Opto-isolated zero crossing detector

[Joerg]

Jim Thompson wrote:
[snip]
Ok, yeah, then it's easy of course. But you'll have to either tap off
primary power somewhere or send isolated power across. Not that it's a
big deal to do though.
Did you look at the schematic? It's (the zero-crossing detection)
powered from the line via the 220nF capacitor.

I saw that. Might want to add 1M or something like that between line and
neutral, for discharge.

Why bother? The OP asked for a zero-crossing detector. Allusions to
opto-coupling indicates he has a transformer-isolated PS, so that
primary will dump any "Darwin" current ;-)

[snip]

There IS a discharge path, without any additions.

Nope, upon a disconnect C2 dischargeth not. Well, except across the
Darwin path you mentioned before ... bzzzt ... OUCH!