Caps Blocking DC?

Discussion in 'General Electronics Chat' started by SlowCoder, Apr 1, 2012.

  1. SlowCoder

    Thread Starter New Member

    Mar 25, 2012
    26
    0
    I've attached a circuit from my workbook. I have questions about it.

    1. When I press S1, why would the cap pass any current at all across its dielectric? I mean, I understand that a very small amount may pass, but why enough to flash the LED? And why only pass it very briefly while it charges, then stop?
    2. When I press S2, which discharges the cap, why does it not flash the LED as it discharges?
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    Caution: this is not a safe circuit.

    If someone presses both S1 and S2 at the same time, you will end up with a blown LED.

    To prevent this, place a 470-ohm resistor in series with the LED.
     
  3. SlowCoder

    Thread Starter New Member

    Mar 25, 2012
    26
    0
    Yeah. I'd actually thought about that. I'm always very careful when I do stuff, but you never know ... accidents do happen. I'll probably start doing that, as long as the circuits are simple.
     
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