A capacitor over led/optocoupler is no problem.
Does this look OK?
QuoteDoes this look OK? Looks fine, appart from the fact I would also have a resistor in line with the LED. The only thing limiting the current is te 470R and the 0.15uF cap, I am not sure if that will pass too much current.
you can use an AC 230V (or 110V) microrelay to send a DC signal to your arduino. Simple!
QuoteA capacitor over led/optocoupler is no problem.Except for the voltage rating it has to be.