John,
I think I would try somthing like this.

main---------switch---------light bulb---------main
  !                          !
  !                          ! 
  !---------resistor------diode----to pic

The resistor is a pull up resistor.  The light bulb will drive the 
output to 0
You will need to scale the output to "Pic" range
bill


John Walker wrote:

>Hi all! Long time lurker, first time poster.
>
>I am working on a project where I want to use a PIC pin to detect that 
>an incandescent light bulb (120VAC 25W) has been inserted into a 
>standard light socket. I want to do this by using the fact that when a 
>bulb is in the socket its filament will act as a sort of switch across 
>the socket contacts. There are two ways I can think of doing this:
>
>  
>

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