question about capacitors

Discussion in 'General Electronics Chat' started by kibbles18, Jun 27, 2010.

  1. kibbles18

    Thread Starter New Member

    Jun 27, 2010
    In my book for beginner electricians, it says that capacitators "can smooth a pulsating current from a power supply into a direct current". I dont know what this means really. What would be an example of a pulsating current? It takes in a pulsating current and outputs a DC current?
    the last question i have is when a capacitator is hooked up to say a 9V and fully charged, does it discharge right when it is charged or when something that needs electricity like a bulb is hooked up to it?
    Last edited: Jun 27, 2010
  2. Jaguarjoe

    Active Member

    Apr 7, 2010
  3. Wendy


    Mar 24, 2008
    Not too long ago I had a circuit that was feed from a 9V battery. The battery was well discharged, and the circuit put a heck of a wave on the power supply rails, around 4VP-P or so. A capacitor across the power supply rails will minimize this, the more capacitance, the better it works.

    In some ways capacitors resemble batteries. They take and hold a charge. A battery tries to keep a constant voltage for the most part (this is not a hard rule), whereas a capacitor doesn't even come close (constant voltage that is).
  4. SgtWookie


    Jul 17, 2007
    A capacitor blocks DC, and passes the effects of AC.
  5. kibbles18

    Thread Starter New Member

    Jun 27, 2010
    Last edited: Jun 28, 2010
  6. Norfindel

    Active Member

    Mar 6, 2008
    Capacitors store and release charge. For the purpose of rectification, you can look at them like a battery with very limited charge. The capacitor will take or supply current to try to avoid the voltage at it's terminals from changing, but they have limits on the amount of charge they can store and deliver.