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siliconchip.com.au February 2013  1 BACK TO WORK DEALS A head start in building a tool kit or simply add to the existing set. Tool Box Deal 1 includes: BACK TO WORK • Duratech 25W Soldering Iron • High quality 32 Piece Precision Driver Set • 4 Tray Tool/Storage Case TS-1465 $13.95 TD-2106 HB-6302 $17.95 $16.95 Tool Box Deal 2 includes: • Set of five 115mm cutters and pliers • High quality 32 Piece Precision Driver Set • Data Hold Multimeter • 4 Tray Tool/Storage Case DEAL #2 Total value: $48.85 TH-1812 $29.95 TD-2106 $17.95 QM-1523 $14.95 HB-6302 $16.95 Total value: $79.80 5995 $ SAVE $19.85 DEAL #1 3995 $ SAVE $8.90 IP67 True RMS Cat IV DMM with Wireless USB A quality true RMS multimeter with a wireless USB computer interface and includes logging software which allows computer based live data whilst keeping your computer completely isolated and protected. $ 00 Double moulded housing and SAVE $10 IP67 rated. 99 • Autoranging • Non-contact voltage indicator, data hold • Diode test and audible continuity • Cat IV, 600V, 4000 count • 10A current range • Size: 170(L) x 79(W) x 50(H)mm QM-1571 was $109.00 10MHz Handheld Pocket Oscilloscope A complete portable oscilloscope! Aside from standard scope features, it has nifty tools for measurement of RMS speaker power, display hold function, and memory storage for 2 signals. Housed in a durable rubber surround with backlit LCD display and inbuilt Ni-MH battery. See our website or in-store for full specifications. 22900 SAVE $20 • CRO probe and USB charge cable supplied • 10MHz, rechargeable • Size: 114(H) x 74(W) x 29(D)mm QC-1914 was $249.00 Safely measure temperature in hot, hazardous, or hard to reach places with the built-in laser pointer directed at the surface. Provides several readings within seconds. Compact and easy to use with carry case included. • 8:1 Distance to spot ratio • Auto data hold • Temperature range: -30°C to +260°C • Size: 131(H) x 96(W) x 35(D)mm QM-7215 4995 $ To order call 1800 022 888 PCB not included A quick & simple bulb type solder sucker that is affordable, compact and effective. Buy two and you will always have one handy. • Size: 50(D) x 110(L)mm approx. TH-1850 Buy 2 for $8 save $5.90 695 $ PCB Holder with Magnifying Glass 59 $ 95 SAVE $10 Also available: Replacement Filters Pk.5 TS-1581 $9.95 Economy Non-Contact Thermometer • Lens: 110(Dia.)mm • Requires 3 x AAA batteries (SB-2425 $3.95) $ QM-3532 Solder Sucker & Blower Bulb Designed to remove dangerous solder fumes from the work area. It incorporates a ball bearing high volume fan to maximise airflow. Suitable for use in production lines, service centres, R&D workbenches or the hobbyist. • Mains powered • ESD safe • Size: 260(H) x 200(W) x 170(D)mm TS-1580 was $69.95 This handy hobbyist's magnifier has a 2 x main magnifier lens with 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. 2995 Solder Fume Extractor $ Illuminated Gooseneck Magnifier An extra pair of hands and eyes for those fiddly jobs. Supports PCBs while soldering etc. Features 90mm magnifying glass and two alligator clips. • Size: 78(L) x 98(W) x 145(H)mm TH-1983 1295 $ PCB not included ATTENTION KIT BUILDERS Can’t find the kit you are looking for? Try the Jaycar Kit Back Catalogue Our central warehouse keeps a quantity of older and slow-moving kits that can no longer be held in stores. A list of kits can be found on our website. Just search for “kit back catalogue”. Prices valid until 23/02/2013 www.jaycar.com.au Contents SILICON CHIP www.siliconchip.com.au Vol.26, No.2; February 2013 Features 12 Replace Your Halogen Down-lights With LEDs Got lots of 12V halogen down-lights? Is your electricity bill killing you? Maybe you should think about replacing those power hungry halogens with some efficient 10W and 13W multi-LED units – by Leo Simpson High Performance CLASSiC DAC; Pt.1– Page 22. 16 The Historic Rubicon Hydroelectric Scheme It’s not well known like the Snowy Mountains Scheme but the Rubicon Hydroelectric Scheme once supplied almost 17% of Victoria’s electricity – by Dr David Maddison 80 Review: The XR-450M UHF Handheld Transceiver It’s tiny, it’s waterproof, it’s programmable, it packs a punch . . . it’s the XR450M UHF handheld transceiver from HB Wireless – by Ross Tester Pro jects To Build 22 High Performance CLASSiC DAC; Pt.1 This high-performance stereo digital-to-analog converter is built on a single PCB and boasts three TOSLINK inputs, three S/PDIF inputs and a USB audio input. It also offers playback from an SD card – by Nicholas Vinen 28 Do-It-Yourself Seismograph With Tsunami Alarm Revised design has improved damping, an audible tsunami alarm and includes details of revised software – by Dave Dobeson Do-It-Yourself Seismograph With Tsunami Alarm – Page 28. 38 Mobile Phone Loud Ringer Ever missed an important call because you and your mobile were separated, perhaps while you were working outside? This device picks up the vibration of the mobile phone ringing and triggers a loud piezo siren – by John Clarke 60 Improved Jacob’s Ladder The high-voltage sparks climb up the vertical wires, snapping and snarling as they go. It looks and sounds spectacular and is easy to build – by Leo Simpson 74 Accurate GPS 1pps Timebase For Frequency Counters Get maximum accuracy from your new 12-Digit 2.5GHz Frequency Counter (or other counters) by adding this GPS 1pps Timebase. It can be built directly into the counter or used as a separate module – by Jim Rowe Special Columns 54 Serviceman’s Log A tale of two tablets: both dropped, both fixed 70 Circuit Notebook (1) 10Hz-100kHz Function Generator Uses MiniMaximite Display; (2) Rail-ToRail Power Amplifier For Non-Audio Use; (3) Recycling A Floppy Drive For Use As A Mini Polishing Machine Mobile Phone Loud Ringer – Page 38. 82 Vintage Radio More Philips Twins – the Dutch 209U and the Australian 112A Departments    2 Publisher’s Letter   4 Mailbag 21 Subscriptions siliconchip.com.au 53 Product Showcase 88 90 95 96 Partshop & Order Form Ask Silicon Chip Market Centre Notes & Errata Accurate GPS 1pps Timebase For Frequency Counters – Page 74. February 2013  1 SILICON SILIC CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc. (Hons.) Technical Editor John Clarke, B.E.(Elec.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc Nicholas Vinen 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 Kevin Poulter Stan Swan Dave Thompson SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $97.50 per year in Australia. For overseas rates, see the order form in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 Publisher’s Letter Texting while driving could be prevented Today’s mobile phones are wonderful pieces of technology but they are constantly being misused by irresponsible and stupid people. How many times have you seen other drivers texting while they are actually in traffic? Have you ever done this yourself? How could anyone be so stupid? But it happens all the time. Sure, this behaviour is illegal but it is virtually impossible to police because it happens so frequently. At the risk of being labelled “sexist”, this stupidity seems to be more common among young women drivers but blokes do it as well. I would like to think that any driver who was involved in an accident while texting or using a phone would be facing a jail sentence. After all, if someone was killed, surely a charge of manslaughter would be highly probable. But even if it was, that would be no certain deterrent. In fact, no legislation, no matter how draconian, will ever be able to prevent stupidity. I even think that any use of a phone in a car is a serious distraction when you are driving, even if you do have a hands-free set-up. I know that legislation against all phone use in cars is probably never going to happen because so many people do work from their cars. But perhaps phones could be prevented from providing any other functions, such as texting, reading emails, browsing the internet and even track changing while you are playing music. Technically, this would be simple to achieve, provided the phone had an in-built GPS receiver, which most smart-phones already have. The GPS would then prevent all the above-listed functions from working above a low threshold speed. In fact, the phone could probably have some input whereby it sensed that the car’s engine was running. If so, most phone functions would be disabled. The technology to do this is available right now. For example, the Australian company Humming Bird Electronics makes a GPS switch which could be the basis of this function (see http://hmbe.com.au/products/gps-speed-switch). Maybe such a system should be used to disable all phone use. If this seems too drastic for all those people working from cars, then so be it. If they were waiting on an important in-coming call or needed to make some calls, they would have to pull over and stop the engine. If they didn’t like it, tough! It would not be a big step for the legislators in this country to flag up a move to have all cars fitted with such technology. It would be a condition of registering your car. Furthermore, it would not be all that hard for this GPS over-ride device to broadcast a signal so that police cars in the vicinity can check that it is functioning. They can already easily check whether a car is fitted with a radar detector or is legally registered. Ultimately, if Australia and other countries want to further reduce the road toll, legislation to prevent behaviour is not the way to go. Technology should be used wherever possible, provided of course, that it is cost-effective. Whether that means improving the roads themselves, the signalling and sign-posting and so on, or technical modifications to cars (and phones), so be it. Legislation can only go so far as a deterrent against stupid and irresponsible behaviour. Technology can and should be used as well. Leo Simpson Recommended and maximum price only. 2  Silicon Chip siliconchip.com.au 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”. Federal Government won’t rein in power costs While I agree with your statements about smart meters and gold plating etc (Publisher’s Letter, December 2012), please don’t lose sight of the aim of this “public debate”. The Federal Government raised the story to divert attention from carbon tax and federal energy program waste onto the states. By keeping this ball in the air, we are serving their strategy. Let’s talk about state issues before state elections and federal issues before federal elections. As electors and being in the engineering sector we should be asking why Federal money is not being channelled into cross-State strategies such as interstate DC power transmission, regional load levelling schemes and possibly some real renewable energy projects rather than subsidies for panels on roofs. Incidentally, why is it that government and power producers agree that it’s necessary to charge high prices to PWM drive to LEDs may not save power In the article entitled “A HighQuality Digital Audio Signal Generator; Pt 1” in the March 2010 issue, there is a small inaccuracy in the description of the PWM control of the LCD backlight. On page 64, the author states, “The brightness [of the LCD’s backlight] is adjusted via an NPN transistor which is pulse-width modulated . . . this . . . saves battery usage because only a low-value current limiting resistor is required”. In fact, there is no saving of power through the use of PWM here. The average current in the backlight LED at the default 25% duty cycle is about 80mA and the average power dissipated in the 5.6Ω current limiting resistor is about 145mW. If PWM hadn’t been used and the resistor changed to 22.4Ω to obtain a continuous 80mA LED current, the resistor 4  Silicon Chip supply peak demand, yet they decry the price they contracted to pay for solar power exported from home solar systems at just these peak times? Kevin Shackleton, Doubleview, WA. Comments from a “valve tragic” I also visited the Sydney Hi-Fi show and I too resisted the $160,000 loudspeakers, not to mention the goldencrusted double-shielded monster speaker cables everyone seemed to have. I found the dipole and open baffle speakers impressive but like you I wondered what the same amount of money in a conventional enclosure would do. In the end I picked up a pair of VAF I-66 speakers at a fraction of the cost of some others. I’m more than happy! I think it’s pretty obvious that you see the worth of an amplifier in purely measurable performance terms – will it faithfully reproduce its input at its would still dissipate 145mW. This happens because the load is a LED which is a constant-voltage device. This results in a constant voltage of 1.8V across the dropping resistor, whatever its value. Since the average current in the resistor is constant at 80mA, regardless of whether or not PWM is used, the power lost in the resistor is also constant. With the present arrangement of the circuit, the backlight LED could be damaged in the event that the PIC’s PWM output isn’t properly set-up due to a transient fault or programming error. There is therefore a case for changing the current limiting resistor to 22Ω and increasing the default duty cycle of the PWM to 100%. Andrew Partridge, Toowoomba East, Qld. Comment: we think your calculations assume that the LED forward output, without adding distortion or losing bits of information? You are looking at it from a purely scientific/ technical perspective which is perfectly sensible. However, I bet when you look at a Norman Lindsay painting you don’t look for technical accuracy there but rather something altogether different, something alluring and mystical. The same goes for valve amplifiers. If I wanted technical accuracy I would go for solid-state every time but I prefer valve amplifiers because they change (distort) the sound in a way I like and playing music through a large valve amplifier is never boring. It’s simply more fun. My latest valve amplifier uses eight triode-connected EL509-2s and six 6SN7s in a fully balanced “Wiggins Circlotron” circuit giving about 0.7% distortion at full 60W output/channel, -3dB <10Hz - 110kHz, all with voltage does not change with current drive. It does change and given the rather large level of overdrive, it is quite a significant increase, possibly close to 40%. We think that the backlight in this unit is two LEDs in series, giving a forward voltage at the nominal current level of around 4V. At much higher pulsed currents, this could increase to around 5.5V, halving the voltage across the resistor and thus its dissipation. You are correct that if the forward voltage stays the same, the dissipation in the resistor is the same regardless of the duty cycle, for the same LED average power. Also consider that persistence of vision effects mean that the apparent LED brightness does not necessarily vary linearly with the duty cycle and thus pulsed drive may be able to provide a better brightness/power ratio. siliconchip.com.au NO global feedback. Connected to the VAF I-66’s it sounds fantastic. Now that’s tragic! Hey, you even mentioned yourself that you like vinyl. I suspect you secretly long for the days of Pink Floyd and The Supremes, when spinning a record was an “event”, much more interesting than inserting a bit of plastic in some mystery slot (within reason). You should consider a good valve amplifier to go with your turntable; once you’ve had vacuum-state you’ll never go back. Seriously now, as far as a 15-inch speaker project goes, have you considered an open-baffle design? They’re easy to build, relatively inexpensive, though a bit large, can be built by anybody with a large sheet of wood and a jigsaw, and from what I hear they’re excellent performers when using the correct speakers and crossovers. Anyway, thanks for a good read. Phil Wait, Neutral Bay, NSW. Leo Simpson comments: I used to think some valve amplifiers were really good. I built the Mullard 10/10 way back then and I have heard some pretty good valve amplifiers since, including one built by Poul Kirk, who used to run Elan Audio in Perth. I am pretty sure he was using a nested feedback design. I also think that most commercial solid-state amplifiers are nowhere near as good as they could be for very little increase in cost. And most hometheatre amplifiers are pretty average and arguably a good valve amplifier may well sound better. Your example of Norman Lindsay is interesting. I am familiar with his work and must say that I regard his nudes as At Blamey Saunders hears, we invented the IHearYou® hearing aid system; self-fit hearing aids that are affordable, discreet and highly effective. We use award winning Australian digital amplifier technology, developed for use in the bionic ear, to make sound more natural and comfortable. Our IHearYou® programmer and software kit is so simple and intuitive that you can program our hearing aids in your own home. • 64 channels of digital sound • Automatic adaptive directional microphone allows you to hear better in background noise • Advanced feedback cancellation • Ultra low delay • • • • Multi-program option Telecoil Long battery life Save by buying direct from the inventors IHearYou® is a registered trademark of Blamey Saunders hears siliconchip.com.au To find out more about Blamey Saunders hears and the IHearYou® system, see Ross Tester’s article in the July 2011 issue of Silicon Chip or visit blameysaunders.com.au February 2013  5 Mailbag: continued LED lamps have poor light distribution From experience I’d like to warn people considering replacing their house lighting with LED globes. LEDs do put out more light per watt of power used but a LED is a highintensity directional spot source of illumination. Even a globe-shaped LED light primarily projects its light downwards, not in all directions like an incandescent bulb or compact fluorescent. It doesn’t bounce light off the ceiling and walls to the same degree. So the surface of a desk or table may be well lit but as soon as you sit at that desk to read or at that table to eat and your head comes between the light and what you are trying to eat or read, it is in shadow and slightly weird; some of his work is very good though. Clearly, one does look at brushwork, anatomical correctness and other technical details in forming an overall appreciation of artworks. Having said that, I do not think there is much parallel between the appreciation of art works which must inevitably be a combination of objective and subjective judgment and that of an engineered product where technical performance must be the main criteria for excellence. As far a playing vinyl records is (was) concerned, I think the whole process was a ritual. One took great care of the records and the playing harder to see. And using a higher output LED doesn’t get rid of the shadow, it just makes it worse by increasing how brightly illuminated things not in shadow are. There are LED globes that use LEDs mounted in a corn-cob shape that do project light in all directions that are much better in this regard. But the light is not emitted in a low intensity over a large area, rather from a lot of bright points, so a LED light that puts out a lot of light can be very “glarey”. LEDs are efficient and long-life but replacing existing lights with LEDs and getting a good result is more complicated that just unscrewing one and screwing the other in. Gordon Drennan, Burton, SA. equipment and obtained great satisfaction in obtaining really good sound. These days you can obtain even better sound quality but the whole process is largely devoid of ritual. Science education letter was refreshing I, along with the Publisher of this magazine, have long had concerns about the way the science curriculum is heading – especially physics, which I taught for most of my teaching career (as well as being a HSC marker of the subject for much of it). It was therefore refreshing to read William Andrew’s excellent letter in the Mailbag pages of the January 2013 issue. Such astute observations from one so young! There is not one point in Mr Andrew’s letter that I did not agree with. Indeed, his comments on the topic of AC-DC power transmission raised a smile. Some years ago, I supervised the marking of that very subject and can only say that his description is spot-on! I remember lots of scripts referring to the electrocution of cattle and execution by electric chair! The comments on the run-down state of science equipment in most state schools are also true and this is very sad when money has been wasted on the so-called Digital Education Revolution. It was with much satisfaction that I handed my doorstop (sorry, laptop) back upon retirement. I congratulate Mr Andrew on his articulate and detailed observations of the current situation. There is yet hope for the future! George Green, Wollongong, NSW. Digital TV and destructive echoes I would like to thank Mr Ted Linney for his response (Mailbag, January 2013) to my letter in November. My comments are based on some years of experience of performing TV antenna installations at sites of difficult reception in Perth. Many sites are in areas that have a history of poor/bad analog and digital TV reception. Both systems are operating side by side in adjacent channels and suffering reception problems on one or more channels. As far as I am aware, the TV stations are transmitting both systems Your Reliable Partner in the Electronics Lab ab LPKF ProtoMat E33 – small, accurate, affordable Hardly larger than a DIN A3 sheet: The budget choice for milling, drilling and depaneling of PCBs or engraving of front panels – in LPKF quality. www.lpkf.com/prototyping Embedded Logic Solutions Pty. Ltd. Ph. +61 (2) 9687 1880 6  Silicon Chip Email. sales<at>emlogic.com.au siliconchip.com.au siliconchip.com.au February 2013  7 Mailbag: continued Many uses for a 13.8V supply In the Ask SILICON CHIP pages of the October 2012 issue, reader B. G. requested a 13.8V supply for a mobile phone charger. I wondered why B. G. wanted this supply, as most, if not all, mobile phones when purchased are provided with a mains charger and car chargers need to be purchased separately if required. Maybe there is some reason why he or she needs to go this way. However, I have found that such a power supply as described has a myriad of other uses. Mine was bought over 30 years ago; it had screw terminals for the output and I added a cigarette lighter socket. It has proved invaluable over the from the same mast or tower. The only thing common to the systems are the transmitting and receiving sites and the radio propagation path. In many cases, the analog system suffers from ghosting due to echoes. All my domestic TV tuners and my DVB-T meter are commercially available items sold to the general public. They are not specially designed and tested as would be expected of broadcast-quality test equipment. The DVB-T papers I’ve read have years for bench testing automotive accessories such as GPS navigators and the MP3 FM modulator that I bought today. Jaycar sells exactly the unit request­ ed, Cat. MP-3575 ($39.95), giving a regulated 12V output at 7.5A. A less expensive option is to buy a cigarette lighter socket (PS-2003 at $3.95) and a regulated plugpack such as the MP-3486 ($21.95) which gives 12V at 1.5A. This of course requires some technical skill to connect the socket to the plugpack’s output, and get it in the correct polarity. I have no idea of B. G.’s level of expertise, so this method may be out of the question. Greg Mayman, Dover Gardens, SA. often related to computer studies and reported field strength measurements performed at a standard height of 10m in the street using a mobile set up. The research workers have been aiming for a high percentage of coverage at an acceptable bit error rate. I have yet to read a paper in which the research workers installed stationary antennas in a wide range of domestic situations subject to difficult reception conditions (ie, strong multipath) and used commercially available TV tuners/sets on general sale to the public. During antenna installations, measurements have continually been made of signal level and bit error rate and to a lesser degree spectrum analysis and echo delay. In general, most measurements were made at the antenna or a low noise masthead amplifier close to it. The Post-Viterbi (PvBER) measurement has been the most useful measurement to determine success (better than 10-7, 10-8) or failure (less than 10-3, 2 x 10-4). Regardless of the reception result and the antenna used, most of the echo delay measurements have indicated all echoes to be inside the “Guard Interval”. At sites of difficult reception, the fixed TV antenna is subject to signals from the direction of the TV station and any number of echoes from any direction. These can combine to cause complex standing waves of signal strength and corruption of data. Predicted signal levels can be rendered meaningless. This mechanism can render signals typically 10-20dB below calculations. Sometimes the spectrum analysis display shows one of two types of bite or chunk out of the channel spectrum, triangle-shaped and V-shaped. This bite can be 10-20dB or deeper and extend typically 30% or more of the channel bandwidth. The results differ from station to station, mainly depending on path profile, frequency Full range of PICAXE products in stock now! PICAXE Chips, Starter Packs, Project Boards, Experimenter Kits, Books, Software and Accessories. PICAXE 2x16 & 4x20 OLED Displays OLED displays provide much brighter displays, better viewing angles and lower current consumption than LCD displays. This module allows PICAXE projects to display (yellow on black) text interfacing via one single serial line or I²C bus. 8  Silicon Chip PICAXE Starter Packs available for 08M2, 14M2, 18M2, 20M2, 28X2 and 40X2 Microprocessors. siliconchip.com.au Circuits should have component numbers and the location, size and orientation of significant reflecting surfaces. In the early stages, the likely location of some of these echoes indicated they were coming from the back half of the antenna. Investigation of the radiation pattern of some of the typical antennae being used showed some designs had poor front-to-back (F/B) and front-to-rear (F/R) characteristics. After replacing the antenna with one of better F/B and F/R and often relocating it to a position of improved PvBER, some or most echoes were significantly decreased or eliminated and the channel became viewable. This was the proof there can be destructive echoes inside the “Guard Interval” and that they can be overcome. As I understand things, the 7MHz 8K DVB-T signal is made up of 6817 individual carriers spread across a nominal 6.66MHz bandwidth at a spacing of 977Hz. Of the carriers, 6004 are used to carry data and the remaining 813 are used for synchronisation and control. These are classified as Continual Pilots, Scattered Pilots and TPS Pilots. The triangle-shaped and V-shaped bites of the channel spectrum mentioned above are, I suspect, the result of a gradual cancellation of a large number of sequential carriers as the echo passes from one Fresnel Zone to another. I am referring to the echo crossing tens (or more) of Fresnel Zones before combining with the direct beam from Measurement Function Filter I find it annoying that in your schematics, parts lists and PCBs you don’t label ALL resistors and ALL capacitors with BOTH value and component number. Most CAD packages insist that you give all components a component number so why don’t you provide this in your description? It takes no more effort. SILICON CHIP is the only organisation I know that does not number components. I believe component numbers on PCB are more important than the component values that SILICON CHIP currently provides. I the transmitter. When a significant echo reflects off a surface that is an odd number Fresnel Zones from the direct beam, the energy reinforces the signal and an even Fresnel Zone results in reduction of signal. What I am saying is that a fixed reflection surface that’s far enough away from the main beam can cause a bite or chunk out of the multi-carrier DVB-T signal over a significant portion of its bandwidth. I am advised by a television station engineer that a loss of about 25% of the Continual and/or Scattered Pilots in the DVB-T signal can result in a break-up of the signal. Possibly this may be occurring due to an echo or echoes cancelling sufficient pilots. Unfortunately, I do not have the tools 8 LED Capture find component numbers are vital in debugging and fault finding. I am surprised that you can debug a circuit without component numbers. When I was building your USB Data Logger I had a problem with the power supply and I found it very frustrating trying to identify components on the PCB from the schematic. Peter Kay, Dromana, Vic. Comment: the reason why we don’t put component numbers and values on the diagrams is simple: we want to keep them as uncluttered as possible. We think that this makes the circuit easier to follow. to give me such detailed information. What is clear is that a significant reduction or elimination of some echoes results in improved PvBER and often a fuller spectrum. That is, echoes can be destructive and can occur in the “Guard Interval”. In my experience, it has generally been echoes that cause reception failure, not low signal level per se. Some can cause reduction and/or corruption of signal and have been inside the “Guard Interval”. The main requirement for successful reception is a good PvBER. In sites of difficult reception, this can be achieved by the suitable selection and location of the antenna in many cases. This can result in the signal being low but of good PvBER. Capture USB 2.0 OiTEZ eScope Filter Pro • • • eScope Filter Pro $148.00ea MS1317 9.0 MegaPixel Camera Polarizing Filter Measurement Software The eScope Filter Pro is a new innovative way to discover, capture and share microscopy. Whether in a classroom environment, in industry or for the hobbyist, the eScope has a wide variety of uses from plant and insect identification, to industrial applications. Powerful measurement software will measure many variations of lines, angles and circles. • X & Y Axis Adjustable Stage • 11 LED Translumination • Battery or USB Powered • Easy Lock-in-place Setup • Freely Adjustable • Heavy Base Stand Pen Microscope Stand Pen Microscope 3D Stand $55.00ea $42.60ea MS1316 MS1314 To view over 10,000 products, pricing and to buy now online, visit www.wiltronics.com.au Ph: (03) 5334 2513 | Email: sales<at>wiltronics.com.au siliconchip.com.au 39 Years Quality Service February 2013  9 60% On Save Up p Electronic Com Components Mailbag: continued Ultrasonic U ltraso Range Finder Only $14.90 Mea Measures up to 3m Suitable for Arduino and Suit mos microcontrollers most No set-up required No Mini USB Board Only $12.90 I l d FTDI FT232RL Includes USB to UART converter Easy USB interfacing for your microcontroller system em Suitable for both 3.3V and d 5V microcontrollers Dual D ual Solar olar Battery Ch Charger harger Au matically switches from Automatically on battery to the other, one on charging is complete once H High efficiency charging with PWM P Suitable for both 12V and S 24V systems 2 Only $42.90 posed Format for KitStop ¼ Page Ad We are your one-stop shop for Microcontroller Boards, on Chip Magazine February 2012 PCB Manufacture and Electronic Components www.futurlec.com.au NEW!! 12 CHANNEL 433MHz MULTI-FUNCTION Longreach Remote Control Set Here's the latest in our growing range of remote control systems. The KSRC12-1T1R-MTL has 12 x 500W relays that can be set to Momentary, Toggle (Push ON-Push OFF), or Latch/De-latch Use the KSRC12-1T1R-MTL in annunciators, appliance, lighting, scoreboard,gate and model control up to 1,000 of metres.(line-of-sight) WITH COMPACT ENCLOSURE!! Yours Now!! $67.70 inc. GST Plus $7.50 Pack & Post Low voltage domestic power distribution I wish to suggest some projects and articles for SILICON CHIP in in 2013 and for several years to come. They are all inter-related and are as follows: (1) Domestic low voltage DC distribution; (2) A series of designs for high-efficiency regulators with 12V or 5V outputs to plug into the distribution system; (3) Universal (or a series if necessary) PWM constantcurrent regulators for LED lighting; (4) A series of dimmable triple regulators for tri-colour LEDs, taking account their different forward voltages; and (5) Articles on powering the domestic distribution system directly from solar or other off-grid sources. With domestic distribution, apart from providing an alternative to the millions of plugpacks we currently use, it could be driven from a solar source. There is a need to set some voltage standards and to define some outlet standards. Thereafter, it could be wired per the current wiring rules. As a first bid for voltage, I would suggest centre-tapped 48V, with most items using 24V. It is safe and would be more tolerant of voltage drops than perhaps a 12V0-12V system. However, this is a matter which should be discussed widely. The other matter is getting suitable outlets and plugs. I favour a 3-pin, polarised system with a flat pin plug which is not like any of the existing plug systems but permits a user to wire to the two outer wires or between the centre pole and one outer as needed. Again, this is a matter for design in cooperation with accessories manufacturers but the re-use of existing pin designs would be feasible. The existing Jones plugs have flat pins which have a rating of 10A, which should be more than adequate for most applications. As it is ELV, switching of outlets is not necessary. Whilst primarily aimed at computer and entertainment areas where plugpacks abound, it could also come in handy in offices, helping to eliminate the multiple multi-outlet plug boards. As I understand it, Standards Australia requires any new standard to be produced at virtually nil cost to them, so we (SILICON CHIP and its readership) would Our 5 Kit Bonanza is Back!! Ask about School and Club Discounts Here's a great offer to start to 2013 A kit collection that includes our FK109 2 LED Flasher, FK233 EmergencyVehicle Siren with speaker, FK908 Soil Moisture Indicator, FK602 2W Audio Amplifier (Uses the FK233 Siren speaker) and the FK401 LightActivated Switch Allinc.5GST kits for $23.43 Plus $7.50 Pack & Post For details and to buy on-line www.kitstop.com.au P.O. Box 5422 Clayton Vic.3168 When this occurs, a suitable low noise masthead amplifier close to the antenna can be used to deliver a good signal to the TV tuner/set. If the signal has a poor PvBER, the use of a masthead amplifier will do nothing to improve the situation. The authorities implementing DVB-T transmissions do have coverage problems to overcome. In Perth, for example, they are planning to install a Band 5 UHF Single Frequency Network for five stations for this reason. Coverage estimates can be seen on the Digitalready website. I understand that such measures are also being imple- Tel:0432 502 755 10  Silicon Chip siliconchip.com.au The Convenient All-in-One Solution need to do the work which would form a very interesting for Custom-Designed Front Panels & Enclosures project. Rather than making this an Australian Standard we should perhaps aim for an international standard! FREE There is an IEC standard but it uses round pins. Software Having eliminated mains-operated plugpacks, there will still be need to provide mainly 12V and 5V supplies. I for one would appreciate a small regulator with about Only 90.24 USD five USB outlets to enable me to have a single source to with custom logo engraving charge iPhone, iPad and sundry other devices demanding a USB 5V supply. Similarly, 12V is required for other We machine it You design it uses such as LED strip lighting, modems and routers. and ship to you a to your specifications using High-power LED lighting appears to need constant professionally finished product, our FREE CAD software, current for best performance and life. It would appear no minimum quantity required Front Panel Designer that PWM is likely to give the highest efficiency and be the most flexible. High-power LEDs of which I have ● Cost effective prototypes and production experience run at currents from 300-1500mA and will runs with no setup charges have forward voltages from about 5V to 35V. While ● Powder-coated and anodized finishes in a huge power span for a single design, surely design various colors principles can be shown and several designs produced. ● Select from aluminum, acrylic or provide Tri-colour LEDs offer a further challenge in that the your own material forward voltage of the red LED(s) is lower than that for ● Standard lead time in 5 days or express the blue and green LED(s). A constant-current driver manufacturing in 3 or 1 days compensates for this. However, I am not sure how the three regulators will perform and track under dimming control. It would seem as though there could be another microcontroller project here to get the light output in each channel proportional to the input signal. FrontPanelExpress.com Finally, as most PWM designs have a pot or variable 1(800)FPE-9060 resistor buried in the ramp generator, it would be nice to have an external input of 0-10V per channel; the standard input from an analog lighting control unit. (I won’t even tempt you to try DMX to analog conversion!) It seems crazy to generate solar power at about 60V, convert it up to 230V, feed it back into the grid and then convert it back to ELV in a myriad of plugpacks to use at Silicon Chip ad 120mmx87mm.indd 1 between 5V and 12V. It is also likely that a 230V storage battery will cost more than an equivalent LV unit Thus, setting up a 48V domestic supply (or such other voltage as determined in item 1) in a building offers an opportunity to consider skipping the 230V stage and feeding loads directly from the battery. It becomes an opportunity to minimise losses, avoid the mains grid and provide blackout protection. And we are talking here of many of the power consuming devices which are on during peak demand periods. Bob Lions, Killara, NSW. mented in other capital cities. Where I have installed TV antennas at a difficult location in this area, City Beach for example, the main reception problem to overcome has been due to destructive echoes. In summing up, I repeat that my field experience indicates that destructive echoes can occur inside the “Guard Interval” of the DVB-T signal. In many cases, this can be overcome with the suitable selection and location of the antenna. Mike Hale, SC Maylands, WA. siliconchip.com.au February 2013  11 11/14/12 7 Get rid of those power-hu From this . . Fit these 10W & 13W LED Got lots of 12V halogen down-lights? Is your electricity bill killing you? Maybe you should think about replacing those power hungry down-lights with efficient LED down-lights. By LEO SIMPSON W e know that home decorators love ’em but 12V halogen down-lights are a scourge. Because they are low voltage, consumers think that they are “low power”. Big mistake. Typical 12V halogens are rated at 50W but that is just for the lamp. Add in the power used by the step-down transformer, and you can easily be talking about 60 to 65 watts per lamp. And how many of those do you have in a typical room? Eight? Ten? Even more? That means that when you have the lights on those rooms you can easily be pulling 500 to 650 watts. Run those lamps for five or six hours a day and you can easily be paying more $300 a year, just for the lamps in one room. We know of one home-owner living on Sydney’s northern beaches (where the year-round climate is very pleasant) who complains about her quarterly electricity bill being over $1300 and she has to pay for gas for cooking and hot water as well! 12  Silicon Chip The energy costs are so high that she is thinking seriously of down-sizing. But guess what? Almost every room in this large 3-level house is lit by 12V 50W halogen down-lights. In total, there are some 50+ halogens – if they were all on simultaneously, the total lamp load would be over 3 kilowatts. Worse still, in summer that lamp load adds to the amount of cooling required from the air-conditioner. Working out how much extra load is placed on the airconditioner is not straightforward. You need to allow for the aircon efficiency in cooling mode but if you have 2kW of lamps on, and the aircon is on as well, you are probably talking about a 3kW load; at least. Run that for five or six hours a day and it is likely to cost about $2000 per annum, at Sydney’s present electricity tariffs. Thankfully, this home-owner does not have a “smart meter” otherwise she would be really being punished. Once you add in the cost of running items like a swimming pool pump, the air-conditioner itself and other appliances, siliconchip.com.au ungry halogen down-lights . . to this! D down-lights instead! it is easy to see how a large household could have a power bill of $1300 a quarter or over $5000 per annum. So as far as we are concerned, those 12V halogens have got to go. We have a slightly different problem in the SILICON CHIP offices. While the offices themselves are lit by efficient fluorescent troffers (see “Slash your factory/office lighting bills”, SILICON CHIP, May 2010), we have an entry corridor which is lit by four 12V 50W halogens. In fact, while I say “lit”, it is actually rather dim and gloomy (there are no windows) and while I am tempted to keep these lights off during the day because they are so power-hungry, turning them off means that we have a dark and forbidding tunnel. Well, it is not quite that bad but it is not all that attractive for an office entry. Not only that, but since these lights are on for around ten or more hours a day, and considering that our present tariff is $0.341/kWh + GST, the annual cost for those lights alone is relatively expensive at around $240 per annum and that is without allowing for the additional air-conditioner loading during the summer. So while our problem is minor compared to our frazzled northern beaches home-owner referred to above, it is still one that I would like to fix. Sure, we know that you can save some power by substitutsiliconchip.com.au ing 35W halogens for 50W units or better still, using LED replacements but the 35W approach is merely nibbling at the problem and the MR16 LED halogen replacements are still relatively expensive. And even then, you would still be running those inefficient 12V step-down transformers. Recently though, a press release crossed my desk and I pounced on it. It was for 10W and 13W down-lights, from Tenrod. These are intended as direct replacements for incandescent and CFL down-lights which are somewhat larger The two multi-LED down-lights we obtained from Tenrod LED Lighting: the 10W model on the left, 13W on the right. February 2013  13 First step was to disconnect the existing halogen downlight – invariably, these days, they simply plug in. While you are up there, make sure there are no power cables etc in the way. We elected to remove the ceiling tile to cut the hole, mainly because there was an existing downlight hole. But you could easily cut it “in situ” – in fact, installers would normally do this. than 12V halogen down-lights but why not use them anyway? We duly arranged for some sample units for this report. Two units are available, rated at 13W or 10W and they are available in warm white or daylight white. You can see their specs in the accompanying table. My immediate reaction on receiving the sample down-lights was that they are much more attractive than typical down-lights fitted with CFLs (compact fluorescents) and would would probably give a more even light distribution. And so it has proved to be. Our first step in doing this report was to take some photos of the corridor when the halogen down-lights were on. As you can see, the corridor is really quite dim, pools of light puncturing the gloom. Why home decorators regard these lights as attractive is beyond me! Our second step was to pull down one of the panels with its halogen lamp and transformer and measure the Altronics Hole Cutter: “a magic bit of kit” This is the hole cutter which has the Editor so enthusiastic. It’s the “Model Power X-625 Multi Functional Hole Cutter” and it’s available from Altronic Distributors (www.altronics.com.au) for $175.00 (Cat T2314) and includes the large carry case. It can be set to cut holes from 40-270mm diameter in plasterboard, plywood, acrylic sheet, etc. No, it’s not cheap, but if you’re involved in installing any type of audio, lighting, fans – anything needing a hole in the ceiling, this is the one you want! 14  Silicon Chip A couple of seconds later and the hole is cut. We clamped a sheet of particle board underneath the panel to give us some guide as to where to cut the hole – again, we wanted it in the same place as the existing halogen lamp hole. If this were being done “in situ”, ie, cutting the hole upwards, all the dust and bits would have been safely caught in the large clear plastic cowl, without any mess on the floor below. We wouldn’t mind betting that commercial installers, by now, are salivating at the thought! power consumption. It was around 62 watts. Just for the exercise, we substituted a 35W halogen and the total power consumption dropped to 45 watts. And for the sake of completeness, we substituted a LED replacement and the power dropped further to around 11W, with 5W of that being for the transformer alone. In each case though, there was a commensurate drop in brightness. So then we hooked up a 13W down-light from Tenrod and the power consumption measured 13 watts (funny that!), and that includes the electronic driver unit. The 10W downlight measured 10 watts, too. Then I decided to have a look at the light distribution of one of the 13W down-lights when temporarily positioned just below ceiling level in the corridor. The overall impression was that it gives a much wider pool of light and if you refer to the table, this is to be expected since the beam angle is 90°; much wider than the typical halogen lamp beam width of 60°. Based on that test, I decided that we could probably get away with three 13W down-lights for the corridor instead of four 50W halogens. That would mean a power saving of (4 x 62) – (3 x 13) = 209W. Wow, that is a saving of 84%! That would mean a saving on the annual power bill of around $200 (again, not allowing for changes to the airconditioning load). There is yet another very good reason for replacing halogen down-lights with LED models and it’s not that the halogens don’t last all that long. Because of the current drawn (12V/50W = ~4A), all wires and contacts (eg, between globe and holder, and between fitting and transformer) tend to oxidise quite quickly, leading to increased resistance. This means increased heat (with attendant fire risk – and firies will tell you of innumerable examples of that) and also of less-than-reliable operation. One user we know had several particularly troublesome halogen down-lights where bulbs failed regularly and often flickered and dimmed. They were fitted in a difficult-to-getto kitchen fitting which cannot easily get rid of heat. He’s has had to replace the lamp holders and lamp leads siliconchip.com.au It’s then simply a matter of holding the two spring clamps out of the way and placing the new lamp housing in the new hole. This whole process takes but seconds, especially using the Altronics hole cutter. Here’s the view from the opposite side. This also shows the scorch marks on the Gyprock from the old transformer: if it can do this, imagine how much heat you’re throwing away when ever the halogen downlight is on! Bring on the LEDs! several times and when removed, the wires and lamp holder were always oxidised and brittle. LED replacements would mean less current, less heat, less replacement, less aggro . . . 12mm chipboard to the ceiling panel and marking the new centre-point on that. If you are doing the same retro-fit on an existing plaster board ceiling and you want to use the X-265, you might be able to get around the problem by offsetting the new cut-out with respect to the smaller original cut-outs. But in any case, as we subsequently confirmed, the wide beam of these 10W and 13W units from Tenrod means that you too may be able to get away with less down-lights than you currently have. Doing it In our case, we were dealing with a suspended ceiling which has Gyprock panels measuring 1200 x 600mm. Rather than cutting the required holes in situ, we decided to pull each panel down and do the job in our warehouse. Furthermore, rather than messing about with a jigsaw to cut the 155mm holes, we obtained a rather fancy hole-saw from Altronics (Cat T-2314) . Called a “Model Power X-265 multi-functional hole cutter”, this is a magic bit of kit and would be a boon to anyone installing down-lights, flush loudspeakers, ceiling fans or anything with a circular mounting hole. It has a central drill and a cutting bar with two adjustable blades and it will do holes from 40 to 270mm in diameter in material thickness from 5 to 50mm thick. You just mark and punch the centre-point of the required holes, position the central drill on the punched depression and whammo, the hole is done in less than a second. But the beauty of the X265 is that it has a large transparent cowl which traps all the dust and chips so that the mess is contained. More importantly, when drilling “upward” you don’t get an eye-full of debris which can put a dampener on the whole job. This tool is not cheap but it is a great advance on ordinary hole saws (which in the size required – 165mm – are also not cheap!). However there is a problem when you want to cut a larger diameter hole centred on an existing hole for a halogen down-light. We solved that problem by clamping a sheet of TENROD LED DOWN-LIGHTS: brief specifications Model 10W 13W Voltage: 100-240V AC 1000-240V AC Beam angle: 90° 90° Working temperature: -20~40°C -20~40°C LED luminous efficacy: >100lm/W >100lm/W System efficacy: >45lm/W >50lm/W Lifetime: 35,000 hours 35,000 hours No of LEDs: 104 168 Size: 130mm x 102mm 183mm x 100mm Hole size for installation: 114mm 160mm Colours available: Daylight White or Warm White Light output: steady state light – no strobing, no flickering siliconchip.com.au Mini mains terminals If we have one criticism of the Tenrod fittings, it is the uber-tiny size of the terminals you need to connect the mains wiring to. We elected to use the two-wire mains leads fitted to the existing halogen down-lights (why buy new ones – we weren’t going to use the halogen down-lights again?). The Clipsal transformers on the old units had nice large terminal blocks but the Tenrod units have these tiny little blocks with spring-loaded connectors, which make it quite difficult to fit mains wires into – certainly not without tinning them with solder to keep them stiff enough to insert. This is not just a criticism of the Tenrod units – we’ve found in recent time most stuff coming out of Asia has similar connectors – and we get just as frustrated with them! Anyway, the photos tell the story of our installation. Instead of being dingy, the corridor is now brightly lit and welcoming. It is a great result. Final comments If you have dimmable 12V halogen down-lights be aware that these LED down-lights are not dimmable. That is usually not an issue in office, retail or commercial installations but it might be important for domestic installations. We should also comment that these LED down-lights make a great conversions from existing CFL and incandescent down-lights. They are more attractive to look at, give much better light, draw much less power and will last a very long time since rated life is 35,000 hours. At 10 hours a day, five days a week and 50 weeks a year, they should last at least 14 years! SC For further information, contact Tenrod LED Lighting, 1/24 Vore St, Silverwater NSW 2128. Tel (02) 9748 0644; Web: www.tenrod.com.au February 2013  15 THE HISTORIC RUBICON HYDROELECTRIC SCHEME By Dr David Maddison Very few people would have heard of the historic Rubicon Hydroelectric Scheme – it’s not in the national consciousness like the Snowy Mountains Scheme. But at one time it was a significant source of power, supplying almost 17% of Victoria’s electricity. L ocated about 140km east of Melbourne, construction of the entire scheme was completed in 1929 (but some parts became operational in 1928) and it is still in operation and largely original condition, although now it generates just 0.2% of Victoria’s electricity. It is an early example of a system using remote control and fault monitoring technology. It had a number of automatic features to shut the system down to prevent damage in the event of a fault condition. At one time it coexisted with major logging operations in the area and it has survived numerous bushfires. In addition, its environmental impact is relatively low. The Rubicon Scheme has very much a rustic “steampunk” aura to it and was built in a time when engineering infrastructure was built to last and remain productive for an almost indefinite time. One might surmise that the reason for this was that the rate of technological progress was much slower then than now. It made sense to build infrastructure that lasted the long 16  Silicon Chip periods of time expected until new technological developments had been made. In any case, some engineering solutions are universally applicable and at the macro level, if this scheme was constructed now it may not be much different to that implemented. The scheme includes four hydroelectric power stations ranging in capacity from 300kW up to 9.2MW, for a total capacity of 13MW as shown in the table below. The maximum output is achieved during winter. Until becoming privately owned (by AGL), the Rubicon Scheme was the oldest publicly-owned hydro scheme on Power Station Royston Rubicon Falls Rubicon (two turbines) Lower Rubicon TOTAL Total Capacity (MW) 0.8 0.3 9.2 2.7 13 siliconchip.com.au A closer look Inlet side of the Royston Power Station showing penstock. As power stations go, it’s not the largest in the world . . . the Australian mainland. The 2MW Duck Reach Power Station in Launceston, Tasmania was an older publiclyowned scheme but is no longer operational, having operated between 1895 and 1955. To put the Rubicon Scheme’s capacity into perspective, consider that the total installed hydroelectric capacity in Australia is currently 8,186MW which is about 16% of total electricity generating capacity. However the total power produced by hydro is about 5% as it is not operating at capacity. This scheme represents about 0.16% of Australia’s hydroelectric capacity. How the scheme works The hydroelectric scheme involves two rivers (Royston and Rubicon, both tributaries of the Goulburn River), four power stations, three dams, various aqueducts, penstocks (the pipes that convey water to the turbines), roads, power lines and switchgear and associated (but now unused) infrastructure such as an industrial tramway and trestle bridges. The first (most upstream) power station is the Royston (0.8MW). The water for this is supplied by the Royston Dam on the Royston River and is conducted to the station via about 2km of aqueduct and then a penstock of 549m in length. The outlet side of Royston Power Station with water discharged into aqueduct. Yes, it really is a big “tin shed”. siliconchip.com.au For those people interested in taking a closer look at most of this system they can go on a 15km bush walk starting at Rubicon Power Station. Along the trail it is possible to view the Rubicon Falls Power Station, the Rubicon Falls Dam, the Royston Power Station, beautiful scenery, aqueducts, old sawmilling and power station tramways and historic sawmill sites. The walk can be completed within one day. Note, that as with any bush walk you should only attempt it if you are suitably equipped and experienced. It is not the easiest of walks for the inexperienced, especially the final descent. Unfortunately, the power stations can be viewed from afar but no internal access is permitted. (See a suitable bushwalking guide book for the specific route.) The area can also be visited by an appropriate off-road vehicle, subject to seasonal road closures. See www.dse.vic. gov.au/–data/assets/pdf–file/0017/101744/Rubicon–Valley– Historic–Area.pdf Map courtesy of Department of Sustainability and Environment, Victoria February 2013  17 An 8.8km aqueduct delivers water to the Rubicon Power Station. Note part of the disused industrial tramway track (2ft gauge) to the left. The forebay at the end of the aqueduct that delivers water to the Rubicon Power Station. The function is to collect the water and ensure debris is trapped and removed before the water is discharged into the penstock. The water discharged from Royston enters an aqueduct, the flowing water from which is also used to power a saw mill which is no longer in regular use except for historic demonstrations. Rubicon Falls (0.3MW) is the second power station downstream in the scheme. Water is supplied to this via the Rubicon Falls Dam by a 420m long penstock. The Rubicon Power Station is the third downstream and most powerful power station in the scheme with two turbines generating up to 9.2MW. Water for this station comes via the Rubicon Dam on the Rubicon River. To reach the Rubicon Power Station the water travels along an aqueduct for a total of 8.8km. Along the way, the discharge water from the Royston Power Station (the first of the power stations) also flows into this aqueduct. A disused industrial tramway track (2ft gauge) follows the aqueduct’s path. This track could not now be used without major works as the track has been warped in places from the heat of bushfires and log-falls, among other causes. It operated until the 1990s. The forebay At the end of the aqueduct the water is discharged into a “forebay”. This consists of a water-collecting pool and grates to trap logs, sticks, leaves, rocks and other debris that has fallen into the open aqueduct, to prevent it from The Pelton wheel The Pelton wheel is a highly efficient type of water impulse turbine. Its efficient design means that nearly all the useful energy (>90%) is extracted from a water jet that impinges upon the turbines’ buckets (the impulse) transferring kinetic energy from the water jet and causing the turbine to spin. After the main work has been done, just enough kinetic energy is left in the water to remove itself from the bucket. This is achieved by causing the impinging water jet to be deflected a nominal 180° (a “U-turn” but in practice, a little less) within the bucket which results in most of its Diagram of typical Pelton kinetic energy being transferred wheel from original 1880 US Patent US000233692. to the wheel. Based upon mathematical considerations, for optimal efficiency, the velocity of the water jet is designed to be twice that of the bucket. 18  Silicon Chip Pelton wheel on display at Rubicon Power Station. This power station has two generators, each of 4.6 MW capacity and each using a horizontally mounted Pelton wheel. Note the side-by-side bucket arrangement and the heavy structure of the wheel. This was one of the original wheels used at the station and was removed when the station was upgraded for increased power in 1954-55. Often, in order to achieve better mechanical load balancing, two buckets are mounted side to side on the wheel as is the case for the Rubicon Power Station. The Pelton wheel is a commonly used type of turbine in hydroelectric installations and excels in cases of relatively low volume flow with a high head. siliconchip.com.au Hg The penstock leading to the Rubicon Power Station. The elevation drops 443m over a pipe length of 1305m. Note the riveted pipe construction. As the pipe descends toward the bottom, more rows of rivets are installed to cope with the extra pressure. Modern penstock pipe would be of seamless construction with welded joints if made from steel or be of a composite construction such as fibreglass. going into the penstock and then damaging or destroying the turbines. It also has an important safety function to prevent people who may have fallen into the fast-flowing aqueduct getting sucked into the penstock. At the forebay they presumably could safely extricate themselves from the pool of water. The forebay discharges water into the penstock, where it falls a vertical distance of 443m over a pipe length of 1305m, after which it is directed into twin Pelton wheel turbines (see box). mercury free SEE FEATU THIS IS RE SUE Lower Rubicon The final power station in the scheme is the Lower Rubicon Power Station (2.7MW). It utilises the discharge water Remote control and fault monitoring The remote control and fault monitoring functions implemented within the system were remarkably advanced for the time. Remote control was possible for opening and closing circuit breakers, starting and stopping a station and changing the electrical load of a station. There were also safety interlocks to prevent starting of a station under a fault condition; shutting down a station if a fault was detected; only allowing as much power loading as the available quantity of water could generate and prevention of power loading beyond operational limits. Automatic station shutdown would be initiated under the following fault conditions: bearing overheat, generator field failure, electrical overload, electrical insulation failure, over-voltage, single or reverse phase generator operation and generator over-speed. Remote monitoring of water parameters was also possible including stream flow, aqueduct flow, pondage water level and water flow at the turbine. siliconchip.com.au February 2013  19 Rubicon Power Station showing penstock running down the hill, the corrugated steel shed containing generating equipment and the switchyard at left. The discharge aqueduct and control gates are in the foreground. View (from afar) through the window of the Rubicon Power Station showing some of the equipment. from the Rubicon Power Station which travels 3.2km along an open aqueduct before entering a 320m long penstock. After this, water is discharged back into the Rubicon River, most of its useful energy having been extracted by the hydroelectric system. In recent times there has been a shift from large-scale hydro-generation to small-scale generation because most areas suitable for large scale generation have been fully exploited (eg the Snowy Mountains Scheme) or there are environmental concerns with further large-scale development. Also, since Australia is topographically reasonably flat, there are limited opportunities for hydro-generation compared with many other countries. Nevertheless, there remain some opportunities for exploitation of hydro resources at smaller scales, where the environmental impacts are of much less concern. Hydroelectric power can be economical and comparable to the cost of coal and gas-fuelled electricity production as well as nuclear. However, no political party in Australia is prepared to consider nuclear electricity in a serious manner. Hydro is still cheaper than “green” alternatives such as solar and wind. Perhaps for economical electricity production in the future, a choice has to be made for further limited hydro production with environmental impacts versus a nuclear option with few environmental impacts but significant political contention. Old disused tram car which was once used for conveyance of goods and equipment precariously poised at the top of the hill above the Rubicon Power Station near to the forebay. Access to the Scheme infrastructure is now by dirt roads. Author’s note: The owners of this power scheme, AGL, were invited to participate in this story but unfortunately were unable to provide any personnel familiar with the system and so information has been obtained from various other sources. SC Smaller Scale Hydro Commercial hydro-electric generation does not need to be large in scale (of the order of hundreds of megawatts). There are many small scale commercial (and also grid-feed) hydro generation projects in Australia ranging in capacity from a few kilowatts to a number of megawatts such as the Rubicon Scheme. According to one definition, “small hydro” refers to any hydro scheme below 30MW in size. Examples of some randomly selected smaller scale systems of different vintages and different areas of Australia and New Zealand include: 20  Silicon Chip The Future of Hydro in Australia Steavenson Falls at Marysville, Vic. This employs a unique cross-flow turbine. Australian Anthony Michell patented this invention in 1903. This recently rebuilt installation has a typical output of 3.3kW. Paronella Park, Qld, 25kW. Tinaroo Hydro Power station, Qld, 1.6MW. Terminal Storage Mini Hydro on the Mannum/Adelaide pipeline, SA, 1.9MW. Wellington Dam Hydro Power Station, WA, 2MW. Arnold Power Station, NZ, 3MW. Cardinia Dam Power Station, Vic, 3.5 MW. Brown Mountain Power Station, NSW, 4.5MW. Rowallan Power Station, Tas, 10.5MW. siliconchip.com.au Power: UP! Post: UP! Costs: UP! Rates: UP! C02 Tax:ON! Tax:ON! COSTS We don’t need to remind you how much costs have gone up in recent times. You see it every time you go to your mailbox. Yet the SILICON CHIP cover price has remained constant for two years – in the meantime, costs have risen across the board. There is simply no way to maintain the current price for much longer and stay in business! Therefore Prices must rise soon! That is the bad news. But there is good news: if you take out a subscription (or renew an existing sub) before the cover price increases, you will lock in the current price for the life of your subscription. You’ll not only $ave money now, you’ll $ave money later! Taking out a subscription to SILICON CHIP makes good economic sense. It is actually cheaper than buying over the counter, you are guaranteed you will never miss an issue (newsagents do sell out!) AND we pick up the postage tab. 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Current Subscription Prices: 6 Months: 12 Months: 24 Months: To Place Your Order: eMAIL (24/7) silicon<at>siliconchip.com.au with order & credit card details Within Australia Within Australia with Binder Within New Zealand Elsewhere in world $52.00 $97.50 $188.00 n/a $115.00 (1 binder) $222.00 (2 binders) $AU55.00 $AU99.00 $AU196.00 $AU80.00 $AU140.00 $AU265.00 FAX (24/7) OR To (02) 9939 2648 with all details OR INTERNET (24/7) Use PayPal to pay OR silicon<at>siliconchip.com.au PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with your credit card details OR MAIL To PO Box 139, Collaroy NSW 2097 There’s also a handy order form on P89 of this issue. . . HURRY! Prices WILL rise shortly! siliconchip.com.au February 2013  21 02/13 CLASSiC-DAC: a highperformance stereo digital-to-analog converter Pt.1: By NICHOLAS VINEN This high-performance stereo digital-to-analog converter (DAC) is based on the Cirrus Logic CS4398 as used in Marantz and other high-fidelity equipment. It has three TOSLINK inputs, three S/PDIF inputs, a USB audio input and offers playback from an SD card. As well, it has a built-in headphone amplifier, multiple status LEDs and fits in a compact low-profile case. T HE STEREO DAC project publish­ ed in September, October and November 2009 has been a very popular project. In fact, several SILICON CHIP staff members subsequently built one and now use them on a regular basis. Our new CLASSiC DAC supersedes that design and employs a better DAC chip, the Cirrus Logic CS4398, as used in the Crystal DAC upgrade (from February 2012). In addition, we 22  Silicon Chip have added many new features and obtained performance improvements. First, the new unit (the CLASSiC DAC) is more compact than the original DAC at 225 x 165 x 40mm. It requires no mains wiring, being powered from an AC plugpack, drawing about 1.5W in standby mode and about 2.5W while running, so it’s considerably more efficient than the earlier design. The S/PDIF and TOSLINK inputs have been increased to three of each. And the addition of a USB type-B socket means that you can plug it straight into a computer or other USB audio device and play back audio at up to 48kHz/16-bit without the need for any additional hardware or drivers. The addition of a high-quality headphone amplifier means that you can listen to the audio output. This, in combination with the ability to play siliconchip.com.au back WAV files from SD, SDHC or SDXC cards (up to 96kHz/24bit!), means that the CLASSiC DAC can be used as a self-contained music player. In response to reader feedback, we’ve added sampling rate LEDs which indicate either 44.1kHz, 48kHz, 96kHz or 192kHz. There are also status LEDs for each input channel. These show the active channel and whether data is present on any of the other inputs. Like our original DAC, this one also works with an infrared remote control but in addition to switching channels and changing volume, it can also be used to change tracks/folders when playing back from an SD card, put the unit into and out of standby (sleep) mode and perform other functions such as panning. When playing back WAV files from an SD card, multiple directory levels are supported. There is also the option of using digital tone controls and a digital crossfeed circuit for when headphones are being used; these extra features work with sampling rates up to 48kHz. A redesigned output filter offers slightly lower distortion than either of our previous DAC projects. Other features include click and pop suppression at power-up and powerdown for the headphone amplifier and configurable gain to suit different headphone impedances. Automatic input scanning is also improved from the earlier design as this unit can sense the state of its inputs without having to switch to them. Operation Fig.1 shows a block diagram of the siliconchip.com.au Features & Specifications • • • • • • • • • • • • • • • • • • • • Three TOSLINK inputs, supporting 32-192kHz/16-24 bit (with appropriate receiver units) Three S/PDIF coax inputs, supporting 32-192kHz/16-24 bit USB audio input, supporting up to 48kHz/16 bit (no drivers required) SD card playback, supporting up to 96kHz/16-24 bit (MMC/SD/SDHC/SDXC) Programmable automatic input selection 2V RMS stereo line outputs Stereo headphone amplifier with volume control and click/pop suppression Supports 8-600Ω headphones Digital tone control and DSP headphone cross-feed (with SD card only, up to 48kHz) Infrared remote control Powered by 6-9VAC plugpack ~3W operating power, ~1.5W standby THD+N ~0.001% <at> 1kHz (20Hz-20kHz bandwidth) Signal-to-noise ratio ~110dB Frequency response ±0.1dB 20Hz-20kHz Sampling rate indicator LEDs Input selection/status LEDs Standby/input cycle pushbutton & power indicator LED Fits in slim instrument case (225 x 165 x 40mm) with custom front & rear panels Most parts mount on a single PCB CLASSiC DAC. We are using a different digital audio receiver IC compared to our earlier DAC, a Crystal/Cirrus Logic CS8416. This is more expensive than the previously used DIR9001 but has more features which make the extra cost worthwhile. It has two internal 8-channel multiplexers and eight input amplifiers, so we don’t need external amplifiers for S/PDIF inputs nor do we need an external multiplexer to select the active input. Inputs 1-3 are TOSLINK optical in- puts which use integrated fibre optic receiver units and these produce 3.3V or 5V square-wave outputs which are fed to three inputs on the CS8416 (IC1). The USB input is channel 4 and for this we use a PCM2902 IC (IC2) to do all the hard work of communicating with the host computer and implementing the USB audio protocol. This chip similarly has a 3.3V full-scale S/PDIF output which is fed to another of IC1’s input channels. The three coaxial S/PDIF inputs February 2013  23 TOSLINK RX INPUT 1 LINE OUTPUTS TOSLINK RX L OUT INPUT 2 DIGITAL AUDIO RECEIVER (IC1, CS8416) TOSLINK RX INPUT 3 SPI REF CLK USB TYPE B SAMPLING CLOCK GENERATOR (IC7, PLL1708 & X2, 27MHz) S/PDIF (RCA) INPUT 5 CLOCK DIVIDE BY 2 (IC8, 74LV74) S/PDIF (RCA) SPI DCI (Q15, Q16) HEADPHONE VOLUME (VR1)  TOSLINK Rx POWER (3.3V OR 5V) SD/MMC SKT +15V SW INPUT 8 MUTING CON8 IR Rx S/PDIF (RCA) R OUT HEADPHONES STEREO HEADPHONE AMPLIFIER MICROCONTROLLER (64-pin dsPIC33, IC5) INPUT 6 INPUT 7 MUTING (Q1, Q2) SPI DCI USB-TO-TOSLINK CONVERTER (IC2, PCM2902) INPUT 4 STEREO DAC (IC3, CS4398) DIFFERENTIAL TO SINGLE-ENDED & LOW-PASS FILTER (IC4, LM833) +3.3V ELECTRONIC SWITCHING (DUAL MOSFETS Q12, Q13) –15V SW SPI INDICATOR LEDS 6–9V AC INPUT +5V POWER SUPPLY +15V CON9 –15V AUDIO SIGNALS: POWER: CONTROL SIGNALS: CLOCKS: Fig.1: block diagram of the CLASSiC DAC. Its main components are the CS8416 digital audio receiver (IC1), a CS4398 stereo DAC (IC3), a PLL1708 clock generator (IC7) and a dsPIC33 digital signal controller/microcontroller (IC5). The eight inputs are shown at left, while the line and headphone outputs are at right. use RCA sockets which are connected straight into three more of IC1’s input channels. Coaxial S/PDIF signals can have quite low amplitude so in this case, IC1’s internal amplifiers are required to boost the signal level high enough to allow its decoding circuitry to handle them. IC1’s eighth and last input is used to feed it audio when playing back WAV files from an SD card. The actual SD card reading is handled by microcontroller IC5 (a dsPIC33) and this then converts the WAV audio data to an S/PDIF stream which it feeds to IC1. This means that IC5 does not need to interface with the DAC directly and avoids the need for additional signal multiplexing. Once IC1 has selected and amplified the selected input signal, it then decodes the S/PDIF data and analyses it in a number of ways. Its most important task though is to extract the audio content and output it serially via an I2S (inter-IC sound) bus which 24  Silicon Chip is connected to the CS4398 DAC (IC3). IC3 converts the digital audio stream to a pair of analog signals which are fed to a low-pass filter. This converts the pairs of differential outputs from IC3 into the more typical single-ended analog outputs used by most amplifiers and other pieces of audio gear. New DAC filter We have made some changes to the filtering network in order to improve its performance. The filter used in the Crystal DAC design (February 2012), also based on the CS4398 DAC IC, used the suggested filter from the Cirrus Logic data sheet but we had rounded some of the odd component values (eg, 698Ω) to the nearest E24 series value, such as 680Ω. However we have subsequently discovered, via SPICE simulations, that even this slight shift in component values seriously degrades the ability of the filter to reject common mode signals. Obviously, the actual components won’t have the exact value printed on them so to some extent any actual filter is going to deviate from the ideal but we figure that if the filter can be shown to work effectively with exact values, it should at least perform reasonably well with real components, especially considering that 1% resistors are often much closer than 1%. Capacitors are another matter but 5% MKT types are not difficult to get and 2.5% or better are available. So we again fired up SPICE (“Simulation Program with Integrated Circuit Emphasis”). Using this software, we came up with a filter arrangement that uses only E24-series values for resistors and E12-series values for capacitors and provides (in theory at least) even better common mode signal rejection than the suggested filter in the data sheet and with a flatter frequency response, when the whole circuit is taken into account. This new filter arrangement is shown in Fig.2. Fig.3 compares its siliconchip.com.au frequency response and CMRR (common mode rejection ratio) to that of the filter as specified in the Cirrus Logic data sheet (with the unreal component values) and the filter with rounded values, as used in the Crystal DAC. Note that we have gone back to using an LM833 dual low noise op amp rather than discrete component circuitry for the audio output filters, as used in the Crystal DAC. This was to reduce the size and complexity of the overall circuit as it would otherwise be over the top. Muting & output The CS4398 supports using transistors to mute the outputs when they are idle or muted, to suppress clicks and pops. We used this feature in the Crystal DAC but we decided to use back-to-back Mosfets rather than special bipolar junction transistors as they are easier to get. We are again using this arrangement, also shown in Fig.2. However, because we have designed the DAC to use the CS4398 from the start, this unit has superior control over the muting FETs and so suppresses clicks and pops more effectively. The line outputs of the unit are taken from the outputs of the DAC filters, at the point where the muting FETs connect. These signals are also fed to the dual-gang volume control pot for the headphone amplifier. The headphone amplifier is a currentboosted op amp arrangement, reminiscent of Peter Smith’s November 2005 design although we actually redesigned it from scratch. It’s based on AmuteC 100k B AoutA+ AoutA– 24 SC 3 220 µF 1.5k 2 1 4 750Ω 1.5k 8 IC4a 1.5nF CLASSIC DAC A 47 µF ZD1 18V D2 G2 –15V 4.7nF 22nF A ZD2 18V 100nF 470Ω 6 .8 nF 2013 100Ω 25 23 470Ω K 100pF 100k 240Ω AmuteC Q3 BC559 C 10k +5V +15V E G1 100Ω Q1b S2 S1 D1 K Q1: Si4804 Q1a CON6 10nF –15V DAC OUTPUT FILTER & MUTING Fig.2: revised DAC differential low-pass output filter arrangement for the CS4398 IC. The components are arranged in the same manner as for the Crystal DAC (February 2012) but the values have been changed to provide better common mode signal rejection and to boost the output voltage level slightly while retaining a flat frequency response. another LM833 and while the performance is not quite as good as the discrete HiFi Stereo Headphone Amplifier circuit published in the September and October 2011 issues, it is still of a very high standard and well above that available from the headphone sockets of most CD players. Again, this was done to keep the overall complexity and size of the unit within reason. The gain is normally set at unity (ie, 0dB) using a pair of jumpers and this suits 8-60Ω headphones, giving an undistorted power output of around 100mW across this impedance range. For higher impedance headphones, 12dB of gain can be selected, giving around 100mW into 600Ω. Lower impedance headphones can also be used in combination with this gain but the result will be slightly more noise, possibly audible as hiss when no signal is present, depending upon the sensitivity of the headphones used. The output is via a 6.35mm stereo jack socket and the headphone amplifier is designed to endure a continuous short circuit, although typically the output is only shorted briefly when the headphone jack is inserted or removed. A second set of muting FETs are connected across the headphone outputs, as with the line outputs. This is designed to prevent the headphone amplifier output from causing a loud Why Build This High-Performance DAC? I F YOU ALREADY own a DVD player of average quality or better, you can hook it up to this DAC and immediately upgrade the sound quality. Most DVD players have mediocre audio quality from their audio outputs, especially in terms of distortion (see “DVD Players: How Good Are They For HiFi Audio?” – SILICON CHIP, October 2007). Some CD players can also have their performance improved with the addition of this DAC, provided of course that the CD player in question has a TOSLINK or S/PDIF digital output. So why are typical DVD players so poor in audio performance? Partly it is siliconchip.com.au L OUT because they are designed down to a very low price and while their on-board DAC might be quite a reasonable component, the supporting circuitry has been cut to the bone in order to keep the overall price as low as possible. It is also true that many cheap (and not so cheap) DVD players are plagued with quite strong extraneous RF in the audio outputs, mainly related to the video output signals that they continuously produce, regardless of whether they are playing DVDs or CDs. In addition, virtually all DVD players, except the most expensive models, use switchmode power supplies. These have the advantage of being very efficient and especially with respect to recent models, have very low standby power consumption. The drawback of switchmode power supplies is that they produce lots of switching harmonics which can get into the audio outputs. Finally, because all DVD players these days are double-insulated and come with 2-core power cords, they inevitably cause hum and buzz when connected to the audio inputs of high-fidelity amplifiers which are usually earthed via a 3-core mains cord. There is no simple way to fix any of these problems but this new DAC project fixes them all and provides first-class audio performance. February 2013  25 +1 80 0 70 -1 60 -2 50 -3 40 -4 -6 -7 10 30 FR (Crystal DAC) CMRR (Crystal DAC) FR (Data Sheet) CMRR (Data Sheet) FR (CLASSiC DAC) CMRR (CLASSiC DAC) -5 20 50 100 200 500 1k 2k 5k Common Mode Rejection Ratio (dB) Frequency Response (dBr) CS4398 DAC Output Filter Comparison 20 10 10k 20k 0 50k 100k Frequency (Hz) Fig.3: comparison of the frequency response and common mode rejection ratio (CMRR) of the various filter arrangements. This includes that of the Crystal DAC (using standard component values), that from the CS4398 data sheet (using non-realistic component values) and the revised standard values used in the CLASSiC DAC. The CMRR has been improved by about 18dB <at> 1kHz. thump in the headphones when power is applied or removed, due to various capacitors charging up. This works in combination with the electronic power supply switching arrangement, shown at the bottom of the block diagram. When power is first applied, the ±15V rails are switched off and it is these rails that power the op amps in both the DAC filter and headphone amplifier, as well as the current-boost transistors in the latter. This gives the muting FETs time to switch on first, after which the ±15V rails are brought up. Once the amplifier has stabilised, the FETs are switched off and the DAC can then be enabled to drive the headphones. What Are S/PDIF And Toslink? The acronym S/PDIF (or SPDIF) stands for Sony/Philips Digital Interface. Basically, it is a standardised serial interface for transferring digital audio data between consumer-level equipment such as DVD and CD players, DAT and DVD recorders, surround-sound decoders and home-theatre amplifiers. S/PDIF is very similar to the AES3 serial digital interface used in professional recording and broadcasting environments. In operation, each digital audio sample (16-24 bits) is packaged along with status, control and error-checking information into a 32-bit binary word. This is then modulated or encoded into a serial bitstream using the Biphase Mark Code (BMC). BMC involves combining the data bits with a clock signal of twice the data bit rate, in such a way that a binary “1” results in two polarity reversals in one bit period, while a binary “0” results in a single polarity reversal. This double bit-rate signal is selfclocking at the receiving end and has no DC component. The BMC encoded serial bitstream is then transmitted as a 400mV peak-to-peak signal along a single 75-ohm coaxial cable. In most cases, the cable connectors used are standard RCA or “Cinch” connectors, as also used for analog audio and composite video. Although originally developed for conveying linear PCM (LPCM) digital audio signals as used in CD and DAT audio, 26  Silicon Chip A similar procedure is used during switch-off but in reverse, ie, the muting FETs are switched on and the ±15V rails are switched off before the supply collapses entirely. WAV playback While we mentioned this capability earlier, here are some more details on WAV file playback. Note the clock generation section shown in Fig.1, to the left of microcontroller IC5. When reading a WAV file from the SD card, the micro determines the sampling rate used from the file header and must generate a matching clock, both to time the data transfer to the DAC IC and also for the DAC IC to use to reproduce the analog audio. A PLL1708 audio clock generator (IC7) is used for this purpose. It uses a 27MHz crystal and an internal PLL (phase locked loop) to generate all the common audio sampling rates, from 16kHz to 96kHz, with nine different options. It outputs up to four different clocks which are multiples of these rates, at 256, 384, 512 or 768 times. For WAV playback, to generate the required S/PDIF serial stream to send to the digital audio receiver, we need a clock that’s 128 times the sampling rate. So we take the 256x sampling rate output from IC7 and divide it by two using a low-voltage, high-speed Digital Audio Bitstream Formats SOURCE & CODING SAMPLING RATE MAX DATA BIT RATE CD-Audio (LPCM) 44.1kS/s DVD-Video & DAT (LPCM) DOLBY DIGITAL (AC-3 COMPRESSED) 96kHz 192kHz 96kS/s 192kS/s 48kS/s 6144kb/s 12.288Mb/s 448kb/s 6144kb/s 12.288Mb/s 24.576Mb/s 896kb/s 48kS/s 2822kb/s 3072kb/s SPDIF (TOSlink) 5644kb/s BMC BIT RATE DVD-Audio (LPCM) S/PDIF has also been adapted for conveying compressed digital audio, including Dolby Digital (AC-3), DTS and MPEG-2 audio. TOSLINK is essentially just the S/PDIF signal format converted into the optical domain, for transfer along optical-fibre cables. The accompanying table (see above) shows the most common domestic audio bitstream formats and the S/PDIF/TOSLINK bit rates for each one. Note that LPCM audio is rarely used for DVD-Video, because even a stereo audio track requires a BMC bit rate of 6.1Mb/s. Many current-model DVD players and recorders are provided with either coaxial S/PDIF or TOSLINK digital audio inputs and outputs, or quite often a mixture of both. Similarly, many home-theatre amplifiers are provided with coaxial S/PDIF and/ or TOSLINK inputs. This is also the case with many up-market PC sound cards. siliconchip.com.au The new CLASSiC DAC is built on a single PCB and is much more compact than our previous Stereo DAC which was built into a rack-mount case. It also has more inputs and has better performance. flipflop (IC8). This is then used to clock the dsPIC33’s Data Converter Interface (DCI). The micro selects the clock speed for the required sampling rate by sending commands to the PLL1708 using an SPI (Serial Peripheral Interface) bus. We also send the 256x (undivided) clock to the CS8416 digital audio receiver (IC1). This is used as a reference clock, when one of the other seven inputs is selected. The CS8416 contains circuitry to measure the ratio of the sampling rate of the incoming audio stream to the reference clock. Thus, by setting a known clock rate output from the PLL1708 and reading the control registers from the CS8416, the micro is able to accurately determine the incoming audio sampling rate and then displays it using the four LEDs. Control & user interface Besides the aforementioned infrared remote control and headphone volume control, the only other control input on the CLASSiC DAC is an illuminated pushbutton. This can be used to cycle through the inputs and switch the unit into and out of standby mode. The button is brightly illuminated when the unit is on and dim when the unit is powered but in standby. The rear panel carries the power input socket, seven digital audio inputs and two line outputs. The front panel has the headphone amplifier volume control, headphone socket, power siliconchip.com.au switch/LED, SD card socket and 12 status LEDs. Power supply The power supply for the original SILICON CHIP DAC was purely linear, with an 18V-0-18V toroidal transformer, full-wave rectifier, filter capacitors and linear regulators. This worked well but was quite inefficient, with the unit consuming 6-8W and the case lid above the power supply PCB becoming slightly warm during operation. To make the power supply more efficient and to allow the use of a common type of AC plugpack, the CLASSiC DAC power supply is a bit more complicated. The ±15V rails are derived using linear regulators but their input voltage is boosted using two full-wave voltage doublers. These rails are also switched off in standby mode, as the doubler greatly decreases the supply efficiency for these rails. This arrangement means that the rectified and filtered supply from which the lower voltage rails (5V & 3.3V) are derived is substantially lower and so no dropper resistor is required, with its inherent inefficiency. Also, for the 3.3V rail, from which substantial current is drawn during operation (for the micro and some of the other ICs), a switch-mode buck pre-regulator is used, to drop the 10V or so input to 3.9V with high efficiency (90+%). The 3.9V output of this switchmode regulator is then regulated to 3.3V using a linear regulator as the switchmode regulator has relatively poor ripple rejection and the CS8416 digital audio receiver IC requires a clean 3.3V rail for its PLL to operate properly and provide a low-distortion audio output. There are also several LC (inductor/ capacitor) filters in the power supply to further reduce switchmode noise, so it won’t affect analog audio performance. Since much less current is required on the 5V rail, this is derived using a 7805 linear regulator. The TOSLINK receivers operate from either the 3.3V or 5V rail, depending on which type are used, and these draw power while ever their supply is present. So to save power during standby, the supply for these units is also turned off using a Mosfet. All linear regulators use the PCB as a heatsink. Total dissipation is about 3W, spread across about 10 devices (regulators and ICs), so the copper on the PCB (and to a lesser extent, the fibreglass) is more than adequate to spread and radiate the waste heat. In operation, the case only gets slightly warm, directly above the power supply section (rear left corner). What’s coming Next month, we’ll present the full circuit details for the CLASSiC DAC and publish several graphs showing its audio performance. A final article will then describe the construction, SC testing and set-up. February 2013  27 Build your own . . . Seismograph Now with audible tsunami alarm! Back in September 2005 we presented a seismograph which was simple to build and get going. Now there is new software available which makes it easier to record earthquakes so we are presenting a slightly updated version of the original design, together with details of the revised software. The circuit also now incorporates a piezo transducer, so that the seismograph can operate independently of a computer and warn of distant quakes and possible tsunamis. By DAVE DOBESON* A USTRALIANS can be thankful that we are not normally affect­ed by the large earthquakes and volcanoes that regularly devastate so many other parts of the world. But if you travel overseas you soon become aware of just how destructive they are and their dramatic effect on the countries concerned. Add in the wholesale destruction and loss of life due to tsunamis and it is not surprising that there is continuing interest in making a seismograph. About The Author* This simple seismograph was originally described in “Scientific American” in 1979 and has been adapted for science teachers to build and use in the school laboratory – see http://science. uniserve.edu.au/school/Seismograph Dave Dobeson (ddobeson<at>bigpond.net. au) is a science teacher at Turramurra High School and the University of Sydney Science Teacher Fellowship holder for 2005. 28  Silicon Chip Designed for schools Movements of the seismograph, which is basically a horizontal pendulum, are detected using a simple light sensor circuit. In operation, a metal vane attached to one end of the pendulum (or bar) partially blocks the light between a LED and an LDR (light-dependent resistor). However, when the room moves (ie, during an earthquake), the amount of light falling on the LDR is modulated by the metal vane. The unit described here is known as a “Lehman” or “Horizontal Pensiliconchip.com.au this drives a PICAXE-08M microcontroller which functions as an analogto-digital converter. You can feed the resulting data to a computer to store, display and print the results. AmaSeis The original seismograph used PC software called StampPlot Lite to plot the results but it required several steps to see the output over more than a few hours. Since then, I have discovered “AmaSeis” (see http://pods.binghamton. edu/~ajones/AmaSeis.html) which is an excellent freeware program for use with amateur-built seismographs. Written by Alan Jones, it can accept the digital output from a number of commercial ADCs and display it as a 24-hour helical drum recording, just like professional seismographs (more on AmaSeis later). The hook at the end of the turnbuckle sits in a 5mm dimple that’s drilled into a large washer. This assembly forms the top pivot point. Building the seismograph The mechanical section of the seismograph uses parts that are readily available from a hardware store. It’s based on a swinging horizontal pendulum and movement is detected using a vane and light sensor circuit mounted at one end. dulum” seismograph. It’s also called a “Swinging Gate Seismograph”, because the bar and its supporting wire look like an old-fashioned farm gate. The “hinges” (actually the pivot points) of the “gate” are not quite vertically aligned, with the top hinge just forward of the bottom hinge so that the “gate” will swing shut. In practice, this means that the horizontal pendulum (or bar) swings slowly back to its original resting position The signal produced by the LDR is fed to an inverting op amp stage and siliconchip.com.au OK, let’s take a look at the mechanical details of our seismograph. The basic set-up comprises an 800mm-long 5/16-inch threaded steel rod that’s fitted with a 2-3kg mass at one end. The other end of the rod is ground to an edge and pivots on the end of a ½-inch bolt – this forms the lower pivot point. The supporting wire is attached to the rod at one end, just before the weights, and to a turnbuckle at the other end. This then pivots about 25-30cm above the lower pivot. If we align the seismograph pivots so that the top pivot is less than 1mm forward of the bottom pivot, then the seismograph bar will always swing back to its central position and will have a natural period of about 5-10 seconds. However, if the pivots are exactly vertically aligned, there will be no restoring force and it will never swing back. We cannot move the top pivot too far forward though, other­ wise the seismograph will be less sensitive. This unit is very sensitive to the mostly horizontal motion of earthquake “L-waves” but is insensitive to “P-waves” which are mostly vertical. Kiwis, because they are much closer to the action, might be able to detect P-waves if they use a spring instead of the wire and cut the end of the metal vane at 60°. Perth, Tennant Creek and Yass also have small local quakes every few months, so you might like to experiment with a spring support This alternative scheme for the top pivot point is an improvement on the original scheme. In this case, the hook sits in a dimple drilled into the end of a metal lever. The lever allows fine adjustment of the horizontal position of the turnbuckle hook and eliminates the need for tilt adjustment bolts (so the seismograph can now sit flat on its base). system if you live in these areas. By the way, it’s important to remember that although we often talk about the bar (or pendulum) of the seismograph “swinging”, it’s really the room that moves during an earthquake. The bar, because of the inertia of a heavy mass attached to one end, initially stays still. In effect, the unit and its associated logger act as a low-pass filter which renders the unit insensitive to everyday events (footsteps, doors closing, passing traffic, etc). The accompanying photos show February 2013  29 This labelled photograph clearly shows how the Seismograph is built. This version uses a magnetic damper but liquid damping could also be used (see the September 2005 article). Note that the light sensor and A/D converter unit shown here is an early prototype. TOP PIVOT POINT (25-35CM ABOVE LOWER PIVOT POINT) TURNBUCKLE STEEL WIRE 1-2MM DIA. 2-3KG MASS DAMPER METAL VANE LIMITING BOLTS BAR: 5/16-INCH x 800MM THREADED STEEL ROD LIGHT-SENSOR & A/D CONVERTER CIRCUIT most of the construction details. The only critical dimension is that the top pivot must be less than 1mm in front of the lower pivot. As well as the wooden frame shown, the unit could be built into any strong cupboard, bookcase, shelf or even a strong metal frame. In that case, the brackets and wooden frame would not be needed. Any type of metal rod could be used (as long as it’s strong enough) and the same goes for the mass at one end. Note that you will have to “re-zero” the seismograph for the first few weeks 30  Silicon Chip TILT ADJUSTMENT BOLTS RIGHT-ANGLE BRACKETS WITH DIAGONAL STAYS after building it, as the wire, brackets and wood flex under the strain. After that, it will be a matter of making routine adjustments every few months. Top pivot point The top “hinge” (or pivot point) is made by drilling a 5mm diameter hole about half-way through the outer section of a large, thick washer or through a flat metal lever, ie, to make a “dimple”. Small washers and a nut are used to hold the large washer or lever in position, while a nut and lockwasher This view shows the magnetic damping arrangement fitted to the prototype seismograph. It uses a couple of super magnets, a U-bracket and a large coil of wire with the ends joined. BOTTOM PIVOT POINT behind the wooden upright panel lock the bolt in place. As shown in the photos, the hook at the end of the turnbuckle sits in the dimple, so that it can freely pivot. In operation, the turnbuckle adjusts the tilt of the bar and is set so that the bar is horizontal. The securing bolt can be screwed in or out to move the top pivot point relative to the bottom pivot. This is important for the overall functioning of the seismograph because it affects the natural period of the bar (ie, the time for one complete swing A better magnetic damping scheme involves using a single super magnet which moves inside a large coil of enamelled wire wound on a bobbin salvaged from plumber’s tape. siliconchip.com.au siliconchip.com.au IN K A K 1N4004 10k 22k 8 Vss SER 2 IN VR2 5k 3 P4 P3 4 6 A LED1 PIEZO TRANSDUCER IC2 7 PICAXE P0 -08M 5 P2 P1 Vdd 1 3.3k SC 1k CON1 2013 VANE ON SEISMIC MASS 470 F 25V 9V DC IN A SIMPLE SEISMOGRAPH MK2 10k 10k* (SEE TEXT) 2 x 470 F K D1 1N4004 K LOGGER OUTPUT H L E 3.3k 3 4 7 IC1 741 10k 2 6 SENSITIVITY VR1 100k 10k LDR1   LED1 A Fig.1: the circuit uses a light detector based on LED1 & LDR1 to detect movement of an interrupter vane placed between them. The resulting signal is then amplified by IC1 and fed to the logger output. IC1 also drives IC2, a PICAXE-08M chip programmed to function as an A/D converter. Its P0 (pin 7) output is fed to the serial input of a PC which provides an alternative data logger, while the P2 (pin 5) output drives a piezo transducer for the tsunami alarm. OUT 78L05 GND 5 3 2 S T R GND +5V OUT IN REG1 78L05 100 Swinging the weight Just about any mass of 2-3kg will provide sufficient inertia to initially keep the bar still during an earthquake, provided it doesn’t hang too far below the bar. A pair of 1.25kg barbell weights are ideal for the job. They cost just a few dollars each from a sports store and come with a ready-made hole 100nF Mounting point alignment In order for the seismograph to work correctly, the lower mounting point must be directly below the upper mounting point. The best way to ensure this is to use a plum-bob made from fine fishing line and a lead sinker. The two rear-most vertical bolts that go through the support brackets are used for tilt adjustment – see photo. These both screw into threads that are tapped through the wooden base and the brackets (nuts under the wooden base will do) and each has a screwdriver slot cut into its end. This allows you to use a screwdriver to tilt the seismograph sideways and forwards or backwards, to alter the position of the bar and thus its period and sensitivity As stated above though, tilt adjustment is unnecessary if you use the lever method for the top mounting point. The far end of the seismograph wooden frame has a single central support. A sheet of plywood or particleboard underneath will stop the three supports from sinking into the carpet when the unit is positioned on the floor. SERIAL OUTPUT CON2 D9F CON3 SERIAL OUTPUT from the centre to one side, then back through the centre to the other side and finally back to the centre again). A period of about five seconds seems to work best for the author’s seismographs in Sydney. Note that the lever option is the better of the two schemes. It allows the horizontal position of the turnbuckle hook to be finely adjusted and so eliminates the need for tilt adjustment bolts (so the seismograph can sit flat on its base). The pivot end of the 5/16-inch threaded rod is ground to a knife-edge and this sits against the end of a ½-inch bolt. Wind a nut onto the rod before you cut and grind it, so that the thread is restored when the nut is removed. Be sure to use safety goggles when drilling, cutting or grinding metals – you only have one pair of eyes. February 2013  31 IC2 470 F 10k 21102131 VR2 5 E L H 10k 10k IC1 741 100nF CON2 2 3 +5V 470 F TO PIEZO 22k – + PICAXE 08M 3.3k 470 F LDR1 3.3k K REG1 78L05 10k A (SLOT IN BOX ABOVE) 100 D1 LED1 10k CON1 PIEZO TRANSDUCER 1k 9V DC IN (BEND LEADS SO LED FACES LDR1) 1N4004 CON3 SERIAL PROG D9F VR1 100k 5k LOGGER OUT Seismograph Mk2 Fig.2: install the parts on the PCB as shown here, making sure that all polarised parts are correctly orientated. IC2, REG1, VR2 and CON2 can be left out if you already have an external data logger and don’t intend using a PC. through the middle. This means they can be simply slipped over the end of the bar and clamped in position using nuts and washers on either side. Damping Once earthquake waves set the bar swinging, it will keep swinging for hours unless it is damped. Perfect damping would stop the bar after a few swings but in practice, under 2-3 minutes is OK. You can use either magnetic or liquid damping but magnetic damping is the more consistent. Magnetic damping involves attaching one or two super magnets to the end of the bar. A coil of wire with the ends joined is then placed in the magnetic field. When the bar moves (ie, during an earthquake), current is induced into the wire coil. This in turn produces a magnetic field that counters the magnet(s) and damps the motion of the bar. The accompanying photos show two alternative schemes. The best scheme is to use a single super magnet which moves inside a large coil wound on a plastic bobbin salvaged from “plumber’s tape” (this will damp the seismograph in about one minute). Just wind on as many turns of 0.71mm-diameter enamelled copper wire as you can and don’t forget to join the ends of the coil. The super magnet is attached to the threaded rod using Liquid Nails® or similar adhesive. Positioning the seismograph The ideal location for your seismograph is on a concrete block that’s set into bedrock at the bottom of a sealed mine shaft! If you don’t have access to a mine shaft(!), the seismograph should be installed in a closed room or cupboard, or in a strong bookcase surrounded by a Perspex cover (to prevent air movement over the unit). This is important because it is the location of the seismograph and the vibrations and mechanical “noise” around it that determine its ultimate sensitivity. Detector circuit details Fig.1 shows the detector circuit. Power comes from a 9V DC plugpack supply, with D1 providing reverse polarity protection. The associated 100Ω resistor and 470μF capacitor provide supply decoupling and ripple filtering. The filtered DC rail is used to power LED1 via a 1kΩ current limiting resis- tor. The LDR and its associated 10kΩ resistor effectively form a voltage divider across this supply rail, the voltage at their junction varying according to the resistance of the LDR. This in turn depends on the amount of light reaching it from the LED. The output from the LDR is fed to the inverting (pin 2) input of op amp IC1 (741) via two back-to-back 470μF capacitors. These capacitors block the DC component at the output of the LDR while allowing signal fluctuations to be fed to the op amp. They also block any slow variations in the LDR signal due to thermal variations in the room. IC1 functions as an inverting amplifier stage and its gain can be varied from 0-10 using potentiometer VR1, which is in the feedback loop. IC1’s output at pin 6 is fed to a voltage divider consisting of two 3.3kΩ resistors. The top of this divider (ie, at pin 6) can be used to directly drive an external data logger. Alternatively, the divider output (at the junction of the resistors) can be used to provide a nominal 0-5V signal, which may be required by some loggers. Pin 6 of IC1 also drives trimpot VR2 and this is used to set the maximum signal level into pin 3 of IC2, a Table 1: Resistor Colour Codes o o o o o o No.   1   4   2   2   1 32  Silicon Chip Value 22kW 10kW 3.3kW 1kW 100W 4-Band Code (1%) red red orange brown brown black orange brown orange orange red brown brown black red brown brown black brown brown 5-Band Code (1%) red red black red brown brown black black red brown orange orange black brown brown brown black black brown brown brown black black black brown siliconchip.com.au original circuit involves the addition of a piezo transducer which is driven by the P2 output (pin 5) of IC2. Hence if an earthquake is detected, the piezo transducer will immediately sound. Power for IC2 is supplied via 3-terminal regulator REG1 which provides a regulated +5V rail to pin 1. PCB assembly This view shows the completed PCB without the DB9 socket (not necessary if you intend using the 3.5mm stereo jack). Note the arrangement for the LED & the LDR. PICAXE-08M or PICAXE-08M2. IC2 is programmed to function as an analogto-digital (A/D) converter. Its serial data output is taken from pin 7 (P0) and fed to pin 2 of DB9F socket CON2. This socket is in turn connected to the serial port of a PC, to provide the alternative data logger. Of course, most PCs these days don’t have a RS232 serial interface but you can jump this hurdle by using a USB-to-serial interface cable to make the connection. As a result, this Mk.2 version of the circuit also includes a 3.5mm stereo jack socket (CON3) in parallel with the DB9F socket, with the P0 output from IC2 going to the sleeve (S). This allows the circuit to be connected to the PC via an AXE027 PICAXE USB Download Cable (from Revolution Education). This cable has a USB connector at one end and a 3.5mm stereo jack plug at the other (instead of a DB9M connector). The PICAXE-08M is programmed via pin 3 of CON2 or via the ring (R) of CON3. The incoming data is fed to pin 2 (SER IN) of IC2 via a voltage divider consisting of 22kΩ and 10kΩ resistors. The other important change to the Building the unit is easy since all the parts are mounted on a small PCB coded 21102131. Fig.2 shows the assembly details. Note that REG1 and the PICAXE (IC2) are not needed if you propose to use an external data logger (and don’t need the audible alarm). If so, these parts can simply be left out, along with the DB9F socket CON2, CON3, trimpot VR2, the 100nF capacitor and the 22kΩ and 10kΩ voltage divider resistors from pin 2 of IC2. On the other hand, if you want to have the piezo transducer, you need REG1, IC2 and their associated parts. Follow Fig.2 to install the parts on the PCB, making sure that all polarised parts are correctly orientated. IC1 & IC2 are fitted using sockets but don’t plug the ICs in yet – that step comes later. Note that the 10kΩ resistor shown in series with the LDR on Fig.1 is correct for most LDRs. However, some LDRs have a lower resistance than others in the presence of light and you may have to adjust the value of the 10kΩ series resistor accordingly. To do this, just measure the resistance of the LDR when it is fully lit by In the prototype, the LED & the LDR were brought out through holes in the case, with the seismograph’s vane sitting between them – see above. In the final version (right), the LED & LDR are inside the case and the vane rides in a slot. The vane is adjusted so that it normally “shadows” about half the LED body. siliconchip.com.au February 2013  33 Fig.3: before programming the PICAXE, you first have to select the device to be programmed in the PICAXE Programming Editor. the LED in a dark room and select a series resistor that’s about the same value. Checks & adjustments Before fitting the ICs, it’s necessary to make several voltage checks. First, connect a 9V DC plugpack supply and switch on. The LED should immediately come on. If necessary, adjust it so that it shines directly on the LDR. Next, use a digital multimeter to check the voltages on IC1’s socket pins. Pin 7 should be at the supply voltage (about 9V, depending on the plugpack), pin 2 should change when the light to the LDR is suddenly interrupted and pin 3 should be at half supply voltage. That done, check for +5V on pin 1 of IC2’s socket and for 0V on pins 2, 3, 7 & 8. Fig.4: the COM port that the detector PCB is connected to is selected using this dialog box. Here, the AXE027 cable is being used and the relevant port is COM7. If it all checks out so far, disconnect the plugpack and install IC1 (but not IC2). You now have to adjust trimpot VR2 so that the voltage on pin 3 of IC2 can never exceed 5V. This is done as follows: (1) Connect a clip lead across the two back-to-back 470μF capacitors (ie, short them out). (2) Set VR1 & VR2 to their mid-range positions. (3) Place a piece of thick cardboard between the LED and the LDR to block the light. (4) Reapply power and check the voltage at pin 6 of IC1. It should be about 1V less than the supply rail. (5) Monitor the voltage at pin 3 of IC2’s socket and adjust VR2 for a reading of 4V (or slightly less). Once that’s done, disconnect the plugpack and install the PICAXE-08M, with its notch facing to the left – see Fig.2. Final assembly The PCB is designed to fit inside a standard UB3 utility case. It’s mounted on the lid on four 9mm untapped spacers and secured using M3 x 15mm screws and nuts. That done, you have to make a cutout in one end of the case to provide clearance for the DB9F socket (CON2) and the pot shaft. This cut-out measures 45mm long x 12mm high and is about 12mm from the lip of the base. You will also need a hole in the side of the case to access CON3. You also need a hole directly in-line with the DC power socket (CON1). This is horizontally centred 17mm Fig.5: this dialog shows the main window of the PIXAXE Programming Editor after opening the software file. Clicking the Program button then downloads the software into the PICAXE (IC2). Don’t forget to adjust the alarm thresholds (see text). 34  Silicon Chip siliconchip.com.au Par t s Lis t: Seismograph Detector Fig.6: use the Terminal dialog to check that the baud rate for the transmitted data is 4800. from the lip of the case and should be drilled and reamed to 8mm. Finally, a slot must be cut in the case in line with the light sensor to provide access for the vane that’s attached to the bar. This slot should be positioned 37mm from the end of the case and can be about 4mm wide. The unit can then be assembled into the case and attached to the base of the seismograph. Position the vane so that it normally blocks about half the light between the LED and the LDR. Note: if you are using the seismograph for demonstration purposes, leave the cover off the utility box. This will let people can see how the vane partially blocks the light beam and lets them monitor how the onscreen display and the alarm respond to movement (the seismograph will, however, be sensitive to rapid changes in light level). Audible alarm How effective is the piezo transducer in sounding the alarm? Well, a recent magnitude 6.6 quake near Vanuatu (October 21, 2012) triggered the alarm for about five minutes while a larger 7.3 earthquake in the Banda Sea (near Indonesia) on December 11, 2012 set the transducer going for more than 30 minutes until the wave sequence had passed through Sydney (see Fig.7). The alarm woke me up but Berowra (just to the north of Sydney) is hardly likely to be affected by tsunamis so I did not bother to evacuate! In any case, the quake took place 150km down in the subduction zone, so there was no damage or tsunami siliconchip.com.au 1 PCB, code 21102131, 123 x 57mm 1 9V DC plugpack 1 piezo transducer (Jaycar AB-3440, Altronics S-6140) 1 2.1mm DC power socket (CON1) 1 DB9F connector (PC-mount) or 3.5mm stereo jack socket (Altronics P-0094) 1 plastic utility box, 130 x 67 x 44mm 4 9mm-long untapped spacers 4 M3 x 15mm machine screws 4 M3 nuts 1 serial computer cable or USBto-serial cable (see text) 2 8-pin IC sockets 1 100kW linear potentiometer (VR1) (Jaycar RP-8518) 1 5kW horizontal trimpot (VR2) 1 Light Dependent Resistor (LDR1) 1 3-way pin header 2 M2.5 x 6mm machine screws & nuts (to secure transducer) Semiconductors 1 741 or OP27 op amp (IC1) 1 PICAXE-08M or PICAXE-08M2 microcontroller (IC2) 1 78L05 3-terminal regulator (REG1) 1 1N4004 diode (D1) 1 red or white high-brightness LED (LED1) Capacitors 3 470mF 25V electrolytic 1 100nF MKT (code 104 or 100n) Resistors (0.25W, 1%) 1 22kW 1 1kW 4 10kW 1 100W 2 3.3kW reported. If you want to find out more, you can go online to Geoscience Australia to find the epicentre and read the tsunami warnings. Those who do live in areas at risk from tsunamis would get plenty of advance warning if the alarm sounded. That’s because earthquake waves travel more than 50 times faster than the tsunami waves, so there’s usually plenty of time to get to higher ground. Programming the PICAXE Of course, as well as adding the piezo transducer, you also have to reprogram the PICAXE-08M so that can drive the transducer (as well as correctly interact with AmaSeis). To 1 x 10kW or 1 x 3.3kW or 1 x 1kW resistor to match LDR resistance – see text Mechanical Parts 1 800mm-long x 5/16-inch threaded steel rod 5 5/16-inch nuts and washers to suit rod 1 50mm-long x 1/4-inch bolt 3 1/4-inch nuts and washers 1 40mm-long x 1/2-inch bolt 1 1/2-inch nut and washers 1 3/8-inch washer 1 1-metre length 1-2mm diameter steel wire 1 2-2.5kg mass (eg, 2 x 1.25kg barbell weights) 1 piece of thin aluminium sheet (to make vane to interrupt light beam) 1 bulldog clip (to attach metal vane to threaded rod) 1 or 2 super magnets 1 metal bracket to carry magnets (see text) 1 coil with shorted ends (see text) 2 braced right-angle brackets, 250 x 250mm 8 1/4-inch x 40mm bolts, nuts & washers 3 5/16-inch x 100mm roundhead bolts, nuts & washers 1 wooden base, 900 x 250 x 20mm 1 wooden back, 400 x 250 x 20mm Note: the PCB can be obtained from SILICON CHIP PartShop. do that, you need to first download and install the PICAXE Programming Editor on your PC. It's available for free from www.PICAXE.com/Soft­ware While you’re there, you should also grab the AXE027 USB Cable Driver (but only if you intend using the AXE027 PICAXE USB Download Cable from Revolution Education). Once the PICAXE Programming Editor software has been installed, switch off and connect the detector PCB to the PC. If you are using an old PC that has serial ports, this can be done using a standard serial cable (eg, scrounged from an old modem). If your PC doesn’t have a serial port, then you will have to use a USB-toFebruary 2013  35 Fig.7: this screen grab from AmaSeis shows the results of a 7.3 magnitude earthquake that occurred in the Banda Sea near Indonesia on December 11, 2012. It set the piezo transducer going for more than 30 minutes at the author’s location in Berowra (north of Sydney), until the wave sequence had passed. serial cable to make the connection. One option is to use the abovementioned AXE027 PICAXE USB Download Cable. However, before connecting this cable, you first have to install the driver that you downloaded earlier. This is necessary for the computer to automatically recognise the cable when it is subsequently plugged in. The AXE027 PICAXE USB Download Cable is included in the PICAXE-08M Starter Kit from Altronics – Cat. Z6101. Alternatively, you should be able to use other USB-to-serial cables, such as the Jaycar XC-4834. Unlike the Revolution Education cable which comes fitted with a 3.5mm stereo jack socket at one end, this latter cable is fitted with a DB9M connector. In each case, it’s just a matter of following the instructions supplied with the cable to install it. Programming editor With the cable connected, the next step is to launch the PICAXE Programming Editor, then click the Options button, select the Mode tab and select the device to be programmed – either a PICAXE-08M or a PICAXE-08M2 (see Fig.3). That done, click the Serial Port tab, scroll down and select the relevant COM port (see Fig.4), then click OK. You are now ready to program the PICAXE. To do this, click the Open button on the main window and load the program listing (Fig.5). To save you typing it out, this listing is available for free download from the SILICON CHIP website. The file you need is called SeismographV2.bas. Alternatively, you can type the listing out (it’s shown in the panel at right) and then copy and paste it into the PICAXE Programming Editor window (or you can just type it in directly). It’s now just a matter of clicking the Program button to download the software into the PICAXE. When you have loaded the software, you can see the transmitted data by looking at the PICAXE –> Terminal drop down menu – see Fig.6. Check that the baud rate is 4800. The value transmitted is between about 400 and 600 when the seismograph is at rest and should cover from 0 to nearly 1000 with a gentle, sustained blow on the seismograph bar. If this is incorrect, you will have to adjust the position of the metal vane and/or the sensitivity control (VR1) until you do get the full range. In the Option window, you can see which serial COM port the data is being sent through. Adjust the alarm thresholds in the program to be 100 above or below the resting value. If you make the thresholds too close, the seismograph might cry “wolf” with every breeze or footstep. Be aware also that small power supply “glitches” caused by stoves, heaters or air-conditioners might make the alarm give a single “chirp”. A real quake, however, produces a very distinct “hee-haw” sound with every “swing” of the bar. Setting up AmaSeis You must now close the PICAXE Issues Getting Dog-Eared? Keep your copies safe with our handy binders Available Aust, only. Price: $A14.95 plus $10.00 p&p per order (includes GST). Just fill in and mail the handy order form in this issue or ring (02) 9939 3295 and quote your credit card number. 36  Silicon Chip siliconchip.com.au Seismograph Program Listing main: readadc10 4,w1 sertxd (#w1,cr,lf) if w1>600 then top if w1<400 then bot pause 162 goto main ' makes a 10 bit A-D conversion of the value at input 4 and sends to w1 ' sends the value at w1 out to the Amaseis program ' sets the alarm threshold above the resting signal value (about 500) ' sets the alarm threshold below the resting signal value ' tells the picaxe to pause for 162 ms and gives 6 data feeds per second ' loops the program back to the start top: sound 2, (100,10) goto main ' when the signal >600 ' output 2 sounds a high note ' loops the program back to the start bot: sound 2, (50,10) goto main ' when the signal <400 ' output 2 sounds a low note ' loops the program back to the start Programming Editor to free the COM port, so that you can install AmaSeis. Once it’s installed, use Explorer to display the files associated with AmaSeis, then use Notepad to open the “AS1 Configuration Settings” file and change BAUD=2400 to BAUD=4800 to match the PICAXE baud rate. That done, open AmaSeis using its desktop icon, go to Settings and alter the following parameters: (1) Set the COM port number so that it is the same as for the PICAXE; and (2) Set Device to AS-1 (this was a commercial circuit using an older PIC chip). Other settings such as Station Name, Set Zero, Gain and Filters can be set later on, when the seismograph is running. Now close AmaSeis and then reopen it again from the desktop icon. You should now see a displayed seismograph line but it may be hidden above or below the screen if AmaSeis has not correctly reset it zero. In Settings –> Show Data Values, you should see the data value read by Amaseis. You might then need to use “Set Zero Level” to correct for the data value error from zero. On the main display screen, you should now see the seismograph line progress across the screen each hour. In Settings –> This Station, you can add your location and coordinates, while in Settings –> Helicorder, you can adjust the gain (5 or 10 or 20) of the computer. You should also turn Glitch Removal and Filters on. The program even appears to correct (at the end of each hour) for the few seconds gained or lost by inaccurasiliconchip.com.au Other Uses For AmaSeis Although AmaSeis is designed for use with seismographs, it could easily be put to other uses. For example, it can be used to provide a permanent record of any activity monitored by the PICAXE’s A/D inputs, eg, freezer, greenhouse or home-brew temperatures; solar panel output; cat flap position, etc. And with the PICAXE programmed with the alarm option and the added piezo transducer, it can have even more uses. cies in the PICAXE timing. The time displayed by the program is Universal Time. Analysing the display When you detect a quake, the program also has a number of options for analysing the display. “AltPrint Screen” lets you copy a quake plot to Paint for scaling or printing. And of course, if the serial cable is disconnected, the seismograph and its PICAXE-based detector circuit will operate as an independent earthquake and tsunami warning device. For further seismograph design ideas, including magnetic detector and amplifier circuits, point your browser to http://sydney.edu.au/science/uniserve_science/school/Seismograph/ index.html Finally, my thanks to Manfred for his help with the circuit design and for his continued enthusiasm for the SC project. Helping to put you in Control Control Equipment Arduino XBee Shield Simplifies the task of interfacing an XBee wireless module with your Arduino. Works with all XBee modules Series 1, 2.5, standard and Pro version. 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From CSL-4120 $24.95+GST Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au February 2013  37 Ever missed an important call because you and your mobile were separated? Here’s the SILICON CHIP solution! Mobile Phone LOUD RINGER! by John Clarke You know the scene: you’re working outside and the mobile is inside. Or maybe you’ve left it in the work ute while you’re at a job. Either way, you pick up the phone and all you see is “missed calls”. Rats! S ure, they could have left a message (but many people don't like doing that). Either way, you now have to return the call (at your cost!) and the odds are it's someone trying to flog you something you don’t want, someone who wanted you to do a job but has gone elsewhere in the meantime, someone seeking a donation to a worthy cause, or even a wrong number. Whatever it is, it’s an inconvenience. And an expense. Wouldn’t it be nice if you could hear the phone ring ’cos it's now REALLY LOUD? Yes it would be! We can’t change the ring volume on your phone itself but we can help you out by adding a mobile phone ring “extender”. This simple device picks up the vibration of the mobile phone ringing (and pretty well all mobile phones have this feature so you can “feel” the phone ringing in a noisy environment) and uses that vibration to trigger a loud piezo siren that you can position wherever you like. The vibrating alert on a mobile phone typically produces a 150-180Hz “buzz”. It’s produced by a small electric motor 38  Silicon Chip running at around 10,000rpm that rotates an eccentric (or off balance) mass on its shaft. The Mobile Phone Ring Extender (let's call it the MPRE for short) is housed in a small case. The idea is that when you don’t want the phone in your pocket or even close by, you place it on top of the MPRE case. The MPRE then provides a (very!) loud phone ring alert that allows you to get to the phone and hopefully answer it before it stops ringing. How it works Fig.1 shows the general arrangement. A piezo transducer is the sensor that detects the vibration from the phone. The vibration from the phone is transferred to the case lid and that movement is further transferred to the piezo element via an actuator made from a short length of Nylon or polycarbonate M4 thread, cut from a screw. Signal from the piezo transducer is amplified and converted to a DC voltage. This DC voltage is monitored using a comparator that compares the voltage against a reference siliconchip.com.au AMPLIFIER COMPARATOR AC TO DC CONVERTER ACTUATOR (IC1a) INTEGRATOR (D5,VR2) (D3, D4) (IC2, VR3) (IC1b, VR1) PIEZO TRANSDUCER REFERENCE VOLTAGE  CASE LID Fig.1: the basic arrangement of our Mobile Phone Ring Extender. A piezo transducer is mechanically connected to the case lid which vibrates when the phone vibrates. This signal is rectified and if high enough, causes two oscillators to function – the output of these is fed via a small driver into a piezo siren. voltage. With no signal, the DC voltage is below the reference and the comparator output is low (near to the ground supply). With vibration detected, the DC voltage rises above the reference voltage and the comparator output goes high (towards the positive supply). The following circuitry forms a delay circuit whereby the high level is integrated over time. This integrator is included so that brief vibrations – such as the phone bouncing to footsteps – are not sufficiently long enough to be detected by the following Schmitt trigger (IC2c). Only longer periods of vibration that really do mean there’s an incoming call are detected. The integrator delay is adjustable with VR2 so that the time period can be set correctly; that is, not too short to detect the placing of the phone onto the MPRE case but not too long so as to signifi- SCHMITT TRIGGER & MODULATION OSCILLATOR VOLUME VR4 DETECT LED (LED2) DRIVER (Q1) PIEZO SIREN cantly delay the detection to an incoming call. The Schmitt trigger is a part of the modulation oscillator and starts oscillation with sufficient signal from the integrator. The detect LED driven from IC2b visually indicates the detection of an incoming call. IC2b in turn drives IC2d and IC2a respectively and allows the modulation oscillator to switch the tone on and off. Modulation rate is adjustable using VR3. Output drive from IC2a is adjustable with VR4 and the wiper voltage is buffered with voltage follower Q1 to drive the external piezo siren. Circuit Circuitry for the MPRE is mainly based on just two ICs, a dual op amp (IC1) and a quad Schmitt trigger NAND gate Here’s how it works: simply place your mobile phone on top of the Mobile Phone Ring Extender (with vibrate turned on). The unit detects the vibration from incoming calls and sounds the piezo siren at right. The siren shown is one of several options; more information is in the text. siliconchip.com.au February 2013  39 +8.8V IC1: LM358 PIEZO TRANSDUCER 5 SIG 7 IC1b 6 A VR1 500k 2 100nF D3 47k 8 3 K K GND 1M D4 100nF IC1a VR2 100k D5 1 A K 4 1M 10F 1M A 100nF AC TO DC CONVERTER AMPLIFIER 22k 36k +4.4V COMPARATOR INTEGRATOR +950mV 10k 10F +8.8V 8 IC2c 5 10 9 13 4 6 3.3k VR3 500k 1F A 10F IC2a IC2d IC2b MODULATION 11 2 12 DETECT  LED1 1 14 3 7 VOLUME 1k VR4 10k Q1 BC337 100nF C B 47 E IC2: 4093B – 330 K CON1 9V DC PLUGPACK INPUT + OUTPUT TO PIEZO CON2 BUZZER S1 A K D1 1N4004 +8.8V K A POWER D2 1N5819 CON1: 2.1mm DC POWER SOCKET CON2: 3.5mm PHONO SOCKET 9V BATTERY D3–D5: 1N4148 A SC 2013 MOBILE PHONE RING EXTENDER B 1N4004, 1N5819 A LED BC337 K K E C K A Fig.2: the circuit is based on two low-cost ICs, a dual op amp (IC1) and a quad Schmitt trigger NAND (IC2). It can be operated from either a 9V battery or, for longer term operation, a 9V DC plugpack. (IC2). Fig.2 shows the full circuit. IC1b is the piezo transducer amplifier. This is biased at 4.4V using a voltage divider comprising a 47kΩ, 36kΩ and 10kΩ resistor string connected across the 8.8V supply. Pin 5 is held at this 4.4V via the 1MΩ resistor that provides a high impedance loading for the piezo transducer. Amplifier gain is set by the 22kΩ resistor connecting to the 4.4V reference and VR1’s setting. Low frequency roll off is at 72Hz, due to the 100nF capacitor in series with the 22kΩ resistor. The amplifier mainly amplifies signal above 72Hz and does not amplify a DC signal. Gain is variable from 1-23.7, with VR1 set between zero ohms to 500kΩ respectively. Output from IC1b is rectified using diodes D3 and D4. The 100nF coupling capacitor at IC1b’s output only allows AC signal to pass and the signal is clamped at about 0.7V below 0V by diode D3. Positive signal passes through diode D4 and is filtered with a 100nF capacitor. The 1MΩ resistor discharges the capacitor over a 100ms period. IC1a is the comparator that monitors the filtered DC 40  Silicon Chip voltage at the non-inverting input (pin 3) and compares this against the 950mV reference voltage at the inverting input (pin 2). The 950mV is derived from the same voltage divider that produced the 4.4V, only from the lower tapping across the 10kΩ resistor. With the pin 3 input lower than 950mV, IC1a’s output is low, at near to 0V. When pin 3 voltage rises above 950mV, then IC1a’s output goes high, at close to the 8.8V supply. This high output from IC1a charges the 10µF capacitor via diode D5 and the resistance set by VR2. When IC1a’s output is low, the 10µF capacitor discharges via the 1MΩ resistor. When the 10μF capacitor is discharged, the pin 8 input to IC2c is low and the output at pin 10 remains high, because the NAND gate output will only go low when both the pin 8 and pin 9 inputs are high. The 1μF capacitor at the second input at pin 9 is charged to a high level via VR3. IC2b inverts this high to a low output at pin 4 and so IC2d’s output also remains with its output (pin 11) high. IC2a inverts this high so that its pin 3 output sits low and there is no drive to the piezo siren. siliconchip.com.au Here’s what it looks like fully assembled, with the end-on view above showing the minimal controls. We used a “remote control” case because it already has provision for an internal 9V battery (battery and output sockets are on the side of the case in purpose-cut holes). Upon detection of a vibration signal (and the IC1a output going high), the resulting high at pin 8 of IC2c’s input allows the modulation oscillator to run. IC2c’s output goes low and discharges the 1µF capacitor via VR3 whereupon IC2c’s output goes high again to recharge the 1µF capacitor via VR3. This cycle repeats. The input threshold for the NAND gate includes hyster- esis that is internally provided within IC2. Each time IC2c’s output is low, IC2b’s output is high and this also drives the detect LED via a 3.3kΩ resistor. The LED switches on and off at the modulation rate. IC2d buffers the modulation signal from IC2b while IC2a inverts the logic level again and applies the signal across the volume potentiometer (VR4). The output at the wiper drives the base of the emitter follower Q1. When the base voltage goes high, the emitter of Q1 supplies power to the piezo siren via CON2. A 330Ω resistor is included in series with the volume control (VR4) to reduce the “dead area” at the full anticlockwise pot travel where there is no volume. The wiper voltage for VR4 needs to go above about 0.6V for Q1 to switch on. The 330Ω resistor sets the wiper voltage at 268mV when IC2d’s output is high and the wiper is set fully anticlockwise. Without this resistor, the wiper voltage would be 0V and would require more clockwise travel before sound is heard from the siren. Power for the MPRE can be either from a 9V battery or a DC supply such as from a 9V plugpack. The 9V battery supply is via Schottky diode D2 providing reverse polarity connection protection for the circuitry with minimal voltage drop. Whenever power is connected via the DC socket, the battery is automatically disconnected. Both supplies are isolated from each other by the diodes. With the 0.2V drop across diode D2, the rail voltage with a fresh battery is very close to 8.8V, as shown on the circuit diagram. It is usually a little higher from a plugpack because even though branded “9V”, the output from these can be (and usually is) anywhere up to about 12V at low currents. Why detect the vibration ? Why have we gone to the trouble of detecting the vibration of the mobile phone? Why not simply detect the ring of the phone, say via a microphone, and use that to trigger the siren? The reason is pretty simple: there are so many ring tones, so many tunes and so many variations on a theme in mobile phones that it was difficult to create a “one size fits all” detector; one that would work with everything. And there was a second problem: how sensitive do you make it, so that it reliably triggers with a ring but doesn’t false trigger when the dog barks? Just about everyone has their vibration alert turned on all the time – even if the ringer itself is turned off (and that siliconchip.com.au was another problem!). So the vibration detector was the way to go – reliable, worked with all phones, etc. Believe it or not, we tried yet another method of detection based on RF. You know how the phone’s handshaking (beep beep, beepity beep beep) gets into everything? We thought this would be a great way to detect an incoming call even though mobile phone transmitter power varies significantly with distance to the cell tower. But again, we couldn’t make it reliable with all brands of phone – and it even had more problems detecting 3G calls than it did 2G. 4G? Don’t know – none of us has a 4G phone! So we figured detecting the vibration was the best option! February 2013  41 DETECT LED 330 A 100nF Mobile Phone Ring Extender 1k S1 K 3.3k VR4 10k 100nF PIEZO SIREN D3 D2 1N5819 D1 1N4004 4004 22k IC1 LM358 10k 4148 CON2 100nF 1M D3-D5: 1N4148 10F + – 100nF 36k D4 47 500k 1M 47k 100k B Q1 10F VR1 4148 C 2013 D5 4148 E 1F VR3 500k 10F VR2 IC2 4093 C BC337 1M GND SIG TO 9V BATTERY CLIP + – CON1 THREAD THROUGH HOLES FOR STRAIN RELIEF PIEZO TRANSDUCER MOUNTS ABOVE OTHER COMPONENTS ON PCB 9V DC PLUGPACK SUPPLY + – Fig.3 (above): the same-size PCB component overlay, with an early prototype photo alongside (some components have been changed since the photo was taken). While the electrolytic capacitors are shown above in traditional position, the photo at right shows that these are all “laid over” to give room for the case lid to fit. Also, the two links shown above will only be required if the PCB is single-sided. Inset at right is a close-up of the piezo transducer with a short length of 4mm nylon screw thread, used to provide a mechanical connection between the transducer and case lid. It simply relies on touching the lid; it is not glued in. “At rest” current consumption is about 6mA. Construction All components for the MPRE are mounted on a PCB coded 12110121 and measuring 63.5 x 86mm. The PCB and components are housed in a “remote control” case measuring 135 x 70 x 24mm. This case is used because it also houses the 9V battery. A panel label attaches to the front face of the case (or, depending on the kit source, may be supplied already printed). The PCB is designed to mount onto the integral mounting bushes within the box. Make sure the corner edges of the PCB are shaped to the correct outline so they fit into the box. They can be filed to shape if necessary using the PCB outline shape as a guide. It is rare to find faults with modern PCBs, but it’s worth checking the PCB 42  Silicon Chip for breaks or shorts between tracks or pads. Repair if necessary. Check the hole sizes for the PCB mounting holes – they should be 3mm in diameter. Assembly can now begin. Start by the inserting the resistors and use the resistor colour code table to help in reading the resistor values. A digital multimeter can also be used to measure each value – in fact, it’s a good idea because many colour bands on resistors look very similar. If you use a PCB purchased from the SILICON CHIP Partshop, it will be double-sided but other PCBs may be single sided and require two wire links (above and below IC2) to be soldered in. The diodes can now be installed and being polarised, must be mounted with the orientation as shown. IC1 should be mounted directly on the PCB since there is insufficient room (height wise) for a socket once the piezo transducer is installed. IC2 can be mounted on a socket if desired. When installing the ICs, take care to orient them correctly with the notch (or circle marking pin 1) as shown on the overlay. Capacitors can be mounted next. The electrolytic types must be oriented with the shown polarity and far enough above the board (~6mm or so) so that they can be bent over to lie parallel, or near-parallel, to the surface. Otherwise you will not be able to put the lid on. This simply means you need to have sufficient capacitor lead length to allow each part to bend over. Trimpots VR1-VR3 can be mounted next. They’re not all the same – VR2 is 100kΩ (code 104) while the others are 500kΩ (code 504). Transistor Q1 is next to install. siliconchip.com.au CON1 (DC input socket) and CON2 (3.5mm output to siren) should be mounted right down on the PCB surface. Potentiometer (VR4) and the PCB mounted switch (S1) can also be fitted. LED1 and its series 3.3kΩ resistor can be regarded as optional if you don’t require a visual indication of detected ring (leaving them out will also save a little bit of power if running from a battery). If you do fit them, mount LED1 horizontally but at a height of 6mm above the PCB. Bend its leads at 90°, 7mm back from the LED body making sure the anode lead is to the left. Panel holes The side of the base of the case needs to be filed using a rat tailed file to allow connections to both CON 1 and CON2 through the side the case. Position the PCB in the base of the case with the PCB mounting holes aligned with the mounting pillars. Mark out the socket positions and file to shape. A similar shape is required on the lid and its position is found by placing the lid onto the base of the case (with the PCB removed) and filing out the lid half for a circular hole. Before securing the PCB in place, drill out the small front edge panel for the potentiometer, switch and LED (if used). A drill guide is available and is provided with the front panel label. This can be used as a guide as to the drill hole positions. Nuts for the potentiometer and 3.5mm socket are not required. The potentiometer shaft is fitted with a knob after the front edge panel is placed over the shaft, switch S1 and the LED. Wiring Follow the wiring diagram to make the connections from the piezo transducer to the PCB. The battery clip lead is inserted first from within the the battery compartment before being looped through the strain relief holes and attaching to the PCB. Make sure the polarity is correct with the red battery clip lead as the plus lead. Piezo transducer The piezo transducer is raised above the PCB using two 6.3mm tapped standoffs. M3 screws secure the standoffs from the bottom and the piezo is secured with two more M3 screws into the standoffs. Note that the mounting holes in the piezo transducer mounting lugs will need to be carefully enlarged with a 3mm (or 1/8”) drill bit. The wires are attached to the ‘Sig’ and ‘GND’ inputs on the PCB. An M4 Nylon screw, which provides the mechanical connection between the vibrating case lid and the piezo transducer, is cut so that you have a 4mm long length of thread. The head of the screw is not used. This length is inserted into the centre hole of the piezo transducer. The length of this screw thread is important. Too short and it will not make contact with the lid. Too long and the lid will not fit onto the case without excessive bowing. The PCB is secured to the base of the case using four M3 x 6mm screws that screw into the integral mounting bushes in the box. Label As mentioned earlier, some kitset suppliers are now pre-printing labels onto their cases, so you won’t have to do anything. But if yours is blank, or you’ve assembled your own bits, the panel label for this project can be downloaded from the SILICON CHIP website (www. siliconchip.com.au). When downloaded, you can print onto paper, Resistor Colour Codes No. o 3 o 1 o 1 o 1 o 1 o 1 o 1 o 1 o 1 Value 1MΩ 47kΩ 36kΩ 22kΩ 10kΩ 3.3kΩ 1kΩ 330Ω 47Ω siliconchip.com.au 4-Band Code (5%) brown black green gold yellow violet orange gold orange blue orange gold red red orange gold brown black orange gold orange orange red gold brown black red gold orange orange brown gold yellow violet black gold 5-Band Code (1%) brown black black yellow brown yellow violet black red brown orange blue black red brown red red black red brown brown black black red brown orange orange black brown brown brown black black brown brown orange orange black black brown yellow violet black gold brown Parts List – Mobile Phone Ring Extender 1 PCB coded 12110121, 63.5 x 86mm 1 panel label 113 x 50mm 1 remote control case 135 x 70 x 24mm (Jaycar HB5610) 1 piezo siren (Jaycar AB-3456, Altronics S-6127) 1 piezo transducer (Jaycar AB3440, Altronics S6140) 1 PCB mount SPDT switch (Altronics S1421 or equivalent) (S1) 1 PCB mount DC socket (Jaycar PS-0520, Altronics P0621A) (CON1) 1 3.5mm stereo PCB mount socket (Jaycar PS-0133, Altronics P0092) (CON2) 1 3.5mm mono plug [to connect siren] (Jaycar PP-0144, Altronics P-0028) 1 knob to suit VR4 1 9V battery, with clip 8 M3 x 5mm screws 2 6.3mm long M3 tapped nylon spacers 1 M4 polycarbonate or Nylon screw (cut for a 4mm thread section without the head) 4 PC stakes (optional at wiring points) Suitable length polarised figure-8 cable if siren is to be remotely mounted Semiconductors 1 LM358 dual op amp (IC1) 1 4093 CMOS quad Schmitt NAND gate (IC2) 1 1N4004 1A diode (D1) 1 1N5819 Schottky diode (D2) 3 1N4148 switching diodes (D3-D5) 1 BC337 NPN transistor (Q1) 1 3mm high intensity LED (LED1)* Capacitors 3 10µF 16V PC electrolytic 1 1µF 16V PC electrolytic 4 100nF MKT polyester (code: 104) Resistors (0.25W, 1%) 3 1MΩ 1 47kΩ 1 36kΩ 1 22kΩ 1 10kΩ 1 3.3kΩ* 1 1kΩ 1 330Ω 1 47Ω 1 100kΩ horizontal mount trimpot (code 104) (VR2) 2 500kΩ horizontal mount trimpots (code 504) (VR1,VR3) 1 10k log 9mm potentiometer (Jaycar RP-8610 or equivalent) (VR5) * optional (see text) February 2013  43 Volume Detect Power SILICON CHIP Output to Piezo Siren Figs. 4 & 5: front panel artwork for the Mobile Phone Ring Extender, and below right the template for drilling the end (top) panel holes. These images can also be downloaded from www.siliconchip.com. au it can be more easily heard – outside, for example. In this case, you’ll need to connect a suitable length of figure-8 polarised cable to the siren and in either case, you’ll need to solder on a 3.5mm mono plug so that it can plug into the MPRE. The siren is polarised – the red (+) wire goes to the centre pin on the 3.5mm plug. If you do decide to mount the siren outside, you will need to fit it so it’s protected from the elements – under an eave, for example. Within reason, there is no limit (say to a standard suburban house boundary) to the length of wire between the piezo siren and MPRE. - Mobile Phone Ring Extender Place phone on this top panel with “vibrate” turned on Pot 7mm . LED 3mm + Switch 5mm 9VDC Input End Panel Drill Guide Testing sticky-backed photo paper or onto plastic film. When using clear plastic film (overhead projector film) you can print the label as a mirror image so that the ink is behind the film when placed onto the panel. Once the ink is dry, cut the label to size. Glue the panel to the lid of the case with silicone sealant, contact adhesive or similar glue. Where you use the clear film, a contrasting silicone colour can be used such as white or grey to show up the printing on a black panel. Clear silicone can be used for non-white panels since the panel itself will provide the contrast against the printed label. Piezo siren The piezo siren is pretty loud – you might find it loud enough to mount close to the MPRE via the short length of cable it comes with. Or you might prefer to mount the siren elsewhere, where Another “siren”? 44  Silicon Chip Initially, don’t connect the siren – it will deafen you at close range! When you switch on, using a 9V battery, there should be around 8.8V between pins 4 & 8 of IC1 and between pins 7 and 14 of IC2. Pin 2 of IC1 should be about 950mV above 0V (the GND terminal). Pin 5 of IC1 should be about 4.4V above 0V. Note that these voltages might differ a little from these values depending on the supply voltage. With a plugpack supply they will almost certainly be higher but still should be in much the same ratio. Now set VR1, VR2 and VR3 to mid position and attach the piezo siren. You should be able to trigger the MPRE into operation by repetitively tapping the case. That should introduce sufficient vibration to be detected by the piezo transducer and you should hear the alert sound and see the detect LED flash. You can adjust VR3 and VR4 for the desired sound, with VR3 adjusting the rate of switching the tone on and off. Clockwise will increase the frequency. Final testing is done with a mobile telephone (set to vibrate). Place the phone on top of the MPRE and make a call to the phone using another phone. Again, the MPRE should begin flashing the detect LED and the siren should sound. If neither happens, adjust VR1 further clockwise for more sensitivity. VR2 should be adjusted so that the MPRE does not sound unless there is an incoming call. It should not detect a single tapping on the case with your finger nail. VR2’s adjustment is usually at mid-setting but may need to be set more anticlockwise to ensure that an incoming call is detected without too much delay or more clockwise to prevent detection of single tapping on SC the case. Two piezo sirens have been specified for this project but since building the prototype, we’ve come across a possible alternative – albeit not made for the purpose but nevertheless we believe would be quite suitable. By coincidence, Jaycar Electronics advertised a “Water Leakage Alarm” (Cat LA-5163) in the January issue of SILICON CHIP for just $9.95 – cheaper than either of the piezo sirens. We weren’t particu- larly interested in detecting water but we were interested in the alarm side. 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Perfect for occasional work around the house. • 240VAC • 11mm Glue sticks pk6 to suit TH-1995 $4.95 TH-1992 was $22.95 1795 SAVE $5 SERVICE AIDS Polyurethane Potting Compound Composed of a polyurethane base designed to electrically insulate and protect against dust and moisture. 995 $ Excellent driver bit set that contains just about every bit you could ever use. It has a magnetic holder, adaptors, Phillips and slotted bits, torx, and even a wing nut driver. Fantastic! See web site for full contents. • 4P/6P/8P/10P • Interchangeable dies TH-1936 Soluble oil, grease, dust and swarf are just some of the hazards measurement tools to deal with in a workshop. These calipers are IP54 rated to withstand all these nasties. 3995 $ • Resolution: 0.01mm • Metric and imperial conversion Limited stock. • Case and battery included Not available online. TD-2084 1995 $ Temperature Controlled Soldering Station 18-Piece Mixed Bit Set A collection of commonly used driver bits in a handy rubber edged case. All stainless steel. Driver not included. See website for contents. 5995 $ An ideal entry-level soldering station for the hobby user. Comes with a lightweight iron with anti-slip grip and tip cleaning sponge, temperature adjustment from 150˚C up to 450˚C. • 40W power • Size: 135(L) x 82(W) x 70(H)mm TS-1620 1995 $ SAVE $10 Spare 0.5mm conical tip: TS-1622 $8.95 Wire Glue A conductive adhesive that enables you to make solder-free connections when you aren't able to solder. Lead-free, cures overnight. • 9ml NM-2831 Gaffa Tape Preferred by the professionals. Leaves no residue behind and sticks to most clean surfaces. • 40m roll 9 $ 95 46  Silicon Chip 2 This tool will cut, strip and crimp flat telephone cable, or Cat 5e type cable. 150mm Digital Caliper • Stainless steel • Case size: 115(L) x 50(W) x 31(D)mm TD-2111 was $29.95 $ Modular Crimp Tool 3995 1995 95 Drill not included 3995 $ $ • 100 piece TD-2038 29 • 1300˚C adjustable flame • Size: 155(H) x 35(Dia.)mm TS-1660 $ 100-Piece Driver Bit Set Universal Drill Press Stand • 70ml NM-2016 Contains all the smaller sizes you need for working on electronic gear. They have ergonomic handles with excellent non-slip grips. See website for contents. Eyeglass not included 3 $ 95 Very versatile and ideal for brazing, silver soldering, jewellery work, plumbing or general hobby use. Butane gas refill available: NA-1020 $5.95 6-Piece Screwdriver Set DUE EARLY FEBRUARY Gas Torch To order call 1800 022 888 Black NM-2812 Silver NM-2814 2395 $ ea siliconchip.com.au All savings based on Original RRP. Limited stock on sale items. Prices valid until 23/02/2013. TEST & MEASUREMENT Mini Digital Multimeter Great for the hobbyist, student, or person who needs a cheap and quick way to check a few basic electronic measurements. Test probes included. • 2000 count display • Size: 94(H) x 46(W) x 26(D)mm QM-1502 495 $ Digital Thermometer with K-Type Thermocouple Dynamo-Powered DMM Just crank the handle for 10 seconds to provide power for approx 10 minutes operation. Ideal for electrical emergencies on the car or boat. Suitable for the lab, workshop or in the field. Features an excellent measurement range from -50 to 750°C and a hold function to lock the $ 95 reading on the display. Thermocouple included. SAVE $10 • Pocket size • Accepts standard K-type thermocouples • Size: 118(L) x 70(W) x 29(D)mm QM-1602 was $39.95 29 3995 $ • Data hold • 10A current • Size: 152(L) x 78(W) x 45(D)mm QM-1547 originally $79.95 2-in-1 Network Cable Tester and Digital Multimeter Ideal for network installers or technicians and will allow the user to easily check cable integrity or measure AC & DC voltage without needing to carry two separate devices. 5995 $ • Autoranging SAVE $20 • 2000 count • Cat III 600V • Case included • Size: 162(H) x 74(W) x 44(D)mm XC-5078 was $79.95 Electrical Tester with Polarity Checking & Light The unit will indicate the nearest voltage up to 690V with polarity indication. It will also check for low impedance, continuity, do a single pole phase test and show rotary field indication. IP64 rated $ 95 housing. 39 • Includes SAVE $10 2 x AAA batteries • Size: 240(H) x 78(W) x 40(D)mm QP-2286 was $49.95 400A AC/DC Clampmeter Professional Laser Distance Meter This comprehensive measurement tool adds, subtracts and calculates area, volume and takes indirect measurements. It stores up to $ 00 20 historical $ records. SAVE 20 Battery and case included. 149 • Range: 0.05 to 50m ±1.5mm • Min/max distance tracking • Laser accuracy • Size: 110(L) x 47(W) x 28(H)mm QM-1621 was $169.00 Digital Light Meter Non-Contact AC Voltage Detector Detects AC voltages from 50 - 1000V. It can be used for detecting live mains in outlets, power boards or insulated wiring. • Green and Red LED indicators • Audible beeper indicator • 2 x AAA batteries included • LED flashlight function • 176mm long QP-2268 Pro Sound Level Meter with Calibrator Ideal for vehicle noise testing, race scrutineering, traffic noise, aircraft noise or any evidence-based noise testing. Conforms to IEC 61672-1 Class 2 for sound level meters. • External calibrator $ 00 • Min/max measurement SAVE $100 • Backlit LCD • Tripod included • Size: 278(L) x 76(W) x 50(D)mm QM-1592 was $399.00 299 siliconchip.com.au Better, More Technical 99 Featuring a simple to use and easy to read display, a bar graph extends up the screen indicating the amount of moisture. Can be used on timber, cardboard, paper, and even on hardened materials. • Electrode length: 8mm • Includes 2 x CR2032 batteries • Size: 140(H) x 48(W) x 33(D)mm QP-2292 was $69.95 95 Power Point and Leakage Tester 19 $ 4995 $ SAVE $20 49 $ • Data hold, non-contact $ 00 voltage, relative measurement SAVE $20 • Autoranging • Diode test • Jaw opening 30mm • Size: 198(H) x 66(W) x 36(D)mm QM-1563 was $119.00 Moisture Level Meter A handy lightmeter for photography, lab work, architectural, engineering and construction. Measure incident light in 4 ranges (0.01 to 200, 200 to 2,000, 2,000 to 20,000 and 20,000 to 50,000 lux). • 2000 count display • Separate Photo Detector • Size: 188(L) x 64(W) x 24(D)mm QM-1587 Easy one-hand operation makes this meter perfect for the working installer or tradesman. A quality, intermediate-level clampmeter with current ranges up to 400 amps AC and DC. 95 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. QP-2000 THOUSANDS SOLD! 1995 $ High Temperature Non-Contact Thermometer Suitable for lab, furnace, forge and small-scale foundry work. The laser pointer allows for accurate placement of the measurement point and the 30:1 distance-to-target ratio allows for accurate measurement from greater distances. • Temperature range: -50 - 1000˚C (-58 - 1832˚F) • Built-in laser pointer • Size: 230(L) x 100(H) x 56(W)mm QM-7226 was $189.00 16900 $ SAVE $20 February 2013  47 www.jaycar.com.au 3 AUDIO & VIDEO NEEDS HDMI Converters Remote Control Audio/Video Selector Switch Mobile High-Definition Link to HDMI Converter Connect up to 4 AV sources to one television and switch between them remotely. Features 4 x RCA composite/S-Video inputs and 1 x RCA composite/S-Video output. Allows you to enjoy all the functions of your MHL (Mobile High-Definition Link) enabled Smartphone on the big screen. Use a HDTV remote to control a phone using the HDMI CEC function. A great way to turn a phone into a mobile and convenient media player. • Size: 53(L) x 28(W) x 11(H)mm WQ-7421 was $39.95 • Size: 190(L) x 115(W) x 50(H)mm AC-1654 NEW 4495 $ 2995 $ 89 • 3 selectable channels • Mains adaptor included • Size: 97(D) x 54(H)mm AR-1821 HDMI to VGA Converter NEW 49900 $ DUE EARLY FEBRUARY Stereo Audio Cat5 Baluns 59 Convert your stereo audio signal for connection to UTP network cable with these handy baluns. Capable of carrying signals up to 75m, the balun fly lead connects directly from your audio system to a RJ45 cable termination. Universal Pay TV Remote Replace your lost or broken pay TV remote control. Includes buttons to operate the special record, live pause and playback features of the latest recordable digital Pay TV services. Converts video from a HDMI source for displaying on older screens/projectors which only have a VGA input. Power is drawn from the HDMI port so no external power is required. NEW • Size: 250(L) x 37(W) x 13(H)mm AC-1638 69 $ 95 • Powered from USB port • Size: 80(L) x 55(W) x 11(H)mm AC-1639 iPhone® not included Fibre Optic Audio Lead A range of fibre optic toslink cables with superb build quality. Suitable for achieving excellent audio reproduction in home cinemas that support Dolby Digital 5.1 (AC-3) surround sound, DTS, and more. 1m WQ-7301 $14.95 3m WQ-7302 $24.95 5m WQ-7303 $39.95 NEW FROM 1495 $ NEW 7995 $ WQ-7301 shown DUE EARLY FEBRUARY Ultra Slim LED/LCD Wall Brackets 5.8GHz HDMI Sender/Receiver Wirelessly pipe a 1080p HDMI source to a HDTV in another room. Saves you the hassle of installing wallplates, crawling into wall cavities, or running messy HDMI cable around the house. Comes with IR remote control. 24900 $ AR-1874 QC-3668 QC-3668 $19.95 Just plug the VGA and USB cable into your PC and it will output a HDMI signal with audio/video. 95 EACH Stereo 3.5mm to Cat5 Audio Balun Turn your old PC into a Media Centre 39 $ 1995 QC-3666 $19.95 1995 NEW NEW $ Stereo RCA to Cat5 Audio Balun $ Amplify and improve the quality of the audio playing from your device by pairing it to this Bluetooth® speaker. Runs on 4 x AAA batteries (not included) or via USB, has its own volume control and a wireless range of up to 8m. QC-3666 • Fly lead length: 140mm • Size: 37(L) x 28(W) x 25(H)mm • Requires 2 x AA Batteries • Approx 210mm long AR-1737 2 x 2WRMS Portable Wireless Bluetooth® Speaker AR-1877 4-input HDMI Switcher AR-1874 $49.95 48  Silicon Chip 4 • Supports balanced or unbalanced mic or music instruments • Mains powered • Size: 320(L) x 320(W) x 475(H)mm CS-2549 DUE EARLY FEBRUARY Control a Pay TV, DVD or Blu-Ray player from another room up to 30m away. Simply install the rechargeable battery, RF transmitter and AA adaptor into the battery compartment of the remote control with the IR receiver in front of the device and away you go! Remote control not included. $ 95 With many monitors now available with a DisplayPort input, this converter will allow you to plug the monitor directly into a HDMI output on a device. For example you could connect your Blu-Ray/DVD $ 00 player, PS3, Xbox etc to any DisplayPort equipped monitor. SAVE $10 • Size: 82(L) x 44(W) x 23(H)mm AC-1621 was $99.00 • Range: up to 25m • Includes IR extender function • Receiver/sender size: 154(H) x 92(W) x 20(D)mm AR-1877 Spare receiver AR-1876 $149.00 Includes 2 x 100W speakers, 7-channel mixer and microphone. Features built-in DSP effects, peak indicator and a variety of controls to fine-tune the audio frequency range. It can also play MP3s from an SD card or a USB flash drive. SAVE $10 IR Remote Control Extender HDMI to DisplayPort Converter to suit Pay TV • Output: 2 x 2W • Wireless frequency: 2.4GHz - 2.480GHz • Accessories: 1m AUX cable, 1m USB cable • Size: 211(L) x 56(W) x 53(H)mm XC-5205 10" Portable PA System with 7-Channel Mixer To order call 1800 022 888 Ultra thin tilting wall brackets for new LED/LCD TVs allow 15° of tilt and mount only 19mm from the wall once closed for optimal viewing experience. Mounting hardware and instructions included. • Heavy duty steel construction • Mounting profile: 19mm • Load capacity up to 25kg • VESA standard complaint For 23" - 55" LED/LCD TV Sets CW-2836 $39.95 For 40" - 65" LED/LCD TV Sets CW-2838 $49.95 FROM 3995 $ siliconchip.com.au All savings based on Original RRP. Limited stock on sale items. Prices valid until 23/02/2013. SECURITY 8 Zone Wireless Alarm Kit • Back-up battery • Size: 210(L) x 113(W) x 127(H)mm LA-5145 was $179.00 With a wireless transmission range of up to 100m, this annunciator kit is a reliable solution for monitoring traffic in and out of driveways to shops, large commercial and rural properties. Easy to install and no messy wirings. Once plugged in, the battery powered wireless doorbell button can transmit up to 100 metres chiming out one of the 32 selectable melodies. NEW • Plug 'n' play • Compact $ 95 LA-5029 14900 19 $ SAVE $30 Spare sensors and accessories to suit: Pressure Mat LA-5131 $29.95 Smoke Detector Sensor LA-5132 $34.95 Indoor 120dB Siren LA-5142 $39.95 Wireless PIR Sensor LA-5146 $39.95 Stand-alone HD Camera with Motion Detection FROM 29 $ 95 Compact, standalone day/night camera for home or office video surveillance. Features IR LEDs to see in complete darkness, and captures images at a resolution of 720p. Choose continuous or motion detection recording. Micro SD card up to 32GB required for over 9 hours of footage. Supplied with remote, AV, USB cables and rechargeable batteries. See online for our full range of spare accessories. SPY CAMERAS Hi-Tech covert surveillance options. Both look innocently simple, but secretly feature hidden technology. • Continuous recording time: over 5 hrs • Storage consumption: 1GB = approx. 18mins • Charge time: approx. 3hrs • Size with bracket: 67(L) x 67(W) x 65(D)mm QC-8019 Mini Digital Spy Camera Thumb-sized clip-mount mini digital spy recorder delivers the ultimate in discrete portable photo and video recording. • 1.3MP camera • Requires a MicroSD card • Rechargeable Li-ion battery lasts for 2 hours of non-stop recording • Size: 57(H) x 22(W) x 19(D)mm QC-8003 was $49.95 Solar Powered Annunciator Kit 240VAC Plug-in Wireless Doorbell Everything you need to get a basic wireless system set up in your home! Includes a key fob remote control, backlit LCD control panel, PIR sensor and two reed switches. Limited stock. 9900 $ 2995 $ Solar Powered Mini Window Alarms SAVE $20 Ultimate "Spy" Watch Camera Simply peel the clear backing from the self-adhesive, mount and position on the inside of a window - no tools required. Loud alarm $ 95 sounds if ea triggered. Records video with audio in AVI format and downloads/charges via the supplied USB lead. • 4GB internal memory • Stores up to 120min of video • Stores approx 1200 still pictures • 640 x 480 video resolution • Bezel size: 42(Dia.)mm Camera QC-8014 Warning: These cameras should not be placed in areas where there is an expectation of privacy 2 for $30 save $9.90 6995 $ LA-5003 shown Mini Glass Breakage/Vibration LA-5003 $19.95 Mini Magnetic Entry Alarm LA-5005 $19.95 Screen your Visitors Day or Night Cost effective slimline colour LCD video doorphone perfect for the home or office. Includes a 3.8" LCD screen, infrared CMOS camera, and an electronic door locking. • Mains power supply included • Monitor size: 125(L) x 215(H) x 23(D)mm • Outdoor camera size: 100(L) x 134(H) x 38(D)mm QC-3604 was $149.00 12900 $ SAVE $20 DIGITAL Wireless Surveillance Camera Kits Wireless camera and receiver packs provide simple and effective surveillance for the home or office. Using 2.4GHz DIGITAL technology to minimize interference and maximize range these camera and receiver packs give excellent performance. Available with a LCD screen receiver for viewing video on the go or with standard receiver for connection to an existing TV screen, both versions can also record video by adding Camera Features: an SD card (not included). • Transmission range up to 100m line of sight Receiver Features: • 380TV Lines • Quad camera or single camera view • CMOS Image sensor • Supports up to 4 cameras • Night vision distance up to 5m • Accepts SD cards up to 32GB (sold separately) • Weatherproof IP66 housing • AV output for connection to separate monitor • Size: 130(L) x 65(Dia.)mm siliconchip.com.au Better, More Technical NEW 9900 $ PROTECT YOUR CABLES Expandable PPS Sleeving This PPS (Polyphenylene Sulfide) monofilament sleeving is ideal in high temperature environments and offers a lightweight mechanical protection to your cabling. • Expands up to 3 times its diameter • Black, 2m length 3mm 6mm 10mm 15mm WH-5584 WH-5585 WH-5587 WH-5588 $2.50 $2.95 $3.95 $7.95 NEW FROM 250 $ Heat Shrinkable Braided Sleeving Used to provide added protection to cables against flames and abrasion. • Shrink ratio: 2:1 • Shrink temp: 80˚C • Length: 1.2m 19 • Warning sticker included • Size: 70(W) x 82(H) x 8(D)mm • Up to 100m transmission range • Wireless IR detector • Annunciator size: 143(L) x 110(W) x 50(D)mm • Solar panel size: 173(L) x 123(W) x 14(D)mm LA-5176 10mm 20mm 25mm 30mm WH-5620 WH-5622 WH-5624 WH-5626 $3.95 $4.95 $5.95 $6.95 NEW FROM 3 $ 95 Self-Closing Braided Wrap Protect cabling neat and tidy, and protected from abrasion, wear and tear using this flame resistant self closing wrap. • Flexible and lightweight • 2m length 6mm 9mm 13mm 19mm WH-5630 WH-5632 WH-5634 WH-5636 Camera with Standard Receiver • Size:113(L) x 113(W) x 20(H)mm QC-3672 $249.00 $6.95 $7.95 $9.95 $12.95 NEW FROM 695 $ FROM 24900 $ Camera with LCD Receiver • 7” LCD screen • Size: 197(L) x 121(H) x 21(D)mm QC-3670 $349.00 Additional cameras available separately QC-3670 QC-3674 $149.00 February 2013  49 www.jaycar.com.au 5 AUTO & OUTDOORS AUTOMOTIVE TESTERS Battery, Charger and Alternator Tester A handy device to quickly indicate the condition of your 12V car battery, charger or alternator. Buy all three and get 10% OFF • Size: 120(L) x 33(W) x 20(D)mm QP-2258 1295 $ Brake Fluid Tester Determines brake fluid quality by testing the percentage of water in the brake fluid which is indicated by five LEDs. $ 95 29 • Includes 1 x AAA battery • Size: 150mm long QP-2291 Multi-Function Circuit Tester with LCD Designed to test the electrical system of 12/24V vehicles and sends voltage to components to test functionality without jumper wires. It also tests polarity, voltage, short/open status, lights and more. • Size: 240(L) x 78(H) x 40(W)mm QM-1494 4995 $ Contains around 120 standard size automotive fuses housed in a 6 compartment storage box. 2395 $ 5W VHF Marine Radio Transceiver Powerful 5W hand-held transceiver covers all International VHF marine channels. The antenna is detachable so units can be connected to a larger antenna mounted on a boat. • 1W/5W switchable output power • LCD backlit display • One-touch emergency channel 16 • Auto power saver mode DC-1096 • Input: 12-24VDC • Output: 5VDC, 2.1A + 2.1A (4.2A total) • Size: 75(L) x 27(Dia.)mm MP-3666 11900 • Pocket-sized • Size: 100(L) x 50(W)mm QP-2297 • Size: 100(L) x 90(W) x 45(H)mm HS-8856 2495 $ Multi-function Dynamo Radio Perfect for your next camping or road trip. Crank the handle to charge the internal battery and you have a torch, music player, AM/FM radio and Smartphone charger! 1495 $ ABS Solar Cable Entry Point 2495 $ NEW 5995 $ • Blinking light mode • Size: 190(L) x 125(W) x 90(D)mm ST-3356 Can also be charged using mains adaptor or by 4 x AA batteries (not included). Can Sized Inverter A can sized modified sine wave inverter that plugs into a lighter socket then drops neatly into a cup holder. 29 $ 95 • Output Power: 150W SAVE $15 • Size: 130(L) x 60(Dia.)mm MI-5121 was $44.95 Limited Stock. Wireless Rear View Mirror Reversing Camera Kit Transmits video signals via the 2.4GHz band to the monitor which can be mounted internally or externally. The monitor fits securely over your existing rear view mirror and can be quickly removed when needed. 69 95 50  Silicon Chip 6 95 Measures tyre pressure in four units (PSI, Bar, Kgf/cm2, Kpa) and tyre tread depth to know when it's time to change tyres. Features a large backlit LCD display and blue LED light. Keep an eye on your outdoor water tank from the comfort of your own living room, up to 100m away. The transmitter unit measures the water level using an ultrasonic sensor as well as temperature. $ • 2 x 12VDC cigarette lighter sockets • 2 x USB outputs • iPhone®/iPod® holder • Size: 100(H) x 70(Dia. base) x 92(Dia - top)mm PS-2122 19 $ 3-in-1 Digital Tyre Gauge Ultrasonic Water Level Tank Meter • Wall mount or free standing • Requires 2 x AA & 6 x AAA • Receiver size: 106(L) x 97(W) x 24(D)mm • Sensor size: 47(Dia.)mm approx XC-0331 iPhone®/iPod® charger designed to fit inside your cup holder as you drive. Two way cigarette lighter sockets to free up your original socket. NEW • 3.5” LCD colour screen • Range: up to 80m • Size: 280(L) x 95(H) x 26(D)mm QM-3795 was $199.00 $ Cup Holder Power Extender Simply plug into your car's cigarette lighter socket, and you have a readily available USB charging source. Usually, at some point the solar power cables need to enter into the caravan or boat and down to the battery area. To avoid making unsightly and potentially leaky cable entries, you can use this neat product and drill out your cable entry point, and then cover it over giving you two fully waterproof cable gland cable entries that look neat and purpose built. IP67 cable glands included. Automotive Fuse Pack • 20 x 5A, 10A, 15A, 20A, 25A & 30A fuses included SF-2142 4.2A Dual USB Car Charger To order call 1800 022 888 14900 $ SAVE $50 Wireless MP3 Doorbell Connect to PC by USB, install the software pre-loaded into the unit then select, edit and save your MP3 file and away it goes. • Up to 100m transmission range • Requires 3 x AA batteries • Size: 140(L) x 95(W) x 36(H)mm LA-5024 NEW 4495 $ siliconchip.com.au All savings based on Original RRP. Limited stock on sale items. Prices valid until 23/02/2013. WORK TECH GADGETS Network Adaptor with 3 Port Hub 19 • Small and lightweight • Size: 96(L) x 24(W) x 16(H)mm YN-8407 Laptop not included • 8GB storage for approx. 3000 photos (varies based on photo size) • Plug & Play $ 00 XC-5620 Limited Stock. 99 All-in-1 Memory Card Reader Contains over 900mm of pull to extend cable for RJ11 to RJ11, USB A/M to USB A/F, USB A/M to USB A/M, FireWire 1394 6P/M to 6P/M, DC3.5, an earphone with microphone, mini USB optical mouse, connectors and 4 way USB hub. Everything you may need when $ 95 travelling. See website for full specifications. SAVE $5 XM-5280 was $24.95 Reads most memory cards in use today, including SD, MicroSD, CF cards, MS cards and many more! See website for full compatibility list. Network Cable Tracer This tone generator is a highly practical network installation and troubleshooting tool and allows cables to be easily traced by the probe, even when cables are in a bundle or hidden in punchdown blocks or wall plates. 1995 $ SAVE 5 $ An all-in-one 2.4GHz wireless keyboard and mouse solution perfectly suited to home or office PC applications. Features QWERTY keyboard and an ergonomically designed precision mouse with scroll wheel. An excellent tool kit for electronic or computer repairs with all the essentials - cutters, pliers, screwdrivers (Phillips head, slotted, Posidrive), nut drivers etc. See website for full contents. • Includes nano size USB dongle and batteries • Size: 435(L) x 125(W) x 18(H)mm $ 95 XC-5174 29 $ 95 24 Gaming Console Tool Kit Everything you need to get into your gaming console and accessories. Includes tools for pretty much every console and handheld on the market today WII®, X-Box®, Playstation® etc. See website for full contents. Portable Study Table with Notebook Cooler Features two work surfaces - the adjustable sloping rest can be used for a laptop or a book and the flat surface as a mouse pad or writing surface. Features a pen holder, cup holder and cooling fans for a laptop. • Carry case included TD-2109 • Built-in laptop cooling fans • Height adjustable • Retractable USB cable included • Size folded: 285(W) x 316(H) x 36(D)mm • Size unfolded: 570(W) x 316(H) x 36(D)mm XC-5218 2995 $ 802.11n Wireless Broadband Router Offering the latest in high speed technology, this excellent router can realise data transfer rates up to 300Mbps and achieve three times the transmission range of 802.11g systems. Integrates a router, wireless access point, four-port switch, and firewall all in one compact package. See website for full specifications. • 300Mbps receiving and 150Mbps transmission rates • SSID stealth mode and MAC address filtering YN-8300 NOTE: Actual product may differ from picture shown 1995 $ Wireless Keyboard & Mouse 30 Piece Electronic Tool Kit • Case size: 210(L) x 140(W) x 38(D)mm TD-2107 • 802.11n, 150Mbps • Size: 19(L) x 8(W) x 15(D)mm YN-8309 6995 $ siliconchip.com.au Better, More Technical 9900 $ • Size: 115(L) x 60(W) x 30(D)mm XC-5083 was $119.00 • USB 2.0 • Size: 68(L) x 40(W) x 13(H)mm XC-4926 was $24.95 19 At only 5mm wide this is the tiniest USB 2.0 network adaptor out there. Capable of up to 150Mbps and ideal for PC, laptop, or netbook. Gives a whole new dimension to capturing, storing and sharing of photos and videos wirelessly. Transfer and share precious moments from your digital camera to your PC, laptop, Tablets or Smartphones without the need for cables. Great for travellers! See website for full features and specifications. NEW Computer Cable Travel Kit Wireless Network Adaptor Wireless SD Card - 8GB For MacBook Air®, ultrabooks, netbooks and Tablets where USB ports are sparse or RJ-45 network ports are non-existent (i.e Macbook Air®). Simply $ 95 connect a network cable to this device and you have a 10/100Mbps network adaptor. SAVE $20 USB Powered PC Speakers Use with laptops, desktop PCs or mobile music players. Contemporary, space saving design with plug and play functionality. • USB powered • Power output: 1.8WRMS • Size:154(H) x 75(W) x 36(D)mm XC-5191 1495 $ Universal Remote Control with Keyboard An advanced learning universal remote control backed with full QWERTY keypad that also features optical finger navigation for mouse-like control. Perfect for media players, smart TVs, home theatre PCs, or gaming. $ 95 34 • Includes IR receiver • Size: 167(L) x 51(W) x 15(D)mm AR-1723 Front Back 2995 $ Rechargeable Bluetooth® Headset with Mic Talk hands-free while driving, or connect to your Bluetooth® enabled PC or PS3 for hands-free chat on Skype, MSN, games etc. Can pair with two Bluetooth® devices and features anti-noise technology for clear conversations. • Charges via USB • Size: 216(W) x 65(H) x 150(D)mm AA-2080 3995 $ February 2013  51 www.jaycar.com.au 7 DO IT YOURSELF! High-Energy Electronic Ignition Kit for Cars Refer: Silicon Chip Magazine Nov and Dec 2012 Use this kit to replace a failed ignition module or to upgrade a mechanical ignition system when restoring a vehicle. Use with virtually any ignition system that uses a single coil with points, hall effect/lumenition, reluctor or optical sensors (Crane and Piranha) and ECU. Features include $ 95 adjustable dwell time, output or follow input option, tachometer output, adjustable debounce period, dwell compensation for battery voltage and coil switch-off with no trigger signal. NOTE: Product will vary to one shown. T ES DG KE PY ST ST N DO Mc ALD Parking available! NOTE: Optional 10k ohm potentiometer for external volume control use RP-7610 $1.95 PC Programmable Line Tracer Kit Learn about robotics and programming with this line tracer kit. Run it in line tracer mode by drawing a thick dark line on paper for the robot to follow. • Requires 2 x AA batteries • Suitable for ages 12+ • Size: 120(L) x 64(W) x 55(H)mm KJ-8906 NEW 1995 $ 3495 $ IR Temperature Sensor Module for Arduino Connect this to your board and point it at a surface or heat source to remotely measure its temperature. This is our special version of the industrial infrared remote thermometer units with an onboard power supply, communication support and a software library and examples supplied. • 3.3 to 5V operation • -33 to +220˚C measurement range, 1 second response time $ 95 $ 95 • Size: 38(W) x 14(H) x 12(D)mm Terminal Shield to suit XC-4260 XC-4224 $16.95 See our full range of Arduino Boards, Shields, Modules and Displays in-store or check online. This special Arduino-compatible board supports the AndroidTM Open Accessory Development Kit, which is Google’s official platform for designing AndroidTM accessories. Plugs straight into your AndroidTM device and communicates with it via USB. Includes a built-in phone charger. • USB host controller chip • Phone charging circuit built in • 8 analog inputs • MicroSD memory card slot XC-4222 A tiny Arduino-compatible board that you can plug in straight into your USB port. Features a full range of analogue and digital I/O, a usercontrollable RGB LED on the board and an onboard Piezo/sound generator. • ATmega32u4 MCU with 2.5K RAM and 32K Flash • Size: 49(W) x 19(H) x 8(D)mm XC-4266 29 $ • Assembly time: 5 hours • Requires 3 x AAA batteries • Suitable for ages 8+ $ 95 • Size:105(W) x 170(L) x 125(H)mm SAVE $5 KJ-8954 was $24.95 Limited Stock. Not available online. 19 USBDroid, Arduino-Compatible with USB-host Support LeoStick (Arduino Compatible) XC-4268 $7.95 2995 $ • PCB: 101 x 41mm KC-5519 Check website for store trading hours LeoStick Shield to suit Assemble this robot and watch it dutifully follow a thick dark line before it. Refer: Silicon Chip Magazine January 2013 Suitable for general-purpose audio projects and supports microphone and electric guitar input. It uses the AN7511 audio IC to deliver 2W music power into 8 ohms from a 9 to 12V supply. Features low distortion, two inputs (mixed 1:1), mute and standby control. Power from 4 - 13.5VDC. See website for specifications. Kit supplied with silk-screened PCB, heatsink and PCB mount components. Cnr. Synnot & Wedge St. (03) 9741-8951 WE N SY AI Dark Line Tracer Kit 'The Champion' Audio Amplifier Kit with Pre-Amplifier WERRIBEE, VIC T TS NO LINE TRACER KITS NEW • PCB: 75 x 47mm KC-5518 • Kit supplied with silk-screened PCB, diecast enclosure (111 x 60 x 30mm), pre-programmed PIC and PCB mount components for four trigger/pickup options. KC-5513 O TT WA If you spend late nights and weekends creating and making gadgets then we want to hear from you. To learn more about our exciting competition visit: www.jaycar.com.au/makers Refer: Silicon Chip Magazine January 2013 Easy to build kit that reminds you when to put which bin out by flashing the corresponding brightly coloured LED. Up to four bins can be individually set to weekly, fortnightly or alternate week or fortnight cycle. Kit supplied with silkscreened PCB, black enclosure (83 x 54 x 31mm), pre-programmed PIC, battery and PCB mount components. 49 T NS Calling All Makers Garbage & Recycling Reminder Kit 95 34 69 YOUR LOCAL JAYCAR STORE - Free Call Orders: 1800 022 888 • AUSTRALIAN CAPITAL TERRITORY Belconnen Fyshwick Ph (02) 6253 5700 Ph (02) 6239 1801 • NEW SOUTH WALES Albury Alexandria Bankstown Blacktown Bondi Junction Brookvale Campbelltown WE HAVE MOVED Castle Hill Coffs Harbour Croydon Erina Gore Hill Hornsby Liverpool Maitland Ph (02) 6021 6788 Ph (02) 9699 4699 Ph (02) 9709 2822 Ph (02) 9678 9669 Ph (02) 9369 3899 Ph (02) 9905 4130 Ph (02) 4620 0084 Ph (02) 9634 4470 Ph (02) 6651 5238 Ph (02) 9799 0402 Ph (02) 4365 3433 Ph (02) 9439 4799 Ph (02) 9476 6221 Ph (02) 9821 3100 Ph (02) 4934 4911 Newcastle Penrith Port Macquarie Rydalmere Sydney City Taren Point NEW Tuggerah Tweed Heads WE HAVE MOVED Wagga Wagga Warners Bay NEW Wollongong Ph (02) 4965 3799 Ph (02) 4721 8337 Ph (02) 6581 4476 Ph (02) 8832 3120 Ph (02) 9267 1614 Ph (02) 9531 7033 Ph (02) 4353 5016 Ph (07) 5524 6566 Ph (02) 6931 9333 Ph (02) 4954 8100 Ph (02) 4226 7089 • NORTHERN TERRITORY Darwin Ph (08) 8948 4043 • QUEENSLAND Aspley Caboolture Cairns Caloundra Capalaba Arrival dates of new products in this flyer were confirmed at52  S the time of print but delays sometimes occur. Please ilicon Chip ring your local store to check stock details. Prices valid from 24th January 2013 to 23rd February 2013. NEW Ph (07) 3863 0099 Ph (07) 5432 3152 Ph (07) 4041 6747 Ph (07) 5491 1000 Ph (07) 3245 2014 HEAD OFFICE Ipswich Labrador Mackay Maroochydore Mermaid Beach WE HAVE MOVED Nth Rockhampton Townsville Underwood Woolloongabba Ph (07) 3282 5800 Ph (07) 5537 4295 Ph (07) 4953 0611 Ph (07) 5479 3511 Ph (07) 5526 6722 Ph (07) 4926 4155 Ph (07) 4772 5022 Ph (07) 3841 4888 Ph (07) 3393 0777 • SOUTH AUSTRALIA Adelaide Clovelly Park Elizabeth Gepps Cross Reynella NEW • TASMANIA Hobart Launceston • VICTORIA Cheltenham 320 Victoria Road, Rydalmere NSW 2116 Ph: (02) 8832 3100 Fax: (02) 8832 3169 Ph (08) 8231 7355 Ph (08) 8276 6901 Ph (08) 8255 6999 Ph (08) 8262 3200 Ph (08) 8387 3847 Ph (03) 6272 9955 Ph (03) 6334 2777 Ph (03) 9585 5011 ONLINE ORDERS Coburg Ferntree Gully Frankston Geelong Hallam Kew East Melbourne Ringwood Shepparton Springvale Sunshine Thomastown Werribee NEW Ph (03) 9384 1811 Ph (03) 9758 0141 Ph (03) 9781 4100 Ph (03) 5221 5800 Ph (03) 9796 4577 Ph (03) 9859 6188 Ph (03) 9663 2030 Ph (03) 9870 9053 Ph (03) 5822 4037 Ph (03) 9547 1022 Ph (03) 9310 8066 Ph (03) 9465 3333 Ph (03) 9741 8951 • WESTERN AUSTRALIA Joondalup Maddington Mandurah Midland Northbridge Rockingham Website: www.jaycar.com.au Email: techstore<at>jaycar.com.au NEW Ph (08) 9301 0916 Ph (08) 9493 4300 Ph (08) 9586 3827 Ph (08) 9250 8200 Ph (08) 9328 8252 Ph (08) 9592 8000 siliconchip.com.au PRODUCT SHOWCASE Colour front panels for Altronics kits Altronics Distributors have recently invested a significant amount of money in a new colour printer. “So what?” you ask! This printer is a bit different: it will allow Altronics to print in colour on virtually anything, including front panels. General Manager Brian Sorensen told SILICON CHIP that they will be supplying colour panels for the majority of their kits, including those in Jiffy boxes and other “off the shelf” cases. “We’re pretty excited about this,” he said. “For too long constructors have been stuck with boring, single-colour silk screened panels, even when the SILICON CHIP original design was in colour.” “Now we can reproduce the same colours used in the original design, giving Altronics kits a degree of professionalism that no other kit supplier can match.” Altronics aims to supply colour panels on all new kit production runs and introduce them into Contact: their stores as stock Altronic Distributors Pty Ltd runs low. Retail pric- PO Box 8350, Perth Busn Centre, WA 6849 es will be generally Tel: 1300 780 999 Fax: 1300 790 999 Website: www.altronics.com.au unaffected. 9.0MP Digital Pen Microscope In addition to a 9.0MP Camera, the new OiTEZ eScope Filter Pro also has a built-in adjustable polarising light filter and is supplied with powerful measurement software. With a 10X ~ 40X, and a 200X magnification the eScope Filter Pro is an innovative way to discover, capture and share microscopy. It can capture still images at a resolution of 640 x 480 through to 3488 x 2616 pixels and 15fps video with a resolution of 800x600 pixels. The powerful measurement software will measure many variations of lines, angles and circles making the eScope Filter Pro the ideal tool for use in quality control, setting up work instructions and reporting, in a multitude of industrial application. This versatile product will find a home in education and in various fields of science as well as being a useful tool for all sorts of hobbies. It has a USB interface, built in 8-LED illumination with two stage control and is supplied with software on CD and a small adjustable stand. A range of optional stands is also available. The MS1317 Contact: OiTEZ eScope FilWiltronics Research Pty Ltd ter Pro is available U/4 Cnr Ring Rd & Sturt St, Ballarat Vic 3350 from Wiltronics <at> Tel: (03) 5334 2513 Fax: (03) 5334 1845 $148.00 inc. GST. Website: www.wiltronics.com.au siliconchip.com.au It’s Show & Tell Time – and it could earn you a $100 Gift Card! Ok, you’ve put something really special together using Jaycar parts, so now it’s time to Show & Tell. Describe your design to Jaycar in 400 words or less, upload a few pics and you’ll be in the running to win one of 50 $100 Jaycar Gift Cards! They’ll also present your invention (or at least as many as space will allow) in the new 2013 Jaycar Catalog for all your friends, family and the extended Jaycar Family to see. If it’s really scathingly brilliant, your design might also be featured as a project in SILICON CHIP! Be it something simple, or something that completely automates your house, they want to know about it. You’ll find all the details and conditions of entry at www.jaycar. com.au/makers.asp. But you’ll have to be quick: entries close on February 5 so get your skates on and send your project details in NOW! February 2013  53 SERVICEMAN'S LOG Two tablets: both dropped, both fixed Laptops, smartphones & tablets can be quite easy to service, provided you can get the parts. Unfortunately, that’s not always possible but persistence often as not pays off and you have a win. I N THIS BUSINESS, advancing tech­ nology is – and always has been – a double-edged sword. The nature of servicing is constantly changing and not always for the better. Many bread and butter jobs that once kept small businesses ticking over have all but disappeared, either because new tech­ nology has rendered them obsolete (think belts and heads in VCRs) or because it’s often simply cheaper to throw a faulty item away and buy a new one. Another change I am seeing is in the spare parts area. Many previously repairable parts are now considered to be “consumables” or throwaway items, resulting in more lost service work. In the past, a phone call or an email was all it took to get virtually any part for any brand of laptop, monitor or printer, either directly from the manufacturer or from a distributor and usually at a reasonable cost. These days, however, many manu­ facturers no longer make all the parts available. And that means we are often unable to repair equipment, even where the job would otherwise be reasonably straightforward. In fact, I am seeing this more and more with laptops. Many vendors now only offer a limited range of parts and even then only imported on demand from factories in Singapore, Taiwan or China. Now while I accept that it’s not practical for big computer companies to have a fully-stocked parts department in Christchurch, at least in the past they were happy to overnight the stuff from warehouses in Auckland or Wellington, or in rare cases, from Sydney or elsewhere in Australia. That meant that I’d only have to wait a few days for parts at most, a situa54  Silicon Chip tion usually acceptable to vendors and clients alike. Now, many parts are simply no longer offered. It’s not hard to figure out why; having stacks of expensive spares sitting on warehouse shelves, sometimes for years, is not an efficient use of capital. That’s bad news, both for repair agents who rely on such work to keep their businesses ticking over and for clients whose sometimes not-very-old hardware cannot be economically repaired. And although some parts are still available, the increased cost and long lead times involved in importing them from Asia mean that it’s often uneconomical to repair a device in any case. What’s more, for many clients, long turn­around times are simply unaccept­ able, especially if the machine is used for business. Telling a client that a job will take about four weeks and cost more than half as much as a new machine doesn’t cut the mustard. Adding to this, the current popularity of tablets and smartphones is now responsible for fast-diminishing sales of PCs and laptops. And while on the surface it would make sense to diversify into repairing such items, it isn’t as straightforward as it seems. You may not need a lot of specialist kit to repair these devices but you do need to have a good general knowledge of the operating systems used and be good with the mechanical bits and pieces. Unfortunately, parts availability is also a problem with these devices. I don’t know what it’s like in other countries but in my town, buying a screen for a name-brand tablet or smartphone isn’t easy. What’s more, when you do track them down, they’re usually not Dave Thompson* Items Covered This Month • Two tablets: both dropped, both fixed • LG 42PC1DV plasma TV • Faulty mixer power supply • Standard 8-Transistor SR-H505 Radio *Dave Thompson, runs PC Anytime in Christchurch, NZ. cheap. It’s no wonder clients often walk away when told the repair cost. Nevertheless, muggins here does tackle such repairs. Just recently, for example, I had two rather challenging tablet repairs to contend with. In both cases, they were 10-inch models, one a big-name unit and the other a relatively unknown Chinese-branded machine. Both were very nice devices with capacitive touch screens and running Android 4. Their problems started out in similar fashion. Both had been dropped and the reason their respective owners wanted them repaired was simple; they were only a few months old and the owners had no insurance to cover the cost of a new machine. My challenge was to find a screen for one and a motherboard for the other. The brand-name unit had the smashed screen and an email to their NZ branch soon had me in contact with their spare parts department. Replacement screens were available but there would be a 4-week wait to get one to us here in New Zealand. I told them I’d have to get back to them once I’d talked to the client. After all, the repair would cost half the price of a new tablet once my own charges were factored in. As for the Chinese tablet, I Googled the name and model number and quickly found the manufacturer’s website. As is often the case though, this particular model wasn’t listed on the site. However, there was a contact form so I filled it in and hit the submit button. siliconchip.com.au Saving An LG 42PC1DV Plasma TV From The Tip It’s not uncommon these days for late-model LCD and plasma TV sets with relatively minor faults to be thrown on the scrap heap. A. M. of Mount Isa, Qld recently rescued an LG 101cm plasma TV from the tip and restored it to full working order. Here’s his story . . . We live in Mount Isa, Queens­ land and I’m employed as a radio technician at one of the local mines. Thanks to a great roster, I have a few days off each week to look after the house, fix broken toys, do other repairs and spend time on several hobbies, including repairing defunct TV sets. Fortunately, a modern plasma or LCD TV is fairly straightforward to repair in many respects, assuming that the screen is OK. One particular set that I tackled recently was an LG 42PC1DV, a rather nice 2006 101cm high-definition plasma which I acquired from the local tip. It’s really not unusual to find such sets there. One of the unfortunate realities of living so far out west is that no-one repairs TVs for a living. This means that by the time you freight one somewhere, a repair quickly becomes uneconomical, especially when many manufacturers price replacement boards in the $200 region. Add in the cost of labour and it’s no wonder that most people discard a faulty set and go for the new option. Anyway, after getting the LG plasma home, I quickly set it up on the workbench in my den and switched it on. The result was better than expected. It fired up OK but the picture was missing every second line across the screen, so only half the picture information was displayed. I removed the cover and it didn’t take long to determine that all the supply rails were within specification. The culprit was most likely one of the sustain boards and a quick check soon revealed the Z sustain board had one of its two fuses blown. So the repair would be simple – I just had to get another board. In the past, I have considered buying modules for these types of boards online. However, there’s no guarantee that your board only has siliconchip.com.au a fault in one particular module, so I usually go for a complete board. This is where I have learned to go outside the normal channels in order to get spares. Freight charges are a real problem for those living in remote areas and when you add these to the prices most local companies charge for replacement boards, the costs soon mount up. This really annoys me because it often means that sets that can easily be repaired end up on the tip. As a result, my usual trick for this type of repair is to source a board from overseas. In this case, the LG would only serve as a second set for the kids to connect their games console to, so I didn’t want to spend too much money. You can find some boards on eBay or you can buy new or secondhand boards from the Chinese site Taobao. The only drawback in the latter case is that you have to use a forwarding agency (try searching for “Taobao agent” on Google or YouTube and you will soon get the picture). Basically, Taobao is somewhat like eBay except you have to have your account in credit to buy and they mainly sell to Chinese customers. This is why you use the agent. By using your favourite browser to convert the Taobao web page to English (Google Chrome is quite good), you can usually find at least a page of vendors willing to sell you a new or secondhand board. All you have to do is type in the board number. I’ve learned a few tricks with this too. You can sort by new or used but the best indicator of who actually has stock (a lot don’t) is to arrange the listing by the number of units sold in the last month. Anyway, after a couple of emails to an agent, I was soon able to purchase a secondhand board and pay for the postage to Australia. Another tip here is to use the cheapest delivery method, usually China Post, although they do offer fairly good rates for a faster service. In this case, my board arrived around three weeks later for not much more than $50 – a bargain. In the interim, I had replaced all the capacitors on the power supply board, although this set is one of the better ones with many (but not all) of the capacitors situated well away from the heatsinks. The power supply is also located in a well-ventilated spot. There was only one thing left to do and that was to fit the new Z sustain board. That done, I nervously switched the set on and bingo, that was it. The set now came on with a perfect picture. So the new board was certainly worth the wait but of course, that’s not something you can always do in a professional repair environment – not when the customer wants the set back yesterday. However, when you are fixing something like this for yourself, the cost takes precedence over time and three weeks is really not too long to wait. Before putting the cover back on, there is one modification I like to do with these type of sets. The heatsinks on the sustain boards in most sets get quite hot, so it’s probably no wonder that they eventually fail in a hot climate. As a result, I have taken to fitting a 12V computer-style fan to them. At 12V, such fans are way too noisy but they are fine if run from a 5V rail. It’s also important to choose lowcurrent fans, so that you don’t overload the power supply. In this case, with the fans in place, the heatsinks were just warm to the touch. Once the repairs had been complet­ ed, the old LG displayed an excellent picture. All I had to do now was track down a new remote control, as the original had gone missing Obviously, a generic one would do but a genuine LG remote would be better, if only to avoid complaints from other members of the household. Another quick search online revealed an Aussie site that sells original units for a very reasonable price, so I’ve ordered one in. All in all, it wasn’t a bad win, especially considering I scored a 101cm plasma TV for less than $100. In fact, the set’s so good I’m starting to think it would look better on our bedroom wall rather than sitting in the kids’ room. February 2013  55 Serr v ice Se ceman’s man’s Log – continued After a few days and with no reply, I hit one of the bigger Chinese B2B (business-to-business) sites, a resource I am increasingly turning to in order to source hard-to-find or otherwise tooexpensive hardware for smartphones and tablets. And I was in luck because it took just a few minutes to locate a suitable motherboard. In fact, there were several vendors offering the same board, all around the same price, and most also offered free shipping which is always a bonus. I’d have to be careful though; some time ago, a client dropped in trying to source a replacement motherboard for his HP tablet computer which he had purchased in Singapore. Naturally, I steered him toward this site, thinking he’d likely find one there. Well, he did but the “brand new” motherboard he ordered and received turned out to be a shabbily-refurbished one that didn’t work when assembled into the chassis. He and the vendor ended up email-sparring but he didn’t get very far – an all-too typical story sadly. Of course, I got a running commentary of this saga and was left with the feeling that somehow everything was my fault for suggesting the site in the first place. On the other hand, I’ve purchased a lot of items from many different vendors via this website without problems. My philosophy is that as long as you exercise due diligence with potential sellers and trust your instincts, then you won’t often go wrong. Besides, there is an internal payment system which withholds any funds from the vendor until you receive and are satisfied with the goods. So if things go wrong, you will eventually get your money back – as long as you pay via that system. Anyway, I found a vendor who seemed OK and purchased the motherboard. It arrived within 10 days and went straight in. After soldering the battery and WiFi antenna leads, it powered on and ran like a dream. The Servicing Stories Wanted Do you have any good servicing stories that you would like to share in The Serviceman column? If so, why not send those stories in to us? We pay for all contributions published but please note that your material must be original. Send your contribution by email to: editor<at>siliconchip.com.au Please be sure to include your full name and address details. 56  Silicon Chip cost of the motherboard was US$45.00, leaving a suitable margin for yours truly and giving the client an affordable repair. In the event, he was over the moon, so in cases like this, it is well worth offering this type of repair. What’s more, I’ve found that once you build a rapport with the suppliers and purchase a few items from them they will usually look after you from then on. Getting back to the brand-name tablet with the smashed screen, I got hold of the client and broke the bad news. The cost of the screen was such that I didn’t have the heart to add any mark-up on it. Instead, if he did go for it, I’d be happy to simply charge for the half-an-hour’s labour it would take to do the job. After some discussion, he gave me the go-ahead but I could tell he wasn’t happy about it. It didn’t seem to matter that I was offering the screen at cost plus GST. Instead, I had the feeling that he thought I was piling a huge margin on top of the screen price and trying to baffle him with “BS” when in fact I was doing him a favour. Unfortunately, you just can’t win in a case like this. Once I’d done the repair, I’d make only a small amount that likely wouldn’t even be enough to cover the time I’d invested in the job. What’s more, I’ll probably then never see this client again because he thinks he’s being “got at”. Anyway, the new screen arrived in 13 days and it took just 20 minutes to fit it and check the unit out. The screen literally pops out once two screws have been removed from the bottom of the tablet housing and it’s then just a matter of unplugging a couple of ribbon cables and plugging them into the new screen which is then easily clipped back into place. Having done this, I powered it up and made sure it was all working OK. This type of repair is easy but in this case, the cost and time involved in sourcing the parts caused problems. The client seemed to be satisfied with the results – after all, his near-new tablet was working perfectly again and carried a decent repair warranty. But again I got the impression he thought I’d diddled him. Such is the nature of the service industry! Under the pump Now for a complete change of subject. The advantage of having a dad siliconchip.com.au who was a serviceman is that when he retires, you find yourself picking up some of his work. Well, my dad wasn’t strictly a serviceman but as the neighbourhood “fix-it” guy, he ended up working on some weird and wonderful things. I was at his house the other day and he asked me if I had time to look at something a neighbour had dropped off for him to fix. To be honest, I was surprised he’d taken the job on; his sight is failing and he simply can’t put his skills (or his workshop) to good use any more. In fact, each time I visit him, I always seem to leave with a few more of his tools! This time he had a small, electronic breast milk pump to look at (don’t ask), which he said was working after he’d replaced a burned-out 12V plugpack power supply. However, when he returned it, the owner then reported intermittent problems with the power button. The pump subsequently came back but Dad couldn’t go much further with it, so I said I’d have a look. Two screws and several very tight plastic clips held it all together. Once these had been removed, I found that one end of the case held a kind of combined reservoir and pump unit while the other housed a small PCB. Aside from a bunch of surface-mount components, the board boasted just three microswitches – one for power on/off and one each for pump speed up and down. There were also four rectangular LEDs to indicate the pump speed. I could see right away what the problem was – the internal tank seal had leaked and the PCB and its switches were liberally coated in a fine white powder. The seal was easy enough to fix – a new o-ring from my spare parts box soon had that sorted but the board was a real worry. I removed it and gave it a blow out with compressed air, followed by a scrub with my fibreglass-bristle PCB brush. It cleaned up OK but the switches still looked rather dodgy. Fortunately, I had a strip of identical microswitches in stock, so I simply replaced them all and reassembled the pump. A quick test showed it to be working OK (again, don’t ask!) and the owner subsequently reported it as being as good as new. I love service work! Faulty mixer power supply As can be imagined, equipment reliability is critical in a TV studio. This next story from B. T. of Bonogin, Qld describes what happened some years ago when a mixer failed at a critical moment in a TV station. It also tells of the precautions they took to ensure it wouldn’t happen again . . . The old Channel 7 building at Epping in Sydney (now unfortunately reduced to rubble and replaced with an apartment complex) contained two large studios and several smaller studios. Each of the large studios was equipped with a 36-channel Neve analog (naturally) audio mixer. These were, when purchased in the early 1970s, the epitome of the audio mixer maker’s art. The 36 input channels in these mixers consisted of two modules: an amplifier/equaliser module and a switching module. All the amplifiers in these modules (and in the output modules, etc) were operated in class-A and built using discrete components, so the power requirements were substantial. As a result, the power supply was built in the traditional English manner; that is, like a battleship. It consisted of a 6-unit rack box containing a power transformer that would not be out of place in a welder, a bank of computergrade electrolytic capacitors and a couple of PCBs which accommodated the smaller components. The circuit itself was a fairly traditional linear regulator that supplied 24V at 20A. The pass element consisted of six 2N3055 transistors in parallel and the circuit included over-current shutdown and over voltage protection. The front of the rack-mounting box was completely blank. There were no lights, switches, maker’s name or doodads – just a military-style khaki panel. The whole thing weighed about 20kg. The two mixers quietly went about their business for many years and every­one forgot about them until one day, about half an hour before the Sydney evening news, the mixer in the news studio suddenly went dead. Extreme panic quickly set in and the duty technicians were called in to see if the problem could be fixed. They Australia’s Lowest Priced DSOs Shop On-Line at emona.com.au Now you’ve got no excuse ... update your old analogue scopes! Whether you’re a hobbyist, TAFE/University, workshop or service technician, the Rigol DS-1000E guarantee Australia’s best price. RIGOL DS-1052E 50MHz RIGOL DS-1102E 100MHz 50MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling 512k Memory Per Channel USB Device & Host Support 100MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling 512k Memory Per Channel USB Device & Host Support ONLY $ 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 362 Adelaide Tel 08 8363 5733 Fax 08 8363 5799 inc GST Perth ONLY $ Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au 439 inc GST EMONA February 2013  57 Serr v ice Se ceman’s man’s Log – continued Standard 8-Transistor SR-H505 Radio P. E. of Heathcote, Victoria likes spending time out in the desert and needs to keep track of recent events and even the date. The answer to this problem was to fix an old transistor radio with shortwave bands. Here’s his story . . . I inherited a Standard 8-Transistor SR-H505 radio from my father in 1980. As far as I know, this model wasn’t sold in Australia, the set in my possession having been brought back from England by my grandmother around 1960. Somewhere along the line, the set had failed and so it sat in my shed for many years. Fortunately, the batteries (three 1.5V “D” cells) had been removed before the set had been stowed away, so there was no damage from corrosion. This radio would have been quite expensive back in the 1960s. It was a top-of-the range 3-band unit (MW, SW1 & SW2) with two speakers and my Dad listened to it while he painted houses. He liked it because the batteries lasted quite a long time. So why try to get this old radio going again? Well, I like to travel to remote areas in Australia from time to time and like to keep up with the news and even find out what day it is! Don’t laugh, it’s very easy to lose duly pulled the supply out of the rack and discovered that the pre-regulator DC was there but the regulator circuit had shut down. Unfortunately, they were unable to quickly determine why, so the news bulletin had to be cancelled, there being no spare supply and insufficient time remaining to get the working supply from the other studio. After lugging the faulty supply back to the workshop, they fired it up and it worked, much to their surprise! Thinking that the small load they had on it may have caused this turnaround, they rigged up a load of large resistors and tried again but it still operated perfectly. They then did a few tests without finding any problems and left a note for the morning shift before going home. 58  Silicon Chip track of the days when you’re out in the bush and you sometimes need to know what day it is as fuel is only available from Monday to Friday in many places. A shortwave radio is handy when you are out in the desert, as car radios are useless in such conditions. So that’s what rekindled my interest in the old Standard transistor radio. A coin is all that’s needed to undo the single screw that secures the back in place. When I did this, it was immediately apparent that the foam that’s used to hold the battery pack and antenna in place had disintegrated. It was also very dusty inside the set but otherwise it was in good physical shape. Removing the PCB wasn’t going to be so easy and so before doing this, I took careful note of where the various coloured leads went and took a series of close-up photos for good measure. That done, I removed the PCB and tested all the germanium transistors after first using some old databooks to identify their base, collector and emitter leads. They all tested OK so it was time to delve further into the works. There are lots of very small contacts in the band switch, so these were all cleaned and sprayed with The next day, there were urgent meetings and lots of worried executives and engineers. After some discussion, they decided to cancel the productions that were due in the other studio and move its working supply over to the news studio. As for me, I was given the task of fault-finding the bad supply. I soon discovered that warming up one of the small PCBs with a hair dryer caused the supply to shut down. I also discovered that this shut-down was due to the over-voltage protection circuitry being activated. This protection circuit was fairly brutal and consisted of a large SCR across the output. When triggered, this SCR shorted the output and caused the over-current circuit to shut off the pass transistors. If this failed (eg, if the pass WD40. It made no difference – there was still nothing from the set. In fact, there wasn’t even a “crackle” when the volume control was adjusted. Next on the list were the electrolytic capacitors and so I began testing these with my ESR and Low Ohms Meter. And that was it – the first one I tested was faulty and so were all the others. Installing new ones was easy as they were physically smaller than the originals. This in turn meant that I could remove some parts that had originally been mounted on the copper side of the PCB and install them on the component side, since there was now sufficient room to do this. I guess there was a steep learning curve when the Japanese first starting building these “small” transistor receivers on PCBs. This time, the radio worked but there was some crackles when the volume control was adjusted. This was fixed with some WD40 and I also did the power switch and tone control pot for good measure. Finally, because I want to use the radio in the desert, it made sense to power it from the car’s auxiliary battery. As a result, I fitted a 7805 3-terminal regulator in its battery compartment and connected this to suitable DC plug via some figure-8 cable. So the next time I’m in the desert, I’ll have no trouble keeping up with the news and figuring out what day it is! transistors shorted), a large industrial strength fuse was the last resort. No wonder that this form of overload protection was referred to as a “crowbar” circuit. It was like shorting the output with a crowbar! Anyway, the question was why was the supply shutting down when the output was sitting on exactly 24V. The answer was that the small circuit boards are not powered from the main supply but via a much more modest transformer. And as I discovered, a number of faulty electrolytics were allowing the reference for the over-voltage circuitry to go low. So it wasn’t the main output rising that was triggering the over voltage protection. Instead, it was the reference voltage falling. The operation of the over-current siliconchip.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 circuit left a bit to be desired in that once triggered, it would latch and the only way to reset it was to switch off the mains supply and wait about five minutes for the main capacitor bank to fully discharge. If you switched it back on too soon, then it was another 5-minute wait. We replaced the capacitors in the other supply as well and, for good measure, fitted a LED to each front panel so that we could see easily if the supply was operating. The two supplies were then installed in their respective studios and tested. Of course, it didn’t stop there. Having been caught once, the station decided that there had to be a “hot standby” supply for each studio. In addition, the news studio had to have a totally separate auxiliary mixer, in case all else failed. The task of designing all this was given to one of the engineers and in due course a small Shure mixer appeared. Its inputs were paralleled with the main mixer and a switch allowed the studio output to come from either the main or auxiliary units. The new supplies arrived at enormous cost and the engineer grappled with a method of switching between them, a task made more complicated by the fact that the supplies sensed the output voltage right at the mixer to compensate for any drop in the connecting cables. Getting the sensing mixed up between the two supplies would be a recipe for disaster. In the end, he settled for a simple siliconchip.com.au switch that switched the output and the sensing simultaneously between the two supplies. He also installed two mains switches that controlled the mains inputs to the supplies. This was duly demonstrated to the executives who were impressed by the fact that it was possible to switch from one supply to the other with no effect on the audio at all. A year or so later, with all this working perfectly and no incidents of any kind, one of the audio operators got a bit bored in the quiet period before the news and decided to change supplies. He switched off the main supply and watched as the mixer went dead, then switched the DC switch to the hot standby unit which instantly shut down. Now a whiter shade of pale, the operator powered up the original supply and switched back to this. It also instantly shut down. Panicky calls to the technicians resulted in many more switching attempts being made, all to no avail, In the end, the news was done using the auxiliary mixer. After the news had finished, the technicians switched on both supplies and up came the mixer, good as new. They were again able to switch between supplies with no problems. Further investigation revealed that the operator had done a completely normal test, in that it simulated what would happen if a supply really went down. Unfortunately, it transpired that if the dead mixer was then switched to a live supply, the hundreds of small 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 electrolytic capacitors inside it drew a large spike current and triggered the over-current protection. Of course, once triggered, a 5-minute wait was required before it would unlatch. This did not happen if the supply was not powered when it was connected to the mixer, as the circuitry brought up the voltage relatively slowly. As a result, the engineer was brought back and the switching panel consigned to the bin. A new arrangement was devised that used diodes to connect the two supplies to the mixer, with the sensing taken from the input to the diodes. A simple relay circuit was then devised to activate an alarm if a supply failed. This worked well, with the supply with the highest voltage running the mixer. Extensive testing proved that no combination of switching resulted in any disturbance to the mixer, unless of course they were both off. Even then, switching one on brought up the mixer perfectly. This arrangement subsequently operated without failure until the mixers were replaced with digital mixers SC some 15 years later. February 2013  59 New! Improved! More Zap for your Shekels . . . Build this JACOB’’ S LA This Jacob’s Ladder looks and sounds spectacular and is quite easy to build. As the high voltage sparks climb up the vertical wires they snap and snarl, almost as a warning for you to keep your distance! It even smells bad, as the purplish discharge generates ozone. Never mind the photo, SEE and HEAR how the Jacobs’ Ladder performs by logging on to our website at siliconchip.com.au/videos/ jacobsladder. This short video clip shows how the spark climbs up the wires to the point where it is extinguished and then it starts again at the bottom to repeat the process. It makes quite a lot of noise and does generate ozone. Mind you, while you might expect that it would generate lots of RF interference to radio reception, in practice it does not appear to be a problem, unless you have a radio in very close proximity to the unit when it is operating. 60  S 60   60   S Silicon iliconCChip hip W e described our last Jacob’s Ladder project in the April 2007 and it is still a popular project. But when we recently presented the new High Energy Ignition Module in the November & December 2012 issues, we realised that it would make an ideal Jacob’s Ladder driver and that it should have even more zing and zap than the April 2007 design. And so it has proved to be. By the way, we are aware that there are a number of mains-power Jacob’s Ladder circuits on the internet. These are very dangerous and could easily be lethal. Don’t even consider building one of those. Build ours. That’s not to say you won’t get a helluva belt off ours if you’re silly enough to touch the bitey bits when it’s running. But at least you’ll be able to learn from your mistake – you may not get that chance with a mains-powered type. Ignition module variant In essence, the Jacob’s Ladder presented here is a slight variation on the version which can be used as a self-contained ignition coil tester. Its frequency can be varied up to 75 sparks per second and the “dwell” setting can be used to vary the timing to obtain the best sparks, ie, the noisiest and most nasty! Now we are are not going to reproduce all the information on the High Energy Ignition module – if you want to read that you should refer to the November and December 2012 issues. Instead, we will give all the information which is relevant to this particular variant. So let’s have a look at the circuit of Fig.1. Microcontroller IC1 is the heart of the circuit. It drives the gate of the IGBT (insulated gate bipolar transistor), Q1. These IGBTs are used by the squillion in the ignition system of modern cars. This type of IGBT is a big improvement on the high voltage transistors used in our previous ignition systems and it can be driven directly from the output of the microcontroller via a 1kΩ resistor from pin 9 (RB3). As a result, the circuit is more efficient and very little power is dissipated. In operation, IC1’s RB3 output is alternatively switched high (to +5V) and low to turn Q1 on and off. Each time Q1 is turned on, the current builds up in the primary winding of the coil and this stores energy in the resulting magnetic field. This magnetic field collapses when when Q1 turns off and it induces a very large voltage in the secondary winding, to fire the spark plug, or in our case, to cause a big spark to jump siliconchip.com.au What is a Jacob’s Ladder? By LEO SIMPSON Jacob’s Ladder has its origins in three major religions – Christianity, Judaism and Muslim (we try to please all readers . . .). Jacob, the son of Abraham, dreamed about a “ladder” between earth and heaven with angels climbing up and down. Some references have this ladder made from flames and sparks – hence the electronic version doing the same thing. OK, no flames – but plenty of mean-sounding sparks! Physically, as our photos show, it has two parallel (or near-parallel) metal rods about 300mm long and about 30mm apart, which have such a high voltage between them that sparks jump from one to the other. As the spark is hot, the surrounding air is heated. Hot air rises, so the column of rising air pushes the sparks upward so that they appear to form the “rungs” of a ladder. ADDER across the high voltage terminals of the ignition coil. Incidentally, in the past, most ignition coils have been auto-transformers meaning that the primary and secondary windings are connected together at one end. However, many modern ignition coils are true transformers, with completely separate primary and secondary windings. The particular ignition coil we are using for the Jacob’s Ladder is from a VS series Holden Commodore. These can usually be purchased from a wrecker or via ebay (which is where we got ours). We paid $27.50 including postage. Apart from being a readily available high energy ignition coil, the Commodore unit has a further advantage in that it has two high voltage terminals and these normally drive two spark plugs in series when used in the Commodore V6 engine. In our case, the two high-voltage terminals make it very suitable for a Jacob’s Ladder. Just connect a stiff wire to each terminal and it’s done. Now back to the circuit description. In operation, IC1 monitors two separate voltages, at pin 1 & 18. REG1 LM2940CT-5 +5V OUT 100F 100nF 100nF 2 14 Vdd 3 AN2/RA2 RB7/AN6 RA3 RA0 RA4 RB1 18 AN1/RA1 RB4 100nF X1 4.0MHz 13 17 F1 10A FAST BLOW 7 22pF RB3 RB6 6 RB0 RB2 9 12 EHT COIL C OSC1 22pF 12V BATTERY 10 IC1 PIC16F88 15 11 RB5 OSC2 -E/P 16 NOTE: SEPARATE LEAD FROM COIL PRIMARY TO BATTERY POSITIVE 13.6V TVS DWELL VR1 10k +12V 1000F 25V GND 4 1 10 +12V IN 1k MCLR FREQUENCY VR2 10k The dwell period and spark rate are set by trimpots VR1 and VR2, each connected across the 5V supply. VR1 (dwell) is monitored by input AN1 (pin 18), while VR2 (frequency) is monitored by input AN2 (pin 1). The dwell is adjustable from 129µs to 26ms and is set by monitoring the voltage at TP1. However, this is not necessary. In practice, you simply tweak VR1 to give the “hottest” (ie, best looking!) spark discharge. We are using the coil/spark test mode of the software for the High Energy Ignition module. In the original circuit (November 2012) this was selected 1k G Q1 ISL9V5036P3 (IGBT) SPARK GAP: CAUTION: THIS WILL BITE! COMMODORE IGNITION COIL E 8 Vss GND 5 LM2940CT-5 ISL9V5036P3 SC 2013 JACOB'S LADDEr Fig.1: the circuit incorporates additional components to protect the regulator against peak voltages which are superimposed on the positive supply line from the battery. siliconchip.com.au C G C GND IN E GND OUT February 2013  61 This scope grab shows the Jacob’s Ladder circuit running at 76 sparks/second and a sweep speed of 5ms/div. The yellow trace shows the high voltages (around 400V peak) at the collector of the IGBT, while the green trace shows the fluctuation on the positive battery rail. The blue trace is the voltage across the transient voltage suppressor (TVS), showing that it is doing its job of protecting the regulator. 62  Silicon Chip REG1 LM2940 +5V 100F TVS VR1 10k DWELL project and will not only give a long operation time, it can be disconnected and recharged for the next zap! For longest life you could run this from a 12V car battery but they are rather heavy and difficult to lug around. And they can be messy. Building it The Jacob’s Ladder module is built on the same PCB as the ignition system, coded 05110121 and measuring 89 x 53mm. This is housed in a 111 x 60 x 30mm diecast aluminium case to give a rugged assembly. A cable gland at one of the case provides the cable entry points for the positive and negative leads from the 12V battery and the lead from the IGBT’s collector to one of the primary connections on the Commodore ignition coil. There are significantly less components required for the Jacob’s Ladder; WIRE LINK +12V 10 4MHz TO 12V BATTERY + X1 IC1 GND PIC16F88 COIL 100nF WIRE LINKS Q1 ISL9V5036P3 (UNDER) 1k TO 12V BATTERY – TO COIL PRIMARY – (COIL PRIMARY + CONNECTS DIRECTLY TO BATTERY + VIA A 10A FAST-BLOW FUSE) 1k IGNITION 12 05110121 101150 C 2012 22pF 1000F 22pF Fig.2: the Jacob’s Ladder circuit uses the electronic ignition PCB (from November 2012) but as you can see, significantly fewer components are required (hence the empty holes). Note the wiring connection for the + side of the coil primary; it connects directly to the CASE/ battery + terminal via CHASSIS a fuse. Don’t be tempted to run the PCB wiring from this fuse. Keep the wiring separate. suppressor (TVS). It clamps transient voltages to around 23V, a safe level for the regulator. As well, we have included a 1000µF 25V capacitor to provide further filtering for the input to the regulator. Even so, it is most important that the +12V line to the module must be a separate wire to the battery positive terminal, as shown on the circuit. We have added these components after twice blowing the regulator and the microcontroller while having fun (um, doing important research) with our prototype Jacob’s Ladder. REG1 also has a 100µF filter capacitor at its output, required for stable operation. By the way, note that word “battery”. Don’t even think about running this from a mains supply. A 12V SLA (sealed lead-acid) battery, as shown in the first photograph, is perfect for this 100nF with LK2 (connected to pin 12 of IC1). Since we don’t need link options, the Jacob’s Ladder version of the circuit merely has pin 12 connected to 0V, to achieve the same outcome. Trimpot VR2 is used to set the spark rate, with a range of 15-75Hz (clockwise for increased frequency). IC1 is powered from a regulated 5V supply derived using REG1, an LM2940CT-5 low-dropout regulator designed specifically for automotive use. It features both transient overvoltage and input polarity protection. H o w e v e r, e v e n t h o u g h t h e LM2940CT-5 is a rugged regulator, it needs protection from the very high transient voltages which can be superimposed on the +12V line from the battery. Hence, we have incorporated extra protection with the 10Ω series resistor and the 13.6V transient voltage This shows the same waveforms as Scope1 but with the sweep speed slowed to 50ms/div. This capatures more of the spike voltages on the supply lines. Without the input protection components, these spike voltages would be a great deal higher and would damage the regulator. Note that the spike voltages differ because each spark discharge takes a different path across the gap. VR2 10k FREQUENCY siliconchip.com.au Again, same waveforms as before but with sweep speed upped to 200µs/div. Here see the ringing of the coil primary after the main spike. The voltage is clipped to 413V by the protection limiting inside the IGBT. hence large areas of the PCB are unpopulated. The first step is to check the PCB for any defects and in the unlikely case that there are any defects, fix them. Then install the components shown in the diagram of Fig.2. If you are using a PCB supplied by SILICON CHIP, Altronics or Jaycar you will find that some of the components to be installed are Same conditions as the grab at left but with sweep speed upped again to 20µs/div. Here we see that the spike voltages across the supply lines are very fast and both are actually clipped by the scope. not as indicated on the silk-screened component layout on the top of the PCB itself. For example, the red wire from the positive terminal of the battery does not connect to the +12V pin at the top right-hand corner of the PCB. Instead it connects to the PC pin marked “Tacho” which is not being used for its original function in this Jacob’s Ladder version of the circuit. We will detail the other component variations as we go through the assembly procedure. Begin the assembly by installing the four PC stakes at the external wiring points, ie, Tacho, GND, COIL, and TP GND. Then install three short wire links. One goes in the position labelled LK2 at one end of the microcontroller, another is wired in the position for the For the Jacob’s Ladder, there are several differences in component placement to those for the electronic ignition. Follow the component overlay diagram at left and this photo rather than the (white) silk-screen component overlay printed on the PCB. siliconchip.com.au February 2013  63 M3 x 5mm SCREWS INSULATING BUSH PCB M3 NUT M3 x 6.3mm TAPPED NYLON SPACERS Q1 2 x TO-220 SILICONE INSULATING WASHERS M3 x 10mm SCREW M3 x 5mm SCREWS The completed Jacob’s Ladder in daylight, showing which bits connect to where! All the circuitry is inside the metal box, with the Holden Commodore twin ignition coil mounted on top, spaced above the box by about 15mm with the aid of a pair of precision (Coke bottle cap) spacers. These are needed to allow the wires from the circuit to connect via spade lugs under the coil. Using crocodile clips on the coil terminals allows a great deal of flexibility when positioning the vertical (spark) wires, for best visual effect. 64  Silicon Chip Fig.3: here’s how the IGBT is mounted underneath the PCB. 6.3mm Nylon spacers hold the PCB at the right height and also insulate it from the case. Two silicone insulating washers are used to insulate the IGBT from the case. 1nF capacitor adjacent to the pins 5, 6 & 7 (of the microcontroller) while the third replaces the 10µF capacitor near the original “TACHO” PC stake. These can followed by the three resistors. Follow with the IC socket, making sure it is orientated correctly but don’t install the PIC micro yet. The capacitors can go in next. Orientate the two electrolytics as shown) then install crystal X1 and trimpots VR1 & VR2. The TVS can be installed either way around as it is not a polarised device. Regulator REG1 can then go in. Be sure to fasten REG1’s tab to the PCB using an M3 x 10mm machine screw and nut before soldering its leads. IGBT mounting details Fig.3 shows the mounting details for IGBT transistor Q1. It’s secured to the base of the case, with its leads bent at right angles and passing up through the underside of the PCB. For the time being, simply bend Q1’s leads upwards through 90° and test fit it to the PCB but don’t solder its leads yet. Its tab mounting hole must be clear of the edge of the PCB, as shown in the diagrams. Then fit the PCB assembly inside the case and slide it to the left as far it will go, to leave room for Q1. The mounting hole positions for the PCB and Q1’s tab can then be marked inside the case, after which the PCB can be removed and the holes drilled to 3mm (hint: use a small pilot drill first). Deburr these holes using an oversize drill. In particular, Q1’s mounting hole must be slightly countersunk inside the case to completely remove any sharp edges. The transistor’s mounting area on the case should also be carefully smoothed using fine emery paper. These measures are necessary to prevent the insulating washers which go between Q1’s metal tab and the case from being punctured by metal swarf or by a high-voltage arc during operation. Having drilled the base, the next step is to mark out and drill the hole in the case for the cable gland. This hole is centrally located the end of the case at which the IGBT is mounted. It should be carefully reamed to size so that the cable gland is a close fit. You will also have to drill a 3mm hole for the earth connection in the other end of the case – see photos. Installing the PCB Once the case has been drilled, fit 6.3mm tapped Nylon stand-offs to the PCB’s corner mounting holes using M3 x 5mm machine screws. That done, the next step is to fasten Q1 in place. As shown in Fig.3, its metal tab is insulated from the case using two TO-220 silicone washers and an insulating bush and it’s secured using an M3 x 10mm screw and nut. Do this screw up finger-tight, then install the PCB in the case with Q1’s leads passing up through their respective mounting holes. The PCB can now be secured in place using four more M3 x 5mm machine screws, after which you can firmly tighten Q1’s mounting screw (make sure the tab remains centred on the insulating washers). Finally, use your multimeter to confirm that Q1’s tab is indeed isolated from the metal case (you must get an open-circuit reading), then solder its leads to the pads on top of the PCB. External wiring All that remains now is to run the external wiring. You will need to run three leads through the cable gland siliconchip.com.au and solder them to the relevant PC stakes for the power, coil and input trigger connections. Don’t be tempted to use mains cable for the three leads – brown, blue and green/yellow should never be used for anything but mains. The earth connection from the PCB goes to an solder lug that’s secured to the case using an M3 x 10mm screw, nut and star washer. Initial checks & adjustments Now for an initial smoke test – apply power to the unit (between +12V and GND) and use your DMM to check the voltage between the +5V PC stake and GND. It should measure between 4.85V and 5.25V. If so, switch off and insert the programmed PIC (IC1) into its socket, making sure it goes in the right way around. You can now do some more tests by connecting the car’s ignition coil between the +12V battery terminal via a 10A in-line fuse. The unit should be powered from a 12V car or motorcycle battery or a sealed lead acid battery, NOT from a mains power supply. The negative coil wire (shown in blue on the diagram) connects to the “coil” terminal on the PCB. Before connecting the +12V power, set the dwell trimpot (VR1) fully anticlockwise. Then apply power and slowly adjust VR1 clockwise. The sparks should start and gradually increase in energy with increased dwell. Stop adjusting VR1 when the spark energy reaches its maximum. You can also set the spark frequency using VR2 but we found the best result was with it set to maximum, ie, clockwise. Mounting the Commodore ignition coil We mounted the Commodore ignition coil onto the lid of the case using two M3 bolts and nuts. Since the two primary connection are recessed underneath the coil, we had to space it off the lid of the case and we used two PET soft drink bottle lids for this. Brand is unimportant – just make sure you don’t use metal caps! We made the connections to the coil primary with red crimped male spade connectors (Jaycar PT-4518). Finally, we fitted a pair of crocodile clips with screws (Jaycar HM-3025) with stiff wire, about 250mm long. You can dispense with the plastic siliconchip.com.au finger grips since the sparks jump between the crocodile clips and then climb the wires. Note how the clips fasten to the coil terminals in our photos – if you mount them the other way (ie, with the bodies closer together) you’ll probably find that the sparks jump across the crocodile clips but don’t climb up the wires. In fact, you’ll probably have to experiment somewhat with the wire positions to get the climbing action reliable. We found that very close to parallel was right. We also bent the top 10mm or so of the wires away from the ladder, as you can also clearly see in the pic. Want to use taller wires? Give it a go – but if they are too tall it becomes unwieldy. Fitting a “chimney” We also experimented with a clear plastic (acrylic?) tube over the whole ladder. This has the added advantage of creating a vertical airflow as the air inside the tube heats up. This adds to the rising spark effect. The biggest problem was finding a clear tube (a) big enough – it needs to be about 150mm inside diameter and (b) cheap enough to warrant its use. In the end, being somewhat tight in both the wallet and time departments, we gave the idea away! However, if you can find such a tube it will add to the spectacle and should also assist the spark if there is any form of breeze. We found wind impedes the climbing effect. The tube needs to be open-ended top and bottom to create the draught. An acrylic tube will also assist somewhat in keeping the zaps contained – but don’t rely on it! A thick acrylic tube should have hundreds of kilovolts of insulation but you can never be sure. The moral of the story is, keep your fingers (and anyone else’s!) away from the vertical wires. Before making any adjustments – moving the wires for a better display, for example – disconnect the battery and make sure gravity or any other force cannot accidentally make a connection when you don’t want it to! As we said earlier, accidentally touching the wires while in operation (why would anyone touch them deliberately?!!) will certainly give you some energy you didn’t know you had – and may even (perish the thought!) cause you to issue forth with naughty words! Parts list – Jacob’s Ladder 1 VS Commodore ignition coil (source from a wrecker or ebay) 1 PCB, code 05110121, 89 x 53mm 1 diecast aluminium case, 111 x 60 x 30mm (Jaycar HB5062) 1 cable gland to suit 3-6mm cable 1 transistor insulating bush 2 TO-220 3kV silicone insulating washers (Jaycar, Altronics) 1 4MHz HC-49 crystal (X1) 1 18-pin DIL IC socket 1 in-line 3AG fuse holder and 10A 3AG fuse (fast-blow) 1 solder lug 2 crocodile clips with screws (Jaycar HM-3205) 2 250mm lengths approx. 1.5mm diameter steel wire 2 red crimp spade lugs (Jaycar PT4518) 4 6.3mm tapped Nylon standoffs 8 M3 x 5mm screws 3 M3 x 10mm screws and nuts 2 M3 x 30mm screws and nuts 1 M3 star washer 4 PC stakes 1 500mm length of red automotive wire 1 200mm length of black automotive wire 1 200mm length of blue automotive wire Semiconductors 1 PIC16F88-E/P microcontroller programmed with 0511012A.hex (IC1) 1 ISL9V5036P3 ignition IGBT (Q1) (X-On; x-on.com.au) 1 LM2940CT-5 low drop out 5V regulator (REG1) (Altronics Z0592, Jaycar ZV1560) 1 13.6V transient voltage suppressor (TVS) (Jaycar ZR-1175) Capacitors 1 1000µF 25V PC electrolytic 1 100µF 16V PC electrolytic 3 100nF MKT (code: 104) 2 22pF ceramic (code: 22) Resistors (0.25W 1%) 2 1kΩ (code: brown black black brown or brown black red brown) 1 10Ω (code: brown black black gold brown or brown black black brown) 2 10kΩ mini horizontal trimpots (VR1,VR2) SC February 2013  65 Latest PC & Tablet Accessories Build It Yourself Electronics Centre Issue: February 2013 Pre-Catalogue Sale! 16 Channel UHF Wireless Mic Systems SAVE 15% 225 $ A complete wireless mic system with your choice of handheld or lapel/beltpack mic. • Plugs into existing PA systems • Crisp vocal reproduction • Ideal for clubs, restaurants & wedding ceremonies. 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Creates a high speed 802.11n 300mbps wi-fi network. Instant connection sharing for all your devices. Talk Hands Free In The Car Latest High Luminance LED Magnifying Lamps $ Create your own 3G/4G internet hotspot at home. 35 $ This splitter allows you to view one HDMI source to two monitors. New compact design. Great for cafes, pubs and clubs. • 1080p • HDCP compliant • Includes plugpack. 49 $ A 2620 SAVE 24% 25 NEW! D 2081 26.95 $ SAVE 18% 9V battery powered! $ Latest 5GHz model for reduced interference with other peripherals. Suits left & right handers. High resolution 1000dpi optical sensor. 10m range. Includes batteries. H 8181A Thousands sold! Compact Portable Mini Mixer Swing Arm LCD Monitor Bracket Powered by 9V battery or plugpack (M 9237A $17.95) this tiny mixer is perfect for karaoke or small productions. It mixes four 6.35mm mics. Robust steel case. Extends up to 335mm from the mounting surface. Ultra slimline design. 20° ball joint for tilt adjustment. Suits monitors up to 24”. 100x100mm VESA mount. Our Build It Yourself Electronics Centres... Chip »66  S Balcatta ilicon WA: 7/58 Erindale Rd » Cannington WA: 6/1326 Albany Hwy » Perth WA: 174 Roe St » Auburn NSW: 15 Short St » Springvale VIC: 891 Princes Hwy Similar brand name versions sell for over $70 Nifty Tablet Desk Stand Every iPad® owner needs one! Adjustable, universal aluminium benchtop stand for tablets & eReaders. A must have for hands free web surfing, reading recipes and watching movies. Non-slip rubber feet. SAVE 19% 20 $ *iPad for illustration purposes. H 8250 Phone Order Now On... 1300 797 007 siliconchip.com.au or shop online 24/7 at www.altronics.com.au 139 $ 49 $ 62 $ SAVE $30 D 3020 Key Features Slimline handle An excellent multi purpose soldering iron for service technicians, schools, engineers, R&D, production work etc. Japanese ceramic heating element for long life. 0.8mm tip. Burn resistant lead Durable metal case 200° - 480°C 2 year warranty .95 T 2497 Produce top quality home made boards! Iroda Maxi Pro-Torch ® Ultra high output design suits heavy duty brazing, silver soldering in plumbing & maintenance. Allows instant heat over long periods without the need for refilling - just latch on a new butane canister! Adjustable regulator and one touch piezo ignition. T 2418 Micron® 80W Digital Soldering Station Top Value Consumables BONUS DEAL SAVE 22% 2-In-1 DMM & LAN Tester. Autoranging multimeter provides, current, voltage and resistance with max/data hold functions. LAN tester quickly tests lead integrity. Includes terminator, test leads, adaptors & carry case. SAVE 23% 24 $ H 0770 No Fuss PCB Press ‘n Peel Film AS EASY AS 1, 2, 3! 1. Photocopy/laser print. 2. Iron onto your PCB. 3. Etch your new board! Pack of 5 A4 size sheets. FREE! 4 pack of gas valued at $10.95 (T 2455). D-I-Y parts, moulds & brackets SAVE 22% 8 $ .95 H 6800 Stock Up The Tool Box With These Great Savings... T 2169 49 $ 17.95 $ 17pc Ratchet Driver Tool Kit This ultra compact ratchet kit is ideal for working in tight spaces inside equipment. Supplied with: •#1, #2 phillips • #1, #2 pozidrive • T10, 15, 20 torx • 4, 5 & 6mm flat blade • 5, 6, 7, 8, 9, 10mm 1/4” drive hex sockets. NEW! X 0215 NEW! T 2327 10 x #0 T 2328 10 x #1 T 5020A 49.95 $ Great for electricians SAVE 20% 15 $ Q 3002 Detect Lethal AC Voltages Without Contact Non-contact AC detector with LED light. Essential for working with AC wiring. Lights up when near any AC source (100-600V <at> 50-60Hz). Fits right in your pocket. SAVE 24% 30 $ T 2595 Iron Only SAVE 24% 45 $ Sturdy Aluminium Tool Case NEW! 11.95 $ T 3188 Got a board that’s gone wrong? Repair and rework solder masks with this hard permanent PCB coating. Protects and insulatea PCB tracks and components. 15ml. NEW! 15.95 $ Handy time saver! 159 $ NEW! H 1617 29 $ T 2251 .95 T 1480 Excellent accuracy down to ±3mm Must have for servicing! Squeezy Blow Brush Get an accurate distance measurement in seconds! This laser tape measure provides an instant ‘one touch’ measurement - up to 30m. Plus calculation modes such as add, subtract, pythagorean, square & cubic measurements. Great for quick removal of dust and debris from inside equipment & keyboards. Supplied fine point & brush nozzles. NEW! 8 Repair Solder Masks Instantly SAVE $40 $ .95 14x Mini Magnifier Q 1026 SAVE 15% 9 $ .95 38 $ T 2191 Stubby Ratchet Driver Small, yet powerful cordless soldering iron for quick electronic repairs. 30 min use from a full tank. T 2595 kit also includes: • Blow torch • Hot air blower • Hot knife • Solder • Sponge • Plastic carry case A must have for the glovebox or kitchen drawer! This little driver houses 7 bits, ready when you need it. *Colour may vary. Express Order Hotlines: Back by popular demand! Ideal for observing constantly varying quantities such as cycling voltages or speaker resonance testing. Features: • 10A DC current • 20kΩ/Volt sensitivity • Transistor tester • Mirrored scale • Includes test leads. Phone: 1300 797 007 Fax: 1300 789 777 www.altronics.com.au NEW! 12.50 $ T 1326 Ammonia Free T 1328 Heavy Duty Ammonia High Temperature Tape Analogue Multimeter Handyman 70W Gas Soldering Iron Ideal for bonding heatsinks to chips, CPU’s, high power displays. Note: not designed as a replacement for heatsink compound. 100gm. These tip tinners maintain your soldering iron tips for best performance! Ideal for servicing and production use. T 1326 ammonia free model suits regular tip maintenance, whilst the heavy duty T 1328 ammonia type is for recovery of blackened oxidised tips. Get a close up view! Great for PCB track inspection. NEW! Bond Devices To Heatsinks Maintain & Repair Your Iron Tips NEW MODEL! T 1470 T 2596 Kit siliconchip.com.au .95 10pc packs of commonly used (and worn out!) #0 & #1 Philips bits. 50mm length. Tools not included. 5W LED Aluminium Adjustable Torch Super tough aluminium case! 300 Lumens output. Flashing mode and adjustable beam width. Requires 3xD batteries. 335mm long. 19 $ Top Notch Driver Bit Packs Aluminium panels, reinforced corners & seams for serious protection! Locking latches. Size: 460 x 325 x 150mm. Tough, yet light weight aluminium case Add hot water to make your own custom plastic parts with this amazing granulated plastic! Once it cools down it stays rock hard and can be remoulded in hot water if required. 100g. 10pc bulk buy! SAVE 24% NEW! Make custom parts in minutes! Commonly used in solder screening and wave soldering. 33m. Part NEW! 8mm Width T 2971 $10.50 12mm T 2973 $12.95 16mm T 2974 $14.25 24mm T 2975 $18.50 NEW! February 2013  67 BUILD IT YOURSELF ELECTRONICS CENTRE Top Camera Deals! S 9902A pictured. 539 Now with remote smartphone monitoring $ SAVE $60 S 9121A Just add a hard drive and go! 0 lux Great size for a small business or family home. Simply add a hard drive (see right) and plug it in! Each pack includes: • 4 channel H.264 digital video recorder • 4 pro grade cameras • 4 x 20m BNC & power combo leads • Power splitter lead • Power supply • Easy to follow instructions. S 9900A includes 4 x weatherproof dome cameras. S 9901A includes 4 x weatherproof bullet cameras. S 9902A includes 2 x bullet cameras & 2 x dome cameras. Weatherproof cameras 92 $ Weatherproof design! Affordable D-I-Y CCTV Surveillance Packages 4 Channel H.264 recording SAVE 20% Live smartphone viewing 420 line resolution 3-axis adjustment Vandal Resistant IR Dome Camera Seagate® Hard Drives To Suit Motion triggering D 5513A 1TB $116 D 5515 2TB $148 Offers all metal construction for great long term outdoor use. IP66 rated with vari-focal lens and 30m IR illumination. 12V DC input SAVE $30 99 $ Professional Security & CCTV for less! See our YouTube demo’s on the website! 499 S 5272A S 9134A $ Weatherproof design! 0 lux 420 line resolution 3-axis adjustment Top Value Outdoor IR Camera SAVE $40 SAVE $120 Offers all metal construction for great long term outdoor use. IP66 rated with vari-focal lens and 30m IR illumination. 12V DC input 449 $ To buy these items separately would normally cost over $600 AEI Protector 8 Zone Alarm System ® Don’t become a crime statistic: Install one of these high quality AEI alarms yourself and save hundreds on installation costs! This comprehensive package includes S 5268 alarm system plus all accessories, cabling, PIR detectors, sirens and power supplies required for the average home or business installation. Inbuilt dialler function can ring up to 4 different phone numbers when your alarm triggers. Extra keypads S 5269 (max of 4) $67.85. Colour TFT Video Door Intercom • A safe & easy way to monitor the front door • Ultra-sharp 7” colour screen • Records photos of visitors when you’re not home • USB/SD photo, video & MP3 playback • Includes power supply, hookup cable, base station & camera unit • Remote door latching* • Expandable to 4 base stations (S 9407) & 2 cameras (S 9409). *When used with optional door S 9432 S 5272A PACKAGE INCLUDES: S 5268 8 sector alarm system S 5314A PIR motion detectors x 4 S 5445 Blue flashing strobe M 9332 16V AC earthed plugpack S 5090B 7.2Ah backup battery S 5462 Siren cover S 6122A Internal siren S 6125 External siren W 2095 Figure 8 hookup cable x 30m S 5400 Alarm stickers x 4 W 2370 6 core cable x 100m S 5160 Tamper switch S 5153 Surface mount reed switches x 2 In-Car DVR With Flip Screen GPS Synchronised to Google Maps. Ideal for fleet monitoring: trucks, coaches, vans and cars! Records 1080p high definition footage of outside of vehicle - day or night. 3” LCD flip-down monitor for easy monitoring & review. Includes 8GB micro-SD card. G-Sensor can trigger recording under heavy braking. 120 $ High resolution! 0.001 Lux Weatherproof 700 Line Resolution High Resolution Dome CCD Camera • Fully sealed metal enclosure • Day/night • M 9272B plugpack to suit $17.95. Ideal DVR trigger! SAVE $50 SAVE 28% 299 $ 33 $ S 5184 S 9133A NEW! Entryway Pressure Sensor S 9406 strike S 5385 $44.95. S 9120B SAVE $29 Interface this pressure mat into your alarm system or shop entry. Circuit closes when stepped on. 80x54cm. 189 $ High resolution! 0.001 Lux Weatherproof 700 Line Resolution High Resolution Bullet CCD Camera • Fully sealed metal enclosure • Day/night • M 9272B plugpack to suit $17.95. Added security for the family! SAVE $30 149 $ S 9344F Power all your cameras from the one box! Top value for home or business SAVE $30 99 $ S 9753B 9 Output CCTV Power Supply 4 Channel Digital Video Recorder Record directly from up to 4 cameras (up to 25 frames per second) to an internal hard drive available separately. • Direct connection to a PC via USB for access to footage • Scheduled & motion recording • Very easy to setup • H.264 compression • Includes software • Windows XP/7/Vista • 1TB hard drive to suit D 5513A $116. A central CCTV power supply providing 9 x 12VDC outputs, each at 500mA. Individually fused. Plugs into a standard mains outlet. Size: 203W x 203H x 54Dmm. Great choice for inside shops S 9116C TOP VALUE! 69 $ Colour Indoor Dome Camera • 3-axis adjustable • Low noise • M 9272B plugpack to suit $17.95 • 94Øx85mm • 0.01 lux • Vandal resistant • 420 line resolution. Our Build It Yourself Electronics Centres... 68  Silicon Chip BUILD IT YOURSELF ELECTRONICS CENTRE » Balcatta WA: 7/58 Erindale Rd » Cannington WA: 6/1326 Albany Hwy siliconchip.com.au » Perth WA: 174 Roe St » Auburn NSW: 15 Short St » Springvale VIC: 891 Princes Hwy Resellers: Exciting new DIY kit releases! K 5165 Silicon Chip 2 x 135W Class AB Amplifier Audio enthusiasts rejoice: It’s finally here! (SC Mar-May ‘12) A stunning low distortion, high power stereo amplifier designed for superb performance in any 2 channel audio system. It delivers 135W RMS per channel into 8 ohms (or 200W RMS into 4 ohms). It utilises two of the K 5154 amplifier module kits, plus power supply board, toroid, speaker protector kit, heatsinks, input and pre-amp boards & a stylish 2RU all metal chassis. Features: • 135W into 8 Ohm or 200W into 4 Ohm • Distortion levels around 0.008% • Includes all parts, boards, chassis, heatsinks and toroid • A must have for serious audio kit builders! • 10Hz - 20kHz. All metal case provides a top quality finish to your kit! 749 $ NEW MODEL Modules also available separately: K 5154 135W Amp Module $85ea K 5164 Input Module $35.95 $235 K 5166 Metal Chassis K 5167 Speaker Protection Module $24.95 K 5168 Power Supply Module $32.95 K 5169 Pre-Amplifier Module $34.95 MC5540 Power Transformer $99.95 3 Solar Powered Robots In One! NEW KIT! 9 $ .95 NEW KIT! 39.95 $ Build this kit into not one but 3 solar-powered robots! Includes detailed instructions to assemble, dismantle and re-assemble a robot, scorpion or tank from the included parts. Performs different movements when placed in the sun. A great introduction to solar electronics. No soldering required. Ages 8 and up. K 1110 Solar Grasshopper Kit A life size grasshopper with a solar panel on its back. When he’s placed in the sun, his body vibrates back and forth. Ages 8 and up. No tools, soldering or batteries required! K 1118 NEW KIT! 19.95 $ ‘Follow Me’ Robot Kit Uses four inbuilt microphones to detect sound (such as a hand clap) and moves toward it. Ages 8+. No soldering required. Requires 4 x AAA batteries (not included). NEW KIT! NEW KIT! 54 $ K 1115 .95 K 5804 NEW KIT! 89.95 $ 29 $ .95 K 6047 K 4500 Dog Blaster Kit Keeps your woofer quiet! Mains Timer Kit For Fans & Lights. (SC August ‘12) Are barking dogs keeping you up to all hours? The dog blaster hooks up to high power piezo tweeters (not supplied) and outputs an ultra high frequency sound to deter dogs from barking constantly. Note: Please use responsibly. Excessive use may actually make barking worse if the dog gets used to the noise. (SC August ‘12) This small module can save power by switching off fans or lighting after a period between 5s and 1 hour. It can also be hooked up to a mains rated push button for a timed manual activation. 5A/1250VA max rating. Note: must be installed by a licenced electrician in most states. K 9555 LED Musicolour Kit (SC October ‘12) Updated Musicolour for LED technology! A continuously changing kaleidoscope of colour changing in time to the music. Controls up to 16 strings of LEDs tuned to individual frequency bands. Great for Christmas lighting or DJ’s and parties. NEW KIT! 94.95 $ NEW KIT! 69.95 $ K 5181 ‘Classic-D’ Amplifier Module Kit (SC November ‘12) A rugged and reliable Class-D audio amplifier producing up to 250W into 4Ω. This high efficiency, high power design is ideal for building into any audio amplifier design. Class-D amps are commonplace amongst consumer equipment. Low distortion <0.01%. Based on the IRS2092 audio amplifier chip. K 5182 Optional speaker protector $19.95 59.95 $ NEW KIT! K 6029 Colour MaxiMite Kit (SC September ‘12) The new colour maxi-mite is here! Upgraded with colour VGA output, stereo audio synthesiser, real-time clock, Arduino compatible connector and 20 more I/O lines. A powerful programmable computer for innumerable logging, monitoring and switching projects. Note: SD card not included. Get the most from your solar panels with an MPPT charger. K 9550 Maximite BASIC SD Computer $89.95 (SC March ‘12) Delivers optimum charge current to your connected batteries via an in-built 3 stage charging system (bulk, absorption, float). Equalisation feature allows you to ensure all cells in a bank are equally charged. Suitable for charging 12V batteries from nominal 12V panels up to 120W (can be modified to suit 24V systems). Note: this is MKII version of this kit K 9552 Mini Maximite Module $49.95 published in March 2012 issue of Silicon Chip. Original MaxiMites Still Available B 0091 Sale Ends February 28th 2012 Altronics Phone 1300 797 007 Fax 1300 789 777 siliconchip.com.au Mail Orders: C/- P.O. Box 8350 Perth Business Centre, W.A. 6849 © Altronics 2012. E&OE. Prices stated herein are only valid for the current month or until stocks run out. All prices include GST and exclude freight and insurance. See latest catalogue for freight rates. All major credit cards accepted. WESTERN AUSTRALIA Bunbury ML Communications Esperance Esperance Communications Geraldton ML Communications VICTORIA Beaconsfield Electronic Connections Castlemaine Top End Technology Clayton Rockby Electronics Cranbourne Bourne Electronics Croydon Truscott's Electronic World Geelong Music Workshop Healesville Amazon DVDs Healesville Highett AV2PC Hoppers Crossing Leading Edge Leongatha Gardner Electronics Melton Melton Electronics & Comms. Nunawading Semtronics Preston Preston Electronics San Remo Shorelec Electrical Wholesale Somerville AV2PC Stawell David O Jones Mitre 10 Wodonga Exact Computers & Home Ent. 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Cessnock Leading Edge Electronics Cobar Cobar Electronics Deniliquin Wired Entertainment Gloucester Autolec Gloucester Grafton Downes Electronics Griffith Griffith Systems Plus Gunnedah Protronics Lithgow Leading Edge Electronics Nth RichmondCandle Power Technologies Oak Flats Oak Flats Electronics Orange Fordray Electronics Penrith Penrith Light and Sound Port Macquarie Fettel Communications Raymond Terrace Leading Edge Smithfield Chantronics Tamworth Bourke Street Electronics Taree Noeledge Systems Pty Ltd Wagga Wagga Wagga Car Radio & Hi-Fi Waterloo Herkes Electrical Supplies Wetherill Park Techtron Electronics Windang Mad Electronics Wyong Coastal Caravan And RV SOUTH AUSTRALIA Adelaide Aztronics Brighton Force Electronics Enfield Aztronics Findon Force Electronics Kadina Idyll Hours Hobbies Mt Barker Classic Lights & Electronics Port Lincoln Leading Edge Electronics NORTHERN TERRITORY Darwin Combined Communications NEW ZEALAND Christchurch - Riccarton Global PC Christchurch - Shirley Global PC (08) 9721 9800 (08) 9071 3344 (08) 9965 7555 (03) 9768 9420 (03) 5472 1700 (03) 9562 8559 (03) 5996 2755 (03) 9723 3860 (03) 5221 5844 (03) 5962 2763 (03) 9555 2545 (03) 9931 0845 (03) 5662 3891 (03) 9743 1233 (03) 9873 3555 (03) 9484 0191 (03) 5678 5361 (03) 5978 0007 (03) 5358 1205 (02) 6056 5746 (03) 6231 0111 (03) 6334 7333 (07) 3397 8155 (07) 3252 7466 (07) 4032 1710 (07) 5309 5943 (07) 4742 2590 (07) 5531 2599 (07) 4128 2037 (07) 4061 6214 (07) 4658 0500 (07) 4922 1058 (07) 4632 9990 (07) 4771 4211 (02) 9938 4299 (02) 4990 5971 (02) 6836 2962 (03) 5881 3555 (02) 6558 1600 (02) 6642 1911 (02) 6964 5933 (02) 6742 2110 (02) 6352 3333 (02) 4571 4699 (02) 4256 6120 (02) 6362 9901 (02) 4733 3333 (02) 6581 1341 (02) 4987 4909 (02) 9609 7218 (02) 6766 4664 (02) 6551 3622 (02) 6925 6111 (02) 9319 3133 (02) 9604 9710 (02) 4297 7373 (02) 4353 1100 (08) 8212 6212 (08) 8377 0512 (08) 8349 6340 (08) 8347 1188 (08) 8821 2662 (08) 8391 1133 (08) 8682 4911 (08) 8942 0644 +64 3 3434475 +64 3 3543333 Please Note: Resellers have to2013  69 pay the cost of freight and February insurance and therefore the range of stocked products & prices charged by individual resellers may vary from our catalogue. CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions will be paid for at standard rates. All submissions should include full name, address & phone number. 10Hz-100kHz Function Generator Uses MiniMaximite Display This circuit (Fig.1) uses an ICL­ 8038 waveform generator to produce sine, triangle and square wave outputs. The 8038 chip can still be obtained over the internet for just a few dollars each. A MiniMaximite is used as an embedded controller to display the frequency, period, output voltage and frequency band on a 16x2 LCD panel. The frequency of oscillation is controlled by the value of the capacitor connected to pin 10 and the values of the resistance from pins 4 and 5 to the positive supply. The resistance between pins 4 and 5 and the sweep supply is adjusted using VR2 to give a 50% duty cycle. If the duty cycle is not 50%, the peaks on the sinewave output will appear to Silicon Chip Binders REAL VALUE AT Stop your issues getting dog-eared $14.95 PLUS P & P H Each binder holds up to 12 issues H SILICON CHIP logo on spine & cover Price: $A14.95 plus $A10.00 p&p per order (inc GST). Buy five and get them postage free. Available in Australia only. Call (02) 9939 3295 & quote your credit card number. lean forwards or backwards. Four frequency bands provide a total range of 10Hz to 100kHz. Band 1 is 10-100Hz, band 2 is 100-1000Hz, band 3 is 1 kHz-10kHz and band 4 is 10kHz-100kHz, with each band having a small overlap with neighbouring bands. The bands are selected using switch S1a to connect capacitors of different values to pin 10. Switch S1b is a voltage divider connected to pin 2 of the MiniMaximite. Trimpots VR3 and VR4 control sinewave distortion. With careful adjustment of VR2, VR3 and VR4, a sinewave distortion level of 1% is achievable. The sine and triangle wave outputs are buffered by op amps IC1b & IC1a and their gains have been selected to give the same amplitudes for both waveforms of about 10V peak-to-peak output. The 8038 also has a square-wave output but it was not used as the square-wave source, for two reasons. First, the output at higher frequencies was not a good square wave. And second, the data sheet warns that using the square-wave output can cause glitches to appear on the sine and triangular outputs. Instead, the buffered sinewave output is squared up using a 4049 hex inverter. The sine, triangle and square- Jack Hollid ay is this mon th’s winner of a $150 g ift vouche Hare & Forb r from es wave outputs are connected to switch S2 and then fed to VR5a, the level control. This feeds IC3, an LM6171 wide bandwidth, high slew rate op amp. The 4.7kΩ resistor in series with pin 2 limits the bandwidth somewhat to provide less overshoot on square wave signals. VR5b tracks the position of level control VR5a and is used by the MiniMaximite to provide an approximate measure of the output level chosen. This information is displayed on the LCD panel. The square wave output from IC2b is fed to pin 11 of the MiniMaximite. Pin 11 is configured to measure frequency and this information, along with the period, is displayed on the LCD. Three significant figures are displayed for frequency on all ranges except band 1 where two significant figures are used. The 3.3V zener diode ensures that the input voltage to the MiniMaximite does not exceed a safe level. To set up, adjust VR2 for 50% duty cycle as described earlier, then adjust VR3 and VR4 for best sinewave output. Jack Holliday, Nathan, Qld. co n tr ib u ti on MAY THE BEST MAN WIN! As you can see, we pay $$$ for contributions to Circuit Notebook. Each month the BEST contribution (at the sole discretion of the editor) receives a $150 gift voucher from Hare&Forbes Machineryhouse. That’s yours to spend at Hare&Forbes Machineryhouse as you see fit - buy some tools you’ve always wanted, or put it towards that big purchase you’ve never been able to afford! 100% Australian owned Established 1930 “Setting the standard in quality & value” www.machineryhouse.com.au 70  Silicon Chip 150 $ GIFT VOUCHER Contribute NOW and WIN! Email your contribution now to: editor<at>siliconchip.com.au or post to PO Box 139, Collaroy NSW siliconchip.com.au 1 F VR4 100k +5V 3 2 10 D3 CONTRAST Vdd RS 11 D4 17 12 D5 18 13 D6 19 10M 9 D2 8 D1 35V 14 D7 20 11 4 IC1b IC1a 8 +3.3V 100nF 1.2k 7 1 IC1: LM833 100nF A K ZD1 3.3V 3.9k 91k 1 F A 470pF NOTE: PIN NUMBERS ON MINIMAXIMITE REFER TO I/O PIN NUMBERS EXCEPT WHERE STATED OTHERWISE 3.3k 6 5 2 3 LOW ESR 100 F CON2 PIN2 D0 GND R/W 7 1 5 16 x 2 LCD MODULE 6 EN 4 2 MINIMAXIMITE S1b 11 V– BAND 16 C SQ 9 OUT IC4 2 ICL8038 SIN DIST OUT 15 CON2 PIN1 1 10 220nF S1a BAND SINE DISTORTION 12 VR3 100k FM 7 BIAS 1 SIN 5 Fadj TRI 3 OUT 4 6 V+ Fadj 8 SWEEP 2.2k 20k 100nF 2.2k VR2 DUTY CYCLE ZD1 IC2c 1 K 5 6 3 +15V IC2a –15V 8 IC2f IC2e K GND OUT 1N4004 100nF A 15 12 10 1000 F 4.7k S2 MODE 1000 F +5V IN OUT 7915 100nF 100nF 100nF 2 3 100nF IN IN IN IN GND OUT REG4 7915 OUT GND GND OUT REG1 7805 GND OUT 7 IC3 K A A T1 –15V OUTPUT IN OUT 7805, 7815 GND OUT K 0V 12V 17.5V D3 1N4004 1000 F 1000 F IN A D2 1N4004 1000 F K 24V 47 D1 1N4004 TANT 10 F 6 TANT 10 F LM1117T 4 LM6171 REG3 7815 4.7k 100nF VR5a 10k LIN LEVEL GND 1000 F IN REG2 LM1117T–3.3 14 2 11 9 IC2d SQUARE SINE TRIANGLE IC2: 4049B 1000 F +3.3V IC2b 2.7k 4 7 100k 100nF +15V Fig.1: the circuit uses an ICL8038 waveform generator to produce sine, triangle and square-wave outputs, while a MiniMaximite is used as an embedded controller to display the frequency, period, output voltage and frequency band on a 16x2 LCD panel. VR6 10k CONTRAST 10k LIN VR5b LEVEL 4.7k 4.7k 4.7k 33k 220pF VR1 10k 2.2nF FREQUENCY 1k 22nF siliconchip.com.au February 2013  71 GND 230V AC Circuit Notebook – Continued +24V 1k 4.7k B 10k B 1 F E B C Q1 BC556 Q2 BC556 E B C 10k 10k 220k C C B 1 F Q7 BC546 Q9 TIP32 E 390 INPUT C E Q6 BD139 100 E 120 OUTPUT 5.6k 0V 2.2nF 100 BD139 150pF Q3 BC546 BC546, BC556 B B E C Q4 BC546 E 100 B E C 100 B B C E Q8 BC556 C B Q5 BC546 E 1k Rail-to-rail power amplifier for non-audio use 72  Silicon Chip C E C This analog amplifier was designed to drive a brushless motor in environments where low EMI is critical (rather than using a typical switchmode design) but could have a variety of applications. Essentially, it is a simplified Class-B audio amplifier which has been modified to provide better efficiency and to maximise output power from limited supply rails by allowing the output to swing over virtually the full supply range. The input signal is coupled to the base of one of the PNP differential input transistors (Q1) via a 1µF capacitor and 10kΩ bias resistor. It can be DC-coupled too but this arrangement allows you to run it from a single supply (eg, 48V DC) with the control signal referenced to ground or some other rail using a suitable rail splitter (to give a virtual ground). The differential input pair has the standard configuration but rather than use a constant current source, their emitters are simply tied to the positive rail via a 10kΩ current-limiting resistor. This would normally be unacceptable for audio since it introduces some extra distortion but in this type of application, that is unimportant. The current mirror formed by NPN transistors Q3 and Q4 automatically balances the current through Q1 and B Q2 and this improves (among other attributes) supply rejection, which may be important, depending on the stiffness of the supply. This input stage then drives Q5 (part of the “voltage amplification stage” or VAS) which has a 150pF Miller capacitor for stability. In an audio amplifier we would normally use another constant current source as its collector load for best linearity but we have again simplified that down to a single 4.7kΩ resistor. Between the two is Q6, another NPN transistor configured as a VBE multiplier which is used to bias the output stage. It is shown with fixed resistors to set the voltage across it but in practice, a trimpot would be used as it could then be adjusted to compensate for component variation and so on. A 1µF capacitor across this stage reduces the variation in bias voltage with output voltage because of the varying current through this stage during operation. The output stage is a little unusual and departs from typical Class-B practice. To get maximum swing, the transistor sourcing current into the load (Q9) must be a PNP type and the one sinking current from it (Q10) must be NPN; the opposite to that used in a typical Darlingtontype output configuration. These are E C Q10 TIP31 TIP31, TIP32 B C C E –24V driven by small signal transistors which have opposite polarity, effectively forming complementary pairs, but not in the way that such pairs are typically used in amplifiers. To swing the output positive, the input stage reduces drive to VAS transistor Q5 and thus the 4.7kΩ resistor pulls up the bases of Q7 and Q8. This turns Q7 on harder and reduces the drive to Q8. Q7 then pulls more current from the base of Q9, turning it on harder and sourcing current to the load. With Q8 turning off, so does Q10 and thus there is relatively little flow current from Q9 to Q10 (ie, quiescent current). This quiescent current is adjusted using the VBE multiplier trimpot, as usual. The 100Ω emitter resistors for Q7 and Q8 provide some local negative feedback which is critical for stability; for example, as Q7 turns on and sinks more current from Q9’s base, the voltage across its emitter resistor increases and so limits the amount of current sunk from Q9, preventing it from turning on too rapidly. These resistors also help to make the quiescent current adjustment less sensitive, for the same reason. The 1kΩ resistors between base and emitter of Q9 and Q10 speed up their turn-off and reduce their collector-emitter leakage when the other half of the amplifier is in full conduction. siliconchip.com.au Recycling a floppy drive for use as a mini polishing machine SPICE simulation shows that the extra gain in this rail-to-rail output stage makes a typical amplifier unstable regardless of the value of the Miller capacitor. So to make it stable, we are using nested feedback. This is achieved by adding the 2.2nF capacitor from the output back to the base of Q5, the VAS transistor. This provides some roll-off in the frequency response of the VAS/ output stage but it does not affect global feedback as it bypasses the input stage. While the value of this capacitor does not appear to be especially critical, its presence definitely is; simulation shows bad oscillation if it is removed. The 2.2nF value was chosen for operation at around 1kHz and if, for example, you wanted to use this amplifier to drive an ultrasonic transducer, you would need to reduce its value somewhat. At around 820pF, operation beyond 20kHz is quite feasible and the cirsiliconchip.com.au & 16 and connect them to GND, then short-circuit pins 13 & 19. Pin 21 of the BA6992 is Vcc, while pin 9 is GND. Power supply voltage is about 5-9 V (from a 7809 regulator or similar). Current consumption is up to 350mA. You will need to fit a power switch. If the modifications have been done correctly, the motor will run immediately at switch on. The strength of rotation is sufficient for grinding and polishing various small parts. For grinding, paste a circular piece of emery paper onto the rotor. For polishing, use a piece of closely woven fabric to which you can apply paste. The cuit still appears to be stable. Gain is set to 23.5 by the feedback divider, so that a 2V peak-to-peak input signal will give a full output swing with a ±24V or 48V supply. This can be altered to suit the application. The parts shown were chosen for relatively low power use (driving a ~16Ω load) but larger transistors could easily be used as long as they have sufficiently high hFE. In most applications, heatsinking will be required for Q9/Q10 and possibly also Q7/Q8, which might need to be changed to higher-power devices (eg, BD139 and BD140). Q6 would normally also be mounted on the heatsink to avoid thermal runaway. Nicholas Vinen, SILICON CHIP. photos show the various steps in this process. Note that you cannot use your polishing machine continuously. Stop every 15 minutes or to prevent overheating of the BA6692. Alexey Uskov, Vladivostok, Russia. ($50) Rail-to-Rail Amplifier Frequency Response 0 -2 Amplitude (dBr) Floppy drives are now seldom used but they can easily be recycled from old computers. I have recycled a floppy drive and now it works as a mini grinding and polishing machine for various small parts. Any floppy drive can be used and the first step is to disassemble it. Inside, you will see the board and the asynchronous motor on it. You can throw out all superfluous components except the board and the motor. On the board there is typically a BA699* chip (in my case, a BA6992) which has a 2-5-channel power driver (with internal thermal shutdown). You must short-circuit pins 1 -4 -6 -8 2.2nF 820pF -10 10 100 1k 10k Frequency (Hz) 100k 1M SPICE frequency response plot for the amplifier using two different values of nested feedback capacitors. This doesn’t tell the whole story though as the amplifier runs into slew rate limiting before it runs out of bandwidth. The practical bandwidth is around 7kHz with 2.2nF and 20kHz with 820pF. February 2013  73 Extremely accurate GPS 1pps timebase for a frequency counter Get maximum accuracy from your 12-Digit Frequency Counter using this GPS 1pps Timebase. It connects to the external timebase input of the counter and will let you achieve measurement accuracy close to that of an atomic clock. You can either build it into the frequency counter or use it as a separate module. (CERAMIC PATCH ANTENNA) 5V LK1 OUT GND GLOBALSAT EM406A GPS RECEIVER MODULE Vin Rx Tx GND 1PPS 1 1k 2 100 F 4 +5V IN 5 22k 6 10k E FASTRAX UP501 GPS RECEIVER MODULE GND Vin B/UV 1PPS SC  2013 Q2 BC328 C LK2 2.2k CON1 4 1 5 3 1PPS OUT 2 100 1 1PPS POLARITY C Q1 BC338 2.2k E 2 3 * REG1 ONLY REQUIRED FOR GPS RECEIVER MODULES REQUIRING 3.3V. USE AN LP2950-3.3 OR AN LM3940IT-3.3 4 5 6 Q1 BASE VIA 10k RESISTOR GPS 1PPS TIMEBASE LP2950-3.3 BC328, BC338 GND IN B OUT E C Fig.1: the circuit consists of the GPS receiver module itself plus a couple of transistors (Q1 & Q2) to buffer and level translate the 1Hz (1pps) pulses. Regulator REG1 is required for GPS modules that operate from 3.3V DC. A RE YOU KEEN to build the new 12-Digit High-Resolution Frequency Counter described in the December 2012 and January 2013 issues of SILICON CHIP? It’s a world-first DIY design but you will also want to get the very best accuracy to go with its 12-digit resolution. To do this, you don’t need our com74  Silicon Chip 2013 issue to publish such a device and here it is. Build it for your frequency counter and you should be able to achieve a measurement accuracy of around ±1 part in 1011! Simple circuit +3.3V B Tx 100 F 3 ALTERNATIVES Rx IN GND B (CERAMIC PATCH ANTENNA) By JIM ROWE REG1* 3.3V plex GPS-based Frequency Reference (SILICON CHIP, March-May 2007), although this can be used if you have it. If you don’t, then there’s a much simpler and cheaper approach: purchase a cheap GPS receiver with 1pps output, bung it on a small interface PCB and you get close to atomic clock precision. In fact, we promised in our January Fig.1 shows the circuit details. It looks simple but that’s because all the complex circuitry needed to receive the signals from the GPS satellites and derive the 1Hz (1pps) pulses is inside the GPS module. We are specifying either of two GPS modules which are currently available from various suppliers: the GlobalSat EM-406A module which is currently available for as little as $39.90 or the Fastrax UP501 module which is smaller but priced at $59.90. The project is also compatible with various other receiver modules, if you find the EM-406A or the UP501 hard to get. The type of GPS receiver module you’ll need is one that incorporates its own ceramic “patch” antenna for the UHF signals from the GPS satellites, while also providing an output for 1pps (pulse per second) time pulses. It can operate from a DC supply of either 5.0V or 3.3V. A few currently available modules are listed in a panel elsewhere in this article. The EM-406A has its own builtin GPS patch antenna and operates siliconchip.com.au Par t s Lis t SERIAL Tx 1PPS OUT +3.3V GND SERIAL Tx SERIAL Rx GLOBALSAT EM-406A FASTRAX UP501 Fig.2: the pin connections for the GlobalSat EM-406A and Fastrax UP501 GPS modules. Check the pin connections if you use a different module. LK1 100 F + +5V TX 5 GND 2.2k BC328 Q2 BC338 Q1 3 1PPS 100 LK2 USING EM406A GPS RECEIVER 1k + 1PPS 22k 1 UB-5 jiffy box, 83 x 54 x 31mm 1 5-pin DIN socket, PCB-mount (Altronics P1188, Jaycar PS0350) 1 5-pin DIN socket, panel mount, for frequency counter (Altronics P1178, Jaycar PS0348) 2 5-pin DIN plugs (Altronics P1150, Jaycar PP0304) 1 2-core shielded cable (Altronics W3020, Jaycar WB1504) 4 M3 x 10mm machine screws +3.3V CON1 2 GND NC Extra parts for jiffy box version FASTRAX UP501 GPS RXEMODULE MI T SP G REVIE CER 13130140 (PATCH 3 1 0 2ANT) C +V RX 6 +5V REG1 LP2950-3.3 OR LM3940IT3.3 100 F + +5V 1 TX 5 2 1PPS 4 CON1 GND GND 3 NC 2 1 Q1 RX Resistors (0.25W, 1%) 1 22kΩ 1 1kΩ 1 100Ω 1 10kΩ 2 2.2kΩ *Only if project is built inside the frequency counter **Only for a GPS module which requires a 3.3V supply +5V 4 +V 1 2 3 4 5 6 10k E MI T SP G REVIE CER 13130140 (PATCH ANT) 3102 C Capacitors 1 100µF 16V RB electrolytic (or 2 if a 3.3V supply required) All the parts fit on a PCB coded 04103131 and measuring just 66 x 46mm. Fig.3 shows the assembly details. Almost half of this tiny PCB is reserved for the GPS module itself which is usually mounted using double-sided adhesive foam. To allow for convenient connection back to the counter when it is being used remotely, we have provided space for a 5-pin mini-DIN socket (CON1) at the righthand end of the PCB. This allows you to use a cable fitted with a 5-pin DIN plug to link the GPS timebase back to the counter, at the same time providing the unit with +5V power. This socket is not needed if the PCB is fitted inside the 12-Digit Frequency Counter’s case. In this situation, the 1 2.2k GLOBALSAT EM-406A GPS RX MODULE Semiconductors 1 BC338 NPN transistor (Q1) 1 BC328 PNP transistor (Q2) 1 LP2950-3.3 (TO-92) or LM3940IT-3.3 LDO regulator** Assembly 1k LK1 to the 12-Digit Frequency Counter are positive-going? Simply because it’s the leading edges of the pulses that are locked closely to the “atomic time” provided by the GPS satellites. The counter uses the positive-going edges of the external timebase pulses to clock its main gate flipflop, so this ensures the highest measurement accuracy. 10k directly from 5V DC. It features the SiRF Star III high-performance GPS chipset, very high sensitivity and an extremely fast time to first fix (ie, from a cold start). The UP501 and other compatible GPS modules operate from 3.3V DC, so for these we have made provision for fitting a 5V-3.3V LDO (low dropout) regulator (REG1). You can use either an LP2950-3.3 regulator which comes in a TO-92 package or an LM3940IT-3.3 which comes in a TO-220 package. Apart from the power supply arrangements, there is a simple buffer and level translator for the 1Hz pulses provided by the GPS module. This uses transistors Q1 (a BC338) and Q2 (a BC328) to ensure that the 1Hz pulses fed out to the counter have a peak-to-peak amplitude of 5V, regardless of the supply voltage used by the GPS module. Link LK2 allows the 1Hz pulses to be inverted or not by the buffer, so that their “leading edges” are positivegoing regardless of their polarity out of the GPS module (some modules may output them as inverted.) Why do we need to ensure that the leading edges of the 1Hz pulses fed 5 6 BACKUP V+ 3 22k 2.2k GND 1 PCB, code 04103131, 66 x 46mm 1 GPS receiver module with in-built patch antenna & 1pps output 1 6-way SIL pin strip 2 3-way SIL pin strips 2 jumper shunts 4 M3 x 10mm untapped Nylon spacers* 4 M3 x 25mm Nylon screws* 8 M3 nuts Hook-up wire for GPS module 25 x 25mm doubled-sided adhesive foam (to secure GPS module) 1PPS OUT BC328 Q2 5 6 5 4 3 2 1 4 SERIAL Rx 4 (PATCH ANTENNA AT TOP) (PATCH ANTENNA AT TOP) 100 F Vin (+5V) 3 BC338 GND 2 2.2k 1 1PPS 100 LK2 USING UP501 GPS RECEIVER Fig.3: follow these two diagrams to build the GPS 1pps Timebase. Omit CON1 if the unit is to go inside the frequency counter’s case and omit REG1 and its 100μF output capacitor if the GPS module uses a 5V supply, eg the GlobalSat EM406A. Alternatively, fit REG1 and the 100μF capacitor for the Fastrax UP501. Don’t forget to set link LK1 accordingly. siliconchip.com.au February 2013  75 IC18 TPG 74HC00 IC12 74AC10 IC11 4012B 100nF 100nF 4093B IC17 74AC74 IC13 74AC00 4518B 100nF IC9 100nF 100nF 4518B IC7 100nF IC10 100nF 100nF 74AC163 100nF 1MHz 100nF TP2 IC14 IC16 74HC160 IC15 74AC00 100nF SEL CHAN A FREQ*/PRD 74HC244 EXT/INT TB IC19 SEL CHAN B 74HC244 VC1 6-30pF 74HC161 39pF IC24 100nF TMR1 IN 8.00MHz X1 27pF D7 5819 76  Silicon Chip 74HC373 IC23 CON4 9-12V DC IN 1s 100s 100nF GROUND +5V SUPPLY 100nF WIRES CONNECTING TO GPS MINI TIME RECEIVER PCB 100nF 1PPS PULSES PIC16F877A 10s IC22 1000s Fig.4: only three leads are required to connect the timebase module to the main PCB in the frequency counter. These leads are connected directly to the GPS timebase board if it is mounted inside the counter case or run to a panel-mount DIN socket (installed on the counter’s rear panel) if the GPS timebase is mounted in a separate case (see panel). IC6 X2 32768Hz TP4 HIGH NORESOLUTION ITULOSER HGIH COUNTER RETNUOC MAIN C 2012 DRBOARD AOB NIAM 0411 tob 121111121 140top 2102 C TP1 4060B 220k 10M 39pF VC2 6-30pF D6 4093B TP5 TPG 4148 IC8 100nF 100nF 1k D5 4148 22k CON3 EXT TB IN TPG Compatible GPS Modules The following GPS receiver modules should be compatible with this unit: • GlobalSat EM-406A: 30 x 30 x 10.5mm including patch antenna. Operates from 5V DC with a current drain of 44mA. Provides a 1pps output plus a “fix” indicator LED. Rated sensitivity -159dBm. • Digilent PmodGPS: approximately 30 x 55 x 12mm including patch antenna. Operates from 3.3V DC with a current drain of 24/30mA. Provides a 1pps output plus a “fix” indicator LED. Rated sensitivity -165dBm. • RF Solutions GPS-622R: 43 x 31 x 6mm including patch antenna. Operates from 3.3V DC with a current drain of 23/50mA. Provides a 1pps output plus a “fix” indicator LED. Rated sensitivity -148dBm/-165dBm. • Fastrax UP501: 22 x 22 x 8mm including patch antenna. Operates from 3.3V DC with a current drain of 23mA. Provides a 1pps output. Rated sensitivity -165dBm. Note that for use in this project, the GPS receiver module should have a built-in ceramic patch antenna and also provide an output for the GPSderived 1Hz pulses. Not all GPS modules currently available provide both these features. GPS PCB is linked to the counter’s main PCB using three short lengths of insulated hook-up wire. Two other components shown in Fig.3 are required only if your GPS module needs a 3.3V DC supply, rather than 5V. These are REG1 and the 100µF electrolytic capacitor connected between its output and ground. If you are using the EM-406A module (which requires 5V) and you are also mounting the receiver inside the counter box, leave out CON1, REG1 and the 100µF capacitor. Conversely, install REG1 and the 100µF capacitor if you are using the UP501 GPS module. As previously stated, LK2 must be fitted in the position that provides output pulses with positive-going leading edges (see scope grab – Fig.7). Most GPS receiver modules, including those specified here, provide 1Hz pulses with this polarity anyway, so the jumper shunt will probably need to be in the upper position; ie, so that siliconchip.com.au This view shows the GPS 1pps Timebase module mounted inside the 2.5GHz 12-Digit Frequency Counter. Note that the unit must be mounted on the lid so that it sits horizontally – important for the antenna to function effectively. the pulses are taken from the non-inverting buffer output (collector of Q2). M3 x 25mm NYLON SCREWS COUNTER BOX LID Mounting Fig.5 shows how the timebase PCB is mounted inside the counter box. This is the easiest mounting option and if you’re using the EM-406 GPS module (which is quite sensitive), it and others should be perfectly workable even if you are inside a building. There are just three connections to be run to the main counter board: 1pps signal, +5V and ground (GND). Fig.4 shows the wiring details. As you can see, the ground wire connects to the ground pin just to the right of IC6, while the +5V wire connects to a PCB via to the left of IC23. The wire carrying the 1Hz pulses from the GPS receiver connects to the righthand end of the 1kΩ resistor behind CON3. On the timebase board, the +5V lead EM-406A GPS Rx MODULE Q1 M3 x 10mm NYLON SPACERS Q2 M3 NUTS DOUBLE-SIDED ADHESIVE FOAM ATTACHING MODULE TO PCB RECEIVER PCB connects to the +5V pad, the ground wire to the GND pad, and the signal lead to the “1PPS” pad. These pads are also labelled “1”, “2” and “3” (corresponding to the pin numbers for CON1, which is left out if the timebase is mounted inside the counter case). Putting it to use There are no setting-up adjustments Fig.5: the timebase module is attached to the lid of the case on M3 x 10mm untapped Nylon spacers and secure using four M3 x 25mm Nylon screws and eight M3 nuts (four used as spacers). to make before the GPS 1pps Timebase is put to use, apart from setting jumper shunts LK1 and LK2 to suit the GPS receiver module you’re using. Jumper shunt LK1 is simply placed on the right if the module needs 5V, or on the left if it needs 3.3V. In most cases, jumper LK2 will need to be placed in the “upper” position, although there may be some GPS Table 1: Resistor Colour Codes o o o o o o siliconchip.com.au No.   1   1   2   1   1 Value 22kΩ 10kΩ 2.2kΩ 1kΩ 100Ω 4-Band Code (1%) red red orange brown brown black orange brown red red red brown brown black red brown brown black brown brown 5-Band Code (1%) red red black red brown brown black black red brown red red black brown brown brown black black brown brown brown black black black brown February 2013  77 (UB-5 JIFFY BOX) 15mm DIAMETER HOLE CUT IN END OF BOX TO ALLOW ENTRY OF DIN PLUG INTO CON1 CON1 UB-5 BOX LID EM-406A GPS Rx MODULE BOX ASSEMBLY SCREWS RECEIVER PCB Q1 Q2 M3 NUTS M3 x 10mm SCREWS Fig.6: here’s how to install the GPS 1pps timebase module in a UB-5 jiffy box. The module (with CON1 installed) mounts on the case lid. Building A Standalone 1pps Timebase Some GPS receivers may not have sufficient sensitivity to work indoors. In that case, it will be necessary to install the timebase PCB in a small utility box which can then be positioned on a window sill (or wherever) for better satellite-reception. The unit can then be connected to the counter via a cable fitted with DIN plugs at either end. Fig.6 shows how the unit is mounted inside a UB-5 jiffy box. You will need to mount DIN socket CON1 on the PCB, then attach the PCB to the case lid using four M3 x 10mm machine screws and eight nuts (four used as spacers). A 15mm-diameter hole will then have to be drilled and reamed in one end of the box, in line with the DIN socket (ie, to Fig.7: the 1Hz pulses from the timebase must have positive-going leading edges as shown on the upper trace of this scope grab. In most cases, the GPS module will provide pulses with this polarity, so link LK2 will have to go in the upper (noninverting) position. If not, then set LK2 to the lower (inverting) position. modules which need it in the lower position. If you are in doubt about this and you have access to a scope, use it to check the polarity of the 1Hz output pulses. The 100ms-wide pulses should be positive-going, as shown in Fig.7. If they’re not, the remedy is to fit LK2 to the lower position. 78  Silicon Chip Alternatively, if you don’t have a scope you can easily determine the correct position for LK2 by trial and error. Be aware that most GPS receiver modules will take some time to achieve a “fix” from the GPS satellites after they are powered up. This allow plug entry). In addition, a matching 5-pin DIN socket should be mounted on the rear panel of the counter and its terminals run to the corresponding pads on the main counter PCB. Finally, you will have to make up a suitable cable with DIN plugs to connect the two units together. This can be made up using shielded 2-core audio cable (red lead = +5V, white lead = 1pps signal and shield = GND). start-up period can be as long as 70-80 seconds, depending on the GPS module’s sensitivity, your location and the signal strength from the GPS satellites. This means that until the module does achieve a fix, the 1Hz pulses from it will either be non-existent or “free running” – ie, not locked to the GPS time reference. So don’t expect to be able to make high-accuracy measurements right from switch-on. You’ll need to wait a couple of minutes while the GPS receiver locks on to the GPS signals. While you are waiting and assuming that you have selected the External Timebase option, the 12-digit counter will not usually show any measurement. Instead, it will continue to display “SILICON CHIP” until pulses are received from the timebase. If you are impatient and don’t want to wait for the GPS 1pps timebase to achieve a fix each time you switch the counter on, there’s a remedy for this too: keep it permanently powered from a separate 5V DC plugpack. That way, the GPS-locked 1Hz timebase pulses will be available to the 12-Digit Frequency Counter whenever you want SC to use it. siliconchip.com.au 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 RADIO, TV AND HOBBIES April 1939 to March 1965 – Every article to enjoy once again on DVD-ROM! This remarkable archival collection spans nearly three decades of Australia's own "Radio and Hobbies" then Radio TV and Hobbies". Every article has been painstakingly scanned into PDF format – ready to read at your leisure on your computer (obviously, a DVD-ROM reader is required along with Acrobat Reader!). For history buffs, it's worth its weight in gold. For vintage radio    enthusiasts, what could be better? For *    anyone interested in electronics, this is one   which you MUST have in your collection! 62 SELF ON AUDIO by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 474 pages in paperback. $ 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 introduc- SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $88.00* 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 $81.00* "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. tory 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. OP AMPS FOR EVERYONE DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. By Carter & Mancini – 3RD EDITION $100.00* Substantially updates coverage for low-speed and high-speed applications, and provides step-by-step walk-throughs for design and selection of op amps. Huge 648 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. See Review March 2010 See Review Feb 2004 ELECTRIC MOTORS AND DRIVES By Austin Hughes - Third edition 2006 $51.00* Intended for non-specialist users of electric motors and drives, filling the gap between academic texts and general "handbooks". Explores all of the widely-used modern types of motor and drive including conventional & brushless DC, induction motors, steppers, servos, synchronous and reluctance. 384 pages, soft cover. USING UBUNTU LINUX by J Rolfe & A Edney – published 2007 $27.00* Ubuntu Linux is a free and easy-to-use operating system, a viable alternative to Windows and Mac OS. Introduces Ubuntu, tells how to set it up, covers the various Open Office applications and gives troubleshooting hints and tips. Highly recommended. 222 pages in paperback RF CIRCUIT DESIGN 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 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. by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2006 $61.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details siliconchip.com.au www.siliconchip. FAX (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) 2013  79 Call (02) 9939 3295 with Your order and card details to Your order to PO Box 139February Collaroy NSW 2097 with order & credit card details (02) 9939 2648 with all details Or use the handy order form on P35 of this issue ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST Premium UHF Two-Way N ot long before Christmas, we were approached by a Sydney company, HB Wireless, to look at one of their “flagship” portable UHF transceivers, the Korean-made XR-450M. According to HB Wireless, they have had a lot of success in the commercial market with this particular radio due not only to its high performance (see spec panel) but also its ruggedness. Mining and construction companies, renowned for their ability to break the unbreakable, have been some of their biggest customers. Some of the features of the XR-450M – the “lone worker” function, for example, where a worker needs to make a call within a designated time – make it particularly attractive to organisations in security industries and those in remote areas. It’s rugged, with an operating temperature range of -30 to +60°C and humidity to 95%. The fact that it covers the full land mobile band from 450MHz right up to 512MHz (many only do 450-470 or 470-490), meets military specs MIL 810C, D and E and is IP68 waterproof (more on that shortly) is also testament to the quality of this particular transceiver. Add to that its tiny size (103 x 52 x 32mm) and weight (250g with battery) – so it easily fits in the palm of your 80  Silicon Chip hand – and it’s not surprising that it has become so popular. Crowded market The “land mobile” UHF transceiver market is becoming quite crowded but is dominated by a couple of well-known brands. Breaking into this market has not been easy and, in fact, there have been casualties along the way. HB Wireless is determined not to be one of those, setting itself apart as a supplier of premium product with premium backup. They offer a two year “hot swap” replacement warranty on all portable transceivers. Waterproof We mentioned that this transceiver is IP68 waterproof a moment ago but what does this actually mean? IP68 is the highest specification under the “IP” (Ingress Protection) standard – actually an international standard EN 60529. The first of the two digits refers to intrusion protection, ranging from 0 (no special protection) up to 6 (totally dust tight). The second digit refers to moisture protection, again ranging from 0 (no protection) up to 8 (protected against prolonged effects of immersion under pressure). This means that it can be fully immersed (to a depth of five metres) and will operate as soon as it surfaces. siliconchip.com.au Radio from HB Wireless This would make the XR-450M an ideal radio for such organisations as surf lifesaving, coastal patrol, marine search and rescue etc – all of which regularly “lose” radios due to inadvertent dunking. In the vast majority of cases, especially in salt water, this is terminal for that radio. Here it is not even an inconvenience! And speaking of inconvenience, most of the organisations mentioned insist that hand-held radios are used inside a waterproof bag – which is fine until the radio is dropped in the drink and you only then find out that it has a few tiny holes! Experience? Umm . . . (Many users find the waterproof bag also tends to attenuate or muffle received signal). What else can it do? Again, we refer you to the spec panel but briefly, some of the standouts are: • 512 programmable channels in 16 groups (ideal for companies with various workgroups) • 128 x 16 dot LCD • Scramble function using frequency inversion (won’t stop a determined listener but will stop the casual “scanner”). • Built-in compander • 4.5W transmit power (on high, 2W on low); and 1W audio • Remote “stun” and “unstun” function (if the radio is stolen or lost, you can remotely disable it to prevent use/ interference/espionage). • User programmable (with appropriate software and cable); radios can be “cloned” one to another. • Ability to work as repeater (with second radio and cable). • Multi-connector compatible with the popular GP-628 plus standard. • 4.5 hour quick charge (mains charger supplied) • Meets CE, Australian/New Zealand (4294:2004), FCC and Canadian standards. With a price of $378.00 including GST and freight, the XR450M is certainly not the cheapest hand-held UHF transceiver you will find. But one with all these features? It really offers excellent value for money (particularly with the level of support offered). And while it can be programmed with UHF CB frequencies (~476MHz), this is not its market: the XR-450M is specifically aimed at the land mobile market, commercial users who demand performance and reliability. If the price tag presents a problem, HB Wireless also offer the lower-spec XR-450R (eg, no IP68, no display, covers 450512MHz, etc but otherwise similar to XR-450M) for $279.00 All transceivers come with battery, charger, USB computer connector and programming software, whip antenna, belt clip and instructions. A range of accessories is also available. HB Wireless claim the XR-450M is the strongest and highest specification radio ever sold and, while we cannot of course verify that claim, we couldn’t argue with them after playing with this little beauty. Having “played” with literally hundreds of transceivers over the years, I’d have to rate this one as right up there. (RT) Contact HB Wireless at 202 Whitford Rd, Green Valley, NSW 2168. Tel (02) 8763 7651; Web www.hbwireless.com.au SC siliconchip.com.au • Frequency range: 450 MHz ~ 512MHz • 512 channels in 16 gro ups • Nominal voltage 7.5Vol ts DC • Channel Spacing: 12.5 and 25kHz programmabl e • Coverage (open space) Up to 8km • TX up to 4.5W; low pow er 2W (switchable) • Military Specs. MIL810 C, D, E & IP68 waterpro of • 128x16 dot graphic LCD with backlight • Programmable channe l name tag • Built-in compander & voice inversion scramble r • Five-Tone,Two-Tone Enc ode & Decode • Selcall/ANI with five-to ne or DTMF • Emergency call & lone worker function • Stun/Revive, VOX, BC LO, power save & TOT • Low battery alert, signal & battery indicator • Multi-pin aux. connec tor, compatible with GP 328+ • Ergonomic design • Approvals: CE, FCC, AS /NZS 4295:2004 • Dimensions: 103mm(H) x 52mm(W) x 32mm(D) • Weight: 250g with 220 0mAh battery It’s tiny, it’s waterproof, it’s programmable, it packs a punch . . . it’s the XR-450M UHF handheld transceiver from HB Wireless. February 2013  81 Vintage Radio By Rodney Champness, VK3UG More Philips Twins – the Dutch 209U and the Australian 112A Continuing on with our series of Philips twins, this month we take a look at the Dutch Philips 209U multi-band receiver and its Australian “twin”, the model 112A. Under the skin though, these are two very different receivers. L IKE OTHER Dutch/Australian Philips twins, the 209U and 112A receivers look the same at first glance but on closer inspection, are as different as chalk and cheese. In this case though, there is a slight difference in cabinet size, so the Dutch parent company obviously produced more than one variant of this particular cabinet style with only minor differences between them. As before, the cabinet moulds for the Australian-built receiver were obtained from the parent company, probably after the parent company had finished with them. The Dutch 209U receiver was manufactured from 1946-1947 while its Australian look82  Silicon Chip alike was produced somewhat later, from 1948-1949. Model 112A circuit details Fig.1 shows the circuit details of the Australian Model 112A. It’s a fairly conventional 4-valve superhet receiver with 455kHz IF stages. As shown, the antenna signal is fed to a tuned circuit consisting of L1 and C1 and resonates at a frequency just below the broadcast band. This boosts the sensitivity of the receiver at the low-frequency end of the band, while trimmer capacitor C2 boosts the performance at the high-frequency end by feeding signal into coil L2. The signal in L1 also inductively couples into L2. Basically, the tuned antenna circuits in sets of this era and later were designed to extract the maximum amount of signal from relatively short antennas. In effect, this was done by partially tuning the antenna using fixed value components. This technique significantly improved receiver performance compared to sets using the antenna-tuned circuits of the 1920s. As an aside, to get the best performance from crystal sets, additional tuned circuits for the antenna are used. These must be capable of tuning the antenna right across the band, as in the crystal set described in the April 2007 issue. In addition, highfrequency 2-way radios must also siliconchip.com.au Fig.1: the Australian model 112A receiver is a conventional 4-valve superhet with 455kHz IF stages. Note the tuned antenna circuit. L1 & C1 boost the sensitivity at the low-frequency end of the band, while trimmer capacitor C2 boosts the sensitivity at the high-frequency end. have fully tunable antenna circuits (ie, the antenna must be tuned to the operating frequency) if they are to work efficiently. Getting back to Fig.1, the RF signal from the antenna circuit is tuned using C3 (one section of the dual tuning gang). The resulting signal, in the range from 530-1620kHz, is then applied to the signal grid of V1, an ECH35 converter. Note that no provision has been made to adjust the inductance of L2, so it cannot be peaked at the lowfrequency end of the tuning range. However, by adjusting the position of the dial pointer and adjusting the oscillator padder capacitors to suit, some peaking the set’s low-frequency performance is possible. It’s a fiddly process though and doesn’t always achieve perfect results (the article on alignment in the February 2003 issue described the techniques necessary for good results). At the other end of the band, C2 is adjusted to peak the performance at around 1500kHz. Local oscillator The local oscillator is based around V1, coils L3 and L4, the other section of the tuning gang (C4) and their associated components. The values siliconchip.com.au The view inside the model 112A receiver. The chassis is well laid out and all parts are readily accessible. of padder capacitors C8 and C9 are adjusted so that stations appear at the correct position of the dial at the low-frequency end of the tuning range, while C10 is used to do the same thing at the high-frequency end. V1’s output appears at its plate and this is coupled to a double-tuned 455kHz IF (intermediate frequency) transformer. The resulting 455kHz IF signal is fed to V2, an EBF35, where it is further amplified and then applied to another double-tuned 455kHz IF transformer. Its output is in turn fed to a detector diode in V2. The resulting audio signal from the detector appears across R8 and volume control potentiometer R9. From February 2013  83 Fig.2: the Dutch 209U receiver is also a 4-valve superhet design but with performance equivalent to a 5-valve circuit due to the dual role performed by valve B2 (see text). It’s a multi-band design and is more complicated than the Australian model 112. there, the signal is fed via C19 to the grid of V3, a 6V6GT audio amplifier stage. This stage in turn drives the loudspeaker via an output transformer (L12/L13). No negative feedback is used in the audio amplifier. Simple AGC The IF signal level at V2’s plate is greater than it is at the detector diode and this signal is also applied to the AGC diode via C14. This set has simple AGC and as soon as there is any signal (including any interference or other noise), a small AGC bias appears on the AGC diode. This is a good design feature as V2 has no standing bias and the set will normally be tuned to a station. However, it would not be considered good design practice in a communications receiver. By contrast, the converter stage (V2) does have standing bias due to the voltage across R2. Note that the converter receives just 20% of the AGC voltage applied to the IF valve due to the voltage divider formed by resistors R1 and R5. The power supply is designed to operate off voltages from 220-260VAC 84  Silicon Chip at 40-60Hz. Australia now has 50Hz mains but 40Hz was used in Western Australia for some time and 60Hz is used in the USA (although it’s doubtful that Philips exported this set to the USA). However, it was a good selling point and it’s possible that some of the home-lighting plants of the era ran at 60Hz. Power transformer The power transformer has two secondaries: (1) 6.3V for the valve heaters and dial lamps and (2) a 376V centretapped secondary for the HT (high tension). Note resistor R13 (250Ω) between the centre tap and the chassis. The voltage developed across this is fed to V3’s grid via R10 and R11 and provides a bias of -9V for this stage. Finally, resistor R12 decouples the HT supply at V3’s plate from the HT line fed to other sections of the receiver. This is good design practice as it minimises IF and audio feedback between the stages. The Dutch 209U circuit Now let’s take a look at the circuit for the Dutch 209U receiver – see Fig.2. This is a very different circuit to the one used in the 112A. It’s also a 4-valve superhet receiver but in this case, the first stage uses a UCH21 triode heptode (B2). This valve can be used as a separate pentode and triode and/or as a converter. In this receiver, it is used as both and so it has the performance of a 5-valve set. Unlike the 112A, which tunes the broadcast band only, the 209U is a multi-band receiver. The tuning ranges cover three bands: 157-400kHz long wave, 530-1600kHz medium wave (broadcast band) and 5.88-18.2MHz shortwave. In addition, this receiver is designed to work on both AC and DC mains and as such, can have a live or “hot” chassis. Hot-chassis sets are considered by most vintage radio collectors to be dangerous to work on, as any carelessness can lead to a severe electric shock or even death. In fact, they are often shunned because of this and only those who know what they are doing and are aware of the dangers should work on them That said, a receiver that uses a power transformer to isolate the siliconchip.com.au mains from the chassis can be quite dangerous too, as these may have an HT rail voltage in excess of 500V DC (ie, across the main electrolytic filter capacitors) soon after switch-on. This HT rail is also capable of delivering a fatal electric shock and so all sets need to be treated with respect, not just the hot-chassis AC/DC types. Valve heater voltages The valves used in the Dutch 209U receiver have 20V, 50V or 55V heaters, each rated at 100mA. As a result, when these are connected in series, a heater supply rail of 20 + 20 + 55 + 50 = 145V is required. Connecting a resistor or resistors in series with these heaters allows the set to be operated from 220V. If the set is to operate from 125V, the heaters are instead switched into two strings with three heaters in series on one string and the rectifier heater on the other. Series resistors are then used to reduce the voltage drop across each string to the required 125V. The necessary switching to do this is achieved via a plug-and-socket arrangement on the rear apron of the chassis. By changing the wiring to a couple of resistors in these strings, it’s also possible to run the set on either 110V or 200V. The wiring is such that when used on AC, the HT voltage is of the order of 150V. When operated from 220V, the current drain is around 100mA for the heaters plus a further 70mA for the plate and screen loads of the valves. Because this is an AC/DC receiver with a “hot” chassis, the antenna lead has a capacitor in series with it, so that no voltage appears on the antenna. There is no earth on this set; instead, it relies on the mains to effectively act as the earth. Foil plate antenna In addition to the external antenna, there is also a foil-plate antenna on the inside of the back panel of the receiver. This is also isolated by a capacitor to make sure no mains voltage appears on it. This antenna is shown at the top-left of the circuit diagram and is connected to the signal grid of the UCH21 triode-heptode converter valve (B2) via C120 and C101. When aligning the receiver, this plate antenna must be attached and the back panel fitted in place as it affects the antenna input tuning adjustments siliconchip.com.au This view of the model 112A shows just how few parts there are underneath the chassis. Note that this photo was taken before the power cord was rewired and properly clamped into position (the Earth connection was also later improved). The Dutch 209U’s chassis is more crowded than the model 112A’s and is further complicated by the band-switching arrangement at lower left. As a result, it’s the more difficult of the two sets to service. at the high-frequency end of each tuning range. As shown in Fig.2, all the antenna input coils are wired in series and various sections shorted to earth as required. At the same time, the secondaries are switched to valve B2’s signal grid, depending on the selected frequency band. The oscillator circuits are also switched as required to the triode section of the B2 converter valve. The mixed signals appear at the plate of B2 and are fed to a doubletuned 452kHz IF transformer (S51S54). However, one version of the receiver has an IF of 468kHz. Next, the resulting 452kHz IF signal is fed to the signal grid of the heptode section of valve B3 (UCH21). B3 amplifies this IF signal and it is then fed through a second double-tuned IF transformer. It then goes to the detector and AGC diodes in B5, a UBL21 duodiode-power pentode valve. The detected audio appears across resistor R12 and volume control potentiometer R11, with the signal at R11’s wiper then fed to the grid of the triode section in valve B3. The amplified signal from B3 is then fed via C83 to the pentode section of audio output February 2013  85 The Dutch 209U receiver is a hot-chassis design (ie, no power transformer), so care is required when working on this receiver – see text. stage B5. B5 in turn drives the speaker via a transformer. As with the model 112A, there is no negative feedback or tone control circuit in this receiver. Power supply The power supply is a typical AC/ DC configuration. As stated above, a number of valve heaters are wired in series and a resistor or resistors are wired in series with this heater string to bring the total voltage drop up to the applied mains voltage. Also as stated, around 145V is dropped across the heaters, so a further 75V is dropped across the series resistor for 220V operation. The rectifier valve (B6) is a UY1N, which is a half-wave type. This has C110 (22nF) wired across it to filter out mains interference and artefacts generated by the rectifier itself. The HT rail appears on B6’s cathode and is filtered by C1 (the first filter capacitor). This HT rail is fed to valve B5’s plate via the primary winding of the speaker transformer. The remainder of the receiver derives its HT supply via a HT filter made up of R1 and filter capacitor C2. Back-bias for the amplifying valves is derived from the voltage across resistor R75 (below B5). B5 receives around -8.5V but B1 and B3 receive only a portion of this due to R34, R35, R11 & R12. The bias voltage applied to valves 86  Silicon Chip B1 and B3 before AGC is applied is around -1.5V. Delayed AGC As with many other European Philips sets, the 209U receiver features delayed AGC. Both diodes in valve B5 are strapped together for the detector and AGC functions and no AGC bias is applied to the front-end of the set until the signal exceeds 0.5V at the AGC diode. In addition, the detector doesn’t function until the -0.5V bias on the diodes is overcome. This means that when tuning between stations, the set will normally be silent unless there is quite a bit of external interference. Once a received signal generates more than 0.5V at the detector/AGC diodes, the receiver bursts into life. However, if the amplified signal strength is only just greater than 0.5V at these diodes, considerable distortion will be present in the audio. In practice, the signal will either be well under 0.5V at these diodes or well above it in normal operation, so that’s not a problem. Comparing the two receivers From the circuit descriptions above, it’s obvious that these are two very different sets under the skin. Both sets have four valve envelopes, with three active stages in the 112A and four in the 209U. As a result, the Dutch 209U is the better performing receiver of the two. As previously stated, the 112A is a broadcast-band only set whilst the 209U has three bands. Europe uses both the long-wave band and the medium-wave band, whereas Australia ceased using the long-wave band in the late 1920s. And although Australia used the shortwave band from time to time, it has been used much more often in Europe. Because the 209U is an AC/DC live chassis set, the rear panel must be kept in place because contact with the chassis could prove fatal. It should be safe if the Neutral lead is the one that’s connected to the chassis but don’t depend on this. In fact, when I serviced such sets in times gone by, I always made sure that the mains plug was wired so that the chassis was “cold”, ie, with the Neutral connected to chassis. By contrast, the 112A has a conventional power transformer but you still have to be careful of the HT rail. Both sets can be easily accessed for routine serving by removing a panel on the underside of the set. However, the 112A has a lot fewer parts. The 209U has 35 capacitors and 18 resistors while the 112A has just 21 capacitors and 13 resistors. Restoration John de Haas, the owner of these two sets, restored them to working order mainly by replacing any faulty capacitors and out-of-tolerance resistors. He also found that the wiring in the 209U was in better condition than in the 112A. In fact, quite a bit of the wiring in the 112A had perished and this will have to be replaced in the near future. The valves used in these sets are as different as they can be. The valve bases in the 209U mainly use the American 8-pin lock-in base, with an octal base used for the rectifier. By contrast, the 112A receiver uses all octal valves. What I do like about the Dutch 209U receiver is the use of a UCH21 triode heptode for the converter valve (B2). As stated previously, the triode and heptode sections can be operated independently and this makes this valve quite versatile. When used as a converter, the triode grid and grid three of the heptode are strapped together at the valve socket. The service manual for the 209U is siliconchip.com.au The two sets, side by side, with their distinctive “flip-up” dial scales. Because it’s a hot-chassis design, the Dutch 209U receiver (right) must never be operated without its rear cover in place. comprehensive and all service work on the set is covered in detail. That’s probably just as well, particularly when it comes to the dial-scale stringing as this is not otherwise easy to figure out. On the other hand, the manual for the 112A is quite sparse but its circuit is easy to follow and service without much detail being provided. The cabinets of both of these sets cleaned up quite well and they are prime examples of how good a Bakelite cabinet can be made to look. Summary Both sets is capable of quite good performance although the 209U has the edge on the 112A. If you want multi- band operation, then the 209U is the only choice but there’s little to choose between them on the broadcast band. Finally, the 112A receiver is the easier of the two to service. It has far fewer parts than the 209U, doesn’t have complicated band switching and has a conventional power supply with SC a mains transformer. Radio, Television & Hobbies: the COMPLETE archive on DVD YES! NA R MO E THA URY ENT QUARTER C NICS O OF ELECTR ! Y R O T IS H This remarkable collection of PDFs covers every issue of R & H, as it was known from the beginning (April 1939 – price sixpence!) right through to the final edition of R, TV & H in March 1965, before it disappeared forever with the change of name to EA. For the first time ever, complete and in one handy DVD, every article and every issue is covered. If you’re an old timer (or even young timer!) into vintage radio, it doesn’t get much more vintage than this. If you’re a student of history, this archive gives an extraordinary insight into the amazing breakthroughs made in radio and electronics technology following the war years. And speaking of the war years, R & H had some of the best propaganda imaginable! Even if you’re just an electronics dabbler, there’s something here to interest you. • Every issue individually archived, by month & year • Complete with index for each year • A must-have for everyone interested in electronics Please note: this archive is in PDF format on DVD for PC. Your computer will need a DVD-ROM or DVD-recorder (not a CD!) and Acrobat Reader 6 or above (free download) to enable you to view this archive. This DVD is NOT playable through a standard A/V-type DVD player. Exclusive to SILICON CHIP ONLY 62 $ 00 +$10.00 P&P HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-4 Mon-Fri BY FAX:# (02) 9939 2648 24 Hours 7 Days <at> BY EMAIL:# silchip<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# PO Box 139, Collaroy NSW 2097 * Please have your credit card handy! # Don’t forget to include your name, address, phone no and credit card details. siliconchip.com.au BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information February 2013  87 SILICON CHIP PARTSHOP Looking for a specialised component to build that latest and greatest SILICON CHIP project? Maybe it’s the PCB you’re after. Or a pre-programmed micro. Or some other hard-to-get “bit”. The chances are they are available direct from the SILICON CHIP PARTSHOP. As a service to readers, SILICON CHIP has established the PARTSHOP. No, we’re not going into opposition with your normal suppliers – this is a direct response to requests from readers who have found difficulty in obtaining specialised parts such as PCBs & micros. • • • • • PCBs are normally IN STOCK and ready for despatch when that month’s magazine goes on sale (you don’t have to wait for them to be made!). Even if stock runs out (eg, for high demand), in most cases there will be no longer than a two-week wait. One low p&p charge: $10 per order, regardless of how many boards or micros you order! (Australia only; overseas clients – email us for a postage quote). Our PCBs are beautifully made, very high quality fibreglass boards with pre-tinned tracks, silk screen overlays and where applicable, solder masks. Best of all, those boards with fancy cut-outs or edges are already cut out to the SILICON CHIP specifications – no messy blade work required! PRINTED CIRCUIT BOARD TO SUIT PROJECT: AM RADIO TRANSMITTER PUBLISHED: PCB CODE: JAN 1993 06112921    Price: $25.00 PRINTED CIRCUIT BOARD TO SUIT PROJECT: PCB CODE: Price: DIGITAL SPIRIT LEVEL/INCLINOMETER PUBLISHED: AUG 2011 04108111 $15.00 $25.00 CHAMP: SINGLE CHIP AUDIO AMPLIFIER FEB 1994 01102941 $5.00 ULTRASONIC WATER TANK METER SEP 2011 04109111 PRECHAMP: 2-TRANSISTOR PREAMPLIER JUL 1994 01107941 $5.00 ULTRA-LD MK2 AMPLIFIER UPGRADE SEP 2011 01209111 $5.00 HEAT CONTROLLER JULY 1998 10307981 $10.00 ULTRA-LD MK3 AMPLIFIER POWER SUPPLY SEP 2011 01109111 $25.00 MINIMITTER FM STEREO TRANSMITTER APR 2001 06104011 $25.00 HIFI STEREO HEADPHONE AMPLIFIER SEP 2011 01309111 $30.00 MICROMITTER FM STEREO TRANSMITTER DEC 2002 06112021 $10.00 GPS FREQUENCY REFERENCE (IMPROVED) SEP 2011 04103073 $30.00 SMART SLAVE FLASH TRIGGER JUL 2003 13107031 $10.00 DIGITAL LIGHTING CONTROLLER LED SLAVE OCT 2011 16110111 $30.00 12AX7 VALVE AUDIO PREAMPLIFIER NOV 2003 01111031 $25.00 USB MIDIMATE OCT 2011 23110111 $30.00 POOR MAN’S METAL LOCATOR MAY 2004 04105041 $10.00 QUIZZICAL QUIZ GAME OCT 2011 08110111 $30.00 BALANCED MICROPHONE PREAMP AUG 2004 01108041 $25.00 ULTRA-LD MK3 PREAMP & REMOTE VOL CONTROL NOV 2011 01111111 $30.00 LITTLE JIM AM TRANSMITTER JAN 2006 06101062 $25.00 ULTRA-LD MK3 INPUT SWITCHING MODUL NOV 2011 01111112 $25.00 JAN 2006 11101061 $25.00 ULTRA-LD MK3 SWITCH MODULE NOV 2011 01111113 $10.00 APRIL 2006 01104061 $25.00 ZENER DIODE TESTER NOV 2011 04111111 $20.00 ULTRASONIC EAVESDROPPER AUG 2006 01208061 $25.00 MINIMAXIMITE NOV 2011 07111111 $10.00 RIAA PREAMPLIFIER AUG 2006 01108061 $25.00 ADJUSTABLE REGULATED POWER SUPPLY DEC 2011 18112111 $5.00 GPS FREQUENCY REFERENCE (A) (IMPROVED) MAR 2007 04103073 $30.00 DIGITAL AUDIO DELAY DEC 2011 01212111 $30.00 GPS FREQUENCY REFERENCE DISPLAY (B) MAR 2007 04103072 $20.00 DIGITAL AUDIO DELAY Front & Rear Panels DEC 2011 0121211P2/3 $20 per set KNOCK DETECTOR JUNE 2007 05106071 $25.00 AM RADIO JAN 2012 06101121 $10.00 SPEAKER PROTECTION AND MUTING MODULE JULY 2007 01207071 $20.00 STEREO AUDIO COMPRESSOR JAN 2012 01201121 $30.00 CDI MODULE SMALL PETROL MOTORS MAY 2008 05105081 $15.00 STEREO AUDIO COMPRESSOR FRONT & REAR PANELS JAN 2012 0120112P1/2 $20.00 LED/LAMP FLASHER SEP 2008 11009081 $10.00 POCKET TENS UNIT STUDIO SERIES RC MODULE 3-INPUT AUDIO SELECTOR (SET OF 2 BOARDS) JAN 2012 01101121/2 $30 per set 12V SPEED CONTROLLER/DIMMER      (Use Hot Wire Cutter PCB from Dec 2010 [18112101]) CRYSTAL DAC FEB 2012 01102121 $20.00 USB-SENSING MAINS POWER SWITCH JAN 2009 10101091 $45.00 SWITCHING REGULATOR FEB 2012 18102121 $5.00 MAR 2009 04103091 $35.00 SEMTEST LOWER BOARD MAR 2012 04103121 $40.00 INTELLIGENT REMOTE-CONTROLLED DIMMER APR 2009 10104091 $10.00 SEMTEST UPPER BOARD MAR 2012 04103122 $40.00 INPUT ATTENUATOR FOR DIG. AUDIO M’VOLTMETER MAY 2009 04205091 $10.00 SEMTEST FRONT PANEL MAR 2012 04103123 $75.00 6-DIGIT GPS CLOCK MAY 2009 04105091 $35.00 INTERPLANETARY VOICE MAR 2012 08102121 $10.00 JUNE 2009 07106091 $25.00 12/24V 3-STAGE MPPT SOLAR CHARGER REV.A MAR 2012 14102112 $20.00 UHF ROLLING CODE TX AUG 2009 15008091 $10.00 SOFT START SUPPRESSOR APR 2012 10104121 $10.00 UHF ROLLING CODE RECEIVER AUG 2009 15008092 $45.00 RESISTANCE DECADE BOX APR 2012 04104121 $20.00 APR 2012 04104122 $20.00 DIGITAL AUDIO MILLIVOLTMETER 6-DIGIT GPS CLOCK DRIVER SEPT 2009 04208091 $10.00 RESISTANCE DECADE BOX PANEL/LID STEREO DAC BALANCED OUTPUT BOARD JAN 2010 01101101 $25.00 1.5kW INDUCTION MOTOR SPEED CONTROLLER (New V2 PCB) APR (DEC) 2012 10105122 $35.00 DIGITAL INSULATION METER JUN 2010 04106101 $25.00 HIGH TEMPERATURE THERMOMETER MAIN PCB ELECTROLYTIC CAPACITOR REFORMER AUG 2010 04108101 $55.00 HIGH TEMPERATURE THERMOMETER Front & Rear Panels ULTRASONIC ANTI-FOULING FOR BOATS SEP 2010 04109101 $25.00 MIX-IT! 4 CHANNEL MIXER JUNE 2012 HEARING LOOP RECEIVER SEP 2010 01209101 $25.00 PIC/AVR PROGRAMMING ADAPTOR BOARD S/PDIF/COAX TO TOSLINK CONVERTER OCT 2010 01210101 $10.00 TOSLINK TO S/PDIF/COAX CONVERTER OCT 2010 01210102 DIGITAL LIGHTING CONTROLLER SLAVE UNIT OCT 2010 HEARING LOOP TESTER/LEVEL METER 6-DIGIT GPS CLOCK AUTODIM ADD-ON MAY 2012 21105121 $30.00 MAY 2012 21105122/3 $20 per set 01106121 $20.00 JUNE 2012 24105121 $30.00 CRAZY CRICKET/FREAKY FROG JUNE 2012 08109121 $10.00 $10.00 CAPACITANCE DECADE BOX JULY 2012 04106121 $20.00 16110102 $45.00 CAPACITANCE DECADE BOX PANEL/LID JULY 2012 04106122 $20.00 NOV 2010 01111101 $25.00 WIDEBAND OXYGEN CONTROLLER MK2 JULY 2012 05106121 $20.00 UNIVERSAL USB DATA LOGGER DEC 2010 04112101 $25.00 WIDEBAND OXYGEN CONTROLLER MK2 DISPLAY BOARD JULY 2012 05106122 $10.00 HOT WIRE CUTTER CONTROLLER DEC 2010 18112101 $10.00 SOFT STARTER FOR POWER TOOLS JULY 2012 10107121 $10.00 433MHZ SNIFFER JAN 2011 06101111 $10.00 DRIVEWAY SENTRY MK2 AUG 2012 03107121 $20.00 CRANIAL ELECTRICAL STIMULATION JAN 2011 99101111 $30.00 MAINS TIMER AUG 2012 10108121 $10.00 HEARING LOOP SIGNAL CONDITIONER JAN 2011 01101111 $30.00 CURRENT ADAPTOR FOR SCOPES AND DMMS AUG 2012 04108121 $20.00 LED DAZZLER FEB 2011 16102111 $25.00 USB VIRTUAL INSTRUMENT INTERFACE SEPT 2012 24109121 $30.00 12/24V 3-STAGE MPPT SOLAR CHARGER FEB 2011 14102111 $15.00 USB VIRTUAL INSTRUMENT INT. FRONT PANEL SEPT 2012 24109122 $30.00 SIMPLE CHEAP 433MHZ LOCATOR FEB 2011 06102111 $5.00 BARKING DOG BLASTER SEPT 2012 25108121 $20.00 THE MAXIMITE MAR 2011 06103111 $25.00 COLOUR MAXIMITE SEPT 2012 07109121 $20.00 UNIVERSAL VOLTAGE REGULATOR MAR 2011 18103111 $15.00 SOUND EFFECTS GENERATOR SEPT 2012 09109121 $10.00 12V 20-120W SOLAR PANEL SIMULATOR MAR 2011 04103111 $25.00 NICK-OFF PROXIMITY ALARM OCT 2012 03110121 $5.00 MICROPHONE NECK LOOP COUPLER MAR 2011 01209101 $25.00 DCC REVERSE LOOP CONTROLLER OCT 2012 09110121 $10.00 PORTABLE STEREO HEADPHONE AMP APRIL 2011 01104111 $25.00 LED MUSICOLOUR NOV 2012 16110121 $25.00 CHEAP 100V SPEAKER/LINE CHECKER APRIL 2011 04104111 $10.00 LED MUSICOLOUR Front & Rear Panels NOV 2012 16110121 $20 per set PROJECTOR SPEED CONTROLLER APRIL 2011 13104111 $10.00 CLASSIC-D CLASS D AMPLIFIER MODULE NOV 2012 01108121 $30.00 SPORTSYNC AUDIO DELAY MAY 2011 01105111 $30.00 CLASSIC-D 2 CHANNEL SPEAKER PROTECTOR NOV 2012 01108122 $10.00 100W DC-DC CONVERTER MAY 2011 11105111 $25.00 HIGH ENERGY ELECTRONIC IGNITION SYSTEM DEC 2012 05110121 $10.00 PHONE LINE POLARITY CHECKER MAY 2011 12105111 $10.00 USB POWER MONITOR DEC 2012 04109121 $10.00 20A 12/24V DC MOTOR SPEED CONTROLLER MK2 JUNE 2011 11106111 $25.00 1.5kW INDUCTION MOTOR SPEED CONTROLLER (NEW V2 PCB) DEC 2012 10105122 $35.00 USB STEREO RECORD/PLAYBACK JUNE 2011 07106111 $25.00 THE CHAMPION PREAMP and 7W AUDIO AMP (one PCB) JAN 2013 01109121/2 $10.00 VERSATIMER/SWITCH JUNE 2011 19106111 $25.00 GARBAGE/RECYCLING BIN REMINDER JAN 2013 19111121 $10.00 USB BREAKOUT BOX JUNE 2011 04106111 $10.00 2.5GHz DIGITAL FREQUENCY METER – MAIN BOARD JAN 2013 04111121 $35.00 ULTRA-LD MK3 200W AMP MODULE JULY 2011 01107111 $25.00 2.5GHz DIGITAL FREQUENCY METER – DISPLAY BOARD JAN 2013 04111122 $15.00 PORTABLE LIGHTNING DETECTOR JULY 2011 04107111 $25.00 2.5GHz DIGITAL FREQUENCY METER – FRONT PANEL JAN 2013 04111123 $45.00 RUDDER INDICATOR FOR POWER BOATS (4 PCBs) JULY 2011 20107111-4 $80 per set VOX JULY 2011 01207111 $25.00 SEISMOGRAPH MK2 FEB 2013 21102131 $20.00 ELECTRONIC STETHOSCOPE AUG 2011 01108111 $25.00 MOBILE PHONE RING EXTENDER FEB 2013 12110121 $10.00 GPS 1PPS TIMEBASE FEB 2013 04103131 $10.00 PCB prices shown in GREEN are new lower prices – our bulk buying savings are passed on to you! NOTE: These listings are for the PCB only – not a full kit. If you want a kit, contact the kit suppliers advertising in this issue. AND NOW THE PRE-PROGRAMMED MICROS, TOO! Some micros from copyrighted and/or contributed projects may not be available. As a service to readers, SILICON CHIP stocks microcontrollers and microprocessors used in new projects (from 2012 on) and some selected older projects – pre-programmed and ready to fly! Price for any of these micros is just $15.00 each + $10 p&p per order# UHF Remote Switch (Jan09), Ultrasonic Cleaner (Aug10), Ultrasonic Anti-fouling (Sep10), Cricket/Frog (Jun12) Wideband Oxygen Sensor (Jun-Jul12) Projector Speed (Apr11), Vox (Jun11), Ultrasonic Water Tank Level (Sep11), Quizzical (Oct11) Ultra LD Pream (Nov11) Hi Energy Ignition (Nov/Dec12) Garbage Reminder (Jan13) 6-Digit GPS Clock (May-Jun09), Lab Digital Pot (Jul10) Semtest (Feb-May12) Batt Capacity Meter (Jun09), Intelligent Fan Controller (Jul10) USB Power Monitor (Dec12) GPS Car Computer (Jan10), GPS Boat Computer (Oct10) USB MIDIMate (Oct11) PIC12F675 PIC16F1507-I/P PIC16F88-E/P PIC16LF88-I/P PIC16F877A-I/P PIC18F2550-I/SP PIC18F45K80 PIC18F4550-I/P PIC18F14K50 USB Data Logger (Dec10-Feb11) Digital Spirit Level (Aug11), G-Force Meter (Nov11) Intelligent Dimmer (Apr09) Maximite (Mar11), miniMaximite (Nov11), Colour Maximite (Sept/Oct12) Digital Audio Signal Generator (Mar-May10), Digital Lighting Controller (Oct-Dec10), SportSync (May11), Digital Audio Delay (Dec11) Level (Sep11) Quizzical (Oct11), Ultra-LD Preamp (Nov11), LED Musicolour (Nov12) dsPIC33FJ64MC802-E/SP Induction Motor Speed Controller (Apr-May12) ATTiny861 VVA Thermometer/Thermostat (Mar10), Rudder Position Indicator (Jul11) ATTiny2313 Remote-Controlled Timer (Aug10) ATMega48 Stereo DAC (Sep-Nov09) PIC18F27J53-I/SP PIC18LF14K22 PIC18F1320-I/SO PIC32MX795F512H-80I/PT dsPIC33FJ128GP802-I/SP ISL9V5036P3 IGBT to suit High Energy Electronic Ignition (Nov/Dec12) – $10.00 + p&p When ordering, be sure to nominate BOTH the micro required and the project for which it must be programmed. Other items currently in the PartShop: P&P – $10 Per order within Australia. G-FORCE METER/ACCELEROMETER SHORT FORM KIT AUG 2011/NOV 2011 $44.50 (contains PCB (04108111), programmed PIC micro, MMA8451Q accelerometer chip and 4 MOSFETS) RADIO & HOBBIES ON DVD-ROM (Needs PC to play!) n/a AMATEUR SCIENTIST VOL4 ON CD n/a $62.00 $62.00 TENDA USB/SD AUDIO PLAYBACK MODULE (TD896 or 898) JAN 2012 $33.00 JST CONNECTOR LEAD 3-WAY JAN 2012 $4.50 JST CONNECTOR LEAD 2-WAY JAN 2012 $3.45 Prices include GST and are valid only for month of publication of these lists; thereafter are subject to change without notice. *Note: P&P is extra ($10 per order in Australia). # Orders may be for mixed items (eg, you can order one PCB, or one microprocessor, or three PCBs and two microprocessors – and the P&P on any of these orders is $10.00 02/13 SILICON CHIP Order Form Your Name: Your Address: Postcode: Country: Telephone No: Fax No: Email Address: Please supply: Qty Item Description Item Price P&P Total Price $10.00 No extra P&P charge for additional items on one order – valid within Australia only. Overseas orders: please email us for P&P quote. Thank you for your order. TOTAL $A Payment options:     EFT/Bank Deposit: Silicon Chip BSB 012-243 A/C 2636-80001 Please confirm transfer by email to silicon<at>siliconchip.com.au or fax 02 9939 2648 PayPal: From your PayPal account: “Send Money” to silicon<at>siliconchip.com.au Cheque/Money Order/Bank Draft: payable to Silicon Chip (Australian dollars only) Mail to Silicon Chip, PO Box 139 Collaroy NSW 2097 Australia Credit Card (see below; Visa and Mastercard ONLY): Fax to 02 9939 2648, telephone 02 9939 3295 or mail or email to above address. If paying by Visa or Mastercard please enter your details below (we DO NOT accept Amex, Diners or other credit cards) Card No: Cardholder Name: - To eMAIL (24/7) Place siliconchip.com.au silicon<at>siliconchip.com.au Your with order & credit card details Order: - OR FAX (24/7) This form (or a photocopy) to (02) 9939 2648 with all details - / Expiry Date: Signature: OR PAYPAL (24/7) OR Use PayPal to pay silicon<at>siliconchip.com.au PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with your credit card details MAIL FOR ebruary 2013  89 This form to PO Box 139, *ALL ITEMS SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES IN AUSTRALIAN DOLLARS AND INCLUDE GST WHERE APPLICABLE. Collaroy NSW 2097 02/13 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097 or send an email to silicon<at>siliconchip.com.au Corrosion prevention in an air-conditioner Thanks for your informative article on replacement of sacrificial anodes in hot-water systems in the November 2012 issue. Another common expensive home appliance that is subject to rust is the external compressor of ducted/split air conditioners. Do you have any suggestions as to how to prevent rust here? Would “electronic” rust protection as installed in motor vehicles work? (J. F., via email). • Unfortunately, you cannot use sacrificial anodes for protecting structures that are not at least partially immersed in water, eg, boats. You have to rely on primary methods such as galvanising and paint. In fact, we were recently concerned about the large split aircon system which serves the SILICON CHIP offices as it was starting to look a bit tired, even though it is serviced every six months. To that end, we had the rusting screws replaced with stainless steel screws and then had the cabinet painted (at the same time as the roof of the building). We do not think electronic rust protection systems in cars actually work. They are often sold and fitted to new cars but modern cars have such good paint (with a 5-year warranty being standard) that most owners would never know if the electronic system was a benefit or not. SLA battery charging with a bench-top supply How do I recharge an SLA battery with just a standard bench-top power supply? I ask because I inherited a nice 24V SLA but my SLA charger does not have a 24V range. I believe it can be recharged with a standard variable power supply via a limiting resistor but what voltage should I set it to and what value of resistor should I choose? Is there a formula for this? Also, seeing the power supply has current limiting, can this be utilised? The rating of the battery is a nominal 24V at about 3.6A. The 12V SLAs I recharge are rated at 2.2A and it would be handy to recharge these from the power supply as well. (B. A., via email). • Typically, an SLA battery can be charged at up to 25% of its Ah capacity. So, for example, a 10Ah battery can be charged at 2.5A. You can charge the battery via a power supply and limiting resistor. Set the supply to 14.4V for a 12V battery and 28.8V for a 24V battery, or use the manufacturers’ charging end-point voltage that is usually shown on the side of the battery. The resistor is there to limit the charging current, typically to the maximum the battery can accept. Assuming the battery is at 23V and the supply is Running An Ultra-LD Amplifier From Higher Voltages I have recently acquired a Pro Series 3 Amplifier with a Pro Series 4 Preamp. I already had a Pro Series Amplifier which I have used for many years. In one of them, I was quite keen to replace the stock Mosfet power amplifiers with the new Ultra-LD Mk.3 boards, as this might offer some noticeable improvements. The obvious problem is that the Pro Series power supply is 70-0-70V which is a tad more than 57-0-57V. I really do not want to purchase new transformers. Will the amplifiers work on the higher voltage or will it kill them? (J. S., via email). • You can’t run the Ultra-LD Mk.3 amplifier module as published from ±70V because its supply bypass capacitors are only rated at 63V. Also, the collector-emitter voltage rating of Q3 and Q4 (BC546) is 65V. 90  Silicon Chip In theory, you could upgrade some components and it would operate from a ±70V supply but it would only be suitable for driving load impedances of 8Ω or above. We published the load lines on page 34 of the July 2011 issue (Fig.6) and this shows how close the 4Ω load line is to the 1-second SOA of the output transistors with the recommended ±57V (nominal) supply. With ±70V and a 4Ω load you would be at serious risk of second breakdown in the output transistors if you drove the amplifier hard. If you really do want to try modifying it to run at a higher supply voltage, you would need to change the following components: (1) 2 x 1000µF 63V capacitor rating must be increased to 80V or 100V; (2) the 470µF 63V capacitor rating must be increased to 80V or 100V; (3) the four 100nF supply rail bypass capacitors (two for each rail) need to be rated at 100V; (4) the 47µF 35V capacitor which connects to the junction of the two 6.2kΩ resistors (at the collector of Q7) needs to be rated at 50V or 63V; (5) Q3 and Q4 would need to be changed to a high-voltage type such as MPSA42. Note that these have the opposite pin-out to BC546s so you would need to install them the other way around. We advise caution if you decide to proceed as we haven’t tested the amplifier module at such a high voltage. While we think the above changes should be sufficient to prevent immediate failure, the increased dissipation in the output transistors could be an issue. Having said that, if you aren’t going to be driving it particularly hard, it may be OK. siliconchip.com.au at 28.8V (24V battery), then the resistor value should be (28.8V - 23V) ÷ (the maximum current). Of course, this also assumes that the supply can deliver the necessary current. The power dissipated in the resistor is the maximum current squared times the resistance (ie, I2R). You must use a resistor with a higher power rating than the wattage calculated. The battery will be charged when it reaches 28.8V. For example, for a 10Ah battery, the resistor value would be (28.8V - 23V) ÷ 2.5 = 2.32Ω, which means you could use two 1.2Ω 10W resistors in series. Battery voltage does not indicate state of charge I have an issue that neither I nor my auto-electrician can explain. I have been having car battery charging issues due, as it turned out, to a faulty alternator which could not achieve the correct voltage output under load. The car in question is a 2000 Ford laser GLXi 1.8L (116,000km) which uses both the ECU and an internal alternator regulator to control alternator output. Recently, the alternator was reconditioned and a new battery fitted. From a voltage standpoint all now looks good: static battery voltage of 12.7V; maximum charging voltage of 14.2V and a floating charge rate of around 13.8V. The charging voltages are maintained under load. However with a fully charged battery, engine running, an alternator/ battery voltage of 14.2V and the headlamps on, a Hall Effect ammeter shows a discharge of around 5A which to me is seemingly impossible with a voltage of 14.2V. The auto-electrician’s clamp meter confirmed the reading to be correct. Increasing engine speed did not materially affect the reading. The alternator is rated at 80A and can provide this level of current if connected to a discharged battery. What could explain this apparent anomaly? Could it be that the ECU, which follows engine temperature/loading/ fuel economy etc, is sensing that the battery is fully charged and therefore “allows” the battery to provide some of the current requirement rather than increasing the alternator output until such time that the state of charge is reduced? In support of this latter supposition the engine was stopped and a major siliconchip.com.au SoftStarter No Good For A Hair Dryer The Power-Tool SoftStarter in the July 2012 issue interests me. I use a 2.3kW petrol-driven generator to operate my power tools. When I turn on my 1500W hair dryer, the poor generator staggers a bit before managing the load. So the Soft Starter should make life easier for the generator. Is this so? (S. S., via email). • We wouldn’t expect the Soft Starter for Power Tools to help much in this situation. The problem you have is not due to a high inrush current. Hair dryers/hot-air blowers are more or less resistive loads and draw an essentially constant current. We measured our lab 1500W hot-air blower at 41Ω when cold which equates to about 230 x 230 ÷ 41 = 1290W. The generator staggering is due to the fact that it has to open its throttle in response to the sudden increase in load but it can only sense this by a drop in the output voltage and/or RPM. It then takes a little time for the motor to increase its power output in response and a little while longer before a new equilibrium is reached. If you can slowly ramp the load up, then the generator will have longer to respond and so may not load (the CCA test) was applied for around 20 seconds and the engine restarted. Now with the headlights on, a significant charge was going into the battery. I would just like to understand what is happening! (M. F., Mount Eliza, Vic). • There can be several processes going on. First, you need to note that the clamp meter does not provide a full picture of what is happening. The clamp meter will be reading the net current flow rather than the separate charge current into the battery and the separate discharge current into the headlamps. So the discharge current flows in one direction and the charging current in the other direction subtract to produce an overall difference current. It is this difference current that the meter reads. You may find that there could be a complete balance where charge current equals discharge current and so the ammeter will read 0A even though there is current flow. At other times, the discharge might be less than the stagger as much. While the Soft Starter does this, its effect is probably too small; it’s designed to suppress very short, very high current transients. For a start, the two NTC thermistors have a series resistance of around 20Ω when cold compared to the hair drier at around 40Ω, so it will only reduce the initial current by about one third. They will also heat up pretty rapidly, over a fraction of a second, and allow virtually the full current to flow. You’re probably better off using a simple AC motor speed controller and simply starting the hair drier at minimum power and then ramping it up over a couple of seconds to full power. Our 230VAC 10A Full-Wave Motor Speed Controller from the May 2009 issue should do the job. However, note that if the hair drier has a half-power setting, this probably won’t work when used in conjunction with the Motor Speed Controller. You will have to use the Speed Controller to adjust the power instead. Note also that you shouldn’t run the hair dryer at a low setting for very long as the air flow may not be sufficient and it could overheat and melt its housing. charge current for a positive current reading. When the discharge is greater than the charge, the current reading will be negative. Nor is battery voltage an indicator of battery charge state. A reading of 14.2V does not necessarily mean that the battery is fully charged. The ECU just maintains the 14.2V so that the battery will not overcharge. Typically, a battery will only be 90% charged when it first reaches 14.2V and it will continue to charge at that voltage, with the current tapering off as it fully charges. Similarly, a 13.8V voltage reading does not mean the battery will accept any more charge since this float voltage is sufficient to maintain full charge. The battery charge current is dependent on the state of charge of the battery. It will not accept charge current when fully charged, regardless of the terminal voltage. If the alternator can deliver the load current then the battery will remain charged. If the battery is fully charged and a load placed on it, the alternator may not initially February 2013  91 Christmas Light Controller Keeps LEDs Partially On I recently decided to build the Christmas light project (SILICON CHIP, October, November & December 2010) and have purchased a number of these lighting controller kits. When I connect all the components together I get an unexpected result. When I turn the system on, the LED strings turn on dimly and remain on for the entire duration of the “show”. Everything works perfectly in the system other than the lights will not turn off completely. I have played around with some of the settings in the configuration file on the SD card and have seen the results change. If I do not enter the Slave = DC line for the controller, the lights still remain on for the duration of the show but do not switch correctly as they do with this line of code. provide charge to the battery. With little loading on the battery, the ECU may have the battery set to float at the lower voltage. A change in load current may then result in the ECU allowing the battery voltage to rise up to 14.2V but with no added charge current flowing. So the clamp meter reading will fluctuate depending on the load and the battery state. NTC thermistor heat question In your SoftStarter project, April 2012, you said the NTC thermistor could not be left permanently incircuit as it would run hot, thus you had the delayed relay to bypass it. However, in the Induction Motor Speed Controller, in the same issue, the same NTC is left permanently incircuit. Isn’t this a contradiction? (D. H., via email). • We don’t want the hot NTC thermistor in a tiny plastic enclosure which might melt. That’s not a problem in the much larger case of the induction motor controller which already has a large heatsink inside it. Courtesy light inhibits central locking I have an interior dome light kit which works a charm, but I can not activate my central locking until the 92  Silicon Chip I have similar results with the Triac = delayed / immediate line. I run the configuration file with the suggested settings as per the kit instructions. If I turn the system on without an SD card or without any data on the SD card, the slave kit does not allow anything to turn on at all and even the dimly lit issue does not occur. As soon as the lights turn on for the first time they then remain on for the duration of the system being powered up. Switching between slave kits yields the same result. As such, I suspect either the configuration file or the master kit. Any suggestions to help me resolve this would be greatly appreciated. (G. H., via email). • This sounds like it is due to the “filament preheat” feature, intended lights go off. Is there a way to modify the circuit or get a different power feed to fool the system into thinking the lights are off when they are not and so forth? I want it so that central locking can be utilised straight after the door is closed.(M. J., via email). • We are not sure what the central locking is detecting with the interior lights on. It is probably the current through the interior lamps. You may have to experiment with the interior lights wiring to find out which wiring method solves this. Perhaps a separate 12V supply from the battery via a fuse would solve it instead of the original interior lighting wiring via the original fusebox. L’il Pulser train controller Many moons ago you published an article on building a L’il Pulser Model Train Controller (SILICON CHIP, February 2001) and subsequently Dick Smith sold a kitset. I recently got around to building it and this is my very first attempt at building anything electronic. All went very well until I discovered the relay supplied in the kit did not fit the PCB but I got around that by getting a replacement from Jaycar. I finished the job and ran the test routine using an unregulated 12V DC supply off my Hornby train controller. to prolong the life of incandescent lamps that may be connected to the unit. This feature is not automatically turned off when you use a slave in DC mode, so you need to turn it off separately. If filament preheat is left on for a DC slave, it effectively sets a minimum duty cycle and so the LEDs will remain dimly lit at all times (except for when they’re driven more brightly). There are two ways to turn it off. You can either turn it off for all slaves with a line like this in the configuration file: filament preheat amount = 0 or you can turn it off on a per-slave basis with a line like this: filament preheat 1 = no filament preheat 2 = no etc. In forward mode, the track voltage LED remained a constant green when it should have grown brighter with changes in the speed pot. I adjusted VR3 correctly to 2.0V. The piezo works but not when I short the outputs. If I place a loco on the track it is no go. The speed LED is a constant weak green at zero but starts flashing green when VR1 is wound up – still rather weakly. VR2 was adjusted without the loco and set to mid-point. I checked the output at full speed and the best I can get is 5.7V. I cannot see any errors. The only one thing that slightly bothers me is diode D3. It’s very tiny but I am pretty sure it’s installed correctly with the cathode (black ring) to the left as I look at the circuit. (D. J., via email). • Using a multimeter set to DC volts, check the output of IC2a at pin 7. This should vary from approximately 3V to 9V as VR1 is adjusted. This voltage range is dependent on VR2’s setting. If this is not correct, check the placement of all components. The D3 orientation you mention is correct. Make sure all components are soldered in place and that the wire links (shown as a line on the overlay) are installed. Also check if there is low resistance between the 17V supply and one side of the motor output terminal, then check for low resistance between the other side of the motor terminal and the drain of Q1. This checks the relay siliconchip.com.au contacts and you should get a reading of below 1Ω. With reverse, the low resistance between the 17V rail and Q1’s drain should be on the opposite terminals. Upgrading the solar charge controller I built the MPPT Solar Charger Controller from the February 2011 issue and it works great. However, I’ve upgraded my hardware and I need to figure out the design modifications required to amp it up. I now have a 175W panel and a 200W panel. I’m also charging two N120 batteries, ie, two 120Ah 12V in series for a 24V configuration. The inductor seems to be overheating (not surprising) and reaches over 95°C. I suspect this means also that the inductor is saturating. The problem is the unit does not produce 28.8V across the batteries, even when the batteries have been fully recharged prior to switching the module into circuit. I’m wondering if my unit is actually faulty? Essentially, as far as I can read the schematic, I may need to duplicate the power line of the design, duplicating diodes, Mosfet, capacitors and inductors. However, after much contemplation, I suspect a modified design for the inductor will likely suffice. Even running as it does, the unit switches into float mode after reaching a terminal voltage of 25.5V. The indication is that something may be faulty. I adjusted the voltage feedback to trick the system into running the bulk phase longer and so far this has not been a problem. The set-up I have is quite interesting in its own right and forms the cornerstone of an eco-living project. The batteries are driving a 3kVA inverter that easily runs a 25% duty cycle Hum Problem In Preamp And Amplifier I recently built a Studio Series Preamplifier together with the 20W Class-A Amplifier. The amplifier is excellent but when I connect the preamplifer, it makes an annoying humming sound. I have tried to follow the instructions about earthing but it has not gone as planned. I have probably missed or misunderstood something. Also, I have replaced the main switching board inside the unit but the hum is still there. I have tried to connect the preamp to the amplifier with an earth wire as well. Although the hum has reduced, it has not gone away completely. Can you tell me what I am doing wrong? It appears like it’s an earthing problem – maybe an earthing connection within the case which I missed out. (C.T., via email). • There are several reasons why hum can be introduced into audio signals. If each piece of equipment is OK separately but there is hum when you combine them then that suggests an earth loop is the cause. switchmode arc welder! So I can weld in the bush and use a drop saw and other power tools for mobile repairs. I run a home-maintenance business and even in the city when I’ve fronted and a customer wasn’t home and no external power points were available, my rig got the job done without resorting to a generator. I’ve also tried running a fan directly on the circuit board with cover removed, after I found that bolting a heatsink to the case didn’t perform well enough. Unfortunately, the case lid holes don’t nicely line up with an off-the-shelf DC motor, which could be run by the PIC if you wanted to get There is a paragraph towards the end of the construction article (page 72, July 2006) which says: “. . . if you notice more hum in your audio system after connecting the preamp, then try disconnecting the earth wire to the preamp module. Never, ever disconnect the mains earth from the chassis!” That is what you will have to do. You can just de-solder (or cut) the earth wire from the input board at the rear of the preamp. Don’t change the other earth wires, ie, those going to the pot body and chassis. It is normal to have the power amplifier earthed and the other equipment floating, to avoid this very problem. If that still doesn’t fix it, the problem is likely either a power supply rejection problem in the preamp (which may be due to a faulty component) or else hum coupling into the signal path due to mains cables being run too close to signal cables or signal-carrying PCBs. fancy. But even running continuously would probably help in my intended scenario. I was wondering if the internal resistance of the batteries (as they are real whoppers) is significantly lower than, say, a 40Ah battery designed to deliver 400 CCAs. These puppies will spit out something like 860 CCAs. Any additional information you can provide for this kit would be welcome. I am an electronics engineer, although a little rusty as I’m not working in this field on a regular basis. (P. H., via email). • As far as the inductor is concerned, you could try to increase the current continued on page 96 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 Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable. siliconchip.com.au February 2013  93 STIC FANTAIDEA GIFT UDENTS FOR SFT ALL O S! AGE THEAMATEUR SCIENTIST An incredible CD with over 1000 classic projects from the pages of Scientific American, covering every field of science... THE LATEST VERSION 4 – WITH EVEN MORE FEATURES! Arguably THE most IMPORTANT collection of scientific projects ever put together! This is version 4, Super Science Fair Edition from the pages of Scientific American. As well as specific project material, the CD contains hints and tips by experienced amateur scientists, details on building science apparatus, a large database of chemicals and so much more. ONLY 62 $ 00 PLUS $10 Pack and Post within Australia NZ P&P: $AU12.00, Elsewhere: $AU18.00 “A must for every science student, science teacher, science lab . . . or simply for those with an enquiring mind . . .” Just a tiny selection of the incredible range of projects:  Build a seismograph to study earthquakes  Make soap bubbles that last for months  Monitor the health of local streams  Preserve biological specimens  Build a carbon dioxide laser  Grow bacteria cultures safely at home  Build a ripple tank to study wave phenomena  Discover how plants grow in low gravity  Do strange experiments with sound  Use a hot wire to study the crystal structure of steel  Extract and purify DNA in your kitchen Create a laser hologram  Study variable stars like a pro  Investigate vortexes in water  Cultivate slime moulds  Study the flight efficiency of soaring birds  How to make an Electret  Construct fluid lenses  Raise butterflies as experimental animals  Study the physics of spinning tops  Build an apparatus for studying chaotic systems  Detect metals in air, liquids, or solids  Photograph an ant's brain and nervous system  Use magnets to make fluids into solids  Measure the metabolism of an insect . . .  and many, many more (a thousand more, in fact!) See the V2 review in SILICON CHIP, October 2004. . . or read on line at siliconchip.com.au This is the ALL-NEW Version 4 . . . it’s even BETTER! HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-5 Mon-Fri BY FAX:# <at> (02) 9939 2648 24 Hours 7 Days BY EMAIL:# silicon<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# BY PAYPAL:# PO Box 139, Collaroy NSW 2097 silicon<at>siliconchip.com.au 24 Hours 7 Days * Please have your credit card handy! # Don’t forget to include your name, address, phone no and credit card details. BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information There’s also a handy order form inside this issue. Exclusive in SILICON Australia to: CHIP siliconchip.com.au 94  Silicon Chip siliconchip.com.au MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP C O N T R O L S Tough times demand innovative solutions! Vast range of SEMICONDUCTORS We stock the broadest range of Semiconductors as used in Consumer Electronic Equipment. As well as all the common types, we have in stock many hard to find and obscure Semis. Competitive prices. ELNEC IC PROGRAMMERS 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 Made in Australia, used by OEMs world-wide splat-sc.com IMAGECRAFT C COMPILERS FOR SALE SOLAR PANELS LOW COST: full range 5W to 250W, eg: 40W/12V Poly $69, 130W/12V $169, 190W/24V $165, 200W/12V $225, 250W/24V $225, 230W Poly $190. AGM Batteries: 7AH $19.50, 9AH $24.50, 20AH $52.50, 55AH $129, 105AH $199, 220AH $399. (03) 94705851 or (03) 9478 0080 chris<at>lowenergydevelopments.com.au www.lowenergydevelopments.com.au 544 High St, Preston 3072, Melbourne. questronix.com.au – audiovisual experts solve home, corporate security and devotional installation & editing woes. QuestAV CYP, Kramer TVone (02) 4343 1970 or sales<at>questronix. com.au PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 8068 2713. sesame<at>sesame.com.au www.sesame.com.au LEDs! Nichia, Cree and other brand name LEDs at excellent prices. LED drivers, including ultra-reliable linear driver options. Many other interesting and hard-to-find electronic items! www.ledsales.com.au PCBs & Micros: Silicon Chip Pub­ lications can supply PCBs and prosiliconchip.com.au Visit us at www.starcomponents.com.au ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 GRANTRONICS PTY LTD www.grantronics.com.au ATTEN SOLDER STATIONS grammed micros for all recent (and some not so recent) projects described in the magazine. See the SILICON CHIP PartShop advert in this issue. Phone (02) 9939 3295 or email silicon<at> siliconchip.com.au WANTED CIRCUIT & DESIGN IDEAS: SILICON CHIP pays up to $60 for Circut Notebook items or you could win a $150 gift voucher from Hare & Forbes. CUSTOMERS WANTED: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects 50W AT937B . . . $35:00 60W AT938D . . . $65:00 Television Replacements 134A Ayr St, Doncaster 3108 Phone (03) 9850 4144 sales<at>tvr.com.au including Drew Diamond. 27 The Mall, South Croydon, Melbourne. Phone (03) 9723 3860. www.electronicworld. com.au KIT ASSEMBLY & REPAIR KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com ADVERTISING IN MARKET CENTRE Classified Ad Rates: $29.50 for up to 20 words plus 85 cents for each additional word. Display ads in Market Centre start at $110.00. All prices include GST. Closing date: 5 weeks prior to month of sale. To book, email the text to silicon<at> siliconchip.com.au and include your name, address & credit card details, or phone Glyn (02) 9939 3295 or 0431 792 293. February 2013  95 Advertising Index Altronics.................................. 66-69 Amateur Scientist CD................... 94 Blamey & Saunders Hearing.......... 5 HB Wireless Sales & Service..... IBC Embedded Logic Solutions............ 6 Emona Instruments...................... 57 Front Panel Express..................... 11 Futurlec........................................ 10 Grantronics................................... 95 Harbuch Electronics..................... 59 Hare & Forbes.......................... OBC Ask SILICON CHIP . . . continued from p93 rating by stacking two cores together and winding 0.7 the number of turns originally specified around both cores. The changes for a 24V battery are detailed in the original article in a separate panel. These include changes to the inductor windings. Note that diodes D1 & D2 are only rated for a 100W solar panel, not for 175W. Make sure that any higher-rated replacement diodes are also Schottky types so that the circuit can operate at 32kHz. The low-ESR capacitors need to be increased in number to cope with the extra current. The PCB tracks and fuse are also not suited for the extra power involved and will need to be upgraded. The PCB tracks for the charging section could be beefed up with tinned copper wire. High-energy ignition for old twin-cylinder I have a 2-cylinder Kohler engine driving a wood chipper. Originally it had a “double-ended” ignition coil activated by a conventional set of points from a 12V battery. The coil was damaged beyond repair and a replacement was both expensive and hard to get so I ended up using two conventional 12V coils and condensers wired to the points to get the job we were doing finished. This was some months ago and the decision has been made that the machine should be fixed properly. I thought about using one of your transistor ignition designs but didn’t know if it would handle the two coils. I then went to see my friendly auto-electrician and spoke to him about using a 96  Silicon Chip DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au Notes & Errata High-Energy Electronic Ignition System, Nov-Dec 2012: readers building the coil tester version of the High Energy Electronic Ignition System, as depicted in Fig.10 on page 50 of the December 2012 issue, should be aware that there is a risk of failure in the LM2940CT-5 regulator and the PIC microcontroller due to high voltage spikes superimposed on the common positive lead from the battery to the coil and the ignition module. To avoid this risk, the coil tester should be built exactly as we have configured it for the Jacob’s Ladder in this issue, including the added protection components for the regulator: 10Ω resistor, 13.6V TVS and 1000µF 25V DC input capacitor. These additional components are not required for the other versions of the High Energy Electronic Ignition System. Commodore ignition coil (which he gave me) but he says that they need a special driver. Jaycar has a number of electronic ignition kits but the people in the Port Macquarie shop were unsure as to what would be needed. (D. H., via email). • If you only have one set of points Instant PCBs................................ 95 Jaycar .............................. IFC,45-52 Keith Rippon................................. 95 Kitstop.......................................... 10 LED Sales.................................... 95 Linkwell........................................ 11 Low Energy Developments.......... 95 Microchip Technology..................... 3 Mikroelektronika............................. 7 Ocean Controls............................ 37 Quest Electronics......................... 95 Radio, TV & Hobbies DVD............ 87 RF Modules.................................. 96 Sesame Electronics..................... 95 Silicon Chip Binders..................... 70 Silicon Chip Bookshop................. 79 Silicon Chip Order Form............... 89 Silicon Chip Partshop................... 88 Silicon Chip Subscriptions........... 21 Splat Controls............................... 95 Star Components......................... 95 Television Replacements............. 95 Tenrod Pty Ltd.............................. 19 Truscotts Electronic World............ 95 Wiltronics..................................... 8,9 Worldwide Elect. Components..... 96 driving a coil with two HT output terminals then a Commodore coil driven by our High-Energy Ignition System (SILICON CHIP, November & December 2012) is the way to go. In fact, if you read the Jacob’s Ladder article in this issue, you will see that we are using a version of our High-Energy Ignition. For your application, build the points version of the kit. Altronics or Jaycar SC can supply the kit. siliconchip.com.au Through wind and rain, through flood and dust, through snow and sleet . . . NOTHING is going to stop this little beauty Looking for the ultimate in commercial UHF transceivers? Check out the specs on the new XR-M Series from HB Wireless. Or better still, check out one of these for your application – call HB Wireless or visit the website – www.hbwireless.com.au – for more information. CERTIFIED IP68 2 YEARS “Hot Sw Replac ap” ement Warra nty! so it’s waterproof – and dustproof!                 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SHOWN HERE LIFE SIZE: Just 52 x 103 x 32mm; weight 250g (with battery) siliconchip.com.au HB WIRELESS 202 Whitford Rd, Green Valley, NSW 2168 Phone (02) 8763 7651 Fax (02) 8076 8686 Email: sales<at>hbwireless.com.au Website: www.hbwireless.com.au February 2013  97 Corporate Bronze Member 24324