Simple Lie Detector
Electronic Schematics > Miscellaneous > Simple Lie Detector

Here's a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring skin resistance, which goes down when you lie.

This is the schematic of the Lie Detector


Part Total Qty. Description Substitutions
R1 1 33K 1/4W Resistor  
R2 1 5K Pot  
R3 1 1.5K 1/4W Resistor  
C1 1 1uF 16V Electrolytic Capacitor  
Q1 1 2N3565 NPN Transistor  
M1 1 0-1 mA Analog Meter  
MISC 1 Case, Wire, Electrodes (See Nots)  


1. The electrodes can be alligator clips (although they can be painful), electrode pads (like the type they use in the hospital), or just wires and tape.

2. To use the circuit, attach the electrodes to the back of the subjects hand, about 1 inch apart. Then, adjust the meter for a reading of 0. Ask the questions. You know the subject is lying when the meter changes.

Title: Simple Lie Detector
electronic circuit
Published on: 2005-02-10
Reads: 1406
Print version: Print version

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