Simple Lie Detector with Digital Panel Meter

If you put a 10M resistor in series, and use a 1.2V source (actually, a

1.5V battery would work fine), you'll get 200mV when the resistance is 2M, and about 23mV when it's at 200k ohms. That sounds about right.

However, your digital panel meter may have a low resistance itself, thus messing with the reading. Hopefully, it will have a 10M or higher resistance, so it won't interfere too much. If it interferes too much, come back and somebody will help you build a buffer to measure the voltage with.

HOwever, I think this circuit will be fine. Use courier font, or other monospaced font to view.

10MEG ___ + .--|___|---o------o Probe1 | | | | | | | / \ Meter 1.5V --- (_/_) - \_/ | | - '----------o------o Probe2

(created by AACircuit v1.28 beta 10/06/04

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If you need to power the meter, use separate batteries.

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Regards,
   Robert Monsen
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Robert Monsen
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Hi

I am looking for a simple lie detector cicruit for my son's science project. We have a Digital Panel Meter with a 0-200Mv range. The resistance we would like to measure would be about 0.2 - 2Mohms.

This does not need to be accurate. Help would be appreciated on how to find a suitable circuit diagram.

Thanks

Markan

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Markan

Robert Monsen wrote in news: snipped-for-privacy@comcast.com:

Robert

Thank you this works great!

Mark

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Markan

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