• Flash trigger

    This sections hosts my current (at least one of them) project: An arduino controlled flash trigger using a laser beam.

    The aim of this project is taking high-speed photographs without using a high-speed camera :-)

    You can get a preview in the following video:


    Arduino flash trigger from Quercus on Vimeo.

    This project is mainly based in this one from Glaciar Wanderer. I just liked his idea and worked it on my own. (I think this guy and me would be friends, as the projects he has in his photography category are things I’ve been wanting to do since I got my Arduino :-)

    I will not be using a microphone as sensor, at least not right now. On the other side I am using a transistor to control the laser instead of using a digital output of the arduino board directly, as I pretend to use more than one laser, and using a transistor will allow me to draw more milliamps than the Atmel chip can provide.

    I also added a couple of leds to monitor when the laser is aligned and when the beam is crossed:

    (Click on the images to see them in a Flickr album, as they have notes on it.)

    Here you can see how everything is setup:

    For the impatient, you can already access the arduino code here

    And below is the schematic:

    I used a 4N26 optocoupler to trigger the flash, connected to a hotshoe-to-pc-sync adaptor in my Vivitar 285HV. Using an optocoupler you get sure that no current from the arduino will go to the flash, and no current from the flash will go to the arduino. Anyway, you should check the trigger voltage of your flash, as if it has a high voltage (even hundreds of volts) it could damage the optocoupler and everything that is connected to it (arduino, computer, you…).

    In the 285HV the center pin is the “live” one, thus it is connected to pin 5 of the 4N26, you should check this in your flash, as I think some brands have this “swapped”. For this I used my camera and flash trigger module

    As the laser I used a simple laser pointer (the ones you can buy in gift shops). I will probably break it apart to access the circuit and use another optocoupler to turn it on/off, but so far I’ve duct-taped the on/off button and control the laser using a BD137 pnp transistor that acts as switch.

    Common items:
    1x Arduino board

    For the flash trigger:
    - 1x 330 Ohm resistor.
    - 1x 4N26 optocoupler.

    To control the laser:
    - 1x BD137 transistor.
    - 1x 10K Ohm potentiometer for fine tuning.
    - 1x 57 Ohm resistor (that I will probably remove soon).

    For the led indications:
    - 1x red led.
    - 1x green led.
    - 2x 100 Ohm resistor.

    To sense the laser light:
    - 1x LDR.
    - 1x 1K Ohm resistor.