How does this circuit work?

Discussion in 'General Electronics Chat' started by asdff1818, Dec 20, 2009.

  1. asdff1818

    Thread Starter Member

    Dec 7, 2009
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    Hi, can someone help me understand how this circuit works, I know what transistor, collectors, and resistors are, but what are their function in this circuit, and how does it work part by part? And how accurate is it? I am doing project on this, to find out if skin perspiration changes when one lies. How accurate is it (at measuring perspiration, not at detecting lies)? And also, what type of meter should I use (ohm meter, volt meter, amp meter, or etc)?

    http://www.aaroncake.net/circuits/lie.asp

    Thank You!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. asdff1818

    Thread Starter Member

    Dec 7, 2009
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  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    That circuit uses skin conduction to partially turn on the transistor. It will work very differently on a hot day than a cold one.

    Did you read the articles?
     
  5. asdff1818

    Thread Starter Member

    Dec 7, 2009
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    I still don't understand exactly how everything works. How? And why isn't it accurate?
    Why?
    Yes, the first one is kind of confusing, where is the circuit? There are two shown there. And the second one says that he wrote a simple data logging program that records the RAW sensor value every 10 seconds into a file, but doesn't give us the code.

    Thank You!!!!
     
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