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SILICON CHIP AUGUST 2008 ISSN 1030-2662 08 9 771030 266001 PRINT POST APPROVED - PP255003/01272 8 $ 50* NZ $ 9 90 INC GST ALL-NEW 200W AMP MODULE INC GST Astonishingly low distortion State-of-the-art design Uses new 5-pin ThermalTrak transistors BELIEVE IT OR NOT . . . This 3D heart model was printed, in colour, on an inkjet printer! See the full story inside . . . LISTEN IN TO JUPITER! BUILD THIS RECEIVER FOR NASA’S RADIO JOVE PROJECT siliconchip.com.au (It’s much cheaper than the US import kit!) August 2008  1 EVERYTHING FOR THE ELECTRONICS ENTHUSIAST Wireless Fun RC Mini M*A*S*H Helicopter This is our smallest readyto-fly infrared remote control helicopter. It is made of durable plastic and is ideal for indoor use. • 20 min charge time for 8 min flying time • Requires 6 x AA batteries • Helicopter 135mm long • Suitable for 8yrs+ $ 29 95 Cat: GT-3260 RC 1:43 Scale Turbo Mercedes C-Class DTM This little wonder is a 1/43rd scale factory endorsed replica of one of the most stylish vehicles available. It features full functioning controls including forward, back, left, right & turbo. • Requires 6 x AA batteries See in-store or on-line for our full range of remote controlled cars. $ ENTERTAINMENT AM/FM World Band Receiver A truly portable world radio that is designed for functionality and ease of use. It covers the standard AM/FM bands as well as the short wave bands from 2,300kHz to 22,000kHz. The tuner uses phase locked loop (PPL) technology which ensures rock-steady, drift free reception. This is an excellent radio that will perform well for years to come. • Approx 190mm wide • Requires 2 x AA $ 95 batteries Cat: AR-1745 See our website for a full list of features 49 3.6V Cordless Screwdriver with Pivoting Handle 22 95 Cat: GT-3294 V8 Alarm Clock Wake up to the realistic V8 engine-sounding alarm. Easy to use and attractive in design, it is sure to be a hit with any motoring enthusiast young or old. • Realistic pedals for demo and clock controls • Spinning brake disc when the alarm is activated $ 95 • Clock 120mm dia. Cat: AR-1769 • Requires 3 x AA batteries 24 Nothing beats the convenience of a cordless screwdriver. This one is even better because of its pivoting handle which folds from straight to an angle position for better grip. Includes charger. • 230RPM • 6 torque settings This pre-programmed remote operates the main functions of your TV and features large, easily read buttons. The unit is great for people with big hands or who find tiny buttons & small writing difficult to cope with. • Requires 2 x AAA batteries • 130mm long $ 14 95 Cat: AR-1703 Solar Mobile Phone Charger Simply charge the internal battery via the sun, USB port or mains adaptor for truly portable energy that allows you to charge your phone and other digital devices wherever you are! Keep the battery topped up using free power from the sun. • Li-ion battery $ 95 • 1000mAh capacity • Suits most phones Cat: MB-3588 • Folded size - 120(L) x 17(W) x 62(H)mm Was $69.95 $15 54 $ 11 95 Cat: TD-2495 Single RCD (Safety Switch) Outlet Non-Contact AC Voltage Tester with Torch This non-contact tester detects voltages from 100 600VAC in mains outlets, power boards or insulated wiring etc. It also has an LED torch and a handy pocket clip. 180mm long. $ Pre-Programmed Smart TV Remote 17 95 Cat: QP-2271 RCDs (residual current devices) are designed to cut the power in a fraction of a second in the event of a fault condition. Use this handy portable one if your house doesn't have RCDs fitted. • Test function • Reset button • 10A 240V rated $ 24 95 Cat: MS-4013 300pc QC Crimp Connector Pack Finally, a Quick-Connector pack for regular everyday use. We have hand selected the contents of this pack $ 95 to ensure it contains Cat: PT-4536 300pcs of the most commonly-used quick connectors from our range of separately sold QC connectors. 29 12V Auto Work Light Ideal for use in caravans, boats, 4WDs and cars. This Auto work lamp draws a little over an amp and is supplied with 4.5m power cord with a cigarette lighter socket for easy connection. $ 14 95 Cat: ST-3032 Digital Tyre Pressure Gauge This simple device lets you keep track of tyre pressure and avoid pressure related problems. Includes an integrated torch for night use. • Range: 5 - 100PSI • 156mm long $ 19 95 Cat: QP-2293 Illuminated Gooseneck Magnifier I-Sight Magnifier with LED A handy little magnifying glass with a built-in LED light. Perfect for reading a menu in a dark restaurant, mapreading, hobbies etc. Battery and lanyard included. 65mm long $ This handy hobbyist's magnifyer has a 2 x main magnifier lens with a 5 x insert lens and 2 LED lights, all mounted on a flexible arm. Can be free-standing or clamped to a surface up to 38mm thick. • Lens 110mm (dia.) • Requires 3 x AAA batteries $ 9 95 29 95 Cat: QM-3532 Cat: ST-3197 Mini Bench Vice Shed/Garage/Boat Security Alarm The valuable tools and equipment stored in your garage or garden shed are an easy target for would be thieves. Protect them with this easily installed alarm. The self contained system includes a PIR, piezo siren, and reed switch. Simple plug & play installation. $ 95 • 120mm high Cat: LA-5400 Was $39.95 29 This strong lightweight aluminium vice will clamp to surfaces up to 1" thick and hold material up to 2" thick. Great for hobby work or for repairs on the go. $10 $ 14 95 Free Call: 1800 022 888 for orders! www.jaycar.com.au Cat: TH-1764 Contents Vol.21, No.8; August 2008 SILICON CHIP www.siliconchip.com.au Features 12 Printing In The Third Dimension Imagine an inkjet colour printer that outputs images not just in two dimensions (ie, width and depth) but adds the third dimension, height, as well to give 3D objects. The technology is here now – by Ross Tester Printing In The Third Dimension – Page 12. 18 Review: TekTronix DPO3034 Digital Oscilloscope The new 300MHz DPO3034 features a wide “digital phosphor” LCD screen, has an excellent user interface and boasts an impressive list of features – by Mauro Grassi Pro jects To Build 24 Ultra-LD Mk.2 200W Power Amplifier Module It uses On Semiconductor’s new ThermalTrak power transistors for superlative performance and delivers 200W into 4-ohms or 135W into 8-ohms with ultralow distortion. It’s also very easy to build – by Leo Simpson & John Clarke 32 Planet Jupiter Receiver Like to try some basic radio astronomy by listening to noise bursts originating from the planet Jupiter? This AM shortwave receiver lets you join in NASA’s world-wide Radio Jove project – by Jim Rowe 62 LED Strobe & Contactless Tachometer This LED strobe & tachometer project is ideal for measuring the speed of rotating machinery. It can do strobe measurements or you can trigger the tachometer using an optical pickup or photo-interruptor – by John Clarke Ultra-LD Mk.2 200W Power Amplifier Module – Page 24. 78 DSP Musicolour Light Show; Pt.3 Third article gives the final testing, troubleshooting and operating details and describes the firmware operation – by Mauro Grassi Special Columns 44 Serviceman’s Log She was just what I’d always fancied – by the TV Serviceman 57 Circuit Notebook (1) Charging Controller For 12V Lead-Acid Batteries; (2) Random Direction Control For A Model Railway Layout; (3) Antenna Resonance Indicator; (4) Balanced Supply Rails From A 12V Battery; (5) Universal IR Remote Control Repeater Planet Jupiter Receiver– Page 32. 88 Vintage Radio The incredible 1925 RCA 26 portable superhet – by Rodney Champness Departments   2   4 17 96 Publisher’s Letter Mailbag Order Form Product Showcase siliconchip.com.au 97 Ask Silicon Chip 100 Notes & Errata 101 Market Centre LED Strobe & Tachometer – Page 62. August 2008  1 SILICON 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, VK2ZLO Mauro Grassi, B.Sc.(Hons.) 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 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: $89.50 per year in Australia. For overseas rates, see the subscription page 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 Electrical wiring in older houses can be dangerous As might be expected, our recent articles on do-it-yourself wiring have generated quite a deal of comment, some of it very useful. For example, following our story on Light Switches in the July 2008 issue, a reader rang to point out that if anyone is changing a light bulb or doing anything else with a light fitting, they should be aware that the light socket can easily have power on it, even when the light switch is turned off. This is true and is particularly the case if the “loop” terminal has been used to terminate an Active wire. People should also be aware that some Edison sockets are inherently unsafe if they expose any of the metalwork which is connected to the lamp itself. This is because the outer screw thread of the lamp is part of the lamp circuit. In fact, in my opinion, 240VAC Edison lamps and fittings should never have been approved for use in Australia. So if you want to safely work on a light fitting or change an Edison screw light bulb, perhaps you should kill the power at the switchboard. So we do acknowledge that DIY wiring is not without its hazards. But provided people use common sense and the information available on the relevant New Zealand government websites, it can be done safely and correctly. However, Australian electrical supply authorities continue to the push the line that DIY wiring is “rooly rooly” dangerous. I am indebted to a reader who sent me a 4-page liftout inserted by Energex into the Brisbane Sunday Mail on June 8, 2008. In it they provide some perfectly innocuous information about using electricity safely, not using appliances with frayed power cords or overloading power points and so on. No problems there. But they go on to warn about the dangers of do-it-yourself wiring and state that “Hundreds of Queenslanders have been killed as a result of unauthorised or unsafe electrical work being carried out around the home”. Well, really? Over what period? Since Federation? This statement is patently untrue. Sure, hundreds of people may have been killed over a period of many years due to electrocution but the vast majority of those were nothing to do with wiring in the home, unauthorised or not. Our article in the June 2008 issue quoted from ABS figures and these show that there are typically three electrical fatalities in Queensland in a year. Only three? Yes. So why does Energex and other Australian electrical supply authorities continue to spend huge amounts of money advertising the evils of DIY wiring? We can only surmise that it is to stay on the good side of the electrical trades unions. Even then we cannot understand it, because most electricians would admit that they have more work than they can handle. In fact, it could be argued that if the electrical supply authorities really want to promote electrical safety, they should be highlighting the dangers of decrepit wiring in older homes, particularly those with cotton-covered or vulcanised rubber insulation. As fire departments and insurance companies can attest, this old wiring is a real fire hazard. In fact, if your home is 50 years old or more, the wiring is almost certain to be unsafe or in need of upgrading. Furthermore, if the supply authorities have so much money to spare, perhaps they should use it as subsidies for those people on lower incomes who cannot afford the cost of a full rewiring job. Leo Simpson siliconchip.com.au “I need an affordable power supply that won’t risk my DUTs.” Done. And we added memory, too. Introducing the Agilent U8000 Series single-output, non-programmable power supply. It comes packed with more features than you’d normally expect in an affordable power supply. Fully integrated overvoltage and overcurrent protection keep your DUTs safe while you work. A keypad lock and physical lock provide added security. And, the capability to save and recall up to three memory states shortens set-up time and reduces mistakes. What’s more, it’s an evolution of the best-selling Agilent E3600 Series and backed by 40 years of experience in power supplies, so you know it • Power Range - 90 W to 150 W has reliability you can count on. • Voltage/Current Range - up to 30 V/5 A For more on the U8000 Series, www.agilent.com/find/lowcostpower Call Agilent 1800 629 485 Agilent Authorised Distributors www.measurement.net.au Western Australia, Northern Territory (08) 9437 2550 www.rftest.co.nz New Zealand (64) 4 570 2480 www.triosmartcal.com.au Australia ACT, NSW, QLD, SA, TAS, VIC (1) 300 853 407 © Agilent Technologies, Inc. 2008 siliconchip.com.au August 2008  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”. Brushless DC is the correct motor description The article on the Vectrix motorcycle has a point in asking whether the motor should properly be called a “brushless DC motor”. In fact, the motor proper is either an AC synchronous motor or an induction motor. Either type can be fed from an inverter, in principle. But then nearly all DC motors have an armature which is that of a synchronous motor. The commutator and brush gear ensure the armature is always “in sync”, including at zero speed. The only true DC motor is rarely seen and is called the homopolar or acyclic configuration. The rotor is the armature and is just a very large flat copper disc with a brush at the axis and another at the rim. The field is a horseshoe magnet mounted so that the magnetic field is normal to the radial line between the two brushes. Wrong capacitor in frequency indicator I built the “Frequency Indicator For Generating Equipment” from Circuit Notebook (SC May 2008). I had trouble getting the oscillator going at 500Hz. I think the 150nF capacitor should have been 15nF. However, even using this value I couldn’t get the required range of frequencies. Instead, I ended up using a 1.2MW resistor in series with the 100kW trimpot and a 10nF (0.01mF) capacitor. I also think that The acyclic motor is thus very simple; the drawback is that the armature current required is enormous, up to one million amps, depending on the application. Therefore, “brushless DC motor” is arguably an appropriate term as the inverter does exactly the same job as the commutator and brush gear. I prefer to separate the two functions into “inverter” and “AC motor”, the latter being either synchronous or asynchronous (induction). My reason is the combination is much more capable, albeit more expensive, than the conventional DC motor. John Waller, Plainfield, Connecticut, 06374-1429, USA. Don’t change settings while power is applied I read the article on the Low Voltage Adjustable Regulator (SILICON CHIP, May 2008) with some interest because the design is nearly the same as one I calibration can be made by plugging the plugpack into the 240VAC mains which is really close to the 50Hz required for calibration. This will avoid the need for accurate frequency meter. Jim Graham, Moonah, Tas. Comment: it does appear as though the 150nF capacitor is out by a factor of 10, as you suggest. Using 50Hz mains to calibrate the unit is an obvious approach – why didn’t we think of that? built for myself nearly a decade ago. In my design, I used a 6-position wafer switch to change the value of the resistor between the regulator’s adjust terminal and ground. However, the switch was a break-before-make type and that led to the demise of a perfectly good Walkman cassette player. I realised after I’d plugged the Walk­man into the regulator that I had set the voltage selector switch to 3V instead of 6V. Without thinking of the consequences, I changed the voltage output setting with the switch, without disconnecting the Walkman. For the brief period while the adjust terminal is disconnected from ground via a resistor, the output of the regulator rises to almost the input voltage, in my case 24V. Ouch! The result was one dead Walkman. I think it would be a good idea to issue a warning in the next edition of SILICON CHIP that removing the jumper shunt with a load connected is asking for trouble. Otherwise it’s a great project that will be very useful for many of your readers. Peter van Schaik, Tenterfield, NSW. Website for info on connectors and pinouts Your readers may be interested to review the AllPinouts’ website at http://www.allpinouts.org AllPinouts, a community-built reference archive for connectors and cable pinouts, is currently the world’s largest pinouts archive, listing more than 1400 technical pages. This is a www.furzy.com We Create Electronic Controllers 4  Silicon Chip siliconchip.com.au EVs & solar power are viable together I feel the need to put pen to paper and wade into the argument for EVs, especially relating to Dave Waplington’s letter in the February 2008 issue. Dave has a system that recharges his EV from a solar array and he tells us that after a few hours his batteries are full and he is ready to do his day’s driving. Presumably, the vehicle in question has adequate range for his day-to-day driving needs and he, like most of us, has another car that runs on some sort of liquid fuel for any longer trips. Peter Seligman replied that the solar array produces X amount of power on average and electricity costs Y amount so that the array will take Z (where Z is a big number) years to pay off but that’s not correct is it? In fact, Dave’s solar array displaces petrol and if he would have used, say, $50 per week, then his array will only take around 6.5 years to pay off. But Dave no longer has to pay for maintenance for the engine or drive-train that he doesn’t have – things like filters, cam belts, radiator coolant, etc. Most especially, he will free content project that collects information about hardware interfaces of modern and obsolete hardware, including pinouts of ports, expansion slots, and other connectors of computers and different electronic devices such has cellular phones, GPS, PDA and game consoles. Created with the same MediaWiki software that was developed for the Wikipedia project, AllPinouts allows registered users to contribute and improve the website. All text is available under the GNU Free Documentation License (GFDL) and may be distributed or linked accordingly. Nicola Asuni, Cagliari, Italy. When an electrical engineer cannot do electrical work I have a Degree in Electrical Engineering which I received as a cadet with Pacific Power, formerly known as The Electricity Commission of NSW. siliconchip.com.au not have to pour five litres of highly refined oil into his engine every six months. So let’s plug in some hypothetical numbers: Dave sells his electricity to the grid during the day when it’s 10c per kilowatt-hour. Let say he makes 10kWh so he gets 100c credit. During the night, he charges his car from off-peak electricity that he purchases for 5c/kWh and it costs him around 40c (since it only takes around 8kWh to charge the car). That means he ends up with 60c worth of credit to offset against his daily consumption; not a fortune to be sure, but still pleasing to behold. As far as I’m concerned, that really puts things into the realm of the financially possible – especially if an EV was competitive in price to that new car that you now covet. It helps out the country’s energy situation too. The system produces power when it’s really needed and perhaps keeps the power companies from having to fire up their huge turbines to meet the demand peaks during the day. And then it puts some load onto the spinning reserve at night. Nice one Dave! Ned Stojadinovic, Gunning, NSW. I majored in Telecommunications but my electives were all Power Engineering-related. I also have a Certificate III in Telecommunications Cabling and an Advanced Amateur Radio License. Within the Ham Radio world, I am the only non-North American board member of TAPR, who pioneered Packet Radio Technologies. In my professional life I was employed by Pacific Power/Electricity Commission of NSW for 13 years, from 1990 until 2002. My first five and a half years with them were as an undergraduate attending UTS and working at various sites. While at University, my first Industrial Semester of about nine months was at the Homebush Apprentice Training School, where I learned electrical trades with first year apprentices. I then spent some time working in an office situation with Controls and Instrumentation, with regular power station trips. This was followed by a Atmel’s AVR, from JED in Australia JED has designed a range of single board computers and modules as a way of using the AVR without SMT board design The AVR570 module (above) is a way of using an ATmega128 CPU on a user base board without having to lay out the intricate, surface-mounted surrounds of the CPU, and then having to manufacture your board on an SMT robot line. Instead you simply layout a square for four 0.1” spaced socket strips and plug in our pre-tested module. The module has the crystal, resetter, AVR-ISP programming header (and an optional JTAG ICE pad), as well as programming signal switching. For a little extra, we load a DS1305 RTC, crystal and Li battery underneath, which uses SPI and port G. See JED’s www site for a datasheet. AVR573 Single Board Computer This board uses the AVR570 module and adds 20 An./Dig. inputs, 12 FET outputs, LCD/ Kbd, 2xRS232, 1xRS485, 1-Wire, power reg. etc. See www.jedmicro.com.au/avr.htm $330 PC-PROM Programmer This programmer plugs into a PC printer port and reads, writes and edits any 28 or 32-pin PROM. Comes with plug-pack, cable and software. Also available is a multi-PROM UV eraser with timer, and a 32/32 PLCC converter. JED Microprocessors Pty Ltd 173 Boronia Rd, Boronia, Victoria, 3155 Ph. 03 9762 3588, Fax 03 9762 5499 www.jedmicro.com.au August 2008  5 More on the Enersonic Power Saver With reference to your article on the Enersonic “Power Saver” in the May 2008 issue, I acknowledge that this device is a fraud. However, I feel when it came to the power factor correction, Leo expressed surprise when he plugged the Power Saver in with a fridge and got a greater power reading. As electronic gurus I assume we know about Apparent, Reactive and Real powers right? What Leo forgot is that the Apparent power of his fridge remained essentially the same with or without the “Power Saver”; what changed was the power factor. A quick calculation proved that by changing the power factor, the power increased from 220W to 240W, and the Reactive Power decreased from 3-month placement with the Environmental Section at Wallerawang Power Station. Following graduation, I was appointed to Bayswater Power Station’s Electrical Branch where I was a plant owner for DC Systems, Switchboards and Motors. I obtained my High Voltage certification, and performed 240V/415V work at various times without supervision. AS3000 exempted supply authorities, meaning that I was permitted to operate in this 6  Silicon Chip 101VAr to 31VAr. Leo thus neglected to mention that “because of this”, it uses more power, as our homes are measured in Watts. It could only work if Apparent power is measured and power factors are an issue (as pointed out in the article). “You haven’t told us anything new!” Yes, I have. In the article it was stated several times that it uses power in its internal circuitry and that negates any savings the power factor correction does. What I’m telling you now is, that by correcting the power factor, it’ll make the home meter tick over more power, so it doesn’t save anything there either, ie, the fridge, with 220W compared to the 240W, you will be paying for 20W more with the “Power Saver”. Matthew Thompson, Gawler, SA. manner. I was one of two engineers in the branch and my boss held an Electrician’s License as well as being an Electrical Engineer. After spending about nine months at Bayswater, the organisation was split up and I spent my remaining time assisting with the management of Engineering Information such as drawings. When I left, my employer paid for me to complete my Certificate III in Telecommunications Cabling as part of a redundancy. With all this experience you would think that it would be easy for me to obtain an Electrical License. It is actually basically impossible for me. You see, I need to have two years of electrical wiring experience in order to get my license. This is a special requirement because I have an Electrical Engineering Degree. Any other type of Engineering Degree would make me ineligible. But the experience must all be post-graduation so the structured experience I have from the Apprentice Training School does not apply. If I did manage to get the experience I would still need to do a TAFE course to prove that I have the expertise. In my professional life, I have needed to install alligator clips onto the end of a 3-phase 415V lead in order to test the protection on an 11kV motor at a safe voltage. I have worked on a 240VDC 800A Battery Charger live in order to repair a faulty card. The organisation I was working for trusted me to do these things in order for me to do my job. But I have also seen a tradesman injured when he came in contact with live wires on a switchboard when a cover was not replaced. And I have seen electrical apprentices make extension cords with plugs on both ends. I am qualified and competent to design the electrical system for a house or factory. I can legally install any of the communications infrastructures. I siliconchip.com.au Banning live mains work will save lives In your Publisher’s Letter in the June 2008 issue of SILICON CHIP you have hit the nail right on the head – electrical safety legislation in Australia is a joke. The New Zealanders have it right and they have the statistics to prove it. Banning live mains work? That’s a joke! What about intermittent mains power problems that can’t be fixed other than by live work? Most people in this industry understand such problems from personal experience. I am not suggesting that workplace safety programs are a waste of time. Quite the opposite – so long as they get results and reduce injuries and deaths, I’m all for it. “Nanny state”? You’re so right again. There are so many examples, can design a control system down to board level. But I am not permitted in this country to install any of it. I do not begrudge the need to ensure that people are competent but there must be some middle ground. At the moment there is no middle ground. Darryl Smith, VK2TDS Ingleburn, NSW. Comment: your situation is identical to that of many highly-qualified electrical and electronics engineers throughout it would take forever. Most obvious is the near exponential increase in the number of regulations that an ordinary citizen must now comply with. You need to be a bush lawyer just to get a driver’s licence or build a dunny these days. Oh, sorry, you can’t install a toilet without being a licensed plumber. I believe that excessive regulation is a blight and is ultimately self-defeating. Even law-abiding citizens ignore lots of petty rules in a desperate attempt to simplify their already overloaded lives. Colin Beeforth, Doveton, Vic. Comment: we think there is considerable merit to banning live mains work. After all, if the majority of electrocutions occur among electricians and electrical contractors, such a ban is in their interest. FRONT PANELS & ENCLOSURES Customized front panels can be easily designed with our free software Front Panel Designer • Cost-effective prototypes and production runs • Wide range of materials or customization of provided material • Automatic price calculation • Fabrication in 1, 3 or 7 days Sample price: USD 43.78 plus S&H Australia. This is just another example of how over-regulation produces ridiculous results. Another engineer’s viewpoint on electrical wiring www.frontpanelexpress.com When SILICON CHIP last raised the issue of DIY electrical work I was fully in support of what you were trying to achieve. I believed that I should have the “right” to do electrical work since I have a degree in electrical engineering, I grew up in a family business which involved some types of electrical work and I held other jobs and interests which were related to electrical work. Several years ago I began an electri- Australia’s Lowest Priced DSO! Now you’ve got no excuse ... update your old analogue scopes! Whether you’re a hobbyist, TAFE college or university workshop, the GW GDS-1022 has the price and performance for you. GW GDS-1022 25MHz 25MHz Bandwidth, 2 Ch 250MS/s Real Time Sampling 4k Memory Per Channel TFT Colour Display 19 Auto Measurements Built-in USB & SD Card Slot GW Brand - 28 years in Australia Sydney Melbourne Tel 02 9519 3933 Tel 03 9889 0427 Fax 02 9550 1378 Fax 03 9889 0715 email testinst<at>emona.com.au siliconchip.com.au Brisbane Tel 07 3275 2183 Fax 07 3275 2196 Adelaide Tel 08 8363 5733 Fax 08 83635799 Perth ONLY $ Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au 499 inc GST SAVE $ 50 EMONA August 2008  7 Mailbag: continued Helping to put you in Control PLC’s We have a selection of programmable logic controllers and HMI displays XC3 High Performance PLC features a large number of functions, large memory, small size and fast scan times. Functions include PWM and 2 axis Stepper and Servo Motor control. Prices from $215+GST. Programming available starts at $99+GST XC5 High Performance PLC A more powerful and larger I/O version of the XC3. Includes PWM and 4 axis Stepper and Servo Motor controls Prices from… $525+GST XMP3 PLC and HMI The XMP3 is a PLC and HMI display all wrapped up in 1 unit. Can do 2 axis stepper and servo motor control $425+GST OP320A Operator Panel 4 x 24 Character LCD, 20 Programmable keys supports popular PLC protocols. Can be connected to our XC3 and XC5 PLCs $249.00+GST TP562-T Touch Screen Display 5.6 inch 256 color TFT 320*240 pixels 4MB FlashROM 4KB SRAM. Support for various popular PLC's $799+GST TPA61-T Touch Screen Display 10.4in, 256 color TFT 800 x 600 pixels 8MB FlashROM 4KB SRAM. Support for various popular PLC's $1699+GST Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au 8  Silicon Chip cal apprenticeship and I realised that what the electrical industry claims is in fact true – there’s a lot more to electrical work than just the perceived ability to connect a few wires. A home’s wiring is an intelligently planned and carefully built system which is designed to reduce or eliminate many dangers with using electricity. Any one defect can bring that whole system down. I learnt that despite my previous skills and qualifications even my own knowledge was limited. No amount of study or other experience can compensate for real experience while working under a fully licensed electrician. The wiring rules, AS3000, are over 450 pages and it takes years to learn it thoroughly. You’d be amazed at how many rules are applicable for something even as “simple” as renewing a power point – rules and techniques which you’d never know unless you do an apprenticeship. Personally, I don’t care if I come across unlicensed work as long as it complies with the rules. But I can easily identify it if it is done wrongly and I have to fix it. Make no mistake that a false sense of confidence in electrical work will lead to more dodgy work. Now with respect to the June 2008 article, so you remove your switch or power point and one of the wires breaks off. How do you fix it? What’s the difference in technique between solid or stranded cable? Are all the wires the same size? What if the insulation is degraded? What if there is no earth? Or bare earth? Or a flexible cable connected? Or a red and black wire connected together? You can’t just shove it back in the wall and pretend it’s not there – it must be made compliant or disconnected. Only an electrician has the knowledge to rectify ANY problem arising. How many handymen do you think will pay $100 for AS3000? Then how many would learn and understand it thoroughly? Yet this is the bible for electricians, a code to which all work must comply. Except for a few people such as yourselves at SILICON CHIP, most won’t even want to know about these wiring rules because “it’s only a few power points anyway.” A good test for all who demand the right to do electrical work is to take a sample Licensed Electrical Theory (LET) exam: http://www.electroskills. com.au/downloads/LET Sample Exam.pdf The pass mark is 75% and the time limit is two hours. The two practical exams are similar and are the culmination of four years of training. Are you handymen capable of passing these? I surmise another reason for this debate is that electricians are perceived by some to be of low skill and education. Well, I can tell you that the schooling and final exams were no walk in the park. Combined with the practical aptitude required, it makes electrical work into a skilled profession and that’s the reason why government authorities treat it as such. Robert Hatvani, B.E (Electrical) RMIT; Cert. III in Electrotechnology (Systems Electrician) Box Hill TAFE. Digital LC Meter calibration procedure With regard to the Digital LC Meter described in the May 2008 issue, maybe there’s something omitted from the explanation of how the “calibration mode” works but it seems to me that equation (3) calculates C1 from C2. The problem is that it doesn’t know the value of C2. If it assumes C2 is precisely 1nF but is off by 1% it cannot “measure” the value of C1 to any better than 1%. This is a bit useless if we already know the value of C1 to within 1%. Can you please explain how “calibration mode” really works? Mike Hudson, Chester Hill, NSW. Comment: you are correct in deducing that the calibration of the LC Meter is essentially based on the accuracy of C2. However, if this is only known within 1%, the calibration modes allow the instrument itself to be ‘fine calibrated’ against an external capacitor if you have one whose value is known more accurately than 1%. The important thing to remember is that once the meter is calibrated, its accuracy is the same for inductance siliconchip.com.au Comment on electric cars I have been an enthusiastic reader of SILICON CHIP since 1999. Its wellbalanced content has always been able to retain my full attention over all these years. In contrast to a recent reader’s letter, I am always waiting for the next publication of a PICAXE-related article. Since the advent of the PICAXE VSM simulator (SILICON CHIP, January & February 2008), it all became even more exciting. I also would like to congratulate you on your regular “Publisher’s Letter” and the very personal stand you take on socio-economic issues that will influence all our futures. You recent articles on electric cars and the Vectrix were very interesting. I think, it is important to push ahead in this field regardless of the present shortfalls of the current technologies and products available. They all are essential “path cutters” to better solutions in the future. What would have become of aviation if people had given up at the stage of the Tiger Moth? Now back to the electric car: Your article in the April 2008 issue stimulated me to build a simple spreadsheet model regarding the economy and the availability of alternative power sources. What it shows is that even if we could convert all cars to electric over a short period of time, there would not be enough power available. We would have to roughly triple the output of our power stations! as well as capacitance. And even 1% accuracy is adequate for measuring inductors. Home Electrical Safety License should be available Your article on DIY wiring in the June 2008 issue was a good read and challenged the convention in Australia. It would seem that entrenched thinking and powerful lobbies keep us from being credited with a small amount of intelligence and ability to learn. I do have a suggestion. Might it be possible to introduce a “Home Electrisiliconchip.com.au A couple of years ago, I was involved in projects with fuel cells and hydrogen for temporary storage of electric energy in remote areas. Although there are merits for these special applications, I think fuel cells will not be a satisfactory and available solution for individual transport, for the simple reason that the generation (or availability) of hydrogen is too inefficient and expensive. In a little fuel-cell model system we used an electrolyser to generate hydrogen from electric energy (solar panel or mains supply). The hydrogen was then stored in metal hydride cylinders and released to the fuel cell on demand, which converted it back into electric power driving some load. The loss of energy (very rough estimate) from electric to hydrogen was 50% and from hydrogen back to electric another 50%. This means that from 100W injected into the system, only 25% was retrieved. Any battery or super-capacitor can do much better. Bio-fuel, already in competition with the production of food, seems to be no alternative either. What remains suggests being a drastic cut in overall energy consumption, which would mean using public transport for the majority of our needs, supported by small low-energy vehicles to get from home to the next bus or train stop. Cars as status symbols have become a joke. Klaus D. Fahrner Munster, WA. cal Safety License” that would allow Australians to work on their homes in a similar manner to New Zealanders after a suitable training course? This concept of a suitable short training course aimed at specific required knowledge is not new and is already embodied in such areas as the “Skippers Ticket” here in WA, obtaining the Marine Radio Operators Certificate of Proficiency or even the Foundation Amateur Radio License. It seems to me that the essentials of electrical safety around the home could be covered in a short course followed by a practical and theory ew See revi’08 e n u in J HIP SILICON C ALTITUDE 3500-SS Valve Stereo HiFi Amplifier 32W/Channel, 4 or 8Ω “This particular valve amplifier performs very well” Leo Simpson SILICON CHIP June 2008 A blend of quality components and modern design Beautifully finished in 7mm brushed aluminium Four stereo analog inputs Gold plated connectors and selectors Extended bandwidth of 10Hz to 90kHz Carefully chosen design layout and wiring location Direct input coupling improves transient response Specialised wide-bandwidth audio output transformers Class A/B pentode output using genuine Russian-made Electro-Harmonix EL34 valves Matched pairs, factory bias adjusted Stainless steel heat shields improve overall efficiency High quality capacitors Beautiful in looks, design and listening The A3500-SS is an exclusive and advanced version developed by Stones Sound Studio. Retail price is just $1899, available now from ELECTRONIC SERVICES AUSTRALIA 138 Liverpool Rd, Ashfield NSW (Locked Bag 30, Ashfield NSW 2131) Ph: (02) 9798 9233 Fax: (02) 9798 0017 Web: www.wagner.net.au August 2008  9 Save Up To 60% On Electronic Components Great New ET-AVR Stamp Only $23.88 * Includes ATMega128 Microcontroller * Up to 53 I/O Points * 8-Channel 10-bit A/D * Direct In-Circuit Programming * Ideal as a Removable Controller Exciting New ET-ARM Stamp * Includes LPC2119 Microcontroller * High-Speed Operation * Heaps of I/O plus CAN, UART, I2C * In-Circuit Programming * Supporting Board Also Available Only $33.48 New Solar Regulator Compact, inexpensive, easy-to-use solar regulator in 5A, 10A and 30A sizes. Only $31.08 We are your one-stop shop for Microcontroller Boards, PCB Manufacture and Electronic Components. www.futurlec.com.au examination to establish the candidate has understood the course content. A license could then be issued to the successful candidate to work on his own home. It seems simple and there would be organisations out there willing to run such courses if it meant they could charge and make money from it. The electrical lobby groups could even do it and perhaps through the course might encourage people to take up an electrical apprenticeship or am I dreaming? Nigel Dudley, Oakford, WA. Comment: that’s a great idea. Old inverters need not cause interference In response to Bruce Bowman’s letter in the May 2008 issue, I am surprised about the interference he experienced 10  Silicon Chip Mailbag: continued Old TV sets need good homes Having had a keen interest in TV over the years, I have a number of old non-working colour TVs (late 1970s to mid 1980s) that I am going to trash if I am unable to give them away. I am willing to deliver them in the Brisbane, Logan & Redlands areas if required. I should have schematic diagrams for most of them. The list of sets is: Brand Name Model/Chassis Circuit Available Commander CHT 9102 Yes Goldstar CB2 6105 Yes JVC 7465 AU Yes Kriesler 59-1 Yes Kriesler 37-104 Yes Philips KT2A Yes Pye Series85 48 LRIN-T No Rank Arena C 2252 No Sharp C 206X No Sony KV-A29115 No Thorn 9014 Yes Please contact me via email at llwinter<at>bigpond. com.au, with “Old TV’s” in the subject line. I really do not wish to see them go to the tip. Lawrie Winter, Logan, Qld. from the Ferris vibrator inverter described in the February 2008 issue. I have several of these in my collection and as I run a small 12V wind and solar-powered lighting plant, one of them often runs all day, powering a 1948 Breville mains/battery portable valve radio. I live 80km west of the Sydney AM stations and receive them without any problems, and that’s with the internal loop aerial alone. However, I should point out that there was some interference until I earthed the negative of the 12V supply. I wonder if lack of earthing was the cause of Mr Bowman’s problem. I am also surprised at the claim that these inverters were not meant for powering radios. Not only does the label on the front panel indicate their suitability for this but this model of inverter was specifically meant as a companion to the Ferris 106 mains/battery portable, for in-car operation. siliconchip.com.au Incidentally, running the radio off a 100Hz square wave will be more efficient as far as power supply filtering goes. Not only will the filter choke and capacitors be more effective but the square wave means there’s a lot less “dead” time in the supply waveform that the filter has to compensate for. Any interference problems are therefore likely to be RF-related. Just to clear up any possible misconceptions that vibrator power supplies are inefficient, I fail to see how this is so when there is virtually no voltage drop across the contacts when closed (as opposed to the saturation voltage of a bipolar power transistor). Apart from transformer losses, the only power required to run such an inverter is the 200-odd milliamps to drive the vibrator reed. The fact that a 100W transistor inverter needs heatsinking and the vibrator equivalent doesn’t says something. The other advantage is that the vibrator inverter isn’t damaged by momentary overloads and happily works irrespective of input polarity. Modern inverters with their H-bridge of power Mosfets switching 340VDC are rather fragile by comparison. It only takes microseconds to end up with an array of blown (an expensive) Mosfets. I have quite a collection of homemade and commercially made vibrator inverters, as well as vibrator-powered valve radios. From current measurements, it seems that efficiency is very good; 80% is not impossible to obtain. I’ve built a few inverters with toroidal transformers and these work even better, with greater efficiency and less RFI suppression required. Neither has reliability been an issue with the MSP (AWA) or other vibrators with series-driven reeds. The Ferrocart (Astor) units, on the other hand, sometimes need some TLC but there is an MSP plug-in replacement (type V0410) which completely eliminates that problem. Having said that, I have come across some bad examples of vibrator power supplies with poorly chosen buffer capacitors or poor transformer design. To horrify people even more, apart from running valve radios and vibrator inverters off my solar/wind supply, there’s also a multitude of incandescent light bulbs! Finally, in response to the claim by Rodney Champness in his Vintage Radio column in the May 2008 issue, that there were no 12V or 32V TV receivers made locally, there were, in fact, some Ferris models, such as the C21F. These had an external power supply in a stand-alone box and allowed for mains or battery operation. The valve heaters were wired in series/parallel for 12V or 32V. The mains supply was conventional except for the 12V or 32V heater winding and the battery supply had two separate vibrator supplies in the one box with their DC outputs paralleled. A later set, the 32V model B23, used a transistor supply to provide the high tension. There was also the AEI-Ekco TX276 9-inch portable with 12/240V operation. The 12V supply was internal and simply consisted of an extra power transformer winding and vibrator which were brought into operation for 12V DC operation. John Hunter, SC Hazelbrook, NSW. siliconchip.com.au Small Colour TFT LCDs Door Camera 5.6‛‛ Small TFT LCD √ √ √ √ √ 4.0‛‛ Small TFT LCD Full Color TFT LCD NTSC&PAL Compatible With Picture Quality Control DV 12V Operation Simple Wire Harness Connection Digital Video Recorder Modules DVR8100 Video & Still Image Recording On Motion Detect √ √ √ √ √ √ √ 2 Video Ch Input NTSC&PAL Alarm output Trigger input SD card On Board Flash JPG&AVI file format √ √ √ √ √ √ √ Real time clock Date & time stamp PIP, OSD With keyboard RCA connections DC input (9V to 12V) Kit available DVR623 DSC/DV Module √ Mega pixel image sensor √ Real time Video output √ Storage to SD card √ OSD DV: √ VGA or QVGA √ Frame rate 1, 10, 30fps √ Recording from 1-99 sec √ Preset capture schedule √ Trigger input DSC: √ 3M, 1.3M & VGA √ Picture-in-picture √ Preset capture schedule √ External trigger input √ Keyboard snap shot TM www.tenrod.com.au sales<at>tenrod.com.au NSW: tel: (02) 9748 0655 fax: (02) 9748 0258 VIC: tel: (03) 9886 7800 fax: (03) 9886 7799 QLD: tel: (07) 3879 2133 fax: (07) 3879 2188 NZ : tel: (09) 298 4346 fax: (09) 353 1317 Unit 1, 24 Vore Street Silverwater NSW 2128 August 2008  11 By Ross Tester Printing in the Third Dimension Imagine a colour printer that outputs images not just in the two dimensions we’re all familiar with – width and depth – but adds the third dimension, height, so that the “printed” images can be physically held, picked up, turned, inverted . . . just like any other 3D object. 12  Silicon Chip siliconchip.com.au A few months ago, a company called SOS Components placed a flyer in SILICON CHIP advertising their rapid prototyping bureau. It looked fascinating but, not being involved with anyone who needed or used such a service, I’d all but forgotten about it . . . until I came across the company’s stand at this year’s national manufacturing week exhibition. Centrepiece of the stand was a magnificent model boat. It would have been well over a metre long, 250mm wide and perhaps 350mm deep. I was informed that this boat was an exact scale model of a boat currently being built in Queensland for a (very!) well-heeled individual. Now prototypes or models are not exactly new – a lot of models, for all sorts of “products” are built before production begins. The client might want to make structural or cosmetic changes once they see how the “thing” actually looks. And it’s normally a lot cheaper to do it earlier than later. A lot of companies also make accurate models of proposed new products for evaluation, testing, checking and so on. But this was no ordinary model boat. It wasn’t carved from a block of balsa or modelling plastic by a skilled modelmaker, labouring away for perhaps several weeks. In fact, it wasn’t carved at all. It was printed, in the true sense of the word, layer after layer after layer – and in colour! Due to size limitations of the printer, (maximum build size is 250 x 350 x 200mm), it was “printed” in four sections which were then glued together. Because each section was extremely accurate, there were virtually no join edges – just some very minor retouching was all that was needed to hide the seams. That’s a photo of it at left, with the man who “printed” it, Jeff Condren, from SOS Components in Brisbane. To say it was impressive is at best an understatement. However, it wasn’t all that SOS were displaying. Across the back of the stand was a large (>2m x 2m) model of a proposed Brisbane motorway intersection. Note the word You better believe it: it’s a model of a Tupperware bowl, complete with removable lid moulded in “Superflex” – developed in Australia by SOS Components. “model”. It wasn’t just your usual flat “map” with a few cars and trucks added to make it look more realistic; this one had all the terrain in accurate scale, the cuts for the motorway lanes where required, the hills and landscaping alongside – it was just like looking down on the scene from a few hundred metres up. Then there were quite a number of “model” buildings, engineering samples, appliances, components, even soft plastic bottles (more on this innovation shortly) – all in accurate scale, most in colour. Because the layers are printed, any “internal” parts are formed exactly as they would be in the real thing – even movable parts. For designers and engineers creating a new product, this aspect is so valuable. They can actually see how the components fit into one another, how they react, if the clearances are correct and so on. But it takes a little bit to get your head around the fact that every one of these is printed, not carved, cast, stamped or any other, shall we say “conventional” method of producing models or miniatures. A sense of déjà vu? Regular SILICON CHIP readers may recall a story we published back in the September 1996 issue on a process Take a set of architect’s drawings, convert them to 3D . . . and print them! Just imagine how much more likely the sale would be when a potential buyer can see a real model of what they are being offered! siliconchip.com.au August 2008  13 for producing prototypes. At first glance, it might appear that the processes are the same. While they are, to some degree, similar, that’s like saying Minis and Maseratis are similar. Things have changed significantly in the last decade or so. For a start, the process we looked at in 1996 used a laser beam to “sinter” a layer of fine powder together. (Sintering is the amalgamation of material by heat, without melting). The article also discussed a process where a layer of adhesivebacked paper was laser-cut and stuck to a previous layer, building up one layer at a time. The process we are looking at here is true printing – in fact, four-colour (CMYK – cyan, magenta, yellow and black) printing, as used in this magazine. There aren’t many colours that CMYK printing can’t replicate reasonably well – fluoro colours and bright orange/bright green are the main exceptions. However, by combining various percentages of inks, the vast gamut of colours can be produced very successfully and is one of the reasons the CMYK process is used so extensively. However, unlike the offset (roller) printing used for most CMYK jobs, the 3D printer works in much the same way as an inkjet printer. First it deposits a very fine layer of tiny beads of powder, then sprays microscopic droplets of ink onto the powder in the required pattern as the head passes over. As the powder is “wet” by the ink, it effectively turns it into a glue which bonds to the layer immediately underneath. As the ink dries, the powder/glue hardens. Then the process is repeated – over and over – and every time the printer head makes a pass over a layer and it is completed, the whole thing drops down about 0.1mm, ready for the next layer. Thus the image is built up, layer by layer, until the 3D image is produced. Only the areas of powder hit by ink droplets are affected, so all of the other powder remains in its original condition and is available for re-use – in fact, it is collected for that very purpose. If the original had printing, colouring, texture mapping or labelling, so will the 3D-printed “image” Complexity is no problem – it takes exactly the same time to print a highly detailed, intricate image such as those shown on these pages as it does to print a brick the same size! Where does it get the image to print? Like any “conventional” printer, the 3D printer requires “driving instructions” to tell it where to deposit which ink The medical applications, particularly in a learning environment, are enormous: above is a human heart, printed from an MRI Scan. This heart, though, comes apart as seen top right so that all the chambers and valves can be seen exactly as they should appear. For good measure, lower right is a “slice” or cross-section of a human kidney, complete with colour-coding to show how it works. 14  Silicon Chip siliconchip.com.au and in which quantities to reproduce the colours required in the places required. Most printers simply need X and Y co-ordinates but the 3D printer also needs Z – the depth. The image might come from a 3D laser scan, an architect’s or engineer’s drawing in a CAD program or even, as we saw earlier, scaled down plans of a ship, a building, a spacecraft . . . in fact, just about anything that can be plotted in all three dimensions can be used to print the solid object. Where did the process come from? The 3D printing process was invented by Dr Jim Bredt and Tim Anderson, students at the Massachusets Institute of Technology during the early 1990s. Part of Dr Bredt’s PhD thesis involved the use of low-cost printer technology to produce 3D images. They formed ZCorporation which, with a licence from MIT for the 3D printing process, has now grown to an organisation with distribution and service in 61 countries and over 160 employees. SOS Components are the Australian distributors of ZCorporation products. The can produce elastometric parts, direct casting moulds, investment cast patterns and snap-fit parts directly off the printer with no machining required. These take hours instead of the traditional prototype days – and in fact are generally much more accurate than a hand-made (machined) prototype. Superflex However, SOS has taken the ZCoporation idea another step further with Superflex. By using a compound they developed themselves, SOS can produce flexible parts in a 24-bit colour process. Complexity is no problem, as this highly-detailed model of a machine demonstrates. This would have taken exactly the same time to print as a brick of the same size! (Right): Complete with obligatory “Save $XXXX” show stickers, one of the ZCorporation 3D printers – in this case the Spectrum Z510 – on display at the Manufacturing Week exhibition. Below is a close-up of the business end of the printer. On the extreme right is the movable print head which sprays microscopic ink droplets onto the powder in the well at left. As each pass is made, the bin containing the powder drops down a miniscule amount and a fresh layer of powder is laid down, ready for the next ink spray. The size limitation of this particular printer can be seen; hence the need for the model boat at left to be printed in four sections and then glued together. Because the printing process is so precise, the complete model appears virtually seamless. siliconchip.com.au August 2008  15 Want to know how a turbine works? The students can see “inside” the turbine with this exploded view of a turbine. Printed with all components already in place (and again colour-coded to aid understanding) this model would take hours to produce instead of weeks in a model-making shop. A “plastic” bottle printed with Superflex. As you can see, it behaves just like a “real” plastic bottle would behave. This enables the customer (and therefore evaluation and market research groups) to not only touch and feel a prototype product, they can squeeze it and flex it – just like the real thing would behave. Prototype squeeze bottles or extrusions that can be squeezed or flexed make a world of difference when it comes to product evaluation. Because they are printed and the (non-hardened) inside sections removed, empty bottles can be just that. If the design has movable internal parts , the model will have movable internal parts. And parts in the design that move with respect to other parts can move with respect to other parts in the model – and be checked that they do move! Who uses this service? Just about anyone who needs a highly accurate model of just about anything – for just about any purpose! The obvious users are in product design and development, advertising agencies, architects, real estate developers, colleges and universities . . . and then there are the not-so-obvious such as demonstrated by the model boat photograph. 16  Silicon Chip As a sales aid, it is without peer. You can just imagine how much more impressive is a scale model of a multimillion dollar bridge or freeway than even the best aerial photos. It’s more than likely that the 3D printing process has used those same aerial photographs, added data from topographic maps and voila! – a 3D “map” where everyone can see heights and relativities. Similarly, product prototypes: Proctor and Gamble’s Tim Smith said “We’ve handed people pictures, we’ve even handed them 3D glasses to watch a screen. But I never saw jaws hit the floor until I handed them a part in full colour!” Motorola’s V70 phone was extensively designed using the ZCorp 3D printing process. Many different models were made to be market-tested as well as in-house evaluation, with the final design achieving the design goals simply because it was so close to the “real thing”. Then there are all the people who use the process to produce extremely accurate moulds with no costly machining to worry about. It’s suitable for a wide range of moulding processes including direct casting moulds in metal or polyurethane and investment cast pattern moulds, sand casting, RTV moulding and thermoforming, among others. In fact, the system is now being used by most of the big names in the industry, simply because it cuts so much time out of the production equation. Investment casting, by the way, means a (usually) metal part produced from a mould that was created by surrounding an expendable pattern with a ceramic slurry. It offers a very smooth surface finish with intricate design and detail possible. The dimensional accuracy is very high – in the order of ±.002cm/cm. More information? SOS Components offer a free CD which contains an extensive library of 3D models as well as explanation on how the processes work. They are located at 30 Paradise St, Banyo, Qld (on Brisbane’s northside, not far from Brisbane airport). Phone no is (07) 3267 8104. Website is www.3dprinting.com.au SC siliconchip.com.au SILICON CHIP Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 www.siliconchip.com.au PRICE GUIDE: SUBSCRIPTIONS YOUR DETAILS (Note: all subscription prices include P&P). (Aust. prices include GST) Your Name________________________________________________________ (PLEASE PRINT) Organisation (if applicable)___________________________________________ Please state month to start. 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Card expiry date: Signature_____________________________ SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS* * except subscriptions/renewals Qty Item Price Item Description Subscribe to SILICON CHIP on-line at: www.siliconchip.com.au Both printed and on-line versions available Total TO PLACE YOUR ORDER siliconchip.com.au P&P if extra Total Price BUY MOR 10 OR ISSU E BACK ES A 1 0 & G ET DISC % OUN T $A Phone (02) 9939 3295 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9939 2648 with your credit card details 24 hours 7 days a week OR Mail this form, with your cheque/money order, to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW, August Australia 20972008  17 08/08 TekTronix DPO3034 Digital Phosphor Oscilloscope Review by Mauro Grassi The 300MHz DPO3034, with its wide “digital phosphor” LCD screen, is a serious oscilloscope with an impressive list of features and an excellent user interface. T he TekTronix DPO3034 is an impressive oscilloscope with the latest version of Tek’s “digital phosphor” screen and advanced features like extended MATHs functions and waveform replay, zoom and search. Its bandwidth is 300MHz and the sampling rate is 2.5Gs/s for each individual channel. With some 4-channel oscilloscopes, the sampling rate is shared among the channels or pair of channels. This means that the effective sampling rate is frequently half that of the quoted specification, when all channels are in use. However, this oscilloscope achieves 2.5GS/s on each channel at all times. The vertical resolution of the digitising system is 8 bits and the sensitivity is better than most comparable oscilloscopes, ranging from 1mV/div to 10V/div. Phosphor display This scope has the latest version of Tek’s so-called “digital phosphor” display. The colour screen is a 228mm (9-inch) (diagonal) WVGA (wide VGA: 18  Silicon Chip Specifications at a glance: Input channels:..... ... 4 Analog Bandwidth: .... DC to 300MHz Sampling Rate:..... ... 2.5GS/s at all tim es for each channe Memory Depth:..... l ... 5Mpts Vertical Sensitivit y:... 1mV/div to 10 V/div Vertical Resolutio n:.. 8 bits LCD Screen:........ ... WVGA (800x480 pixels) Screen size:........ .... 22.8mm (9-inch ) diag Weight:.............. ... 4.2kg 800 x 480 pixels) LCD that looks bright and shows good contrast. The display refresh rate is fast at 50kHz. The screen emulates the desirable features of the phosphors used in analog oscilloscopes employing CRTs (Cathode Ray Tubes). The intensity of the traces can be varied over a wide range while the persistence time can be selected from periods ranging from 10 seconds down to milliseconds. This is useful when you have fast glitches or you are using single step triggering. Interestingly, the display has a wide screen aspect ratio and is 198mm wide by 120mm high (1.65:1). This allows you to see more time domain data and effectively gives you the advantage of an even larger screen. Replay and review waveforms One of the best features of this oscilloscope is its ability to capture and replay waveforms. This feature is part of the so-called Wave Inspector module. It has a zoom and pan control knob that allows you to search and mark the waveform data by comparing it to a preset trigger pattern. Its deep memory of 5Mpts (million points) means that at a reasonable resolution acquisition rate of say 100Kpts you can capture almost a minute of waveform data. Wave Inspector then allows you to mark and search waveforms. You may be interested in a small portion of a waveform, one that may occur relatively infrequently yet occurs very quickly. While having a deep memory is essential, it is also essential to be able to search that large memory. The search feature functions much like a trigger except that it is applied to an already acquired waveform rather than a real time waveform. There is the added advantage that once the data has been captured you can try different searches. You may then mark the relevant points where the search found the trigger and go back to it or scroll back and forth between saved markers. A screen grab showing the Wave Inspector is shown in Fig.1. You can also pan and zoom in on parts of the captured waveform to insiliconchip.com.au spect it in closer detail. These features make the DPO3034 a very powerful debugging tool. Advanced triggering As is usual in current oscilloscopes, the trigger can be AC or DC-coupled or low or high pass filtered to reduce spurious noise. The standard triggering modes of the DPO3034 include the usual edge and pulse triggering modes as well as standard video triggering (NTSC, PAL, SECAM). For the newer HD (high definition) TV formats however, the DPO3034 must be upgraded with an optional module. The DPO3034 also has some advanced triggering modes, one of which is sequential triggering. This mode allows you to select a primary trigger and a secondary trigger. The triggering will occur only if the primary trigger occurs followed by the secondary trigger. Normally the two triggers would take their input from different channels. Optional modules Application modules are available to enhance the DPO3034. These are siliconchip.com.au unlocked by purchasing an additional licence. For example, there are modules to decode serial protocols like I2C, RS232/485, LIN, CAN and SPI as well as for the HD TV formats, as mentioned previously. The serial protocol modules are especially useful if you are debugging an embedded application. It is common to find a few different serial busses operating concurrently even if all you are using is a small microcontroller. In Fig.2 we show the result of decoding an RS232 stream using the optional module. The DPO3034 also includes, for the serial protocols, an event table, shown in Fig.3. This is a log of the relevant decoded data in chronological order. These modules are implemented as small “cards” that plug into one of four ports on the front of the oscilloscope. The automotive serial protocols CAN/LIN are separate to the data protocols, so you will need two different modules if you want all of these. Considering that many cars use both CAN and I2C this could have been better offered as a single module, especially since the number of upgrade ports is limited to four. Unfortunately, you cannot trigger on these serial events or on the optional video formats unless the module is installed. Some oscilloscopes allow you to trigger on serial protocols and only the decoding is optional. For the DPO3034 you need the module for both triggering and decoding. For modules not installed in your oscilloscope, there is a 30-day free trial activated when you first use your oscilloscope. Probes The DPO3034 and other oscilloscopes in this range are supplied with one 500MHz passive probe per channel. Each of the four BNC inputs has auto-sensing and can also provide power for active probes. In fact, the DPO3034 can provide up to 20W of power for active probes. August 2008  19 Fig.1: this shows the Wave Inspector enabled. Having captured an audio stream, we can zoom in and “play” it back. The small white triangles visible at the top of the bottom window indicate the edge trigger events (the triggering was set to a falling edge at 0.0V and the audio stream is AC coupled). You can then pan across from one marked event (trigger) to the next inspecting the captured waveform data. Apart from the usual passive probes, you can optionally use current sensing and differential probes. The input impedance of each channel can be selected from 1MW, 75W or 50W. The 50W input impedance is useful for RF circuit analysis, while 75W is used for TV or video work. The DPO3034 incorporates in-built 75W terminators that will be appreciated by video technicians, as this is not commonly found in oscilloscopes. Each channel can be AC or DC coupled and bandwidth limited to 150MHz or 20MHz. In general you should use the lowest bandwidth which will still give optimum resolu- tion. Any higher bandwidth will just add noise to the signal. MATHs features The MATHs features of this oscilloscope are exceptionally good. You can do real-time FFT analysis on a signal but you can also define a general mathematical expression and display it as a trace on the screen in real time. In Fig.4 we show the result of using the MATHs function to compute, in real time, the gain-bandwidth product of an op amp. Maths waveforms can be created from real time channel data or from previously stored reference wave- Fig.5: a Triac controlling a mains light using phase control. We have used a 100:1 probe to monitor the A1 output of the Triac (green trace) and the vertical scale stands at 200V/div. The cycle RMS measurement for this channel shows 218V and the duty stands at 72%. Also shown is the gate pulse used to turn on the Triac through an optocoupler (pink trace). The positive pulse width of the gate turn on is measured to be 140.4us. 20  Silicon Chip Fig.2: a decoded RS232 stream from a microcontroller as the B1 trace (purple). The data format is set to 8 bits, no parity and one stop bit, while the baud rate is set at 9.6Kbps. The decoded data is shown as a hexadecimal byte (0xE2) and the triggering occurs on the start bit. Custom baud rates are also allowed for non-standard systems. The input to the decoder is shown as the yellow trace, which is channel 1. forms. You can also inspect the maths waveforms like any other waveform. You can use a maths waveform to estimate the power consumption of a circuit or integrate a waveform to estimate the brightness of a light source driven in switchmode. Fig.5 shows the result of measuring the output of a Triac in switchmode. Making measurements All the usual measurements of a waveform can be made: RMS, frequency and peak-to-peak voltage etc. You can also capture a “snapshot” of a waveform. In this case, all measurements will be taken simultaneously. Fig.6: the OpenChoice PC software supplied free-of-charge with the oscilloscopes in this series. It allows you to record your work with the oscilloscope and store important settings. Interface with the oscilloscope is via the USB port (connecting cable supplied). Other software is also supplied. siliconchip.com.au Fig.3: the event table associated with the serial stream shown in Fig.2. The single byte of data is shown in the table and the time relative to the trigger point (155.6us) chronicles the activity on the channel. The event table can be exported to a computer for storage or further analysis either by saving to the on board non-volatile memory and transferring later to a PC or by saving to a USB flash disk connected to the host port on the front. You can also customise an automatic measurement. For example, gating is the name given to restricting measurements on a waveform to a specific portion. With gating enabled, you can restrict the chosen measurement to within the visible screen area or to within the area designated by cursors. Measurement indicators can be turned on and switched off. This allows you to see on the display the actual part of the waveform that the displayed measurement corresponds to. It can be considered a kind of automatically set cursor. Cursors can also be used for manual measurements on stored or real time waveforms, including the output of the MATHs function. Connections & software The DPO3034 has all the connections you would expect as standard: a built in ethernet port, USB 2.0 device and host ports and video output for connecting an external monitor. A variety of PC software is supplied with the scope. OpenChoice software shown in Fig.6 allows you to save screen grabs and settings. The settings can then be recalled at a later time. There is also data logging software supplied, NI LabView SignalExpress which allows you to remotely control the oscilloscope using an ethernet, USB or GPIB port. You can, for example, obtain a live waveform display from the oscilloscope through your network, and by extension, through a siliconchip.com.au Fig.4: the MATHs function (red trace at top of screen) used to compute the gain-bandwidth product of an amplifier. The input is a sinewave at around 3kHz and 1.5V RMS (yellow trace). The gain is computed by dividing the amplitude of the output (cyan trace) by the input. We then multiply this by the real time measurement of the input frequency. The measured mean of the result is around 38,900. range of inter-networks. NI LabView SignalExpress software can also produce statistical reports including histograms and can be used for limit testing. Limit testing refers to the procedure for measuring the limit-cases (ie, the maximum and minimum levels) and is useful for rating a design and ascertaining the best and worst cases for operation. For example, what’s the absolute maximum current drawn and power dissipated by a circuit? Conclusion The DPO3034 is a serious oscilloscope with an impressive list of features and an excellent user interface. We have very few negative things to say about this oscilloscope. The user interface sometimes is slow to respond to changes in settings. However, this only occurs at certain points in the menus and does not affect the waveform display when running. The Auto Set feature can take up to five seconds which is slow compared to other oscilloscopes. However, it is still much shorter than if you had to change all the relevant settings manually. On the other hand, the user interface of the DPO3034 and what you can do with it is among the best we have seen in comparably priced oscilloscopes. The general MATHs features are powerful. The ability to make automatic and custom measurements and to search, zoom in on and play back waveforms makes this oscilloscope a desirable debugging tool. It has an attractive screen and many connection options as standard. The DPO3034 is supplied with four 500MHz passive probes, manuals and NI LabView SignalExpress and Open Choice PC software. The price of this particular model is $9832.00 (ex GST). Other oscilloscopes in this Tektronix range are priced from $5680 (2 channels, 100MHz) to $13960.00 (4 channels, 500MHz). The optional modules are priced at $1265.00 (I2C/SPI decoding and triggering), $1265.00 (CAN/LIN decoding and triggering), $1265.00 (RS232C/ RS422/485 decoding and triggering) and $799.00 (HD TV decoding and triggering). It can be purchased from Tekmark Australia, Suite 302, 18 Orion Rd Lane Cove, NSW 2066. Phone: (02) 9911 3888 or visit www.tekmark.net.au SC A NOTE TO SILICON CHIP SUBSCRIBERS Your magazine address sheet shows when your current subscription expires. Check it out to see how many you still have. If your magazine has not turned up by the first week of the month, contact us at silchip<at>siliconchip.com.au August 2008  21 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 Ultra-LD Mk.2 200W Power Amplifier A new class-AB design with ThermalTrak Power Transistors This new amplifier module supersedes both the Plastic Power module described in the April 1996 issue and the Ultra-LD module presented in the March 2000 issue. It produces high power at very low distortion. In fact, as far as we are aware, it is the lowest distortion class-AB amplifier that has ever been published. Pt.1: By LEO SIMPSON & JOHN CLARKE 24  Silicon Chip siliconchip.com.au Specifications & Performance Output Power: 200 watts RMS into 4W; 135 watts RMS into 8W Frequency Response at 1W: -3dB at 4Hz, -1dB at 50kHz (see Fig.4) Input Sensitivity: 1.26V RMS for 135W into 8W Input Impedance: ~12kW Rated Harmonic Distortion: < .008% from 20Hz to 20kHz for 8W operation; typically < .001% (see Figs.5-8) Signal-to-Noise Ratio: 122dB unweighted with respect to 135W into 8W (22Hz to 22kHz) Damping Factor: <170 with respect to 8W at 100Hz; <50 at 10kHz Stability: Unconditional T HE ULTRA-LD MK.2 AMPLIFIER Module uses the new On Semiconductor ThermalTrak power transistors in a circuit which is largely based on our high-performance Class-A amplifier which was featured in SILICON CHIP during 2007. The ThermalTrak transistors are a new version of the premium MJL3281A & MJL1302A and have an integral diode for bias compensation. As a result, the circuit has no need for a quiescent current adjustment or a “Vbe multiplier” transistor. This is also our first amplifier module to use a double-sided PC board. Ostensibly, there is no reason to use a double-sided board for a relatively simple circuit such as this, especially as our previous single-sided amplifier boards have had few links. In fact, we have used the doublesided design to refine and simplify the external wiring to the PC board which has been arranged to largely cancel the magnetic fields produced by the asymmetric currents drawn by each half of the class-B output stage. We provide more detail on this aspect later in this article. Power output of the new module is on a par with the above-mentioned Plastic Power module and significantly more than the original Ultra-LD module. As well, it uses a considerably simpler power supply than the UltraLD module. Power output is 135 watts RMS into an 8-ohm load and 200 watts into a 4-ohm load for a typical harmonic distortion of less than .001%. The new module also has slightly higher gain than the Ultra-LD module but siliconchip.com.au Design Features • • • • Very Low Distortion No adjustment for quiescent current required Double-sided PC board simplifies wiring PC board topology cancels class-B induced magnetic fields still manages to produce an improved signal-to-noise ratio of -122dB (unweighted) with respect to 135W into 8W. This is extremely quiet. A look at the accompanying performance panel and the performance graphs will show that this is a truly exceptional amplifier, bettered only by the Class-A amplifier described during 2007. In fact, some of the distortion figures we have obtained are so low, around .0007% for operation into 8-ohm loads, that we were amazed. We had expected this Class-AB amplifier to be better than anything we had published before – but not this good! Circuit description Fig.1 shows the full circuit of the new amplifier. As already mentioned, the front end of the circuit (ie, all except the output stages) is based on the Class-A amplifier published in May 2007 and subsequent issues. While the general configuration was designed to optimise performance of the Class-A design, it provides similar benefits to Class-AB operation, such as low residual noise and excellent power supply rejection ratio (PSRR). We have already mentioned that there is no need for a “Vbe amplifier” stage and no quiescent current adjustment. Also the complementary-feedback pair (CFP) power output stage of the original Ultra-LD module has been discarded in favour of a more conventional complementary-symmetry Darlington emitter follower stage. So let’s go through the circuit in detail. The input signal is coupled via a 47mF non-polarised (NP) electrolytic capacitor and 100W resistor to the base of transistor Q1. This is one of the input differential pair (ie, Q1 & Q2) using Toshiba 2SA970 PNP low-noise transistors which are responsible for the very low residual noise of the amplifier. The 100W input resistor and 820pF capacitor constitute a low-pass filter with a -6dB/octave rolloff above 1.9MHz. This is a much lower impedance network than our previous designs, in order to provide the lowest impedance for the signal source. Both the bias resistor for Q1 and the series feedback resistor to the base of Q2 are set at 12kW (instead of 18kW in the original Ultra-LD and Plastic Power designs), again to minimise source impedance and thereby, Johnson noise. The gain of the amplifier is set by the ratio of the 12kW and 510W feedback resistors to a value of 24.5, while the low-frequency rolloff (-3dB) of the gain is set by the 220mF capacitor to 1.4Hz. Feedback capacitors Some readers may wonder why we used such large electrolytic capacitors in the input and feedback networks. The answer is that we are acting to eliminate any effects of capacitor distortion in the audio pass-band and as noted above, to minimise the source impedance “seen” by the input transistors. To explain this point, consider that the typical source impedance of a DVD or CD player is only a few hundred ohms. If we use a much smaller input capacitor, say 2.2mF, its impedance will be 1447W at 50Hz. This will only have a small effect on the frequency response but represents a very large increase in the source impedance “seen” by the input stage. By contrast, the 47mF input capacitor will have an impedance of only 67W. August 2008  25 26  Silicon Chip siliconchip.com.au 210mV Q3 BC546 A K E C 820pF D1, D2: 1N4148 12k B B E C 100nF B Q1, Q2: 2SA970 68 C E E C A K 68 A D1 470 F 63V 210mV Q4 BC546 D2 B 100 47 F 35V 2.2k K B 2.2k B 12k B B Q8 BC639 E C E K K A A K K A A Q7 BF470 Q9 BF469 C C E 47 2SA970, BC639 E C 22k 100nF 2.2k 54.3V 220 F 16V 510 6.2k 6.2k B 100pF 100V C E ULTRA-LD MK.2 200W AMPLIFIER MODULE 10 1M 100 6.8k 1W B 47 F 35V 2.2V B C B C B 7-10 mV Q14 NJL1302D 0.1  7-10 5W mV E B Q13 NJL3281D FUSE1 5A C E B C FUSE2 5A Q15 NJL1302D B 0.1  7-10 5W mV E C BF469, BF470 Q11 MJE15031 C E 100 7-10 mV B Q12 NJL3281D 100 E C 10  1W B B Q10 MJE15030 BC546, BC556 54V 100 DQ15 DQ14 DQ13 DQ12 E 54V 100 100nF 100nF E 1000 F 63V C B E 390  1W –55V (NOM.) 0V SPEAKER OUT PHONES OUT CA K NJL3281D, NJL1302D 1000 F 63V 150nF 400V 6.8  1W L1 6.8 H MJE15030, MJE15031 100nF 0.1  5W 0.1  5W C E E C +55V (NOM.) Fig.1: the circuit employs the new ThermalTrak power transistors from On Semiconductor. These have an integral diode which is used to control the quiescent in the Class-B output stage. The four diodes are shown separately on this circuit (ie, DQ12, DQ13, DQ14 & DQ15) for clarity but are actually integral with the output transistors which have five connecting leads instead of three. Note that the various voltages marked on the circuit will vary according to the supply rails. 2008 SC  COM SIGNAL IN 47 F NP C 100 43V Q5 BC556 E 100 Q6 BC556 Parts List 1 double-sided PC board, code 01108081, 135 x 115mm 1 heatsink, 200L x 75mmH x 46Dmm 4 M205 PC-mount fuse clips (F1,F2) 2 5A M205 fast-blow fuses 1 6.8mH air-cored inductor (L1) (or 1 20mm OD x 10mm ID x 8mm bobbin and 1.5m length of 1mm enamelled copper wire) 2 3-way PC-mount screw terminals, 5.08mm spacing (Altronics P 2033A) (CON2, CON3) 1 2-way PC-mount screw terminals with 5.08mm spacing (Altronics P 2032A) (CON1-CON3) 2 TO-220 mini heatsinks, 19 x 19 x 9.5mm 2 TO-220 silicone insulating washers 4 TO-264 ThermalTrak silicone insulating washers 2 transistor insulating bushes 4 M3 tapped x 9mm standoffs 6 M3 x 20mm screws 2 M3 x 10mm screws Readers might also wonder why we have not used a non-polarised (NP) electrolytic for the 220mF capacitor in the feedback network since this is normally preferable where the capacitor’s operating voltage is extremely low. The answer is that an NP electrolytic could have been used except for its greater bulk and we wanted to minimise any extraneous signal pickup which could happen with a physically larger capacitor. Extraneous signal pickup is one of the unwanted side-effects of a much wider frequency response – the amplifier is more prone to EMI and in the extreme case, to supersonic oscillation, if the wiring details are not duplicated exactly. Diodes D1 & D2 are included across the 220mF feedback capacitor as insurance against possible damage if the amplifier suffers a fault which pegs the output to the -55V rail. In this circumstance, the loudspeakers would be protected against damage by a loudspeaker protection module (such as that published in the July 2007 issue of SILICON CHIP) but the siliconchip.com.au 8 M3 x 6mm screws 8-M3 nuts Semiconductors 2 2SA970 PNP transistors (Q1, Q2) 2 BC546 NPN transistors (Q3,Q4) 2 BC556 PNP transistors (Q5,Q6) 1 BC639 NPN transistor (Q8) 1 BF470 PNP transistor (Q7) 1 BF469 NPN transistor (Q9) 1 MJE15030 NPN transistor (Q10) 1 MJE15031 PNP transistor (Q11) 2 NJL3281D NPN ThermalTrak transistors (Q12,Q13) 2 NJL13020D PNP ThermalTrak transistors (Q14,Q15) 2 1N4148 switching diodes (D1,D2) Capacitors 2 1000mF 63V PC electrolytic 1 470mF 63V PC electrolytic 1 220mF 16V PC electrolytic 2 47mF 35V PC electrolytic 1 47mF NP electrolytic 220mF capacitor would be left to suffer reverse current. Note that we have used two diodes here instead of one, to ensure that there is no distortion due to the non-linear effects of a single diode junction at the maximum feedback signal level of about 1V peak. Voltage amplifier stage Most of the voltage gain of the amplifier is provided by Q9 which is fed via emitter follower Q8 from the collector of Q1. The emitter follower transistor is a BC639 which has higher ratings than the BC546 used for this function in the Class-A amplifier. It is used to buffer the collector of Q1, to minimise non-linearity. Q9 is operated without an emitter resistor to maximise gain and its output voltage swing. We need to maximise voltage swing from the voltage amplifier stage in order to obtain the maximum power output from the output stages. The collector loads for Q1 & Q2 are provided by current mirror transistors Q3 & Q4. Similarly, the collector load 1 150nF 400V MKT polyester 5 100nF 63V MKT polyester 1 820pF ceramic 1 100pF 100V ceramic (eg, Altronics R 2882) Resistors (0.25W, 1%) 1 1MW 8 100W 2 12kW 2 68W 1 22kW 1 47W 1 6.8kW 1W 1 6.8W 1W 2 6.2kW 1 10W 3 2.2kW 1 10W 1W 1 510W 4 0.1W 5W 1 390W 1W 2 0W 2 68W 5W (for testing) Transistor Quality To ensure published performance, the 2SA970 low-noise transistors (Q1 & Q2) must be from Toshiba. Be wary of counterfeit parts, as reported by us in the past. All other transistors should be from reputable manufacturers, such as Philips (NXP Semiconductors), On Semiconductor and ST Microelectronics. This applies particularly to the MJE15030 & MJE15031 output driver transistors. for Q9 is provided by a constant current load comprising transistors Q6 & Q7. Interestingly, the base bias voltage for constant current source Q5 is also set by Q6. Q5 is the constant current “tail” for the input differential pair and it sets the collector current through these transistors. The reason for the rather complicated bias network for Q5, Q6 and Q7 is to produce a major improvement in the power supply rejection ratio (PSRR) of the amplifier. Similarly, the PSRR is improved by the bypass filter network consisting of the 10W 1W resistor and 470mF 63V capacitor in the negative supply rail. Why is PSRR so important? Because this amplifier runs in class-B, it pulls large asymmetric currents which can be 9A peak or more, from the positive and negative supply rails. Let’s explain this. When the positive half of the output stage (Q12 & Q13) conducts, the DC current drawn is effectively the positive half-wave of the signal waveform, ie, rectification takes place. Similarly, when the negative half of the output stage (Q14 & Q15) August 2008  27 +Vcc CURRENT SOURCE Q10 Q13 Q12 DQ12 DQ13 0.1 0.1 0.1 0.1 2.2V DQ14 DQ15 Q14 Q9 Q15 Q11 –Vcc Fig.2: this schematic demonstrates how the four integrated diodes of the output transistors set the quiescent operating conditions of the Darlington emitter follower output stage. Note that the voltage drop across each diode is quite low at round 0.55V. conducts, the DC current is the negative half wave of the signal. So we have half-wave rectification ripple of the signal superimposed on the supply rails, as well as the 100Hz ripple from the power supply itself. And while the PSRR of an amplifier can be very high at low frequencies, it is always poorer at the high frequencies. So what happens is that these nasty ripple voltages inevitably get into the earlier stages of the amplifier and cause distortion. Which is why we need to keep these ripple voltages to a minimum. That is why we employed separate regulated high-voltage supply rails for the original Ultra-LD amplifier. However, the extra filtering we employed in the Class-A amplifier (using techniques suggested by Douglas Self) now performs much the same function in this new Class-AB amplifier module so that we can dispense with the regulated supplies. The scope grab on page 30 in this article gives a graphic demonstration of the signal rectification phenomenon we have just described. The centre (yellow) trace shows a 1kHz sinewave output signal from the amplifier at 100W into an 8-ohm load. The top (red) trace shows the ripple on the positive supply. 28  Silicon Chip Note the large 100Hz sawtooth component which is ripple from the power supply. Superimposed on this is the half-wave rectified signal frequency at 1kHz. The bottom (blue) trace shows the same process on the negative supply rail. The 100pF capacitor between the collector of Q9 and the base of Q8 sets the open-loop bandwidth of the amplifier. Since it is subject to the full output voltage swing of the voltage amplifier stage, it must have a rating of 100V or more. Output stage The output signal from the voltage amplifier stage Q9 is coupled to driver transistors Q10 and Q11 via 100W resistors. These protect Q7 and Q9 in the event of a short circuit to the WARNING! High DC voltages (ie, ±55V) are present on this amplifier module when power is applied. In particular, note that there is 110V DC between the two supply rails. Do not touch the supply wiring (including the fuseholders) when the amplifier is operating, otherwise you could get a lethal shock. amplifier output which could possibly blow these transistors before the fuses blow. The 100W resistors also have a secondary function in acting as “stopper” resistors to help prevent parasitic oscillation in the output stage. As already mentioned, the output stage uses complementary Darlington transistor pairs rather than the complementary feedback pairs (CFP) used in the previous Ultra-LD module and the Class-A modules. There are two reasons for this approach. First, we are using the highly linear ThermalTrak output transistors with their integral bias compensation diodes. To take advantage of these diodes we need to employ Darlington emitter followers, as will be explained in a moment. Second, a CFP output stage does not give good current sharing between the paralleled output transistors and we wanted this in order to make this new Ultra-LD Mk.2 suitable for delivering full power into 4-ohm loads. Bias compensation With four Thermaltrak power transistors used in the output stage, we have four integrated diodes available for bias compensation. As shown on the circuit, the four diodes are connected in series between the collector of Q7 and the collector of Q9. Some readers may be aware that this arrangement, together with an adjustable series resistor, was a common method for setting the output quiescent current, before the “Vbe multiplier” became the standard method over 30 years ago. Now for a given bias setting in any Class-B amplifier, the base-emitter voltage in the output transistors will drop with a rising temperature. So as the output transistors heat up, they draw more current which makes them hotter and soon you have “thermal runaway” and eventual transistor destruction. Since the bias setting for the output stage transistors is set by the voltage drop across the four integrated diodes, there is little chance of thermal runaway. Not only are the diodes matched to the base-emitter junctions of the transistors, they are also on the same die (chip) so the tracking between the two is very close. This is a great advantage over a Vbe multiplier transistor mounted on the heatsink because the latter arrangement inevitably has a considerable thermal lag which can be as much as siliconchip.com.au MJE15030 MJE15031 BF470 L1 6.8  1W 10  1W 100pF 100V 12k 6.8 H 390  1W BF469 Q9 6.2k NJL1302D 18080110 FUSE 2 (5A) reifilpmA 2.KM DL-artlU 0.1  5W 100 100nF Q7 2.2k 1000 F 63V Q5,Q6: BC556 2.2k Q5 Q6 100nF 100nF 6.8k 1W 100 100 100 47 F 35V 47 F 47 0.1  5W 0.1  5W FUSE 1 (5A) 6.2k 100nF Q15 NJL1302D Q11 Q10 1000 F 63V Q14 0.1  5W NJL3281D 100 Q13 NJL3281D 2.2k Q12 2 x 2SA970 0 510 0 12k 1M 47 F NP 820pF 220 F 10 D1 4148 4148 D2 Q8 Q3 Q4 CON2 BC639 2 x BC546 470 F 63V 100nF 150nF 400V 100 68 100 Q1 Q2 68 100 CON3 SPEAKER + SPEAKER – PHONES OUT 22k CON1 SIG COM +55V 0V –55V Fig.3: the PC board parts layout of the new amplifier module. The double-sided design allows much better cancellation of magnetic fields due to the asymmetric currents in the output stage. 30 minutes (depending on the size of the heatsink). With the Thermaltrak transistors, we don’t have to worry about thermal lag or runaway. The quiescent current settles quickly at switch-on. Thereafter, it can drift about, depending on the supply voltage and signal conditions but it will always come back to the initial “no-signal” value. On Semiconductor also claim that the harmonic distortion of the amplifier is lower than it would be with a Vbe multiplier stage. Fig.2 shows the method of setting the output quiescent current. As depicted here, the four integrated diodes compensate for the four base-emitter junctions which control the quiescent current in the output stage. These are the two base-emitter junctions in the driver stages (Q10 & Q11) and the two paralleled base-emitter junctions of the four output transistors (Q12, Q13 & Q14, Q15). The quiescent current is set by the difference in voltage drops between the aforementioned base-emitter juncsiliconchip.com.au tions and the four diodes and this voltage difference appears across the 0.1W emitter resistors of the output. Typically, the voltage across the emitter resistors will be around 7-10mV, giving a quiescent current of around 70-100mA for each transistor; somewhat higher than we would have set with a Vbe multiplier. Output RLC filter The remaining circuit feature to be discussed is the output RLC filter, comprising a 6.8mH air-cored choke, a 6.8W resistor and a 150nF capacitor. This output filter was originally produced by Neville Thiele and is still the most effective output filter for isolating the amplifier from any large capacitive reactances in the load, thereby ensuring unconditional stability. It also helps attenuate any RF signals picked up by the loudspeaker leads and stops them being fed back to the early stages of the amplifier where they could cause RF breakthrough. Note that if the amplifier is intended for an application that requires continuous high-power output at frequencies of 10kHz or more, then the 6.8W resistor will need to be a 5W or 10W wirewound resistor. Fuse protection The output stages are fed via 5A fuses from the ±55V rails. These provide the only protection to the amplifier against short-circuits or other failures which could cause high current drain. Note that we recommend the use of a loudspeaker protector such as the one described in the July 2007 issue of SILICON CHIP. Double-sided PC board As already noted, a double-sided PC board is used to simplify the power supply wiring. The general layout of the PC board is very similar to that used in the SC480 amplifier featured in the January & February 2003 issues which was itself a refinement of the layout used in the original Ultra-LD module. As such, the PC board has two important features. August 2008  29 Audio Precision Frequency Response 8 Ohm (1W) 07/04/08 08:03:15 Fig.4: frequency response at 1W into 8 ohms. While the minimum frequency shown here is 10Hz, the response extends well below that to around -3dB at 4Hz. First, it has “star earthing” whereby all earth (0V) currents come back to a central point on the board, thereby avoiding the possibility of output, supply and filter bypass currents flowing in the sensitive signal earth return conductors. More importantly, the placement of Audio Precision THD vs Power 8 Ohm Fig.5: total harmonic distortion versus power at 1kHz into to an 8-ohm resistive load. Maximum power at the point of clipping is 135W. heavy copper supply and earth tracks on the board is arranged to cancel the magnetic fields produced by the asymmetric currents drawn by each half of the output stage. In the aforementioned amplifiers, we arranged this cancellation by having the main supply leads to the module lie closely This scope grab gives a graphic demonstration of the signal rectification phenomenon in the Class-B output stage. The centre (yellow) trace shows a 1kHz sinewave output signal from the amplifier at 100W into an 8-ohm load. The top (red) trace shows the ripple on the positive supply. Note the large 100Hz sawtooth component which is ripple from the power supply. Superimposed on this is the half-wave rectified signal frequency at 1kHz. The bottom (blue) trace shows the same process on the negative supply rail. 30  Silicon Chip 07/04/08 10:48:58 underneath the respective tracks on the PC board. While this arrangement works well, if it is to be effective it depends on the constructor following the wiring diagram very closely. The PC board layout is shown in Fig.3. To visualise how the field cancellation occurs, consider how the positive rail fuse (Fuse1) is placed close and parallel to the emitter resistors for Q12 & Q13. So the magnetic field produced by the half-wave currents in Fuse1 are more or less cancelled by the same current flowing back through the emitter resistors. The same mechanism applies with Fuse2 in the negative rail and the emitter resistors for Q14 & Q15. Now consider the two heavy tracks which carry the positive and negative supply rails from the connector CON2 up the centre of the PC board and then diverge at rightangles to the two fuses, Fuse1 & Fuse2. Directly under the diverging supply tracks are the tracks which connect the pairs of emitter resistors together to connect them to the output via the RLC filter. Almost complete magnetic field cancellation takes place because of this track arrangement. Finally, the main earth (0V) return track to CON2, underneath the board, cancels the magnetic field produced by the main supply tracks running on the top centre of the board. By the way, merely twisting the positive and negative supply wires of a classB amplifier together gives no magnetic siliconchip.com.au Audio Precision THD vs Power 4 Ohm 07/04/08 08:54:09 Fig.6: total harmonic distortion versus power at 1kHz into a 4-ohm resistive load. Maximum power at the point of clipping is 200W. field cancellation at all in the absence of the return earth. Why? Simply because the positive half-wave currents do not occur at the same time as the negative half-wave currents. To sum up, the Class-B magnetic field cancellation technique employed is important because it greatly reduces the overall harmonic distortion of the amplifier. In the SC480 module, it produced good results from ordinary power transistors. In this design, with a double-sided PC board complementing the new very linear ThermalTrak power transistors and special filtering of the supply rails, the results are very much better. Finally, we need to clear up a few points. At various times we have referred to this amplifier as operating in class-B and in class-AB. Strictly speaking, the amplifier operates in class-AB, ie, a mixture of class-A which means that a constant current flows in the output stage and class-B which refers to the separate operation of the positive and negative sections of the output stage. Audio Precision THD+N vs FREQ 8 Ohm (100W) 07/04/08 08:24:27 Fig.7: total harmonic distortion versus frequency into an 8-ohm resistive load. This is measured with a bandwidth of 10Hz to 80kHz. Audio Precision THD+N vs FREQ 4 Ohm (100W) 07/04/08 08:40:33 Coming next month Next month, we will describe the assembly of the module and give the test procedure. We’ll also describe a suitable SC power supply. Fig.8: total harmonic distortion versus frequency at 100W into to a 4-ohm resistive load, measured with a bandwidth of 10Hz to 80kHz. into MOTORS/CONTROL? Electric Motors and Drives – by Austin Hughes Fills the gap between textbooks and handbooks. Intended for nonspecialist users; explores all of the widely-used motor types. $ 60 Practical Variable Speed Drives – by Malcolm Barnes An essential reference for engineers and anyone who wishes to or use variable $ 105 design speed drives. AC Machines – by Jim Lowe Applicable to Australian trade-level courses including NE10, NE12 and parts of NE30. Covers all types of AC motors. $ 66 DVD Players and Drives – by KF Ibrahim DVD technology and applications with emphasis on design, maintenance and repair. Iideal for engineers, technicians, students, instal$ 95 lation and sales staff. There’s something to suit every microcontroller motor/control master maestroininthe the SILICON CHIP reference bookshop: see the bookshop pages in this issue Performance Electronics for Cars – from SILICON CHIP 16 specialised projects to make your car really perform, including engine modifiers and controllers, $ 80 instruments and timers. 19 Switching Power Supplies – by Sanjaya Maniktala Theoretical and practical aspects of controlling EMI in switching power supplies. Includes bonus CD$ ROM. 115 ! Audio ! RF ! Digital ! Analog ! TV ! Video ! Power Control ! Motors ! Robots ! Drives ! Op Amps ! Satellite siliconchip.com.au August 2008  31 By JIM ROWE A low-cost, easy-to-build Planet Jupiter Receiver How would you like to try some basic radio astronomy – listening to the bursts of noise originating from the planet Jupiter, or from the Sun? You don’t need a lot of fancy equipment to do this, just the simple shortwave receiver described here. It’s hooked up to a basic dipole antenna (which we describe as well) and to the sound card in your PC, so that you can print out “chart recordings” of the noise signals. M ENTION THE TERM “radio astronomy” to most people, and they’ll either look completely blank or visualise huge arrays of steerable dish antennas – like the one at Narrabri in NSW. Of course, a lot of radio astronomy is done nowadays using these big arrays or huge ‘valley sized’ 32  Silicon Chip antennas like the one at Aricebo in Puerto Rico. But it’s still possible to do interesting observations using much simpler antennas and equipment, at “decametric” frequencies (8-30MHz) in the HF radio band. In fact, a NASA-sponsored project called “Radio Jove” has been promot- ing this type of radio astronomy for the last 10 years as a science project for high-school students and interested hobbyists. Over 1000 simple receiver kits have been sold, for 20.1MHz reception of noise bursts from the planet Jupiter, the Sun and other objects in the Milky Way galaxy. siliconchip.com.au There’s only one problem with the US-designed Radio Jove receiver as far as Australian students and hobbyists have been concerned: the receiver kits cost US$155 each plus shipping from the USA, so it will set you back about A$200 to have one sent over here. This has discouraged more than a handful of people in Australia from getting into radio astronomy. To encourage more Australian students and hobbyists to have a go, SILICON CHIP has developed its own low-cost receiver project. And that’s the background to the new receiver described in this article. You’ll find its basic specifications summarised in the “Main Features” panel but the bottom line is that it’s quite suitable for basic radio astronomy at decametric frequencies around 21MHz. This makes it fine for receiving noise bursts from Jupiter, the Sun or other sources in the Milky Way. We estimate that it will cost you around $75 for the basic receiver module, plus $7.30 if you decide to house it in an ABS instrument box. In other words, less than half the cost of the Radio Jove receiver. We also think it is a much better design, by the way. How it works The complete circuit for the receiver is shown in Fig.1. The heart of the circuit is IC1, an SA605D single-chip receiver IC which includes a local oscillator, an RF mixer, a high-gain IF amplifier and an IF limiting amplifier, plus a quadrature detector for FM signal demodulation. We are not using the last of these sections here, because we’re using the SA605 in a slightly unusual way – for AM signal demodulation. We do this by taking advantage of the chip’s RSSI (received signal strength indicator) output from pin 7. This works because associated with the high-gain IF amplifier and limiter stages inside the SA605 are a number of signal level detectors, whose outputs are combined to provide a DC output current from pin 7. This DC output current is logarithmically proportional to the incoming signal strength, so it is essentially an AM detector output. We convert it into a voltage signal by passing the current through a 91kW load resistor, shunted by a 470pF capacitor for low-pass filtering. The centre intermediate frequency (IF) of the receiver is set at 5.5MHz siliconchip.com.au The parts for the Jupiter Receiver are all mounted on a double-sided PC board. The top groundplane pattern is necessary to ensure stability. using ceramic filters CF1 and CF2. These require no alignment. The local oscillator circuit inside IC1 is brought out to pins 3 & 4, to which we connect frequency determining components L3 and VC3, together with 22pF and 39pF capacitors. Together, these components allow the local oscillator to be tuned manually over the range from 25.75-28.0MHz, which is 5.5MHz above the input signal range of interest (20.25-22.5MHz). The use of a 5.5MHz IF means that the receiver’s image frequency will be 11MHz above the wanted frequency – giving a good image rejection ratio. The input of IC1’s mixer stage is tuned to the centre of the wanted frequency band (ie, about 21MHz) by means of inductor L2 and trimmer Main Features The receiver is a single-conversion superhet design tuning from about 20.2522.5MHz, with a sensitivity of approximately 1mV for a 10dB signal-to-noise ratio. Only three controls are provided: RF gain, tuning and audio gain. All components are mounted directly on a small PC board measuring only 117 x 102mm, which can either be used “naked” or housed in a standard low-profile ABS instrument case (140 x 110 x 35mm). The receiver can be powered from either a 12V battery or a mains plugpack supply delivering between 15-18V DC. The current drain is typically between 55-75mA. There are two audio outputs from the receiver: (1) a line output suitable for connection to the line-level input of a PC sound card and (2) a low-impedance output capable of driving external headphones or a small 8W speaker. Both outputs can be used at the same time. August 2008  33 Parts List 1 PC board, code 06108081, 117 x 102mm (double sided, with plated-through holes) 1 plastic case, 140 x 110 x 35mm (optional) 2 Murata 5.5MHz ceramic filters (CF1, CF2) 3 mini RF coil formers (Jaycar LF1227) for L1-L3 1 300m length of 0.25mm enamelled copper wire 1 47mH RF choke (RFC1) 1 68mH RF choke (RFC2) 2 trimmer capacitors, 6.3-30pF (green) (VC1, VC2) 1 miniature tuning capacitor with edgewise knob (VC3) (Jaycar RV-5728) 1 50kW 16mm PC-mount linear pot (VR1) 1 50kW PC-mount 16mm log pot (VR2) 2 16mm-diameter control knobs 1 8-pin DIL socket (for IC2) 2 PC-mount RCA sockets (CON1, CON2) 1 PC-mount 3.5mm stereo jack (CON3) 1 PC-mount 2.5mm concentric DC socket (CON4) 1 TO-220/6093B heatsink 4 M3 x 10mm tapped spacers 5 M3 x 6mm machine screws 5 M3 nuts (two used as spacers for VC1) 2 M2.5 x 5mm machine screws (for VC1) 1 15 x 7mm copper sheet or tinplate (for IC1 shield) 1 14 x 10mm copper sheet or tinplate (for Q1 shield) 1 3.5mm mono jack plug to 3.5mm mono jack plug audio cable Semiconductors 1 SA605D single-chip receiver IC (IC1) capacitor VC2. The ‘Q’ of this circuit is fairly low, so that the receiver’s sensitivity is reasonably constant over the 2MHz wide tuning band. As a result tuning is achieved purely by adjusting the local oscillator frequency. Although the SA605 IC does provide a great deal of gain in the IF amplifier and limiter sections, we have included 34  Silicon Chip 1 LM358 dual op amp (IC2) 1 LM386 audio amplifier (IC3) 1 7812 +12V 3-terminal regulator (REG1) 1 78L05 +5V 3-terminal regulator (REG2) 1 BF998 dual-gate Mosfet (Q1) 1 PN100 NPN transistor (Q2) 1 3mm green LED (LED1) 1 3mm red LED (LED2) 1 1N4004 diode (D1) 1 16V 1W zener diode (optional) Capacitors 1 2200mF 16V RB electrolytic 1 470mF 25V RB electrolytic 1 330mF 16V RB electrolytic 1 22mF 16V tag tantalum 4 10mF 16V RB electrolytic 1 470nF MKT metallised polyester 8 100nF monolithic ceramic 1 47nF MKT metallised polyester 6 10nF monolithic ceramic 7 2.2nF disc ceramic 1 470pF disc ceramic 2 39pF NPO disc ceramic 1 22pF NPO disc ceramic 2 18pF NPO disc ceramic Resistors (0.25W 1%) 2 220kW 2 1.5kW 1 150kW 5 1kW 1 110kW 1 820W 1 100kW 1 360W 1 91kW 1 300W 2 47kW 1 220W 1 22kW 1 100W 1 10kW 1 47W 1 2.2kW 2 10W 1 1.8kW Antenna Parts 1 UB5 plastic box, 83 x 54 x 31mm 1 35 x 21 x 13mm ferrite toroid (Jaycar LO-1238) 50-ohm coaxial cable plus RCA plug for downlead an RF amplifier stage ahead of the IC to ensure that the receiver has adequate sensitivity. As you can see, this RF stage uses a BF998 dual-gate MOSFET (Q1), with the second gate (G2) voltage adjusted via VR1 to allow easy control of RF gain. The RF input signal from the antenna enters the receiver via CON1, and is fed into the input tuned circuit (L1/VC1) via an impedance matching tap on inductor L1. As before, the ‘Q’ of this circuit is kept relatively low, so once it’s tuned to about 21MHz it does not need to be changed. From the RSSI output of IC1, the demodulated audio signals are passed through op amp IC2a (half of an LM358) which is connected as a voltage follower for buffering. They then pass through a simple low-pass RC filter (the 1kW resistor and 10nF capacitor) before being fed to IC2b. This is the other half of the LM358 and is configured as an audio amplifier with a gain of 5.7 times, as set by the 47kW and 10kW feedback resistors. From IC2b, the signals pass through a 470nF coupling capacitor to VR2, the volume/audio gain control. They are then fed through IC3, an LM386N audio amplifier configured here to provide a gain of about 40 times. The amplified audio signals are then coupled via a 330mF output capacitor to speaker output jack CON3 and also to line output socket CON2 via a 1kW isolating resistor. Notice that the buffered RSSI signal from the output of IC2a is also fed to transistor Q2, which is used to drive LED2, the RSSI/overload indicator. Because Q2 does not conduct until the output voltage from IC2a reaches a level of around +2.65V, this means that LED1 really only lights when a very strong signal is being received, ie, when the receiver is tuned to a shortwave radio transmission or some other strong terrestrial signal source. So the main purpose of LED2 is to help you tune AWAY from such signals, rather than to them. Power supply The receiver’s power supply arrangements are very straightforward. Most of the circuitry operates from +12V, which can come directly from a battery if you wish. In this case regulator REG1 is not used but instead replaced by a 10W resistor. The 2200mF capacitor is also replaced by a 16V 1W zener diode, to protect the circuit from damage in case of higher-voltage transients (when the battery is being charged, for example). On the other hand, if you wish to operate the receiver from a 15-18V DC source such as a mains plugpack supply (Americans call them ‘wall warts’), this is very easy to do. In this siliconchip.com.au siliconchip.com.au August 2008  35 S(1) VC1 6-30pF 2.2nF 150k D(2) G1 G2 2x 2.2nF A K 470 F 25V IN GND 2200 F* 16V OUT REG1 7812 A K ZD1* 16V 1W +12V K A  B LED2 RSSI 100k IN GND OUT REG2 78L05  220 LED1 POWER 2.2k K A E C 39pF 39pF 91k 220k 10nF 100nF 100nF 8 47k IC2b 10 F 10k 6 5 8 10 11 470pF 12 100nF 220k 7 RSSI * ZD1 FITTED IN PLACE OF 2200 F CAPACITOR WHEN REG1 IS NOT USED (12V BATTERY OPERATION) 47 100nF +6V RFC2 68 H 1k Vcc 6 +6V IC1 SA605D 13 100nF 10nF 1k 14 LIM IN CF2 5.5MHz 820 17 16 15 IFA OUT 22 F TANT 300 5 MUTE 18 IFA IN 100nF 100nF 19 10nF 1k 10nF 1k RF IN2 LCL OSC B E 4 3 10nF 2 20 1 RF MXR IN1 OUT 10nF L3 1.2 H Q2 PN100 22pF 2.2nF VC2 6-30pF L2 1.8 H 10 F 21MHZ 'PLANET JUPITER' RECEIVER – + D1 1N4004 FIT 10  RESISTOR WHEN REG1 NOT USED (12V BATTERY OPERATION) +12V TUNING VC3 10-120pF 360 18pF 2.2nF 100 RFC1 47 H 1.5k 2 3 7 1 C B E PN100 AUDIO GAIN VR2 50k LOG 470nF 100nF IC2: LM358 4 IC2a 1 6 1 10 F 16V 4 A K OUT LEDS GND IN 7812 7 8 5 10 F 16V 1.5k K A K 1N4004 A ZD1 47nF 16V 10 330 F 1k 8 SPEAKER OUT CON3 AUDIO OUT TO PC CON2 CERAMIC FILTERS CF1 AND CF2 ARE MURATA SFSRA5M50BF00-B0 OR SIMILAR 10 CHAMFER SIDE OUT IC3 2 LM386N 3 +12V NOTCH 20 SA605D IN COM 78L05 Fig.1: the circuit is based on an SA605D single-chip receiver IC (IC1) which includes a local oscillator, an RF mixer, a high-gain IF amplifier and an IF limiting amplifier, plus a quadrature detector for FM signal demodulation. The latter feature is not used here. Instead, the SA605 is used in a slightly unusual way to obtain AM signal demodulation. SC 2008 15-18V (OR 12V) DC INPUT CON4 S D 2.2nF 1.8k Q1 BF998 47k RF GAIN 2.2nF 110k VR1 50k LIN 22k COIL DETAILS: L1, L2 & L3 all on Jaycar LF-1227 3mm diameter mini coil formers using 0.25mm enamelled copper wire, close wound at bottom of former. L1: 20 turns with tap at 4 turns from earth end L2: 20 turns L3: 15 turns NOTE: Ferrite slugs and shield cans are NOT used. 18pF L1 50  1.8 H RF INPUT CON1 G1(4) G2(3) BF998 +12V CF1 5.5MHz ANTENNA INPUT CON4 CON1 LINE OUT TO PC SPEAKER 15-18V DC OR 12V DC CON2 S T R IC1 SA605D 39pF 2.2nF VR1 A LED2 LED1 TUNING Table 1: Capacitor Codes 36  Silicon Chip Q2 PN100 VC3 22k IEC Code 470n 100n   47n   10n   2n2    470p   39p   22p   18p 1k 10nF RSSI case, REG1 is fitted to regulate the supply down to +12V, while a 2200mF capacitor is also fitted to provide the necessary filtering. The only part of the receiver which does not operate directly from the +12V line is IC1, which needs a supply of +6V. This is provided by REG2, a low-power 5V regulator arranged here to provide an output of +6V by means of the 300W/47W resistive divider across its output. LED1 is connected to the +12V sup- mF Code 0.47mF 0.1mF .047mF .01mF .0022mF       NA      NA   NA   NA 470nF 1 1.2 H RF GAIN Value 470nF 100nF 47nF 10nF 2.2nF 470pF 39pF 22pF 18pF 10 F 220k IC2 LM358 L3 50k LIN 1 47 470pF 100nF 10nF 22pF 2.2nF 39pF 6-30pF 1.5k 100nF + 1 VC2 68 H RFC2 5.5MHz 100nF 10nF 10nF + + 220 2.2k 18pF CF2 2x100nF 10k 47k 220k 100k 10nF L2 CF1 100nF 10nF 1k 1.8 H 100nF C02008 8 02 C 06108081T B18080160 100nF 820 1.5k 1k 5.5MHz 2.2nF 91k 2.2nF 300 78L05 100 22 F D S 10 F REG2 1k Q1 1.8k 2.2nF BF998 47nF + 10 2200 F 470 F K + 47 H RFC1 G2 G1 D1 10 F 110k 150k 360 2.2nF 47k 1k 330 F 4004 6-30pF 2.2nF VC1 18pF A CON3 A 10 F Tap L1 IC3 LM386 1.8 H A REG1 7812 EIA Code 474 104 473 103 222 470   39   22   18 POWER VR2 50k LOG AUDIO GAIN ply via a 2.2kW series resistor to provide power indication, while diode D1 is in series with the DC input to protect against reverse-polarity damage. Construction As you can see from the photos, all of the receiver’s parts are mounted on a small double-sided PC board measuring 117 x 102mm and coded 06108081. The board has platedthrough holes incidentally, to ensure good connections between the copper on each side – especially in the area of IC1, where a sound earth plane is essential for stability. All the input-output connectors are mounted along the rear edge of the board, while the controls and two indicator LEDs are mounted along the front edge. Note that tuning capacitor VC3 (a standard “mini” tuning gang with only one section used) is mounted upside down on the top of the board, with its edgewise tuning knob fitted under the board. Two 3mm nuts are used as standoffs between the capacitor body and the Fig.2: install the parts on the PC board as shown on this overlay diagram and the accompanying photo. Make sure that all polarised parts are correctly orientated. top of the board, to bring the knob up closer to the board. This is important if you want to fit the receiver into a low profile instrument case, because the knob will otherwise interfere with the bottom of the case. All the components mount on the top of the board, including IC1 and Q1 which are both surface-mount devices or “SMDs”. Although you need to be especially careful when fitting IC1 and Q1, building the receiver should be quite straightforward if you work carefully and use the board overlay diagram (Fig.2) and the photos as a guide. Here is the suggested order of assembly: (1) Fit connectors CON1-CON4 along the rear of the board. (2) Fit all of the resistors, taking care to fit the correct values in each position. (3) Fit the 8-pin socket for IC2, orientating it as shown to guide you in plugging in the IC later. Note that a socket is not used for IC3, as the LM386N is more stable when soldered directly into the board. siliconchip.com.au What Is Radio Jove? Radio Jove is a radio astronomy education project sponsored by NASA – the US Government’s National Aeronautics and Space Administration. Other organisations involved in the project are the University of Florida’s Department of Astrophysics, the University of Hawaii, Kochi National College of Technology, the INSPIRE Project and companies such as Raytheon, RF Associates and Radio-Sky Publishing. The goal of Radio Jove is to promote science education by observing and analysing radio signals emanating from the planet Jupiter, the Sun and our Milky Way galaxy. The project is directed primarily at high-school science classes, both in the USA and internationally, but interested hobbyists and radio amateurs are welcome to participate. The Radio Jove project has an office at NASA’s Goddard Space Flight Center and also has its own website at http://radiojove.gsfc.nasa.gov/ On this site there are a wide range of resources and reference materials, including observing guides and links to useful secondary sites. Radio Jove also sells kits for a simple radio receiver suitable for reception of “decametric” noise signals from Jupiter or the Sun, around 20.1MHz (14.915m). The kits cost US$155.00 each plus shipping (from Greenbelt in Maryland). An assembly manual for the receiver can be downloaded from the Radio Jove website, for those interested. (4) Now fit IC1 and Q1 to the board, taking the usual precautions with these SMDs. Use an earthed soldering iron with a fine chisel-shaped tip (very clean) and hold each device in position with a wooden toothpick or similar while you apply a tiny drop of solder (tack solder) to the diagonal end pins of the device, to hold it in position while you solder all of the remaining pins. The idea is to make each joint quickly and carefully, using a bare minimum of solder so you don’t accidentally bridge between adjoining pins. Also make sure you orientate Q1 correctly; this 4-pin device is very tiny but its source (S) pin is wider than the other three. Orientate the device so that this pin is at lower left, and tack-solder this pin first if possible. (5) Next fit trimmer capacitors VC1 and VC2, making sure their flat sides face the centre of the board. (6) After these, fit all the smaller fixed capacitors. These are not polarised Table 2: Resistor Colour Codes o o o o o o o o o o o o o o o o o o o o siliconchip.com.au No. 2 1 1 1 1 2 1 1 1 1 2 5 1 1 1 1 1 1 1 Value 220kW 150kW 110kW 100kW 91kW 47kW 22kW 10kW 2.2kW 1.8kW 1.5kW 1kW 820W 360W 300W 220W 100W 47W 10W 4-Band Code (1%) red red yellow brown brown green yellow brown brown brown yellow brown brown black yellow brown white brown orange brown yellow violet orange brown red red orange brown brown black orange brown red red red brown brown grey red brown brown green red brown brown black red brown grey red brown brown orange blue brown brown orange black brown brown red red brown brown brown black brown brown yellow violet black brown brown black black brown 5-Band Code (1%) red red black orange brown brown green black orange brown brown brown black orange brown brown black black orange brown white brown black red brown yellow violet black red brown red red black red brown brown black black red brown red red black brown brown brown grey black brown brown brown green black brown brown brown black black brown brown grey red black black brown orange blue black black brown orange black black black brown red red black black brown brown black black black brown yellow violet black gold brown brown black black gold brown August 2008  37 L1 16T L2 20T TAP 4T L3 A B 15T A B A B 1. BEFORE WINDING EACH COIL, REMOVE ENAMEL FROM END OF WIRE (5mm). THEN TIN AND WRAP IT AROUND TOP OF ONE PIN (A) ON UNDERSIDE OF FORMER. THEN SOLDER. 2. THEN WIND WIRE TIGHTLY AROUND FORMER FROM BOTTOM, WITH TURNS CLOSELY WOUND. 3. WITH L1, WIND 4 TURNS THEN LOOP OUT AND TWIST AS SHOWN TO MAKE 'TAP'. THEN WIND REMAINING TURNS. 4. WHEN ALL TURNS HAVE BEEN WOUND, CUT WIRE ABOUT 13mm FROM END OF LAST TURN. THEN REMOVE ENAMEL FROM LAST 5mm OF WIRE, TIN AND BRING DOWN TO WRAP AROUND TOP OF SECOND PIN (B) ON UNDERSIDE OF FORMER. THEN SOLDER. 5. REMOVE ENAMEL FROM OUTER END OF L1'S TWISTED LOOP 'TAP', THEN TIN SO IT CAN BE SOLDERED TO PAD ON PC BOARD WHEN COIL IS FITTED TO BOARD. Fig.3: follow these instructions to wind coils L1-L3. 15 x 7mm RECTANGLE OF COPPER FOIL OR TINPLATE ON TOP OF IC1 WIRES SOLDERED IN EARTH VIAS NEAR PIN 1 END OF IC1 1 SHIELDING PLATE FOR IC1 14 x 10mm RECTANGLE OF COPPER FOIL OR TINPLATE OVER CENTRE LINE OF Q1 S WIRES SOLDERED TO VIAS IN Q1 SOURCE COPPER, AT EACH END OF Q1 VERTICAL SHIELDING PLATE FOR Q1 Fig.4: here’s how to make and fit the shield plates for IC1 and Q1. apart from the 22mF tantalum capacitor which fits between the 1kW and 91kW resistors, just to the right of IC1. This capacitor is polarised, so make sure its positive lead is towards the front of the board. (7) Now fit the remaining electrolytic capacitors, which are again all polarised. The correct orientation of each electrolytic capacitor is shown clearly in the overlay diagram. 38  Silicon Chip These two photos show the shield plates for IC1 (above) and transistor Q1 (right). You can make the shield plates from either copper or tinplate. (8) Next fit RF chokes RFC1 and RFC2, which should both be about 2mm above the PC board. (9) Now fit the two ceramic filters CF1 and CF2, which are not polarised. (10) Follow these with transistor Q2, diode D1, REG2 and LED1 & LED2. Note that the green LED is used for LED1 and the red LED for LED2. LED1 is fitted first, with its leads bent down by 90° about 8mm from the body. It’s mounted with its body 6mm above the board surface. LED2 is then fitted with its leads bent down about 14mm from the body and so that it sits about 14mm above the PC board. (11) Fit REG1, if you are using it, noting that it is mounted on a small 6093B type heatsink. The regulator leads are bent down at 90° 6mm away from the device itself, so they can pass down through the matching board holes. Then the device and its heatsink are fastened to the board using an M3 x 6mm screw and nut, after which the leads are soldered to the pads under the board. (12) Fit IC3 directly on the board, orientating it carefully as shown in the overlay diagram. (13) Next, fit tuning capacitor VC3. As noted earlier, this fits upside down on the top of the board at centre front, with M3 nuts used as standoffs. The capacitor’s tuning knob must be removed from the spindle before it is mounted and only refitted once the capacitor’s leads have been soldered under the board. (14) Fit VR1 and VR2 (the RF and audio gain control pots). These first have their spindles cut to 10mm long and any burrs removed with a small file. Then each pot is fitted to the board, making sure that you fit the linear (B50k) pot in the VR1 position, and the log (A50k) pot in the VR2 position. Pass their pins carefully through the board holes as far as they’ll go comfortably (ie, without undue strain) and then solder them to the pads underneath. Then you can fit the control knobs to the pot spindles. (15) Wind the three tuning coils L1L3. As you can see from the data box in Fig.1, all three coils are wound on 3mm diameter mini coil formers (Jaycar LF-1227), using 0.25mm enamelled copper wire. In each case, the coils are close-wound at the bottom of the former, as shown in the small diagram of Fig.3. Oscillator coil L3 has 15 turns, while the other two have 20 turns each. The difference between L1 and L2 is that L1 has a “tap” four turns from the bottom. This tap is formed from a loop of the winding wire, twisted and tinned at the end so that it can be soldered to the appropriate pad on the PC board (just below CON1) when the coil is fitted. It’s a good idea to apply a small amount of clear nail varnish to the upper part of each coil, to hold it in place. (16) When the three coils are completed, they can be fitted to the board. When doing so, make sure you orientate each coil so that its “A” pin (connected to the bottom of the coil) mates with the earthy or “colder” pad on the board. The board overlay diagram has a small “A” next to each coil, to guide you in this regard. (17) Next, you need to make a couple of copper shield plates for IC1 and transistor Q1 to ensure stability. Fig.4 and the photos show how these plates are made and fitted (note: if you are unable to obtain copper foil, you can use tinplate or blank PC board). Both shields are attached using short pieces of tinned copper wire which go into adjacent holes in the PC board. (18) Finally, plug IC2 (LM358) into its socket, with its notched end nearer IC1. siliconchip.com.au The PC board fits inside a standard plastic case measuring 140 x 110 x 35mm. Note how the two LEDs are bent forwards, to go through their holes in the front panel. Your Jupiter Receiver board should now be complete and ready for switchon and set-up. Set-up Before applying DC power to the board via CON4, turn both VR1 and VR2 to their fully anticlockwise position. Then plug a small loudspeaker (8W) or a pair of stereo headphones into CON3, so you’ll be able to monitor the receiver’s operation audibly. When you then apply power, very little should happen initially apart from LED1 beginning to glow. If LED1 doesn’t light, odds are that you’ve connected the DC supply to the board with the polarity reversed. Now try turning VR2 clockwise slowly. You should begin to hear a gentle hissing sound in the speaker or one of the ’phones. If you have a DMM (digital multimeter), measure the voltage at pin 8 of IC2. It should measure very close to +12V if you’re using REG1, or +11.4V if you are powering the receiver from a 12V battery. Now measure the voltage at the rear end of RFC2 (ie, the end nearer REG2) which should be very close to +6V. siliconchip.com.au Finally, measure the voltage at pin 1 of IC2; this should be quite low – a few tens of millivolts. If you then turn VR1 clockwise, this voltage should steadily rise due to noise being amplified by Q1, as its gain is increased. The hissing sound in the speaker or ’phone should increase at the same time. If all is well so far, your receiver is very likely to be working as it should and you’ll be ready for setting it up. This mainly involves adjusting trimmer capacitors VC1 and VC2 so that the input and output circuits of the RF stage are tuned to around 21MHz. The easiest way to do this is if you have access to an RF oscillator or signal generator, able to deliver an amplitude modulated RF signal of 21MHz to the receiver’s input. The generator’s output is set to a level of about 100mV at first. Then you should turn up both VR1 and VR2 to about the centre of their ranges (‘12 o’clock’), after which you can slowly turn the knob of tuning capacitor VC3 up from its lowest setting, until you hear a 400Hz or 1kHz tone (the generator’s modulation signal). Now fine-tune VC3 carefully back and forth with your thumb, to achieve the loudest signal. If the sound becomes too loud or LED2 (the RSSI indicator) begins glowing, turn down VR2 and/or VR1 to reduce the gain. And if the signal is still too loud, try reducing the output level from the RF generator. Once you are sure that the oscillator is correctly tuned for reception at 21MHz, the next step is to carefully adjust trimmer VC2 with a small alignment tool, to again find the correct position for maximum signal. You may again need to reduce the generator’s output level, to prevent overload when you do achieve a peak. Once the correct tuning position for VC2 has been found, the last step is to adjust VC1 in the same way. In this case, you will almost certainly have to reduce the output level from the generator to prevent overload. In fact, by the time the tuning procedure is finished, the generator’s output should be wound down to a mere 1mV or so. No RF generator If you don’t have access to an RF August 2008  39 The antenna should be suspended as high as possible above the ground with a north-south orientation. This can be done by taping it to Nylon clothesline rope and running this between two high fixing points (eg, between a house gable and a mast). The balun and its connections are made waterproof by housing it in a UB5 jiffy box – see inset. generator, you’ll have to delay this tuning operation until you have built the receiver’s antenna, erected it outside in a suitable position and connected it to the receiver’s input so that it can provide you with some sort of signal – either a short-wave broadcasting station somewhere in the 20.25-22.5MHz range or just some atmospheric noise. More about this shortly, after we’ve talked about antennas. Antennas for 21MHz For reception of noise burst signals from Jupiter or the Sun in the northern hemisphere, the Radio Jove people recommend the use of a twin-dipole antenna array in which two halfwave dipoles are each aligned in an east-west direction and spaced about one half-wave apart, with them both suspended at least 3.6m above ground. The outputs of the two dipoles are combined using a phasing cable arrangement, to tilt the antenna’s main receiving lobe towards the south – because currently, Jupiter’s orbit is inclined somewhat south of the equator. In fact, the “declination” of its highest point (“transit”) in moving over the sky is about -20° in the Northern sky (ie, quite low towards the south). 6960mm 35mm OD x 13mm thick L15 toroid ONE END OF SECONDARY CONNECTED TO CENTRE CONDUCTOR OF COAX, OTHER END TO SHIELD BRAID (COAXIAL DOWNLEAD TO RECEIVER) CENTRE OF ANTENNA WIRE LOOPED THROUGH TOROID 6 TIMES, TO FORM PRIMARY OF BALUN. SIX LOOPS OF SAME WIRE PASSED THROUGH TOROID TO FORM SECONDARY WINDING. FOR BEST RESULTS SUSPEND ANTENNA AS HIGH AS POSSIBLE (>3.6m ABOVE GROUND), AWAY FROM METAL OBJECTS AND WITH A ROUGHLY NORTH-SOUTH ORIENTATION. Fig.5: this simple single-dipole antenna can be used with the Jupiter Receiver to receive Jupiter’s noise bursts. The dipole is cut to a length of 6960mm to make it resonant at close to 21MHz and is coupled to a coaxial downlead using a simple 1:1 balun made from a ferrite toroid. 40  Silicon Chip In the southern hemisphere, Jupiter’s orbit is currently much higher in the sky. In Sydney at the time of writing, the declination of its transit point is only slightly north of directly overhead and it’s predicted to take a couple of years before it swings significantly north. That’s because the cyclic period of Jupiter’s declination is almost 12 years and its southerly peak was earlier this year. All this means that for the next couple of years, in Australia and New Zealand it should be quite feasible to use a basic single-dipole antenna for reception of Jupiter’s noise bursts. Accordingly, we have produced and tested the very simple antenna design shown in Fig.5. It consists of a single length of multi-strand copper wire (we used one side of a length of figure-8 speaker cable), cut to a length of 6960mm (6.96 metres) to make it resonant at very close to 21MHz. This antenna should be suspended at least 3.6m above the ground and aligned as closely as possible to a north-south direction. I did this by taping it to a 6m length of Nylon clothesline rope, which was then run between a high point on the gable of my house and the top of a 3m mast, attached to the side of a workshop in the backyard. To couple signals from the antenna siliconchip.com.au to a cable running back to the receiver’s input, I made up a 1:1 balun (balanced to unbalanced transformer) using a small ferrite toroid as shown. This toroid uses L15 material and is 35mm in outside diameter, with a thickness of 13mm (Jaycar LO-1238 or similar). The centre of the antenna wire itself is looped through the toroid six times to form the primary winding of the balun, while a short length of the same type of wire is also looped through the toroid six times to form the secondary winding. To make the balun weatherproof and secure, I housed it in a little UB5 jiffy box (83 x 54 x 31mm), with the two ends of the antenna wire brought out through a 3mm hole on each side near the top. A BNC socket was then fitted to the lower end of the box, with the ends of the balun secondary winding connected to the socket inside. The downlead cable was connected to the socket on the outside, after the box lid had been screwed on. The whole thing was then hauled up on the Nylon rope, as it’s very light in weight. I used short strips of gaffer tape to attach the antenna wire and balun to the rope but Nylon cable ties would also be suitable. No-generator tune-up As mentioned earlier, if you don’t have access to an RF oscillator or signal generator it’s still possible to tune up the receiver reasonably well once you have an antenna to provide it with some signals in the vicinity of 21MHz. The way to do this is to connect the antenna, apply power to the receiver and set both VR1 and VR2 to their midrange (12 o’clock) positions, so you can hear a reasonable level of noise. Now try adjusting tuning control VC3 very slowly, to see if you can find a shortwave broadcasting station. I found a Chinese station at about 21.68MHz, for example – about twothirds of the way up the tuning range. If you do find a station, leave VC3 set to the position for clearest reception and then try adjusting trimmer VC2 very slowly and carefully with a small alignment tool. You should find a position which gives a peak in the signal’s reception but you may need to turn down gain controls VR2 and/or VR1 to lower the volume and prevent overload, so you can accurately find this peak. Once you are confident that VC2 siliconchip.com.au Decametric Radio Astronomy B ACK IN 1955, US radio astronomers Bernard Burke and Kenneth Franklin discovered that the planet Jupiter was a strong source of “noise burst” radio signals in the frequency range between about 8MHz and 40MHz – where the radio wavelength is in the tens of metres (hence the term “decametric”). They were using a “Mills Cross” antenna array, by the way, the design of which had been pioneered by Australian radio astronomer Bernard Mills of CSIRO’s Division of Radiophysics. The first Mills Cross had been built at Fleurs (about 40km west-south-west of Sydney) the previous year. It was soon discovered that the Sun itself is also a source of noise bursts during periods of sunspot activity and “coronal mass ejections” (CMEs). These solar noise bursts extend from the decametric range up to around 80MHz. The relative ease of receiving noise bursts from Jupiter and the Sun in the decametric frequency range using low-cost equipment seems to be why the Radio Jove project selected this range (rather than in the UHF or microwave regions). It should be noted though that because the signals are broadband in nature, the specific frequency used to receive the signals is not critical. The main requirement is to avoid frequencies occupied by international broadcasters and other terrestrial sources of radio signals. Useful websites A great deal of useful information on Jovian and Solar decametric radio astronomy – both theory and practice – can be found on the following websites: http://radiojove.gsfc.nasa.gov/ http://ufro1.astro.ufl.edu/dec-contents.htm http://www.jupiterradio.com/ http://www.radiosky.com/ The last of these sites is the source of the Radio-Skypipe software, which runs on a Windows PC and allows you to record noise data from a Radio Jove or similar receiver and print out “chart recordings” of them. There is a freeware version of the software which can be downloaded from this site. A useful source of skycharts and information on the rising and setting times for Jupiter (as well as many other astronomical bodies) in any specific location is: http://www.heavens-above.com/ An Australian site with useful information on solar storms and their effect on terrestrial radio conditions, etc is: http://www.ips.gov.au/ has been set correctly, leave both VC2 and VC3 with their current settings and turn your attention to VC1, the input circuit trimmer. Again it’s a matter of adjusting this very slowly and carefully until you achieve a signal peak, turning down VR2 and VR1 if necessary to prevent overload and distortion. What if you can’t find a shortwave station to help in this tuning-up procedure? That needn’t be a complete disaster, because if you have a DMM it’s possible to use a similar procedure using just the decametric “cosmic noise” being picked up by the antenna. To do the tuning up this way, set your DMM to a low DC voltage range (say 0-2V) and connect it to the re- ceiver to monitor the voltage at pin 1 of IC2. Then set tuning capacitor VC3 to the centre of its range and gain pots VR1 & VR2 to the centre of their ranges as well. When you apply power to the receiver, you should get a reading of 100-200mV or so on the DMM, as well as hearing the received noise in the speaker or ’phone. Now try adjusting VC2 slowly, first in one direction and then the other, to see if you can increase the DMM reading. Keep turning slowly in that direction, until the meter reading reaches a peak and then begins to drop again. Then return to the position where the reading peaks and leave VC2 in that position. If the DMM reading rises above about August 2008  41 There are just three controls on the front panel: an RF gain control, a tuning thumbwheel and an audio gain control. The RSSI (received signal strength indicator) LED lights when there is a signal overload (see text). 800mV, lower the RF gain by turning potentiometer VR1 anticlockwise, to bring the reading down again to 200mV. This will make it easier to see the peak reading on the DMM as you adjust variable capacitor VC2. After VC2 has been set to produce a peak in this way, leave it as before and follow the same procedure with VC1. Again turn down VR1 if necessary to prevent the DMM reading from rising above about 800mV. Once VC2 and VC1 have been set, your Radio Jupiter receiver should be tuned up about as well as possible without access to a generator. Fitting it to a case The PC board is designed to fit inside a low-profile plastic instrument case measuring 140 x 110 x 35mm. First, you will have to drill holes in the front and rear panels. Figs.9 & 10 show the front and rear panel artworks and these can be downloaded from our website, printed out and used as drilling templates. The board is secured to the two corner pillars at the back of the case using self-tapping screws, while the front of the board is secured to the front panel via the pot shafts and their nuts. Note that the board sits slightly proud of the front pillars in the case. Don’t attempt to screw the board down to these pillars (otherwise the board could crack). Testing with Radio-Skypipe To try out the new receiver and the Chart Started 11 June 08 by Jim Rowe in Sydney, Australia Fig.6: this recording chart covers almost the full period (about 11 hours) of Jupiter’s pass on the night of June 11, 2008 but shows very little evidence of signal bursts from Jupiter. Things were quiet around Jupiter that night! 42  Silicon Chip siliconchip.com.au siliconchip.com.au www.siliconchip.com.au 15-18V DC (OR 12V DC) ANTENNA SILICON CHIP LINE OUT TO PC SPEAKER TUNING POWER POWER RSSI RF GAIN also able to print it out as a pseudostrip chart recording – see Fig.6. As you can see, the recording covers almost the full period of Jupiter’s pass that night (June 11, 2008), because it rose at about 7pm, reached full transit at 2:07am and set again at around 9am the next morning. But the sky was very overcast that night, so perhaps that’s why there’s very little evidence of any bursts of signal from Jupiter. Either that, or things were pretty quiet around Jupiter that night. Looking around for some more information, I discovered that there are two different kinds of decametric noise burst from Jupiter: “L” or long bursts and “S” or short bursts. Both seem to be controlled by various factors, including which side of Jupiter is facing our way at the time and also the orbital position of Jupiter’s principal moon, Io. Sunspot and storm activity on the Sun also seem to play a role. They affect the way the Sun sends out streams of charged particles which can spiral RADIO JUPITER basic home-brew dipole antenna described above, I decided to download a copy of the “Radio-Skypipe” software which is recommended by the Radio Jove people. This is a data-logging application which runs under Windows 95/98/NT/2000/XP and can be configured to log data signals via either the ADC (analog-to-digital converter) in a standard 16-bit PC sound card or an external ADC. There’s a free-download version for non-commercial and non-government users and a Pro Edition with extra bells and whistles available for US$39.95, for commercial and serious users. I had no trouble installing the RadioSkypipe software on my old Win98 workshop PC and I was soon using it to take samples of the Jupiter Receiver’s audio signal twice every second. I then left it running so that it would log a complete pass of Jupiter over the following night. When I stopped the logging at 7.00am the next morning, I then saved the log file to the hard disk and was SILICON CHIP Fig.8 (left): the RadioSkypipe software has lots of logging options, including start and logging duration times. AUDIO GAIN Fig.7 (above): this screen grab from the Radio-Skypipe software shows a recording chart of the 21MHz signal for a 10-minute period. Fig.9: these artworks can be used as drilling templates for the case panels. around in Jupiter’s magnetic field. So it seems that there probably wasn’t much happening around Jupiter the night of my first logging run. The only way to find out is to keep trying, I guess. How about giving it a SC go yourself? August 2008  43 SERVICEMAN'S LOG She was just what I’d always fancied Occasionally, when I am allowed out by myself, I wander off to the auctions for the day. I always enjoy the experience but I have learnt that what you might gain is at the expense of a day’s lost wages and if you do buy something, it’s often a pig in a poke with no guarantees. I’ve got to admit that I buy a lot of stuff at auctions. But you can never have enough stuff and so there I was recently at another auction, recklessly bidding for all sorts of ex-government/ ex-university electronic gizmos I didn’t really need. And that was when I spied her. She was gorgeous and just what I had always fancied. Now before you all get too excited, “she” was in fact a Gould Classic 6000 4-Channel 200MHz True Trace Digital Storage Oscilloscope with an LCD readout. It looked in good order apart from two gouges on the edges of the front escutcheon where it may have been dropped and I was advised it didn’t work. That didn’t worry me too much as it would reflect in the price which it indeed did and I was a very happy bidder when I walked out with my prize for only $100! Subsequently, I found out that these units were made in Ilford, Essex in the UK about 12 years ago (my old stomping ground) and at the time sold for about $5000 plus. When I got it back to the workshop, I found that the 2A mains fuse had blown and a replacement also did the same immediately. Oh well, she was never going to be that easy! Opening the case revealed what looked like a full-blown computer and a large complicated power supply unit which I removed. Obviously, I didn’t have a circuit diagram but I figured that this must be similar to an ordinary computer power supply. I carefully measured all the components in the primary circuit but 44  Silicon Chip couldn’t initially find much wrong. There were no obvious short circuits and the only components I could possibly find a slight problem with were TR1 & TR5 (MJE13009), C10 & C11 (100mF 63V), R4 & R5 (22kW 1W) and the MOV1 & MOV2 varistors across the two main electrolytic capacitors (C1 & C2, 680mF 200V). These VDRs were marked 20N241KJVRXHT and are not easy to source. I also noted a 3300mF 10V electrolytic capacitor in the secondary with a domed top, so this too would require replacement. I tried tracing out the circuit diagram of this part of the power supply but it required removing a lot of components in order to trace the tracks of the double-sided PC board. Anyway, I replaced all the above suspect parts with the best equivalents I could find but found that the main electros (C1 & C2) were now getting hot and the fuse kept blowing. After further investigation, I removed T3’s FL black lead that was stretched tightly across transformer T4. And when I did so, T4 fell out, severing its remaining leads to the PC board. I now realised what had happened. The oscilloscope had indeed been dropped and transformer T4 (Part No. JK9501-01) had broken one of its primary winding legs. Well, now that I knew what was wrong I thought it would be a piece of cake to get the parts. Initially, I tried all the usual wholesalers like WES Components, Farnell and RS Components, etc without success, so I Items Covered This Month • • • • • • • Gould Classic 6000 4-channel 200MHz True Trace Digital Storage Oscilloscope Sony STRDA50ES 120W tuner-amplifier Hitachi PMA-300 plasma TV PanaSound A51 5-channel amplifier NEC FS-68V81F TV set JVC VMZ50DX4 127cm plasma TV Holden Vectra went to the Internet and tried to track down the English manufacturer. I then discovered that Gould was now part of a number of EU conglomerates (Gould Nicolet, Nicolet and LDS Groups) around the world. I emailed all of them but did not get a single reply. While I was trying to work out what to do next, I accidently found a label on the opposite end of the power supply which said that it was made by a third party, Ferrus Power of Peterborough UK, and that the model number of the power supply was FP250-510/1. This English company is also part of another group of companies but their website advises that they do not sell spare parts, nor do they provide circuits. I emailed them and although they can service the power supply, it would cost me more than $400 by the time freight was factored in. I will now devote my energies to converting a Chinese-built computer power supply. If you can’t scrounge one, these are available new at almost give-away prices. This oscilloscope only requires ±5.2V <at> 6A, ±12V <at> 3A and 22V at 2A. Hardly a big deal. Sony tuner-amplifier A 1998 Sony STRDA50ES 120W tuner amplifier was brought in DOA (dead on arrival). First, I removed siliconchip.com.au the covers and checked at least five cartridge fuses but all were intact. I then applied power but there were no lights and no clicking relays – in fact, absolutely no signs of life. Looking in on the top righthand side, there is a small power board with a relay on it which then feeds another larger power supply board (PS) beneath it. The problem looked to be on the lower board but the access wasn’t straightforward. First, I had to remove the upper board, some covers and loosen the back panel before I could access the six screws that hold this PS board. I then had to unplug all the leads that go into it before lifting it up towards the front and pulling it out vertically. It was so tight that the board had to be flexed quite bit, so much so that a small piece broke off at the back. When I examined the board, I found that it was cracked in a number of places, possibly due to it being flexed during removal. As a result, I resoldered all the copper tracks as necessary and repaired any cracks in the fibreglass using superglue. Apart from that, I could find no other problems with it. Having completed these repairs, I reinstalled it very carefully and reconnected all the plugs and sockets. I then checked it over carefully and reapplied power and it burst into life. So fixing the cracks repaired the fault which meant I wasn’t responsible for the cracks (at least not for all of them). But how did this come about? Well, my theory is that either someone else removed the board before me siliconchip.com.au (and damaged it) or the set had been dropped. But if it had been dropped, why did this board crack while all the other boards were undamaged? The only clue I have is that the top lid on the lefthand side has a dent in it. Perhaps the PS board is held in so tightly by its six screws that a heavy drop can cause the metalwork to temporarily distort and crack the board. Digital tuners Recently, we have been having fun and games with digital tuners. One was in a Toshiba TV set whose picture was pixellating on UHF Channels 9 and 90. By contrast, analog reception on this set was perfect on all channels. The problem was due to the automatic scan that picked up and stored four Channel 9s – UHF Ch9, UHF Ch90, VHF Ch9 and VHF Ch90. However, it puts in the UHF stations first (ie, ahead of the VHF stations) and it was the UHF channels that were pixellating. You can fix this by selecting the best stations and making them favourites but it is a nuisance. One way is to disconnect the aerial for the first half of the scan (ie, while it scans the UHF channels) and then replace it for the second part (ie, for the VHF channel scan). The set will then only tune in the VHF stations and skip the UHF channels. There has also been a tuning problem with JVC digital tuners which, fortunately, is easily fixed. Actually, the problem isn’t just confined to JVC but to several other brands manufactured by the same factory in China as well. To tune in, you select the Quick Search Menu and then the location (eg, NSW). The tuner then starts scanning August 2008  45 Serviceman’s Log – continued a design fault or one that happened with normal wear and tear. Either the unit had been struck by lightning or more likely, the client had plugged something pretty dangerous into a line input to cause such a major failure. Unfortunately, due to lack of evidence, the manufacturer had to wear the cost of this gross neglect. The dealer was annoyed too because he had to swap the unit over when the part had to be ordered, so as not to inconvenience the idiot customer. Talking of idiots for stations but may come back with the message “Cannot Find Stations”. We changed the Digital Tuner Board (DTU) which sometimes fixed the problem temporarily but it wasn’t until we got five returns from Victoria that we worked out what was happening. Initially, we traced the problem to the EEPROM but it wasn’t until we reset it every time before searching for stations that we realised there was no automatic overwriting facility for stored channels. So if the unit had been tuned into Victorian channels, for example, there was insufficient space left to tune in NSW stations. Hopefully, the manufacturers will fix this soon. In the meantime, you have to do a full factory reset from the menu each time before rescanning. Hitachi PMA-300 plasma An Hitachi PMA-300 plasma set came in with a vertical green venetian blind affect on the lefthand half of the screen. Initially, we thought it was the control panel but in fact, it was the y-drive upper and lower boards that were short circuit on the output (pins 7-14).These measured 0.4W instead of 1.8MW. These boards are cheaper to buy from LG, who actually make them. 46  Silicon Chip In the course of all this, the picture decided to fail and a “y-sus” kit consisting of three boards from LG had to be installed as well. ParraSound 5-ch amplifier We had a ParraSound 5-channel Amplifier A51 come in under warranty from a dealer. The set would not turn on but it wasn’t the on/off switch that was at fault, as some people think when a set won’t start. This set has a complex protection circuit involving no less than five relays. The unit is packed with electronic circuitry and the main power supply unit is mounted underneath which make access difficult. After a lot of intemperate language, I found that a +15V rail was missing due to a burnt out 15V IC regulator on this bottom board. This was replaced and the board reinstalled but when the unit was switched on, it immediately started to cook again. Obviously, there was a short somewhere on the +15V rail and this turned out to be on the input preamp board. In fact, there were dead shorts on the three control ICs mounted on it. A new board was ordered and fitted, which fixed the fault. It was fairly obvious this was not Talking of idiots, I was called out to a supposedly dead NEC FS-68V81F TV set. When I arrived, I could see that the set was in standby with the red LED on. I asked for the set’s remote control and was first passed the video’s remote followed by the Foxtel remote. While he was looking for the original TV remote control he swore blind he never used, I pushed the front control buttons on the front of the set. One of them switched the set on, much to my client’s disbelief and my annoyance. He had been using the master on/off switch only and was then using the remotes to select the source of entertainment he wanted. A power cut or surge had meant that the set had switched to Standby and so using the master switch only made no difference. Like most modern TVs, this set uses an on/off system that remembers how it was last switched off. So if it is switched off in Standby mode, it will come back on in Standby. Similarly, if it is switched off when fully on, it will switch back on fully on. This sequence had been broken at one stage – it was just a matter of switching it on again. It’s all in the instruction book and is dead simple if you have the remote. And yes, I had asked him about all this over the phone before I called. The PC & the plasma TV I was recently called out to a bowling club that wanted to connect a computer to their plasma TV. Apparently, they had connected it correctly but were getting nothing. I arrived to find that the TV was a Panasonic TH50 PX600A Viera plasma set which had been connected via 15pin VGA socket to an Acer notebook. I found that the notebook PC had to be told to use an external display by siliconchip.com.au pressing the Function plus F5 keys, so that both the internal and external displays could be used together. This then gave a distorted image on the plasma set but after going into the TV PC Setup menu and setting it for WXGA and Horizontal and Vertical Sync, I got a perfect picture. Back at the computer I messed with the resolution and set it to 1024 x 768 resolution and 32-bit colour. I was a bit confused with the choice of multiple monitors but an Intel 830M Graphics was the driver chosen. This gave an excellent picture so I chose to leave well alone (if you set the resolution too high, you can often lose the picture). JVC VMZ50DX4 plasma TV We had a JVC VMZ50DX4 127cm plasma (also made by LG) come into the workshop with its accompanying Multi Media Box. This set would start to turn on but then turn off again. A few quick voltage checks showed that neither the 65V rail nor the 180V rail were coming out of the power supply unit to feed the y-sus board. Disconnecting this board restored these supply rails but the real cause of the problem turned out to be a short on the z-sus board which plugs directly into the y-sus board. The z-sus board is actually quite a bit cheaper from LG ($233 + GST) than it is from JVC but we could not match the exact part number. The z-sus board in the JVC was 6871QZH043B and the nearest LG part numbers were 6871QZH041B, 042B or 043B. However close examination of these boards showed the only difference to be one of the main electrolytic capacitors (C5) which wasn’t fitted. Instead, the other three in parallel are increased in value from 330mF to 680mF. In the end, we ordered the LG board and simply added the extra electrolytic capacitor from the faulty board, just in case! The set worked well after that. The faulty Vectra This story is about an electrical problem in a Holden Vectra and was sent in by D. S. from Howard in Queensland. Here’s how he tells it: I read the story about the Falcon XE electrical problems in the service- man’s section of the March 2008 issue with more then a little joviality. It reminded me of my days on the tools as an automotive electrician and one of the many tales of woe which arose from those everyday jobs which pay the bills. The vehicle was a 2001 Holden Vectra with pretty much every conceivable labour-saving device fitted. When turned on, the dashboard display has a small monitor-type display which informs of low fluid levels or inactive globes, etc and the instrument cluster also lights up with all the relevant warning lights. It’s quite a dazzling sight until the self-test routine is complete, at which point the displays dissolve into darkness and the everpresent economy readings. The initial fault was that the “SRS Airbag” warning light had illuminated and the SRS system had disabled. This is usually an easy fault to fix. Most problems are caused either by one of the accelerometers becoming detached (or damaged) or by the clock spring mechanism in the steering column. Plugging in the mandatory system scanner revealed a mixed hash of fault codes, none of which bore any direct relationship to the SRS systems! Maybe the SRS control module had suffered damage or had a logic fault? Subsequent testing revealed that this was not the case. As this stage, I then began getting other fault reports, like a brake-lamp globe not working. The traction control WE USE INNOVATIVE METHODS THAT ENABLE OUR CLIENTS TO ACCELERATE THE PRODUCTION OF PROTOTYPES AND UNIQUE PRODUCTS • • • • Rapid Prototyping 3D Cad Design Toolmaking Fused Deposition Modelling (FDM) 30 Paradise St, Banyo Queensland 4014 sales<at>3dprinting.com.au Ph: + 61 7 3267 8104 Fax: + 61 7 3267 8971 www.3dprinting.com.au siliconchip.com.au • • • • 24 Bit Colour 3 Dimensional Printing Direct Casting Moulds Investment Casting Patterns Flexible Elastomeric Printed Parts • • • • Snap Fit Parts Urethane Moulding Vacuum Metallising Superex REDUCE DEVELOPMENT COSTS AND ACCELERATE SPEED TO MARKET Australian Agent ZCorp 3D Printers The World’s Fastest AND Most Cost Effective Rapid Prototyping System August 2008  47 Serviceman’s Log – continued An auto-electrician’s lot – there’s lots of wiring in modern cars and tracking down a fault in this wiring can be a real nightmare. warning lamp also came on, although the traction control was not actually outputting any actual fault codes. Furthermore, a quick check of the brake lamps showed that they were working OK. The next fault to show was an ABS (anti-lock braking) fault. Now the ABS system is tied into both the SRS and traction control systems, so maybe we were now getting somewhere. Again, the control modules were tested and again no fault was found. The modules were all functioning perfectly. Next, I removed and tested each individual component and again, I found no faults. The wheel sensors were perfect and the accelerometers were correct and in calibration. The rear globes were even removed and their individual resistances checked! It was time to get tough. My next step was to start checking the wiring harness. Unfortunately though, this isn’t an easy job as the harness mostly sits inside the interior trim in it’s own recess and is secured using cable ties. The interior trim is also like a big jigsaw puzzle and you have to remove it in the correct order to prevent damage. For example, to remove the centre console, you first have to remove the trim around the radio, then unplug the wiring harness to the switches mounted in this trim, then unscrew 48  Silicon Chip and remove the radio. This then allows you to detach and remove the lower section of the radio console, giving access to the screws which hold the gear lever cover in place. Once you remove the gear lever covers, you can then remove the remaining screws and trim from the centre console, detach the wiring harness to the window switches and then remove the console! Once all this had all been done, it gave me access to one of the SRS modules and allowed me to check the wiring. However, on testing, I found that I had several conductors which were outputting my trace tones! This was promising and it was looking like there were shorted conductors. Another test on the harness behind the glove box gave the same symptoms. Locating the shorts Now all I had to do was locate the shorted cables in an enclosed wiring harness, with an average of 60 conductors in each harness section, Easy! Eventually, I did locate the damage to the wiring harness although it took a little time. However, getting the harness to a point were it could be repaired took a lot longer. The damage was located above the steering column, between the column cradle and the firewall. Getting at it required the removal of the entire dashboard, dashpad and instrument cluster, along with the steering column, etc. The accompanying photo shows the amount of disassembly required to gain access to this harness. The damage was caused by the loss of the protective wrapping between the harness and the metal of the column cradle and the firewall. The metal had rubbed through the cable insulation and caused shorts between various conductors and to ground (ie, to the vehicle’s body). Many of the wiring circuits must be protected by current limiting in the modules, as a short to ground on a supply circuit usually results in blown fuses and fireworks! Many damaged conductors did show signs of heat damage and carbonisation due to arcing and part of the harness which connected the dashboard diagnostic display to the body control module was badly burnt. However, the modules showed no signs of damage! A replacement harness would not have been any easier and would have been expensive, so I decided to repair the existing harness. That repair was completed in a couple of hours and the vehicle was reassembled and passed all its functional tests with flying colours! Luckily, none of the fibre-optic cables had suffered damage and neither had any of the shielded cables. When it comes to automotive electronics, we are always quick to blame the computers for any faults and issues. However, they are really very reliable and in this case, it was the cables that were at fault. Modern on-board diagnostics are also reliable but can cause confusion if not interpreted correctly. After all, diagnostic outputs are only accurate when the input signals are accurate and if those same signals become corrupted or mixed, so do the electronic control module diagnostics. The vehicle has now been performing flawlessly for several months without problems. However, this job serves as a reminder that not all faults are simple ones or are located in the electronic modules and that finding the problem and gaining access to it can sometimes take a lot more time then the actual repair. Some are caused by simple components like the wiring, which we all take for granted. Others are caused by even simpler components, like the owner or driver SC but that’s another story! siliconchip.com.au August 2008 NEW HEAVY DUTY TV WALL BRACKETS Capable of taking up to 80kg, these heavy-duty LCD or plasma TV brackets will save valuable floor space and keep your investment out of reach of mischievous fingers. Two types are available: • CW-2822 has a 30° range of tilt movement only • CW-2824 is able to tilt 30° & swivel left & right through 80° and extend up to 30cm away from the wall. Note: TV not included $ 89 95 $ Cat: CW-2822 149 95 Cat: CW-2824 LABORATORY MAGNIFIER LAMP This desktop magnifier lamp features a 100mm glass lens that will provide you with 3x magnification.The lamp has a solid base and a bright 12W energysaving fluorescent lamp. The lamp also features a swivel $ joint enabling you to 95 position the lens to Cat: QM-3529 suit your needs. FAST BATTERY CHARGER Recharge up to four AA or AAA Ni-Cd or Ni-MH batteries with this handy charger that utilises Delta V voltage detection to ensure maximum battery life. Integrated LCD status display. Charge on the go with the included car cigarette lighter cord or with the included mains plugpack. $ 95 • Charge time varies to battery's capacity. Cat: MB-3549 CW-2824 $ CW-2822 99 95 Cat: XC-0338 PURE SINE WAVE INVERTERS HIGH CURRENT MOTOR SPEED CONTROLLER KIT Ref: Silicon Chip Magazine March 2008 This kit will control a 12 or 24VDC motor at up to 40A continuous and features automatic soft-start, fast switch-off and a 4-digit display to show settings. From $199 180 WATT MI-5160 • Power surge 300W • Weighs 1kg • 240(L) x 119(W) x 60(D)mm $199.00 380 WATT MI-5162 • Power surge 650W • Weighs 1.1kg • 240(L)x119(W) x 60(D)mm $229.00 600 WATT MI-5164 • Power surge 1000W • Weighs 1.4kgs • 300(L) x 119(W) x 60(D)mm $349.00 Speed regulation is maintained even under heavy loads and the system includes an overload warning buzzer and a low battery alarm. • Kit contains PCB and all $ 95 specified electronic components. 79 Cat: KC-5465 STEREO VALVE AMPLIFIER 2 X 25WRMS 39 40W SOLDERING STATION STOCK Keep track of important weather parameters like wind speed and rainfall. It also has a calendar and a clock with alarm function. In addition, it measures indoor and outdoor temperature and humidity. • Wind speed in km/h or mph • Max min and rainfall history in mm or inches • Temperature in Celsius or Fahrenheit • Requires 2 x AA & 2 x AAA batteries • Display: 180(H) x 104(W) x 24(D)mm *Parts shown not to scale These inverters provide clean 230VAC power to run sensitive electronic equipment such as clocks, TVs, electronic scales, etc. from your car's battery. We have models suitable for running your laptop in the bush to powering a small microwave in a motor home. They have fan assisted cooling and electrical isolation for safety. 39 This temperature controlled station comes with a lightweight iron with anti-slip grip and tip cleaning sponge, with temperature adjustment up to 450°C. It also has a 4mm banana socket connected to mains earth for soldering static-sensitive components. NOW IN WIRELESS DIGITAL RAIN GAUGE WITH ANEMOMETER Most valve amps have ridiculously low power output, no tone controls, hum like a substation and cost ludicrous amounts of money. Not this one: it has 25WRMS per channel, tone controls, very low hum and distortion, sounds pretty damn good and costs no more than an equivalent solid state amp. • Valves: 2 x 6N1, 2 x 6P15 • Power output: 25WRMS per channel • Input sensitivity: 300mV • S/N ratio: >80dB • THD: <0.5% • 270(W) x 290(D) x 140()mm $ NEW STORE NOW OPEN IN LIVERPOOL, NSW. 299 Cat: AA-0474 6-IN-1 COMPACT $ 49 95 Cat: TS-1620 SCREWDRIVER This innovative screwdriver has six of the most useful blades. They are made of a vanadium and molybdenum alloy and store neatly in the handle. This may become one of the handiest tools in your kit. Supplied with the following $ 95 blades. • 128mm long • Slotted: 4, 5, 6mm • Phillips: #1, #2, #3 Cat: TD-2028 15 Free Call: 1800 022 888 for orders! www.jaycar.com.au 3/381 Macquarie St, 2170. Ph: (02) 9821 3100 Fax: (02) 9821 3188 1 AUTOMOTIVE PREVENT DRIVEWAY ACCIDENTS Advanced Car Alarm with Pin Code Function 2.4GHz Wireless Reversing Camera A full featured car alarm at a bargain price. It features code hopping remotes, a 2 stage shock sensor, microwave, door and boot trigger and a 125dB battery backup siren and much much more! It also has a valet parking or car wash feature that enables the system to remain disarmed, but the door and boot release will work normally. Simply splice the monitor and camera power lines into the car's reversing light cable and it will automatically switch on when you select reverse gear. Once activated the camera and monitor deliver a clear view of the area behind your car. • 2.4" wireless colour LCD screen • Colour CMOS camera • 110° Camera viewing angle $ Car Speakers This new improved range of full range car speakers feature injection moulded woofer cones and silk dome tweeters for smooth high-end response. The 3-way models have piezo mid-range drivers and all have grilles and crossovers included at a price that won't break the bank. See in-store or website for speaker measurements. 4" 2 Way • Power handling 55WRMS • Freq resp 100Hz - 20kHz Cat. CS-2385 $29.95 pr Response UnderSeat Active Subwoofer Has a wired remote control unit with mute and volume controls. Line level (RCA) inputs or speaker signal inputs. • 130mm polycone woofer • Power: 90W RMS • Frequency response: 80 - 200Hz • 288(L) x 200(W) x 69(H)mm • While Stocks Last - No Rainchecks Was $129.95 $5 6 x 9" 4 Way • Power handling 100WRMS • Freq resp 45Hz -20kHz Cat. CS-2388 $59.95 pr $ 109 95 Cat: CS-2273 $ 34 95 Cat: CS-2277 • See our Website for full specifications $ 2 Cat: BI-8207 Low Profile Subwoofer Their huge power handling and cone excursion make these the ideal subs for people who really want massive SPL in a compact package. Two models available. Nominal impedance 4 ohms 10" 250WRMS Cat. CS-2356 $79.95 ea 12" 350WRMS Cat. CS-2358 $99.95 ea From $ 79 95 This kit has all the electrical wire, speaker cables, connectors, screws and lugs required to install most systems and will support up to 100W. See in-store or website for list of included parts. Was $44.95 $10 $ 29 95 Cat: QP-2251 Car Noise Filters Car noise filters or hot line filters are used to reduce noise and interference entering your car stereo through the power lead. The car alternator is one of the most common sources of problems, and these essential devices can help to reduce this. Three sizes available depending on the power rating of the affected amplifier / radio etc. From $ AA-3072 AA-3076 AA-3081 13 AA-3072 For basic car stereos • 63 x 31mm • 5 Amp $13.00 AA-3076 For medium car stereos • 78 x 60 x 46mm • 20 Amp $22.50 AA-3081 Effective against 'engine hum' & 'ticking • 75 x 40 mm • 40 Amp $29.95 Audio Wiring Kit Installing A Sound System In Your Car 149 Cat: LA-9008 This handy test unit makes it so easy to measure current on individual circuits. Simply plugs into any standard blade type fuseholder and provides an easy-to-read LCD of the circuit's performance. • Measures up to 20A. $20 Literaly feel the bass! Works like a speaker, but instead of a cone it has a steel mass that transmits a jolt of energy to give an interactive feel to your home cinema or sound system. Use single or multiple units to give bass a new meaning. Was $39.95 6" 3 Way • Power handling 85WRMS • Freq resp 65Hz - 20kHz Cat. CS-2387 $49.95 pr $ Auto Current Tester Bass Shaker 4 Ohm 25WRMS 5" 2 Way • Power handling 70WRMS • Freq resp 80Hz -20kHz Cat. CS-2386 $39.95 pr 2 269 Cat: QC-3721 CAR AUDIO This essential book thoroughly covers all areas of installation including , but not limited to, amplifier configurations, speaker placement, second batteries, DC cable selection, cable resistance and speaker box venting. • A4 8 pages BONUS SPARE 9 REMOTE LA-900 VALUE $34.95 In-Dash Multimedia Player $ 34 95 Cat: AA-0440 3 Channel Video Distribution Amplifier for Cars This one-to-three video amplifier is ideal for automotive use and will let you share the video signal from your in-car video or DVD system with back seat passengers or other screens in the car. • Composite video input and output • One input to three outputs • Works with all in-car video screens • 12 volt powered • Female RCA I/O connectors • Dimensions: 63(L) x 32(W) x 30(H)mm Cat: QC-3436 • Lead length: 200mm $ 29 95 This excellent unit will play DVDs, VCDs, MP3s, CDs, and AM/FM radio. The built-in 3" TFT screen doubles as a control panel when listening to MP3s etc. It also has an auxiliary audio input for external MP3 or tape player etc. The player fits a standard DIN slot and has a detachable face and can be operated by the included remote. Mounting hardware included. • Resolution 500TV lines • 2 x video inputs • 1 x camera input • 45W RMS per channel • Frequency response: 20Hz - 20kHz $ 349 Cat: QM-3787 Great Audio Deals In-store! Free Call: 1800 022 888 for orders! www.jaycar.com.au COMPUTER PRODUCTS External 3.5" HDD Cases for IDE or SATA Drives Add gigabytes of storage to your PC or move large files from work station to work station with ease. This HDD case is made from strong aluminium and will accommodate a 3.5" hard drive. It has a USB 2.0 interface, fan cooling and an independent power switch. Supplied with pullback, software and USB interface lead. • Size: 117(W) x 183(D) x 50(H)mm Two types available: For IDE drives From • Silver Cat. XC-4664 $49.95 $ 95 For SATA drives • Black Cat. XC-4666 $59.95 49 1000 Mbps PCI Network Card Upgrade your home or work computers to blazingly fast gigabit speeds. Transferring large amounts of data can bring the common 100 Mbps network to a $ crawl. This 1000 Mpbs Ethernet card will you give you the bandwidth you need to quickly move large files. Cat: YN-8063 Combined Keyboard, Mouse and Monitor lead to provide a neat connection between your computer and PS/2 Switchbox or KVM. $ 19 95 Cat: WC-7570 USB Wireless Rechargeable Optical Mouse The pack contains a retractable USB charger to keep your mouse batteries topped up and the optical mouse has 400dpi resolution. Cat: YN-8066 Common specifications: • IEEE 802.11g wireless network compatible. Interoperation with IEEE 802.11b 11Mbps networks. • 64 / 128 Bit WEP encryption. • 54Mbps high speed transfer rate. • 40 - 100m indoor range. • 100 - 300m outdoor range. • Low power consumption. • Plug & Play • Compatible with Win98SE/2000/ME/XP PCMCIA Wireless Network Adaptor Cat. YN-8068 PCI Wireless Network Adaptor Cat. YN-8066 $ WHILE STOCKS LAST NO RAINCHECKS $ Cat: XM-5132 USB Roll Up Keyboard $ 19 95 Cat: XC-5148 $20 $ 79 Cat: XC-4668 Cat: YN-8068 34 95 Lightning Protector The video splitter takes the computer's video signal and sends it to two analogue monitors. The same image is displayed on both monitors. The splitter provides fast, flexible solutions for test bench facilities, data centres or video broadcasting such as remote monitoring, presentations, education and stock quotes etc. Supports VGA, SVGA, XVGA and Multi-Sync. Includes mains power adaptor. • Input DB15HD Male • Outputs DB15HD Female • 350 MHz video bandwidth • Max. resolution 2048 x 1536 <at> 60Hz • 72(W) x 43(H) x 121(L)mm Cat: YN-8098 $ 79 95 KVM switches allow you to use one keyboard, mouse and monitor to control several computers. These switches are designed to allow IT administrators to control servers, which don't require their own monitor or keyboard etc but are just as suited to the power user who has more than one computer on their desk. $ • Integrated cables on the PC side • Max Resolution: 2048 x 1536 pixels Cat: YN-8095 • Video Bandwidth: 400MHz 59 COMPUTER SECURITY Hard Drive Enclosure with Fingerprint Security 29 95 Cat: YN-8067 2 Port Automatic KVM Switch 29 95 Portable hard drives allow easy mobile data storage but can make confidential information vulnerable to embarrassing disclosure. This drive case prevents this by using onboard fingerprint recognition & encryption software to secure the data on the drive. 125mm long. USB powered. Hard drive not included. Was $99 34 95 Two Port Video Splitter 95 Keyboard, Mouse, Monitor Lead for PS/2 Switchbox or KVM This QWERTY keyboard rolls up for easy transportation or storage and is waterproof. You can spill coffee on it. Perfect for workshops, garages, food preparation areas, and travellers. • Compatible with Windows 98/2000/Me/XP $ A range of wireless networking cards to suit all computers and provisions. USB 2.0 Wireless Network Adaptor Cat. YN-8067 24 $ WIRELESS NETWORKING 802.11g PCI Wireless Network Adaptors PCMCIA Fingerprint ID for Laptops It slides into the PCMCIA slot in your laptop and utilises biometric technology to identify authorised users of the computer. Mainly intended for laptops, it can be used on any computer with a PCMCIA slot. • Software included. • 90(L) x 54(W) x $ 4.8(H)mm Was $129 $30 99 Designed for 2.4GHz systems. Mount where the cable enters the building so if lightning does strike near the antenna, high voltages will not be passed through to your equipment. Was $69.95 $20 $ WHILE STOCKS LAST NO RAINCHECKS 49 95 Cat: AR-3278 Wireless Network Access Point with 4 Port Router This router allows communication with up to four wireless network computers. It includes support for WAN, web based & remote management, auto detection & configuration of ISP, built in firewall, and more! • IEEE 802.11g & IEEE 802.11b compatible • Up to 54Mbps data rate • Static and dynamic routing • VPN pass through Was $69.95 $10 $ 59 95 Cat: YN-8086 Wireless Networking Starter Kit (2nd Edition) This book covers both the MAC and PC environments and will help you set up your wireless network like the Pros. It includes hints on network security and how to prevent outside attack. • Soft cover 560 pages $ 49 95 Cat: BP-7100 2.4GHz Parabolic Antenna 24dB Gain Designed for long term outdoor use in fixed locations and is suitable for all 2.4GHz wireless networks, both data and voice transmissions. Also excellent for 2.4GHz security surveillance transmissions. • Note: Picture may vary from stocked product. Cat: XC-4843 Free Call: 1800 022 888 for orders! www.jaycar.com.au $ 149 95 Cat: AR-3276 3 SIGHT & SOUND LOOKING FOR A PARTY DEAL? 15" Party Speakers • The big daddy of party sound! • 15" bass driver • 120 Watts RMS Power • Size 740 x 505 x 350mm Cat. CS-2515 Normally $179.00 each Buy 2 x CS-2515 & 1 x AA-0478 for only $499 Rack Mount Amplifier 2 x 160WRMS Features two 1/4" & two line level RCA inputs. • Separate level controls for each channel • Clipping & overload protection indicator LEDs • 3U rack mount • Power output: 2 x 118WRMS <at> 8 ohms • 2 x 158WRMS <at> 4ohms • 480(W) x 135(H) x 247(D)mm Cat. AA-0478 Normally $249.00 Save $108 Mini Stereo Resonator Speaker $ 99 95 Cat: AR-1870 This uber-cool gadget turns any flat surface into a speaker, creating high quality 360 degree sound. Great for travellers. Mains plugpack included. • Measures: 47(Dia) x 44(H)mm • Requires 8 x AA batteries for portable use *Laptop/mobile phone not included 1950s Styled Music Players With their 50s styling these music centres are sure to liven up any room and keep the party pumpin! Black and Chrome Cabinet • CD player with remote control • AM/FM analogue radio • 310(W) x 295(D) x 145(H)mm Was $89.95 Red Cabinet • Automatic turntable 33 & 45 RPM • CD player with remote control • MP3, CD-R & CD-RW compatible • AM/FM analogue radio • 315(W) x 290(D) x 165(H)mm Was $149.95 $ $30 $ 59 Cat: GE-4066 $20 129 95 Green Laser Display System Create a dazzling atmosphere at your next party with the green laser show. The unit comes fitted with a microphone that changes the pattern of the lasers to the beat of the music. • Mains 240VAC lead • Inbuilt microphone • 230(L) x 155 (W) X 60(D)mm Cat: SL-2935 4 This two channel system supports two separate microphones. Each channel has a separate balanced XLR output. A single unbalanced (mixed) line output is also available. The system includes 2 microphones and batteries, receiver unit and plugpack. $ 89 95 Cat: GE-4059 Smart and stylish design that will suit the home or office. It features a CD player, AM/FM radio, alarm clock, USB port, full function remote control and an iPod® docking station. What more could you ask for? • Recharges iPod® batteries • Measures 340(L) x 270(D) x 172(H)mm See website for full details iPod® not included 199 PARTY LIGHTING & EFFECTS 4 Colour Light Chaser Simple but effective! When music is playing they swtich in time with it. • Uses 240V 60W ES reflector lamps • Supplied with a red, Cat: SL-2942 yellow, green & blue globe $ Cat: AM-4078 Pro-Swivel Headphones These great looking pro-style headphones are ideal for DJs and other professionals. They feature an in-line volume control and a unique ear cup swivel action. • 32 ohm impedance • 40mm driver diameter $ 95 • Full range response • 100 dB sensitivity Cat: AA-2053 69 95 A great pair of headphones at a fantastic price! Setup is quick and easy and the sound clarity is excellent. The ultra-light design allows them to comfortably sit on your head and you’ll hardly know they're there. • Operation distance: up to 15m • Requires 2 x AA batteries $ 49 95 Cat: AA-2049 18 Watt RMS Stereo PA Amplifier This simple, low cost 18W per channel transistor amp is surprisingly loud! It is protected from accidental speaker wiring shorts and, if abused will simply shut down and reset after it has cooled off. It has a front panel microphone input, bass and treble controls as well as a master volume control. See our website or catalogue for full specifications. $ 39 95 Cat: AA-0472 Coloured Theatre Spotlight This sophisticated LED spotlight uses DMX protocols to enable remote control of colour and brightness via the theatrical three pin DMX control interface. Manual control also available. Made from lightweight ABS plastic and 240VAC mains powered. 137mm dia. $ 129 95 Cat: SL-2914 Rave Fog Machine 1 Litre Fog Juice available separately AF-1212 $11.95 199 Infrared Wireless Stereo Headphones Retro CD Player with iPod® Docking Station Produces clouds of white fog on demand by using the wired remote control. Use with laser light shows, mirror balls & other party lighting. • Mains powered • 70 cubic metres/min fog output • 800ml fog juice capacity • 330(L) x 160(W) x 140(H)mm $ 29 Cat: GE-4067 • GE-4069 Spare Stylus available separately $19.95 299 This handy turntable is perfect for the occasional bout of nostalgia and allows you to play those old vinyl records or make back-up copies in a convenient digital format. The turntable plays singles, EPs, albums and even your old 78s. • 33/45/78 rpm • 240 volt powered • Magnetic cartridge • NAB centre adaptor • Analogue or digital audio output $ Cat: GE-4068 $ 95 USB Turntable Wireless Microphone UHF Dual Channel Bubble Machine $ 79 95 Cat: AF-1214 Create instant, continuous bubbles with this affordable portable bubble machine! Great special effect for kids parties, weddings or anything. • Mains adaptor included. For best results use Bubble Mania Liquid (946ml) AB-1222 $6.95 $ 29 95 Cat: AB-1220 Free Call: 1800 022 888 for orders! www.jaycar.com.au SIGHT & SOUND 8 Way Speaker Selector with Impedance Matching Tweeters Perfect to use for general PA applications where long throw is required. Has built-in protection to allow them to handle 400WRMS. At high power levels, a PTC opens, allowing the tweeter to continue to play at a compressed power level. See our Website for full measurements $ From $ Cat Description RSN1141 Piezo CT-1932 RSN1142 Piezo CD Horn CT-1934 14 95 RRP $14.95 $24.95 HOME THEATRE High-End Speakers Equipped with light and rigid Kevlar/Paper composite yellow cone, fatigue resistant rubber surround, a strong CNC machined magnesium aluminium basket, oversized Neodymium magnet and high temperature Kapton voice coil, they have extremely high power handling and long cone excursion. Also features vented pole piece design for effective heat transfer and 8 ohm nominal impedance. • 4" high end speaker • Power handling: 25WRMS • Recommended enclosure ea volume 5 litres ported Cat: CW-2151 See our Website for full measurements Also available: Cat RRP Rec. Enclosure Size Power Volume 5" 60WRMS CW-2152 $74.95 8 litres ported 6.5" 60WRMS CW-2154 $89.95 15 litres ported 8" 150WRMS CW-2156 $139.95 25 litres ported 10" 150WRMS CW-2158 $159.95 75 litres ported $ 39 95 Glass Base Speaker Stand Good stands are essential for isolating your speakers from the floor and for optimal positioning from walls and furniture. These stands have glass bases for maximum isolation and machined heightadjustable carpet spikes for maximum stability. Gloss black. Dimensions: • Base: pr 278(W) x 300(D) x 12(H)mm • Speaker base: Cat: CW-2843 140(W) x 140(D) x 9.5(H)mm • Column: 280(H) x 78(Dia)mm Pedestal Speaker Stands also available Cat. CW-2846 400mm High. Black in colour. Sold in pairs for $99 $ 69 95 Mini Universal Speaker Brackets 5.8GHz AV Sender 249 A perfect match for a multi-room sound system! Turn on up to 8 pairs of speakers Cat: AC-1682 without worrying about your amplifier blowing up. Housed in a rugged metal case, speakers are easily connected via the strong spring terminals mounted on the rear, and then quickly turned on and off via the front mounted push buttons. • Up to two amplifiers can be connected and selected. • Max power: 100WRMS. 50 Watt RMS Faders Control extention speaker volume without miss-matching the amplifier output. A great solution for speakers near the BBQ or pool, etc. Cat: AC-1672 $ 19 95 $ Remote Controlled Two Input HDMI Switcher $ 24.75 Cat: CW-2804 $30 NOW WORKS WITH DIGITAL PAY TV REMOTES 169 Cat: AR-1840 HDMI Audio Video Switcher $20 69 A simple device for switching $ 95 between two high definition Cat: AC-1692 multimedia (HDMI) sources. Supplied with an I/R receiver fitted to a 2m cable. • Size 80(L) x 55(W) x 17(H)mm Was $89.95 Remote Controlled 4 Channel HDTV Input Selector $ 149 This four input HDMI selector routes HD Cat: AC-1694 video and $50 audio signals from the selected input to the HDMI output. The switcher also supports optical and coaxial audio inputs which are switched in unison with the HDMI channels. • Includes remote control and mains adaptor • Fully HDMI and HDCP compliant • 165MHz bandwidth Was $199 HDMI In-Line Repeater/Extender Extend the range of any HDMI device such as a monitor or TV, set-top box, DVD player, PC or gaming system up to 60 metres (powered). It will work with DVI components with an adaptor. Plugpack included. • Size: 62 x 22 x 20mm Was $79.95 $20 $ 59 95 Cat: AC-1698 5.1 Home Theatre Receiver Well designed, made of super strong ABS plastic, this attractive two- piece swivel bracket is easy to install and adjust (Phillips head screwdriver required). Primarily designed for mounting small / medium sized speakers for surround sound setups, or could easily be used for mounting security lights, CCD cameras....etc. • Wall mount section dimensions: 46(W) x 93(H) x 61(D)mm • Speaker mount dimensions: 41(W) x 83(H) x 61(D)mm New and improved. Transmit clear video and sound from sources such as your set-top box, TV, DVD, pay TV, camcorders and security cameras to anywhere in your home, office or building. Avoid the congestion and interference on the crowded 2.4GHz band & enjoy reliability and assured picture quality with this 5.8GHz AV sender. • Range of up to 50 metres (line of sight) • Built-in IR remote functionality • No messy wires Was $199 Not much you can't do with this receiver - home theatre, stereo, or dock your iPod® and use it for karaoke. The remote control operates all the functions of the amp, receiver and a docked iPod® • Analogue audio inputs • 2 microphone inputs with digital echo • Variable channel modes: 2 ch, Cat: AA-0471 sim 2.1, 3.1 & 5.1 • 435mm wide •iPod® not included $ 299 Watch one video source and record another simultaneously with this slimline selector. This 6 input unit supports component and composite video, S-video, digital audio with automatic or manual selection with the included remote control. $ • Unit dimensions: 280(W) x 130(D) x 60(H)mm 119 Cat: AC-1686 Dual Output Video Distribution Amplifier With two outputs, this amplifier is ideal for video distribution applications. Features automatic gain adjustment plus twin on-board brightness and contrast controls for optimum picture quality on each output .The unit is housed in a compact ABS plastic case with an integral mounting flange. • Requires 12VDC power • Size 140(W) x 28(H) x 65(D)mm $ 79 95 Cat: QC-3438 Economy Antenna Perfect for Caravans or space-conscious metropolitan areas Designed to enable positions in all horizontal, vertical or horiz/vert. polarities and is suitable for all transmitters across Australia. • Heavy duty construction • Stainless steel connection screws • Black UV resistant plastics • Boom length: 720mm • Max. width: 880mm • Check our website, catologue or in-store for full antennae range Free Call: 1800 022 888 for orders! www.jaycar.com.au $ 69 95 Cat: LT-3172 5 Ref Silicon Chip Aug. & Sept. 08 This ultra low distortion amplifier module uses the new ThermalTrak power transistors and is largely based on the high-performance Class-A amplifier which was featured in SILICON CHIP during 2007. This improved circuit has no need for a quiescent current adjustment or a Vbe multiplier transistor and has an exceptionally low distortion figure. Kit supplied with PCB and all electronic components. Heatsink and power supply not included. • Output Power: 135WRMS into 8 ohms and 200WRMS into 4 ohms $ 95 • Freq Resp. at 1W: 4Hz to 50kHz • Harmonic Distortion: Cat: KC-5470 <.008% from 20Hz to 20kHz Not available until part 2 in Sept. 08. 89 UHF Remote Controlled Mains Switch Ref Silicon Chip February ‘08 This UHF system will operate up to 200m and is perfect for remote power control systems etc. The switch can be activated using the included hand held controller or our KC-5461 water tank level sensor base station. Kit supplied with case, screen printed PCB, RF modules and all electronic components. $ 99 95 Cat: KC-5462 Temperature Controlled Soldering Station 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. See in-store or our website for full features. NEW KITS FOR ‘08 Emergency 12V Lighting Controller Kit Ultra Low Distortion 135WRMS Amplifier Module Refer Silicon Chip Magazine February ‘08 • Automatically supplies power for 12V emergency lighting during a blackout. The system has its own 7.5Ah SLA battery which is maintained via an external smart charger. Includes manual override and overdischarge protection for the battery. Kit supplied with all electronic components, screen printed PCB, front panel and case. Charger and SLA battery available Cat: KC-5456 separately. $ 69 95 Cat: TS-1560 Duratech 240V 25 Watt Soldering Iron Ideal for the hobbyist and handy person. Has a stainless steel barrel and orange cool grip, impact resistant handle. 29 12 95 $ Robot Arm Kit with Controller Anti-Static Wrist Strap 4.8 Volt Cordless Screwdriver $ 11.25 Cat: TH-1780 All metal construction with two internal collars. The head rotates freely making it ideal for drilling delicate PCBs or plastic cases. $ $ Every DIY Dad should own this little beauty that is comfortable and easy to use. • Bright LED torch • Magnetic bit holder • LED battery level indicator • 4 bitset included • Mains charger included 11.25 59 95 TOOLS $ 19 95 Cat: TD-2498 Cat: TH-1772 Tapered Reamer Ideal for enlarging and shaping holes in plastic, thin metals and wood. Tapers from 3 to 12mm $ 14.50 Laser Level with Tape Measure Use this tool to hang pictures, paintings or mirrors in your home, install shelving, lay tiles etc. The laser line projects up to 6m with a spread beam to create guide lines along walls etc. It also includes a handy 2.5m tape measure and a ruler on the side with inches on one side and millimetres on the other. $ Digital Vernier Calipers Cat: TS-1465 24 95 This arm is a must for budding robot enthusiasts and operates just like the real thing. It is capable of 5 separate movements and can easily perform complex tasks. Individual control is available for opening and closing the gripper plus control of wrist, shoulder, elbow and base rotation. The arm is supplied as a kit of parts and makes an excellent project for anyone interested in robotic construction and basic electrical connections. 100g lift capacity. Cat: KJ-8916 • Suitable for ages 8+ 95 Cat: TD-2130 $ Lets you run a stereo amplifier in 'Bridged Mode' to effectively double the power available to drive a single speaker. There are no mods required on the amplifier and the signal processing is done by the kit before the signals are fed to the stereo amp. Ideal for say, using a stereo amp as an occasional PA amp for social functions or using an old amplifier to drive a sub-woofer in a home theatre. Kit supplied with silk screened PCB and all specified components. Requires balanced (+/-) power supply. Ref: Silicon Chip Magazine June ‘08 Here's a new and Cat: KC-5464 completely updated version of the very popular low cost 12VDC electronic timer. It is link programmed for either a single ON, or continuous ON/OFF cycling for up to 48 on/off time periods. Selectable periods are from 1 to 80 seconds, minutes, or hours and it can be restarted at any time. Kit includes PCB and all specified electronic components. $ Pin Vice 99 Refer Silicon Chip July ‘08 Cat: KC-5469 Low Cost Programmable Interval Timer It has an adjustable wrist strap, coiled lead, and banana plug/alligator clip. • Expanded lead length approx. 1.8m. $ Bridge Mode Adaptor for Stereo Amplifiers 14 95 Cat: ST-3113 Spare tips Cat. TS-1466 $3.20 Adjustable Holesaw An excellent cutter designed to cut plaster board and ceiling tiles. Features calibrated hole size adjustment. Two sizes available: • 62 to 177mm hole size Cat. TD-2520 • 158 to 264mm hole size Cat. TD-2522 WHILE STOCKS LAST NO RAINCHECKS NOT AVAILABLE AT ALL STORES 6 $ 49 95 Both Models (ea) Simple and easy to use with digital readout • Accurate to 0.01mm • Metric or imperial measurment Storage Box Help Dad keep his garage neat and tidy with this niffty 24 compartment storage box. Measures: 370 x 65 x 285mm. $ 10 95 Cat: HB-6314 $ 39 95 Cat: TD-2082 Low Cost DMM 19 Ranges • 3.5 Digit • Transistor Test • Diode Test • 10A DC Current • Ideal First Meter • Compact Size $ 7 95 Cat: QM-1500 Free Call: 1800 022 888 for orders! www.jaycar.com.au POWER Mains Power Meter 150W 12VDC to 230VAC Isolated Can Inverter Designed to fit into your car's drink holder, this can-sized inverter alleviates the need for permanent mounting. Featuring a 150W output, this inverter is deceptively small but still has the grunt to power everything from $ 95 battery chargers right through to your Cat: MI-5121 laptop computer. 000’S SOLD The meter can tell you how much an appliance is costing to run and tracks the actual power being used. It can also display the instantaneous voltage or current being drawn as well as peak levels etc. 10A max rating. Was $39.95 $ 49 29 95 12V 7Ah SLA Battery Cat: MS-6115 $10 Universal 90W Laptop Power Supply This laptop power supply has adaptors to fit the major manufacturers' power sockets. It also displays the output voltage and automatically adjusts the output for the adaptor used. • 138(L) x 58(W) x 37(H)mm • Will charge newer Dell model laptops! Cat: MP-3474 $ 59 95 Home Theatre Powerboard 29 Full range of SLA Batteries in-store! Surge protection and filtering is provided to all your home theatre equipment connected to this powerboard as well as current protection via the in-built circuit breaker. • Provides protection to telephone, data via a network connection, satellite/cable TV and TV aerials $ 59 95 Alkaline batteries for every occasion. Cat RRP Pack Size 24 AAA SB-2331 $12.95 24 AA SB-2330 $12.95 40 AA SB-2332 $19.95 4 C SB-2320 $6.95 4 D SB-2321 $8.25 6 9V SB-2417 $13.95 6 95 (0.8A / 3.8A, IP65 rated) A truly versatile charger suitable for wet cell, gel and AGM SLA batteries from 1.25Ah to 120Ah. Computer controlled for optimum performance and rain proof as well. • Short circuit and reverse polarity protection • Anti-spark protection $ 95 • 1.8m charging cable, with interchangeable Cat: MB-3604 fly leads • Dimensions: 175(L) x 60() x 45(H)mm 79 Modified Sine Wave Inverters Eclipse Batteries Buy in Bulk & Save From 12V 5-Stage Car & Motorbike Maintenance Charger MAINS POWER ON THE GO Cat: MS-4024 $ Use as an emergency power source for security alarms or as a portable power source for VCRs or with solar $ 95 panels for remote power. Cat: SB-2486 • Leak proof • High discharge capacity • See catalogue, in-store or website for discharge characteristics Mains Power from your vehicle's battery anytime. Take your creature comforts with you when you go bush or on any road trip as these inverters will produce mains power from your vehicle's battery. A 150W inverter will run some laptops, lights, small TVs and recharge batteries. Inverters 300W and above will also run power tools, fluorescents and larger style TVs. Cat. Power Voltage Price MI-5102 MI-5104 MI-5106 MI-5108 150W 300W 400W 600W 12VDC to 230VAC 12VDC to 230VAC 12VDC to 230VAC 12VDC to 230VAC $48.95 $79.95 $139.95 $229.00 LIGHTING Rite Lights Simple one touch operation and super bright LEDs make these the most versatile, easy to install lights you'll ever purchase. No need for cords or plugs. • 3 styles available separately • Each requires 3 x AAA batteries Powertech Rechargeable Batteries • Packs of 4 Ni- MH rechargeable batteries. SB-1735 2400mAh AA $15.95 SB-1737 2000mAh AA $13.95 SB-1738 2500mAh AA $19.50 SB-1739 900mAh AAA $11.95 $ ST-3165 - Round Puck • 5 LEDs • 2 lighting modes • Measures 90mm Dia. $ 11 95 ST-3167 - Rectangle FOUR PACK SAVINGS In-Car Battery Charger 14 $ 14 95 Cat: ST-3166 $ • 6 LEDs • Rotatable light tube • Measures 220(L) x 56(W) x 30(H)mm 14 95 Cat: ST-3167 Emergency Road Flasher Power Point and Leakage Tester Test your power points using this versatile tester. It checks most types of power points within 110V to 240V for correct wiring and earth leakage circuit breaker trip levels. Recharges 2 x AA or 2 x AAA Ni-Cd or Ni-MH batteries. • Delta V voltage detection ensures the batteries are charged to their optimal levels for long life. • Keep a spare set of batteries topped up and ready to go, $ 95 wherever you are. Cat: MB-3552 9 95 Cat: ST-3165 ST-3166 - Square • 6 LEDs • 2 adjustable angled light blocks • Measures 100mm x 100mm From Models up to 2,000 watt available $ 19 95 Cat: QP-2000 Switch them on and place them on the ground to warn other motorists and guide them around a problem. • 3 high intensity LEDs $ 95 • Requires 2 x AAA batteries • 90(Dia.) x 25(H)mm Cat: ST-3185 9 Solar Powered Keyring Torch Features twin hibrightness LEDs and in-built solar cell. Just a few minutes exposure per day will keep the torch fully charged and ready for immediate use. • Approx 70mm long $ 14 95 Cat: ST-3385 Free Call: 1800 022 888 for orders! www.jaycar.com.au Keyring Torch Cool car-shaped keyring fob with three detachable key rings for valet parking and a built in superbright LED torch. Batteries incl. Measures $ 95 48mm long. 9 Cat: ST-3196 7 GREAT FATHERS DAY IDEAS - SUNDAY SEPTEMBER 7TH Miniature Golf Buggy with LCD Alarm Clock $5 OFF ALL THESE GOLF DESK ACCESSORIES This miniature 1:18 scale golf buggy with clock will make a cherished gift for any golf enthusiast. The windshield is a LCD screen which has full clock functions with a calendar and temperature setting. Batteries included. • 2 Sets of miniature golf clubs • Measures $ 95 140(L) x 75(W) x 100(H)mm Was $24.95 Cat: GH-1880 Golf Cart Pen Holder This miniature golf caddy pen holder includes three pens in red, blue and black which are cleverly shaped as real golf clubs. $ Was $19.95 19 14 Golf Course Smokers Set 95 39 95 $ Dynamo Wind Up LED Torch 39 8 6021 9699 9709 9678 9369 9905 4620 4365 9439 9476 9821 4965 4721 8832 9267 6788 4699 2822 9669 3899 4130 7155 3433 4799 6221 3100 3799 8337 3121 1614 39 95 Cat: GT-3515 $ 14 95 Play against the computer or a real opponent. The game can also suggest moves and hints if you need a bit of help. Software included. • 3 skill levels • Board 260mm square $ 44 95 Cat: GE-4094 GIVE DAD A JAYCAR GIFT VOUCHER Wireless Weather Station with Outdoor Sensor 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) $ USB Roll-up Chess Game Cat: ST-3337 Cat: SL-2811 YOUR LOCAL JAYCAR STORE Play Chess, Draughts, Reversi (Othello), 4-in-a-Row, Grasshopper or Nim against an opponent, the computer or recreate one of 320 famous Chess Masters games. It also has a teaching mode, different skill levels and an LCD to keep track of moves. • Requires 4 x AA batteries (Use SB- 2425) 29 95 Perfect for the Dad who loves travelling or camping. Just one minute of winding will give you 30 minutes of light. • 3 super-bright LED lights • Water-resistant • Internal rechargeable battery • While stock lasts - no rainchecks Cat: GH-1882 6-in-1 Electronic Games Board Cat: GH-1063 This will be the handiest light in the house. It clips on to any surface up to 25mm thick and the lamp can be removed and used as a separate torch. • Charger included. • Strong gooseneck • 18 superbright LEDs • 180mm high $ (approx) 95 14 95 GADGETS This mirror won't ever steam up. It also has a water resistant compartment where you can connect and play your iPod ® or MP3 player through the unit's speakers. • Twin LEDs • Stereo speakers • AM/FM radio • 245mm high • Requires 4 x AA batteries (Use SB-2425) Cat: SL-2715 Clip-on Rechargeable LED Lamp This attractive home weather station not only displays current weather data, it also forecasts the weather for the next 12 hours and shows the moon phase as well as the current time and sunrise/sunset times. A very informative system that is well designed & easy to use. • Measures indoor and outdoor temperature & humidity, & air pressure • Up to 30m transmission range • Indoor display 225mm wide This AM/FM radio not only has a stainess steel front but also a real golf ball and tee. The driver's shaft controls the volume and channel selection. • Measures 245(L) x $ 125(W) x 113(H) mm • Requires 3 x AA batteries (Use SB-2425) Was $19.95 Anti-Fog Shaving Mirror Solar Powered Garage LED Light Australia Freecall Orders: Ph 1800 022 888 The bunker with rake is the ashtray, the tee flips open at the push of a button to reveal your hidden cigarettes and the golf buggy becomes a $ 95 lighter at the push of the rear wheel. No-one will guess Cat: GH-1886 what little wonders this course contains. • 260(L) x 205(W)mm Was $24.95 19 Cat: GH-1884 Ideal for garages, gazebos and greenhouses, the 360° adjustable solar panel will allow for custom positioning. It's waterproof, features a cord-switch to operate, and is simple to install. • Solar panel and mounting bracket included • 2.4m cable and $ rechargeable enclosed Ni-Cd battery included Golf Driver AM/FM Radio $ Can’t make up your mind? Too hard to choose? Give Dad a Jaycar Electronics Gift Voucher so he can have all the fun of choosing for himself from our range of over 6,500 products. 69 95 Cat: XC-0339 Taren Point Tweed Heads Wollongong VICTORIA Coburg Frankston Geelong Melbourne Ringwood Springvale Sunshine Thomastown QUEENSLAND Aspley Cairns Ipswich Maroochydore Mermaid Beach Ph (02) 9531 7033 Ph (07) 5524 6566 Ph (02) 4226 7089 Ph Ph Ph Ph Ph Ph Ph Ph (03) (03) (03) (03) (03) (03) (03) (03) 9384 9781 5221 9663 9870 9547 9310 9465 1811 4100 5800 2030 9053 1022 8066 3333 Ph Ph Ph Ph Ph (07) (07) (07) (07) (07) 3863 4041 3282 5479 5526 0099 6747 5800 3511 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 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 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph Dunedin Ph Glenfield Ph Hamilton Ph Manukau Ph Newmarket Ph Palmerston Nth Ph Wellington Ph Freecall Orders Ph (03) 379 1662 (03) 471 7934 (09) 444 4628 (07) 846 0177 (09) 263 6241 (09) 377 6421 (06) 353 8246 (04) 801 9005 0800 452 9227 Free Call: 1800 022 888 for orders! www.jaycar.com.au 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. Q1 IRF9540 + S D K ZD4 16V 0.5W G 1k A 22 A TP1* 2.2k 1k FROM CHARGER K A 100 F 25V ZD1 16V 1W ZD2 3.3V 0.4W ZD3 3.9V 0.4W – K +7.2V VR1 5k K 3 IC1 LM311 1 A K 100 8 2 CHARGING  LED1 47k 7 4 2.2k A * SET VR1 FOR 7.2V AT TP1 WHEN BATTERY VOLTAGE IS 13.8V IRF9540 D LED ZD1–ZD4 A K K A G D S Charging controller for 12V lead-acid batteries Many low-cost chargers for 12V lead-acid batteries are little more than a step-down transformer and bridge rectifier. As a result they tend to overcharge a battery if left connected to it for an extended period. This simple charging regulator circuit is connected between the charger and the battery and is easily adjusted to prevent the battery being overcharged beyond the optimum level between 13.8V and 14.0V. P-channel power Mosfet Q1 is connected as a switch in the positive battery lead, controlled by LM311 comparator IC1. IC1 monitors the battery terminal voltage and compares a portion of the battery volt- age from trimpot VR1 with a fixed +7.2V at the inverting (-) input. This reference voltage is derived from the battery voltage via a shunt regulator circuit using zener diodes ZD2 and ZD3. When the battery voltage is below 13.8V, the voltage at TP1 will be lower than 7.2V. Therefore the output of IC1 will switch low, drawing current through LED1 and its series 100W and 1kW resistors and thus providing forward bias for Q1. Q1 switches on, allowing charging current to flow into the battery. As soon as the battery terminal voltage rises to 13.8V (or the preset voltage), TP1 rises above 7.2V and this causes the output of IC1 to switch high. The current through LED1 falls to zero and + Q1 is switched off, preventing any further charging. The 47kW resistor between pins 2 & 7 of IC1 provides about 0.5V of hysteresis so that the battery voltage will need to drop by 500mV or so, before the circuit can turn back on to provide TO 12V more charge. BATTERY Zener diodes ZD1 and ZD4 together with the 22W resistor are added to prevent overvoltage damage to either IC1 or Q1. Note that although Q1 is being used here as an on-off switch, it has an on-resistance – of about 0.2W and therefore needs to be provided with a good heatsink because of the heat dissipation during charging. We suggest a finned extrusion heatsink like the Jaycar HH-8566, which has a thermal resistance of 2.2°C/W. You’ll need to provide electrical insulation between the device tab and the heatsink though, because the Mosfet tab will be at positive battery potential. Setting up the regulator is easy, because LED1 provides direct indication of when Q1 is switched on to allow charging. All you need to do is connect the output terminals to either a battery or a DC power supply, with a voltage of between 13.8V and 14.0V. Then adjust trimpot VR1 until the voltage at TP1 is very close to 7.2V and LED1 is clearly at its switching point. Jim Rowe, SILICON CHIP. Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $13.95 PLUS P & P Available Aust, only. Price: $A13.95 plus $7 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 August 2008  57 Circuit Notebook – Continued – – FROM TRAIN CONTROLLER + TO TRACK D1 K A 12-18V AC IN + REG1 7812 IN +12V OUT K GND 1000 F 35V 100nF 100k 5 6 14 4 A A LED1  K C B Q1 BC338 A 6 1 2 IC1: 4093B IC2: 4013B 3 3 D S 1.2M 470k 14 Vdd 1 Q IC2a CLK Q R C Q2 BC338 E 1k 1k IC1a LED2  K B E 7 5 RELAY2 FWD/REV D6 A IC1b 10nF K RELAY1 RUN/STOP D5 8 9 2 11 4 D S Q IC2b CLK Q Vss R 10 7 13 LEDS 12 K A D2 A 22 F TANT K 8 9 IC1c 12 10 13 100k 270k D3 K IC1d 33k A 100nF 7812 11 100k B D4 K GND BC338 A 100nF E IN C D1,D5–6: 1N4004 A K GND OUT D2–4: 1N4148 A K Random direction control for a model railway layout This simple circuit connects between a model train controller and the train track. It automatically starts and stops the loco at random; sometimes it runs forward, sometimes in reverse and sometimes it just stops for a while. Two 12V relays are used to start or stop the loco and to run it in forward or reverse. Using relays avoids any problems with back-EMF sensing controllers. In the unpowered state, the two relays connect the train controller directly to the track, so the train runs according to the train controller setting. When Relay1 is energised, the train always stops. When Relay2 is energised, the train will run in reverse as long as Relay1 is deenergised. LED1 and LED2 indicate the on state of the relays (ie, they light when the relays are on). Here’s how it works: NAND gate 58  Silicon Chip IC1a is configured as an oscillator with a 20-second period and a high duty cycle. The output at pin 3 is only low for a few seconds every 20 seconds due to diode D2 and its series 470kW resistor. Two D-type flipflops, IC2a & IC2b, drive the two relays. Their D inputs are connected to two separate low-duty cycle oscillators based on gates IC1c & IC1d. They latch the D inputs on the low-to-high transition of IC1a. As a result, the state of IC1c and IC1d is clocked into the flipflops every 20 seconds. This results in a random state for the relays since all three oscillators run independently. However, the low duty cycle of both IC1c and IC1d (due to the parallel diode-resistor combinations) means the relays will be off more often than on, so the loco will run forwards most of the time. When IC1a goes from high to low it triggers a monostable based on IC1b which is connected to the SET input (pin 6) of flipflop IC2a. This turns on Relay1 and means the loco always stops for a few seconds every 20 seconds. This feature was included to avoid the possibility of the loco going instantly from forward to reverse or vice versa, with the danger of derailing. The circuit requires 10-12V DC to operate the 12V relays correctly and can be powered from the auxiliary AC terminals that are usually provided on train transformers. Geoff Nicholls, Hamburg, Germany. ($60) Editor’s note: a project providing a similar function, together with optoelectronic sensing of locomotive position, was featured in the July 1995 issue of SILICON CHIP. siliconchip.com.au S1 being the antenna under test. The antenna is connected to the circuit and the 100kW pot VR1 adjusted for a suitable reading on the meter, to indicate that the unit is operating. The frequency can then be determined by tuning for the signal with a shortwave receiver or by connecting a frequency counter to the termi- nal provided. The effect of nearby objects, long-term degradation in performance, losses and corrosion can be monitored by the setting required on the unit to achieve the same meter reading over a period of time. With experience, this can indicate a problem before a failure occurs. Transistor Q2 is connected as a grounded-base oscillator with FET Q1 providing buffering and the required phase change. FET Q3 is also a buffer to prevent any serious loading from the frequency counter, if used. Simply tuning to the signal with another radio is the easier method. The unit will test any antenna, with the proviso that there is a DC path through the system under test. Long wire or Beverage antennas, etc, will require a balun. If VR1 is fitted with a calibrated scale, it will allow documenting results as compared to the meter reading. The meter in the prototype was a VU meter salvaged from a defunct cassette recorder. Dayle Edwards, Taylorville, NZ. ($40) as determined by the components connected to pins 1, 2 & 3. This square-wave output drives complementary transistors Q1 & Q2 which act as buffers to drive the diode pump comprising D1, D2 and the 470mF capacitors. The resultant output of about -10V is then regulated to -5V by REG2, a 7905 regulator. The circuit provides 50mA at -5V but if higher currents are required, BD681 and BD682 Darlington transistors can be substituted for Q1 & Q2. L. Kerr, Ashby, NSW. ($45) METER – + 33k D D1 OA90 K A 56k B VR1 100k 100nF G Q1 MPF102 100nF S E 9V BATTERY A  LED1 Q2 BC557 K 47pF C 100nF 1k 10k 10pF 22k ANTENNA UNDER TEST Q3 MPF102 D G 10nF TO FREQUENCY COUNTER S 1k 1M LED OA90 A MPF102 K K A Antenna resonance indicator This circuit provides a quick and easy way to find the resonant frequency of antennas for HF marine installations. The circuit is a simple 2-terminal RF oscillator with its frequency-determining component BC547 B S G D E C Balanced supply rails from a 12V battery This circuit derives +5V and -5V regulated supply rails from a 12V battery. The +5V rail is derived directly via a standard 7805 3-pin regulator while the -5V rail is derived from an oscillator and a simple diode pump. A 4047 astable multivibrator provides an asymmetrical square-wave output at pin 10 of approximately 12V peak-to peak at about 580Hz, siliconchip.com.au August 2008  59 Circuit Notebook – Continued +5V 330 4.7k 12 IR Rx MODULE 13 IC1: 4093B 3  1 1 39k 2 2 4.7 F 1 3 A K 3 IC1a 5 10k* 6 D1 K 2 A 4 10nF 8 9 IC1b 14 11 IC1d 'CLOCK' 6 'START' 4 1 Vdd P0 P1 P3 IC2 5 PICAXE P2 -08 P4 SER 2 IN IC1c 10 7 3 'DATA' Vss D2 1 22k PROG SKT 2 8 3 10k 82k 100nF OUTPUT 7 100nF 0V D1, D2: 1N4148 A Universal IR remote control repeater This project came about during the development of a PICAXEbased home-theatre controller. The PICAXE has built-in infrared (IR) signal decoding capabilities but this is limited to the Sony Infrared Code (SIRC) 12-bit code. Since the hometheatre controller was to be used in conjunction with a Sony LCD TV, another solution was required. A check of the other IR remote controls that I had accumulated showed they all used a 32-bit data code based on the NEC IR format. This uses infrared pulses modulated K * VALUE MAY REQUIRE ADJUSTMENT IN THE RANGE 8.2k – 12k, DEPENDING ON COMPONENT TOLERANCES on a carrier of around 38kHz. IR receiver modules (available from Altronics and Jaycar) do the demodulation and provide a TTL-compatible output signal. While the PICAXE is an easily programmed PIC controller, the overhead of its internal interpreter makes it too slow to reliably process a 32-bit IR signal on its own. The main IR signal from an IR remote consists of an extended header pulse of between 4ms and 8ms carrier, followed by an “off” period of 2-8ms. These periods are constant for a particular manufacturer’s device but will differ between manufacturers/ devices/models etc. The “data” that follows is a series of 32 binary bits. The transmitter “on” period for each bit is constant at around 500ms with the following “off” period determining whether the bit is a 0 or 1. A “0” is transmitted as a ~500ms pulse followed by a break of a similar length. On the other hand, a “1” is a ~500ms pulse followed by a break of around 2000ms (2ms). A final “on” period, called a “lead out”, of ~500ms indicates the end of the data. Most IR remotes also transmit other pulse sequences but this receiver ignores these for simplicity. The circuit uses an IR receiver module, a CD4093 quad Schmitt trigger and a PICAXE-08M or larger. Looking for real performance? PERFORMANCE ELECTRONICS FOR CARS 160 PAGES 23 CHAPTE RS • Learn how engine management systems work • Build projects to control nitrous, fuel injection and turbo boost systems • Switch devices on and off on the basis of signal frequency, temperature and voltage • Build test instruments to check fuel injector duty cycle, fuel mixture and brake and coolant temperatures • Speedo Corrector, Turbo Timer & Digital Thermometer Projects Fro m the pub lish ers of Intelligen t turbo timer I SBN 0958 5229 9 7809 5 8 5229 4 $19.80 (inc GST) 4-4 TURBO B OOST & nitro us fuel cont rollers 6 NZ $22.00 (inc GST) How eng in manageme e nt works Mail order prices: Aust. $A22.50 (incl. GST & P&P); Overseas: $A26.00 via airmail. Order by phoning (02) 9939 3295 & quoting your credit card number; or fax the details to (02) 9939 2648; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. 60  Silicon Chip siliconchip.com.au The output of the IR receiver module is connected to a 4.7kW pull-up resistor. This output is normally high (+5V) and is pulled low when a 38kHz carrier is present. IC1a, configured as an integrator, detects the header pulse. Its output goes high about 3.5ms after the leading edge of the header pulse. Diode D1 causes the output to restore quickly after the pulse stops. The rising edge or end of each carrier pulse is used as a clock signal to indicate to the PICAXE that a bit can be read. IC1b is used to detect the longer “off” periods of the “1” bits. When data is present, the output of IC1b is pulled high by the presence of signal and stays high until the carrier is off for more than 1.5ms. This coincides with the longer “off” periods of the “1” bits. IC1c is wired as a monostable multivibrator. Its input is configured as a differentiator, triggered by the rising edge of the previous gate. This effectively creates a delayed pulse whenever a “1” bit is received. By the time the PICAXE has responded to the clock signal, the output of this monostable will indicate the inverse of the received bit. The PICAXE program is critical to the operation of the IR receiver. The PICAXE must be run at 8MHz or higher in order to decode and store the IR data. The program code structure has been optimised for speed and to save program space. This is necessary so that the smaller 08M or 14M chips can be used. The PICAXE chip must run faster than the incoming data so that overhead tasks, like saving data bytes and clearing the accumulator, can be completed before the next incoming bit needs to be read. As mentioned previously, the IR code consists of 32 bits or four bytes. The first two bytes indicate the device ID and the second pair indicates the device’s command. Dealing with the command pair first, the first byte indicates the command value (0-255) and the second byte is the 1’s complement or “inverse” of the first. This provides a level of error checking of the received signal. If the sum of the two command bytes is 255, then the data is treated as valid. The device ID pair of bytes can be interpreted in two ways, depending on the protocol adopted by the manufacturer. Most manufacturers use the 1’s complement algorithm described previously for checking the device ID code. However, some manufacturers use the full 16 bits (0-65,535) with no error checking as the device ID. Since the decoder must match the received device ID code with a lookup value, an error will cause the sequence to be ignored anyway. In addition to the device ID, the loop count for the header pulse “on” and “off” periods can be recorded in byte variables and can offer another Peter is this m Gee on winner th’s Peak At of a las Instrum Test ent level of device discrimination, where required. When used in proximity with other IR code controlled devices, the receiver program must discriminate between its own and foreign IR signals. This includes codes that are shorter than the 32-bit one used by this receiver. As an example, if Sony’s 12-bit code is detected, its sequence will be complete before the code receiver’s reception routine is halfway through, resulting in it “hanging”, waiting for further clock pulses. This will result in the next IR sequence completing the clocking of the 32-bits required, almost certainly causing the received code to be discarded after error checking. The receiver will thus ignore one button press but should synchronise to the following one. The RC values used with the integrators and differentiators are all ±5% and have proven to give reliable results. However, there may be circumstances where some adjustment is required, particularly with the data integrator time constant. Finally, the software for the PIC­ AXE-08 microcontroller can be downloaded from the SILICON CHIP website. The software filename is: “InfraDecoder-08M-V1.0.bas”. Peter Gee, Inglewood, WA. Contribute And Choose Your Prize As you can see, we pay good money for each of the “Circuit Notebook” items published in SILICON CHIP. But now there are four more reasons to send in your circuit idea. Each month, the best contribution published will entitle the author to choose the prize: an LCR40 LCR meter, a DCA55 Semiconductor Component Analyser, an ESR60 Equivalent Series Resistance Analyser or an SCR100 siliconchip.com.au Thyristor & Triac Analyser, with the compliments of Peak Electronic Design Ltd 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 silicon<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. August 2008  61 Pt.1: By JOHN CLARKE LED Strobe & Tachometer This versatile LED Strobe & Tachometer can be used to observe and measure the RPM of rotating machinery. It offers three different measurement methods and the readout is via a 2-line LCD module. I T’S EASY TO MEASURE the speed of rotating machinery with this versatile project. It uses three different “contactless” sensing methods, making it ideal for checking the RPM of objects such as rotating shafts, fans and model aircraft propellers. In addition, the strobe feature allows 62  Silicon Chip rotating machinery to be effectively “frozen” for close visual inspection. The strobe is based on a high-brightness white LED and can also be used to provide basic stroboscopic speed measurement. Alternatively, speed measurements can be made using either an infrared reflective optical pickup or a slotted disk/photo-interruptor pickup. Strobing Many people consider strobes as just a party effect, for use in discos and other venues. A typical disco strobe flashes at about four times a second siliconchip.com.au Warning! 1000 RPM TACHOMETER STROBE LIGHT MACHINE BASIC STROBOSCOPIC MEASUREMENT Fig.1: using a strobe light to measure rotational speed. The strobe flash rate is manually adjusted until the machine appears to stop (see text) and the result read from the LCD. Flashing lights, particularly in the lower frequency range from about 5Hz (300 RPM) and upward can induce seizures in people subject to photosensitive epilepsy. Flashing lights can also trigger a migraine attack. It is recommended that people prone to these effects avoid stroboscopic lights. SLOTTED DISK 1000 RPM TACHOMETER MACHINE PHOTO INTERRUPTOR STROBE LIGHT (OPTIONAL) TRIGGERED MEASUREMENT VIA SLOTTED DISK Fig.2: this technique uses a photo-interruptor assembly to send a series of trigger pulses to the tachometer. The tacho counts these pulses and shows the result on the LCD. In this case, the strobe light is optional – it is triggered by the photo-interruptor and used to observe the machine. REFLECTIVE STRIP ON SHAFT 1000 RPM TACHOMETER STROBE LIGHT (OPTIONAL) REFLECTIVE MACHINE OPTICAL PICKUP TRIGGERED MEASUREMENT BY REFLECTION Fig.3: this triggered measurement technique uses the tacho to count the pulses from a reflective optical pickup. and the strobing effect makes people appear to move in a jerky manner. That’s because, at night, you only see each person’s position when the strobe flashes. The intermediate positions between flashes are not seen. Strobing rotating machinery gives much the same effect, depending on the strobe frequency and the RPM of the rotating part. If the strobe is set to flash at a rate of once per rev, then the rotation will appear to stop. The reason for this is simple – the machine will be in the same position each time the strobe flashes. In fact, the effect is so convincing that it can be dangerous. You must be alert to the fact that the machine must not be touched, since it is still actually moving and could cause serious injury. siliconchip.com.au Other strobe effects also become apparent as the strobe frequency drifts out of step with the rotational frequency. For example, if the strobe flashes slightly faster than the rotational speed of the machine, then the machine will appear to rotate slowly backwards. Conversely, if the strobe flashes at a slightly slower rate than the rotational speed of the machine, the machine will appear to rotate slowly forward. One area where this is often apparent is in western movies, where the wheels of a stage coach initially appear to slowly rotate backwards and then stop while the stage coach is still moving. That happens because movies are shot at a rate of 24 frames/s and this has the same effect on the wheels spokes as a strobe. Initially, the wheel spokes are travelling too slowly to keep up with the strobing effect of the frame rate. Then, as the speed increases, the wheels appear to stop before finally appearing to rotate forwards. If we know the number of spokes in the wheel, we can even calculate its rotational speed when it appears to be stopped. For example, if the wheel has eight spokes, then its speed is equal to 1440 (ie, the number of frames per minute) divided by eight, or 180 RPM. Similarly, the rotational speed of any machine can be measured by setting the strobe rate so that the motion appears to stop. Note, however, that you have to set it to the highest speed at which the machine appears to stop, since the same effect will also occur if strobing takes place at 1/2-speed or 1/3-speed, or 1/4-speed, etc. You also have to take into consideration the number of blades on a fan or propeller, or the number of marks on a shaft. For example, if there are two blades on a prop, then the prop will also appear to stop if strobed at twice the rotational speed. The solution to this problem is to place a single mark on the shaft or a propellor, etc. Fig.1 shows how the unit is used with a strobe to measure machine rotation. Note that if the strobe is set at twice the speed of the machine, there will appear to be two reference positions, each 180° apart. However, if the strobe is set at half rotational speed, there will be one reference position but it will appear dimmer than when the strobe is set at the correct speed. Photo-interruptor Fig.2 shows another way to measure rotational speed. In this case, a trigger signal is sent to a tachometer from a sensor attached to the machine. This August 2008  63 5MHz OSCILLATOR COUNTER LCD READOUT CALCULATE COMPARE VALUE FOR DISPLAYED RPM COMPARE 1000 RPM RPM FINE ADJUST STROBE RPM 'SET' SWITCHES GENERATOR MODE OF OPERATION Fig.4(a): this is the block diagram for the generator operating mode. The Up & Down “RPM Set” switches and a fine adjust pot on the tachometer set the stroboscope’s flash rate, while the LCD shows the corresponding reading in RPM, TRIGGER INPUT 5MHz OSCILLATOR COUNTER EDGE DETECTOR & DIVIDER CAPTURE CLEAR CALCULATE RPM 1000 RPM LCD READOUT STROBE TRIGGERED MODE OF OPERATION Fig.4(b): the triggered mode of operation. In this mode, the counter counts the number of pulses from a 5MHz oscillator between each successive external trigger signal. This value is used to calculate the RPM which is then displayed on the LCD. sensor could be either an optical trigger or Hall effect trigger that is interrupted by a rotating vane or magnet. As the shaft rotates, it sends a series of pulses to the tachometer. The tacho­ meter measures the frequency of these trigger signals and calculates the RPM for display on the LCD. As Main Features • • • • • • • • • • RPM and frequency readout on LCD panel Generator or triggered strobe Can be triggered via slotted disk or reflective light Adjustable flash period Fine frequency adjustment in generator mode Wide frequency range 1 RPM resolution Divider options when triggering Triggering indicator Readout averaging 64  Silicon Chip an option, the strobe can also be fired in synchronisation with the sensor. The more rotating vanes used on the trigger, the greater the number of pulses generated for each rotation of the shaft. As a result, the unit can be set to a division ratio from 1-8, so that the displayed reading is correct. For example, if there are eight pulses per rotation, the division ratio is set to eight to get the correct reading. A 0.5 divider has also been included. This can be used if the sensor is being triggered by a shaft that runs at half the speed of the shaft we want to measure. For divisions from 2-8, you also have the option of firing the strobe on any one of the trigger signals. For example, if there are eight pulses per rotation, you can have the strobe fire either on the first pulse, the second pulse, the third pulse or on any other pulse up to the eighth pulse. In addition, the pulse edge can be selected so that the strobe fires when the pulse signal goes high or when it goes low. Each of these triggering points will provide a different view of the machine – ie, the strobed position of the machine will vary. Reflected IR A third method of measuring the RPM of a rotating machine is shown in Fig.3. This is a purely a non-contact method and relies on light reflection from the machine. In some cases, a reflecting strip will have to be attached to the machine in order to get sufficient variation in the light reflection as the machine rotates. However, for rotating parts such as propeller or fan blades, the brightness variation should be sufficient without adding any reflective material. In this measuring mode, an infrared (IR) light source is shone onto the machine and the resulting reflected light variations detected using an infrared photodiode. Using infrared prevents other light sources such as fluorescent lights from affecting the reading. Strobe duration When using a strobe, the duration of the flash determines just how much of the machine’s rotation can be seen. Ideally, the flash should be as short as possible to prevent blurring of the strobed image (ie, we don’t want the machine to move too much during the flash period). Traditional strobes use Xenon tubes and these produce short, bright flashes that are ideal for strobing rotating machinery. However, this circuit uses a high-brightness white LED and its output is much lower than that from an Xenon tube. As a result, the flash period needs to be a compromise between brightness and the amount of movement that can be tolerated during the flash. And in case you’re wondering, most white LEDs can be driven with very short pulse widths for use in strobe applications. If you are not convinced, read the “Busting a Myth” panel in Pt.2 next month. For our LED strobe, the flash period can be set anywhere between 32ms and 6.5ms. A longer flash period gives a brighter light but in practice, the period needs to be set to suit the application. The faster the machine spins, the lower we need to set the flash duration to prevent “blurring” of the strobed machine. For example, if the machine is rotatsiliconchip.com.au ing at around 5200 RPM, then we need to set the flash duration to just 32ms to limit the movement during this period to 1°. However, at just 166 RPM, the flash duration can be increased to 1ms for 1° of movement. As an alternative to a fixed flash period, there is an automatic mode which sets the flash period as a percentage of the measured RPM. This percentage can also be manually adjusted from 1-10% in 1% steps. Note, however, that these percentage settings are not obtainable at very high or very low RPM values, due to the limited flash duration range (32ms to 6.5ms). Operating modes In order to carry out the different measurement techniques depicted in Figs.1-3, the unit has two different operating modes: (1) generator and (2) triggered. Block diagram Fig.4(a) shows the generator mode of operation, while Fig.4(b) shows the triggered mode. The generator mode is used for basic stroboscopic measurements and when this mode is selected, the unit directly drives the strobe light. In operation, the tachometer is initially adjusted using Up & Down pushbuttons and this sets the strobe rate and adjusts the corresponding RPM reading on the LCD. Each pushbutton alters the RPM setting in 100 RPM steps, while an adjacent knob provides for fine adjustment to 1 RPM resolution. The resulting LCD readout shows both the RPM (1 RPM resolution) and the frequency in Hz (.01Hz resolution). The alternative triggered mode is used to make the measurements depicted in Figs.2 & 3. In this mode, the tachometer is triggered by the pick-up sensor and the LCD shows the RPM and the frequency of the incoming trigger signal. The strobe light is optional and is also triggered by the pick-up sensor. As discussed above, the sensor can be either a slotted disk and photointerruptor assembly or an optical pick-up relying on reflected IR light. Note that, in this mode, the RPM reading cannot be adjusted manually and the tachometer reads the rotational speed according to the trigger pulses from the sensor. If there is more than one trigger pulse per revolution, the strobe can siliconchip.com.au The strobe technique is used for measuring the speed of fan blades and for “freezing” the motion while the machine is running. Alternatively, the infrared optical pickup method can be used for measuring the RPM of fans and model aircraft propellers, since the blades usually give good reflection variations. The infrared optical pickup method is also ideal for measuring the rotational speed of shafts. A reflective strip attached to the shaft provides the required variations in the amount of reflected light as the shaft rotates. be set to fire on any one of these by pressing either the Up or Down switch, to shift to the next trigger edge. In addition, the division ratio must be set to get the correct reading. How the tacho works The way in which the tachometer works to measure the incoming RPM pulses is rather unconventional. The traditional method of measuring frequency is to count the number of incoming pulses over a set period, usually one second. This is quite an acceptable method when the frequency is high and a lot of counts are obtained during the 1s period. However, for RPM readings, the incoming frequency is usually relatively low and in most cases there just aren’t enough counts over a 1s period to ensure sufficient accuracy. For example, at 1000 RPM, the incoming frequency would be just 16.66Hz (assuming one pulse per rev) and so we would read either 16Hz or 17Hz on a counter. After multiplying by 60 to convert to RPM, the display would show either 960 RPM or 1020 RPM. In other words, there would be a 60 RPM uncertainty in the reading. Of course, we could count the signal over 10s or even 100s to get 6 RPM or 0.6 RPM resolution. However, 10s is a long time to wait for a reading update and a machine can vary its RPM value quite significantly during that time. As for waiting 100s, forget it. So how do we measure RPM with high resolution and a fast update time? Fig.4 shows how it’s done. For the triggered mode of operation, the tachometer utilises a 5MHz oscillator and a counter. The counter is configured to count the number of pulses from the 5MHz oscillator between each trigger signal. For example, if the trigger signal August 2008  65 REG1 7805 +5V 100 F 16V 27pF X1 20MHz 27pF 16 15 FINE FREQUENCY ADJUST (RPM) OUT 1k 100nF 4 14 Vdd MCLR K 100 F 16V A OSC2 S4 ZD1 16V 1W RB4 10 11 39  5W 220 C B IC1 PIC16F88-I/P 10k 4 13 6 18 RA1 1 RA2 17 RA0 2 RA3 TO TRIGGER CIRCUIT 6 CON3 Vdd RS CONTRAST EN D7 D6 D5 D4 D3 D2 D1 D0 GND 2 14 13 12 11 10 9 8 7 3 LCD CONTRAST VR2 10k 10 F R/W 5 7 RB1 9 RB3 8 RB2 RB0 7805 GND BC337 1nF S1 Vss 5 S2 B S3 E MODE SC – Q1 BC337 1 12 16 x 2 LCD MODULE 2008 S5 TO 1W WHITE LED AN4 RB7 3.5mm JACK SOCKET CON1 CON2 + 220 12V DC INPUT – 470 F 16V LL LED ON/OFF RB6 1k A + K E 3 100nF 2.2 D1 1N4004 OSC1 RB5 VR1 10k IN GND 100 F 16V POWER 10 DOWN C IN GND OUT UP LED STROBE & TACHOMETER ZD1 A D1 K A K Fig.5: the circuit is based on a PIC16F88-I/P microcontroller (IC1) and an 16 x 2 LCD module. External trigger signals are applied to RB0 of IC1 via CON1, while RB4 & RB5 drive the white-LED strobe via transistor Q1. Power comes from an external 12V DC plugpack, with regulator REG1 providing a +5V supply rail for IC1 and the LCD. has positive going edges that are 60ms apart, the counter will count to 300,000 between each pulse. The value of the count is then stored in a capture register and the counter cleared so that it is ready for the next count. Next, a calculation is made to derive the RPM. This simply involves dividing 300,000,000 (ie, the number of pulses from a 5MHz counter in one minute) by the register value. So if the register value is 300,000, we get 1000 RPM. Another calculation is made to derive the trigger frequency (50,000,000 divided by the register value). This 1000 RPM calculation is made in just 60ms and has a resolution of 1 in 300,000, thus giving a display resolution of 1 RPM. This is significantly better than the method first described, which involved counting the 16.66Hz signal over a 1s period. 66  Silicon Chip For the Generator mode, the operation is slightly different. The counter still counts the 5MHz signal but in this case, a calculation is made to determine the value that the counter must reach to provide the required RPM value and strobe flash rate. In this case, this calculation is 300,000,000 divided by the RPM setting. The calculated value is placed in the compare register and when the counter reaches this value, the strobe is fired. The counter is then reset and counts again to fire the strobe at the set RPM rate. Circuit details Fig.5 shows the full circuit details for the LED Strobe & Tachometer. It consists of a PIC16F88-I/P microcontroller (IC1), a 16x2 LCD module and not much else. So in spite of the seemingly complex operation, the circuit itself is really very simple. Most of the “smarts” are hidden inside the micro, which is really the heart of the circuit. It runs at 20MHz using crystal X1 as its timebase and this signal is also divided by four to derive the 5MHz oscillator that’s used for the RPM calculations. In operation, IC1 monitors the external trigger signal (if one is present) at its RB0 input, while RB1, RB3 & RB2 monitor the Up, Down & Mode switches respectively. In addition, IC1’s AN4 analog port monitors the position of potentiometer VR1 which is used for fine RPM adjustments. Note that RB1-RB3 have internal pull-up resistors, so these inputs are normally pulled high to +5V. When a switch is closed, the associated input is pulled to 0V and so IC1 can detect this button press. siliconchip.com.au IC1 also directly drives the LCD module. RA0-RA3 are the data outputs, while RB6 and RB7 drive the register select and enable lines respectively. Trimpot VR2 sets the display contrast voltage. When IC1 is operating in trigger mode, the signal applied to the RB0 input is used as the trigger for RPM measurements. This input is protected from excessive current using a 1kW series resistor, while a 1nF capacitor filters out any transient voltages to prevent false counts. The external trigger circuit is connected via a 3.5mm jack socket and is fed with a +5V rail via the socket’s ring terminal and a 2.2W resistor. The tip carries the external trigger signal and in the absence of signal, is pulled high via a 10kW pull-up resistor to the +5V rail. Potentiometer VR1 is connected across the 5V supply and the wiper can deliver any voltage from 0-5V to the AN4 analog input of IC1. IC1 converts this input voltage to a digital value to set the fine frequency adjustment over a 100 RPM range (but only when IC1 is operating in the generator mode). Note that the operational range of VR1 has been deliberately restricted to 0.54-4.46V. This has been done because potentiometers often have abrupt resistance changes towards the ends of their travel. Using a 0.54-4.46V range ensures that the more linear section of the potentiometer is used. Driving the strobe IC1’s RB4 and RB5 outputs provide R Fig.6: the photointerruptor trigger circuit uses a slotted LED and phototransistor package, plus a rotating vane assembly attached to the machine. T S 150 A LED 3.5mm PLUG (TO TRIGGER INPUT CON1) C  PHOTO TRANSISTOR  A K E K PHOTO INTERRUPTOR TRIGGER CIRCUIT the strobe LED drive. Each output can source about 20mA into the base of transistor Q1 which turns fully on each time a positive going pulse is applied. Each time Q1 turns on, it also turns on a 1W high-brightness white LED which is connected via CON3 (provided S5 is closed). Power for this LED is derived from the +12V supply rail via reverse polarity protection diode D1. A 39W 5W series resistor limits the peak LED current to about 220mA. This resistor value was chosen so that even if the supply is 15V, the current will still be below the 350mA maximum for a 1W Luxeon LED. Switch S5 allows the strobe LED to be manually switched on or off. Power supply Power for the circuit is derived from an external 12V DC plugpack and this is fed in via DC input socket CON2 and power switch S4. A 470mF 16V capacitor decouples the +12V supply which is then fed to regulator REG1 and the strobe, while a 10W resistor and a 100mF capacitor provide additional decoupling for the supply to REG1. Zener diode ZD1 clamps the input to REG1 to 16V. REG1’s +5V output is used to supply both IC1 and the LCD. This rail is decoupled using a 100mF capacitor directly at the regulator’s output, while an additional 100mF capacitor and a 100nF capacitor bypass the supply close to pin 14 of IC1. A 10mF capacitor provides additional bypassing for the supply at the LCD module. Photo-interruptor circuit Fig.6 shows the circuit for the photointerruptor. It’s very simple and is based on a slotted LED and phototransistor package, plus a vane assembly that rotates in the slot. Power for the circuit comes from the +5V rail of the main circuit and is applied via the ring (R) terminal of a 3.5mm jack. A 150W resistor limits the 150 R T A IR  LED1 3.5mm PLUG (TO TRIGGER INPUT CON1) 100k IC2: LM358 10 F 2 3 IC2a 5 1 6 100k 4 IR  SENS 1 A S 100 F 10k K K E C 1k 8 IC2b 7 150 ACTIVE AREA 470k IR LED IR SENSOR 1k 100 F A K K A IR REFLECTOR AMPLIFIER CIRCUIT Fig.7: the IR reflector amplifier uses an IR LED and an infrared photodiode (IR SENS1) to pick up the reflected light pulses. The resulting current variations through IR SENS1 are then fed to current-to-voltage converter stage IC2a which in turn drives amplifier stage IC2b. IC2b’s output then drives the trigger input of the main tachometer unit. siliconchip.com.au August 2008  67 Table 1: Capacitor Codes LCD MODULE X1 20MHz 100nF IC1 PIC16F88-I/P 10 F 100nF 4-WAY SOCKET STRIP 1k 1nF 1k 100 F 100 F CON2 + 10 ZD1 VR2 10k 470F 16V 27pF REG1 7805 100 F CON1 Value mF Code IEC Code EIA Code 100nF 0.1mF 100n 104 1nF .001mF 1n0 102 27pF NA 27p 27 D1 22 1 13 11 9 7 5 3 1 220 220 10k 2.2 14 14 13 27pF 18070140 CON3 3-WAY SOCKET STRIP VR1 39  5W Q1 E B ORTS DEL MAIN BOARD S4 3-PIN SIL HEADER (UNDER BOARD) S1 04107082 SWITCH BOARD S2 LED STROBE SWITCH S3 4-PIN SIL HEADER (UNDER BOARD) S5 Fig.8: follow this layout diagram to install the parts on the main board and to assemble the small switch board. Take care with the orientation of the switches – they must all be installed with their flat sides to the left. Below: this view shows the completed main board assembly prior to mounting the LCD module and switch board. LED current to around 20mA. With no vane in the slot, the photo­ transistor is illuminated by the LED. As a result, the phototransistor turns on and its collector pulls pin 6 of microcontroller IC1 low via the tip connection of the jack socket. Conversely, when a vane passes through the slot, 68  Silicon Chip the phototransistor turns off and its collector is pulled to +5V via the 10kW pull-up resistor on the main circuit IR reflector amplifier The optical pick-up circuit is a bit more complicated – see Fig.7. It’s based on an infrared LED (IRLED1), an infrared photodiode (IR SENS1) and an LM358 dual op amp (IC2). The infrared LED is powered via a 150W resistor from the +5V 3.5mm jack connector ring terminal and operates continually while ever power is applied. As mentioned previously, the photodiode is aimed at the rotating machine and the light is reflected back to the photodiode via a blade or a reflective strip attached to a shaft. The infrared photodiode is connected to pin 2 of IC2a. This op amp is wired as an inverting amplifier and operates as a current-to-voltage converter. As shown, its non-inverting (pin 3) input is biased to about 0.5V by a voltage divider consisting of series 10kW and 1kW resistors connected across the 5V supply. In operation, the current through the photodiode varies with the reflected light and these current variations are converted to voltage variations at IC2a’s pin 1 output. This signal is then AC-coupled to pin 5 of IC2b via a 10mF capacitor. IC2b is connected as a noninverting amplifier with a gain of 471, as set by the 470kW feedback resistor and the 1kW resistor at the inverting input. As with IC2a, IC2b is also biased to about 0.5V by the series 10kW and 1kW resistors across the 5V supply. The 100kW resistor between pin 5 and this 0.5V supply ensures that, in the absence of signal from IC2a, IC2b’s output normally sits at 0.5V. Each time sufficient light is reflected onto the infrared photodiode, IC2b amplifies the signal from IC2a and its output swings to about 4.5V. This signal is then fed to the tip of a 3.5mm jack plug via a 150W isolating resistor and applied to pin 6 of IC1. Construction The main LED Strobe and Tacho­ meter circuit is built on two PC boards: a main PC board coded 04108081 (115 x 65mm) and a switch PC board coded siliconchip.com.au The 14-way DIL header is installed from the underside of the LCD module and soldered to the pads on the top of the module’s PC board. 04108082 (52 x 15mm). This switch board plugs into the main board and the assembly is housed in a bulkhead style case with a clear lid. Another two boards are used for the photo-interruptor and IR reflector amplifier circuits. The photo-interruptor board is coded 04108083 and measures 50 x 25mm, while the IR reflector amplifier board is coded 04108084 and measures 53 x 32mm. Fig.8 shows the main board assembly details. Begin by first checking the board for any defects. Check also that the hole sizes for the connectors and potentiometer VR2 are correct by test fitting these parts. Enlarge these holes so that the parts do fit, if necessary. In addition, the holes for the four corner mounting screws, the LCD mounts and for REG1 must be 3mm in diameter. Check also that the PC board is cut and shaped (note the corner cutouts) so that it fits into the box. Once these checks have been completed, install the two wire links then solder the resistors in position. Table 2 shows the resistor colour codes but you should also check each value using a digital multimeter (DMM) before soldering it to the board. Follow these parts with the 10 PC stakes. Seven PC stakes are used for Once the header has been attached, the LCD module is plugged into matching socket strips on the main board and secured to four M3 x 9mm Nylon spacers. The main PC board assembly is completed by plugging the switch board into its matching header strips. Table 2: Resistor Colour Codes o o o o o o o o o siliconchip.com.au No.   1   2   2   4   2   2   1   1 Value 470kW 100kW 10kW 1kW 220W 150W 10W 2.2W 4-Band Code (1%) yellow violet yellow brown brown black yellow brown brown black orange brown brown black red brown red red brown brown brown green brown brown brown black black brown red red gold brown 5-Band Code (1%) yellow violet black orange brown brown black black orange brown brown black black red brown brown black black brown brown red red black black brown brown green black black brown brown black black gold brown red red black silver brown August 2008  69 The main PC board assembly is secured to integral pillars inside the case using four self-tapping screws. Be sure to fit heatshrink tubing over the lead connections to the switches and the PC stakes, to prevent the leads from breaking after they have been soldered. potentiometer VR1, three for its terminals and four more to support its body. The remaining three PC stakes are used to terminate the wiring from switches S4 & S5. Next, install diode D1, zener diode ZD1 and a socket for IC1, taking care with their orientation. That done, install the 3-way and 4-way single inline (SIL) socket strips that are used to mount the switch board. These socket strips made by cutting down an 8-pin IC socket using a hobby knife or side cutters. Clean up the edges of these socket strips with a small file before soldering them in position. Similarly, the LCD module is conVR1 LCD MODULE BOX 39  5W MAIN BOARD MOUNTED ON INTEGRAL STANDOFFS USING SMALL SELF TAPPERS nected via a 14-pin DIL socket strip. This is made by cutting a 14-DIL IC socket to produce two 7-way strips which can then be installed adjacent to each other on the board. The capacitors can go in next. Note that the electrolytic types are polarised and must be oriented as shown. Note also that the 470mF capacitor goes under the LCD module and must be mounted horizontally (ie, with its body flat against the PC board). The 100mF capacitor to the left of IC1 must also lie horizontally – see photos. Next on the list is regulator REG1. As shown, this device also mounts horizontally on the PC board, with its PC BOARD LCD MODULE ON 9mm LONG M3 TAPPED SPACERS 6mm LONG M3 SCREWS Fig.9: this diagram shows how the main board assembly is secured to the case pillars and how the LCD module is secured to the M3 x 9mm Nylon spacers. 70  Silicon Chip leads bent down by 90° to go through the relevant holes. To do this, first bend the two outer leads down about 9mm away from its body and the middle lead down about 6mm away. The device is then fastened into position using an M3 x 6mm screw, nut and washer and its leads soldered. Don’t solder REG1’s leads before bolting its tab down. You could crack the PC tracks or lift the solder pads as the nut is tightened down if you do. The DC sockets, the 3.5mm PCmount jack socket and trimpot VR2 can now be installed, followed by potentiometer VR1. Before mounting VR1 though, it will be necessary to cut its shaft to a length of about 14mm (from the end of its threaded boss), to suit the knob used. As shown in the photos, the pot is mounted upright on the PC board, with its body soldered to four PC stakes. Note that you will have to scrape away some of the coating on the pot body at each solder point, in order to get the solder to “take”. Once it’s in position, solder its three terminals to their adjacent PC stakes. The LCD module is connected via siliconchip.com.au Parts List Main Unit 1 PC board, code 04108081, 115 x 65mm 1 PC board, code 04108082, 52 x 15mm 1 bulkhead case with clear front, 120 x 70 x 30mm (Jaycar HB6082 or equivalent) 1 12VDC 350mA plugpack 1 1W Luxeon white LED or Cree XR-C white LED with collimator lens 1 small torch to house LED and optics 1 2.5mm DC line plug 1 LCD module with backlight (Jaycar QP-5516 or equivalent) 1 16mm 10kW linear potentiometer (VR1) 1 10kW horizontal trimpot (code 103) (VR2) 1 knob to suit potentiometer 1 20MHz parallel resonant crystal (X1) 2 PC-mount 2.5mm DC sockets 1 PC-mount stereo 3.5mm jack socket 3 click-action PC-mount switches (S1-S3) 2 sub-miniature SPDT toggle switches (S4,S5) 1 14-pin DIL header (2.54mm pin spacing) 1 4-way SIL header (2.54mm pin spacing) 1 3-way SIL header (2.54mm pin spacing) 1 14-pin DIL IC socket (cut to suit the 14-pin DIL header) a 14-way pin header strip at one end and is supported on four M3 x 9mm at its corner positions. We’ll describe how the header strip is fitted to the LCD module shortly. For the time being, just fit the four Nylon spacers to the PC board and secure them using M3 x 6mm machine screws. Switch board There are just three switches and two header strips on the switch board – see Fig.8. Install the three switches first, taking care to ensure that the flat side of each switch is oriented correctly. The 3-pin and 4-pin header strips can then be installed. siliconchip.com.au 1 8-pin DIL IC socket (cut to make a 4-way SIL socket and a 3-way SIL socket) 1 18-pin DIL IC socket 4 9mm M3 tapped Nylon spacers 8 M3 x 6mm screws 1 M3 x 10mm screw 1 M3 nut 4 No.4 x 6mm self-tapping screws 1 80mm length of 0.7mm tinned copper wire 1 500mm length of medium-duty hookup wire 1 30mm length of 1.5mm heatshrink tubing 10 PC stakes Photo Interrupter Detector 1 PC board, code 04108083, 50 x 25mm 1 photo-interruptor (Jaycar ZD1901 or equivalent) 1 150W 0.25W resistor 1 3.5mm stereo jack plug 2 M3 x 6mm screws 2 M3 nuts 3 PC stakes 1 1m length of 2-core shielded cable IR Reflector Amplifier Capacitors 1 470mF 16V low-ESR electrolytic 3 100mF 16V PC electrolytic 1 10mF 16V PC electrolytic 5 100nF MKT polyester 1 1nF MKT polyester 2 27pF ceramic 1 PC board, coded 04108084, 53 x 32mm 1 plastic utility box, 82 x 53 x 31mm 4 M3 tapped 6mm Nylon spacers 4 M3 x 12mm countersunk screws 4 M3 nuts 1 LM358 dual op amp (IC2) 1 infrared photodiode (IR SENS1) 1 infrared LED (IR LED1) 2 100mF 16V PC electrolytic capacitors 1 10mF 16V PC electrolytic capacitor 1 1m length of twin-core shielded cable 1 cable gland to suit 3mm cable 1 3.5mm stereo PC-mount jack socket 3 PC stakes Resistors (0.25W, 1%) 1 10kW 1 39W 5W 2 1kW 1 10W 2 220W 1 2.2W Resistors (0.25W, 1%) 1 470kW 2 1kW 2 100kW 2 150W 1 10kW Semiconductors 1 PIC16F88-I/P microcontroller programmed with 0410808A. hex(IC1) 1 7805 5V 3-terminal regulator (REG1) 1 BC337 NPN transistor (Q1) 1 1N4004 1A diode (D1) 1 16V 1W zener diode (ZD1) Both headers are mounted on the copper side of the board. In each case, the longer pins of the header are first pushed into their mounting holes so that they sit about 1mm above the top of the board. That done, solder the pins to the board pads, then slide the plastic spacer along the pins towards the PC board, so that it rests against the soldered joints – see photo. Once the assembly is finished, the assembled switch board can be plugged into the main board. Fitting the LCD header The next step in the assembly is to fit a 14-pin DIL header to the lefthand end of the LCD module. As before, this header is installed from the underside of the module. Before soldering the header pins, you first have to adjust the plastic spacer so that the pins will protrude exactly 8mm below the module’s PC board. This is done by simply placing the pins on a flat surface and then sliding the spacer along them in one direction or the other so that the pin length below the spacer is about 5.5mm (the spacer thickness is 2.5mm). Once this adjustment has been made, the header can be installed from the underside and the pins soldered to the pads on the top of the module. August 2008  71 Specifications Generator Mode RPM Range: 1 RPM (0.0166Hz) to 65,535 RPM or 1092Hz Accuracy: within 1 RPM at 17,000 RPM, 1.33 RPM at 20,000 RPM Adjustment: 100 RPM coarse steps with separate 1 RPM fine adjustment over a 100 RPM range Display: both RPM and Hz Display Resolution: 1 RPM and 0.01Hz Flash Period: adjustable from 32ms to 6.50ms in 25.4ms steps or adjustable from 1-10% of period Display Update Period: 200ms Triggered Mode A larger-than-life size view of the 1W white LED. It is wired using a 1.5m length of shielded 2-core cable. Solder the red wire to the positive terminal and the white wire to the negative terminal and cut the shield wire off short. RPM Range: 1 RPM (0.0166Hz) to 65,535 RPM (1029Hz) recommended maximum Don’t plug the LCD module in at this stage though. Accuracy: within 1 RPM at 17,000 RPM, 1.33 RPM at 20,000 RPM Voltage checks Display: both RPM and Hz Display Resolution: 1 RPM and 0.01Hz Flash period: adjustable from 32ms to 6.50ms in 25.4ms steps, or adjustable from 1-10% of period Display Update Period: 200ms but can be slower for measurements below 300 RPM (5Hz) and with averaging. Division Ratios: 0.5, 1, 2, 3, 4, 5, 6, 7 & 8 Flash Position: can be shifted to any pulse edge or edge number when the division ratio is 2 or more Averaging: from 1-10 measurements for measurements over 300 RPM, reducing in number at lower RPM Trigger Edge: rising or falling (user selectable) Flash Period: setting can be either fixed or automatic Before applying power, check that IC1 is out of its socket and that the LCD module is unplugged. That done, temporarily wire in power switch S4, apply power and check for 5V between pins 14 & 5 of IC1’s socket. If this is correct, switch off, remove the switch and install both IC1 and the LCD module. Note that there is a tab beneath the LCD module (bottom, centre) that needs to be bent flat against the module’s PC board, so that it clears IC1. Secure the LCD module in place using four M3 x 6mm screws. Flash Delay From Triggered Edge To Flash: 8.75ms Preparing the case Reflective Trigger Range: 65mm for off-white plastic, 95mm for white paper If you are buying a complete kit, the case will probably be supplied pre-drilled and with screen-printed lettering. If not, then you will have to drill the holes yourself. The first step is to drill two 6mm holes in the side of the case to provide access to DC sockets CON2 & CON3. These holes should be located 9mm down from the top of the base and 17mm and 27mm in from the outside front edge. Next, drill another 6mm hole in the other end of the case for CON1. This hole must be positioned 13mm down from the top and 29mm in from the outside top-front edge of the case. The PC board can then be fitted in place and secured on the integral standoffs using No.4 self-tapping screws. Now for the lid. Fig.10 shows the full-size artwork for the lid and this can be attached to the inside of the lid SILICON CHIP POWER ON STROBE ON LED STROBE & TACHOMETER TRIGGER IN DC IN FREQUENCY (FINE ADJ) STROBE OUT MODE DOWN UP Fig.10: this full-size artwork can be used as a drilling template for the front panel. 72  Silicon Chip siliconchip.com.au The connecting cable is secured to the back of the 1W white LED assembly using silicone sealant. Silicone sealant is also used to secure the collimator lens inside the front assembly of the torch. and used as a drilling template. You can either photocopy the artwork in the magazine or you can download and print out the artwork from the SILICON CHIP website. All holes in the lid should initially be drilled using a small pilot drill, then carefully enlarged to size using a tapered reamer. Switches S1-S3 require 10mm holes, S4 & S5 require 5mm holes and VR1’s shaft requires a 7mm hole. Once the holes have been drilled, fit switches S4 & S5 and wire them to the PC board. It’s a good idea to fit heatshrink tubing over these connections, to prevent the wires from breaking (hint: push the heatshrink tubing over the switch wires before soldering the connections, then slide the tubing into place and shrink it down). The assembly of the main unit is now complete. Now let’s build the strobe unit. Testing Strobe construction The first step here is to apply power and adjust VR2 for best contrast on the LCD. The display should show a reading of between 1000 RPM and 1100 RPM on the top line and 16.66Hz on the bottom line. The Mode should be GEN. If this checks out, attach the lid and mounting brackets to the case using the four screws supplied. Now check that the RPM value can be adjusted over a 100 RPM range using potentiometer VR1. Similarly, the UP and DOWN switches should change the reading in 100 RPM steps. The default flash period is set to automatic at 5% in generator mode. In the triggered mode, the defaults are: edge is rising, division is 1, flash period is automatic at 5% and averaging takes place over two measurements. As shown in the photo above, the 1W white LED for the strobe is housed in a small plastic torch housing. The original reflector inside the torch was removed and the LED and its associated collimator lens placed just behind the front torch lens. Depending on the torch, the reflector may be easy to remove or it may be integrated with the screw thread that secures the front assembly to the torch body. In the latter case, the reflector can be removed by cutting around its perimeter using a hobby knife. The 1W white LED is wired using a 1.5m-length of shielded 2-core cable. Connect the red wire to the positive LED terminal, the white wire to the negative terminal and cut the shield wire off short. Once it’s wired, secure this lead to the back of the LED as- siliconchip.com.au The 1W white LED is then clipped into the collimator lens and secured using additional silicone sealant. This is the completed strobe assembly. A knot tied in the cable (or a cable tie) will prevent the cable from being pulled out through the end cap. sembly using silicone sealant. Silicone sealant is also used to secure the collimator lens to the front lens assembly of the torch. Once it’s in place, leave it to cure for several hours, then clip the LED assembly to the back of the collimator lens and secure it using additional silicone sealant. Leave this assembly to cure overnight. Once the silicone has cured, feed the lead from the LED through a hole drilled the rear end-cap of the torch. Use a cable tie or tie a knot in the wire to prevent the wire being pulled out of the end of the torch when the end-cap is refitted. The far end of the cable is fitted with a 2.5mm DC plug. Connect the red (positive) lead to the centre pin of the plug and the white (negative) lead to the earth terminal. That’s all we have space for this month. Next month, we’ll show you how to build the IR Reflector Amplifier and Photo-Interruptor boards and SC describe how the unit is used. August 2008  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/ DSP Musicolour: calibrating and operating PT.3: By MAURO GRASSI In last month’s article, we detailed the construction of the DSP Musicolour. In this month’s article, we guide you through the final testing of the DSP Musicolour and give troubleshooting tips. We also explain the operation of the firmware in more detail as well as discussing possible accessories. W hile the circuit of the DSP Musicolour (published in June) may at first seem complicated, it is relatively simple when you consider all the features that we have been able to pack into this powerhouse. Check out the list opposite. We think you’ll agree! We assume that you have read the first and second parts of the article in the previous two issues of SILICON CHIP. If you have followed the construction in last month’s issue, you should have a fully assembled DSP Musicolour in its case and you should have tested the supply rails at test points TP0 and TP1. These should have measured close to their correct values of +5V and +10V respectively. If they do not measure close to these values, you should refer to the troubleshooting section below for further hints, although we mentioned some extra checks to perform in that case in last month’s issue, to which you should refer first. In last month’s article, we mentioned that LK4 is optional 78  Silicon Chip and is normally omitted. When LK4 is omitted, the DSP Musicolour has three independent audio inputs which can be used to modulate the output channels. These are the Microphone input, the Left Audio channel and the Right Audio Channel. The Left and Right Audio channels from the speaker terminals on the back panel are attenuated by the LEFT and RIGHT potentiometers on the front panel. The Microphone line input is a mix of the on-board electret microphone signal and any external microphone connected to the 6.5mm jack on the back panel. When LK4 is installed, however, the Left and Right Audio channels from the back panel are mixed in hardware before being digitised by the microcontroller. In this case, either the LEFT or RIGHT potentiometer can be used to attenuate the input signal before it is digitised (and you should not install both potentiometers). siliconchip.com.au POTENTIOMETERS FFT AMPLITUDES & EQUALISATION OP AMP AUDIO CHANNEL INPUTS OP AMP MIC INPUT DIGITISING AND SOFTWARE MIXING LOGICAL OUTPUT CHANNEL LEVELS SET PHYSICAL OUTPUT CHANNEL LEVELS SET OP AMP Fig.1: block diagram of the DSP Musicolour. Use this in conjunction with the text to understand operation, programming and calibration. In other words, when LK4 is installed you lose one independent audio channel but you need only one potentiometer on the front panel. LK4 therefore controls whether the DSP Musicolour Left and Right audio channels are mixed in hardware or software (Dual mono or joint stereo). The most common option is to omit LK4 and to disable hardware mixing. With regards to the jumper links LK5 and LK6, we mentioned in the first part of the article that the default is to have LK5 installed and LK6 omitted. In fact, the firmware will ignore the state of links LK5 and LK6 – it does not matter if they are installed or not. Power up First, make sure that the plastic case has been screwed shut. When you first apply power, you should see the start up screen scroll past on the dot matrix LED display. The DSP Musicolour will go through a number of tests and then go to its default state. If you do not, you should switch off mains power immediately and go to the Troubleshooting section below. Boot-Up sequence When the DSP Musicolour first boots up, it goes through a number of internal checks before commencing operation. The following occurs on boot up (in chronological order): 1. The firmware displays the start up screen and its version number (this can be disabled for a quicker boot by changing the start up settings in the SYSTEM>Startup sub-menu). 2. The firmware measures the frequency of the mains supply. If the measured value is within tolerance, the firmware accepts the measured value and assigns its internal settings for either 50Hz or 60Hz operation (the firmware chooses the value closest to the measured frequency). If the measured value is not within tolerance, the firmware will display a warning indicating that no mains was detected and will default to 60Hz operation. In normal mains powered operation, this warning should never be seen. If it is, it indicates a problem with the Musicolour’s zero crossing detection system. The fallback value of 60Hz was chosen because it is the safer value for the purpose of controlling the Triacs in the output stages. siliconchip.com.au TRIGGER OUTPUT LEVELS FROM FFT SYSTEM CHASER PROGRAM VIRTUAL MACHINE OUTPUT LEVELS FROM CHASER PROGRAM DSP MUSICOLOUR FEATURES 1. Selectable 8-band equaliser 2. Auto detection of mains frequenc y (50Hz or 60Hz) 3. Selectable phase-controlled or zero voltage-switched output channels (8-bit resolution) 4. For each logical output channel: (a) Selectable gain (b) Selectable audio passband : arbitrary minimum and maximum frequencies (c) Selectable acquisition mod e: peak or average (d) Selectable quiescent level (filament preheat) (e) Selectable zero voltage mod e, strobe mode, direct mode or continuous mode 5. Selectable logical channel for each physical output channel 6. Chaser modes implemented as a virtual machine 7. Trigger channel with: (a) Selectable audio passband (b) Selectable trigger threshol d 8. Firmware support for RC5 remote control (requires additional PC board; to be described next month) 9. Firmware support for high speed UART (requires additional PC board) 10. Selectable balance 11. Selectable display frequency, brig htness and screen saver time-out period 12. Selectable sampling frequency from 16kHz to 50kHz simultaneous on all channels 13. Real time 7-bit FFT using double buffering 14. Persistent software settings and multiple non-volatile user memories 15. Self calibration and Diagnostics 16. Automatic and manual tuning of the internal fast RC oscillator for increased accuracy 17. Adaptive potentiometer controls 18. Silence detection and triggering 19. Input op amp stage clipping dete ction August 2008  79 3. If you are running from a 50Hz supply and somehow the frequency is not properly detected and defaults to 60Hz, the shorter mains period will at worst mean that less power is delivered to the output loads. Therefore even if your mains supply is 50Hz and the detection fails, at least the outputs will not flicker. Flickering can occur when the Triacs are switched on beyond the next zero crossing of the mains waveform and should not occur in normal operation. Another fail-safe feature is that in the rare event that no good mains frequency is detected, the firmware will disable all output channels (the rest of the firmware will function normally, however); 4. The firmware will load any persistent settings from the last active session and initialise all internal peripherals, including enabling all interrupts in the correct sequence; 5. The firmware will detect and enable any connected accessories. It is possible to add a small infrared remote control PC board to the main board to allow the DSP Musicolour to be operated by a standard RC5 remote control. Also, the firmware implements a RTSP (Run Time Self Programming) server in a secure part of program memory (it also switches the interrupt vectors to an alternative location), which can be used with a UART. The DSP Musicolour is highly customisable but for most applications you will not need to change any settings, as the preloaded defaults should be adequate. 6. The firmware will jump to the main loop (described below). Automatic Calibration Although the DSP Musicolour will adjust its settings according to the detected mains frequency, all its calculations assume a fixed system clock. The system clock is derived from the microcontroller’s (dsPIC30F4011) internal fast RC oscillator (nominally 7.37MHz) and a 16xPLL multiplication stage is used to achieve around 30MIPs operation (4 clocks per instruction). Since this oscillator’s frequency tolerance can be relatively high due to internal manufacturing variations, it may be necessary, if you are experiencing unusual effects like flickering lights on the output channels, to calibrate the frequency as close to 7.37MHz as possible. This is a good thing to do just in case. The dsPIC30F4011 has an internal non-volatile calibration setting to achieve this, meaning the internal fast RC oscillator can be tuned to bring it as close as possible to its intended frequency. The firmware assumes that the mains line frequency is very close to its theoretical value of either 50Hz (if you are in Australia, Europe and most other parts of the world) or 60Hz (if you are in America, Japan and a few other places). Since the mains frequency can be measured by the firmware against the system clock, the firmware can then calculate the error in the internal fast RC oscillator and automatically adjust it to minimise the error. This is what the firmware does in its automatic calibration. It will run once when you first power up but if you need to, you can also do it manually. To do this, go to the ADVANCED>Calibration sub-menu. If you wish to see how far from the ideal the microcontroller is operating, go to the INFORMATION>Error menu and the current percentage error in the measure mains frequency will be displayed. The Main Loop After boot up, the firmware spends most of its time in the main loop, whereby the Musicolour is either in Automatic mode (AUTO LED is lit) or User Mode (USER LED is lit). Either way, the AUTO LED or the USER LED will flash if there is no input signal detected. The SET LED will also flash if there is clipping (overload) in the op-amp stages of either the Left or Right audio input channels. While clipping is very undesirable in an audio amplifier, greatly affecting the sound quality, its effect may actually help in getting a good display from the DSP Musicolour. So the detection of clipping is merely an indication that you may want to turn down the LEFT and RIGHT potentiometers. While in the main loop, you may enter the menu system by pressing the SET button. The display is refreshed according to the currently selected display. The selected display can be scrolled to the next available display using the AUTO button when already in Automatic Mode and the USER button when already in User Mode. Some of the implemented main loop displays are shown in Table 1. Note that they do not affect the internal operation of the DSP Musicolour; they only affect what the display shows. In the main loop in Automatic Mode, the CH1-CH4 LEDs will light according to the logical output channel levels. The main difference between Automatic mode and User Mode is that in Automatic mode the Musicolour uses its current settings for all functions, whereas in User Mode, one of four previously stored settings profiles is used instead. Thus User Mode can be used to quickly run the Musicolour in a previously set configuration. In User Mode, the CH1-CH4 LEDs will indicate one of the four preset profiles currently active. You may press the CH1-CH4 buttons to Table 1: The display modes in the main loop Spectrum Fine: The spectrum is displayed on the display from lowest to highest frequency (left to right). Spectrum Centered: The spectrum is displayed in centred mode. Logical Channel Displayed Single: The output levels of each channel are displayed. The top horizontal bar indicates the first logical channel’s level. The third horizontal bar from the top indicates the second logical channel’s level. Similarly, the fifth and seventh horizontal bars from the top indicate the third and fourth logical channels’ levels respectively. Logical Channel Display Averaging: Same as above except every horizontal bar in between the output channel bars is the average of the previous and next bars. RMS display: Displays the RMS level of the input signal as an analog meter. 80  Silicon Chip siliconchip.com.au change the preset on the fly while in User Mode. The main loop running in Automatic or User Mode consists of the following sequence, which is diagrammatically represented in Fig.1. Logical and physical channels We should first mention that the firmware supports four logical output channels and four physical output channels. The physical output channels correspond to the outputs on the back panel. Each of these can be associated to a logical channel. In normal operation, the physical channel N is associated to the logical channel N. However, added effects can be achieved by changing the mapping from output channels to logical channels. For example, you can have all four physical channels on the back panel controlled by one logical output channel. We now explain the operation of the main loop. As can be seen in Fig.1, the three inputs consisting of the Left and Right audio inputs and the Microphone inputs are digitised and mixed according to the balance settings under AUDIO>Balance. Any combination of these three channels can be used as the input signal. The result of this software mixing is passed to the FFT (Fast Fourier Transform) system. The output of the FFT resolves the captured slice of the input audio waveform into 128 (27) frequency amplitudes. These are equally spaced from 0Hz up to the sampling frequency. The smallest frequency that the FFT can resolve is F/128, where F is the sampling frequency. For example, when F is 48kHz we can resolve down to 375Hz or ±137Hz. If you are not very interested in the audio sub-band above, say, 10kHz, then you can lower the sampling frequency to 20kHz and the FFT will be able to resolve frequency components down to 156Hz or ±78Hz. The audible spectrum for humans is nominally from about 20Hz to 20kHz. Although the sampling frequency of the ADC system can be set anywhere from 16kHz up to 50kHz, keep in mind that according to the Nyquist sampling theorem the highest frequency that can be resolved using a sampling frequency F is F/2. This means that aliasing will occur at least somewhere in the audible spectrum if the ADC system’s sampling frequency is set below about 44kHz. Aliasing is usually an unwanted characteristic of a digitising system. However, since most music has very little high harmonic content, in fact little content above 4kHz, it may be desirable to lower the sampling frequency in order to increase the resolution of the FFT. The FFT system computes logical output channel levels in two acquisition modes. These can be set in the CHANNELS>Mode sub-menu. The two acquisition modes are PEAK and AVERAGE. In AVERAGE mode, the average of the relevant frequency components falling within the channel’s passband (set by the minimum and maximum frequencies for the channel) will be the output level requested in the output stage. In PEAK mode, however, only the maximum level within the channel’s passband will be the output level requested in the output stage. There is an optional Equaliser module which can be enabled or disabled. The levels of the equaliser can be changed, however, by going to the AUDIO>Equaliser sub-menu. The equaliser has eight bands set to affect preset portions siliconchip.com.au Warning! The DSP Musicolour operates from the 230/240V AC mains and many internal compon ents and sections of the PC board tracks are also at mains potential. Contact with any of these could be FATAL. DO NOT TOUCH any of these parts unless the power cord is unplugged from the mains supp ly. DO NOT CONNECT this device to the mains unless it is fully enclosed in the specified case. This project is not for the inexperi enced. Do not build it unless you know exactly wha t you are doing and are completely familiar with mains wiring practices and construction techniques. of the audible spectrum. The current equaliser bands can be seen under the INFORMATION>Equaliser sub-menu and cannot be changed by the user (it can be changed by reprogramming the device however). Note that the equaliser affects the output of the FFT, not the input. After any equalisation is performed, the levels of the logical output channels are set by the FFT system, if the chaser mode is set to OFF (see the CHASER>Mode sub-menu below). If the chaser mode is not set to OFF then the level data produced by the FFT system is ignored and the data produced by the current chaser program (see the CHASER>Program sub-menu below) is used to set the logical output channel levels instead. If the chaser mode is set to TRIGGERED, then the trigger pulse (produced by the FFT system) is used to step through the chaser program. Triggering Triggering can either occur directly from the Trigger channel or from the Silence detection. Silence detection triggers when there is a relative silence in the input Left or Right audio signals (the MIC input is not used for the silence detection). The trigger can be considered a separate logical channel. It has its own selectable passband and threshold. When the threshold is reached the trigger occurs. The trigger is used by the chaser system to trigger the current chaser program in TRIGGERED mode. Tips: If, for example, you want bass response triggering a pre-set chaser program, you would set the TRIGGER minimum frequency to 0Hz and the maximum frequency to around 300Hz. Then adjust the threshold level to get an acceptable level of triggering. Light Chaser The chaser program is either executed at the rate set in OUTPUT>Output Rate or each step in the program is triggered. Both the Chaser system and the FFT system produce a set of output levels for the logical output channels. Depending on the chaser mode being used, the chaser levels or the FFT levels will be used to change the levels of the logical output channels. These will then affect the physical output channels. Channel Modes and Settings Each of the four logical output channels can operate in one of four primary modes: DIRECT mode, CONTINUOUS August 2008  81 Mode, ZV Mode or STROBE mode. In the DIRECT and CONTINUOUS modes, the brightness of the logical output channel is varied in 256 levels (8 bit resolution). The output brightness is approximately linear as the firmware uses an internal dimming curve to correct the non-linearity inherent in phase control. The difference between DIRECT and CONTINUOUS mode is how the output level is set by the output system. The main difference between the DIRECT and CONTINUOUS modes is that while in DIRECT mode the brightness is set directly, in CONTINUOUS mode, the brightness is “continuously” modified from the current brightness level. In other words, in CONTINUOUS mode, if the requested level is higher than the current level, the current level is increased by the ATTACK setting for the channel, while if the requested level is lower than the current level, the current level is decreased by the DECAY setting for the channel. Setting different ATTACK and DECAY levels for the channel can affect the level of the output logical channels in CONTINUOUS mode. In ZV Mode, the output channel responds as in DIRECT and CONTINUOUS modes, except that the output is not a brightness level but a digital output. The output is either fully on or fully off. This mode approximates a zero voltage switching mode and can be used to reduce RF interference or achieve a digital effect. In STROBE Mode, the output level sets the frequency of the logical output channel rather than the brightness level. The strobe frequency will be set from the maximum (equal to the mains supply frequency, either 50Hz or 60Hz, down to 1/256th of the mains supply frequency, ie. around 0.2Hz). Quiescent Level or Filament Preheat In all channel modes except STROBE, each logical output channel has a settable quiescent level, which is used to reduce the stress on the filaments in your incandescent lamps and to reduce surge currents through the Triacs at switch on. The quiescent level can be set by going to OUTPUT> Fig.2: one of the physical output channels being switched without software correction for asymmetrical phases. The yellow trace is the output of the Triac while the green trace is the trigger pulse applied to the gate through the optocouplers. 82  Silicon Chip Quiescent Level and is settable from 0 to 25% of the full brightness level. Note that if the channel mode is ZV (zero voltage switching) and the Quiescent Level is not 0% the channel may seem to be continuously on, depending on the ZV threshold. In this case, you should set the Quiescent Level to 0% or disable ZV mode or change the ZV threshold by going to OUTPUT>ZV Threshold. A closer look at the operation of the Musicolour The Triacs are controlled through the optocouplers using the four output compare channels of IC1 (dsPIC30F4011). In order to maintain a constant brightness of the output lights, it is necessary for the switch-on pulses to the Triacs to be synchronised to the frequency of the mains supply. To achieve this, the microcontroller uses the INT0 external interrupt pin which is supplied by one side of the transformer’s secondary winding. An interrupt can be triggered on a rising or falling edge of INT0. Now a low level on INT0 is any voltage lower than about 1.5V while a high level is considered to be anything above 3.5V. We have a 5V supply but a 7.5V secondary winding. This means that the triggers to INT0 (which is the microcontroller’s zero detection interrupt) are asymmetrical. The measured duty cycle is about 42% rather than the expected 50%. The firmware corrects this asymmetry, adjusting the value of a phase counter to take account of this. Compare Fig.2. (Without software correction) and Fig.3 (with software correction). In the scope screen grab of Fig.3, the yellow trace is the output of the Triac and the green trace is the trigger pulse. You can see that the trigger pulse period is only 8.5ms whereas for symmetrical triggering it should be close to 10ms (this is the 100Hz rate which is twice the mains frequency in Australia) as shown in Fig.3. User Operation of the DSP Musicolour The Musicolour has many settings which can be changed by the user. As mentioned, the preloaded default values should be adequate for most applications. You can go to Fig. 3: the same set up as in Fig.2 but with software correction. The period is now much closer to the correct value of 10ms. The firmware automatically corrects this asymmetry when driving the Triacs. It does so in real time at a frequency twice the mains line frequency. siliconchip.com.au the SILICON CHIP website and download more complete user instructions for the DSP Musicolour that were too long to include here. Front Panel There are seven push buttons on the front panel which are used to navigate through the menus and change internal settings. Some buttons have multiple functions, according to context. The SELECT potentiometer is also context-sensitive and is used to change settings. The incorporated LEDs in each of the buttons will light depending on the context. Usually, a lit or flashing button will mean that the button has an active function in the current menu. When the firmware is executing the main loop, the LEDs will indicate the state of the output channels and the current operating mode. Adaptive Potentiometer Controls The DSP Musicolour firmware implements adaptive potentiometer controls. This means that if a setting is to be modified using the SELECT potentiometer, the setting will begin to change only when the potentiometer position first matches the current value of the setting. This gives the potentiometer a kind of memory and is used to seamlessly change internal settings depending on the current menu. Menu System The settings of the DSP Musicolour are changed through a hierarchical menu system. When the DSP Musicolour is in the main loop, pressing the SET button allows you to enter MENU mode. Keep in mind that some of the behaviour of the Musicolour is dependent on its current settings. For example, the display will be blank if the screen saver has been set to NONE and there is no key activity for the period of the screen saver timeout. Using the Chaser Modes Go to the CHASER>Mode sub-menu. Here you can choose Normal or Triggered modes. In NORMAL mode, the currently selected Chaser program is executed. In TRIGGERED mode, the currently selected Chaser program is executed but the stepping through the program depends on the trigger (affected by the music). If you are using TRIGGERED mode, you should know that the triggering will depend on the current settings for the trigger channel. Go to the TRIGGER sub-menu. There you should set the pass-band and threshold. Set the mode to OFF to run the output channels from the FFT. Once you have set the Chaser mode, you then select the Chaser Program that you wish to run by going to CHASER>Program. Conclusion As you can see, the DSP Musicolour offers an amazing repertoire of features – far too many to allow us to describe in detail here. Next month, we plan to have more information on driving the DSP Musicolour, as well as an optional PC board which gives you complete remote control. What? A lightshow with remote control? You betcha! siliconchip.com.au Quick Setup Checklist Here’s how to set up the DSP Musicolour quickly and the relevant settings that will affect its operation: 1. Set the ADC system’s sampling Frequency: go to AUDIO>Sampling Frequency. 2. Set the mixing settings for the input signal: go to AUDIO>Balance. 3. Set the minimum and maximum frequencies for each logical output channel: go to CHANNELS>Min Freq and CHANNELS>Max Freq. Alternatively go to CHANNELS>Freq to set a non-overlapping frequency mask. 4. Set the gain for each logical output channel: go to CHANNELS>Gain. 5. Set the mode for each logical output channel: go to CHANNELS>Mode. 6. Set the output connections of the logical channels: go to OUTPUT>Logical Channels. 7. Set the CHASER>Mode and CHASER>Program 8. Exit the menu system. Tip: Every submenu has a Default option to reset all values in that submenu to default values. Simple Setup Guide Assuming you have a music source connected to an audio amplifier, connect the output terminals of your amplifier to the speaker terminals on the back panel of the DSP Musicolour. Next, adjust the sensitivity of the Left and Right channels using the LEFT and RIGHT potentiometers on the front panel. Load default values by going to the menu. Press SET while in the main loop to be directed to the menu. Scroll down to the DEFAULTS sub-menu using the UP and DOWN buttons on the front panel. Press SET to enter the DEFAULTS sub-menu. Scroll down to “Load Defaults” and press SET. This will restore all default values. Exit the menu system by pressing CH 4/D (the back button while in menu mode) and the DSP Musicolour should start running the main loop in Automatic mode. The output channels will respond to the music. Remember that the DSP Musicolour has many user options. As a summary you should know that: (a) Each of the four physical output channels must be connected to a logical channel. Two physical channels can be connected to the same logical channel. Go to OUTPUTS>Logical Channels to set these. (b) The input signal source is an arbitrary mix of the Microphone, Left and Right audio inputs. You set this in the AUDIO>Balance sub-menu. (c) The inputs are sampled at the set Sampling Frequency. Go to AUDIO>Sampling Frequency to set this. (d) For each logical channel, you should select its pass-band (the minimum and maximum frequencies). Only frequencies in the input signal that fall in this pass-band will affect that logical channel. (e) For each logical channel, you can select the gain. The higher the gain the more sensitive the channel will be to pass-band frequencies in the input signal. (f) For each logical channel, you should select its mode. This affects how the channel responds to level requests. Choose from PEAK or AVERAGE acquisition modes. These determine how the FFT data affects the level of the logical output channel. This level is interpreted differently according to the whether the channel is in DIRECT, CONTINUOUS, ZV or STROBE mode. So you should choose one of these 4 modes as well. August 2008  83 User Operating Instructions: Menu System The Musicolour uses a hierarchichal menu system. From the main loop press the SET button to enter the menu system. You will be directed to the main menu, where you may scroll up or down between sub-menus by using the UP and DOWN buttons. Use the SET button to enter a sub-menu. In any submenu, you may use the CH4/D button to go back to the previous menu (if you are in the main menu, you will be directed back to the main loop). Sub-menus available in the main menu: 1. CHANNELS: this sub-menu allows you to change any settings related to the four logical channels; 2. TRIGGER: this sub-menu allows you to change the trigger passband and the trigger threshold; 3. CONSOLE: this sub-menu contains user applications, allowing the Musicolour to function as a light dimmer or communications terminal; 4. OUTPUT: this sub-menu is used to set the chaser mode, the chaser program, the output rate, the quiescent level of each physical channel and to define the logical to physical channel translation; 5. AUDIO: this sub-menu is used to change the equaliser settings, the software mixing/ balance of the input signal and the sampling frequency; 6. DEFAULTS: this sub-menu is used to save and recall settings and to load default values; 7. ADVANCED: this sub-menu is used to access advanced features, including calibration, software upgrade and tuning; 8. INFORMATION: this sub-menu displays information about the Musicolour’s operation like the mains frequency, the frequency of the ADC system and the screen refresh frequency. The error in the overall accuracy of the timing system can also be seen; 9. DISPLAY: this sub-menu is used to change the display’s settings, including the screen refresh frequency, the screen brightness and the screen saver time out period; 10. SYSTEM: this sub-menu can be used to change system settings, the firmware version is displayed, the baud rate of the UART can be changed, the remote control system can be enabled and other system settings changed; Here are the major sub-menus used at this stage: CHANNEL submenus: CHANNELS>Min Freq: Press the channel buttons CH1-CH4 to display the current minimum frequency for that logical channel; Use the SELECT potentiometer to change 84  Silicon Chip the minimum frequency; CHANNELS>Max Freq: Press the channel buttons CH1-CH4 to display the current maximum frequency for that logical channel; Use the SELECT potentiometer to change the maximum frequency; CHANNELS>Freq: this is similar to the CHANNELS>Mi n Freq menu, except that after exiting, the minimum and maximum frequencies for the four channels are set in non-overlapped fashion. CHANNELS>Gain: Press the channel buttons CH1-CH4 to display the current gain for that logical channel; Use the SELECT potentiometer to change the gain. CHANNELS>Mode: Press the channel buttons CH1-CH4 to display the current mode for that logical channel; Use the UP and DOWN buttons to scroll through the available modes; CHANNELS>Attack: Press the channel buttons CH1-CH4 to display the current attack rate for that logical channel; This is only relevant when the channel is operating in CONTINUOUS mode. Use the SELECT potentiometer to change the attack rate. CHANNELS>Decay: Press the channel buttons CH1-CH4 to display the current decay rate for that logical channel; This is only relevant when the channel is operating in CONTINUOUS mode. Use the SELECT potentiometer to change the decay rate. CHANNELS>Test Channel: Press the channel buttons CH1-CH4 to test the relevant logical channel with a range of output level requests from 0 to full level; This can be used to test the current settings for the channel. CHANNELS>Defaults: Press SET to restore default CHANNEL sub-menu values; TRIGGER sub-menus TRIGGER>Min Freq: Press the UP and DOWN buttons to set the minimum frequency defining the trigger pass-band. Exit using the SET button. TRIGGER>Max Freq: Press the UP and DOWN buttons to set the maximum frequency defining the trigger pass-band. Exit using the SET button. TRIGGER>Threshold: Use the SELECT potentiometer to change the threshold level for the trigger. Triggering will occur when the input signal has an amplitude component within the trigger pass-band that is greater than the trigger threshold. The level is indicated as a horizontal bar. Exit using the SET button. TRIGGER>Defaults: Press SET to restore default TRIGGER sub-menu values. CONSOLE sub-menus: CONSOLE>Dimmer: Press the channel buttons CH1-CH4 to select the relevant logical output channel. Use the SELECT potentiometer to change the output level of this channel. Here the Musicolour functions as a four channel light dimmer. CONSOLE>Com: The Musicolour enters an echo terminal mode. Received data from the UART is displayed on the display. The UART can be enabled using additional hardware. OUTPUT sub-menus: OUTPUT>Chaser Mode: the current chaser mode is displayed. Press the SET button to scroll to the next available mode. OUTPUT>Chaser Program: the current chaser program is displayed. Press the UP and DOWN buttons to set the program. Press SET to exit. OUTPUT>Output Rate: the current output rate is displayed. Use the SELECT potentiometer to change the rate; Press SET to exit. OUTPUT>Quiescent Level: Press the channel buttons CH1-CH4 to select the relevant logical output channel. Use the SELECT potentiometer to change the quiescent level of this channel. OUTPUT>Logical Channels: Press the channel buttons CH1-CH4 to select the relevant physical output channel (on the back panel). Use the UP and DOWN buttons to change the logical output channel associated to that physical channel. In Normal operation, you set CH1=1, CH2=2, CH3=3, CH4=4; if for example, you wish to have logical channel CH1 control two physical outputs on the back panel you could set CH1=1 CH2=1 CH3=3 CH4=4; If you would like to permute the channels you can also do that here. OUTPUT>Defaults: Press SET to restore default OUTPUT sub-menu values. AUDIO sub-menus: siliconchip.com.au AUDIO>Equalizer: The current equalizer settings are shown as vertical bars. Use the UP and DOWN buttons to scroll to the next setting, and use the SELECT potentiometer to vary the current equalizer setting. AUDIO>Balance: the current percentages of each the three audio channels contributing to the input signal are shown. Press SET to change these. The levels are then displayed as bars. The first bar from the left is the MIC line level. The next two bars indicate the LEFT and RIGHT levels respectively. Use the SELECT potentiometer to change the LEFT/RIGHT balance. Use the UP and DOWN buttons to change the MIC contribution to the input signal. AUDIO>Sampling Frequency: the current sampling frequency in kHz is displayed. Press SET and use the SELECT potentiometer to vary this value. AUDIO>Defaults: Press SET to restore default AUDIO sub-menu values. DEFAULTS sub-menus: DEFAULTS>Load Defaults: Press SET to restore all settings to default values; DEFAULTS>Save Settings: Press UP and DOWN buttons to change the memory number to save to. Press SET to save all current settings to non volatile memory. DEFAULTS>Recall Settings: Press UP and DOWN buttons to change the memory number to load values from. Press SET to load all settings with previously stored values. ADVANCED sub-menus ADVANCED>Calibration: Press SET to automatically calibrate the Musicolour’s internal fast RC oscillator against the mains frequency. ADVANCED>Software Upgrade: Press SET to upgrade the firmware. This mode requires a functioning UART connecti on, which needs additional hardware. ADVANCED>Tune Oscillator: Press UP and DOWN to change the internal calibrating value for the system clock. This value is updated by the automatic calibration above. You can manually adjust the value here. INFORMATION sub-menus There are no settings to change here. Only the values of certain system parameters are displayed. This is for operating information like the mains frequency, the screen refresh rate, the sampling frequency, the system clock, the error in the system timing from the ideal, etc. DISPLAY sub-menus: DISPLAY>Brightness: Press SET to change, us- siliconchip.com.au ing the SELECT potentiometer, the brightness of the display. SYSTEM>Reset: Press SET to reset the Musicolour. DISPLAY>Frequency: Press SET to change, using the SELECT potentiometer, the screen refresh frequency. Note that strange display effects can occur at low screen refresh frequencies. If this is the case, increase the frequency. Usually a level around 65Hz or higher is adequate. SYSTEM>System Defaults: Press SET to load SYSTEM submenu defaults. DISPLAY>Timeout: Press SET and use the UP and DOWN buttons to select the timeout period for the screen saver. DISPLAY>Screen Saver: Press SET and use the UP and DOWN buttons to select the current screen saver. DISPLAY>Display Defaults: Press SET to restore all DISPLAY submenu defaults; SYSTEM sub-menus: SYSTEM>Version: displays the current firmware version. SYSTEM>Uart: Press UP and DOWN to change the baud rate for the UART. This requires additional hardware. SYSTEM>Remote Control: Press SET to enable or disable the remote control decoding. This requires additional hardware and can be used to control the Musicolour using an RC5 compatible remote control. SYSTEM>IrDA: Press SET to enable or disable the IrDA decoding. This requires additional hardware and can be used to add a wireless infrared serial port. This can be used to send and receive data from a PC. SYSTEM>Test: Press SET to run a test on the display, the output channels and the LEDs. Can be used to check that all these are working correctly. SYSTEM>Detected Mains: this shows the detected mains frequency and is either 50Hz or 60Hz. It should match your area’s mains supply frequency. SYSTEM>Startup: Press SET to scroll through the start up modes for the Musicolour. The initial startup can be made quicker by disabling the normal boot-up messages. SYSTEM>RF6: Press UP and DOWN to change the RF6 pin mode. This is an advanced feature that can be useful to debug any problems with the Musicolour. The RF6 output of the microcontroller is a digital output and is available at pin 9 of CON3 on the main board. The system clock frequency can be measured at this pin, as well many other internal operating frequencies like the screen refresh frequency and the ADC system frequency. You will not need to normally use this menu. In Depth Explanation of the Main Loop In more detail the main loop is as follows: 1. The firmware waits until the internal ADC system signals that the buffer has been filled with digitized and software mixed audio data (while waiting all interrupts are active, including all timers, key press detection and display refresh interrupts); 2. Once a full buffer of data has been acquired, the Fourier Transform is computed; 3. For each logical output channel, a level corresponding to the channel is computed. This may involve adjusting the output of the FFT with equalization, it will depend, for each channel on its selected acquisition mode; 4. A request is made, for each logical output channel to set its output level to the previously computed level. The implementation of this step is dependent on the channel’s current setting. If a channel should be accepting data from an active chaser program, the level requested in this step is ignored; 5. If a Chaser program is active, it is serviced by the virtual machine; This may involve the triggering channel if the program is in trigger mode; Any output level requests made by the chaser program are set. Again, the implementation of this step is dependent on the channel’s current settings; 6. The display is refreshed according to the currently selected display: 1. Spectrum Fine: the spectrum is displayed on the display; 2. Spectrum Centered: the spectrum is display in centered mode; 3. Logical Channel Displayed Single: the output levels of each channel are displayed. The top horizontal bar indicates the first logical channel. The third horizontal bar from the top indicates the second logical channel. Similarly, the fifth and seventh horizontal bars from the top indicate the third and fourth logical channels respectively. 4. Logical Channel Display Averaging: same as 3. above except every horizontal bar in between the output channel bars is the average of the previous and next bars. 5. RMS display: displays the RMS level of the input signal as an analog meter. 6. The firmware updates any LEDs on the front panel and returns to step 1. It also responds to key presses. August 2008  85 FRO NT SEC ON DARY 100 nF E NIL N OITAL OSI ISO LATION 220 Ω 220 Ω 220 Ω PIN 3: 4.7k 0V 100 nF 10k 100 k + 5.6nF 10k 10k 10k CON 2 1k 47 µF IC2 LM3 24 4148 PIN 5: +5V DC 220 Ω 270 Ω 1W + 1k 470 Ω 100 nF dsPIC 30F4 011 IC1 + Problem: You apply power and there is a sudden short of the mains supply (consequently the fuse blows or the circuit breakers/ fuse in your home open). There seems to be a short of the mains supply. Possible Cause: This could be caused by incorrect link settings for LK1, LK2 and LK3 underneath the mains transformer. first” mode If all goes to plan, you’ll bui ld the DSP Musicolour, turn it on . . . and1kit will work per TRANSFO RM ER fectly, first time. But what if it doesn’t? 4148 D8 100 Ω + We’ve warned a number of TP0 470 times tha t the Musicolour must not be run with the lid µF off and the ma TPI ins connected. It is simply too dangerous. D11 So how can you work on an unpowered circuit? D12 LED8 T1 Obviously, you can’t. But D13 fortunately, all of the log 30V D14 icA 7.5 V and processing circuitry (inc luding the dsPIC) can be run from a 5V DC supply (ra ted at 500mA or so) so you can troubleshoot with safety 4700µF . If you need to poke around 16V the Musicolour, CON3 can LK5 LK6 be used to supply pow er to the100 circ Ω uit. Simply +5V to pin 5 and 0V to pin 100con Ω nect 3 of CON3 and all of 100the Ω lowvoltage circuitry will be pow 1 µF ered, up to and including the D10 fou r opto-couplers. DON’T plu g in D9 the mains lead! 1k Problem: You apply power and there seems to be no activity, there is no display. Possible Cause: Is the fuse blown? Have you installed a fuse? 8 0 0 2/ 4 0 G M RU OL O CISU M Troubleshooting in “safety YRAD N O CES Some common problems that may help you troubleshoot the DSP Musicolour. 1 8 0 7 0 1 0 1 CS REG 1 LM3 17T CON 1 4148 Troubleshooting Tips: TNORF + 33k 33k 3.3k OPTION AL Problem: 9 1 Section + 270 Ω 1W 10 2 One or both voltages at test points TP0 and TP1 are not at LINK 47 µF of full MIC normal levels around +5V and +10V respectively. 270 Ω 1W overlay Possible Cause: from the CON 3 68nF 68nF 68nF One possible cause is that links LK1, LK2, LK3 are impropJuly 2008 68nF erly set or omitted. Remember these have to be installed SILICON CHIP according to the mains supply voltage. Install LK2 and omit LK1 and LK3 if you are using a 220-240V mains supply; install LK1 and LK3 and omit LK2 if you are using a 110-120V mains supply. These links are found under the mains transformer, so you may have to unsolder the transformer to change them. If you have erroneously configured these links for 110-120V operation while you are actually in a 220-240V region of the world, you will get double the intended voltage at test-point TP1. This can very easily destroy REG1 and cause further damage to the main PC board. Disconnect power immediately if the voltages at TP0 or TP1 are much higher than their intended values. Problem: The main board seems to be operating correctly, except nothing is shown on the dot matrix LED display. Possible Cause: The most common cause of this problem is that the 26-way ribbon cable connecting the main board and the display board is either faulty, not all connections are good, or it is incorrectly oriented. If you can verify that the ribbon cable’s 26 connectors are good, it may indicate a fault with incorrectly oriented parts. Check the transistors and ICs are correctly oriented on the display PC board. Check also that the dot matrix LED modules are in their sockets the right way around. Problem: At least one key does not respond to key presses or its LED does not light up. Possible Cause: This is most likely caused by the tactile switch being incorrectly oriented, improperly soldered, or its accompanying diode being incorrectly oriented. Problem When in a menu, moving the SELECT potentiometer does not affect the setting, or does so after much turning. Possible Cause: This is most likely not a problem but a feature. It is called adaptive control. See the text for an explanation. Tips and Tweaks Notice that if the display frequency is set too low you may see strange effects on the display. Increase the screen refresh frequency if this occurs. Also, if the sampling frequency is lower than twice the highest frequency of the input audio, aliasing will occur. 86  Silicon Chip siliconchip.com.au OPTO 1 MOC 30 What About the Musicolour Display – ie, the Lights! The DSP Musicolour is capable of driving up to 2400W of lights over its four channels, with a maximum of 800W in any one channel. That’s an awful lot of coloured light – far more than you’d normally find at a party, which tend to be on the dark side anyway. Let’s look at the type of lights you can use (and shouldn’t use). First of all, steer clear of halogen (QI) lights. Their problem is the time the filament takes to cool and the light to go “out”. They also get very hot and this can be a problem with coloured films – depending on the type, they scorch with high temperatures and can even catch fire. That’s about the last thing you want. By far the most popular display/party lights are the coloured ES (Edison screw) PAR38 or R80 bulbs. The coloured PAR38s are usually rated at 120W (their plain white cousins are usually 150W, some 120W). Incidentally, just in case you wanted to know, PAR38 means Parabolic Aluminised Reflector, 38 eights of an inch (or 4.75 inches) in diameter. R80 means an 80mm diameter reflector light globe. So there! The biggest problem with coloured light globes is the price – they are rather significantly more expensive (like about four times or more!) than white. But I have a sneaky solution here: paint white globes and save heaps! You can’t use ordinary paint, of course – it is opaque. But you can buy translucent glass paint at better craft stores in a wide variety of colours. The most usual colours for light displays are also the easiest to get – red, yellow, blue and green. This paint is intended for making (fake!) “stained glass” windows but I’ve found it to be quite tolerant of high temperatures so can be painted directly onto white globes. The brand I use is Vitrail, from France. But I’ve also seen other brands of this type of paint advertised on eBay (just make sure it is translucent/transparent when dry!). I’ve used it for years instead of buying coloured globes and it works very well. You simply paint it on so that the glass has an even covering; usually only one coat is required. Allow it to dry before turning on the light – even then, you’re likely to get some coloured vapours given off and it does tend siliconchip.com.au to stink a little! If I’m in a real hurry, I might apply a little heat from the light globe – say ten seconds on, a minute off – to impart a little forced drying. OK, so that’s the coloured globe side covered. Now, how about their mounting? Simple, I thought: just go and buy some ES batten lampholders, mount them on a length of flat timber and wire them up. Yeah, simple all right: have you seen the price of ES battens recently? You can get standard BC (Bayonet Cap) batten lampholder for about $3-$5 just about anywhere. The same things in ES (Edison Screw), which are required for the PAR38 and many R80 bulbs, tend to start at around $13-$14 and go up from there. (Why?!!) But I cheated here, too. In our local Bunnings Hardware store, I spotted a PIR movement detector security light, complete with two ES lampholders and two 150W PAR38 bulbs, all for just $15.95. So I bought two of these, giving me four ES lampholders and four PAR38 bulbs for just over thirty bucks! I discarded the two PIR sensors (anyone know what to do with two brand new PIR sensors?) and mounted the two sets of two ES lampholders on the length of flat timber and wired them (individually) to short 240V mains leads. Even here I was able to save, by using old 240V leads. Call it the scrounger in me if you will but every time I discard any electric appliance, if the mains lead is OK I cut it off and save it – just in case. Well, here’s the case and phhhhttt to all those who have criticised me for hoarding rubbish saving and recycling perfectly good stuff! In fact, I used two such salvaged mains leads and two old IEC mains leads, which had also been saved from the scrapheap (actually By Ross Tester rescued from the last council clean-up). The IEC plugs themselves were not needed (not now, at least!) so I cut them off with maybe 250mm of mains lead attached (just in case!) and put them back in my “spare mains lead” box. You never know. . . That gave me four mains leads, complete with three-pin plugs, about 1.5m long. Perfect! I’ve shown a photo of my el-cheapo Lamp Display Unit above. While this is very obviously only one approach, it gives you an idea of what you can do to make a very reasonable lightshow for a very reasonable price. The ES bases even have some very handy terminal blocks inside so wiring them up is delightfully easy. Each light operates completely independently to any other so all are wired separately. Remove the wires from the PIR unit and discard it. Connect the active (red or brown wire) in one of your mains leads to the white wire going to the lampholder, the neutral (black or blue) to the blue wire and the earth (green/green yellow) to the green/yellow wire in the terminal block. Repeat for the second mains lead and ES base, then fasten the mains leads under the anchor strip provided (there is just room). Screw the assembly onto a suitable piece of timber. Put the top on, screw it all up and put your two PAR38 bulbs into their holders. Connect both mains plugs to a suitable outlet to ensure both lights work. Repeat all this for the other ES base assembly, check it – and you’re ready to plug it into your DSP Musicolour and light up your life. Oh, you did remember you SC had to build the Musicolour first? August 2008  87 Vintage Radio By RODNEY CHAMPNESS, VK3UG The incredible 1925 RCA 26 portable superhet receiver portables was not particularly difficult at the time. By contrast, designing a workable superheterodyne receiver wasn’t particularly easy in 1925, as the valves that were then available were not very suitable for the task of frequency conversion. In fact, the design could be quite critical if the set was to operate at all. That situation improved in the early 1930s with the development of the 2A7 and similar converter type valves. These new valves proved to be quite tolerant of circuit design inadequacies, making the design and manufacture of superhet receivers much easier. The RCA 26 portable superhet receiver with its front open, ready for use. Prior to the 1930s, virtually all domestic broadcast receivers used TRF circuits. One exception was the 1925 RCA 26 portable which was one of the very first domestic superhets. It used some truly innovative technology for the era. U NTIL RECENTLY, I’d always thought that “portable” radios (if you could call them that) were an innovation of the mid to late 1930s. However, at the HRSA’s 25th Anniversary celebrations last year, I was amazed when I saw Mike Osborne’s 1925 RCA 26 portable. Not only is it a fully-working concern but it also uses a superheterodyne circuit. 88  Silicon Chip Why was this so remarkable? Well, superheterodyne receivers didn’t become common in Australia until the mid-1930s. This means that, at the time, this set was a truly innovative design that was at the leading edge of technology. The RCA 26 was also one of the earliest, commercially-made portable radios, although manufacturing Superhet principles Before the 1930s, most sets employed TRF (tuned radio frequency) circuits. However, these had their shortcomings and superhet designs quickly took over when suitable valves became available. The superhet (or superheterodyne) principle was developed during World War 1 by Major Edwin Armstrong of the US Army. Armstrong was a prolific radio inventor who also developed other radio techniques, including regeneration, super regeneration and frequency modulation (FM). Basically, the superhet was developed because during WW1, the allies needed direction finding (DF) receivers that could receive the extremely weak spark transmissions used by the Germans in Europe. Apparently, tuned radio frequency (TRF) receivers could not be made sensitive enough or stable enough for this task, so an alternative technique had to be found. In operation, a TRF receiver tunes siliconchip.com.au and amplifies the incoming RF (radio frequency) signal at the frequency of interest and then presents the amplified signal to the detector. This then feeds an audio amplifier stage which boosts the audio signal to headphone or speaker levels. Although this had the benefit of simplicity, there were a few problems with TRF sets which limited their usefulness. The first was that they had to be capable of accurately tuning the incoming RF signal across a wide range of frequencies. In the early days, this was achieved by adjusting several tuning capacitors or variometers to obtain the best reception, as ganged capacitors were not available. In some sets, this could involve up to four or even five adjustments. In addition, some detectors require a certain minimum level of signal for them to work effectively. This meant that, in some cases, additional RF gain was needed. Unfortunately, this is difficult to achieve with a TRF set due to problems with feedback between the various stages. During the early 1920s, triodes were almost exclusively used to amplify both RF and audio signals. However, at RF, triodes must be “neutralised” in order to achieve reasonable gain and stability. This “neutralisation” involves adding an extra capacitor to cancel out the grid-to-plate capacitance inherent in each triode RF stage, to prevent it from oscillating. In addition, triodes were not good at amplifying frequencies above 500kHz, again due to inter-electrode capacitance and also due to lead inductance. Even in those very early days of radio, the TRF failed to meet the “state of the art” needs of the military during WW1. By contrast, in a superheterodyne receiver, the RF stage (or stages) provides only moderate amplification, which allows easier tuning and greater stability. This also means that there is less need for significant shielding between stages. The amplified RF signal is then applied to a converter (or mixer) stage where is mixed with a signal from a local oscillator stage. In an AM broadcast receiver, this local oscillator stage typically operates at a frequency that’s 455kHz (or thereabouts) higher than the tuned RF signal. siliconchip.com.au Another view of the 26 receiver, this time with the access covers removed for the valves (top) and the reflexed horn speaker. The loop antenna was housed in the hinged section attached to the front cover. As a result, the output from the mixer stage consists of four separate frequencies: (1) the original tuned signal frequency; (2) the signal frequency plus the local oscillator frequency; (3) the local oscillator minus the signal frequency; and (4) the local oscillator frequency. Lets’s take a look at an example to illustrate this; If the tuned frequency is (say) 1000kHz (1MHz), then the local oscillator will run at 1455kHz (ie, 455kHz higher). As a result, the mixing frequencies will be 1000kHz + 1455kHz = 2455kHz and 1455kHz - 1000kHz = 455kHz. This means that the following frequencies will appear at the plate of the converter valve: 455kHz, 1000kHz, 1455kHz & 2455kHz. These signals are all fed to the following intermediate frequency (IF) stage but since this stage is tuned to 455kHz, only this frequency is passed on for amplification. It does, however, contain all the audio information that was included with the original signal frequency. Because the IF amplifiers and the RF amplifiers are on different frequencies, they do not inter-react with one another. Because of this, significant gain can be achieved in the IF amplifier and so the overall gain can be quite high. In addition, the IF stages amplify only a narrow band of frequencies and because these are usually lower than the signal frequencies, amplification is easier to achieve. Initially, in the 1920s, an IF of 100kHz was used, then a very low IF centring on 25kHz was used followed a little later by 55kHz. In fact, this latter IF is used in the RCA 26 portable. At such low frequencies, most triodes didn’t need any neutralisation. In addition, the gain of the UV99 RF valve used in the RCA receiver is only 6.6 under optimum conditions, so the IF stages in the 26 were not neutralised. Following the IF stages, the signal was fed to the detector and the IF component removed. The resulting audio signal was then fed to the audio amplifier. Audio amplifier stages are generally easier to design than RF amplifiers. Most of the triodes of the 1910s and early 1920s were quite stable at audio frequencies but the gain of individual UV99 triodes was quite low (6.6). As a result, to achieve a higher gain per stage, inter-stage audio transformers were used. These generally had step-up turns ratios somewhere between 3:1 and 5:1, which could boost the gain of a UV99 stage up to a maximum of 30 times. However, these audio transformers had a very limited frequency response, as well as having peaks and troughs in the response. On the other hand, a 6AV6 with simAugust 2008  89 would be just 10kHz on either side of 100kHz. In fact, it was the low “Q” factor of early tuned circuits and the meagre amplification of signals above 500kHz by the triodes of the era that dictated the use of low intermediate frequencies in early superhets. Overcoming the problems The view shows the chassis after it has been removed from the cabinet. The valves are easily accessible so that they can be replaced while most the rest of the circuitry is sealed in the “catacomb box” (or sealed container) at the right, to prevent users fiddling with the adjustments. ple resistance/capacitance coupling will easily exceed this figure, with amplification of up to 70 times per stage. It will also have a much improved bandwidth and no nasty peaks and troughs across the frequency band. Early superhet problems Unfortunately, despite their clear advantages, early superhets also had their problems. However, these were quickly overcome by Edwin Armstrong and other designers of the era. One early problem involved the large 60-100cm tuned-loop antennas that were commonly fitted to receivers from the 1920s to the early 1930s. Initially, the superhets had a converter stage connected to the loop antenna and a separate local oscillator was coupled into the loop. The following IF section then had up to five stages of amplification. However, with this arrangement, it was found that the local oscillator radiated signals via the loop antenna and this was picked up as interference (in the form of whistles) by nearby receivers. In addition, the action of tuning 90  Silicon Chip the loop (or even someone walking near it) caused the oscillator to change frequency, so much so sometimes that the wanted signal was shifted out of the pass-band of the IF amplifier. This effect was particularly evident as the loop and the oscillator were tuned to frequencies quite close to one another. Another problem with early super­ hets was that one tuned circuit could lock onto the frequency of another stage with a higher “Q” factor. “Q” refers to a tuned circuit’s “quality factor” and is a measure of the “sharpness” or selectivity of the tuning response. A circuit with a Q of 100 is much more selective than one with a Q of 10. As an example, let’s assume a circuit with a resonant frequency of 1000kHz and a Q of 10. In this case, the response at 950kHz and 1050kHz will be half that at 1000kHz, ie, the response will be 3dB down at the +50kHz and -50kHz points. Or to put it another way, the circuit has a -3dB bandwidth of 100kHz. However, at a tuned frequency of 100kHz, the -3dB bandwidth points Oscillator radiation from the loop antenna was overcome by adding a neutralised triode RF amplifier between the loop and the converter stage. In addition, the RF stage and the converter were coupled using an untuned RF transformer and this overcame much of the pulling of the oscillator by the RF tuned circuits. It was also found that running the oscillator at half the received signal frequency plus or minus the intermediate frequency, also substantially reduced oscillator pulling. So how did the circuit work if the oscillator ran at half the required frequency. The answer was quite simple – the second harmonic of the oscillator was used to heterodyne with the received signal to give the IF. Having solved most of the problems of producing a usable superhet receiver, the designers found that no less than eight valves were required to build it. However, an 8-valve set, even one using low-current valves, had a higher current drain than was practical to expect dry batteries to supply. In fact, the first superhet receivers used 201 valves which draw 1A each at 5V, thus giving a total current consumption of 8A. This meant that the very early designs could not be used as portables. At that stage, a superhet receiver used a neutralised triode RF stage (V1) which was coupled to a triode mixer/ converter stage (V2). The signal was then mixed with the heterodyning signal from a separate local oscillator (V3). The output from the converter then fed two IF stages (V4, V5) and these in turn were coupled to a grid leak detector (V6). This then fed two transformercoupled audio stages (V7, V8), with the amplified audio signal then going to a speaker or to headphones. In order to produce a portable set, it was necessary to find some way of reducing the current drain. That meant reducing the number of valves while still maintaining good performance. Two techniques were available to siliconchip.com.au RCA’s 26 portable receiver RCA’s 26 portable receiver uses this same 6-valve design technique. In fact, this set is one of several variants built by RCA at the time and their circuits are almost identical – see Fig.1. However, some of the features shown on the circuit are not included in the 26, while some of the features of the 26 do not appear on other variants. For example SW1, SW2 and J1 are not fitted to the 26. The 26 is switched off by turning the battery rheostat (R3) fully anti-clockwise, so SW1 was not needed. In addition, the loudspeaker is wired permanently to V6 so the use of headphones is not an option. The 26 uses UV99 valves in all six valve sockets. This valve is designed for a filament voltage of 3-3.3V and a filament current of 60-63mA. As a result, the receiver draws approxisiliconchip.com.au Fig.1: the RCA 26 is an early superhet receiver employing a reflexed RF stage (V1) and an autodyne (or self-oscillating) mixer stage based on V2. In operation, the reflexed RF stage functioned as both an RF stage and as the first IF stage. V3 is the second IF stage, V4 is the detector and V5 & V6 are the audio stages. achieve this: (1) reflexing and (2) using a self-oscillating mixer. Last month, we looked at how reflexing was achieved in the Astor KM receiver. However, in those early days of superhet receivers, the technique was applied in a slightly different way. The RF amplifier stage amplified the incoming signal, which then went to the mixer. The resulting IF signal was then fed back into the RF stage again which now acted as the first IF stage. Its output was then applied to the second IF amplifier. Basically, it was possible to use the RF stage to handle both RF and IF signals because the signals were at a low level. In addition, the difference between the IF frequency (25-55kHz) and the signal frequency (520kHz or more) meant that there was minimal interaction between the two. Initially, the mixer and local oscillator stages required two separate valves. However, this was subsequently reduced to just one valve when the designers came up with the self-oscillating mixer. In other words, one valve functioned as both the mixer and the oscillator and this stage became known as an “autodyne mixer”. It was seldom used during the later valve era but was commonly used in transistorised receivers. Thus, by using a reflexed RF stage and an autodyne mixer stage, the designers were able to reduce the valve count from eight to six. This not only reduced the current drain but saved on expensive valves as well. August 2008  91 The large reflexed horn speaker sits behind a panel in the bottom of the cabinet. of the photo). However, for home use, a larger battery pack was normally used to power the set. The 26 receiver has the usual frame (loop) antenna but provision was also made to connect a larger loop antenna and to connect long-wire antennas. This tuned circuit feeds valve V1 which functions as a combined RF and first IF amplifier stage. This stage is neutralised using trimmer capacitor C6. V1’s output is coupled via an aperiodic (untuned) RF transformer to V2, the self-oscillating mixer. The oscillator’s tuned circuit consists of L9, L10 and C2. The resulting IF signal is fed through L9, L2, L1b & L1a to the grid of V1 where it is amplified and fed via L3 the second IF transformer (L5 & L6). V3 is the second IF amplifier and its output feeds grid detector stage V4 (via L7, L8 & C8). The audio from this stage is then applied via transformer T1 to audio amplifier stage V5. Note that in some sets (but not the 26), V5’s output is either fed via switch SW2 to a set of headphones or fed to audio output stage V6 via transformer T2. A reflexed horn speaker is fitted into the bottom of the receiver case (see photo) and this is driven by V6. The efficiency of these speakers is quite high, so the very low output from the UV99 is perfectly adequate for normal listening. Tuning This compartment at the rear of the set was used to house batteries for portable use (the owner’s modern rechargeable battery pack is shown here). However, a larger external battery was generally used to power the set for use at home. mately 370mA from the three seriesconnected No.6 cells that are used in the portable configuration. Adjustable resistor R3 is used to set the filament voltage applied to the valves and this must not exceed 3.3V. Note that if eight valves had been used, the filament current drain would have been 500mA. In addition to the filament current, valve data books indicate that a UV99 92  Silicon Chip valve will draw 2.5mA with a bias of -4.5V and a 90V plate supply. With all valves drawing the maximum current, the HT (high-tension) drain will be no more than 15mA, which can easily be handled by a relatively small HT battery pack. One of the accompanying photos shows where the batteries sit for portable use (Mike’s modern, rechargeable battery pack can be seen in the centre The receiver is tuned using separate local oscillator and RF controls on the front panel. We rarely experience “double-spotting” or image reception in modern broadcast receivers but radios like the 26 allow the same station to be heard on at least two other spots on the broadcast band, this in addition to the intended position. This is due to the very low IF used (approximately 55kHz) and also due to the use of the oscillator’s second harmonic to produce this IF. As previously indicated, R3 is used to adjust the filament voltage. It could be adjusted so that the valves still received around 3V even with almost flat batteries. R2 is the volume control and operates by varying the filament voltage applied to valve V3. This rather crude method of volume control was used on many early radios. No form of AVC (or AGC) is employed on this receiver siliconchip.com.au This plaque attached to the back of the set shows the patent information relating to RCA’s Radiola 26. and in fact, this feature didn’t become common on radio receivers until the 1930s. Access to the valves is obtained by removing a metal cover near the top of the set. The loop antenna is mounted on the front lid of the receiver and once the lid is opened, the loop can be swivelled for best performance. The antenna loop is terminated on a 4-terminal strip – see Fig.1. Fig.1 also shows two sets of “A” batteries, as used for the larger home battery pack. In addition, the receiver used four 22.5V B batteries to supply 90V of HT to all valves except the grid-leak detector (V4). The main workings of the receiver are enclosed in a sealed box section called the “catacomb”. This section of the receiver is shown within the dotted lines of Fig.1. The valve sockets are mounted on the front face of the catacomb and the valves are the only components shown within the dottedline enclosure that are actually outside the shielded box. Apparently, early superhet receivers This adjacent label gave advice on battery use. A lead fitted with a jack plug selected the battery pack. were difficult to service and the sealed container was designed to stop people from fiddling with the adjustments of this rather critical circuit. Prior to the introduction of superhets, experimenters and serviceman were only used to TRF receivers and so might have been tempted to experiment with the adjustments in the absence of a cover. As shown in Fig.1, there are a couple of coils with the comment “dead end” on them in the circuit. The purpose of these coils is unclear, although they may have been some form of neutralisation system for the IF stages. No external antenna Early superhet sets were popular with people who did not want to take out a radio listener’s licence, as no external antenna was necessary (which meant they could avoid detection). However, they were not used in Australia for many years, mainly because they were so advanced for their time that fault-finding proved difficult for service people, who generally only understood TRF technology. In addition, there were problems for non-technical users such as double-spotting and extraneous whistles. AWA did make superhets from 1925-1927 but then stopped and made nothing but TRF receivers until 1933. It would appear that they found the early superhets just too advanced for the average serviceman to effectively maintain. The early AWA designs were very similar to the RCA “catacomb” designs. However, there were a few variations such as the use of anode-bend detectors and regeneration on the RF stage (called an “intensifier”). Their 1927 models used L410 or P410 valves in the audio output stage. Summary The RCA 26 was a remarkable receiver for its time. Even today, it performs remarkably well, with quite good sensitivity, although doublespotting and other extraneous whistles and noises are quite obvious. This is a set well worthwhile having in a SC vintage radio collection. into MICROS OR PICS? There’s There’s asomething reference to to suit suit every every microcontroller maestro in the SILICON CHIP reference bookshop: see the bookshop pages in this issue Microcontroller Projects in C – by Dogan Ibrahim Graded projects introduce microelectronics, the 8051 and $ 8100 programming in C. 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 $ 8050 and MPLAB SIM. Hands-On ZigBee – by Fred Eady An in-depth look at the clever little 2.4GHz wireless ZigBee chip that’s now being found in a wide range $ equipment from 9650 of consumer to industrial. PIC in Practice – by DW Smith Ideal introduction to PICs. Based on popular short courses for the PIC for professionals, techs, hobbyists, $ 60 students and teachers. PIC Microcontroller – know it all ( Newnes) Newnes have put together the best of subjects their authors have written on over the past few years $ 7995 into this one handy volume! The PIC Micro – personal intro course – by John Morton A very practical guide which assumes no prior knowledge. So it is an introduction to the widely$ 52 ideal used PIC micro. ! Audio ! RF ! Digital ! Analog ! TV ! Video ! Power Control ! Motors ! Robots ! Drives ! Op Amps ! Satellite siliconchip.com.au August 2008  93 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 ilicon Chip Use your PayPal account www.siliconchip. Call (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 Place94  S 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 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 Use your PayPal account www.siliconchip. Call (02) 2008  95 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 August 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 PRODUCT SHOWCASE Low-cost video and still capture recorder from Tenrod Tenrod has just released their latest Digital Video Recorder module, the DVR623. This low-cost module comes complete with wired camera and keyboard to make a convenient start-up system. It is an easy-to-operate, automatic and low-cost video and still capture recorder, able to detect movement via the camera, enabling automatic video recording or still capture. At the same time, it can provide a live output to a TV monitor from its video‑ camera. It also has an alarm output which can be utilised to alert an operator, trigger an alarm or activate other functions. The module, supplied without enclosure, needs only a single DC power source to operate. Image size is VGA or QVGA, with a variable frame rate setting of 1, 10 and 30 fps. Recording duration can be set from 1-99 seconds. Small 4-inch TFT colour LCD screens are also available for use in conjunction as a small portable monitor. Contact: Tenrod Australia Pty Ltd 1/24 Vore Street, Silverwater, NSW 2128 Tel: (02) 9748 0655 Fax: (02) 9748 0258 Website: www.tenrod.com.au Voice Activated Universal Remote Control Want to add voice-activated remote control – to just about anything? This amazing device allows you to control anything that has a remote control with voice commands. No matter if it’s your TV, Stereo, Set-top Box or even air conditioner, now you can control them all without even lifting a finger. Simply set up your voice command and then press the appropriate buttons on your original remote control, the voice activated controller will then “learn” the signals and reproduce them whenever you trigger it with your voice command. Up to ten signals can be transmitted with one voice command. Contact: MicrogramAustralia Pty Ltd PO Box 8202, Tumbi Umbi, NSW 2261 Tel: 1800 625 777 Fax: (02) 4389 0234 Website: www.mgram.com.au Microcontroller Development Boards Arduino is an open-source microcontroller development board and environment based on the ATMega168 AVR microcontroller family and a simple programming language based on C++. They are available from Ocean Controls in Victoria. The Arduino Diecimila USB is ready to be programmed using a USB port, without the need for a separate hardware programmer. The Arduino-compatible Skinny board shrinks the design by separating the programmer from the board and provides a smaller, cheaper alternative. The Arduino LilyPad is like the Skinny, but is designed to be wearable e-textile technology by making it washable and incorporating large connecting pads to allow it to be sewn to clothing with conductive thread. A starter kit and 96  Silicon Chip many sensor boards are available as well. There are free and easyto-learn programming tools compatible with Windows, Mac and Linux, and boards starting from $27.50 + GST. Contact: Ocean Controls 3/24 Wise Avenue, Seaford, Vic 3198 Tel: (03) 9782 5882 Fax: (03) 9782 5517 Website: www.oceancontrols.com.au Superb L-C Meter Kit Altronics have sent us their version of the SILICON CHIP L-C meter (June 2008) . . . and we have to say we’re very impressed! They’ve gone for a professional instrument-style case – it’s larger and flatter than the zippy box we used but certainly “feels” more instrument-ish, with terminals at the top and the display on the front. Otherwise, the kit follows the original design. The kit (Cat K2533), which is available from Altronics stores and dealers, has a retail price of $84.95. Contact: Altronics Distributors Pty Ltd 174 Rowe Street, Perth, WA 6000 Tel: 1300 797 007 Fax:1300 789 777 Website: www.altronics.com.au ANTRIM TRANSFORMERS manufactured in Australia by Harbuch Electronics Pty Ltd harbuch<at>optusnet.com.au Toroidal – Conventional Transformers Power – Audio – Valve – ‘Specials’ Medical – Isolated – Stepup/down Encased Power Supplies Toroidal General Construction OUTER INSULATION OUTER WINDING WINDING INSULATION INNER WINDING CORE CORE INSULATION Comprehensive data available: www.harbuch.com.au Harbuch Electronics Pty Ltd 9/40 Leighton Pl, HORNSBY 2077 Ph (02) 9476 5854 Fax (02) 9476 3231 siliconchip.com.au 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 silchip<at>siliconchip.com.au Garage door indicator wanted Do you know of a circuit that tells me if my garage door is up or down? I want this done wirelessly, so a simple magnetic reed switch on the garage door sends a wireless signal to a receiver inside the house (say up to 20m) such that if the door is up, a LED lights up. (B. C., via email). • We published a Garage Door Indicator in the January 2007 issue. If you want to run the receiver section from a 9V battery instead of the specified 12V plugpack, you can omit the 7809 3-terminal regulator, change the two 680W resistors to 1.5kW and change the LEDs to high brightness types. Bigger transformer is a problem I’m about to construct one of your fine Studio 350 amplifier modules (January 2004) to power a subwoofer system. Unfortunately I am finding it difficult to obtain the recommended toroidal transformer with 50V + 50V output at 500VA. Jaycar and Altronics used to stock them but now only have a 55V + 55V transformer. This will give DC voltages of around ±77V instead of ±70V. I am wondering if this will be fine with either minimal or no changes to the design. (J. W., via email). • The problems with using a 55V + 55V transformer are two-fold. First, because it gives a 10% higher supply rail, the overall dissipation of the amplifier can be expected to increase by about 21%, so it will get quite a bit hotter. This may or may not be a problem if you are using 8-ohm loudspeakers and will have an upside in that the maximum power output will also go up by about 20%, from 240W music power to about 290W. But if you are using a 4-ohm loudspeaker, much higher supply rails mean that the amplifier could be driven beyond the safe operating area (SOA) of the output transistors, as depicted in the diagram on page 14 of the article. That might mean that you blow the transistors and possibly, as a result, burn out the speaker as well. That could be extremely costly. Hence, it would be preferable if you use the specified 50V + 50V transformer. Contact Harbuch Electronics at (02) 9476 5854. They should be able to supply a suitable unit. Recommended value for reset pull-up resistor I have noticed that the pull-up resistor on the reset pin of the PIC microcontrollers varies between 1kW and 100kW, depending on the circuit. The data sheet on the 16F88 indicates a circuit with R less than 40kW. Could you please comment on this? (G. C., Mt Dandenong, Vic). • The recommended value for a pull-up resistor on the MCLR line of the PIC16F88 ranges from 1kW (to limit transient current) through to a maximum of 40kW. The value used depends a lot on the designer’s whim at the time. Typically, we prefer a value of 10kW because it provides a lower current into the MCLR pin should a transient occur or should the supply go below Vdd. The 40kW maximum is because leakage current from the pin could affect reset operation should a higher value be used. Charging problems with tank sender I recently built the telemetry version of your rain water tank level meter. It appears to be working fine, but I’m having problems with the sender unit’s power supply. The article says that it can be powered from a plugpack provided a rechargeable AA battery is present (I’m using a NiMH one). It doesn’t suggest a suitable voltage for the plugpack, so I chose the smallest I could find, 6V (switchmode, I believe). Having connected this up, I saw the Courtesy Light Delay for Cars I have built the ‘Courtesy Light Delay for Cars’ which worked perfectly in my previous car. I now have a different car with three internal lights which draw too much current from the light delay kit. This makes the lights stay extremely dim for the set delay time. Is there any component in the kit I could change to allow more current during the delay period? If not, would changing the lights to LEDs help or allow too much current to flow? (D. A., via email). siliconchip.com.au • The lamp current is effectively set by the on-resistance of the Mosfet and this is initially set to a low value to switch on the lamps fully. The dimming is due to the resistance of the Mosfet increasing as its gate voltage decreases over time. At switch-on the Mosfet should be low resistance and the lamps should light fully regardless whether there are three lights or one. You may be able to increase the effective brightness of the lamps by increasing the C1 value to 1000µF. This would give more gate voltage at switch-on. Also increasing R2 to 470kW may help increase the initial gate voltage. If you use LED lights, then a 100W 5W resistor would have to be placed across the courtesy light circuit in place of the original lamps to provide the circuit supply current. LED lighting tends to have several LEDs in series plus a current limiting resistance and so there is too little voltage for the circuit to work without this extra resistor. August 2008  97 Making Relay Selector More Flexible I found a “Circuit Notebook” item in the January 2006 issue that will be useful for me. It is a pushbutton relay selector. I was wondering if someone could leak the identity of IC1 to me. I promise I’ll keep it a secret. Is there a way this circuit could be modified so that it does not trip one relay off before activating the next (ie, to give the option of multiple ‘lives’? (D. M., Camden, NSW). • As shown on the circuit diagram to which you refer, IC1 is a 4093B quad CMOS Schmitt NAND gate. In order to modify this circuit to allow more than one relay to be activated at a time, you’d need to use diodes (eg, 1N4148) to gate the relay voltage displayed on the LCD of the reader unit climb to somewhere over 1.5V. However, at some point after that the voltage began to drop until the sender was no longer able to communicate with the reader unit. I then checked the plugpack output with a multimeter and found that it was producing only about 0.7V with no load. Has the sender unit destroyed the plugpack? Replacing the NiMH battery with an alkaline one made the sender unit operational again, but I’d prefer to not have to change the battery. I’m also not particularly keen to use a solar panel because the tank is a fair way from natural light. Any suggestions would be appreciated. (J. B. Umina Beach, NSW). • The Schottky diode D2 must be replaced with a 1kW resistor as mentioned in the article. The plugpack can be any voltage from 3V to 12V. If the cell does not stay charged, then the charge current is not sufficient. A lower resistor value may be required. Typically you need about 1/10th of the full charging current for the cell, as listed on the cell itself. Calculate the current by subtracting 1.25V from the plugpack voltage and dividing by the resistor value. A 6V plugpack with a 1kW limiting resistor should charge at about 4.8mA. IR decoding for slave flash I have constructed the digital slave flash trigger from the July 2003 issue 98  Silicon Chip driver transistors from more than one output of IC2. For example, in order to have both relay 1 and relay 2 on together, you’d need to have an additional selector pushbutton switch connected between (say) IC2’s output 5 (pin 1) and pin 9 of IC1c, to create a fifth (1+2) selection setting. Then you’d also use a pair of 1N4148 diodes to connect between the O5 output of IC2 and the gates of Q1 and Q2, with a 100W resistor in series with each diode. Then when you press S6 the extra selector button, the counter will stop at the O5 position and both relay drivers Q1 and Q2 would be turned on together. but am wondering whether it can be modified for infrared transmitter operation. I have a Canon 430EX flash unit with optional slave unit function for IR control. (Y. H., via email). • It would not be possible without major modifications so that the slave trigger could decode and respond to the IR code from your flash gun. In any case, the slave flash should be directly compatible with your flash gun as it is. Noise cancelling for Kenwood Chef Mixer My wife’s Kenwood Chef mixer is very noisy. I Googled “noise” and “Kenwood Chef” in an effort to find out if having such a noisy machine is normal (it is, apparently). What I need is for someone to invent a noise-cancelling device for the Kenwood Chef. Because I am not technical I can’t do it myself but surely someone could tell me how to set up a microphone and speaker to sit next to the noisy mixer, with a noise-cancelling circuit to kill the noise! Would it work “in the open” or does the technique only work with headphones? (I guess one problem in the open might be that the microphone would also pick up the “out of phase” sound from the speaker. (T. J., Gordon, NSW). • The Kenwood Chef must be one of the noisiest kitchen appliances ever invented. Noise-cancelling does not work in the open. You need closed chamber such as in Bose headphones, the cabin of car (eg, Honda Legend) or an appliance cupboard. It would be possible to do noise-cancelling in an appliance cabinet but really, if you are using a mixer you do need to be able to open the cupboard while you use it and that action would destroy the noise-cancelling. Ultimately, we don’t think such a project is viable. We have pulled a Kenwood mixer apart to see where the noise was coming from. It is a combination of motor and gearbox noise which is exacerbated by the speed control which has a tendency to “hunt” back and forth, regardless of the speed setting. In reality, they should give away a free set of ear protectors whenever they sell this appliance! Failing that, the best approach is to shut the mixer in an appliance cabinet while it is in use. Upgrade for 3-way Active Crossover I was wondering, since you have produced the new ultra fidelity preamp and various new amplifier modules, whether there might be plans to offer an upgraded version of this 3-way Active Crossover kit featured in the January 2003 issue? The TL074 op amps featured in the circuit are now outdated. Would the new National Semiconductor LME49740 op amps drop in without any circuit modifications? If a total upgrade was planned I would like to see level controls for the various output bands available on the front panel, plus an overall input level adjustment and a buffered full range input/output loop. (D. B., via email). • We have no immediate plans to upgrade the Active 3-way Crossover. It does appear as though the LME49740 could be a direct drop-in replacement for the TL074s and is a far superior op amp. However, given the circuit configuration used, there is no guarantee that the overall noise performance and distortion would be much improved. PIC-based tank level meter has surges I have built the PIC Based Water Tank Level Meter (SILICON CHIP, November & December 2007 and January 2008). All works well in general but I siliconchip.com.au CD-ROM Playback Adaptor Fault I have recently completed a CDROM Audio Playback Adaptor kit (SILICON CHIP, November 2007) but I cannot get the LCD module to initialise properly. It merely displays a single line of 16 blocks of dot matrix patterns. The supply rails indicate the correct voltages and pins 1 & 2 on the LCD module also show +5V and 0V respectively, which I believe is correct for the Jaycar supplied module. I have tested this with three different CD-ROMs, two of them pulled from working PCs so I don’t imagine that this is a compatibility problem. I have done the usual checks of the board for broken tracks and shorts, resoldering any suspect joints etc but to no avail. Would this problem indicate that the micro supplied has not been programmed or that I have somehow accidentally erased the program or should I look elsewhere for a solution? (S. R., Hastings, Vic). • The symptoms you describe could be caused by a number of factors, including: (1) the LCD module connection to the board is not good (some of the 16 connections may be bad); (2) the microcontroller has not been programmed with the correct fuse bits; (3) the microcontroller is faulty or not programmed properly (unlikely) or (4) the LCD module is faulty (unlikely). The first item is the most likely cause of your problems, so we suggest that you double-check that all 16 connections from the board to the LCD module are actually good. If you have access to an oscilloscope, you should check the relevant lines like E (enable) at the LCD module and you should see short pulses when the microcontroller is trying to write to the LCD module. The relevance of (2) is that if the fuse bits on the microcontroller have not been programmed correctly, the microcontroller may not be running at the correct clock frequency of 7.3728MHz. If this was the case, since the LCD module you have is sensitive to small timing discrepancies, it would give the symptoms you are describing. In other words, the micro must be running at 7.3728MHz or very close to it, for the software to work correctly. Given a preprogrammed microcontroller, it is very difficult to erase it simply by handling it, so unless the microcontroller was faulty or not programmed properly then points (3) and (4) are unlikely. have a few questions. In the telemetry version I find that when I calibrate the tank level, sometimes I get sudden display surges of up to 10%. For example, when I calibrate at 85% tank level, the value transmitted and displayed remains at 85% for a while, the suddenly may jump to 94%, and after another 15 minutes or so, returns to the original, true value of 85%. I am using the shortest update interval of approximately 16 seconds. I use the version where the sensor is mounted in a separate box outside the tank, fed by a T-piece in the outflow line. I think that these surges are caused by the water pressure pump fed from the tank. But why does it then not return to 85% soon after the pump has switched off? Is there something like hysteresis or friction in the sensor? Or does the software cause this delay effect? The battery voltage shown on the receiving end is 1.3V or more, even at night. This would be about 0.1V too high. Where can I calibrate it? (K. F., Munster, WA). • The water tank level meter receiver may show a higher level for a long period because the signal from the transmission is not received reliably. So a valid signal may only occur every 15 minutes. You can check whether the receiver detects a valid signal within 16 seconds by switching off power to the receiver then switching on. The display should show the correct levels within 16s. Transmission and reception is improved using an external antenna, as discussed in the articles. Sensor hysteresis is 0.1%. The voltage across the cell could be 1.3V. Check this with a multimeter. Rechargeable cells that are charged can show 1.3V when lightly loaded. The cell readings are taken with the water level meter powered up and accuracy is set by the 5V calibration for the switchmode regulator output using VR1. There is no other adjustment since the analog to digital converter for the reading is referenced to the 5V supply. It is accurate to within about 5mV. the battery when starting the bike. I have already assembled the kit, bench tested it, set it appropriately and all works fine but I do have a question to do with the signal input. I would like to use a direct connection to the battery as the signal input. I figured this would be OK as when the bike is off, the battery outputs between 12.5 - 13.2V, whereas once the bike is actually running, the regulator increases the voltage to 14V - 15V. Will using a direct connection to the battery as a signal input be OK? I’m worried that the Universal Switch might get fried or something since the signal input is connected directly to the battery. Should I be worried about anything else if I do set it up this way? I plan to connect the ignition siliconchip.com.au Uncertainty about Voltage Switch kit I recently purchased a Universal Voltage Switch kit from Jaycar (Performance Electronics for Cars). I intend to install the switch on my motorbike, to stop the headlights from turning on until the engine has started. At the moment, they turn on automatically as soon as you put the key in and switch the bike to ‘ON’. I want to do this so that there is less strain on Ozitronics Tel: (03) 8677 1411 Fax: (03) 9011 6220 Email: sales2008<at>ozitronics.com Rolling Code 2-Channel UHF Remote K157 - $80.30 Momentary or latching relays with indicator LEDs and reset inputs. Up to 15 Tx can be linked to one Rx. 12VDC. Also available assembled: K157A - $95.70 Extra 2 and 4 button remotes also available More kits & documentation available on website: www.ozitronics.com : August 2008  99 switch +12V to an accessories wire and of course, ground the switch to the chassis. (S. S., via email). • The Voltage Switch is protected for operation from a bike battery, with zener diode ZD2 at the signal input and with zener diode ZD1 at the supply input. The unit is therefore suited to your application without danger of damage to the electronics in the circuit. LED ammeter for a genset I would like to use the LED Bargraph Ammeter (SILICON CHIP, January 1999) on a portable genset. It would need to go across a 50mV shunt and start at 0V, LED 1. What mods would be needed please? How about a project combining the above and the Battery Monitor featured in Electronics Australia in the May 1987 issue? (H. B., Wynyard, Tas). • The LED Ammeter is capable of displaying a 20A range with a 0-40mV input. The range and offset from zero is adjustable and no changes to the circuit should be necessary. There is no reason why you could not incorporate the EA display with the LED Ammeter display. MPLAB not needed for dsPIC programmer Regarding the PIC programmer project described in the May 2008 issue of SILICON CHIP, I assume it requires the MPLAB program as well as WinPic to operate. If this is the case, which of the MPLAB programs is required? (A. D., via email). • The dsPIC programmer in the May 2008 issue works with WinPIC, as described in the article. You do not need MPLAB to use it. You simply load a .hex file into WinPIC and program your PIC/dsPIC that way. The only reason you may need MPLAB is to compile your source code into a hex file. For that, almost any version (including the most current) is suitable. Trouble-shooting an ignition kit I have just completed repairing a high energy ignition kit that my son built some years ago. He blew it up accidentally by hooking it up incorrectly. I have replaced Q1 with the TO-3 package and have also replaced the MC3334 and Q3. All the other components have been checked. My problem is that Q1 stays on, regardless of the points being open or shut. I recently purchased the back issue of SILICON CHIP to help me set it up. The kit does everything as per instructions. Originally the car did not have a ballast resistor but I have since installed one. It still does not work. Do you have any idea what could be wrong? I have built the points version. (J. C., via email). • The transistor will appear to remain on with points open because this transistor only opens (goes off) for a short 0.9ms period before switching on again. This is the dwell extension feature of the ignition circuit. You can temporarily alter the circuit so that the transistor will follow the action of the points by placing a short across the C1 (0.1µF) capacitor at the collector of Q2 that passes signal through to pin 5 of IC1 via a 22kΩ resistor. If the transistor still remains on with this test, perhaps the transistor’s case Notes & Errata UV Light Box, November 2007: the 4.7kW resistor shown connected between pin 3 & 10 of IC1 is incorrect. It should be between pin 10 and +5V, as on the PC board. is shorted to the metal box or the zener diodes are shorted. Aid wanted for setting pendulum clocks I have some difficulty in setting several pendulum clocks vertical so that the pendulum beats correctly. Listening to the “tick-tock”, as advised by Mr Eckles (not a joke), the horologist to the National Trust, and adjusting the vertical position from the “tick-tock--tick-tock”, is quite difficult. Could you consider a project that would listen to the beat and display the timing and difference in the beat so that the pendulum length could also be adjusted to beat seconds? Could this project be used for other audible timing measurements? (J. H., via email). • That is really quite a specialised application so we would not do it as a project. In any case, it would be more practical to have the pendulum work with a photo-interrupter and an accurate period counter. However it would need to be very accurate, of the order of several parts per million to usefully set pendulum length for good time-keeping. As an aside, part of the charm of keeping old clocks is the trial and error process of adjusting pendulum clocks. It can take months to get it right, as you have found. SC 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. 100  Silicon Chip siliconchip.com.au 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. 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:___________________ FOR SALE TECH REPAIRS SERVICE MANUALS: www.techrepairs.org Thousands of manuals for all brands, makes and models including: Vintage Radio, PDP, LCD, VCR, DVD, CTV, Laptops, Monitors, Sewing Machines, Washing Machines, Dryers, Fridges and many more. An absolute must have website for any Tech! 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 LEDs! Nichia superbright oval LEDs and 5mm Agilent (HP) LEDs - brandname quality LEDs at Chinese LED prices! Osram surface mount range and other NOS standard and superbright brand name LEDs from just a few cents each. Cree XR-E LEDs, LED drivers, kits and other interesting stuff. www. ledsales.com.au FACTORY OUTLET: flexible neon wire. Sheet (Backlight cuttable) flower. LGP Backlight. EL products. Phone 041 771 8607 Fax (07) 3397 5787. Email: cjappliance<at>gmail.com DOWNLOAD OUR CATALOG at MicroByte Electronics: PIC Micros – Development Board – Development tools & Components. Phone: (03) 9378 4288. info<at>microbyte.com.au; www. microbyte.com.au WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au www.iinet.net.au/~worcom siliconchip.com.au 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 WANTED WANTED: A REINARTZ COIL, Aegis type M12. Please contact Nathan on (02) 9586 3017 or email me nsamuels1<at> bigpond.com KIT ASSEMBLY KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com August 2008  101 VIDEO - AUDIO - PC Degen 1103 Pocket Receiver distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates Range 100kHz - 29,999kHz, direct entry, digital display. Listen to SSB, amateur radio, marine weather, HF aircraft, shortwave and many more. Supplied with rechargeable AA batteries, approved charger, 10m longwire, carry case and earphones. $159.00 + P/H Contact Av-Comm Pty Ltd 02 9939 4377 email: michael<at>avcomm.com.au DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters MD12 Media Distribution Amplifier QUEST ® Quest AV® VGA Splitter VGS2 C O N T R O L S HQ VGA Cables faster with the world’s easiest controllers! best v alue! AWP1 A-V Wallplate Come to the specialists... You get results Do you have wireless problems? Telelink has wireless solutions! If you want the right ‘wireless’ ingredients for a successful project recipe, THINK Telelink! Don’t want to be confused by wireless gobbledegook and confusing buzz words? TALK to Telelink! We will give you honest advice so that you can make the right purchase decision for your OEM low power wireless requirements. Browse our website for more information about our products. If you have any questions speak with a Telelink Communications representative. At Telelink we sell solutions, not problems! 01010101 Telelink Communications www.telelink.com.au e-mail Jack Chomley – jack<at>telelink.com.au or call (07) 4934 0413 or 0428 199 551 ® Quest Electronics® Pty Limited abn 83 003 501 282 t/a Questronix ELNEC IC PROGRAMMERS Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au MS120OEM216 $149 1-off Developer’s Kit $193 includes programming cable & software Made in Australia - enthusiastic users world-wide www.dontronics.com has 300 selected hardware and software products available from over 40 world wide manufacturers, and authors. Olimex Development Boards & Tools: ARM, AVR, MAXQ, MSP430 and PIC. Atmel Programmers And Compilers: STK500, Codevision C, Bascom AVR, FED AVIDICY Pro, MikroElektronika Basic and Pascal, Flash File support, and boot loaders. 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Money back guarantee. www.dontronics-shop.com 102  Silicon Chip splat-sc.com ISM ISM Tx/Rx + 8051 Modules eRF-PoB. 433, 868 or 915MHz Programmable On Board Via RF Use any 8051 Assembler/Compiler Nordic Semiconductors nRF9E5 8051 Processor: 32K Eeprom: 8 I/O:SPI:RS232:16MHz XTL etc. Mini RF Programmer Development Platform 1 off Module Price $59.00 Plus GST High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP CLEVERSCOPE USB OSCILLOSCOPES 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 GRANTRONICS PTY LTD www.grantronics.com.au ellert-technologies.com.au Battery Packs & Chargers Siomar Battery Engineering www.batterybook.com Phone (08) 9302 5444 siliconchip.com.au Do You Eat, Breathe and Sleep TECHNOLOGY? Advertising Index Opportunities for full-time and part-time positions all over Australia & New Zealand Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 39 stores in Australia and New Zealand. Our aggressive expansion programme has resulted in the need for dedicated individuals to join our team to assist us in achieving our goals. We pride ourselves on the technical knowledge of our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do: Knowledge of electronics, particularly at component level. Assemble projects or kits yourself for car, computer, audio, etc. Have empathy with others who have the same interest as you. May have worked in some retail already (not obligatory). Have energy, enthusiasm and a personality that enjoys helping people. Appreciates an opportunity for future advancement. Have an eye for detail. Why not do something you love and get paid for it? Please write or email us with your details, along with your C.V. and any qualifications you may have. We pay a competitive salary, sales commissions and have great benefits like a liberal staff purchase policy. Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd P.O. Box 6424 Silverwater NSW 1811 Email: jobs<at>jaycar.com.au Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. RFMA RF Modules Australia Low Power Wireless Connectivity Specialists Applications: Parani-SD100 Laptop/PDA Bluetooth Serial Adapter OEM Bluetooth Module comms, control In Stock NOW! In Stock NOW! AT Interface & measurement. Range 100m to 1Km Rural No drivers Power: +18dBm Class 1 Industrial Range of upto 1Km Data rate: upto 115200bps Bluetooth Spec: V2.0+EDR Commercial SENA: OEM Bluetooth Modules and Serial Adapters Parani-ESD1000 RF Modules Australia. P.O. Box 1957 Launceston, TAS., 7250. Ph: 03-6331-6789. Email: sales<at>rfmodules.com.au. Web: rfmodules.com.au HIGH QUALITY VALVE/TUBE KITS MUDLARK VALVE AMP KITS THE A205 a u d i o NX-14 RETRO NIXIE CLOCK s y s t e m s IMPROVED VERSION EVEN BETTER SOUND & LOOKS SC July-Aug 2007 Kit: $899.00 Built: $1299.00 New Models The A2.1 Series Stereo Valve + Subwoofer Amp The best of SE triode sound with a built-in powerful bass subwoofer amp. Total 60W power! 3 KIT VERSIONS FROM $399.00 With genuine NOS valves. Ask for the A2.1 brochure. LIMITED PRODUCTION These amazing clocks are loved by technical and non-technical people alike. Features retro vintage Nixie tubes & crystal control for accurate time. FULL KIT: $259.00 with transparent housing & blue LED uplighting. LESS HOUSING: $199.00 GLESS AUDIO: 7 Lyonsville Ave, Preston 3072. SPK360Email: 3/5/06 1:10 PM Page 1 Phone: (03) 9442 3991   Mob: 0403 055 374   glesstron<at>msn.com The long-time supplier of PC boards to enthusiasts is finally calling it a day and needs to make arrangements to keep this valued service to readers in operation. The prospective buyer will need to be an enthusiast and also happen to have a large shed, 3-phase electricity supply and broadband internet. For more info on plant, SAV etc, contact Bob Barnes at sales<at> rcsradio.com.au siliconchip.com.au 20 years experience! HI-FISPEAKER REPAIRS YOUR EXPERT SPEAKER REPAIR SPECIALISTS 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! tel: 03 9647 7000 www.speakerbits.com PC Boards SPK360 RCS Radio Pty Ltd is FOR SALE Agilent Technologies......................... 3 Altronics..................................... 74-77 Aztronics........................................... 6 Av-Comm...................................... 102 CJ Appliance................................. 101 Computronics................................ 102 Dick Smith Electronics............... 22-23 Dontronics..................................... 102 Ecowatch...................................... 101 Ellert Technologies........................ 102 Emona Instruments........................... 7 Force Electronics.............................. 6 Front Panel Express.......................... 7 Furzy Electronics.............................. 4 Futurlec........................................... 10 Gless Audio................................... 103 Grantronics................................... 102 Harbuch Electronics........................ 96 Instant PCBs................................. 101 Jaycar............................IFC,49-56,103 JED Microprocessors........................ 5 Keith Rippon................................. 101 LED Sales..................................... 101 Microbyte Electronics.................... 101 Ocean Controls................................. 8 Ozitronics........................................ 99 Quest Electronics.......................... 102 RCS Radio.................................... 101 RF Modules...........................103,OBC Sesame Electronics...................... 101 Silicon Chip Binders........................ 57 Silicon Chip Bookshop..... 31,93,94-95 SC Perf. Electronics For Cars......... 60 Silicon Chip Subscriptions.............. 17 Siomar Battery Industries............. 102 SOS Components........................... 47 Soundlabs Group............................ 10 Speakerbits................................... 103 Splat Controls............................... 102 Tech Repairs................................. 101 Tekmark Australia.................. 104,IBC Telelink.......................................... 102 Tenrod Pty Ltd................................. 11 Truscotts Electronic World............. 101 Wagner Electronics...................... 9,45 Worldwide Elect. Components...... 101 Printed circuit boards for SILICON CHIP designs can be obtained from RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. August 2008  103                                               siliconchip.com.au 104  Silicon Chip                                                                                                                  siliconchip.com.au August 2008  105  