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Hallowen project (LED)

Discussion in 'LEDs and Optoelectronics' started by Metatron, Sep 1, 2012.

  1. Metatron

    Metatron

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    Sep 1, 2012
    I wanted to back-light a canvas and produce a flashing red LED light in a sequence mimicking lightning. A suggested sequence of: Off 5min, charge Capacitor, produce a flash of light (six flashes @ 35hz, off 1sec , 2 flashes @ 35hz) off 5min...repeat
    I was going to use a 555 timer to achieve this, but need some direction on where to start...

    I have built the canvas and back light, I just need to build the circuit to flash the image.

    BT
     
  2. BobK

    BobK

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    1,641
    Jan 5, 2010
    You cannot do that with a single 555 timer. You would need several and some other logic. You would be much better off with a microcontroller.

    Also, where did 35Hz come from? At that frequency, it would get at most a shimmering effect, not flashing like lightning.

    Bob
     
  3. KJ6EAD

    KJ6EAD

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    Aug 13, 2011
    I've simulated lightning quite effectively by using a sound to light circuit driven from a thunder sound effects track.
     
  4. Metatron

    Metatron

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    Sep 1, 2012
    KJ6EAD> Great idea!. especially since I already know how to build one.
     
  5. CocaCola

    CocaCola

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    Apr 7, 2012
    If you are not doing it reactive to sound like KJ6EAD suggested, and getting a more analog effect... You really should develop a more complicated digital scheme so it doesn't look just like a simple flash...

    I would do this with a micro a Bob suggested, and would explore a scheme like this...

    When there is a flash, multiple LEDs would go on steady to give an overall low glow (maybe use blue LEDs to add a subtle color effect), while other banks (white LEDs) would double and triple pulse rapidly to add a brightness effect to the overall glow... Turn off all LEDs between flashes and do it again... The rapid double and triple pulse isn't as 'digital' on the eyes, couple that with the background glow that is constant over the entire flash it's much more eye pleasing...

    When you do it this way you get a more realistic analog looking flash vs the really easy to pick out on/off of the digital flash, this same principle of leaving a steady light on, with overlaid flashing also works well to simulate candle or fire...
     
    Last edited: Sep 2, 2012
  6. Metatron

    Metatron

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    Sep 1, 2012
    I would really like to do it with a micro controller...
    Which one would you suggest. I worked with an Moto x8600 in school and a very small bit with an Arduino.
    Great idea using an ambient glow behind a flash.
     
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