There are 2702 circuit schematics available. Last circuit added on Saturday, 30 May 2015.

CircuitCategoryDate AddedOK?
Battlefield Laser Warning Receiver - Front-End AmplifierLaserMay 30, 2015
Battlefield Laser Warning Receiver - Log Amplifier / Comparator / AlarmLaserMay 30, 2015
13.8V 30-40A Power Supply (PDF)Power 
Yaesu FT-897 - PC interface (PDF)PC 
AT89C2051 serial COMs to LED driverMicrocontrollerApr 12, 2001
RCM710 electronic scale, technical manual including schematicTestApr 12, 2001
RS-232 line monitor and loopback cablesPCJan 26, 2001
Serial to parallel converter using the AT89C2051MicrocontrollerJan 26, 2001
Slave flash trigger with counting logic (Silicon Chip Mazine article)PhotoAug 18, 2009
Design of active filters with operational amplifiers (includes circuit and Java filter calculator)FilterJan 16, 2010
Filters for the RadioJove ReceiverFilter 
Autopilot: Do it yourself UAVModelsSep 10, 2006
Bridge headControlAug 14, 2002
Bat detector microphone pre-amplifiersPreamp 
Visor cradle serial interfaceGamesAug 09, 2002
TomTom One V3 connector pinoutPDAMar 27, 2009
Simple CW Keyer based on Atmel ATtiny 2313Microcontroller 
PWM motor controllerControlJun 06, 2003
Single and Two Cell White LED Drivers Without InductorsLEDSep 13, 2006
Laser link communicator project from Electronics Australia magazineLaser 
12V battery level indicator for car batteriesAutomotive 
Bicycle rear flashing LED lightLED 
Car burglar alarm circuitAutomotive 
Decision maker circuit diagramGames 
Egg timer circuit diagram, PCB layout and assembly informationTiming 
Electronic candleLighting 
Flashing light / emergency beacon for vehicleAutomotive 
3-up decision maker circuit diagramGames 
Headlight guardAutomotive 
Infrared beam door alarmIR 
LED dice with fast rollGames 
Interior light extenderAutomotive 
Little bike light using LEDsLED 
Simple metronome using LM1458Music 
LED dice using PIC16F88Games 
Simple moisture indicatorMisc 
LM380 2.5 watt audio amplifier circuitAmplifiers 
One transistor FM transmitter / FM bugging deviceTransmitters 
Two player quiz master gameGames 
4 channel 433MHz remote control transmitter / receiver based on SM5162 and SM5172 chipsRF 
Seatbelt reminder circuitAutomotive 
Solar trackerSolar 
Stereo audio amplifier based on TDA2822MAmplifiers 
Two LED trouble light systemAutomotive 
Two-tone doorbell using 555 timerMisc 
Two transistor FM transmitter / FM bugTransmitters 
Snore alarm electronic deviceMedicalAug 14, 2002
AT89C2051/4051scanning 7-segment display and keypadMicrocontrollerJan 26, 2001
AT89C2051/4051 Driving dot LEDMicrocontrollerJan 26, 2001
AT89C2051/4051stepper motor interfaceMicrocontrollerJan 26, 2001
AT89C2051/4051connecting dumb terminalMicrocontrollerJan 26, 2001
Motorola 68K SBC (single board computer)MicrocontrollerJun 20, 2004
8051 SBC (single board computer)MicrocontrollerJun 20, 2004
8051SBC V1.1MicrocontrollerMar 25, 2009
Atmel 89 Series Device ProgrammerMicrocontrollerMar 25, 2009
89S52 Project BoardMicrocontrollerMar 25, 2009
Digital Clock with Alarm Using DS1307TimingMar 25, 2009
Using the AT89C4051 as a RTC (real-time clock)MicrocontrollerMar 25, 2009
Home Automation Over InternetControlMar 25, 2009
Simple RS232C Level Converter using TransistorsMicrocontrollerJan 26, 2001
AVR ThermometerMicrocontrollerMar 25, 2009
Motorola 68HC11 evaluation boardMicrocontrollerJun 20, 2004
C-52 EVB Robot ControllerMicrocontrollerJan 26, 2001
Mains clock controller using AT89C2051MicrocontrollerJan 26, 2001
Data Acquisition & Logging System Using AT89c51 and Visual BasicData AcquisitionMar 25, 2009
DC Voltage and Current SourcePowerMar 25, 2009
Power supply provides +5VDC regulated, +10VDC unregulated and 7.5VACPowerJan 26, 2001
Controller for hybrid (photovoltaic- wind turbine and diesel engine) power plantPowerMar 25, 2009
AT89C2051/4051 Easy-DownloaderMicrocontrollerJan 26, 2001
AT89C51/52/55 Easy-DownloaderMicrocontrollerJan 26, 2001
PIC16F84 programmerMicrocontrollerJan 26, 2001
PIC16F84 miniature real-time controllerMicrocontrollerJan 26, 2001
Isolated RS232 for PIC16F84MicrocontrollerJan 26, 2001
PIC16F84 debugging terminalMicrocontrollerJan 26, 2001
Big 7-segment LED display board with SPI interfaceLEDJun 20, 2004
MiniLOGGER V1.0MicrocontrollerJan 26, 2001
Analog datalogger based on T89C51RD2MicrocontrollerJun 20, 2004
RS232C Level ConverterPCJan 26, 2001
MTK-85 8085 Microprocessor Training KitMicrocontrollerMar 25, 2009
The 89C51 PABXTelephoneMar 25, 2009
PC electrically isolated RS422 interface using SN75176B or MAX485PCJun 20, 2004
PC electrically isolated RS485 interface using MAX487 or SN75176BPCJun 20, 2004
Short circuit protected power supply from PC 12V supplyPCJun 20, 2004
Atmel 89C Series Flash Microcontroller ProgrammerMicrocontrollerJan 26, 2001
In-Circuit PIC Loader (ISP programmer) over parallel portMicrocontrollerMar 25, 2009
PIC18F2550 Project BoardMicrocontrollerMar 25, 2009
3rd harmonic distortion meter for measuring the quality of AC supplyPowerMar 25, 2009
Data Acquisition System using ATmega8Data AcquisitionMar 25, 2009
Atmel 89C2051 prototype boardMicrocontrollerJun 20, 2004
Converter that enables long cable wiring for pyranometerSolarMar 25, 2009
AVR Line Following RobotModelsMar 25, 2009
Isolated Full Duplex RS232C InterfacePCJan 26, 2001
RS232 DB-9 switch to flip between two serial portsPCJun 20, 2004
Simple RS422 Converter for MiniloggerData AcquisitionMar 25, 2009
AT89C2051 real-time controllerMicrocontrollerJan 26, 2001
PIC12C508 Night-light saverMicrocontrollerJan 26, 2001
AT89C2051 Night light saverMicrocontrollerJan 26, 2001
Night light saver using AT89C2051LightingMar 25, 2009
Atmel 8051 Flash Based-Microcontroller ProgrammerMicrocontrollerJan 26, 2001
CMOS control voltage for firing Crydom Soft-Start Motor ModuleControlMar 25, 2009
Solar energy meterSolarMar 25, 2009
Measure solar radiation on an Ubuntu ServerSolarMar 25, 2009
SPI Flash Microcontroller ProgrammerMicrocontrollerMar 25, 2009
AT89Sxx Cheap and Simple Learning BoardMicrocontrollerMar 25, 2009
Sensor to display, built with thermistor, 12-bit ADC, 89S52 and LED displayTestMar 25, 2009
Thermistor Thermometer: LCD versionTestMar 25, 2009
AT89C2051 Digital thermometer and clockMicrocontrollerJan 26, 2001
Tiny 2313 Project Development BoardMicrocontrollerMar 25, 2009
Simple device for connecting serial instrument with RS485 or RS232 to the internetData AcquisitionMar 25, 2009
4-Channel Timer using Atmel 89C4051 and MAX7219 display driverMicrocontrollerJun 20, 2004
Digital timer with 7-segment display and pushbuttonsTimingMar 25, 2009
FAN Thermostat controlled by IR remote controllerControlMar 25, 2009
Car Ignition Coil Driver from 110V ACPowerSep 23, 2009
Laser beam alarm systemLaser 
Amplified zener regulatorPower 
13.5 Watt Power Amplifier using a TL081 opamp and TIP125 / TIP120 power transistorsAmplifiers 
omentary High Voltage Arc Circuit - can be used to Ignite a barbeque or a Gas in a Potato GunMisc 
Simple car battery voltage monitorAutomotive 
Simple BFO metal detector using 2N3906 and 2N3904 transistorsMiscMay 30, 2007
Car Battery Charger, an SCR Design with a 10 Amp ratingAutomotive 
Car Ignition Coil Driver from 12V DC - Can be used as an electric fencePowerSep 23, 2009
Cat or Dog Detector - can be used to control entry on a Cat or Dog DoorMisc 
Battery Charger, Current and Voltage Regulated for Sealed Lead Acid batteriesPower 
Digital Up / Down Counter with 7-segment displayLED 
Delayed Power Circuit using an SCRControl 
LED flasher with "Rising and Falling" BrightnessLEDSep 23, 2009
Ground Fault IndicatorTest 
H-Bridge CircuitControl 
12 Volt Knight Rider LED displayLEDSep 23, 2009
Digital combination lock using pair of CD4013 CMOS chipsAlarmsSep 23, 2009
Low battery cut-off circuit for a car or truckAutomotiveSep 23, 2009
Fish caller circuitMiscSep 23, 2009
Parabolic microphone project circuit (can be used with shotgun directional microphone also)AudioSep 23, 2009
Voltage and current regulated power supplyPowerSep 23, 2009
High current PWM controller based around a 555 timerControlSep 23, 2009
Electronic roulette wheel circuit diagramGamesSep 23, 2009
SCA Adapter - listen to advertisement free background music on FM broadcast radioRFSep 23, 2009
Simple Sine Wave Oscillator including a PCB layoutTimingSep 23, 2009
Solar cell battery charger circuit diagramSolarSep 23, 2009
Using a speaker as a microphone - impedance matching circuitAudioSep 23, 2009
Sound pressure level meterTestSep 23, 2009
Powerful stun gun / taser circuit diagramMiscSep 23, 2009
Simple switching power supply (mains operated)PowerSep 23, 2009
Relatively simple thermostat circuit diagramControlSep 23, 2009
Electric heater thermostatControlSep 23, 2009
TENS Circuit diagram for muscle stimulationMedicalSep 23, 2009
12 Volt Switching Power Supply circuit diagram and PCB layoutPowerSep 23, 2009
Ultrasonic sound detector / snifferMiscSep 23, 2009
Simple voltage booster based on Linear Technologies LT1372, includes PCB designPowerSep 23, 2009
True RMS Watt MeterTestSep 23, 2009
Two transistor FM transmitter circuit diagram and PCB layoutTransmittersSep 23, 2009
Making a bistable from a normal relay, based on coil hysteresisControlJul 21, 2013
Two-button control for dangerous machinesControlOct 05, 2012
Air flow detectorMisc 
Bicycle LED POV (persistence of vision display) LED displayLED 
GSM-900 Mobile Jammer Book (PDF compressed with WinRAR)TelephoneAug 01, 2010
Alkaline battery chargerPowerDec 02, 2002
PIC16F628 controlled FLL (Frequency Locked Loop) VFO for HF (PDF)MicrocontrollerOct 05, 2009
Direct Digital Synthesis VFO for HF Bands - based on Analog Devices AD7009 DDS (PDF)TimingOct 05, 2009
Simple Frequency Reader for conversion VFOsMiscOct 05, 2009
The u-counter, a PIC based programmable frequency meter (PDF)TestOct 05, 2009
Continuous Coverage V.F.O. for H.F. (PDF)TimingOct 05, 2009
Experimental DSB/CW QRP rig for 20 and 40 meter bands (PDF)RFOct 05, 2009
PIC16F84 CW decoder (PDF)MicrocontrollerJul 10, 2002
Simple 40 meters CW QRP Transceiver (PDF)RFOct 05, 2009
20 meters CW QRP Transceiver (PDF)RFOct 05, 2009
Heathkit modulated HeNe laser power supply kit (HK-HI1)Laser 
Easy Xenon DC-DC Converter using LM386Lighting 
Large collection of strobe / photoflash circuit diagramsPhotoSep 01, 2009
Slave Flash Trigger CircuitPhoto 
Car power supply unit for digital projects, small car PCs etcAutomotive 
Atmel AVR ATtiny45 development boardMicrocontrollerJun 28, 2011
RGB pattern generator based on an Atmel ATtiny2313 running at 20MHzVideoJun 28, 2011
Simple RS232 Level Converter based on a MAX232 including Eagle PCB and schematic filesPCJun 28, 2011
AVR thermometer / thermostat based on an Atmel ATtiny2313MicrocontrollerJun 28, 2011
PCB exposure countdown timer based on an Atmel ATtiny2313TimingJun 28, 2011
VCR ping pong gameGamesApr 27, 2004
Video ping pong gameGamesJul 10, 2002
Video Clock SuperimposerVideoJul 10, 2002
Video clock superimposer using PIC16C711VideoApr 27, 2004
Eddie's Composting Loo fan controllerMiscMar 09, 2012
Dual LED dice (available in kit form)Games 
Single LED dice kit circuit diagramGames 
Acceleration Sensor NetworkData Acquisition 
Precision Digital AltimeterData AcquisitionMay 01, 2004
Countdown timer with relayTimingAug 09, 2002
Highly accurate constant current source using LM4140, OP777 and MOSFETPowerMar 17, 2014
MOSFET based H-Bridge controller for DC motorsControlMar 17, 2014
Interfacing a DSLR Hotshoe to an ArduinoMicrocontrollerMar 27, 2014
USB 0-500MHz RF Power Meter based on a AD8307RFFeb 21, 2013
Serial LCD controller using a PIC16F628Microcontroller 
Advanced LED temperature indicatorLEDOct 25, 2014
Simple AM transmitter using a BFW10 FETTransmittersDec 07, 2014
Clap operated remove control for fansControlDec 07, 2014
Dry cell battery chargerPowerDec 07, 2014
Electronics Cricket on boardGamesMar 23, 2015
Electronics Lucky NumberGamesOct 25, 2014
Simple FM receiver based on a TEA5591 ICRFMar 23, 2015
Long Time Period Automatic TimerTimingOct 25, 2014
Microprocessor based home security systemMicrocontrollerOct 25, 2014
PC-based candle ignitor (parallel port based design)PCDec 07, 2014
PC-Based DC Motor Speed ControllerPCOct 25, 2014
Power Supply Resumption Alarm using 555 timerPowerOct 25, 2014
Presure based hit switchControlDec 07, 2014
Sensitive Optical Burglar AlarmAlarmsOct 25, 2014
Simple FM transmitter using a single transistorTransmittersMar 23, 2015
Simple quiz display using 74 series logic chipsGamesMar 23, 2015
Single chip dice using a 4060 chipGamesDec 07, 2014
Solid-state voltage indicator with high voltage cutoutPowerDec 07, 2014
Sound operated music bell using 555 timerAlarmsDec 07, 2014
Stabilized Power Supply With Short-Circuit IndicationPowerOct 25, 2014
Stereo audio simulatorAudioMar 23, 2015
Temperature Indicator Using AT89C52MicrocontrollerDec 07, 2014
Touch operated Band switch for Radio SetMiscOct 25, 2014
Trangular wave generatorTimingMar 23, 2015
Capacitor voltage stepper using 555 timerPowerDec 07, 2014
White / LF noise generatorAudioDec 07, 2014
Wind Sound GeneratorAudioOct 25, 2014
Home Built Laser ProjectorLaser 
Arduino Mega 2560 schematic (PDF) - Arduino R3MicrocontrollerJul 21, 2013
DPA 220 amplifier schematicAmplifiers 
Low impedance microphone amplifierAmplifiers 
DPA 440 amplifier schematicAmplifiers 
Low pass filter for subwooferFilter 
Portable Mixer with high-quality modular design (9V battery powered)Music 
100W audio amplifier including PCB layoutAmplifiersApr 14, 2011
Quadraphonic Amplifier based on pair of LM1877 devicesAmplifiers 
DPA 880 amplifier schematicAmplifiers 
Class-A/AB Amplifier delivering 100W into a 4 ohm loadAmplifiers 
Audio Indicator - monitor a loudspeaker, alarm, or audio source for presence of an audio waveformAudio 
Stereo Audio IsolatorAudio 
Guitar Reverb Effect Version 2Music 
Guitar Reverb PedalMusic 
Voltage Controlled PannerAudio 
25 Watt MOSFET Audio Amplifier using IRF532 / IRF9532 hexfet transistors for output stageAmplifiers 
Large capacitor charge "controllers" (Car Audio)Automotive 
Easy to build DIY 50W amplifier based on ICL8063Amplifiers 
Audio VU Meter based on pair of LM324 quad opampsAudio 
Voice-Over CircuitAudio 
20 Watt Audio Power Amplifier using TDA2005MAmplifiers 
22 Watt Stereo Amplifier using TDA1554Amplifiers 
Two Transistors Audio AmplifierAmplifiers 
10 Watt Audio Amplifier circuit diagramAmplifiers 
Underwater microphone used in a home aquarium to monitor fish soundsAudio 
Speed limit alertAutomotiveJul 05, 2012
Motorcycle AlarmAlarmsJul 05, 2012
Car Alarm and ImmobilizerAlarmsJul 05, 2012
Car Hijack AlarmAlarmsJul 05, 2012
Motorcycle Alarm Number 2AlarmsJul 05, 2012
Motorcycle Alarm Number 3AlarmsJul 05, 2012
Motorcycle Alarm Number 4AlarmsJul 05, 2012
Motorcycle Alarm Number 5 & 6AlarmsJul 05, 2012
Park-Aid - Three LEDs signal bumper-barrier distanceAutomotiveJul 05, 2012
Headlight FlasherAutomotiveJul 05, 2012
Car Voltage Gauge with 7-segment readoutAutomotiveJul 05, 2012
Car Water Temperature Gauge with 7-segment readoutAutomotiveJul 05, 2012
Auto Burglar AlarmAlarmsJul 05, 2012
Automotive Speed IndicatorAutomotiveJul 05, 2012
Simple but reliable car battery tester using LM3914AutomotiveJul 05, 2012
Automotive 12V to +-20V converter (for audio amplifier)AutomotiveJul 05, 2012
Electronic car ignitionAutomotiveJul 05, 2012
Car battery charger with automatic cutoffAutomotiveJul 05, 2012
Automatic Headlight Brightness SwitchAutomotiveJul 05, 2012
Dome Lamp DimmerAutomotiveJul 05, 2012
Light switch using LDRControlJun 26, 2009
Digital Remote ThermometerMiscJun 26, 2009
Fridge door AlarmAlarmsJun 26, 2009
Room Noise DetectorAudioJun 26, 2009
Capacitive SensorMiscJun 26, 2009
Ultra-simple Voltage ProbeTestJun 26, 2009
Emergency Light & AlarmAlarmsJun 26, 2009
Heating System ThermostatControlJun 26, 2009
Touch switch based on CD4011 flip-flopControlJun 26, 2009
Door Alarm circuit diagramAlarmsJun 26, 2009
Mains Remote-Alert - Remotely operates beeper and/or a LED via mains supply lineMiscJun 26, 2009
Low Voltage Alarm for batteries and other volatile DC power sourcesPowerJun 26, 2009
Touch activated switch using CD4011 CMOS NAND gateMiscJun 26, 2009
Voice activated switch (VOX) circuit diagramMiscJun 26, 2009
Everything-that-moves alarm works by inducing eddy currents in living beingsAlarmsJun 26, 2009
Electronic locker digital combination lock circuit diagramAlarmsJun 26, 2009
Electronic Eavesdropping Devices DetectorRFJun 26, 2009
Simple Infa-Red Remote ControlIRJun 26, 2009
IR Remote Control Extender CircuitIRJun 26, 2009
Gate alarmAlarmsJun 26, 2009
Circuit diagram for 5 Zone Alarm SystemAlarmsJun 26, 2009
Miniature Loop AlarmAlarmsJun 26, 2009
Modular Burglar AlarmAlarmsJun 26, 2009
Water Activated AlarmAlarmsJun 26, 2009
Novel buzzer using a relay and transformerAudioJun 26, 2009
Radio Wave AlarmRFJun 26, 2009
Enhanced 5 Digit Alarm KeypadAlarmsJun 26, 2009
Enhanced 4 Digit Alarm KeypadAlarmsJun 26, 2009
Automatic Intruder AlarmAlarmsJun 26, 2009
Single Zone CMOS AlarmAlarmsJun 26, 2009
Travel Touch AlarmAlarmsJun 26, 2009
UltraSonic RadarMiscJun 26, 2009
Cuckoo sound GeneratorAudio 
TRIAC Light DimmerLighting 
LEDs or Lamps Sequencer is versatile modular design with no limits on number of lightsLighting 
Battery-powered Night LampLighting 
Courtesy light circuit diagramLighting 
Brightness Control for small LampsLighting 
12VDC Fluorescent Lamp DriverLighting 
LED Chaser using 4011 / 4017 CMOS chipsLED 
Adjustable Strobe LightLighting 
Fading LEDsLED 
Dancing LEDs circuit diagramLED 
Black Light powered by a 6 volt batteryLighting 
DC Motor Control CircuitControl 
Fan control based on a TL082 opamp and IRF510 power MOSFETControl 
Bicycle back Safety LightLighting 
Simple LASER Transmitter/Receiver using HeNe laser tubeLaser 
LASER Transmitter/Receiver using Pulse Width Modulator (PWM) for 12V / 24V applicationsLaser 
Nocturnal Animals WhiskerMisc 
Seven Component Regulated LED LampLED 
LED Mood LightLED 
13 Color LED Rainbow circuit diagramLED 
Lightning Activated Camera Shutter TriggerPhoto 
Electronic CanaryAudio 
Metronome CircuitMusic 
Sun - Up Alarm that provides an audible alarm when the sun comes up or a dark area is illuminatedAlarms 
Assortment of Siren CircuitsAudioSep 17, 2009
60 LED ClockLED 
Bike Light FlasherLighting 
Simple 120 VAC motor speed controller based on a TRIACControl 
PIC Light Chaser using PIC16C84Microcontroller 
Wire tracerTest 
Flashing neon christmas lightsLighting 
Doorbell for the DeafAlarms 
Insect RepellantMiscSep 17, 2009
220 Volts Flashing LampsLighting 
IR Audio linkIRJul 05, 2012
Wireless IR headphone transmitterIRJun 28, 2009
Wireless IR headphone receiverIRJun 28, 2009
IR illuminator for night-vision tv cameras and scopesIRJun 28, 2009
Infra Red Switch that works with commonly available remote controlsIRJul 05, 2012
Infra Red Remote Control Extender (Mark 1)IRJul 05, 2012
IR Remote Control TesterTestJul 05, 2012
IR Remote Control Extender Circuit (Mark 2)IRJul 05, 2012
IR Remote Control Extender Circuit (Mark 3)IRJul 05, 2012
IR Remote Control Extender Circuit (Mark 4)IRJul 05, 2012
IR Remote Control Extender Circuit (Mark 5)IRJul 05, 2012
Infrared Remote Control that operates on 115 volts ACIRJul 05, 2012
Three channel audio spectrum analyzerAudioOct 21, 2009
Digital Voltmeter using ICL7107TestSep 17, 2009
Triangle / Squarewave Generator using a 1458 dual opampTimingOct 21, 2009
Beeper to find short circuitsTestOct 19, 2009
Voltage follower with 1G ohm input resistance based on LM11 opampPreampOct 21, 2009
Led display digital Voltmeter using ICL7107TestSep 17, 2009
MOSFET transistor testerTestNov 05, 2009
Precision Audio MillivoltmeterAudioSep 17, 2009
Oscilloscope testing module (huntron circuit)TestNov 10, 2009
Voltage Monitor using UA741 operational amplifierPowerOct 19, 2009
Logic probeTestOct 19, 2009
Digital Radar SpeedometerMiscOct 21, 2009
Digital Volume Control based around CD4067 CMOS chipsAudioOct 19, 2009
Electromagnetic Field Probe with Meter Output using an LF351 opampMiscOct 19, 2009
Three-Level Audio Power IndicatorAudioOct 19, 2009
Beat Balance Metal DetectorMisc 
Coil Coupled Operation Metal DetectorMiscNov 10, 2009
Expanded Scale Battery Volt MeterPowerSep 17, 2009
Pulse Reading Logic ProbeTestOct 19, 2009
Stereo Test Tone GeneratorTestOct 21, 2009
Continuity Tester based on 4 x 2N3904 and 1 x 2N3905 transistorsTestOct 19, 2009
Audible Logic Probe based on LM339 operational amplifierTestOct 19, 2009
Single chip digital voltmeter using ICL7129TestNov 05, 2009
Latching Continuity Tester to help find intermittent faults, has quite a few innovative featuresTestOct 19, 2009
Infrared remote control tester using a SFH2030 photodiode and a CA3140 operational amplifierIROct 19, 2009
Linear Resistance MeterTestOct 19, 2009
XTal Tester for testing quartz crystals based on a pair of BC550C PNP transistorsTestOct 19, 2009
Portable GSM900 Cellular Phone JammerTelephoneAug 01, 2010
High Power 800 MHz/AMPS Cellular Phone JammerTelephoneAug 01, 2010
Cellular Phone Jammer. Ver 2 circuit diagramTelephoneAug 01, 2010
Portable AMPS Cellular Phone JammerTelephoneAug 01, 2010
Portable AMPS Cellular Phone Jammer - Dual PurposeTelephoneAug 01, 2010
PCS Phone Jammer circuit diagramTelephoneAug 01, 2010
Portable PCS Cellular Phone Jammer circuit schematicTelephoneAug 01, 2010
PCS Cellular Phone Jammer circuit schematicTelephoneAug 01, 2010
GBPPR Cellular Phone Jammer Exciter schematic diagramTelephoneAug 01, 2010
Cellular Phone Jammer RF Amplifier circuit diagramTelephoneAug 01, 2010
Homebrew P2JBZ-style cellular / mobile phone jammer circuitTelephoneAug 01, 2010
Self-powered Fast Battery-Tester - Tests 1.5 to 15 Volt cellsTestSep 17, 2009
Battery Low Voltage BeeperPowerSep 17, 2009
AA Battery Solar ChargerSolarSep 17, 2009
4 Transistor Tracking TransmitterTransmitters 
AM TransmitterTransmitters 
FM Telephone BugTelephone 
FM Transmitter using two transistorsTransmitters 
AM/FM Simultaneous Transmitter Using Digital ICTransmitters 
Medium range transmitter using pair of 2N3904 transistorsTransmitters 
15 watt FM transmitter circuit diagramTransmitters 
AM TransmitterTransmitters 
Single transistor FM transmitterTransmitters 
Small FM transmitter using SMD componentsTransmitters 
Miniature FM TransmitterTransmitters 
Low Power FM TransmitterTransmitters 
FM Voice TransmitterTransmitters 
Sensitive FM TransmitterTransmitters 
Small FM TransmitterTransmitters 
TV Signal Amplifier covers frequencies from 40MHz to 900 MHzVideoJun 28, 2009
Linear FM 50Watt with BLY90RFJun 28, 2009
Motorized Video Camera MountVideoJun 28, 2009
TV Transmitter - VHF band TV transmitter using negative sound modulation and PAL video modulationVideoJun 28, 2009
UHF Preamplifier covers 450MHz - 800MHz based on MPSH10 / BF180 / BCY90RFJun 28, 2009
60W Linear amplifier using IRF840 power MOSFETRFJun 28, 2009
Video Signal AmplifierVideoJun 28, 2009
Cellular Phone calling DetectorTelephoneSep 17, 2009
Simple Phone Tap circuit diagramTelephoneAug 12, 2009
Telephone Hold Button circuitTelephoneAug 12, 2009
Telephone recorder to record phone conversations automaticallyTelephoneAug 12, 2009
Cellular Phone calling DetectorTelephoneAug 12, 2009
Phone line indicatorTelephoneSep 17, 2009
Isolated Telephone InterfaceTelephoneAug 12, 2009
Telephone Record Control using 2N4360, 2N2222 and 2N2102TelephoneAug 12, 2009
Voice ScramblerAudioAug 12, 2009
Phone In Use Indicator circuit diagramTelephoneSep 17, 2009
Phone "Hold" With MusicTelephoneAug 12, 2009
Voice / Audio Record / Playback CircuitAudioAug 12, 2009
Simple speakerphoneTelephoneAug 12, 2009
High Quality Intercom using LM380 amplifier ICTelephoneAug 12, 2009
Soft Musical Telephone RingerTelephoneAug 12, 2009
Telephone amplifierTelephoneAug 12, 2009
Cut Phone Line DetectorTelephoneAug 12, 2009
Telephone line monitorTelephoneAug 12, 2009
Phone Busy IndicatorTelephoneAug 12, 2009
Ringing Phone Light Flasher using optocoupler and relayTelephoneAug 12, 2009
ADC conversion using ADC0804LCN and 8051Microcontroller 
Build a Tape Linearizer and a Distortion AnalyzerAudioApr 14, 2010
Peak-reading metersAudioJan 26, 2001
Microphone polarity tester circuit diagranTestApr 14, 2010
Audio Spectrum Analyzer and Equalizer DesignsAudioMar 30, 2010
Build A Stereo SynthesizerMusicMay 07, 2010
Electronic Control for DC Motors Using Discrete Bridge Circuits (PDF)Control 
Defeating SCMS on DAY recorders using a Sony CXD2601 chipAudioMay 07, 2010
Bell 202 and CCITT V23 Compatible FSK Modem CircuitPCOct 27, 2009
Strobo Disco Light Using Standard Tube Lamp (TL)Lighting 
Heartbeat Sensor (Tranduscer)MedicalJan 08, 2014
Low Cost Universal Battery ChargerPowerJan 08, 2014
26V-to-5000V DC-DC ConverterPowerJan 08, 2014
Ring-Around LED FlasherLEDJan 08, 2014
Black Light (UV Tube Lamp) InverterLightingJan 08, 2014
15 Channels Cascaded MAX455 Video MuxVideoJan 08, 2014
Digital Encoder Circuit Using Stepper MotorControlJan 08, 2014
30-Khz Bandwidth High Linearity Opto-Isolated AmplifierAmplifiersJan 08, 2014
Three Wire RS232 To RS485 ConverterPCJan 08, 2014
Low-Drift High-Impedance JFET DC VoltmeterTestJan 08, 2014
Telephone Circuit: Music On HoldTelephoneOct 03, 2013
Loud 10-W Car Alarm SirenAutomotiveOct 03, 2013
Missing Pulse Detector Circuit with 555 ICMiscOct 03, 2013
Binaural Synthesizer/Mono to Stereo Converter for Small Speaker/PhonesAudioOct 03, 2013
Fast Charger for Better Lead-Acid Battery LifePowerOct 03, 2013
5 A Constant Voltage-Constant Current RegulatorPowerOct 03, 2013
Voltage Controlled Variable Gain Video AmplifierVideoOct 03, 2013
Tremolo Effect Circuit for Electric Guitar or Other Musical InstrumentsMusicOct 03, 2013
PC Audio Signal Generator Using RS232 PortPCOct 03, 2013
Powerline Carrier System Transmitter for Audio (Music/Speech)AudioOct 03, 2013
Compact 3W BTL Audio Power Amplifier TDA7056AudioOct 03, 2013
CamTrig - A home-made light-operated camera triggerPhoto 
A simple home-made light-operated camera triggerPhoto 
A home-made light-operated camera trigger using the stamp microprocessorPhoto 
Resistor decade boxTestAug 14, 2002
Gameboy MIDI interface circuit schematic and notes on Linux development for GameboyPDAFeb 05, 2010
Octave screamerMusicJan 26, 2001
Atari Punk Console schematicsGamesOct 04, 2010
Build A Roomba Bluetooth AdapterModels 
Chaos generatorMiscJan 26, 2001
Various CNC mill circuit diagrams and other DIY CNC mill informationControlJun 17, 2011
5W Chinese PLL FM Transmitter With LCD Printed Circuit Board (PCB)Transmitters 
Simple test equipment to buildTest 
A Two-Way Morse Practice SetMisc 
Send Morse on your VHF RigRF 
An end-fed antenna, L-match coupler and resistive bridge for HFRF 
Regenerative receiver for the AM broadcast band using two transistorsRF 
Two Valve 40m CW TransmitterTransmitters 
Novel crystal set requires no antenna, earthRF 
80 meter direct conversion receiverRF 
3 - 12 MHz Signal GeneratorTiming 
A compact L-match ATU for portable useRF 
80m ceramic resonator VXO CW transmitterTransmitters 
RF Power Meter for the QRP measures up to 25 wattsTest 
Converter to yune six metres on your two metre receiverRF 
80 Metre DSB TransmitterTransmitters 
High quality AM through your FM stereoRF 
Signal Frequency Beat Frequency OscillatorTiming 
Dip Oscillator for HFTest 
Converter to Hear Amateurs on your FM RadioRF 
RF Actuated Keying MonitorRF 
LF to HF ConverterRF 
CMOS IC 1 kHz Audio OscillatorAudio 
One Valve CW transmitterTransmitters 
1A Variable Regulated Power SupplyPower 
Super 80 ultra-simple SSB receiver for 3.5 MHz a basic superhetRF 
Two Tone Audio OscillatorAudio 
Wide-swing Variable Crystal OscillatorTiming 
Palm PDA based dataloggerPDA 
Traffic light controller with 20-output sequencingModelsSep 10, 2006
4 Photo-Detector circuit with delayed release and bipolar outputAlarmsAug 18, 2009
5 Times Around CircuitModelsSep 10, 2006
8 Photo-Detector Circuit BoardData AcquisitionSep 10, 2006
Fast Electronic Circuit Breaker for Model RailwaysModelsNov 13, 2010
Automatic - Railway Grade Crossing Circuit (2008 design)Models 
Audible Train Approach Warning CircuitModelsSep 10, 2006
Across The Track Infrared DetectorsModelsSep 10, 2006
Automatic Reversing Circuit for Model TrainsModelsNov 13, 2010
Voltage Comparator Information And CircuitsMiscApr 27, 2003
Block Occupancy Detector For DCCModels 
Rail Crossing Diamond Protection CircuitModelsSep 10, 2006
Automatic Railway Grade Crossing FlashersModelsSep 10, 2006
H Bridge Motor Control CircuitsControlJun 09, 2002
Incline Railway Control CircuitModelsJan 01, 2003
Infrared Proximity Detector based on Vishay TSOP4830IR 
LM3909 replacement using discrete componentsLEDFeb 14, 2003
Model Railroad Odometer CarModelsSep 10, 2006
Visible and Infrared Light DetectorsMisc 
Turnout Anti-Derail Protection CircuitsModelsSep 10, 2006
Regulated Power Supply CircuitsPowerSep 10, 2006
Single Traffic Light Driver CircuitModelsNov 13, 2010
Basic Solid State RelaysPowerSep 10, 2006
Unipolar and bipolar stepper motor driver circuits using 74194 and ULN2803ControlNov 04, 2011
Various Transistor Throttles Cicuit SchematicsModelsSep 10, 2006
Three Terminal Regulator Type Throttle (LM350K)ModelsSep 10, 2006
1200 Watt Lamp Dimmer Circuit using Q4015LT combination DiacLightingSep 10, 2006
LM311 Thermostat circuit diagramsPower 
10, 8 And 6 Step LED Circuits (CD4017)LEDSep 10, 2006
5 Second Ramp Generator for Locomotive Sound Card DemonstrationModels 
Transformer Secondary Voltage ReductionPower 
Adding External Meters to DC ThrottlesModels 
Back And Forth - Bidirectional Bipolar Stepper Motor DriverPower 
Grade Crossing Bell Ringer (LM555)Models 
CA4060B Timer CircuitsTimingSep 10, 2006
Train Mounted Camera Battery ChargerModels 
Using Common Cathode Or Anode LEDs As Bipolar LEDsLED 
Timed Uncoupling Ramp Driver (LM555)ModelsSep 10, 2006
Colour Shifting For Bi-Colour LED'sLEDSep 10, 2006
Light Activated Detector Circuit (LM393/LM555)MiscSep 10, 2006
Diode Type Constant Lighting CircuitsLightingSep 10, 2006
High Side Current Monitors (LM358, Zetex - ZXCT-1009)PowerSep 10, 2006
Current Regulators For Light Emitting DiodesLEDSep 10, 2006
DCC To DC - Accessory Power SuppliesModels 
Grouped DCC Block Occupancy DetectorsModelsSep 10, 2006
HIGH or LOW Power Switch For Lights or Small MotorsControlSep 10, 2006
High Impedance VoltmeterTestSep 10, 2006
Incandescent LED CircuitLEDSep 10, 2006
Model Railroad - Infrared Proximity SwitchModels 
Infrared Receiver Module SchematicsIRSep 10, 2006
Various LM555 LED Blinker CircuitsLEDSep 10, 2006
Low Battery Voltage Cutout CircuitsPowerSep 10, 2006
Preselect Twin Coil Switch Machine CircuitPower 
First Across The Line Race Scorer CircuitsModelsSep 10, 2006
School Bus Signals CircuitModelsSep 10, 2006
N.O. Magnetic Reed Switch ON /OFF Circuit (SCR equivalent)Power 
Servo Motor Test Circuit (LM555)Test 
Special Function Timer Circuits (LM555)TimingSep 10, 2006
Team digital - SCR16 - Twin Coil Switch Machine AdapterPower 
LED Out Circuit For Tortoise Switch MachinesModels 
Push Button Motor Control CircuitsControlSep 10, 2006
Timed DC ThrottleModelsSep 10, 2006
Efficient unipolar stepper motor driver (only uses power when it makes a step)Power 
DCC - Zero Stretching Simulator (LM555)ModelsSep 10, 2006
Basic 10GHz / 24GHz gunplexer / gunn diode control circuit (PDF)RF 
10 GHz CW Radar based on a X-band GunnplexerMisc 
Self made data-logger V2.5 (second edition)Data AcquisitionNov 27, 2002
GoldPic 3 Pulse Induction Metal Detector (has electronic kit available)MiscMay 30, 2007
Apple IIe RGB to CGAVideo 
Photodiode primer and interface circuit diagrams including photovoltaic and photoconductive modesMiscMar 04, 2010
Build a PIC controlled DDS VFO, 0 to 6 MHzMicrocontrollerJul 12, 2001
MBC5/CPLD for the GameBoyGamesOct 31, 2002
10W 2M CW transmitter circuit diagramTransmittersJun 19, 2011
50 MHz to 10 MHz receive converterRFJun 19, 2011
17M to 6M transveter circuit diagramRFJun 19, 2011
metre receiverRFJun 19, 2011
Passive grid (tube based) linear amplifierRFJun 19, 2011
T-Match ATU (antenna tuning unit)RFJun 19, 2011
Fourth order Butterworth BPF circuit diagram and design notesFilterJun 19, 2011
Frequency counter based on PIC16F628 and LCD displayTestJun 19, 2011
10MHz GPS disciplined frequency standardTimingJun 19, 2011
Iambic keyer based on a PIC16F84 or PIC16C84MicrocontrollerJun 19, 2011
Chebyshev low pass filter, rolls of at 30MHzFilterJun 19, 2011
PIC18F4550 Development Board including PCB layout suitable for home etchingMicrocontrollerJun 19, 2011
Single transistor receiver for SSB, CW, AM using a VHF dual gate MOSFETRFJun 19, 2011
Multi band SSB transceiver construction projectRFJun 19, 2011
Receiver building blocksRFSep 06, 2001
Digital display and VFO stabiliser using a PIC microcontroller and LCDRFJun 19, 2011
SSB transceiver for 80MRFJun 19, 2011
Simple CW transmitter for 80MTransmittersJun 13, 2011
VHF receiver convertererRF 
Parallel AVR programmerMicrocontrollerMay 01, 2004
Europa30, a 10MHz QRP TXTransmitters 
A Receive Signal DecoderModelsOct 30, 2002
Motor speed controllersControlJun 17, 2003
How to install LED lights to Mini-Z model car (based on PIC12C509)GamesNov 05, 2009
Alternative power source for Magellan GPS receiversPowerMay 01, 2004
PIC16F84 line following robotMicrocontrollerJan 26, 2001
8 x 8 Audio-video switchVideoMar 23, 2003
Commodore 64 24-bit parallel port interface with 8255PCMar 23, 2003
PIC16C505 IR / wireless remote controlMicrocontrollerMar 23, 2003
DIY 2^16 encoder based on PICMicrocontrollerApr 12, 2014
Electronic door codelock (PIC16F84)AlarmsMar 23, 2003
Automatic door opener with PIC12C508MicrocontrollerMar 01, 2001
Full-duplex doorphone with 3 wires connectionMiscMar 23, 2003
Infrared gate for doorIRMar 23, 2003
Infrared circuits for remote controlIRMar 23, 2003
Serial port controller infrared transmitter (PIC16F628)IRMar 23, 2003
Dual light timer based on PIC - Automatically turn off the lights after 10 minutesLightingApr 12, 2014
3-wire serial LCD interface for the PICMicrocontroller 
Learning IR remote control receiver using a PIC16F628IRApr 12, 2014
Low impedance microphone amplifierPreampMar 23, 2003
RS485-like multi-drop bus with half duplex serial protocolMicrocontrollerMar 23, 2003
EPCOS Principles of SAWR-stabilized oscillators and transmitters application notes (PDF)TransmittersApr 12, 2014
Circuit diagrams for 418/433 MHz short-range communication (Elektor Electronics article)RFApr 12, 2014
88 - 108MHz FM audio transmitter / bug circuit diagramTransmittersApr 12, 2014
Circuit diagram for superregenerative receiver built by GE labsRFApr 12, 2014
X10 RF daughter board - receiver circuit diagramRFApr 12, 2014
RX3302 433MHz superregenerative receiver module circuit diagramRFApr 12, 2014
Automicro RX3304 receiver module schematicRFApr 12, 2014
Automicro TM02 high power data transmitter module circuit diagramTransmittersApr 12, 2014
27MHz toy car receiver L4=9 turns, .15mm wire on 4.5mm diameter tunable ferrite coil formerModelsApr 12, 2014
SAW-based 434MHz transmitter schematic with RO2101 1-port SAW resonatorTransmittersApr 12, 2014
Simple VHF video transmitter / video modulator circuit diagram (not FCC approved)VideoApr 12, 2014
500MHz video signal transmitterVideoApr 12, 2014
RF Audio transmitter circuit diagram that operates in the AM broadcast bandTransmittersApr 12, 2014
49MHz walkie-talkie circuit diagram that uses only three transistorsRFApr 12, 2014
Superregenerative 27MHz receiverRFMar 23, 2003
LCD thermometer using PIC16F871Microcontroller 
Electronic irrigation controller based on PICMicrocontroller 
USB digital I/O extender using a PIC18F14K50PCApr 12, 2014
220V live wire-in-wall scannerTestMar 23, 2003
Opendiag OBD-II Schematics & PCB Layout Opendiag OBD-II Schematics & PCB LayoutAutomotive 
G Strain energy absorberMiscJan 01, 2003
Test oscillator that generates sinewaves, squarewaves, and triangle wavesTestFeb 20, 2013
PPMScope DIY oscilloscope with 1MHz sampling rate and Windows softwareTestFeb 20, 2013
'Almost No Parts' 7-segments 12/24 Hours LED clock with PIC 16F84A or 16F628AMicrocontrollerSep 25, 2009
FM Microphone micro-transmitter that is small and sensitiveTransmitters 
Montreal Doppler 3 DF (direction finder) unitRFApr 14, 2011
A PIC-based "TDOA" RDF (radio direction finder) antenna unitMicrocontrollerApr 14, 2011
Construction details for 30 meter rig with superhet receiver and crystal controlled transmitterRFApr 12, 2014
All Discrete Components 40 M transceiver with super-het receiver using no IC'sRFApr 12, 2014
Versatile L tuner for end feed wire antennas that fits in an Altoids tin.RFApr 12, 2014
MMR-40 40 meter rig with SSB (voice) and CW (Morse code) operating modes.RFApr 12, 2014
Battery voltage monitor using an LM358 op-ampPowerApr 12, 2014
KD1JV Digital SWR / Power MeterTestApr 12, 2014
An 80 meter rig for the MAS contest by KD1JVRFApr 12, 2014
A unique PSK transceiver, Version 2 By Steven Weber, KD1JVRFApr 12, 2014
(Fairly) Simple 75M SSB rig with PTTRFApr 12, 2014
AM Short Wave Broadcast Receiver circuit diagramRF 
Low Power Antenna Analyzer and ATU Tuning AidTest 
Voltage boost and buck circuits using Atmel AVR Tiny13V for driving a white LEDLEDMar 09, 2012
Fixed Frequency "Tuner Dipper"Test 
0-14 volt, 0-2 amp current limited variable power supply regulatorPower 
A Variable power supply with adjustable current limiting. 0-14V output up to 5A current.PowerApr 12, 2014
Simple WWV receiver for 10 MHz calibration signalTimingApr 12, 2014
Microcontroller (AT89C2051) based tachometer (PDF)AudioNov 13, 2010
GSM SMS javljalnik ALSMS-01 (page in slovenian )SMS remote control projectControlOct 07, 2009
Singing Christmas tree based on Microchip PIC16F84MicrocontrollerOct 07, 2009
DDS/PLL based VFO synthesizerTimingOct 07, 2009
Universal USB digimode interface supports CAT (Yaesu), CI/V (Icom) and RS-232 (Kenwood) units (PDF)RFOct 07, 2009
50 MHz frequency counter, voltage meter & SWR/PWR indicatorMicrocontrollerJul 12, 2001
Universal frequency counter & voltage meterTestOct 07, 2009
Convert 2m VHF FM PMR transceiver Motorola Radius M110 into an amateur radioRFJun 18, 2003
Simple CW identifier for a FM repeater (PDF)RFOct 07, 2009
Transceiver to PC soundblaster interface for digital operating modes (PSK-31, RTTY, SSTV etc)PCOct 07, 2009
6m SSB & CW QRP transceiverRFOct 07, 2009
80m SSB & CW QRP superhet transceiverRFOct 07, 2009
Transceiver to PC interface with a hardware DTMF detector and galvanic isolation (PDF)PCOct 07, 2009
Pocket sized 20m (30m) CW QRP transceiverRFOct 07, 2009
USB / CAT (CI-V) adapter tested with FT-8900, FTB-9800, VX-7R, VX-7, FT-817 and IC-706MkIIGRFOct 07, 2009
Amateur weather station to APRS interface ALWXI-01MiscOct 07, 2009
Collection of quartz crystal ladder filter circuit diagramsFilterOct 07, 2009
Building a Digital Intervalometer - includes circuit diagram and suggested layoutPhotoMay 09, 2010
Serial LCD Controller using Microchip PIC16F628Microcontroller 
Arduino based motion triggered camera using a PIR sensorPhotoNov 13, 2010
Dynamo Current and Voltage RegulatorPowerSep 21, 2006
Wideband SWR meterRF 
Universal sound and optical slave flash triggerPhoto 
Spring reverb unitAudioJan 26, 2001
Incoming call indicator (ZIP file)TelephoneJan 26, 2001
A 3m (100 MHz) small bug (ZIP file)TransmittersJan 26, 2001
Digital speedometer for cars with 7-segment display of speedAutomotiveJun 28, 2011
PC serial port parastic mode interface for 1-wire DS18S20 and similar 1-wire temperature sensorsPCJun 28, 2011
Homebrew Wired Remote for Canon EOS 350D CameraPhoto 
Dreamcast PC serial adapterGamesOct 23, 2002
How to use a SCART TV as a Monitor for MAME arcade game emulatorGames 
SCA Subcarrier Demodulator for FM broadcast stationsRF 
ESR MeterTestMay 17, 2002
Line Output / Flyback transformer testerTestMay 17, 2002
LED Voltage Indicator BoardLED 
Voice Message Recorder / Player (uses an obsolete voice recorder chip)Audio 
BC547 80M SSB QRP TransceiverTransmitters 
Timer circuit based on a 14536 and 4011 CMOS chips that can be calibrated using a frequency counterTimingJan 31, 2010
Circuit diagram for basic alarm with delayed triggerAlarmsFeb 09, 2010
General purpose portable DC power supply using rechargeable C cellsPowerFeb 05, 2010
PCB board tester and RF detector circuir diagramsTestFeb 09, 2010
Alarm circuit to remind you to turn off your DMM (digital multimeter)TestJan 31, 2010
Circuit to enable cycling a string of Christmas lightsLightingJan 31, 2010
Pseudo car alarm systemAutomotiveFeb 05, 2010
45 to 90Hz hum filter circuit diagramFilterSep 13, 2006
Sound alarm based on LM741 opamp and LM386 amplifierAudioFeb 09, 2010
General purchase audio preamplifier based on pair of 2N2222 transistorsPreampJan 31, 2010
Audible timer that can be used as a cooking timer for roasting peanuts for exampleTimingJan 31, 2010
Wireless alarm FM transmitter moduleAlarmsFeb 09, 2010
Switch debouncer circuits including transistor, CMOS logic and a 555 timer based designMiscJan 31, 2010
Percussion generator circuitsMusicFeb 09, 2010
Bench power supply that allows a number of varying output voltages to be preset. Includes PCB layoutPowerFeb 26, 2010
Small audio amplifier based on LM386AmplifiersJan 31, 2010
Function generator based on 555 timer and three 2N2222 transistorsTestFeb 05, 2010
Interesesting circuits using diodes ideal for education or introductory courses on electronicsMiscFeb 20, 2010
Sequential flashing arrow circuit using a 4017, also includes a PCB layoutLEDFeb 26, 2010
Selection of run circuits to experiment with the 4017 CMOS decade counter chipMiscFeb 26, 2010
Notes on using LEDs and various LED driver circuit diagramsLEDFeb 26, 2010
Multi-trace scope display that allows up to 4 channels to be viewed on a single oscilloscope channelTestFeb 26, 2010
Small circuit and PCB layout for recording to PC Sound Monitor / Pre-ampPCFeb 26, 2010
FM Microphone transmitter / FM buf circuit diagramTransmittersJan 31, 2010
Model Train Diesel & Horn Sound ModuleModelsMar 30, 2010
Magentic phono cartridge phono preamp circuit diagramPreampFeb 05, 2010
Power supply metering circuits for measuring both voltage and currentPowerFeb 09, 2010
Cicuit diagram for super long range microphone for use with a shotgun microphone or parabolic dishAudioFeb 20, 2010
Fuse or line monitor that will check the status of up to six fuses including a PCB layoutAlarmsFeb 20, 2010
Variety of applications using a CMOS 4001 2-input NOR gate including a PCB layoutMiscFeb 20, 2010
Select of interesting electronic circuits that require only a single transistor ideal for educationMiscFeb 20, 2010
Small selection of useful circuitsMiscFeb 09, 2010
Variety of simple motor control circuit diagrams using SCR or TRIACControlFeb 20, 2010
Super mixer with microphone input / amplifier including a PCB layoutAudioFeb 20, 2010
Selection of 14 oscillator circuits include sinewave, audio, logic and LED flashersTimingFeb 20, 2010
Jeopardy game circuit diagram using three CMOS logic chipsGamesFeb 09, 2010
Selection of audio preamplifiers including circuits suitable for battery operationPreampJan 31, 2010
DDS from 1-60 MHz with built-in amplifier and variable output level using Analog Devices AD9851Test 
Ericsson phone to PC serial port interfacePCNov 29, 2002
Network car controller provides functions for remote door locks, headlight reminder, and car finderAutomotiveMay 16, 2010
Emergency power systemPowerMay 16, 2010
Digital bench power supply based on a PIC16F870PowerMay 24, 2010
Candle simulator based on a PIC12F675 microcontrollerLightingMay 16, 2010
Magnetic card reader to PC RS-232 port interface based on a PIC12F675 microPCMay 24, 2010
Cat toy using a PIC12F675 and a small weighted motor to keep your cat amusedGamesMay 24, 2010
Dirt cheap video using a PIC16F819 microcontrollerMicrocontrollerMay 16, 2010
Dremel drill speed controllerControlMay 16, 2010
Talking Egyption frog boxGamesMay 24, 2010
Talking fish hack using a PIC16F819 microcontrollerMicrocontrollerMay 16, 2010
Furby Resurrection - Project that replaces the electronics in a Furby with new custom electronicsGamesMay 24, 2010
PWM Heater fan controller based on PIC12F675ControlMay 24, 2010
Hexbot robot based on a PIC including source code and circuit diagramModelsMay 16, 2010
433MHz super remote control using a PIC12F683 to boost rangeTransmittersMay 24, 2010
Home theater systemAudioMay 24, 2010
Beam robot / insect based on a PIC16F818 microcontrollerModelsMay 24, 2010
Infrared object detector using a PIC12F629 microcontrollerIRMay 16, 2010
Isolated oscilloscope probeTestMay 16, 2010
Telephone line simulator ideal for testing phone interface projectsTelephoneMay 24, 2010
Lithium Ion Battery Charger based on a PIC micro including circuit diagram and source codePowerMay 24, 2010
Marshmallow Bazooka with a PIC12F615 based capacitor discharge ignition systemMiscMay 16, 2010
Colour Organ based on a PIC16F84 microcontroller including schematics and source codeMusicMay 24, 2010
Touch sensistive touchpad based on a PIC16F627A microMiscMay 24, 2010
Self-powered phone messenger based on a PIC16C819 microcontrollerTelephoneMay 24, 2010
Phone call interceptor to stop unsolicited phone callsTelephoneMay 16, 2010
Telephone call screener with voiceTelephoneMay 24, 2010
Remote RF transmitter based on PIC12F675 or PIC12F629TransmittersMay 24, 2010
Remote infrared terminal for projects requiring IR communicationsIRMay 24, 2010
RS-232 to TTL level translatorPCMay 16, 2010
DIY flying saucer / UFO using a PIC microcontrollerGamesMay 16, 2010
Solar charge controller based on a PIC microcontroller including schematic and source codeSolarMay 16, 2010
SD card interface for PIC microcontroller including schematic and source codeMicrocontrollerMay 16, 2010
Function Generator Sine / Triangle / Square / Saw / Burst Sweep Noise based on PIC16F870TimingMay 16, 2010
Circuit monitoring device logs for over 10 days and can log up to 32k events both digital and analogData AcquisitionMay 24, 2010
Superprobe handheld test device based on a PIC16F870TestMay 24, 2010
Speech Synthesizer Development System using a PIC microcontrollerMicrocontrollerMay 16, 2010
Toy car hack to turn it into a synthetic rodentModelsMay 24, 2010
PIC micro programmer that runs under MAC, Win98, XP, Vista, DOS, Linux, etcMicrocontrollerMay 24, 2010
Video switcher to allow monitoring of multiple video cameras using a single monitorVideoMay 24, 2010
Low cost video motion detection using a PIC16F819 and an LM339VideoMay 24, 2010
YoYo enhancement device using a PIC12F629 to provide LED lighting effectsLEDMay 24, 2010
Electric cockroach zapperMiscMay 24, 2010
Programmer PIC16F84,12C50x and EEPROM 24CxxMicrocontrollerAug 14, 2002
Build an inexpensive Hall effect GaussmeterTest 
Design for a slightly more expensive GaussmeterTest 
Home-Built Magnetic LevitatorMisc 
Project for experimenting with magnetic levitationMisc 
Adaptive Windscreen Wiper ControlAutomotiveApr 14, 2003
Portable iPod chargerPDA 
FET based metal detector using MPF102 / J310 BF998 FETsMiscMay 30, 2007
Ultrasound detectorMiscSep 13, 2006
IC tone control preamplifier using single 741 opampPreampJul 03, 2011
1KHz 4th order Butterworth filter using LT1367 quad operational amplifierFilterJul 03, 2011
1.5 volt FM transmitter circuit diagramTransmittersJul 03, 2011
10-30 watt stereo audio amplifier circuitAmplifiersJul 03, 2011
118MHz to 136MHz aircraft receiver circuit diagramRFJul 03, 2011
12V 300W 4 channel car amplifier schematic diagramAutomotiveJul 03, 2011
1300MHz - 1500MHz transmitter with 20 - 50mW output powerTransmittersJul 03, 2011
1300MHz - 1500MHz antenna with amplifier based on two MAR-8 RF amplifiersRFJul 03, 2011
15W mono car amplifier using TA7227PAutomotiveJul 03, 2011
Shortwave received circuit diagramRFJul 03, 2011
Two transistor audio preamplifier with volume controlPreampJul 03, 2011
20KHz Butterworth active filter using Linear Technology LT1124, LT1355 or LT1169FilterMay 25, 2012
2W / 4W audio amplifier using pair of LA4100, LA4101 or LA4102 modulesAmplifiersMay 25, 2012
455KHz oscillator using FET and 455KHz IF transformerTimingMay 25, 2012
6W mono car amplifier using BA521 or BA532 amplifier moduleAutomotiveMay 25, 2012
Basic logarithmic amplifier using op-amp and NPN transistorPreampJul 03, 2011
Beat frequency oscillator for AM/SW radio receiversRFMay 25, 2012
Direct conversion 7MHz receiver using NE602RFMay 25, 2012
Low voltage microphone preamplifier using LM10PreampMay 25, 2012
Micro TV transmistterVideoMay 25, 2012
Mono audio preamplifier using single 2SC732 transistorPreampMay 25, 2012
Relay interface to R/C receiversModelsMay 25, 2012
Small TV transmitter for CCTV observationVideoMay 25, 2012
VCR head amplifier testerTestMay 25, 2012
Video line receiver using AD818VideoMay 25, 2012
Wireless guitar transmitterMusicMay 25, 2012
Wireless microphone using 741 opamp and 2N3904TransmittersMay 25, 2012
WWV receiverRFMay 25, 2012
Casio calculator interface schematicPDASep 10, 2006
Conrad Electronics MM3610D multimeter cable pinoutTestSep 10, 2006
1.5 GHz PLL Frequency SynthesizerRFApr 10, 2014
Tiny EEG interface schematicMedical 
OpenEEG open hardware EEG projectMedical 
Fitting a JTAG interface to an iPAQ 3600PDASep 10, 2006
Diode laser electronic circuits for atom opticsLaser 
Build Your Own Video-Rate 2-photon MicroscopeMiscSep 25, 2009
LED driving and controlling methods including constant current drivers and PWM brightness controlLEDJul 11, 2012
Touch senstor based on Atmel AT90S2313Microcontroller 
VHF/UHF TV modulatorVideoNov 16, 2002
Programming hardware and softrware for 14-bit FLASH PIC microcontrollersMicrocontrollerFeb 25, 2011
Single cell LED flasher with two-year battery life (LM3909 replacement)LED 
Volvo 164 electric fan thermostatAutomotiveFeb 25, 2011
RS232 to RS485 converter schematic to connect PC to RS485 networkPCApr 09, 2010
RS232 serial to USB converter cable circuit schematicPC 
Sony RS-422 ADAT sync cable pinoutMiscSep 10, 2006
Mac to HP48 cable pinoutPCSep 10, 2006
Digital cameras (AGFA, Olympus) to PC (COM) cable pinoutPhotoSep 10, 2006
Garmin Foretrex 101,201, Forerunner 101,201 to Serial DB9 cable schematic pinoutMiscSep 10, 2006
Apple iPod and iPhone dock pinoutPDASep 13, 2006
Palm Pilot, Palm III, V, VII, VIIx, Handera interface port pinoutPDASep 13, 2006
Car OBDII diagnostic interface cable schematic pinoutAutomotiveSep 10, 2006
Car OBD II J1850 PWM, J1850 VPW, ISO-9141 cables schematic pinoutAutomotiveSep 10, 2006
Simple DTMF Repeater Controller using PIC16F84Misc 
LCD clock based on AVR Attiny2313Microcontroller 
Music player built on microcontroller AT91SAM7S256 with ARM coreMusic 
Build a Simple Bat DetectorMiscJan 08, 2014
Various radio control schematicsModels 
Linear constant current source dimmer for a white 24-LED arrayLEDMar 03, 2011
Simple current limiting for LED flashlightsLEDMar 03, 2011
Single-Wire-Telephones for caves and minesTelephoneMar 03, 2011
Transverter for Converting SSB CB to LF for Thru-the-Earth Voice CommunicationsRFMar 03, 2011
A simple and inexpensive laser power meter (PDF)LaserFeb 21, 2013
101 AT Keyboard to ASCII Decoder using 68HC705J1A MCUMicrocontrollerJan 26, 2001
Traffic light controller using an Arduino microcontrollerLightingAug 26, 2010
Simple ADS-B aircraft transponder decoder based on a PIC18F2550 microcontrollerRFDec 09, 2010
PIXpand - TI calculator to Playstation memory card interfaceMicrocontrollerJul 12, 2001
Constant current LED driver schematic using a pair of BC547 transistorsLEDJul 11, 2012
Simple laser communicatorLaserJun 09, 2002
PIC 18 programmer (PIC18F458, PIC18F452, PIC18C252, PIC16C745, PIC18F6620, PIC18F6720)MicrocontrollerJun 06, 2003
Game boy camera PC serial interfacePCSep 13, 2006
Build a synchronous clock locked to the mains frequencyTimingAug 18, 2009
Simple Class A Amplifier - 10W audio outputAmplifiersJan 22, 2010
Better Volume (and Balance) control circuit diagramsAudioApr 14, 2010
Low Noise Microphone PreamplifierPreampJun 04, 2010
Bridging Adapter For Audio Power AmplifiersAudioJan 29, 2010
Audio MillivoltmeterTestApr 14, 2010
'A' Weighting Filter For Audio MeasurementsFilterSep 13, 2006
Simple surround sound decoder circuit schematicAudioApr 14, 2010
Stereo Width ControllersMusicMay 07, 2010
Power Amplifier Clipping Indicator Circuit DiagramAudioJan 29, 2010
Collection of phono preamplifier circuitsPreampApr 21, 2010
Digital Delay Unit For Surround SoundMusicMay 07, 2010
100W Guitar Amplifier Mk II circuit diagramMusicJan 29, 2010
Parametric And Sub-Woofer EqualiserAudioApr 14, 2010
High Quality Audio MixerAudioMar 17, 2010
Simple Car Preamplifier and Artificial EarthPreampJan 29, 2010
Loudspeaker Protection and MutingAudioJan 29, 2010
Spring Reverb Unit For Guitar or KeyboardsMusicApr 14, 2010
Audio Signal Detecting Auto Power-On UnitControlMar 30, 2010
Soft-Start Circuit For Power AmpsAmplifiersMar 30, 2010
Mains Power Load Sensing Automatic SwitchControlMar 30, 2010
Thermo-Fan to keep your amplifier or other equipment coolControlMar 30, 2010
Guitar Vibrato Unit Circuit DiagramMusicApr 14, 2010
Microphone Circuit Test OscillatorTestApr 14, 2010
Distortion analyser circuit diagramTestApr 14, 2010
VU And PPM Audio MeteringAudioMay 07, 2010
Variable Amplifier ImpedanceAmplifiersMar 30, 2010
The ESP SIM (Sound Impairment Monitor)TestApr 14, 2010
Linkwitz Cosine Burst GeneratorTestApr 14, 2010
Multiple Feedback Bandpass FilterFilterNov 01, 2002
High quality audio preamplifier (OPA2134)PreampSep 13, 2006
Automatic Charger for Battery Operated Hi-Fi PreampsAudioJun 17, 2003
Capacitance to Voltage conversionMisc 
LED dice project based on 555 timer and CD4017 decade counterGames 
CMoy pocket headphone amplifierAmplifiers 
Biasing Op-Amps into Class AMiscJan 01, 2003
Laser high-voltage power supplyLaserOct 06, 2006
THE FOX - 40 milliwatt transmitterTransmittersApr 14, 2011
THE FOX 750 - 750 milliwatt transmitterTransmittersApr 14, 2011
Active RF antennuatorRFApr 14, 2011
FOX BOX - Transmitter controllerTransmittersApr 14, 2011
Amplified field strength meter / RF snifferTestApr 14, 2011
THE FOX - 250mw transmitter with timerTransmittersApr 14, 2011
Simple Time-Difference-Of-Arrival RDFRFApr 14, 2011
555 Time-Difference-Of-Arrival RDFRFApr 14, 2011
PIC-Bot II using Microchip PIC16LF84Models 
Arduino MIDI interface (Arduino MIDI Drum Kit and Spooky Sound Trigger)MusicAug 26, 2010
Solar robotsSolarNov 16, 2002
Bleeper box for time referenceMiscMay 01, 2004
3 in one tester (audio, tone generator, diode/circuit tester)Test 
50MHz converter project based on a NE602/SA602/NE612RF 
AF variable frequency generator using 555 ICTiming 
Regulatable audio amplifier using a 741opampAudio 
HF/6M Antenna Tuner Preselector and Antenna SwitcherRF 
Bass EQ pre-amp correction for high impedance ceramic crystal pickupAudio 
300/1200 baud BAYCOM MODEM (revision and improved)PC 
Direct Crystal radio receiver examplesRF 
Crystal switcher using diodesTiming 
MW Enhanced Crystal Receiver using 741 ICRF 
455 Khz MF to AF converter used for DRM reception in a Yaesu FRG-100 receiverRF 
Emergency light flasher schematicLighting 
Sensitive LW/MW/SW Shortwave general coverage receiverRF 
HAMCOM (SSTV, RTTY, FAX...) modem using PC-speaker for TXPC 
10 meter (28MHz) band RF amplifierRF 
12 watt audio amplifier with tone using TDA1020Audio 
5 watt audio amplifier using TDA1010Audio 
Low frequency / audio frequency dB output meterAudio 
Basic low frequency preamplifier circuitsPreamp 
Microphone pre-amp with high emphasisPreamp 
MW/SW Radio receiverRF 
Bipolar transistor RF mixerRF 
IC oscillator 1...30MHz using 74LS04 chipTiming 
Simple AF-oscillator / signal generator using pair on 2N2222 transistorsTiming 
HF/VHF mini portable antenna tunerRF 
Microphone preamp for portable transceiversPreamp 
Wideband VHF/UHF/SHF 22dB RF preamp with MAR-6 or MAR-8 (MSA-0885)RF 
PTT and/or soundcard interfacePC 
PTT and soundcard interface for the TM255/455PC 
HF 10 watt amplifier for 18MHz using a 2SC1969/2SC1944 transistorRF 
RF Power meter / dummy loadRF 
HAMCOM (SSTV, RTTY, FAX...) modem using serial audio for TXPC 
HAMCOM & SoundCard MODEM using serial- or soundcard audioPC 
SWR bridge covering HF to VHFRF 
Active bandpass filter with TDA2320AFilter 
1 Watt audio amp using a TDA7052Audio 
TM-441 9600bps packet modificationPC 
1 Watt AM transmitter for the 10 meter band (28MHz)Transmitters 
12-meterband QRP AM oscillator transmitter using a 2N2219 transistorTransmitters 
500mW AM transmitter for the 20 meter band (14MHz)Transmitters 
VHF 6 Meterband RF amplifierRF 
HF/VHF portable antenna tunerRF 
90S2313 AVR Robot BoardMicrocontrollerMay 01, 2004
A selection of robotics projectsModelsJun 09, 2002
Digital clock based on 74 series logicTiming 
LH0032 video amplifierVideoOct 24, 2002
LM359N video amplifierVideoOct 24, 2002
ATmega8 based TNC with GPS and WX supportMicrocontrollerMar 27, 2009
Atmel AVR 90s2313 based POCSAG encoder (ZIP file)MicrocontrollerMar 27, 2009
Atmel 90s2313 based TNCMicrocontrollerMar 27, 2009
ATmega48 based Nixie ClockMicrocontrollerMar 27, 2009
POCSAG encoder/decoder (Zip file)MicrocontrollerJul 10, 2002
360W RMS into 8 ohms or 550W RMS into 4 ohm audio power amplifierAmplifiersMar 17, 2010
Simple alarm with telephone dialler interfaceTelephoneMar 27, 2009
In-circuit electrolytic capacitor checkerTestMar 27, 2009
Logic probe with pulserTestMar 27, 2009
Telephone line simulatorTelephoneMar 05, 2001
Making your own RS-60E3 Remote Control for Canon EOS camerasPhoto 
Home made PBX / PABXTelephoneJun 17, 2003
Headphone amplifier based on 12AX7 tubesAmplifiers 
Two nixie display clockTiming 
Pocket Ignignokt LED displayLED 
VFD (vacuum flourescent display) clockTiming 
Single-digit Nixie clockTiming 
Oscilloscope CRT ClockTiming 
Weston Voltmeter ClockTiming 
Using a PC power supply as a benchtop power supplyPC 
Digibox interface circuit diagramIRAug 09, 2002
Six-channel Mixer and AmplifierAudioJan 31, 2003
Audio Signal SourceAudioOct 30, 2002
Random noise generatorMiscJan 26, 2001
Analog pulse counterMiscAug 12, 2001
Analog opto-isolatorMiscAug 12, 2001
Voltage controlled amplifierAudioAug 12, 2001
Current loop interfaceControlAug 12, 2001
Audio graphic equaliserAudioAug 12, 2001
Intercom preampPreampAug 12, 2001
Electric field & leakage detectorTestAug 12, 2001
Pulse width modulators (PWM)MiscAug 12, 2001
30W ultra-low distortion audio power amplifierAmplifiersJan 22, 2010
Pulse width to voltage converterMiscAug 12, 2001
Ultrasonic remote control & alarm systemAlarmsAug 12, 2001
Grand Cherokee Off-Highway LightsAutomotive 
Flashing LED circuit using 555 timerLEDJul 03, 2011
Engine control unit schematicsAutomotiveNov 16, 2002
3 Channel Spectrum AnalyzerAudioSep 01, 2009
3 Watt FM Transmitter circuit diagramTransmittersSep 01, 2009
6V to 12V ConverterPower 
AC Motor Speed ControllerControlSep 01, 2009
Aircraft Radio Communications ReceiverRFSep 01, 2009
Air flow detector using an incandescent lamp to detect airflowMisc 
Wire Loop Alarm using 4001UBE Quad NOR GateAlarmsSep 01, 2009
Circuit diagram for 8 watt audio ampAmplifiersJan 26, 2001
22 Watt Audio Amplifier using TDA1554 two channel audio amp chipAmplifiersSep 01, 2009
50 Watt Amplifier circuit diagramAmplifiersSep 01, 2009
Fantastic Atom ExpanderLEDSep 01, 2009
Car Alarm Arming Horn Beep CancellerAutomotiveSep 01, 2009
Black LightLightingSep 01, 2009
Portable CD Player Adapter For CarAutomotiveSep 01, 2009
Car Battery ChargerAutomotiveSep 01, 2009
Automatic 12V Lead Acid Battery ChargerPowerSep 01, 2009
LED ChaserLEDSep 01, 2009
Simple Two Speed Contactor DC Motor ControllerControlSep 01, 2009
Digital Keypad Combination LockAlarmsSep 01, 2009
Computer Controlled Frequency Counter/Logic ProbePCSep 01, 2009
Simple Colour OrganMusicSep 01, 2009
7 Segment LED CounterLEDSep 01, 2009
Crystal RadioRFSep 01, 2009
Circuits to computerize your room/housePCSep 01, 2009
TRIAC Light DimmerLightingSep 01, 2009
12VDC Fluorescent Lamp DriverLightingSep 01, 2009
FM Transmitter with range of about 300 feetTransmittersSep 01, 2009
Guitar Fuzz EffectMusicSep 01, 2009
Automatic Headlight Brightness SwitchAutomotiveSep 01, 2009
Solid State Tesla Coil/High Voltage GeneratorPowerSep 01, 2009
Simple Parallel (Printer) Port InterfacePCSep 01, 2009
12V to 120V Inverter circuit diagramPowerSep 01, 2009
Infa-Red Remote ControlIRSep 01, 2009
IR Remote Control JammerIRSep 01, 2009
LASER Power SupplyLaserSep 01, 2009
LASER Transmitter/ReceiverLaserSep 01, 2009
LED ThermometerLEDSep 01, 2009
Simple Lie DetectorMiscSep 01, 2009
Light/Dark Detector drives a relayControlSep 01, 2009
Low Voltage AlarmMiscSep 01, 2009
Video Stabilizer/MacroVision RemovalVideoSep 01, 2009
FET Audio MixerAudioSep 01, 2009
Microphone MixerAudioSep 01, 2009
Pulse Width Modulation DC Motor ControllerControlSep 01, 2009
8 Note Tune PlayerMusicSep 01, 2009
Colour (Sound) OrganMusicSep 01, 2009
Ringing Phone Light FlasherTelephoneSep 01, 2009
Phone Busy IndicatorTelephoneSep 01, 2009
FM Telephone BugTelephoneSep 01, 2009
Cut Phone Line DetectorTelephoneSep 01, 2009
Simple Phone Tap CircuitTelephoneSep 01, 2009
Telephone Hold ButtonTelephoneSep 01, 2009
Telephone RecorderTelephoneSep 01, 2009
Simple Polarity TesterTestSep 01, 2009
Water Detector With Sump/Bilge Pump ControllerControlSep 01, 2009
Pine Racecar Victory JudgeGamesSep 01, 2009
Op Amp RadioRFSep 01, 2009
Rain DetectorMiscSep 01, 2009
Time Delay RelayControlSep 01, 2009
Time Delay Relay IIControlSep 01, 2009
Remote Telephone Bell RingerTelephoneSep 01, 2009
Simple Servo Controller using 555 TimerControlSep 01, 2009
Flash Slave TriggerPhotoSep 01, 2009
Stepper Motor Controller using 4027 flip-flop and 4070 XOR gateControlSep 01, 2009
Mono To Stereo Synthesizer / SimulatorAudioSep 01, 2009
Electronic StethoscopeMedicalSep 01, 2009
Strobe lightLightingJan 26, 2001
Adjustable Strobe LightLightingSep 01, 2009
Basic Power SupplyPowerSep 01, 2009
High Current Power SupplyPowerSep 01, 2009
Dual Polarity Power SupplyPowerSep 01, 2009
High Voltage High Current Power SupplyPowerSep 01, 2009
Transformerless Power SupplyPowerSep 01, 2009
Fixed Voltage Power SupplyPowerSep 01, 2009
Wireless Auto TachometerAutomotiveSep 01, 2009
Tone Control using TDA1524A Tone Control ICAudioSep 01, 2009
Simple Transistor OrganMusicSep 01, 2009
Touch Switch using 4011 CMOS NAND Gate ICControlSep 01, 2009
Video Activated RelayVideo 
Voltage Inverter using 555 TimerPowerSep 01, 2009
Voltage Inverter using LM380 audio amplifier ICPowerSep 01, 2009
Digital Volume Control using DS1669 Digital Pot ICAudioSep 01, 2009
Sound Level MeterAudioSep 01, 2009
89C2051 microcontroller programmerMicrocontroller 
JFET Bass PreampAudio 
Dual power supplyPowerJan 31, 2003
Magnetic levitation deviceMiscAug 14, 2002
Tesla power receiverMiscJan 06, 2002
Class B series modulatorRF 
The KD2BD Pacsat ModemPCJul 10, 2002
SHARP palm-top/hand-held to RS232 serial converterPDA 
1.9 Kilojoule Coil GunMiscNov 16, 2010
20kV Digital High Voltage MeterTestNov 16, 2010
Build your own radio controlled switch from a cordless telephoneTelephoneNov 16, 2010
A spark throwing tesla coil made entirely of garbageMiscNov 16, 2010
Measuring Acceleration Using a PIC Microcontroller (ADXL202 + PIC16F84A)MicrocontrollerJan 09, 2010
PIC serial communications tutorial, includes circuit diagram and PIC16F84 assembler codeMicrocontrollerJan 09, 2010
Eight simple power supplies for your workbench (mainly vacuum tube based)TestApr 10, 2014
Build a Crystal Set (simple AM radio receiver)RFApr 10, 2014
Filter Choke AnalyzerTestApr 10, 2014
Vacuum Tube Grid Leak Detector: Needs an AmplifierTestApr 10, 2014
A Load Box for testing power suppliesTestApr 10, 2014
Low resistance adapter for a DMM (digital multimeter)TestApr 10, 2014
Vacuum Tube Plate Detector: Needs an AmplifierTestApr 10, 2014
Precision Frequency Control for AM Radios - A Frequency Synthesized Local OscillatorRFApr 10, 2014
Miniature SWR / RF power meter circuitTestFeb 15, 2014
Home Brew Compass SensorData AcquisitionApr 27, 2003
Higher Order Analog Butterworth Filter Designs, includes on-line filter calculatorFilterJan 16, 2010
SWTP PR-40 Printer Interface SchematicsPCSep 10, 2006
Interfacing Sony control stick to EmpegGamesJun 09, 2002
Negative voltage generatorPowerAug 12, 2001
Basic Homebuilt Discrete DTL gate circuits (Diode Transistor Logic)Misc 
Electronic shutter release with ultrasonic remote controlPhoto 
Lazer Tag Equipment ModificationsMiscMar 23, 2003
A Serial Infrared Remote ControllerPCJan 26, 2001
Driving high-power loads with a microprocessorMicrocontroller 
Control your camera (Canon DSLR) with your Palm PDAPhoto 
Simple 10 bit DAC for the Arduino using TLC274 opampMicrocontrollerJun 07, 2011
Connect a NTC with a wheatstone bridge to a normal AD-InputData Acquisition 
IDE interface to a Microchip PIC16F877 microcontrollerMicrocontroller 
Inexpensive APRS Weather StationMiscAug 14, 2002
1381 solar engineSolarNov 16, 2002
Collection of BEAM robot circuitsModelsSep 01, 2009
Walking robotModelsAug 14, 2002
Computerized Shutter Control of Canon DSLRsPhoto 
Binary clock using LED matrix to display a binary clock with 6 digits of 4 binary bits eachTiming 
Making an LM35 temperature recorder (based on PIC12F675) - logs to EEPROMData Acquisition 
Schematics and C code for a PIC frequency counter operating up to about 50 MHz (7 segment)Test 
Universal Serial Infrared ReceiverIR 
Schematics and C code for a 0-5V PIC LCD volt meterTest 
Driving led display matrix from a PIC microLED 
Schematics and C code for a PIC frequency counter operating up to about 50 MHz (LCD)Test 
PIC sonar (ultrasonic) range finding project with seven segment display using PIC microMicrocontroller 
A Real Time Clock IC (DS1307) project using the PIC microMicrocontroller 
PIC Serial LCD project - An RS232 serial LCD interface using a standard HD44780 LCDMicrocontroller 
Stepper motor driver using PIC12F675 that offers serial port command interfaceControl 
Stepper motor driver using PIC12F675Control 
Making an LM35 temperature recorder (based on PIC12F675) - serial outputData Acquisition 
Infrared remote control with intervalometer function for Nikon camerasPhoto 
IR Remote Control for Nikon cameras, standard versionPhoto 
Not So Tiny Power Meter - Measures power consumption for entire apartment Not So Tiny Power MeterTestFeb 21, 2013
Accelerometer with microcontroller and displayData Acquisition 
Using a 555 Timer as an A/D converterData Acquisition 
Serial cable for Casio QV-200 digital cameraPhoto 
Locomotive signal braking moduleModels 
H-Bridge Motor Control with Power MOSFETSControlMar 23, 2015
Connect a Serial LCD Display to Raspberry PiMicrocontrollerMar 23, 2015
DSP-RDF Doppler Radio Direction Finder circuit schematic - complete kit availableRFApr 14, 2011
Sea & Sea TTL (Motormarine II, SX-1000) Flash Interface (underwater photography flash)PhotoSep 25, 2009
White LED Drive CircuitLED 
Solar Powered Garden Light with PCB layoutSolarFeb 25, 2011
Low Power PLL FM Transmitter based on LMX1601 and Atmel ATtiny2313 or AT90S2313 microcontrollerTransmitters 
Simplest LED Flasher Circuit using a 2N2222 transistor Simplest LED Flasher Circuit ledLED 
White LED StroboscopeLEDFeb 25, 2011
4th Order Butterworth filter schematic and calculatorFilterJan 16, 2010
Wave Multiplier for music synthesizersMusicApr 27, 2003
Infinite melody for music synthesizersMusic 
Nikon Coolpix 950 / 990 / 995 Flash-adapterPhotoSep 25, 2009
Digital clock that receives and displays the time from the Rugby MSF radio transmission (PIC16F877)Timing 
Remote shutter (or 'cable release') for SLR and DSLR camerasPhoto 
Transistor based single zone intruder alarmAlarms 
CMOS single zone intruder alarmAlarms 
Automatic Intruder Alarm - a simple single-zone burglar alarm circuit based on a 4011 quad NAND gateAlarms 
Hijack alarmAutomotive 
Two-component metal detector using a 4093Misc 
Simple temperature regulated FAN speed controllerControl 
RS-232 to TTL TranslatorMicrocontroller 
Car acceleration meterAutomotive 
Serial port I/O interface using AVR microcontrollerMicrocontroller 
150W audio amplifier that's cheap to build using TIP142 / TIP147 Darlington power transistorsAmplifiers 
Infrared motion detector circuitIRNov 13, 2010
LED based transistor tester LED based transistor testerTestOct 05, 2012
Electronic Nicad glow plug driverGamesApr 27, 2003
A Scenix (and PIC) ProgrammerMicrocontrollerJan 26, 2001
Induced voltage sensor delta-peak trigger for coilgunMisc 
Open loop pulse trigger module for coilgunMisc 
Optical speed trap to measure the the velocity of the projectileMisc 
Optical trigger module for coilgunMisc 
Power MOSFET module for coilgunMisc 
Three stage induced voltage triggered coilgunMisc 
Thyristor fired coilgun circuit diagramMisc 
KITT (from Knight Rider) Car scanner using incandescant lampsAutomotive 
Magnetic levitation project from Electronics Now, February 1996Misc 
LNS Technologies Levitator Kit circuit diagramMisc 
Magnetic levitation project from Popular Electronics, May 1966Misc 
Magnetic levitation project from Popular Electronics, May 1989Misc 
Barry's magnetic levitation projectMisc 
Barry's Coilgun Mark I circuit diagramsMisc 
Barry's Coilgun Mark II circuit diagransMisc 
Barry's Coilgun Mark III circuit diagransMisc 
Barry's Coilgun Mark IV circuit diagransMisc 
Circuit diagram for Coilgun Pistol Pskov 1100Misc 
MMC to PIC16F876 circuit diagramMicrocontrollerJun 18, 2003
Three electronic circuit diagrams for thermal controllers including linear and PWM controlControl 
Circuits for interfacing microcontrollers to a wide number of real-word interfacesMicrocontroller 
Crest Audio LT Series LT100, LT1500 and LT2000 Schematic Set - class D amplifier (PDF)AmplifiersMar 17, 2010
50O Load and Power MeterRFFeb 21, 2013
Simple Audio Tone Control CircuitAudioFeb 21, 2013
TTL pulse counter/logic probeTest 
General purpose ISA interface card for PCPC 
PC ISA Card Random Number GeneratorPC 
Hardware Random Number Generator with an SX microcontrollerMicrocontroller 
MIDI cable for Sound Blaster cardsPC 
PC ISA board containing a Z80 microprocessor (coprocessor card)PC 
8088 maximum mode SBCMicrocontrollerNov 16, 2002
External antenna for the GPS-38, Magellan 2000, or Eagle Explorer GPS receiversRFMay 01, 2004
EZ80 single board computer schematic (Z80)MicrocontrollerApr 27, 2003
8051 Development System Circuit Board circuit diagramMicrocontrollerJun 20, 2004
Inexpensive infrared reflectometerIR 
Sallen-Key Low Pass Filter Calculator (handles Butterworth filters, Bessel filters and Chebychev)FilterJan 16, 2010
Multi-User Jeopardy Game (Fastest Finger First)GamesOct 06, 2006
Commodore RF modulatorVideoJan 01, 2003
Shadow activated (or hand wave) motion detectorControl 
Constant current LED driver circuit using LM334 plus a transistorLEDJul 11, 2012
Laser light output intensity meterLaserOct 06, 2006
175KHz inductive pulse transmitter (PDF)TransmittersJan 26, 2001
175KHz inductive pulse receiver (PDF)RFJan 26, 2001
1-line telephone status indicator powered from a 3V battery (PDF)TelephoneJan 26, 2001
1uS light pulse descriminator plus F to V converter (PDF)MiscJan 26, 2001
1.5V LED flasher B (PDF)LEDJan 26, 2001
200-400 MHz voltage controlled oscillator (PDF)RFJan 26, 2001
20MHz VCSEL 3mW laser test circuit (PDF)LaserJan 26, 2001
20MHz laser light detector (PDF)LaserJan 26, 2001
Broadband 2MHz optical fiber receiver (PDF)MiscJan 26, 2001
Line in use indicator that handles two independent phone lines (PDF)TelephoneJan 26, 2001
3KHz low-pass filter plus audio amp (PDF)FilterJan 26, 2001
Low current LED flasher (PDF)LEDJan 26, 2001
Pushbutton one-shot and latch (PDF)ControlJan 26, 2001
Modulated light receiver circuit (PDF)MiscJan 26, 2001
Micro-power 40KHz burst laser diode driver (PDF)LaserJan 26, 2001
40KHz light receiver (PDF)IRJan 26, 2001
40KHz laser burst detector (PDF)LaserJan 26, 2001
40KHz TV-VCR repeater (PDF)IRJan 26, 2001
4-line telephone status indicator that is polarity independent (PDF)TelephoneJan 26, 2001
1uS light pulse receiver plus post amp (MISC)MiscJan 26, 2001
Broadband 5MHz optical fiber receiver (PDF)MiscJan 26, 2001
5W Fluorescent light intensity modulator (PDF)LightingJan 26, 2001
Line powered 60Hz clock generator (PDF)TimingJan 26, 2001
High-speed 75MHz light receiver (PDF)MiscJan 26, 2001
Micro-power pulse generator (PDF)TimingJan 26, 2001
1.5V LED flasher A (PDF)LEDJan 26, 2001
Flashing LED advertising badge (PDF)LEDJan 26, 2001
Flashing LED advertising badge (PDF)LEDNov 17, 2002
Honey Bee counter (PDF)Data AcquisitionJan 26, 2001
Power reminder beeper (PDF)PowerJan 26, 2001
Very loud beeper (PDF)AudioJan 26, 2001
Darkroom camera shutter timerPhotoJan 26, 2001
Capacitance type liquid level measurement (PDF)Data AcquisitionJan 26, 2001
Unplugged power cord alarmPowerJan 26, 2001
Modulated laser diode tester (PDF)LaserJan 26, 2001
Divide by 1.5 counter (PDF)TimingJan 26, 2001
Door knob alarm (PDF)AlarmsJan 26, 2001
Basement doorbell beeper (PDF)MiscJan 26, 2001
Time to dust indicator - battery powered dust indicator (PDF)MiscJan 26, 2001
Charge coupled bi-directional power MOSFET relay (PDF)ControlJan 26, 2001
Finger touch activated switch (PDF)ControlJan 26, 2001
High-output square wave generator (PDF)TimingJan 26, 2001
1W Fluorescent lamp night light (PDF)LightingJan 26, 2001
Water seepage alarm (PDF)AlarmsJan 26, 2001
Machine vibration triggers hour meter (PDF)ControlJan 26, 2001
LASER/LED light output intensity meter (PDF)LaserJan 26, 2001
Solid state relay (PDF)ControlJan 26, 2001
Digital noise generator (PDF)AudioJan 26, 2001
D Flip-flot one-shot circuits (PDF)TimingJan 26, 2001
Low-power optical interrupter (PDF)MiscJan 26, 2001
Micro-power over temperature alarm (PDF)AlarmsJan 26, 2001
Machine power loss beepter (PDF)PowerJan 26, 2001
Simple nitrogen spark generator (PDF)MiscJan 26, 2001
Pulsed LED test circuit (PDF)LEDJan 26, 2001
Low battery voltage flasher (PDF)LEDJan 26, 2001
Video signal edge enhancementVideoJan 26, 2001
Long-period watchdog timerMicrocontrollerJan 26, 2001
Line-powered Xenon flash transmitter (PDF)ControlJan 26, 2001
9V Xenon photoflash controller (PDF)ControlJan 26, 2001
Series Notch Fliter Designer / Calculator (displays circuit diagram after calculation)FilterJan 16, 2010
Cellular Phone calling DetectorTelephone 
7MHz QRP transmitterTransmittersJul 09, 2002
Tone display systemAudioOct 30, 2002
Tube amplifierAmplifiersAug 14, 2002
Infrared proximity detector based on Microchip PIC12C508 or PIC12C509IRAug 17, 2009
Simple NiCad battery charger using LM317PowerAug 17, 2009
Quickie servo tester for testing servo motors (based on Atmel AT90S2343)TestAug 17, 2009
Low cost gyro / accelerometer combo sensorData AcquisitionAug 17, 2009
Analog Filters for Data Conversion (ADC filter)FilterJan 16, 2010
Simple DIY BFO metal detectorMiscJun 27, 2010
Transducer AmplifiersData Acquisition 
Equivalent circuit and SPICE model of 555 timerTimingApr 11, 2011
ADC Input Driver DIFFERENTIAL to DIFFERENTIALData AcquisitionApr 11, 2011
ADC Input Driver DIFFERENTIAL to SINGLE-ENDEDData AcquisitionApr 11, 2011
ADC Input Driver FULLY DIFFERENTIAL AMPLIFIERData AcquisitionApr 11, 2011
ADC Input Driver SINGLE-ENDED to DIFFERENTIALData AcquisitionApr 11, 2011
ADC Input Driver SINGLE-ENDED to SINGLE-ENDEDData AcquisitionApr 11, 2011
Op-Amp Current Source with Floating Load including SPICE simulationPowerMar 26, 2011
H-Bridge Power Amp circuit diagram and SPICE simulation filesAmplifiersJan 17, 2011
Op Amp Comparator with Hysteresis with SPICE simulationMiscMar 26, 2011
Op Amp Precision Half-wave Rectifier including SPICE simulationMiscMar 26, 2011
Op Amp based PID Controller circuit with SPICE simulationControlMar 26, 2011
Op Amp Triangle-Wave Generator circuit diagram and SPICE simulation filesTimingJan 17, 2011
RC Low-Pass Filter with Op Amp Buffer (single pole filter) with SPICE simulation filesFilterJan 17, 2011
Single-Supply AC Inverting Op Amp amplifier with SPICE simulationMiscMar 26, 2011
Sallen-Key Low-Pass Filter (Double-Pole) with SPICE simulation filesFilterJan 17, 2011
Wien Bridge Oscillator with SPICE simulationTimingMar 26, 2011
Basic Audio Amplifier including a SPICE modelAmplifiersApr 11, 2011
Thermostat node schematicData AcquisitionOct 31, 2002
No-Hum Fan ControllerControlSep 13, 2006
PIC Web Server SchematicMicrocontrollerSep 13, 2006
Micro based PIR to IR remote converterIROct 23, 2002
DIY Microphone Cable for iPod Touch (2nd Gen)PDASep 25, 2009
Hacking the Hot Wheels Radar Gun - includes circuit of analog front endMisc 
Laser range finder and reflectivity meter for the MARS-96 international space project (PDF)LaserOct 06, 2006
AM/FM/SW active antennaRFJan 26, 2001
Caller ID decoder (requied Postscript file viewer and/or Ordcad schematic capture)TelephoneJan 26, 2001
Clock dividerTimingJan 26, 2001
Clock doublerTimingJan 26, 2001
Headlight reminderAutomotiveJan 26, 2001
Quiz show indicatorGamesJan 26, 2001
Frequency and capacitance meterTestJan 26, 2001
CMOS oscillator using 74C14 inverting Schmitt triggerTimingJan 26, 2001
Adjustable flashing LEDLEDJan 26, 2001
Crystal 32.768KHz CMOS OscillatorTimingJan 26, 2001
Crystal oscillator using a CMOS or HCMOS inverterTimingJan 26, 2001
Video amplifierVideoJan 26, 2001
Condenser microphone hookupAudioJan 26, 2001
Phase shifterAudioJan 26, 2001
Ultrasonic transducer oscillator circuitMiscJan 26, 2001
HV supply: 12VDC in, 12KV outPowerJan 26, 2001
Generating -5VDC from +5VDCPowerJan 26, 2001
IR-related ASCII Schematics V1.00IRAug 27, 2003
Infrared remote transponderIRJan 26, 2001
Cheap 40KHz clock using one gate of a 74C14TimingJan 26, 2001
Astable 40KHz clockTimingJan 26, 2001
Build an Infrared night scopeIRJan 26, 2001
Decoding IR Remote ControlsIRJan 26, 2001
Analog Signal Acquisition for PC Printer PortPCJan 26, 2001
AC switching with TRIAC from TTLControlJan 26, 2001
'Rounding Off' a square waveTimingJan 26, 2001
More accurate PC/AT clockPCJan 26, 2001
Filtering PC bus POWERPowerJan 26, 2001
Control 120VAC relay with TTLControlJan 26, 2001
Build logic gates using discrete partsMiscJan 26, 2001
Driving a relay with a CPUControlJan 26, 2001
Telephone in use lightTelephoneJan 26, 2001
Detecting a telephone ring signalTelephoneJan 26, 2001
Phone In-Use LightTelephoneJan 26, 2001
Phone to audio interface for SSI202 inputTelephoneJan 26, 2001
Phone Off-Hook Indicator using CD4049 hex inverterTelephoneJan 26, 2001
'phone rang' indicator lightTelephoneJan 26, 2001
Phone line to audio interfaceTelephoneJan 26, 2001
Phone in-use (manually activated)TelephoneJan 26, 2001
Telephone Line MonitorTelephoneJan 26, 2001
Use old telephones as an intercomTelephoneJan 26, 2001
Phone-In-Use indicatorTelephoneJan 26, 2001
Hold function for TelephoneTelephoneJan 26, 2001
Digital/Standard Phone Line TesterTelephoneJan 26, 2001
IR detectorIRJan 26, 2001
Jacob's LadderMiscJan 26, 2001
100W RMS Amplifier circuit diagramAmplifiersJan 26, 2001
Simple microphone preamplifierPreampJan 26, 2001
PC IR Remote Control HardwareIRAug 27, 2003
Paradoxical Sound SyntheizerAudioJan 26, 2001
Switch debounce using 555TimingJan 26, 2001
RF Sniffer under 0.5MHz to above 500MHzRFJan 26, 2001
Getting power from RS-232 interfacePCJan 26, 2001
Square wave to sine wave converterTimingJan 26, 2001
Small Radio TransmitterTransmittersJan 26, 2001
12 Volt DC Fluorescent Lamp DriverLightingNov 13, 2010
Battery juicer provides a night light from almost flat batteries that would otherwise be dischardedLightingNov 13, 2010
Beam-break Detector For Camera Shutter or Flash ControlPhotoNov 13, 2010
Dual Polarity Unregulated PSU For High-End Audio AmpsPowerNov 13, 2010
High Voltage Converter: 90V From 1.5VPowerNov 13, 2010
Infra-red Light Barrier Using 555IRNov 13, 2010
Infra-Red Sensor/MonitorIRNov 13, 2010
IR On/Off Switch Using a PIC12F629 MicrocontrollerMicrocontrollerNov 13, 2010
Infrared S/PDIF ReceiverIRNov 13, 2010
RC5 Repeater to extend distance of infrared remote controlsIRNov 13, 2010
Super Simple 3 Watt Audio Power Amplifier based on TDA1015AmplifiersNov 13, 2010
Transistor TesterTestNov 13, 2010
VGA to BNC Adapter (Converter)VideoNov 13, 2010
White LED LampLEDNov 13, 2010
Wire Tracer (Receiver)TestNov 13, 2010
Wire Tracer (Transmitter)TestNov 13, 2010
PIC ICDMicrocontrollerOct 23, 2002
Dreamcast interfaceGamesAug 09, 2002
Ultrasonic Range Finder & ImagerData AcquisitionJun 09, 2002
iPod / USB MP3 charger using MC34063 switchmode regulatorPDA 
Elecraft XG2 receiver test oscillator (PDF)TestSep 13, 2006
Infrared beam barrier / proximity detectorIR 
Simple electronic buzzerAudio 
Big Ben sound effects generatorAudio 
Charge Monitor for 12V lead acid batteryPower 
Wiper Speed ControlAutomotive 
PC based Frequency MeterPC 
7 segment rolling display using PCPC 
JAM(Just A Minute) Quiz Game CircuitGames 
Running Message DisplayLED 
Simple car battery chargerAutomotiveJun 18, 2003
Clap activated remote controlControl 
Contactless Mains Voltage IndicatorTest 
Automatic Staircase Light 1Lighting 
Automatic Staircase Light 2Lighting 
Clack Clack Electronic BellAudio 
Electronic Astrologer (decision maker)Games 
Electronic diceGames 
Light Operated SwitchControl 
Mini emergency lightLighting 
Mini tester: Handles continuity testing, resistor testing, capacitor testing and diode testingTest 
Musical Electronic BellAudio 
MW Transmitter can be used as an inter-room radio telephoneTransmitters 
NiCd Cell ChargerPower 
Pocket Transmitter that can cover 20 to 25 meters with a telescopic antennaTransmitters 
Reflex Action GameGames 
Simple Traffic Light ControllerModels 
Voice AmplifierAmplifiers 
Discrete LED Color OrganLED 
Automatic Plant Irrigation System Circuit for Watering Plants without any Human Interference.MiscDec 07, 2014
BCD to 7 Segment LED Display Decoder CircuitLEDApr 26, 2014
25W MOSFET audio amplifierAmplifiersFeb 21, 2005
50W audio amplifier using ICL8063AmplifiersFeb 21, 2005
Digital volume controlAudioFeb 21, 2005
Electronic attenuatorAudioFeb 21, 2005
Speech recorded using ISD2560AudioFeb 21, 2005
Precision audio millivoltmeterTestFeb 21, 2005
Amplified ear for surveillanceAmplifiersFeb 21, 2005
Flashing / pulsing third brake like for carsAutomotiveFeb 21, 2005
Headlight flasherAutomotiveFeb 21, 2005
Speed alert - wireless portable unitAutomotiveFeb 21, 2005
Parking aid senses distance to rear of vehicleAutomotiveFeb 21, 2005
Automatic headlight brightness switchAutomotiveFeb 21, 2005
Flashing heartGamesFeb 21, 2005
Electronic millipede robotModelsFeb 21, 2005
Circuit diagram of 3V LED chaser using 4017LEDFeb 21, 2005
6V ultra-bright LED chaser using 74HC4017LEDFeb 21, 2005
Smart card programmerMicrocontrollerFeb 21, 2005
Decoder for encoded transmissions in Videocrypt and D2MACVideoFeb 21, 2005
Circuit for gold wafer cardMiscFeb 21, 2005
Jupiter card programemrMicrocontrollerFeb 21, 2005
PIC16F84 based diode testerTestFeb 21, 2005
Nokia 3310 Lcd Thermometer using DS18B20MiscFeb 21, 2005
Lost keys finder using HCF4069MiscFeb 21, 2005
SmartCard PC EmulatorPCFeb 21, 2005
Economy radar detectorAutomotiveFeb 21, 2005
S-Video to RCA adapterVideoFeb 21, 2005
Digital pedometer circuit diagramMedicalFeb 21, 2005
Cellular Phone calling detector (detects RF field)TelephoneFeb 21, 2005
Cuckoo sound generatorAudioFeb 21, 2005
RS-232 Laser TransceiverLaserMay 01, 2004
RS-232 laser transceiverLaserFeb 21, 2005
Casio dataloggerPDAFeb 21, 2005
Relay interface add-on board for PCPCFeb 21, 2005
8-way relay interface board for PC parallel printer portPCFeb 21, 2005
Stepper motor controller for PC parallel portPCFeb 21, 2005
3-axis stepper motor controller for PC parallel portPCFeb 21, 2005
Optically isolated stepper motor controllerControlFeb 21, 2005
PC based thermometer based on Dallas DS1621PCFeb 21, 2005
VGA to SCART adapterVideoFeb 21, 2005
Basic UPS Power SupplyPowerFeb 21, 2005
Fuse monitor / alarmPowerFeb 21, 2005
4 watt FM transmitter circuit diagramTransmittersFeb 21, 2005
FM transmitter bugTransmittersFeb 21, 2005
Television signal amplifierVideoFeb 21, 2005
Small radio transmitterTransmittersFeb 21, 2005
Electronic Eavesdropping Devices Detector (bug detector)RFFeb 21, 2005
20dB VHF AmplifierRFFeb 21, 2005
30 watt FM linear amplifier circuit diagramRFFeb 21, 2005
AM transmitterTransmittersFeb 21, 2005
2 Transistor FM Voice TransmitterTransmittersFeb 21, 2005
Linear FM 50 watt amplifier with BLY90RFFeb 21, 2005
15 watt FM transmitter circuit schematicTransmittersFeb 21, 2005
Video signal amplifier circuitVideoFeb 21, 2005
CB (27MHz citizens band) receiverRFFeb 21, 2005
Circuit for three axis robot arm based on stepper motors out of 5 1/4" drivesModelsNov 10, 2009
Lightning DetectorMiscFeb 21, 2005
Geomagnetic field detectorMiscFeb 21, 2005
Frost alarmAlarmsFeb 21, 2005
Ultrasonic radar alarmAlarmsFeb 21, 2005
iRDA transceiver to extend IR port range up to 15 metersIRFeb 21, 2005
Remote digital thermometer sends data over AC power lineData AcquisitionFeb 21, 2005
Phone line in use indicatorTelephoneFeb 21, 2005
Telephone music on hold interfaceTelephoneFeb 21, 2005
Soft musical telephone ringerTelephoneFeb 21, 2005
Telephone amplifierTelephoneFeb 21, 2005
Telephone line monitorTelephoneFeb 21, 2005
Cut telephone line detectorTelephoneFeb 21, 2005
FM telephone line bug transmitter (88MHz to 94MHz)TelephoneFeb 21, 2005
Continuity tester using transistorsTestFeb 21, 2005
Latching continuity tester using 4093TestFeb 21, 2005
IR remote control testerIRFeb 21, 2005
Linear Resistance MeterTestFeb 21, 2005
Crystal tester circuit diagramTestFeb 21, 2005
Capacitance meterTestFeb 21, 2005
Digital voltmeter (DVM)TestFeb 21, 2005
Transistor tester using 555 timer and 4027TestFeb 21, 2005
Function generator based upon 8038 waveform generator ICTestFeb 21, 2005
Triangle / Square wave generatorTimingFeb 21, 2005
Picoammeter circuit schematic with 4 ranges using CA3420TestFeb 21, 2005
Beeper to find short circuits (continuity tester)TestFeb 21, 2005
Voltage follower with 1G ohm input resistanceData AcquisitionFeb 21, 2005
Led display digital VoltmeterLEDFeb 21, 2005
MOSFET tester for N-type MOSFET transistorsTestFeb 21, 2005
Inductive meter adapter to measure inductance using a frequency counterTestFeb 21, 2005
Crystal tester that covers a range of 32kHz to 24MHzTestFeb 21, 2005
Oscilloscope testing module (Huntron circuit) that shows Lissajous patternsTestFeb 21, 2005
Voltage monitor with LED indicatorPowerFeb 21, 2005
Logic probe with 7-segment display based on 74LS00 and 74LS47TestFeb 21, 2005
Wireless transmitter for PIR using Holtek HT12ETransmitters 
OPT301 Laser receiverLaser 
Heartbeat transducer using infrared LED / detectorMedical 
ECG amplifier with right leg driveMedical 
High current regulated power supplyPowerOct 31, 2002
Low-voltage light dimmerLightingNov 17, 2002
Active bandpass filtersFilterNov 01, 2002
Bandpass filtersFilterNov 01, 2002
AM BCB radio receiverRFOct 23, 2002
Regenerative shortwave receiverRFJun 08, 2002
Miniature audio amplifierAmplifiers 
Optical Heart Rate MonitorMedicalSep 10, 2006
PIC Project #1 - RS232 to I2C InterfaceMicrocontrollerJan 26, 2001
RF front-end for triple conversion GPS receiver (PDF)RFMar 01, 2003
Design and build your own iPod docking stationPDAMay 30, 2007
Various tube crossover circuitsAudioJan 31, 2003
Serial Port A/D-converterData AcquisitionJan 26, 2001
Audio amplifier output relay delayAmplifiersJan 26, 2001
TV/Radio antenna cable galvanic isolatorVideoJan 26, 2001
Audio line isolatorAudioJan 26, 2001
Connect two CD-ROM drives to one soundcardPCJan 26, 2001
Centronics port D/A converters and low-pass filterData AcquisitionJan 26, 2001
4-channel dimmer rack circuit diagramLightingNov 17, 2002
Dynamic microphone to electret microphone inputAudioJan 26, 2001
Fogger smoke machine controllerMiscJan 26, 2001
Headphone driving circuit for soundcardsPCJan 26, 2001
Simple line mixerMusicJan 26, 2001
Simple IR transmitter circuitIRJan 26, 2001
Simple infra-red detectorIRJan 26, 2001
Experimental laser data linkLaserJan 26, 2001
Simple light sensor adapter for oscilloscopeTestJan 26, 2001
Line level signal to microphone input adapterAudioJan 26, 2001
Simple two line output combinerAudioJan 26, 2001
Adjustable power supply using LM317PowerJan 26, 2001
Get power out of PC parallel portPCJan 26, 2001
Simple microphone preamplifierPreampJan 26, 2001
Electret microphone powering circuitsAudioJan 26, 2001
Simple MIDI testerMusicJan 26, 2001
Null Printer AdapterPCJan 26, 2001
PC speaker volume control circuitPCJan 26, 2001
Use amplifier phono input as line level inputAudioJan 26, 2001
How to get power from PC to your circuitsPCJan 26, 2001
Simple +5V power supply circuitPowerJan 26, 2001
RS-232 surge protectionPCJan 26, 2001
Simple RS-232 serial port buffer circuitPCJan 26, 2001
Get power out of PC RS-232 portPCJan 26, 2001
Sound Blaster Microphone PreamplifierPCJan 26, 2001
Sega 3D glasses interface circuit diagramsPCJan 26, 2001
0-10V control for RC servosModelsJan 26, 2001
Speaker signals to line level inputsAudioJan 26, 2001
S-video to composite video adapterVideoJan 26, 2001
TDR cable reflection tester (Time Domain Reflectometer)TestSep 21, 2006
Telephone privacy adapterTelephoneJan 26, 2001
Telephone ringing circuitsTelephoneJan 26, 2001
Simple circuit to connect telephone equipment to audio mixerTelephoneJan 26, 2001
VGA to RGB + composite sync -converterVideo 
VGA to TV converterVideoJan 26, 2001
VGA to PAL and NTSC converterVideoJan 26, 2001
A-weighting filter from an old Ampex service manualFilterMay 07, 2010
Convert Atari-style joystick to PC joystick portPCJan 26, 2001
Fake Joystick circuitPCJan 26, 2001
Using the joystick port as general purpose inputPCJan 26, 2001
Connect other circuits to PC joystick portPCJan 26, 2001
HeNe laser power supplyLaserJun 09, 2002
Video/Audio Wireless TransmitterVideoOct 23, 2002
Using an ADXL330 accelerometer with an AVR microcontrollerMicrocontrollerJan 09, 2010
Peggy - A Light Emitting Pegboard DisplayLED 
LPG leakage alarm using SEN-1327 gas sensor module (detects 4 other dangerous gases)AlarmsJul 17, 2012
Build your own iRDA SIR Transceiver (Dongle) using MCP2120PCAug 27, 2003
Programmable Optical Slave Flash Trigger for Digital Cameras using PIC12F675Photo 
7MHz SSB TransceiverRFMay 01, 2004
Homebuilt MP3 PlayerMusic 
5 Zone Alarm Circuit circuit diagramAlarms 
Strain gauge sensor interfaceData Acquisition 
Ultrasonic Distance Measurer based on Freescale MC9RS08KA2 (PDF)Microcontroller 
Model 2030 XRAY monitor instruction manual including schematics (PDF)MedicalSep 13, 2006
Rangefinder with Fast Multiple Range CapabilityLaserOct 06, 2006
Laser diode transmitter RF sectionLaser 
DC Fault Protection Circuit for Audio AmplifiersAudioJan 29, 2010
Soft Power On Tester for AmplifiersTestJan 29, 2010
Zonk Machine and Treble BoosterMusicJan 31, 2003
One 9V battery gives +18, +25, +33VPowerJul 24, 2002
+9V *and* -9V from one batteryPowerJul 24, 2002
Pulse Induction Metal Detector part 1 (PDF)MiscJun 27, 2010
Pulse Induction Metal Detector part 2 (PDF)MiscJun 27, 2010
Lightning shutter trigger for a camera using an ArduinoPhotoNov 13, 2010
Camera Axe open hardware and open software project for camera triggeringPhotoNov 13, 2010
Direction sensing infrared motion detector using PIR (PDF)IR 
Universal telephone holdTelephoneJan 26, 2001
Video switcher - run up to four cameras into one video monitor (PDF)Video 
Talking phone dial monitor (PDF)TelephoneJan 26, 2001
Stepper motor positionerControlJan 26, 2001
Infrared Motion Detector using a PIR sensor (PDF)IR 
Pyroelectric Infrared (PIR) SensorIRJan 26, 2001
Mobile APRS / GPS tracking systemMiscMay 01, 2004
GPS receiver support kitMiscMay 01, 2004
GPS receiver (Gamin, Eagle etc) to PC interface cablesPCMar 23, 2003
Heart of LEDsLEDOct 23, 2002
Christmas StarLEDOct 23, 2002
Christmas treeLEDOct 23, 2002
Simple Skype VoIP analog adapterTelephoneSep 10, 2006
Brain-Wave MachineMedicalNov 27, 2002
Cranial Electrotherapy Stimulation (CES) circuit diagramMedical 
Lie detectorMedicalOct 30, 2002
Simple lie detectorMedicalOct 30, 2002
Furby reverse-engineered circuitGamesApr 27, 2003
Circuit and Arduino sketch for interfacing to a DS18B20 1-wire temperature sensorMicrocontrollerJul 21, 2013
Simple MPPT (maximum power point tracker) for photovoltaic arrays (PDF)SolarMar 09, 2012
TXTVb - 70cm ATV Test Generator (PDF)Test 
BCD readout frequency counterTestAug 18, 2009
Binary clock circuit diagramTimingAug 18, 2009
Experimental DDS frequency synthesizer uses the AD9851TimingOct 08, 2009
Dekatron circuit diagram - device used for dividing by 10 during the valve eraMiscOct 25, 2009
Circuit diagrams for making logic gates from discrete componentsMiscOct 25, 2009
Simple intercom circuit diagramTelephoneOct 25, 2009
LCD Frequency CounterTestAug 18, 2009
Circuit for remote lighting controller using a 433MHz AM keyfob transmitterLightingOct 25, 2009
LED matrix clock circuit diagramTimingAug 18, 2009
Miniscope - simple all-valve 1-inch CRT oscilloscopeTestOct 25, 2009
Positive Feedback Circuit for Isometric Muscle ExperimentsMedicalNov 05, 2009
Z80 Computer circuit diagramPCAug 18, 2009
Giant nixie clock circuit diagramTimingAug 18, 2009
Panel-mounting clock circuit diagramTimingAug 18, 2009
Basic 78xx series regulator mains power supply circuit diagramPowerOct 25, 2009
Simple QRSS callsign keyer based on an Atmega AVR programmed in CMicrocontrollerNov 05, 2009
Panel Mounting Radio Frequency CounterTestAug 18, 2009
Giant T-shaped LED matrix display board for financial applications containing 275 8x8 LED modulesLEDOct 25, 2009
Simple Frequency CounterTestAug 18, 2009
Sidereal clock project with circuit diagramsTimingAug 18, 2009
Heathkit signal generator user manual and circuit diagramTestOct 25, 2009
Spectrum analyzer Mk 1TestAug 18, 2009
Spectrum analyzer Mk 2TestAug 18, 2009
TinyScope - simple all-valve 1-inch CRT oscilloscopeTestOct 25, 2009
Asynchronous 40-bit TTL CPUMicrocontrollerAug 18, 2009
USB charger circuit diagramPowerAug 18, 2009
Z80 controlled Viscometer projectTestAug 18, 2009
Wind speed loggerData AcquisitionOct 25, 2009
Wind speed logger Mk2Data AcquisitionOct 25, 2009
The Great Z80 Computer ProjectPCAug 18, 2009
AVR-Based Serial Port IR ReceiverMicrocontrollerOct 23, 2002
Ethernet interface for Commodore 64 computerPC 
i2c-tiny-usb, a simple i2c interface for the usb portPC 
LCD2USB, cheap open source text LCD interfacePC 
LEDMATRIX, a 80x32 pixel DIY LED matrix displayLED 
Interfacing ADXL202 accelerometer to PalmPilotPDAApr 27, 2003
SPI2CF, a fast and efficient WLAN interface for the AVRMicrocontroller 
TiltStick, a motion sensing device (USB interface to accelerometer)PC 
Building an Infrared Transmitter for Your PCPC 
Minimum Theremin Kit SchematicAudioSep 13, 2006
FM radio for a PIC (uses TDA7000 IC which is now obsolete)PCSep 08, 2009
Lightning detector circuit diagramMiscSep 08, 2009
Build an iButton electronic lock based around a AT91C2051 microcontroller (includes ASM source code)AlarmsNov 10, 2009
AM receiver circuit diagramRFSep 08, 2009
Using an Apple II+ Computer as a Flash Intervalometer (PDF)PhotoMay 09, 2010
Heathkit Groundtrack GR-1290 VLF metal detector circuit diagram and detector coil construction notesMiscJun 27, 2010
White's Surfmaster PI (pulse induction) metal detector schematic diagramMiscJun 27, 2010
Ultrasonic Radar Alarm Circuit DiagramAlarms 
10 tricks for interfacing to the PIC16C508MicrocontrollerNov 05, 2009
Circuit to connect a rotary encoder to a Arduino UNOMicrocontrollerJul 21, 2013
555 Based Simple Servo ControllerControl 
Fluorescent Tube "Strip light" DriverLighting 
Field Strength Meter (FSM) covers 2Mhz - 1Ghz with peak reception at 3-200MhzTest 
Simple Function Generator using TL084 or other opampTiming 
H Bridge controller for DC motorsControl 
Advanced High Voltage PSU circuitPower 
Authentic Looking Knight Rider Led ProjectAutomotive 
6 Pole ElectroMagnet Motor (aka Simple Brushless motor)Misc 
88-108Mhz FM Radio Transmitter with 3 transistor stagesTransmitters 
Serial servo controller for interfacing hobby servos via RS232 to a PCPC 
Solid State Tesla Coil and Wireless PowerMisc 
Tesla coil construction projectMisc 
12 Vdc - 120 Vac Inverter SchematicPowerJan 01, 2003
POV Persistence Of Vision 2 x 32 LED displayLED 
Vareity of circuits for interfacing to/from TTL logicMisc 
Victoria TAFE programmer (based on AT89C2051)MicrocontrollerJan 31, 2003
JDM programmer circuit diagramMicrocontrollerJan 31, 2003
PIC micro programmer circuit diagramMicrocontrollerJan 31, 2003
Dinsmore 1490 digital compassMiscNov 29, 2002
Geiger counter circuit diagramMiscNov 29, 2002
Speech recognition using HM2007MicrocontrollerNov 29, 2002
PIC microcontroller servo motor interfaceMicrocontrollerNov 29, 2002
PIC micro multiple servo motor interfaceMicrocontrollerNov 29, 2002
Electric field disturbance monitorMiscJan 26, 2001
3 KHz low pass filter plus audio amplifier circuit diagramFilterApr 14, 2010
Micropower pulse generator (PDF)TimingJan 26, 2001
Inexpensive seismometer projectMiscDec 15, 2002
Constant current LED driver circuit using an NPN transistor to control an N-channel MOSFETLEDJul 11, 2012
Simple 430MHz band FM transmitter uses only 2 FETtransistorsTransmitters 
110mW emitter follower audio power amplifierAmplifiersJan 22, 2010
AM transmitter using no power supplyTransmitters 
NE555 drives a speakes: Pulse Width Modulation AmplifierAudioMar 30, 2010
UHF signal generatorTest 
VHF signal generatorTest 
Judge Dredd pinball locking ring modificationGames 
PIC micro frame grabber (TDA8708)VideoFeb 01, 2003
Serial interface adapter for iPod LinuxPDA 
Digitally Addressable DALI Dimming Ballast (PDF)LightingDec 27, 2004
New and Improved Sound Card Packet Interface tested with PSK31 and APRSPCOct 27, 2009
Home security projectAlarmsNov 17, 2002
PC Controlled RC car construction projectModels 
DC Motor Controller using 74 series chipsControl 
PIC-Programmer 2 circuit diagram with links to programming softwareMicrocontrollerJun 09, 2002
PIC-Programmer 2 for PIC16C84 etc circuit diagram with links to programming toolsMicrocontroller 
Pulse Circuits for Infrared LEDs and Visible Diode LasersLaserAug 04, 2012
Pulse Circuits for Infrared LEDs and Visible Diode LasersLaserMar 04, 2010
LED Modulation Circuits including 5MHz and 50MHz versionsLEDApr 17, 2011
Measuring the speed of light with an infrared LED / photodiode (TDOA)IRJun 13, 2011
Canon DSLR cable shutter release usin 4N25 for optical isolationPhotoSep 25, 2009
Spatial Distortion Reduction Headphone AmpAmplifiersJan 31, 2003
Simple GPS Stabilised 10 MHz OscillatorTiming 
Sanyo 20EZ monitor circuit diagramPCMar 18, 2003
Burger Time Arcade Game circuit diagram (PDF)GamesMar 17, 2009
Dig Dug Arcade Game (800k ZIP)GamesMar 18, 2003
Frogger Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Frogger Sound/ROM - FROGSND Arcade game circuit diagram (PDF)GamesMar 30, 2014
Gyrus Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Junior Pacman Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Ladybug Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Mappy Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Moon Cresta Arcade circuit diagram (PDF)GamesMar 18, 2003
Mr.Do Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Pengo Arcade Game circuit diagram (PDF)GamesMar 18, 2003
PacLand Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Q*Bert Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Qix Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Scramble Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Time Pilot'84 Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Xevious Arcade Game circuit diagram (PDF)GamesMar 18, 2003
Robotic microcontroller boardModelsJan 31, 2003
Single to 3-phase power conversionPower 
Low noise PIN diode laser receiver circuitLaser 
Circuits for biasing and modulating laser diodesLaser 
inexpensive high speed microwave data link using an Alpha Gunnplexer for 10 Mbps data rateRF 
18 dB LT1253 DDS amplifier circuit diagramRF 
23 dB Bipolar DDS AmplifierRF 
15M CW Transceiver designRF 
20 Meter CW TransceiverRF 
30 Meter, Discrete Component CW Transceiver Built Manhattan-styleRF 
K8IQY's Original 2N2/40 CW Transceiver RigRF 
40 to 6 Meter "No Tune" TransverterRF 
SW30+ 30 Meter CW TransceiverRF 
-20 dB Couplers for use with a with a spectrum analyzer or other sensitive detectorTest 
-20 dBm, 14.060 MHz Precision Signal SourceTest 
RC Audio OscillatorAudio 
Precision VXO for Crystal Characterization & MatchingTest 
Return Loss BridgeTest 
Lossless portable digital audio player using the Microchip PIC32Music 
Water system controller (PDF)Control 
GPS LCD Display ProjectMicrocontrollerJul 24, 2002
PIC16F84 LED chaserMicrocontrollerNov 17, 2002
PIC micro LED projectsMicrocontrollerJun 18, 2003
PS/2 keyboard keystroke logger based on Atmel 89C2051MicrocontrollerJun 20, 2004
Aurora Alarm: Automated Detection System for the Northern LightsMisc 
6502 Microprocessor KitMicrocontrollerMay 19, 2015
68k Single Board ComputerMicrocontrollerMay 19, 2015
AT89C4051based digital clock with 16x2 LCDMicrocontrollerMay 19, 2015
Digital Clock with Alarm Using DS1307MicrocontrollerMay 19, 2015
Realtime Clock with LCD based on an Atmel AT89C4051MicrocontrollerApr 22, 2014
Simple RS232C Level Converter using TransistorsPCJun 19, 2011
AVR910 - AVR ProgrammerMicrocontrollerJun 07, 2011
AVR thermometer using AT90S2313 and DS1820MicrocontrollerMay 19, 2015
HC-11 Evaluation BoardMicrocontrollerMay 19, 2015
SBC built with 16-bit Intel Embedded Microprocessor, 80C186EBMicrocontrollerMay 19, 2015
16-bit microprocessor learning board based on Intel 80C188EB Embedded MicroprocessorMicrocontrollerMay 19, 2015
C-52 Evaluation Board based on a 89C52MicrocontrollerMay 19, 2015
C-52 Evaluation Board V2.0 based on a 89C52MicrocontrollerMay 19, 2015
C-52 Evaluation Board Robot ControllerMicrocontrollerMay 19, 2015
Cheap Loader Cable of Asim's ISP for 89S51 89S52MicrocontrollerMay 19, 2015
Data Acquisition& Logging System UsingAT89c51Data AcquisitionMay 19, 2015
DC Voltage and Current SourcePowerMay 19, 2015
Student DC power supplyPowerJun 19, 2011
Electronic distance meter based on Motorola 68HC908QY4MicrocontrollerJun 20, 2004
MCS-51 Propeller LEDLEDMay 19, 2015
Easy-Downloader V1.1 for ATMEL 89C2051/4051MicrocontrollerMay 19, 2015
Easy-Downloader V1.1 with SDCCMicrocontrollerMay 19, 2015
Atmel AVR ATMega 8535/16/32 and AT89S5x family learning kitMicrocontrollerJun 07, 2011
Make your own PIC ProgrammerMicrocontrollerMay 19, 2015
F84 low-cost and very simple serial programmer for a PIC16F84 Microchip Flash MicrocontrollerMicrocontrollerMay 19, 2015
F84 simple real-time controller with PIC16F84 running at low powerMicrocontrollerMay 19, 2015
Fan timer based on Motorola 68HC908QT2MicrocontrollerJun 20, 2004
Isolated RS232C for PIC16F84 or other microcontrollersMicrocontrollerJun 19, 2011
ISP Flash Microcontroller Programmer for Atmel DevicesMicrocontrollerMay 19, 2015
Atmel AVR and 8051 series ISP programmerMicrocontrollerJun 20, 2004
Interfacing Alphanumeric LCD to Parallel Port using Visual Basic 6.0PCMay 19, 2015
Easy debugging serial terminal with LCD displayMicrocontrollerMay 19, 2015
SPI Interface Big 7-Seg LEDLEDJun 19, 2011
AT89C2051 line-follower robotMicrocontrollerJan 26, 2001
Interface LTC1298 with Standard Parallel PortPCMay 19, 2015
RS232C level converters based on Maxim MAX232 or Dallas DS275PCMay 19, 2015
M-Logger V1.0 based on PIC18F46J11 microcontroller and a DS1820 temperature sensorMicrocontrollerMay 19, 2015
MTK-85 8085 Microprocessor Training KitMicrocontrollerJun 07, 2011
Isolated RS422 adapter for PC serial portPCJun 19, 2011
Simple and easy build RS232C-RS485 converterPCJun 19, 2011
Circuit that provides a short circuit protected power supply from PC 12V supply voltage.PowerMay 19, 2015
Digital pH MeterTestMay 19, 2015
In-Circuit PIC Loader (parallel port based)MicrocontrollerMay 19, 2015
PIC18F2550 Project BoardMicrocontrollerMay 19, 2015
PIC Harmonic Distortion Meter for measuring the quality of AC supplyTestMay 19, 2015
Data Acquisition System using ATmega8Data AcquisitionJun 07, 2011
Atmel 89C2051prototyping boardMicrocontrollerApr 22, 2014
4-Channel Pt100 ThermometerData AcquisitionMay 19, 2015
Pyranometer to Current ConverterData AcquisitionJun 19, 2011
PC Power Reboot Circuit for ATX power suppliesPCJun 19, 2011
AVR Line Following RobotModelsMay 19, 2015
Isolated Full Duplex RS232C Interface for a PCPCJun 19, 2011
RS232 Expander - Expands PC's COM port from COM1 to COM1/1 and COM1/2. No active partsPCMay 19, 2015
Miniature Real-time Controller based on a 89C2051ControlApr 22, 2014
S-52 Simple Learning Board using Atmel AT89S52MicrocontrollerMay 19, 2015
Night light saver (PIC12C508)MicrocontrollerJun 09, 2002
Night Light Saver V5.0 using a AT89C2051 and TRIACLightingApr 22, 2014
Night Light Saver V6LightingApr 22, 2014
Cheap oscilloscope and sensor probes for physics experiment in schoolTestMay 19, 2015
Circuit for soft start module for induction motorControlJun 19, 2011
Solar Energy MeterSolarMay 19, 2015
Solar Recorder for measuring daily insolationSolarMay 19, 2015
Solar station for insolation measurement with Ubuntu server 7.10 and a 24-bit Delta-sigma converterSolarJun 07, 2011
SPI Flash Microcontroller Programmer for 8051 and AVR series devicesMicrocontrollerMay 19, 2015
Java Bot - Simple line follower robotModelsJun 19, 2011
Atmel 89S and AVR Programmer (STK200)MicrocontrollerJun 07, 2011
Thermistor Thermometer using 12-bit ADC, 89S52 and LED displayMicrocontrollerMay 19, 2015
Thermistor Thermometer: LCD versionMicrocontrollerMay 19, 2015
DigiThermo - a laboratory instrument that measures time and temperatureTestApr 22, 2014
Time switch with two optotriacs to control resistive AC loads directlyControlMay 19, 2015
Tiny 2313 Project Development BoardMicrocontrollerJun 07, 2011
USB and GLCD expansion board for 8051 SBCMicrocontrollerJun 20, 2004
USB Easy-Downloader V5.0 for 89S52 and SST89E516RD chips with USB port connectionMicrocontrollerMay 19, 2015
+/-5A Voltage Controlled Current SourcePowerMay 19, 2015
AT89C2051 Programmer using Linux terminalMicrocontrollerApr 22, 2014
xTimer V1.0 a 4-Channel Timer based on a 89C4051 + MAX7219 display driverTimingApr 22, 2014
xTimer using CMOS shift register 4094 for driving 7-segment LED directlyTimingApr 22, 2014
Z80 Microprocessor KitMicrocontrollerMay 19, 2015
FAN Thermostat controlled by IR remote controllerIRMay 19, 2015
Breadboard supply - very low dropout adjustable power supplyPowerOct 12, 2009
Bedazzler: Do-it-yourself Handheld LED-Incapacitator (non-lethal weapon)LEDOct 12, 2009
Dimmable Li-Ion Halogen Bike LightLightingOct 12, 2009
Solderless Breadboard Arduino Clone for Arduino prototypingMicrocontrollerOct 12, 2009
Digg Button KitMiscOct 12, 2009
Drawdio - A very simple musical synthesizer that uses the conductive properties of pencil graphiteMusicOct 12, 2009
Ethernet shield for Arduino (Xport)MicrocontrollerOct 12, 2009
Fuzebox - open source 8-bit game console based on Atmel ATmega644-20PUGamesOct 12, 2009
GPS / Datalogging shield for Arduino microcontrollerMicrocontrollerOct 12, 2009
Ice Tube Clock - Vacuum fluorescent display (VFD) clockTimingOct 12, 2009
Real-world MIDI interface platform project including circuit diagram and PCB design filesMusicOct 12, 2009
Persistance of vision (POV) toyGamesOct 12, 2009
Portable MP3 music playerMusicOct 12, 2009
Small battery-powered USB charger including circuit diagram and PCB layoutPowerOct 12, 2009
Arduino based controller interface for servo motors, stepper motors and DC motorsMicrocontrollerOct 12, 2009
Arduino microcontroller prototyping systemMicrocontrollerOct 12, 2009
SIM card reader circuit diagramMiscOct 12, 2009
Persistence of Vision Display for BikesLEDOct 12, 2009
High power infrared remote control to turn off television sets from a distanceIROct 12, 2009
USBtinyISP - AVR programmer & SPI interface projectMicrocontrollerOct 12, 2009
Wave Bubble self-tuning portable RF jammerRF 
Wave Bubble - A design for a self-tuning portable RF jammerRFOct 12, 2009
Wave (Audio) shield for Arduino microcontrollerMicrocontrollerOct 12, 2009
Bassline synthesizer/sequencerMusicOct 12, 2009
YBox2 - DIY networked set-top box that connects to a TV to deliver Internet contentVideoOct 12, 2009
Mini-Beacon - miniature programmable LED Flasher that is based around a PIC12F629 microcontrollerLED 
Subwoofer Filter, Gainer, Auto Power SystemAudio 
PC-based ISA data acquisition and control boardPCSep 13, 2006
Circuit for driving a liquid crystal (LCD) shutter to simply pass or block lightMiscDec 21, 2009
Linux Infra-red Remote Control (LIRC)PCApr 12, 2001
Simple home made ADS-B receiver that takes IF from a modified receiverRFOct 04, 2010
Very Simple ADSB Receiver using a TV tunder to allow reception of aircraft transpondersRFOct 04, 2010
115200 RS232 QPSK RF modem projectRFOct 04, 2010
Build your own MARES dive computer IRIS interface for RS232PCOct 04, 2010
3.3V / 5V Regulated Power Supply CircuitPowerJul 03, 2011
Acceleration Sensing - gesture controllers for robotic musical instrumentsModelsJan 09, 2010
Distance Sensing - devices for wireless distance and position determinationModelsJan 09, 2010
Doppler radar based gesture measurement system capable of delivering positional informationModelsJan 09, 2010
Infrared Body SensingIRJan 09, 2010
Homebuilt RS232 LCD InterfacePCJun 18, 2003
Lie detectorMisc 
Project to capture infrared remote control signals and play them back, based on Atmel ATMEGA48 microIRJan 17, 2010
MIDI Controller FootpedalMusicAug 14, 2002
DIY Serial MIDI Interface (80C51/80C31 Version)MusicAug 14, 2002
Homemade Serial to Nokia MBus Interface on a PCB, without using Zener diodesPC 
Microcontroller sensor and actuator interfacesMicrocontrollerApr 27, 2003
Hi-Fi Preamp with remote-control and other advanced featuresPreamp 
Actvie speaker based on a dual op-amp (LM833) and TDA2030 power ampAudio 
4 channel power amplifier with bi-amping and bridging optionsAmplifiers 
Amplifier based on LM4780 including a thermal shutdown featureAmplifiers 
Lead-Acid Battery MonitorPower 
FailureBot 5 - A Line Following RobotModelsNov 16, 2010
Complete Design for Giant 8-foot LCD Counter (Zip file)MicrocontrollerMar 27, 2009
PIC12C509 logic gate replacement for nitrogen filler (ZIP file)MicrocontrollerMar 01, 2003
PIC demo boardMicrocontrollerOct 31, 2002
Disco light controller (ZIP file)LightingMar 01, 2003
DS1821 programmable thermostatControlMar 01, 2003
PIC12C509 Gym Timer (ZIP file)MicrocontrollerMar 01, 2003
PIC LCD and Keypad driverMicrocontrollerOct 31, 2002
PIC12C508 Phase Controller for 2kW heater (ZIP file)MicrocontrollerMar 01, 2003
PIC16F84 TRIAC / IGBT brightness phase controllerMicrocontrollerMar 01, 2003
PIC16F84 pulse monitor with date/time output (ZIP)MicrocontrollerMar 01, 2003
Simple metal detector based on a PIC12F683 microcontrollerMiscJun 27, 2010
Three component bat detector based on a PIC12F683 microcontrollerMiscJun 27, 2010
Mini oscilloscope based on PIC18F4620 and standard 16x2 text LCD display moduleTestJun 27, 2010
PIC based touch clock that demonstrates interfacing a PIC microcontroller to an LCD touch panelMicrocontrollerJun 27, 2010
Pico OSD, a PIC video superimposerVideoJun 27, 2010
A PIC16F84A Alarm ClockMicrocontrollerJun 27, 2010
PIC16F877A Thermometer with MCP9700A sensorData AcquisitionJun 27, 2010
A Voice Controlled LED Light Show using a VRStampMicrocontrollerJun 27, 2010
PIC PAL Video Library including source code and circuit schematicsVideoJun 27, 2010
Cheap Ultrasonic Range Finder based on a PIC microcontrollerMicrocontrollerJun 27, 2010
Cheap Ultrasonic Range Finder based on PIC16F877A with a 8MHz crystalMicrocontroller 
A PIC16F819 Dymoclock (also demonstrates interfacing 30 LEDs to a PIC using only six I/O pins)MicrocontrollerJun 27, 2010
MemoSound game based on a PIC16F84AGamesJun 27, 2010
EasyPic2 with on-board Ethernet AdapterMicrocontrollerJun 27, 2010
Automatic LED display dimmer using a LED as a light sensorLEDJun 27, 2010
DCF-77 PIC LED clock (DCF77 is the name of a German radio station on 77.5 KHz)TimingJun 27, 2010
DCF77 PIC16F84A Single-Nixie clock (DCF77 is the name of a German radio station on 77.5 KHz)TimingJun 27, 2010
Yaesu FT-736R doppler compensationRFAug 14, 2002
AI-1 ("All-in-one") Remote - photographic accessory that you can buildPhoto 
HeadBanger Headphone AmpAmplifiersJan 26, 2001
Pad launch controller for model rocketsModelsJun 17, 2003
Stage center reverb unit circuit schematicMusicApr 14, 2010
Custom USB tyre pressure monitoring systemAutomotive 
Simple flashing light circuitModelsJan 26, 2001
Simple flashing light circuitModelsJan 26, 2001
A dual alternating flashing light circuitModelsJan 26, 2001
Simple flashing light circuitModelsJan 26, 2001
A dual tandem flashing light circuit powered by a 9 volt batteryModelsJan 26, 2001
Simulate the Gyralite (dual flashing headlights).ModelsJan 26, 2001
Moderately complex train detector using an infrared LED and an infrared detectorModels 
Simple train detector using ambient light and a photocellModelsJan 26, 2001
Aladin interfacePDAJun 13, 2002
Acceleration monitor using ADXL202 and AVRMicrocontrollerNov 27, 2002
40+ MHz 5-digit frequency counter with an AVR 2313MicrocontrollerNov 27, 2002
Interfacing DRAM to AT90S8515MicrocontrollerNov 27, 2002
Digital guitar tuner circuit diagramMusicNov 27, 2002
Mini DDS (direct digital synthesizer) using an Analog Devices AD9832 (12MHz maximum frequency)TestNov 27, 2002
Temperature monitor/controller: AVR 2313 / DS1621MicrocontrollerNov 27, 2002
Homemade GPS jammer using a MC145151 frequency synthesizerMiscJan 17, 2011
Neon lamp dimmerLightingNov 17, 2002
2D3 Nixie clock schematic using Atmel microcontrollerMiscSep 13, 2006
Microphone phantom power supplyAudioJan 31, 2003
AD9850 DDS daughterboardTestSep 21, 2006
30M PSK31 Transceiver circuit diagramRFFeb 25, 2003
SOP receiver (PDF)RFOct 30, 2002
SOP direct conversion receiverRFJan 06, 2002
Popular Electronics Ultrasound DetectorMiscJan 01, 2003
PIC micro to ISA bus interfaceMicrocontrollerApr 17, 2004
Balanced microphone preampPreampNov 01, 2002
Machine Independent Parallel InterfacePC 
Navigator 555A radio direction finder (RDF) circuit diagramMiscMay 01, 2004
Signal Tracer and InjectorTestSep 13, 2006
80188XL Engine Tachometer / Race ComputerAutomotiveOct 24, 2002
TDS/PPM Meter for measuring of the amount of salts in a solutionTestMar 29, 2009
Laser Modem with an Arduino MicrocontrollerLaserNov 13, 2010
24" Wall ClockTiming 
Linuxstamp general purpose processor module based on Atmel AT91RM9200Microcontroller 
PG31 GPS RS232 GPS development boardPC 
PG31 GPS RS232 USB development boardPC 
PointLess LED Array - A 8 by 8 array displays something using POVLED 
A "persistence of vision display" (POV display) using LEDsLED 
PC to microcontroller communications using power from the PC serial portMicrocontroller 
RS232 RS485 USB Converter BoardPC 
PalmPilot turbo boost guage interfacePDAApr 27, 2003
1.5V iPod Microphone (PDF)PDASep 25, 2009
Inverter for fluorescent lights as published in Silicon Chip Magazine February 1991 (PDF)LightingAug 18, 2009
Solar switching regulator as published in Silicon Chip Magazine January 1994 Part 1/2 (PDF)SolarAug 18, 2009
Solar switching regulator as published in Silicon Chip Magazine January 1994 Part 2/2 (PDF)SolarAug 18, 2009
LDR light/dark activated relay switchControlJun 17, 2003
Dual Voltage Controlled Oscillator w/ModulatorAudioJun 08, 2002
Spring reverbMusicJun 08, 2002
MS Stereo DecoderAudioJun 08, 2002
Drum percussion sensor schematicsMusicMar 05, 2009
2 Note Ribbon ControllerMusicMar 05, 2009
4 Bit Digitizer / flash ADC using discrete componentsData AcquisitionMar 05, 2009
Using the Hot Springs Reverb reverberation unitMusicMar 05, 2009
midi2cv8 to Drum Tone Board ConnectionsMusicMar 05, 2009
Practical MS Decoder CircuitMusicMar 05, 2009
Drum Tone OscillatorsMusicMar 05, 2009
Theremax Theramic Circuit SchematicMusicMar 05, 2009
Touch switchesMiscMar 05, 2009
Vocal zapperMusicJun 08, 2002
Headphone monitor ampAmplifiersJun 08, 2002
RIAA Equalized Stereo Phono PreampAudioJun 08, 2002
Theremin controllerMusicJun 08, 2002
Touch SwitchesControlJan 26, 2001
6090 digital decoder schematicsControlOct 30, 2002
White LED circuitsLEDOct 13, 2002
Electroluminescent Receiver Kit includes circuit diagramRF 
Receiver based on NE602RFJan 26, 2001
Build your own UFO Bino-Scope unit - upgrade binoculars to become a photosensitive bino-scopeMisc 
Controlling your SLR Camera from an IpodPhotoMay 09, 2010
Deriving power from Lego NXT motor port AModels 
External power supply for Lego NXTModels 
Color sensor circuitMisc 
Wire guidance sensorModels 
GP2D12 distance sensorModels 
Infrared lampIR 
Laser Target Finder SensorLaserOct 06, 2006
Lego compatible, compact rotation sensorModels 
DC40 - 40M Direct Conversion receiverRFOct 08, 2009
SSB linear amplifier made from a bunch of 2N2218 transistorsRFOct 08, 2009
Homebrew signal generator tunable from 3 to 30 MhzTestOct 08, 2009
Simple Dual Band SSB Transceiver (20/40 meters)RFOct 08, 2009
PASCO scientific model SF-9211 stroboscope schematic (PDF)Misc 
Microchip PIC ICD (in-circuit debugger)MicrocontrollerJun 18, 2003
Variety of circuits for RS232 to TTL Signal ConversionMicrocontroller 
Variety of circuits for TTL to RS232 Signal ConversionMicrocontroller 
Smooth, fast, strong and cheap stepper motor controller using a PIC microControlNov 04, 2011
Tony Nixons Pocket Programmer (PIC)MicrocontrollerOct 13, 2002
Simple switching power supplyPowerJul 10, 2002
Selection of PWM driver circuits for electric DC motorsControlNov 05, 2009
PicoWeb V5.1 (AT90S8515) tiny web serverMicrocontrollerJan 31, 2003
RDS EncoderAudioMar 27, 2009
Mass storage and printer interface for the FX-700P calculatorPDA 
MP3 Player circuit schematicMusicMay 30, 2007
Atmel 89C2051 In-Circuit Programmer SchematicMicrocontrollerJun 20, 2004
8051 Development System Circuit BoardMicrocontrollerSep 13, 2006
8051 Development System Circuit BoardMicrocontrollerOct 23, 2002
8051 Development System Circuit BoardMicrocontrollerAug 14, 2002
50W audio power amplifier circuit diagramAmplifiersJun 20, 2004
CCD linear image sensor to PC parallel interfacePCJun 20, 2004
MIDI drum machine projectMusicJun 20, 2004
MIDI Drum Machine Analog Input SchematicMusicApr 27, 2003
Microprocessor using Xilinx FPGAMicrocontrollerJun 20, 2004
Arduindo based Appliance Remote ControlControlJun 20, 2010
Online thermometer based on an ArduinoData AcquisitionJun 20, 2010
PS/2 Keyboard Or Mouse based on an ArduinoPCJun 20, 2010
RFID Access Control System based on an ArduinoAlarmsJun 20, 2010
Oscilloscope / Logic Analyzer based on an ArduinoTestJun 20, 2010
Arduino Based Security / Automation SensorsAlarmsJun 20, 2010
Arduino speech sythesizerMicrocontrollerJun 20, 2010
Arduino based Time-Lapse Camera ControllerPhotoJun 20, 2010
Interfacing an LCD touch control panel to an ArduinoMicrocontrollerJun 20, 2010
Vehicle Telemetry Platform based on an ArduinoAutomotiveJun 20, 2010
Virtual USB Keyboard based on an ArduinoPCJun 20, 2010
Arduino based water flow guageData AcquisitionJun 20, 2010
Water Tank Depth Sensor based on an ArduinoData AcquisitionJun 20, 2010
Weather Station Receiver based on an Arduino and 433MHz RF receiver moduleData AcquisitionJun 20, 2010
Temperature controlled based on AT89CX051MicrocontrollerJan 26, 2001
Sallen-Key Active Butterworth High Pass Filter Calculator and circuit diagramFilterJan 16, 2010
Sallen-Key Active Butterworth Low Pass Filter Calculator and circuit diagramFilterJan 16, 2010
MIDI Pedalboard encoder circuit diagram and background informationMusic 
Tone Filters for Electronic Organs (PDF)Music 
30M Direct Conversion Receiver ProjectRF 
Active Antenna ExperimentsRF 
Low Power Audio Amp ExperimentsAmplifiers 
Cascode 7 Experimental ReceiverRF 
CMOS Logic ExperimentsMisc 
More Discrete BJT, Low Power AF Amp ExperimentsAmplifiers 
Discrete Component Audio-Frequency RC FiltersFilter 
75 Meter QRP SSB TransceiverRF 
Selecting of LED projects including a flashing Christmas treeLED 
Fun with LEDs - a variety of LED flahser projectsLED 
440 Hertz Peaked Low Pass Audio Filter ExperimentsFilter 
Miscellaneous Circuits for Idea PurposesMisc 
Astable Multivibrator Projects / Circuit diagramsTiming 
Junk Box NDB Low Pass FilterRF 
Tuning VFOs With A PN-JunctionTiming 
Popcorn Direct Conversion Main FrameRF 
40 Meter Popcorn Superhet ReceiverRF 
RF preamp circuit diagramsRF 
Some experiments with active or voltage probe antennas (VPA)RF 
MF and HF Receive Antenna SplitterRF 
Medium Frequency TRF ReceiverRF 
QRP transmitter circuit diagramsTransmitters 
40 Meter Band Direct Conversion experimental receiverRF 
Wee Willy 75 Meter DSB Transceiver ProjectRF 
10 MHz WWV Receiver circuit diagramRF 
Cascode Hybrid-Based WWV Receiver for 5 MHzRF 
40m band direct conversion receiverRFJan 06, 2002
80m band direct conversion receiverRFJan 06, 2002
AC Power MeterPower 
Remote Motor ControllerControl 
Precision Frequency MarkerTest 
Simple Inductance MeterTest 
Regenerative Short Wave RadioRF 
Sleep TimerTiming 
Super VXOTiming 
Homebrew 20m CW TransceiverRF 
Homebrew 30m CW TransceiverRF 
Homebrew 40m CW TransceiverRF 
Homebrew 6m SSB/CW TransceiverRF 
Homebrew 6m DSB TransceiverRF 
TV RGB signal output from a SVGA graphics cardVideoApr 14, 2003
High Precision GPS/TV controlled Reference OscillatorTimingMay 01, 2004
u-Blox GPS receiver boardMiscMar 23, 2003
I2C LCD interfaceMicrocontrollerMay 01, 2004
TV based Receiver for a Standard Frequency GeneratorTimingMay 01, 2004
FPGA Based ADS-B Receiver and DecoderRFDec 09, 2010
ADMS programming Cable for the Yaesu FT50, VX1 and VX5PCMay 07, 2010
Radio Interface Box for the Motorola Radius GP300PCMay 07, 2010
PG4S programming Cable for the Kenwood TM-V7 and TM-G707PCMay 07, 2010
Laptop Computer Serial Port Power BoosterPCApr 12, 2001
SPDIF RCA to (Optical + RCA) AdapterPCMay 07, 2010
136 kHz direct conversion receiverRFJan 06, 2002
Chebyshev / Butterworth filtersFilterJun 13, 2002
AFSK 1200 Modem based on PIC16C620MicrocontrollerJul 10, 2002
PicCon - Hidden Radio Transmitter ControllerMicrocontrollerJul 10, 2002
Audible S-MeterRF 
40 Segment LED S-Meter circuit diagramRF 
Bi-Directional 2.4 GHz One Watt AmplifierRFJun 13, 2002
Bi-Directional 900Mhz One Watt AmplifierRFJun 13, 2002
20 Watt GaAaFET Power on 2.3 GHzRFJun 13, 2002
1 Watt 2.3 GHz RF Amplifier Using a MRF2001RFJun 13, 2002
One Watt 2.45 GHz Linear Amplifier using RF Micro Devices RF2126RFOct 31, 2002
VCR Tuner Based RF Spectrum Analyzer SchematicTestSep 21, 2006
2.3 GHz Power AmplifiersRFJun 13, 2002
2304 and 3456 MHz Power AmplifiersRFJun 13, 2002
LCD frequency counter (PIC16F84)TestNov 29, 2002
AD9852 DDS schematicTimingFeb 14, 2003
High Frequency VCO Design and SchematicsRFOct 25, 2014
Dopler RDF (radio direction finder) circuitRF 
Biquad Active Bandpass Filter SchematicFilterNov 01, 2002
VFO from 2001 ARRL Handbook, page 17.74RFNov 01, 2002
VFO from 2001 ARRL Handbook, page 14.20RFNov 01, 2002
Various sound card interfacing circuit diagramsPC 
Assorted relay control circuitsControlMar 18, 2003
Assorted computer interface circuitsPCMar 18, 2003
Assorted digital circuitsMiscMar 18, 2003
Basic opamp circuitsMiscMar 18, 2003
Assorted LED circuitsLEDMar 18, 2003
Miscellaneous simple circuitsMiscMar 18, 2003
Assorted power source and control circuitsPowerMar 18, 2003
Assorted RF circuitsRFMar 18, 2003
Assorted telephone circuits (ring generator, in-use indicator, audio interface)TelephoneMar 18, 2003
PIC16F84 tone generator with source codeMicrocontrollerMar 01, 2003
PIC16F84 tone generatorMicrocontrollerJul 10, 2002
PIC16F84 tone generator (6-Bit)MicrocontrollerJul 10, 2002
14MHz SSB 10mW TransceiverRFFeb 24, 2003
Decimal DDS Signal GeneratorTiming 
Apple II/II+/IIe IDE Drive InterfacePCOct 31, 2002
Circuits to transmit and demoludate RF / video signals over fibre optic cableVideo 
Space invaders game using PIC microcontrollerGamesOct 06, 2006
High quality exponential VCAAmplifiersApr 17, 2004
VLF radio receiver schematicRFApr 17, 2004
VLF Upconverter for Shortwave ReceiverRFSep 13, 2006
Accelerometer SchematicData AcquisitionOct 31, 2002
Basic Vox CircuitRF 
Build A 100Khz Crystal CalibratorTiming 
Build A Simple Rechargeable CMOS BatteryPower 
Variable Bandwidth CW FilterRF 
Simple electronic keyerMisc 
An Inexpensive Tone EncoderRF 
Build A High Performance Voltage Regulator From Discrete ComponentsPower 
Thermal cooling fan controllerControl 
FM Morse Code KeyerMisc 
12 Volt Gel Cell Charger circuit diagramPower 
Selection of Integrated Circuit Audio AmplifiersAmplifiers 
Improved PL tone decoderAudioJan 26, 2001
Easy Morse Code Keyer CircuitMisc 
Build A 10 Amp 13.8 Volt Power SupplyPower 
Adjustable Voltage Regulator using a 7805 or other fixed linear voltage regulator instead on LM317Power 
5 watt, 80 meter QRP CW TransceiverRFJun 08, 2002
Simple electronic S meterTest 
Audio Speech ProcessorAudio 
CW Tone KeyerMisc 
Potpourri of Transistor Audio Amplifier CircuitsAmplifiers 
40 Meter, 5 Watt QRP Transmitter circuit diagramTransmitters 
Using Pass Transistors Beef Up Voltage Regulator current outputPower 
R/C digital camera controllerModelsMar 01, 2003
Digital Call Sign AnnunciatorMiscJun 09, 2002
R/C helicopter cameraModelsOct 30, 2002
Monitor output from Motorola Oncore GPS engine in HP Z3801A in GPS Disciplined OscillatorMiscMay 01, 2004
16 Watt audio amplifier using pair of 8 watt LM383 audio amplifier chipsAmplifiersJan 26, 2001
8 watt amplifier circuit diagramAmplifiersJan 26, 2001
Magnetic cartridge amplifierAudioJan 26, 2001
Electret mic amplifierPreampJan 26, 2001
Audio preamplifierPreampJan 26, 2001
LM358 preamp circuit diagramAudioJan 26, 2001
Sound detector circuit diagramAudioJan 26, 2001
Tone detector circuit diagramAudioJan 26, 2001
Tone generator circuit diagramAudioJan 26, 2001
Warbler siren circuit diagramAudioJan 26, 2001
40khz IR Tester circuit diagramIRJan 26, 2001
555 timer 40khz IR OscillatorIRJan 26, 2001
Basic IR detector / emitter circuit diagramIRJan 26, 2001
Ultrasonic switch transmitter and receiver circuit diagramMiscJan 26, 2001
12 volt battery monitor circuit diagramPowerJan 26, 2001
12 volt power supply circuit diagramPowerJan 26, 2001
5 volt power supply circuit diagramPowerJan 26, 2001
Battery voltage monitor circuit diagramPowerJan 26, 2001
LM3914 battery monitor circuit diagramPowerJan 26, 2001
Multiple voltage power supplyPowerJan 26, 2001
Voltage doubler using a 555 timerPowerJan 26, 2001
Voltage inverter using a 555 timerPowerJan 26, 2001
Miniature FM transmitter circuit diagramTransmittersJan 26, 2001
Sensitive FM transmitter circuit diagramTransmittersJan 26, 2001
Simple RF transmitter circuit diagramTransmittersJan 26, 2001
1.5 volt tracking transmitter circuit diagramTransmittersJan 26, 2001
Tracking transmitter circuit diagramTransmittersJan 26, 2001
Speech Amplifier BoxAmplifiers 
Mini-MosFet Audio AmplifierAmplifiersMar 05, 2009
Compact DJ stationMusicMar 05, 2009
Plant Watering Watcher (moisture meter)Misc 
Automated crib light circuit diagramLighting 
Sound pressure level meter circuit diagramAudio 
Sensor Electronic Tracker with H-Bridge DriveSolarJun 07, 2002
Sensor Electronic Tracker with Simple Solar Charge ControllerSolarJun 07, 2002
Solar tracking control systemSolarNov 16, 2002
LED7 solar tracker circuit diagramSolarNov 16, 2002
Macrovision removal - includes circuit diagram and background informationVideoJan 01, 2003
Pressure Sensor-Based Altimeter CircuitData AcquisitionApr 27, 2003
Build a good GaAs FET preamp for 2 meters, 222MHz or 440MHzRF 
An Audio Limiter for NBFM useAudio 
Crystal heater / temperature stablization circuit (TXCO)Timing 
An Audio-Noise-Based Voting CircuitAudio 
Low power audio amplifier circuit based on LM386AmplifiersJan 29, 2010
LED dimmer circuitLED 
Build a DIY solar iPod chargerSolarMay 30, 2007
Low-cost bingo game for a TV based on an Atmel microcontollerGames 
CASIO datalogger system based around Microchip PIC microcontrollerMicrocontroller 
Slot car TV cronograph displays the lap times of your model cars on a regular TVModels 
DVD thermometer - display temperature on TV by remotely controlling DVD player by infraredIR 
Video DVM - Display voltage on a TV - based on Atmel AT90S1200 and generates vid signal in softwareVideo 
Wireless alarm system based around Nutchip microcontrollerAlarms 
Smartcard controlled relay circuit based around Nutchip microcontrollerAlarms 
PC based digital thermometer based around a Dallas Semiconductor DS1621PC 
A small collection of quick to build electronic circuit designsMisc 
RF Pad - combination-controlled, fully customizable radio frequency remote controlAlarms 
Scriptable thermometer / thermometric controller based around a COP8-CCR9-PLC44 microcontrollerMicrocontroller 
Ultrasonic parking sonar electronic circuit diagram using transistors and 4000 series CMOSAutomotive 
Electronic circuit diagram of cell phone SMS remote control deviceControl 
Cypress PSoC based digital wallet to record secret codes and passwords securelyMicrocontroller 
An automated, self-recording surveillance camera using an SD memory card for recording digital videoVideo 
Virtual Game System - A game console with a mechanically scanned displayGames 
AVR Color Clock using RGB LEDsLED 
PIC10F200-based electronic diceGames 
PIC16F84-based video game systemGames 
Generate video signals in software using PICVideo 
SX28-based color video game systemGames 
Generate composite color video signals in software using an SX microcontrollerVideo 
DIY Plasma Globe using an automotive ignition coilMisc 
DIY Power Pulse ControllerControl 
DIY Tesla coil - DC Powered with Plasma OutputMisc 
Connecting Multiple SRF08 Sonar Modules to a BS2 (Basic Stamp 2)Models 
Ultrasonic range finder circuitData AcquisitionJun 09, 2002
Circuit diagram for connecting the SRF08/10/235 sonar modules to the BS2p Basic StampModels 
Alphanumeric Led Display ProjectLEDNov 02, 2010
H-Bridge Motor Driver Using Bipolar TransistorsControlAug 12, 2009
Dual fan controller using ATTiny45 microcontrollerControlNov 02, 2010
Standalone LED testerTestNov 02, 2010
DC Motor-Driver H-Bridge CircuitControlJun 09, 2002
Infrared Transmitter Project Implemented on a Solderless BreadboardIRNov 02, 2010
Model rocket launch controllerModelsNov 02, 2010
How to Make a PWM Circuit without a MicrocontrollerControlAug 12, 2009
How to Control LED Brightness with a PWM Circuit using a 74AC14LEDApr 17, 2011
Making an Amplified Color Sensor from an LED and an Op AmpLED 
Schematic and breadboard layout for reversed LED color sensor using an opampLEDAug 12, 2009
Making a FRED photopopperModels 
Simple switching regulator (experimental)PowerNov 16, 2002
RS232 interfaced DVM using a PIC12F675 including source code for CCS C CompilerMicrocontrollerSep 09, 2009
A GPS receiver based frequency standardTimingMar 23, 2003
Build a breadboard power module for integrated circuitsPowerSep 30, 2009
Speaker cabinet simulator - professional-quality frequency response in a DIY-friendly circuitAudioSep 30, 2009
Two channel distortion circuitMusic 
Marshall 18W adapted for use as a distortion stompboxMusicSep 30, 2009
Vox AC-30 Top Boost adapted for use as a distortion stompboxMusicSep 30, 2009
Closer look at the FET booster based on a vintage Fender 12AX7 input stage.Music 
Ampeg SB-12 Portaflex adapted for use as a bass overdrive stompboxMusicSep 30, 2009
Distortion effects using an LM386 audio amplifier ICMusicSep 30, 2009
Two 9v battery-powered amps based on the LM386. Schematic and PCB/perfboard layouts.Amplifiers 
Matchless DC/30 adapted for use as a distortion stompboxMusicSep 30, 2009
Treble Booster/Overdrive including a perf board circuit layoutMusicSep 30, 2009
Schematic of a Rockman-like distortion. Schematic and PCB/perfboard layouts.Music 
Mr. EQ - a simple, yet potent DIY equalizerMusicSep 30, 2009
New clipper circuit diagram (based on TL071 opamp)MusicSep 30, 2009
Versatile FET booster engine. Schematic and perfboard/PCB layouts.Music 
Peppermill overdrive - A simple, transparent overdrive. Schematic and PCB/perfboard layouts.MusicSep 30, 2009
Faux-phaser circuit with LFO and manual (wah pedal) modes. Schematic and and PCB layout.MusicSep 30, 2009
Fender Princeton adapted for use as a distortion stompboxMusic 
Ruby is an "enhanced" version of the Little Gem battery-powered amplifier (LM386 based design)AmplifiersSep 30, 2009
Supro 16T adapted for use as a distortion stompboxMusicSep 30, 2009
Dual parallel buffered effect loops with blend control. Schematic and perfboard/PCB layoutsMusic 
Marshall 100W Super Lead adapted for use as a distortion stompbox. Schematic and PCB layout.MusicSep 30, 2009
An ultra-flexible tonestack with clean boost. Schematic, photo, and PCB/perfboard layouts.MusicSep 30, 2009
Tube Screamer-based overdrive. Schematic and PCB/perfboard layouts.Music 
Umble - A distortion stompbox, inspired by Dumble amplifiers. Schematic and PCB/perfboard layouts.MusicSep 30, 2009
Boogie MkI adapted for use as a distortion stompboxMusic 
Two Transistor Reflex RadioRFAug 17, 2009
LED flasher using 4584 hex inverting Schmitt triggerLEDAug 17, 2009
Sound operated switchAudioAug 17, 2009
Low power audio amplifier using BC109C along with BD679 and BD680 Darlington pairsAmplifiers 
Long duration timer using 4060 12-stage binary ripple counterTimingAug 17, 2009
Infrared headphone system (includes transmistter and receiver schematics along with vero layout)IRAug 17, 2009
Simple stepper motor driver for PC parallel portPC 
Optically isolated TRIAC driverControlAug 17, 2009
Reaction timer using 4013 flip-flop and 4060 12-stage binary ripple counterGamesAug 17, 2009
10 watt audio power amplifier using discrete transistors (includes PCB layout)Amplifiers 
TRIAC based lamp dimmer circuit diagramLightingAug 17, 2009
StroboscopeMiscAug 17, 2009
8049 Spy - read the internal ROM contents of a 8048 or 8049 processorMicrocontrollerSep 25, 2009
MS-DOS EEPROM ProgrammerPCSep 25, 2009
Fluke 8010 / 8012 InterfaceTestSep 25, 2009
6802 Nano computerMicrocontrollerSep 25, 2009
Nikon IR-Remote Control based on Atmel ATtiny13PhotoSep 25, 2009
SAA1064 display module projectLEDSep 25, 2009
SB-Bus Drivers Introduction and Circuit DiagramsPCSep 25, 2009
AVR STK200/STK300 ISP Dongle circuit diagramMicrocontrollerSep 25, 2009
Tiny Eprom SimulatorMicrocontrollerSep 25, 2009
UTP Cable TesterTestSep 25, 2009
PC based biofeedback monitorMedical 
Camera remote control system using Basic StampPhotoMay 01, 2004
Audio Detector CircuitAudioOct 06, 2006
RF Modem Robotics ProjectModelsJan 06, 2002
Real-time Laser Range Finding Vision SystemLaserOct 06, 2006
10Hz - 100KHz D.D.S. Function GeneratorTestSep 21, 2006
RS-232 to TTL cablePCMay 01, 2004
Very basic circuitsMiscJan 26, 2001
Implementing Infrared Object DetectionIRJan 26, 2001
R2T2 Haywire Home StationRFOct 07, 2009
ICOM CI-V interface with RS232 RTS to PTTRFMay 01, 2004
Bat detectorMiscJan 26, 2001
30-Meter QRP Transmitter for Morse CodeTransmittersJan 26, 2001
3rd brake light circuit diagramAutomotiveJan 26, 2001
DC to AC inverter using a 555 timerPower 
555 Timer IC Tester circuit diagramTestJan 26, 2001
555 go / no-go tester circuit diagramTestJan 08, 2002
Dual (postive and negative) 12V power supplyPower 
Active Antenna AA-7 HF/VHF/UHF, 3-3000MHzRF 
Active antenna 1 to 20dB, 1-30 MHz rangeRF 
Active Antenna for AM-FM-SWRF 
FM radio active antennaRF 
Light / dark activated relayControlJan 26, 2001
Touch activated alarm systemAlarmsJan 26, 2001
Current booster for 78nn series voltage regulatorsPower 
Aviation band receiverRF 
Car backup / reversing alarmAutomotive 
12V Lead-Acid Battery Monitor using LM3914PowerJan 08, 2002
Battery Tester for 1.5 and 9VTest 
Charger for gel lead acid batteriesPowerJan 26, 2001
Broadcast-Band RF AmplifierRF 
Bug detector with beep using 7413 or 74LS13RFJan 26, 2001
Bug detector / countersurveillance monitorRF 
Electronic canary doorbellMisc 
12V to 9V car coverter circuit diagramAutomotiveJan 26, 2001
Clock generatorTimingJan 26, 2001
Continuity tester V2 circuit diagramTestJan 26, 2001
Continuity tester circuit diagramTestJan 26, 2001
Coin tosserGamesOct 06, 2006
Compressor-mate power protection for refrigerators, freezers and air conditionersPowerOct 06, 2006
Cut phone line detectorTelephoneJan 08, 2002
DSL / ADSL phone line filterTelephone 
Waterpump Safety Guard for fish pond / fish tankAlarms 
Third brake light pulser circuitAutomotive 
Miniature FM Transmitter #1TransmittersJan 26, 2001
Miniature FM Transmitter #2TransmittersJan 26, 2001
Miniature FM Transmitter #3TransmittersJan 26, 2001
4-transistor transmitter circuit diagramTransmittersOct 06, 2006
FM telephone transmitterTransmittersOct 06, 2006
Electronic dazerMisc 
High voltage DC generatorPower 
High-Voltage Pulse GeneratorPower 
Jacob's LadderMisc 
Lightning bulb - Create an electrical storm in a light bulbLighting 
Negative Ion DetectorMisc 
Negative Ion GeneratorMisc 
Tesla coilMisc 
Solid state tesla coilMisc 
High voltage zappersMisc 
Motorcycle battery chargerAutomotive 
Lamp flasher/dimmerLightingJan 26, 2001
Miniature tracking transmitterTransmittersOct 06, 2006
Motorcycle low battery voltage warning circuitAutomotive 
Morse Code Practice Keyer 1MiscJan 26, 2001
Morse Code Practice Keyer 2MiscJan 26, 2001
Motorcycle brake light flasherAutomotive 
Motorctcle turning signal systemAutomotive 
Automatic 9V NiCad battery chargerPower 
9-pin null modem cablePCJan 26, 2001
Audio preampPreampJan 26, 2001
Logic probeTestJan 26, 2001
Pulse width modudulator using 555 timer ICControlAug 03, 2009
Active Power ZenerPower 
Sound activated relay, V1Audio 
Sound activated relay, V2Audio 
Basic RF oscillatorRFJan 26, 2001
Light sensing RF transmitterTransmittersJan 26, 2001
ScanMate audio activated recordedMicrocontrollerJan 26, 2001
Subcarrier adapter to listen to hidden subcarrier signals on FM radioRF 
Water-level sensorData AcquisitionJan 26, 2001
741 Light SensorMiscJan 26, 2001
Fluid level detectorMiscJan 26, 2001
Solid state relay circuitPower 
Simplest R/C circuitModels 
ThereminMusic 
Touch switch using transistorsMisc 
1.5V tracking transmitter circuit diagramTransmittersOct 06, 2006
Micro-Spy with FETsTransmittersJan 26, 2001
Micro-Spy with USWTransmittersJan 26, 2001
Micro-Spy with TTLTransmittersJan 26, 2001
Wailing alarm sirenAlarms 
Wireless microphoneTransmittersOct 06, 2006
Christmas lights testerLightingOct 06, 2006
555 Timer Tutorial + CircuitsTimingJan 26, 2001
Car Nicad chargerAutomotiveJan 26, 2001
NiCad Discharger for Tx & Rx PacksPower 
Glowplug driver for radio control modelsModels 
Lead acid battery charger with floatPower 
Simple constant current sourcePower 
Solar cell Nicad charger using Maxim MAX639SolarJan 26, 2001
Two tone train hornModelsJan 26, 2001
Low cost Atmel in-system programmerMicrocontrollerApr 17, 2004
Ultra low-cost programmer for AT90S familyMicrocontrollerApr 17, 2004
AVR (AT90S2313) composite PAL colour bar generatorVideoApr 17, 2004
Connecting AT90S2313 with LCD display 2x16 char and 4x4 keypadMicrocontrollerApr 17, 2004
Electronic safety lock based on ATtiny26MicrocontrollerApr 17, 2004
Greek telecard readerTelephoneApr 17, 2004
128x64 LCD Driver for AT90S2313 (ZIP file)MicrocontrollerApr 17, 2004
1-Wire Barometer projectData Acquisition 
Simple pH Meter Circuit, A Low Cost Adapter for Your Digital VoltmeterTestNov 02, 2010
Connecting LED to PIC Micro I/O pins (PDF)MicrocontrollerNov 17, 2002
FCTS ProjectMiscMar 25, 2001
Galvanic isolated CAT & audio interface for amateur radioRF 
Heart rate sensorMedicalOct 06, 2006
Motor walker circuitModelsNov 16, 2002
Zener-based solar engineSolarNov 16, 2002
Morse Code Beacon KeyerRFSep 21, 2006
PC Automatic Power-on CircuitPCMay 19, 2015
Constant Temperature CircuitControlSep 21, 2006
Improved FM Stereo ModulatorRFJul 09, 2002
Count Accumulator for Radiation Levels (CARL)MiscSep 21, 2006
Modifications for CDV700 Geiger CounterMiscSep 21, 2006
40-30 CW Transmitter (Tube based)TransmittersMay 19, 2015
The WB0RIO 6U8A Code Practice OscillatorMiscMay 19, 2015
The House Finch Direct Conversion Tube ReceiverRFMay 19, 2015
The Little Chickadee 6U8A QRP TransmitterTransmittersMay 19, 2015
Magic Eye Tube WavemeterTestMay 19, 2015
WB0RIO Piglet 6U8A Regenerative Receiver (Tube based)RFMay 19, 2015
QRP Antenna TunerRFSep 21, 2006
All-Ears QSK Timing GeneratorTimingMay 19, 2015
Smooth Tone Clickless CW Sidetone GeneratorRFSep 21, 2006
Power Supply for Vacuum Tube ExperimentsPowerMay 19, 2015
Regulated 12V Dual LED LampLEDMay 19, 2015
Regulated Dual 3 Watt White LED LampLEDMay 18, 2015
Regulated 24 Watt Broad Spectrum LED LampLEDMay 19, 2015
Lightning activated camera shutter triggerPhotoAug 17, 2009
TTL Pulse Reading Logic ProbeTestSep 21, 2006
High Fidelity FM Stereo Modulator (Rev E2)RFMay 19, 2015
VXO FM BugTransmittersMay 19, 2015
Big Ear Stereo Parabolic MicrophoneMiscSep 21, 2006
Ultra Low Power LCD IndicatorMiscSep 21, 2006
13 Color LED Rainbow circuit schematicLEDSep 21, 2006
Nine Volt Battery EliminatorPowerSep 07, 2009
Arduino LFO Waveform Generator V2MicrocontrollerMay 19, 2015
Vacuum Tube B+ Delay CircuitMiscMay 19, 2015
Hammonator Organ to Guitar Amp Conversion (tube amplifier)AmplifiersSep 07, 2009
Lil' Tiger Hammond AO-43 Organ to Guitar Amp ConversionMusicMay 19, 2015
Liquidator Tube Phaser/Chorus EffectMusicSep 07, 2009
Voltage Controlled PannerAudioSep 21, 2006
Guitar Reverb Effect Version 2AudioSep 21, 2006
Stereo Audio IsolatorAudioSep 21, 2006
Panner Waveform GeneratorAudioSep 21, 2006
Voltage controlled audio pannerAudioAug 01, 2010
Isolated Telephone Interface (phone tap) for tape recorder, PC sound card etcTelephoneSep 21, 2006
PWM DC Motor Speed ControlPowerSep 21, 2006
PWM Motor Speed Controller / DC Light DimmerControlSep 07, 2009
PWM Motor/Light Controller circuit diagramsControlSep 07, 2009
Microprocessor RS-232 ResetMicrocontrollerSep 21, 2006
18 LED dimmable LED lamp circuit diagramLEDSep 07, 2009
Regulated Dual White LED LampLEDSep 07, 2009
Seven Component Regulated LED LampLEDSep 21, 2006
Buck Mode Switching Regulator for Solar ApplicationsSolarSep 21, 2006
Solar Panel Charge Controller / Low Voltage Disconnect CircuitSolarJul 12, 2001
Solar Panel Charge Controller / Low Voltage Disconnect Circuit (SPC1)SolarSep 07, 2009
DAS1 - 12 Volt 10 Amp Dark Activated SwitchControlSep 07, 2009
High Efficiency 12V White LED DriverLEDSep 21, 2006
12 Volt Differential Temperature ControllerControlSep 07, 2009
Solar Panel Current MeterSolarJul 12, 2001
LED Mood LightLEDJul 12, 2001
Battery Low Voltage BeeperPowerSep 21, 2006
Remote Solar LED lightSolarSep 21, 2006
PWM Motor Speed Controller / DC Light DimmerControlNov 17, 2002
PWM Motor Speed Controller / DC Light DimmerPowerJul 12, 2001
PWM Motor/Light ControllerPowerJul 12, 2001
SCC2 10 Amp Solar Charge ControllerSolarOct 30, 2002
SCC2 10 Amp Solar Charge ControllerSolarSep 07, 2009
12 Volt 20 Amp Solar Charge ControllerSolarSep 21, 2006
Shunt-mode Solar/Wind Charge ControllerSolarSep 07, 2009
Solar Powered Night LightSolarSep 07, 2009
Solar Charged LED FlashlightSolarJul 12, 2001
Self Powered Solar Box FurnaceSolarSep 21, 2006
SPC2 6 Amp Solar Power CenterSolarSep 21, 2006
SPC3 9 Amp in / 10 Amp out Solar Power CenterSolarSep 07, 2009
Solar Powered Reading LampSolarSep 21, 2006
12 Volt Toilet Tank Refiller circuit diagramMiscSep 21, 2006
Low Power LED VoltmeterPowerJul 12, 2001
WGR1 - 12 Volt Wind Generator RegulatorPowerMay 19, 2015
Expanded Scale Battery Volt MeterPowerSep 07, 2009
Stereo Test Tone GeneratorTestSep 21, 2006
Octopus Curve TracerTestMay 19, 2015
Temperature Controlled Nicad ChargerPowerSep 21, 2006
12V, 4-AA Cell Differential Temperature ChargerPowerAug 17, 2009
Motorized Video Camera MountVideoSep 21, 2006
Morse Code Beacon KeyerMiscJan 26, 2001
Constant Temperature CircuitControlJan 26, 2001
Lightning Activated Camera Shutter TriggerPhotoJan 26, 2001
Pulse Reading Logic ProbeTestJan 26, 2001
Micro Power FM Broadcasting CircuitsTransmittersJan 26, 2001
Voltage Controlled PannerAudioJan 26, 2001
PWM DC Motor Speed ControlControlJan 26, 2001
Guitar Reverb PedalMusicJan 26, 2001
AA battery solar chargerSolarJan 26, 2001
Solar Panel Charge Controller / Low Voltage Disconnect CircuitSolarJan 26, 2001
Solar Panel Current MeterSolarJan 26, 2001
LED Mood LightLightingJan 26, 2001
PWM Motor/Light ControllerPowerJan 26, 2001
PWM Motor/Light Controller variantsPowerJan 26, 2001
Low Power LED VoltmeterPowerJan 26, 2001
Temperature Controlled NICD ChargerPowerJan 26, 2001
Circuit for interfacing a relay / solenoid to a PC based on a 2N7000 FETPCSep 01, 2009
Variety of receiver converter projectsRFApr 24, 2001
One transistor FM receiverRFApr 24, 2001
42 Mc Band to 88 Mc Band (retrofit converter) ProjectRFApr 24, 2001
RF noise bridge for HFRF 
LC meter with LCD display for readoutTest 
160m mini portable End Fed Half Wave Tuner - MkIIRF 
RF/SS Handie Hopper Transmitter SchematicTransmittersOct 23, 2002
AT90S8515 experimenter boardMicrocontrollerNov 27, 2002
DIY shutterglasses controllerGamesJan 26, 2001
Stop Action 3D-Photography using an audio flash triggerPhoto 
Remote control uses an IR receiver chip to receive the IR signal from the remoteIR 
How to construct Garmin GPS receiver interface cablesPCMar 23, 2003
Vacuum Tube Microphone PreampPreampNov 01, 2002
FCD (Fuel Cut Defencer)AutomotiveOct 30, 2002
Jasmin floppy disk controller schematicsPCSep 13, 2006
Weather station with pressure reading, relative humidity, indoor & remote temperature readingMisc 
Battery Charger IdeasPowerAug 14, 2002
Crystal radio circuits including diode performance comparisonRFMar 10, 2003
Game Show TimersGamesOct 06, 2006
Induction receiver for tracing wiring behind walls, hearing lightning and other electric dischargesMisc 
Refrigerator Door AlarmAlarms 
Rain alarm / rain detectorAlarms 
Homebuilt video digitizer Mark IVideoFeb 01, 2003
Homebuilt video digitizer Mark IIVideoFeb 01, 2003
Daisy MP3 player projectMusic 
Simple open source MP3 player with SD/MMC memory card supportMusicMay 30, 2007
Archery timerGamesAug 14, 2002
Windmill DIY Analog MPPT (maximum power point tracker) CircuitPowerMar 09, 2012
CO2 controller for planted tanksControlJan 26, 2001
Ultrasonic Distance Measurement With the MSP430 (PDF)Microcontroller 
Texas Instruments collection of differential op-amp circuits (PDF)Misc 
Texas Instruments collection of buffer op-amp circuits for ADCMisc 
Simple MPPT-Based (maximum power point tracker) Lead Acid Charger Using bq2031 (pdf)SolarMar 09, 2012
Wireless local network for PalmPilot (large PDF)PDANov 16, 2002
FET Preamp CablePreampNov 01, 2002
Building a Hardware Random Bit GeneratorMisc 
Monostable multivibratorTimingJan 01, 2003
Altec 1564A Preamp Power SupplyPreampSep 13, 2006
Neumann U67 microphone preamp power supplyPreampSep 13, 2006
Midibox 64MusicAug 09, 2002
TTL to RS232 adapter using 2N3906 / 2N3904 transistorsMicrocontroller 
Highly sensitive and selective Field Strength Meter systemTestApr 14, 2011
Wide dynamic range Field Strength Meter mark ITestApr 14, 2011
Wide dynamic range Field Strength Meter mark IITestApr 14, 2011
RS232 - Lowe HF-225 interfacePCNov 21, 2002
Addressable ADCData AcquisitionJul 24, 2002
Battery CharacterizerPowerJul 24, 2002
Delayed shutter control for Kodak DC-20MiscJul 24, 2002
Combination Lock (PIC16F84)AlarmsJul 24, 2002
PIC16F876 DataloggerMicrocontrollerJul 24, 2002
R/C Emergency locator alarmModelsJul 24, 2002
Combination lock for car liftgateAutomotiveJul 24, 2002
Morse code displayMiscJul 24, 2002
Kodak DC-20 camera interface (PIC12C509)PhotoJul 24, 2002
Kodak DC-20 camera interface (PIC16F84)PhotoJul 24, 2002
Angelfire rocket GPS payloadModelsSep 10, 2006
Relay circuit for relay control via an RS232 portControl 
Serial to parallel converter - connect a large number of digital outputs to a PC parallel portPC 
Micro-step driver - connect a bipolar steppe motor to a PC through the parallel portControl 
PC parallel port eight DC power switch cam driver two unipolar stepper motors, lights etcPC 
80 Metre CW beacon / transmitter circuit diagramTransmittersSep 01, 2009
ADXL202 break-out boardData Acquisition 
Wisp628 ISP Microchip PIC ProgrammerMicrocontrollerAug 09, 2002
WLoader - PIC16F877 application loader / bootloaderMicrocontrollerMay 01, 2004
Lead/acid battery chargerPower 
Simple RIT circuit based on a 2N7000 FETRFSep 01, 2009
Circuit for temperature stabilization of a MTP3055E MOSFETMiscSep 01, 2009
Digital signal processor (DSP) for radio communicationsFilterJun 06, 2003
Simple LED Constant Current Lighting CircuitLEDJul 11, 2012
56K RF Modem circuit diagramRFJan 06, 2002
29.85 MHZ bandpass filter schematicFilterNov 01, 2002
29.85 MHZ notch filter schematicFilterNov 01, 2002
Altec 428B Microphone Preamplifier schematicPreampSep 13, 2006
API 321 mic preamp schematicPreampSep 13, 2006
RCA BA-1A two-stage preamp schematicPreampSep 13, 2006
RCA BA-21A preamplifier schematicPreampSep 13, 2006
RCA BA-31A preamplifier schematicPreampSep 13, 2006
Poor man's analog to digital converter (ADC) using a 2N222 transistor and a few passives (PDF)Microcontroller 
GPS-based universal clock generatorTiming 
Pic-Plot GPIB to RS-232 converterPC 
Kenwood TH-D7 NMEA GPS bug fixMisc 
5 tubes SSB QRP Transceiver for 20m Ham bandRF 
Pic-Plot2 GPIB to USB converterPC 
Nixie clock (PIC16F876)MicrocontrollerJun 18, 2003
Homemade scope clock using a DG7 tube and a Microchip PIC16F876Timing 
ADC logger 6ch Measurent and serial port logger with wireless longrange linkData Acquisition 
Atmel Mega32 8ch Analog signal measure loggerData Acquisition 
Atmel Mega88 Dual Temperatur meterMicrocontroller 
Atmel Mega88 Temperatur meter, Type K sensor, Heat set and regulatorMicrocontroller 
PA fan temperature controlled speed motor speed controllerControl 
PIC16 DemoKit3 with programmer and displaysMicrocontroller 
144.000 Mhz CW TransmitterTransmitters 
2m (144MHz) Dual Gate FET Low Noise AmplifierRF 
Car Timer with Atmel ATiny45 to automatically turn of accessories to prevent flat batteryAutomotive 
VCO covers 300MHz to 500MHz based on Maxim MAX2608 VCOTiming 
Digital Wattmeter, measures from nanowatts to kilowatts using AD8307, PIC16F876, LCD DisplayTest 
200 Watt Modified PC Power Supply 13.5 Volt 14 AmpPowerJul 24, 2002
SWR Bridge 1 to 1000 Mhz (1GHz)Test 
Homemade Water Drain Pump controllerControl 
Universal Exposure Timer and Event CounterPhoto 
Computer Sound Port Shutter TesterPhotoAug 17, 2009
Field strength meter for the 137 kHz bandTestMay 01, 2004
Five Tube Stereo AmplifierAmplifiersSep 13, 2006
Dual stepper motor drivers using UDN2540ControlJul 03, 2011
PWM DC motor driver and control with SG3525ControlJul 03, 2011
Kenwood TR-7950 manual & schematics (PDF)RFSep 10, 2006
Battery Meter for Pinball MachinesGames 
5 Zone alarm circuit circuit schematicAlarmsJan 26, 2001
Miniature loop alarmAlarmsJan 26, 2001
Novel BuzzerAlarmsNov 27, 2002
Gate alarm circuitAlarmsJan 26, 2001
Modular Burglar AlarmAlarmsNov 27, 2002
Motorcycle alarmAlarmsNov 17, 2002
Enhanced 5 Digit Alarm KeypadAlarmsNov 27, 2002
Enhanced 4 Digit Alarm KeypadAlarmsNov 27, 2002
RF AlarmAlarmsNov 27, 2002
Single Zone AlarmAlarmsNov 27, 2002
Water Activated AlarmAlarmsNov 27, 2002
Water level alarmAlarmsNov 17, 2002
2W Audio Amplifier using BD139 and BD140 transistorsAmplifiersJan 26, 2001
3-Band audio graphic equalizerAudioJan 26, 2001
6-Input mixer circuit diagramAudioJan 26, 2001
Computer microphonePCJan 26, 2001
Doorphone intercomAudioJan 26, 2001
ECM Mic preampPreampJan 26, 2001
Hi Fi preampPreampJan 26, 2001
Stereo audio line driver for running audio over long distance cablesAudioJan 26, 2001
Variable notch filter with both high and low pass filtersFilterSep 13, 2006
Peak reading audio level meter using CA3140 opampAudioJan 26, 2001
Tone control circuit schematicAudioJan 26, 2001
TDA2030 8 Watt amplifierAmplifiersJan 26, 2001
Infra Red SwitchIRNov 27, 2002
IR remote control extenderIRJan 26, 2001
IR Remote Control Extender Circuit (Mark 2)IRNov 27, 2002
IR Remote Control Extender Circuit (Mark 3)IRNov 27, 2002
Infra Red wired Repeater circuit to control appliances from a remote locationIR 
IR LinkIRNov 27, 2002
Multi Rocket LauncherModelsNov 27, 2002
Model rocket launch controllerModelsNov 27, 2002
Doorbell for the deaf that provides a delayed visual indication when a doorbell switch is pressedMiscNov 27, 2002
Electromagnetic field detectorMiscJan 26, 2001
Hot Water Tank Level IndicatorControlNov 27, 2002
Insect Repellant (22KHz audio oscillator)MiscNov 27, 2002
High Quality IntercomMiscNov 27, 2002
Basic infrared link for audio communication over distances up to 3 metresIRFeb 05, 2010
Magnetic Gun.MiscNov 27, 2002
Magic Wand Conjuring TrickGamesNov 27, 2002
Single chip metal detecor with a range of a few inches based on CS209AMisc 
Neon desklampLightingNov 27, 2002
Perimeter monitorAlarmsJan 26, 2001
Quiz game circuitGamesNov 27, 2002
Speaker Microphone CircuitAudioNov 27, 2002
Static Electricity / Negative Ion DetectorMiscNov 27, 2002
Temperature monitor using 741 opampControlJan 26, 2001
E.S.P. Conjuring TrickGamesNov 27, 2002
Ultrasonic dog whistleMiscJan 26, 2001
Electronic canary sound effectsAudioJan 26, 2001
Electronic metronomeMusicJan 26, 2001
Electronic sirenAudioNov 27, 2002
Sound Effects GeneratorMusicNov 27, 2002
Sound Effects Generator 2MusicNov 27, 2002
12V 30A power supply circuit diagramPowerJan 26, 2001
Dual regulated power supplyPowerJan 26, 2001
Fuse blown indicatorPowerJan 26, 2001
Gyrator circuitPowerJan 26, 2001
Variable power supplyPowerJan 26, 2001
LM317 Regulator CircuitPowerNov 27, 2002
Nicad battery chargerPowerJan 26, 2001
Regulated 12V supplyPowerJan 26, 2001
Unregulated power supplyPowerJan 26, 2001
Camera switching circuit to run multiple cameras with one monitorVideo 
Cold activated switch (frost alarm)AlarmsJan 26, 2001
Voltage comparator switchControlJan 26, 2001
Dark activated switchControlJan 26, 2001
DC Push Button Motor Control CircuitControlJan 26, 2001
Push Button Switch DebouncerTimingJan 26, 2001
Digital combination lock circuit diagramAlarmsJan 26, 2001
Alarm control keypadAlarmsNov 27, 2002
Light detectorControlJan 26, 2001
Electronic night lightLightingJan 26, 2001
DC Motor Reversing CircuitControlNov 27, 2002
Sound operated switchControlJan 26, 2001
4 Digit Keypad SwitchControl 
Simple keypad operated switchControl 
Multi wire cable tester that handles up to eight conductorsTestNov 27, 2002
Connection tester for checking solder joints and other connectionsTestNov 27, 2002
EMF field probe (electromagnetic field probe) covering up to 100kHzTestJan 26, 2001
Function generator based on 8038PCD function generator ICTestJan 26, 2001
IR remote control testerIRJan 26, 2001
Logic probe based on CMOS 4001 chipTestJan 26, 2001
Square wave oscillator using CMOS 4011 NAND chipTimingJan 26, 2001
Zener diode tester based on a 555 timerTestJan 26, 2001
5 to 30 Minute Timer circuit diagramTimingNov 27, 2002
NE555 Basic MonostableTimingNov 27, 2002
Commodore 64 Video Modulator 251025 SchematicsVideoNov 16, 2002
Commodore 64 Video Modulator 251696 SchematicsVideoNov 16, 2002
Computerized Infrared RemoteIRAug 27, 2003
Darkroom timer using PIC16F84AMicrocontrollerMar 07, 2009
Lego Mindstoms IR Link PIC transceiverGamesMar 07, 2009
Lego Mindstorms Double Rotation SensorGamesMar 07, 2009
LC filter design on-line calculatorFilterJun 13, 2002
Envelope generator ADSRAudio 
Scaling ADXL50 accelerometer outputMiscJan 26, 2001
Wireless Electrocardiogram MonitorMedicalOct 06, 2006
Beat Tracking StrobeAudio 
Sniper tag laser beam detectorLaserOct 06, 2006
Galvanic Skin Response (GSR) CircuitMedical 
Accurate Digital LC Meter based on a PIC16F84TestFeb 20, 2013
Simple high current pulsed laser driver using an avalanche transistorLaser 
Common Ground for Older VPW OBD CircuitAutomotiveMay 01, 2004
USB to parallel port converter using Cypress CY7C68013A-56PVXCPC