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Smoothing output of a full bridge

Discussion in 'Power Electronics' started by anistorian, Sep 12, 2018.

  1. anistorian

    anistorian

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    0
    Feb 23, 2018
    Hello!

    Hope someone want to help me a little bit. I was wondering, when I view schematics of a full bridge rectifier, the smoothing capacitor always seem to be non-polarized. I guess that is to let the output of the cap go into the positive rail of the rectifier output. Is that a correct assumption ? And in that case, would it be possible to use a polarized cap in series with a diode instead? Or would the voltage drop be too significant for that to work?

    Thanks in advance :)
     
  2. kellys_eye

    kellys_eye

    4,281
    1,144
    Jun 25, 2010
    The smoothing capacitor is probably only shown as non-polarised for a theoretical appreciation rather than a practical one.

    The size of smoothing capacitor is usually defined by the current draw (rule of thumb is 1000μF per amp-drawn) and you won't find capacitors of that size in a non-polarised package - unless you;re prepared to pay big money.

    Not sure what you're going on about when you state

     
    HellasTechn likes this.
  3. anistorian

    anistorian

    7
    0
    Feb 23, 2018
    Hi thanks for your reply :)
    • The smoothing capacitor is probably only shown as non-polarised for a theoretical appreciation rather than a practical one.
    Okay, so a polarized one would actually be used in most cases? Bear with me, I'm pretty new to this haha
    • Not sure what you're going on about when you state
    Maybe it's because I'm not actually sure how a capacitor work. I assumed that when you hook up the anode of the cap to the positive rail, it would spit out its charge on the kathode. And thereby smoothing the DC right before the end of the negative rail. But maybe it's the other way around ?
     
  4. Bluejets

    Bluejets

    3,505
    709
    Oct 5, 2014
    Diagram explains it......Note that this is half wave but full wave works the same.
    Cheers Jorgo
     

    Attached Files:

  5. dave9

    dave9

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    188
    Mar 5, 2017
    By being after the bridge rectifier the polarized capacitor is already in series after a diode (two actually), so adding another would be a redundant loss of another ~ 0.7V for no reason.
     
    HellasTechn likes this.
  6. davenn

    davenn Moderator

    13,314
    1,766
    Sep 5, 2009
    in ALL cases
     
    HellasTechn likes this.
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