned the motor more and more in the lean direction, we were delivering less and less oil to the motor and all this at a time when rpm was increasing. If this process is continued on after peak rpm is obtained, then the motor is running with a much reduced oil level and the danger of the motor seizing is very real. This is compounded in flight when the rpm increases due to the prop being unloaded, or the mixture leans out when the nose of the model is raised during a climbing manoeuvre. This is called a "lean run" and if the motor is poorly ventilated, it can easily overheat, thus dramatically increasing wear and tear. In some situations, it can even seize completely. For this reason, once the motor is tuned to peak revs, open the needle about one eighth of a turn in the anticlockwise direction to allow for the increase in revs in flight. Also, hold the nose of the model vertically to ensure that the fuel will continue to be drawn into the motor without the motor leaning out or stopping completely. Fuel tank In the days before nicad batteries, glow plugs were energised with a large 1.5V cell. This particular unit has been fitted with a switch & a meter to check the current. One word here on the mounting of the fuel tank, a vitally important point for a reliable engine run. The tank centreline should be level with the needle valve and as close to the motor as possible. Always use muffler pressure to pressurise the fuel tank, or better still a fuel pump. The latter ensues almost faultless motor runs once set up correctly. There is another benefit with fuel pumps in that the fuel tank may be mounted on the centre of gravity of the model, eliminating the annoying Now the complexity of the argument becomes a little clearer. Typically, a modeller might tell you that he flies with 5% Gloglide (a synthetic oil) and that to add more oil is just a waste. What he probably will not think to mention, for the simple reason that he is probably not really aware ofit, is that by habit, he runs his motors uncowled, slobbering rich, and uses exhaust pressurisation of the fuel tank or a fuel pump; so there is always ample cooling air and ample oil under all circumstances. In other words, from past experience he has found that he does not need more than 5% Gloglide in his models, because of the way he sets them up and operates them. The missing factor is , however, his limited experience, and everybody's experience is limited. New situations are constantly arising and that same modeller may be in for a shock one day when he moves from his old uncowled, fully ventilated motbr installations into a fully cowled scale job fitted with a brand new $400 motor. I have seen many a modeller scratching his head and muttering about the quality of modern motors because his brand new $400 dollar motor welded the piston into the cylinder on its very first run. The key factor So you see the key factor in this argument is the effective level of oil delivered to the motor. One modeller running 5 % oil in a rich mixture is probably delivering as much oil to the motor as a modeller using 10% oil and running at the correct mixture setting. Unfortunately, there is no simple method of establishing what this effective level is. Just be very careful about the advice you accept in this area and as a general rule err on the conservative side until your experience indicates otherwise. My own considerable but still limited experience always dictated 20% castor oil and every time I tried less oil or synthetics, I came unstuck in some way. But then I was always told that I ran my motors too lean (trying to get the maximum rpm) and that I was ultra conservative. SC SEPTEMBER1992 95 Sili,c on Chip netics NE572 Compandor IC Data; Map reader For Trip Calculations ; Electronics For Everyone Resistors. April 1989: Au xiliary Brake Light Flasher; Electron ics For Everyone: What You Need to Know About Capacitors; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. BACK ISSUES July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid To Your Car; Booster For TV & FM Signals ; The Discolight Light Show, Pt.1; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback, Pt.3; Amplifier Headroom - Is It A Con? August 1988: Building A Plasma Display; Universal Power Supply Board ; Remote Chime/Doorbell ; High Performance AC Millivoltmeter, Pt.1 ; Discolight Light Show, Pt.2 ; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone ; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Build The Vader Voice ; Motorola MC34018 Speakerphone IC Data; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Rohm BA1404); High Performance FM Antenna ; Matchbox Crystal Set; Electronic House Number; Converting A CB · Radio To Th e 28MHz Band ; Queensland's Powerful Electric Locomotives. November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man's Plasma Display ; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, Wh at You Need To Know; Diesel Electric Locomotives. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1 ; Diesel Sound Generator ; Car Antenna/Demister Adaptor; SSB Ad aptor For Shortwave Receivers ; Why Diesel Electri cs Ki lled Off Steam ; Index to Volume 1. January 1989: Line Filter For Computers ; Ultrasonic Proximity Detector For Cars; 120W PA Amplifier (With Balanced Inputs) Pt.1 ; How To Service Car Cassette Players; Massive Diesel Electrics In The USA; Marantz LDS0 Loudspeakers. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System ; LED Flasher For Model Railways (uses LM3909); Build A Simple VHF FM Monitor (uses MC3362), Pt.1 ; Lightning & Electronic Appliances; Using Comparators to Detect & Measure. March 1989: LED Message Board , Pt.1; 32-Band Graphic Equaliser, Pt.1 ; Stereo Compressor For CD Players; Amateur VHF FM Monitor, Pt.2 ; Sig - May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom ; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference ; LED Message Board , Pt.3; Electronics For Everyone - All About Electrolytic Capacitors. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586) ; Passive Loop Antenna For AM Radios; Build A Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor); Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers ; Compact Ultrasonic Car Alarm; NSW 86 Class Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC 13024 and TX7376P) Pt.1 ; AlarmTriggered Telephone Dialler; High Or Low Fluid Level Detector; Simple DTMF Encoder; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669). October 1989: Introducing Remote Control ; FM Radio Intercom For Motorbikes (Uses BA1 404 & TDA7000) Pt.1; GaAsFet Preamplifier For Amateur TV; 1Mb Printer Buffer; 2-Chip Portabl e AM Stereo Radio , Pt.2; Installing A Hard Disc In The PC. l. ----------------- ------------------ ---, Use this handy form to order your back issues Please send me a back issue for: O 0 O O O O O O O O October 1988 March 1989 September 1989 February 1990 July 1990 December 1990 May 1991 October 1991 March 1992 August 1992 o O O O O 0 o O 0 November 1988 April 1989 October 1989 March 1990 August 1990 January 1991 June 1991 November 1991 April 1992 0 O 0 O 0 O July 1988 December 1988 May 1989 November 1989 April 1990 September 1990 o February 1991 0 July 1991 0 December 1991 0 May 1992 Enclosed is my cheque/money order for $_ _ _ or please debit my: O O 0 0 0 o O 0 0 O August 1988 January 1989 June 1989 December 1989 May 1990 October 1990 March 1991 August 1991 January 1992 June 1992 0 Ban kcard Card No. Signature _ _ _ _ _ __ __ ____ Card expiry date_ _ /_ _ O Visa Card o September 1988 O February 1989 0 July 1989 O January 1990 o June 1990 O November 1990 0 April 1991 O September 1991 O February 1992 o July 1992 O Master Card $5.00 each (includes p&p). Overseas orders add $1 each for postage. NZ orders are sent air mail. Detach and mail to: Street _ _ __ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 Suburb/town _ __ _ __ _ _ _ _ _ _ _ _ Postcode _ _ __ __ Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503. Name L------------ - -- - --- - - ------- - --- - -- ---- J 96 SILICON CHI P November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); Sensitive FM Wireless Microphone; FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disc Drive Formats & Options ; The Pilbara Iron Ore Railways. December 1989: Digital Voice Board (Records Up To Four Separate Messages); UHF Remote Switch ; Balanced Input & Output Stages; Data For The LM831 Low Voltage Amplifier IC ; Install A Clock Card In Your PC ; Index to Volume 2. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR ; Speeding Up Your PC; Phone Patch For Radio Amateurs ; Active Antenna Kit; Speed Controller For Ceiling Fans ; Designing UHF Transmitter Stages. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries ; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs , Pt.2; PC Program Calculates Great Circle Bearings. March 1990: 6/ 12V Charger For Sealed LeadAcid Batteries; Delay Unit For Automatic Antennas ; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. To One VCR ; A Really Snazzy Egg Timer; LowCost Model Train Controller; Battery Powered Laser Pointer; 1.5V To 9V DC Converter; Introduction To Digital Electronics; Simple 6-Metre Amateur Transmitter. Pt.1; Battery Charger For Solar Panels; Flashing Alarm Light For Cars; Digital Altimeter For Gliders & Ultralights, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; Error Analyser For CD Players Pt.3; Modifying The Windows INI Files. December•1990 : DC-DC Converter For Car Amplifiers; The Big Escape -A Game Of Skill; Wiper Pulser For Rear Windows; Versatile 4-Digit Combina tion Lock; 5W Power Amplifier For The 6Metre Amateur Transmitter; The Great Green CD Pen Controversy; Index To Volume 3. December 1991: TV Transmitter For VCRs With UHF Modulators; Build An lnfrared Light Beam Relay; Compact Solid-State Laser Pointer; Colour TV Pattern Generator, Pt.2; Windows 3 & The Dreaded Unrecoverable Application Error; Index To volume Volume 4. January 1991 : Fast Charger For Nicad Batteries, January 1992: 4-Channel Guitar Mi xer ; Adjustable 0-45V BA Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Automatic Controller For Car Headlights; Experiments For Your Games Card; The GPS Satellite Navigation System; Restoring An AWA Radiolette Receiver. Pt.1 ; The Fruit Machine ; Two-Tone Alarm Module; Laser Power Supply; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens. February 1991 : Synthesised Stereo AM Tuner, Pt.1 ; Three Inverters For Fluorescent Lights ; LowCost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2 ; How To Design Amplifier Output Stages ; Tasmania's Hydroelectric Power System. March 1991 : Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose 1/0 Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV; A Look At The Config.Sys & Ansi .Sys Files. April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Active CW Filter For Weak Signal Reception; How To Find Vintage Radio Receivers From The 1920s. May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors ; The Mozzie CW Transceiver; Waveform Generation Using A PC, Pt.3; 16-Channel Mixing Desk, Pt.4; What To Do When Your Computer Goes Bung , Pt.1. April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24 V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2 ; Playing With The Ansi.Sys File ; FSK Indicator For HF Transmissions. May 1991 : Build A DTMF Decoder; 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1; Setting Screen Colours On Your PC. June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies; A Speed Alarm For Your Car; Design Factors For Model Aircraft; Fitting A Fax Card To A Computer; What To Do When Your Computer Goes Bung, Pt.2. June 1991: A Corner Reflector Antenna For UHF TV; 4-Channel Lighting Desk, Pt.1; 13.5V 25A Power Supply For Transceivers; Active Filter For CW Reception; Electric Vehicle Transmission Options; Tuning In To Satellite TV, Pt.1. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-500kHz); Burglar Alarm Keypad & Com- Ju ly 1991 : Battery Discharge Pacer For Electric bination Lock ; Simple Electronic Die ; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station; What To Do When Your Computer Goes Bung, Pt.3; Weather Fax Frequencies. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2; What To Do When Your Computer Goes Bung, Pt.4. September 1990: Music On Hold For Your Telephone; Remote Control Extender For VCRs; Power Supply For Burglar Alarms; Low-Cost 3Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band. Vehicles; CD Error Analyser, Pt.1 ; Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tun ing In To Satellite TV , Pt.2; PEP Monitor For Transceivers Augu st 1991: Build A Digital Tachometer; Masthead Amplifier For TV & FM ; PC Voice Recorder; Error Analyser For CD Players, Pt.2 ; Tuning In To Satellite TV , Pt.3; Installing Windows On Your PC; Step-By-Step Vintage Radio Repairs . September 1991 : Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders & Ultralights, Pt.1; Build A Fax/Modem For Your Computer; The Basics Of AID & DIA Conversion; Windows 3 Swapfiles , Program Groups & Icons; How Glass-Mount Antennas Work. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; The Bose Lifestyle Music System; Using The NE602 In Home-Brew Converter Circuits. October 1991: Build A Talking Voltmeter For Your PC, Pt.1 ; SteamSound Simulator Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders & Ultralights, Pt.2 ; Getting To Know The Windows PIF Editor. November 1990: How To Connect Two TV Sets November 1991 : Colour TV Pattern Generator, February 1992: Compact Digital Voice Recorder; 50-Watt/Channel Stereo Power Amplifier; 12VDC/ 240VAC 40-Watt Inverter; Adjustable 0-45V BA Power Supply, Pt.2; The Mobile Telephone Revolution; Designing A Speed Controller For Electric Models. March 1992: TV Transmitter For VHF VCRs; Studio Twin Fifty Stereo Amplifier, Pt.1 ; Thermostatic Switch For Car Radiator Fans; Telephone Call Timer; Updating The Resistor/Capacitor Scene ; Coping With Damaged Computer Directories; Valve Substitution In Vintage Radios. April 1992: lnfrared Remote Control For Model Railroads ; Differential Input Buffer For CROs; Studio Twin Fifty Stereo Amplifier, Pt.2; Understanding Computer Memory; Switching Frequencies in Model Speed Controllers; Aligning Vintage Radio Receivers , Pt.1. May 1992: Build A Telephone Intercom ; LowCost Electronic Doorbell; Battery Eliminator For Personal Players; lnfrared Remote Control For Model Railroads , Pt.2; A Look At Large Screen High Resolution Monitors ; OS2 Is Really Here; Aligning Vintage Radio Receivers, Pt.2. June 1992: Multi-Station Headset Intercom, Pt.1; Video Switcher For Camcorders & VCRs; lnfrared Remote Control For Model Railroads, Pt.3; 15Watt 12-240V Inverter; What's New In Oscilloscopes? ; A Look At Hard Disc Drives; Video Editing On The Small Screen. July 1992 : Build A Nicad Battery Discharger; 8Station Automatic Sprinkler Timer; Portable 12V SLA Battery Charger; Off-Hook Timer For Telephones; Multi-Station Headset Intercom, Pt.2; Understanding The World Of CB Radio; Electronics Workbench For Home Or Lab. August 1992: Build An Automatic SLA Battery Charger ; Miniature 1.5V To 9V DC Converter ; The lnterphone Digital Telephone Exchange, Pt.1; Dummy Load Box For Large Audio Amplifiers; Internal Combustion Engines For Model Aircraft ; Troubleshooting Vintage Radio Receivers . PLEASE NOTE: All issues from November 1987 to June 1988 plus the August 1989 issue are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or teaisheets) at $5.00 per article , including postage. When supplying photostat articles or back copies , we automatically supply any relevant Notes & Errata at no extra charge. SEPTEMBER 1992 97 ASK SILICON CHIP Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Line grabber not grabbing I have built a batch of line grabbers (as described in the March 1988 issue) to cope with the modems we have installed in our office. They are being used in conjunction with elec tronic phones and one of the newer Telecom AXE exchanges which puts out about 47V rather than 50V DC. I have found that to make the SCR trigger reliably, I have had to reduce the lO0kQ resistor in series with the 18V zener down to around 89kQ. Can you offer any explanation or comment on this modification? (P. T., Toowoomba, Qld). • We are surprised that such a small change is all that is required. We sug· gest that you reduce the l00kQ resistor to 4 7kQ or 56kQ to make doubly sure that the circuit works. 0 TL075 op amp replacement I have a number of circuits which used the TL075 quad FET-input op amp but, unfortunately, this op amp appears to be no loriger made. Can I substitute a TL074 as the pinouts appear to be the same? (T. R., Rhodes, NSW). • The TL074 does not have the same pinouts as the TL075. In fact, we know ofno direct equivalent for the TL075. The closest we can suggest is the TL085 but its noise performance is not a good and it appears that it, too , is difficult if not impossible to obtain. That leaves the 4136 quad op amp as the only drop-in replacement. However, this is a bipolar device (not FET input). In some circuits, its need for finite bias current (as opposed to the negligible bias current for the TL075) may require slight modifications otherwise there may be problems with DC offsets at the outputs of the op amps. Pan potting single birds Would it be possible to design a project in the magazine which is a stereo mixer with a panpot? I would like to use it to mix a single bird call into a stereo atmospheric recording and to be able to "move" the bird's apparent position. I have seen a pro- Modifying the nicad battery discharger (1) external power source for the op amp and voltage reference. I am very interested in one of your latest projects, the Nicad Battery Discharger, which was published in the July 1992 edition. I have to service Panasonic cordless phones which use a 3.6V 1 lOmAh (3-cell) battery (nicad of course). Can the circuit featured be modified to suit these? (M. C., Brisbane, Qld). • Unfortunately, the circuit cannot be made to work with three nicad cells as the supply voltage to the op amp and voltage reference is too low. It would be necessary to modify the circuit so that it had an Modifying the nicad battery discharger (2) 98 SILICON CHIP Your project on the Nicad Battery Discharger is exactly what I need. Unfortunately, the range of batteries you selected does not cover the units I am using. We need it so: grandchildren using 2-cell battery in electronic games, 2.4V (cut off 2.2V); my daughter as school teacher using portable wireless FM microphone using 3-cells (cut off 3.3V). That's two additional ranges we need. I am using a torch with five cells and fessional piece of equipment but it was of the order of $1000! (S. F., Darling Point, NSW). • While we have not published a circuit which does exactly what you require, you could adapt part of the circuitry of the 16-channel mixer published in the February to May 1990 issues. The issue containing the relevant circuitry is March 1990. Sub-woofers & deep bass notes There are two reasons for writing to you. The first is to comment on the dilemma A.H. (SILICON CHIP, June 1992) is faced with in trying to reproduce the deep bass notes (particularly from pipe organ music) on his stereo system. The second is to add weight to his request for a sub-woofer project. Consider some simple physics. Assuming that sound travels at 335m/s (at sea level and at normal atmospheric temperature and pressure), then unless A.H. 's listening room is 8.4 metres between parallel walls, in the longest dimension, there is no way that 20Hz is going to be faithfully reproduced, as this is the length of a a portable drill with 6 cells but these ranges are already provided. To operate your discharger on 2 and 3-cell batteries, would it be possible to add more tappings for S1 (by cancelling 12 and 9.6V, I may be able to use the same switch) or will I have to change other components; eg the 2.5V reference ZDl which will not work with a two cell battery. (G. R., Burwood, NSW). • As in the previous case, the Nicad Battery Discharger cannot be made to work with two, three or four cells as the supply voltage to the op amp would be insufficient. Once again, it would be necessary to modify the circuit so that ran from an external power supply. half-wave of that frequency. Let's look at this a little further. Given that wavelength (1) = velocity (v)/frequency (f) and that the minimum frequency that can be reproduced in a given room requires that a half-wave be allowed to develop, then a quick use of a tape measure and a calculator will tell A.H. just what the low frequency cut-off of the listening room would be. One commercially available (public address system) sub-woofer loudspeaker enclosure that I know of employs not one but four 15-inch drivers and has a claimed frequency response of 45Hz to lkHz (it handles 500W and has an efficiency of 104dB at 1W at 1 metre). The point that I am making is that A.H. may be chasing that elusive very low octave when it is not available from the loudspeakers alone. However, all is not lost for A.H. Constructional articles which deal with sub-woofer adaptors have appeared in hifi and electronics magazines for many years. Several manufacturers have produced very creditable items which attempt to solve the (lack of) deep bass dilemma - although few make it down to 20Hz. Most use a similar approach. Recognising that deep bass notes are essentially non-directional, a simple resistive mixer (to combine left and right channels) is connected to an active low-pass filter, which in turn is connected to a mono amplifier and finally a purpose-built loudspeaker enclosure. Often, for domestic installations, the design is such that the loudspeaker is small enough to be placed somewhere "out of the way". This simple little project could be connected to a medium-to-high power amplifier to drive the associated loudspeaker. (R. W., Scoresby, Vic). • We do not agree with your analysis regarding room sizes and the lowest frequency which can be reproduced in them. It is true that the longest dimension of a room determines the lowest frequency at which a standing wave can occur but that is not the lowest frequency which can be heard in the room. Consider the case of a piano in a small room. The lowest note on an 88note keyboard is A with a frequency of 27.5Hz or thereabouts. By your analysis, the fundamental and possibly the first harmonic would not be audible but they are. The same situa- Questions on TV antenna designs I would like to ask a few questionp regarding some projects that have appeared in SILICON CHIP over the past few years. For the two TV antenna projects -the 4-Bay Bow-Tie UHF Antenna (January, 1988) and the Corner Reflector UHF Antenna - you built a balun. Is this balun a special ratio balun or could I use a commercial 300/75-ohm unit. What is the impedance at this point? (I thought the impedance would be about 300 ohms). In the 25A 13V Switchmode Power Supply (June 1991), the transformer you specify is a toroidal type. Is there any reason for this except that they are physically smaller. Or is it because an "E" type transformer would "rattle" due to being switched by the control circuit? If space was not a problem and I did not require the full hefty 25A, co11ld I use a high current "E" core type transformer that I already have? No mention of this was made tion applies to car sound systems and clearly you can reproduce very deep bass in cars provided you have the right loudspeaker design. A third example involves the use of sealed headphones. They drive into a cavity which is much too small to set up standing waves over much of the audio spectrum yet good headphones can go down to 30Hz and below. Thank you for your suggestions regarding the sub-woofer filter and power amplifier. However, until we can produce a satisfactory design which is relatively easy to reproduce in kit form, we do not have a solution. Switcher circuit for alternator/inverter To begin, I must thank you for a great magazine. Your articles on electric trains, power generation and other topics like the GPS system are all very well researched and informative. The worst part of it is that I tend to wish that the beginning of each month could arrive a little earlier. in the article. I would like to build this project but the outlay for the toroid would make a series regulated supply the way to go (the heatsinks are in my junkbox). Also, could not the Video Switcher published in June 1992 be replaced with a simple passive switch or two, instead of an active electronic box requiring power and filled with compressed smoke? (P. M., Coffs Harbour, NSW). • You could use a commercial balun for the two UHF TV antennas but the method of termination may present problems and it is likely that signal losses would be higher. As far as the 13V 25A Switchmode Power Supply is concerned, the only reason for using a toroidal transformer is its smaller size. You can use a conventional transformer. Active circuitry is used in the Video Switcher to ensure a good performance. With passive switching, there would problems of picture degradation due to loss of bandwidth and crosstalk between the various video sources. We are in the process of moving to Fraser Island and have to, among other things, provide our own electricity. I have a large bank of 48 x 2V 2 25Ah lead acid cells, an array of solar panels, a 1200W inverter and a 5kVA diesel alternator which I would like to combine as an automatic system. I would like to be able to control the diesel alternator with a time clock to start and stop for 4-5 hours morning and afternoon and use the inverter to drive the lighter loads in between these periods. My first thoughts were to use a simple 240V 50Hz time clock but as the diesel alternator does not generate at exactly 50 cycles, this would not be accurate. Is there some way of building a control system that will operate the diesel starter motor, sense engine starting, monitor the oil and water pressure and temperature, and change from inverter to alternator and back again when the alternator is shut down by a fuel cut-off solenoid? There are various clock-timer ICs SEPTEMBER1992 99 Query on the 5-element FM antenna I recently obtained a copy of the article on the 5-element FM antenna that was published in SILICON CHIP in October 1988. The detail differs from the plan layout in that the dipole span is shown as 1440mm on the plan layout but 1400mm in the detail. No doubt these discrepancies were explained and corrected in a subsequent issue but I am unable to check this, after all this time. In my area, FM radio ranges from 101 .5MHz to 107.9MHz and my worst reception is on 102.1MHz. My questions about the article are: (1). Is the 1440mm only a mistake and should it be 1400mm, and are the other dimensions in the plan layout in proportion to a 1400mm dipole or to a 1440mm dipole? What is best for my area? (2) I notice that the space between the dipole fold is 40mm, while the wires attachment spacing is 52mm. Is this significant? The person who loaned the arti- available. Would it be possible to build on to one of these? (N. M., Urangan, Qld). • We are currently involved in the des ign of a project which is rel evant to your interest but du nut have any circuit that will automatically switch between a diesel generator and an inv erter supply. Compatibility problem with the line grabber On page 92 of the July issue, there was a complaint about compatibility problems between th e Line Grabber (SILICON CHIP, March 1988) and TZ00 telephones . A problem with the earli er TZ00s was th at if a long call on another phone/modem was in pro gress, the reduced line voltage would not enable it to trickle -charge the memory capacitor. Once it reached a certain point (usually 15 minutes into th e call), the starved TZ00 would go low-impedance in a desperate bid to grab some line current. This was probably unnoticed on voice calls but caused all sorts of cor100 SILICON CHIP cle to me phoned your magazine and was told that the 1440mm included the end spacers which had to be cut from the same tube; he accepted that without checking but that doesn 't compute. 1440 - (2 x 55mm) = 1330 not 1400, and it is not accepted drafting practice. (G. S., Tuncurry, NSW). • While you may find the diagram confusing, the figure of 1440mm refers to the effective length of the "folded dipole" when assembled to the dimensions shown. The 1440mm figure includes "end effect" and so is not a simple addition of the end pieces. The diagram is correct. The dimensions given for the dipole bottom pieces are also correct, as is the spacing shown for the attachment of the feedwire. However, you can vary these dimensions by a few millimetres without any significant effect. There is little point in trying to optimise the design for one particular frequency as this will have the effect of reducing the overall performance and the bandwiJth. ruption with data calls. Newer versions (flat keypad and "rubber mat" models) do not give this problem- it's limited to the early "bubbly key" model. (G. S., Ashfield , NSW). Wanted: a telephone call counter I have an adolescent son. To keep some control over outgoing calls., I have a locked telephone. On some occasions , I allow him to use the key to make a phone call. I suspect one phone call becomes 3-4 calls within a short time span. My request: Telecom no longer has an out-going call counter and neither does Tandy Electronics. Can anyone help? (L. C., Berowra, NSW). • We are not sure of the best way to do a call counter. The problem revolves around whether DTMF or pulse dialling is used. Also the circuit needs to tell whether the number dialled was actually answered (ie, determine whether or not the call got through). Perhaps one of our readers has a suitable circuit? Notes & errata Infrared Light Beam Relay; December 1991: on the circuit of Fig.3, the pin numbering for IC1 has been scrambled. Pins 5, 6 & 7 should be swapped for pins 12, 13 & 14 respectively and pins 2 & 3 should also be swapped. Also, the chamfer shown on the pinout diagram of the LT356 should be on the cathode (Kl side. On the wiring diagram of Fig.4, diode DZ is shown the wrong way around. Finally, the parts list specifies a 4 70µF capacitor; this should be lO0µF. Video Switcher; June 1992: three 4 7kQ resistors are missing from the circuit diagram on pages 70-71 , although they are shown on the parts layout diagram. These go between pin 3 of IC5b and ground; between pin 11 of IC6d and ground; and between pin 9 of IC6c and ground. There are also several errors on the parts layout diagram (page 76): (1) the REGl and REGZ designations (bottom left) should be swapped (the pin connections are correct); (2) the unmarked resistor at top centre should be labelled 4.7kQ; (3) the 4.7kQ resistor just below ICl should be 47kQ; and (4) the positive side of the lOµF capacitor below REGZ (after the labels have been swapped) should go to the ground (G) connection of the regulator, not to its input (I) . This will involve cutting the copper track adjacent to the positive terminal of the capacitor and then joining this terminal to the ground (G) connection of the regulator using a short wire link (note: later boards will have this error corrected). Finally, there should be 15 47kQ resistors (not 12) in the parts list, while a 2.ZkQ resistor should also be added to the list. Nicad Discharger; July 1992: diode D3 is shown on the wiring diagram of Fig.Z(a) with reversed polarity. This can lead to a burnt-out 4.7Q resistor in the emitter circuit of Ql and, ultimately, to the destruction of the transistor itself. Portable 12V SLA Battery Charger; July 1992: transistor Q1 is shown reversed on the parts layout diagram (Fig.3) on page 56. Also the polarity of the 220µF capacitor is unmarked. The positive terminal is at the top . 6/12V SLA Battery Charger; August 1992: diode DZ was omitted from the parts list. It is a 1N5404. SC ORDER FORM BACK ISSUES* MONTH MONTH YEAR YEAR MONTH MONTH YEAR YEAR *Back issues are $AS each (incl. postage). Overseas orders add $A 1 per issue for postage. BINDERS Please send me _ _ SILICON CHIP binder(s) at $A14.95 each (incl. postage). Overseas orders please add $A3.00 each for postage. TOTAL PRICE $A SUBSCRIPTIONS 0 New subscription - month to start 0 Renewal - Sub. 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Please have your credit card details ready Fax the coupon with you r cred it card details 24 hours 7 days a week Card expiry date I Mail coupon to : Freepost 25 Silicon Chip Publications PO Box 139, Collaroy Beach 2097 No postage stamp required in Austral ia SEPTEM BER 1992 10 1 .........TCENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. r - - - - - - - - - - - - - - - - - - - - - - - - -, I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I CLASSIFIED ADVERTISING RATES ANTIQUE RADIO Adve rtising rates for th is page: Classified ads: $10.00 for up to 15 words plus 40 cents for each additional wo rd. Display ads (casual rate): $20 per column centimetre (Max. 10cm). Closing date : five weeks prior to month of sale. To run your classified ad, print it clearly on the form below or on a separate sheet of paper & send it with your cheque or credit card details to : Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503 . ANTIQUE RADIO restorations. Your one-stop radio repair shop. Specialising in restoring vintage radios, including chassis rewiring, re-condensing, quality new parts , valves , valve sockets , speakers, power & audio transformers. Second hand radio dials & parts for most brands & models. About 400 radios in stock for sale, restoration & parts. Every restored wireless is covered by a 2year warranty on parts & labour. We restore damaged woodwork & cabinets & French polish (approx. 40 coats). Vintage car radios available for sale or restoration. Repairs done on tape decks. Open Sat. 10am-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613AH. FOR SALE Enclosed is my cheque/money order for $._ _ __ U Bankcard 0 Visa Card or please debit my O Master Card Card No . Signature_ _ _ _ __ ______ Card expiry date___/~._ _ Name _ _ _ __ _ __ _ __ _ __ __ __ _ __ _ _ _ Street _ _ __ _ _ __ _ __ _ _ _ _ _ __ _ _ _ _ __ : Suburb/town _ _ _ _ __ _ _ __ _ _ Postcode_ _ _ __ _ XI I I I I I I I I I L - - - - - - - - - - - - - - - - - - - - -----~ 102 SILICON CHIP WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high resolution, shortwave fax , Morse & RTTY receiving program. Suitable for CGA, EGA, VGA and Hercules cards (state which). Needs SSB HF radio & Radfax decoder. *** "SATFAX" $45 is a NOAA, Meteor & GMS weather satellite picture receiving program. Needs EGA or VGA plus "WEATHER FAX" PC card . *** "MAX ISAT" $75 is similar to SATFAX but needs 2Mb expanded memory (EM S 3.6 or 4.0) and 1024 x 768 SVGA card . All programs are on 5.25-inch or 3.5-inch disks (state which) & include documentation. Add $3 postage. Only from M. Delahunty, 42 Villiers St, New Farm, Old 4005. Phone (07) 358 2785. SOLVE CROSSWORDS/ANAGRAMS· easily: Australian program (IBM) with 60,000+ word dictionary. SASE for more info or $15 + $2.50 p&p for registered copy (specify 720Kb or 1.2Mb). Occam Software, PO Box 93, Moonah, Tas. 7009. MS-DOS PC PRINTER port driven Z80 development system. Includes Fast Z80 Cross Assembler, Z8TBasic and lots of KIT REPAIRS Kits repaired from all magazines . Switchmode power supplies repaired . Design work from start to finish. Computer software consultancy. Ring any time 9am-9pm Mon-Sun EEM ELECTRONICS 10 Bouverie Place, Epping, Vic 3076 Phone(03)4011393 TRANSFORMER REWINDS ALL TYPES OF TRANSFORMER REWINDS TRANSFORMER REWINDS Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 76 1291 . Fax: (065) 76 1003. MEMORY EXPANSION PRICES AT AUGUST 1ST, 1992 SIMM 1Mb x 5 sons 1Mb x 3 sons 1Mb x 8 l00ns 4Mb x 9 B©ns 4Mb x s sons (For SIP add $1.00) $47 $42 $38 $168 $150 ORAM DIP 1 x 1Mb sons 256 x 4 sons 41 256 sons 1Mb x 4 (stat} $24.00 $5.20 $5.40 $2.00 DRIVES SEAG 106Mb 15M SEAG 130Mb 19M SEAG 64Mb 16M SEAG 44Mb 28M $420 $480 $365 $285 IBM PS.2 50/55/70 2Mb 70/35 4Mb $120 $1 80 TOSHIBA T3200SX 2Mb T3100SX 2Mb T5200 2Mb $135 $135 $135 MAC 16Mb FX,Q 2Mb SI & LC 4Mb P'Book $665 $86 $335 BOARDS 8MbATW2MB $236 $234 8Mb PS2 W2MB 4Mb HP Laser W2MB $1 65 8Mb PANAS W2MB $180 1Mb TI WlMB $85 Sales tax 20%. Overnight delivery. Credit cards welcome. Ring for Latest Prices Plans Kits and PCBs 10OW Valve Amp PCB ............................................. $30 Valve Amp PSU PCB .. ................. ..... ..... .. ........... $25 Universal PSU (±5/±12V} Dual Supply .................. $10 Digi 125 l0OWamp/pair ........................... .. ............. $10 ETI 1623 PIA for PCs ........................... $40 Max 110 Board .. ..... $40 Max Kit... .... ............ $169 LM380 3.5 amp PCB ..................... ........................... $7 AEM 35W amp kit ... . ................................ $20 ETI Audio Toolkit PCB .................... ... ... .............. $10 AGC Amp PCB ........ ............................................. $7 Z-80 Miniprocessor PCB .................... ........ .......... $50 6502 Miniprocessor PCB ............. .. .. ....................... $50 6809 Miniprocessor PCB ... ...... ................... ............ $50 8048/8049 Developers board complete B&T .......... $199 IBM PC Prototype PCB... ............... $50 EPROM Programmer ........ . .......... ............... .. $299 ESL-1 Electrostatic speaker kiVpair inc manual ...... $899 ESL-1 Assembly Manual ....................................... $50 P.C. Computers (08) 332 6513 36 Regent St, Kensington SA. PELHAM Tel: (02) 980 6988 Fax: (02) 980 6991 1st Floor, 100 Yarrara Rd, PO Box 382, Pennant Hills, NSW 2120. FIX-A-KIT KIT REPAIR & CONSTRUCTION source code. Once only initial outlay for the short form kit $76. Additional CPU blank boards $35. For .more information, send a 45c stamp to Don McKenzie , 29 Ellesmere Crescent, Tullamarine 3043. Phone (03) 338 6286. KIT REPAIRS: fixed price servicing for all kits , no job too small , only quality components used. Ph (02) 649 2134 after 5pm . SECURITY ALARM COMPONENTS: commercial quality alarm panels, detectors, cable , everything for complete alarm system. DIY kits. Discounted prices. 4-core alarm cable $35 per 100m. 2-core alarm cable (figure-8) $15 per 100m. PIR detectors pulse count $59 ea. Horn speakers $12.50 ea. Mail order service send SAE for free price list to Security Distributors, 141 Todds Rd, Lawnton , Old 4501 . Phone (07) 882 0002. GEL BATTERIES: famous Gates brand dual-cell batteries enclosed in a plastic moulding, 4V 5Ah, brand new, fresh stock, fully charged , limited supply at $18 ea or 3 for $45. * UV PENS: the writing of these pens is only visible under UV "Black Light". $2 ea or 5 for $8. * LIGHT MOTION DETECTOR : small PCB assembly based on a ULN2232 IC . This device has an inbuilt light detector, filters, timer, narrow angle lens, and even a siren driver circuit that can drive an external speaker. Will detect light level changes of ±5% at distances of up to 3 metres. Can be used at ve ty low light levels and even in total darkness. With IR LED. Full information provided. The IC only is worth $16! Our price for the assembly is $6 or 5 for $25. * METAL CASSETTES: you can hear the difference with these premium quality 90-minute pure metal cassettes. These were recorded on once, never played, and then bulk erased. The record tabs have been removed. $6 ea or 10 for $50. * BARGAIN MONOCULAR VIEWER: a very small but complete IR telescope which only needs an EHT power supply, which is provided in kit form . PCB and all on -board components only. Limited stock. $229 for the IR telescope and the EHT supply kit. * SWITCHED MODE POWER SUPPLIES: compact enclosed exTelecom supplies. Dimensions: 300 x 90 x 180mm. Unregulated input: 3050V, regulated output of 12V <at> 6A or · 12v<at> 8A or 5V<at> 40A. Three different units. Limited stocks<at> $28 ea. P+P $7 (heavy!). Specify type when ordering (item No.0145) . * MUSIC ON HOLD PCB: small PCB assembly based on a 7910 CF music generator IC. Apply 312V across two connector pins to ob- 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE HVCAL ELECTRONICS Design. Manufacture & Repair of Electronic Equipment (02) 633 5477 tain music from one of the IC pins. Basic information and a circuit diagram is provided . $4 ea (item No .0146). * MICROSWITCH COLLECTION: a mixture of no less than 10 small and large, new, mil-spec microswitches . $6 for the col lection (item No.0148). * MAINS RATED RELAYS: four separate SPST switches (24A) actuated by a mains rated solenoid. $10 ea (item No.0128) . We also have some SPOT mains relays which will switch up to 10AAC. These are fully enclosed in an attractive clear plastic housing. $12 ea (item No.0149). * LARGE ROTARY SWITCHES: these large rotary switches have "snap in" action and all are rated at mains voltages or higher. They have at least three positions and have currents ratings from 10-35A. Great for high power mains and antenna switch- WANTED: YOUR CIRCUIT & DESIGN IDEAS Do you have a good idea languishing in the ol' brain cells. If so, why not sketch it out, write a brief description of its operation & send it to us. Provided your idea is workable & original, we'll publish it in Circuit Notebook & you'll make some money. We'll pay up to $60 for a really good circuit but don't make them too big please. So transfer your idea to paper & send it to Silicon Chip Publications, PO Box 139, Collaroy Beach, NSW 2097. SEPTEMBER1992 103 i SILICON CHIP BINDERS r I I These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers and are made from a distinctive 2tone green vinyl that will look great_ on your bookshelf. I I I * High quality. * Hold up to 14 issues * 80mm internal width. * SILICON CHIP logo printed in gold- Advertising Index Adilam Electronics ........ ... ... ....... 27 Altronics ................................ 80-82 All Electronic Components ... ... .... 5 Antique Radio Restorations ..... 102 A-One Electronics .... .... .... .... 44-45 Av-Comm ................................... 31 Comma Corporation .. ................ 26 Data Electronics ........................ 26 David Reid Electronics .......... ... ... 3 Dick Smith Electronics ...... .. .. 50-55 EEM Electronics ...................... 103 coloured lettering on spine & cover. Economic Electronics ................ 38 Electronic World ........................ 85 Yes! Please send me _ _ __ SILICON CHIP binder(s) at $A11.95 plus Emona Instruments ................... 75 $A3 p&p each (NZ $A6 p&p) . Geoff Wood Electronics ... .......... 77 Enclosed is my cheque/money order for $_ _ _ _ or please debit my Harbuch Electronics .... .............. 67 o Bankcard Hewlett Packard ........................ 21 O Visa Card O Master Card Hycal Instruments .................... 103 Card No. ~~I '---I~ ~ l '---1~~I IL___ L_____!____L _ _ J Jaycar Electronics ..... 33-36,69-72 JV Tuners .................................. 67 KT Technology ......................... IBC Signature_ _ _ _ _ __ _ _ __ _ Card expiry date_ _ _/_ __ National Instruments ............. OBC Name _ __ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ __ Oatley Electronics .............. 22,103 Obiat Pty Ltd ........ .... ....... .... ..... IFC Street _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ PC Computers .. ....................... 103 PC Marketplace .......... ....... ...... .. 25 Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode._ _ _ _ __ SILICON CHIP PUBLICATIONS PO Box 139, Collaroy Beach, NSW 2097, Australia. Phone (02) 979 5644 Fax: (02) 979 6503. L------------- ___________ J ing. Only $15 ea (item No.0151 ). * LARGE FANS: powerful ball bearing mains powered fans: 220V/0.13A, 173mm diameter by 60mm deep. Thermally protected, finger guard included, removed from new equipment. $9.90 (item No.0152). * TEMPERATURE CONTROLLERS: mechanical temperature switches, designed for switching air conditioning (heating/cooling) systems directly. Adjustable temperature controls and mains-rated switches, can control currents of at least 8A directly. Most are rated for typical ambient temperature ranges but some higher temperature types are also available. All come with specifications. $35 ea (item No.0152). Major cards accepted with phone and fax orders. Certified p&p Australia $5, NZ (airmail) $10. Oatley 104 SILICON CHIP Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. Fax: (02) 570 7910. Pelham .................................... 103 Peter C. Lacey Services ............ 64 Philips Test & Measurement ...... 19 Procon Technology ......... ........... 25 RCS Radio .............................. 104 Reserve Electronics .................. 75 Resurrection Radio .......... ...... .... 43 Rod Irving Electronics .......... 10-15 Silicon Chip Binders ........... 87,104 Transformer Rewinds .............. 103 Wombat Communications ......... 76 RCS RADIO PTY LTD ~i~1,~ I ll 16if~I Ill ;=I 0 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. RCS Radio Pty Ltd is the only company that manufactures and sells every PC board and front panel published in SILICON CHIP, ETI and EA. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. RCS Radio Pty Ltd, 651 Forest Rd, Bexley 2207. Phone (02) 587 3491 • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. Starring KT OAT KT 386SX-20 KT 386-25 KT 386-33 KT 486-33 KT 386 NOTEBO.OK * * * * • New Costumes • All Australian Support Cast Our Promoter is seeking Dealers wishing to present this talented new range of PC Performers to the Australian Public. Don't miss your opportunity to book your place in this ever expanding dealer network. ,. KT TECHNOLOGY ~~~~!~~ iu~1~~r:~ ~ ~~~~evard, Port Melbourne 3207 Tel: (03) 646 5755 Fax: (03) 646 7997