Long story short, I have an input of 4-125VAC I need to measure with a comparator. Preliminary testing shows I'll need my threshold to be around 12V. The comparator portion is easy.
My problem is the variable voltage, or I'd just use a cap dropper to drive the opto.
My thoughts are a simple full bridge with a series resistor with a zener. To keep the dissipation down, I'd shoot for something like 220k or 330k. I don't remember the op amp's input current requirements off the top of my head (LM358 ....have a ton laying around).
Usually, I'd just use a zener to limit the voltage, but will the 1mA or less cause issues with the zener?