I had this old flash lying around and I thought I would try to hook it up to an arduino. A bit of googling told me that an optocouper would be the way to go to shield the arduino from the high voltages.
Everything seemed simple enough, but I just can't get it to work.
I opened the flash and hooked wires up to the flash test button. Removing the little button even gave a nice hole for the wires to go through. Touch the wires together and the flash goes of.
I used a 4N35 optocoupler, a PS4N35V to be exact. I hooked a digital pin up to pin 1 on the optocoupler through a 220 ohm resistor. Pin 2 to ground. I hooked the flash wires up to pin 4 and 5. I'm guessing polarity isn't an issue here since I'm just closing a circuit.
I then wrote a super simple test code writing the digital pin plus the pin 13 led high for a second then low for 10. Led is flashing but the flash isn't going off.
I've looked at a couple of other projects and it appears I'm doing the right thing. Am I missing something obvious here?
I tried putting an led with an external power supply in instead of the flash and that works fine. It flashes in sync with the onboard led.
One thing I've noticed is that when I connect the flash to the optocoupler it goes off. I thought that pin 4 and 5 wouldn't be connected unless there was current through 1 and 2. I must be misunderstanding something.
Any advice would be very much appreciated.