I'm using a 4N35 optocoupler to trigger a camera shutter from the Arduino. Is it safe to power the optocoupler directly from a digital pin on the Arduino? Datasheet for the 4N35 says its 1.9V and 60 mA to power the internal LED on it. The Arduino Mega documents say the max per pin is 40 mA, but at 5V. Safe or not safe to hook it up directly? By safe I mean will it fry the Arduino.
I'm starting to know enough to know how much I don't know, know what I mean? [smiley=shocked.gif]
You will need a 330 ohm resistor in series with the opto LED input to safely drive it from an Arduino output pin. The 60ma LED rating is the maximum safe LED current that the opto can handle but all it's data sheet specs are based on an LED current set to 10ma and it will work just fine at 10ma.
Thanks for the quick replies. I just tested it with some LED output and its working great. Will try it with the camera tomorrow. Also glad I've made it to the 1st order of ignorance! Still got a long way to go though. Cheers!