That's the only one I have on hand that meets voltage spec. If I wanted to do it like that any npn transistor that meets voltage spec would be fine?
In pinmode, enable the pull up resistor and nothing else is needed on the input side from the collector to Arduino?
The (-) ac leg would just be hooked to ground?
I'll try with a transistor on the scope first and see how it behaves, then might decide on a optocoupler, thanks.