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Making old homes data friendly SILICON CHIP OCTOBER 2000 6 $ 60* INC GST ISSN 1030-2662 NZ $ 7 50 10 INC GST PRINT POST APPROVED - PP255003/01272 9 771030 266001 siliconchip.com.au PROJECTS TO BUILD - SERVICING - COMPUTERS - RADIO - AUTO ELECTRONICS r u o y h it s i w h t g n h lo CD wit a m a J e t i r u o fav * TINY SPY CAMERA for peering into nooks and crannies!! October 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 1 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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.fluke.com.au Contents Vol.13, No.10; October 2000 FEATURES 4 DrDAQ: It Turns Your PC Into A Science Lab Use it for science experiments or as a general-purpose, easy-to-use data logger – by Peter Smith 10 Structured Data Cabling For The Home Bringing your home into the 21st century – by Ross Tester 70 Drive By Wire: Electronic Throttle Control, Pt.2 A look at the control system logic – by Julian Edgar 78 Review: Altronic’s Aussie-Made PA Amplifiers Guitar Jammer For Jam Sessions – Page 22. They’re even exporting these beauties to Asia – by Ross Tester PROJECTS TO BUILD 22 Guitar Jammer For Practice & Jam Sessions Build it and jam along with your favourite CD, or use it to practice without disturbing others – by Leo Simpson & Peter Smith Booze Buster Breath Tester – Page 28. 28 Booze Buster Breath Tester Use this fun device to test your soberity, err sobrity, err how much you’ve had to drink but don’t rely on it to drive – by Ross Tester 38 I Spy With My Little Eye . . . Peer into hidden nooks & crannies with this tiny inspection camera built into a flexible wand – by Ross Tester 53 Installing A Free-Air Subwoofer In Your Car You don’t need to take up lots of room with a big box; this uses the boot as the enclosure. And it works! – by Julian Edgar 60 Protoboards: The Easy Way Into Electronics Use a protoboard to build a siren & alarm timer – by Leo Simpson 66 Fuel Mixture Display For Cars, Pt.2 All the construction details & calibration procedures – by John Clarke SPECIAL COLUMNS 34 Serviceman’s Log Two Teacs before bedtime – by the TV Serviceman Wand-Mounted Inspection Camera – Page 38. 82 Vintage Radio A battery eliminator & a simple servicing aid – by Rodney Champness DEPARTMENTS 2 9 58 74 77 Publisher’s Letter Mailbag Circuit Notebook Product Showcase Electronics Showcase 81 88 90 94 96 Subscriptions Form Ask Silicon Chip Notes & Errata Market Centre Advertising Index Installing A Free-Air Subwoofer In Your Car – Page 53. October 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 The health record card – what a smart idea Recently, there has been quite a lot of discussion about the adoption of electronic storage and transfer of medical infor­mation for all Australians. The idea has been greeted cautiously by the medical profession but there are reser­vations. What we are talking about is a complete cradle-tothe-grave medical record which will be accessible each time you visit your doctor or require any sort of health care. Yes, there are all sorts of possible drawbacks – loss of privacy, the possibility of information being passed to third parties, insurance companies, Government social security link-ups and so on. But think about the positives. Privacy is just about gone in our society, anyway. Just say you had a smart card with all your medical history on it. I’m not just thinking about the sort of stuff recorded on a card file at your doctor’s surgery. It would also contain details of every operation, every visit to your local hospital’s outpatients’ department, every sporting injury, X-rays, all your dental records, optical prescriptions and even any herbal treat­ments you might have had. I’ll bet that most people have little knowledge of their childhood ailments and treatments, the number of fractures and sprains, torn ligaments and dislocations they might have suf­fered. In my own case, I know that I have had a couple of minor operations 15 or more years ago but I cannot remember all the details, precisely when they occurred, the surgeons who performed them and so on. And nor can I remember the times and details of when I might have visited hospital casualty departments to have stitches when I walked through a glass door at night, when I dislocated my shoulder and so on. As with most people, I have had several local doctors over the years and nowadays, most people just tend to visit the local medical centre for treatment. So most people would have disparate medical records spread over various doctors, medical centres, hospitals, dentists, in different cities and states and so on. It would be great to have all this information together and on tap whenever you visit the doctor. He or she would zip the card into the computer, run through the records, make any diagno­sis and prescribe treatment. All this would then be recorded in three places: on your own health card, at the doctor’s surgery and in a central database. Think about the ramifications of this. First, any diagnosis and treatment should be more correct. Multiple and conflicting drug treatments for different ailments should be avoided. If ever you were wheeled unconscious into a hospital casualty department, they could immediately call up your complete medical records and they would know which drugs to avoid, which drugs to apply (for ongoing treatment of existing conditions) and so on. Your chances of survival in such a situation would be much better. But the system could be enhanced further. It could incorpo­rate family medical history as well, so that it would highlight any long term diseases (cancer, blood pressure, etc, etc) that you might be prone to. It could even have your DNA! You might even be able to plug the card into your own com­puter which then would periodically prompt you to have a checkup, take your medicine, visit the dentist and so on. Ultimately, doctors might employ software to scan your card and current symptoms and then suggest possible diagnosis and treatment – as a backup to the doctor, of course. Ultimately, such a system would be a great advance in the health treatment of the nation. Sure there are possible drawbacks but I think the positives would outweigh the negatives. It could all be developed in Australia and then sold to the rest of the world. Now that would be something! Leo Simpson                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            October 2000  3 DrDAQ It turns your PC into a science lab Would you like to use a computer to perform lots of interesting science experiments without spending megabucks? Or perhaps you just need a general-purpose, easy-to-use data logger for home or lab? DrDAQ can ease the pain! REVIEWED BY PETER SMITH D R WHO? Yes, it is an unusual name. But DrDAQ is just one of a whole host of data acquisition devices currently available from the respected UK company Pico Technology. Pico Technology has been manufacturing PC-based (hence “virtual”) instruments for data acquisition since 1991. PC-based test and data acquisition equipment is quickly emerging as the most 4  Silicon Chip cost-effective approach to high quality instrumentation. DrDAQ is a perfect case in point. Here’s why. What is a data logger? Generally, data loggers provide a means of making and storing real-world measurements over a period of time. With the right type of transducer (or sensor), any kind of physical quantity can be measured – temperature, pressure, radiation, acceleration, etc. Having made and stored (logged) the measurements, we must then be able to display them in an easily understandable way. This means charting and graphing the data, and perhaps performing mathematical manipulations as well. Actually, the term “data logger” describes only part of what DrDAQ can do. For example, it can also display measurements in real time on an oscilloscope-like display. The package consists of both hardware and software components. Lets look at the hardware first. Hardware The hardware consists of a single PC board measuring just 55 x 70mm. It plugs into the parallel (printer) port of your PC via a 2-metre cable and requires no external power. A thick foam-like pad glued to the rear of the PC board protects the majority of the workings from physical damage, as it’s not enclosed in a case. We’ll see why in a moment. Included on the board are nine analog inputs and two digital outputs. Four of these inputs are connected to sensors located right on the board! Sound, light and temperature sensors enable you to begin experimenting immediately. Also included are connectors for two additional external temperature sensors (or user-defined sensors) and a standard-type pH probe. External sensors can be purchased from Pico Technology as required. A screw-type terminal block provides connection for the remaining two inputs, one measuring voltage and the other resistance. Access to one of the two digital outputs is also provided on the terminal block, with the other driving an on-board LED. Tables 1 & 2 show the analog input and sensor specifications. Software Our preview copy of DrDAQ software was supplied on three floppy disks but the full release (available as we write) will be supplied on CDROM. It runs on Windows 3.1x, 95, 98, NT and 2000. No particular hardware requirements are listed, although you will need a free parallel port for connection to the DrDAQ hardware. If you only have a single parallel port and it’s already in use, you can either purchase an add-on parallel port card or a switch box – or switch cables manually if you have more patience than I do! As with most Windows software these days, installation is a breeze. You simply launch the setup program and follow the on-screen prompts. The software is divided into two distinct modules, defining the two major functions of this package. PicoLog provides the data logging functionality and PicoScope the real time display. Logging data PicoLog consists of a recorder for sampling and storing data and a player to display the results. Although the player software is integrated in the recorder, a separate player is also included, which means that you can view previous recordings while another is in progress. Before logging can begin, PicoLog’s recorder needs to know where to store the data as it’s measured, as well as which inputs to sample, how often they should be sampled and how many samples to make. Other parameters such as scaling and units of measure are also important, as the player will use these when graphing the results. Let’s briefly look at the available settings. Setting up All settings are accessed from the main menu (see Fig.1) and can be saved in a unique file for later recall. For our tests, we decided to monitor the sound, temperature, light and pH sensors (see Fig.2). As you can see, the digital outputs are also configured here, with options of “always on”, “on when recording”, “on when alarm” or “off when alarm”. Highlighting any of the measurements and hitting the Edit button brings up scaling, measurement (AC, DC or frequency, depending on the selected sensor) and scan time options (see Fig.3). If measuring the DrDAQ sensors, PicoLog configures most of these settings for you. For cases where you’re measuring Fig.2 (left): multiple channels can be measured simultan­eously. Just add them in here and hit the edit button to configure. Fig.1: all settings are accessible from the main Recorder window and the large buttons on the toolbar provide quick access to often used functions. October 2000  5 Fig.3: PicoLog completes most settings for you if measuring a known sensor. If you get stuck, the Help button is always handy. Fig.4: the Edit button in Fig.3 brings us here and this is about as tricky as it gets. This is where we define what is needed to make the output from the player (the graphs) look right! Fig.5 (above): setting the sampling rate, and hence the number of points that will eventually be plotted on the graph. Fig.6 (right): results of our tests from PicoLog Graph. Don’t be fooled by our rather compressed view – graphs can be much larger than this if need be. Note the scrolling and zooming buttons on the right ride of the window. custom sensors, PicoLog provides additional options for setting units of measure, scaling and numbering (see Fig.4). It’s even possible to read scaling values from an external file for non-linear measurements! Also of interest here is the alarm feature. This sounds an alarm (the PC speaker “beeps”) when any of the measurements are outside predefined upper and lower limits (as defined by the user). If enabled, alarm conditions can toggle the digital output lines, too (see above). The rate of measurement (sampling interval) and the total number of measurements to be made are configurable from the main settings menu (see Fig.5). Intervals from milliseconds to hours are programmable, with a maximum of one million samples! We’ve tried not to bore you with detailed explanations of every setting 6  Silicon Chip here, as the on-line help is indeed helpful and Pico Technology have included a “Guided Tour” to ease you into the driver’s seat. Even better, you can test drive a working demo off the DrDAQ website – but more on that later. Once setup is complete, it’s just a matter of clicking on the “record” button on the main menu to start recording. You can keep an eye on what is happening during recording by enabling the “monitor” setting for channels of interest (see Fig.1). Getting results Displaying the results of a recording is very straightforward. Simply launch the PicoLog Player, load the recorded data file from the main menu and hit either the “graph” (Fig.6) or “spreadsheet” (Fig.7) buttons. Graph displays can be scrolled up and down, magnified or reduced and printed at will. The entire image (minus the ugly frame) can be copied to the Windows clipboard and pasted into any popular application. The spreadsheet mode provides a nice tabulated display of the recording. It also allows the data to be saved in standard text format – a must for advanced users who wish to do further processing in other applications. Real-time display A real bonus with this package is its ability to display measurements in real time. This feature (called Pico­ Scope) is often only available on more expensive virtual instruments and despite the relatively low sampling rate of the DrDAQ hardware (10kS/s), it could still be a very useful instructional tool. Samples can be displayed in a vari- ety of different ways, called “views” (see Fig.8). To summarise, these are: (1) Scope view: samples are displayed in an oscilloscope-like format (amplitude versus time). The horizontal timebase can be set up just like a regular ’scope, with a 10 x 10 grid and selectable intervals of 1ms to 50s per division. Alternatively, you can set the timebase in terms of time per complete sweep if preferred. The vertical axis displays amplitude in millivolts. The scaling can be easily customised, allowing direct display in any units you desire. For example, if measuring a pressure sensor, the vertical axis could be marked in kPa. The sampled data can be displayed in a number of different formats. These are: • Current – the current cycle of data. • Average – the average of all cycles since you started. • Minimum & maximum – a shaded area representing the minimum and maximum of all cycles since you started. • Accumulate – draw each current cycle without removing the previous one. As well, more than 20 calculated measurements can be performed on either the whole waveform or part of the waveform (selected with moveable cursors). The results are displayed at the foot of the waveform. Some examples of calculated measurements are frequency, high pulse width, low pulse width, duty cycle, rise time, etc. Also of note is the chart recorder mode, which is automatically assumed when the sampling rate is longer than one second. This mode is perfect for slow changing inputs such as those from temperature sensors. (2) Spectrum view: samples are displayed in spectrum analyser format (amplitude versus frequency). Mathematical calculations (called FFTs) are used to convert sets of samples taken at fixed time intervals into a distribution showing the amount of energy in a range of frequency bands. For this view, the Y-axis represents power and can be set to either volts RMS or decibels. The X-axis represents frequency, displayable in either linear or logarithmic format. We did notice that our mouse froze for a brief moment each time a spectrum window was updated (presumably because of the complex Fig.7: this is what the Spreadsheet output looks like. Logged data can be saved in a text file or pasted directly into other applications. calculations involved), so watch out for this if you intend running multiple spectrum windows on a slowish PC. (3) XY Scope view: in this view, samples from one channel are plotted against samples from another. This means that both the X and Y-axes represent amplitude (in millivolts). (4) Meter view: as the name suggests, this view displays the desired channel in a digital, meter-like format, complete with bargraph. AC, DC or frequency measurements are possible. Meter views “know” about DrDAQ sensors and will, for example, display temperature sensor inputs directly in °C. (5) Composite view: a copy of up to four active views can be displayed in a single composite view. A variety of formats such as side-by-side and overlay are supported. This is useful for printing multiple views on a single page, or performing before and after waveform comparisons. Any analog input (channel) can be displayed in its own scope, spectrum or meter window. In addition, multiple views of the same channel are supported, so you can, for example, display a channel in both a scope and meter view simultaneously. Samples can be displayed either continuously or after a particular condition occurs. This is called “triggering” and is indispensable The DrDAQ hardware with PC parallel port cable and two external sensors connected. The black object between the white and grey connectors is a tiny electret microphone. The light sensor is the tiny round object to the left of the black screw-terminal block. Immediately to the left of the light sensor is a glass-encapsulated thermistor which is used for temperature sensing. October 2000  7 examples from the physics and chemistry sections: Physics • • Measuring the speed of light. Measuring the speed of sound using a musical recorder. • Magnetic Induction – dropping a magnet through a coil. • Measuring the swing of a pendulum. • Battery discharge – which battery lasts the longest? • Electromagnetism – experiments with a Bicycle Dynamo. • Light intensity variation across a diffraction pattern. • Wind resistance and terminal velocity. • Measuring heat transfer coefficient. • Measuring the value of a capacitor. • Sensing the speed and acceleration of a train. • Wave speed in a solid using a hammer to measure a pulse travelling down a metal bar. Fig.8: displaying inputs in real time. Three different views are shown here using six windows. In the bottom right corner, three meter views show the temperature from the on-board and two external temperature sensors. The Scope view above these shows the output from the light sensor – in this case, the 100Hz flicker of our office fluorescent lighting is being measured. The Spectrum window at bottom left is also displaying the light sensor output, with the window above that displaying the sound (microphone) sensor output. for viewing random or intermittent events. Any channel can be selected as the trigger source. Triggering can be set to occur at a particular input signal level (threshold), either rising or falling. Even better, you don’t have to remain glued to the display waiting for that intermittent event because Pico­ Scope can automatically save the samples to disk when the trigger occurs. Samples are stored in sequentially numbered files for easy recovery and viewing or printing, just like live waveforms. 8  Silicon Chip Freezing of pure and salt water. Measuring the pH of milk at it turns sour. • Monitoring the rate of reaction between two liquids. The DrDAQ web site is continually updated with new experiments as they become available and includes many ideas for experiments of your own. Check it out at www.DrDAQ.com! Like to know more? The DrDAQ product comes with free lifetime technical support, free software updates from their website and a 2-year return-to-manufacturer warranty on the hardware. You can also try before you buy with free demo software (complete with simulated data) from http://www. drdaq.com/download.html Are you already familiar with data loggers and have a specific application in mind? Write your own software using DrDAQs DLL drivers for Windows. Examples in C, Delphi and Visual Basic are included! Once again, these are free to download from the DrDAQ website. Putting DrDAQ to work Pico Technology has developed DrDAQ primarily for the education market and it shows. As well as PicoLog and PicoScope, the software CD includes a whole host of interesting science experiments that can be performed using DrDAQ. The experiments are grouped into categories such as Biology, Chemistry, Physics and General Science. Experiments include both teacher and student versions. Here are some Chemistry • • Where to get it Another view of DrDAQ. The “brains” of the unit consists of surface-mount components which are hidden on the back of the board. DrDAQ is available from Emona Instruments. Check out their website at www.emona.com.au or phone (02) SC 9519 3933. MAILBAG Problems with SILICON CHIIP Email Towards the end of August and the start of September, we received a number of complaints regarding our response to email and the operation of our website at www.siliconchip. com.au One person even posted messages on an electronic chat site asking whether SILICON CHIP had gone belly up. In fact, we have had quite a lot of trouble with our email in the month of August and also in the preceding months. We do not know how much email went astray but it is clear that many people did not receive a “bounce-back” message stating that the email was undeliverable. It is probable that the email was deliv­ered to our host site but unfortunately, it did not come down the wire to the SILICON CHIP office. And since we did not respond, people thought that we were ignoring them. For similar reasons related to our web host, our website has had problems, particularly if people wanted to do downloads. As a result of this, we transferred our website and email to a new host server in early September. By the time this issue goes on sale, we hope that all these problems will be solved. If you sent in an email in the last few months and received no response, please try again. And if you still receive no re­sponse or bounceback messages, please phone us. SILICON CHIP. Electrical Licensing Board Not Realistic I was rather bemused to read of the recent ructions going on in regard to the Queensland Electrical Licensing Board, as featured in recent issues. I wish to share a brief interlude I had with them, with your readership. It was some ten or so years ago, when I lived in Brisbane. I had been working in the business machine industry, primarily as a salesman, for several years when I applied for their “restricted” license. From memory, I was required to present myself at a nearby TAFE college (after paying a non-refundable application fee – around $25.00 I think!) and show the examiner that I had a rea­ sonable knowledge of basic electrical theory and practice. This amounted to answering some questions, using an oscilloscope to measure mains voltages from a wall outlet and then attempting to wire a 3-pin plug, to the satisfaction of the examiner; simple enough, if you were worth your salt. I was somewhat taken aback when a refusal letter came in the mail, explaining to me that “because I wasn’t actually in the job (in their estimation) I couldn’t sit for their test”. Because I didn’t have the licence, I could no longer perform some of the tasks I used to do, when backing up the service people in our workshop, when sales were a little quiet. Any thoughts of working for someone else, for example, in the entertainment (read pinball machine) industry were also thwarted, as they too were required to employ “licensed” staff (for pinball machine repairs!). I remember ringing the “Board” and talking to a nice per­son, who very firmly argued with me the pros and cons of electri­cal safety. I informed this person that I wasn’t undertaking any particularly dangerous tasks in the workplace (no mains wiring or repairs as such) and had, as a hobbyist for many years prior, already survived a few rather nasty shocks by taking the usual precautions (one hand in the pocket wearing rubber soled shoes). This brings me to another salient point. In our modern 21st century world, we have a proliferation of safety devices, such as core balance relays (even portable units nowadays) that can disconnect fatal currents within milliseconds. I feel that a lot more emphasis promoting this area of electrical safety to the industry, as well as to commercial and domestic appliances users, would be time well spent by the various ELBs around Australia, rather than trying to chase “electronics shadows” (unlicensed people) who have so far seemed to have eluded them. While doing a year at Newcastle TAFE (pre-apprenticeship electronics) back in 1980, one of our primary projects for second term was the building and successful operation of a mains-operated variable DC power supply. How did students at Queensland TAFE get on that year? Were they forced by the old boy’s club back at the ELB to get a restricted licence at that early stage? Before moving to Brisbane in 1986, I worked at a sizable Telecom exchange, where the main power bus bars carried 48V DC at around 1800A, during the busy hour. Try dropping a spanner across that wiring and see how you’d get on. It seems that the Queensland ELB’s standards relate only to smaller AC and DC voltages, with no mention of important current ratings in their restricted licence standards, not to mention the absence of any standards relating to communications equipment that may be off-site (ie: outside of a Commonwealth owned and operated installation) and therefore deemed to be within the respective state’s jurisdiction. If there is a “line drawn in the sand” between state and federal regulators, where is it? While federal regulators such as the ACA may well cover communications wiring standards, where does that leave the poorer cousin known to us only by the nebulous term of “electrical safety”? As for the building of various kits, many people nowadays use AC/DC plugpacks, with the simple addition of basic components for rectification, filtering and regulation. No real danger there. A. Hellier, Warilla, NSW. October 2000  9 Structured the Home... or dra In August SILICON CHIP we looked at Structured Cabling and its place in the modern office. Did you know that exactly the same principles apply to the data and communications wiring in your own home? By Ross Tester T his all started not long ago when my daughter and son-inlaw bought their first “real” house. All very exciting, of course, after living in a third-floor unit since they were married (not to mention better for me – how I hated those six flights of stairs!). It is a reasonably old house and while a bit of spit and polish made it perfectly liveable, it suffered from 20th century wiring. Most obvious was the lack of power outlets – for example, just two in the kitchen (and one of those was for the ’fridge). But just as noticeable (at least to me after my adventures last month with structured cabling systems and the “miniLAN”) was the complete lack of communications and data cabling. Of course, neither of these problems were overly surprising. Back when this home was built they only put one power outlet in each room because there wasn’t the proliferation of appliances and devices of today. And as for data, well, home computers hadn’t even been invented yet; TV was in its infancy (no family had more than one, if that) and what was a VCR? It’s only in recent times that builders of new homes have started to put in almost as many power outlets as PIC TO COME Superb under-floor access meant no crawling around – in fact, a ladder was needed to reach the floor above! Inset is a close-up of one side of the garage: lying on the floor is just some of the dangerous wiring we removed. Ignore the rest of the junk – the garage proved too tempting to store stuff while moving in... 10  Silicon Chip Cabling for agging home wiring, kicking and screaming, into the 21st century needed (Murphy’s law again – the number of power points in any given room is always n-1, where n is the required number). And it’s only in very recent times – if at all – that builders of new homes have started to worry about data and communications cabling. As we said last month, while building is in progress is by far the best time to take future needs into consideration. An extra couple of hundred dollars’ worth of cable and sockets while access is dead easy could save a lot of heartaches in the future – when it’s not! But this was not a new house. Sure, they were planning on giving it a bit of TLC – as much as their budget would stretch, that is. But I thought it would be a good opportunity to put my new-found knowledge on structured cabling to the test, in a domestic (as distinct from a business) situation. What’s more, it could be grist for the SILICON CHIP mill: perhaps readers would like some ideas of what they could do themselves? “Would you like to have your home data and communications wiring updated?” I asked. “How much will it cost?” was their reply. “Not much at all,” I said. “Well, if you think so… but we really need someone to have a look at the power wiring as well...” Now I have a mate who’s a licensed electrician and Austel-approved cabler and he owed me a favour or two. For the cost of any materials, he would do what was required if I supplied the labour. And we had a long weekend coming up! Access One of the reasons I had “volunteered” to help out the kids was the outstanding under-floor access. The house is built on a slope with much of the under-side occupied by a double-width, very long garage (you’d fit six cars in it if you tried). No crawling around in the dark in this place. That’s probably fortunate because the house is built in an area known locally as “spider hill” – it contains possibly the largest concentration of funnel-web spiders in Sydney! Anyway, my mate and I reconnoitred the place to check out what we had in store. Power wiring What we found first made us shudder. While some of the place was wired well, it was obvious that someone who really didn’t have a clue had “had a go” at installing some new wiring. There was building cable simply draped from bearer to bearer (hey, cable clips cost money!) and, far worse, ends of cables hung down in various places protected with nothing more than insulation tape. It didn’t take too long to identify where these dangerous cables were connected and simply remove them altogether. That done, we proceeded to re-cable where necessary and install new power points as required. We also took the opportunity to remove the existing mishmash of light fittings (which my daughter hated) and replace them with new ones. That wasn’t too much of a challenge – but the fitting in the lounge room with its completely exposed live wiring and connectors, well that made us think twice. This place has very low ceilings – a tall person could easily reach up and touch live terminals! Needless to say, that problem was fixed. There was one problem which wasn’t fixed: a mysterious architrave switch just inside the back door. Try as we might, we could not work out what this switch did nor where the wires travelled. No, it’s not an external light – we found the cabling and switch for that elsewhere. Nor is it a two-way switch for something else – we couldn’t make it do anything. About all we know is that it has active and neutral coming in, switched active and neutral going out – but to where? Light cabling is in the ceiling but this place has a flat metal roof only 150mm above the ceiling, so there is no access. One of these days, when the rusting roof is replaced, we might find out! Until then, we decided to leave well enough alone. Data/communications wiring The power side completed, we Someone had tried their hand at wiring in the past: building wire simply draped over bearers, live wires hanging down “protected” only by insulation tape... it was enough to make you shudder! October 2000  11 of the house. It disappeared through a hole drilled right through the wall (ugh!) into a wall plate outlet simply lying on the floor in probably the worst position in the lounge room. That would have to go. Before ripping the cable out, we decided to check the signal level and to our surprise found rock-solid, ghost free reception (this area is not renowned for good signal, especially on VHF). That was fortunate because they had two (possibly three) TV sets and two VCRs to connect. We might even be able to get away with splitters and no amplifier. But we would still have to run new coax cable to where it was required. Audio Just like the "miniLAN" in our last issue, the heart of a structured cabling system for the home is a patch panel. This is the KRONE Broadway, complete with smoked perspex cover. Clipsal’s “Starserve” is somewhat similar – see separate panel. now turned our attention to the data and communications side which, of course, is the main reason for this story. The previous occupants of the home ran a business and had three tele-phones, all on their own exchange lines (no, we don’t think they were SP bookies!). There were two cables coming in from the street, one a single pair and the other a four-wire. The first line had been properly installed, nicely cable-clipped to a floor bearer all the way until it disappeared up a hole to go to a phone socket on a skirting board above. The other cable was much like the power wiring we had found, simply draped over bearers and terminated in a pair of Telecom 610 sockets also hanging in thin air below a floor joist. There were a couple of holes drilled straight through the floorboards above which had probably once had cables going through them to sockets upstairs, but they weren’t there now. TV Next it was time to look at the TV installation. There was an old VHF antenna mounted on a weird contraption of pipework on the roof with a balun and 75Ω cable running down the side This version of the Broadway, shown here with the outer cover removed, is set up for five zones (it can handle up to ten). To add extra zones or services it is simply a matter of cutting out the label and inserting extra sockets/connectors (the metalwork underneath is pre-punched). 12  Silicon Chip Another surprise was a pair of figure-8 cables which ran from the front of the house to the back, ending up in a flexible conduit which disappeared under the back wall. We managed to trace this out to the pool area where it ended in bare wires, again hanging in midair. The other end, under the house, was also hanging in midair but immediately above were two more holes drilled straight through the floor. We surmised that these cables once connected to a hifi system with speakers connected near the pool “on demand”. At least we hoped that’s what they were for! OK, it was time to gather our thoughts. We had repaired, removed or replaced any mains wiring which needed it. We had three telephone Opening the door reveals a range of punch-down sockets for incoming and outgoing services, along with a Disconnect Module (a punchdown connector for incoming ’phone lines) and two splitters/combiners for RF (coax) services. Fibreoptic is also available – nice to know for future expansion. My “mud map” of the kid’s house with all of the services, both incoming and distributed, to be handled by the stuctured cabling system and coax cable. This is to a large degree a “wish list” with all the things they could think of that they might like in the future (like four TV sets – and a pool camera: they don’t even have a pool yet!). lines coming in from the street, only two of which would ever be used (one for phone, one for fax/modem). We had a pair of figure-8 cables which we presumed were audio. And we had an old TV antenna with a short down-lead ending in the wrong place. Taking stock Now we had to look at their data and communications requirements. They wanted TV outlets in the lounge-room and two of the three bedrooms – with the option of an outlet in the other bedroom if possible. They wanted to be able to dub from one VCR to the other, even though they were to be many metres apart (no, of course they wouldn’t record any copyrighted material. Nobody does that!) They wanted the existing phone socket moved, another socket on that line in the main bedroom and one of the spare lines moved to the computer desk in one of the bedrooms for the fax and modem. And then they remembered they wanted cabling placed to allow a security system to be installed and, while we were at it, what about the audio cabling? Could it go elsewhere in the house as well so that extra speakers could be installed later? Now this was starting to become a pretty tall order. There would be cabling everywhere – phone lines, data lines, TV coax, audio cables, security cables. It could easily turn into a nightmare. Structured cabling Then my mate said “What about running as much as possible in Cat5?”. At the time I only had a vague idea what Cat5 was – the cabling used for computer networks. (All this was before we covered the MiniLan system last month.) But running phones, data, audio, security, perhaps even video, all on Cat5? “No problem,” he said. I hate it when someone says no problem. That’s usually when the problems start. But he assured me that what he was proposing was not only perfectly practical, it was the most economic method, certainly the most flexible and also the neatest into the bargain. It’s a system called structured cabling, which simply means installing a cabling system independent of the services it carries, the equipment it serves or even the building layout. Most modern office buildings are being wired using structured cabling and now it’s the turn of the home. (See the article on Structured Cabling in last month’s SILICON CHIP). What it means is that you install cabling to cover just about anything that you can think of, now and in the future. One end is terminated in a patch panel of some description (we’ll describe this shortly) while all the other ends, wherever they go to, end in jacks mounted on wall plates. The wiring is done using Cat5 caOctober 2000  13 The wallplate fits a standard mounting block or plate. Here we are using a plasterboard mount with a standard Clipsal/ HPM 4-way plate. Yeh, we could have moved the desk first! ble, which contains four unshielded twisted pairs (UTP), each wire colour coded to its mate. That means at any wall outlet you could have up to four different devices connected, depending on which pair they connect to. A voice telephone, for example, would normally be connected to the centre pair of connectors (4 & 5) which are wired to the blue and blue/white pair. While a standard ’phone usually has four wires connected to it, only two are used. The same naturally applies to a fax machine connected to a telephone line. But if you wanted to connect, say, computers over a network (standard Ethernet) you would use two pairs, 1/2 and 3/6. Note that you don’t need to separate the individual conductors out to separate wall jacks – you arrange the cable so that the RJ-45 plugs connect to the appropriate terminals inside the jacks. If you want to run two services from the same wall jack, devices called “splitters” (logically enough!) are used. Until now, Cat5 has been used almost exclusively for phone and data. But that’s starting to change, with audio being “piped” around using spare Ensure you have plenty of cable – an extra metre won’t make any difference to performance and the extra can always be pushed back into the wall cavity. Cat5 pairs and lately, we’ve seen that even some video signals have been sent along Cat5. While Cat5 can be used to distribute entertainment-type video/RF signals, so far that hasn’t happened in a big way. By entertainment-type signals we’re talking about TV signals from your antenna and composite video such as that from a video cassette recorder. But “low resolution” video from such things as the cheap CCD security cameras now being sold everywhere (eg, as door viewers, baby minders, pool watchers, etc), well, that is certainly a proposition over Cat5. One of the major difficulties in using Cat5 for high resolution (and for that read high bandwidth) signals is just that: the Cat5 must have the bandwidth required. These days, the better stuff does but you also need a high bandwidth balun to convert the signals from the near-universal 75Ω impedance standard of TV’s, VCR’s etc to the 100Ω impedance of Cat5. And these aren’t the type of devices you’re going to pick up at your local lolly shop. (If you’d like more information on distributing video on Cat5, cable manufacturer Belden have a very good paper on their website – www.belden .com/products/tpvutp85.htm). Not being too adventurous, we decided to stick with tried-and-trusted coax cable. To send entertainment-type video or RF signals over any distance, good quality 75Ω coax cable is needed. RG59 has been commonly used in the past and is quite satisfactory in strong signal areas but for optimum results, a premium coax such as RG6 is preferable. It is double the price but it’s worth it. Naturally, RG59 and RG6 need to be terminated in either “F” or “TV” (ie Belling-Lee) connectors, not RJ45 jacks! We mentioned audio a while ago. We're definitely NOT talking high level (speaker level) hifi. Cat5 cables, even if paralleled, simply don’t have enough copper in them to avoid big I2R losses over any appreciable distance. Background music (ie, low level), perhaps even a pair of speakers on the patio or near the pool might be one thing but running a decent level into hifi speakers over any significant distance is a different thing entirely. In this case, you need to run nice big cables, the bigger the better. (We'd even baulk at running ‘ordinary’ figure-8 over a distance – so-called ‘monster cable’ would be our choice.) The patch panel Front and rear views of the 4-way plates we decided to use in each of the bedrooms. These are standard Clipsal/ HPM plates intended for light switches – the connectors are “snap in” types. 14  Silicon Chip Let’s now go back to the other end of the cable which, as we mentioned before, terminates at a patch panel. What a patch panel does is allow you, via patch cords, to connect anything to anything. If you want a telephone moved from one room to another, simply Note the hinged doors on the modular sockets (we removed one for the pictures) and the protective dust boots over the F-connectors. connect the appropriate patch lead and disconnect the other. If you want to network two computers, simply patch them together (more than two computers on an Ethernet network usually require a hub). Want music out by the pool instead of on the patio? Swap the patch lead from patio to pool. Hopefully, you are now starting to get some idea of the flexibility that structured cabling allows. Assuming of course that the device is correctly wired, when you wire the Cat5 conductors to the appropriate pins on the RJ45 plug the device automatically connects, via its patch cord, to the right terminals. Plug a phone in and it connects to pins 4 and 5 and ignores the rest. Plug a computer in and it connects to pins 1, 2, 3 and 6 and ignores the rest. And so on. The finished data/phone/video wallplate. It is placed about 400mm away from the power outlet with a wall stud separating them – just for extra safety. the least important steps in the overall task. Most important is a plan, drawn out, of what you want and where you want it – both now and in the future. When building new premises, structured cabling is easy – it’s usually just a matter of sending the cable through the same ducts or wall cavities as the other wiring or pipe work to just about everywhere possible! Retrofitting a house is slightly more difficult, especially if access is a problem. As we said before, though, this house had no difficulties in this regard. OK, what did we want? Emanating from the patch panel, the wish list looked something like this: (1) Telephone/fax lines from the patch panel to six locations – all bedrooms, the lounge, kitchen and one in the workshop downstairs. (2) Data lines to network computers in three locations – each of the bedrooms. (3) Speaker lines to two extra locations (not counting the main hifi speakers) – pool area and workshop. (4) Intercom lines between kitchen /lounge and workshop. (5) Security system lines to every room but not necessarily in same locations as other lines . (6) RF (TV antenna) lines (75Ω cable) to all bedrooms and the loungeroom. Going to the patch panel, we needed: Going to Broadway We used a proprietary panel, the KRONE Broadway. It is specifically designed for structured cable wiring in homes. There are other possibilities, of course: KRONE’s MiniLAN, which we looked at last month, is a good example. The main effective difference between the Broadway and the MiniLAN is that the Broadway has RF (coax) distribution capabilities built in, while the MiniLAN is more intended for office applications – but either could be used to do a similar job. Other manufacturers have similar devices – Clipsal, for example, market the “STARSERVE” system (see panel) and doubtless there are others. The plan of attack The actual wiring of the home for structured wiring is arguably one of Using the KRONE “punchdown” tool to connect Cat5 cable to the various connectors. It is quite OK to connect your own LAN and data wiring, along with any other services you are going to run over Cat5. However, it is illegal for anyone but Austel-licenced installers to wire telephone/fax cabling. October 2000  15 (1) Telephone connection – from street – 2 lines – one phone, one fax. (2) Audio (speaker) input – from stereo system (2 pairs). (3) RF input (75Ω cable) from TV antenna on roof. (4) Intercom control unit. (5) Security System control unit. (6) 2 x video camera (baby minder and pool watcher) input, and (7) After all this was done, they decided to get OptusVision on!! Doing it! Now that we knew where we wanted our cables to run it would simply be a matter of determining the shortest distance between point A and point B, running out the cable and fixing it to joists or bearers with cable clamps, right? Well, it’s not quite that simple. For a start, to minimise hum and noise pickup, if at all possible you need to avoid running the cables in close proximity and especially close and parallel to mains wiring. This is less of a problem with shielded coax cable but good practice says you should follow the same rules with coax as you do for Cat5 (which can certainly be affected). So the shortest path may not be the best path – but the shortest practical path is. Where you must cross mains cabling, it should be done at right angles if possible. It’s important for your safety that all cabling, mains, Cat5 and anything else, be properly installed with all insulation intact. When Cat5 needs to turn a corner, it should be on a radius, not a sharp 90° bend. And when terminated to RJ45 jacks, that must be done correctly to minimise NEXT, or “near end crosstalk”. Even stripping back too much outer sheath at a termination point can increase NEXT and threaten the performance of the whole system. NEXT performance is particularly susceptible to conductor untwisting – no more than 13mm should be untwisted in a connection. For this reason, the outer sheath is left intact right up to the point of termination. Cat5 connections are not soldered. Most are made with the aid of a “punchdown” tool. Better versions of this tool strip the wire, push it into the socket, force connection and cut off the excess all in one action. About 600mm of cable should be left at each wall outlet (eg, stuffed back into the cavity) to allow termination and possible later amendment or repair. At the patch terminal end, you should leave double this length on all cables, neatly bundled and laced together, for the same reason. All this information, though, should be known to your licensed Austel installer. If you are not connecting tele-phone wiring (eg, if you are only wiring for a network or audio, etc) you do not need to use an Austel in- staller but you should make yourself conversant with Cat5 wiring requirements and practices first. The Namlea Data Systems catalog is a good place to start! Coax cabling Having finished all the Cat5 wiring and terminating it to its appropriate jacks or blocks, it was then a simple matter to install all the coax cable. We bought a 100m roll of coax, even though we figured we’d need much less. Buying in bulk saves a fair bit of money – and it’s always handy to have some spare cable on hand. (RG6 normally sells for about $1.60 per metre but a hundred meter roll can be bought for under $100, so if you need more than about 60m you’re in front). Like Cat5, coax cable does not take too kindly to very sharp bends – a smooth radius will help avoid any disturbance of the cable which can affect its impedance and performance. The coax cables terminated in “F” connectors, either plugs (which went into their respective sockets in the patch panel) or wall sockets mounted on the same plates as the RJ-45 jacks. These really do require the use of a special crimping tool which, fortunately, my mate had. (Fortunately for me, that is because a good coax cable crimper will set you back about $60 or so). Don’t try to use one of the elcheapo lug crimping tools – it will only ruin your plugs and probably not work anyway. Having punched down or crimped the Cat5 and coax respectively, it was then simply a matter of connecting the cables to their appropriate positions inside the Broadway. On the wall socket ends we bought some F to TV (or “Belling Lee” adaptors and used the standard cables which came with the TVs and VCRs. With 20/20 hindsight, we might have been better to use the TV-type sockets on the wall plates instead of F connectors, which would have saved a few bob in adaptors. Patching it up Another look inside the Broadway, this time showing more clearly the 8-way RF splitter (right side) and the Disconnect Module (bottom of picture) which is where your incoming telephone service lines are terminated. An Austel-licenced person must wire the phone lines but you may wire data and RF services yourself. 16  Silicon Chip Assuming you have wired to plan, now all you need do is patch between the various RJ45 plugs using patch leads. Cat5 patch leads come in a variety of lengths and colours – you should use the same coloured lead as the RJ45 jack to save confusion. While this feature has concentrated on the KRONE Broadway, there is a very attractive alternative from Clipsal. Here is just a broad outline – further details from www.clipsal.com.au Like the Broadway, the Clipsal STARSERVE consists of Cat5 data cable, RG6 video cable, wall outlets and a Central Control Panel. As the STARSERVE Network System is modular, you can increase your Home Office options with the addition of modules that simply plug into the basic system, making it possible to start with a simple system and upgrading it as finance allows. By adding devices to the Central Control Panel, the system can be configured to carry a wide range of video and data services around the home. While the STARSERVE also allows a number of personal computers to be networked, perhaps the most obvious difference between this and the Broadway is that STARSERVE also appears to be designed more with video, security systems and remote control in mind (along with the other “standard” features). Video modulators permit up to eight external sources to be added to the normal television service. Therefore, security cameras, VCRs or laser disks can be connected to the system and viewed on any television in the house. STARSERVE enables you to create a sophisticated video distribution system. Infrared targets, when used in conjunction with RF/IR plates, enable remote control operation of a single TV, VCR or CD from any location.You can watch and control a video located in your lounge room from the bedroom by simply pointing a remote control at the infrared target and the control will travel via the cabling to your VCR or Laser Disk. STARSERVE Features:  Network two or more computers in different rooms to each other or to printers via a hub, just like like in an office.  Have a number of televisions connected to a single video recorder or Pay-TV source, which can be controlled using the remote control from any location in the home.  Have two different telephone or fax lines, each with up to eight outlets around the home or office. Telephone lines can be linked to the security system to provide a call out facility in the event of a break in.  Include security cameras or external video sources into the system, and playback from any TV in your home.  Upgrade the system easily at any time. As STARSERVE is modular, you can start off with a basic system and add components when required in the future. There is some argument as to whether there is any convention about colours of RJ45 jacks/plugs (eg, blue for voice [ie phone] and red for data, etc). Your Austel-licenced installer may be quite adamant about which is used for which – but then again, may not. Probably the best piece of advice we can give is to be consistent – if only for safety and reliability. By the way, we did use that colour code above, with white used for everything else. Just as making an overall plan was necessary to make sure you kept track of what went where, labels on patch panel jacks are a must. Also, if you didn’t see our article last month, there is a big difference between Cat5 cable for permanent installation (eg, in the wall) and Cat5 for patch leads. The first, normally called LAN Cat5, has a single solid conductor while patch Cat5 leads have multiple, flexible conductors. The modular plugs and jacks which attach to these must be the right ones for that type of cable (ie, you cannot use modular plugs designed for LAN Cat5 on Patch Cat5 and vice versa). By the way, patch Cat5 cables also require a special crimper for their plugs. You are much better off buying pre-made patch leads or having someone make them for you if you need non-standard lengths. Your patch panel will almost certainly come with some patch leads. Just as certainly, there won’t be enough – or they will be the wrong colours for the services you want to patch! Change your mind? Now that the system is installed, if you change your mind about what goes where, it’s simply a matter of changing a patch lead, not re-routing a cable. All you do is unplug the patch lead from its front panel socket and plug it into where you want it to go. It’s that simple! About now is when you discover how valuable those little labels are alongside each of the RJ-45 jacks or “F” connectors. In a year or so you won’t remember which cable went to where without a label! And should you decide in the future you want different services to run in the Cat5 you’ve installed, that’s easy too – without massive re-cabling. SC For more information: KRONE: PO Box 335, Wyong NSW 2259. Phone (02) 4388 2259, website www.krone.com.au NDS: (Namlea Data Systems) 4/11 Orion Rd, Lane Cove NSW 2066. Phone 9429 0800, website www.namlea.com.au CLIPSAL: (Gerard Industries Pty Ltd) PO Box 103, Hindmarsh SA 5007. Phone (08) 8269 0511, website www.clipsal.com.au October 2000  17 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 Jam along with your favourite CD with the: Want to play your guitar in accompaniment to your fa­vourite CDs? Want to do it without disturbing anyone? Then build the Guitar Jammer, a neat little headphone amplifier with mixing facilities for guitar and CD inputs. It sounds great and won’t cost a bomb. Guitar Jammer By LEO SIMPSON & PETER SMITH O K, WE KNOW THAT most guitar amplifiers have a headphone socket that you can use for a quiet practice session at night but who wants to have to switch on a hulking big amplifier just to listen to headphones? Also playing guitar via the headphone socket on many amplifiers is not that great. Often there is quite a lot of hum and buzz and it often doesn’t sound particularly clean either. Nor do guitar amplifiers perform all that well with the high level signals from a CD player. So we have come up with a low cost and compact headphone amplifier with mixing for the signals from a guitar and a CD player. For economy the headphone drive is mono, from a single LM386 IC amplifier. It can be pow­ered from a 9V DC plugpack or a 9V battery. Either way, the sound quality is surprisingly 22  Silicon Chip good considering the simplicity of the circuit and it is certainly better than the sound from the head­phone socket of most guitar amplifiers. Performance Power Output 120mW into 8Ω headphones Frequency response -3dB at 30Hz and 70kHz Total Harmonic Distortion Typically less than 0.2% (see graph) Signal-to-Noise Ratio 71dB unweighted (20Hz to 20kHz) with respect to full output; 76dB A-weighted under the same conditions Input sensitivity Guitar input 45mV; CD input 550mV Actually, the idea is not new. We picked up the idea from an article on a “Guitar Jammer” in the July 1998 issue of “Popu­lar Electronics”. This was also based on an LM386 but we have refined the circuit in a few aspects and produced a new PC board with all the components, including the pots and jack sockets, on the board. The circuit is also similar to a headphone guitar amplifier we published in the May 1995 issue but that circuit did not include mixing facilities. Input facilities The Guitar Jammer is housed in a compact plastic box and has two potentiometers for setting the input levels for the CD player and guitar. It has two 3.5mm stereo jack sockets, one from the CD inputs and the other for the headphone output. The 6.5mm Fig.1: based on an LM386 power amplifier IC, the circuit has mixing facilities for a guitar (or other electronic musical instrument) and both channels from a CD player. jack socket is for the guitar lead. The circuit will drive virtu­ally any stereo headphones, whether they are 400Ω, 32Ω or 8Ω, although the best bass will come from headphones with full ear-enclosing muffs. Now let’s have a look at the circuit of Fig.1. It shows a stereo input socket (CON2) for the CD left and right channel inputs. These are mixed together and reduced in level via sepa­ rate 220kΩ resistors and fed to VR1, a 10kΩ logarithmic poten­tiometer. The guitar input (CON3) is coupled via a 100Ω resistor and .0039µF shunt capacitor to VR2, a 50kΩ logarithmic potentiom­eter. The signals from the wipers of VR1 and VR2 are then mixed together with 10kΩ resistors and fed via a 0.22µF capacitor to pin 3 of IC1, the LM386 power amplifier. The inverting input, pin 2, is grounded via a 0.1µF capacitor. The AC gain of the amplifier is set to 33 by the 220Ω resistor between pins 1 & 8, while the 22µF capacitor ensures that the DC gain is zero. The amplifier is biased so that the voltage at pin 5 sits at half the supply voltage, for maximum output swing. A DC blocking capacitor of 470µF is used to couple the output signal to the headphone socket. This socket is wired so that both channels of the headphones are connected in parallel and this gives a nominal load of 4Ω, if 8Ω headphones are used. However, 4Ω is not an optimum load for the LM386 as it results in higher distortion. Hence, the headphone socket is connected in series with a 10Ω resistor to give a nominal load of 14Ω. We are not worried about the power loss in the 10Ω resistor because the signal level to the headphones is more than adequate. The 470µF capacitor rolls off signals below 24Hz, assuming 8Ω headphones are in use. For higher impedance headphones the rolloff will be at a much lower frequency. We have specified a 9V DC plugpack as one of the power supply options so we have included a 47µF capacitor There are relatively few parts, so the PC board should only take a few minutes to assemble. Make sure that the polarised parts are installed correctly. October 2000  23 at pin 7. This improves the power supply ripple rejection of the circuit while a 470µF capacitor on the 9V supply provides extra filtering. A Zobel network consisting of a .047µF capacitor and 10Ω resistor is included at the output to ensure high frequency stability. As already noted, the power can come from a 9V DC plugpack or a 9V battery although the 9V battery will not last long. By the way, don’t be tempted to use a 12V DC plugpack because its unloaded DC output of around 17V or higher will probably blow the LM386. As it is, a typical 9V DC plugpack is likely to deliver close to 12V. Diode D1 is included to provide reverse polarity protection for the circuit. Construction All of the components, including the two pots and the vari­ous sockets, are mounted on the PC board which measures 63 x 106mm (code No. 01110001). It is designed to be a snug fit in a standard plastic case measuring 130mm x 67mm x 44mm (Jaycar HB6023). The component layout diagram is shown in Fig.2. The suggested order of assembly is as follows. First, mount the toggle switch S1, the three jack sockets and the two pots on one side of the board. Then mount the DC socket but before you do, make sure that it matches the plug on the DC plugpack. There is nothing quite so frustrating as trying to connect DC power when the plug and socket don’t match! Fig.2: this is the component layout for the PC board. Note that JP1 is not used; just wire in the link. Table 1: Capacitor Codes      The bodies of the two pots are earthed by connecting them to the PC board using tinned copper wire. Note the mounting details for LED1 (see text). Value IEC Code EIA Code 0.22µF   220n   224 0.1µF   100n   104 .047µF   47n  473 .0039µF   3n9  392 Table 2: Resistor Colour Codes  No.   2   2   1   1   1   2 24  Silicon Chip Value 220kΩ 10kΩ 2.7kΩ 220Ω 100Ω 10Ω 4-Band Code (1%) red red yellow brown brown black orange brown red violet red brown red red brown brown brown black brown brown brown black black brown 5-Band Code (1%) red red black orange brown brown black black red brown red violet black brown brown red red black black brown brown black black black brown brown black black gold brown If you are going to use a DC plug­ pack, you don’t have to install the 9V battery snap connector. Alternatively, you can install both the battery connector and the DC socket, since the DC socket automatically disconnects the battery when the plugpack is plugged in. Note that the two pots must have their shafts cut to suit the knobs; ie, about 10cm long, Make sure that both pots have a milled flat on their shafts so that the push-on knobs will fit properly. When installed on the PC board, the bodies of the pots must be earthed to the copper pattern. Solder a short length of the tinned copper wire to the body of each pot; you may need to scrape away the plating on the body to do this. Then solder both wires to the board, via the hole between the two pots. Next, fit the diode and the resistors, followed by the capacitors. The diode and electrolytic capacitors must be con­nected in the right way around otherwise the circuit won’t work and damage may occur. Note that the LED needs to be stood off the board on two stiff lengths of tinned copper wire and then bent over so that it will poke through the side of the case (see photo). Finally, the LM386 can be installed, making sure that it goes in the correct way – see Fig.2. If you look at Fig.2, you will notice that there is provi­sion for JP1 (near the CD input) but this is not fitted. Instead, fit a short link between points 1 & 2. Drilling the case We’re rather proud of the mounting arrangement of the PC board in the Fig.3: use this diagram as a template when drilling the case. case. The board is just wide enough to sit upside down on the integral board slots inside the case. Then, when the lid is fitted, the lid becomes the base and the rubber bungs which fit in the screw holes become the feet for the case. All that means that the case must be drilled exactly as shown in the diagram of Fig.3. Also, on the side with most of the holes drilled, the lower section of the integral board slots must be removed with a sharp chisel. This will allow the pots and input sockets to sit close to the side of the case. Note that there is one hole on the opposite side of the case to take the DC input socket. When you fit the board into the case you will need to slightly pull one side of the case out to allow the DC socket to pop into place. On the other hand, if you are not using a battery and do not have the DC socket fitted, you will not need to drill a hole for it and the board will slip easily into place, to be retained by the lid when it is fitted. Before you fit the board into the case, do a voltage check. Apply power and check that 9V (or thereabouts, depending on your DC plugpack) is The board sits on top of integral slots inside the case and secured by the lid and by fitting nuts to the pots and headphone socket. The inset picture shows how the lower sections of the board slots on one side of the case are removed. October 2000  25 Parts List Fig.4: this graph shows the power output versus harmonic distor­tion at 1kHz when 8Ω headphones are connected. 1 PC board, code 01110001, 63mm x 106mm 1 130mm x 67mm x 44mm plastic case (Jaycar HB-6023) 1 SPDT miniature toggle switch, PC mount (Altronics S-1320) 2 20mm knobs (Jaycar HK-7711) 1 9V battery connector 1 2.5mm PC mount DC jack socket (CON1; Jaycar PS0520) 1 6.5mm mono switched PC mount jack socket (CON3; Jaycar PS-0160) 2 3.5mm stereo switched PC mount jack socket (CON2, CON4; Jaycar PS-0133) 2 PC stakes 1 16mm PC mount 10kΩ log pot (VR1) (Jaycar RP-7610) 1 16mm PC mount 50k log pot (VR2) (Jaycar RP-7616) Semiconductors 1 LM386N-1 audio amplifier (IC1) 1 1N4001 1A 100V diode (D1) 1 5mm high brightness red LED (LED1) (Jaycar ZD-1792) Resistors (0.25W, 1%) 2 220kΩ 1 220Ω 2 10kΩ 1 100Ω 1 2.7kΩ 2 10Ω Fig.5: this is the full-size etching pattern for the PC board. Capacitors 1 470µF 25VW PC electrolytic 1 470µF 16VW PC electrolytic 1 47µF 16VW PC electrolytic 1 22µF 16VW PC electrolytic 1 0.22µF MKT polyester 1 0.1µF 50VW MKT polyester 1 .047µF MKT polyester 1 .0039µF MKT polyester Miscellaneous 9V battery or 9V DC 150mA plugpack, small cable tie, 15cm 22AWG (0.71mm) tinned copper wire, solder, etc Fig.6 actual size artwork for the control panel which goes on the bottom of the case. 26  Silicon Chip present at pin 6 of the LM386. Half this figure should be present at pin 5 and the LED should be alight. OK? Then go ahead and fit the board into the case, fit the label to the bottom of the case, screw on the lid on and you’re ready to play. Note that a kit for this project will be available shortly after this issue SC goes on sale. ATENTION TEACHERS AND EDUCATION INSTITUTIONS A GREAT CHANCE TO BY SCHOOL EQUIPMENT AT BARGAIN PRICES SCIENTIFIC CALCULATOR CASIO FX-39, old model calculator with a bright green 8 digit Fluorescent display!, works from 2 AA batteries, good quantity: $18 SCIENTIFIC CALCULATOR CASIO FX-D400, 16 digit, dot matrix LCD displays alpha characters along with values and indicators, has replay function, large quantity: $26 DIARY - ORGANIZER CASIO JD-5000BK “My Magic Diary", displays messages in one of 5 languages, English / Italian / Spanish / German / French. Modes of operation include include Telphone Directory, Schedule, Calendar, Data Memo "Diary", Secret Memory area, Time keeping, Alarm, Fortune Telling, Conversion, Calculator, Data Communication. Has an easy to understand main menu with simple icons, good quantity: $20 SCIENTIFIC CALCULATOR CASIO FX-350D, 8+2 digits, huge quantity: $15Ea., buy 10 or more for $13.50 Ea. MORE CALCULATORS ON OUR WEB SITE STEREOSCOPIC MICROSCOPE These scopes are used but still in excellent condition as the come in their own wooden storage / carry case. Would be ideal for surface mount PCB inspection etc. Just a fraction of their new cost. MONOSCOPIC MICROSCOPE These are also used come in their own case and in excellent condition. With 2 objective lenses, Focusable light source / mirror and vernier adjustments. MORE DETAILS ON OUR WEB SITE $220 $220 NEW GEARED AC MOTORS Small mains operated geared motors, very strong, made for rotating microwave turntables, 240V/ 50Hz/ 3W/ 5RPM., $4Ea. or or 4 for $12. BRAND NEW GERMAN MADE MOTOR AND GEARBOX. 24V motor but runs well with plenty of torque at 12V & starts at 23V. 10mm shaft, the motor is 60 X 94mm. We think it is a truck windscreen wiper motors. worth over $100, But as a special only... just $20 20ADC motor speed controller kit (K98) $14 when purchased with the above motor. 12v-24v inverter under development see our web site for speed controllers & motors SUPER MICRO MONOCHROME CCD CAMERA MODULE: 9 to 14.5V DC (1.2W) Output: CCIR (50Hz, 625 lines interlaced) composite video (1V pp 75ohm). Horizontal res: 380 TV lines, 1/3" CCD, If you mention “IBM” when ordering. Sensitivity: 0.2Lux. Auto-Iris. This camera is Infra Red IBM VOICE TYPE 3.0 KIT: responsive & can be used in total This is a complete kit for darkness with IR Illumination. 23 X 60mm , Voice Dictation. Incs. available 20grams. Inc. 3.7mm lens: (AR717R) $99 software, manual & a separately noise cancelling desktop H I G H P E R F O R M A N C E microphone. Brand new . MONOCHROME CCD CAMERA Software incs. VoiceType MODULE: 7.5 to 14.5V DC (1.16W), IBM Anti Virus & Jungle Output CCIR (50Hz, 625 lines interlaced) Book for Windows on CD.(IBMVT3) $16 Composite video (1Vpp 75ohm). Res. is MERIT PENTIUM II MOTHERBOARD: 380 TV lines, 1/3” CCD, Sensitivity 0.1 Recent motherboard made for the latest Lux, Auto-Iris. This camera CPU's. Std ATX form factor. Has 3 x (16- is Infra Red responsive & bit) ISA slot, 4 x (32-bit) PCI slots, 1 x AGP can be used in total slot & 3 x DIMM (memory) slots, On-board darkness with IR Illum1 x PS/2 keyboard, 1 x PS/2 mouse socket, ination. 32mm squ. 2 x USB, 1 x parallel, 2 x serial ports. With x 27mm. 20grams. setup manual & CD, IDE & FDD cables. 3.7mm lens: (AR732) $89 Brand new in original box. Accepts Intel COLOUR CCD CAMERA MODULE Pentium II & Intel Celeron CPU's (NOT WITH AUDIO: 12V DC (2W), PAL (50Hz, SUPPLIED) from 233 to 800MHz. The 625 lines interlaced) composite video (1V CPU socket is SLOT-1, S-370 CPU could pp 75ohm). Res. 330 TV be use with a converter board (NOT lines, 1/3” CCD sensitivity SUPPLIED). Selectable 66 & 100MHz 3Lux. Has Auto-Iris. BUS speeds & a clock multiplier up 38mm Squ. x 32mm to 8 times. Should high & unit weighs accept Pentium 20 grams. Inc. 3.7mm III CPU's, on a lens: (ARCB21) $180 100MHz bus: H OUSED MONOCHROME CCD (M6TBA) $90 CAMERA: 12V DC (1.16W) Output: CCIR PENTIUM MOTHERBOARD: (50Hz, 625 lines interlaced) composite Std. AT form factor, with VIA Apollo MVP4 video (1V pp 75ohm). Res. 380 TV lines, chipset. ZIF Socket 7 for Intel Pentium (std 1/3" CCD, Sensitivity: 0.1Lux. Auto& MMX) CPUs, 100 to 233Mhz, IBM / Cyrix Iris. This camera is 6x86/6x86L/6x86MX/M-II 150 to 400MHz, Infra Red responsive AMD K5/K6/K6-2/K6-III 133 to 450MHz & & can be used in total IDT Winchip C6 CPUs 200 to 225MHz. darkness with IR Has onboard AC97 Audio & Video. 2 x Illumination. 40 x 39 x DIMM sockets, 1 x (16-bit) ISA slot, 1 x 35mm high & unit AMR (audio modem riser) slot & 3 x (32-bit) weighs 13g (AR830M) $99 PCI slots. On-board IO incs. 2 x PCI IDE ports, 1 x PS/2 mouse, 1 x DIN keyboard MONOCHROME CCD VIDEO CAMERA: connector, 4 x USB Ports, 1 x Parallel, 2 x B&W Camera built on a PCB with auto iris. Serial and 1 x VGA connector. New with (IR) responsive. (0.1 lux) Can be used in manual, setup CD, IDE / FDD cables & 4 total darkness with IR Illumination. 32 x 32 back panel connectors for printer & serial by 27mm. Output is std video & can be plugged into the "VIDEO IN" socket of any ports, VGA monitor, Australian std VCR, video monitor or TV, joystick & 3 audio or via an RF Modulator to an Ant. Input. connectors In orig. Can be focused sharply down to a few anti-static bag. mm(useful for people with visual 22cm x 19cm: impairment). Spec.: Power req.: 10V to (EPMVP4) $90 12V <at> approx. 50mA. Res: 400 lines NEED A CPU FOR ONE OF THE ABOVE approx. CCD: 1/3" (320 000 pixels). MOTHERBOARDS... THEN CALL 30grams: with 60° (Pin Hole) lens fitted: BRANKO FOR OUR LATEST PRICES (CA41L60) AND AVAILABILITY $89, with 92° lens: (CA41L92) $89, with OVERHEAD PROJECTOR 120° lens:(CA41L120) LENS ASSY. $89, with 150° (Fish Amazingly powerful lenses Eye lens) (CA41L150) and front surface mirror $99 assembly.$18 VIDEO ACCESSARIES FREE FREE FREE DICTATION SOFTWARE WITH THE PURCHASE OF ANY OF THESE MOTHERBOARDS KTX PENTIUM II HEATSINK & FAN: Brand new in original pack with clips & power lead terminated with a 3 pin plug. (HHSP2) $4.50 Others available. Check our web site EAGLE A486 MKII MOTHERBOARD: NEW Std AT motherboard. ZIF Socket 3 supports various Intel 486 CPU's. This board is fitted with an AMD Am5x86 P75 CPU (Part # AMD-X5-133ADZ). The 3.45V CPU & requires a fan & heat-sink. Some have fan & heatsink. 2 x 72pin SIMM sockets, 4 x (16-bit) ISA slot & 3 x (32-bit) PCI slots. IO includes 2 x IDE ports, 1 x FDD port, 1 x DIN keyboard, 1 x Parallel & 2 x Serial. In original anti-static bag. 22 x 18cm: (GMB4) $65 ea. (42 only) FLIGHT FORCE PC JOYSTICK: This analogue joystick features 4 fire buttons - with disable function for 2 player compatibility, Contoured handgrip, auto centering, independent auto-fire & X & Y axis trim. Has a durable metal base with a large suction cup for stability. This item is new & in its original retail box: (ZA0098) $25 USED INSULATION BREAKDOWN VOLTAGE "MEGGER" TESTER This is a high quality hand cranked unit mounted in its own timber case. Includes bridge and also Murray loop functions. Over 500V open circuit. 450V into 1Mohm. In goo condition. $80 M U LT I F U N C T I O N B AT T E R Y CHARGER DISCHARGER New in original Box with instructions. Designed to charge mobile batteries 4.8V, 6.0V & 7.2 & operate from 12-24V input. By changing the value of 1resistor it can charge higher voltages. Features inc. processor control & multi stage charge indicator. Inc. Cig. lighter lead & instructions for modification for higher voltages & 12V 1A plug pack ( higher voltage plug pack . required for 9.4 volts or higher). SMOKED ACRYLIC SHEET (NEW) (PERSPEX TM) Ideal for LED displays etc. It makes LED displays more visible . 425mm X 260mm: 6 sheets for $15 425mm X 130mm: 6 sheets for $7.50 Coverer with protective paper 250W LAMP, LENS & REFLECTOR ASSEMBLY Part of a over projector. Includes lamp, reflector lens LIKE IR ILLUMINATORS (several sizes) and 10 Amp trans former. TELEPHONY COMBO 28.8K MODEM / VIDEO SWITCHERS (switch up to 4 Limited quantity: $22 SOUND CARD: Kit inc. ISA card, manual, cameras), VCR CONTROLLERS (record Driver Disks, phone movement for security), & MORE We have to much test equipment on our Cable and a Headset shelves we need to clear to make way for CAMERAS ON OUR WEB SITE with speakers and more. Check out our web site Great Microphone. Brand A V O U N I V E R S A L - M E T E R bargains at a fraction of the new cost. If it’s new:(MDSP2780) (MULTIMETER) Used In good condition not on our web site then ring us. stocks $25 (70 only) This high quality item is change daily!!! CHECK OUT MORE GREAT COMPUTER in it's own carry case & is NEW GIANT CAPACITORS in original BARGAINS ON OUR WEB-SITE in as new condition. inc. packing.5uF 8000 volts. leads, Instruction Inc. ceramic insulated GIANT FRESNEL LENS manual & test certificate terminals & threaded APPROX. 350mm X ranges inc....Dc 5uA to connections with nuts. 3mm. GREAT FOR 10A, 3V to 3000V... Aprox. 300 X 110 X LOTS OF FUN Ac 100mA to 10A, 230mm.USA Made by EXPERIMENTS LIKE 3V to 3000V... Condenser Products SOLAR FURNACES Plus 3 ohms ranges:$80 25 only approx 7Kg $80 etc. JUST $25 www.oatleyelectronics.com Orders: Ph ( 02 ) 9584 3563 or 64, Fax 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 October 2000  27 major cards with ph. & fax orders, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 SC_OCT_00 B efore we start, we should perhaps emphasise that there is no way that you could rely on a simple breath tester such as this to determine if you’re fit to drive (or operate machinery, etc). While it will give you an indication that you are at or over “oh-five”, it could just as easily be reading slightly under when the boys in blue say you’re slightly over. So be warned – this is not a legal instrument and makes no pretence to be one. Then again, what do you expect for less than $30? (The “real” units cost many hundreds, even thousands of dollars!) Also, you may not realise that when you’re asked to provide a By Ross Tester roadside breath test, even those (no relation to Breath Tester) testers are only supplying a relative reading. If this reading is between the alcohol in your blood“over the limit” you will be destream and the alcohol in your breath tained for testing on one of the larger, but there are reasons why it could be very accurately calibrated machines. different. Only at this stage do the Police obtain (A quick tip: it’s often higher in the a blood alcohol level reading which bloodstream than on the breath, so if will stand up in court. you’re determined to demand your Even then, you usually have the “rights” you could end up in even right to demand a blood test to deterdeeper doggie doo-dah!). mine the actual blood alcohol content By the way, just in case you’re (or BAC) because that’s what you are thinking “gee, I wonder if all this is actually charged with. from experience” the answer (touch There is a very close correlation 28  Silicon Chip wood) is no. But I am the proud owner of a “responsible service of alcohol” course certificate. So there! Our breath tester Now we’ve covered the legalities, let’s get on with the project. It’s built into a disposals case and has an alcohol sensor at one end, into which you blow. This detects the amount of alcohol on your breath and registers it on a series of LEDs, the more LEDs alight, the more alcohol you’ve consumed. It is powered by 12V DC, for example, from a car cigarette lighter (a suitable lead & plug is supplied in the kit). As such, it could be left in the car – but once again, please don’t rely on it!!! The circuit is by no means new – it’s been around for perhaps twenty years. In that time there have been significant advances in the alcohol sensor, which forms the heart of the unit. The display side is based on an old friend, the LM3914 LED driver. The sensor A high quality, thick film semiconductor gas sensor is used to detect the presence of alcohol on the breath. There are many different types of gas sensors – some detect the presence of the various “fuel” hydrocarbons such as propane, octane, etc and are used extensively in bilge alarms for boats. The sensor used in this project, It might not quite stand up in court but this simple little breath tester can give a quite reasonable indication of your soberity sobrity sob how much you’ve had to drunk. It’s easy to build – and fun to calibrate! though, is made to detect alcohol – specifically ethyl alcohol. In the presence of gaseous alcohol, its resistance decreases dramatically, in direct proportion to the amount of alcohol detected. It is this feature which makes it ideal for our project. Incidentally, while each sensor is made to detect a certain type of gas there is almost always some sensitivity to other hydrocarbons, so the reading may be quite erroneous if there are other gases about. As you might imagine, the sensor is extremely sensitive. It must detect the presence of alcohol at better than one part in 5000 (.05%). Not only that, the sensor needs to be free of any contamination – even lying around not even turned on it can be affected by other gases. For this reason, the sensor has an inbuilt heating element which “purges” the sensor unit itself so the readings are of the gases detected at that time and not before. The relatively heavy current drawn by the heater (125mA) means that battery operation of this unit is not really a proposition. Yes, it could be done but you’d be always changing or charging batteries. So we have a sensor which has an element (actually two elements) October 2000  29 Fig.1: the circuit could hardly be much simpler! A semiconductor sensor changes resistance in the presence of alcohol, varying the voltage at pin 5 of IC3. This in turn lights the appropriate LED(s) to indicate the amount of alcohol. which change resistance in the presence of alcohol. Now all we need to do is detect that change and display it. Detector/display As we mentioned before, the display uses the LM3914 LED driver, a device we have often used in such things as audio level meters, fuel mixture meters and similar projects which require a LED “bargraph” display. This IC is designed to have a LED connected to each of its ten output terminals and will progressively light the LEDs according to the voltage at its input (pin 5). If the voltage is low none or few light but as the voltage increases, more and more LEDs will light up. (This of course assumes we are using the LM3914 in its “bargraph” mode (ie, it lights all LEDs in a column from the minimum up to the LED indicating the reading). It can also be used in “dot” mode by leaving out the link – only the LED indicating the reading is lit in this mode. We use a selection of green, orange and red LEDs to simulate OK, borderline and not OK alcohol levels. Ideally, the orange LED, or perhaps the transition between the last green and the orange should occur at the 0.05% alcohol level. 30  Silicon Chip The range of voltages over which the LM3914 responds is set by the ratio of resistors connected between pins 7 and 8, and 8 and ground. These are set up to match the output levels of the sensor. Back to that input, pin 5. As you can see, it is connected directly to one of the elements of the sensor, pins 4 and 6, with a resistor and pot connected to earth. The other element, pins 1 and 3, Parts List 1 Breath Tester PC Board* 1 Plastic Case* 1 Cigarette-lighter plug & lead* Semiconductors 1 alcohol sensor (IC1) 1 LM7805 5V regulator (IC2) 1 LM3914 LED Driver IC (IC3) 5 3mm green LEDs (LED 1-5) 4 3mm red LEDs (LED 7-10) 1 3mm orange LED (LED 6) Capacitors 1 100µF 25VW PC electrolytic 1 10µF 16VW PC electrolytic Resistors (0.5W, 5%) 1 1.8kΩ (brown-grey-red-gold) 1 2.7kΩ (red-violet-red-gold) 1 3.9kΩ (orange-white-red-gold) 1 10kΩ PC-mounting trimpot * see text is connected to the +5V supply from the 7805 5V regulator. Remember that the resistance between the elements is variable. This then forms a “voltage divider” across the 5V supply. Normally (ie, no alcohol detected) the sensor resistance is high, so the voltage at pin 5 will be low. But when it detects alcohol the sensor resistance drops, so the voltage at pin 5 will be high. The actual voltage is in direct inverse proportion to the sensor element’s resistance, which itself varies in direct inverse proportion to the amount of alcohol detected. The 1.8kΩ resistor and 20kΩ pot are used to calibrate the circuit – we set the LED display so that the orange LED lights when 0.05% alcohol is detected. We’ll look at calibration shortly. The 100µF and 10µF capacitors on the input and output of the 7805 regulator help to smooth out any variations in the supply and also to remove any noise on the supply line, both of which could affect the accuracy and/or readings. Building it All components, including the gas sensor, mount on a single PC board. There are only a few components to solder in place but as usual, it is wise to start with the lowest profile Fig.2 (above) is the component overlay. At right, reproduced same size, is the completed PC board connected to a section of the PC board from the disposals case. The only reason for using this board is to take advantage of its 2.5mm DC socket. Note there is an error in the PC board overlay – the green LEDs go to the left and the red to the right. ones (ie, the resistors and trimpot) first. Next move on to the capacitors, the regulator and the IC socket. All of these must be soldered in the right way around or your circuit will not work. Also, the regulator pins must be bent down 90° so that it lies parallel with the PC board. A hole is provided for securing the regulator to the PC board but this is not really necessary. You need to decide whether you want a bargraph display or a dot display. If you want a bargraph, use one of the component lead off-cuts to solder a link onto the PC board where shown. If you want a dot display, don’t solder the link in. When you come to solder the sensor in, you will note that there is nothing to tell you which way around it should go – the six pins fit in the holes two different ways. While we said before that this was a semiconductor device (and therefore you might expect it to be polarised) this particular semiconductor can go either w­ay around. The sensor is meant to mount high off the PC board – poke only enough legs through as you need to for reliable solder joints. The last components to be soldered in are the LEDs and we have left these until last because these need special treatment. They need to be lined up in both the vertical and horizontal planes. Before poking them through their holes, though, a warning: some PC boards may have the screened printing (on the component side) wrong as it applies to the LED positions. Holding the board so its label (K080B Breath Tester) is at the bottom, the RED LEDs go on the left and the GREEN LEDs go on the right. The orange, of course, is between them. The symbols for the LEDs show a flattened side (the anode) all facing the same way. Make sure you put the LEDs in this way around or they won’t work! Now, how do you line them all up? Simple: holding the LEDs so they won’t fall out, turn the PC board over and support it long its edges on two books or blocks about 25mm thick. The LEDs will all drop down to the bench below and be exactly the same height. Solder just one of each LED’s legs in while the board is supported like this (it doesn’t matter whether you solder anode or cathode). Then turn the board over and check the horizontal alignment – if necessary, push the LEDs until A close-up view of the PC board end-on, showing how the alcohol sensor mounts up in the air (as do the LEDs behind). The reason for this is so both poke through the front of the case when assembled. October 2000  31 300mA and up would be fine) go right ahead. The regulator will cure any of the ills (hum, noise, etc) from the plugpack. Just make sure you get + to + and – to – or you will probably do some damage! The case You’ll need to drill 11 holes in the case – a 17mm diameter hole for the alcohol sensor (top) and 10 3mm holes for the row of LEDs, seen here just above the label. they are all lined up perfectly and equally spaced. Then turn the board over again and solder in the other leg and clip all the excess legs off. Apart from the power lead, your Breath Tester PC board is finished. Power In the kit there is a car cigarette-lighter lead. Its plug has a LED to show you power is applied and inside the plug is a 3A fuse (accessed by unscrewing the plug tip). On the other end is a moulded 2.5mm DC line plug. You can attach power in one of two ways – sacrifice the plug and solder the lead directly to the PC board; or connect it via the PC board which comes with the surplus case. This board has a 2.5mm DC socket so it’s simply a matter of plugging in. We’ll look at the second option in a moment. If you want to solder the lead direct to the board, cut the cable as close as you can to the plug (it’s only a 600mm cable so you haven’t got a lot to play with). Strip back 10mm of outer insulation to reveal the twin cables inside. Now here’s a trap for young players: the white wire is connected to the centre pin of the cigarette lighter plug which, of course, makes it the positive. That means the red wire is the negative! Yes, red is negative. Don’t say you weren’t warned! Strip 5mm of insulation off each of these and solder each to their appropriate points on the PC board. Of course, there’s nothing in the good book which says you MUST run this project from a cigarette lighter. If you want to run it from a DC plugpack (anything from 7-12V or so at about 32  Silicon Chip The Breath Tester is assembled in a surplus case which used to hold a mobile phone in a car. It fits quite nicely and requires only a little surgery, mainly to expose the sensor unit itself. First, though, we’ll look at power. We mentioned another PC board a moment ago. With a little ingenuity and thought (or is that thought and ingenuity?) you can cut this board so that it still fits in the bottom of the case, with its 3.5mm DC socket intact. That way you can simply plug the cigarette lighter lead in without cutting the plug off. The main Breath Tester PC board can then occupy the rest of the case, as our photographs show. Of course, you will have to solder a couple of wires (insulated hookup wire) from suitable tracks on the cut-off PC board to the Breath Tester PC board but this shouldn’t prove difficult. You don’t need to connect power –simply plug the DC plug (on the cigarette lighter lead) into the DC socket and with your multimeter on an “Ohms” or “continuity” range, find the points on the board that show zero Here’s how it all fits together inside the disposals case (which was once a car adaptor for a mobile phone). No screws are used to hold the boards in place –they simply drop over the mounting posts and are held tight. ohms (or close to it) between the tip of the cigarette lighter plug (the “+” connection) and the springy metal bits on its side (the “–” connection). Connect these points via short lengths of suitably coloured insulated hookup wire to the + and – power connection points on the Breath Tester PC board. Now, about that surgery we mentioned. The alcohol sensor needs to have a good airflow around it to detect properly. For this reason, the end must poke through a 17mm diameter hole in the case. This hole is drilled where the speaker used to go in the disposals case – right in the middle of the holes which let the sound out. In fact, the extra holes around the sensor are useful in increasing air (gas) flow. The other holes required are of course for the 10 LEDs – not much point in having them flash merrily away inside the case, is there? The holes for the LEDs should be 3mm in diameter, spaced 5mm apart. Only the tips need to emerge through the holes. These holes are drilled in a straight line across the front of the case, exactly 45mm down from the middle of the sensor hole, as shown in the photo. In the kit, a printed label is supplied. This fits perfectly in the “well” in the disposals case and can be glued into position after being cut to shape and size. However, it will need to be protected with some clear self-ad- What we are aiming to do is set the Breath Tester up so the orange LED comes on at 0.05% BAC. Start by adjusting the calibration pot so that the lowest LED just comes on. Now, according to that Responsible Service of Alcohol course I was telling you about before, 0.05 corresponds to 3 standard drinks in one hour (or less). Unfortunately, there is no easy way (at least for the lay person) to calibrate to this standard so, with much regret, we’re going to have to ask you to drink 3 middies (or 15oz/385ml glasses) of full strength beer during the next hour. We can only apologise for putting you through this but we haven’t been able to think of any other way. Honestly, we wouldn’t ask you to do this if it wasn’t absolutely necessary in the interest of global peace and Fig.3: full-size artwork for the Breath harmony and the closer alignment of Tester PC board, viewed from the the galaxies. Just make sure the beers copper track side. Use this pattern to check your PC board for any defects (eg, are nice and cold! bridges). If beer is not to your liking, you can substitute a nip of spirits or a 200ml hesive contact film or other suitable glass of wine as a “standard drink”. material. We’ve got to warn you, though, Construction is now complete – all that wine varies all over the shop in that remains is calibration. its alcohol content so could be less First of all, though, you need to accurate. (Full strength beer is not so apply power for at least an hour, variable). preferably several hours, to allow the And just as importantly, this methheater to completely purge the sensor od does not take into account differof any gas residue it has picked up ences between males and females nor since being manufactured. metabolic rates, bulk, whether you’ve (A long purge is normally only eaten food, etc – all of which make required for a new unit. Later purges a significant difference to a person’s will be done much more quickly – just apparent sobriety. a few minutes is usually tons of time). How are those drinks going? The When you apply power, turn the first one didn’t even touch the sides calibration pot to both extremes of and you’re into the second already? its travel. One way you should see Hey, slow down a bit: you have to be all the LEDs come on (or the top LED of sound mind to calibrate this thing. in dot mode). If one or some of the OK, so we’re too late. Call in a mate LEDs don’t light, the odds are about and make sure he doesn’t touch a drop 100:1 on that you have it or them in till it’s done. back-to-front. Come to think of it, that’s a good Perhaps the easiest way to check move. Once calibrated he can have that it is working is to open a bottle three standard drinks and see what of metho and waft the fumes over the his reading is! sensor. Metho is almost pure alcohol Ready? Good. You’ll need to wait, so you should get an instant response! say, 15-20 minutes after your last drink to make sure it’s well and truly Calibration in your system. If you’re younger than 18 years, you Blow into the sensor and see if any must not read the following section. more of the LEDs light. You may need Avert your eyes immediately lest a fate to do this several times, adjusting the worse than death befall ye. calibration pot a little each time. Are they gone? Great. We couldn’t You should be able to get it to the get into the serious part of calibration point where all the greens and the oruntil they’d left. ange LEDs come on each time you blow The cigarette-lighter lead supplied with the kit has an integral fuse and LED plus a 2.5mm DC plug. You can cut this off and solder direct but be warned: red is negative, not positive! into it, then slowly die down again. If all you get is red LEDs, you’ve either got the calibration pot way too high – or you’ve sneaked a couple more beers without us looking. Once you get it to work, get your mate to repeat the process. Remember it takes a while for the alcohol to enter your bloodstream and then your breath so results do change significantly over time. And to finish… Finally, let us repeat the warning we started with. This device must NOT be relied on to give any real test of sobriety or otherwise, let alone the ability to drive. Only the Police Breath Analysis Unit or a hospital blood test can do that – by which time it is probably too late. SC Where do you get it? The Breath Tester project, including the PC board pattern, is copyright © 2000 Oatley Electronics Pty Ltd. They have available a complete kit of parts, including the disposals case and the cigarette-lighter lead, for $29.00 inc GST plus $7.00 pack and post. Contact Oatley Electronics at PO Box 89, Oatley NSW 2223, or phone (02) 9584 3653, fax (02) 9584 3651, website www.oatleyelectronics.com.au October 2000  33 SERVICEMAN'S LOG Two Teacs before bedtime Teac appears to be the flavour of the month at the moment, with two sets in quick succession. But the name – and difficulty – were the only similarities. And a whinge: why do interconnecting leads always seem to be too short to facilitate internal access? Mr Astor’s TV set looked almost brand new. It was a Teac CTM5928TXT 63cm stereo set made in 1998 but it looked as though it had come straight out of the box. The fault was no picture. The sound was OK and by turning up the screen control on the horizontal output transformer, there was a fully scanned raster with retrace lines. But there were no On Screen Displays (OSD) and the Teletext wasn’t working on Channel 7. The first drama was getting a circuit diagram because, with about 20 ICs to deal with, I didn’t stand a chance without it. Eventually, a photocopy of the circuit arrived and I sat down with the CRO and coffee for a spell of signal tracing. My next problem was, as usual, access to the chassis. For some unknown reason, manufacturers are convinced they can save heaps of money by reducing the lengths of the cable so that it is almost impos­sible to reach the printed circuit side of the chassis without unplugging it. My theory is that they save on the wire to buy more screws to fix the back on – why on earth do some sets need a dozen screws to keep it on while others use just two plastic clips? Nowadays things are so bad that it sometimes takes two seconds to fix the fault and three hours to fit the back on. (Well, OK, slight exaggeration..) Anyway, I connected the CRO and followed the video from the detector, pin 17 of IC102 TDA8305A (TP102), through the sound trap and Q109 to IC303, TA8628N. From here, I followed the video from pin 9 IC303 to pin 17 IC305, TDA4565. And from pin 12, via R351, to pin 11 of IC304, TDA3504. I was on familiar ground now; this IC often fails in other sets and the fact that I had tracked the signal this far was very encouraging. And as I had predicted, that was as far as the signal went. It should have come out on pins 1, 19 & 20, as red, green and blue signals to the picture tube socket, but there was no signal on any one of these pins. Red smearing I fitted a 20 pin-IC socket and replaced the IC. Bingo! The picture, colour, on-screen display and Teletext were all re­stored. But the picture had smearing on the reds. I fitted anoth­er IC Items Covered This Month • Teac CTM-5928TXT TV Set. • Teac CT-M488 TV set • Sharp VC-H93X VCR • Grundig GCF404/CUC2401    TV set 34  Silicon Chip in case it was crook but it made no difference. Fed up with trying to work out the theory, I decided to replace IC307, the TDA4650 chroma decoder chip. I fitted a 28-pin socket and slotted a new IC into it – which changed the red smearing into a blue cast! What on earth was going on? Convinced I had another dud IC, I fitted one more. The picture was still bluish. On refitting the original, the picture reverted to its original red smearing. I decided to change IC308 TDA4661 which gives very similar problems in Samsung sets. This is an interesting chip as it is an electronic chrominance delay line designed to be used with multi-system TV sets. Regrettably, it made no difference. Next, I went for the soft option of asking Teac Technical Support for help. Unfortunately, despite many attempts, including faxing, I didn’t even get a reply. There was nothing for it – I would have to do it the hard way. This time I worked back from the CRT socket and could clear­ly see the overshoot on the red amplifier on pin 19 of IC304 (TDA3504) and on the R-Y line on pin 14 (TP301). This overshoot was also present on pin 8 on IC305 but there the overshoot va­nished; the R-Y signal input to pin 1 of IC305 was OK. I also noticed the same overshoot on pin 9 of IC305, which made me suspect C443 and R343 which are connected in series from this pin to chassis. I did find that increasing C443 from 270pF to 1500pF would actually “fix” the problem but I really felt that this “Australian Modification” was just masking the fault. Final­ly, I ordered and replaced IC305 (TDA4565), which fixed the fault properly. I was still intrigued about IC307 but trying out another TDA4650 did not alter the blue cast, even though the IC was from the same manufacturer as the original. Apart from T305 on pins 15 and 20, there are no adjustments available for this stage. I regret that I have no explanation and insufficient re­sources to find out. Eventually, I will probably find an answer and you will be the first to hear. Of course, Mr Astor was com­pletely blase about all this – he was just happy that his set had been fixed. The second Teac TV The next job was equally baffling but in retrospect, I should have known better. This was another Teac TV set, a CT-M488, owned by a Mrs Masters. It was dead to all intents and purposes; no sound, no picture and no controls. On the positive side, the CRT filaments were glowing, there was voltage on the horizontal output transistor’s collector and there was even EHT. The standby LED worked too. Turning up the screen control on the horizontal output transformer, T402, pro­duced a white line across the screen. Ah, yes – we have all seen these symptoms before! The elec­ tros in the power supply dry out, the HT rises and the secondary voltages on the horizontal output transformer destroy the verti­cal output IC, plus the 12V zener. A quick look at the two capacitors in the power supply confirmed this and so without further ado I replaced them: C508 and C509 and the vertical IC U401 TDA3653B. But I couldn’t find a zener diode. Now at this stage, I didn’t have a circuit diagram. There were voltages on all the supply rails but I could only take a stab at the values, though they were what I might possibly ex­pect. They certainly weren’t unreasonable, considering that there was still something wrong. The loss of vertical deflection was still the major symptom so I decided to check around IC U401. I had about 20V on either side of D407 into pin 6 but no vertical drive going in (pin 1) or out (pin 5) of IC U401. Running my fingers across the pins could cause a momentary vertical scan jump, which suggested that the vertical output stage was probably OK, so I moved along to the jungle IC, U201, TDA8362. I checked there were volts applied and the crystal was oscillating but that was as far as I could go. I ordered a new jungle IC (U201) and a circuit diagram and moved onto some other jobs while waiting. When they arrived, I fitted the new IC and was bitterly disappointed that it didn’t fix the fault or alter anything. More money down the drain... But now I had a circuit and could check voltages against it. This confirmed that the 5V, 8V, 12V and 14V rails were all correct, if maybe a touch low. I was getting desperate and losing October 2000  35 Serviceman’s Log – continued I examined and cleaned the control head carefully but could find no fault with it. Then I checked the back tension and that was OK too. I also noticed that moving the ribbon cable to the head sometimes seemed to have an effect but it was not consist­ent. After a lot of continuity tests I found nothing wrong with the connections. Finally, I fitted a new ACE head. I hate changing these things, as to do the job properly, one needs a full alignment kit which costs three arms and a leg. Still, I managed by eye and was relieved to find that this finally fixed the fault. I can only attribute the problem to loss of sensitivity in the control head. Anyhow, Mr Worthinton was happy with the result. Standards conversion job the plot somewhat. Because I couldn’t get any of the controls to work, I next turned my attention to the microprocessor U101 PCA84C641P/524 and EEPROM U102 24C01CB1. Replacing them both made no difference. I then decided to try another trick. By monitoring pin 41 of U101, I could measure whether it was going high or low with the set being switched from standby to on, or vice versa, and I followed this through Q103, Q505, Q506 and Q507. The voltage varied up to the base of Q505 but it wasn’t changing from the collector onwards. Also, and quite significantly, I noticed that the voltage at TP502 was low at only 85V instead of 110V. I checked Q507 and Q505 out of circuit and these were OK but Q506, a 2N5401, was unserviceable. This was replaced with a BD238 high-voltage PNP transistor which has more rugged specifications. Fitting it restored all the functions – picture, sound and vertical de­flection – in one hit. I was surprised that a drop in the HT rail could make such a huge difference but of course I had broken one 36  Silicon Chip of my own maxims – when in doubt, measure the HT and, I should add, check it against the service manual! Hungry Sharp VCR Mr Worthinton brought in his Sharp VC-H93X VCR, complaining that it was chewing up his tapes. It didn’t take long to work out that the back tension brake pad had come loose and the brake pad glue was almost permanently gluing onto the supply spool. I ordered a new one, thinking that would be the end of it. When it was fitted, it fixed the tape chewing problem but left a more serious fault. The tracking (auto or manual) was now all over place and the set was switching from standard play to long play and back again. This is usually an ACE (Audio Control Erase) head problem and can be attributed to a tape path fault. Though it was diffi­cult, due to the constantly changing speed, in the end I was satisfied that I had defeated the gremlins and that the tape path adjustment was spot on. I tried a new pinch roller but that made no difference. My next story is one I wrote some years ago for the TETIA newsletter. I have resurrected it as I feel that it’s a classic example of how far one has to go in order reach a satisfactory outcome. No, it wasn’t particularly profitable but it was a valuable technical exercise and a very satisfying one. The set was a Grundig P40-245 GB/VHF-UHF Super Elite GCF404/ CUC2401 owned by a Scotsman, originally purchased in the UK and which obviously needed to be converted to Australian standards. Exactly what happened at this stage is rather vague. Apparently an attempt was made by someone to make the conversion but without success. It was brought to me by the owner who complained of no picture or sound. This was after he had taken it elsewhere and been informed that no parts were available. In the late 70s and early 80s, the Grundig agencies had a woeful reputation, changing hands every two years or so and most agencies going bankrupt. I was informed by one agency, which hadn’t yet gone to the wall, that no spare parts or service information was available for this set in Australia. By using contacts in the UK, I managed to acquire the tele­phone number of Grundig UK. At midnight (our time) I phoned this number, only to have the receptionist suggest the customer return his set to the retailer who sold it to him – 19,000km away! Eventually I obtained the name and fax number of Willow­vale Electronics, UK, who were very helpful – except that they insisted on replying to my faxes by snail mail. Finally, an IC, IC2200, TDA 5510-2 was ordered, arrived and this fixed the “no picture” problem. Problem No.2 turned out to be an incorrect modification of CCIR1 to CCIR B. It is far easier to modify a 5.5MHz colour carrier circuit to 6MHz than vice versa, because 6MHz is further away from the 4.43MHz colour sub-carrier and it is also easy to forget the sound trap in the luminance circuit, (F2221) as well as F2225 and F2231. Fortunately, this set wasn’t fitted with a Nicam decoder, because Australia uses a Zweiton stereo decoder and I was able to sort this out. But this led to problem No. 3. With all this unwanted hassle, I had quoted a substantial figure but one which the owner had accepted. Now that all the problems had been solved, the customer was informed that the set was ready. But because of the enormous delay in obtaining service manuals, parts, etc and because he had encountered a personal down­sizing situation, he now had difficulty in raising the money he owed me. So, I agreed he could pay in instalments while I kept the set on continuous test in the shop. This was OK and after three months he finally paid the last instalment. I unplugged the set, which had been performing faultlessly and he took it home. Problem No. 4 reared its head only three or four days later when a now irate customer returned, complaining of no sound. I asked him what he did to it and he said all he did was adjust the fine tuning and the sound suddenly went. I admonished him gently, saying there was really no reason to adjust the fine tuning as I had already done that and he had been able to receive all five Sydney channels perfectly when he collected the set. Nevertheless, I said I would look at it. And indeed I did. I looked and looked and looked. I spent a very long time trying to decipher why there was no sound (remembering this model re­ceiver was an orphan and operating on the other side of the world). I could find nothing wrong with the set but, by connect­ing pin 7 to pin 8 via a 0.47µF capacitor on IC2240 TB 130-2, full volume could be restored, suggesting that it had to be a volume muting problem. With much difficulty, cost and time, I obtained a new IC2240, IC811 and IC2705 and fitted them – to no avail. The problem had to lie on the SDA, SCL or KOIN data rails. Being totally unfamiliar with all this, I checked a variety of signals and pulses and found all the DC voltages to be what I guessed they might be. (The service manual is very poor in this aspect too). In the meantime, I faxed, phoned and wrote to all sorts of contacts around the world, including Southern Cross Electronics (who lent me a microfiche copy of the circuit but no description). With the exception of Willowvale, the apathy of the response from Grundig UK was incredible and I was getting nowhere. Finally, in despair, I was staring at the control panel in hatred, with the instruction book and service manual on my lap, when I noticed that the set had an extra control not marked or shown on any document. This was a pushbutton marked “ ” which is normally the symbol for a stereo balance control. But this was a monaural TV receiver. The penny dropped! Our customer had pressed this button instead of the fine tuning button and then he had pressed “+”. The microprocessor had obeyed precisely, turning down the left channel (presumably the main monaural one) and turning up the non-existent right channel, giving no sound. By pressing the balance control button again and then the “-” button, full sound was restored! I charged the customer for only another hour’s labour but felt like sending Grundig International a bill for the rest of the SC time and money wasted. October 2000  37 I Spy With My Little Eye “Necessity is the mother of invention”, so the proverb goes. OK, so this little project isn’t quite an invention. But it was born of necessity. A few weeks ago, I had to install some burglar alarm wiring deep within a brick cavity wall. The architraves and door jambs were not yet fitted, so I had quite good access to the cavity. But the view inside the cavity was well and truly hidden by a bunch of power cables. I tried all the usual tricks of “fishing” for the alarm cable – yellow tongue, thin dowel, a telescopic wand, straightened-out coathanger – but nothing worked. Not only were the power cables completely blocking my view, I was at least a little wary of a power outlet one of them connected to (especially when poking around with the coathanger!). “If only I could see inside the wall…” It was about this time that I remembered seeing not one but many advertisements for small, relatively cheap TV cameras. Could I use one of these to be my eyes inside the cavity? If so, how? I wanted to know more about these cameras. They are available from many SILICON CHIP advertisers, with a range of prices as wide as the range of models and types. You can get colour or black By Ross Tester & white, various shapes and sizes, with various lenses and various resolutions, or quality. Most of the cameras, though, would be too big for this application. The majority are built into relatively small metal cases, usually around 32 x 32 x 20mm. Given that the average wall cavity is only about 25-35mm wide, these would either be a very tight fit – or no fit. Then there are the “micro bullet” cameras – longer but certainly thinner – mostly around 22mm diameter and about 60mm or so long. Now these were starting to look interesting! Of course, we’d need to come up with some type of mounting arrangement so as to get the camera right into the thick of the action, where it was needed. We were just about to order one of these bullet cameras when we spotted what appeared to be an even better choice. Along with the rest of their range of cased video cameras, Oatley Electronics were advertising a 380 TV line “Super Micro” CCD camera module – no case, just the module. The camera we selected is a “Super Micro B/W” from Oatley Electronics and it is micro – just 17mm wide, 16.5mm deep and 60mm long! At right is a front-on view of the same camera. We take advantage of the two bosses (on each side of the camera) to not only hold the unit in place in the slots cut in the conduit but also to mount the two infrared LEDs. 38  Silicon Chip Pic to come While not waterproof or apparently as robust as the micro bullets, they were smaller – 17mm wide and about 22mm across. And there was another advantage – their power supply was a lot less demanding – they’d work from about 9.5V to 14.5V where most of the other cameras needed a regulated 12V supply. The price was attractive, too: less than $100. While not available in colour, we reasoned that colour would be a luxury we could do without. Besides, we planned some form of infrared illumination so colour would be meaningless. So that was the camera we decided to go with. Now we could turn our attention to the “probe”. Initially, we planned to put the camera inside a length of PVC electrical conduit. The conduit would give rigidity but also (importantly, we believed) give very good insulation just in case the end came in contact with live wiring inside the wall cavity. An example: the back of power outlets and light switches are not covered and they usually have at least some live “bits” (screws, etc) which might be contacted. Admittedly, contacting them was fairly remote but we believed even a remote possibility should be eliminated. Out first prototype was made using a length of UPVC conduit. And while it worked most of the time, we found a problem in operation. If we struck an obstacle within the cavity (eg, those damn power cables!) we could “jiggle” the conduit around but we couldn’t twist it out of the way. What we needed was the ability to create a small bend in the end of the conduit “on demand” – most of the time it should be straight but if Searching inside a pitchblack cavity for an elusive cable is never easy. Our spy camera puts the odds way back in your favour. The very bright spot on the monitor is a timber joist right in front of the camera, illuminated by the two infrared LEDs fitted to it. Looking inside the cavity it was still pitch black – but the camera responds very well to infrared light. obstacles were struck, a bend would allow it to be twisted out of the way. How do you create a tight bend in PVC conduit? You cannot, of course – unless you use flexible conduit. But this normally would not be practical because it is too flexible. It also tends to coil because that’s the way it is supplied. To solve this problem, we used a combination of both standard and flexible PVC conduit, one telescoping inside another two. By trial and error, we ended up with a 0.5m length of 25mm flexible conduit, a 3m length of rigid 16mm PVC conduit and a 1m length of rigid 20mm PVC conduit. The third length of conduit was used to allow the slack in the cable to be taken up – but more on this shortly. Most of the time the rigid conduit slides almost all the way up the inside of the flexible conduit, effectively There’s not much required in the way of circuitry – most of what you need is already in the camera module. The camera can be run from a 12V battery for “away from power” operation (assuming you had a battery monitor) and the regulator circuit eliminated but we would still retain reverse-polarity protection diode D1 – just in case. October 2000  39 straightening it out. But if a bend is needed, some of the rigid conduit is withdrawn from the flexible, which can then curl. Originally we used a pin through both conduits to stop the flexible length sliding right off (it would be nasty to lose it – and the camera – inside the cavity!). We drilled holes for this pin every 100mm (up to the 500mm length of the flexible conduit) so that the amount of bend could be set as required. With the two conduits separated most of the way, the conduit bent more than 90°. With the two telescoped all the way in, the bend was minimal – no more than a degree or two. Having made the prototype this way, we now have an even easier method of controlling the bend and also preventing the flexible conduit sliding off. This involves the third length of conduit, the “handle” we mentioned before. By fastening the flexible conduit and the “handle” together with a suitable length of cord (eg, venetian blind cord) the two conduits would slide along the inner conduit as one, not only setting the amount of bend but ensuring the flexible conduit remained captive. is required, or even better, a small 1W type (if you can find one). We’ll show how we arranged the LEDs shortly. Illumination Power We mentioned before our plans to provide illumination. Because we are interested in the immediate area of the camera, only a small amount of illumination is required. We used two infrared LEDs in series which were powered from the same 12V supply as the camera, via a suitable resistor. These are run pretty hard to get the most light output. The current is limited by the 180Ω resistor to about 50mA, the maximum forward current of the infrared LEDs. With this, the level of illumination was more than adequate. In fact, it was great for the purpose! The only minor dilemma is the dissipation of the resistor – at 50mA, it’s about 0.35W so a 1/4-watt resistor (which are pretty standard these days) simply isn’t enough. A 1/2W resistor One of the features that attracted us to this particular camera (apart from size) was that it is quite forgiving when it comes to the power supply. It could handle from 9V to 14.5V DC. Most of these small cameras, especially the colour ones, demand a regulated 12V supply (in fact, you’ll void the warranty on some if you don’t use a regulated supply). So theoretically, we could run the camera from, say, a 9V plugpack. Why not a 12V plugpack? Off load, most 12V plugpacks deliver more than 12V – often alarmingly more. You may recall an article we presented in SILICON CHIP in December 1998 on how to regulate a 12V plugpack for this very reason. In that article, we pointed out that a typical 12V 1A plugpack delivers from 15-18V on light loads. It’s only when you start to draw near the rated current that the voltage becomes close to the rated output. So that would rule out a 12V plugpack because the maximum camera supply is 14.5V. Or would it? Why not do what we did in that previous article and add a 12V regulator. For the sake of a couple of dollars, we could ensure a 12V supply regardless of what ills the plugpack tried to hit the camera with. Into the bargain, we would remove (or at least minimise) the hum and noise which is typical of most plug-packs – resulting in a much clea-ner picture. This photo shows how we connected the two infrared diodes to the camera PC board (via a 180Ω resistor), at the point where + and – power comes in via a 3-pin plug on the other side. They were held in place with a dab of super glue. 40  Silicon Chip The drawing above and the photographs alongside show how the cavity camera was assembled. Of course there are other ways to do the same job – you may come up with even better ideas! One real “tricky” bit in this assembly was lining up the Veroboard to get the bolt through the hole. Perserverance pays off... So that is exactly what we did: made up a small regulator using a 7812 3-terminal regulator and an electrolytic capacitor. The value of the capacitor isn’t important – just as large as you can get into the conduit. 16mm conduit has an internal diameter of about 12mm and then we had to get the cable past. We found a 470µF, 25V capacitor which just fitted nicely. You might have to have a good search of your junkbox or do the rounds of the lolly shops to find a suitable electro. Of course, the whole power supply/ regulator could be eliminated if you wanted to run the camera from a 12V battery (and you also had a 12V monitor). Cable At one stage, we were planning to use thin 75Ω coax cable to run the camera to the monitor. Then we were going to run the 12V supply up the same coax, suitably isolated at both ends, of course. (This technique is used in just about every masthead amplifier installation, so we weren’t re-inventing any wheels). But then we discovered some very thin, very flexible shielded twin cable. Intended for audio applications, it has two individual insulated conductors surrounded by shield braid. It had two big advantages: each of the inner con- ductors were multi-strand, meaning it could be flexed a lot without damage. And it was significantly thinner than even the thinnest coax cable commonly available. (Yes, you can get ultra-thin 75Ω coax, around 1mm in diameter. Trouble is, you can only get it at specialist suppliers and then only in 400m rolls. And it ain’t cheap!) So instead of having to provide extra comAnd finally it’s finished with the addition ponents (RF chokes and of our proprietary “cotanger” hook. capacitors) to isolate the wasn’t even intended for video use. supply on the coax, we That means there would almost cercould run video in one of the conductainly be an impedance mismatch tors and power in the other. Simple, with both signal loss and unwanted convenient! The cable, by the way, reflections. But what the heck, we came from Jaycar Electronics and sells were only looking at a couple of mefor only 77c per metre (Cat. WB-1504). tres or so . . . and just about every video Of course, the shielded cable we cassette recorder user knows that you were considering wasn’t 75Ω; it October 2000  41 Parts List 1 AR-717R “Super Micro B/W” Camera Module (Oatley Electronics) 1 3m length 16mm UPVC electrical conduit 1 1m length 20mm UPVC electrical conduit 1 500mm length 25mm UPVC flexible electrical conduit 1 20mm PVC conduit end cap 1 20mm length 20mm UPVC electrical conduit 1 piece of Veroboard or similar, approx 12mm x 20mm 1 30mm heatshrink tube, approx 50-100mm long 1 RCA socket, chassis-mounting type (ie nut fastened) 1 2.1mm DC socket, chassis mounting (Jaycar Cat PS-0518 or similar) 1 small cable tie 3m twin shielded thin mulitstrand cable (Jaycar Cat WB-1504 or similar) 3m thin cord (eg, Venetian Blind cord) 1 wire hook, fashioned from heavy wire 1 30mm x 3/16in (approx) bolt, nut and washer(s) Semiconductors 1 7812 12V positive regulator 1 1A silicon diode (1N4001 or similar) 2 infrared 5mm LEDs Capacitors 1 470µF (or 1000µF) 25VW electrolytic capacitor 1 0.1µF capacitor, small (type unimportant) Resistors 1 180Ω resistor, 0.5W or small 1W (brown-grey-brown-x) can use ordinary figure-8 shielded for short distances. So why not? We gave it a go and voila! It worked perfectly. If there was signal loss or degradation, we couldn’t see it and, considering what we were going to use the system for, it didn’t really matter if there was. The monitor Here’s where many people might think they are going to come unstuck. But fear not! The output of the camera is standard composite video, 1V peak-peak. You’re going to need a monitor (mono or colour) which accepts this composite video. It cannot be fed into the antenna input because it’s not RF, á lá an off-air signal. Before you think “stymied” the vast majority of modern TV sets have video inputs. It’s often called an “AV” input. Yes, it is a bit inconvenient to lug around a 34cm TV set but it’s a price you might have to pay if you don’t want to invest in something smaller. As a matter of interest, we used a 14-inch Commodore computer video monitor which we rescued from a recent council cleanup. These monitors, originally used on Amiga computers, have a composite video input. Total cost? $0.00! What other options are there? If you want the smallest and lightest monitor possible, have a look at the range of tiny tellies at your local electronics or specialist video store. For example, Dick Smith Electronics has a couple of 10cm and 25cm colour TVs with A/V inputs which would be ideal. And when you’re not using it with the camera, you can watch TV! Another alternative would be a B&W security monitor. Jaycar Electronics have available two b&w monitors under $200 which would also be perfect. One is a 6" model and sells for only $123.54 while the larger 10" model is $190.58. Obviously, we haven’t tried these out but cannot think of any reason why they – or any other monitor which takes a standard composite video input – wouldn’t work perfectly. If you really needed to use a TV set without video input, you could always add a VHF or UHF modulator and then you could go in via the aerial socket on any TV set. Oatley Electronics have available a high quality linear modulator which suits this camera perfectly and gives an excellent picture on even el-cheapo TV sets (not always easy!). As a special favour to SILICON CHIP readers, Oatley Electronics will give you one of these modulators (yes give you one, totally free) when you purchase the video camera, just as long as you ask for it at the time of purchase. Some suitable monitors from Jaycar and Dick Smith Electronics These monitors and TVs have not been tried but should work perfectly with this camera. 6-inch b&w switching monitor from Jaycar, Cat QM3402, sells for $123.54 42  Silicon Chip 10-inch b&w security monitor from Jaycar, Cat QM3402, sells for $190.58 25cm 12/240V colour TV with A/V input from DSE, Cat G7230, sells for $460 10cm AC/DC colour LCD TV with A/V input from DSE, Cat G7240, sells for $368 Now that’s not a bad deal at all! So the options for monitors are much wider than you might imagine. It all depends on what you want, what you may currently have (or scrounge) or whether you need to buy something new. Construction The first step is to fit the two infrared LEDs to the camera. We soldered the LEDs together in series then secured them to the camera body with a couple of drops of super glue. The 180Ω resistor was soldered direct to the back of the camera PC board, immediately under the 3-pin connector. The other end was soldered to the anode of one of the series LEDs. The negative connection was made with a short length of flexible hookup wire, again soldered to the back of the PC board at the negative power connector and to the cathode of the other LED. The pads to which you solder the resistor and wire are pretty small, so you’re going to need a fine-pointed iron and a steady hand. It helps if you work under a magnifying lamp. To connect the camera to the outside world, a tiny three-lead plug connects to a socket on the PC board (the same socket we just soldered to on the other side of the board). The blue lead is a common ground for both power and video. The red lead is the positive power lead and the yellow the video output. We were a bit concerned about the fragility of this plug and socket system so made up a small connection board from a scrap of Veroboard. The whole point was to minimise any stresses on the leads to the camera, or the socket. The shielded cable was anchored to the Veroboard with a tiny cable clamp – the smallest we could find. As we said before, we housed the camera inside a short (500mm) length of 25mm flexible electrical conduit, into which telescoped a 2m length of 16mm PVC electrical conduit. The camera mounted just a little back from the end of the conduit, mainly to avoid damage to the lens. The way we mounted it was a little different: all we did was cut 30mm long slots in both sides of the end of the flexible conduit with a small angle grinder and slid the camera assembly inside, LEDs and all. The LEDs ended up sitting in the slots immediately in front of the camera bosses (see photo). The position of the LEDs was chosen carefully to be just behind the lens, thereby avoiding any light scatter. When we were satisfied with the position, the whole lot was sealed in place with some heatshrink tubing which locked it up tight. Of course, the heat applied was just enough to shrink the tubing: we didn’t want to risk damaging the camera. By the way, we obtained the length of flexible conduit from a local sparkie – in fact, it was on the rubbish pile on a building site. If this source isn’t available, you can buy flexible conduit by the metre at most electrical wholesalers. Likewise, the 16mm and 20mm conduit can be obtained from the same source (or, in fact, virtually any hardware store). When the inner conduit is tele­scop­ ed in as far as it can go, the flexible conduit is almost straightened out, so the camera points straight ahead. But if it is slid out by, say, 200-300mm, the natural curl of the flexible conduit takes over and the camera points in that direction. Rotating the conduit points the assembly, camera included, in a different direction. Naturally, when you rotate the conduit and the camera rotates, the picture also rotates. This can be a little disconcerting at first – by far the easiest way to “get your bearings” is to rotate the monitor by the same amount. Here’s where having a small monitor is a real blessing! We were concerned that the inner conduit might be jammed up against the camera board, causing damage, if it was telescoped too far into the flexible conduit. So we made a “stop” out of a short length of 20mm conduit (again, a scrap from a sparkie) which we secured inside the flexible conduit with a nut and bolt through the whole thing. This bolt also provided a mounting point for our wire hook which we fixed to the end of the conduit to help capture the wayward cables inside the wall (which, after all, is the whole purpose of the exercise). The diagrams explain how we put all this together; naturally you may choose to do it differently. Our hook was made with a piece of extremely difficult-to-obtain proprietary wire called “cotanger” (we may not have spelt that quite right), bent to an appropriate shape. (We used to see October 2000  43 old Valiants driving around with this wire used as a radio antenna but even this has gone out of fashion now...) By the way, the 20mm “stop” doesn’t really want to fit inside the flexible conduit. We overcame this by heating the flexible conduit with a heat gun (very carefully) so that we softened the PVC just enough to force the short length in. We did notice some degradation of the plastic at this point; perhaps you might like to make a smaller stop (say from a piece of dowel) and drill a hole through it for the wires to pass through. At the “user” end, we slid another 1m length of 20mm PVC conduit over the top of the 16mm conduit. The reason for this is threefold: (a) it gives a more rigid “handle” with which to control the camera; (b) it allows us to place power and video connectors inside; and (c) perhaps most importantly, this controls where the flexible conduit at the other end sits on the inner conduit. Sliding the handle all the way on allows the flexible conduit to slide nearly all the way off, thus bending. Sliding the handle back, almost all the way off, pulls the flexible conduit back on to the inner conduit, thus straightening it up. As we mentioned before, something we didn’t do (and now regret) was connecting both sliding conduits together with a length of thin cord. This would stop either coming right off the inner conduit; it would also prevent the connecting cable being stressed or broken. We would recommend fitting such a cable, as shown in the diagram. You might find the 16mm conduit a very tight fit inside the 20mm conduit – it depends a lot on brand. We had this problem but easily overcame it by giving the end of 16mm conduit a good rubdown with some gritty glass paper (about a grade 60 or so works well). Power and video connection A 2.5m length of the twin shielded cable connects the “camera end” to the “user end” of the conduit. At the “user end”, we terminated the cables in two ways. The positive (red) wire went to the output of the regulator. Its input was wired to a 2.1mm DC socket which fitted – just – inside the 20mm conduit “handle” we mentioned previously. The other wire (white) was 44  Silicon Chip soldered to a standard RCA socket for the video connections. This socket didn’t fit inside the conduit so we placed an end cap over the 20mm conduit and fitted the socket in that. Naturally, the common earth (braid) was wired to both the DC socket and the video socket. The braid was in fact looped through the hole in the regulator tab, then soldered to the tab itself (which is also a “common” or ground connection). Our old Commodore monitor cost us nothing but is This means that the still great for use with this camera. The photo doesn’t majority of the stress do the image on the screen justice but it was of a on the cable is on the virtually pitch black cavity illuminated adequately by braid, which is the the two infrared LEDs. strongest part of it. We marked its position on the end Even so, with rough handling the thin of the coax and drilled holes before cable can break – so take it easy. The regulator (and its capacitors) assembly, then slid the 20mm conwere wired point-to-point with the duit length onto the 16mm conduit, minimum practical lead lengths (to made all our solder connections, then avoid shorts) and pushed inside the pulled the 20mm length back out a conduit before the DC socket was bit, pushed all the bits inside, lined up the DC socket with its mounting screwed in. holes and fixed it in place with the The larger electrolytic was chosen screws. not so much by value but by size – as The end cap was then slid hard onto large as we could easily slide into the conduit, while still leaving some the 20mm conduit and the assembly clearance for both the wires and cord. was finished. We didn’t use any PVC jointing compound in case we needed A minimum 25V rating is required; we found a 470µF about the right size to disassemble it (which, by the way, we did to fix a broken cable!). (also ‘cos we had one!). A 1000µF, 25VW would also be a good choice if In use physically small enough. The photo of our video monitor Follow our diagram when wiring the supply and you shouldn’t have any shows just how effective our spy camproblems – but one thing to make sure era is. Inserted into a virtually black cavity, it had no problem finding the of is the connections to your plugpack. Usually, the centre pin is positive but cable of interest – a cable which we had been unsuccessfully trying to there are many exceptions! retrieve for days. If there is any danger of plugging in As we said before, using the camera the wrong plugpack, a series protection diode wouldn’t go astray. In fact, with the image on an angle or upside having said that, there is always dan- down can be a bit tricky – until you get ger of plugging in the wrong plugpack used to it, turn the monitor to match the vertical! especially in many month’s time – so we’ve now fitted (and shown) a 1A When not in use diode in series with the supply. Always store the assembled unit The 2.1mm DC socket may cause you some problems. Most available either on a shelf or supported in at least 6 places. The 16mm conduit these days are too big to fit inside especially is very flexible and will the conduit – we used a PS-0518 DC sag significantly, taking on that shape socket from Jaycar which, with a bit semi-permanently after a while. SC of convincing, fits in! 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. 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 Features: me ss in boot volu • Very little lo en installation • Largely hidd an an addition to • Suitable as al equipment system existing origin ots sedans with bo • Suitable for kers of suitable spea • Wide range Installing a Free-Air Subwoofer in Your Car This design removes many of the space and weight compromises of car subwoofers. It is ideal for those wishing to upgrade the standard sound system in a late-model sedan. By Julian Edgar O ne of the major problems with car subwoofers is that they take up a lot of space. A small, well-designed subwoofer enclosure fills about forty or fifty litres but the situation is in fact even worse than that. When you locate a large, square box in the boot, you find that lots of the nooks and crannies that were previously available to be filled by soft bags are now impossible to access. The other major drama with a conventional car subwoofer is that it’s heavy. By the time you incorporate thick MDF panels and the driver itself, you can easily have added 40-50kg – weight whose fare you pay for at the petrol pump every time you fill up. So how have we overcome these problems? OOctober CTOBER2000  53 2000  53  Like many modern cars, the Audi has a central rear armrest that folds down into position. However, no opening through to the boot is then created – a steel panel remains in place behind the leather trim. A hole for the subwoofer grille could have been cut in the plate using a jigsaw equipped with a metal-cutting blade, however…. Simple – we’ve used the boot as the speaker enclosure! This type of free air (infinite baffle) design makes use of the hundreds of litres of boot volume that’s available the majority of time that the boot is not full to the brim. And when you want to place some luggage in the boot, there’s no problem at all – the speaker enclosure just gets a little smaller! However, it should be noted that using a free-air subwoofer does not give the same sound quality as a subwoofer mounted in a smaller, carefully-designed (eg isobaric) enclosure. Also, the power handling of the Because a large speaker cone area will allow the movement of a lot of air for minimal cone dis-placement a ten-inch speaker was selected. However, the ski-port opening width would not permit a ten-inch diameter grille, with a 6.5-inch grille being most appropriate. As a result, a spacer ring was cut from MDF, allowing the speaker to be mounted to fire through the smaller hole without its rubber-roll suspension coming into contact with the baffle. You could of course use a subwoofer driver whose diameter matches the available grille diameter. 54  Silicon Chip 54  Silicon Chip  … when the interior boot trim was pulled away, a factory pre-cut opening was revealed. In some markets this car is equipped with a “ski port”, but in this particular model the plate was not fully cut out. Some judicious use of an angle grinder soon removed the short pieces of metal that held the blanking panel in place, allowing the easy creation of a rectangular opening. driver will be reduced over that which would have been possible in a smaller enclosure. But taking the approach outlined here is ideal for people owning a late model sedan that’s equipped with a decent sound system. It just lacks the required bass punch. Selecting the Driver There are two major criteria to examine when selecting the most appropriate driver. First, how much space is available to mount the speaker? In the example discussed here, the speaker was positioned so that it fires through a grille located behind the rear seat armrest. Other methods of mounting include positioning the speaker so that it works through a hole cut in the rear deck, or so that it fires through one side of a 60:40 split rear seat. In many cases (especially in those cars that do not have a metal panel behind the rear seat) the speaker can be located so that it works through the back seat itself – a large speaker driven with adequate power will still be quite effective, even with no direct air connection with the cabin.  The Soundstream Rubicon 10 can be seen mounted on the baffle with the spacer ring. Only four bolts were used to mount the baffle board against the metal panel across the rear of the seat. High tensile nuts and bolts (available from auto accessory suppliers) were used so that they could be adequately torqued without failing in the way all too familiar to those who use common hardware store nuts and bolts!    Note that if the grille area of the new speaker is limited in diameter – but the rear mounting space is plentiful – the selected speaker can be larger than the grille. The Audi S4 installation shown here used a ten-inch speaker and a 6.5-inch grille. The second criterion is that the speaker must have appropriate specifications that allow it to work effectively in a free-air environment. In simple terms, the speaker’s suspension must be stiff enough that the speaker cone will not bottom-out when working hard, even without the Once the opening through which the speaker is going to fire has been created, an MDF mounting board should be cut to size. Don’t be tempted to use chipboard for this piece – it will easily crumble at the edges and also have poor strength and vibration dampening abilities. The piece of 18mm MDF was sized so that the selected driver and amplifier could be mounted on it, with room left for another amplifier, for later upgrading of the system. restoring force normally generated by the springiness of the relatively small volume of air trapped behind the cone. Manufacturers and retailers selling automotive subwoofers have available recommendations for appropriate enclosures for each of their speakers. If these include infinite baffle or free-air types of enclosures, then the speaker can be used in the type of application being discussed here. (If no specific recommendations are made, look for those that drivers that have a high Qts value – eg, above 0.6). The power rating of the driver  The mounted driver, viewed from the ‘seat back’ side. The eight screws and nuts that were used to hold the driver in place were countersunk so that the baffle board could fit snugly up against the panel behind the seats, without the heads of the screws coming into contact with the panel. The five recesses (cut with a large drill bit) around the edge of the speaker opening are there to take the five prongs present on the grille that was used. (More on the grille later.) Note the offset of the speaker relative to the opening.   Once the fill panel had been removed, tough rubber edging was placed around the exposed metalwork. When performing any work on a car, the potential for injury from sharp edges (especially in a vehicle accident) should always be considered. The type of edging used here is quite strong, as it uses internal spring metal clips to really grab the edge over which it is placed. This edging was purchased from a rubber store. should also be appropriate for the amplifier that is going to be used to drive the sub, noting that the efficiency of a free-air design is lower than that achieved with the same speaker mounted in a ported enclosure. We used a Soundstream Rubicon 10 subwoofer, with a program power handling of 250 watts. This is the same driver that we used in the Bass Cube ported subwoofer, featured in the April 1999 issue of SILICON CHIP. A very versatile speaker, it can be used in infinite baffle, sealed, ported and bandpass enclosures. It costs The panel across the back of the Audi’s rear seats has multiple ribs and other shapes pressed into it to provide structural stiffness and prevent vibrations. So that the MDF baffle would adequately seal against the metalwork (and also to prevent rattles), self-adhesive high density foam rubber strip was attached just inside the periphery of the baffle. It attached the foam rubber to the clean board surprisingly well. Note the mitred join at the corner – a dob of contact adhesive was used to join these faces firmly together.  October 2000  55 OCTOBER 2000  55  The baffle was then bolted into position but not before some thought had been given to how the trim panel was to be mounted. A panel was used to hide both the amplifier and the subwoofer driver. This must be mounted securely if vibration isn’t to be a problem. To allow for a firm mounting and to provide clearance to the amplifier, the baffle was extended by four pieces of 65 x 19mm timber, glued and screwed to the MDF and visible each side of the subwoofer in this picture. about $200 from Strathfield Car Radio stores and dealers. Selecting the amplifier The vast majority of modern cars use a four (or six) speaker system. Two speakers are mounted in the front doors or dashboard, often with an additional pair of tweeters. In the rear deck or rear doors another two drivers are positioned. Generally, line-level outputs (ie  The Audi has its battery under the back seat, so the positive supply cable for the amplifier didn’t have to travel very far! A heavy-duty in-line blade-type fuseholder was placed close to the battery and the heavy cable soldered to one of the main original power supply cables coming from the positive terminal. Note that the fuse should be placed as close to the battery as possible. Where the amplifier power supply cable came in contact with the bodywork edges, it was protected by having a piece of snugly-fitting fuel hose slid over the cable. RCA-type connections) are not available from the stereo systems (or “front ends”) installed by the vehicle manufacturers. These factors mean that an amplifier that will accept speaker-level inputs is far easier to integrate into a current system than one requiring line-level signals. In addition to having speaker-level inputs, a suitable amplifier should also incorporate a low-pass filter (preferably with switchable centre frequencies) and a bass boost switch (preferably with switchable boost levels). As the amplifier will be driving only the one subwoofer, it is also helpful if it can be wired in bridge mode, substantially boosting the output power. There are many car audio power amplifiers that satisfy all of these criteria – you just need to have a clear idea of what you want before venturing into a shop! In the Audi we used an older Coustic  With the trim board cut to approximate shape and a small hole cut to allow the rear of the subwoofer driver to project through it, the board was placed into position and markings made with a texta to show where further trimming was needed. Note that in the Audi, the trim board also needed to fit in front of (ie behind, in this view) the factory-mounted CD changer. And yes, I did get sick of getting in and out of the boot! 56  Silicon Chip As can be seen in this view – showing the trim panel temporarily in place to check for fit – the magnet and part of the speaker basket protrude through the panel. Incidentally, it was a deliberate decision that the trim panel be mounted not sufficiently rearwards to cover the rear of the speaker – doing so would also unnecessarily remove boot volume either side of the speaker. The hole for the speaker is at this stage a little small – but it’s easier to enlarge it than reduce its diameter!   amplifier, rated at 50W per channel and incorporating all of the points mentioned above. Secondhand, this type of amplifier can be picked up for about $150. Step-by-step photos While the photo sequence shows how the amplifier and subwoofer were installed in an Audi S4, with variations on the theme, this will provide a good SC guide for most sedans. The system can be tested, with attention paid to locating buzzes or other vibrations. Once happy with it, the trim panel can be made. If the car has as standard a trim panel that fits against the front face of the boot, this can be checked for fit in its new (more rearwards) position. If still a good fit, it can be used as a template to mark out the board that will now support it. Our trim panel used 5mm thick Masonite for the trim panel, pre-punched with 7mm holes, which allow airflow through the trim panel and reduces mass. Finally, a grille is gled into place. This grille is actually from a Volvo, obtained from a crash repair business specialising in prestige cars. It looks far more ‘original equipment’ than a typical aftermarket grille. The grille is completely hidden when the armrest is raised to its vertical position and in fact in this position, very little reduction in the subwoofer output occurs.  Car audio amplifiers use a remote switch-on input, triggered by 12V. This is most easily accessed at the electric aerial wiring – use a multimeter to probe the wiring to the aerial motor until a wire is found that has 12Von it when the radio is on, and 0V when the radio is off. Check this thoroughly – not all electric aerial wiring is as self-explanatory as it might first appear! If an electric aerial is not available, the remote switch-on power can be accessed from an ignition ‘accessories’ source.     To provide strong but attractive speaker protection, a cheap stainless steel mixing bowl was glued to the back of the trim panel using “water clean-up” Liquid Nails with a thick layer of quilt wadding glued into its recess to avoid hollow ‘ringing’ noises. The bowl was mounted with its flange against the back of the trim board but if less speaker clearance was needed, it could have been inserted from the other side. When the glue hardened, the bowl and back of the trim board were painted black with a spray can. A matching sized hole was cut out of the standard trim which was then glued to the new masonite trim backing. While contact adhesive can be used, small dobs of Liquid Nails is much cheaper and just as effective – and without the smell, too! The trim panel was held in place with black-head self-tapping screws, screwing into the four wooden pieces previously attached to the baffle. Standard black fasteners were inserted to fill the holes that would otherwise have existed in the trim (seen either side of the speaker). O October CTOBER2000  57 2000  57 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. D1 1N4004 1k B C E +12V VIA IGNITION SWITCH BALLAST RESISTOR Q1 BC337 330 IGNITION COIL 4.7k ZD1 8.2V Q2 BC557 C 22k BLACK .01F 470k 22k 5 C  E 6.8k 0.1F 0.1F _ ZD2 Q3 MJ10012 6 VCC 7 IO IC1 MC3334P 3 8 IL C RED A K 100 5W E B 120 0.5W 0.1F HT TO DISTRIBUTOR + S2 PGND SGND 1 2 4 x 1N4761 75V 1W C B ZD3 E ZD4 ZD5 WHITE CHASSIS CASE Opto-electronic version of high energy ignition SILICON CHIP regularly receives requests for modifications to published circuits and the High Energy Ignition System for cars – de­scribed in the June 1998 issue – is a popular example. Readers often want to use it with an opto-electronic distributor and most of these requests are met by a simple modification that was pub­lished in 58  Silicon Chip the August 1998 issue (page 91). However, this present version is aimed at a different opto-electronic pickup which has a common negative connection and has been implemented for the original version of the ignition circuit which was published in May 1988. Zener diode ZD1 and transistor Q1 make up a simple voltage regulator which delivers 7.5V at the emitter. This is used to supply the opto-electronic pickup which consists of an infrared LED and photo-transistor. This is used in conjunction with a light chopper disc on the shaft of the distributor. The current pulses produced by the photo-transistor are inverted by Q2 and fed via the 0.1µF capacitor and 22kΩ resistor to pin 5 of IC1. In other respects, the circuit remains the same as published in May 1988 but it can be adapted to the later version in June 1998. SILICON CHIP. the easy way into electronics This month we feature two Protoboard circuits based on the 555 timer. This chip must be one of the most popular devices ever developed but when it came out in around 1973, people won­dered what to do with it! The two circuits are quite similar to look at but they produce different functions and you can change from one circuit to the other in just a few moments. Most electronics enthusiasts know that the 555 can be used in timer and oscillator circuits and these are what we are pre­senting here. However, in each case we use two 555s and one is used to control the other. The first circuit (Fig.1) is a siren with one 555 being used to frequency modulate the second. The second circuit could be used as part of an alarm. It consists of a 555 oscillator which runs for a time determined by the second 555. Fig.3 shows the wiring layout for the siren circuit on a protoboard. As we did last month, the two ICs straddle the cen­tral channel of the Proto­board and the eight pins of each IC connect 60  Silicon Chip to individual conducting strips. The other components and jumper leads are then inserted to make up the circuit. Note that the three electrolytic capacitors must be con­nected the right way around (ie, positive voltage to their posi­ tive terminal) otherwise they will be damaged although initially, the circuit would probably work. You will need two potentiometers, both 100kΩ, but other values from 50kΩ-250kΩ will work just as well although produc­ing a different range of frequencies and times, as we shall see. The two pots are mounted on the vertical panel of our Protoboard’s metal chassis and then wired to the circuit. You will also need a momentary contact pushbutton switch and this is also mounted on the panel. The diode (D1) is wired in series with the DC socket for the 9V plugpack but it should also be included if you are using a 6V or 9V battery because without D1, a reversed DC supply will mean instant death for the two ICs. Note that supply from a 9V DC plugpack is likely to be closer to 12V because this circuit does not have a heavy current drain. Hook up all the components for the circuit of Fig.1, as shown in the diagram of Fig.3. Don’t hurry the job as you might make a tragic mistake. Even Fig.1: IC1 runs at a slow rate (about 0.5Hz to 2.8Hz) and it is used to frequency modulate IC2 which drives a loud­speaker. so, it will only take a few minutes to wire it up. On the other hand, if you are not confident with the task, just wire up the circuit involving IC2 first. This will produce an oscillator with a frequency which can range from around 200Hz to 700Hz, depending on how you set pot VR2. Scope waveforms The scope waveforms of Fig.4 and Fig.5 show the frequency extremes which can be expected at pin 3 of IC2. Fig.4 shows a waveform with negative pulses which are 700µs wide at a repeti­tion rate of 200Hz while Fig.5 shows the same 700µs wide negative pulses but at a repetition rate of 675Hz. The negative pulse width of 700µs (or 0.7 milliseconds) is set by the 0.1µF capacitor at pins 2 & 6, combined with the 1kΩ resistor to pin 7. The variable part of the waveform, the positive section, is determined by the 10kΩ resistor and 100kΩ pot connected to pin 7, the 1kΩ resistor to pins 2 & 6 and the aforementioned 0.1µF capacitor. So by varying the pot setting, we vary the overall frequency. By the way, both those waveforms were taken with the loud­ speaker disconnected (the noise gets to you after a while!) and this means that the amplitude of over 11V peak-to- peak is larger than it would be. With the speaker connected the amplitude drops to between 6V and 9V peakto-peak, depending on the frequency setting. OK, now let’s have look at IC1. This is almost identical to the circuit for IC2 except that the capacitor at pins 2 & 6 is 47µF instead of 0.1µF. This means that the frequency range will be about 500 times lower. Fig.6 shows the waveforms at pin 2 and pin 3 of IC1. The upper trace shows the sawtooth or triangle waveform at pin 2. The frequency can be made to vary between about 0.5Hz and 2.8Hz, depending on the setting of pot VR1. Actually, the waveform at pin 2 looks more “sawtoothy” at the low Fig.2: in this circuit, IC1 is used as monostable and it allows IC2 to produce a burst of oscillation lasting for about one second. If you want it longer, increase the 47µF capacitor at pin 6. October 2000  61 Fig.3: this shows the Protoboard component layout for the siren circuit of Fig.1. Note that you can build the circuit in stages, starting with the parts for IC2 (see text). frequency setting of VR1, with a long upslope and then a relatively sudden down-slope. We use the sawtooth waveform from pin 2 of IC1 to modulate the frequency of IC2. Hence, pin 2 of IC1 is connect­ed via a 10kΩ resistor to the CV (control voltage) input, pin 5, of IC2. This causes the internal thresholds of the 555 window comparator to be moved up and down. The result is that IC2’s frequency jumps up with each downslope of the sawtooth and then falls away, just like a wailing siren. Fig.7 is an attempt to show this modulation effect but the digital scope can’t really give a true picture because its time­base speed of 100ms/ The completed Siren circuit, viewed from the front. The two potentiometers (VR1 & VR2) are fitted to holes in the front panel at top left. 62  Silicon Chip div (to display the sawtooth) is far too slow to show the siren frequency (lower trace). OK, we have just about covered all the waveforms that you can check on this modulated siren circuit but there are still a few wrinkles to uncover. First, disconnect the 10kΩ resistor from pin 5 of IC2; just plug the unused end into one of the unused Protoboard boles. Now IC2 is unmodulated and produces a steady tone. Want to make it louder? There are two ways. First, you can reduce the value of the 68Ω resistor in series with the loudspeaker. This will allow more current through the speaker but is not the most efficient way. Second, try mounting an empty toilet roll over the speaker and then “tune” VR2 for maximum loudness. You can have quite a lot of fun with this effect. Finally, you might wonder why we bothered putting a 100µF coupling capacitor in series with the speaker. Why have it there when the circuit will work without it? If you don’t believe us, try shorting the capacitor out. Still works, doesn’t it? But notice that Fig.4: this is the waveform at pin 3 of IC2 in the circuit of Fig.1. It has negative pulses which are 700µs wide at a repeti­tion rate of 200Hz. Fig.5: this shows the same circuit conditions as at Fig.4 but VR2 has been set to increase the pulse repetition rate to 675Hz. Fig.6: these are the waveforms at pin 2 and pin 3 of IC1 in the circuit of Fig.1. The upper trace shows the sawtooth or triangle waveform at pin 2. The frequency can be made to vary between about 0.5Hz and 2.8Hz, depending on the setting of pot VR1. The lower trace is the negative pulse train; the pulse width is about 38ms. Fig.7: these waveforms attempt to show the modulation effect of the circuit of Fig.1. The digital scope can’t really give a true picture because its timebase speed of 100ms/div (to display the sawtooth) is far too slow to show the siren frequency (lower trace). Fig.8: this scope shot shows the current waveform through the 68Ω resistor and loudspeaker when the 100µF capacitor is shorted out. The ampli­tude is 3.76V peak-to-peak. Fig.9: this shot shows the current waveform through the loudspeaker and 68Ω resistor when the 100µF capacitor is in circuit. Note that the peak-to-peak and RMS current values are substantially higher than in Fig.8. October 2000  63 of Fig.2, the timed alarm. Pin 4 of IC2 now goes to pin 3 of IC1 instead of to the +9V line. The 10kΩ resistor bet­ween pin 2 of IC1 and pin 5 of IC2 is removed. Also, pin 2 of IC1 now goes to a pushbutton instead of to pins 6. This converts IC1 from a low frequency oscillator (ie, an astable) to a pulse generator (ie, a monostable). Bursts of sound This rear view shows how the completed is connected to the DC socket, the pots (VR1 & VR2) and the loudspeaker using flying leads. it is not as loud as with the capacitor doing its job? Now why is that? We’ll give you a hint. With the capacitor out of circuit, the 555 only “sources” current into the loud­speaker when its output at pin 3 is high. So we get a train of positive pulses through the speaker. But when the 100µF capacitor is in series with the speaker, current can flow in two directions: first, when pin 3 is high, it charges up the 100µF capacitor via the 68Ω resistor and speaker and second, when pin 3 is low, it then discharges the 100µF capacitor via the resistor and speaker. So we get more drive to the speaker. To prove it, we used the scope again. Fig.8 shows the cur­ rent waveform through the 68Ω resistor when the 100µF capacitor is shorted out. The amplitude is 3.76V peak-to-peak. Then, when the capacitor is back in circuit, the frequency remains the same, as you would expect, since the output loading has no effect on the frequency of a 555 oscillator. But note that the amplitude is now almost doubled, in Fig.9. It sounds quite a lot louder too. Timed alarm Now that you’ve had fun with the siren, let’s change the circuit to that Fig.10: this shows the burst effect that can be obtained with the circuit of Fig.2 (see text). 64  Silicon Chip Actually, as part of the change, you can leave the pushbut­ton out of circuit for the moment and just connect pin 4 of IC2 to pin 3 of IC1 (leave pin 2 connected to pin 6). Now if you apply power, IC1 will cause IC2 to produce bursts of sound from the speaker at a rate which can be varied by VR1. Fig.10 shows the effect. If you want the timed burst to be longer, you can increase the value of the 47µF capacitor at pin 6 of IC1 and VR1 can be increased in value. How the circuits work After all that, you probably have nutted out how each of the circuits work but we will go through it briefly for the sake of completeness. Apart from the timed alarm circuit of Fig.2 where IC1 works as a mono­ stable, all the circuits work as astable multivibrators. The resistors and pot­entiometer at pins 2 & 6 charge the capaci­ tor (0.1µF or 47µF) up to two-thirds of the supply voltage wher­e­upon the internal transistor at pin 7 discharges the capacitor down to one-third of the supply voltage. The one-third and two-thirds voltage thresholds are set internally for the 555’s window comparator. While the capacitor at pin 6 is charging, the output at pin 3 is high and while it is being discharged, the output is low. You can check this effect on the various scope waveforms in this article. Pin 4 (RESet) is normally tied high and if it is low it inhibits oscillation. We use this fact in the timed alarm of Fig.2. Pin 2 is normally tied to pin 6 in the astable oscillator circuit but is used in the timed alarm as the trigger input for the monostable circuit. Pulling pin 2 suddenly low starts the monostable; pin 3 goes high while the capacitor at pin 6 charges and then goes low when it reaches two-thirds SC of the supply vol­tage. VALVE BOOKS AT PRE-GST PRICES We pay the GST!! 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Send SSAE for complete catalogue of valves, books, sockets and capacitors. EVATCO ELECTRONIC VALVE AND TUBE COMPANY PO Box 487, Drysdale, VIC 3222 Tel: (03) 5257 2297 Fax: (03) 5257 1773 Mob: 0417 143 167 email: evatco<at>mira.net October 2000  65 WARNING This fuel mixture display should not be regarded as an accurate instrument since it will not necessarily be tailored to suit the voltage vs. lambda output curve for the particular oxygen sensor it is monitoring. To set the unit up as a calibrated instrument would require comparison with a known reference and subsequent adjustment of the internal software lookup table which converts the measured voltage into an air/fuel ratio. As published, the air/fuel mixture display is designed to follow the Bosch 0258104002 sensor output characteristics but even then, the calibration procedure will give approximate results only. Other typical narrow-band sensors can vary quite a lot in their output characteristics away from stoichiometric and, like the Bosch unit, also vary substantially in output voltage depending on temperature. For this reason, the Air/Fuel Ratio Meter is intended only for use as a dashboard unit to indicate air-fuel ratio trends during driving. It should not be relied on as an accurate instrument for tuning programmable engine management systems on a dynamometer or for making other engine adjustments. Part 2: final assembly, installation & calibration Mixture Display Last month, we described the circuit for the Fuel Mixture Display and showed you how to build the PC boards. This month, we complete the assembly and describe how the unit is installed and calibrated. By JOHN CLARKE Work can now begin on the case. First, remove the integral side pillars using a sharp chisel, then slide the microcontroller PC board in place and drill two mounting holes – one through the metal tab hole of the regulator and the other at bottom left, below the 0.1µF capacitor. These holes should be countersunk on the outside of the case (use an oversize drill to do this), if you intend using countersunk screws. Two holes are also required in the 66  Silicon Chip rear of the case (near the bottom) to accept the supply and sensor leads. The front panel label can now be affixed to the case lid and used as a template for making the display cutout and for drilling the hole for the LDR. The main display cutout is made by drilling a series of small holes right around the inside perimeter, then knocking out the centre piece and filing the job to a smooth finish. Make the cutout so that the red Perspex or acrylic window is a tight fit. Once it’s in place, the window can be further se­cured in place using several spots of super glue on the inside edges. Testing Before installing the micro­ con­ troller (IC1), it’s advisable to check that the regulator circuit is working correctly. This test is carried out on the micro­ controller board only; ie, the display board should not be plugged in. To check the regulator, connect automotive leads to the +12V and GND terminals, apply power and check that there is +5V on pins 4 & 14 of IC1’s socket. The metal tab of REG1 can be used as the ground connection during this procedure. If the +5V supply rail is correct, disconnect the power and install IC1 with pin 1 positioned as shown. The display board can then be plugged into the microcontroller board and Fig.4: this diagram shows how the two boards are stacked together and secured using screws, nuts and brass spacers. Notice that the righthand brass spacer is 9mm long, while the lefthand one is just 6mm long. Fig.5: the full-size front panel artwork is reproduced above, while at right are full-size etching patterns for the two PC boards. the assembly secured as shown in Fig.4. Check that there are no shorts between the two boards – some of the pigtails on the display board may have be trimmed to avoid this. Once the assembly is complete, reapply power with the EGO signal lead connected to ground. The display should light and show either an “L” (for Lean) or a high value (ie, a high air-fuel ratio). You can test the dimming feature by holding your finger over the LDR. Adjust VR1 until the display dims. This trimpot is best adjusted in the dark to obtain the desired bright­ness. You will need a 1V voltage source to set the span control, VR2. This can be derived from either a variable power supply or from a battery. Either way, you may need to divide the available voltage down so that your digital multimeter shows exactly 1V. Perhaps the easiest way to do this is to connect a trimpot (or a potentio­ meter) across the power supply or battery and adjust the wiper until there is 1V between the negative terminal and the wiper. The pot should have a value of between 1kΩ and 100kΩ and, if you are using a variable power supply, this should be adjusted to Adjustment Switch off the power and adjust trimpots VR2 and VR3 to their centre positions. This done, solder a 1.8kΩ resistor (R2) to the copper side of the microcontroller PC board, between pin 9 of IC1 and the copper area beneath REG1 – see Fig.6. Next, connect the sensor input to ground and apply power. The display should show a reading which is close to 0.00 or it should show a “-” sign, indicating a negative value. Adjust VR3 until the display shows 0.00V. Note: adjust VR3 anticlockwise if the reading is above 0.00 and clockwise if it shows a “-”. The whole assembly fits neatly into the smallest available plastic utility box and matches several previous car projects based on PIC microcontrollers. LDR1 should be mounted so that its face is about 3mm above the LED displays. October 2000  67 This view shows one of the EGO sensors in a Holden VT Commodore. The VT’s engine has two sensors – one for each cylinder bank. You can use either. provide a low output voltage – eg, 5V or less – before the pot is connected. Alternatively, you can simply divide the 5V supply at the output of REG1 down to 1V using a pot, as described above. Now apply this 1V between the sensor input and ground and adjust VR2 until the display shows 10.0. This represents a vol­tage reading of 1.00V; ie, the decimal should be in the wrong place. This adjustment ensures that the unit operates over the standard 1V range provided by the EGO sensor. You may now wish to recheck the offset adjustment when the sensor The Suzuki Vitara’s EGO sensor is easy to find. This, by the way, is a 4-wire sensor – two for the heater, one for the signal and the other for the ground return. Fig.6: resistor R2 is installed to convert the unit to voltage mode so that the offset voltage can be correctly adjusted. Once the adjustment has been made, the resistor is removed. R3 is required if your engine runs on propane and is left out for unleaded petrol. input is connected to ground again – if it’s out, simply tweak VR3 for a 0.00 read­ing. When these adjustments have been completed, remove resistor R2 so that the display now shows the mixture ratio. Finally, if you are using propane (or LPG) instead of un­leaded petrol, you will have to install R3 as shown in Fig.6. Installation The Fuel Mixture Display can now be installed in the vehi­cle. Use automotive connectors and cable to make the +12V and GND (ground) What’s Inside An EGO Sensor? There are two types of oxygen sensor in general use, the first based on zirconium oxide (or zirconia, ZRO2) and the second based on titanium oxide. The zirconium oxide type is the most common as it generates a direct output voltage. These sensors are also often called Lambda (λ) sensors. Lambda is simply the current air-fuel ratio divided by the air-fuel ratio at stoichiometry. Its value is 1 at the stoichiometric point, is greater than 1 when the mixture is lean and less than 1 when the mixture is rich. Fig.7 shows the cross section of a typical zirconia EGO sensor. It uses a thimble-shaped section of zirconia with platinum electrodes attached on the inside and outside. One electrode is exposed to the at­ mosphere while the other electrode is exposed to the exhaust gas. 68  Silicon Chip Fig.7: cross-section of a typical zirconia EGO sensor. The EGO sensor generates a voltage due to the differing concentrations of oxygen ions at either electrode. Oxygen ions are negatively charged and the zirconia has the tendency to attract these oxygen ions and they accumulate on the surface of the electrodes. The electrode exposed to air has a greater con­centration of oxygen compared to the electrode exposed to the exhaust and so it becomes electrically negative. In practice, the negative electrode is connected to chassis and the exhaust electrode is positive. The magnitude of the voltage depends on the concentration of oxygen ions in the ex­haust gas and the temperature of the sensor. connections. In particular, note that the +12V supply must be derived via the ignition switch and a suitable connection point will usually be found inside the fusebox. Be sure to choose the fused side of the supply, so that the existing fuse is in series. The ground connection can be made to the chassis using an eyelet and self-tapping screw. Note that, for best results, this ground connection should be made at a point close to the EGO sensor ground which is on the exhaust manifold. The sensor input wire connects to the EGO output wire. Sensor connection Oxygen sensors are commonly available in single or 3-wire configurations. If your car has a single-wire sensor, you simply connect the lead from the Fuel Mixture Display directly to the sensor output terminal, along with the existing lead to the engine management computer. To do this, first push a pin through the centre of the lead and bend the ends over. You can then solder the lead from the Fuel Mixture Display to this pin and wrap the joint in insulation tape. In the case of a 3-wire type of sensor, two of the leads are used to power an internal heater. These two leads are easy to identify, since one will be at +12V when the ignition is turned on and the other at 0V. The sensor lead will have a voltage somewhere between 0V and 1V, as measured on a high-impedance (ie, digital) multi­ meter, and the lead from the Fuel Mixture Display connects to this. Now start the engine and check that the display shows various readings from rich to lean. However, don’t expect the rich end of the display to light up until the EGO sensor has warmed up, even though the mixture is rich during the warm-up period. The EGO output is temperature dependent, which means that it must reach operating temperature before giving correct EGO indication. Once the engine is warm, the display should show the air-fuel ratio, while the bargraph should show the current trend (ie, the LEDs should move up and down the display as the mixture ratio varies). The display should show a rich (ie, low air-fuel ratio) reading or even an “r” (for rich) when using full throttle. Parts List 1 microcontroller PC board, code 05108001, 79 x 50mm 1 display PC board, code 05108002, 78 x 50mm 1 front panel label, 80 x 51mm 1 plastic utility case, 83 x 54 x 30mm 1 Perspex or acrylic transparent red sheet, 56 x 20 x 3mm 1 4MHz parallel resonant crystal (X1) 1 LDR (Jaycar RD-3480 or equivalent) 3 PC stakes 3 7-way pin header launchers 2 DIP-14 low-cost IC sockets with wiper contacts (cut for 3 x 7-way single in-line sockets) 1 9mm long x 3mm ID untapped brass spacer 1 6mm long x 3mm ID untapped brass spacer 2 6mm long M3 tapped spacers 2 M3 x 6mm countersunk screws or Nylon cheesehead 2 M3 washers 1mm thick or 1 M3 nut 2mm thick 2 M3 x 15mm brass screws 1 2m length of red automotive wire 1 2m length of yellow automotive wire 1 2m length of black or green automotive wire (ground wire) 1 500mm length of tinned copper wire for links Semiconductors 1 PIC16F84P microcontroller with AIRFUEL.HEX program (IC1) Conversely, if the throttle is abruptly lifted the reading should be high (lean) or should display an “L”. Calibration Unfortunately, it’s not possible to accurately calibrate the unit unless you have access to a known reference (see panel). However, the readings should be roughly “in the ballpark”, provided the unit is used with a 0-1V EGO sensor and VR2 & VR3 are adjusted as described previously. If necessary, you can adjust the calibration to suit the sensor on a trial and error basis. Adjust VR2 clockwise 1 LM358 dual op amp (IC2) 1 7805 5V 1A 3-terminal regulator (REG1) 4 BC327 PNP transistors (Q1-Q4) 2 BC337 NPN transistors (Q5,Q6) 3 HDSP5301, LTS542A common anode 7-segment LED displays (DISP1-DISP3) 1 10-LED red vertical bargraph (Jaycar Cat ZD-1704 or equiv.) 1 LM336-2.5 reference diode (REF1) 1 16V 1W zener diode (ZD1) 2 1N914 diodes (D1,D2) Capacitors 1 47µF 16VW PC electrolytic 3 10µF 35VW or 63VW PC electrolytic 4 0.1µF MKT polyester 2 15pF ceramic Resistors (0.25W 1%) 1 1MΩ 2 1.8kΩ 1 180kΩ 2 1kΩ 1 100kΩ 1 1kΩ 0.5W 1 12kΩ 4 680Ω 1 10kΩ 8 150Ω 2 3.3kΩ 1 10Ω 1W Potentiometers 1 500kΩ horizontal trimpot (VR1) 1 250kΩ horizontal trimpot (VR2) 1 20kΩ horizontal trimpot (VR3) Miscellaneous Automotive connectors, heatshrink tubing, cable ties, etc. if you want rich mixture indication to occur at a lower sensor voltage, for example. Similarly, adjust VR3 anticlockwise if you want lean readings at a higher sensor voltage. You may also wish to reduce the amount of display movement, particularly on the bargraph display. This can be done by in­creasing the value of the 0.1µF capacitor on pin 2 of IC2a. You can use an MKT style capacitor up to 1µF or a low leakage elec­trolytic from 1µF up to 10µF. The positive side of the capacitor should go towards the SC EGO input terminal. October 2000  69 Drive By Wire The Bosch ME-Motronic System; Pt.2 Last month, we covered the unique hardware associated with this new engine management system which eliminates the accelerator cable and thereby any direct link between the driver and the throttle. In this story we explore some of the control system logic. By JULIAN EDGAR As discussed last month, the Bosch ME-Motronic engine man­ a gement system is a radical departure from current systems which control fuel injection and ignition timing. The relationship between the accelerator pedal position and the opening angle of the throttle valve is no longer fixed - there is no accelerator cable. Instead the Electronic Control Unit (ECU) determines how much engine torque is required and then opens the throttle valve to the appropriate angle. The chosen throttle opening is based on complex software that models the engine’s instantaneous torque 70  Silicon Chip output and compares this with the required torque output, as requested not only by the driver but also by other in-car systems. Torque control logic The ME-Motronic system coordinates the various torque de­mands in order that it can implement an overall torque control strategy. Torque requests are categorised as “Internal” or “External”. External torque requests include those made by the driver, cruise control system and driving dynamics systems like Automatic Stability Control. Internal torque requests are those made by the internal programming of the ECU - factors such as engine governing and idle speed control. The total requested torque is then modified by factors such as catalytic converter temperature or driving smoothness. Fig.1 shows an overview of this approach. In previous engine management systems, the driver operated the throttle and thereby had direct control over the mass of cylinder charge, while the management system was limited to torque reduction strategies (eg, by fuel cuts) or minor torque increases through manipulation of the mass of air bypassing the throttle. However, this approach does not cope very well with competing and contrary torque demands that may well occur simul­ taneously. Fig.2 shows some of the required torque variations found in current cars, excluding those requested by the driver. The ME-Motronic system internally models the net torque development of the engine. This model takes into account losses through internal friction, pumping losses and parasitic Fig.1: unlike a conventional management system, in the ME-Motronic system there are multiple torque request inputs, rather than a system that indirectly responds to the driver’s request by sensing increased intake airflow or changes in mani­fold pressure. The driver and external systems make the External Torque Requests, while the Internal Torque Requests are pre-programmed internal ECU factors. Actual developed torque is determined by control of the throttle valve angle, intake charge pressure (turbo cars), ignition advance angle, injection cut and injection pulse width. [Audi] loads such as that of the power steering and water pumps. Internal mapping within the ECU allows optimum charge density, injection duration and ignition timing for any desired net torque value, taking into account best fuel economy and exhaust emissions. These often conflicting requirements dictate that the system must perform well in transients, as well as when being subjected to steady-state loads. To allow good performance in both constant and transient load conditions, two different con­ t rol approaches are taken. Bosch call the first control strategy the “Charge Path”. “Charge” in this context refers to the density of air trapped in the cylinder. At a given air/ fuel ratio and ignition advance, the mass of this air is directly proportional to the force generated during the combustion process. The Charge Path, controlled by the opening angle of the throttle valve (and boost pressure in a super-charged or turbo-charged car), is used to control engine torque output in static operations. The dynamic nature of this control is limited by the regu­lating speed of the throttle actuator and the time constant of the intake manifold, which can be as high as several hundred milliseconds at low engine speeds. The other technique used to control torque output is called, somewhat oddly, the “Crankshaft Synchronous Path”. This refers to torque variations able to be rapidly created by changes in ignition timing and injection operation, with the latter used to effect the air/fuel ratio. Examples of when this approach is employed include torque reduction during automatic transmission gear changes and when Traction Control systems are operating. Getting confused? Fig.3 puts all of this together. On the far left is the driver, who (at least on the diagram!) is still given pride of place. The driver’s torque request is processed in terms of driveability functions and given a priority level; ie, the driver may not get what he requested! Some of the driveability functions include filtering and slope-limiting, dashpot (to ensure that torque changes do not occur too quickly) and anti-jerking. These functions can be calibrated to suit a wide range of applications – for example, a high level of anti-jerk to suit a luxury car or a very quick throttle response to suit a sports car. The BMW M5 V8 has a switch that allows selection of ‘sport’ or ‘normal’ throttle modes. In addition to the driver’s torque October 2000  71 Fig.2: all the torque demands on the engine are assessed and given a priority before the ECU decides on an appropriate throt­tle opening angle to use. In addition to the request of the driver, there are a variety of requests that may need to be processed before the final decision is made. [Audi] request, other torque variations (for example, an increase in torque to operate the air conditioner compressor or a reduction in torque required by the load change damping system) are processed, with the final request then fed into the ‘Torque to charge density conversion’ box. When a torque request is made, the ECU must calculate how much fresh air mass is required to be inhaled by the engine to meet this demand. The actual mass of air that is needed will be dependent on ignition timing (eg, if the engine is running rela­ tively retarded ignition to decrease oxides of nitrogen emis­sions, more air will be needed because efficiency will be lower), internal engine friction, the instantaneous air/fuel ratio and other factors. Once a mass airflow that will meet the requirements is worked out, a throttle valve opening angle is calculated. Howev­er, in all engines, the required angle will be dependent on The ME-Motronic ECU uses tiny surface mount components, with the board very similar in appearance to this Alfa Romeo ECU. 72  Silicon Chip the manifold pressure and in forced aspirated engines, manifold pressure will be quite critical to the mass of air actually inhaled. In these engines the turbocharger boost pressure and throt­ tle valve opening are both specified such that the appropriate charge density required for the prescribed torque output is reached. Calculating cylinder charge As can be seen from the above, the accurate calculation of cylinder charge is vital if the torque modelling strategy is to be effective, and if appropriate amounts of fuel are to be accu­rately added to this air. Traditionally, a mass airflow meter positioned between the air filter box and the throttle body has been used to measure intake airflow. However, engines are now taking advantage of techniques that maximise cylinder charge such that an averaged mass airflow measurement may not be sufficiently accurate. In the ME-Motronic system the available sensors are used as inputs to a charge air model, rather than being evaluated direct­ly. The requirements for such a charge air model are: • Accurate mass charge air determination in engines using reso­nant tuned and/or variable length intake manifolds, and engines using variable valve timing; Fig.3: two different decision making paths are used to specify the actual engine torque that is delivered. The upper path on the diagram shows how the entrance of the appropriate mass of air into the cylinders is determined, while the lower path controls torque via fuel and ignition changes. [Bosch] • Accurate response to Exhaust Gas Recirculation conditions; • Calculation of required throttle valve aperture (and required turbo boost in forced induction engines). While the engine is subjected to a constant load, mass airflow measurement is relatively accurate; ie, if Xkg of air per second is passing through the airflow meter, it can be assumed that all of it is ending up in the cylinders. However, during transients such as rapid use of the throt­tle, the situation is much more complex. If the throttle valve is abruptly opened, the intake plenum chamber will rapidly fill with air. For an instant, the airflow meter will indicate a higher cylinder charge than has actually had time to occur. It is only when intake manifold pressure has risen that the flow will com­mence into the cylinders. As a result of this characteristic, the ME-Motronic system generally uses both manifold absolute pressure (MAP) and hot wire airflow meter (HFM) inputs. (In some cases the MAP sensor is not fitted; further software modelling duplicates its function.) The HFM is a further development of the design used by management systems for about 15 years. Its improvements result in better accuracy. For example, it is capable of differentiating reverse flow pulses from air- flow (eg, in resonant inlet mani­folds) passing into the engine. Conclusion The Bosch ME-Motronic system represents a major change in management systems – very likely, it is as great a change as the combining of fuel injection and ignition timing controls into one system in 1979. Instead of the management system simply respond­ i ng to the engine load changes indicated by varying intake air­flows or RPM and manifold pressures, the control architecture now revolves around assessing the 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, setting up computer networks, hard disk drive upgrades, clean installing Windows 98, CPU upgrades, a basic introduction to Linux plus much more. instantaneous torque requirements. How the engine goes about fulfilling that requirement is now very largely determined by the ECU. Footnote: in the introduction to part 1 of this article, we stated that the Bosch ME-Motronic is the first drive-by-wire engine management system for cars. This is incorrect as some cars (eg, Lexus and BMW) have had drive by wire (ie, electronic throttle control) for some years. The ME-Motronic’s unique­ness comes from its variable relationship between accelerator pedal movement SC and throttle blade opening. www.siliconchip.com.au SILICON CHIP’S 132 Pages $ 95 * 9 ISBN 0 95852291 X 9780958522910 09 09 9 780958 522910 COMPUTER OMNIBUS INC LUD ES FEA TUR E LIN UX A collection of computer features from the pages of SILICON CHIP magazine o Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NTAVANOW DIRE ILABLE C SILIC T FROM ON just $ CHIP 125O INC RT 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. P&P October 2000  73 PRODUCT SHOWCASE Jaycar’s Catalog on CD-ROM A few months after releasing their all-new 2000/2001 catalog through SILICON CHIP, Jaycar Electronics have released it in electronic format on CD-ROM. The new catalog contains virtually the same product range of the printed version but has the advantage of much more economic updates. The catalog opens in its own browser window and is driven in much the same way as any other web page. Jaycar’s Managing Director, Gary Johnston, said that there would al- Suspect Cables? TestUm! There's nothing quite so frustrating as a suspect cable – especially when it’s a multi-strand cable such as Cat5. This microprocessor-controlled TP200 Twisted Pair Tester from Tel-ephone Technical Services is certain to gladden the heart of any network administrator, installer or technician. It’s delightfully simple to use and tests a variety of cable faults – shorts, opens, miswire, reversals, split pairs and so on. It sells for under $150 including GST. Contact: Telephone Technical Services 2/55 Shore St, West Cleveland Qld 4163 Phone: (07) 3286 6388 Fax: (07) 3286 6399 74  Silicon Chip ways be a big demand for the printed catalog but his company also sees the CD-ROM version becoming more and more popular. “While we still believe that nothing quite beats the pleasure of browsing through a printed catalog, the enhanced search facilities of the new CD-ROM will be of tremendous benefit to those customers who need to find a specific product in a hurry,” he said. “Like the printed version, all products have colour photographs and as much information as we could fit. But more importantly, we’ve been able to include a number of datasheets and guides which would not fit in the printed catalog.” Because the CD-ROM version of the catalog is database driven, the very latest and current pricing, models and availability will always be available via the Jaycar website (www.jaycar. com.au). Copies of both the printed and CDROM Jaycar catalogs are available at any Jaycar store – the printed catalog costs $2.95 and the CD-ROM version $2.50. Contact: Jaycar Electronics PO Box 185 Concord NSW 2137 Phone: (02) 9743 5222 Fax: (02) 9743 2066 Email: techstore<at>jaycar.com.au Website: www.jaycar.com.au Tektronix digital scope modules from Emona Two new modules, the TDS3TMT and TDS3EM, are available for the TDS3000 Tektronix Digital Phosphor Oscilloscopes. The first is for testing digital network interface cards up to 45Mb/s, to test E1/DS1, E3/DS3 standards called out in ITU-T G.703 and ANSI T1.102 as well as user customized variations. The TDS3TMT application module adds to the suite of application modules currently available for the TDS3000 DPO including Extended Video, Advanced Triggering, and Fast Fourier Transform (FFT). Accessories for mask testing are available including proper termination adapters for connecting to telecommunication line cards and a rack mount kit. The TDS3EM Ethernet module provides the ability to use and remotely control their TDS3000 DPO over a 10BaseT Ethernet connection and can now print directly to a network printer. The TDS3EM Ethernet module adds to the list of communication technologies currently available with the TDS3000 DPO including GPIB, VGA Output, and RS-232. Tektronix’ variety of ap- plication modules, communication modules, accessories, and software provides the flexibility to configure the TDS3000 DPO to provide a complete solution for a variety of test and measurement applications. Contact: Emona Instruments Phone: (02) 9519 3933 Fax: (02) 9550 1378 e-mail testinst<at>emona.com.au Ricoh’s new $999, 3megapixel digital camera The release of the $999 Ricoh RDC6000 digital camera makes top quality digital photography affordable. It’s lightweight (220g) and compact (110 x 67 x 39.5mm) yet offers a high resolution mode equivalent to three million pixels. The camera supports both PAL and NTSC and has both an optical viewfinder and LCD monitor, built-in flash, flexible white balance setting and a variety of software for data transfer and manipulation to a PC. This includes PhotoImpression, PhotoMontage, VideoImpression and PhotoFantasy. USB and serial cables, a lithium ion battery and an AC adaptor/ charger make up the pack. It can be used as a still camera or a a video camera and, with its USB port connection, a real-time Web camera. It is supplied with an 8MB SmartMedia memory card (which can store up to 198 images or 72 seconds of motion pictures). With the optional 64MB card, 1690 images can be stored or 626 seconds of motion. An optional remote control unit is also available. The new Ricoh is available now from leading photographic and computer stores around Australia. Contact: Ricoh Phone: (02) 8977 1411 or: (03) 9888 7722 Website: www.ricoh-aust.com.au Non-olympic relays from Altronics Mention the word “relay” at the moment and everyone thinks of that other type. So Altronics thought it the perfect time to introduce (or re-introduce) their range of PCB-mounting relays to the world. There are several in the mains-rated series – shown here are the new 8A DPDT and 12A SPDT low profile models with either 12V [8A S4270, 12A S460] or 24V [8A S4272, 12A S4262] coils and some popular models, the 5A SPDT relays (also with 12V [S-4202] and 24V [S4204] coils). The latter relays are fully sealed – in fact, they can be cleaned by full immersion. Current rating is at 240V AC and can be doubled for 24V DC. Insulation resistance of all models is better than 100MΩ <at> 500V DC and Contact: Altronics Distributors Phone: (08 ) 9328 2199 Fax: (08) 9328 4459 email: mailorder<at>altronics.com.au Website: www.altronics.com.au STEPDOWN TRANSFORMERS 60VA to 3KVA encased toroids Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 Another new DSE PowerHouse Dick Smith Electronics have opened their seventh PowerHouse store at the corner of Church St and James Ruse Drive, North Parramatta in Sydney’s western suburbs. Over 30,000 products are featured. At 2000 square metres it’s about six times the size of an average DSE store. “Everything at a DSE PowerHouse is plugged in, powered up and fully tuned for customers to try out,” said Jeff Grover, DSE Managing Director. the relays are rated for an electrical service life of 100,000 operations minimum. Prices start at $3.15 for the 5A models, $8.35 for the 12A models and $10.45 for the 8A DPDT models. All prices include GST and generous quantity discounts are offered. Further information about this series of relays can be found in the Altronics 2000/2001 catalog (distributed free in SILICON CHIP in August) or at an Altronics store or dealer. October 2000  75 Low-cost motherboards from Oatley Electronics Looking for a cheap motherboard to upgrade an old computer or perhaps to build one from scratch? Oatley Electronics current­ ly have two different types for sale, both unused and priced at $90. Not only that, but if you order before the end of November 2000, they’ll chuck in a shrink-wrapped package of IBM’s “Voice­ Type 3.0” voice dictation software (OK, so it’s not the latest version but you get it as a bonus). Let’s look at the two mother-boards. The first offering is a Socket 7 motherboard with an AT form factor and integrated sound and video cards. This board is capable of supporting Intel Penti­um processors (both standard & MMX) from 100233MHz; AMD K5/ K6/K6-2 & K6-3 processors from 133-533MHz; IDT WinChip C6-200 and C6-225 processors; and IBM/ Cyrix processors from 150-400MHz. Strangely, the ma nua l do e s n’t directly show the settings in its processor tables for the AMD K6-2 450MHz or the K6-2 500MHz chips, even though the jumper settings allow for these proces­ sors. Similarly, the board should also cater for AMD K6-2 550MHz processors, since it’s capable of bus speeds up to 100MHz and multiplier settings can go to 5.5. Because it includes an integrated video card, there’s no AGP slot on the motherboard. Apart from that, all the expected features are there including two Ultra DMA66 IDE ports, two DIMM sockets for up to 256MB of RAM (EDO, BEDO or SDRAM), three PCI slots, an ISA slot, two USB ports and VGA and sound card connec­tors. The unit is supplied complete with all I/O cables (includ­ ing video and sound), the 76  Silicon Chip exception being for the USB sockets. The unit is supplied in an anti-static bag and comes with a manual and setup CD. In case you’re wondering, the board is made by PC Partner in Hong Kong, the model number is MVP4BS7-947 and there is a website that you can go to for BIOS upgrades. Check out www. pcpartner.com.hk This would be a great board for upgrading an early Pentium PC (eg, to an AMD K6-2) but be sure to set the jumpers to the correct core voltage for your chosen processor otherwise you’ll fry it. The second board is for Slot 1 Intel Pentium II and Celeron processors running at up to 800MHz on a 66MHz or 100MHz bus (ie, up to 8x multiplier settings). Branded as a “Merit M6TBA”, this board is made by Biostar (www.biostar-usa. com) and features three ISA slots, four PCI slots, an AGP slot and three DIMM sockets for up to 384MB of SDRAM. There are also onboard PS/2 keyboard and mouse sockets, two USB sockets, a parallel port socket and two serial port sockets, all arranged in standard ATX form. Other features of the unit include Award BIOS (updates available via LE the website), two Ultra DMA/33 IDE ports, an Intel BX chipset and a WakeOn-LAN header. Included in the original box are IDE & FDD I/O cables, a manual, a retention kit for the CPU, and a “Drivers & Utilities” CD. The sample unit we inspected also came with a rear I/O panel for an ATX case. The manual is quite detailed and includes lots of information on the BIOS setup. A similar Slot 1 Pentium II/Celeron motherboard designated “SP-6XS” is also available and is virtually identical in specifi­cation to the M6TBA. It too supports processors rated at up to 800MHz and supports bus speeds from 66MHz to 133MHz (CPU clock 66MHz or 100MHz). However, it only has two ISA slots compared to the Merit board’s three ISA slots and it features an SIS chipset. Oatley has advised us that the Merit motherboard will be supplied to customers until stocks run out, after which the SP6XS board will be supplied. By the way, if you’re looking for processor heatsink and cooling fans, Oatley Electronics have these available at very reasonable prices. The packs are all brand new and include a KTX Pentium II heatsink & fan for $4.50, a P6 heatsink & fan (for use with the Pentium Pro CPU) for $4.50; and a 586 heatsink & fan (for use with 486 & 586 CPUs) for $3.50. SC Contact: Oatley Electronics Pty Ltd PO Box 89, Oatley NSW 2223 Phone: (02) 9584 3563 Fax: (02) 9584 3561 website: www.oatleyelectronics.com.au 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. NEW! HC-5 hi-res Vi deo Distribution Amplifier DVS5 Video & Audio Distribution Amplifier Five identical Video and Stereo outputs plus h/phone & monitor out. S-Video & Composite versions available. Professional quality. For broadcast, audiovisual and film industries. Wide bandwidth, high output and unconditional stability with hum-cancelling circuitry, front-panel video gain and cable eq adjustments. 240V AC, 120V AC or 24V DC VGS2 Graphics Splitter High resolution 1in/2out VGA splitter. Comes with 1.5m HQ cable and 12V supply. Custom-length HQ VGA cables also available. Check our NEW website for latest prices and MONTHLY SPECIALS www.questronix.com.au Email: questav<at>questronix.com.au Video Processors, Colour Correctors, Stabilisers, TBC’s, Converters, etc. 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 QUESTRONIX All mail: PO Box 548, Wahroonga NSW 2076 Ph (02) 9477 3596 Fax (02) 9477 3681 Visitors by appointment only 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! MicroZed Computers GENUINE STAMP PRODUCTS FROM 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 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 October 2000  77 http://www.microzed.com.au Most Credit Cards OK Review by Ross Tester T he vast majority of audio equip ment available in Australia to day is imported. But there’s one Australian company which is determined to reverse that trend, at least in the public address area. Perth-based Altronic Distributors recently submitted one of their new Australian designed and manufactured Redback Phase 4 PA Mixer Amplifiers for our once-over. There are two models available, a 125W version and a 250W version which are apparently identical apart from the power. We received the 125 watt version. They say first impressions count and our first impressions were definitely favourable. If a PA Amplifier can be made to look good, Altronics have certainly succeeded. The amplifier is housed in a purpose-designed two-unit 19-inch rack mounting case, finished in matte black. And while the case is intended for rack mounting, it certainly doesn’t have to be used that way. They’re not lightweights: even the 125W model is around 12.5kg while the 250W version is a tad under 20kg. Case size is identical – 483 x 330 x 88mm. On the front panel are level controls for the six input channels which can be selected as 3mV balanced mic inputs (each with phantom powering) via 3-pin XLR sockets or as 200mV line or “aux” inputs via RCA sockets. (All inputs are on the rear panel). There is also a master volume control along with bass and treble controls (±10dB <at>10kHz and 100kHz respectively). There is also a LED bargraph VU meter, a large power switch and indicator LEDs showing power, peak level, fault condition and signal. On the rear panel are the input sockets previously mentioned, a “send/ receive” pair of RCA sockets which are preamplifier out and main amplifier in (these are normally bridged) Inside the Redback Phase4 PA Amplifier from Altronics. This is the 125W model – very clean inside and out. The “box” running left to right is in fact the fan-forced tunnel heatsink. The power amplifier itself is quite small, hidden by this heatsink. Top of shot is the input preamp, immediately below is the power supply module while the mixer PC board is virtually hidden under the lip at the front. 78  Silicon Chip and screw terminals for the amplifier output (4-16Ω and 70V/100V line) plus external power in (24V DC), PTT switched input and a VOX activated 24V DC output which can be used to power external relays (eg emergency sirens, self-closing doors, etc). There’s also mains input (via an IEC socket) and DC fusing. Inside the amplifier is a joy to behold: very nicely and cleanly laid out. In fact, for a moment we wondered where all the components were! The only PC boards immediately obvious were the main power supply board and the input preamps connected to the rear panel sockets on another Most of the inter-board wiring is done with IDC cable, á lá modern computers. The exception to this is power supply wiring and output wiring which is neatly laced together – all in all, a very professional package. One minor surprise was the use of a standard iron cored 100V output transformer while the power transformer was a (now almost conventional) toroidal type. This could be to get the power rating required in the 250W version which would require a much larger toroidal. The amplifier Output power is quoted at 125W can provide a trickle charge for 24V DC batteries. It also has input 1 priority and vox muting. Competitive price One of the biggest difficulties an Australian manufacturer faces is being able to keep prices at least on a par with the imports. Given the features of their amplifiers, Altronics have succeeded in making them more than competitive – they’re really good value. The 125W model (cat A1826) sells for $875 including gst, while the 250W model (cat A1836) sells for $1099 including gst. Both carry a five year manufacturer’s warranty. Popular On the left are the various power inputs and speaker outputs. Each of the inputs (right side) can be line or mic level, via RCA or Cannon connectors. board. The main power amplifier PC board is tiny – just 150 x 40mm – and is mounted on a long tunnel heatsink which lies transverse across the case. Also on this heatsink are two large bridges, one used as a rectifier while the other simply performs reverse-polarity protection when the unit is connected to 24V DC. An 80mm fan draws air from inside the heatsink and expells it through slots in the the front panel. One more board, containing the mixer components, lies almost hidden under a lip off the rear of the front panel. RMS, with frequency response (±3dB) of 50Hz to 15kHz at a total harmonic distortion of less than 0.5% at 1kHz. In terms of hifi, these aren’t particularly brilliant figures but this is not designed as a hifi amp – and for its purpose, those figures are more than satisfactory. Other “bells and whistles” include thermal overload and short circuit protection, along with a peak limited output. The fans only operate when required to and the availability of 24V DC powering (as well as 240V AC) means the amplifier can be used in “must work” situations such as emergency evacuation. The amplifier We first saw these amplifiers in the 1999 Altronics catalog and asked them several months ago if we could have a look at one. It was only quite recently, and after even more prodding, that they had just one spare unit to send us. According to Altronics’ Brian Sorenson, demand for these amplifiers has significantly outstripped the company’s ability to manufacture them. “Most of our orders are coming from the professional installation market,” he said. “Word has managed to get around very quickly about the Phase4 systems and we are even getting enquiries from offshore,” he said. “We’ve sent these amplifiers to New Zealand, the Pacific and even into Southeast Asia.” Now that is a coup: exporting Australian-made amplifiers to Asia! SC CONTACT: Altronic Distributors Pty Ltd; Perth, Sydney & Melbourne – (08) 9328 2199 October 2000  79   Own an EFI car? Want to get the best from it? You’ll find all you need to know in this publication       
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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 Spec i SUB al Offer SCR IBE & COM PUTE GET R OM FO N Aust R FREE! IBUS ralia Only* 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  81 Australia 2097 * Special offer applies while stocks last. 10-00 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG A battery eliminator, a servicing aid & getting the good oil A battery eliminator is virtually a must if you want to run battery-powered vintage receivers. This month, we take a look at the Monarch battery eliminator, describe a simple servicing stand for record turntables and tell you where to look for information on vintage radio. Almost from day one, battery eliminators were used to reduce the cost of running battery-powered radios. That’s because portable radios were so convenient that they were often used in the home as well as outdoors, but the cost of running a set on batteries alone was prohibitive. To overcome this problem, the radio manufacturers developed mains-powered battery “eliminators”. The Monarch BLK battery eliminator of 1947 is one such device and was a big improvement on the designs used in the 1920s. Monarch equipment was made by Eclipse Radio and family resemblances to Peter Pan and Astor can be seen. The Monarch’s nominal output voltages suits sets using 1.4V valves with 90V high tension (HT). Physically, it is about twice the size of two 45V batteries and it has just one control – an on-off switch. The unit, in its original form, had a 4-core lead and an octal plug on the end of the lead so that it could plug into the sets that it was designed to power. I decided that The Monarch BLK battery eliminator front panel is shown at left, while above shows the unit removed from the case. The D-size cell can be seen at top right and this functioned as a filter/regulator for the 1.4V rail. 82  Silicon Chip ELECTRONIC VALVE & TUBE COMPANY 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. Fig.1: circuit diagram of Monarch BLK Battery Eliminator. It used a power transformer with two secondary windings, one for the 90V HT rail and the other for the 1.4V rail (to supply the valve filaments). Note the lack of a mains earth, even though the device was built into a metal case (see text). I would use it as a general-purpose eliminator instead of one designed specifically for particular sets hence the unterminated wiring on the unit shown in the photos. To dismantle it, the control knob is first removed and the front panel sprung to remove it. After that, it’s simply a matter of undoing three screws so that the works can be removed from the case. As can be seen from the circuit diagram (Fig.1), the unit is quite simple and so the restoration is also simple. There are two secondary windings on the transformer – a high-voltage wind­ing to supply nominally 90V for the HT supply and a centre-tapped 6V (3V + 3V) winding to power the filaments and indicator lamp. The high-voltage winding employs a half-wave dry metal “Westalite” rectifier. The HT is filtered in the normal way using two electrolytic capacitors and a 1kΩ resistor and this is quite effective. The actual HT voltage developed depends on the current drain. With no load, it is around 115V. The designed maximum current drain is 20mA. It is much harder to filter and maintain a low tension rail of 1.4V, compared to a 90V rail. In this case, the CT trans­ former secondary winding drives a full-wave “Westalite” rectifier and this gives a no-load voltage of 4.1V which, if connected directly to the valve filaments, would blow them instantly. So how did the manufacturers get the voltage down to 1.4V? Well, they did it in a couple of ways which, by today’s stan­ dards, were rather crude. First, the voltage drop across the filter chokes at currents of 250400mA reduced the output voltage to somewhere near 1.4V. However, with such a wide current varia­tion available from the supply, the output voltage could still be much too high for the valve filaments and would burn them out. This meant that the output voltage had to be regulated in some way and this was done by switching a 1.5V “D” cell across the output when the unit was turned on. As a result, the filament voltage is held within tolerance. The cell also has another function – it acts as a large filter element so 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 Silicon Chip Binders REAL VALUE AT $12.95 PLUS P&P  Heavy board covers with 2-tone green vinyl covering  Each binder holds up to 14 issues  SILICON CHIP logo printed on spine & cover Price: $A12.95 plus $A5 p&p each (Australia 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. October 2000  83 through the cord-entry grommet – a common technique in those days. If you decide to restore this type of equipment, the mains cord should be replaced with a 3-wire type so that the metal case can be correctly earthed. In addition, the cord should be proper­ly secured using an approved clamp or cordgrip grommet. If you have any doubts about what you are doing, seek advice from someone who’s qualified. In summary, this little unit is a simple but effective battery eliminator from the early post WWII era. These days, of course, much more effective and versatile battery eliminators can be built, which have precise regulation at several nominated output voltages. What’s more, they will accurately maintain these output voltages over wide variations in the amount of current drawn. Servicing stand This is the underside view of the battery eliminator chassis. Note the knot in the mains cord to anchor it and the lack of earthing for the metal case (only a 2-wire mains cord was used) – two things that wouldn’t pass muster nowadays. A correctly anchored 3-wire mains cord with the earth lead connected to chassis is the next step in the restoration process and will greatly improve safety. that the filament supply is very close to pure DC. Monarch recommended that this “D” cell be replaced every 12 months. If the unit hasn’t been abused, all that will be necessary to do is check for hum on both the HT and LT supply lines. If a set connected to the supply hums, try replacing all the electro­ lytic capacitors with equivalent value units. In this unit, there are only four of them, so this is hardly an arduous exercise. If you have a digital voltmeter, switch it to an AC range and, with a capacitor of around 0.47µF in series with one of its leads, connect it across each of the DC supply rails in turn. In each case, there should be no readings on the meter after the 0.47µF series 84  Silicon Chip capacitor has been charged. On the 1.4V line, even the 10V AC range of a conventional moving coil meter is unlikely to register any hum voltage unless the filtering is completely ineffective. A digital meter has more chance of indicating if any hum is present. Electrical safety And here a note about electrical safety. By today’s stan­ d ards, this device certainly wouldn’t meet the safety requirements of electrical authorities. For starters, it was only fitted with a twin-core power cord which meant that the metal case wasn’t earthed. Second, the power cord was “anchored” by tying a knot in it inside the case, so that is couldn’t be pulled Last month, I described the restoration of an HMV Nipper­gram. In that column, I briefly mentioned that the changer mechanism was tested by mounting it on a “servicing board” (or stand) so let’s now take a closer look at this simple yet invalu­ able servicing aid. In order to check the operation of a record changer, it must be mounted horizontally and you must be able to view the mechanism underneath the frame while it is operating. This is not always easy to do and many’s the time I’ve laid on the floor with a torch shining on the works in an attempt to see how it all worked. This simple aid makes the job much easier. It consists of nothing more than several lengths of 9.5mm dowel and a 300 x 450mm piece of particle board (about 19mm thick) which is drilled to a grid pattern. The dowel pieces are “plugged” into appro­priate locations on the board and used to support the turntable at several points as shown in one of the photos. This makes it easy to inspect the mechanism as the turntable operates. If you want to make your own, drill the holes using a drill press (if possible) so that all they are perpendicular to the board. The holes are approximately 25 mm apart but don’t be too pedantic about that, as variable spacing will help fit the dowel ends between components on the changer or an upturned receiver chassis. Generally, four dowels will be enough to support any chassis or changer. I have four 300mm dowels for observing what’s going on with record changers and four 175mm dowels for mounting up­turned receiver chassis. In fact, a variety of dowel lengths can be cut to suit whatever you are servicing/restoring. The 9.5mm dowels are quite rigid and I don’t recommend using anything thinner as they can break too easily and your changer or receiver chassis could end up on the floor. To stop the mounted unit from moving around, I fitted a 6mm rubber chair tip to one end of each dowel. This involved machining (or filing and sanding) one end of each dowel piece to 6mm but the result is worth it. So there you have it – a simple lowcost device that will make servicing and restoring record changers just that bit easi­er. Getting the good oil How do vintage radio buffs get into this rewarding pastime of restoring radio and television equipment and collect­ i ng the paraphernalia that goes with it, such as books, posters, magazines and the like? My collecting started around 30 years ago. An advertise­ment appeared stating that a chap wanted to sell a military radio transceiver to someone who would restore it, before our radio history disappeared. That caught my attention, so I started collecting portable army transceivers from WWII. That’s how my collecting days started but how did yours? Perhaps this article is your first exposure to this interesting hobby. If you want to find out more, other magazines, both past and present, can be valuable sources of information. New magazines With the first burst of enthusiasm, it is likely that a new vintage radio enthusiast will grab just about anything on the subject and treat all that is said as gospel. Regrettably, some books and magazines are not really good sources of information and it is only when you become knowledgeable that you can sort the wheat from the chaff. It’s a bit of a catch 22 situation, really. Generally, American electronics/ radio magazines don’t offer a great deal for vintage radio enthusiasts in Australia and New Zealand. The main reason for this is that the American This simple servicing stand is invaluable when it comes to checking record changers but is also useful when servicing radio receivers. It allows you to inspect the mechanism of a record changer while it is operating. magazines cover 110V equipment and describe bits and pieces that are sometimes hard to obtain here. However, the various vintage radio groups in America do have their own publications and some of these are quite good. Sometimes, these are available through the Historical Radio Society of Australia (HRSA) or the New Zealand Vintage Radio Society (NZVRS). In addition, the HRSA and the NZVRS have their own respective in-house magazines – “Radio Waves” and the “NZVRS Bulletin”. These both concentrate heavily on vintage radio and are excellent for enthusiasts but you do have to be a member to obtain copies. On a similar theme, some of the vintage radio clubs in Australia (and probably in New Zealand too) have in-house news­letters. Old magazines Old radio/wireless magazines make very interesting reading and will give you an excellent feel for vintage radio. If you can get them, copies of “Wireless Weekly”, “Radio & Hobbies” and “Radio, Television & Hobbies” up to about 1965 are well worth collecting and reading. Of these, “Radio & Hobbies” probably provides the most relevant information for vintage radio enthusiasts. It also featured “The Serviceman Who Tells” column, which discussed the faults found in radios (and later, TV sets) in the period from 1939. These columns make good reading and now provide practical restoration tips. There were also many constructional articles, such as the “Little General” 4-valve radios, which I and many others found useful over the years. Finally, old magazines are particularly interesting because they trace the evolution of radio month by month. A lot of good stuff can be gleaned from SC their pages. October 2000  85 REFERENCE GREAT BOOKS FOR AUDIO POWER AMP DESIGN HANDBOOK NEW NEW NEW NEW INDUSTRIAL BRUSHLESS SERVOMOTORS By Douglas Self. 2nd Edition Published 2000 85 $ By Peter Moreton. Publ. 2000 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. VIDEO SCRAMBLING AND DESCRAMBLING for 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 TCP/IP EXPLAINED 99 AUDIO ELECTRONICS Satellite & Cable TV by Graf & Sheets Edition 1998 $ By John Linsley Hood. First published 1995. Second edition 1999. 65 $ 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 Philip Miller. Published 1997. $ 99 By Tim Williams. First published 1991 (reprinted 1997). $ LOCAL AREA NETWORKS: An Introduction to the Technology 65 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. ELECTRIC MOTORS AND DRIVES By John E. McNamara. 2nd edition 1996. By Austin Hughes. Second edition published 1993 (reprinted 1997). 69 $ 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. ESSENTIAL LINUX EMC FOR PRODUCT DESIGNERS 99 86  Silicon Chip 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. 65 $ By Steve Heath. Published 1997. By Tim Williams. First pub­­lished 1992. 2nd edition 1996. $ 85 $ THE CIRCUIT DESIGNER’S COMPANION 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. 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. 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. $ 85 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. BOOKSHOP WANT TO SAVE 10%? SILICON CHIP SUBSCRIBERS AUTOMATICALLY QUALIFY FOR A 10% DISCOUNT ON ALL BOOK PURCHASES! ENQUIRING MINDS! (To subscribe, see page 57) 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. By John Linsley Hood. First published 1993. NEW SECOND EDITION 1998. $ 88 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. DIGITAL ELECTRONICS – A PRACTICAL APPROACH By Richard Monk. Published 1998. GUIDE TO TV & VIDEO TECHNOLOGY By Eugene Trundle. First pub­­lished 1988. Second edition 1996. 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. $ SETTING UP A WEB SERVER 59 By Simon Collin. Published 1997. $ O R D E R H E R E P&P 69 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  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  DIGITAL ELECTRONICS ..................................................$65.00  ESSENTIAL LINUX..........................................................$85.00               ORDER TOTAL: $...................... Orders over $100 P&P free in Australia. AUST: Add $A5.50 per book NZ: Add $A10 per book, $A15 elsewhere 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. 65 $ SEE ELSEWHERE IN THIS ISSUE FOR: SILCON CHIP’s COMPUTER OMNIBUS SILCON CHIP’s ELECTRONICS TEST BENCH ZOOM EFI TECH SPECIAL SILCON CHIP BINDERS SILCON CHIP GIANT WALLCHART TAX INVOICE 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.............................. 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 FEBRUARY 2001  87 ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST FEBRUARY 2001  87 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. Philips humidity sensor for weather station I am trying to build the “Three Function Weather Station “featured in the April 1993 edition of SILICON CHIP. My problem is that I cannot source the Philips 232269190001 humidity sensor. Would you know where I can obtain one? (J. E., via email) • The Philips sensor is not readily obtainable now but a similar unit can be obtained from Farnell Components. Its order code is 414-669 but unfortunately its cost is $41.33 plus tax. Phone 1300 361 005. Bridge amplifier for LM3786s I am referring to the bridge amplifier published in “Cir­cuit Notebook” in the June 1996 issue of SILICON CHIP. Does it actually work OK? I see that you have used two LM3886 chips but I have two LM3876 instead. Will these work as direct replacements and what do you think the power output would be? (J. L., via email). • Of course it works. Would we have published otherwise? Yes, you can use LM3876s without changes but you will get more power from LM3886s because they are more suited to 4Ω loads. This is im­portant because if you are using an 8Ω speaker, each amplifier in the bridge will “see” 4Ω. Speed control for electric outboard I would like your advice on whether the motor speed control published in the June 1997 issue is suitable for my application. I wish to control the speed of my 12V electric outboard motor. I have tested its power consumption when in water, the amperage being around 19.7A. I understand that the motor will draw more current than this when under a heavier load (eg, when going though weeds). Because of this, it has been suggested to me that the modi­fications for high current use, as outlined in the article, may not be sufficient. Ideally, I would like to run a more powerful motor from this circuitry so I would like it to handle up to 50A. I will be happy to have it run my existing motor, however. If this circuit cannot be modified sufficiently, can you suggest an alternative? (D. D., via email). • The circuit as it stands will not work. You would need to use at least four Mosfets, each with their own 4.7Ω gate resis­tors and you would Electric fence controller for plasma display I am about to build the Electric Fence Controller from the July 1995 edition of SILICON CHIP, mainly because I have all the parts at hand. I wish to use it as a small plasma display using a light globe. Is the 5kV output high enough to get a good display or is it possible to increase the output? (J. B., via email). • 5kV is not enough for a plasma display; you need around 10kV to 20kV and the frequency of the sparks would have to be greatly increased to around 100Hz. To do this, you would have to modify the electric fence 88  Silicon Chip circuit so that it was the same as the Jacob’s Ladder circuit published in September 1995. The modified circuit pulls a lot more current and produces very hot sparks. Even so, it may not be enough for a really good plasma display. You might want to have a look at the plasma display article published in the September 1998 issue. We also published articles on plasma displays in August & November 1988. We can supply back issues or photostat copies of these articles for $7.70 each, including postage. still need heatsinking and you would need to “beef up” the copper tracks to the Mosfets to make sure they can handle the current. A better choice might be to use the 50A speed controller featured in the May 2000 issue but you will need a separate 5V rail to run the ZN409 and the accompanying pulse generator cir­cuit. We can supply the May 2000 issue for $7.70 including post­age. Help wanted with DVD audio levels I find the sound on DVDs is so dynamic that I frequently have to adjust the volume throughout the movie because of wide audio variations. I built a SILICON CHIP Surround Sound Dolby Decoder kit which works fine and I would like to know if there is a kit available to tame the audio dynamics down without affecting the surround sound decoding. I am using a PC-based DVD and feeding the sound card output to the Dolby Surround Decoder. (C. B., via email). • Have a look at the CD Compressor we described in the June 2000 issue. It is designed for exactly this application. Low-fuel indicator flashing, not steady I recently purchased and built a Low Fuel Indicator, as described in the February 1993 issue of SILICON CHIP. While the kit works, it has some “features” that do not seem to be in accordance with the circuit description. I have fitted the unit to a Datsun 1200 which has a bi-metal strip fuel gauge and a resistance wire sender unit. The gauge shows full when the sender unit wire is grounded. When the ignition is first turned on and the fuel tank is less than half full, the indicator light flashes a few times and then extinguishes. I have adjusted the unit so that the indicator lights when the gauge is about three quarters empty, with the car stationary. When the tank gets to about 7/8ths empty and the car is being driven, the unit starts to flash on and off, slowly at first (perhaps once a kilometre) and the flashing rate increases to about once per second as the tank approaches empty. It does not seem to ever come on permanently, despite almost running out of fuel and having less than two litres left. I would appreciate any suggestions for a cure, although the unit is still useful and serves its purpose (stopping my son from running out of fuel, which he has done four times in one month). (G. P., via email). • It sounds as though the 220µF capacitor is open circuit or is the wrong value. Try changing it. Speed control for a centrifuge Can you please help with the following? I have been asked to repair an old centrifuge. The unit would not regulate the speed of the drive motor. The electronic control is unservice­ able. It is a small pack similar to a light dimmer but rated at 700VA (watts). Standard light dimmers are normally 300VA. So I built the universal motor speed controller kit from the September 1992 issue. The problem is that the controller will not reduce the speed to a low level. I would have thought that it would regulate from 0 RPM to full speed. The centrifuge needs to run from 0 to about 3500 RPM. The motor does not start until the control knob is about 1/3 advanced and jumps to about 1/4 full speed with the preset at zero ohms. Adjusting the preset starts the motor spin­ning at a lower setting of the main control but the speed is about the same. I have added the 1kΩ resistor in place of the link and tried increasing the value of this resistor. I also tried in­creasing and decreasing the value of the 150kΩ resistor, all with no luck! I have checked all components and they seem OK. The original control says “700VA Triac control, 240V only” so a Triac control must be able to do the job. Can you suggest a cure or better mod? (R. M., via email). • The September 1992 design will not regulate from zero to full speed. Essentially, it applies about 170VAC 3-55L loudspeakers blown up Some years ago I built the Studio 3-55L 3-Way Loudspeaker System described in the September 1991 issue. I used to enjoy listening to them but have managed to blow them up a few times. How? I was using these speakers with an amplifier and preamplifier described in another magazine. In the beginning, too much volume blew up the Magnavox 12WRs then I bought a new Samsung fridge that creates a pop when the compressor switches off. These pops helped to destroy the second set of 12WRs, so I replaced them with some better quality higher-rated speakers from Jaycar (Polycone CW-2130). I also installed some varistors on the 240VAC input side of the amp­lifi­er and some polyswitches on the output side of the amplifier. But the pops didn’t stop. Later, high volume has blown up the new woofers and partly cooked the crossover networks. I would like to know how to filter out the pops without having to rewire this house – I’m still only renting in the bush and I had to move the household pressure pump to another circuit for the same reason (induced pops when switching on and off). I would also like to know how you think the 12-inch Re­ sponse 200W Polycone (CW-2138) or (maximum) to the motor so at best it will run at about 75% maximum speed at no load. At the low end it may run at about 20% of maximum speed but not smoothly; ie, it will “cog”. For a wider range of speed control, you need our full wave design published in November 1997. This is rated at up to 10A. We are assuming, of course, that the motor is a universal type (ie, series wound with brushes). On the other hand, if it is a small “shaded pole” motor it might work with a modified light dimmer circuit with a Triac rated at 6A or more. It will need a snubber circuit across the Triac to ensure that it will “commutate” properly with an induc­tive Carbon Fibre (CW-2145) Woofers from Jaycar would go with a set of heavy-duty crossover networks in these boxes? I have read every issue of your great magazine since you started in 1987 and find it very informative and useful. You have designed some great projects over the years. (C. L., via email). • First, the fridge should not cause loud pops in the amplifi­er. It suggests that the amplifier or pre­amp­lifier is very prone to EMI (electromagnetic interference). Possibly the amplifier is unstable. Try using a power filter on the input to the amplifier and make sure that the speaker and input leads are well away from the fridge. Second, run the fridge on a different power circuit if you can. Really, the popping problem lies with the preamp/amplifier and not the speakers. Of course, if you regularly overdrive the amplifier it will tend to blow the speakers regardless of their power ratings. Yes, you can use the suggested woofers in your sealed boxes but we really can’t say which ones would be better or even if they would give close to optimum performance. To get the best performance it is necessary to do a full redesign using the Thiele-Small parameters, etc. It should not be necessary to change the crossovers. If you have blown them, it suggests that you are driving the speakers to really excessive levels. load. A circuit along these lines was published as the Speedi-Watt controller in the December 1987 issue of SILICON CHIP. While the kit is no longer available you could modify a commercial light dimmer along the same lines. Fluorescent starter makes buzzing noise I built the Fluorescent Starter from the August 1996 issue. It works fine and is able to start a fluorescent light almost instantaneously. The problem is that it buzzes after it starts the fluorescent light. There is no RFI emitted, just the buzzing which makes it irritating. Is there a way to eliminate October 2000  89 Compact fluoro inverter for horse float I would like to modify the Compact Fluorescent Lamp Driver kit (SILICON CHIP, July 2000) to operate off a 24VDC supply. We have a horse truck that has on-board 24VDC only, with ample cur­ rent. We use this truck to transport horses to venues. We also sleep in the truck. Some venues we attend don’t have 240V avail­able and we are forced to use torches and Tilly lamps at night. My electrician friend and I have thought about wiring up the truck using CFLs as a primary lighting source in the horse area and sleep- the buzz? Could I connect a capacitor or retrim the circuit RC network to reduce or increase the timing and thereby eliminate the buzz sound? (M. O., via email). • A buzzing sound can be produced by the Mosfet and is due to its rapid switching. The same effect can be heard with SCRs, Triacs and the power transistors in high power audio amplifiers when handling the higher frequencies. Having said that, it should only buzz while starting and then any buzzing would be louder from the ballast as the starter is then out of circuit. If you are concerned with the buzzing during starting then the only way to stop it would be to fully encapsulate the unit in epoxy resin. CD input for 50W module Will your 50W amplifier module (March 1994) accept a CD input without pre-amplification and still ing quarters. These are thoughts on modifying the above kit. All the ICs would have to run from a 12V regulator and the centre tap of the primary of T1 would be taken to +24V via L1. The voltage rating of the 2 x 4700µF electros would be upgraded to say 35V. I also wonder if the primary windings of T1 have to be increased by a few turns? (B. B., Mittagong, NSW). • As you state, it will be necessary to run the ICs from a 12V regulator. The inverter transformer will need to be rewound with more turns on the primary; ie, 2 x 12 turns instead of 2 x 6. The 16V zeners should also be increased to 39V. produce full power? If not, can I increase the gain so that it will? If so, how? (C. C., via email). • Input sensitivity for full power is 1V so a CD player could overdrive with its 2V (max.) signal. Fit a 50kΩ log pot and 22µF bipolar capacitor from the wiper to the amplifier input to solve the problem. Cheap headlight dimmer wanted I am looking for a way to dim my headlights to act as park­ing lamps. Just wondering if there is a cheaper way than the $50 Jaycar kit for the Daytime Running Lights project featured in the August 1999 issue, to run them at about 50% brightness? (A. L., via email). • Have a look at the 10A Speed Controller kit we published in June 1997. It is available from Jaycar (Cat. KC-5225) for $21.05. You will need the dimmer modification featured in the October 1997 issue. Jumbo LED clock has faulty displays I am having problems with the Jumbo LED Clock in the March 1997 issue. I purchased the displays and most of the ICs from Jaycar. The hour display blinks at one-second intervals, the third display does not light at all and some segments in the fourth display do not light up. I have replaced most of the ICs. (D. B., Port Macquarie, NSW). • The fact that the hour display blinks at one second inter­vals suggests that there is a short on the display board (or between the inter-board connections) associated with the flashing colon; ie, the DP connections to DISP2 & DISP3. The display that does not light is likely to have an open circuit in the connections to the common cathode line, pins 3 & 8. The missing segments for the fourth display will be associated with open circuit connections to the relevant 390Ω resistors, the display pins or the interboard connections. We do not think it should be necessary to replace any ICs as most of the problems are likely to be due to missed or bridged solder connections. You may need a magnifying glass to carefully inspect the PCboard for these faults. Notes & Errata Structured Cabling Systems (August 2000): in the Cat5 cable diagram on page 74, pair 1 (blue/blue-white) are shown reversed - blue should connect to pin 4 and blue-white to pin 5 of the RJ45 jack. Fortunately, this diagram would rarely be translated into practice because the vast majority of RJ45 jacks are colour-coded to show which SC wires go to which pins. 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. 90  Silicon Chip DON’T UTER COMP MISS OMNIBUS THE ’BUS! www.siliconchip.com.au SILICON CHIP’S 132 Pages $ 95 * 9 ISBN 0 95852291 X 9780958522910 09 9 780958 522910 IN LINCLUDES FEA U TUR X E A collection of computer features from the pages of SILICON CHIP magazine Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NT o RT Do you feel a little “left behind” by the latest advances and developments in computer hardware and software? Don’t miss the bus: get the ’bus! THIS IS IT: The computer reference you’ve been asking for! SILICON CHIP's Computer Omnibus is a valuable compendium of the most-requested computer hardware and software features from recent issues of SILICON CHIP magazine - all in one handy volume. Here's just a sample of the contents: Troubleshooting your PC: what to do when things go wrong NO Choosing, installing and taming computer networks AVA W Upgrading and overclocking CPUs DIRE ILABLE C Hard disk drive upgrades, tune-ups and tips SILIC T FROM Windows 3.1, 95, 98 and NT tips and tricks ON just $ CHIP The Y2K Bug - and how to swat it 125O* INC All about Linux GST & P& P And much more!!! ORDER NOW: Use the handy order form in this issue or call (02) 9979 5644, 9-5 Mon-Fri with your credit card details. * Price includes GST 09 Silicon Chip Back Issues April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2; Amtrak Passenger Services. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; The Burlington Northern Railroad. April 1993: Solar-Powered Electric Fence; Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Converter; Digital Clock With Battery Back-Up. June 1993: AM Radio Trainer, Pt.1; Remote Control For The Woofer Stopper; Digital Voltmeter For Cars; Build A Windows-Based Logic Analyser. July 1993: Single Chip Message Recorder; Light Beam Relay Extender; AM Radio Trainer, Pt.2; Quiz Game Adjudicator; Windows-Based Logic Analyser, Pt.2; Antenna Tuners – Why They Are Useful. March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; A Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateur Radio & TV. July 1989: Exhaust Gas Monitor; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; The NSW 86 Class Electrics. April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; High Or Low Fluid Level Detector; Studio Series 20-Band Stereo Equaliser, Pt.2. May 1991: 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1. October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 2-Chip Portable AM Stereo Radio, Pt.2; A Look At Australian Monorails. July 1991: Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Railways. September 1991: Digital Altimeter For Gliders & Ultralights; Ultrasonic Switch For Mains Appliances; The Basics Of A/D & D/A Conversion; Plotting The Course Of Thunderstorms. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Phone Patch For Radio Amateurs; Active Antenna Kit; Designing UHF Transmitter Stages. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator For Model Railways Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders, Pt.2; Military Applications Of R/C Aircraft. February 1990: A 16-Channel Mixing Desk; Build A High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2. November 1991: Build A Colour TV Pattern Generator, Pt.1; A Junkbox 2-Valve Receiver; Flashing Alarm Light For Cars; Digital Altimeter For Gliders, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; Build a Turnstile Antenna For Weather Satellite Reception. March 1990: Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC; The Australian VFT Project. April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch (VOX) With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter; Servicing Your Microwave Oven. June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load Protector For Power Supplies; Car Speed Alarm. July 1990: Digital Sine/Square Generator, Pt.1 (covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Build A Simple Electronic Die; A Low-Cost Dual Power Supply; Inside A Coal Burning Power Station. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Generator, Pt.2. September 1990: A Low-Cost 3-Digit Counter Module; Build A Simple Shortwave Converter For The 2-Metre Band; The Bose Lifestyle Music System (Review); The Care & Feeding Of Nicad Battery Packs (Getting The Most From Nicad Batteries). October 1990: The Dangers of PCBs; Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; NE602 Converter Circuits. November 1990: Connecting Two TV Sets To One VCR; Build An Egg Timer; Low-Cost Model Train Controller; 1.5V To 9V DC Converter; Introduction To Digital Electronics; 6-Metre Amateur Transmitter. December 1990: 100W DC-DC Converter For Car Amplifiers; Wiper Pulser For Rear Windows; 4-Digit Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; Index To Volume 3. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine; Two-Tone Alarm Module; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers of Servicing Microwave Ovens. ORDER FORM Please send thethe following back issues: Please send following back issues:    December 1991: TV Transmitter For VCRs With UHF Modulators; Infrared Light Beam Relay; Colour TV Pattern Generator, Pt.2; Index To Volume 4. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Experiments For Your Games Card. March 1992: TV Transmitter For VHF VCRs; Thermostatic Switch For Car Radiator Fans; Coping With Damaged Computer Directories; Guide Valve Substitution In Vintage Radios. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Understanding Computer Memory; Aligning Vintage Radio Receivers, Pt.1. June 1992: Multi-Station Headset Intercom, Pt.1; Video Switcher For Camcorders & VCRs; IR Remote Control For Model Railroads, Pt.3; 15-Watt 12-240V Inverter; A Look At Hard Disc Drives. August 1992: Automatic SLA Battery Charger; Miniature 1.5V To 9V DC Converter; 1kW Dummy Load Box For Audio Amplifiers; Troubleshooting Vintage Radio Receivers; The MIDI Interface Explained. October 1992: 2kW 24VDC - 240VAC Sinewave Inverter; Multi-Sector Home Burglar Alarm, Pt.2; Mini Amplifier For Personal Stereos; A Regulated Lead-Acid Battery Charger. January 1993: Flea-Power AM Radio Transmitter; High Intensity LED Flasher For Bicycles; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.4; Speed Controller For Electric Models, Pt.3. February 1993: Three Projects For Model Railroads; Low Fuel Indicator For Cars; Audio Level/VU Meter (LED Readout); An Electronic Cockroach; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.5. March 1993: Solar Charger For 12V Batteries; Alarm-Triggered Security Camera; Reaction Trainer; Audio Mixer for Camcorders; A 24-Hour Sidereal Clock For Astronomers. August 1993: Low-Cost Colour Video Fader; 60-LED Brake Light Array; Microprocessor-Based Sidereal Clock; Southern Cross Z80-Based Computer; A Look At Satellites & Their Orbits. September 1993: Automatic Nicad Battery Charger/Discharger; Stereo Preamplifier With IR Remote Control, Pt.1; In-Circuit Transistor Tester; +5V to ±15V DC Converter; Remote-Controlled Cockroach. October 1993: Courtesy Light Switch-Off Timer For Cars; Wireless Microphone For Musicians; Stereo Preamplifier With IR Remote Control, Pt.2; Electronic Engine Management, Pt.1. November 1993: High Efficiency Inverter For Fluorescent Tubes; Stereo Preamplifier With IR Remote Control, Pt.3; Siren Sound Generator; Engine Management, Pt.2; Experiments For Games Cards. December 1993: Remote Controller For Garage Doors; Build A LED Stroboscope; Build A 25W Audio Amplifier Module; A 1-Chip Melody Generator; Engine Management, Pt.3; Index To Volume 6. January 1994: 3A 40V Adjustable Power Supply; Switching Regulator For Solar Panels; Printer Status Indicator; Mini Drill Speed Controller; Stepper Motor Controller; Active Filter Design; Engine Management, Pt.4. February 1994: Build A 90-Second Message Recorder; 12-240VAC 200W Inverter; 0.5W Audio Amplifier; 3A 40V Adjustable Power Supply; Engine Management, Pt.5; Airbags In Cars – How They Work. March 1994: Intelligent IR Remote Controller; 50W (LM3876) Audio Amplifier Module; Level Crossing Detector For Model Railways; Voice Activated Switch For FM Microphones; Engine Management, Pt.6. April 1994: Sound & Lights For Model Railway Level Crossings; Discrete Dual Supply Voltage Regulator; Universal Stereo Preamplifier; Digital Water Tank Gauge; Engine Management, Pt.7. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Multi-Channel Infrared Remote Control; Dual Electronic Dice; Simple Servo Driver Circuits; Engine Management, Pt.8. June 1994: 200W/350W Mosfet Amplifier Module; A Coolant Level Alarm For Your Car; 80-Metre AM/CW Transmitter For Amateurs; Converting Phono Inputs To Line Inputs; PC-Based Nicad Battery Monitor; Engine Management, Pt.9. July 1994: Build A 4-Bay Bow-Tie UHF Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; Po August 1994: High-Power Dimmer For Incandescent Lights; Microprocessor-Controlled Morse Keyer; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper; Engine Management, Pt.11. September 1994: Automatic Discharger For Nicad Battery Packs; MiniVox Voice Operated Relay; Image Intensified Night Viewer; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Microphones, Pt.2; Engine Management, Pt.12. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Build A Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Build A Temperature Controlled Soldering Station; Electronic Engine Management, Pt.13. November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-Metre DSB Amateur Transmitter; Twin-Cell Nicad Discharger (See May 1993); How To Plot Patterns Direct to PC Boards. December 1994: Dolby Pro-Logic Surround Sound Decoder, Pt.1; Easy-To-Build Car Burglar Alarm; Three-Spot Low Distortion Sinewave Oscillator; Clifford – A Pesky Electronic Cricket; Remote Control System for Models, Pt.1; Index to Vol.7. ____________________________________________________________ 10% OF F SUBSCR TO IB OR IF Y ERS OU 10 OR M BUY ORE Enclosed is my cheque/money order for $­______or please debit my: ❏ Bankcard ❏ Visa Card ❏ Master Card Card No. Signature ___________________________ Card expiry date_____ /______ Name ______________________________ Phone No (___) ____________ PLEASE PRINT Street ______________________________________________________ Suburb/town _______________________________ Postcode ___________ 92  Silicon Chip Note: prices include postage & packing Australia ....................... $A7.70 (incl. GST) Overseas (airmail) ............................ $A10 Detach and mail to: Silicon Chip Publications, PO Box 139, Collaroy, NSW, Australia 2097. Or call (02) 9979 5644 & quote your credit card details or fax the details to (02) 9979 6503. Email: silchip<at>siliconchip.com.au January 1995: Sun Tracker For Solar Panels; Battery Saver For Torches; Dolby Pro-Logic Surround Sound Decoder, Pt.2; Dual Channel UHF Remote Control; Stereo Microphone Pre­amp­lifier. February 1997: Cathode Ray Oscilloscopes, Pt.6; PC-Controlled Moving Message Display; Computer Controlled Dual Power Supply, Pt.2; AlertA-Phone Loud Alarm; Control Panel For Multiple Smoke Alarms, Pt.2. February 1995: 50-Watt/Channel Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel Thermometer With LCD Readout; Wide Range Electrostatic Loudspeakers, Pt.1; Oil Change Timer For Cars; Remote Control System For Models, Pt.2. March 1997: Driving A Computer By Remote Control; Plastic Power PA Amplifier (175W); Signalling & Lighting For Model Railways; Build A Jumbo LED Clock; Cathode Ray Oscilloscopes, Pt.7. March 1995: 50 Watt Per Channel Stereo Amplifier, Pt.1; Subcarrier Decoder For FM Receivers; Wide Range Electrostatic Loudspeakers, Pt.2; IR Illuminator For CCD Cameras; Remote Control System For Models, Pt.3; Simple CW Filter. April 1995: FM Radio Trainer, Pt.1; Photographic Timer For Dark­ rooms; Balanced Microphone Preamp. & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. May 1995: Build A Guitar Headphone Amplifier; FM Radio Trainer, Pt.2; Transistor/Mosfet Tester For DMMs; A 16-Channel Decoder For Radio Remote Control; Introduction to Satellite TV. April 1997: Simple Timer With No ICs; Digital Voltmeter For Cars; Loudspeaker Protector For Stereo Amplifiers; Model Train Controller; A Look At Signal Tracing; Pt.1; Cathode Ray Oscilloscopes, Pt.8. May 1997: Teletext Decoder For PCs; Build An NTSC-PAL Converter; Neon Tube Modulator For Light Systems; Traffic Lights For A Model Intersection; The Spacewriter – It Writes Messages In Thin Air; A Look At Signal Tracing; Pt.2; Cathode Ray Oscilloscopes, Pt.9. June 1997: PC-Controlled Thermometer/Thermostat; Colour TV Pattern Generator, Pt.1; Build An Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For A Stepper Motor; Cathode Ray Oscilloscopes, Pt.10. June 1995: Build A Satellite TV Receiver; Train Detector For Model Railways; 1W Audio Amplifier Trainer; Low-Cost Video Security System; Multi-Channel Radio Control Transmitter For Models, Pt.1. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Simple Square/Triangle Waveform Generator; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers. July 1995: Electric Fence Controller; How To Run Two Trains On A Single Track (Incl. Lights & Sound); Setting Up A Satellite TV Ground Station; Build A Reliable Door Minder. August 1997: The Bass Barrel Subwoofer; 500 Watt Audio Power Amplifier Module; A TENs Unit For Pain Relief; Addressable PC Card For Stepper Motor Control; Remote Controlled Gates For Your Home. August 1995: Fuel Injector Monitor For Cars; Gain Controlled Microphone Preamp; Audio Lab PC-Controlled Test Instrument, Pt.1; How To Identify IDE Hard Disk Drive Parameters. September 1997: Multi-Spark Capacitor Discharge Ignition; 500W Audio Power Amplifier, Pt.2; A Video Security System For Your Home; PC Card For Controlling Two Stepper Motors; HiFi On A Budget; Win95, MSDOS.SYS & The Registry. September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; The Vader Voice; Jacob’s Ladder Display; Audio Lab PC-Controlled Test Instrument, Pt.2. October 1995: Geiger Counter; 3-Way Bass Reflex Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Fast Charger For Nicad Batteries; Digital Speedometer & Fuel Gauge For Cars, Pt.1. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­ verter For The 80M Amateur Band, Pt.1; PIR Movement Detector; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.1; Digital Speedometer & Fuel Gauge For Cars, Pt.2. December 1995: Engine Immobiliser; 5-Band Equaliser; CB Transverter For The 80M Amateur Band, Pt.2; Subwoofer Controller; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.2; Knock Sensing In Cars; Index To Volume 8. January 1996: Surround Sound Mixer & Decoder, Pt.1; Magnetic Card Reader; Build An Automatic Sprinkler Controller; IR Remote Control For The Railpower Mk.2; Recharging Nicad Batteries For Long Life. February 1996: Three Remote Controls To Build; Woofer Stopper Mk.2; 10-Minute Kill Switch For Smoke Detectors; Basic Logic Trainer; Surround Sound Mixer & Decoder, Pt.2. March 1996: Programmable Electronic Ignition System; Zener Diode Tester For DMMs; Automatic Level Control For PA Systems; 20ms Delay For Surround Sound Decoders; Multi-Channel Radio Control Transmitter; Pt.2; Cathode Ray Oscilloscopes, Pt.1. April 1996: Cheap Battery Refills For Mobile Telephones; 125W Audio Power Amplifier Module; Knock Indicator For Leaded Petrol Engines; Multi-Channel Radio Control Transmitter; Pt.3; Cathode Ray Oscilloscopes, Pt.2. May 1996: Upgrading The CPU In Your PC; High Voltage Insulation Tester; Knightrider Bi-Directional LED Chaser; Simple Duplex Intercom Using Fibre Optic Cable; Cathode Ray Oscilloscopes, Pt.3. June 1996: BassBox CAD Loudspeaker Software Reviewed; Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. July 1996: Installing a Dual Boot Windows System On Your PC; Build A VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser; Single Channel 8-bit Data Logger. August 1996: Electronics on the Internet; Customising the Windows Desktop; Introduction to IGBTs; Electronic Starter For Fluores­cent Lamps; VGA Oscilloscope, Pt.2; 350W Amplifier Module; Masthead Amplifier For TV & FM; Cathode Ray Oscilloscopes, Pt.4. September 1996: VGA Oscilloscope, Pt.3; IR Stereo Headphone Link, Pt.1; High Quality PA Loudspeaker; 3-Band HF Amateur Radio Receiver; Cathode Ray Oscilloscopes, Pt.5. October 1996: Send Video Signals Over Twisted Pair Cable; Power Control With A Light Dimmer; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Build A Multi-Media Sound System, Pt.1; Multi-Channel Radio Control Transmitter, Pt.8. November 1996: Adding A Parallel Port To Your Computer; 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; How To Repair Domestic Light Dimmers; Build A Multi-Media Sound System, Pt.2; 600W DC-DC Converter For Car Hifi Systems, Pt.2. December 1996: Active Filter Cleans Up CW Reception; Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Volume 9. January 1997: How To Network Your PC; Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source (For Sound Level Meter Calibration); Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Monitors Eight Temperatures. March 1999: Getting Started With Linux; Pt.1; Build A Digital Anemometer; 3-Channel Current Monitor With Data Logging; Simple DIY PIC Programmer; Easy-To-Build Audio Compressor; Low Distortion Audio Signal Generator, Pt.2; Electric Lighting, Pt.12. April 1999: Getting Started With Linux; Pt.2; High-Power Electric Fence Controller; Bass Cube Subwoofer; Programmable Thermostat/ Thermometer; Build An Infrared Sentry; Rev Limiter For Cars; Electric Lighting, Pt.13; Autopilots For Radio-Controlled Model Aircraft. May 1999: The Line Dancer Robot; An X-Y Table With Stepper Motor Control, Pt.1; Three Electric Fence Testers; Heart Of LEDs; Build A Carbon Monoxide Alarm; Getting Started With Linux; Pt.3. June 1999: FM Radio Tuner Card For PCs; X-Y Table With Stepper Motor Control, Pt.2; Programmable Ignition Timing Module For Cars, Pt.1; Hard Disk Drive Upgrades Without Reinstalling Software; What Is A Groundplane Antenna?; Getting Started With Linux; Pt.4. July 1999: Build The Dog Silencer; A 10µH to 19.99mH Inductance Meter; Build An Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3; The Hexapod Robot. August 1999: Remote Modem Controller; Daytime Running Lights For Cars; Build A PC Monitor Checker; Switching Temperature Controller; XYZ Table With Stepper Motor Control, Pt.4; Electric Lighting, Pt.14; DOS & Windows Utilities For Reversing Protel PC Board Files. September 1999: Automatic Addressing On TCP/IP Networks; Wireless Networking Without The Hassles; Autonomouse The Robot, Pt.1; Voice Direct Speech Recognition Module; Digital Electrolytic Capacitance Meter; XYZ Table With Stepper Motor Control, Pt.5; Peltier-Powered Can Cooler. October 1997: Build A 5-Digit Tachometer; Add Central Locking To Your Car; PC-Controlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3; Customising The Windows 95 Start Menu. October 1999: Sharing A Modem For Internet & Email Access (WinGate); Build The Railpower Model Train Controller, Pt.1; Semiconductor Curve Tracer; Autonomouse The Robot, Pt.2; XYZ Table With Stepper Motor Control, Pt.6; Introducing Home Theatre. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Relocating Your CD-ROM Drive; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. November 1999: USB – Hassle-Free Connections TO Your PC; Electric Lighting, Pt.15; Setting Up An Email Server; Speed Alarm For Cars, Pt.1; Multi-Colour LED Christmas Tree; Build An Intercom Station Expander; Foldback Loudspeaker System For Musicians; Railpower Model Train Controller, Pt.2. December 1997: Build A Speed Alarm For Your Car; Two-Axis Robot With Gripper; Loudness Control For Car Hifi Systems; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Volume 10. January 1998: Build Your Own 4-Channel Lightshow, Pt.1 (runs off 12VDC or 12VAC); Command Control System For Model Railways, Pt.1; Pan Controller For CCD Cameras; Build A One Or Two-Lamp Flasher; Understanding Electric Lighting, Pt.3. February 1998: Hot Web Sites For Surplus Bits; Multi-Purpose Fast Battery Charger, Pt.1; Telephone Exchange Simulator For Testing; Command Control System For Model Railways, Pt.2; Build Your Own 4-Channel Lightshow, Pt.2; Understanding Electric Lighting, Pt.4. April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Build A Laser Light Show; Understanding Electric Lighting; Pt.6; Jet Engines In Model Aircraft. May 1998: Troubleshooting Your PC, Pt.1; Build A 3-LED Logic Probe; Automatic Garage Door Opener, Pt.2; Command Control For Model Railways, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. June 1998: Troubleshooting Your PC, Pt.2; Understanding Electric Lighting, Pt.7; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. December 1999: Internet Connection Sharing Using Hardware; Electric Lighting, Pt.16; Index To Volume 12; Build A Solar Panel Regulator; The PC Powerhouse (gives fixed +12V, +9V, +6V & +5V rails); The Fortune Finder Metal Locator; Speed Alarm For Cars, Pt.2; Railpower Model Train Controller, Pt.3. January 2000: Spring Reverberation Module; An Audio-Video Test Generator; Build The Picman Programmable Robot; A Parallel Port Interface Card; Off-Hook Indicator For Telephone Lines; B&W Nautilus 801 Monitor Loudspeakers (Review). February 2000: Build A Multi-Sector Sprinkler Controller; A Digital Voltmeter For Your Car; An Ultrasonic Parking Radar; Build A Safety Switch Checker; A Sine/Square Wave Oscillator For Your Workbench; Marantz SR-18 Home Theatre Receiver (Review); The “Hot Chip” Starter Kit (Review). March 2000: Doing A Lazarus On An Old Computer; Ultra Low Distortion 100W Amplifier Module, Pt.1; Electronic Wind Vane With 16-LED Display; Glowplug Driver For Powered Models; The OzTrip Car Computer, Pt.1; Multisim Circuit Design & Simulation Package (Review). April 2000: A Digital Tachometer For Your Car; RoomGuard – A LowCost Intruder Alarm; Build A Hot wire Cutter; The OzTrip Car Computer, Pt.2; Build A Temperature Logger; Atmel’s ICE 200 In-Circuit Emulator; How To Run A 3-Phase Induction Motor From 240VAC. July 1998: Troubleshooting Your PC, Pt.3 (Installing A Modem And Sorting Out Problems); Build A Heat Controller; 15-Watt Class-A Audio Amplifier Module; Simple Charger For 6V & 12V SLA Batteries; Automatic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. May 2000: Building the Ultra-LD Stereo Amplifier, Pt.2; Build A LED Dice (With PIC Microcontroller); A Low-Cost AT Keyboard Translator (Converts IBM Scan-Codes To ASCII); 50A Motor Speed Controller For Models; Dolby Headphone – Five Channels Of Surround Sound; What’s Inside A Furby. August 1998: Troubleshooting Your PC, Pt.4 (Adding Extra Memory); Build The Opus One Loudspeaker System; Simple I/O Card With Automatic Data Logging; Build A Beat Triggered Strobe; A 15-Watt Per Channel Class-A Stereo Amplifier. June 2000: Automatic Rain Gauge With Digital Readout; Parallel Port VHF FM Receiver; Li’l Powerhouse Switchmode Power Supply (1.23V to 40V) Pt.1; CD Compressor For Cars Or The Home; Sony’s New Digital Handycam (Review). September 1998: Troubleshooting Your PC, Pt.5 (Software Problems & DOS Games); A Blocked Air-Filter Alarm; A Waa-Waa Pedal For Your Guitar; Build A Plasma Display Or Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. July 2000: A Moving Message Display; Compact Fluorescent Lamp Driver; El-Cheapo Musicians’ Lead Tester; Li’l Powerhouse Switchmode Power Supply (1.23V to 40V) Pt.2; Say Bye-Bye To Your 12V Car Battery. October 1998: CPU Upgrades & Overclocking; Lab Quality AC Millivoltmeter, Pt.1; PC-Controlled Stress-O-Meter; Electronic Guitar Limiter; 12V Trickle Charger For Float Conditions; Add An External Battery To Your Flashgun. August 2000: Build A Theremin For Really Eeerie Sounds; Come In Spinner (writes messages in “thin-air”); Loudspeaker Protector & Fan Controller For The Ultra-LD Stereo Amplifier; Proximity Switch For 240VAC Lamps; Structured Cabling For Computer Networks. November 1998: The Christmas Star; A Turbo Timer For Cars; Build A Poker Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Setting Up A LAN Using TCP/IP; Understanding Electric Lighting, Pt.9; Improving AM Radio Reception, Pt.1. December 1998: Protect Your Car With The Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; A Regulated 12V DC Plugpack; Build Your Own Poker Machine, Pt.2; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Glider Operations. January 1999: The Y2K Bug & A Few Other Worries; High-Voltage Megohm Tester; Getting Going With BASIC Stamp; LED Bargraph Ammeter For Cars; Keypad Engine Immobiliser; Improving AM Radio Reception, Pt.3; Electric Lighting, Pt.10 February 1999: Installing A Computer Network (Network Types, Hubs, Switches & Routers); Making Panels For Your Projects; Low Distortion Audio Signal Generator, Pt.1; Command Control Decoder For Model Railways; Digital Capacitance Meter; Remote Control Tester; Electric Lighting, Pt.11. September 2000: Build A Swimming Pool Alarm; An 8-Channel PC Relay Board; Fuel Mixture Display For Cars, Pt.1; Protoboards – The Easy Way Into Electronics; Cybug The Solar Fly; Network Troubleshooting With Fluke’s NetTool. PLEASE NOTE: November 1987 to March 1989, June 1989, August 1989, December 1989, May 1990, February 1991, June 1991, August 1991, February 1992, July 1992, September 1992, November 1992, December 1992, May 1993, February 1996 and March 1998 are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or tear sheets) at $7.70 per article (includes p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. A complete index to all articles published to date is available on floppy disk for $11 including p&p, or can be downloaded free from our web site: www.siliconchip.com.au October 2000  93 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 BULLET Colour Cameras 440 Line from $110 Time-Lapse VCRs from $699 ! TWO YEAR WARRANTY ! National Service Centres ! Multinational Manufacturer. COLOUR MONITORS 15 Inch 800 + / 17 Inch 1000 + H-line $499 / $599 THREE YEAR WARRANTY. VIDEO CAMERAS DOME COLOUR from $70 ! Mono from $48 ! BULLET from $85 TWO YEAR WARRANTY * DOME 480 Line 0.05 Lux with SONY CCD & ChipSet from $73 * 380 Line from $69 * 450 Line from $97 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 $179 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 $72 * 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 from $199 * DIY PLUG-IN 20 metre AV Cable Sets from $18 ! UP TO 5 YEARS WARRANTY * OVERNIGHT DELIVERY * www.allthings.com.au 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. www.allthings.com.au 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 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 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. KITS KITS AND MORE KITS! Check ‘em out at www.ozitronics.com HOME CCTV Mono / Colour PAKS Only! $113 / $140 DIY Plug-In to TV / VCR 20 metre Cable, Plug Pack & Camera www.allthings.com.au TELEPHONE EXCHANGE SIMULATOR, SC February 1998. Test equipment without the cost of telephone lines. Melbourne 9806 0110. 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 Time-Lapse VCR only $699 with CCTV Systems 2 Year Warranty ! 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. 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. KIT ASSEMBLY ANY KITS assembled/repaired: professional, speedy service. Phone Nev­ille Walker (07) 3857 2752 or email flashdog<at>optusnet.com.au KITS ASSEMBLED or repaired in Sydney. Phone (02) 9728 6443. 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. WE PAY UP TO $60 for contributions to Circuit Notebook. Send your circuit with a brief description to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. October 2000  95 Silicon Chip Binders Keep your copies safe, secure and always available with SILICON CHIP binders: they’re cheap insurance! Advertising Index Av-Comm Pty Ltd.........................95 REAL VALUE AT $12.95 PLUS P &P  Heavy board covers with 2-tone green vinyl covering Dick Smith Electronics........... 18-21 EMC Technologies.......................77 Emona Instruments...................IBC Evatco.....................................65,83  Each binder holds up to 14 issues so that you can include catalogs Fluke Australia...........................IFC  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Harbuch Electronics....................75 Price: $12.95 (includes GST) plus $5.50 p&p each (available Aust. only). Price includes GST. Investment Technology................43 4D Systems.................................65 Instant PCBs................................95 Jaycar ................................... 45-52 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. 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. Kalex............................................83 Mass Technology.........................77 Microgram Computers..........3,OBC MicroZed Computers...................77 Oatley Electronics........................27 Printed Electronics...................... 95 www.siliconchip.com.au SILICON CHIP’S 132 Pages $ 95 * 9 ISBN 0 95852291 X 9780958522910 09 09 9 780958 522910 Questronix...................................77 Rall Electronics............................77 RF Probes...................................77 COMPUTER OMNIBUS RobotOz......................................77 IN LI CLUDE FEA NU S TUR X E Rola Australia..............................95 R.T.N............................................77 A collection of computer features from the pages of SILICON CHIP magazine SC Computer Omnibus...............91 o Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NT NO W AVA DIRE ILABLE C SILIC T FROM ON just $ CHIP 125 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. RT INC O SC EFI Tech Special....................80 SC Electronics Testbench............59 Silicon Chip Binders....................96 Silicon Chip Bookshop........... 86-87 P&P Note: price includes the GST. Silicon Chip Subscriptions...........58 Silvertone Electronics..................95 Solar Flair/Ecowatch....................95 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. Telephone Technical Services.....35 Vass Electronics..........................77 _____________________________ PC Boards 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. Printed circuit boards for SILICON CHIP projects are made by: Individual membership is $20 pa. Donations are also welcome. Cheques payable to “SOLIS c/- NSAS”, PO Box 214, West Ryde 2114. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730. Email: tpeters<at>pip.elm.mq.edu.au 96  Silicon Chip • RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334.