The circuit sits with the true led illuminated

increases. Separate the two touch pads and attach them to the back of each hand. As the subject feels nervous, he will sweat and change the frequency of the circuit. The photos show the circuit built on PC boards with separate touch pads.

LIE DETECTOR-1
This circuit detects the resistance between your
fingers to produce an oscillation. The detection-
points will detect resistances as high as 300k and
as the resistance decreases, the frequency

LIE DETECTOR-3
This circuit detects the
resistance between your
fingers to turn the 4 LEDs. As
you press harder, more LEDs
are illuminated.

To turn the circuit OFF, a finger on the OFF pads will activate the first transistor and this will rob the "super transistor" of voltage and the circuit will turn OFF.

This project is available as a from Talking Electronics for $6.00 plus $4.00