I'd like to sense the presence of 24VAC in a couple of different places.
I've sensed multiple 5VAC lines before (coming in from current transformers linked to transistors) by just taking the whole port of inputs and ANDing it against a variable that starts as 0xff. I'll do the AND operation 20 or so times with 1ms delays between. Any zeros that come through are captured. That works fine.
24VAC is a little different. I'm not sure how to handle it safely. I've looked up optoisolators on Digikey but there is no input voltage column to sort by and all models I select have very low input voltages.
Does anyone know of a simple and cheap circuit or IC that can at least bring the 24VAC down to 5VAC or does something else that's also useful that I haven't thought of yet?