Stig Brautaset wrote:

> Hmmm... all this excuse of the attached picture and I forgot to attach
> it...

  Fear not.  Although some have an objection to *any* attachment, yours
is a "list-friendly" one of reasonable size although I have taken the
liberty of re-encoding it in a format more suitable.  What *really* gets
up everyone's noses is the sending of uncompressed .BMP files.

  As to the circuit itself, I fear it has the limitations others have
mentioned; it is probably *too* sensitive to its own leakeages.  Since
the PIC has an extremely high impedance already, the only real advantage
of adding external components would be to isolate it from discharges
(for which a resistor and "catch" diodes to the supply rails should
really be sufficient) or increase its sensitivity to voltage.

  I am working on touch switches myself.  I feel the best approach is to
assess capacitance using a variant on the "Stamp" circuit for measuring
same: http://www.dontronics.com/psbpix/pot1.gif  Consider the capacitor
variable rather than the resistor.
Theory at http://www.dontronics.com/see.html#pot but I'd do it a little
different.
--
  Cheers,
        Paul B.

Attachment converted: wonderland:touch.gif (GIFf/JVWR) (0001831D)