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Capacitors in rectifier circuits

  1. Apr 25, 2008 #1
    I'm a bit stuck with rectifier circuits. can anyone tell me what the function of a capacitor is in a rectifier circuit please.

    Thanks, Dave
  2. jcsd
  3. Apr 25, 2008 #2


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  4. Apr 29, 2008 #3
    I personally look at this in two different ways:

    First, capacitors have a low impedance to AC signals, and keeps decreasing as as freq increases, and a high impedance do DC signals. When you put the shunt capacitor in place, you create a current divider network that basically absorbs the AC component of the voltage signal, thus leaving only the DC component.

    EDIT: Note that current divides proportionally in such a way that most current flows through the path of least resistance. This explains why AC current is "absorbed" by the shunt capacitor.

    The other is that since capacitors refuse to instantaneously change their voltage, they tend to smooth out fast voltage transitions, in this case, the ones occurring in the half/full rectified signals present after the rectifying diodes, once again creating a more DC like signal.
    Last edited: Apr 29, 2008
  5. Apr 30, 2008 #4


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    It might be best to think of the cap as energy storage for use when the diodes are not conducting.
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