Make your own real-working lie detector. Provide yourself or others a great learning experience with a kit ideal for beginners or experimenters. This kit provides you with the essential elements needed to build this simple lie detector. It contains a 82KΩ resistor, 4.7KΩ resistor, 3906 transistor, 3904 transistor, and a .01 mfd ceramic disk capacitor.It also contains a paper circuit board template. This paper circuit board is used in place of a real circuit board. So in place of soldering, you only need to twist your connections together.
To build a lie detector, you will also need some wire (18 gauge preferred), a 9 volt battery and battery clip, 2” Ω speaker (many other speakers will work too), 2 alligator jumper cables, and 2 paper clips (metal ones, with no plastic coating).
This simple, sound-producing circuit is a perfect for anyone looking to experiment. The same circuit can be used to make many different alarms and musical devices. See www.deweymac.com for more details.
The lie detector works on a principle called galvanic skin response. Basically, it detects sweat, which usually happens when someone lies. Sweat increases the conductivity (ability to let electricity pass through) of your skin. Your sympathetic nervous system controls the sweat glands on your fingertips and is completely subconscious (not controlled by you). When caught in a lie, these fight-or-flight nerves are alerted. Your body will sweat a little. The sweat will cause the electricity to flow in higher amounts and produce a higher pitched sound from the Interrogator 3000.