zero crossing detector?

dave-in-nj:
is this what you mean by "You could bung this up with resistors till Kingdom Come and still be undone."

I've seen examples of these ZCDs (mine) with a resistor placed at both ends of the input.
Which I kind of thought was your point.
I guess my point was that something bad might happen anyway.

To everyone else: If you don't have a fuse then you don't stand a chance.