bi-directional capacitors

Discussion in 'General Electronics Chat' started by mattyleeboy, Feb 20, 2012.

  1. mattyleeboy

    Thread Starter New Member

    Jan 27, 2012
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    Hi!

    I would like to know what are bi-directional capacitors? How do they differ from other caps?

    Matt
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    You mean bipolar caps, the one you wear to disguise the OCD?
     
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  3. mattyleeboy

    Thread Starter New Member

    Jan 27, 2012
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    i mean the two 10μF electrolytic capacitors being used in the attached image
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    896
    Digikey sells Japanese non-polarized electrolytic capacitors.
    You can connect two ordinary polarized electrolytic capacitors back-to-back (negative wire connected to negative wire) to make your own non-polarized electrolytic capacitor.
     
  5. mattyleeboy

    Thread Starter New Member

    Jan 27, 2012
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    what is their function/purpose in this amplification circuit here?
     
  6. BillB3857

    Senior Member

    Feb 28, 2009
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    They couple the output of the first stage to the second stage. If the first stage output swings both positive and negative with respect to zero, then bipolar capacitor, or the arrangement shown is needed. If the output of the first stage has a DC bias level and the signal only increases and decreases this level without going through zero, then a single polarized cap could be used.
     
  7. mattyleeboy

    Thread Starter New Member

    Jan 27, 2012
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    are the two 10μF electrolytic capacitors used in this circuit the ordinary polarized electrolytic capacitors you refer to? Is the "bi-directional" (quoted for internet source) capacitor the non polarized electrolytic capacitor you refer to?
     
  8. Audioguru

    New Member

    Dec 20, 2007
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    You can buy a pretty big and pretty expensive 10uF film capacitor that is non-polar if you want.
    But two ordinary small polarized 10uF electrolytic capacitors connected back-to-back like I explained will work almost the same.
     
  9. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
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    They also make some very large ceramic caps these days if the working voltages are 35V or less. They are non polar and have better frequency response than electrolytics and are cheaper than film caps.
     
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