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Fluke. First Family of DMMs. When accuracy, performance and value are important, professionals the world over look to Fluke - the first family of DMMs. Reliable Fluke-quality 3½- or 4½-digit DMMs fit every need - from design engineering to industrial troubleshooting. There's the low-cost 70 Series - the most DMM you can get for the money. The tough 20 Series - totally sealed and built to survive the dirtiest, grimiest, roughest jobs. The reliable 80208 Series - made to withstand the rig ors of the field service environment. The precise 8060A Series the most powerful and complete test and measurement system available in ii handheld package. And, of course, the versatile Bench/Portables that carry on the Fluke tradition for precision and durability in lab-quality bench instruments. Fluke comes in first again with the world's largest selection of quality accessories to help extend the capabilities of your DMM even further. There's no need to look anywhere else. Uncompromising Fluke design and leading edge technology are the reasons why attempts at imitation will never fool the millions of professionals that accept nothing less than a Fluke. FROM THE WORLD LEADER IN DIGITAL MULTIMETERS. IFLUKEI ® ELMEASCO Instruments Pt11. Ltd. Dealer enquiries welcome f aik to your local Elmeasco distributor about Fluke • A&..L.. John Pope Electrical (062) 80 6576 • J Blackwood & Sons (062) 80 5235 • George Brown (062) 80 4355 • ll.S..W. Ames Agency 699 4524 • J Blackwood & Sons• George Brown 519 5855 Newcastle 69 6399 • Auto-Catt Industries 526 2222 • D.G.E. Systems (049) 69 1625 • W.F.Dixon (049) 69 5177 • Ebson 707 2111 • Macelec (042) 29 1455 • Novacastrian Electronic Supply (049) 62 1358 • Obiat Ply Ltd 698 4776 • Petro•Ject 569 9655 • David Reid 267 1385 • Selectroparts 708 3244 • Geoff Wood 427 1676 • N.TERRITQRY J Blackwood & Son (089) 84 4255, 52 1788 • Thew & McCann (089) 84 4999 • QrNS~,N_f!; Auslec (07) 8541661 • G.Brown Group (07) 252 3876 • Petro-Ject (075) 91 4199 • St Lucia Electronics 52 7466 • Cliff Ele rorncs 1 55 • Nortek (Townsville) (077)79 8600 • l.E.Boughen 3691277 • Fred Hoe & Sons 277 4311 • The Electronics Shop (075) 32 3632 • Thompson Instruments (Cairns) (070)51 2404 • S.AUSTRALIA Protronics 212 3111 • Trio Electrix 212 6235 • Industrial Pyrometers 352 3688 • J Blackwood & Sons 46 0391 • Petro -Ject 363 1353 • TASMAWA George Harvey (003) 31 6533 (002) 34 2233 • VICTORIA Radio Parts 329 7888 • George Brown Electronics Group 878 8111 • G.B. Telespares 328 4301 • A.W.M. Electrical Wholesalers • Petro-Ject 419 9377 • J Blackwood & Sons 542 4321 • Factory Controls (052) 78 8222 • Mektronics Co 690 4593 • Truscott Electronics 723 3094 • WAUSTRALIA Atkins Carlyle 481 1233 • Dobbie Instruments 276 8888 • Protronics 362 1044 APRIL 1988 FEATURES 6 Vintage Radio: How it Began by John Hill Pt.2: the early days of broadcasting 10 What is Negative Feedback? by Bryan Moher Pt.1: Negative feedback & control systems 15 Arista 2-Way Loudspeaker System by Leo Simpson Good sound at a fair price 74 The Evolution of Electric Railways by Bryan Moher Pt.6 - The Sydney & Blue Mountains Systems 81 Digital Fundamentals, Pt.6 by Louis Frenzel Combinational logic circuits OUR NEW HEADPHONE amplifier lets you listen to your CD player direct, without degrading sound quality. Construction begins on page 28, PROJECTS TO BUILD 28 Headphone Amplifier for CD Players by John Clarke Low-cost design delivers excellent sound quality 32 Walkaround Throttle for Model Railroads by Leo Simpson Pulse power unit has inertia and memory 47 Build a Slave Flash Trigger by Greg Swain Simple unit for multiple flash work 60 A pH Meter For Swimming Pools by John Clarke Can also check fish tanks and soil acidity SPECIAL COLUMNS 16 The Way I See It by Neville Williams Audio power ratings - right back where we sta rted from 54 Serviceman's Log by the original TV serviceman Beating an intermittent when the heat's on 67 Amateur Radio by Garry Cratt Mobile antennas for the VHF & UHF bands DEPARTMENTS 2 Publisher's Letter 3 Mailbag 92 Product Showcase 94 Ask Silicon Chip 4 News & Views 96 Market Centre 50 Circuit Notebook THIS WALK-AROUND THROTTLE for model railroads features pulse power, inertia, braking, full overload protection, and excellent speed regulation. Details page 32. WHEN YOUR camera's f]ash fires, this simple project will automatically trigger a slave f]ashgun. See page 47. ~, / , '.\' .. . ·'·,· . .. "" " Making your-own antennas for VHF and UHF mobile operation is easy. Our amateur radio column on page 67 shows you how. A l'llll.'1988 ·1 SILICON CHIP Publisher & Editor-In-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Regular Contributors Neville Williams, FIREE, VK2XV Bryan Maher, M.E. B.Sc. Jim Yalden, VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA David Whitby Photography Bob Donaldson Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd . All material copyright (c). No part of the contents of this publication may be reproduced without prior written consent of the publisher. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd, Waterloo, NSW 2017 . Printing: Macquarie Publications Pty Ltd, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rates are currently $42 per year ( 12 issues) . Out-. side Australia the cost is $62 per year surface mail or $120 per year air mail. 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. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139 , Collaroy Beach , NSW 2097. Phone (02) 982 3935. ISSN 1030-2662 * Recommended and maximum Australian price only. 2 SILICON CHIP PUBLISHER'S LE'l-l'ER Those wonder£ul op amps; they're so versatile As you will have gathered by now, if you have been reading SILICON CHIP for a few issues, one of our major aims each month is to present electronic projects which appeal to enthusiasts with wide-ranging interests. And so it is this month, with projects aimed specifically at enthusiasts who have interests in railway modelling, photogi'aphy, high fidelity and chemistry. The latter refers to the pH meter which will be of use to people who have to maintain a swimming pool or fish tanks, or perhaps are keen gardeners. While we trust that the projects we present each month will hit the spot with readers who have specific interests, we hope that all the projects will be of general interest to a majority of our readers, merely because the circuits are interesting in themselves. · We get quite a kick out of developing these projects and consider it a challenge to get the best circuit performance for the minimum cost. For the last few weeks for example, we have been delving closely into the specifications of a number of "state-of-the-art" operational amplifiers as we develop a number of hifi-related projects. You will see the results of these endeavours over the next few months. While we were doing this research we also had occasion to review the performance of that relatively common quad op amp, the LM324. When you really look at it, this is a remarkable op amp; not necessarily state-of-the-art but remarkable nonetheless. Just consider: it can operate from single or dual supplies; it is directly compatible with logic circuitry; it has very low current drain, typically less than 800 microamps at 5V DC; and best of all, it is dirt cheap. "So what!" · you might say. Well have a look at the train controller and pH meter circuits described in this issue. By coincidence, they both depend heavily on the LM324. The pH meter uses all four op amps in one package in the same way, to obtain a circuit which compensates cleverly for the tricky parameters of a pH probe. And in the train controller circuit we use the eight op amps in two LM324 packages in four different configurations: three voltage followers, an oscillator, an amplifier and two comparators, with one interfaced directly to logic circuitry. We find it fascinating that it is possible to use such a common and cheap device (it only costs about $1.40) in such a variety of useful ways. The design of such circuitry might be way over your head but if you carefully follow the circuit description in these project articles you should eventually gain a good insight into how they work. For many people, this analysis of how circuits work is the real "buzz" of electronics; they don't wish to build 'em, just analyse 'em. Well that's great. You can enjoy electronics in a practical way by building projects; or by just reading the articles and analysing the circuits. There are few pastimes more satisfying. Leo Simpson MAILBAG Last steam loco I am finding your series on "The Evolution of Electric Railways" very interesting but I beg to differ on one point. You say the last steam loco to enter service in Australia was the Beyer-Garratt AD60 class No. 6042 in January 1957. In reality it was Queensland Railways 1089, built by Walkers of Maryborough, which entered service on 13th March, 1958. This loco is currently preserved in the QR Museum at Redbank, Qld. Graham Schultz Murarie, Qld You're right. We checked our references and found that, although this class, BB18-1l4, was introduced in 1951, the last one did not enter service until March 1958. UHF bow-tie antenna Congratulations on your new magazine. I have now placed an order with my newsagent for the regular delivery of it. The humorous illustrations in the Serviceman's Log are gems. Now for some critical comment: the construction article on the bow-tie UHF antenna [January 1988) is well illustrated and the quality of the drafting in the drawings is very good. The descriptive text is adequate and the discussion and recommendations on the use of highly corrosion resistant fasteners is a helpful inclusion. Likewise the listing of the required tools would aid the handyman who might be considering building the antenna. However, when discussing construction of the rear boom the article states' "make sure that all holes for the reflector elements in the rear boom are precisely in line and that their centres are 4.6mm from the front surface as specified on the diagram of Fig.2. This situation is much ·more easily said than done, particularly for a handyman with limited experience in metal-working. The 4.6mm dimension is theoretically correct but how does the handyman measure it? The best he is likely to have on a steel rule is 0.5mm graduations. Secondly, how does he ensure that the holes are not only in line but parallel with each other. If a drill press is used the holes will be square with the boom faces but if (as I presume) the electric drill quoted means a handheld unit, the finished result will almost certainly be disappointing. . I feel certain that your prototype antenna was drilled in a drill press. A drilling jig would also be useful for drilling the equally spaced holes. The drilling jig is not the only solution but I think your article should have particularly emphasised the factors which will influence the accurate drilling of the boom as this greatly influences the final appearance. The inclusion of the hints on drilling Perspex on page 49 of the same issue recognises the need to provide "how to do it information" in areas not familiar to handymen and I hope the trend continues. Fred Ray North Balwyn, Victoria We take your point. Our prototype was drilled in a drill press of the type available to suit many electric hand drills. Circuit success You published my letter seeking circuit information on Leak equipment in the January issue. I just wish to advise you of the marvellous response I have had to that request. I have received the circuit diagrams I asked about from a number of sources. Some people _took the trouble to ring me in order to check just what information I required. In one instance the information arrived anonymously. I was wondering if you could thank all concerned by a few lines in your Mailbag pages. Also I wish to thank you for publishing my letter in the first place. I rriust admit I am surprised at the interest in equipment of this vintage. John Sweet Aitkenvale, Qld More on the UHF antenna Your January issue featured the article on a 4-bay bow-tie antenna. The generous amount of background theory and competent coverage of all the issues makes for an uncommon delightful read, especially as it is not in an overly technical style, nor is it too long-winded. The attention to detail in the construction instructions is commendable but I think that the authors [in their zeal to make it seem easy for average handyman to build) have neglected to supply information vital to the extremely budget conscious constructor. For example, in the text it says that "the reflector is essentially a large grille about 60cm wide and 80cm high. SILICON CHIP, PO Box 139, Collaroy Beach 2097. The four dipoles are mounted on a common vertical boom which is spaced away from the vertical boom of the grille by about 50mm." While it is true that there is 50mm of air space between the booms, the air gap between the grille and the bow-ties is actually 72.6mm. Anyone not using the 19mm square tubing for the booms could be easily misled and build a much less efficient antenna. Please, please publish technical diagrams of all th·e relevant measurements in projects, not just selected measurements! I have seen antennas of this type with reflectors made of small aperture weldmesh painted with silver frost that used off-cuts of expanded aluminium for the bow-ties. Mounted on a flat piece of pine board hinged to a wall, the whole antenna installation cost about $5, including balun and cables. Another point: replacing the 17 reflector elements and the 19mm square tubing with a self-supporting aluminium painted steel reflector will reduce the cost of the project by well over 50%. Part of this saving can then be put to good use in buying 117th of a square metre of sheet aluminium to make the bow-ties. This would be easier than assembling your specified bowties. But again this is difficult because you have not provided any of the relevant sizes and angles of the bow-ties! To sum up, I feel that a magazine whose avowed purpose is to present electronics in an understandable format should present all of the data relevant to the project and then suggest a step-by-step procedure for beginners. B.Gennette New Lambton, NSW Your comment on the 50mm boom spacing has uncovered a blooper on our part. We experimented with a number of different reflector spacings before settling on the final figure presented in the diagrams. Many of these dimensions are a compromise, to gain the best performance over the whole frequency range of the UHF bands. We do not agree with your suggestions for economy. Anybody taking the trouble to build an antenna will want it to last for a long time. Nor do we agree with the suggestion of weldmesh or expanded mesh as it h~s higher windage (wind resistance} than the grille construction we have suggested. In very continued on page 49 Al'lllL '1988 3 NEWS&VIEWS Semiconductor laser emits visible light A semiconductor laser emitting visible light has been developed at Philips Research Laboratories in Eindhoven Holland. The laser, made of mix~ ed crystals of aluminium gallium, indium and phosphorus' emits light at a wavelength of 65_0nm and. ~s particularly smtable for digital optical recording. It has a peak power output of more than 100 milliwatts. Manning Valley Tourist Association spurns the local product Tandy kills 'em in computers Tandy has been well and truly hiding its light under a bushell as far as its computer sales have been concerned but now it has come out into the open. During 1986 in the USA, Tandy sold a total of 667,500 computers, including 272 ,000 machines operating with MS-DOS. This was a fraction behind Apple and well ahead of IBM's 457,500. During 1987, Tandy outsold Compaq in selling 403,000 PCs. In Australia, Tandy ha s an . established customer base in excess of 100,000 · and for the November/December period sold an impressive 1847 PCcompatible machine s . That 4 SILICON CHIP makes them well to the fore in Australia. This information was revealed at a recent press release to mark the introduction of three new computers from Tandy. The base model is the Tandy 1000 HX which has MS-DOS 2.11 stored in ROM so that a boot disc is not necessary. The second model is the Tandy 1000 TX, a PC/XT compatible running the 80286 processor at 8MHz and with a full range of options. The third release is a PC-compatible laptop machine with a very bright backlit "supertwist" LCD screen. It is equipped with 786K of RAM and runs at 4.77MHz or 7.16MHz. All three computers are on display at Tandy stores. Whatever many people may say about the waste of the Bicentenial celebrations, they have been good for. business. Not everybody's busmess has benefitted though. Late last year Manning Valley Tourist Association received more than two million dollars, mainly from the Greater Taree City Council and from the NSW and Australian Bicentenial authorities for the construction of an entertainment centre. Local hifi manufacturer ME Sound Pty Ltd thought this might be a good opportunity to tender with some of their professional gear. They made all the enquiries and went through considerable rigmarole but when it came to the crunch they were told that they need not bother tendering since the committee had decided on the purchase of a complete professional audio system of well-known Japanese brand. Now no-one would dispute the committee's right to make a considered decision to purchase equipment but since they are publicly funded, they have an obligation to call tenders and at least give those tenders fair consideration. It doesn't sound like cricket at all · does it? ' Philips and Sumitomo have magnetic agreement Philips and Sumitomo of Japan have concluded an agreement to make magnets from a new material made from a mixture of neodyium, iron and boron. Philips will market the material under the name Neodure. This material is currently the strongest known magnetic material in the world. It allows more powerful or compact magnetic assemblies to be built for consumer, automotive, industrial and telecommunications applications such as small lightweight motors, braking systems, measuring equipment and floppy disc drives. Prior to the development of Neodure, Samarium-Cobalt was the strongest known magnetic material and this will continue to play an important role, especially in high temperature applications. How to install a TVantenna the quick way Heard a good story about a major antenna manufacturer in Melbourne the other day. Seems this local yokel fronted up to reception and demanded to buy one of their antennas "at a good price" solely because he lived close by. They could not put him off and so eventually they sold him one of their top models for $150, a good deal more than he could have bought it at your favourite electronics store. He came back a day or so later, complaining that the antenna was NBG. They asked if he'd installed it properly. Yep, no problems. Where had he installed it? Right up on the chimney. So they went and had a look. It was up on the chimney alright, still folded up and in the plastic; no chimney straps, no cable, no nothing. Maybe the guy thought the signal gets down to the set by osmosis! Netcomm signs with Peter Brock Netcomm (Aust) Pty Ltd, the local success story in modem communications, has moved into the cellular communications market in a big way with the establishment of a subsidiary, Netcomm Cellular. This new operation will not only market cellular telephones but will also provide radio modems and portable facsimile machines. This means that high power company executives, particularly sales personnel, need hardly ever visit their offices. It is now possible to work entirely from the back of a car. In fact, cellular phones are now the new status symbol, particularly when they're fitted up in a smart ats tache case together with short whip antenna, modem and laptop computer or fax machine. Apparently taxi drivers are becoming quite used to the sight of a salesman flipping open his brief case and firing off a few phone calls while on the move. Makes sense, doesn't it? Guaranteeing the ABC's future The Minister for Transport and Communications Senator Gareth Evens has released a 4-page statement entitled "Guaranteeing the ABC's future". In it, there is a proposal to guarantee the base funding of the ABC and make it inflationproof for the next three years. The statement goes on to propose discussion on a new charter for the ABC because the Government is "firmly committed to maintaining a vibrant, strong, relevant and fearlessly independent ABC". After a lot more waffle in the same vein, you get the message that the Government is not really going to do anything with the ABC but they're backing away at 100 miles per hour from any proposal to cut the· ABC's funding in the next budget. Another statement released at the same time says that the Special Broadcasting Service (SBS} would receive its own Act of Parliament As a sideline, it would not surprise us if some smart entrepreneur produced a range of attache cases fitted with just the whip antenna, designed to impress the uninitiated. One of the beneficiaries of the R & D strength of the new company will be Peter Brock's BMW racing team. Netcomm Cellular will take over the development of the Racing Modem telemetry system first installed in the Netcomm team car which was a feature of the 1987 TV coverage of the James Hardie 1000 race at Bathurst. This system atso featured in a subsequent segment in "Beyond 2000". The deal also involves the development of EPROMs for the engine management of the BMWs in addition to new telemetry systems for engine development. Peter Brock also plans to have telemetry to monitor the casing temperature of all the car tyres so that imminent tyre failures can be spotted. and a distinctive Charter to secure its future as an independent part of Australian broadcasting. 50 years of amateur radio The Eastern Zone of the Victorian Division of the Wireless Institute of Australia will celebrate 50 years of amateur radio by holding a convention at the Mondarra Camp on the weekend of 13-15th May, 1988. Mondarra is a scenic locality in the hills to the north of Moe in Gippsland, Victoria. Activities planned for the weekend include foxhunts, QSL and CW contests, homebrew contests, childrens' competitions, performance checks on amateur gear and trade displays. Accommodation and meals will be provided for up to 100 people at a very reasonable price. For registration forms and more info, contact Bill (051} 27 7616, Stewart (051} 27 4229 or Chris (051} 27 5656. APRIL 1988 5 Despite initial problems, De Forest's Audion valve was to have a major impact on the development of radio. Regular broadcasts began in the early 1920s and, in Australia, scores of radio manufacturers sprang up to cater for the public demand. By JOHN HILL Last month, I covered some of the more significant developments in early radio - from Hertz' discovery of radio waves to De Forest's revolutionary "Audion" valve. We will continue where we left off. De Forest's early Auctions were not very good. The idea was great, but the implementation of the idea was let down by the valve not being made properly. It was soon discovered that radio valves required precision manufacture, with the placement of the various components being fairly critical. Another problem was that a sufficient degree of vacuum could not be attained within the glass envelope of the valve and the remaining gas interfered with its operation. Plate voltages in excess of 30 volts caused ionisation of the enclosed gases and the tube emitted a blue glow and ceased to function. Although the Audion was conceived in 1906, it was not commercially available until 1911. There were quite a few problems to sort out. The previously mentioned vacuum problem was solved by Arnold and Langmuir's research for better vacuums for electric light bulbs. Their independent efforts helped the Audion and a few other early valves along the way. During this early development period, the Audion's performance was pretty mediocre. It also faced strong 6 SILICON CHIP competition from the newly discovered crystal detector. The crystal detector was good for its price, required no batteries and didn't burn out. Crystal receivers were to become the poor man's radio for quite some period of time. Patent infringements There were other problems that De Forest had to face and one that caused him great frustration was the question of patent infringements. Marconi held the patent for Fleming's diode or twoelement valve, while De Forest held the patent for his recently discovered third element, the grid. Marconi claimed that De Forest's Audion infringed his patent but, at the same time, was himself unable to use De Forest's grid because of that particular patent. Both parties were in a bind. Apparently there was a brief period where attempts were made to sidestep these patents. Even valves with external plates were tried - anything to get over the opposition's patents. Eventually, everything sorted itself out. Lee De Forest had considerable foresight regarding the new science of radio and many of his ideas were well ahead of the times. He, like fellow countryman Reginald Fessendon, was interested in wireless This Kriesler radio of about 1948 vintage has survived the last 40 years quite well. It used a bakelite cabinet which is much more durable than plastic. telegraphy. As early as 1907, De Forest had devised a means of modulating a spark transmitter so as to broadcast speech. It must be realised that, at this stage of radio development, headphones were in use and the coherer was well on the way out. The US Navy placed orders for De Forest's unique equipment and it was sold with a five-mile (8km) guarantee. Actually, it had much better range than the guarantee promised. In 1908, De Forest gave a demonstration broadcast from the Eiffle Tower in Paris using his "Radiophone" transmitter. This historical broadcast was received as far away as 800 kilometres. Following up his success in Paris, the De Forest Radio Telephone Company began a series of broadcasts complete with singers and musicians. Two complete operas were broadcast and even the great Caruso sang in one of these extraordinary radio programs. However, impressive and all as these magnificent broadcasts were, they were mostly a waste of time for the simple reason that only a handful of amateur radio operators heard them. Once again, Lee De Forest was ahead of his time. Regular broadcasting was still about 10 years down the track, on the other side of the First World War. In the meantime, the American Telephone and Telegraph Company purchased the sole rights to De Forest's Audion and used it to relay long distance telephone messages. Radio was very much in the experimental stage during the first two decades of this century and both transmitters and receivers were few and far between. Even those who might have a radio receiver could only look forward to listening to occasional Morse transmissions. · ocean going vessels carried radio. As a result, the value of radio was brought to notice on several occasions. In 1909, the liner Republic rammed the Florida and began to sink. The wireless operator on the Republic radioed for help and received a quick response from nearby ships. All but six of the passengers and crew were saved. Such an incident did much to promote radio and bring it to the public notice. The above shipping mishap resulted in the American Congress passing an act requiring ships to carry radio equipment. Another shipping disaster occurred in 1912 when the Titanic struck an iceberg and sank in the North Atlantic with the loss of 1500 lives. Once again, the wireless operator on board the Titanic sent out a distress signal (in this case, the first SOS) which was picked up by the Carpathia. Although the Carpathia was quite some distance away, she arrived in time to save many survivors who would otherwise have perished. It is not generally known, but there was another ship much closer to the Titanic. Many more lives could have been saved if the wireless operator had been on duty at the time the distress signals were transmitted. This incident resulted in an amendment to the American Radio Act of 1910. The amendment required that ships have two radio operators on board so that a continuous 24-hour watch could be maintained. Broadcasts begin Back on dry land again, nothing much happened as far as broadcasting was concerned until 1919, when Dr Frank Conrad (an amateur radio buff and Westinghouse engineer) began broadcasting radio programs from a makeshift station in his garage. These programs consisted mostly of gramophone records and were very well received by other amateurs. Because of his regular broadcasts, Conrad received considerable correspondence and newspaper praise. Some of the local Pittsburgh papers even published transmission times. Had they Shipping disasters Ship to shore communication was the first really practical use radio was put to and a good many ships . were equipped with radio, even during the very early stages of its development. As early as 1910, most large You'll need a good collection of valves to start restoring vintage radios. These are still in their original cartons. Al'HIL 1988 7 This under-chassis view of a restored receiver clearly shows the wiring techniques employed. The major components were mounted directly on the chassis and the minor components (resistors and capacitors) strung between them. had some idea of the impact the coming radio boom would have on newspaper circulations, they may not have been so anxious to freely advertise Conrad's programs. One can only guess at the quality of the sound reproduction of Conrad's broadcasts. What with acoustic recordings played on a gramophone, it must have been little better than noise at the receiving end. However, such was the success of Conrad's regular backyard broadcasts his fellow Westinghouse colleagues decided to build a transmitter of their own at the Pittsburgh factory. It went pn the air in 1920 with the callsign KDKA. As far as American radio was concerned, KDKA was the real beginning of commercial radio and it grew at an incredible rate. In 1920 there was but one station; by 1924, there were 1400 stations. Now that's progress! The 1920s must have been the radio industry's boom time, for once broadcasting really got going, it became an immediate success. These early broadcasts operated at rather low power with most stations operating at levels well below 500 watts. 100 watts was quite common. With so little radiated energy, the ratio between static and signal strength was extremely high, resulting in distant programs being impossible to listen to because of interference from atmospheric and man-made electrical disturbances. The problem caused by static was gradually overcome by increasing the wattage of broadcasting sta8 SILICON CI-IIJJ tions. Such a move helped to tip the balance of the static to signal ratio more in favour of the listener. Broadcasting in Australia was not far behind the rest of the world and two stations were on the air towards the end of 1922. It was a repeat performance of the American scene and radio was readily received by an eager public. By 1930, there were dozens of stations on the air. Radios and radio components were all imported at first but this situation did not last long. Local manufacturers sprang up like mushrooms. Within a corn~ paratively short time, the Australia radio industry was in full swing and scores of radio manufacturers, both large and small, were producing radios from mostly Australian made components. Looking back to the turn of the century and the early development of radio, perhaps the most amazing aspect of it is the speed at which it all happened. It is also pretty obvious that it was radio that gave birth to the electronics industry as we know it today. Radio was the stepping stone to bigger and better things. Although the development of radio is just another frontier conquered, there seems to be something about radio that is difficult to explain. The fact that it works from afar without any visible connection between transmitter and receiver gives it a mystic quality. It is understandable why early researchers referred to it as "The Wonder of Wireless". Next month, we start collecting and restoring vintage radios. ic m . 1 Save a small fortune on these ·•Direct 1mporf' low prolile IC sockets! PCB mounting solder tail. Dual wipe. All tin plated phospho r bronze or berrylllum and d ual wipe for reliability. Cat. No. Des cription 1-9 10 .. P 10550 8 pin ...... .. . S0.20 $0 .15 P 10560 14 pin .. ... ..... $0.25 $0.20 P 10565 16 pin ... ...... . $0.35 $0.20 P 10567 18 pin . .. . .. . .. . $0.40 $0.30 P10568 20 pin ... ... .. .. $0.40 $0.30 BRAND NEW FANS Q uality, new fans lor use in power amps. computers. hotspot cooling etc. :~6vt-1£~?C~~11 ~~;f§11~95 11 5V 45,a·· Cat. T1 2463 $14.95 240V 3 1,2" Cat. T124o5 $14.95 115V 3 1,'2" Cat. T12467 $14.95 P10569 22 pin .. .. .. .. . $0.40 $0.30 10+ fans (mixed) only $ 10 each! P10570 24 pin ..... .. ... $0.40 $().30 P105 72 28 pin $0.50 $0.40 P10575 40 pin . .. .. , $0.50 $0.40 FAN GUARDS TO SUIT 45,a·· Cat T1 2471 $3.95 3 1,2·· Cat. T12475 $3.95 METEX M-3650 MULTIMETER 0 (with buzzer), capacitance meter. up to 20 amp current measurement and comprehensive ACIDC voltag e. current and resistance ranges CHECK THESE FEATURES .... • Pu sh-butto n ON/OFF switch . • Audible continuity test • ~~J~~:~~ts~7ici01~~i~Jf,~~o and RANGE selection . • Transistor test • • • • MINIATU RE HEATSINK ! Gold machined pins Exlremely high quality Anti-wickmg . Idea l for professional use o r where fi eld seNice of co mponents Is required. Cat.No. P10620 P 10624 P 10626 P10628 P10630 P1 0632 P10634 P1 0640 P10644 Description 1-9 8 pm $1 .20 14 pin $1 .60 16 pin $1.90 18 pin $2 .00 20 pin $2.20 22 prn $2.40 24 pi n S2.60 28 pin S2.90 40 pin S3.00 10 $1.10 $1.50 $1 .80 $1 .80 S2.00 S2.20 $2 .40 $2 .60 S2.70 • Diode test • Q uality probes • 112" High contrast LCD • Full overload protection • 20Amp £:~~c:;e;:><:>(%) (!!) C • lnstruclion manual N o rma ll yS 165 l, $0.35 WIRE WRAP IC SOCK ETS These quality 3 leve l wire wrap sockets are tin -plated phosphor bronze . Cat.No. P1 0579 AUTOMATIC CABLE STRIPPER 8 14 16 18 20 22 P10580 P10585 P10587 P10590 • Strips cable with diameler of t 1·6 2 2·6 3- 2rnm • Fully automatic action . Squeeze grip will simulataneously strip and eject insulation. • Lenglh 180mm {7") Description Price S13021 1 pol 2·12 pos. S1.95$0.95 S1 3022 2 pol 2·6 pos. $1.95 $0.95 S13033 4 pc; 2-3 pos. S1.95 $0.95 S13035 3 pol 2-4 pos. $1 .95 $0.95 Male to female 25 Detachable plug on leads 2 mini jumpers Ideal for experimenti ng or temporary connectio ns Cat. X15665 . .... Normally $49.95 Only $24.95 Only$44.95 Cat. T12500 ............. R.R.P. $149 SPECIAL, ONLY $129 P10592 P10594 P1 0596 P1 0598 Description 1 -9 1O , pin $1 .50 $1 .40 pin $1.85 $1 .70 pin $1 .95 $1 .80 pin $1.95 S1 .80 pin S2.95 $2 .70 pin S2.95 S2. 70 24 pin S3.95 S3.50 28 40 pin pin S3 .95 $4.95 S3.50 S4 .50 TEXTOOL SOCKETS P17016 16 pin .... .. ... .. .. .. $14.95 P17024 24 pi n ..... ..... .. .... $18.50 P17028 28 pin ..... ... . ..... . $24.95 P1 704040pin ..... ........... $29.50 HIGH EFFICIENCY RADIAL FIN HEATSINK H10520 105 x 30mm . Ht0525 105 x 75mm . $ 3.50 $ 4.95 H 10529 105 x 100mm . $ H 10534 105 )( 140mm . H10535 H10538 H10542 H10543 H10546 H10549 H10560 P11 000 P11005 P11007 P11009 P11 010 P11011 P110 12 P1101 5 P11 018 Price 100 Holes $ 2.75 640 Holes $10.75 640+ 100 Holes $14.95 640 + 200 Holes $17.50 1280 + 100 Holes $26.95 1280 + 300 Holes $32.50 1280 + 400 Holes $39.95 1920 + 500 Holes $59.95 2560 + 700 Holes $69.95 ADCOLA RS 3 01 2 WATT 105 x 150mm 105x 170mm 105 x 195mm 105 x 200mm 105 x 225mm 105x300mm 105 x 600mm 5.50 $ 7.90 . $ 8.90 .... $ 9.95 $10.95 $10.95 ... $11 .95 .. $12.95 .. $26.95 Special, only $32.50 ADCO L A RS60 2 1 WATT • 6.Smmlip • 240V operation . • 3 months warranty. • Safety Standards Approved . Cat. T12635 Normally $39.50 ~:g::~'.ng Only$9.95 ~ ~:-:.~ _ RS232 MINI J UMPER PATCH BOXES • Interface RS232 devices • 25 pin inputs • 25 leads with tinned end supplied • Com plete with instructions Cal . X 15653 Male to Male Cat. X 15654 Female to Male Cat . X 15655 Female to Female Normally $25.95 Only $19.95 DB15 GENDER CHANGER S •~:,r, sg D~~ii~5n~ : ~ r~~; ing non • AU 15 prn s wired sIra1gh t through X t 5645 : M a le to m a le X l 564 6 : Male to Fem a le X l 5 6 4 7 : F emale l o F e m a le only $14.95 Special, only $35.50 EJ • DB9GENDER CHANGERS • Saves modifyi ng or replacing non matin~ D89 connections • All 9 pins wired straight through Absolul13ly top quality. unlike our opposilion·s! 60140 Resin core'd. Cat.No. Description Price RECHARGEABLE 12V GELL BATTERIES T3 1000 .71mm 250gm .. ... $8.95 T31002 .71 mm 500gm ... $15.95 T3t010 .91mm 250gm . $7.95 T3 1012 .91mm 500gm ... $14.95 T31020 1.6mm 250gm ..... $7.50 T3 1022 1.6mm SOOg m .. . $13.95 T3 1030 .71mm 1 metre .... $1 .50 Cat. S15029 12V 1.2 AH $17.50 Cat. S15031 12V 2.6 AH $32.50 Cat. $15033 12V 4.5 AH $39.50 T3 1032 .91 mm 1 metre .. . T3 1034 1.6mm 1 metre ... • • • • ~ SOLDER SUCKER Light weight Sturdy construction Easy to remove tip EKce11ent value for money! ............... . $13.95 . SPECIAL, ONLY $ 32.95 R S 232 DIP SWITCH LEAD Better than an extra pair of hands! A must for all PCB work. Cat . T12444 ,I' . • . . ME LBOURN E: 48 A "Bpckett St . Phone (03) 663 615 1 NORTHCOTE : 425 Hlg~ St. Phone (03) 489 8866 CLAYTO N : 56 Renver Rd Phone (03) 543 7877 MAIL ORDER : Local Orders : (03 ) 543 7877 Interstate Orders : (008) 33 5757 All Inquiries : (03) 543 7877 COR RESPONDENCE : P.O . Box 620 , CLA YTO N 3168 Telex : AA 151938 Fax : (03) 543 264.8 - POSTAGE RATES : • Male to female connections • All pin wired straight through • Dual colour LED Indicates activity and direction on 7 lines • No batteries or power required T.D. Transmit Data D.S.R. Data Set Ready A.O . Receive Data C.D. Carrier Detect R.T.S. Request to Send D.T.A. Data Terminal Ready C.T.S. Clear to Send Cat . X15656 .. .. Normally S39.95 PC BOARD HOLDER • Rod Irving Electronics S1 ANTISTATIC SOLDER SUCKER Cat. T11 281 • MAIL ORDER HOTLINE 008 335757 fTOLLFREEJ /STR /CTLY ORDERS ONL YI LOCAL ORDERS &INQUIRIES f03J 543 7877 $1 ,25 $1.00 - Light weight Sturdy construction Easy to remove tip Excelle nt value for money! :r··:1~:e· _ ._·. only $14.95 Cat. T11271 ........... ........ $11 .95 • • • • ,'m , X 1 5640 : Male to male X 15641 : M a le to F e male X 15642 : F e m a le to Fem ale R S232 MINI TEST E R "'""':"""""' I Description ~i~~a~~i~~~hi' • • All 25 pins wired straight through Cat. X15650 Male to Male Cal . X1 565 1 Male to Female Cat . X15652 Female to Female Normally $14 .95 each ~i~fc~~e~n~ l~deu:1~:,,: :~~~ ilitary manufac ture , repair and rework ot ad vanced electronic circuits and other scientific equipment. SOLDER ROLLS ...... ...... .. ..... :. :::::::-:_:j Cat. No. RS232 GENDER CHANGERS ADCOLA RS501 6 WATT . .....""'""'"""" ,:::::::': '::J BREADBOARDS -~ . These are professional quality precision soldering tocls , similar to • Smmtip • 240V operation. • 3 months warranty • Safety Standards Approved . Cal . T 12630 . Normally $36.50 Leakproof and in 3 convenient sizes, these long service life baneries are ideal for burQular systems, emergency lighting or as a compu1er backup power supply. Ideal for many power needs . ECONOMY ROTARY SWITCHES use • Can he left on without fear of damaged tips! The best Is always worth havir:,g • • • • Special , only $32.00 $19.95 Tl 1532 RS23 2 WIRING ADAPTOR BOX x, • 3mmtip • 240V operation . • 3 months warranty. • Safety Standard s Approved. Cat T 12625 N orm.a lly S36.00 Designed by Rod IN ing . 1 Special , only $149 Cat. No. $0,40 Ht0606 ~!!ii~ ~~ l~ffj~,! ~;~nts ol heal for • Built in l1lt1ng bail 09 1550 . A grea! linle fellow ii you are short ol space. Great price too. because we import direct so you save! Dime nsions : 19(L) x 13(W) x 9(H)mm Cat.No. 1-9 10 ... Stack anodised with a thick base plate. this radial fin heatsink can -- ~-:..:, •_,_,.., ._. .., • Capacitance meter The WTC PN Features : • Pow er Unit 240 V AC • Temperature controlled iron, 24 VAC • Flexible silicon lead for ease of ADCOL4 SOLDERING IRONS GOLD INSERT LOW PROFILE IC SOCKETS capacitance meter and transistor tester. diode and transistor test continuity C HANGERS • Female lo Fem ale. • Saves modifying o r replacing non-mating Centronics cables. • All 36 pins wired straight through. Cat. 5663 Male to Male Cat. X1 566 1 Male to Female Cat. X1 5664 Female to Female Normally $33.95 , ~ ~~~;,~;~O:~?.i1~~~~~~7t~ ~~;f~c~~~a~a~u~i~i~~t":ellow :irr~~~~;g; ~~i~~;(\~2gJ~~~ts CENTRONICS GENDER WELLER WTCPN SOLDERING STATION • • • • 10 Way Dip Switch D825 ma le plug to D825 male plug Length : 2 metres Instructions Included Cat. P1 9031 . . . . . . . $59.95 S9.99 $10 S24.99 S25 S50 $49 .99 S99.99 $100 $199 S200 S499 $500 plus The above postage rates are for basic postage only. Road Freight. ~~~~~: ~:tt~~~~i~~~':'a~:i_ll be All sales tax e ampt orders and wholesale inquiries to : RITRONICS WHOLESALE. 56 Renver Rd. Clayton . Ph. (03) 543 2166 (3 lines) Errors and omissions excepted :~:a~~s ~T;n~~a~~~~~~~~~~s Machines •Apple is a registered 1rat1em,1r~ 'Denotes registered rradmar11 s o' :hrir respective nwners Pt.1: Negative Feedback and Control Systems WHAT IS NEGXI1VE Have you had trouble understanding the concept of feedback? This article tells the story of feedback irr simple everyday terms. By BRYAN MAHER Negative feedback systems are part of our everyday experience. They may be electronic, mechanical, hydraulic, pneumatic, nuclear, chemical, economic, logical, biological - almost any type. We are born with them, they control our bodies, the Sun and the stars, our domestic appliances, our motor cars, virtually everything. So we ought to have a simple description, an explanation, which is expressed in a language which every body can understand. This short series of articles aims to do just that. Once upon a time there was a little girl and her dog, a lovable mischievous hound, playful but quite adverse to washing. One day, after being all soaped up, the dog took off and jumped over the back fence at the sight of the rinsing hose spouting cold water. The little girl decided to hose down that squirming, frothy animal by squirting hose water high over the fence. Trouble was, she couldn't hit her moving target because the fence blocked her view. Then she hit on a solution. She enlisted the aid of her big brother to sit on the top of the fence and feed back directions to her. "Swing hose to left ... no, more left! ... too much! ... back some! ... a bit to the right ... lift hose higher ... too much! ... down a bit..." The farce went on as the dog, out of the little girl's line-of-sight, dodged back and forth in attempts to avoid the freezing hose water. At the same time, big brother found that both he and little sister had to be quick or · the dog could move Without negative feedback, modern amplifiers would not be able to give the superb performance that we routinely expect from hifi equipment. 10 SILICON CHIP away faster than the information could be fed back to hose-toting little sister! While it would never be referred to as such in a child's bedtime story, here was a negative feedback system in violent action. • The Input or Demand was the little girl's desire to hit the soapydog with hose-water. The Desired Output would be an image of the input demand; ie, a clean, wet dog. • The Actual Output was the hosewater missing the dog and landing on the ground (ie, the feedback system was not fast enough). • The hose itself and the water it carried was the dumb power or energy input. • The Negative Feedback was the information fed back by big brother sitting on that fence. • The Error was the difference between the spot where the hosewater landed, and the spot where it should have landed. That last statement could be stated concisely as: Error = (Desired Output Actual Output) Now the Desired Output is an image of the Input Demand. And the Feedback Information is an image of the Actual output. The Actual Output cannot be "seen" by the system. Feedback becomes the only indication to the system of what's happening at the output end. So, best results come when the system is working to make the Feedback and the Input Demand coincide (which implies that the Actual Output and Desired Output also coincide). In other words: Error = (Input Demand Feedback) = Zero Now, because Feedback appears in that equation as a negative, we call it a Negative Feedback System. We say that the "forward Autopilot In a Yeppoon fishing boat, the auto-pilot control system may be instructed to keep the boat heading east to reach Keppel Island fishing reefs. Here the input is "Direction East'', the controller is the direction sensing and correction circuitry, the actuator is the hydraulic ram system pushing the rudder into position, and the output is the direction the boat is actually heading. In an Ft 11 fighter airplane, the pilot may insert an input instruction "fly to Keppel Island coordinates" into his Inertial Navigational System, a remarkable electromechanical-hydraulic control system. Here the first input is the pair of co-ordinates which describe the position of Keppel Island (the pilot inserts these numbers using digital switches). Other inputs include: (a) Reference position coordinates before he starts. (b) Inputs automatically inserted to describe the Earth's pear-shape; (ie, it is · bigger in the southern hemisphere). (c) Inputs automatically inserted to describe the Earth's bulge around the equator. (d) Inputs automatically inserted to de.s cribe the effect on the plane of Coriolis force. (e) Inertial references to the "fixed" stars of the universe by way of electrically-driven captured gyroscopes. The controller in this case is an electronic analog computer, while the actuators are the hydraulic rams controlling the wing, tail and FEEDBACK? system" from the Input to the Output, plus the "returning feedback information pathway" from the output back to the "front end" makes a "closed loop". Thus, Negative Feedback Systems are known as Closed Loop Systems. Later, when big brother tired of the game and departed to ride his skateboard, little sister could only squirt the hose in a hope-for-thebest sort of action, simply applying the Input but not being able to correct to bring the error to zero. Naturally, the results were pretty awful. This last condition, without any feedback path closing the loop, is (not surprisingly} known as an Open Loop System. Our wet-dog story vividly illustrates all the features of every Closed Loop Negative Feedback System. Alternative names used are "Automatic Control System", "Feedback Control System", or just "Control System". All mean the same thing. These days, electro-mechanical and electro-mechanical-hydraulic control systems are everywhere. If the Feedback Control System is purely electronic, and all components and actions linear, we would simply call it a "Negative Feedback Amplifier". All hifi audio amplifiers fit into this description. Essential parts The Feedback Control systems we meet may be fairly simple, or they may be extremely complicated but usually we will be able to identify the essential parts as in Fig.1: (1} Input. Sometimes called the command or demand, there may be more than one input. Sometimes we must be careful to define exactly what is the input. The input is the definition of what we want done. (2} Controller. The brains of the system, the controller may be anything from a simple electronic amplifier to a complex electrohydraulic system controlled by a computer. (3} Actuator. The muscle of the system, the part that actually does the work. It may be a single output transistor, or the power output stage of your hifi amplifier, a hydraulic ram, a 20MW electric motor or even a two-gigawatt power station. (4) Output. Supposed to be the obedient servant of the input. Hence the common name Servo System (the word servo is a Latin word meaning slave). Sometimes the term MasterSlave System is also used. As with the input, sometimes it is not quite obvious exactly what is the output. And there may be more than one output. If one of the inputs is a carefully maintained constant it is often called a reference. If the input command is to keep the output quantity level always, the whole feedback system is usually called a regulator. Let's have a look at a few examples of Negative Feedback Control Systems. INPUT CONTROLLER - ACTUATOR -- OUTPUT Fig.1: the essential elements of an open loop control system. There is no feedback path from output to input. - INPUT- CONTROLLER ACTUATOR OUTPUT FEEDBACK TO CONTROLLER OF INFORMATION ABOUT OUTPUT Fig.2: a closed loop control system. In this system, information is fed back from the output to modify the controller action. Al'HIL 1988 11 BUILDING UNDER CONSTRUCTION BUILDERS SCAFFOLD Builders and bystanders GEAR WHEEL ----, MOTOR WINDING DRUM H01ST AT GROUND LEVEL I I Fig.3: a simple motor-driven hoist. With this scheme, it's difficult to operate the on/off switch to stop the hoist in the correct position. table, the Input is the instruction "keep the turntable speed exactly 33-1/3 RPM". The controller is a complex electronic circuit which includes frequency to voltage converters. The Reference is the frequency of a crystal oscillator, the Actuator is a DC motor mounted directly on the turntable shaft, the Output is the actual rotational speed of the turntable. As we want the output to be a constant always, we might call this control system a "speed regulator". rudder surfaces. The output is the aircraft's arrival position. The result is remarkably accurate the plane will pass over the island and if further instructions are not given, the plane will automatically fly in a circle with the island coordinates as the centre. Should strong side winds prevail during the flight the controller will sense that the direction of heading is incorrect and automatically insert compensation aimed at successful arrival at the desired coordinates. This is a very different system from the autopilot on the fishing boat. On the boat it is the heading direction which is controlled; on the Fl 11 it is the arrival position (coordinates) which is controlled. System types To summarise, systems can be divided into two types: [a) Open Loop Systems in which the input or command is inserted into the controller and we hope the correct result app13ars as the output. as in Fig, 1. That's all there is to it· you might call them "hope for th~ Speed regulator In a direct drive record turn- LIMIT SWITCH ON COLUMN WORKED BY RISING HOIST \ J_ __ , -------j r ___ I I I I HOIST I ==S=CA=F::::F/=LD=ING=L=·Ev=EL====:::::1 Fig.4: a limit switch can be used to stop the hoist automatically. Motor over-run after switch-off is the problem here. 12 best" systems. Such systems are simple, stable, inaccurate, not automatically error-correcting, and are often under human control. [b) Closed Loop Systems in which the input command is inserted into the controller, an output occurs, and something is fed back from the output to tell the controller how accurately the input command was obeyed. The controller is capable of correcting the output if it is not right, as in Fig.2. SILICON Cllll' This is a fantasy, with a theoretical message. A group of young electronics enthusiasts were standing on the footpath watching the construction of a multi-storey building. Being "of enquiring mind" they watched, fascinated, the electro-mechanical feedback control problem which unfolded before them. In Fig.3 we see a hoist used in a building under construction. Workmen wheel barrows of wet cement onto the hoist, then switch on a motor to lift the hoist and barrow of cement up to the level of the scaffolding. Another workman wheels the barrow off the hoist onto the scaffolding platform to the worksite. The difficulty is that if the man working the motor switch is not good at it, he will stop the motor with the hoist platform not quite level with the scaffolding, leaving a step up to the scaffolding. If you have ever tried to wheel a builder's barrow of wet cement up even a small step, you will be very enthusiastic a bout improving the whole system. An improvement was suggested to the electrician on the site. A switch was mounted on the hoist to stop the motor when it reached the right level, as is done in many lifts [see Fig.4). This was a failure as motors take time to stop after being switched off and some "over-run" was bound to occur, varying with different weight loads. Something better was needed. Somehow any over-run must be automatically corrected. Closed loop system As shown in Fig.5, a method was devised to generate a voltage, Fig.5: in this scheme, a potentiometer provides an output voltage that's proportional to the hoist's vertical position. This voltage is then fed to the control circuitry. r----- ,I I HOIST I I I [b) Error Voltage = [A - BJ = positive when the hoist is lower than it should be; and (c) Error Voltage = (A - B) = negative when the hoist is higher than it should be. Clearly, the feedback voltage B subtracts from the input voltage A, and tends to make the output smaller, so it is called negative SCAFFOLDING LEVEL I b====== d======== POTENTIOMETER - - REPRESENTS VERTICAL POSITNJN OF HOIST which we will call B, proportional to the hoist's actual vertical position. Our intrepid electrician was really being innovative here. Tests showed that a voltage B = 5.1234 volts was generated when the hoist was actually level with the scaffolding, more when the hoist was higher, less when the hoist was lower. And the voltage B = 0 was generated when the hoist was down on ground level. At any position, the voltage was a linear function of the hoist's vertical position. As this voltage represents information about the output, it is called the feedback. The controller was an amplifier with a gain of 10 and powerful enough to drive the 50V 30 amp DC hoist motor directly. The input A was switched to zero when the hoist was wanted down on ground level. Similarly, input A was switched to + 5.1234 volts when the hoist was required to go up to the scaffolding. Finally, a difference amplifier was added between the input and the controller; ie, an amplifier whose output E is equal to the difference between two input points A and B. Thus: Error E = (A - B) As shown in Fig. 6, the switched input A and the feedback voltage B (which indicates hoist position) are the two inputs to the difference amplifier. The difference (A - B) was called the error voltage because the difference (A - B) truly represents the error in the position of the hoist. We note that: (a) Error Voltage = (A - B) = zero when the hoist is in the correct position; feedback. Errors apparent Then someone noticed a funny thing: the hoist never reached quite high enough, always stopping a little lower than the scaffolding. Always the motor stopped when the feedback voltage B was about 4.8 volts, the input voltage A being of course 5.1234 volts. That is, it stopped when the Error Voltage was (5.1234 - 4.8) = 0.3234 volts. This being amplified by 10 meant that the motor came to a stop when the voltage supplied to it fell to 3.234 volts. This is not surprising after all (even though it would have been nice if the motor could continue to run until the voltage supplied came right down to zero). No-one could expect a motor to give enough torque with only 3.234 volts applied, so it stopped. One of the observers then made the obvious suggestion: "Why not raise the amplifier gain to 100 instead of 10?" To quell any fears of overvoltage being applied to the motor the electrician raised the amplifier gain to 100 but arranged it so that the amplifier output would always be limited and never exceed ± 50 volts [to protect the motor). +5.1234VOLTS REFERENCE DIFFERENCE AMPLIFIER ZERO «;) SWITCH VOLTU,_ ERROR VOLTAGE E = (A-8) .,. CONTROLLER AMPLIFIER ACTUATOR = OUTPUT = POWER AMPLIFIER .,__ _ HOIST POSITION AND MOTOR I = I TURN SWITCH UP TO +5.1234V WHEN HOIST REQUIRED TO GO UP TURN SWITCH DOWN TO ZERO VOLTS WHEN HOIST REQUIRED TO GO DOWN MECHANICAL ___ CONNECTION NEGATIVE FEEDBACK VOLTAGE IS A _ _ _ _ _ _F_uN...c_Tm_N_OF_H_OI_ST_V_ER_nc_A_LP_o,.s1T_1o_N 1 1 +6V I -------'--,-s POTENTIOMETER VFB VFB = OV AT BOTTOM = +5.1234V WHEN HOIST IS UP AT SCAFFOLD ZERO VOLTS Fig.6: control circuit for a motor-driven hoist. The difference amplifier compares a reference voltage (either + 5.1234V or OV) with the voltage from the potentiometer. This gives an error voltage which is amplified and used to drive the motor. J\l'HIL HW8 13 HOIST VERTICAL POSITION UNLOADED HOIST VERTICAL POSITION I VOLTAGE A UNDERSHOOT LOADED HOIST VERTICAL POSITION f= O TIME TIME SWITCHED FROM OV TO +5.1234V Fig.7: the hoist position as a function of time. If the hoist is unloaded, it will tend to oscillate about the desired stopping point. Now the hoist went up like a charm with a full barrow of cement in it. stopping much closer to correct position. This was because at the point where it used to stop, the error voltage of 0.3234 volts was being multiplied by 100 to 32.34 volts and of course the motor kept running up until the error in position was only about 1110th as much as before. One of the bystanders observed that the error in position appeared to be reduced by the same factor that the gain was increased. She guessed that perhaps the error in position of the hoist might be inversely proportional to the gain of the amplifier. and wondered, "Would the error be nearly zero if the gain were increased to 1000 or 1,000,000? Can the gain be increased indefinitely?" The answer to the silent question came when the builder sent the hoist up empty with no load at all. What happened gave everyone a fright! With no load at all the hoist went up quite quickly. The big gear wheel on the hoist winding drum got up to quite a speed and, of course, stored up considerable rotational momentum and rotational energy because of its moment of inertia. When the hoist got close to the scaffolding height the voltage applied to the motor reduced towards zero, but with no load the rotational stored energy in the gearwheel [and 14 SIUCON Cl/IP in the motor and winding drum too) just kept the hoist running. It shot right past the point where it should have stopped, eventually coming to rest 400mm too high. Of course, the feedback voltage up here was higher than 5.1234 volts, actually 5.32 volts. This made the error voltage E = (5.1234 - 5.32) = - 0.2 volts. This, when multiplied by 100 in the amplifier, produced - 20 volts [note that negative sign) at the motor, which thus reversed direction, sending the hoist plummeting downwards! It went right past the scaffolding position where E = zero, down at least 200mm too low before it stopped, where the amplified error voltage [now positive) measuring about + 15 volts sent the hoist up too high again! This went on for a few minutes until finally the hoist came to rest quite close to the correct height while the builders stood and watched with their mouths wide open. Clearly they had to know something about the dynamics of the system, whether mechanical, electrical or anything else! Someone drew a rough sketch of the vertical path of the hoist as a function of time, reproduced here as Fig.7. One bystander thought that this sketch looked just like the response of a second order differential equation when disturbed by a step function [ie, something just switched on). Someone said that the gain of the amplifier would have to be reduced and the error in the hoist position tolerated, but another observed that if the moment of inertia J of that big gearwheel could be reduced, they might not have to reduce the amplifier gain and could thus keep the error small. It then occurred to the onlookers, more or less simultaneously, that it ought to be possible to develop a theory to describe the antics of this hoist. Obviously, such a theory would be of enormous benefit to anyone who wanted to design elecronic amplifiers or machines, as then they could choose how much error, if any, whether it would overshoot the landing or not, and how stable the thing would be - and all this before it was ever built! It wasn't hard to see that such a theory would have a little mathematics in it, but that would serve to make it an elegant theory. Also it was pretty clear that this theory would include a few equations containing symbols representing things like Moment of Inertia (J), the Rotational Spring Constant of shafts [K) and something to describe any form of loss such as Bearing Friction or Brakes [B). Then of course all the electronic bods would want their C for capacitance in Farads, L for inductance in Henries, and G for conductance in Siemens [G Siemens = 1/R ohms). Naturally the variables would be volts [the "across" variable) and amps [the "through" variable). Someone quietly observed that all these constants J, K, B, C, L and G all represented quantities that were always positive, real and constant. So they would be nice things to have as coefficients of the equations. Remembering that graph of the overshooting and undershooting of the hoist we showed before as Fig.7, and the observation at the time that it just looked like the solution to a differential equation they had seen somewhere, they excontinued on page 96 HIFIREVIEW Arista ms 606 compact loudspeaker system By LEO SIMPSON This compact two-speaker system from Arista is unusual in that instead of being a bass reflex or sealed system, the enclosure is a labyrinth. Labyrinth enclosures have not been too common in the past because they are more complex to make than the more common enclosures. The point in their favour is that they reputedly have a very flat and well damped bass . response. Another unusual feature of this system is that the woofer has two voice coils, one for the midrange and one for the bass, so that when combined with the tweeter, the CDS 606 can be electrically described as a 3-way system. The woofer is a nominal 15cm unit with a carbon fibre reinforced cone and a neoprene rubber roll surround and quite a massive magnet system. The crossover network operates at 400Hz and 3.5kHz and gives a 12dB/octave slope to feed the tweeter (ie, the signal fed to the tweeter is rolled at 12dB/octave below 3.5kHz). The 25mm soft dome tweeter is also a little unusual, for a system in this price range, because it has a ferrofluid damped voice coil. The enclosure is quite complex really although the la bryrinth feature is relatively simple. For a start, the baffle of the enclosure is tilted back to provide time alignment (ie. to ensure that the woofer and tweeter voice coils are in the same vertical plane) and the corners are rounded which is usually done to reduce diffraction of the higher frequencies. It also makes the enclosure more attractive to some peoples' eyes. Unfortunately the effect is probably a little spoilt by the substantial sides of the removea ble grille cloth frame although that won't worry most people. The labyrinth is ported at the rear so the enclosure cannot be placed against a wall. It is most suited to floor placement and it does not take up much space. It measures 22 x 24cm at the base and stands 48cm high, quite a lot smaller than the photos might indicate. Impedance of the system is a nominal 8 ohms and this is in line with the impedance characteristic which falls to a minimum of 4.5 ohms which will cause no problems with modern amplifiers. Efficiency is a little on the low side though, at a stated 85dB/W/metre, and a 50W/ch amplifier is needed to drive it to good sound levels. Listening tests indicate that the frequency response is quite smooth over the range up to 20kHz although the tweeter is a little more prominent than the woofer. There's not a lot of bass below 90Hz either although the overall sound quality is quite well balanced. On music, they are at their best with popular instrumental and rock and most people will find them ideal for listening where space is at a premium. Nicely finished, they are good buying at just $399 a pair. For further information and the location of the nearest stockist, contact Arista Electronics Pty Ltd. Phone (02) 648 3488. It J\l'/lll, 1088 15 THE WAY I SEE IT By NEVILLE WILLIAMS Audio power ratings - right back to where we started from Having agreed some years ago that music power was a highly suspect rating, the world hifi industry settled on RMS watts as the true measure of amplifier power output. But since then, music power has gained totally new respectability and even been legitimised by the term "headroom"! I don't deny that there are supportable reasons for this apparent about-face but, in thinking them through, I was reminded of many other technical twists and turns that have confused the subject of audio power output ever since about 1930, when enthusiasts first began to take note of it as a parameter in its own right. Before then, audio output watts or, more fittingly, audio output milliwatts hardly rated a mention. Enthusiasts simply got to know, by experience or repute, that some valves were "louder" than others. The legendary 201-A detector/amplifier triode, for example, frequently used in the final stage of old-style battery sets, didn't even have an official power output rating. Figures were published for its derivatives, the 112-A (285mW max.) and the 71-A (790mW max.) but at a time when most receivers were powered by batteries or eliminators, the figures that really mattered were plate voltage and plate current. If either was unattainable or unaffordable, tough! For most enthusiasts, awareness of rated power output followed the release, in 1929, of the mains type 45 triode, the first substantial 16 SILICO N CHIP "receiver" type power valve. Under maximum supply conditions (330V) it offered a healthy 2 watts of output power in single-ended class-A, and up to 18 watts in pushpull class AB2 . Its dominance was shortlived however, because the 47 power pentode, released about eighteen months later, offered higher gain and 2.7W in single-ended class-A at the more manageable supply voltage of 270 - about twice the power available from the 45 at the same figure. Watts missing? But the 47 was not without its critics. Maybe it did have more gain but they didn't like its "tone" and it certainly didn't sound anything like twice as loud as the 45. The manufacturers were obviously having them on! But they weren't. Audio enthusiasts had yet to accept the sobering fact that a 2:1 (or any other) increment in audio power, or sound pressure level, is not subjectively apparent as such. Our ears spontaneously re-scale all such changes to an approximate logarithmic base - nature's way of enabling them to cope with a huge real-life range of sound pressure levels, from the merest whisper to the shattering roar of a not-somodern jet plane (modern ones are quieter). It was to quantify this natural logarithmic relationship that scientists devised the "bel" and its more practical derivative, the "decibel", abbreviated to dB. Taking the above 2:1 power ratio as an example, conversion to a decibel relationship involves taking the log (to the base 10) of 2, which turns out to be 0.3010; multiply this by 10 ·and call the result decibels say 3dB. And therein lies the answer to the fate of that supposedly missing watt: to the ear, with its logarithmic response, a 3dB change in level is perceptible but certainly not twice as loud. Watts twice as loud? If you're expecting a change in SPL (sound pressure level) sufficient to be described subjectively as " twice as loud", you need a decibel ratio of 10, or a 10-times boost in output power. To double the apparent loudness of that ancient 45 triode would call, not just for a 47 pentode but for a valve able to deliver 20W from a singleended stage or 180W from a pushpull pair - a rather tall order. If memory serves me correctly, no "receiver" type output valve has ever been marketed which could meet that requirement. Even today, to conservatively design a solidstate amplifier with an output of 20W single-ended or 180W in pushpull, you're still likely to end up with a parallel configuration! It's rather odd, when you think about it, that in terms of power output rating, most of the receivers and amplifiers that hifi enthusiasts have used during the past 50 years fall into a l0dB slot; from say, 10W for time-honoured push-pull 2A3s to 100W, covering virtually all other valve amplifiers and the vast majority of their solid-state counterparts. So be careful before you start boasting that your pet system can be twice as loud as the one next door. Unless you have 10 times the audio power and/or more sensitive loudspeakers, it can't! Watts and efficiency On the strength of that last reference, I should perhaps interpose the observation that in the context of loudness, many hifi enthusiasts are still unclear about the importance of loudspeaker sensitivity - the efficiency with which loudspeakers convert electrical drive power to sound. Loudspeaker sensitivity depends on design factors too numerous to catalog here but the intensity of the magnetic field surrounding the voice coil looms large as one of them. How sensitivity is measured is also beyond the scope of this article but it is expressed in decibels (referred to a sound pressure level of 12µbar at a distance of one metre) and curiously, the sensitivity range of domestic hifi loudspeakers, used over the past 50-odd years, also happens to be about 10dB wide - from around 85dB for comparatively insensitive systems to 95dB for models of reasonable efficiency. For a given level of audio drive (within overload limits), a 95dB loudspeaker system would be expected to sound twice as loud as one with a sensitivity of 85dB. On that basis, a venerable pushpull valve stereo amplifier, delivering 10 + 1OW RMS to a pair of those large and notably sensitive circa 95dB Wharfedale or Goodmans drivers of 25 years ago, would develop about the same SPL as a 100 + 100W solid-state amplifier feeding a pair of low efficiency (85dB) compact enclosures. These days, the "average" hifi FOUR POWER PENTODE valves from the late 20's and early 30's (from left to right]: type 33, 42, 45 and 2A3. Power outputs were in the region from 2-3 watts. enthusiast probably ends up with an in-between combination: around 40 to 60 watts of amplifier drive, a loudspeaker sensitivity of around 90dB and a marginal loudness advantage of about 2dB over the above extremes. In short, whether visualised in watts or decibels, audio drive power, on which we place so much emphasis, is only half the story. How efficiently we convert it is just as decisive! Watts available! But back to the 1930s: despite the levelling effect of ears and decibels, valve and receiver manufacturers of the period kept right on doggedly chasing small power increments, which would hopefully catch the buyer's eye, even if their ears were unmoved. For engineers at least, it was visually stimulating to see a larger pattern on the CRO screen and a higher reading on the output meter, especially in the knowledge that, to calculate the power resultant in watts, the formula required the voltage reading to be squared: P = E 2 /R That was fine but at an aural level, instead of squaring something, listeners were lumbered with logarithms, often ending up with a thoroughly unexciting 2 or 3dB an exercise that, if nothing else, served to separate technically in- dined pessimists from their opposite number. "It's not worth doing this or that", they would say, "because the difference won't be noticeable". To which the optimists would reply: "Rubbish! Put enough 2dBs end to end and, somewhere along the line, you'll end up with a difference worth having!" In a roundabout way, I guess, they were both right! Watts impedance? But valve or solid-state, with or without an output transformer, audio amplifiers normally end up feeding into a loudspeaker load one that is generally more reactive than resistive, having an impedance that can vary widely with frequency and which may approximate its rated value across only a limited portion of the spectrum. That's common knowledge, but I wonder how many realise the extent to which it compromises our oh-so-tidy thinking, based on those convenient but fictional resistive loads used for most power measurements . Watts or volts? By definition, any amplifier these days using adequate negative feedback has a substantially "constant voltage" output characteristic with loads of not less than a specified value. As a corollary, such an APRIL 1988 17 amplifier will also have a low output impedance and a high damping factor. . As such, it should have the potential to combine well with any ordinary hifi loudspeaker system, for which the normal design objective has been to achieve an adequate SPL in the listening room, when fed from a compatible "constant voltage" amplifier. Audio power, as such, does not appear in the above statement; nor can it in any precise way because, while the audio voltage at the amplifier/loudspeaker interface can be monitored and measured, the impedance and power factor of the load itself is subject to wide instantaneous variations with frequency. But, with rare exceptions (eg, SILICON CHIP, Feb. 1988, p.40) we simply pretend that loudspeakers are high-wattage resistors of, typically, 4 or 8 ohms. On that basis: (a) We quote their normal and maximum drive levels in terms of fictitious watts rather than the actual volts with which they are normally Did you fed and on which their frequency rating is based. (b) We likewise measure and rate amplifiers on their ability to deliver power into resistive loads which, in fact, they rarely encounter. Maybe I'm being over-pedantic. Maybe it's a bit like Santa Claus: easier to go along with the fiction than to complicate kids' lives by denying it! Admittedly, there are a few loudspeaker systems around in which the reactive components have been substantially balanced out but I wouldn't advise holding your breath until the technology becomes the rule rather than the exception. Watts - the genuine variety This brings us back to where this article began - the about-face in relation to amplifier power ratings. In its post-war resurgence, the hifi industry adopted the practice of quoting the audio power delivered to a load resistor across the output-to-voice-coil terminals at the onset of overload. The test was done under con- • llllSS tinuous tone conditions, using a lkHz sine wave and such other frequencies that the designer might choose. The figure obtained was commonly ref erred to as the RMS power output - a term that was challenged on principle by some who maintained that there was no such quantity as RMS power. It has persisted, however, on the grounds that it refers to power derived from a measurement of RMS voltage. Continuous tone testing was recognised as a conserve tive method but justified because it indicated the ability of an amplifier to handle sustained passages of loud music as, for example, the heavy bass pedal notes of a pipe organ. It was a comfortable enough rating for generously designed amplifiers but an embarrassing one for " budget" models in which sustained loud signals of any kind caused a reduction in the internal supply voltage and, with it, a reduction in the measured power output. Watts - music and peak In consequence, some manufacturers ignored the RMS convention these issues? Issue Highlights January 1 988: 4-Bay Bowtie UHF Antenna; Dual Tracking Power Supply; Custom Phone Ringer; Subcarrier Adaptor for FM Tuners . Please send me a back issue for □ November 1987 □ December 1987 □ February 1 988 □ March □ January 1988 t 988 Enclosed is my cheque or money order for $ ... ..... or please debit my □ Bankcard □ Visa Name .. .. ..... ... ... ... .. ....... .... .... ..... .... .......... .... .. ... ... ...... .... ... ...... ..... .. Address .. ... ... .. .. ..... ...... ........ ... ........ ... ..... ... .. .. ............... .. ...... ....... . Suburb/town ...... .... ... ... .. .. ..... ..... .. ... ... ... ....... .... Postcode .. .... ... .... .. . Card No .. ..... .. ... .. .. ... .. ..... .. .. .. .. ... ........................... .. ..... .. .. .... ... ... .. . Signature .... ... .... ........ ....... ... ....... ..... Card expiry date .. ... .. / .... ... / ... ... . February 1 988: 200 Watt Stereo Power Amplifier ; Deluxe Car Burglar Alarm; End of File Indicator for Modems; Simple Door Minder; Low Ohms Adapter for Multimeters. March 1 988: Remote Switch for Car Alarms ; Telephone Line Grabber; Low Cost Function Generator; Endless-Loop Tape Player. Price: $5.00 each (incl. p&p). F ill out the coupon at left (or a photostat copy) and send it to: SILICON CHIP , PO Bo x 139, Collaroy Beach 2097. ~---------------------------------------18 SIUC() N CIIII' and began rating their amplifiers in "music power", signifying the output available at the onset of distortion during short musical phrases. It could typically be from 10-30% above the RMS rating, so that a humble 10 + 10W amplifier might well be rated at 13 + 13W music power. To create a still better impression, the two figures could be added together to yield "26W total music power" . But then someone else realised that the instantaneous power at the peak of a sine wave was twice that . of the sine-wave itself, permitting the aforesaid humble 10 + 10W amplifier to be re-rated yet again to 26 + 26W peak music power or "a massive 52 watts of total peak music power". Such tactics gave the hifi industry a thoroughly bad name and consumer pressure in the US eventually led the Federal Trade Commission to rule in 1974 that amplifiers must be rated in terms of continuous power outout. Further, in testing the power output of an amplifier. it would be subject to an hour's preconditioning at 33% of its rated power. This caused great consternation among amplifier manufacturers because it meant that amplifiers had to be designed more conservatively, particularly as far as their power supplies and heatsinks were concerned. Subsequently, music power was re-defined and recognised in the 1978 IHF (Institute of High Fidelity) standards as a supplementary rating, together with a new term, headroom, which referred to the decibel ratio of music power to continuous power. But music power was still regarded by many as a Clayton's output: watts you had when you really didn't! Watts - transient peaks? But, as I indicated right at the outset, the recording scene has changed drastically during the past decade, as also have our expectations of amplifier performance. Around the mid-70s, audio engineers became increasingly aware that, while their analog tape decks were producing ostensibly clean master recordings, they were subtly crushing the high amplitude transients - a problem of dynamic range for which there appeared to be no ready answer. Then quite suddenly, through the efforts of resourceful professional recordists, hifi enthusiasts were confronted with a sequence of new "ear popping" audiophile discs, some direct cut, others dubbed from digital master tapes. It so happened, at that opportune time, that I acquired a then-new Technics SU-V 4 70 + 70W integrated amplifier, fitted with fluorescent peak-hold level indicators calibrated to 100 + 100W. For the first time, in a home listening situation, I was exposed to recorded transients that not only gave pianos, acoustic guitars and other percussion instruments a startling sonic presence but which, from no more than ample room volume, flicked the level meters to 50 watts or more - well above the reading for a sustained, subjectively loud, organ or orchestral fortissimo. Clearly, a new era had dawned, which was soon to be perpetuated by compact discs. Taken at face value, the above observation suggests that a hifi enthusiast who likes to listen at a generous domestic level, using typical loudspeakers (1 W, lm, 90dB), now needs several hundred watts per channel to be reasonably sure of coping, not so much nowadays with fortissimo passages, but with the high amplitude transients that characterise some modern recordings. Such amplifiers are very expensive and can easily run into many thousands of dollars, particularly if they fully conform to the US FTC standards. There has to be another way, and there is. In the last few years a number of manufacturers have looked at the concept of headroom. Why not design an amplifier with far more headroom than previous designs offered? Instead of having a headroom figure of say, ZdB, which is fairly typical of current designs (such as the Studio 200 described in the February 1988 issue of SILCON CHIP), why not go for a headroom figure of 6dB? 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CARJAYCAR A corrpact high quality tuner that operates from 526-814MHz (corresponding to CAR JAYCAR CAR JAYCAR channels 2Q thru 63). This tuner is designed for Australian standard reception This unit Is designed for midrange and tw88ter CAR JAYCAR (AS1053 1973), and is offered at a very low price. CARJAYCAR controls on multiway speaker systems. It Is You can grab one now for the silly price of $29.951 This price Includes circuit :ARJAYCAR suitable for systems up to 80 watts power diagrams and connection drawing. You can have a photocopy of the complete :AR JAYCAR handling capacity. It presents a constant 8 ohm manual for $4 but a lot of the info is In Japanese! Another Jaycar exclusive purchase. Allows :ARJAYCAR impedance to the load, and so does not disturb This is a very cheap way to convert a VHF only TV to UHFI (Some skill may be you to connect two phones to the one :AR JAYCAR the crossover points. Unit is fully sealed, :AR JAYCAR required). socket. 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They need a good clean up and JAYCAR JAY certainly isni. They are Japanese made, some TLC. JAYCAR JAY with a large magnet. It even has a foam roll We cannot however give any warranty at all on these. We JAYCAR JAY surround . These were used in colour TV's, JAYCAR JAY suggest that if you need say 4 batteries, you purchase 6 or 8 We have available a small quantity of the very old style brown so the quality is excellent. Sanyo brand 8 JAYCAR JAY you may even get the majority going. It's still the cheapest AA bakelite 4 pin round telephone plugs and sockets. These were used JAYCAR JAY ohm 5 wan. Limited quantity. These would NICad deal you'l;I see In a long time. JAYCAR JAY on the very old black rotary dial phones. probably cost $30 as a spare part II NORMALLY $4.25 JAYCAR JAY Due to the limited quantity they are only available from the mall order Cat. AS-30 15 JAYCAR JAY Cat. SB-2453 department. JAYCA R JAY JAYCAR JAY JAYCAR JAY 10+ $4.50 ea Limited quantity. No warranty - No return JAYCAR JAY JAYCAR JAY JAYCARJAY JAYCAR JAY JAYCAR JAY JAYCAR JAY Now available In 2 sizes In 5 metre lengths. High quality US made wire JAYCAR JAY wrap wire in 24 and 28 guage. Both green In colour. JAYCAR JAY Cat. WW-4350 24 guage $2.95 5 metres length JAYCAR JAY Another new addition to our range of Australian made Cat. WW-4365 28 guage $2.95 5 metres length JAYCAR JA'Y Magnavox woofers . Suitable as a woofer or a midrange. JAYCAR JAY Power Handling 40 watts RMS JAYCAR JAY Freq. Response 50 - 6500Hz JAYCAR JAY Resonant Freq. 55Hz JAYCAR JAY JAYCAR JAY Voice Coil Dia. 25mm JAYCAR JAY Sensitivity 93dB JAYCAR JAY Will give excellent results as a midrange in the frequency JAYCAR JAY range 500Hz - 5kHz. Needs to be mounted In a sealed ;\, JAYCAR JAY . , .., enclosure of 2-4 litres. Will handle 60 watts RMS as a JAYCAR JAY SERVICEMEN TAKE NOTE! JAYCAR JAY midrange. Check out the special below. You will have to be quick! JAYCAR JAY JAYCAR JAY 2SD870 JAYCAR JAY Cat.CW-2107 Toshiba brand TO-3 horizontal deflection transistor. Silicon NPN, 5A JAYCAR JAY IC. 600 Vee, 1500Vcb, 50W diss. JAYCAR JAY JAYCAR JAY Quantity limited JAYCAR JAY Cat. ZT-2520 ~ JAYCAR JAY JAYCAR JAY JAYCAR JAY JAYCAR JAY ~00~ We have a small quantity of tips to suit the Weller JAYCA R JAY Sanyo brand T0 -3. 12A IC, 400Vce. NPN silicon. W60D and W100D 240 volt temperature controlled JAYCAR JA.Y Our usual desolderwick is sold in a plastic spool MAIL ORDERS ONLY soldering irons. JAYCAR JAY and contains 5 feet for $2.50. That 's approxiCat. ZT-2515 Cat. No. Oty JAYCAR JAY Weller No. mately $1.50 per metre. JAYCAR JAY Avail El cheapo braid is 2mm wide and will take solder JAYCAR JAY CT5BB8 2.4mm 427° TS-1390 11 off a PCB reasonably well although the braid gets JAYCAR JAY 2SC1507/2SC1569/2SC2336 CT5CC8 3.2mm 427° TS-1391 54 JAYCAR JAY a bit hot because there is no plastic spool to hold. CT5DD8 5mm 427° TS -1392 103 Most NEC brand TO-220 (mod). HF power transistor. Can be used as JA YCAR JAY You could easily put some in your old spool. CT5EEB 6.4mm 427° TS-1393 41 video amplifier or low power HF power amp . 300Vce, NPN , 150mA JAYCAR JAY Supplied in a 5 metre leng1h for $2.50. That's soe JAYCA R JAY These would normally cost about $11 each. IC. FTlOOMHz. 12W diss. metre - or 113rd the price of normal desolderwick. JAYCA R JAY Because of ihe small quantities. you 'd better be Cat. ZT-2510 Cat. NS-3025 5 metre pack JAYCA R JAY quick. Please note: braid is not loaded with flux and will JAYCA R JAY JAYCAR JAY not work quite as well as normal desolder braid. JAYCA R JAY JAYCA R JAY JAYC AR JAY JAYCA R JAY JAYCA R JAY JAYCAR JAY JAYCAR JAY JAYCAR JAY JAYCAR JAY JAYCARJAYCAR JAYCA R JAYCAR JAYCARJ AYCARJAYCARJ AYCA RJ AYC ARJ AYCARJ AYC A RJ AYCARJ AYC AR JAYCARJ AYCAR JAYCAR JAY CARJ AYCA RJ AYCARJ AY CAR JAYCAR JAY JAY JAYCAR JAYCAR JAYC AR.J AYCAH JAYCAR JAYCAR JAYCAR JAYC AR JAY CA R JAYC AR JAYC AR JAY CAR JAYCA fi JAYC A R JAYCAR JAY CAR JAYCAR JAYCAR JAY CAR JAYCAR JAY CAR JAY ; A R JAYCA R JAYCAR JA YC Ai-1 JAY CA R JAY CAR JAYCAR JAYCAR JAYC AR JAY CAR JA.YC AR JAYCA R JAY CAR JAYCA R JAYC A R JAYC AR JAYCA R JAYC AR JAYCAR JA YC AR JAYCAR JAYCAR JAY ; AR DIGITAL WATCH KIT Hi Quality Speakers at Silly Prices $5.95 $3.95 ea $4.25 ea 10+ $3.95 ea 10+ $3.65 ea 100+ $3.50 ea $3.95 ea 10+ $3.65 ea 100+ $3.25 ea $5.95 ea 10+ $5.50 ea $4.95 ea 10+ $4.50 ea $8.95 ea 10+ $8.00 ea $13.95 ea 10+ $12.95 ea ONLY $13.95 box of 10 OLD STYLE (Antique) TELEPHONE PLUGS AND SOCKETS AA NiCads - $1 !!!!!! 6" Plug Wall Mount Socket $1.00 each $4.95 ea $5.00 each $5.00 each WIRE WRAP WIRE MAGNAVOX 40 WATT WOOFER/MIDRANGE )~;. ~ µ~ ::SPECIAL INTRODUCTORY PRICE x 2" SPEAKER!!!! ,..,,. Sensational Semiconductor Bargains ,' $19.95 ea ~ WELLER TIP SALE $2.50 ONLY $2.50 . . o DESOLDERING BRAID $2.00 ONLY $4.95 each $1 .50 AND NEW PRODUCTS I AY C AP 10:vc o, g 11\YCOR 1 ov r og 1 0, v r o □ lO Y C /\0 IAY C OA I OYC A A I AYC A R IAYC AR I AYCAR 10:YC AR I AYC A R IAYC A B IAYC A R I AV C A R IAYC AR I AYC A R I AY C A A .IAY C AR IAYC AR IAY ' AR • . .. . . . . •. . - · · · · - · · · - · · · · - · · · - · · · ·-· · · - · · · · -· · · - · ···-·· · ...., ·" · -··· ...., , .. ,..,,,, ..... ,... ,, ... r, ,,.__, r-,. , 1 ... ,... , vn 11,J M I\JMnVM I VMn JM T VMMJI-\ T VI ;AR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYC1 ; AR JAYC AR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYC AR JAYCAR JAYC AR JAYCAR JAYC1 ;AR JAYCAR ; AR JAYCAR ; AR JAYCAR ; AR JAYCAR ;AR JAYCAR ; AR JAY CAR A very well known Australian manufacturer of modems came to us with a problem. They had a smallish number of their No.1 selling intelligent modems left from their final ; AR JAY CAR production run. (The product was being discontinued because their upgraded 1988 model intelligent modem is fitted in a smaller more attractive case. They were anxious to clear ; AR JAYCAR ;AR JAYCAR the old stock fa make way for the new. To be frank, however, there is a snag even though it is in realny a very small snag. What is n? ; AR JAYCAR HAYES COMPATIBILITY. "Hayes" command protocol is used by the intelligent modems to communicate with each other. The problem is that this intelligent modem only uses a ;AR JAYC AR subset 61 the Hayes command protocol. (This can be likened to IBM 'Clone' type computers. Most are not 100% IBM compatible. They work well anyway). Mind you, the above is ; AR JAYCAR only a problem nyou were say, a bank or large corporation trying to use this modem to receive information at high speed from their intelligent modems! ; AR JAYCAR BUT if you use n as an ORIG INATE modem, i.e. as a house use/hobbyist etc., it is pertect WE GUARANTEE THAT. \AR JAYCAR This is a wondertul opportunity to buy a high speed (1200 baud FULL DUPLEX) modem with auto diaVauto answer FOR THE PRICE OF A LOW SPEED DUMB MODEM I :AR JAYCAR : AR JAYCAR REMEMBER the only drawback is that n will not ALWAYS work with "smart' software but will always work in the terminalNiatel mode. ; AR JAYCAR We have purchased this product FAR BELOW manufacturers factory cost. Massive savings are being passed on. This price is 112 the price shown in our 1987 catalogue. A ;AR JAYCAR condition of purchase was that we did not reveal the manufacturers name, but you can always make an Average guess I ;AR JAY CAR SPECIFICATIONS: • Speeds 300 baud full duplex, 1200175 limited full duplex 1200 baud full duplex (option) ;AR JAYCAR '• Data standards CCITT V21, CCITT V23, Bell 103, CCITT V22 (option) Bell 212 (option)• Interface CCITT ;AR JAYCAR ; AR JAYCAR V24 (RS232) • Data format Asynchronous• Diagnostic Analogue and dig ital loopback • Filtering dignal, ;AR JAYCAR no adjustment crystal locked• Power 240V AC• Modulation Frequency shift keying phase shift keying ; AR JAYCAR (with V22 option)• V21/V22/V23 (1 200/1200 option fitted) ;AR JAYC AR Cat XC-4834 ;AR JAYC AR ; AR JAYCAR ; AR JAYCAR ' AR JAYCAR ;AR JAYCAR 'AR JAYCAR ;AR JAYCAR ; AR JAY CAR ;AR JAYCAR ; AR JAYCAR '.AR JAYCAR '.AR JAYCAR ;AR JAYCAR '.AR JAYCAR '.AR JAYCAR You will never see the fabulous AEM 6103 3 way Vffa speaker kit cheaper. These kns are superceded, so we '.AR JAYCAR '.AR JAYCAR must move all our current stocks. ;AR JAYCAR The new kits have modifications to the crossover and cabinets, the speakers remain the same. ; AR JAYCAR These kns are normally $1199 wnh cabinets. A lucky few customers can purchase a pair for only $999 ' AR JAYCAR SAVING A MASSIVE $200. '.AR JAYCAR There may also be some demo speakers available for personal shoppers. We suggest you ring our stores to ;AR JAYCAR ;AR JAYCAR check out the situation. These include 60160, AEM 6102 and AEM 6103. '.AR JAYCAR '. AR JAYCAR '.AR JAYCAR '.AR JAY CAR '.AR JAYCAR :AR JAYCAR 'AR JAYCAR 1 :AR JAYCAR ;AR JAYCAR ;AR JAYCAR ;AR JAYCAR ;AR JAYCAR ;AR JAYCAR ;A R JA':'CAR ;AR ·JAYCAR :AR JAYCAR :AR JAYCAR :AR JAYCAR :A R JAYCAR :AR JAYCAR :AR JAYCAR :AR JAYCAR ;AR JAYCAR :AR JAYCAR :AR JAYCAR eully built and tested with separate bass, treble, balance and volume controls. This :AR JAYCAR superb amp has less than 0.1 % distortion. There are inputs for microphone, phone :AR JAYCAR • Crossover frequency 500, 3500Hz and auxil iary (line) and all power supply components are on board. Just connect a :AR JAYCAR • 12dB attenuation transformer, speakers and a signal - and away you gol Requires 36-38VAC x 2. :AR JAYCAR Ref: EA January 1988 • 200 watts RMS :AR JAYCAR Size: 186 x 145 x 40(H)mm This is an easy to build temeprature probe • 8 ohms :AR JAYC AR which adapts a multimeter or electronic Cat AA-0300 -AR JAYCAR Cat. CX-2621 voltmeter into a general purpose thermometer. Transformer to suit • AR JAYCAR Prototype was tested from -20• to 120•c at AR JAYCAR 1% accuracy. AR JAYCAR ~;t2~sMci2010 AR JAYCAR Al uminium tube not supplied . AR JAY CAR Cat KA-1696 AR JAYCAR AR JAYCAR AR JAY CAR AR JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR off on " AR JAYCAR AR JAYCAR temperature AR JAYCAR AR JAYCAR probe AR JAYCAR AR JAYCAR 10mV/ll AR JAY CAR Et~1r<ii11lC-$ Au~t,:.l,a. AR JAYCAR AR JAYCAR I\R JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR I\R JAYCAR I\R JAYCAR I\R JAYCAR Ref: EA October 1987 I\R JAYCAR It will provide 8 different patterns and colour bars, I\R JAYCAR red screen, whne screen, black screen, crossI\R JAYCAR hatch, vertical lines, horizonial lines and dot I\R JAYCI\R I\R JAYCAR pattern. Synchronisation and blanking are to I\R JAY CAR 1 IRCC (International Radio -Consultative \ R JAYC AR i Committee) standards. \ R JAYCAR I Unn requ ires 12V AC<at> 500mA. \ R JAYCAR , Cat KA-1691 \ R JAYC AR \R JI\YCAR \R JAYC AR \ R JAYCI\R INTELLIGENT MODEM PRICE SLASHED!! SAVE OVER 50% WAS $699 NOW ONLY $349 ,,------ --------------- 1AEM 6103 VIFA SPEAKER KIT - - - -:- ;--\ I I I I I I I RUNOUT SALE I I I I I : VIFA/ AEM 6103 SPEAKERS, CROSSOVERS AND CABINETS I I I I ~!~~AvE_$2oo_________ ;fflll _ Low Cost Temperature Probe for Multimeters 30 + 30 Watt Stereo Amp ..J 200WATT 3WAY CROSSOVER INCLUDING PREAMPLIFIER $69 95 ~ri ·t.ttt, ' ,. • • "i••·•, , $69.50 $19.95 TV Colour Bar Pattern Generator $169 \ A JAYCA~ • .~-::::::::=:--· ·.....,,...... ····- -····---·-···-··· \ R ~~~g~R JAYCAR JI\YCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCI\R JAYCARJAYCAR JAYCAR JAYCAR JAYCAR o..-rwZl'l,ITTt-;\R JAn.AR JA\' <.:AR JAYCJ\R J J\V CA'!iJilYCARJAYCAR I JAYCARJAYCARJAYCAR JAYCAR JAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCAR JAYCAR I A JAYCAR JAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCAR JAYCAR \ ~ IAY/". AR .IAY/".AR .IAY<:AR .JAY<:AR JAY CAR JAYCAB..JAY.CAR.JAYCAR.JAYCARJA't'.CAB..JAYCAB...JA'lCAB...JAY.CA!LlAYCAR IAYCAR IAYC AA..mJLJAYCAR.IJu'.CAlL IAYCAR IAYCAR JAYC1 JAYC, JAYC, IAYC., JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARjAYCARjAYCARjAYCARjAYCARjAYCARjAYCAR j AYCARj AYCARj AYCAR JAYCARJAY:AR JAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCAR JAYC AR JAYCARJ AYCAR JAYCARJAY~AR JAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJ AYCAR JAYCAR JAYCARJ AY~ AR JAYC AR JA) JAYCAR JA) JAYC AR JA) JAYC AR JA) JAYCAR JA) JAYCAR JA) JAYC AR JA) JAYCAR JA\ R e f : AEM M a rch 1988 Ref: AEM April 1988 JAYC AR JA) JAYCAR JA\ Wi ll fully charge then trickle charge - or trickle charge only. Low powe r FM transmitter that picks up sounds and JAYCAR JA) Will charge up to 10 cells at once. Incorporates own plug pack box . transmits on FM . Cheap version of baby minder or JAYCAR JA\ JAYC AR JA\ Cat. KM-3067 pool m inder, etc . JAYCAR JA\ Cat. KM-3O68 • JAYCAR JA\ JAYCAR JA\ Ill,,,_ JAYCAR JA\ JAYC AR JA\ JAYC AR JA\ JAYC AR JA\ JAYCAR JA\ JAYC AR JA\ JAYCAR JA\ JAYC AR JA\ Ref : ETI April 1988 JAYC AR JA\ Monitor your baby' s room for crying . JAYCAR JA\ JAYC AR JA) Will trigger a light or buzzer in Ref: EAApril 1988 JAYC AR JA\ another room . Kit includes box, JAYC AR JA\ Amplifier offers power output o f 5 JAYC AR JA\ PCB, and all components except watts, signal tracer has high in put JAYC AR JA) 12V AC plugpack and dynamic mic. JAYC AR JA) impedance an'd a wide range of JAYC AR JA) Mic is currently on special for $4 .95 JAYC AR JA) input sensitivities. JAYCAR JA) (Cat. AM-4O95) Complete kit including box, JAYC AR JA) Cat. KE -4732 JAYCAR JA) speaker, PCB and a ll com p o nents . JAYC AR JA) P lug pack not s u pplied. JAYCAR JA) JAYCAR JA) Cat. KA-1699 JAYCAR JA) JAYC AR JA) JAYCAR JA) JAYCAR JA) JAYCAR JA) JAYCAR JA) JAYCAfi JA) JAYC AR JA) JAYCAR JA) JAYCAR JA\ JAYCAR JA\ Ref: Silicon Chip April 1988 JAYCAR JA\ JAYCAR JA\ Includes all the features of The Railmaster plus walkaround JAYC AR JA) JAYCAR JA) throttle . All components supplied less box and relay . JAYC AR JA\ Cat. KC-5O28 JAYCAR JA) JAYCAR JA\ JAYC AR JA) JAYCAR JA\ JAYCAR.JA) JAYC AR JA\ JAYCAR JA\ JAYCAR JA\ JAYC AR JA\ JAYC AR JA\ JAYCAR JA\ Ref : Silicon Chip April 1988 JAYCAR JA\ Ref : Silicon Chip April 1988 Kit includes PCB, plastic case , meter and scale , fro nt JAYCAR JA\ Kit includes PCB, box , all components and hardware . Requires 12V JAYC AR JA\ panel and all components . Probe is extra. JAYC AR JA) AC plug pack Cat. MP-3O2O $13 .95 JAYCAR JA) Cat. KC-5O27 Cat. KC - 5O29 JAYC AR JA) JAYC ARJ A\ JAYC AR JA) JAYCAR JA\ JAYCAR JA\ pH probe and solutions to suit Cat. QP-223O $79.95 JAYCAR JA) JAYCAR JA) JAYCAR JA) JAYCARJA) JAYCARJ AY JAYCARJAY JAYCAR JA\ JAYCARJA) JAYCARJAY JAYCARJAY JAYCARJAY JAYCARJA~ JAYCARJAY JAYC ARJAY JAYCARJ AY JAYC ARJAY JAYCARJ AY JAYC ARJAY JAY CAR JAY JAY CAR JAY JAYCAR JAY ' JAYCARJAY {%////////////////////////////////////////////~/////////////////7JJ'7>1/' /ll'//////////////////// / /////////////////// //////~//////////////////////1/~! ~g: ~ j ! ~ ""NiCad CHARGER r FM MINDER BUG $11 95 $24.95 BABYMINDER BENCH AMP/ SIGNAL TRACER $34.95 $39.95 RAIN CONTROLLER 0 $89.00 CD HEADPHONE AMPLIFIER pH METER ,$24.95 $49.95 "" ¼"1 ~~ ?, ~ 1/, ~ ~ /:_ 1 ~~,;, ~,% • •· 1/,SYDNEV • CITY 11 7YorkSt (02)2671 614- ~ HEAD OFF ICE ~ CAR LINGFOR D Mon-Fri 8.30 - 5 30 Thurs 8 30 pm - Sat 9 - 12 Cnr. Carl,ngford & Pennant Hills Rd (02) 872 4444 Mon-Fri 9 - 5 30 Thurs 8 30 pm - Sat 9 - 2pm ~ (02) 7 47 2022 ~ YCAR JA\ Te lex72293 ~ : ~g~j! ~ ~ YCARJ A) ~ YCARJA) '% ) I ~CONCORD 1/., _____...,._.,;;.i__, ,/2HURSTVILLE 11 5Parramatta Rd(02)74 5 3077Mon-Fri830-530-Sal8 30- 12 121Forest Rd(02)5707000- ?,:AYC ARJAY ~ 115 Parramatta Road ?,:AYC AR j !~ ~ Concord 213 7 ~~g~ JA) ~ ~ ~ ~ FACSIMILE (02) 744 0767 MAIL ORDERS ~~g~j!~ Mon -Fri 9-530Th urs830pm - Sat9-12 1ssPac~1cHwy cnrBellevue Ave(02)4394799 ~ P .0 Box 185 ?,:AYC ARJ A\ '-j MoMri9-530Sat9 - 4pm Concord 213 7 ?,;AYC ARj! ~ (MasterCard ' 144LoganRd(07)3930777~ HOTLINE ~ YCARJ A\ ~ ' · M F 9 5 30 Th 8 30 S 9 12 1//, i jA YC AR ,.'::~=:.:'.'..-.:~a:_ on- " · urs · at · ~ (02) 7471888 ~ AYCARJ A\ Shoo2,45 A'BeckettStC1ty(03)6632030 FOR ORDERS ONLY ~ AYC AR j ! ~ ~ ~ Mon-Fri9 - 530F ri 830 - Sal 9-12 ~ TOLLFREE ~ ~g! ~JA) VISA 887-889Springvale Road Mulgrave(03)5471022 (008)02 2 888 ~ YC AR JA) r, r Cnr Oandenong RoadMon -F ri 9 - 530 Fri 830 - Sat 9-1 2 _.:¼ ~ AYCAR JA) ~;;,;:~:,;.;-X,;){;:{0 ,1 /,/$~ ///////////////o MAIL ORDER VIA YOUR PHONE '////////////~//////////,(//////,1'////~AYCAR JAYCAfl'JAYCAH J YC AH JAYCAH JAYvAH J,' '"LAH JAYCAH JAYCAH JAYCAH . JAYCAH JAYCAH JAYCAH JAYCAH JAYCAH JAYCAR JAY : JAYCAR JAYl? A~ J~Xl?~~ J~X5'. A~ ,JAY f: A~ .JAX(~A~ J~X5'.~~ ~~X£~~ ~~X£~~ ~~X£~~ ~~X£~~ ~~X£~~ ~~X£~~ ~~X£~~ ~~X£".'~ ~".'X£ ".'~ ~~X£~ ~ ~".'X£ ".' ~ ~".'X5'.~~ JAX5'.~~ J~X5'.A~ JAX:~ ~ ½111• .'. , .---,, -·., ½ ½ ~--■■I - ½ ½ POST & PACKING 1/, GORE HILL $5 $999 $ 200 1/, $10 $2499 $375 ?,BURANDA OLD $25 $49 99 $ 4 50 1/, . $50 $9999 $ 650 1/, OVER$ 100 $10 001/,MELBOURNE-CITY ROAD FREIGHT ~ /l ~IYWl',ERE ?, SPRINGVALE VIC IN AU Sl f< AL,A $ 1350_, ½ ~))2 . ~ ~ ~ ~ df~ YLAHJM TVMnJMTvMnJM TVMnJMTV~MJATVAMJA TVAMJATVAMJATVAHJATVAHJATLAMJAYLAHJAYLAHJAY~AHJAY~AHJAY~AHJAY~AHJAYCAHJAYCARJAYC A RJAYCAR JAYCARJAYCJ YCARJAYCARJ AYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJAYC, YCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJ AY CARJAYCARJAYCARJAYCARJ AY CA RJAYCAR JAYCARJAYC1 YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCARJAYCAR YCAR JAYCAR YCAR JAYCAR Ref: Silicon Chip Nov. '87 YCARJAYCAR YCAR JAYCAR Build one into each phone so that Ref: SIiicon Chip YCAR JAYCAR a LED will then flash on every February 1988 YCAR JAYCAR extension to Indicate whenever This simple project YCAR JAYCAR the line Is In use. can be easily fitted YCAR JAYCAR Cat. KC-5011 YCAR JAYCAR in most modems Ref: SIiicon Chip December 1987 YCARJAYCAR and sounds a buzzer YCAR JAYCAR at the end of file YCARJAYCAR transmission,. YCAR JAYCAR Cat. KC-5018 Cat. KC-5024 YCAR JAYCAR YCAR ·JAYCAR YCAR JAYCAR RDE:115 thermistor to suit YCAR JAYCAR Cat. RN-3415 $8.95 each YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR YCAR JAYCAR Cat, KC-5019 RDE245A termlstor to suit YCAR JAYCAR Cat. RN-3418$10.95ea YCAR JAYCAR Ref: Silicon Chip Jan '88 YCAR JAYCAR This simple ad.i.ptor circuit fits in your FM tuner YCAR JAYCAR and lets you t.i.p into hidden FM transmissions . YCAR JAYCAR YCAR JAYCAR Cat. KC-5014 YCAR JAYCAR Ref: Silicon Chip November/December 1987 YCAR JAYCAR This superb 1GHz Diglt.i.l Frequency Meter will outpertorm any other instrument in Its (CAR JAYCAR price range. YCAR JAYCAR Kit Is complete with laser cut silk screen front panel, anodised punched rear panel (CARJAYCAR (CAR JAYCAR and all parts. (CARJAYCAR Cat. KC-5013 fCAR JAYCAR (CAR JAYCAR (CAR JAYCAR ( CAR JAYCAR ( CAR JAYCAR (CAR JAYCAR ( CAR JAYCAR ( CAR JAYCAR (CAR JAYCAR ! CAR JAYCAR (CAR JAYCAR ( CAR JAYCAR ' CAR JAYCAR ' CAR JAYCAR ' CAR JAYCAR Ref: Silicon Chip January 1988 ' CAR JAYCAR This one gives from ±1.2V to ±18.5 volts<at> 1.7 amps between ±3V and ±10V. ' CAR JAYCAR Above 10V the available current reduces to 200 milliamps at ±18V. ' CARJAYCAR Cat. KC-5022 'CAR JAYCAR 'CAR JAYCAR Ref: Silicon Chip Jan '88 'CAR JAYCAR Are you tired of the sound of your telephone 'CAR JAYCAR 'CAR JAYCAR bells? You can change to a modern sounding Ref: Silicon Chip February 1988 'CAR JAYCAR chime by building this simple module. 'CAR JAYCAR This refined car burglar alarm has just about every feature you could want and Cat. KC-5015 'CAR JAYCAR is easy to build. 'CAR JAYCAR Cat. KC-5021 'CAR JAYCAR 'CAR JAYCAR ·cAR JAYCAR ·c AR JAYCAR ·cAR JAYCAR Ref: Silicon Chip November 1987 ·cAR JAYCAR Ref: Silicon Chip December 1987 Ad.i.pt a surplus car radio/cassette player for CAR JAYCAR KIT 1 use in your home. CAR JAYCAR This multipurpose circuit can be used as a speed Cat. KC-5012 CAR JAYCAR control for electric drills or fans, as a power CAR JAYCAR controller for electric blankets or soldering irons, CAR JAYCAR CAR JAYCAR or as a table lamp dimmer. CAR JAYCAR Complete kit includes pre-asserrbled PC board, CAR JAYCAR box and front panel, mains cable, plug and socket. CAR JAYCAR Cat. KC-5016 CAR JAYCAR CAR JAYCAR CAR JAYCAR CAR JAYCAR KIT 2 UNIVERSAL SPEED/LIGHT/ CAR JAYCAR CAR JAYCAR HEAT CONTROLLER· CAR JAYCAR SHORT FORM CAR JAYCAR As used in the above kit. It is available separately CAR JAYCAR CAR JAYCAR tt you wish to mount in a piece of equipment. CAR JAYCAR Cat. KJ-5522 CAR JAYCAR CAR JAYCAR CAR JAYCAR CAR JAYCAR CAR JAYCAR Ref: Silicon Chip March 1988 CAR JAYCAR When you pick up the phone this simple circuit cuts the extension dead. Stiopping CAR JAYCAR them from listening in or dialling out. CAR JAYCAR Cat. KC-5025 CAR JAYCAR CAR JAYCAR CAR JAYCAR CAR JAYCAR GAR JAYCAR Ref: Silicon Chip CAR JAYC AR Build this circu it and you can turn your ca(s burglar alarm on and off by pressing CAR JAYCAR the button on a small keyring transmitter. CAR JAYCAR CAR JAYCAR Cat. KC-5026 CAR JAYCAR CAR JAYCAR CAR JAYCAR ' AR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYC, ~AR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAA JAYCAR JAYCAR JAYCAA JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYC, ' AR JAYCAA JAYCAA JAYCAR JAYCAR JAYCAA JAYCAA JAYCAA JAYCAA JAYCAR JAYCAA JAYCAA JAYCAA JAYCAA JAYCAR JAYCAA JAYCAA JAYCAR JAYCAA JAYCAA JAYCAR JAYCAR JAYC, ~ AY.CAB....JAYCAB IA YCAB IAYCA..R .JAYCAB IAYCAR IAYCAB .I AY..CAELJ..AYCA.8...A Y CAA IAYCAA IAYCAA IAYCAA IA YC A~ P IAVC A □ I AY CAP I AYCAA I AYC AC J AV("A.C_..LA..V r'A.D...._1.A.!LC.,_ Jaycar No. I for Silicon Chip Kits 50 an~ 100W Amp Modules with Polyswitch Speaker Protection Modem End-of-File Indicator $12.95 50WATT $32.95 $9.95 100WATT $38.95 $99.80 for stereo 100W modules with full speaker protection Sub Carrier Adaptor for FM Tuners 1GHz Digital Frequency Meter $22.95 $299 Dual Tracking Power Supply $99.95 Telephone Ringer Protector Car Alarm $19.95 Car Stereo in your Home $79.50 Universal Speed Controller $28.95 ALL FOR $18.95 A $9.95 Telephone Line Grabber $21.99 UHF Remote Switch for your Car Burglar Alarm $33.95 JAvcARJAvcARJAvcARJAYcARJAYcARJAYcARJAvcARJAvcARJAvcARJAvcARJAYcARJAvcARJAvcARJAvcAR~AvcARJAvcARJAvcARJAYcARJAY cARJAvcAR JAYCARJAYcARJ; JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR .JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAY CA R J1 JAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCA R JAYCARJAYCAR JAYCAR JAYCARJAYCAR J, JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC, Ref: Silicon Chip February 1988 JAYCAR JAYC, This project will sense a door opening in a large JAYCAR JAYC. Ref: Silicon Chip November 1987 Ref: Silicon Chip Feb '88 or small room and will sound a two-tone chime. Ref: Silicon Chip December 1987 JAYCAR JAYC. Plugs directly into your digltal This low ohms tester plugs straight Cat. KC-5020 This 24V to 12V converter can deliver JAYCAR JAYC, multimeter. Plug the unknown into the terminals of your digital JAYCAR JAYC. upto 5 amps. capacitor into the test terminals multimeter, and can accuratelY' JAYCAR JAYC, Cat. KC-5017 and read the value In picofarads (pF) measure resistance values from 1k JA'l'CAR JAYC. JAYCAR JAYC, or microfarads (uF) . ohms down to 0.01 ohms. JAYCAR JAYC Cat. KC-5010 Cat. KCC -5023 JAYC: JAYCAR JAYC. JAYCAR JAYC. JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC. JAYCAR JAYC, JAYCAR JAYC, JAYCAR JAYC. JAYCAR JAYC, JAYCAR JAYC. TURN YOUR SURPLUS STOCK JAYCAR JAYC. INTO CASH!! JAYCAR JAYC, JAYCAR JAYC. Jaycar will purchase your surplus stocks of JAYCAR JAYC. components and equipment. We are JAYCAR JAYC. continually on the lookout for sources of prime JAYCAR JAYC, quallty merchandise. JAYCAR JAYC. JAYCAR JAYC. CALL GARY JOHNSTON OR JAYCARJAYC BRUCE ROUTLEY NOW ON (02) JAYCAR JAYC. JAYCAR JAYC 747 2022 JAYCAR JAYC JAYCAR .JAYCAR JAYC JAYCAR JAYC JAYCAR JAYC JAYCAR JAYC JAYCAR JAYC JAYCAR JAYC JAYCAR JAYC JAYCAR JAYC JAYCAR JAYC The low cost way to build prototypes or one-off projects! JAYCAR JAYC We now stock 3 sizes of Phenolic board that has a matrix of punched holes on a 0. 1• This device simply plugs into the banana sockets of your digital multimeter. It will give JAYCAR JAYC (2.5mm) pitch with a 'donut' of tin plated copper around each hole. Each donut is an output of 1mV (millivolt) for every degree increase in temperature. This means that JAYCAR JAYC separated from Its neighbours by about a 0.5mm gap. This effectively isolates each pad on, say, your 200mV DC range you can read the temperature on the multimeter JAYCAR JAYC but also makes It easy to brifge solder across to make interconnections . Each board also JAYCAR JAYC directly. You can switch from •c to •F. A very high qualtty probe with semiconductor has 'fingers' on opposite ends. These can be used to connect to and from the board or to JAYCAR JAYC sensor in the tip. A generous curl cord connects the probe and adaptor housing. JAYCAR JAYC a card edge connector. Finally the non-solder side of the board has an alpha-numeric grid Requires 9V cell. JAYCAR JAYC printed on it to assist in component Identification board layout. JAYCAR JAYC 3 SIZES: SPECIFICATIONS: JAYCAR JAYC SMALL 95 x 72mm, 25 x 30 holes (750) Linear Voltage Output: 1mV/°C or 1mV/°F JAYCAR JAYC 3.6mm edge pitch JAYCAR JAYC Meaurement Range: -50°c to + 15o•c or -58°F to 302°F JAYCAR JAYC Accuracy : ±0.5°C or±1°F Cat. HP-9550 JAYCAR JAYC Sensor: Semiconductor type JAYCAR JAYC Power: 006P 9V battery MEDIUM 140 x 95mm, 29 x 50 holes (1450) JAYCAR JAYC Current Consumption : 2mAtypical 2.5mm edge pitch JAYCAR JAYC Response Time: From 23°C to 99.9°C 30 sec in stirring water JAYCAR JAYC JAYCAR JAYC Battery Check: "LOBAr- LED lights automallcally when battery Cat. HP-9552 JAYCAR JAYC is exhausted LARGE 210 x 78mm. 24 x 67 holes (1608) JAYCAR JAYC Dimension: Probe: F5mm x L 160mm JAYCAR JAYC 3.6mm edge pitch Adaptor: 38(W) x 70(L) x 39(H)mm JAYCAR JAYC Wire: 3.5 metres retractable cord JAY CAR JAY.C Cat. HP-9554 Weight: 120 grams JAYCAR JAY( JAYCAR JAYC Cat. QM-1590 JAYCAR JAYC JAYCAR JAYC Twin Coax Chassis Socket JAYCAR JAYC JAYCAR JAYC (as u IBM and other computers) JAYCAR JAY( Twin Coax Male Plug cat. PS-0672 JAYCAR JAYC (as used in IBM and other computers) JAYCAR JAY( JAYCAR JAYC cat. PP-0610 JAYCAR JAY( n'.Nl'le!J,lf~ ~1$,l~ Ol.-'Tf>i:JT -11$ft"~ •~~ JAYCAR JAY( ~ arY on ~a<1rf lfl!t¥f"F · · ·· 1 . JAYCAR JAYC ii) Tf~R.lTUflE A0.4PTOA MICMlCf" 10+ $ 8.95 ea . . JAYCAR JAYC JAYCAR JAYC JAYCAR JAY( JAYCAR JAYC JAYCAR JAY( JAYCAR JAY( JAYCAR JAY( JAYCAR JAY( JAYCAR JAY( JAYCAR JAY( JAYCAR JAYC JAYCAR JAY( JAYCAR JAY( JAYCAR JAYC JAYCAR JAY( JAYCAR JAY( Multimeter not included JAYCAR JAY( JAYCAR JAYC SAVE $22.55 OVER BUYING INDIVIDUAL PARTSI JAYCAR JAYC Don't ever be short of that resistor again. Jaycar now has available 7 different JAYCAR JAY( packs of 1/4W 5% resistors available. JAYCAR JAYC Each pack contains 10 of each value, and packs cover the complete range from 1 ohm to 10M ohms. JAYCAR JAYC JAYCAR JAY( Values (10 of each) 1. 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2 ohms Total 120 Cat. RR-1690 $3.95 JAYCAR JAYC Values (10 of each) 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 ohms Total 120 Cat. RR-1691 $3.95 JAYCAR JAY( Values (10 of each) 100,120,150,180,220,270, 330,390,470,560,680,820 ohms Total 120 Cat. RR-1692 $3.95 JAYCAR JAYC Values (10 of each) 1k, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2k Total 120 Cat. RR-1693 $3.95 JAYCAR JAYC Values (10 of each) 10k, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82k Total 120 Cat. RR-1694 $3.95 .IAYCAR JAYC JAYCAR JAYC Values (10 of each) 100k, 120, 150, 180,220,270,330,390,470,560,680, 820k Total 120 Cat. RR-1695 $3.95 JAYCAR JAY( Values (10 of each) 1M, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2, t0M Total 130 Cat. RR- 1696 $3.95 JAYCAR JAY( 1 pack of each of the above. 7 packs in all giving a total of 850 resistors 10 of each value Cat. RR-1697 VALUE AT $19.95 SAVE $7.70 over buying individual packs JAYCAR JAY( JAYCAR JAYC JAYCAR JAYC JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJ AYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJ AYCARJAYCAR JAYCAR JAY~AR JAYCAR .JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAY CAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYC.A.R JAY•~AR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJ~~ ~~~~:i:.£~~ ~~~~~~ ~~~• :AB Capacitance Adaptor for your DMM Low Ohms Tester for DMM 24V to 12V Converter for Trucks Door Minder $37.50 $59.00 $27.95 j!~g:~ $29.95 j!~g Temperature Probe Adaptor for Digital Multimeters Universal Pre-Punched Experimenters Boards $2.45 $3.95 $4.50 $59.95 Twinax ~mo·n: I ~~ $9.95 ea $ . 11 95 ea """ --~ ;. _ }/!ii"• , · 11 , --------"'· .;~.;,ir. -· . __ ----1988 CATALOGUE If you missed out on obtaining a copy of our NEW 132 page Engineering Catalogue :• Call into any of our stores - only $1.00 • Send $2 to PO Box 185 Concord 2137 and we will poast one to you Jaycar Introduces the Easy Way to Buy 1/4 watt Resistors A GREATWAYTONEVER BE OUT OF THAT ODD RESISTOR AND SAVE A PACKET AT THE SAME TIME!! . - . - - .. . - · . . - · .. . -· . . -• .. , - · ., -• .. . ,n , , ....,, ., , v n , ..., ,...., , , ..,,...., 1 vn11 un 1vnn un I VMn JMT\JMM JATVA H J A T L,AH JAYL,;AH JAYG/ 'CARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJAYCt 'CAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCA R JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCI ' CARJAYCA RJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJ AYCAR JAYCARJAYC; ' CAR JAYCAR ' CAR JAYCAR ' CAR JAYCAR 'CAR JAYCAR ' CAR JAYCAR You don't see this very often. A pack A pack of at least 35 potentiometers 'CAR JAYCAR Finally available, our updated guitar speaker with exof 20 sliders in assorted values which includes slider pots - single and 'CAR JAYCAR tended frequency response. Especially suited for not 'CAR JAYCAR between 5k and 500k. 20 for $1 O. dual, an assortment of pots and tab only Bass guitar but Rythm and Lead as well. 'CAR JAYCAR. That's only 50,t eachl The majority in style pots with assorted shafts and a Resonant Freq. 60Hz (was SOHz) 'CAR JAYCAR selection of quality 5mm vertical sealed the pack are dual gang which have 'CAR JAYCAR Impedance 8 ohm been selling for $5.50 each . A typical trirrpots and open 5mm horizontal 'CAR JAYCAR Freq. Response 60 - 5,000Hz (was 80-4kHz) Black with interlocking collar. styles. This represents exceelent value pack includes values such as Sk, 50k, 'CAR JAYCAR Power Handling 100 watts RMS Cat. HP-1102 packet 20 1OOk, 250k, and 500k in 45 and 'CAR JAYCAR at only $10. Magnet Weight 40oz CAR JAYCAR 60mm lengths in single and dual Cat. RP-3902 Net Weight 361 Og (was 3520g) CAR JAYCAR styles. Sensitivity 102dB CAR JAYCAR Cat. HP-1103 packet 100 GET ONE WHILE THEY LAST! CAR JAYCAR But the best news is the price - NO INCREASE Cat. RP-3903 CAR JAYCAR Cat. CG-2380 CAR JAYCAR CAR JAYCAR CAR JAYCAR • (j CAR JAYCAR The great new LED Bezels are made of CAR JAYCAR ~ black plastic and are supplied in 2 parts. CAR JAYCAR Sirrply push part A into the panel (you CAR JAYCAR \ ~ CARJAYCAR will need a 10mm hole), then put the CARJAYCAR LED Into part B and insert part B (with It "' ,., ';WO .. . • CARJAYCAR LED) Into part A for a tight flt. You end Q <;, CARJAYCAR up with a very professional LED bezel at CARJAYCAR about 1/4 the price of chrome ones. CARJAYCAR ALSO. If you have the need for a hole in CARJAYCAR CARJAYCAR a panel up until now It has been CAR JAYCAR extremely hard to disguise it. Simply CAR JAYCAR mount one of these without the LED. CARJAYCAR Ideal for internal mounted buzzers, CAR JAYCAR lamps, etc. CAR JAYCAR Cat. HP-1105 packet 10 CAR JAYCAR CAR JAYCA,R MADE IN THE USA ::AR JAYCAR ::AR JAYCAR This high quality filter is basically a metal box with soldered on lid . On one side is an Cat. HP-1106 packet 100 ::AR JAYCAR lEC-320 type recessed chass is plug. The box mounts on the inside of a cabinet with ::AR JAYCAR an approprlate·hole for the IEC connector and two mounting screws .The filter is ::AR JAYCAR rated at 240V 3 amps 1/4" O.C. type terminals are on the top for simple internal ::AR JAYCAR mains connection. '.:AR JAYCAR '.:AR JAYCAR SPECS :;AR JAYCAR 115-250V AC Input :;AR JAYCAR 47 • 63Hz :;AR JAYCAR Black, requires a 4mm panel hole. 3 amp (continuous) :;AR JAYCAR Slrrply push clip Into panel and Insert Dims: 65(0) X 45(H) :AR JAYCAR LED, excluding terminals :AR JAYCAR :AR JAYCAR x53(W)mm Cat.HP-1100 :AR JAYCAR Very high quality. :AR JAYCAR Cat. MS-4004 :AR JAYCAR Cat.HP-1101 • · ---- :AR JAYCAR :AR JAYCAR pk100 ;AR JAYCAR 10 up $17.95 ea ;AR JAYCAR ;AR JAYCAR APRIL ONLY ;AR JAYCAR :AR JAYCAR :AR JAYCAR The Sunvent ls a high capacity solar cell and DC motor ;AR JAYCAR powered fan in a well designed cowling. The cowling :AR JAYCAR 1 O+ $12.95 ea has been cleverly designed to keep waiter out and :AR JAYCAR back draughts out. :AR JAYCAR :AR JAYCAR Simply cut a 120mm hole Jn a oulkhead or deck· or : AR JAYCAR whatever - and the Sunvent will remove stale damp air : AR JAYCAR and cut down mildew growth. lt will extract dangerous : AR JAYCAR LP gas or petrol fumes safely as the motor is sealed. :AR JAYCAR Great replacement electret mic inserts for tape The Sunvent is at Its best in bright sunlight but will work : AR JAYCAR quite well even on bright cloudy days. It will move recorders, etc. Handy for hobby proj ects. Includes :AR JAYCAR data sheet and applications circuit. Operates from a :AR JAYCAR about 35 cubic metres of air every half hour in good :AR JAYCAR conditions. Supplied with cover to turn off C8lls and single 1.5V battery. 10mm diameter. 50Hz - 15kHz. :AR JAYCAR Cat. AM-4010 stop all airflow. :AR JAYCAR • Boats :AR JAYCAR • Caravans :AR JAYCAR • Port-a-Loos :AR JAYCAR 1 O or more $1.65 each :AR JAYCAR • Greenhouses :AR JAYCAR • Sheds :AR JAYCAR • Holiday homes :AR JAYCAR • Backyard dunnies :AR JAYCAR • Kitchens :AR JAYCAR • Weekenders etc :AR JAYCAR .AR JAYCAR Cat. YX-2500 -AR JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR AR JAYCAR LESS THAN HALF AR JAYCAR THE PRJCE OF AR JAYCAR NEAREST AR JAYCAR EUF.OPEAN MADE AR JAYCAR AR JAYCAR EOUJVALENTI AR JAYCAR AR JAYCAR This motor measuring 38 dia and 35mm AR JAYCAR long (plus shaft t 0mm long) has high AR JAYCAR torque, modest current consumption. It is AR JAYCAR Ideal as a cassett e deck replacement AR JAYCAR motor. lt is very high in quality - the AR JAYCAR motor itself is rubber mounted into an AR JAYCAR AR JAYCAR outer case, with scree ned power leads. l\R JAYCAR Ideal also for toys, robotics , etc. 2400 l\R JAYCAR rpm . No mounting plate. l\R JAYCAR Cat. YM -2702 l\R JAYCAR l\R JAYCAR l\R JAYCAR LED Mounting Hardware 12" Guitar Speaker Mixed Pots Slider Pots 5mm Clips $2.20 ■i $8.9s $10 G •Jr===-: I 5mm Bezels • $89.50 ., ONLY $10.00 ' . 1'. ~r ·-~~ •_·ts,' ... • " IEC-Type Mains Input Filter $2.99 $26.95 [D ~ E::3 3mm Clips $2.2Qpk20 I) • · ·"- NORMALLY $19.95 ea $8.95 Solar Powered Exhaust Ventilator $13.95 Mic Insert $1.95 1988 CATALOGUE If you missed out on obtaining a copy of our NEW 132 page Engineering Catalogue:• Call into any of our stores - only $1.00 • Send $2 to PO Box 185 Concord 2137 and we will post one to you $49.95 6V 2400 rpm Cassette Player Motor SCOOP BUY! ONLY $1 .00 ea JAYCAR No.1 FOR UNIQUE AND INTERESTING PRODUCTS 10+ 95tt ea ~~ j !~g !~JAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCAR JAYCARJAYCt l\R JAYCAR JAYCA R JAYCARjAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJAYCARJ AY CAR JAYCARJAYC1 rn IAYr.A R .IAYC: AR .J AYC:AR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAY.CAR JAYCAR JAYCAR JAYC/1.R JAYCAR JAYCAR JAYCAR JAYC AR JAYCAR JAVCAR IAYCAR IAYCA B IAYC AB 1AYC, JAYCARJAYCAHJAYCAHJAYGAKJAYGAHJAYCAHJAYCAHJAYCAHJAYCAHJAYCAHJAYCAHJAYCAHJAYCAHJAYLAHJAYCAHJAYCAH JAYCAR JAYCAR JAYCAR JAYCAR JAYCAA JAYCAA JAYCAR JAYCAA JAYCAA JAYCAA JAYCAR JAYCAA JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAA JAYCAR JAYCAR JAYCAA JAYCAR JAYCAR JAYCAR JAYCAR JAYCAA JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR Direct lmp·ort PCB Mounting Potentiometers with Imperial Standard Shaft & Bushings Breadboards Jaycar breadboards are a convenient and economic way to build circuits and test parts without soldering. Components can be then reused many times. Made from ABS Polymer. Internal contact terminals are made of alloy of silver and nickel and then plated. Resistance is under 1 milliohm at 1kHz. LIFETIME GUARANTEE After suffering enormous supply frustration in recent years we have decided to direct import quallty potentiometers to our rigid engineering specttications. The potentiometers are full size - 24mm diameter types - not the dinky 16mm ones that you sometimes see these days. They also have genuine 6.35mm (1/4") shafts with a flat machined 25% of the diameter for grubscrews or interference fit knob mounting. The shaft is a generous 38mm long. The bush is a 318'' 32 T.H.D. type which we believe is necessary for good fixing to a panel. Many pots these days have 7mm - and less - bushes. Another important feature of the pots is their PCB mounl capabillty. The pins are rigidly mounted on phenolic with the centre pin offset from the two outer terminals. When soldered into a PCB, the pot is quite rigidly held on its own. Dual gang pots are held in 6 places and require no extra mechanical mounting assistance. The pins are large enough to terminate screened cable, etc., tt the job requires hard wiring. An engineering drawing appears below. You may safely use it to design PCB artwork etc., as we have standardised on this design. CUSTOMERS PLEASE NOTE: While we are introducing stock of our new pots there will naturally be a transition period where old stock will remain. This may not be a cause for concern but if it is, please ASK for the new product. (The cat numbers will be the same.) Log Single Gang RP-3594 RP-3698 AP-3S~9 RP-385ll RP-361tfi RP-3Sit8k AP-3880k RP-36QQk RP-351111 RP-381i!l JAYLAHJAYCAHJAYCAHJAYCAK JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAA JAY CAR JAYCAR JAYCAR JAYCAR JAYCAR Breadboard Specifications Cat. No Length Width PB-8810 172 p B-8812 172 p 8-8814 172 p B-8816 224 p B-8818 240 p B-8820 264 • Connected •• Weight Tie Points 13 10 39 10 65 10 150 20 195 2 240 21 Capacity••• Pins 100 640 840 1680 2420 3260 5 25 Binding Con• ton• Post Term Bus 4 128 128 8 256 16 3 384 20 4 512 28 4 IC Price cap·· 14".. $3.75 9 $10. 75 9 $17.50 18 $39.95 27 $57.50 36 $69.95 Linear Double Gang Cat. No RP-3706 RP-3708 RP-3710 AP-3712 AP-3716 AP-3718 Type 10k 25k 50k 100k 500k 1M $3.25 ea 10 or more $3.00each Log Double Gang ea $1.65 10 or more $1.40 each AP-3858 1Ok anti log Linear Single Gang Cat. No RP-3502 RP-3504 RP-3508 RP-3510 RP-3514 RP-3516 RP-3518 RP-3520 RP-3522 RP-3524 RP-3526 Type 500A 1k 5k 10k 25k Cat. No RP-3756 RP-3758 AP-3760 RP-3762 RP-3766 RP-3768 RP-3785 Type 10k 25k $3.25 ea 50k 10 or more $3.00 each 100k 500k 1M 250k Jaycar Soldering Kit Designed for general purpose soldering. This kit includes a 30 wan 240V soldering iron and quality metal stand with sponge, a length of solder and a roll of solderwick. Cat. TS-1850 $1.65 ea $31.95 10 or more $1.40 each 50k 100k 250k 500k 1M 2M ~~ rft:.;•,a ~~ ~ TURN YOUR SURPLUS STOCK INTO CASH!! Jaycar will purchase your surplus stocks of componen1s and equipment. We are continually on the lookout for sources of prime quality merchandise. \ \ ~ a-32Nff 1///////////////////////////////////////////~/////////////////////////////////~Y///.////////////////////////////////,{ff"//////////////////////4,~~g:~ j! ~SYDNEY - CITY 117YorkSt.(02)2671614• ~ HEAD OFFICE ~ YCAR JA / ~ v,CARLINGFORD /,.-,.\,-,\ - ■, I ~ CALL GARY JOHNSTON OR BRUCE ROUTLEY NOW ON (02) 747 2022 JAYCAK JAY Al JAYCAR JAY' AI JAYCAR JAY Al JAYCA R JAY ;AI JAYCARJA· JAYCARJA' JAYCARJA' JAYCAR JA' JAYCAR JA JAYCARJA JAYCARJA JAYCARJA JAYCARJ A JAYCARJ A JAYCARJA JAYCARJA JAYCARJA JAYCAR JA JAYCAR JA JAYCARJA JAYCAR JA JAYCARJA JAYCARJA JAYCAR JA JAY CARJA JAYCARJA JAYC AR JA JAYC ARJ A JAYCARJA JAYCAR JA JAYCARJA JAYCARJA JAYCARJA JAYCARJA JAYCAR JA JAYCAR JA JAYCAA JA JAYCARJA JAYCAR JA JAYCAR JA JAYCAR JA JAYCAR JA JAYCAR JA JAYCAR JA JAYCARJ A JAYCARJ A JAYCARJ A JAY CAR JA JAYCARJA JAYCAR JA JAYCARJA JAYCARJA JAYCARJA JAYCARJ A JAYCAR JA JAYCAR JA JAYCAR JA JAYCAR JA JAYCARJA JAYCARJA JAYCAR JA JAYCAR JA JAY CAR JA JAYCAR JA JAYCARJ A JAYCAR JA JAYCARJA JAYCARJA JAYCARJA JAYCARJA JAYCARJA JAYCARJA JAYCARJA JAYCARJA JAYCAR JA JAYCARJA JAYCARJA JAYCAR JA JAYCARJ A JAYCARJ A JAYCARJ A JAYCARJ A JAYCARJ A JAYCARJ A JAYCAR JA JAYCAR JA JAYCARJA JAYCARJA JAYCARJ A JAYCARJ A JAYCA RJ A JAYCA RJ A JAYCAR JA JAYCARJA JAYCAR JA JAYCARJA JAYCARJA JAYCARJA JAYCAR JA JAYCARJ A JAYC ARJ A JAYCARJA JAYCARJ A (MasterCard.I 1 ·./ '-..._ ., ·---· VISA ~ ■lililiil• ~~J / ~ ~CONCORD ½ l ~HURSTVILLE POST & PACKING ~GORE HILL $5 $9.99 ~ 2.00 ~ $10 $24 99 $ 3.75 ~ BURANDA QLD $25 $4 9.99 $ 4.5o % $50 $99.99 $ 6.50 ~ OVEA$100 $10.00 MELBOURNE-CITY ROAD FREIGHT ~ IN A~:iR~~~Ri 50 ~ SPRINGVALE VIC 3 ~ AMERICAN EXPRESS Wf~fff{fffdii~~{11~«1, ~ 115 Parram atta Road ~ YCARJA ~ Concord2137 ~ (02) 747 2022 ~ YCARJ A ~ Telex72293 ~~g!~ j~ Mon-Fn B.30 - 5.30 Thurs B.30 pm - Sat 9 • 12 Cnr.Carlingford&PennantHIIIsRd(02)8724444 Mon-Fri9 -5.30Thurs8.30pm-Sat9-2pm 115ParramattaRd(02)7453077Mon-FriB.30-5.30 - SatB.30-12 121ForestRd(02)5707000Mon-Fn9-5.30Thurs8.30pm-Sat9-12 188PactticHwy cnrBellevueAve(02)4394799Mon-Fn 9 - 5.30 Sat 9 -4pm 144 Logan Rd (01393 0777M F 9 530 h 830 S 19 12 on- " • · urs · • a • Shop2,45A'BeckettSt C1ty(03)6632030 Mon-Fn 9 - 5.30 Fn 8.30 - Sat 9 - 12 887-889Springvale Road Mulgrave (03) 5471022 9 0 MAIL N~Rro~tv1l Ry~~OR·FrP H~~ ~~g!~j! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ FACSIMILE (02) 744 0767 MAIL ORDERS P.O. Box 185 CHonocoTrLd12N1E37 (02) 74 7 1888 FOR ORDERS ONLY TOLL FREE (00 8 ) 022 888 ~ YCARJA ~ YCAR JA ~~g!~ j! ~ ~ ~ ~ ~ ~ YCAR JA YCAR JA YCAR JA YCARJ A YCAR JA YCARJt 0'~g:~j~ ~ YCAR JI t'~M~ver~t11~i?'ft:~ is~;J1 12 IAYCAR .JAVCAR JAYCA R JAYCAA JAYCAR .JAYCAR .JAVCAR .JAVCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAB..,/AYCAR JAYCAR JAYCAR ~YQA_R___,/AY'_~p HEADPHONE L FOR CD PLAYERS Does your compact disc player have a headphone socket? It doesn't? How sod. Now you con correct that situation and listen to the music direct, without degrading the sound quality. 28 SILICON Cl-fll' Many CD players do not have a headphone socket which is a pity. There is a great attraction in listening to your favourite discs directly via headphones. By the same token, there is something faintly ridiculous about listening to headphones via a stereo amplifier which might have a power capability of 100 watts per channel - all that amplifier circuitry just to provide a few milliwatts. In fact, a number of smaller CD players do have the internal circuitry necessary to provide headphone drive but the headphone socket and volume control have been omitted. For most of us, the idea of any modification to a CD player, no matter how slight, will be anathema. The alternative of an external headphone amplifier is much more attractive. The headphone amplifier presented here is just about as simple as you can get without in any way prejudicing or degrading the signal quality from the CD player. It is housed in a plastic box and is powered by a 9 or 12V AC mains plugpack. Mounted on the top panel of the box is the on/off switch, a volume control knob and a standard 6.5mm stereo jack socket. On the side of the box is a 4-way RCA socket panel. This allows you to connect the headphone amplifier to the CD player and also connect the CD player signal to your existing stereo amplifier, if need be. Even if your CD player already has a headphone socket, you may want to build the headphone amplifier presented here. Some CD players do not have a level control on their headphone socket, or perhaps the maximum output level IFIER RIGHT~-:;i OUTPUT I I +17V II I RIGHT(} INPUT "1, __ - 22pF r-- HEADPHONES ~ .,. 220k .,. By JOHN CLARKE & LEO SIMPSON .,.. LEFT ~ - ; . OUTPUT -]iI +17V II Main Features • Adds headphone outputs to any CD player • Volume control • Simple design uses only two low noise op amps • Suitable for all headphones, low or high impedance • Simple power supply without 3-terminal regulators • Powered by 9V to 1 2V AC plugpack • Signal-to-noise ratio better than 95d8 . • Harmonic distortion better than LE F T e INPUT --- 22pF VOLUME VR1b 50k LOG 220k .,. -:- POWER 0--0 12VAC PLUG-PACK 01 1N4002 ~-,-..,1-Y,4-....,--------+17V 81 1000 25VW + 0 .001 % • Housed in plastic zippy box -------------11v 02 1N4002 is not sufficient to drive your favourite headphones. Either way, the headphone amplifier presented here could be a big improvement as it gives more than adequate drive signal. How it works The circuit is based on two Signetics 5534 low noise bipolar op amps, one for each channel, and these drive the phones directly. Most op amps could not do this job unaided but the 5534 is unusual in that, besides being a very low noise op amp, it can also drive 6000 loads at full output swing. This means that it is capable of delivering more output current than most op amps and this is the characteristic we are depending on to make the circuit work. Each op amp is connected as a non-inverting amplifier stage with a gain of approximately 3.7, as set by the 22k0 and 82k0 feedback HEADPHONE AMPLIFIER SC1-1-688 Fig.1: the circuit uses two 5534 low noise op amps to give excellent headphone reproduction. The 5534s allow a very simple power supply to be used. resistors. Output signal to the headphones is then fed via a 2200 resistor in each channel. This resistor limits the current in the event of a short-circuit or overdrive to a value which is safe for both headphones and the op amps. As such, the headphone amplifier can drive just about all headphones to ear-shattering volume. This applies whether the phones have a low impedance of 80 or 320 or a high impedance such as 6000 or 2k0. The input signal to each amplifier channel is fed via a dual ganged pot and then coupled via a O. lµF capacitor to the non-inverting input of each op amp. The 22pF compensation capacitor across pins 5 and 8 keep the op amps stable at the selected level of gain. The power supply is crude but effective. It consists of a 9 to 12V AC plugpack as already mentioned. This feeds a positive and negative halfwave rectifier to produce positive and negative supply rails of about 17 volts, depending on the AC input voltage. The resulting DC voltages are filtered by 1000µF electrolytic capacitors. Normally, an op amp circuit such as this would use 3-terminal regulators to provide balanced supply rails of ± 15 volts. But the 5534 op amps are rated for operation up to ± 22V volts which means that we can dispense with 3-terminal regulators. The op amps also have excellent power supply rejection APRIL 1988 29 PARTS LIST 1 PCB code, SC1-1 -488, 84 x 44mm; or Veroboard, 84 x 48mm 1 plastic case, 130 x 68 x 43mm (Altronics H-0203 or Jaycar HB-6013) 1 front panel artwork 1 rear panel artwork 1 4-way RCA panel socket 1 dual ganged 50k0 log pot 1 SPOT switch 1 knob 1 stereo 6.5mm headphone panel socket ~ 8 28 Semiconductors 2 NE5534 op amps 2 1 N4002 diodes 1 red LED ( VAC PLUG-PACK Capacitors 2 1 OOOµF 25VW PC electrolytic 2 0.1 µF metallised polyester 2 22pF ceramic B A \ ~ LEFT RIGHT INPUT LEFT RIGHT OUTPUT Fig.2: here is the wiring diagram for the PCB version. Use shielded cable for the connections to the volume control and the input and output sockets. ' , 1 FROM PLUG-PACK VIA S1 LEFT INPUT 01 K .,.....,_..._,-;-~A GND R L TD HEADPHONE SOCKET Fig.3: parts layout for the alternative Veroboard version. Fig.4: actual size artwork for the printed circuit board. 30 SILICON CHIP Miscellaneous Hookup wire, shielded cable, solder, screws, nuts, etc . . ' ,·. \- Resistors (0 .25W, 5%) 2 x 220k0, 2 X 22k0, 2 X 8 .2k0, 1 X 6.8k0, 2 X 2200 which means that any variations in the unregulated 17V supplies are ignored. Result - extremely quiet and hum-free amplifiers. A light emitting diode connected in series with a 6.8k0 resistor across the ± 17V rails acts as power indicator. Construction We built our headphone amplifier into a plastic case measuring 130 x 69 x 45mm (Altronics Cat No H-0203). The circuitry can be assembled onto a printed circuit board (PCB) measuring 84 x 44mm (code SCl-1-488) or on a piece of Veroboard measuring 84 x 48mm. Whether you use a PCB or Veroboard for the project, it will not take long to assemble. Make sure you follow the relevant wiring diagram carefully. For the Veroboard version, the tracks can be cut using a sharp drill bit. Use screened cable for the wiring between the input sockets and the volume control and to the input on This view view clearly shows the shielded cable and other wiring connections to the PCB. It may be compact but it can drive most stereo headphones to ear-splitting volume. r:- 0 ~ ,- I w 0 ffi :ii: 3 ~ • u::: ::J Q. If your headphones are fitted with a 3.5mm plug you will need a 6.5mm adaptor as shown with these MHD3A phones from Arista. :i <( w the PCB. Note that the shields of all cables are connected, either to the sockets, dual pot or at the printed board. We used a 6.5mm stereo socket for the headphone jack. If you have headphones with 3.5mm plugs you may prefer to use a 3.5mm stereo socket. But be warned - most 3.5mm sockets that are available are flimsy affairs which do not stand up well to prolonged use and are difficult to solder. In those instances, we suggest you install the 6.5mm socket specified and then use a 6.5mmto-3.5mm adaptor plug. (Some headphones are supplied with these adaptor plugs.} We suggest that the AC plugpack be permanently wired to the headphone amplifier as jack sockets for power supplies can give problems. :::c: • z 0 Q. C 0 ~ :::c: ffi z 0 0 0 J: 25 ~ :c L:. 0 0 ~..:..1L _J Fig.5: full-size artworks for the front and rear panels. When the headphone amplifier is finished, apply power and plug in your phones. There should be no sound from the phones, even with the volume control flat out. Now wind down the volume control. connect your CD player and sit back to enjoy the music. ~ 1\l'llll. /!lll/l 31 MK-ARO '111 RO'I*I'LE FOR MODEL ROADS Want to build a walk-around throttle for your model railroad layout? This one offers a host of features including pulse power, inertia (momentum), braking and full overload protection. By LEO SIMPSON & JOHN CLARKE 32 SILICON Cll/1' Over the years we have seen a number of solid state throttles for model railroad layouts but none matches the circuit presented here for features and versatility. For example, consider the walk-around throttle feature. These days, few model railroad enthusiasts want to be tied to a fixed console in order to operate their trains. They want a walk-around throttle so that they can observe the train closely while they are controlling it. The walk-around throttle concept is simple - just a small box on the end of a lead which has a knob to vary the speed and perhaps a couple of switches to provide direction (forward/reverse) and braking. As such, it is a pretty simple concept but what if you have a large layout? You don't want to have a very long lead otherwise it will get tangled and you will trip over it. No, you want to be able to plug the handheld controller into various sockets around the layout as the train moves over the tracks. And when you disconnect the controller from one socket in order to move to the next, you don't want the train to suddenly speed up or stop; the train should continue at its pre-determined speed; ie, the controller should have memory. Having made such a point about the walk-around concept, as you might expect, our circuit has this desirable feature along with those listed in the accompanying panel. Let's talk about some of these features. Main Features • Pulse power for smooth and reliable low speed operation. • Monitoring of motor back-EMF for excellent speed regulation . • Adequate power for double and triple heading of locos. • Inertia (momentum) so that the model acts as though it had the sizable inertia of a real train . • Full overload protection in- eluding visible and audible overload indicators (short circuit duration: one minute) . • Power and track/direction LED indicators. • Provision for maximum output voltage adjustment (to suit Z scale). • Fixed 1 2V DC output for accessories. ,.., ,.., Vo I \ \ I \ I \ I \ I \ I ' \ \ lb) Pulse power Pulse power in model train controllers is not new although to most most model train enthusiasts pulse power means something different to what is used in our circuit. We'll set the record straight on this point before going any further. To do so, we need to briefly review the current state of the art. Most basic model train supplies consist of a low voltage transformer feeding a bridge rectifier to produce unfiltered DC as shown in Fig. l(a). This unfiltered DC voltage is then varied by a simple transistor or resistor controller to set the train speed. Fig.l(b) depicts the waveform when the controller is set for a low train speed. Now the problem with this basic approach is that when the controller is set for low speed, the output voltage is low, as you'd expect. This means that when the loco wheels and track are not scupulously clean (they never are), the train may have trouble starting or may run jerkily. Designers of commercial model train controllers have taken a number of approaches to improve the situation and they all involve in- I I I I I ,.., ,.., ,,, \ I I I I I \ I I I I I I \ ,.. ' \ / I I I I I I ,.. .... \ I (d) Fig.1: most controllers operate by varying the level of an unfiltered rectified DC waveform as shown in (a), (b) & (c). An SCR controller (d) chops the fullwave rectified DC but best results come from a pulse power controller (e). creasing the peak voltage applied to the track while the average voltage for low speed settings remains low. The simplest and crudest of these approaches is to use half-wave rectified DC, as shown in Fig. l( c ). This gives a higher peak voltage for a given low speed setting but has the disadvantage that it makes the loco motors growl, particularly at low speed settings. Now this crude approach is often referred to as "pulse power" and, in the truest sense of the word, so it is but it is crude nonetheless. Some controllers with this design have a refinement(?) whereby the output voltage waveform makes a transition from halfwave rectification to full wave rectification as the speed setting is increased. It's still crude though. Another approach is to use a silicon controlled rectifier which chops the full wave rectified DC waveform to provide speed control. This approach is better but still has the disadvantage that, at low speed settings, the track voltage is still relatively low - see Fig.l(d). Then there's the way our circuit does it: the proper way, as shown in /\i'HII, Hl[lfl 33 +12V +12V 100k 100k VT 100k VP SPEED A.Iv\ OSCILLATOR Fig;2: basic pulse power control circuit. IC1d is wired as a Schmitt trigger oscillator while IC2a is wired as a comparator. The output (Vp) is a 200Hz pulse waveform with pulse width determined by the setting of the speed control pot. VT /'( /\ I\ "/1/K} I . nn XT/\/\ VP-VP~...____.~....______.~.___r (a) HIGH VOLTAGE (b) LOW VOLTAGE Fig.3: how the output of IC2a varies with the setting of the speed control pot. At higher speed settings, the output pulses are longer. Fig.1( e ). This is essentially the same method used in switchmode power supplies whereby a relatively high DC voltage is varied by rapidly switching it on and off. This means that the peak voltage across the track is always the same, regardless of the speed setting. Varying the width of the pulses applied to the loco varies the speed see Fig.l(e). In our circuit, the track voltage is about 17 or 18 volts peak. This relatively high voltage is better able to overcome poor contact resistance between the loco wheels and track and so gives much better low speed running and starting. the back-EMF (EMF stands for electromotive force, another term for voltage) is proportional to the motor speed. So the circuit monitors the backEMF of the motor and if this voltage drops, as it tends to when the loco starts lugging up a slope or whatever, the circuit actually increases its output voltage to help maintain the selected speed. We haven't overdone this feature though, so that a loco will still tend to slow down as it is loaded, but the speed regulation is certainly better than if this feedback was not included. Speed regulation Real trains have inertia, hundreds or thousands of tonnes of it. When the driver opens the throttles on his loco(s) very little happens at first. It may take many kilometres for the train to get up to operating speed and similarly, when he applies the brakes, the speed does not slacken very rapidly. By contrast, model trains have no inertia at all and when full power is Another worthwhile feature of our circuit is the speed regulation. This helps the loco to maintain its speed even though the gradient may change or the load may change, as in shunting. What happens is that the circuit monitors the back-EMF of the motor. This is the voltage the motor generates to oppose the current through it and, as it happens, 34 SILICON CHIP Inertia or momentum applied to the track, they accelerate like startled rabbits. Similarly, if power is abruptly removed from the track, they skid to a stop, which is hardly what you'd call "realistic operation". For this reason, the Railpower controller incorporates inertia circuitry so that the track voltage builds up slowly when the speed control is wound full on and drops slowly when the brake is applied. It makes the trains look a whole lot more realistic. Overload protection All model train controllers need some sort of short circuit protection because short circuits can occur quite frequently. Whether it's because a loco is derailed, or because points are faulty or because someone deliberately shorts out the rails with a screwdriver, overloads do occur. The Railpower controller has "foldback" short circuit protection (we'll explain that later) plus a LED indicator and a buzzer to indicate that an overload has occurred. Thus, it will indicate even when momentary shorts occur, as can happen when a loco is crossing points. Power output While model loco motors rarely pull much more than one amp, some model locos can pull considerably more than this, depending on whether they have smoke generators, sound systems and lighting. So if you want to double or triplehead locos or have lots of track lighting, you'll want plenty of amps. The Railpower controller has plenty, around 4 amps or so with the specified 60VA transformer. In testing the power output we ran as many as six HO locomotives simultaneously from the Railpower. Most of these locos also had internal lighting so it really did amount to a considerable load. The Railpower handled it without a murmur and without even getting warm. Current output is not the only important parameter though. While most model locos are specified to operate with a maximum of 12 volts DC, some manufacturers specify less voltage and this should not be PARTS LIST 1 PCB, code SC9-1-488, 117 x 125mm 1 50 x 20mm piece of Veroboard 1 Scotchcal label, 79 x 50mm 1 plastic case, 83 x 54 x 30mm 1 piece of aluminium, 80 x 60mm x 0 .6mm 1 1 2V 60VA transformer 2 8-way PCB terminals 1 6-way PCB terminal 2 SPDT switches 1 knob 1 grommet 1 6-way cable 1 12V buzzer Semiconductors 2 BD650 PNP power Darlington transistors 2 BD649 NPN power Darlington transistors 3 BC54 7 NPN transistors 1 BC558 PNP transistor 1 7812 12V 3-terminal regulator 4 1 N5404 3A diodes 5 1 N4148, 1 N914 diodes 2 red LEDs 1 bi-colour LED 2 LM324 quad op amps 1 4093 quad Schmitt NAND gates 1 4049 hex inverter buffers Capacitors 2 2200µF 25VW PC electrolytics 1 4 7µF 1 6VW PC electrolytic 1 10µF 16VW PC electrolytic 1 4. 7 µF 1 6VW PC electrolytic VP LOGIC IC3, IC4 FORWARD REVERSE o.rn CURRENT SENSE .,. Fig.4: the H-pack output circuit. To make the motor go in one direction, Ql and Q4 are turned on while Q2 and Q3 are kept off. For the reverse direction, Q2 and Q3 are turned on and Ql and Q4 are turned off. exceeded, to safeguard their motors. For example, Marklin Zscale (1:220) locos are specified for a maximum of 8 volts DC. The Railpower controller has provision to adjust for these specified maximum voltages. Operating principles The complete circuit shown in Fig.5 is pretty daunting to try and comprehend at first so let's have a look at the core of the circuit which is shown in Fig.2. This depicts the two key op amps which provide the pulse width modulation. ICld is wired as a Schmitt trigger oscillator while IC2a is wired as a comparator. ICld oscillates by the following action. When power is first applied Cl has no charge and the output of ICld is high. Consequently, Cl is charged via Rl until the voltage at pin 6 exceeds the voltage at pin 5. This causes the output at pin 7 to switch low and so Cl is now discharged via Rl. So Cl is alternately charged and 1 2.2µF 25VW PC electrolytic 1 2. 2µF 1 6VW PC electrolytic 2 0 .1µF metallised polyester (greencap) 1 0 .01 µF metallised polyester (greencap) Resistors (0.25W, 5%) 1 X 560k0, 1 X 220k0, 2 X 120k0, 5 x 1 OOkO, 1 x 27k0, 1 x 22k0, 2 x 1 5k0, 5 x 1 OkO, 1 x 8 .2k0, 2 x 5.6k0, 6 x 2.2k0, 6 x 1 kn, 1 x 1 oon, 1 x o. rn 5W, 1 x 1 MO miniature vertical trimpot, 1 x 220k0 miniature trimpot, 2 x 1OOkO miniature trimpots, 1 x 1 Okn linear potentiometer Miscellaneous Solder, tinned copper wire, screws, nuts, etc. discharged via Rl and the resulting waveform is a triangle (sawtooth) waveform shown as Vt in Fig.3. This waveform has an amplitude of between two and three volts peakto-peak and a frequency of about 200Hz. This triangular waveform is applied to pin 13 of IC2a which compares it with the speed voltage Vs fed to pin 12. Since IC2a is wired as a comparator its output can only be high or low, so when Vt is above Vs, the output will be low and when Vt is below Vs, the output will be high. The interaction of Vt and Vs via IC2a is shown in Fig.3. Fig.3(a) shows that when Vs is set for high speed, the output from IC2a is a series of fairly wide pulses. These give an average DC voltage across the track which is quite high. Similarly, in Fig.3(b), when Vs is set for low speed, the output from IC2a is Vp, a series of narrow pulses which have quite a low average DC voltage. H-pack output So the pulse waveform Vp is eventually transmitted to the track and loco motor via IC3, IC4 and the transistors Ql to Q6, shown on the circuit diagram Fig.5. Again, comprehending how all these devices work together is not easy so we have reproduced the output circuit in Fig.4. APRIL 1988 35 Fig.5 (right): the complete circuit diagram. All the IC and transistor numbers correspond to those shown in Figs.2 & 4. IC2c and IC2d provide the foldback current protection while ICs 3 & 4 provide logic switching to the H-pack output stage. a TO-220 plastic encapsulation but have a collector current rating of 16 amps peak (8 amps DC). Main circuit Most of the parts are accommodated on a single PCB . The four output transistors and the 3-terminal regulator are bolted to aluminium heatsinks. This shows the four transistors, Ql to Q4, in an "H" configuration with the motor of the loco connected between the two sides of the "H". IC3 and IC4 are depicted as a logic block with three inputs, one for speed which is Vp, and two for direction (forward and reverse). Fig.4 is really quite a lot more complicated than it needs to be. Instead of using six transistors and two logic ICs, we could have made do with one small signal transistor, a power transistor and a heavy duty relay, which would have reversed the track voltage for the forward/reverse mode. But while the present circuit is complicated, it does have the advantage of being cheaper and more compact than the relay/transistor combination. It also has the advantage of having memory for the direction setting. This is necessary if the walk-around control is to be unplugged at any time. Nor is there anything essentially new in the H-configuration of Fig.4. It is commonly used in industrial circuits used for motor speed and direction control. To make the motor go in one direction, Ql and Q4 are turned on while Q2 and Q3 36 SILICON CIIII' are kept off. To reverse the motor, Q2 and Q3 are turned on while Ql and Q4 are turned off. Putting it another way, for the forward motor pirection, current passes through Ql and Q4; for reverse, current passes through Q2 and Q3. In practice, for the forward direction Q4 is turned on fully and Ql is turned rapidly on and off by the pulse waveform Vp, to give speed control. Similarly, for the reverse function, Q3 is turned on continuously and Q2 is modulated by the pulse waveform Vp to give speed control. Natty, huh? Q5 and Q6 are there solely to provide voltage level translation between the logic block, IC3 and IC4, and the output transistors. This is necessary because the logic circuitry runs from + 12V while the output transistors run from + 17V. Ql to Q4 are Darlington transistors which incorporate flyback diodes connected betwen their collectors and emitters. These diodes are necessary when driving inductive loads such as motors which will tend to generate spikes from their commutators and from the pulse waveform. The Darlingtons come in Now let us relate the circuits of Fig.2 and Fig.4 to the complete circuit of Fig.5 . The circuit of Fig.4 can be seen at the righthand side of the main circuit while ICld and IC2a are roughly in the centre of the circuit. Now have a look at ICla and IClb, at the lefthand side of the circuit. These two op amps are connected as voltage followers. Their function is to buffer and reproduce the voltage from the wipers of VRl and VR2. VRl sets the maximum voltage applied to the track. This is important, particularly for Z-gauge, as mentioned earlier. VR2 sets the minimum track voltage. This is necessary because all locos have some minimum voltage below which their motors will not run. So VRl and VR2 set the overall speed range which is provided by potentiometer VR3, connected between the outputs of ICla and IClb. Inertia The speed setting from the wiper of VR3 is fed via VR4 to the 47µ,F capacitor at the non-inverting input (pin 3) of IClc. VR4 and the 47µ,F capacitor provide the inertia feature, in the following way. Consider that the speed pot VR3 is wound up to maximum. Because of the resistance of VR4, the voltage at pin 3 of IClc does not rise immediately but gradually, as the 47 µ,F capacitor charges. If VR4 is set to its high resistance condition, the circuit gives maximum inertia. The voltage across the 4 7µ,F capacitor is buffered by voltage follower IClc which feeds IC2a, via pull-down diode DL So IClc and Dl provide the voltage Vs fed to IC2a, as shown in Fig.2 and Fig.3. IClc and the 47 µ,F capacitor also provide a "speed memory" in case the "'-l w 0:, 0:, co ..... ~ ] > • "I M2165 60VA OR EQUIVALENT N 240VAC 7 1~2V A .,. vtfJlo8oi :J1<0----."-tl MINIMUM MAXIMUM ADJUST :JI VR1 100k +12V ~ 1k .... . LM324 .,. .,. 100k 14 .,. REVERSE S2 dORWARO RUN ~A;;-HE~ UNIT - - g_ I 50 I I I I I 3 I 7 2200 '+ 25VW 220k .,. + SC9-1-488 .,. .011 , 100k 0.1 +12V TRIANGLE WAVEFORM VT RAIL POWER +17V .,. 47 16VW1 +12V L ________ J I4 I - 120k +9.BV -: ? ? +12V ..,. 0.lI 27k 10k I +12V +12V • +12V ?? EOc VIEWED FROM BELOW B MOTOR BACK EMF -1 .,.. BCE ~ + .,. GNO -~ITT FOLOBACK CONTROL D3 1N4148 \: ~< 01 B0650 .,. +12V 0.l !l 5W MOTOR OVERLOAD BUZZER +11v--+--------. Model Trains & Pulse Power Myths If you read model railroading magazines or talk to some model railroaders, "pulse power" has a bad reputation. There are claims that pulse power makes motors run hot ·and can lead to motors overheating and burning out. As with most myths, there is some technical basis for this belief but further investigation shows that it is not right. In permanent magnet motors, torque is proportional to the average current while the heat dissipated in the motor is proportional to the RMS value of the current. Based on this, the heat produced for a given speed setting will be higher for a pulse waveform than for pure DC. But, as we have already noted, most commercial train controllers hand-held walkaround throttle is unplugged. Back-EMF monitoring As already noted, the pulse voltage from IC2a is fed via logic circuits IC3 and IC4 to the H-pack output stage but let's ignore them for the moment. Instead, let's flick down to the back-EMF monitoring circuit provided by diodes D4, D5 and transistor QB. There is rather more to this part of the circuit than meets the eye. What it does is to monitor the voltage across the motor when the output circuit itself is providing no power. In other words, the speed monitoring circuit looks at the motor in between each pulse delivered by Darlington transistor Ql or Q2. How does it do it? Well, remember that for the forward motor direction Q4 is. continuously on while Q3 is off. This means that virtually the full voltage appearing across the motor appears at the collector of Q3. So the motor voltage is fed via D4 and a 2.2k0 resistor to the non-inverting input of IC2b (over on the lefthand side of the circuit). But D4 feeds the voltage down the 2.2k0 resistor all the time so it gets the pulse voltage as well as the motor back-EMF which is not what 38 SILI CO N Cllll' use pulse power of some sort. Very few use pure DC . In practice then , the difference in motor dissipation between unfiltered DC controllers and the Railpower design is small. The big danger of motors burning out is if the motor stalls due to a binding gear system. Under these conditions , you run the risk of burning out the motor if you apply full track voltage for more than a few seconds . Note that this applies to any model train controller, not just the Railpower. The risk is higher for motors in the smaller gauges such as N or Z-gauge . Pulse power is also reputed to cause motors to be noisier than with pure DC. This tends to be true partly because a controller such as the Railpower allows the loco to run at much lower speeds than would be possible with filtered or unfiltered DC across the track. At these much lower speeds, motor noise becomes much more significant; at higher speeds motor noise is drowned out by gear noise and wheel/rail noises . Noise is also dependent to some extent on the quality of the gear trains and can be amplified by locos of brass construction. It is · sometimes possible to adjust the , loco gear trains to minimise noise . With the majority of locos we have tested, the pulse frequency of 200Hz has been found to be close to optimum. The pulse frequency can be reduced by increasing the .01 µF capacitor at pin 6 or IC1 d. To halve the frequency , double the capacitor's value. we want. So every time a pulse is delivered by Q 1, the pulse waveform Vp also turns on QB. So the pulse voltage never gets to the input of IC2b. Pretty cunning that! Similarly, for the reverse direction, Q3 is always on and the full motor voltage appears at the collector of Q4 and is fed via D5 to the 2.2k0 resistor and thence to the input of ICZb. Again, whenever pulse voltage is present across the motor, QB is turned on, to shunt it to ground. So the voltage fed to IC2b truly represents the motor backEMF and therefore is an indication of the motor's speed. It is a train of pulses, because of the switching action of QB. Absolute pulse-power in the palm of your hand. The controls are speed, forward/reverse and run/stop with (adjustable) simulated inertia . Speed regulation IC2b is a non-inverting amplifier with a gain of 3.2, as set by its 220k0 and lOOkO feedback resistors. Its output is a pulse waveform which is filtered by a 22k0 resistor and 2.2µF capacitor. The smoothed DC voltage, representing the motor's actual speed, is fed to the reference input of ICld, the triangle waveform generator. This has the effect of raising the overall voltage level of the triangle waveform Vt, while its amplitude and frequency remain the same. So what happens if the back-EMF generated by the motor for a certain speed suddenly drops? The effect is to lower the overall voltage level of Vt, the triangle waveform. As can be seen from Fig.3, if Vt is lowered in level with respect to Vs, the pulses delivered by IC2a will be longer and so the power delivered to the motor will be increased and the desired speed will be restored. Overload protection Two op amps, IC2c and IC2d, pro- TO HAND HELD UNIT 0 12VAC INPUT BUZZER + LED2 Fig.6: parts placement diagram for the PCB. Be sure to use the correct part at each location and note that IC2 is oriented differently to the other ICs. VR1 and VR2 set the maximum and minimum track voltages. FROM MAIN BOARD Fig.7: this is the wiring diagram for the hand-held controller. The numbers on the leads correspond to the numbers on the terminal block at the top of Fig.6. VR4 and VR5 set the running and braking inertia. vide the short circuit protection and both of these are wired as comparators. The current passing through the motor is monitored by the o. rn 5W resistor connected to the commoned emitters of Q3 and Q4. The voltage developed across the resistor is fed via a 10k0 resistor to the inverting input, pin 2, of IC2c. The voltage at pin 2 is then compared with a reference voltage at pin 3, which is approximately 0.6 volts. Normally, the voltage at pin 2 will be well below 0.6 volts and so the output of IC2c will remain high, as will the output of IC2d. Therefore, operation of the controller continues as normal. When an excessive current flows through the controller output, a large peak voltage will be developed across the 0. rn sensing resistor and the voltage at pin 2 will rise above the threshold of comparator IC2c. This will cause the output to go low which then pulls pin 12 of IC2a low, via diode DZ. This has the effect of reducing the width of the output pulses and so the fault current is reduced. IC2c also turns on the overload LED to indicate the fault condition. IC2c's action in reducing the fault current tends to cause a "hunt" condition whereby as the current is reduced, the voltage at pin 2 reduces and so the controller again delivers the full pulse width. This causes the current to increase again and IC2c again switches on. This " oscillation" is slowed to some extent by the 0.1µ,F filter capacitor at pin 2 of IC2c, so that the action of IC2c is adequate to cope with short-term overloads and short circuits which may occur when a loco is crossing points. For longer term short circuits though, IC2d comes into play. This op amp monitors the output of IC2c via LED 2 (the overload indicator). When a long duration short circuit occurs, the capacitor at pin 5 is discharged so that its voltage is below the reference voltage at pin 6. This causes IC2d's output to go low which then also pulls pin 2 of IC2a low, via diode D3. So IC2c and IC2d together act to reduce the pulse width and thereby control the output current. IC2d thereby provides a "foldback" current limiting action. IC2d also drives Q7 which sounds the buzzer whenever a short circuit, or overload occurs. This very effectively draws your attention to any overloads, whether momentary or otherwise, so that any faults can be corrected. Just a small point of explanation here: the reference voltage at pin 3 of IC2c is 0.6V which may lead you to conclude that current limiting will occur for currents in excess of A PHIL 1988 39 IC2a, dpending on the setting of the flipflop. Thus, if Q4 is turned on continuously, pulse signals are fed via IC3a, inverter IC4a and transistor Q5, to turn Ql on and off at 200Hz. Similarly, if Q3 is turned on continuously, for the reverse condition, Vp signals are gated through IC3b, inverter IC4b, and transistor Q6, to turn on Q2 at the 200Hz rate. Power supply This view shows how everything fits together inside the hand-held controller unit. The 6-way cable must be securely anchored to prevent lead breakage. 6 amps peak (ie, 0.6V across the 0.10 sensing resistor). In practice though, the 0.lµF filter capacitor at pin 2 allows higher peak currents to pass before limiting occurs. Output Darlington transistors Ql to Q4 are fitted with small heatsinks which normally stay quite cool. If a short circuit is maintained across the track for any length of time though, the transistors will rapidly become very hot. They can withstand this condition for several minutes although the overload buzzer will be sounding stridently and the short should be corrected as soon as possible. Logic circuitry Now we come to the part of the circuit which looks quite tricky but isn't; if you have stuck with the description as far as this point you will have no trouble with the logic. IC3c and IC3d are the key to it all; they are coupled together as an RS flipflop which is controlled by the forward/reverse switch S2. When S2 is set to the forward condition it pulls pin 5 low (normally held high by a 10k0 resistor). This causes the output at pin 4 to go high while the output at pin 3 goes low. The flipflop will then remain in this condition until S2 is switched 40 S!U CON CIIII' The run and stop inertia adjustment pots (VR4 and VR5) are mounted on a small piece of Veroboard (see Fig.7). over to the reverse condition. When that occurs, pin 1 will be pulled low and the flipflop will change state. Pin 3 will now be high and pin 4 will be low. (If you want to better understand this type of flipflop, have a look at our series on Digital Electronics, in the February 1988 issue). The flipflop determines which output transistor remains on continuously; ie, Q3 or Q4. For the forward setting of S2 , pin 4 of IC3c will be high and pin 3 will be low. As a consequence, the output of inverters IC4c and IC4d will be low and Q3 will be off; the output of inverters IC4e and IC4f will be high and so Q4 will be on. IC3a and IC3b gate through the pulse waveform (Vp) signals from The power transformer is a 60V A multitap unit available from Jaycar (Cat. No. MM-2005) or Altronics (Cat. No. M-2165). It is connected to provide a 12V AC output which feeds a bridge rectifier and two 2200µF 25VW electrolytic capacitors. This produces smoothed but unregulated DC of about 17-18V. This is fed to the output stage (Q1-Q4) and to a 3-terminal regulator to produce a regulated + 12V supply which is fed to all the op amps and logic circuits. Methods of construction The Railpower controller can be built in several ways. Many modelling enthusiasts will prefer to build it into their main control console and thus will bury the printed circuit board under the layout. Others will want a self-contained unit with or without the walkaround throttle feature. Still others will want a bare-bones unit without a case but with the walk-around throttle. We have catered for all these possibilities. Only one printed circuit board is required, measuring 117 x 125mm (code SC9-1-488). This accommodates all components except for those in the handheld walk-around throttle. The board has a six-way insulated terminal block for connections to the handheld throttle and two eight-way connectors for the remainder of the connections. For those who want to get started, Fig.6 shows the parts layout on the PCB while Fig.7 shows the wiring details for the hand-held controller. Next month we will give full details of the construction of the Railpower controller in a number of versions. Kits for the project will be available shortly from Jaycar Electronics. ~ ... ), Don't forget to call "Wood for Chips" 4271676 or Fax 428 5198 ~ Six Pages •• •• •• • 1 ~ •• • •• •• •• • • Displays p4 Comparators p3 Transistors p5,6 Ledsp4 Data Books p3 Regulators/Refs p6 Bridgesp4 Special Function p5 Interface p4 Rectifiers p4 Microprocessors p5 • Amplifiers p3 Diodesp4 Memoryp4 • AnalogSwitches p3 Radio& TV p3 Optocouplers p4 • Zenersp4 Temp Sensors p5 Telecomp5 Clocksp3 CMQS - §llllll SEBIES 4000CN 4001BCN 4001CN 4002BCN 4006BCN 4006CN · 4007CN 4008BCN 4009CN 4010CN 4011BCN 4012BCN 4013BCN 4014BCN 4015BCN 4015CN 4016BCN 4017BCN 4018BCN 4019BCN 4020BCN 4022BCN 4023BCN 4024BCN 4024P 4025BCN 4026BCN 4027BCN 4028BCN 4029BCN 4030BCN 4031BCN 4034BCN 4035BCN 4040BCN 4041BCN 4042BCN 4043BCN 4043CN 4044BCN 4044CN 4046BCN 4047BCN 4048BCN 4049CN 4050BCN 4051BCN 4052BCN 4053BCN 4060BCN 4066BCN 4068BCN 4069BCN 4070BCN 4071BCN 4072BCN 4073BCN 4075BCN 4076BCN 4077BCN 4081BCN 4082BCN 4085BCN 4089BCN 4093BCN 4094BCN 4099BCN 4501BCN 4502BCN 4503BCN 4504UBN DUAL 3 INP NOR QUAD 2 INP NOR QUAD 2 INP NOR DUAL 4 INP NOR 18 STAGE STATIC REG 18 BIT STATIC SIR DUAL COMP PAIR +INV 4 BIT FULL ADDER HEX BUFFER INVERTER HEX BUFFER NON INV QUAD 2 INP NANO DUAL 4 INP NANO DUAL D FLIP FLOP 8 BIT STATIC S/R DUAL 4 BIT STAT S/R DUAL 5 BIT REGISTER SEE 4066BCN DECADE CTR/DIV PRESET DIV BY N DUAL AND OR SELECT 14 STAGE R/C BINARY OIV BY 8 CTR/DVR TRIPLE 3 INP NANO 7 BIT BINARY CTR DUAL V.C. MULTIVIS TRIPLE 3 INP NOR DECADE CTR/DVR DUAL J-K FLIP FLOP BCD DECIMAL DCDR PRESET UP/DOWN CTR 4070/74C86 PREFERRED 64 BIT STATIC S/R 8 BIT STATIC S/R 4 BIT SHIFT REGISTER 12 BIT BINARY R/C CTR QUAD TRUE/COMP BUFF QUADDLATCH QUAD NOR LATCH QUAD NOR R-S LATCH QUAD NANO LATCH QUAD NANO R-S LATCH PHASE LOCKED LOOP MONOSTABLE EXP 8 INP GATE HEX BUFFER INVERTING HEX BUFFER NON INVER 8 CHANNEL MUX DIFF 4 CHANNEL MUX TRIPLE 2 CHANNEL MUX 14 BIT CTR/OSC QUAD BILATERAL SWTCH 8 INP NANO SEE 74C04N SEE 74C86N QUAD2 INPOR DUAL4 INP OR TRIPLE 3 INP AND TRIPLE 3 INP OR SEE 74C173N QUAD EXCLUSIVE NOR · QUAD 2 INP AND DUAL 4 INP AND DUAL AND/OR/INVERT BINARY RATE MULTIP QUAD 2 NANO SCHMIH 8 STAGE STORAGE REG 8 BIT ADDRESS LATCH DUAL 4 INP NANO STROBED HEX INVERTER SEE MM80C97N TTUCMOS TRANSLATOR 0.75 0.45 0.50 0.60 1.70 1.20 0.45 1.70 0.90 0.90 0.45 0.45 0.70 1.45 1.40 0.70 0.70 1.30 1.50 0.80 1.60 1.45 1.45 1.30 6.20 0.40 0.95 0.95 1.15 1.40 1.40 2.95 3.10 1.80 1.10 1.50 1.50 1.20 1.10 1.25 1.00 1.85 1.90 1.20 0.60 0.50 1.20 1.20 1.20 1.10 0.80 0.50 0.45 0.50 0.50 0.40 0.45 0.45 0.45 1.90 5.25 0.75 3.30 1.90 1.50 1.30 1.50 4506BCN DUAL AND/OR/INVERT 4507BCN 4507AN DUAL 4 BIT LATCH 4508BCN BCD UP/DOWN CTR 4510BCN BCD/7 SEGMENT DCDR 4511BCN 8 CHANNEL DATA SLCTR 4512BCN BCD/7 SEGMENT OVA 4513BCN 4 BIT LATCH 4/16 DCDR 4514BCN 4 BIT LATCH 4/16 DCDR 4515BCN 4516BCN BINARY UP/DOWN CTR DUAL BCD UP CTR 4518BCN 4520BCN DUAL BINARY UP CTR 4521BCN 24 STAGE DIVIDER 4522BCN DIVIDE BY N(BCD) 4526BCN DIVIDE BY N(BINARY) 4527BCN BCD RATE MULTIPLIER 4528BCN DUAL MONOSTABLE 4529BCN · DUAL 4 CHANNEL AN/SW 4532BCN 8 BIT PRIORITY ENCDR 4538BCN DUAL MONOSTABLE PROGRAMMABLE TIMER 4541BCN BCD/7 SEGMENT DCDR 4543BCN 3 DIGIT BCD CTR 4553BCN 4555BCN DUAL 1/4 MUX DUAL 1/4MUX 4556BCN DUAL BCD/BINARY CTR 4569BCN HEX GATE 4572BCN DUAL SCHMITT TRIGGER 4583BCN 4584BCN SEE 74C14N 4585BCN SEE 74C85N DUAL 4 BIT LATCH 4723BCN 8 BIT ADDRESS LATCH 4724BCN 14555BCN DUAL 1/4 DECODER 40106BCN SEE 74C14N 40160BCN SEE 74C160N 40161BCN SEE 74C161N 40162BCN SEE 74C162N 40163BCN SEE 74C163N 40174BCN SEE 74C174N 40175BCN SEE 74C175N 40192BCN SEE 74C192N 40193BCN SEE 74C193N 40195BCN SEE 74C195N MC14161BCN SEE 74C161N MC14174BCN SEE 74C174N MC14175BCN SEE 74C175N 0.95 0.85 0.85 2.65 1.40 1.60 1.40 2.50 3.50 2.90 1.60 1.50 1.50 1.90 1.90 1.90 1.90 1.90 2.40 3.45 1.95 1.40 2.20 3.10 3.30 1.50 2.10 1.60 0.90 3.40 3.40 0.80 CMQS • Z~ SEBIES 74C00N 74C02N 74C04N 74C08N 74C10N 74C14N 74C20N 74C30N 74C32N 74C42N 74C48N 74C73N 74C74N 74C76N 74C83N 74C85N 74C86N 74C89N 74C90N 74C93N 74C95N 74C107N 74C150N QUAD 2 INP NANO QUAD 2 INP NOR HEX INVERTER QUAD 2 INP AND TRIPLE 3 INP NANO HEX SCHMITT TRIGGER DUAL 4 INP NANO 8 INPNAND QUAD2 INPOR BCD/DECIMAL DCDR BCD/7 SEGMENT DCDR DUAL.J-K FLIP FLOP DUAL D FLIP FLOP DUAL J-K FLIP FLOP BINARY FULL ADDER 4 BIT COMPARATOR QUAD EXCLUSIVE OR 16X4RAM DECADE CTR BINARYCTR 4 BIT SHIFT RGSTR DUAL J-K FLIP FLOP 1 OF 16 DECODER 0.90 0.90 0,50 0.90 0,90 1.50 0.90 0.90 0,90 2.50 3.80 1.70 2.25 2.25 3.50 3.70 0.50 13.80 2.70 2.65 2.90 2.90 8.50 74C151N 74C157N 74C160N 74C161N 74C162N 74C163N 74C164N 74C165N 74C173N 74C174N 74C175N 74C192N 74C193N 74C195N 74C221N 74C240N 74C244N 74C373N 74C374N 74C901N 74C902N 74C903N 74C904N 74C905N 74C906N 74C907N 74C908N 74C909N 74C911N 74C912N 74C914N 74C915N 74C917N 74C918N 74C920D 74C921D 74C922N 74C923N 74C925N 74C926N 74C927N 74C928N 74C932N 74C941N 74C946N 74C956N 80C95N MM80C96N MM80C97N MM80C98N 74ALS, 74AS, 74F, 74LS, 745, p2 & 3 4000 ,74C, 74HC, 74HCT CMOS p1 & 2 A to D & D to A p3 Crystals p3 SCR's & Triacs p5 8/ 1 MUX 5.90 5.90 QUAD 2/1 MUX PRESET DECADE CTR 2.60 PRESET BINARY CTR 2.60 PRESET DECADE CTR 2.60 2.60 PRESET BINARY CTR 3.40 8 BIT SI PO SIR 3.40 8 BIT PI SO S/R 3.40 TRI STATE QUAD LATCH 2.20 HEX D FLIP FLOP QUAD D FLIP FLOP 2.20 UP/DOWN DECADE CTR 2.80 2.80 UP/DOWN BINARY CTR 4 BIT PARALLEL S/ R 2.20 . 3.70 DUAL MONOSTABLE TRI STATE OCTAL BUF 3.70 3.70 TRI STATE OCTAL BUF TRI STATE OCTAL LATCH 5.15 TRI STATE OCTAL D FI 5.15 INVERT BUFFER 2.00 HEX BUFFER 2.00 HEX INVERT BUFFER 2.00 HEX BUFFER 2.00 12 BIT SAR 19.65 HEX N CHAN BUFFER 2.00 HEX P CHAN BUFFER 2.00 DUAL HI VOLT DRIVER 3.60 CMOS COMP QUAD COMP 4.85 DISPLAY CONTROLLER 19.40 DISPLAY CONTROLLER 19.40 HEX SCHMITT TRIGGER 3.80 7 SEGMENT/BCD DCDR 3.50 DISPLAY CONTROLLER 19.40 DUAL HI VOLT DRIVER 3.45 17,70 256 X 4 RAM 250 NS 17,70 256 X 4 RAM 250 NS 9.90 16 KEY ENCODER 9.95 20 KEY ENCODER 13.20 401GITCTR 13.20 4 DIGITCTR 13.20 4DIGITCTR 13.20 4 DIGIT CTR 3.80 PHASE DETECTOR 4,00 TRI STATE OCTAL BUF 4 DIGIT 17 SEG CTR 20.10 4 DIGIT 17 SEG CTR 20.10 TRI STATE HEX BUF 1.40 TRI STATE HEX INVTR 1.40 TRI STATE HEX BUFFER 0.75 1.40 TRI STATE HEX INVTR CMQS - Z!lllC SEBIES 74HC00N 74HC02N 74HC03N 74HC04N 74HCU04N 74HC08N 74HC10N 74HC11N 74HC14N 74HC20N 74HC21N 74HC27N 74HC30N 74HC32N 74HC51N 74HC73N 74HC74AN 74HC75N 74HC76N 74HC85N QUAD 2 INP NANO QUAD 2 INP NOR QUAD 2 INP NANO HEX INVERTER HEX INVERTER QUAD 2 INP AND TRIPLE 3 INP NANO TRIPLE 3 INP AND HEX SCHMITT TRIGGER DUAL 4 INP NANO DUAL 4 INP AND TRIPLE 3 INP NOR 8 INP NANO QUAD2 1NPOR DUAL AND/OR/ INVERT DUAL J-K FLIP FLOP DUAL D FLIP FLOP QUAD D FLIP FLOP DUAL J-K FLIP FLOP 4 BIT COMPARATOR • • e •• 0.70 0.70 0,90 0.70 0.95 0.70 0,70 0.70 1. 50 0.70 0.90 0.70 0.70 0.70 0.90 1.00 1.00 1.25 1.10 1.40 74HC86N QUAD EXCLUSIVE OR 74HC107N DUAL J-K FLIP FLOP 74HC112N DUAL J-K FLIP FLOP 74HC113N DUAL J-K FLIP FLOP 74HC123AN DUAL MONOSTABLE 74HC125N TRI-STATE BUFFER 74HC126N TRI-STATE BUFFER 74HC132N QUAD 2 INP SCHMIH 74HC133N 13 INP NANO 74HC137N 3 TO 8 DCDR/LATCH 74HC138N 3/8 DECODER 74HC139N DUAL 2/4 DECODER 74HC147N 10/4 ENCODER 74HC151N 8/ 1 MUX 74HC153N DUAL4/ 1 MUX 74HC154N 4/ 16 DECODER 74HC157N QUAD2MU X 74HC158N QUAD2 MU X 74HC160N PRESET DECADE CTR 74HC161N PRESET BINARY CTR 74HC163N BINARYCTR 74HC164N 8 BIT SI PO S/R 74HC165N 8 BIT PI SO SIR 74HC173N QUAD D FLIP FLOP 74HC174N HEX D FLIP FLOP 74HC175N . QUAD D FLIP FLOP 74HC192N UP/DOWN DECADE 74HC193N UP/DOWN BINARY 74HC194N SHIFT REGISTER 74HC195N SHIFT REGISTER 74HC221AN DUAL MONOSTABLE 74HC240N OCTAL BUFFER 74HC241N OCTAL BUFFER 74HC242N TRI-STATE TRCVR 74HC243N TRI-STATE TRCVR 74HC244N OCTAL BUFFER 74HC245AN TRI-STATE OCTAL TCVR 74HC251N TRI-STATE 2/1 MUX 74HC253N DUAL4/ 1 MUX 74HC257N QUAD2MUX 74HC259N 8 BIT ADDRESS LATCH 74HC266N QUAD 2 INP EX OR 74HC273N OCTAL D FLIP FLOP 74HC280N 9 BIT PARITY GENER 74HC299N TRI-STATE 8 BIT S/R 74HC354N LATCHEDMUX 74HC356N TRI-STATE HEX BUFFER 74HC365N TRI-STATE HEX BUFFER 74HC366N TRI-STATE HEX BUFFER 74HC367N TRI-STATE HEX BUFFER 74HC368N TRI-STATE HEX BUFFER 74HC373N OCTAL D LATCH 74HC374N OCTAL D FLIP FLOP 74HC390N DUAL DECADE CTR 74HC393N DUAL BINARY CTR 74HC423AN DUAL MONOSTABLE 74HC521N SEE 74HC688N 74HC533N OCTAL D LATCH 74HC534N OCTAL D FLIP FLOP 74HC540N TRI-STATE OCTAL BUF 74HC541N TRI -STATE OCTAL BUF 74HC563N TRI-STATE OCTAL DVR 74HC573N TRI-STATE OCTAL DVR 74HC574N TRI -STATE OCTAL OVA 74HC640N TRI-STATE OCTAL TCVR 74HC643N TRI -STATE OCTAL TCVR 74HC688N 8 BIT COMPARATOR 74HC4002N DUAL 4 INP NOR 74HC4020N BINARY CTR 74HC4040N BINARY CTR 74HC4046N PHASE LOCK LOOP 74HC4049N HEX BUFFER 74HC4050N HEX BUFFER 0.90 1.80 1.80 1.80 1.60 1.40 1.40 1.95 0.85 2.10 1.40 1.40 2.30 1.20 1.20 4.40 1.20 1.20 2.10 2.10 2.10 2.25 2.25 2.00 1.35 1.35 2.15 2.15 2.15 2.15 3.20 3.05 3.05 3.05. 3.05 2.1Q 3.05 1.20 1.75 1.20 2.90 1.75 2.6.0 5.45 6.35 2.40 2.40 1.80 1.80 1.80 1.80 2.80 2.80 2.75 2.75 4.00 3.25 3.25 2.55 2.70 4,25 1.90 1.90 4.00 3.75 3.50 1.00 2.45 2.50 2.60 1.65 1.65 Tax Exempt Prices upon presentation of valid tax exemption certificate - min value $10.00 per line item. Wholesale prices on request. Credit only to established accounts. Cheque, Money Order or Credit Cards with all other orders please. More Products being added daily - such as FACT and AC ranges. Inclusion in listing does NOT guarantee availability. Please check to avoid disappointment 2 Don't forget to call 74HC4052N 74HC4053N 74HC4060N 74HC4066N 74HC4075N 74HC4078N 74HC4316N 74HC4538N DUAL 4 CHANNEL MUX TRIPLE 2 CHAN MUX BINARY CTA QUAD BILATERAL SWTCH TRIPLE INP OR 8 INP NOR QUAD ANALOG SWTCH DUAL MONOSTABLE 2.40 2.40 2.65 1.75 1.00 0.80 3.35 1.90 ~MQS • Z!lll~I SliBlliS 74HCT00N QUAD 2 INP NANO 74HCT04N HEX INVERTER 74HCT138N 3/8 DECODER 74HCT240N LS CMPTBL OCTAL BUF 74HCT241N TRI STATE OCTAL OVA 74HCT244N TRI STATE OCTAL OVA 74HCT245N TRI STATE OCTAL TCVR 74HCT373N TRI STATE OCTAL LATCH 74HCT374N TAI STATE OCTAL LATCH 0.95 0.95 1.60 4.80 4.80 4.80 3.20 3.70 3.70 ffi·NUBIH 5401J 5408J 7400N 7401N 7402N 0.90 7404N 7405N 7406N 7407N 7409N 7410N 7411N 7412N 7413N 7414N 7416N 7417N 7420N 7421N 7423N 7425N 7426N 7427N 7430N 7432N 7437N 7438N 7440N 7441AN 7442N 7445N 7446AN 7447N 7450N 7451N 7453N 7454N 7460N 7470N 7473N 7475N 7476N 7482N 7483N 7485N 7486N 7492AN 7493AN 7495J 7495N 7496N 7497N 74100N 74107N 74109N 74121N 74122N 74123N 74125N 74126N 74128N 74132N 74141N 74145N 74147N 74148N 74150N 74151AN 74153N 74155N 74156N 74157N 74160AN 74161AN QUAD 2 INP NANO QUAD 2 INP AND QUAD 2 INP NAND QUAD 2 INP O.C. QUAD 2 INP NOR 1.50 1.50 0.80 0.80 HEX INVERTER HEX INVERTER O.C. HEX INVERTER 30V HEX INVERTER 30V QUAD 2 INP AND O.C. TRIPLE 3 INP NANO TRIPLE 3 INP AND ' TRIPLE 3 INP AND DUAL 4 INP SCHMITT QUAD SCHMITT TRIGGER SEE ALSO 7606N SEE ALSO 7407N DUAL 4 INP NANO DUAL 4 INP AND DUAL 4 INP NOR DUAL 4 INP NOR QUAD 2 INP NANO TRIPLE 2 INP NOR 8 INP NANO QUAD2 INPOA QUAD 2 !NP NANO BUF QUAD 2 NANO BUF O.C. DUAL 4 INP NANO BUFF BCD/DEC DRIVER BCD/DEC DECODER BCD/DEC DRIVER BCD/7 SEGMENT OVA BCD/7 SEGMENT OVA DUAL 2 WIDE AND/OR/INV DUAL 2 WIDE AND/OR/INV AND/OR/INVERT GATE 4 WIDE AND/OR/INVERTER DUAL 4 INP EXPANDER SINGLE J-K FLIP FLOP DUAL J-K FLIP FLOP QUAD LATCH DUAL J-K PRESET/CLEAR 2 BIT BIN FULL ADDER 4 BIT FULL ADDER 4 BIT COMPARATOR QUAD EXCLUSIVE OR DIVIDE BY 12 CTR BINARYCTA 4 BIT PARALLEL RGSTR 4 BIT SIR S/L RGSTR 5 BIT REGISTER MODULO 64 MULTPLIER DUAL QUAD LATCH DUAL J-K FLIP-FLOP DUAL J-K (FSC 9024) ONE SHOT MONOSTABLE MULTIVIB DUAL ONE SHOT TRI-STATE BUFFER TRI-STATE BUFFER QUAD 50 OHM DRIVER QUAD SCHMITT TRIGGER NIXIE DRIVER BCD/DECIMAL DRIVER 10/4 PRIORITY ENCDR 8/3 PRIORITY ENCDR 16/1 MUX 8/1 MUX DUAL4/1 MUX DUAL 2/4 DEMUX DUAL 1/4 MUX QUAD2/1 MUX 4 BIT DECADE CTR 4 BIT BINARY CTA 0.90 1.00 0.95 0.95 1.00 0.85 1.00 0.90 0.95 1.40 1.00 0.90 0.95 0.90 0.95 1.30 1.15 1.15 0.95 0.90 0.95 1.05 0.90 2.20 1.40 1.95 1.55 1.55 0.95 0.95 0.95 0.90 0.90 1.00 1.15 1.20 1.50 2.90 1.50 1.50 1.15 1.20 1.25 1.10 1.20 1.20 3.40 1.90 1.15 1.15 0.95 0.90 1.40 0.95 0.95 1.50 1.05 2.30 1.50 3.55 2.30 1.95 1.20 1.65 1.20 1.30 1.15 1.20 1.25 74162AN 74163AN 74164N 74165N 74166N 74170N 74172N 74173N 74174N 74175N 74176N 74184N 74185AN 74189N 74190N 74191N 74192N 74193N 74194N 74195N 74196N 74198N 74199N 74221N 74279N 74284N 74293N 74365N 74366N 74367N 74368N 74390N 74393N 8601N 8602N DM2502CN DM8093N DM8094N DM8095N DM8096N DM8097N DM8098N DM8099N DM8122N DM8123N DM8130N DM8131N DM8136N DM8160N DM8220N DM8223N DM8288N DM8312N DM8334N DM8520N DM8542N DM8544N DM8552N DM8553N DM8556N DM8578N DM8875N DM9312N DM9334N DM9601N DM9602N ,, ••o 00 for Chips" 4271676 or Fax 428 5198 <at> 4 BIT DECADE CTA 1.25 4 BIT BINARY CTR 1.35 8 BIT SI PO RGSTA 1.35 8 BIT PI/SO RGSTR 1.50 8 BIT PI SO AGSTA 1.95 4 X 4 RGSTR FILE 3.05 16 BIT RGSTR FILE 1.00 QUAD TRI-STATE LATCH 1.85 HEX D FLIP-FLOP 1.45 QUAD D FLIP-FLOP 1.45 DECADECTR 1.95 BCD/BINARY CVTR 5.55 BINARY/BCD CVTR 5.55 TRI-STATE 64 BIT RAM 4.45 UP/DOWN DECADE CTR 1.35 SYNC UP/DOWN BINARY 1.35 UP/DOWN BINARY CTR 1.00 UP/DOWN BINARY CTA 1.25 4 BIT UNIVERSAL RGSTA 1.35 4 BIT UNIVERSAL RGSTR 1.00 4 BIT DECADE CTR 2.00 8 BIT RIGHT/LEFT REG 3.85 8 BIT PARALLEL 1/0 3.85 MONOSTABLE 2.45 QUAD S-R LATCH 2.90 4 X 4 MULTIPLIER 5.75 BINAAYCTR 2.90 TRI-STATE HEX BUFFER 1.45 HEX TAI-STATE BUFFER 1.45 TRI-STATE HEX BUFFER 1.40 TRI-STATE HEX BUFFER 1.45 DUAL DECADE CTR 2.90 DUAL BINARY CTA 3.25 RETRIG MONOSTABLE 1.50 DUAL MONOSTABLE 2.80 8 BIT TTL S.A.A. 13.90 SEE 74125N SEE 74126N SEE 74365N SEE 74366N SEE 74367N SEE 74368N BUFFER 2.90 SEE 74157N TRI STATE 2/1 MUX 3.50 10 BIT COMPARATOR 6.80 6 BIT COMPARATOR 5.65 6 BIT COMPARATOR 5.15 5.15 6 BIT COMPARATOR 9 BIT PARITY GENEAAT 7.00 2.90 8/ 1 DEMUX PRESET DIVIDE BY 12 2.90 8/ 1 MUX 3.10 8 BIT ADDRESS LATCH 8.65 MODULO N DIVIDER 11.70 QUAD 1/0 REGISTER 7.20 QUAD SWTCH DEBOUNCE 2.60 TRI STATE CTR/LATCH 8.25 TRI STATE 8 BIT LATC 9.50 BINAAYCTA 4.05 CHARACTER GENERATOR 0.90 SEE 74284N SEE 8312N SEE 8834N SEE 8601N SEE 8602N Z!IALSSliBlliS QUAD 2 INP NANO 74ALS00N QUAD 2 INP NANO O.C. 74ALS01N QUAD 2 INP NOR 74ALS02N QUAD 2 INP NANO O.C. 74ALS03B 74ALS04A HEX BUFFER 74ALS05N HEX BUFFER QUAD 2 INP AND 74ALS08N 74ALS09N QUAD 2 INP AND 74ALS10N TRIPLE 3 INP NANO 74ALS11N TRIPLE 3 INP AND 74ALS12AN TRIPLE 3 INP NANO 74ALS14N HEX SCHMITT TRIGGER 74ALS15N TRIPLE 3 INP AND 74ALS20N DUAL 4 INP NANO 74ALS21N DUAL 4 INP AND 74ALS22BN DUAL 4 INP NANO O.C. 74ALS27N TRIPLE 3 INP NOR 74ALS30N 8 INP NANO 74ALS32N QUAD2 INPOR 74ALS33N QUAD 2 INP NOA BUFA 74ALS37N QUAD 2 INP NANO BUFA 74ALS38AN QUAD 2 INP NANO BUFA 74ALS40N DUAL 4 INP NAND BUFR 74ALS74N DUAL D FLIP FLOP 74ALS109N DUAL JK FLIP FLOP 74ALS131N 3/8 DECODER W/LATCH 74ALS133N 13 INP NANO 74ALS137N 3/8 DECODER-DEMUX 74ALS138N 3/8 DECODER-DEMUX 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 1.80 0.70 0.70 0.70 0.70 0.70 0.70 0.70 1.10 1.15 1.15 1.10 0.75 0.80 1.90 0.90 1.90 1.30 8 CHANNEL MUX QUAD2/1 MUX QUAD2/1 MUX DECADE CTR DECADE CTR UP/DOWN CTR OCTAL BUFFER OCTAL D FLIP FLOP TAI STATE OCTAL LTCH TAI STATE OCTAL LTCH INVERTING OCTAL L TCH INVERTING OCTAL LTCH SEE 74ALS580AN SEE 74ALS576AN OCTAL D FLIP FLOP OCTAL D FLIP FLOP OCTAL D LATCH BUFFER 74ALS00 BUFFER 74ALS02 BUFFER 74ALS08 BUFFER 74ALS10 BUFFER 74ALS11 BUFFER 74ALS32 1.65 1.95 1.95 1.50 1.50 1.50 2.15 2.35 1.80 1.90 2.55 2.55 QUAD 2 INP NOR QUAD2 INPOR DUAL D FLIP FLOP TRI-STATE OCTAL D 0.70 0.70 0.90 2.90 QUAD 2 INP NANO QUAD 2 INP NOA HEX INVERTER QUAD 2 INP AND TRIPLE 3 INP NANO TRIPLE 3 INP AND 4 WIDE AND/OR/INVTR DUAL D FLIP FLOP QUAD EXCLUSIVE OR DUAL J-K FLIP FLOP 1/8MUX DUAL 1/4MUX 8 BIT SI/SO AGSTR OCTAL TRI-STATE BUFA DUAL 1/4 MUX 8 BIT STORAGE RGSTA ALU/FUNCTION GNATR OCTAL TPANT LATCH OCTAL D FLIP FLOP 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.85 1.10 1.20 1.60 1.60 1.90 2.90 1.80 3.90 2.10 3.90 3.90 QUAD 2 INP NANO SEE 74ALS01N QUAD 2 INP NOR QUAD 2 INP NANO O.C. HEX INVERTER QUAD 2 INP AND QUAD 2 INP AND O.C. TRIPLE 3 INP NAND TRIPLE 3 INP AND TRIPLE 3 INP NANO DUAL 4 INP SCHMITT HEX SCHMITT TRIGGER TRIPLE 3 INP AND DUAL 4 INP NANO DUAL 4 INP AND DUAL 4 INP NANO QUAD 2 INP NANO HV TRIPLE 3 INP NOA QUAD 2 INP NOR 8 INP NANO DELAY ELEMENT QUAD2 INPOA QUAD 2 INP NOR QUAD 2 INP NANO BUFA QUAD 2 INP NANO BUFR DUAL 4 INP NANO BUFR BCD/DECIMAL DCDR BCD/7 SEGMENT OVA BCD/7 SEGMENT OVA BCD/7 SEGMENT OVA QUAD 2 INP AND/OR/IN 2 INP AND/OR/IN AND/OR/INVERT GATE DUAL J-K FLIP-FLOP DUAL J-K FLIP-FLOP QUAD LATCH DUAL J-K FLIP FLOP DUAL J-K FLIP FLOP 4 BIT FULL ADDER 4 BIT COMPARATOR QUAD EXCLUSIVE OR DECADE CTR DIVIDE BY 12 CTA 0.70 0.55 0.55 0.55 0.65 0.55 0.75 0.55 0.75 0.75 0.85 0.75 0.75 0.75 0.75 0.75 0.85 0.85 0.85 0.60 0.60 0.60 0.60 0.60 0.75 0.70 0.80 1.50 1.70 1.70 0.70 0.80 0.60 0.55 0.90 0.90 0.90 1.00 1.10 0.85 0.55 1.10 1.10 74ALS151N 74ALS157N 74ALS158N 74ALS160N 74ALS162BN 74ALS169BN 74ALS244N 74ALS273N 74ALS373N 74ALS374N 74ALS533N 74ALS534N 74ALS563N 74ALS564N 74ALS574N 74ALS576N 74ALS580N 74ALS1000N 74ALS1002N 74ALS1008N 74ALS1010N 74ALS1011 N 74ALS1032N 2.25 2.55 3.75 1.10 1.10 1.10 1.10 1.10 1.10 Z4ASSliBlliS 74AS02N 74AS32N 74AS74N 74AS374N Z!IESliBlliS 74F00N 74F02N 74F04N 74F08N 74F10N 74F11N 74F64N 74F74N 74F86N 74F109N 74F151N 74F153N 74F164N 74F244N 74F253N 74F323N 74F381N 74F533N 74F534N Z!ILS SliBlliS 74LS00N 74LS01N 74LS02N 74LS03N 74LS04N 74LS08N 74LS09N 74LS10N 74LS11N 74LS12N 74LS13N 74LS14N 74LS15N 74LS20N 74LS21N 74LS22N 74LS26N 74LS27N 74LS28N 74LS30N 74LS31N 74LS32N 74LS33N 74LS37N .74LS38N 74LS40N 74LS42N 74LS47N 74LS48N 74LS49N 74LS51N 74LS54N 74LS55N 74LS73AN 74LS74AN 74LS75N 74LS76AN 74LS78N 74LS83AN 74LS85N 74LS86N 74LS90N 74LS92N 74LS93AN BINARYCTR 1.10 74LS95N 4 BIT PARALLEL AGSTA 1.10 74LS107AN DUAL J-K FLIP-FLOP 0.85 74LS109AN DUAL J-K FLIP-FLOP 0.85 74LS112AN DUAL J-K FLIP-FLOP 0.65 74LS113AN DUAL J-K EDGE TRIGGER 0.65 74LS114AN DUAL J-K NEGATIVE 0.75 74LS122N RETRIG. MONOSTABLE 1.20 74LS123N DUAL RETAIG. MONO 1.20 74LS125AN TRI STATE QUAD BUFR 0.95 74LS126AN TRI STATE QUAD BUFR 0.95 74LS132N QUAD SCHMITT TRIGGER 0.95 74LS133N 13 INP NANO 0.90 74LS138N EXPAND 3/8 DECODER 1.15 74LS139N DUAL 2/4 DECODER 1.15 74LS145N 1/10 DECODER/OVA 1.45 74LS147N 10/4 PRIORITY ENCDR 1.90 74LS148N 8/3 PRIORITY ENCDR 2.80 74LS151N 8/1 MUX 1.20 74LS153N DUAL4/1 MUX 0.95 74LS154N 4/16 DECODER 3.20 74LS155N DUAL 2/4 DEMUX 1.40 74LS156N DUAL 2/4 DEMUX 1.45 74LS157N QUAD 2/1 MUX 1.10 74LS158N QUAD 2/1 MUX INVTR 0.95 74LS160AN SYNCH DECADE CTR 1.20 74LS161AN PRESET BINARY CTR 1.20 74LS162AN SYNCH DECADE CTA 1.20 74LS163AN PAESET BINARY CTR 1.20 74LS164N 8 BIT SHIFT RGSTR 1.30 74LS165N 8 BIT SHIFT AGSTA 1.10 74LS166N 8 BIT SHIFT RGSTR 2.40 74LS169AN UP/DOWN BINARY CTA 2.85 74LS170N 4 X 4 REGISTER FILE 1.00 74LS173AN TRI STATE QUAD D F/F 1.10 74LS174N HEX D FLIP-FLOP 1.10 74LS175N QUAD D FLIP-FLOP 0.90 74LS190N UP/DOWN DECADE CTR 1.40 74LS191N UP/DOWN BINARY CTR 1.10 74LS192N UP/DOWN DECADE CTR 1.10 74LS193N UP/DOWN BINARY CTA 1.10 74LS194AN 4 BIT UNIVERSAL SIR 1.10 74LS195AN 4 BIT PARALLEL SIA 0.95 74LS196N DECADECTA 1.10 74LS197N BINARYCTR 1.20 74LS221N DUAL MONOSTABLE 1.95 74LS240N TRI STATE OCTAL BUFA 2.30 74LS241N TRI STATE OCTAL BUFR 2.30 74LS242N SEE 74ALS242N 2.30 74LS243N TRI STATE QUAD TCVR 2.00 74LS244N TAI STATE OCTAL BUFA 2.30 74LS245N TAI STATE OCTAL BUFA 2.30 74LS247N BCD/7 SEGMENT OVA 1.40 74LS248N BCD/7 SEGMENT OVA 1.35 74LS249N BCD/7 SEGMENT OVA 1.40 74LS251N TAI STATE 2/1 MUX 1.40 74LS253N TRI STATE 4/1 MUX 1.25 74LS256N DUAL 4 BIT ADAS LTCH 1.60 74LS257BN QUAD 2/1 MUX 1.10 74LS258BN QUAD 2/1 MUX _ 1.10 74LS259N 8 BIT ADAS LTCH 2.15 74LS261 N 2 X 4 BINARY MULTIP 1.90 74LS266N QUAD 2 INP EX NOR 0.80 74LS273N 1.90 OCTAL D FLIP FLOP 74LS279N QUAD SET/RESET LATCH 0.60 74LS280N 1.90 9 BIT PARITY GENER 74LS283N 4 BIT FULL ADDER 1.10 74LS290N DECADECTR 1.30 74LS293N 1.00 BINAAYCTA 74LS295N 1.60 4 BIT REGISTER 74LS298N QUAD 2 PORT REGISTER 1.50 74LS299N 8 BIT UNIVERSAL RGSTR 2.90 74LS323N 8 BIT UNIVERSAL RGSTA 4.20 74LS353N 2.00 DUAL 1/4 MUX 0.90 74LS365AN TRI STATE HEX BUFR 74LS366AN TRI STATE HEX INVTR 0.90 0.90 74LS367AN TRI STATE HEX BUFR 74LS368AN TAI STATE HEX INVTR 0.90 1.90 74LS373N TRI STATE OCTAL D 1.90 74LS374N TAI STATE OCTAL D 74LS375N 0.90 4 BIT LATCH 2.05 74LS377N OCTAL D LATCH 74LS386N QUAD 2 INP EX OR 0.90 TRI STATE DUAL CTR 1.75 74LS390N TRI STATE DUAL CTR 1.70 74LS393N OCTAL BUFFER 2.50 74LS540N OCTAL BUFFER 2.50 74LS541N 8 BIT BINARY CTR 74LS590N 11.05 8 BIT BINARY CTR 11.05 74LS592N VOLTAGE CNTRL OSC. 74LS628N 3.90 VOLTAGE CNTRL OSC. 5.85 74LS629N OCTAL TRI-STATE TCVA 3.80 74LS640N 74LS645N TRI-STATE OCTAL BUFR 2.65 TRI STATE 4X4 REG 10 74LS670N 2.60 8 BIT COMPARATOR 74LS688N 3.25 74LS952N 8 BIT DUAL RANK SIA 5.35 DM81LS95AN TAI ST OCTAL BUFR 3.70 DM81 LS97AN TRI ST OCTAL BUFR 3.70 Tax Exempt Prices upon presentation of valid tax exemption certificate_- min value $10.00 per line item . Wholesale prices on request. Credit only to established accounts. Cheque, Money Order or Credit Cards with all other orders please. More Products being added daily - such as FACT and AC ranges . Inclusion In listing does NOT guarantee availabilitf. Please check to avoid disappointment ~~) Don't forget to call "Wood for Chips" 427 1676 or Fax 428 5198 3 '";1 ADC1210HCD 12 BIT ND 94.90 12 BIT BCD OUT 20.95 ADC3511CC ADD3501C 31/2 DIGIT DVM 20.15 ADD3701 CCN 3 3/4 DIGIT DVM 23.65 DAC0800LCN 8 BIT D/A 0.19% 3.50 Z4SS!;BIES 2.90 DAC0808LC 8BITD/A0.19% DAC0830LCN 8 BIT MP COMP 0.05% 11.15 74S00N QUAD 2 INP NANO 0.90 DAC0831 LCN 8 BIT MP COMP 0.10% 9.90 74S02N SEE 74AS02N 0.90 18.35 QUAD 2 INP NANO O.C. 0.90 DAC1 000LCN 10 BIT MP COM 0.05% 74S03N 18.35 74S04N HEX INVERTER 0.90 DAC1006LCN 10 BIT MP COM 0.05% 19.50 HEX INVERTER O.C. 1.25 DAC1020LCN 10 BIT 0 /A 0.05% 74S05N QUAD 2 INP NANO 0.90 DAC1 203HCD D TO A 261.00 74S08N 19.00 74S10N TRIPLE 3 INP NANO 0.90 DAC1220LCN 12 BIT DIA 0.05% 14.75 74S11N SEE 74AS11N 1.00 DAC1 221LCN 12 BIT DIA 0.10% 1.40 DAC1 222LCN 12 BIT D/A 0.20% 12.10 74S15N TRIPLE 3 INP AND DAC1230LC 8-BIT UP COMP DIA 30.15 74S20N DUAL 4 INP NANO 0.90 74S22N DAC1208LCD-1 DAC1208J 0-70C 23.50 DUAL 4 INP NANO 0.90 ICL7106CPL 3 1/2 DIGIT ND 18.20 74S30N 8 INP NANO 0.95 0.95 ICL7107CPL 3 1/2 DIGIT ND 18.20 74S32N SEE 74AS32N 74S40N 1.05 ICL7109CPL 12 BIT BINARY ND 26.60 DUAL 4 INP BUFFER ICL7129CPL 41 /2 DIGIT ND 74S51N 0.90 38.25 DUAL 2 INP NO/I 74S64N 0.90 ICL7135CPI 4 1/2 DIGIT ND 28.35 4/2/2/3 AND/OR/INVTR 74S65N 4-2-3-2 INP 0.90 ICL7136CPL 3 1/2 DIGIT ND 18.40 ICL8052ACPD 4 1/2 DIGIT INTG ND 74S74N 1.20 2.40 DUAL D FLIP FLOP 1.75 . ICL8053ACPD 3 1/2 DIGIT INTG ND 74S86N 2.40 QUAD EXCLUSIVE OR 1.35 TLC549N 8 BIT ND,SERIAL 74S112N DUAL J-K FLIP-FLOP 3.60 1.20 74S113N DUAL J-K FLIP-FLOP QUAD 2 SCHMITT NANO 1.40 l\Me!.IEEBS 74S132N 74S135N 1.20 QUAD EXCL OR/NOR 1438R WIDEBAND AMP 5.00 1.70 74S136N QUAD 2 INP EX OR 3470P FLOPPY READ AMP 8.50 2.90 74S138N EXP 3/8 DECODER CA3052E QUAD AC AMP 4.40 2.95 74S139N EXP 2/4 DECODER BIMOSAMP CA3130E 3.35 1.50 74S140N DUAL 4 INP NANO DVR BIMOSAMP CA3130T 4.15 2.70 8 INP MUX 74S151N BIMOSAMP 1.45 CA3140E 1.90 74S153N DUAL 4 INP MUX CA3140T BIMOSAMP 1.90 QUAD2/1 MUX 1.90 74S157N DUAL BIMOS AMP 2.15 CA3240E SYNCH DECADE CTR 3.90 74S160N BIMOSAMP 2.00 CA3260E 74S161N PRESET BINARY CTR 2.90 AUTO ZERO AMP 28.65 ICL7605CJN SYNCH DECADE CTR 3.90 74S162N ICL7611DPCA SNGL CMOS AMP 2.30 PRESET BINARY CTR 74S163N 3.90 STABILISED AMP 9.80 74S174N HEX D FLIP-FLOP 1.90 ICL7650CPD QUAD BIFET AMP 3.40 LF347N QUAD D FLIP-FLOP 74S175N 1.90 SINGLE BIFET AMP 2.25 A.LU. 74S181N 6.25 LF351H 1.15 SINGLE BIFET AMP LF351N 74S182N C.L.A. 3.30 DUAL BIFET AMP 2.60 74S188AN 32X8 FAST PROM O.C. 2.40 LF353H DUAL BIFET AMP 2.15 LF353N 74S189AN 16 X 4 TRI-STATE RAM 8.30 SINGLE BIFET AMP 2.95 74S194N 4 BIT UNIVERSAL SIR 2.90 LF355H SINGLE BIFET AMP 2.40 LF355N 74S195N 4 BIT PARALLEL SIR 2.80 SINGLE BIFET AMP 2.95 LF356H 74S196N DECADECTR 3.05 1.10 LF356N SINGLE BIFET AMP 74S197N BINARYCTR 3.25 SINGLE BIFET AMP 1.95 74S240N TRI STATE OCTAL DVR 3.50 LF357N SAMPLE AND HOLD 7.90 74S244N OFFER ALSO 74AS244 3.50 LF398H SAMPLE AND HOLD 6.85 74S251N TRI STATE 2/1 MUX 2.90 LF398N LF400ACH FAST SETTLING AMP 21 .90 74S253N TRI STATE 4/ 1 MUX 2.90 DUAL BIFET AMP LF412CH 4.40 74S257N TRI STATE 2/1 MUX 2.90 DUAL BIFET AMP LF412CN 3.40 74S288AN 2.50 32X8 FAST PROM TS SINGLE BIFET AMP 2.90 74S299N 8 BIT UNIVERSAL S/R 10.50 LF441CH SINGLE BIFET AMP 1.40 LF441CN 74S373N TRI STATE OCTAL LTCH 3.90 DUAL BIFET AMP 2.70 LF442CN 74S374N SEE 74AS374N 4.30 QUAD BIFET AMP 4.70 LF444CN 74S387N 256X4 PROM O.C. 3.00 DIGITAL GAIN BIN 9.35 LF13006N 74S472AN TRI STATE 512X8 PROM 8.80 DIGITAL GAIN LOG LF13007N 9.35 74S474AN TRI STATE 512X8 PROM 9.50 BIFET 741 2.20 74S571N TRI STATE 512X4 PROM 5.50 LF13741H 1.10 BIFET 741 LF13741N 74S573N TRI STATE 1024X4 PROM 7.15 14.90 BUFFER AMP 87S181N TRI STATE 1024X4 PROM 11.85 LH0002CH 13.90 BUFFER AMP 87S185N TRI STATE 2048X4 PROM 13.30 LH0002CN 44.70 1 AMP POWER AMP 87S191N TRI STATE 2048X8 PROM 17.20 LH0021CK 49.75 SAMPLE AND HOLD DM86S64CAB/N CHAR GEN 5X7 UPPER 2.90 LH0023GG 37.60 HI SPEED AMP DM86S64CAH/N CHAR GEN 5X7 LOWER 2.90 LH0024CH 39.70 HI SPEED AMP LH0032CG HI SPEED FOLLOWER 39.70 LH0033CG l\toDandDtol\ 34.40 LO NOISE AMP LH0044CH 89.20 FIBRE OPTIC RCVR 14433 3 1/2 DIGIT ND 14.30 LH0082CD 85.15 PROO GAIN AMP LH0086CD AD581 SEE LH0070-1 H 35.75 FET INPUT AMP LH740ACH AD7520LD SEE DAC1020LCD 11 .00 LO VOLT AMP & REF LM10CH AD7520LN SEE DAC1020LCN 8.45 LO VOLT AMP & REF LM10CLH AD7520UD SEE DAC1020LD 6.10 LO VOLT AMP & REF LM10CLN AD7521UD SEE DAC1220LD 9.50 LM10CN LO VOLT AMP & REF AD7530LD SEE DAC1020LCD LM11CH 9.95 PRECISION DC AMP AD7530LN SEE DAC1020LCN LM11CLH 6.85 PRECISION DC AMP AD7533CD SEE DAC1020LCD LM11CLN 3.35 PRECISION DC AMP AD7533LN SEE DAC1020LCN LM11CN 3.60 PRECISION DC AMP AD7533UD SEE DAC1020LD 1.20 30.10 LM301AH SINGLE AMP ADC0801 LCN 8 BIT ND 1/4 LSB 0.90 SINGLE AMP 11.05 LM301AN ADC0803LCN 8 BIT ND 1/2 LSB LM302H SEE LM310H 7.20 ADC0804LCN 8 BIT ND 1 LSB 1.95 SINGLE AMP 13.05 LM307H ADC0808CCN 8 BIT ND 8 CH MUX 1.00 LM307N SINGLE AMP 9.50 ADC0809CCN 8 BIT ND 8 CH MUX 7.10 LM308AH SUPER GAIN AMP 26.60 ADC0816CCN 8 BIT ND 16 CH MUX LM308AN SUPER GAIN AMP 5.20 15.90 ADC0817CCN 8 BIT ND 16 CH MUX 2.10 LM308H SUPER GAIN AMP 23.55 ADC0820CCN 8 BIT FAST UP COMP SUPER GAIN AMP 0.95 33.00 LM308N ADC0830BCN 8 BIT Nb LM310H VOLT FOLLOWER 4.25 ADC0831CC 8 BIT SERIAL 1/0 7.05 VOLT FOLLOWER LM310N 4.25 8.50 ADC0833CCN 8 BIT SER 1/0 4 MUX SUPER GAIN AMP 6.10 LM312H ADC0838CCN 8 BIT SER 1/0 8 MUX 9.30 LM316H PRECISION AMP 11.45 ADC0844CCN 8 BIT SER 1/0 4 MUX 8.10 LM318H HI SLEW AMP 4.90 39.50 ADC1001CCJ-110 BIT UP CMPTBL HI SLEW AMP LM318N 2.40 ADC1021CCJ-110 BIT UP CMPTBL 42.00 DM81LS98AN TRI ST OCTAL BUFR DM86LS52N SEE 74LS952N DM86LS62N SEE 74LS962N 3.70 LM321AH LM324AN LM324N LM343H LM344H LM346N LM348N LM349N LM358H LM358N LM359N LM3630 LM363H-10 LM363H-100 LM363H-500 LM392N LM709CH LM709CN LM725CH LM741CH LM741CN LM741CS LM741 CN-SGS LM747CH LM747CN LM748CH LM748CN LM1458H LM1458N LM3080N LM3301N LM3401N LM3900N LM4250CN LM13080N LM13600N NE5532AP NE5532N NE5533 NE5534AP NE5534CP OP27GP RC3403N RC4136DB TL061DP TL062CDP TL066CP TL071CP TL072CP TL074 TL081 TL082CP TL084CDP TL084CN UA4136 XR-5533AP XR-5534ACP PRECISION PREAMP QUAD AMP QUAD AMP SEE LM344H HI VOLT/HI SLW AMP PROO QUAD AMP QUAD AMP QUAD AMP DUAL AMP DUAL AMP DUAL HI SPD NORTN INSTMTATION AMP INSTMTATION AMP INSTMTATION AMP INSTMTATION AMP OP AMP/COMPRTOR SNGLAMP SNGLAMP INSTRUMENT AMP SNGLAMP SNGLAMP SGLAMP SGL AMP DUALAMP DUALAMP SNGLAMP SNGLAMP DUAL AMP DUALAMP TRANSCDUCT AMP SEE LM324N SEE LM324N QUAD NORTON AMP PROGRAMM AMP PROG POWER AMP DUAL TRANSCDUCT LOW NOISE DUAL SEE XR-5532CP SEE XR-5533CP SNGL LOW NSE AMP SNGL LOW NSE AMP PRECISION AMP QUAD AMP QUAD AMP SGL LOW PWR AMP DUAL JFET AMP SGLJFET AMP SGLAMP DUAL AMP QUAD AMP SGLAMP DUALBIFET DUAL JFET AMP DUAL JFET AMP SEE XR-4136CP DUAL LOW NSE AMP LOW NOISE AMP 28.60 5.00 0.90 11.40 4.90 1.90 2.95 2.05 1.35 3.15 39.60 24.45 24.45 24.45 2.00 2.55 1.50 9.40 0.80 0.55 0.90 0.45 1.65 1.20 2.05 1.00 2.95 0.90 1.85 1.25 1.10 2.50 2.40 3.10 2.80 3.60 2.80 8.95 2.50 2.30 1.70 2.20 1.60 1.25 1.85 2.75 1.05 1.20 2.50 1.95 4.15 3.55 l\NALQG SWIIQt!l;S AH001 4CD AM3705CN LF13201N LF13202N LF13331N LF13332N LF13333N LF13508N LF13509N DPDT ANLOG SWTCH 8 CHANNEL MUX QUAD SPST SW NC QUAD SPST SW NO QUAD SPST SWITCH QUAD SPST SWITCH QUAD SPST SWITCH 8 CHANNEL MUX 4 CHANNEL MUX 49.95 11.95 7.45 7.45 7.45 7.45 7.45 10.65 10.65 RAPIQLill CIBC!.!IIS 1377P 1496G 3340P 3357P 13020P LM372H LM377N LM378N LM380N LM380N-8 LM381AN LM381N LM382N LM383AT LM383T LM384N LM386N-1 LM387N LM388N-1 LM389N LM390N LM391N-60 LM391N-80 LM391N-100 LM733CH LM733CN DEMODULATOR SEE LM1496H ELECTRONIC ATTEN . NARROW BAND FM IF AM STEREO DECODR AM RADIO CIRCUIT SEE LM2787P SEE LM2878P SNGL2WAMP SGL .SWAMP DUAL LO NOISE AMP DUAL LO NOISE AMP DUAL LO NOISE AMP SNGL8WAMP SNGL8WAMP SNGL5WAMP LOVOLTAMP DUAL LO NOISE AMP 1.5WAMP LO VOLT AMP 1WAMP SEE LM391N-100 SEE LM391N-100 100V AMP DIFF VIDEO AMP DIFF VIDEO AMP 7.45 2.70 2.50 5.70 2.90 2.20 1.95 6.50 3.90 3.45 5.20 5.20 3.55 1.90 2.85 2.50 2.45 2.10 LM739 LM833N LM1304N LM1496H LM1496N LM1875T LM1886N LM1889N LM2879T LM3089N LM3189N LM3820N LMC835N RC4739N TDA1170S TEA5550 XR-4739CP SEE RC4739N DUAL LO NOISE AMP BAL MOD/DEMOD BAL MOD/DEMOD 20 W AUDIO AMP TV VID MATRIX ND VIDEO DEMODULTOR DUAL 9 WATT AMP FM/IF SYSTEM FM/IF SYSTEM AM RADIO 7 BND ST EQLSR DUAL AMP TV VERT DEFLCTN FM RECEIVER SEE RC7439CN 1.90 5.00 5.15 2.30 5.70 8.20 5.75 10.60 4.00 5.25 3.30 11.05 1.60 3.50 5.95 ~ 146818 146818P ICM71701PG MM58167AN MM58174AN MM58274B MM5318N CMOSR.T.C. CMOS R.T.C. CMOS R.T.C. REAL TIME CLOCK REAL TIME CLOCK REAL TIME CLOCK 14.40 10.30 18.75 24.35 22.40 22.40 13.10 llQLil\GE CQMel\BAIQBS LF311H LM211H LM306H LM311H LM311N LM319N LM339AN LM339N LM360N LM360N-14 LM361N LM393N LM710CH LM1414N LM1801N LP339N TL820MJ BIFET .COMPARATOR 10.95 VOLTAGE COMPTOR 3.60 VOLTAGE COMPRTOR 17.15 VOLTAGE COMPRTOR 1.80 VOLTAGE COMPRTOR 1.15 DUAL HI SPEED COMP 2.85 QUAD COMPARATOR 2.70 QUAD COMPARATOR 0.95 HI SPEED COMPRTOR 8.10 HI SPEED COMPRTOR 8.10 HI SPEED COMPRTOR 4.80 COMPARATOR 1.05 SNGL COMPARATOR 1.60 QUAD COMPARATOR 2.70 MICROPOWER CMPTR 5.70 LOW POWER CMPTR 1.55 DUAL COMPARATOR 2.20 CBYSil\!.S CRYS-32KHZ .251N DIAMETER CRYS-1MHZ CRYS-1 .8432MHZ CRYS-2MHZ CRYS-2.4576MHZ CRYS-2.5MHZ CRYS-3.2768MHZ CRYS-3.58MHZ CRYS-3.6864MHZ CRYS-4MHZ CRYS-4. 19MHZ CRYS-4.43MHZ CRYS-4.92MHZ CRYS-5MHZ CRYS-5.068MHZ CRYS-6MHZ CRYS-8MHZ CRYS-9.83MHZ CRYS-10MHZ CRYS-12MHZ CRYS-14.318MHZ CRYS-16MHZ CRYS-20MHZ CRYS-24MHZ CRYS-25MHZ CRYS-27HZ 2.50 9.50 9.50 5.50 5.50 9.50 5.50 2.50 4.40 2.90 2.90 2.90 6.90 2.90 2.90 2.90 2.90 4.90 4.90 2.90 4.90 4.90 4.90 4.90 4.90 4.90 PAil\&QQKS DATA 3200032K SERIES DATA DATA ADV. LOGl74AS/74ALS DATA DATA CONVERS/84 AD/DA CONVRTRS DATA INTFACE/83 INTERFACE DATA DATA INTFACE/86 INTERFACE DATA DATA LIN-1 /87VOLUME 1 LIN DATA DATA LIN-2/87 VOLUME 2 LIN DATA DATA LIN-3/87 VOLUME 3 LIN DATA DATA LOGIC-1 /84 CMOS LOGIC DATA LS/SITTL BIPOLAR LOGIC DATA MICROCON/CONTROLLER DATA DATA NSC800CMOS PROCSSOR DATA DATA SWTCD FILCAPCITVE FILTER DATA TELECOM TELECOM DATA 11.10 7.90 19.00 19.00 15.30 22.50 15.00 15.00 25.00 22.30 22.20 8.00 9.50 11.50 4.00 2.55 1.40 Tax Exempt Prices upon presentation of valid tax exemption certificate - min value $10.00 per line item. Wholesale prices on request. Credit only to established accounts. Cheque, Money Order or Credit Cards with all other orders please. More Products being added daily• such as FACT and AC ranges. Inclusion in listing does NOT guarantee availability. Please check to avoid disappointment ~\)PPO.lf,~\\.Dl.1~ 4 Don't forget to call "Wood for Chips" 427 1676 or Fax 428 5198 t~i ~<tsrRr--V~ IIBIPGE BECIJEIEBS BR34 BRIDGE BR3505 BR354 400V 35A BRIDGE BR64 BRIDG 400V 6A BRIDGE CM3504 IG4B41 400V 1A BRIDGE KBF04 400V 1A BRIDGE MB1505 SOV 15A BRIDGE PK4F 400V 12A BRIDGE SB2 BRIDGE 50V 1A W04 400V 1.SA BRIDGE 0.70 2.85 4.50 3.25 4.90 0.65 1.45 2.65 2.50 0.75 0.50 SIGHAL & BECIIEIEB DIQDES 1N60 GERMANIUM DIODE SIGNAL DIODE 1N914B 1N3070 200V 1SOMA SWITCH 1N4004 400V 1A DIODE 1N4007 1000V 1A DIODE 1N4148 SIGNAL DIODE 1N4936 400V 1A FAST RECOV. 1N5060 SEE GIG045 1N5404 400V 3A DIODE 1OOOV 3A DIODE 1N5408 5082-2800 SCHOTTKY DIODE 5082-2835 SCHOTTKY DIODE A14F SOV/1.SA AVLCH DIODE BB119 20-25PF VARACTOR 34-39PF VARACTOR BB204G BB212 500-620PF VARACTOR 26-32PF VARACTOR B8809 BYW29-150150V SA FAST RECOV. BYW51-150 MR851 100V 3A FAST DIODE ST4 TRIGGER DIODE (DIAC) 0.30 0.10 0.10 0.10 0.15 0.10 0.35 0.15 0.30 0.35 0.95 1.60 0.20 0.55 1.05 5.50 1.00 4.80 4.50 1.50 1.20 ZEHEB DIQDES 1N746A 1N750A 1N751A 1N752A 1N753A 1N958A 1N959B 1N961B 1N962A 1N963A 1N965B 1N967A 1N971A 1N972B 1N974A 1N975A 1N977A 1N4370 1N4371 1N4558B 1N4728A 1N4729A 1N4730A 1N4731A 1N4732A 1N4733A 1N4734A 1N4735A 1N4736A 1N4737A 1N4738A 1N4739A 1N4740A 1N4741A 1N4742A 1N4743A 1N4744A 1N4746A 1N4747A 1N4749A 1N4750A 1N4751A 1N4752A 1N4753A 1N4754A 1N5227B 1N5228B 1N5229B 1N5299B 1N5333B 1N5334B 1N5335B 1N5336B 1N5337B 1N5338B 1N5339B 1N5340B 1N5341B 3.3V 1/2 WATT 5% ZNR 4.7V 1/2 WATT 5% ZNR 5.1V 1/2 WATT 5% ZNR 5.6V 1/2 WATT 5% ZNR 6.2V 1/2 WATT 5% ZNR 7.2V 1/2 WATT 5% ZNR 8.2V 1/2 WATT 5% ZNR 10V1/2WATT5%ZNR 11V1/2WATT5%ZNR 12V 1/2 WATT 5%ZNR 15V 1/2 WATT 5%ZNR 18V 1/2 WATT 5%ZNR 27V 1/2WATT5%ZNR 30V 1/2 WATT 5% ZNR 36V 1/2 WATT 5% ZNR 39V 1/2 WATT 5% ZNR 47V 1/2 WATT 5% ZNR 2.4V 1/2 WATT 5% ZNR 2.7V 1/2 WATT 5% ZNR 3.3V 1 WATT 5% ZNR 3.6V 1 WATT 5% ZNR 3.9V 1 WATT 5% ZNR 4.3V 1 WATT 5% ZNR 4.7V 1 WATT5%ZNR 5.1V 1 WATT5%ZNR 5.6V 1 WATT 5% ZNR 6.2V 1 WATT 5% ZNR 6.8V 1 WATT 5% ZNR 7.5V 1 WATT 5% ZNR 8.2V 1 WATT 5% ZNR 9.1V 1 WATT 5% ZNR 10V 1 WATT 5% ZNR 11V 1 WATT5%ZNR 12V 1 WATT 5% ZNR 13V 1 WATT 5% ZNR 15V 1 WATT 5% ZNR 18V 1 WATT 5% ZNR 22V 1 WATT 5% ZNR 24V 1 WATT 5% ZNR 27V 1 WATT 5% ZNR 30V 1 WATT 5% ZNR 33V 1 WATT 5% ZNR 36V 1 WATT 5% ZNR 39V 1 WATT 5% ZNR 3.6V 1/2 WATT 5% ZNR 3.9V 1/2 WATT 5% ZNR 4.3V 1/2 WATT 5% ZNR 4.7V 1/2 WATT 5% ZNR 3.3V 5 WATT 5% ZNR 3.6V 5 WATT 5% ZNR 3.9V 5 WA TT 5% ZNR 4.3V 5 WATT 5% ZNR 4.7V 5 WATT 5% ZNR 5.1V 5 WATT 5% ZNR 5.6V 5 WATT 5% ZNR 6.0V 5 WATT 5% ZNR 6.2V 5 WATT 5% ZNR 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 1.80 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0'.25 0.25 0.25 0.25 0.25 0.25 0.20 0.20 0.20 0.20 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1N5342B 1N5343B 1N5344B 1N5345B 1N5346B 1N5347B 1N5348B 1N5349B 1N5350B 1N5352B 1N5353B 1N5355B 1N5357B 1N5358B 1N5359B 1N5361B 1N5363B 1N5364B 1N5365B 1N5373B 1N5374B 6.8V 5 WATT 5% ZNR 7.5V 5 WATT 5% ZNR 8.2V 5 WATT 5% ZNR 8.7V 5 WATT 5% ZNR 9.1V 5 WATT 5% ZNR 10V 5 WATT 5% ZNR 11V 5 WATT 5% ZNR 12V 5 WATT 5% ZNR 13V 5 WATT 5% ZNR 15V 5 WATT 5% ZNR 16V 5 WATT 5% ZNR 18V 5 WATT 5% ZNR 20V 5 WATT 5% ZNR 22V 5 WATT 5% ZNR 24V 5 WATT 5% ZNR 27V 5 WATT 5% ZNR 30V5WATT5%ZNR 33V 5 WATT 5% ZNR 36V 5 WATT 5% ZNR 68V 5 WATT 5% ZNR 75V 5 WATT 5% ZNR 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 lt!IEBEACE 3487P SEE DS3487N DH0006CN DS0026CN DUAL MOS CLOCK DVR DS1488N EAI RS232 LINE OVA DS14C88N CMOS RS232 LINE OVA DS1489AN SN75189AN/MC1489AN DS14C89ANCMOS RS232 LINE RCVR DS1489N SEE DS1489AN DS26S11 N QUAD BUS TRCVR DS26LS30CN SEE DS3691 N DS26LS31 CN QUAD DIFF LINE OVA DS26LS32CN QUAD DIFF LINE RCVR DS26LS33CN QUAD DIFF LINE RCVR DS3245N QUAD MOS CLOCK OVA DS3486N QUAD DIFF LINE RCVR QUAD DIFF LINE DVR DS3487N DS3605N DRIVER DS3611N DUAL PERIPHERAL OVA DS3612N DUAL PERIPHERAL OVA DS3613N DUAL PERIPHERAL DVR DS3614N DUAL PERIPHERAL OVA DS3625N TRI STATE MOS OVA DS3630N HEX CMOS COMP BUFR DS3631N DUAL DRVR CMOS COMP OS3632N DUAL DRVR CMOS COMP DS3634N DUAL DRVR CMOS COMP DS3640N QUAD TRI SHARE OVA QUAD MOS CLOCK OVA DS3644N DS3642N DRIVER DS3648N TRI STATE MOS MUX TRI STATE HEX MOS DR DS3649N QUAD TRAPEZOIDAL OVA DS3662N TRI STATE HEX MOS LA DS3675N QUAD NEGATIVE DVR DS3680N DUAL POSITIVE DVR DS3686N DUAL NEGATIVE DVR DS3687N QUAD DUAL DIFF OVA DS3691N TRI STATE DIFF OVA DS3692N RS-485/422 MULTI TCVR DS3695N RS-485/422 XMIT+FAULT DS3696N 120MHz DIVIDE BY 100 DS8629N DS8T26AN TRI STATE QUAD BUS A TRI STATE QUAD DVR DS8T28N QUAD 2 INPUT RCVR DS86!!0N QUAD 2 INPUT RCVR DS8641N DS8692N DUAL LEVEL TRANSL. DS8800H HEX 14V BUFFER O.C. DS8812N DS8820AN DUAL DIFF LINE RCVR 0S88C20N DUAL CMOS RS422/423 DS8822N DUAL LINE RCVR DS8830N DUAL DIFF OVA MM88C30N QUAD LINE OVA DS8831N TRI STATE QUAD OVA OS8832N TRI STATE QUAD OVA TRI STATE QUAD TRCVR DS8833N TRI STATE QUAD TRCVR DS8834N DS8835N TRI STATE QUAD TRCVR QUAD 2 INPUT RCVR DS8836N DS8837N HEX UNIFIED RCVR DS8839N QUAD BUS TRCVR DS8861N 5 SEGMENT LED OVA DS8864N DS8867N 8 SEGMENT LED DVR DS8868N 12 DIGIT DEC/OVA DS8871N LED CATHODE DVR DS8872N 9 DIGIT LED DVR DS8877N HI VOLT 7 SEGMNT OVA DS8880N DS8881N VACUUM FLUORESC D DS8884AN HIGH VOLTAGE DVR MOS/SPERRY OVA DS8885N DS8887N HIGH VOLT SEGMT OVA DS8889N 12.00 4.35 0.90 2.20 0.90 2.20 5.75 2.05 2.25 3.85 5.85 2.70 2.40 3.75 2.15 2.15 2.25 2.15 5.05 2.60 3.70 3.70 3.70 2.05 6.20 2.40 5.45 3.60 7.90 5.70 7.90 8.20 a:20 6.65 7.10 7.00 7.50 10.20 3.00 2.90 2.20 5.20 10.10 5.20 1.80 3.70 11.25 9.20 3.70 5.30 5.75 5.75 4.75 3.70 4.75 3.00 4.35 5.15 3.05 3.90 3.40 2.20 4.10 3.40 1.90 3.05 12.05 5.80 4.40 4.80 6.10 DS36149N HEX MOS OVA DS75107N DUAL LINE RCVR DS75108N DUAL LINE RCVR DS75113N TRI STATE DIFF OVA DS75121N DUAL LINE OVA DS75124N TRIPLE LINE RCVR DS75125N 7 CHANNEL LINE RCVR DS75150N DUAL LINE OVA DS75154N QUAD LINE RCVR DS75160AN IEEE GPIB TCVR DS75161AN IEEE GPIB TCVR DS75176AN SEE DS3695N DS75182N SEE DS8820AN DS75183N SEE DS8830N DS75324N MEMORY DVR/DCDR DS75361N DUAL CLOCK DVR DS75450N DUAL 30V-300MA OVA DS75451N DUAL 30V-300MA OVA DS75453N DUAL 30V-300MA DVR DS75454N DUAL 30V-300MA DVR DS75461N DUAL 30V-300MA OVA DS75463N DUAL 30V-300MA DVR DS75464N DUAL 30V-300MA DVR DS75468N DS75491N 4 SEGMENT LED DVR DS75492N 6 DIGIT LED OVA DS75494N 6 DIGIT LED DVR DS88C120N DUAL CMOS RCVR DS88LS 120 DUAL RS422/423 RCVR ICL232CPE SEE MAX232CPE MAX231CPD RS232 TRMTR/RCVR MAX232CP RS232 TRMTR/RCVR 3.60 2.55 2.55 4.55 2.85 2.15 4.45 2.55 2.55 10.40 10.90 NSB5881 .5IN 4 DIG CC MUX NSB5917 .5IN 4 1/2 DGT C.A. NSB7882 .?IN 2DGTC.A. NSM3914 LINEAR ARRAY+ OVA NSM3915 LOG ARRAY+ OVA NSM3916 LINEAR MODULE NSM4005A NSM39152 LOG ARRAY+ OVA NSN374 .3IN2DGTC.A. NSN381 .3IN 2 DGT C.C. NSN534 .5IN2DGTC.A. NSN581 .SIN 2 DGT C.C. NSN584 .5IN 2 DGT C.C. NSN783 .?IN 2 DGT C.C. 2.05 NSN784 .7IN2 DGTC.A. 4.95 TIL302 .27IN DISPLAY 1.40 TIL303 .27IN DISPLAY 1.05 TIL312 7SEGMNTC.A. 0.80 . TIL327 .3IN 1 1/2 DGT DISP 0.90 1.50 QPTQ CQVPLEBS 1.50 1.50 4N25 OPTO COUPLER PS2021 2.65 4N26 COUPLER 2.SKV 1.90 4N28 COUPLER 0.SKV 1.90 4N33 COUPLER 1.5KV 1.80 4N35 COUPLER 2.5KV TRSTR 9.10 4N38A COUPLER 2.SKV 6.40 6N138 OPTO COUPLER 6N139 COUPLER CTR 2000% 9.30 CNY70 MARK SENSE DTCR 12.50 CNY74-4 QUAD COUPLER MCT2E COUPLER 7.SKV .MEMQBY MOC3021 COUPLER TRIAC OVA MOC3041 COUPLER TRIAC DVR 1402A SHIFT REGISTER 14.80 STIN3101 INTERRUPT DTCR TIL111 1403A SHIFT REGISTER 4.25 COUPLER 1.SKV TRSTR 1024 X 4 STATIC RAM TIL115 2114N 4.50 COUPLER 1.5KV DrrON 2114N-055 1024 X 4 STATIC RAM 1.00 TIL126 . COUPLER SKV TRSTR 4KX8 EPROM 11.50 25320 12.80 PISPLAX DBlllEBS & CQVtilEBS 2564JL 8KX8EPROM 27080 1KX8EPROM 10.00 9.50 14457 27160 2KX8 EPROM BCD/7 SEGMNT DEC/OVA 27C16Q-45 2K X 8 CMOS EPROM 9.85 14458 BCD/7 SEGMNT DEC/OVA 2732A-25JL4 4K X 8 EPROM 8.95 14495P BCD/7 SEGMNT DEC/OVA TMS2532A-25JL 9.80 14419 2/8 KEY/BINARY ENDA 27320 27C32Q-55 4K x 8 550ns PROM ICM7211 AIPL4 DIGIT LED DEC/OVA 5.99 12.5V VPP 9.00 ICM7212AMIPL 4 DIG1T LCD DVR 2764AFI 2764JL-25 8KX8 EPROM 9.00 ICM7216AIJI 10MHZUNIVSL CTR 8.50 ICM7216BIPI 1OMHZ UNIVSL CTR 4KX8EPROM 27640 7.80 ICM7216DIPI 1OMHZ UNIVSL CTR 27C64Q-20 BK X 8 EPROM 27C64Q200 8KX8 CMOS EPRM 200NS 6.00 ICM7217AIPI 4 DGT UP/DOWN OVA 2KX 8 EEPROM 57.00 ICM7217CIPI 4 DGT UP/DOWN OVA 2816J-25 1.90 ICM7218BIJI 8 DGT UNIVSL OVA 4060NL 4116-20NL 16KX1 RAM 5.00 ICM7224AIPI 41/2 DGT CTR/DVR ICM7224IPL 41/2 DGT CTR/DVR 4164-15NL 64KRAM 2.90 3.50 ICM7226AIJI 10MHZ UNIVSL CTR 64KX 1 RAM 4164A-15 4164N-120 64KX 1 DRAM 3.50 ICM7226AIJL 10MHz UNIVSL LED CTR 4256-15NL 256K X 1 RAM 9.10 ICM7227AIPI 4 DGT UP/ON CTR/DVR LM3914N 44·I6-15L 16K X 4 DYNAMIC RAM 5.00 LIN BAR GRAPH OVA 4464-12 64K X 4 DYNAMIC RAM 9.80 LM3915N LOGARITHMIC BAR DVR 5001 15.15 LM3916N VU METER OVA SHIFT REGISTER 15.15 MM5450N 5050 SHIFT REGISTER 34 SEGMENT LED DVR 5501P 256 X 4 CMOS RAM 3.10 MM5451N 35 SEGMENT LED DVR 6116LP-2 2K x 8 CMOS RAM 5.90 MM5453N · 33 SEGMENT LCD DVR 6116LP-3 2K X 8 CMOS RAM 5.00 6116P-3 SEE 6116LP-3 LED LAMPS 6264-15 SK X 8 CMOS RAN 10.80 MINI PHOTO DIODE 8464-15 BK X 8 CMOS RAM 8.80 BPW34 9306N 256 BIT EEPROM 4.70 ESBR5501 200mCd RED LED LR5160RED 5mm RED LED 9345N SEE 9346N SILICON PHOTO TRSTR 27C128 16K X 8 CMOS EPROM 10.80 MEL12 27C256·2 32K X 8 CMOS EPROM 12.95 NSC003 5MM LAMP BEZEL OBSOLETE 27256-25L SEE 27C256Q200 NSL4855 27C256 32K X 8 CMOS EPROM 12.95 NSL4944 5MM CONST CURRENT NSL4955 DELETE 27C256020 SEE 27C256Q200 27C256025 32K X 8 CMOS EPROM 12.80 NSL5053 5MM RED LED 27C512 64K X 8 CMOS EPROM 19.80 NSL5056 5MM RED DIFFUSED NSL5086 3MM RED LED 41256 SEE 4256-15NL 41256A-15L 256K RAM 9.90 NSL5253 3MM GREEN NSL5353 HN6116L SEE 6116LP-3 5MM GREEN LAMP MM5034N 80 BIT OCTAL REGIST 18.25 NSL5386 MM521160WF/N CHARACTER GEN 5.00 NSL6754 SMM RED LED MM52116FDW/N CHARACTER GEN 14.80 NSL57124 RECTANGULAR RED MN3001 26.85 OP20G RECTANG GREEN LED OP20R NMC9306N SEE 9306N RECTANGULAR RED LED OP20Y NMC9346N SEE 9346N RECTANG YELLOW LED TC5501P SEE 5501P Q62902-B156-F2 RT ANG LED HLDR SEL1121R RECTANGULAR RED LED SEL1321G RECTANG GREEN LED LED DISPLAYS SEL1710K 5mm YELLOW LED 9.30 SEL1910D 5mm ORANGE LED 5082-7653 .43IN RED DISPLAY 1.80 HDSP-5303 7 SEGM C.C. SEL2710Y 3mm YELLOW LED HDSP-5503 7 SEGM C.C. 3.45 SEL2310G 3mm GREEN LED CLOCK MODULE 2.00 MA1002B SEL9510G BARGRaPH 5 PT GREEN MA1003 CLOCK MODULE 37.10 SEL9510R BARGRAPH 5 PT RED MA1010B CLOCK MODULE 20.80 TIL213-1 3mm YELLOW LED NSB5382 .SIN 3 1/2 DGT C.A. 12.70 TLHG0400 10mm GREEN LED 1'3.60 16.60 13.60 12.00 12.00 8.70 13.90 12.00 5.20 5.80 5.80 5.80 6.35 6.95 6.95 6.00 6.00 2.00 1.25 · 1.50 1.50 1.50 1.60 1.45 1.70 5.50 6.50 2.50 7.50 1.85 2.55 4.85 4.00 1.20 1.20 1.20 5.90 9.10 4.10 3.70 15.20 1.40 54.00 54.00 54.00 18.25 17.75 · 17.75 23.45 23.45 66.20 66.20 18.25 5.15 5.15 5.15 ' 8.60 8.60 8.60 3.40 0.80 0.15 1.20 0.15 0.15 1.20 0.15 0.15 0.20 0.15 0.30 0.30 0.30 0.15 0.30 0.30 0.25 0.30 0.20 0.25 0.35 0.30 0.40 0.30 · 0.30 3.60 3.60 0.30 1.15 Tax Exempt Prices upon presentation of valid tax exemption certificate - min value $10.00 per line item. Wholesale prices on request. Credit only to established accounts. Cheque, Money Order or Credit Cards with all other orders please. More Products being added daily - such as FACT and AC ranges. Inclusion in listing does NOT guarantee availability. Please check to avoid disappointment 7 1676 or Fax 428 5198 ~ ,. ,,, Don't forget to call " TL HR0400 TL HY0400 TL UR3400 TL UV5300 10mm RED LED 10mm YELLOW LED 3mm RED LED 5mm ORANGE/GREEN LED 1.15 1.15 0.15 1.25 fAL'.I PA L16LSAN OCTAL 16 INP A/O/I PA L 16R4A2NC 35 ns--90ma-20 Pin PA L16R6AN HEX 16 INP RGSTR PA L 16RSANC OCTAL 16 INP RGSTR PA L 16R8N OCTAL 16 INP RGSTR PA L20L 1ON DEC 20INP A/O/XO PA L20XSNC OCT 20 INP A/O/XOR 6.70 6.65 6.65 6.65 5.35 14.55 12.15 ,.,,CBQfBQCESSQBS SEE 6502AB 65 02 8.50 65 02AB 8 BIT UPROCESSOR 8 BIT UPROCESSOR 12.80 6505 8 BIT UPROCESSOR 5.20 65 12 8.50 65 20A 8 BIT P.I.A. 65 21 SEE 6821 8 BIT P.I.A. 8.35 65 22 14.50 65 32AP 128 X 8 RAM/I/O/TMR A.C.I.A. 7.40 65 51 -27 15.00 8 BIT UPROCESSOR 65 C02 11.50 65 SC22P 8 BIT P.I.A. 11.20 8 BIT CPU 68 00P 14.65 8 BIT CPU+ RAM 6802P 18.20 09EB 8/16 BIT CPU 68 18.95 8/ 16 BIT CPU 68 09P 4.90 6821P P.I.A. 10.70 S.S.D.A. 68 52P P.I.A. 6.20 68 821P PROGRAMMABLE TMR 12.55 6840P 11 .30 PROGRAMMABLE TMR 68 840P 49.35 OMA CONTROLLER 68 844P 13.80 CRT CONTROLLER 68 45P CRT CONTROLLER 15.75 68 845P VIDEO DISPLAY GEN. 19.50 68 47P 6.00 A.I.A. 68 ~OP A.I.A. 6.40 68 850P 2 PHASE CLOCK GNRTR 12.35 68 75P 69.50 8 BIT PROCESSOR 80 70N 9.35 2.0US 8 BIT PROCESS 80 BOAN 10.65 8 BIT CPU 80 85A 9.95 80 85AH-2P 8 BIT CPU 14.20 80 C85A 8 BIT CMOS CPU 17.00 81 55 RAM,I/O,TIMER 12.20 82 51 USART 82 53P-5 12.60 TIMER/COUNTER 16.50 82 SSA 1/0 24 LINES 9.50 82 59A INTERRUPT CTRLR 15.00 82C55A 110 24 LINES 146805EP 8 BIT CMOS CPU 11 .95 24.00 680OOC-PlO16 BITCPU 30.00 68705UL3 8 BIT CPU,3.7K PROM EF68840P SEE 68B40P GT E65SC22P SEE 65SC22P 27.75 MM 57409N ARITHMETIC PRCSR SEE NSCS00N-3I NS CS00N 12.60 NSCS00N-1 8 BIT CMOS UPRO 1.0M 28.35 NSCS00N-4 REPLACES NSCSOON-4 NSC810AN SEE NSC810AN-3I 12.60 NS C810AN-1 RAM/ IO/TIMER NS C810AN-4 SEE NSC810AN-4I NS C810AN-4I REPLACES NSC810AN-4I 35.70 13.65 NS C831N-1 1/0 109.00 NS 320810-6 32/16 CPU 6MH2 21 .75 NS 32201N -10 TCU 10MH2 150.00 NSV-32016SK5-6 32016 EVAL KIT 190.00 NSV-32032SK5-6 32032 EVAL KIT R6 502AB SEE 6502AB R65C02 SEE 65C02 R6 532AP SEE 6532AP TM P405-B18N SEE NS405-B18N TS68000C-PIO SEE MC68000C-PIO UM 6520A SEE SY6520A SEE SY6521 UM 6521 UM 6522 SEE SY6522 4.50 28 0A-CPU 8 BIT CPU 9.00 28 0A-CTC 8 BIT CTC 9.90 28 0A-PIO 8 BIT PIO 9.90 28 08-CPU 8 BIT CPU 9.00 28 08-CTC 8 BITCTC 10.00 28 08-DART 8 BIT DUAL UART 11 .90 28 OA-DMA SBITDMA 8 BIT PIO 5.90 28 08-PIO 11.90 28 08-SIO/O 8 BIT SIO 15.00 284C-SIO/O 284C40-4PE 14.25 28 530-SCC S.C.M.P. 7.00 28 4C0004-CPU CMOS ZS0 IELECQM fBQl2UCI MICBQfBQCESSQB fEBlfl:IEBALS FLOPPY SUPPORT LOGIC 1691PE 1771N-1 FLOPPY DISC CTRLR 1772-PH FLOPPY DISC CTRLR 1791-02 FLOPPY DISC CTRLR 1793-02 FLOPPY DISC CTRLR 2143-PD 4 PHASE CLOCK GNRTR 2651N USART 2793A-PI FLOPPY DISC CTRLR 8250AN ASYNCH COMM ELEMENT UART FOR IBM-PS/2 16450N AY-3-10150 UART AY-5-8116 UART DP8212N 8 BIT 1/0 PORT 4 BIT BIOi BUS TRCVR DP8216N DP8224N CLOCK GNRTR/DVR DP8226N 4 BIT BIOi BUS TRCVR SYST CONT & BUS OVA DP8228N 8 BIT BIOi BUS TRCVR DP8303N DP8304BN 8 BIT BIOi BUS TRCVR OCTAL LATCHED OVA DP8310N DP8311N OCTAL LATCHED OVA IM6402IPL 4MH2 UART INS8250N SEE 8250AN INS8250N-B SEE 8250AN NSC858N-4 SEE NSC858N-4I NSC858N-4I REPLACES NSC858N-4 NS82C50AN SEE INS82C50AN NS16450N SEE 16450N NS16C450N SEE INS82C50AN 23.60 25.00 35.00 30.00 25.00 20.90 10.90 48.50 22.00 27.00 12.50 17.50 5.55 3.00 4.65 3.80 12.35 3.70 3.65 9.50 9.50 12.30 19.20 23.10 2681 SEE XR-88C681CP 14409 BIN TO PHONE PULSE 14412 SEE XR-14412VP 68681 SEE XR-68C681CP AF100-1CJ UN IV.FILTEA 2.5% AM7910PC WORLD MODEM AM7911 PC WORLD MODEM AMI S3530P MODEM PHASE LOCKED LOOP L.M565CH LM565CN PHASE LOCKED LOOP LM566CN VOLTAGE CONT OSC. LM567CN TONE DCDR LMC567CN CMOS TONE DCDR MF4CN-50 4TH ORDER FILTEA MF4CN-100 4TH ORDER FILTER MF5CN SNGL ACTIVE FILTER MF6CN-50 6TH ORDER FILTER MF10BCN NOTCH FILTEA MF10CCN DUAL ACTIVE FILTEA NE571N COM PANDER NE572N COMPANDER DTMF TONE DIALLER TP5088N TP5395N DIALLER TSG7515CP MODEM XR-2129CP BELL 212A/V.22 MODEM XR-2216CP MONOLITHIC COMPNDR XR-2567CP DUAL 567 XR-14412VPFSK MODEM SYSTEM 29.65 7.45 7.30 35.95 23.60 35.20 26.10 5.35 2.65 1.70 1.95 2.40 3.50 3.50 3.90 5.05 5.15 6.05 5.90 5.80 3.00 11 .15 55.00 26.05 3.30 4.10 7.30 IEMfEBAIUBESEHSQBS SfECIAL EUHCDQH 1455P TIMER 1.20 VARIABLE MULTIP. 11.20 1495L 18.10 14411 BIT RATE GNRTR 4.95 14490P HEX SWITCH DBNC 8.85 33030P MOTOR CNTRLR 145026P REMOTE CTRL ENCDR 5.00 145028P REMOTE CTRL ENCDR 4.05 CT$256A-AL2 SPEECH CHIP 27.30 ICL8038CCJD FUNCTION GNRTR 7.75 ICM7209IPA 10MH2 CLOCK GNRTR 8.30 12.20 ICM7213IP PRECISION CLOCK ICM7240IJE CMOS TIMER 8.60 10.50 ICM7250IJE CMOS TIMER 1.20 ICM7555CN SEE LMC555CN 1.20 ICM7555IPA CMOS TIMER 3.50 ICM7556IPD DUAL CMOS TIMER 11.05 IM4702IPE BAUD RATE GNRTR LH0094CD ANALOG MATH BLOCK 153.00 PRECISION TIMER 3.40 LM322N LM331AN V TO F CONVERTER 10.05 13.45 LM331H V TO F CONVERTER V TO F CONVERTER 7.70 LM331N CONST CURRENT SAC 1.95 LM3342 TIMER 0.55 LM555CN LM556CN DUAL TIMER 1.05 ULTRASONIC OTA 16.75 LM1812N LM1830N FLUID DETECTOR 4.10 4 CHAN RAD CTR XMIT 8.20 LM1871N LM1872N 4 CHAN RAD CTR RCVR 8.20 LM1893N POWER LINE CARRIER 20.20 F TO V CONVERTER 3.40 LM2907N LM2907N-8 F TO V CONVERTER 4.65 F TO V CONVERTER 4.75 LM2917N LM2917N -8 F TO V CONVERTER 4.75 2.40 LM3905N PRECISION TIMER LED FLASHER/OSCILL 1.90 LM3909N LM7555CN SEE ICM7555IPA LMC555CN CMOS TIMER 1.20 MM5307AA/N BAUD RATE GNRTR 18.50 MM5369AA/N 3.58MHZ/60HZ DVDR 5.15 MM5369EYR/N 3.58MHZ/50HZ DVDR 5.15 MM5740AAF/N KEYBOARD ENCDR 9.90 MM53200N ENCDR/DCDR 8.70 MM54104N SPEECH SYNTHESISER 26.75 MM54240N ASYNCH TMTR/RCVR 15.85 MM57499N KEYBOARD ENCDR 13.10 25.35 MPX100AP PRESSURE XDUCER 22.20 SPO256A-AL2 SPEECH CHIP UA4151 SEE XR-4151CP VDR-VC2130 VOA 0.75 0.75 VDR-VC2275 VOA XR-558CP QUAD TIMER 3.30 XR-2206CP FUNCTION GNRTR 8.90 XR-2209CP PRECISION OSC. 5.20 3.45 XR-2240CP PROGRM.TIMER/CTR XR-2243CP MICROPOWER TIMER 4.20 XR-8038ACP WAVEFORM GNRTR 7.30 XR-8038CP SEE XR-8038ACP AD590JH -55 TO 150C XDUCER 8.00 VOLT MODE TEMP SENS 11 .60 LM135H LM335H VOLT MODE TEMP SENS 3.25 VOLT MODE TEMP SENS 2.75 LM3352 LM35CAH CENTIGRADE SENSOR 13.20 CENTIGRADE SENSOR 14.20 LM35CH 4.30 LM35C2 CENTIGRADE SENSOR LM3502 CENTIGRADE SENSOR 2.65 LM3911 H-46 TEMPERATURE CTRLR 5.15 2.70 LM3911N TEMPERATURE CTRLR 0.30 THERMISTOR-1 50OHM 25 DEG PTC THERMISTOR-2A 13 NTC 1K <at> 20 DEG 3.50 IBAHSISIQBS SCB'&,IBIACS 2N1302 2N1308 2N1711 2N2160 2N2222 2N2222A 2N2369A 2N2644 2N2646 2N2647 2N2904 2N2904A 2N2905A 2N2906 2N2906A 2N2907 2N2917 2N2920 2N3019 2N3020 2N3053 2N3054 2N3055 2N3440 2N3460 2N3546 2N3706 2N3740 2N3771 2N3819 2N3822 2N3829 2N3860 2N3904 2N3905 2N3906 2N3956 2N3957 2N3971 2N3993 2N4032 2N4036 2N4124 2N4288 2N4342 2N4360 2N4401 2N4403 2N4918 2N4921 1.10 1.10 NPN TO39 75V 150mA 2.00 P-N UNIJUNCTION 1.10 NPN TO18 30V 800mA 1.00 NPN T018 40V S00mA 0.95 NPN TO18 15V 150mA 0.85 NPN DUAL TO78 45V 30mA 2.15 UNIJUNCTION TO18 1.20 P-N UNIJUNCTION 1.20 PNP TO39 40V 600mA 1.00 PNP TO39 60V 600mA 1.45 PNP TO39 60V 600mA 1.00 PNP TO18 40V 600mA 1.05 PNP TO18 60V 600mA 1.00 PNP TO18 40V 600mA 1.00 NPNDUAL TO7845V30mA 1.10 NPN DUAL TO78 60V 30mA 6.50 NPN T039 80V 1A 1.80 NPN T039 S0V 1A 1.50 NPN TO39 40V 700mA 0.90 NPN TO66 60V 4A 2.70 NPN TO3 60V 15A 1.40 1.10 NPN TO39 250V 1A 3.90 NFET TO18 50V 1mA 1.90 PNP TO18 12V 50mA 0.30 NPN TO92 40V 50mA 5.15 PNP TO66 60V 4A 5.50 NPN TO3 50V 30A 1.15 NFET TO92 25V 20mA NFET TO18 50V 10mA 2.35 PNP TO9230V 1.90 NPNTO92 30V 0.55 NPN TO92 40V-200mA 0.40 PNP TO92 40V 200mA 0.39 PN P TO92 40V 200mA 0.40 NFET/DUAL 12.75 NFET/DUAL 9.25 NFET TO92 40V S0mA 1.90 PFET TO18 25V 10mA 1.90 PNP TO39 60V 1A 1.90 PNP T039 65V 1A 1.90 NPN TO39 25V 200mA 0.30 PNP TO92 30V 10mA 2.95 3.15 PFET T092 PFET T092 0.90 NPN T092 40V 600mA 0.30 PNP TO92 40V 600mA 0.30 1.65 PNP TO126 40V 1A NPN TO1 26 40V 1A 1.65 2N5086 PNP TO92 50V 10mA 2N5087 PNP TO92 60V 10mA 2N5192 NPN TO126 S0V 4A 2N5210 NPN T092 50V 10mA 2N5458 NFET TO92 25V 9mA 2N5484 NFET T092 25V 5mA 2N5485 NFET T092 25V 10mA 2N5656 NPN T0126 300V 500mA 2N5770 NPN UHF OSCILLATOR 2N5871 2N5944 407-517MHz 2w· 2N5953 NFET/RF/GPA 2N6121 NPN TO126 45V 4A 2N6123 NPN TO126 S0V 4A 2N6706 2N6707 2N6710 2N6725 NPN TO237 60V 0/TON 2N7000 2SB411 2SC935 2SJ49 2SK134 BC107 NPN TO18 50V BC107B NPN TO18 50V BC108 NPN TO18 30V BC177 PNP T018 50V BC178 PNP TO18 30V BC184C NPN TO9245V BC308-92 PNP TO92 30V BC309-92 PNP TO92 25V BC318 NPN TO92 30V BC327 PNP T09250V BC328 PNP T09230V BC337 NPN T092 50V BC337-16 NPN TO9250V BC338 NPN TO9230V BC546 NPN TO9280V BC547 NPN TO9250V BC547B NPN TO9250V BC548 NPN TO9230V BC549 NPN TO9225V BC557 PNPT092 50V BC5578 PNP T092 50V BC558 PNP T092 30V BC558C PNPTO9230V BC559 PNP T092 25V BC639 NPN TO92100V BC640 PNP T092100V BCY71 PNP TO18 45V BCY79-V11 PNP TO18 45V 80136 PNP TO126 45V 1A B0137 NPN TO126 60V 1A 80138 PNP TO126 60V 1A 80139 NPN TO126 S0V 1A 80140 PNP TO126 S0V 1A 80235 NPN TO126 60V 2A 80236 PNP TO126 60V 2A 80439 NPN POWER TO126 80440 PNP POWER TO126 80646 PN P TO220 D/TON 60V 80649 NPN TO220 0/TON 100V B0678 PNP TO126 0/TON 60V 80681 NPN T0126 0/TON 100V 80682 PNP T0126 0/TON 100V BF199 NPN RF AMP BF245C NFET TO92 30V NPN TO126 250V BF258 NPN TO126 250V 100mA BF458 BF470 NPN TO126 300V 50mA BF494 NPN T092 30V 30mA BF495 NPN T092 30V 30mA BF9€0 MFET SOT123 20V BFY51 NPN TO39 60V BFR84 MFET TO72 20V BFR96.02 NPN SOT37 BTY91-800T S00V 25A THYRISTOR BUX0S NPN TO3400V BU210 MFET TO220 50V 12A BU271 C106D SCA 400V 4A C106F SCA 50V 4A 012201 SCA 400V SA DH3725CN QUAD 2N3725 DS7524N QUAD CORE DRIVER FM1109A DUALFET IT1750 N CHANNEL MOSFET SUPERMATCH TRANSIST LM394CH LM394CN SUPERMATCH TRANSIST SUPERMATCH TRANSIST LM394H LM395K POWER TRANSISTOR LM395T POWER TRANSISTOR LM3046N TRANSISTOR ARRAY LM3086N TRANSISTOR ARRAY LM3146N TRANSISTOR ARRAY MJ411 NPN T03 300V 10A MJ423 NPN T03 325V 10A MJ802 NPN T03 100V 30A 5 0.30 0.90 3.30 0.90 0.80 0.80 0.80 4.75 0.30 2.15 3.20 1.90 1.80 1.80 1.00 1.60 1.10 1.20 1.90 1.30 1.10 11 .05 11.05 0.70 0.50 0.70 0.75 0.90 0.35 0.30 0.30 0.30 0.25 0.30 0.25 0.25 0.30 0.35 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.50 0.50 1.80 1.80 0.60 0.60 0.55 0.60 0.60 0.85 0.85 0.85 0.85 1.40 1.60 2.25 1.50 1.50 o.5d 1.80 1.80 1.30 1.60 0.85 0.30 2.50 1.95 5.10 1.10 22.35 5.50 6.00 5.95 0.90 0.70 2.55 3.30 2.20 2.20 5.85 6.55 6.50 7.55 13.30 4.60 1.80 1.80 2.15 7.45 8.35 8.20 Tax Exempt Prices upon presentation of valid tax exemption certificate - min value $10.00 per line item. Wholesale prices on request. Credit only to established accounts. Cheque, Money Order or Credit Cards with all other orders please. More Products being added daily - such as FACT and AC ranges. Inclusion in listing does NOT guarantee availability. Please check to avoid disappointment ._vvP 6 MJ900 MJ1000 MJ1001 MJ2500 MJ2955 MJ3001 MJ4502 MJ11015 MJ15003 MJ15004 MJE340 MJE350 MJE700 MJE800 MJE1100 MJE2955 MJE3055 MJE3055T MJE13007 MPF102 MPSA12 MPSA14 MPSA63 MPSU10 MRF208 MRF571 MRF966 NPDB303 NSD102 NSD106 NSD202 NSD206 PN918 PN2222 PN2484 PN3563 PN3564 PN3565 PN3567 PN3568 PN3569 PN3638 PN3638A PN3640 PN3641 PN3642 PN3643 PN3644 PN3645 PN3646 PN4121 PN4122 PN4250 PN4355 PN4356 PT3164C PT4207B SRF1076 SRF1077 TIC106A TIC106D TIC206A TIC226D TIC246D TIP29C TIP30C TIP31A TIP31B TIP31C TIP32C TIP33A TIP35A Don't forget to call "Wood for Chips" 427 1676 or Fax 428 5198 PNP TO3 60V BA NPN TO3 60V BA NPN TO3 80V BA 5.75 4.30 4.30 10.80 PNP TO3 60V 15A 2.70 7.80 PNP T03 100V 30A 8.30 NPN TO3 400V 50A 22.25 NPN TO3 140V 20A 7.20 PNP TO3 140V 20A 7.80 NPN TO126 300V 500mA 2.45 PNP TO126 300V 500mA 2.65 PNP TO126 D/TON 60V 4A 2.85 NPN TO126 D/TON 60V 4A 2.65 NPN TO127 60V SA 8.90 PNP TO127 60V 10A 2.80 NPN TO127 60V 10A 2.80 NPN TO220 60V 10A 1.80 NPN TO220 400V BA 3.10 NFET/RF 1.00 NPN/DARLINGTON 1.00 NPN DARLINGTON 0.90 PNP DARLINGTON 1.00 NPN CASE 152 300V 0.5A 0.80 3.50 225MHz 10W 6.50 NPNSOE RF NFET SOE 10V 60mA 6.95 DUALNFET 2.45 NPN MEDIUM POWER 1.90 1.90 NPN MEDIUM POWER 1.90 PNP MEDIUM POWER 1.90 PNP MEDIUM POWER 0.30 NPN T092 30V 3mA 0.15 NPN T092 60V 300mA 0.90 NPN TO92 30V BmA 0.25 NPN TO9230V SmA NPN TO92 30V 15mA 0.25 NPN TO92 30V 1mA 0.25 NPN TO92 S0V 150mA 0.30 0.25 NPN TO92 S0V 150mA NPN TO92 B0V 150mA 0.25 PNP TO92 25V 300mA 0.25 PNP TO92 25V 300mA 0.30 PNP TO9212V 50mA 0.30 NPN T092 60V 500mA 0.25 NPN TO92 60V 500mA 0.25 NPN T092 60V 500mA 0.25 PNP T092 45V 300mA 0.25 PNP T092 60V 300mA 0.25 NPN T092 40V 300mA 0.25 PNP TO92 40V 50mA 0.25 PNP TO92 40V 50mA 0.30 PNP TO92 40V 0.1mA 0.25 SEE PN4356 0.30 PNP TO92 80V 500mA 0.25 2.80 2.80 3.50 4W STRIPLINE-2N5945 5.50 100V SA 1.00 TRIAC 400V 4A 1.40 TRIAG 100V 4A 1.80 TRIAC 400V SA 1.90 TRIAC 400V 16A 2.00 NPN TO220 40V 1A 1.00 PNP TO220 100V 1A 1.25 NPN TO220 30V 3A 0.85 NPN TO220 80V 3A 0.90 NPN TO220 100V 3A 1.00 NPN TO220 100V 3A 0.95 NPN TO220 60V 10A 1.75 NPN TO220 60V 25A 2.40 TIP35C NPN T0220 100V 25A 2.80 TIP36C PNP TO220 100V 25A 2.80 TIP41A NPN T0220 60V SA 3.10 TIP41C NPN TO220 100V 6A 1.10 TIP42C PNP TO220 100V SA 1.10 NPN TO220 D/TON 60V 2A 1.25 TIP110 PNP TO220 D/TON 60V 2A 1.10 TIP115 TIP120 NPN TO220 D/TON 60V SA 1.40 TIP122 NPN TO220 D/TON 100V SA 1.70 TIP125 PNP TO220 D/TON 60V SA 1.50 TIP127 PNP TO220 D/TON 100V SA 1.30 NPN TO218 D/TON 60V 10A 3.80 TIP140 TIP142 NPN TO218 D/TN 100V 10A 4.15 PNP TO218 D/TN 100V 10A 2.90 TIP147 PNP TO3 D/TON 60V 10A 2.95 TIP645 PNP TO218 60V 15A 1.90 TIP2955 TN1711 NPN MEDIUM POWER 0.90 NPN MEDIUM POWER 1.00 TN2017 1.00 NPN MEDIUM POWER TN2102 1.00 NPN MEDIUM POWER TN2218A NPN MEDIUM POWER 1.00 TN2270 PNP MEDIUM POWER 1.00 TN2904A PNP MEDIUM POWER 1.00 TN2905A NPN MEDIUM POWER 1.00 TN3020 NPN MEDIUM POWER 1.00 TN3053 PNP MEMORY DRIVER TN3244 0.85 PNP MEMORY DRIVER TN3245 0.85 TN3252 NPN MEMORY DRIVER 0.85 TN3440 0.85 NPN 80V SWITCH TN3444 0.85 PNP MEMORY DRIVER TN3467 0.75 TN3724 NPN MEMORY DRIVER 0.60 TSB3055 NPN TO219 60V 15A 3.00 U310 NFET 4.70 ULN2001 CP SEE XR-2201 CP ULN2002CP SEE XR-2202CP 1.10 ULN2003 NPN DTINGTON ARRAY ULN2004CP SEE XR-2204CP QUAD 50V 1.5A DRIVER ULN2068 3.40 1.25 ULN2208 OCTAL CMOS/TTL DRIVER 2.80 ULN2803 VN10KM NMOSFET TO237 60V 1.90 XR-2201CP TRANSISTOR ARRAY 1.65 XR-2202CP TRANSISTOR ARRAY 1.65 XR-2203CP TRANSISTOR ARRAY 1.65 XR-2204CP TRANSISTOR ARRAY 1.65 XR-2211CP DARLINGTON ARRAYS 7.50 llQLIAGE BEEEBEHCES 1.2V RFRNC ICL8069 ICL8211 CPA PROGRAMMABLE RFRNC ICL821 2CPA PROGRAMMABLE RFRNC ICL8212CTY PROGRAMMABLE RFRNC LH0070-0H 10.000V BIN REFCE LH0070-1 H 10.000V BCD REFCE LH0071-0H 10.000V BIN REFCE 5% VOLTAGE RFRNC LM113H VOLTAGE RFRNC LM313H LM329BZ 6.9V RFRNC 6.9V RFRNC LM329CH 6.9V RFRNC LM329DZ LM336Z-2.5 2.5V RFRNC LM336Z-5.0 5.0V RFRNC LM368H-5.0 PRECISION RFRNC LM368H-6.2 PRECISION RFRNC ADJUSTABLE RFRNC LM385Z LM385Z-1.21.2V RFRNC LM385Z-2.5 2.5V RFRNC TEMP COMP RFRNC LM399H TEMP COMP RFRNC LM3999Z llQLIAGE BEG!.!LAIQBS CURRENT REG 1466L 16.00 ICL7660CPA VOLTAGE CONVERTER 3.60 ICL7663ACPA CMOS REG 6.40 ICL7665BCPA UNDER/OVER DETECT 7.20 2A ADJUSTABLE REG L200C 3.20 LH1605CK SA TO3 SWITCH REG 28.55 LM125H 15V TO5 MIL DUAL REG 18.65 LM304H ADJ 20mA TO5 NEG REG 6.15 LM305AH ADJ 25mA TO5 POS REG 5.90 LM305H ADJ TO5 20mA POS REG 1.80 LM309H SV 200mA TO5 POS REG 5.55 LM309K 5V 1.SA TO3 POS REG 2.85 LM309K-STEEL 5V 1.5A TO3 POS REG 5.90 LM317H ADJ 200mA T05 POS REG 7.15 LM317HVH HIGH VOLTAGE LM317H 11.00 LM317HVK-STEEL H. VOLTLM317HVK 11.00 LM317K-STEEL ADJ 1.5A TO3 POS REG 6.70 LM317KC ADJ 1.5A TO3 POS REG 4.50 LM317LZ ADJ 200mA TO92 POS REG 1.10 LM317MP ADJ 500mA TO202 P REG 1.90 LM317T ADJ 1.5V TO22O POS REG 1.25 LM320H-5.0 5V 500mA TOS NEG REG 9.80 LM320H-12 12V 500mA TOS NEG REG 9.80 LM320H-15 15V S00mA TO5 NEG REG 9.80 LM320K-5.0 5V 1 .SA TO3 NEG REG 7.70 7.70 LM320K-12 12V 1.5A TO3 NEG REG 7.70 LM320K-15 15V 1.5A TO3 NEG REG LM320KC-5.0 SV 1.5A TO3 NEG REG 5.75 LM320KC-1515V 1.5A TO3 NEG REG 5.75 LM320LZ-5.0 SEE LM79L05ACZ LM320LZ-12 SEE LM79L 12ACZ LM320LZ-15 SEE LM79L15ACZ LM320MP-5.0 5V 500mA TO202 N. REG 3.35 LM320MP-1212V S00mA TO202 N. REG 3.35 LM320MP-1515V 500mA TO202 N. REG 3.35 LM320T-5.0 SV 1.5A TO220 NEG REG 4.35 LM320T-12 12V 1.5A TO220 NEG REG 4.35 LM320T-15 15V 1.5A TO220 NEG REG 4.35 LM323K-STEEL 5V 3A TO3 POS REG 7.00 LM325AN 15V OIL DUAL REG 17.00 LM325H 15V T05 DUAL REG 14.50 LM325N 15V OIL DUAL REG 10.95 LM326H 12V TOS DUAL REG 11.95 LM326N 10.95 12V OIL DUAL REG LM330T-5.0 5V 1S0mA TO220 POS REG 1.90 LM333K-STEEL ADJ 3A TO3 NEG RGTL 14.65 ADJ 1.5A TO22O NEG REG 6.85 LM333T LM337H ADJ 200mA NEG REG 8.10 14.15 LM337HVH HIGH VOLTAGE LM337H LM337HVK-STEEL HIGH VOLT LM337K 17.80 LM337K-STEEL ADJ 1.5A TO3 NEG REG 9.35 1.40 ADJ 100mA TO92 N. REG LM337LZ LM337MP ADJ S00mA TO2O2 N. REG 2.05 ADJ 1.5A TO22O NEG REG 2.60 LM337T LM338K-STEEL ADJ SA T03 POS REG 13.50 6.60 LM340K-5.0 SV 1.5A TO3 POS REG LM340K-8.0 SV 1.5A TO3 POS REG 4.00 LM340K-12 12V 1.5A TO3 POS REG 6.60 LM340K-15 15V 1.5A TO3 POS REG 6.60 LM340KC-5.0 SEE LM7805CK LM340KC-12 SEE LM7812CK LM340KC-15 SEE tM7815CK LM340LAH-5.0 5V 100mA TOS POS REG 2.70 LM340LAH-1212V 100mA TO5 POS REG 2.70 LM340LAH-1515V 100mA T05 POS REG 2.70 LM340LAZ-5.0 SEE LM78L5ACZ LM340LAZ-12 SEE LM78L 12ACZ LM340LAZ-15 SEE LM78L15ACZ LM340T-5.0 SEE LM7805CT LM340T-12 SEE LM7812CT LM340T-15 SEE LM7815CT :ros 6.45 3.95 3.95 4.20 10.70 18.30 25.00 20.05 12.05 3.60 5.50 0.95 1.95 1.95 12.15 12.15 2.85 2.85 2.85 6.30 4.90 111 -"t ,till tt,,i- LM340T-24 SEE LM7824CT LM341P-5.0 SV S00mA TO202 POS REG 1.35 LM341P-1212V S00mA TO202 POS REG 1.35 LM341 P-151 SV S00mA TO202 POS REG 1.35 LM341T-5.0 SV 750mA TO22O POS REG 1.40 LM341T-1212V 750mA TO220 POS REG 1.40 LM341T-1515V 750mA TO22O POS REG 1.40 LM342P-5.0 5V 250mA TO2O2 POS REG 1.25 LM342P-1212V 250mA TO2O2 POS REG 1.25 LM342P-1515V 250mA TO2O2 POS REG 1.25 LM345K-5.0 SV 3A TO3 NEG REG 16.70 LM345K-5.2 5.2V 3A TO3 NEG REG 16.70 LM350K-STEEL ADJ 3A T03 POS REG 9.80 LM350T ADJ 3A TO220 POS REG 7.75 LM376N ADJ 45mA OIL POS REG 1.05 LM396K-STEEL ADJ 10A TO3 POS REG 32.50 LM723CH ADJ 150mA T05 POS REG 2.40 LM723CN ADJ 150mA OIL POS REG 0.75 LM2930T-5.0 5V 150mA TO220 LO 1/0 2.20 LM2930T-8.0 BV 150mA TO220 LO 1/0 2.20 LM2931AT-5.0 SEE LM2931T-5.0 LM2931AZ-5.0 SEE LM2931Z-5.0 LM2931CT ADJ 150mA TO220 LO 1/0 3.10 LM2931T SEE LM2931 CT LM2931T-5.0 5V 150mA TO220 LO 1/0 1.95 LM2931Z-5.0 5V 150mA TO92 LO 1/0 1.35 LM2925T LO DROPOUT WTH RESET 4.75 LM2935T LO DROPOUT DUAL REG 4.90 LM2940CT-5.0 5V 1.5A T0220 LO 1/0 2.85 LM3524N PULSE WIDTH MODULAT 3.65 LM7805CK 5V 1.5A TO3 POS REG 2.40 LM7805CT 5V 1.5A TO22O POS REG 0.80 LM7808CK BV 1.5A TO3 POS REG 3.90 LM7812CK 12V 1.5A TO3 POS REG 2.40 LM7812CT 12V 1.5A TO220 POS REG 0.80 LM7815CK 15V 1.5A TO3 REG 2.40 LM7815CT 15V 1.5A TO220 POS REG 0.80 LM7818CT 18V 1.5A TO220 NEG REG 1.10 LM7824CT 24V 1.5A TO220 NEG REG 1.10 LM78L05ACH 5V 100mA TO5 POS REG 2.00 LM78L05ACZ 5V 100mA TO92 POS REG 0. 75 LM78L06ACZ 6V 100mA TO92 POS REG 0.90 LM78L08ACZ 8V 100mA TO92 POS REG 0.80 LM78L12ACH 12V 100mA TO5 POS REG 2.10 LM78l12ACZ 12V 100mA TO92 P. REG 0.75 LM78L15ACH 15V 100mA TO5 POS REG 2.10 LM78L15ACZ 15V 100mA T092 P. REG 0.75 LM78L18ACZ 18V 100mA T092 P. REG 0.80 LM7905CK 5V 1.5A TO3 NEG REG 4.15 LM7905CT SV 1.5A TO220 NEG REG 0.95 LM7908CT 8V 1.4A TO220 NEG REG 1.60 LM7912CK 12V 1.5A TO3 NEG REG 2.50 LM7912CT 12V 1.5A TO220 NEG REG 0.95 LM7915CK 15V 1.5A TO3 NEG REG 2.50 LM7915CT 15V 1.5A TO220 NEG REG 0.95 LM7918CT 18V 1.5A TO220 NEG REG 1.60 LM79L05ACZ 5V 100mA TO92 NEG REG 1.10 LM79L 12ACZ12V 100mA TO92 N. REG 1.10 LM79L15ACZ15V 100mA T092 N. REG 1.10 LM79M05CP 5V S00mA TO202 N. REG 2.15 LM79M12CP12V S00mA TO202 N. REG 2.15 LM79M15CP15V 500mA TO202 N. REG 2.15 LMC76601N SEE ICL7660CPA LP2950ACZ-5.0 5V TO92 UPWR P. REG 3.30 LP2950CZ-5.0 5V TO92 UPWR P. REG 2.85 LP2951ACN ADJ OIL UPOWER P. REG 4.25 LP2951CN ADJ DIL UPOWER P. REG 3.90 LP2951H ADJ TOS UPOWER P. REG 19.90 RC4195K DUAL 15V 200mA REG 3.60 TL494CN FIXED FREQUENCY PWM 2.00 TL496CP 1.50 TL497ACN SWITCHING REG 4.80 Geoff Wood Electronics Pty Ltd Incorporated in N. S. W. I L~} "~~.~ 229 Burns Bay Road, (Corner Beatrice St), Lane Cove West I ~ P.O.Box 671 Lane Cove N.S. W. 2066 Telephone : (02) 427 1676 Fax :(02) 428 5198 BEATRm T 8.30am to 5.00pm Monday to Friday 8.30am to Noon Saturday PENR O S E <at> ,r Mail Orders add $3.00 to cover postal charges ii GL.AJillLE Next day delivery in Sydney add $5.00 OR,ooe • All Prices include Sales Tax Tax exemption certificates accepted if line value exceeds $10.00 Bankcard, Mastercard, Visa, Cheques or Cash cheerfully accepted 7 I Tax Exempt Prices upon presentation of valid tax exemption certificate - min value $10.00 per line item . Wholesale prices on request. Credit only to established accounts. Cheque, Money Order or Credit Cards with all other orders please. More Products being added daily - such as FACT and AC ranges . Inclusion in listing does NOT guarantee availability. Please check to avoid disappointment BUILD TIHS SLAVE FLASH TRIGGER When your camera's flashgun fires, this simple device automatically detects the flash and triggers a second (slave) flashgun. It's easy to build and can be put together for less than $20. By JOHN CLARKE & GREG SWAIN Commercial slave flash triggers are expensive so you can save money by building one yourself. As you'll see, only a handful of parts is required and the unit will only take an hour or so to put together. But why would you want one? Let's find out. While a single flashgun may be adequate in some situations, it often causes harsh shadows because the light is only coming from one direction. Alternatively, the photograph can appear to lack contrast and depth, particularly if 01 FPT100 B A + HOT SHOE ADAPTOR 470k SLA~~Jh~SH VIE~:ea:oM ~ ~ Fig.t: the circuit uses a phototransistor (Qt), an SCR and a few resistors. When a high-intensity flash occurs, Qt conducts and turns on the SCR which triggers the slave flashgun via the hot shoe adapter terminals. all the light is coming directly from the front. The best way around these problems is to employ a second flashgun. By correctly positioning and aiming this second flash, you can fill in any shadows that would otherwise be created and greatly improve the "depth" of your photographs. You can also use a second (or even a third or fourth) flash to light the background behind a subject. Of course, for this scheme to work, the multiple flash units must be made to fire at the same time. This can be done by simply connecting them in parallel to the camera's flash socket via a multiway adaptor cable. Although this technique generally works OK, cable-connected flashguns do have their limitations. For example, you may be prevented from positioning a flashgun exactly where you want it because the cable isn't long enough. Cables are also a nuisance - they're easy to trip over, they get in the way, and they're often unreliable. A far better method is to use an electronic slave flash trigger such as the unit to be described. This device automatically triggers a APRIL 1988 47 PARTS LIST 1 plastic case, 83 x 54 x 28mm 1 PCB, code SC13-1-588, 44 x 26mm; or 1 piece of Veroboard, 44 x 26mm 1 Scotchcal label (optional) 1 SPOT toggle switch 1 9V battery 1 battery clip to suit 1 LED bezel 4 rubber feet 1 hot shoe adaptor (available from photographic stores) 1 C106D SCR 1 FPT1 00 phototransistor 1 470k0 0.25W resistor 2 1 kO 0 .25W resistors Miscellaneous All the parts fit easily inside a small plastic jiffy case. The PCB is held in place by the phototransistor which is clipped into a LED mounting bezel. Fig.2: wiring diagram for the PCB version. The SCR is mounted flat against the PCB while the phototransistor should be stood off the board by about 10mm. slave flashgun whenever it detects high-intensity light from the primary flashgun. This eliminates trailing cords which means that you can place the slave flashgun anywhere you want. The performance of our "homebrew" unit is on a par with expensive commercial units. It has excellent sensitivity, will not false trigger, and uses readily available parts. How it works Take a look now at Fig.1. The circuit is really very simple. It uses a phototransistor (Ql), an SCR (C106D1), three resistors and a 9V battery. The SCR takes the place of the camera contacts and is wired 48 S/IJCON CHIP 0 O , CA O o o c \.cl 0 000 00 0 000 Solder, screw for hot shoe adaptor, shielded cable, hookup wire. of this resistor (ie, by tying the base more firmly to ground). The lkO resistor between the gate and cathode of the SCR prevents the SCR from false triggering if high voltages are applied between the anode and cathode. Power for the Slave Flash Trigger is derived from a 9V battery. On/off switch Sl disconnects power when the Slave Flash Trigger is not in use. Assembly Fig.3: parts layout for the alternative Veroboard version. across the trigger circuit of the flashgun. Normally, the SCR is off and so the flashgun is able to charge to its trigger voltage. Phototransistor Ql is used to monitor the light level. When a high-intensity flash occurs, Ql briefly conducts and supplies gate current to the SCR. This causes the SCR to turn on which then triggers the slave flashgun via the hot shoe adapter terminals. Once the flashgun has triggered, the SCR quickly turns off again. The reason for this is that the current in the flashgun circuit quickly falls below the SCR's holding current. The 470k0 resistor at the base of Ql sets the sensitivity of the circuit. If you wish, you can reduce the sensitivity simply by reducing the value We made up two versions of the Slave Flash Trigger - one on a small PCB (printed circuit board) and the other on Veroboard. Fig.2 shows the wiring diagram for the PCB version while Fig.3 shows the Veroboard version. The PCB for this project is coded SC13-1-588 and measures 44 x 26mm. Install the parts as shown in Fig.2, with phototransistor Ql mounted about 10mm proud of the PCB. The body of the SCR should be mounted flat against the PCB, and its leads bent at right angles to mate with the appropriate holes. Assembly of the Veroboard version is similar to the PCB version. You can make cuts in the copper tracks using an oversize drill bit. Be careful when using Veroboard though - it's very easy to make a mistake. We mounted the completed board assembly in a small plastic ;t Above are actual size artworks for the PC pattern and the front panel. The board should only take a few minutes to assemble, no matter which version you choose to build. The phototransistor must be clipped into a LED bezel at one end of the case so that it is exposed to the ambient light. case measuring 83 x 54 x 28mm. This case is used upside down, with the lid becoming the base. The hot shoe adaptor is secured to the top of the case using a screw, while the on/off switch is mounted at one end. A third hole is drilled at the other end of the case to accept a mounting bezel for the phototransistor. The board is then supported ver- Mailbag On examination however, the article in question was found to suffer from several inaccuracies which detracted from the quality of the information provided. The following aspects are of particular concern: continued from page 3 cold.climates, weldm esh will quickly ice up and then present very high windage. Similarly, solid sheet bow-ties have much higher windage and work no better than the vestigial bow-ties we have specified. As far as our dimensioned diagrams are concerned, we try to include all the relevant dim ensions without making t'he diagrams too crowded and difficult to follow. Hazards of the MEN system I refer to an article entitled, "Your House Wiring Could Kill You" which was recently brought to the attention of this Department. The article appeared in the November 1987 issue of SILICON CHIP. As you may be aware, the Department of Energy has a responsibility to promote correct electrical installation practices and the safe end use of electricity in New South Wales. Magazine articles which assist in the promotion of electrical safety are always welcomed by this Department and your interest in this important issue is commended. (1). The incorrect statement that the resistance of the return path through the ground is consistently lower than the resistance of the neutral return path in the MEN system, resulting in substantial currents flowing in the earthing conductors of the installation under normal operating conditions. (2). The implication that the loss of the earth connection and neutral connection due to corrosion can be expected as a normal course of events. (3). The suggested method of calibration for the makeshift clamp-on meter requiring contact with live single insulated conductors. (4). The photograph (page 80) depicting the makeshift clamp-on meter utilising the 'old relay' is misleading. It does not show the live conductor passing unbroken through the relay; it could be misconstrued that the live conductor is connected to the relay frame or coil. tically in the case when the phototransistor is clipped into the bezel (see photograph}. Figs.2 and 3 show how to connect the board to the on/off switch, battery and hot shoe adaptor. Note that some flashguns do not include a hot shoe plate. In that case, just delete the hot shoe adaptor and connect a cable and plug (to suit the flashgun trigger socket} instead. Just remember - the centre terminal of the plug is positive (ie, it goes to the anode of the SCR}. To test the unit, simply connect it to a flashgun, switch on, and check that the flashgun fires whenever the primary flash connected to the camera fires. You should find that the unit will trigger reliably at distances of up to 15 metres or more. Finally, here's a rather unusual application for your slave flash trigger. If you have a motor drive, you will probably find that the slave flash trigger will trigger that as well (depends on the motor drive}. This means that you can set a motor driven camera up some distance away and trigger it by setting off a flash. 1b (5). The advice that the consumer may repair the main earth connection is not supported. Such repairs are within the scope of electrical wiring as defined by legislation; consequently the involvement of a licensed electrical mechanic is mandatory. The above criticism is offered in the interest of the consuming public. You would no doubt agree that accuracy is essential if the article is to expect credibility from the technically informed reader and avoid panic in the technically uninformed. It is recommended that in future any information of this nature be thoroughly checked by a suitable qualified person prior to publication. N.C.Watson NSW Department of Energy Comment: we are not happy with this statement from the NSW Department of Energy. It is more concerned with criticising the detail of the article rather than addressing the real problem, a dangerous j]aw in the M.E.N. system. We have written to the Secretary to ask if the Department has a policy on this topic and if not, whether such a policy will now be formulated. We will publish details as they come to hand. APRIL 1988 49 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. High speed pulse amplifier This circuit is a small high speed pulse amplifier using discrete components in preference to integrated circuits, to keep the cost of parts low. Essentially, the circuit uses a differential pair, Ql and Q2, followed by grounded base amplifier Q4. The output of Q4 is then buffered by emitter follower stage Q5. Feedback is via R3 to the base of Q2. As shown, the amplifier is set up in inverting mode but could be used as a non-inverting amplifier simply by connecting the input signal to the base of Ql. The circuit has been kept simple to maintain stability with wide bandwidth. The trade-off is that open loop gain is modest, being about 300 at DC. The circuit will not deliver large negative signals, as it was designed to deliver positive pulses only. If negative signal capability is required instead, the polarity of the entire circuit can be changed by replacing all NPN transistors with PNPs and vice versa. Similarly, the supply voltages and the polarity of electrolytic capacitors should be reversed. 130!) 05 2N2369A .,. ~ OUTPUT 2.7k D2 1N914 4.7k .,. 0,1 1k ~ *SEE TEXT ------------,------------12v Output capability is 5V into 500 (ie, lO0mA). Set for a gain of 10 (with Rl, R2 = 1000, R3 = lkO and Cl = 2pF approx.), the risetime is 5ns for 500mV peak output and l0ns for 5V out. This corresponds to a small signal bandwidth of 70MHz and a slew rate of 400V/µ,s. Set for unity gain (with Rl, R3 = 4700, R2 = 560 and Cl = 5.6pF), the risetime is 2.5ns for 500mV peak output. This corresponds to a bandwidth of 140MHz. For maximum performance the amplifier must be built on doublesided printed board with the component side being a large groundplane. All signal connections must be made via coax cable which ideally should be soldered directly to the board. It is also important that Q4 be correctly biased otherwise unequal rise and fall times may result. The value of R4 may need fine adjustment if this is a problem. $20 to: Phil Denniss, University of Sydney. Headphone noise monitor for power amplifiers This circuit was found to be useful when we were checking the prototype of the Studio 200 power amplifier presented in the February 1988 issue of SILICON CHIP. While an oscilloscope and AC millivoltmeter are essential tools in optimising an amplifier design for minimum residual noise, the most effective test is to listen to it. But, as with most modern amplifiers, the Studio 200 is so quiet that it is difficult to hear any sounds at all even 50 SILICON CHIP 4!l HEADPHONES 5W 2x1N4001 FROM AMPLIFIER OUTPUT when your ear is close up to a loudspeaker. The alternative is to directly connect a pair of headphones across the loudspeaker terminals. This gives a very sensitive monitor but is dangerous because any signals accidentally applied to the amplifier's input may severely overload the headphones. In bad cases your ears may be damaged and the headphones may be completely burnt out. To prevent serious overloads, we used the accompanying circuit. It uses a pair of crossconnected diodes to limit the voltage across the headphones to about 0.6 volts peak. The 40 5W resistor limits the current through the diodes to a safe value. +12V 16 .u. 01 3x1N914 .JZ.. 02 BUZZER 10 A 12 03 IC1 CD4043 ':" 04 1N914 ::- ':- .,. LED1 .,. 220k 14 8 + 47I- .,. 47k .,. READY LED4 .,. I\ 15 .,. .,. -:6 Quiz game using a CMOS latch These days it seems a quiz cannot be carried out without the aid of an electronic judge to see which super-brain hit the button first. Maybe it's a test of reactions rather than knowledge. Nevertheless, for those who are fast on the button, here is a quiz game adjudicator which uses two CMOS chips, the 4043 and a 4584 (or 74C14). The 4043 is a package containing four RS latches which goes by the .,. IC2c s5 full title of quad 3-state RS latch. Each of the four latches has a Set and a Reset input. In this circuit, three latches are used and so three buttons are connected to the Reset inputs, pins 4, 6 and 12. The associated latch outputs, pins 2, 9 and 10, are normally low. The first button to be closed will latch the associated output high and light the associated LED. This will cause the input of Schmitt trigger IC2c to go high and its output to go low, which removes the + 12V to the switches and prevents the other latches from working. $20 to Dave Duffy, Thornlands, Qld. Handy hints VU meter for tape dubbing Some of the cheaper tape decks and portable cassette recorders do not have adequate level meters. That is the reason for this circuit which is intended for monitoring the signal level when dubbing tapes. The meter pointer starts to move at below 100 millivolts and it is substantially linear from 200 millivolts to the full scale reading of 1 volt. The circuit is a class-B detector with Ql biased just at the point of conduction. The collector current of Ql is an amplified and half-wave rectified version of the input signal. To calibrate the meter, set VRl at minimum resistance and VR2 at maximum before swit- When the first latch goes high, IC2b and IC2a deliver a pulse to turn on transistor Q1 to sound the buzzer for one second. Some seven seconds afterwards, as set by the 220k0 resistor and the 47 µF capacitor, the output of IC2d goes high to reset all the latches. The circuit could be modified to cater for four contestants by connecting a button to pin 15 of ICl (ie, disconnect pin 15 from OV). At the same time, pin 14 should be connected to pin 11. Hint #1: Mica washers for moun- ting T0-220 transistors can often be hard to get. especially on a Saturday afternoon when all the parts shops have closed. If you have a T0-3 mica washer though, it is a simple job with the scissors to convert it to two T0-220 mica washers. ching on. VRl should be increased until the pointer is a little above zero reading (ie, Ql just biased into conduction). Then apply an audio signal of 1 volt RMS and adjust VR2 for full scale reading. Depending on the gain of the transistor used, the 2200 emitter resistor may need to be increased to 3300. $15 to: J. Emery, Bull Creek, WA. Hint #2: Need to temporarily mount a loudspeaker in a cabinet but don't wish to use caulking compound to make the seal? A ring of thick corrugated car.dboard can suffice for this jo~ provided i t is not overcompressed. As an alternative, foam-backed draught-exclusion tape is suitable. Which ever you use, check for air-leaks before doing any other tests. / \1'/lll. UJ88 51 The ONLY Answering Machine for the Electronics Enthusiast • To most people, an answering machine Is an answering machine. You plug It In, turn it on, and It works. As an electronics enthusiast, you need to know more .. . you want to know not only what It does, but.how It does it. What's Inside It, what makes It tick. And so on. Take a close look at the new Dick Smith Electronics Message Forwarding Answering Machine. You won't be disappointed! • For a start, It's fully microprocessor controlled. This reduces its mechanical complexity dramatically, also reducing its mtbf. • All functions are "soft touch" push button controlled, monitored by Its microprocessor. Where applicable, LED Indicators show functions selected. • Specially developed high torque motors mean any standard cassette can be used - not some high priced "special". • Virtually all functions are fully accessible from any phone with DTMF dialling capability. In addition, an optional DTMF pad Is available for use with standard Telecom phones. so What Does It D07 Obviously, It's an answering machine. But It's more: much more. It offers several unique features which, until now, have been unheard of at anything like the price: • It automatically dials a chosen number, waits for a voice to answer, then tells that number that a message Is waiting. All this within a few seconds of the message being left! · • It has built-In security: you can ring In from another phone, but you need to enter a chosen code before you can listen to any mesages. • it has a superb security feature: an external switch Is supplied which causes the machine to dial a chosen number, wait for a voice, then play an emergency message. Think of the applications In home/building protection, elderley or Infirm care, etc. • It has another unique security feature: ring your own number, enter a code and "listen In" to the surrounding area via the Inbuilt microphone! • It has more, much more than we could possibly tell you about here. Who Needs An Answering Machine, Anyway? You do! Just think: how many times have you raced to the ringing phone and . . . Just missed It! or be told "I've been trying to ring you all day . . ." Answering machines have always made sense for business. Now, due to the Incredibly low DSE price, they make sense for the home as well. And as a hobbyist, you'll appreciate the exceptional value and quality this superb machine offers. ALL THIS POR ONLY Try It - At Our Risk! You know about our satisfaction Guarantee: buy the machine, try It for seven days and if you're not completely delighted, return it in original condition and packaging for a full refund! cat F-6145 • NSW • Albury 21 8399 • Bankatown Square 707 4888 • Blacktown 671 7722 • Bondi Junction 3871444 • Brookvale (Warrlngah Mall) 93 0441 • Campbelllown /046)27 2199 • Chalswood Chase4111955 • Chullora 642 8922 • Gore HNI 439 5311 • G - . i 25 0235 • Hom1by477 6633 • Llverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newculle 611896 • N - Ryde 88 3855 • Parramatta 689 2188 • Penrith /047)32 3400 • Raffway Square 211 3777 • Sydney Cily 267 9111 •Tamw- 66 1711 • Wollongong 28 3800 •ACT• Fyahwlck 80 4944 •VIC• Ballarat 31 5433 • Bendigo 43 0388 • Box Hiil 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Eaaendon 379 7444 • Footacray 689 2055 • Frankaton 783 9144 • Geelong 43 8804 • Melbourne Cily 670 9834 • Richmond 428 1614 DICKeSMITH :~~=-8 ELECTRONICS ~~:ti~; !f.'!:r.~: ~:~ ~;~~: i~kh::~:~e2~i~JJ~ ~3~~:,~~~d;::; f?:.;;:;.r;: it~~ PTY LTD • Townavffle 72 ·5722 • Underwood 341 0844 • SA• Adelaide Clly 2321200 • Beverley 3471900 • Darlington 298 8977 • l!llubeth 255 6099 • Enfield 260 6088 •WA• Cannington 451 8666 • Fremantle 335 9733 • North Perth 328 6944 • Perth Clly 481 3261 • TAS • Hoba,t 31 0800 •NT• Sluart Park 81 1977 Order b y ~ Toll Free (008) 22 8810 for DSXpresa 24 hour Deapalch. World Radio TV Handbook 1988 edition! Frequencies, addresses, call signs, ID's... It's all here! A complete, comprehensive listing of international radio and TV stations. A must for the serious and not-soserious amateur. Cat B-2088 Now In Hardback/ 13.8V <at> 4 Amps Regulated 13.8V 2A Supply 1988 ARRL Handbook The amateur bible is now exclusively in hardback! This new 1988 edition has heaps of new construction projects as well as the usual up-to-date theory you've come to expect from the world's leading amateur handbook. Cat B-2221 The Panther Power Supply is ideal for CB's, car radios, small amateur transceivers (especially hand-helds), etc, etc! 13.8 volt DC regulated power supply with easy screw connections. Makes a great service supply too! Cat M-9545 When you need a bit more punch - this is the one you'll want. The high power panther that's ideal as a bench supply for service work, a supply for 'auto' equipment, all 2m or smaller HF amateur, etc, etc. Gives 3 amp continuous or 4 amps at 75% duty rating. Cat M-9547 s99 Still Only s4995 Zippy Boxes With 2 Lids! You can't beat the genuine DSE Zippy Box for quality or versatility! The deep ribbed sides are ideal for mountin~ PCB's (without screws!) and with both recessed aluminium and moulded plastic lids it's like getting two for the price of one. Pl Ull 50 X 90 X 150mm Cat H-2851 $3.95 Pl 012 60 X 113 X 196mm Cat H-2852 $5.50 Pl 013 41 X 60 X 130mm Cat H-2853 $3.15 Pl. UB5 28 X 54 X 83mm Cat H-2855 $2.30 SAVE 1011/ol "Clean Power" Spike, Surge and Noise Profection Argus Desk Lamp 7.5x magnification Desk Lamp that's perfect for working on electronics or anything that requires handling small parts, etc. With foldin~ swivel arm so you can get 11 into just the right spot. Cat S-4000 This has to be one of the best ideas in years! A six way power outlet with inbuilt spike and surge protection PLUS a hi~h frequency noise rejection ftlter. Fantastic for computers, hi-fi, TV ... anything! Look what you get • Surge & Spike Protection • HF noise rejection filter • 6 outlets with safety shutters • Master d/pole switch and 2 metre cord Cat P-5618 Was$99.95 95 Only 5 89 International Mains Socket Adaptor Just the thing for the regular traveller! Converts our standard 3-pin plug into virtually anything used in the world. Everything's one piece so there's nothing to lose. Be careful though, if doesn·t convert voltage! cat P-5652 NEED A SWITCH?? Professional Performance... 6.5MHz CRO Perfect for the hobbyist's workbench, service dept or classroom. The inexpensive CRO that gives all the performance and reliability of professional models. The features speak for themselves • Retrace blanking for clearer display • 10Hz to 100kHz, plus external timebase • 10mV per division vertical sensitivity • 250mV/division external horizontal sensitivity • Internal and external sync. • Usable response to beyond 6.5MHz • Great low price! Cal 0-1280 ,399 MINIATURE TYPES SPOT - Body 8mm x 13mm, clearance 17mm. 125V AC 5A $1 .75 (240V AC 2AI Cat S-1173 OPDT - Body 13mm x 13mm, clearance 17.5mm. 125V AC 5A (240C AC 2AJ Cat S-1174 $1.95 125V AC 5A (240C AC 2AJ Cat S-1286 $2.50 OPDT Cent11 Off - Body 12mm x 12mm, clearance 20.5mm. DPDT Cenl11 Off Mo1111nl1ry One Side - As S-1286, but with a spring-return momentary position on one side. 125V AC 5A Cal S-1287 $4.50 Heavy Daly DPOT - An enormous contact to size ratio. Ideal for use where high power levels are involved. 125V AC 10A Cat S-1168 $4.95 ECONOMY TOGGLE Standard SPST - Awell designed switch in a bakelite case. Ideal for electric projects and automotiv~ use. 125V AC 3A Cat S-1215 St.95 St11d1nl DPDT - Same general features as the above switch. 125V AC 3A (240V AC 1.5V) Cat S-1216 $2.25 MOllltnllry Action Cenl11 Off - Low voltage, high current swtich for vehicle applications. 12V DC 20A Cat S-1085 $4.50 Dasllboanl Switcll - Pull on, push off single pole switch as found in many older vehicles (lights, wipers, etc.) 12V 10A Cat S-1190 $4.50 PCB Moanling l'lsll Blllton - Similar to above, but with right angle legs for pcb mounting through panel. 120V AC 1A Cat S-1253 $2.95 PCB Mo■nling Cent11 Off - Right angle legs for pcb mounting, double pole changeover type with centre off position. 120V AC 1A Cat S-1251 $3.25 PCB Mounlint Cllanaeover - As above, but without the centre off position. Also rated fiigher: 250V AC 1A (120V AC 3AJ Cat S-1249 $2.95 Wllerproof Tottll - Fully sealed SPST toggle for low voltage applications. 15V DC 10A ritl111. Cat S-1195 $8.95 St1nd1nl OPDT Cetll11 Off - This switch features heavy duty contact rating. Makes ideal motor reversing switch, eg electric aerial on cars. 125VAC10ACatS-1217 $2.50 DSE 20MHz Dual Trace CRO You probably already know the value of a good CAO, and you won't find one of better value than this! Professional quality with outstanding performance and features that you just wouldn't expect a1 the price. Check it out • inbuilt component checker for capacitors, inductors, transistors, diodes, zeners, etc. • 20MHz bandwidth (-3dB) • Use in single or dual trace mode • Complete with 2 probe sets • Dual trace in chopped or alt mode and more! Cat Q-1260 5 899 ------------------ Beating an intermittent It is not often that an intermittent fault can be regarded as predictable. Which is one of the reasons we hate them; they waste a lot of time but seldom teach anything. Well this month's story is different - I've had four so far and, after the first one, they were a snack. Perhaps I'm stretching things a little to imply that these were true intermittents, but they did exhibit the characteristic that sometimes they would work and sometimes they wouldn't. So as far as the customer was concerned, they were just that. What's more, it was serious enough to fool at least one professional service organisation. The story started with a call from the local video store proprietor. As well as video cassettes, they stock a range of video recorders and players for rental, and I service these units. In this case the ·device was a Rank Arena VCR, model RV340, and the complaint was that it would not rewind or fast forward. No mention was made of any other fault and I suspect that this was because it was seldom used in a situation where the fault would show. In fact, it was used mainly in the shop to check or display cassettes, rather than for rental. (It ultimately transpired that this machine was marketed under at least four labels. As well as the Rank label it appeared as the JVC model HR7200EA, which is the origin of the beast, as General Electric GE V6900, and as Ferguson 3V29A Ferguson being associated with EMI-Thorn in the UK.) I was at a disadvantage with this machine in that I had not encountered it before, and had no manual for it. On the other hand most machines are broadly similar and I felt reasonably confident about tackling it on the basis that it was probably a fairly straightforward fault. Time enough to worry about a manual if the fault turned nasty. I'm not sure how old this particular machine was, but I would suspect at least five years. It was a top loading type and probably among the last of these before the front loading types appeared. Initial checks I pulled the cover off, checked for any obvious faults, like foreign objects or mechanical damage, then loaded a tape into it to see what would happen. The machine accepted the tape and when I pressed the play button, it began to play. The only snag was that the takeup spool was not being driven and tape began to build up as it came away from the drum. I hit the stop button before the automatic shut- J;IGH~1 54 SILICON CHIP down functioned, then tried to make the machine wind the surplus tape back into the cassette. It wouldn't, which more or less tallied with the owner's complaint. My first reaction was that this machine looked very like a Sharp and, based on experience with the Sharp, I suspected the tyre on the idler wheel; the wheel which is driven by the reel motor and which toggles between driving the supply reel disc and the take-up reel disc. When the tyres deteriorate they no longer provide the necessary drive to these discs. I had some spare tyres on hand and it wasn't a big job to fit a new one. Then I tried the tape again, only this time I simply checked for forward and rewind functions. Neither operated and I realised that I had a more serious fault. The most likely explanation now was that the reel motor was not running, but confirming this was not as easy as might be imagined. The idler wheel is driven directly from the motor shaft and this is quite small, precisely ground, and revolves at high speed. It is also difficult to see. I tested it by touching the blade of a screwdriver against it and feeling for vibration. There was none. Dead reel motor So was it a faulty reel motor, or a faulty circuit robbing it of drive voltage? Clarifying this involved inverting the machine and removing the approriate covers. Then it was a short step to establishing that, yes, the reel motor had "had it" . Reel motors aren't cheap; they can range from $40 to $100 according to make, so I conferred with the owner. He didn't hesitate and said go ahead. From there on it was routine: order the motor, give the machine a routine clean, drum, heads, etc while waiting, then fit the new motor and give it a test run. It came through with flying colours and produced a first class picture. But rather than accept it on the basis of a few minutes performance I decided to give it a long test run. I had no particular reason to do this, other than the fact that the owner wasn't in a hurry and I had a spare monitor available. And so it ran for several hours, and it performed perfectly. Then I turned it off, mainly because I needed the power point. And this is most important: the machine was turned off at the power point rather than by its own on-off switch, which would have left it in the standby condition, with clock running. Some time later I gave the machine another run, a shorter one this time, and again it performed perfectly. But when I switched it off this time, I left it in the power point with power on, switched off at the machine, the clock running and everything ready to go. TETIA CORNER Sony KV1800-AS Symptom: No sound or picture. 11 0V rail up to 135V. There is no line drive out of the "D" board but the set will run normally if the line oscillator is powered momentarily from an auxiliary supply. Cure: C531, a 1 0µ,F 160V electrolytic capacitor , open circuit or dried out. At switch on, this capacitor charges from the 11 0V rail and feeds a momentary burst of power into the 18V rail. This starts the line oscillator after which the line output stage supplies the normal 18V rail. It sat like this for a couple of hours, then I decided to play it again, not so much as a test but because I had a tape I genuinely wanted to play and check. And this was where things went wrong. The machine went through the loading procedure - ie, wrapped the tape around the drum - but after a moment, shut itself down. I went through the exercise a couple more times but with the same result. So there was nothing for it but to pull the top cover off, load the tape in once again, and try to see what was malfunctioning. It wasn't hard to find. The machine loaded the tape around the drum correctly, started the drum motor, and was all ready to play except for one thing: the pinch roller had not closed on the capstan. As a result. the reel motor did not start and the machine, sensing that something was wrong, shut down. Two step pinch roller I went through the exercise again and observed the pinch roller action more closely. It actually moves in two steps, starting some distance away from the capstan and making its first move as the tape is being loaded but stopping slightly short of engaging the tape and capstan. Then, when the tape is fully loaded, A l'llll. "1988 55 it moves into contact with the capstan. Or that was what was supposed to happen. In reality, it baulked at that last movement. And, incidentally, that final movement signals other functions, such as the reel motor operation, to commence. This was a serious setback. I had seen enough of the mechanical setup, plus the electrical system as represented by innumerable cables, plugs and sockets and solenoids to realise that this was no job to tackle without a manual. I rang the owner, explained that we had a second fault, and asked a few discreet questions to try to confirm a theory I was nurturing. The result was inconclusive, although he recalled that it had failed to operate on odd occasions and, yes, this could have been in the circumstances I suggested. Hot theory Well, at least he hadn't shot down my theory. Whatever it was, I suspected that the fault was temperature conscious. If the machine was plugged in cold and a tape loaded immediately it would play it for as long as it lasted - up to four hours. But remove the tape and try to play another one and the machine's internally generated heat would prevent it. Similarly, if the machine was simply left for a time in standby mode, its own internal heat would then stop it playing a tape. As used in the video shop it was seldom plugged in until needed, so the fault had gone unnoticed except for a few occasions when it had been left on. And since it came good the next time, it was not of much concern. I went on to explain to the owner that I feared it was going to be a difficult job, aggravated by the fact that I didn't have a manual. This latter now appeared to be essential and I wasn't sure I could get one. Obtaining a manual was complicated by the fact that I was still under the impression that it was a Rank machine. It was only during a visit by a rep. from a parts distribution firm that I learned its real origin - JVC. More to the point he said he was sure he could get one, but warned that it could take time 56 SILICON CHIP I F\N\~~EP U? Wrn-\ ~E T\>JO IV\~C. \·H ~E.S 'S'rR \'?~ED l'l P...~ ED; CS\~~'<- S\DE. ON \r\~ "BE~C..~.. · and would be fairly pricey, which is par for the course for these manuals. I told him to go ahead. And he was as good as his word - in more ways than one. He obtained a manual, but it took over three months and it cost $65. I didn't qibble over the price. As I said before, that kind of figure is typical for such manuals, but I do wonder if the general public realise the kind of "incidental" costs like these that a serviceman has to meet. I'd hate to speculate on the capital cost represented by the stack of manuals in my workshop; costs which must ultimately be passed on to the customer. On the bright side was the fact that it turned out to be a first class manual; very comprehensive and virtually devoid of Japanese English. And that's a plus in anybody's book. Back to the fray So back to the problem, which was pretty confusing. The fact is that the inside any video recorder is the most complex arrangement of levers, cams, gears, belts, pulleys, clutches, springs, shafts and pushrods that anyone can imagine. Add to this sundry switches, plus the occasional photocell and exciter lamp, and you have a combination against which Heath Robinson's collections of strings, springs, weights, and lighted candles pales into insignificance. More to the point, one can never be sure, initially, whether a particular pushrod is pushing an adjacent lever, or being pushed by it. It's all very complicated. The obvious place to start was with the malfunctioning pinch roller. This is operated by the pinch solenoid which is controlled by two transistors, Q4 and Q5. It is an unusual arrangement in that Q4 feeds the whole of the solenoid winding, while Q5 feeds a tapping. My initial reaction was that this was a way of providing the dual action of the pinch roller, as previously noted. In fact I was wrong. The first movement of the pinch roller is purely mechanical and only the final, shorter movement is enabled by the solenoid. (I will deal with the reason for the two transistor arrangement later.) But this was of little consequence. The important point was that the roller was not operating for the simple reason that the solenoid was not being activated. There followed a long and involved chase through both the circuit and the machine to find out why. This was prolonged by the need to set up the hot and cold conditions needed for "fail" or "perform" behaviour. I won't bore you with the details. Suffice it to say that I cleared the ,,,i.., ,"r1, I / I 1/ f I I r1 I I I '7"1 ® / / I f'\1, I I I t:.J L--v / / / Loading motor-++--~' \ Capstan motor Capstan belt ------ Capstan flywheel '-- Capstan Take-up clutch belt Take-up clutch Take -up idler Take-up reel disk / Supply reel disk Reel idler Reel motor Reel idler Fig.1: general layout of the video recorder, with the loading motor and associated gearing shown dotted in the top left corner. The pinch roller (not shown) is adjacent to the capstan. transistors and finally established that they were supposed to get a signal from what is called the "after-loading switch"; (AL) SW S002 on the circuit. So I had to find this device and more importantly, what was supposed to activate it. To tell the truth, I never did lay eyes on it. Its location is indicated on some of the drawings, but it is totally hidden by other components. To replace it would probably mean stripping down most of the deck. Faulty twins At this point I put the machine aside, partly to give myself time to think, and partly to attend to more urgent jobs, the owner having indicated he was not in a hurry. So it sat on the bench for a couple of weeks, until, in fact, another customer appeared with the GE version of this machine. His was a long tale of woe but, in essence, it boiled down to exactly the same symptoms as the Rank. So now I had two nasties to deal with. Which meant two failures if I didn't crack it, or two service fees for the one effort if I did. (That's how servicemen think!) I finished up with the two machines stripped naked, side by side on the bench. After a number of test runs I confirmed that both not only had the same symptoms but that behaved in exactly the same way in regard to the pinch roller. So it really was the same fault. So what now'? I was still trying to work out what activated the after loading switch and, after numerous tests in both the fault and no-fault condition, I latched onto a particular lever. I think it is called the pinch roller arm push plate and is shown as ·having one end in the area of the after loading switch, with the other end attached to a spring in close proximity to the pinch roller arm. It is made with two slotted holes which fit over two studs, and it moves back and forth for the length of these openings during the loading and unloading sequences. (I later concluded that it provides the initial movement of the pinch roller.) I picked on it partly because of its proximity to the after loading switch and partly because I noted that, in the no-fault situation, it moved over the full length of the slotted holes but, in the fault condition, only part of the way. In an effort to clarify things I set up a fault condition, then pushed it gently the rest of the way when it baulked. The pinch roller snapped home immediately and the machine played, but the picture was poor / \I'll/I. Hlll8 57 loading ring was obviously what activated the after loading switch, it was clear why the system failed. I was able to prove this by gently prodding the loading ring the remaining distance when it baulked. Everything came good immediately and the machine produced a perfect picture. . . : Unloading c>: Loading Slack belts Wormwheel gear Worm gear Take-up loading ring Loading motor Loading belt Fig.2: exploded drawing of the loading rings, driving gears, and loading motor. Note the direction of rotation. due to an apparent tracking problem. VCR revision To follow the story from this point the reader will need to have some idea of how the loading mechanism works in a typical VCR. When the cassette is inserted it is located over the two reel discs (supply and take-up) with the tape in front of two guide rollers. The protective cover of the cassette is then opened and the two guide rollers then move away from the cassette, one each side of the head drum, drawing the tape with them and wrapping it around the drum for a little over half its circumference. It was the mechanism associated with these guide rollers which took my attention next, and their operation is most easily explained by Figs.l, 2 and 3 taken from the manual. The guide rollers are moved by two loading concentric rings which rotate in opposite directions. These are driven by the loading motor, via a wormwheel and a gear train which drives the upper ring directly, and the lower one via a relay gear to provide the reverse direction. 58 SILICON CHIP As shown in Fig.3 the guide roller assembly sits above the slide ring which, in turn, sits over the loading ring, being coupled to it via a spring. Now notice particularly the slotted holes in the slide ring, and the pins on the loading ring which sit inside them. During the loading operation, with the upper ring rotating clockwise, these pins would occupy the positions shown, until the guide roller assembly reached the end of its travel as dictated by stops called pole guides. At this point the loading ring(s) would continue to rotate until the pins reached the other end of the slotted holes, thus putting the spring under extra tension and driving the guide roller assembly hard against the pole guides. This is to ensure that the guide rollers remain rigid and hold the tape accurately against the drum. Failure to do so can cause tracking errors - as I observed when trying to brute-force the system. At least that was what was supposed to happen. What was really happening, under fault conditions, was that the pins moved only about two thirds the way along the slots. And since this final movement of the But why was the system baulking? Putting it through the loading process a couple more times, in fault condition, produced the answer. The loading motor . continued to run briefly after the system baulked, with the belt simply slipping on the pulley. A little extra tension on the belt, artificially applied, cured the problem, albeit temporarily. I suspected the belt was the culprit, either worn or aged. Starting with the Rank, I pulled th~ belt out, along with the other two; the capstan belt and the take-up clutch belt. All three were in poor condition and needed replacing, even though the other two had not given trouble. Since I had none in stock I put several sets on order. Incidentally, the loading belt is the hardest one to get out. The only way to get it out is to remove the complete loading motor assembly, which is relatively simple, involving only two screws. Then a circlip is removed from the end of the worm gear to allow the shaft to slide out and release the belt. It is easy enough to fit the new belt to the motor assembly while it is out of the machine, and easy enough to slip the assembly back into place. But unless the correct associated procedure is followed the machine will not function. There is not much in the manual covering this operation and I finished up doing it on a suck-it-and-see basis. In fact the procedure is simple enough in theory but, in practice, needs about four hands. All that is needed is to pull both guide roller assemblies hard back against their stops in the unloaded position, and hold them there while the loading motor assembly is slipped into place and the two securing screws fitted. I won't try to explain how I did it with only two hands! Slant pole Guide ro ller Supply pole base €,; 0 Supply loading ring Pin I ' slide ring Fig.3: detailed drawing showing the supply slide ring (note tension spring) and the guide roller assembly driven by it. Next I tackled the GE machine. The situation here was the same; a faulty loading belt. But the interesting thing was that the other two belts were brand new, having obviously been replaced during a recent service. But why had the real culprit not been replaced? Too hard I suppose. Naturally, after the battle with the Rank, the GE machine was all plain sailing, and I had it up and running in short order. Which helped make up for some of the time expended on the Rank. Since then I have encountered two more machines with the same fault, which has put the balance sheet for this episode back in the black. Post mortem But there are some points still to be clarified. The most important one is the reason for the thermal sensitivity of these machines when the loading belts deteriorate. My first reaction was to assume that the elasticity or size of the belt changed with the temperature. On reflection, however, I'm inclined to reject that theory. I don't believe that the temperature change was great enough to affect the belt material in this way. I'm more inclined to the theory that it is metal expansion that is involved; that somewhere the tolerances on some metal parts are just too fine. This is not evident while the loading belt can provide adequate drive, but shows up when the latter begins to wear. Unfortunately, I can't be sure either way. Next point: why does the pinch roller solenoid employ two transistors and a tapped winding? It ap- pears that the solenoid needs more pull to snap the pinch roller into place than is desirable when it is in operation. So Q4, which feeds the full winding, is turned on the whole time the machine is playing. Q5, which feeds the tap, receives only a 330ms pulse at the moment the solenoid is turned on, to boost the action. And that about sums it all up. It has been a long story, but I think a detailed explanation was justified. So keep an eye open for these machines and these symptoms. My experience could save you a lot of time and headaches. (Since this story was written the Serviceman has reported that another three similiar jobs have come in for repair so it looks like it will be a common fault. Ed). that this MHA was installed when television was introduced in southern Tasmania in 1960. Since then it has worked - and worked - and worked. I was able to help in regard to locating a new 6ES8 and this put the MHA back in working order again, hopefully for another 27 years. Out of curiosity I dug out my old valve manual from under a pile of forgotten literature and looked up the 6ES8. It was a variable-mu twin triode RF amplifier designed for series operation in TV tuners. In this mode it required a supply of 180V, together with 6.3V for the heater, and a variable negative AGC voltage. I did not see this antique MHA, so I can't be sure how these voltages were supplied. My guess is that there was a 240V feed up the mast to a transformer and solid state rectifier. (Yes, power diodes were available in the 60s.) The RF output was on 3000 open wire feeder continued on page 90 j) Back to valves To finish off, here is something in lighter vein from our colleague, J.L., of Tasmania. He writes: I had a call recently from a colleague in a bush town about 80km south of here. He asked if, by chance, I had a 6ES8. Now I have to admit that I asked him to say that again while I put my brain into gear. I haven't heard type mumbers like 6ESB for so long that I have almost forgotten what they mean. Then I recalled that these were common RF amplifier valves in 1960 model TV sets. I quizzed my friend as to why he was messing around with these old sets. It transpired that he was not servicing a TV set at all, but a mast head amplifier. He went on to say ,~CHNlC.lAN TR't'\NG ro GE", :Be.L,.°\"S ON o.. 1\i'HIL UJ/l/l 59 Forget about messy chemicals for pH checks A pH meter for • • g pools If you hove o swimming pool you will wont to measure the water's pH from time to time to ensure healthy water condition. This new pH meter is much cheaper than previous instruments. By JOHN CLARKE & LEO SIMPSON Years ago, pH probes were virtually a laboratory curiosity but they are now finding use in the home for monitoring the swimming pool and fish tanks, and in gardening. Perhaps the most obvious use is in monitoring the family swimming pool to help combat the dreaded scrurge of all pools - algae. To prevent the growth of algae and kill all those nasties such as E. coli, proteus and giardia, chlorine is added to the water. This can't be done indiscriminately though because the pH of the water must be kept within A small plastic case houses the low-cost electronic circuitry. The pH probe is supplied complete with buffer solutions which are needed for calibration. 60 SILICON CHIP fairly narrow limits, between 7.2 and 7.6, for the chlorine to work effectively. If you keep marine or tropical fish, the pH of the tank water is a very important consideration, if the fish are to survive and thrive. Similarly, if you're a keen gardener, you will know that many plants require acid or alkaline soils to do best. If you have a pH meter, you can keep a close check on soil conditions. Soil pH can be measured by mixing 10 grams of soil in 100ml of water and then measuring the pH of the resulting solution. The pH probe Previously, pH probes have been very expensive and used fragile glass construction. This new pH probe has a body made of clear polypropylene and a 'spear' shaped membrane (the 'business' part of the probe) which allows easy cleaning with a cotton bud. The probe is suitable for measuring solutions with a pH range from zero to 14 and has a reasonably quick measurement response time, to 98 % of ultimate reading, within 20 seconds. The probe is supplied complete with buffer solutions which are needed for calibration. As soon as we became aware of this new probe we were enthusiastic about the possibilities for an economical pH probe. We decided on an analog meter which could be driven by a few op amps. The result is as you see it; a compact instrument using just two integrated circuits, one three terminal regulator and three pots. That makes it all seem very easy but the design was no pushover 3.9k +5V VR4 10k 2.2k 14 TP2 ------<Asv~rlTRY 1k POWER ~ T 9V : ...L. OUT 10 16VWJ -=t +5V + 2.2 16VW! -~M pH METER GND T SC4-2-488 Fig.2: the op amps all operate as voltage followers. ICl provides a high input impedance to match the probe, while IC2a, 2b & 2d buffer the slope, temperature and asymmetry controls. IC2c provides a + 2V reference voltage. 60D 500 400 "' r---... ........ ~~ 3D0 "'o~ ~'oo"c 200 100 -100 "' ~~ ~ ~ ' ~~ ~ ~ ::--.... --~ ~ ..... -200 -300 "' - 400 -500 r--...--.........:: ---....... ~... "- -600 0 10 11 12 13 14 pH Fig.I: this graph shows the pH probe's output for three temperatures (0°C, 25°C and 100°C) over the full pH range from zero to 14. since pH probes have an output voltage which varies all over the place. They need compensation for three parameters: slope, temperature and asymmetry. Of these, temperature has the biggest effect on the probe. As well, a pH probe is a very high impedance device, around 200 to 500 megohms, so it needs a measuring circuit which can provide an extremely high input impedance. Let's have a look at how these parameters vary the pH probe's output and then we can see how the circuit provides compensation. Compensation Fig. 1 shows the variation in the pH probe's output for temperature extremes of 0°C and 100°C, over the full pH range of zero to 14. At a pH value of zero. the. probe output ranges from + 518mV at 100°C to + 379mV at 0°C. Similarly, for pH14. the probe output varies from - 518mV at 100°C to - 379mV at 0°C. Note that temperature variations have no effect on the pH probe's output at pH 7 and so therefore the characteristics show that the probe has an output of zero millivolts at this pH value. In fact though, this is not the case. Real probes can have an output anywhere between ± 50mV at a pH value of 7. Our circuit compensates for this " offset" voltage by providing an adjustable compensating voltage. This is varied by the Asymmetry control. Another variation in the probe's output is brought about by ageing. Typically, this can cause the output voltage to diminish down to about 94% of the output when new. Our circuit compensates for this ageing process with a "Slope" control. This can accommodate for a 15% reduction in output due to ageing. Circuit description The circuitry of the pH meter uses one quad op amp package and one single op amp package, three potentiometers and a few other passive components. ICl is the single op amp package, a CA3130 Mosfet input op amp which is used as a unity gain voltage follower. This provides the extremely high input impedance of one Teraohm, or one million megohms. So high is this impedance Al'll/1 , 1088 61 ~ pHPRO~E INPU~ / 10 9 Fig.3: the PCB has been designed to fit the meter terminals. The pH probe cable may either be soldered direct to the PCB or connected via a BNC socket as shown. Install PC stakes at the two test points, TPl and TP2. that even the smallest leakage and capacitance effects can degrade it. These effects are minimised on the printed circuit board by a "guard ring" which is connected to the op amp output, via a 3.9k0 resistor. This effectively negates leakage effects. The output of ICl feeds VR2 and a series 5.6k0 resistor. VR2 is the Slope control, referred to previous- ly. Following VR2 is another voltage follower stage, IC2a, but this time it's an ordinary op amp, one of an LM324 quad op amp IC. IC2a's output is fed to a voltage divider comprising 3.9k0 and 6.Bkn resistors in parallel and a lk0 resistor in parallel with a lOk0 potentiometer, VR3. VR3 provides the correction for temperature variations in the measured solution. IC2b is yet another voltage follower , for the output of VR3. When you look at the rest of the circuit, you'll realise that all five op amps are connected as voltage followers or, to put it another way, as non-inverting unity gain buffers. IC2b drives the negative side of the meter movement. On the other side of the circuit, VR5 allows adjustment to compensate for the probe offset referred to earlier. VR5 is the Asymmetry control. Its output is buffered by IC2d which drives the positive side of the meter movement. Now comes the clever bit. Note that the "ground" side of the input socket and negative connection for the 5.6kn, 3.9k0 and 6.Bkn resistors is not the negative rail for the whole circuit. Instead these points are connected to the output, pin 8, of IC2c. IC2c is used to provide a + 2V voltage reference for the pH probe and the slope and temperature dividers. The output nominally sits at 2V by virtue of the voltage divider at the non-inverting input, pin 10, of IC2c. So the four op amps of IC2 and the associated offset and the resistor networks associated with VR2 , VR3 and VR5 all provide compensation for the probe so that it reads pH correctly. VR4 sets the meter current for full scale deflection and VRl provides offset voltage compensation for ICl. So there it is, a simple but clever circuit. It allows a rather intrac- t;~ ~----------- tt«n SC 4-2-488 OO At left is a view inside the prototype while above is an actual size artwork for the PCB. 62 SILICON CHIP the lid of the case, the printed board can be mounted on the meter terminals. Two solder lugs, which are supplied with the meter, can be soldered in place over the meter terminal holes on the board. The board is then secured using the nuts on the meter terminals. The photos show how we did it. We used short lengths of rainbow cable to connect the pots and the switch to the respective points on the printed circuit board. The probe cable The two solder lugs supplied with the meter should be soldered in place over the meter holes on the PCB. The board is then secured on the back of the meter using the two meter screws. table extremely high impedance device, the pH probe, to drive a 50µA meter and yet provides quite a lot of tricky compensation. The circuit does all that without providing any voltage gain and does it with two common IC packages, the CA3140 and the LM324 . As a bonus, the LM324 is not only·cheap, but is ideal for battery-operated circuits since its current drain is typically only 800 microamps, or only one milliwatt per op amp, at 5V. The pH meter is ideal for checking swimming pools but can also be used to check fish tanks and soil acidity. Wash the probe and replace the plastic cap after use. The 5V supply rail for the circuit is derived from a 9V battery using a 7805 3-terminal regulator. The regulator is critical since any change in the supply voltage will alter the offset voltage of the op amps and thus degrade the compensation provided. Construction Our pH meter was built into a standard plastic utility box, with plastic lid, measuring 130 x 68 x 44mm. We designed a printed board to suit the case and to fit onto the terminals of a standard MU-45 50µA meter movement. We do not recommend the use of Veroboard for this project, as the layout is critical, especially the guard ring for the CA3140. Our printed board measures 76 x 58mm and is coded SC4-2-488. Befo,re mounting any components on the board, make sure that it will fit onto the terminals of the meter. Make any adjustments to the mounting holes at this stage. Mounting the components is straightforward. Just follow the wiring diagram. When the board is complete, the case must be worked on. If you have purchased a kit, it is likely that it will come with a ready-drilled and silk-screened case. If not, you will need to make and attach a Scotchcal panel to the lid and then make the cut-out for the meter and drill holes for the three potentiometers and the on/off switch. When the meter is mounted on That done, a BNC socket needs to mounted on one end of the case and a connection made from it to the printed board. Don't use ordinary shielded cable for this job; it is not suitable. You can use a short length of RG58 coax cable or, as we did, a short length of the ea ble from the probe itself. PARTS LIST 1 plastic case, 130 x 68 x 44mm 1 PCB, SC 4-2-488, 76 x 58mm 1 lonode pH probe (G101 NFE) with pH 4.00 and pH 6 .88 buffers 1 front panel artwork 1 side panel artwork 1 meter scale artwork 1 MU-45 50µA meter 1 SPDT miniature toggle switch 1 panel mount BNC socket 1 line BNC plug 1 91 6 9V battery 1 9V battery clip 3 knobs Semiconductors 1 7805 5V 3-terminal regulator 1 CA3140 FET input op amp 1 LM324 low power quad op amp Capacitors 1 1OµF 16VW PC electrolytic 2 2. 2µF 1 6VW PC electrolytic Resistors (0.25W, 5%) 1 x 6.8k0, 1 x 5.6k0, 2 X 3 .9k0, 2 x 2.2k0, 1 X 1k0, 1 X 100k0 miniature vertical trimpot, 1 x 1 Okn miniature vertical trimpot, 1 x 1OkO linear potentiometer, 2 x 1 kn linear potentiometer Miscellaneous Rainbow cable, grommet, solder. A l'!l/L 1988 63 I- OFF O ON 'f!l::ilff& 1L'JLti/l/;-l;! pH METER SLOPE ASYMMETRY A A 100% 40 50 60 30~70 J__: 20 10 0 oc 80 90 100 :-l Above are actual size artworks for the front and side panels. The probe cable must have a BNC plug fitted to it. Ideally, it should be a crimped BNC plug but few readers will have the facilities to do that. The alternative is to use an ordinary BNC plug but the thin cable from the probe needs to be have an insulation sleeve to build its thickness out to the 7.5mm diameter needed to mate properly with the plug. Another alternative is to solder the probe cable directly to the board and forget about BNC connectors altogether. The ea ble should be passed through a small grommetted hole in the end of the case and clamped before being terminated to the board. This is electrically satisfactory but makes it less easy to store the probe safely in its plastic case. Remember that, even though this pH probe is made of plastic, it is still a relatively fragile instrument which should be treated with care. 64 SILICON CIIII' Calibration Initial setting up of the pH Meter should be done firstly by shorting the pH probe input and adjusting the input offset of ICl. Now connect a multimeter set to read DC millivolts between the output of ICl and the output of ICZc. Adjust trimpot VRl until a reading of 0mV is obtained on the meter. 0 0 This meter artwork is designed to fit an MU-45 50µA meter movement. Set the VRZ Slope control to the 100% position and the Temperature control to the 100°C setting. Connect the multimeter between test points TPl and TPZ (positive lead to TPZ) and adjust the Asymmetry pot VR5 for a reading of + 320mV. Then adjust trimpot VR4 so that the pH meter itself reads pH 7 or centre scale. Calibration requires two buffer solutions, one very close to pH 7 and another several units away from pH 7. The Ionode pH probe is supplied with two bottles of buffer solution, one a phosphate buffer of pH 6.88 and the other a phthalate buffer of pH 4.00. (Buffers are solutions of known pH which can absorb large quantities of contaminants with little change to the pH value). Note that the pH probe comes with a protective cap. This cap must be carefully removed before the probe is used and replaced when you are finished. The cap physically protects the probe from damage and slows down any drying out of the probe memebrane. To start calibration, set the Temperature control to match that of the buffer solution. Set the Slope control to 100%. Place the probe into the 6.88 buffer and adjust the Symmetry control until the meter reads 6.88. Leave the probe in the solution for several minutes to check for drift and reset the Asymmetry control if necessary. Remove the probe and wash the membrane in distilled water. Then place the probe into the pH 4.00 buffer and use the Slope control to obtain the correct reading. Now wash the probe again and place it in the pH 6.88 buffer. Adjust the Asymmetry control for the correct reading, then wash the probe again and repeat the process for the ph 4.00 buffer. This procedure may need to be repeated several times to correctly calibrate the unit. This is because the asymmetry and slope are not known. If pH readings are being taken regularly, say every few days or so, then it won't be necesary to calibrate before each use. If used less frequently though, you should go through the calibration process to ensure accuracy. ~ .,. -WE INVITE BECOME THE ELECTRONICS MAGAZINE FOR THE ENTHUSIAST You To A SUPPORTER We believe that electronics is a fascinating pu:rsuit, and the most useful hobby that anyone can have, particularly for a young person in school. Anyone with a good grounding in electronics is better prepared to meet the challenge of today's and tomorrow's technology. Because we believed that many more people should come to know about and enjoy electronics, we decided to start a new magazine expressly for electronics enthusiasts, whether they be nervous beginners or seasoned veterans. We called it SILICON CHIP, a name which focuses on the very basis of today's electronics technology. We started SILICON CHIP as an independent magazine completely free from the influence of any existing publishing company, because we wanted to establish the highest possible standards for accuracy and attention to detail. Our team is very small: founders Leo Simpson and Greg Swain, plus full time staff members John Clarke and Bob Flynn. SILICON CHIP has now been on sale for five months and has been very well received. Even at this early stage, you, the readers, have clearly indicated that SILICON CHIP is the most entertaining and best produced electronics magazine in Australia. Considering the hard work in getting started, it has been a very gratifying response. But we want to make SILICON CHIP even better. To do this, we need the resources to employ more people; we need the services of technical illustrators, writers, designers and other creative people. This is the only way that we can be S\].re of attaining the highest possible editorial standard. We know this is what you want. Your letters tell us. But we can only do this with your enthusiastic support. Already, many hundreds of readers have taken out subscriptions to give SILICON CHIP a solid start but we we would like to have thousands more. If you haven't already done so, please give us your vote by becoming a subscriber. By doing so, you will be ensuring the future of an entertaining, informative and independent SILICON CHIP magazine. Regular Features * * * * * Constructional Projects For The Enthusiast · HiFi Review Digital Electronics Course Circuit Notebook Vintage Radio Junk Mail * * * ·* The Serviceman's Log Amateur Radio, by Garry Cratt, VK2YBX The Way I See It, by Neville Willams Book Reviews Most magazines sell their subscriber list to mail order companies, to earn extra income. We will not do this. We will lose some money by adopting this policy but we believe that your privacy is paramount. BECOME A SUPPORTER BY FILLING OUT THE POSTAGE FREE SUBSCRIPTION COUPON OVERLEAF ► APRIL 1988 65 FREEPOST SUBSCRIPTION COUPON BACK ISSUES To: Freepost 25, Silicon Chip Publications, PO Box 139, Collaroy Beach, NSW 2097, Australia. NO POST AGE STAMP REQUIRED IN AUSTRALIA NAME (Mr/Mrs/Ms) ................................................................................... . STREET ......................................... ............................................................ .. SUBURB/TOWN ......................................... ...... ........... POSTCODE ............ . Subscription cost: 1 year (12 issues) 2 years (24 issues) Within Australia □ $42 □ $84 Overseas surface mail □ $62 □ $124 Overseas air mail □ $120 □ $240 Enclosed is my cheque or money order for$ ........... or please debit my D Bankcard D Visa Card No ..................................................................................................... .. Signature .................................................. Card expiry date ...... ./ ...... ./ ...... . Subscription to commence in .................................................................... .. GIFT 1 to: Issue Highlights NAME (Mr/Mrs/Ms).......................................................... ......................... . December 1987: 1 00W Power Amplifier Module; Passive lnfrared Sensor for Burglar Alarms; Universal Speed Control and Lamp Dimmer; 24V to 12V DC Converter. STREET ........... ...... ........................................................... .......................... . SUBURB/TOWN .......................................................... POSTCODE .. .......... . Subscription cost: 1 year (12 issues) 2 years (24 issues) Within Australia □ $42 □ $84 Overseas surface mail □ $62 □ $124 Overseas air mail □ $120 □ $240 Enclosed is my cheque or money order for$ ........... or please debit my D Bankcard D Visa January 1988: 4-Bay Bowtie UHF Antenna; Dual Tracking Power Supply; Custom Phone Ringer; Subcarrier Adapter for FM Tuners. Card No .............................................. ........................................................ . February 1988: 200 Watt Stereo Power Amplifier; Deluxe Car Burglar Alarm ; End of File Indicator for Modems; Simple Door Minder; Low Ohms Adapter for Multimeters. Signature .................................................. Card expiry date ...... ./ ....... / ..... .. Subscription to commence in .................................................................... .. GIFT 2 to: NAME (Mr/Mrs/Ms)................................................................................... . March 1988: Remote Switch for Car Alarms; Telephone Line Grabber; Low Cost Function Generator; Endless-Loop Tape Player. STREET ...................................................................................................... . SUBURB/TOWN ........... ............................... ... ............. POSTCODE ............ . Subscription cost: 1 year (12 issues) 2 years (24 issues) Within Australia □ $42 □ $84 Overseas surface mail □ $62 □ $124 Overseas air mail □ $120 □ $240 Enclosed is my cheque or money order for $ ........... or please debit my D Bankcard D Visa Price: $5.00 each (incl. p&p). Fill out the coupon on page 18 (or a photostat copy or letter) and send it to: Silicon Chip Publications, PO Box 139, Collaroy Beach, NSW 2097 . Card No ...................................................................................................... . Signature ....................................... ........... Card expiry date ...... ./ .. .... ./ ...... . Subscription to commence in .................................................................... .. Note: photocopy this coupon if you don't wish to cut the magazine, or include the relevant details in a letter. 66 SILIC:()N C/111' \/ LIMITED NUMBERS OF BACK ISSUES ARE AVAILABLE SO DON'T DELAY 0~ _ _ _ _ _ _ _ __ . AMATEUR RADIO By GARRY CRATT, VK2YBX Mobile antennas for VHF and UHF amateur operation Last month we looked at the general types of antennas available to the radio amateur, and the reasoning behind the selection of an antenna for a particular application. This month we look at some of the more useful VHF and UHF mobile antennas, and suggest some practical construction methods. The choice of a mobile antenna for VHF or UHF is dependent on several factors. As the frequency of operation increases, the capture area of the antenna decreases. This means that at VHF and UHF, higher gain antennas are required to overcome the smaller aperture of the antenna and the higher path loss at these frequencies compared with HF. Normally, increased gain means increased antenna size, and this can be a mounting nightmare. If we try to mount a large antenna as high as possible for best performance, there may be height restrictions when entering a garage. If we mount the antenna at a lower point on the vehicle, the radiation pattern may be distorted, causing loss of signal. Also large signal variations will be experienced as the vehicle moves, not only due to obstacles in the signal path, but also due to the tilt of the vehicle as it is driven over terrain that is not perfectly flat. As explained last month, whilst the benefit of using an antenna with a Photo 1: the loading coil for the VHF 1/2-wave whip antenna, together with the 20mm-diameter PVC housing and metal end fittings. The whip section is screwed directly onto the top fitting at right. low angle of radiation can be realised over flat terrain, this low angle of radiation can be a distinct disadvantage when traversing hilly terrain. It is this dilemma which forces the amateur to compromise and use an antenna that has reasonable gain in the right direction, a usable angle of radiation in most conditions, and reasonable physical size. Practical antennas There are, however, a number of mobile antennas that do provide reasonable performance within the limitations discussed above. The 1/4-wave whip can provide up to ldBd of gain if it is mounted in the centre of the roof. At VHF, the 1/4-wave whip balances simplicity and reasonable size (49cm], against meduim aperture and a tendency to have a medium angle of radiation. It provides quite useful performance provided a good groundplane is Photo 2: both ends of the loading coil for the 5/8-wavelength antenna are soldered to the metal end fittings. The bottom metal fitting, shown at right, allows the completed coil assembly to be screwed into a standard TPI base. Al'lllL '1988 67 7 I en e .li "' N 9 TURNS, 1.6mm COPPER WIRE, 9.5mm INSIDE DIAMETER -..._ son COAX son COAX Fig.1: internal construction of the VHF 1/2-wave antenna. The coaxial cable enters through the end fitting and its centre conductor soldered to a short length of teflon wire which is then wrapped a:round the top of the loading coil. Fig.2: internal construction of the UHF 1/2wavelength antenna. Keep the lead length between the top of the loading coil and the bottom of the whip as short as possible (it's shown exaggerated here) and tune the antenna after installation with a GDO. available and it is mounted as high as possible. ½-wave whip The difference between mounting an antenna in the centre of the roof and on the rear guard or boot of a vehicle can be as much as 3dB! A logical progression from the 1/4-wave whip is the 1/2-wave whip which, when mounted on a minimal groundplane, has a high input impedance. If the radiator is extended to 3/4 of a wavelength, the impedance closely matches 50 ohms, but the radiation pattern is compromised. At about 0.6 of a wavelength, maximum forward gain is achieved. The solutions to both problems provide us with two usable antenna types. 68 SIUCON C/111' Photo 3: the completed VHF (left) and UHF 1/2-wave loading coils, prior to installation in the PVC housing. The end fittings may be secured using epoxy resin. At top is the completed UHF 1/2-wave antenna. LIST OF SUPPLIERS 26 TPI mounting base Mobile One Communications, PO Box 166, Randwick, 2035. Phone (02) 516 4500. Dick Smith Electronics, PO Box 321 , North Ryde , 2113 . Phone (02) 888 3200 . Santronic Corporation, PO Box 12, Kingsgrove, 2208. Phone (02) 758 1522. Half-wave coil fittings Space Electronics, Unit 1, 27 Garema Circuit, Kingsgrove, 2208. Phone (02) 758 2154 . Gutter grip mounting bracket Hatadi Electronics Corporation , 19 Wilmette Place, Mona Vale, 2103 . Phone (02) 997 7077. Santronic Corporation, PO Box 12, Kingsgrove, 2208 . Phone (02) 758 1522. Dick Smith Electronics, PO Box 321, North Ryde, 2113. Phone (02) 888 3200 . Captain Communications, 28 Parkes St, Parramatta, 2150. Phone (02) 633 4333. Standard Communications, 6 Frank St, Gladesville, 2111. Phone (02) 816 4755 . Stainless steel or fibreglass whip sections Mobile One Communications, PO Box 166, Randwick, 2035 . Phone (02) 516 4500. RF Industries, 7 4 Sydenham Rd, Marrickville, 2204 . Phone (02) 519 5188 . Polar Electronic Industries, 2 Commercial Rd, Highett, 3190. Phone (008) 33 5633. Loading coils If we add a series coil to the lower extremity of a 1/2-wave whip, ground the bottom end of the coil, and capacitively couple the feedline, the result will be an antenna having twice the gain of a 1/4-wave whip (twice the aperture), and which can be matched to a 50-ohm feedline. At VHF, the length of this arrangement (around 102cm) may be excessive, but at UHF it is quite manageable. The antenna requires only a minimal groundplane and so can be "guttergrip" mounted, eliminating the need for a hole to be drilled in the roof. A 3/4-wavelength whip provides the answer for those requiring an antenna with higher gain than a 1/4-wave whip, provided they are prepared to tolerate the increased length of such an antenna, particularly at VHF. We know that a 3/4-wavelength radiator can provide a close match to 50-ohm cable, but that the radiation pattern is not optimum for omnidirectional operation. If we reduce the length of the radiator by 1/Bth of a wavelength, and feed it with a coil equivalent to 1/Bth of a wavelength, we can produce an antenna having a close match to 50 ohms, a lower angle of radiation than a 1/4-wave whip, and gain approaching 4dB. So it is possible to design several antennas that can be used to overcome the physical limitations of vehicle mounting, and provide usable gain at VHF or UHF. Building your own Most amateurs will be familiar with the standard "Scalar" or "Belling-Lee" type antenna base, which utilises a 5/16th~inch diameter 26 TPI stud mounting system. These bases are made by many companies in Australia, and are used on almost all commercial 2-way radio installations. The base is normally fitted through the roof, or can be used on a metal gutter grip type bracket, allowing a variety of mounting positions. Photo 2 shows a metal fitting which can be used, together with a 6 TURNS. 1.6mm COPPER WIRE, 9.5mm INSIDE DIAMETER ~ Fig.3: internal construction of the 518th wavelength antenna. Both end of the loading coil are soldered to the metal end fittings and the completed assembly then screwed to a standard TPI base. length of 20mm diameter PVC conduit, to form an ideal base which is compatible with the standard 26 TPI base. This can be used to house the series coil for a 5/8-wavelength antenna, and simply screws onto the standard base (see Fig .1). The whip section can then be screwed directly onto the top of the series coil assembly. Construction of the 1/2-wavelength whip utilises a slightly different but equally inexpensive metal component, which allows easy mounting onto a gutter grip bracket. It also allows the coaxial cable to be fed inside the coil. There is a particularly clever method of capacitively feeding the coil. This involves soldering the centre conductor of the coaxial cable to a short length of teflon-covered wire, continued on page 96 Al'lll L 1988 69 Great Kit Projects To Build Many Just Released For 1988 Calling All Audio Purists This Great New Amp From Silicon Chip Is For You Power House 600W Inverter (See EA Dec'87) Go Anywhere 240V Mains Power rrom your car or truck battery with these fantastic DC to .AC Inverters A must for farming, camping, mining, boating, remote settlements and wherever else 240W power isn't available. Features: Strong custom steel chassis • Industrial grade power coat finish• Can be configured to operate off either 12Vand 24V DC• Very l_ittle internal wiring • Manual or Auto start facilities • Low battery cut out • Compact Toroid transformer. Fully Built & Tested K 6770 -KIT VERSION s425 K 6774 12V INPU T K 6775 24V INPUT s525 s525 Studio 200 Serles 100 Watts Per Channel Power Amplifier ri~1!;:J~~l~j;{i~f iJ!~tit~;!~a~a~~rg~d:!rT:i~;!~~~i~citors 1 1 ~_f ____[t_:_,r_;,_;_:;_}_'~-~_:'_i_i_;_;:_i_~__t_i_:!_~_~e-~;-~_::_ •_~_l_f_oi_:i_J_i_,~_y_•1_~_1_•[_?_:~_~_:_:_::_1.~_) ••••11111:11111:1! _:1 AC/ DC Millivolt Meter (See EA Dec'87) Precision measure crltlcol circuits Designed to cause minimal circuit . loading whilst reading very low level voltages. Features: AC/DC range • 7M Ohm input impedance• Reverse polarity indicator • Operates off 1 9V battery (not included) • 10mV to 30V ranges in 8 steps • Zero position • Battery Test position. K 2670 $ 55 .00 300 Watt Inverter With Auto Start Operates From 12V Car Battery Features: Auto start draws power from your battery only when appliance is plugged in and "turned on" i.e. battery can be left permanently connected if required. • Voltage regulated • Current Regulated • Current Overload unit self limits - Single PC Board construction - easy to build as there is very little internal wiring. Fully Built & Tested K 0155 s379.oo Car Alarm (See EA Aug'86) Ear Splitting 110db Modulated Tone (See EA Feb/Mar'88) New updated circuit incorporates facilities for testing transistor FETs and Zeners etc. Features: • Gain • Leakage • Breakdown Voltages • Zener Voltage • Polarity - NPN/PNP K 2527 s49 .95 Now our top selling Car Alarm. Two Sensor inputs-Normally open and normally closed enable simple connection to door, bonnet, Boot light~s~;;; es39 _95 S01!:.~~1~:1:on Controls the temperature of your ji :;:;:(;'.((\'.:'.\:... 7 ~!~~!~!e~:~EiJg~; 1~;:lefor1:11:1111111111:: :l:J\\\!:llll straight in, no need for modifications. (See EA Sept'86) K 6400 s39 .00 i{)( ••••• ...........................·. ............. ;:;:;:;::t::· i::::j ·.·..•· ..•............. Low Cost Dual Tracking Supply (See SC Jan'88) K 3325 ~~e ~=~ t~~ O Ideal For Experimenting & Prototyping with Memory, Logic & Op Amp. Features: Adjustable + or - 18.5V at 1. 7A• Volt Meter• Floating Ground • Doorout Indicator• Load Switch • Compact Sturdy "ABS" Instrument Case. s99 .oo I : ; ;r; i ;i~::~~;::~;:1;~~![ht~~:~~mae~~ \(~j~e;t shot for measuring heatsink temperatures, how hot it gets inside your i\\\11\lt:l\\:\~~I\\\I\\\\ '}iJW?X" .__ca•r•·•o•r•w•~-=_:h.se_:r_!_i~-t~-ec_~_:_~a_~_:r_Y_~_:o_sm•a•~-:O .. ve•~-~-g.C-to_ +_12_o_d_eg•.•c•._ _ _ _\:\j\\\l\llliii\:\'.'.,,, , congratulation• To The Design TearnAl s1111conChlP ax\netorlhl& ~!~ellen\Oes_ lgn K 2515 s299.oo 1GHz Digital Frequency Meter (See SC Nov'87 Jan'88) This superb 1GHz Frequency Meter wlll out perform many other lnItrumentI twice ltI price. Featurea: Professional machined and screen printed red perspex front panel • Easy to asemble and construct • No special tools required • Bright Hewlett Packard 8 digit display• Electronic switch latching • High performance IC's • High Quality Components. Capacitance Meter Adaptor \lil\1\il lil i\ !1\111 (See SC Nov'87) Great for hand selecting exact values e.g. exact values for timer circuits etc. 11 K 2520 T.V. Colour Bar and Pattern Generator (See EA Oct'87) Service Your Own TV & Save Dollars Ideally suited to T.V. repairs and amateur television production. Features: 8 patterns to choose from • PAL or NTSC compatible • Operates on Channel 1 • Horiz.ontal sync output • Vertical sync output • RF Output. Housed in rugged "ABS" instrument case. K 2100 s179.oo K 1400 S9.95 . (See EA Aug'BB) i ,-::,1•·•·: ,,.. ,::, Precision time your Procenlng \)\ ·:."):'/.'\ with this Low Coat Project :.':r•:, ' ::: .'.'::;:,,:: ~~~~i~:~~~r~~~\~r~i~o~~~:~IC i;::i:!:::il iiitr::::::: pr_ocessing from 1 second up to 9 :::-:,r.,Q(.\::,';',.,, minutes 59 seconds In 1 second ,,: ··.,,,,Qt,·•,;,:','· '"~~:::85.oo ii TeleJ ~~Jg~~~; ~ook It allows measurements up to 2.2uF Plugs directly into your meter via . in-built banana plugs. Suits Labtech Q 1075 s24 .99 Dlgltal Photo Timer \j i\ JiJJ\\i liiiii\ii;jii\\iii\j ~~g~f~~~bf~~i~A~~; 1: required for each phone . ')(]li/ ...... LowOhms Adaptor For Regenerative Radio (See EA Jan'BB) Step back in time and build this simple regenerative radio receiver. Using only 3 transistors, its not only fun to build , but uses Varicap tuning. K 1150 s55.25 Door Minder ::::::1 :::1::i:!!i!i! (See SC Feb'88) Large 7 Segment Display This project will sense a door opening in a large or small room and will sound a two-tone chime . It does not have to be anywhere near the doorway as it uses an ingenious sensor to detect the pressure change caused when thi, door opens. Ideal for use in shops, offices, doctors surgeries, Chemists etc. This large 153mm high seven segment display can be configured for use as either common anode or common cathode. Multiplexed on DC driver and arranged to have a decimal point on eitherthe left or right handside. K 1s1s s45.oo As we all knowit'sdifficulttoobtain accurate resistance measurements below50Ohmsorsowith conventional multimeters. This natty little adaptor plugs directly into your DMM via . in-built banana plugs enabling quite accurate measurements to50Milli Ohms and less. Full instructions provided . Ii ::;:::;:;.;,;:::;.·.;,:.;. .. . ': : \:/'. '/?, ;,; :. ·:·:.:::.:.:.:.;. .:,:,::,::;:::::;:::: .--------------------------------, I I I I Altronics Can Deliver Any Of The Quality Products To You Tomorrow Just Phone Your Order Toll Free 1 1 I On 008 999 007 I I I ~-------------------------------~ Dual Trace 20MHz Oscilloscope Thie all new CRO must be the best valued quality Oscllloscope In Australlal This new model is a 20MHz dual-trace Oscilloscope using a high brightness CRT with an illuminated scale. The vertical amplifiers have high sensitivity 1mV-5V/Div. The unit has LED's to indicate when the controls are in the 'uncal' postion, and to indicate if the trace has been triggered. The brilliant triggering circuit will trigger on just about any waveform applied . The highest triggering sweep is 0.2uSec/ Div. The Q 0120 also features a 'Hold Off' control for seeing the front end of the input wave form. Features: Large6" rectangularCRTwith internal graticule.• High sensitivity: 1mV/ Div. • High accuracy: +or-3% • Stable, low-drift design • 8 divisions of displayed dynamic range and accurated istortion-free waveform measurements• This instrument has a special TV sync separation circuit forquick measurements of video signals • A convenient X-Y operation mode allows phase difference measurements between two waveforms . Full 12 Months Warranty J w: [ 1 GHz Frequency Counter i•\§f•?• !~~t~:;~~~~~~]~::.i~!ii~r~f:s~Yir:/:~!!~uu~~~~~:~~1\~:~~~m brilliantly in the workshop, laboratory, university etc. 'WI Specification,: The pertinent specifications for the Model Q 1530 are ::1:,,,.,.,.,., ~~::.::~~;;:~a-Frequency Mea1urement1-Channal A• Range: 10Hzto 1OM Hz direct counter 1QMHzto 100MHz prescaled by 10 • Resolution: Direct counter: 1, 10, 100Hzswitchselectable-Prescaled: !111:::i:i:: w····· lz!(''.' .' ~~~~c~~~~i =-~~:~~s~ ~~~~~~ ~~l~it~~l~~o::csu~:i:: ~~::~~~~;itch Channel B- • Range: 100MHz to 1 GHz• Resolution : 100Hz, 1KHz, 10KHz switch selectale • Gate time: 0.027S , 0.27S, 2. 7Sswitch selectable •Accuracy: +/-1 count+/-timebaseerrorxfrequency. Period Mea1urement1(Channel 4)- • Range: 10Hz to 2.5MHz • Resolution: 10-7S, 10-Sswitchselectable•Accuracy:+/-1count+/-time base error x period. Totallze meaarement, (Channel A)• Range: 10Hz to 10HMz• Resolution: +/-1 count of input. General-• Display:8digits, 7mm •,.,1.:.•.:.,•,:,•.1,:,:,•.:,: •: .:, _ - .. ""' .• . · fO?. . . . •- ..... . ''"""""'""'' [~~~~1~~f~~i~~ftt~:~§Wk;fil)~(¥f f J~E; l,i o1530 s499.oo .,___ ~_~~-~_:_ie_~_~_:_-_:_i._1._~_gH•.C--+•6•0•d•e•g•.C••-H•u•m•id•i•ty•:•O•p•e•ra•t•in•g•:•10_-_9•0•%•R•H•·--"T---------- - - - - - - - - - - - - - - - - - 1 Audio Frequency Generator t't•?.ttt lw RF Signal Generator An RF signal generator is an absolute necessity when it comes to radio servicing . With provision for both internal and external modulation, this generator is a winner. Specifications: Freq.Range 100Kz150MHz in 6 Ranges RF Output Level 100mV RMS Accuracy +/-3% Modulatlon:- Internal (30% depth) 1KHz • External - 50Hz - 20KHz • Crystal Locked Oscillator Often in testing audio circuitry it is necessary to have an accurate and adjustable audio signal source available. This little generator even allows you to test 455 KHz IF stages Specification,: Freq.Range 10Hz 1MHz Accuracy +/-3% +2Hz Output Waveform, Sine/Square Output Level Sine : 8V RMS Square: 10V P-P Output Attenuator -20db, -40db and fine adjust. ]II::;: : :: 11 !11!11 1! 1 1\!\lil \li o1540 s249.oo :•:111111m1111n 1.am1i 11111:::•:111111111111.s:••::~1 ::111 1111:t. . . 1 ·~~: :~=~=~{=~t:rm~:~:r:::::::====:::=·=· 11 11 1 : •:••: :=:=:::::~===========:==== =·=·= =···········•-..•·.·.·.·.·.·.·.·.·.=-········...•.;-=-=== 1 1 : :=:t::::======•~=«===:=:=:=:=:======: =:=:=:;;:::::::=:===========::===:: ::::=====:::=====:=======~=:=~=~ =====:::=:=:=:=====:========:======:======:======:::=====:::=:========:=======:=============:•=·=· ·.·.·.·.•.·.•·•,•·!,\.l,!.•.:.:.••.••· 1 ·••; ! •i ! ........... ·,:,:,;.;:::::::;:;:;: 1 :-:;:::•···· ~===':':::Ii11■1.11ua111:::::lt111::Hllll::::::n111:11:11t:]l.ll:::::1.:11: J:: I:::::::::::f4...:~ ,:;:;:;:•,•,···· ....... . ·, .: :=: s ave''· o;e==~:=:ao6)~ ass s an Brake der Sealed Lead Acid Batteries These rugged high performance batteries are ideally suited for systems where uninterrupted DC Power is required i.e. Security Systems, Computers, Solar Power Systems etc. ossaas NOW Normally s80 Make Your Own Chassis Boxes, brackets,etc. Unique slotted upper clamping bar allows complex corner bends S 5065 12V/1 .2AH S 5067 12V/2.7AH S 5069 12V/4.5AH Clock Movement Fit your own custom clock face. Great for novel applications such as fitting to pictures etc. Very accurate, runs for approx. 1 year on one AA battery. Portable Multimeter With Bench Stand lncludee Continuity Buuer x 20,000 Ohms/Volt DC • 8,000 Ohms/Volts AC, Mirror backed scale• Overload protected, 10 amp DC current range. Unique carry handle doubles as a bench stand . 1010 s18.so New Model IRD Has lncludee Battery Tester Fantastic Range Free Carry Case This M onth Normally Q1080 $22.95 $34.50 $45.00 $4.95 Infra Red Movement Detector S39 • 95 : ~ifi~~{EI~1i\i~iif normal use or Normal angle (range 80 ft. plus) for corridor applictions. •. • Snazzy integral mounting brackets allows corner 90 deg. With Two Mode Len, mounting as well as normal surface Q $ (): • I .':'\ .,:· · ;;.;·~:;;= 79.QQ ~{~1:~~if.i:~!:i~¥ff~ .::.~~ Ji,,, Complete with test leads and instructions• Uses Alarm output SPOT 30V 1 a. s__ i,,i,,F-1r-: e_A_ i _a_ ; _: _t~ -~a -~;_$_ T _4_ ~~-ss_M _o _ "_ '_h__ 1_9_1_0_.5_1_~_. .__ :e_~;_~_~:_v~-~_{_1l_r~-~_;_~1f_io_~m_:f_fx_:_:r~-di_r_ie_;_:c_t~-~-~-:T_ec_h~-t~_t_ga_r~-fic-~~-~-re-an_~_1i_i;_~_~_~_;_ie_t~-~-y-0_1_,! STANDAR D DELIVERY & PACKING CHARGE $4.00 to 1Kg $7 over 1Kg AUSTRALI A ........,;:;- · WIDE - We process your order the day received and despatch via. Australia Post . ······ • ··········· Allow approx 7 days from day you post order to when you receive goods ······W···· · 174 Roe St. Perth W.A. 6000 PHONE TOLL FREE 008 999 007 Perth Metro & After Hours (09) 328 1599 ALL MAIL ORDERS P.O. Box 8350 Perth Mail Exchange W.A.6000 AL TRON ICS RESELLERS Chances are there is an Altronics Reseller right near you· check this list or phone us for details of the nearest dealer. Pleaae Note: Resellers have to pay the cost of freight and insurance and therefore the prices charged ~Y individual Dealers may vary slightly from this Catalogue • in many cases, however, Dealer prices will still represent a significant cost saving from prices charged by Altronics Competitors. Don't forget our Expreu Mall and Phone Order Service• for the coat of a local call, Bankcard, Vias or Maatercard holdera can phone order tor aame day deapatch. $7.00 OVERNIGHT JETSERVI CE - We process your order the day received and despatch via. Overnight Jetaervlce Courier for delivery next day Country areas please allow additional 24-48 hours. Weight limit 3Kgs (311:gs covers 95% of Orders). $1 0.00 HEAVY HEAVY SERVI CE - All orders of 10Kgs or more must travel Express Road • Please allow 7 days for delivery. INSURAN CE - As with virtually every other Australian supplier, we send goods at consignees risk . Should you require comprehensive insurance cover against loss or damage please add 1% to order value (minimum charge $1). When phone ordering please request "Insurance". :,.:::::.::.::.:I:::·:·:···:.·:,·,. ..... W · • • ·• ~!:;~~;J,:i~::::::::~ :~•::::::::~~r,: =~ ~'I~ If you have a Retail Shop, you could increase your income significantly by becoming an Altronics Dealer, Phone Fred Bloffwitch (09) 328 2199 for Details. WA COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON K.B .Electronics & Marine 212176 KALGOORLIE Todays Electronics ■ 212777 KARRATHA Daves Oscitronics 854836 MANDURAH Lance Rock Retravision 351246 NEWMAN Watronics 751734 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Ascom Electronics 521713 Farmer Electronics 522967 ACT CANBERRA Bennett Com:11ercial Electronics 805359 Scientronics 548334 VICTORIA CITY Active Wholesale ■ 6023499 All Electronic Components 6623506 SUBURBAN ASPENDALE Giltronics 5809839 CHELTENHAM Talking Electronics 5502386 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston Electronics 4840191 COUNTRY BENDIGO KC Johnson ■ 411411 MORWELL Morwell Electronics 346133 SWAN HtLL Cornish Radio Services 321427 QU EE NSLAND CITY Delsound P/L 8396155 SUBURBAN FORTITUDE VALLEY Economic Electronics 2523762 SALISBURY Fred Hoe & Sons Electronics 2774311 WOODRIDGE David Hall Electronics 80ij2777 COUNTRY CAIRNS Electronic World ■ 518555 BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronlcs 724321 MACKAY Philtronics ■ 578855 NAMBOUR Nambour Electronics 411604 PALM BEACH The Electronic Centre 341248 ROCKHAMPTONAccess Electronics (East St.) 221058 Electron World 278988 Purely Electronics (Shopping Fair) 280100 Xanthos Electronics 278952 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSVILLE Solex ■ 722015 SA CITY Electronic Comp & Equip. 2125999 Force Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 2963531 CHRISTIES BEACH Force Electronics ■ 3823366 ENFIELD Force Electronics ■ 3496340 FINDON Force Electronics ■ 3471188 PROSPECT Jensen Electronics ■ 2694744 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Electronics ■ 454764 T ASMAN IA HOBART George Harvey ■ 342233 LAUNCESTON Advanced Electronics 315688 George Harvey ■ 316533 Nichols Radio TV 316171 NSW CITY David Reid Electronics ■ 2671385 SUBURBAN BLACKTOWN Wavefront Electronics 8311908 CARINGHAH Hicom Unitronics 5247878 LEWISHAM PrePak Electronics 5699770 SMITHFIELD Chantronics 6097218 COUNTRY ALBURY Webb ' s Electronics ■ 254066 COFFS HARBOUR Coffs Habour Electronics 525684 GOSFORD Tomorrows Electronics ■ 247246 NELSON BAY Nelson Bay Electronics 813685 NEWCASTLE Novocastrian Elect.Supplies ■ 621358 NOWRA Ewing Electronics ■ 218412 RAYMOND TERRACE Alback Electronics 873419 TENTERFIELD Nathan Ross Electronics 362204 WINDSOR M & E Electronics ■ Communications 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 Blue Ribbon Dealers are highlighted with a ■. IIB■IIIRIIB;::;: :rn11111:: 1111~~: 11:1•11111:~ •:-:-:•·•:.:•.······y,· ~-= These Dealers generally carry a comprehensive range of Altronic products and kits or will order any required item for you. •••··•••·••··•• ••··•••••••·• ·····••••···•••••· • :.:.;.:,:,:;:,: ~m11:~ ~111:: 1111 . ·.:• :•:•:•:-:❖:-:-:.:•:0:~ •:•: .:-:•:•:•:•:•:<•.:,:.•.·····•·0w •····· PT.6: THE SYDNEY AND BLUE MOUNTAINS SYSTEMS THE EVOLUTION OF ELECTRIC RAILWAYS In this episode, we look at one of the cleverest applications of electrical inventiveness in railway history - the Sydney suburban and Blue Mountains systems. By BRYAN MAHER As all Australians well know, the economic success of our nation depends heavily upon the inland graziers, farmers and miners. Their products must be carried to the coastal ports for export and their machinery and other manufactured requirements need to be transported back to them from the cities. Unit trains (ie, those carrying only one commodity such as wheat} are the fastest and most economical method of shifting large peak loads. In Western Australia, South Australia, Victoria and Queensland this transport presents no speciai problems. But in New South Wales the story is quite different. From the north and north west regions to the wheat, coal and wool port of Newcastle, the Great Dividing Range must be crossed at Ardglen near Murrurundi by a difficult single track climb. If proceeding further south to Sydney, the eight kilometre climb known as the Hawkesbury Bank from Brooklyn to Cowan must be conquered. This continuous heavy 2.5% grade required two or three steam locomotives on every train. An even worse situation existed on the western line. Climbing the Great Divide between Bathurst and Lithgow was no great shakes but the assault on the Blue Mountains was quite a different "kettle of fish". Travelling eastwards from Lithgow the line rises 58 metres in the first 2400 metres of track length. Then, climbing another 100 metres elevation in the next 11.5 km, trains must negotiate ten tunnels up to 786 metres long and reverse curves as sharp as 161 metres radius as they cling to the side of the mountain. The peak elevation of 1067 metres (3500ft} above sea level is reached at Mount Victoria. Wheat and wool trains from the Western Plains and unit coal trains from the western fields all vie with express passenger traffic for space on this line. The big climb A 1928 MODEL SYDNEY SUBURBAN parcel express van. The vehicle weighed 50 tonnes when laden and its 537kW motor gave it excellent acceleration. (Picture courtesy SRA, NSW). 74 SIi.iCON CIIII' In the reverse direction, traffic from Sydney has an easy run to Penrith and Emu Plains then abruptly attacks the Blue Mountains as trains climb 300 metres (985 feet} in the first 18. 7km on a continuous 1-in-60 grade. From Valley Heights, the next 32km of track rises 692 metres (2270 ft} with grades varying from 1-in-47 to as steep as 1-in-33. Add to this the many tight radius reverse curves and you have one of the most difficult railway routes in the world. Passenger traffic is heavy, especially on the eastern side of the mountains. As well as the intersla te, country mail. express and fast XPT trains to such cities as Balhursl, Bourke and Perth . there A 57-CLASS 3-CYLINDER STEAM LOCOMOTIVE attacks the Blue Mountains' grades during late 1956. As this photo shows, the 1500 volt DC wiring is in position above the tracks but full electrification had yet to be completed. (SRA, NSW photo). is also considerable tourist and daily commuter usage. As early as 1949 the NSW Government realised that the existing track load of 54 trains per day each way was almost the saturation limit as freight trains were spending half their time standing in sidings to allow passenger trains to pass. In the foreseeable future, that figure would have to be increased to more than 70 trains in each direction each day. Something had to be done. A 1950 study considered five alternatives: (1). Use larger steam locos; (2). Replace the existing steam locos with large multiple unit dieselelectric; (3). Quadruple the whole track from Sydney to Lithgow; (4). Electrify the line from Sydney to Lithgow using high voltage AC or 3kV DC; (5). Electrify the line from Sydney to Lithgow using 1500 volts DC. Proposal (1) was found to be impossible because of the many very sharp curves while proposal (2) was ruled out because of the poor power-to-weight ratio of the large diesel-electric locomotives of the day (109 tonnes for a 1.34 Megawatt (lB00bhp) unit or 12kW per tonne of locomotive). Other designs were as low as BkW per tonne. With diesel-electric locomotives a large diesel engine drives a generator and this then drives electric traction motors which mechanically drive the wheels . The diesel engine, generator and diesel fuel add much unproductive weight. Calculations showed that on a 1-in-33 up-grade at 56km per hour, approximately half the locomotive's power would be used just in lifting the loco itself up the mountain. Proposal (3) would, if possible, allow freight trains to continue slowly up the mountain while faster passenger traffic passed on a dif- ferent pair of tracks. Such a solution was clearly impossible as parts of the Blue Mountains ridge are so narrow that there is really only room for the existing double track, the parallel Great Western Highway and a few houses. That left electrification as the only workable solution. The choice of "AC or DC and what voltage" was the subject of considerable engineering consideration. Proposal (4) investigations showed both 25kV AC and 3kV DC electric locomotives and multiple-unit passenger trains to be more expensive than the 1500 volt DC alternative. But the real killer of the high voltage proposal was the height of the eleven tunnels. This was inadequate for the long insulator strings needed for high voltage overhead wiring. Furthermore, many of the tunnels continually seep water and leakage or tracking across wet high voltage insulators could be a serious problem. Al'Il/L 1988 75 THE SECOND GENERATION SYDNEY SUBURBAN electric trains were single deck models with improved doors and lighting. The eight 269kW traction motors (2.15MW total) gave these trains remarkable acceleration. (SRA, NSW photo). Another disadvantage of both the 25kV AC and 3kV DC proposals would be the difficulties in joining the mountain system to the existing 1500 volt DC Sydney suburban system which had been in service since 1928. Proposal (5), to electrify at 1500 volts DC, was the only workable solution. This would require heavy copper cables for all overhead wiring and twin pantographs on all locomotives for current collection at thousands of amperes. Furthermore, to keep line voltage drop within acceptable limits, trackside DC substations would be needed at close intervals. Of course, there was the advantage that connecting to the existing Sydney suburban electric system would involve minimum expense. At this point we need a flashback, giving a summary of the salient points of the Sydney suburban electric system. So, gentle reader, let us do just that. Sydney suburban electrics During the 1920s considerable planning was in hand for the City Circle underground and for the 76 SILICON CIIII' electrification of the whole suburban system. Accordingly construction of overhead wiring, feeder cables and electricity substations proceeded apace. With concurrent work on many lines, the honour of being first went to the Illawarra line when the first electric train in New South Wales ran from Central Station through Sydenham and Hurstville to Oatley on the Georges River on 1st March 1926. Within five months the electric system was extended to Sutherland. By 1928 electric trains were running to Parramatta and shortly thereafter to the North Shore via Strathfield and Hornsby. Substations to provide a 1500 volt DC supply for the trains were built beside the tracks at many points within system. All those within the inner circle - Argyle, Sydney, Lewisham, Strathfield, Hornsby, St. Leonards, Parramatta, Sydenham and Hurstville - used transformers and rotary converters to convert 6600 volt 25Hz 3-phase AC from the Railway Power Stations to 1500 volts DC. The largest of these substations was Prince Alfred, just south of Central Sta- tion. Known as "P.A." this substation was equipped with four huge 1500 volt DC 4.5MW rotary converters. Later substations in suburbs further out, such as Regents Park, used water-cooled mercury-arc rectifiers fed via transformers from 33kV 50Hz 3-phase AC. February 1932 saw the first train leave Central, go under the City via the previously unused leftmost tracks, and race through the tunnels to the brand new Town Hall station, after which the train terminated at Wynyard. The Harbour Bridge was opened the following month, allowing trains on the upper level at Wynyard to continue on up into the daylight, and over the Bridge, to join the existing line to Hornsby. Fast train turnaround During peak hours the timetable demanded fast turnaround of trains termina ting and restarting at Wynyard lower level platforms. The driver literally did not have time to walk to the other end of his train. After off-loading passengers at the arrival platform, a train would run northwards into the Quay tunnels and stop. The driver would leave his train while simultaneously another driver would board the other end of the train and drive it back via the Wynyard switching tracks to the outgoing platform. There the train would be refilled with peak hour passengers, and be off to distant southern suburbs. Such organisation helped the Sydney underground system to achieve a remarkable daily peak hour traffic density of one train every 47 seconds. Train details Sydney's suburban electric system is based on the concept of eight-car trains although four-car trains are commonly used in offpeak hours. The standard makeup of a fourcar set is a power car at each end and two trailer cars in the middle, each power car having a driver's control cabin at one end only. From the start, each power car was equipped with a non-motor (or trailing) bogie at the driver 's cabin end and a motor bogie containing two traction motors at the opposite end. Mounted on top of the car at the motor bogie end, an insulated pantograph picks up current from a 1500V DC overhead copper conductor. Power from the pantograph is taken down to the underside of the car to the high voltage contactors, thence to the motors in the motor bogie. Each power car in a train picks up its own high voltage power from the overhead contact wire, so that only control circuits are connected from car to car for the full length of the train. Quite sophisticated for their time, the original 1926 control circuit designs used 32 volt DC electropneumatic contactors to control the high voltage motor circuits. The driver's hand-operated master controller at the front end of an eight car train can easily ca rry enough 32 volt current for all the motor control circuits in all four power cars. The driver's controller has four starting/running positions: (1). The low speed first step causes both motors in each motor bogie and a bank of cast iron starting THE NSW SRA INTRODUCED THESE double-deck inter-urban trains on the Blue Mountains run in 1970. Designed and built by Comeng of Granville, these 1500V DC passenger trains are lighted and air-conditioned by an on-board 415-volt 3-phase auxiliary power supply. (SRA, NSW photo). ·-~'.l... ···- •' ~ ~ - - THE 46 CLASS WAS THE FIRST production electric locomotive used in NSW, commencing service in 1956. This locomotive weighed around 110 tonnes and employed six 478kW traction motors, giving a total of 2.865MW. (SRA, NSW photo). resistances to be connected into one series circuit. (2). The second step engages an "acceleration relay" which senses traction motor current and automatically closes a "notching" contactor when acceleration brings motor starting current back down to 160 amps. This contactor bridges out part of the sta rting resistance, accelerates the train further and raises motor starting current again. When more acceleration brings motor current again down to 160 amps, the next notching contactor is automatically closed, bridging out more of the resistance and thus causing further acceleration. This automatic process continues until all the sta rting resistance is bridged out, leaving the pair of motors in series. (3). The third step connects both motors in pa rallel but in series with the starting resistance. Again the acceleration relay senses motor current and progressively closes notching contactors. cutting out 1\1'/lll. lfl8 /l 77 and that the cars were built in Australia, we begin to appreciate the expertise of earlier years. Motor details INTRODUCED IN 1979, THE SRA CLASS 85 is a CoCo type 1500V DC electric locomotive with an output of 2.88MW. It weighs around 123 tonnes and is capable of speeds up to 130km per hour. (SRA, NSW photo). sections of the starting resistance until the motors are in "full parallel" directly across the 1500 volt supply. (4). The fourth step leaves the motors in "full parallel" but shunts the motor series fields with resistance, thereby reducing motor field strength. This causes the motors to accelerate to still higher running speed, the design maximum being 80km per hour. The driver may leave his controller on any one step or may start from a station by moving his con- troller directly to the highest step, in which case the four steps described will automatically be followed by the equipment in proper sequence. This added safety feature meant that the driver could concentrate on driving and forget electro-mechanical details. As well, the design can make use of the maximum acceleration without wheel-slip on every start, an especially useful feature on the "all stations" runs. When we recall that this level of sophistication was designed, up and running by 1926, The original design specified two axle-hung 1500 volt DC four pole series 360hp (269kW) traction motors with interpoles for each motor bogie. Thus the four power cars of an eight-car train contain between them eight motors totalling 2880 horsepower or 2.15 megawatts. No wonder they can scarper out of the stations. Also each power car is equipped with a 1500 volt DC motor driving an air compressor, and batteries providing 32 volt DC supply for control and lighting, charged by a motor-generator set. New cars were all steel single deck units, the power cars weighing 50 tons, the trailer cars less, giving the original design acceleration figure of 2.08km/h per second. Braking The initial design featured direct air braking using cast iron brake shoes and the repeated stopping of an all-stations train could wear out a full set of brake shoes in a week. As well as the cost of their constant replacement, the clouds of cast iron dust generated when stopping permeated everything. Fitters and other running shed staff continuously engaged in working under trains sometimes found the cast iron dust even entered the pores of their skin, staining clothing many hours later. A later change to plastic composition brake shoes reduced the wear and dust problem but required increased pressure of shoe against running wheel to compensate for the reduced coefficient of friction. Also, as these shoes polish the wheel running surface, the acceleration rate had to be reduced to prevent slipping during starting. Automatic stops THE LATEST SRA LOCOMOTIVE is the 119-tonne 2.88MW 86 class, introduced in March 1983. Fifty of this class have been added to the SRA's fleet. (SRA, NSW photo). 78 SIUCON CIIII' Where tracks approach points, crossovers or junctions, the signals protecting these are equipped with an electro-mechanical arm unit mounted on the track sleepers. When the signal is at STOP (ie, redover-red), the electro-mechanical arm is raised and will hit a small brake trip arm mounted on the left side of the front bogie of every train, shutting off motor power and applying full brakes should any train attempt to run through the stop-signal. An extra safety feature is that the driver must rest the weight of his hand on the controller handle at all times otherwise the train is automatically brought to a stop. Keep in mind, gentle reader, that the basic design of Sydney's suburban system worked out in 1925 proved so successful, both in terms of safety and in density of traffic carried, that no reason has been found to make changes, apart from those brake shoes on the trains and the use of 6-phase mercury arc rectifiers rather than rotary converters in the latest DC substations. By 1953, there was a total of 480 kilometres of track electrified and fed by 18 DC substations. That was the situation in the early 1950s when railway engineers were designing the Blue Mountains electrification. Surely it was a sound engineering decision to extend electrification at 1500 volts DC across the Blue Mountains. Blue Mountains design Because the heaviest trains are those travelling in the eastward direction, and because they drop 1067 metres (3500 ft) in descending the eastern side of the Blue Mountains, full regenerative braking was adopted. This is a system wherein the descending locomotives use their traction motors as generators to feed current back into the overhead wiring to assist other trains which are simultaneously ascending the mountain. Ascending trains using this regenerated current place a load on the descending train's motors [now acting as generators). This loading has a braking effect on the descending train, thus reducing its speed. By using this continuous, steady, even braking method, descending trains do not need to use their air brakes at all, saving wear in the train's many cast iron brake shoes and almost eliminating the cast iron dust menace. However trains still remain fully equipped with air brake systems, TABLE 1: LOCOMOTIVE WEIGHT AND POWER Year Loco Class 1926 1949 1949 1952 1952 1956 1958 1960 1962 1969 1979 1982 1983 1984 1986 1986 1986 Suburb. Elec. Steam Steam DC Elec. DC Elec. DC Elec. Diesel Elec. Diesel Elec. Diesel Elec. Diesel Elec . DC Elec. Diesel Elec. DC Elec. AC Elec. Diesel Elec. AC Elec. AC Elec. NSW 58 38 71 L 46 USA 49 45 422 85 81 86 9E G 3000 3500 Notes: (1 ). The (2). The (3). The (4). The Rall (HP) Rall (MW) Weight (tonnes) 0.537 720 50 2475 1.846 228 2250 1.678 201 2700 2.014 108 2400 1.790 98 3840 2.865 108 1350 1.007 120 0.650 875 80 1800 1.340 111 2000 1.490 108 2.880 3859 120 3000 2.240 126 3859 2.880 117 5067 3.780 168 3000 2.240 128 3887 2.900 109 3887 2.900 109 kW per tonne 10.74 8.09 8.35 18.65 18.27 26.52 8.39 8.13 12.13 13.80 24.00 17.78 24.62 22.50 17.50 26 .60 26 .60 "G" and "L" class are Victorian. "3000" and "3500" class are for Queensland coal trains. "9E" class are South African 50kV locomotives, 3ft 6in gauge. "Suburban Electric" figures are for one Sydney power car. both for emergencies and for bringing a train to a complete stop. As Table 1 shows, in 1956 the power-to-weight ratio of 1500 volt DC electric locomotives was more than three times higher than any contempory steam or diesel-electric type and even today the electric locomotive still wins in this regard by a factor of 35%. Therefore, the electric locomotive uses less of its power lifting itself up the mountain, leaving more useful power to haul the train up the difficult climb. The result of the electrification of the Blue Mountains is that trains even freight trains - race up the mountain at remarkable speeds considering the gradient. Fast freights running at passenger train speeds now spend little or no time standing in sidings waiting for passenger trains to pass, resulting in a doubling of the possible number of trains per day. Between 110 and 120 trains per day now ascend or descend the mountain. Train running time was reduced by electrification from the previous 138 minutes to 74 minutes for the trip to Mount Victoria. For freight trains, 2 hours 30 minutes was sliced off the running time while at the same time maximum loads c_arried have been doubled. Also the journey down the mountain is faster under smooth steady regenerative braking compared to the older periodic application and release that was necessary when using air brakes on long descents. Use of regeneration current by other ascending trains results in 20% less electricity used from the substation. The quantity of traction electricity used can be calculated in terms of coal burnt in the distant power station. The quantity of coal so needed by the power station per electric train is about one tenth that burnt in steam locomotives per train under the old system. This amounts to 150,000 tons of coal saved per year. Locomotive design The electric locomotives chosen were manufactured by Metropolitan Vickers Ltd of England and named the " 46" class. 40 of these machines were made, the first being run on the line on 25th June, A l'!llL '1988 79 1956. The locos and the overhead wiring were designed to allow for double heading, with triple heading provided for on the steepest grades. The 46-class locos used six-wheel bogies with each axle driven by its own traction motor. The six traction motors are Metropolitan Vickers 6-pole series type with interpoles, each motor rated at 477kW (640hp). All traction motors and running wheels run in roller bearings. The motor armatures are lap wound and arranged to run on 750 volts DC. The six motors in each locomotive are arranged to run as three parallel pairs of two motors in series. For low speed running they are switched to two parallel triplets of three motors in series and for starting they are switched to all six motors in series. Starting resistances are also switched in series with the motors, such resistances being progressively bridged out in 19 steps called "notches" by high voltage contactors operated by the driver 's controller. These control circuits are extended by jumper cables to the second (and third) locomotive for double or triple header operation. A circuit of relays and bridge resistors continually tests the equality of voltage drop across pairs of motors. Should one pair of driving wheels begin to lose traction and slip (such as on wet rails), the motor driving that axle becomes mechanically less loaded and hence has less voltage drop across it than the other motors. The relay circuit then informs the driver visually and audibly of this condition. The locomotive fleet wa s aug- SUBURBAN ELECTRIC TRAINS have carried millions of passengers across the Sydney Harbour Bridge since its opening in 1932. (SRA, NSW photo). mented in 1979 by the 85 class electric locos. These were followed by the "86" class in 1983, 50 of this latter class eventually being added to the fleet. The tourist and commuter traffic is now handled by double-decked air-conditioned multiple unit electric trains. Parallel work on the Sydney suburban system resulted in double-decked trailer cars in 1964 and complete double decked suburban electric trains by 1968. By 1984 the electrification of the main line from Newcastle to Sydney was completed and today electric passenger and freight trains also operate from Sydney to Wollongong and Port Kembla on the Illawarra line, all of which use the same 1500 volts DC system. Victoria Other DC electric railways in -----====---' ~- t!~ I', f □ Australia are the extensive Melbourne suburban passenger system, which uses 1500 volts DC, and the V-line electric locomotives for coal and freight in Gippsland in Eastern Victoria. Here the " L" class electric locomotives, also operating on 1500 volts DC, are CoCo type; ie, two six-wheel bogies with all axles driven. The six traction motors are English Electric Type EE519 , each rated at 298kW (400hp ), giving the locomotive 209 kilonewtons tractive effort during starting. For electric dynamic braking, their traction motors ac t as generators with the electricity thus generated being absorb ed in resistors mounted within the locomotive. With a total weight of 98.6 tonnes, and a length of 18 metres, these locomotives are capable of speeds of 121km/hr. 0 b::I 0 if__:=~--~cl ~) I Y C:> v/;LINE w [y [O ~ I - -- - THE VICTORIAN "L" CLASS 1500-volt DC locomotive is propelled by six traction motors, each rated at 298kW. This 98.6-tonne Coco locomotive is used for hauling much of the coal train traffic in the south-eastern corner of Victoria. (Drawing courtesy V-LINE). 80 SILICO N CI-111' DIGffAt ~ F . ->, ' In this chapter, we '11 discover' how gates and inverters are combined to perform unique aµd specific logic functions. - .......... ,t,~ LESSON 6: COMBINATIONAL LOGIC CIRCUITS By Louis E. Frenzel A combinational logic circuit is a collection of gates and inverters that performs some specific logic function. A combinational logic circuit has two or more inputs and one or more outputs. The output is dependent upon the types of logic circuits used and how they are interconnected. The output is also a function of the binary input states. The operation of such a circuit is generally expressed in the form of a truth table where the binary states of the inputs are listed, as well as the corresponding outputs. Fig.1 is a block diagram of a combinational logic circuit, showing its inputs, outputs and the related truth table. As you might suspect, there is an enormous number of ways that you can interconnect gates and inverters to form various combinational logic circuits. On the other hand, there are many commonly used combinational logic circuits; so common, in fact, that manufacturers have constructed them in MSI and LSI form, thereby eliminating the need for the user to intercon- nect individual gates and inverters. Some of the more common logic circuits include decoders, multiplexers, demultiplexers, exclusive OR gates, and many others. When one of the standard -circuits cannot be used, custom logic circuits for special applications can be built with programmable logic arrays (PLAs). PLAs are a type of LSI circuit that permit a designer to interconnect arrays of AND gates, OR gates, and inverters within a single chip to produce a desired logic function. When you complete this lesson, you will have a working knowledge of all the most commonly used combinational logic circuits, including PLAs. New Logic Symbols Before proceeding to a discussion of combinational logic circuits, we want to introduce some of the newer symbols used to represent logic circuits in schematic diagrams. By now, you are already familiar with the symbols for AND, NAND, OR, NOR and other circuits. Those commonly used symbols are illustrated in Fig.2. Such logic symbols have been used for many years, but now are gradually being replaced by newer symbols. _ _ _ : }OUTPUTS COMBINATIONAL LOGIC CIRCUIT Fig.1: general block diagram of a combinational logic circuit and its related truth table. =D- =D- =D-- =D- ANO A B C X y 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 0 0 0 1 0 0 0 1 0 1 0 1 0 0 0 NANO -p,INVERTER (NOT) OR NOR Fig.2: the old and still most commonly used logic symbols. JK FLIP-FLOP APillL 1988 81 =E}- -0- =GOR AND INVERTER (NOT) =8NAND JK FLIP-FLOP Fig.3: the new logic symbols are easier to draw. The new symbols are shown in Fig.3. As you can see, each symbol is nothing more than a square block with input lines on the left, output lines on the right, and some designation in the block that tells what it does. A triangle at the output means inversion or the complement. A triangle at the input signifies that the input must go low to initiate the operation (active low input). Note the use of ampersand for AND and 1 for OR. We will be using the new logic symbols, as well the old ones, in the various circuits to be described to help you become familiar with them. In addition, other new logic symbols will be introduced, along with some of the combinational logic circuits as they are discussed. Decoders A decoder is a binary number detector; ie, it recognises the existence of one particular binary number. If the binary number for which the circuit is set up appears at its inputs, the decoder output will be a binary 1. For any other binary-input number, the decoder output will be binary O. The primary element in a decoder is an AND gate. Naturally, a NAND gate can be used as a decoder if an active low output is satisfactory. For example, suppose you wish to detect the presence of the two-bit binary number AB, where A = 1 and B = 1. All you have to do is apply those two bits to an AND gate as shown in Fig.4a. When those two bits are present, the output of the AND gate is binary 1. If any other two-bit combination appears at the input, of course, the output will be binary 0. Now suppose we wish to detect the two-bit binary number AB where A = 0 and B = 1. Again, we use an AND gate for this purpose. However, there is a problem here because if either input is binary 0, the output of the gate will be binary O as well. To eliminate that problem, we simply put an inverter between the desired input signal which has the value binary O and the input to the decoder AND gate. This is illustrated in Fig.4b. Now, when the binary number 01 appears at the decoder input, the inverter turns the binary O into a binary 1, so that the output from the AND gate is also binary 1, thereby indicating the presence of the number. Fig.5a shows how you would decode the binary number 0110. A 4-bit number requires a 4-input AND gate. Inverters are used on the two lines whose inputs are 0. Fig.5b shows an 8-input AND gate used to detect the presence of a specific byte, in this case 00111010. Note the use of inverters at the appropriate points. Also note that this decoder is a NAND gate. Therefore, when the correct number appears at the input, the output of the gate will be a binary Oinstead of a binary 1. While decoders are often implemented with individual gates, usually it is desirable to decode all possible states of a given binary word size. For example, a 2-bit binary number has four possible states, 00, 01, 10 and 11 or AB, AB, AB and AB. A separate 2-input AND gate is used to detect each one. Inverters are used at the inputs to provide the complement signals where necessary. Fig.6 shows a decoder of that type. The two-input lines are decoded into four possible outputs. As a result, such a circuit is ~om~times called a two-line to four-line decoder. Keep m mmd, however, that only one output will be binary 1 at any given time. Depending upon the input word applied, only one AND gate will be activated and only one output will be high. For that reason, a decoder circuit such as that is often referred to as a 1-of-4 decoder. The inputs and outputs of such a circuit are illustrated in the truth tabla of Fig.6. A popular MSI decoder circuit is a 3-line to 8-line 0 0 OR 0 0 OR & 0 A=D-r B (a) . & (a) lb) Fig.4: simple decoder circuits using old and new symbols. 82 SIUCO N CIIII' Fig.5: four-bit (A) and eight-bit (B) decoder circuits using the old and new logic symbols. lb) AB = W AB =X AB = Y AB A B w X y z 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 1 1 1 =Z Fig.6: a two-line to four-line combinational logic circuit (or one-of-four decoder circuit) and its truth table. decoder as illustrated in Fig, 7. The inputs are A, B and C. The outputs are labelled Y0-Y7. Such a decoder is often referred to as an octal decoder because is has eight outputs. You will also hear such a decoder referred to as a 1-of-8 decoder. In this circuit, NAND gates are used; therefore, the output of the gate will go low when it recognises a specific 3-bit input code. In other YO A Y1 Y2 SELECT INPUTS 8 Y3 DATA OUTPUTS C words, in this circuit all output lines are high except for one, which is the gate that is the decoding the correct input. Note that the circuit has three control inputs also. Those control inputs are used to enable or disable all of the decoder gates. To enable the circuit, Gl must be high and G2A and G2B must be low. The new logic symbol for this circuit is also shown in Fig.7. Note the designation BIN/OCT which means "binary in and octal out". Also, notice the "&" box, which defines the control inputs. Other popular decoders include the BCD-to-decimal decoder and the hexadecimal (hex) decoder. The former accepts the standard 4-line BCD input and activates one of its ten outputs, 0-9. This circuit is also referred to as a 4-line-to-10-line or 1-of-10 decoder. The hex decoder is a 4-line-to-16-line or 1-of-16 circuit. Both are available as MSI !Cs. Multiplexers Another widely used combinational logic circuit is the multiplexer. A multiplexer is an electronic switch that allows the selection of one of several input signals. Also called a data selector, the multiplexer chooses one of the inputs and passes it through to a single output. The circuit is essentially equivalent to a multi-pole selector switch as shown in Fig.8. A digital version of a multiplexer is created with AND and OR gates. The AND gates are used to select one of several inputs, while their outputs are ORed together to generate a single output. Such a multiplexer with four inputs is illustrated in Fig.9. Only one of the four AND gates will be enabled at a given time and its output will be passed through the OR gate to form the output. Such a circuit is referred to as a 1-of-4 data selector. Y4 2 Y5 0 6 7 .8 r ENABLE INPUTS Y7 b oo/r 0 INPUTS Y6 b OUTPUT INPUT 7 IS SELECTED Fig.8: an e quivalent circuit for a multiplexer. 628 G1 01 xv 02 BIN/OCT A ~ L B Y1 XY INPUTS OUTPUT DJ xv Y2 Y3 04 XY Y4 EQUIVALENT T / ~ YO G1 G2A Y5 & Y6 Y7 628 2-LINE TO 4-LINE DECODER NEW SYMBOL Fig.7: an octal or 1-of-8 decoder circuit shown in the old and new logic symbols. X y ADDRESS Fig.9: a 1-of-4 selector or multiplexer. APHIL 1988 83 Free Teletext! Yep, the Teletext transmissions are yours absoutely free of charge, courtesy of your local TV station (not in all areas - sorry!). All you need is a Teletext decoder to pick up the latest news, sports results, financial info, stocks and shares, recipes, etc. Build your own Teletext decoder - it works through your VCR so you save a fortune. Complete with hand controllers. Cat K-6315 Radio Direction Finder Here's a great first "big" project. When you've finished mucking around, build an amplifier! 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Cat W-2099 $3.15/1111111 !In· 1eoAH 'AA' 500AH 'C' 1800AH 'D' 1200AH Cat No. S-3350 S-3351 S-3352 S-3353 75 0~111 R6-~. As used by most TV antenna installers. Price Cat W-2081 &Oc/1111111 $4.95 $4.75 $12.95 $10.95 75 0~11 High quality, low loss TV coax. Cat W-2082 BOc/1111111 300 Ohm TV Ribbon For indoor and outdoor use. Black iri colour. cat W-2070 25C/1t18111 30% OFF/ PCB Marking Kit Mains Clbla Just draw the resist straight onto the PCB surface! Easy and quick. Great for those 'one of' boards, repairs prior to etching or where there's no photographic facilities available. Cat N-5175 3 Pin IEC Line Plug The type used in an enormous range of equipment including computers, entertainment systems, amateur gear, etc, etc. Stock up While they're down! Cat P-5580 ~~~~ !?~~~!ar Anten'l~c~:.~:1P,a~Jors Save $50! Solder - Hobby Packs The economical way to buy solder for the hobby bench or workshop! Just the size to suit most jobs. sf!IHI 1.25mm diameter in 200g roll. 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Cat S-1077 Save $1 $2.95 Just the thinp for those small jobs like your average projects, etc Available in the two most popular sizes. 0.71mm diameter (22g) in 9 meter hobby pack. Cat N-1636 1.25mm diameter (17g) in 4 metre length Cat N-1638 1 AJO Twin & Eartll: Light Duty, 1 x .113. Rated at 10A with insulated earth. Cat W-2060 95C/IHl11 Twin: 7 x 0.050. Power use (rated at 25A) where separate earth wire used. Cat W-2061 $1.40/111111 Twin and E1rtll: 7 x 0.050. Power use with insulated earth. 20A rating . Cat W-2062 $1.50/111111 Mains Fltx: 3 core grey flex for extension leads, etc. 7.5A Rating. cat W-2055 WAS 9/ie NOW 65C/ltlllre D1t1 Cable: Fully shielded cable specifically intended for fixed data communication lines. 5 Core: Cat W-2040 $1.85/IHlre 12 Core: Cat W-2041 $2.50/1111111 DS K TS • NSW• Armidate: Sound Components. 244 Beardy St, 724981 • Ballina: Ballina Electronics. 102a River St, 86 7022 • Bowral : F.R.H. Electrical, 28 Station St, 61 1861 • Broken Hill: Hobbies & Electronics, 31 Oxide St. 88 4098 • Charlestown : Newtronics. 131 Pacific Hwy, 43 9600 • Catts Harbour: Coffs Harbour Electronics, Shop 3 Catts Habour Malt, Pa rk Ave, 52 5684 • Oeniliquin: Deni Electronics. 220 Cressy St. 8 1 3672 • Dubbo: Chris's Hi-Fi , 1/ 100 Talbragar Street. 82 871 1 • Forster: Forster Village Electronics, Shop 36, Forster Shopping Village, Breese Pde, 54 5006 • Griffith : Miatronics , 166- 170 Ban na Ave, 62 4534 • lnverell : Lyn Willing Electronics. 32 Lawrence St, 22 182 1 • Leaton : Leeton Record Centre, 12 1 Pine Ave, 53 2081 • Moree: Moree Electronics . 26 Balo St. 52 3458 • Parkes: Strad Music Centre, 279-281 Clarinda Stree!, 62 3366 • Port Macquarie : Hall of Electronics, The Horton Centre, 124 Horton St, 83 7440 • Orange: Fyfe Electronics, 296 Summer St, 62 64 91 • Taree: Brad's Electro nics. Shop 6. Civic Cinema Centre, Pulteney St, 52 6603 •Tumut: Tumut Electronics, 62 Russell St, 47 163 1 • Ulladulla: Paul s Electronic & Hobby Toys, Shop 1, 10 Wason St, 55 2454 •Wagga: Philli ps Elect ronics . 60 Fors)'1h St, 21 6558 _ PTY LTD • Wellington: Wellingto n Electrical Service, 110 Lee St. 45 2325 • Young: Keith Donges Ele.ctronics . 186 Boorowa St, 82 1279 •VIC• Dunolly: Fin ders Pty . Ltd ., 90 Broadway St, 68Tj3:f • ~oe: f he Moe Sto re, 56GeorgeSt. 27 2 155 • Morwell : Mo rwell Etectro nics . 3 5 Holmes Rd.34 6 133 •Shepp arton : Phillips Electro niC"SPly . Ltd ., 137 High St. 219497 •Warragul: Roylaine Pty. Ltd , 16 Smith St, 234255 •Warrnambool: Mar-troni.:s , Shop 12, Norfolk Plaza , 743 R<1glan Pde, 62 9870 •OLD• Bundaberg: Bob Elki n Electronics. 81 Bou rbong St, 72 1785 • Caloundra: Electro- Mart, 9 Tay Ave. 9 1 8533 • Dysart: Dysart Videotronixs . Shop 1, Jacaranda Crt Shoppi ng Cenlre. Oueen Elizabeth Drive, 58 2107 • Kawan a: Splitec , Shop 5, Ca rtwright Centre , Nicklin Way , 94 7349 • Mackay: Stevens Electronics . 42 Victo ri a St, 5 1 1723 • Maryborough : Ke ller Electronics, 218 Adelaide St. 21 4559 • Mt Isa: Outback Eteclrc riic-s, Shop 71, Barkl y Hwy, 43 3475• Nambour: Nambour Electronics , Shop 4, Lewan House, An n St, 41 1004 • SA• Mt Gambier: Hutchessons Communications Centre, 5 Elizabeth Sl , 25 0400• Murray Bridge: Bridge Communications, 246 Aclelaide Rd , 32 6476 •WA • Geraldton: Batavia Liphting & Electrical, 98a Chapman Rd , 23 184 2 • Harvey: Harvey Sales& Hi re Services, 94 Udur. Road. 291819 • Kalgoorlie: Todays Electronics. 295 Hannah Street, 21 5212 • Karratha: Dave's Oscitro nics, t st Floor , Savings House, Hedln nd Place . 85 4836 • Port Hedland : Ivan Tomek Electronics, 30 Anderson Street, 73 253 1 • TAS • Devon port : A.1. Electronics & Hobbies. 165 William St. Fourways 24 8322 •NT• Alice Springs: Farmer E!eclronics, 3 1 Elder St, 52 2380 ELECTRONICS cuit. Note also that both normal (Y) and complement (W-bar) outputs are available. The old and new logic symbols are illustrated. Demultiplexer A demultiplexer is simply the opposite of a multiplexer. It has a single input and multiple outputs. It is equivalent to the data selector switch shown in Fig.12. An electronic 4-output demultiplexer - the 74139 2-line to 4-line demultiplexer which contains two identical circuits - is illustrated in Fig.13. Acommon input line [enable) is connected to each of four AND gates through an inverter. The additional inputs on each NAND gate are used for decoding. Inputs A i; DC • i- Dl DATA 2 ' J I ' ' )-- t-- D2 I I I ' }- o-03 ' ' ' Fig.10: the 74173 integrated circuit is a dual selector/multiplexer combinational logic circuit. 86 SILICON CHIP -- ~ ' ,,..._ D5 To select the desired input, a 2-line-to-4-line (1-of-4) decoder circuit is used. It accepts two control inputs, X and Y, that arm an address (0 to 3 or binary 00 to binary 11 ). Depending upon which of the four input codes are applied, one of the four inputs will be selected. For example, if the address is binary 10, gate C will be enabled and D3 will pass through to the output. In practice, a separate decoder is not required because the AND gates used for selecting the inputs can also serve double duty as decoders. Fig.10 illustrates how 4-input AND gates can be used to form a 4-to-1 multiplexer - in this case, a dual 1-of-4 dataselector/multiplexer. The upper and lower multiplexers shown in Fig.10 are identical. Control lines A and B form the address, which is applied in various combinations to the AND gates. Notice also that inputs to be selected (IC0 through IC3 and 2C0 through 2C3) are also applied to each gate. Finally, the fourth input of each AND gate is connected to a single common line and an inverter. That line is used for enabling or disabling the entire circuit. When the 1G input is low, the upper multiplexer is enabled. When the 2G input is low, the lower multiplexer is enabled. Larger multiplexers can also be constructed. An 8-input multiplexer or 1-of-8 data selector is shown in Fig.11. A 3-bit address (ABC) is used to select one of the inputs D0-D7. Common line G-bar enables the cir- - ,- i D4 . D6 07 A DATA SELECT (BINARY){ I . ~ B C ' I .. ..__ ..___ ' DATA INPUTS .' I ·- t:t= J-- ' ·' ' ' J .... . c MUX A B DO y D1 02 w D3 04 05 D6 07 Fig.11: a 74151 1-of-8 data selector/multiplexer integrated circuit chip is illustrated using the old and new logic symbols. y w INCLUSIVE OR Jc,___ ,------o 0 EXCLUSIVE OR :.=:D--C=A+B ----1D-- -- A ---/. B C= AB+AB 2 INPUT ~ J o---4 OUTPUTS o---s Fig.12: a demultiplexer equivalent circuit. and B form an address, which enables one of the four gates. Therefore, the single input will be passed through the AND gate that is enabled. If you look carefully at Fig.13, you will see that this circuit is for all purposes a 2-to-4 line decoder. The only difference is that a common input line (enable) is shared by each of the gates. When used as a demultiplexer, the signal to be distributed to one or mor13 of the outputs is applied to that input line. When used as a decoder, the input can simply be ignored or used to enable or disable the circuit. Exclusive OR Gate The OR gate that we discussed previously is a logic circuit with two or more inputs and a single output. Its output is a binary 1 if any one or both inputs are binary 1. The proper name for such a circuit is inclusive OR. However, it is possible to construct an exclusive-OR circuit. An exclusive-OR or XOR gate, as it is referred to, has two inputs and a single output. Its output is binary 1 if one or the other, but not both, of its inputs are binary 1. A truth table for that circuit is shown in Fig.14 along with the symbols used to represent it. Compare the truth table for the exclusive OR to the truth table for the inclusive OR gate. The designation inside the new logic symbol ( - 1) designates the XOR function. In Fig.14, note the Boolean logic expressions for the output of the XOR circuit. In one version, the exclusive A B C A B C 0 0 0 0 1 1 1 1 0 1 1 1 0 0 1 1 0 1 0 1 0 1 1 0 Fig.14: the inclusive OR and exclusive OR (XOR) gates. Note difference in truth table when both inputs are binary 1. OR function is designated by a positive sign with a circle around it. You will often see. the expression for an XOR written in that way. Using the standard Boolean algebra expression for this circuit, you can easily see a way to implement it with standard AND gates, OR gates, and inverters. A typical circuit is shown in Fig.15A. A standard 2-input NAND gate can also be used to construct an XOR circuit. Two other approaches are illustrated in Fig.15b and 15c. Both perform exactly the same function, but in slightly different ways. The circuit in Fig.15b requires five gates, two connected as inverters. The circuit of Fig.15c can be made from a single quad 2-input NAND IC such as the 7400. In practice, it is not usually necessary to implement your own XOR circuits with gates like this. Complete XOR circuits are available already prepackaged in several IC forms. The common configuration is four XOR circuits per chip. An example is the 7486 TTL IC. XOR Applications True/Complement Circuit - Fig.16 shows how you can use an XOR gate to construct a true/complement circuit. That circuit accepts a 4-bit binary number DO-D3. Each bit is applied to one input of an XOR gate. All of the other XOR gate inputs are connected together to form a common control line. C =Aii + AB =A(±) B 1YO ENABLE 16 1Y1 (a) 1Y2 SELECT INPUTS 1A 1Y3 18 DATA OUTPUTS 2YO ENABLE 26 2Y1 2Y2 2A SELECT INPUTS 2Y3 28 Fig.13: a 74139 dual 2-line to 4-line demultiplexer. (C) Fig,15: three ways to implement an XOR gate. i\l'/ll/, 1988 87 I I I I ~___,I E3 E3 TRUE (NORMAL) OR COMPLEMENT OUTPUTS - Fig.16: true/complement circuit using XOR gates. C= :_ __,)[)o--c :__ .......,□i----- Aii + AB A B C 0 0 0 1 0 1 1 0 0 0 , 1 Fig.17: here are three ways to illustrate an exclusive NOR (XNOR) gate. If the control line is held at binary O level, the 4-bit binary word will simply pass through the gates and appear at the output unmodified or in "true" form. However, if the control line is made binary 1, the 4-bit word will be inverted by the XOR gates. The complement of the 4-bit input word will appear at the outputs. Comparators - A comparator is a circuit that compar_es ~inary numbers and generates an output signal mdicatmg when they are equal. A simple comparator can be constructed with a variation of the standard exclusive OR gate. Such a circuit is known as the exclusive NOR or XNOR. It is simply an XOR gate with an inverter at its output. Fig.17 illustrates the logic symbols used for this circuit. Also shown is the truth table for the circuit. Note that whe~ two inputs are equal (either both binary O or both bmary 1), then the output is binary 1, signaling the fact that they are equal. When the two inputs are opposite of one another, the circuit output is binary o. As you can see, the XNOR circuit is a simple 1-bit comparator. Comparator circuits for multi-bit binary words can be ~armed by using multiple XNOR gates and ANDing their outputs together as shown in Fig.18. That circuit is a 4-bit binary comparator. It compares two 4-bit words. One word is represented by bits X1-X4, while the other word is represented by bits Y1-Y4. The corresponding bits in each word are applied to an XNOR circuit. Fig.18: a 4-bit binary comparator combinational circuit. 88 SILICON CHIP ODD Fig.19: a simple 4-bit parity generator. CONTROL 0 = OUTPUT TRUE 1 = OUTPUT COMPLEMENT _,)D----[>o- PARITY BIT ) ~ ~ U T P U T EVEN 4-BIT WORD IN REGISTER 7486 A_ _ )D----~' If all the bits in the two words are equal, the output from each XNOR circuit will be binary 1. Therefore, ~he outpu_t from the AND gate will be binary 1, signalmg equality. If any one or more of the bits in the word are different, then one or more of the XNOR outputs will be binary O and the AND gate output will be zero, signaling inequality. To compare larger words, simply a?d more XN_O_R circuits, one for each pair of input bits, and additional AND gate inputs. As with most other types of combinational logic circuits, it is not necessary to build such comparators yourself. Once again, standard MSI comparator ICs are available and are widely used for address comparison in computer memories and peripheral interface circuits. Parity Checker/Generator - XOR circuits are also ?-sed in parity generator and checker circuits. Parity is a system of error detection sometimes used in digital circuits. As a binary word is transferred from one circuit to another or otherwise manipulated, bit errors can occur. One of the bits in a number that should be binary 1 could be transmitted as a binary O or vice versa because of some intermittent circuit fault or noise glitch. The resulting data will, therefore, be incorrect and could cause problems. For example, errors frequently occur when data is stored in or read out of a memory circuit. Parity generator and checker circuits can be used for detecting such errors. The parity system causes one additional bit to be added to a binary word for the purpose of detecting errors. If the total number of binary 1's in the number plus the yarity bit is odd, then we are said to be using odd parity. On the other hand, if the total number of binary 1 's in t~e number plus the parity bit is even, then we are usmg even parity. Some examples of odd and even parity are illustrated below. Look them over to be sure that you understand the concept. 10110001 10110001 11001110 11001110 1 0 0 1 Odd Parity Even Parity Odd Parity Even Parity XOR circuits are used in the parity generating proces~. The circuit shown in Fig.19 shows a simple 4-bit parity generator/checker circuit. Each XOR circuit l~oks_at a pair of bits and generates a new signal, indicatmg that the bits are the same or different Those output signals are, in turn, connected to XOR circuits and the process is repeated until a single output is ?enerated. That circuit generates a parity bit, which is added to the binary word from which it was g~ne~ated. ~ote t~at an inverter at the output of the circmt provides either odd or even parity. Once a parity bit has been generated, it is usually transmitted and/or stored along with the binary word. At the receiving end, another parity generator circuit looks at the received word and a new parity bit is generated. The new parity bit is then compared with the one that was transmitted. That is done in, an XNOR circuit. If the two bits are the same, then no transmission error has occurred. However, if the generated and received parity bits are different, an error is indicated. That signal can then be used to indicate an error condition and possibly initiate some corrective action. As with previous circuits, parity generator/ checker circuits are available in integrated form and need not be seperately constructed from XOR gates. Binary Adder - The main processing circuit in a digital computer or microprocessor is referred to as an arithmetic logic unit [ALU). At the heart of the ALU is a binary adder that permits the computer or microprocessor to perform addition, subtraction and other arithmetic operations. It is the exclusive OR circuit that forms the base for the binary adder circuit. The addition of binary numbers is a simple process. The rules are illustrated below. 0 0 1 1 A +o +1 0 1 +0 1 +1 10 +B C A+B=C Using those rules, you can easily 0 0 0 see how two multi-bit binary 1 1 0 numbers can be added. The ex1 0 1 1 0 1 amples below show how it is done. Work through the examples yourself to be sure that you understand how carry operations are dealt with. 6 +10 16 0110 +1010 10000 25 +26 51 11001 +11010 110011 To produce binary addition, we need a circuit that carries out the rules illustrated above. If you assume that each of the rules of binary addition shown above represent an entry into a truth table, you will see that an exclusive OR circuit is defined. The carry operation can be performed with a simple AND gate, Therefore, an XOR circuit and an AND gate together form a simple 1-bit binary adder, normally referred to as a halfadder, as shown in Fig.20. er? :--~--CD-suM ,m,oo, Fig.20: the half-adder circuit uses just one AND gate and one XOR gate. The reason it is called a half-adder is that it only adds two bits and does not take into consideration the need to add in a carry should it be necessary. To accomplish this, two half-adder circuits are combined to form a full-adder circuit as shown in Fig.21. Here the half-adder made up of gates A and B adds the two input bits. The sum is added to any carry input that might be present. That's accomplished with the halfadder made up of gates C and D. Gate Eis an OR gate that simply creates a carry-out signal for the next stage. Fig.21. a full-adder combinational circuit. FULL ADDER B c o - - - -- Cl Q ii Kt-+-OC CLOCK Fig.22: a serial full-adder for 8-bit words. A single bit full adder such as this can be used to add multibit binary numbers. That can be done by storing the numbers in shift registers, then shifting the numbers out a bit at a time in synchronism with a clock, as illustrated in Fig.22. Here, two 8-bit shift registers hold the numbers to be added. The adder generates the sum of the corresponding bits in the shift registers a bit at a time as the clock pulses shift the word out. The resulting sum is fed back to the input of the upper register for storage. To avoid the loss of the carry signal generated by each pair, a flipflop is connected to the carry output of the adder circuit. The flipflop is used to store the carry temporarily so that it can be added into the next bit position as needed. Rarely are serial adders like this used any more. Instead, multiple adder circuits are used so that the addition of parallel binary words can be accomplished. Fig.23 shows a parallel adder for two 4-bit binary numbers A0-A3 and B0-B3. The corresponding bits in each word are applied to each adder. Note how the carry output of one adder is fed to the carry input of the next adder. Also note that only a half-adder is required in the least significant bit position as there is no carry in. Four-bit parallel adders like this are available in S2 S3 so S1 LSB co co 83 A3 FULL ADDER 82 A2 Cl 81 Al BO AO Fig.23: a parallel full-adder circuit for two 4-bit numbers. APRIL 1988 89 INPUTS X = FUSIBLE LINK CONNECTED OUTPUTS Fig.24: a generalised circuit for a programmable logic array. MSI circuit form. Most of those circuits are extremely sophisticated and perform not only addition but also subtraction, as well as many other logic functions. Such circuits are used as the basis for an arithmetic logic unit (ALU) in digital computers. Programmable Logic Arrays While a high percentage of digital applications can be implemented with the combinational logic circuits just discussed, there are also many applications that require special circuits. Those special circuits can often be made from the available combinational circuits, plus random gates and inverters as required. While the resulting circuit usually performs the desired function, a good number of chips must be U8- Serviceman' S Log continued from pag-e 90 which is, I believe, still the original material. When I think of the times a solid state MHA gets blown out by lightning, or zapped by some illegal CB afterburner, I wonder why they ever stopped making valve type MHAs. My friend was lucky to have asked me for an old valve. I did not throw away my valves when I stopped using them. They are stowed under the house, out of the way and almost forgotten. I still have some 6J8s, 6U7s, 6B8s, 6V6s, and 5Y3s. Can anyone remember what they were used in'? 90 SILI CON CI-111' ed. These chips take up a lot of space, consume power, require larger circuit boards and occasionally are not fast enough. All those problems can be overcome by using a programmable logic array (PLA). A PLA is an LSI or VLSI circuit consisting of multiple gates and inverters arranged on a chip in such a way that they may be randomly connected to perform almost any logic function. Semiconductor technology now permits manufacturers to quickly, easily and inexpensively manufacture custom circuits using PLAs. Other PLAs are field programmable. That is, the designer may specify his own circuit, then implement it himself with a PLA. Such circuits make it possible to replace MSI functional combinational circuits and all And another query: the twin triodes in the 6ES8 were described as being run in "cascade", meaning one under the other, like a waterfall. In my dictionary, a waterfall is described as a cascade. I have never found anyone who can explain why an electronic cascade is spelled "cascade" . Do you know'? Thank you J.L., for that little piece of nostalgia. I can't offer any explanation as the origin of the word "cascade", but I doubt whether it has any particular linguistic significance. I imagine it was nothing more than a sudden inspiration by someone groping for a term to describe the new circuit concept. Regarding the supply of power to the old MHAs. I cannot recall any systems where 240V was run up the mast, and it would have been a rather complex and expensive setup. As I recall, the most popular arrangement used the feeder as a supply line, power being fed up it at some convenient low voltage typically 32V if I remember correctly - to a transformer in the amplifier which supplied the required voltages. As to whether anyone can remember the valve types you mention: yep, I sure can; they are part of our history! ~ Fig.25: PLAs are programmed by means of fusible links in the integrated circuit chip. 1 I . 0 f1~~i 4) C I) 4) l 4, of the random gates and inverters normally required to implement a special function. In some cases, the entire circuit can be reduced to a single PLA chip. A general block diagram of one type of PLA is shown in Fig.24. The circuit has multiple inputs with inverters and buffers to supply normal and complement signals. Those lines can be interconnected with any one or more of the inputs to the many AND gates on the chip. The AND gate outputs are, in turn, connected to the OR gates as shown. The circuit outputs appear at the OR gates or the associated inverters. Most practical circuits have many more input and output lines than shown. A typical circuit might have eight inputs and eight outputs. The interconnection of the various signals on the chip take place in a variety of ways. One common way is to use fusible links as shown in Fig.25. Each AND gate input is connected to all input lines with a tiny tungsten fuse when the circuit is manufactured. Then the chip can be " programmed" by passing a high current through the appropriate chip pins. The high current will open the fusible links where no connection is desired. In that way, the circuit can be customised to the application which is why PLAs are so popular. Reproduced from HANDS-ON ELECTRONICS by arrangement. Copyright (c) Gernsback Publications, USA. ~ SHORT QUIZ 6: COMBINATIONAL LOGIC CIRCUITS 1 . Combinational circuits may contain flipflops. a. True b. False counter is incremented by the clock , the output is observed . Which of the following functions is baing carried out: a. Decoding c. Binary addition b. Demultiplexing d. Parallel-serial conversion 2. Identify the logic circuits shown in the figure below by filling in the correct names : :=G-c ~ (a) (b) e-Q- ~ 7. Parity is a scheme tor _ _ _ _ _ _ __ 8. Give the parity bit tor each word below: a. 10010010 Odd parity= _ _ _ __ b. 10111101 Even parity = _ __ _ _ (d) (c) 9. Add the following binary numbers: a. 1001 b. 10011110 0111 b. 111 10101 a. b. c. 10 . The following is the truth table of which circuit? d. 3 . Draw a decoder circuit that outputs a binary 0 when it recognises the binary number 10111101 . 4 . A 3-line to 8-line decoder is sometimes called a(n) _ __ __ _ _ _ _ __ __ __ _ _ 6 . Three flipflops of a binary counter are connected to the A, B and C inputs of the 1-of-8 multiplexer shown in Fig .11 . A data byte (8-bit word) is applied to the D0-D7 inputs. As the I J '\.. I I I ~o ( AB11B 0!601 aIqBWWB1601d t!ONX ·q t!OX P (sov) ~ ~oo ~oo ~ ~ ·q (9 ~) 000 ~ ' B Q = Aj!JBd ua113 - ~0~~~~0~ 0 = Al!JBd PPO ·o WO WO~ ·-e UO!P9l9P 10113 C 0 1 1 0 1 0 a. OR b. XNOR c. OR d. XOR 12 . An LSI/VLSI circuit that can be customised to eliminate combinational circuits made with SSI and MSI circuits is called a _ _ _ _ __ _ _ ANSWERS TO QUIZ r-4---o 8 11 . A single-bit comparator is called a: a. AND c. OR b. XNOR d. XOR 5. Another name tor the data selector is _ _ _ I A 0 0 1 .G ~ .~ ~ ·o~ 6 ·q ·g .L ·1nd1no a41 lB AIIB!\Uanbas 1-eaddB Oj SjndU! BlBP a41 Bu,snB::> '19ljj0UB 1au-e auo paIq-eua a1B sa1-e6 1axaId111nw a41 'pa1uawa1::>uI S! 1a1unoo a41 sv ·uo,s1a11uoo I-epas-01-Ia11-e1-ed ·p ·g 1axaId!\lnll'J ·g IB\00 ·v 146p lB 6U!MB1P aas '£ t!O ·p '. 19j1911U! ·o '. ONVN ·q '. tfOX 'B ·c ·s1a11a11u, PUB sa1-e6 AIUO asn s1,n::>l!O IBUO!lBU!qW08 ·asI-e.:1 ·q · l A l'lllL '1988 91 without the necessity to rotate values through 180° to do conversions. The dual coordinate Smith Chart is available in single sheet or in packs of 100. Enquiries should be directed to Stewart Electronic Components Pty Ltd, 44 Stafford Street, Huntingdale, Victoria 3166. Phone (03) 543 7233. 5A variac from Geoff Wood Electronics Wireless adaptor for CD players Many people would like to listen to their portable CD player in their car but do not want to go to the trouble of having the radio's wiring altered so that connections can be made easily. Now there is a product which makes it easy. It is the CDA-1 stereo wireless transmitter which can be connected to the headphone output of your CD player. It then broadcasts a low power stereo signal on about 90.35MHz (adjustable from 89 to 91MHz) which can be picked up on the FM band on your car radio. In fact the CDA-1 can be connected to any stereo appliance which has a stereo 3.5mm jack socket so it can be used to broadcast a stereo signal throughout your home. For example, you could connect it to the headphone output of your CD player (portable or otherwise) and then listen to the signal via an FM stereo Walkman anywhere in your home or even outside. Powered by a single 1.5V AAA cell, the CDA-1 has circuitry to turn it on automatically when audio signal is present and turn it off again when the program ceases. This means that the single cell is conserved as far as possible and you don't have to worry about turning it off. It does have a very small switch on it though, for selecting mono or stereo operation. Recommended retail price is $69.95 from all Arista outlets. Dual coordinate Smith Chart from Stewart Electronics If you're involved in radio frequency or transmission line design you will be familiar with the uses of the Smith Chart (conceived by Philip Smith of Bell Laboratories in the 1930s). Now there is a new version of the chart which has the impedance coordinates printed in red and the admittance coordinates printed in pale green. This will save a lot of time when manipulating admittance and impedance values RCS Radio Pty Ltd is the only company which manufactures and sells every PCB & front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207 Phone (02) 587 3491 for instant prices 4-HOUR TURNAROUND SERVICE 92 SILICON CHIP Every well-equipped workshop needs a decent variable autotransformer (usually referred to as a variac). It is the only way of providing wide mains voltage variations at will. This often needs to be done when circuitry is being designed and serviced. This model from Geoff Wood Electronics is rated at up to five amps and is variable from zero to 105 % of the input. This means that for a 240V AC input it will put out a maximum voltage of just over 250VAC. The variac's output is terminated in twG insulated binding post terminals and a metal screw terminal is provided for earthing. This is OK in strict laboratory conditions but most workshops and labs would fit such a variac with a standard 3-pin mains socket for safer operation. This particular unit has a flat panel which would make it easy to install a surface mount 3-pin AC socket. There is also a large illuminated rocker switch on the variac which is a convenient feature. The price is just $175 which is something of a bargain in today's market. For further information contact Geoff Wood Electronics, 229 Burns Bay Road, Lane Cove NSW 2066. Phone (02) 427 1676. Sony's limited edition Video 8 Camcorder To mark the Australian Bicentenary, Sony has released a limited edition of its Video 8 Camcorder, the model CCD-AU200. This is dressed up in the green and gold Bicentenary colours. The CCD-AU200 uses the standard 8mm Video 8 cassette giving up to three hours of recording time (depending on the battery pack) and has a charge coupled picture sen- The Way I See It - Light sensitive switch for outdoor lighting If you wish to turn a light on at dusk and off at dawn this unit from Arista is the solution. It combines a bimetal switch and large photocell to provide automatic switching. It is energised from 240V AC by connecting it in series with the lamp to be switched. It is rated for incandescent lamp loads up to 2kW; up to lkW for mercury discharge lamps with high power factor; and up to 1.8kW on mercury discharge lamps with low power factor. Power dissipation in the switch itself is two watts. It is claimed to switch on for light levels below 20 lux and off for light levels above 100 lux. The NLS2 light sensitive sor which will operate down to a minimum light level of 19 lux. The camera has automtic white balance, automatic iris and automatic focus so that picture recording is just a matter of aiming and squeezing the trigger. In addition to these features, the camera has a manual zoom lens (2.5x) with macro capability for close-ups. It also has compensation for backlighting which normally ctd from page 19 power output four times as high as the continuous power rating. Now we are starting to talk about a really worthwhile increase in power, or are we? Designing an amplifier with such a headroom figure means that the power supply and heatsink requirements are quite different from those for an amplifier expressly designed to meet FTC standards. Instead of having a power supply which is comparatively well regulated (ie, varying in voltage between no signal and full power by only 10% or less), we have a power supply which is designed to deliver maximum output for a very short period of time which under the IHF standards is only 20 milliseconds. That means you can use a small power transformer and still come up with spectacular power outputs. For example, with a power transformer, output transistor and heatsink configuration which might normally be expected to give 50 watts per channel, you could now get 200 watts per channel but only on very short term basis. This is just what you want for handling those short term transients which characterise pianos, guitars and other percussive instruments. That is just what a number of manufacturers have done. By various means, companies like Carver, NAD and Proton have come up with very large figures for music power and headroom. And therein lies the basis for what I described at the outset as a supportable reason for an apparent about-face, and a totally new switch is available at the recommended retail price of $17.95 from Arista outlets. tends to darken the subject; just push the back-light control to correct the picture. The versatile black and white electronic viewfinder has indicators for function and lighting conditions and is adjustable to suit left-handed or right-handed operation. Again, to mark the Bicentenary, the CCD-AU200 is priced at $1988. (Get it?) respectability for once-maligned music power. But, having thus completed one ride on the technical merry-go-round, we find ourselves heading for another, this time to do with the watts/decibels dilemma of the 1930s. What's the best way to describe and rate this extra output? The options are "music power" or "dynamic power" in watts, hopefully supported by the endorsement [IHF-A-202). Or, again, "headroom" in decibels, arrived at by similar methodology. As it happens, the manufacturers in question are specifying both music power and headroom but the tendency is to emphasise the watts and forget the headroom. The way I see it, we still prefer the watts we can boast about to the decibels we can actually hear! lb Al'lllL 1988 93 ASK SIUCON CHIP Got a technical problem? Can't understand a piece of jargon or some electronic principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. How to stretch pulse widths I wish to run two clock oscillators in synchronism. As both are in separate devices, they may only be calibrated every 24 hours. Each is required to pulse at lkHz. The pulse width is not important as it drives a flipflop. I know electronics has evolved to magical heights but just how accurate can they be constructed without the need of a sync pulse or suitcase size "black box". My Seiko watch is highly accurate and in fact triggered this question. A second question is: could a pulse be multiplied in pulse width by a fixed amount regardless of the input pulse width. For example if you had a train of 10 nanosecond pulses, could they be converted to a train of one microsecond pulses; ie, a pulse width multiplication of 100? Similarly, could a train of 0.5µs pulses be converted to 50µs pulses? (M.R., Blackheath, NSW). • Your first question is relatively easy to answer since it is already common practice. What you require is a means of synchronising two physically separate oscillators. In essence, this is no different from the process whereby the local oscillator in an FM tuner is locked to the incoming frequency or the sweep circuits in a TV receiver are locked to the incoming transmission. Having said that, we can only answer your question in general terms. What you need to do is to feed one oscillator to a low power transmitter which could be along similar lines to the UHF remote transmitter described on page 27 of our March 1988 issue. You could use a receiver to suit (same article in last month's issue) and then feed the detected clock signal to a phase lock loop circuit. One of these was used in the ACS Adaptor circuit published in our January 1988 94 SILICON CHIP +sv----------2.2k Fig.1: this simple circuit can be used to stretch pulses by a factor of 100, as set by the ratio of the 100krl and 1kfl timing resistors. IC1 is an LM339 op amp wired as a comparator. issue. From there it would a straightforward matter to lock the two oscillators together. Your second question is more difficult to answer and we had to think for a while to see if it could be done at all. It appears it can although such circuits are more often ref erred to as "pulse stretchers". One point which must be taken into account in such a scheme is the duty cycle. For example, if you have a pulse train with a duty cycle of 5% and a repetition rate of lOkHz (giving a pulse width of 5µs), you cannot apply a pulse stretch of more than, say, 19.50 times. This is because a pulse multiplication of 19.5 would give a duty cycle of 97.5%. So if you wanted to convert 0.5µs pulses to 50µs pulses, the repetition rate could be no more than, say, 19.BkHz. This would give a duty cycle of 99%; ie, the pulse output would be high 99 % of the time. Within that constraint, it is possible to multiply the length of a pulse using the accompanying circuit. It can multiply pulse width although its range is rather limited. It could be expected to operate for input pulses between lOOns and lµs and extend the pulse by about 100. The output pulses would be inverted compared to the input pulses but this could be corrected by a further inverter stage. The circuit operates by charging up a capacitor via a diode and lkO resistor. The charge on the capacitor is dependent upon the length of the input pulse. The output of the LM339 comparator goes low and remains low until the capacitor discharges which is made lOOx longer than the charge time by using a lOOkO resistor. We haven't tried this circuit by the way but the principle seems .sound enough. A more precise way of achieving the same result could probably be achieved using digital circuitry but we'll leave that for the fertile minds of our readers. If they can come up with a better way, we'll publish it in our Circuit Notebook pages. Lubrication of small shaded pole motors This story of what is believed to be a fairly common fault with 240V AC shaded pole motors, although not always recognised, may be of interest. I refer to any shaded pole motor fitted with socalled lifetime lubricated bearings. A Uher 2000 Report portable recorder, which we had for many years, became a reluctant starter, although once started, its speed was spot-on. No reason could be found for this and the machine was sidelined for a considerable time. The solution to the problem was found in a very comprehensive general service manual published in the USA. So-called lifetime lubricated bearings are usually graphite impregnated bronze or brass material, or porous bronze or brass which is soaked in a special oil prior to being fitted to the machine. The first relies on the graphite for lubrication and is never oiled, even initially. The second, using porous metal, was reckoned to have soaked up enough oil in its initial oiling to last the lifetime of the machine. What this neglects is that all oil oxidises and becomes gummy and that is what happened to our Uher machine. I oiled it by feeding the correct oil drop by drop through a hyperdermic needle to the two top bearings and to the two on the idler shaft. The motor now starts every time without hesitation. I used Shell Tellus 40 oil although that may not be available now. (A.S., Barcaldine, NSW). • Dry or gummed bearings were briefly mentioned in last month's article on repairing radio-cassette players but your comments amplify the topic. Thanks for the tip. Wants dual gang 2-Megohm pot I have a Plessey Ducan stereo amplifier about 15 years old which satisfies my needs. I am having trouble with the 2MO volume control whereby one channel drops out at certain settings of the control. Several electronics stores have informed me that 2MO pots are no longer available. Can you please advise if the input circuit could be modified to use a lower value pot? (D.C., Mulgrave, Victoria). • Here we go again. "No longer made" is the easy way out. The fact is that demand for such pots is probably now at such a low level that it is not worthwhile for these stores to stock this value but we have no doubt that such pots are still being made. After all, cheap record players with ceramic cartridges are still being made and they still need high value pots. We are sure that if anybody was to place a large orde r for 2MO pots with a Power amplifiers & electrostatic speakers I have a number of questions, the first concerning your amplifier described in the December and February issues. I know Altronics makes it available as a complete unit but I just want the circuit boards. I would like to build it for an active loudspeaker project with a cost-no-object selection of components. From whom are they available and at what price? Can we expect amplifiers in the future in the 350 to 500 watts/channel range with possibly greater sophistication such as anti-thump turn-on, DC servo feedback and relay speaker protection. Is there a project for a matching preamplifier for the 100 100W amplifier. An AM/FM stereo tuner perhaps? The last topic I would like to talk about is loudspeakers. There have been plenty of speaker projects published over the years but never an electrostatic. I've heard that they aren't that hard to build, so what about it? Incidentally, I built your UHF antenna. Excellent! (B.C., address not supplied). • Printed circuit boards for all SILICON CHIP projects are available from RCS Radio Pty Ltd, 651 Forest Road, Bexley, distributor or manufacturer these pots would suddenly be available. To answer your question though, yes, you can substitute a lMO dual gang pot for the 2MO unit. However, you may find that this results in some loss of bass. The solution to this problem, provided you have signal to spare, is to shunt the potentiometer with a capacitor of lOOpF or thereabouts. This reduces the apparent reactive impedance of the cartridge and allows a more extended bass response although signal is sacrificed. Material substitution for UHF antenna I am interested in building the UHF bow-tie array featured in your NSW (phone (02) 587 3491); or Jemal Products Pty Ltd, 5 Forge Street, Kewdale, WA (phone (09) 451 8726). We will be constantly looking at the economies of producing higher power amplifiers but for the moment, they are very expensive. We'd be wary of such a project unless there was a big demand for it. We are planning to publish a stereo control unit for the Studio 200 power amplifier very soon, and are working on the project right now. In principle, electrostatics are delightfully simple and more than one overseas magazine has published information on building you own. But we think that fiddling around with Mylar film would be very tricky. The transformer would not be easy either. It is no simple matter to make a transformer with a large step-up ratio (more than 60: 1 required) which also has a flat frequency response, within say ± 2dB from 50Hz to 20kHz. Such a high quality, high voltage transformer might cost $150 or a lot more. On the other hand, the· transformer would really be the only expensive component so perhaps we should have a much closer look at the viability of such a project. January issue but I have not been able to purchase 6mm aluminium tubing. I've tried everywhere and the smallest diameter tubing available is 10mm. Is this suitable? (D.F., Concord, NSW). • We have had quite a few readers phone us with the same problem, so you're not alone. For the record, we purchased all our aluminium for the project from the Alcan Aluminium Centre at Manly Vale in Sydney. 10mm tubing will work but it will present a lot more windage than 6mm tube. It would be better to use 0.25-inch solid aluminium rod. We understand that this is more readily available although, since aluminium is sold by weight, it is likely to be a little more expensive. le A l'll!L"HJ88 95 T CEli'I' Cash in your surplus gear. Advertise it here in Silicon Chip. 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). 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 own classified ad, put one word on each of the lines below and send this form with your payment to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach , NSW 2097. PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ($7.00) 16 ($7.40) 17 ($7.80) 18 ($8.20) 19 ($8.60) 20 ($9.00) 21 ($9.40) 22 ($9.80) 23 ($10.20) 24 ($10.60) 25 ($11.00) Name ....... .. .... .... ..... .......... ..... ......... .. .. ........ .. .. .. .. .. ........ ..... .... ..... ...... .......... ... ...... . Address .. .. .... ... ... .. ... .. .. ....... ........... .. ... ..... ..... ....... ..... .......... .... ..... ........ ..... .. .... ..... . Suburb/Town .. .. .. .. . .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. Postcode ........ .. Enclosed is my cneque or money order for$ ........ ... .... .. .. ........ .......... or please debit my Bankcard □ Visa □ Advertisers Index Our advertisers are vital to the success of SILICON CHIP. Please give them your support. Altronics .. .. ................ .... 70-73 Arista Electronics .............. .. . 1 9 Avtek ................................ IBC Dick Smith Electronics .... 52 ,53, 84 ,85 Elmeasco .. ..... .. ......... ....... . IFC Geoff Wood Electronics ... 41 -4 7 Jaycar Electronics .......... 20-27 Kenwood Australia ..... ....... OBC RCS Radio .......................... 92 Rod Irving Electronics .. .... ..... .. 9 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd , 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. • Jemal Products, 5 Forge St, Kewd.ale, WA 6105 . Phone (09) 451 8726 . Card No ...... ....... .... .... .... ... ..... ... .. ..... .... ..... ........ .... ...... ..... ....... ..... ..... .. . Signature ..... .... .. .. .... ..... ............ .... ....... ................ ....... ... .... ..... .. .... ......... ............. . FOR SALE NEARLY 1500 PRINTER buffer kits now sold. Prices start at $39 for a 256K short form kit. All items advertised are in stock. Dealer enquiries welcome . Bulk discounts. Schools, Govt. Depts. orders accepted. Oh yes!! IBM compatible . Australian designed and manufactured. Ideal project for user groups or students. For a free catalog send a 37c stamp to : Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. SHACK CLEAROUT . R1000 Kenwood Receiver with box and instructions. As new- $300 . HX 2000 Regency scan ner $200; Ranger AR3300 HF transceiver, 26-30MHz, 25W PEP, AM-SSB-CW-FM, $250; Marconi signal generator TF995 with spares $100; 2 x UHF CB Uniden Sundowner with CTCSS modules fitted , $200 each; 9dB base station antenna $90; 6dB base station antenna $60; Ratcliff 96 SILI CON Cl-Ill' signal generator Model 205 (45 - 180MHz) $50. All prices negotiable. Ring (02) 487 1439 after 8pm evenings and weekends . Garry VK2YBX. FOR SALE: ETI SERIES 5000 preamplifier, $320. 1/3-octave graphic equalisers, $160 each . Phone (02) 542 3628 after 5pm . Amateur Radio continued from page 69 which is wrapped around the top of the loading coil. Figs.1 & 2 show the details. This construction technique must be followed exactly, otherwise the resonant frequency will be other than that which is desired. In any case, a GDO (grid dip oscillator) should be used to verify the correct frequency of operation, after the antenna is mounted on the vehicle. After the coil has been wound .and the coupling "capacitor" installed, the PVC shroud can be glued in place and the top of the coil soldered to the top metal fitting. As the 1/2-wave whip mounting technique is quite strong, it is suitable for either VHF or UHF antennas. ~ Negative Feedback continued from page 14 pected to have the theory as a set of differential equations. Let's leave our young enthusiasts before they get too far ahead of us. Clearly they must be the brightest building site observers ever. One point is clear though. When they have fully developed their theory of feedback systems, it will be a truly general set of equations. Next month, we will show you more of this fascinating stuff, but we will naturally accent the electronic side of this beaut story. And we will be very down-to-earth and practical to boot. ~ M O D E M S fo7. cflu~hafia Don't buy imported unsupported The Avtek advantage• Australian designed Australian manufactured Australian supported MEGAMODEMS 12/123 The Avtek Megamodems provide Australia's best value communications products, with a range of fully automatic, autodialling modems. Megamodems are suitable for data transfer from personal computers, terminals, mainframes and mini host computers and for all videotex services such as Viatel. The use of the latest technology has enabled us to make the Megamodem more compact and reliable than any other modem. Price is very competitive and reflects efficiencies incorporated in the design. The Megamodems are locally designed and built. Service, support and specialist R&D for the Megamodem range is all based in Australia. Available either as a standalone RS232 model or as a plug in l/2 card for IBM PCs and compatibles. The Megamodem range of modems are Telecom authorised. Specifications Data Standards Data Rates MAIL ORDER WELCOME VISA Automatic Dial, Answer, and Disconnect: The Megamodems will automatically answer an incoming call and connect the computer to the line. When originating a call it will then dial out the required number and auto-connect to the computer at the other end. It will then "hang-up" at the end of a communications session. Both pulse and tone dialling are supported. The modem is compatible with new Telecom exchanges and modern PABXs and can handle high speed tone dialling. Fully Hayes AT Smartmodem Compatible: The Megamodems are industry standard "HAYESSMARTMODEM "compatible which means they can take advantage of all the communications facilities of packages such as Crosstalk, Open Access, Symphony and Multicom. All communications parameters such as baud rate, parity and number of stop bits are set up automatically by the software and the Megamodem. Using appropriate software data can be sent and received while the Megamodem is unattended. CCITTV27, Bell 103, CCITT V22 Bell 212. (123 model only CCITT V23) 300/300, 1200/1200 (123 model only 1200/75, 75/ 1200) BUY DIRECT FROM THE MANUFACTURER Model 12 & PC12 $375 nctax Model 123 & PC123 $449nctax ~=-~ yTr1( £:;~. ~ I~~ [ ·I 1 1 PO Box 651 Lane Cove 2066 Telephone (02) 427 2177 Facsimile (02) 428 2995