LED indicator help

Discussion in 'The Projects Forum' started by wolf08, Jan 14, 2010.

  1. wolf08

    Thread Starter New Member

    Dec 14, 2009
    14
    0
    I am making a control panel for may project and i have no idea how to make an LED turn on or off when my capacitors are done charging.

    Thanks:confused:
     
    Last edited: Jan 14, 2010
  2. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    A simple window comparator will do this job. Are you familiar with the LM339, and a window comparator? Basically it is a voltage divider on one input, and the capacitor voltage on the other input.

    Figure what number you want to call charged (say 95%).
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    If your supply V is greater than 36 V , a V divider will be necessary from Caps to ground.
     
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