As an input I have a AC signal with a range of 0-220VAC.
I just want to make a simple switch to know whether the AC is on/off
off = 0-10VAC
grey area = 10.1-19.9VAC
on = 20VAC and above
I was thinking of using a photocoupler (PS2705-1) for this but I have been making the calculations and I will be highly dependent on the current transfer ratio (which has quite a big range, 50%-300%). I plan to make more than ten of these and I dont like to recalculate resistor values for each piece
Aside from buying a tight range photocoupler, what else could I use?
EDIT: added attachment of schematic.
there are three resistors in the input because I only have 1/4W resistors here.
schematic shows 4N35 but i plan to use PS2705-1