How-To Geek

Build a "Truth Meter"; A Simple DIY Lie Detector [Electronics]

One element of lie detection, as carried out by lie detecting machines, is the measurement of galvanic skin response–how sweaty the questioned person becomes. This simple electronics project recreates that measure right in your workshop.

At Make Magazine they’ve shared a guide to building your own galvanic skin response tester. It’s not a full lie detector (nor are lie detectors even as accurate as Hollywood would have us believe); none the less it’s a fun little project and a great way to learn about physiology and electronics at the same time. Watch the video above to see how they build and test it, then hit up the link below for detailed instructions.

The Truth Meter [Make Projects]

Jason Fitzpatrick is a warranty-voiding DIYer who spends his days cracking opening cases and wrestling with code so you don't have to. If it can be modded, optimized, repurposed, or torn apart for fun he's interested (and probably already at the workbench taking it apart). You can follow him on if you'd like.

  • Published 04/22/11

Comments (5)

  1. Adam

    Wow, that was so easy! All I need to do is throw that circuit board into a DeLorean DMC-12 and bam, you have a flux capacitor…..

    This is not a do it yourself for anyone but an electrical engineer.

  2. Rick S

    Hello Adam,
    I disagree. lol. That setup he has is like paint by numbers. It can be done just by looking at his video. If you already had all the parts on the table you could do it. However designing it is a different story.

    I burst out laughing when I read your comment, lol. Good one.

  3. Misty

    I built one and tested it on my husband. Broke it on the first try.

    This is not a LIE.

    Test me.

  4. ADWheeler Photography

    @Misty, maybe you should build a new husband. :-)

  5. Liam

    Great video!

    Hi, I’m currently building this circuit and I am using different diodes. They are N14148. I also was going to use tin foil instead of copper or brass foil..Any ideas on if this will work or not?

    Also, I wonder if attaching the sensors to the palm instead of the fingers would be more sensitive..

    Ps. I am building this for fun but does it actually work as a lie detector?

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