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:

1) I could use a DPDT relay connected across the socket and energize the 
relay when I scan the socket. (Seems dangerous to me)

2) I could use the technique discussed in the Microchip App. note 
concerning AC interfacing. The problem with this is that I want to be 
able to detect the bulb without having to turn it on. I could flow low 
current through it but that would change the component values and cause 
problems when the bulb is actually turned on with full current.

I'm sure there are several other ways to accomplish this and could use 
your recommendations. To recap, I want to detect when a bulb is in a 
socket using the filament as a switch. I will use a PIC pin to monitor 
this and will use another PIC pin to turn the light on/off. The light 
will be an incandescent type operating at 120VAC and be rated at 25W.

Thanks in advance.


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