AC Line Monitor and/or Opto Coupler for 3.3v board

So what you want is a logic high output when there is an input signal - any signal, from 10 v up to 230V - and a logic low when there isn't? And it must be done with 1 component? What did you find at 5 volts that would do this?

Ed

Use a Transformer to step down the 230 volts to 10 volts this must be a fair sized transformer to handle 230 volts AC. then push the 10 volts through a risistor network to bring the voltage to the propper values Next use a schmidt trigger to look for voltage changes the trigger will output 5 volt and 0 volt logic high and low pulses to represent the incomming signal when it is triggered at its turn on and turn off points. This should satisfy your board feed and provide you with a logic clock pulse that represents the insomming 230 volt signal regardless of frequiency. This requires you to build the device yourself and choose the propper component values.