There is an article on Byte Craft's website on touch sensitive switches that measures body capacitance and compares it to a threshold. The measurements could be reported as an analog value. Take a look at the URL and send me private email if you have
questions.

http://www.bytecraft.com/touchsw.html


Walter Banks

Lindy Mayfield wrote:
>
> Hello Group!
>
> I am asking if anyone can help me in understanding how to create a circuit that will vary the voltage to the A/C converter on a Pic chip based on varying capacitance due to a hand or body part near a piece of metal.
>
> My idea is to create a Theremin or some sort of proximity detector.
>
> My problem is that I cannot seem to _get_ the fundamentals of this sort of circuit.  I've searched through this Piclist archives as well as the internet, and of course I've come across lots of circuits that probably provided me with the answer I'm looking for, but unfortunately I cannot comprehend the basics of how they work.
>
> I would like to begin by creating as simple a circuit as possible where I could put my hand near a piece of metal or antenna that could be sensed by the ADC.  From this point, I would be home free.
>
> Can someone help me to understand how such a circuit would work?  I would like to add that my knowledge in programming is very strong, but my knowledge of electronics is at this time quite weak.
>
> Many thanks in advance for any assistance, links, or suggestions.
>
> Cheers,
> Lindy
>

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