PicDude wrote:

> Thinking of using the case on a PIC-based project as a simple
> touch switch.  Can anyone comment on if this idea will work...

If you want simple, how about putting just a resistor into a port
pin? Say 470K.

Output a square wave at a high frequency. On each transition
temporarily make the port pin an input and sample it. If the input
follows the output there is no contact. Anything else and there is a
contact.

When a person touches the contact you may get anything such as all
low, all high, 50/60Hz hum, delayed output signal caused by
capacitance of the person, local radio station etc...

Who knows if it will work? You could add some clever software
filtering to try and get the kind of response you want.

The resistor gives some ESD protection. Worth a try?

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Brent Brown, Electronic Design Solutions
16 English Street, Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile/txt: 025 334 069
eMail:  brent.brown@clear.net.nz

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