Friday, 2 December 2011

Lie detector circuit

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.
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.

2 comments:

  1. how does the circuit actually works?i mean what each components exactly do?

    ReplyDelete
    Replies
    1. The NPN transistor functions main.
      Through electrodes brain resistance increase when a man lying, and convert to electrical signal, into the metere
      .

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