The simple Way : use three power Si diodes in series with the line to create a voltage loss. Three other diodes anti-paralled will allow full wave transmission.
Or two diodes and a small value resistor, if there's an offset.
Then use this loss to power on the led of an opto-coupler ...an have the looked-for info from the opto's transistor.
plus a free zero voltage detector for synchro-switching !!!
so simple ...
Have a look to slave supplies sold for powering computer accessoiries ...
Alain
Bookmarks