>But I was thinking there may not be enough movement.
>However using capacitance I probably wouldn't need to
>move very far to see a big change in freq.  Any thoughts
>on this anyone?  Whould a switch or capacitance work better?

Try using a CD4046 PLL as a capacitance change detector. If the varying
capacitance is the frequency determining C in the PLL you should be able to
set the desired sensitivity by determining the max-min frequency swing for
the control voltage range. You could then measure the control voltage with
an ADC, or if you can get the swing suitable just feed it into a Schmitt
trigger to get a digital signal.

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