Silicon Chip 2005 №10

["tj. tll \u00a1 \\\\\\\\ F \\\\Yt Jlr T \u00a1TTT{ rlirl: rl \\\"tfi $E\u00a1 sl03 BUITDII{G VALVE AMPt\u00a1FIERS EMC FOR PRODUCT DESIGIIERS -By Morgan Jones Published 2004 By Tim Williams. A hands-on guide to valve electronics - classic and modern. First published 1992. 3rd edition 2001 . Suitable for beginners and more experienced amplifier Widely regarded as the standard text on EMC, provldes all the key information designers. Covers building, modifying, fault-finding and repairing valve needed to meet the requirements of the EMC Directive. Most impofiantly, it shows how to incorporate EMC principles into the product deslgn process, *\\\"st0ampliflers. Numerous illustrations. 354 pages in paperback. avoiding cost and performance penalties, meeting the needs of specific stand- ards and resulting in a better overall product. 360 pages in paperback' conventional telephone f undamentals, including analog and digital c0mmu- starting with a brief review of fundamentals relevant to valve amplifiers; nication techniques. Provides basic information on the functions of each tele- simple stages, compound stages and finally complete designs. lt will walk you through all siages of design so that you can create your own wonders 6lT phone component, how dial tones are generated and how digital transmission techniques work, 402 pages, soft cover. s8t pages in paperback. $83 VIDEO SCRAMBTIiIG & DESCRAMBTIl{G GUIDE TO TV & VIDEO TECHiIOT(IGY -By Eugene Trundle 3rd Edition 2001 FOR SATELLITE & CABTE TV by Graf & Sheets -2nd Edition Eugene Trundle has written for many years in Television Ever wondered how they scramble video on cable and satellite TV? This book magazine and his latest book is right up to date on TV and video technology' lncludes both theory and practical servicing informationand is ideal for both tells you! Encoding\/decoding systems (analog and digital systems), encryption' even schematics and details of several encoder and decoder circuits for experi- students and technicians. 382 pages, in paperback. mentation. For both the hobbyist and the professional. 290 pages in paperback. AT{AIOG TECHI{IQUES WITH DIGITAT IilTERFAGI]IG engineering, experimental science course, MSc electronics s48 and electronics units for HNDs. Text is supported by numerous worked examples and experimental exercises. 312 paoes in paperback. iliftH*iili'\u00fc\u00f9if'Jil.fi#i\u00e4i*ififiifii:it;i\u00eer[ffi,*rrfr'il\u00e4k\\\",\u00ee,\u00ee'\u00e5:,rhiffl':ilt '',I,',\u00efr'il.\u00ee* f cDRmnreun sctENTtsT ............. ......... .. $4e.00 TAX INVOICE f nrunloo ctRcutrTEcHNlQUES wDlclrAL 1Nr............ . ....$69.00 I ELEcTRoNtcsnrunloe .....$8e.oo ff ELEcTRoNtcsnuoro ........$92.00 Your Name f DESIGNnuoro powER AMPLIFIER . .......... $89.00 f autotrrrc vALVE AMPLTFIERS ........ ... .............. .............. ...$69.00 Address f HATcouelrre REFERENcE RED f DBtvESovo eLAvERS AND ...............$89 00 t ....lecrnlc MoToRS AND DRIvES .... ........... .......$79.00 Postcode ff DESTGNERSrvc FoR pRoDUcr ...........$63.00 ........,.....$103.00 (-)Daytime Phone No. \u00cd e uror To rv & vtDEo TEcHN0LoGY .......... ................. ......$63.00 sT0 f ..rrurrnrnctruG wtTH c....... ........................$63.00 Email \u00cd w'corurnoLLER PRoJEoTS lN c F0R 8051...........,........... ,.$73.00 B op nups FoR EVERYoNE Payment details: I pRAcTtcEerc rN ............,...... ...$52.00 t Cheque\/Money 0rder enclosed f etc - youR pERSoNAL tNTB0DUCToRY couRSE ..............$46.00 -Charge my credit card OR fl c00K800K.......pow\u00a1n supplY ...,............$9e.00 f HANDB00KenRcrrcnl RF n fVisa Card MasterCard .........................$69.00 i pnncr. vARIABLE sPEED DRtvES\/PowER ELEcI... .. ........$85.00 t srnvtcrruc TV SATELLtTE & vlDEo EQU1PMrNT............... ..$70 00 il rH\u00a1 wTRELESS NETWoRKING STARTER KlT............ ... ......$48.00 date t uruornsrnNDtNG TELEPH0NE E1EcrR0N1cs........................$70.00 Sig natu re ORDER TOTAL$ AU \u00cd AMeLIFIERS......vnrvr ........$105.00 B00K TOTAL: S.,..,. t vroeo ScRAMBLING\/DEScRAMBLING ...... $87.00 ALL TITLES SUBJECT TO AVAILABILITY, PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY ALL PRICES INCLUDE GST","The Harbros 12154B- transceiver Designed specifically for rural fire brigade FS6 and many other ex-service sets networks in the early 1-950s, the Harbros 1,2154B did require changes, as their transmit- transceiver was a 1.Z-valve unit with some interesting design features. It superseded army- ting frequencies were controlled only surplus transceivers that had been adapted for the job and was much easier to operate. by a VFO. The Postmaster Generals By the end of World War 2, the prices. As a result, transceivers such Department required the transmitters value of radio communications was as the FS6 and the 122 (described in apparent and returned servicemen May 2003 and October 2003 respec- to be crystal-controlled, which meant fiom country areas quickly realised tively) were quickly pressed into they had to be modified and submitted that2-wayradiocouldhelpcoordinate service on rural fire-brigade services. for approval. fire-fightingactivities.Notonlywould In addition, many of these sets were activities more effective Disadvantages it make such ensure greater safety for busyefdisbhyintghefleFelyisin. g\\\" Doctor Service and 6ut it would Although army-surplus transceivers flrefighters as well. The 1.22 required no modif\u00edcations worked well in these roles, they did \u00c2t that time, here were many thou- to make it suitable for use in these have their disadvantages. Generally, sands of high-fiequency (HF) portable services, as it had both a variable-fre- transceivers available on the military quency oscillator (VFO) and a crystal- they were quite bulky and heavy, were surplus market at very moderate controlled transmitter. However, the often difficult to service and could often only be operated effectively by someone with technical knowledge. They also usually had limited power outputs while at the same time draw- ing high currents when operated from a vehicle battery. That list of negatives didn't prevent the sets from being used for fire-bri- gade or fishing fleet communications though, When you have nothing else to use, you will work around any problems you encounter - which the various operators and networks did with considerable success. More suit- able commercial transceivers were rare and costly at that time. As the supply of cheap army- surplus equipment gradually dried up, manufacturers began releasing commercial HF transceivers to meet the increasing demand for equipment, Naturally, this new equipment was manufactured to meet specific requirements, rather than being adaptations of military equipment, For example, some malufac- turers concentrated on produc- ing marine equipment, while others concentrated on land-based applications. One such company, Hardinge Brothers of Horsham, Vic- toria,. specialised in HF transceivers for the rural fire-brigade networks 100 StucoN Cutp siliconchip.com.au","An under-chassis view ofthe circu\u00edt is to the right. - mainly the Country Fire Authority compared to the ex-service equipment, Next comes a 455kHz IF amplifier as the more critical transmitter tuning based on a 68A6 (V3) and this is then networks in Victoria. followed by a 6NB (Va) as the second controls are preset within the case. detector, AGC diode and first audio The Harbros L2l54B In fact, there are only five controls amplifier. The audio from the detec- tor then goes to a noise limiter which Hardinge Brothers produced do- in all: (1) receiver audio level; (2) mestic radios before the war, although uses a 6AL5 (V6) dua\u00cc diode. This apparently only in limited quantities. receiver tuning (z-alttlHz); (3) trans- stage limits impulse interference, af- The company subsequently tooled up mitter frequency selector; (4) receiver ter which the audio is fed to the 6NB for the production of HF transceivers variable tune or crystal-locked tuning in the early 1950s and the first unit selection; and (5)noise limiter on\/off. pentode section. produced (as far as I am aware) was the The power on\/off switch has three A 6AQ5 (V5) functions as the second 11153M- an 11-valve, single channel, positions: [r) 12 VDC; (Z) off; and (3) HF transceiver with an output power audio amplifier which in turn drives of sW. The \\\"11\\\" in the mode\u00cc number 24OVAC mains. refers to the number of valves used, the loudspeaker. \\\"53\\\" to the year of initial production Tt'e 121548 transceiver was expect- Transmitter circuit and the \\\"M\\\" to the fact that it was ed to operate on AC po-vver most of the The transmitter section uses six primarily a mobile transceiver. time, with 12V DC operation included valves in all (V7-V12). APierce crystal The later L2154B model is a 12-valve as a back-up in case the base station oscillator based on a 6AQ5 (V11) and location lost mains power. three switch-selectable crystals sets unit (not including power supp\u00ccy the canier frequency, although only Receiver circuit two crystals were usually fitted to the rectifiers), first manufactured in 1954. unit. For example, in the unit I have, The receiver circuit (see Fig.1) is the crystal fiequencies a\u00a1e 2692kHz It was primarily intended as a base similar to that used in many high-per- and +s10kHz.The third position was left vacant, as licences were usually tra\u00a1rsceiver and is rather more versatile forma\u00a1ce domestic receivers of the era. only issued for two lrequencies. A 6BA6 (V1) acts as a tuned RF stage than the 11l53M, as it could transmit and this is followed by a 6AEB (V2) The output of the crystal oscillator as a fiequency converter. Although a is applied to the grid of the RF (radio on three crystal-locked channels. The conventional oscillator circuit is used frequency) power amplifier, which is receiver could tune continuously from based on a 6L6G (V10). V10's output 2-6MIHz and also boasted two crystal- for the variable tuning, two frequency- locked channels. controliing quartz crystals in a Pierce OcroBER 2005 101 The controls on this set are some- oscillator circuit are used for fixed- what simp\u00ccer to understand and use frequency reception, siliconchip.com.au","-r!ts1 \u00a1 \u00e4\u00cbe\u00cb is then coupled via a tuned circuit to \u00ef \u00cbt\u00e5\u00cb the antenna. This stage is tuned to suit JiL-+ the crystal frequencyby switching dif- \u00e3$+\u20acF ferent values of capacitance in parallel \\\"\\\\t with the output coil. ES 3.e\u00a1 ro2 StucoN Cntp In operation, the \\\"Ioading\\\" of the .\u00cb e \u00cb E\u00cb transmitter is adjusted to give op- timum output. This is achieved by eiif \u20ac FE\u00e5 varying the position of a coupling coil which is wound onto a former and '.\u00e8\u00cb:0i]\u20ac\u00c8,\u00c9?='P\u00f5so\u00a1.3s= placed over the main tuned circuit winding - see photo, The modulator is a 3-stage device based on valves V7-V9, V7 (a 6AU6J is wired as a grounded-grid audio amplifier, with a carbon microphone in the cathode circuit. Its output is fed to another 6AU6 (VB) connected as a triode and this in turn feeds a 6L6G [V9) modulator output valve, The resulting audio signal fiom V9 modulates the RF signal via a centre- tapped audio choke. As shown, this is wired into the plate circuit of VO and into the plate and screen circuits of the RF output stage (V10), V12 [6U5\/6G5) functioned as a magic-eye tuning indicator (to indicate modulationJ. PTT switch The changeover foom receive to send is accomplished by pressing the PTT (press-to-talk) button on the unit's Zephyr carbon microphone. This actuates a 3-pole relay and one set of contacts transfers the HT (high-ten- sion) voltage from the receiver to the transmitter. At t\u00ece same time, a second set of contacts swaps the antenna fiom the receiver to the tralsmitter, while the third set removes a short circuit from the HT at V7 in the modulator and shorts the loudspeaker voice-coil to earth. The last operation is necessary to prevent acoustic howl fiom occurring at the changeover from transmit to receive and vice-versa. It occurs be- cause the transmitter and the receiver remain in operation for a fraction of a second after a changeover, as the filter capacitors in the supply rails lake a finite time to discharge after the HT is removed, Mechanical clean-up The transceiver featured here had been in continuous service from 1961 until the early 1970s, when the Coun- try Fire Authority changed to VHF ra- dio communications, It then ended up in a garage at a coastal location, where siliconchip.com.au","the salt-\u00ccaden air rusted the cabinets. The maior components laid out on the top of the chassis, Power When I used an angle-grinder to clean comes from an\u00e8xternal rator supply. the rust off the lid, I found that it had penetrated some distance underneath lems. A quick inspection revealed that a resilient-mount socket, so the noise the paint. the 2nF buffer capacitor in the vibrator is quite noticeable when the unit is operating. It probably really doesn't Fortunately, the transceiver and section had been overheating and had matter, as this is a communications power supply cabinets were in much leaked wax onto the bottom cover of transceiver and the receiver is likely better condition. After removing the to be used in an area where interfer- circuitry, they were rubbed down with the power supply. fine sandpaper to remove any loose ence and general background noise is I initially checked the capacitor with paint and rust. The cabinets were then present anyway. my 1000V tester and found it had a The supply was also checked for anY cleaned down with turpentine and given a coat of Wattyl Killrust metal Ieakage resistance of about 30MO. I shorts or low-resistance readings from then decided to heat the capacitor with the high-tension (HT) line to chassis. primer undercoat. a hair drier and observe the change (if There were no problems here, so the any) in its leakage resistance. When I two 6X5GT rectifiers thai had previ- That done, I went looking for a ously been removed were reinstalled. did this, its resistance quick\u00ccy dropped The suppty was then switched on and spray paint that would roughly match the original green. Eventually, I came to just 1.sMQ, so it was replaced im- the voltage across the filter capaci- across a hammer-tone metal finish mediately.' tors carefully monitored. Then, after in fade Green, This closely matches a few seconds, the supply was turned the original hammer-tone finish so I Unfortunately, I didn't have a suit- back off again, this cycle then being bought a can, even though it is rather repeated several times to reform the able high-voltage (2000V) 2nF capaci- expensive. It is labelled as Galmet electrolytic capacitors, tor so I made one up using three B.2nF It really pays to be rather gentle with metal protection and is easy to use. Next, the knobs were removed and 630V polyester capacitors in series 6X5GT rectifiers, as they are prone to develop short circuits from cathode cleaned by scrubbing them with a nail across the secondary of the transform- er. The higher resulting value (about to filament if they are abused to anY brush dipped in soapy water, They 2.7nF) gives a lower standing current extent. When I had flnished overhaul- were then polished with an automo- with no load, so the transformer is bet- ing the transceiver, I took the same pre- tive cut ald polish compound ald now ter tuned than it was with the original 2nF capacitor. The voltage rating of cautions with it, as it is on a separate look much brighter. chassis to the power suPPlY. Next stop was the volume control. the three capacitors in series (about Overhauling the receiver This was extremely stiff to rotate, so 1890V) is slightly lower than the rat- As is my usual procedure, I com- I sprayed Inox cleaner onto the shaft ing of the original capacitor but this is menced overhauling the receiver sec- and rotated it back and forth uniil it unlikely to cause problems. tion by testing the paper capacitors, The circuit shows the vibrator to be And I have to say that the units fitted operated freely. The va\u00ccves were then to this set would have to be the worst a V6612 Oak unit, However, a V6606 cleaned with soapy water, with only is fitted with a 20e) resistor in series batch I have come actoss. gentle rubbing on the glass envelopes with the reed drive to drop the voltage OCTOBER 2OO5 103 to around 6V. The drive voltage was to ensure the labelling remained in 9V so I changed the resistor to 56Q place. and the voltage is now much nearer As a precaution, the octal valves to what it should be. were all held upside down while this work was being done, so that no water The vibrator itse\u00ccf is not mounted in could seep into the valve bases, This isn't necessary with the miniature valves, since the valve pins emerge direcily through the glass envelope. After that, it was a matter of attend- ing to a few sundry details. The front palel was cleaned with a kerosene- soaked rag, after which the dents were removed from the speaker grill. The grill was then resprayed with flat-black paint and came up looking like new. A kerosene-soaked rag was also used to c\u00ccean the top ofthe transceiver chassis. I also replaced the 240V power lead (it was starting to perish), cleaned the microphone and adjusted the PTT switch. Servicing the power supply A combined 24ov AC a\u00a1rd 1 2V vibra- tor power supply is used in these units. and this one wasn't without its prob- siliconchip.com.au","So\u00fcFho\u00fco @a[flenru Kflmgsfloy ffit n continuity across the primary winding and this proved to be intact, First marketed in Australia in 1946, this Kingsley receiver used \\\"ferrotuning\\\" to tune in stations (as opposed to the more conventional variable-capaci- Once these checks had been com- tance tuning). This new system used a grooved brass spindle to actuate sliding iron-dust cores inside the tuning coils, thus varying their inductance. pleted, it was time to apply power, The set came with a colourful dial and circuits for three, four and S-valve I began by reforming the electrolytic models were available.The unit shown here is a 5'valve KFT-1 medium-wave capacitors as described previously, model using 6J8G,6U7G,6GBG,6V6G and 5Y3G valves. Ferrotuning never then let the receiver run. There wasn't gained widespread popularity and such sets are now a rarity. (Restored by Maxwell Johnson; photo by Ross Johnson). so much as a peep out of it - it was They consisted mostly of miniature the only exceptions being the cathode dead quiet. ,\\\\EE units [brown coloured] and their leakage resistances varied between 1- bypasses on several of the valves. In It was time for some troubleshooting 10MC\u00bf (as measured on a high-voltage the end, some 26 capacitors in total and I started by checking the voltages around the 6AQ5 output stage (V5). tester set to the 500Vrange). A couple were replaced in the receiver and This showed that the cathode voltage of these capacitors were also buried under shielded audio cables and un- transmitter circuits. was zero, which meant that no current less you went looking for them, they could have been easily missed. The resistors were mostly 20% was being drawn by the valve. tolerance types and most had gone I had no opiion but t\u00f3 replace the lot, I also measured the heater voltage high by about 20%, so I didn't need to and found that there was 12V across replace any. I also checked the speaker the valve socket instead of 6V. This indicated that the heater had probably transformer to make sure there was gone open circuit. This close-up view shows the power I removed the valve and found that amplifier tank coil, together with the the heater was intact, so I replaced it coupling coil which again. It still wasn't drawing current, has too many turns, so I removed it again, re-tensioned the The roughly-wound 3-turn coil over the socket pins and gave the socket a spray tuned winding gives better performance, with Inox lubricant. This time there 704 SILIC)N CHIP was some action and the receiver came to life, although it was very noisy. I tried wriggling the valve around in its socket and this produced loud crackles. After moving the valve around for a while (to clean the con- tacts), these crackles disappeared - or at least, they did for this stage. There were still problems elsewhere. Next, I tried moving the 6BA6 RF stage (V1) around in its socket and the same crackling problem occurred. Its socket was also then sprayed with cleaner and the pins re-tensioned be- fore replacing the valve. And again, the crackling problem disappeared. The set was now sounding much better, so I attached a signal genera- tor to the receiver's antenna, tuned to one of the crystal-locked channels and adjusted the generator for an audible signal, The sensitivity was poor, so I checked around the 6AEB converter stage (V2J and cleaned the frequency selector switch which was also noisy. This made no difference to the sen- sitivity so the 6AEB was removed and its socket also given the \\\"treatment\\\". This did improve the performance but when I subsequently touched the 6BA6 IF valve [V3], the crackling became quite bad and the sensitivity varied widely. This valve was also removed a\u00a1rd its socket cleaned and tensioned, after which the sensitivity improved quite siliconchip.com.au","noticeably. I then checked the remain- The set now tunes quite well and Having replaced the capacitors, it ing valves and found that their sockets signals well below a microvolt are all had bad contacts. readily heard. It really is quite a \\\"hot\\\" was time to test the transmitter into a dummy load\/p'ower meter. I pressed These were all given a good clean receiver! up and the receiver was now turning the button on the microphone and in a reasonable performance. AII those I didn't touch the IF alignment, as it years spent in a salt-laden atmosphere adjusted the tuning capacitor on each had certainly caused some problems. appears to be perfectly OK. Note that of the transmit frequencies but could Receiver alignment care is needed in tuning the IF of a crystal-locked receiver, as just peak- only get 5W output on 2692kHz and At this stage, I decided that a quick ing the IF alignment may mean that realignment of the receiver's front-end the receiver is no longer tuning the 3W on 4510kHz with 15W input was the way to go, frequency it is intended to tune. - pathetic! First, I set the tuning to the 2692kJfz For example, to tune fo 2692kH2, My suspicion was that the link crystal-locked position and rotated the receiver's tuning dial until an increase the receiver's crystal oscillator must coupling coil to the antenna had too in sensitivitywas observed. That done, operate aI 31.47kII2. That's assuming many turns on it (12). To test this, the signal generator was adjusted until an IF of 455kHz (\u00ede, 31.47 - 2692 = a55). I temporarily converted the output the signal was audible. I then peaked the RF and aerial coils slugs for best However, if the IF was aligned to say circuit to a Pi coupler and the output performance, after which the receiver was switched to 4slokHz and the 465kHz, the actual frequency that the increased to 7W on 2692kllzto BW on signaJ. generator and receiver tuning again adjusted for best performance. receiver would now tune would be 4510kH2. I then experimented with The aerial and RF coil trimmers were 26\u00ef2kIfz (ie, 31.47 - 465 = 2682). the link coupling coil and found that then adjusted, At this stage, there was just one three turns (instead of 12) resulted in Unfortunately, the variable fre- remaining problem with the receivet quency oscillator adjustments did an output of 6W. not line up with the settings for best - the hum level was quite noticeable. This was still rather pathetic, as reception on crystal-controlled opera- Itbecame inaudible when the volume with 15W input to the V10 Plate tion. As a result, I set the receiver up control was reduced to zero ald I sub- for best performance on the 2692kHz sequently found that better shielding circuit, the output should have been around the detector and noise limiter crystal-locked position with the (6AL\u00de) improved the situation. around 10W. The rated input to the signal generator, then switched to When the set is on vibrator supply, transmitter is 20W but I wasn't push- the tunable position and adjusted the oscillator slug until the 2692kJfz there is noticeable vibrator hash and ing itthathard with mytemporary link the use of the noise limiter is desir- signal was heard. I then did the same able. It's not the best noise limiter in coupling system. on 4510kH2, this time adjusting the oscillator trimmer. the world but it does work. The tralsmitter output stage doesn't siliconchip.com.au Overhauling the transmitter gain any accolades from me. The ratio Like the receiver, the transmitter had of the inductance and capacitalce in many leaky AEE capacitors that had to the tank circuit (PA output tuned cir- be replaced. And like the receiver, the cuit) is not correct across most of the resistors were all OK but just within band to which it tunes. Furthermore, tolerance. the link coupling method used for extracting the RF energy from of the tank circuit doesn't work efficiently in these transmitters. In my opinion, a better-designed output circuit would achieve an efficiency of 0o-0s% in the PA circuit. sc ocroBEn 2005 105","ASK SILICON CHIP LL0V transformer issue and I hope you could answer t\u00ece Loudspeaker Level Meter which for disc player some questions. I own a cocktail bar could then give art easy visual indi- I have a mini-disc player which is with some noise issues. I need a meals obviously made for USA and runs on to show the bands and Dls how loud cation. L10VAC. Is there any way this can be they are and a level not to go over. This used in Australia with some sort of meter seems ideal, apart flom being Sound level meters are available step-down device or voltage selector? from Altronics (Q-126a), Dick Smith (T. B., via emaill. too sensitive, Electronics (Q-1362) and laycar EIec- tronics (QM-1588). o ]aycar Electronics have a range of Could you teII me how to make it The Earth's magnetic 115V stepdown transformers which read louder noises and how to give field & CRT alignment? it a greater range for the LEDs? [P. L., will do the job. Mind you, some au- via email). I recently signed up to do an on-Iine dio equipment comes with a mains transformer with two 120V primary o If you want the level meter to re- course to obtain my amateur radio li- windings connected in parallel for spondto much louder sounds, youwill cense. As part of this course, there is an 115V operation. If you are competent need to reduce the sensitivity of the in this area, you could reconnect the on-line forum thatyou are encouraged first op amp stage. The easiest way to to join where questions and alswers primary windings in series for 240V do this is to increase the 100f) resistor may be posted (a newsgroup), operation, to 1kO or even 2.2k\u00e7\u00bf. However, it will Shortly after signing on, I read a If you are lucky, you may even find still only read over a 20dB range. that the internal wiring can be easily If you need to monitor sound levels message fiom a chap who had moved changed or there may even be an in- from England to Sydney and brought ternal switch. over much wider ranges, the only prac- his large, wide-screen Sony Trinitron colour TV with him, This TV set now Level meter tical way to is use a sound level meter. for cocktail bar has a colour registration problem. These have more than 100d8 of meas- I have just completed building the urement range. In fact, you may have The colours are all distorted (like you Loudspeaker Level Meter for Horhe held up an unshielded hifi speaker to Theatre Systems from the April 2004 a legal requirement (ie, WorkCover) to the side of the set). The fault is down both the left and righthand sides of the avoid exceeding certain sound levels tube and it looks like it badly needs and you may need a sound level meter to show that you are able to monitor degaussing. However the set's internal a\u00a1rd meet this requiremeit, degauss circuit does not seem to be able to conect the problem. The sound level meter could per- haps be used to set the sensitivity of So I sent a post to this chap suggest- H\u00fcmWWonFmAffihmdh\u00fc\u00fe ing that I thought his problem may be related to tlre Earth's magnetic field. In I have purchased a Universal tor. The 5V is connected to the point form my post basically said: High Energy ignition project, as HaII Signal input on the PC board. (r) That being in the IT industry I featured in the June 1998 issue of Ignore the HalI + and Hall GND was aware that computer monitors are SrLrcoN Cutp. I have had it for a connections. aligned\/manufactured for either the while and had planned to install The voltage sense foom the ECU southern or nortlrern hemispheres. it in my old car. However, I sold may be inverted so that the spark (z) I had seen first-hand an entire my old car and,have recently had occurs on a 5V to 0V transition, us- shipment of northern hemisphere col- our monitors shipped to Australia by the ignition module in my new car ing a transistor. To do this, remove mistake and that they all looked like they badly needed degaussing. fail. It is a Honda Prelude and from the 10kQ resistor connecting to (3) That while I had no first-hand what I have found out, the signal transistor Q2's base and connect a wire from the tachometer output at knowledge of TVs, that I assumed from the ECU is a 5V square wave. the collector of transistor Q3 to the that this problem would be inherent Is there a way to adapt the High base of Q2. to both monitors and TV sets as both Energy ignition for my application? Note that the collector of Q3 and fundamentally use a CRT, the base of Q2 connect to adjacent (D.W., via email). (a) That I suspected that his fault tracks on the PC board, so just o The High Energy Ignition can bridge these two tracks with a short may be a result of his TV being aligned by the manufacturer to the northern be operated from a 5V signal ifyou Iength of tinned copper wire, use the Hall Effect circuit without hemisphere's magnetic field charac- including the B20Q pullup resis- 106 SIUC)N CHIP siliconchip.com.au","teristics and that the fix may actu- uffiDGffiproffihffi ally involve realighment of the CRT. Referring to your Uiha-LD Preamp plies to the clipping indicator in I suggested that this was something & LED Display in the November the Ultra-LD circuit - it is not a that should not be attempted by the 2001 issue of SntcoN Crm, there precision circuit and it only gives inexperienced, as the end result would is a question that comes to mind. an approximate indication that This unit is checking the clipping most certainly be worse than the cur- points of IC1 and preceding equip- clipping is probably occurring if rent problem. ment rather than that of the power the topmost LED is alight. (5) That I thought the problem amplifler. Some clipping circuits (eg, page 72, November 2003 issue and the was probably related to the reason According to information I've why magnetic navigation compasses found on a website, Rod Elliott of one on Rod Elliott's website) assume (mostly the flat orienteering types) also ESP (http:\/\/sound.westhost.com\/ that if the signal rises to within 5V were manufactured differently for the projectZ3.htm) states that \\\"most or so of the positive or negative amplifier supply rail, the output northern a\u00a1rd southern hemispheres; clipping indicators published over ie, the pointer needle requires differ- the years rely solely on an attenu- transistors must be saturated and ated version of the output signal, ent counter balancing so that it rests supplied to a suitable comparator therefore clipping is occurring, horizontal to the Earth's surface and circuit. That worrld be fine if the However, it is still only an approxi- does not try to either point sk1'r,vard mation. In fact, Rod Elliott's circuit or down into the Earth. mains voltage stayed exactly the same at all times and if the power assumes that if the signal comes Within a short period of time, no less than two full-call amateurs had posted supply had perfect regulation. The within 3V of the supply rails, clip- rebuttals to the Forum. One was from one of the on-line facilitators for the fact is neither of these is true a\u00a1rd the ping is occurring. course I was now enrolled in who has amplifier's DC supply voltage can In most amplifiers with Mosfet a degree in electronics and electrical vary considerably fromhourto hour or emitter follower output stages (virtually all modern amplifiers), engineering, He summarised my entire and even minute by minute\\\". that would be fairly severe clip- post as \\\"Horse Excreta\\\" and categori- The clipping detector shown on ping since the output tuansistors are cally stated that \\\"no such manufac- the above website relies on one turing process exists\\\" in reference to typically saturated with a collector- my assertion that computer monitors factor (and again I quote): \\\"how emitter voltage of 6V or more. This were made for either the northern or is usually a limitation in the driver close to the supply voltage is the southern hemispheres. power amplifier's output signal at stages rather tha\u00a1r in the emitter He was so emphatic and obviously any instant in time. If and when tle follower output stage. We tried to knew more about the Earth's magnetic eliminate some of this drawback supply voltage varies, the detector field than I will ever know, that I am varies along with it and wiII detect by running high-voltage rails to now beginning to think that maybe the driver stages of the Ultra-LD even a very short peak that crosses I'm a fool who has been taken in by amplifier. a popular urban myth. So what is the the detection threshold\\\", This unit if you really want to produce an truth to all this? is connected across the power am- exact clipping circuit, you need to Are TV sets susceptible to the plifier's speaker terminals, precisely compare the input and Earth's magnetic field at all, in that output signals of the amPlifier, so I would appreciate it if you that even a small degree of clipping the alignment of the CRT must counter this field? Is the magnetic field in the would enlighten me on this matter can be detected. In practice though, northern hemisphere somehow differ- with regard to your circuit, (G. K., small degrees of clipping are very ent in nature to that in the southern Elizabeth, SAJ. difficult to hear on music signals hemisphere, thus requiring different and so most clipping indicator . It is true that most clipping in- circuits are quite adequate in this CRT alignments? dicators have a drawback because respect. And even if this is all true, was it the amplifier's supply rails are not reasonable to propose that the colour regulated. The same drawback ap- registration problem in question might An excerpt from http:\/\/repairfaq. multi=pole correction field. Then each be related to this effect? (S. ,t., via tube is matched with a deflection yoke ece. drexel. edu\/sam\/cr\u00faaq.htn#crhrsh to achieve optimum colour purity, It is email). fapparently from a Philips engineer) possible that a. couple of yokes must adds further to the above: be tried in succession. o You are absolutely correct and \\\"There are two types of adjust- This matching is done under sPe- your protagonists are utterly wrong. cific ambient magnetic field condi- ments: tions, On oriental tubes, you will often Large CRTs for TV and computer see little permanent magnets added (L). The passive ones tlat are done in to achieve further fine correction of monitor use are set up for northern or southern hemisphere use. Generally, the picture tube factory; and landing and\/or convergence, When the this is via a few small fixed magnets (2). The active ones that are done by on the yoke assembly. To change the tube is within landing speciflcation, it setup of a northern hemisphere set the set maker and\/or the customer. for the southern hemisphere probably is shipped to the set maker. In the factory, inside the neck of requires the services ofyour local Sony every fPhilips) tube, a metal ring is OcroBEn 2oo5 lo7 permanently magnetised to create a agent. However, the tube will also have to be .manually degaussed, siliconchip.com.au","mffiWAmpffi res&ffi I have constructed two SC480 am- amplifrer boards very carefully to Automatic Alternate Motor see that you have correctly installed plifier modules with TO-3 output all the transistors and diodes. Switch (Circuit Notebook), Sep- tember 2005: the pole of switch transistors (SnIcoN Crm, January tx In the case of your first amplifier S1a should connect to +12V via February 2003). One has burnt out module, it seems possible that you the contacts of the time clock, not may have inadvertently swapped to +5V as shown. the resistor between the base of Q9 and trimpot VR1. The resistor at the Q8 & Qg - this may have damaged Filter For Ripple Control Mains emitter side of Q6 has also gone. Tones, Circuit Notebook, Septem- both these and other transistors. ber 2005: WARNING: Do not use The other amplifier module is get- You won't know until you reas- this circuit. Due to a major over- ting B0+ volts across the 6.8Q resis- semble the module and re-check sight, this circuit was not tested at the voltages with the 560C) current- 240VAC which would have high- tor and will not allow the quiescent limiting resistors. lighted the following drawback. current to be adjusted, Transistors Q4, Q5 and Q6 are getting very hot. I Onthe secondboard, with Q4, Q5 Regardless of the values of have onlybeen doing electronics for the capacitors selected for the four months and would appreciate & Q6 overheating, it seems likely circuit, tleir reactance wiII be all the help you can give me, (R. J., via email), that you have inserted diode D3 the quite low resulting in the appli- wrong way ilound. Again, the tran- cation ofhigh voltage to the 2W \u00a1 You need to check both your sistors may have been damaged. potentiometer which will fail at switch-on. Depending on the sophistication These monitors should be mostly of the circuitry in the (television or replied to an inquiry about making a insensitive to the Earth's magnetic monitor) set, the set maker can adjust metal detector for use in woodwork- geometry ald sometimes convergence field. (This technology was originally [if there is a set of convergence coils invented for the use of CRT displays ing, saying that some detectors meant onboard jet fighter planes, which tend present), If there is a rotation coil to turn relative to the earth), for studs (and metal) could do the present, then this may also improve All other monitors will degrade job' the landing a bit. picture quality when the degaussing I agree and have several such detec- In \\\"digital monitors\\\", there are flex- is not able to completely compensate for the Earth's magnetic field, With a tors but the they require a lot of tedi- ible waveform generators to adjust ous close scalning. Could you point tube built for the wrong hemisphere, it the corrections. There may be further him to Carba-Tec NSW Pty Ltd, 1L3 adjustments possible for the uniforr\u00a1r- is possible that the effect of the verti- ity of the colour point and brightness. cal component of the Earth's magnetic Station Road, Auburn, NSW 2144. This gives a place-dependent modula- tion ofthe three beam currents; it does field will give a residual landing error, Phone 1800 683 583 and ask for Cat. nothing to improve the landing. This cannot be corrected by turning MMD2 and get a dedicated detector The most expensive monitors (large any of the available adjustments, dig- ital or not. Re-alignment mightbecome for $49.00, That's only $19 more than screen, fine phosphor pitch, very a very costly job,\\\" the g30 for the stud one. He could not critical on landing) may have ac- tive magnetic field compensation in Nail finder for build it for that! all three directions, with electronic woodworkers magnetic fleld sensors for automatic No, I do not belong to the flrm but In Ask SucoN Crur for August, you adjustment. I have bought a lot of stuff from them and they are very good. (1. W,, via email). SC WARNING! StLtcoN Cnre 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 w\u00a1th mains AC voltages or high voltage DC. lf 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 equip- ment. 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 con- form to theTrade Practices Acl 1974 or as subsequently amended and to any governmental regulations which are applicable. 108 StucoN Canp siliconchip.com.au","MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. I II III I IIIIIIIIIIIII I I-' -I I FOR SALE CIASSIFIED AOIIER1IilNE RA\u00eeES ! ROvertising rates for this page: Classified ads: $22.00 (incl. GST) for up to 20 words I MORE CONTROL SOLUTIONS \u00faor you: I plus 66 cents for each additional word. Display ads: $36.00 (incl. GST) per column I -Netiom Link automatically transfer I centimetre (max. 1Ocm). Closing date: five weeks prior to month of sale. I digital inputs and outputs between two I ad, print it cle I cards over an Ethernet link II rm&senditw I Labjack USB Data Acquisition Module I features 8 12-bit analog inputs, 20 d\u00edgital Box 139, Col I l\/O, 2 analog outputs and high speed counter. Free software DaqFactory I .end an ema Express, Labview driver and ActiveX component. I taxat\u00a1on lnvoice ABN 49 003 205 490 Signal Gonditioners non isolated II aRnTdDissoltaoted4--2OcomnvAerot rthe0r-m1o0cVo.upFleusll,y II programmable. II Pixel Programmable Controller with II 4 analog inputs, 8 digital inputs and II 8 relay outputs. Uses a Picaxe 28X. II Programmed in BASIC. Temperature and humidity sensors II N1500 universal process indicator. II Budget-priced displays thermocouple, RTD, 4-20m4 and 0-5V readings. Fully II programmable. II Box of Gonnectors - choose BNC, II U H F, N Type or RS232 gender changers II and converters together. Serial and Parallel port relay controller II cards. Pump andTr\u00a1p Alarm Controller card. II Duty-Standby operation. MicroProgrammers for Atmel and PIC II chips. 2, 4 & 8 Relay Cards suitable for TTL II and Open Collector Outputs DC, Stepper and Servo Motor controller II kits. Switch-Mode, Battery Chargers and II DC-DC converters. Fulldetails and creditcard ordering avail- II \u00a1Enclosedismycheque\/moneyorderfor$-orpleaSedebitmy I able at www.oceancontrols.com.au ! [ I Iaantcaro Visa Card Master Card I Helping to put you in control. II SILICON CHIP BINDERS. First edition rcardNo [[Tl[[Tl [[m[l-T-fl to end 2005. Offers to (07) 3201 4976 I incl packaging and freight. I RCS RADIO\/DESIGN is at 41 Arlewis \u00a1I Signature dateCard expiry \/ I I St, Chester H{l2162, NSW Australia t.. Name I and has all the published PC boards I from SC, EA, ETl, HE, AEM & others. I Ph (02) 9738 0330. sales@rcsrad\u00a1o. com.au, www.rcsradio.com.au I Street I I I OcroBER 2oo5 1og I Suburb\/town Postcode I I I wvvw s i Ii co n c h ip. co m. a u","TAIG MACHIIIERY Micro Mini Lathes and Mills From $489.00 Slimline Mini FM R\/C Receiver Send for your free \u00ednfo pack containing equip- O 6 Channels O 10kHz frequency separation ment catalog, satellite O Size:55 x 23 x 20mm O Weight:259m Stepper molors:200 oz in $89 00,330 oz in $110 00 O Modular Construction Digital verniers: 150mm $55 00, 200mm $65 00 Price: $A129.50 with crystal Crescent59 G\u00a1lmore 2605Garran ACT (02) 6281 5660 Itlr\u00e6\\\" Electronics 0412269707 P0 Box 580, Biverwood, llSW 2210. ELNEC IC PROGRAMMERS VIDEO . AUDIO . Ph\/Fax (02) 9533 3517 -distribution amps splitters Universal and email: youngbob@silveilone. com.au disgwitaitlchstearnsda-rdcsabcloensve-rtaedrsap-totbrsc's Website:www.silvertone.com.au s genlockers - scan converters -t,'',;;.. llllEslr0ilfr see products ond downlood \u00det\u00a1cel\u00a1st ot w.ques\u00faon\u00a1x.cffi ou \u00cdax (02]| \u00df4'l 2795 phone (02) 4343 1970 apto Free regular software updates Wi ndows 95\/98\/Me\/NT I 2W XP GRANTRONICS PTY LTD PO Box 275, Wentworthville. 2145. Ph:02 9896 7150 www.grantron ics.com.au Circuit Board Manufacture 48-Hour service * High quality * Low prices Foam surrounds,voice coils,cones and more I offs to any quantlty repairs0riginal parts for Dynaudio,Tannoy and others S\\\\\u00f0\\\\\\\\\\\\ ArT\u00a1rwoorkrKdqeessigl\u00a1grnilfrereqquurrireeqd \/ 7ow::*\u00ef:- Expert speaker experience www.fur\u00bfy,com,au Australian agentsfor products Callfor obligationJree quote...\u00da Ph 02 4579 7992 INSTANT PCBS, POBox 448, Avalon2 Trade welcome- emailforyour user lD Phone (03) 9641 7000 Voltmeter, l\/O Relay Card, USB via direction, inside temperature, outside temperature & windchill. Records highs speakenb i ts. corrr.aLr LabVlEW. Also available: Digital Oscil- & lows with lime and date as they occur. loscope, Temperature Loggers, VHF Optional rainfall and PC intedace. Used USB KITS: GPIB lnteface, Thermostat F\u00ececeivers and USB ActiveX (and US- by government departments, farmers, BDOS.exe file) to control our kits from pilots and weather enthusiasts. Other Tester, LCD Module lntedace, Step- models with barometric pressure, hu- per Motor Controller, PIO lnterface, your own application. www.ar.com. midity, dew point, solar radiation, UV aul-softmark leaf wetness, etc. Just phone, fax or write DTM F Transceiver, Thermometer, DDS for our FREE catalog and price list. Eco WEATHER STATIONS: windspeed & Watch phone: (03) 9761 7040;fax: (03) HF Generator, Compass, 4 Channel 9761 7050; Unit 5, 17 Southfork Drive, Kilsyth, Vic. 3137. ABN 63 006 399 480. NIIW SUPERBRIGHT LEDS from just 15 RfRUoAtItlABlE Proiect Beprints cents each, including new wide angle limited BacH Issues rangel 12 volt LED lightbars, great for limited One-Shots solar\/camping. Nixie tubes and nixie clock kits. Lots of other stuff , and always lf you're looking lor a project from ELECTRONICS AUSTRALIA, you'll f\u00a1nd it at SlLlC0N CHIP! We more items being added. New webshop now online! www.ledsales.com.au can now offer reprints of all proiects which have appeared in Eleclronics Australia, EAT, Electron- ics Today, ETI or Radio, TV & Hobbies. First search the EA website indexes lor the project you want S-Video . . .Video . . . Audio . . .VGA and lhen call, fax 0r email us with the details and your credit card details. Reprint cost is $8.80 per distribution amps, splitters, standards article (ie, 2-pail pr0iects cosl $17.60). SlLlC0N CHIP subscribers receive a 10% discounl. converters, tbc's, switchers, cables, etc, We also have limited numbers of EA back issues and special publications. Call for details! www. siliconch ip. com. au visil www. si I ico nch ip. co m. a u or 110 SntcoN Cntp","Do You Eat, Breathe and Sleep TECHNOLOGY? Advefiising Index for full-time and nart-time oositions all over Australia & New Zealand Jaycar Electron\u00a1cs is a rapidly growing, Auslralian Why not do something you love and get paid for \u00a1t? Please 555 E|ectronics.................. ..........52 owned, internat\u00a1onal retailer with more than 39 slores in write o\u00a1 email us w\u00a1th your deta\u00a1ls, along wilh your C.V. Auslralia and New Zealand.0ur aggressive expansion and any qualilications you may have. We pay a Amateur Scientist CD .............OBC programme has resulted in the need for dedicated compet\u00a1t\u00a1ve salary, sales commissions and have great individuals to ioin our leam t0 assist us in ach\u00a1eving oul benefits like a liberal staff purchase policy. Altronics ...........72-75 goals. Send to: Aspen 4mp|ifiers ....................... 1 1 1 We pride ourselves on lhe technical knowledqe of our Beta\u00a1l 0perations Manager - Jaycar Electronics Pty ltd stafl. Do you think that the lollow\u00a1ng statements descr\u00a1be P0. Box 6424 Silveruater NSW 1811 Av-Comm you? Please put a t\u00a1ck \u00a1n the boxes that do: Email: [email protected] .............110 E Nnowledge of electron\u00a1cs, particularly at Domponent level E Assemble projects or kits yourself for car, conputer, aud\u00a10, etc, Jaycar Electron\u00a1cs is an equal opportun\u00a1ty employer and Delta Audio... ............7 C Have empathy with others who have the same interest as you. activsly promotes staff lrom w\u00a1th\u00a1n the 0rganisat\u00a1on. Dick Smith Electronics .......... 16-21 O May have worked \u00a1n some reta\u00a1l already {not obligatoryl Jdgtrar O Have energy, enthusiasm and a personal\u00a1tV that eniovs Dominion Electronics ...........93,1 1 1 helping people. Eco Watch E Apprec\u00a1ates an opporlunity for future advancenent, E Have an eve lor deta\u00a1l ............1 10 ASI\\\\ Sanedlegcet tysoutramr\u00a1tcerodco.n..troller k\u00a1t EF|1.............. ..,.......51 Best high end DIY audio kits iffJ:1;' Elexol ........... ..........49 on the planet! ,*\/ )\u00ec 51'rT. :.nlh't Furzy E|ectronics....................... 1 1 0 w\u00eftw.aksaonl\u00a1ne.com Grantronics.. .........110 & price list: www.questron\u00a1x.com.au lmageCraft C Compilers: 32-bit ffimkc Harbuch E1ectronics ....................83 Windows IDE and comp\u00a1ler. For AVR, Feature r\u00a1(h, (0mp\u00eclef ed\u00ector & debugger I nstant PCBs ............................. 1 1 0 w\u00a1lh roy\u00e3lty feeT(P\/lP stack 68HC08, 68HC1 1 , 68HC1 2, 68HC1 6. Jaycar ...... lFC, 53-60,84,96,97,1 1 1 . Pd@s uftde\u00fasl and deliry\u00fba\u00cdq6. from $330.00 JED Microprocessors...............5,85 Atmel Flash CPU Programmer: Han- Tel: + 61 2 9906 6988 Fax: + 61 2 9906 7145 Laservision... ..,.......49 dles the 89Cx051, 89C5x, 89Sxx in www.dom in ion.net.au both DIP and PLCC44 and some AVR's, most 8-pin EEPROMS. lncludes socket Microgram Computers...................3 for serial ISP cable. $220, $11 p&p. WANTED MicroZed Computers...................79 SOIC adaptors:20 pin $132.00, 14 pin ANYONE INTERESTED in electronics Ocean Controls ......................... 1 09 $126.50, I pin $121.00. who wants to get together, and share ideas, knowledge and maybe work on Ozitronics .................7 Full details on web-site. Credit cards joint projects callWayne Bridgman (03) accepted. GRANTRONICS PTY LTD, 9882 6176, waynebr\u00a1dgman@gma\u00a11. Prime Electronics ........................85 PO Box 275, Wentworthville 2145. (O2) com 9896 7 1 50 or http:\/\/www.grantron\u00a1cs. Quest E|ectronics.................85,1 1 0 com.au KIT ASSEMBLY Radiometrix. ...........25 PCBs MADE, ONE OR MANY Any NEV\u00a1LLE WALKER KIT ASSEMBLY format, hobbyists welcome. Sesame RCS Radio ...........'110 Electronics Phone (02) 9593 1025. o& REPAIR: [email protected] Australia wide service RF Probes... ....,........7 www.sesame.com.au o Small production runs SC Ped Elect. For Cars......112,lBC o Specialist\\\"one-off\\\"applications SC Projects For Cars, Vo1.2.........25 Phone Neville Walker (07) 3857 2752 Email : f lashdog @optusnet.com.au Silicon Chip Binders ........49,52,1 1 1 Silicon Chip Bookshop .......... 98-99 Silicon Chip Subscriptions ..........37 Silvertone Electronics ...............1 1 0 Siomar Batteries .........................51 Speakerbits ..........110. * Heavy board covers with mottled dark green Taig Machinery.......................... 1 1 0 *vinyl covering Each binder holds up to 12 *issues SILICON CHIP logo printed on spine Telelink ...................85 & cover. PG Boards Price: $412.95 plus $A7 per order (Australia Printed circuit boards for SlLlcoN only; not available elsewhere). Buy five and get them postage free. CHIP projects are made by: RCS Radio Pty Ltd. Phone (02) 9738 Just fill in & mail the handy order form in this 0330. Fax (02) 9738 0334. issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. OcroBER 2oo5 777 www. s\u00a1 I\u00a1co nch ip. com. a u","From the publ\u00c8he\u00df ot u oa*n* a hanorc u,' ,,-.. frifoiu'sEe'nig\u00e5u'\\\"o$\\\":\u00a1s\\\"3l3l:ll\\\"n' ,. \\\"'s\\\"'o'f.T*' \u00eelg\u00a151.3 ;$lJ\u00ce.\u00cc\\\",:.1'l'\u00f1\u00e5l?'$ fl:\\\"i:\\\"lJ,.\\\"'ii3:l[-:\\\"il:s,l*:-::\u00cf*'*\\\"\\\" ^;;i\\\"idl:t'Jr,\u00e4\\\"nJfi ,.*ffi - \\\"&:':1\\\"'\\\":'lJ\u00ec':'\u00ecv*'lu\\\"'lx?'*o'n''u'u' il,gJr$ft .?l'..8'\\\"'\\\"J'\u00cd:\u00ce;:'llfl'o;T\u00e51\\\"i,,-. I *i\u00ee\u00eetl*l,lslg'*nrS3'l''\\\"'l'\u00ee3f SJ*fnctron\u00ecccircuits *re's how to measure \u00e7nf'l',t*.zu o\\\"*'l'ty#l''1fi.\u00e5?: .ii\u00e3nlun\u00bf resistance a ll0l a relrlnt - nBu, DrolEcls am anilcles nol - tY, ** :.:,::\u00ee::'** .:. S r\\\"\u00cb\u00cb*J\u00e5if,,,'nrffi M DUDI\u00a1$nBd DCl0nc at o teann nou, cng\u00a1ne managBmGnl u,0rils o B\u00fclld ln0iects t0 Gontnol n\u00a1l\u00eeo\u00fcs, lusl \u00a1nlcctlon an[ lunm D00$t $ustems o surltcn dcu\u00a1Ges 0n and 0ll0n tne ms\u00a1$ 0f $lgnal fre0uencu, lem[GFal\u00fcFe and u0llag8","82 CHAPrER 1LI\\\"J:,lq\u00cf,\\\"' l,.\\\"\u00e5:\u00cb'i\\\"'l ?l'l$io,il\u00e4lJN:lT.lt,of\\\"I\u00e99P1\\\":or\u00cf'\\\"'l'\\\"\u00e5:\u00cb'i:iitchdevicesonandotr il;;;86 i)\u00ef'\u00e5lfrt\u00eeJJF'.#l-\u00bfi;*.'Ju; ::,f.p,ul'^.r1e\u00eel\u00e7rd,5r.ivi\u00eflioln'e,i\u00ec:\u00ec$\u00e5,':.:','o'Jn1\u00e6\\\"\u00e5\u00bfl \\\"'t't,' based on how stsaetedlePrsionulgelnsaoesidsAst,stn{to^iuy\\\"u'\\\"tuf't-\\\"r\\\",J,\u00e0n-troutr.ani\u00a1ieoxtr\\\"du\u00e6@ , ^*^' Dn\u00ec\u00ec\u00f8gititaarrttuer 105 \u00ca\u00fe\u00ef!\\\"..,l,.l:,?\u00ca:*\u00e5i:i\u00e5'i;,\u00ec:.' {\\\\ do-a'1PoJt;ot\\\"r'need\u00a1 +thhiisc \u00f3\u00ec*i\u00e4i\u00c9urtt \u00a1oiu\\\"tt lt6 to'ao\u00a1u* arlu4 railos' even change c t\\\"l supprv or even iust to '3'\\\"'illt$l;'\u00ed' I\\\",J.!$\\\"H:I match how hard vou've ffiili-tx.on drivtnB Resistor & capacitor G .\u00e81 Tffil'F:ii\\\".i'\\\" TOR CARS ELECTRONICS PERIORMANCE ,f#ff*\\\"\u00e9\u00cb'\u00effi*'i-o'so s\u00ecliconchip com au sil\u00ecconchiP com au Pn\u00a1ce: Aust. $A?2.\u00f50 finol. osl & D&D): 0u8r$Eas $f,20.00 (lncl. 0&D u\u00a1a a\u00a1nmaill. silrcon l\u00a1nlI Pullical\u00a10ns Plu lld' P0 80il 139 Cllllanou, llsll,, Au$tlalla 2097. Pn0ns (02) 9979 564[: tA[ (02) 9970 6503. EmAll SilCnlD@sll\u00a1c0nGni\u00a1l.G0m.au","Two incredible CDs with over 1000 classic projects from the. pages of $cientif ic .American covering euery f ield of scieJtce. .. Arguably THE most IMPORIANT collection of scientific proj 1*.( ever put together! This is version 2, Science Fair Edition from the pages of Scientific American. As well as specific project material, the CDs contain hints and tips by experienced amateur scientists, details on building scie alarge database of chemicals and so muc \\\"A must for every science student, scienc teacher, science lab . . . or simply for tho with an enquiring n\u00f9nd . . .\\\" \\\"-: c\/','g{F- -\u00e8-- Just a tiny selection ofine 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. lnvestigate vortexes in water. Cultivate slime moulds . Study the flight etficiency 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 review in StttcoN CHtp, October 2004. . . or read on l\u00a1ne at IIERE'S }TOW \u00cdO ORDER YOUR COPY: - Please have your credit card handy! # Don't forget to include your name, address, phone no and credit card details. ^ You will be prompted for required inlormalion Thete's also a handy order form inside this issue (see Stucoru Cxlp Boolrshop pages). .silrconcnr .co .au"]