I am attempting to trigger a strobe, ultimately using an Arduino. I am using a 4n26 optoisolator to keep from frying my board. To test how things might work, I have attached the input of the opto to a battery pack and the strobe to the output. When I power on the strobe, the optoisolator closes the circuit, regardless of what I have on the input. I checked my understanding by measuring the output and finding that the opto's "switch" closes as I expected.

Can someone nudge me into a direction that might help me get over this hump?

 

Can you post a diagram of your hookup? We can better assist you if you do.

hgmjr