LED High frequency Strobe

Discussion in 'The Projects Forum' started by Mechanic, Apr 2, 2013.

  1. Mechanic

    Thread Starter New Member

    Mar 26, 2013
    I am actually a mechanical engineering student and fairly new to circuits.

    For my graduation project, I am building a test-setup in which we use a camera setup. To avoid having to use a high speed camera, we are looking into two exposures per frame to do PTV.
    For that reason I looked into high power led-modules and am looking into a circuit that makes the LEDs flash at a clearly defined interval at a clearly defined speed.
    Furthermore the circuit must accept trigger signals to be able to synchronise the camera. The camera sends out a pulse every time it takes a shot.

    The pulses I need are of 0.1-1 ms and the times between the pulses in the same order, but always larger. I found the circuit posted below for the astable oscillator that puts out such a signal.

    I found out the following project for driving high power LEDs http://forum.allaboutcircuits.com/showthread.php?t=32364.

    I am now wondering whether I can actually switch the LEDs that quickly. And I furthermore wonder how should I incorporate the triggering?

  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    LEDs can switch in the microsecond range. Check the DATASHEET of a specific LED. Higher power may be slower. Search LED above 75 mA on digikey.com.
  3. sheldons

    Active Member

    Oct 26, 2011
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    I once did an experiment to see how fast I could pulse a LED and still see it.

    Damn, was so long ago I forgot how fast it was, but I believe it was under a microsecond, perhaps even 20 uS, and still quite visible to my eye from across the room.
  5. bertus


    Apr 5, 2008
  6. Markd77

    Senior Member

    Sep 7, 2009
    0.1ms is no problem. The IR LED in a TV remote control runs at 36kHz and they are pretty much the same as visible LEDs.
    If you only want to send two pulses, you might have to add a small delay at the start because otherwise they might have happened by the time the camera shutter is open.
    Last edited: Apr 3, 2013