There are 222 circuit schematics available in this category. Click here for all circuit diagrams. Last circuit added on Thursday, 30 July 2015.

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CircuitCategoryDate AddedOK?Votes 
Simple moisture indicatorMisc 0
Two-tone doorbell using 555 timerMisc 0
omentary High Voltage Arc Circuit - can be used to Ignite a barbeque or a Gas in a Potato GunMisc 0
Simple BFO metal detector using 2N3906 and 2N3904 transistorsMiscMay 30, 20072
Cat or Dog Detector - can be used to control entry on a Cat or Dog DoorMisc 0
Fish caller circuitMiscSep 23, 20090
Powerful stun gun / taser circuit diagramMiscSep 23, 2009-1
Ultrasonic sound detector / snifferMiscSep 23, 20090
Air flow detectorMisc 0
Simple Frequency Reader for conversion VFOsMiscOct 05, 20090
Eddie's Composting Loo fan controllerMiscMar 09, 20120
Touch operated Band switch for Radio SetMiscOct 25, 20140
Digital Remote ThermometerMiscJun 26, 20090
Capacitive SensorMiscJun 26, 20091
Mains Remote-Alert - Remotely operates beeper and/or a LED via mains supply lineMiscJun 26, 20090
Touch activated switch using CD4011 CMOS NAND gateMiscJun 26, 20090
Voice activated switch (VOX) circuit diagramMiscJun 26, 20090
UltraSonic RadarMiscJun 26, 20090
Nocturnal Animals WhiskerMisc 0
Insect RepellantMiscSep 17, 2009-2
Digital Radar SpeedometerMiscOct 21, 20090
Electromagnetic Field Probe with Meter Output using an LF351 opampMiscOct 19, 20090
Beat Balance Metal DetectorMisc 0
Coil Coupled Operation Metal DetectorMiscNov 10, 20090
Missing Pulse Detector Circuit with 555 ICMiscOct 03, 20130
Chaos generatorMiscJan 26, 20010
A Two-Way Morse Practice SetMisc 0
Voltage Comparator Information And CircuitsMiscApr 27, 20030
Visible and Infrared Light DetectorsMisc 0
Light Activated Detector Circuit (LM393/LM555)MiscSep 10, 20060
10 GHz CW Radar based on a X-band GunnplexerMisc 0
GoldPic 3 Pulse Induction Metal Detector (has electronic kit available)MiscMay 30, 20070
Photodiode primer and interface circuit diagrams including photovoltaic and photoconductive modesMiscMar 04, 20100
Full-duplex doorphone with 3 wires connectionMiscMar 23, 20030
G Strain energy absorberMiscJan 01, 20030
Amateur weather station to APRS interface ALWXI-01MiscOct 07, 20090
Switch debouncer circuits including transistor, CMOS logic and a 555 timer based designMiscJan 31, 20100
Interesesting circuits using diodes ideal for education or introductory courses on electronicsMiscFeb 20, 20100
Selection of run circuits to experiment with the 4017 CMOS decade counter chipMiscFeb 26, 20100
Variety of applications using a CMOS 4001 2-input NOR gate including a PCB layoutMiscFeb 20, 20100
Select of interesting electronic circuits that require only a single transistor ideal for educationMiscFeb 20, 20100
Small selection of useful circuitsMiscFeb 09, 20100
Marshmallow Bazooka with a PIC12F615 based capacitor discharge ignition systemMiscMay 16, 20100
Touch sensistive touchpad based on a PIC16F627A microMiscMay 24, 20100
Electric cockroach zapperMiscMay 24, 20100
Home-Built Magnetic LevitatorMisc 0
Project for experimenting with magnetic levitationMisc 0
FET based metal detector using MPF102 / J310 BF998 FETsMiscMay 30, 20070
Ultrasound detectorMiscSep 13, 20060
Build Your Own Video-Rate 2-photon MicroscopeMiscSep 25, 20090
Sony RS-422 ADAT sync cable pinoutMiscSep 10, 20060
Garmin Foretrex 101,201, Forerunner 101,201 to Serial DB9 cable schematic pinoutMiscSep 10, 20060
Simple DTMF Repeater Controller using PIC16F84Misc 0
Build a Simple Bat DetectorMiscJan 08, 20140
Capacitance to Voltage conversionMisc 0
Biasing Op-Amps into Class AMiscJan 01, 20030
Bleeper box for time referenceMiscMay 01, 20040
Random noise generatorMiscJan 26, 20010
Analog pulse counterMiscAug 12, 20010
Analog opto-isolatorMiscAug 12, 20010
Pulse width modulators (PWM)MiscAug 12, 20010
Pulse width to voltage converterMiscAug 12, 20010
Air flow detector using an incandescent lamp to detect airflowMisc 0
Simple Lie DetectorMiscSep 01, 20090
Low Voltage AlarmMiscSep 01, 20090
Rain DetectorMiscSep 01, 20090
Magnetic levitation deviceMiscAug 14, 20020
Tesla power receiverMiscJan 06, 20020
1.9 Kilojoule Coil GunMiscNov 16, 20100
A spark throwing tesla coil made entirely of garbageMiscNov 16, 20100
Basic Homebuilt Discrete DTL gate circuits (Diode Transistor Logic)Misc 0
Lazer Tag Equipment ModificationsMiscMar 23, 20030
Inexpensive APRS Weather StationMiscAug 14, 20020
Two-component metal detector using a 4093Misc 0
Induced voltage sensor delta-peak trigger for coilgunMisc 0
Open loop pulse trigger module for coilgunMisc 0
Optical speed trap to measure the the velocity of the projectileMisc 0
Optical trigger module for coilgunMisc -1
Power MOSFET module for coilgunMisc 0
Three stage induced voltage triggered coilgunMisc 0
Thyristor fired coilgun circuit diagramMisc 0
Magnetic levitation project from Electronics Now, February 1996Misc 0
LNS Technologies Levitator Kit circuit diagramMisc 0
Magnetic levitation project from Popular Electronics, May 1966Misc 0
Magnetic levitation project from Popular Electronics, May 1989Misc 0
Barry's magnetic levitation projectMisc 0
Barry's Coilgun Mark I circuit diagramsMisc 0
Barry's Coilgun Mark II circuit diagransMisc 0
Barry's Coilgun Mark III circuit diagransMisc 0
Barry's Coilgun Mark IV circuit diagransMisc 0
Circuit diagram for Coilgun Pistol Pskov 1100Misc 0
1uS light pulse descriminator plus F to V converter (PDF)MiscJan 26, 20010
Broadband 2MHz optical fiber receiver (PDF)MiscJan 26, 20010
Modulated light receiver circuit (PDF)MiscJan 26, 20010
1uS light pulse receiver plus post amp (MISC)MiscJan 26, 20010
Broadband 5MHz optical fiber receiver (PDF)MiscJan 26, 20010
High-speed 75MHz light receiver (PDF)MiscJan 26, 20010
Basement doorbell beeper (PDF)MiscJan 26, 20010
Time to dust indicator - battery powered dust indicator (PDF)MiscJan 26, 20010
Low-power optical interrupter (PDF)MiscJan 26, 20010
Simple nitrogen spark generator (PDF)MiscJan 26, 20010
Simple DIY BFO metal detectorMiscJun 27, 20100
Op Amp Comparator with Hysteresis with SPICE simulationMiscMar 26, 20110
Op Amp Precision Half-wave Rectifier including SPICE simulationMiscMar 26, 20110
Single-Supply AC Inverting Op Amp amplifier with SPICE simulationMiscMar 26, 20110
Hacking the Hot Wheels Radar Gun - includes circuit of analog front endMisc 0
Ultrasonic transducer oscillator circuitMiscJan 26, 20010
Build logic gates using discrete partsMiscJan 26, 20010
Jacob's LadderMiscJan 26, 20010
Automatic Plant Irrigation System Circuit for Watering Plants without any Human Interference.MiscDec 07, 20140
Circuit for gold wafer cardMiscFeb 21, 20050
Nokia 3310 Lcd Thermometer using DS18B20MiscFeb 21, 20050
Lost keys finder using HCF4069MiscFeb 21, 20050
Lightning DetectorMiscFeb 21, 20050
Geomagnetic field detectorMiscFeb 21, 20050
Fogger smoke machine controllerMiscJan 26, 20010
Pulse Induction Metal Detector part 1 (PDF)MiscJun 27, 20100
Pulse Induction Metal Detector part 2 (PDF)MiscJun 27, 20100
Mobile APRS / GPS tracking systemMiscMay 01, 20040
GPS receiver support kitMiscMay 01, 20040
Dekatron circuit diagram - device used for dividing by 10 during the valve eraMiscOct 25, 20090
Circuit diagrams for making logic gates from discrete componentsMiscOct 25, 20090
Lightning detector circuit diagramMiscSep 08, 20090
Heathkit Groundtrack GR-1290 VLF metal detector circuit diagram and detector coil construction notesMiscJun 27, 20100
White's Surfmaster PI (pulse induction) metal detector schematic diagramMiscJun 27, 20100
6 Pole ElectroMagnet Motor (aka Simple Brushless motor)Misc 0
Solid State Tesla Coil and Wireless PowerMisc 0
Tesla coil construction projectMisc 0
Vareity of circuits for interfacing to/from TTL logicMisc 0
Dinsmore 1490 digital compassMiscNov 29, 20020
Geiger counter circuit diagramMiscNov 29, 20020
Electric field disturbance monitorMiscJan 26, 20010
Inexpensive seismometer projectMiscDec 15, 20020
Aurora Alarm: Automated Detection System for the Northern LightsMisc 0
Digg Button KitMiscOct 12, 20090
SIM card reader circuit diagramMiscOct 12, 20090
Circuit for driving a liquid crystal (LCD) shutter to simply pass or block lightMiscDec 21, 20090
Lie detectorMisc 0
Simple metal detector based on a PIC12F683 microcontrollerMiscJun 27, 20100
Three component bat detector based on a PIC12F683 microcontrollerMiscJun 27, 20100
Homemade GPS jammer using a MC145151 frequency synthesizerMiscJan 17, 20110
2D3 Nixie clock schematic using Atmel microcontrollerMiscSep 13, 20060
Popular Electronics Ultrasound DetectorMiscJan 01, 20030
Navigator 555A radio direction finder (RDF) circuit diagramMiscMay 01, 20040
Touch switchesMiscMar 05, 20090
Build your own UFO Bino-Scope unit - upgrade binoculars to become a photosensitive bino-scopeMisc 0
Color sensor circuitMisc 0
PASCO scientific model SF-9211 stroboscope schematic (PDF)Misc 0
u-Blox GPS receiver boardMiscMar 23, 20030
Assorted digital circuitsMiscMar 18, 20030
Basic opamp circuitsMiscMar 18, 20030
Miscellaneous simple circuitsMiscMar 18, 20030
Simple electronic keyerMisc 0
FM Morse Code KeyerMisc 0
Easy Morse Code Keyer CircuitMisc 0
CW Tone KeyerMisc 0
Digital Call Sign AnnunciatorMiscJun 09, 20020
Monitor output from Motorola Oncore GPS engine in HP Z3801A in GPS Disciplined OscillatorMiscMay 01, 20040
Ultrasonic switch transmitter and receiver circuit diagramMiscJan 26, 20010
Plant Watering Watcher (moisture meter)Misc 0
A small collection of quick to build electronic circuit designsMisc 0
DIY Plasma Globe using an automotive ignition coilMisc 0
DIY Tesla coil - DC Powered with Plasma OutputMisc 0
StroboscopeMiscAug 17, 20090
Very basic circuitsMiscJan 26, 20010
Bat detectorMiscJan 26, 20010
Electronic canary doorbellMisc 0
Electronic dazerMisc 0
Jacob's LadderMisc 0
Negative Ion DetectorMisc 0
Negative Ion GeneratorMisc 0
Tesla coilMisc 0
Solid state tesla coilMisc 0
High voltage zappersMisc 0
Morse Code Practice Keyer 1MiscJan 26, 20010
Morse Code Practice Keyer 2MiscJan 26, 20010
741 Light SensorMiscJan 26, 20010
Fluid level detectorMiscJan 26, 20010
Touch switch using transistorsMisc 0
FCTS ProjectMiscMar 25, 20010
Count Accumulator for Radiation Levels (CARL)MiscSep 21, 20060
Modifications for CDV700 Geiger CounterMiscSep 21, 20060
The WB0RIO 6U8A Code Practice OscillatorMiscMay 19, 20150
Big Ear Stereo Parabolic MicrophoneMiscSep 21, 20060
Ultra Low Power LCD IndicatorMiscSep 21, 20060
Vacuum Tube B+ Delay CircuitMiscMay 19, 20150
12 Volt Toilet Tank Refiller circuit diagramMiscSep 21, 20060
Morse Code Beacon KeyerMiscJan 26, 20010
Weather station with pressure reading, relative humidity, indoor & remote temperature readingMisc 0
Induction receiver for tracing wiring behind walls, hearing lightning and other electric dischargesMisc 0
Texas Instruments collection of differential op-amp circuits (PDF)Misc 0
Texas Instruments collection of buffer op-amp circuits for ADCMisc 0
Building a Hardware Random Bit GeneratorMisc 0
Delayed shutter control for Kodak DC-20MiscJul 24, 20020
Morse code displayMiscJul 24, 20020
Circuit for temperature stabilization of a MTP3055E MOSFETMiscSep 01, 20090
Kenwood TH-D7 NMEA GPS bug fixMisc 0
Doorbell for the deaf that provides a delayed visual indication when a doorbell switch is pressedMiscNov 27, 20020
Electromagnetic field detectorMiscJan 26, 20010
Insect Repellant (22KHz audio oscillator)MiscNov 27, 20020
High Quality IntercomMiscNov 27, 20020
Magnetic Gun.MiscNov 27, 20020
Single chip metal detecor with a range of a few inches based on CS209AMisc 0
Static Electricity / Negative Ion DetectorMiscNov 27, 20020
Ultrasonic dog whistleMiscJan 26, 20010
Scaling ADXL50 accelerometer outputMiscJan 26, 20010
Infrasound circuits including several infrasound amplifier circuit diagramsMiscJul 05, 20150
Ghost detector - detects if a ghost disturbs the electric field in the vicinity of the deviceMiscJul 10, 20150
Lightning detector to receive static pulses from lightning at a frequency near 200 kHzMiscJul 10, 20150
Atmospheric receiver to detect crackling static in a radio produced by lightningMiscJul 10, 20150
Powerful buzzer for use as a doorbell or to notify others in different rooms dinner is ready etcMiscJul 15, 20150
Powerful Security Siren - Transistors based and operates from 12V power supplyMiscJul 15, 20150
Whistle Responder - Beeps when hears your whistle, A gadget suitable for key-holders, games etc.MiscJul 22, 20150
Water Level Indicator Using 7-Segment DisplayMiscJul 30, 20150
Rainwater Storage GaugeMiscJul 30, 20150
Cat and Dog RepellerMiscJul 30, 20150
Inexpensive Remote Watering SystemMiscJul 30, 20150
You Have Mail! Letterbox monitoring systemMiscJul 30, 20150
Environmentally-friendly Mosquito RepellerMiscJul 30, 20150
Doorbell Memory Circuit DiagramMiscJul 30, 20150
Plant Watering Watcher Circuit SchematicMiscJul 30, 20150
Salt Taster Circuit DiagramMiscJul 30, 20150