Hi Kirk
My latest topic would interest you.
Versatile Opto Coupler 3 to 30V Input
This arrangement will accept 3 to 30V input and have a LED current go approx 5.5mA irrespective of input voltage. No series resistor needed.
For your application simply connect the output emitter to ground and the collector to Pico digital input with an external or internal pull up resistor to 3.3V. This output will be LOW active
Cheers Bob
