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Simple Lie Detector

Discussion in 'Electronic Projects' started by ElectroMaster, Jul 19, 2002.

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  1. Roff

    Roff Well-Known Member

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    They are equivalent as shown below. The designer may have used two batteries because he didn't feel any need to reduce the number of batteries, or didn't know how.

    PS as Audioguru says, you can use 9V batteries.
     

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    Last edited: Oct 9, 2006
  2. sippi3000

    sippi3000 New Member

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    can some tell me why onc i power up my lie detector my meter is at full power so i cant measure resistance
     
  3. Roff

    Roff Well-Known Member

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    Post your schematic and we'll take a look at it. What is your meter's full scale current?
     
  4. dave

    Dave New Member

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  5. ismlamour

    ismlamour New Member

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    thans>>>>>>>>>>>>>>>>>>>>>>>>>
     
  6. Science Mac

    Science Mac New Member

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    hello fellow people i wanted to see how to build the circuit because of the connection between the second resistor and the analog meter
     
  7. Roff

    Roff Well-Known Member

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    What does this mean? If you can't read a schematic, describe what you need to know in detail.
     
  8. cheystar

    cheystar New Member

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    a noob question here. this circuit is placed on a board right? the ones with holes? Also wires used to connect each component is stranded 18 gauge insulated wire ok?
     
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    18 gauge wire is too big for the small holes in a circuit board.
    Use 22 gauge solid tinned copper insulated hookup wires.
     
  10. CuentaChocula

    CuentaChocula New Member

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  11. nightcatz

    nightcatz New Member

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    can I use any npn replacing the 2n 3565

    hi ...electro master can I use s9014 in lieu of 2n 3565 ..pls help
     
  12. Roff

    Roff Well-Known Member

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    S9014 will work just fine.
     
  13. Peter_wadley

    Peter_wadley New Member

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  14. nightcatz

    nightcatz New Member

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    hi guys can anyone tell me If I can use digital ammeter of the Digital Multimeter in lieu of the analog meter .......I dont have a analog meter in my place and allelectronics.com says it cannot ship the product to my place
     
  15. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The lie detector project sometimes lies.
    It measures the resistance of skin and the resistance of its connection to skin. It is supposed to use a 1mA moving coil meter so you can see the meter's needle move. A digital meter will just be a blur of changing numbers if anything changes.
     
  16. nightcatz

    nightcatz New Member

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    thanks the info audioguru ......can u tell me if using the digital ammmeter can spoil the multimeter
     
  17. audioguru

    audioguru Well-Known Member Most Helpful Member

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    What will its max current of only 1.5mA do to a multimeter?
     
  18. hates

    hates New Member

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    It is a cool project
     
  19. audioguru

    audioguru Well-Known Member Most Helpful Member

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    It measures the resistance of the connections to the victim, not if they are lieing.
     
  20. sheng_james

    sheng_james New Member

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    nice topic. im gonna try this one.
     
  21. HiTech

    HiTech Well-Known Member

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    It banks on the fact that a person may have sweaty palms while lying, creating a change in skin conductivity. A better circuit would measure pupil dilation and overall eye movement. Typically, the eyes don't lie!
     
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