There are 177 circuit schematics available in this category. Click here for all circuit diagrams. The Last circuit was added on Sunday, 24 July 2016.Please note some adblockers will suppress the schematics as well as the advertisement so please disable if the schematic list is empty.

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CircuitCategoryDate AddedOK?Votes 
RCM710 electronic scale, technical manual including schematicTestApr 12, 2001Status-1 vote up vote down
Ground Fault IndicatorTest Status0 vote up vote down
Sound pressure level meterTestSep 23, 2009Status1 vote up vote down
True RMS Watt MeterTestSep 23, 2009Status1 vote up vote down
The u-counter, a PIC based programmable frequency meter (PDF)TestOct 05, 2009Status0 vote up vote down
Ultra-simple Voltage ProbeTestJun 26, 2009Status0 vote up vote down
Wire tracerTest Status-1 vote up vote down
IR Remote Control TesterTestJul 05, 2012Status-1 vote up vote down
Digital Voltmeter using ICL7107TestSep 17, 2009Status0 vote up vote down
Beeper to find short circuitsTestOct 19, 2009Status1 vote up vote down
Led display digital Voltmeter using ICL7107TestSep 17, 2009Status1 vote up vote down
MOSFET transistor testerTestNov 05, 2009Status1 vote up vote down
Oscilloscope testing module (huntron circuit)TestNov 10, 2009Status0 vote up vote down
Logic probeTestOct 19, 2009Status-1 vote up vote down
Pulse Reading Logic ProbeTestOct 19, 2009Status1 vote up vote down
Stereo Test Tone GeneratorTestOct 21, 2009Status0 vote up vote down
Continuity Tester based on 4 x 2N3904 and 1 x 2N3905 transistorsTestOct 19, 2009Status1 vote up vote down
Audible Logic Probe based on LM339 operational amplifierTestOct 19, 2009Status0 vote up vote down
Single chip digital voltmeter using ICL7129TestNov 05, 2009Status0 vote up vote down
Latching Continuity Tester to help find intermittent faults, has quite a few innovative featuresTestOct 19, 2009Status1 vote up vote down
Linear Resistance MeterTestOct 19, 2009Status-1 vote up vote down
XTal Tester for testing quartz crystals based on a pair of BC550C PNP transistorsTestOct 19, 2009Status-1 vote up vote down
Self-powered Fast Battery-Tester - Tests 1.5 to 15 Volt cellsTestSep 17, 2009Status1 vote up vote down
Microphone polarity tester circuit diagranTestApr 14, 2010Status-1 vote up vote down
Low-Drift High-Impedance JFET DC VoltmeterTestJan 08, 2014Status0 vote up vote down
Resistor decade boxTestAug 14, 2002Status0 vote up vote down
Simple test equipment to buildTest Status-1 vote up vote down
RF Power Meter for the QRP measures up to 25 wattsTest Status2 vote up vote down
Dip Oscillator for HFTest Status0 vote up vote down
High Impedance VoltmeterTestSep 10, 2006Status1 vote up vote down
Servo Motor Test Circuit (LM555)Test Status0 vote up vote down
Frequency counter based on PIC16F628 and LCD displayTestJun 19, 2011Status-1 vote up vote down
220V live wire-in-wall scannerTestMar 23, 2003Status0 vote up vote down
Test oscillator that generates sinewaves, squarewaves, and triangle wavesTestFeb 20, 2013Status-1 vote up vote down
PPMScope DIY oscilloscope with 1MHz sampling rate and Windows softwareTestFeb 20, 2013Status1 vote up vote down
KD1JV Digital SWR / Power MeterTestApr 12, 2014Status1 vote up vote down
Low Power Antenna Analyzer and ATU Tuning AidTest Status0 vote up vote down
Fixed Frequency "Tuner Dipper"Test Status0 vote up vote down
Universal frequency counter & voltage meterTestOct 07, 2009Status1 vote up vote down
ESR MeterTestMay 17, 2002Status-2 vote up vote down
Line Output / Flyback transformer testerTestMay 17, 2002Status0 vote up vote down
PCB board tester and RF detector circuir diagramsTestFeb 09, 2010Status0 vote up vote down
Alarm circuit to remind you to turn off your DMM (digital multimeter)TestJan 31, 2010Status-1 vote up vote down
Function generator based on 555 timer and three 2N2222 transistorsTestFeb 05, 2010Status-1 vote up vote down
Multi-trace scope display that allows up to 4 channels to be viewed on a single oscilloscope channelTestFeb 26, 2010Status-1 vote up vote down
DDS from 1-60 MHz with built-in amplifier and variable output level using Analog Devices AD9851Test Status0 vote up vote down
Isolated oscilloscope probeTestMay 16, 2010Status0 vote up vote down
Superprobe handheld test device based on a PIC16F870TestMay 24, 2010Status1 vote up vote down
Build an inexpensive Hall effect GaussmeterTest Status0 vote up vote down
Design for a slightly more expensive GaussmeterTest Status0 vote up vote down
VCR head amplifier testerTestMay 25, 2012Status0 vote up vote down
Conrad Electronics MM3610D multimeter cable pinoutTestSep 10, 2006Status-1 vote up vote down
Audio MillivoltmeterTestApr 14, 2010Status0 vote up vote down
Microphone Circuit Test OscillatorTestApr 14, 2010Status1 vote up vote down
Distortion analyser circuit diagramTestApr 14, 2010Status0 vote up vote down
The ESP SIM (Sound Impairment Monitor)TestApr 14, 2010Status0 vote up vote down
Linkwitz Cosine Burst GeneratorTestApr 14, 2010Status0 vote up vote down
Amplified field strength meter / RF snifferTestApr 14, 2011Status1 vote up vote down
3 in one tester (audio, tone generator, diode/circuit tester)Test Status-1 vote up vote down
In-circuit electrolytic capacitor checkerTestMar 27, 2009Status0 vote up vote down
Logic probe with pulserTestMar 27, 2009Status-1 vote up vote down
Electric field & leakage detectorTestAug 12, 2001Status0 vote up vote down
Simple Polarity TesterTestSep 01, 2009Status0 vote up vote down
20kV Digital High Voltage MeterTestNov 16, 2010Status1 vote up vote down
Eight simple power supplies for your workbench (mainly vacuum tube based)TestApr 10, 2014Status0 vote up vote down
Filter Choke AnalyzerTestApr 10, 2014Status0 vote up vote down
Vacuum Tube Grid Leak Detector: Needs an AmplifierTestApr 10, 2014Status0 vote up vote down
A Load Box for testing power suppliesTestApr 10, 2014Status0 vote up vote down
Low resistance adapter for a DMM (digital multimeter)TestApr 10, 2014Status0 vote up vote down
Vacuum Tube Plate Detector: Needs an AmplifierTestApr 10, 2014Status0 vote up vote down
Miniature SWR / RF power meter circuitTestFeb 15, 2014Status-1 vote up vote down
Schematics and C code for a PIC frequency counter operating up to about 50 MHz (7 segment)Test Status0 vote up vote down
Schematics and C code for a 0-5V PIC LCD volt meterTest Status1 vote up vote down
Schematics and C code for a PIC frequency counter operating up to about 50 MHz (LCD)Test Status0 vote up vote down
Not So Tiny Power Meter - Measures power consumption for entire apartment Not So Tiny Power MeterTestFeb 21, 2013Status-1 vote up vote down
LED based transistor tester LED based transistor testerTestOct 05, 2012Status1 vote up vote down
TTL pulse counter/logic probeTest Status0 vote up vote down
Quickie servo tester for testing servo motors (based on Atmel AT90S2343)TestAug 17, 2009Status-1 vote up vote down
Frequency and capacitance meterTestJan 26, 2001Status0 vote up vote down
Transistor TesterTestNov 13, 2010Status1 vote up vote down
Wire Tracer (Receiver)TestNov 13, 2010Status-1 vote up vote down
Wire Tracer (Transmitter)TestNov 13, 2010Status0 vote up vote down
Elecraft XG2 receiver test oscillator (PDF)TestSep 13, 2006Status0 vote up vote down
Contactless Mains Voltage IndicatorTest Status0 vote up vote down
Mini tester: Handles continuity testing, resistor testing, capacitor testing and diode testingTest Status1 vote up vote down
Precision audio millivoltmeterTestFeb 21, 2005Status0 vote up vote down
PIC16F84 based diode testerTestFeb 21, 2005Status-1 vote up vote down
Continuity tester using transistorsTestFeb 21, 2005Status0 vote up vote down
Latching continuity tester using 4093TestFeb 21, 2005Status0 vote up vote down
Linear Resistance MeterTestFeb 21, 2005Status0 vote up vote down
Crystal tester circuit diagramTestFeb 21, 2005Status0 vote up vote down
Capacitance meterTestFeb 21, 2005Status0 vote up vote down
Digital voltmeter (DVM)TestFeb 21, 2005Status0 vote up vote down
Transistor tester using 555 timer and 4027TestFeb 21, 2005Status-1 vote up vote down
Function generator based upon 8038 waveform generator ICTestFeb 21, 2005Status0 vote up vote down
Picoammeter circuit schematic with 4 ranges using CA3420TestFeb 21, 2005Status0 vote up vote down
Beeper to find short circuits (continuity tester)TestFeb 21, 2005Status2 vote up vote down
MOSFET tester for N-type MOSFET transistorsTestFeb 21, 2005Status0 vote up vote down
Inductive meter adapter to measure inductance using a frequency counterTestFeb 21, 2005Status0 vote up vote down
Crystal tester that covers a range of 32kHz to 24MHzTestFeb 21, 2005Status-1 vote up vote down
Oscilloscope testing module (Huntron circuit) that shows Lissajous patternsTestFeb 21, 2005Status0 vote up vote down
Logic probe with 7-segment display based on 74LS00 and 74LS47TestFeb 21, 2005Status0 vote up vote down
Simple light sensor adapter for oscilloscopeTestJan 26, 2001Status0 vote up vote down
TDR cable reflection tester (Time Domain Reflectometer)TestSep 21, 2006Status1 vote up vote down
Soft Power On Tester for AmplifiersTestJan 29, 2010Status0 vote up vote down
TXTVb - 70cm ATV Test Generator (PDF)Test Status0 vote up vote down
BCD readout frequency counterTestAug 18, 2009Status0 vote up vote down
LCD Frequency CounterTestAug 18, 2009Status1 vote up vote down
Miniscope - simple all-valve 1-inch CRT oscilloscopeTestOct 25, 2009Status1 vote up vote down
Panel Mounting Radio Frequency CounterTestAug 18, 2009Status0 vote up vote down
Simple Frequency CounterTestAug 18, 2009Status0 vote up vote down
Heathkit signal generator user manual and circuit diagramTestOct 25, 2009Status0 vote up vote down
Spectrum analyzer Mk 1TestAug 18, 2009Status0 vote up vote down
Spectrum analyzer Mk 2TestAug 18, 2009Status0 vote up vote down
TinyScope - simple all-valve 1-inch CRT oscilloscopeTestOct 25, 2009Status0 vote up vote down
Z80 controlled Viscometer projectTestAug 18, 2009Status0 vote up vote down
Field Strength Meter (FSM) covers 2Mhz - 1Ghz with peak reception at 3-200MhzTest Status0 vote up vote down
UHF signal generatorTest Status0 vote up vote down
VHF signal generatorTest Status0 vote up vote down
-20 dB Couplers for use with a with a spectrum analyzer or other sensitive detectorTest Status0 vote up vote down
-20 dBm, 14.060 MHz Precision Signal SourceTest Status0 vote up vote down
Precision VXO for Crystal Characterization & MatchingTest Status0 vote up vote down
Return Loss BridgeTest Status0 vote up vote down
Mini oscilloscope based on PIC18F4620 and standard 16x2 text LCD display moduleTestJun 27, 2010Status0 vote up vote down
AD9850 DDS daughterboardTestSep 21, 2006Status0 vote up vote down
Signal Tracer and InjectorTestSep 13, 2006Status-1 vote up vote down
TDS/PPM Meter for measuring of the amount of salts in a solutionTestMar 29, 2009Status0 vote up vote down
Homebrew signal generator tunable from 3 to 30 MhzTestOct 08, 2009Status0 vote up vote down
Precision Frequency MarkerTest Status0 vote up vote down
Simple Inductance MeterTest Status0 vote up vote down
VCR Tuner Based RF Spectrum Analyzer SchematicTestSep 21, 2006Status0 vote up vote down
LCD frequency counter (PIC16F84)TestNov 29, 2002Status0 vote up vote down
Simple electronic S meterTest Status0 vote up vote down
Standalone LED testerTestNov 02, 2010Status0 vote up vote down
Fluke 8010 / 8012 InterfaceTestSep 25, 2009Status0 vote up vote down
UTP Cable TesterTestSep 25, 2009Status0 vote up vote down
10Hz - 100KHz D.D.S. Function GeneratorTestSep 21, 2006Status0 vote up vote down
555 Timer IC Tester circuit diagramTestJan 26, 2001Status1 vote up vote down
555 go / no-go tester circuit diagramTestJan 08, 2002Status0 vote up vote down
Battery Tester for 1.5 and 9VTest Status0 vote up vote down
Continuity tester V2 circuit diagramTestJan 26, 2001Status1 vote up vote down
Continuity tester circuit diagramTestJan 26, 2001Status-1 vote up vote down
Logic probeTestJan 26, 2001Status0 vote up vote down
Simple pH Meter Circuit, A Low Cost Adapter for Your Digital VoltmeterTestNov 02, 2010Status0 vote up vote down
Magic Eye Tube WavemeterTestMay 19, 2015Status0 vote up vote down
TTL Pulse Reading Logic ProbeTestSep 21, 2006Status0 vote up vote down
Stereo Test Tone GeneratorTestSep 21, 2006Status0 vote up vote down
Octopus Curve TracerTestMay 19, 2015Status0 vote up vote down
Pulse Reading Logic ProbeTestJan 26, 2001Status0 vote up vote down
LC meter with LCD display for readoutTest Status0 vote up vote down
An ESR Meter For Electrolytic Capacitors (and Low Ohms Meter)TestJun 24, 2015Status-1 vote up vote down
Build your own Q Meter projectTestJun 24, 2015Status0 vote up vote down
A Simple RF Probe For Your DVMTestJun 24, 2015Status1 vote up vote down
An RF Voltmeter for Transceiver ServicingTestJun 24, 2015Status0 vote up vote down
Medium and Very High Quality Two Tone Generators for Transceiver TestingTestJun 24, 2015Status0 vote up vote down
Highly sensitive and selective Field Strength Meter systemTestApr 14, 2011Status0 vote up vote down
Wide dynamic range Field Strength Meter mark ITestApr 14, 2011Status0 vote up vote down
Wide dynamic range Field Strength Meter mark IITestApr 14, 2011Status0 vote up vote down
Digital Wattmeter, measures from nanowatts to kilowatts using AD8307, PIC16F876, LCD DisplayTest Status0 vote up vote down
SWR Bridge 1 to 1000 Mhz (1GHz)Test Status0 vote up vote down
Field strength meter for the 137 kHz bandTestMay 01, 2004Status0 vote up vote down
Multi wire cable tester that handles up to eight conductorsTestNov 27, 2002Status0 vote up vote down
Connection tester for checking solder joints and other connectionsTestNov 27, 2002Status0 vote up vote down
EMF field probe (electromagnetic field probe) covering up to 100kHzTestJan 26, 2001Status0 vote up vote down
Function generator based on 8038PCD function generator ICTestJan 26, 2001Status0 vote up vote down
Zener diode tester based on a 555 timerTestJan 26, 2001Status0 vote up vote down
Accurate Digital LC Meter based on a PIC16F84TestFeb 20, 2013Status0 vote up vote down
Pulse Generator And Signal Tracer Circuit DiagramTestJul 22, 2015Status1 vote up vote down
The Curious C-Beeper - a probe beeps at a frequency that varies with capacitanceTestSep 03, 2015Status1 vote up vote down
DIY Digital AC Watt MeterTestSep 30, 2015Status1 vote up vote down
Relative Field Strength Meter For A DMMTestOct 06, 2015Status0 vote up vote down
Logic Probe With SoundTestOct 06, 2015Status0 vote up vote down
DIY 4-Digit LED Digital Voltmeter Module based on ATmega8TestJul 03, 2016Status1 vote up vote down
RF Power CalibratorTestJul 24, 2016Status0 vote up vote down
TDR Test System - WA0PIATestJul 24, 2016Status1 vote up vote down
Satellite FinderTestJul 24, 2016Status-1 vote up vote down
Simple Crystal Tester - F5JTZTestJul 24, 2016Status0 vote up vote down