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August 2000  1 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.circuitmaker.com Contents FEATURES 4 Drive By Wire: Electronic Throttle Control; Pt.1 The direct link between the driver’s foot and the throttle position is about to be broken – by Julian Edgar Vol.13, No.8; August 2000 CircuitMaker 2000 Virtual Electronics Lab – Page 26. 26 Review: CircuitMaker 2000 Virtual Electronics Lab A versatile circuit design and simulation package – by Peter Smith 70 Structured Cabling & the Krone MiniLAN Changing your network cabling doesn’t have to be a hassle. With a Krone MiniLAN system, it’s as easy as 1-2-3! – by Ross Tester PROJECTS TO BUILD 16 Build A Theremin For Really Eerie Sounds You wave your hands around mysteriously to play it – by John Clarke 32 Come In Spinner No, it’s not our version of Two-Up! Instead, you spin it and it writes messages in thin air – by Atilla Aknar & Ross Tester 54 Loudspeaker Protector And Fan Controller Install it in the Ultra-LD Amplifier and protect your speakers against output stage faults. The fan control is a bonus – by Peter Smith & Leo Simpson Come In Spinner – Page 32. 62 Proximity Switch For 240VAC Lamps Just wave your hand near it to turn the light on or off – by Leo Simpson SPECIAL COLUMNS 38 Serviceman’s Log It doesn’t pay to be too smug – by the TV Serviceman 84 Vintage Radio The Astor RQ Lady’s Handbag Radio – by Rodney Champness Loudspeaker Protector And Fan Controller – Page 54. DEPARTMENTS 2 25 53 78 80 Publisher’s Letter Mailbag Subscriptions Form Circuit Notebook Product Showcase 89 91 83 94 96 Ask Silicon Chip Notes & Errata Electronics Showcase Market Centre Advertising Index Proximity Switch for 240VAC Lamps – Page 62 August 2000  1 PUBLISHER’S LETTER www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Peter Smith Ross Tester Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Rick Winkler Phone (02) 9979 5644 Fax (02) 9979 6503 Mobile: 0414 34 6669 Regular Contributors Brendan Akhurst Louis Challis Rodney Champness Garry Cratt, VK2YBX Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Philip Watson, MIREE, VK2ZPW Bob Young SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490 All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $69.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip Don’t wait for digital broadcasts if buying a new TV set One of the questions we are often asked at SILICON CHIP concerns digital broadcasting and whether it is worth waiting to buy a digital TV receiver. Often the person concerned has a relatively old TV set, maybe 10 years old or more, and is looking for an excuse to upgrade to a new set. But with all the puff about digital TV at the moment there are doubts. Supposedly, digital TV will be so much better than present-day broadcasts and people do not want to be caught with a newish but obsolete set. The short answer to these questions is to go out and buy a new set, if that’s what you want. If you do, you will get the immediate benefit of a new set - a much brighter and sharper picture and at a price that is not likely to reduce in the short term now that GST is in force. Perhaps you still have doubts. If so, perhaps I can dispel them. First, if you do not intend buying a large screen set, say 80cm or larger, there is little point in worrying about whether you will get a better picture when digital broadcasting comes in. With the smaller screen sizes, it is just not possible for the average viewer to discern any improvement in picture quality, even if you had high definition broadcasts. Perhaps I should qualify that. If you are comparing the picture quality with good ghost free reception and studio broadcasts or DVD playback on a 68cm or smaller set, there will be very little, if any, improve­ment when digital broadcasting comes in. If you can afford it, you should seriously consider buying an 80cm or larger set because that’s where the real developments are happening and where prices are dropping the most. For exam­ple, it is now possible to purchase an 80cm Teac set for as little as $1499. Not comfortable with a low-cost brand? Then what about a Philips or Panasonic 80cm set for under $2000? Not only can you get features such as picture-in-picture and NTSC playback, you can also expect “component video” inputs which are desirable for the very best picture quality from DVD players. Alternatively, you might decide to go for one of the larger rear projection sets and here you really do get a large screen for quite reasonable amounts of money. Well, OK, for many people $3500 or more is not a reasonable amount of money but it is a good deal less than you would have paid a few years ago. And some of the new rear projection sets are now coming out with ghost-free line-doubling (100Hz horizontal scan rate for flicker-free pictures) and pixel doubling as well. When digital broadcasting does come in, you can expect the new digital TV receivers to be a great deal more expensive and most people will opt for a set-top converter. But even then, if we follow overseas experience, such set-top converters will be available as part of the deal from Pay-TV companies and they look like having more features such as multi-cameras and so on. So if you are thinking of buying a new set, there is not much reason to hold back. Go out and buy it. Remember, the price of a new TV set will be the cheapest entertainment you will ever buy. Leo Simpson    Internet Router SmartMedia Reader/Writer *Affordable Web-Based Training When smaller internet A whole range of courses are available! Including access servers just won’t WIN 2000, Lotus Notes R5, Home Business, handle the complexities of Motivation, Internet Information Server 4 and your office communications, our routers may just Microsoft Certified Systems Engineer Series. do the job. For example: *Full details at www.tol.com.au • Dial into your network from the internet • Dial-in remote configuration The controller provides RAID Level 1 disk mirroring. • Security callback HDD Hot Swap IDE RAID Disk Array Cat. 2808 $1176 • Optional radius authentication HDD IDE RAID Array - Spare Frame Cat. 2812 $80.50 • LAN to LAN routing Network tester with LCD Display • Up to four In/Out modem ports An intelligent continuity tester for • Excellent tutorial style manuals LAN cables that saves time on Cat. 10110 Internet Router 5 LAN 2 WAN $649 Cat. 10111 Internet Router 1 LAN 4 WAN $930 the job. It tests a range of Modular cables including 5 Port 10/100M Fast Ethernet Switch 10Base-T (Category 3-5). The This 5-port Fast Ethernet switch enables even the LCD display shows the pin connections as well as the wiring most budget-conscious scheme detected. organizations to trade up to the next level of networking power. It supports 10/100Mbps auto-negotiation on all ports, for seamless migration to 100Mbps connections without time-consuming trips to the wiring closet whenever end stations are upgraded to Fast Ethernet. All ports also automatically sense half or full duplex connections for high speed server or switch-toswitch configurations. Cat. 11333 Cat. 11334 Five Port Desktop 10/100Mbps Hub Eight Port Desktop 10/100Mbps Hub $172 $220 External Case for 3.5” IDE via FireWire Cat. 11519 Network Tester with LCD PS/2 Keyboard & Mouse Adapter Turns your laptop into a desktop with a single, pocket size adapter. It allows the use of a keyboard and a mouse from a single port! Cat. 15093 Cat. 15094 A SmartMedia (as used with digital cameras) reader/writer which connects to a parallel port to allow fast transfer of photos to your computer. The reader appears as another drive on your PC, just use Windows Explorer to copy the files. SmartMedia Reader/Writer PCMCIA & Compact Flash Reader/Writer Parallel Port PCMCIA & Compact Flash Reader/Writer USB Cat. 6603 Cat. 6457 Cat. 6489 External Case for 3.5” IDE via FireWire FireWire to PCI Host Adapter $376 $197 $169 $140 Dual Mouse Adapters Use 2 Pointing Devices from 1 PC ! Left & right handed mice, trackballs, touch pads, etc. Each has its strengths. Now you can maximize your computing experience by connecting your two favourites and switching instantly between them as you work. Choose between PS/2 and serial connection models. Hot-Swap IDE RAID Array Avoid downtime delays when your hard drive fails! You can replace the hard disk while the PC is operating and the unit automatically resynchronizes itself to full operation. The RAID unit fits into two continuous 5.25" bays and includes a controller and two removable frames. The array accepts two EIDE, Ultra DMA 66/33 or PIO 4 hard drives. Cat. 15091 Dual PS/2 Keyboard Adapter $111 Dual Monitor Adapter Smart Card / Mag Card Reader- OEM Smart Card Reader / Writer - Serial Dual Monitor Adapter $689 $160 PCMCIA to FireWire Converter High performance Cardbus to Firewire adapter for MAC, Windows SE98 & Win 2000 only. Cardbus is the 32 bit version of the PCMCIA interface, which is 16 bit. Connect DV Camcorders, DV Corders, CCD cameras & Professional Digital still image cameras etc to your Notebook. It will support up to 63 IEEE1394 FireWire devices and provides a true high performance I/O solution for users that are demanding IEEE1394 consumer & professional devices. Upgrade software* is available at time of purchase. Cat. 70406 PCMCIA to FireWire FireWire & USB Combo Card FireWire to PCI Host Adapter *MediaStudioPro V6.0 VE $312 $281 $197 $140 2 Port USB PCMCIA Card No USB Port on your Notebook PC? Just slide this PC Card into your notebook and, instantly, you can begin connecting USB peripherals. NO complex installation, confusing plug-ins, or IRQs. PC Card enables any Notebook PC with Card Bus Slot to connect USB products. The best way to attach two monitors to one computer. Not only does this adapter split the (S)VGA video signal, it boosts it for optimum image quality. It will support resolutions up to 1280 x 1024 and up to 32-bit color (4 billion colors). Perfect for presentations - use one monitor for the preTwo Port USB PCMCIA Card Cat. 2810 senter and the other for the audience. Prices may vary with exchange rates Cat. 15092 $187 Ideal for a wide range of applications, including vending machines, gaming, ATM transactions, security access system, electronic wallet systems & customer data management systems. It uses a ddm 862-hybrid card acceptor that has one push-pull $187 magnetic card reader & one chip card connector. The unit comes standard with one User IC Card & 3 SAM card acceptors. The magnetic card reader is standard with dual track 2/3. Need FAST access to an external hard drive? Just fit a standard 3.5in IDE Hard Drive to this case and connect it to a FireWire port (See Cat. 2621). Drive Cat. 15090 Dual PS/2 Mouse Adapter $111 Dual Serial Mouse Adapter $111 capacity may be up to 128GB. Data transfer rate Cat. 15097 is 400Mbps (IEEE 1394) and it supports Hot Dual Keyboard Adapter Cat. 2821 Swapping and plug-and-play. It is suitable for PC’s Need input from two locations or need a specialized and Cat. 2823 with Win98 SE or Win2000 only. Cat. 2621 standard keyboard? Here is the answer! Cat. 6633 Cat. 2621 $218 Smart Card / Magnetic Card Reader Cat. 8901 Cat. 8899 PS/2 Keyboard & Mouse Adapter USB Keyboard & Mouse Adapter $263 $216 E & OE $180 All prices include sales tax MICROGRAM 0800 Come and visit our online catalogue & shop at www.mgram.com.au Phone: (02) 4389 8444 Dealer Enquiries Welcome sales<at>mgram.com.au info<at>mgram.com.au Australia-Wide Express Courier (To 3kg) $10 FreeFax 1 800 625 777 We welcome Bankcard Mastercard VISA Unit 1, 14 Bon Mace Close, Berkeley Vale NSW 2261 Vamtest Pty Ltd trading as MicroGram Computers ABN 60 003 062 100 Fax: (02) 4389 8388 Web site: www.mgram.com.au FreeFax 1 800 625 777 August 2000  3 Drive By Wire The Bosch ME-Motronic System; Pt.1 The Bosch ME-Motronic system is the first “drive-by-wire” engine management system for cars. It breaks the direct link between the driver’s foot and the throttle position and it’s coming soon to your new car. By JULIAN EDGAR The new Bosch ME-Motronic system takes a radically differ­ ent approach to engine management systems. There is no accelera­tor cable. While it initially appears to have all the usual ingredients of a modern electronic management system – fuel injectors, input sensors, an electronic control unit (ECU) and so on – the use of accelerator position sensing and an electronic throt­tle actuator makes this system very different. In effect, the direct link between the driver’s foot and the throttle is broken. What the driver demands may not be what the driver gets. This situation has existed on some large trucks for some time now. However, it’s only now that the engine management 4  Silicon Chip system has be able to adjust the relationship between the car’s accelerator pedal and throttle opening. Not only can this system control fuel injection and ignition but also the cylinder charge. Making the advent of the ME-Motronic even more of a sea change is the underlying operating logic. Unlike other engine management systems, ME-Motronic determines how much engine torque is required in any given situation and then opens the throttle sufficiently to allow the engine to develop that much torque. The accelerator pedal travel becomes just the driver’s “torque request”, to be weighed up against other torque requests generated by the traction control system, speed limiter, engine braking torque control and others. Furthermore, at all times the engine management ECU models the engine’s instantaneous torque development, adjusting the throttle opening according to the relationship between the requested and developed torque. A quick example makes this easier to understand. In some situations, the driver may have only depressed the accelerator pedal halfway – but under the bonnet, the throttle butterfly valve can have snapped wide open! But why would this be an advan­tage? In turbo-charged cars, the maximum available torque can vary substantially over quite a narrow range of engine speed. For example, the current model Audi S4 twin turbo V6 develops a maximum torque of 300Nm at 1400 RPM and 400Nm at 1850 RPM. So, across just 450 RPM of engine speed, the peak torque varies by 33%. This characteristic is caused by the two turbos rapidly increasing in speed – ie, “coming on boost”. Fig.1 shows the power and torque curves for this particular engine; a similarly shaped torque curve is as- Fig.1: the torque curve of this twin turbo Audi 2.67 litre V6 shows the very rapid rise that occurs as the turbos start to boost at low engine speeds. Electronic throttle control by the Bosch ME-Motronic 7.1 engine management system allows good driveability, even with this massive torque change. [Audi] sociated to a greater or lesser degree with all turbo-charged engines. A driver of a turbo car equipped with traditional engine management tends to automatically compensate for this steeply rising torque curve. When wishing to accelerate moderately hard, he or she will initially floor the throttle and then back off as turbo boost and torque rises. But with the latest Audi S4 V6, equipped Where there are major torque changes over a small range in engine speeds, an engine management system that varies the relationship between accelerator position and throttle opening can yield major improvements in driveability. This Audi twin turbo V6 – fitted to the current S4 model – uses Bosch ME-Motronic management. The 2000 model Porsche on the facing page is also fitted with the Bosch ME-Motronic system. with Bosch ME 7.1, the driver need not do this. At low speeds when the engine response is relatively poor – the turbos yet to generate appreciable boost – the ME-Motronic system opens the throttle far further than the driver pushes the pedal and then as revs rise, it au- tomatically adjusts the throt­tle angle to retain a smooth linear response. In this way, drive­ability, emissions and fuel consumption are all improved. Inputs and outputs As indicated, at first glance the ME-Motronic system looks very Fig.2: The ME-Motronic system has inputs and outputs very similar to other engine management systems but it has two unique items – the accelerator pedal travel input sensor and the ETC (Electronic Throttle Control) actuator. [Bosch] August 2000  5 RESISTANCE IN OHMS RESISTANCE IN OHMS THROTTLE VALVE OPENING IN % ACCELERATOR TRAVEL Fig.3: two potentiometers are used in the accelerator position sensor (to give redundancy) and they are slightly offset to give characteristic shown here. [Audi] similar to other current management systems. Fig.2 shows the inputs and outputs of a typical ME-Motronic system. In addition to two-way diagnostics and Controller Area Network buses (the CAN buses communicate with other systems such as the automatic trans­mission ECU), the inputs comprise: • Vehicle speed; • Transmission gear; • Camshaft position; • Crankshaft speed and position; • Dual oxygen sensors (located eith­ er side of the catalytic converter – ‘V’ engines have four sensors); • Knock sensor; • Coolant temperature; • Intake air temperature sensor; • Battery voltage; • Intake air mass (plus frequently manifold pressure); • Throttle position. None of these inputs is unique to this system but it also includes a sensor for accelerator pedal position. Fig.4: the feedback mechanism of the throttle – which shows the actual throttle valve position – also uses two potentiometers. However, these have output character­ istics that work in opposite directions. [Audi] With one exception, the outputs are also very similar to other recent management systems: • Spark plugs; • Injectors; • Instrument panel tachometer; • Fuel pump relay; • Oxygen sensor heaters; • Intake manifold runner control (ie control of the position of valves within dual tuned length manifolds, or the length of infinitely variable intake runners); • Fuel system evaporative control, secondary air injection and exhaust gas recirculation (all emissions control approaches). The added component is the Electronic throttle control actuator. Let’s have a look at these two extra components in more detail. Accelerator position sensor Two approaches are currently used in the design of this sensor but they are electrically identical. Movement Fig.5: the Accelerator Pedal Position Sensor uses a dual poten­tiometer connected to the accelerator pedal by a rod and crank. [Audi] 6  Silicon Chip of the accelerator pedal rotates two potentiometers; as already noted, there is no Bowden cable to connect accelerator pedal movement to the throttle butterfly. Two potentiometers are fitted to the sensor to allow redundancy – if one fails, the other still lets the system operate. As shown in Fig.3, the outputs of the potentiometers are identical but for an offset. Cars equipped with automatic trans­missions do not have an additional kickdown switch in the assem­bly. Instead, a ‘mechanical pressure point’ is used to give the feel of a kickdown switch. Fig.5 shows the pedal assembly and sensor used in the Audi S4. If the accelerator position sensor fails, the lack of any mechanical connection between the accelerator and the throttle means that ‘limp home’ techniques are called for. The Audi S4 has two: Emergency running program 1: this occurs when a single accelerator position potentiome­ter fails. In this case, the throttle position is limited to a defined value. In the case of implausible signals from the two potentiometers, the lower value of the two is used. At the same time, the brake light signal is used to switch the engine back to idling and the fault lamp is illuminated. Emergency running program 2: this occurs when both accelerator position potentiometers fail. This more drastic condition causes the engine to run only at idle speed and the fault lamp is illuminated. Interestingly, in the Audi, if the accelerator and brake pedals are depressed together, the throttle valve is automatical­ly closed to a defined small opening. However, if the brake is pressed and depressing of the ac- celerator then follows this, the torque request is enabled. I assume that the latter provision is solely for those who like to left-foot brake, with applications of power used to balance the car! Throttle control actuator The electronic throttle valve consists of a DC motor, reduction gear drive and dual feedback angle sensors. Again to provide redundancy, two potentiometers are used for angle feed­ back. However, unlike the accelerator position sensor, these sensors have opposite resistance characteristics to one another, as shown in Fig.4. While continuous sensing of the throttle butterfly valve position does occur, the ECU only recognises four key functional positions of the throttle: • Lower mechanical limit stop – the valve is totally shut. • Lower electrical limit stop – the lower limit used in normal operation. This position does not totally close the valve, thus preventing contact wear of the housing and throttle blade. • Emergency running position – the position of the valve when it is not energised. This allows sufficient airflow for an idle speed a little higher than standard. • Upper electrical limit stop – the valve is fully open. The control system has a learning function, whereby the state of the mechanicals within the electronic throttle (eg, spring tensions) is determined by the evaluation of the throttle valve’s reaction speed. Fig.6 shows an internal view of the Electronic Throttle Control Actuator. As with the Accelerator Pedal Position Sensor, limp-home techniques are available should the Electronic Throttle Control Actuator develop problems. These include: Emergency running program 1: this occurs when an angle sensor within the throttle body fails or an implausible signal is received. The program still requires a throttle angle signal and a plausible mass airflow measurement. Torque increasing requests from other systems are ignored (eg, from the Engine Braking Control) and the fault lamp is illuminated. Emergency running program 2: this occurs if the throttle valve drive fails or malfunc­tions; it requires that both throttle valve potentiometers recog­ nise the Emergency Running Position Fig.6: The throttle valve is moved by means of a reversible DC motor acting through a reduction drive. In the event of failure, the valve defaults to a nearclosed position. [Audi] of the throttle blade. The throttle valve drive is switched off so that the valve defaults to the small emergency running opening. As far as possi­ble, ignition angle control and turbo boost control(!) are used to execute the driver torque demands. Finally, the fault lamp is illuminated as before. Emergency running program 3: this occurs if the throttle valve position is unknown and/or if the throttle valve is not definitely known to be in the Emergency Running Position. The throttle valve drive is switched off so that the valve (hopefully!) de- faults to the small emergen­cy running opening. The engine speed is limited to approximately 1200 RPM by fuel injection control and the fault lamp is illumi­nated. A schematic diagram showing the operation of the electronic throttle system is shown in Fig.7. As you can see, Bosch engineers have been very careful to ensure that a failure of the electronic throttle system will not cause the engine to suddenly have full power or to stall. Next month, we’ll take a look at the operating logic of the ME-Motronic SC system. ENGINE CONTROL UNIT INPUT SIGNALS THROTTLE VALVE DRIVE OUTPUT SIGNALS ACCELERATOR POSITION SENDER M CPU ACCELERATOR POSITION SENDERS SAFETY MODULE ANGLE SENDER FOR THROTTLE VALVE DRIVE Fig.7: the Bosch ME electronic throttle control system. Dual (redundant) potentiometers are used in both the accelerator position sensor and for the throttle angle feedback sensor. [Audi] August 2000  7 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au n i m e r e h T Get the eerie soaring sounds of science fiction You wave your hands around mysteriously to play it 16  Silicon Chip Producing sounds with the slightest of hand gestures, the Theremin is the fore­runner of modern synthesised music. You can create eerie science fiction movie sounds or make melodious music simply by hand movements. By JOHN CLARKE T HE THEREMIN WAS invented by Leon Theremin of Lenin grad, Russia in 1924 and it represented a revolutionary change in thinking about how music could be produced, challenging tradi­tional stringed, brass and percussion musical instruments. Comprising electronic oscillators, it allowed control over both pitch and amplitude by moving the hands over sensor plates. Its design eventually led to the development of the Moog Synthe­ siser and electronically synthesised music in general. But the invention was not only instrumental in the develop­ment of electronic music, it also had an impact on a free-form style of playing music. The free gesture hand control afforded by the Theremin pre-empted the modern Sensor Chair synthesiser controller where the whole body is a part of the musical genera­tion process. Before this, Jimi Hendrix was creating new sounds by gener­ ating feedback between his guitar and the amplified sound and then moving his body to modulate the amplitude. It freed him from the restriction of generating music solely by plucking the guitar strings. The Theremin was commercially manufactured by the Radio-victor Corporation of America (RCA) around 1929. It comprised a large box to which were attached an antenna and wire loop. The antenna provided the control for the pitch while the loop enabled the volume to be adjusted. Moving the right hand toward the antenna would reduce the pitch while moving the hand away from the antenna would increase the pitch. In some ways this is similar to playing a trombone whereby the slide is moved back and forth to vary the pitch. The left hand would reduce the volume as it was brought near the sensor loop. As you would expect, the original Theremin circuit used valves. The pitch control antenna stood vertically, while the volume loop sat horizontally. This meant that there was little interaction between the two controls especially since the pitch control hand would be held side on to the antenna and the volume control hand would be horizontal. Thus the interaction between the two controls would be minimised. In recent times there has been quite a renewal of interest in the Theremin and there is a fair amount of information on the Internet. However, none of it is really helpful if you want to build your own Theremin. And this is where this completely new Theremin circuit comes into the picture. It has exactly the same operational characteristics as the original RCA Theremin but does not use valves (perish the thought). Instead it uses just three low cost ICs and a handful of other components. Not only that, our new Theremin is considerably smaller than the original design although you could build a large one if that’s what you fancy. We built ours into a medium sized plastic Jiffy box with the antenna and sensor loop mounted on opposite sides of the box. It includes a small Fig.1: the Theremin circuit involves three virtually identical oscillators, two to generate the tone and one to con­trol the volume. August 2000  17 Fig.2: the reference oscillator and pitch oscillator are mixed together in the product detector (IC1) to produce an audible tone which is amplified by IC2a and IC3. 18  Silicon Chip Fig.3: these digital scope waveforms show the reference and pitch oscillators locked together at 441kHz and the difference result is no output tone. Normally, the ref­ erence oscillator remains fixed while the pitch oscillator is varied by hand capacitance. loudspeaker for practice sessions and a line output for connection to a sound system. The only manual controls are an On/Off switch and volume control. The unit is powered by a 9V or 12V DC plugpack. Circuit principles The block diagram of Fig.1 shows the basic arrangement of the Theremin circuit. It comprises three oscillators which all operate at about 455kHz. The reference and pitch oscillators are mixed together to generate a beat signal which becomes the audi­ble tone while the volume oscillator is used to change the level of the tone output. The reference oscillator operates at a fixed frequency and is mixed with the pitch oscillator in the product detector (IC1). The pitch oscillator changes in frequency depending upon the amount of capacitance to earth presented by your hand when it is near the antenna. As noted above, the frequency will fall when the hand is brought near to the antenna and rises when it is further away. The product detector essentially multiplies the reference oscillator (f1) with the pitch oscillator (f2) to produce sum (f1 + f2) and difference (f2 - f1) frequencies. The sum (f1 + f2) signal is at around 900kHz which is easily filtered out with a low pass filter and we are left with the difference signal of f2 - f1 which comprises audio frequen­ cies from 1.4kHz down to below 10Hz. So if the pitch oscillator frequency is Fig.4: this is the line output signal when the pitch osc­ illator is 833Hz lower than the reference oscillator. Note the relatively clean sinewave output. 456kHz and the reference oscillator is at 455kHz, we will obtain a 1kHz audio output from the low pass filter. The audio output from the low pass filter is applied to a power amplifier which can drive a loudspeaker. The overall volume from the amplifier is set by the volume control VR1. The volume oscillator is controlled by the sensor loop which is also affected by hand capacitance. As you bring your hand closer to the loop, the frequency of the volume oscillator de­creases. This is fed to a bandpass filter which has a centre frequency (fc) which is higher than the volume oscillator fre­quency. So if the volume oscillator is operating at frequency f1 the level will be low. As the frequency increases, the level will increase as it approaches the centre frequency of the filter. This signal level is detected using a diode and filtered to produce a DC voltage. The following amplifier increases the DC voltage and the level shifter sets the voltage so that it can control the product detector output level over a suitable range via its transconductance input. Circuit details The circuit for the Theremin uses three JFETs (Junction Field Effect Transistors), four prewound IF (Intermediate Frequen­ cy) coils, three ICs, one detector diode, a 3-terminal regulator and associated resistors and capacitors. As you can see, all three oscillators are identical with the exception of the 100Ω drain resistor for Q3. Each oscillator comprises a junction FET (JFET) Q1 and a standard IF transformer, as used in low-cost AM radio receivers. The transformer comprises a tapped winding which has a parallel-connected capacitor to form a tuned circuit. The secondary winding couples the oscillator signal to the following circuitry. Each JFET drives a portion of the primary winding (ie, between the tap connection pin 2 and ground) while the signal across the full winding is applied back to the gate via a 68pF capacitor. This is the positive feedback which ensures oscilla­tion. To make them controllable by hand capacitance, the Pitch and Volume oscillators have the antenna and disc connected to the top of the tuned coil where they will have the most effect. The reference oscillator and pitch oscillator outputs are applied to an MC1496 balanced mixer, IC1. Resistors between the +6V supply and ground set the bias voltages for the inputs of the balanced mixer, while the 1kΩ resistor between pins 2 & 3 sets the gain of the circuit. IC1 provides a balanced output with signals at pin 6 and pin 12. These outputs are filtered with a 3.3kΩ pullup resistor and .047µF capacitor to produce rolloff above about 1kHz. This heavily attenuates frequencies at 455kHz. The output from pin 12 is AC-coupled to op amp IC2a which simply August 2000  19 Fig.5: the component overlay for the PC board. Note that IF trans­formers T1, T2 & T3 should all be fitted with white slugs, while T4 should have a black slug. buffers the signal before it is applied to volume control VR1. IC2a’s output signal also goes to the line output terminal. The signal from IC2a is AC-coupled to both VR1 and the line output to prevent DC voltage flowing through the pot and the line output. IC3 is an LM386 1W amplifier which The loudspeaker and on/off switch are mounted on the lid of the case and connected to the PC board using light-duty hookup wire. 20  Silicon Chip drives the loudspeaker via a 470µF electrolytic capacitor. The .047µF capacitor and series 10Ω resistor form a Zobel network to prevent spurious oscillation from the amplifier. Volume oscillator The output from the volume oscil- lator at the secondary winding of T3 is AC-coupled to the base of transistor Q4. This is connected as a common emitter amplifier with the collector load being a parallel-tuned circuit comprising an IF coil with inter­nal capacitor. T4 and the associated capacitor are tuned to a frequency just above the maximum available from the volume oscil­lator. The emitter resistor is bypassed with a 560pF capacitor which provides rolloff below about 400kHz. The output level from transformer T4 will vary in proportion to the frequency from the volume oscillator. This is because the filter provides a sharp rolloff below its tuning frequency and small changes in frequency which are below the centre frequency will cause large changes in the filter response. The action of this circuit is a simple frequency modulation (FM) detector. The high frequency signal from T4 is rectified by diode D1 and filtered to provide a DC signal which is amplified by op amp IC2b by up to 1000, depending on the setting of VR2. IC2b’s output is then fed to pin 5 of IC1 to vary the level of the audio signal. Oscilloscope waveforms The oscilloscope waveforms of Fig.3 & Fig.4 demonstrate the circuit operation. Fig.3 shows the reference and pitch oscilla­tors locked together at 441kHz and the result of that is no output tone. Normally, the reference oscillator remains fixed while the pitch oscillator is varied by hand capacitance. Fig.4 shows the line output signal when the pitch oscillator is 833Hz lower than the reference oscillator. Note the relatively clean sinewave output. The output level is a healthy 539mV RMS. Power for the circuit comes from a DC plugpack which is regulated by REG1, a 5V regulator. The output The PC board fits inside a standard plastic case, with the volume plate protrud­ ing through a slot at one end. Alternatively, the plate could be permanently fixed to the lid of the case or mounted so that it can swivel over the lid for easy storage. This view shows the mounting details for the telescopic antenna, which functions as the pitch control. August 2000  21 is “jacked up” by a nominal 0.7V by diode D2 to give a nominal +6V which will actually be around +5.7V. The input and output terminals of REG1 are decoupled with electrolytic capacitors to aid in supply filtering and to prevent instability in the regulator. Construction All the parts for the Theremin are assembled onto a PC board coded 01207001 and measuring 133 x 88mm. It is mounted in a plastic Jiffy box which measures 158 x 95 x 53mm. While our assembly description revolves around the plastic case with its small speaker, there is no reason why you couldn’t build it into a much larger case in keeping with a musical in­ strument. A larger amplifier and loudspeaker would also be a considerable benefit in the overall sound quality. You can begin construction by checking the PC board for any defects such as shorts between tracks, breaks in the copper tracks and incorrectly drilled holes. You will need slightly larger than the standard 1mm sized hole for the coil earth pins on the sides of the shielding cans, while holes for The Theremin will give more consistent results if it is mounted on a raised non-metallic stand so that it is at least 60mm from any surfaces. This stand was made from a discarded plastic panel and some plastic tubing. Table 2: Capacitor Codes       The completed Theremin, together with its plastic stand. You use your right hand to control the pitch by waving it near the antenna, while your left hand and the circular metal plate control the volume. Value IEC Code EIA Code 0.1µF   100n   104 .047µF   47n   473 560pF   560p   561 220pF   220p   221 68pF   68p   68 Table 1: Resistor Colour Codes  No.   1   1   6   2   1   2   1   1   8   1   1   1   2   1 22  Silicon Chip Value 1MΩ 270kΩ 100kΩ 10kΩ 6.8kΩ 3.3kΩ 2.2kΩ 1.2kΩ 1kΩ 820Ω 680Ω 150Ω 100Ω 10Ω 4-Band Code (1%) brown black green brown red violet yellow brown brown black yellow brown brown black orange brown blue grey red brown orange orange red brown red red red brown brown red red brown brown black red brown grey red brown brown blue grey brown brown brown green brown brown brown black brown brown brown black black brown 5-Band Code (1%) brown black black yellow brown red violet black orange brown brown black black orange brown brown black black red brown blue grey black brown brown orange orange black brown brown red red black brown brown brown red black brown brown brown black black brown brown grey red black black brown blue grey black black brown brown green black black brown brown black black black brown brown black black gold brown the PC stakes should be sized to suit their diameter; they should be a tight fit. Check that the PC board clips neatly into the plastic case’s integral side pillars. It may need to be filed down to make a snug fit. The component overlay and wiring details are shown in Fig.5. Insert the two links and then the resistors. Use Table 1 as a guide to selecting each value. Alternatively, use a digital multimeter to measure each resistor. The three ICs can be mounted next, taking care with their orientation. Make sure that IC2 & IC3 are placed in the correct positions. Next, the capacitors can be mount­ ed, noting that the elec­trolytic types are polarised and must be oriented with the cor­rect polarity, as shown. The MKT and ceramic types usually are coded and you can check this against the values shown in Table 2. The coils are prewound types each with an integral tuning capacitor and are mounted as shown. Be sure to place the ones with the white slugs (the threaded ferrite core) in the T1-T3 positions and the coil with the black slug in the T4 position. Now mount the JFETs (2N5484), transistor Q4 (BC548) and the 3-terminal regulator. Diodes D1-D3 can be mounted next, taking care with their orientation. Finally, mount potentiometer VR1 and trimpot VR2. VR1 is mount­ed using five PC stakes as shown. Three PC stakes connect the pot terminals to the PC board while the remaining two PC stakes are soldered to the pot body to hold it in place. Scrape the passiv­ated coating off the pot body adjacent to the PC stakes for easy soldering. With the PC board complete, you are ready to work on the case. You will need to drill holes in the sides of the box for the DC panel socket, the RCA socket and for the antenna securing screw. Volume plate The volume plate is made from light gauge aluminium 70mm in diameter and is connected via a lead and solder lug to the PC board. We mounted the volume plate on the prototype so that it could slide into the case when not in use. This requires a narrow slot to be cut into the side of the case. We made the slot by drilling Parts List 1 PC board, code 01207001, 133 x 88mm 1 plastic Jiffy box, 158 x 95 x 53mm 1 front panel label, 155 x 92mm 1 9VDC or 12VDC 300mA plugpack 1 telescopic antenna (pitch antenna) 1 70mm diameter (or 70mm square) 1mm aluminium plate (volume) 1 DC socket (2.5mm diameter pin) 1 panel-mount RCA socket 1 50mm 8Ω loudspeaker 3 2nd IF coils (DSE L0260 white) (T1-T3) 1 3rd IF coil (DSE L0260 black) (T4) 1 SPST rocker switch (S1) 1 knob 2 crimp eyelets 1 M3 x 15mm screw 1 M3 x 10mm screw 3 M3 nuts 1 200mm length of yellow medium-duty hookup wire 1 200mm length of blue medium-duty hookup wire 1 50mm length of 0.8mm tinned copper wire 1 short cable tie 13 PC stakes 1 10kΩ log pot (VR1) 1 2kΩ horizontal trimpot (VR2) a series of small holes and then filing it to the cor­rect size. If you don’t want to go to the trouble of making the slot you can permanently attach the volume plate to the lid of the case or mount it so that it can swivel over the lid for easy storage. Attach the front panel label to the lid and drill the holes for the switch and some holes for the loudspeaker. We mounted the speaker by smear­ing super glue around its perimeter and then placing it inside the lid. Follow the wiring details of Fig.5. You can use hookup wire to connect the sockets, switch S1 and the loudspeaker to the PC board. The antenna is attached with an M3 x 15 screw plus an M3 nut which is secured to the case with another M3 nut. The eyelet lug is held beneath the Semiconductors 1 MC1496 balanced modulator (IC1) 1 LM358 dual op amp (IC2) 1 LM386N-1 1W amplifier (IC3) 1 7805 3-terminal regulator (REG1) 3 2N5484 N-channel JFETs (Q1-Q3) 1 BC548 NPN transistor (Q4) 1 1N914, 1N4148 signal diode (D1) 2 1N4004 1A diodes (D2,D3) Capacitors 2 470µF 16VW PC electrolytic 1 100µF 16VW PC electrolytic 6 10µF 25VW PC electrolytic 1 2.2µF 16VW PC electrolytic 8 0.1µF MKT polyester 3 .047µF MKT polyester 1 560pF ceramic 3 220pF ceramic 3 68pF ceramic Resistors (0.25W, 1%) 1 1MΩ 1 1.2kΩ 1 270kΩ 8 1kΩ 6 100kΩ 1 820Ω 2 10kΩ 1 680Ω 1 6.8kΩ 1 150Ω 2 3.3kΩ 2 100Ω 1 2.2kΩ 1 10Ω Miscellaneous Solder, super glue. nut and the wire connects to the PC board as shown. A connection is made to the volume plate via an eyelet lug using an M3 x 10mm screw through a hole which is held using a nut. Setting up When your Theremin is complete, check your work carefully. Apply power and check that there is a nominal +6V between the case of one of the transformer coils T1-T4 and pin 8 of IC2 & pin 6 of IC3. The voltage should be between +5.6V and +5.8V. Adjust VR2 so that pin 1 of IC2 goes to about +4.3V and wind VR1 slightly clockwise from its fully anticlockwise posi­tion. Use a plastic alignment tool to rotate the slug in trans­former T2 slightly until a tone is heard in the loudspeaker. August 2000  23 Fig.6 actual size artwork for the front panel. Fig.7: actual size artwork for the PC board. Then adjust it to obtain a good frequency range when your hand is brought near to the extended antenna. The note should be at its highest when your hand is away from the antenna and should fall to a very low frequency (just a growl) when your hand is very close to the antenna. If the effect is the reverse of this (higher frequency as your hand is brought close to the antenna) then adjust the slug in the opposite direction until the effect is correct. Note that you must do this adjustment away from the effects of metallic objects or the Theremin will require retuning when removed from these grounding sources. In fact, the Theremin will give more consistent results if it is mounted on a raised stand which keeps the unit at least 60mm from any surfaces. The stand should be made from a non-metallic material. Volume plate alignment The volume operation is set by adjusting the slug in T4 until the voltage at the cathode of diode D1 is at +1.7V. Then carefully adjust VR2 so that the volume is at its maximum when your hand is away from the volume plate. 24  Silicon Chip Bringing your hand close to the plate should reduce the volume. You may need to set VR2 so that the volume just goes to its minimum level when rotated anticlockwise. You then slowly adjust it clockwise until the volume just snaps into full level. If the volume does not reduce with your hand approaching the plate and the level remains essentially constant or if the level rises, then T4 is adjusted with the slug too far clockwise. This means that the circuit is op- erating with the volume oscillator equal to or higher than the tuned frequency. Adjust the slug of T4 anticlock­ wise so that the volume plate operates correctly. Note that when the lid is fitted to the case, the tuning will change. We drilled a hole in the lid to allow VR2 to be adjusted with the lid in place. Also, the adjustment of VR2 will set the sensitivity of the Theremin volume plate to hand move­ment. The more precisely VR2 is adjusted, the SC greater will be the sensitivity. MAILBAG Manual wanted for Osborne monitor I am attempting to repair a 20inch Osborne high quality monitor, type MON 020. It was given to me as it was not cost effective to have it repaired commercially. It has burn­ ed induc­tors in the horizontal output stage and the horizontal output transistor and one other transistor on the heatsink have been removed by a previous repairer. I realize that Osborne as a brand no longer exists but I feel that the monitor has some useful life left in it and would like to attempt a repair. Is there anyone who can help me with device numbers for transistors 7605 and 7615. (These are the numbers on the PC board.) The inductors I can rewind myself. I would be happy to pay a reasonable amount for a manual or circuit diagram. A circuit would be most helpful but not essen­tial. Ian Thomson, 80 Bungarribee Rd, Blacktown NSW 2148, Phone (02) 9621 2938 thomsi<at>start.com.au or thomsi&Integral.com.au Modern cars are only evolutionary In the July 2000 “Publisher’s Letter” Mr Simpson talks about 42V car electrics. In the opening sentence he states, “Most people would agree that there have been radical changes in the design of automobiles in the last 15 years or so.” I must dis­agree with this opinion, as quite frankly, at best, the adapta­tion of electronic fuel injection, computer controlled transmis­sions and the like are at best a refinement of a very old tech­ nology. Improvement, yes, radical change, I don’t think so. It is too easy to get caught up in our own brilliance and forget that automobiles, as far as their general principal of operation goes, have not changed in over 100 years. We are still driving cars that employ a largely inefficient internal combus­ tion engine, driving through some sort of transmission to either the front, back or all four wheels. This description equally applies to the first Model T Ford, or the latest Commodore. The biggest real difference between them is the styling. We should not confuse evolution with revolution. The advent of safety features such as ABS brakes and air bags are welcome additions to the modern car; as is anything that can improve our chances of surviving a crash. These are evolutionary devices and do not change the way the car operates. Many creature comforts rely on electronics such as central locking, climate control air-con, CD players, satellite navigation, DVD etc. Again, let’s not pat ourselves on the back too quickly. Most of these exist out­side of the motor car already. Fitting them into a vehicle hardly makes them a giant leap for mankind. They do not contribute to what the car’s main purpose is, and that is to propel the vehicle in the desired direction. They just make it more pleasant or safe while we’re driving. You might think that I am against all this gadgetry. Not so. It’s just I wish we could make some real advances in the automobile, such as a genuine radical change to the method of propulsion, with large improvements in efficiency. The only changes between models that are obvious now are the restyling changes, which are nothing more than a new grille here and a new curve there. Right now cars are starting to get sharper, squarer shapes around the boot area and straighter glass lines. Didn’t we see this in the eighties? Unfortunately even at the young age of 32 I probably won’t live to see the death of the internal combustion engine, although I hope I’m wrong. Personally I can’t wait for the flying cars out of the movie ‘Back to the Future 2’. Now that would be a radical change. However, I don’t think the oil companies want us to have that just yet! Paul Campbell, Arana Hills, Qld. Who is in charge of the kingdom? I would like to add my experience with Queensland’s Elec­ trical Workers Board. Firstly, your previous correspondent was in no way being too harsh on this group whose primary interest is in self-perpetuation. My field of work is broadcast electronics where I have maintained high-power radio and television transmit­ters for over 20 years. Here we regularly work with single and 3-phase mains oper­ated equipment where input powers in the 100s of kVA feeding DC supplies of 25kV at many amps are not uncommon. I am a trained professional and perform maintenance on this equipment with skill and care, where adherence to safety procedures are paramount and yet I fall into the same category; I am not permitted to install a new GPO in my own home or build a kit that delivers switched 240VAC. To be honest I had given up trying to do anything about this. I’ve come to expect that lugs bolted to contactors glow cherry red when tightening the bolt is forgotten or that if you order a 10A 3-phase supply, it may be wired with single phase 3-core 2.5mm building wire where two reds and a black are Actives, the other black is Neutral and use either 1 or 2 greens as Earth. When I asked about sleeving, they continued on page 91 August 2000  25 CircuitMaker 2000 The Virtual Electronics Lab If you thought that access to the latest printed circuit board design and circuit simulation tools was restricted to big companies with big budgets, think again! This review looks at CircuitMaker 2000, a complete design solution aimed at small to mediumsized projects and users. By PETER SMITH CircuitMaker 2000 is a new release of a mature product developed by the US company MicroCode Engineering. Micro­ Code have a 10-year history in the development of affordable electronic design automation (EDA) software. MicroCode Engineering were recently acquired by Protel International, a name that most of us are familiar with (we reviewed Protel 99 in the January 2000 issue). The upshot is that CircuitMaker is now being sold and supported in Australia. 26  Silicon Chip The CircuitMaker 2000 package includes schematic capture, analog and digital circuit simulation and PCB layout software and is offered in both “Standard” and “Professional” editions. We reviewed the Professional edition but we’ll note the differences as we look at each of the major functions. Let’s jump right in … Schematic capture The first stage in bringing a design to reality is getting the schematic down on “paper”. CircuitMaker 2000’s schematic editing environment is based around the familiar Windows-style interface, and is one of the easiest-to-use I have seen. A comprehensive library of component symbols is directly accessible from a browser panel on the left side of the workspace (see Fig.1). A handy feature allows assignment of shortcut keys to the most common components in a circuit, which means that once you’ve found the symbol you want the first time, you don’t have to waste time searching for it again. If you need a symbol that’s not in the library (and that shouldn’t be too often), you can use the inbuilt Symbol Editor to edit an existing symbol or create a new one from scratch (see Fig.2). Unlike the schematic-editing environment, I think that a newcomer would find the Symbol Editor quite awkward and decidedly non-intuitive. There is no access to on-line help while the Symbol Editor is open, either. Ho-hum, it really does provide everything needed to edit or create both simple and complex symbols, with the ability to link all kinds of simulation data (see “Circuit simulation” below). If you’d like to see the complete list of devices included with CircuitMaker 2000, you can download the Device Library Guide (in Adobe PDF format) from http://www.circuitmaker.com/ downloads/libraries.htm Wiring it all together is a piece of cake. Click on a device pin or a wire, drag the cursor to the target connection point and release, and Circuit­Maker automatically routes the wire. And you don’t have to precisely place the wire start and end points, as CircuitMaker automatically captures the cursor when it is moved close to any node (like a device pin). As you’d expect, wires can be routed manually if desired. A large cursor Fig.1: finding the right symbol and wiring it up is a simple task in the Schematic Editor. Fig.2: if you need to create a new symbol (or change an old one), you do it in the Symbol Editor. Put on a pot of coffee if it’s your first attempt, though . . . makes it easy to line everything up neatly – very useful in this package as the “snap to grid” option snaps symbols to a grid but not wires. Editing your masterpiece is very straightforward. Symbols can be mov­ed around the workspace with connecting wires intact, as they are automatically “rubberbanded”. Wires can be lengthened, shortened or deleted with little more that a right mouse click, or moved intact to a new position by clicking and dragging. Precise alignment of objects can be achieved by “nudging” them into position with the arrow keys. Circuit simulation With the schematic completed, you can move directly to PCB layout and physical prototype. But what if you could test (optimise, demonstrate) your design first? CircuitMaker 2000 includes a powerful analog and digital circuit simulator that is tightly integrated with the schematic editor. Most symbols in the library are linked to pre-defined simuAugust 2000  27 Fig.3: digital simulation is easy to drive and the results are plain to see. Here we follow the condition of five points in the circuit (TP1 to TP6) with the logic analyser. Simple breakpoints and single or multiple-cycle stepping lets you slow things down to human level. lation information (called “models”), so once your circuit is complete, you can begin simulation with very little setup. Over 4000 device models are included in the Standard edition, and 6000 in the Profession edition. Two independent simulation modes are provided. For analog or mixed analog and digital circuits, Circuit­Maker 2000 includes an enhanced SPICE 3f5 and XSPICE compatible simulator. SPICE (a classical computer acronym meaning “Simulation Program with Integrated Circuit Emphasis”) is the industry-standard method for circuit simulation. The second mode supports digital simulation only and is of proprietary design. Why? Well, the CircuitMaker people have been able to incorporate some very nice interactive features in this mode, making it a powerful instructional tool. Lets look at this mode first. Digital simulation Any complete digital circuit includes some kind of clock source, so the first step is to connect either the logic pulser or logic sequencer from CircuitMaker’s “instrument” devices. Next, test points can be connected to each node that we would like to examine (instruments and test points are placed from the component browser and connected just like regular components). Finally, clicking on the “run” button launches a “real-time” simulation of the circuit, with waveforms for each test point displayable either in split-screen or full-screen mode (see Fig.3). Fig.4: you can have your tudents pulling their hair out with the digital simulator’s Device Faults function. 28  Silicon Chip Digital simulation includes a number of major features that make it ideal for educational purposes. Firstly, a built-in logic probe enables instant display of the logic state (low, high or high-impedance) of any point in the circuit, much like using a real probe on a real prototype. Secondly, a trace mode can display the logic state of every wire in the circuit by changing its colour to either blue, red or green to indicate a low, high or high-impedance state respectively. Another useful feature allows faults to be introduced into the circuit for a real “hands-on” learning experience (see Fig.4). And lastly, CircuitMaker 2000 includes a handful of “animated” components. Devices like 7-segment displays, buzzers and LEDs function just like their real-world counterparts. And there’s even a launchable rocket! (see Fig.5). Analog simulation A whole host of analyses can be performed on both analog and mixed analog and digital circuits using the SPICE simulator (see Fig.6). These include DC Analysis, AC Analysis, DC Operating Point, Transient Analysis, Parameter Sweep and Fourier Analysis. The Professional edition adds Transfer Function, Noise, Temperature Sweep, Monte Carlo and Impedance Plot analyses. A variety of virtual instruments are available for generating stimuli and viewing the simulation results. These include an Oscilloscope, Digital Multimeter, Bode Plotter, Curve Tracer, Signal Generator, Data Sequencer, Logic Analyser, Logic Probe and Logic Pulser. For my money, the stand-out part of the CircuitMaker 2000 package lies right here in its analog simulation capabilities. Even a beginner to simulation can quickly get meaningful test results. A probe tool allows instant measurement of voltage, current and power almost anywhere in the circuit. Just point and click and the results are immediately displayed on the selected instrument for analysis. Conversely, some other packages insist that you define test points and connect instruments before the simulation even begins. Sensible default simulation parameters, automatic waveform scaling and zooming and many other handy little shortcuts go together to make this simulator a very useful tool indeed. PC board layout “TraxMaker” is the name of the PCB layout software included with Circuit­ Maker 2000. Although it’s a separate module, it is closely integrated with the schematic editing software. To transfer information from the schematic editor to TraxMaker it’s just a matter of clicking on the “Export PCB Netlist” button. To make life even easier, you can have TraxMaker position all components on your board ready for placement and routing (see Fig.8). A handy addition to the Professional edition also allows direct import of Protel Advanced PCB2 and Advanced PCB3 ASCII files. Manual track placement and editing are a breeze and have a familiar feel. For example, a right mouse click provides easy access to the most commonly used functions, as do shortcut keys and menu bar buttons – just like the schematic editor! Individual tracks, groups of tracks or the entire board can be routed automatically if desired. The Professional edition includes a more sophisticated autorouter (call a “ripup and retry” maze autorouter) which has a higher completion rate and more efficient routing (meaning less vias). All routing is grid-based, with a maximum resolution of .025mm (.001 inch). Up to eight copper layers are supported (six signal layers and two power planes) as well as solder and paste masks, keep out layer and reference layer – more than enough for most small to medium-sized projects. TraxMaker includes a comprehensive component footprint library. And if you can’t find what you want in the library (see Fig.10), editing or expanding it is a cinch. New footprints are drawn directly in the PCB editor space using standard primitives like pads, tracks and text, then grouped and included in the library in a single step. Great! Fig.5: interactive devices make your digital simulations come to life! This example shows switches, a piezo buzzer and a LED display that really work. Fig.6: CircuitMaker’s analog simulation is first rate. Here we examine the voltage at four nodes in an astable multivibrator circuit. Checking your work Before shipping your design off to be made, you can be sure that it’s right (at least electrically!) by running the Design Rules Checker (see Fig.11). It looks for basic problems in your layout like open circuit nets and clearance violations (tracks/pads short circuited or too close together) and generates a detailed report. In common with all PCB layout software, TraxMaker generates industry-standard output file formats (Gerber and Excellon) that will be acceptable to all PCB manufacturers. CircuitMaker 2000 Professional edition includes an additional piece of software called TraxCAM PRO, a fully featured Gerber viewer and ediAugust 2000  29 Fig.7a (left & Fig.7b (above): setting up two of CircuitMaker’s instruments. Fig.8: two mouse clicks gets your design into the PCB layout software. tor. TraxCAM PRO allows you to query, edit, print and add copper pours to your design prior to manufacture. Last word Overall, we were impressed with the simplicity of use and value for money in this package. Its circuit simulation capabilities alone would make it an attractive proposition for institutions involved in electronics training. Like more information? Fig.9: editing a single-sided design in TraxMaker, the PCB layout module. In fact, this is the PCB from the 40V 1A power supply project described in the August 2000 issue. The design was imported from a Protel Advanced PCB file (ASCII format). Fig.10: TraxMaker’s footprint library is comprehensive and easy to use. 30  Silicon Chip Loads of information and a downloadable demo is available from the CircuitMaker web site at http://www. circuitmaker.com Local telephone support is available on 1800 676 684 or e-mail aust-support<at>circuitmaker.com The pricing details are as follows: (1) Standard Edition $645 (includes GST); (2) Professional Edition $1195 (includes GST). For sales enquires phone 1800 030 949 or e-mail austSC sales<at>circuitmaker.com Fig.11: a Design Rules Checker allows final checks on your work before sending it to manufacturing. August 2000  31 ! Come in r !! e r e n n i SSpppi n S S SS ppi r SSppiinnnnneee SSppiinin eerrr SSSp ! S SS pi SSppiinnnne r!! e ! r r ! ! No, it’s not our version of the great Aussie game. This “Spinner” is one of the simplest projects we’ve ever published – yet also one of the most intriguing. It writes messages in thin air as you spin it! It’s very easy to build, costs very little and makes a great “first project”. W ith just 13 components and a couple of switches to solder in place, this project is about as simple as projects can get. Yet it will amaze you and all who see it in operation. Messages seem to write in mid-air when you give it a spin! There is no motor to spin the Spinner – it is operated by finger power. All you do is set the message you want to display by appropriate switch pushes, then flick the message stick on its axis so that it spins. There are two parts to the Spinner: the message stick itself, which contains all the components, and a handheld battery pack which also provides the axle on which the stick can spin. The axle is a little unusual – it is in fact a 3.5mm phono plug mounted in the end of the battery pack. On the stick is the matching 3.5mm phono socket. When you “plug” the battery pack onto the message stick’s socket, as well as creating the spinning mechanism you’re also supplying power to the system. Clever, eh? But wait, there’s more! Attached to the back of the PC board, close to the axle, is a short 32  Silicon Chip length of fairly thick tinned copper wire, almost (but not quite) long enough to touch the surface of the end of the battery holder as the board is spun around. Secured across the end of the battery holder is another length of tinned copper wire, just high enough to be hit by the wire sticking out from the PC board. So as the PC board is spun around, once every revolution these two wires touch. This tells the circuit to dump the contents of the on-board memory (actually a small PIC microcontroller chip) which in turn tells the LEDs to light up in certain patterns. If the board is spun slowly, all you will see is a line of glowing LEDs for a short time and then nothing. But if it is spun at a reasonable speed and in the right direction (by giving it a good flick with your finger) the LEDs are moving as the micro­ controller instructs them to turn on and off. Like the moving message display Design by Attilla Aknar* Words by Ross Tester board we featured last issue, the LEDs spell out a message. In fact, there is not really a message at all but the eyes, with their persistence of vision, “remember” how the LEDs glow over the course of their travel and that’s how the message is produced. And all this appears to happen “in space” – the spinning PC board moves too fast to be focused on (it actually appears as a blur) but the eyes (and the brain) remember the message as if it was really there. The length of the message (not the number of letters but the actual width of the letters around the arc) depends on the speed of the spinning PC board. If you spin it really quickly the message can occupy a significant proportion of the circle. As it slows down (which of course it must do due to friction) the letters become thinner and thinner. Eventually (as the spinning stops), the whole message is displayed in the width of one LED – or 5mm. This is of course completely unreadable. The messages There are three different spinners available, depending on which PIC Look mum, it’s magic! This photo is not retouched – the image that you see is part of the image that we saw written “in space” (it happens to be the designer’s name but it has been abbreviated a bit by the length of time the camera shutter was open – about 1/8 second). With a good swift flick, the message can occupy a good 180° of arc. chip is supplied (each contains different programming. First is the Spell Spinner which displays each letter of the alphabet and a word beginning with that letter (eg, A APPLE, B BOY, C CAT and so on). Pressing the up and down pushbutton switches advances the message one letter. The third switch is not used in this, or the next Spinner. Second is the Message Spinner which has ten different messages programmed (some examples are shown below). Stepping between the messages is also done with the up/ down push buttons. Finally there’s the Programmable Spinner where you enter your own message with the up and down pushbutton switches. As you enter each letter of your message, you place it in memory by pushing the third switch. It will take you a while, because each press of the switch advances one letter of the alphabet. So if you want to program in a message saying “MY NAME IS XERXES” you’re up for about 200 button presses! (Lucky you if your name is ABE – only about 110 button presses!!!) Construction As the chances are that this could be your first project, we’re going to cover this section in much more detail than normal. First, examine the PC board closely (you might need a magnifying glass for this). Check to see if there are any broken tracks or if any points are bridged together. We’ve published the full-size PC board pattern to help you do this, Some of the messages displayed in version two of the Spinner. Another six or so are accessed by pressing the up/ down pushbutton switches. August 2000  33 There’s not much to it, is there? A PIC microcontroller, five LEDs and a few other components make up The Spinner. The messages depend on which PIC you use. though with a board like this (which has very fine tracks and close track spacing) making a board yourself (at home, school, etc) is pretty much out of the question. Besides, the PC boards have been priced very well to make it a cheap kit to buy. Having satisfied yourself that the PC board is as it should be, it’s time to start inserting and soldering components. Start with the five 100Ω resistors. These 1/10W resistors are much smaller than the 1/4W resistors we normally use in projects so require a little more care than normal. All of the resistor leads should be bent up 90° so that each resistor forms a “U” shape with the verticals exactly 7mm apart and parallel, with the resistor body itself across the bottom of the “U”. The components all mount on the side of the PC board opposite to the copper tracks. They do not need any glue or other method of holding in place because their legs or leads poke through the board and are soldered to the copper pads. (If you’re not new to this, don’t laugh – we all had to start somewhere. And we’ve seen some beautifully constructed PC boards with the components all carefully glued in position on the copper side of the board with not a milligram of solder to be seen!!!) Place the resistors in their appropriate holes one by one, soldering them as you go. Because of the extremely fine tracks and tiny pads on this board it’s easy to damage it with too much heat from your soldering iron. Ideally, you need a fine to very fine tipped iron (with the tip itself clean and well tinned), preferably temperature controlled. If you haven’t soldered before, practise with some other components or hook-up wire before soldering the board. When you’re ready, apply only as much heat from the iron as necessary to make the solder flow evenly around the resistor lead, securing it to the pad underneath. By the way, make sure the solder you use is intended for electronics applications. The solder you buy at your local hardware store is probably not suitable – it often contains flux which is corrosive. Having successfully soldered the resistors, now try the five LEDs. These are polarised devices – if they are inserted back to front they won’t work! Notice how the LEDs have one flat side on them? This marks the cathode (or negative side), usually identified with the letter “K”. The flat sides of the LEDs ALL go towards the centre of the PC board. Also, there are extra pairs of holes on the board for different components which we don’t use here. Make sure you get the two leads from each LED into the right holes and the right way around! Incidentally, you may be wondering why we use a “K” for cathode and not a “C”? Two reasons: transistors, as you may know, have three leads – the emitter, base and collector (or E,B and C). Using “C” for a cathode might confuse it with a “C” for collector! Secondly, the German word for cathode is kathode – so we use a K instead of a C. This applies to all diodes, not just LEDs (which is short for Light Emitting Diode). We’re going to leave the integrated circuit (or IC) until last but there is Use the photograph, component overlay and PC board pattern to help you build any version of The Spinner. The PC board pattern above is as seen looking at the back of the board while the component overlay above that again is as seen if you had X-ray vision and could see the copper tracks through the board from the component side. 34  Silicon Chip Side-on view of the acrylic battery holder which doubles as a handle. The 3.5mm plug emerging from the right end supplies power and is also the axis on which the PC board turns. This, and the trigger wire, can be clearly seen in the end-on shot at right. no reason why you cannot solder in its 8-pin socket now. Note that the IC has a notch in one end and so does the socket. This allows you to work out which is pin 1. With the IC (or socket) held upright with the notch at the top, pin 1 is always the top pin on the left side. The pins then number down the left side (in this case 1,2,3,4) and then up the right side, 5,6,7,8 from the bottom as you are holding it. OK, put the IC aside for a while and very carefully solder in the socket so that its notch is towards the centre of the board. Again, be very careful – some of the very fine copper tracks go between the IC socket pads. While they are covered with a green solder mask (which protects the tracks and helps keep solder away) it is possible to solder across the tracks. We’ll ignore the trigger pick-up and 3.5mm socket for a moment and solder in the small (0.1µF) ceramic capacitor next to the IC socket and the 100µF Another view of the trigger wire and its pickup, this time in a close-up photo of the assembled Spinner. electrolytic capacitor on the other side of where the socket will mount. You will note from the photographs that this capacitor is lying on its side. It’s not vital that this is done but laying it over like this reduces the overall height of the PC board, making it less likely to snag or catch anything else while spinning. What is important is the polarity: electrolytic capacitors must be connected the right way around, otherwise they can actually explode, spreading gunk far and wide (and it’s not good stuff to get in your eyes!). This may not happen immediately but it will happen. Electrolytic capacitors normally have a stripe down one side in which there are “–” (minus) symbols. The lead closest to this is the negative lead. The other lead is obviously the positive lead (+) and on some PC boards you might find only a + symbol. This PC board fortunately has both + and – identified so it’s even harder to make a mistake. The final component to solder in is the 3.5mm socket. This mounts through the PC board from the component side with a nut securing it in place on the copper side. However, that’s not all that’s required: you also need to connect two of the three terminals on the socket to the PC board. The easiest way to do this is use some short lengths of wire which you’ve cut off resistor or capacitor leads (often called pigtails). These simply solder between the socket terminals and the PC board below. Note though which way around the socket goes. It has two terminals on one side and one on the other – the two terminal side faces towards the IC socket. The terminal closest to the PC board (on the two terminal side of the socket) and the single terminal on the other side are the ones to connect to the Parts List – Spinner Message Stick 1 PC board, 285 x 14mm, coded SpinStick V1.0 1 3.5mm mono phono socket, chassis mounting 1 3.5mm mono phono line plug (no cover) 1 8-pin DIL IC socket 3 mini pushbutton SPST momentary contact switches, PC mounting (2 only required for spell or message versions)* Semiconductors 1 12C509A PIC micro, programmed in one of three ways* 5 ultrabright red LEDs, 5mm Capacitors 1 100µF 16VW PC mounting electrolytic 1 0.1µF ceramic Resistors (1/10W, 5%) 5 100Ω (brown-black-brown-gold) Miscellaneous 1 clear acrylic tube, 133mm long, 38mm OD with end-caps 1 8mm length stiff solderable wire for trigger (eg, bronze)* 1 30mm length stiff tinned copper wire* 1 4xAA battery holder (flat style) 4 AA batteries *SEE TEXT August 2000  35 board. You don’t need to solder the third terminal because this is actually a switched terminal, disconnected when a 3.5mm plug is inserted. We said that the socket was the final component, which is strictly true. But we still need to solder in the trigger “pickup”, a short length of heavier-gauge tinned copper wire. Using resistor or capacitor pigtails here would be futile because they would bend too easily and so not make reliable contact. You need to have about 7mm of wire protruding from the copper side of the board. We used a length of wire a bit over 10mm with the remainder protruding from the top (component) side of the board. This can be used as a test point later on to check triggering. The wire we used was a tight fit in the PC board hole – again, this adds strength to the pickup. You will note from the component overlay that the mounting point is closest to pin 1 of the IC. Once soldered in, we bent the wire towards pin 8 at about a 45° angle. This can be adjusted later to ensure a contact is made. Finally, carefully insert the IC into its socket, making sure the notched end in the IC matches the notched end of the socket and that all eight pins correctly mate with their socket contacts. The “handle” The other section of the Spinner is the acrylic handle, which contains the batteries (4 x AA in a battery holder) and houses the 3.5mm plug on which the PC board spins. This plug mounts through one of the end caps in the exact centre. Alongside is a loop of tinned hookup wire which lies flat across the end cap and is connected to the negative battery lead. This is of course what the trigger contact “wipes” over each rotation, triggering the message. Start assembly of this section by finding the exact centre of the end-cap with all of the holes in it (the other end cap is plain). Drill a 5mm hole in this end cap. The 3.5mm plug, without its plastic cover, screws into this cap from the outside. There is a thread on the 3.5mm plug which will tap into the plastic of the 36  Silicon Chip the two ends together and solder them to the negative battery lead/3.5mm plug body terminal. Push the other end-cap onto the acrylic tube, slide the battery connector (with four AA cells) in the other end (it’s a tight fit) and finally push the end-cap and 3.5mm plug assembly onto the tube. That completes the assembly – all that remains is setting the trigger wire and checking that it works. Finishing off end-cap making it a snug fit but for security, once all soldering is done, a dob of glue (contact adhesive or similar) over the back of the plug will help hold it in place. Solder the red lead from the battery holder to the centre pin terminal of the 3.5mm plug and the black lead to the body terminal. Next, pass a length of tinned copper wire through one of the holes in the end-cap, wrap it over the edge, across the front back and through the same hole. Fashion this right into the edges of the cap with fine-nose pliers. Solder Push the Spinner PC board 3.5mm socket all the way onto the 3.5mm plug on the handle. Angle the trigger wire until it just clears the surface of the end cap but hits the tinned copper wire each time it passes over it. There is enough spring in the trigger wire to ride over the tinned copper wire and return to the same place. (Obviously, you can only turn the Spinner one way because turning it backward – ie, anticlockwise – will cause the trigger wire to snag). As you make the adjustment, you should find the LEDs flash each time the trigger wire contacts the wire on the end cap. If it does, your Spinner should be working properly. Now hold the handle firmly with the Spinner facing you and give the PC board a good flick in the clockwise direction (you’ll get the best spin by flicking as close as you can to the handle. You should be able to read the message displayed even though you can’t see the PC board. Depending on the version you’ve built, pressing the programming switches (as detailed above) will change the displayed message up or down or let you enter your own. Now you’re ready to amaze your SC family and friends! Where do you get it? The Spinner was designed by 4D Systems Pty Ltd, who hold copyright on the PC board, the design and on the program residing in the PIC. A complete kit of parts is available from 4D Systems for $24.95 (including GST) plus pack and post. Don’t forget to specify which type of Spinner you want. Contact 4D Systems at Suite 2, 3-5 Station Road, Auburn NSW 2144. Phone (02) 9649 5065; fax (02) 9649 4324 Email: sales<at>4dsystems.com.au Web Site: www.4dsystems.com.au * Atilla Aknar is Managing Director of 4D Systems Pty Ltd. Clock Cam THUMPER Available in two models ! 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Compact 23CM AC/DC NETWORKING ? * 5 port HUB 10Mbs - $69.00 * PCI Network Card RJ45/BNC - $25.00 * ISA Network Card RJ45/BNC - $25.00 * 5mtr CAT5 Cable - $8.95 Also available - Fibre - 100mbs HUBS Media Converters - Transceivers etc. Corperate Price Program Available Contact Jeff now for details. TV/VCR Combo Line recording, AV In/Out, Remote Control. 12 volt /240 volt operation 288W x 315H x 232D Only $699 division of Yager Electronics Pty. Ltd. - ABN: 19 060 819 516 plus $20 delivery E.A.O.E. Shop 501 Capital Centre 255 Pitt Street, SYDNEY NSW 2000 PO BOX Q43, SYDNEY NSW 1230 Ph: 02 9264 0717 Fax: 02 9264 0817 email: yager<at>mpx.com.au www.optionalpower.com.au Mailorders - Cheques, Visa, Mastercard, Bankcard, Amex, Diners accepted. C.O.D. arranged. August 2000  37 SERVICEMAN'S LOG It doesn’t pay to be too smug It sure doesn’t pay to be too smug, not even in one’s own mind. As sure as a job looks like a snack, it’ll turn out to be sour, particularly when older sets are involved. That’s just what happened with one job this month and then there was a bril­liant restoration job that bounced! Despite my never ending bad experiences with sets over 10 years old, I never seem to learn my lesson. Is it because one is reluctant not to use the knowledge learned over the decade or is it because I play down the inherent problems of equipment that’s generally past its use by date? Which ever it is, I find it hard to go past a Philips KT3-A3 (CH285) as I know it so well and it is a “technician-friendly” chassis. However, I find it hard to admit that, 15 years later, the sort of faults I am now encountering are often new, as all the most likely 38  Silicon Chip faults have already been fixed – it is only now that other unusual parts are breaking down. I was in just this frame of mind when I was faced with a challenge from young Tim, a field technician for a large opposi­tion service organisation. He had encountered a set – covered by one of their service contracts – which lived not far from the ocean. The fault was no sound or picture and the set was pulsat­ing. They hadn’t been able to solve the problem and he asked if I would “take a look at it”. Not wishing to show I was over the hill to a young upstart, I foolishly accepted the challenge. Fortunately Tim had agreed to deliver the set to my work­shop and leave it with me – not that I minded, as I was full of confidence in what I considered to be an old faithful and was sure it would be all over in about 15 minutes. Actually, I was so confident I really wanted him to hang around so that I could show off but he had other calls to attend to and was away before I had the back off. The thing that was most obvious immediately was that it was very corroded and, in the EHT section, the tripler and the hori­zontal output transformer had both been replaced and silicone had been generously applied everywhere. Despite this, the first thing I did was unsolder the tripler and switch on. Immediately, the sound came on and I could hear the horizontal timebase whistle. The main HT was spot on at 129V. Bullseye! Goodness me, what a genius I am; what a piece of cake! These and other conceited thoughts raced through my mind as I fitted a new tripler. I was reaching for words like “legend” by the time I switched the set back on only to find that the fault was exactly the same. Oops! – one instantly deflated ego. Well, it’s not absolutely unknown for brand new triplers to be crook (so I told myself), so I fitted yet another. The set continued to pulsate with the tripler in circuit and operate “correctly” without it. How could this be? Was it an excessive load problem or a lack of supply current? I disconnected the EHT to the final anode of the tube and unplugged the CRT socket to eliminate a faulty picture tube. I also checked the 300V unregulated power source. Both were OK. I felt it was unlikely to be the new horizontal output transformer – unless the wrong type had been fitted – but even that was unlikely; after all, it had been working. Next, I unsoldered the focus lead from the tripler, then disconnected the remaining A (capacitor) and D (diode) leads to the tripler. It was only when the D lead was disconnected that the set started to work – in fact, I even had a colour picture! It wasn’t too crash hot, with lines and a tendency to “bloom”, but nevertheless the set was working. But what did this indicate? First, I checked the copper tracks for continuity and corrosion in the feedback or chassis side of the EHT overwind but everything looked OK and the circuit is quite simple. I then checked the 30V input to R3565 and the 15V on the aquadag of the CRT. I also checked the beam limiting connection to the contrast control – R3440 and D6440 were both OK, as was the connection to the east/west generator via R3473, 680Ω. There wasn’t much else to check – only four capacitors and two resistors. A quick DC check showed that the capacitors hadn’t gone leaky and I was beginning to think that perhaps one had changed its capacitance value. Still, while I had the ohmmeter in my hand, I decided to check the two 1MΩ resistors (R3563 & R3564) – they may have gone open circuit. As it turned out, I needed to make three or four measure­ments on these two resistors (with them out of circuit) before I could believe my eyes – they both read 2.83kΩ! I initially thought that my digital meter had gone on the blink but it was working correctly. How bizarre that not one but both resistors had gone almost short circuit – from 1MΩ down to 3kΩ. How could this be? I fitted two new high-voltage resistors and resoldered the D lead which restored a normal picture and fixed the set. Howev­er, I found it hard to believe that these two resistors could behave in such a manner. Both resistors looked like the old-style IRH type. I thought that perhaps salt spray on the outside might be the cause but even after washing them, they were still low re­sistance. Anyway, suitably chastened, I humbly returned the set to Tim and was discretely silent when it came to crowing about the repair. The real question is have I learnt anything here? Probably not! The NEC monitor Owners of NEC monitors are gen- Items Covered This Month • Philips KT3-A3 TV Set. • NEC JC-2002VM 5D Monitor. • Brion­vega TVC 9203 Stratos 2 TV • Set. Sanyo VHRD-7770M VCR. erally fairly serious comput­er users. Certainly, these monitors enjoy a reputation for excel­lent performance and as a result, I am often asked to fix them long after they are really obsolete. So it was that I was asked to repair a 9-year old 20-inch (48cm) NEC Multisync 5D monitor, model JC 2002VM, which was dead. The first major problem with NEC monitors is the sheer quantity of metalwork that has to be removed before one can gain access to the electronics. However, I eventually reached the power supply – a switchmode type August 2000  39 Fig.1: part of the circuit for NEC Multisync 5D monitor. Transistors Q8A1 and Q8A2 are on the left, with IC8A1 to their right and capacitor C8A6 above it. It took some time to discover why resistor R8A1 (on the base of Q8A1) was burning out. – to find power going in but nothing coming out. But was this because the load was short circuit or was the failure in the supply itself? DC measurements at the power supply’s K terminals quickly established that there were no shorts on either the 170V (K1), 85V (K2) or 24V (K3) outlets, so that eliminated the short cir­ cuit theory. This meant that the supply itself had to be cactus. Being a quality product I was able to acquire a copy of the service manual, which is an impressively thick one, giving an immense amount of detail, including fault flow diagrams and circuit descriptions. Unfortunately, though, there wasn’t much on the power supply. The important thing it did tell me was how to run the power supply outside the set. This involved using a dummy load and disconnecting PTC TH601 in the degaussing circuit, to avoid damaging things further. Getting at the components on the power supply board meant not only removing it from the monitor but also removing the heatsink surrounding it. Anyway, the inside all looked fairly conventional and I started by checking the electros, most of which turned out to be very leaky, their electrolyte spilling onto the PC board. The worst one was C631 on the 24V rail. I re­ placed these and also checked any high-value resistors. Apart from the odd suspicious joint, everything else looked in order and I felt confident that it would work correctly back in the monitor. Alas, it wasn’t to be – the set was still completely dead with no output from the K terminals. As everything 40  Silicon Chip else had looked OK on the power supply, the most likely thing left was IC607 (SI-9509). I looked in the service manual for the spare part number but there wasn’t one. Alarm bells began to ring when I realised that the only part number listed was for the entire power supply assembly. I phoned NEC to be told there were never any spare parts available for the power supply and even the power supply itself was no longer available, new or exchange. I then tried various other IC suppliers for the SI-9509 but had no luck with any of them. It was looking as though the whole monitor was destined for land fill. However, having already spent time and money on this project, I was reluctant to leave it at that and so I decided to attack it more diligently. I removed the PTC (TH601), fitted a 100W globe on the 170V rail with a meter, connected a Variac to the bridge rectifier (D611) and wound the voltage up. I noticed that, from about 120V up, the output was pulsat­ing slowly but right up to full output. I wasn’t certain whether all the rails had to have dummy loads – especially the 24V and 85V rails – but this is where I had a break. When I connected a dummy load to the 24V rail, there was initially no output. As mentioned earlier, to get to the components it is neces­sary to remove a large heatsink/cover which is supported by three other heatsinks, with devices bolted onto them. One of the end heatsinks carries only a diode (D612). This a rather strange package, because it appears to be a three legged diode; something of a contradiction in terms. In fact, it is two diodes with their cathodes tied together but with separate anode connections, thus accounting for the three legs. As used here, the two anodes are connected together externally, making it simply two diodes in parallel. The above physical arrangement puts a lot of strain on the device’s three legs, when the large superstructure is removed. In the process of working on it, I had fractured the middle leg. After resoldering it and carefully reassembling the heatsink cover, I turned the variac up and found that all the outputs reached their correct levels. Now it was time to put it back in the monitor and fire it up. This time I had a result. The green power LED lit on the front control panel and EHT noises could be heard but even with a computer connected there was still no picture. Closer examination revealed that none of the picture tube heaters were alight. These are powered by 6V from the video board at the rear of the monitor which, when measured, was down to only a few volts. Following the circuit, this low voltage level re­ mained right through to transistor Q8A7 (2SK­701) and to the emit­ter of Q8A1 (2SD­882). However, the collector of Q8A1 was correct at 24V and it didn’t take a mental giant to suspect resistor R8A1 (33Ω) to the base of Q8A1, which turn­ed out be cooked and open circuit (ie, these was no base drive to Q8A1). Replacing this resistor restored the picture and I pro­nounced the monitor problem solved. Of course, I checked SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.premierbatteries.com.au August 2000  41 all the rails before finally replacing all the metal screening. My theory was that the failure of C631 and other capacitors put a lot of stress on the 24V rail, causing R8A1 to fail. In any case, it was very satisfying to save this otherwise excellent monitor from the tip. The set bounces At least, that was how I felt for the next couple of weeks. Then I was embarrassed by being recalled to this same monitor. I had soak tested the machine for several days after the repair and I was quite satisfied that everything had been fixed. But apparently not and the owner was now complaining loudly of the same fault. According to the owner, he hadn’t reinstalled the monitor for a couple of weeks after collecting it and this was the reason why he hadn’t complained earlier. Anyway, when I got it back in the workshop, I noticed that the green power LED remained on. Also, there was still EHT but no heater filaments. I immediately went back to resistor R8A1, which was burnt out again. I 42  Silicon Chip checked everywhere for a short circuit but none was to be found. Replacing the resistor restored the picture but the real mystery remained. I carefully checked the unit for solder dags or loose wires that might be causing a short but could find nothing. The re­placement resistor I had fitted was of a higher wattage than the original and it had still cooked, yet all the voltage rails were spot on (24V, 12V and 6V). I left it for a few hours and then, as I had to go out, I switched it off. The phone rang at that point and my engagement was post­poned, as it turned out to be inconvenient for my client. I went back to the monitor and switched it on. Immediately the resistor started to smoke and the voltmeter monitoring the 12V rail start­ed to dip. I turned it off quick-smart. Once again, I closely examined both the CRT board and the video board but there were no signs of stress or a measurable short circuit anywhere. It was strange – sometimes the rail would be fine and sometimes the resistor would start to get very hot. This went on for a few days, during which I removed the CRT socket panel and resoldered any suspicious joints. Eventually, I realised that this was not the area where the trouble was, be­cause the resistor would sometimes smoke even with the board totally disconnected. In fact, it would do it with everything disconnected from it except the input X plug. I suppose I should have worked this out sooner than I did but it is always easy in hindsight. I did notice that zener diode ZD8A3 was slightly disco­loured and I couldn’t quite figure out why that should be, as it appeared to be in an unaffected part of the circuit which in­volved minimal current and voltage. Finally the penny dropped. Ahh, Ahh! – an electrolytic, C8A6, sits right above it and was leaking electrolyte onto it. C8A6, C8A7 and C8E1 were all black Rubycon electroly­tic capacitors rated at 470µF 35V and all were leaking badly underneath. All the other electros were of a different brand and showed no signs of leakage. Zener diode ZD8A3 is supposed to peg the voltage on pin 5 of IC8A1, the output of which (pin 7) drives the base of Q8A2. Q8A2’s collector, in turn, drives the base of Q8A1 and resis­tor R8A1. Which was where we came in! Cleaning up and replacing these three capacitors finally fixed the problem properly and hopefully this will be the last I will hear of it. As I said at the beginning, “It doesn’t pay to be smug.” Whatsa matter you? Brian who? When Mario Roberto started talking about Brian Vega in his strong Italian accent, I felt sure he was referring to a friend. As it turned out, his “friend” was an expensive, top-of-the-range, Italian-made 71cm Brion­ vega TVC 9203 Stratos 2 TV receiver, which no longer worked. Not only was the set broken but the parts and service manual were no longer available and the company was defunct. He was very overwrought and I sympathetically agreed to have a look. I attacked it in two ways. First, I got onto the Internet and searched for the brand. After a lot of surfing, I eventually had a reply from Electronic Service S.N.C. who very kindly sent me a copy of the circuit. Second, I looked inside the set and noticed that it looked very much like a Thomson in its construction and layout. I initially spent some considerable time resoldering suspect joints but eventually came to the conclusion that the horizontal output transformer (TR2) was faulty. Transistor T15 (BU508A) was getting very hot, there was severe ringing on waveform 19 at its collec­tor and the 148V rail was very low. The next problem was replacing it. The part number was 523 99 0711 but pursuing it seemed to be a futile exercise as the manufacturer no longer existed. To my surprise, quoting this part number helped my parts wholesaler come up with a Siemens equival­ ent designated D210/37 (it’s also similar to the HR6288 or EHT6288 as in Nokia/ITT sets). And that was the answer. I was wellpleased that I had solved this problem and made its owner very happy. I just hope that I’m not doomed to become the local Brionvega “expert” – hopefully, there is only one such set in my vicinity. Actually, the set did make a reappearance some months later when it came in with a line across the screen. This time, the problem had to be in the vertical timebase, which is almost completely centred on IC5. I measured 29V and 200V feeding the IC but there was no output to the vertical deflection yoke. I replaced the IC and checked all the diodes but to no avail. It was about this time that I started to pay attention to transistors T11 (BD236) and T12 (BC238B) and wondered what they did. Well, I’m still wondering but I checked them anyway and though the transistors were OK, R110 (150kΩ) was high, causing both T12 and T11 to be switched off. This in turn deprived pin 14 of its 29V rail. Replacing R110 fixed the fault and restored the vertical output. But why? – is this circuit an attempt to prevent picture blooming and compensate for changes in voltage rails? Your guess is as good as mine. A bizarre problem I had a bizarre problem with a August 2000  43 Sanyo VHRD-7770M VCR of Middle East extraction, which meant it was a multi-system model (PAL/NTSC/ SECAM) using a P88/89 mecha-deck. The initial problem was that the set was just dead. A quick examination of the power supply showed it was time for a complete replacement of all the electros, as most were leaking. Not unrea­sonably, one could be forgiven for thinking that that would fix it all up. Well, it nearly did. The set now powered up but then closed down, leaving the display partially on with most characters either dim or not showing at all and displaying four zeros and the date. It was then that I noticed that if the system was moved off the AUTO position to SECAM, it would actually load a tape and even wrap it around the drum but neither the capstan nor the drum motors would work. This meant that there were no functions other than eject. I didn’t have the appropriate service manual for this model but was working from manuals for similar models – or nearly similar. I felt that the fault involved a mechanical timing problem involving the ejector, mode switch and loading motor. I replaced the belts and checked the gear timing very carefully but wasn’t getting anywhere. It was while measuring voltages on this module that I no­ticed that the switched 5V rail dropped to only 1.2V in the auto mode. Finally, I measured Q5402 (2SC44 84s) and found that it was virtually short circuit. Replacing it fixed the problem. It appears that, in the AUTO mode, additional power hungry circuits brought on-line caused the 5V rail to SC drop significant­ly. MORE FROM YOUR EFI CAR! EFI TECH SPECIAL Own an EFI car? Want to get the best from it? You’ll find all you need to know in this publication HERE ARE JUST SOME OF THE CONTENTS . . .  Making Your EFI Car Go Harder  Building A Mixture Meter  D-I-Y Head Jobs  Fault Finding EFI Systems  $70 Boost Control For 23% More Grunt  All About Engine Management  Modifying Engine Management Systems  Water/Air Intercooling  How To Use A Multimeter  Wiring An Engine Transplant  And Much More Including Some Awesome Engines! 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Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. 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Folded: $A5.95 inc p&p within Australia; elsewhere $A10 inc p&p. *BOOKSHOP TITLES: Please refer to current issue of SILICON CHIP for currently available titles and prices as these may vary from month to month. SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS AND SERVICES* *except subscriptions/renewals and Internet access Item Price Qty Item Description P&P if extra Total Price Total $A TO PLACE YOUR ORDER Phone (02) 9979 5644 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9979 6503 with your credit card details 24 hours 7 days a week OR Mail this form, with your cheque/money order, to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW, MARCH 2001  53 Australia 2097 * Special offer applies while stocks last. 08-00 Loudspeaker protector and fan controller for the Ultra-LD amplifier This simple project will save your valuable loudspeakers if a fault occurs in the output stages of the Ultra-LD Stereo Amplifier. As a bonus, it includes fan control so that the fan only runs when necessary. By PETER SMITH & LEO SIMPSON This loudspeaker and fan controller has been specifically designed to suit the Ultra-LD 100W per channel amplifier de­ scribed in the March and May 2000 issues. Not only does it pro­vide muting at switch-on and switch-off to prevent any thumps 54  Silicon Chip from the loudspeakers, it also protects the loudspeakers against catastrophic failure in the amplifier. In addition, it provides temperature control for the fan-cooled heatsink, switching the fan on if the heatsink temperature rises above 60°C. However, while the circuit has been specifically designed to suit the above amplifier, it can be used to mute and protect the loudspeakers in other amplifiers and also provide fan switch­ing if that is required. This is not the first loudspeaker protector we have pub­lished as we featured similar designs in April & October 1997. However, this latest design provides two methods of temperature sensing for the fan control as well as a temperature cutout for the speakers, if the heatsink rises above 80°C. Why you need protection By the far the biggest reason for incorporating speaker protection into Fig.1: each channel of the amplifier is connected to one of the moving contacts of the double-pole relay and is monitored for DC faults by a triplet of transistors, Q1, Q2 & Q3 for the left channel and Q4, Q5 & Q6 for the right channel. Two methods of temperature sensing for the fan control are shown. The section in the bottom lefthand corner of the circuit shows the optional thermistor temperature sensing, using an LM393 comparator. any amplifier is for insurance – to save money in the case of a serious amplifier fault. For example, in the Ultra-LD amplifier, the main supply rails are ±55V DC. If one of the output transistors fails it means that more than 50V DC will be applied to the speaker’s voice coil. For a nominal 8Ω speaker the voice coil will have a DC resistance of around 6Ω and so the total power dissipation will be around 400W until the supply fuse blows. But maybe the fuse won’t blow. Either way, the speaker is likely to be history. On the one hand, the huge DC power applied is likely to push the voice coil right out of the gap, damaging the voice coil and suspension in the process. But a worse scenario is if the on-board supply fuse doesn’t immediately blow – a strong possibility since a current of around 8.5A may not blow a 5A fuse straight away. If the fuse doesn’t blow straight away, there is a strong possibility that the voice coil will immediately become red-hot and set fire to the speaker cone material. Now we are really in trouble because the acetate filling material in the enclosure and the grille fabric can also catch fire and then generate huge quantities of acrid black smoke. Don’t think this can’t happen. It has happened before and will happen again to some unsuspecting owner of high-power audio equipment. Stereo systems do fail and they can cause house fires. That is why they should not be left on for long periods of time, especially if no-one is present to turn them off if a fault does occur. OK, we have established the risk associated with any audio power amplifier of more than about 40W per channel. The way to avoid the problem is to build a loudspeaker protector like the one featured here. Apart from the fire insurance angle, the circuit will mute any thumps and pops which occur when you turn your amplifier on and off and it does the August 2000  55 The 80°C thermal switch is attached to the side of heatsink using self-tapping screws. A second 60°C thermal switch (for the fan) can be mounted next to it if you elect not to use a thermistor temperature sensor. fan control which we’ll come to later. The whole circuit fits onto a PC board measuring 124 x 60.5mm and includes a DPDT relay with 10A contacts, plus a 3-terminal regulator on a finned U-shape heatsink. Fig.1 shows the complete circuit. On the lefthand side of the circuit you will notice that each channel of the amplifier to be protected is connected to one of the moving contacts of the double-pole relay and then out to the speaker terminals. Each channel of the amplifier is also monitored for DC faults by a triplet of transistors, Q1, Q2 & Q3 for the left channel and Q4, Q5 & Q6 for the right channel. For the sake of simplicity, we’ll just talk about the left channel since the identical process occurs for the right channel. Let’s see how the triplet of transistors operate together. The active signal from the amplifier’s left channel is fed via a low-pass filter consisting of the 22kΩ resistors and two 47µF BP (bipolar or non-polarised– NP) electrolytic capacitors. The filter network removes any audio frequencies and just leaves DC to be monitored by the three transistors. This is because we don’t want audio signals to trip the protection circuit in any way. The line from the low pass filter is connected to the emitter of Q1 and the base of Q3. Q1 monitors for negative DC signals while Q3 monitors for positive DC sign­als. If a DC signal of more than +0.6V is present, Q3 will turn on. Similarly, if a signal of more than -0.6V (ie, neg56  Silicon Chip ative voltage) is present, the emitter of Q1 will be pulled low, and so Q1 will turn on and it will turn on Q2. Both Q2 & Q3 have a common 56kΩ collector load resistor and this normally feeds base current to Q7. Q7 feeds base current to Q8 and so both these transistors and the relay are on. But if Q1 or Q3 are turned on by an amplifier fault condition, the base current for Q7 is shunted away and so Q7, Q8 and the relay are turned off, disconnecting the speakers. As noted above, Q4, Q5 and Q6 do exactly the same monitoring for the right channel of the amplifier and they switch Q7, Q8 and the relay in exactly the same way. Heavy duty relay The relay selected for the job has contacts rated at 10A and there are several reasons for this. First, and most important, we want the contact resistance in the relay to be as low as possible so that it has negligible effect on the amplifier performance, in respect of distortion, damping factor and so on. Second, the relay contacts have to pass and break the heavy DC currents which would otherwise flow through the loudspeaker if a fault ever occurs in the amplifier. However, we don’t merely use the relay to disconnect the amplifier’s output from the loudspeakers. If we simply did this, there is a fair chance that the contacts would just arc across and the heavy DC current might continue to flow through the loudspeaker. That might seem unlikely but when you have a heavy DC cur­rent and a high DC voltage pushing it along, it can be quite hard to break the circuit. That is why the moving contacts of the relay are shorted to the loudspeaker ground lines via the “un­used” contacts. By shorting the moving contacts of the relay to the loudspeaker ground lines, the arc current is diverted to chassis and the fuses will blow if the arc still persists. Muting delay So far we have described the protection function of the circuit. Now we’ll look at the muting function, to prevent thumps at switch-on. This is achieved with resistors R1, R3 and the 220µF capacitor C1. When power is first applied, C1 is discharged and so no base current can flow to Q7 via 56kΩ resistor R1. C1 then charges via the 220kΩ resistor R3 and after three seconds or thereabouts, enough voltage is present to allow base current to pass via R1 to Q7. It then turns on Q8 and the relay to connect the loudspeakers. If power is removed from the protection circuit, the relay opens within less than half a second and this prevents any turn-off thump being heard. Fan control Fig.2: the speaker protection board is powered from the 35V secondary wind-ings on the Ultra-LD amplifier’s power transformer. We have provided two methods of temperature sensing for the fan control and both are shown on the circuit. The section in the bottom lefthand corner of the circuit shows the optional thermis­ tor temperature sensing, using an LM393 The leads of the thermistor are insulated with heatshrink tubing. It is then slid into a channel in the TO-220 heatsink clip, which holds it firmly in place. The thermistor/heatsink clip assembly is clipped onto one the fins of the large tunnel heatsink, as shown here. Be careful not to damage the thermistor body during this procedure. comparator. But first we’ll talk about the simple version of the circuit which involves a 60°C thermal cutout TH1 and transistor Q9. The thermal cutout is mounted on the tunnel heatsink, preferably somewhere near the centre. The thermal cutout has a set of normally closed contacts but when the temperature rises above 60°C, they open and this allows the associated 2kΩ resistor to turn on transistor Q9 and thereby run the fan. It is fed via a 33Ω 5W resistor so it does not run at full speed but still pumps a fair amount of air through the tunnel heatsink. When the heatsink temperature cools down to around 40°C, the thermal cutout will close again and the fan will be switched off. Note that 40 degrees C is relatively cool so the fan will probably run for a long time and on a hot day would continue to run until the amplifier was switched off. While the thermal cutout has the virtue of simplicity, its relatively wide hysteresis (ie, difference between switch-on and switch-off temperatures) means that once the fan comes on, it may not turn off until the amplifier is switched off. Thermistor circuit As an alternative to the thermal switch, we have provided the optional thermistor circuit mentioned above. This uses a negative temperature coefficient (NTC) bead thermistor in a comparator circuit based on an LM393, IC1. Pin 2 is connected to the thermistor (RT1) while pin 3 is connected to trimpot VR1. Naturally, the thermistor is mounted on the tunnel heatsink. At room temperatures, trimpot VR1 will be set so that the voltage at pin 3 is below that at pin 2 and so the output at pin 1 will be low. This means that transistor Q9 will be off and the fan is not running. When the heatsink temperature rises, the resistance of the thermistor goes low and at some point pin 2 will be pulled below pin 3 of IC1. This will cause pin 1 to go high (or actually, the open-collector transistor inside IC1 to turn off) and allow Q9 to turn on and run the fan. The 1MΩ positive feedback resistor between pins 1 & 3 of IC1 ensures a degree of hysteresis so that the fan does not cycle on and off repeatedly. We suggest that VR1 be set to turn on the fan for heatsink temperatures of around 55-60°C. We’ll discuss that setting later on in the article. Finally, there is another thermal cutout in the circuit and that is in series with the base of Q8, the transistor controlling the relay. This second thermal cutout is a failsafe device so that if the amplifier is overheating due to a serious overload or a failure of the fan circuit, the relay will be turned off to disconnect the loudspeakers. Power supply Deriving a low-voltage supply from that of the Ultra-LD Amplifier presents a problem because of the August 2000  57 The loudspeaker protection module was mounted inside the disk drive cage of the Ultra-LD Amplifier, adjacent to the power amplifier module. Note that the heatsink gets quite hot, so make sure it goes towards the top. relatively high AC voltage from the transformer secondary and the need to provide a total current of around 200mA at 12V to power the fan and relay. Our solution is to connect diodes D1 & D2 to the 35V secondary windings (as shown in Fig.2) and then pass the full-wave recti­fied DC from the 470µF capacitor via a 33Ω 5W resistor to the input of an LM317HVT high voltage 3-terminal regulator, REG1. This provides a regulated 11.7V to power the speaker protection circuit. PC board assembly All the parts are mounted on a PC board measuring 124 x 60.5mm and coded 01108001. The wiring diagram is shown in Fig.3 and it shows both temperature measurement options; ie, thermal cutout TH1 and the optional thermistor, RT1. If you are going to use thermal cutout TH1, you can leave out IC1, VR1, RT1 and the associated resistors apart from the 2kΩ resistor which supplies base current to Q9. Mount the PC pins first and make sure they are a tight fit in their holes before they are soldered. Then fit the links (these must be done before the two wirewound resistors are in­ stalled). Most of the resistors and diodes are mounted vertically (end-on) to save space. Mount them as shown in the diagram of Fig.3. In each case, do not mount the end-on diodes and resistors so that they are right down on the board; you should have a lead length of about 2-3mm above the board to make sure the component is not overheated while being soldered. The two 33Ω 5W wirewound resistors should be mount­ed so that they are about 2-3mm above the board, to allow cooling. The four 47µF electrolytic capacitors can go in either way around since they are non-polarised (BP or NP). The other elec­trolytics are polarised and must be inserted the correct way around. Next, insert the IC and the transistors and make sure you put the correct one in each spot. The relay is intended for mounting in a socket but we have not used a socket in this case, because it takes up more space on the board and it will be an extra source of contact resistance which we particularly want to avoid. Therefore the relay is mounted by soldering short lengths of stout (say 1mm) tinned copper wire to each relay pin. These wire leads are then pushed through the relay mounting holes in the PC board and soldered. Alternatively, if you are supplied with a PC board which has slotted holes for the relay, you can solder it in directly. The 3-terminal regulator is mounted on a U-shaped heat­sink using a standard insulating kit (see Fig.3) This assembly is then attached to the PC board with two M3 screws, nuts and washers, and the regulator leads soldered. Installation When the PC board is complete, check your work carefully. If you Resistor Colour Codes             No. 1 1 1 2 4 3 2 1 1 2 2 58  Silicon Chip Value 1MΩ 220kΩ 68kΩ 56kΩ 22kΩ 10kΩ 2kΩ 1.5kΩ 240Ω 22kΩ 33Ω 5W 4-Band Code (1%) brown black green brown red red yellow brown blue grey orange brown green blue orange brown red red orange brown brown black orange brown red black red brown brown green red brown red yellow brown brown red red orange brown not applicable 5-Band Code (1%) brown black black yellow brown red red black orange brown blue grey black red brown green blue black red brown red red black red brown brown black black red brown red black black brown brown brown green black brown brown red yellow black black brown red red black red brown not applicable 56k 1.5k 56k 10k HEATSINK TH2 80C VR1 50k 10k 1M 220k Q5 68k Q9 2k 10k 220F 220F 10F 0.1F Q7 IC1 A LM393 D3 K 1 Q2 Q4 470F Q1 Q6 33 5W A 33 5W K NOTE: CAPACITORS MARKED "BP" ARE BIPOLAR 47F BP 47F BP 22k 22k 22k 22k Q8 D2 LED1 FRONT PANEL POWER LED REG1 LM317HVT 240 K A 2k D1 Q3 K Fig.3: both temperature sensing options are shown on the wiring diagram. If you are using thermistor TH1, you can omit IC1, VR1, RT1 and the associated resistors apart from the 2kΩ resistor which supplies base current to Q9. TO LEFT SPEAKER 47F BP RLY1 22k 1W _ 22k 1W + FROM LEFT AMP FROM RIGHT AMP TO RIGHT _ SPEAKER + 47F BP + _ + _ A Parts List M3 x 10mm SCREW HEATSINK INSULATING PAD PLAIN WASHER INSULATING BUSH REG1 MOUNTING DETAILS TO 12V DC FAN RT1 TH1 60C LM317 0V FROM T1 SECONDARY 35V 35V M3 NUT HEATSINK _ + HEATSINK have a DC power supply capable of around 15-20V then you can do some initial checks which we describe in the setup procedure below. Your DC supply can be connected to the input of the 3-terminal regulator. Failing that, your next step is to install the board in the amplifier case. You can see from the photos how we mounted the prototype. Quite a lot of wiring is involved in the installation. You will need to run three wires from the 35V transformer secondary windings, two wires to the 12V fan and another two pairs of wires to the thermal cutouts (TH1 & 1 PC board, code 01108001, 60.5 x 124mm 1 10A 240VAC DPDT power relay (Jaycar SY-4065) 1 Universal “U” heatsink (Jaycar HH-8511) 1 TO-220 clip-on heatsink to mount thermistor (Jaycar HH-8504) 1 TO-220 insulating bush and washer 16 PC stakes 9 M3 x 6mm screws 2 M3 x 10mm screws 3 M3 nuts 7 M3 flat washers 4 M3 x 10mm tapped spacers 1 50kΩ horizontal trimpot (VR1) 1 Thermal circuit breaker, 80°C, normally closed (TH2) (Altronics S-5610) 1 Thermal circuit breaker, 60°C, normally closed (TH1) (Jaycar ST-3821, Altronics S-5600) 1 NTC thermistor, 100kΩ <at> 25°C (RT1) (DSE R 1797) Wire and cable 200mm length of 0.8mm tinned copper wire; hook-up wire; heavy-duty speaker wire Semiconductors 3 1N4004 1A 400V diodes (D1-D3) 1 LM317HVT high voltage adjustable regulator (REG1) 1 LM393 dual comparator (IC1) 5 BC547 NPN transistors (Q1, Q3, Q4, Q6, Q7) 2 BC557 PNP transistors (Q2,Q5) 1 BC327 PNP transistor (Q8) 1 BC337 NPN transistor (Q9) Resistors (0.25W, 1%) 1 1MΩ 3 10kΩ 1 220kΩ 2 2kΩ 1 68kΩ 1 1.5kΩ 2 56kΩ 1 240Ω 4 22kΩ 2 33Ω 5W 2 22kΩ 1W Capacitors 1 470µF 63VW PC electrolytic 2 220µF 16VW PC electrolytic 4 47µF 50VW non-polarised PC electrolytic 1 10µF 63VW PC electrolytic 1 0.1µF 63VW MKT polyester Miscellaneous Heatsink compound. August 2000  59 +11.7V is present at pin 8 of IC1, at the emitter of Q8 and the collector of Q9. Initially the fan should be off. The relay should operate about three seconds after turn-on. When the relay is closed, LED1 should be alight. To check that the fault protection works, connect a 1.5V battery to the left and right channel inputs on the protection PC board. In each case the relay should open immediately, indicating that the protection circuit is working correctly. Fig.4: this is the actual size artwork for the PC board. Check your board carefully before installing any of the parts. TH2). By the way, the wires to TH2 also connect the front panel LED, as shown on Fig.3. You also need to run the heavy cabling from the amplifier outputs and to the loudspeaker terminals. Since so much extra speaker wiring is required you must use heavy cabling such as 2 x 79/02mm speaker cable (or heavier) to avoid power losses and any reduction in amplifier damping factor. However, do not make the speaker cable connections to the PC board until initial checks are done. We’ll come to these in a moment. If you are using the bi-metallic thermal cutouts you will need to mount them somewhere near the centre of the tunnel heat­sink. Our photo shows just one thermal cutout (TH2). The thermistor option is actually easier because you can just use a TO-220 clip-on heatsink (Jaycar HH8504) to mount the thermistor. We have a series of photos showing how the leads of the thermistor are individually sleeved and then a TO-220 clip is used to secure the thermistor to one of the fins of the tunnel heatsink. Setting up With all of the wiring complete, apart from the speaker cabling, it is time to power up the protection board. First check that the output of the 3-terminal regulator is around +11.7V. You can also check that Temperature setting Ideally, VR1 should be set so that the fan cuts in at around 55-60°C. To do this setting you need a thermom­ eter which will read to 100°C. Our suggestion is to boil some water in a jug and then add it slowly to a small container of water while stirring it with the thermometer. As it comes up to 60°C, you can adjust VR1 to turn the fan on. Oh, you will of course have to immerse the thermistor in the water container for this adjustment. The thermistor and its leads should be sealed into a small plastic bag or plastic shrink-wrap. Once you are satisfied with the adjustment of VR1, you can clip the thermistor back onto the heatsink fin, connect the loudspeaker cables and SC the system is ready to roll. Thumps In The Ultra-LD Amplifier As published in the March & May 2000 issues, the Ultra-LD 100W amplifier does produce a thump several seconds after switch-off although it does not sound particularly loud. However during our testing of this loudspeaker protection circuit, we noticed that if the power was turned on and then off fairly quickly, there was quite a sharp turn-on thump as the relay reconnected the loudspeakers. This was puzzling as normally there is very little turn-on thump from this amplifier. We then connected up our digital scope to monitor the output of one amplifier channel, both before and after the relay. Setting the timebase to 0.5 sec/div, we were able to easily 60  Silicon Chip observe what was going on. When the amplifier was turned off, it did produce a turn-off thump which was muted by the delay cir­cuit. However, the turn-off thump was really quite severe, amounting to a 20V spike which then decayed to zero over a period of 20 seconds or more. So if the power was reapplied shortly after turning off, the mute delay capacitor had not had enough time to discharge and it connected the amplifier before it had time to stabilise again, producing a sharp thump. Having seen just how severe the turn-off thump was, we realised it was due to the regulated -55V rail collapsing prema­ turely. This was due to the fact that the current drain from the -55V rail is higher than from the +55V rail. The solution was to increase the 100µF 63V capacitor connected to the -55V rail on each amplifier board, to 220µF. This change means that the input differential stage (Q1, Q2) maintains control over the amplifier DC conditions for much longer so that the main ±52.5V rails are almost completely discharged before the amplifier ceases to work. The result – no turn-off thump. So regardless of whether you build this protection circuit of not, we recommend that owners of the Ultra-LD amplifiers increase the 100µF capacitor for the -55V rail on each board to 220µF. WHY??? would you bother building a CFL inverter kit when we have 13W CFLs that run on 12V DC These CFL's must not be installed in 240V AC sockets. (Edison Screw), centre positive. Equivalent to a 75W incandes-cent lamp. 180mm long, 47mm maximum base diameter: (CFL12) $20 12V+ ATX PC POWER SUPPLY: These NEW 90W LITEON Brand power supplies include logic level controlled mains switch and have the following outputs +5V <at> 10A, -12V <at> 0.2A, +12V <at> 1.5A, +3.3V <at> 6A. Input is 100-240V AC <at> 5060Hz via an IEC socket. Has internal fan. Unit weighs 1.3kg and measures 140 x 150 x 85mm: (PATX1) $15 GND 650nm VISIBLE LASER DIODE MODULE: Visible laser diode, diode housing, driver circuit, and collimation lens all pre-assembled in a small module. Features an auto power control circuit (APC) driver, Req. 3 to 4.5V <at> approx 50mA. Overall dimensions: 12mm X 34mm long. Bright enough for a Laser Light Show: (LM2) $10 NEW PRODUCTS CMOS CAMERAS SUPER MICRO B/W Low light (0.2 Lux) Low intro price $99 L AL SM mm 17 X mm 60 B/W SUGAR CUBE(& NOW AVAIL ABLE IN COLOUR) SIZED CAMERA DRAWN ACTUAL SIZE The smallest monochrome m camera we have offered yet. 4m They don’t have the greatest 1 X resolution but are very small 6 & only draw 10mA <at> 5V X1 (a 9V bat. + regulator would 16 run one of these for days) B/W Camera in a plastic housing & suitable power adaptor for special intro price...$70 C O L O U R S U G A R C U B E CAMERA...$130 HIGH QUALITY VHF MODULATOR TO SUIT $2 WITH CAMERA PURCHASE ONLY. CHECK OUT “CAMERAS” ON OUR WEB SITE IMPORTANT NOTICE SUPER SPECIAL AUGUST / SEPTEMBER PRICES CHEAP PENTIUM STOP PRESS MOST OF THE PRICES IN THIS AD ARE SPECIAL PRICES FOR THE MONTHS OF AUGUST AND SEPTEMBER ONLY. PLEASE QUOTE THESE PRICES WHEN ORDERING PA N / T I LT D U A L S E RV O CONTROLLER KIT: Ref. SC Jan 1998. WE HAVE FRESH STOCKS OF NEW 12V This kit can be used to control two model radio control servos such as our MS1 / 7Ah GEL BATTERIES servos. Two servos can be configured to Priced at a fraction rotate & pan a small camera (these parts of their real value. not included in kit). PCB measures 63 AAHTTRY are 7 65mm X 150mm x 48mm and operates from 9-12V DC. The V 12L CELL B X 94mm ,with kit includes a PCB, all the on-board L GE components, pushbutton, potentiometers, suitable trickle knobs, plastic case & a label: (K114) $19 charger. $25 KEYCHAIN LASER POINTER 650nm: Supplied in a small metal cylindrical case that is fitted with a keychain. Powered Switchable by 3 LR44 cells (supplied):(LPM2) $11 120/ 230V AC input. DC outputs are +5V<at>6A, +12V<at>1A, - VIDEO CAMERAS CCD B/W 12V<at>1A, -5V<at>1A. Circuit provided, RU CAMERA approval. Modern design. Mains input - IN SWIVEL CASE Not for the inexperienced ! Be quick: (PS6) $99 4 for $24 PCB VIDEO CAMERAS MOSFETS: B/W CCD CAMERAS $89 IRFZ44:60V / 50A pinhole (60deg.), 92 deg,120 deg. (N channel, TO-220), add $10 for 150 deg. 0.028ohm on resistance: $2.50 each 2 MOTOR LASER LIGHT SHOW KIT IRF540: 100V / 28A Kit includes very bright laser module, all (N channel, TO-220), electronic components, two high quality 0.077ohm on resistance: motors plus front surfaced mirrors. All that $2.50 each is required is a little bit of skill for the POPULAR MOSFET PAIR assembly. Simple construction with no MTP3055 & MTP2955 any mix 10 for $10 PCB required. $20 COMPUTER POWER SUPPLY: New complete PCB assembly only. Overall dimensions are 45 x 108 x 200mm. PHONE CALL SCREENER / DTMF DECODER KIT: Ref. EA February 2000. With the an Answering Machine & this kit you can build a phone Call Screener, a Remote Operated Relay via the phone or a Keyless / Keypadless DTMF Alarm Switch. This kit does not connect to the phone line, it uses an Electret Microphone (mains ents, Electret Microphone, plastic box, BRAND NEW GERMAN MADE MOTOR pushbutton, plugpack, label and a AND GEARBOX. speaker: (K153C) $42 This is a 24V motor but runs well with plenty of torque at 12V and starts at 2-3V. NEW AUSTRALIAN The out put shaft is 10mm dia. and the PLUG PACKS AT BELOW motor is 60mm dia. X 94mm long. We WHOLESALE PRICES believe these are made as truck GENERAL ELECTRIC 20VA windscreen wiper motors. This motor is 14VDC <at> 700mA..... worth well over $100, But as a special for AUDIOVOX 9V <at> 500mA August and Sep. AUDIOVOX 12V 2000 only... <at> 400mA.... just $20 $5 Ea. or 5 for $20 9V <at> 1A $9 More motors on our website UHF AUDIO / VIDEO TRANSMITTER KITKit includes all components needed. PCB plus all on-board components, connectors, switch, metal case, telescopic N e w 1 2 V - 2 4 V i n v e r t e r u n d e r antenna, twin RCA A/V lead, all that is needed to complete the full kit. 12Vdc development. 20ADC motor speed controller kit (K98) <at>10mA operation. when purchased with the above motor $14 Ideal for transmitting audio and AUTOMATIC LASER LIGHT SHOW KIT: video around you MKIII. Changes patterns every 5 - 60 secs. home.. Complete suitable Countless great displays from single to Kit for just $28 plugcack $5 multiple flowers, collapsing circles, rotating single & multi ellipses, stars, etc. 3 LED LOGIC PROBE KIT: Kit inc. PCB, all on board comp-onents, (Ref. SC May 1998) Ideal for tracthree small DC motors, mirrors, precision ing digital / logic faults and powered by the circuit under adjustable mirror test. Includes PCB and mounts & all on-board components, laser module. LED's and a surplus (K115) Kit with laser module $50 case $15 plastic case which a special for August & September 1995. measures 35 x 24 x 123mm: (K119) $7 NIGHT VISION UPGRADES & MORE Be quick to find the following & many more items in the "BARGAIN CORNER" of our website ....... SIMPLY SPEAKING VOICE SOFTWARE plus headset: $25, PENTIUM NOTEBOOK COMPUTERS: $700, PENTIUM MOTHERBOARDS: $90, PENTIUM 11 COOLER FANS: $3, TV/FM/CAPTURE CARDS with infra red remote controls: $160, TEKRAM SCSI CONTROLLERS: $90, POWERWARE 3115 300VA UPS's: $220, NET 450VA UPS's: $300, VGA CABLES: $3, TELEPHONY COMBO 33.6K MODEM CARDS: $35, 5V/3A S W I T C H E D M O D E R E G U L AT E D POWER ADAPTORS: $12, SCANNER ASSSEMBLY with electronics /lens /mirrors: $12, etc., etc. VISIT: www.oatleyelectronics.com DOOR / WINDOW ALARM Small, simple, easy to mount, operates when a door or window is opened, has very loud electromechanical siren, mounting screws provided, has OF-ON BRAND switch, needs 2 X AA batteries (Not provided): $3.50 Radar STEPPER MOTORS SANYO DENKI (Step Syn) Type 103770-6942, 4wire, main body is 67mm diam. by 51mm long, 1.5A / 4.5V, 1.8deg. steps, 0.46KG,: $15 GEARED AC MOTORS Brand new small mains operated geared motors, very strong, made for rotating microwave turntables, 240V/ 50Hz/3W/5RPM., $4Ea. or or 4 for $12. 35-140 LED INFRA-RED ILLUMINATOR KIT Comes on when it gets dark or can be controlled by alarm system. 20-30M range Kit inc. mounting tray & universal swivel mount. 35 LEDs $25. Extra 35 LED pack (3extra packs max) $14 per pack. 140 LED kit: $67 OR base Kit + 105 extra NEW 500W Tungsten Halogen Lamps LEDs, 140 LEDs TOTAL!!! for just $50. (All are new but packing may be shop Use with B/W cameras to see in the dark. soiled) Ideal replacement or spare bulbs ONE / TWO CHANNEL UHF REMOTE for yard and security lights. $2ea CONTROL On freq. of 304MHz, transmitter is (USED) POCKET PAGERS: Small assembled, modern pagers, brands include LINK, receiver is a kit, inc. 2 12V/ PHILIPS, RTC. Condition “unknown”, all 12A relays, 1Tx + have two small (grain of wheat) 1.5V 1Rx kit:$45, additional Tx: $15 lamps and lots of other parts. All are I CHANNEL Kit just $25 powered by one 30 Minute MECHANICAL TIMER: AA cell. With normally open contacts (089910) (closed when timing). Timer 5 for $5 "DINGS" at the end of timing. Some with micro vibration motors $5ea Ideal for battery chargers or exposure timers: (GMT2) $4 MASTHEAD AMPLIFIER KIT SPECIAL The MAR-6 available separately $4. 12 HOUR MECHANICAL TIMER: The amplifier gives good results 55 x 48 x 40mm, 5mm with any two metal wires or shaft (knob not supplied), strips acting for the antenna. It two hours timing per 45 degree rotation. Two should even work with a coat25V / 16A SPST switches hanger! Basic kit with both (normally closed contacts - open when the PCBs & all on-board timing) which close at the end of the timing parts (K03) $15 ...Basic Kit + period: (GMT1) $4 2 Weather-proof Plastic Check out our “new look” Boxes + plug-pack: $24 (ask for your free case with this item) web site for more $25 products. Amazing cheap super bargains in our bargain corner. Some of our prices have changed as a result of GST & some as a result of the poor performance of the Australian dollar... www.oatleyelectronics.com Orders: Ph ( 02 ) 9584 3563 or 64, Fax 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 August 2000  61 major cards with ph. & fax orders, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 SC_AUG_00 Proximity switch for 240VAC mains lights Do you have a table lamp or standard lamp without an in­built mains switch? How would you like to turn the lamp on and off without even touching it? Now you can do it with this compact mains-operated proximity switch. Wave your hand near it to turn it on or off. Article By LEO SIMPSON Design By ALLAN BONNARD M AINS-OPERATED touch switches for light dimmers and table lamps are not new but up till now they have all involved a metal plate or exposed metal work which you need to touch to operate. This Proximity Switch circuit is different – there is no exposed metal plate; you just wave your hand near a concealed plate and hand capacitance does the rest, turning the circuit on and off. In practice the circuit is built into a small plastic case in series with the mains cord to the lamp. Alternatively, if the lamp base has space inside and is not made of metal, you could build the Proximity Switch right inside it. Before we go any further, this circuit 62  Silicon Chip design is not suit­able for permanent installation as a light switch in your house wiring. This is because it is a 4-wire circuit and a light switch is normally a 2-wire circuit. So how do you produce a Proximity Switch for 240VAC lights? It has been made possible by a new IC which is designed to work with a proximity sensor. The sensor is located behind the light switch pad, fully protected by a dielectric (ie, insulating) barrier. Thus the unit offers increased safety. The sensor works on a principle of “charge transfer sens­ing”, which has its origins back in the 1700s, when investiga­tions where first being made into electricity. A study of this was made by Mr William Watson in England and also by the renowned Ben­jamin Franklin. Charge transfer sensing In effect, the IC measures the charge on the sensor plate by transferring its charge to a charge detector with a known ca­pacitance value (Cs). This transferring is done using Mosfet switches internal to the IC. Now if the charge detector detects capacitance above a certain level, the output is triggered. This sounds relatively easy but there are some complica­tions. Firstly, the effective capacitance of the sensor plate can vary widely depending on the location and wiring configuration, so having a fixed threshold level for WARNING: ALL PARTS OPERATE AT 240VAC Fig.1: the circuit is based on a proximity sensor IC (QT116) which turns the Triac on or off in response to change in capacitance of the sensor plate. Note that all parts of the circuit run at 240VAC – they are live and dangerous. circuit switching would be useless. Instead the IC calculates the sensor plate capacitance at that particular location and then looks for sudden changes in this level to control the output triggering. Another problem that comes with this type of circuit is noise so the IC uses a burst mode to acquire the signal and check the level. For a valid detection, a series of four consecutive confirmations will be required before a detection is registered. Within the IC is a 14-bit single-slope switched capacitor Analog-to-Digital Converter (ADC). This optimis­es the burst length according to the buildup on Cs so that the circuit will not become swamped when high capacitance values are encountered. Circuit details Fig.1 shows the complete circuit. It is directly powered from the 240VAC mains supply via the 0.1µF 250VAC capacitor (C1) and 100Ω limiting resistor (R1). The reduced supply is rectified and regulated to 9.1V by zener diode D1 and then fed via diode D2 to the 100µF capacitor to provide a supply voltage of about 8.5V. This supplies transistor Q1 which provides the gate current to the Triac. The 8.5V supply is then fed via a 2kΩ resistor (R4) to zener diode D3 which provides a well-regulated 5.1V supply for IC1. The small sensor plate is connected directly to pin 7 of IC1 and also via a .047µF capacitor to pin 6. Each time the circuit is triggered, the output at pin 2 goes high to turn on Warning! All parts in this circuit (including the sensor plate) operate at mains potential (ie, 240VAC) and must be fully isolated from the user. Do not operate this device unless it is fully enclosed in a plastic case. Similarly, do not work on the circuit or touch ANY part (sensor plate included) while it is plugged into a mains outlet. We recommend that only experienced people build this design. Q1 and the Triac Q2, or low to switch both devices off. The Triac is turned almost fully on and so there is relatively little switching hash produced by it, which would not be the case if it was a conventional phase-controlled Triac circuit as used in a light dimmer. The Triac is rated up to 10A but this circuit is only suit­able for lamp loads up to about 300W since there is no heatsink for Q2 and the PC board tracks are not suitable for high cur­ rents. The 56Ω 1W resistor and .01µF capacitor across the Triac form a snubber network to protect it from switching voltage transients. PC board assembly There are two boards involved for this project, one for the sensor plate which does not have any components on it and one for the main circuit and this comes with a screen-printed comTo ensure safety, the circuit must be fully enclosed in a plastic case with no exposed metal parts. August 2000  63 Fig.2: the wiring diagram and component overlay. The whole assem­bly, including the sense plate, must be mounted in a plastic box for safety. ponent overlay which is also shown in the wiring diagram of Fig.2. First mount the IC socket and then the resistors, diodes, transistor and Triac and make sure that the semiconductors are installed the right way around. The capacitors can go in either way around except for the 100µF electrolytic which must be in­stalled with correct polarity. Do not place IC1 in the socket yet, as we will need to test the circuit first (see below). Next, attach the 4-way insulated terminal block to the PC board with two 6BA screws and nuts. Then use brown and blue 250VAC hookup wire to make the Active & Neutral connections from the PC board to the insulated terminal block. You then need to connect the sensor plate. This is done by soldering a small length of tinned copper wire to the appropriate pad on the PC board. This wire passes through the single hole in the sensor board when it is mated up to the main PC board and soldered. The sensor board is attached to the PC board with four 6BA screws and eight nuts, with nuts being used as spacers, as shown in the photos. Testing There are several ways to test the circuit and it is pre­ferable to do it at low voltage rather than at 240VAC. The pre­ferred method is to use a DC power supply set to an output of between 12V and 15V or thereabouts. Connect the negative lead from the supply to the Active 240VAC line in terminal. Connect the positive lead to the C1 capacitor side of R1 (100Ω 1W). Now use your multimeter to check the DC voltage between pin 1 Table 2: Capacitor Codes      Value IEC Code EIA Code 0.1µF 100n   104 .047µF  47n  473 .01µF  10n  103 22pF  22p   22 Table 1: Resistor Colour Codes  No.   1   1   1   1   1 64  Silicon Chip Value 3.9MΩ 2kΩ 470Ω 100Ω 56Ω 4-Band Code (1%) orange white green brown red black red brown yellow violet brown brown brown black brown brown green blue black brown 5-Band Code (1%) orange white black yellow brown red black black brown brown yellow violet black black brown brown black black black brown green blue black gold brown Parts List 1 PC board, 72 x 33mm 1 PC board (sensor), 52 x 34mm 2 2-way insulated terminal blocks 1 double-screw BP connector 1 plastic utility box, 85 x 56 x 40mm, DSE Cat. H-2874 or equivalent. 1 250VAC 3-core flex and moulded 3-pin plug 2 cordgrip grommets to suit power flex 6 6BA screws and 10 6BA nuts Semiconductors 1 QT116-D proximity sensor and Triac trigger (IC1) 1 C9013 NPN transistor (Q1) 1 BTA06 600C 600V Triac (Q2) 1 9.1V 1W zener diode (D1) 1 1N4004 1A 400V diode (D2) 1 1N4733 5.1V 1W Zener diode (D3) Capacitors 1 100µF 25VW electrolytic 1 0.1µF 250VAC metallised polyester 1 0.1µF monolithic 1 .01µF 250VAC metallised polyester 1 .047µF monolithic 1 22pF ceramic Above: the PC board assembly, complete with the sensor plate, is attached to the lid of the case using contact cement or a similar adhesive. This view shows how the sensor plate is mounted on the main PC board. The entire assembly is then glued to the case lid. DO NOT TOUCH the sensor plate or any other parts while the unit is plugged into the mains. and pin 8 of IC1. It should be close to 5V. Similarly, the voltage across C1 should be close to 8.4V. If these checks are not correct, disconnect the supply and recheck all the components and orientation. If everything is OK, place IC1 in the circuit and connect the power cord as shown in the wiring diagram of Fig.2. The two cords must be secured to the case using appropriately-sized cord­grip grommets. Note that the mains earth wires must be twisted together and secured using BOTH screws in the BP connector. The PC board assembly can be attached to the lid of the case using contact cement or other adhesive, after which the lid can be fastened to the case. Now connect a table lamp and plug in to the 240VAC mains. The lamp should initially be off and you should be able to turn it on by waving your Resistors 1 3.9MΩ 0.5W 1 2kΩ 1 470Ω 1 100Ω 1W 1 56Ω 1W WHERE TO BUY PARTS The design copyright for the Prox­ imity Detector is owned by Futurlec who can supply the PC boards plus all on-board parts (but not the case). The price is $19 plus $3 packing and postage within Australia. Orders may be placed via their website at www.futurlec.com using Bankcard, Visa Card or Master­card. Alternatively, orders can be sent with a credit card authorisation, cheque or money order to Futurlec, 24 William St, Paterson, NSW 2421. hand over the plastic case. To turn it off, just wave your hand over the box again or tap the case briefly. The unit could be used with other small appliances, such as radios or small TV sets and is ideal for the elderly or disabled who may have trouble SC with small switches or knobs. August 2000  65 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON $ 95* 10 CHIP’S Electronics TestBench inc GST ISBN 0 958522 9 2 8 A selection of from the page the best test equipment s of SILICON C www.silic HIP magazine onchip.c . om.au Structured Ca ...and the KRONE These days, it’s an unusual business that doesn’t have its computers networked. But there are networks – and networks. How can today’s organisation install a network that not only gives the performance required but also the flexibility to cope with change, growth, and emerging technologies? The answer lies in structured cabling. F irst, though, a network story that would almost make you cry. I can guarantee the veracity because I was there. Recently, a large firm of architects decided to move offices. They had occupied a whole floor of a city building with perhaps sixty or so computers networked via Cat5 cable (see “What is Cat5” panel). I was offered some of the office furniture that was surplus to requirements so went in one Saturday morning to get what I wanted. Ahead of me was an electrician, removing not just all the electrical wiring but all of the network and telephone cabling. The way he was doing this was simple: cut it off into small lengths and reef it out! We started talking about this incredible waste but he wasn’t too perturbed. The opposite, in fact: he said “hey, when the new tenants move in they’ll call me to put all this stuff back in again. I win both ways!” To make matters worse, he told me that this was by far his major source of income. “I do it all the time as companies move offices,” he said. “Sometimes they’re not even moving but reorganising, moving people around internally. You’d be amazed at how much stuff they put in, then pull it all out six months later!” 70  Silicon Chip While I would hate to see a sparkie done out of a job, all this wastage (to me) borders on the criminal. And the pity of it all is that it could all be avoided with a structured cabling system. Most new buildings are being cabled this way but it’s just as viable for existing buildings, especially when the occupants want to upgrade. Done once, it doesn’t need to be done again. What is a structured cabling system? Put as simply as possible, it’s a method of installing data and communications cabling which allows total flexibility by remaining fixed in place. Huh? OK, we acknowledge that’s a bit of a difficult concept to follow. How can a cabling system that is fixed in place allow total flexibility? Let’s take a typical scenario in a large company. Jane Smith has earned her promotion and moves into the manager’s office. Good news for Jane but now she has a different office, a different phone and possibly fax number. She plugs her computer into the wall socket and finds… nothing. Her by ROSS TESTER computer cannot talk to the network because the socket isn’t wired. Now the network administrator has to make a whole lot of changes, all Jane’s workmates have to change their telephone lists, the receptionist needs to remember the change . . . It’s all pretty simple stuff of course but it’s all very disruptive and costly. And don’t forget John Smith who has moved into Jane Smith’s old office, with a new telephone and fax number. At least his computer will talk to the network because Jane’s used to plug in there! Or another example: many organisations today use workgroups to tackle particular tasks or contracts. When that task or contract is complete, the members of that workgroup are disbursed to different workgroups to take on new tasks. Again, locations change, phone numbers change, computers move. It’s the above situation all over again but multiplied by the number of people involved. Wouldn’t it be nice if Jane and John Smith’s phone and fax numbers and computers (ditto everyone in the workgroup) could stay the same regardless of where they were physically located in the organisation? In other words, their “electronic” address(es) stayed exactly the same, abling Systems E “MiniLAN” Making changes to the phone, fax, network or other communication lines is so simple it’s almost child’s play. This particular version of the KRONE MiniLAN uses punch-down connectors but it could be just as easily loaded with plug’n’play couplers. regardless of their physical location. socket(s) close by, just waiting to be one point, a “switchboard”, of sorts, where the signal paths can be directed They can – with a structured ca- plugged in. and changed virtually at will. It is bling system. That’s at the worker’s end. But this ability to change which gives the Part of the secret is that when the the major feature of the structured network (or PABX system) is installed, cabling system is at the other end of system its flexibility. those cables. They all go back to the In fact, the word “switchboard” is every office, every possible location quite a good analogy. where a worker will be For those old enough located (eg, a desk or a to remember manual workstation) is pre-wired • Any service – telephone (voice), fax, data and even audio tele­p hone exchanges – just in case it will ever and video can be made available to any outlet as required. (Silvester switchboards) be used. where subscribers were Now if this seems like a •  Changing those services or re-routing to another outlet can connected by a switchbig waste of cable, in the be achieved within minutes. girl (sorry to be sexist but overall scheme of things •  The heart of a structured cabling system is the ability to they were almost always adding a few tens or even interconnect or “patch” cables together as required. girls!) who plugged lines hundreds of metres of •  Data rates of 100 megabits per second and more can be into appropriate cables cable in the installation achieved now – and as technology pushes speeds higher, on the board, that’s exphase costs a whole lot structured cabling can handle it actly what happens with less than trying to fix a structured cabling things up later – and then •  Old and new systems (or protocols) can be handled with system. paying for the disruption! ease. This means that an organisation does not need to When someone moves Every office, every desk update a complete system but can do it gradually. offices, all the network location has its own Structured Cabling in Summary: August 2000  71 TO ANOTHER NETWORK OTHER SERVICES IN (DIGITAL OR ANALOG) PHONE, FAX LINES IN administrator needs to do is swap the patch lead from its current location (the socket connected to the cable which went to Jane Smith’s old office) to the socket which connects to her new location. Exactly the same thing applies to her phone and fax lines: simply swap a couple of patch leads. The same simple solution applies with John Smith. He is “patched” through to his new location. No change of addresses or numbers, no problems – Jane and John Smith have moved but their business lifelines have moved with them – with little or no disruption. 72  Silicon Chip It looks just like a typical network – except for that box in the middle. It’s the heart of a structured cabling system and allows changes to be made virtually at will without re-wiring. The system is not limited to work-stations; it can also be used for shared equipment. A lot of equipment – printers, scanners, etc – is now appearing with network identification codes, making these devices “intelligent” as far as a network is concerned. They don’t even need to be connected to a PC – just plugged straight into the network. Believe it or not, there are even such things as intelligent video cameras which have their own ID – you can log on to these (eg, for security applications) as you would any other device with a network ID. These intelligent devices are called “network appliances” (that’s one of the new industry buzz-words you’re going to hear a lot more of!). You’re probably thinking that what we’ve been describing so far is for large organisations, Government departments and the like. But now structured cabling systems are also eminently suitable for SMEs (small to medium enterprises). With the right equipment, a structured cabling system is an elegant, cost-effective solution for the data and communications needs of any sized business – even the small office/home office (SOHO). Don’t you just love all these acronyms? Closed (left) and open (above) views of the KRONE MiniLAN before any cabling. This one has two 24-way patch panels (OK, one is a 23way because it’s missing a coupler!) as well as a modem on the shelf. As you can see, there’s plenty of space for more devices including another patch panel if you wish. It’s all up to you and your needs. The KRONE MiniLAN The KRONE MiniLAN, distributed by Namlea Data Systems (NDS), is an excellent example of the “heart” of a structured cabling system. Where large companies, government departments and so on might require a room-sized installation, the MiniLAN is the solution for small businesses. That’s not to say those larger organisations don’t have applications for the MiniLAN: remember those workgroups we talked about before? The MiniLAN is the perfect method for connecting a workgroup back into a large organisation’s mainframe. Perhaps even more importantly, it allows a mixture of protocols on the same network (protocols describe the way computers talk to each other over the network). A MiniLAN can provide the gateway for a network operating on one protocol to talk to another (perhaps larger, older) network. And as we said above, it also allows such things as printers, scanners and other network equipment to be placed Two types of RJ-45 jack, showing the difference: on the left is a “coupler” which is in fact two back-to-back jacks. These are used only with patch cords. On the right are two “punch-down” jacks (front and rear) which require connection with a special punchdown tool to solid core Cat5 LAN cable. wherever convenient – exactly the type of flexibility large organisations have been demanding. The point is that the MiniLAN and structured cabling make perfect partners for any organisation with changing requirements – whether those requirements are current work practices, future expansion – anything. The MiniLAN is small – just 301 (W) x 371 (H) x 102 (D)mm. Something this small can be mounted just about anywhere – anywhere that’s convenient to bring the cabling into. It’s suitable for wall or desk mounting. What makes the MiniLAN exciting though, is not its size nor its versatility. For the first time it is possible for anyone with a minimal knowledge of computer operation to change not only the network but telephone services as required. Until now, at least in the case of telephones, that’s been illegal. To change the position of a phone or a number in a business, you’ve had to call in an Austel-approved cabling installer who would make the necessary changes to your system and charge you accordingly. Because you’re not touching any of the wiring – it stays exactly where it was originally installed – you can quite legally make wholesale changes to the system. All you are doing is changing the positions of patch leads which make the connections to that wiring. As long as you can read the labels on the sockets and follow simple colour coding, you’re in business! Now you can see what makes MiniLAN such a boon for business. As well as avoiding the disruption of the person moving, you’re also avoiding the disruption of moving everything associated with the person. MiniLAN makes it that easy. You may have noticed that we have been freely mixing up computer networking and telephone circuits in this discussion. That’s deliberate – because MiniLAN can handle both at the same time. It can also handle audio, low-resolution video and more. Inside the MiniLAN The MiniLAN is designed to hold one, two or three 24-port patch panels (it is supplied with one of these patch panels fitted). There is also a shelf designed to accommodate all of the data/communications interconnectivity equipment required – a modem (or perhaps two), network hubs or August 2000  73 What is “Cat5”? As you may have realised, Cat5 is shorthand for Category 5. But what is this category and are there other categories? The cable categories you will find in general use are Cat3, Cat4 and Cat5. There are others, of course, but they won’t concern us here. These are all types – categories – of unshielded twisted pair (UTP) cables. As that name suggests, the pairs of insulated conductors within a cable are twisted together. Cat5 UTP has eight insulated conductors, twisted tightly together in four pairs. By the way, the pairs of insulated conductors or indeed the whole cable can also be shielded – known as STP, or shielded twisted pairs. STP is not as commonly used in Australia. You have probably seen and used Category 3 cable many times. Standard 4-core telephone cable is Cat3. As data cable, its use is limited to “low speed” 10-BaseT networks of 10 megabits per second or less. It is quite rare to find Cat3 cable used in data installations these days – but it is occasionally used. Cat4 cable is only marginally better than Cat3 – it is suitable for up to 16 megabits per second. It was originally used in Token Ring networks. Cat5 cable takes a massive leap forward in speed – up to 100 megabits per second and more. And now there is a new “enhanced” version – Cat5E , the so-called “Gigabit Ethernet” which is rated at 1000 megabits per second (1GB). Cat5E is only slightly more expensive than standard Cat5 so for new installations, looking towards the future, it is by far the better proposition. Here when we refer to Cat5 it could be either Cat5 or Cat5E. The MiniLAN, by the way, performs to Cat5E specifications. The outer insulation of Cat5 cables is almost always light blue. There are two types of Cat5 cable – one has a solid core and is intended for permanent installation (ie, in the wall or in ducts); the other has multiple conductors and is intended for patch cables. The first type is referred to in the trade as LAN cable, the second as patch cable. It is important not to use one in place of the other not just because of flexibility but also because of the connectors used. Cat5 is almost never soldered to – connectors are virtually always a crimped type. In the RJ-45 wall jacks or sockets an IDC (insulation displacement connection) is used, where the connection is made to each of the solid-core wires by tiny blades which pierce the wire’s insulation and grip the outsides of the wire. This is also known as “punched down” – the special tool to perform this action and terminate the wires is called a punch-down tool. Conversely, most RJ-45 plugs are designed to connect mainly to patch leads. In this case, a sharp point pierces the insulation and separates the multi-strands inside, making contact with many of them. This highlights one of the most-often-made mistakes with Cat5: using the wrong type of plug with the wrong type of cable. This problem is overcome by using ready-made leads (in fact, with telephone services, Austel rules require you to use approved (therefore pre-made) cables. Cat5 has a standardised colour scheme where the pairs of cables within the outer sheath can be easily identified. There are four basic colours – blue, orange, green and brown. The other cable of each pair has the same main colour along with a white stripe, or is white with the main colour as a stripe. Pair one, therefore, is blue and white/blue; pair two is orange and white/orange; pair three is green and white/green and pair four is brown and white/brown. Each of the pairs is assigned to a particular pair of pins on the modular connector so as to miminimse the chance of interference between the various transmit/receive pairs. There is one main standard used in Australia, 568A. This has pair one connected to pins four and five, pair two to pins three and six, pair three to pins one and two and pair four to pins seven and eight. Finally, there are limits on the lengths you can run Cat5 cable – the usual rule is 90 metres of LAN cable and up to ten metres of patch cable at each end – a total of 100 metres overall. If you think 100 metres is a long distance, you might be surprised just how much is used when running cable, especially when run around offices, up (or down) partitions and so on. Some brands of Cat5 LAN cable have their length back to the start of the roll printed on them every metre – that’s handy when you’re installing long lengths and want to know how much cable you have left! Wiring of Cat5 to an RJ-45 jack or plug following the Type 568A standard, the one most usually found in Australia. 74  Silicon Chip routers, internet gateways and so on. Each of the patch panels can be loaded with as many keystone inline jacks as required (up to the 24 maximum). The RJ-45 jacks (also called modular connectors) themselves can be either the traditional “punchdown” variety which has one side pre-wired and permanently connected (in the case of phone lines, by a licensed Austel installer) or can be double-ended which means both sides have RJ-45 jacks and use patch leads to connect on both sides (more correctly called “couplers”). What you use depends to a large degree on where you site the MiniLAN. Ideally, it should be close to where your phone lines come in, then patch leads and couplers can be used. If some distance away, your phone lines will need to be extended (by a licenced installer) and terminated to RJ-45 sockets. The major point is that once the phone lines are terminated to the back of the MiniLAN you don’t need to go there again. Everything is now done from the front. To use an oft-misused term, the MiniLAN is plug’n’play – you plug in, then play (or work!) Colour-coded jacks are available which tell at a glance what service is what. You can get red, blue, white, black, green, yellow and grey. What are all the colours used for? Well, Cat5 cabling is not limited to phone, fax or data. You can also run audio over Cat5 and even low-resolution video (eg, from the CCD cameras now available). Other reasons to use different colours are to divide the area into workgroups or sections (eg, marketing has black, warehouse yellow, and so on). The back of the MiniLAN is open, allowing completely unfettered entry of all cables. The front is protected by a hinged perspex door with just enough “smokiness” to camouflage (but not hide) what’s inside. It’s quite an attractive package. Installation Your first step is to decide how big a system you will be installing and for what purpose. Remembering what we said before about the future, it’s better to go too big than too little. Think of how much you’d like your business to grow in future – then add another 50% margin just in case you’re really successful! A typical Krone MiniLAN setup with the patch panel at top patched through to a 8-port network hub, thence to an internet gateway (bottom) and then a 56k modem, giving a full shared internet connection to multiple users. “RJ” jacks and plugs The industry refers to the modular plug and jack system as “RJ” . While possibly a misnomer (RJ more correctly refers to a cable standard), that’s what they’re commonly known as so   that’s what we’ll call them. The jack is the wall-mounted or floor-mounted socket, or   female connection, one of which is pictured above. The plug is the male connector which inserts into the jack (as pictured below). The 4-pin modular plug most commonly associated with telephones is known as a 4P4C, or four position four contact (even though in telephones only two are required and often only two are connected, which could be described as 4P2C). The RJ-11 and RJ-12 connectors are 6-position sockets used for voice applications. They're commonly used on answering machines. 6P2C sockets have two contacts wired (usually the middle pair), 6P4C have four contacts wired while 6P6C have all six contacts wired. The RJ45 connector is actually an eight-position socket. It is almost always loaded with all eight contacts wired (8P8C) but for specific uses can be wired with two contacts (8P2C), four contacts (8P4C), or six contacts (8P6C). RJ-11 and RJ-12 plugs can usually be inserted into an RJ45 jack but there is some danger of distorting the socket (due to insufficient sideways support). This may result in an unreliable connection. Incidentally, Telstra has recently announced             that they plan on standardising on an RJ45              socket for all new telephone installations. August 2000  75 The two different Cat5 cables in use and the two types of wall outlets: here we have LAN Cat5 wired through ducting to a pair of surface-mount boxes containing RJ-45 jacks (left) while the photo at right shows a surface-mounted double RJ-45 jack with a PATCH Cat5 cable going off to its device. You also need to decide which services will be connected through your MiniLAN and how you’re going to identify them. Take phone lines, for example: most businesses use a PABX or at least a Commander-type system. There’s nothing at all to stop you wiring these lines via the MiniLAN, just as there is nothing to stop you wiring direct or dedicated lines (fax/modem lines, for example). Note that installation of the lines from the street or from your PABX/ Commander system to the MiniLAN must be done by an Austel-licensed installer. But once they’re in place, you can route them as you wish. You would normally use one panel (or perhaps one area of a panel in a small installation) for your incoming services and another panel (or area) for your LAN connections, phone lines, etc. By the way, you aren’t limited to data and phone connections – the same cabling can be used for building security, audio distribution and even low-res video. However, there are limitations in using the cabling for a number of services due to interference between adjacent pairs of wires within the cable (crosstalk arguably being the worst problem). There are various ways in which these problems can be minimised – for example the amount of individual wire untwisted from the Cat5 cable must be carefully controlled. You may be wondering, as we did, if you want to run different services over the various pairs of conductors within the Cat5 – how do you do it? The answer here is to use a splitter – it doubles the capacity by separating out the cables into two RJ-45 sockets. You could therefore run two phone lines – one voice, one data; two data; or two voice over the same cable. 76  Silicon Chip Having said that, though, if you want to ensure top performance it is better to install additional Cat5 cables (at time of original installation) to run other services, especially if you’re going for high-speed or organisation-critical data. Running Cat5 I’ve installed a fair bit of cabling over the years – everything from unforgiving heavy-duty coax for amateur antennas to burglar alarm sensor wiring in impossible-to-reach places and even run kilometres of figure-8 up and down beaches for PA systems. But I have to say that Cat5 has to be the most ornery (cable) critter I’ve ever come across. I’m sure that Cat5 is what Murphy’s Law (or more specifically, his first cable corollary) was written for: the more impossible it is for a cable to tangle, the more certain it is that the cable will develop a tangle of monumental proportions; or the less likely a cable can possibly get caught on a snag, the more likely it will! Having said that, installing Cat5 cable is not dissimilar to installing any other type of cable. However, you should keep in mind that the wires in Cat5 for permanent installation in the wall or ducts (called Cat5 LAN) always have single solid conductors so it doesn’t take too kindly to kinking, stretching or jerking. Nor should you install it where it can be stepped on or chafed on tight corners nor curved too tightly in radius, which can degrade performance. If you have to pull Cat5 too hard (eg, to get it through a wall cavity) the holes it’s going through are probably too small. On a long distance run, if you have the choice (ie access), make the pull in two halves: pull it part way, then pull it through the rest of the way. Cat5 cables for patching have multi-wire conductors for flexibility because they are designed to be moved around. Having said that, though, they should still be treated with due care! You can choose a variety of mounting methods and locations for the wall or outlet jacks (sockets) for your Cat5 LAN. Standalone surface mount boxes are available for areas away from the wall. On walls you can use either those boxes or, for a neater appearance, jacks are available which will snap into standard Clipsal/HPM style wall plates (the same as those used for light switches) in one, two, three or four jack-to-the-plate configurations. Terminating Cat5 to modular sockets will usually require the use of a special cable stripper to remove the other insulation (or sheath) without damaging the inside cables. Then you’ll almost certainly need a punchdown tool to anchor the individual conductors correctly into the back of the socket, This is not difficult to do but before you try it for real, practise on some Cat5 offcuts! You can make Cat5 patch leads yourself – but why bother? They’re readily available in a wide variety of lengths and colours – and if the length of lead you want isn’t available “off the shelf”, companies such as NDS can make them to order. By the way, if you’re considering a MiniLAN or any other LAN installation, it’s well worth getting hold of a copy of the NDS catalog – it has a great deal of network information as well as all the products you’re going to need. Call (02) 9429 0800 and they’ll send SC you a copy, free of charge. Acknowledgement: Much of the information and some of the photographs and illustrations are courtesy of Namlea Data Systems. RemoteEye Caught in the Act ! RemoteEye is a digital remote security camera designed to provide dial-in remote access surveillance. RemoteEye combines stand alone event-triggered image capture with remote accessible interactive real-time viewing. By interfacing to standard alarm systems, security switches, or using it’s own built-in motion detection system, RemoteEye can record events as they occur. Dial up RemoteEye with your home or office PC, or on the road with a laptop, and it is a real-time surveillance camera. You can even have RemoteEye page you when a triggered picture is snapped or your alarm goes off ! Complete turnkey Solution: Ready to go, right out of the box, RemoteEye comes with a lens, 25ft cable, modem, power supply and RemoteEye software. The RemoteEye camera can be placed anywhere there’s a phone line and accessed remotely via modem (no PC required at camera site). Pager Notification: RemoteEye will automatically notify you whenever there’s something to see, using your numeric pager or cellular phone. division of Yager Electronics Pty. Ltd. - ABN: 19 060 819 516 * Sharp CCD 1/3” * Focal Length 8mm * Type: CS/Mount * Variable Aperture * AC adaptor 18V AC only $1995.00 E.A.O.E. Shop 501Capital Centre 255 Pitt Street, SYDNEY NSW 2000 PO BOX Q43, SYDNEY NSW 1230 Ph: 02 9264 0717 Fax: 02 9264 0817 email: yager<at>mpx.com.au www.optionalpower.com.au Mailorders - Cheques, Visa, Mastercard, Bankcard, Amex, Diners accepted. C.O.D. arranged. August 2000  77 CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. Soldering iron time-out Have you ever left your soldering iron on for days, having forgotten to turn it off when you last used it? This wastes power and it not good for the soldering iron tip either. This circuit will turn your soldering iron off if it is left in the stand for more than 12 minutes and uses Split supply with low quiescent current While it is relatively easy to use a power op amp to pro­vide a split supply from a 12V battery, most circuits have a quiescent current of 20mA or more. This circuit uses two op amps and two Darlington transistors and cuts the quiescent current to just a few milliamps. 78  Silicon Chip an infrared beam to sense when the iron is present. Infrared LED1 is the light source and this is sensed by infrared photo­ diode D1. When the beam is cut, the voltage at pin 3 of IC1a goes high and this causes the internal open-collector transistor at pin 1 to turn off, allowing the 220µF capacitor to charge via the 1MΩ resistor. When the voltage at pin 6 ultimate- Each op amp in conjunction with its corresponding Darling­ton transistor acts like a high power voltage follower. Assuming a 12V supply, pin 5 of IC1b is biased to +.029V while pin 3 of IC1a is biased to -0.029V, with respect to the 0V split. This means that only one Darlington transistor can conduct at any time and gives a small “dead band”. ly rises above that set at pin 5 by the voltage divider, the output at pin 7 goes low to turn off transistor Q1 and the relay and this turns off the soldering iron. LED1 and D1 should be mounted in tubes on either side of the soldering iron stand so that the beam is broken when the iron is present. Tom Hughes, Rangiora, NZ ($40) Despite this, the output voltage of 0V will vary by a negligible amount, even with fast switching loads. IC1 can be any frequency compensated dual op amp, such as LM­833, LM4558, LM358, etc. The Darlington transistor pairs can be BD­679/680, TIP142/147 etc. Manfred Schmidt, Edgewater, WA. ($35) Off-hook indicator has better visibility The Off-Hook Indicator for Tele­ phones published in the January 2000 issue has been quite popular but one drawback is that it has a narrow viewing angle due to the use of a highbright­ness LED. This version of the circuit overcomes that problem. The LM3909 LED flasher circuit has been modified to drive up to four LEDs. Depending on how these are mounted; eg, at different angles or on different sides of the box, it can produce a very wide viewing angle and thus good visibility. Briefly, the changes to the LM3909 circuit involve bigger capacitors, driving the four LEDs separately via individual 39Ω current limiting resistors and the addition of a further two resistors. The extra components will need to “hang off” the existing PC board or you could wire up the whole circuit on a piece of Veroboard. The modified circuit consumes about 2mA when flashing the lamps at 1.3Hz. The original circuit consumed about 0.3mA (flash­ing at about 1.1Hz). With this circuit it is able to run for about an hour. A rechargeable D cell could increase this back to the original seven hours but this would require the 220kΩ resis­tor to be reduced to 100kΩ to give an increased charging current of 0.4mA. Michael Ong Yong Kin, City Beach, WA. ($35) Silicon Chip Binders $12.95 Mains power for battery-operated clock While most clocks these days are crystal-controlled and powered from a single 1.5V cell, this circuit provides for mains-power so that the cell can be dispensed with if you want. On the other hand, if the cell is included, the clock will keep going if there is a blackout. As shown on the circuit, power WANTED! is derived from a 9VAC or 12VAC plugpack via diode D1 and the 220µF capacitor. This is regulated down to around 1.8V by LED1 and this is further reduced by Schottky diode D2. The third diode, D3, is included to insure that the battery is not charged by the DC supply. The LED flashes each time the clock ticks. C. D. Vickers, Elizabeth Downs, SA. ($20) PLUS $ 5 P&P AUST. ONLY Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. YOUR CIRCUITS AND PROJECTS! If you have a scathingly brilliant, original circuit that you’d like to share with the world – and make some money as well – send it in to us. We’ll pay up to $100 for a really good idea but there are a few conditions: • It must be your own work • It must not have been published or submitted elsewhere • It must be something other SILICON CHIP readers would find interesting. Send to: The Publisher, SILICON CHIP, PO Box 139, Collaroy, NSW 2097. email: silchip<at>siliconchip.com.au Phone: (02) 9979 5644 August 2000  79 PRODUCT SHOWCASE Weighty MCSE tomes from DSE Heavy in both senses of the word – content as well as mass – are these three Microsoft Certified Systems Engineer (MCSE) certification textbooks available through Dick Smith Electronics stores. The MCSE is a globally-recognised examination and certification system in which the candidate has demonstrated proficiency in a variety of Microsoft’s software and firm-ware. Such qualifications are often a pre-requisite to employment in the technical computer areas and successful candidates are much sought-after. Candidates must pass four required and two elective exams to attain MCSE status. While the books are not written by Microsoft they are certified as “approved study guides” by the juggernaut. The three books on offer from DSE are the Cat B-7300 720-page Windows NT Workstation 4.0 study guide (leading to exam 70-73), the Cat B-7302 550-page Networking Essentials study guide (exam 70-58) and the Cat B-7301 700-page Windows NT Server 4.0 study guide (exam 70-67). Each of the titles also includes a 4-decade RF probe CD-ROM containing over 1000 sample exam questions, interactive exams and even the option of studying the entire book on screen using your web browser. The books are all priced at $79.95 (pre-GST) which is very good value for money – and not just for the content. When you take into account the US price of $49.99 – on exchange rates alone, without freight or other import costs, this should make the price in Australia well over $85.00. Contact: Dick Smith Electronics (all stores) Website: www.dse.com.au For more information on the MCSE, visit www.microsoft.com/train_cert/ Aptly-named RF Probes Pty Ltd have introduced a passive RF probe, the RFP 5401A, for the measurement of in-circuit RF voltages. It has a sensitivity of 10mV and a frequency response of 100kHz to 750MHz (or to 1GHz or more with reduced sensitivity). Linearity is 500mV out for 500mV in <at> 1MHz (typical) while the maximum input permissible is 70V RMS (100V pk). With a fine, high tensile steel probe tip the RFP5401A is suitable for probing surface mount components or fine PC board tracks and pads with no blunting after repeated applications. It has a ground lead (mandatory for high frequencies) and output leads with standard banana plugs for direct connection to any standard digital multimeter on a DC volts range (with an input impedance of 10MΩ or greater). Contact: RF Probes Pty Ltd PO Box 6, Greensborough Vic 3088 Phone: (03) 9432 1936 Fax: (03) 9444 7750 Email: sales<at>rfprobes.com.au Website: www.rfprobes.com.au Oops! “When there's a bargain, word soon gets around…” We said that back in the July issue of SILICON CHIP, where we featured the $50 home satellite TV system from Av-Comm. Their switchboard went into meltdown mode microseconds after the magazine went on sale. All 400 systems that Garry Cratt had managed to get hold of were sold out in just four days! Yes, 400! He left a message on his answering machine telling customers this – but was still receiving faxed orders at the rate of about 50 a day as this issue went to press. We realise, of course, that means there are many disappointed readers – we all dramatically underestimated the incredible demand the article would produce. 80  Silicon Chip While there are no more $50 systems left, to try to keep faith with readers Garry searched hard and found some much newer, recently decomissioned analog systems. The price is a lot higher – $250 each inc GST, plus p&p – but this gets you a much more modern analog receiver (as pictured) in as-new condition and a brand new 85cm offset dish. The receiver, by the way, offers stereo audio, RF output as well as video/audio and has a remote control. You’d have to agree that’s pretty good value for money – not quite as good as $50, but good nevertheless! Once again, stocks are quite limited so if you missed out last time, you know what to do. Run, don’t walk to your fax machine or computer and order your system(s) – fax number is (02) 9939 4376 or email (cgarry <at>avcomm.com.au). No phone orders will be accepted – they’re too busy sending out satellite systems to talk on the phone! Of course, you can also order by snail mail (Av-Comm Pty Ltd, PO Box 225, Balgowlah NSW 2093). Good luck! New range of pro video batteries, chargers Premier Batteries has released a range of “NPI” high performance batteries intended to replace the manufacturer’s cells in professional broadcast cameras and similar demanding equipment – at a much lower cost than the original. Higher levels of performance are also achieved. The packs are 12V or 13.2V and range in capacity from 1.8Ah in Nickel Cadmium to 3.8Ah in Nickel Metal Hydride. Extended running times are achieved using packs fitted with the latest high-capacity cells. For safety and performance, all high capacity packs are fitted with excess temperature or current protection. The NPI Professional range are compatible with the range of video application chargers – System 90, IQfive and 10 Charger/Ananlysers. Premier Batteries offer a broad range of replacement batteries and cells to suit a huge variety of equipment. Contact: Premier Batteries Unit 19, 15 Childs Rd, Chipping Norton NSW 2170. Phone: (02) 9755 1845 Fax: (02) 9755 1354 Email: premierbat<at>one.net.au website: www.livenet.com.au/premier Mini worker works – cheaply! Most hobbyists and workshops have a reasonable selection of power tools. But there are times when the power drill or angle grinder simply isn’t appropriate – either because their use would be overkill or just because small size matters. Drilling PC boards is one example which springs to mind. This tiny tool from Jaycar could be exactly the right tool for a wide variety of small jobs – drilling, shaping, smoothing, grinding – and more. It’s just the right shape and weight to hold in one hand, gripped like an oversize pen. Its powerful motor spins at around 14,000 rpm from a 12-18V DC supply (nominally 12V <at> 500mA). A 3.5mm socket is provided at the back end for power which could come from a car battery, a workshop or lab bench supply or even a plug-pack with TOROIDAL TRANSFORMERS FOR SILICON CHIP AMPLIFIERS 15W CLASS A AMPLIFIER 80VA for single channel monoblock 240:2x21V/1.9A 160VA for amplifier as published 240:2x21V/3.8A 160VA low flux design + flux band 240:2x21V/3.8A 160VA low flux design + flux band 240:2x42Vct/1.9A ULTRA LOW THD 100W AMPLIFIER 160VA for single channel monoblock 240:2x35V/2.25A + 2x50V/0.1A 300VA for dual channel amplifier 240:2x35V/4.5A + 2x50V/0.1A $35.45 $42.50 $65.90 $74.40 $50.70 $60.45 500W MONO AMPLIFIER, as published 800VA 240:2x57V/7A $134.50 All prices include WST. Freight extra. HARBUCH ELECTRONICS PTY LTD Ph 02 9476 5854 Fx 02 9476 3231 enough “grunt”. The supplied grinding bit is said to be ideal for rust cleaning, sharpening, mould making and other types of metal grinding. It is supplied with two collettype chucks which accommodate shafts to 2.5mm. The best part of all is the low price – just $14.95 inc GST. Contact: Jaycar Electronics (all stores) Phone: (02) 9743 5222 Fax: (02) 9743 2066 email: techstore<at>jaycar.com.au website: www.jaycar.com.au PropMan HF Propagation Forecaster Program on CD The newly updated Propman 2000 HF Propagation Resource Manager program from Rockwell Collins identifies and displays the best channels for an HF communications link to and from virtually any points on the globe. Operating in a graphical Windows environment (95/98/NT/2000), it dramatically improves communications quality and reliability and is ideal for any HF radio operation. Features include a real-time plot update to user-changed HF link parameters (simplifies complex HF propagation predictions), display of current frequency summaries and recommendations, the ability to track, analyse and store HF propagation for multiple user radio site pairs and the ability to link degradation warnings. The software, on CD-ROM, is available direct from Rockwell Collins in the US for $US99 (about $AU165 at press time). You can find out much more about PropMan 2000 and its features by visiting the PropMan website. Contact: Rockwell Collins PropMan Dept 120-130, 400 Collins Road NE, Cedar Rapids, Iowa 52498 USA. Phone: (0011) 319 295 5100 Fax: (0011) 319 295 4777 Email: collins<at>collins.rockwell.com Website: www.collins.rockwell. com/gs/products/ August 2000  81 Hitachi’s “next-generation” DVD ROM and RAM drives Hitachi claim their new DVD ROM and RAM drives, due for release this month, will revolutionise the way video and data is stored and could spell the end of tape for storage and video. The new GF-2000 DVD-RAM drive offers up to 9.4GB capacity and 22.16Mbps data transfer rate (2.77Mbytes/ sec). According to Hitachi, this drive can double as a data recorder and storage system, or as a video replay device, as well as having full backward compatibility with older generation RAM, ROM and CD drives. Of particular note is the new drive which can read either the standard 12cm DVD disks (same size as “normal” CDs) as well as the new mini 8cm video DVD disk recently announced by Maxell. Hitachi have also released a DVD ROM (read only) which has a read capability of up to 12 times (depending on format) and at forty times CD speed. It is also compatible with single and double layered DVD ROM media, DVD-R, CD-R, CD-RW and standard CD-ROM. PICO data logging EnviroMon, distributed by Emona Instruments, is an extremely versatile, expandable data logging and alarm system, ideal for real time monitoring of a wide range of parameters such as temperature, humidity, pressure and energy usage over large areas. Applications include food storage & preparation, medical sample storage, document archive/art storage, horticulture, climatic monitoring, computer rooms and energy management. The logger that can store up to 15,000 readings taken at intervals from one minute to four hours. It automatically displays the reading from each sensor in turn and sounds an internal alarm should a problem arise. Detailed or summary reports can be sent to a computer for long-term storage and graphical analysis. Back-up batteries continues recording for up to 24 hours if the mains power fails. An optional telephone auto dialler can be programmed with a list of emergency numbers that it will call when there is a problem. Each logger is supplied with EnviroMon for Windows software, which is used to configure the system, download data to a computer, store data and provide graphical analysis of data. Contact: Emona Instruments Phone: (02) 9519-3933 Fax: (02) 9550-1378 e-mail testinst<at>emona.com.au 82  Silicon Chip LE Contact: Hitachi Australia Ltd 13-15 Lyonpark Rd, North Ryde NSW 2113 Phone: (02) 9888 4100 Fax: (02) 9888 4188 Website: www.hitachi.com.au Mitsubishi’s “no tape” time-lapse video recorder Most time-lapse video recorders on the market are simply adaptations of conventional VCRs, with all their limitations. Not so the new Mitsubishi DX-TL900E: it’s all digital. Not just digital recording: no tapes! Some of the most advanced digital recording features have been incorporated into the new recorder. High resolution playback (over 400 horizontal lines) is possible thanks to the digital technology using JPEG compression. When close-ups of crucial areas of security are required (cash registers, for example) the recorder has an electronic zoom function. It also has a watermarking feature designed to safeguard images. The unit also incorporates a nine camera input multiplexer which can display all inputs in split screen for non-simultaneous throughput and camera feeds from 1, 4 or 9 cameras on split screen sequential playback. A 10GB hard disk is included for high reliability and high speed operation, with another three external hard drives as options giving a massive 106GB total recording medium. Different cameras can be programmed to record at various times of the day using the Timer Program Link, and the unit can perform backup and copy operation without interrupting recording. DDS, DVD-RAM or MO can be used as the backup media. Contact: Mitsubishi Electric Australia Phone: (02) 9684 7777 Fax: (02 9898 0484 Website: www.mitsubishi electric.com.au Tiny, high pressure 12V liquid pump Dick Smith Electronics have one of those items which many people have wanted over the years but have never known where to go to get one! It’s a high pressure, 12V DC pump which can be used for anything from water to thin oil. With a flow rate of three litres per minute and a head of around two metres, the pump is also ideal for garden water features and other d-i-y applications. The motor speed is 16,000 rpm and the pump draws about 2A at 12V DC. Data and application notes are supplied with each unit. They’re available at all Dick Smith Electronics stores and DSE PowerHouse stores and DSE Mail Order for $19.95 inc GST. ECTRONICSHOWCASELECT 3990 FULL RANGE $ ELECTROSTATIC Now you can afford the legendary clarity, transparency, depth and precision of an electrostatic speaker. The new Vass ELS-5 is a full range electrostatic speaker, able to faithfully reproduce frequencies from 40Hz-20kHz. • 5 Year Warranty • Wide range of custom finishes. • Individually hand built & tested. 1/42-44 Garden Bvde, Dingley 3172 Pyramid subwoofer Ph 03 9558 0970 Fax 03 9558 0082 separately available email: vass<at>hotkey.net.au Do you want YOUR product or service showcased to Australasia's most important electronics marketplace? CALL ME: RICK WINKLER on (02) 9979 5644 and let me explain how cost effective the SILICON CHIP ELECTRONICS SHOWCASE can be for YOU! EMC Technologies' internationally recognised Electromagnetic Compatibility (EMC) test facilities are fully accredited for emissions, immunity and safety standards. EMC Technologies Melbourne: (03) 9335 3333 Sydney: (02) 9899 4599 MicroZed Computers GENUINE STAMP PRODUCTS FROM Scott Edwards Electronics microEngineering Labs & others Easy to learn, easy to use, sophisticated CPU based controllers & peripherals. PO Box 634, ARMIDALE 2350 (296 Cook’s Rd) Ph (02) 6772 2777 – may time out to Mobile 0409 036 775 Fax (02) 6772 8987 http://www.microzed.com.au Most Credit Cards OK M croGram Computers August 2000  83 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG The Astor RQ – the Lady’s Handbag Radio Back in the days of valve radios, portable sets were a luxury item. They were expensive to buy in the first place and they were even more expensive to run. The Astor RQ set we look at this month was even more of a rarity in that it did not look like a radio. When visiting a friend of mine recently, he brought out a lady’s handbag which he said he was going to give to me. I thought, “He’s having me on, giving me a lady’s handbag. What’s he up to?” As you can see from one of the photographs it does indeed look rather like a lady’s handbag. When the bag was opened, an attractive compact Astor portable radio was revealed. Then I knew I wasn’t being conned. When you think about it, the set was probably meant to look like a lady’s handbag, with a stout brown leather case and a shoulder strap. As with all advertising there is an aim to entice various groups to purchase their wares, and so it is in the radio retailing business. This set, an Astor RQ, was produced in 1955 and probably up until that time the main emphasis had been on selling to the man of the house. The “Little Lady” got scant attention, particularly in the portable radio market, and probably for two reasons. Sets had been much too heavy for women to comfortably carry and the sales people hadn’t yet thought of women as having a mind of their own let alone an income of their own. Astor obviously woke up to that fact and produced this set that would have been quite attractive to the more independent young women of the day. It opened up a whole new market. How well Astor did with this model and similar sets I don’t know. They probably sold many thousands of sets that they wouldn’t have sold if Below: running the set from a battery eliminator is more practical than using batteries which don’t last long at all. 84  Silicon Chip Fig.1: the circuit of the Astor RQ is typical of many 4-valve sets of the era. Note the unusual method of obtaining grid bias for the 3S4 output valve, taken from the oscillator stage. they had stuck to the “tried and true” methods of sales pre­sentation. What’s in the handbag? Compromises have to be taken in some way or another when equipment is miniaturised. By today’s standards the set is large but in 1955 it was quite small, around about the same bulk as the Astor KQ which was produced back in 1947. Several compromises were made to ensure that a small set of reasonable performance could be achieved. Small sets of this calibre rarely had an RF stage which limited their performance in country areas. However, there was a saving of LT and HT current. Because these “personal” portables were small, rather inadequate inbuilt loop aerials had to be used. However, in this set, an 8" x 3/8" ferrite rod aerial/antenna was installed, which was virtually an industry standard for broadcast band loopstick aerials from the mid 50s onwards, and hence the signal pick up is quite reasonable. Batteries were a real problem. They were heavy if they were to have reasonable life in the set, expensive and bulky. However, in this set and in much later sets, the smallest batteries available were used, with limited operational life. In this set, they opted to use two D cells to supply the 250mA of filament current and a 467 67.5V battery to supply the 10mA of HT current. A battery life of 50 hours would probably be all that could have been expected. Much later an Australian-made Kriesler transistor portable set used a 286 battery which gave a claimed operational life of 1000 hours. That is some difference. Back bias Most of the later battery-powered radios used back bias to obtain the grid bias for the 3S4 or 3V4 output valve. This was done by putting a resistor between the negative terminal of the HT battery and the set chassis. The battery negative was taken via a resistor to the grid of the 3S4/3V4 and hence it had a bias of around -7V for a 3S4. The negative voltage was devel- oped due to the current drain across the battery negative to chassis resistor. This did away with the separate bias battery commonly used by sets that used the 2V series valves. There is one significant disadvantage of doing this, as the -7V bias is taken away from the 67.5V total HT voltage, which means in this case that only around +60V is available for opera­tion of the set. How could the circuit be arranged so that the full HT voltage was available and still not have to use a sepa­rate bias battery? Astor got around this nicely. They attached the 3S4 grid resistor to pin 4 of the 1R5 which is several volts negative due to the operation of the local oscillator; simple but effective. With only 67.5V HT available the maximum audio without noticeable distortion is around 180 milliwatts, and as the bat­ teries discharge this will decrease to below 100 milliwatts. Taking into account the state of the batteries and that the output transformer is around 66% efficient, an output varying between 60 and 120 milliwatts is available to the speaker. August 2000  85 will do the trick. So they can but they will end up costing quite a few dollars too. If you really want to use the set as a portable this is probably the only practical solution. A l t e r n a t i v e l y, y o u n e e d a mains-powered battery eliminator. Battery sets using 1.4V and 2V valves require up to 300mA at 1.4V or up to 1A at 2V and high tension voltages of 67.5V, 90V or 135V at less than 25mA. I built a suitable supply several years ago that will power dry battery radios and some that use wet cells too. I used this to power the set. (Editor’s note: If there is sufficient reader interest, SILICON CHIP could present a suitable circuit). Restoring the handbag radio No, it’s not a lady’s handbag but a nice little 4-valve portable radio. The speaker, a Rola 3C, is certainly not very efficient so overall there is not much chance of entertaining all the neighbours with the set going full bore. There is no disputing that sets of this nature are “personal” portables. What is the RQ like? An initial look at the back of the set indicated that it would be quite reasonable to dismantle and restore. Regrettably, on closer inspection a few problems become apparent. If valve re­placement is the only requirement for service, the 1R5 can be easily replaced. If the other valves require replacement a small screwdriver will be needed to lever the valves out as it isn’t possible to get fingers around the valve envelopes. More serious service work requires the set to come out of the cabinet. This is achieved by removing the hand-span tuning knob and the off/ on-volume knob, then the speed nuts on plastic spigots in the cabinet. My experience of undoing these is that the plastic spigots often break and compounding this, long needle nosed 86  Silicon Chip pliers are needed to turn the speed nuts. Even taken with great care the job can result in broken mounting spigots. Powering the set – how? The difficulty of powering a battery set has probably caused many collectors and restorers to bypass battery-powered sets. Assuming a suitable power supply is available, caution is needed to ensure that high voltage is not applied to the fila­ments by mistake or through a measuring probe slipping off a point being measured and shorting HT to the filament line. Should this happen all these low voltage and current filaments will be burnt out. Indirectly heated valves will stand a short term short circuit without damage. It isn’t hard to put a couple of D cells in to provide the LT supply but the HT supply is a different story. 467 type bat­teries are generally unobtainable and when they are, they are extremely expensive and their quality is often suspect. Some decide that a string of eight 216 9V batteries As mentioned earlier I had expected the set to be easily overhauled but it didn’t prove to be quite that easy. The back came off easily; too easily like many Astor sets with plastic cabinets. With time and heat, the plastic warps and the retaining clips no longer make good contact. In fact, the previous owner had used sticky tape to hold the cabinet together. The valves could be removed with a little bit of persist­ ence and each was tested with an ohmmeter to make sure that the filaments were still OK – they all were. Check what voltage and current your multimeter uses to do its measurements before checking battery valves. With the probes short­ ed, the current must be under 50mA or the valves filaments may be blown while being tested. To make the wiring and components more accessible for in­spection (and replacement if need be) the chassis had to come out. First of all the two knobs were pulled off. Then the speaker wires and an earth wire were removed from the speaker frame as I couldn’t remove the speed nuts from the speaker mounts without breaking the mounts. Next, an attempt was made to remove the three speed nuts securing the chassis to the cabinet. Two responded and could be twisted 90° with needle-nosed pliers and re­ moved. The third was a different kettle of fish. When the speed nut was put on it was just pressed on and locked in place but there was no room to twist it 90° as the tuning gang fouled it. So it was a matter of undoing the three ELECTRONIC VALVE & TUBE COMPANY It looks like this inside the case with the batteries installed. screws holding the tuning gang to the chassis and lifting it clear so that the speed nut could be turned and removed. The gang was then put back in place and the mounting screws reattach­ed, after which the chassis was withdrawn for inspection. I like to work with a circuit diagram as it makes things just that much easier. Alas, this time I didn’t have one. (As it happens, I did obtain one after I had finished restoring the set). What I did was to look and see if I had any other portable 4-valve Astor circuits. I fortunately came across the circuit of the KQ which mechanically is quite different and the design is nine years older – but would you believe it is virtually identi­cal? So the moral of the story is if you don’t have the circuit of the set you’re working on, look for a circuit by the same manufacturer with a similar valve lineup and doing a similar job. Even other manufacturers’ circuits for similar sets are better than nothing. This neat little set uses a 1R5 converter, 1T4 IF stage, 1S5 detector and first audio stage, and a 3S4 for the audio output. The paper capacitors weren’t particularly leaky but battery radios are not very tolerant of any leakage. The replacement polyester capacitors were roughly the same colour and size which means they didn’t look out of place. The resistors were all checked and a few were found to have gone high and out of toler­ance, so they were replaced too. The rubber wiring insulation had gone hard and cracked. I made sure I didn’t shift it otherwise I would have had to replace it all, not that there was a lot in such a simple set. Next to be checked was the speaker transformer. These are often a source of problems as they can go open-circuit in the primary. And sure enough, it was open-circuit. One problem: the replacement had to be smaller than usual as the one in the set was quite small. If it was too big the cabinet back would not fit on. Fortunately I had a suitable one. It is interesting to note that the speaker transformer frame is connected to the +67.5V HT rail. This was done in an attempt to overcome the problem of electrolysis caused by small currents between the primary and frame. Astor often did this with their battery sets. Didn’t work this time! Having done all these things and made sure everything visu­ally looked OK it was time to connect the dry battery power supply. First, I double-checked that the power supply was providing the correct voltages (1.4V and 67.5V) and all was well. It was a case of connecting the battery clips to the supply via small jumper clip leads. As the set was still out of the case at this stage, clip leads were also used The Electronic Valve & Tube Company (EVATCO) stocks a large range of valves for vintage radio, amateur radio, industrial and small transmitting use. Major current brands such as SOV-TEK and SVETLANA are always stocked and we can supply some rare NOS (New - Old stock) brands such as Mullard, Telefunken, RCA and Philips. Hard to get high-voltage electrolytic capacitors and valve sockets are also available together with a wide range of books covering valve specifications, design and/or modification of valve audio amplifiers. PO Box 487 Drysdale, Victoria 3222. Tel: (03) 5257 2297; Fax: (03) 5257 1773 Mob: 0417 143 167; email: evatco<at>mira.net New premises at: 76 Bluff Road, St Leonards, Vic 3223 P.C.B. Makers ! • • • • • • • • • If you need: P.C.B. High Speed Drill P.C.B. Guillotine P.C.B. Material – Negative or Positive acting Light Box – Single or Double Sided – Large or Small Etch Tank – Bubble or Circulating – Large or Small U.V. Sensitive film for Negatives Electronic Components and Equipment for TAFEs, Colleges and Schools FREE ADVICE ON ANY OF OUR PRODUCTS FROM DEDICATED PEOPLE WITH HANDS-ON EXPERIENCE Prompt and Economical Delivery KALEX 40 Wallis Ave E. Ivanhoe 3079 Ph (03) 9497 3422 FAX (03) 9499 2381 • ALL MAJOR CREDIT CARDS ACCEPTED August 2000  87 This photo shows the set with the batteries removed from the case. to connect the speaker to the receiver. Now for the moment of truth: the power was turned on – and I was greet­ed with silence. I put the multimeter probe on the grid of the 3S4 and was greeted with a click and a little bit of hum. So far so good, now try the 1S5 grid – nothing. I’d tested the filaments and found them all OK but that doesn’t mean the valve will work and this one didn’t. I have a small supply of battery valves so I rummaged around and found one. After replacing the valve (after turning the power off), I then touched the grid with the probe and got a healthy blurt out of the speaker – still no stations though. I put the signal generator output lead near the input to the first IF transformer and wound up the output while sweeping the gen­ erator around 455kHz. In a moment, the beautiful tone of the generator came through. So the IF was OK. I then tried forcing broadcast signals through the set by connecting the generator lead over the insulated lead coming from the loopstick aerial but no go. Perhaps the 1R5 converter was faulty. I put a fresh one in and the noise level out of the receiver came up and I could hear stations as I tuned 88  Silicon Chip across the band. It looked like I had overcome most of the set’s problems. The next thing was to go over the alignment. Some folk are reluctant to touch the alignment and if the set sounds reasonable it is left alone. I knew that the oscillator and aerial circuits were a bit out of alignment so the IF would probably be too. I fed a tone modulated signal on 455kHz from the generator into the aerial tuned circuit, at a level that produced a noisy signal through the speaker. I tweaked the four slugs in the IF trans­ formers for peak performance – they were only a little out of tune. It isn’t possible to do this unless the chassis is out of the cabinet. From there it was necessary to determine how far the align­ ment was out. The set is intended to tune from 535kHz to 1610kHz. The slug in the oscillator coil was adjusted so that 535kHz was received with the gang fully in mesh and the oscillator trimmer was adjusted so that 1610kHz was received with the gang fully open. This was done as the oscillator slug is difficult to access with the chassis in the cabinet. Having got the oscillator fre­quency range approximately correct, the chassis was then put back into the cabinet. Now the control knobs and the radio station scale were fitted. With the station scale in place it was possi­ble to get the stations on the correct places on the dial. Ad­justing the oscillator coil slug wasn’t easy but it required very little to get it correctly adjusted, and likewise the trimmer. The aerial/antenna circuit was easy to adjust. First, the small adjustable coil on the loopstick was slid along it for best performance at around 675kHz (2CO) and the aerial trimmer adjust­ed at around 1400kHz for best performance. As these do interact, you need to go over the adjustments until no improvement is observed. Always try to do this with relatively weak signals if you are doing it all by ear. Finally, seal the trimmers, oscillator core and the sliding antenna coil with a little beeswax or hobby glue to make sure the adjustments don’t shift with time. The IF adjustments were rea­sonably firm and shouldn’t shift. That was about it, other than giving the cabinet a cut and polish. Due to the warping, deep scratches and so forth that happen to plastic cabinets, they don’t come up to the high stan­dards of finish that we’ve come to expect with wooden or Bakelite cabinets. Summary The Astor RQ was a nice little set, not a tremendous per­former but typical of most 4-valve portables of the era. It filled a niche particularly for women who wished to listen to what they wanted, not dictated to by their husband or boyfriend. Battery life would not have been particularly good and the cost of batteries would have been high. As a simple set it was not as well thought out for service as it could have been. Battery radios form a small but important part of our radio history, so even if they are not your cup of tea some other collectors like them. As batteries are either expensive or unob­tainable, running the sets as true portables is not practical. Mains-operated battery eliminators are really the only practical way to power sets such as this. Many people have thrown out their battery valves as use­ less. They are much rarer than mains valves and due to their relative fragility don’t last as long, so don’t throw them out - give them to someone who restores battery SC radios. ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Regulated supply for LM3876 amplifier I am in the process of building the 50W amplifier module based on the LM3876, as published in the March 1994 issue. I intend to use this in my study and have the 15W class-A amplifier in the living room. I have read with interest about the 100W Ultra-LD amplifier in the March & May 2000 issues but I like the simplicity of the chip amplifier. Also, I do not need the power. My questions relate to the power supply for the 50W amplifi­er. I would like to use a regulated power supply. Do you have a circuit or can I modify the class-A amplifier power supply? I understand that regulated power supplies are better and would like to go down this path. Can you assist? (D. F., Sydney, NSW). • There are unlikely to be any benefits in using a regulated power supply with the LM3876. You will not get any better distor­tion because there is no way of separating the supply lines to the small signal stages from the output stage (ie, there is only one supply Speed alarm for 1971 VW I am writing to see if there is an alternative sensor to the one suggested in the Speed Alarm kit. I purchased this item and thought it would solve the speedometer inaccuracy problem in my 1971 VW beetle which has a speedometer in miles/hour. This kit appeared to have the features I required; ie, a display in km/h. My problem is that it requires a sensor mounted on the drive shaft but as you probably know the VW doesn’t have a normal drive shaft, only rear axles which have a diameter of 25-30 mm. I don’t think these axles rotate at the same speed as a drive shaft connection for each rail – pin 1 & 4). Second, even if you could separate the supply lines, the latent distortion in the LM3876 is about an order of magnitude worse than the Ultra-LD, at high frequencies and about three to four times worse at mid frequencies. You can compare our pub­lished distortion curves from the LM3886 (virtually the same as the LM3876) in the February 1995 issue with the curves for the Ultra-LD amplifier in the March and May 2000 issues. The point about using regulated supplies with a class AB amplifier is that it only gives quite small improvements. Unless the amplifier is inherently very good, there’s not likely to be a benefit. Apart from that, a regulated supply is quite a lot less efficient than an unregulated supply and you do not have the benefit of “headroom” whereby the amplifier delivers more power on transients than it does on steady-state signals. If you’re still keen to improve the power supply for the LM3876, the best way to do it is to double the size of the filter capacitors; eg, increase from and secondly, the diameter of the drive shaft only allows a small number of magnets which I feel may be unsatisfactory. Can you suggest an alternative sensor? (D. O., via email). • You can use a different speed sensor. The Jaycar photo interrupter (cat ZD-1901) could be used in conjunction with a rotating disk (driven by the speedo cable) which has slots to interrupt the optical beam. The circuit to connect the internal LED and phototransistor is simple and was used in the rain gauge as published in the June 2000 issue. It comprises a resistor in series with the LED and a resistor in the transistor collector. The collector signal could then be applied to the coil input for the Speed Alarm. 2200µF capacitors to 4700µF. Finally, if you are determined to persist with a regulated supply, you can upgrade the circuit for the class-A supply. Ultrasonic pest eliminator for ants I am currently having a problem with ants around the home, mainly in the ceiling. I have seen a unit on TV that claims to get rid of pests using what appears to be ultrasonics. Has SILICON CHIP ever run any articles or projects on the use of ultrasonics for the removal of pests. If so, could you tell me which volume the articles appeared in. (M. P., via email). • We have published a number of ultrasonic circuits to control the barking of dogs (most recently in July 1999) but as far as we know, ultrasonics have absolutely no effect on insects. In fact, one of the TV current affairs programs did a good job of debunk­ing ultrasonic cockroach repellers several years ago – it showed the cockroaches even crawling all over the piezoelectric tweet­ers. Replace points for high energy ignition A few years ago I built the original High Energy Ignition kit as published in the May 1988 issue of SILICON CHIP. Installed into a Mazda 323, the unit has performed flawlessly and I have not replaced the points since. Recently, I noticed that the “engine speed unit” (tacho?) in the car was not working and found that the dwell extension of the ignition kit was the culprit. Have you seen this before? If so, do you have a modification for the circuit? I noticed, on your website, that there are a few Notes & Errata on this kit but I don’t have copies of those issues. Can you help me at all? (D. W., via email). • We are bit concerned that you have not replaced the points in all this August 2000  89 Tacho doesn’t work on Land Rover I read with interest the article about the new Digital Tachometer in the April 2000 issue. I already have the digital tacho described in the August 1991 issue but I’m attracted by the new design because it is much smaller and easier to fit into a car’s dash. I originally fitted the older tacho to my Holden-powered Land Rover. The instrument performed faultlessly so long as I had a points-style distributor triggering a SILICON CHIP Transistor Assisted Ignition. I triggered it from the negative terminal of the coil and all was fine. Then I installed a Bosch reluctor distributor and coil as fitted to Holden motors for a couple of years in the early Com­modores. The tacho thereafter refused to register anything. I checked the tacho in another car; it worked fine. So far as I know, the Bosch “black box” is merely a potted circuit board containing a big switching transistor and the associated circuitry to drive it from the reluctor pickup. It is a black resin slab with two leads from the reluctor, one to ignition +ve and one to coil -ve. Whether it has the extended dwell feature of time. What you will find is that the rubbing block wears down until you have virtually no gap at all. Unless you have already done so, check the points gap and if necessary, replace the points. Trouble with modified class A amplifier I have designed my own version of the Class A amplifier with the power transistors and drivers plus power supply filtering on a separate board to the other parts. The boards are joined with pins. However, I am having a problem setting the quiescent cur­ rent. Every time power is supplied, the 1.8Ω 5W resistors develop about 10V across them and then cook. I have been over and over the design and cannot find any faults. I suppose it may be something in the actual layout, though that received much attention 90  Silicon Chip the TAI, I don’t know for sure but I think it might. I gave up as I did not have access to a suitable oscillo­scope to view the size and duration of the voltages around the operating ignition system. A comparison with the readings from a conventional points ignition might have told an interesting story. Do you have any idea why the tacho refused to work with the reluctor ignition? More to the point, do you think that the new digital tacho will work? Have you actually tested it with an older reluctor type ignition? (P. M., Mackay, Qld). • The older Digital Tachometer should work with reluctor style ignition systems since the pickup is from the coil primary as per the points system. Possibly dwell extension in the reluctor triggering may produce a signal which is too short for the tachometer circuit to operate successfully. You could try in­creasing the value of the .022µF capacitor at the base of Q1 and decreasing the .01µF capacitor value at the junction of the 33kΩ resistor and 10kΩ resistor to ground at the coil input. The Digital Tachometer described in April 2000 was tested with older style reluctor ignitions. during my design. (G. F., via email). • It sounds as though you have a problem with Q10, the quies­ cent current setting transistor. If it is open circuit or its base bias resistors are the wrong value etc, it can turn the output stage full on. To check, short the collector and emitter of Q10 with a short clip lead. The current through the 1.8Ω resis­tors should drop to zero. If not, you could have a short some­ where in the output stage. this matter? Also, I have an inductive pickup from my old timing light which I can use to get the input signal from the number one spark plug lead. Is this possible? Or can I modify the circuit to use the inductive pickup? As my car does not have an RPM meter, I always had problems adjusting the idle speed. Therefore my main purpose is to use this circuit as test equipment rather than as a permanent tachom­eter. (A. G. via email). • The inductive pickup may operate the digital tachometer when connected to the high voltage input. You can only try it. You also may be able to find the connection to the coil primary by checking the service manual for your car. Many vehi­cles do have a tacho signal output even though the car does not have a tachometer. Information on this can also be obtained from the service manual. Nickel metal hydride battery charger wanted I am thinking of modifying the battery charger you published in October 1998 to recharge some metal hydrides. I don’t know a lot about metal hydrides so I was wondering if you have done or are intending to do an article on this topic. (D. C., via email). • We would not recommend the October 1998 design for charging nickel metal hydride batteries. This design was intended for lead acid batteries. Nickel metal hydride (NiMH) batteries are very similar to NiCd types but without the memory effect. They require a charger which will sense the dV/dt change at the end of charge. We suggest that you have a look at our Multi-Purpose Fast Charger which we published in February & March 1998. 12V neon Mitsubishi has no pick- modulator kit up point for tacho I want to know a few things about I recently constructed the Digital Tachometer which was published in the August 1991 issue of SILICON C HIP . Unfortunately I could not connect it to my Mitsubishi Lancer because it has an internal ignition coil situated inside the distributor. Could you please give me some advice on the 12V neon modulator for use with subwoofers (May 1997). Firstly, I wanted to connect the unit using a guitar amplifier as the signal source. The blurb on the DSE website says that you hook it into the sub­woofer – does this mean that the kit only applies itself to certain signal ranges or it is only triggered by the ranges put out by the subwoofer amplifier? If you connect it straight into a signal source, would it flash for all frequency levels? Secondly, instead of using one 12V neon tube, would it be possible to connect eight 1.5V LEDs to the unit? Thirdly (and this is just to confirm), any 12V DC power supply should run it, right? (D. C., via email). • You really need to refer to the complete article to under­ stand the function of the circuit. We can supply the back issue for $7.70 including postage. As designed, the circuit will not respond to frequencies above 100Hz but by reducing the 0.1µF capacitor at the collector of Q1 you can improve this. However, the circuit and the neon tube itself inherently do not have a fast signal response - it’s really only intended for bass frequencies. You could connect a string of LEDs but you need a limiting resistor to set the current. By the way, most LEDs have a voltage drop across them of around 2V so you could only use about five, after allowing for the series limiting resistor. Yes, you can use any 12V supply. Mailbag – from page 25 said why? No wonder you give up after a while. I’m unable to recall how often on a new installation a 3-phase blower motor runs backwards; we all know that swapping two phases will make the motor rotate correctly but why is it sup­plied in the wrong rotation? I’ve no doubt there are excellent electricians out there, but I despise an organisation that allows the bad apples to remain and reject those who don’t do the apprenticeship but have Notes & Errata Simple Superhets, April 2000: the circuit on page 61 has an error. The grid of the 6GW8 triode should be pin 1, not pin 3. Ultra-LD 100W amplifier, March & May 2000: to eliminate a notice­ able thump from the speakers at switch-off, we recommend that the 100µF capacitor connected to the regulated -55V rail be increased to 220µF 63VW. Digital Voltmeter For Cars, February 2000: when using the volt­meter with 24V vehicles, the five 820Ω resistors will become quite hot. To alleviate this problem, we recommend replacing the 820Ω resistors with 10 1.8kΩ 1W resistors. Five can be installed on the PC board in place of the original 820Ω resistors. The other five can be installed underneath the PC board. Alternatively, use a 150Ω 10W wirewound resistor external to the voltmeter in place of the five 820Ω paralleled resistors which should be replaced with a short or link. The 10W resistor must be placed on the metal chassis of the vehicle using a suitable skills and at least a much better appreciation of AS3000. What really scares me nowadays is we are now letting these bad apples perform communications work and I’d be pretty sure that adherence to mandatory separations between mains and comms is frequently disregarded. I’m sure you all recall that GPOs used to be available with integral TV sockets until one day when an unsuspecting person was killed while attempting to rotate his aerial. These are illegal now and in effect was prior recog­ nition that some electricians cannot clamp and the connections insulated. The wiring should be clamped to the chassis to prevent breakage from the resistor leads. Low Distortion Audio Signal Generator, February & March 1999: the published PC board (01402992) shows a short between the 0.18µF capacitor on switch S2 and the adjacent shield track. This was due to a glitch in the conversion from the original Protel file to an HPGL file required for publishing. The overlay diagram on page 64 of the March issue shows the pattern correctly without the glitch connection. The Protel files sent to PC manufacturers were cor­rect. Also the 12kΩ resistor connecting between the LDR1 and VR3 should be replaced with a parallel combination of a 560kΩ resis­tor and .0047µF capacitor. Some constructors are using 3000mCd red LEDs for LED1 and LED2 with improved results. VR6 can be changed to 1kΩ to improve the ease of square wave output adjustment. be trusted to properly terminate and protect signal from mains cabling. On my last approach to the Electrical Workers Board, I let them know my background and offered to undertake any courses they considered would raise my skill level to enable myself to be registered as an electrician. The response was “it really doesn’t matter what you do or don’t know, the only way in is through an apprenticeship.” For similar reasons to the previous correspondent, please do not publish SC my name. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. 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. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. August 2000  91 REFERENCE GREAT BOOKS FOR NEW NEW NEW NEW AUDIO POWER AMP DESIGN HANDBOOK INDUSTRIAL BRUSHLESS SERVOMOTORS From one of the world’s most respected audio authorities. The new 2nd edition is even more comprehensive, includes sections on load-invariant power amps, distortion residuals, diagnosis of amplifier problems, and much more. 368 pages in paperback. Designed as a guide for professionals and a module text for electrical and mechanical engineering students. A step-by-step approach covering construction, how they work, how the motor behaves and how it is rated and selected. It may only be a small book but it has outstanding content! 186 pages in hardback. By Douglas Self. 2nd Edition Published 2000 By Peter Moreton. Publ. 2000 85 $ VIDEO SCRAMBLING AND DESCRAMBLING for Satellite & Cable TV by Graf & Sheets SETTING UP A WEB SERVER If you've ever wondered how they scramble video on cable and satellite TV, this book tells you! Encoding/decoding systems (analog and digital systems), encryption, even schematics and details of several encoder and decoder circuits for experimentation. Intended for both the hobbyist and the professional. 290 pages in paperback. NEW 2nd By Simon Collin. Published 1997. 65 $ Edition 1998 TCP/IP EXPLAINED Covers all major platforms, software, links and web techniques. It details each step required to choose, install and configure the hardware and software elements, create an effective site and promote it successfully. 273 pages, in paperback. 99 Assumes no prior knowledge of TCP/IP, only a basic understanding of LAN access protocols, explaining all the elements and alternatives. Combines study questions with reference material. Examples of network designs and implementations are given. 518 pages, in paperback. THE CIRCUIT DESIGNER’S COMPANION $ Includes grounding, printed circuit design and   layout, the characteristics of practical active and    passive components, cables, linear ICs, logic   circuits and their interfaces, power supplies, electromagnetic compatibility, safety and     thermal management.     302 pages, in    paperback. 65 LOCAL AREA NETWORKS: An Introduction to the Technology ELECTRIC MOTORS AND DRIVES Want to become more familiar with local area networks (LANs) without facing the challenge of a 400-page text? . Gives familiarity with the concepts involved and provides a start for reading more detailed texts. 191 pages, in paperback. For non-specialist users – explores most of the widely-used modern types of motor and drive, including conventional and brushless DC, induction, stepping, synchronous and reluctance motors. 339 pages, in paperback. By Austin Hughes. Second edition published 1993 (reprinted 1997). By John E. McNamara. 2nd edition 1996. O R D E R H E R E 69 $ By Tim Williams. First published 1991 (reprinted 1997). By Philip Miller. Published 1997. $ 99 $ NEW NEW NEW NEW 69 $  AUDIO POWER AMPLIFIER DESIGN...............................$85.00  INDUSTRIAL BRUSHLESS SERVO MOTORS..................$99.00  VIDEO SCRAMBLING/DESCRAMBLING..........................$65.00  TCP/IP EXPLAINED.........................................................$99.00  LOCAL AREA NETWORKS...............................................$69.00  SETTING UP A WEB SERVER..........................................$69.00  THE CIRCUIT DESIGNER’S COMPANION........................$65.00  ELECTRIC MOTORS AND DRIVES...................................$65.00  UNDERSTANDING TELEPHONE ELECTRONICS.................$59.00  AUDIO ELECTRONICS.....................................................$85.00  GUIDE TO TV & VIDEO TECHNOLOGY............................$59.00  EMC FOR PRODUCT DESIGNERS...................................$99.00  THE ART OF LINEAR ELECTRONICS...............................$88.00  INTERNET HOME PAGES MADE SIMPLE........................$27.00  DIGITAL ELECTRONICS ..................................................$65.00  ESSENTIAL LINUX..........................................................$85.00               ORDER TOTAL: $...................... TAX INVOICE 65 $ Your Name_________________________________________________ PLEASE PRINT Address ___________________________________________________ ____________________________________ Postcode_____________ Daytime Phone No. (______) __________________________________ STD Email___________________<at>_________________________________  Cheque/Money Order enclosed OR  Charge my credit card –  Bankcard  Visa Card  MasterCard No: Signature_________________________Card expiry date______/______ PLUS P&P (if applic): $.............. TOTAL$ AU.................... ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST BOOKSHOP WANT TO SAVE 10%? SILICON CHIP SUBSCRIBERS AUTOMATICALLY QUALIFY FOR A 10% DISCOUNT ON ALL BOOK PURCHASES! ENQUIRING MINDS! (To subscribe, see page 53) ALL PRICES INCLUDE GST UNDERSTANDING TELEPHONE ELECTRONICS THE ART OF LINEAR ELECTRONICS By Stephen J. Bigelow. Third edition published 1997 by Butterworth-Heinemann. $ 59 A very useful text for anyone wanting to become familiar with the basics of telephone technology. The 10 chapters explore telephone fundamentals, speech signal processing, telephone line interfacing, tone and pulse generation, ringers, digital transmission techniques (modems & fax machines) and much more. Ideal for students. 367 pages, in soft cover. AUDIO ELECTRONICS $ 88 By Lilian Hobbs. First published 1996. Second edition 1999. 85 $ All you need to get started. Create and design your own Internet home pages that include both text and graphics, using this practical, easy to follow, jargon free guide. This edition has been enhanced and updated and now covers HTML 4.0. 182 pages, in paperback. DIGITAL ELECTRONICS – A PRACTICAL APPROACH GUIDE TO TV & VIDEO TECHNOLOGY 59 Eugene Trundle has written for many years in Television magazine and his latest book is right up to date on TV and video technology. The book includes both theory and practical servicing information and is ideal for both students and technicians. 382 pages, in paperback. EMC FOR PRODUCT DESIGNERS By Tim Williams. First pub­­ lished 1992. Second edition 1996. Widely regarded as the standard text on EMC, this book provides all the information necessary to meet the requirements of the EMC Directive. It includes chapters on standards, measurement techniques and design principles, including layout and grounding, digital and analog circuit design, filtering and shielding and interference sources. The four appendices give a design checklist and include useful tables, data and formulae. 299 pages, in soft cover. P&P AUST: Add $A5.50 per book – Orders over $100 P&P free in Australia. NZ: Add $A10 per book, $A15 elsewhere 27 $ By Richard Monk. Published 1998. By Eugene Trundle. First pub­­lished 1988. Second edition 1996. $ 00 This practical handbook from one of the world’s most prolific audio designers has been updated and amended to make it the leading practical source of information for those interested in linear electronics and its applications, particularly in the world of audio design. 348 pages, in paperback. DESIGNING INTERNET HOME PAGES MADE SIMPLE By John Linsley Hood. First published 1995. Second edition 1999. This book is for anyone involved in designing, adapting and using analog and digital audio equipment. It covers tape recording, tuners and radio receivers, preamplifiers, voltage amplifiers, audio power amplifiers, compact disc technology and digital audio, test and measurement, loudspeaker crossover systems, power supplies and noise reduction systems. 375 pages in soft cover. By John Linsley Hood. First published 1993. NEW SECOND EDITION 1998. $ 65 With this book you can learn the principles and practice of digital electronics without leaving your desk, through the popular simulation applications, EASY-PC Pro XM and Pulsar. Alternatively, if you want to discover the applications through a thoroughly practical exploration of digital electronics, this is the book for you. A free floppy disk is included, featuring limited function versions of EASY-PC Professional XM and Pulsar. 249 pages, in paperback ESSENTIAL LINUX By Steve Heath. Published 1997. 99 $ Provides all the information and software that is necessary for a PC user to install and use the freeware Linux operating system. It details, setp-by-step, how to obtain and configure the operating system and utilities. It also explains all of the key commands. The text is generously illustrated with screen shots and examples that show how the commands work. Includes a CD-ROM containing Linux version 1.3 and including all the interim updates, basic utilities and compilers with their associated documentation. 257 pages, in paperback. 85 $ POST TO: SILICON CHIP Publications, PO Box 139, Collaroy NSW, Australia 2097. OR CALL (02) 9979 5644 & quote your credit card details; or FAX TO (02) 9979 6503 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FRWEEBE YES! Place your classified advertisement in SILICON CHIP Market Centre and your advert will also appear FREE in the Classifieds-on-the-Web page of the SILICON CHIP website, www.siliconchip.com.au And if you include an email address or your website URL in you classified advert, the links will be LIVE in your classified-on-the-web! S! D E I F I S C LAS EXCLUSIVE TO SILICON CHIP! CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $11.00 (incl. GST) for up to 12 words plus 55 cents for each additional word. Display ads: $27.50 (incl. GST) per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper, fill out the form & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy, NSW 2097. Or fax the details to (02) 9979 6503. Taxation Invoice ABN 49 003 205 490 _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my ❏ Bankcard   ❏ Visa Card   ❏ Master Card Card No. Signature­­­­­­­­­­­­ ________________________ Card expiry date______/______ Name _____________________________________________________ Street _____________________________________________________ Suburb/town _________________________ Postcode______________ 94  Silicon Chip FOR SALE RAIN BRAIN AND DIGI-TEMP KITS: 8-station sprinkler controllers. New Digi-temp and Moni-temp use DS1820 sensors. Feature PC data logging, 60 channels over 500 metres. www.mantismicroproducts.com.au ELECTRONIC/MECHANICAL DESIGN AND CONSTRUCTION: we offer a complete design service for electronic and mechanical devices. Most work is done in house and you deal directly with the designers. No job is too small and can be to prototype or “turn key” stage, in one offs or for future production. Simply send us an email at vladimir<at> u030.aone.net.au with your questions or requirements and we will get back to you. COVERT VIDEO SURVEILLANCE. Tiny Sub-Matchbox size Wireless Video & Audio TRANSMITTERS from $77 * Pinhole Cameras from $59. Easily concealed in: Mobile Phone Case, Clock, VCR Cassette, Toys, Teddy Bear (Nanny-Cam), Smoke Detector, Ornament, Cap, Cigarette Pack, etc. allthings.com.au 08 9349 9413. WEATHER STATIONS: Windspeed & direction, inside temperature, outside temperature & windchill. Records highs & lows with time and date as they occur. Optional rainfall and PC interface. Used by Government Departments, farmers, pilots, and weather enthusiasts. Other models with barometric pressure, humidity, dew point, solar radiation, UV, leaf wetness, etc. Just phone, fax or write for our FREE catalogue and price list. Solar Flair/Ecowatch phone: (03) 5968 4863; fax: (03) 5968 5810, PO Box 18, Emerald, Vic., 3782. ACN 006 399 480. C COMPILERS: everything you need to develop C and ASM software for 68­HC08, 6809, 68HC11, 68HC12, 68­ HC16, 8051/52, 8080/85, 8086, 8096 or AVR: $170.50 each. Macro Cross Assemblers and Disassemblers for above CPUs + 6800/01/03/05, 6502 and 68­HC12 for $88. Debug monitors: $88 for 6 CPUs. All compilers, XASMs and monitors: $5280. 8051/52 Simulator (fast, now incl. 80C320): $88. Try the C-FLEA Virtual Machine for small CPUs, build a “C-Stamp”. Demo desk: FREE. All prices + $5.50 p&p. Atmel Flash CPU Programmer: Handles the 89Cx051, 89C5x and 89Sxx series, and some AVRs in both DIP and PLCC44. Also does most 8-pin EEPROMs. Includes socket for serial ISP cable. $220 $11 p&p. SOIC adaptors: 20-pin $99, 14-pin $93.50, 8-pin $88. Credit cards accepted. GRAN­ TRONICS PTY LTD, PO Box 275, Wentworthville 2145. Ph (02) 9896 7150 or Internet: http://www.grantronics.com.au VIDEO CAMERAS: DOME COLOUR from $70 ! Mono from $48 ! BULLET from $85 with 2 YEAR WARRANTY * DOME: 480 Line 0.05 Lux with SONY CCD & ChipSet from $73 * 380 Line from $69 * 450 Line from $90 with 5 YEAR WARRANTY & BLEMISH FREE CCD * COLOUR DOME: 400 Line DSP from $126 * BETTER THAN SUPER-VHS Resolution 600 + Line DSP from $148 * 440 Line from $165 with 5 YEAR WARRANTY & BLEMISH FREE CCD * PINHOLE IN PIR DETECTOR from $111 * COLOUR DSP PIN in PIR CASE from $148 * MINI CAMS from $64 * 420 Line from $83 with 5 YEAR WARRANTY & BLEMISH FREE CCD * DSP COLOUR from $133 * 4 Ch Switcher from $78 * QUAD 1024 H-Pixels from $174 * COLOUR QUAD from $401 * Auto Scanner from $113 * REMOTE PAN & TILT from $239 * DIGITAL PC VIDEO RECORDER SOFTWARE & PCI CARD from $99 * MULTIPLEXER 4 Ch from $640 * REMOTE DIAL-UP, PAGING, WEB-CAM S/W & PCI CARD $199 * DIY PLUG-IN 20 metre AV Cable Sets from $18 ! UP TO 5 YEARS WARRANTY * OVERNIGHT DELIVERY * www.allthings.com.au * T 08 9349 9413 SOLAR PANELS: 120 watt $995.00, 80 watt $650.00, 60 watt $510.00, 40 watt $395.00 (all with 25 year guarantee). UNBREAKABLE PANELS: 64 watt $550.00, 42 watt $420.00, 32 watt $340.00, 11 watt $190.00, 5 watt $120.00, 1.25 watt $80.00. WIND GENERATORS: 400 watt $950.00. INVERTERS: sinewave inverters, inverter/chargers, mod. Sinewave invert- ROLA AUSTRALIA PH/FAX (08) 8270 3175 WEB SITE WWW.BETTANET.NET.AU/GTD CHECK OUR WEBSITE FOR DETAILS ON KITS AND COMPONENTS • • • • Silvertone’s RC Receiver Still the best little performer available! TRANSMITTER KITS AND MODULES AUDIO MODULES COMPUTER INTERFACE KITS RADIO STATION AUDIO SOFTWARE NEW: Our MP3-CD player in short form for $169 inc GST. Includes the following: processor board, front panel display and tactile keypad; just add a case, cables, 12V power supply and a CD-ROM drive. Play CDs and up to 2600 MP3’s from a CDR. Great for car or home. Satellite TV Reception International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. Still only $129.50 AM or $149.50 FM. May be used with most ppm transmitters. This and many other radio control products available from: Silvertone Electronics, PO Box 580, Riverwood 2210. Phone/Fax (02) 9533 3517. www.silvertone.com.au AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au Positions At Jaycar We are often looking for enthusiastic staff for positions in our retail stores and head office at Rhodes in Sydney. A genuine interest in electronics is a necessity. Phone 02 9743 5222 for current vacancies. ers, call with requirements. AUST­RALIA WIDE DELIVERY (Free on orders over $500.00). Note: prices DO NOT include GST. TASMAN ENERGY: (03) 6362 3050 Fax (03) 6362 3054. Need prototype PC boards? We have the solutions – we print electronics! Four-day turnaround, less if urgent; Artwork from your own positive or file; Through hole plating; Prompt postal service; 29 years technical experience; Inexpensive; Superb quality. Printed Electronics, 12A Aristoc Rd, Glen Waverley, Vic 3150. Phone: (03) 9545 3722; Fax: (03) 9545 3561 Call Mike Lynch and check us out! We are the best for low cost, small runs. KITS KITS AND MORE KITS! Check ‘em out at www.ozitronics.com TELEPHONE EXCHANGE SIMULATOR, SC February 1998. Test equipment without the cost of telephone lines. Melbourne 9806 0110. HOME CCTV Mono/Colour PAKS Only! $113/$140. DIY Plug-In to TV/ VCR, 20 metre cable, Plug Pack & Camera. www.allthings.com.au T (08) 9349 9413. RCS HAS MOVED to 41 Arlewis St, Chester Hill 2162 and is now open, with full production soon. Tel (02) 9738 0330; Fax 9738 0334. rcsradio<at>cia.com.au; www.cia.com.au/rcsradio DIY CCTV PAKS 4 Cameras & Switcher ............... $315 as above COLOUR ................... $419 4 Cams, Switcher/Monitor .......... $433 as above 14" Monitor ............... $461 4 Cams, QUAD & Monitor .......... $602 4 COLOUR & QUAD .................. $797 MORE at: www.allthings.com.au Fully Plug-In DIY Paks with all Cables & Power Supplies ALSO PC Digital Motion/Sound detection & activated Video/Audio Recording systems 08 9349 9413. KIT ASSEMBLY ANY KITS assembled/repaired: professional, speedy service. Phone Nev­ille Walker (07) 3857 2752. WANTED PERSON WITH EXPERIENCE / APTITUDE able to fault find & repair PCBs – without diagrams. GENEROUS PKG NEG. Tel John<at>AER (03) 9482 4958 0415 305 470. August 2000  95 Silicon Chip Binders Keep your copies safe, secure and always available with SILICON CHIP binders: they’re cheap insurance! Advertising Index Altronics................................. 66-68 REAL VALUE AT Av-Comm Pty Ltd.........................95 PLUS P &P EMC Technologies.......................83 $12.95  Heavy board covers with 2-tone green vinyl covering Dick Smith Electronics............. 8-15 Emona Instruments...................IBC  Each binder holds up to 14 issues so that you can include catalogs Evatco..........................................87  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Instant PCBs................................95 Harbuch Electronics....................81 Investment Technology................31 Jaycar ................................... 45-52 Price: $12.95 (includes GST) plus $5.50 p&p each (available Aust. only). Price includes GST. Kalex............................................87 Order by phoning (02) 9979 5644 & quoting your credit card number; or fax the details to (02) 9979 6503; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Kits-R-Us.....................................95 Microgram Computers..........3,OBC MicroZed Computers...................83 Namlea Data Systems........... Insert Oatley Electronics........................61 DON’T MISS THE ’BUS Do you feel left behind by the latest advances in com­puter technology? Don’t miss the bus: get the ’bus! Includes articles on troubleshooting your PC, installing and setting up computer networks, hard disk drive upgrades, clean installing Windows 98, CPU upgrades, a basic introduction to Linux plus much more. Optional Power.......................37,77 www.siliconchip.com.au SILICON CHIP’S 132 Pages 9 $ 95 * ISBN 0 95852291 X 09 9780958522910 09 9 780958 INC LUD ES FEA TUR E LIN UX A collection of computer features from the pages of SILICON CHIP magazine Protel ........................................IFC Questronix...................................43 Rall Electronics............................83 REC Electronics..........................77 RobotOz......................................83 R.T.N............................................83 Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NT NO W o AVA DIRE ILABLE C SILIC T FROM ON just $ CHIP 125O INC RT P&P Note: price includes the GST. HELP SAVE THE NIGHT SKY! We are losing our heritage of starry night skies. Poor, inefficient outdoor lighting is causing glare and “light pollution”. This wastes energy and increases greenhouse gas emissions. You can help by joining SYDNEY OUTDOOR LIGHTING IMPROVEMENT SOCIETY (SOLIS). SOLIS aims to educate and inform about quality outdoor lighting and its benefits. We also lobby councils, government and other bodies to promote good lighting practice. SOLIS meetings are held third Monday night of each month at Sydney Observatory. Individual membership is $20 pa. Donations are also welcome. Cheques payable to “SOLIS c/- NSAS”, PO Box 214, West Ryde 2114. 96  Silicon Chip Printed Electronics...................... 95 522910 COMPUTER OMNIBUS ORDER NOW: Use the handy order form in this issue or call (02) 9979 5644, 8.30-5.30 Mon-Fri with your credit card details. Email: tpeters<at>pip.elm.mq.edu.au Premier Batteries....................41,83 SC Electronics Testbench............69 SC EFI Tech Special....................44 Silicon Chip Binders....................96 Silicon Chip Bookshop........... 92-93 Silicon Chip Subscriptions...........53 Silvertone Electronics..................95 Smart Fastchargers.....................43 Solar Flair/Ecowatch....................94 Vass Electronics..........................83 _____________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730. August 2000  97