A simple question

Discussion in 'General Electronics Chat' started by BershaM, May 23, 2012.

  1. BershaM

    Thread Starter Member

    Aug 22, 2011
    17
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    Can rectification from ac to dc be done without diodes?

    some told me it can be done with capacitors but i don't understand how

    thanks in advance
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    In the absence of a schematic I find the claim of rectification with capacitors to be dubious. The essence of rectification is blocking the flow of current in one direction, while letting it pass in the other direction. AFAIK a capacitor cannot do that.

    You could do it with a 2-element vacuum tube, which we used to call a diode before the semiconductor variety was invented.

    Why would you want to do this? Diodes are so cheap as to be virtually free.
     
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  3. Wendy

    Moderator

    Mar 24, 2008
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    No, but there are many ways to make a rectifier, usually involving dissimilar materials. Selenium and Copper layered for example. A Schottky diode doesn't have a classic PN junction.

    I read PB post after posting this, vacuum tube diodes are also a good way to go about it.
     
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  4. crutschow

    Expert

    Mar 14, 2008
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    No, it can't be done with just capacitors.
     
  5. vpoko

    Member

    Jan 5, 2012
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    If there was a DC offset in your signal (for example, a sine wave oscillating between 3V and 5V) you could use a capacitor to "bleed off" the AC and leave you with just the DC component (4V in this case), but that's probably not what you have in mind (and certainly wouldn't be considered rectification).
     
  6. BillB3857

    Senior Member

    Feb 28, 2009
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    Last edited: May 23, 2012
  7. strantor

    AAC Fanatic!

    Oct 3, 2010
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    also active rectification, with FETs or SCRs or the like.
     
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