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Shortening pulses with an inductor

  1. Jan 12, 2010 #1
    Hi everyone,

    quick question - I have been using a pulsed driver to pulse an LED. By placing an inductor in parallel with the LED, I can shorten the duration of the pulses from the LED. I'm looking for an explanation as to why this is the case...

    I'm guessing that the inductor act as a high-pass filter, passing the high frequency components of the electrical pulses to the LED, and blocking the low frequency components (i.e. sending them to ground) - having the overall effect of reducing the time duration of the pulse from the LED.

    Does that seem sensible? Thanks in advance for your help!
  2. jcsd
  3. Jan 13, 2010 #2


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    Science Advisor

    Pulse on inductor.PNG

    That sounds like the normal effect you get with an inductor when you apply a pulse to it through a resistor.


    The effect varies with the frequency and the size of the inductor.

    The green trace is the voltage across the inductor and the white one is the applied pulse from a function generator.
    Last edited: Jan 13, 2010
  4. Jan 13, 2010 #3
    Why waste output current with a parallel inductor when a series capacitor will do the same thing? A parallel inductor on a voltage source output will wreak havoc and add I2R heating on the output circuit of a voltage source.
    Bob S
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