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ELECTRONWORLD

JANUARY 2003 £3.25

An alternativeimpedancemeasurementpart 2Capacitorsound part 6

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Te netHewlett Packard 3314A Function Generator 20MHz £1250Hewlett Packard 3324A synth. function/sweep gen. (21MHz) £2250Hewlett Packard 3325B Synthesised Function Generator £3250Hewlett Packard 3326A Two -Channel Synthesiser £3000H.P. 4191A R/F Imp. Analyser (1GHz) £4995H.P. 4192A L.F. Imp. Analyser (13MHz) £4000Hewlett Packard 4193A Vector Impedance Meter (4-110MHz) £3000Hewlett Packard 4278A 1kHz/1MHz Capacitance Meter £3750H.P. 53310A Mod. Domain Analyser (opt 1/31) £6750Hewlett Packard 8349B (2 - 20 GHz) Microwave Amplifier £2500Hewlett Packard 8904A Multifunction Synthesiser (opt 2+4) £1950H.P. ESG-D3000A 3GHz Signal Gen £6995Marconi 6310 - Prog'ble Sweep gen. (2 to 20GHz) - new £2500Marconi 2032 10Khz-5.4GHz Sig. Gen. £6995Marconi 6311 Prog'ble sig. gen. (10MHz to 20GHz) £2995Marconi 6313 Prog'ble sig. gen. (10MHz to 26.5GHz) £3750R&S SMG (0.1-1GHz) Sig. Generator (opts B1+2) £2750Fluke 5700A Multifunction Calibrator £12500Fluke 5800A Oscilloscope Calibrator £9995H.P 3458A DMM (8.5 digits) £3750Tek 371A Programmable Curve Tracer £15000

OSCILLOSCOPESGould 400 20MHz - DSO - 2 channelGould 1421 20MHz - DSO - 2 channelGould 4068 150MHz 4 channel DSOGould 4074 100MHz - 400 Ms/s - 4 channelHewlett Packard 54201A - 300MHz DigitizingHewlett Packard 54502A - 400MHz - 400 MS/s 2 channelHewlett Packard 54520A 500MHz 2chHewlett Packard 54600A - 100MHz -2 channelHewlett Packard 54810A 'Infinium' 500MHz 2chHitachi V152N212N222N3028/V302FN353FN5508V650FHitachi V1 100A - 100MHz - 4 channelIntron 2020 - 20MHz. Dual channel D.S.O (new)lwatstu SS 5710/SS 5702 -Kikusui COS 5100 - 100MHz - Dual channelLecroy 9314L 300MHz - 4 channelsMeguro MSO 1270A - 20MHz - D.S.O. (new)Philips 3295A - 400MHz - Dual channelPhilips PM3070 - 100MHz - 2 channel - cursor readoutPhilips PM3392 - 200MHz - 200Ms/s - 4 channelPhilips PM3094 - 200MHz - 4 channelTektronix 468 - 100MHz D.S.O.Tektronix 2213/2215 - 60MHz - Dual channelTektronix 2220 - 60MHz - Dual channel D.S.OTektronix 2221 - 60MHz - Dual channel D.S.OTektronix 2235 - 100MHz - Dual channelTektronix 2245A - 100MHz - 4 channelTektronix 2430/2430A - Digital storage - 150MHzTektronix 2445 - 150MHZ - 4 channel +DMMTektronix 2445/2445B - 150MHz - 4 channelTektronix 2465/2465A /2465B - 300MHz/350MHz 4 channelTektronix 7104 - 1GHz Real Time - with 7A29 x2, 7810 and 7815Tektronix TAS 475 - 100MHz - 4 channelTektronix TDS 310 50MHz DSO - 2 channelTektronix TDS 520 - 500MHz Digital Oscilloscope

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SPECTRUM ANALYSERSAdvantest 4131 (10kHz - 3.5GHz)Advantest/TAKEDA RIKEN - 4132 - 100KHz - 1000MHzAnritsu MS2613A 9kHz - 6.5GHz Spectum AnalyserAndo AC 8211 - 1.7GHzAvcom PSA-65A - 2 to 1000MHzFarnell SSA -1000A 9KHz-1GHz Spec. An.Hewlett Packard 182T Mainframe + 8559A Spec.An. (0.01 to 21GHz)Hewlett Packard 853A Mainframe + 8559A Spec.An. (0.01 to 21GHz)Hewlett Packard 3582A (0.02Hz - 25.5kHz) dual channelHewlett Packard 3585A 40 MHz Spec AnalyserHewlett Packard 3561A Dynamic Signal AnalyserHewlett Packard 8560A (50MHz-2.9GHz) High performance with TrackingGenerator option (02)Hewlett Packard 8567A -100Hz - 1500MHzHewlett Packard 8568A -100kHz - 1.5GHz Spectrum AnalyserHewlett Packard 8590A (opt 01, 021, 040) 1MHz-1.5MHzHewlett Packard 8596E (opt 41, 101, 105,130) 9KHz - 12.8GHzHewlett Packard 8713C (opt 1 El) Network An. 3 GHzHewlett Packard 87138 300kHz - 3GHz Network AnalyserHewlett Packard 8752A - Network Analyser (1.3GHz)Hewlett Packard 8753A (3000KHz - 3GHz) Network An.Hewlett Packard 8753B+85046A Network An + S Param (3GHz)Hewlett Packard 8754A - Network Analyser 4MHz -1300MHz)Hewlett Packard 8756A/8757A Scaler Network AnalyserHewlett Packard 70001A/70900Af70906A/70902A/70205A - 26.5 GHzSpectrum AnalyserIFR A7550 - 10KHz-GHz - PortableMeguro - MSA 4901 - 30MHz - Spec AnaylserTektronix 492P (opt1,2,3) 50KHz - 21GHzWiltron 6409 - 10-2000MHz R/F AnalyserTektronic 2782 (100Hz-33GHz) Spec. An.

Quality second -usertest 8t measurementequipment

Radio Communications Test SetsAnritsu MT 8801C Radio Comms Analyser 300kHz - 3GHz (opt 1,4,7) £6500Hewlett Packard 8920B (opts 1,4,7,11,12) £6750Marconi 2955 £1250Marconi 2955A £1750Marconi 2955B/60B £3500Marconi 2955R £1995Racal 6111 (GSM) £1250Racal 6115 (GSM) £1750Rohde & Schwarz CMD 57 GSM test set (opts B1/34/6/7/19/42/43/61 £7995Rohde & Schwarz CMT 90 (2GHz) DECT £3995Rohde & Schwarz CMTA 94 (GSM) £4500Schlumberger Stabilock 4031 £2750Schlumberger Stabilock 4040 £1300Wavetek 4103 (GSM 900) Mobile phone tester £1500Wavetek 4106 (GSM 900, 1800, 1900) Mobile phone tester £2000

MISCELLANEOUSBallantine 1620A 100Amp Transconductance AmplifierEIP 545 Microwave Frequency Counter (18GHz)EIP 548A and B 26.5GHz Frequency CounterEIP 575 Source Locking Freq.Counter (18GHz)EIP 585 Pulse Freq.Counter (18GHz)Fluke 6060A and B Signal Gen. 10kHz - 1050MHzGenrad 1657/1658/1693 LCR metersGigatronics 8541C Power Meter + 80350A Peak Power SensorGigatronics 8542C Dual Power Meter + 2 sensors 80401AHewlett Packard 339A Distortion measuring setHewlett Packard 436A power meter and sensor (various)Hewlett Packard 438A plower meter - dual channelHewlett Packard 3335A - synthesiser (200Hz-81MHz)Hewlett Packard 3457A muli meter 6 1/2 digitHewlett Packard 3784A - Digital Transmission AnalyserHewlett Packard 37900D - Signalling test setHewlett Packard 34401A MultimeterHewlett Packard 4274A LCR MeterHewlett Packard 4276A LCZ Meter (100MHz-20KHz)Hewlett Packard 5342A Microwave Freq.Counter (18GHz)Hewlett Packard 53508 20KHz Microwave Freq.CounterHewlett Packard 5385A - 1 GHz Frequency counterHewlett Packard 6033A - Autoranging System PSU (20v -30a)Hewlett Packard 6060A and B Electronic Load 300WHewlett Packard 6622A - Dual 0/P system p.s.0Hewlett Packard 6624A - Quad Output Power SupplyHewlett Packard 6632A - System Power Supply (20v -5A)

£3750 Hewlett Packard 8350B - Sweep Generator Mainframe£1350 Hewlett Packard 8642A - high performance R/F synthesiser (0.1-1050MHz)

£4950Hewlett Packard 8656A - Synthesised signal generatorHewlett Packard 65B - d gnal en

£1500 Hewlett Packard 8 86576A- Synth.SynthesisSigesignalsiGengen. (0g .1

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r)£750 Hewlett Packard 8657B - 1 -

£1250 Hewlett Packard 8657D - XX00MHzDQPSK Sig Gen£2000 Hewlett Packard 89016 - Modulation Analyser£2500 Hewlett Packard 8903A, B and E - Distortion Analyser£1500 Hewlett Packard 11729B/C Carrier Noise Test Set£3000 Hewlett Packard 53131A Universal Frequency counter (3GHz)£3500 Hewlett Packard 85024A High Frequency Probe

Kelhley 228A Prog'ble Voltage/Current Source IEEE.Ke thley 237 High Voltagel- Source Measure Unit

£5500 Ke thley 238 High Current - Source Measure Unit£3400 Ke thley 486/487 Picoammeter (+volt.source)£3500 Ke thley 8006 Component Test Fixture£2500 Marconi 2840A 2 Mbit/s Transmission Analyser£9950 Marconi 6950/6960/6960A/6970A Power Meters & Sensors£6000 Philips 5515 - TN - Colour TV pattern generator£5000 Philips PM 5193 - 50 MHz Function generator

£4995Phillips PM 6654C System Timer CounterSig. Gen. (100KHz-140MHz) AM/FM/CW

£3250 Rohde & Schwarz FAM (opts 2,6 and 8) Modulation Analyser£6500 Rohde & Schwarz NRV/NRVD Power meters with sensors£1500 Schlumberger 1250 Frequency Response Analyser

from £900 Tektronix 1720 VectorscopeTektronix 1735 Waveform Monitor

£7000 Tektronix AM503 - AM503A - AM503B Current Amp's with M/F and probe

£1750 Wavetek 178 Function generator (50MHz)

£600Wayne Kerr 3245 - Precision Inductance AnalyserBias unit 3220 and 3225L Cal.Coil available if required.

£3500 Wayne Kerr 3260A + 3265A Precision Magnetics Analyser with Bias Unit£1250 Wayne Kerr 6245 - Precision Component Analyser£9995 W&G PCM-4 PCM Channel measuring set

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JANUARY 2003 VOLUME 109

3 COMMENTSpecialisation and availability

5 NEWS Researchers weld nanotube Micromachines go nuclear PC is hi-fi

UK firms lagging in R&D $2m for roll -up display Single -photon secret keys sent 20Km

US firm makes GaN breakthrough Les Paul goes digital Fluids replace electricty Cars to get fast comms Smallest computer uses molecules

I 12 AIR TRAFFIC CONTROLIn the light of recent disasters, Nigel Cook has afew suggestions

NUMBER 1801

16 TAITRONICS TAIWANWe report on the latest electronic developmentsin the Far East

18 MODERN IMPEDANCEMEASUREMENT TECHNIQUESAlan Bate plots the demise of the twiddly knobbridge

27 NEW PRODUCTSThe month's top new products.

34 CIRCUIT IDEAS Simple stepper -motor Precision full -wave rectifier Simple bar graph USB-powered high -precision hi-fi

phono preamp

40 LETTERS Valve amp protection Cable testing Vibration meter Non -ionising radiation No Conspiracy Spectrum pricing

44 CAPACITOR SOUNDIn Cyril Bateman's final article he considersthe 10-100mF range

WEB DIRECTIONSUseful web addresses for electronicsengineers.

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DisclaimerWe work hard to ensure that theinformation presented in Electronics Worldis accurate. However, Electronics World'spublisher - Highbury BusinessCommunications - will not takeresponsibility for any injury or loss ofearnings that may result from applyinginformation presented in the magazine. Itis your responsibility to familiarise yourselfwith the laws relating to dealing with yourcustomers and suppliers, and with safetypractices relating to working withelectrical/electronic circuitry - particularlyas regards electric shock, fire hazards andexplosions.

Electronics World is published monthly.Orders, payments and generalcorrespondence to Jackie Lowe,Highbury Business Communications,Anne Boleyn House,9-13 Ewell Road, Cheam,Surrey, SM3 8BZ.

Newstrade: Distributed by COMAG,Tavistock Road, West Drayton, Middlesex,UB7 7QE Tel 01895 444055.Subscriptions: Wyvern Subscription

Specialisation and availabilityWhen I was an undergraduate, inthe late 50s and early 60s, allengineering students (with the

exception, if I remember rightly, of theaeronauticals and the chemicals) took thesame course in the first year. So we allstudied thermodynamics, strength ofmaterials, dynamics of fluids, theory ofstructures and metallurgy, as well aselectrical engineering. This broad syllabuswas both interesting and stimulating, andsome has stuck permanently. If ever I hadto calculate the flow versus height over agiven Vee-notch weir (can't remember offhand whether I need Francis' formula ord'Arcy's formula), I could still do so as theappropriate textbook is residing awaiting(improbable) use, in the technical section ofmy library. In the later years of the course,the content of the maths curriculum wasidentical to that of the Honours Mathssyllabus, except that we made do with "... itcan be shown that..." rather than proving allthose results in full mathematical rigour.

The situation is very different nowadays,since the frontiers of knowledge haveexpanded so enormously. Such a broadlybased foundation is considered anunaffordable luxury. It is now thought that,to be useful to an employer and hencesecure a job, a new graduate mustspecialise - not in electrical, or some otherbranch, of engineering. Not even in lightversus heavy electrical engineering, but in asmaller field still - telecommunications forexample. Presumably the heavy electricalshave also partitioned themselves into eversmaller specialisms, while variousuniversities, some redbrick, some evennewer, offer specialised degrees in a varietyof arcane subjects, from the infamous`media studies' to others as bizarre asAfrican tribal art.

So does the newly qualified telecomms(or whatever) engineer emerge with exactlythe right toolkit of knowledge to fit into aresearch or development job like a roundpeg in a round hole? The answer of courseis no. The syllabus is never really up todate: when I graduated in 1961, there wereplenty of valves in the syllabus, but nosemiconductors. I gather that syllabuses arenowadays not quite as far behind the timesas that nowadays, but the technology moveson remorselessly and the new graduate,assuming he is lucky enough to find anemployer, is likely to find himself facedwith a fairly steep learning curve, despite

the best efforts of universities. Theinadequacies of the syllabuses are generallyrecognised, even by politicians, so theymust be glaring indeed! For example, theUK government (or, to be more specific,the Department of Trade and Industry)sponsored over the last few years, theRadio Frequency Engineering EducationInitiative, in an attempt to alleviate thedearth of competent RF engineers face byan industry busy with Bluetooth, IEEE802.11a, b, c, and g, HomeRF, WLANs ofall sorts, etc. Having been involved withthe Initiative, I know from first hand thatcurrent electronics courses are completelydeficient in practical hands on work withreal live components and circuitry - it is somuch easier to sit a student down in frontof a PC and tell him to work through theexercises with SPICE.

Not surprising, then, that employers arealways looking for engineers alreadyexperienced in whatever happens to be theirparticular line of product development.Some firms, only the largest and then notalways, are willing to take on the raw newgraduate, and let him build up hisexperience base to the point where he ispositively contributing to the firm'sadvancement. But a glance at therecruitment ads in the 'freebies' (controlledcirculation magazines) shows that mostfirms seek to obtain their experience staffby recruiting from other firms, who then,naturally, feel forced to poach engineers intheir turn.

The problem is, of course, the lowesteem in which engineers are held; not bythe general public - who cares about that -but by employers. And let's be honest,esteem is a quality that can be accuratelymeasured - in pounds sterling.

Ian Hickman

ErratumKeen readers have noticed that in Colin Attenborough'sarticle 'Wide digital i/o from the USB port' in Novemberwe refer to a disk - insinuating that a CD should have beenstuck to the front cover. Whilst we do intend to put a CDon the front that will include this and other software, theincorrect version of the article was published. If any readerwould like the software, please email or write to JackieLowe at the addresses on this page with TSB' as thesubject and let her know what your preferred method ofdelivery is i.e. the whole thing in one email (6.5MB) orsplit into 2 meg chunks - or indeed a CD. Apologies toColin and interested readers. - Ed.

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January 2003 ELECTRONICS WORLD

I3

imminVISAQuasar Electronics Limited Add £2.00 P&P to all UK orders. 1st class recorded - £4.

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Rolling Code 4 -Channel UHF RemoteState -of -the -Art. High secu-rity. 4 channels. Momentaryor latching relay output.Range up to 40m. Up to 15Tx's can be learnt by one Rx(kit includes one Tx but moreavailable separately). 4 indicator LED 's. Rx:PCB 77x85mm, 12VDC/6mA (standby)Kit Order Code: 3180KT - £41.95Assembled Order Code: AS3180 - £49.95

Computer Temperature Data Logger4 -channel temperature log-ger for PC serial port. Deg.C or F. Allows continuouslogging of 4 separate sen-sors located 200m+ fromboard. Wide range of free

software applications for storing/using data.PCB just 38x38mm. Powered by PC. In-cludes one DS1820 sensor and four detach-able header cables.Kit Order Code: 3145KT - £23.95Assembled Order Code: AS3164 - £29.95Additional DS1820 Sensors - £3.95 each

Telephone Call LoggerStores over 2,800 x 10 digitDTMF numbers. Recordsall buttons pressed during acall. The time and date alsorecorded. No need for anyconnection to a PC during operation butlogged data can be downloaded into a PC viaa serial port and saved to disk. Includes aplastic case 130x100x3Omm. 9-12VDC.Kit Order Code: 3164KT - £54.95Assembled Order Code: AS3164 - £59.95

Serial Isolated I/O ModulePC controlled 8 -RelayBoard. 115/250V relayoutputs and 4 isolateddigital inputs. Useful ina variety of control and

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Infrared RC Relay Board12 -channel relay board. Eachrelay individually controlledwith included infrared remotecontrol unit. Toggle or mo-mentary. Over 15m range. PCB: 112 x122mm, Power: 12VDC/500mAKit Order Code: 3142KT - £44.95Assembled Order Code: AS3142 - £64.95

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ATMEL 89xxxx ProgrammerUses PC serial port. Nospecial programmingsoftware required. 4LED's display the status.ZIF sockets not included. 16VDC.Kit Order Code: 3123KT - £29.95Assembled Order Code: AS3123 - £39.95

P16Pro PIC ProgrammerSuper low cost programmerfor 8/18/28/40 pin DIP serialPICs including 16F84 &12C508. Software needs tobe registered @ £20.95. 17-

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ATMEL AVR ProgrammerProgrammer for 20 and 40 pin DIP(AT90Sxxxx) "AVR" micro controllers. UsesPC serial port. No special software required.ZIF sockets not incl. 16VDC.Kit Order Code: 3122KT - £24.95Assembled Order Code: AS3122 - £29.95

These modules use a microcontroller andcrystal for accurate and low-cost. 4 digit14mm LED display used on all but 3141.

Presettable Down CounterStarting count can be set. The4 -digit counter has fourmodes to control how theoutput behaves when itreaches zero. Max count rateof 30/sec or 30,000/sec. PCB:51x64mm. 9-12VDC.Kit Order Code: 3154KT - £13.95Assembled Order Code: AS3154 - £22.95

4 -Digit Timing ModuleThe firmware included withthis motherboard kit is aprogrammable down timer of10,000 sec. Timing accu-racy: 0.04%. PCB:51x64mm. 9-12VDC Cur-rent: 50mA. 5 other firmwarechips can be used with this

motherboard. Each has a different timingmode and can be purchased as a pack.Kit Order Code: 3148KT - £9.95Assembled Order Code: AS3148 - £18.955 Piece Firmware Pack: F3148 - £14.95

Multi Mode Universal TimerSeven different tim-ing modes in one!Modes and delayranges are set byDIP switches. Tim-ing delays range between 255sec (1secsteps) and 42.5h(10min steps) Mains ratedrelay output. PCB: 48x96mm. 12VDCKit Order Code: 3141KT £14.95Assembled Order Code: AS3141 - £21.95

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4

Researchers weld nanotube for first timeResearchers at the RensselaerPolytechnic Institute in New YorkState have discovered how to weldtogether single -walled carbonnanotubes.

Professor Pulickel Ajayan withcolleagues in Germany, Mexico,Belgium and the UK used irradiationand heat to form the weldedjunctions.

This is the first time single -wallednanotubes have been weldedtogether, although multi -wallednanotubes with junctions previouslyhave been created using growthtechniques, said the Institute.

"No one knew if junctions couldbe created," said Ajayan. "Single -walled carbon nanotubes are perfectcylinders without any defects, but to

create junctions between them, inter -tube carbon -carbon bonds need toform. The irradiation and heatingprocess we use creates just enoughdefects for these bonds to formwithout damaging their electricalproperties."

The process still relies on locatingnanotubes which cross with the rightorientation from a tangled nest asnanotubes can still not be made toorder.

The researchers used a specialelectron microscope in Stuttgart thathas the capability to irradiate andproduce the heat necessary for theexperiment, one of only a fewworldwide that can do this.

Ajayan, with GanapathiramanRamanath, also recently made some

Micromachines go nuclearCornell University has built a novelnuclear power source that could supplypower for decades.

The device uses a thin-film of beta -emitting isotope held parallel to aflexible springboard -like cantilever, allin a vacuum.

Beta particles are electrons and theseelectrons charge the springboard untilit bends by electrostatic attraction totouch the emitting layer. The systemthen discharges and the board springsback.

Researchers propose extractingenergy as electrical pulse, mechanicalmovement through a micromachine orby induction with a magnet attached tothe spring.

Several prototypes have been madeincluding one with a piezoelectricspringboard to generate power.

The prototype shown is made up of acopper springboard 1 mm by 2cm and60tim thick cantilevered over a thinfilm of nickel -63 with a half-life over100 years.

The entire device could eventually befitted into one cubic millimetre saidCornell.

What Cornell fails to say in itsannouncement is why it doesn't justcollect the electrons in a capacitor anduse this energy. As there are nophysicists at Electronics World, we arerelying on our readers to explain themerits or otherwise of this approach.

unusually large super -hard crystalsof boron carbide. The crystals havefive -fold crystallographic symmetry- also called icosahedral.

This shape is common innanocrystals, but micrometre-sizedicosahedral crystals are rare innature because their smaller unitscannot repeat their pattern infinitelyto form space -filling structures, saidAjayan. As the nuclei of thesecrystals grow, the strain on thecrystals increases. This usuallycauses them to revert to theircommon bulk crystal structures.

Ajayan believes that the inherentstructure of boron carbide, which hasicosahedral units in the unit cell,allows the crystals to grow to micronsize without the strain. Nanocrystals

Samsung has made a prototype46 -inch active matrix colourLCD. The panel is suitable forhigh -definition TV, with1,280x720 pixels, a 12msresponse time, 16:9 aspect ratioand 170° viewing angle in alldirections. Colour saturation is72 per cent (against the NTSCstandard) and contrast ratio isclaimed to be 800:1. Samsungmade the display at its fifth -generation line in Chonan,Korea which runs 1.1x1.25msubstrates - big enough for two46in panels. Mass production of46 -inch panels is expected inthe first half of 2003.

.01pmempoimmium,,January 2003 ELECTRONICS WORLD 5

UPDATE

PC is hi-fiTaiwanese PC motherboard makerVIA Technologies has produced ahome PC prototype that doubles as adomestic hi-fi and entertainmentcentre.

VIA calls the concept 'Hi-Fi PC'."While there are devices on the

market that fulfil some of theserequirements, the Hi-Fi PC is the firstsystem to offer the best of bothworlds, and completely embodies allthe expectations of consumers for aliving -room based device," saidWenchi Chen, president and CEO ofVIA.

Operating as a hi-fi, the19x19x34cm device powers -up in afew seconds because its operatingsystem is stored in the motherboardflash memory alongside the bios.

In this mode it plays all of the latestdigital video and audio formats underthe command of its remote control,said VIA, including CD, DVD andVCD.

The remote control also switchesmode between hi-fi and PC.

As a PC it boots running WindowsXP and along with its audio andvideo interfaces, come fast Ethernet,USB 2.0 and IEEE 1394 (Firewire).There is also a TV -out.

Universities gang up for f4mFive UK universities are to benefit from atechnology fund established by consulting firmGenerics.

Surrey, Sussex, Reading, Brunel and RoyalHolloway universities will be able to access the£4m fund in order to exploit their innovationsand developments.

Two tiers of investment are available from thefund. The stimulus tier is aimed at very early,high risk ideas. Up to £30,000 is available.

A growth tier is intended for less speculativedevelopments, and up to £250,000 can beoffered.

Behind the concept is amotherboard VIA is introducing tothe UK in the near future.

Measuring just 17cm x 17cm, theVIA EPIA M is based around thecompany's Apollo CLE266 chipsetwith an integrated MPEG-2 decoderand 2D/3D graphics.

For licensing reasons the baremotherboard is unlikely to beavailable with hi-fi capability.

VIA will be working with industrypartners to introduce Hi-Fi PCsystems to the market in the firstquarter of 2003.

$2m for roll -up displaysUniversal Display Corporation has gota two-year $2m research contract fromthe US Army Research Laboratories toco -develop technology to produceflexible OLED displays andcommunication components. Theprogram will focus on components forwhat the company calls a universalcommunication device (see photo).The device has an extendable or roll-out flexible OLED display and thecapability of a mobile phone.

UK firms lagging inUK firms continue to lag behind USfirms in the amount of revenue theyplough back into research anddevelopment, according to theGovernment's R&D Scoreboard.The report found that the UK investsin R&D above international levels inthe sectors of pharmaceuticals,biotechnology, aerospace, defenceand health, but below internationallevels in other sectors, includingelectronics.

Even so, average UK R&Dinvestment is rising, said the report,from 1.8 per cent in 1998 to 2.2 per

R&Dcent in 2002. US spending on R&Dhas remained constant at 4.3 per cent."This Scoreboard once againhighlights the importance of R&D toa company's long term growthstrategy. Taking full advantage ofscience and innovation is crucial todriving up productivity andgenerating wealth," said Trade andIndustry Secretary, Patricia Hewitt.

The report's author, Dr Mike Tubbs,concluded that firms concentrating onsustained growth and R&Dinvestment were more likely to see areturn for their shareholders.

6 ELECTRONICS WORLD January 2003

UPDATE

Single -photon secret keys sent over 20KmResearchers from UK research labQinetiQ and Ludwig MaximilliansUniversity in Munich have sentsingle -photon cryptographic keysover a world record 23.4km in theGerman Alps.

The system, set up between themountains of Zugspitze andKarwendelspitze, was based onequipment demonstrated over 1.9kmlast year at QinetiQ in Malvern.

Two telescopes provided thetransmit and receive optics, and thesewere coupled to Munich -developedminiature versions of the originalMalvern transmitter and receiver.

The scheme works by setting thepolarisation of a burst of laser light toone of four polarisations, thensending it to the receiver. Encodingand decoding is through fairlystandard electro-optical techniques.

This transfer method would not besecure if the whole burst of light wassent as it could be eaves dropped by athird party without anyone elsenoticing.

To prevent this, the burst is passedthrough multiple attenuating filters inthe transmitter to remove most of thephotons.

In fact, so much attenuation isapplied that, on average, only onephoton leaves for every ten bursts.

Through its quantum behaviour asingle photon cannot be detectedwithout changing it, so undetectedeaves dropping is impossible.

As all the attenuation means nineout of ten bits of data never actuallyleave the transmitter, it is essential forthe receiver to tell the transmitterwhen a bit is detected so both ends of

the chain can build up a binary word.This can be done on a non -securelink.

Because 90 per cent of informationis lost in transmission, the scheme isvirtually useless for datatransmission, but well suited tomutual generation of cryptographykeys.

QinetiQ researchers envisage aquantum key transmission linkrunning in parallel with a moreconventional laser data link.

The scheme will eventually be usedfor secure international data transferwhere information will be passed upto a satellite, then carried over toanother country and sent back down.

Technical specification.The transmitter was mounted on a30x60cm breadboard and its beamcollimated to around 50mm. At20km the received beam is 1-2m indiameter.

Pulses were transmitted at 10MHzrandomly polarised at 0, 90, 45 or135°.

The receiver worked through a30cm diameter commercial telescopeand polarising beam splitters dividedincoming photons to one of fourdetectors.

With lumped optical loss around20dB and a receiver efficiency ofaround ten per cent, the decodedinformation rate was about 1 kbit/s.

January 2003 ELECTRONICS WORLD 7

UPDATE

ASample out

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US firm makes GaN breakthroughA US firm has produced p -typegallium nitride wafers, a significantstep on the road to more commercialGaN products.

Technologies and DevicesInternational (TDI) says the 50mmwafers will result in better LEDs,laser diodes and faster high power

bipolar transistors.TDI starts with a standard 50mm

sapphire wafer and then deposits alayer of GaN using hydride vapourphase epitaxy (HYPE).

"The main advantage of GaNHYPE is a combination of highgrowth rate, up to hundreds ofmicrons per hour, and high materialquality," said Katie Tsvetkov,product manager at TDI. "Thehighest electron mobility for GaN has

been reported for material grown byHVPE."

Layers can be grown between 1 and3001.tm thick.

To produce a p -type material, thefirm dopes the GaN with magnesium,a type II element. Hole mobilityvaries between 1 and 10cm2Ns. Thebandgap remains constant at 3.39eV,Tsvetkov said. LEDs made using thematerial produce UV light at around360nm.

Les Paul goes digitalElectric guitar manufacturer Gibson has decided to add a digital output toall its future instruments. The firm has used a programmable logic devicefrom Xi linx to run its own digital transfer protocol, called MaGIC. TheMaGIC protocol allows 32 channels of 32 -bit data at 192kHz to betransmitted. The system will appear in all the firm's guitars in the next 12to 18 months. Gibson will license MaGIC free of charge to makers ofother audio equipment.

Fluids replace electricityScientists at the California Institute ofTechnology have made circuits thatuse fluids and tiny valves.

Purge input

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use fluids, the display and circuits arenon-volatile.

Dr Stephen Quake from theDepartment of Applied Physics atCaltech led the team which plumbedtogether hundreds, even thousands ofvalves and chambers using large scaleintegration techniques.

At the core of the system is whatQuake calls a fluidic multiplexor, acombinatorial array of binary valves.Just like an electronic multiplexor, 2ninputs can control 2" elements, in thiscase 20 inputs control 1,024 valves.

Valves are created by crossing`control' channels over a 'flow'channel. A thin membrane is formedbetween the channels, each around1001m wide, and this membrane canbe deflected by hydraulic pressure.Where two controls cross a flow, thepressure is high enough to close thevalve.

Chambers can also be formed withvolumes of between 250 and750picolitres.

In order to pass fluid to the chipssteel pins are inserted through a layerof silicon.

Quake reckons the chips canperform biomolecular operations suchas separations, enzymatic assays andpolymerase chain reactions.

Coloured food dies show the multiplechannels in this comparator chip.The device contains 2,056 valves and256 reaction chambers.

8 ELECTRONICS WORLD January 2003

UPDATE

a

Cars to get fast commsAutomotive communicationsrunning at 25Mbit/s over unshieldedtwisted pair wiring have beendemonstrated by a Guildford -basedfirm.

Communication & ControlElectronics (C&CE) hopes itsSmartwireX protocol will be used bycar manufacturers to add video andaudio networking, at lower cost thanfibre optic systems.

"A lot of multimedia networkinghas been led by the luxury market,"said Steve Holland, director ofprofessional services at C&CE.

The firm, originally set up byPhilips and Matsushita as a joint

Zarlink sticks withSwindonCanadian chip firm ZarlinkSemiconductor is to site its highperformance analogue design andmanufacturing group in Swindon.

The firm said the considerableexperience of the team, andSwindon's high quality fab processled to the decision. Engineers in thefirm's Plymouth site will alsocontribute to design.

The current size of the team is notbeing revealed, although the firmsaid more jobs would be created asthe group expanded.

"We will need additional people,because we have aggressive growthplans," said Peter Minett, marketingmanager for analogue products atZarlink.

Swindon will house design andmanufacturing of wireline andwireless chips, such as frequencysynthesis and timing, broadbandamplifiers and broadband linedrivers.

Zarlink recently sold its Plymouthfab to German firm X -Fab.

venture, has sold fibre optic systemsto firms such as Daimler Chryslerand Jaguar. But these systems usingprotocols such as D2B and MOSTwill prove too expensive for volumecar makers, said Holland.

"We realised that optical networksdidn't suit the environment of a massproduction car plant," he said.

However, electrical cabling cannoteasily meet the electromagneticcompatibility specificationsdemanded by an automotive system.Holland claimed that C&CE hassolved these issues, even using UTPcabling.

The 25Mbit/s network is able to

carry time critical including audioand video to various points aroundthe car

"It's going to open up cooldistributed systems to volume cars,"said Holland. Systems include DVDand CD players sending differentdata to different passengers in thecar.

Discussions with a number ofmanufacturers are ongoing, the firmsaid.

C&CE became an independentcompany in 1994 after amanagement buyout. It now hasaround 35 employees in Guildford,the majority of which are in R&D.

Swiss chips run at 0.5VA subsidiary of Swiss watch firmSwatch has developed a very lowvoltage semiconductor process thatruns down to 0.5V and attemperatures of up to 225°C.

EM Microelectronics hasdeveloped its fully depleted silicon -on -insulator (SOI) process mainlyfor its parent company, but will offerthe process on a foundry basis.

The first product to come off theline is a mixed signal IC for Swatch."The analogue portion of the circuitis operating at 0.5V, while thedigital part works even down to0.35V," said Mougahed Darwish,EM Microelectronics president.

EM said the 0.5um process issuited to a variety of products suchas RF tags, automotive, smartcards,and analogue front ends for sensors.

SOI is made by growing a thinlayer of silicon on an insulatinglayer, itself on top of the bulksubstrate.

A firm from Cambridge is proposingwireless charging of devices such as

mobile phones, handheld PCs andelectronic games. Splashpower's inductive

technology embeds a flat coil in theproduct and uses a 6mm thick plate to

contain the charging electronics. Multipledevices can be charged simultaneously,

and the pad can be embedded underglass. The firm claims charging rates are

the same as that from standard AC/DCwall plugs. In volume each pad will cost a

few pounds, the embedded coils justpence, it said.

Individual transistors can beseparated by implanting verticaloxide blocks through the thin silicon,so leakage current is much reduced.

Partially depleted SOI has beenused by microprocessor makers, anddue to the thickness of the topsilicon there is a layer of neutralcharge between the transistor andburied oxide. This suits highfrequency operation.

In fully depleted SOI, on the otherhand, the silicon layer on top of theinsulator is very thin - it needs to beless than 50nm - so the depletionregion underneath a transistor'schannel extends right down to theinsulating oxide layer.

Thus fully depleted has lowerleakage currents at reducedthreshold voltages, so is better forlow voltage and low power (but notspeed).

January 2003 ELECTRONICS WORLD 9

UPDATE

Input Y

Smallest computer uses moleculesScientists at IBM have built logicgates in which individual moleculesmove across an atomic surface in adomino -like structure.

This 'molecular cascade' is made

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from carbon monoxide molecules on acopper surface. Moving a single CO2molecule initiates a cascade of motion.

A weak repulsive force between themolecules creates a metastability, so a

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Novel UK display looking goodOxfordshire -based Printable Field Emitters (PFE) hasreleased pictures of its latest field -emission display(FED) prototype. The company claims to havejumped many of the hurdles which caused earlierFED companies to falter, saying that only wellunderstood steps are needed to get the display to astate where other companies can mass produce it.FEDs are capable of full colour operation thatmatches CRT performance in a package only a fewcentimetres thick. PFE's technology is unusual inthe FED world as it allows large displays to bemade. Big -screen TV is the target market.

Verification for IBIS modelsPCB design tool firm Zuken has setup a verification service for the IBISmodels that are often used in thesimulation of board designs.

The Tewkesbury -based firm said alack of software in the market tocreate and verify these modelsresults in very low quality models.

SiQual, the engineeringconsultancy, recently published areport and stated that 70 per cent ofall IBIS models available over theInternet were flawed.

IBIS models are created bytranslating Spice models provided bya chip's manufacturer.

By ensuring the accuracy of IBISmodels, Zuken's service aims toimprove the speed and accuracy ofPCB simulation.

Zuken will take a manufacturer'smodel data and test its precision,either against the Spice model oreven against the part itself.

"Although a few US companiesoffer an IBIS modelling service, it is

small movement in one affects itsneighbours.

The team at IBM were able toconstruct OR and AND functionsusing the technique.

Whether a set of molecules hascascaded or not is used to representones and zeros.

"The molecule cascade is not only anovel way to do computation, but it isalso the first time all of thecomponents necessary for nanoscalecomputation have been constructed,connected and then made to compute,"said Andreas Heinrich, a physicist atIBM's Almaden Research Center.

However, it's not going to result inpractical circuits any time soon. Eachcircuit has to be formed individuallyby a scanning tunnelling microscope,and can only be used once.

not widely available in Europe, andcertainly not with the accuracy of themodels that we can produce with ourexperience in this area," said WernerRissiek, the firm's manager for high-speed routeing products.

"Accurate models make a criticaldifference to the speed at whichdesigns can be verified and haveserious implications for producttime -to -market so we expect to seesignificant demand for this newservice," said Rissiek.

10 ELECTRONICS WORLD January 2003

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AIR TRAFFIC CONTROL:

Now many more air disasters?In July last year, problems with the existing systemwere highlighted by the tragic death of 71 people,including 50 school children, due to the confusion whenSwiss air traffic control noticed too late that a Russianpassenger jet and a Boeing 757 were on a collisionpath. The processing of extensive radar and otheraircraft input information for European air space is avery big challenge, requiring a reliable system to warnair traffic controllers of impending disaster. So why hasIvor Catt's computer solution for Air Traffic Control beenignored by the authorities for 13 years?Nigel Cook reports.

In Electronics World, March 1989,a contributor explained the long-term future of digital electronics.

This is a system in which computersare networked adjacently, like placesin the real world, but unlike theinternet. An adjacent processornetwork is the ingenious solutionproposed for the problem of AirTraffic Control: a grid network of

computer processors, eachautomatically backed -up, and eachonly responsible for the air space of afixed area. Figure 1 shows the newprocessing system, the Kernelcomputer, as proposed for safe,automated air traffic control.

This system is capable of reliablytracking a vast air space and couldautomatically alert human operators

whenever the slant distance betweenany two adjacent aircraft decreasedpast the safety factor. Alternatively,if the air traffic controllers were busyor asleep, it could also send anautomatic warning message directlyto the pilot of the aircraft that needsto change course.

The existing suggestions arecurrently based on softwaresolutions, which are unsatisfactory.For such a life -and -death application,there is a need for reliability throughredundancy, and a single processorsystem does not fit the bill. Systemfreezes must be eliminated inprinciple. Tracking aircraftindividually by reliably using radarand other inputs requires massiveprocessing, and a safe internationalsystem must withstand the rigours ofcontinuous use for long periods,without any software crashes orsystem overheat failure.

The only practicable way to do thisis through using Ivor Catt's adjacent -processor network.

Originally suggested for a range ofproblems, including accurateprediction of global warming andlong-range weather, the scheme

12 ELECTRONICS WORLD January 2003

AIR TRAFFIC CONTROL

proposed by Ivor was patented as theKernel Machine, an array of 1,000 x1,000 = 1,000,000 processors, eachwith its own memory and program,made using wafer -scale integrationwith 1000 silicon wafers in a 32 by32 wafer array. The data transfer ratebetween adjacent processors is 100Mb/s.

Ivor Catt's original computerdevelopment is the Catt Spiral(Wireless World, July 1981), inwhich Sir Clive Sinclair's offshootcomputer company, Anamartic,invested £16 million. Althoughrevolutionary, it came to market andwas highly praised by electronicsjournals. The technology is provenby the successful introduction in1989 of a solid-state memory calledthe Wafer Stack, based on a Cattpatent. This received the 'Product ofthe Year Award' from the U.S.journal Electronic Products, inJanuary 1990.

It is a wafer scale integrationtechnology, which self -creates aworkable computer from a singlesilicon wafer by automatically testingeach chip on the wafer, and linkingup a spiral of working chips whileby-passing defective ones. Thissystem is as big an advance as theleap from transistor to compact IC(which was invented in 1959),because the whole wafer is usedwithout having to be divided up intoindividual chips for separate testingand packaging.

By having the whole thing on asingle silicon wafer, the time andenergy in separating, testing, andpackaging the chips was saved, aswell as the need to mount themseparately on circuit boards. By thetime Catt had completed hisinvention for wafer scale integration,he was already working on the more

advanced project, the KernelMachine.

In the Sunday Times (12 March1989, p. D14), journalist Jane Birdinterviewed Ivor Catt and describedthe exciting possibilities: "in airtraffic control, each processor in thearray could correspond to a squaremile of airspace... weather -forecasters could see at the press of abutton whether rain from the westwould hit Lord's before the end ofcricket play."

The Kernel machine versusP.C. thinkingThe primary problem facing theKernel Machine is the predominanceof single -processor computersolutions and the natural inclinationof programmers to force softwarefixes on to inappropriate hardware.

Ivor Catt has no sympathy withideas to use his Kernel Machine forchemistry or biology research.However, this sort of technology isvital for simulation of all real -lifesystems, since they are all distributedin space and time. Chemicalmolecule simulation for medicalresearch would become a practicalalternative to brewing up compoundsin the lab, if such computers becameavailable. It would help to find bettertreatments for cancer.

Modern research on the brainshows that the neurons areinterconnected locally. Quite oftenthe false notion is spread that theneocortex of the brain is a type ofInternet'. In reality, the billions ofneutrons are each only connected toabout 11,000 others, locally. Thenetwork does not connect each cell toevery other cell. This allows it torepresent the real world by a digitalanalogue of reality, permittinginterpretation of visual and other

sensory information. Each processorof the Kernel Machine is responsiblefor digitally representing orsimulating the events in a designatedarea of real space. Certainly, theKernel machine would be ideallysuited to properly interpret streamedvideo from a camera, permittingcomputers to 'see' properly. Thiswould have obvious benefits forsecurity cameras, satellite spy andweather video, etc.

Catt filed patents for the KernelMachine in Europe (0 366 702 B I,granted 19 Jan 1994) and the U.S. (5055 774, granted 8 Oct 1991), a totalpatenting cost around the world ofabout £10,000. His earlier invention,the Catt Spiral, was patented in 1972but only came to market 17 yearslater after £16 million of investmentby Anamartic Plc.

Patented design for the newkernel computerFigure 2 shows how the Kernelpatent differs from the Spiral in twoimportant ways. The Spiral design asutilised in the Anamartic memorywafer, once it has been manufacturedlike an ordinary silicon wafer, is setup as a whole wafer computer bysending test data into a chip on theedge of the wafer.

If that chip works, it sends test datainto another adjacent chip, which inturn repeats the process: side-stepping faulty chips andautomatically linking up the goodchips into a series network. Eachchip that works is thereforeincorporated into a 'Spiral' ofworking chips, while each defectivechip is bypassed. The result saves thelabour of dividing up the wafer,packaging the individual chipsseparately, and soldering themseparately on to circuit boards. It

How an adjacent -connection network of processors would manage ATC of European air space

RADAR INPUT DATA FOR ATC IS VERY COMPLEX ADJACENT NETWORK OF PROCESSORS (ARRAY)

Figure: 1.

January 2003 ELECTRONICS WORLD 13

AIR TRAFFIC CONTROL

Figure: 2.

SERIES CONNECTION(Chips are tested, then

defects are side-steppedto give a good chip "spiral")

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"Kernels" for networkinglinks through the bad chips)

saves space, time, and money.The problem with the Catt Spiral is

that by creating a spiral or seriesconnected memory, it causes timedelays in sending and receiving datafrom chips near the end of the spiral.Data can also be bottlenecked in thespiral. The invention was innovative,and won awards; yet by the time SirClive Sinclair was ready to beginproduction for a massive wafer scaleplug-in memory for computers, IvorCatt was already arguing that it wassuperseded by his later invention, theKernel machine. Born in 1935,Cambridge educated Catt isextremely progressive. Hisimmediate replacement of earlierpatents of his own when newdevelopments arrive seems logical tohim, although it can disturb thosewho invested in the previous designwhich has yet to make a profit.

The adjacent linking of chips into atwo dimensional array in the KernelMachine, is so -named from the`kernels' in the corners of each chipwhich allow networking through thechip even if it has errors and is notused itself. Kernel computers aredesigned to have enough networkingto avoid all of the problems of theSpiral wafer. Kernel's built-in 'self -repair' works by ignoring individualchips when they burn out, theconcept of reliability throughredundancy. There are sufficientspare chips available on each waferto take over from failures.

Catt's intended scientific andcommercial computing companycalls for a three -stage investment of£0.5m, £8m, and £12m, respectively.The project outline states: "Thescientific market and the commercialmarket need to be aware that thereare two fundamentally differentmethods of computing: large, singleprocessing engines performing singletasks one at a time, and parallelsystems where there is an array ofsmaller engines that perform a seriesof tasks independently of each otheruntil they are brought together bysome management mechanism togive a result. The scientific market'smajor application areas are: scientificand engineering computing; signaland image processing and artificialintelligence.

"In the commercial world there area number of application areas wherethe application of very fast numericalprocessing is extremely useful. Asthe limits of physical performanceare now in sight for semiconductors,the next level of performance will beachieved by applying an array ofprocessors to a particular task. Toachieve even betterprice/performance ratios than ispresently available, the architecture

needs to be flexible enough to useany one of a number of computerprocessor types.

"Having proven the technology andits ability to be applied to specificoperational areas, the company willset to licence the technology withinthese application areas. The companywill also develop intermediate andperipheral products on its route to themajor goal; that of a parallel -processing super -computer usingpatented technology.

"In common with all companiesfirst entering a high technologymarket, this company will make aloss during the initial stages. Thevarious stages of productdevelopment will be interposed withthe marketing of that development. Itis anticipated that this will reduce thenegative cash flow impact inherent inan R&D environment. Industrynorms have been applied to the costof sales, marketing andadministration expenditures, and tothe capital costs."

In order to develop the software forthe Kernel Computer, currentcomputer technology will be used,networked in the Kernel adjacentprocessor array. Software, for all ofthe challenges facing the KernelComputer, can be tested anddebugged on this inexpensive mock-up. The next phase will be theproduction of the first large scalesuper -computers using the Kernelsystem of wafer -scale integration.

Catt comments: "The first WaferScale Integration (WSI) product, asolid state disc called Wafer Stack,came to market in 1989, based on`Cat Spiral'. We can now advance toa WSI array processor, the Kernelmachine, with one million processorsgiving one million million operationsper second. The Kernel machine,when built from an array of 100wafers, will retail for £500,000. Theexternal control system maps out thegood and bad chips, and devises astrategy for building a volatile,perfect square two-dimensional arrayof 1,000,000 processing elements(PE's) out of a larger, imperfectarray. Reliability is achieved throughredundancy; having spare PEsavailable.

"The project costs £20 millionspread over four years. A properfigure for profit in this market wouldbe 20% of retail price. The $0.2Bnturnover needed to justify the Kernelproject is dwarfed by the $50Bnworld computer market." The Kernelarray computer is the machine of thefuture, replacing the single processorvon Neumann machine of the presentday.

14 ELECTRONICS WORLD January 2003 at

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COLOUR CCD CAMERAS.."

Undoubtedly a miracle of modern technology &our special buying power I A quality product fea-turing a fully cased COLOUR CCD camera at agive away price ! Unit features full autolight sensing for

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SOFTWARE SPECIALSNT4 WorkStation, complete with service pack 3and licence - OEM packaged. ONLY £89.00 (ts)ENCARTA 95 - CDROM, Not the latest - but at this price ! £7.95DOS 5.0 on 3fi" disks with concise books c/w QBasic . £14.95Windows for Workgroups 3.11+ Dos 6.22 on 3.5" disks £55.00Windows 95 CDROM Only - No Licence - £19.95Wordperfect 6 for DOS supplied on 3fi" disks with manual £24.95

shipping charges for software is code B

SOLID STATE LASERSVisible red, 670nm laser diode assembly. Unit runs from 5 V DC atapprox 50 mA. Originally made for continuous use in industrial bar-code scanners, the laser is mounted in a removable solid aluminiumblock, which functions as a heatsink and rigid optical mount. Dims ofblock are 50 w x 50 d x 15 h mm. Integral features include over tem-perature shutdown, current control, laser OK ouput, and gated TTLON / OFF. Many uses for experimental optics, comms & lightshowsetc. Supplied complete with data sheet.

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All prices for UK Mainland. UK customers add 17.5% VAT to TOTAL order amount. Minimum order £10. Bona Fide account orders accepted from Government, Schools,Universities and Local Authorities - minimum account order £100. Cheques over £100 are subject to 7 working days clearance. Carriage charges (A)=£3.50, (B)=£6.50, (C)=£10,

Esr. (D)=£15.00, (E)=£18.00, (F) CALL. Allow approx 3 days for shipping - faster CALL. All goods supplied to our Standard Conditions of Sale which can be viewed at our website andunless stated guaranteed for 90 days. All guarantees on a return to base basis. All rights reserved to change prices / specifications without prior notice.Orders subject to stock.

Years Discounts for volume. Top CASH prices pad for surplus goods. All trademarks, tradenames etc acknowledged. © Display Electronics 2002. E & 0 E..

15

EXHIBITION REVIEW

The Taiwan electronics industry has long beeninternationally famous for its manufacturing ability.However, as the environment changes, Taiwanmanufacturers must transform and upgrade themselvesto survive severe competition. As a consequence,production lines are being expanded to lower cost placesfor longer -term development. Charles Ward to reportson developments at the recent Taitronics exhibition.

TAITRONICS TAIWANTaiwan manufacturers are graduallyswitching the production of low-levelproducts to overseas, while Taiwanserves as the base for developing and

producing high-level products as well asmarketing. With effort, Taiwanmanufacturers will eventually be able totransform themselves from a manufacturingcentre to an international supply centre ofinformation, communication and consumerelectronics products.

The ultimate goal is to make Taiwan theglobal electronics management centre, andthe growing pattern of procurement inTaiwan and offshore distribution indicatesthat Taiwan - or "Silicon Island" as it likes tobe called - is slowly achieving that goal.There is reason for firm conviction - well,there has to be - that with the advantages of

superior flexibility and efficiency, Taiwan'selectronics industry will continue isgrowth.Taiwan has over 40 years experiencein consumer electronics manufacturing andin 2001 its exports of these products werevalued at US$3.75 billion. Many Taiwanesecompanies have formed alliances with well-known foreign companies to bolster theirmarket strength at home and around Asia.Following the entry of both mainland Chinaand Taiwan into the World TradeOrganisation in November 2001, the area'smarket potential is bound to bring vastopportunities.

TVTaiwan may not be well known for itsinventiveness of colour television receivers,particularly as there are only seven CTV

manufacturers on the island, but things arechanging. At the autumn Taitronicsexhibition organised by The China ExternalTrade Development Council (CETRA) andthe Taiwan Electrical and ElectronicManufacturers' Association (TEEMA) heldin Taipei, Taiwan's second biggest CTVmanufacturer - Kolin - introduced a rearprojection digital CTV that the companyclaims to be only the second of its type to beannounced in the world.

Known as LCOS (Liquid Crystal onSilicon), this new technology significantlyaccentuates the colour on screen providing abrightness of 775 nits. Utilising threereflective light imagers and a sophisticatedprism and lens system, light is transformedinto a laser -like beam and imprinted with ahigh -definition image that is then magnified

16 ELECTRONICS WORLD January 2003 116

EXHIBITION REVIEW

1

and displayed in a perfectly alignedwidescreen format. For the past three to fouryears Kolin has focused its development onplasma TVs, but in the past 18 months thecompany has diverted its effort into theLCOS receivers.

Jeff Tsai, assistant vice-president of theinvestment management centre at the KolinGroup told Electronics World that the newreceivers "would be around 40% lower inprice than plasma and power consumption ofLCOS was considerably lower than plasma".There is also around a 60% saving in weightcompared with a conventional rear projectionCTV. Mr Tsai added: "Plasma's limitationsof short lifespan and ability to be repairedeasily could see the system downgrade intwo or three years with LCOS and its superbpicture quality and longer lifespan, takingover."

The model on show by Kolin was a 50in16:9 version with a front -to -back cabinetdepth of 43cm Kolin hopes to reduce that to35cm very soon. This new flicker free CTVhas a high contrast and crisper picture that isimmediately different to the eye from otherTVs.

Apparently RCA has recently debuted aLCOS CTV in America and Toshiba andwith its strength in rear projection CTVs, issaid to be the most aggressive of theJapanese makers researching LCOS. InEurope, Philips is believed to have aprototype.

Remote controlsA number of companies at the Taitronicsexhibition were introducing touch screenremote controls. Typical of these is a modelfrom Sunwave that will mimic up to 16remote controls and is ideally suitable forcontrolling home theatre systems.

DVDAmongst a host of DVD players exhibited bya number of manufacturers was the Abossultra slim, combined player/amplifier fromSliMax International. This young company -only six years old - has combined the servoand decoder functions into one IC. The DVDplayer will work on all power sources andTVs - Europe, Japan, US, etc, with norequirement for voltage or video converter.

The player also includes a digital photoplayback system that allows the user to easilynavigate among digital pictures on a TVscreen. The built-in amplifier provides sevenreverberative sound modes - concert/livingroom/hall/bathroom/cave/arena/church andseven preset audio EQ mode option(rock/pop/live/dance/techno/classic/soft).

KitsMechanical motorised kits have taken on anew meaning at Taiwan manufacturer CIC

Components with the launch of a solar -powered range of kits. In designs that includedinosaurs, helicopters, skeletons, steamtrains, robots and racing cars, these kits aresupplied as wooden constructions withpulleys, gears, shafts, switches and motor.All the young 'engineer' requires toconstruct the kits are a knife, screwdriver andlong nose pliers.

Also from CIC is a range of electroniceducation kits that includes a line trackingmouse and a robot car that reverses when itsenses noise or touches obstacles. Kitsinclude a motor, two sets of gears, metalshafts, gearbox and various other accessories.

TelecommunicationsTaiwan's communications industry reachedUS$2.69billion in 2001, but like most of theworld the telecommunications industry inTaiwan has been hit recently by theworldwide slump in sales of mobiletelephones, etc. Severe competition fromChinese manufacturers has also put pressureon Taiwanese companies.

Local manufacturers blamed over-optimism of major international mobilephone brands for the lower than expectedmarket performance, which resulted intremendous stocks of finished products aswell as components.

Main introductions at the exhibition weremobiles with the ability to control as many as10 different telephone numbers on one SIMcard; mobiles with coloured screens werepopular innovations; hands free mobilesystems; and Bluetooth headsets.

EmailCreating an email takes on a new meaningwith the introduction of the PenSuite 3Ddrawing tablet with cordless pen and wirelessmouse.

Kolin 50in 16:9 LCOS television

Contacts

Kolin: www.kolin.com.tw

Slimax: www.slimax.com.tw

CIC Components: www.cic-components.com

Sunwave: www.sun-wave.com

UC-Logic: www.UC-Logic.com

Taiwan First Line Electronics:www.bafo.com.tw

Available from UC-Logic Technology, theprogram allows the user to hand writeemails, sign emails or even draw and sketchon emails.

Drum kitOne thing in common with most Far Easterncompanies is their ability to create aggressivelow pricing for products.

One such case is an electronic drum systemby Taiwan First Line Electronics. Thecompany has introduced a drum kit thatincludes five percussion pads, a kick treadle,an instruction CD, and 110 combinations ofbacking sound.

Similar drum kits by top name companiescost around £750 each whereas theTaiwanese company suggests a retail price of£220.

January 2003 ELECTRONICS WORLD 17

INSTRUMENTATION

Modern impedancemeasurement techniques IIIn his second in-depth article investigating modern methods of measuringimpedance, Alan Bate* first rounds off his explanation of circuit blocks used inmodern LCR measuring instruments. He then discusses how measurements aremade and how the frequency range of instruments can be extended.

*Alan Bate BEng(Hon's) MIEE

In my previous article, I mentioned that the phase -sensitive detector, PSD, used in impedance measuringinstruments is an analogue multiplier. Consequently,

any harmonics in the PSD reference make the circuitsusceptible to any harmonics of the same frequency in thestimulus.

A simple square -wave driven PSD is the most vulnerableto odd -harmonic distortion. This is because the referencecontains an infinite range of odd harmonics. Ideally, thegoal is a very pure, stepped sine wave reference havingminimal harmonics and the simplest possible synthesismethod.

By generating an approximate, or quasi, stepped sinewave, where each step level is matched to the integral ofthe sine for that time sample, the four -level -by -eight time -sample waveform has no harmonics below the seventh asdiscussed last month.

Only two switches are needed for this circuit. This is amajor consideration, as each analogue switch willcontribute charge injection into the PSD output.

Integration of the PSD current output will convert theinjected charge into a DC offset, which growsproportionally with frequency. While this offset can becompensated for in the offset readings, the dynamic rangeis reduced as the offset shifts the phase detector'sanalogue -to -digital converter bias point. This effectivelyreduces the instrument's dynamic range.

In practice, the drive level may have to be reduced at thehighest frequency settings to avoid slew rate distortion inthe rest of the measuring chain.

Current output from the PSD is fed directly into theA -to -D converter's virtual earth. This avoids anunnecessary transimpedance stage, which would attemptto generate the fast voltage edges with consequent slewrate distortion.

By merging the detector and A -to -D converter, the PSDoutput waveform is integrated by the converter, avoidingthe potential slew rate problem.

A -to -D conversionThe simplest approach to analogue -to -digital conversion isthe dual -slope technique, as used in low-cost digital multi -meters for many years, Fig. 1.

Dual -slope converters have an integrator that samplesthe signal for a fixed integration period. This is usuallymade a multiple of the supply frequency in order to rejectsupply -related noise: the same principle is applied in theLCR instrument to reject PSD ripple.

Output from the integrator ramps linearly until the signalis turned off at the end of the fixed integration period. Thisalso prevents overloading. Now, the integrator is reset byswitching a reference current into the integrator input,causing the output to ramp back to zero.

During the ramp down, a counter is enabled allowing acount from a high frequency clock to accumulate. Whenthe output ramp passes through zero, a zero -crossingcomparator is set which stops the measurement counterand resets the integrator.

Because a ratio measurement is made between theintegrate and de -integrate timings, all the tolerances in theintegrator circuit are cancelled.

In an LCR instrument though, there's a very wide signalrange, with the rapid succession of large followed by tinymeasurements. It has been found that dual -slope A -to -Dconverters suffer from non -linearity due to;

Dielectric distortion in the integrator capacitor. Ramp non -linearity at high signal levels due to the

onset of amplifier slew rate distortion as the rampapproached the amplifier maximum output level.

Dielectric storage became noticeable because theinstrument's dissipation factor degraded while measuringsmall capacitors with very low dissipation factor - smallpolystyrene capacitors for example. Here the tiny currentreading would immediately follow a large voltage reading.The residual charge in the integrator capacitor would nothave been removed during the A -to -D converter's resetperiod but became added to the following measurements.

The limited dynamic range of the integrator at near fulloutput also affected the amount of tolerable PSD ripple,Fig. 2, possibly overloading the integrator output with largePSD ripple. As a result, dual -slope A -to -D converters areonly used on low-cost LCR instruments.

Quantised feedback conversionTo overcome the limitations of dual -slope conversion,`quantised feedback' or 'charge balancing' conversion isused. This method has none of the above limitations andsome additional advantages.

In this approach, dielectric storage is simply avoided bynever allowing the integrator capacitor voltage to develop.This also avoids slew -rate non -linearity of the integratorby maintaining small -signal amplifier operation.

In addition, because the amplifier output voltage range isnever used, a theoretically infinite integration period couldbe applied in a microprocessor controlled system. Thisallows long integration periods to be used for enhancednoise suppression. In practice, very long integrationperiods are limited by the 1/f noise of the integratoramplifier and reference circuits.

Integrator output is regulated by a simple PWM controlloop, which corrects the integrator output voltage byinjecting a reference current or charge, Fig. 3, to return theoutput to zero.

The high/low comparator compares the output to OV andsets the reference current accordingly. The on/off current

18 ELECTRONICS WORLD January 2003

a INSTRUMENTATION

a

a

egg

a

a

I

Input

ANALOGUESNATCH

Reference

Ov

-v

START

is

Integrator

Reset

00C.,

fl1

INTEGRATOR

Fig. 1 Basic dual -slope A -to -Dconverter andassociatedwaveforms.

waveforms are designed to have equal and oppositenumber of switching transitions to cancel switching chargeinjection at the integrator input, Fig. 4.

In order to reject the large amount of AC ripple from thePSD output, the integrator is synchronised to integrateover a whole number of stimulus cycles as mentionedearlier. At the end of the integrate period the PSD is turnedoff but the reference current is left full on. See Fig. 3,charge -balance waveforms.

Now, the integrator ramps to an arbitrary end of rampcomparator threshold. The comparator trips, setting theend of the measurement sequence. The comparatorincludes hysteresis to lock out possible multiple transitionsdue to the slow ramp rate and noise.

The measurement is accumulated in a measurementcounter that's enabled each time the integrator output isreset, or reference current applied. This includes the finalramp down to the end -of -ramp comparator threshold.Residual bits of the conversion are resolved by this finalramp.

As in the dual -slope method, the signal is integrated for afixed period, but there is no waiting for the end of theintegration period before applying the DC reference.Instead, the DC reference is summed with the input signalduring the integration period.

Summing the DC offset with the signal avoids a separateDC offset measurement, enabling the conversion rate to beincreased significantly compared to dual -slope conversion.On a large signal, the dual slope also takes longer to de -integrate. The integration period would be the same ineach case.

The hardware measurement counter can be smaller thanthe full 22 -bit resolution would imply by simply recordingthe number of counter overflows in the software. Thecharge -balance current must balance the maximum input

AnalogueSwitch

COMPARATOR

DATA READY

Latch

> E

CLOCK

Input voltage

Integrate period

N bit Modulo counter

Reference voltage

Zero crossingcomparator trips

Start

IrSD ripple over toadsIntegrator duo to amplifierseed MOM IIMit

Low frequency PSD icpk

Or

Start edge

Data ready

Integrate period

Fig. 2. The integrator's limited, dynamic range at near full output

affects the amount of ripple in the\ detector (repeated from last

month's article).

Zero crossing comparatorfires

Is.P edge)

January 2003 ELECTRONICS WORLD 19

INSTRUMENTATION

Start Measurementcommand from uP

MSR

1

PSD Drive

PSD Drive 2

CBC

STOP

Latch

Charge Balance Signet.

Integrator output

Fig. 3. Waveforms involved in the PWMcontrol -loop regulation technique ofquantised feedback A -to -D conversion, top,and basic elements of the converter, below.

Input

Start

Integrateswitch

Vreference

V Offset current

During final ramp period the PSD isturned off. Reference current forcesIntegrator to ramp until end of rampcomparitor threshold is reached.Compwitor trips and measurementstops.

CBC Switch

Run

Integrate

(N)

End of MeasurermentSet by End of ramp comp ant°,

Synchronise to measure signal

RUN latch

Run measurement

Integrate period set toe muffin!enumber of measure cyclesby the harriers.

Nominal Integrate period setby uP

PSD Drive I

PSD switches driven by PSDI USD 2 generatequasi stepped sin reference waveform.

PSD Drive 2

High /Low competitorcompares integrator output toground and sets CBC signalto correct integrator.

F-Charge Balance Signal.

Measure count is enabledeach time balance current Isapplied.

Integrator output

End of ramp threshold

End of ramp compantortrips and resets RUN latch.

-Vref

Charge BalanceControl

High/Low

LILJTIS

End of Ramp

CBC Generator

RunIntegrate

Integrate Timer

Run

20 ELECTRONICS WORLD January 2003 11.

INSTRUMENTATION

si

current. This means that the notches in the two chargebalance waveforms have the effect of reducing thetheoretical dynamic range by the ratio of the notch timedivided by the charge -balance conversion period at eachend.

Frequency of the charge balance signal has to be chosenwith care to avoid beats with the PSD ripple. Low -frequency signal ripple tends to be chopped by the chargebalancing process, preventing ripple build up.

Increasing the ripple frequency improves the chargebalancing and PSD ripple rejection. But it also increasesthe charge injection from the charge balance switching.Increasing the charge injection adds an unwanted offsetalong with the charge injected by the PSD switches.

INTEGRATOR 0/P

INTEGRATE

REFERENCE

INTEGRATOR 0/P

INTEGRATE

REFERENCE

DUAL SLOPE )

[ CHARGE BALANCE I

This diagramclarifies whythere is a speedimprovement

I_ with chargebalance A -to -Dconversion over

1-c-dual slope.

Conversion time reduced

Overall, the charge balancing A -to -D converter givesexcellent performance. With very long integration periods,the circuit is limited by low -frequency 1/f noise from theband -gap reference and integrator amplifier. Theimpedance range of the instrument is therefore reduced tomaintain a practicable number of precision range settings.

RangingLike all signal -processing systems, we are limited indynamic range. At maximum drive signal, overloading thedetector must be avoided. If this occurred in a basic LCRinstrument, where auto ranging is totally based on theimpedance reading, the measurement process would go ourof control.

Without a measurement, the software would have noreliable means of sensing which way to go in auto rangingor optimising the signal levels for best resolution.Consequently, the instrument must have a hardware rangesetting, that's 'bomb proof' and cannot overload in orderto recover from any abnormal auto ranging situation. Thisis normally a lower mid range where the drive source iscurrent limited with a swamp resistor to prevent overloadinto a short circuit.

Drive voltage and range gain settings are set to avoiddetector overload with an open or short circuit. Normally,from the drive level set by the user, the firmware carriesout an auto -range process by making a fast initialmeasurement and then testing for an impedance readingwhich is ±5% beyond the nominal impedance range upperor lower range limits. This prevents hunting at the rangeboundaries.

On lower impedance ranges, the drive signal must be setto current drive by selecting the swamp resistor. On higherimpedance ranges, the swamp resistor is switched out togive voltage drive.

T/8

CMOS MUX switches

EialEs signals

RI

1/10

1/100

R2

P3

04

Reference current on

Fig. 4. The charge -balance waveforms aredesigned to have an equal and oppositenumber of switch transitions in order tobalance out charge injection from switchself capacitance.

Reference current off

V

R5

SWI

SW2

SW3

uP control

(Fixed gain stage)

R7

R6

C1

Where the hardware changes in drive level or drivemode, (voltage or current), the user is informed via thedisplay. While this approach makes for a 'user friendly'instrument, it can be unsatisfactory when makingmeasurements of voltage -controlled impedances such asvaricap diodes and high -permittivity ceramic capacitors.For this reason, some LCR instruments allow the user tohave voltage drive for any impedance that is within thedrive output power capability. For this functionality,additional firmware is required to detect for anyoverloading of the stimulus, Eu or E, signals. These are theunknown and standard voltages discussed in last month'sarticle.

With the wide range of operation required in impedancemeasurement, the typical LCR instrument will have atleast seven range settings to cover a impedance range oftypically 0.152 to 10MQ, depending on the acceptabledynamic range of the detector.

Typically, the detector would be expected to work downto 1/10 of full range, giving 100:1 in impedance range foreach combination of voltage and current range setting.With a high frequency high-speed precision bridge thedetector range might be reduced to 1/1/10 of full scale toaccommodate;

Tighter error budget Additional non -linearity contribution from the

frequency down conversion mixer. More on this in nextsection.

Higher noise due to the conversion loss from the mixer. Shorter PSD/A-to-D integrate times with consequent

higher PSD/A-to-D noise.

For the same measurement/accuracy conditions, this wouldrequire ten times as many fixed ranges for the sameimpedance coverage! The instrument range of impedanceis therefore reduced to maintain a practical number ofprecision range settings.

The precision gain ranging is achieved by using wide

To detector

Fig. 5. Method ofranging usingfixed gain and aprecisionattenuator.

January 2003 ELECTRONICS WORLD 21

INSTRUMENTATION

Fig. 6 Instrumenterror can be

described as a bowlshaped

three-dimensionalsurface. Here it is

expressed as acontour map on atwo dimensional

piece of paper withimpedance on the Y

axis, frequency onthe X axis and totalpercentage error inthe Z axis. Courtesy

Wayne KerrInstruments.

1000H

100H

10H

1H

100mH

10mH

1mH

100pH

10pH

1pH

0.1pH

band resistive attenuators and keeping the range amplifiergain constant, Fig. 5.

Amplifier gain is fixed at the level required for thelowest expected signal for full accuracy. The attenuator isset to minimum attenuation, giving maximum range gain.As the signal is increased, the firmware sets the attenuatorto increasingly higher attenuation settings. This methodgives consistent bandwidth, as the amplifier gain is notaltered.

If the ranging was set by changing the amplifierfeedback, the gain could not be set to sufficient accuracyand the phase would change at each setting due to thefinite amplifier gain bandwidth. For this reason, thisapproach is also used in wide -band instruments such asoscilloscopes so that the waveform does not change withthe vertical sensitivity setting. (This did happen with someolder valve scopes).

While the signal is attenuated before the amplifier,which seems a bad idea noise wise, remember that this isonly as the signal is increased. At the lowest level where

11111b11111%

11110.111t5z4111111111111 II II231111111111111.1111Mil

Vac250mV or Iac=1040mA

11111111111%

1111111111111111 111111111111111

111'.IIIIIIHgh Level Accuracy EMI!111111111111.1111.11111111.11.111111

11111111111111111111111111 1111111111111111111HUMINION 11M1111111111111111111111M111111111111M111111

111101110M111111.1111111111IIMMIIIIIIM1111111am 111111111111101111M.

At and above. accuracies holdfor levels 25mA - l010mAUP to 40klis the low inductance limit for eachaccuracy range increases 2.5 times at 25mA level.

EGERMILI IL NEB

110011 1111111

1 I

100 1k 10k 100k Frequency (Hz)

the instrument noise performance is most important thevoltage attenuation is zero.

The additional resistors at the potentiometer settingsensure constant source impedance is seen by the analogueswitch capacitance and hence consistent time constant ismaintained.

Calculation and displayThe analogue -to -digital conversion results are formatted as22 -bit fixed-point numbers. Six readings are taken for anormal measurement, consisting of the real (1) andquadrature (Q) components of Eu and Es.

In addition, DC measurements are made for and Es.

with the drive signal turned off. This gives the preciselevel of the DC offset inserted to bias thePSD/A-to-D-converter combination to mid range to enablebipolar operation.

Once the offset corrected values of a, b, c, & d areobtained, the impedance can be derived using only four -function maths (see equation below.)

For high accuracy, hence slow measurement, the DCdrift between each in -phase and quadrature measurementis offset corrected, requiring another two dcmeasurements, giving eight readings. In the following,only normal to fast measurements are considered.

With unknown voltage Eu=a +jb and current shuntvoltage Es=c+jd' and,

411110101M= x nstandard

=Ra+jbc + jd

hence:

R (ac + bd)+ j(bc + ad)= c2 +d2

First, the trim corrections are applied. For low impedances,typically below a 10000 range boundary, the series realand reactive terms are subtracted.

Parallel (open -circuit trim) values are converted toadmittance and subtracted from the unknown admittance.Having removed the DC offsets in fixed-point maths forspeed; the data is now converted to floating point numbers.

Omega is re -calculated and stored whenever a newfrequency is selected.

Considering low impedances, the series resistance R, iscalculated. Using complex -number algebra:

Zj = {(ac -bd2)+ j(bc - ad )Ic2 + d2

x range number

The in -phase series term,

R =ac - bd2

x range number'

c2 +d2

Series reactance term

X - be-adc2

x range number

The range number is a scalar value. It takes account of anygain and standard resistor value selected in the hardware tocover that particular impedance range. The series trimvalues are then subtracted and the appropriate readoutvalue calculated according to the auto range or user'sdisplay mode selection

For example, with a low impedance range selected, thebridge auto -ranging firmware would choose seriesimpedance mode and select according to the sign of thereactance term either;

I22 ELECTRONICS WORLD January 2003 a

INSTRUMENTATION

OM

JO

Fig. 8. Photo a) shows a Wayne Kerr four -terminal fixture,b) shows tweezers for measuring chip components using atwo terminal connection method and c) shows Kelvin clips,again from Wayne Kerr.

R = R,

and,

L=L =X

Or,

1C =(Os

Dissipation factor is given by,R,D = -Xs

and quality factor by,

=RS

With a high impedance range selected, the auto rangingwould choose parallel impedance mode and again selectaccording to the sign of the reactance term;

Rp = Rs(1 + Q2) ohms

and,

Lp = L,(1+ D2) henries

or,

Cp = f'D, farads

Or,

1

Q2)Gp =

R,(,1+

siemens

If selected by the user, polar form would be displayedfrom;

Z = +X;

or angle,

= arctanX

R,

Specifying LCR instrument accuracySpecifying an impedance meter is a little involved, asimpedance is three dimensional. It has a real part, areactive part and a frequency. In addition, the bridge isprimarily limited by the guard amplifier shunt load

Fig. 7. Four -terminalmeasurementconfiguration usingscreened leads.

performance with frequency and amplifier noise.At the extremities of the range of impedance magnitude,

the bridge is either noise limited on the voltage signal Eisfor very low impedances or the current shunt Es signal forvery high impedances. At very low frequencies, 1/f noiseand drift come in to play. At high frequencies, the highimpedance range required by the user falls, which offsetsthe Es noise limitation.

However, distortion in the entire signal processing stagesincreases, hence the instrument error can be described as abowl shaped three-dimensional surface. For a givenstimulus level, this error bowl is best expressed as acontour map on a two dimensional piece of paper withimpedance on the Y axis, frequency on the X axis and totalpercentage error in the Z axis, Fig. 6.

Adding DC resistance measurementSo far, I have only discussed AC impedancemeasurements. Resistance at DC can also be measured

di January 2003 ELECTRONICS WORLD 23

INSTRUMENTATION

Fig. 9. Differentialmixer system

used by WayneKerr.

[ Normal Eu/Es switch

+ye senseinputs

-ve senseinputs Unity gain

buffers toisolate lowimpedancesused in mixerstage

Current steering FET switchesused in chopper mixer

Image frequency trapfilters

with good resolution and range by simply changing to aDC stimulus and chopping the Eu and Es signals prior topassing to the ac coupled ranging and detector circuits.

Frequency of the chopper is arbitrary, but it isadvantageous to choose a multiple of the instrumentssupply frequency in order to integrate out supply noise atthe A -to -D converter. A good choice is 300Hz because it isa multiple of both 50 and 60 Hz supply frequencieswithout switching excessively fast and introducingunnecessary chopper noise.

The chopped signals enable normal AC measurement tobe used. The DC stimulus level is usually kept small, ataround 100mV, in order to minimise the risk of saturatingsmall magnetic components. This extends the usefulness ofthe instrument in measuring sensitive tape heads.Measurement accuracies of 0.5% from 0.2Q to 5kQ with aresolution of 0.2mQ is typical.

Transformer turns ratioTransformer turns ratio measurement can also be includedin the suite of measurements by simply connecting theprimary in the drive path, between the E and / terminals.The primary and secondary voltage ratio are measured viathe sense leads.

Typical accuracy would be 0.1% up to around 100:1ratio. The sense leads are normally connected to the driveleads via limiting resistors, just as in power supplies, sothat a missing sense connection defaults to two terminaloperation and control is not lost.

For transformer measurements, these components mustbe switched out in order to monitor the transformersecondary unhindered. The firmware has to check theprimary impedance for resonance to avoid possibleoverloading before making a measurement.

Connections for accurate measurementsImpedance measurement covers an infinite range fromshort circuit to open circuit and zero to infinite frequency.Good bridge design therefore will attempt to offer as widea measurement range as possible, consistent withinstrument cost.

The optimum method of measurement varies over theimpedance range. As a result, different considerations haveto be given regarding the type of component, impedanceand parameter to be measured.

The most troublesome area for high accuracymeasurements is low impedance components, below say

Square wave localoscillator drive

Low pass filterTo Range Amp

10052. Here the voltage drops down the measurement driveleads become increasingly significant as short circuit isapproached.

To avoid this, the four -terminal or Kelvin connectiontakes voltage sense connections directly across theunknown impedance, Fig. 7. Assuming a high inputimpedance sense amplifier, the effect of the drive leadresistance can be eliminated using this method.

All four leads should be screened for electrostaticshielding. In addition, the drive leads should be coaxiallylinked by maintaining a return path back through thecoaxial screens to maintain electromagnetic shielding.

A second problem with low -impedance measurement isthat increasing drive current creates mutual coupling of thedrive signal to the sense connections. Ideally the drivecircuit should be floating from the instrument ground and acoaxial signal maintained for the drive circuit from Eterminal, through the unknown to the I terminal. Thisavoids a possible loop current and consequent coupling tothe sense leads.

This facility was made available on an early GenRadbridge by using an isolating output transformer at the driveterminal. This is not practical with a wide frequency rangeinstrument, or for ease of use. Therefore, a compromise ismade, namely the measurement port grounds are linked atthe instrument's front panel.

For accurate low impedance measurements, the driveleads should be twisted and the coaxial screens linked atthe unknown end for minimal loop area. From the higheraudio frequency range, the drive leads can be wound on ahigh -permeability tape -wound toroidal core to form acommon -mode transformer. This tends to force the drivecurrent to flow only in the drive coaxial screens and notthe instrument ground, giving the same effect as anisolated stimulus.

Again, for accurate low impedance measurement thephysical positioning of all the measure leads must be keptconstant so that any mutual couplings are constant and theshort circuit trim will remain valid.

Test fixtures have been developed to meet the four -terminal requirement for leaded and surface -mountcomponents. For leaded components, Wayne Kerrdeveloped a fixture that used curved Beryllium copperfingers in the mid eighties. It had a pressed out ridge oneach finger to contact and hold an axial or radialcomponent.

The component is inserted between the fingers that are

24 ELECTRONICS WORLD January 2003

INSTRUMENTATION

housed in a plastic jaw and the whole jaw assembly slideson a support bar with sliding contacts. The two jaws areslid to adapt to the component lead spacing with axialcomponent inserted horizontally and radial componentsvertically, Fig. 8a).

Low -impedance measurement of surface -mountcomponents are trickier due to their increasingly smallersizes. HP Instruments used a test fixture like a small viceto hold the SMD chip and make a four -terminal connectionthat was mechanically stable.

Fixtures for measuring chip components at lowimpedance are still in the development stage as surface -mount components continue to shrink in size due marketrequirements such as smaller, lighter mobile phones. High -impedance chip components are not a problem for thereasons explained and can be measured with a tweezerstyle two terminal clip on probe, Fig. 8b). For generalfour -terminal connections, Kelvin clips are very useful,Fig. 8c).

Extending the frequency rangeUsing a mixer to down -convert the stimulus frequency intothe more manageable audio range can extend thefrequency range of an LCR instrument using thetechniques described.

Again, as for the phase -sensitive detector, an ultra -linearmixer is essential to accurately translate all the amplitudeand phase information in the Eu and ES signals to betweenone and 10kHz where the detector circuits can operate atmaximum efficiency. This in turn requires an accurate,low -drift crystal local oscillator.

Imagine for example that you design an instrument tohave 0.1% basic accuracy and operate at 1MHz with adown conversion to 10kHz. The crystal oscillatorfrequency must be 0.990MHz with an accuracy of around0.005 to 0.01% in order to budget for other errorcontributions. Assuming an operating temperature range of20 to 30°C, you would need a crystal temperature driftbetter than 50/10, or 5ppm.

Example of a modern LCR meterThe LCR400 is a mid -range precision instrumentcosting around f600 excluding VAT. Its basicaccuracy is 0.1% for L, C and R measurements.Three measurement frequencies are availablebetween 100Hz and 10kHz. The instrument isfully autoranging (with range hold) and can alsoautomatically select the function based upon thecomponent inserted. It has dual five -digitdisplays using large and bright LEDs. The seconddisplay is used for the secondary parameter of Qor D and is also used with the limits comparatorfor showing binning information.

The LCR400 has a built-in four -terminal testfixture that accepts most wire -endedcomponents directly. A pair of plug-in pillaradapters enable axial components, such asbandoliered resistors, to be measured directlywithout bending the wires. The position of thetest fixture on the instrument ensures that

component bandoliers can be handled withoutinterfering with the display or keyboard.

An external test fixture can also be used and acapacitance null function allows up to 100pF tobe nulled out. A switchable bias voltage isprovided for polarising electrolytic capacitors.The instrument incorporates a full limits

For minimum switching the down converter uses thesimple half wave PSD circuit described earlier driven by asquare wave at the local oscillator frequency. In practice,the circuit needs to be differential, requiring two samplingswitches for the high and low sense inputs, Fig. 9.

Current steering with very precise make before breakswitching is needed to minimise charge injection from theswitch self -capacitance. The momentary transient on thevirtual earth is too short to be seen by the operationalamplifier, which is in effect isolated by the self-inductanceof the virtual ground. The large unwanted low -order IP ormixing products at 1.97MHz - the difference between thethird local oscillator harmonic and 1MHz stimulus - and1.99 MHz - the sum of local -oscillator fundamental andstimulus - is removed by the series resonant trap filters.All the other remaining higher frequency products arerejected by band limiting the following stages.

Once down -converted and filtered, the Eu and E, signalsare processed as before. This technique works well forpure components like polystyrene capacitors where theunknown impedance is very linear and will not add intermodulation products.

Using this method, specialised LCR instruments havebeen developed for accurate high-speed production testingof plastic film capacitors where D factor measurement at1MHz and capacitance measurement at 10, and 100kHzare required.

Apart from air -cored types, inductive components areusually more quasi -linear due to their core materials.Either the inductor accuracy specification must beloosened or higher order filtering provided in the detectorcircuits to prevent inter modulation products appearing atthe PSD.

In his next article on this topic, Alan looks at LCRmeasurement developments, aliasing and FFT. He alsopresents a review of A -to -D converter technologies that areappropriate for high precision measurements - includingsigma -delta.

comparator with binning. Up to 8 pass bins canbe defined along with two fail bins and binningcan be used can to sort different tolerances ofthe same value or multiple different values.

A numeric keyboard allows rapid setting up ofbinning values. Non-volatile memory isprovided for the storage of up to nine completeinstrument set-ups. Distributed by TTI, theLCR400 has a steel case and large high -grip feetthat keep it in position while components are

passed through the test fixture. This is an.essential requirement when measuring largenumbers of components in an inspection area.

An RS232 interface is incorporated whichallows connection to a PC and can be used toset up all measurement and sorting functions aswell as store readings. PC software is suppliedwhich allows both set-up and results logging.http://www.tti-new.com/

January 2003 ELECTRONICS WORLD 25

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RD Research launches new version of B2 SpiceThe new B2 Spice v4.2 featurescircuit animation, which showswires changing shape to reflectcurrent and voltages, and partschanging colour to reflect heatdissipation. Relative voltagesare colour -coded to magnitudeand arrows display the actualcurrent paths as they flowwithin the circuit. Circuits canbe animated with respect to destepping, frequency sweep andtime.

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Emulator can bereprogrammed on flyHitachi's latest microcontrolleremulator has been designedusing FPGA technology, whichlets emulator functions bereprogrammed during use for thefirst time. According to thesupplier, this lets the emulatoroffer many features that have notbeen available before, includingenhanced breakpoints and PinView and Pin Set. The use ofFPGAs will also let new featuresbe added electronically in thefuture, for example as adownload. The Pin View and Setfeatures allow a device's I/Opins to be viewed and stimulatedbefore the users hardware isavailable. at any time, users canboth toggle an I/O pin from thekeyboard and read the set valueof the pin. The compactEmulator is integrated into theHitachi Debugging Interface(HDI) version five front-end,giving the developer seamless

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access to its advanced debuggingcapabilities. The tool does notneed an internal interface card tocommunicate with the hostmachine as it uses the USB portnow shipped as standard on mostPCs. The first version of theCompact Emulator, theCE2148R, has been released tosupport the H8S/2148F series of16 -bit microcontrollers, whichincludes more than 30 devices invarious package and memorysizes. Members of the serieshave various 8 and 16 -bit timers,on -chip watchdog timers, up tofive serial interfaces, up to 24channels of A/D and up to 82 I/0pins.HitachiTel: +44(0) 1628 585161www.hitachi.-eu.com

Free C compilersPIC16 variantsComputer Solutions is offering arange of C compilers thatsupport the latest range ofPicmicro processors fromMicrochip, along with a freeversion for some PIC16 variants.The Hi -Tech PICC compilers arebased on the full ANSI Cspecification, and incorporate anintegrated edit, make and linkenvironment that allowscompilation, assembly andlinking to be carried out using asingle command. Also includedis a command line drivencompiler that lets it be used within -circuit emulators such as thepopular MPLab. Features of thecompilers include multipleoptimisation levels which takeparticular note of the PIC

architecture. For example, thelinker includes overlaying oflocal variables to reduce RAMuse. A library includes sourcecode and 24 and 32 -bit floating-point support. The compiler alsohas the ability to carry out mixedC and assembler programming.Computer SolutionsTel: +44(0) 1932 829460www.computer-solutions.com

Voltage regulator has9.5pV noise figureMicro Analog Systems isoffering a low noise regulator(MAS9123) in a true CSPpackage measuring 1.0 by1.3mm. Package height is0.65mm. It has a noise level of9.5µVrms (10Hz to 100kHz).Also, noise spectrum dropsrapidly to a low level at lowfrequencies (about 6kHz), saidthe supplier. The device's start-up time with load is 201.ts. Thispackage is also available forother MAS single outputregulators.Micro Analog Systemswww.mas-oy.com

Dual digital pot with32 tapsXicor has introduced a dual 32 -tap digitally programmablepotentiometer IC for audio

Users can configure AC -DC power suppliesLambda has extended theconfigurability of its Vegarange of switch mode AC -DCpower supplies with a controllerboard and software that allowsusers to set up and monitor theperformance characteristics ofsupplies.According to Martin Southam,Lambda's sales and marketingdirector, the intention has beento provide a level of user

control which was previouslyonly available in full customdesign supplies. "It will allowusers to program the powersupply parameters beyondsimple voltage and currentprogramming," said Southam.Called Vega Smartplus, thesupplies include an 8 -bitmicrocontroller board whichcan be programmed via astandard RS232 or RS485 serial

interface. This can be used tomonitor and adjust functionssuch as output voltage, currentlimit, sequencing, status signals,operating hours and fan speed.Up to 32 output units can becontrolled by the controller'sassociated soft -parameters, suchas fan fail signal polarity andDC good signal polarity. Thereare up to five outputs in theunit, which can be individuallyset up and configured by theuser. Each output can have itsvoltage set point adjusted andstartup delays can be applied forsequencing outputs. Thesupplies are compatible with theexisting Vega range and comewith 450 and 600W ratings.Input voltage is from 90 to264V AC. Adjustable outputsare from 1.8 to 62 V.LambdaTel: +44(0) 1271 856666

applications.A resolution of 6 -bitfor 0 to -62dB of audio levelcontrol range, plus a 90dB mute,make it suitable for adjustingaudio signals in preamp stages.The X9460 has -102dB ofchannel crosstalk, and noise plusdistortion at 95dB below signallevels. A zero -crossing detectioncircuit eliminates audible clicksduring wiper changes. Its digitalinterface allows either serialtwo -wire communications orbasic up and down control of thewiper positions. Up to fourX9460 devices can be addressedwithin the same system by usingthe two address pins.XicorTel: +44(0) 1993 700544www.xicor.com

USB debug probedownloads withoutROMA plug -and -play USB hardwaredebug probe from Green HillsSoftware together with the GreenHills Multi 2000 source -leveldebugger and integrateddevelopment environment (IDE),for debugging embeddedprograms by providing programdownload and run controlwithout the need for a ROMMonitor.The Slingshot probe will supportmost major 32 -bit and 64 -bitembedded CPU and DSParchitectures, includingPowerPC, ARM, MIPS andColdFire . It gives users accessto and control over targetprocessor's so they can uploaddata from the target processor,run, halt, and reset the processor,read from and write to processorregisters and memory, single-step through code, and setbreakpoints. The probe isavailable for Windows98/ME/XP/2000 and connects to

NIB

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28 ELECTRONICS WORLD January 2003

122002

NIC COMPONENTS

Station Road, Cullercoats,Tyne & Wear, NE3O 4PQ

Prices Exclude Vat i1117Y296.UK Carriage £1.50 (less than lkg) lea;

£3.50 greater than lkgCheques / Postal orders payable to

ESR Electronic Components.PLEASE ADD CARRIAGE 8 VAT TO AIL ORDERS

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PCB Production - Development0.1" Copper StripbeardSize Tracks/Holes25 x 64mm 9T / 25H £0.2464 x 95mm £0.8795 . 127mm 361 / SOH £1.4195 . 432mm 36T / 170H £4.39100 . 100mm 39T / 38H £1.40100 . 160mm 39T / 63H £1.80100 . 500mm 39T / 199H £6.20119 . 455mm 46T / 179H £5.40

£1.99Strinyyo rd track cuttner

Tie Points & Size Power Rails390 81 x 60mm 2 £2.75840 175 x 67mm 2 £4.86740 175 x 55mm 1 £4.03640 175 x 42mm 0 £3.08Many other sizes available,also lump wires & matrix board. -

PCB Production - Drafting MaterialsA4 Artwork Film (per 10 sheets)Clear Manual Film £1.25Clear Laser Film £1.75White HQ Laser Film £4.62Etch Resist Pens"Dale" Pen £2.70"St edtler" Fine Pen £0.88Etch Resist TransfersSeno mixed DIL pods £2.24 Ai/.Seno mixed Rnd pods £2.24 sus um "--.

'1'1Alfac mixed pads £1.74Alfac mixed lines £1.74 'mum.

Transfer Spatular £1.25We carry the full range of Seno & Alfac PCB transfers,see our catalogue for full details.

Soldering IronsWe carry in stock a wide range of soldering iron andsoldering accessories. Irons from 12 to 100 Watts.15W 240V Low cost £2.8020W 240V Basic £3.7425W 240V Ceramic £14.0530W 2410V Basic £4.68Dose der PumpsBasic 165 x 18mm0 £2.85Antistatic 195mm £3.92Antex Mini 198mm £6.02Antex Pro 210mm £10.26

&Adoring StationA 30W adjustable temperature solder-ing station with a rotary dial on -offswitch, iron holder and tip c)eaningsponge. This station features a quick I #start circuit for rapid heating, ad-justable temperature rangeof 250 - 450 C, Silicone ca-ble and silicone coveredhandle.Supply: 240V, Iron: 240V 30W

Model 167-510 £32.18

&Adoring StationA 48W adjustable temperaturesoldering station with a rotary di-al LED Temperature metering, on.off switch, iron holder and tip clean-ing sponge. This station features ac-curate heat sensing for instantcompensation & stable tempera-tures. AdLustable temperaturerange of 150 - 420°C, Low volt-age iron with Silicone cable.Supply: 240V, Iron: 24V 48W

Model 167-540 £44.50

Soldering StationA 48W adjustable temperaturesoldering station with a rotary di-al, Digital Temperature Indication,on -off switch, iron holder and tipcleaning sponge. This station fea-tures accurate heat sensing for Agit,instant compensation & stabletemperatures. Adjustable tem- AP .perature range of 150 - 480°C,Low voltage iron with Silicone VI -cable.Supply: 240V, Iron: 24V 48W

Model 167-570 £58.75

CCTV - Bleck & Whit. ModuloA miniature CMOS camera modulewith a 3.6mm F2 Lens, video output &power via connectors provided.spotPower:s

12Vdc 50mAVideo System: CCIRPixels: 352 x 288Min Illumination: 0.5LuxVideo Output: 1 Vpp, 75.Dims: 35 x 35 x 28mm 20g .127.73

Range0-500A0.100pA0-500mAal rrIA0-10mA0-50mA0-10OrnA0-500mA0-1A0.3A0-5A0-15A0-10V0-15V0.30V± 500A

PCB Production - Precessiag IquipamontWe carry a large range of the photographic & chemicalprocessing for PCB production, a full list withfull technical specifications is available in our catalogueor vist our web siteUV Exposure oohs2 x 8W Tubes, 6 min timer229 x 159mm working areaModel 332-002 £88.784 x 15W Tubes, 7%, min timer330 x 260mm working areaModel 332-004 £194.51Meineical PreussingLow cost plastic tray -£1.50Process tanks feature electricallyoperated pumps and/or heaterswith thermostat control suitablefor boards upto 320 x 260mm.Universal Tank with heaterModel 333-007 £161.60Bubble etch Tank with heater& bubble pump.Model 33,5004 £198.50 Any of those Items, cornoge £5.50

PCB Production - ToolsDrill BitsHSS parallel shank bits available in sizes from 0.3mm to2.0mm0.3-0.95mm in 0.05mm steps £0.60ea £4.00/101.0-2.0mm in 0.1mm steps £0.40ea £3.60/10HSS Reduced shank (2.35mm) bit available in sizes from0.6mm to 1.7mm in 0.1mm steps £0.84ea £7.60/10Reground Tngsten carbide reduced shank (3.2mm) avail-ablein sizes frprn 0.6 to 1.6mm in 0.1mm steps £1.90Drilling MachinesExpo reliant 12V drill, 3.8mm capacity, 8400rpm £12.78

Minicraft MX1 230V,8000 - 21000rpm withchuck & collet.Model EPE270-390 digNormal price £48.51

- SPECIAL OFFER PRICE E31.02

Servisol ProductsAerosols200m Switch Cleaner200m Freezer400m Foam Cleanser400m Cleaner / lubricant75m1 Vide Head Cleaner200m Aero Klene200m Aero Duster250m Cold Clean200m Label remover40Qm Isopropyl alcoholTubes25g Heatsink Compound50g Silicone grease

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available from www.esr.co.ukEducational KitsThese kits are an ideal way to start you interset in elec-tronics. They freature re -useable components which areattached via springs & wires and easy step by stepguides to make a range of exciting protects. The 300 -in -1leaturs a breadboard -for more complex circuits.

30 -in -1130 -in -13007in-.1

£12.80£32.00£55.20

Panel MotorsHigh quality analogue panel meters, class 2, zero pointcorrection, mirror scale and prewired for panel illumina-tion. Meter size 46 x 60mm, Cutout size: 38mm0.

Int ii6k51k04300200512061020065001260m020rnil12m04rnS110k15k30k

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All meters £5.89 each6V Lamps £1.23 /pair

CCTV - Colour ModuloA miniature colour CMOS camera mod-ule with a 3.6mm F1.2 Lens, video output& power via connectors provided.SpecsPower: 12Vdc 150mAVideo System: PALPixels: 628 x 582Min Illumination: 3LuxVideo Output: 1 Vpp, 75 -Dims: 28 x 28 x 28mm 20g E33.75

PCB Production - LaminatesCopper clad - paperSingle sided low cost paper composite board100-. 160mm Board £0.44100 x 220mm Board £0.62160 x 233mm Board £1.02220 x 233mm Board £1.408" x 12" Bgarcl1.70Copper clod - glass Mr*Single & Double 1.6mm 305 /m'10ID-. 160mm Single £0.85q100 x 220mm Single £1.18160 x 233mm Single £2.29220 x 233mm Single £2.888" x 12" Single £3.44100 . 160mm Double £0.88100 x 220mm Double £1.25160 x 233mm Double £2.30220 x 233mm Double £2.908' x 12ce"DqusIst bleoated £3.22Phete C1.6mm 35 micron Pre -coated with a high quality photore-sist layer. Available in low cost paper composite orGlass fibre, Single & Double sided. Other sizes alsoavailable.

PaperSize Single4 . 6" £1.476 x 12" £4.209 x 12" £6.3010 x 12" £8.1912 x 12" £8.26100 x 160mm203 x 114mm220 x 100mm233 x 160mm233 x 220mm

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PCB Production - Chemicals100m1 Aerosol Photoresist spray, covers 2m'50g Powder developer, makes llt500g Powder developer makes 10It250g Ferric Chloride Pe(lets, makes 500m1500g Ferric Chloride Pellets, makes llt2 5kg Ferric Chloride Pellets, makes 5111.1kg Clear Fine etch crystals, makes 5It90g Tin PlatingPowder, makes llt200m1 Aerosol Flux spray110m1 Aerosol PCB Laquer spray

£4.25£1.09£7.08£1.68£3.04£9.84

£17.58£11.58£3.41£3.63

Magnifying Desk LampA high quality scratch resistantmagnifying glass fitted to a bal-anced swivel arm and deskmount. An integral flourescenttube provides illumination.Magnification: 3x Lens: 120mm0Tube: 22W Daylight simulation.

Model: 028-205 £28.80

Tools - Cutters a SkippersWe carry a wide range Orsecialist tools for the elec-

Sido Cfryouics

inorndersustry including:

130mm Low cost £1.99115mm Draper £2.38115mm Box Jointed £4.26145mm Long reach £3.40Wire Strippers130mm Low cost £2.30150mm Draper 5mm0 £5.86

Tools - Ratchet Crimping PliersHigh quality ratchet crimping pliers for various terminalsincluding Automotive, Data, Power and Data connections.Red / Blue / Yellow £16.00BNC /TNC RF series £15.68RJ11/12 Data Series £18.97RJ45 Data Series £21.20RJ11/12 &45 Series ..£16.80CKft Tools Crimp PROWSGreen/Red/Blue £24.38Red/Blue/Yellow £21.420.24-2.5mm' crimps £24.350.5-6.0mm' crimps £24.35Non insulated crimps £24.38

Tools - Insulation Displacement Connectors (IDCITwo tools suitable for use with IDC ribbon cable connec-tors and Krone® sytle data connectors.

IDC Ribbon Cable £11.80Krone Punch down £10.32

Cable - Ribbon7/0.127mm Grey ribbon cable on a 0.05" 1.27mm pitchwith a red identifying stripe. Supplied by 305mm (Ift) oron full 30.5m DOOM reels.Size per 305mm per Reel10 Way £0.10 £5.3614 Way £0.14 £7.50io way20 Way26 Way34 Way40 Way50 Way60 Way

£0.20 £10.72£0.26 £13.94£0.34 £18.22£0.40 £21.44£0.50 £26.80£0.64 £33.92

CCTV - Complete SystemsWe carry the full range ofMicromark Black & White andColour CCTV systems for thehome or office.These complete easy install sys-tems are supplied complete withpower supply, cables and allfixings. Simple plug-in connec-tions - no soldering requiredfor use with any TV or Video witha start socket.

Black & Whit. Systemsfrom £22.97

Tel: 0191 251,11363 Fax: 0191 2522296 Entail: sales@esr.ce.uk //www.esralo.uk

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the host computer via a USBport. Connection to the targetprocessor is via industry -standard debug ports such asJTAG, EJTAG, COP and BDM.The probe is equipped with anembedded 32 -bit processor thatenables it to achieve host/targetdownload speeds of 10 to100kbytes. It requires no externalpower supply and consumes notarget power, deriving its powerfrom the host via the USB port.Green Hills SoftwareTel: +44(0) 1844 267950www.ghs.com

15V digital pot hasfour channelsAnalog devices has introducedthe AD5263, its first 15V, quadchannel, 256 -position digitalpotentiometer with a selectabledigital interface. A 15V supplycan be used with 0 to 15Vsignals, or a dual ±5V supply canbe used with ±5V signals.Controlled from a pin -selectablethree -wire SPI or a two -wire I2C-compatible data interface, thedevice performs the sameelectronic adjustment function asa mechanical trimmer, variableresistor or potentiometer. Each ofthe four channels contains afixed resistor (20k, 50k or200k0) with a wiper contact thattaps the fixed resistor at a pointdetermined by the digital codeloaded into its register. It placesthe wiper in the mid -scaleposition at power on. A harddrive override shutdown featureshorts the wiper to the Aterminal without disturbing thewiper register contents. In I2Cinterface mode, reset andshutdown can be individually setfor each wiper, and the currentwiper position can be read backby the microcontroller. It isavailable in a TSSOP-24package and operates from -40to +125°C.Analog Deviceswww.analog.com

Taping down heatsinksto plastic BGAsThermatch T410 thermal tapefrom Chomerics has beendeveloped for bonding heatsinksto hot running devices. Thethermally conductive material issuited to applications that requireheatsinks to be bonded to plastic

Ball Grid Array (BGA) devices.The thermal tape has an overallthickness of 0.18mm, andfeatures a 0.05mm aluminiumfoil carrier that is coated on oneside with a silicon based pressuresensitive adhesive (PSA).ChomericsTel: +44(0) 1628 404000www.chomerics.com

Low-cost Bluetoothprotocol analyserAvailable from YokogawaMartron, the Mobiwave D10 is alow-cost Bluetooth protocolanalyser that is designed to testto see if equipment is performingto design standards withoutinterfering with network traffic.The non -intrusive test capabilityis important in monitoring thecommunication status across anetwork, since Bluetoothperforms master/slaveinteractions and uses frequencyhopping to reduce noise effectsand maintain data security.Costing only one-third the priceof any existing non -intrusiveprotocol analyser with equivalentcapabilities, the unit is capable ofanalysing the baseband andupper layers. The user interfaceallows synchronisation and datacapture to be performed, andanalysis and display softwareallows each layer to be examinedin detail.Captured information is relayedto a host PC via an Ethernetconnection real time, allowingremote logging and equipment

Differential connectorsHigh-speed differential signalconnectors for next generation6.4Gbit/s telecoms andInternet backplanes andmeasurement and controlsystems have been added toHonda's NCB hard metricseries. Based on current 2mmhard metric packaging, therange has 1EC917 (DIN43355)and IEC61076-4-101compliant contacts offeringhigh signal density forcompact performance. Usingcontacts with C -shapedconfiguration, the backplaneconnectors are designed toensure good mechanicalcontact stability and eliminatePCB through -hole damage.They are based on press -fit

sharing. The network interfacesupports both stand-alone andLAN configurations.An audio extension moduleallows audio data extracted fromSCO packets to be played backor stored in PCM Wave orCVSD format. This offers ameans of verifying audio -relatedproblems like echo, static noiseand battery power consumptionfor developers working onheadset, handset, audio gatewayor telephony products.The instrument supportsBluetooth protocol layers.Yokogawa MartronTel: +44(0) 1494 459200www.martron.co.uk

40Gbit/s optical testAgilent Technologies hasintroduced its Omniber ()TN40Gbit/s communicationsanalyser, a multi -rate test set fordeveloping and qualifying linecards, modules and subsystems.equipped with all line rates from52Mbit/s to 40Gbit/s plus

technology (solderlessconnection), and are thusunaffected by heat stress orflux cleaning. The firm isoffering the range with 55, 95,110 or 125 contacts.HondaTel: +44(0) 1793 523388www.hondaconnectors.co.uk.

10.71/43gbit/s optical channel(OTU-2 and OTU-3), theanalyser's capabilities includeintrusive through mode forSonet, SDH and OTN at 40 and43Gbit/s. At 43gbit/s, theanalyser provides ITU-T G.709 -compliant. OTU-3 testing withforward error correction analysisand error -add capability.This lets engineers simulaterealistic network conditions andspeeds network equipmentmakers' transition to OTN.There is validation of deviceconformance to Telcordia andITU-T through the analyser'sability to generate structuredsonet, SDH and OTN signals andtest compliance in one box.Agilent TechnologiesTel: +44(0) 117 952 8405www.agilent com

Low power analogueswitchesIntersil has added to its low -voltage analogue switch line.The ISL84514 and the ISL84515are single -pole single -throw(SPST) switches. The ISL84514has normally -open (NO) contactswhile the ISL84515's contactsare normally -closed (NC).Aimed at battery -poweredapplications, power consumptionis less than 5p.W. Leakagecurrent is up to InA. Switchingspeeds are specified at ton =150ns maximum and toff =100nsmaximum. The supplier provides

Olt

30 ELECTRONICS WORLD January 2003

.11.1.11

Signal Wizard 1.6Real -Time Digital Filter

Signal Wizard 1.6 (formerly RTDF) is a unique real-time audio -bandwidth digital filter system with infinitelyadjustable characteristics - all available at the click ofa button. It uses a DSP unit that runs the filter and afriendly Windows -based interface that allows you todesign and download any kind of filter you like, allwithin seconds. You don't need to know about filtermaths, DSP or analogue filter design - all you need toknow is what kind of filter you want. With SignalWizard you can do more than specify the gain of thefrequency response - you can also specify the phaseof any frequency, with a resolution of one hundredthousandth of a degree! If you don't want to botherwith phase, Signal Wizard will design with total phase --free distortion, no matter how complex or sharp thefilter is. You are not limited to the design tool interfaceeither - you can also import frequency responses astext files, specifying just magnitude or magnitude andphase. Once you are happy with the design, justdownload the filter and run it in real-time. Low-pass,High-pass, multiple -band or arbitrary are all possible.

Si nal Wizard 1.6- Ke features

Runs under Windows 95, 98, Me, 2000, NT and XP.Multiple pass, stop or arbitrary filters.Import mode for arbitrary frequency response.Zero -phase distortion or arbitrary phase.Rectangular, Bartlett, Hamming, Nanning, Blackman orKaiser window functions.Deconvolution (inverse) or flipped filter options.Single (18 -bit) or dual channel (16 -bit) modes.Plots impulse and frequency responses as magnitude,dB, square, root, real, imaginary or phase.Extensive filter analysis statistics.Animate facility for tap adjustment.Impulse and frequency responses exportable as textfiles for off-line processing and spreadsheet analysis.Real-time gain and sample rate control.Filter module holds up to 16 filters.Eleven sample rates from 48kHz down to 3kHz.Normal or turbo mode.Maximum input and output level 3.5V pk-pk.

System includes:

DSP filter board.Signal Wizard 1.6 CD.Integrated help files and tutorial.RS232 and analogue I/O cables with adaptors.Power supply.

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data sheets with enhanced devicecharacterisation data for theseswitches, which includecomplete specification tables at+3.3, +5 and +12V andspecifications measured over thefull temperature range.They are available in eight -leadSOIC and five -lead SOT -23packages.IntersilTel: +44(0) 1276 686886www.intersil.corn

Motor controller hasDMOS driversThe A3936 from AllegroMicrosystems is a three-phasebrushless DC motor controller -driver IC with 3A DMOSoutputs and on -chipcommutation logic.Features include DMOS 50Voutputs, synchronousrectification, 3 and 5V logiccompatibility and configurableslow, fast and mixed -decaymodes. Synchronous

rectification of the DMOSoutputs is done on chip. Thisimproves the thermal efficiencyof the IC during PWM operation,and eliminates the need forexternal diodes. The device willoperate with motor supplyvoltages up to 50V and motorwinding currents of 3A.Allegro MicrosystemsTel: 00 33 4505 12359www.allegromicro.com

4.5GHz relay usesmagnetic latchTeledyne Relays is offering a4.5GHz magnetic -latching relaythat features low inter -contactcapacitance for RF performancethrough and beyond the UHFspectrum. Designated the RF180,it has been designed for use inRF attenuators, RF switchmatrices, automated testequipment, spacecraft and otherapplications that require high -frequency performance. Thehermetically sealed relay is

available in three coil voltages -5, 12 and 26.5V DC. It has all -welded construction and featureshigh force/mass ratios forresistance to shock (100G for6ms) and vibration (30G to3000Hz). The relay measures0.475 x 0.375 x 0.300in. (12.06 x9.53 x 7.62mm). excludingleads, and weighs 0.1 ounce(2.9g). Unique constructionfeatures and manufacturingtechniques provide overall highreliability and excellentresistance to environmentalextremes, including temperaturesranging from -65°C to +125°C.The relay can be operated with ashort -duration coil voltage pulse.After the contacts havetransferred, no coil power isrequired. The magnetic -latchingfeature of the RF 180 provides anonvolatile memory capability,because the relay will not resetupon removal of coil power.Teledyne Relayswww.teledynerelays.com

Convertersupplies 15ASynQor has introduced aneighth -brick format isolated DC -DC converter. The PowerQorMega series can deliver up to15A of total output current at3.3V and below and 50W at 5Vand above, without a heatsink.The EML series has a 48Vnominal input (35V to 75V

Reference for real-time clockXicor has a real-time clockreference design that it says isa complete timing circuit forindustrial, enterprise networkapplications and withembedded control systems.Based around a temperaturesensor, microcontroller andthe firm's real-time clockdevices with EEPROM andstandard crystal oscillators, itincludes circuit designschematics and board designlayout files with softwaredrivers for Windows interfaceand example files for C -codedevelopments. The companysaid the design also addressedprecision timing for localisedand distributed -networkclocking systems. These rangefrom synchronisation with anaccurate timing source at the

network level to compensatingfor electronic componentvariation due to differentenvironmental effects. Theaim is to demonstrate thatreal-time clock devicescontaining analogue anddigital timing adjustments cancompensate for crystal

oscillator drift overtemperature and ageing.Initially, temperature valuesversus oscillator compensationadjustments are mapped into alookup table.XicorTel: +44(0) 1993 700544www.xicor.com

range) and meets input voltagetransient requirements up to100V for 100ms.Employing the newly establishedindustry standard eighth -brickfootprint and pin -out, the unitsmeasure 0.9 x 2.3 x 0.35in, (22.9x 58.4 x 9.0mm). They occupy60 per cent of the board space ofa standard quarter -brick and theydeliver full power up to 70°Cwith no airflow (2.5V andbelow). The converter familywill initially be offered at 3.3V,2.5V, 1.8V, and 1.5V withadditional output voltages of1.2V and 5V being releasedshortly. The EML series iscurrently offered with through -hole mounting and will also beavailable in a surface mountconfiguration in Q4 2002.SynQorTel: 0049 9621 600777www.synqorcorn

One chip PBX designhandles 64 channelsMindspeed Technologies hasintroduced a packet privatebranch exchange (PBX) on asingle chip. Designed for bothenterprise and residentialtelephony equipment, theChagall M825xx enables thedevelopment of packet voicesystems with "handset toEthernet" capabilities forbusiness and residential phoneapplications. The M825xxintegrates signalling, encryption,packet processing and signalprocessing functions, handlingup to 64 channels of highlycompressed packet voice on asingle chip. The devicecomprises a DSP core softencryption engine,programmable packet processorand a user -programmableembedded host controller whichis 100 per cent available for userapplications and signalling, andcan support a number oftelephony and packet signallingprotocals including SIP, H.323and H.248. The voice processingsubsystem runs up to 64channels of carrier -class G.7xxcodecs and echo cancellation,supporting packet-to-TDM,packet -to -packet, TDM-to-TDMoperation for up to 512subscriber lines.Mindspeed Technologieswww.mindspeed.corn

32 ELECTRONICS WORLD January 2003

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33

Fig. 2. Interfacefor creating thestepper motordrive sequence.

Two-phasedrive

Fact: most circuit ideas sent to Electronics World get publishedThe best circuit ideas are ones that save time or money, or stimulate the thought process. Thisincludes the odd solution looking for a problem - provided it has a degree of ingenuity.Your submissions are judged mainly on their originality and usefulness. Interestingmodifications to existing circuits are strong contenders too - provided that you clearlyacknowledge the circuit you have modified. Never send us anything that you believe hasbeen published before though.Don't forget to say why you think your idea is worthy.Clear hand-written notes on paper are a minimum requirement: disks with separate drawingand text files in a popular form are best - but please label the disk clearly. Where softwareor files are available from us, please email Jackie Lowe with the circuit idea name as thesubject.Send your ideas to: Jackie Lowe, Highbury Business Communications, Anne Boleyn House,9-13 Ewell Road, Cheam, Surrey SM3 8BZ email Howe@highburybiz.com

Simple stepper -motor driver withforward and reverseOnly one dual D -type flip-flop isneeded here to generate a two-phasedrive. A further quad NOR gate isused to derive the correct wave drivefor the stepper motor and a 555configured as an astable multivibratorclocks the flip-flop, Fig. 1.

Output D1 of the first flip-flopconnects to /Q2 of the second flip-flop while Q1 of the first flip-flopconnects to D2 of the second. InputsS1 and S2 set the flip flops while R1and R2 reset them. These are drivenby push buttons S and R. A third pushbutton, R, reset the astablemultivibrator.

To start with, the flip-flops are resetusing P momentarily. Output /Q2goes high and D1 of the flip-flop isthus held high. At the low -to -highclock transition of the first pulse, Q1goes high and D2 of the second flip-flop goes high. Thus a sequencerepresented by A=1, B=0, C=0 and

7402

Wavedrive

Fig. 1. This two-phase sequencer is clocked by an astable multivibrator.

D=1 is obtained at the first clocking.Now, as /Q2 of the second flip-flop

becomes low, at the next clock pulse,the sequence is A=O, B=1, C=1 andD=0 is obtained.

The sequence repeats. Thus a two-phase drive sequence is obtained to

2N2834

1002W

Fig. 3. Drivecircuit for oneof the fourstepper motorwindings. Theother three areidentical.

Motorwinding

run the motor in one direction.To reverse the direction, the set

push button switch is pressedmomentarily. Now the sequence at thefirst clocking becomes A=0, B=1,C=1, D=0 and A=1, B=O, C=0 andD=1 at the second clock pulse.

Figure 2 shows the wave driveinterface using NOR gates. For onedirection, the wave sequence is A'=0,B'=1, D'=0 for the first pulseand A'=0 , B'=0, C'=0, D'=1 for thesecond. If the stepper motor gets stallsdue to noise for example then setpress the set or reset push button.

Figure 3 is the power amplifier forone phase only. The remaining threeare the same.V. GopalakrishnanBangaloreIndia

34 ELECTRONICS WORLD January 2003

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anuary 2003 ELECTRONICS WORLD 35

CIRCUIT IDEAS

Precision full -wave rectifierHere is a circuit that rectifies alter-nating signals. Such a circuit hasquite a few different names and canbe used in a variety of applications.

In a wireless, the circuit would becalled an AM full envelope detector.This circuit would be equally athome positioned in the front end ofan RMS detector and is then referredto as an absolute circuit. I will referto the circuit as a full -wave rectifier,or FWR, from now on.

Using the components shown inthe diagram, this FWR will rectifyup to about 2MHz, with inputsignals as low as 10µV. I originallyused it for full envelope detection ina 455kHz IF chain. It may bepossible to squeeze more speed outthe circuit by reducing /28/Rio.

There are numerous applicationsfor this precision full -wave

rectifier, which accepts inputsignals as low as 10pV and

frequencies to 2MHz.

£50 winnerR

Single -endedinput

12VR13

150

The input can be driven differen-tially or from a single -ended source.Assuming a single -ended input thenthe input signal is split into twoequal parts, 180° out of phase withone another.

Splitting is performed by the long-tailed pair Tri and Tr2. The tworesulting signals drive two emitterfollowers, Tr4 and Try, connected inconjunction with Tr7 and Tr6, whichserve as local current feedbackpairs. This action ensures superlinearity right down to themicro -volt region-i. e. constantbandwidth with wide dynamicrange.

Transistors Tr4 and Try conductalternately and the summation of thetwo emitter currents results in full

R146k8

VR 220

C2 R

7100n 1k2

R4

R2Tr3 56k

10k %EV 2N3904R3

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R8

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R9

5k6Tr7

2N3906

C3

100nR23

5k6

Four 741 op -amps are used here to indicate voltage via four on fourLEDs. These LEDs indicate turn on sequentially as the voltage exceeds 3,6, 9 and 12V respectively.

Inverting inputs (pin 2) of ICs 1-4 are supplied with 3, 6, 9 and 12 voltsfrom the resistive divider chain. The non -inverting inputs of all four op -amps are tied together and form the meter's input terminal.

As soon as the applied voltage exceeds the reference voltage of one ofthe o-amps, it will bring its output high and activate the appropriate LEDindicating that the voltage has been reached. You could use a quad device,such as an LM324 instead of the four op -amps.Raj GorkhaliKathmanduNepal

wave rectification across R22.

The DC static offset voltage willbe in the region of 6V or aboutVie/2. It can easily be removed byan op -amp, leaving just the rectifiedsignal for further processing. Thegain produced by long-tailed pairTri and Tr2 is about seven. Thissuited my needs at the time.Obviously though, this gain can bechanged to suit other applications.

Adjust VR1 to balance the rectifi-cation action with the aid of anoscilloscope. The whole circuit runsfrom a single 12V supply. Mostimportantly, the circuit is incrediblycheap.Darren HeywoodBuckleyFlintshire

R1627k

Tr4

2N3904x2

R2068

1222k2

- Output

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36 ELECTRONICS WORLD January 2003 00

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Build and Upgrade Your Own PCSecond Edition

0 Save £100s by making your current PC last longer0 You can have a PC with a spec that matches your needsO Discover the practical techniques of upgrading a PC and avoidthe pitfalls

Ian Sinclair's Build Your Own books have established themselvesas authoritative and highly practical guides for home PC users andadvanced hobbyists alike. All aspects of building and upgrading aPC are covered; making this the book the computer retailers don'twant you to read! By getting to grips with the world of PChardware you can avoid the built-in obsolescence that seems to bepart and parcel of the fast moving world of PCs, and escape theneed to buy a new PC every year. You can also have a PC thatkeeps pace with the ever-increasing demands that new softwareapplications place on your system.

The new edition of this book is based round building andupgrading to the latest systems such as Pentium III and dual -processor Celeron motherboards running Windows 95/98 orWindows 2000. As well as guiding you round the inside of yourCPU Ian Sinclair also covers monitors, printers, high capacity diskand tape systems, DVD drives, parallel port accessories....

CONTENTS: Preface; Preliminaries, fundamentals and buyingguide; Case, motherboard and keyboard; About disk drives;Monitors, standards and graphics cards; Ports; Setting up;Upgrading; Multimedia and other connections; Windows; Printersand modems; Getting more; Index

How to pay(Build and Upgrade Your Own PC) paperback

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Post your completed order form to: -Jackie Lowe, Highbury Business Communications,Anne Boleyn House, 9.13 Ewell Road, Cheam, Surrey, SM3 8BZ

UK Price: £22.50 Europe £24.00 ROW £26.00 Price includes delivery...111.11Me.,

January 2003 ELECTRONICS WORLD 37

CIRCUIT IDEAS

USB-powered high -precision hi-fi phono preampTable 1. Frequency response of the preamplifier.

Freq. (Hz)11.8

Test (dB)61.4

Ref (dB) Error

20 59.17 59.3 0.1340 57.44 57.8 0.36100 53.68 53.1 -0.58200 48.52 48.2 -0.32500 43.12 43.2 0.081000 40.83 40 -0.832000 38.41 37.4 -1.015000 33.28 31.8 -1.4810000 27.82 26.3 -1.5215000 23.85 22.8 -1.0520000 21.53 20.4 -1.13

5V o MAX8877

SHDNOUT

GND BP

10n

0 3.3V

3.3p

Fig. 1. Power for the preamplifier 's derived from the +5Vline of a computer's USB interface. This circuit converts thenoisy 5V output to a regulated +3.3V for driving thepreamplifier.

Fig. 2. One channelof the phonopreamplifier.

Fig. 3: Frequencyresponse versus

the RIAAreference.

3.3V

3.3V

A phono preamp is needed forpreamplifying and equalisation theanalogue output of the good oldrecord player. Former hi -tiamplifiers included a phono input.Now though, phono preamplifiersare rare. CD players have a linearoutput that don't need linearisation.

If you still want to play yourrecords or you want to archive LPsusing your computer's sound cardyou may find this phono preampuseful. This application is easilypowered by +5V from thecomputer's USB port supply. Noexternal power supply, dual supply,or mains connection is needed.

The circuit diagram shows a 3.3Vpowered phone preamplifier withRIAA equalisation curve.Compared to other op -ampsolutions, the main advantage ofthis one is that it is a low power,low voltage design and runs from asingle supply.

A MAX4478 quad, low noise, railto rail op -amp is at the core of the

1/4MAX4478820

65

60

55

50

45

40

35

30

25

20

Phono preamplifier amplitude response

e e veFrequency (Hz)

-e- Test (dB]Ref [dB]

design. A small MAX8877 linearregulator regulates the noisy +5Vfrom the USB supply down to+3.3V, Fig. 1. Additionally theMAX4478 op -amp offers a veryhigh power -supply rejection ratio of120dB. This circuit, Fig. 2, isintended for use with the standardmoving magnet type phono pickup.

The high value capacitors of100µF, 22g and 101.1F could betantalum or standard electrolytictypes. The 82nF and 22nFcapacitors should be 2.5% toleranceif obtainable, otherwise you may beable to measure a selection ofstandard tolerance caps to findthose that are closest to the requiredvalue. Some deviation from theideal RIAA equalisation curve willoccur if these capacitors are too farfrom the designated values. Moreimportant is the matching betweenchannels. This should be as accurateas possible.

Resistors should be 1% metal filmfor close tolerance and low noise.This design is done with active lowfrequency and passive highfrequency filtering. Based on theRIAA specification, Table 1 showsthe performance with frequency.There is no rumble filter forfrequencies below 20Hz so becareful with 50-60Hz noise. Thisapplication requires highamplification for low frequencies,at around 60dB (1000) for 20Hz.

As you can see from Table 1 orFig. 3, the accuracy is about 1 dB.This might be increased if a moreaccurate capacitor for the highfrequency filtering is used. Gain atlkHz is about 40dB (100) so anominal 5mV cartridge output willgive 500mV output. This may beincreased, if necessary, byincreasing the value of the 100ki2resistor in the second stage.Martin BaumbachMaxim Integrated Products

1

38 ELECTRONICS WORLD January 2003

a

ELECTRONICSWORLD..

Self on AudioDouglas Self

The cream of 20 years of Electronics Worldarticles (focusing on recent material)

A unique collection of design insights andprojects - essential for all audio designers,amateur and professional alike.

Scientific electronics based on empirical data

Douglas Self has been writing for ElectronicsWorld and Wireless World over the past 20years, offering cutting -edge insights intoscientific methods of electronics design.

This book is a collection of the essentialElectronics World articles, covering twenty yearsof amplifier technology but with a very strongbias towards more recent material. The articlesinclude self -build projects as well as designideas and guidance for the professional audiodesigner. The result is a unique collection ofdesign insights and projects - essential for allaudio designers, whether amateur orprofessional.

Contents: Introduction; PRE -AMPLIFIERS: Anadvanced preamplifier MRPI;High-performance preamp MRP4; Precisionpreamp MRP10; Moving -coil head amp;Preamp '96 I; Preamp '96 II; "Overload Matters"(RIAA overload); Balancedline inputs and outputs, part 1; Balanced lineinputs and outputs, part 2;POWER AMPLIFIERS: FETs less linear thanBJTs; Distortion in power amplifiers1-8; Distortion residuals; Trimodal part 1, 2;Load -invariant power ampINVAR.DOC; Common -emitter amps; Two -stageamplifiers; SPEAKERS: Excessspeaker currents; Class distinction (ampclassification); Relay control;Power partition diagrams; Audio power analysis.

SelfAudioDOUGLAS SELF'

Douglas Self has dedicated himself todemystifying amplifier design and establishingempirical design techniques based on electronicdesign principles and experimental data. Hisrigorous and thoroughly practical approach hasestablished him as a leading authority onamplifier design.

Readership: Audio electronics enthusiasts;Professional amplifier designers;Power amp usersPaperbackPages: 416pp

UK Price: £27.50 Europe £28.50 ROW £30.00

Return to Jackie Lowe, Highbury Business CommunicationsAnne Boleyn House, 9-13 Ewell Road, Cheam,Surrey, SM3 8BZ

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January 2003 ELECTRONICS WORLD

to the editorLetters to "Electronics World" Highbury Business Communications,

Anne Boleyn House, 9-13 Ewell Road, Cheam Road, Surrey SM3 8BZ

e-mail j.lowe@highburybiz.com using subject heading 'Letters'.

Valve amp protectionA word of caution regarding the valve ampprotection circuit (circuit ideas, p31September 2002). In any application of thefloating cathode technique it is advisable tocheck that the heater supply is isolated fromchassis. I remember this system being usedto key transmitters. Where the heater supplywas returned to chassis the output valvesfrequently suffered heater/cathode shortsdue to the high voltage developed betweenthese elements when the cathodes wereallowed to float,W. J. Williamson,North-a-Voe, Yell, Shetland, UK

Free ads page, anyone?May I take this opportunity ofcongratulating you on your new post ofeditor of such a valuable and interestingpublication. Now, during my retirementfrom radio design/development engineeringposts, I still find it very useful.

I strongly endorse the suggestion of a freereader's ads page to help readers locatesources of components and technicalarticles.

I would also appreciate it if full postaladdresses could be published in adverts, etc.,as I find it very frustrating when only awebsite address is given. I am reluctant torun to the extra expense of buying a PC atthe age of 72 - I'm very much in favour ofwritten text.S J Harris C Eng MIEEWhitleigh, Plymouth, Devon, UK

Cable testingCyril Bateman seems slightly to have missedthe point of my article on distortion testingof loudspeaker cables using audio hardwareand software. It seems I was not sufficientlyclear in explaining my aims and intentions: Iapologise.

First, the choice of speaker cable as asubject for the test was only intended to beillustrative of some of the techniques onecan employ with such software (incidentally,the new version of Cool Edit Pro, admittedlymore expensive at $250, has a fullyzoomable spectrum display and the option ofexporting the spectrum, which makes itpotentially nearly as powerful as the verynice Spectra software Cyril uses and avoids

Vibration meter?After 30 years in Australia, I'm residing for a while in Yorkshire,and enjoying Electronics World. As a 66 year old retired ex -industrial instrumentation technician, I'm still keenly interested inthe subject of noise and vibration. My interest stems from workpioneered by Holset Engineering of Huddersfield, a companyrenowned for turbochargers, torsional vibrational dampers andcouplings.

My hearing suffered from many years in the RAF, power stations,and noisy industrial environments, long before adequate protectionlegislation existed. This is mainly 2 - 4 kHz loss in my left ear. Thisis particularly frustrating when trying to hear the radio or CD in mycar.

Most car noise now seems to emanate from hard compound tyresrunning on rough tarmac surfaces. It is exacerbated by non -solidbulkheads in the boot, namely drop down seat backs and is evenworse in hatchbacks! Thus without adequate vibration insulationbetween body and suspension, most cars short of Jaguar, RollsRoyce' etc., are to me very noisy.

Ah, you might say, that's your opinion. That's where my plea to

some of the tedious signal -manipulationtricks I described in earlier articles).

More importantly, however, I shouldexplain my rationale in choosing the testsetup. The entire reproduction chain (CDplayer and amplifiers) was exactly as I use itfor subjective reviewing of speaker cables, inwhich situation I believe I can heardifferences between cables. Typically, thedistortion of the system is dominated by thepower amplifier, but what I was looking forwas any evidence that changing cablechanged the spectrum - in which case by farthe most likely explanation is that theamplifier's performance was subtlymodulated by the cable's parameters, ratherthan that the cable itself is producingdistortion. In using a CD as the signal source(with a 'perfect' dithered 16 -bit digitallygenerated test signal of four sinusoids) and aCD recorder (16 -bit, of course) as theanalogue -to -digital converter, I was imposingrestrictions no greater than those of therecordings with which I believe I can heardifferences between cables. The test is thusfair and legitimate. Of course, real audio istypically considerably more complicatedthan a mere four sinusoids, but one mustdraw the line somewhere.

E.W. readers comes in. How about some articles on vehicular noiseand vibration measurement? In my day Kistler and VibroMeterCorp ruled that roost, but searching the Web for practical/theoryarticles on charge amplifiers/electrometers, cheap piezoaccelerometers and microphones, usually turns up medical papers.

I'm particularly interested in a frugal design for a battery, handheld device, which can measure and display audio noise -weightedA scale (?) 40 - 90 dbA, and vibration 0 - 5g. A sort of poor man'sNVH -noise, vibration and harshness -meter.

The microphone would be integral with the meter. The simpleaccelerometer could be screwed into a small lead block. A movingcoil meter indicator would suffice.

Providing the instrument is reliable and reasonably repeatable,simple subjective calibration could be achieved using a very quietcar - got any Bentley owning friends? - a noisy bus, or a particularlynasty small hatchback.

Have I set a challenge to any E.W. readers? Do you have anycircuits for charge amplifiers? Does pC/g spark off any memories?Over to you!Robert GottKeighley, West Yorkshire, UK

i

40 ELECTRONICS WORLD January 2003

LETTERS

Homage to BaxandallIn their original paper Baxandall and Shallow' gave a qualitativedescription of and measured results for, the circuit (see figure)referred to in the 'Letters' section of the April 2002 issue ofElectronics World.

For readers wishing to exploit the unique advantages of theiringenious scheme, the formulae and design approach given beloware appropriate.

In them: a(3) = common base (emitter) current gain, withcorresponding letter subscript to denote QN, Qp; VA = 'early'voltage; VT = 'thermal' voltage; Ro = L.f. incremental outputresistance, calculated using the approach described in ref 2.

to = (Vz/R3) - apIx, where Ix = (Vcc - Vz - VEB)/R2

Let aplx = Vz /10R3, then lo = 0.9 Vz / R3

Select Vz(s12V) and calculate R3 and R2 for a specified I0assuming VEB = 0.7V. Then calculate Ro 0.9(VANT)(Vz/l0).

For Io = lmA, Vz = 10V, VT = 25mV (room temp value), VA =

Cyril's high resolution distortion tests areimpressive and may even show up effectsdue to cables, but having myself conductedspot -frequency THD tests that failed to showany cable -induced distortion down to about-110dB I wished to investigate other lines ofattack that might perhaps show up somethingat a higher (more plausibly audible!) level.

In conclusion, Cyril's excellent work oncapacitors is clearly much more rigorousthan my own: I merely wished to presentsome food for thought and a few possibilitiesfor further development on the good oldengineering principle of 'what if....?'Richard BlackLondon, UK

More microcontrollers,please1 was going through some recent issues ofElectronics World and found the article"Designing with VHDL" in the May 2002issue. The article was interesting to mebecause I like to see what others do with oneof my favourite subjects. I thought theauthor had done very well to introduce whatamounts to quite a complicated subject in ashort article. I did notice quite a few typo-graphical errors in the text of the article butthe article was readable nonetheless.

The article promises a concluding articlewith a practical application. I have not beenable to find this concluding article so far andthis has been a disappointment. Of coursewe are a couple of months behind receivingthe magazine here in Australia but if thearticle has not yet been printed I would beglad to see it in a future issue of the maga-zine.

In another letter in your magazine onecorrespondent joked that the magazine

100V (typical value for a low power NPN device), Ro = 36MQ: ifVA = 125V, then Ro = 45%2. If R3 is replaced by the output circuitof a high resistance current sink (e.g. a common base stage) then Ro

POP(VA/10). For RN =13p = 100 and VA = 100V, this gives at Io= lmA, Ro = 1000MQ, the value found by Baxandall and Shallowfor their modified circuit.

References1. Constant -current source withunusually high internal resistance andgood temperature stability'.Baxandall P.J. and Shallow E.W.,Electronics Letters Sept 1966, Vol 2,No. 9, pp 351-3522. 'Early Applied', Bryan Hart,Electronics World, July 1999, pp591-594.

Bryan Hart Leigh on Sea,Essex, UK

should be called Wireless World, after a verypopular magazine that disappeared off thenewsagents shelves some years ago. As Irecall the price of the magazine suddenlydoubled when the magazine went glossy andthis must have lead to the demise of themagazine.

It does seem to me that your articles areheavily biased in favour of audio and RFarticles with just the occasional good digitalarticle. Maybe your editor is from the oldschool when ham radio was the hobby ofchoice for the technically inclined. I left hamradio behind about 40 years ago.Microcontrollers and programmable logicare the in hobbies for me these days and Iam not averse to a bit of theory if it makesan important point.

Maybe your editor and readers areunaware of how cheaply you can get startedwith programmable logic these days. Verysophisticated software can simply be down-loaded from the internet or some of thecompanies will send you a CDROM free ofcharge if you request one from their website. With this you can create quite elaborateprojects with little expense on hardware. Ifyou need help getting started you canprobably do a course at your local technicalinstitute or read the article "Designing withVHDL". Check out my web site at:http://users.senet.com.au/-dwsmithDavid Warren -Smith, CPEng, MSc.Elizabeth Downs,South Australia

More microcontrolers 2As a radio ham, the old school of Morsetappers, I hold onto the study of Morse codeas a criteria of holding a licence and Iunderstand why people who have spent theirwhole lives in a particular discipline are

reluctant to change, especially when thedecaying brain -cells cannot keep up with thelatest developments. But technologymarches on relentlessly, and I am afraid thatthe old-timers are going to have to give wayto the youngsters, but us wrinklier can restassured that the youngsters are standing onthe shoulders of giants.

I would certainly like to see morecomputing articles, particularly PICs andDSP, in the future. EW has a reputation for amore academic approach to electronics thansome magazines on the newsagents shelves(such as Elektor and EPE) so please do notdumb down the magazine. The point of yourillustrious journal is that we are gettingsomething that is state of the art, or in someway unique, and unavailable in textbooks.Isn't it about time EW had a website and aCD-ROM archive of past articles.Stan Thomas, UK.

Non -ionising radiationAt times I feel I should respond tocommentaries by the editor, and others ...;since I need to send this email now, acomment on 'mobile phones' and radiation,etc.

A few years ago, 40+, I was asked to lookat the electromagnetic spectrum for anyadverse effects it could have on humans. Iwas given; 'start at Rugby (16kHz) up to thelatest radars' (2GHz), and 0.311M to 15µM,the then laser frequencies.

I vaguely remember my findings were thatthere were many frequency spots and ranges,and threshold power levels and continuouspower levels that appeared to have somehuman effect. These ranged from localburning, headaches, mood changes, etc.

In Australia someone used chickens todetermine any effects by mobile phones;

January 2003 ELECTRONICS WORLD 41

LETTERS

what a load of rubbish! Non -ionisingradiation can be very subtle; so I would say,"Be careful".Remember, I can get drunk on, whisky andsoda, vodka and soda, .... therefore sodamakes you drunk.If this makes sense to you.John Ingram. Gawler, 5118.South Australia.

Capacitor soundCyril Bateman's series on capacitor soundbrings to mind that modern capacitors arein fact quite complex 'devices'. Firstly,fundamental physics by way of thecausality principle, of which some mightbe aware, leads to the famous Kramers-Kronig relation, basically stating that an`ideal' capacitor or for that matter aninductor (i.e. a component with purereactance) is impossible at all frequencies.

Secondly, modern capacitors inparticular (and perhaps even for inductorson special toroids) should be strictlyviewed as semiconductor devices. Theinterface between the metal contacts anddielectrics are actually junction devices ofone sort or another, notably Schottky like.Ohmic behaviour at all voltages, currentlevels and especially at higher frequencies

cannot be expected. Indeed the secondand third harmonic generation reported byBateman, are classic examples of non-linear transfer characteristics typical ofsemi conducting device properties.Capacitor manufacturers should thuspublish data sheets that give deviceperformance, such as S -parameters (likeRF MOSFETs) and even more such asthermal properties, as modern capacitorsfor SMPS are required to dissipateconsiderable power. There is no excusefor this lack of detail, as these 'devices'are costing more than some average powerMOSFETs on the market.Tuck Choy PhD SMIEE MCIMManchester, UK

Spectrum pricingLoved the spectrum pricing article. It wassomething I had suspected, but I didn'trealise how unfair it had been until thatarticle. It was clear and well structured.Would like to see more stuff like Ivor Catt(is he still about ?), he had interestingideas, and the maths articles relating toelectronics as Joules Watt used to write.What about a series on quantummechanics and electrons. Also valves arefun, what about an article describing

Help wantedI am looking for a circuit diagram of a'leak detector' and also a 'cable andpipe locator'. I hope that thesediagrams will be published in the nextissues of EW magazine.Davut EL_K Ankara, Turkey

Any designers with a leaning towardsplumbing care to contribute? - Ed

triodes, tetrodes and pentodes and what allthe plates do advantages/disadvantages,etc. I'd like to see a descriptionmathematical and descriptive of how co -axworks too, loss -less in theory I guess`difficult' maths or physics stuff does noharm, if people can't follow it they turn thepage and look at some adverts orsomething. But true engineers will treat itthe same way a Guardian reader treats hiscrossword. Something to exercise themind! Feed our minds, that's why webecame engineers in the first place... I'dlike a build your own Theremin articletoo. I'll build it. I built the hot audiopower amp in March 1995.Robin Clark UK

No ConspiracyPigeon has homed in on a likely cause of RFradiation induced brain pathologies(Psychosomatic effects'), which suggestskeen insight on this topic - an article byPigeon wouldn't go amiss?

However, a few important signposts havebeen missed: A Spokesman for the industry,interviewed for TV news recently, said "it'snot a conspiracy..." Apparently Cellnetantennae are hidden in petrol filling stationprice hoardings for cosmetic reasons,because they're unsightly; trees and churchturrets are also used! In addition, the newsitem assured viewers that an expert(unnamed) stated that "...the radiation posesno harm", and this, only a few daysfollowing news items about the results ofseveral studies showing strong correlationsbetween right or left hand use of mobilephones and corresponding brain pathologiesbeing treated in three countries.

A better study than amphetamine inducedpsychosis would be to repeat Plenz andKitai's experiment in the presence of1.87Hz, which incidentally, was firstreported by 'Electronics World' in diMario's article on a self build ELF counter.Dom couldn't find the source of the 1.87Hzfrequency - he thought it might be from hisrefrigerator - but it's important to realise

that 1.87 is equal to the quotient of Fl andF2, the bifurcation constants: 4.669....,2.502....Malament suspected thatgravitational forces are determined by theratio (negative) of the Minkowski lengthswhich he dubbed "ponderacmotive". If weput 1.87Hz in the place pendulum equation

(t = f- I = 23P/1/g) we can see that `g/1' isvery close to 137, which Eddington calledthe fine structure constant, considering it tobe a prime arbiter of natural dynamics (27 +23 + 2° degrees of freedom for intervals onfour events, t x y z). If, however, 1.87Hz issubstituted in E = hv = mc2 it gives m equalto 1.375 x 10-54 J.S.cm-2 compared toEddington's value of 9.8 x 10-55cm-2, for Xthe cosmological constant, which Eddingtondubbed the comical constant.

The difference in units is a clue to wherethe 'hard problem' lies in contemporaryphysics (quantum gravity, GUT, whatever?),a fact borne out by Eddington'sprognostications in 'The ExpandingUniverse' (c.u.p 1933). Wey's calculation(1917) shows this most clearly with an orderof magnitude error of 27 (8irk/c = 1,87.10-27cm.gr-I), which isn't removed by changingthe MKS or cosmological units; p/q(Malament) = Fi/F2 (Feigenbaum) is thegold standard now - for physics and mind!

References:1. Deitmar Plenz & Stephen T. Kitai, 'Nature',

400, 12th August 1999, pp 677-682; ibid 621-22. Lawrence Sklar, 'Philosophy and Spacetime

Physics', University of California Press, 1985,page 112.

3. Herman Weyl, 'Space, Time, Matter', 4thedition, Dover Publishers (English), 1952,page 243.

4. Roger Penrose FRS, 'The Large, the Small andthe Human Mind', C.U.P., 1997, page 130 et seq.5. H. Minkowski, Lecture, Cologne, 21st

September 1908; trans. In 'The principle ofRelativity', W. Perrett and G.B. Jeffrey,Methuen, 1924.

6. Sir A. Eddington FRS, 'The ExpandingUniverse', C.U.P. (1933), page 114;k can be used to calculate the radii of emptyand the Einstein universes: Rs = V3. Re, k3/R2s; ibid 'The Mathematical Theory ofRelativity', Chelsea Pub, (NY), 3"I edn, (1975),page 235, 7v = 10-50 cm -2 or much smaller,written in 1922.

A G Callegari BSc., MPHIL. (Lond)Much Hadham, Hertfordshire, UK.

I can't quite work out why it is dangerous touse a mobile phone in a petrol station, butquite safe to have a more powerfultransmitter in the same place. Does anybodyhave an explanation? Ed. irr

42 ELECTRONICS WORLD January 2003MI

LETTERS

MFB ReplyI read with interest John Watkinson'scomments about my MFB speaker system.A simple proof that the circuit acts as aservo can be easily obtained. If you connectan oscilloscope between the output of theamplifier and ground and displace the conemanually the amplifier's output voltage willbe seen to alter as it tries to correct the error.The error of course is the back emfgenerated when the cone is displaced. Nomatter how large a magnet you might use ona driver you will never provoke theamplifier to correct errors generated in thisway. Moreover, this action works across thepiston range of the driver reducing, forexample, re -radiation of internally reflectedsound. A common cause of colouration inreal, as opposed to theoretical speakersystems. The definition of a motionalfeedback system is that the cone's motion isdetected and used to control it's own motionvia the power amplifier. I rest my case.

Actually most of the points raised by Johncan be seen as red herrings if the circuit isclosely examined. The voltage generatedacross the 0.47R resistor, connected in serieswith the speaker is directly proportional to

the impedance of the driver which in turn isdirectly proportional to the back emf. Thisvoltage is compared to the input signal bythe op -amp. Where John is right, however,is that the circuit is not a conventional servosystem. In a normal servo the controlelement would have large open loop gainreduced by signals from the sensor. Anyperformance improvement would be due tothe excess loop gain of the circuit.

The servo used here employs positiverather than negative feedback. The circuit istherefore arranged to have a low forwardgain defined by a conventional negativefeedback loop. Control of the loop gain, andcone motion is obtained by the amount ofpositive feedback applied. The use ofpositive feedback in this way is anadvantage since the control range istheoretically infinite without fear ofpromoting oscillation with any reasonablecomponent values. The circuit produces amodification in the deep bass response bymodifying the 12db/octave slope belowresonance to 6db/octave. FYI analysis of theacoustic output of the system at 20Hzshowed that the THD was reduced from22% to 3%. Addition of the equalisation willactually reduce this further since the THD

measured is a function of the roll -off rate,among other things. 40% 2nd harmonicdistortion at 40Hz is inaudible in thepresence of programme in any event, to putthe above figures into some perspective.

A conventional MFB system as outlinedby John is quite a problem to produce inpractice. Unless an acceleration sensor isemployed, some form of equalisation will benecessary. Even then you'd need to curtailsub audio response unless you could providetruly infinite gain in the amplifier. Anotherproblem would be sensor linearity. Howcould you be sure that your sensor wastelling the truth? It's seems churlish in theextreme to ignore the back emf freelyprovided by the driver. Velocity,acceleration or displacement proportionalsignals can be obtained. Of courseacceleration or displacement signals wouldneed differentiation or integration of thebasic velocity signal. Integrators anddifferentiators are of course a form ofequalisation!

Finally If John has some new thoughts, oreven better a radical design that works, Iwill be grateful to read the article(s). If notwatch this space!Jeff Macaulay UK

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January 2003 ELECTRONICS WORLD 4;

COMPONENTS

Capacitor sound 610-100 F capacitors and 100Hz measurements

Many capacitorsintroduce distortionsonto a pure sinewavetest signal. In someinstances distortionresults from theunfavourable loadingwhich the capacitorimposes onto its valveor semiconductordriver, though moreoften, the capacitorgenerates thedistortion within itself.Cyril Batemanconcludes hiscapacitivedeliberations

For the 1µF value, choosing a filmcapacitor or a bi-polar electrolyticgenerates the lowest distortions. In the

tests, polar aluminium electrolytics producedconsiderably larger distortions, even withsmall AC signals.'

While high capacitance electrolyticcapacitors can be obtained from distributorsat low cost, cheap metallised film capacitorsare restricted typically to 10uF at 100 voltand 22uF at 63 volt. In this final article,which completes last month's discussion onelectrolytic capacitors, we explore whether ametallised film capacitor or an electrolytic isour economic, low distortion choice forcapacitor values between 10uF and 100uF.

Test frequencyTo avoid overstressing large valueelectrolytic capacitors, we should reduce ourtest signal frequency towards 100Hz. Butsufficiently above or below this frequency todiscriminate between harmonics of thesupply mains and the test capacitor. Withminor changes in capacitance values, thePCB used for our 1kHz oscillator canprovide an exceptionally low distortion100Hz test signal.2 In similar fashion thePCB used for our 1kHz notch filter and pre-

amplifier can also be used at this frequency.3The AD811 low distortion buffer can

output 40mA. At 100Hz using a 1000 seriesresistor, it can develop a 5 volt test signalacross a 10µF capacitor. Using a 105.2resistor, 0.5 volts could be developed acrossa 100uF capacitor. These test voltages aremore than sufficient to distortion test anyelectrolytic capacitor up to 100uF. However,when I designed the test instruments Idecided to provide the ability to measureboth values of film capacitors to 5 volts. Toproduce a larger test signal with 100uFcapacitors, a more powerful buffer must beused. A low distortion circuit able to driveup to 400mA has been designed but needs adifferent PCB. Fig. 1

When testing large value capacitors, afour terminal test system is preferred andfour BNC connectors are provided whichaccept either Hewlett Packard capacitor testjigs or four discrete cables and crocodileclips. Fig. 2

Tantalum and aluminiumelectrolytic myths.Some audio power amplifier designs haveused small tantalum bead capacitors, withapparent success. Initial measurements of a

44 ELECTRONICS WORLD January 2003

COMPONENTS

C32

R362k05 0 5

2

R39FROM 511 5%

Buffer_3 sch

R402k05 0 5% R28

OP/OPA620R

OUT

OUT

U5b

NE - Link to Pin 6

\i/-15V OP/OPA - Link to Pin 5

US OP295/0PA2134/NE5532A

50 Ohn Output Amplifier

A5 V

+InOut

-InV

R38A100R 0 5%

41--0

R38100R 0 5%

U6EL2099COn Heatsonk

\415V

14 --I> 13

8

9

I0

12 6

SW12P_6Way_Switch

50 Ohn Output) TO

Use

Use

Use

Use

Use

IOR for 100 uF100R for 10 uF

1k for 1 uF

10k for 100 nF

100k for 10 nF

R3020R

20RR30A

31100 0 5%

32lk 0 5%34

10k 0 5%35

100k 0 5%R37A 0 T

TO

Cdu t

Capacitor under Test

Figure 1: High power buffer provides low distortion, a gain of two and a 400mA output. It can develop more than five voltsacross a 100pF capacitor via a 1052 current limiting resistor.

number of tantalum capacitorsrevealed large distortions. Measuredat 0.3 volts with and without DCbias, my tantalum capacitor stocksproduced at least ten times moredistortion than found with low costpolar aluminium electrolytics. Idecided to exclude tantalum beadcapacitors from further tests. Fig.3

As with other capacitor types,much has previously been writtenabout the sound distortionselectrolytics produce. Most werediscussed in my last article and theremainder will be in this.a) High ESR electrolytics degrade

sound quality, low ESR is alwaysbest.

b) Electrolytics are highly inductiveat audio frequencies.

c) Polar electrolytics should bebiased to half rated voltage toreduce distortion.

d) Electrolytic capacitor distortion ismostly third harmonic.A working knowledge of

electrolytic construction combinedwith careful measurements, leads tosomewhat different conclusions.

InductanceRadial lead electrolytics areassembled with their connecting tabsattached towards the centre of theiranode and cathode foils. Woundtogether this produces a near non -inductive winding. The maincontribution to the capacitor's selfinductance then comes from theconnecting lead wires and tabs andnot the wound element.4

This is quickly proved. The largest

capacitor I measured for distortion,the Nitai 2201AF 63 volt bi-polar, hasa case size 25x16mm. I mounted oneon a test jig and measured its self -resonant frequency. It was 250kHz,well above audible.5

Polar & bi-polar electrolyticsIn my last article we saw that everypolar aluminium electrolyticcapacitor comprises two polarcapacitors in series, back to back.1Wound with an anode and cathodefoil, each foil with the electrolyte,comprises one capacitor. Thecathode foil provides a larger

Figure 2: The higher power 100Hz test system. Four BNCconnectors are arranged to accept Hewlett Packard testfixtures. The DC bias network inserts between the bufferamplifier and test fixture.

ET(E2u; CO Plot Top -40 00 Plot Range. 120 0

x

-40.0

-50.0

-60M,

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-00M,

03to -110.0'

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Left Channel

-0.08 dBV rrns

F,:17 -71r

J.

4

A

p.12 ciE j

crir

0.05162 °A)

SL_

100 200 300Frequency (Hz)

400 500 600 700

Oyerlays

8JrIjr Tantalum2.11 No Bias

100R@0.3

Figure 3: Distortion of this tantalum capacitor, ten times more than found with aluminium electrolyticcapacitors, does reduce slightly with DC bias.

January 2003 ELECTRONICS WORLD 45

COMPONENTS

Formed v Vr

SelfInductance

Figure 5: Thelowest distorting100pF 25 voltpolar capacitor ofthose tested, at 1volt. It should becompared withFigure 7 of mylast article. Bothcapacitorsproduced similarsecondharmonics. Thirdharmonic of the100pF hasincreased by4.5dB.

Series RCapacitance

IR of Anode

Anode Foil.

I. Sv Vr

Electrolyte/Paper

Series Rmuch largerCapacitance--VW--

IR of Cathode

Cathode Foil.

Figure 4: Simplified equivalent schematic shows how a polar electrolyticcapacitor behaves with AC signals, with and without DC bias.

capacitance, lower working voltage,than the anode foil.

With no bias voltage, the capacitorproduced predominantly secondharmonic distortion. In someinstances, application of a smalloptimum DC bias did minimise thissecond harmonic. Increased bias,however, resulted in increasedsecond harmonic distortion. For the100µF 25 volt capacitors tested,optimum bias varied by capacitor,from 1.1 to 4.2 volts.

Bi-polar capacitorsA bi-polar electrolytic is made inexactly the same way as a polar

capacitor, with one difference, inplace of the unformed cathode foil asecond, formed, anode foil is used.We still have two polar capacitancesin series, back to back, both now thesame value and voltage. To make thedesired value, two anode foils ofdouble capacitance are used.

Aluminium electrolytic capacitordesigners are accustomed to mixingand matching their availablematerials, to suit the capacitor's endapplication. So it should come as nosurprise that some designs are semibi-polar, i.e. they are made using alower voltage deliberately 'formed'anode foil as cathode.

Spectrum

121ilkid Doll CM Plot Top

-40.0

-50.0

-60.0

-70.0

-80.0

-90.0

-100.0

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100

0.56 dBV rms

-40.00

Lefl Channel

Plot Range 1200 lj

200 300 400Frequency (Hz)

overim

JrX 8

Silmic 51Jr Ov Bias

2_111-10R@1v

Using this constructionalbackground, we deduced an equivalentcircuit for a polar aluminiumelectrolytic capacitor. Fig. 4.

Dielectric OxideAluminium oxide has a `le of eight,similar to that of COG ceramics orsome impregnated paper capacitors.6It is higher than PET, which at 3.3,has the highest 1' of commonlyused film dielectrics. It is a lowvalue compared to the 'lc' of somethousands, found in 'high k' X7Rand Z5U ceramics.

More significant, though, isdielectric thickness. Aluminiumelectrolytic dielectric is muchthinner than that used in othercapacitors and the dielectric oxidefilm has a small but easily measuredvoltage coefficient of capacitance,typically +0.1% with +18v DC bias,but this is overshadowed many timesby its much larger dielectricabsorption. An electrolytic capacitoris exceptionally sensitive todielectric absorption effects and theapplied AC and DC voltages.

When our li.tF 63 volt polarelectrolytic was tested using two 0.7volt frequencies, its third harmonicwas -110dB or 0.0003%. It createdvisible intermodulation distortion.We also noted small capacitors ratedat 40 to 63 volt exhibiting nearoptimum quality.' Many 100µFcapacitors will be made with lowervoltage, thinner dielectric oxide,anode foil. This capacitance requireslengthy anode and cathode foils,housed in a larger diameter can. Togenerate the test voltage across thecapacitor, increased current mustpass through the tab connections intothe winding, amplifying the affectsof any non-linear resistance. It seemsprobable that similar harmonic andintermodulation levels will be foundat smaller test voltages.

To allow direct comparisonbetween the low cost 1µF 63 voltpolar capacitor and the physicallylarger Elna Silmic 100µF 25 volt, Ishow its distortions measured at

Distortion with voltage

We have seen how the test voltage used influences various capacitors.With sufficient test signal, most film and all electrolytic capacitorsdistort. It is prudent in any audio design to minimise the level of ACsignals which are developed across any capacitor.

At low frequencies this becomes difficult and may force a trade offbetween capacitor size and distortion. Equally important is the levelof DC bias voltage the capacitor must sustain. If more than a fewvolts, then for low distortion a low dielectric absorption material isessential. Because distortion results from non-linearities inside thecapacitor, inevitably it increases disproportionately both with

capacitance value and applied voltage.The change in amplitude of the second harmonic, when tested at a

constant signal with and without DC bias, clearly results from the DCbias voltage used, dielectric absorption and dielectric thickness.

Regardless of capacitance value, to minimise second and thirdharmonic distortions with increased AC and DC voltages, such asfound in valve amplifiers, then a foil and Polystyrene, foil andPolypropylene or double metallised foil, two -series, MKPPolypropylene capacitor, should be used.

46 ELECTRONICS WORLD January 2003

COMPONENTS

1 volt. This capacitor provided the best1 volt, no bias, results of the 10011Fpolar types in this article. Fig. 5.

Lower voltage measurementsAccurate 100Hz distortionmeasurements using test signalssmaller than 1 volt become quitedifficult, for two main reasons.1) Supply mains harmonics intrude

everywhere and are difficult toreduce using a computer basedsystem.

2) Inevitably, the smaller test signalreduces the dynamic range of ourmeasurement, dramaticallyinflating indicated distortion.

For example, using a 0.1 volt testsignal, my noise floor is around -112dB, hence a perfect capacitorproducing no distortion at all will stillregister some 0.0005%. However, ifwe compare the measured harmoniclevels of our electrolytic with thosefound for the identical measurementusing a metallised film capacitor, wewill see any increase in distortioncaused by the electrolytic capacitor.

To distinguish between harmonicsfrom the mains and the test capacitor,my test frequency was displaced a fewHz away from 100Hz. The Spectrasoftware then ignores mainsharmonics when calculatingdistortions. To assist visualidentification, I used frequencymarkers to identify mains harmonicsand amplitude markers to indicate thefirst four harmonics from the testcapacitor.

At 10010, a metallisedPolypropylene capacitor is both largeand costly. I used an assembly of10µF Evox Rifa MMK metallisedPET capacitors. This works well forsmall test voltages as a low distortion`reference' capacitor. Fig. 6.

Electrolytic distortionAs I've said before, despite somemarketing claims, capacitors are notcategorised for distortion, so adistorting capacitor would not beconsidered defective by its maker. Itis the responsibility of the equipmentdesigner to select the correctcapacitor for each circuit.

During this investigation Imeasured many other polarelectrolytics, rated from 10 to 100volt and capacitance to 220µF,produced by major manufacturers.To illustrate this article, I decided tomeasure three quite different 100µF25 volt polar electrolytic capacitorsand my PET assembly. I tested thelow cost Rubycon YXF, the largermore expensive Elna Silmic and theconsiderably more expensive BlackGate FK.

El Spectrum

Th

-40 0

-50 0

-60 0

-7001

-80 0 ,1

-900'.

E -100 0

co-0 -110 0

-120 0

Plot Top:

200

-40 00

Left Channel

Plot Range

300Frequency (Hz)

120 0

400 500 600 700

Overlays

2f 1 PET

Jr Ov Bias4J(-10R@0 .5vOptions

Figure 6: Distortion plot of an assembly of ten Evox Rifa 10pF 63 volt MMK metallised PET capacitors,tested at 0.5 volt. This 100pF assembly was used as the distortion reference for each test.

Ej Spectrum

ILK (3'.1 r:1 Plot Top -40 00 Plot Range 120.0

ea

-40.0

-50 0

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-o -110.0

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-160.014L

100

Len Channel

200 300 400Frequency (Hz)

Overlays

Figure 7: Distortion of a low cost, very small Rubycon YXF capacitor, tested at 0.1 volt with 18 voltDC bias, was less than 50% worse than the two larger, more expensive capacitors.

The Black Gate FK is a 21x lOmmsemi bi-polar, built using a lowvoltage anode as its cathode foil.The Silmic is 17x10mm and uses aspecial separator paperincorporating silk extracts. Bothwere purchased from AudiocomUK. The Rubycon YXF is a12x6.5mm conventional, miniature,low ESR low cost capacitorpurchased from Farnell.

Tests were performed using 0.1volt AC to 0.5 volt AC in 0.1 voltsteps, each using DC bias voltages of0 volt, 6 volt, 12 volt and 18 volt, atotal of 64 separate distortionmeasurements.

100pF 25 volt testsWith the 0.1 volt test signal, themeasurement noise floor wasreduced to -112dB. With no bias,distortions for the PET referencecapacitor and the Black Gate FKwere lost in noise. Second harmonicfor the Silmic measured -106.1dBand the YXF measured -102.8dB

With 18 volt DC bias, secondharmonic for all three electrolyticcapacitors increased to between -90and -94dB, distortions measuredsome three times greater than thePET assembly. Fig. 7

Using a 0.2 volt test signal, thenoise floor improved to -118dB.

January 2003 ELECTRONICS WORLD 47

COMPONENTS

Plot Top: -40.00 1 Range: 120.0

-40 0 -

-50.01

-60.0

-70.0,

-80 0

-90.0

E-1000

--0-110.0±

-120.0

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pert Channel

0 12 dBV rms

.- Overton_.

IIY 3.140

0.00064 %

73 381

r, 1456 110ff" °"-

4

100 200 300Frequency (Hz)

460 500 600 700

A 8Jr111- Silmic3f r Ov Bias4f r lOR 0.2v

Figure 8: The 100pF 25 volt Silmic capacitor of Figure 5, tested at 0.2 volt. With no bias, secondharmonic is 6dB smaller and distortion little more than half that of the more expensive Black Gate FK.

With and without bias, allelectrolytic distortions increasedmore than the change of test signal.With no bias the Silmic performedbest of the three electrolytics,outperforming the Black Gate FK byalmost 6dB. Fig. 8.

With 18 volts DC bias, dielectricabsorption effects increased thesecond harmonic of the Silmic by21.7dB and it's distortion to0.0054%. The Black Gate was lessaffected and its distortion increasedto 0.0037%. The YXF distortedrather more, at 0.0063%. Third

harmonic distortions were visibleabove the noise floor, but notsufficient enough to producemeasurable intermodulationdistortion.

With a 0.3 volt test signal, themeasurement noise floor improvedto -123dB but the PET referencecapacitor harmonics remain buried innoise. Second and third harmonics ofthe polar capacitors are now clearlyvisible, their distortions havingincreased much faster than the testsignal level.

With a 0.3 volt test signal and no

bias, the Silmic, at 0.00098%,produced the least distortion of thethree electrolytics. Its secondharmonic measured -100.6dB, theBlack Gate -98.5dB and the YXF -89.1dB. The best electrolytic producedmore than three times the distortion ofthe PET assembly. Fig. 9.

With a 6 volt DC bias, the Silmicand Black Gate, with secondharmonics around -90dB, producedsimilar 0.003% distortion. The YXFsecond harmonic was -87.3dB for0.0043% distortion.

With 18 volt DC bias the BlackGate develops fifteen times moredistortion than the PET assembly butdistorts less than the other twoelectrolytics. Its second harmonic at-84.1dB was some 3dB better thanthe Silmic and 4dB better than thelow cost YXF type. Distortions nowmeasured 0.00637%, 0.00840% and0.00951% respectively.Fig. 9B.

Third harmonics for all threeelectrolytics have reached the levelfor measurable intermodulation,which was confirmed by more tests,using 18Hz as the second frequency.

All three electrolytics producedsignificant distortions in this 0.3 volttest. Almost five times larger withno bias, at least fifteen times largerwith bias, than my PET assembly. Iconsider distortions from these1000' polar capacitors tested at 0.3volt, exceed the sensible limit foruse in the signal path of high qualityaudio.

Some writers advocate using a low

100 Hz test equipment

The oscillator and notch filter/preamplifier printed boards can be usedat other frequencies by scaling the values of a few capacitors.2

Oscillator boardFor 100Hz, use 100nF 1% metallised Polypropylene for Cl, C2, and C3.Bypass R16 by a wire link. To differentiate between test capacitor and mainsfrequency harmonics, replace R23, R24 and R25 with wire links.

Twin -Tee notch filter/pre-amplifier boardFor 100Hz, use 100nF 1% metallised Polypropylene for C41, C42, C43,C44, C47 and C48. Use 47nF 1% metallised Polypropylene for C45and C46. Use 10nF 1% metallised Polypropylene for C49.

Output Buffer.At 100Hz, 10pF capacitors can be tested to 5 volts, using the AD811output buffer amplifier described.3 Adding a 10 Ohm current limitingresistor allows 100pF to be tested to 0.5 volts.

To fully test 100pF capacitors, a higher power buffer amplifier isneeded. It should develop at least 5 volts signal across a 100pFcapacitor via a 1052 current limiting resistor.

I have designed a buffer amplifier and printed circuit board, able todrive up to 7 volts or 400mA, with extremely low distortion. An ElantecEL2099CT output amplifier is used with an input buffer. This can be anOP295, OPA2134 or an NE 5532A, by connecting one link. I used an

OPA2134 in my prototype. Fig. 1

Larger decoupling capacitors are used with 1.5 Amp stabilisers. APerancea 75 by 50mm PCB case serves as heat sink for the EL2099CTand the stabilisers.

Apart from these changes, the buffer amplifier schematic circuit andthe current limiting resistors/switch follow the approach previously usedfor my lkHz AD811 output buffer.

When testing 100pF, a four wire test method should be used. FourBNC connectors, two to output the test current and two to measure thecapacitor distortions, are spaced at 22mm centres to fit Hewlett Packardcapacitor test jigs. Alternatively, four discrete BNC cables and crocodileclips can be used.

To measure capacitors larger than 10pF with DC bias voltage, a DCblocking buffer circuit as already described but made with largercapacitors is essential.

Two 50pF 450 volt metallised Polypropylene motor run capacitorsreplaced the 11 pF current carrying capacitors of my 1 kHz design. Three3.3pF MKP capacitors provide 10pF for the voltage measuring circuit.These components were mounted in a die-cast box and hardwired.

Four BNC connectors were mounted on opposite sides of this box, tomate with my 100Hz output buffer amplifier and the Hewlett Packardcapacitor test jigs. Fig. 2

A selectable DC bias voltage was provided, by mounting 20 AA cellsand a range switch, in a second die cast box. This was used with bothDC blocking buffer designs.

48 ELECTRONICS WORLD January 2003 ".

COMPONENTS

di

distortion film capacitor in parallelwith an electrolytic, to reducedistortion. Does it work?

Using a film shuntTo find out, I made a fewmeasurements on these capacitorsusing a 1 volt test signal, unbiasedthen with 18 volt DC bias. As ashunt I used my low distortion li.tFMKP and also a 100 bank of three3.3g low distortion metallised PPScapacitors.

With 10 shunt, second and thirdharmonics of the Silmic reduced byjust 1dB. Using the 10itF, bothharmonics reduced by a further 1dB.This small reduction is not worth the

Technical Support

Interested readers are free to build asystem for personal use oreducational use in schools andcolleges. Commercial users andreplicators should first contact theauthor.

A professionally produced set ofthree FR4 printed circuit boards,with solder resist and legends, forthe 1 kHz signal generator, outputbuffer amplifier/notch filter/pre-amplifier and the DC bias buffernetwork, comprising a 'with DCbias, single frequency, distortion testsystem', complete with heat boundhardcopy 28 pages A4 assemblynotes, parts lists and drawings andwith PCB's costs £32.50.

To reduce your costs, I now offerPCB's with the 28 page assemblynotes, parts list and PCB drawings,as PDF files on floppy disc, for £30.

If ordered at the same time aseither of the above, additional setsof PCBs cost £27.50, but pleasedouble the post/packing costs.

The CD ROM with 28 pagemanual, parts lists, PCB drawings,added distortion measurementresults and even more capacitorinformation but no PCBs, costs £15

Post/packing to UK address £2.50.Post/packing to EU address £3.50,rest of world £5.50.

As a service to non -UK readers, ifordered with the above PCBs, a fourgang potentiometer, re -tinned andtested, with each set of boards, costsan additional £5.00 inclusive ofpostage.

Falcon Electronics te1:01508578272 (EW September) has thesepotentiometers in stock.

Postal Orders or Cheques, forpounds sterling only, to C. Bateman.'Nimrod' New Road. ACLE.Norfolk, NR13 3BD, England.

additional PCB space and extra cost,because even with a 100 shunt,distortions far exceed those of mymetallised PET assembly.

Perhaps a higher voltage capacitorwould measure better, or would itslonger anode and cathode foilssimply make matters worse?

100pF 50 volt testsExamination of my earlier distortionplots suggested the only suitable1000 electrolytic types I had whichmight measure lower distortion werethe 22x12.5mm 50 volt Silmic andthe 26x12.5mm 50 volt Panasonic Sbi-polar, Farrell 218-698. With a 0.3volt test signal and no bias, the 50

volt Silmic distorted more than the25 volt version. Because of its muchlonger foils, the second harmonicincreased 2dB, the third, 7dB anddistortion measured 0.00134%.Fig. 10.

Due to the thicker dielectric usedfor the 50 volt capacitor, with 18volt DC bias, the second harmonicincreased less, now almost 6dBsmaller than the 25 volt version.Distortion at 0.00460% was just overhalf that of the 25 volt version.

Bi-polar testsThe Panasonic S bi-polar capacitorat 0.3 volt with no bias produced lessthan half the distortion of the 25 volt

Spectrum

-40.0

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rx

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Lk Plot Top: 1-40 00 Plot Range:

300Frequency (Hz)

1200

ea x

Overlays

_U8r2j r. B.Gate FK,1.Jr ON, Bias2ljr 1OR @ 0.3y

Figure 9: Tested at 0.3 volt with no bias, the 100pF 25 volt Silmic produced the smallest secondharmonic, 2dB better than the Black Gate FK shown and 11d8 better than YXF. Third harmonic was -112.8dB Silmic, -110.5d8 for YXF.

EA. Spectrum

1:1-40.0

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.0-110.0

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117 Li M.1"IA_ Plot Top: -40 00

Left Channel

Plot Range. 120.0

200 300 400 500 600 700Frequency (Hz)

Figure 98: As Figure 9 with 18 volt DC bias, the Black Gate FK second harmonic increased 14.4dB,distortion is now 3dB smaller than the Silmic but fifteen times bigger than the PET assembly.

nM January 2003 ELECTRONICS WORLD 49

COMPONENTS

Spectrum

NAJD-40.0

-50.0

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Plot Range:

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0.00 1 34 %

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voisworePRIP50 dB

400 500 600 700

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8r2j r Silmic #13f r Ov Biasit 1oR@0.35

Options. j

Figure 10: Tested as Figure 9, this 100pF 50 volt Silmic shows 2dB more second harmonic and 7dBhigher third harmonic. Its longer foil lengths produced a 35% increase in distortion.

40 0

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v-1100

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100 200 300FiequencY (q7)

400 500 600 760

c C31

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Options

Figure 11: Tested as Figure 9, this 100pF 50 volt Panasonic bi-polar measured just 0.00042%, less thanhalf the distortion of the best polar capacitor.

Silmic. The second harmonicmeasured -111.8dB, the third -119.6dB and distortion was0.00042%. With an 18 volt DC bias,the second harmonic increased to -92.7dB and distortion to 0.00237%,that's half the distortion of the 50volt Silmic.

The Panasonic S bi-polar producedthe lowest distortion of all single100g electrolytic capacitors I tested,using a 0.3 volt signal and DC biasfrom 0 volt to 18 volts.Fig. 11.

In my last article we saw howusing two polar capacitors in seriescould reduce distortion. Let usexplore using two bi-polar capacitorsin series.

Two better than one?I already had some 2200 63 voltNitai bi-polar electrolytics, Farnell317-4906. Two connected togetherin series would approximate 100p.F.

Measured at 0.3 volts with no bias,the second harmonic level wasreduced by 6dB compared to thePanasonic S bi-polar. With thesecond and third harmonics buried inthe noise floor, distortion at0.00033% measured the same as thePET assembly. With 18 volt DCbias, second harmonic measured -105.3dB and distortion 0.00063%. Anear four -fold improvementcompared to the Panasonic S bi-polar, more than seven times better

than the best polar capacitor tested.To better compare harmonics we

examined performances using a 0.5volt signal. With no bias, those formy PET assembly can just be seenemerging from noise. The secondharmonic was at -124.3dB, the third-123.9dB and distortion was0.00020%. Fig. 6.

The double 220µF 63 volt bi-polarsecond harmonic was -117.7dB, thethird -124.1dB and distortion was0.00023%, practically the samedistortion as the PET assembly.Fig.1 2.

With 18 volt DC bias, the secondharmonic of the double bi-polarincreased to -100.7dB and distortionto 0.00093%, slightly more thandouble the distortion measured onthe PET assembly with this bias.

This is an excellent performancefrom electrolytic capacitors, but howdoes this series pair of bi-polarcapacitors stack up for size and cost?Can this bi-polar series pair producelow distortion with a 1 volt signal?

Double bi-polar v alternativesThe series pair requires less PCBarea, is lower cost and dramaticallyoutperforms a polar capacitor with afilm shunt.

At 1 volt with no bias, the noisefloor improved to -132dB. Distortionof the PET assembly measured0.00011%, a single Panasonic S bi-polar 0.00054% and the Silmic 25vwith 10p.F shunt 0.00151%. The2201.tF 63 volt Nitai series pairmeasured 0.00016%, practicallyequalling that measured on the PETassembly, ten times less distortionthan the Silmic capacitor.

With an 18 volt DC bias, the220pf 63 volt Nitai series pairdistortion measured 0.00217%.Slightly more than six times that ofthe PET assembly but nearly seventimes less distortion than using the50 volt Silmic polar capacitor. Thisseries pair of 220µF 63 volt Nitai bi-polar capacitors costs one eighth andtakes just one fifth the PCB area ofmy PET assembly. To explore otherdouble bi-polar options, I purchased35 volt and 16 volt 2201.1F Nitai bi-polar capacitors for tests.

Smaller, doubled bi-polarWith no bias and tested at 0.5 volt,distortion for all three voltage bi-polar doubles measured almost thesame as the PET assembly, but 18volt DC bias revealed largedifferences. The 16 volt series pairmeasured 0.00693%, the 35 voltseries pair 0.00230% and the 63 voltseries pair 0.00093%.

For the lowest possible distortion

50 ELECTRONICS WORLD January 2003 MI

COMPONENTS

when DC blocking/signal coupling, Isuggest the 16 volt pair is only usedwith negligible DC bias, the 35 voltpair be used to say 6 volt bias andthe 63 volt pair to say 12 - 15 voltsbias. With such small DC voltages,no voltage sharing resistors areneeded.

Used in a 'Long Tailed Pair'amplifier feedback network to ensureunity gain at DC, the 63 volt seriespair could be used with supply railsup to 63 volts, without voltagesharing resistors. For higher voltagesuse a series pair of 100 volt bi-polar.

This 63 volt series pair can alsobenefit local supply rail decoupling,but for this use, voltage sharingresistors, passing a few milliampsfrom the supply to the capacitorscentral connection and ground, mustbe used.

ConclusionsHaving measured a considerablenumber of aluminium electrolyticsusing test voltages from 0.1 volt to 3volt, with and without bias, a singlebi-polar type produced lowerdistortion than larger, moreexpensive, specialist polarcapacitors.

Much better results were obtainedby connecting two double value bi-polar electrolytics in series. Using 1volt or smaller test voltages and nobias, distortions for a double bi-polarand the metallised PET assemblywere similar.

With increasing bias or withincreasing test voltage, themetallised PET assembly producedless distortion than any electrolytic Itested.

100pF choiceProvided the AC voltage developedacross the capacitor at the lowestaudio frequencies is 1 volt or lessand no significant DC bias is used, adouble bi-polar series pair providesan economic solution.

When higher AC signal voltages,especially combined with significantDC bias, must be applied, themetallised PET combinationproduces less distortion. It costseight times more and takes fivetimes more PCB area than the doublebi-polar.

For the least practical distortion,an assembly of metallisedPolyphenylene Sulphide capacitorsmight be feasible. It needs doublethe board area and is five times moreexpensive than the PET assembly.

For small AC signals with modestDC bias and for supply raildecoupling, I choose the double bi-polar 63 volt solution.

LiSpecItum

11); gui Li_ Plot Top: -40 00 Plot Range 120u

x

-40.0

-50.0

-60.0

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-90.0

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-1600

Left Channel

300Frequency (Hz)

Overlays

8r2.1 r- Nitai BPJf Os BiasAir loR o.5v

Figure 12: A series pair of 220pF 63 volt Nitai bi-polar capacitors with 0.5 volt test signal. With no biasdistortion was similar to my metallised PET assembly, five times smaller than the best polar capacitortested. With 18 volt DC bias, 0.00093% distortion is nine times smaller than the best polar capacitor.

ESR/tano

The most nearly perfect capacitor wouldexhibit near zero ESR. Low ESR is essentialfor use in switched mode power supplies,but does a low ESR electrolytic ensure lowaudio distortion?

Of the 100pF capacitors I tested, the 10volt Oscon measured the lowest 100kHzESR of all, 0.012 Ohms and 100Hz tanb of0.035. It would be unreasonable tocompare a 10 volt capacitor with highervoltage types so I also measured 10 voltRubycon YXF and Elna RSH types. The YXF

ESR measured 0.550 Ohms and tan8 0.091.The RSH ESR was similar, at 0.505 Ohmsand tanb at 0.104.

Tested at 0.5 volt with and without 6 voltsDC bias, the Rubycon YXF produced theleast distortion, 0.0351% with DC bias and0.00331% unbiased. The Oscon distortedworst of the three, measuring 0.05321%with DC bias and 0.02499% unbiased.

Clearly low tano at 100Hz and low ESR at100kHz does not ensure low audiodistortion.

10pF choice.We have three possibilities. Adouble bi-polar using two 22IAF50/63 volt bi-polar electrolytics, a101,11F metallised PET or an assemblyof three 3.31iF PPS capacitors.

The lowest cost solution for usewith signal voltages less than 1 voltand no significant bias is a doublebi-polar series pair. A 101AF MMKmetallised PET takes the same PCBarea and distorts less with DC bias.

The PPS capacitor assemblyensures lower distortion, especiallywhen used with increased ACsignals or DC bias voltage. Howeverit occupies more board area and isexpensive.

An assembly of Polypropylenecapacitors, as used in the DC biasnetwork, would provide the lowestpossible distortion, but requires afive times larger board area and ismost expensive.

For small AC signals and modest

DC bias, I choose the 1011F MMKmetallised PET capacitor.

References.1. Capacitor Sound part 5 C.

Bateman EW December 2002p.44

2. Capacitor Sound? C. BatemanElectronics World July 2002 p.12

3. Capacitor Sound 2 C. BatemanElectronics World September2002 p.16

4. Understanding capacitors -aluminium and tantalumElectronics World June 1998p.495. C. Bateman

5. Evaluate capacitors for SMPSdesigns. C. BatemanElectronics World Sept 2000p.696

6. Reference Data for RadioEngineers. Howard Sams & Co.Inc. New York

Certain aspectsof this article arethe subject of apatentapplication.

January 2003 ELECTRONICS WORLD 51

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imoElectronics World reader offer:xl, x10 switchableoscilloscope probes,only £21.74 a pair,fully inclusive**Additional pairs as part of the same order, only219.24 each pair.

Please supply the following:

Probes

Name

Address

Total

Postcode Telephone

Method of payment (please circle)

Cheques should be made payable to ELECTRONICS WORLD

Access/Mastercard/Visa/Cheque/PO

Credit card no

Card expiry date Signed

Please allow up to 28 days for delivery

Seen on sale for £20 each, these high -quality oscilloscope probe sets comprise:

two xl, x10 switchable probe bodies two insulating tips two IC tips and two sprung hooks trimming tools

There's also two BNC adaptors for using thecables as 1.5m -long BNC-to-BNC links.

Each probe has its own storage wallet.To order your pair of probes, send the

coupon together with £21.74 UK/Europe toProbe Offer, Jackie Lowe, HighburyBusiness Communications, AnneBoleyn House, 9-13 Ewell Road,Cheam, Surrey, SM3 8BZ

Readers outside Europe, please add

£2.50 to your order.

Specifications

Switch position 1BandwidthInput resistanceInput capacitanceWorking voltage

Switch position 2BandwidthRise timeInput resistance1MS1Input capacitanceCompensation rangeWorking voltage

DC to 10MHz1 MQ - i.e. oscilloscope i/p40pF+oscilloscope capacitance600V DC or pk-pk AC

DC to 150MHz2.4ns10MQ ±1% if oscilloscope i/p is

12pF if oscilloscope i/p is 20pF10-60pF600V DC or pk-pk AC

Switch position 'Ref'Probe tip grounded via 9MQ, scope i/p grounded

AO

M teragel

WATCH SLIDES ON TVMAKE VIDEOS OFYOUR SLIDESDIGITISE YOURSLIDES(using a video capture card)

"Liesgang diatv" automatic slide viewer with built in high quality colour TV camera. It hasa composite video output to a phono plug (SCART & BNC adaptors are available). Theyare in very good condition with few signs of use. For further details see www.diatv.co.uk

£91.91+ vat = £108.00Board cameras all with 512x582 pixels 8.5mm 1/3 inch sensor and composite video out.All need to be housed in your own enclosure and have fragile exposed surface mountparts. They all require a power supply of between 10 and 12v DC 150mA.47MIR size 60x36x27mm with 6 infra red LEDs (gives the same illumination as a smalltorch but is not visible to the human eye) £37.00 + vat = £43.4830MP size 32x32x14mm spy camera with a fixed focus pin hole lens for hiding behind avery small hole £35.00 + vat = £41.1340MC size 39x38x27mm camera for 'a mount lens these give a much sharper imagethan with the smaller lenses £32.00 + vat = £37.60Economy C mount lenses all fixed focus & fixed irisVSL122OF 12mm F1.6 12x15 degrees viewing angle £15.97 + vat = £18.76VSL4022F 4mm F1.22 63x47 degrees viewing angle £17.65 + vat = £20.74VSL6022F 6mm F1.22 42x32 degrees viewing angle £19.05 + vat = £22.38VSL8020F 8mm F1.22 32x24 degrees viewing angle £19.90 + vat = £23.38Better quality C Mount lenses

VSL1614F 16mm F1.6 30x24 degrees viewing angle £26.43 + vat = £31.06VWL813M 8mm F1.3 with iris 56x42 degrees viewing angle... £77.45 + vat = £91.001206 surface mount resistors E12 values 10 ohm to 1M ohm 100 of 1 value £1.00 + vat1000 of 1 value £5.00 + vat

866 battery pack originally intended to be used with an orbitelmobile telephone it contains 10 1.6Ah sub C batteries(42x22dia the size usually used in cordless screwdrivers etc.)the pack is new and unused and can be broken open quiteeasily £7.46+vat = £8.77

Please add 1.66 + vat = £1 .95 postage & packing per order

JPG ELECTRONICSShaws Row, Old Road, Chesterfield, S40 2RB

Tel 01246 211202 Fax 01246 550959 MastercardNisa/SwitchCallers welcome 9:30 a.m .to 5:30 p.m. Monday to Saturday

The Stereo Headphone Amplifier BoxBalanced or unbalanced line inputs to stereo

headphone outputProfessional portable units operating from an internal PP3

battery or external mains adaptor

* Precision transformerless differential left and right inputs *Wide range of headphone drive impedances * High commonmode rejection * Low noise and distortion * Low quiescent

power consumption for extended battery life * Extensive RFIprotection

The Balance Box (mic/line amplifier) - The PhantomPower Box - The OneStop DIN rail mounting radio frequencyinterference filter and voltage transient protector for voltage and

current loop process signal lines

Conford Electronics Conford Liphood Hants GU30 7QWInformation line 01428 751 469 Fax 751223

E-mail: contact@confordelec.co.ukWeb http://www.confordelec.co.uk/

SPECIAL OFFERS

1-77.77 V V - =

TEKTRONIX 2445A 4 Ch ONLY150MHz Delay, Cursors etc.Supplied with 2 Tektronix probes <MO

TEKTRONIX 2232 Digital Storage Scope. Dual Trace100 MHz,100m/s with probes. £525H.P. 54501A Digitizing Oscilloscope100MHz, 4Ch £425H.P. 3312A Function Gen 0.1Hz-13MHz AM/FMSweep/Tri/Gate/Burst etc £300FARNELL Dual PSU XA35-2T 0-35V 0-2A Twice OMDLCD Display £180CIRRUS CRL254 Sound Level Meter with Calibrator,80-120dB, LEO £150EDDYSTONE 1002 Receiver 150kHz-30MHz r BroadcastFM £125FARNELL AMM255 Automatic Mod Meter 1.5MHz-2GHz Unused £300FARNELL DSG1 Low Frequency Syn Sig Gen0.001Hz to 99.99kHz, Low Distortion TTUSquare/Pulse Outputs etc £95FLUKE 8060A Handheld True RMS OMM 41/2 digit

As new £150. Used £95BECKMAN HD110 Handheld 31/, digit DMM, 28 rangeswith battery, leads and carryin case £40

H.P. 3310A Function Gen 0.005Hz-5MHz Sine/Sq/Tri/Ramp/Pulse £125FARNELL FLM4 Sine/Sg Oscillator 10Hz-1MHz lowdistortion. TTL Output. Amplitude Meter £125H.P. 545A Logic Probe with 546A Logic Pulserand 547A Current Tracer £90FLUKE 77 Multimeter 31/2 digit Handheld £60FLUKE 77 SERIES II £70HEME 1000 LCD Clamp Meter 0-1000A. In CarryingCase £60

MARCONI 2019A, TEMETEMZEI

AM/FM synthesised signalgenerator 80kHz - 1040MHz

NOW ONLY £400MARCONI 893C AF Power Meter, Sinad Measurement

Unused £100 Used £60MARCONI 8938 - No Sinad £30MARCONI 2610 True RMS Voltmeter Autorangin 5Hz-25MHz £195GOULD J3B Sine/Sq Osc. 10Hz-100kHz. Low distortion

£75-£125AVO 8 Mk6 in Ever Ready Case, with leads etc £80Others Avos from £50GOODWILL GVT427 Dual Ch AC Millivoltmeter 10mV in 12Ranges Freq 10Hz-1MHz 2100-£125SOLARTRON 7150 DMM 61/2 digit True RMS IEEE

£95-£150SOLARTRON 7150 PLUS £200

HIGH QUALITY RACAL COUNTERS9904 Universal Timer Counter, 50MHz £509916 Counter, 10Hz-520MHz £759916 Counter, 10Hz-560MHz 9 -digit £50WAYNE KERR 6424 Component Bridge £125RACAUAIM 9343M, LCR Databridge, Digital £200Automeasurements of R.C.L.Q.D.HUNTRON TRACKER Model 1000 £125MARCONI TF2015 AM/FM sig gen, 10-520MHz £175FLUKE 8050A 4.5 Digit, 2A True RMS £75FLUKE 8012A 3.5 Digit, 2A £40

SOLARTRON 7045 Bench Multimeter4.5 Digit Bright LED with Leads ONLY £30

Racal 9008 ONLY AM. Portable Appliance TesterAutomatic Modulation Meter AM/F1.5MHz - 2GHz

Megger Pat 2 ONLY

Outran 1061High Quality 5.5 Digit Bench MultimeterTrue RMS/4 wire Res/Current Converter/IEEE

£150

Datron 1061AHigh Quality 616 digit Bench MuttimeteTrue RMS/4 wire/Current Converter

Racal Receiver RA177250KHz - 30MHzLED Display. Basically Working.

£250

£180

H.P. 60120 DC PSU 0-60V; 0-50A 1000W £1000FARNELL AP60/50 1KW Autoranging £1000FARNELL H60-/50 0-60V 0-50A £750FARNELL H60/25 0-60V; 0-25A £400Power Supply HPS3010 0-30V; 0-10A £140FARNELL L30-2 0-30V; 0-2A £80FARNELL L30-1 0-30V; 0-1A £60Many other Power Supplies available.Isolating Transformer 240V In/Out 500VA £40

STEWART OF READING Immo110 WYKEHAM ROAD, READING, BERKS RG6 1PL vim

Telephone: (0118) 9268041 Fax: (0118) 9351696www.stewart-of-reading.co.uk

Callers welcome 9am-5.30pm Monday to Friday (other times by arrangement)

FARNELL DTV 12-14 OSCILLOSCOPEDUAL TRACE 12 MHz TV. COUPLING

ONLY 420)FARNELL LFI 12-14 SIne/Sq OCSILLATOR10 MHz -1 MHz

ONLY QED

OSCILLOSCOPESTEKTRONIX TDS350 Dual Trace 200MHz 1G/Sunused £1500TEKTRONIX TDS320 Dual Trace 100MHz 500M/S £1200TEKTRONIX TDS310 Dual Trace 50MHz 200M/S £950LECROY 9400A Dual Trace 175MHz SG/S £750HITACHI VC6523 Dual Trace 20MHz 20M/S etcunused £500PHILIPS PM3092 2r2Ch 200MHz Delay

£800 As New £950PHILIPS PM3082 2+2Ch 100MHz Delay etc

£700 As New £800TEKTRONIX TAS465 Dual Trace 100MHz Delay etc ..£750TEKTRONIX 24658 4Ch 400MHz Delay Cursors etc£1500TEKTRONIX 2465 4Ch 300MHz Delay Cursors etc....£900TEKTRONIX 468 Dig Storage Dual Trace 100MHzDelay £450TEKTRONIX 466 Analogue Storage Dual Trace100MHz £250TEKTRONIX 485 Dual Trace 350MHz Delay Sweep £550TEKTRONIX 475 Dual Trace 200MHz Delay Sweep £350TEKTRONIX 465B Dual Trace 100MHz Delay Sweep £325TEKTRONIX 2215 Dual Trace 60MHz Delay Sweep £250PHILIPS PM3217 Dual Trace 50MHz Delay ...£200 - £250GOULD 051100 Dual Trace 30MHz Delay £125HAMEG HM303.6 Dual Trace 35MHz ComponentTester. As new £240HAMEG HM303 Dual Trace 30MHz ComponentTester £200MANY OTHER OSCILLOSCOPES AVAILABLE

MARCONI 2022E Synthesised AM/FM Sig Gen.£525 - £75010KHz - 1.01GHz LCD Display etcH.P. 8657A Syn 100KHz - 1040MHz Sig Gen £2000H.P. 86560 Syn 100KHz 890MHz Sig Gen £1350H.P. 8656A Syn 100KHz - 990 MHz Sig Gen £995R&S APN62 Syn 1Hz - 260KHz Sig Gen £425Balanced/Unbalanced Output LCD DisplayPHILIPS PM5328 Sig Gen 100KHz - 180MHz with 200MHz

£550Freq Counter IEEERACAL 9081 Syn AM/FM Sig Gen 5KHz - 1024MHz .£250H.P. 3325A Syn Function Gen 21MHzMARCONI 6500 Amplitude Analyser £1500H.P. 4192A Impedence Analyser £5000H.P. 4275A LCR Meter 10KHz -10MHz £2750H.P. 8903A Distortion Analyser £1000WAYNE KERR Inductance Analyser 3245 £2000H.P. 8112A Pulse Generator 50MHz £1250MARCONI 2440 Freq Counter 20GHz £1000H.P. 5350B Freq Counter 20GHz £2000H.P. 5342A 10Hz - 18GHz Freq Counter £800H.P. 16508 Logic Analyser 80 Channel £1000MARCONI 2305 Mod Meter 500KHz - 2Ghz £750

RADIO COMMUNICATONS TEST SETSMARCONI 2955/2955A from £1500Rohde & Schwarz CMT 0.1 - 1000MHz £2000Schlumberger 4040 £900

JUST IN

H.P. 60638 DC Electronic Load 3-2400/0-10A 250WP.O.A.

H.P. 66312A PSU 0 - 20V/0 -2A £400H.P. 66311B PSU 0 - 15V/0 -3A £400H.P. 66309D PSU Dual 0 - 15V 0 -3A/0 -12V 0-1.5A £750H.P. 6632B PSU 0 - 20V/0 -5A £500H.P. 6623A PR Triple Output ranging from £8500-7V 0-5A to 0-20V 0-4AH.P./Agilent 34401A DMM 61/2 digit £400/£450H.P. 3478A DMM 51/2 digit £275FLUKE 45 DMM Dual Display £400KEITHLEY 2010 DMM 7112 digit £950KEITHLEY 617 Programmable Electrometer £1250H.P. 4338B Milliohmmeter £1500RACAL Counter type 1999 2.6 GHz £500H.P. Counter type 53131A 3GHz £850H.P./Agilent 33120A Function Gen/ARB £900/£1000100microHz - 15MHzSONY/TEKTRONIX AFG320 Arbitary Function Gen..£1250H.P. 8904A Syn Function Gen DC - 600KHz£1000/£1250BLACK STAR JUPITOR 2010 Function Gen 0.2Hz - 2MHzwith Frequency Counter £140H.P. 8116A Pulse Generator 1mH-50MHz £1950H.P. 86576 Syn Signal Gen 0.1-2080MHz £2500CO -AXIAL SWITCH 1.5GHz £40IEEE CABLES £10

11121=2:13111121H.P. 8561B 50Hz - 6.5GHz £5000H.P. 8560A 50Hz - 2.9GHz Synthesised £5000H.P. 8594E 9KHz - 2.9GHz £4500H.P. 8591E 1MHz - 1.8GHz 75 ohm £2750H.P. 853A with 8559A 100KHz - 21GHz £1750H.P. 85586 with Main Frame 100KHz - 1500MHz £750H.P. 3585A 20Hz - 40MHz £2500H.P. 3580A 5Hz - 50KHz £600ADVANTEST R41316 10KHz- 3.5GHz £2750EATON/Ailtech 757 0.001 - 22GHz £750MARCONI 2382 100Hz - 400MHz High Res £2000MARCONI 2370 30Hz - 110MHz from £500H.P. 182 with 8557 10KHz - 350MHz £500H.P. 141T Systems8553 1KHz - 110MHz £5008554 500KHz 1250MHz £7508555 10MHz - 18GHz £1000H.P. 8443 Tracking Gen/Counter 110MHz £250H.P. 8444 Opt 059 £750B & K 2033R Signal Analyser £650H.P. 8754A Network Analyser 4MHz - 1300MHz.....£1250H.P. 3577A Network Analyser 5Hz - 200MHz £3000H.P. 53310A Modulation Domain Analyser Opt001/003 £5000ONO SOKKI Portable FFT Analyser £1500H.P. 8720C Microwave Network Analyser 50MHz-20GHz

£12500

USED EQUIPMENT - GUARANTEED. Manuals supplied.This is a VERY SMALL SAMPLE OF STOCK. SAE or telephone for lists. Please check availability before

ordering. CARRIAGE all units £16. VAT to be added to total of goods and carriage.

January 2003 ELECTRONICS WORLD 55

MIN

As an advertiser you can be certain that your sales message isgoing to be read by decision -making electronics professionalswith the power to purchase your products.

The pre -paid rate for semi -display setting is £17 per single column centimetre(maximum 4cm). Box number £22 extra. All prices plus 1772°/. VAT.All cheques, postal orders etc to be made payable to Highbury BusinessCommunications Ltd. Advertisements together with remittance should be sentto Electronics World Classified, Highbury Business Communications Ltd,Anne Boleyn House, 9-13 Ewell Road, Cheam, Surrey SM3 8DZ.Tel: 020 8722 6028. Fax: 020 8770 2016.

ServiceLink

ARTICLES WANTED

BEST CASHPRICES PAID

For all valvesKT88 PX4 and

other audio types

Wide range ofvalves and CRT

stocked

Tel:01403 784961

Billington Export Ltd.Fax: 01403 783519

Email: sales@bel-tubes.co.ukSussex RH14 9EZ

Visitors by appointment

TOP PRICES PAIDFor all your valves,

tubes, semi Conductorsand ICs.

Langrex Supplies Limited1 Mayo Road, Croydon, Surrey CR0 20P

TEL: 020 8684 1166 FAX: 020 8684 3056

FOR SALE

PRINTED CIRCUIT BOARDSDESIGNED & MANUFACTURED Jun agar Prototype or production quantities Fast turnround available !!!!! Circuits PCBs designed from circuit diagrams Almost all computer files accepted PCB assembly - mechanical assembly Full product design-manufacture test-repair

Unit 5, East Belfast Enterprise Park308 Albertbridge Rd, Belfast BT5 4GX

TEL 028 9073 8897 FAX 028 9073 1802

info@agarcircuits.com

RF DESIGNSERVICESAll aspects of RF

hardware development

considered from

concept to production.

WATERBEACH ELECTRONICS

www.rlaver.dial.pipex.com

TEL: 01223 862550FAX: 01223 440853

ServiceLink

SERVICES

lik#C pt 48 HOUR

ProductionElectronic design and manufacturing services for the new millennium:

Embedded monitoring & control Wireless telemetry systems rnPSTN telephones and test equipment Audio & Video processingDatacom interfacing, line driving etc.Switch Mode & linear PSU and battery

GSM telemetry via, SMSor data (TCP/IP)

o=managementGas detection systems

DVD player control systemsGPS positioning systems

,T1

cry0 -cs

Printed Circuit Board design Specialist cable loomsTechnical documentation, schematiclayout & language translation

Small, medium & large scalemanufacturing

Email: sales@designersystems.co.ukTel/Fax: +44 (0) 1872 223306

DesignecV MICROCHIP * sx

E

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SERVICES

PCBs Conv/PTH/Multi.Layer/Flexible UK & Far East production

CAD Layout Electronic Design Assembly (prototype & production) SMD m/c assy Tct 18,500 cps/hr

Deliveries Item

24Hrs ram lust

£40.Tel: 01635 40347 -Newbury Electronics LtdFaraday Road Newbury Belts RG14 250

Fax. 01635 36143e-mail: circuitsnewbury.tcom.co.ukhttp.,/www.newburyelectronics.cosk

SEE OUR WEB SITES

visit

www.pcbtrain.cornThe low cost source for prototype PCBs

from I to 6 layers

P&PELECTRONICS

Design of Electronic Systemsby Degree Qualified Engineer

01924 402931

POWER SUPPLY DESIGNSwitched Mode PSU

Power Factor Correction

designed to your specification

Tel/Fax: 01243 842520

e-mail: eugen_kus@cix.co,uk

Lomond Electronic Services

WANTED

WANTED Surplus or Obsolete Electronic Components

Turn your excess stock into instant cash!SEND OR FAX YOUR LIST IN STRICTEST CONFIDENCE

Will collect anywhere in the UK

MushroomCOMPONENTS

6a St.Marys St, Bedford, Bedfordshire, MK42 OASTel: 01234 363611 Fax: 01234 326611

E-mail: sales@mushroomcomponents.comInternet: www.mushroomcomponents.com

For a FREE consultation onhow best to market yourproducts/services to aprofessional audience

contact REUBEN

on 020 8722 6028

rlr

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Obi

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Atlas LCR Passive Component Analyser (Model LCR40)

"No other LCR is as easy as this!"Just clip on the test leads and press test. The Atlas LCR willidentify the type of component, apply the appropriate testlevel and frequency, display the component's value andmore!Probes are detachable too, so you can use the optional SMTtweezers for your tiny unmarked passives - fantastic.

Inductance range: 141 to 10HCapacitance range: 1pF to 10,000µFResistance range: 10 to 2MQBasic accuracy: 1%Test signals: 1V, 3mA max

£79fill pm:c

Check and identify

semiconductor analyser your semi's .

fully inclusive

enclosure colours may vary

Automatic component identification(Inductor, Capacitor or Resistor).

Component value measurement.Automatic test frequency selection(DC, 1kHz, 15kHz or 200kHz).Inductor DC resistance measurement.

Non-volatile probe compensation memory.

Detachable probes allowing use of optionaltest prods, SMT tweezers, etc...Hands free mode with value hold.

Automatic component identificationPinout identification

Transistor gain measurement

MOSFET gate threshold measurementPN junction characteristics measurementShorted Junction identification

Transistor leakage measurement

Just connect the part anyway round and pressthe button!

Auto power on/off

Supports:

Bipolar transistors,Darlington transistors,

Diode protected transistors,Resistor shunted transistors,

Enhancement mode MOSFETs,Depletion mode MOSFETs,

Junction FETs,Low power triacs and thyristors,Diodes and diode networks,LEDs (+bicolours)

Lots ofaccessories

available soon!

NPH biPolarDarlineton

Diode Protectionbetween C-E

Resistor shuntbetween B-E

Current eainWe=126

Enhancement modeN-Ch MOSFET

.hold

BLUEmit.

Visit www.peakelec.co.uk to download the data sheets, user guides and copies of independent Also available from: (prices vary)

reviews. You can pay using a cheque, postal order, credit or debit card and even pay securelyonline. Please contact us for your volume requirements.

PE Kelectronic design ltd

Atlas House, Kiln LaneHarpur Ind. Est., Buxton

Derbyshire, SK17 9JL, UK sales@peakelec.co.ukTel. 01298 70012 Fax. 01298 70046

www.peakelec.co.uk

IA

CL3

THERE IS INTERESTING NEWS

P C T OL MEAURING INSTRUMENT

COMPLETE PACKAGE STARTING AT £ 331

OSCILLOSCOPE VOLTMETER

The Handyscope 3 is a powerful and versatile two channelinstrument with an integrated function generator.

° USB 2.0 connection (USB 1.1 compatible)° sample speed up to 100 MHz per channel° 8 to 16 bit resolution (6 /Volt resolution)° 50 MHz bandwidth° input sensitivity from 200 mVolt up to 80 Volt° large memory up to 131060 samples per channel° four integrated measuring devices° spectrum analyser with a dynamic range of 95 dB° fast transient recorder up to 10 kHz° several trigger features° auto start/stop triggering° auto disk function up to 1000 files° auto setup for amplitude axis and time base° auto trigger level and hysteresis setting° cursor measurements with 21 read-outs° very extensive function generator (AWG) 0-2 MHz , 0- 12 Volt

measuring

FILL -4J ._,1ilitINL'Ji -1Lefftgial-fl,

ETIEL,1_1011T2dL1111,7eNaS2IF

for more information, demo software, software, source code and DLL's visit our internet page: http://www.tiepie.now

TiePle engineering (NNKoperslagersstraat 378601 WL SNEEKThe NetherlandsTel: +31 515 415 416Fax: +31 515 418 819

TiePie engineering (UK)28, Stephenson Road, St. Ives

Cambridgeshire, PE17 3WJ, UKTel: 01480-460028

Fax: 01480-460340 7CA-

© Copyright 2002 TiePie engineering. All rights reserved.