4N28 optocoupler


I am trying to use a 4N28 optocoupler to hack a button on another device. I wanted to test it with my multi-meter first to see if it makes continuity when I send a high from my arduino. I have everything hooked up right (I think...) but no continuity.

Hook Up to the 4N28
I have a digital pin hooked up to pin 1, ground to pin 2 and continuity checking between pin 4 and 5. When I send a high out of the digital pin nothing happens.

Can I test this device with a continuity check? I thought it seemed logical...

Thanks for the help...

First you must not drive pins 1 and 2 with just a digital output and ground, you much have a current limiting resistor to keep the forward current to around 10ma or so. It's possible you might have damaged a I/O pin or the input LED of the isolator without such current limiting. Second you have to have a positive voltage and load resistor set up for the emitter/collector of the output of the isolator and use voltage measurements to check out it's proper operation. Here is a data sheet and it shows some 'test' circuits later in the document.