Simple Lie Detector

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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.

Schematic

Parts

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)

Notes

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.

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.

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Comments

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dipa Simple Lie Detector Thursday, January 28, 2010 4:14:10 AM

I maid this project but it does not work.Please tell me how does it really work.

Naomi Hays Simple Lie Detector Tuesday, January 26, 2010 5:11:45 PM

Can you put step by step directions on how to build this or can you send it to me in an email because i am building a lie detector test for science fair and i don't understand this picture (p.s. i'm only in 8th grade). So can you please do me a favor and simplify this? Thank You

namit Simple Lie Detector Tuesday, January 19, 2010 11:45:49 AM

should have seen this much more earlier

vineeth Simple Lie Detector Tuesday, January 05, 2010 10:15:50 PM

is the analog meter AC or DC

Es Simple Lie Detector Tuesday, January 05, 2010 11:26:40 AM

Can i use 2N3904 instead of 2N3565?

anonymous Simple Lie Detector Tuesday, January 05, 2010 7:23:15 AM

this lie dictator is looking awesome.... but it's very baaaaaaaaaaaadd...........

akshata Simple Lie Detector Sunday, January 03, 2010 11:18:43 AM

i wanted to know whether i can place red/green led's in the circuit to indicate a lie . please reply soon .thanx

Mati Ullah Simple Lie Detector Friday, January 01, 2010 2:00:03 AM

what is the use of transister in this circuit? plz explain shortly the operation of the circuit why v have introduced the VR2, transister and two source voltage instead of one 9 volt.??

Mike H. Simple Lie Detector Friday, December 18, 2009 1:31:48 AM

Hi, Is at all possible to incorporate a green and/or red LED in the circuit? So say you ask a question and its a lie the LED lights up. I am new to electronics so where would I place the LED? Thanks Mike H.

waseem afzal Simple Lie Detector Monday, December 14, 2009 5:30:52 AM

oh yeh that;s working superb

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dipa	Simple Lie Detector	Thursday, January 28, 2010 4:14:10 AM
I maid this project but it does not work.Please tell me how does it really work.
Naomi Hays	Simple Lie Detector	Tuesday, January 26, 2010 5:11:45 PM
Can you put step by step directions on how to build this or can you send it to me in an email because i am building a lie detector test for science fair and i don't understand this picture (p.s. i'm only in 8th grade). So can you please do me a favor and simplify this? Thank You
namit	Simple Lie Detector	Tuesday, January 19, 2010 11:45:49 AM
should have seen this much more earlier
vineeth	Simple Lie Detector	Tuesday, January 05, 2010 10:15:50 PM
is the analog meter AC or DC
Es	Simple Lie Detector	Tuesday, January 05, 2010 11:26:40 AM
Can i use 2N3904 instead of 2N3565?
anonymous	Simple Lie Detector	Tuesday, January 05, 2010 7:23:15 AM
this lie dictator is looking awesome.... but it's very baaaaaaaaaaaadd...........
akshata	Simple Lie Detector	Sunday, January 03, 2010 11:18:43 AM
i wanted to know whether i can place red/green led's in the circuit to indicate a lie . please reply soon .thanx
Mati Ullah	Simple Lie Detector	Friday, January 01, 2010 2:00:03 AM
what is the use of transister in this circuit? plz explain shortly the operation of the circuit why v have introduced the VR2, transister and two source voltage instead of one 9 volt.??
Mike H.	Simple Lie Detector	Friday, December 18, 2009 1:31:48 AM
Hi, Is at all possible to incorporate a green and/or red LED in the circuit? So say you ask a question and its a lie the LED lights up. I am new to electronics so where would I place the LED? Thanks Mike H.
waseem afzal	Simple Lie Detector	Monday, December 14, 2009 5:30:52 AM
oh yeh that;s working superb