Check the SGSthomson application notes for a good demonstration of touch
sensor hardware.   Best to double check with an experienced electrician
and use resistors, capacitors with large over voltage rating if you do
this way though.

Your phrase "The pic somehow detects the touch" is a bit scary,
certainly knoledge at this level is somewhat distant from a succesful
commercial application.

Remember that the PICpins have limited static discharge protection, if
for example your finished circuit was installed in a a cold dry location
and someone walked down a long carpeted hallway.. zzzzAP goes your PIC.

You can "touch" sense in several ways:
1) resistance of finger etc pulls up/down PIC pin with very high
resistance to the other PIC supply voltage.
2) close proximity of finger etc loads capacitive sense circuit.
3) body coupled capacitivly/directly to "Earth" potential is detected
as  50/60 Hz signal referenced to active/phase wire through a VERY HIGH
RESISTANCE ie 15 mA of current can KILL!

Methods 1 & 2 are safe, method 3 should be implemented only with utmost
caution.

hope this helps,
Graham Daniel,
Electronic Product Enhancements.

John Haggins wrote:
>
> My "touch circuit" is a piece of grounded wire :)). The pic somehow detects
> the touch (I programmed it in PicBasicPro with a simple rctime command that
> measures a change) which works fine - except that I cant independently
> reproduce it in another PIC at the same time. So I guess my question is -
> is there a way to give each pic its own ground? I'm using a standard wall
> wart 9 volt adapter with no real earth pin.
>
> Alternatively, if anyone knows how to detect touch on a wire connected to a
> specific pin in a more stable way... I'd be pleased to hear about it :))
>
> thanks...
>
> >Sounds like your touch circuit needs work.
> >Is V- actually earth grounded?
> >Without knowing which way you are detecting "touch", it's hard to say.
> >It looks like the touch on plate A is bouncing the ground, such that
> >it looks like another touch occurs on plate B.
> >
> >>If I take an identically programmed pic and circuit, duplicating
> >everything
> >>except the shared power supply; I get a problem. Instead of each PIC
> >>responding independently to touch on - they both respond to the same
> >single
> >>touch on either PIC.