This is a simple method for controlling a camera flash using an Arduino. The nice thing about this method is that it uses an optoisolator to separate the Arduino from potentially high voltage spikes produced by the flash. I choose to use and optoisolator instead of a relay because the response time is much quicker, which is important when dealing with split second camera timing. Being able to control a camera flash in this manner is not only useful for Photography, but can come in handy for making a haunted house display (and miscellaneous hijinks).

Step 1: Go Get Stuff

You will need:

- Arduino
- Camera Flash (with input jack)
- Breadboard
- MOC3021 optocoupler (Triac)
- 220 ohm to 1K resistor
- 3/32" mono plug
- Solid core wire

Step 2: Wire the Plug

Open the casing for your plug and solder a red wire to the center terminal pin and a black wire to the outer terminal.

Reassemble the casing.

Step 3: Wire It Up

Connect pin 13 from the Arduino to one leg of a 1K resistor.

Connect the other leg of the 1K resistor to pin 1 of the chip (this is the pin next to the dot).

Connect ground from the Arduino to pin 2 on the chip.

Connect the red wire from the 3/32" plug to pin 6 and the black wire to pin 4.

Step 4: Plug It In

Insert your plug into the trigger port on the electronic flash.

Step 5: Program and Go

Program the Arduino with the following code:

/*
  Camera Flash
  Based on basic Blink example 
  
  This example code is in the public domain.
 */

void setup() {                
  // initialize the digital pin as an output.
  // Pin 13 has an LED connected on most Arduino boards:
  pinMode(13, OUTPUT);     
}

void loop() {
  digitalWrite(13, HIGH);   // Trigger the flash
  delay(10);              // Wait for a 1/100 second
  digitalWrite(13, LOW);    // Turn off the flash
  delay(7000);              // Wait 7 seconds for flash to recharge
}

Assuming that your flash is turned on, it should now be triggered every 7 seconds.