You want a current sensor.
but I would zero idea (and zero confidence in) how to hook that baby to 230AC.
Hmmm. A 330v AC capacitior makes me nervous.http://www.grainger.com/product/DAYTON-Start-Capacitor-2MEL3And it's US$13.
See, I'm confused because the specs on the 4N33 say:Input Type DCNumber of Channels per Chip 1Maximum Input Current 80mAMaximum Reverse Voltage 5VOutput Type DCMaximum Forward Voltage 1.5V
What is the problem with that?The diode makes the input DC and stops any reverse voltage.
then how is there not a large reverse potential across the input side of the optocoupler ?