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rc timing

mctriviamctrivia Posts: 3,772
edited 2009-02-17 20:14 in Propeller 1
trying to remember the math it has been a while.

if input is a pulsing 3.3v how do I calculate to keep the led on for 62uS after power is removed?

Post Edited (mctrivia) : 2/17/2009 7:00:09 AM GMT
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Comments

  • CannibalRoboticsCannibalRobotics Posts: 535
    edited 2009-02-17 18:53
    Assuming the input to the left of the capacitor is tri-state and left floating, you've got to know the forward resistance of the LED, call it Rl. Add R and Rl for your total discharge resistance or Rt. The discharge time is Rt * C I believe. Just remember the discharge curve is not linear but approximates it in sections.
    Jim-

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  • mctriviamctrivia Posts: 3,772
    edited 2009-02-17 19:25
    hm forgot about the need for tristate input. guess I will have to use something else.

    pretty sure diodes can't be calculated as resistor
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-17 20:02
    hm forgot about the need for tristate input. guess I will have to use something else.

    pretty sure diodes can't be calculated as resistor
  • dMajodMajo Posts: 855
    edited 2009-02-17 20:14
    http://openbookproject.net/electricCircuits/DC/DC_16.html
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