At 12:50 PM 12/8/97 GMT+0200, you wrote:
>Hi all!
>
>I need to do some simple interfacing to 220V powerlines.
>A PIC16C84 must monitor eight different lights to determine if they
>are switched on or not. All the switches are situated together, so if
>I could find a way to "tap" the powerlines, and feed this to the PIC,
>I don't hafta lay km's of wire to the lights themselves (this won't
>be practical anywaty). I'm a little nervous about connecting mains to
>the PIC. Also, I hafta keep the component count really low, mainly
>for budget-, and space-related reasons.
>
>Anyone have some simple suggestions that could help me?
>
>Thanx!
>Gaffs.
>
>

Another possible solution is to use a phototransistor,
cadmium sulfide photoresistor, photodiode or other light sentive device to
'stare' at each lightbulb (easy to do, even in the presence of ambient light).
Convert that to a logic level and you've got a photon based light monitor.
This is the same idea principle as in an optocoupler!  :)

Gary Pepper
e-mail: gpepper@capitalnet.com