ELECTRONICS AUSTRALIA'S `CIRCUIT AND DESIGN IDEAS' name + date Pumping up the Powerup - hints for the August 2000 project Sep 00 Car lamp failure warning - brake lights Sep 00 Globes flasher for the festive season (240VAC) Sep 00 Professional finish for aluminium panels Aug 00 Soundcard input protector - clipping preamp + indicator Aug 00 Better smarter blown-fuse indicator - see May 2000 CDI Aug 00 7-segment AC/DC indicator Jul 00 Driver for digital countdown timer - switch clock/watch Jul 00 Dual mode battery charger - 12V, const current & trickle Jul 00 Simple Waa-waa circuit Jul 00 Overvoltage protector for 3-terminal regulators Jun 00 The Dip Led - a LED DIP meter Jun 00 Golf buggy speed control Jun 00 Clipping indicator for opamp stages Jun 00 Versatile latching touch switch May 00 Low-cost, high-current regulator May 00 Smarter blown-fuse indicator May 00 Cooling fan controller saves power May 00 Exclusive-OR (XOR) function from discrete components Apr 00 12V battery conditioner (discharge checker) Apr 00 Speed up relay closing time Apr 00 Soft audio limiter Mar 00 Linux/PERL sprinkler script for Serial I/O Interface (Jul 91) Mar 00 Funway doorbell modification - auto shutdown Mar 00 Simple ESR tester (meter) Mar 00 Simple, beefy dual power supply Feb 00 Variable stero field circuit Feb 00 DC to DC converter for small valve radios Feb 00 Multipoint digital temperature monitor (LCD readout) Jan 00 Brother Multifunction Centre (MFC) to PC interface Jan 00 Cheap and cheerful tensistor tester Jan 00 Fitting modular telephone plugs Dec 99 LAN cable tester Dec 99 Parallel port interface (with BASIC software) Dec 99 Measuring very high value capacitors Dec 99 Drilling template for PCBs Nov 99 Soldering iron controller Nov 99 Simple 240VAC power switching for (ATX) PCs Nov 99 Servo amplifier Nov 99 LED mains voltage monitor Oct 99 Phone recording device switch Oct 99 Illuminated button, turn-off delay for Designer Door Alert Oct 99 Remote alarm to central-locking interface for cars Oct 99 Let your PC talk to IIC (I squared C) devices Sep 99 Water tank level monitor Sep 99 Use salvaged VCR sensors Sep 99 Two ICs drive two stepper motors Aug 99 PC's CMOS battery replacement Aug 99 Single channel IR remote control Aug 99 Simple LED voltmeter using 741 opamps Jul 99 Screecher MkII car alarm modification Jul 99 Solid state ballast bypass for cars Jul 99 Logic analyser uses TI graphing calculator Jul 99 Downlight controller Jul 99 Water detector - simple & efficient Jun 99 Car detector for driveways - imbedded coil Jun 99 Soft start for car lights Jun 99 ESR & charge current tester for car batteries Jun 99 Auto arming EA's engine immobiliser May 99 Low dropout voltage regulator May 99 High efficiency LED flasher May 99 Automatic central locking while driving May 99 Simple DC supply needs no thermal mounting hardware Apr 99 Door watcher - multiple doors Apr 99 Brakelight monitor for cars and trailers Apr 99 High-power alarm/siren driver (12V) Apr 99 'Pulser' for car electric fuel pumps Mar 99 Alarm status indicator - for home and car alarms Mar 99 Electronic 'Stomp Box' Mar 99 Mains usage monitor Mar 99 Two line, 10-channel control Feb 99 Clap-operated on/off switch Feb 99 Ring cadence simulator Feb 99 Current control for stepper motors Feb 99 Sound operated relay Jan 99 Flashing third brake light for cars Jan 99 Phase Bridge gives a free third audio channel Jan 99 Simple surround sound system - passive Dec 98 Bore pump timer Dec 98 Trailer light supply for European cars Dec 98 VHF preamplifier Dec 98 Wireless TV pattern generator - simple Nov 98 Loss of mains power indicator Nov 98 Curve tracer adaptor for DSOA Nov 98 Themocouple thermostat - mains swicthing Nov 98 Solar regulator (Nov/Dec 1994) modification Oct 98 Voltage controlled rotating LED display Oct 98 Whistler receiver for Earth's natural radio Oct 98 Uninterruptible Power Supply (UPS) for cordless phones Oct 98 Low current bargraph display Sep 98 Univeral IR controller for a PC - Infrared record/playback Sep 98 Novel running light display (chaser) Sep 98 Simple mod to improve Cable Break Finder (Feb 98) Sep 98 Linking up smoke alarms Aug 98 Simple inductance measurement using a CRO Aug 98 Photographic timer Aug 98 Longer battery life for the ESR meter Aug 98 AM radio re-transmitter Jul 98 Plant moisture monitor Jul 98 Infrared (IR) intruder alarm Jul 98 Automotive timing light - simple Jul 98 DIY keypad for microprocessors Jun 98 3V xenon strobe Jun 98 Driveway detector using pneumatics (garden hose) Jun 98 LCD digital panel meter input isolation circuit Jun 98 ESR meter measures batteries, too May 98 Low power bargraph voltmeter for cars May 98 40109 based Schmitt trigger - variable threshold May 98 Simple voltage reference for Pocket Sampler May 98 Hardware screen saver (PIR sensor) Apr 98 Fuel pump safety cutout for cars Apr 98 Mercury tilt switch alarm - (portable) Apr 98 Micropower single gate LED flasher Apr 98 Four by four-second voise recorder (ISD1416 chip) Mar 98 Car engine immobiliser with alarm Mar 98 Simple counting metronome with accented beat Mar 98 Add-on for Frequency Shifter project (gain/level management) Feb 98 Simple electronic key with time delay (12V) Feb 98 Radio control fail-safe with voltage guard Feb 98 Aid for soldering SMD components Jan 98 PC control for stepper motors Jan 98 Resonance meter and capacitor tester Jan 98 Electric fence tester Jan 98 Frequency divider gives 1:1 mark/space ratio output Dec 97 LED light supports wide supply range Dec 97 Pump controller for solar water heater Dec 97 Voltage reference modification for Pocket Sampler Dec 97 Electronic wind vane Nov 97 Finding breaks in shielded cables Nov 97 Turbo timer for diesel engines Nov 97 Zero blanking for 3.5 digit display (74C926) Nov 97 Telephone intercom Oct 97 Long duration one-shot Oct 97 Low dropout 5V regulator Oct 97 Simple sampler - uses PC parallel port Sep 97 Inexpensive power converter: 12VDC to 240VAC Sep 97 Headlights off indicator for cars Sep 97 JFET test adaptor for DMMs Sep 97 FM transmitter uses varicap tuning Aug 97 Booster for 12V motors Aug 97 Eye level car brake light flasher Aug 97 Unipolar stepper motor driver Aug 97 Automatic PIR doorbell Jul 97 Video test generator Jul 97 Front panels made easy Jul 97 Simple voltage regulator Jul 97 Supply makes LCD meter self-powered - 10V switching supply Jun 97 Micro-powered sound switch - uses latching relay Jun 97 Rugged 'knock' sensor Jun 97 Bit pattern detector aids micro development Jun 97 PC parallel port servo controller May 97 Light activated switch for battery powered circuits May 97 Simple temperature sensor gives linear output May 97 Language switch for Video CD players May 97 Chart for calculating file download times Apr 97 Suppy switching provides under-voltage lockout Apr 97 Delayed turn-off for car power windows Apr 97 Solid state switch for temperature controller - ref Aug 94 Apr 97 Heater switching system gives 3dB steps Mar 97 Turn indicator/blinker for cars Mar 97 Low voltage alarm for R/C receiver batteries Mar 97 Electro-mechanical battery charger Mar 97 Water level sensor Feb 97 Simple sleep timer for battery powered radio Feb 97 Remove components from PCBs with common heatgun Feb 97 UHF TV antenna Feb 97 Network cable tester Feb 97 Easy remote control tester Jan 97 Capacitance adaptor for analogue meters Jan 97 Car brake pedal alarm Jan 97 12V supply for compact fluorescent lamps Jan 97 Automatic video switching circuit Jan 97 Simple audible crystal checker Dec 96 Go/no-go tester for car ignition modules Dec 96 Brewer's temperature controller Dec 96 Frequency counter calibrator uses TV Dec 96 ADC supports up to 256 inputs Nov 96 Quiet line/buzzer alert for coms handset Nov 96 Battery charger auto cutout Nov 96 Crystal filter with variable selectivity Nov 96 Polarity probe - for cars Oct 96 Auxiliary telephone ringer Oct 96 Meter overload protector Oct 96 Clock alarm driven remote switch Oct 96 Port-powered MIDI interface fro the Mac Sep 96 CTCSS signal switching system Sep 96 Twin joystick adaptor for PC sound cards Sep 96 Overrange indicator for 1MHz pulse generator (June 92) Sep 96 One LED indicator for two computer hard drives Aug 96 Turn indicator warning device for cars Aug 96 Auto arming ignition killer for cars Aug 96 Clipping indicator for hifi amplifiers Aug 96 Simple temperature switch - germanium diode sensor Jul 96 1-bit fast ADC - stackable Jul 96 Off-air alarm for for radio studio Jul 96 One dollar watchdog timer for '8051 micros Jul 96 Rotary pot to 4-bit BCD converter Jun 96 Low cost emergency light system Jun 96 Simple timer for battery chargers Jun 96 Frequency meter for 'Vernus' audio sweeper (see Aug-Sept 92) Jun 96 Campervan fridge battery cutout - with warning beeper May 96 Computer network cable tester May 96 555 based waveform generator - square, triangle, sine May 96 Fax/modem computer auto power on May 96 Very low current LED flasher Apr 96 Sound intensity (level) meter Apr 96 Earth loop eliminator Apr 96 Sound triggered alarm Apr 96 Three-line intercom Mar 96 Simple battery charger - for NiCads, with 12 hr timer Mar 96 Handheld audio signal generator Mar 96 Low voltage monitor/indicator Feb 96 NiCad battery pack auto cut-off Feb 96 Clock auto dimmer - dims LEDs at night Feb 96 Plant moisture monitor Feb 96 Digital code lock - 4-bit Feb 96 12V battery charger - lead-acid, gates, etc Jan 96 Dual train controller - two trains on one track Jan 96 Simple logic probe Jan 96 Protected 50 ohm, 50dB pad (for comms) Jan 96 Reaction timer Dec 95 Microwave high-voltage diode tester Dec 95 Charging 12V NiCads from a 12V battery Dec 95 Personal emergency alarm (UHF link) Dec 95 24V to 12V DC converter for trailer lamps Nov 95 Multi-flash adaptor for cameras Nov 95 Phase controller for inductine loads - 240VAC Nov 95 Simple computer interface (+ BBS software) Nov 95 Simple inductance meter Oct 95 Simple capacitance meter Oct 95 Engraving pen Oct 95 Tap-on connections (attaching wires to car looms) Oct 95 Phone ring indicator (lamp) Sep 95 Solar panel booster - 3V to 9V Sep 95 Fan speed controller - 12V Sep 95 Variable timer Sep 95 Expanded scale voltage meter Sep 95 Micropower LED flasher Aug 95 NiCad battery charger - AC type Aug 95 Brake fluid level alarm Aug 95 Energy saver for computers Aug 95 Falling bomb simulator Jul 95 Water purity tester Jul 95 Silent telephone bell (lamp, via SS relay) Jul 95 Wideband current feedback amplifier Jul 95 Simple energy monitor (for mains power) Jun 95 Flashing beacon (programmable) Jun 95 Stable 100kHz source Jun 95 Oil temperature indicator for engines Jun 95 Etching PCBs (fast, no ferric chloride) May 95 First-event indicator (first of 16) May 95 Solar night light May 95 Switch-mode battery charger (lead-acid, gel) May 95 EA Light and Sound Trigger modification Apr 95 In-circuit transistor tester Apr 95 Fridge cooler (fan controller) Apr 95 Karaoke converter Apr 95 Current limiting switch (overload protection) Mar 95 Voltage and continuity tester for cars Mar 95 Cable tester (simple) Mar 95 NiCad cell tester Mar 95 Simple TRF radio Feb 95 Piezo screamer Feb 95 DTMF decoder Feb 95 LED display driver Feb 95 Dual polarity power supply Feb 95 Efficient linear power supply (1.25V - 30V @ 3A) Jan 95 Energy auditor (record appliance on-time) Jan 95 DVM milliohm adaptor Jan 95 Simple shed door alarm Jan 95 Temperature controller Dec 94 Transformer protector Dec 94 Speed controller for DC motors Dec 94 CDI for an outboard motor Dec 94 Telephone ring simulator Dec 94 DC voltage status indicator Nov 94 Crystal controlled timer Nov 94 Simple variable-temperature soldering iron Nov 94 Signal injector/tracer Nov 94 High voltage generator Nov 94 Simple solar powered light (charges NiCads) Oct 94 Computer controller for DC motors Oct 94 Simple two-tone doorbell Oct 94 Bicycle tail light Oct 94 Trailer reversing light Oct 94 Sound indicator for the sight-impaired Sep 94 Electronic fuse Sep 94 DTMF keypad interface Sep 94 Binary clock Sep 94 AC (mains) voltage finder Aug 94 Gel cell battery charger Aug 94 Guitar tuner Aug 94 Sensor-light operated door bell Jul 94 Closed loop alarm Jul 94 Keyless lock Jul 94 RPM (rev) meter Jul 94 Simple solar cell voltage regulator Jun 94 NiCad charger with peak voltage detection Jun 94 Simple capacitance meter Jun 94 Disk drive stepper motor driver Jun 94 Active guitar electronics (preamp) May 94 Compact logic probe (simple) May 94 Touch switch for dirty fingers May 94 Garage door circuit (simple) May 94 Sound interface for PCs Apr 94 Tri-mode LED light chaser Apr 94 Simple `twin tone' doorbell Apr 94 Amiga conversion for EPROM programmer Apr 94 Large capacitor tester Mar 94 80m shielded loop Mar 94 Intelligent battery charger (NiCad, delta peak det.) Mar 94 Model traffic lights Feb 94 Audio attenuator design Feb 94 Flashing lamp driver Feb 94 Mower battery voltage control Jan 94 Keyhole light Jan 94 Electrically-operated garage door Jan 94 Op-amp toggle Dec 93 Efficient +5V regulator Dec 93 Temperature compensated charger - SLA batts. Dec 93 Switching 240V relays Dec 93 Bi-directional PC port Nov 93 IR proximity detector Nov 93 Telephone STD bar Oct 93 Guitar distortion Oct 93 Add-on vibrato for toy organ Oct 93 Variable supply for masthead amp Sep 93 Lights after dark Sep 93 `Over-drive' circuit Sep 93 Electric fence tester Sep 93 Seven day indicator Aug 93 Shorted turns tester Aug 93 Circuit resistor substitute Aug 93 NiCad discharger Aug 93 Eight bit PWM Jul 93 DWM battery saver Jul 93 Transmission indicator Jul 93 Blinker reminder Jul 93 Logic gate identifier Jun 93 Cat detractor Jun 93 Courtesy light delay Jun 93 Pulser probe Jun 93 Old VCR remote controls May 93 Fuzz and wah-wah pedal May 93 Remote control tester May 93 Direct conversion receiver May 93 Audible logic probe Apr 93 Short/open detector Apr 93 Joystick fire button Apr 93 Battery checker Mar 93 Level indicator Mar 93 IR remote control Mar 93 Car light extender and headlight reminder Mar 93 Metronome with emphasised beat Feb 93 Audio test oscillator Feb 93 Transistor leads finder Feb 93 I/O for the Amiga Feb 93 Receiver modules Jan 93 Automatic turn off switch Jan 93 High current pulses Jan 93 Current-limited 120V regulator Dec 92 Twinkling star Dec 92 Fluorescent lamp driver Dec 92 Headlight warning Dec 92 Apple II robot controller Nov 92 Computer controlled power supply Nov 92 Improved adjustable three pin regulator Oct 92 Heightened stereo effect Oct 92 Telemetry converter Oct 92 TV headphones amp Oct 92 Foolproof battery charger (12V/20A) Sep 92 Electronic lock Sep 92 Multi-flash unit Sep 92 Master/slave power switch Aug 92 Fluorescent lamp driver Aug 92 Tastic timer Aug 92 Automatic scanning for CBs Jul 92 Car voltage monitor Jul 92 Acupuncture point finder Jul 92 On/off lighting switcher Jun 92 Modified Funway doorbell Jun 92 Audible temperature and oil alarm Jun 92 Constant-current transistor tester May 92 DC motor speed controller May 92 Mains-powered light delay May 92 Joystick fire button Apr 92 Short/open detector Apr 92 Remote control extender Apr 92 Audible logic probe Apr 92 Transistor leads identifier Mar 92 Capacitor leakage tester Mar 92 Sprinkler timer Mar 92 LED display board Feb 92 10 channel RS-232 device selector Feb 92 Automatic watering system Jan 92 Tristate buffer or OR gate Jan 92 1-99V DVM Jan 92 Car vandalism detector Dec 91 Temperature controller Dec 91 Turbo timer Dec 91 Sweep oscillator Dec 91 Poor man's logic probe Nov 91 Quiz game Nov 91 Computer interface Nov 91 Sound effects generator Oct 91 Low dropout voltage regulator Oct 91 Constant current charger Oct 91 Lightning meter for SWLs Oct 91 Automatic light switching Oct 91 12V battery regulator Sep 91 Crystal oven Sep 91 High-res LF adaptor for counter Sep 91 AM/FM car radio antenna Sep 91 RS-232 parallel converter Aug 91 Transistor pierce oscillator Aug 91 30V, 3A power supply Aug 91 Binary/gray/binary converter Jul 91 `No battery' alternator start-up Jul 91 Switching lamp dimmer Jul 91 40V inverter/doubler Jul 91 Remote IR tester Jul 91 LED torch Jun 91 Headphone amplifier Jun 91 Inbuilt VCR alarm Jun 91 Darkroom exposure meter Jun 91 Timer with memory May 91 Optical shaft encoder May 91 Water reticulation control box May 91 `Turbo' board for Tandy 1000 Apr 91 TV-locked frequency calibrator Apr 91 Mods to Aug 1990 logic probe Mar 91 LED signal indicator Mar 91 Online flasher Mar 91 Mains' frequency indicator Feb 91 Active antenna balun/preamp Feb 91 Windscreen washer tank monitor Feb 90 NiCad battery protector Jan 91 Courtesy light fader Jan 91 Crystal set AM tuner Jan 81 IR proximity detector Jan 91 Valve TV transformer provides isolation Dec 90 Xenon timing light Dec 90 Microwatt LED flasher Dec 90 Simple RF preamp Dec 90 `Easy fit' wiper delay Nov 90 Scrabble timer Nov 90 Improved ignition killer Nov 90 Audio reminder for bike blinkers Nov 90 Two-tone oscillator for SSB testing Nov 90 Logic probe Oct 90 Resettable games timer Oct 90 Battery operated strobe `beacon' Oct 90 Servo system for robotics Oct 90 Poor man's variac Sep 90 `Mosmarx' voltage multiplier Sep 90 Four component window detector Sep 90 Photographic slave flash Sep 90 Serial keypad encoder Aug 90 Tuned mains filter Aug 90 Seedling heater thermostat Aug 90 Novel `decision maker' Aug 90 Water level alarm Aug 90 Car alarm protector Aug 90 LED `scanner' VU display Jul 90 24 channels for ICOM 22S Jul 90 Quiz game circuit Jul 90 Improving a low cost phone Jul 90 Linear UJT sawtooth oscillator Jun 90 Checkerboard pattern generator for ATV Jun 90 QRP transmitter for 6m Jun 90 Op-amp `flipflop' Jun 90 Low battery voltage alarm May 90 Video dubbing sound editor May 90 Flexible variable supply May 90 Eight bit decode display driver Apr 90 Auto polarity selector Apr 90 `Auto' volume control Apr 90 Hi-efficiency 1.5V LED flasher Apr 90 Seed bed mist timer Mar 90 High current switchmode PSU Mar 90 High power dummy load Mar 90 Level control for well water Mar 90 IR proximity detector Feb 90 Automatic switch for Centronics printers Feb 90 Current sensing pilot lamp Feb 90 Milliohm DMM adaptor Jan 90 12V/240V inverter for 80W fluoro lamp Jan 90 TTL logic probe Jan 90 RS-232 data monitor Jan 90 Mains controller for Commodore 64 Dec 89 Bi-directional motor controller Dec 89 Low power inverter Dec 89 Stereo dynamic expander Dec 89 Reading remote keypads in hostile environment Nov 89 Audio digitiser for Amiga Nov 89 Alarm for deaf people Nov 89 Doorbell pushbutton turns on porch light Nov 89 12-bit A to D converter Oct 89 Manual control for automatic car antenna Oct 89 Remotely adjustable aerial attenuator Oct 89 Neater wire joints Sep 89 Joystick for IBM compatibles Sep 89 Test message generator Sep 89 Midi tester, opto replacement Aug 89 Synthetic dual matched pot Aug 89 Powering solid state gear from valve equipment Aug 89 Mains failure alarm Aug 89 Oscilloscope aid for microprocessors Aug 89 High-Z voltmeter Jul 89 `Lights on' alarm Jul 89 Digital dice Jul 89 Joystick `Y' adaptor Jul 89 Telephone ring/busy dialtone detector Jul 89 Keyboard sound improver Jun 89 Substitute for multi-turn pot Jun 89 Self-arming ignition killer Jun 89 Parts counter Jun 89 Claytons car alarm May 89 Decimal display of binary numbers May 89 Slave flash unit May 89 Combination lock May 89 Joystick auto fire Apr 89 Guitar tuner Apr 89 Tape fader Apr 89 High impedance amplifier Apr 89 $20 plasma display Mar 89 One chip audio mixer Mar 89 Transformer tips Mar 89 Switch interlock Mar 89 Propeller tacho Feb 89 Recharger for single dry cells Feb 89 Multiple dry cell recharger Feb 89 Fan controller Feb 89 Electrolytic capacitor tester Jan 89 Logic testers Jan 89 Serial to parallel interface Jan 89 TV antenna switching Dec 88 Cascading regulators Dec 88 RS232 wiring tester Dec 88 One button on-off Dec 88 Leading zero blanking Dec 88 Beat trigger strobe light Nov 88 Logic level change detector Nov 88 Cascading 4017 counters Nov 88 Capacitance meter Nov 88 Operating a relay at reduced voltage Oct 88 250VA inverter Oct 88 Solid state `soft start' relay Oct 88 Suppressed zero voltmeter Sep 88 Three transistor amplifier Sep 88 Backup alarm control Sep 88 High pass filter for TV Aug 88 Sump/bilge pump controller Aug 88 Dimmer for torches Aug 88 TTL-RGB to composite video converter Aug 88 Standby power supply monitor Jul 88 14H battery charging timer Jul 88 Logic pulser Jul 88 Electronic BCD switch Jun 88 Four digit combination lock Jun 88 Car battery discharge indicator Jun 88 `Keep awake' for Concertmate 500 May 88 Linear scale on/off timer May 88 Soldering iron timer with `time up' beeper Apr 88 Electronic `flasher' novelty Apr 88 12V stroboscope for portable use Apr 88 Geiger counter Mar 88 Darlington assisted switch Mar 88 Auto-run circuit for fridges Mar 88 Cutting holes in Scotchcal Dynamark labels Mar 88 D/A and A/D for Apple II Feb 88 Light chaser/controller Feb 88 Automatic switching for UHF converter Jan 88 Expanding range of capacitance meter Jan 88 Improved glow plug regulator Jan 88 Multi-channel display Dec 87 Electronic die for games Dec 87 Soldering iron timer Dec 87 Fast peak limiter Dec 87 I/O expansion for Apple II+ Nov 87 Deep-cycle NiCad charger Nov 87 Refrigerator auto-run unit Nov 87 Improved battery charger controller Oct 87 Car accessories timer Oct 87 Cable tester Oct 87 Turn indicator flasher Sep 87 Centronics interface for Apple II Sep 87 Wipe effects for the video fader Sep 87 24V/12V regulator Aug 87 Simple doorbell Aug 87 El cheapo frequency reference Aug 87 Low battery indicator Aug 87 Complex impedance meter Aug 87 Low current circuit breaker Jul 87 General purpose counter Jul 87 Benchtop DC ammeter Jul 87 Memory expansion for the VIC-20 Jul 87 Dual rails from a single battery Jun 87 Transistor tester add-on for multimeter Jun 87 Magnetic pickup for digital speedometer Jun 87 Screecher protection for bonnet and boot Jun 87 Quiz game adjudicator Jun 87 16K memory for VZ-300 computer May 87 Tone decoder for CBers & amateurs May 87 TV hearing aid May 87 Crude but simple voltage reducer May 87 Battery backup for bicycles Apr 87 Brightness control for torches Apr 87 NiCad charger with auto float charge Apr 87 Precision V/F converter Apr 87 IC preamplifier Mar 87 Low current power amplifier Mar 87 Temperature comparator Mar 87 Great circle calculator for the Amstrad 6128 Mar 87 Sensitive trigger for slave flash guns Feb 87 Four utility circuits using a hex Schmitt trigger Feb 87 ECG waveform display on Apple II computer Jan 87 Digital speedometer for cars Jan 87 Computer drive for EA EPROM programmer Jan 87 Loudspeaker switching circuit for car/radio/cassette Dec 86 Rechargeable 12V torch Dec 86 Brake lamp flasher modification Dec 86 Radio remote control Dec 86 Decimal points for EA 500MHz DFM Dec 86 Basic program for vented box enclosures Nov 86 Modified audio generator Nov 86 Extra decimal points for EA DFM Nov 86 TV based frequency standard Nov 86 Addenda for 1.5V photoflash inverter Oct 86 Ignition switch cutout for car alarms Oct 86 Low pass filter and surge suppressor Oct 86 How to cascade 4017 counters Oct 86 Improved model railway lighting Oct 86 How to gang single potentiometers Sep 86 Battery charger controller Sep 86 Amplitude modulation for function generator Sep 86 Whistle stopper for PC birdies Sep 86 Electronic sprinkler timer Aug 86 Connecting VCR to two TV sets Aug 86 1.5V photoflash inverter Aug 86 Electronic vibrator for car radio Jul 86 Wien bridge sinewave oscillator Jul 86 Farm gate movement detector Jul 86 Strength meter for parties Jul 86 Negative rail from bridge power supplies Jun 86 Low cost technique for diagnostic training Jun 86 Setting the output of the 300W inverter Jun 86 A mouse for the cat Jun 86 Lights on reminder for cars Jun 86 Sound effects for toy guns Jun 86 Microprocessor memory expansion Jun 86 High performance audio generator May 86 FM and AM modulation for EA function generator May 86 Burglar alarm deterrent flasher May 86 Computer program aim beam antennas May 86 Microphone preamp and peak level indicator Apr 86 Cure for doorbell pests Apr 86 Automatic shut-off for soldering irons Apr 86 LED tuning indicator for AM stereo decoder Apr 86 Novel lamp flasher uses no capacitor Mar 86 Code switch Mar 86 LED flasher for torches Mar 86 Desoldering tools for ICs Feb 86 Three way combination lock Feb 86 Modified soft pedal for Lyrebird piano Feb 86 People monitor and light switch Jan 86 Ignition advance for alternative fuels Jan 86 A clutch of charge pumps Dec 85 Knight Rider scanner light Dec 85 Solid state bicycle tail light Dec 85 Speed control monitors Dec 85 16 channel data samples for Microbee Nov 85 Infrared door minder Nov 85 Camera timer Nov 85 Digital logic tester Nov 85 Audible engine temperature alarm Nov 85 Video controlled power switch for TV Nov 85 Balanced microphone input stage Oct 85 Modification to Pools/Lotto selector Oct 85 Projection lamp warm up unit Oct 85 Night time lamp flasher Oct 85 Solar panel regulator Oct 85 Headlight reminder and burglar deterrent Sep 85 Auto dialling/auto answer attachment for modems Sep 85 3-1/2 digit display controller Aug 85 Operating relays from low voltage supply Aug 85 Adjustable supply to +/-100V at 0.25A Aug 85 Latched indicators for multi-sector alarm Jul 85 Combination switch/lock Jul 85 Radio/cassette addition to motorcycle intercom Jul 85 4000 series CMOS gate tester Jul 85 CRO adaptor for RMS measurements Jun 85 Infrared diode amplifier Jun 85 Hee haw siren using piezo buzzer Jun 85 88kHz notch filter for CD players Jun 85 Infrared remote keyboard Jun 85 Low cost transistor tester May 85 Calibrating meter shunts May 85 Inverter modification May 85 Ding dong doorbell May 85 Cistern pump timer Apr 85 Program for RS232 printer interface Apr 85 Headlight control circuit Apr 85 Sequential controller for tape recorders Apr 85 Knight Rider scanner light Mar 85 300 baud infrared data link Mar 85 Low power relay energisation Mar 85 Inverse RIAA attenuator Feb 85 Guitar tuner Feb 85 Breakdown voltage test jig Feb 85 Ultrasonic alarm Feb 85 Modification to Railmaster train controller Jan 85 Beeper for vehicle flasher Jan 85 Checking transistors with a multimeter Jan 85 Capacitance meter Jan 85 Pulse generator Jan 85 Low noise mic pre-amp Dec 84 Modifying the EA car alarm Dec 84 Automatic turn-off switch Dec 84 Impulse tacho for TAI Dec 84 Monophonic organ Dec 84 24V to 12V converter Dec 84 Multi-channel CRO adaptor Nov 84 RS232C serial A-D converter Nov 84 Metronome with accented beat Nov 84 13.8 power supply Oct 84 Quiz game adjudicator with digital scoring Oct 84 50Hz frequency indicator Oct 84 Baud rate generator Oct 84 Childproofing battery operated doorbells Oct 84 Video switch for Apple computers Oct 84 Light sensitive switch Oct 84 IF/audio circuit for VHF receiver Oct 84 Auto-chime modifications Sep 84 Adjustable peak limiter Sep 84 CMOS touch switch for infrared TV sound control Sep 84 Thermal balance switch Sep 84 Glitch catcher and line filter Sep 84 Car alarm Sep 84 Automatic antenna retraction Sep 84 Two way radio alarm tone generator Aug 84 Improved graphics for VZ200 computer Aug 84 Logic pulser probe Aug 84 Dual counter trip meter Aug 84 6V car adaptor Jul 84 Fuse-failure indicator Jul 84 Wireless link for musical keyboard Jul 84 Bi-colour LED gives varying hue Jul 84 Burglar alarm reminder Jul 84 Crowbar protection for 13.8V supplies Jun 84 Automatic volume control Jun 84 Modified supply for storage CRO adaptor Jun 84 Single pushbutton long period timer Jun 84 Extended response sound switch Jun 84 Audible indicators for panel lamps Jun 84 Car navigation aid May 84 Fluid level detector May 84 Tone generator for Super-80 computer May 84 Digital sweep/market generator Apr 84 Modifying the EA EPROM programmer Apr 84 High power dummy loads Apr 84 Variable frequency oscillator Mar 84 Throbotron light show Mar 84 EPROM programmer beeper Mar 84 Burglar alarm Mar 84 10A regulated photo enlarger supply Mar 84 VIC-20 video terminal Feb 84 NiCad charger with automatic shutoff Feb 84 SWR meter Feb 84 Linear frequency control for the 555 timer Feb 84 Extra RAM for the VIC-20 Jan 84 Multiple flash trigger for camera flash guns Jan 84 Hex display for EPROM programmer Jan 84 Stereo sound for TV Dec 83 NiCad charger Dec 83 Improving the solenoid Nov 83 Effective joystick Nov 83 Dual trace CRO adaptors Nov 83 Flame detector circuit controls booster fans Oct 83 Wide range capacitance meter Oct 83 IC sockets and double sided boards Oct 83 Glow plug driver for model planes Oct 83 Frequency doubler uses one comparator Oct 83 Mains derived TTL clock Sep 83 Beeper for the Super-80 Sep 83 Regulated enlarger power supply Sep 83 Transient muting for preamplifier Sep 83 Battery indicator for small boats Sep 83 Mounting small speakers Sep 83 Electronic detent circuit Sep 83 Tachometers and CD ignition systems Aug 83 EPROM adaptor for EA programmer Aug 83 Modified light chaser gives cylon eye display Aug 83 PCB pattern suggestion Aug 83 Wide range low distortion sweep oscillator Aug 83 Reverse polarity protection circuit Jul 83 Heavy duty joystick for VIC-290 Jul 83 Composite video signal generator using NOR gates Jul 83 Digital clock monitor with audible output Jul 83 Extra RAM for the DREAM 6802 microcomputer Jul 83 Leading zero blanking for Playmaster AM Jun 83 Quiz game adjudicator Jun 83 Updating the pools/lotto selector Jun 83 Audio indicator for the heart rate monitor Jun 83 Economy meter with km/l readout May 83 Hold function for digital frequency meter May 83 Pushbutton sequential switch May 83 Cassette interface for the VIC-20 PC May 83 Power failure indicator Apr 83 Model railway signal override system Apr 83 Analog multiplexer and op-amp D/A converter Mar 83 Current limiting for the VK Powermate Mar 83 Loudspeaker protection for high power amps Mar 83 Burnout protector for ohmmeter ranges Mar 83 500MHz prescaler for digital frequency meters Mar 83 Stripper modification for wire wrapping Feb 83 Suppressed zero car voltmeter Feb 83 Hex display for EPROM programmer Jan 83 Pre-regulator for EA power supply Jan 83 Improved triangle-to-sine wave converter Jan 83 Headlight reminder Dec 82 Expanded scale voltmeter Dec 82 Darkroom timer has audible output Dec 82 Personal portable modification Dec 82 Four tone sound for the Super-80 Dec 82 Digital chess clock with time out alarm Dec 82 Cudlipp's sister a ladybug Nov 82 Signal controller for model trains Nov 82 Relay power saver Sep 82 CRO trigger for EA TV pattern generator Sep 82 Remember the lights! Sep 82 Fractional frequency multiplier Sep 82 Bugging a lizard on the FM broadcast band Sep 82 Use your DVM as a capacitance meter Aug 82 Four hour photographic timer Aug 82 Computer as pattern generator Aug 82 Playmaster tone control bypass Aug 82 Regulated supply for flash meter Aug 82 Customised keytops Jul 82 TRS-80 cassette control Jul 82 Recycling etchant solution Jul 82 Fast switching solid state relay Jul 82 Resuscitation training aid Jul 82 Measuring top speed Jul 82 Transistor checker Jul 82 Programmed switch-on for IR remote control Jul 82 Lights for model railways Jun 82 Pseudo PC board Jun 82 Cudlipp's brother Jun 82 Audible logic tester Jun 82 Electronic thermostat Jun 82 Power inverter for motor driven antenna May 82 Alarm and fast shift for EA control timer May 82 Novel Wien bridge Apr 82 Auto repeat function for RCA VP 601 keyboard Apr 82 Mains auto transformer Apr 82 Register display routine for the `Sorcerer' Apr 82 Up/down pushbutton-controlled power supply Apr 82 Relay latching circuit Mar 82 Battery tester for the visually impaired Mar 82 Switch-mode control of low voltage DC motors Mar 82 Cure fluctuating dwell and tacho readings Mar 82 Suppressing audio switching transients Mar 82 Noise gate Feb 82 Low power probe Feb 82 Automatic reversing lamps Feb 82 Crowbar protector Feb 82 Use infrared relay as door minder Feb 82 Hum measurements Jan 82 LED indicator for remote AC loads Jan 82 Modifications to the utility timer Jan 82 `Patch' for Dream 6800 kaleidoscope program Jan 82 Audio flasher Jan 82 Musical tone generator peripheral Jan 82 Voltage to frequency converter Dec 81 Use your empty desoldering wick spool Dec 81 Balanced isolation amplifier Dec 81 Increased sensitivity for infrared relay Dec 81 Dynamic noise reducer for audio systems Dec 81 Random pulse width generator uses two ICs Dec 81 True peak-reading DC voltmeter Nov 81 Single button sequential switcher Nov 81 Calibrator for DC meters Nov 81 Video summing amplifier Nov 81 Single IC logic tester Nov 81 Variable-phase all-pass filter Oct 81 Pseudo random number generator Oct 81 Marine auto pilot for small boats Oct 81 Simulate a NiCad cell Sep 81 Regulator with low dropout voltage Sep 81 Headlight reminder alarm Sep 81 Touch Switch Sep 81 Active DC load Sep 81 NiCad battery charger Sep 81 Lifetime lettering Aug 81 Linear LED control Aug 81 Model train points changer Aug 81 IC testing board Jul 81 One transformer, two secondaries, three supply rails Jul 81 Random number generator with 3 ICs Jul 81 Bi-colour LEDs indicate switch position Jun 81 Decimal points for the 200MHz frequency counter Jun 81 Modified `Prospector' metal locator Jun 81 Tunnel diode wobbulator Jun 81 Intermediate intervals for utility timer Jun 81 More power from dual or quad op-amps May 81 Head/parking light reminder alarm May 81 Converting electronic music box to pushbutton operation May 81 Analog memory May 81 Electronic thermometer with digital display May 81 Simulation of ignition primary circuit pulses Apr 81 Up/down glide tone generator Apr 81 5V logic tester with audio buzzer Mar 81 Fuse failure indicator Mar 81 TTL over-voltage protection Mar 81 Add milliohms measurement to your digital multimeter Feb 81 Auto-start for 12-230V AC inverter Feb 81 Modification adds versatility to electronic keyer Jan 81 Lightning protection for high pass filter Jan 81 Voltage controlled amplifier Jan 81 Phase meter for audio frequencies Jan 81 Novel application for Mini Scamp Jan 81 VDU mod gives 64 characters per line Dec 80 High frequency doubling with CMOS Dec 80 Modification gives pulsed output for Utility Timer Dec 80 PLL lock indicator detects latching simply Nov 80 Wave shaper uses one 4017 IC Nov 80 15V/0.5A power supply with good regulation and temp stability Nov 80 Low voltage light chaser provides four separate outputs Nov 80 Economical white noise source Oct 80 LC network adapts PLL for crystal-overtone operation Oct 80 Symmetrical power supply Oct 80 Audio-visual continuity tester Oct 80 Timer takes very low current Oct 80 Automatic switch-off circuit saves batteries Sep 80 Bi-directional LED chaser Sep 80 Single switch doubles bridge voltage Aug 80 Digital readout for HF receiver using standard counter Aug 80 Unity gain buffer with wide frequency range Aug 80 Automatic multiple flash unit for photographers Aug 80 LED flasher Jul 80 Modification to wiper delay unit Jul 80 Improved resistance-capacitance oscillator Jun 80 Bridge measures unknown resistance and capacitance Jun 80 Headlight minder saves battery discharge May 80 555 timer triggered by positive pulses May 80 High pass filter for masthead amplifier May 80 Electronic security lock has non-volatile latch memory May 80 Mosto calculators for incremental counting Apr 80 Fuzz for electric guitar Apr 80 Self resetting burglar alarm Apr 80 Readout dimmer for six digital crystal clock Apr 80 Joystick control Mar 80 Decimal and binary learning tool Mar 80 Modification to sound triggered photo flash Mar 80 Test reaction times on the 2650 Mar 80 Solid state scope uses LEDs Mar 80 High current regulated power supply Feb 80 Direct derivation of baud rate clock signals from a 4MHz clock Feb 80 Novel way to play your old 78s Feb 80 Auto-chime - which tune is next? Feb 80 Make before break meter switching Jan 80 Counter records number of camera shutter openings Jan 80 On screen clock with 2650 Jan 80 Alarm for digital clock uses two CMOS oscillators Jan 80 Flash strobe addition to sound triggered photo flash Jan 80 Novel vice to make Dec 79 Adjustment power supply up to +/-12V and 800mA Dec 79 Frequency doubler Dec 79 Accurate motor speed control Dec 79 Autodim for fluorescent clock displays Nov 79 Six digit facility for four digit clocks Nov 79 TTL compatible audio switch Oct 79 Audio/video monitor for EA terminal keyboard Oct 79 Note on opto-coupled magnet driver for teleprinters Oct 79 Tracking dual voltage regulator Oct 79 Lock switch for desk mains digital clock Sep 79 Music for your lawn! Sep 79 Novel method for desoldering IC devices Sep 79 Voltage reference uses op-amp Sep 79 JFET preamplifier for tired receivers Aug 79 W1JR HF broadband balun Aug 79 Recording DC power using a chart recorder Jun 79 Opto-coupled magnet driver for teleprinters Jun 79 General purpose fault finding probe Jun 79 Comprehensive cable tester Jun 79 Interesting two-wire intercom May 79 Bounce free switch May 79 Variable current limiter for power supplies May 79 Transistor lead identification May 79 Protection for DC coupled speakers May 79 Noise generator Apr 79 Hee haw siren for toys Apr 79 Auto repeat for keyboard Apr 79 Handy aid to fine soldering Apr 79 Caravan DC power - a better way Apr 79 Dual function neon indicator Mar 79 Cross coupled transistor rectifier bridge Mar 79 Preamplifier for microphones, mixers, etc Mar 79 Wien bridge and op-amp select filter's bandwidth Mar 79 Try this simple diode tester Feb 79 Non-destructive backspace, space and line feed for VDU Feb 79 Crystal oscillator suits 2650 minicomputer Feb 79 CW operation on 3.5MHz transverter Feb 79 Modification lets PIPBUG work at 300 baud Feb 79 FM square and triangular wave generator Jan 79 Handy patch panel in a box Jan 79 D flipflops sense locked state of PLL Jan 79