January 1991 - Silicon Chip Online

Outer Front Cover
Contents
Publisher's Letter: Electric vehicles: the way of the future?
Feature: Take Care Servicing Microwave Ovens by Jim Lawler
Feature: Electric Vehicles: The State Of The Art by Gerry Nolan
Project: Have Fun With The Fruit Machine by Bruce Baguley
Project: Fast Charger For Nicad Batteries; Pt.1 by John Clarke & Greg Swain
Vintage Radio: My fancy European models by John Hill
Project: Build A Two-Tone Alarm Module by Darren Yates
Order Form
Feature: Amateur Radio by Garry Cratt, VK2YBX
Serviceman's Log: All the makings of a Chinese puzzle by The TV Serviceman
Project: Build A Bigger Laser by Otto Priboj
Feature: Computer Bits by Jennifer Bonnitcha
Project: LCD Readout For The Digital Capacitance Meter by Barry Naujok
Back Issues
Feature: The Story Of Electrical Energy; Pt.7 by Bryan Maher
Market Centre
Advertising Index
Outer Back Cover

This is only a preview of the January 1991 issue of Silicon Chip.

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AUSTRALIA'S DYNAMIC ELECTRONICS MAGAZINE~ ~icrowave Ovens: The Risk To The Serviceman T/4e? calf be ~t/4alt<1/4el( t/4ilf/6'/tl t<1r-t19 Have Fun With The Fruit Machine ~am!~ bat rlolf t loo'e ftlC<r- 6'/41ie-t n's Log - How Q Supply For Laser ~abrtz Crystals : What To Do If o·isaster u Strikes es - Hard WELLER SELF-IGNITING CORDLESS PYROPEN * f-v\53:l..DERllP A...US f-OT B.D/1/llP ::~=~FU $139.95 *D.C.VOLTAGEUPT01CXXJVdls *AC. VOLTAGEUPTO~Vdls *D.C. AMPHERE UPTO 1(}\rrp *DkJOETEST *RESISTANCEUPTOa,,110 il'JClJJDESTESTLEADS&t-.WlJAL * SOLDERING TEMP-250"\o 500"C, f-OT BLOW fSJ'C ONLV$39.95 BONUS FREE CAN OF WELLER GAS !! 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NOWIN STOCK Protects Vehicle from: CITIZEN SR-30 SCIENTIFIC CALCULATOR FEAlllffi ei- ~ [ -· •· ,,_,_ i ~ -···--... 2-:.: ... _ 1 1~- --~·:·-·- ·- r-£?'~"7J.~ ~-==: ... • Display: 8 dig! iqud aystal wnh 3 sign symbols • Capacity: 8-dgit mantissawnh sign, and 2-dgt exporentwnh sign. • 01e mepen::lent an.rmJairg merroy. • Scientific notation wnh a wide range of 200 decooe (·99 lo 99) • ~ one l<ey cperate brlrig:ro-refu • Mixed chain calculation . • AlgebraK,operalion for arilhma!icfurdions. • Scientificfurctions: sin, oos, tan, sin"',oos', ta,', klg, 10', n, e', y', '(1/, b, x', [ ], EXP, 1/x. • The mh.ts sign of the malis.sa s lba1rg mnus. • Auloma!iopo,.,ertum off· about7-8 minutes. • S1atislical furdions: X, on', (on) 2, DATA, ONLV $129.00 ,, COMPUTER DISKETTES Two charging Rates: * Quick charge · 4 Hours * Normal Charge · 15 Hours Includes 2 x 'AA' nicad's FREE !!! ARLEC - 9 VOLT NICAD BATTERY ONLY $18.95ea GOING OVERSEAS ??? Travel Adaptors are just what you need! 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FEATURES 6 Take Care Servicing Microwave Ovens by Jim Lawler They can be lethal when things go wrong 14 Electric Vehicles: The State Of The Art by Gerry Nolan New developments promise a brighter future 98 The Story Of Electrical Energy, Pt.6 by Bryan Maher Tasmania's hydroelectric power system PROJECTS TO BUILD 22 Have Fun With The Fruit Machine by Bruce Huguley Just like the real 'pokies' but you don't lose your shirt 32 Fast Charger For Nicad Batteries by John Clarke & Greg Swain FANCY A CRACK AT the pokies but don't fancy losing your shirt? This project will satisfy your gambling passions. See page 22 Runs from a 12V car battery, charges nicad packs up to 30V 48 Build A Two-Tone Alarm Module by Darren Yates Perfect for games, doorbells or as an alarm indicator 80 Build A Bigger Laser by Otto Primoj New power supply can drive tubes ofup to lOmW rating 92 LCD Readout For The Capacitance Meter by Barry Naujok Uses 4½-digit LCD panel & is battery powered SPECIAL COLUMNS 42 Vintage Radio by John Hill My fancy European models 66 Amateur Radio by Garry Cratt How quartz crystals work 72 Serviceman's Log by the TV Serviceman All the makings of a Chinese puzzle 88 Computer Bits by Jennifer Bonnitcha Hard disc failure: what to do when disaster strikes THEY MAY BE CONVENIENT to use but microwave ovens can be lethal for the unwary serviceman. Our article on page 6 highlights the dangers. DEPARTMENTS 3 Publisher's Letter 4 Mailbag 52 Subscription Page 61 Product Showcase 86 Circuit Notebook 94 Back Issues 2 SILICON CHIP 96 Bookshelf Ask SIiicon Chip Notes & Errata Market Centre Advertising Index 107 109 110 112 NEW TECHNOLOGY has considerably brightened the prospects for electric vehicles. This month, we begin a new series that looks at the state of the art. Turn to page 14. PUBLISHER'S LETTER Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Advertising Manager Paul Buchtmann (02) 979 5644 Mobile: (018) 28 5532 Victorian Representative Hugh Anderson Pty Ltd (formerly McDonald Woodside & Associates Pty Ltd), 119 Market St, South Melbourne, Vic 3205. Phone (03) 696 5411. Contact: Ian McDonald. Electric vehicles: the way of the future? We haven't heard much about electric vehicles in the last few years have we? You'd be forgiven for thinking that the topic was dead and that new developments were few and far between but that is not really the case. In fact, the cars running in the annual Solar Challenge are electric vehicles with the addition of solar panels on the roof. The average speeds being achieved by these vehicles are surprisingly high - something that augurs well for the future. Over the next few issues of SILICON CHIP we are going to have a fresh look at the subject of electric vehicles, with the first article appearing this month. If the price of fuel continues to rise over the next few years, there will be increasing interest in electric cars. Ultimately, electric cars could replace most conventional cars, especially if they are helped along by government legislation. This could well happen if governments make concerted moves to reduce the nation's carbon dioxide emissions. Some of the technology which will be used in future electric cars will possibly come from the exotic motors presently being used in radio controlled electric model aircraft. We just touched on this subject in Bob Young's Remote Control column in the November 1990 issue. And some of the technology could also be a development of that now being used in modern electric locomotives with 3-phase motors and solid state control, as described in some of the later episodes of The Evolution of Electric Railways. Whatever the technology used and whatever form electric vehicles finally take, we think they will be a welcome innovation on Australia's roads. They won't produce lots of pollution when they're stuck in traffic and with the combined effect of regenerative braking and solar cell battery charging, their energy requirements should be much lower than existing conventional vehicles. "What about air-conditioning?", I hear some of you ask. Well maybe, we'll have that too. In the meantime, read the article on electric vehicles in this issue. Leo Simpson Regular Contributors Brendan Akhu.rst Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Glen Cameron 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. All material copyright©. No part of this publication may be reproduced without prior written consent of the publisher. Printing: Magazine Printers Pty Ltd, Rozelle, NSW 2039; Macquarie Print, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, refer to 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 39, 5 Ponderosa Pde, Warriewood, NSW 2102. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 JANUARY 1991 3 SILICON CHIP, MAILBAG Evolution of electric railways was good I really enjoyed Bryan Maher's series "The Evolution of Electric Railways" which SILICON CHIP carried from November 1987 until March 1990. As a professional writer myself, I appreciate and admire the immense amount of work Bryan must have put into researching, obtaining and collating material, and finally producing these in-depth articles. I hope the sudden "winding up" of the series wasn't a result of a few negative comments in the Letters columns! I have just completed my third reading of the series, largely as a result of a recent visit to Queensland and NSW and having seen in action the electrification systems Bryan wrote of in several articles, and also two trips on the New Zealand North Island 25kV electrification system which uses 3000kW locos. I was left with the following questions which I would be grateful if SILICON CHIP or Bryan Maher could answer. (1) What was the topic of Part 3, published in January 1988? Like most other people who couldn't get SILICON CHIP reliably at the start, I missed this issue as a back copy! In NZ, many publishers of periodicals send copies of each issue to libraries (eg, the NZ National Library) to be held for future research. Does SILICON CHIP do this and if so to which libraries? (2) Part 11 (Sept. 1988) shows a photo of "the lightweight catenary" ... etc. "Note the negative (my italics) return wires on the mast". Now I thought this was an AC system! Similar wires, but called protection wires and on much larger insulators, have also puzzled me on the New Zealand North Island 25kV electrification. What is the purpose of these wires, since the rails supply the return for the 25kV AC? The full need for the extensive bonding rather than just grounding of all the structures, insulators etc (even fences!) would be of interest. (I appreciate the safety aspects of 25kV AC!) (3) Part 12 (October 1988, page 78) references the distribution system in 4 SILICON CHIP relation to the state grid and the use of "centre tapped trackside transformers". Any chance of a diagram or more explanation on this? (4) Part 12 references Locotrol, "which we will investigate in a later episode of this series", but regrettably we never did. Any chance of a supplement on this? (5) Part 21 discusses the NSW 86 Class Electrics (July 1989), but the caption under the photo at the top of page 86 is a puzzler. "The loco weighs 120 tonnes with a full load of fuel (my italics) and ballast. What does that mean? (I thought an electric loco's fuel was located some distance away at the generating station!) (6) While I was in Queensland I saw and photographed some electrics with 3900 road numbers, which appear superficially similar to the 3500 class, which Bryan discussed along with the 3100 class in part 12. Can he or any reader provide more information on the 3900 series? (7) I wrote to Bryan Maher about April 1989 suggesting he consider an article on the New Zealand North Island 25kV electrification which, although perhaps similar to the Queensland system, would have been especially interesting to "us Kiwis"! I have found it difficult to find technical articles on the project here and if Bryan or anyone else has information, I would be grateful for references to articles or even copies of articles, if necessary on a loan basis. In summary, I think the "evolution" series was fascinating, and not at all out of place in an electronics magazine. The new series on power generation promises to be as interesting and informative. K. MacDonald, Silverstream, NZ. PS: Not related to any of the above was an index ever published for SILICON CHIP Volume 1 (2 issues in 1987 and the 12 issues of 1988)? If it was , I haven't found it! Comment: We'll answer your questions in order. (1) The topic of the January 1988 issue was largely on the subject of braking, with vacuum PO Box 139, Collaroy Beach 2097. brakes and the Westinghouse system being covered. SIUCON CHIP complies with the "Legal Deposit" provisions of the Copyright Act 1968 and therefore sends copies of every issue to specified State and Parliamentary Libraries in each state plus the National Library of Australia. The index for Volume 1 was published in the December 1988 issue on pages 94 and 95. (2) & (3) The explanation of the autotransformer system for the 25kV catenary would take up quite an amount of space. Bryan Maher plans to cover it in a future chapter in the The Story of Electrical Energy. (4) We did intend to do a story on the Locotrol system but Bryan Maher was not able to get sufficient material from overseas sources. If we eventually obtain sufficient material or one of our readers can provide it, we will run the story in the future. (5) We were embarrassed about the reference to fuel in the photo caption for the 86 class but we have concluded that the fuel may have been meat pies for the crew. (6) & (7) We don't have any further information on the Queensland 3900 class or the NZ electrification. AM stereo radio works extremely well I am quite intrigued by the stereo reception problems experienced with the AM Stereo Radio, as outlined by your correspondent, B. W., Bulleen, Vic, just 13km from Melbourne city (SILICON CHIP, November 1990, page 116). While writing this letter, I am listening to stereo music (albeit with some noise) from a Melbourne commercial radio station, at night, from my home in the Blue Mountains, NSW, on that same receiver which I built some several months ago. Indeed, when correctly aligned, virtually every channel on the broadcast band is occupied during the hours of darkness , with stereo stations available by the dozen! Furthermore, because of the excellent AGC characteristic, fading is far less obvious than any portable receiver I have encountered. Local daytime listening shows that ZWS (Blacktown) and the Sydney ABC stations, all about 35km distant (direct line), are almost noise free. The remaining Sydney commercial transmitters, some 45km distant, do have a degree of audible hiss, with ZCH and ZSM at the worst end of the spectrum. Like B.W., I too use the receiver each day during my 70km rail journey into Sydney. It sits happily on the window-ledge and does not drop out of stereo unless bumped. The one snag is the trains' electric motors which generate a ringing tone at perhaps 200Hz (plus others), so judicious choice of seating is necessary. I should mention here that because of my circumstances and following listening tests in all three modes, I chose the mid-selectivity mode when completing the receiver. I would have opted to incorporate a switchable selectivity facility - but backed away from the idea on advice that performance would suffer. A further refinement would be a stereo/mono switch because under noisy conditions there is subjectively less interference in mono. I am using Koss KSPZ headphones and concur with B.W.'s comment concerning those supplied with the DSE kit. I also substituted a plastic ·front panel - as opposed to the aluminium one that was provided. While I also experience a mismatch in volume at the low end of the pot, I have not bothered remedying this aspect. The one hassle which beat me during construction was soldering the 3mm LED. Not owning the ultra-miniature iron needed to fit inside the tiny gap was the cause. Even using low temperature on my iron, several LEDs were destroyed and finally the track broke away from the PCB. I simply omitted the LED from my receiver. Should a modified unit be described in future, I would dearly love to see a larger ferrite rod to reduce noise level for we "out of city" listeners, a system of switching the three selectivity options and a stereo/mono selector. FM/ AM comparisons notwith- standing, those who have listened to this radio have been immediately struck with its fidelity and have remarked: "AM radios just don't sound like this!" D. Hobbis, Winrnalee, NSW. Comment: Your Jetter is of considerable interest and confirms that this receiver can give a very fine performance. Next month, we hope to present the first in a series of articles describing a fully synthesised AM stereo tuner, for use with hifi systems. We think it will be very popular. Selling software is not easy For the last 2 months I have madly been teaching myself BASIC, first with Microsoft Quick Basic Version 4.5, then later on with Quick Basic Version 7;0. The reason for this mad rush of input is so I can develop customised software for those who need something different and also to earn a living at something that I find to be totally rewarding. So far I have written an insurance program that covers policy holders (both individual & company), and agents' commissions based on different things such as month, year, etc. My reason for writing is to find out whether there are others around Australia and New Zealand who are doing a similar thing to myself and whether they have had any luck in marketing their programs. If so, I would like to know how they are going about it. I look at home-grown software development as being on a par with Australian inventors. I went to an Inventors' Association meeting some 6-7 years ago and the most despondent thing that came of it was that all these inventors had to go overseas to market their design, as Australian manufacturers were just not interested in home-grown development. Australia is full of exceptionally bright people who don't win a Young Achievers' Award every year but who have the capacity to design software which might only sit on their hard disc if they don't have an avenue to sell it here in Australia. After all, greats such as Microsoft, Xtree and others had to start somewhere! If you are one of those people, I would like to hear from you, and maybe we may be able to do something as a group, rather than as a lone programmer hunched over his PC, putting the finishing touches to a brilliant program that no-one but he will have the privilege of using. T. Jones, 18 Boyd St, Ingham, Qld. Why the unbalanced line input on the 16-channel mixer? May I raise a question regarding the SILICON CHIP 16-channel mixer. Why have a "line unbalanced input" switch position? I am not suggesting that there is any point now in changing the design and labelling but I do think a 2-pole 2-position mic/line switch would have covered all requirements. I would be most interested to be convinced otherwise by yourself or other readers. My points are these: (a) I would expect the balanced line input of the mixer to accept the signal from a source with unbalanced output, with no necessity to ground the "cold" side of the input pair in the mixer; (b) By switching the mixer to "line unbalanced", it is also possible that one could be creating an earth loop problem if there is already a conduction path between the "grounds" of each device; (c) There appears to be universal agreement that pin 1 of Cannon type connectors is for shield. However, just to make life inconvenient there is not universal agreement as to which of the other two pins is "hot" and "cold". Try using a normal Cannon connector cable from the output of a piece of equipment which has pin 3 grounded to the mixer input with pin 2 grounded! Thank you for an excellent magazine. F. G. White, Epping, NSW. Comment: we expect that the signal to noise ratio of the mixer preamplifier would be slightly better when one input is grounded but we agree that the circuit would function without the line unbalanced condition. Would any readers like to comment on the question of Cannon connectors? JANUARY 1991 5 Take care servicing • m.1crowave ovens all, the old TVs used valves in the high voltage section, and a magnetron is just another kind of valve. Without some knowledge of circuit theory, one may not realise that the high impedance of the 17kV circuit would limit the current to a relatively safe level. · On the other hand, the microwave's high voltage is supplied via a low impedance transformer, with only a hundred ohms or so of resistance in the secondary winding to limit whatever current might flow when the cirBy JIM LAWLER cuit was completed. In normal operation, the naturally high impedance of On 15th November 1989, a service- the Coroner's suggestions for correct the magnetron is all that prevents catastrophic currents from wrecking man was killed while repairing a tools and clothing are followed. One clue to the origin of the prac- the oven. microwave oven. To give the full deMake no mistake! The high voltage tails, we reproduce a report by the tice came from the Service Manager Victorian Deputy State Coroner into of a company well known in the mi- circuit in a microwave oven is lethal! the death. We suggest that you read crowave field. He suggested that the The power transformer delivers habit of sparking the ultor cap of an around 4000 volts AC, at anything up the report before continuing. It's not an easy matter to comment old black and white TV to check for to half an amp. And the high voltage on this tragic accident, yet comment high voltage has been carried over capacitor ensures that every joule of into the new technology by some that energy is available, ready to kill needs to be made. Accidents don't just happen. They people who lack proper knowledge the unwary serviceman. There is no of the circuits they are handling. hope of surviving contact with that are caused by someone or something. It might be thought that if it was sort of energy and no properly trained And somewhere there has to be a safe to spark the 17kV in a TV set, it serviceman would ever knowingly cause for this one. In preparing this article, I have must also be safe to do the same with put himself at risk by working on a asked a number of microwave manu- only 4kV in a microwave oven. After live microwave oven. So be warned. No matter facturers if they had ever rehow blase anyone may be commended the procedure folabout working on mains powlowed by the deceased at the time of his death. None of them ered appliances such as TV sets, washing machines and has done so. dishwashers, microwave ovI have also spoken to many technicians about their servicens are an entirely different matter. They are extremely ing methods and none of them dangerous. have ever used the method Editor's notE:1: we do not described in the Coroner's reagree with the coroner's recport, although one had heard that there were those who used ommendations for working on the method. In fact, no-one to live microwave ovens, in the whom I spoke would ever conuse of insulated clothing or sider working on a live oven in tools. Microwave ovens are any way, shape or form. just too dangerous for that. In So it puzzles me where the our opinion, they should not practice arose. It seems to be a The large power transformer inside a microwave oven be worked at all on while they risk-filled procedure, even if generates around 4000V AC & is potentially lethal. are live. While everyone appreciates the convenience and speed of microwave ovens, they can be very dangerous in the wrong circumstances, as can any electric or electronic appliance. We feature this report as a timely reminder that doing any service work on a microwave oven, while it is connected to the mains power, is extremely dangerous. 6 SILICON CHIP The Coroner's Report Case No. 4851/89 14th May, 1990 RECORD OF INVESTIGATION INTO DEATH I, GRAEME DOUGLAS JOHNSTONE, Deputy State Coroner HAVING INVESTIGATED the death of JEFFREY ALLAN DOHERTY with inquest held at the Coronial Services Centre, South Melbourne on the 7th May, 1990 FIND that the identity of the deceased was JEFFREY ALLAN DOHERTY and that death occurred on the 15th November, 1989 at 5 Harwell Street, Ferntree Gully from electrocution in the following circumstances. (1 ). At approximately 4.30 pm on the 15th November the deceased a self employed Electrical Appliance Serviceman was called to 5 Harwell Street to repair a faulty Toshiba Microwave Oven . The deceased was repairing the oven using faulty pliers when he received a high voltage electric shock. (2). The deceased had disconnected the cables from the high voltage transformer at the terminals of the magnetron unit and touched the lug on the end of the cable against the magnetron terminal whilst waiting for a spark. He had undertaken this procedure on many occasions previously. He was holding the lug with a pair of Insulated Sidchrome Combination Pliers. The pliers had a crack and small hole in the insulation to the handle which resulted in an insulation breakdown. The crack resulted in the insulation being ineffective with the high voltage. The deceased was wearing jeans, a short sleeved shirt and leather boots. No insulating gloves were being worn. (3). The deceased was the director of J. A. Appliances Pty Ltd and that company was engaged in the repair and servicing of washing machines, dishwashers and microwave ovens. The deceased had attended various courses on the repair of microwave ovens being run by Toshiba and National. It appears that his general training was by practical experience in the appliance repair industry. AND I FURTHER FIND that the deceased contributed to his own death by repairing the microwave oven using faulty pliers with the power on and thereby receiving a high voltage electric shock. RECOMMENDATIONS AND COMMENTS I propose to forward my Findings, Recommendations and Comments to the Attorney-General for dissemination to the Minister Department of Labour, the Chairman of the State Electricity Commission , the Electrical Development Association, the Electrical Contractors Association, the Electrical Contractors Federation (Victoria), the Electrical Wholesale Association (Victoria), the Electronic Technicians Institute, the Victorian Employers Federation, the Trades Hall Council and Toshiba (Australia) Pty Ltd. It is essential that the facts of this case be widely distributed by the State Electricity Commission to all appliance manufacturers and distributors (especially of microwave ovens and television sets), all licensed electrical mechanics and contractors, and all persons working within the appliance service/repair industry. (An obvious source of dissemination of the information would be the yellow pages). There is no requirement for electrical appliance repair or service personnel dealing with plug-in appliances such as televisions, washing machines, dish washers, microwaves and the like to have any form of State Electricity Commission License. It is noted that restricted licenses are required where personnel are working on appliances that are permanently connected to supply. It would appear that electrical appliance repair/service personnel learn their trade through personal experience and interest or occasional training in the event that they work with a large appliance repair company. · There is an obvious need as highlighted by this case for both formal training requirements followed by restricted licenses for all electrical appliance repair/service personnel. It is understood that this matter is currently being examined by the State Electricity Commission. This case also highlights the dangers associated with the failure to ensure that appropriate equipment is used in all electrical work (especially with high voltages) in that: (1 ). It is imperative that the insulation on pliers, screw.drivers and the like be regularly checked. In the event that work is being conducted with high voltage appliances the appropriate type of pliers should be used. (2). Insulated gloves should always be used when working with high voltage appliances. (3) . Clothing should be appropriate for the job at hand in that the following items should be worn : (a) long sleeve shirts and pants; (b) insulating type shoes (not leather). The technique used by the deceased to repair the microwave oven was also inappropriate. Where high voltage is involved in the repair of microwaves, high voltage testers should be used. The fuse in the high voltage circuit should be tested. A failure of the fuse in the magnetron circuit indicates a failure of the magnetron. A simple magnetic test will indicate operation or otherwise of the high voltage transformer. It is therefore essential that all repairs be undertaken without supply connected in all high voltage situations (microwaves/TV) and testing equipment should be used to check voltage. Graeme Johnstone Deputy State Coroner JANUARY 1991 7 DUAL TRACKING +/- 50V POWER SUPPLY QQQ[t] CHROMAVOX QQQ [t] Automate your light show and let it dance to the music! The Chromavox accepts line input from an amplifier or operates independently, off its builtin microphone. This kit comes complete with a moulded plastic case plus pre-punched silk screened front panel and can handle up to 2400 watts of lighting through 3 channels. $ 139 Cat K-3162 1.5V to 9VDC CONVERTER s149s <at>..i $249 Cat K-3465 12V 100 WATT DC CONVERTER Q Frustrated at how quickly your 9 volt batteries go flat? Then switch over to more cost efficient 1.5 volt cells with this 1.5 to 9 volt converter. It uses just 3 components and fits on a small PC board. This is a short form kit - PCB and components only. Cat K-3230 This power supply can really deliver the goods with variable output from O to 100 volts DC. Ideal for TV servicing. • Variable current to 1.7A<at> 0-87V & 1A<at> 100V • LED indicator for ripple exceeding 5mV p-p • Short-circuit protected • Pre-punched & screened front panel • This kit is supplied complete QQ Ever wished you had the power of your home stereo in the car? Well now you can! This compact inverter will power equipment up to 100 watts. That makes it ideal for our 50 watt and 100 watt amplifier modules. It has temperature and current overload protection plus low voltage shut down to prevent your car battery going flat. This kit is supplied complete including case. Cat K-3235 ~ ~ TRANSISTOR TESTER Q This tester is capable of checking most discrete semiconductor devices, especially bipolars and FETs. It's also an excellent way of becoming familiar with the basic operation of these components. The circuit features an overload indicator and battery check plus a quality meter. Cat K-7220 <at>..i DIGITAL SINE/SQUARE WAVE GENERATOR 1--------------1 DIGIT CAPACITANCE s399s _. 4METER __________________ QQQ[t] This new Digital Sine & Square Wave Generator uses high speed CMOS ICs and a digital filter to produce waveforms over a frequency range of 0.1 Hz to 500kHz. It also features a 4-digit frequency readout, an output level control, and course/fine frequency adjustment. Supplied with pre-punched front panel, case, and all components. Cat K-7350 --------::;;..., Use it in the workshop, use it in the laboratory. This meter can measure capacitance from 1pf to 9999uf in seven ranges. It is mains powered, which means a big bright LED display, and it has an accuracy of better than +1%. Supplied complete with all - components including plastic case, deluxe pre-punched silk screened front panel, QQQ[t] Cat K-7500 rz1 LZJ s149 S129 Kits marked with this symbol involve mains power wiring . Take extreme care when working with this equipment. Degree Of Simplicity Q QQ QQQ Simple Intermediate Detailed I =1 iiiiiiil~ '"' "" '"''''" pl"g ro, t,st lead. ,,,,, .,, BNC ,_,. , ( ~ .:..:... ~ . ..-~~'-• 100 Watt HF Linear Amplifier 10-150 Watt Speaker Protection Relay A wide band HF amplifier with only 3dB drop-off at 28MHz. Use it with any ORP gear with 3 to 15 watts output. Includes carrier operated Rx/Tx switching and a low-pass filter. Cat K-6331 QQQ A universal speaker protection device which can be powered from the amplifier's power supply or used as a stand alone device with its own power supply. Features 'De-thumping' delay with power-up and can be preset for clipping and maximum power level detection. Cat K-4008 WAS Ql1] '249 WAS Oct. '90 s3995 s199 Oct. '90 s29es 30W.Stereo Amplifier RF Attenuator Box From the popular Playmaster series, this 30/ 30W stereo amplifier provides excellent performance, great specs., and low cost. Construction is made easy by mounting all parts, including heatsinks, on one large PCB. Short form kit comes with two TDA 1514 ICs, transformer, PCB, and front & rear panels. Amateurs know just how valuable a good attenuator is ... and how expensive they normally are! Well, here's top value - up to 63dB attenuation in 1dB steps from 50 to 500MHz and it's heaps less expensive than equivalent commercial units! Rated at ¼ watt, with a 50 ohms input impedance and standard BNC connectors. Q Cat K-6323 AEM April '87 QQQ[z] r ~ l,on 1d8-2dB- 4d 8 - 8 d 8 - 1 6 d B - l bd8 - <at>sept.'88 ,') i, Only WAS Battery Power Supply Walkabout Wadio Variable supply - ideal for beginners. No messing with mains, can be powered from a battery. Includes all components, hardware and case. No metering, no frills, but economical. A portable AM radio which can breath live back into that tired AM sound! Using a cunning TRF circuit, the ori~inal audio bandwidth transmitted by the station Is largely maintained and AM comes alive! Cat K-2720 Q QQ mrl17r,,,---=;) WAS WAS s49a5 s14as Oct. '90 Oct. '90 sges s39es Kits marked with this symbol involve mains power wiring. Take extreme care when working with this equipment. Degree Of Simplicity Q QQ QQQ Simple Intermediate Detailed MAJOR DICK SMITH ELECTRONICS AUTHORISED STOCKISTS: N.B.W.: ARMIDALE: - England Electronics 711655 BALLINA: Ballina Electronics 867022 BEGA: OZTECH Electronics 923933 BOWRAL: F.R.H. Electrical 611000 BROKEN HILL: Hobbies & Electronics 884098 COOTAMUNDRA: Cootrnundra Music & Ute 422561 COFfS HARBOOR: Coffs Harbour Electronics 525684 DENILIQUIN: Deni Electronics 813672 DUBBO: Chris's Hi Fi 828711 FORSTI:R: Forster Vill'Wf Electronics 545006 GLEN INNES: John Somme~ad Electronics 323661 =:~m~nm~~.~~~::ic :~=tr:=~i~LL~rr:~1~~n~2?Jii~~~i~!~ ~~p:~~~~i~r~~1Uv~~~rl~ct~~~D~~~~ 7 ="tiicsJil~~ Eloctronics 210722 ORANGE: Central West Electronics 626491 PARKES: Strad Music Cen~e 623366 PORT MACQUARIE: Hastings Computer Service 834574 RICHMOND: SIiicon Crafts 784101 TAREE: Brads Electonics 526603 WAGGA WAGGA: Ptlillips Electronics 216558 WELLINGTON: Welling10n Service 452325 WINDOR: Silicon Crafts 776722 VASS: \Yarmington Electrical 261116 YOUNG: Keith Donges Electronics 821279 VIC: BAIRNSDALE: LH & LM Crawford 525677 COLAC: Colac Electronics 312847 MILOURA: Pullman AUlo Pro 232882 MORWELL: Morwell Electronics 346133 SHEPPARTON: Andrew Electronics 219497 SWAN HILL: ~ District TV Service 329303 TRARALGON: Trara~on Electronics 741699 = ~~t~P;%~;1~~~:1:~~ t;k~i~~~~21~gmiN~~~E::~:~mt Bob ~ ~ l9 " ~ cl ill ri et O] 160!1 gJ -'-l~®00-:')0 sgg Cat K-3~60 ·" ~~~r= Videotronixs 582107 INGHAM: Masons Elecronics 763188 INNISn\lL: lnnisfail Hi.fi 612014 MACKAY: Stevens Electronics 511723 MARYBOROOGH: Keller Electronics 214559 NAMBOUR: N'"1lbour Electronics Shop 411604 PIALBA: Keller Electronics 283749 STANTHORPE Granite Bett Communications 813333 TAB: BURNIE: Eiectonic City 314760 DEVON PORT: A.I.Electronics 248322 BA: MT GAMBIER: Hutchesson's Communication Centre 250400 PORT LINCOLN: BasshMls TV & ~=d2~'f~ ~~~o,A~,J~~nfl~J:i~t% tr'~Jr:"?oo~~~i1:~:v~1~~11 KAIIIATttA: DaYes Osci1ronic 854836 MAl«JRAH: Micro Electronics 581220& PORT HEDLANJ: Ivan Tomek the Elect 732531 RF ATTENUATOR- "" s5ga5 Sm,,.,,.""""'."" Oct. '90 s49es Optical Motion Detector Q Use it as part of an alarm or as a door minder. Detects movement by changes in light level. Operates in two modes 'guard' for sensing movement, and 'search' for beam interruption. O~lys19 95 2 Channel 7 Day Sprinkler Timer DesiQn your own garden sprinkler system for a fraction of the cost of commercial devices! With the aid of a standard distributor tap and one or two solenoid valves, this timer will control up to 14 sectors. The kit is mains powered and comes with a case and pre-punched front panel. You will need to supply your own taps and solenoids. Cat K-3588 QQQ [zj s59es MITH RED HOT SAVINGS ON ADCOLA SOLDERING IRONS! ADCOLA RS50 SOLDERING IRON ADCOLA RS30 16 watt mains powered SOLDERING IRON •• Reliable heavy duty element • 12 watt mains powered • Long-life Triclad 5mm tip • Well balanced design CatT-1825 · Was $ • Long-life Triclad 3mm tip CatT-1820 was $34.95 Save $5 Now only s2995 Now o·n1y• Special offer! - - - - - - - - - - - - - 1 ADCOLA DR30 DUOTEMP ADCOLA RS60 SOLDERING IRON • 21 watt mains· powered • Lightweight, super-slim barrel • Anti-seize 6.5mm tip o-~iy s39 95 Hurry! Limited stocks Fits In The Pocket! BUTANE SOLDERING IRON • Normal plus push-button boost temperature settings! • 21 watts on boost • Can be fitted with a variety of specialist tips CatT-1830 Was $59.00 Now only s43 95 THE PROFESSIONAL 'POCKET' SOLDERING SYSTEM ~-.rr • Pocket sized temperature adjustable Iron (up to 400 deg.C~) • 4 tips including hot knife & blow torch • Heavy duty case with clip on iron -stand • Butane powered- refills in seconds CatT-1374 ECONOMY PENCIL BLOWTORCH Great for heatsink work, silver solder, gold, silver, brazing, glass work, etc. It fits easily in your pocket and is powered by butane gas (the same as they use in cigarette lighters, etc). Cat T-1380 .~•.• •,•,:.;._..,_,N,••••••• • BUY 10 UP AND SAVE! ECONOMY POWER HEATSINK JUMBO BREADBOARD KITS • Flag mounting design with fins top & bottom • Holds 2 x T0-3, T0-26, or T0-220 ICs • Size: 74x102x25mm You'll never have to solder and re-solder experimental circuits again when you have a Wish-Board breadboard kit. • Colour-coded power rails • Phosper bronze & Nickel silver contacts • Aluminium base plate for excellent high frequency performance • Dovetail joints for interlocking boards • Includes assorted hook-up wire, terminal posts, and rubber pads $595ea Cat H-3471 BULK SPECIAL! ONLY 10 or more ~~~~ ; Cat H-4022 NORMALLY This month only! PLASTIC PROJECT CASE s74s5 This new Australian designed case has 3 circuit board slots, a snap fit cover, and provision for bar mounting. Its dimensions are 155x100x75mm. $995 Cat H-2597 Cat H-4042 BULK SPECIAL! ONLY $5.95 ea. on 10 or more NORMALLY PLATED BRASS PCB SPACERS 'fype Round 4BA hole Length 6mm 9mm 12mm 25mm Pack 12 10 8 6 Cat. H-1831 H-1832 H-1833 H-1834 Price $4.95 $4.95 $4.95 $4.95 BULK SPECIAL! ONLY $2.95 ea. on 10 or more Hexagonal $99.95 4BA hole 9mm 12mm 25mm 6 6 4 H-1842 H-1843 H-1847 BULK SPECIAL! ONLY $1.95 ea. on 10 or more BULK SPECIAL! $1.95 ea. on 10 or more se4s5 METAL PROJECT CASE An attractive two-part case with ventilating side slots finished in blue and grey. Dimensions are 160x130x50mm and it's ideal for all your small instruments. $995 Reduced fr ..... .... _,J5 BULK SPECIAL! ONLY $6.95 ea. on 10 or more /l\ $295 This month only! Cat H-2762 HEATSINK TO-3 TYPE POWERFIN For the greatest possible heat dissipation in the smallest possible space. Measures 50x50x26mm. Cat H-3400 $2.95 $2.95 $2.95 $89.95 ~ r--1!6-~ WE'VE GOT CONNECTIONS I CENTRONICS PRINTER CABLES SERIAL CABLES 25PIN SERIAL CABLE DB 25 pin male to 36 pin Centronics. Ideal for Atari St and all computers supporting a PC compatible type parallel port. 25 pin female to 25 pin male. All lines connected straight through. $ Cat X-3564 9T025 PIN SERIAL CABLE Ideal for connecting a modem to a 9 pin serial port. DE9 female to DB25 male connector. Cat X-8007 s24as 2495 Cat X-8614 25PIN SERIAL CABLE For serial port connection. 25 pin male 'D' connectors both ends. All lines connected straight through. Cat X-3574 CENTRONICS EXTENSION CABLE 36 pin Centronics male to female with all connections straight through. Cat X-8617 ADAPTORS s2gas s24as RIGHT-ANGLED PRINTER CABLE Handy 6 foot, right-angled Centronics from DB 25 pin male. Moulded and fully shielded. $ 2495 APPLE/MACINTOSH CABLES PRINTER/ MODEM CABLE SLIM LINE GENDER CHANGERS These revolutionary new slim-line gender changes are only 16mm wide and eliminate space problems caused by standard gender changers. When they're plugged into your existing cable, these gender changers add only 12mm to the cable. 9 male/9 male Cat X-2676 9 female/9 female Cat X-2675 sges sges Apple IIGS, Mac Plus, SE, II/ llx/llcx to lmageWriter 11/LQ or LaserWriter II NT/NTX. 8 pin male to 8 pin male mini DIN. Cat X-2692 s19as Apple IIGS or Mac Plus, SE, 11, llx, llcx adaptor cable. 300mm cable. DE9 female to 8 pin male mini DINs, Cat X-2693 gas Cat X-2678 GET INTO ALL THE RIGHT CONNECTIONS TODAY! AT DICK SMITH ELECTRONICS B1072/P2 SERVICE AIDS 5 MINUTE EXPOXY ECONOMY HEAT A hard wearing expoxy glue for TRANSFER COMPOUND situations requiring a gap filling ·A silicon based compound in an economical 10g plastic tube compound. Comes in an easy to use 24ml double syringe. Cat N-1228 cat N-1205 s295 Sll.ASTIC 732RTV CONTACT ADHESIVE Acid curing Silastic 732RTV seals and insulates rubber, wood, glass, and metal Cat N-1225 SUPER GLUE SUPER GLUE REMOVER Just the thing for emergency repairs to any non-porous material. 2ml tube. Cat N-1217 You don't have to be stuck with a problem! A safe Super glue remover in a 10ml container. Cat N-1221 $195 s495 HOBBY SUPER GLUE PVA GLUE Superfast super glue in a 10ml bottle The easy to use adhesive that gives for instant repairs! a lasting but flexible bond between a Cat N-1219 large range of materials Cat N-1222 S595 , s295 Ideal for wood, cloth, leather, or any porous material. 50ml bottle. Cat N-1223 ,,, s3so · ··.. PANEL METERS ....,. Universal Range These universal panel meters can be easily adapted for any scale of Volts, Amps, or Ohms. By combining them with our SHUNT PACK they will be capable of operating over the range 100uA to 10A or 1V to 100V. Small MU-45 Type- (lOOUA) Scale size: 55x30mm Overall size: 58x52mm Cat Q-2045 ... s1&95 Medium MU-52E Type- (lOOuAJ Scale size: 75x36mm Overall size: 80x66mm $ Cat Q-2055 • • BENCH METERS 1995 With extra large sloping scales and a wide viewing angle, these are the perfect meters to leave 'in circuit' while you probe around with your multimeter Cat 0-2140 Volt Meter Cat Q-2130 Ammeter Large MU-65 Type- (lmAJ Scale size: 96x49mm Overall size: 100x82mm Cat 0-2060 s2195 Shunt PackShunt resistors from 1.1 to 1,000,000 ohms plus resistance wire and instructions. Cat 0-2046 s195 Only s19 95 aac11 Save $10! DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to OS XPRESS, PO BOX 321 N/RYDE NSW 2113 PHONES SECURITY AUDIO COMPUTERS All Major Credit Cards Accepted. 0/Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Brookvale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 4111955 • Chullora 642 8922 • Gore Hili 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcasne 611896 • North Ryde 878 3855 • Parramana 689 2188 • Penrith 32 3400 • Railway Square 211 3777 • Sydney City 267 9111 • Tamworth 661711 • Wollongong 28 3800 •ACT• Belconnen (06) 253 1785 • Fyshwick 80 4944 •VIC• Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St3266088and 246 BourkeSt6390396 • Richmond 4281614 • Ringwood 879 5338 • Springvale 547 0522 • QLD • Brisbane City 229 9377 •Buranda 391 6233 • Cairns 311 515 • Chermside 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 •SA• Adelaide City 223 4122 • Beve·ley 347 1900 • Elizabeth 255 6099 • Enfield 260 6088 • St. Marys 277 8977 •WA• Cannington 451 8666 • Fremantle 335 9733 • Perth City 481 3261 • Midland 250 1460 • Northbrid e 328 6944 • TAS • Hobart 31 0800 •NT• Stuart Park 81 1977 The Largest Australian Electronics Retailer! 63 Stores Across Australia B1072/MM - ectr,c The state of the art With the Solar Challenge race from Darwin to Adelaide now an international event, the prospects for electric vehicles in the future are looking decidedly rosy. But while solar electric vehicles are progressing rapidly, is the same true for conventional electric vehicles? By GERRY NOLAN Zero to 100km an hour in 6.5 seconds! Neck snapping acceleration with a just a rush and a whirr! Smooth, almost soundless, electric driving over a range of 200 kilometres at 90km/h for a fuel cost of around $6.00. That's only 3 cents per kilometre! Compare this with fuel costs of about 8 cents per kilometre for the family car at today's prices and it all sounds too good to be true. These things may to be true of electric vehicles in the future but don't rush out to your local dealer and try to buy an electric car that will turn in these performance figures today. Such a vehicle just isn't available. Recently though, I rode with David Gosden, director of the Sydney University Electric Vehicle Research Facility. He was at the wheel of their electric van, a Suzuki Carry Van with a highly modified Pope electric motor. This EV (electric vehicle) recently gained full registration with the NSW Roads and Traffic Authority for road use, a significant milestone in the 14 SILICON CHIP project which was conceived by David in 1987. Driving in the van, the initial impression is definitely not one ofnecksnapping acceleration; more one of surprise. After a few seconds wait while the Toshiba portable computer tells the controller what is expected of it - part of the "teaching" process that will later be encoded into the unit's own microprocessor - there are two decisive "clunks" as the contactors make, the computer is unplugged and put away and ... we're moving! There is no prelude to moving off, no whine of the starter or revving of the engine, no quick 'blip' of the accelerator. It's just - well - suddenly you're moving, smartly but smoothly. There is the expected whirr, but road noise, which in a conventional car is usually drowned by engine noise, is more intrusive than expected. No, the impression is not one of speed. It is more like the inexorable movement of an electric train but without all the noise. Of course, electric vehicles are not new. In fact, they were around before internal combustion engine (ICE) vehicles and for many years were direct competitors with them. Between 1902 and 1911, Studebaker alone made around 2000 electric cars and trucks. , I well remember riding the electric trolley buses that plied the streets of Adelaide in the 1950s and of course every city underground railway is electrified. Electric vehicle advantages The reasons for choosing EV s over ICE vehicles read like a shopping list for improving the environment: (1). Reduction of noxious emissions, especially in urban environments; (2). More efficient use of available energy; LEFT: THE GREEN MACHINE . the electric-powered Suzuki Carry Van looking as though it has just come back from a suburban shopping trip. This picture was taken just after it received full registration from the NSW RTA. The Sydney University Electric Vehicle Research Facility project is sponsored by Pope Electric Motors, the Electricity Commission, Exide Batteries, Traction Controls and Siemens Ltd. drive, as we approached a pedestrian crossing, one of the potential problems of electric vehicles manifested itself - it was very obvious that noone had heard us! David Gosden said that it's something he has to be alert for all the time he is driving the EV. Perhaps we'll have to resurrect those red flags that had to be carried along in front of the original horseless carriages! Why aren't they popular? PHOTOGRAPHS BY ROBERT McDONNELL (3). Reduction of audible noise in urban areas; (4). Reduced consumption of petroleum; and (5). Greater flexibility of vehicle design and reduc.e d vehicle maintenance costs and times. One of the main objections to EVs has been that they "don't have anywhere near enough range between recharges". Like a lot of such objections, this one is usually based on gut feeling rather than facts . Surveys have shown that around 90% of all daily one-way car trips are less than 35 kilometres long and over 50% are less than 10 kilometres long. Most of these trips are made at a low average speed and with relatively low acceleration. Also, typically the urban vehicle carries an average of only 1.2 persons. The Sydney University Suzuki is designed for a top speed of l00km/h and a range of 100km without recharging. This 100km range is expected to later increase to 130-140km with the addition of solar cells. Obviously, EVs are suitable for many driving requirements. Nevertheless, when all things are considered, including some of the technological developments we will be discussing over the next few issues, the conventional motor vehicle Will probably show an advantage over the EV for quite some time to come. However, the twin considerations of greenhouse effect and the depletion of oil supplies raises the reduced consumption of petroleum and low emissions of EVs to paramount importance. Just a few hundred metres into our Apart from the politics surrounding the production of conventional ICE vehicles, there are immense infrastructures for producing, distributing and using them and an enormous investment in plant, equipment and human skills. These create massive inertia which must be overcome before a different technology, like electric vehicles, can be implemented. For the same reason, lead acid cells will continue to be manufactured despite other types being more efficient. The overwhelming majority of people don't even think of electric vehicles as an alternative - yet. It is even doubtful that many realise that the exotic, high-profile solar powered cars are actually electric vehicles us. ing the latest technology in computer design, batteries, motors, controllers, construction materials and even tyres. Continued finance for research and the. acceptance of EVs both depend on increasing public knowledge and awareness. Today more and more people worry about environmental deterioration and hope that governments will do something about it. When they realise that EVs are a viable alternative they will put pressure on their governments to favour EVs and to penalise conventional vehicles. For example, a city council may put a tax on all conventional motor vehicles entering the city boundaries JANUARY 1991 15 A CLOSE UP VIEW of the battery ventilation intakes under the registration plate of the Sydney University EV. The battery compartment must be well ventilated to make sure that hydrogen does not build up. UNIQUE MOBILITY'S MODEL M-91 hybrid electric vehicle prototype is a modified Chrysler minivan which uses a small petrol engine powered generator to charge the batteries. This extends the driving range to more than 160km. BATTERY TRAY UnlQ ELECTRIC DRIVE UNIQUE MOBILITY'S M-91 hybrid vehicle uses a large removeable battery tray and the electric motors drive the front wheels. 16 SILICON CHIP THE DRIVING COMPARTMENT in the Suzuki van looks quite normal, even to the "ignition" switch! Despite the fact that the vehicle has no ignition, this key-operated switch is a requirement for registration. There is no clutch; just the go and stop pedals. The lever with the round black knob between the seats is the forward/ reverse selector. The instruments and warning lights are in the neat console above the radio. while, at the same time, state governments might reduce registration and insurance costs for EVs and add an "environment" tax to ordinary vehicle registrations. As far as the introduction of EV s is concerned, initially municipalities will lt::ad the way, then utilities and other delivery and service organisations. Eventually, electric vehicles will become the accepted means of individual commuting transport and then family transport. As stated above, growing city pollution fears, the greenhouse effect and oil supply worries have provided a new impetus to EV development. Figures released by the South Coast Air Quality Management District in Los Angeles and shown in Table 1 compare emissions from an internal combustion eI).gined (ICE) passenger car with EVs, including power generation, for every 100,000km travelled. These figures show that, in total, electric vehicles are 98% less polluting than ICE powered cars, per kilometre travelled. Early in September 1990, the city of Los Angeles awarded a $7 million contract to the Swedish Clean Air Transport Company, with another $7 million expected to go to Unique Mobility, a Colorado company, for the design and engineering work to eventually produce 30,000 electric vehicles by 1995. These are intended for use in private and public fleets throughout the city. Municipal authorities may lead the way but no matter how economical and pollution-free electric vehicles may seem, the average motorist will not accept them until they lose their "clunky" image and offer similar performance for about the same price as ICE powered cars now do. L00KING INTO THE REAR of the van gives a clear impression of the size of the lead-acid battery compartment and the great strength that has been built into it. The size could be reduced to less than half by using more recent battery developments such as silver-zinc, but at much higher cost. The battery charger is mounted on the side of the van to the left and the compartment exhaust fans, used to vent hydrogen during charging, are below the reversing light. The large panel with heatsinks and capacitors is the power control panel. Perhaps this is just around the corner. General Motors in the USA claim acceleration figures of 0 to lO0km/h in 6.5 seconds and a range of 200 kilometres at 90km/h for its 2-seater Impact car. And they say that it is ready to go into production as soon as there is sufficient demand. These greatly improved performances have been made possible by the exciting combination of recent developments in energy storage, rareearth magnet motors, electronic motor control technology, on-board computers, materials technology and by the dedicated group of people who have continued to work steadily on electric vehicles while they have been out of the news. Two key factors in improving electric vehicle performance are energy to weight ratio (energy density) of the storage system and power to weight ratio of the motor and controller. When you realise that one kilogram of petrol stores the equivalent of 12,000 watt-hours of energy while the trusty lead acid cell can only offer up to 50 watt-hours per kilogram, it is obvious that electrical energy storage JANUARY 1991 17 Block Diagram of a Typical Electric Vehicle {EV) Drivetrain WHEEL SPEED OR POSITION DRIVER ELECTRICAL INPUT, EG ACCELERATOR PEDAL CONTROL LOGIC CURRENT LEVEL REAR AXLE ENERGY STORAGE DRIVESHAFT POWER CONTROLLER DRIVE MOTOR DIFFERENTIAL ENERGY STORAGE SYSTEM FIG.1: THE POWER TRAIN of a typical electric vehicle. In the future, it seems likely that electric vehicles will use mains power and solar cells to keep the batteries charged. One of the main areas for innovation is in transmissions. The electric motor may be used to replace an internal combustion engine, driving through the existing tailshaft & differential, or it may be connected through a chain drive or geared belt to the rear wheels. systems have a long way to go to compete. In fact, there is an enormous research effort into energy storage worldwide with, it seems, everyone looking at every possibility except lead-acid cells. Some of the combinations available, with their energy <lensities in watt-hours per kilogram in brackets, include: aluminium-air (300), nickel-iron (60), nickel-zinc (90), zinc-chlorine (90), nickel-cadmium (30), silver-zinc (100), lithium metal sulfide (170) and sodium-sulfur (300). Other high temperature batteries, fuel cells and hybrid batteries are also being researched, as well as batteries that use liquid vanadium of different valences as electrodes, which are simply replaced to recharge the battery. Flywheel energy storage Flywheels have also been used in vehicles for energy storage since the 1930s and as far back as 1973 researchers were predicting energy 18 SILICON CHIP densities of 870 watt-hours per kilogram using fused silica as a material for super flywheels, Although research is still going on, neither the fused silica or the high energy densities have materialised. Nevertheless, the availability oflight, high-tensile fibres, magnetic levitation bearings, high vacuum enclosures and electronic commutation and control have enabled flywheel energy densities of more than 40 watt-hours per kilogram to be obtained. After the storage system, the next links in the EV power chain are the motor and its controller, both of which have progressed rapidly in recent years. Rare earth magnets Brushless permanent magnet motors, both AC and DC, now use rare earth magnets such as samariumcobalt and neodymium-iron-boron (Nd-Fe-B) with sophisticated Mosfet controllers to replace sliprings and commutators and to permit precise control over motor speed and torque. Readers familiar with the greasy end of electronics will remember that series DC motors, while having high starting torque, have very poor load/ speed regulation, And DC shunt motors tend to have very good load/speed regulation but do not have high torque at start up and suffer from very high starting currents, Permanent magnet motors are virtually equivalent to shunt DC motors in this regard. But now, by using electronic motor controllers, torque and speed characteristics can be optimised. Until recently too, both AC and DC motors needed brushes and sliprings or commutators that required careful bedding in and frequent maintenance, as well as being inherently inefficient. They also produce considerable radio frequency interference (RFI) and are difficult to cool. With electronic commutation, brushes and sliprings are eliminated. Using a permanent magnet rotor insteai:l of a wire wound rotor also cuts out FR losses in the rotor. DC permanent magnet motors with peak efficiencies of up to 97% and power to weight ratios of up to 3,000 watts per kilogram are actually in production. An example of these are the UNIQ motors, produced by Unique Mobility in Colorado USA. These were used to power 18 of the You Can Now Upgrade to EGA Graphics For Less Than $600 Only the first 100 orders at this price Purchase this EGA Color Monitor for $599.00 and we'll give you the control card FREE EGA MONITOR This EGA full colour monitor provides both text and graphics capability with all EGA interface cards. It has a dot pitch of 0.31 mm picture tube which also features a anti-reflective coating. The other feature you will fi nd very useful is the tilt and swivel stand. CAT ACMEGA Normal Retail Price $794.00 If you have an EGA Monitor and only need a Control Card LESS THAN COST, NORMAL PRICE $199.00 YOU PAY ONLY: $75.00 EGA Card with Monochrome Mode This enhanced Graphics adaptor is designed to upgrade the graphics display of the IBM PC XT/ AT and compatibles to a high resolution display. There is 256K of standard video memory provided, and it is also fully compatible with the IBM Monochrome Display Adaptor (MDA), Hercules Graphics Adaptor (HGA) as well as the Colar Graphics Adaptor (CGA). You also will not have any problems operating this card up to 16MHz. The DIP switches allow the card to Mono, CGA or EGA. No special modifications are necessary to operate in high resolution mode of (640 x 480) with software such as WINDOWS, WORD and CHART from Microsoft, AUTOCAD from Autodesk, LOTUS 1-2-3 from Lotus Corp., VENTURA from Ventura software and other popular software packaages. IAN'S PERSONAL GUARANTEE * All products carry a 14 day money back guarantee ( except software and hard disks). * All prices include sales tax. * All motherboards carry a full 12 month warranty. * All other products carry a full 3 month warranty. WHOLESALE ENQUIRIES WELCOME Due to Technical advances, products we supply may in some cases vary from those pictured. In all cases the products supplied are guar- t~;;::n:~::;.;og~s::g:,:::::d::.:;.::.::11.,i:i15==-=-~,., I I I I I I this coupon to receive your copy. Mr/Mrs/Ms: Address:._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Suburb: State:._ _ __ _ Postcode: I I I I I I ~--------------------------~ . Electronic Solutions I 5 Waltham StArtarmon 2064 PO Box 426 Gladesville 21 11 Telephone: (02) 906 6666 Fax: (02) 906 5222 32 entrants, including three of the top four finishers, in the July 1990 Sunrayce from Orlando, Florida to Detroit, Michigan. A similar number were used in the second World Solar Challenge race in November, from Darwin to Adelaide. Its very high power density makes the UNIQ motor ideal for solar powered vehicles and other applications where size and weight have to be kept to a minimum and efficiency is essential to reduce energy consumption. (Editor's note: motors with even higher power densities are now being used in electrically powered model aircraft. For information on this topic, see Bob Young's article on Remote Control in the November 1990 issue of SILICON CHIP). The powertrain As with conventional ICE vehicles, there is a minimum number of elements required to get the energy from the storage unit to the wheels. Called the "powertrain", it is formally defined as the electromechanical system between the vehicle 's energy source and the road. In the case of electric vehicles, we also need a path to get the energy from the wheels back to the storage unit during regenerative braking. For the purposes of future discussion, we will define an electric vehicle as one in which the tractive effort is supplied by an electric motor and the energy source is portable and electrochemical or electromechanical in nature. Fig.1 shows the powertrain of a typical electrical vehicle. Any one or A MAJOR DIFFERENCE between the electric vehicle and the ICE vehicle is the male socket for connection of 240VAC mains power. 20 SILICON CHIP THIS VIEW SHOWS the UNIQ brushless DC motor and its controller. A motor like this, 163mm in diameter and 147mm long, has a 15kW (20HP) power rating. all of the elements may be varied in themselves and related or matched to each other in several ways, depending on the requirements of the designer. From the diagram we can see that the elements in the direct chain are: (1) energy source; (2) energy storage; (3) power controller - with inputs; (4) drive motor; (5) transmission; and (6) wheels. The powertrain may vary at almost every point in the diagram. For example, in a solar powered vehicle, the energy storage charger is naturally the bank of solar cells on the roof instead of a mains powered unit. In a hybrid electric vehicle, the energy source is likely to be a small petrol power generator which continually charges a small battery and also drives the electric motor directly. The drive controller will vary depending on the budgetted price for the vehicle and it may or may not incorporate circuitry for regeneration (ie, charging the battery) during braking. Similarly, depending on price constraints, the drive motor could be AC or DC, brush-type or brushless. One of the main areas for innovation is in the area of transmissions. The electric motor could possibly just drive the existing tailshaft and differential of a conventional vehicle or it could be directly connected to the wheel(s) via gearing, a chain drive or belt drive. No matter what the details of the drivetrain, future electric vehicles are likely to look fairly similar to the vehicles we are driving today. Syd- TABLE 1 Emission Reactive organic gases Carbon monoxide Nitrogen oxides ICE kg 745 731 49 EVs kg 1.5 2.6 18 ney University's electric vehicle seems to carry this to extremes. For example, the driver's compartment looks quite normal, even to the extent of having an "ignition" key. Despite the fact that the vehicle has no ignition system, this key operated switch is still a requirement for registration. There is no clutch of course, just the go and stop pedals. And in place of the normal gearbox lever, there is a forward/reverse lever, mounted between the seats. On the other hand, most of the cargo compartment is occupied by the large battery box. The size of the battery could be reduced to less than half by using more recent battery developments such as silver-zinc, but at much higher cost. The battery charger is mounted on the side of the van to the left and the compartment exhaust fans, used to vent hydrogen during charging, are below the reversing light. Future articles. will look at batteries and flywheels; electronic power controllers; electric motors and the new generation of power transducers; transmission systems and wheels; and the future of electric and solar electric vehicles in Australia. SC Welcome to 1991 with Great Bargains From SHERIDAN ELECTRONICS 5k JOYSTICK POT MECHANISM DIGITAL PHONES WITH 10 MEMORY - NEAR NEW NEW WELLER TIPS $2.50ea SUITS XT or ~T IB~ Compatibles $49.95 $4.50ea 1-2mm 315C Suits WTCAN Soldering Station & 32mm 370C For Pencil Iron 360K D/S DISK DRIVE Limited Quanity at this Price $1 O OOea . Just about as cheap as a Cleaning Kit ■ WELLER SK140-6-TCP Cable Weld Tip - Can be used as a Replacement Barrel NATIONAL RECHARGEABLE "N" CELL 1.2V 150mA ' $1.95e-a SUPER POT PACK Over 100 Values. Includes Sliders, Switches and Rotary Pots $5.00ea 1O,OOOuF 40V ELECTRO'S $100 Value for only $10.00 30 ASSORTED RELAYS 12VDC BRUSHLESS FANS Includes 24, 12, 6 & 2 volt as well as Reed Relays. 80mm x 80mm You have seen our competitors price compare this $9.95ea VERNIER REDUCTION DRIVES Don't Pay $15.50 Well over $90 Value for only $9.95 9" 12VDC 30Hz TTL GREEN SCREEN Complete with Deflection yoke & Driver Board, as well as Data Our Price $9.95 ONLY $4.50ea 2N301 Transistor Germanium TO3 $ 1.00ea. 1N4002 Diodes 100 per pack $ 3.00 Telephone Cable 6 Way & 4 Way $ 0.40mtr UHF TRANSISTORS 2N5946 4W $ 8.00ea 2N5947 10W $10.00ea 2N6136 25W $12.00ea Data ia available for these transistors 1/4" Shaft Knobs $0.50ea SHERIDAN'S WILL BUY YOUR SURPLUS STOCK •· '~ DISK DRIVE POWER SUPPLY 17 volt 3.4A, 8.5 volt 6.8A , BRAND NEW $19.95 NICAD CELL TESTER Worth at least $60.00 ONLY $19.95 $39.95ea PERSONAL SHOPPERS ONLY SCOOP PURCHASE TRANSFORMERS 240 Volt Primary 16 Volt Secondary 5 Amp Continious NORMALLY $34.00 YOU PAV ONLY $13.50 SHERIDAN ELECTRONICS, 328 ELIZABETH ST, (Cnr Kippax St. opp. Central Station & Dental Hospital) SURRY HILLS, NSW, 2010 TELEPHONE: (02) 281 7727 33 CHALLENGING COMPUTER GAMES FOR TRS80/ APPLE/PET 57 PRACTICAL PROGRAMS & GAMES IN BASIC ALL ABOUT HOME SATELLITE TELEVISION ALL ONLY $3.95ea [Z] 1~1 ~ SHOP HOURS: MON - FR/ SAT 9.00am - 5.30pm 9.30am - 12.00pm JA N UARY 1991 21 Have fun with the Fruit Machine Step right up, folks. Try your hand at the amazing Fruit Machine. You can use it just like a poker machine but you don't have to go home in the evening flat broke. There is a jackpot and other winning combinations. Design by BRUCE BAGULEY "Gambling is a curse" , they say and it certainly sends many people broke every week. Whether you enjoy playing poker machines or wish to demonstrate their futility, you can have fun building and playing with the Fruit Machine. It is economical to build and requires no coins to be fed into it to play! Designed by Bruce Baguley, of Kotara High School in NSW, the Fruit Machine is also a good exercise in electronic principles. It uses timers, counters and decoders to drive three ?-segment LED displays. The LED displays are not wired to show digits but to show letters of the alphabet. As wired, they can show "A" (for Aces), "O" (for Oranges), "C" (for Cherries) and "L" (for Lemons). There is one jackpot combination and five other winning combinations of these displays. The jackpot is three Aces (AAA) which, according to the front of the Fruit Machine, gives a payout of 1000 points. No money changes hands, of course, but it is nice to keep score. Other winning combinations are as follows: 000 (3 Oranges) - 150 points; CCC (3 Cherries) - 20 points; LLL (3 Lemons) - 10 points; and AA (2 Aces - 5 points. All other display combinations are losing, which is to say that they don't win any points. Sad. Ergonomic features As presented by the designer, the Fruit Machine is built into a small wooden enclosure which looks like a miniature poker machine. There is a long lever on the righthand side to play the unit but apart from that, there is no on/off switch or any other controls. The front panel has the three red LED displays in a transparent window and the winning combinations are printed for easy reference. All you have to do is plug in a 12V DC plugpack and you are ready to play (but not lose your shirt!). The circuit The circuit of Fig.1 looks pretty large but it is basically a smaller circuit repeated (almost exactly) three times. So to fully describe the whole circuit, we only have to describe a third of it. So let's have a look af the top section of the circuit, The prototype was built into a small wooden case & fitted with a handle, just like real pokies used to have. You can play it just like the real thing but it won't send you broke. 22 SILICON CHIP Fig.1 (right): the circuit consists of three almost identical sections, each based on a 555 timer, a 4017 decade counter & an FND500 7-segment display. When the play button is pressed, the 555 timers clock the decade counters & these then drive the segments of the displays via decoding diodes & driver transistors. + 270k_ 16 V+ 390!! 390!! 390!! 3 14 IC2 4017 a 03 BC548 E 6 C1 01! ef d fc FND500 2d 05 BC548 E 15 .,. + a 4C 04 BC557 C 13 ,,-:-,b 6 b 10 .., 16 470k 390\! 390U 390\! 14 IC4 4017 08 BC548 E 6b 4C FN0500 0.1 ! +12VO FROM PLUG-PACK 09 BC557 C V+ 01 1N4002 2d 9 ® g 15 010 BC548 10 .,.8 .,.. o* + 9 I a 16 680k 390U 390\l 390\l 390\l ~1 S1 IC6 4017 9 013 BC548 E 14 0.1+ FND500 + 2d B "'""& SPEAKER.,. EOC VIEWED FROM BELOW 13 15 10k g 10 B .,. .., FRUIT MACHINE JANUARY 1991 23 PARTS LIST 1 wooden case (see text) 1 PC board, code SC08101911, 138 x 102mm, 1 lever assembly (see text) 1 microswitch (S1) 1 50mm an loudspeaker 1 2.1 mm DC socket 1 12V DC plugpack and matching DC plug 30 Molex pins Semiconductors 3 FND500 common cathode red LED displays 3 555 timers (IC1, IC3, IC5) 3 4017 decade counters (IC2, IC4, IC6) 9 BC548 NPN transistors (02, 03,05,07,08,010,012, 013,015) 6 BC557 PNP transistors (01, 04,06,09,011,014) 1 1N4002 silicon diode (D1) 21 1N914, 1N4148 silicon diodes (D2-D22) Capacitors 1 100µF 16VW electrolytic 3 1µF 16VW electrolytic 3 0.1 µF 160VW metallised polyester (greencap) Resistors (0.25W, 5%) 3 3.3MQ 15 10kQ 1 680kQ 15 3900 1 470kQ 1 470 4270kn 24 SILICON CHIP involving Ql, ICl, IC2 and an FND500 7-segment LED display. In essence, this circuit consists of a free-running oscillator (ICl), a decade counter and a diode decoding net'l(Vork to drive the 7-segment display. Let's look at the decade counder, IC2, first. It is a 4017 with 10 individual outputs, which go high successively. In our circuit, we are only using six of these outputs and these are connected to a decoding network consisting of seven diodes, D2-D8. These drive four transistors, Q2-Q5, which then drive the a-g segments of the display. Display decoding Let's see how the transistors and diodes produce the various displays. For example, to give the display "L", segments 'e', 'f' and 'd' need to be lit. Segments 'e' and 'f' are connected together and permanently connectec:l to the positive supply via a 3900 re'~ sistor. So the 'e' and 'f' segments are on all the time. For the 'd' segment to be lit, Q4 Below left: push all the parts down onto the PC board as far as they will go before soldering their leads. The three FND500 displays are mounted on Molex strips, as described in the text. After assembly, the completed board is secured by two screws to wooden blocks in the back of the case, as shown in the view below right. must turn on and so its base must be pulled low by pin 9 of IC2. This pin will be low for 9/loths of the time, so the 'd' segment will be on for the same amount of time. This makes sense because the 'd' segment needs to be lit to produce the "C", "L" and "O" displays. The 'a' segment is driven by QZ, an NPN transistor. For QZ to turn on, either pin 1, 3, 4, 6, 7 or 9 of ICZ needs to be high and so cause the relevant diode(s) (DZ-D8) to conduct. So the 'a' segment will be on for 6/loths of the time. Again, this makes sense because the 'a' segment needs to be lit to produce the "A", "O' and "C" displays. Now consider the 'b' and 'c' segments. These are connected together and driven by Q3, another NPN transistor. Q3 is turned on whenever pins 6, 7 or 9 are high. The 'b' and 'c' segments need to be lit to produce the "A" and "O" displays. For its part, the 'g' segment is driven by Q5 and it can only turn on when pin 9 of ICl is high. From the above , we can see that to produce the "A" display, we need all segments on except the 'd'. So to get an "A" display, Q4 must be off (segment 'd' unlit) and QZ, Q3 and Q5 must all be on. This condition only occurs when pin 9 of ICZ is high. Get the picture? Similarly, to obtain an "O" display, all segments except 'g' must be lit. For this to happen, Q4 must be off and the three TO S1 three separate circuits. By now, you will probably have noted that the three separate circuits are very similar. There are in fact, only two points of difference. One involves the resistors associated with the lµF capacitor. In the case ofQl, there are 3.3MQ and 270kQ bias resistors. In the case of Q6, the resistors are 3.3Q and 470kQ, while for Ql 1 the resistors are 3.3MQ and 680kQ. These larger resistor values mean that Q6 stays on for a little longer than Ql, while Ql 1 stays on for a little longer than Q6. In practice, this means that the LED display associated with Ql stops first, followed by the display for Q6 and then the display for Ql 1. This simulates the action of a real poker machine whereby the reels come to a stop in succession. Noise source SPEAKER Fig.2: check that all parts are correctly oriented when installing them on the PC board, especially the transistors. Also, be sure to use the correct transistor type at each location. When mounting the FND500 displays, make sure that the decimal point is at lower right. other transistors on. This condition only occurs when pin 6 or pin 7 of IC2 is high. So we can already see that there is a "time bias" in the circuit and that the "O" display will be lit-for somewhat less time than the "C" display and the "A" display will be on for the least amount of time. So far then , we have seen how IC2 and the following components produce the various letter displays. We now look at IC1 which functions as the clock for IC2 . IC1 is a 555 timer connected in astable mode. When Ql is turned fully on, IC1 will feed clock pulses into pin 14 of IC2 at a frequency of about 3Hz. The lever switch Ql is turned on whenever the Play switch Sl is closed. This pulls the base of Ql low via the 3.3MQ resistor and charges the associated lµF capacitor. When the Play switch is released, the lµF capacitor then keeps Ql turned on until it discharges via the base bias resistors. It is at this point that we need to talk about the differences between the The other differe nce in the three circuits is that IC5 , a 555 timer and clock source for IC6, drives a loudspeaker via a 47Q resistor and lO0µF capacitor to give some "action" sound - a stream of clicks of decreasing frequency as the circuit winds down. Power for the circuit comes from a standard 12V DC plugpack via diode Dl which provides protection against reverse polarity connection. Construction As noted above, the Fruit Machine is housed in a small wooden case and the circuit is installed on a PC board measuring 138 x 102mm and coded 08101911. As much as possible, the components on the board have been lined up in rows which tends to make assembly easier. All the ICs and diodes face in the same direction but the transistors do not, so some care will have tobe taken when installing them. RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 No Value 4-Band Code (5%) 5-Band Code (1%) 3 1 3.3MQ 680kQ 470kQ 270kQ 10kQ 390Q 47Q orange orange green gold blue grey yellow gold yellow violet yellow gold red violet yellow gold brown black orange gold orange white brown gold yellow violet black gold orange orange black yellow brown blue grey black orange brown yellow violet black orange brown red violet black orange brown brown black black red brown orange white black black brown yellow violet black gold brown 4 15 15 JA NUA RY 1991 25 The Play microswitch is activated by a screw which is secured to a brass rod handle via a bush. This view shows the switch in the open position. We would suggest that the PC board be assembled first and checked out for correct operation. After that, the wooden box can be made. The first step in assembling the board is to check that it has no defects such as undrilled holes, shorts between tracks or open circuits (breaks) in tracks. You can check the board against the pattern published with this article. When the handle is pulled, the brass rod rotates & the screw closes the microswitch. The spring then returns the handle to the rest position when it is released. You can then start by fitting all the diodes and the resistors. The full wiring diagram is shown in Fig.2. To make subsequent checking of your work easier, install the resistors so that their colour codes all run in the same direction. This done, install the three wire links and the six ICs, then insert the three 0.1µF capacitors and the four electrolytic capacitors, making sure that the latter are all in- stalled the right way around. Now the transistors can all be installed. Those for the displays all face in the same direction except the BC557 PNP types which face the other way. Lastly, the three LED displays can be installed. These are not directly soldered into circuit but are inserted into sockets made from Molex connector strip. You can buy this connector strip in long lengths. You just snap off the lengths you want, 5-pin in this case, solder them into the PC board and then snap off the top sections. When installing the three LED displays into their sockets, make sure you install them the correct way around. When upright, the decimal point for each display should be in its correct position. Note: the decimal point is not used in this circuit but you still have to put the dis- Fig.3: this is the full-size artwork for the PC board. You can use it to etch your own board or to check that the board you receive has been correctly etched. 26 SILICON CHIP 48 ◄ 40 Fig.4: this diagram shows the dimensions of the wooden case used to house the prototype. The front & back panels were made of Masonite, while the side panels & spacers were made of pine. I ~-i---- - -----,:_-_ iI I I r-- --~ I [ ] i I Cl - 2xWOOD SPACERS 12x12x40 I I I I C, "" I I I I I DIMENSIONS IN MILLIMETRES play in the right way otherwise it won't work. Now you ready to check the PC board for correct operation. If you want to, you can install a pushbutton switch temporarily on the board to function as a Play switch. You can also temporarily connect a speaker so that you can have sound. . Now apply power to the circuit. The three LED displays should light up and they should all give one of the designated letters; ie, A, 0, C or L. Our prototype powers up with three Ls. Now operate the Play switch and observe that all displays cycle and that they come to a stop in sequence, first the lefthand display, then the centre one and last, the righthand display. The speaker should also make a clicking noise which slows down and stops when the lefthand display comes to a stop. That being the case, you can set to and make a box for the unit. The prototype was made with sides of pine and the front and back panels of Ma-sonite. The front Masonite panel was glued in place while the rear panel is held on with a couple of woodscrews. The PC board is supported on a pair of woodspacers 12mm thick, immediately behind the front panel. The full details of the timber case are RCS Radio Pty Ltd is the only company which manufactures and sells every PCB E, front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. shown in the diagram of Fig.4. As far as the Play switch is concerned, you have two options. You can take the easy way out and just have a pushbutton switch mounted on the printed board and protruding through the front panel; or you can do it with a a little more style and make a lever switch. The lever on the prototype was made from 5mm diameter brass rod bent at rightangles and passed through both sides of the box. A bush was mounted on the horizontal shaft and arranged to trip a microswitch mounted on the side of the case (see photos). The knob on the lever was a plastic ball 21mm in diameter and drilled to be a tight fit on the rod. The 2.1mm DC socket was mounted on the back panel. The front panel was made quite simply. A layer of red Cellophane was placed over the Masonite panel and held in place with adhesive tape. Then a photostat copy of the front panel artwork was coloured in (yep, with colouring pencils) and glued over the panel. The whole lot was then given a protective coating with a clear layer of Contact covering (simple, but effective). SC JANUARY 1991 27 Pocket Sized Sine/Square Signal Generator 01542 • Frequency Range: 20Hz to 150 KHz. Times 1; 20Hz to 1.SKHz. 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WAS S/49.00 NOW $120.00 SAVE e . e True RMS AC dB Meter -45<1B Impedance• 3.5 Digital Display• AC Volt tOOuV-tOOOV e DC Amp/ • Resistance 0.1O·20Mae Diode Buzzer • Automatic Polarity Rever X 2110 20MHZ $19.50 ANOTHER GREAT NEW ALTRONICS IMPORT DINKY DESK CALCULATOR $100 FREE BONUS OFFER . • 8 LARGE DIGITS 10mm HIGH • SUPERB FEEL, TACTILE BUTTON KEYS • BEAUTIFUL ERGONOMIC DESIGN 12 x 6cms Q 0156 LABTECH DUAL TRACE OSCILLOSCOPE COMPLETE WITH TWO 10:1 PROBE KITS. NORMALLY $899.00 DAZZLING NE MODEL FOR '91! THIS MONTH ONLY $799 .00 Feature•: Wide bandwidth and high sensitivity. Very low power consumption. High sensitivity X-Y mode. Z axis (intensity modulation). Front panel electrical trace rotator. Regulated power supply circuit for accuracy. Deacrlption: This model is a dual trace 20MHz Oscilloscope using a high brightness CRT. The vertical amplifiers have high sensitiv~y of SmV/div and a frequency characteristic response with • s_~ t~ ~off o~ __exc~~n-~ _2~~Hz_. The hi~hest lriijgering swt,ep spe'!d:. ~ 0._2l)_S~ c/div0 Audio Oscillator & Function Generator Fantastic Hi Tech - Hi Soec <SeeEA0ec'86) Thi• ultra low dlatortlon oacllletor la comparable with the ~Ill laboratory atandard alne wave oaclllatora. Aa well•• having very low diatortion It hae excellent envelope atability, aquare wave output and output metering. SAVE PROFESSIONAL CASIO PRINTING CALCULATOR • 12 DIGITS • FULL FLOATING AND FIXED DECIMAL POINT WITH ROUND-OFF • POWERED BY 4 x AA CELLS OR M-9000 VOLTAGE ADAPTOR (NOT SUPPLIED) • NEGATIVE NUMBER HAS 00 MINUS SIGN . 5t;.\/f. S40 . X2125 $149.00 $50.00 AVIATION HEADAl>NES Normally $155 This Why pay $400 or more for a David Clark set? month only WITH OIL FILLED EAR CUSHIONS $105.00 • High performance, noise attenuating earphones. • Noise cancelling microphone • Cushioned head pad • Super sturdy • Great performance • Superb, professional pilot's headset will last a lifetime with reasonable treatment. • Includes standard aircraft jacks. FeatuNI: :~~~~:~ ::~ ~g~-~~~ ~~~r:.:;,9:,~: ~~~ \~v~J:n~•M_:::·uan~~~~~~ • Attenuator Odb-10db, • • Output wavefOfms - sine and scp.iare wave All components mount on a single PCB. Kil cornea complete with profeHional silk-screened and punch.d na~.u ■I anoci1ed alum inium front pan... K 2540 Two Brilliant New Multitesters From Altronics at Low Direct Import Prices C9070 Specifications For a 1066 / Q 1070 Engineering Multimeter Testers DC Voltage Range: 200mV, 2V, 20V, 200V, 1OOOV Accuracy: All ranges+/· 0.5% rdg + 1dgt · Input Impedance: 10Mn AC Voltage Range: 200mV, 2V, 20V, 200V, 750V Input Impedance: 10MO DC Cu11ont Range: 200uA, 2mA, 20mA, 200mA, 10A AC Cur,ent Range: 200uA, 2mA, 200mA, 10A hesistance Ra .. ge: 2000, 2kn, 20kn, 200kn, 2Mn, 20Mn, 2000Mn Capacitance Range: 2000pF, 20nF, 200nF, 2uF, 20uF TrHsistor hFE Base DC Current: 10uA, VCE: 2.8 +/- 0.4V Geoeral: Display: 3 1/2 dign liquid crystal wnh maximum reading of 1999 OVerrange Indication: Highest digit of (1) or (-1) is displayed OVER 1000 SOLDI High Energy Siren with Swivel Bracket Absolulely ear splitting SPL Q 1068 Carry Case $12.50 (suit Q 1066 & Q 1070) FREE with each multimeter ordered this month Multimeter with Temperature Meter, Capacitance, Diode and Transistor Tester Temperature Range: -2o·c to 750'C O'F to 1400'F Accuracy:+/- (3" + 1 dgt) up to 1SO'C +/- 3% rdg over 150'C +/- (15" + 2 dgts) up to 225'F Q 1066 $149.00 Logic Tester, Frequency Counter, Capacitance and Transistor Tester a 1010 $189.00 :~9J~~~~~(~~i~g7~n!~) ~.~iic 1: 2.4V Frequency~ange: 2kHz, 20kHz , 200kHz, 2MHz, 20MHz Input Sensitivity : 20MHz range 1V rms. Other ranges 35mV rms. New Super Loud 120db. Handy bracket for wall mounting etc. 12V 300mA. s 5177 $29.95 ONLY $189.00 Now available from Altronlcs Dealers Stereo Audio Mixer Amo ONLY $150.00 Allows blending of microphones, two phono inputs and either two tape or tuner inputs. • Right and left VU meters. • Fader control between phono pickups for professional cueing. • Headphone monitor • Talkover facility. Input: Mic o.smv 600 Ohms Phone 3mV 50k0hms Tape/Tuner 150mV 100k0hms Output: 250mV Frequency Response: 20Hz to 20kHz Tone Control (Treble): 10kHz (plus or minus 12dB) Tone Control (Bass): 100kHz (plus or minus 12dB Headphone lmpedance:4 ... -. . . 16 Ohms -~ PHONEORDER TOLL FREE ALTRONICS 008 999 007 • • • • • • • • • 1 I . I , • (See SC Feb'88) LARM SYSTEM This refined car burglar alarm has about every feature you could possibly want to keep would be thieves away. FEATURES: e Internal & External Sirens• Dash lamp flasher • Battery back up • Delayed & Non delayed inputs• Ignition killer• Easy to build and install. K4370 • Easy to operate Simplicity itself - just select the switch to Home, Off or Away as desired. A 45 second exiVentry delay allows you to vacate and/or re-enter your premises and disarm the system. • No key switches or code buttons to push. Thus the system is ideal for families• even the kids can operate this system. • Facility fot external siren • Battery back-up (battery B'C'cells not included) System Contents • Master Control Unit• Front Door Bell Switch • Panic/Emergency Switch • Three Window/Door Reed Switches • Mounting Hardware• 20 Metres Wire• Instruction Manual FANTASTIC VALUE Complete System S 5465 Normally $129.00 THIS MONTH ONLY $99.00 NORMALLY $129.00 THIS MONTH ONLY $119.00 Earna /ta coat hunt»rda of timN o,,., In cleaning connactora, PCB 'a, all/Ille/lea, Je-1/ery, g/euea, watchea, drafting pena, etc. Awarded the Good Product O.a/gn Award for CETDC in 1987 With Wireless Remote Control HIGH POWER CAR ALARM RADIO SAVE $10.00 Pin Point ULTRASQ NI C CLEANER WIii even clean YOU' teeth! .-:-:. . Won't saatch or damage. uses · ~ ordinary tap water and creates millicns of supcr·penetrating bubble,. Hospital tests ,how that lntruaiic cleaning produces better results safer than convcnticmal = .... BLACK II• Earth JOA/ FUSE RED method,. Pos, +Plugs into fuse box YELLOW • BLUE Door switch circuit Doors, trunk,, hood etc •. ((rm<at> Remote control 'key' This alarm system w ill be triggered by unauthorised entrance through the car doors, boot, bonnet or removal of the car sound unit. The siren w ill sound and the headlights fla~h for 60 seconds . Simple wiring, wire it yourself without professional assistance. Automatic Reset S 5220 ONLY $99 .00 High Performance - MULTI FUNCTION CAR ALARM WITH WIRELESS REMOTE \ em ('Nhere fined) . Hom Light Rashes to indicate Towing • Window f door boot or bonnet s 5225 $129.00 Direct Import Price! Passive Infra Red Movement Detector This Month Featurea: Lens simply 'snaps' to s79.oo Buy 3 for $180 ,. save $50.00 TOP VALUE NORMALLY $199.00, ONLY $174.OOTHIS MONTH A 0100 Passive Infra-Red Llte Guard Floodlight Control Fantastic value and security for only $69.00 Was $135.00 The lite Guard detects a moving person or vehicle by comparing the background temperature with a rapid change of temperature across the detection beams. So when Lite Guard detects movement across the coverage area, it will turn on the floodlight(s) for 1-20 minutes as pre-adjusted. Speclllcatton1: Detector: Dual element pyroelectric PIA sensor • Raintight outdoor all weather operation. • Photocell to deactivate sensor during daylight • Operating Voltage: 240V AC. 50Hz • Operation time: Adjustable 1-20 minutes• SeI11ltlvlty: Adjustable 20'-50' , 30 beams• Aimable desired direction with 2 ball joints • switching Capability: 500W max. incandescent.• Operation Mode1: Off, Auto. Test, Manual Ont. VERY COMPREHENSIVE rotecte from: In Just 3 minutes you wttl be amazed at the difference! Headlights either wide angle (range 40ft.) for normal use or Normal angle (ran~e 80ft plus) for corridor applications. • Snazzy integral mounting brackets allows corner 90 deg. mounting as well as normal surface mount. • "Pulse count" circuit to eliminate false triggering. • "tamper" contact. • 12V DC Powered , • Built-in test lamp• Alarm output SPOT 30V 1a. 21 st Century entertainment - fascinate your friends this Christmas! PLASMA LAMP DISPLAY Amazing! Pulsating high voltage pla1m,¾ discharge continually changes &hape and direction . Mode selectable to either fingertip control or sound activated. For example. from voice or sound system . Provides endless faseination as it sizzles and arcs. Supplied complete with AC mains adaptor . Imagine getting one for Chriatma11/ A0120Normally $199 SAVE $50.00 Up till now similar lamps have sold for $1000 and more!! THIS MONTH ONLY Get 240V AC mains power from your car battery with these hal'lfly DC to AC lnv.rter kit Nta. 12V DC to 240V AC Inverters TIii• month the relNH of our updated range of lnvertera. Bealdea technical lmprovementa. our new IMtrun.it ea- kNp theae beat aellera looking BETTER THAN EVER! PowerhouN 800W Inverter Tllla l n - r h• the capacity to produce 600 watts of mains power which will run a fantaatlc array of appllancet. Ideally aulted to running power tools, lighting (Including fluroa) electric motor, and much more. It can be uaed ea a portable or permanent fixture. • Manual or Auto Start lacilltlea • Low battery cut-out. DISCOLITE (See SIiicon Chip July/Aug '88) GrNt for partiea, allop dlaplaya and apec:lal llahtlng ellec:ta. The DISCOLITE liulln party llghta on and oll in beat with the mualc from your aound ayatam. • 4 light channela controlled by 4 aeparate audio channela • Forward, reverN & auto-reveralng cllaNr petterna • Slmultaneoua atrobe on all 4 channel• • Alternating light pattiama • Muak: modulation available on chaeer atrobe and eltemete patteme • Inbuilt microphone for beet triggering or audio modulation of llghta • Dll'Kt lnputa • Senaitlvtty control • Preaelteble aanalttvtty lew9la for Nd! Cflannel • Front panel LEDa mimic light dlaplay • Altronlca kit p,e-punched and acrNned. K 5805 $151.50 12 or 24 VOLT DC INPUT GrNt for that truck around the farm. UN with (See EA Dec '87) Beat Triggered Strobe (See AEM July 1985) Add some Ille to your next party. Designed by Australian Electronics Monthly. Flashes In time to your music plus It will work aa a normal strobe. Exclusively customised by Altronica Into our . H 0480 Instrument case, making construction a breeze and Improving 1tabilfly and overall appearance. Includes silk screened panel. •300• Watt • •Inverter • • •with• K 5790 was $79.95 NOW $70.00 SAVE $10.00 TWO TUBE OPTION FOR INCREASED POWER K 5795 $18.50 Auto Start Auto start draws power from your battery only when appliance ia plugged in and "turned on", that is battery can be left permanently connected ii required. • Voltage regulated • Current regulated • Current overload unit self limits. Complete kit K 6750 $279 Fully built and tested K 6755 $379 WANT MORE POWER FROM YOUR AMPLIFIER? LOOK AT THIS! Bridge Adaptor for Stereo Ampllflers (See EA June '85) This simple circuit makes it poaaible for any stereo amplifier to deliver lour times the single channel power into the same single load. Frequency response is 10Hz to 300kHz and harmonic distortion is leas than 0.001'!1o at 8V RMS. Gre~t for powering small appliances eg . lIghtIng , record player, CD etc. Fantastic for camping. K 6705 Value $89. K 5565 $15.95 VALUE MORE AL TRONICS DEALERS WANTED If you have a Retail Shop, you could increase your income significantly by becoming an Altronics Dealer, Phone Chris Campbell (09) 328 2199 for Details. 174 Roe St. Perth W.A. 6000 PHONE TOLL FREE 008 999 007 Perth Metro (09) 328 1599 ALL MAIL ORDERS P.O. Box 8350 Stirling Street Excl'lange Perth W.A.6000 AL TRONICS RESELLERS Chances are there 1s an Altronics Reseller right near you - check this list or phone us for details of the nearest dealer. PI••• Note: Resellers have to pay the cost of freight and insurance and therefore the prices charged by individual Dealers may vary slightly from this Catalogue - in many cases. however, Dealer prices will •till represent a significant cost saving from prices charged by Altronics Competitors. Don't forget our E1prn1 Mall and Phone Order Service- for the coat of a local call, eankcard, Visa or M•l•rcard holder• can phone order for same day d•epatch. Blue Ribbon DHlera are highlighted with a ■. These Dealers generally carry a comprehensive range of Altronic products and kits or will order any reQuired item for you. WA STANDARD DELIVERY & PACKING CHARGE $5.50 to 1Kg $8 over 1Kg AUSTRALIA WIDE - We process your order the day received and despatch via. Australia Post. Allow approx 9 days from day you post order to when you receive goods OVERNIGHT JETSERVICE Up to 3 Kg is $8.00 • 3Kg to 5Kg is $20.00- We process your order the day received and despatch via. Overnight Jelffrvlc• Courier for delivery next day Country areas please allow additional 24-48 hours. 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 11oods at consignees risk. Should you require comprehensive insurance cover against loss or damage please add 1% to order value (minimum charge $1 ). When phone ordering please request " Insurance ". TOLL FREE PHONE ORDER - Bankcard.Visa, Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight Jetaervlce we deliver next day . COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON Bird Electronics 641631 KALGOORLIE Todays Electronics ■ 212777 PORT HEADLAND Ivan Tomek Electronics 732531 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Farmer Electronic ■ 522388 DARWIN Ventronics 853622 ACT CANBERRA Bennett Commercial Electronics 805359 VICTORIA CITY All Electronic Components 6623506 The Electronic Component Shop ■ 6706474 SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston Electronics ■ 4840191 COUNTRY BENDIGO KC Johnson ■ 411411 SHEPPARTON Tattersal Sounds 8212892 MILDURA McWilliam Electronics 236410 WARRNAMBAL Kovoit Electronics 627417QUEENSLAND CITY Delsound P/ L 8396155 SUBURBAN CAPALABAKingsway Electronics 3902399 WOODRIDGE David Hall Electron,cs 8082777 COUNTRY BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronics 724459 MACKAY Phiitronics ■ 578855 ROCKHAMPTONAccess Electronics (East St.) 221058 TOOWDOMBA Hunts Electronics ■ 329677 TOWNSVILLE Solex ■ 7724466 MAROOCHYDOREMals Electronics 436119 SA CITY Force Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIES BEACH Force Electronics ■ 3823366 ENFIELD Force Electronics ■ 3496340 FINDON For.ce Electronics ■ 3471188 LONSDALE Force Electronics ■ 3260!101 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Electronics ■ 454764 TASMANIA HOBART George Harvey ■ 342233 LAUNCESTON George Harvey ■ 316533 NSW CITY David Reid Electronics ■ 267 1385 CITY SOUTH Sheridan Electronics 281 7727 CARINGHAH Hicom Unitronics 524 7878 BLACKTOWN Sheridan Electronics 621 1494 COUNTRY COFFS HARBOUR Cofls Harbour Electronics 525684 GOSFORD Tomorrows Electronics 247246 GRAFTON East Coast Electronic 431250 NEWCASTLE Novocastrian Elect. Supplies 621358 RAYMOND TERRACE Alback Electronics 873419 WINDSOR 11, ·, E Electronics 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 WAGGA WAGGA Philli s Electronics 216558 ·. FAST CHARGER NICAD BATTER! This Nicad Fast Charger is designed to operate from a 12V car battery. It can charge nicad battery packs from 6-12V at currents up to 6A, or you can wire the circuit to charge battery packs up to 30V at reduced current. and that ultimately leads to cell damage and loss of performance. According to the battery manufacturers, the correct way to recharge a nicad battery pack is to first discharge each cell in the pack to its end point (about 1. 1V) and then recharge it at the 10-hour rate for 14 hours. Clear as mud? OK, let's say that we have a battery pack rated at 1300mAh. This should ideally be recharged at a 130mA rate for 14 hours. So why fast charge nicad batteries? Well, there are many situations where you may want to recharge a nicad pack quickly, particularly if you are involved with radio controlled models. For these applications, the bat- Nicad battery packs are expensive but many people risk damaging them by using primitive fast charging techniques. At its crudest, a fast charger consists simply of a pair ofresistive leads connected to a car battery. The idea behind the resistive leads is to limit the charging current into the battery but that doesn't stop overcharging if you don't constantly monitor the battery and disconnect the leads at the correct time. The same goes for many commercial fast chargers on the market. Often, there is no automatic shut-off feature or the shut-off feature is unreliable. Instead, the charger just carries on pumping current into the cells FUSE +12V PUSH-PULL OUTPUT VOLTAGE CONVERTER STOP FIXED VOLTAGE DROP NICAO BATTERY FEEDBACK CURRENT SENSING RESISTOR 8-BITUPONLY ANALOG TO DIGITAL CONVERTER Fig.1: basic configuration of the Nicad Fast Charger. Power for the circuit comes from a 12V battery & this drives a DC-DC converter which charges the battery pack. The analog-to-digital converter, together with comparator IC8b, functions as a peak detector & shuts down the converter at the end of the charging period. 32 SILICON CHIP tery packs can handle considerably higher charge (and discharge) currents than ordinary nicad cells. Of course, the risks of overcharging and irreversible cell damage are much greater if fast charging is employed. And that's where this project comes in. It detects when the battery is fully charged and automatically switches the unit off to prevent overcharging. Unlike previous designs (eg, our Megafast Nicad Charger in June 1988), this charger uses digital circuitry to detect when the battery is fully charged. This ensures more reliable operation than analog detection techniques - in fact, it's virtually foolproof. In operation, the circuit will recharge a typical nicad racing pack in about 20 minutes. Large battery packs There are several other features which make this charger an attractive unit. First, it can be switched in five 1.2V steps so that it can fast-charge any nicad battery pack from 6-12V at 6A (ie, 6V, 7.2V, 8.4V, 9.6V & 12V). The 6th switch position is labelled "Custom" and that's the position you select if you want to recharge a battery pack to greater than 12V (up to about 30V). It's this ability to recharge large numbers of series-connected cells to voltages greater than 12V that really gives this unit the edge over previous designs. For example, you may be involved with electric flight models and need to recharge a string of 24 cells to 28.8V. To do this however, you have to change the number of turns on the secondary of a transformer during construction from the value normally recommended. In this case, the lower ranges will still work The Nicad Fast Charger is built into a standard plastic instrument case. It can charge nicad battery packs from 6-12V at 6A or you can wire the circuit to charge a custom battery pack (eg, 24 cells in series) at reduced current. but the current capability will be greatly reduced. We'll say more about this in Pt.2 next month. The Nicad Fast Charger is also more efficient than other fast charger designs we have seen. That translates into more charges from the car battery. It also features reverse polarity protection and there is provision for trickle charging as well as fast charging. In addition, the circuit features a low-voltage cutout feature to prev:ent you from flattening your car's battery - the usual source for most radio control modellers. Note, however, that the circuit does not feature automatic shut-off in the trickle charge mode. That feature is reserved for the fast-charge mode only where it is much easier to detect the fully-charged condition. Charge status Three LEDs on the front panel indicate the operating status of the charger. When the Start button is pressed, the Charging LED comes on and remains on until the batteries are fully charged. At this point, the Charging LED goes out and the End Of Charge LED turns on. ·' The third LED is the Error indicator. It lights if the wrong charging voltage is selected for the battery connected. In practice, the unit is very easy to use. You simply connect the battery, select the appropriate voltage and press the Start switch. After that, it's just a matter of waiting until the End Of Charge indicator comes on. Block diagram Now take a look at the block diagram of Fig.1. This shows the basic configuration of the Nicad Fast Charger. Power for the circuit comes from the 12V car battery. This drives a DCDC converter circuit, the output voltage of which is controlled by the current through a current sensing resis- tor in series with the nicad battery pack. In operation, the output voltage of the converter automatically adjusts to maintain a constant voltage across the resistor and thus a constant current through the nicad battery. For example, if the nicad battery is almost completely flat, then the output voltage of the converter automatically adjusts to maintain the correct current. The advantage of this scheme is that the power dissipation of the circuit is low, with losses occuring only in the push-pull converter driver stages and across the current sensing resistor. The ability of the converter to produce an output greater than 12V also makes it possible to charge nicad battery packs to voltages greater than the 12V produced by the battery. The remaining circuitry is used to monitor the charge on the nicad battery and shut the charger down when the battery is fully charged. The full charge condition is detected by the small drop in battery voltage that JANUARY 1991 33 ;- 1.8 1.7 ~ 1.6 ~=.... g 1.5 1.4 1.3 0 ~ / IC4 ---G CLK MSB OUT BINARY COUNTER IC 5 R LSB RESET INPUT 07 06 05 04 03 02 01 00 / I 8-BIT I DIGITAL I OUTPUT I 81 82 83 84 85 86 87 88 REFERENCE DAC IC6 10 15 20 CHARGE TIME (MINUTES) Fig.2: typical charging curve for a single cell in a 7.2V 1300mAh racing pack. Note how the voltage falls at the .end of the charging cycle. This voltage drop is detected by the AID converter, which then shuts the circuit down to prevent overcharging. occurs as the battery heats up under overcharge conditions - see Fig.2. ·It works like this. First, the battery voltage is dropped by a fixed value and then applied to the inverting input of a comparator (IC8b) and also to an up-only 8-bit analog-to-digital (AID) converter. The output of the AID converter then drives the non-inverting input of the comparator. Thus, IC8b compares the analog input and output voltages of the AID converter. Normally, the output of IC8b is low but if the battery voltage falls, the voltage on the inverting input ofIC8b will fall below the voltage on the non-inverting input (since the AID converter can only count up to a peak). The output of IC8b will thus switch high to shut down the pushpull converter circuit and end battery charging. Fig. 3 shows the basic arrangement of the up-only AID converter. It consists of comparator IC8a, a gated clock (IC4), and a binary counter (IC5) with its 8-bit output connected to the 8-bit input of a digital-to-analog converter DAC (IC6). This produces an analog output which corresponds to the count provided by the binary counter. Thus, when the binary counter has a count of 00000000, the analog output will be at 0V. Conversely, when the counter has a count of 11111111, the analog output will be at its maximum - say 5V. For the remaining 254 counts in between these two extremes, the analog output is incremented by 34 BATTERY SAMPLE I ~ GATED CLOCK COMPARATOR SILICON CHIP Fig.3: block diagram of the up-only AID converter. When the output ofIC8a is high, IC4 clocks binary counter IC5. This counter then drives digital-to-analog converter IC6 and this produces an analog output which corresponds to the count in the binary counter. As soon as the sampled battery voltage drops below the DAC output, IC8a's output goes low & stops the clock, thus freezing the DAC output at its peak. about 20mV for each count. Because of the very small increment between each count, it is necessary to include a reference voltage for the DAC so that the analog output is repeatable and accurate. The analog output from the DAC is fed to the inverting input of comparator IC8a where it is compared with a sample of the battery voltage on the non-inverting input. This comparator controls a clock circuit. When the DAC output is lower than the battery voltage, the comparator output is high and so the clock signal is applied to the binary counter. This in turn increments the binary counter and so the analog output voltage from the DAC rises. When this voltage just exceeds the sampled battery voltage, IC8a's output switches low and stops the clock. Thus, the DAC analog output voltage is held (or frozen) at its peak. Fig.4 shows the waveforms involved in this operation. Note that the steps shown for the DAC output are not to scale, since in reality, they only increment in 20mV steps. When first powered up, the DAC output is at 0V because the binary counter (IC5) is initially reset. Thus, the comparator output is initially high, the clock is enabled and the DAC output steadily increases until it just exceeds the sampled battery voltage. The comparator output then goes low, the clGJck stops and the DAG output remains steady. If the battery voltage later rises again due to charging, the comparator again switches high and restarts the clock to increment the DAC output voltage. However, when the battery voltage subsequently falls (ie, when it is being overcharged), the DAC output remains as it is since the comparator output stays low. Thus, the DAC is a peak hold circuit which registers the peak battery voltage and holds it until the counter is reset. Circuit details Fig.5 shows the final circuit of the Nicad Fast Charger. Despite the apparent complexity, it's really quite straightforward. In fact, you should be able to identify most of the circuit COMPARATOR OUTPUT CLOCK OUTPUT ANALOG VOLTAGE (DOTTED) _____ ~---_,,.,. ✓--, ' ..... __ _ Fi'g.4: these waveforms show how the DAC output increases until it just exceeds the sampled battery voltage during charging. Notice how the comparator output again switches high & enables the clock when the battery voltage later rises due to charging. The DAC output then rises until it again exceeds this new level. functions by comparing it with Fig.1 and Fig.3. The push-pull converter circuit is right at the top of Fig.5 and includes ICl (TL494), Mosfet transistors Q1Q4, transformer Tl, and rectifier diodes D4 and D5. ICl is really at the heart of the converter circuit. This is a dedicated switchmode IC from Texas Instruments and it includes all the necessary circuitry for generating complementary square wave pulses at its pin 9 & 10 outputs. These outputs are pulse width modulated by internal error amplifiers to regulate the output voltage of the converter. The inputs to the internal error amplifiers are at pins 1 & 2 (+Cl & -Cl) for one amplifier, and at pins 16 & 15 (+CZ & -C2) for the other. In addition, the IC contains an internal sawtooth oscillator, a 5V reference (pin 14) and a "dead time" control comparator. The latter is included to prevent the push-pull outputs at pins 9 & 10 from rising and falling at exactly the same time. The dead time input is at pin 4 and is tied to the 5V reference at pin 14 via a 4. 7µF capacitor. When the dead time input is at the reference voltage (5V), the output transistors are off and as this voltage drops to ground, the dead time decreases to a minimum. In this circuit, the dead time control is used to provide a soft start. When power is first applied, the 4.7µF capacitor pulls the dead time input (pin 4) to +5V and thus prevents the output transistors inside ICl from switching on. The 4. 7µF capacitor then charges via the 4 7kQ resistor on pin 4 and as it does so, the duty cycle of the output transistors gradually increases until full control is gained by the error amplifiers. Error amplifiers Now let's look at the role of the two error amplifiers. The first error amplifier, with inputs at pins 1 & 2, is primarily used to shut down the converter when the nicad battery is fully charged. Its noninverting input (pin 1) is connected to the +5V reference while the inverting input (pin 2) is connected to a control line which, in turn, is controlled by comparator IC8lr. When this control line is above +5V, the converter functions normally. However, when the line drops below PARTS LIST 1 Plastic instrument case, 259 x 190 x 82mm 1 PC board, code SC14101911, 167 x 222mm 1 Dynamark front panel label, 249 x 75mm 1 metal rear panel, 249 x 76 x 1.5mm 1 finned heatsink, 110 x 74 x 33mm 1 Neosid 17/742/10 iron powder ring core 1 Siemens EC-41 N27 ferrite transformer kit 1 panel mount 3AG fuse holder 1 10A 3AG fuse 2 cordgrip grommets 1 SPOT miniature momentary pushbutton switch (S1) 1 2-pole 6-way rotary switch (S2) 1 DPDT miniature toggle switch (S3) 4 5mm red LEDs (LED1-LED4) 3 5mm LED bezels 5 T0-220 insulating mounting kits 6 10mm-long screws and nuts to suit insulating bushes 26 PC stakes 2 battery clamps to suit 12V battery 1 polarised socket (to suit nicad battery pack) 1 1-metre length twin of automotive wire (1 0A or greater) 1 3.5-metre length of 1.25mm enamelled copper wire 1 450mm-length of 0.8mm tinned copper wire 1 1.5-metre length of light-duty hookup wire 4 self-tapping screws 4 rubber feet 2 10kQ miniature horizontal trimpots Semiconductors 1 TL494 switchmode IC (IC1) 1 4050 hex buffer (IC2) 1 LM833 dual op amp (IC3) 1 555 timer (IC4) 1 4020 binary counter (IC5) 1 DAC0800 DIA converter (IC6) +5V, the output of the error amplifier switches high and reduces the pulse width to zero, thus effectively shutting the converter down to end battery charging. A secondary function of this control line is to shut down the converter 1 TL072 dual op amp (IC?) 1 LM393 dual comparator (IC8) 4 BUZ71, MTP3055 Mosfets (Q1-Q4) 2 BC337 NPN transistors (Q5,Q6) 1 BYX98 10A stud mount diode (D1) 21N40021A diodes (D2,D3) 2 BYW29, MBR1645 16A Schottky diodes (D4,D5) 1 15V 5W zener diode (ZD1) 2 30V 1W zener diodes (ZD2,ZD3) 1 3.3V 400mW zener diode (ZD4) 2 5.6V 400mW zener diodes (ZD5,ZD8) 1 9V 400mW zener diode (ZD6) 1 zener diode (ZD7 - see text) 1 LM336-2.5V reference diode (REF1) 1 MCR100-6 SCR (SCR1) Capacitors 1 2200µF 50VW PC electrolytic 1 2200µF 16VW PC electrolytic 1 47µF 16VW PC electrolytic 5 10µF 16VW PC electrolytic 5 4. 7µF 16VW PC electroly1ic 1 2.2µF 16VW PC electroly1ic 2 1µF 16VW PC electroly1ic 1 0.47µF 16VW PC electrolytic 2 0.1 µF monolithic 1 0.1 µF metallised polyester 3 .022µF metallised polyester 1 .01 µF metallised polyester 1 .001 µF metallised polyester Resistors (0.25W, 5%) 1 2.2MQ 2 4.7kQ 1 470kQ 2 4.7kQ 1% 2 220kQ 5 3.3kQ 5 100kQ 1 1.5kQ 2 47kQ 31kQ 1 33kQ 1 820Q 1 22kQ 1% 1 680Q 0.5W 1 20kQ 1% 2 47Q 1 15kQ 410Q 12 10kQ 1 1Q 1W 1 6.8kQ 2 0.22Q 5W WW Miscellaneous Solder, heatsink compound. if the voltage on the 12V car battery drops below a preset level. This is achieved by connecting the control line to the +12V supply via a voltage divider consisting of a lkQ resistor and an 820Q resistor. Thus, if the battery voltage drops below 11 V, the JANUARY 1991 35 junction of the voltage divider drops below 5V and the error amplifier turns off ICl. The second error amplifier, with inputs at pins 15 & 16, is used to regulate the output voltage of the converter. In operation, the voltage across the current sensing resistor (2 x 0.22Q 5W resistors in parallel) is fed to the non-inverting input at pin 16 and compared with a sample of the +5V reference on the inverting input at pin 15. Thus, if the current through the 0.22Q resistors (and thus through the nicad battery) rises above a preset value, the output of the error amplifier also rises and this reduces the width of the pulses from ICl to bring the current back down again. Conversely, if the current falls below the desired value, the error amplifier output also falls and the pulse width increases. The gain of this error amplifier is set by the 4 70kQ feedback resistor between pins 3 and 15. Trimpots VRl & VR2 are used to set the voltage on the inverting input (pin 15) , with S3a used to select either trimpot wiper to provide fast or trickle charging. The complementary PWM outputs from ICl appear at pins 9 & 10 (El & E2) and are switched at a rate of about 20kHz. This frequency is determined by the 33kQ resistor and .00lµF ea~ pacitor on pins 5 & 6, which set the frequency of the internal oscillator to about 40kHz. Actually, El & E2 are the uncommitted emitter outputs of complementary switching transistors inside ICl. These emitters drive paralleled buffer stages IC2a, IC2b & IC2c on one phase of the output waveform and IC2d, IC2e & IC2f on the other. Their outputs then drive Mosfet transistors Ql , Q2 , Q3 & Q4 which in turn switch the 1;:; ".i"' SILICON CHIP . > ~;;: ;!: f-i•· ,-.;;: "' > I c::,C> "'"' N ... "'C'? ~ ;;: .,;1; "'+ ~ + ci~ I• ~ 1(fj C, C, o.i ,------1 --- - - -~+~ --.;1 .. "' ~~ ICw ""'-' '-' :c I• I• ~ I• "'"' H•· ~ =... t; C, ~ ~ C, C, N '-' IC -:;j + c = /;:; !iil .... "' . "'- 8 - 36 ~ C, C ;:; "' N \!! I -= ... ~ c N '-' =-'-' I· =!~ > Fig.5 (right): the final circuit uses ICl which is a dedicated sw itchmode device to drive Mosfet transistors Q1Q4 in push-pull mode. These then drive step-up transformer Tl, the output of which is rectified to produce a DC voltage to charge the battery. IC8a, IC4, IC5, IC6 & IC7 form the AID converter shown in Fig.3. As soon as the sampled battery voltage falls by 80m V from its peak, the output of IC8b switches high & turns on SCR1 to shut down the converter circuit (ICl, Q1-Q4 & Tl). ~ > u. w IC > ;!"' ;:; - '-' I + C, !;; \:? + f-1•· .... ., ~ >"f ~ ,-.;;: ~t; ..... ... ~ ~~ :cZ ~~~i~ ::, E '-' I· ~ 1;:; ► w::, IC>- '+ I="~!,; o-1•· i\; C, "'"' ~t;jN.:.: ICc, U ...cccn>- 'I t,.;I ..... co co ..... -<: ::0 §: >' :z: Jt 16VW+ 1 10k 22k -1%, .,. 10 Jt 16VWJ ~i~C8f • UNDER <+5V CHARGE OFF >+5V NORMAL CHARGE .022 1% 20k +9.3V .>' +5V 220k 10k +9.5V 8200.,. # +9.55V REF +12V .,. t t ~, 1 \)I ; t 1 .i.: 16VW.:r: 08 1N4148 .,. 10k 1.5k S3b 10k r--------+12V I 0.1! .,. +5V REF +12V VOLTAGE DROP DETECT ., .,. 0 LM336 KGA - +A VIEWED FROM BELOW 0 C103 ~K OAC OUT 0 ,; EOC 8 4.7 .J.: 16VWJ .022! 100k 100k +5V 4.7k 1% CLOCK IC4 555 IC5 4020 4.7k D12 011 VLC 1 r .,. .01I COMP $ V· m 5 ~ 1 1a 19 110 111 1~ 81 82 83 84 85 86 87 88 - VREF+ IC6 glO OAC0800 2IIO lLRfF• 15 1- file I 13 10 .i,,: 16VW! +12V -, vwI 10 ~ 15 f .- +5V 101 +1iv 16VW"I"!. COUNTER 011010 09 08 07 06 05 04 5 14 12 13 6 4 5 7 10•cK ~6 NiCad FAST CHARGER 4.7k +5V +9.5V 4.7k 1% 010 1N4148 10 _.:16VWJ ,----+---------------------•12V ERROR CLOCK STOP 6.8k 10k 06 BC337 ~ .~ AGK 0 MCR100 15k 4.7. 16VW+ BATTERY_V_OLTAGE I 11,:11,,,;:;, \ \ 1>,ri,?11/iI ' ... . _, .,, '1::;;, '""~ TY N E DRIVES!! 5 'I•" 360K DRIVE • 500K unl ormatted • IBM ' compa1,b1e xr Cat.Cl 1901 $175 51/4" 1.2 M/BYTE COPAL DRIVE . "'(,,, 20 MEG HARD DISK WITHOUT CONTROLLER .............. $399 20 MEG HARD DISK WITH CONTROLLER ............. ,499 tUl&I #ri: t·i ;I •l•l l#J: 28ms ACCESS WITH IDE/FDD CONTROLLER ............ $495 80 MEG HARD DISK 28 ms ACCESS WITH IDE/FDD CONTROLLER .......... $895 • 1.6 M/Byte unformatted • IBM• AT• conpa!ible OKI LASER PRINTER Introducing the new gen~ration !n page printers, the OKILASER 400. The affordable LED page printer designed for the small business. Rel!able and compact, the OKILASER 400 flts neatly Into the smallest of offices. Highly rel!able due to the latest LED Imaging technology, the OK!LASER 400 offers excellent print qual!ty, superior paper- handl!ng, and a variety of fonts wh!ch rival some of the more expensive laser printers on the market_ • Printer speed : 4 pages/minute • Data Buffer : S 12K Byte • Resolution : 300 x 300 DP! 1 M/byte expansion (option) • Resident fonts : 25 2 M/byte expansion (option) • Emulation : HP Laser Jet Serles II Max 2.5 M/byte C22061 .-----------·····················"···············"···· $1675 lJ 3'12" 1•44 MiBYTE DRIVE • Sw1l chable 1 44 MIBytc 1ormatted or 720K formatted • Double sided. double dens11y • P6wer supply adaptor provided • 5 11,1 " mounted Cat. Cl 1911 ...... ... $195 CONTROLLER CARD TO SUIT X18009 $139 FREE CATALOGUE WITHEVERY MAIL ORDER• BACK BY DEMAND! TOWER COMPUTER CASES Remount your computer to give It that professional look! Accepts XT, AT, Baby AT, & 386 boards. Horizontal full height hard disk drive mounting. X11105 ...................................... $249 Power supplle to suit X11102 ......................................$225 IC8b, even if the nicad battery pack is completely short circuit. The output of the fixed voltage drop selected by S2 represents the battery voltage and is applied to pin 3 of comparator stage IC8a. Its pin 1 output controls the reset input (pin 4) of 555 timer IC4 which is wired as an astable oscillator with a frequency of about 100Hz. This frequency is set by the two associated lO0kQ resistors and the .022µF capacitor on pins 6 & 2. The finned heatsink is fastened to the rear panel via the mounting screws used to secure the four Mosfet transistors. Its job is to substantially increase heat dissipation & thus keep the Mosfet transistors cool. primary of transformer Tl. Thus, when pin 10 of IC1 goes high, Ql & Q2 turn on and switch the Sl terminal of the transformer primary to ground. When pin 10 goes low again, these transistors switch off and Q3 & Q4 switch on and drive the other half of the primary. The lOQ resistors in the gates of the Mosfets are there to ensure that the paralleled Mosfet pairs share the current equally, while DZ, ZD2, D3 & ZD3 protect the Mosfets by suppressing spikes generated by the transformer. In summary then, the power Mosfets in each phase of the circuit alternately switch the Sl & F2 terminals of a centre-tapped transformer primary to ground, so that the transformer is driven in push-pull mode. The resultant AC waveform is then stepped up by the secondary of the transformer and rectified using Schottky diodes D4 & D5 . Inductors 11 & 12 and the associated 2200µF capacitor filter the diode outputs and the resultant DC output is then applied to the nicad battery. This battery (which may consist of many individual cells) is connected across the converter output in series with the parallel 0.22Q current sensing resistors. Thus, the voltage developed across the 0.22Q resistors depends on the current through the nicad battery. This voltage is filtered using a 10kQ resis40 SILICON CHIP tor and 0. lµF capacitor and fed back to one of the error amplifiers to regulate the converter output, as described previously. In addition to the nicad battery pack, the converter output also drives the Charge LED (LED 1) via S2, a fixed voltage drop , a 680Q resistor and transistor Q5. During charging, SCR1 is off and Q5 is turned on via the lkQ resistor connected between Sl and the anode of SCRl. Thus, when Q5 is on, LED 1 lights to indicate that charging is in progress. Fixed voltage drop Switch S2 selects the fixed voltage drop and this in turn sets the charging voltage to suit the nicad battery pack. In position 1, the voltage drop is provided solely by the lO0kQ resistor on the anode of D6. This is the 6V range for charging a 6V battery pack or five 1.2V cells in series. The remaining switch positions select LED4-ZD7 for the 7.2V, 8.4V, 9.6V, 12V and custom ranges respectively. These selected voltage drops are there simply to reduce the voltage applied to the inverting input of comparator IC8b, since the DAC tracking circuitry can only operate from a range of 5 to 9.5V. Because of this limited operating range, D6 and its associated components are included to ensure that there is always at least 5.6V on pin 6 of Normally, the output of IC8a is high and so IC4 is enabled and it clocks binary counter IC5 via diode DlO. DlO and the associated lOkQ pullup resistor ensure that this clock signal swings only between +5V and+ 12V to match the supply rails to IC5. In order to operate correctly, the DAC requires a reference voltage to provide a fixed current via the 1 % 4.7kQ resistor to its VREF+ (pin 14) input. The 9.55V reference used is derived from the +5V reference of IC1 via op amp IC3b which has a gain of 1.91. In addition, the +5V reference from IC1 is buffered using unity gain non-inverting stage IC3a to provide a +5V supply rail for IC5 & IC6. IC7a (TL072) converts the output current from pin 4 of IC6 to a voltage output and applies this to the inverting (pin 2) input of IC8a. The 1 % 4.7kQ feedback resistor across IC7a ensures that its output voltage is within the 5V to 9.55V range. As soon as the DAC output exceeds the sampled battery voltage, IC8a switches its pin 1 output low and stops the clock (IC4). This freezes the binary counter and thus also freezes the DAC at its peak count as described previously. However, if the battery voltage subsequently rises again (ie, as charging proceeds), IC8a will again switch its output high and the DAC output (pin 1, IC7a) will again increase to slightly greater than the battery voltage before freezing at this new level. End-of-charge detection In addition to driving ICBa, the output of IC7a is also reduced by 80mV and applied to the pin 5 input of IC8b. This 80mV reduction in level is derived by using IC7a to drive a voltage divider network (3.3kQ & 100kQ) which is connected in parallel with a 2.5V reference diode (REF1). The resulting 80mV-reduced signal is A single large PC board makes it easy to build this project, despite the circuit complexity. There are just two trimpot adjustments to make when the assembly is completed: the fast & trickle charge rates. then derived from the tap of the voltage divider and applied directly to IC8b where it is compared with the sampled battery voltage. As stated earlier, when the nicad battery is fully charged, further charging results in a slight reduction in output voltage (see Figs.2 & 4). So, as soon as the nicad battery voltage falls by 80mV from its peak value, pin 7 of IC8b goes high and turns on SCRl via D9 and a 3.3kQ resistor. This then pulls the control line to pin 2 of ICl to about 3.4V (1V across the SCR + 1.8V across LED 2 + 0.6V across D7) and so the converter shuts down and battery charging ceases. Because it is now forward biased, LED 2 lights to indicate the end of charge condition. At the same time, the SCR pulls the base of Q5 low and this turns off to extinguish charge indicator LED 1. Once triggered, the SCR can only be switched off by reducing the curr!;lnt through it to zero. This task is performed by Reset (Start) switch Sl which also resets binary counter IC5, by pulling its reset pin to +lZV. S3b disables the AID converter circuitry by holding the reset line to IC5 high, when the trickle charge mode is selected. This means that the batteries are left on charge when trickle charge is selected. There is no automatic shutdown for this mode. This is not a problem though because trickle charging is not likely to cause cell damage. Error detector Comparator IC7b provides an error warning if SZ is set to a range that is too low to suit the battery on charge. When this happens, IC7a's output will eventually rise above 9.3V and this triggers IC7b which switches its output high. This triggers SCRl via ZDB & DB to shut down the charger and at the same time lights the error LED (LED 3). Note that ZD8 is necessary because IC7b's output does not go fully .to ground since it is an bp amp rather than a comparator. Without the zener diode, the SCR would be triggered by IC7b as soon as power was applied to the circuit. The output ofIC7b also drives transistor Q6 via ZD8 and a 15kQ resistor. When IC7b's output switches high, Q6 turns on and pulls pin 4 of IC4 low to prevent further clocking of IC5. What about the reverse situation, where the range selected is too high for the battery being charged? In this situation, the battery will never fully charge and LED 1 (Charge) will usually remain off or be very dim. That's all we have room for this month. Next month, we will give the full construction details. SC JANUARY 1991 41 VINTAGE RADIO By JOHN HILL My fancy European models All the radios in my collection were Australian made until a few months ago when, suddenly, two additions changed all that. It happened when a friendly retired farmer knocked at my door. Don had heard that I collected radios and, as he was selling up and moving into town, it seemed that he would have no further use or room for his valve receivers. He thought I might like to buy them. Being interested in any valve radio, I went out to his utility to inspect the sets he had to offer. I found myselflooking at two of the most impressive receivers I had ever seen. One was a dual-wave, 5-valve, Dutch Philips receiver with tuning indicator and twin speakers; the other a German Nordmende receiver. The Nordmende is a large table model; correction, a very large and heavy table model. It is multi-band and covers all the frequencies one would expect of such a receiver. However, the big bonus with this set is the fact that it has an FM band as well. Not only is it capable of tuning in FM stations, but it does so in stereo as well. A valve count reveals that the Nordmende has 11 valves plus a tuning indicator. As six of the valves are twin types the set has, in reality, 17 valve functions. The Nordmende receiver is a large & impressive table model. It has four loudspeakers and two push-pull channels for stereo FM or for an external stereo turntable. 42 SILICON CHIP Each channel has an ELLB0 (twin power pentode) in the output stage which drives two speakers in pushpull. The set has four speakers in all. Although I have no specifications on the set, eight watts per channel seems a realistic figure. The Nordmende is quite a radio! When I first saw these sets in the back of the ute I was impressed, but deep down inside I thought that they would be too expensive to buy. However, the prices were not as bad as I thought they would be and when I was told "$10 for the small one and $40 for the big one", it seemed to be a reasonable price. I hoped Don wouldn't change his mind while I fumbled for my wallet. $50 for two imported receivers in excellent condition and working order was a good buy. Both sets have an up-market look about them that makes them quite desirable from a collector's point of view. Of the two, the Nordmende is the more outstanding. Apart from the FM stereo aspect, it also has other features that seem to be typically European. The large full-width dial is one such feature. All the major stations are marked with the name of the city from which they broadcast. Place names such as Frankfurt, Budapest, Berlin, Brussles, Belgrade, and many others cover the dial. There is little doubt as to the market for which the set was made. At the push of a button, one can change from the receiver's internal aerial to an external aerial if so desired. The built-in aerial is a ferite rod which can be rotated through nearly 360 by turning a control knob on the front panel. There is also a visual indicator to show the rotary aerial's position. This feature seems Service Tips This imported Dutch Philips set is an up-market 5-valve receiver. It has separate bass & treble controls, three shortwave bands and a tuning indicator. This additional European-made Philips receiver was acquired from a country junk shop. When fully restored, it will make a very worthwhile addition to the author's collection. to be fairly common on the better class of European receivers. The aerial for the FM tuner is also built into the set and takes the form of a foil ribbon attached to the inside of the cabinet. A directional aerial for FM reception would have been a good idea but has not been incorporated into the design. There is a socket for an external aerial if required. Pushbutton switches An_other feature is the set's pushbutton switches. All wave-change and on/off functions are carried out by a block of pushbutton switches at the front of the receiver. While these switches are working at the moment, the mind boggles at the thought of what might happen when they wear and do not switch in and out properly. Tone control on the Nordmende is better than average. There are two controls; one for bass, the other for treble. Very few radios have separate bass and treble controls. It also has provision for a pickup, which means Instability Problems · Most cases of instability (hollow sounding reception and/or whistles when tuning across a station) can be traced to faulty electrolytic filter capacitors. Another cause can be poorly earthed · or missing valve shields, particularly around the IF valve. Always suspect Philips "metallised" valves - these were sprayed with a gold or red metallic paint which was earthed via a thin wire around the valve at the bottom of the painted section (just above the bakelite base). This wire went down into the socket and connected to a valve base pin which was earthed. The red valves, such as ECH33, ECH35 & EBF35, frequently have paint which is cracked & flaking. Bases can also become loose. Repairs can be attempted with Araldite® & by hand painting with a metallic conductive paint. If problems persist or if the old paint has flaked badly, replace the valve or fit a shield. Alignment of Early Receivers Many early superhets are aligned using trimmer capacitors accessed through holes in the top or (less frequently) bottom of the IF cans. The trimmer across the primary often has full high tension voltage on the adjusting screw and this is easily shorted to the can by a metallic screwdriver blade. Use a sharpened knitting needle as an alignment tool. It will also eliminate any detuning which can be caused by a metallic blade. that records and tapes can be reproduced in stereo if required. It is fairly obvious that the Nordmende, with its two (stereo) channels, is- a fairly late model valve radio. Although old valve receivers are generally considered more collectable than modern ones, I do not believe this to be the case with my twinchannel German model. I consider it to be very collectable because of its rarity. The 5-valve Dutch Philips is also from the tail end of the valve era and JANUARY 1991 43 Pushbutton switching was popular in Europe at the time the Philips & Nordmende receivers were made. It works well but could be troublesome to repair if anything goes wrong. good secondhand replacement soon solved that problem. A good point with both of these imported radios is that they are built with quality components. There are no horrible paper capacitors, as in older sets, which frequently break down and give trouble. The sets needed very little work done on them apart from a good clean up. In keeping with many other European sets, both receivers can be plugged into a wide range of power supplies. A rotary -switch selects one of a number of power transformer taps from 90V to 220V. The 220V tapping worries me a little, for the reason that the local supply is around 250V. As a result, everything lights up fairly brightly. Hopefully there is sufficient tolerance in the design to accommodate the difference. Another Philips it looks a very modern radio. This is in spite of the fact that it has a timber cabinet; something we have come to expect with older models, rather than with modern sets. Its shape is long and narrow, with a 7 x 5-inch oval speaker housed behind a plastic grill at each end. The cabinet stands on short legs and the overall effect is quite stylish. The dial has only the appropriate frequencies for the broadcast and three shortwave bands. The large dial glass occupies almost the entire front of the set. Like the Nordmende, the Philips receiver has separate bass and treble controls. These two radios are the only ones in my collection that have this refinement. Pushbutton switches must have been the in thing in Europe at the time, and the Dutch seemed to have been just as keen as the Germans to use them. A cluster of switches at the front of the receiver controls the on/ off and band-switching functions. Removing the chassis revealed that the receiver is a fairly standard five valver. The valve complement is: ECH81, EF89, 6BD7, 6BQ5 and 6V4. The tuning indicator is a type EM84 and is situated at the left hand side of the control panel. This indicator was not working when the set was bought but what can you expect for $10! A This close-up view shows the righthand control knobs on the Nordmende. The inner knob is for tuning, while the outer knob rotates the internal aerial. The rotary aerial position indicator is above left of the control knobs while the tuning indicator is to the right. 44 SILICON CHIP My wife keeps telling me that things always happen in threes and this time, she was right. Personally, I consider such happenings to be coincidental. Nevertheless, while browsing through a country junk shop, there it was - another Dutch Philips receiver. Once again it was a large table model, only this one was in Bakelite, or so I thought at the time. Removing some of the grime revealed a dark brown plastic - definitely not Bakelite! Anyway, I can't complain too much. $25 for a 6-valve receiver, with a tuning indicator and in working order, wasn't an unreasonable price to pay, even if it was a bit shabby. This second Philips receiver has These are the lefthand control knobs on the Nordmende. The large inner knob is for volume while the outer knob is the stereo balance control. The two smaller knobs to the left are the bass & treble controls. Resurrection Radio Vin N1 eless Specialists Repairs r tion 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. Many European sets have odd (by Australian standards) valves in them. The ECC808 valve is just one example and those shown here had to be imported at considerable expense. many of the previously mentioned features of the other two European sets: separate bass and treble controls, pushbutton switching for on/off and shortwave bands, and an inbuilt ro, tating ferrite rod aerial. But unlike the Nordmende receiver, there is no FM - stereo or otherwise. At the time of writing, this receiver has not been restored and is currently waiting its turn. Parts are available for the enthusiasts 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 catalogue. WA TED pur 1 Rad o , etc. u CASrl Call in to our Showroom at: 51 Chapel Street, Windsor,Vic 3181 PO Box 1116 Telephone: (03) 529 5639 HEAVY DUTY TV/SPEAKER WALL-CEILING BRACKETS The MB~ and "'1u5 are heavy duty two platform mounting brackets designed for securing small TVs and speakers 10 walls, ceilings, desks or bench tops. ~en mounted both units can Disadvantages So far I have painted a fairly colourful picture of these imported European receivers. Readers could be forgiven for thinking of them as the Mercedes or Volvos of the vintage radio world. While they are unquestionably good quality receivers, there are a few unfavourable aspects about them. First, these up-market radios are not that good to work on. Many of the sets in my collection can be separated from their cabinets simply by removing the control knobs and two, or perhaps four, screws. Not so with some of the European varieties - there are lots of things to remove or disconnect before the chassis can be removed. Second, these European receivers invariably have a few (to us) nonstandard valves. The valves used may be reasonably common on the Continent but here, in the land of Oz, they can be virtually impossible to obtain. You want proof? Well try this. The The 220V transformer tapping on the Nordmende set is a bit low for Australian conditions. Hopefully, there is enough tolerance built into the set to withstand the extra voltage. be 360rotated degrees ~ · Nordmende has two ECC808s in its circuit. Try finding a calalog listing, then try to locate a couple of valves. Or, if you think that's an easy one, see how you go with the EMM803 tuning indicator. If you find a supplier of these I would like to know who and where. The big plastic-cased Philips has a UL41 valve. Although not unobtainable, it is by no means a common valve. An EM80 tuning indicator may also be a bit elusive to track down. Anyway, despite the good points and bad, my European receivers perform fairly well and are worthy additions to my collection. A good collection needs some variety and a few unusual receivers from abroad can provide just that. SC p.:.·::;('brs;,: ~ a~~~ ,l"4--_Jvi as well as being swivelled up or down to any viewing or listening angle. The metal platforms have predril/ed holes for mounting and are easily adjusted with a large a/fen key supplied with the unit. ~ Imported and distributed by: AlUS'.l'A ELECTRONICS Available through the following retsilers: David J Reid Electronics. All Electronic Components. 127 York Street. Sydney. 2000. NSW. (02) 267-1385. 118 Lonsdale St. Melbourne. 3000. Vic. (03) 662 3506. JANUARY 1991 45 Why replace your and $AVE $$$ with BOARD SOLUTIONS Pty Ltd .___ _M _O _T_H_E_R_e_o_A_RD __ s _ 10MHz XT, (640K) OK RAM 10MHz XT, (1 MB) OK RAM 31MHz XT286 OK RAM Baby 286 12MHz OK RAM 16MHz NEAT 286 OK RAM 20MHz 286 OK RAM 286, all-in-one, OK RAM 16MHz 386SX, OK RAM 20MHz 386SX, OK RAM 20MHz 386 NEAT, OK RAM 25MHz 386 NEAT, OK RAM 25MHz 386, 32K Cache, OK Neat 33MHz 386, 32K Cache, OK ___.l I M1010 115.00 M1000 149.00 M1020 199.00 M2015 299.00 M2040 399.00 M2045 449.00 M2010 545.00 M3000 845.00 M3005 895.00 M3002 1645.00 M3004 1795.00 M3010 1995.00 M3020 2395.00 CHIPS 1M RAM Chip - 100nS 1M RAM Chip - 80nS 256K RAM Chip - 1OOnS 256K RAM Chip - 80nS 4 X 256K RAM Chip, 1OOnS 4 X 64K RAM Chip, 120nS For VGA card 64K RAM Chip - 120nS NEC V20Chip NEC V20 Chip, 10MHz NEC V30 Chip, 10MHz 80387SX 16MHz Co-Processor 8087-2, 8MHz Co-Processor 2C87-8MHz (equiv 80287/8) 2C87-10MHz (equiv 80287/10) 2C87-12MHz (equiv 80287/12) 2C87-20MHz 3C87-16MHz (equiv 80387/16) 3C87-20MHz (equiv 80387/20) 3C87-25MHz (equiv 80387/25) 3C87-33MHz (equiv 80387/33) SIMM Module, 1MB 80ns SIPP Module, 1MB 80ns 29300 29380 29400 29480 29200 19.95 21.95 6.95 7.95 22.95 29212 29112 29000 29010 29020 29540 29500 29550 29555 29560 29565 29570 29575 29580 29585 29680 29690 9.95 4.95 24.95 39.95 49 .95 795.00 275.00 449.00 495.00 549.00 649.00 649.00 749.00 949.00 1099.00 225.00 225.00 INTERN. FLOPPY DISK DRIVES YE-Data 360K YE-Data, 720K/1.44M D3000 drive Plus Frame YE-Data, 1.2MB D5500 D3000 D3010 D5510 II~___M_tc_E_&_ J_o_Y_s_T_tc_K_s_ ~ 149.00 184.95 199.00 175.00 INTERNAL HARD DISK DRIVES I Kalok 20MB 40mS 399.00 D8100 Seagate 44MB /DE 28ms * D801 1 595.00 Conner 40MB /DE 25ms * D8012 795.00 Maxtor 42MB /DE 28ms * D8013 695.00 Maxtor 42MB /DE 19ms* 795.00 D8014 Maxtor85MB /DE 19ms* D8020 1195.00 Conner 105MB /DE 25ms * D8030 1395.00 Conner 212MB /DE 16ms* D8040 2195.00 *Alf /DE drives include controller card for 2xH, 2xF drives - see below for more details EXTERNAL FLOPPY DISK DRIVES For Amiga 500, 1000, 2000, 3.5in 880K For Amiga 500, 1000, 2000, 5.25in 360/880K For Commodore PC1 , 5.25in 3601720K 40/80 track For Atari ST series, 3.5in 720K For Atari ST series, 5.25in 360/720K 40/80 track For Amstrad PC1512/1640, 3.5in 720K For IBM XT, 3.5in 720K XT For IBM AT, 3.5in 1.44MB For IBM XT, 5.25in 360K For IBM AT, 5.25in 1.2MB For TOSHIBA laptop series, 5.25in 360K For TOSHIBA laptop series, 5.25in 1.2MB Joystick PC/XT/AT 3 Button Serial, Champ & Mat Mouse Mat D9500 249.00 D9510 299.00 D9520 D9530 299.00 299.00 D9540 299.00 D9550 D9560 D9570 D9580 D9590 269.00 299.00 329.00 299.00 329.00 D9600 349 .00 D9610 399.00 J1000 J1030 J1040 34.95 99.95 7.50 MONITORS Monitor, 14in TTL, Amber Monitor, 14in TTL, Green Monitor, 14in TTL, Paper White Monitor, 14in VGA 640 x 480 Monitor 14in VGA 1024 x 768 Monitor, 14in Multisync M9000 M9010 M9020 M9040 M9060 M9050 249.00 249.00 249 .00 749.00 799.00 899.00 1/0 CARDS 2 Ser. 1 Parallel Games, Parallel & 2 x Serial Chip Set & Cable suit 11040 Multi 1/0 Card XT only Multi 1/0 Card, 2 Ports all 4 drive types supported (XT Only) Parallel Printer Card (XT/AT) Serial PortCard X 1 (XT/AT) Serial PortCard X 2 (XT/AT) 1/0 Plus Card - XT Only Serial/Parallel Card - XT/AT 2 Serial, 2 Parallel, AT Multi-Serial Card , 4P-AT i1080 i1110 i1041 i1000 69.95 74.95 24.95 129.00 i1010 i1020 i1030 i1040 i1050 i1060 i1070 i1090 164.95 29 .95 54.95 64.95 99.00 64.95 84.95 245.00 VIDEO CARDS VGA Card, 800 x 600 (256K) VGA Card, 1024 x 768 (512K) Magic Combo CGA Card EGA Card Mono Hercules Card, 16MHz operation + Parallel Port V1000 V1010 V1020 V1035 199.00 299.00 V1040 89.95 129.00 179.00 DEALERS FOR BUILT-UP SYSTEMS REQUIRED IN ALL AREAS. PHONE OR FAX FOR DETAILS! The ·BARGAIN way to UPGRADE! Want to add a hard disk drive? Worried about the cost? Worry no more! Board Solutions has the perfect answer - low cost, top performance IDE Hard Disk Drives in your choice of brand and size. The latest in drive technology at an affordable price! Auto-parking IDE drives have most of the controller on the driv~ itself: the controller card (which swts 2 hard and 2 floppy drives) is very much smaller than you're used to! Easy to install - easy on the pocket! THIS MONTH'S SPECIAL: 44 MB 28ms Se~ate IDE Hard Disk With c-ontroller - ~ THIS MONTH ONLY: s595 OTHER IDE HARD DISK DRIVES FROM BOARD SOLUTIONS: Conner 40MB Maxtor 42MB Maxtor 42MB Maxtor 85MB Conner 105MB Conner 212MB IDE IDE IDE IDE ID!:; IDE 25ms 28ms 19ms 19ms 25ms 16ms D8012 D8013 D8014 D8020 D8030 D8040 795.00 695.00 795.00 1195.0(; 1395.00 2195.00 YES! All our prices INCLUDE sales tax AND 12 Months Warranty! BOARD SOLUTIONS IS YOUR ONE-STOP PC PC: Upgrade it now Board Solutions! I POWER SUPPLIES L2-30- W-att - P-SU - S-ui_tT _o_w_e_r -C-a s_e_ P_2_0-20- 19_5__, .oo 220 Watt PSU Suit Baby T Case 150W PSU, Circuit Board 150W Switching PSU - XT 200W Switch PSU - Baby AT 200W PSU, Baby AT, L Type 230W Switching PSU -AT 200W PSU With Battery Backup 150W PSU Cap. 220n F/200V P2030 P1500 P1510 P2000 P2010 P2200 P2040 P9000 149.00 85.00 124.00 149.00 149.00 195.00 695.00 3.95 KEYBOARDS 101 Key Keyboard, XT/AT 101 Key Keyboard + TrackBall 99.95 174.95 K1010 K1020 RAM CARDS RAM Card, OK RAM, XT only 2MB RAM Cd-, OK LIM/EEMS AT 2MB RAM Cd, OK LIM/EEMS XT 6MB RAM Card, -OK RAM 8MB Fast Card Suit 20MHz +SX 32 Bit RAM Card 25 + 33MHz R1000 R1010 R1020 R1030 R1040 R1050 99.00 265.00 245.00 295.00 299.00 349.00 DISK CONTROLLER CARDS Floppy Disk Card, 4 Ports 360K Disk Cont 4 port, 2In 2Ex or 4In Floppy Disk Card All Drives ESDI Hard Disk Cont Card -AT ESDI HOD/FOO Card - AT Hard Disk Cont, 1 :1 lnt. AT HOD/FOO Cont, 1 :1 lnt. AT Hard Disk Cont, 1:1 lnt. ALL, AT HOD/FOO Cont, 1:1 int, ALL, AT SCSI HOD/FOO for AT Hard Disk Controller, XT Hard Disk Controller, RLL-XT /DE (AT BUS) HDDIFDD Card IDE(ATBUS) E1000 E1030 E1010 E1040 E1050 E1060 E1070 E1080 E1090 E1105 E1110 E1120 E1200 55.00 134.95 99.00 349.00 425.00 245.00 275.00 249.00 285.00 275.00 134.95 154.95 89.95 HDDIFDDl2S11P/ 1GCard I E1210 149.00 C1000 C1005 C1010 C1020 C1030 C1040 C1050 C1070 C1080 C1090 125.00 CASES Hinged, Baby AT Full Size Hinged AT Case Hinged Baby ATw/200W PSU Slimline 'XT' or 'AT' with PSU 3.5in Hard Disk Ext. + Cable 5.25in Floppy Disk Ext. + Cable 5.25in Full Height Ext. + Cable Baby Tower Case AT Baby Tower Case+ 200W PSU Tower for 6 Dev. (4 front, 2 rear) Tower for 6 Dev. (4 front, 2 rear) & 200W PSU Tower for 6 Devices, (6 front) Tower for 6 Devices, (6 front) + 200W PSU Case, hinged XT 199.00 249.00 295.00 99.00 134.95 125.00 189,00 325.00 399.00 C1100 C1120 499.00 C1130 C1140 499.00 FAMOUS BRAND PANASONIC PRINTERS If you're looking for the ultimate in quality, reliability and value,look no further than these outstanding models from Panasonic....: a brand to trust! 144cps 192cps 240cps 330cps 192cps 192cps 240cps 9 pin 80 col 9 pin 80 col 9 pin 80 col 9 pin 132 col 24 pin 80 col 24 pin 132 col 24 pin 132 col P5000 P5010 P5020 P5030 P5040 P5050 P5060 $349 $449 $499 $949 $649 $1099 $1249 BUILT, TESTED AND FULLY GUARANTEED! 286 12MHz SYSTEM Includes • • • • • • • • 8112MHz (Landmark 16MHz) 1MB RAM on board 1.2MB (5-1/4in) Floppy Disk Drive 42MB 28ms Hard Disk Drive Serial, Parallel and Games Ports Floppy Controller Enhanced 101 Key Keyboard Hinged "Baby AT" case and 200W power supply • 14in Paper White Monitor & Mono Hercules Card 399.00 95.00 INTERFACE CARDS 48 Line 1/0 Card F1130 Serial RS-422 Adaptor F1140 Industrial 1/0 Card F1150 Universal Wire-wrap Card F1030 Dual Serial RS-422 Card F1040 80286 Speed-up Card F1050 IEEE 488 Interlace Card F1060 IEEE 488 Interface Card- National Compatible F1070 A-D/0-A Converter, 12 bit, 1 Ch. F1080 Clock Card - XT F1100 EPROM Writer Card F1110 Games Card- 'XT'& 'AT' F1120 X2859 110.00 135.00 445.00 125.00 195.00 495.00 445.00 399,00 499.00 12.75 • 14 day money-back guarantee (except software) • 12 months warranty on all our products • Mail orders are our speciality • Road Freight on normal size items $9.00 • Insurance $1.00 per $100 of order value • All prices INCLUDE sales tax • We accept Visa, Bankcard, Mastercard and Post Office COD • Call tor very latest products and prices • Special prices apply for month of publication, or while stocks last • Leasing facilities available: just ask! • Government pricing available on request. • KEY tor products on these pages: BOLD products are new products, BOLD prices are new low prices. ENHANCEMENT COMPANY $ 1795 386SX 16MHz SYSTEM • • • • • • • • • 8116MHz (Landmark 21 MHz) 1MB RAM on board 1.2MB (5-1/4in) Floppy Disk Drive Hard/Floppy Controller 42MB 28ms Voice Coil Hard Disk Drive 2 Serial, 1 Parallel Ports 16 Bit 256K VGA Card (exp to 512K) Enhanced 101 Key Keyboard Mini Tower C;ise with LED display and 200W power supply • 14in Super VGA 1024 x 768 Colour Monitor, 0.28mm dot pitch NETWORK SK Ethernet 8 bit with 'T' Adaptor N1000 16K Ethernet 16 bit with 'T' Adaptor N1017 Ethernet 50 Ohm Terminator N1020 All this for only Includes 595.00 199.00 49.95 245.00 35.00 CALL (02) 906 5696 FOR THE DEALER NEAREST YOU! PRINTERS! ...······································..• HIGH QUALITY .•• JSE SYSTEMS . • X3862 All this tor only $ 2995 386 25MHz SYSTEM Includes • • • • • • • • • • 8125MHz (Landmark Speed of 47MHz) 32K SAAM Cache 1MB RAM on board 1.2MB (5-1/4in) Floppy Disk Drive Hard/Floppy Controller 42MB 28ms Voice Coil Hard Disk Drive 2 Serial, 1 Parallel Ports 16 Bit 256K VGA Card (exp to 512K) Enhanced 101 Key Keyboard Midi Tower case with LED display and 200W power supply • 14in Super VGA 1024 x 768 Colour Monitor , 0.28mm dot pitch $ 3995 X3865 All this for only FOR MS-DOS please add $100 ALL SYSTEMS INCLUDE A 12 MONTH "BACK TO BASE" WARRANTY ·····································J ~SHUt4,4, BOARD SOLUTIONS Ply Ltd PO BOX 1120, LANE COVE NSW 2066 TEL (02) 906 5696 FAX (02) 906 4592 Build this 2-tone alarin Inodule You've just finished designing an alarm project and you need an ear-catching alarm to go with it. If that's the case, then this alarm sounder is the go. It produces a melodic 2-tone sound, packs quite a punch for its size and uses only a few parts. By DARREN YATES This circuit was basically designed for all those times we needed a simple circuit that made an "easy on the ears" sound. It's very similar to the alarm siren in the Egg Timer project published in the November 1990 issue of SILICON CHIP. It's perfect for any alarm type application such as a water level monitor, automotive gauge monitor, or in a kid's game to indicate a winner. The module uses "easy to get" parts, can be built in a couple of hours and shouldn't cost any more than about $10 to make. It has only one input point and is simple to operate. Just connect the control input to the positive supply rail to make the alarm sound, and ground it to turn the sound off again. Circuit diagram Let's take a look at the circuit diagram in Fig.1 and see how the circuit works. The module uses a single 4093 Schmitt trigger NAND gate IC, a few transistors, a couple of diodes and little else. Gate IC1a is connected up as the control oscillator. This determines how fast the circuit toggles between the two tones. If pin 1 is connected to the positive supply rail, the gate is enabled and the circuit begins to oscillate. If you look at the truth table in Table 1, this will show you why. If one of the input pins of the gate is low, then it doesn't matter what you do with the other, the output will always remain high. This corresponds to lines 1 and 2 of the truth table as well as lines 1 and 3 since it doesn 't matter which input is taken low. However, once you take one of the input pins high , the output then becomes the opposite of the value on the other input pin, matching lines 3 and 4 as well as lines 2 and 4 in the truth table. The NAND gate here is a special type known as a Schmitt trigger gate. Normal gates have a very small threshold area or "hysteresis" level where an input voltage causes a change in the output level. For a normal 4011 NAND gate, the threshold level is about half the supply voltage plus or minus a few millivolts. The Schmitt trigger gate, however, The parts for the 2-tone chime are all installed on a small PC hoard. The project can drive a small loudspeaker to good volume & is ideal for a wide range of applications requiring an audible alarm (eg, door chimes, games & automotive monitors). 48 SILICON CHIP ----------------------+3V-15V 16VWI 10 + 01 .,, 1 PCB,codeSC08111901, 73x 46mm. 5 PC pins 1 8Q 57mm loudspeaker 47k 1M 120k Semiconductors 1 4093 quad 2-input NANO Schmitt trigger (IC1) 1 BC558 PNP transistor (01) 1 BC338 NPN transistor (02) 1 BC328 PNP transistor (03) 3 1 N914 signal diodes (D 1-D3) -:- 150k B ELJc VIEWED FROM BELOW TWO-TONE CHIME MODULE Fig.1: the circuit is.based on three Schmitt trigger NAND gates: ICla, IClc & ICld. ICla is the control oscillator & sets the rate at which the circuit toggles between the two tones generated by IClc & ICld. The outputs from the tone oscillators are then mixed & fed to an audio amplifier (Ql, Q2 & Q3). has a fairly large area, usually about 1/3rd of the supply voltage. This means that the input voltage must go below 113rd of the supply voltage before the gate recognises it as a low and above 2/3rds of the supply rail for it to be seen as a high. So, if we have a 9 volt supply rail then the upper threshold is about 6 volts and the lower threshold is about 3 volts, giving us a hysteresis level of about 3 volts. By adding just two components, we can turn this gate into a simple squarewave oscillator. Looking back at the circuit diagram , notice that there is a lMQ resistor connected between the output and one of the input pins (pin 2), and a 0.lµF capacitor from that input pin to ground. Ifwe assume the other input is held high, then this is how the oscillator works. Initially, the capacitor has no voltage across it and the gate recognises this as a low. If you look back at the truth table in Table 1, you can see that one high input and one low input gives us a high output. The capacitor now begins to charge up via the current flowing from the gate output and through the lMQ resistor. The output remains high until the voltage across the capacitor reaches 2/3rds of the supply voltage. When this happens, the gate realises it now has a high on both inputs, and so pulls the output low. (Check this again PARTS LIST on the truth table shown below). The capacitor now begins to discharge through the lMQ resistor, out through the low output. Once the voltage falls below 113rd of the supply voltage, the gate sees a low on one of its inputs and so sends the output high again. The capacitor again begins to charge up through the lMQ resistor until it reaches the upper threshold level and so the cycle c.ontinues. There are three of these oscillators in the circuit, formed by gates ICla, c & d. ICla forms the control oscillator while IClc and ICld are the two tone oscillators. The frequency of ICla is much lower than the other two so that the two tones can be easily distinguished. The frequency of this type of oscillator can be easily varied by changing either the resistor or capacitor value. Reducing the value of either component increases the frequency and increasing the value decreases the frequency. TABLE 1 INPUT A INPUT B OUTPUT (pin 1) (pin 2) (pin 3) Low Low High High Low High Low High High High High Low Capacitors 1 100µF 16VW electrolytic 1 10µF 16VW electrolytic 1 0.1 µF metallised polyester (greencap) 2 .018µF metallised polyester 1 .0039µF metallised polyester Resistors (0.25W, 5%) 1 1MQ 2 10kQ 2 150kQ 1 1kQ 1 120kQ 1 68Q 1 47kQ Miscellaneous Hookup wire, solder, etc The outputs from these two oscillators are then coupled together by two lOkQ resistors to a common .0039µF capacitor. These components form a very simple audio mixer. The signal is then fed to the base of transistor Ql, which is biased on by the 4 7kQ resistor. Transistors Ql-Q3 together form a low-power audio amplifier. Ql provides the voltage gain and biasing for the push-pull output stage based around transistors Q2 and Q3. The 68Q resistor and diode D3 provide a voltage drop of about 1 volt between the bases of transistors QZ and Q3 to reduce crossover distortion, to provide a clean output signal. They also set the quiescent current to about 5mA. (You could even use this amplifier circuit for your own projects!) The amplified audio signal appears at the junction of the emitters of Q2 and Q3 and is coupled to the loudspeaker via a lO0µF capacitor. Construction If you make or buy the PC board, check that there are no shorts or breaks in any of the tracks. If there are JANUA RY 1991 49 Fig.2: be sure to orient all polarised parts correctly when installing them on the PC board. These parts include the IC, transistors, diodes & electrolytic capacitors. any, correct them now before you do any soldering. Once you're happy that everything is OK, solder in the PC pins and the wire links. Next install the resistors and the greencaps. Use the wiring overlay diagram to make sure you have them in the right place on the board. Now install the electrolytic capacitors. Check that you have them correctly installed before you solder them in. Once you've done that, solder in the diodes, transistor and the IC. Testing If you're happy that everything is OK, you can now test the circuit operation. First, connnect a wire link between the control pin and the posi- CAPACITOR CODES 0 0 0 0 Value IEC Code 100n 0.1µF .018µF 18n .0039µF 3.9n EIA Code 104 183 392 Fig.3: use this full-size artwork to etch your own PC board & to check the board for etching defects. tive supply pin. If you now connect up a voltage supply of between 3 and 15 volts, you should get an instant chime from the speaker. Disconnect the power and remove the link between the positive supply and control pins and replace it with a link from the control pin to the ground pin. If you again switch on the power, you should hear nothing. If this doesn't work, disconnect the power and check the board for any accidental solder splashes between the tracks. You should also check that you have all the components correctly installed. Experimenting Since we are using only dirt-cheap and common components, you may like to experiment a bit with the circuit in the following way: To increase the frequency at which the circuit cycles between the two tones, decrease the lMQ resistor connected to ICla. You will notice some strange effects, the lower in resistor value you go, but don't go below about lOkQ otherwise the gate begins to dissipate too much power. You can decrease the frequency also by increasing the resistor value. If you want to change the frequency of the actual tones themselves, you can increase or decrease the value of the 150kQ and lZ0kQ resistors connected to IClc and ICld respectively. As before, increasing the resistor value decreases the frequency and decreasing the resistor value increases the frequency. Again, don't go below l0kQ. The volume of the chime can be increased by replacing the .0039µF capacitor with a larger value - say .0082µF. Be careful though, as this increases the current consumption of the amplifier from about 30mA to 90mA. Don't go above .0lµF or you may end up damaging the output transistors. Most importantly, do not take the control input higher than the circuit supply voltage otherwise you will kill the IC. What you can do is to run the chime module from an existing power supply and generate the control signal from that supply voltage. SC RESISTOR CODES 0 0 0 0 0 0 0 0 50 No Value 4-Band Code (5%) 5-Band Code (1%) 1 2 1MQ 150kQ 120kQ 47kQ 10kQ 1kQ 68Q brown black green gold brown green yellow gold brown red yellow gold yellow violet orange gold brown black orange gold brown black red gold blue grey black gold brown black black yellow brown brown green black orange brown brown red black orange brown yellow violet black red brown brown black black red brown brc,wn black black brown brown blue grey black gold brown 1 2 SILICON CHIP For Features and Performance ... Upgraded tor The Nineties! T D z For Features and Performance ... Prices include TWO x1/x10 switch probes 3 1/2 digit large LCD display Memory for relative measurements Data hold function Diode and Transistor testing ◄ ff~ 4 1/2 digit large LCD display Measures capacitance 200kHz frequency counter Diode and Transistor testing · High sensitivity- 1mV/div Stable low drift design 8 divisions of displayed dynamic range with accurate distortion-free waveform measurement Special TV sync separ11tion circuits for measurement of video signals Delayed sweep function (OS7040A) ±3% accuracy Cursors for direct measurement of waveform voltage, time and frequency 20MHz bandwidth Convenient XY operation for measuring phase differences between two waveforms Variable sweep control incorporating x10 magnifier Uncal and trigg-er warning lights TV-V & TV-H triggering Trigger hold-off 3 1/2/digit large LCD display Measures capacitance Measures Temperature-20 to +15ffC 0S7020A $650 ex tax $773.50 inc tax* 0S7040A $1045 ex tax $1243.55 inc tax• 1mV max sensitivity Similar performance to OS7020A 0S8020R $1045 ex tax $1243.55 inc tax• - ·supported &Serv.iced Australia-wide by Elmeasco Instruments Pty Ltd N SW (02) 736 2888 Vic (03) 879 2322 Old (07) 875 1444 S.A. (08) 344 9000 W.A. (09) 470 1855 3 1/2 digit LCD display Memory mode for relative measurements Data hold function Slim, compact construction Supported & Serviced Australia-wide by Elmeasco Instruments Pty Ltd N SW (02) 736 2888 Vic (03) 879 2322 Old (07) 875 1444 S.A. (08) 344 9000 W.A. (09) 470 1855 You've Gotta Getta Goldstar from: You've Gotta Getta Goldstar from: A.C.T. John Pope Electrical 80 6576N.S.W. D.G.E. Systems (049) 69 1625e W.F.Dixon (049) A.C.T. John Pope Electrical 80 6576 !iJ....W,. D.G.E. Systems (049) 69 1625 • W.F.Dixon (049) 69 5177 • Macelec (042) 291455 • Newtek (042) 271620 • Novacastrian Electronic Supply [0_§)_62 1358 e Obiat Pty Ltd 698 4776 e Digitel 709 6511 e Geoff Wood 427 1676 OUEENSLAN!l St Lucia Electronb 252 7466 • B.A.S. Audiotronics 844 7566 • The Electronics Shop (075) 32 3632 • Solex (Townsville)(077) 72 4466 • Xanthos Electrical (079) 27 8952 S.AUSTRALIA Force Electronics (08) 212 5505 VICTORIA G.B. Telespares 328 4301 e The Electronic Components Shop 670 6474 • Factory Controls (052) 78 8222 • Mektronics 587 3888 • Truscott Electronics 723 3094 W AUSTRALIA Atkins Carlyle 481 1233 • Leda Electronics 361 7821 PAPUA NEW GUINEA TE (P.N.G.) Pt Moresby 25 6322 Lae 42 6246 69 5177 • Macelec (042) 291455 • Newtek (042) 271620 • Novacastrian Electronic Supply (049) 62 1358 e Obiat Pty Ltd 698 4776 e Digitel 709 6511 e Geoff Wood 427 1676 QUEENSLAND St Lucia Electronics 252 7466 • B.A.S. Audiotronics 844 7566 • The Electronics Shop (075) 32 3632 • Solex (Townsville)(077) 72 4466 • Xanthos Electrical (079) 27 8952 S.A!ISTRALIA Force Electronics (08) 212 5505 VICTORIA G.B. Telespares 328 4301 e The Electronic Components Shop 670 6474 • Factory Controls (052) 78 8222 • Mektronics 587 3888 • Truscott Electronics 723 3094 W AU.s.TRALIA Atkins Carlyle 48 1 1233 • Leda •Electronics 361 7821 PAPUA NEW GUINEA TE (P.N.G.) Pt Moresby 25 6322 Lae 42 6246 *Recommended prices only *Recommended prices only I I I I I I ORDER FORM I 1 USE THIS FORM FOR ALL YOUR SILICON CHIP ORDERS S TBSCRIPTION: a a U RATES: NEW SUBSCRIPTION Month To Start_ __ _ _ _ __ (PLEASE TICK ONE) 2 YEARS (24 ISSUES) 1 YEAR (12 ISSUES) RENEWAL: Sub No. _ _ _ _ _ _ Start In, _ _ _ _ __ Australia Australia With Binder NZ & PNG (Airmail) Overseas Surface Mail Overseas Airmail □$A84 □$A1O5 □$A13O □$A13O □$A24O □$A42 □$A53 □$A65 □$A62 □$A12O GIFT SUBSCRIPTION: Month To Start _ _ _ _ _ _ __ ,, GIFT SUBSCRIPTION DETAILS ~ Mr/Mrs/Ms: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ -t 0 C') ,, 0 Address: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ < -t :E iii "l'I Please send me _ _ _ _ _ Sports Shirt(s) <at>$A24 95 _ _ _ _ _ _ _ _ _ Postcode _ _ _ _ __ _ __ 0 :II 3: SILICON CHIP BI ·o including postage (NZ add $A3) Size:_ _ _ _ s, M, L, XL, XXL Total $-r,___ _ __ s 'TI ~ Yes! Please send me _ __ SILICON CHIP binder(s) at $A 14.95 each Please send me._ _ _ _ _ Sloppy Joe(s) <at>$A27 95 g (including postage) TOT AL $__ _ _ _ _ _ _ _ _ _ _ _ including postage (NZ add $A3) .:j (Overseas Orders add $A3 each for postage) C z E iii :E -t 0 IA Size: _ _ _ _ s, M, L, XL, XXL Total$,--.__ __ $A5.00 each (includes postage). Overseas orders add $A 1.00 per issue for postage. ISSUE YEAR ISSUE YEAR ISSUE YEAR ISSUE YEAR C') C -t -t :E m 3: ► C) ► TOTAL $A !:::! z m Enclosed is my cheque/money order for$ _ _ _ _ _ __ or please debit my Card No. r7i La.I r;,:-iri. lffi] Mr/Mrs/Ms: _ _ _ _ _ _ __ _ _ _ __ _ __ Lw.l Address: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Card expiry date Signature _ _ _ _ _ _ _ __ 24 Hour Fax Service (02) 979 6503 Send the coupon with your Credit Card Details. 24 Hours, 7 Days a week. 52 SILICON CHIP _ _ _ _ _ _ _ _ Postcode: _ _ _ _ _ __ _ Subscription Hotline Telephone (02) 979 5644 9am-5pm Mon-Fri and quote your Bankcard, Visa Card or MasterCard No. and expiry date. Detach and Mail to: FREEPOST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COI_LAROY BEACH NSW 2097 No stamp required in Australia I PRODUCT SHOWCASE I Squeeky clean filters from Jaycar Concord, NSW 2137. Phone (02) 747 1888. vacuum pickup and place and has slots for extraction tools. Optional polarising pegs can be provided and the socket is available in 20, 32, 44, 52 and 68 terminal versions. For further information, contact Adilam Electronics Pty Ltd, PO Box 131, Bulleen, Vic 3106. Phone (03) 846 2511. Whether you have a computer system or a hifi, these two or four outlet power filters from Squeeky Clean will help protect your equipment from mains hash or voltage spikes. Both are rated at 10 amps maximum and contain varist'ors as well as filter components. The two-outlet job sells for $109 while the bigger four-outlet model is $269. Check them out at your nearest Jaycar Electronics store or obtain yours by mail order from PO Box 185 Surface mount chip carrier socket Portable tape streamer for data backup This new low profile PLCC socket has visible internal solder tails, making for easy solderability with all common reflow processes. It uses a high pressure contact system which is claimed to eliminate the need for gold plating while assuring a reliable cost effective surface mount socket for leaded chip carriers. The socket has a centre pad for Most of us have suffered the problem of losing data through system corruption or just a bad floppy. The new BIT tape streamer from Banksia Information Technology is designed for quick large-quantity data storage on cassette - up to 60MB! File-by-file backup can take place at up to 5MB/minute and the whole system is menu driven. It even takes High capacity laser printer This new printer from Facit, designated the model P8100, is suitable for applications ranging from word processing to graphics and desktop publishing. Its standard features include dual Centronics parallel and RS-232C serial interfaces, 512 kilobyte memory, 200 sheet paper tray and 300 dots per inch resolution. Emulations provided in the base unit are HP Laserjet II, IBM Personal Printer Data Stream (PPDS), and the IBM 7372/ HP7475A (HPGL) Graphics Language. Options include memory expansion of 1, 2 or 3.5Mb, a 500-sheet document feeder, 75 envelope feeder, a wide range of font cards and soft fonts for the HPLJII and PPDS emulations, and a special input paper tray for A5 size sheets. Also available as an option is the original Adobe Postscript language in either 17 or 39 font versions. Although designed as a heavy duty "work horse", the P8100 takes up only a small amount of space and has a low noise output (50dBA), making it ideal for the normal office in LAN, mini or mainframe applications. For further information, contact Elmeasco Instruments Pty Ltd, 18 Hilly Street, Mortlake, NSW 2137. Phon!:) (02) 737 2888. JANUARY1991 61 once only investment of $33.50 from Microtroriics Pty Ltd, 305 Morphett St, Adelaide, SA 5000. Remote control tester from J. V. Tuners Acoustimass system for professional use Bose has brought out a professional version of their Acoustimass subwoofer and satellite system which is called the Bose 403. While their domestic version has a nondescript bass enclosure, the 403 has a sculptured suitcase look about it, with the base ports underneath the rugged carrying handle. The satellite speakers use four tweeters, each of which can be separately angled to give an overall wide dispersion of the sound. Crossover frequency from the bass to treble enclosures is at 180Hz. Maximum power input is 250 watts RMS or 400 watts peak. Overall frequency response of the system.is quoted as 45Hz to 20kHz. For further information, contact Bose Australia Inc, 11 Muriel Ave, Rydalmere , NSW 2116. Phone (02) 684 1022. care of when the cassette is full. The tape streamer doesn 't require an extra power supply, as it obtains this via the BIT controller card, which just fits in the back of any PC. It also supports MS-DOS 2.0 and higher. It is available as a package containing software, controller card and manual for $1296 plus tax. For further details, contact Banksia Information Technology on (02) 418 6033 or Fax (02) 428 5460. AM/FM receiver for alternative lifestyles Are you "going bush" where you'll be out of reach of normal mains power or even supplies of batteries? If so, this little AM/FM receiver could be for you. It has four possible sources of power. You can use it with ordinary AA cells but why would you want to? Instead, most people would use the top- mounted solar cells to keep its internal rechargeable cells up to 62 SILICON CHIP scratch. Or if you have mains power available, you can put the radio on charge for a few hours. Finally, if you are out "in the sticks" and the you want to listen in the clead of night, a few cranks on the handle of the internal dynamo will make a few minutes of listening available. Frequency coverage is 88-108MHz on the FM band or 525-1650kHz on the AM band. Never buy a battery again, with a Designed to test any infrared or ultrasonic remote control, this unit confirms their operation with a light emitting diode and a piezo speaker. Quite a handy unit for the TV and video serviceman, the unit is priced at $85 plus $4 postage and packing from J.V. Tuners. Contact them at 216 Canterbury Road, Revesby, NSW 2212. Phone (02) 774 1154. Weller Pyropen has piezoelectric lighter Here is a deluxe portable gas powered soldering iron for servicemen and technicians. Beautifully made and housed in a steel carrying case, it has pushbutton lighting by means of a piezoelectric element. It comes with a number of bits and a blowtorch fitting and has a foam pad inside the case for wiping the bit clean. Priced at $169.95, the Weller Pyropen is available from David Reid Electronics, 127 York Street, Sydney, NSW 2000. Phone (02) 267 1385. 486 upgrade for 386 computers Do you have an application where a 386 computer is still not fast enough? You'd like a 486 motherboard _but can't afford it, right? Well now there is a 486 daughterboard upgrade at a much lower price. Called the GO!486, it can plug into the socket of your 16, 20 or 25MHz 386 and 387 processor to deliver zero wait state processing while allowing the motherboard to run at its original speed. While doing so, it is claimed to deliver 97% of the performance of a 486 motherboard. Installation can be done in minutes and there is no need to reformat the hard disc or to transfer data. For further information, contact · Computer Connection, Level 3, 220 Pacific Highway, Crows Nest, NSW 2065. Phone (02) 957 6719. Low cost multimeter fits in your pocket This compact digital multimeter slips easily into your shirt pocket yet has just about all the functions you want, at a low price too. It has a 3½digit readout, ±0.7% accuracy for DC voltage measurements, ±1 % accuracy for DC current and ±1.2% accuracy for AC voltage (two ranges: 200V and 750V). There are five resistance ranges, 2MQ, 2ookn, 20kQ, 2kQ and 200n. As well, there is a diode test range and a 10 amp DC range. And the price? Just $39.95 from Altronics of Perth. Phone (09) 328 1599. HP's most powerful desktop computer Hewlett Packard has introduced its most powerful desktop personal computer, the 25MHz 80386 based Vectra 386/25. The new machine employs high performance embedded controller hard disc drives, HP 's super VGA display with extended resolution, two megabytes of near-zero wait state memory and a 32K memory cache. It is claimed to be capable of running applications up to 25% faster than 20MHz cache-based 386 systems and up to 50% faster than non-cached systems. 12-bit analog to digital converter Now available is a new 12-bit 10MHz sampling analog to digital converter which incorporates subranging, · sample-hold, internal reference and 3-state output buffers. Laser trimming and customised gate arrays deliver a high performance such as total harmonic distortion and signal to noise ratio of 70dB and 2- Hard drive capacities of 42, 84, 170 and 340 megabytes, with access times of 17-19 milliseconds, are available. A single 3.5-inch or 5.25-inch floppy drive may be fitted. Memory is expandable from the base of 2 megabytes to a maximum of 32Mb, using single inline memory modules (SIMMs). Base price of the new HP Vectra 386/25 , with no hard drive, is $9145. With an 84MB drive, the price is $11 ,870 and with a 170MB drive, the price is $13,574. For further information, contact Hewlett Packard Australia Ltd, 3141 Joseph St, Blackburn, Vic 3130. Phone (008) 033 021. tone intermodulation distortion of 75dB. A small signal bandwidth of 65MHz and a full power bandwidth of 40MHz assure fast response to transient signals. Integral and differential nonlinearity are specified at ±1LSB for input frequencies up to 5MHz, while offset and gain temperature coefficients are specified at ±25ppm/°C typical. Input voltage range is ±1.25 volts while power requirement is for ±15V and JANUARY1991 63 Good quality project kits from Dick Smith Electronics Pictured here are two of the recent kits produced by Dick Smith Electronics for SILICON CHIP projects. Good quality components are used throughout and the presentation is topped off with fine screen printed panels. Dick Smith Electronics kits are outstanding not only for their component quality but also for their instruction manuals which usually provide diagrams and information not in the original project articles. While the SILICON CHIP Dual 50V Power Supply and Digital Capacitance Meter are highlighted here, Dick Smith Electronics has a large range of other kits originally developed and published in this magazine. See them at your nearest Dick Smith Electronics store. Australia. There are steel speaker grilles to suit various sizes, chrome catches, plastic corner pieces, different styles of handles, and steel dishes to suit XLR sockets. The prices are quite reasonable. To find out more, contact Sound Australia, 28 Walker Street, Dandenong, Vic 3175. Phone (03) 7911622. ±5V rails. Typical applications include spectrum, transient, vibration and waveform analysis. The device is also suited to infrared imaging, radar, sonar, video digitisation, medical instrumentation and high speed data acquisition systems. For further information, contact Elmeasco Instruments Pty Ltd, PO Box 30, Concord NSW 2137. Phone (02) 736 2888. Hardware for PA loudspeaker systems If you are building a PA system for road use, you'll be interested in this range of cabinet hardware from Sound 64 SILICON CHIP New inkjet printer from Hewlett Packard Hewlett Packard have replaced their Deskjet and Deskjet PLUS printers with the new HP Deskjet 500 model which offers more fonts, better font spacing, water-resistant ink and compatibility with Microsoft Windows 3.0. As with previous models, it has 300 dots per inch resolution and uses plain paper. It outputs text at three pages a minute and graphics at two pages a minute. The Deskjet 500 has four internal fonts: CG Times, Letter Gothic, Portrait and Landscape Courier. Each typeface has medium, bold, italic and bold italic treatments and comes in 6 and 12 point sizes except for Landscape Courier which also comes in 24 point. Kerning is available for a more professional look. As well, there are four new font cartridges offering two decorative fonts, Dom Casual and Brush, in addition to Garamond, CG Triumvirate and Century Schoolbook typefaces. For a really quiet printer then, have a look and a listen to a HP Deskjet 500. It is priced at $1266.00. Enquiries to your HP printer dealer or to Hewlett-Packard Australia Ltd, 31-41 Joseph St, Blackburn, Vic 3130. Phone (03) 895 2676. Heavy duty relay from Takamisawa This heavy duty SPST relay from Takamisawa has a 12V coil and 25 amp 250VAC contacts. It could be used as a power supply crowbar, for motor starting or for other heavy duty applications. It's available from David Reid Electronics, marked down from $13.95 to $7.50. Get 'em while you can. The address: 127 York St, Sydney, NSW 2000. Phone (02) 267 1385. wpoD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS .. . WOOD FOR: C COMPUTER BITS & PIECES Cables Null Modems Switchable RS-232 Lead Printer LNds IBM Parallel lyf/1/ 1.8m 4.0m 10m Easy and ~utck to change configurations with DIP" switches built mto both 25-pin ·o· plugs. Allows various combinations of TXD and RXD as well as 025 Type Male to Female 025 Cable type 2m long 114.95 29.95 75.00 ~'{%, 1¥f:! type. Male to Female 2m ffl4 .95 ~~fttt~ni ~~~~~tiler end 5m .oo ana pins 2.3.4d5.s.a.11.14.19 & 20 10m 75.00 at terminal en . Extension Leads Five connecting wires Including 025. Male/Female Male/Male ground, two wires connected Female/Female. All 2m long $24.15 0 MonltorLNds i~a~:d ~o~Tucts. 09. Male/Female Male/Male Length 2m $39.95 Female/Female. All 2m long 124.95 . - - - - - - - - - - Sm long $29 .95 Keyboard Extensions 1.Sm curly cord $9.95 Stir/al to 09 Convetter D 9Female to 025 Male 2m long $19 .95 /EC Power Cord 1.8m ~ er: 0 I.I.. Cl 0 ~ ~ ter: 0 I.I.. Cl 0 ~ ·o· ■ FAX/Modem/ Phone Protec or Protects both telephone line and f&;:~ ~~k~~~~~ul)g~!n~Pso 0 I.I.. Cl 0 ~ ~ ~ er: Centronics 50 Wi!.'f. Male to male, female to female or male to female. All 1.Sm $34.00 9 PI r to 25 PI n Adapto I er: I.I.. Cl 0 ~ Vdc 200mV, 2V, 20V, 20CN. 1000V Vac 200mV, 2V, 2rN. 200V,J~rN Ade 20011A. 2mA. 20mA. 2u...-nA. 2A. 20A. Aac 200uA, 2mA. 20mA. 200mA. 2A. 20A Ohms 200!1, 2k{l 20k{l 200kn, ' 2MQ, 20MO Frequency 2kHz 20kHz, 200kHz ciacitance 2nF. 20nF. 200nF, 2µF. $6.95 A IGA Extension able!i D23 Male/Female. Mate/Male. Feniale/Female. All 2m tong $29.95 Data Switch Boxes ComTHt-The Ultimate/ If you're a professional user get the data sheets from us. There's a 1 Mght for you.1315.00 COMTEST 212 285.00 COMTEST 225 425.00 Made To Order $7.50 Compu er aper $6.95 $7.95 60osm bond, 66 lines per Pi!ll~J 2000 sheets $41.95 1th 00 analog bar graph e Autoranging or manual selection • 8 Functions • Vdc, Vac. Ade, Aoc, Ohms, Diode, Frequency, Capacitance Data hold • Memory offset Ranqs Vdc 200mV, 2V, 20V, 20CN. 1OOOV Vac 200mV. "N, 2(N, 200V, 75(J,/ Ade 20011A. 2mA. 20mA. 200mA. 2A, 20A. Aac 200uA. 2mA. 20mA. 200mA. 2A, 20A Ohms 200!1, 2kQ 20kn, 200kn, 2Mn, 20MO Frequency 2kHz 20kHz, 200kHz ciacitance 2nF, 20nF, 200nF, 2µF, Custom Cable Service Available MEMOREX GE0 Mod 198 e 3 112 digit plus 41 segment ·o•r,,,. 510 terminator "T" pieces 3 females 2 females. 1 male GENUINE PREMIUM GRA SKS 51/4 2S/2D $16.95 per 10 5 1/4 2S/HD $24.95 per 10 3 1/2 2S/2D $24.95 per 1O 31/2 2S/HD $49.95 per 10 $166.80 Gender Changers 25pin i!:lmale to Female or Male to Male Rigid $12.95 Flexible $12.95 9pin Female to Female or Male to Male. Rigid $7.95 C.ntron/cs 36pin Female to Female or Male to Male $16.95 ffl.00 Ethernet Cab1es ~ od tq6 e 3 1/2 digit plus 41 segment analog bar graph e Autoranging or manual selection 6 functions• Vdc. Vac, Ade. Aac, Ohms, Diode Water resistant e Data hold • Memory offset Ranqss Vdc 200mV. 2V, 20V. 20CN. 1000V Vac 200mv. "N, 2rN, 2ooy,J_SrN Ade 20011A. 2mA. 20mA. ,w:nA_ 2A, 20A. Aac 200uA. 2mA. 20mA. 200mA, 2A, 20A Ohms 200!1, 2k{l 20k{l 200kn, 2Mn, 20Mn We have 2 wide range at prices to suit any budget, incfuding ~rofessional"ComTest models. ri~1E~f ly We are stocking the UPS501 which will provide up lo 7 minutes battery supply for a SOON load. This gives you ample time to power down your system in the event of a mains failure. Instant switch-over. Battery ~~~~:ri~J~~~i~fi);~ed. ~!~i~~8 Allow $20 P&P ($680.00 ex tax) Six models to choose from "O"Ty,,. 9 pin 2 wey 25pin 2way .00 25ptn 3wey .DO 25pin 2wey automatic .OD Centron/cs 36pln 2wey $45 .DO 36pin 3wey $65.00 Also°!tailable with transistor tester in place of capacitance ran_ges. (Model 93T) $1k80 $99.95 '~ 0 • 1999 count • Large 20mm high contrast LCD readout • BFunctions• Vdc. Vac, Ade, Aoc, Ohms, Diode, Frequency, Capacitance e 0.5% de accuracy ·o' indicate standard activities. 2 spare LEDs for miscellaneous lines. 24 DIP switches for configuration. Patch into any of the 2~ active lines ~ G Modo/93 In Un• 025 Patch Box Quick and simple to wire internal pcb pads connected to pins on connectors. Solder leads provided to make up any configuration. $16.95 c~n\~~~~-~i~~i~!~~~ tf8~n "D" Save Problems and Cos ~ and UL1244 standanlr larra/1 Of/Bratian 1~~ 8:!ls 0 I.I.. Cl 0 ::r::m~Y'4i?t~--:S~, Flat Ribbon Cables 025 Male & Female to D25 Male/ Female. Yes both sexes each end! 0 rnhcoo~~g~~~;c~g~~l~J~~ower. male to male, fem!:t,DO Arrestor tor maximum protection. female or male to female. Fully 2m Cables $19.95 ._ _approved. _ _ _ _ _ _$64.95 ___, All SCSI checks for proper earJ:ing etc. us Modular type plugs and sockets for 3112" or 5114" er: 9aand 98 hav, ana/lJfl bar • &Jfu~s:3,d Input tannlnalr and function switch /or ,asy 111/t/tig • Pro/la 11Dra,1 c//fll built In for ,asy_ two handad m,asu,.m,ntr • 11111 96 is wat,r /Wslslanc, far Industrial us, • Shackpraal /or a drop of 1.5ml • Built-In till s/and Ran11u Disk Cleaners ~ Look at lhl llahl/81• Laro, hiah contrast display • Th, Min/Tester 7 dual colour LEDs monitor TD, RD, RTS CTS. CD. DSR & DTR. 25pin plug and socket $24.95 In Un• 025 Wiring Box ~:\~~I~ above but with spring Tinned leads supplied $25.95 9pin male to 25pin female rigid $10.50 9pin female to 25pln male rigid $10.50 9pln female to 25pln male 2m long cable $19.95 ~ $12.95 $11.95 ln-Une Switch Box Handy for reconfiguring cables. 25pin plug and socl<et $14.15 :~fJ~1W:. 881~ ~ Why pay up to $150 for a label? Take a close look al APPA muttimeters. Look familiar? That's because they're sold under different brand names. And that means you could pey a lot more than you need to. We've seen the top of the tine model selling at around $150 more than our price. So you·re peying that much extra just for the brand label! ClJ,F $214.80 Model 76 C""'pon•nt Te t•r Does the things your multimeter doesn't! • Capacitance 200pF to 20uF • Resistance 2000 to 20M'n • Transistor hie and lceo • Diode displays VI at 1mA e LED dls~;r; VI al 2Ma and 10mA = ~ierass~ai~:rd 1.SVcells If you can't find what you want, n'// make It for you/ Our servlcll now Includes • •o· type connect"'• with eh/aided cable • 1oc types onto flat cable • BNC ty,,.s onto coax. C1111 ·us for II quote! $142.80 LEC R0NICS PTY LTD 229 Burns Bay Road, (Corner Beatrice St.) iNc IN Nsw Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N.S.W. 2066 Telephone: (02) 428 4111 Fax: (02) 428 5198. 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday. Mail Orders add $5.00 to cover postal charges. Next day delivery in Sydney add $5.00. All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. ~!!!f!!:=:'.~....--~-__,. ► ~ !. 10 au~ BANKCARD, MASTERCARD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED -~0 c:, .,, o. ::0 2 ~ AMATEUR RADIO BY GARRY CRATT, VK2YBX How quartz crystals work One of the most common components encountered in amateur radio, yet possibly the least understood, is the quartz crystal. This article sets out to explain some of the mysteries behind the quartz crystal. Quartz is a piezoelectric material. Piezoelectricity is literally "pressure electricity", the prefix piezo being derived from the Greek "to press". The direct piezoelectric effect was discovered in 1880 by the Curie brothers and refers to the electric polarisation of these materials brought about by applying mechanical strain. Conversely, piezoelectric materials can be deformed by applying voltage to them. Many different substances have been investigated as possible piezoelectric resonators. Compared to other resonators - eg, LC circuits, mechanical resonators such as tuning forks, and piezoelectric resonators based on ceramics or other single crystal mat- erials - the quartz resonator has a unique combination of properties. The material properties of single crystal quartz are both extremely stable and highly repeatable from one specimen to another. The acoustic loss or internal friction of quartz is particularly low, leading to one of the key properties of a quartz resonator: its extremely high Q factor. The intrinsic Q of quartz is around 107 at 1MHz. Quartz crystals typically have Q factors ranging fro~ tens of thousands, to hundreds of thousands; ie, thousands of times better than the best LC circuits. Because of their inherently high Q, quartz crystals are also very stable. Quartz is a crystalline form of silicon dioxide, SiOz·. It is a hard, brittle, transparent material, with a density of 2649kg/m3 and a melting point of 1750dC. Quartz is insoluble in ordinary acids but soluble in hydrofluoric acid and in hot alkalis. Despite the natural abundance of quartz (sand is largely made up of grains of quartz), it is surprising that quartz crystals of sufficient size and purity for processing are very rare. Cultured quartz For all but exceptional requirements, natural quartz has now been superseded by cultured quartz for the manufacture of resonators. Cultured quartz is now routinely grown from aqueous alkaline solution, under conditions of high pressure and temperature in massive underground steel autoclaves. The lower part of the auto- z y -10 A, B, C constant T : Temp, Fig.1: this diagram shows how the various blanks may be cut from a quartz crystal. The AT cut is the most common but other cuts can also be used, depending on the characteristics required for the cystal. 66 SILICON CHIP To : Reference Temp. Fig.2: temperature vs frequency characteristics for various cystal cuts. As can be seen, the AT cut is the most stable. +18 ABCDE F J GH K +60 +50 L FREQ. +40 CHANGE PPM +30 M +20 N 0 -10 - 20 0 - 30 - 40 -50 -60 - 54 -44 -34 -24 - 14 -4 +6 +16 +26 +36 +46 +56 +66 +76 +86 +96 +106 +116 +126 +136 TEMPERATURE °C Fig.3: the temperature performance of a quartz crystal is governed by the angle at which the blank is cut from the crystal. These "S" curves show the expected frequency vs temperature variation for AT cut crystals. clave is maintained at a temperature of about 400°C and contains nutrient in the form of pure silica. At this temperature and at pressures in the order of a thousand atmospheres, the solubility of silica is relatively high and a saturated solution is formed. Convection currents transport the saturated solution to the upper part of the autoclave, which is maintained at a slightly lower temperature-of aociut 350°C. At this lower temperature, the solution is supersaturated and the quartz is deposited on seed crystals suspended in the cooler region of the autoclave. Over periods of many days or weeks, crystals of substantial size can be grown for use in the manufacture of resonators. By slicing the raw crystal at various angles with respect to its axis, it is possible to obtain a variety of blanks having different vibration modes and different temperature characteristics. The most commonly used type of resonator is the "AT" cut, where the quartz blank is in the form of a thin plate cut at an angle of about 35 degrees to the optic axis of the crystal. The AT cut has a frequency/temperature coefficient which can be precisely controlled by small variations in the angle of the cut. Various cuts Fig.1 shows how various blanks are cut from a quartz crystal, while Fig.2 · shows the variation of temperature/ frequency characteristics of various cuts. As you might expect, the performance of a quartz crystal over a temperature range is governed by the angle at which the blank is cut versus the axis of the quartz. The "S" curves shown in Fig.3 form a useful guide to the expected variation of frequency versus temperature for the commonly usEd "AT" cut. For crystals falling in the range 1MHz to 150MHz, a frequency tolerance of ±0.0005% over a temperature range of-55 to +105°C is readily achievable. The final essential characteristic of the quartz resonator is related to the stability of its mechanical properties. Short and long term frequency drifts of only a few parts per million per year are readily available from commercial units. The highest degree of "ageing" occurs in the first week after manufacture. After this time, the ageing process decreases logarithmically. Precision crystal units manufactured under closely controlled conditions are second only to atomic standards in their frequency stability. The first step in manufacturing a crystal resonator involves processes similar to those involved in the manufacture of optical lenses. Initially, the crystal "bar" is oriented using x-ray diffraction techniques, to determine the precise angle at which the blank must be cut. The crystal bar is then cut into wafers by a precision sawing machine, using a lapping technique, where the bar of quartz is cut by a series of steel blades driven in a reciprocating motion, while being continuously flooded with an oil based slurry. After the wafers have been sawn from the quartz bar, they are lapped JANUARY 1991 67 Co ---,I .---------i - ( ~~ c, R, L, Fig.4: the crystal equivalent circuit. Co represents the static (shunt) capacitance & is the sum of the capacitance between the electrodes plus that added by the wire leads & holder. The Rl, Ll, Cl branch is · known as the "motional arm" (see text). and polished, as any irregularities in the surface of the wafer must be reduced to a small fraction of a wavelength to keep losses to a minimum. The thickness of a typical AT blank can range from 2mm down to 33µm , with the required tolerance being 0 .1 % , so a high degree of polishing is necessary, just like an optical lens. After the mechanical processes are complete, the blank must be carefully cleaned. This is achieved by a combination of ultrasonic washing, rinsing in de-ionised water, etching in ammonium biflouride solution, then radiating the blank with ultraviolet light in the presence of oxygen. This final process is known as UV-ozone cleaning, as ozone is produced by the action of ultraviolet light on oxygen. trade is defined by using photo-etched plating masks. The electrodes are normally made from gold, silver, or aluminium, and this material is deposited using an evaporation technique. The crystal is now ready to be mounted. There are several methods of mounting the crystal which allow good electrical connection, as well as adequate mechanical support. The most commonly encountered system is the "spring mount", which uses two gold plated springs similar in appearance to a watch hairspring, which hold the blank at the electrical connection points. These springs are secured with a small amount of silver loaded epoxy resin, which is applied by a syringe. After the cleaning stage, the blank frequency is typically left 1 % higher than the desired frequency, which is compensated for by the loading effect of the electrodes. After mounting, the crystal will typically be within ±0.2% of the desired frequency. The final adjustment can be made either by plating additional electrode material onto the blank in order to bring the frequency down or by etching away some of the previously deposited electrode material, in order to take the frequency higher. Other more complex mechanical systems have also been developed for mass production. The equivalent circuit of a crystal, shown in Fig.4, can be used to explain the basic concepts governing the performance. "Co" represents the static (shunt) capacitance and is the total of the capacitance between the electrodes and the capacitance added by the wire leads and the holder. The Rl, Ll, Cl branch is known as the "motional arm". Cl represents the "motional capacitance", or the elasticity of the quartz. L1, the "motional inductance", corresponds to the oscillating mass of the quartz, and Rl is the sum of the bulk crystal losses. The values of "motional capacitance" are very small compared to the values of capacitance normally used in oscillator circuits in amateur radio, and can be calculated for the "AT" cut as follows: Cl (pF) = 0.22 x Ax F/1670 where A = the area of the electrode in square metres and F = the resonant frequency (Hz). The value of Cl can be changed for a particular resonant frequency, by varying the electrode area. This, in turn , is determined by the diameter of the quartz element. For AT cut crystals, this value is normally 10 to 30 femtofarads. The static parallel capacitance, Co, is the capacitance between the vacuum deposited metal electrodes and the quartz material as a dielectric. The Attaching electrodes At this stage the blank is ready for the attachment of electrodes. This is done using vacuum deposition techniques, where the shape of the elec- +iX I I f, ~Dr-° lp -iX f o-!HOf-o +;X ~ +jx I : fp CL / I -jX - jx i Fig. 2 fs: f p: Series Resonance anti Resonance t 0i;x , / v' fL ~ ,I / I I I CL < Fig.5: the impedance graph for a quartz crystal. There are two resonant frequencies: the series resonant frequency fs at impedance = 0 & the parallel resonant frequency fp at impedance = =. 68 SILICON CHIP Fig.6: the quartz crystal may be connected.in either series resonant mode (centre) or parallel resonant mode (bottom). In practice, the capacitor (CL) is used for fine adjustment of the crystal frequency. Fundamental Mode Oscillator 15 E 0. 10 0. ~ 5 --- •-10MH,: "I 0 I0~ 20MH1 -5 'C1: 560PF C1, JOO pF C,; 270pF C1; C 1' 1 C.~ -10 ,1 C,+C2 + 5 (pF) - --·-+ -- C, +C, C, C2 CJ<<C2 -15 0.1 0.01 1 10 lOOrnw Overtone Mode Oscillator 1 Nq--~ Fig. 7: the effect of high drive level on the resonant frequency of a crystal. The resonant frequency changes prior to destruction due to heating of the quartz. f, value of Co and Ll are as follows: Co(pF) = 40.4 x Ax F/1670 + 0.8pF For typical AT crystals, this value ranges from 1-7pF. Ll(H) = 4.22 x 104 x (1670)3/[P x A] Fig.5 shows the impedance graph for a typical quartz crystal. Neglecting losses, two resonant frequencies result, namely the series resonant frequency (Fs) at impedance = 0, and the parallel resonant frequency (Fp) at impedance = infinity. The mathematical formulae for calculating those two resonant frequencies are as follows: Fs = 1/21t✓L1.C1 = 1/21t✓L1.C1.Co/(C1 + Co) The parallel and series resonant frequencies are related by the equation: Fp = Fs✓ l + Cl/Co and the relative frequency interval between the two resonant points is equal to half of the ratio of Cl to Co, as shown by the equation: (Fp - Fs)/f = C1/2Co By series connection of a load capacitor with the crystal, the series resonance mode occurs. By connecting the capacitor across the crystal, the parallel resonance mode occurs. = 2 ir ✓ L,C, ex . Fig.6 shows the result from the connection of either a series or parallel capacitor. In practice, this capacitor is used to provide a means of adjusting the crystal frequency. It can either be a fixed capacitor, with or without a trimmer, for fine frequency adjustment. One of the important points when using a crystal oscillator is the amount of drive signal applied across the crystal itself. The amplitude of the mechanical vibrations of the crystal is proportional to the amplitude of the current flowing through it. If sufficiently high current is allowed to flow, the tensile strength of the quartz will be exceeded, causing it to fail. Fig. 7 shows how, just prior to destruction, the resonant frequency of the crystal changes due to heating of the quartz. Suffice to say, the drive level (normally expressed in milliwatts) should be kept to the minimum necessary to ensure stable oscillation. Excessive drive can result in excessive frequency drift and poor ageing. Typical levels used with AT cut crystals are in the order of 1-ZmW. Crystals are made in a large variety of shapes and sizes, depending upon the application. To meet these applications, a range of standard case sizes has been developed. Each case houses a crystal of a particular blank size, which then determines the lower end < f. ' CJ< <C. f0 ;47MHz C,; 150pF C,; 1 00pF C3; 5pF L,; 0,56µ H L,; NON L, Fig.8 (right): typical circuits for fundfamental & overtone crystal oscillators. In overtone operation, the crystal is made to oscillate at an odd harmonic (3rd, 5th, 7th etc). Fp ~ C .1 6 MHz JOpF J. 6 - 20 MHi 20 pF 150 pF C,; C,; 1 0pF 20pF of the frequency range for each type. The cases are sealed using .the resistance welding technique which has replaced the earlier solder seal and cold weld methods. While a discussion on the merits of various oscillator circuits is beyond the scope of this article, we will just briefly mention the two modes of oscillation, fundamental and overtone. Fundamental operation is self explanatory - the crystal is made to oscillate at its fundamental frequency. In overtone operation (3rd, 5th, 7th), the crystal is driven to oscillate at the overtone frequency, while still within the drive limitations previously mentioned. Either series or parallel resonance modes can be used for fundamental or overtone crystals, but a crystal designed for fundamental operation cannot be used sucessfully for overtone operation. Fig.8 shows circuits for fundamental and overtone operation. References (1). Hy-QHandbook of Quartz Crystal Devices by David Salt, 1987. (2). Kookje Electrical Industrial Co Ltd, Korea - data sheets. (3). Harmony Electronics Corp., Taiwan - data sheets and catalog. (4). Ilshin Communication Co Ltd Korea - data sheets and catalog. (5). Hy-Q Crystals Pty Ltd - Quartz Crystal Product Guide. SC JANUARY1991 69 1-9 ..... 10+ 31 /2"OD $19.95 $18.95 31 /2"HD $39.95 $37.95 31/2"HD $45.95 $42.95 51 /4"OD $8.95 51/4"OD $14.95 $12.95 51 /4"HD $19.95 $17.95 5 1 /2"HD $23.95 $22.95 $9.95 DYSAN VERBATIM 1-9 .._ 10+ 31 /2"OD $22.95 $21.95 1-9 ..... 10+ 31/2"OD $29.95 $27.95 1-9 ..... 10+ 3 1/2"OD $28.50 $27.95 31 /2'"HD $39.95 $37.95 3 1/2'"HD $49.95 $47.95 31/2"HD $53.50$52.50 3 1/2"HD $69.95 $67.95 51 /4'"OD $19.95 $18.95 51/4'"OD $19.95 $17.95 51/4"OD $22.95$21.95 5 1/4'"OD $19.95 $18.95 51 /4'"HD $31.95 $29.95 5 1/4"HD $29.95 $27.95 5 1/4"HD $24.95 $23.9 ALL PRICES PER PKT/BOX OF TEN 5 1/4'"HD $39.95 $37.95 SERVICEMAN'S LOG All the IDakings of a Chinese puzzle Servicing often involves more than electronic expertise, experience and a set of service manuals. Knowing what to expect in particular sets often means knowing something of the manufacturer's history and even, as in this case, where the set was made. This was brought home quite forcibly by a recent experience with two TV sets, supposedly identical but actually as different as chalk from cheese. Both were 36cm GC-149 colour sets, made under the General label. Now the General label has had a somewhat chequered history. Originally a modest-size Japanese company in its own right, its sets were very popular and they appeared on the Australian market with the introduction of colour TV. More recently - about five years ago - the company was taken over by Fujitsu and many models are now sold under the Fujitsu General label. On the other hand, and rather strangely, some still carry the simple General label. (The company is represented in Australia by General Corporation Australia Pty Ltd , 10-16 South St, Rydalmere, NSW 2116). Routine but interesting The first set did not present any complex problems and was fairly routine in fact. But it was interesting in other ways. It was a faily new set, only some six months old and still under warranty, and was owned by one of my long-standing customers. More importantly, in this context, he is one of those loyal customers who would never consider taking a set to anyone else. The complaint was straightforward enough: sound and raster, but no picture. I pulled the back off the cabinet and this gave good access to several 72 SILICON CHIP useful check points. These included the R,G,B stages and I checked the voltages on the relevant transistor collectors. These all came up very close to the 123V shown on the circuit. I checked these same points with the CRO and wasn't particularly surprised to find no signal. Nor was there any signal on the bases of these stages. Again, no great surprise. From here I jumped back to the luminance circuit and, specifically, to the video drive stage, Q201 (2SA733AP), which is fed from pin 48 o( the jungle IC, IC201 (UPC1420CA) - see Fig.1. An output is taken from the emitter of this stage but there was no luminance signal at TETIA TV TIP Rank C-1851 Symptom: weak sync. Flagwav• ing at top of picture on reception of TV channels, total breakup of picture when viewing video recordings. Cure: C556 (10µF 16V electro) dried out. This capacitor passes pulses from the AFC pulse amp (TR505) to the flywheel discriminator ahead of the line oscillator. TET/A TV Tip is supplied by the Tasmanian branch of The Electronic Technicians' Institute of Australia. Contact Jim Lawler. 16 Adina St. Geifston Bay, Tasmania 7015. this point. Nor was there any at the base, which couples to pin 48. Back tracking from here took me to transistor Q3, the first video amplifier. There was luminance signal at the base of this stage, and also at the emitter, from whence the signal goes to pin 42 of the IC. So yVe had signal into the IC but no signal out. Before jumping to conclusions, I checked the voltages on the IC pins. These voltages did not tally exactly with those on the circuit they seldom do - but there were no gross abnormalities, and I felt my original suspicion was justified; the IC was crook. I didn't have a replacement and it is a type I don't normally stock. The failure rate is low and it would be stock lying idle. Nor was I keen on buying a replacement since, under warranty, I would not be reimbursed financially but only with a replacement device - which I might not use for years. So the plan was to remove the suspect unit and return it to the local company for direct replacement. A real mess It was only then that I removed the main board and turned it over to attack the IC connections. And what a sight met my gaze. If I hadn't known . the set's history and the honesty of the owner, I would have assumed that some striped apron merchant had been at it with his traditional tools of trade. Not to put too fine a point on it, it was a right proper mess. And since I did know its history, it was obvious that this was the way it had come from the factory. Now it is not unusual to find, in any new set, that there has been some additional work done in the factory. As sets come off the production line and are given a preliminary test, there will inevitably be a small proportion that don't work. · These will be diverted to a production service bay, the faulty compo- 3 /l4BLII C15 NA TERM! NAL o.o, ·o Cl 51 1------1 CHROMA PROCESSOR VIDEO AMP SYNC AMP.VERT OSC.HOR.OSC IC201 UPC1420CA R.l06 s.&< C31 \ \!S(]P C3\2 \!S(]P C3\3 1110P n~ ~~,...~-it-.-_-_-_-r--.-v-------i~---0-~ . Fig.I: relevant portion of the General GC-149 circuit. The jungle chip is at the bottom, the video driver stage (Q201) at left above it, and the 1st video amplifier transistor (Q3) at top centre. The problem turned out to be simple enough, although the PC board on which the parts were mounted was a real mess. nent or connection tracked down and replaced or repaired, and the set returned to the testing line. And one can usually spot such work; a hand soldered connection will leave a ring of rosin flux - something which doesn't happen with the flow soldering process. Nor is there any objection to this procedure. After all, it would be stupid to discard a whole board, simply because one minor component was faulty. But there was nothing minor about what had happened to this board. For starters, cuts and scratches had been made in the board between most of the pins of the IC in question, and pretty roughly at that. The green varnish which normally covers the board had been scraped and cut, and some of the cuts were quite deep. But it wasn't only around the IC. There were quite a number of cuts at odd random spots on the rest of the board. The meaning of life What did it all mean? Was I wrong in my diagnosis of a faulty IC? Was there some more subtle fault, possibly intermittent, which had eluded the factory tests and was now in my court? JANUARY 1991 73 arrived and was fitted. And that was it, the set worked first time and turned in a first class performance. Beauty really is only skin deep! So the set was duly returned to the customer, who was delighted with the performance. But he was quite shocked to learn that it had been made in China, rather than Japan, where he imagined it had been made. Truth to tell, I doubt if he would have bought it had he known. On the other hand, there was no point in worrying him unnecessarily - the set could go for years and never miss a beat. So I kept my findings and impressions to myself, simply answering his inevitable question with the truth; it was a faulty IC. SERVICEMAN'S LOG - CTD Perish the thought! In any case, the IC would have to come out and be replaced. If my worst fears were realised, someone else, like the local General Corporation, could take on the job. But the whole situation alerted me to something I had overlooked up until this point. The set had not been made in Japan - they would never allow a set like this to reach the market. Nor had it been made in Korea, where the quality control, while not quite as good as that in Japan, would never pass anything like this. No, the fine print on the spec. plate indicated that this set had been made in The People's Republic of China. This was the first time I had encountered anything from this region and, superficially at least, it appeared to be exactly the same as the versions made in Japan - even down to the components used. A grotty effort There was only one exception; the printed circuit board. Forced to look at it closely I realised that it was a pretty grotty effort, with very rough edges and dags on the copper tracks. While the other major components had obviously been imported, I tip that the board had been made in China. And this, I suspect, was the reason for all the cuts and scratches; the rough copper pattern had resulted in bridges between tracks, preventing the set from working in the first place. There may have been only one or two such bridges, but the technician had adopted a blanket approach, cutting and scratching between all suspect tracks until the set came good. This, in turn, suggested a fairly low level of service expertise, low labour cost, and a situation where time was of little consequence. And in support of that last point I would judge that several hours had been spent working on that board; a lot longer than would be tolerated in most factories. Nor was this service confined to cuts between tracks; closer investigation revealed that several copper tracks had been cut and subsequently bridged. Obviously another blind approach to solving the problem. And in a couple of cases, the tracks haq. been cut and left cut; apparently part of some modification process which must have been legitimate, because the set had ·worked (and eventually worked again). Anyway, there was little I could do about that; time did not permit a detailed analysis of situation. I simply pulled the IC out and sent it back to the company for replacement. Then I went over the board and did my best to clean it up. There wasn't a great deal I could do but it did look a little better when I'd finished. Granted, it wouldn't make the set perform any better, but it did give me some satisfaction. In due course, the replacement IC Dropped General And that brings me to the second version of this set. In fact, it came into the workshop while I was still working on the first one. The owner is another regular customer and he was somewhat agitated. He was leaving on an extended caravan holiday the following day and was loading the set into the van when he dropped it. Now it didn't go! Could I have a look at it and perhaps do an emergency repair? Surprisingly, there wasn't a mark on the cabinet even though, by all accounts, it had taken a pretty hard knock. But one glance inside told the whole story and points up what I consider is a serious weakness in many sets on the market today. The main board sits in the bottom of the cabinet, supported by its right and left hand edges, which slide into 0 ••• ~-r TM~ TV , 1'HE 'PEOPLES 'RePUSt.-1C OF ClilN~ •• 74 SILICON CHIP slots moulded in the cabinet. And that's all the support there is. When it receives a jolt, even a relatively mild one, the weight of the horizontal output transformer is just too much, and the board cracks. That was exactly what had happened in this case, which didn't really surprise me. In fact, I already had an AWA Mitsubishi in the workshop which had suffered the same fate. Again, there was no damage to the cabinet and, as far as I could determine, the drop had been quite moderate. Nevertheless, the board had cracked under the horizontal transformer, severing about 10 tracks in the process. But that's another story. The damage to the General was more severe. It had cracked roughly diagonally across the rear right hand corner, under the transformer. Fortunately, it had not cracked right across, so there was still some mechanical support. I went over it with a glass and, at a rough count, there were 37 broken tracks. And those were only the ones I could be sure of. I shook my head; even assuming that I could find time to do the job in the few hours available, there was no way that I could guarantee it, with the set being jolted around in a van. To have any chance of a permanent cure I would need to run it on the bench for a substantial period, give it a good shaking from time to time and, ideally, subject it to a range of temperatures. And even then, we'd both have to accept that it might bounce after several months. But a quick fix for use in a van? No way. When I made these points to the owner, he accepted the situation philosophically. "I'll go out and buy another portable. You hang on to that one and see what you can do with it while I'm away. See ya in a few months". Easier than I thought And so the set was pushed into a corner until such time as things were slack; an ideal way to tackle a job like this. In fact, the repairs to the board took less time than I had anticipated and went without any problems. But I couldn't help noticing the difference between this board and the previous one. Both sets were made in China but this one was as neat and well made as any I have seen. Is Your Product Or Service Getting The Exposure It Deserves? 25,000 consumers will read this page. They need to see your advertisement if you want them to buy your product. Contact Paul (018) 28 5532 or Ian (03) 696 5411 to reserve this space. So I pass. More to the point, the set functioned at first switch-on, which was more than I had hoped for. Unfortunately, after my initial elation, I realised that all was not perfect. It was exhibiting more than normal purity error in the top left corner (bluish) and about halfway down the right hand side (magenta). Apparently, the fall had moved or distorted the shadow mask slightly, and there is little that one can do about that, at least directly. The real solution would be a new tube but the cost would be hard to justify. The best I could do was give it a purity adjustment and hope that I might score some improvement. So I slackened off the yoke retaining screw, and juggled the assembly for the best result. I didn't score a great deal but any improvement was worthwhile. Then I re-converged it and this came up very well. So the final result was usable even if something less than perfect. To tell the truth, I imagine most viewers would probably be unaware of the fault unless their attention was drawn to it. And there this job rests, still in the workshop, waiting for the owner to TV TEST EQUIPMENT THAT WILL EARN YOU MORE MONEY (AUSTRALIAN MADE) 12 Months Warranty SHORTED TURNS TESTER Built-in Meter to check EHT transformers including split diode type, yokes and drive transformers . $78.00 + $3.00 p&p HI-VOLTAGE PROBE Built-in meter reads positive or negative 0- S0kV. For checking EHT and focus as well as any other Hi-tension voltages. $98.00 + $5.00 p&p LOW VOLTAGE PROBE Ideal for checking microwave ovens and TVs. The ranges are from 0 to SkV Negative and from 0 to 10kV Positive. Double insulated for safety. $84.00 + $5.00 p&p &p . $75. • ,.... DEGAUSSING WAND 7,700 apere turns. Strong magnetic field, larger than usual coil with multicore centre. Double insulated for safety with momentary on/off switch. 240V NG 2.2 amps. This one is just about as impot1ant as having a soldering iron in your toolbox! ... ..,. <REMOTE CONTROL TESTER . (INFARED OR ULTRASONIC) $85.00 + $4.00 p&p TUNER REPAIRS TV . Designed to test any lnfared or Ultrasonic control units. With the extension lead you can also test infared units which cannot be placed in front of the testing unit. Requires a 9V battery . Output is via the LED diode and piezo speaker. trom only . we also repair most tuners on an exchange basis. "• • s11.oo + p&p Cheque Money Order Bankca;d or Masterca~d 11JNER51\216 Canterbury Road, Revesby, ~ NSW, 2212, Australia Telephone (02) 774 1154 JANUARY 1991 75 ~ ~~~<at> o• ~ t·~~/J ' ; l f ~?~ ~ ~ - ( ~ ~~~~~:::~ ~~ 14 I .) ' ' iE r al l llh I' return from holidays. I hope he won't be too disappointed. But the moral is obvious; TV sets don't like being dropped. The ghostly antenna And now, for a change of scene, here's a funny one from my southern correspondent, J. L. of Tasmania. And when I say "funny" , it was more "funny peculiar" than "funny ha ha". Here's how he tells it. This is a tale about a ghostly car radio installation. It comes from a colleague who runs a small business specialising in mobile communications. To appreciate the story, it is 76 SILICON CHIP first necessary to understand how an automatic radio antenna works. These systems usually have two leads (plus an earth) attached to the antenna actuating motor. One is a permanent connection to the 12V supply while the other is a control line and is usually connected to a switched 12V output from the radio. This operates a DPDT relay to control the direction of current flow through the motor. When the control line is low (ie, at 0V), the relay connects the antenna motor in the "down" configuration and the antenna retracts until, in the fully retracted position, a limit switch is activated. Conversely, when the control line is energised, the relay switches the motor to the "up" configuration and the antenna extends until, at full height, another limit switch is activated (see SILICON CHIP, March 1990, page 30, for additional details), In the ideal case, the control line is connected to the switched 12V output on the radio. This is energised when the radio is switched on, thus causing the motor to run forward and raise the antenna. If the radio has no such outlet, an alternative approach is to connect the control line to the accessory position on the ignition switch. In this case, the antenna will be raised whenever the ignition switch is in the running or accessory position, and will be retracted when the ignition is turned off. Now to the story. It seems that a new radio had just been fitted to a vehicle, along with an automatic antenna, when the customer arrived to take delivery. The last connections to the antenna control circuit were still to be made and the installer was working against time. And, since this radio did not have an automatic antenna power outlet, the control line had to be connected to the accessories terminal of the ignition switch. The installer turned on the ignition and searched for an active 12V line. He found one and connected the control line to it. The antenna worked perfectly, and so did the radio - for about three days. Then the owner found that whenever he turned sharply left the antenna retracted, then went up again as he straightened up. The same thing happened when he accelerated - the antenna would retract and then shoot up again as he eased off the pedal. It reached the point where, in stop-start traffic, the antenna was continually winding itself up and down, which made reception virtually impossible. This pattern continued for a couple of days then cleared up, only to show up again later in the week. The owner wasn't too happy about it and brought the car back to have the antenna system checked. Just fill 'er up This time it was examined by a technician, rather than the installer, ·and he found a most bizarre reason for the problem. The 12V control line had not been connected to the accesories side of the ignition switch, as intended, but to the petrol gauge line. At the time the installation was done this line measured 12V, but this value was fated to vary as the fuel level dropped. With a full tank the system worked normally but, as the level dropped, the fuel sloshing about put lower and varying - voltages on the antenna control line, which eventually dropped below the hold-in level of the relay. Hence the mysterious effect. In fact, if the tank had been taken down to nearly empty the antenna would not have worked at all. The symptoms cleared each time the tank was filled but, in between, the owner thought his car was haunted! Which just goes to show that it doesn't pay to rush any job that even remotely involves electrical connections. Serviceman's boo-boos Thank you J. L. That's a new one on me. Very early in my career I earned HAUN"i'E.D( NO StR; '(OUR CAR IS ~ST E.X_C-1 i""E:-D :I my bread and dripping fitting car radios to the then popular vehicles like the Austin A40 and the first Holden. And we had our fair share of boo-boos. I once witnessed an incorrect connection behind the dash destroy a whole wiring loom on a brand new car. What the boss said to the hapless perpetrator doesn't bear repeating. At a personal level, the worst experience was more painful than anything. Groping behind the dash for a connection I managed to bridge an active terminal to chassis via the metal strap on my wristwatch. Almost before the pain registered it had melted two links out of the strap, and left their imprint burned into my wrist. The scar has now faded but was visible for several years. But patching into the petrol gauge no, we never did anything like that; that takes the prize. Correspondence And finally, I feel bound to reply to a reader, R.W.H. of TasmanJa, who has written to the editor, questioning some points raised in my October notes. His letter was reproduced on the Mailbag page of the November issue, together with a brief editorial comment. I refer readers to this for the full text. As far as the transformer is concerned, there is little that I can add to the editorial comment; my sentiments entirely. However, the transformer in question is sitting on my desk as I w:&ite and, if R.W.H. would like to conduct his own research, he can have it for the price of postage and packing! And the supposed excessive charges? Nowhere in my notes did I state that the customer was charged for the replaced driver transistor, Q501. Experimental replacement of minor components like this are a normal part of everyday sevicing. If it cures the fault, well and good; if it doesn't, one writes it off as a few cents - or even dollars, sometimes well spent. And it is a lot cheaper than wasting hours using alternative approaches. In fact, all the customer was charged for was the transformer and the output transistor, Q551. And, yes, the customer was told to " ... bring the set in right away"; and he agreed to do that. I rest my case. SC PHONE LINE AND MAINS FILTER/SURGE PROTECTOR Protection tor swering machines rdless phones csimiles The Arista model CPEP-1 ensures that lightning, power surges and spikes do not reach your costly communication equipment as it constantly monitors the PHONE line and the MAINS power line. Simply connect to any existing power point, plug in your tax, phone, video, Hi Fi or any other 240 VAC operated equipment and a series of indicators shows the status of the mains power point while several MOV's and gas arrestors prevents access to damaging energy sources. 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If you already have a subscription we will be happy to supply it to a friend, you nominate, with your compliments. 500 95mm x 3mm Cable Ties $30.00 Bonus Subscription ~ Your Price $30.00 500 190 x 5mm Cable Ties $65.00 Bonus Subscription ~ Your Price $30.00 PHONE TODAY FOR THIS LIMITED OFFER SOUND AUSTRALIA 28 Walker St. Dandenong, VIC, 3175 Telephone: (03) 7911622 JANUARY 1991 77 CITIZEN CX-70 PRINTING CALCULATOR A-3000 REMOTE CONTROL SYSTEM "You can c9ntrol just about anything with this remote control transmitter/receiver. TVs, Stereos, Alarms etc. * Rea:!iver relay output: N.OJN.C. up to 5 afl'lE. * Rea:!iver operating voltage: 12 'AJlts DC * Complete with two (2) remote keys (batteries included) * * 10 Digit LCD display * Memory Function * % mark up / Mark down * Date Function Q)erating Distance: 10 meters * Frequercy: 300- 310 MHz * Accepts standard paper (58mm) Battery or mains adaptor operated (not included) NORMALLY $109.95 * ·. 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Each input has its own separate audio volume control for fading musk: etc. in and out as well as a master control for attenuating the overall audio output level. SPECIFICATIONS uto and Manual range operation. Miclnput?: 1 x 6.5mm socket arrpere mea5UrE!ll1el7I Line Inputs: 3 x RCA sockets Output Imped: 300mV <at>600 OHM ictestfundion (CMOS'TTL) Signal to Noise: 55dB hold and diode test functions. Frequency Resp: 20Hz to 20KHz +i-2dB 300mV Output Level: continuity bJzzer. 0VDC 006P Battery Power Sup~y: ooc NOW ONLY $55.00 igit LCD display. Convert your Oscilloscope to a Spectrum Monitor with a Bandwidth of 100mHz 1CH. OSCILLOSCOPE * * Sensitivity: SmV/DIV to SV/DIV, DC to 10MHz. * Timebase: 1Oms/DIV to O.1us/DIV. * Includes probe. * 12 months Warranty. The SPECTRUM PROBE is a low cost 100mHz Spectrum Analyzer in a handheld probe. * Now see the frequency oomponents of signals and noise. * Use it a5 a sensitive RF detector. • Locate radiated EMI sources. ' ' * Check your RF signal generator. * Check for stage gains in amplifiers. Model: VOS 107 ( As Featured in Silicon Chip Nov. '90) MALLY $499.00 ONLY$395.00 .00 PLAYMASTER "PRO SERIES ONE" HIGH POWER AMPLIFIER KIT NORMALLY $599.00 NOW$549.00 SAVE$50.00 Watts RMS into Bohm 4ohm at 1OOWatts into Bohm . 100kHz Sweep Modes: Auto, Normal. * Display: X-Y operation. KASPAROV - "CONQUISTADOR" 16K CHESS COMPUTER * 17 Playing Levels * 4 toumment Levels with clock controlled play * 3 Specialist Levels (Problem Solving, Infinite, Analysis and 10 second d1ess) * 9 Casual Levels 0ncluding MAKES A Beginners Levels) GREATGIFT ONLY $199.00 "Offers a Tough Challenge to over 92% of all Chess Players" MOTOROLA KSN1141A KEYBOARD & MONITOR MOVER ARM - YUM-11 ''Solid Steel construction with a finish that ensures stability and safe long life." 1n.8mm x 826mm PIEZO TWEETER NORMALLY $269.00 WiU harde t.p to an amazing 400 Watis continuous Pooer Freq.iercy Response: 1.9kHz to 4Mlz Sensitivity: 1OOdB <at> 2.8 vol1s NOW ONLY $169.00 WAS $39.95 NOW $35.00ea CB BAND SWR METER/ POWER METER/AM MODULATION M_ ETER/ FM DEVIATION METER AND MATCHER ... ALL IN ONE UNIT! CM100 "On Watch" PORTABLE ELECTRONIC MONITORING SYSTEM • For monitoring infants, the elderly, the sick •Transmits all sourds in the room up to 300ft a!Nay. • Battery operated transmitter, receiver oomplete with AC adaptor. * 1 Watt / 10 Watt / 1 0 Watt switchable. WAS$99.95 Model: MS-110 NOW$69.95 Normally $89.95 HARMONY HSW4230PD 2- WAY BASS REFLEX SPEAKER SYSTEM SANGEAN ATS-803A SHORTWAVE RECEIVER * Coverage from 1S0KHz to 30 MHz. * AM/CW/SSB, inbuilt RF Gain control, BFO. * PLL synthesised tunning, LCD display. * Scanning, 9 memories, 12 shortwave bands. * 1OOHz - 20kHz * 30 Watis RMS *82dBWm • Black woodgrain cabinet * 150(\N'/ x 160(0) x 240 (H)mm NORMALLY $299.00/pr NOW $160.00/pr Limited Stocks NOW $39. • Selectable 1 sec or 15 sec Sensing Time • Presettable Hi/Lo alarm . • Stainless steel probe with 1mtr cable. * LED display. ~ ~ "' NOW ONLY $289.00 ' 3yea W~ . NOW ONLY $659.00 inc. tax Spare tip to suit $4.95 * Temperature Range: -40°C to +50°C ~ ' Display:Analog1JigtaJ (4.Sdigit), Bad<-IMsplay. 'Rerges; Vcls, Oms, Curerl (10AAOOC), mA UI\ Free+, Qµ,:itn:e & Dixla Test ' Tout, Im ard relative rrodes. 'MnMax/Average recoo:Jirg rmde wilh f'lt-vMax alert. ' lnpJI alert ard ovenoaJ pro1Edion. ' 0.1% t:asi::0Cero..ra:,,,. • Audible oontinuity. ' lndudes probes ard 1-dster. or · BELL-QUARTZ DIGI-T DIGITAL THERMOM ."'.""'~"' FLUKE 87 TRUE RMS DIGITAL MULTIMETER 240 volt DE-SOLDERING TOOL - 30 Wat • Slim Design • One hand operation • Self-contained suction power and heating equipment • Replaceable tip • Easy Maintenance (tl,v .. . " * ARLEC POWER SURGE PROTECTOR * Surge Gapadty: to 4500 Anµ; • Maximum continual voltage: 275 volts • Reaction time: less than 25 nanoseconds * Clamping voltage: 71 0 volt, 50 amps. • Energy absorption factor: 75 joules ONLY $44.50 MAIL ORDERS: P.O. BOX Q103, SYDNEY 2000 PHONE OREEFIS: (02) 2671385 FAX: (02) 2618905 NOW ONLY $22.95 Ideal for COOl)Ulers, TV and videos etc. ~ Diners Club International s time goes on more and more people are deciding to have a dabble in the fascinating world of laser light. Whether they want to set up a high speed data link, experiment with optics or put on laser light shows, there is a great deal of interest. And who are we to argue with this trend? In fact, this particular laser power A supply and laser tube combination has been used as the basis for a simple light show. More about this later. Bigger power supply The design featured in our November 1990 issue is suitable only for low powered laser tubes, rated at less than 1.5 milliwatts. To get more laser light, you n eed a bigger supply and the bat- Build a bigger laser tery powered approach is no longer really practical. The unit presented here could be run from a car battery but we expect that most people will want to run it from a DC power supply which needs to be able to deliver about two to three amps. Without beating around the bush, let's now have a look at the circuit Design by OTTO PRIMOJ Did you see the laser featured in the November issue but decided against it because you wanted more power. Now here's your chance: a laser power supply which will drive tubes with up to 10 milliwatts rating. 80 SILICON CHIP + 1 2 V O - - - - - - - - - - - - - - - - - - - - - -.....- - - - - a ~ - - - - . 470 + 16VWI 05 06 - - - - - - - - - , - I I - - - H.....+-+N-,1-+__.,,¼---0+V TO LASER TUBE .,. +OV ZD1 5.1V 56n G 10k LASER POWER SUPPLY Fig.1: the circuit is essentially a DC to DC converter with feedback via optocoupler IC2. The 555 timer drives Qt which switches transformer Tl. The transformer output then feeds a Cockcroft-Walton rectifier/multiplier stage. shown in Fig.1. As you can see, there is quite a bit more to it than the circuit featured in our November issue although there are some similarities. First, the circuit is essentially a DC to DC converter, stepping up the nominal 12 volts DC input to the thousands of volts needed to fire and run the laser tube. The circuit has a major refinement though, because it has negative feedback to adjust the high voltage output, depending on whether the tube has fired or not. modes of operation of the 555. In the start mode, it delivers a frequency of around 13kHz with a pulse duty cycle of about 70%, as determined by the setting of trim pot VR1. Normally though, it stays in the start mode for only a few milliseconds after which the laser tube fires. When that happens, current passes through the tube and back through the negative return side of the high voltage rectifier circuitry and transformer secondary. 555 timer Optocoupler control The core of the circuit is ICl, a 555 timer, and Ql which is a BUZ10 Mosfet. ICl is connected as an astable timer and its output pulses from pin 3 drive the gate of the Mosfet transistor, Ql, via a 560 resistor. This Mosfet then pulses the transformer Tl which steps up to high voltage AC on its secondary side. These high voltage pulses are rectified and further stepped up by a Cockcroft-Walton rectifier/multiplier circuit comprising diodes D3-D10 and the associated .0lµF/3kV capacitors. The output voltage from the secondary side of the transformer is controlled by varying the frequency and pulse width of the signal to the gate of the Mosfet. In effect, there are two In doing so, the laser tube current must pass through the light emitting FACING PAGE: the laser tube and its power supply. The holes drilled in the plastic tube let you see when the tube is operating. diode of ICZ and the associated 1000 resistor (see the lefthand side of the circuit of Fig.1). ICZ is an optocoupler and when current passes through its LED section (pins 2 & 1), its Triac section, between pins 6 & 4, conducts. This brings trimpot VRZ into play and so the frequency of the pulses from ICl rises markedly, to around Z0kHz or so. Also, the duty cycle is now close to 50% (set by diodes D1 & DZ) so that the efficiency of the inverter is close to optimum. Hence, the inverter (consisting of ICl and Ql) provides a lot of herbs to the laser to start it and then is throttled back to sustain the laser discharge at a set current level, in this case, around 5 milliamps. Current drain of the DC-DC con- The laser tube in its naked form: even though it is quite big, its rating is modest at 4 to 5 milliwatts. The anode is at the right hand end. JANUARY 1991 81 verter, with the laser tube running , is around 1.6 to 1.8 amps. This can be supplied by a 12V battery or DC power supply. Construction A number of prototypes were built for this article, two of which are shown here. The first is the simpler .01.t7ffliFH!.I .o3,\ Jiic:::o,i~ I- PARTS LIST 1 SmW laser tube 1 plastic utility case , 130 x 68 x 41 mm (Altronics H-0203) 1 PC board, 105 x 59mm , (cut to suit plastic case) 1.ferrite transformer core, Philips FX3720 or Siemens B66 337G-X 127 1 plastic former to suit transformer, Philips DT 2723 or Siemens B66 272-C-1001T1, with prewound secondary (see text) 1 TO-220 mini heatsink (for 01) 1 405mm length of plastic tube, 50mm O.D. 1 40mm-length of 15 x 10mm Handitube 2 metres of EHT cable (see text) 1 plastic cable clamp 1 nylon screw and nut (to suit cable clamp) 1 1.5-metre length of 0.8mm enamelled copper wire Semiconductors 1 5_55 timer (IC1) 1 MOC3021 optocoupled Triac (IC2) 1 BUZ10 or BUZ71 Mosfet (01) 2 1N914 silicon diodes (D1, D2) 8 1N4007 silicon diodes (D3 to • D10) 1 5.1 volt zener diode (2D1) Fig.2: the wiring diagram of the laser power supply. Note that an additional ballast resistor (2 x 22kQ 2W in parallel) is mounted at the anode of the laser tube, in series with the 68kQ resistor from the power supply board (the scheme is similar to that used for the laser described in the November 1990 issue). of the two and is the one which we'll highlight. It is built in two parts: a plastic tube containing the laser and a separate plastic case to contain the DC-DC converter. Inside.the plastic case is a PC board w hich accommodates the inverter transformer and the rest of the components . Before assembling any components onto the board, we suggest you check it for any faults in the copper pattern or undrilled holes. These should be fixed before going any further This done, check that it will fit securely into the base of the specified plastic u tility box. This is important because it is desirable that no screws be used to mount the board into the box, especially at the high voltage end of the PC board. That point confirmed, we suggest that you then wind the transformer. Winding the secondary winding, which goes on first, is not an easy job. There are 700 turns of 0.2mm enamelled copper wire required. These must be carefully layer wou nd, with Mylar insulation between each layer. Fortunately, kits for this project will be supplied with the transformer secondary already prewound. All that you will have to do is to add the primary winding, which is 15 turns of 0.8mm enamelled copper wire. The start and finish of the prinary winding should come out of the former on the opposite side to the secondary winding terminations. Make sure that the primary and Capacitors 1 470µF 16VW electrolytic 1 .039µF metallised polyester 1 .01 µF metallised polyester 4 .01 µF 3kV ceramic Resistors (0.25W, 5%) 1 68kQ SW wirewou nd 2 22kQ 2W (on laser tube) 110kQ 1150!2 1 100!2 256!2 1 2kn cermet trim pot (VR 1) 1 2kQ multiturn trimpot (VR2) 82 SILICON CHIP Inside the laser power supply case, showing the general arrangement of the components. Be careful not to work on this equipment when it is powered up, as the circuit generates very high voltages to fire the laser tube. Inside the deluxe version of the laser showing the arrangement of the mains power supply and the motor driven mirrors to deflect the beam. The laser was compliantly mounted inside metal clamps using silicone sealant. Note the finned heatsink for the Mosfet switching transistor. secondary winding start and finish leads are thoroughly scraped clean and tinned with solder. The transformer is then installed on the PC board. The lower core half is placed onto the board, then the wound former placed into it and the top core half placed over that. Finally, a long screw is passed through the whole assembly and fixed with a nut and nylon washer to secure it. Do not over-tighten the nut, otherwise you run the risk of the core cracking or being distorted which will increase the current drain. Solder in the four transformer leads and then proceed with assembly of the remaining components, except for the Mosfet, Ql. This is mounted on the outside of the plastic box, together with its own TO-220 heatsink. Note that the eight high voltage rectifier diodes are mounted in pairs, This is an end-on view of the case for the simpler version, showing how Mosfet Qt is mounted. The heatsink is necessary to ensure adequate cooling. with their flying ends covered with a short length of plastic sleeving. You will need to drill four holes in the plastic box, two in each end. At the low voltage end of the case, you will need a single 3mm hole to mount the transistor and its heatsink and a 10mm hole for the transistor leads. At the other end of the case, you will need a 3mm hole to mount the cable clamp and a 6mm hole for the high voltage output cable. Mounting the laser As mentioned above, this version of the laser uses a simple presentation 'with the tube itself housed in a length of 50mm OD plastic tubing. This is fitted with Perspex end pieces, with a hole drilled in the output end, to offer :p.o obstruction to the laser light. The laser tube is compliantly mounted in the plastic tube by means of short lengths of 15mm (ID) by 10mm (wall thickness) Handitube, a foam rubber commonly used for lagging hot water pipes, padding for roof racks and so on. A short length is placed over each end of the laser tube before it is put into the plastic tube. A nice touch with the plastic tube is to drill a number of holes along its length. This is not necessary for ventilation but lets you see the tube "lazing" away. It is also a good idea to spray the tube and its endpieces matte black, for the sake of appearance. The EHT cable from the power supply to the laser tube was merely coax cable in the prototype but two lengths ofEHT cable will be supplied with kits. An additional ballast resistor, in the form of two paralleled ZZkQ 2 watt resistors, needs to be attached to the laser anode, before the cable is connected. Setting up When all the circuitry is assembled and connected (and checked for errors!), you are ready to set the laser power supply. Set trimpot VRZ for maximum resistance by rotating the screw adjustment clockwise until it clicks. Set VR1 fully anticlockwise, then adjust VR1 until the tube just fires. Measure the DC voltage across the 100Q resistor and adjust VRZ until the voltage is 550 millivolts. This corresponds to a tube current of 5.5 milliamps. By the way, there is a choice of two tubes for this project. One is rated at Where to get the kit A full kit of parts for the laser described here (mounted in a plastic tube) is available from Oatley Electronics who also own the design copyright on the printed circuit board. The laser power supply kit, complete with plastic utility box, PC board, and transformer with prewound secondary, is available for $59.90. Oatley Electronics have two tubes to suit the power supply: a 2-3mW tube at $177 and a 4-5mW tube (same physical size) at $259.00. Alternatively, Oatley Electronics can do a package deal comprising the laser power supply kit as described plus the 2-3mW laser tube, plastic tube and all hardware, for $240. Certified postage on any of the above items is $5.00. For further information, contact Oatley Electronics at PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. JANUARY 1991 83 'MUSIC-ON-HOLD' KIT Comercially this unit could cost 1000's of dollars. Simply press the 'Hold' button and your caller is able to listen to your selection of radio music or tape. Press the release button to resume the conversation. When the line is captured there is an audible pulser and a flashing LED, to remind you. Connects across your existing phone line. ~ As featured in fllMl!!!!f September '90 SPECIAL JANUARY PRICE $39.95 ,~ . Price does not include radio. sec approved 12V DC plugpack $14.90. LASER PRODUCT ACCESSORIES X·Y SCANNER with Dielectric Mirrors for 633nm (He-Ne). These units work great for Beam Positioning Impedance: 8 ohms & Low Speed Scanning. Input Power: 2 Watts Angle of Deflection: ± 12° Frequency Response: DC • 120 Hz ~--~·,, ONL V $220.00 POLYGON SCANNER comes complete with motor and driver. Has LED indicator which lights when the motor speed is locked at 4667 RPM. The deflection is 90° and the mirror is 8 sided coated aluminium. Input Voltage: 18 · 24 VDC (Fuull Speed) ~ Input Current: 200mA Sweep Frequency: 622.3 Hz Q . Q ONL V $129.50 COLLIMATOR which can be used to reduce the laser beam width $79.00 TV TRIPLER The deluxe version of the laser project was built into an aluminium case fitted with a small fan for cooling. The keyswitch was fitted to stop unauthorised use. 2-3mW while the other is rated at 4-5m W. Both tubes are identical in appearance and required current. The difference in rating comes about from the quality of the mirrors and the precision of their adjustment, which affects the total light output. Deluxe version Used in a well known late model TV, should also be a suitable replacement for many other units. WE HAVE A SMALL QUANTITY AT A SPECIAL PRICE OF ONL V $12.90 ea SEE IN THE DARK! with our INFRA RED NIGHT VIEWER . We have good stock of the 6032A tubes. This is your opportunity to build a prod· uct which commercially cost 1000's of dollars at a fraction of the cost. We supply the electronic kit, a 6032A Image Intensifier tube, and the case components for only. As mentioned earlier, two versions of this laser have been built. We'll make a few comments on the more deluxe version now. It was housed in a substantial case made from sheet aluminium. The case houses a mains power supply which provides 12 volts DC to the laser power supply board. The photos show the details. Also included in the case are a pair of motors at the business end of the laser tube. These drive compliantly mounted alumininised mirrors which deflect the beam. By feeding the motors with different levels of DC they run at different speeds and thereby generate all sorts of interesting Lissajous patterns - great for a simple laser light show. SC ONLY $339.00 BRAND NEW TUBES The 6032A tubes are BRAND NEW and perform well with a good infra red torch. Torch and Lenses are not supplied NICAD BATTERY PACKS HIGH QUALITY JAPANESE 500mAH penlight batteries for under $2.00 ea. These are 7.2V multipurpose "Six Packs" that you can easily reduce in size, or dismantle to individual cells. BULK ENQUIRIES WELCOME. $10.90 per Pack These will not last at this price so get your order in quickly 1.5V to 9V Convertor in 'Silicon Chip' November 1990, uses only 3 components and has multipurose a lications, $7.99, a bar ain at this rice. OATLEY ELECTRONICS fiiiii!!!iil l--1 84 rili:5J PO BOX 89, OATLEY, NSW 2223 Telephone: (02) 579 4985 ~ Fax No: (02) 570 7910 Certified p&p $4-$6 Aust. NZ add $2 SILICON CHIP A closer view of the motors and their compliantly mounted aluminised mirrors which are used to deflect the beam. By operating the motors at different speeds, you can use the laser to generate all sorts of interesting patterns. Save $491.00 on an upgrade of your XT to an AT Are you tired of waiting for your present computer to get things done? But you don't want to throw out a good reliable machine! This solution could be the answer. We will supply a conversion kit which includes a state-of-the-art 20MHz motherboard, fast memory and a 16-bit controller card for your present hard disk. This kit will bring up the performance of your machine to those costing $4,000 to $5,000. This will improve the speed of your new machine by as much as 20 times that of your present machine. THE UPGRADE INCLUDES: A 'Rocket-Fast' 20MHz 'AT' motherboard, complete with 1MB of high speed RAM. This can be expanded to 2MB (at additional cost). Full LIM EMS 4.0 additional memory support built-in (which means no need for expanded memory cards. Normally this unit sells for $745.00 As well: A fast 1:1 interleave 16-bit disk controller. This means a data transfer speed 6 times faster than with an XT controller on the 8-bit bus. Normally this unit sells for $245.00 Your price for both of these units is only: $499.00 SAVE $491.00 •rzi Due to Technical advances, products we supply may in some cases vary from those pictured. In all cases the products supplied are guaranteed to perform to an equal or higher standard than those pictured SEE OUR OTHER ADVERTISMENT IN THIS ISSUE FOR THE FREE CATALOGUE OFFER Electronic Solutions 5 Waltham St Artarmon 2064 PO Box 426 Gladesville 2111 Telephone: (02) 906 6666 Fax: (02) 906 5222 JANUARY 1991 85 . CIRCUIT NOTEBOOK 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. 1.2k Constant volume amplifier The basic idea of using a Fet to control the gain of an op amp was gleaned from "110 Operational Amplifier Projects For The Horne Constructor", by R.M. Marston (pp 2932), but this circuit differs significantly in two respects. One involves the derivation of the control voltage, and the other is the use of a single sided power supply, in place of the original dual supply. The op amp functions as an inverting amplifier whose gain is controlled by a dividing network in the feedback loop, formed by Fet Ql (MPF102) and a 330kQ resistor. With zero bias on its gate, the Fet's source to drain resistance is low. As the gate is made negative, relative to the source, the Fet's resistance increases, becoming virtually an open circuit at large negative voltages. The output from the op amp is fed to emitter follower stage Q2 (BC548) and the buffered output signal then rectified by D1 & D2 to produce a negative control voltage. This control voltage is fed to Ql's gate. Thus, if the signal input to the op amp increases, an increasingly negative voltage is fed to the Fet's gate. This increases Ql 's resistance which in turn increases the feedback applied to the op amp input and thus Diode test adaptor for multimeters If your ageing analog multimeter doesn't have a diode test facility, this simple circuit can be whipped up to do the job. What it lacks in sophistication is made up in cost effectiveness - after all, a new meter will set you back $50. The circuit consists of nothing more than a swich in series with an 820Q resistor and 3V battery. It 86 SILICON CHIP 47k G 0.1 INPUT <>--fl-➔YMr-+---9 47k Fig.t: the constant volume amplifier is based on op amp ICt whose gain is controlled by Fet Qt in the feedback loop. Q2 buffers the op amp output & this signal is then rectified by Dt & D2 to produce a control voltage for the Fet (Qt). reduces the op amp gain. The time constant is determined by the value of the capacitor following the diode network. The value shown (lµF) is a good compromise between speed and recovery time. The circuit handles input variations of about 30dB for an output variation of just 3dB. Once the maximum signal input is exceeded, signal distortion occurs but without further increase in output. The input resistor "R" is selected to handle the likely maximum input; a value of 200kQ per 1V RMS is a rough guide. o----r----o s1\ TO PROBES -1 TO MULTIMETER 3V..Z.. o----I---o simply connects across the meter input and is used to measure the foward voltage drop of the diode The prototype was used to provide automatic gain control in the audio stage of direct-conversion 40-metre receivers, including one based on the suggestion by Garry Cratt, VK2YBX, in the October 1990 issue of SILICON CHIP. It gave very gratifying results, by levelling the output and preventing "blasting" on very strong signals. The circuit could also be quite useful as part of a microphone amplifier chain, such as one feeding a modulator. C. Wallis, VK2DQE, Miranda, NSW. ($30) under test. When the diode is forward biased, you should get a reading of about 0.65V. With nothing connected or if the diode is reverse biased, the meter reads the battery voltage. S1 is included for convenience and allows the circuit to be switched out so that the multimeter functions normally without unplugging any leads. David Eather, Brisbane, Qld. ($10) .12v-----------4.,_.---------..----------, 16 IC5a 4069 2.7k IC5b 14 IC1 4040 1 OUTPUT ... 2.7k 11 1 8 .,. +12V 10 16 M2851 ·:l +12V 12V IC2 11 4040 • ..,. ..,. 01 1N914 10k .,. ... Precision timer goes to 46.6 hours This timer runs from the mains and uses two cascaded 4040 12-stage ripple carry counters. The desired time interval is obtained by summing selected counter outputs in two 4input NOR gates. In more detail, the circuit works as follows. A 50Hz signal is obtained from the transformer secondary winding and is squared by IC5a and IC5b, two sections of a hex inverter. The 50Hz squared signal is fed to the clock input, pin 10, of ICl. Each of the 12 outputs goes high for twice as long as the succeeding output. Accordingly, each output goes high as shown in Table 1. With eight of these outputs summed by NOR gates IC3a and IC3b, almost Table 1 IC1 pin pin pin pin pin pin pin pin pin pin pin pin IC2 9 7 6 5 3 2 4 13 12 14 15 1 20ms 40ms 80ms 160ms 320ms 640ms 1.28s 2.56s·' 5.12s 10.24s 20.48s 40.96s pin 9 pin 7 pin 6 pin 5 pin 3 pin 2 pin 4 pin 13 pin 12 pin 14 pin 15 pin 1 81 .92s 163s 328s 655s 21.84 mins 43.69 mins 87.38 mins 175 mins 349 mins 11.65 hrs 23.3 hrs 46.6 hrs any time interval can be precisely obtained. Bill Jolly, Nambucca Heads, NSW ($30) Wanted: Your Circuit Ideas Have you got a good circuit idea languishing in the ol' brain cells. If so, why not transfer it to paper, send it into us. You'll not only make a few dollars but you'll also help save us from "circuit burnout" syndrome which happens to anyone who has to generate too many circuit ideas in too short a time. We'll pay up to $50 for a really good circuit. So sketch your circuit out, write a brief description of how it works and send it to: SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. Or fax (02) 979 6503. Claytons alarms with no IC drivers If you want a .12v simple LED flasher there is no need to resort to a 555 timer or LM3909 IC. You LED1 can do it with a (10mm) flashing LED which has its own inbuilt LED2 RED driver. The first cir- FLASHING cuit is the simplest and flashes two =II LEDs in unison. LED 2 is a flashing LED while LED 1 can be a 10mm jumbo LED. This is an eye-catching and effective flasher. Circuit 2 flashes two LEDs alternately. +12V When the flashing LED 2 is off, conventional LED 1 is LE02 RED . on and vice FLASHING versa. LED1 K. Young, Nunawading, Vic. CHASSIS ($20) JANUARY 1991 87 COMPUTER BITS BY JENNIFER BONNITCHA Hard disc failure: what to do when disaster strikes "Hello, is that Support? I'm having a problem with my computer. Something about a no-longer existent directory in WordPerfect not able to be read. I also get a message telling me there is a general failure reading drive C. What's the problem?" All hard discs fail eventually. Most can be expected to last for many years, however some will fail after only a few month's use for various reasons such as power spikes, faulty controller card, poor maintenance, the current bogey man - the virus, and just plain bad luck. Nothing can destroy one's faith in technology faster than the news that the last year or more of work has been lost. Be sure that your data is secure by making backups and keeping them in a safe place. The more diligent among you will more than likely have a backup procedure already in place. If you don't, consider implementing one immediately. Although any system can be "fixed" , the technician's idea of fixed and your idea of fixed will usually be totally opposite. You can replace any part of the computer and thus "fix" a problem - unfortunately you can't always keep any data stored on the computer. Recovering lost or damaged data is almost an art as it can be very time-consuming, difficult and in some situations, nigh on impossible. You can put it off until tomorrow, next week or next month but if you do, eventually you will lose valuable data and realise the folly of your ways. 88 SILICON CHIP Take the case of a very busy public relations company. Even though they backed up their data regularly to disc, this did not include their spreadsheet data since they "hadn't gotten around to it". Hard disc problems surfaced and there was no backup to save them endless hours of work (and dollars). BACKUP!! BACKUP!! BACKUP!! BACKUP!! So let's look at the current backup options and ways of decreasing the anguish caused by a hard disc crash. When to backup All users should have a plan for regular backups of data. Perform the backups at an interval suitable to the amount of activity on the system. Some users will find that daily backups are required (especially with ac- counting systems, etc) while others will find that a weekly arrangement is more suitable. Using your backup system to its full advantage, make a complete backup of your computer once a year, including all program and data files . This way, you will be able to quickly rebuild your hard disc structure. If you add or delete applications from your computer, perform the entire system backup again. Make a point of taking monthly backups of all data directories. Lastly, make a backup of your most popular applications on a weekly basis. This may seem like a lot of time and effort, particularly if you use floppy discs to backup. However, it is nothing compared to losing months of accumulated work. How then to stay out of trouble? How to backup Backups ,should always be performed to a removable medium. Don't be lulled into a false sense of security if your word processing system has backup options for timed backups (like WordPerfect) or creates "backup" files i(like WordStar and MS Word). Thes~ are in fact either temporary backtips of the current file which are deleted when the program is exited norm~lly (WordPerfect), or. an older version of the current file (WordStar, MS Word). When performed to a removable medium, you have fewer worries if the computer is stolen, a fire breaks out, the office sprinklers are accidentally activated, or the desk holding your computer collapses, etc. Backups should be performed on That's fine, so long as you don't have a faulty DMA chip. Many of the diagnostic utilities will check the DMA chip and thus report whether your computer can reliably support these fast backups. The humble DOS backup and a large pile of diskettes is the only way for a large number of computer users. If you take the time to explore the command, you will find that, apart from increased operator interaction and the number of diskettes, it can perform just as well as the tape backup. Using DOS backup For most users, backing up the hard disc involves copying the hard disc files onto one or more floppy discs using the DOS Backup command. By using the parameters shown here, the entire hard disc contents will be backed up. the chosen media on a rotating basis. If using a weekly tape backup system, a set of three tapes should suffice. A daily backup system would require five tapes. When restoring data, problems can occasionally arise with the tape backup itself. If you use the same tape each time, you can go no further - if you use several tapes you can at least recover some data rather than nothing at all. Try to think of every possible problem and plan your backup system accordingly. Thero is little point having a wonderful backup system in place if the tapes/ diskettes are stored right next to the computer. Fire, flood and thieves are not selective. Tape backup This is a reliable and effective method of preserving data. You should never have to lose more than one day's work under normal circumstances. Investigate thoroughly the tape backup system you fancy - it should be easy to use and as bulletproof as possible. Use the system regularly and try restoring data on a semiregular basis to satisfy yourself that it is working reliably. Bernoulli box Provided you use the Bernoulli box cartridge in this instance for archiving purposes alone, you should have no problems. Although it provides a convenient removable storage medium and has performance similar to a hard disc, the cartridges do wear out when continually used as a hard disc substitute. Thus, the reliability of the device as both a "hard disc" and backup medium should be viewed with caution. Floppy discs The time-honoured method of backing up hard disc data is the humble diskette. With backup programs like DS Backup, Fastback etc, you can squeeze your data so it takes much less space than the traditional DOS backup. However, the quality of the backup depends on several factors. First, this style of program typically uses Direct Memory Access (DMA) to transfer the data. DMA is the process of using chips inside the computer to send data to and from memory without using the CPU. The backup program can be sending data to the diskette while it talks about readying another diskette, so the computer is literally doing two things at the same time. Data is always on the move and so the backup process just flows along. The Backup command copies one or more hard disc files to diskette in a special format that allows a single file to occupy more than one diskette. Files copied with this command may only be used again once they have been processed using the DOS Restore command. The general syntax of the Backup command is as follows: BACKUP [d:][path][filename][.ext) [d:) [IS] [JM) [/D:date) [/T:time) [/L] [d:] [filename) Backup, like many DOS commands, refers to both the source and destination file(s). The parameters or switches, which may be entered in any order, have the following meaning: d: this is the disc drive. Drive specifications differ between DOS 2.x and 3.x: DOS 2.x - unless the computer has a second hard disc, the first drive specification is C. If the system has only one diskette drive, the second drive is A. Note that the second drive specification must be used in this command. DOS 3.x - source and target drives may be of any type; ie, diskette to diskette, diskette to hard disc, hard disc to diskette etc. Path designates a specific directory in the directory hierarchy where the file or files may be found . If no directory is specified, the current directory is assumed. Filename can be used to specify single files or global file characters. If the filename and extension parameters are omitted, the entire directory is copied. Ext specifies the filename extension and may be a global character. /S is a switch. Osing this switch, JANUARY 1991 89 You may think that your hard disc will never crash but rest assured that, sooner or later, it definitely will. Backing up can save you time & dollars. filename, Backup places a file called Backup.Log in the root directory of the disc containing the files being backed up. The log file contains a record for each file processed and identifies the diskette number of the backup-up file. If the backup log file already exists, Backup appends the current entry to the file. You can use the backup log file when you need to restore a particular file from a floppy disc, but you must specify which disc to restore so that the Restore command does not have to search for files. Backup now writes only two files on each backup diskette (Control.nnn and Backup.nnn, where nnn is the diskette backup sequence number) and for this reason, you cannot use an old version of the Restore command for files backed up with the DOS 3.3 command. DOS 3.3 Restore can, however, restore backup files generated by previous versions of the Backup command. Restore also no longer restores the COMMAND.COM or system files IBM.COM, IQ.COM, IBMDOS.COM and MSDOS.COM, thus enabling Restore to load files onto a hard disc without the often undesirable result of replacing the operating system files. The global characters referred to above are the wildcard characters * and ?. The ? character may replace any individual character; eg, SU?? would act on files called SUSI, SUZY, SUZE, etc; whereas SU* would act on files called SUSI, SUZY, SUZE, SUSAN, SUZANNE etc. Using the Restore command Backup also copies all subdirectories below the directory level specified in the path parameter. It's particularly useful if you have several sub-subdirectories. Thus, to backup the entire hard disc specify Backup C: \ A:/S /M is another switch. Following a full backup, this switch is useful since only those files that have been modified since the last backup are copied. Sometimes this is called an incremental backup. /A: DOS normally erases all the existing files on a backup diskette before commencing the new backup. Using the /A switch, you can add files to the diskette's existing files. This is often used in conjunction with the /M switch. 90 SILICON CHIP ID: the date switch enables you to backup only those files you modified on or after a certain date. For example, to backup only those files created since May 15, 1990, the parameter is /D:5-15-90. This switch is often used in conjunction with the /M switch. /f: similar to the date switch, it backs up only those files that you last modified at or after the specified time. /F: new to DOS 3.3, this switch causes the target diskette to be formatted if it is not already. For the switch to function, the Format command must be accessible by the current path since it is an external command. /L makes a backup log entry in the specified file. If you do not specify a This command restores files from a backup diskette to their original condition. Restore is used to place one or more files copied by the Backup command back onto the hard disc. If a file is accidentally destroyed, it may be recreated with this command if it has been copied onto a diskette using Backup. If a hard disc fails, this command restores the Backup copies after repair. Backup and Restore are also useful for transferring an entire subdirectory to another hard disc. The syntax of the Restore command for DOS 3.3 is as follows: RESTORE [d:](path] [filename] [.ext] [d:] [IS] [IP] [/B:date] [/ A:date] [/E:time] [/L:time](/Ml[/N] d: this specifies the first source drive and then the target drive. Note that the source drive must be included in the command. path: this is the directory to which the file or files are to be restored. If no path is specified, the current directory is assumed. filename: single files or global file characters may be specified. If the filename and e~tension parameters are omitted, all files in the directory are restored. ext specifies the filename extension and may be a global character. /S all subdirectories below the directory level specified in the path parameter are restored. IP when you include this parameter, DOS displays a prompt before restoring files that have been changed since the last backup, or files which have the Read Only attribute on. Use this switch when you want to perform a partial restoration from a complete backup of a directory or all hard disc files. For example: RESTORE A: C: \/SIP restores all files from Drive A to the hard disc Drive C, starting at the Root Directory, including subdirectories as appropriate and prompting for each file. /B:date restores only those files last modified on or before the specified date. /A:date restores only those files last modified on or after the specified date. /E:time restores only those files last modified on or at an earlier time than specified. /L:time restores only those files last modified on or at a later time than specified. /M restores only those files modified since the last backup. IN restores only those files that no longer exist on the target disc. Notes on Restore Restore was modified in DOS 3.3 so that it no longer restores COMMAND.COM and tpe system files IBMIO.SYS, IO.SYS, IBMDOS.SYS and MSDOS.SYS. This allows Restore to be used to load files onto a hard disc without overwriting these vital files. An interesting feature of the Restore command is its ability to recreate deleted subdirectories if you specify the IS switch. This is sometimes desirable when you restore an application and require certain data TRIM files, for example. Fortunately, this doesn't have any serious side-effects since the directory can be deleted if its restoration was unintentional. As with Backup, Restore returns exit codes upon completion which could be tested in a batch file using the Error level condition of the IF command: 0 Normal completion 1 No files were found to restore 3 Terminated by user 4 Terminated due to error If you need to restore data to a hard disc, generally start with the oldest discs first, particularly if partial backups have been made since the last full backup. This process adds to the hard disc all those backup files that have been created or modified since the last full backup. If the hard disc contains new files that are not on the backup diskettes, they are not erased since unlike Backup, Restore doesn't erase files on the disc before copying the backup files from the diskettes. The importance ofregular backups cannot be stressed strongly enough. You may think serious data loss will never happen to you - rest assured it definitely will! SC E-1 LAMINATED POWER TRANSFORMERS PCB MOUNT STOCK RANGE PCB mount ex-stock in sizes from 2.5VA to 25VA with secondary voltages from 2 x. 6V to 2 x 20V. Triple output models also available for logic circuits. Chassis mount manufactured to order in sizes from 2.5VA to 1KVA in E-1 and C core. CHASSIS MOUNT TO ORDER 1NN EA Wl N 0 !NG We are the largest ex-stock supplier of toroidal power transformers in Australia. Our standard range consists of the U.K. manufactured ANTR_IM range in 10 VA sizes from 15VA to 625VA. All have a single 240V primary and dual secondary windings ranging from 2 x 6V to 2 x 55V. Our local manufacturing facilities supplement this range by manufacturing specials to order. Models are available from stock to suit most project kits. Comprehensive data sheets are available on request. Enquiries from resellers and manufacturers are welcomed. Prices are extremely competitive and generous trade discounts apply for quantity. HARBUCH ELECTRONI JANUARY 1991 91 LCD readout for the digital capacitance meter Did you decide not to build the 4-digit capacitance meter published in May 1990 because it was mains powered? Did you want a liquid crystal display too? If so, have a look at this re-design of the circuit which uses a 4½-digit LCD panel. By BARRY NAUJOK The heart of this new design is the 74C946 (IC3). It is a 4½-digit LCD counter and decoder/driver which is used to drive the LCD panel. It replaces the 74C926 (IC3) used in the original design. Because the new circuit uses a liquid crystal display instead of the 4-digit LED display, its power requirement is greatly reduced and it can be supplied by batteries (or an external DC plugpack). Since the design uses batteries, a "low battery" indicator has been added to the circuit. Let's see how the new circuit works. The nulling circuit, using IC1, is still the same as the LED version and the reference oscillator is also the same. Gating oscillator The gating oscillator (IC2, IC8d and IC7b), wired for monostable operation as before, measures capacitors up to 19,999µF compared to 9999µF for the LED version. To charge a capacitor which is twice the value in the same time as for the previous version, the timing resistors have been halved to keep reading updates at a reasonable rate (45 seconds for a 20,000µF capacitor is quite a long time). But when this gates the reference oscillator (IC4), a capacitor of say 6800µF would read 3400µF. To overcome this, the clock frequency from Slc is fed via exclusive-OR (XOR) gate IC10c and the associated RC network. IC10c operates as an edge detector and effectively doubles the 92 SILICON CHIP clock frequency which feeds pin 32 of the 74C946. Latch and reset The 74C946 control inputs for latching and resetting are different to the 74C926. To reset IC3, the reset pin (33) must be brought low (normally it is held high). Pin 10 ofIC6 has a signal opposite to that required by IC3, so the signal is inverted by IC9d. To latch the display, the store pin (34) must be brought high. To achieve this, pin 4 ofIC6 has to be inverted by IC9e. Over-range indication is also entirely different to the LED version. The over-range is driven by the Carry Out (CO) and the half-digit outputs of IC3. During each cycle, the CO output goes high when (and if) a count of 9999 is reached. This goes low again on the next clock pulse. It always goes high every 10,000 counts. Because the meter has a "full scale" of 19,999, the over-range needs to trigger on the second CO pulse so the CO signal is fed into a NAND gate, consisting of D5, D6, Q3 and two 10kn resistors. The other signal to this NAND gate, fed via D6, is the half-digit signal which is demodulated from the backplane. The output of the NAND gate is connected to the clock input of a Dtype flipflop, IC7a, and the output is latched high until it is reset by IC6. If the output goes high, it is modulated with the backplane signal (BP; pin 5 ofIC3) by IC10b which drives the"+" segments on the LCD. Battery power The circuit of the LCD version needs about 9V DC. Ideally, this could be supplied by 6 AA cells in a suitable holder, inside the case. This 9V DC supply is fed to two 78L05 5V regulators (REG1 & REG2) to drive the circuitry. If the battery voltage drops below 6.6V (1.1V per battery), the regulator outputs start dropping below 5V and also become unstable. This condition means that some sort of low-battery indicator is needed, because low batteries can lead to inaccurate capacitance readings. Therefore, battery indication is provided by IC12, ZD1 and their associated resistors. The first stage in the battery indicator (IC12a) is a voltage comparator. A 3.3V reference is generated by ZD1 and is fed into the non-inverting input of IC12a. The unregulated power supply (nominally 9V) is divided by two by the two 100kQ resistors and fed into the inverting input of IC1a. Normally, the output of IC12a is low as the input at pin 2 is higher than the 3.3V reference. When the battery supply drops below 6.6V, the output goes high. The second stage of IC12 is configured as an XOR gate. One of the inputs (pin 6) is the backplane signal while the other is the output of IC12a. The output of this is used to drive the "arrow" symbol on the LCD. This then, is the "low battery" indication. Brief LCD operation For anyone who is confused by the operation of the LCD, it requires an continued on page 96 Fig.1 (right): the LCD version of the capacitance meter is similar to the LED version, but uses an LCD panel instead of the original 7-segment LED readouts & a 74C946 LCD decoder/ driver instead of a 74C926 LED driver. - nFO pF JlE,.,. :- 1oopF .i. STY RO I CALE_J VR2 6 5k 1k $ "'"J 33 ,_: 1MS I 5 ':' 1 ~ J.. ~ lN 4002 07 1.,. L 95 0kHz J: 10 16VWI RBLL .,. . - ... 8 ; 7.2-9V I IC4 7555 I 0.1.., I I ic1 1 V, F I L-. 1¾ .,. 1 .,. · -:- HfflI1 ":"' -:- 22 + 25VWI R2 15 IC5 4518 uF nF . uF i 9.5kHz .,. 0.1I .L, CK vcc 14 I 16 8 .,. IC6 4017 I I --♦♦ H ~ · .,,.- - I _ t='--<--+5V 1 OOk .,. 47 + 16VWI Z01 ~ 400mW .,... J I 1 ~ 8 I ? 2 4 15 R 4 10 100k 10k __.11 ~•• •l .,,._+-_ ~ .,. 0.1I. · - >'--W,,,_➔--=I 11 9 12 05 1 31 EN 34 ST 33 R 32 CK vcr.---.... 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L~~~tt . . r··~:~) 'i 1, ,,-, ,,... r • _ .1 B~ ? 100k I I [11 100k i b ~VER-RANGE ~ + 5v I OP41 c52d DP3 IC10d I ~~ tt 35 29 w 9 e3 . /4 1 13 :: : 13 g311-'-"----R3 a 20 35 a4 b4 21 34 b4 4 22 7 t4 cd 4 23 6 d4 24 5 4 ~: 26 36 e 25 37 g4>-'-----,g4 e3 5 BAzirinv 38 1 4 8 12 16 33 28 BP BP DP1 DP2 DP3 OP4 l 1 l2 27 3 1/2DE-+----,--t1/20 a1 37 21 a1 b1 38 20 b1 19 39 c1 c1 d1 40 18 d1 ~ 39 17 el 12 ~ 4 22 l1 1 3 23 91 91 25 32 32 6 24 b2 7 b2 15 02 02 8 9 14 • 2 d 10 13 • 1C3 e2i,:.=.----=te2 24151 LCD 12 26 74C946 12 12 (DSE) g2 11 27 92 a ;; ~o . 3 b3 b3 15 11 03 03 d ~~ 10 d3 28 CO I ? 06 2x 1N914 ~ ~ 10k* Silicon Chip BACK COPIES or Car Alarms; ss Loop Tape · ox; New Life yers; Old-Time Crystal Doorbell; High Performance AC Millivoltmeter, Pt.1; Discolight Light Show, Pt.2; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. May 1988: Optical Tachometer For Aeromodellers ; High Energy Ignition For Cars; Ultrasonic Car Burglar Alarm ; Walkaround Throttle For Model Railroads, Pt.2; Designing & Building RF Attenuators; Motorola MC3334P High Energy Ignition IC Data. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vader Voice ; Motorola MC34018 Speakerphone IC Data; National Semiconductor LM12 150W Op Amp Data & Applications; What Is Negative Feedback, Pt.4. June 1988: Stereo Control Preamplifier (Uses LM833), Pt.1; Brea ition For Cars Using Hall · a-Fast Nicad Battery Cha ht Controller (Uses PIA D Probe & Preamplifier; What Is Negative Feedback, Pt.2. October 1988: Stereo FM Transmitter (Uses Rohm BA1404) ; High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band; Queensland's Powerful Electric Locomotives. July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid; Booster For TV & FM Signals; The Discolight Light Show, Pt.1 ; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback, Pt.3. 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, What You Need To Know; Diesel Electric Locomotives. March 19 · Telephone Player; Bui! For Radio-Ca Radio. August 1988: Building A Plasma Display; Universal Power Supply Board ; Remote Chime/ December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor For Shortwave Receivers ; Electronics & Holden's New V6 Engine; Why Diesel Electrics Killed Off Steam; Index to Volume 1. January 1989: Line Filter For Computers ; Ultrasonic Proximity Detector For Cars ; Simple Computer Sound Repeater; 120W PA Ampl ifier (With Balanced Inputs) Pt. 1; How To Service Car Cassette Players ; Massive Diesel Electrics In The USA; Marantz LD50 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 ; 32Band Graphic Equaliser, Pt.1 ; Stereo Compressor For CD Players ; Map Reader For Trip l ,---------------------------- - -- -- Use this handy form to order your back copies Please send me a back issue for: O August 1988 o September 1988 O January 1989 o February 1989 O June 1989 0 July 1989 O November 1989 O December 1989 O April 1990 o May 1990 0 September 1990 O October 1990 0 March 1988 O October 1988 0 March 1989 0 August 1989 O January 1990 O June 1990 0 November 1990 0 May 1988 0 November 1988 0 April 1989 0 September 1989 0 February 1990 0 July 1990 O December 1990 Enclosed is my cheque/money order for $_ _ _ _ _or please debit my: Card No. ~ ~I I'----'----'--____,I I I ~I~~ Signature _ _ __ _ _ _ _ _ _ _ _ _ Card expiry date_ _ /_ _ Name _ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ _ __ Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ _ _ __ _ __ Postcode _ _ __ _ _ 0 Bankcard SILICON CHIP 0 Visa Card 0 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 : SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503 --------------------------- - 94 - 7 O July 1988 0 December 1988 0 May 1989 0 October 1989 0 March 1990 0 August 1990 x I I ----------~-- Calculations; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Electronics For Everyone - Resistors. April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. 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; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3; Coherent CW - A New Low Power Transmission Techniq1-1e. 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 Electrics; Facts On The PhaxSwitch Sharing Your Phone Line With A Fax Machine. August 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder - A ?-day Pro: grammable Timer; Introduction To Stepper Motors; GaAsFet Preamplifier For The 2-Metre Band; Modern 3-Phase.Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; Alarm-Triggered Telephone Dialler; High Or Low Fluid Level Detector (uses LM1830N); Simple DTMF Encoder (uses Texas TMC5089); Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669} ; A Guide To Hard Disc Drives. October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes (Uses BA 1404 And TDA?000) Pt.1; GaAsFet Preamplifier For Amateur TV; 1Mb Printer Buffer; 2Chip Portable AM Stereo Radio, Pt.2; Installing A Hard Disc In The PC; A Look At Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse); Super Sensitive FM Bug; Build A Low Cost Analog Multimeter; 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, Uses Texas TMS3477NL and 256K RAMs); UHF Remote Switch; Balanced Input & Output Stages ; National Semiconductor LM831 Low Voltage Amplifier IC Data; Install A Clock Card In Your PC; Index to Volume 2. January 1990: Service Tips For Your VCR ; Speeding Up Your PC ; Phone Patch For Radio Amateurs; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On High Definition TV; 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; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC; Digital Waveform Generation Using a PC; The Controls On A Model Aircraft. April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio ; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3 ; Simple Service Tips For Your Microwave Oven; Model Aircraft Aerodynamics; Active CW Filter For Weak Signal Reception . May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors; The Mazzie CW Transceiver; Waveform Generation Using A PC, Pt.3; 16Channel Mixing Desk, Pt.4; What To Do When Your Computer Goes Bung, Pt.1 ; Electronic Load For Checking Power Supplies. 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 Your Computer; What To Do When Your Computer Goes Bung, Pt.2. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; LowCost Dual Power Supply; Inside A Coal Burning Power Station; What To Do When Your Computer Goes Bung, Pt.3; Digital Waveform Generation Using A Computer, Pt.4. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Appliances; Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2; The Tube Vs. The Microchip (Two Shortwave Receivers Compared); 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; LowCost 3-Digit Counter Module; Voice Mail For Your Computer; Simple Shortwave Converter For The 2-Metre Band; How To Make Dynamark Labels. 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. November 1990: Low-Cost Model Train Controller; Battery Powered Laser Pointer; A Really Snazzy Egg Timer; 1.5V To 9V DC Converter; How To Connect Two TV Sets To One VCR ; Introduction To Digital Electronics; Simple 6-Metre Amateur Transmitter. December 1990: DC-DC Converter For Car Amplifiers; The Big Escape; Wiper Pulser For Rear Windows; Versatile 4-Digit Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; The Green CD Pen Controversy. PLEASE NOTE: November 1987, December 1987, January 1988, February 1988, April 1988, & June 1988 are now sold out. All subsequent issues are still available but stocks of March 1988 are now low. Order now if you want this issue. JANUARY 1991 95 BOOKSHELF Computers and Music: an introduction Computers and Music, by R. A. Penfold. Published 1989 by PC Publishing, Kent, UK. Soft covers, 138 x 216mm, 174 pages. ISBN 1 870775 07 4. This book is entitled "Computers and Music" but it could just as well have been "Computers & MIDI" because that is largely what it is about, as you would expect. It is written for people who know nothing about computers and so a fair amount of the book is solely devoted to talking about computer hardware. It is only when you are a fair way into the book (page 53) that MIDI gets a reasonable mention. There are six chapters in all, with their titles as follows: Computer' Bas- LCD capacitance meter - ctd from p.92 AC signal to drive it. The backplane is an AC signal running at about 55Hz in this case. If a segment is to go black, the segment input has to be out of phase with the backplane. If it is to be transparent, the segment has to be in phase so that the potential difference across the segment is zero. These circuit functions are provided by the 74C946 (IC3). Parts availability At the time of writing, no kit is 96 SILICON CHIP ics, Storage Media, Ports and Peripherals, Real Computers, About MIDI and Music Software. As well, there are three appendices: one is a glossary of all the technical terms in the book, the second is a listing of hexadecimal numbers, and the third is entitled "checklists" and is in fact a list of desirable specifications for computers and equipment to be purchased with musical activities in mind. Overall, while the book is reasonably good as a primer for anyone new to computers, it is not so good as far as musical applications and MIDI are concerned. It never quite comes to grips with the MIDI standard for example, and nowhere that I could find does it give the technical specifications for MIDI (ie, baud rate, data frames, number of channels), even though it talks about the MIDI specification in a number of places. And if you want to run a MIDI system with your Commodore or IBM clone, there is very little help. In conclusion, if you want a basic primer on computers and some background on musical applications, this book is OK but it certainly won't make you an expert. We received sample copies from Altronics (Cat. B-2210) and Jaycar Electronics (Cat. BP-1216) and the price is $19.95. available for this LCD version of our capacitance meter, nor do we expect that any kit supplier will provide one. Both the 74C946 and the 4½-digit LCD panel are available as stock parts from Dick Smith Electronics. All the other parts are stock items from most electronic parts retailers. A PCB artwork and layout plans are available for $1.50 including postage from the author. Finished printed circuit boards are also available for an additional $12. Send all orders, together with cheque or money order, to Barry Naujok, 7 Admella Court, Portland, Vic 3305. SC Computer Viruses: with anti-virus disc Computer Viruses, Jonathon L. Mayo. Published 1989 by Windcrest Books, Blue Ridge Summit, Philadelphia, USA. Soft covers, 232 x 189, 160 pages with 5.25-inch anti-virus disc. ISBN 0 8306 3382 0. Are you frightened of a virus getting into your computer and corrupting all your valuable data? If you are not, you should be, especially if you ever borrow a disc from a friend. It can happen so easily and your "friend" may not even know that the disc is infected. When it happens, you really do have problems. This book talks about the subject in easy to understand language and tells you the commonsense ways of protecting your computer from infection, before it happens. Mainly, the safeguard is to backup all your data and programs and then put write-protect tabs on all the original (master) and backup discs. That way, the computer cannot corrupt the backed up data if it does suffer an attack. As a bonus, the book comes with a floppy disc with quite a few antivirus programs on it. We did not have time to check it through and in any case, we don't have copies of virus programs (as far as we know)! Even so, a disc of anti-virus software could be very handy and so the book is well worth considering. Our copy came from Dick Smith Electronics and is priced at $49.95 (Cat. B 6052). SC mJ llilllEI mlfalfDlltEl[iDHIDlllDJllm[IDIIIDHDIIDI SUPER SPECIALS FOR JANUARY! BRAND NAME 360K 5.25" DISK DRIVES WITH 3 MONTHS WARRANTY e 1 FOR $69 e 2 FOR $120 e 3 FOR $165 e 4 FOR $200 FLOPPY DISK CONTROLLERS TO SUIT AT ONLY Will 8088 8088 8088 8088 8088 8088 80286 80286 80386 80386 80486 12Mhz 12Mhz 640K installed 12Mhz 1Mb installed 31Mhz 31 Mhz 640K installed 31 Mhz 1Mb installed 12Mhz 16Mhz NEAT 25Mhz Cache 33Mhz Cache 25Mhz Cache $129.00 $250.00 $300.00 $225.00 $335.00 $385.00 $350.00 $649.00 $1995.00 $2495.00 $109.00 $199.00 $235.00 $189.00 $279.00 $319.00 $299.00 $449.00 $1495.00 $1795.00 $4395. WAS XT Case 4 Drives 150W P/S AT Case 3 Drive 200W P/S Minitower Case 200W P/8 Maxitower Case 200W P/S $199.00 $299.00 $399.00 $499.00 WAS 880K Macintosh series 164K Apple 11E 164K Apple 11 Gs 720K Amstrad PC 1512/1640 1.44 Amstrad PC 2000 360K Amstrad PC 2000 1.2 Amstrad PC 2000 1.2 Amstrad Portable 720KAtariSt 360K/720k 40/80 Atari ST 880K Amiga 500/1000/2000 360K Amiga 500/1000/2000 720K IBM 1.44 IBM 360K IBM 1.2 IBM 1.2 IBM PS11 360K Toshiba/portables 1.2 Toshiba/portables WAS WAS WAS NOW 3.5HH 3.5HH 3.5HH 5.25 5.25 WAS NOW $329.00 $209.00 $229.00 $249.00 $309.00 $249.00 $249.00 WAS NOW $ 99.00 $245.00 $245.00 $299.00 $199.00 $79.00 $199.00 $199.00 $279.00 $149.00 We also stock a huge range of cables, adaptors, swithboxes and chips Call today for very competitive pricing. $199.00 $199.00 $299.00 $149.00 $179.00 $160.00 $169.00 $265.00 $69.00 $149.00 WAS Serial 1/0 Card 4 port Serial 1/0 Card 8 port Games card 2 port Parallel printer card Serial 2 port XT Serial 2 port AT Serial/Par/Games XT/AT 2Serial /2Parallel Multi 1/0 S/P/G/C/F XT/AT Proto Board with decoder Slot Extension Kit NOW $199.00 $1 79.00 $449.00 $429.00 $ 29.50 $25.00 $ 24.95 $19.95 $ 55.00 $35.00 $ 65.00 $40.00 $125.00 $62.50 $ 75.00 $50.00 $125.00 $99.00 $149.00 $99.00 $199.00 $149.00 MOUSE/ACCESSORIES WAS Mouse for PC/XT/AT/PS11 $119.00 Mighty Scanner $399.00 Sound Blaster $399.00 NOW $99.00 $379.00 $349.00 KEYBOARDS $379.00 $249.00 $279.00 $185.00 $285.00 $249.00 $299.00 $249.00 $299.00 $409.00 $309.00 $369.00 720K 1.44 4MB 360K 1.2 INTERFACE CARDS 101 Enhanced keyboard WAS $109.00 NOW $89.00 GRAPHIC CARDS Mono PC/XTIAT CGA VGA8 bit VGA 16 bit 256K VGA 16 bit 512K CONTROLLER CARDS FDC 360/720/1.2/1.4 x4 FDC 360K to 2.88Mb X4 FDC 360K INT/EXT x4 FDC 360/720/1.2/1.4 x2 · HDC MFM PC/XT HDC/FDC MFM PC/XT HDC/FDC MFM AT HDC MFM AT Co-Existant FDC 2 Drives TRY PC MARKETPLACE SUPERFAST MAILORDER - Plii[ (jfeeson 's $205.00 $499.00 $849.00 $649.00 $399.00 $699.00 $999.00 MEMORY CARDS $349.00 $249.00 $269.00 $269.00 $329.00 $329.00 $329.00 $399.00 $269,00 $299.00 $199.00 $299.00 $299.00 $329.00 $29,9.00 $329.00 $449.00 $349.00 $399.00 POWER SUPPLIES 150W XT Power Supply 200W AT Power Supply NOW 14" White/Amber/Green $239.00 $535.00 14" Philips CGA 14" Multisync VGA $899.00 $695.00 14" Colour VGA Olympia NP30 Centronics $499.00 $779.00 Olympia NP80/24 Centronics Olympia NP136/24 Centronics $1395.00 EXTERNAL FLOPPY DISK DRIVES 3.5 5.25 5.25 3.5 3.5 5.25 5.25 5.25 3.5 5.25 3.5 5.25 3.5 3.5 5.25 5.25 5.25 5.25 5.25 INTERNAL FLOPPY DISK DRIVES MONITORS/PRINTERS Memory card PC/XT 576k Memory card 2Mb AT Memory card 2Mb XT Memory card 32Mb XT/AT am card for Amiga CASES up to 2 driws of 360/720/1.2/1 .44 includes cables for both 5.25" and 3.5" drives NORMALLY $99.00 SUPER SPECIAL $49.00 SAVE $50.00 HURRY UMITED STOCKS UMITED STOCKS SO BE QUICKIII MOTHERBOARDS WAS NOW Sl4)p0rt WAS NOW $129.00 $199.00 $55.00 $99.00 $139.00 $175.00 $245.00 $220.00 $119.00 $99.00 $179.00 $39.95 $79.00 $99.00 $1 49 .00 $199.00 $199.00 $99.00 WAS NOW $109.00 $109.00 $249.00 $349.00 $449.00 $69.00 $99.00 $199.00 $225.00 $299.00 DEALER ENQUIRIES WELCOMEWRITE OR PHONE FOR FREE CATALOGUE PHONE OR FAX TODAY! PERSONAL COMPUTER MARKETPLACE Pty Ltd FREIGHT CHARGES PHONE (02) 418 6711 Include $10 wrth order for all normal rtems • heavy rtems, e.g. monrtors add $15. FAX (02)4186713 14 day money back guarantee Mail Order Address: Order by phone (use credrt card), by fax or by mail. P.O. Box 1100 Lane Cove Unless insurance is declined rt will be charged at 1% of total purchase. This is for your protection. NSW2066 PRICES CURRENT FOR MONTH OF PUBLICATION OR WHILE STOCKS LAST. e VISA SERVICE IS THE DIFFERENCE • SERVICE IS THE DIFFERENCE • SERVICE IS THE DIFFERENCE • SERVICE IS THE DIFFERENCE The Story Of Electrical Energy, Pt. 7 Tasmania, our smallest state, is renowned for its extensive hydroelectric power system. While the hydroelectric system has been the subject of controversy in the past, it uses no fuel and emits no greenhouse gases. By BRYAN MAHER Converting the energy of falling water into useful work is an age-old art. The water wheel has been known since about 200BC in the ancient world, where it was used to turn millstones for grinding corn. Water wheels can be up to 80% efficient and they are long lasting. Some are still going after 150 years of use. Early efforts to generate electricity by the energy of water from a high dam commonly used the horizontal shaft impulse water wheel, known as the Pelton. In this type, a high veloc- Inside Liapootah Power Station. This station is unusual because the alternators are mounted above the main floor level. More common practice is to have the alternators and their turbines below the floor. Commissioned in 1960, the three alternators are each rated at 27.9 megawatts. 98 SILICON CHIP ity stream of water impinges upon cup-shaped buckets mounted around the periphery of a large diameter wheel. One of the world's earliest hydroelectric generating stations was built by the Launceston City Council in 1895, almost a century ago. The South Esk River was dammed and a penstock (a large sloping pipe) carried water down to the Duck Reach power station. Originally commissioned with a capacity of 450 kilowatts, the station was progressively enlarged to 2.2MW by 1919. This plant was retired in 1955, after 60 years of continuous service. How the HEC started In 1909, an ambitious scheme to generate electrical power using water from Tasmania's Great Lake was privately floated by the Hydro-Electric Power and Metallurgical Company Ltd. Government concessions prompted an optimistic start in 1910 when a canal was dug from the lake to Penstock Lagoon, the headwaters of the future power station. Access and transport difficulties in this rugged isolated region were formidable, as no road existed to the power station site at Waddamana. Therefore in 1911, a 27km horsedrawn tramway was built to transport materials and machinery. Sawn hardwood was used for the rails which were laid over rough log sleepers. A number of creeks and one river, the Shannon, required the construction of wooden bridges. The tramway operated return trips every second day, with loads varying from 5-10 tonnes, pulled by a team of 15 Clydesdale horses , harnessed single file. Newly arriving workmen were required to walk to the power station site, a 2-day trek from Deloraine. The pay was 8 shillings per day, with a tent and strawfilled sleeping-sack Hydro electricity is the cleanest form of power available to the human race. While it looks quite modern, the power station at Tarraleah was actually commissioned over 50 years ago, in 1938. It uses six Pelton water turbines, each driving a 15 megawatt alternator. provided free. All excavation work was-done by the time-honoured pick, bar and shovel method. By 1914, costs had escalated and the private company appealed to the government for financial assistance. The Tasmanian Hydroelectric Department was then set up by the state to take over and complete the project which was finally commissioned in May 1916. By the following August, almost 2000 electricity consumers in Hobart were supplied from Waddamana. So successful was the venture that the station was expanded progressively. The level of Great Lake was raised 12.5 metres by the building of the Miena Dam. Seven extra machines were installed, raising the station's output to 49 megawatts, a considerable figure in those days. Between 1939 and 1949, an additional station, Waddamana B, was constructed next to the old plant. This new station contained four 12MW alternators, also driven by Peltonwheel turbines. In 1988, the old Waddamana A power station was made into a museum as a Bicentennial project. Hydro philosophy In comparison to fossil fuel burn- ing power stations, hydroelectric installations have many advantages: (1) The source of energy is free and wholly renewable, depending only on regular rain and snowfall. (2) Although hydroelectric schemes involve the considerable loss of trees when they are built, once they are operating they cause no pollution, emit no carbon dioxide nor other gases and therefore do not further contribute to the Earth's greenhouse effect. This factor alone strongly favours hydroelectric power generation. (3) Low shaft speeds (100-500 rpm) are usually used. Therefore, hydroelectric power stations are comparatively quiet. (4) The low shaft speeds are conducive to long machinery life. Many plants run successfully for 50 years and more. (5) Though in the past hydroelectric schemes were more costly than coal burning power stations, today this is no longer true. (6) Dams associated with hydroelectric schemes can be indispensable in river flood control. As well as saving lives and farm livestock, this gives big benefits in avoiding damage to property and crops. (10) Hydroelectric turboalternators can be started from rest, brought up to speed and synchronised on line in just a few minutes. Thus, hydroelectric schemes cope excellently with varying electrical loads over a 24-hour day. In this respect, hydroelectric machines are far superior to steam turboalternators which take many hours to come up to full power after cold start. Energy and efficiency The dammed water flows downhill via penstock pipes to the water turbine. Thus, the potential energy of water at a height becomes the kinetic energy of high velocity falling water (see Table 1). To give the greatest possible power output, designers aim for the greatest possible head. If the penstocks can drop vertically from a dam to an underground power station, water friction losses are minimised. Where terrain dictates penstocks running long distances down a mountain slope, some energy will be lost in pipe friction (turbulence). This fact places an economic limit on the distance from a dam down to JANUARY 1991 99 Inside Tungatinah Power Station, commissioned in 1955. This station uses five alternators rated at 25MW each and driven by Francis turbines. All that is visible here are the housings for the exciters and sliprings. the power station. The energy advantage of a high head may therefore be partly cancelled out by turbulent losses in long pipes. So instead of building one dam high up in a river's headwaters and one power station far down below, we often see a multiple installation. Many dams are constructed along the same river. At each dam, the water is piped through a power station to be returned to the river below the dam. Thus, the same water passes through many power stations, generating electrical energy in each. Hydroeiectric systems may then consist of six or more small or medium size power stations spread along 100 SILICON CHIP the length of a river. This contrasts with the coal-fired steam power station philosophy where economies of scale tend to concentrate one or two very large installations close to mines. The Derwent scheme An excellent example of the repeated use of the same water flowing downstream is the River Derwent system. In the upper headwaters, the Tarraleah power station was built in 1934/38, during the Great Depression. At that time, 25% of Tasmanians were unemployed. In the inaccessible mountainous regions of the upper Derwent, the first task was the building of an access road known as the "14 mile". For five months through winter and spring, labourers toiled, cutting a track from the old West Coast Road to the power station site. Tarraleah power development obtains its water from the upper Derwent catchment area. A weir was built to raise the natural level of Lake St Clair by 2.4m, which greatly increased the water storage capacity. The water released flowed down the Derwent, then via a canal and penstocks to Tarraleah power station. February 1938 saw the first three 15MW machines in operation at Tarraleah. Work then continued slowly on the installation of a further three units. All use Pelton type turbines which are shaft-coupled to low speed alternators. By 1951, the 6th generator was in operation, bringing the station capacity to 90 megawatts. To increase the water storage supplying Tarraleah, the Clark Dam was built in 1951. A second system of flumes and tunnels added in 1955 feeds water from the dam to the Tarraleah headstock at Mossy Marsh. The 67-metre high Clark dam, closing Butlers Gorge on the Derwent (downstream from Lake St Clair) forms man-made Lake King William which is some 42km 2 in area. These two lakes together can store 740 million cubic metres of water. Included in the Clark Dam structure is the small Butlers Gorge power station, where one Francis-type turbine drives a 12.2MW alternator. A very unusual situation evolved when the 125MW Tungatinah hydroelectric power station was built in 1953. This station is driven by water from a chain of six lakes fed from the Pine Tier Dam on the Nive River. As the Nive is itself a tributary of the Derwent, Tungatinah power station was built adjacent to Tarraleah. The exit tailraces from both stations enter the Nive river almost at the same point, though each station is driven by water from different catchments. From its confluence with the Nive, the Derwent continues down the mountain, the water flowing through a further six plants: Liapootah, Wayatinah, Catagunya, Repulse, Cluny and Meadowbank power stations. None of these plants on the Derwent system is very large, with capacities ranging from 12.2MW to ELECTRONICS WORLD JANUARY SPECIALS USED 'AA' 700mAH NICAD BATTERIES $ 0.50 TEMPERATURE CONTROLLED SOLDERING STATION $135.00 UNIVERSAL NICAD BATTERY CHARGER $ 29.95 Can do 4 at a time (AA, C, D, or 9V Nlcads) 40 CHANNEL AM CB RADIO $ 79.00 SMOKE DETECTOR $ 49.95 PIEZO SIREN WITH BACKUP BATTERY $ 59.95 Ideal for Car Alarms DIGITAL DISPLAY AM/FM STEREO CAR RADIO $ 49.95 PORTASOL GAS SOLDERING IRON $ 35.00 ARLEC SUPER TOOL KIT $ 69.50 LOGIC PROBE $ 35.00 SCANNER FANATICS FREQUENCY REGISTER OF VIC. $ 24.95 PHILIPS INFRARED REMOTE CONTROL $ 35.00 COMMON CATHODE 7-SEGMENT DISPLAY $ 1.00 VIDEO DUBBING KIT $ 15.95 ARLEC 2 SPEED CORDLESS DRILL AND SCREWDRIVER $ 69.95 This photo inside Tasmania's Waddamana A power station gives a graphic view of a Pelton wheel water turbine. Now turned into a museum, the Waddamana A station was the first built by the Hydro-Electric Commission. 125MW each. Nevertheless, the total output of all 10 stations exceeds 500 megawatts - all from the one river and its tributaries! sliprings seen in the photo. Like an iceberg, most of the machinery mass is out of sight below, with only the exciting generators visible. Vertical shafts Types of turbine Most modern medium to large hydroelectric generators use the vertical shaft construction. Tungatinah is an example, with five 25MW machines installed. Each has a Francis type water turbine installed deep in the bowels of the station. Above the turbine, but on the same shaft, is mounted the main alternator; in this case, still below the turbine room floor. Above the floor level are the exciters and main Three types of water turbines are in use: the Pelton, Francis and Kaplan. Which of these is chosen for a power station design depends primarily on the water head height available. A secondary consideration is the variation-of efficiency with load changes. The Pelton wheel, with many buckets mounted around the periphery of a large wheel, is the oldest. Modern Pelton designs apply the water through adjustable flow nozzles and 2-CHANNEL FM WIRELESS INTERCOM $ 89.95 SINGLE CHANNEL UHF TRANSMITTER KIT $ 18.00 SINGLE CHANNEL UHF RECEIVER KIT $ 34.90 VULTURE CAR ALARM KIT $ 39.90 INFRA RED NIGHT VIEWER KIT $239.00 TALKING ELECTRONICS ULTIMA FM BUG KIT $ 12.50 Mail Orders Welcome 30 Lacey St, Croydon VIC, 3136. Telephone: Fax: (03) 723 3860 (03) 723 3094 (03) 725 9443 JANUARY 1991 101 BNC PLUGS AND SOCKETS BNC MALE PLUG 1-9 10 ,99 100.. P10514 S2.50 '2.25 $1.50 ~ · ·· HEATSINK COMPOUND S.¥e • tmall tortune on OteN hHllink. thus " Direct tmpo,1" low proll .. le increasing overall toekets! PCB mounling sotmr tall . All tin plated phosphor bronze or berryffium and dual wipe for reliability. 10 ·~ 1()(). P10550 :- 1-? ULTRASONIC 10·~ 10('1. P105311$2.8512.75 $2.00 ~ BNC ·· SOLDER LESS TWIST ON PLUG 1·9 10 -99 100• P1os31 s2.so 12.2s 12.00 µ;-CANNON PLUGS ~{• 'i::_ ' AND 'SOCKEfs.::· ... ... ....... ... J-----------t Pt05l0 , BNC CRIMP PLUG . TRANOUCERS Designed to transmit at 40kHz (L 19990) and recieve at 40 kHz (L 19991 )with up to 20V 1/P on the transmitter. These units can't be heard so are ideal for TV remote control's , water level detectors, burglar alarms, motion detectors and information carriers as they can be either pulsed or used in a continuos wave mode. P105'!5 P10567 P10S68 P10569 P1O570 P10572 P10575 CANNON TYPE 3 PIN CHASSIS MALE P10862 $3.50 wire wrap sockets are tln•plated phosphor bronze. 1·9 10+ P10579 8 pin 1.50 1.40 P10580 14 pin 1.85 1.70 P10585 16 pin 1.95 1.80 P10587 18 pin 1.95 1.80 PI0590 20 pin 2.95 2. 75 P10592 22pln 2.95 2. 70 P10594 24 pin 3.95 3.50 P10596 28 pin 3.95 3.50 P10598 40 Din 4.95 4.50 1-Q 10+ L19990..... $3.15 '2.15 Receiver L19991 .... '3.15 '2.15 ,o. 100+ P10864 $3.95 $3.50 $2.90 , IDC PLUGS AND SOCKETS PCB MOUNTING SCREW TERMINALS MICROPHONE SPECS , Transmitting Frequency: 37.1MHz Transmitting system : Crytllll oscillation. Microphone : ESectret oscillation ~~::_~~~:~1~:~~ 9 Lod .0lmmensions:115x32x44mm Weight , 220grams A10452...............$99 Jf you have 2 or 4 compatable devices th ■t need to sh ■ re a third or fifth, then these inexpencived■ ta tranter will save youthe time and hassle of constantly changing c·at,Ies and leads ■ round . No power required · Speed and code trenparent Two or four position rotary switch on front panel. · Switch comes standard with female connector. RS232· 2 way ............... ......$39 AS232- 4 way ..... $59 AS232- X over .................... $69 AS232-.2 way auto .............$69 Centronics- 2 way ..............$49 Centronics- 4 way ....$69 Centronics• X over. .... $69 Centronics- 2 way auto ...... $79 termin1l1 IHtur1 intarlocling enda to form P 1 - $4.95 .$ 4.50 $3.50 any number of coneclione. Standard Sn- ap.ctng pN'W • P1os20 2 way ,.. 10. 1·9 100. .10.IO $0.50 $0AO • P1os2, 3way SO.IO $0. 7D $0.IO 10 . 100. . • DE9P 9 pin plug $2.95 $2.50 $2.00 · DA15P IS pin plug P: 2161 $3 ."50 $3.00 S2.50 . DB25P 25 pin plug P12166 «::::Ji P12170 16.50 '3,.IS $3.50 CANNON TYPE 3 PIN LINE MALE 10+ 100+ 9 PIN TO 25 PIN CONNECTOR .. COMPUTER · CABLES • Sia conductor sh;.k»d computer 1nt•rt•ce cab4e • m:metre D TYPE IOC SOCKETS ADAPTORS a pin aocke1 . OE95 1-9 The perfect solution ! Features gold plated pins X'fs668 089 Plug to 0B25 Socket X15669 089 Socket to 0B25 Plug. 10 . . 100 . P12167 $2.95 $2.50 $ 2.00 15 pin aocket . DAl55 P1 2169 $3.50 $3.00 $2.50 0B25 CONNECTOR ==I~ SPECIALS P10885 P10890 P10891 P10892 P1P10895 P10902 QUALITY 3MM LEDS . 1.. 1 - 100. Z10140(R) ....$0.15 $0.12 $0.10 Z10141(G) ....$0.20 $0.25 $0.12 Z10143(Y) ....$0.20 $0.15 $0.12 Z10145(0l ...$0.20 $0.15 S0.12 1.. Z10150(R)so,15 Z10151(G)$0.20 Z10152(Y) $0.20 1 s$0.70 to $0. 70 $0.80 $0.80 $0.80 S0.80 - --- PUP S1 .lJO SO.BO - - - - - - - - --1 8087CHIPS FLAfflftNG l.J;OS 1-9 10+ Z10159 $1.10 t1.00 8087•3 (4.TTMHZ) 8087·2 (8MHZ) 8087-1 (10MHZ) 80287-6 (&MHZ) 80287-8 (&MHZ) 80287-10 (10MHZ) 80387-16 (16MHZ) ===Ill RECTANGULAR LEDS 1·9 10-H 100+ 15c 12c 15c 12c 15c 12C 15c 12C •· :::;:: <=~zl, • :J ---------~ 20c 20c 20c 20c 80&387 •33 ~ I., TOGGLE SWITCHES l ·i 10-H $11010 O.P.D.T $0.90 SO.BO i11!1i1,1, 1 PANEL METERS GALORE NICAOS We have a great range of panel meters at great prices! 010500 010502 01051k 010510 010518 010520 010525 010530 010533 010535 010538 010540 010550 010580 MU45 G-1m A $12.50 MU45 50/50uA $12.50 Ml.US G-100uA$12.50 MU45 G-5A $12.50 MU45 G-1A $12.S°O MU45 Q.1A $12.50 MU45 G-20V $12.50 MU52E 0-1A $14.50 MU52E 0-5A $14.95 MU45 VUP $14.95 MU65 0-SOuA $16.95 MU65 G-1mA $16.95 MU65 Q.100uA$16.95 MU650-20V $16.95 Save a fortune on expensive throw away batteries with these quality Nlcads and Aechargers! Size Desc. 1-9 10+ 100+ AA 450mAH $1.95 11 .75 11 .50 C 1 2 A H $9.95 $9.50 $8.95 D 1 2 A H $9.95 H .50 SB.95 SUPER HORN TWEETER · Requires no crossover and handles up to 1DO Watts · Sensitivity : tOOdB/ 0.5 m · Frequency responH : 3kHz-3-0kHz Independence: 8 ohms . Size 96 m diameter Normally .... .... $12 .95 10+ S7.00 $9.SO '6.50 J----------~ P12171 Sil.50 $3.15 $3.5CJ $1~ot $1.00 $1 .00 $1.00 $1.00 $1.00 $1 .00 ~:= g:::: :::: ::: red 5mm REP GREEN YELLOW ORANGE OE9S DA1SP DA 1SS OA15C DA15P DA15S 0B25C 1 - 100+ $D.1D $0.1D ~$0.15 $0,12 ... $0.11 $0.12 1·9 10+ 2155 24-0V 6-15V 1A Ca t M12155 $8.95 $7.95 2156 24-0V 6-15V A2 Ca l M12156 $13.95 $12.95 2840 24-0V 9VCT Cat M12840 $4.15 13.IS MOSFET 2851 24-0V 12-6V CT 250mA SPECIALS CalM121151 $4.95 $4.50 2860 240 V 15VCT 250m A 1-9 Cat M 12860 $4.95 $4.50 2SJ49 $7.50 6672 24-0V 15 30Yc 1 A tapped 2SJ56 $10.00 Cat M16672 $12.95 $11.95 2SK134 S&.90 2SK176 $9.50 25 pin aodlet . 08255 each $8.95 ==19; Receiver freq : 37.1MHz Output feveJ:· 37mV(max) Receiving sys: Super crystal PNTERLOCKJNG ENOS) ~ - 10UALITY SMM LEOS condenHr Power supply:9V battery Range: 300 feet In open lletd RECIEVER SPECS, Th ■N CANNON TYPE 3 PIN CHASSIS FEMALE ,.g 10. ·.,oo+ : ( CRYSTAL LOCKED WIRELESS MICROPHONE & RECIEVER DATA (R:SFEi SWITCHES These quality 3 level 10. 100. $2.9$ $2.50 CANNON TYPE 3 PIN LINE FEMALE ..... ... .......... ... 18 pin .... 30< 22< 20 pin. 30< 25t 22 ptn 30< 26< 24 p6n 30< 26< 28 pin . 30< 40pin 35< WIREWRAI> IC SOCKETS ·Transmitter 1·9 ,.e . ... . ,., ,, ,,... 8 pin .. ...., 12< 14ptn. ...l!Of , 15< 16pin ... l!Of , K< Cat.No. De.crlption P10S16 S2.SO S2.2S $1.50 LEDS I ~a; LOW PROFILE IC SOCKETS effk:iency. 1·9 , sff&¥ He1t1ink comPQund is applted to the bHe and mounling studs of transistors and diodes. It maintains I positive he■tsink seal that improves he■t transfer from the device to the H11801l..10g .. .... $2.00 H11810.. 1 .... $14.95 BNC PANEL SOCKET IC SOCKETS ONLY .........., .........$9.95 ~~ ~I ' 10W HORN ."' SPEAKERS $8.90 White durable pl astic . 8 ohms Cat. c12010 Normally St 1.95 W12670 . CIC& IDC CENTRONICS 36 WAY PLUG & SOCKET • Plug P12200 Pl ■ lltlc bo•■ with pl■■lc $3.95 $3.00 $ 2.95 IOp• ■ nd H■ ll■ bla In s aim ■. y_., popula, fro profecta & very economkal •150x90x50ft'l'l'I 10+ • Sor:ket 80 • 80 1 25.4mm 12V DC . 1.7 Wan . 0.14 Amps 100. H10111 ..... $4.95 10 . T12469 ............ ...... $12.95 10+ tans only $11 .95 each ,oo. $3.95 $3.00 $2 .95 FANS Quality, tans tor uu in power $4.75 • 185 x 113 x IOnvn H1D112..... $5.75 '$5.25 • 130 l 68 l 41nvn H10113..... $2.95 · ,2.so • 83 l 54 l 28nwn H1D1 15 ..... $2.25 $1.95 • 120 l 65 l 38nvn H10120..... $2.95 $2.50 12V DC FANS . ELECTRET MIC INSERTS IWll h pins lo, easy boa10 ,ns~n ,,. ·c:a, C 10 ,10 , S1 .20 •OO • VOLTAGE REGULATORS BARGAINS Dffcrlptlon 7805UC 7812UC 7815UC 7905UC i mps. computers. hotspot 7'12UC cooling ale . Anywhere you nHd pl• nty ol air. 7915UC 2.ov • s,s·· T12461 ..,12.H 11 SV • •·•·· T12463 .. ,12.H 240V 3 t 2·· T12465 .. • 12.15 115V 3 , 2"' T12467 .. ·•12.15 78L05 78L12 LM324 555 741 1·9 10+ so.so so.so so.so S0.45 S0.45 S0.45 S0.55 S0.55 S0.55 s1 .oo so:eo S0.50 S0.511 S0,50 -40 to.30 "1.40 to.30 $0.40 $0.50 MAIL ORDER & CORRESPONDENCE (Toll ,,_ Sb1cdy POSTAGI! $1- $9.99. $10 • 24 $25$50 $ so. S0.90 <at> Po FREE PACK & POST ON ALL ORDERS OVER $25,00 IN JANUARY. EXPIRES MIDNIGHT 31-01-91. LFREE PACK & POST ON ALL ORDERS OVER $25.00 IN JANUARY. EXPIRES MIDNIGHT 31-01-91 . ...._ , IBM* CARDS ~ r O'I I • -.·······•·.· T"'"4 0 I T"'"4 Cf') ~ ~ c., A simple way of monitoring AS232 interlace lead activity. Interlace powered, pockel size for circuit The Fortran CPF Filtered Electronic ~8a5~~9nar~~:J ~eg.~a~~~ing . 2 spares. 24 switches enables you Spike Protector provides a protective electronic barrier for microcomputers. printers. telephone systems and modems electronic typewriters. audio and stereo systems and olher sensitive electronic equipment. The CPF provides protection trom dangerous eleclncal spikes !hat can c ause anything from obvious damage (like Immediate equipment failure) to less obvious harm that can draslicaRy shorten a system 's lile r-1 z 0 r-1 ~ CPF"s superior circuitry design and . semi conductor technology re sponds mstanlly to any.potentially damaging over-voltage. ensuring safe trouble lree operation CJ) ~ ~ >< IJ;J Additlonally. CPFs filtenng capab1hty helps eliminate troublesome and annoying interlerence. general hash cre.ated by small motors. fluorescent lamps. and the like that threaten the perlormance and shorten equIpmen1 life of unprotected electronic components. r-1 ··SPECIFICATIONS: Electrical rating: 220-260 volts (AC) 50Hz 10 Amp SpikelRFI Protection: 4.500 amps for 20mlsecond pulses. Maximum clamping voltage: 275V differential mode. ~ ~ ;::l Cat.X10088 z s z ~, r-1 I.I') N ~ ~ IJ;J $69.95 • Keeps your paper and print-outs· • ~~a~s~~i~1~~:er makes 11 easy SPECIFICATIONS: Connectors: 0825 plug on 80mm ribbon cable and 0825 socket . Indicators: Tricolour LED's tor TD . RD. RTS. CTS. DSR. CD . TC. RC. OTA. (E)TC. Jumper Wires: 20 tinned end pieces Power: Interface power. Enclosure: Black. high 1mpact plastic. Dimensions : 85 x 95 x 30mm X15700 g . $19.95 Surges and spikes are caused not only by lightning strikes and load switching but also by other equipment being switched on and off. such as fluorescenl lights. electric motors. fridge freezers. air conditioners, etc., For effective protection such spikes must be stopped before they reach your equipment . Simply ptu~ The Button into an outlet and it wlll protect all equipment plugged into adjacent outlets on the same branch circuit. The Button employs unique metal oxide varister technology and will dissipate 1 50 jo"ules of electrical energy. (nearl y twice that of · comparable surge arreslers .) SPECIFICATIONS: ~~,:~~;::~:::li~8~~ Voltage : 240V Nominal $36.95 .. . RIBBONS .. fiiiiiij~, COMPUTER PAPER Quality paper at a low price ! 2.000 sheets of 70 gsm bond paper . Cat.C21003 11 ,9 1,2·· Cat.C21005 15x W .... $41.00 $67.95 PRINTER RIBBONS TO SUIT: • CPBO, SXBO, DPBO. BX100. ex100. MB100 1-9 C22036 .. $19.95 KEYBOARD EXTENSION LEAD 5 Pin Din plug and socket • MXBO, FXBO, RXBO, FXBOO. MX70. MXBO, LXBOO 1·9 • MX100. FX100, RX100 ,L01000 P19038 .. ,...........•.... $9.95 1-9 .. NEW 1 The ideal solut1on I Features gold plated pins X 15668 089 Plug to 0825 Socket X 15669 089 Socket to 0625 Plug each $8.95 ~ ~ 10+ C22002 ....$19.95 $17.95 C22051 .. $13.95 9 PIN TO 25 PIN CONNECTOR ADAPTORS 10+ C22031 .... $16.95 $15 .25 $69.95 ~ 10+ $17.95 • LXBO 1·9 • C ITOH 8510·1550 1·9 DELUXE PRINTER STAND • Restores order to your work area w1lhout occupying ex!ra space • i::eeds and refolds paper under the printer aulomaI1cally • Ad1usIable paper deflectors en sure smooth flow o! paper • Made of mo\Jldcd plasI1c • Suitable for most printers 10+ $11.95 10+ $12.50 :'.:L ~ ~ anti-static rubberised top •Stallonary holder E- C • IBM · compat,ble 34 lo way edge • Lenglh O 5 metres ~ •~~;:::,~I: ~ 3½"" FLOPPY DISK DRIVE EXTENSION CABLE U I"\ : ~ fT1 ,.... ~ P19045 $99.95 SURGE BUSTER 6 PROTECTEO POWER OUTLETS =lputo:e:~!~ngeqs:irsopme , ~t, colour TVS, amplifiers, tuners, graphic eqoatl,e,s. CD • IBM · compai,01e ***** • D83 7 Male to 34 IDC connector ~~9<5;;·Smetres $99.95 2&4WAY CENTRONICS DATA TRANSFER SWITCHES Save time and hassles of constantly changing cables and leads around with these inexpensive data transler switches. These data switches support the 36 pin centronic interlace used by Centronics, Printronics. Data Products. Epson. Micronics. Star , and many olher printer manufacturers. • No power required • Speed and code transparent • Two/Four position rolary switch on front panel • Three/Five interlace connections on rear panel • Switch comes standard with female connector • Bale locks are standard 2 WAY (X 19130) 4 WAY (X19 135) only$49 only$59 et=.· A~ UV EPROM ERASER Erase your EPROMs quickly and. safely. This unit is the cost effective solution to your problems. 1, will erase up to 9 x 24 pin devices in complete safety, in about 40 minutes (less lime for less chips) • Chip drawer has conductive foam pad • Mains powered • High UV intensity at chip surface ensures EFROMs are thoroughly erased Without timer X14950 ................... $129 With built-in timer X14955 ...........•....... $159 Keep your computer and accessories frH ot dust and grime while not in use POCKET AUTO AB SWITCHES Serial model : MS-201 - Host-powered X19150 .............•....$79.95 Parellel model: MP-201 Protocol transparent X19155 .••...•..........•$89.95 C/", ~ only $49 DUST COVER • Pocket size, auto-scanning • Allows 2 PCs to share one Printer Mouoe 5¼""FLOPPYDISKDRIVE EXTENSION CABLE only $39 .... ... .:.:~.~ ...:~ \ . XT HD CONTROLLER $129 AT HD CONTROUER $199 RS232/ SERIAU CLOCK •••••.•.•••••••.•••••••. .. $511 MONO/ COLOUR CARDi9& MULTI 110....................... $99 512K RAM ...................... $59 DIAGNOSTIC ................. $8411 TTU PRINTER. ............... $89 RAM 2M AT EXTIEXP •. $225 BM AT EXT/EXP ••.••••.••• $325 ,u. LEADS r, . VGA 1MEG ......... $495 VOICE MAIL ................... $245 PRINTER CARD•.•.•......... $35 EGA CARD..................... $1 39 2 WAY FCO CONT. (360K) ........•.•..........•.•.••••. S411 RS232 SERIAU CARD ••••. ......................... 149 GAMES ....•... •.•. .....••••....••• $29 AT SIP GAMES ................ S35 4 WAY FDD CONT. (3S0·1 .44 M) ••••••••••....... •...:$129 2 WAY FDD CONT. (3G0·1.44M) •••.......••••.••.. .. $80 CLOCK CARD ................. S411 SMART DRIVE ADAPTER IDEIFDC .......... $89 SMART DRIVE ADAPTER IDE 1/0 IFDC .•• $119 p1aye"' etc RIPPER STRIPPER • 3 x Metal Oxide Vartstors (MOV) Remove ugly paper feed edges •MaximumclampingVottage: each MOY: 710 vol1s at 50 amps quicklyandcleanlywllhthis simn.l rttl d t ~=?.:.:.~=~.:~::.95 C21085.~.~.~ ..~.~·······$14.95 Only $24.95 RS232 GENDER CHANGERS • Saves modifying or replacing non-mating RS232 cables • All 25 pins wired straight through Cat· X 15650 Male to Male Cat X 15651 Male to Female Cat X 15652 Female to Female Normally $14 .95 each OnlY$8.95 MOTHERBOARDS XT 10M MINI ••.....•••.••••••.•••• $120 XT31M,_ _ _ _ _ _..,199 I XT 12M STO. SIZE.. ••••••••••• S199 SUNTEC AT12M. ...............$375 80386-25... .!!'~M~.... $2,695 8D386- 33 ••• 1!-!:~l'.'1!L.$2,995 RODIRVING ELECTRONICS SYDNEY: 74 Parramatta Rd Stanmore . 2048 Phone (02) 519 3134 Fax (02) 519 3868 MELBOURNE: 48 ABeckett SI. Phone (03) 663 6151 RS232 MINI TESTER • Male to female connectmns • All pin wired slra,ght through • Dual colour LED Ind1cates ac1tvIIy and direction on 7 Imes • No batteries or power requi red T.D. TransmI1 Data O.S.R. Data Set Ready A.O. Receive Data C D. Carrier Detect R.T.S. Request to Send O.T.A. Data Termmal Ready C .T .$. Clear to Send C at. X15656 Normally $39.95 s NORTHCOTE: 425 H,gh SI Phone (03) 489 8866 CLAYTON: 56 Renver Rd Phone (03) 543 7877 MAIL ORDER & CORRESPONDENCE: P.O. Box 620. CLAYTON 3\68 Order Hotline : 008 33 5757 (Toll free , strictly· orders only) lr,quiries : (03) 543 7877 Telex : AA 151938 Fax: (03) 543 2648 I MELBOURNE DEALERS MICRODOT 177 SPRINGVALE ROAD NUNAWADING. Pll.894 1255 GREENSBOROUGH COMPUTERS 87 GRIMSHAW ST (en, Howard et) Ph: 434 S1SS COPYHOL.D E 7 (YU-H32) • Adjustable arms allows. ea1y positioning • Copy a re■ 91 /2" x 11" • Sliding line guide • Clamp mounting BRISBANE DEALER VRC COMPUTER SERVICE 147 LUTWYCHE RD . LUTWYCHE, 4030 ADELAIDE DEALER M CROTRONCS C21062 ••.....•••. $39.95 305 MORPHETT ST ADELAIDE, 5000 All sales tax exempt orders and wholesa~ inquiries to: RITRONICS WHOLESALE . 56 Renver Road. Clayton Phone: (03) 543 2166 (3 lines) Fax: (03) 543 2648 PRINTER LEAD Suits IBM• PCIXT, compatibles • 25 pin "O" plug (computer end) to C entronlcs 36 pin plug SPECIFICATIONS: . Electrical rating, 240V /1,C, 50Hz, 10A XT' Cover Set C21066 .......•......•... $14.95 AT' Cover Set C21068 .•..•.............$16.95· CENTRONiCS GENDER CHANGERS • Female to Female . • Saves modifying o r replacing non-mating Cenlronics cables • All 36 pins wired straight through . Cal . X15663 Male to Male Cat . X15661 Male-to Female Cat. x15664 Female to Female _Normally $33.95. 4 PORT SERIAL •••.••... .•••• S89 VGA 2561<. ••••••••••••.....••••. S199 VGA 512K....................... $299 SPECIAL. ONLY $32.95 C~1 •Includes pull-out shelf tor ~ 2'~m;~e ~°;;7;~~~r20 4 WAY Cat.X 19125 I $69.95 C21058 (80 column) •High qu.iity ABS plastic and 0 • Two/Four position rotary switch on front panel • Three/Five interface connections on rear panel • Switch comes standard with NATIONAL PANASONIC KXM110 PRINTER RIBBON C22034 ............ :.....$19.95 A working bench tor your Mouse. z • No power required • Speed and code transparent DUST COVERS MAGIC STAGE < RS232 DATA TRANSFER SWITCHES If you have two or lour compatible devices that need to share a third or fifth, then these inexpensive data transfer switches will save you the time and hassle of constantly changing cables and leads around . . C22003 .. $12.95 ....,:.. -. 50 JOUies Protection Level : 350V peak to check on paper supply • Paper can be fed from the cen tre or the rear according to !he design of the p·nnte, • Removci.ble drawer which allows paper to be changed w11hout moving the pnnler • Retrac table reaI basket makes print-out collec tion fa st and convenienl • Suitable for mos! printers ~ ,._, 0 positions . ENCLOSED PRINTER STAND .. . .. ·- ~ f~;~~o~~W~!e Q~ CJ) 0 1 0 ~ nr~=~c~ ~ncir~~~fi - > 0 ~ IJ;J RS232 BREAK OUT BOX CPF CONTINUOUS POWER ALTER SPIKE ARRESTOR THE BUTTON SPIKE PROTECTOR l1~4~A~ II ··--···- .: .. .. • . metres 18 P1 9029.................. $ 14.95 3 • metres P19030 ...•..•• ••.•..••.• $1 9.95 •10metres P19034 $39 95 .•••.•..•.•..••.•• • Errors and om1ss,ons · · excep ted . Prices and specifications sulijectto COPY HOLDER (YU H33) :;,i;.a~\, .. ,,-..,.,,..,.,.,.,.;,...,..,, intem11iona1 BusM>Hs Macn,nes c~~bs~albase "AWe " • ;=°'~.,.;.~ •Copyarea9 ' ,.;"x11.. • Sliding tine guide '-~::z rei,ster&d . $39.95 vJ ~ Q ..... ~ ~ FREE PACK & POST ON ALL ORDERS OVER $25.00 IN JANUARY. EXPIRES MIDNIGHT 31-01-91. · J;"_R_J;'~ PAr'T< lr POCT ON AT f ovn:coc:...n,,-co c,:-,c: llft_I_~ T.A 11i.TT I A.D'-l r.vnn-.r.c ••n·, ... n,..TT'T' ... 1 n1 n1_ UHF HIGH GAIN ANTENNAS antenn existing systems triangu/ powder coated receiving elements ensures excellent UHF reception compared to other UHF antennas of similar size and price. Two models are available: the TVA14 for Band Four and the TVA 15 for Band Five UHF reception. Both models are supplied with back reflectors to prevent ghosting as well as a waterproof entry box designed to accept 75 ohm coaxial cable without the need for addittional baluns. They also have predrilled holes for securing the tilt adjustable metal mounting bracket in either a horizontal or vertical position. Imported and distributed by: ~ ELECTRONICS Available through the following retailers: Bemys. Bridgepoint. Military Road. Mosman. 2088. NSW. (02) 969 1966. Ritronics. 56 Renver Rd. Clayton. Victoria. 3168. (03) 543 2166. CHRISTIAN BLIND MISSIQ~ ·d Re,8totiKf t~~~,, be1K COUPON Please cut and send to : CHRISTIAN BLIND MISSION INTERNATIONAL. P.O. Box 5, 1245 Burke Road. KEW. Vic. 3101 Phone: (03)817 -4566 D e Please send me further information about CBMl's work. As long as it is possible for me, I will help: D monthly D quarterly D annually D to prevent blindness D to restore eyesight D to rehabilitate the blind Enclosed is my gift of$ _ __ _ __ Mr; Mrs . Miss, s,~~t, .. . City, 104 SILICON CHIP Devils Gate Dam in flood. Measuring 84 metres high and 1,34 metres long, this concrete arch dam was built in 1969. Water from the dam feeds a Francis turbine which in turn drives a 60 megawatt alternator. are used with water heads of 200 to 2000 metres. Pelton wheels may be used with vertical or horizontal shafts. The Francis water turbine , used exclusively with vertical shafts, is suitable for water heads from 35 to 550 metres. In this type, the water is admitted via a spiral casing and circulates around the turbine rotor while falling to the tailrace directly below. The water's momentum is thus transferred to the rotor which in turn drives the alternator above. When the electrical load increases, more water is admitted to provide more power. Because of the water's pathway, partly circular and partly downwards, the Francis is called a mixed flow turbine. This appears to be the mostused type worldwide, probably because many dam systems yield head in this range. The Kaplan water turbine is almost identical to a ship's propellor mounted on a vertical shaft. Water is admitted to a chamber above from whence the water falls vertically through the propellor blades, so turning them. This type is used for small heads up to about 60 metres and is preferred in 'run of the river' systems. In these plants, the aim is to maintain the river flow rate. This is often necessary to meet irrigation and city water supply requirements, or additional hydroelectric power stations further downstream. The use of variable pitch blades in the Kaplan turbine allows the power produced to vary according to the electrical load, without changing the water flow rate. In-the Derwent river system, Kaplan turbines are used only in the downstream Repulse, Cluny and Meadow- ---------- ------1·-------- --! l _____J 2 8 ----=-----=--- --==--==-----==--- This cross-sectional diagram shows a "run of river" power station driven by a variable pitch Kaplan turbine. Variable pitch turbines allow the river flow to be maintained at a constant rate. The key to the diagram is as follows: 1 - water turbine; 2 - normal level of water on upstream side; 3 - water turbine pressure oil unit; 4 - alternator; 5 - indoor switchgear; 6 - transmission line to the outdoor step-up substation; step-up transformer; normal level of water on the downstream side. bank power stations. The latter is only 50km upstream from Hobart city which demands a continuous and ample water supply. By contrast, Francis turbines are preferred in the mountains where water heads are generally higher. Also in these power stations, the water flow rate can be adjusted as the electrical load demands, as ample water storage exists downstream. Efficiency Water turbine efficiency varies with the electrical load on the driven alternator. The Francis turbine is the most efficient at full load but shows poor efficiency at low load. Table 1: Power Generated By Hydro Stations The power generated by any hydroelectric scheme is given by: P = DgWHE watts, where: P = electrical power output in watts D = density of water = 1.0t/m3 g = acceleration due to gravity= 9.81 m/s 2 W = water flow rate (in m3/s) H = head; ie, vertical height of dam water above the turbine (in metres) E = efficiency factor to account for energy losses due to: (a) turbulent friction in penstocks and turbine; (b) mechanical bearing friction;(c) electrical losses in generator and transformer. This reduces to: P = 9.81 WHE (kW) Pelton and Kaplan turbines exhibit top efficiency over a wide range, from 0.3 to 1.2 times full load. Fig.1 gives some indication of these comparisons. Underground power stations Tasmania first ventured into underground power station design and construction at Poatina, at the northern end of Great Lake. From this high water storage, over 1000 metres above sea level, a 6km sloping tunnel, a hillside penstock and a 153-metre vertical shaft carries water to the power station built deep within the mountain. The extra cost and work involved in burrowing through solid rock, cutting out a suitable cavern and installing large machinery is formidable. But this cost is offset by the energy gain due to the very great head of water and the reduced friction losses through using a short vertical penstock. Because of its high water head of over 800 metres, Poatina uses vertical shaft Pelton water turbines. Six turboalternators, each of 50MW capacity, were installed and commissioned in 1964. The turbine room, cut out of the solid mountain interior, is 91 metres long, 14 metres wide and 26 metres JANUARY1991 105 This view inside Tungatinah Power Station while an alternator undergoes a major overhaul shows the very large diameter of these machines, relative to their power output of 25 megawatts. Water turbine powered alternators are always very much larger than steam powered alternators because they run at much lower speeds. Steam turbines run at 3000 rpm (to generate 50Hz AC) whereas water turbines run at between 100 and 500 rpm. This means that their alternators must have many poles and therefore a very large diameter. high. Above run the heavy-lift cranes used during installation and maintenance. The outflow water from the turbines runs via a tunnel and an open cut channel to Brumbys Creek, thence into the South Esk River, eventually to be reused by Trevallyn power station 60km downstream. Poatina, contributing 300MW to the state grid system, is remotely controlled from Palmerston, 6km distant. Access to the power station is by a vertical lift shaft and a 1km long roadway tunnel. 100 To increase the available water storage for Poatina, the water level of Great Lake was 90 raised in 1981 by increasing the height of Miena dam by 6 metres. This rockfill dam, 28 metres high and well over a l 80 kilometre ' long, contains c..,> nearly half a million cubic ;:;i::i metres of solid material. The ~ 70 present capacity of Great Lake is over 3000 million cubic metres of water. 60 106 SILICON CHIP 50 h/1/ --" ,,,,. 'I r/ ~ ~ "I Glacial lakes :r'he Tyndall Ranges, 800m above sea level, enclose many glacial lakes at approximately 500 metres elevation. The Anthony River drains this area before plunging down through a gorge to 240 metres elevation. This is one of the state's wettest areas, with rainfall averaging 3800mm annually. The catchment will be held in Lake Anthony by a 47-metre high concrete-faced rockfill dam. A pressure tunnel 5.5 metres in diameter and 7.5 kilometres long will carry the water down to the new Anthony underground power station. With a water head of 267 metres, a single 86MW Francis turbine and alternator will come on line in 1991. Next month we will look at the Gordon River system, where Tasmania's largest hydroelectric machines were installed underground. I Mersey Forth system Between 1968 and 1973 , the Hydro Electric Commission brought into operation a system of seven dams and seven power stations which were all driven by the one river and its tributaries. This construction stretches from Lakes Rowallan and Mackenzie through Lakes Cethana and Barrington and Devil's Gate Dam. Finally, the water flows via Lake Paloona to the sea through Mersey Forth, near Ulverstone on Bass Strait. These seven power stations contribute a total of 308 megawatts to the state grid. Presently, construction is progressing on the Anthony River development in the Tyndall Ranges in north west Tasmania. A system of five small dams and one power station will generate 83MW. White Spur dam, rising 43 metres, will contain 140,000 cubic metres of rockfill with concrete facing. The smallest will be Henty, a 24-metre high concrete mass gravity dam. 0 Acknowledgements 20 40 60 80 100 120 LOAD(%) Fig.I: this graph shows the efficiencies of the three type of water turbine, Pelton, Francis and Kaplan. Special thanks to the Public Relations Office of the Tasmanian Hydro-Electric Commission, to Liz Emson and ABB journal. SC 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. Increasing battery charger output voltage I am writing to ask for help with your DC-to-DC battery charger published in the September 1988 issue of SILICON CHIP. I have constructed the project to the letter twice and the maximum output voltage I can get is 11. 75V with an output current of 1.56 amps. I have checked and rechecked every step and still get the same results. On my first attempt at the project, I used a BUZ71L power FET which blew when the circuit was connected. On the next attempt, I used a BUZ71A with no dire results. I wondered if in the first attempt I could have damaged the PWM IC. When I connected a 20 watt 12V globe to the output and adjusted VRl for minimum current drain, the LED seemed to not really change, except that in the fully clockwise VRl position the LED goes off completely. I have put an ammeter in series with the globe and get only 1.57 amps - adjustment of VRl makes no difference. I have been battling with this project for two months now and would Queries on the train controller I first started reading your magazine because of the articles on electric locomotives and found them very informative and interesting. I don't profess to know much about electronics but am interested in model railways and from time to time have built up a few circuits which have been used in model railways. I very much like the controller featured in the November 1990 issue but would like to query one or two of the features: (1) All the way through the article and on the circuit, Q2 is given as TIP41 but on page 45 it is referred be grateful for any advice. (B.A., Croydon, Vic). • It is relatively easy to increase the output voltage of this charger circuit to the desired figure. The output voltage is a function of the internal 5V reference (pin 16), Rl, R2, R3 and R7. You can easily increase the output voltage by increasing R7 to 1 lkQ or 12kn. It's unlikely that you have damaged the IC or any other components. FM pickup on the AM stereo radio Thanks for publishing my letter praising the AM Stereo Radio in the September 1990 issue. The only problem that I have with it (there's always a catch) is that I live too close to the ABC tower for its liking. As a result, you are able to pick up ABC FM and JJJ if the headphone leads lie in a certain way. So, if you know how to cure this RF signal from getting into the headphone amplifiers, please let me know. I bet that you never thought that your design would pick up FM as well. to as a TIP32. Which is correct? (2) 200 square centimetres is an awful big heatsink. (3) The wiring for the tracking switch appears to be wrong. I think it should be the other way around with the outputs from the controller going to the moving contacts of the switch. Finally, a germ of an idea: is it possible to apply 12 volts DC uncontrolled to the track on a model railway and build the control equipment into the loco or wagon attached to the loco to be operated by remote control by radio or some other means? (R.H., Cape Paterson, Vic). • First of all, Q2 should be a TIP41. The TIP32 reference is wrong. 200 Perhaps it might be a good idea to publish an article on stopping RF signals from sneaking into anything electronic, especially hifi systems. (M.A., Gore Hill, NSW). • Being very close to the transmitters, it is not surprising that you have a problem with FM pick-up from the ABC towers. This should be cured by using a .0lµF ceramic capacitor directly between ground and the left channel output and a second .0lµF ceramic capacitor between ground and the right channel output. This should be done directly at the headphone socket. The idea of this is to shunt the interfering signals to ground before they enter the audio amplifiers. Don't use greencaps for this task; it is unlikely that they will work. What about a double stereo cassette deck? After talking to many friends, they all agree as I do that all the electronic magazines have produced many and various preamps and power amplifier combinations, but as we all know they are rack mounting. I have built square centimetres is not a particularly big heatsink considering that it is a single sheet. A conventional finned heatsink of the same effective area would be very much smaller. The wiring for the forward/reverse switch is correct. It can also be wired the way that you suggest, which is also correct. It is possible to have 12V DC on the railway tracks and have the control equipment built into the loco or wagon. This could be done two ways: either via radio control or command control which is a serial data system similar to that used on radio controlled cars. We hope to do something on this idea in 1991. JANUARY 1991 107 CD labels are prone to damage I have just finished reading the article on CDs and green pens in the December 1990 issue and must admit I found the whole subject intriguing. However, one point in particular I could not swallow. In one of the captions on page 16 you state that "A worse problem is scratches on the label which make the disc unplayable." Surely, you have made a boohoo on this point. (P.G., Lane Cove, NSW). • Nope, it isn't a mistake. It's true. When compact discs are pressed, they start as a blank of clear polycarbonate. This is then pressed with the master which puts in the microscopic track pattern of pits. Then, the pressing is placed in a vacuum chamber and a very thin layer of aluminium is sputtered onto what will be the label side. Then a clear lacquer coating which is cured under UV light is placed over the metallisation. Finally, the label is screen printed over the lacquer. So if the label is scratched, nine times out of ten the scratch goes through to the metallisation layer. Once that happens, the laser not only does not reflect from the mir- my own rack and so have lots of people I know. There is now a need for a good cassette tape drive including front door mechanism as a complete unit. Then you could design a rackmounted twin deck (cassette) recorder, so we can all have one, with simple no-nonsense controls, but of high quality reproduction. How about it? (no address - signature illegible). • No doubt it would be possible for one of the kitset suppliers to source a twin player mechanism and then we could design the electronics to go around it, as you suggest. We doubt whether many people would be willing to pay the price for the resulting kit though, as it is likely to be more than a fully built-up unit. There is another particular problem too, with kit-built cassette tape decks. We would naturally wish to include Dolby B and C noise reduc108 SILICON CHIP This photo shows the final step in the making of compact discs - the screen printing of the label over the protective layer of clear lacquer. If the label and the underlying clear lacquer are damaged, it is highly likely that the disc will be unplayable. ror layer but the very surface carrying the microscopic pits is damaged. In these cases, you can see right through the disc when you hold it up to the light. Where the damage to the label is minor and consists only of pit holes or fine scratches, the player will generally play the disc without problems although there will be interpolation errors. However, more severe scratches, especially those that go round the disc rather tion but it is not possible to simply buy Dolby chips. A licence fee has to be paid. That is an area that kitset suppliers would avoid. So really, a good quality cassette deck is unlikely to ever be a viable magazine project. However, we can't see why it would not be possible to rack mount a cassette deck. Some brands even have optional rack mounting brackets. Floppies in conflict I have a CCS IBM XT turbo clone computer and have been given a coexistent multi-format floppy drive controller card and a 1.44M 3.5-inch drive. The card has jumpers for 360K, 720K, and 1.44M and three different address settings. On first setting it all up, I could read and write to a 1.44M disc , and than radial scratches, can stop the player from even loading the disc. If you attempt to write on the label of a compact disc with any sort of ballpoint pen or a pencil, you are highly likely to damage the disc so that it becomes unplayable. This fact may not be widely known but it is true. So scratches on the undersides of your compact discs are bad enough but scratches on the label are far worse. format a disc as well, but often it would show a ridiculous number of bytes when you did a directory, like 99M for one file of only BOK, on a 1.44M disc. Now that's what I call cramming. Then out of the blue, it would not write to or format or CHKDSK but would read the 1.44M disc; then sometimes it would not read 1.44M but would read 720K. But the biggest problem is that, no matter if it is behaving itself or not, all the while the card is installed and whenever either delete button is pressed (by itself), the computer instantly resets itself as if you pressed alt-ctrl-delete, which means that if I want to use the 1.44M drive and card I can't use any software that uses the delete button and there is a heck of a lot that does use it. So far, I've only used DOS 3.1 but would DOS 4 be advantageous to solv- ing my problems? Could redefining my delete keys help and how do I do this? Can I change the addresses to help? (The three address jumpers don·t help). Are there any jumpers I could change on the original 360K card that would solve my problem? Can you tell me if there is a way to connect my XT directly to my brotherin-law's AT? Example: can I connect both, back to back, with a cable from serial port to serial port and would I need software to do this? Can you tell me where to get the necessary gear to link two computers and a rough price. (R.B., Port Douglas, Qld). •Unfortunately, we are not in a position to make detailed comments on hardware or software problems in computers. In general though, we can make the following observations: We think you have a problem with contention between your original controller card and the new multidrive card. Why not use the new card to control your existing floppies and the new 3.5-inch drive? It is possible to link two computers together using the RS-232C port but you will need commup.ications software to enable the systems to work. We suggest you contact your closest computer user club for more help with these questions. Remote control extender for VCRs I have a Yamaha RX730 Remote Control Stereo Receiver with remote speakers in the study and headphones in the bedroom, so when I read the article on the Remote Control Extender for VCRs in your September 1990 issue, I thought this is just what I need. I am very enthusiastic about getting this project to work but at the moment I'm stuck and running out of ideas. I bought the project as a kit from Jaycar. Assembly of the kit was no problem but when I first powered it up the 7808 regulator and Ql started getting hot so I checked for a short and found one. After correcting this, the circuit operated with LEDl flashing as expected. Testing the project (as a bare PCB) gives very frustrating results. At times the project seems to work but at other times it doesn't. Even when it works, it is nowhere Overkill on the alarm power supply Isn't the burglar alarm power supply described in the September 1990 issue a bit of technical overkill? I run my alarm from a car battery float charged to about 13V by a very simple trickle charger and this has proved reliable over many years. Since the battery must be able to supply the alarm anyway, what is the point of having a regulated mains supply as well? I don't mean to sound near reliable enough. From this point, I have done quite a bit of testing: (1). I borrowed a CRO from work and the pulses appear clean and square from ICl pin 9 through to the base of Ql. There is a slight degradation of the sharpness of the pulses (+ 7V) at the collector of Ql. I've replaced Ql but no change. (2). The power supply is OK, bang on +8V. (3). I've replaced IRLEDl but no change. (4). I noticed with the CRO that with a long twin speaker cable, there is 50Hz mains interference present. I've used shielded audio cable which reduced the 50Hz interference but doesn 't improve the performance of the project. (5). I disconnected the circuit that drives LEDl at A of DZ but no change. (6) . I've tested the project with my NEC N9033A Remote Control VCR, my Yamaha KX230 Remote Control Tape Deck and my Yamaha CD1050 Remote Control CD player, all with similarly poor results. (7). I've mounted the PCB in the small jiffy box as recommended with no improvement in results. (8). With the CRO, I measured the voltage drop across the 4. 7Q resistor as about 4V. This gives a pulse current of about 850mA which seems a little high for the specifications of the CQY89 (max IF of 50mA) so I put a lO0kQ resistor in series with the 4. 7Q resistor with no change in performance. So after all this testing I'm running out of ideas as to why the project doesn't work. All I can think of doing now is stripping the PCB and then re- churlish but I am interested in the rationale. (A.M., North Turramurra, NSW). • The alarm power supply has a number of features such as mains power dropout detection, a 12V supply and a charger for the backup battery. The supply also switches over from mains power to battery power without glitches to prevent false triggering the alarm. These facilities have made the circuit more complicated but we do not see it as technical overkill. building the project with new parts but this seems a little drastic. Can you help please? (R.T., North Rocks, NSW). • First, we suggest that you do not buy all new parts for the project since it is unlikely that there is any problem with the components themselves. When testing the Remote Control Extender, it is important that the unit is far away from the VCR or TV which is under control and preferably in another room. This is because the IR transmitter signal can otherwise be detected by both the VCR or TV and the Remote Control Extender, causing problems with reliable decoding. The Remote Extender IR LED should be located near the sensor of the TV or VCR for testing purposes. The 4. 7Q resistor which provides current limiting for the IR LED should be left at that value. The 50mA maximum current which you quote is for a DC driven LED. For our circuit, the LED is pulsed for about 15µs at a rate of around lkHz and consequently, the LED pulse current can be considerably higher. The 850mA used is well within the IR LED ratings. If the Remote Control Extender still is unreliable, we suggest that you remove the 56pF capacitor at pin 9 of ICl . This will allow faster rise times at the amplifier output. Editor's comment: this reader has since written to say that he was able to effect a cure by increasing the 0.15µF capacitor at pin 8 of ICl to lOµF. Apparently, this prevents an AGC effect which was reducing the gain of the circuit. We don't recommend this as a modification unless necess~ry, howe; er. JANUARY 1991 109 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. r-------------------------, FOR SALE CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads - $7.00 for up to 15 words plus 40 cents for each additional word. Display ads (casual rate) - $20 per column centimetre (Max. 10cm). WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" is a high resolution, shortwave weather fax, Morse & RTTY receiving program. Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same as RADFAX2 but suitable for Hercules, EGA & VGA cards respectively. $35. *** "SATFAX" is a NOAA, Meteor & GMS weather satellite picture receiving program. Uses EGA & VGA modes, needs EGA or VGA colour monitor & card, plus "WEATHER FAX" PC card. $45. *** All programs are on 5.25-inch or 3.5-inch discs (state which) & include documentation. Add $3 postage. ONLY from M . Delahunty, 42 Villiers St, New Farm, 4005 Old. Phone (07) 358 2785. Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your classified ad, print clearly on the lines below or on a separate sheet of paper & send the form together 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. CANNON PLUGS and receptacles, series MS & PT. Many types available. Send SASE for list to PO Box 87, Mt Evelyn, Vic 3796 or phone (03) 736 3445. THE FOLLOWING EQUIPMENT is now surplus to requirements: • 1 x HP41 0C voltmeter. 20Hz -700MHz with probe, operating/service manual, $350. • 6 x TF2002 Marconi signal generators. Solid state, AM/FM, 100mV-.01 µV, IIT MATHS COPROCESSORS Enclosed is my cheque/money order for $_ _ _ _ or please debit my O Bankcard 0 Visa Card 0 Master Card X I I I Signature_ _ _ _ _ _ _ _ _ _ _ Card expiry date_ __c/_ __ I I Name _ _ _ _ _ __ __ _ _ _ _ _ __ __ _ _ _ __ I I Street _ _ __ _ _ _ _ _ _ _ _ _ _ __ __ _ __ __ I I Suburb/town _ _ _ _ _ _ _ _ _ _ _ Postcode._ _ _ _ __ L _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI Card No. 110 SILICON CHIP ,,,. "1&):: ~,s, ,(-0 ~( 2C-08 2C-10 2C-12 2C-20 2C87- 8MHZ 2C87-10MHZ 2C87-12MHZ 2C87-20MHZ $330 $359 $430 $490 3C-16 3C-20 3C-25 3C-33 3C87-16MHZ 3C87-20MHZ 3C87-25MHZ 3C87-33MHZ $640 $680 $840 $990 ~&& These pices include Sales Tax. Stocks are limited at this price, so order early. PHONE (02)957 67 FAX (02)954 5550 r C CREATE YOUR OWN DIGITAL WAVEFORMS ·a, 0 C: .c MAX 1/0 Board Kit $169.00 Buitl & Tested $269.00 • 7 x Relays SPST 2 amps each • 8 x Switch inputs (TTL) • 1 x DAC (Digital to Analog converter) • 1 x ADC ( Analog to Digital converter) • 4 x Motor Drive outputs (40mA ea.) • 1 x Programmable timer output. MAX includes a 20 page manual with all schematics. parts layout etc .. a 360K PC compatible floppy with diagnostic and sample software in GW·Basic. MAX runs from a PC compatible Printer pert for full compatibility with a large range of computers. Same day dispatch of orders. Credit cards or personal cheque welcome. Phone: (08) 332 6513 or Fax: (08) 364 0902 (24 hours) (.) >< > ~ t- M ~ a. I-. Q) iii :: - Z ~ Cl C: (j) (D IC ,t- 0, (I) (.) (.) ,- -~ -g_ "O :5 -~ :: a. - 0 E §: CL 0 C-0 LL 0 r.: Cl) rE. M. Radvanyi, PO Box 49, Kingswood, NSW, 2749 -:I" ,,, in 0 u C) ci5 Money Order or Cheque Guaranteed delivery within 14 days -~ e -.::s:. C: 0 :.:; Software and PC Board $39.95 inc. P&P Software only $32.50 inc. P&P .J N IJl (I) As described in 'SILICON CHIP 'in March90, May90, June90 & July 1990. The software, can also be used for the similar project (simple PC function generator) described in Electronics Australia in January 1989. t- C'• Cl) :::J (I) I-. w in -:I" w ;::- (I) .J C/J C: .Ql 0. Cl) :::J (I) t- (.) C/J <( C/J 0 KIT REPAIRS Kits repaired from all magazines. PCs and peripherals also repaired Ring anytime 9am - 9pm EEM ELECTRONICS 1O Bouverie Place Epping Vic. 3076 (03) 401 1393 g 5IC s:. C o. cc TOROID POWER TRANSFORMERS From quality UK manufacturers. Available from stock at discount prices, 15VA to 625VA. Send SSAE for data & prices to: Transformer Discounters, PO Box 542, Wahroonga 2076. ACTIVE SHORTWAVE ANTENNA PC Computers 36 Regent St,Kenslngton, SA, SILICON CHIP, JAN 1990. Complete kit $59.00, Built and Tested $119.00, Case $10.00. MODEL TRAIN CONTROLLER project Silicon Chip November 19~0, $19.95 plus $2.50 p&p. Plugpack, 12VAC, 1.7A, suitable for the above (use rectifier), $29.95 plus $4.00 p&p. Kits built & repaired. Prototype production board supplier to the hobbyist & supplier of SILICON CHIP project PCBs. ELECTRONIC TOY SERVICES, PO BOX 491,-NOARLUNGA CENTRE, SA 5168. Phone: (08) 382 8919 FIX-A-KIT $20.00 PER HOUR LABOUR 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION Service to most types of electronic equipment TECHNICAL ASSISTANCE COMPACT INDOOR FM ANTENNAS Two models to choose from , Terk FM2000 a passive loop FM antenna for $69.95 or the Terk PI2 powered FM antenna with wideband low noise filter for $199.00. HYCAL INSTRUM.ENTS We can also provide assembly facilities for small production runs at competitive prices Design, Manufacture & Repair of Electronic Equipment Trading Hours 8am to 3pm, Monday to Friday JILOA (TECHNIKIT DIVISION) (02) 633 5897 10kHz-72MHz. Needs 24V DC regulated. Very good condition, $650. • 1 x Collins 51J4 communications receiver. Ready for restoration. Good condition, no mods, original. $500. • 2 x HP 1740A dual trace 100MHz oscilloscopes, 8x1 OCRT, 1mV/div deflection in x5 mode, selectable input Z, 3rd trigger view, copy of service manual. $1900. • 1 x Alinco DJ-SOOT UHFNHF amateur transceiver, with AC adaptor, nicad pack, book etc. $380. Handheld. • Brand new pocket size airband receivers. 118-136MHz, Japanese made, incl. rubber antenna, earpiece, 9V battery, frequency list. 12-months warranty. See review CB Action Jan/Feb 1991. $199. LOOP ANTENNA Improve signal strength & quality with this portable anlenna. Kit $44.00, Built and Tested $69.00 • Brand new UHFNHF mobile airband receivers. 60 memories, complete with telescopic antenna, AC adaptor, frequency list. 108-142.995MHz plus 220379.975MHz. 12-month warranty. As used by Japanese Air Ministry. See review CB Action Jan/Feb 1991. $429. Call, write or fax Av-Comm Pty Ltd, PO Box 386, Northbridge 2063. Fax (02) 949 7095. Phone (02) 949 7417 (answering service) . Mastercard, Visa, Bankcard welcome. WHOOPS! MY Z-80-BASED PBUFF printer buffer just doubled its memory capacity again. Over 3000 kits now sold. Combinations of DIP/SIPP/SIMM PO Box 73, Glenhuntly, VIC 3163. Telephone: (03) 571 6303 LEARN WITH UCANDO TRAINING COMPUTER ANIMATED VIDEOS VT201 53 Mins DC Circuits VT202 71 Mins AC Circuits VT203 54 Mins VCR Maint. VT204110 Mins VCR Repair VT205 47 Mins Semiconductors VT206 55 Mins Power Supplies VT207 54 Mins Amplifiers $75.42 $79.54 $75.42 $114.97 $75.42 $75.42 $75.42 MastercardNisa/NZ Cheque to: Electronics Assembly Company PO Box 21191, Christchurch, New Zealand. Phone (03) 79 5570 Price includes postage & packing. JANUARY 1991 111 MEMORY EXPANSION SIMM & SIP 9 X 256 9 x 1MB 8 x 1MB(MAC) 9x4MB -120ns -100ns - sons - ?Ons - 60ns -100ns - BOns - ?Ons - 80ns - ?Ons - 80ns N/A 23.00 23.80 24.70 30.00 79.00 81.50 89.50 76.50 82.00 528.00 -100ns - 80ns - 80ns - 80ns - 80ns 2.10 2.40 2.50 7.65 7.65 Prices At Sept. 13, 1990 CO-PROCESSORS INTEL 8087-2 80287-10 80C287-12 387SX-16 387DX-16 387SX-20 387DX-20 387DX-25 387DX-33 175.00 308.00 390.00 435.00 478.00 490.00 538.00 680.00 835.00 387SX-16 387DX-20 387DX-33 400.00 490.00 750.00 CYRIX 2MB 515.00 340.00 2MB 2MB 340.00 2MB 340.00 2MB 340.00 3MB 570.00 2MB 340.00 2MB 340.00 COMPAQ 386-20, 386-25, 386-20E, 386-S, 386-33 4MB MODULES 680.00 4MB BOArds 798.00 IBM PS/2 DRAM/DIP 4164 41256 41464 4 x256 1MB Advertising Index TOSHIBA LAPTOP T1000SE T1600 T3100E T3100SX T3200SX T3200 T5100 T5200 PELHAM WEITEK 3167-20 3167-33 4167-25 4167-33 820.00 1010.00 1500.00 1780.00 30/286,50 70E61,121 70A21 2MB 2MB 2MB 250.00 280.00 280.00 Sales Tax 20%. Overnight Delivery. Credit Cards Welcome 1st Floor, 100 Yarrara Road, Pennant Hills, NSW 2120. Tel (02) 9·9 0 6988 Fax (02) 980 6991 DRAMs in 9 memory sizes up to 2Mb. Rev J board, Ver. 4.3 EPROM & instructions $39. Cable board $9. P&P $3. Serial board & many other options available. Send 43c stamp for a free catalog to: Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. Phone (03) 338 6286. ANTIQUE RADIO ANTIQUE RADIO restorations. Your one-stop electronic repair shop. Specialising in restoring vintage radios including chassis rewiring, quality new parts, valves, valve sockets, speakers, transformers, cabinet restoration. Quality secondhand radio dials & parts for most brands & models. About 400 rad- ios in stock for restoration & parts. Every restored wireless is covered by a 2-year warranty on parts & service. French polishing of timber cabinets available. Vintage car radios in valve & transistor types available for restoration. Repairs done on tape decks, amplifiers, TVs & videos . Open Sat. 10am-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 AH. WANTED FOR WW2 ARN-7 radio compass restoration project: Control Box C4/ARN-7 and 22-pin female plug type PL-122. John VK3XAO (03) 736 3445 or write to PO Box 87, Mt Evelyn, Vic 3796. r-------------------------, SILICON CHIP BINDERS To: SIiicon Chip Publications, PO Box 139, Collaroy Beach, NSW 2097, Australia. Yes! Please send me _ _ _ $A3 p&p each (NZ $A6 p&p). x I SILICON CHIP binder(s) at $A 11.95 plus Enclosed is my cheque/money order for $_ ____ or please debit my 0 Bankcard 0 Visa Card 0 Master Card Card No. Signature_ _ _ _ _ __ _ _ _ _ _ Card expiry date_ _~ /_ __ Name _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ __ __ _ Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ __ __ _ Suburb/town _ _ _ _ __ _ _ __ ___ Postcode_ _ _ _ _ __ L - - - - - - - - - - - - - - - - - - - - - - - - -~ 112 SILICON CHIP Adroit Electronics .. ...... ............ 111 Altronics ................................ 28-31 Arista .. .. .. .. .. .. .. .. .. .. .. .. .. .. 45, 77, 104 Back Issues .......................... 94,95 Board Solutions ........... ... .... .. 46,47 Cad Connection .. ... .. .. ... ... .. ... .. 11 O David Reid Electronics ........ IFC, 1 78,79 Dick Smith Electronics ............ 8-13 EEM Electronics ...................... 111 Electronic Solutions .............. 19,85 Electronic Toy Services ............ 111 Electronics World .................. 101 Elmeasco ..................... ............. 51 Geoff Wood Electronics............ 65 Harbuch Electronics ................ 91 Hycal Instruments .................... 111 Jaycar Electronics ................ 53-60 Jiloa .......................................... 111 J.V. Tuners ... ................ ... .......... 75 M. Radvanyi ............................ 111 Oatley Electronics .................... 84· PC Computers .......................... 111 PC Marketplace .. .. .. ... .. .. ... .. ..... . 97 Pelham .. ................................ 112 Philips T&M .. ... ..................... OBC RCS Radio .. .. .. ... .. .. .. .. .. ... .. .. .. .. 27 Resurrection Radio ... ............... 45 Rod Irving Electronics .... ...... 38,39 70,71,102,103 Sheridan Electronics .. .. ..... ....... 21 Silicon Chip Binders .... ........ .. IBC Subscriptions ... .. .. ... .. .. .. .. .. ... .. ... 52 Sound Australia ..... ............. ...... 77 Transformer Discounters .......... 111 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Electronic Toy Services, 2/111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919. • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491 . Out-of-this-world performance at a down-to-earth price. The new 2900 Programming System brings the cost of high-performance programming down to earth. 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