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siliconchip.com.au July 2009  1 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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.jaycar.com.au Contents Vol.22, No.7; July 2009 www.siliconchip.com.au SILICON CHIP Features 12 The Magic Of Water Desalination The driest continent on Earth is about to get much more drinking water from the sea, thanks to new desalination plants. Here’s a look at how they work – by Geoff Graham The Magic Of Water Desalination – Page 12. 20 Review: Two Low-Cost DVD Recorders Thinking of retiring that ancient VCR and getting a DVD recorder? Here’s a look at two low-cost units: the Tevion DD1018 & the AWA DR711 – by Barrie Smith Lead-Acid Battery Zapper & Desulphator Mk.3 – Page 26. 78 CeBIT: What’s New At Australia’s Largest IT Show? There’s lots to see at CeBIT. We took a stroll around the displays to bring you this report – by Ross Tester Pro jects To Build 26 Lead-Acid Battery Zapper & Desulphator Mk.3 Rejuvenate old lead-acid batteries by zapping them with high-voltage pulses to dissolve the lead-sulphate crystals on their plates. It works with 6V, 12V & 24V batteries & is easy to build – by Jim Rowe 38 Hand-Held Metal Locator Compact unit is ideal for finding steel frames & studs, steel bracing & nails in plaster walls. And it can discriminate between ferrous and non-ferrous metals – by John Clarke 58 Multi-Function Active Filter Module Versatile design is ideal for use as an active crossover in loudspeaker systems but has other uses as well. It can be configured as a low-pass filter, as a highpass filter or as a bandpass filter using on-board jumpers – by John Clarke 80 High-Current, High-Voltage Battery Capacity Meter, Pt.2 Hand-Held Metal Locator – Page 38 This month, we guide you through the once-only setup and calibration procedure. We also tell you how to use it – by Mauro Grassi Special Columns 70 Circuit Notebook (1) RF Preamplifier For World-Band Receivers; (2) Signal Inverter Runs From 5V Rail; (3) Simple Water Spillage Alarm; (4) Accurate Timer Locked To 50Hz Mains Supply; (5) Enhanced Software For The Appliance Energy Meter 44 Serviceman’s Log Car electronics: a whole new ballgame – by the Serviceman 89 Vintage Radio The Lyric 8-Valve Console From The 1920s – by Rodney Champness Departments   2   4 19 37 Publisher’s Letter Mailbag Subscriptions Order Form siliconchip.com.au 57 96 99 102 Product Showcase Ask Silicon Chip Notes & Errata Market Centre Multi-Function Active Filter Module – Page 58. July 2009  1 SILICON SILIC CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc. (Hons.) Technical Editor John Clarke, B.E.(Elec.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc Mauro Grassi, B.Sc. (Hons), Ph.D Photography Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Mike Sheriff, B.Sc, VK2YFK Stan Swan 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 is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $94.50 per year in Australia. For overseas rates, see the order form in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip Publisher’s Letter Natural gas means geosequestration is unnecessary My “Publisher’s Letter” last month poured scorn on “carbon pollution” and geosequestration, which is now known as “Carbon Capture & Storage Technology”. As you might expect, there has been significant criticism of that viewpoint but considerable support as well. Coincidentally, David Knox, CEO of Santos, has put the case for using natural gas to fire Australia’s thermal power stations, some 80% of which are currently coal-fired. As he points out, “if we are serious about confronting climate change, and if we are to deliver the Government’s target of a 60 percent reduction in carbon emission by 2050, we need to reduce the carbon intensity of Australia’s baseload power generation”. He goes on to state “that gas fired power technology (known as combined cycle or CCGT) emits only 40 percent of the carbon emissions of the existing” average coal-fired power station. In fact, it already delivers 80 percent of the carbon reduction hoped for from geosequestration. Now David Knox could be dismissed as simply selling his wares but he is nonetheless correct. He also highlights the peak load ability (as well as base load) of gas-fired stations and their greatly reduced use of water compared to coal-fired stations. In fact, a gas-fired power station only uses 1% of the water required for a coal-fired station. I am not referring to the water required for cooling but to the water required for coal scrubbing. He could have added that the extraction of natural gas causes none of the problems of damage to water resources by coal mining. Nor does it cause subsidence as in the case of long-wall mining or have the need for extremely costly landscape remediation, as in the case of open-cut mining. Nor does a gas-fired station produce huge quantities of ash which must also be disposed of. The more you think about it, using Australia’s massive gas deposits for electricity generation is a very good idea. You can read the full text of the Santos submission to the Australian Government’s energy white paper process on the Santos website at http://www. santos.com/Archive/NewsDetail.aspx?p=121&id=1145 Not only is using natural gas for power stations more environmentally friendly, it is thermodynamically much more efficient, particularly when employed in “combined cycle”. This is where the hot exhaust from the gas turbines is used to generate steam and run a turbo-alternator. The net result is that gas-fired power stations not only emit less carbon dioxide than coalfired stations, they produce far less emissions than would be produced with a coal-fired power station which was using some sort of (yet to be proven) carbon capture and storage system. So rather than introducing an elaborate and expensive emissions trading scheme (ETS), the government should be seriously contemplating converting Australia’s existing coal-fired power stations to gas. And if it cannot do it for the black coal stations, it should certainly do it for the brown coal power stations in Victoria. Admittedly the conversion process will be expensive but it will be much cheaper and easier to implement than the proposed ETS. Furthermore, it could be done easily over the next 10 years or so. Leo Simpson siliconchip.com.au siliconchip.com.au July 2009  3 MAILBAG Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask SILICON CHIP” and “Circuit Notebook”. Earthing for TV distribution system We recently had a room added to the house which then required a TV outlet. This and the purchase of an HD LCD TV prompted me to replace the motley collection of cable and splitters in my distribution system, which over the years had grown from the original single point to five. I rewired in RG6 cable with F connectors and cast alloy splitters. The improvement in reception is amazing. One of the old splitters had failed on one output and the 5-year old Akai TV in that room had used a “rabbits ears” antenna. When I connected this to the Electronic anti-fouling I am the owner of a yacht which needs anti-fouling to be applied each year to take care of growth on the hull, as does every other pleasure craft. This is expensive but importantly, anti-fouling compounds pollute the marine environment. Recently, a system has been developed which employs one or two ultrasonic transducers attached to the inside of the hull. This system effectively prevents growth from attaching to the hull. This can save boat owners annual bills of over $2000. Now here is the rub: the marketers charge over $5000 for the kit to do my yacht, justifying the price by how much it could save me over time. I have no doubt you could design such 4  Silicon Chip new system, we had 50Hz hum on all radios in the house. When I unplugged the fly lead from the wall socket I felt a tingle when I touched the shroud. I measured the voltage to earth with my Fluke DMM and it was 110VAC. As it could supply no current, the source was obviously high impedance. I have not had time the look at the TV yet to find the cause but it made me think about the lack of any earthing on the antenna system. In the days before live chassis, switchmode supplies and 2-pin mains plugs, the shield on the antenna cable was earthed by its connection to the earthed chassis. Now the whole system a unit at a fraction of the cost if you put your minds to it. This could be of interest to many boat owners who are also into electronics. These units are not yet mass-produced in China and so prices are not reduced accordingly, allowing the “merchants” to employ demand-driven pricing and so make super profits at the expense of “early adopters”. This is where SILICON CHIP comes in. Could you run this as a project in your magazine? Anthony Willis, Koolewong, NSW. Comment: we are very interested in the electronic anti-fouling concept. In the meantime, we are publishing your letter to see if we can get reader feedback on whether it really works. floats above earth so that if a fault connects it to a dangerous voltage, there is no path to cause a protective device, fuse, circuit breaker etc, to operate. I am planning to connect the metal housing of one of the splitters to my house protective earth, so as to provide this path. Phil Andrews, Adelaide, SA. Comment: you would be better off earthing the whole system where the cable connects to the antenna. Earth the antenna as well. A separate grounding stake is desirable. This will also improve noise immunity on digital TV reception. Possible flaw in GPS-Synchronised Clock With regard to the GPS-Synchronised Clock in the March 2009 issue, surely the fatal flaw is that the GPS receiver won’t be able to pick up satellites anywhere indoors. My relatively modern GPS receivers (a Garmin hand-held and Garmin car unit) don’t have a hope of getting satellite signal anywhere in my house where I would want a clock. Am I missing something? Mark Stephens, Brisbane, Qld. Comment: the recommended EM-408 GPS module is extremely sensitive. It works fine in our building which has a steel roof. Even better, it continues to work when placed in a steel filing cabinet! siliconchip.com.au I refer to the new “Dead-Accurate 6-Digit GPSLocked Clock” in the May 2009 issue. Knowing that the NMEA 0183 data stream arrives about 250ms after its appropriate PPS and that the clock is not referenced to the PPS, I’m curious as to what the clock is actually referenced to. I believe the update of the display will be around 250ms late. This is hardly “dead accurate”. Trevor Dalziell, Calwell, ACT. Comment: you are quite correct: there will be a fixed delay of about 250ms between the updated time and “actual” GPS time. There is nothing that can be done about this and anyone building either of our GPS-synchronised clocks will need to resign themselves to being forever 250ms behind real time. GPS-Synchronised Clock web page I have been getting a lot of email on the GPS-Synchronised Clock project so I built a web page with hints and notes to help constructors. It also contains a new version of the firmware which corrected one issue and added some additional features. You can find the page at http://geoffg.net/GPS_Synchronised_Clock.html I thought that you could point people to it if they need help. Geoffrey R. Graham, Perth, WA. Great Value in Test & Measurement GPS synchronised clock is delayed siliconchip.com.au The NEW 350MHz 2/4 Channel Digital Oscilloscope HMO3522/3524  4GSa/s Real time, 50GSa/s Random sampling, low noise flash A/D converter (reference class)  2MPts memory per channel, memory Zoom up to 100,000:1  MSO (Mixed Signal Opt. HO3508) with 8/16 logic channels EV conversion was a beauty I would like to compliment SILICON CHIP on presenting its readers with such a delightful smorgasbord of articles and projects as we have seen these last couple of months. If I had to single out one article that I found particularly enjoyable, it would have to be the one describing Malcolm Faed’s conversion of a Hilux ute to all-electric drive (June 2009). Without question Malcolm deserves to be congratulated for his splendid efforts. How nice it is to see such initiative displayed in an Oz setting. I also liked the article on the battery monitor project in the same issue. There really has been a need for such a project for quite some time. I haven’t as yet had time to fully digest all the good features but from a quick overview this monitor is definitely the sort of thing that every critical battery-operated appliance should be teamed with. As the article points out, batteries are expensive. If I may add to that statement, usually by far the most expensive single component in battery-operated equipment is the battery. Not only do high-capacity batteries contribute a significant part of the initial cost of new equipment, they can represent a very high proportion of the maintenance costs, particularly if the battery charge and discharge cycles are not properly monitored (and controlled), resulting in shortened battery life. On odd occasions, I have been asked to repair vari- Analog meets Digital Sensitivity  Vertical sensitivity 1mV...5V/div. (into 1MΩ/50Ω) Offset control ±0,2...±20V  Trigger modes: slope, video, pulsewidth, logic, delayed, event Accuracy  FFT for spectral analysis  6 digit counter, Autoset, automeasurement, formula editor  Lowest noise fan Quality Simplicity  Crisp 6.5” LED backlit VGA display, 12div. x-axis display range 20div. y-axis with virtual screen function, DVI output  3 x USB for mass storage, printer and remote ctrl. optional IEEE-488 or Ethernet/USB Rohde & Schwarz (Australia) Pty Ltd Unit 2, 75 Epping Road, North Ryde, NSW 2113 sales.australia<at>rohde-schwarz.com July 2009  5 Mailbag: continued More water vapour than carbon dioxide Your recent Global Warming essay (Publisher’s Letter, June 2009) is interesting but you will need to revise your basic stoichiometry if you are to pass this year’s HSC Chemistry exam. You did correctly balance your equation but if you burn two moles (228 grams) of octane with 25 moles (800 grams) of oxygen and “calculate the molecular weights” as you were taught in your chemistry class you would have correctly shown that 704 grams of CO2 and 324 grams H2O would be produced. The reaction does make more moles of water vapour than CO2 and so the gas volume of water vapour is greater than the gas volume of the CO2 but you cannot really say that “there is more water produced than carbon dioxide”. Leo will need to work on biology revision as well. Yes, CO2 is needed for photosynthesis and in a greenhouse increasing the concentration of CO2 will allow the “plants to grow more vigorously”. What you don’t mention is that in most natural ecosystems, particularly in Australia, it is water availability that acts as the limiting factor for photosynthesis, not the CO2 level. Even in aquatic ecosystems where there is high water availability, the extra CO2 from ous kinds of electronically-operated equipment for a non-profit community project that provides low-cost scooters for the elderly and disabled. Far too often have I seen what should have been perfectly good batteries ruined by improper charging (either too much or not enough) or by the batteries being run to their limits before they are recharged. I lay at least part of the blame on the design of the scooters in certain cases, particularly in the case of older machines, which allows the machines to continue running even when the batteries are on the point of exhaustion. Another nag is that some designs employ what users might easily be 6  Silicon Chip burning fossil fuels will probably do more damage than good, as it lowers the pH when it dissolves in water. This pH change will reduce the efficiency of enzymes important in photosynthesis and other reactions. Leo correctly argues that geosequestration is an expensive and energy-inefficient fantasy designed to allow us to keep mining and exporting coal. We do not “really know if global warming is wholly or partially caused by human activity” but we must do everything possible, just in case. I am sure that you would not consider buying a car without seatbelts and airbags just because no one had proved that you were going to have an accident. Dave Dobeson, Berowra Heights, NSW. Comment: the Publisher’s Letter should have alluded to the fact that the volume of water vapour produced is more – not the mass. However, the main purpose was to point out that it is not carbon pollution that is the problem and that water vapour is a major combustion product of the burning of fossil fuels. Carbon dioxide may be a problem but we still don’t know whether human activity is the main cause of the current warming cycle or if indeed, the warming cycle has actually ended. misled to believe are state-of-charge displays but are in fact nothing more than glorified voltmeters. Of course, when batteries, particularly of the lead-acid kind, are fully charged they usually give a significantly higher terminal voltage than when partially or fully discharged. Such displays can be used as rough and ready guides to the state of battery charge provided that the batteries are not heavily loaded. But as you know, every battery, together with any connecting cables, presents a resistance in series with a load. So if you put a voltmeter across the load or even directly across the battery, in an attempt to measure the siliconchip.com.au state of charge of the battery you would be very much disappointed, because the increased voltage drop across load (or battery terminals) due to the series resistance causes the apparent state-of-charge indication to be less than the true state of charge of the battery. An obvious solution is to replace the voltmeter type display with an intelligent one that, in addition to battery voltage, also monitors the charge put into and drawn from a battery and, in addition, compensates for the voltage drop across any series resistance, to give a more reliable indication of state of charge. As a passing thought, some constructors might like to see a scaled-down version of the project; one with, say, just the PC board plus essential on-board components and maybe a bit of extra software programmability (if necessary) to make it easy for someone to integrate the monitor into existing equipment. Another article that I would like to mention is the 10A Motor Speed Controller featured in the May 2009 issue. I particularly liked the idea of sensing the motor current, rather than back-EMF, to control the speed (I wish I had thought of it). There are a couple of questions I would like to ask regarding this controller: (1) Would it be possible to adapt the speed controller, without too much modification, to enable variable torque limiting? (2) Would the speed controller work with the load on the AC side of the bridge rectifier rather than on the DC side as it is now? Herman Nacinovich, Gulgong, NSW. Comment: with regards to your questions concerning the 230V/10A controller, it may well be possible to use the circuit as a torque controller for a particular motor but operating the load on the AC side of the bridge rectifier is problematic as the MOSFET loading arrangements would need to be changed. Response to Publishers’ Letter on global warming With reference to your editorial on global warming in the June 2009 issue, a more correct term is climate change as it actually reflects what is happening. You focused on carbon dioxide as one of the so-called greenhouse gases but the two primary gases are methane and water vapour. These are very important as they help keep the temperature of the surface of the earth within a liveable (for life as we know it) range. As long as there is a balance between the creation and absorption and destruction of these gases, then the amount of energy radiated from the Earth matches the amount received from the Sun. If this balance changes, the result will be climate change. The concept that this will be a general warming is very simplistic. What is actually happening is there is more energy being input into the atmosphere. You mentioned that the concept was just chemistry. No, this is physics, specifically atmospheric physics which is based on thermodynamics. The adding of more energy into the atmosphere does siliconchip.com.au ADVANCED BATTERY TESTER MBT-2LA Features Computes State of Charge for lead acid battery types (SLA, AGM, Gel, Flooded) Test battery condition – quickly and easily identifies weak or failing batteries Patented high accuracy Pulse Load test – battery safe, non-invasive Test 2-volt, 4-volt, 6,volt, 8-volt, 12-volt Measures battery performance under load, not just voltage or internal resistance Ideal for battery management & cell matching – reduce costs and increase reliability Description The MBT-LA2 provides a comprehensive means of testing the state of charge and battery condition for 2-volt, 4-volt, 6,volt, 8-volt and 12-volt lead acid battery types (SLA, AGM, Gel, Wet). Lightweight, compact design make it an ideal tool for anyone working with lead acid batteries. The microprocessor-controlled instrument tests popular batteries using a patented, high-accuracy pulse load tests. After a fully automatic test cycle, percentage of remaining battery capacity is indicated on the LED bar display. Test results are easy to understand. An integrated cooling fan dissipates heat from testing, and the circuit is protected against over-voltage. Rugged NBR rubber sleeve protects against impact. Includes 48" removeable test leads with sold copper clamps. The accessory kit (K-MBTLA2) includes a hanging strap & magnet for hands-free operation, and a protective soft case. Requires 4AA batteries (not included). Applications ŸFire/security ŸUPS ŸMedical ŸIndustrial ŸLighting ŸTelecom ŸMobility ŸInspection ŸMilitary ŸSafety ŸService ŸIT ŸAccess control ŸAuto/marine/RV ŸManufacturing ŸUtilities For more information, contact SIOMAR BATTERY INDUSTRIES (08) 9302 5444 or mark<at>siomar.com July 2009  7 Mailbag: continued not mean a general warming. An example is the lighting of a fire in a fireplace in a house. The immediate area is warmed but the rest of the house will cool down as cold air is drawn in to replace the air drawn up the chimney, so if you average out the whole temperature in the house it may actually show a drop. The additional energy in the atmosphere will show as an increase in the frequency and severity of weather events such as cyclones; it will also cause a shift in weather patterns such as the monsoon, El Nino and La Nina, which in turn can cause excessive precipitation in one area and drought in another. It will be interesting to see over the next few years how the Caribbean & Gulf of Mexico hurricane seasons shape up; will there be an increase in the number of category 5 storms? Will this be matched with a similar increase in the Bay of Bengal? 8  Silicon Chip As you mentioned, CO2 is absorbed by plants. The problem we have is not only are we emitting more, we are also clearing the forests that would be active in the absorption process. The concept that the excess CO2 can be dissolved in the ocean might work but this would slightly increase its acidity, which has the potential to affect anything that uses calcium carbonate as a shell or skeleton. It is very easy to deny climate change but by the time it becomes totally obvious it will be too late. How many 1-in-100 year events will it take to prove it exists? The first sign will probably be from the insurance industry, as they will be watching the increased number of claims. Laurens Meyer, Richmond, Vic. Leo Simpson comments: you have drawn conclusions from my editorial which are not justified. Carbon dioxide and “carbon pollution” is what politi- cians and environmentalists are focussing on. They are essentially ignoring methane and water vapour although the proposed Australian Emissions Trading Scheme will penalise graziers because their sheep and cattle emit methane. This is insane! I was focussing on the burning of fossil fuels, not the existence or causes of methane. If you want more authoritative information on whether climate change is caused by human activity, you need to read Ian Plimer’s book entitled “Heaven & Earth; The Missing Science”. He does not deny climate change and nor do I. I just don’t think that humans have anything to do with it. The energy produced and used by humans may seem incredibly large but it is vanishingly small when compared to the total energy input from the Sun. Even a very slight variation in solar output will completely overwhelm anything that humans do. The Sun’s output does vary significantly and does have a major effect. Consider the Mediaeval Warming and the Little Ice siliconchip.com.au Age and other major global climate variations which have occurred in the last 2000 years and right back to the beginning. Man’s presence has had no effect. Disputing the Publisher’s Letter At the risk of seeming “hysterical”, Leo Simpson’s Publisher’s Letter in the June 2009 issue cannot go without comment. Leo attempts to give us a simple chemistry lesson and then to use that to berate those ignorant “greenies”. The first problem is his lesson is wrong. The equation in his letter (2C8H18 + 25O2 => 16CO2 + 18H2O) means that by mass (ie, calculating the weights as asked) 16 * (12 +(16*2)) = 704 grams of CO2 are emitted vs 18 * (1*2 + 16) = 324 grams of water (I’ve rounded the numbers). Leo then makes the false and irrelevant comment that the mass of water being released from combustion is more than the mass of CO2 and that therefore CO2 is not a problem. This is equivalent to saying we only need to know one property of electrical components when deciding their importance OR function. Water is the most significant greenhouse gas in the atmosphere. Those greenies called atmospheric scientists are well aware of this. But the global atmospheric water balance is largely unaffected by direct human action and is dominated by the dynamic equilibrium between solar-driven evaporationtranspiration and precipitation. The average lifetime of a water molecule in the atmosphere, where the bulk of the water is below the stratosphere, Reaction to Puppy Linux I’m an old IT buff, pretty up to speed on Windows but I was very attracted to try your Puppy Linux installation in the March 2009 issue. I have a Sony Vaio PCG-R600 which was my main laptop for a few years, since replaced by a much faster Toshiba. Everything in the Sony was working but WinXP had slowed down incredibly, in spite of all the tweaks and scrubs of several maintenance programs. So I followed your instructions to the letter. I downloaded the latest version of Puppy on my BIG desktop, burned the CD with your recommended ISO file burner and tried to boot the Sony with the CD. Nothing! After searching for hours I finally found a clue: install hangs with SATA CD drives, not with IDE CD drives. I then used an outboard CD drive, which got me further down the track. However the install still hung. There is a work-around by putting the three vital Linux files on a thumb drive and completing the boot from there. So, very elated in spite of the huge frustrations with the SATA drive, I decided to install the HD boot option and chose “Frugal” install. All went well until I got to GUMP. Making the changes to the GUMP execute is eight days. Carbon dioxide has an atmospheric lifetime of decades. I shouldn’t need to point out that CO2 and H2O, being different molecules, unsurprisingly have different infrared spectra (http://en.wikipedia. org/wiki/File:Atmospheric_Trans- text file felt like changing something in WIN registry, so I checked and double-checked before hitting “return” at each input. My Linux partition was sda5 so I was careful to input the correct drive and partition details. Everything completed and I re-booted the PC from the HD. Boom, end of story, the “Kernel / puppy400/vmlinuz pmedia=idehd psubdir=puppy400” hung with “file not found”. I went back and changed every possible parameter (pmedia=satahd, idecd, sata cd, you name it) but no luck. And I’m STUCK in GUMP – no way to go back to the BIOS program, no way to get back into Puppy, I am GUMPED for life! I searched for further hours and hours on the posts, Puppy search etc. Nothing! So I’m afraid that my experience has been a complete waste of two days’ time. Next move? Wipe the HD and do an XP reinstall. And forget about Linux (again – I tried a couple of years ago with similar results). Mate, if it installs without hiccups, it’s brilliant but once you get into the Linux coding side, it isn’t for the faint-hearted! John Nixon, Optical Network Engineering, Auckland, NZ. mission.png). We use this property in instruments to measure one in the presence of the other and it is this same property (in conjunction with the mass and lifetime) that is important when we determine the relative greenhouse effect of the two. In the link above we You wear multiple hats. Shouldn’t your scope? The new Agilent Infiniium 9000 Series oscilloscopes are engineered for broadest measurement capability. You never know what your next project will require. That’s why we designed the new Infiniium 9000 Series to be as versatile as you need to be. Agilent Infinium 9000 Series Oscilloscopes Bandwidth: 1GHz, 2.5GHz, 4GHz Channels: 4 analog + 16 digital on MSOs Sample rate:10GSa/s Memory: 10M --1G Display: 15" XGA Footprint: 33 x 43 x 23mm (h x w x d); 11.8kg Phone: 1800 629 485 View online demo at www.agilent.com/find/9000family siliconchip.com.au July 2009  9 Mailbag: continued see that the spectra for CO2 fills in some absorption gaps for water. Leo also made the true but irrelevant comment that water and carbon dioxide are both essential to life; the implication being that they are therefore harmless. This is like saying that since voltage and current are essential for the functioning of a circuit, we can ignore the danger imposed by 1kV <at> 1A, as we all know that 1V <at> 10mA is “harmless”. The dose makes the poison. Another element that is essential to life is selenium but only at trace amounts: swallow a gram or two and you will suffer. The argument is frequently put that more CO2 means plants grow better. This may be true in a greenhouse but in the real world it means more than that. Photosynthesis comes in several flavours and different plants have different mechanisms (C3, C4 & CAM) for taking up CO2 – the initial step. Thus some plant species may be favoured over others. But, the so-called CO2 fertilisation effect also depends on temperature, nutrients and water. Increases in temperature can remove any benefit from the increased CO2 concentrations. Climate zones can move but soils do not. If climate zones do move, will they fortuitously align with regions of high soil fertility? And what of water – a question very pertinent to Australia? Moving on to the statement “Nor do we really know if global warming is wholly or partially caused by human activity”. This is the Plimer argument. If the increase in CO2 concentration was the only evidence at hand, one could argue for other sources of that CO2. But we also have the isotopic signatures of carbon that comes from volcanoes, carbon that comes from fossil fuels and the carbon in the atmosphere. On top of that, we also have measurements of the O2 concentrations – which are falling in line with the carbon increases thus suggesting combustion. How do volcanic emissions of CO2 reduce O2 levels? The evidence is clear. It’s “us wot done it”. Even if you dispute that increased levels of CO2 don’t automatically mean the temperature will increase like Svante Arrhenius (a notable chemist and apparently a greenie before his time) suggested, another issue is the decrease in the oceanic pH that increased levels of CO2 are causing! A mixed blessing. For while the oceans continue to absorb CO2 it slows the rate of increase in the atmosphere – but at the expense of the ability of shell fish and corals to create their shells. One day the oceans will no longer absorb as much CO2 and then the trouble really starts – that’s not being hysterical, it’s a statement of chemical fact. We know the constants that describe oceanic equilibria. While I agree with Leo’s scepticism of Carbon Capture and Storage (it’s a sop to the coal mining industry), articles and letters like this devalue the magazine. I suggest either consultation with real experts in the field or the purchase of an excellent reference like “Earth System Science: From Biogeochemical Cycles to Global Change”. Anything by frustrated mining geologists near retirement should be returned to the remaindered bin. Am I hysterical? Shane Perryman, Margate, Tasmania. Comment: if you have a look at the volumes of gases released in the combustion of octane, there is more water vapour than carbon dioxide. In any case, carbon pollution is not the problem. Maybe we do have a problem with carbon dioxide but that is still unknown. Doubling the “dose” of carbon dioxide probably won’t have catastrophic effects. You cannot simply reject an argument because it has been put forward by Ian Plimer (and others). He could well be correct or he might be wrong – we don’t know at this stage. Do you dispute the previous warming cycles when man had nothing to with it? Australia’s Best Value Scopes! Shop On-Line at emona.com.au GW GDS-1022 25MHz RIGOL DS-1052E 50MHz RIGOL DS-1102E 100MHz 25MHz Bandwidth, 2 Ch 250MS/s Real Time Sampling USB Device & SD Card Slot 50MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling USB Device, USB Host & PictBridge 100MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling USB Device, USB Host & PictBridge Sydney Brisbane Perth ONLY $599 inc GST Melbourne Tel 02 9519 3933 Tel 03 9889 0427 Fax 02 9550 1378 Fax 03 9889 0715 email testinst<at>emona.com.au 10  Silicon Chip ONLY $879 inc GST Tel 07 3275 2183 Fax 07 3275 2196 Adelaide Tel 08 8363 5733 Fax 08 8363 5799 ONLY $1,169 inc GST Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au EMONA siliconchip.com.au CHINA PCB Supplier Confusion over Freeview digital TV using yellow (video) red (R audio) and white (L audio) RCA connections into a simple video switch. I’ve been listening to media pubAll of this involved some nifty inlicity on the introduction of digital stallation techniques, such as housTV but the information given raises ing the projector in a wall cavity with more confusion; for example, “look the lens aperture normally masked for the Government sticker on set by a framed print which slides across top boxes.” Presumably, that means on a track. The projected image the designated boxes1are compatible -layer up to 30-layer might be standard definition and with whatever. Anything else is Cost and quality I could worry about HDMI leads incompatible? time deliveryand the like but I am enormously I made an enquiryOn to the “Digital impressed with the quality of the TV Task Force” regarding a new service SD Dedicated picture on this large 2.5-metre screen set-top box which I purchased in Online Quote & Order and the sound is great too! haste some time ago Instant - now residing ...........DayBrian and Night Graham, in a cupboard, unused. The purchase was made just priorOto neconnecting piece orders are wvia elcemail. ome! to Foxtel cable TV, of course with Check our low price anComment: d save big $right $$ now there are only three extra digital channels with diftheir own box. But when digital TV ferent programming to the existing arrives, why not connect this SD box SD (and analog) channels: ABC2, to our old CRT TV set, forgoing the SBS2 and Ten’s One HD. Most wonders of HD (which I may have programs on ABC2 are repeats of trouble in distinguishing anyway, shows on ABC1 but there are some because of deteriorating eyesight)? worthwhile additional programs to I am getting little sense out of the be seen. SBS2 has only just started “Digital TV Task Force” have web:and www.pcbcore.com broadcasting and will have a mixsuggested to them email: that theysales<at>pcbcore.com should ture of sport and other programprepare advisory information to phone: enquiry 86(571)86795686 ming. One HD is great if you like cover the sort of (dumb?) lots of sport. I made. I would guess there would Later on, there will be a children’s be millions of Australians who are TV channel called ABC3. Some time equally confused. This information later there might be a couple of othshould be the subject of a national ers. There certainly will not be 15 letterbox drop, prior to introduction extra channels although there is a of the new TV format. selection of data channels which However, to be more practical, it carry low-resolution video. occurs to me that perhaps SILICON You need a HD set top box if you CHIP is preparing an article to do want to watch HD channels on your exactly what I had suggested to the analog TV. Unless you have a large Task Force. This material should be HD TV or a HD projector and very valuable help for many. keen eyesight, you are unlikely to While all of this wonderful technotice any difference between HD nology is advancing on us, I’ve built and SD broadcasts. Both HD and SD my own (invisible!) home cinema in broadcasts do have a big advantage my living room, with a video projecin that they eliminate noise and tor and a large pull-down screen. ghosting in the picture. This is very simply coupled to my We agree with your comments video source (DVD/VCR player, about projectors and large screens. cable TV, free-to air or whatever) For overall impact, a video projector and (prior to 5.1 surround sound) a cannot be beaten. simple stereo sound system, simply . . . . . AWA 893P portable transistor radio prototype thru production I suppose you have already been notified but just in case, the radio featured in this month’s Vintage article (June 2009) is definitely an AWA 893P not a 693P. The number can be plainly siliconchip.com.au seen in the interior pictures. I have two of these and I am very pleased with them. See my website at http://transistor. bigpondhosting.com/awa_893p.html Ian Malcolm, SC Scoresby, Vic. CHINA PCB Supplier prototype thru production . 1-layer up to 30-layer . Cost and quality . On time delivery . Dedicated service . Instant Online Quote & Order ...........Day and Night One piece orders are welcome! Check our low price and save big $$$ web: www.pcbcore.com email: sales<at>pcbcore.com phone: 86(571)86795686 AMALGEN TECHNOLOGIES PTY LTD the most experienced Toroidal Transformer manufacturers in Australia Manufacturers of the original ILP Unirange Toroidal Transformer - in stock from 15VA to 1000VA - virtually anything made to order! - UPS, power conditioning and surge suppression too Amalgen Technologies Pty Ltd Ph: (02) 9570 2855 Fax: (02) 9580 5128 email: sales<at>amalgen.com.au web: www.amalgen.com.au July 2009  11 The Magic of What do Perth, Saudi Arabia and cruise ships have in common? They all rely on desalination for fresh water. And the Gold Coast, Sydney and Adelaide are about to join the club! by Geoff Graham T urning salty water into fresh, drinkable water is not new. In the early Australian gold rush days large areas of woodlands were stripped to feed “condensers” that boiled salty water and trapped the condensation for sale to thirsty miners. These days a large cruise ship will generate over a million litres of water a day from the sea using either flash evaporators or reverse osmosis, while Middle East countries such as Saudi Arabia produce over 70% of their drinking water using various forms of desalination. Australia is not left out. The advent of a drying climate has triggered a flurry of desalination plants either planned or under construction with the first in Perth, Western Australia, running since 2006. There are a number of technologies used for desalination but most modern large scale plants are based on reverse osmosis. These plants are expensive to build but, in the longer term, cheaper to run. This technology is quite recent – it only got its start in the 1970s and 1980s when efficient reverse osmosis membranes were first manufactured in quantity. In Australia Small desalination plants have been operating across Australia for many years, providing drinking water for towns such as Penneshaw, Coober Pedy and Marion Bay in South Australia. The new plants on the drawing boards are on a much larger scale and represent a major infrastructure investment. In total six plants are running or currently planned. All are destined Fig.1: the layout of a typical desalination plant. It looks simple – salt water is filtered and passed through the reverse osmosis process. However, as with most things, the reality is more complex with the magic happening in the reverse osmosis section. (courtesy Sydney Water) 12  Silicon Chip siliconchip.com.au DESALINATION Part of a $2 billion project, this aerial picture (taken in March 2009) shows the Sydney Desalination Plant, currently under construction at Kurnell. It is now more than 80% complete, with mechanical and electrical work well underway and will become operational this coming summer. (courtesy Sydney Water) to serve major population centres and will supply a significant amount of our water needs. The first was a plant at Kwinana, south of Perth, built three years ago for the WA government by a French consortium. A similar plant, built by another French consortium, has just been completed on the Gold Coast. Sydney is not far behind with a monster plant nearing completion at Kurnell that is planned to supply 15% of the city’s water requirements. Others preparing for construction include a second plant for Perth and the first plant for Adelaide, at Pt Stanvac, both of which will be built by separate Spanish consortiums. Finally, Victoria is in the early planning stage for an installation on the Bass Coast near Wonthaggi. Desalination is not cheap. The Perth plant cost $387 million to build in 2006 while the Sydney plant is expected to cost almost $2 billion, including the connecting pipeline. The amount of water produced is large by any measure. The Perth plant produces 130 million litres a day while Sydney is projected to produce 250 siliconchip.com.au million litres of water each day. A typical plant On paper a desalination plant looks relatively simple. You suck seawater in, filter it to remove sand etc and then pass it through reverse osmosis membranes to obtain your clean water. As always, the complications lie in the details. The inlet system is where the process starts. Typically a plant will suck in 20 million litres of water an hour through large concrete intakes on the Fig.2: osmosis occurs when water migrates through a permeable membrane towards the more salty solution. The level on the less salty side will then decrease. seabed. This is an enormous amount of water and you might think that it could also suck in fish and other ocean life, even including someone who was enjoying a cooling dip. This cannot happen because the inlets have grates across them and are designed with a very large intake area to keep the flow to less than 0.1 metre per second. At this rate the flow is less than a typical ocean current and does not affect marine life which can swim around the inlets as normal. The water then goes through screen- Fig.3: reverse osmosis occurs when pressure is applied to the salty solution forcing the water through the membrane to the less salty side. July 2009  13 ing and filtration stages to remove sand, algae and similar impurities. The technology varies but typically, as in the case of the Perth desalination plant, sand filters are used. These are a similar technique to the sand filter used in a home swimming pool. All this is normal technology but the water then enters the high-tech reverse osmosis section where the magic begins. Reverse osmosis Reverse osmosis can be best explained by looking at the phenomenon of osmosis first, then explaining the reverse part. Osmosis is the ability of water to migrate through a permeable membrane while leaving dissolved components behind. This can be observed with two solutions, one saline and the other not, separated by a suitable membrane. By osmosis the water will move slowly through the membrane from the less saline solution to the more salty solution. Contrary to what you might first assume, this action will raise the level of the salty water above the level of the less salty solution (see Fig.2). Membranes are common in nature; your skin is a membrane and water will move through it via osmosis while you are sitting in the bath. Reverse osmosis, as implied in its name, is the reverse of osmosis and occurs when you force the water through the membrane in the opposite direction as shown in Fig 3. The pressure applied to the salty side must first overcome the tendency of the water to move via osmosis to the salty side. Then, with increasing pressure, the water will reverse direction towards the less saline side leaving the salt behind in the increasingly saline solution. Special membrane This process requires a special type of membrane that is permeable to water but not dissolved salts. It is Reverse Osmosis pressure vessels. Each contains seven reverse osmosis membranes tightly wound in coils. The pressure used to force the water through the membranes is vey high, up to 1000 psi. At this pressure salt water is very corrosive so high quality stainless steel is used (courtesy Water Corporation WA). tempting to think of the membrane as a fine filter which traps larger particles (salt) while letting water through - but that is not correct. The osmosis mechanism is not fully understood but one explanation is that the water works its way through the membrane by packing into an ice-like A Serendipitous Discovery In 1959 Sidney Loeb was researching for his master’s thesis with Srinivasa Sourirajan when together they discovered the first practical membrane for reverse osmosis. That discovery is credited with being the foundation of modern desalination technology. While working on membranes in their laboratory they hit upon a formula which was an unexpected success in that it allowed a practical flow of water while stopping most salt. 14  Silicon Chip structure (at room temperature) and “melting” away on the other side. The ions from the salt cannot fit into the ice-like matrix and get left behind. Unlike a filter, in osmosis it is not the membrane pore size or the particle size that matters. Osmosis itself was first observed But a second test (from the same sheet of membrane) did not work. Subsequent tests were either good or bad “as if flipping a coin” according to Dr Loeb. Finally they figured out that the membrane was anisotropic (directionally dependent). The side facing the air when the membrane was cast on a glass plate had to be installed in contact with the saline solution to work correctly. In Dr Loeb’s words, “I sometimes wonder if I would have continued testing that membrane sheet if the first test had been a failure.” siliconchip.com.au Fig.4: the construction of a reverse osmosis module. The clean water permeates through the membrane and collects in the centre while the water that does not pass through (the concentrate) carries away the salt and other impurities. (courtesy Water Corporation WA) 250 years ago and since then researchers experimented with reverse osmosis. Despite these efforts, reverse osmosis remained a curiosity because the water flow through the membrane was so low that the process was impractical for large scale use. The breakthrough came in 1959 when Sidney Loeb and Srinivasa Sourirajan in the USA discovered a membrane that was much more efficient (see the sidebar A Serendipitous Discovery). The modern membrane used in reverse osmosis is a wonder of materials science and is normally a thin-film, composite membrane consisting of a thin polymer barrier layer formed on one or more porous support layers. Membranes have different characteristics and it is common for desalination plants to need two stages of reverse osmosis to remove everything. For Fig.5: this diagram better shows the flow of water to the centre of the membrane coil. The outer porous layer allows the salt water to flow over the surface of the membrane. Water that passes through the membrane then flows via the inner porous layer to the centre where it is drained. (courtesy Water Corporation WA) example, the first stage will remove salt while the second targets boron or in some cases, bromide. The pressure vessel The membranes sheets are wound into large rolls held inside pressure vessels. These vessels are the long (generally white) tubes that you see in a photo of a typical desalination plant. Inside a pressure vessel the sheets of membrane are rolled up (see Fig.4) with the desalinated water (permeate) collecting in the central spine. At least half of the intake water does not go through the membrane but instead runs out and is eventually discharged back into the sea. It is this flow of discarded water across the membranes that keeps them clean and prevents them from clogging up as a sieve would. As shown in Fig.5, the membrane A sea water intake. A desalination plant can suck up to 20 million litres per hour but the design of the intakes ensures that the flow into the intake is mild enough to have little effect on marine life (including divers!). (courtesy Water Corporation WA) siliconchip.com.au spiral is separated by a porous material that allows the seawater to contact every part of the membrane with an inner porous layer allowing the clean water (permeate) to flow to the centre. A pressure vessel would hold a number of these rolled membrane sheets and a typical plant would use almost 20,000 membranes at a cost of about $1,000 each. Nothing in desalination is cheap. Long Term Trend You would have to be a hermit or living overseas, if you did not know that Australia is in a prolonged period of drought. Falling rainfall levels and rising water consumption across Australia have reduced the level of water in our dams and forced our politicians into making some expensive decisions. The trend is most apparent in Western Australia where the inflow of water to Perth’s dams has been steadily falling over the past 50 years to one third of the previously typical levels. To make it worse, demand has increased by three times during this same period. Perth introduced its first water restrictions in 1960 and tapped into other sources such as groundwater but the trend has been inexorable. Three years ago the state government built Australia’s first desalination plant, the largest of its kind in the southern hemisphere and now a second plant for Perth is about to start construction. Sydney and Melbourne felt the effects of the big dry later but their dam levels have also been steadily falling since 1998. With traditional sources of water such as new dams being ruled out for environmental and other reasons planners across the country are turning to desalination. July 2009  15 This installation uses six high pressure centrifugal pumps drawing 2600kW each and pumping 1144 cubic metres/hour. They are made from super duplex stainless steel and need to be very well balanced during installation. Manufacturer was Clyde Pumps in Scotland. (courtesy Water Corporation) Recycle Instead? Another approach to the crisis is to recycle water. The technology used in recycling is similar to desalination – you filter the water to remove the big stuff and then use reverse osmosis to remove everything else. In planning for the Sydney desalination plant Sydney Water made a detailed comparison of the two systems and the differences are instructive. The cost of building identical capacity plants was about 50% higher for the recycling plant with the running costs also more expensive. This makes sense if you think about it. Both desalination and recycling take in dirty water and clean it but recycled water is dirtier and needs more cleaning. Also, salty water is easier to get; you just suck it in from the ocean, whereas water for recycling must be piped from the sewage plants. Apart from the cost, it is difficult to sell the notion of recycled water to the public, so it is no wonder that the planners chose desalination. 16  Silicon Chip Due to the spiral construction the membrane does not rupture under pressure but rather is slowly compressed. It is this compression which limits the life of a membrane which is about five to seven years. During its lifetime the performance of each membrane is monitored by measuring the flow rate and testing the quality of the desalinated water. Membranes are also cleaned two to three times a year using caustic, acid and detergent solutions. Practical issues The principle of reverse osmosis works well, but implementing it in a plant that must produce millions of litres a day is not easy. To force water through the membrane enormous pressures are required. In the Perth desalination plant there are six large centrifugal pumps which move millions of litres an hour at pressures up to 70 bar or in layman’s terms, about 1000 psi. These are made from super duplex stainless steel and must be very well balanced during installation to cope with the high speeds involved. Each consumes 2600kW, enough electricity to power hundreds of homes (see the sidebar Where Does the Electricity Come From?). The energy used to drive the pumps is a large part of the cost of running a plant, and for this reason a lot of attention is paid to energy efficiency. The water that passes through the membranes loses its pressure on the way through. However, the salty water destined for discharge retains the high input pressure and rather than let that energy go to waste, a modern desalination plant tries to recover as much as it can. The technique used in many plants is called isobaric or “pressure-equalising” energy recovery. This technology works by allowing the high pressure water to directly contact and push against the incoming water in pressure equalising or “isobaric” chambers. These chambers are inside spinning rotors that limit the contact time to avoid mixing; the result is a stream of high speed hammer blows against the incoming stream that transfer most of siliconchip.com.au Isobaric or “pressure-equalising” energy recovery devices. These transfer the energy contained in the discharge water to the incoming water and can reduce energy consumption by up to 96%. Inside each cylinder is a high speed spinning rotor made from tough ceramic that allows the outgoing water to hammer against the incoming water and thereby transfer the energy. (courtesy Water Corporation) The only time it will be stopped is for maintenance and environmental reasons (for example, the salty outflow is not dispersing). Even in these circumstances the plant maintains a small output by continuously rotating a small production through each bank of membranes to prevent a full shutdown being forced on them. Discharge the energy held in the outgoing stream. The energy recovery can be as high as 96% although in practice the actual percentage is rather lower. Regardless, this efficiency makes a huge difference in the amount of electricity required to drive the high pressure pumps and therefore the plant’s running costs. Another issue in plant design is corrosion. As anyone with a boat knows, sea water is very corrosive and at the high pressures used for reverse osmosis, it is positively destructive. As a result high grade stainless steel and ceramics are used in many places and this is part of the high price tag of a desalination plant. Starting and stopping a plant can take some time (up to a day) and the membranes need special preservation arrangements to prevent damage when not being used. Accordingly, the engineers like to keep the plant running continuously at full capacity. The water discharged from the plant is about double the normal salinity of sea water and this could be a problem for marine life if it was simply dumped back into the sea. Some sites, such as the Gold Coast and Sydney, can rely on strong ocean currents to help disperse the salty water but other locations are not so convenient. For example, the Perth plant discharges into Cockburn Sound which does not have strong currents. Because of this the outlets were designed to Where Does the Electricity Come From? Former NSW Premier, Bob Carr, once famously dismissed the whole idea of desalination as “bottled electricity”. Desalination can be thought of as: salt water + electricity = drinking water On average it takes about 5kWh of electricity to produce one thousand litres of fresh water. For plants producing millions of litres this adds up to a lot of electricity. As we do not want to compound the environmental effects that are blamed on burning fossil fuels, renewable energy is a popular source for the electricity. Consequently Perth, Sydney and others have decided to go with wind farms. As with the renewable electricity that you can purchase at home, the electricity for desalination is drawn from the general power grid. However, it is purchased at a higher than normal price, even if the wind farm is becalmed at that time. The extra money is then paid to the wind farm when they do generate some electricity and feed it into the grid, as that means that less power is required to be generated from fossil fuel. The result is the same as transmitting the power directly to the desalination plant but avoids the cost of building a duplicate transmission system. The Perth desalination plant has a continuous power draw of 24MW and this is nominally supplied by the Emu Down Wind Farm located 100km north of the city. This facility cost $180 million siliconchip.com.au to build and has 48 wind turbines capable of generating a peak 80MW of power. 40MW of that is reserved for the desalination plant which, given the variability of wind power, means that the desalination plant will end up paying for the equivalent of 24MW of continuous renewable energy. For the Sydney desalination plant a wind farm will be built at Bungendore (near Canberra), with a capacity of 140MW. The second desalination plant for Perth will go one step further with 20% of its power to come from what is called “speculative energy sources”. This covers technologies such as geothermal, wave power and other experimental sources and accordingly an even higher price will be paid for this electricity. July 2009  17 sources of water (such as dams) on days of light water consumption to favour water from the desalination plant. In extreme cases they will even pump the desalinated water into dams for storage. As the overall aim of the desalination plant is to conserve the water in our dams this arrangement will even out in the long term. In the unlikely event that the dams approach overflow the desalination plant would then be shut down, probably for a long time. The overall cost of desalinated water can vary considerably, depending on many factors, but it is still affordable. When constructed the Perth plant had running costs of about $20 million per year and the cost of water produced was close to $1.20 per kilolitre. This can be compared to the cost of water from traditional sources at the time of 80c to 90c per kilolitre. Other plants currently under construction have projected production costs that range from $1 to $3 per kilolitre. If you are in a serious situation like Adelaide, even that price is a bargain. With so much effort going into producing the water in your tap, you should appreciate a glass of water SC even more. The salty discharge water on its way back to the ocean. The salt level is double normal levels but it quickly disperses in the ocean. In the background you can see the sand filters that are used to clean the incoming sea water by removing large particles such as sediment and algae. (courtesy Water Corporation) shoot the outflow upwards from the sea bed to encourage mixing. Before construction this design was tested by the University of NSW in a large swimming pool. Overall, the designers aim to mix the outflow to such an extent that the salinity of the water reaches normal levels at 50 to 75 metres from the outlets. Drinkable water The water produced by reverse osmosis technology is essentially pure but still needs processing. So a desalination plant must include a post 18  Silicon Chip treatment stage which adds components such as fluoride that we expect in out drinking water. This stage also adds alkalinity to the soft processed water. A similar treatment stage is used for soft dam waters as this prevents corrosion in the distribution system. In keeping with other treatment methods, chlorine is also added for cleansing and maintenance of the distribution system. Finally the water is fed into the municipal water reticulation system. Because the plant is run continuously the engineers will throttle back other Monitoring buoys are used to monitor salt concentration, dissolved oxygen and many other parameters. If these exceed safe levels the desalination plant will be shut down until the ocean currents can return the sea water to acceptable levels. (courtesy Water Corporation) siliconchip.com.au 1 2 3 4 5 6. . . NOW AVAILABLE: SIX MONTH SUBSCRIPTIONS & AUTO RENEWALS In these tough economic times, we understand that taking out a one or two-year subscription may be difficult. Or perhaps you’d like a trial before committing yourself to a full sub. Either way, we’ve made it easy with our new six-month subscriptions. 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CONVENIENT AUTOMATIC q MasterCard SUBSCRIPTION RENEWAL: Your Name____________________________________________________________ q Tick here if you’d like us to automatically renew your subscription Card Expiry: siliconchip.com.au siliconchip.com.au Signature______________________________ THIS PAGE MAY BE PHOTOCOPIED WITHOUT INFRINGING COPYRIGHT    as it elapses (ie, 6 month, 12 month or 24 month).    We’ll renew until you tell us to stop! July 2009  19 July 2009  19 Two cost reco He’s held onto a large library of VHS tapes for decades so Barrie Smith thought he could make good use of the Easter break by engaging with DVD recording. Here are his reactions to a Tevion DD1018 and an AWA DR711 DVD recorder. I t was very much due to our Prime Minister’s urging to ‘spend, spend, spend’ that I fell upon the ALDI catalog with gusto: a DVD recorder for $99! Zipping down to the local ALDI on Easter Saturday, I laid down the plastic and helped the economies of three countries in one swoop: China as the makers, Germany (who own the retailer ALDI) and hopefully, a band of Australian staffers working for the latter. Before getting on to the main topic, I’ve noticed that something funny has been going on in the retailing of disc recorders: there are heaps of DVD recorders with 80/160/250 Gigabyte hard drives as their primary storage and selling for $400-500, with a solitary model at $299. Parallel to this you can get your hands on a couple of Blu-Ray recorders from Panasonic, with prices starting at around $1600. So I felt the arrival of the low-cost Tevion DD1018 was a significant event. Looks and Feel The unit is a neat package in black with external controls placed on the upper edge. A drop-down front panel gives access to composite audio and video inputs, along with a camcorder DV input. 20  Silicon Chip Round the back we face a whole complex of in/outputs: RF in/output loop; composite audio/video in/outputs along with an S-Video output; component Y, Cb/Pb, Cr/Pr inputs are there as well as a pile of audio ports for Dolby 5.1 channel outputs. The remote control does a sterling job by expanding the options via 50 buttons (of which ten are channel numbers) with choices of front or rear composite inputs plus RF, audio volume up/down buttons, all the usual DVD navigation tools, channel selection via the internal analog tuner as well as a timer to record time shifted programs … the Tevion can also ‘one touch’ record at any time. The on-screen menus are well set out and copious in variety. However, due to the nature of DVD and its multiple skills and requirements, you do need a fair amount of study to get it going. This is how I and my teenage son spent Easter Sunday; logging the channels into the menu, assigning program positions and making many test recordings. Little did I know at this stage that this exercise would need to be repeated twice more. Single Layer The Tevion replays DVDs containing NTSC/PAL programming and CD-R/RWs with AIFF and MP3 tracks. Discs with JPEG images are OK as well as Picture CD material, Video CDs, Super VCDs, HDCD and MPEG4. It will also record SD video to Single Layer DVD+/-RW and DVD+/-R media. It will not record to Dual Layer DVDs … but that’s OK I guess, because the recording options are wide. The recording quality choices are shown in the table below, with the highest quality (and shortest time) at the top. QUALITY LEVEL RECORD TIME MBPS RESOLUTION (hours) (MPEG2) HQ High Quality 1 9.716 D1 SP Standard Play 2 5.037 ˝ LP Long Play 3 3.382 LP EP Extended Play 4 2.537 ˝ SLP Super Long Play 6 1.691 SLP ENCODING CBR CBR + VBR ˝ ˝ ˝ siliconchip.com.au o lowDVD orders Review by BARRIE SMITH Early on, I had difficulty in reading the washed-out on screen menu but did eventually work my way through the options. The timer menu was an easy one and compared to VHS machines, offered far more elegant ways to time shift than Ye Olde tape machine. After you choose channel number, date and time of recording commencement you then have only to select the length of recording in hours and minutes taking care to choose the recording quality that will comfortably encompass the record time. Of course, the Muggins way is to select SLP, which gives six hours of recording but at the lowest quality. Thinking users will naturally juggle record time and quality level in their decision-making. Post recording, you must finalise the DVD, with both DVD-R and DVDRW discs. Doing so enables the disc to be played on any other compatible machine, just like a commercial DVD. But doing this changes the disc format so that you can no longer record to it, turning it into a ‘play only’ disc; this makes a DVD-R no longer writeable. By using a DVD-RW platter you can still finalise the disc for replaying in another player, then return it to the Tevion, ‘unfinalise’ it, remove the exsiliconchip.com.au isting programming and accumulate extra recordings, much in the way of Ye Olde VHS but with the attractive advantage of replay access in a random fashion, via on screen icons indicating the programs on offer. It’s a great way to travel! I didn’t get into DVD+R/RW discs; for one thing they are far more expen- sive than DVD-R/RWs and don’t seem to offer any advantages. Back to recording: after you’ve committed pictures and sound to a disc, and before finalising, there is an option to rename the text that accompanies the program icon: you get only 11 characters but I found this is more than enough for an ID. There is The Tevion DVD recorder is styled in black with external controls on the upper edge. A drop-down door reveals the standard yellow (video) and red/ white (stereo audio) inputs along with its DV input. The Tevion’s rear hookup panel has a host of inputs and outputs, including a duplication of the video and audio inputs from the front panel. As you can see, it also features antenna in and out, S-video and more. July 2009  21 Tevion’s on screen display of a JPEG still image. Ignore the digital camera interference lines – this is seriously under-saturated. And this was the better of the two Tevions I tried – I’d taken the first one back already! also an option to select a frame of the program as a visual ID. Another nicety is that the Tevion can insert chapter markers into the program; these will be automatically spaced five, ten and fifteen minutes apart during the recording. By now you’re probably thinking this piece of hardware is a whizzer; well, not quite. The first warning should have sounded when I found the on-screen menu a bit washed out but the penny didn’t drop until I made a recording, and then replayed it. Show me the colour! Where’s all the colour, I cried out? It didn’t matter whether I tweaked the Tevion’s colour saturation/contrast/ brightness, adjusted the TV, darkened the room, pulled the curtains – the colour depth was just not there. Taking the disc to other DVD players (I’ve got three – don’t ask why!) revealed full-bodied colour. A phone call to Tevion tech support elicited the advice to swap the unit at ALDI for another. Which I did. Took it home, re-installed it. This was better; at least now I could read the menus more easily. But the replay was still noticeably desaturated. At this point I decided to run a colour chart past the Tevion, showing the primaries: red, green, blue as well as the complementary hues: cyan, magenta and yellow. It was apparent that the primaries were fine on the Tevion but the system was not delivering magenta (mix of 22  Silicon Chip Compare this off-screen shot of the same Manly ferry image, as displayed by the AWA DR711 recorder. Note how much more saturated the image is and as a result, how much more detail there is. Oh bliss, oh joy! blue and red) or yellow (mix of red and green), whereas the other players were delivering all primaries and complementaries. Not happy, Jan! AWA to the rescue By this time matters had become a little more complex as Big W announced the sale of their entry, a nicely satin-chromed model AWA DR711, with cosmetic differences but with a near-identical feature list and specs. Same factory in China? Possibly. Price? $148. Being a canny shopper I managed to snaffle one just two days before the price dropped to an on-sale special of $128! But the good news was that at last I could see the on-screen menu clearly and matters only got better as I viewed on-air broadcasts and then ran some tests. What a difference! Colours were now fully on while the brightness and contrast range were good. The AWA unit is identical in features and operating modes to the Tevion, while the remote control differs slightly. It is obviously the one to go for. I’m now very happy with my purchase and plan to retire the home VCRs for day-to-day recording. Disc is in. But you’re probably wondering why I bought a DVD recorder with an analog tuner instead of considering a more expensive unit with an inbuilt digital tuner. My attitude is that analog TV transmissions have some years to run before they cease to be broadcast and even after that, I will be able to couple A/V signals from my set-top box to the DVD recorder. In the meantime, I have the use of a DVD recorder at a bargain price. The Tevion screen display of an RGB/CMY chart. The primary colours appear OK on the Tevion but the system does not correctly deliver magenta (mix of blue and red) nor yellow (mix of red and green). It wasn’t an isolated dud: this is the better of the two Tevions I tried before giving up on them and going to AWA. siliconchip.com.au AWA DR711 Specifications Power Supply: .................. AC 100V-240V/50Hz-60Hz, 35W. Signal Modulation: ........... PAL/NTSC. Radium Laser: .................. Wavelength 650nm, 780nm. Frequency Response:........ DVD audio: 4Hz-22kHz (48kHz sample frequency).             4Hz-44kHz (96kHz sample frequency). ......................................... CD audio: 4Hz-20kHz. S/N: .................................. >90dB. Dynamic Range: ............... >90dB. Operating temperature: .... 0-40° C. Video out: ......................... 1.0V (P-P), S-Video out: ..................... (Y) 1.0V (P-P) 75; (C) 0.286V (P-P), 75 Audio output: ................... 2.0V (RMS maximum). Receiving Modulation: ..... PAL I, PAL D/K, PAL B/G, SECAM, L SECAM D/K SECAM B/G. Last Thoughts As we all know, the majority of consumer electronic products is manufactured in China, either under an international monicker like Sony, Panasonic etc or a truckload of generic labels, like Tevion, AWA and many others. With the major brands you can presume the companies keep a strict eye on the products before they reach the market. With generic brands, sold through retail outlets, one can only presume that a similar degree of surveillance is applied before the items are placed on shop shelves before sale. From my experience with these two ostensibly identical DVD recorders it would appear that, in the case of one retailer, this degree of quality control was not maintained. SC SMART PROCUREMENT SOLUTIONS Unit 3, 61-63 Steel Street Capalaba QLD 4157 AUSTRALIA Ph (07) 3390 3302 Fx (07) 3390 3329 sales<at>rmsparts.com.au www.rmsparts.com.au o Resistors o Capacitors o Potentiometers o Crystals o Semiconductors o Optoelectronics o Relays o Buzzers o Connectors o Switches o Hardware o Chemicals & Fluxes While cosmetically different to the Tevion, the AWA has similar specs and operating modes. The rear panel also reveals S- Video input as well as output along with optical audio (Toslink) and coaxial output. Apart from more versatile, it significantly out-performs the Tevion in the colour department. siliconchip.com.au WHOLESALERS  DISTRIBUTORS  KITTING SOLUTIONS     July 2009  23 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: dicksmith.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: dicksmith.com.au Mk.3 Lead-Acid Battery Zapper and Desulphator Here is a revised version of the popular Lead-Acid Battery Zapper featured in the May 2006 issue of SILICON CHIP. It is now separate from the Battery Condition Checker and much easier to build. At the same time it has been revamped for more reliable long-period operation with 6V, 12V & 24V batteries. By JIM ROWE T HE LEAD-ACID Battery Zapper & Condition Checker published in the May 2006 issue has been a very popular project but since it was published a few shortcomings have become apparent. The metering circuit on the Battery Condition Checker sometimes had a tendency to “lock up” on the 6V range and the current pulse Disclaimer! Not all batteries can be rejuvenated by zapping. They may be too heavily sulphated or may have an open-circuit cell connection. Nor can the zapper restore a battery which is worn out; ie, one in which the active material on the plates has been severely degraded. Depending on the battery, it is also possible that any rejuvenation effect may only be temporary. 26  Silicon Chip loading circuit was sometimes un­ stable with 24V batteries, if the power switching MOSFETs were at the high end of their transconductance range. In addition, the test current pulse amplitude was fixed at about 30A; OK for car batteries but too high for batteries used in motorbikes and for sealed lead acid (SLA) batteries. Many readers also found the combination of the Battery Zapper & Condition Checker fairly tricky to assemble and disassemble because it was a bit of a shoe-horn job into the plastic case. In view of this, we recently decided to develop improved versions of both the Checker and the Zapper but to feature them as separate projects, to make them easier to build and use. The revised Battery Condition Checker is planned for publication next month. What the Zapper does First of all, let’s have a quick recap about zapping and what it’s all about. Lead-acid batteries have been used to store electrical energy for over 170 years – ever since Gaston Plante built the first one back in 1834. But lead-acid batteries are not without their faults. Probably their main drawback is that they tend to have a relatively short working life, typically no more than about three years although with care, they can last much longer than that. So why such a short life? Well, every time energy is drawn from a leadacid battery, lead and sulphate ions from the electrolyte combine and are deposited on the plates in the form of soft lead-sulphate crystals. Then when the battery is recharged, these crystals dissolve again in the sulphuric acid electrolyte. At least MOST of them redissolve – but not all. Even if the battery is never over-discharged and always recharged promptly after it has been discharged, a small proportion of the lead sulphate crystals tend to remain on the plates, siliconchip.com.au where they harden into crystals of a much less soluble and less conductive “hard” lead sulphate. The formation of these hard lead sulphate crystals gradually reduces the energy storage capacity of the battery, both by masking the active areas on the plates and also by reducing the concentration of lead and sulphate ions in the electrolyte. This “sulphation” effect has been known about for many years. It’s also well known that the effect happens much faster if a battery is overdischarged, left in a discharged state for long periods, or frequently undercharged. Batteries mistreated in these ways tend to have a particularly short working life. For a long time, sulphation was regarded as non-reversible and batteries that had lost too much of their capacity from it were simply junked. This was not only wasteful but caused an environmental problem, because siliconchip.com.au LITTLE GEM DIGITAL MULTIMETER 37.25 v WOW WOW WOW WOW ZAPPER WOW V + + – – METER ZAPPING 20A DIGITAL MULTIMETER WOW WOW SILICON CHIP A WOW WOW WOW  WOW 2A COM +V – + LEAD-ACID BATTERY ZAPPER/DESULPHATOR + + FUSE 3A BATTERY FU SE – 24V BATTERY CHARGER 6V/12V ON ON + – + BATTERY CHARGER CHARGER – – MIGHTY QUICK BATTERY CHARGER 0 1 2 3 4 + – 5 BATTERY + – Fig.1: here’s how the Battery Zapper is connected to a battery and charger. The multimeter monitors the zapping pulses and should be set to a range of 100V DC or more. In addition, make sure that the Battery Voltage switch (S1) is set in the correct position for the battery you’re going to be zapping. July 2009  27 Parts List 1 ABS Jiffy box, UB2 size (197 x 113 x 83mm) 1 PC board, code 04107091, 185 x 100mm 3 SPDT mini toggle switches (S1S3) 2 speaker box binding posts, red (Jaycar PP-0434 or equivalent) 2 speaker box binding posts, black (Jaycar PP-0435 or equivalent) 1 Premium binding post, red (Jaycar PT-0460 or equivalent) 1 Premium binding post, black (Jaycar PT-0461) 1 M205 LV panel-mounting fuseholder 1 3A slow blow M205 fuse cartridge (F1) 2 6073B type TO-200 heatsinks (HS1, HS2) 1 8-pin DIL IC socket 1 220µH air-cored inductor (L1) both lead and sulphuric acid are highly toxic materials. Around the middle of last century though, farmers in rural areas discovered that they seemed to be able to resuscitate sulphated batteries and extend their life by zapping them with the high-voltage pulses from their electric fence controllers. They didn’t quite know how this method worked but kept using it simply because it did. Then in 1976, the US Patent Office granted a patent to William H. Clark of Salt Lake City, Utah, for a method 2 1mH air-cored inductors (L2, L3) 3 Nylon cable ties, 250-300mm 4 M3 x 25mm tapped spacers 6 M3 x 6mm machine screws, pan head 4 M3 x 6mm machine screws, countersunk head 8 M3 flat washers 2 M3 hex nuts 1 400mm length 1mm tinned copper wire 1 300mm length 0.7mm tinned copper wire Semiconductors 1 555 timer (IC1) 1 BC327 PNP transistor (Q1) 1 IRF540N MOSFET (Q2) 2 6.8V 1W zener diodes (ZD1,ZD2) 1 30V 1W zener diode (ZD3) 1 27V 1W zener diode (ZD4) 1 5mm red LED (LED1) of charging lead-acid batteries by means of narrow high current pulses – claimed to dissolve the lead sulphate crystals and hence prolong battery life. Since then, a number of designs for pulse-type battery rejuvenators or “zappers” have appeared in electronics magazines around the world. We should point out that there is still argument and controversy about whether or not the sulphation of flooded lead-acid batteries can be reversed. That in turn means there is still argument about the effectiveness +12V + K L2 1mH – A SWITCH (Q2) 28  Silicon Chip + – 470 F Fig.2(a): during the first phase of the circuit’s operation, current flows from the battery (and/or battery charger) and charges a 470mF electrolytic capacitor via 1mH inductor L2. of zapper-type pulse rejuvenators. However, many people have reported achieving a useful amount of rejuvenation on badly sulphated batteries, using zappers – including our earlier designs. That’s why we’re describing this new version. At the same time, we should also point out that this zapping process does not appear to work with sealed lead acid (SLA) batteries with a “gel” electrolyte. So we don’t recommend building the Battery Zapper to try rejuvenating this type of battery. L2 1mH K L1 220 H A CAPACITOR CHARGING PHASE Resistors (0.25W, 1%) 1 1MΩ 1 470Ω 5W wirewound 1 270kΩ 1 150Ω 1 27kΩ 1 100Ω 1 15kΩ 1 15Ω 5W wirewound 1 6.8kΩ I pulse (D3) A Capacitors 1 470µF 63V low ESR RB electrolytic 1 470µF 16V low ESR RB electrolytic 1 470nF 100V MKT polyester 1 100nF 100V MKT polyester 1 22nF 100V MKT polyester 3 10nF 100V MKT polyester 1 4.7nF 100V MKT polyester +12V FROM BATTERY AND/OR CHARGER I charge (D3) 2 1N4148 diodes (D1,D2) 1 BY229-200 fast recovery diode (D3) 2 UF4003 ultra-fast diodes (D4,D5) SWITCH (Q2) B L2 1mH K 12V (D3) L1 220 H I transfer A – + 470 F ENERGY TRANSFER PHASE Fig.2(b): next, switch Q2 is closed for 50ms, and current flows from the capacitor into L1. As a result, the energy stored in the capacitor is transferred to the inductor’s magnetic field. L1 220 H 470 F SWITCH (Q2) C DISCHARGE/PULSE GENERATION PHASE Fig.2(c): finally, switch Q2 opens again, interrupting the inductor current and causing a high-voltage pulse across the inductor with the polarity shown. The green arrow shows the discharge current path. siliconchip.com.au 24V BATTERY S1 VOLTS 6/12V 100 K 470 F 16V LOW ESR 100nF 27k K A A BATTERY 470  5W A ZD1 6.8V 1W LED1 ZD2 6.8V 1W K L2 1mH AIR K D3 BY229-200 A 7 6 D1 K 8 4 6.8k 3 IC1 555 A A Q2 IRF540N 4.7nF E B C K D G A S Q1 BC327 CHARGE ON/OFF S3 CHARGER + 10nF 100V D5 UF4003 A 150 15  5W D4 UF4003 K 1 10nF L3 1mH AIR L1 220 H AIR 5 2 22nF 100V K D2 BATTERY + 10nF 100V  A 270k S2 F1 3A K 15k A ZD3 30V 1W ZD4 27V 1W METER + K 470 F 63V LOW ESR 470nF 100V 1M METER – CHARGER – BATTERY – D1, D2: 1N4148 A K D4,D5: UF4003 A SC  2009 K ZD1–ZD4 A K K A BY229-200 BC327 LED IRF540N K D B E C K LEAD-ACID BATTERY ZAPPER MK3 G A D S Fig.3: the circuit uses 555 timer IC1 to turn MOSFET Q2 on for 50µs every 1ms (ie, at a 1kHz rate). Transistor Q1 turns on and shorts Q2’s gate to ground each time IC1’s pin 3 output switches low to ensure a fast turn off, while zener diodes ZD3 and ZD4 form an over-voltage protection circuit for Q2, which has a maximum voltage rating of 100V. It’s also worth noting that even on flooded lead-acid batteries, pulse desulphation is not quick. It can involve tens or even hundreds of hours to achieve a significant amount of rejuvenation. How it works As with our earlier units, the new Battery Zapper converts some of the energy from the battery itself (usually aided by a battery charger) into narrow high-voltage pulses which are fed back to the battery. This is done using the basic circuit configuration shown in Fig.2, which also shows its three operating phases. In the first phase (A), current flows from the battery and/or charger through 1mH inductor L2 and charges a 470µF capacitor connected between the inductor’s lower end and earth (battery negative). This phase lasts for about 950µs – long enough for the capacitor to charge up to the battery voltage. siliconchip.com.au At the end of this charging phase, switch Q2 (a power MOSFET) is closed for about 50µs (B), shorting the lower end of 220µH inductor L1 to ground and effectively connecting it right across the charged 470µF capacitor. As a result most of the energy stored in the capacitor is transferred into the inductor’s magnetic field. Hence this second phase is known as the energy transfer phase. The third phase (C) begins when switch Q2 is opened again. This breaks the inductor’s transfer current, which causes a high voltage back-EMF pulse to be generated across L1 with the polarity shown. Fast recovery diode D3 then feeds this high voltage pulse back to the battery, as shown in Fig.1(c). The third phase is therefore known as the discharge/pulse generation phase. Circuit details Refer now to Fig.3 for the full circuit details of our new Lead Acid Battery Zapper. You should now be able to identify this basic pulse generation circuit in the centre of the diagram. The discharging switch Q2 is now shown in its true form as an IRF540N power MOSFET, which we’re using here as a fast electronic switch. Virtually all of the circuitry to the left of Q2 is used to switch it on and off repeatedly, so that the pulse generating circuit produces a stream of zapping pulses. The pulses used to switch Q2 on and off are generated by IC1, a 555 timer. This is configured as an astable oscillator running at about 1kHz but with an output consisting of narrow positive pulses about 50µs wide, with spaces of about 950µs between them (ie, a 1:19 mark-space ratio). Each of these narrow pulses is used to turn on Q2, with diode D2 and transistor Q1 used to ensure that Q2 is switched both on and off as rapidly as possible. So Q2 is turned on for 50µs, then off for 950µs and so on. The 150Ω resistor in series with Q2’s gate is included to July 2009  29 UF4003 6.8k F S K BT229-200 D4 L2 1mH A D3 + ZAPPING LED1 METER- CABLE TIE 15k Q1 BC327 63V 22nF +B 9002 © FU SE 3A CHARGER BATTERY S2 S1 10nF BAT VOLTS 10nF 470  5W DI CA-DAEL YRETTA B 3K M REPPA Z 19070141 BATTERY- F1 BATTERY+ CABLE TIE 470 F S3 +C L3 1mH 15  5W S CHARGER+ 100 METER+ 1M 150 D2 4148 F S 470nF 10nF 4.7nF 27k 4148 270k ZD1 ZD2 D5 +M L1 220 H D1 470 F 27V UF4003 IC1 555 6V8 ZD4 30V Q2 IRF540N 100nF 6V8 ZD3 CHARGER- CABLE TIE F Fig.4: follow this parts layout diagram to assemble the PC board and make sure that all polarised parts are orientated as shown. The large inductors (L1-L3) are secured to the board using plastic cable ties which pass through holes on either side. suppress any tendency for it to oscillate during the switching transitions. That’s all there is in the basic zapping circuit. Now let’s look at the refinements. Zener diodes ZD1 and ZD2 are included to prevent the supply voltage for IC1 from rising above 13.6V, espe30  Silicon Chip cially when the Battery Zapper is being used with a 24V battery. They do not conduct any significant current when 6V batteries are being zapped and for 12V batteries they only serve as a limiter for any zapping pulses which find their way back from the cathode of D3, via the 100Ω series resistor. Note that switch S1 inserts a 470Ω 5W resistor in series with the 100Ω resistor when the unit is being used with a 24V battery, to limit the dissipation in ZD1 and ZD2. Zener diodes ZD3 and ZD4 form an over-voltage protection circuit for Q2, which has a maximum voltage rating of 100V. These zener diodes limit the maximum pulse voltage to about 70V under all conditions. Pulse level monitoring D5 is an ultra-fast diode which forms part of a simple half-wave rectifier circuit with the 1MΩ resistor and 470nF reservoir capacitor. These provide a DC voltage proportional to the maximum pulse amplitude between the “Meter” terminals, to allow monitoring the pulse level with a standard (high-impedance) digital multimeter. LED1 indicates when the Battery Zapper is generating pulses and also gives a rough idea of their amplitude. Because the pulses are quite narrow, diode D4 is used to charge the 22nF capacitor to their full voltage (less the battery voltage across the 470µF capacitor) and the LED is able to draw a steady current from the capacitor via the 6.8kΩ resistor. This allows LED1 to glow fairly brightly, without taking too much of the energy in the zapping pulses. Fuse F1 is provided mainly to protect inductors L2 and L1 against damage in the event of Q2 developing a short circuit or being switched on continuously due to a fault in IC1 and its associated components. The circuitry at upper right is to allow safe connection and disconnection of the unit to a battery (via switch S2) and also to allow safe connection or disconnection of a standard battery charger to the battery at any time, via switch S3. Inductor L3 acts as a choke for the zapping pulses, preventing the charger from absorbing them and possibly being damaged, while the 10nF capacitors across both S2 and S3 are spark suppressors. The 15Ω 5W resistor between L3 and S3 is there to limit the current that can be drawn from the charger, preventing damage should the battery develop a short circuit during zapping. Construction To make the new Battery Zapper as easy as possible to build, virtually all the components are mounted on a PC siliconchip.com.au This view shows the fully assembled PC board. Note that the three toggle switches would not normally be mounted on the board at this stage but are instead fitted with extension leads and mounted on the lid of the case – see text. Warning! (1) This circuit generates highvoltage pulses which could easily damage the electronics in a vehicle. Do not connect it to a car battery installed in a vehicle. (2) Hydrogen gas (which is explosive) is generated by lead-acid batteries during charging. For this reason, be sure to always charge batteries in a well-ventilated area. board coded 14107091 and measuring 185 x 100mm. This PC board has rounded cut-outs in each corner so it will fit snugly inside a standard UB2size ABS utility (Jiffy) box. The only components which don’t mount directly on the PC board are switches S1-S3, the fuseholder for fuse F1 and the various input terminals. All of these off-board components mount on the box lid (which becomes (3) Never connect high-current loads directly to a battery’s terminals. This can lead to arcing at the terminals and could even cause the battery to explode! Note too that the electrolyte inside lead-acid batteries is corrosive, so wearing safety glasses is always a good idea. the front panel) and are connected to the board beneath via short lengths of tinned copper wire, as you can see from the parts layout diagram of Fig.4 and the cross-section diagram of Fig.6. Begin assembly of the PC board by fitting the wire links. There are only two of these and they’re both only 10mm long (horizontal section), so they are easily made from resistor lead off-cuts. After the links, fit the (4) This unit is not suitable for use with SLA batteries. Table 1: Resistor Colour Codes o o o o o o o o o o siliconchip.com.au No.   1   1   1   1   1   1   1   1   1 Value 1MΩ 270kΩ 27kΩ 15kΩ 6.8kΩ 470Ω 5W 150Ω 100Ω 15Ω 5W 4-Band Code (1%) brown black green brown red violet yellow brown red violet orange brown brown green orange brown blue grey red brown not applicable brown green brown brown brown black brown brown not applicable 5-Band Code (1%) brown black black yellow brown red violet black orange brown red violet black red brown brown green black red brown blue grey black brown brown not applicable brown green black black brown brown black black black brown not applicable July 2009  31 36 A 36 A C 41 19 C B 45 5 37 56 D 19 E D 23 F F F 40.5 20 20 D 57 28 D 10 A 10 36 A 36 HOLES A: 3.5mm DIAMETER, CSK HOLE B: 5.0mm DIAMETER HOLES C: 10.0mm DIAMETER CL HOLES D: 6.0mm DIAMETER HOLE E: 13.0mm DIAMETER HOLES F: 6.5mm DIAMETER ALL DIMENSIONS IN MILLIMETRES Fig.5: the drilling template for the front panel (ie, the lid of the case). Drill small pilot holes first & use a tapered reamer to make the larger holes. 8-pin socket for IC1, making sure you orientate it with the notch end to the left so it will guide you later when plugging in IC1. 32  Silicon Chip Next, fit the smaller resistors, then fit the two larger 5W resistors which are in ceramic block packages. It’s a good idea to fit these about 1mm above the board rather than flat down on it. This will provide them with a small amount of ventilation and also protect the board from damage if they should become overheated. Follow these parts with the capacitors, starting with the smaller nonpolarised MKT parts and then moving to the electrolytics. There are only two of the latter but be sure to fit them in the correct places and with the correct orientation, otherwise you’ll strike trouble later. Now you can fit the semiconductor parts, starting with diodes D1, D2, D4 & D5 and then zener diodes ZD1-ZD4 and transistor Q1. Once they’re in, fit diode D3 and power MOSFET Q2. These are both in TO-220 packages and are mounted flat on the top of the PC board along with small 6073B-type heatsinks. In both cases, their leads must be bent down by 90° about 6mm away from the bodies, so they’ll pass down through the matching holes in the PC board. The tabs of both devices are then secured down against the heatsink using an M3 x 6mm machine screw and M3 nut. Then when the screws are nuts are tightened, the board is upended and the device leads soldered to the pads underneath. Don’t solder the leads before bolting them down, otherwise you could crack the copper tracks as the screws are tightened. Once D3 and Q2 are in place you can fit LED1. This mounts vertically in the upper centre of the board, with its leads straight and with the underside of its body spaced about 24mm above the board so that it will later just protrude through its matching hole in the front panel. With LED1 in place, now is the time to fit the largest components which mount on the board: the three aircored inductors. During this process, it’s important to dress each inductor’s leads carefully so they’re straight and at 90° to the side cheeks of the inductor bobbin. This will allow the leads to be fed through their matching board holes without strain as each inductor is lowered into position. Be sure to orientate each inductor so that its “start” lead (near the centre of the bobbin) passes through the matching “S” hole on the board, while its “finish” lead (on the outside) passes through the hole marked “F”. When each inductor is sitting flat down against the top of the board, siliconchip.com.au CHARGER NEGATIVE TERMINAL M205 BOX LID/ FUSEHOLDER FRONT PANEL CHARGER POSITIVE TERMINAL BATTERY POSITIVE TERMINAL S1,S2,S3 S1 L3 1mH/20AWG 470  5W 15  5W PC BOARD MOUNTED BEHIND PANEL VIA FOUR M3 x 25mm TAPPED SPACERS WITH 2x FLAT WASHERS UNDER EACH ONE CABLE TIE SECURING L3 TO PC BOARD PC BOARD NOTE: BATTERY NEGATIVE TERMINAL OMITTED FOR CLARITY Fig.6: this end-elevation diagram shows how the PC board is mounted on the back of the lid on M3 x 25mm tapped spacers & washers. The front panel parts are connected to the PC board via “extension” wires. Left: the charger, battery & meter terminals are all mounted on the lid of the case, along with the fuse and toggle switches (not shown here), before the PC board is attached. XYBER Data Recovery Data recovery for the rest of us: reliable, affordable, thorough, fast, professional. MacOS•Windows•Novell•Linux•Servers Disk•Flash•Optical•MO•RAID•NAS•SAN Data•Photo•Audio•Video•Forensics Wholly Australian and proud of it :-) www.xyber.com.au Xyber. At your service. Since 1985. 1800 88 31 77 into its socket, taking care to fit it with the correct orientation. The board assembly can then be placed aside while you prepare the box lid/front panel. Drilling the front panel you can solder its leads to the pads underneath and trim off any excess. A 250mm-long Nylon cable tie is then used to hold the inductor in place. As shown, this tie passes down through one of the edge holes provided in the board and up through the other. siliconchip.com.au Tighten the ties quite firmly to secure each inductor in place. Finally, cut off the excess ends of the cable ties, leaving only about 4mm. Once all three inductors have been fitted to the board, it is almost complete. All that remains is to plug IC1 Preparing the front panel requires 15 holes to be drilled and reamed. Their sizes and positions are shown in Fig.5, which is also shown actual size so you can use a photocopy as a drilling template if you wish. After all of the holes have been drilled and de-burred, you may want to fit the lid/panel with a stick-on escutcheon to give it a more professional finish. To make this step easier, we have produced an artwork for the front panel – see Fig.7. The easiest way to make a front panel is to photocopy the artwork onto an adhesive-backed A4 label sheet, over which is then applied a sheet of protective clear self-adhesive film (like “Contact” or “Duraseal”). Then the artwork can be cut to size and its backing sheet peeled off, allowing it to be placed carefully on the top of the box lid. Another option is to download the July 2009  33 artwork from the SILICON CHIP website and print it out. Once the label is in place you can then cut out the various holes in the escutcheon using a sharp hobby knife, guided by the holes already drilled in the lid. Fuseholder & switches The next stage is fitting the fuseholder, toggle switches and binding posts to the front panel. Don’t use excessive force to tighten the nut on the fuseholder, as you might strip the plastic thread. The three toggle switches are identical, so they can go in any of the three positions. After these fit the red and black plastic binding posts, which are used for the “Meter” terminals. The other two pairs of binding posts are gold-plated speaker terminals and they probably seem too good for this application. However, they have the advantage that they are readily available and will take heavier cables. They also have a top section which can be unscrewed completely to allow connections via crocodile clips. The binding posts with the red mounting 34  Silicon Chip The views above left & top show how the assembly goes together, while at right is the completed Battery Zapper. Make sure that all the extension wires fitted to the front-panel items go through their corresponding holes in the PC board. bushes are used for the two positive terminals. Extension wires Once all of these items have been fitted to the front panel, it can be turned over and their connection lugs or spigots fitted with “extension” wires made from short lengths of tinned copper wire. This is necessary to extend the leads down through the matching holes in the PC board when the latter is mounted up behind the panel. The extension wires for S1, S2 and S3 need only be about 25mm long but with one end bent into a tiny hook so that it can be attached firmly to the switch lug before soldering. The wires used for the fuseholder extensions should be about 15mm and 30mm long respectively, with the longer wire used for the holder’s side connection. As before, these wires should both be attached to the fuseholder lugs by forming them into a small hook before soldering. The extension wires used for the binding posts should be cut from siliconchip.com.au LEAD-ACID BATTERY ZAPPER and DESULPHATOR + METER – longer lengths of 1mm diameter tinned copper wire – about 60mm long. The centre of each wire is then wound tightly once around the notch near the lower end of each binding post’s spigot, before soldering. The two ends are then bent down along the axis of the post and finally twisted together to form a stout extension wire to pass down through the board. All of these extension wire details are shown clearly in the diagram of Fig.6. When all of these extension wires have been fitted the next step is to attach the PC board to the panel. This is done by first mounting an M3 x 25mm tapped spacer to the rear of the panel near each corner, with M3 x 6mm countersink head screws passing down through matching holes ‘A’ in Fig.5. Tighten these screws firmly to ensure that they don’t work loose later. Now offer up the PC board assembly underneath the panel, making sure both that the various extension wires pass through their matching holes in the board and that LED1 also passes up through its matching hole in the panel. Then once the board has moved up to almost touch the spacers (it won’t quite reach them because of the cable ties around the inductors), up-end everything to allow you to fit two M3 flat washers between the board and each spacer. Secure the assembly using M3 x 6mm machine screws (pan head). Finally, solder the ends of all of the extension wires to the copper pads on the board and clip off any excess wire. It might all sound complicated but it’s easier to do than to describe in words. Fig.6 shows the details. Your new Battery Zapper should now be fully wired up and you should be able to lower the complete front panel/PC board assembly down onto the box. The assembly can then be fassiliconchip.com.au ZAPPING + FUSE 3A BATTERY – 24V BATTERY CHARGER 6V/12V ON ON + CHARGER SILICON CHIP .com.au – Fig.7: this full-size front-panel artwork can be photocopied and used direct or you can download a PDF of the artwork from the SILICON CHIP website and print it out on a colour printer – see text. tened to the box using the self-tapping screws provided. Don’t forget to fit the small plastic bungs over each screw recess, to finish the job. Putting it to use It’s very easy to connect the Battery Zapper Mk.3 to a battery, charger and optional DMM – just follow the connection diagram of Fig.1. Before you start, make sure that the Battery Voltage switch (S1) is set in the correct position for the battery you’re going to be zapping. Switches S2 and S3 should both be in their upper “Off” positions. The other main thing to watch is that July 2009  35 Fig.8: this scope shot shows the unit working with a 12V battery. The yellow trace is the voltage waveform seen at the drain of MOSFET Q2, while the green trace shows the resulting spike waveform impressed across the battery itself. The blue trace shows the resulting ripple voltage across the 470µF capacitor. Fig.9: this scope shot shows the Battery Zapper working with a 24V battery. The yellow trace at top is the voltage waveform seen at the drain of MOSFET Q2 and is shown at 70V peak-peak. The spike waveform impressed across the battery (green trace) is 56V peak-to-peak, indicating a battery in need of zapping. the unit’s battery and charger terminals are connected to the battery and the charger respectively with the correct polarity, ie, positive-to-positive and 36  Silicon Chip negative-to-negative. If you connect the battery with incorrect polarity, you will blow the 3A fuse and the chances are that you will blow the MOSFET (Q2) as well. There, you have been warned! If you are using a DMM to monitor the zapping pulses, it is connected to the Battery Zapper’s meter jacks as shown. The DMM should be set for a DC voltage range of 0-100V or more. To begin zapping a battery which has a reasonable charge, all you do is switch S2 to its lower ON position. Zapping LED1 should begin to glow, showing that the high-voltage zapping pulses are being generated and applied to the battery. If you have a DMM connected, it should be giving a reading of more than the battery’s nominal voltage – up to about 70V DC, depending on the amount of sulphating in the battery. If you are in a quiet location, you may also hear a faint 1kHz whistle from the inductors – further evidence that the circuit is working. If Zapping LED1 doesn’t light and the DMM simply reads the battery’s nominal voltage (or less), this means that the battery doesn’t have enough charge at present even to operate the Zapper. In that case, apply power to the charger and turn on the Zapper’s charger switch S3, to allow the charger to provide enough current to support the zapping process. Zapping should then begin, unless the battery is beyond redemption. As the zapping progresses, LED1 will tend to glow less brightly, as the lead sulphate crystals in the battery are gradually dissolved and the amplitude of the zapping pulses slowly drops. But be aware that this may take a considerable time. At the same time the reading on the DMM should slowly drop as well, eventually returning to the battery’s normal “under charge” terminal voltage. By the way if you do need to use a battery charger to allow the zapping process to proceed, the 15Ω resistor inside the Battery Zapper will limit the charging current to less than 1A, mainly to prevent the battery from being damaged by over-charging if zapping needs to continue over several days. This means that after the zapping process has been completed, the battery may still need further charging. Note that, depending on the charge in the battery, the Battery Zapper circuit will draw up to 300mA. This means that you must connect a battery charger, otherwise the battery will end SC up fully discharged. siliconchip.com.au SILICON SILIC CHIP siliconchip.com.au YOUR DETAILS NEW! 6 MONTH SUBS AND AUTO RENEWAL NOW AVAILABLE Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 PO BOX 139, COLLAROY NSW 2097 email: silicon<at>siliconchip.com.au Phone (02) 9939 3295 Fax (02) 9939 2648 This form may be photocopied without infringing copyright. 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PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with your credit card details OR MAIL This form to PO Box 139 Collaroy NSW 2097 July 2009  37 07/09 Ideal for finding steel frames and studs, steel bracing and nails in plaster walls, this Metal Locator can also show the length of the tang in knife handles, screwdrivers and other tools. As well, it can discriminate between ferrous and non-ferrous metals. By JOHN CLARKE Metal Locator I F YOU WANT TO hang pictures, shelving or mirrors on a plaster wall in a steel-framed building it is useful to find where the metal studs are. You may wish to secure your screws to the stud or alternatively, you may wish to avoid the stud and attach directly to the plaster wall using suitable fasteners. There are also other hidden items within the wall that should be located before drilling, such as metal bracing straps, screws and nails. With the Metal Locator you can 38  Silicon Chip find the metal stud positions as well as any steel bracing, screw heads and nails. That is, provided the metal is no deeper than 25mm inside the wall. For small nails in wooden studs, the Metal Locator can detect them provided that the heads are within 10mm of the wall Specifications Detection range: up to 25mm from the underside of the case Current drain: <20mA with LED fully lit surface. Naturally, this device does not locate the timber studs themselves, nor can it find steel frames in walls that have a cladding thicker than 25mm (a very unusual wall, especially inside!). Nor can it detect power cables inside walls. The Metal Locator can also distinguish between ferrous and non-ferrous metals. Ferrous metals include mild steel, stainless steel (both magnetic and non-magnetic), wrought iron, high tensile steel, galvanised iron, tin plated siliconchip.com.au as voltage changes that can easily be amplified before driving the LED. The LED brightness varies with a change in frequency from the oscillator. An offset adjustment using VR1 allows the LED brightness to be set at a very low level to brighten with non-ferrous metals. The LED can be set at a higher level to detect ferrous metals where the LED begins to dim. The buffer stage (IC2b) between the offset control and the amplifier is there to ensure there is no gain change with adjustment of VR1. BUFFER (IC2b) OFFSET ADJUST VR1 AMPLIFIER (IC2a) FREQUENCY TO VOLTAGE CONVERTER OSCILLATOR (IC1) LED & DRIVER (LED1, Q1) (C1,C2,D1,D2,VR2) DETECTOR COIL (L1) Fig.1: the block diagram has the same functionality as the circuit below. steel (steel cans or tinplate), passivated steels and cast iron. Non-ferrous metals include copper, brass, zinc, aluminium, gold, silver, lead and tin. In the presence of ferrous metals, the LED on the Metal Locator dims. Conversely, the LED brightens in the presence of non-ferrous metal. For ferrous metals, the sensitivity knob is adjusted so that the LED is reasonably bright in the absence of the metal. The LED then dims in the presence of ferrous metal. To detect non-ferrous metals, the sensitivity is adjusted so that the LED is dim in the absence of the metal. The LED will then brighten in the presence of the non-ferrous metal. Greater sensitivity can be had with the LED just glowing in the absence of metal for detection of either metal type. The Metal Locator is housed in a compact plastic case that includes a 9V battery compartment. On the lid are the on/off switch, sensitivity control and the indicating LED. Circuit details The circuit in Fig.2 is based on just two ICs. One is a CMOS version of the 555 timer (IC1) and the other is a general-purpose LM358 dual op amp (IC2a and IC2b). IC1 operates as an unconventional astable oscillator. To explain how it works, we will compare it to a conventional 555 astable oscillator, as shown in Fig.3. This has resistor R1 between its output at pin 3 and both the trigger and threshold inputs at pins 2 and 6. Capacitor Cx is connected between pins 2 & 6 and ground. Initially, when power is first applied, the capacitor is discharged and the trigger input at pin 2 is at 0V. At this stage How it works Fig.1 shows the block diagram of the Metal Locator. It is based on an astable oscillator controlled by the detector coil, L1. The oscillation frequency changes with the presence of metal. For ferrous metals, the frequency decreases while for non-ferrous metals the frequency increases. The oscillator’s output is fed to a frequency to voltage converter. Small frequency changes are then detected REG1 78L05 +5V OUT 180k 10 F VR1 ADJUST 1k OFFSET LIN 10 F 10 K 7 IC2b D3 1N4004 A  LED1 180k 100nF 100 F 16V 8 5 6 IN GND S1 POWER ON IC2: LM358 BUFFER A K 1k 8 4 IC1 7555 C1 3 6 C1,C2 CHARGE D2 10nF L1 A C1 DISCHARGE 2 1 R1 470 OSCILLATOR 2 C2 DISCHARGE 3 K K C2 100nF D1 VR2 10k A C Q1 BC337 9V BATTERY E TP1 470 TPG FREQUENCY-TO-VOLTAGE CONVERTER METAL LOCATOR B 470k AMPLIFIER IC1, IC2 LED DRIVER 4 8 1 D1,D2: 1N4148 A SC 1 4 INDUCTOR L1: 400 TURNS OF 0.25mm ENAMELLED COPPER WIRE ON 20.5mm OD BOBBIN 2009 IC2a A K BC337 LED K D3: 1N4004 K A 78L05 GND B E C IN OUT Fig.2: the Metal Locator circuit is based on two low-cost ICs and a handful of other cheap components. siliconchip.com.au July 2009  39 +5V 8 4 OUT 3 7555 TRIG 2 THRESH R1 6 1 SQUARE WAVE OUTPUT Cx Fig.3: here’s a “traditional” 555 oscillator circuit with the frequency determined by R1 and CX. But as you can see in Fig.2, it’s possible to substitute an inductor and resistor to make it oscillate. the timer is triggered and the output at pin 3 goes high to equal the positive supply rail voltage. The capacitor now charges via R1. When the capacitor charges to the pin 6 threshold voltage (2/3 supply), the pin 3 output goes low (to 0V) and the capacitor now discharges via R1. When the capacitor voltage discharges to the trigger level voltage at pin 2 at 1/3 the supply, the pin 3 output goes high again to recharge the Cx capacitor. The process continues and so pin 3 produces a square wave output with the frequency determined by R1 and Cx. In the circuit of Fig.2, we substitute inductor L1 for R1 and R1 (470Ω) for capacitor Cx. It now operates as follows. At the instant of power being applied, inductor L1 is effectively a And here’s the proof! The top trace is the waveform at pin 3 while the green trace shows the waveform at pin 6. The waveform at pin 6 is the voltage across R1 and this shows that the current through R1 does not reverse; it merely varies between about 3.5mA and 7mA. Note the spikes generated each time the 555 changes state. high impedance and resistor R1 pulls the pin 2 input below the 1/3 supply threshold to trigger the pin 3 output to go high. Current then begins to flow through L1 and R1. As the current rises, the voltage across R1 increases until it reaches the 2/3 supply voltage threshold. This changes the state of the oscillator so that pin 3 goes low. The current through L1 does not change direction but ramps down until the voltage across R1 drops below the 1/3 supply threshold to retrigger the timer and pin 3 goes high again. The frequency is dependent upon the inductance of L1 and the resistance of R1 (which is fixed at 470Ω). L1 is an air-cored coil of wire. If metal comes close to this coil its inductance will Why Not Use A Stud Finder? Most readers know that stud finders are cheaply available from hardware outlets such as Bunnings and even from bargain stores. They often have three functions: stud, nail and power. While they are cheap and readily available, they can give misleading results when looking for screws or metal studs in walls. Nor can they discriminate between ferrous and non-ferrous metals and their sensitivity cannot be adjusted. 40  Silicon Chip change and this will alter the frequency of oscillation. For ferrous metals the inductance will increase and the frequency of oscillation will fall. For non-ferrous metal, the inductance will decrease and the oscillation frequency will increase. The frequency is around 94kHz and changes by up to 2kHz with metal near the coil. The output from IC1 is fed to a diode pump comprising capacitors C1 & C2, resistor VR2 and diodes D1 & D2. It functions as a frequency-to-voltage converter by dint of the size of C1 which is fairly small at only 10nF. This means that the DC voltage developed across C2 will vary as the frequency varies; it will be higher as the frequency increases and this allows the circuit to discriminate between ferrous and non-ferrous metals as the apparent inductance of L1 is changed. The DC voltage across C2 is amplified by op amp IC2a. This has a gain of about 470 (471 to be precise), set by the 1kΩ and 470kΩ feedback resistors. IC2a is buffered by transistor Q1 to provide a higher current drive for LED1. Offset control Op amp IC2a has an offset adjustment to enable adjustment of the LED brightness. In effect, the operating point of IC2a can be shifted up or down by varying the voltage applied to its inverting input. The varying voltage comes from IC2b, a unity-gain buffer which is fed by the wiper of the 1kΩ potentiometer VR1. Combined with the 180kΩ divider resistors, the range amounts to about 14mV. The buffer stage of IC2b ensures the gain of IC2a is kept at 471 and is not siliconchip.com.au D2 D1 C2 C1 10nF 100nF TPG S1 4148 LATE M R OTA C OL 9V BATTERY CABLE TIE 100F 4148 REG1 F 470 VR2 10k CON1 10  IC1 7555 PICAXE 4004 – TP1 100nF D3 ++ R1 with 180k LED1 A JOIN THE TECHNOLOGY AGE NOW - L1 180k VR1 1k LIN Q1 K 10F 10 470k 1k 470 04207091 IC2 LM358 10 F 100 F 10 F Fig.4 (top) shows the component layout for the Metal Locator, with the same-size photo prior to mounting in the case at left. Note the electrolytic capacitors need to be mounted folded over so they are flat on the PC board. affected by the resistance at the wiper of VR1. Any voltage change in VR1 is amplified in IC2a by 471, so the 14mV variation allows the IC2a output to be shifted over its full output range, from very close to 0V up to about 3.5V. This adjustment allows the LED to be set at the required brightness for metal detection. In effect, VR1 operates as a sensitivity control for the circuit. Trimpot VR2 provides a further range of adjustment. For optimum operation of VR1, VR2 is adjusted so the Developed as a teaching tool, the PICAXE is a low-cost “brain” for almost any project voltage at TP1 is at about half supply or +2.5V. This matches the nominal 2.5V available from the wiper of VR1 at its centre position. The circuit is powered from 5V, derived from a 9V battery and a 5V regulator (REG1). Diode D3 prevents damage to the 100µF capacitor and the 5V regulator if the battery is connected the wrong way around. The 5V supply is decoupled with a 10µF capacitor at REG1’s output and another 10µF capacitor at the supply rails for IC2. IC1 Easy to use and understand, professionals & hobbyists can be productive within minutes. Free software development system and low-cost in-circuit programming. Variety of hardware, project boards and kits to suit your application. Digital, analog, RS232, 1-Wire™, SPI, and I2C. PC connectivity. Applications include: Datalogging Robotics Measurement & instruments Motor & lighting control Farming & agriculture Internet server Wireless links Colour sensing Fun games How Safe Is That Kitchen Knife? The handles on some kitchen knives are unsafe because they have a very short tang. The Metal Locator can show just how long the metal tang goes into the handle of a kitchen knife or screwdriver. Many professional knives have the tang extending the whole length of the handles and this tang can be seen running in between the two handle sections that are riveted to the outside of the tang. But some low cost knives only have a tang that enters part way into a plastic moulded handle. They can even have imitation rivets along the handle length to give the impression that the tang runs along the whole handle length. A short tang means that a large amount of stress is applied to the handle when using the knife and it is liable to break. This can be dangerous, especially when doing heavy work such as cutting up pumpkins. Make sure you use a knife that is safe for the job. siliconchip.com.au Distributed in Australia by Microzed Computers Pty Limited Phone 1300 735 420 Fax 1300 735 421 www.microzed.com.au July 2009  41 Parts List – Metal Locator 1 PC board, code 04207091, 78 x 64mm 1 remote control case 135 x 70 x 24mm (Jaycar HB 5610 or equivalent) 1 front panel label 50 x 115mm 1 9V battery 1 9V battery snap 1 DPDT PC mount slider switch (Jaycar SS-0823 or equivalent; S1) 1 coil bobbin 20.5mm OD x 13mm ID x 10.5mm high 1 13m length of 0.25mm enamelled copper wire 1 knob to suit potentiometer 1 2-way screw terminals with 5.08mm pin spacing 4 T0-220 insulating bushes (used as spacers) 4 M3 x 4mm screws 1 20mm diameter x 12mm heatshrink tubing 1 100mm cable tie 9 PC stakes Semiconductors 1 7555, LMC555CN CMOS timer (IC1) 1 LM358 dual op amp (IC2) 1 78L05 three terminal 5V low-power regulator (REG1) 1 BC337 NPN transistor (Q1) 1 1N4004 1A diode (D1) 2 1N4148 signal diodes (D2,D3) 1 3mm high brightness red LED (LED1) Capacitors 1 100µF 16V PC electrolytic 2 10µF 16V PC electrolytic 2 100nF MKT polyester 1 10nF MKT polyester Resistors (1% 0.25W) 1 470kΩ 2 180kΩ 1 1kΩ 2 470Ω 1 10Ω 1 1kΩ linear 16mm potentiometer (VR1) 1 10kΩ 25-turn top-adjust trimpot (3296W type) (Code 103) (VR2) Here’s the completed PC board screwed into the plastic “remote control” case. The coil is not attached to the PC board – it is glued in place to the case in the cutout provided in the PC board. has a 100nF supply bypass capacitor. Construction Construction involves mounting all parts, except coil L1, on a single PC board. This is coded 04207091 and measures 78 x 64mm and is housed in a remote control case measuring 135 x 70 x 24mm. Fig.4 shows the overlay diagram. Begin by checking the PC board for shorted tracks or breaks in the copper. Check the hole sizes as well. The corner mounting holes should be 3.5mm (9/64”) in diameter, as can the two holes to anchor the battery snap leads with the cable tie. Power switch S1 also RESISTOR COLOUR CODES    No. Value 1 470kΩ 2 180kΩ 1 1kΩ 2 470Ω 1 10Ω 1 1 1 1 1 4-Band Code (1%) yellow violet yellow brown brown grey yellow brown brown black red brown yellow violet brown brown brown black black brown 42  Silicon Chip 5-Band Code (1%) yellow violet black orange brown brown grey black orange brown brown black black brown brown yellow violet black black brown brown black black gold brown mounts on the board – before assembly check that its holes are large enough and if not, enlarge slightly. Now you can begin the assembly. Install the seven resistors first. We show their colour codes in a table but it is a good idea to also check the values using a digital multimeter before installing each onto the PC board. Make sure you don’t mix up the side-by-side 470Ω and 470kΩ resistors. Doing so may not let any smoke out but it certainly won’t work when completed, either! Next, install the five PC stakes for VR1, the two stakes to terminate inductor L1 and the two stakes for test points TP1 and TP GND. Install diodes D1 to D3 and take care to orient these correctly. IC1 and IC2 can be installed, making sure that the 7555 timer is placed in the IC1 position and LM358 in IC2. Each IC must be oriented with the notch as shown on the overlay diagram. You might find some ICs don’t have a notch but will have a small dimple marking pin 1. Q1 and REG1 can then be installed but make sure each is placed correctly, as they look very similar to each other. LED1 can be installed, again taking care to get the orientation correct. The top of the LED should be 15mm above the PC board. Next, the capacitors can be installed. The three electrolytic types need to be oriented with the polarity shown but they also need to lie down to provide clearance in the box. A capacitor code table is provided to help identify the 100nF and 10nF capacitors. Trimpot VR2 can be installed either way around. Switch S1 is mounted as high as possible on the PC board but with about 1mm of pin length under the PC board to allow soldering. CON1 can now be installed. Cut the shaft of the 1kΩ potentiometer (VR1) to a length of 12mm. VR1 sits vertically with its back on the PC board surface and is secured in place by soldering the potentiometer case to the associated PC stakes. So that solder will adhere to the surface the passivated coating on the pot case must be removed by scraping with a knife or file where the PC stakes are positioned. The potentiometer terminals are soldered to the remaining three PC stakes. The 9V battery leads pass through one of the battery compartment holes in the plastic case before inserting them into the screw terminals. A cable tie secures the wires in position. The PC board is raised by about 1mm siliconchip.com.au Target Ferrous metals: LED dims Non-ferrous metals: LED brightens Helping to put you in Control Control Equipment A close-up of the coil (L1). It’s about 400 turns of wire on a plastic bobbin. Adjust for partial LED brightness away from any metal ON L A T E M R O T A LOC SILICON CHIP siliconchip.com.au This full-size front panel artwork fits into the recess on the top of the remote control case. by placing a TO-220 bush into each mounting hole from the underside of the PC board. This raises the PC board sufficiently so the switch slider is above the top of the case lid. Secure the PC board to the case with four M3 screws that screw into the integral support bushes of the case. Winding the inductor Inductor L1 is wound with 400 turns of 0.25mm enamelled copper wire on a plastic bobbin. The windings are jumble wound. This means windings do not have to be placed neatly sideby-side, layer-by-layer. The winding is held in place with a 12mm length of 20mm heatshrink tubing over the outside of the bobbin. There is no need to shrink the tubing down. The bobbin is secured to the base of CAPACITOR CODES Value µF Value IEC Code EIA Code 100nF 0.1µF 100n 104 10nF .001µF 10n 103 siliconchip.com.au the case in the cut-out area reserved for it at the front of the PC board. We used silicone sealant to glue the bobbin in place. Scrape off the enamel coating on each wire end with some fine grade abrasive paper and then solder them to the two PC stake terminals – it doesn’t matter which way around. Test & set-up Apply power and check that there is 5V between TP GND and pin 4 & 8 of IC1 and 5V between TP GND and pin 8 of IC2. Depending on the regulator, the voltage could be anywhere between 4.85 and 5.15V. Connect your multimeter between TP GND and TP1 and adjust trimpot VR2 for a reading of about 2.5V. Now set VR1 to its centre position and adjust VR2 until the LED just lights. Using it When the Metal Locator is first switched on and the LED is adjusted so that it glows dimly, there is a start up drift over about 10 seconds. During this period the adjustment will have to be altered to track the change in LED brightness. It is best to wait for the warm up period before using the Metal Locator. As mentioned the sensitive area is directly under the target printed on the top side of the case (which of course lines up with the middle of coil L1). So for detecting metal in a plaster wall, the case is slid over the wall to detect a change in the LED brightness. The adjust knob will need to be set to show some LED brightness in the absence of metal objects. The sensitivity to metal is dependent on this adjustment. If the LED brightness is set too high then there will not be a noticeable change in brightness with the unit in proximity to a metallic object. The LED will dim for ferrous and SC brighten for non-ferrous metals. Joysticks We are now selling a selection of quality Arcade style joysticks. From $27.50+GST VPacks Looking for an easy way to get a regulated 3.3V or 5 V from your AA or AAA batteries, These battery holders come with a step-up DCto-DC converter on the back. From $17.50+GST Mounting Hubs Universal aluminum mounting hubs allow you to mount custom wheels and mechanisms to 3, 4 and 6 mm motor shafts. The hubs are sold in pairs, and each hub includes a set screw for securing a motor shaft to the hub. From $11.95+GST Serial LCD SerLCD v2.5 supports 16 and 20 character wide screens with 2 or 4 lines of display. Contrast control is implemented through a trim pot on the module. Comes with 3-pin screw terminal. Adjustable baud rates 2400 to 38400 From $26.95+GST Labjack U6 DAQ A new high performance USB Data acquisition module.It features 14 analog inputs (16- to 18- bit), 2 analog outputs (12-bit), 20 digital I/O, 2 counters, and 4 timers. Comes with DaqFactory software and drivers for Windows and Labview. $475+GST RS485 Converter This simple RS232 to RS485 non isolated converter features an auto baud rate up to 115200bps. $59.95+GST Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au July 2009  43 SERVICEMAN'S LOG Car Electronics: A Whole New Ballgame As a change this month, a colleague of mine is going to talk about the confusion electronic systems in cars can cause. After all, when it comes to cars, everyone’s an expert (or has a mate who thinks he is). I’ll let him tell the story in his own words. This month, the regular Serviceman has deputised me to fill in for him. He is taking a well-earned break, away from the soldering flux fumes, the blinding oscilloscope screens and his multimeter readouts. Having had a good grounding in domestic electronics and 2-way communications, I have now owned and managed an automotive repair workshop for over 30 years. We specialise in electronics in cars in general and EFI in particular and my earlier training gives me a head-start over other mechanics when it comes to diagnosing problems in these areas. As a result, I tend to get all the “too hard” jobs that other workshops have attempted but have been unable to resolve, often after many hours of work. One of the most annoying things about clients in the auto repair game is trying to diagnose faults based on the information given by the said client. If you go to your local GP for any health issue, you don’t tell him which procedure you would like performed on your body. You certainly wouldn’t consider telling the doctor that you wanted your appendix removed, just because you had pain in that area, or having your knee cartilage scraped because your mate told you it needed to be done. However, when it comes to cars, most owners become instant experts and that certainly applies when it comes to the electronic systems and components. Many clients bring their car in and ask us to clean the injectors or to “tune” the engine, without telling us what the actual problem is. Another common request is to have the ABS (anti-lock braking system) diagnosed and overhauled. I have also lost count of those who simply want the car’s ECU diagnostic codes read and/or printed out, without mentioning why they need this information. Life for the automotive technician (a 21st century car mechanic) would be much easier if customers would simply come in and tell us, in plain English, what the real problem is, instead of muttering about ECU codes and other mumbo-jumbo that they don’t really understand. Why not just say “the car is running roughly”, or “it’s using too much fuel” or “the engine stalls in traffic”, or “the car shakes when the brakes are applied”. The technician could then check that section of the car concerned, diagnose the problem and quote on a repair based on his skill and experience, rather than on the “gut feel” of the owner or the “expertise” of his mate. Blaming the injectors Perhaps because their operation is relatively easy to understand, the poor old EFI fuel injectors cop the blame for all sorts of problems – everything from excessive fuel consumption, to engine misfiring when hot, to intermittent nostart situations. The simple facts are, they cannot affect any of these. The “excess fuel usage” problem is a myth originating from the days of diesel injectors wearing out, in the process causing the emission of black exhaust smoke and heavy fuel consumption. By contrast, EFI injectors do not “wear”; instead they actually clog up with deposits. This in turn restricts the fuel flow which means that they actually go “lean”, not “rich”. Partially clogged injectors only really cause issues when cold, a lean misfire being the most common. These 44  Silicon Chip siliconchip.com.au brakes and automatic transmissions not achieving their normal full range of gear shifting. Fixing a Camry problems all but disappear once the engine is up to operating temperature. Excess fuel usage has so many causes that one could write a book about it. However, if it is suspected, the first thing that needs to be established is what that actual consumption figure is. An interesting anomaly is that such complaints increase markedly as the price of petrol increases. In fact, it is invariably just the dollar consumption that increases, not the litres consumption. That aside, if increased fuel usage is a problem, the first step is to establish how many litres the vehicle is consuming for every 100km kilometres travelled (l/100km). To cut a long story short, any electronic causes of excess fuel usage that don’t also cause other driveability issues are usually limited to the failure of the oxygen sensor (or sensors in some cars). ECU failure, wiring issues and failures in other sensors are relatively rare on properly serviced cars that have done less than 250,000-300,000km. However, oxygen sensors are similar to spark plugs in that they have a finite life. Most have outlived their serviceable life by 150,000km. Even so, the most common causes of heavy fuel consumption are more mundane and include things such as spark plugs, leads, coils, fuel pressure regulators and driver behaviour. Other causes include mechanical issues such as low tyre pressures, dragging We had a 1998 Toyota Camry 4-cylinder come in recently, its owner complaining that he had already spent his last two weeks pay having the injectors removed and cleaned, the ECU bench tested and numerous parts replaced, including various filters, the air-flow meter, the coolant temperature sensor, the fuel pump and the spark plugs. This work had all been done by a local mechanic at his insistence, in an effort to reduce the mysterious disappearance of extra litres of the precious petroleum liquid. Fortunately, he revealed all this to us before work commenced and he was actually asking us for advice rather than relying on his own skills. Checking the basics quickly revealed a non-responsive oxygen sensor and tyres that were running very low inflation pressures. Low tyre pressures cause problems in two ways: (1) by increasing the rolling resistance (drag); and (2) by lowering of the overall gear Wanted: Electronics Technician An experienced electronics technician is required to repair & overhaul complex electronics equipment in our modern Hornsby workshop. Email your application to: ELECTRONICS SPECIALISTS TO INDUSTRY AND DEFENCE siliconchip.com.au SWITCHMODE POWER SUPPLIES PTY LTD (ABN 54 003 958 030) 1/37 Leighton Place, Hornsby, NSW 2077. email: martin.griffith<at>switchmode.com.au Phone (02) 9476 0300 webpage: www.switchmode.com.au July 2009  45 Serr v ice Se ceman’s man’s Log – continued ratio (not to be underestimated). Some complimentary fresh air, a new oxygen sensor and an invoice for $297 put a happy customer back on the road in quick time. Look for the obvious A similar scenario was played a few months ago on a 10-year old VT Commodore Executive. A colleague from the northern suburbs who wasn’t “full-bottle” on ABS electronics re­ commended the owner to us. The symptoms were violent vibrations through the steering wheel under heavy braking. In our colleague’s defence, he hadn’t driven the car and was only asked to diagnose the problem after the owner had already spent his hard-earned dollars elsewhere, to no avail. He didn’t have the time (or perhaps the inclination) to attempt the job, so he passed it on to us. The original repairer had replaced the entire ABS actuator and module assembly, along with all four wheelsensors (at a 4-figure sum). They had then pressure-bled the entire system after a cursory examination of the brakes themselves. However, there was no indication (using diagnostic scanners or otherwise) that there were any ABS issues at all. The repairer should have had a closer look at the badly cracked, undersize and discoloured front disc rotors before assuming the worst. A new pair of front rotors and better 46  Silicon Chip quality pads solved his hideous brake issues and saw the owner on his way. Common sensor problems Simply measuring in-circuit voltages or looking at sensor output waveforms are the easiest and best forms of diagnosis for many electronic problems in cars. However, many technicians depend heavily on reading built-in diagnostic fault codes and measuring individual sensors out of circuit, without checking the basics first. One of the most common sensor “failures” is that of an open circuit in the coolant temperature circuit. It is always assumed that the poor old sensor is the culprit and so it is often just replaced as a matter of course, without measuring any voltages. Some of the more “clever” technicians first unplug the “offending” sensor and measure its internal resistance. The technician is then mystified. If the sensor is OK, why does the ECU throw up a code for a faulty sensor? Well, the ECU hasn’t actually condemned the coolant sensor; all the dumb processor knows is that the voltage in that loop is abnormally high and therefore the circuit appears to be open. The most common single fault in these instances is simply a corroded or loose connector plug at the sensor. The various plugs and connectors in the engine bay live in a very hostile environment, with oil, water, excess heat and vibration present year in and year out. When compared to those that live in static, domestic surroundings, it’s not hard to understand why they sometimes fail. Virtually all EFI systems since the year dot have an engine temperature sensor of some type (usually measuring coolant temperature), so these problems have been around for two generations and yet are still wrongly diagnosed. Another common cause of electronic maladies in the automotive field is that of faulty earth circuits. An engine is often not “earthed” very well. After all, the power plant is usually mounted on neoprene rubber mounts with some fairly ordinary earth links back to the body and/or chassis. In years gone by, this wasn’t a major issue, as there weren’t many vital electrical items involved with engine operation. As long as the ignition system saw around 12V, the starter motor had a good supply of heavy current for starting and the alternator kept the battery charged, no dramas were generally seen. These days, with EFI, ABS, traction control, electronically-controlled automatic transmissions, drive-bywire throttle control and modules controlling just about everything in the car, those missing millivolts are of the utmost importance. Whether the cause is deterioration due to wear and tear or poor wiring design, bad earth circuits are more common than many technicians realise. Once again, they often chase their own backs by using diagnostic fault codes as the main line of defence, rather than checking a few basics first. If I’m looking for a weird fault in an automotive electronic system, the items I always check first are: loose/ corroded battery terminals, any wayward voltage between engine and body earth, the alternator charge rate and the operation of all warning lights on the instrument panel. With oxygen sensors oscillating either side of 500mV at a few hertz, a floating earth can negate its operation completely, yet not illuminate the “check engine light” or throw up any fault codes. The same applies to thermistor type sensors. In cars with boot-mounted batteries, ECU-controlled alternator regulators and serial-BUS or CAN-BUS communication between the various control modules, these up-front basic checks are essential. siliconchip.com.au A few of these BUS systems can have problems of their own. A commonly seen Bosch ABS system (version 5.3) fitted to many makes of car (everything from Toyotas, Holdens and Fords to Saabs, VWs and Audis) has an issue whereby open-circuit internal links not only cause ABS and traction control problems but also affect all other ECUs on that BUS line. We’ve had cars towed into the shop because this “small” ABS drama has locked the automatic transmission into third gear only (limp-home mode), switched the engine cooling fans to full speed and played havoc with all instrument warning lights and gauges. In addition, it affects engine ECU operation and disables the air-conditioning system, making the car all but undriveable. This problem is now so common that these ABS modules are available as off-the-shelf re-manufactured exchange units. Fortunately, the cause was eliminated in later versions of this ABS system and so it doesn’t occur in late-model cars. ECU failure is rare Engine or transmission ECU failure is a rare event for the most part but there are exceptions. There are a handful of popular cars where ECU problems are to be expected in the medium term, regardless of the kilometres travelled. For example, some Mitsubishis manufactured in the 90s have issues with electrolytic capacitors leaking over the PC board. The leakage permeates the protective lacquer and usually shorts out copper tracks on the board’s surface. The 12V rail can short to anything close by and this can be to an earth track, causing severe charring of the board and all components in that area. Alternatively, it can short to a 5V rail, often destroying any semiconductors or processors in the vicinity. Many of these items are custom-designed for the purpose and therefore unobtainable through normal channels, deeming the whole ECU an irreparable write-off. In other cars, the ECUs can suffer from good old dry joint issues or worse, corrosion from water entry due to a leaking windscreen or heater core. However, most EFI electronic siliconchip.com.au Professionally Designed and engineered in Australia using Peerless speakers which are known and respected across the globe. Remarkable Cross-over design, built using the highest grade components designed to give maximum clarity and responsiveness for voice and tonal reproduction. For More Info Please visit: www.wagner.net.au/speakers www.d-s-t.com.au/speakerkits We stock everything you need for your Audio Visual installation including HDMI & RCA Interconnect, Plasma / LCD TV Wall Brackets, Speaker cabling, Plugs & Connectors, Tools and Soldering Equipment, Plus Lots More!! View our Catalogue online. Visit Us Online: www.wagner.net.au Email: sales<at>wagner.net.au July 2009  47 Phone: 02 9798 9233 138 Liverpool Road, Ashfeild, NSW, 2131 Serr v ice Se ceman’s man’s Log – continued A Strange Problem Actually, I did manage to sneak one story in this month, although I must confess that it’s one that was held over from the previous issue. It’s one of the strangest problems I have ever had to deal with and it involved a set belonging to a young lady with severe peripheral vision. In fact, her condition was so bad that she was classified as legally blind. Her problem was that she was having a great deal of difficulty operating her JVC AV-21BS26 CRT TV. This is a silver TV with silver-coloured controls, which made them difficult for her to recognise. Apart from the flush-fitting power switch, these controls (Menu, Channel & Volume) are all hidden underneath an adjacent flap, which problems are usually seen under the bonnet and not in the ECU itself. Automotive design and their associated electronic systems have advanced so quickly in the last two decades that, 48  Silicon Chip only added to her difficulties. In addition, the remote control is all grey, so it too was difficult for her to operate. Adding to her woes, the reception in the Housing Commission village where she lived was quite poor. As I later discovered, this was due to the ancient Concordia coaxial cable used to distribute the antenna signal. This cable was also acting like an antenna and picking up signal, the end result being leading-edge ghost images. Finally, every time she changed any of the control settings on the TV, the command was accompanied by two deafening beeps that could be heard by her neighbours. So that also had to be solved. I decided to start with the extremely annoying loud beep. I couldn’t find a reference to it in the set’s instruction book, nor could I initially find it in any of the OSD menus. However, after some searching, I eventually found it in the install menu after scrolling in my humble opinion, it’s time for a moratorium on further development to allow the service and parts industry to catch up. I know from personal experience that the same issues exist in the down to reveal two extra items at the bottom. The first of these items is the blue screen mute option and the last one lets you turn off the beep. There was no easy fix for the aerial system, except to use a Digital SetTop Box (DSTB). Unfortunately, her JVC TV had a sloping back, so the DSTB couldn’t sit on top, which was rather inconvenient. Another problem was that in order to select the TV’s AV input with the remote, you had to cycle through all the options until you got to AV1. Unfortunately, her set did not have last-state memory, so she would have to go through that exercise every time she switched the set on. However, that just wasn’t practical, because it was difficult for her to see which input had been selected each time the mode button was pressed. In the end, I swapped her JVC set for a rather nice Sony KVG-21S1 which I happened to have in the workshop. This Sony set has a flat top to rest the DSTB on and can also start and stop in the AV mode so she doesn’t have to select it each time. In short, it was much more convenient for her to operate. The DSTB fixed her reception problems too and I skipped all the channels she didn’t want with the exception of Ch4 which is an orange digital program guide. This gave her a reference point she could actually see clearly and from which she could count sequentially to the program she wanted. I contemplated covering the remote buttons other than on/off, channel up and down and volume up and down buttons so that she couldn’t inadvertently press the wrong one. However, this wasn’t practical and in any case wasn’t necessary as the customer sits so close to the set that a remote control isn’t necessary. Instead, she came up with her own simple solution: orange dot stickers on the Volume and Channel buttons on the TV, so that the black buttons could be seen against the black cabinet. domestic electronics industry, where service technicians are forever playing catch-up obtaining the necessary equipment, literature and knowledge SC to service the latest gear. siliconchip.com.au R O F S L TOO YOUR TRADE Wireless Weather Station WOOLOONGABBA STORE REFURBISHED STORE A feature-packed weather station for the enthusiast forecaster. The outdoor sensors will wirelessly transmit real-time indoor/outdoor temperature, relative humidity, rain, wind speed, wind chill, dew point, and barometric pressure. All minimum and maximum values with the date and time it was recorded are stored for your reference. Along with its storm warning feature, you can set programmable alarms to alert you when certain weather parameters fall above or below a limit you determine. If you enjoy outdoor activities this is a great tool to inform you of ideal weather conditions or to keep you a step ahead of potential hazards. See our website for full details. $ 149 New Touch Screen Wireless Weather Station with USB also available. This highly advanced weather station features a touch screen panel that you can connect to your computer through USB for storage and a more accurate analysis of weather data. XC-0348 $199 Cat: XC-0346 Coax Connector Bargains Surplus Stock Attention Radio Amateurs A 1.7m length of high-quality 50 ohm coax terminated with a PL-259 UHF connector & a 4-pole connector with 4 unterminated wires at the other end, all encased in a flexible PVC jacket. You can easily strip the outer jacket and just have the coax and connector, and keep the wire (the nicest hookup wire you’ve ever seen in 4 colours) for your scrap box. Cat. WC-7810 $7.00 (Pk 10) $ 15 Pk 10 Cat: WC-7811 $ 7 Pk 10 Cat: WC-7810 The same as above except the coax is 6.2m long and has a UHF connector and a 4-pole connector at each end. The 4-pole connectors are male/female. This assembly would be ideal when you have to switch equipment at the antenna end of a ham rig. Cat. WC-7811 $15.00 (Pk 10) Ideal for camping, 4WD, boating, caravans or motorhome holidays. Take the guesswork out of installing your Digital TV antenna to get the best signal. With this handy little signal strength indicator, you get a clear visual LED indication of the signal strength coming from your antenna as you adjust the position and direction. No more yelling from the roof to the living room! Note colour may vary from photograph shown. 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It has a robust nylon fabric enclosure and cigarette lighter socket for powering whatever you need. Also includes utility loops so you can tie it up in a convenient place to catch maximum sunlight. Two lead sets are included - one with a cigarette lighter plug and another that terminates to alligator clips. Digital TV Signal Strength Indicator Much cheaper than the hardware store and with 400 pieces, this kit will service every bit you will ever need. Housed in a plastic case. Case measures: 210(W) x 300(H) x 70(D)mm Folding Solar Charger 20W Due Mid July Rotary Tool Bit Set - 400PC $ Note: These cable assemblies were made for a military communications application, are only 3 months old and are of outstanding quality. Please note that they are only sold in packs of 10 cable assemblies. • Dimensions: Open: 965(L) x 362(W) mm Folded: 375(L) x 120(W) x 45(D)mm 65 Ipswich Rd Cnr Wilton St Qld 4102 Ph: (07) 3393 0777 399 Multi-Function Filter Module Ref: Silicon Chip Magazine July 2009 A very versatile active filter module that could be used as an active crossover in a speaker project, a low pass filter for a subwoofer, or a high or band pass filter simply by changing a couple of jumper links. Being an active circuit, you'll need to $ add a power supply (see specifications on our website) and amplifiers for the drivers. Short form kit only. 24 95 Cat: KC-5480 Turntable/ CD player Dust off those old LPs! This player includes a turntable, AM/FM stereo radio, cassette deck and a programmable CD player all encased in a cherry wood finish cabinet with two front stereo speakers. See our website for specifications. Plays 12" LPs & 7" EPs records - 3 speeds 33/45/78rpm • Measures 390(L) x 360(D) x 260(H)mm • Ask us how to back up your LPs to CD $ 199 Cat: GE-4063 To o l s f o r yo u r Tra d e TEST & MEASUREMENT Thermocouple Thermometer 2 Input Fast response and laboratory The soldering station features a high quality ceramic heating element for accurate temperature control, which is adjustable between 200 and 480°C. The soldering pencil is light weight, making it comfortable for use for extended periods. accuracy, works with K-type thermocouples and offers 0.1 or 1° user-selectable resolution over the entire measurement range. You can monitor two separate temps or use the differential function to compare them. • Auto power off • Backlit LCD • Max and hold function • Celsius & Fahrenheit $ • Holster included • Thermocouples included 99 95 Cat: QM-1601 Cat III DynamoPowered DMM This dynamo powered DMM requires no batteries. Just crank the handle for 10 seconds to provide power for about 10 minutes operation. Ideal for electrical emergencies on the car or boat. It also has provision to be powered by 2 x CR2032 batteries. $ 99 95 • No batteries required • Capacitance and frequency • Data hold • 10A current Cat: QM-1547 Cat IV 600V/ CAT III 1000V DMM Ergonomically designed slim shape with one hand operating knob and buttons. It has overload protection, easy battery replacement, and is compact, yet extremely rugged. This DMM would be an excellent investment for the apprentice to the professional tradesman. $ This meter is supplied with a protective Cat: QM-1623 holster and test lead. • Dimensions: 164(L) x 82(W) x 44(D)mm • Large scale display • Auto power-off • Display: 4000 count • Category: Cat IV 600V • Basic DCV accuracy: 0.500% Cat IV Fixed Jaw Clampmeter The ideal test instrument for electrical contractors. Compact and light with probe storage in the back for easy one-handed operation. Jaw opening is 16mm. • Non-contact voltage sensor $ • Data hold • Auto power-off Cat: QM-1567 • Diode test • Audible continuity test • Category: Cat IV 600V, Cat III 1000V • Display: 2000 count • Dimensions: 190(H) x 62(W) x 42(D)mm 179 This is a full featured meter with plug-in 4mm probes AND transistor tester. It is the ideal first multimeter and will give years of faithful service. $ 9 95 • DC Voltage: 200mV Cat: QM-1500 to 1000V • DC Amps: 200uA to 10A • AC Volts: 200V to 750V • Resistance: 200 ohm to 2M ohms • Size: 125(H) x 68(W) x 23(D)mm 2 • Temperature Range: 200 - 480°C • Accuracy: +/-10°C Ideal for the hobbyist and handy person. Has a stainless steel barrel and orange cool grip, impact resistant handle. 13 95 Cat: TS-1465 $ 109 Cat: TS-1560 Super Pro Gas Soldering Tool Kit Kit contains a Portasol Super Pro Gas Soldering Iron, and all of the following parts: $ SOLDERING EQUIPMENT 25 Watt Soldering Iron $ Spare tip available - TS-1466 $3.95 Gas Soldering Iron / Torch Kit Everything you need to solder, silver solder, braze, heatshrink, strip paint etc. Refillable with stand, extra tips, torch and cutting attachment. 159 Cat: TS-1328 • Quality storage case • Cleaning sponge & tray • 2.4mm double flat tip • 4.8mm double flat tip • Hot air blow Electrical Tester with Polarity Checking and Light 199 Low Cost DMM 50W Temperature Controlled Soldering Station Designed for maximum safety. The probes have a good grip and are IP64 rated. Testing voltage is simple and the unit's LED display will indicate to the nearest voltage up to 690V with polarity indication. This unit will also check for low impedance, continuity, do a single pole phase test and show rotary field indication. A LED light is included for dimly lit locations. $ 49 95 Cat: QP-2286 • Requires 2 x AAA batteries (included) • Voltage test works without batteries • 3 soldering tips • 1 torch attachment • 1 rope cutter $ 39 95 Cat: TS-1112 VOLTAGE DETECTORS Telescopic AC Voltage Detector Test for mains voltage in confined or inaccessible areas such as wall and ceiling cavities, behind furniture, under floors etc. Ideal for shop fitters, chippies, plumbers and other tradesmen to check that there’s no nasty surprises before you sink a drill through the gyprock and end up with an afro or worse - go home in a pine overcoat. Batteries included. Fold to a handy pocket size for easy storage. $ 22 95 • LED indicates mains voltage Cat: QP-2279 • Cat II rated • Extends to over 1.2m • Size folded: 180(L) x 32(W) x 16(D)mm ABS INSTRUMENT CASES - IP65 Rated These are excellent cases and you will be hard pressed to find a better product anywhere near the price. Ideal for photographic gear, test and measurement equipment, scientific and medical equipment etc. • Each has a soft pluck foam insert with pre-cut squares that can be removed to snugly fit the item you want to protect. • The lids are also lined with eggshell foam, and are secured with strong snap closed fasteners with a gasket seal that is waterproof and dustproof to IP65. FROM Four sizes available with 2 year warranty: MP1 Cat. HB-6380 $49.95 $ MP5 Cat. HB-6384 $139 Internal: 240(W) x 160(H) x 92(D)mm External: 260(W) x 180(H) x 100(D)mm Internal: 359(W) x 239(H) x 152(D)mm External: 380(W) x 260(H) x 160(D)mm MP3 Cat. HB-6382 $89.95 Internal: 310(W) x 190(H) x 112(D)mm External: 330(W) x 210(H) x 120(D)mm MP6 Cat. HB-6386 $159 Internal: 399(W) x 279(H) x 110(D)mm External: 420(W) x 300(H) x 120(D)mm 49 95 All savings are based on original recommended retail prices. To o l s f o r yo u r T ra d e 1000V- 7 Piece Screwdriver Set High quality, bright red drivers you can find easily. Insulated right to the tip and rated to 1000V. Drive sizes: Flat: 1.2x 6.5 x 150mm, 1 x 5.5 x 125mm, 0.8 x 4 x 100mm, 0.6 x 3.5 x 75mm. Phillips: #2 x 100mm, #1 x 80mm, #0 x 60mm. Includes storage box. 29 Piece Tool Kit With Case DIY minor repairs are a breeze with this 29 piece tool kit and every DIY guy should have at least one of these in easy reach. Includes torch. $ See in-store or our website for a full tool list. 24 95 See website for full listing $ Cat: TD-2022 6-in-1Compact Screwdriver $ 34 95 TD-2032 Driver handle to suit $6.95 • Torch requires 2 x AA batteries (not included) • Case measures 200(L) x 145(W) x 45(H)mm 10 Piece Spanner Set This innovative screwdriver has six of the most useful blades. They are made of a vanadium and molybdenum alloy and stored neatly in the handle. This may just become one of the handiest tools in your kit. Supplied with the following blades. $ 95 • Slotted: 4, 5, 6mm • Phillips: #1, #2, #3 Cat: TD-2028 • 128mm long 18 Ideal mini spanner set. Set of 10 pieces, open end/ring combination. Suitable for light hobby use. • Sizes 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 11mm • Supplied in a plastic wallet Heavy Duty Wire Stripper $ 6P/8P Modular Crimp Tool This tool will crimp 6P2C, 6P4C-RJ11, 6P6CRJ12 &8P-RJ45 plugs. Also cuts and strips the cable. $ 29 Measure the temperature of a surface from a safe distance. Dual laser sighting for accuracy. $ Temperature range: -50° to +650°C Cat: QM-7221 119 95 • Response time: <150ms • 140mm long Cat: QM-7217 Flow Rate Sensors These flowmeters provide simple DC output pulses in proportion to supply voltage and fluid flow which makes interfacing easy. Both have impellers made from acetal and stainless steel shafts, so will work with low viscosity fluids. Two types: Cat. ZD-1200 $49.95 Cat. ZD-1202 $49.95 For full specifications, see page 29 of our 2009 Catalogue or on our website. $ 49 95 Cat: ZD-1202 $ 49 95 Cat: ZD-1200 Cat: TD-2038 Computer Service Tool Kit Ideal for computer service technicians or the talented amateur. Kit includes: IC inserter/extractor, Pearl Catch, Tweezers, 1/4" Nutdriver, 3/16" Nutdriver, Double ended 10/15 Torx driver, Parts tube for storage, #1 & #0 Phillips screwdrivers, 1/8" & 3/16 Slotted screwdrivers, Zipper case, Size 220 x 155 x 38mm $ 29 95 Cat: TD-2040 All the heatshrink the technician, tradesman or serious hobby user will ever need. The pack contains 160 lengths of different sizes from 1.5 to 10mm in black, red and clear in a handy storage case. $ • Case size: 205(L) x 110(W) x 35(H)mm Non-Contact Thermometer with Dual Laser Targeting Suitable for lab, chemistry and industrial applications. It measures in Celsius and Fahrenheit and has a stainless steel probe and protective cap. Batteries included. Hall Type 1.5 - 25 litres per minute Reed Switch 0.6 - 8 litres per minute 19 95 Cat: TH-1935 Probe Thermometer 19 95 Heatshrink Assortment Trade Pack 17 95 Cat: TH-1910 Designed for easy wire stripping of AWG 10-24 gauge cable (0.13 6.0mm). The wire guide ensures the correct length is stripped. A precision blade is incorporated for easy wire cutting. Also features quality crimping jaws. $ 95 • For 1.5 - 6mm terminals • Spring return Cat: TH-1827 34 This is an excellent driver bit set that contains just about every bit you could ever use. It has a magnetic holder, adaptors, Phillips bits, slotted bits, torx, tamperproof, pin drive, and even a wing nut driver - Fantastic. • Metric and Imperial sizes Cat: TD-2066 • Auto power-off and low battery indication • Data hold $ • Range: -50 - 270°C. (-58 - 518°F) • Resolution: 0.1°C (1°F) • Accuracy: 1.5% • Dimensions: 185(L) x 36(W) x 19(H)mm 100 Piece Driver Bit Set 24 95 Cat: WH-5524 THERMOMETERS IR Non-Contact Pocket Thermometer Take quick and accurate temperature measurements of any surface without touching it. Handy for the house or garage. LCD displays temperature in Celsius and acquires a reading in less than two seconds. • Accuracy: ±1% • Range: -50 - 220°C • Handy pocket clip • Batteries included • Size: 85(L) x 15(Dia)mm $ 49 95 Cat: QM-7219 Electronic Flow Rate Meter with LCD Completely self-contained, this unit only measures 60 x 40mm and includes a full LCD information display. It's supplied with a reed switch and piezo alarm. It operates from 2 x AAA batteries and a battery holder is included. When used in conjunction with the FS-300AH Digital Flowmeter (Cat ZD-1202), it will count down (in litres) from a predetermined volume, for example 500 litres. When 500 litres have gone through the flowmeter an alarm will sound. The alarm signal can be used to trigger another slave device. As it goes up to 99,500 litres, it could be used in larger-scale applications such as irrigation or just to let you know when it's time to clean a filter. It also reads flow rate, will remember data and operate in time mode. An unbelievably fantastic product! • Full data sheet & instructions included • PCB/LCD size: 60(L) x 40(W)mm Free Call: 1800 022 888 for orders! www.jaycar.com.au $ 69 95 Cat: ZD-1204 3 Great Gift Ideas for Christmas in July! 1:12 Scale Casey Stoner RC Motorbike 4 Channel Mini RC Helicopter with Remote Recharge For the Motorbike Enthusiast! The smallest 4 channel RC helicopter on the market, this little beauty is a joy to fly. Surprisingly easy to control and stable in flight, it comes ready assembled with a true 4 channel remote. Running low on power? Just simply attach the helicopter to the IR remote to recharge it for 17 minutes, and you're up, up and away again. A replica of Casey Stoner's 2007 Moto GP Championshipwinning 800cc Duke with full function digital proportional remote control. It also has a fully functional replica Casey on board who leans into every corner like a real rider. A highly detailed model complete with slick tyres, working front and rear suspension and display stand. • Steering trim alignment • Brake endpoint adjustment • Throttle curve selector • 27MHz • Measures 175(L)mm • Suitable for ages 10+ • 17 minutes recharge for 5-7 mins flight time • Weighs 19g, 190mm long (220mm inc. blades) • Requires 6 x AA batteries • Suitable for ages 14+ $ 19 $10 39 95 Cat: GT-3276 • Requires 6 x AA batteries • Wingspan: 310mm • Suitable for ages 8+ Was $49.95 Forget about reading National Geographic while you're indisposed just play with the sudoku loo roll! After you've finished, put it to good use! • Double ply for comfort USB Missile Launcher with Web Cam Upgrade to the latest in workstation weapons. This USB missile launcher is equipped with a detachable webcam and software, which allows you to communicate via the MSN Instant Messenger service. Also now with added sound effects! $20 $ 89 Cat: GE-4084 $ 14 95 Cat: GE-4089 Was $19.95 *Laptop not included 4 $ $ 199 29 95 Cat: GH-1122 Cat: GH-1372 Create a dazzling lighting effect with this USB powered plasma ball that will surely impress your colleagues! As the ball becomes energised, the gases inside light up and turn into plasma. By touching the outside of the ball, you can produce amazing effects. System requirements: • Windows XP or Mac OS X • USB 1.1 port • Measures: 130(H) x 100(W)mm Cat: GT-3263 • Requires 4 x AAA batteries • Handy belt clip • Up to 130 x magnification • USB powered • Approx 150mm tall • Up to 640 x 480 image resolution • 5 x optical zoom Was $99 USB Plasma Ball 169 Next time someone starts going on about synergies, tipping points, end-state visions and stakeholder partnering, you can just turn on your Bullsh*t Detector and shut them up with one of nine anti-bullsh*t messages. 69 Cat: GH-1508 $ Remote Control Bull SH*T Detector A terrific introduction to the microscopic world of nature. It works with your computer by displaying the camera's output onto your monitor and at the press of a button you can $ capture the digital images for projects etc. Cat: QC-3244 5 95 • 3 foam WMDs inlcluded • Shoots up to 5 metres • 110(W) x 125(D) x 185(H)mm Limited Stock Was $109 Store your best wine and keep them chilled in this wine cooler. It has a capacity of 18L, holding up to 6 wine bottles and uses Peltier thermoelectric modules to cool the wine bottles 18 degrees below ambient temperature. • Mains powered • Power consumption: 56W • 245(W) x 380(H) x 510(D)mm USB Digital Microscope Camera System Sudoku Toilet Paper $ GT-3300 GT-3301 GT-3302 GT-3303 GT-3304 GT-3305 6 Bottle Wine Cooler Generating a lot of lift from the wide rotors gives this slightly weird machine very stable flight. It's made of durable foam, so will take a few knocks from dodgy landings and armchair pilots. 20 minute charge from the remote unit provides about 8 minutes of flying time. $ • 20 minutes charge gives about 10 minutes flight time • Rechargeable 7.4V 1000mA Li-Po battery • Frequency: 40MHz • Requires 8 x AA batteries • Recommended for ages 10+ Spare Parts Available • 7.4V 1000mAh Rechargeable Battery $44.95 • Stabiliser Bar Pk 2 $6.95 • Gear Shaft B $9.95 • Drive Gear $4.95 • Tail Rotor Rack $6.95 • Connecting Buckle $1.00 Remote Control UFO Cat: GT-3279 Four channels gives you the full range of control - up/down, forward/back, backleft/right, and rotate-left/right. Finished in jungle camo. 149 $5 Not just a display piece, this 1:64 scale F430 Ferrari has rear wheel drive an adjustable steering bias to ensure a straight and smooth ride. It is finished in Ferrari red with remote control stored in display base. • Requires 6 x AA batteries • Recharges from display base $ 95 • Suitable for ages 10+ Cat: GT-3213 Was $24.95 79 95 Apache 4 Channel RC Helicopter Cat: GT-3690 RC Miniature F430 Ferrari $ $30 Alien Doorbell Who's at the door? A friend, or an invasion of aliens? When someone comes calling, the flying saucer speaker will deliver noises of a spaceship landing or an alien greeting. • Requires 1 x 9V, 4 x AA batteries • Indoor use only. • Suitable for ages 5+ Was $39.95 $ $10 29 95 Cat: LA-5019 $5 USB Ultrasonic Cool Mist Humidifier Not only can it help reduce allergens, it also keeps the skin hydrated making you look & feel younger. Simply plug into your computer's USB port to keep you fresh & alert day after day. • Unit measures: 90(L) x 83(W) x 128(H)mm Limited Stock Was $39.95 $ 29 95 Cat: YH-5460 All savings are based on original recommended retail prices. $10 Great Gif t Ideas For Christmas In July! USB Slide/Film Scanner DIGITAL PHOTO FRAMES 3.5" Digital Photo Frame $10 Displays single frame photos or slideshows, this mini Convert your negatives and slides to digital images quickly and easily with this USB scanner. Images are scanned in about half a second for high-speed conversion & editing using the included Arcsoft Photoimpression software or one of many other image management programs. • Colour or B&W film or slides • Negative & slide holders included • 1,800 dpi resolution • Windows XP, Vista $ 199 digital photo frame is ideal for your desk at work or home and can read from an SD or MMC card up to 2GB. USB or mains powered. Cat: XC-4881 • Supports JPEG image format • Plugpack included • Size: 108(W) x 84(H) x 20(D)mm USB 2.0 DVD Maker Turn your aging collection of VHS and Betamax video tapes into new video productions or record live video straight to your DVD or CD burner. This new and improved version works with a Mac & Windows, allowing you to publish your videos on to web application and many more features. $ Cat: QM-3779 Limited Stock Display your favourite photos or videos. You can control all of the functions with the remote control or leave the automatic slide show display running. USB or mains powered. 99 $ Plug in your iPod® or iPhone® and listen to music through your car's FM radio. If you get a call, you use the phone hands-free without losing the music. • 16:9 aspect ratio • SD/MMC/MS card compatible • Supports JPEG format • Supports MPEG1, MPEG2 and MPEG4 • Plugpack included • Dimensions: 202(W) x 150(H) x 20(D)mm Display your digital photos or videos with an MP3 file for background music if you like. The files can be loaded via a compatible memory card or via a USB cable (available separately). You can control the display for individual images, a slide show or thumbnails with the remote or with the $ built-in keys. Was $274 Limited Stock Cat: QM-3768 119 Cat: AR-1868 Limited Stock Record and encode stereo audio MP3 straight to your iPod® - no computer required! Simply connect an audio source to the dock and record via the voice/memo recording mode. You can adjust the $ recording level and also sync to your PC via the USB port. Component/Composite Video to VGA Converter 119 Cat: AA-0498 • Suits iPod® Classic, Touch, Nano 3G and 4G • Mains plugpack included • Dimensions: 100(L) x 100(W) x 35(H)mm Infrared Digital Pen and Notetaker $19 USB Digital TV Tuner Watch high definition digital TV on your desktop or laptop. Simple to set up and use, just connect the USB stick, plug in the antenna, install the software and away you go. Perfect for Students or Meeting Notetakers! 160 Cat: XC-0355 $ 79 95 Cat: XC-4886 USB RJ45 Extension Adaptor Connect any USB device to your computer from up to 50 metres away via a standard Cat 5 network cable. Now you can have your printer, webcam, keyboard, mouse or any other USB device exactly where you want it without having to move your computer around. • PC and Mac compatible • Requires standard Cat 5e cables • Supports USB 1.1 • Transmitter and Receiver included $ $ This compact converter box accepts a range of video input signals and converts them to VGA specification for use on CRT, LCD, etc. Also accepts YPbPr input for DVD players, Xbox®, Wii®, or other video sources up to 1080i. Simple on-screen set up. No software required. 109 Cat: XC-4873 • Includes remote control • 145mm wide • For full specs see website Note: iPod® not included Just clip to any A4 sheet of paper, start writing or drawing and everything you enter will be captured electronically. Two modes of operation: Mobile mode allows you to take and store notes (up to 100 A4 pages) while away from your computer in meetings, lectures or conferences; or Online mode, where you use it like a tablet PC connected to your computers USB port. Simple and intuitive to use: like putting pen to paper. Software included. $25 249 Dock Recorder for iPod® $ Was $99 Limited Stock 10" Electronic Photo Frame • USB port • 3.5mm input jack for audio auxiliary input • Gooseneck: 200mm long • Size: 140(H) x 75(W)mm $ 89 Cat: QM-3777 Was $59.95 7" Digital Photo Frame Cat: XC-4867 Hands-Free Bluetooth FM Transmitter • Rechargeable battery on receiver unit • Battery status indicator • Standard off-the-shelf ink refills Was $179 49 95 $10 • Supports USB 1.1 & 2.0 Plug-and-Play • Stereo audio input via RCA connectors • Dimensions: 35(W) x 95(D) x 15(H)mm Note: iPod® not included $ 69 95 Cat: XC-4884 • Supports free-to-air DTV in many countries • Software with time shifting and scheduled recording • Compatible with Windows XP, MCE and Vista • Antenna, cable and software included • Supports Electronic Program Guide (EPG), subtitle and Teletext See website for full systems requirements. Free Call: 1800 022 888 for orders! www.jaycar.com.au Hollywood Camera Style USB Webcam Broadcast yourself all over the net on your USB movie camera webcam. A strong gooseneck for getting that closeup shot. • 350mm long • Image Sensor: 300k pixels • Resolution: 640 x 480 Was $35.95 Limited Stock $ 24 95 Cat: QC-3227 *Note: Laptop not included $11 5 Power Supplies Low Frequency Inverter Sinewave - 1200W Sine Wave Inverters Suited to commercial applications, this sine wave low frequency inverter uses low frequency switching with large toroid output transformers to give ultra-robust performance and surge ratings much higher than conventional switchmode inverters. This results in lower standby power, lower heating & less wasted energy from the batteries. Being a pure sine wave, you can connect any device or appliance to the output-even delicate electronics and equipment with variable speed motors. It also features a Green Power function - this is automatic load sensing which allows the inverter to remain in standby mode until an AC load is turned on. This conserves battery power as the inverter uses only about 10% of normal power when in standby mode. The amount of standby power required to start the inverter is user-adjustable. 1299 $ • Microprocessor controlled • 3m wired remote control Cat: MI-5180 • Soft Start • Fan cooled • Automatic voltage regulation • Reverse polarity & Overload protection • Input low/high voltage protection • Low battery alarm • Dimensions (L x W x H) 465 x 280 x 120mm 180 Watt 380 Watt 600 Watt 1000 Watt 1500 Watt 2000 Watt - Cat Cat Cat Cat Cat Cat MI-5160 $219 MI-5162 $269 MI-5164 $399 MI-5170 $799 MI-5172 $1099 MI-5174 $1349 3-Stage 6/12V Automatic Battery Charger Automatically diagnoses, recovers and recharges 6 or 12 volt leadacid, gel, and AGM rechargeable batteries for boats, motorcycles etc. Maintains your battery for months and extends battery life by constantly monitoring battery condition and bulk, trickle or maintenance charges accordingly. Remote Controlled 240V Mains Outlets Switch any mains appliance rated up to 10A on or off remotely. Supplied with three receivers and a remote control, you can control up to three separate devices and switch them individually. $ • Output voltage: 7.2, 14.4VDC • Capacity: 1.2 - 20Ah • Dimensions: 110(L) x 62(W) x 45(H)mm 39 $ 95 • Range: 30m • Frequency: 433.92MHz Cat: MS-6140 • Max Power: 2500W (10A) • Remote size: 100(L) x 35(W) x 20(H)mm 49 95 Cat: MB-3603 Long Life Pre-Charged Rechargeable Batteries These fantastic batteries feature ultra-low self-discharge technology and have an 85% charge retention after 1 year. They are supplied in a charged state and can be used immediately after purchase. A handy storage case is included. AAA, AA & Sub C styles are available. SB-1752 7.2V NI-MH RC BATTERIES High capacity, high current discharge Ni-MH packs for radio control cars. Fitted with standard "Tamiya" type plug. 7.2V Ni-MH 2,000mAh Cat. SB-2312 $34.95 800mAh AAA 2,000mAh AA 2,000mAh AA with solder tags 1.2V 3,000mAh Sub C with solder tags 1.2V 7.2V Ni-MH 3,300mAh Cat SB-2314 $49.95 SB-1752 SB-1750 SB-1751 SB-1759 $17.95 $21.95 $7.95 $9.95 SB-1750 Sight & Sound USB Guitar & Microphone Audio Interface USB Microphone with Stand Excellent quality reproduction on vocals, acoustic instruments or podcasting. • USB powered - no phantom power needed • Built-in volume control $ 95 • Stand with shock mount • Plug and play - no drivers needed Cat: AM-4102 See website for full specifications 99 Ideal for DIY PA bins or replacement drivers. With aluminium frames, high efficiency and power handling capacity, these drivers offer exceptional value. • Size: 100(L) x 28(Dia)mm 10" PA Driver Cat. CG-2381 Mix, play and scratch your own MP3 tracks directly from your PC. The i-Mix gives you the control you lose when going from a traditional mixer to a laptop. It sends MIDI data from the controller to your DJ software without the inconvenience of mouse control. Complete with LE versions of Deckadance & Traktor 3 $ software. This is the ultimate tool for the performing DJ. Features: Cat: AM-4250 • 2-deck controller • Mix 2 files in 1 controller • USB powered, no extra power needed System requirements: • Totally portable, smaller and lighter than a laptop • Windows XP, SP2 or Vista • 2 pro jog wheels • Pitch, search and scratch • Pentium III or Athlon 1GHz • 3 faders: 1 cross fade, 1 volume per deck • 512MB RAM • 6 EQ filters with 6 kills • Dimensions: 360(W) x 202(H) x 45(D)mm 399 GUITAR PRACTICE AMPS Practice amps with enough volume for the odd garage jam. They have a headphone jack so you can play until your fingers bleed without upsetting the neighbours. 69 95 Cat: CS-2554 Paper Cone PA Drivers Simple, passive single unbalanced input audio interface for home recording or webcasting. It works on PC or Mac, requires no drivers or setup and is powered by the USB port. $ I-Mix Club USB DJ MIDI Controller • 6" speaker • Headphone jack $ • CD input • Switchable distortion • Mains powered • Dimensions; 250(W) x 315(H) x 205(D)mm Our pure sine wave inverters are able to provide bundles of power in mobile and permanent installations. In addition to the normal 240VAC outlet, all models also have a USB port for powering all your gadgets. This range of sine wave inverters is suitable for any application where you want to run sensitive equipment and the larger units can be used in permanent installations such as caravan, 4WD, camper or even marine. 119 Cat: AM-2037 $ Power handling: 150WRMS 12" PA Driver Cat. CG-2383 Power handling: 200WRMS 99 Cat: CG-2381 $ 119 Cat: CG-2383 Speaker Cover Suit or models CS-2514, 16, 17 &18 Protect your speaker investment from the elements while being transported or from bumps and scrapes when in storage. UV and water resistant. Suits PA Speaker and Speaker/Amp CS-2514 or CS-2517 CS-2500 $24.95 Suits 12" Foldback Speaker CS-2516 CS-2501 $24.95 Suits 12" Subwoofer CS-2518 CS-2502 $24.95 50W Guitar Amplifier also available Cat. CS-2556 $199 6 All savings are based on original recommended retail prices. IT & Comms Mini Roll-Up Wireless Keyboard 15 - 24V Laptop Power Supply Life for business travellers and students just got a lot easier. Now you can have a convenient roll-up keyboard to take on the road or to lectures, and it’s wireless. Convenient size with splash resistant keypad so is ideal for harsh environments or areas that have to be constantly cleaned such as sawmills, factories, workshops and food preparation areas. Adaptors to fit the major manufacturers' DC power input sockets, and enough grunt to suit all but the most power demanding laptop models. It also displays the output voltage and automatically adjusts output voltage according to which connector is fitted. 10 different connectors to suit a variety of different laptops. Check our website for compatibility. • Maximum power output: 90W • Voltage range: 15 - 24V • Current: 6A (max) • 138(L) x 58(W) x 37(H)mm $ • Standard QWERTY layout • Washable and hygienic • Supports Windows • Size: 370(L) x 123(W) x 15(H)mm 69 95 Cat: MP-3476 USB Optical Mouse with Number Keypad • Measures: 67(W) x 110(L) x 20(H)mm 69 95 Cat: XC-5145 IP68 Rated USB Optical Mouse Notebook computers are great when you are moving about or space is at a premium. However, the lack of a proper numeric keypad and mouse can be a real nuisance. This problem is easily fixed with this new combination mouse with built-in keypad. It simply plugs into the notebook computer's USB port and gives you a full function numeric keypad and mouse. Lead length 700mm. $ $ Impervious to anything you can throw at it, having the highest rating for dust and water resistance. It performs all the normal mouse functions including scrolling and has a tactile rubber shell. Ideal for environments such as labs, factories, marine, military, science, food preparation etc. It can be cleaned with $ 95 water, alcohol, or disinfectant. Cat: XM-5139 39 • USB powered • IP68 rated 37 95 High performance 4-port hub with a difference: it has one port on top, so it's much easier to place a memory stick into. Data transfer of up to 480Mbps. • Plug and Play, no drivers needed, hot swappable • Compatible with Windows 98, 2000, Me, XP, Vista and Mac • Self-powered • Dimensions: 80(W) x 90(D) x 18(H)mm $ Note: Flash drive not included 7 port high speed hub also available (2 ports on the top) - simple, flexible and highly scalable connectivity solution. XC-4883 $59.95 Mini USB SD Card Reader 29 95 Cat: XC-4804 USB Wireless Rechargeable Optical Mouse With an ergonomic design to perfectly fit into your hand, an optical lens for precision aiming, and a rubber-like finish which prevents it slipping in your hand, this mouse stands out as a very modern piece of equipment. Relax and enjoy its features. • USB interface - Plug and Play • Compatible with Win 95/98/2000/NT/ME/XP Cat: XM-5138 $ 34 95 Cat: XM-5132 On-Line 1000VA 700W UPS SD cards are the most popular storage devices for digital cameras and just about every other device that uses portable storage. This low cost card reader has a SD slot on the side and is compact enough to take anywhere • USB 2.0 • Compact size • No drivers required $ 8 95 Cat: XC-4756 2.5/3.5" SATA HDD Dock with Card Reader A SATA Docking station loaded with features. Dock your 2.5 or 3.5 inch SATA HDD and it will instantly mount on your computer as an external hard drive. It also features slots for a multitude of cards. CF/SD/MS and their variations can all be read. It also has 2 USB ports. An invaluable tool for cloning disks or debugging HDD problems. Note: HD drive not included $ •Up to 480Mbps transfer rate with USB 2.0 •Up to 3Gb/s transfer rate with eSATA 4 Port High Performance USB Hub 79 95 Cat: XC-4692 This Industrial quality true online UPS is designed for critical loads. The UPS provides a perfectly clean sine wave output no matter what the mains throws at it. You’re covered for surges, spikes, noise, brownouts and blackouts for as long as the batteries last. A backlit LCD shows you the operating status and advises you of any fault condition. It also provides an RS-232 interface so the UPS can be connected to a computer and used with the included management software. See Website for full specifications $ 749 • Pure sine wave output Cat: MP-5210 • True on-line operation • 2 x 240V outlets • Software included DIY Kits 240V 10A Deluxe Motor Speed Controller Kit School Zone Speed Alert Kit This deluxe kit provides full speed control from near zero to maximum RPM, good speed regulation under load, very smooth low speed operation and is rated for devices up to 2300W. It also has soft-start to eliminate the kick from larger power tools and has interference suppression filtering, fuse protection and over-current protection with limiting. Basically a specialised timer that alerts you with a flashing LED when school zone-reduced speeds are in force. The unit will flash for the whole time the restrictions operate in the morning and afternoon. The kit includes all specified components, double-sided PCB and case with machined and screen-printed lid. Refer: Silicon Chip Magazine April 2009 $ • Overlay PCB & all components • Machined case included 99 95 Cat: KC-5478 Headlight Reminder For Cars Refer: Silicon Chip Magazine August 2001 Nothing is more frustrating than getting into your car early in the morning, only to discover that you had left your headlights on the night before, running your car’s battery flat. Features include a modulated alarm, ignition and lights monitoring, optional door switch detection, time-out alarm and a short delay before the alarm sounds. Build and install this hassle-saving kit and enjoy a feature in $ 95 your car that many luxury vehicle owners have long taken for granted. Cat: KC-5317 27 Refer: Silicon Chip Magazine April 2009 $ 49 95 Cat: KC-5472 Battery Zapper MkIII Refer: Silicon Chip Magazine July 2009 The popular battery zapper kit has gone through a couple of upgrades and this is the latest easier-tobuild version. Like the original project from 2005, it attacks a common cause of failure in lead acid* batteries: sulphation, which can send a battery to an early grave. The circuit produces short bursts of high levels of energy to reverse the sulphation effect. The battery condition checker is no longer included and the circuit has been updated and revamped to provide more reliable, long-term operation. It still includes test points for a DMM and binding posts for a battery charger. * Not recommended for use with gel batteries. • PCB with solder mask, overlay and components • Screen printed machined case • 6, 12 & 24VDC Free Call: 1800 022 888 for orders! www.jaycar.com.au $ 79 95 Cat: KC-5479 7 S e c u r i t y & S u rv e i l l a n c e 4 Zone Security Alarm System with 2 Wire Technology Rapport CCTV Field Tester Supplied with • Main control unit • Two PIRs • Four door or window contact switches • External swtich • 240VAC Adaptor • 50m two-core flat wire clips • Screw/wall plugs • Main unit: 160(H) x180(W) x35(D)mm • Extra PIR to suit LA-5476 $29.95 • Rechargeable Li-Po battery • CCTV video monitor • Video signal generator • Digital multimeter This alarm is so simple DIY enthusiasts will love it! All system components (sensors, sirens) are connected to the control unit via a two core flat wire. The unit has a built- in keypad with status LED and three modes of operation (Home, Out, Off). All sensors and sounders are line protected so any attempt to interfere will sound the alarm. $ 149 Cat: LA-5475 Hands Free Colour Video Door Phone Who’s at the door? With this video door phone you can view and talk to guests before letting them in or sound an alarm to turn away unwanted visitors. The camera can also be used at night thanks to its CCD sensor and infrared illumination. You can even hook up one additional monitor and camera to make a comprehensive front & back door personal surveillance system. $ • 7" TFT screen • AV output • AV input • Mains powered • Remote door release output 449 $ • MPEG-4 compression • 250GB HDD included 649 999 Cat: QM-3823 Multimeter specifications: • Dimensions: 88(W) 125(H) x 40(D)mm Mini Dome Dummy Camera This dummy dome camera looks exactly like the real thing at a fraction of the price. Make your business/home/office look like it's under surveillance. It even includes a metal camera casing inside, although it has no lens.. $ • Dimensions: 88mm(dia) x 68mm(H)mm 12 95 Cat: LA-5317 4 Channel DVR Camera Surveillance Kit This is an excellent DVR that is ideally suited to smaller surveillance installations around the home or office. It uses MJPEG video compression and can store over 150 hours of video on its 250GB hard drive. Recording setup is simple and various trigger modes can be set across the day including include timer recording, motion detection, and manual operation. YOUR LOCAL JAYCAR STORE 6788 4699 2822 9669 3899 4130 7155 3433 4799 6221 3100 3799 8337 3121 1614 7033 Tweed Heads Wollongong VICTORIA Cheltenham Coburg Frankston Geelong Hallam Melbourne Ringwood Springvale Sunshine Thomastown QUEENSLAND Aspley Caboolture Cairns Ipswich Mackay • DVR with 250GB HDD, 4 camera inputs, USB port, and 1 x composite video output • 4 x weather resistant COLOUR day/night cameras • Plug-in interconnection cables $ • Wireless remote control • Mains adaptor • User manual Cat: QV-3063 649 • See website for full specification. Cat: QV-3079 Australia Freecall Orders: Ph 1800 022 888 8 $ The system comes complete with: A combined multiplexer and digital video recorder with Ethernet port that allows control via a web browser. Features MPEG-4 compression, advanced motion recording, video loss detection, remote network record and back-up support. Supplied with a 250GB HD and can be expanded up to 400GB. See website for specifications. 340mm wide. 6021 9699 9709 9678 9369 9905 4620 4365 9439 9476 9821 4965 4721 8832 9267 9531 Specifications: • Input voltage: 12VDC • Charging time: 6 hours Cat: QC-3615 Economy 4 Channel Multiplexing DVR NEW SOUTH WALES Albury Ph (02) Alexandria Ph (02) Bankstown Ph (02) Blacktown Ph (02) Bondi Junction Ph (02) Brookvale Ph (02) Campbelltown Ph (02) Erina Ph (02) Gore Hill Ph (02) Hornsby Ph (02) Liverpool Ph (02) Newcastle Ph (02) Penrith Ph (02) Rydalmere Ph (02) Sydney City Ph (02) Taren Point Ph (02) Designed with portability and the professional CCTV engineer in mind, this is an advanced piece of test equipment with a variety of functions. As well as performing multimeter functions, it will test the quality of a video image signal and display it on the 3.5" LCD. Ph (07) 5524 6566 Ph (02) 4226 7089 Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph (03) (03) (03) (03) (03) (03) (03) (03) (03) (03) 9585 9384 9781 5221 9796 9663 9870 9547 9310 9465 5011 1811 4100 5800 4577 2030 9053 1022 8066 3333 Ph Ph Ph Ph Ph (07) (07) (07) (07) (07) 3863 5432 4041 3282 4953 0099 3152 6747 5800 0611 Maroochydore Ph (07) 5479 3511 Mermaid Beach Ph (07) 5526 6722 Townsville Ph (07) 4772 5022 Underwood Ph (07) 3841 4888 Woolloongabba Ph (07) 3393 0777 AUSTRALIAN CAPITAL TERRITORY Belconnen Ph (02) 6253 5700 Fyshwick Ph (02) 6239 1801 TASMANIA Hobart Ph (03) 6272 9955 Launceston Ph (03) 6334 2777 SOUTH AUSTRALIA Adelaide Ph (08) 8231 7355 Clovelly Park Ph (08) 8276 6901 Gepps Cross Ph (08) 8262 3200 WESTERN AUSTRALIA Maddington Ph (08) 9493 4300 Midland Ph (08) 9250 8200 Northbridge Ph (08) 9328 8252 Rockingham Ph (08) 9592 8000 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph (03) 379 1662 Dunedin Ph (03) 471 7934 Glenfield Ph (09) 444 4628 Hamilton Ph (07) 846 0177 Hastings Ph (06) 876 0239 Manukau Ph (09) 263 6241 Newmarket Ph (09) 377 6421 Palmerston Nth Ph (06) 353 8246 Wellington Ph (04) 801 9005 Freecall Orders Ph 0800 452 922 Prices valid to 23rd July ‘09 Free Call: 1800 022 888 for orders! www.jaycar.com.au PRODUCT SHOWCASE Waterproof ABS case from Jaycar You could buy a cheaper case for your compact camera, test gear, medical equipment, etc, at the local bargain store – but would you? It certainly won’t offer your gear much in the way of protection, especially if it gets wet. This new 260 x 94 x 159mm (external) case from Jaycar is made from tough ABS and is ideal for transporting sensitive equipment. It will protect valuable items from transit damage, dust and water ingress. The clam-shell style box has a soft “pluck” foam insert with precut squares that can be removed to snugly fit the item you want to protect. Its lid is also lined with egg shell foam, and is secured with strong ‘snap closed’ fasteners with a gasket seal that is waterproof and dustproof when closed. The case has a carry handle and two moulded anchor points that can be used for attaching tamper seals or padlocks. It will also float in case you’re unfortunate enough to drop your gear in the drink. It also comes in any colour you want, as long as it’s black. Ideal for cameras, test and measurement equipment, medical equipment etc, the usable internal dimensions Contact: Jaycar Electronics (all stores) are 239 x 94 x 159mm (w x h x d). You will be hard pressed to find a better PO Box 107, Rydalmere NSW 2116 case, even at twice the price – which, inci- Order Tel: 1800 022 888 Fax: (02) 8832 3188 Website: www.jaycar.com.au dentally is $49.95 (rrp). Cutter’s IP modem replaces analog and ISDN modems The SSV IGW/920-IPM from Cutter Electronics offers the ability to replace conventional modems with an IP-based intranet or Internet connection. The 10/100 Mbps LAN interface of the IGW/920-IPM is used for the connection to the IP network. The serial RS232 interface of the IGW/920-IPM emulates an AT command interpreter. The IP address of the other IP modem in each case serves as the phone number for the connection setup. Alternatively, a DNS name or phonebook entry (quick dialing via match table) can be used. Contact: The IGW/920-IPM is easy to set up using Cutter Electronics Pty Ltd the integrated browser interface. For this an Unit 12, 137-145 Rooks Rd, Vermont, Vic 3131 Ethernet LANbased connection to a PC with Tel: (03) 9873 5088 Fax: (03) 9873 5099 web browser will be established. Website: www.cutter.com.au Another PA labour-saver from Altronics Here’s one to bring a gleam to the eye of anyone who’s had to install a lot of PA or fire warning ceiling speakers: Altronic Distributors new Redback One-Shot, a ceiling-mounted speaker complete with its own mounting kit and grille. Instead of the usual four fixing screws, four cap covers and a lot of labour, this requires no fixings, fits in around four seconds and looks superb. Simply cut the hole in the 10-13mm thick ceiling (Altronics have the right size holesaw!), connect the speaker wires to the integral terminal block then push in the Contact: spring-loaded catches. The job is done! The model shown is a C-2146C 100V Altronic Distributors Pty Ltd 5W PA speaker which retails for $31.10 inc PO Box 8350, Perth Busn Centre, WA 6849 GST; 8 15W and Fire Evac models are also Tel: 1300 780 999 Fax: 1300 790 999 Website: www.altronics.com.au available. siliconchip.com.au Farnell’s new online technical training service In recognition of the increasing complexity of electronic solutions, Farnell has launched TechCast, a new online technical training service. It provides assistance and answers to customers seeking to understand the latest technology and obtain guidance in the selection of the most appropriate components for their designs. Techcast modules provide detailed information about a wide and diverse range of electronics technologies in a single, easy-to-use location. Accessed by a single click from the Farnell website homepage, TechCast online training modules are adopted from suppliers and placed in standard format to ease familiarity. Constantly added to, the library currently contains over 100 modules from 31 suppliers, such as Cree, Freescale, Molex and Murata Power Solutions, providing information on devices and products ranging from FPGAs and Microprocessors, to LEDs, connectors and front-end power supplies. An alphabetical search feature helps to speed up locating the required training module and users can select either narrated or silent formats. Adjacent to each training module indexed in the library is a ‘Parts List’ button which provides direct access to full technical and purchasing details for products referred to, or relevant to, that specific TechCast module. With a single click customers can then purchase products for same-day despatch across Australia and New Zealand with no minimum order sizes. TechCast complements other service initiatives recently introduced by Farnell, aimed at providing industryleading support to design engineers across the globe. These include the i-Buy free eprocurement management system and Live SC Technical Chat. Contact: Farnell 72 Ferndell St, Chester Hill NSW 2162 Tel: 1300 361 005 Fax: 1300 361 225 Website: www.farnell.com.au July 2009  57 Multi-Function Active Filter Module Versatile design can be configured as a low-pass, high-pass or bandpass filter just by moving a few jumper links By JOHN CLARKE This versatile Active Filter is ideal for use as an active crossover in loudspeaker systems but has lots of other uses as well. It can be configured as a low-pass filter (for driving sub-woofer amplifiers), as a high-pass filter or as a bandpass filter, simply by moving a few on-board jumper links. A CTIVE FILTERS ARE used in many analog circuits to tailor the frequency response. For example, an active filter could be used to prevent signals below 20Hz from passing through to the next stage (eg, to an amplifier). In this case, the filter allows the higher audio frequencies to pass through but blocks the sub-audio signals (including DC). This type of filter is called a “highpass” (HP) filter. If a HP filter is incorporated into an audio amplifier, it will prevent the woofer in a loudspeaker system from being driven at very low frequencies. In fact, it could be used as a turntable rumble filter to follow a 58  Silicon Chip magnetic cartridge preamplifier. Preventing a loudspeaker from being driven at very low frequencies is important because such frequencies would cause audible distortion in the sound due to excessive cone movement. In addition, excessive cone movement at or below the loudspeaker’s resonance frequency could damage the loudspeaker. Similarly, an active filter could also be used to limit signals above 20kHz. This will prevent supersonic signals from driving the loudspeaker and protect the tweeter(s) from damage. This type of filter is called a low-pass (LP) filter; it allows frequencies below a certain frequency to pass through but blocks higher frequencies. Bandpass filter Cascading a high-pass filter and a low-pass filter produces a bandpass filter. So if a 20Hz high-pass filter and a 20kHz low-pass filter are cascaded, we end up with a bandpass ranging from 20Hz to 20kHz. This means that the signal is attenuated both below 20Hz and above 20kHz, while those frequencies between 20Hz and 20kHz are basically left un-attenuated. However, some attenuation (or re­ duction) in level does occur as the signal frequency approaches 20Hz siliconchip.com.au PASSIVE FILTERS ACTIVE FILTERS TWEETER HP PREAMPLIFIER SIGNAL MIDRANGE BP TWEETER HP (HIGH PASS) AMPLIFIER AMPLIFIER AMPLIFIER SIGNAL MIDRANGE BP (BAND PASS) AMPLIFIER WOOFER LP (USUALLY IN LOUDSPEAKER ENCLOSURE) Fig.1: a single power amplifier is usually used to drive a passive crossover network in a loudspeaker box. and 20kHz, ie, the so-called corner or “roll-off” frequencies. Additional filters can also be used to split the 20Hz-20kHz audio frequency range into separate frequency ranges or bands. This might be done to produce a 2-way or 3-way active crossover for two or three drivers in a loudspeaker system. In greater detail, many loudspeaker systems include woofer, mid-range and tweeter drivers in the same box – see Fig.1. This is called a 3-way system, while a 2-way system includes just a woofer and a tweeter. The separate drivers are used because no single driver can faithfully reproduce the whole audible range from 20Hz to 20kHz. So the audio band of frequencies is divided up and each driver is fed with its own “ideal” range of frequencies. In a 3-way system, for example, the woofer could be provided with signals ranging from 20Hz to say 150Hz, while the midrange would handle signals ranging from 150Hz to 2kHz. The tweeter would then cover the remainder of the audio range, ie, from 2-20kHz. Passive crossovers In most loudspeaker systems, the incoming audio signal is divided into separate frequency bands using passive filters. These “crossover filters” are located inside the loudspeaker box itself and are made up using inductors, capacitors and resistors. Basically, a well-designed crossover network gives outputs to match the particular drivers used. This ensures that each driver (ie, woofer, mid-range and tweeter) is fed only with a frequency band it can effectively reproduce. siliconchip.com.au WOOFER LP (LOW PASS) Fig.2: the arrangement for an active crossover filter system. The filters go before the power amplifiers and a separate amplifier is required for each loudspeaker driver. In addition, the design must cater for drivers that have different sensitivities and set the signal levels to achieve an overall flat frequency response. For example, the woofer is often less sensitive than the midrange driver and tweeter and so the signals to the latter drivers must be reduced so that the output levels from the three drivers are well matched. This does waste amplifier power, however. Another problem to contend with is non-linearity in the driver impedances and so extra components are often used in the crossover network to correct this, so that the filter appears to drive a purely resistive load. As a result, the crossover networks in highperformance speaker systems are often complex and can be difficult to design and optimise. They also interpose a complex RLC network between the amplifier and the speakers which can mean a loss of damping factor. That particularly affects the lower frequencies where a high damping factor is most needed to achieve tight, clean bass and midrange reproduction. As shown in Fig.1, a single power amplifier usually drives the passive crossover network in a loudspeaker system. However, some loudspeaker systems provide additional connections so that each driver can either be driven independently by its own amplifier (via its passive filter) or by a single amplifier but with separate wiring to each passive filter section. Active crossovers Active crossovers are an alternative to passive filtering. However, for this to work, a separate amplifier is required for each driver – see Fig.2. For a stereo system, that means six power amplifiers (or three stereo amplifiers) to drive 3-way loudspeakers or four amplifiers for 2-way loudspeakers. As shown in Fig.2, the crossover filtering is now placed ahead of each amplifier to set the frequency band Specifications Voltage Gain: adjustable from 0-2; typically set at 1 Frequency Response: filter dependent Filter Attenuation slope: 24dB/octave or 80dB/decade Total Harmonic Distortion: typically .003% at 1V RMS Signal-to-Noise Ratio: >100dB with respect to 1V input and 22Hz to 22kHz unweighted Input Impedance: 47kΩ Supply Voltage: ±15V to ± 60V DC dual rail supply or +12-30V DC single rail supply or 11-43VAC Current Consumption: 40mA maximum July 2009  59 FILTERS SELECTION MATRIX INPUT BUFFER INPUT HPin HP IC2b LPout IN x1 HP IC2a LEVEL OUT HPout IC1a OUTPUT AMPLIFIER x2 LPin FILTERS LP IC3a VR1 OUTPUT IC1b LP IC3b Fig.3: block diagram of the Multi-Function Active Filter. The low-pass and high-pass filter stages each consist of two cascaded op amps and the unit is configured by installing jumper links on the pins of the “selection matrix”. applied to its driver. There are two advantages to this scheme: (1) better control of the driver and (2) the inductive load presented by the driver does not affect the filter response (as it does in a passive system). So our Multi-Function Active Filter module is designed to be used ahead of each amplifier. Basically, you need to build and configure one module for each driver (and amplifier) in the system. For a woofer, the module would be configured as a low-pass (LP) filter, while a bandpass (BP) filter would be used ahead of the mid-range amplifier. The tweeter driver amplifier would have a high-pass (HP) filter ahead of it. Supply options In operation, the Multi-Function Active Filter would typically be powered from the supply rails of the amplifier. Options are available to power the module from supply rails ranging from ±60V down to ±15V or from an 11-43V AC source. AMPLITUDE CUTOFF ROLLOFF SLOPE TRANSITION BAND A HIGH PASS (HP) Block diagram Fig.3 shows the block diagram of the Multi-Function Active Filter (minus the power supply). It uses an input buffer stage (IC1a), four op amps to form the filter stages (IC2a,b & IC3a,b) and an output amplifier stage (IC1b) IC1a is configured with a gain of one and can be connected to drive either the HP or LP filter stages, depending on the jumper options on the PASS BAND FREQUENCY Rolloff slope Note that the signal is not fully attenuated at the cutoff points but instead gradually decreases at a rate determined by the rolloff slope. In this case, each 2-pole filter stage has a rolloff of 40dB per decade or 12dB per octave. However, because the filter stages are cascaded, this rolloff increases to 80dB per decade or 24dB per octave and the signal level is actually 6dB down at the cutoff (crossover) points. For a high-pass filter, the output from IC2b is fed through to level con- HIGH PASS CUTOFF CUTOFF PASS BAND STOP BAND The Multi-Function Active Filter can also be powered from a single supply rail, such as +25V, +15V or +12V. The 12V option enables it to be used in cars. On-board jumper links are used to configure the module for LP, BP or HP operation. The roll-off frequencies are set by selecting the appropriate resistor and capacitor values in the filter feedback networks. These filter component calculations are made easy by using freely available software from the Internet. “Selection Matrix” block. If we want a HP filter, then terminal “IN” is connected to “HPin” on the matrix block. Alternatively, for an LP filter, “IN” is connected to terminal “LPin”. As shown, the high-pass filter uses two 2-pole HP filters based on IC2a & IC2b. These are connected in series (or “cascaded”). Similarly, the low-pass filter stage consists of 2-pole LP filters IC3a & IC3b. Fig.4a shows the response for a HP filter and the way the filter response is described. As indicated, the region where frequencies pass through unattenuated is called the passband. Below the cutoff frequency, the response begins to rolloff (or is reduced) in level. This rolloff region is called the stopband. An LP filter is similar except that it allows low-frequency signals to pass through and blocks signals above the cutoff point (Fig.4b). Finally, the bandpass filter rolls off both the low and high-frequency signals and the pass band is between the high-pass and low-pass cutoff frequencies (Fig.4c). ROLLOFF SLOPE ROLLOFF SLOPE LOW PASS CUTOFF PASS BAND ROLLOFF SLOPE STOP BAND TRANSITION BAND B LOW PASS (LP) C BAND PASS (BP) Fig.4: the high-pass filter (A), low-pass filter (B) and bandpass filter (C) response characteristics. Because the op amp filter stages are cascaded, the rolloff slope in each case is 24dB per octave and the signal is actually 6dB down at the cutoff (crossover) points. 60  Silicon Chip siliconchip.com.au Parts List Amplifiers For Active Crossover Systems T HE AUDIO AMPLIFIER requirements for active crossover loudspeaker systems depend on the power hand­ ling rating for each loudspeaker. Typically, a woofer (or subwoofer) amplifier should have twice the power of the midrange and treble amplifiers. For example, a 100W power amplifier could be used for the woofer, and 50W amplifiers used for the midrange and treble drivers. One problem is that the output from a preamplifier will only have a single RCA output for each left and right channel. However, you will need to connect the preamp signal to two or three active filters, depending on how many drivers are in the loudspeaker. This problem is easily overcome by using an RCA Plug to 2 x RCA Socket such as the Jaycar Cat. PA-3560. Two such adaptors will be required for each channel if you want to drive three active filter modules (ie, if you have a 3-way loudspeaker system). Alternatively, you could use RCA plug-to-plug leads with piggyback RCA sockets (eg, Jaycar WA-7090/1/2/3 or Altronics P-7260) or you could make up your own 2-way or 3-way RCA socket panels. trol VR1 by connecting point “HPout” to “OUT” in the selection matrix. Alternatively, for a low-pass filter, the output of IC3b at “LPout” is connected to the “OUT” terminal. Bandpass filter connections Bandpass filtering is achieved by cascading the high-pass and low-pass filter stages, ie, by connecting the output of the high-pass stages to the input of the low-pass stages or vice versa. However, it is normal to feed the signal to a HP filter first and then use this to drive the LP filter, rather than placing the LP filter first. This will result in less noise due to the final low-pass filtering. However, you can connect the LP filters first if that’s what you want to do. Normally, to configure a bandpass filter, the signal is first fed to HP filter stage IC2a by linking “IN” to “HPin”. The output from IC2b is then fed to the input of low-pass stage IC3a by connecting “HPout” to “LPin” in the Selection Matrix. The resulting bandsiliconchip.com.au pass filtered signal at the output of IC3b is then fed to VR1 by connecting “LPout” to “OUT”. Level control The signal on VR1’s wiper is fed to IC1b. This is configured as a noninverting amplifier with a gain of two. As a result, VR1 can be adjusted to vary the signal at its output between zero and x2. This level adjustment allow the sound levels from the woofer, midrange and tweeter drivers to be adjusted when multiple filter modules are used. By the way, the recommended design for each 2-pole stage is for a Butterworth response. When connected in series, the result of cascading two Butterworth filters is a Linkwitz-Riley (L-R) response. This is ideal because at the crossover region, where one filter takes over from another, the overall L-R frequency response is flat. Note that the HP and LP filters must be set for same crossover frequency for this to happen. 1 UB3 plastic utility case 130 x 68 x 44mm (optional) 1 PC board, code 01107091, 123 x 63mm 1 3-way PC-mount screw terminal block with 5.08mm pin spacing (CON1) 4 DIP8 IC sockets 1 3-way DIL pin header with 2.54mm pin spacings 2 3-way SIL pin header with 2.54mm pin spacings 5 jumper plugs to suit pin headers 1 100mm length of 0.8mm tinned copper wire or four 0Ω links 4 PC stakes Semiconductors 3 LM833 dual op amps (IC1-IC3) 1 TL071, LF351 single op amp (IC4) 2 1N4744 15V 1W zener diodes (ZD1,ZD2) 2 1N4004 1A 400V diodes (D1,D2) Capacitors 2 470µF 16V PC electrolytic 1 100µF 16V PC electrolytic 2 4.7µF non-polarised (NP) electrolytic 2 100nF MKT polyester 1 10nF MKT polyester 1 220pF ceramic C1,C2,C3 to suit application (use MKT polyester) (see text & tables) Resistors (0.25W, 1%) 1 47kΩ 2 150Ω 4 10kΩ 3 10Ω Ra, Rb, R1, R2 & R3 to suit power supply & filter type (use 1% 0.25W for R1, R2 & R3) (see text & tables) As indicated previously, the MultiFunction Active Filter board can only produce a single LP, HP or BP filter output. This means that it can only provide signal to one loudspeaker driver – it is not designed to provide for two (or more) outputs. This in turn means that if you want separate LP, BP and HP filter outputs, then three Multi-Function Active Filter modules must be built (or six for a stereo system). Basically, a different filter is required for each amplifier and it can be installed inside its associated amplifier’s case. July 2009  61 Fig.5: this screen grab shows the frequency response for the low-pass filter configuration with a nominal corner frequency of 1kHz. The attenuation slope is 24dB per octave. arrangement. This was used in preference to the unity gain Sallen-Key style of filter because the MFB response is less affected by component value variations due to manufacturing tolerances. Note that 10Ω stopper resistors are included in series with the HP filter inputs. This is done in each case to prevent instability (oscillation) in the preceding stage. IC2a’s output is fed to the second HP filter stage IC2b (ie, the stages are cascaded), while IC3a drives the second LP filter stage IC3b. For a HP filter, IC2b’s output is fed to level potentiometer VR1 by linking “HPout” to “OUT” in the Selection Matrix. Alternatively, for a LP filter, the output from IC3b is connected to level potentiometer VR1 using a jumper to link “LPout” to “OUT”. Again, this functions exactly as described for block diagram Fig.3. Finally, for a bandpass arrangement, HP filter IC2b’s output is fed to LP filter IC3a via a jumper link between “HPout” and “LPin”. IC3b’s output is then fed to VR1 level via a jumper link between “LPout” and “Out”. Minimising noise Fig.6: the frequency response for a high-pass filter configuration with a nominal corner frequency of 1kHz. Once again, the attenuation slope is 24dB per octave. The inputs of the various active filter modules are then all driven in parallel by the preamplifier. Circuit details OK, let’s now take a look at the full circuit details – see Fig.7. It comprises three dual op amps (IC1-IC3) plus a single op amp (IC4) in the power supply section. The first thing to note here is that the designations for the op amps used in the input buffer, filter and output stages match those shown on the block diagram of Fig.3. So if you’ve followed the description for Fig.3, understanding how the full circuit works should be a snack. As shown, the incoming audio signal is applied to unity gain buffer 62  Silicon Chip stage IC1a via a 4.7µF non-polarised capacitor and a 10Ω stopper resistor. The capacitor is there to block any DC voltage, while the stopper resistor blocks any stray RF signals that may have been picked up by the leads. IC1a is biased to Earth 2 via the associated 47kΩ resistor. This earth is at 0V for plus and minus supply rails and at half-supply (0.5Vcc) for a single supply. IC1a’s output is fed to either HP filter IC2a or to LP filter IC3a, depending on the input jumper location in the Selection Matrix. This works exactly as indicated previously in the description for the block diagram (Fig.3). Both the high-pass and low-pass filter stages (IC2a, IC2b, IC3a & IC3b) use a multiple feedback (MFB) 2-pole As stated earlier, the signal from IC1a is normally fed to the HP filter stages first (“IN” linked to “HPin”), so that the LP filter stages can then minimise noise. Alternatively, the LP stages can be placed first by linking “IN” to “LPin”, “LPout” to “HPin” and “HPout” to “OUT”. The resulting audio signal on VR1’s wiper is fed directly to the non-inverting input (pin 5) of IC1b. As previously stated, this amplifier has a gain of 2 but this gain reduces to 1 for frequencies above 72kHz due to the 220pF capacitor across the feedback resistor. IC1b’s output appears at pin 7 and is coupled to the output terminals via a 150Ω isolating resistor and a 4.7µF NP (non-polarised) capacitor and 150Ω isolating resistor. Power Supply In operation, the Multi-Function Active Filter would typically be powered from the supply rails of the amplifier. As stated previously, options are available to power the module from dual DC supply rails or from an AC source. The unit can also be powered from a single supply rail, such as +25V, +15V or +12V. The 12V option enables it to be used in a car. siliconchip.com.au siliconchip.com.au July 2009  63 47k 10 K 2 3 A V– 4 IC1a 8 ZD2 15V 1W INPUT BUFFER K D2 1N4004 A D1 1N4004 1 100nF K A LK1 10 1 2 LPin IN R1c HPout OUT SELECTION MATRIX HPin LPout 470 F 16V R3c C2c R2a C1a V– C3a ZD1 15V 1W MULTI-FUNCTION ACTIVE FILTER 4.7 F NP Rb Ra 3 2 3 2 R2c A K R1a LP FILTER IC3a C1c HP FILTER IC2a C2a 470 F 16V 1 1 10k 10k 10 R1d V– 2 C2d R3d R2b C1b 100 F 16V 3 A 8 4 8 7 HP FILTER 4 IC2b C1d IC3b 5 6 R1b 150 C2b 6 LP FILTER K D1, D2 5 6 R2d C3b 4 IC4 7 7 V– 100nF V+ A 6 5 10k K ZD1, ZD2 10k LEVEL VR1 EARTH 1 10nF EARTH 2 1 LK2 2 OUTPUT AMPLIFIER 10k 220pF IC1b V– V+ 7 8 4.7 F NP 1 IC1 – IC4 150 IC1 – IC3: LM833 IC4: TL071 Fig.7: the complete circuit for the Multi-Function Active Filter. IC1a serves as an input buffer stage while op amp IC1b is the output amplifier. Cascaded op amp stages IC2a & IC2b together form the high-pass filter, while IC3a & IC3b make up the low pass filter. IC4 is used to provide a half-supply reference if the unit is powered from a single-rail power supply. 2009 SC  INPUT – 0V + SUPPLY INPUT 4 OUTPUT ± SUPPLIES: LK1=1, LK2 =1 19070110 Rb D2 4004 HPout C2c C1c 1 100nF Table 1: Capacitor Codes Value µF Value IEC Code 100nF 0.1µF 100n 10nF 0.01µF   10n 220pF NA 220p EIA Code    104    103    221 150 C1d C2d Fig.8: follow this parts layout diagram to build the PC board. The various tables show the values for resistors Ra & Rb and for the filter components (R1-R3 & C1-C2), while the linking options for the selection matrix are shown at right. Links LK1 & LK2 go in position 1 for a dual-rail supply (or for an AC supply) but must be moved to position 2 for a single-rail supply. In summary, the three options for powering the module are as follows: (1) A dual-rail (plus & minus) supply of between ±15V and ±60V (this connects to the “+” and “-’ supply inputs of the terminal block); (2) A single DC supply rail ranging from 12-60V (this connects between the “+” and “0V” supply inputs); and (3) An AC supply ranging from 1243VAC (in this case, the “+” and “-” inputs are tied together and the AC supply is connected between these IN 220pF 10k EVIT CA LK1 10k 1 R1d 15V CON1 LPin VR1 GND 10k R1c 2 1 OUT NI HPin IN LPin TU O 4.7 F NP SIGNAL OUTPUT LPout OUT HPout LOW PASS FILTER commoned inputs and the 0V input). In the case of a dual supply, diodes D1 and D2 (1N4004) protect the circuit against reverse polarity connection. Zener diodes ZD1 and ZD2 then regulate the supply to provide ±15V rails which are then used to power op amps IC1-IC3. Two two 470µF capacitors decouple the ±15V supply rails. Resistors Ra & Rb are used to limit the current into ZD1 and ZD2. The values of these two resistors depend on the input voltage (see Table 4 for the required values). In addition, for a dual supply, Earth 1 and Earth 2 are connected together by installing jumper link LK2 in position 1 (LK1 must also be in position 1 or left out). With no signal, this sets op amps IC1, IC2 & IC3 so that their outputs sit at 0V. For a single supply, ICs1-3 need to GND OUT 2 IN R2d 470 F 1 100nF 47k HPin LPout LEVEL R3d 100 F 10nF IC3 LM833 10k ZD2 LK2 –– 150 V0 – 10k 1 IC4 TL072 SUPPLY 0V INPUT 470 F R2c + R3c + C3b C2b IC1 LM833 C2a C3a 15V SIGNAL INPUT 4.7 F NP 10 1 IC2 LM833 RETLIF R1a R2a 10 Ra ZD1 C1b 10 C1a R2b 4004 R1b D1 SINGLE SUPPLY: LK1=2, LK2 = 2 HPin IN LPin LPout OUT HPout HIGH PASS FILTER HPin IN LPin LPout OUT HPout BANDPASS FILTER be biased at half-supply so that the signal can swing symmetrically without clipping. This half-supply rail is provided by op amp IC4. As shown, a half-supply voltage is derived using two 10kΩ resistors in series across the positive supply rail. This is decoupled by a 100µF capacitor and then buffered by IC4 to drive Earth 2 when LK2 is in the “2” position. In addition, for a single supply, the negative supply pins for ICs1-3 are connected to the 0V supply rail by placing link LK1 in position 2. Note that when LK2 is in position 2, the half-supply output from IC4 is bypassed to earth (0V) via a 10nF capacitor. This prevents oscillation in the filter op amps. The 150Ω resistor at pin 6 of IC4 isolates the op amp’s output from the capacitance in the shielded output leads. Table 2: Resistor Colour Codes o o o o o o o o o o o No.   1   1   1   1   4   2   2   2   2   3 64  Silicon Chip Value 47kΩ 15kΩ 13kΩ 12kΩ 10kΩ 6.2kΩ 5.6kΩ 4.7kΩ 150Ω 10Ω 4-Band Code (1%) yellow violet orange brown brown green orange brown brown orange orange brown brown red orange brown brown black orange brown blue red red brown green blue red brown yellow violet red brown brown green brown brown brown black black brown 5-Band Code (1%) yellow violet black red brown brown green black red brown brown orange black red brown brown red black red brown brown black black red brown blue red black brown brown green blue black brown brown yellow violet black brown brown brown green black black brown brown black black gold brown siliconchip.com.au into RF? There’s something to suit every radio frequency fan in the SILICON CHIP reference bookshop RF Circuit Design – by Chris Bowick A new edition of this classic RF design text - tells how to design and integrate RF components into virtually any circuitry. $ 75 Practical RF H’book – by Ian Hickman A reference work for technicians, engineers, students and the more specialised enthusiast. Covers all the key topics in RF that you $ need to understand 90 Table 3: Filter Type Configuration Low-Pass Filter Link IN to LPin; Link LPout to OUT High-Pass Filter Link IN to HPin; Link HPout to OUT Bandpass Filter Link IN to HPin; Link HPout to LPin; Link LPout to OUT Table 4: Power Supply Configuration Input Voltage ±60VDC, 43VAC ±55VDC, 40VAC ±50VDC, 35VAC ±45VDC, 30VAC ±40VDC, 28VAC ±35VDC, 25VAC ±30VDC, 20VAC ±25VDC, 18VAC ±20VDC, 15VAC ±15VDC, 11VAC +30V +25V +20V +15V +12V Ra 1.2kΩ 5W 1kΩ 5W 820Ω 5W 680Ω 5W 560Ω 5W 470Ω 5W 390Ω 5W 270Ω 5W 120Ω 1W 10Ω 0.5W 390Ω 5W 270Ω 5W 120Ω 1W 10Ω 1/2W 10Ω 1/2W Rb 1.2kΩ 5W 1kΩ 5W 820Ω 5W 680Ω 5W 560Ω 5W 470Ω 5W 390Ω 5W 270Ω 5W 120Ω 1W 10Ω 0.5W NA NA NA NA NA Finally, for an AC supply, D1 & D2 function as half-wave rectifiers to derive positive and negative supply rails. The circuit then functions exactly the same as for a dual-rail DC supply. Construction All parts for the Multi-Function Active Filter are mounted on a PC board coded 01107091 and measuring 123 x 63mm. This can either be housed inside a UB3 plastic utility case measuring 130 x 68 x 44mm or installed within an amplifier case. siliconchip.com.au Links LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 1, LK2 position 1 LK1 position 2, LK2 position 2 LK1 position 2, LK2 position 2 LK1 position 2, LK2 position 2 LK1 position 2, LK2 position 2 LK1 position 2, LK2 position 2 Note that corner cutouts will be required if mounting the board in a utility case, to clear the integral mounting posts. Fig.8 shows the parts layout on the PC board. However, before starting the assembly, you have to decide on the power supply to be used, the type of filter arrangement and the cutoff frequency. Table 4 shows the resistors (Ra & Rb) required for various power supply voltages, plus the LK1 & LK2 linking options. The filter component values Practical Guide To Satellite TV – by Garry Cratt The reference written by an Aussie for Aussie conditions.Everything you need to know. $ 49 You’ll find many more technical titles in the SILICON CHIP reference bookshop – see elsewhere in this issue into ? S O R C I M There’s something to suit every microcontroller maestro in the SILICON CHIP reference bookshop Microcontroller LNEW W Projects in C wPRO IC as $ E! – by Dogan Ibrahim 81 Graded projects introduce microelectronics, the 8051 and programming in C. $ 60 Hands-On Zigbee – by Fred Eady An in-depth look at the clever little chip that’s starting to be found in a wide range of equipment from consumer to 50 $ industrial. 96 Programming 16-Bit Microcontrollers in C – by Luci Di Jasio Learning to fly the PIC24. Includes a CD ROM with source code in C, Microchip C30 complier $ and MPLAB SIM. 90 You’ll find many more technical titles in the SILICON CHIP reference bookshop – see elsewhere in this issue July 2009  65 Using The FilterPro Software From TI Fig.9: this is how FilterPro should look when set up to calculate values for a low-pass 2-pole Butterworth filter. The first step here is to download the 2.848MB zipped file (available from http: //focus.ti.com/docs/toolsw/folders/print/ filterpro.html) and run the FilterPro­Setup. exe file. That done, navigate to C:\ProgramFiles\Ti Analog Design Centre\Filterpro and create a shortcut on your desktop for FilterPro.exe. When you launch FilterPro, the program will show a screen with a graph, the filter circuit and various settings (see Fig.9). The graph shows the frequency response of the filter using an amplitude versus frequency plot. The actual rolloff can be seen as well as any excursions in the response across the passband or at the cutoff frequency. Calculating The Filter Component Values C HOOSING THE CROSSOVER FREQUENCIES for loudspeaker drivers requires careful consideration.You will need the data sheet for each driver in order to make a decision as to where the crossover frequency should lie. Ideally, the crossover frequency should be well away from the driver’s resonance frequency and the adjacent drivers should be a good match to ensure a smooth frequency response across the audio band. Many books have been written on the subject and a good reference is “The Loudspeaker Speaker Design Cookbook” by Vance Dickason. This is available from Jaycar, Cat. BA-1400. Once you have decided on the crossover frequencies, the filter component values can be calculated. Tables 5 and 6 show the recommended values for a range of common frequencies. For other frequencies, you can download software off the net to make the calculations easier. Our recommendation is to use “Filter Pro” from Texas Instruments. You can download it from http://focus.ti.com/docs/toolsw/ folders/print/filterpro.html If this site becomes unavailable, do a search for “Ti filter software” or for “FilterPro”. Information on how to use FilterPro and other useful information on filters is available at http://focus.ti.com/lit/an/sbfa001a/sbfa001a.pdf An alternative on-line program is also available from Okawa Electric – see the section entitled “Using the FilterPro Software From TI”. 66  Silicon Chip Two other responses are also shown on the graph: the phase response and the group delay. The phase response plots the phase variations in the filter output as a function of frequency. By contrast, the group delay shows the slope (or rate of change) in the phase response and is ideal for displaying the filter response to a pulse signal. Several different filter types can also be selected – ie, Bessel, Butterworth and Chebychev. Each has a different “Q” value and so the filter response differs from one to the other. Each filter type has its own advantages and disadvantages. For example, a Bessel filter has a Q of 0.577 (1/√3) and has a smooth but drooping amplitude response across the passband. It has very little pulse response overshoot and its rolloff is not as steep as for a Butterworth filter. Butterworth filters have a “Q” of 0.7071 (1/√2) and have the flattest possible (max­ imally flat) amplitude response in the passband and a moderate pulse response rise (or overshoot) at the cutoff frequency. A Chebychev filter has a higher Q again. This filter has ripple in the passband, a steeper cutoff rate and higher pulse response overshoot compared to the two lower Q filters. The Q value depends on the amount of ripple that can be tolerated and is 0.956 for a 1dB passband ripple and 0.863 for a 0.5dB passband ripple. A filter with a “Q” of 0.5 is critically damped and shows no pulse response overshoot. The Bessel, Butterworth and Chebychev filters are all under-damped and so each show some degree of overshoot in its response. An over-damped filter would have a “Q” of less than 0.5. Butterworth filters For audio work, the best compromise filter type is the Butterworth, especially when two filters are cascaded as in our Multi-Function Active Filter. So in FilterPro, select “Butter- are selected from Tables 5 & 6 (see also the panel titled “Calculating The Filter Component Values”). Note that for the single supply option, Rb, D2, ZD2 & C5 can be omitted. However, it does not matter if they are installed. Alternatively, for a dual rail supply option, IC4, R4, R5 & C6 are not required. Note also that either 5W or 0.5W resistors can be used for Ra & Rb, as the PC board accepts both types. For a LP filter only, there is no need to install the HP components. These siliconchip.com.au FilterPro provides values for the resistors and capacitors using R1, R2 & R3 and C1, C2 & C3 component designations. These are easily equated with the component designations on the circuit diagram (Fig.7) and parts layout diagram (Fig.7). Note: the a, b, c & d designations on Fig.7 are there simply to distinguish one filter circuit from another. Bandpass filter A bandpass filter is made by designing two separate cascaded HP and LP circuits. For example, if you want a bandpass filter with rolloffs at 500Hz and 2kHz, you simply use FilterPro to design independent 500Hz high-pass and 2kHz low-pass stages. Do not select a bandpass design in FilterPro – the calculations are not applicable to the Multi-Function Active Filter module described here. Alternative software worth” as the filter type and select “2” for the number of poles. The circuit type should be set to “MFB single ended” and the set display value should be “component values”. For components, select “E24” series for the resistors and either “E6” or “E12” for the capacitors (these “E” series values select the number of values available in a decade range). The relevant resistor and capacitor values will then be calculated based on readily available components. Note: some component suppliers may not have the full E12 capacitor series. In that case, a recalculation may have to be made using the E6 series instead if using the E12 series gives components values that are unavailable. The next step is to enter the cutoff frequency, select either LP or HP and then click on an unused section of the screen to start calculating the values. Note that the circuit for the multiple feedback 2-pole filter shows the values for a single 2-pole filter section. These same values are also used in the second 2-pole filter stage of the Multi-Function Active Filter. If you want to use an alternative program to FilterPro or if you want to check the predicted response of your filter using the values given by FilterPro, a good on-line program is one from Okawa Electric. For the low-pass filter, go to http://sim.okawa-denshi.jp/en/ OPtazyuLowkeisan.htm For the high-pass filter navigate to http://sim.okawa-denshi. jp/en/OPtazyuHikeisan.htm These sites not only allow you to calculate filter components but also allow you to input component values. The program will then show the actual cutoff frequency, filter Q and other features. These calculations can sometimes give a better result (ie, closer to the required Q and cutoff frequency) than FilterPro. Note, however, that the R1, R2, R3, C1, C2 & C3 labelling is a little different to that of the FilterPro and our circuit, so make sure you transpose the labelling correctly. Also, do not forget to tick the Q value field at 0.707 rather than using the ticked damping ratio field of 1 for the calculation. include IC2, R1a, R2a, C1a, C2a, C3a, R1b, R2b, C1b, C2b & C3b. The two 10Ω stopper resistors can also be left out (but not the one on pin 3 of IC1a). Similarly, for a HP filter, you can leave out LP components IC3, R1c, R2c, R3c, C1c, C2c, R1d, R2d, R3d, C1d & C2d. Start the assembly by carefully inspecting the board for any defects, then install the four wire links. Alternatively, 0Ω resistors can be used instead of the wire links. These look similar to a 0.25W resistor but have just one single black band around the centre of the body. Next, install four PC stakes at the input and output positions, then install the resistors and trimpot VR1. Table 2 shows the resistor colour codes but a digital multimeter should also be used to check values, just to make sure. Follow these with the diodes, zener diodes and the ICs. These parts must all be installed with the correct orientation. Note that IC4 is a different type to IC1, IC2 & IC3, so don’t get it mixed up. We used IC sockets for the ICs and these sockets also have an orientation notch at one end – see Fig.8. The electrolytic capacitors are next on the list and these must also be oriented correctly. The only exceptions here are the two 4.7µF NP (nonpolarised) types which can go in either way around. Once these parts are in, install the two 3-way SIL (Single In-Line) headers for links LK1 & LK2. The two jumpers Fig.10: the low-pass filter design software from Okawa Electric shows the circuit values and filter responses in a similar way to FilterPro. A high-pass filter design tool is also available from Okawa Electric – see text. siliconchip.com.au July 2009  67 Table 5: High-Pass Filter Component Values (Butterworth Response) Frequency C1 (IEC Code) (EIA Code) C2 (IEC Code) (EIA Code) C3 (IEC Code) (EIA Code) R1 R2 50Hz 100Hz 120Hz 150Hz 200Hz 300Hz 500Hz 1kHz 1.5kHz 2kHz 3kHz 5kHz 10kHz 20kHz 330nF (334) 150nF (154) 150nF (154) 100nF (104) 68nF (683) 47nF (473) 33nF (333) 15nF (153) 10nF (103) 6.8nF (6n8) (682) 6.8nF (6n8) (682) 3.3nF (3n3) (332) 1.5nF (1n5) (152) 680pF (681) 330nF (334) 150nF (154) 150nF (154) 100nF (104) 68nF (683) 47nF (473) 33nF (333) 15nF (153) 10nF (103) 6.8nF (6n8) (682) 6.8nF (6n8) (682) 3.3nF (3n3) (332) 1.5nF (1n5) (152) 680pF (681) 330nF (334) 150nF (154) 100nF (104) 100nF (104) 100nF (104) 68nF (683) 33nF (333) 15nF (153) 10nF (103) 10nF (103) 6.8nF (6n8) (682) 3.3nF (3n3) (332) 1.5nF (1n5) (152) 1nF (102) 20kΩ 22kΩ 24kΩ 22kΩ 20kΩ 20kΩ 20kΩ 22kΩ 22kΩ 20kΩ 20kΩ 20kΩ 22kΩ 20kΩ 4.3kΩ 5.1kΩ 4.7kΩ 5.1kΩ 4.7kΩ 4.7kΩ 4.3kΩ 5.1kΩ 5.1kΩ 4.7kΩ 4.7kΩ 4.3kΩ 5.1kΩ 4.7kΩ Table 6: Low-Pass Filter Component Values (Butterworth Response) Frequency R1 R2 R3 50Hz 100Hz 120Hz 150Hz 200Hz 300Hz 500Hz 1kHz 1.5kHz 2kHz 3kHz 5kHz 10kHz 20kHz 5.6kΩ 5.6kΩ 4.7kΩ 5.6kΩ 6.2kΩ 6.2kΩ 5.6kΩ 5.6kΩ 5.6kΩ 6.2kΩ 6.2kΩ 5.6kΩ 5.6kΩ 6.2kΩ 5.6kΩ 5.6kΩ 4.7kΩ 5.6kΩ 6.2kΩ 6.2kΩ 5.6kΩ 5.6kΩ 5.6kΩ 6.2kΩ 6.2kΩ 5.6kΩ 5.6kΩ 6.2kΩ 12kΩ 15kΩ 12kΩ 13kΩ 15kΩ 13kΩ 12kΩ 15kΩ 13kΩ 15kΩ 13kΩ 12kΩ 15kΩ 15kΩ C1 (IEC Code) (EIA Code) C2 (IEC Code) (EIA Code) 150n (154) 68nF (683) 68nF (683) 47nF (473) 33nF (33) 22nF (223) 15n (153) 6.8nF (6n8) (682) 4.7nF (4n7) (472) 3.3nF (3n3) (332) 2.2nF (2n2) (222) 1.5n (1n5) (152) 680pF (681) 330pF (331) 1µF (105) 470nF (474) 470nF (474) 330nF (334) 220nF (224) 150nF (154) 100nF (104) 47nF (473) 33nF (333) 22nF (223) 15nF (153) 10nF (103) 4.7nF (4n7) (472) 2.2nF (2n2) (222) Be sure to choose the correct filter component values when building the PC board – see Tables 5 & 6. In this case, the board has been configured as a highpass filter and is set up to accept dual supply rails. 68  Silicon Chip can then be fitted to these headers. They both go in position 1 for a dualrail supply (or if you are using an AC supply) – see Table 4. Alternatively, install them both in position 2 if you intend using a single rail supply. The selection matrix requires a 3-way DIL (Dual In-Line) pin header and this should now be installed – it goes in just to the left of trimpot VR1. Once it’s in, install the jumpers on this header to select your filter type (ie, LP, HP or bandpass). The assembly can now be completed by installing the 3-way screw terminal block. Power supply checks Before applying power, check that the supply link options are correct (see Table 4) and that the correct values have been installed for resistors Ra & Rb. Check also that you’ve installed the correct link options for the filter type. Next, connect one probe of your DMM to the 0V supply input, apply power and use the other probe to measure the supply voltages on the ICs. For a dual (±) or AC supply arrangement, check that there is +15V on pin 8 of ICs1-4. Similarly, there should be -15V on pin 4 of ICs1-3, while pin 4 of IC4 (if installed) should be at 0V. For the single supply arrangement, check for +15V on pin 8 of ICs1-3 and on pin 7 of IC4 (if installed). Note that the measured voltage will be lower if the supply voltage is less than 15V. Pin 6 of IC4 should be at half-supply SC (eg, 7.5V for a 15V supply). siliconchip.com.au STIC FANTAIDEA GIFT UDENTS FOR SFT ALL O S! AGE THEAMATEUR SCIENTIST An incredible CD with over 1000 classic projects from the pages of Scientific American, covering every field of science... NEW VERSION 4 – JUST RELEASED! GET THE LATEST VERSION NOW! Arguably THE most IMPORTANT collection of scientific projects ever put together! This is version 4, Super Science Fair Edition from the pages of Scientific American. As well as specific project material, the CDs contain hints and tips by experienced amateur scientists, details on building science apparatus, a large database of chemicals and so much more. ONLY 62 $ 00 PLUS $10 Pack and Post within Australia NZ P&P: $AU12.00, Elsewhere: $AU18.00 “A must for every science student, science teacher, science lab . . . or simply for those with an enquiring mind . . .” Just a tiny selection of the incredible range of projects: ! Build a seismograph to study earthquakes ! Make soap bubbles that last for months ! Monitor the health of local streams ! Preserve biological specimens ! Build a carbon dioxide laser ! Grow bacteria cultures safely at home ! Build a ripple tank to study wave phenomena ! Discover how plants grow in low gravity ! Do strange experiments with sound ! Use a hot wire to study the crystal structure of steel ! Extract and purify DNA in your kitchen !Create a laser hologram ! Study variable stars like a pro ! Investigate vortexes in water ! Cultivate slime moulds ! Study the flight efficiency of soaring birds ! How to make an Electret ! Construct fluid lenses ! Raise butterflies as experimental animals ! Study the physics of spinning tops ! Build an apparatus for studying chaotic systems ! Detect metals in air, liquids, or solids ! Photograph an ant's brain and nervous system ! Use magnets to make fluids into solids ! Measure the metabolism of an insect . . . ! and many, many more (a thousand more, in fact!) See the V2 review in SILICON CHIP, October 2004. . . or read on line at siliconchip.com.au This is the ALL-NEW Version 4 . . . it’s even BETTER! HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-5 Mon-Fri BY FAX:# <at> (02) 9939 2648 24 Hours 7 Days BY EMAIL:# silicon<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# BY PAYPAL:# PO Box 139, Collaroy NSW 2097 silicon<at>siliconchip.com.au 24 Hours 7 Days * Please have your credit card handy! # Don’t forget to include your name, address, phone no and credit card details. BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information There’s also a handy order form inside this issue. Exclusive in SILICON Australia to: CHIP siliconchip.com.au siliconchip.com.au July 2009  69 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. SMALL TELESCOPIC ANTENNA 4.7k 4.7k G2 L1 TUNING VR1 VC2 5k VC1 LIN GAIN G1 Q1 B D 470 10nF 560 10nF OUTPUT TO SONY 7600G Q2 E S 10nF C 10k 100k B C 9V BATTERY E Q3 L1: 35T CLOSE WOUND ON 10mm DIAMETER FORMER VC1, VC2: BOTH SECTIONS OF A PLASTIC DIELECTRIC AM TUNING CAPACITOR 10nF Q1: 40673, 3N211, 3N212 ETC. RF preamplifier for world-band receivers Synthesised world-band receivers are very popular but they do suffer generally from poor reception with the standard telescopic aerial. The radios are very sensitive by themselves but the aerial is far too short on the lower shortwave bands to supply any reasonable signal for good reception, the result being hiss and noise. Wideband RF stages do not lend themselves to being connected to large antennas and usually suffer from overloading and cross modulation problems. The circuit described here combines modest gain with a tuned RF stage to help reduce outof-band signals. Inductor L1 and plastic dielectric variable capacitor VC1 comprise a tuned circuit, resonant to the band of interest. Dual-gate MOSFET Q1 then buffers the high impedance of the tuned circuit and also provides some gain which is limited by its unbypassed 470Ω source resistor. Transistor Q2 functions as an emitter follower to buffer the drain output of the MOSFET before it is fed into the antenna input of the radio. Q3 functions as a switch, automatically turning the preamplifier on when the radio is activated. The Sony ICF7600GR, the radio for which this circuit was developed, has approximately 3.5V present at the external antenna input when switched on. This voltage will turn Q3 fully on via its 10kΩ bias resistor, thereby connecting the 9V internal supply of the preamp. The overall gain is adjusted by VR1, allowing approximately +6dB gain when wound fully clockwise. When rotated fully anticlockwise, Q2,Q3: BC547 Q1: 3N211/212 B E G1 C G2 S D VR1 will attenuate the signal by around the same amount, which is very useful with strong signals. Other world-band radios may not have this external antenna voltage present, in which case Q3 can be omitted and a normal switch used instead. The current drain is around 10mA and a small 9V battery will provide many hours of operation. Inductor L1 is wound using 35 turns of enamelled wire (scrounged from a small transformer) on part of a ballpoint pen case. The tuning capacitor can be recycled from a defunct transistor radio, as can the gain control pot and telescopic aerial. The circuit can be constructed on a scrap of copper circuit board and housed in a small zippy box. A short cable is made to connect to the radio’s external antenna input. Dayle Edwards, Westland, New Zealand. ($45) C h o o s e Yo u r P r i z e There are now five great reasons to send in your circuit idea for publication in SILICON CHIP. We pay for each item published or better still, the best item in “Circuit Notebook” each month will entitle the author to choose one of four prizes: (1) an LCR40 LCR meter, (2) a DCA55 Semiconductor Component Analyser, (3) an ESR60 Equivalent Series Resistance Analyser or (4) an SCR100 Thyristor & Triac Analyser, with the compliments of 70  Silicon Chip Peak Electronic Design Ltd. See their website at www.peakelec.co.uk So now you have even more reasons to send that brilliant circuit in. Send it to SILICON CHIP and you could be a winner. You can either email your idea to silchip<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. siliconchip.com.au +5V Signal inverter runs from a 5V rail This circuit is designed to be a basic signal inverter. It takes a negative or positive-going voltage signal and inverts it. The circuit consists of a 741 op amp (IC1) and a 555 timer (IC2). IC2 runs as an astable multivibrator which drives a diode pump circuit consisting of diodes D1 & D2 and the 1µF & 22µF capacitors. This generates the negative supply rail for the 741 op amp which otherwise could not deliver a negative polarity signal. Hence IC1 has positive and negative supply rails, as needed for normal operation. It is connected as an inverting amplifier stage with unity gain, as determined by the 10kΩ input and feedback resistors. Note that there are no signal coupling capacitors in the circuit, necessary to ensure that the op amp can deliver DC output signals. With no input signal applied, there will be NEGATIVE VOLTAGE INPUT (TO BE INVERTED) 10k 7 2 3 IC1 741 6 4 1k 7 6 1k 8 4 3 IC2 555 2 100nF 5 D2 1 F K A – D1 1 10nF 100 F A + K 22 F 0V D1,D2: 1N4004 A a slight DC offset error at the output of the op amp. The original use for this circuit was to invert the signal from an AD­ 595 thermocouple decoder, which Twin-tub washing machines are economical in water usage but do have drawbacks. Having to manually fill the spin side with water for final rinse requires continual monitoring otherwise there is the risk of water overflowing onto the floor. The resultant slippery floor can be a hazard unless it is mopped up immediately. This circuit was designed to detect moisture on the laundry floor, with the sensor placed directly under the washing machine. In essence, the circuit uses two NPN transistors in a Darlington configuration. The base of the first transistor, Q1, is fed via the moisture sensor and a 10kΩ resistor. If there is no moisture present, the transistor is held off by the 1MΩ resistor connected from the base to the 0V line. Once the resistance of the moisture sensor falls below about 4MΩ, Q1 will turn on as will Q2 and this powers the piezo alarm. It will continue to beep for about 15 seconds until the 2200µF supply capacitor is discharged. The 2200µF capacitor is charged by the 56kΩ resistor from the 9V battery supply. When the sensor has been dried out completely, the circuit can be used again and recharging of the 2200µF capacitor will take about five minutes. When the moisture sensor is open-circuit (ie, no moisture is present), the standby current is almost solely dependent on the leakage of the electrolytic capacitor. For a good capacitor, this should only be K delivers negative voltages for negative temperatures but there are many other applications. Reuben Posthuma, Christchurch, New Zealand. ($35) Simple water spillage alarm siliconchip.com.au POSITIVE VOLTAGE OUTPUT (TO ADC OR SIMILAR) 10k 56k 2200 F 16V 10k 10k SENSOR B C E 1M + PIEZO SOUNDER – Q1 BC548 B 1M C E 9V BATTERY Q2 BC548 BC548 B E C a few microamps so battery life should be very long. Any general-purpose small-signal silicon NPN transistors can be used. The alarm sounder is a Jaycar AB-3456 with the yellow and black leads connected for pulse (beep) operation. The red lead is not connected. The sensor is made up from a strip of Veroboard, with alternate tracks bridged together and 1mm copper wire strips soldered along the tracks to keep the board slightly raised off the floor. The sensor is then lacquered and the wire strips slightly sanded for exposure to floor contact. The circuit, 9V battery and sounder were fitted into a small plastic utility box (UB5) with a circular cut-out for the alarm. Warwick Talbot, Toowoomba, Qld. ($40) July 2009  71 Circuit Notebook – Continued +12V 100nF 16 Vdd 100nF O0 O3 O4 10 K ZD1 12V CP O5 22k O6 4.7nF O9 O10 10k 11 O11 MR O12 O13 Vss 15 7 1 5 2 4 8 14 6 13 14 O6 3 4 2 4 7 O3 14 6 IC3b CP0 O2 O1 5 13 IC2: 4023B IC3: 4025B 3 CP1 Vss 8 D3 D1 K 11 9 9 8 6 7 5 6 1 5 IC4 4017B O4 10 9 IC3a 8 3 O5 14 1 2 6 IC2b 5 15 1 O9 O7 A O0 4 7 3 4 2 2 1 3 0 A 16 A 9V K A K +12V 1000 F A O5 RESET 100nF (MOM) O3 – A LED2 START A 13 D1-D3: 1N4148 K This timer is very accurate, has long-term stability and requires no calibration. It does not use a crystalcontrolled oscillator or a PIC with an internal resonator. Instead, it uses the 50Hz mains to derive its clock pulses. In the form presented here it is a kitchen minute timer but the design can be extended to include seconds or hours as required. Power is provided by a 9V AC plugpack which is rectified to supply a DC voltage of between 12V & 13V. When power is first applied, A PIEZO BUZZER O2 B 10k K CP1 Vss 8 10 11 IC3c 9 8 6 7 5 6 1 5 O0 4 7 3 4 2 2 1 3 0 1N4004 A all counters are automatically reset. Switch S1 is a DPDT (double-pole, double-throw) type with a centre-off position. One side is a momentary contact which is used to reset the timer. The other side of S1 provides power to the alarm which will sound at the end of the timing period. It also provides half-wave rectified 50Hz pulses via diode D1 to IC1, a 4020 14-bit binary counter. The centreoff position will turn off the alarm which will sound continuously until attended to. The 50Hz pulses are fed to the clock input (pin 10) of IC1 after signal conditioning by an RC filter K S2 MINUTES x10 O5-9 12 10 12 11 IC2c 12 7 13 13 E K Accurate timer locked to 50Hz mains supply 72  Silicon Chip C Q1  K ZD1 CP0 O1 A 9 11 IC5 4017B O4 10 560  O9 O6 START S3b + LED1 POWER 100nF O7 100nF 560 MR 1M 14 9V AC PLUGPACK Vdd O8 A A K 15 S3a D4-D7: 1N4004 K +12V D2 START S1 MINUTES x1 O5-9 12 K 1M 230V MR O8 8 K Vdd 9 IC2a 100nF 16 9 O7 IC1 4020B O8 12 A 100nF Q1: BC548 B E LEDS C K A (22kΩ & 4.7nF) and clipping by zener diode ZD1. Since we are interested in obtaining a 1-minute interval, IC1 is used to count 3000 of the 20ms pulses from D1. A count of 3000 in binary is 101110111000 so we need to detect when outputs Q4, Q5, Q6, Q8, Q9, Q10 & Q12 are simultaneously high. This is achieved using NAND gates IC2a & IC2b and NOR gates IC3b & IC3a. The output of IC3a supplies a reset pulse to IC1 and clocks decade counter IC4, a 4017. IC4 counts single minutes and on reaching a count of 10, resets itself and advances the count on IC5 which counts 10s of minutes. siliconchip.com.au m y Graha Geoffre onth’s is this m of a winner Test las Peak At ent u r t Ins m The enhanced software for the Appliance Energy Meter provides a much wider range of information, including predicted energy usage, predicted cost and CO2 emissions. Enhanced software for the Appliance Energy Meter The Appliance Energy Meter described in the July & August 2004 issues has been popular and is still available in kit form from Altronics (Cat. K4600). The original firmware was written in assembler and could only display a limited number of measurements (watts, accumulated kWh and cost). This replacement firmware is written in the C language and uses 32-bit floating point routines to provide a much wider range of information, including predictions of the energy cost over time and CO2 emissions. The above diagram shows all the readings that you can call up. To install the new firmware you need to replace the original PIC16F628 microcontroller with a PIC16F88-I/P. The 16F88 is pin-forpin compatible with the original microcontroller but has double the program memory and this is used to implement the new functions. The only function of the original design that the new firmware does not cater for is brownout detection. As compensation, you get a much faster update rate (every second) compared to the original design (every 11 seconds). To install the new firmware, sim- ply download the HEX file from the SILICON CHIP website, program it into a PIC16F88-I/P microcontroller and install it in the Appliance Energy Meter. No other modifications are required. To reset the meter and start accumulating a new set of readings you press the CLEAR button. The FUNCTION button will step you down through the five “layers” of readings as shown in the diagram. The UP and DOWN buttons will step you right or left on a horizontal line. To set up the meter you hold down the CLEAR button for five or more seconds and the display will change to the calibration settings. To adjust a setting, use the UP and DOWN buttons as required. To step to the next setting, press the FUNCTION button. When you have run through all the calibration settings the display will revert to normal measurement. In total, there are five calibration settings: cost of electricity, number of days between electricity bills, the rate of CO2 emissions per kWH (your electricity supplier can tell you this – check their website), zero setting and calibration factor. If you wrote down the settings for the last two in the original firmware, you can re-enter the numbers here. Alternatively, refer to the original article for details on setting them. The firmware predicts energy usage by averaging the readings over time. For something that draws constant power, the prediction is accurate after a few seconds but for an appliance that varies its power (like a fridge) you will need to leave it connected for a few days until the predictions settle to a constant value. You can use this technique to measure the real cost of running many appliances, including your computer, water pump and even your electric kettle. For example, you can connect this to your “power hungry” plasma TV and after a while it will have averaged the on/off times dictated by your viewing habits. You can then display how much it will cost you per bill, per year and even how much it will contribute to global warming. Geoffrey Graham, Perth, W.A. Note: all parts in the Appliance Energy Meter (including the display) operate at 230VAC. Be sure to disconnect it from the mains before opening the lid. The timer is consequently capable of timing intervals up to 99 minutes. The time interval is set by switches S2 & S3 which select the appropriate outputs of IC4 and IC5. When the selected outputs are both high, this condition is detected by NAND gate IC2c and inverted by IC3c. The resulting high input is applied to pin 13 of IC4, inhibiting further counting. The high also turns on BC548 transistor Q1 which sounds the buzzer. The buzzer continues to sound until power is removed from the buzzer circuit by returning switch S1 to its centre-OFF position. As output 10 of IC2c is high throughout the timing period, it could be used to control a relay which would switch a device on for the timing period. Jack Holliday, Nathan, Qld. ($55) siliconchip.com.au July 2009  73 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ A quick look at Australia’s largest IT show . . . CeBIT 2009 by Ross Tester T o stand out from the crowd (and believe me, it can be very crowded at CeBIT) you need something different. Whether that is a “wow!” stand (and there were a few of those) or a “gee whiz!” product, you needed something to stop the passersby passing by . . . At the very least you need something to make visitors remember you, your stand, your products or at least your name. Bags displaying a name or logo (or both) are very popular, if only to carry home all the brochures before they’re put in the recycling bin. Last year, I recall one of the stands handing out monster-sized yellow bags. Everywhere you looked, you saw those bags. The smaller bags that everyone else handed out were stuffed inside the big bags! I also recall talking to the stand staff and their philosophy was simple: the guys with the biggest bags win. Yep, they won at least as far as exposure was concerned. While there was none of that this year (an edict from the organisers, maybe?), the NSW Government stand certainly took the prize for the bestbag-at-show. None of your Woolies and Coles bio-degradable politically correct bags here: your taxes went into a you-beaut, zippered (waterproof?) bag complete with compartments for your mobile phone and business cards. (And there were a lot of those bags with similar-sized bags crammed into them so I guess they won this year!). But of course, CeBIT is much more than bags. It’s about getting your message out to those who are interested (or might become interested if you’re a good talker) into buying your product or service. To be frank, I find it hard to comprehend the number of stands at shows like CeBIT all trying to flog the same type of products. There were countless 78  Silicon Chip companies selling countless software applications – it would appear that anything that started with an “e” was available: emarketing, ecommerce, elearning, etracking, epayments, ehr (how you can have e human resources is a bit beyond me) and so much more – even egovernment, courtesy of Kevin’s sales team. I noticed a lot more companies specialising in wireless – long range wifi figured prominently once again, as did several companies specialising in the “nuts and bolts” of wireless LANs and WANs, everything from the electronics right down to the connectors. And there were the ubiquitous “sign up now special CeBIT deals” for all manner of goods and services. Not the least was “only while show lasts” broadband special offers. I’m not convinced those people going to CeBIT would fit the demographic of wanting to switch ISPs etc but given If you look closely, you might notice the new “Shuttle X50” all-in-one PC... it’s due to go on sale at the same time as this issue of SILICON CHIP. the number of them and the fact that they come back year after year, they must figure it’s worth it. One such company I spoke to (who must, of course, remain nameless) said that they were definitely questioning their CeBIT attendance next year. They had already reduced the size of their stand to a quarter what it used to be, mainly because the number of leads had been steadily decreasing over the past three years. They had over 500 the first year and were even happy with the 350 the following year. Last year it was down to 250 and when I talked to them late on the second day, their follow-up book had just over a hundred entries in it. That’s a pretty expensive form of advertising, even if – and it’s a big if – those hundred are quality leads. It’s not just the floor space (expensive!) but building and fitting out the stand (expensive!) staffing it for the four days (expensive!) . . . you get the picture. CeBIT, held from May 10-12, occupied three halls at Sydney Convention and Exhibition Centre so it’s no small show! It’s broken down into quite a number of areas which specialise in certain fields – for example, VOIP, networking, wireless, telecoms, smart cards, RFID, POS, navigation, IT security, business software (almost a whole hall), data centres, IT hardware, financial services and so on. Then there were the various Government stalls (Australian, state and overseas) which, given their large budgets, mostly had the largest areas. Many of the big players in the IT game were present but many were conspicuous by their absence. One of the big boys that was there, raising my eyebrows at least, was Google. When a company name has entered the lexicon as a noun and verb in its own right (you don’t search on line any more, you Google!), one wonders which market siliconchip.com.au they were addressing at CeBIT! Newsprout, an ISP based on the north coast of NSW, had an interesting gimmick: handing out tiny plants (Vibirnum, a very hardy, easily grown shrub in any sunny or partly shaded position with moist well-drained soil, if you were wondering!) – in keeping with their name. A lot of their push was “green” but they also claimed to be able to keep up with the big boys when it came to service and speed. (www.newsprout.com.au). One of the most popular stands, at least at the time I was there, was Altech Computers. They had quite a variety of “new and unusual” products but the one that took my eye was the very new “Shuttle” X50 all-in-one PC. It’s a 15.6-inch LCD touchscreen with the PC built in. No keyboard, no mouse. It suits a wide range of applications including digital signage, kiosks, etc. It was so new at the time they only had one in the country – the one on display – but they expected stock to arrive around now (www.altech.com.au) The CSIRO had a rather interesting stand, not only because of the variety of applications displayed but also because of the experts they had on the stand to explain the applications and what the CSIRO is doing. Of particular interest was one of the Government’s big “pushes” at the moment, broadband to the bush: the CSIRO has developed a wireless system which uses existing infrastructure to deliver 12 megabit/s internet access up to 100km from the antenna. An upgraded system will deliver over 50 megabits/s. (www. csiro.au). One tiny stand (the smallest available!) had a real show-stopper, at least if the show crowds stopping were They reckoned this notebook case was rugged enough to go onto building sites and be walked on, even driven over! siliconchip.com.au any guide. Scinet are the Australian distributors for Dino-Lite handheld microscopes, which plug into a USB port. I was impressed with the veryclose-up display of PC board soldering. They had two models on display, both priced under $500 and they seemed to give a very good account of themselves. (www.scinet.com.au) IT security, both data and hardware, was featured heavily. With laptop/ notebook sales now far exceeding desktop machines, Trace Technologies were proudly showing off their “Laptop Cop” system which not only lets you find out where your stolen laptop is (they claim to within 15m via cell triangulation!) but lets you control it when the crook uses it on the ‘net for the first time – without the thief’s knowledge. So you can remotely delete or retrieve important or sensitive files, then get it back (and hopefully apprehend the thief). (www. tracetechnologies.com.au) Another “felon”-related application was the Federal Government’s “CrimTrac” system – the awardwinning crime-fighting tool. CrimTrac was established to allow police forces across Australia to share information, to solve crimes and catch criminals. It’s now evolved into a national automated fingerprint ID system, a national criminal investigation DNA database, a national Child Sex Offender register and a national Police Reference System providing rapid access to operational policing data. CrimTrac’s record is already very impressive and we hope to provide more insight into this system in the future. (www.crimtrac.gov.au) Data recovery was also a feature – and we plan to look at this area in significantly more detail in the future. One company was demonstrating its approach to the subject with a number of open, spinning hard drives. I don’t think Xyber Data Recovery expects them to ever work again but they looked impressive. As well as hard disks, they also extract data from bent flash, tape, RAID and so on. (www. xyber.com.au) Away from the halls was another part of CeBIT, the virtually continuous seminars and presentations by and for industry luminaries. We didn’t have the time to attend any of these but if the number of press releases they generated is any guide, they were well received. There were also numerous Scinet’s Dino-lite handheld (or in this case stand-held) USB microscopes. anyone-can-attend seminars held inside the CeBIT display halls, of particular note those of telecoms guru Paul Budde. We did manage to poke our head into one of these, if only for a few minutes. When deadlines loom, seminars are an unaffordable luxury. Overall? One of the main reasons we look at shows like CeBIT (and let’s face it, CeBIT is the largest such show in Australia) is to see where the IT industry is up to and to keep abreast of the latest and greatest products. From that point of view, CeBIT was, with some exceptions, disappointing this year. Sure, there was lots of razamatazz but there wasn’t all that much in the way of innovation. But as we said earlier, we go to keep abreast of the “IT” times and from that point of view, quite worthwhile. SC We spotted these earphones (?) on the Korean Business stand. They don’t go in the ear but on the ear, allowing you to still hear ambient sound (eg, sirens). They sounded good, too! July 2009  79 Calibrating, Setting the Battery Capacit Last month we presented the full description, operation and construction details of our new Battery Capacity Meter. This month we guide you through the once-only setup and calibration. We also explain in detail how to use it! Part 2 – by Mauro Grassi A SSUMING YOU have completed the Battery Capacity Meter and installed it in its case, now it’s time to calibrate it and set it up, ready for use. We’ve also shown the various LCD readouts and what they mean – sorry the type is so tiny but we had to get a lot of information in! After use, most of these screen messages and sub-menus will become very much self-explanatory and common sense. And you can always refer back to this article if you need to! One Time Calibration To calibrate the meter, you will need to follow these steps: (1) Measure the voltage between pin 2 (GND) and pin 1 (+5V Rail) of CON4 using a DMM. Note this voltage and enter it in the CALIBRATION>Set +5V Rail SubMenu; (2) Measure the voltage between pin 2 (GND) and pin 5 (Low Battery Voltage) of CON4 using a DMM. Note this voltage and enter it in the CALIBRATION>Calibrate Lo. Divider SubMenu; (3) Measure the voltage between pin 2 (GND) and pin 6 (High Battery Voltage) of CON4 using a DMM. Note this voltage and enter it in the CALIBRATION>Calibrate Hi. Divider SubMenu; (4) Enter the value of your shunt resistance (in mΩ) in the 80  Silicon Chip STANDBY Mode: This flashes periodically when the meter is in standby mode. It goes into Standby mode when the load & charge currents are below the set threshold. USB must be disconnected for this to occur. In Standby mode, the meter consumes minimal power, turning the LCD backlight off. Use S1to bring the meter out of standby. SHUTDOWN Mode: This message appears briefly before the meter shuts down due to the battery voltage being lower than the shutdown voltage. This is a fail-safe way of protecting the battery. For example, a 12V SLA battery, should not be discharged below 11V. TURN METER OFF SubMenu Message: This message appears briefly if you've requested to turn off the meter manually by going to the 'Turn Meter Off' submenu and confirmed the action but the USB is connected. Since power is delivered through the USB, the meter cannot perform the requested action. This shows the typical view of a menu. A Submenu is enclosed in '<' and '>' brackets. Here the top two entries of the Main Menu are shown. You can press 'A' and 'B' to go up and down the menu and the corresponding number to enter the SubMenu. For example, pressing 1 here takes you to the Battery SubMenu. The strings scroll from right to left to show the entire name of the SubMenu. The typical view of a SubMenu as a sequence of snapshots from top to bottom. A submenu item that has no other SubMenus is enclosed in '[' and ']' brackets. Top two entries of the System SubMenu are shown. Press 'A' and 'B' to go up and down the SubMenu and the corresponding number to enter the SubMenu – eg, pressing 1 takes you to the Beeper Status SubMenu to enable or disable the beep. The strings scroll from right to left to show the entire name of the SubMenu, as well as any values of the relevant settings. This sequence shows how the SubMenu items scroll from right to left and how the value of the setting is shown in the scrolling string. The top line contains the string 'Beeper Status: On' indicating that the beeper system is enabled. You can change it by pressing 1. The bottom line contains the string 'Average Samples: 30.0' indicating that presently, 30 readings are averaged at a time. You can change the number of readings that are averaged by pressing 2. If you changed the number of average samples to 120, then on returning to this SubMenu, the bottom string would read 'Average Samples: 120.0' instead. For numerical settings, enter the new value by using the number keys, the key '*' is for a decimal point & the key 'D' is used as backspace if you make a mistake in typing ('D' is for Delete). When you are satisfied with the entered value, press the '#' key to enter the value. If no input is entered but you then press the '#' key to exit, the current value of the setting is retained. For values which are not numerical, you use the 'A' and 'B' keys to vary the value up and down, respectively, and use the '#' key to exit the SubMenu. Most settings are numerical, where the range is also shown and you must enter a number in the valid range for the new value to be accepted. Here are the various system messages and their meanings. Also shown is a sequence of screens depicting how the SubMenus appear on the LCD readout. siliconchip.com.au Up & Using ty Meter PERCENT CHARGE PRESS '1' BATTERY CAPACITY AMP HOURS PRESS '2' BATTERY VOLTAGE VOLTS PRESS '3' LOAD CURRENT AMPS PRESS '4' CHARGE CURRENT AMPS PRESS '5' NET CURRENT AMPS PRESS '6' TIME REMAINING IF DISCHARGING PRESS '7' TIME CHARGING IF CHARGING PERCENT CHARGE PRESS '8' BATTERY VOLTAGE CIRCUIT CURRENT MILLIAMPS PRESS '9' RELAY CURRENT MILLIAMPS (5) (6) (7) (8) (9) CALIBRATION>Shunt Resistance SubMenu; Enter the CALIBRATION> Calibrate Current SubMenu. Apply a small load of say a few amps to the LOAD terminal through a DMM. Note the current registered on the DMM and enter it; Enter the value of the gain of the load amplifier (usually 60.0 for the MAX4080SASA) in the CALIBRATION>Load Amp. Gain SubMenu; Enter the value of the gain of the charge amplifier (usually 60.0 for the MAX4080SASA) in the CALIBRATION>Charge Amp. Gain SubMenu; Enter the value of your sense resistance (usually 10Ω) in the CALIBRATION>Sense Resistance SubMenu; Enter the CALIBRATION>Detect Sense Resistance SubMenu. Connect the DMM in series between the GND terminal of the meter and the negative battery terminal. Note the instantaneous circuit siliconchip.com.au current and enter it (in mA). That completes the calibration. One-time user setup After the calibration is performed, you should run through the following checklist to set up your preferences: (1) Go to the BATTERY SubMenu; (2) Enter the full capacity of your battery in the Battery Capacity SubMenu; (3) Enter Peukert’s constant in the Peukert’s Constant SubMenu if you are using a Lead Acid battery; (4) Enter the cell chemistry in the Cell Chemistry SubMenu; (5) Enter the charging efficiency in the Charging Efficiency SubMenu; (6) Enter the cycle threshold in the Cycle Threshold SubMenu; (7) Exit the BATTERY SubMenu; (8) Go to the DISPLAY SubMenu and set up the display backlight preferences like brightness and time out period; CHARGE CURRENT AMPS PRESS 'A' LOAD CURRENT AMPS PERCENT CHARGE PRESS 'B' CHARGE/DISCHARGE CYCLES BATTERY VOLTAGE VOLTS PRESS 'C' BATTERY CURRENT AMPS BATTERY CAPACITY AMP-HOURS PRESS 'D' LOAD CURRENT AMPS BATTERY CAPACITY WATT-HOURS PRESS '*' LOAD POWER WATTS PRESS '0' TO SEE ALL READINGS, IN SCROLLING MODE. PRESS '#' TO ENTER THE MENU SYSTEM AND CHANGE SETTINGS. This shows all the available readings. Each is chosen by a single digit press on the alphanumeric keypad. For example, if you wish to display the battery voltage, type ‘3’. Or if you wish to see the battery capacity in Watt Hours and the load in Watts, press ‘*’. Notice that from here, you may press ‘#’ to enter the extensive menu system. The remaining panels illustrate in detail the various submenus. July 2009  81 (9) Go to the DETECTION SubMenu; (10) Enter the voltage below which to shut down in the ShutDown Voltage SubMenu; (11) Enter the low capacity alarm threshold in the Capacity Alarm SubMenu; (12) Enter the standby current threshold in the Standby Threshold SubMenu; (13) Enter the trickle current threshold in the Trickle Current SubMenu; (14) Enter the minimum voltage of your battery in the Min. Voltage SubMenu; (15)   Enter the maximum voltage of your battery in the Max. Voltage SubMenu; (16) Enter the Detection Period and number of detection points in the Detection Period and Detection Points SubMenus; (17) Exit the Detection SubMenu; (18) Enter the SYSTEM SubMenu; (19) Choose whether to enable or disable the audible alarm in the Beeper Status SubMenu; (20)   Choose the number of samples to average in the Average Samples SubMenu; (21)   Exit the SYSTEM SubMenu; (22) Enter the RELAY SubMenu; (23)   Choose whether you will use an external relay in the Relay System SubMenu; (24) If you are not using a relay, go to step 29; otherwise continue. (25)   Enter the relay coil resistance in the Relay Coil Resistance SubMenu; (26)   Enter the overload current and its duration in the Max. Load Current and Max. Current Duration SubMenus; (27)   Enter the relay off voltage in the Relay Off Voltage SubMenu; (28)   Enter the relay hysteresis value in the Relay Hysteresis SubMenu; (29)   Exit the RELAY SubMenu; (30)   If required, set up the logging options in the LOGGING SubMenu. Full Speed (12Mbps) USB 2.0 The firmware implements a USB 2.0 full speed bulk Fig.8: this Window appears when the meter is connected to a PC for the first time, using the USB interface. 82  Silicon Chip transfer bidirectional endpoint (EP1) with packet size set to 112 Bytes. This is used to communicate with the host program on the PC (battcap.exe) through the custom Microchip driver (MCHPUSB). We explain how to install the driver on Windows OSs below. Endpoint 0 is implemented as well, as that is mandatory for any USB device. A transaction between the host program on the PC and the battery meter consists in sending a 112-Byte packet to the meter. The firmware will decode the packet, according to the sent command, and update itself accordingly. The meter can also send logging data to the PC. Remember that the USB driver must be installed correctly for this to work. Instructions are given below. Software setup and driver installation for Windows The meter’s USB device interface uses the generic Microchip driver for Windows. Before communicating with the display using the PC host program, you will need to install this driver. This section explains how to install the driver in Windows XP, although other versions of Windows will be similar. You should have first downloaded the Microchip installer (MCHPFSUSB_Setup_v1.3.exe) from the SILICON CHIP website and ran it. Note that you must use version 1.3. Older or Newer Versions may not be compatible. This will (normally) install the driver in the C:\MCHPFUSB\ Pc\MCHPUSB Driver\Release directory. When you first connect the meter to your computer using a USB cable, Windows will recognize the device as a “Meter” and a “Microchip Custom USB device”. The ‘Found New Hardware’ Window appears as shown in Fig.8 and you should select the “No, not this time” option and click “Next”. You will be presented with the next screen as shown in Fig.9. Select “Install from a list or specific location” and click “Next” again. The final screen is as shown in Fig.10. Select “Search for the best driver in these locations” and enable the “Include this location in the search” box as shown. Now click the Fig.9: use the “install from a list or specific location” option to select the correct driver to install. siliconchip.com.au “Browse” button. In the “Locate File” window that appears, navigate to where the MCHPUSB files were installed. Normally it will be C:\MCHPFUSB\Pc\MCHPUSB Driver\ Release. Choose the file “mchpusb.inf”. Select that file, and then click “Next”. Windows should install the driver. If the driver is installed correctly you should be able to see the meter in device manager (under Control Panel>System (Hardware Tab)), as shown in Fig.11. Using the PC host software To install the PC host program, first download the compressed file battcap.zip from the SILICON CHIP website www.siliconchip.com.au (go to the downloads section under July 2009). Extract the files in the zipped file to a directory on your hard drive. There should be these files: (1) battcap.exe: this is the executable command line program. (2) battcap.map: this is an internal file, needed for the host program to work properly. As long as it is copied to the same directory as battcap.exe the program will recognise it. This file is produced by the C compiler of the firmware. It contains memory mapping information for the firmware produced by the linker. When and if the firmware is updated, the map file will change. Using the software Battcap.exe is a command line program () with three options. The -i option is used to get system settings (‘i’ stands for information). A screen grab is shown in Fig.12. So you would type at the command prompt: battcap -i. The -x option is used to get the current readings which will update continuously every second or so (a screen grab is shown in Fig.13). Finally, the -l option is used for data logging. You will be asked to confirm whether you wish to transfer the data to your PC (as this will empty the local buffer). If you choose ‘Yes’, you will be prompted for a file name (it should have a .csv extension). The default file name will contain the local time and date. The data dumped to that file will be in Comma Separated Fig.10: selecting the path to the driver previously downloaded from the SILICON CHIP website. siliconchip.com.au Fig.11: a view of Device Manager when the driver has been correctly installed and the meter is connected via the USB. Values format and can be imported into a spreadsheet. Once the data is in your spreadsheet you can use its graphing functions to produce a graph, as shown in Fig.14. Changing the hardware to suit your application (advanced) There are several hardware values which can modified to suit your application. The sense resistor can be changed from the default of 10Ω (you should enter the correct value for your application in the CALIBRATION>Sense Resistance SubMenu). You can choose to use a different version of the MAX4080 chip for the load or charge sensing if your charging currents are always much smaller than your load currents (to increase the resolution). You can then change the value of the gain in the corresponding submenu (hint: they are in the CALIBRATION SubMenu). Moreover, you can choose different resistors for the two voltage dividers as long as you then calibrate them by going to the CALIBRATION SubMenu. You can change the current shunt to get a different maximum current range. In this case, you should both enter the new value of the shunt resistance in the CALIBRATION>Shunt Resistance SubMenu and then go to the CALIBRATION>Calibrate Current SubMenu and follow the prompts. To turn power on, press S1. To see a particular reading, press the corresponding key on the keypad, according to the readings panel shown on p81. For example, to see the July 2009  83 CALIBRATION SUBMENUS BATTERY SUBMENUS DECLARE FULL NOW SubMenu: Use this menu to declare that the battery is now full. Press '*' to confirm the action and '#' to cancel it. BATTERY CAPACITY SubMenu: enter the capacity of the battery in AmpHours from 0 to 999999 AH. CALIBRATE LO DIVIDER SubMenu: calibrates the low voltage divider. Enter the voltage at the Low Battery terminal, pin 5 of the calibration connector. PEUKERT'S CONSTANT SubMenu: enter the value of Peukert's constant for your battery. Allowed input is from 1.0 to 2.0. Typically 1.1. This only applies to Lead-Acid batteries. CALIBRATE HI DIVIDER SubMenu: calibrates the high voltage divider. Enter the voltage at the High Battery terminal, pin 6 of the calibration connector. CHEMISTRY SubMenu: sets the Chemistry. Use 'A' and 'B' to change the value and '#' to finish. Allowed values are Nickel or Lead-Acid. Note that Nickel includes both NiMH and NiCad. SHUNT RESISTANCE SubMenu: sets the value of the shunt resistance in milliohms. This value can be further automatically calibrated by using the CALIBRATE CURRENT SubMenu below. EFFICIENCY SubMenu: sets the charging efficiency of your charger/battery combination. It is a percentage between 0.1 and 100. Typically 80%. CALIBRATE CURRENT SubMenu: calibrate the value of the shunt resistance automatically. This is calculated from the entered instantanenous value of the load current. CYCLE THRESHOLD SubMenu: sets the cycle detection threshold. It is a percentage between 10 and 40. Typically 25%. This also clears the cycle count. LOAD AMP GAIN SubMenu: sets the value of the load amplifier gain. Typically, this is 60 for the MAX4080SASA. For the MAX4080TASA it is 20. CHARGE AMP GAIN SubMenu: sets the value of the charge amplifier gain. Typically this is 60 for the MAX4080SASA. It is independent of the load amplifier. DISPLAY SUBMENUS BRIGHTNESS SubMenu: sets the brightness of the LCD Backlight. Use the 'A' and 'B' buttons to change and '#' to set. The value is a percentage of full brightness. TIMEOUT SubMenu: sets the backlight timeout period in seconds. Typically 15 seconds. battery voltage you press ‘3’. To enter the menu system, press ‘#’. Once in the menu system, use ‘A’ and ‘B’ to move up and down the menu and the number digits to enter a SubMenu. To enter numbers, you use the digits, the ‘*’ for the decimal point and the ‘D’ key as backspace. In all cases you use the ‘#’ to exit the SubMenu and go back to the previous menu. From the main menu, press ‘#’ to exit the menu system and restore the current reading. You should also refer to the panels which explain the menu system in more detail. Peukert’s Law and efficiency For lead-acid batteries, Peukert’s law states that the change in capacity is not a linear function of the current drain. Specifically, Peukert’s law states that: ∆C = Ik∆t where ∆C is the capacity, ∆t is the time, I is the instantaneous current drain and k is a constant higher than 1.0 and typically between 1.1 and 1.3. The meter will take into account Peukert’s law when computing the capacity of the battery. The value of the constant k will vary for different batteries and you must set this in the BATTERY>Peukert’s Constant SubMenu. There is no easy way to compute the correct “k” value for your system. It is there as a way of adjusting the meter 84  Silicon Chip SET 5V RAIL SubMenu: calibrates the ADC system by entering the voltage of the 5V rail. SENSE RESISTANCE SubMenu: sets the value of the sense resistor in Ohms. Typically this is 10. This can also be automatically set by using the DETECT SENSE RESISTANCE SubMenu below. DETECT SENSE RES. SubMenu: automatically calibrates the value of the sense resistor by entering the value of the instantaneous circuit current. if you have enough experience with the meter and wish to tune it. Cell chemistry and synchronisation By synchronisation, we mean that when certain conditions are met, the meter sets the capacity to either full or empty capacity automatically. You can see at any time when the last synchronisation occurred by going to the DETECTION>Last Sync. SubMenu. For example, when the meter detects the end of charge, it sets the capacity to full capacity. The synchronisation algorithms are different depending on the cell chemistry. For Nickel-based batteries, the full capacity synchronisation occurs if the meter detects a trickle charge and the battery voltage is above the maximum voltage for the duration of the detection period. When the battery voltage is detected to be dropping and is below the minimum voltage (for the duration of the detection period and is monotonically decreasing at each detection point) then the battery capacity is synchronised to zero. This is because a Nickel battery’s voltage will, once it has been discharged beyond a point, drop dramatically and quickly. For a lead-acid battery, the end of charge is detected if there is a trickle current and the battery voltage is above siliconchip.com.au DETECTION SUBMENUS SYSTEM SUBMENUS SHUTDOWN VOLTAGE SubMenu: sets the voltage below which the meter will shut down to protect the battery -- eg, 11V for a SLA Battery. BEEPER STATUS SubMenu: enables or disables the beeper function using the 'A' and 'B' buttons. Use the '#' button to exit. CAPACITY ALARM SubMenu: sets the capacity below which the meter will emit an audible alarm. Use the 'A' and 'B' buttons to change and '#' to set. Typically 0%. It ranges from -60% to 100%. AVERAGE SAMPLES SubMenu: sets the number of samples that will be averaged for all readings. Typically this is 30. STANDBY THRESHOLD SubMenu: sets the current threshold. When the load and charge currents are below this, the meter enters Standby mode. Typically 0.05A. FIRMWARE VERSION SubMenu: shows the firmware version. Useful for debugging or reporting bugs or errors. TRICKLE CURRENT SubMenu: sets the trickle current. When the charging current is below this the meter considers the battery to be trickle charging. Typically 1/100th of the AH capacity. MIN. VOLTAGE SubMenu: sets the minimum voltage of the battery - eg, for a SLA this may be typically 11.5V, whereas for a NiMH battery this could be typically 1.1V per cell. LAST SYNC. SubMenu: shows the time elapsed since the last time the battery capacity was synchronised. A value of N/A indicates the capacity has not been recently synchronised. MAX. VOLTAGE SubMenu: sets the maximum voltage of the battery - eg, for a SLA this may be typically 13.8V, whereas for a NiMH battery this could be typically 1.2V per cell. LAST LOG SAMPLE SubMenu: shows how much time has elapsed since the last log sample was captured. DETECTION PERIOD SubMenu: sets the detection period in seconds for synchronising the battery capacity. Typically 30 seconds. DETECTION POINTS SubMenu: sets the number of intervals in the detection period. Used only for Nickel batteries. Typically 4 points. LAST SYNC. SubMenu: shows the time elapsed since the last time the battery capacity was synchronised. A value of N/A indicates the capacity has not been recently synchronised. DETECTION SUBMENU the maximum voltage for the duration of the detection period. In this case, the battery capacity is again set to full capacity. Note that there is no empty capacity synchronisation for Lead Acid batteries. However, you should note that Lead Acid batteries should never be discharged beyond a certain point or they will be damaged. Set the detection period by going to the DETECTION >Detection Period SubMenu. A typical value here is 30 seconds. You should also set the number of detection points (only relevant for Nickel batteries). This is set at 4 by default. The trickle current threshold can be set by going to the DETECTION>Trickle Current SubMenu. This is typically C/100 or so of the full battery capacity. So for a 20Ah battery this would be close to 200mA. It really depends on your charger, however. Set the Standby current (the current below which the meter will go into standby), by going to the DETECTION>Standby Current SubMenu. A typical value will be 50mA. The meter considers any current higher than the standby current and lower than the trickle threshold to be a trickle current for the purpose of synchronisation. Low capacity alarm An alarm will be heard when the capacity of the mesiliconchip.com.au USB CONNECTED SubMenu: indicates whether the meter is connected to a PC via the USB. The number in brackets is the state of the USB enumeration - eg 0=DETACHED, 6=CONFIGURED. TOTAL LOG TIME SubMenu: shows how much time has been logged in total. It indicates that this period of time has been logged. RESTORE DEFAULTS SubMenu: restores default values for most settings. Note that hardware-dependent settings such as the sense resistance aren't changed. TURN METER OFF SubMenu: turns the meter off. Note that USB power must be absent for this. The meter will turn off if the choice is confirmed by pressing '*'. SYSTEM SUBMENU ter falls below the set level (as a percentage). Go to the DETECTION>Capacity Alarm SubMenu to set the minimum capacity. The minimum capacity ranges from –60% to 100%. The capacity of the battery will go negative if it is discharged beyond the zero point. If you wish, you can disable the audible beeping by going to the SYSTEM>Beeper Status SubMenu and setting it to OFF. Overload and under-voltage protection An optional external relay can be connected to switch the load on and off. The charger can be left connected at all times, however, as shown in Fig.4 last month. The relay energises to connect the load to the load terminal of the shunt, so the shunt terminal can connect to the relay common and the load can connect to the relay’s NO (normally open) terminal. Once the relay is installed, the microcontroller will control it. If you decide to use a relay, make sure it is able to switch the required current. For an 80A system we recommend a 150A relay (eg, Jaycar SY-4073). If you are using lower currents there are several 60A automotive relays available, eg, Jaycar SY-4074 or Altronics S-4339. July 2009  85 LOGGING SUBMENUS RELAY SUBMENUS LOGGING ERROR SubMenu: sets the relative percentage error for logging RLE compression. The lower the error, the more resolution the data will exhibit. Typically 20%. RELAY SYSTEM SubMenu: enables or disables the relay system using buttons 'A' and 'B'. Use '#' to exit. When the relay system is off, the relay remains off. Turn off if you are not using an external relay. MIN. ABSOLUTE ERROR SubMenu: sets the minimum absolute error for logging RLE compression. The lower the error the more resolution the data will exhibit. Typically 0.1. RELAY COIL RESISTANCE SubMenu: sets the resistance of the coil of the external relay (optional). If you are using a dropping resistor in series with the coil, enter the total (ie, sum) of the coil & resistor. If you are not using a relay, disable it in the RELAY SYSTEM SubMenu below. SAMPLE PERIOD SubMenu: sets the sampling period in seconds. Samples are taken at a frequency equal to the reciprocal of this period. The range is from 200ms-1day. RELAY OFF VOLTAGE SubMenu: sets the voltage below which the relay switches off. Typically this is slightly higher than the minimum battery voltage. Ch. 1 LOGS SubMenu: sets what reading channel 1 logs. Use the buttons 'A' or 'B' to change and '#' to set. Here channel 1 is disabled. RELAY HYSTERESIS SubMenu: sets the voltage hysteresis added to the cut-off voltage. The relay will switch back on when the voltage exceeds this sum. Ch. 2 LOGS SubMenu: sets what reading channel 2 logs. Use the buttons 'A' or 'B' to change and '#' to set. Here it is set to log the battery voltage. MAX. LOAD CURRENT SubMenu: sets the maximum load current for overload protection. If the load current exceeds this current for the duration set below, the relay switches off. A soft-fuse then trips. It is reset by pressing S1. Ch. 3 LOGS SubMenu: sets what reading channel 3 logs. Use the buttons 'A' or 'B' to change and '#' to set. Here it is set to log the capacity percentage of full charge. MAX. CURRENT DURATION SubMenu: sets the maximum load current duration in seconds. The relay will switch off if the load current exceeds the max load current setting above for this time. Ch. 4 LOGS SubMenu: sets what reading channel 4 logs. Use the buttons 'A' or 'B' to change and '#' to set. Here it is set to log the charging current. OVERLOAD FUSE STATUS SubMenu: shows the state of the overload fuse. The fuse trips if there is an overcurrent condition. The only way to reset the fuse is to press S1. 'Short' means that the fuse allows current, 'Open' that it has blown. LOG MODE SubMenu: sets either CAPTURE mode (Cpt.) or OVERWRITE mode (Ovr.) for the RLE Buffer. Use the buttons 'A' or 'B' to change and '#' to set. RLE BUFFER POSITION SubMenu: shows the state of the RLE Buffer. The brackets indicate the start and end of the buffer and its position. The number of bytes in the buffer is also shown. RELAY SUBMENU This panel and the ones on previous pages show the various SubMenus – Detection, System, Logging, Relay, Battery, Display, Calibration – in more detail and how to access their parameters. Each of the submenus has a number of options and these are displayed in the LCD readout as you step through. LOGGING SUBMENU Note that these relays run from 12V. If your battery system is higher than 12V, a dropping resistor (in series with the relay coil) will be needed. Its value is calculated using Ohm’s law, taking into account the coil resistance of the relay. For example, if your relay coil resistance is 180Ω and yours is a 24V system, a 180Ω 5W resistor would be used. Similarly, for a 48V system you would need a 560Ω 5W resistor (actually 540Ω but 560Ω is the closest standard value). A 1N4004 (or similar) diode must be connected across the relay coil to quench any back-EMF when the relay switches off. See Fig.4 from last month. Enter the value of the coil (or coil and series resistor) in the RELAY>Relay Where to get the parts . . . At least one supplier will be making a kit available for the Smart Battery Capacity Meter. It is possible there will be others but Altronics have indicated that their stores and mail/web order will have a kit soon (Cat K1700) for $175.00 – see www.altronics.com.au If you wish to put together your own kit, then most parts are commonly available and you should have no problem obtaining them. One exception is the PC board which (as with all SILICON CHIP boards) is available in from RCS Radio, 41 Arlewis St, Chester Hill NSW 2162. Phone (02) 9738 0330. The only other component you may have problems obtaining is the programmed PIC­18F2550-I/SP microcontroller. This is available direct from SILICON CHIP for $25.00 including P&P. 86  Silicon Chip Coil Resistance SubMenu, as well as enabling the Relay System by going to the RELAY>Relay System SubMenu. On an under-voltage condition the relay will turn off, switching off the load and thereby saving the battery from possible (and irreparable) damage. Note that the relay “off” voltage is usually slightly higher than the shut down voltage (the latter, typically, should not ever be reached and is only a fail-safe measure as detailed shortly). The relay will only turn back on when the battery voltage rises above the sum of the relay off voltage and the relay hysteresis (both measured in Volts). This adds a measure of hysteresis avoiding ‘hunting’. The trip point and hysteresis are set by going to the RELAY>Relay Off Voltage & RELAY>Relay Hysteresis SubMenus. For an over-current condition, you set the maximum current and its duration before the relay switches off and trips a software fuse. siliconchip.com.au Fig.14: this screen grab is from the Microsoft Excel spreadsheet program. We have imported the CSV file obtained by running the command “battcap.exe -l” and graphed the battery voltage as a function of time. The relay (and hence the load) will remain off indefinitely after the fuse trips. The only way to reset this software fuse is to press S1. The battery voltage should bounce back up once the load is disconnected. Note that the relay will only turn back on once the voltage is above the sum of the relay off voltage and the hysteresis voltage. The relay system should be switched off (RELAY>Relay System) if not used. Fail-safe shutdown When the voltage of the battery drops below the level set in the DETECTION>ShutDown Voltage SubMenu, the circuit (as well as the relay) will turn off. This is a fail-safe measure and in normal operation should never occur. It is there to protect the battery in the last resort. After power is lost, the meter is turned on again by pressing S1. If the voltage is still too low, the meter will again shut down but not before you have a chance to access the menu system by pressing ‘#’. This allows you to change any settings if needs be, before the meter shuts down (so you are never ‘locked out’ completely). into VIDEO/TV/RF? Television & Video Technology – by KF Ibrahim New edition has a full and compre-hensive guide to video and TV tech-nology including HDTV and DVD, $ 58 starting with fundamentals. $ 70 NEW LOW PRICE! DVD Players and Drives $ 95 NEW LOW PRICE! $ 85 – by KF Ibrahim DVD technology and applications - ideal for engineers, technicians, students, installation and sales staff. Practical Guide To Satellite TV – by Garry Cratt The book written by an Aussie for Aussie conditions. Everything you need to know – including what you cannot do! 7th ed. $ 49 Hands-On Zigbee – by Fred Eady $ 9650 NEW LOW PRICE! $ 75 An in-depth look at the clever little 2.4GHz wireless chip that’s starting to be found in a wide range of equipment from consumer to industrial. $ There’s something to suit every RF fan in the SILICON CHIP reference bookshop: see the bookshop pages in this issue 75 RF Circuit Design – by Chris Bowick A new edition of this classic RF NEW LOW PRICE!design text - tells how to design and integrate RF components $ 74 into virtually any circuitry. Practical RF H’book – by Ian Hickman A reference work for technic90 ians, engineers, students and NEW LOW PRICE! the more specialised enthusiast. Covers all the key topics in $ 73 RF that you need to understand. $ ! Audio ! RF ! Digital ! Analog ! TV ! Video ! Power Control ! Motors ! Robots ! Drives ! Op Amps ! Satellite siliconchip.com.au July 2009  87 Note that when the meter has lost power and starts again, the capacity reading will revert to 50% and may not be accurate until the next synchronisation, or until you manually declare the battery at full capacity by going to the BATTERY>Declare Full Now SubMenu. RLE compression Fig. 12: a screen grab showing the result of running the command “battcap.exe -i” to get information on the current settings. RLE (Run Length Encoding) Compression is used for data logging using an internal buffer. Run-length encoding works by substituting a consecutive run of similar readings by a single reading and a multiplicity. For example, the sequence 1.0, 1.0, 1.0, 1.0, 1.0 would be encoded as (1.0, 5) to save space. Depending on the set RLE Relative Error and the RLE Absolute Error, the compression is lossy or lossless. It is lossless if both the errors are set to 0. If not, the compression will be lossy and can achieve a good compression ratio. For example, if the relative error is set to 5%, the readings 1.0, 1.02, 1.03, 0.98, 0.99 will be encoded as (1.0, 5) since each is within ±5% of the first reading. This can save a lot of space in the local buffer allowing you to log a greater period of time. The trade off is of course accuracy. RLE is simple to implement and ideally suited to this type of logging application, where the readings are changing slowly over time. You can log up to four different readings at any time and each reading can be one of the following: battery Voltage, time remaining or charging, load current, charge current, circuit current, relay current, net current, capacity (AH) or capacity (%). To set up logging, you go to the LOGGING SubMenu. The logging data is stored locally and can be downloaded to a PC using the USB interface. Over time, this can become a useful set of data in monitoring the state of batteries to allow you to not only get peak performance but longest life. Conclusion Fig.13: this shows the result of running the command line “battcap.exe -x” – the real-time readings are displayed every second. 88  Silicon Chip As you can see, the SILICON CHIP Battery Capacity Meter has comprehensive features that will allow you to monitor the health of your battery and charger system. It is not difficult to build and can be easily calibrated using a digital SC multimeter (DMM). siliconchip.com.au Vintage Radio By RODNEY CHAMPNESS, VK3UG The Lyric 8-Valve Console From The 1920s This view shows the rear of the chassis, with the valve cover for the RF stages removed. All the valves were still in working order. Featuring no less than eight valves, the Lyric Model 70 broadcast-band receiver is an upmarket American-made set from the late 1920s. It’s a tuned RF design with single-knob tuning and a number of interesting design techniques. E XPERIMENTERS in the early days of radio produced some very ordinary looking receivers, mainly because they were forever changing things to improve the performance of their sets. Sometimes they were successful but mostly they just thought their set was definitely superior to their mate’s set. Those early sets were built on wooden boards and these were commonly referred to as “breadboards”. In fact, some were built on a real breadboards, siliconchip.com.au pirated from the kitchen! The breadboard-style layout was a very convenient method of construction during the early days of radio, as it made it very easy to continually change a set’s circuit or layout. As a result, experimenters’ sets used this style of construction for many years and even today the term “breadboarding” is used when building makeshift circuits. Breadboarding led directly to the so-called “coffin style” radios when companies began manufacturing domestic receivers in the early 1920s. In reality, these were breadboard sets with a nice wooden cabinet built around them, with a hinged lid on top that allowed ready access to the set’s internals. This also made it easy to occasionally tweak the circuit for better performance. Receivers in the 1920s were attractive pieces of lounge-room furniture and that certainly applied to many coffin-style receivers. However, as the 1920s progressed, most manufacturers quickly developed new methods for constructing their receivers. For a start, the top-of-the-line receivers needed to be more elegant in appearance. They also had to perform better and be easier to operate than the early 1920s sets. In particular, those early receivers commonly used several single-gang tuning capacitors, a regeneration control and a filament control (for volume), which made them difficult to tune and adjust. What was wanted by the average user was a receiver with just one tuning control and a volume control that had no time delay (as occurred with filament rheostats). They also wanted sets that didn’t whistle when the volume was increased above a certain level and they also needed to be more sensitive than the earlier 1920s models. In short, ease of use was the aim and people were prepared to pay more for sets that met that aim. Breadboard-style construction had reached its zenith during the 1920s. It was not easy to build relatively highgain receivers with multiple radio frequency (RF) stages without shielding between the stages. What’s more, these stages had to be close together in the later sets because people wanted single-knob tuning. Initially, single-knob tuning was achieved by mechanically coupling single-gang tuning capacitors via metal bands. These were then coupled July 2009  89 The unit features a 4-gang tuning capacitor, a large drum-type dial and a plug-in capacitor box. to a single tuning control. However, with the advent of multi-gang tuning capacitors, shielding became critical. To overcome this problem, manufacturers hit on the idea of using a metal chassis – basically a “cake tin” turned upside down. A metal chassis had several advantages over the traditional breadboard: (1) it was possible to produce a layout that worked well with no feedback; (2) the shields for the RF coils were effectively earthed to the chassis, which made them more effective; (3) cut-outs in the chassis could be standardised so that assembly was easier to manufacture (and therefore less costly); and (4) more components could be used as they could be fitted both above and below the chassis while still retaining accessibility. The downside was that many servicemen initially didn’t like the idea of working on both sides of the chassis because the concept was foreign to them. The same sort of attitude initially greeted PC boards during the 1960s. The Lyric Model 70 The Wurlitzer Company made many magnificent organs over many years but what is not so well known is that the company also dabbled in radio manufacture during the 1920s and early 1930s. In particular, the radios were made by the All-American Mohawk Corporation which Wurlitzer controlled. Once such unit was the Lyric Model 70, which is a very interesting set from the 1920s era. The unit featured here is owned by Mark and has been overhauled by Marcus, both fellow enthusiasts in our local vintage radio club. In fact, the chassis was Above: the dial has both wavelength and kilocycle markings, while the Tuning and Volume controls are mounted directly beneath the dial escutcheon. The toggle switch in the centre is the On/Off control. Left: the iron-cored chokes, the speaker transformer and the electrodynamic speaker are all attached to each other to form a single assembly. This assembly is connected via a cable and plug to the chassis. 90  Silicon Chip siliconchip.com.au Another view from the rear of the chassis, this time with the perforated valve steel cover (for the RF valves) in place. The boxes at the back house the interstage audio transformers. regularly brought to club meetings as the restoration progressed, to discuss any problems that had occurred along the way. The set was originally imported from America and has been operating via a 240V to 110V isolation transformer for most of its life. In fact, the person who originally owned it must have been quite wealthy, as a set of this calibre was a top-shelf model in its day. The set has also obviously been well looked after because its cabinet is still in very good condition. It was initially cleaned and then the inside brushed out with linseed oil thinned with mineral turps. A commercial furniture restorer was then applied to the outside using a soft rag. The views from both the front and back show that the manufacturer took pride in the appearance of this set. The dial escutcheon is of similar style to the better sets of the era and has both wavelength and kilocycle markings. The ornate Tuning and Volume control knobs are mounted directly under the escutcheon, while the toggle switch in the centre is the On/Off control. The cabinet is solid and the finish on the timber is good, with no short siliconchip.com.au cuts in the making of this cabinet. It is definitely a 2-man job to shift, as the cabinet and chassis combined are quite heavy. In fact the speaker assembly and the chassis weigh in at 6kg and 12.5kg respectively, which the cabinet adding to that. Circuit details The Lyric Model 70 is an 8-valve TRF (tuned radio frequency) receiver, designed to be powered from 110V AC. It has a number of features that were quite cutting edge for the era plus a few other features that, while interesting innovations, were really not practical in the long term. Fig.1 shows the circuit details. As can be seen, the antenna connects to the primary of the first RF tuned circuit. It also connects to a 12kΩ rheostat (R9) that gradually shorts out the antenna as it is rotated and forms part of the volume control network. Following the antenna, the signal is fed to the first tuned circuit where it is amplified by a 226 triode. The resulting signal on the plate of this valve is then fed via a second tuned circuit to another 226 triode where it is further amplified. A third tuned circuit and RF amplifier stage, again based on a 226 triode, follow. From there, the signal is fed via a fourth tuned circuit to a 227 triode detector stage. This has an audio transformer connected to its plate circuit (approximate step up ratio: 1:3) and the secondary of this is connected to a second 227 audio stage. The output of this stage is then fed through another audio step-up transformer to the grid of a 250 audio output stage. Finally, the audio output stage drives the loudspeaker via a speaker transformer. Interesting points There are a number of interesting features in the RF amplifier stages. First, each RF triode stage is neutralised using neutralisation capacitors that are mounted on the 4-gang tuning capacitor – see photo. These are adjusted during manufacture (via three screws along the bottom edge) so that the receiver is stable under all conditions with the volume control set at maximum. Another unusual feature of the 4-gang tuning capacitor is the method used to achieve tracking across the July 2009  91 Fig.1: the circuit features three tuned RF stages based on 226 triode valves. The amplified RF signal is then fed to a 227 detector stage, after which the audio passes through a second 227 stage and then via a transformer to the grid of a 250 audio output stage. A 280 valve functions as the rectifier, while the remaining 226 triode provides the bias for the 250 audio output stage. cuits to track would have been quite a task and certainly not one for the faint-hearted to attempt. As mentioned above, rheostat R9 progressively shorts the antenna signal and functions as the volume control. This control also has a second section which is connected to capacitor C2 in the plate circuit of the first RF stage. In operation, R9 and C2 progressively detune and partially short out the signal in the plate circuit to increase the effectiveness of the volume control. Another interesting feature is the filament supply arrangement. The first three stages have their filaments fed from a 1.5V line and they have a centre-tap resistor (R2) wired across the filament line. This was known as a “humdinger” and its function was to reduce any hum that may be induced from the filaments into the signal path. A resistor from the centre tap of this “humdinger” to the chassis provides bias for these stages. The detector and the first audio stage also have a “humdinger” (R4) across their 2.5V heater line to null out hum that could affect the audio signal. These are the only two indirectly heated valves in the receiver. The centre tap of this “humdinger” goes to the same bias resistor used for the 226 valves. The audio output stage uses the rather large 250 valve. It is fed from its own 7.4V filament line, and once again it has a “humdinger” across the filament line to chassis. The 250 is a low-gain valve with a gain of less than four. It also requires quite a high bias voltage, which can be as high as -84V. However, in this receiver a bias of only -52V to -56V is required. The bias for this stage is derived from a separate bias supply. This consists of a separate winding on the power transformer which is connected to a 226 valve wired as a diode, with a 0.5µF filter capacitor. This filtered is then fed through a resistive divider and the secondary of the driver transformer to the grid of the 250. HT supply broadcast band. As shown in the photo, there are another six adjustment screws positioned on the edge of the frame, three between the four gangs at the front and three more at the back. These screws are adjusted 92  Silicon Chip to shift a plate between each gang section, to alter the capacitance between the fixed plates and earth so that the tuned circuits could be adjusted to track correctly. There are no cores in any of the RF coils, so getting the cir- The HT supply is conventional with a full-wave 280 rectifier supplying the HT to all stages of the receiver. The line is filtered by two 13-Henry iron-cored filter chokes plus five capacitors. This receiver was built before electrolytic capacitors were available, so large paper capacitors of 2µF and 3µF siliconchip.com.au This under-chassis view shows the unit after restoration had been completed. The various plug-in modules have both advantages and disadvantages when it comes to servicing. were used instead. However, from the circuit, it’s apparent that the 280 rectifier is running close to its limits, with around 400V on the filament on load and a total HT current drain of around 70-80mA. Record player input The receiver has provision for a record player input but it’s doubtful that it would work. As shown on the circuit, the audio from the record player appears to be connected across the secondary winding of the RF tuned circuit feeding the detector. As a result, the audio signal would be effectively shorted out by this RF coil winding. Finally, the valve types used lost their prefix around 1930 and became known simply as the 26, 27, 50 & 80. Plug-in modules As shown in one of the photos, the iron-cored chokes, the speaker transformer and the electrodynamic speaker are attached to each other to form a single assembly. This assembly is connected via a cable and plug to the chassis. The plug is wired so that when it is disconnected, the power is automatically disconnected from the primary of siliconchip.com.au The 4-way tuning gang carries three variable capacitors along the bottom edge and these are used to neutralise each of the RF stages. In addition, there are six adjustment screws between the four gangs (three at the front and three at the back) and these are adjusted to ensure correct tracking across the band. the power transformer. This prevents the power supply from generating excessive voltage on the output of the rectifier when the assembly is unplugged. It also helps to protect a careless serviceman from electrocution. However, C11 is part of this assembly and is normally connected directly to the output of the rectifier. As a result, it would stay charged and could deliver a lethal shock if touched. The next plug-in module is the capacitor bank, consisting of 10 capacitors housed in a metal box (see photo). This was designed to be replaced as a single unit, meaning that if one became faulty the whole lot had to be replaced. This would have been expensive and July 2009  93 The chassis sits on a horizontal shelf in the top half of the cabinet, while the loudspeaker assembly is mounted in the bottom half and is connected via a cable and plug. Note the 240V to 110V step-down transformer at bottom right. as a result, plug-in modules like this didn’t find general favour at that time. Finally, the power transformer and the two interstage audio transformers are also plugged into sockets. Each of these is then secured to the chassis using four bolts. In short, this set had a number of modules that could easily be replaced if necessary, making it straightforward to service. Restoration The plug-in capacitor box contained a large number of faulty paper capacitors, which meant that a complete new assembly had to be made up. 94  Silicon Chip When the set first arrived on Marcus’s bench it was in a remarkably good condition considering its age. The cabinet and chassis only required a dust-out to make it easy to work on. However, he had no circuit diagram at that stage and this made things difficult. It is a complex set and it’s not easy to figure out what exactly is inside the plug-in capacitor and choke boxes. Despite having no circuit, Marcus immediately began restoring the set. His first task was to replace some poor-quality wiring, a legacy of some previous servicing. By contrast, the original wiring was found to be quite neatly done, even if it wasn’t always easy to follow. As mentioned previously, because it was designed for 110VAC, the set was powered via a 240V to 110V isolation transformer (not an autotransfomer). In the interests of safety, the original mains wiring was replaced to Australian standards. Next, the valves were removed and tested and all were found to be in good working order. That was fortunate as replacements would not be cheap and in any case, would be difficult to source. The only electrolytic capacitor in the set, which proved to be a ring-in, had dried out and was replaced. A Faraday shield had originally been fitted over the RF valves but this was now missing. As a result, a perforated metal shield was made up and painted the same colour as the chassis before fitting it into place. The capacitors were the next on the list. After examining the chassis, Marcus concluded that any leaky capacitors in the capacitor box were unlikely to cause problems with the valves, as transformers are used for the interstage coupling. Further checks also indicated that there were no shorts to earth or excess leakage to earth, so it would be safe to run the set for a short time in order to check voltages in the various stages. Well, it worked but it didn’t work very well. A heat-sensitive intermittent fault soon became apparent and there was also a fault with the volume control. Fortunately, a circuit diagram became available at about this time and this made troubleshooting so much easier, as it revealed the contents of the two “boxes”. First, the speaker/filter choke box was opened up and paper capacitor C12 across the speaker transformer primary replaced. All the other components in this box were in good order but the capacitors in the capacitor box were a different story. Removing the capacitors from this box was a difficult job as they had been set in pitch. In the end, a heat gun was used to soften the pitch, after which a carving knife was used to separate the capacitor assembly from the case. In short, it was a time-consuming and messy job. As expected, the 10 paper capacitors were all leaky and so had to be replaced. This was done by mounting much smaller replacement capacitors on two pieces of fibreboard (see photo). In particular, the 2µF and 3µF capacitors were replaced with mains-rated motor-start capacitors and the rest siliconchip.com.au ventional pots and is basically a dual rheostat rather than a potentiometer. It only has one gang but two separate tracks, which in this circuit are earthed via the wiper. The markings on the control, although appearing to relate to the resistance of the sections, are probably type numbers. It all confused Marcus before he obtained the circuit which revealed that each track has a resistance of 12kΩ. The unit was replaced with a dual-gang 10kΩ potentiometer. Finally, all the resistors were check­ ed and five out-of-tolerance component replaced. Testing The new capacitor bank was made up by mounting the parts on a couple of pieces of fibreboard and connecting them via flying leads. This assembly was then housed in the original box. The original capacitor bank is visible at top left. with mains-rated MKT and polyester types. The value of each capacitor was marked next to it on the fibreboard, to aid future servicing. As shown in the photo, the various leads were then soldered to the appropriate pins on the capacitor box plug, after which the box was plugged back into the set. By the way, the two capacitors marked C12 are used to tune the filter chokes for maximum filtering effect. However, the originals were meant to resonate on 120Hz ripple, not the 100Hz ripple with Australian mains. As a result, it was unnecessary to increase the values of the two C12 capacitors to achieve resonance in the filter network. The mica capacitors were tested and found to be in good order. Tracking down the intermittent It was now time to find the thermally-sensitive intermittent fault. The volume of the set would vary at a slow rate, indicating a problem with either a valve filament, a socket or some other part of the filament supply line. Careful testing revealed that the filament voltage on the lines to the 226 valves was varying and was low at around 0.9V AC. This problem was traced to the two “humdinger” centre-tap resistors on the filament lines to the 226s and 227s. These had riveted terminals which were making poor contact. They were cleaned and then soldered so that there was no discontinuity between the rivets and the riveted metalwork. When this was done, the filament voltage to the 226s was restored to the correct 1.5V AC. This markedly improved the set’s performance and it was now obvious that it would be worthwhile spending the money to get the speaker re-coned. This was subsequently done and it now has a high-quality foam-suspension cone which complements the quality of the rest of the receiver. The defective volume control was the next item on the list. This item is quite different in construction to con- It was now time to see what the receiver was capable of. There was no apparent instability in the RF sections so the neutralisation adjustments were left alone. The tuning coils and tracking adjustments were also left as they were, as the performance was very good and no adjustments were deemed necessary. The bias on the 250 audio output triode was checked and found to be in the design range of -52-56V. In operation, the receiver proved to have quite good selectivity and each station appeared in only one spot on the dial. It certainly had no trouble selecting stations that were relatively close in frequency to the local broadcasting stations. In summary, its performance is quite good for a set of its age and style and it would have been the focal point of any lounge-room it graced during the late 1920s and early 1930s. However, it would have become obsolete, at least in a design sense, by around 1935 due to rapid advances in technology and the increasing popularity of superhet receivers. That said, it still would have been a great set to have in the home and even today its performance is quite credible. It’s a set well-worth having in a collection, particularly as it is in SC such good working condition. Issues Getting Dog-Eared? Keep your copies of SILICON CHIP safe with these handy binders REAL VALUE AT $14.95 PLUS P & P Available Aust, only. Price: $A14.95 plus $10.00 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au July 2009  95 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 or send an email to silicon<at>siliconchip.com.au Faulty LED indication in Speed Alert I built the Speed Alert project as published in the November and December 1999 issues of SILICON CHIP. The kit was a dream to build and functions well except that LED1 (visual alarm) stays on permanently. I have checked all solder joints etc and cannot find any faults. It seems that there is ground potential on pin 6 of the PIC all the time. The audible alarm works every 10s (as it should) but is quite faint. (R. B., via email). • The alarm LED (LED1) is driven via the 5V dimmed supply at the emitter of Q4 through the 560Ω resistor and to pin 2 of IC1. If pin 2 is low then LED1 will light. Normally pin 2 is at 5V unless the alarm is on. The only way LED1 could be alight continuously is if there is a short to ground for pin 2 (or a low resistance to ground). Alternatively, check that LED1 is oriented correctly. 9V to 27V DC converter wanted I am interested in your DC-DC Converter, as published in the June 2003 issue. Its maximum output is 20V. My requirement is for a DC-DC converter which has a 9V input and a 27V output. Do you have a suitable circuit? (R. R., Rowville, Vic). • The DC-DC Converter can be altered to deliver 27V by changing the 1.2kΩ resistor in series with trimpot VR1 to 470Ω. Note that the output current would be limited to about 450mA. Help with old EA ignition circuit I have been using a design for a transistor ignition published in EA in February 1983. It has been installed on numerous vehicles and recently on a 1985 model Toyota Hilux. This circuit has been extremely reliable and has given no problems in the vehicles it has run. Recently, I had the main switching transistor fail (short circuit). Looking at the alternatives you have published over the years led me back to my original one as being easier to fix. But can I replace the BUX80, 2N6547 transistor originally used with one of the newer MJ10012 or MJH10012 Darlington transistors without any mods to the original circuit? If not, can you suggest any modifications to make it work? (C. L., via email). • The MJ10012 or MJH10012 can be used to replace the BUX80 but the old “Electronics Australia” Transistor Assisted Ignition circuit is not ideal for the MJ(H)1012 transistor as it draws Power Supply For Multimedia PC Amplifier I built the Multimedia PC Amplifier and Speakers (SILICON CHIP, October & November 1996) some years ago for use on an old 486 computer with ISA sockets. Recently I found a use for it again, using the line input from a set-top box and volume control via the STB remote in a TV set-up using a spare monitor I have. The set-up works well but the old 486 computer is noisy and really all I need is an appropriate power unit for the 12-0-12V supply and a suitable enclosure. I note the computer 12V 96  Silicon Chip supply is 6A and 0.6A – and my son has advised me that there is a much larger current required on the positive rail of the amplifier. Apart from using the computer, have you any suggestions as to a suitable power supply. (G. C., via email). • Your son is correct. The positive 12V supply rail will need to supply more than 4A peak when the amplifiers are running at full power. A computer power supply is still the best answer. These days they tend to be a lot quieter. more current than is necessary to drive the latter Darlington transistor. The 10Ω resistor at transistor Q4’s base should be a 1W type due to the higher voltage drop from base to emitter for the Darlington MJ(H)10012. Two of the 2.7Ω resistors driving Q4’s base could be removed since there is no need for the high base current with the Darlington. Concern over Nixie tubes in digital clock I refer to the Retro Nixie Clock in the July & August 2007 issues of SILICON CHIP. With the clock running permanently, what would be the predicted life of the Nixie tubes? Do they, after a period of time, simply “give up the ghost”? Would the clock’s “normal” life be 3, 4 or 10 years? (K. J., via email). • The life of a Nixie tube depends on the manufacturing quality, the way the tube is driven and the care with which they are handled. There is no definitive answer as to their life. We expect a good Nixie tube to last many years in the digital clock. We cannot give a precise estimate. If you are concerned, it would be wise to get some spares before the availability of these becomes scarce. Sourcing coils for the Theremin I have read the article on the Theremin (SILICON CHIP, August 2000) and I need information to get the variable coils. I have visited the websites for Mitsumi and Toko but I cannot select suitable coils for the Theremin. Can you help? (C. T., Santiago, Chile). • Mitsumi or Toko do not make the specified coils. You can obtain the correct coils from Jaycar Electronics (Cat. LF-1050). You would require three (3) of the LF-1050 coil packs to get the correct number of white-slugged cores. Contact www.jaycar.com.au Note that a revised version of this Theremin circuit was published in the March 2009 issue of SILICON CHIP. siliconchip.com.au External DAC For A CD Or DVD Player I cannot find any reference to DACs (Digital-to-Analog Converters) as used for hifi CD data conversion. These are available from hifi dealers but it’s a project that SILICON CHIP could consider. I have already built several hifi-based projects published by SILICON CHIP and a top-quality DAC would be great. Do you have any plans for such a project? (R. P, Horley, UK). • As we see it, there are only two reasons why you would use a separate DAC with an existing CD player: (1) the existing DAC in your CD player is audibly inferior or (2) you want to avoid any problems with hum induction or earth loops by using the digital output of your CD player. How to make front panels Have you ever described the process and materials used to produce the front panel labels of your projects. Alternatively, is there a website that you can point me to for information on the process that you use? (R. S., Burrill Lake, NSW). • We have published several articles on making front panels: (1) Making Front Panels For Your Projects (February 1999); (2) At Last – An Easy Way To Make Pro Panels (April 2002); (3) Restoring Old Dials, Front Panels And Labels (July 2004); and (4) Making Panels For Projects (July 2007). Incidentally, by far the easiest way to make a high-quality front panel these days is to produce it using any of the PC drawing/graphics packages (we use CorelDraw), print it out on good quality paper and then laminate it. A4 laminators are now very cheap – we’ve seen them for as low as $29.95! No real need to vary speed control frequency I have built four of the 12-24V high current motor controllers for use in work platforms in temperature-controlled, horticultural tunnel houses. The units drive a 24V DC motor/ siliconchip.com.au Neither of these issues are significant for the vast majority of users and in any case, in spite of all the subjective rubbish written in UK hifi magazines, most people would be unable to hear any difference between the DAC output of a typical good-quality CD player from Sony, Yamaha, Marantz, Denon etc and any external DAC, no matter how pricey it may be. However, if you are using a DVD player to play your CDs, even a good-quality brand may be notably inferior to the abovementioned CD players. In fact, in our experience, all DVD players have significant problems when used in conjunction with a good-quality home hifi system. This is firstly because they all gearbox. The units all work well. My question is why do I need to alter the frequency? (B. B., via email). • For most applications there will be no need to alter the frequency of the speed control. In fact, for most applications you can leave all the standard (default) settings unchanged. However, if you have a motor or gearbox which is noisy at a particular frequency, then you have the option to change. Also, depending on the motor’s inductance, you may find that it responds better to a higher or lower drive frequency. Running a caravan from solar power I have bought a new caravan with a 12V system and in-house battery. I use an electric razor and when on 12VDC will use a 12V-to-230V AC inverter. I also thought the inverter would come in handy for charging a video camera and a still camera battery. The two chargers involved are both switchmode units and I have been told that this type of charger should only be connected to a sinewave supply; never to a modified square wave supply. Do you have any thoughts on this? I have a 50W solar cell which has an output of a little over 3A, which I would like to use (if off mains supply) to top up the battery (a 95A.h deepcycle type). Do I really need a charge use double-insulated switchmode power supplies. These can inject significant hum into a hifi system as well as high-frequency frizzle, in some cases. Secondly, the DAC and audio output stages used in the majority of DVD players typically give inferior or even poor audio quality. Ultimately, an external DAC with SPDIF or TOSLINK connection is the way to go if you want hifi audio from a DVD player. In fact, the TOSLINK connection is the best because it eliminates all problems with hum induction or hum loops. With this in mind, we plan to publish a high-quality DAC with SPDIF and TOSLINK inputs, starting with the August or September issue. controller on a system as small as this? If so, why? I don’t think it would overcharge the battery at a maximum of 3A, do you? Has SILICON CHIP ever published a construction article for a charge controller? If so, would you tell me which edition it was in? To lessen the load on the battery, I have constructed and fitted a number of LED lights in parallel to the fluorescent/incandescent lights already fitted, with a total battery drain of only 1A compared to about 10A! What with solid-state hard drives and LED lighting, the electrical and electronics scene sure is changing. (N. W., via email). • We doubt whether you would need a controller. We would be inclined to just hook it up and then monitor the battery over a period to see how it goes. Ozitronics Tel: (03) 8677 1411 Fax: (03) 9011 6220 Email: sales2009<at>ozitronics.com 4-Channel Temperature Monitor and Controller Features 4 temperature inputs (DS1820) and 4 relays for output control. Simple text commands via RS232 to read temperature and control relays. Can be controlled by terminal program or via free Windows application. Pluggable screw terminals for sensors and relay outputs. K190 $104.50 More kits and all documentation available on website: www.ozitronics.com July 2009  97 Misconceptions About Ions In Salt Solution I was just reading your article entitled “Test The Salt Content Of Your Swimming Pool” (SILICON CHIP, December 2008) and thought about using your technique at home. I was investigating further when I found a couple of articles stating that using an ohmmeter for testing will cause a molecular change within the salt solution due to the test current being DC, thus making the test invalid. I include a link to of one of the articles I read concerning this: http://blea.ch/ wiki/index.php/PPM_Meter I am now quite confused about the whole situation. (G. F., Kurralta Park, SA). • The quote you are referring to is as follows: “Because they pass DC current thru the probes and you cannot measure conductivity of salts with DC current because it will rip the molecules apart, and since the molecules are what conducts the electricity you get a constantly changing reading that is useless. Overcome this by using an AC signal. If the frequency is high enough (>1kHz it seems) the molecules don’t have time to move apart before they are pulled in the opposite direction. Sort of like how high DC current will throw a person off of it, where as AC forces them to hold on and get shocked to death or something.” As with so much stuff on the internet, this is utter nonsense and indicative of the high level of ignorance of all things technical by most people. In fact, when you dissolve salt into solution, the molecules of salt become sodium (Na+) and chloride (Cl-) ions and it is precisely because of these ions that electric current can pass through the solution. This is just basic chemistry. However, the designer of this PPM circuit is on the right track in advocating the use of AC rather than DC to make the measurement. But it is has nothing to do with “ripping molecules apart”. The reason for using AC rather than DC is to avoid electrolysis of the measuring electrodes. In effect, the electrodes would be eaten away over a long period of time. That is why commercial TDS/PPM meters generally use carbon electrodes and an AC test voltage. If DC was used If you do want to build a controller have a look at the December 1999, March 2002 and February 2008 issues. We have also published a lot of solarrelated items in Circuit Notebook. Your chargers should be OK running from a modified square-wave inverter. This Australian supplier has various switches available. You would probably need to set the sensor to about 5 psi. Pressure switch wanted for pool pump circuit I built the Remote Control Extender (SILICON CHIP, October 2006) and it works well with all my TVs & VCRs but it won’t work on my Panasonic DMRXW300 DVD recorder. I’ve used various IR receivers out of modern VCRs and it will only work intermittently. Can you tell me where to source the TSOP4136 IR receiver? Altronics and Jaycar don’t know if theirs is a TSOP4136 (Jaycar ZD-1952). Also Altronics supplied TLC555 for the 7555 timers. Are these OK? (E. L., via email). • The IR receiver supplied with the kits from both Jaycar and Altronics for this project is the TSOP4136. The Jaycar ZD-1952, however, is not a TSOP4136 and is not suitable for use with the extender as it will not work I have a query regarding the pressure switch used for the Smart Pool Pump Control circuit featured in the Circuit Notebook pages of the October 2008 issue. Would you have any suggestions as to who would stock them? Thanks for producing such a highquality magazine every month with excellent projects and interesting articles. (P. B., Richmond, NSW). • Farnell (www.farnell.com.au) sell pressure sensors (eg, Cat. 723-0461) but these are expensive. You may be able to obtain a suitable pressure sensor from www.baccara.com.au/ pressure-switches.shtml 98  Silicon Chip Infrared remote extender query with carbon electrodes, it would lead to electrode polarisation and high resistance readings. In fact, meters which purport to measure TDS (total dissolved solids) are a bit of a joke anyway because they can only measure those solids which dissolve to form an ionic solution. For example, they cannot measure the amount of sugar in a solution because sugar does not break up into ions. And while the designer stresses the importance of a nice clean sinewave for the test waveform, that is not strictly necessary. All you need is an AC waveform with a 50% duty cycle and no DC component. In other words, a square or sawtooth waveform would do just as well. In fact, the simple method we described in the December 2008 issue is quite valid. However, as pointed out by a correspondent in the Mailbag pages of the February 2009 issue, using measuring spoons for a quantity of salt can be inaccurate and you are better off using digital kitchen scales for making the solution. with the Foxtel digital decoders. The standard IR receiver sold by Altronics also is not the TSOP4136. Farnell (www.farnellinone.com. au) do sell the TSOP4136 and other types of IR receivers. Either the TSOP­ 4138 which operates at 38kHz or the TSOP1133 which operates at 33kHz may be more suited to your DVD recorder. The Texas instruments TLC555 is equivalent to the Intersil 7555 timer. Both are the CMOS types and are suitable. The LMC555CN from National Semiconductor is also suitable. Secondhand batteries are a risky proposition After reading an article in your magazine that stated it is better to plan ahead when purchasing batteries for solar systems, I have spent quite a lot of time looking on eBay for some large batteries. I have run into some 12V 150Ah SLA batteries and I wonder what you think. They are secondhand, siliconchip.com.au eight years old, with a design life of 15 years. Do you think they are worth buying for a DIY solar system, considering the price? (C. G., via email). • You have no way of knowing what you are getting when you buy secondhand batteries, from eBay or any other source. Unless you could borrow them and do some careful capacity tests over several charge/discharge cycles you could simply be buying some very heavy garbage. The vendor may be quite genuine but you have no way of knowing that. In any case, the vendor himself may have no way of knowing or measuring the performance of his batteries. RF loop explanation I was wondering if someone might be able to help me. When I look at advertisements for SD and HD-STBs, they sometimes refer to “RF-In” and “RF Loop Out”. What does “RF Loop Out” mean? Is it just passing through the unprocessed input signal to the output? Why don’t any of the current breed of STB take the digital RF input and then provide, along with the other output formats, an analog RF output signal? The lack of such a signal means that another device (ie, RCA-to-analog RF modulator) is required. (P. M., Karabar, NSW). • The RF loop is exactly the same as that on VCRs and DVD recorders, where you have an “Antenna in” and “Antenna out” socket to feed your TV. One reason why STBs do not have an analog RF output is that it would defeat the purpose of the STB itself. The picture quality available via the composite video, component video or HDMI outputs is much better than Notes & Errata 6-Digit GPS Clock, May 2009: a 100µF 16V capacitor has been omitted from the circuit on page 22. It is shown on the PC board overlay and is adjacent to transistor Q14. 10A/230V Motor Speed Controller, May 2009: the references to IC1a & IC1b and to IC3a & IC3b in the text should be swapped to agree with the block diagram on page 39 and circuit diagram on page 40 (the references to IC3a & IC3b for the current monitoring circuit description are correct). can be provided via a modulated RF output. Tank water level display I recently built the Tank Water Level Display (SILICON CHIP, November & December 2007) and the base station to go with it. My problem is that they refuse to talk to each other. I have replaced both transmitters and receivers and tested the new ones that I put in (both were good). Now if I connect a 4-ohm speaker to the data and earth pins on the transmitter and press the check button, the speaker emits a healthy blurt, so it appears to have a signal going to it. I don’t get any noise if I connect the speaker to the base station receiver data and earth pins. Now bear in mind that to test the transmitter and receiver I just connected 5V to the “Ve” and “Data” pins of the transmitter module and then monitored whether any signal came out of the data pin on the Preamplifier for Speed Controller, Circuit Notebook, May 2009, page 35: the fourth paragraph in the righthand column makes reference to Q1 & Q2 forming a simple 2-transistor amplifier. This should refer to Q1 & Q3. 2-Channel UHF Mains Switch, May 2009: on page 82, the +12V rail supplying the junctions of the 47Ω resistors and LED1 via Rs# should come from the cathode of diode D1, not the cathode of D2. receiver module. I got a reading of 4.5V. The only thing I can think of is that the transmitter module might not be getting any voltage before the data is sent to it but I have no way of testing this. If you have any ideas, it would be greatly appreciated. (B. W., via email). • For the base station to receive data from a tank meter, the base station must be set to receive data from that tank. For example, for tank 1 data, the base station needs to be set to receive tank 1. Setting up for this is described in the base station article. Similarly, the encode setting must be the same for both the tank meter and the base station in order to receive and display the detected data. Note that if the transmitter and receiver are too close when testing the units (less than about two metres apart), the receiver will not detect the data correctly. Note also that the transmitter and receiver both require an antenna as described to obtain adSC equate transmission range. 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. siliconchip.com.au July 2009  99 ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. PRACTICAL GUIDE TO SATELLITE TV By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To siliconchip.com.au JCall uly 2009  101 Use your PayPal account www.siliconchip. (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 Place com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP CLASSIFIED ADVERTISING RATES Advertising rates for these pages: Classified ads: $29.50 (incl. GST) for up to 20 words plus 85 cents for each additional word. Display ads: $54.50 (incl. GST) per column centimetre (max. 10cm). Closing date: 5 weeks prior to month of sale. To book your classified ad, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or fax (02) 9939 2648, or post to Silicon Chip Classifieds, PO Box 139, Collaroy, NSW, Australia 2097. _____________ _____________ _____________ _____________ _____________ Looking for real performance? • Learn about engine manage­ ment systems • Projects to control nitrous, fuel injection and turbo boost Intelligent systems TURBO BO OST engine • Switch devices according to signal frequency, temp­ erature & voltage • Build test instruments to check fuel injector duty cycle, fuel mixtures and brake & temperature From the publish ers of turbo timer I SBN 09585229 9 78095 8 4-4 5229 46 $19.80 (inc GST) NZ $22.00 (inc GST) _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ & nitrous fuel controllers How management works Price: Aust. $A19.80 plus $A10 P&P ($A12 P&P NZ; $A18 P&P elsewhere) – see the order form in this issue or www. siliconchip.com.au for ordering details. _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my o Visa Card   o Master Card Card No. Signature­­­­___­­­­­­­­__________________________ Card expiry date______/______ Name _________________________________________________________ Street _________________________________________________________ Suburb/town ______________________________ Postcode______________ Phone:______________ Fax:______________ Email:___________________ 102  Silicon Chip FOR SALE HP/Agilent 8920/8921/8924 “RF Tools” PC Connectivity Software. Antenna/ filter tuning, cable fault location, RF spectrum recording, signal-strength logging, screen capture. www.measurement.net.au RCS RADIO/DESIGN is at 41 Arlewis St, Chester Hill 2162, NSW Australia and has all the published PC boards from SC, EA, ETI, HE, AEM & others. Ph (02) 9738 0330. sales<at>rcsradio.com. au; www.rcsradio.com.au AUSTRALIAN WASHING Machine Repairs by L. Alford (+180 A4 page book) $40 + p&p. 0419 350 106. www. users.bigpond.com/lalf LEDs! Nichia, Cree and other brand name LEDs at excellent prices. LED drivers, including ultra-reliable linear driver options. Many other interesting and hard-to-find electronic items! www. ledsales.com.au TECH REPAIRS SERVICE MANUALS www.techrepairs.org – thousands of siliconchip.com.au C O N T R O L S Tough times demand innovative solutions! ELNEC IC PROGRAMMERS High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP CLEVERSCOPE USB OSCILLOSCOPES SPK360 3/5/06used1:10 PM world-wide Page 1 Made in Australia, by OEMs splat-sc.com 2 x 100MSa/s 10bit inputs + trigger 100MHz bandwidth 8 x digital inputs 4M samples/input Sig-gen + spectrum analyser Windows 98/Me/NT/2k/XP IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 20 years experience! HI-FISPEAKER REPAIRS GRANTRONICS PTY LTD www.grantronics.com.au Specialising in UK, US and Danish brands. Speakerbits are your vintage, rare and collectable speaker repair experts. Foam surrounds, voice coils, complete recone kits and more. Original OEM parts for Scan-Speak, Dynaudio, Tannoy, JBL, ElectroVoice and others! CIRCUIT WIZARD A revolutionary new system that combines circuit design, PCB design, simulation & CAD/ CAM in one complete package for your pc. om: e demopftrs.com e r f a d a Downloew-wave-conce www.n To see the Standard s between difference Ideal for Schools, TAFEs, Hobbyists & Business Circuit Wizard Standard – $225* *inc GST & Circuit Wizard Pro – $434*post in Aust. 555Electronics 19 Kensington St, Clovelly Park, SA 5042 Tel (08) 8277 8936 email: bwigley<at>senet.com.au www.555electronics.com.au VIDEO - AUDIO - PC DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters tel: 03 9647 7000 www.speakerbits.com downloadable service manuals for all brands, makes and models including PDP, LCD, VCR, DVD, CTV, Vintage Radio, Laptops, Monitors, Vacuum Cleaners, Washing Machines, Dryers, Fridges and many more. An absolute must have website for any Tech! PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au POSITIONS VACANT POSITION AVAILABLE for school leav­ er / elect cert tech student / university undergrad genuinely interested in electronic hardware development. Penrith, Sydney. www.furzy.com WANTED CUSTOMERS: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects including Drew Diamond. 27 The Mall, South Croydon, Melbourne. (03) 9723 3860. electronicworld<at>optusnet.com.au siliconchip.com.au atures’. s click on ‘fe nal version & Professio distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates SPK360 YOUR EXPERT SPEAKER REPAIR SPECIALISTS NEW! WANTED: EARLY HIFIs, AMPLIFIERS, Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Tannoy, Goodmans, Wharfedale, radio and wireless. Collector/ Hobbyist will pay cash. (07) 5471 1062. johnmurt<at>highprofile.com.au MD12 Media Distribution Amplifier QUEST ® Quest AV® HQ VGA Cables KIT ASSEMBLY KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com VGA Splitter VGS2 AWP1 A-V Wallplate Come to the specialists... QUESTRONIX ® Quest Electronics® Pty Limited abn 83 003 501 282 t/a Questronix Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au Issues Getting Dog-Eared? Keep your copies safe with these handy binders Available Aust. only. Price: $A14.95 plus $10 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. REAL VALUE AT $14.95 PLUS P&P Buy five and get them postage free! July 2009  103 Do you eat, breathe and sleep TECHNOLOGY? Opportunities exist for experienced Sales Professionals & Store Management across Australia & NZ Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 60 stores in Australia and New Zealand. Due to our aggressive expansion program we are seeking dedicated sales professionals to join our retail team to assist us in achieving our goals. We pride ourselves on technical expertise from our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do:  Knowledge of core electronics, particularly at a component level  Retail experience, highly regarded  Assemble projects or kits yourself for your car, computer, audio etc  Have energy, enthusiasm and a personality that enjoys helping people  Opportunities for future advancement and development  Why not do something you love and get paid for it? Please email us your applicaton & CV in PDF format, including location preference. We offer a competitive salary, sales incentive and have a generous staff purchase policy. Applications should be emailed to jobs <at> jaycar.com.au Jaycar Electronics is an Equal Opportunity Employer & actively promotes staff from within the organisation. into RF? DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom There’s something to suit every radio frequency fan in the SILICON CHIP reference bookshop RF Circuit Design – by Chris Bowick A new edition of this classic RF design text - tells how to design and integrate RF components into virtually any circuitry. $ 75 Practical RF H’book – by Ian Hickman A reference work for technicians, engineers, students and the more specialised enthusiast. Covers all the key topics in RF that you $ need to understand 90 Practical Guide To Satellite TV – by Garry Cratt The reference written by an Aussie for Aussie conditions.Everything you need to know. $ 49 You’ll find many more technical titles in the SILICON CHIP reference bookshop – see elsewhere in this issue 104  Silicon Chip WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au Silicon Chip Circuit Ideas Wanted Do you have a good circuit idea? If so, sketch it out, write a brief description of its operation & send it to us. Provided your idea is workable & original, we’ll publish it in Circuit Notebook & you’ll make some money. We pay up to $100 for a good circuit idea or you could win some test gear. Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Advertising Index 555 Electronics............................. 103 Agilent Technologies......................... 9 Alternative Technology Assoc......... 87 Altronics..................................... 74-77 Amalgen Technologies.................... 11 Amateur Scientist CDs.................... 69 Dick Smith Electronics............... 24-25 Emona Instruments......................... 10 Farnell............................................... 3 Furzy Electronics.......................... 103 Grantronics................................... 103 High Profile Communications........ 103 Instant PCBs................................. 103 Jaycar............................IFC,49-56,104 Keith Rippon................................. 103 LED Sales..................................... 102 Lindsay Alford Appliance Repairs. 102 Measurement Innovation.............. 102 MicroZed Computers...................... 41 Mornsun............................................ 8 Oatley Electronics......................... IBC Ocean Controls............................... 43 Ozitronics........................................ 97 PCBCART......................................... 6 PCBCORE...................................... 11 Quest Electronics.......................... 102 RCS Radio.................................... 102 RF Modules...........................OBC,104 RMS Parts....................................... 23 Rohde & Schwarz............................. 5 Sesame Electronics...................... 103 Silicon Chip Binders...................... 103 Silicon Chip Bookshop........... 100-101 SC Performance Elect. For Cars... 103 Silicon Chip Order Form................. 37 Silicon Chip Subscriptions.............. 19 Siomar Battery Industries................. 7 Soundlabs Group.............................. 4 Speakerbits................................... 103 Splat Controls............................... 103 Switchmode Power Supplies........... 45 Tech Repairs................................. 102 Tekmark Australia............................. 6 Truscotts Electronic World............. 103 Wagner Electronics......................... 47 Worldwide Elect. Components...... 104 Xyber Data Recovery...................... 33 PC Boards Printed circuit boards for SILICON CHIP designs can be obtained from RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0331. siliconchip.com.au K270 - TUBE PREAMPLIFIER KIT This low cost tube preamplifier lets you experience tube sound. The K270 is based on two low power consumption Raytheon JAN6418 sub-miniature pentodes. Kit is comes with PCB & onboard parts [K270] K272 TUBE HEADPHONE AMPLIFIER KIT Based on two low power consumption Raytheon JAN6418 subminiature pentodes. Kit inc PCB & onboard parts [K270] $29 K265 DIGITAL PANEL METER INTERFACE KIT ring onito s or m system f l a Ide power r sola $16.50 one kit can power 2 meters. K207A UP / DOWN INVERTER / LED DRIVER WITH EXPERIMENTERS LED ARRAY PCBs. This kit is designed to up or down invert to supply LEDs. It is suited to our 10mm 1/4W LEDs. $9.90 K269 MULTIPURPOSE HALL EFFECT INTERFACE KIT This Hall effect based kit should be suitable for many uses. The combination can be used to measure magnetic field strength, for shaft enA section coders, to measure of the PCB rotational speed (RPM), can be snapped etc. The kit includes 2 off & wired to the small rare earth main PCB for remote use. (Neodymium) magnets. 12VDC MOTOR AND SPEED CONTROLLER KIT PACKAGE DEAL This package includes our popular and powerful K252 speed controller kit (10-36V <at> 20A) and a compact yet powerful DC motor. This motor was designed for automotive use. It has a connection on the rear for a hose to apply positive pressure to stop dust or water ingress. Measures 60mm Dia. X 110 overall. Special introductory price of $29.00 [K252M2] TEST EQUIPMENT (USED) HP 8640A SIGNAL GENERATOR [1AZ79] $599, *** HP 8350B SWEEP OSCILLATOR + 86250D0 + 83525A [1AZ86] $3,400, *** HP 3575A GAIN PHASE METER 1Hz - 13 MHz [1AZ83] $849, *** SWISS THOMMEN 3B4 GEODESIC SURVEYING ALTIMETER +/-2M [1AZ91] $515.00, *** BWD MINI-LAB MODEL 603B 0.1Hz-1MHz FUNCTION GENERATOR [1AZ92] $245.00, *** SOLARTRON SCHULMBERGER 4940 RF MULTIPLEXER [1AZ99] $100.00, *** TRANSMISSION IMPAIRMENT MEASURING SET [ZC0517] $200.00. MORE ON OUR WEB SITE (USED) 24V-700VA SINE WAVE INVERTER / UPS Y L N O 9 4 1 $ These UPS's are used but in excellent condition. They use a DB9 serial cable to connect to a computer. They have genuine Sine Wave output, 4 IEC mains outlets & 1 IEC mains input. The front panel includes a LED bargraph battery condition indicator. They use 2 standard 12V-7AHr batteries in series which may need to be replaced. Can be used without a computer as they can be simply turned On or Off by pressing the front panel buttons. Software & manuals can be downloaded from the manufactures web site. We supply the UPS and one IEC mains lead only. The custom DB9 lead is available but not from us. However it is simple to make, see the connection diagram below. [1UPS] $149.00. ABOVE UPS WITH NEW BATTERIES [1UPSBP] $179.00 BACK IN STOCK K271 - 26" - 24V - 200W ELECTRIC BIKE CONVERSION KIT Detects pedalling and automatically assists the rider and/or can be controlled with a conventional throttle. Batteries not included. PARTS LIST 1 X wheel & motor assy, 1 X controller, 1 X pedal, sensor, 1 X pedal sensor disk, 1 X throttle, 2 X handbrake levers [K271] $249.00 PRECISION TRUE RMS AUTORANGING 5½ DIGIT MICROVOLT DMM K Unused Keithley TOC model 197 TRUE ED S ICE T I M I RMS Digital RY L ANCE PR M u l t i m e t e r. I t VE R includes a RF CLEA probe making it useful for 1mV-1/100V (with the divider inc.) Includes an IEE-488 interface option and analogue out. Inc. a Quick Reference Guide, Users & Service manual for the DMM, and the IEEE Interface. Accessories: Multimeter leads. SDRF-28 RF Probe and tip set. SDFT-50 50ohm feed-through termination. SDD-100 100:1 divider. [1AZ76] $479.00 MONO-CRYSTALLINE SOLAR PANELS UNFRAMED 6W SOLAR PANELS These panels are fully sealed but have no aluminum frame. 290 X 250 X 4mm Power: 6W O/circuit: 20.9V S/circuit: 0.39A Maximum: 0.36A Max. Sys.: 1000V [SP6UF] $50 BACK IN STOCK! LARGE DC MOTORS (GEARED & DIRECT DRIVE), SPEED CONTROLLERS, WHEELS, THROTTLES, SPROCKETS AND CHAINS. SEE OUR WEB SITE. These panels are waterproof, aluminium framed and covered with tempered glass. Connections are made to the screw terminals that are inside the small box at the rear of the panel. 8W SOLAR ARRAY Includes two 4W 6V monocrystalline solar panels. Connect in parallel for a 6V - 8W array Or connect in series for 12V - 8W output, Peak: 4W ea. Open Circuit: 10.6V Short Circuit: 0.5A Max.: 8.5V, Max.:0.47A, 254x294x23mm, 900g [2XSP4W6] $70.00 20W-12V MONOCRYSTALLINE SOLAR PANEL Peak: 20W, Open Circuit: 21.5V, Short Circuit: 1.3A, Max.: 17.2V, Max.: 1.15A, 639 x 294 x 23mm 2.5kgs [SP20] $155.00 100W SOLAR PANEL ARRAY & REGULATOR KIT This 100W solar array inc. 5 X 20W-12V (As above) monocrystalline solar panels, a 12V/24V regulator kit & weatherproof box for the kit. [ARRAY] $660.00 Note: these panels may vary slightly from photographs. www.oatleyelectronics.com Suppliers of kits and surplus electronics to hobbyists, experimenters, industry & professionals. Orders: Ph ( 02 ) 9584 3563, Fax 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 July 2009  105 major credit cards accepted, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 OR www.oatleye.com siliconchip.com.au SC_JUL_09