can the capacitor withstand?

Discussion in 'The Projects Forum' started by onlyvinod56, Apr 4, 2009.

  1. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    Hi.
    In a 7812 based regulated power supply circuit, it is mentioned that to use a 220uf capacitor between pin1 and ground. That transformer im using is a 230/12v.

    I have a 220uf/16v. Does this cap withstands for the 12v pulsating DC?
    Someone told me that, if the voltage is 'x' volts, we need to use a capacitor of '2x' volts.
    Is it right?
     
  2. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    The 16 volt rating is cutting awful close and I wouldn't recommend it for long term reliability. Assuming you are using a full wave rectifier the peak DC value will be 16.9v minus two diode forward voltage drops, say 1.2v, so 15.7 peak at the filter caps. Any upward variation in the AC line voltage would bound to push this higher at times. On the other hand the maximum voltage rating of caps are usually a conservative rating and won't be destroyed exactly at their rated voltage.

    As Clint Eastwood asked, "are you feeling lucky, punk" ;)

    Lefty
     
  3. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    wat about this? check the attachment.
    1. wat is the voltage rating of 2.2uf in the fighur?
    2. Is there any special consideration fro the 0.33uf?

    I can find the voltage specification on an electrolytic but wat about the 0.33uf?
     
  4. flat5

    Active Member

    Nov 13, 2008
    403
    17
    Use 50v or 100v caps.
     
  5. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    ok. thank you
     
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