Pulsed VS Constant (LED related)

Discussion in 'General Electronics Chat' started by cjdelphi, Apr 6, 2009.

  1. cjdelphi

    Thread Starter New Member

    Mar 26, 2009
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    2
    I noticed the forward current can be up to 100ma for a super bright LED, but this 100ma is peak not a constant, and after doing some digging pulsing the LED every 10ms (for 1/10th of a second?)...




    .Without hooking a 555 up and trying it, would pulsing it actually make it brighter? would there be any benefit's over pulsing vs driving it at say 40/50ma constantly?....


    ( I guess my question in short is, is pulsing actually any useful for an LED, a Laser Diode i can see why, short bursts of high power even a motor for speed, but a simple LED?)


     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    282
    It would be most useful in communications, where the extra luminosity could help overriding noise or extending range.

    For simple illumination, the average power dissipation has to stay withing the limits of the LED. The pulsed technique of PWM usually gets used to dim the LED.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Most of our senses have a logarithmic response to stimuli. You might have to arrange them side-by-side to see if you can detect a difference. But 50 ma constant versus 100 ma pulsed at 50% duty cycle will probably not look different.

    Don't forget that the LED has a power limit. The overcurrent pulse has to be kept short enough that the average dissipation of the LED stays under the limit, or it will burn up.
     
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