Hi Lefty,Opto-isolators were on my radar as a possibility, but I'm not sure of a good way to current-limit the input to protect the diode given the wide range of input voltages. I had thought about using a resistor in series with the input and a Zener diode in parallel with the isolator to regulate the voltage, but I believe that would limit me to DC only.Thanks,Scott
Use an opamp that works with ac and then find the appropriate resistor to limit the current to 90% of what is spec'd for at the highest voltage + maybe 5-10% you will have to check the opamp datasheet to make sure it will still work properly at the lower currents, and remember in most situations simplest is best,
"I am just monitoring when relays within the machine turn on and off"
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