There are 208 circuit schematics available. Last circuit added on Tuesday, 19 May 2015.

CircuitCategoryDate AddedOK?
Simple moisture indicatorMisc 
Two-tone doorbell using 555 timerMisc 
omentary High Voltage Arc Circuit - can be used to Ignite a barbeque or a Gas in a Potato GunMisc 
Simple BFO metal detector using 2N3906 and 2N3904 transistorsMiscMay 30, 2007
Cat or Dog Detector - can be used to control entry on a Cat or Dog DoorMisc 
Fish caller circuitMiscSep 23, 2009
Powerful stun gun / taser circuit diagramMiscSep 23, 2009
Ultrasonic sound detector / snifferMiscSep 23, 2009
Air flow detectorMisc 
Simple Frequency Reader for conversion VFOsMiscOct 05, 2009
Eddie's Composting Loo fan controllerMiscMar 09, 2012
Touch operated Band switch for Radio SetMiscOct 25, 2014
Digital Remote ThermometerMiscJun 26, 2009
Capacitive SensorMiscJun 26, 2009
Mains Remote-Alert - Remotely operates beeper and/or a LED via mains supply lineMiscJun 26, 2009
Touch activated switch using CD4011 CMOS NAND gateMiscJun 26, 2009
Voice activated switch (VOX) circuit diagramMiscJun 26, 2009
UltraSonic RadarMiscJun 26, 2009
Nocturnal Animals WhiskerMisc 
Insect RepellantMiscSep 17, 2009
Digital Radar SpeedometerMiscOct 21, 2009
Electromagnetic Field Probe with Meter Output using an LF351 opampMiscOct 19, 2009
Beat Balance Metal DetectorMisc 
Coil Coupled Operation Metal DetectorMiscNov 10, 2009
Missing Pulse Detector Circuit with 555 ICMiscOct 03, 2013
Chaos generatorMiscJan 26, 2001
A Two-Way Morse Practice SetMisc 
Voltage Comparator Information And CircuitsMiscApr 27, 2003
Visible and Infrared Light DetectorsMisc 
Light Activated Detector Circuit (LM393/LM555)MiscSep 10, 2006
10 GHz CW Radar based on a X-band GunnplexerMisc 
GoldPic 3 Pulse Induction Metal Detector (has electronic kit available)MiscMay 30, 2007
Photodiode primer and interface circuit diagrams including photovoltaic and photoconductive modesMiscMar 04, 2010
Full-duplex doorphone with 3 wires connectionMiscMar 23, 2003
G Strain energy absorberMiscJan 01, 2003
Amateur weather station to APRS interface ALWXI-01MiscOct 07, 2009
Switch debouncer circuits including transistor, CMOS logic and a 555 timer based designMiscJan 31, 2010
Interesesting circuits using diodes ideal for education or introductory courses on electronicsMiscFeb 20, 2010
Selection of run circuits to experiment with the 4017 CMOS decade counter chipMiscFeb 26, 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
Marshmallow Bazooka with a PIC12F615 based capacitor discharge ignition systemMiscMay 16, 2010
Touch sensistive touchpad based on a PIC16F627A microMiscMay 24, 2010
Electric cockroach zapperMiscMay 24, 2010
Home-Built Magnetic LevitatorMisc 
Project for experimenting with magnetic levitationMisc 
FET based metal detector using MPF102 / J310 BF998 FETsMiscMay 30, 2007
Ultrasound detectorMiscSep 13, 2006
Build Your Own Video-Rate 2-photon MicroscopeMiscSep 25, 2009
Sony RS-422 ADAT sync cable pinoutMiscSep 10, 2006
Garmin Foretrex 101,201, Forerunner 101,201 to Serial DB9 cable schematic pinoutMiscSep 10, 2006
Simple DTMF Repeater Controller using PIC16F84Misc 
Build a Simple Bat DetectorMiscJan 08, 2014
Capacitance to Voltage conversionMisc 
Biasing Op-Amps into Class AMiscJan 01, 2003
Bleeper box for time referenceMiscMay 01, 2004
Random noise generatorMiscJan 26, 2001
Analog pulse counterMiscAug 12, 2001
Analog opto-isolatorMiscAug 12, 2001
Pulse width modulators (PWM)MiscAug 12, 2001
Pulse width to voltage converterMiscAug 12, 2001
Air flow detector using an incandescent lamp to detect airflowMisc 
Simple Lie DetectorMiscSep 01, 2009
Low Voltage AlarmMiscSep 01, 2009
Rain DetectorMiscSep 01, 2009
Magnetic levitation deviceMiscAug 14, 2002
Tesla power receiverMiscJan 06, 2002
1.9 Kilojoule Coil GunMiscNov 16, 2010
A spark throwing tesla coil made entirely of garbageMiscNov 16, 2010
Basic Homebuilt Discrete DTL gate circuits (Diode Transistor Logic)Misc 
Lazer Tag Equipment ModificationsMiscMar 23, 2003
Inexpensive APRS Weather StationMiscAug 14, 2002
Two-component metal detector using a 4093Misc 
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 
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 
1uS light pulse descriminator plus F to V converter (PDF)MiscJan 26, 2001
Broadband 2MHz optical fiber receiver (PDF)MiscJan 26, 2001
Modulated light receiver circuit (PDF)MiscJan 26, 2001
1uS light pulse receiver plus post amp (MISC)MiscJan 26, 2001
Broadband 5MHz optical fiber receiver (PDF)MiscJan 26, 2001
High-speed 75MHz light receiver (PDF)MiscJan 26, 2001
Basement doorbell beeper (PDF)MiscJan 26, 2001
Time to dust indicator - battery powered dust indicator (PDF)MiscJan 26, 2001
Low-power optical interrupter (PDF)MiscJan 26, 2001
Simple nitrogen spark generator (PDF)MiscJan 26, 2001
Simple DIY BFO metal detectorMiscJun 27, 2010
Op Amp Comparator with Hysteresis with SPICE simulationMiscMar 26, 2011
Op Amp Precision Half-wave Rectifier including SPICE simulationMiscMar 26, 2011
Single-Supply AC Inverting Op Amp amplifier with SPICE simulationMiscMar 26, 2011
Hacking the Hot Wheels Radar Gun - includes circuit of analog front endMisc 
Ultrasonic transducer oscillator circuitMiscJan 26, 2001
Build logic gates using discrete partsMiscJan 26, 2001
Jacob's LadderMiscJan 26, 2001
Automatic Plant Irrigation System Circuit for Watering Plants without any Human Interference.MiscDec 07, 2014
Circuit for gold wafer cardMiscFeb 21, 2005
Nokia 3310 Lcd Thermometer using DS18B20MiscFeb 21, 2005
Lost keys finder using HCF4069MiscFeb 21, 2005
Lightning DetectorMiscFeb 21, 2005
Geomagnetic field detectorMiscFeb 21, 2005
Fogger smoke machine controllerMiscJan 26, 2001
Pulse Induction Metal Detector part 1 (PDF)MiscJun 27, 2010
Pulse Induction Metal Detector part 2 (PDF)MiscJun 27, 2010
Mobile APRS / GPS tracking systemMiscMay 01, 2004
GPS receiver support kitMiscMay 01, 2004
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
Lightning detector circuit diagramMiscSep 08, 2009
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
6 Pole ElectroMagnet Motor (aka Simple Brushless motor)Misc 
Solid State Tesla Coil and Wireless PowerMisc 
Tesla coil construction projectMisc 
Vareity of circuits for interfacing to/from TTL logicMisc 
Dinsmore 1490 digital compassMiscNov 29, 2002
Geiger counter circuit diagramMiscNov 29, 2002
Electric field disturbance monitorMiscJan 26, 2001
Inexpensive seismometer projectMiscDec 15, 2002
Aurora Alarm: Automated Detection System for the Northern LightsMisc 
Digg Button KitMiscOct 12, 2009
SIM card reader circuit diagramMiscOct 12, 2009
Circuit for driving a liquid crystal (LCD) shutter to simply pass or block lightMiscDec 21, 2009
Lie detectorMisc 
Simple metal detector based on a PIC12F683 microcontrollerMiscJun 27, 2010
Three component bat detector based on a PIC12F683 microcontrollerMiscJun 27, 2010
Homemade GPS jammer using a MC145151 frequency synthesizerMiscJan 17, 2011
2D3 Nixie clock schematic using Atmel microcontrollerMiscSep 13, 2006
Popular Electronics Ultrasound DetectorMiscJan 01, 2003
Navigator 555A radio direction finder (RDF) circuit diagramMiscMay 01, 2004
Touch switchesMiscMar 05, 2009
Build your own UFO Bino-Scope unit - upgrade binoculars to become a photosensitive bino-scopeMisc 
Color sensor circuitMisc 
PASCO scientific model SF-9211 stroboscope schematic (PDF)Misc 
CMOS Logic ExperimentsMisc 
Miscellaneous Circuits for Idea PurposesMisc 
u-Blox GPS receiver boardMiscMar 23, 2003
Assorted digital circuitsMiscMar 18, 2003
Basic opamp circuitsMiscMar 18, 2003
Miscellaneous simple circuitsMiscMar 18, 2003
Simple electronic keyerMisc 
FM Morse Code KeyerMisc 
Easy Morse Code Keyer CircuitMisc 
CW Tone KeyerMisc 
Digital Call Sign AnnunciatorMiscJun 09, 2002
Monitor output from Motorola Oncore GPS engine in HP Z3801A in GPS Disciplined OscillatorMiscMay 01, 2004
Ultrasonic switch transmitter and receiver circuit diagramMiscJan 26, 2001
Plant Watering Watcher (moisture meter)Misc 
A small collection of quick to build electronic circuit designsMisc 
DIY Plasma Globe using an automotive ignition coilMisc 
DIY Tesla coil - DC Powered with Plasma OutputMisc 
StroboscopeMiscAug 17, 2009
Very basic circuitsMiscJan 26, 2001
Bat detectorMiscJan 26, 2001
Electronic canary doorbellMisc 
Electronic dazerMisc 
Jacob's LadderMisc 
Negative Ion DetectorMisc 
Negative Ion GeneratorMisc 
Tesla coilMisc 
Solid state tesla coilMisc 
High voltage zappersMisc 
Morse Code Practice Keyer 1MiscJan 26, 2001
Morse Code Practice Keyer 2MiscJan 26, 2001
741 Light SensorMiscJan 26, 2001
Fluid level detectorMiscJan 26, 2001
Touch switch using transistorsMisc 
FCTS ProjectMiscMar 25, 2001
Count Accumulator for Radiation Levels (CARL)MiscSep 21, 2006
Modifications for CDV700 Geiger CounterMiscSep 21, 2006
The WB0RIO 6U8A Code Practice OscillatorMiscMay 19, 2015
Big Ear Stereo Parabolic MicrophoneMiscSep 21, 2006
Ultra Low Power LCD IndicatorMiscSep 21, 2006
Vacuum Tube B+ Delay CircuitMiscMay 19, 2015
12 Volt Toilet Tank Refiller circuit diagramMiscSep 21, 2006
Morse Code Beacon KeyerMiscJan 26, 2001
Weather station with pressure reading, relative humidity, indoor & remote temperature readingMisc 
Induction receiver for tracing wiring behind walls, hearing lightning and other electric dischargesMisc 
Texas Instruments collection of differential op-amp circuits (PDF)Misc 
Texas Instruments collection of buffer op-amp circuits for ADCMisc 
Building a Hardware Random Bit GeneratorMisc 
Delayed shutter control for Kodak DC-20MiscJul 24, 2002
Morse code displayMiscJul 24, 2002
Circuit for temperature stabilization of a MTP3055E MOSFETMiscSep 01, 2009
Kenwood TH-D7 NMEA GPS bug fixMisc 
Doorbell for the deaf that provides a delayed visual indication when a doorbell switch is pressedMiscNov 27, 2002
Electromagnetic field detectorMiscJan 26, 2001
Insect Repellant (22KHz audio oscillator)MiscNov 27, 2002
High Quality IntercomMiscNov 27, 2002
Magnetic Gun.MiscNov 27, 2002
Single chip metal detecor with a range of a few inches based on CS209AMisc 
Static Electricity / Negative Ion DetectorMiscNov 27, 2002
Ultrasonic dog whistleMiscJan 26, 2001
Scaling ADXL50 accelerometer outputMiscJan 26, 2001