Quote Originally Posted by The Master View Post
That sounds a little complicated. Anything upto 1000 turns :O Ive got to do this 3 times too. I think the 50Hz part will be a problem with every method.

It would be best if i could do the opto way. Problem is i think i need something daft like 20W resistors for it
Shouldn't take a 1000 turns to do what I'm thinking. I would think maybe 10 or 20 would handle it just fine. 50hz shouldn't be a problem either.
All you're doing is making a 'transformer' of a sort, tapping into the expanding/contracting alternating magnetic field that naturally surrounds a wire that is carrying a current, inducing a current into that coil, and developing a small voltage across a high value resistor which is the load for that coil.