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LED Delay ideas?

Discussion in 'LEDs and Optoelectronics' started by Mickc, Aug 2, 2013.

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  1. Mickc

    Mickc

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    Aug 2, 2013
    Hi guys, first post!

    I am building an aircraft simulator panel that has 32 LEDs in it, that are all run individually by a Phidgets LED-64 Board.

    On the real aircraft, these LEDs are lit up when a sensor is triggered, and while they all illuminate more or less together, there is a a very small delay between each LED due the mechanical "free play" in the linkages and sensors.

    So basically what I want to do, it have a very small delay on the LEDs turning on and off, but be different for each LED to create the illusion of the real operation as described above..

    All the LEDs are turned on at the same time, and there is no way to write this "randomization" into the software driving the board.

    Any ideas on how I might accomplish this?

    Cheers.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
    2,838
    Jan 21, 2010
    There are a number of ways to do this.

    One way is to have a pseudo-random signal source connected to clock a D flip flop that is associated with each LED. To turn on, the LED requires both a signal to turn on, *and* a clock pulse. Because the clock pulses are random, even if you signal each LED to be on at the same time, they will turn on some random time thereafter (the same will happen when you turn them off).

    This sounds really good, and in practice could be made quite realistic, however the amount of circuitry required for each LED would be comparatively large.

    Another approach would be to use a microcontroller. This could keep a list of the LEDs in an ever-changing order (using an internal pseudo-random number generator. When the signal arrives to turn the LEDs on, it could turn them on in the current sequence with a small random time between each LED.

    The latter solution requires a bit of fancy programming and may require tweaking to get a realistic appearance.

    Another way might be to use an RC circuit and some schmitt triggers to delay the edges of the signals. This would introduce a small (but mostly fixed) delay for each LED. It could be tweaked to look realistic, but would likely have a fixed order.
     
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