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Smoothing with full wave rectification

  1. May 12, 2005 #1
    Hi all!

    Is it possible to produce a smooth(or almost smooth) voltage through full wave rectification? I know for half-wave, you can use a capacitor, but this doesn't seem to work for full wave.

  2. jcsd
  3. May 12, 2005 #2


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    Sure it does. You may need to provide more information about what you are doing. IIRC, since a full wave rectifier has twice the ripple frequency of a half wave rectifier you will need to use a different valued cap for optimal performance.
  4. May 12, 2005 #3


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    You don't need to use a different cap, but you can get by with a smaller one. That is what engineering is all about though, getting by with as little as possible and still having things work correctly.
  5. May 12, 2005 #4
    I think the diagram that I have attached achieves that, I did not test it properly in pspice though. The DC source represents your full wave rectification and the voltage across R1 should be smoothe enough

    Attached Files:

  6. May 13, 2005 #5
    hi guys thx for ur replies!

    What i am trying to do is to produce a smooth voltage to power an xray tube. I am trying to convert the AC currect into a DC current then smooth the voltage out so that the peak voltage is effectively the average voltage.

    Exequor: What is L1? I'm not very good at this so can you please explain a bit how your circuit works?

    Last edited: May 13, 2005
  7. May 14, 2005 #6
    Go to my website www.abiscus.com and go to the rectified power supply link. On that page you'll find a PDF file explaining the theory behind rectification.

    For a fullwave rectifier, the equation for the capacitor C is:

    C = Vp / ( 2 * R * f * Vr )

    where Vr is the voltage ripple, f is the frequency, R is the load resistance, and Vp is the peak voltage of the input.

    As you can see, the larger the capacitance, the smaller the ripple voltage and the closer you will come to a smooth DC value.

    You may also want to think about using a voltage regulator. This helps keep the DC voltage constant and further dampens the ripple.
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