Capacitors in oscillators

Discussion in 'General Electronics Chat' started by aamirali, Feb 28, 2012.

  1. aamirali

    Thread Starter Member

    Feb 2, 2012
    415
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    What is the functions of capacitors in oscillators.
    1. One they provide 180 phase shift along with oscillator combined.

    Won't these capacitors interfere in oscillator operation by providing low resistance path to ac signals?
     
  2. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
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    First, what kind of oscillator are you talking about. There are several.
     
  3. aamirali

    Thread Starter Member

    Feb 2, 2012
    415
    1
    oscillators which we use in MCU for clock.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    1,605
    These oscillators can and probably should be approached with a "Simon sez" mental outlook: just follow what the data sheet says and don't over think it.

    Those caps form part of the feedback network and are required to get the proper phase shift so the dang thing oscillates in the first place.
     
    Sparky49 likes this.
  5. buzaiandras

    Member

    Jul 18, 2011
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    I am also interested in this topic.
    How exactly do they (the capacitors) contribute to the feedback.

    Could you (or somebody) please explain it in more details?

    I searched for this info for a long time but could not find much about the role of the capacitors :(. (I mean explained in more details :) )

    Thank you
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    Take a look at the attached PDFs.

    Bertus
     
  7. Mark_T

    Member

    Feb 7, 2012
    47
    8
    The caps in most oscillators are part of a resonance circuit when combined with another component(s). But in crystal oscillators they are not part of the timing components. They are there, depending on exact configuration, to block DC, pass the Osc freq, or provide AC feedback, maybe even providing damping for the crystal.

    Just follow the data sheets...there's more to them there crystals than we know....
     
  8. aamirali

    Thread Starter Member

    Feb 2, 2012
    415
    1
    What's the difference b/w crystal oscillator & pierce oscillator?
     
  9. bertus

    Administrator

    Apr 5, 2008
    15,648
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    Hello,


    Here is the complete wiki page:
    http://en.wikipedia.org/wiki/Pierce_oscillator


    Bertus
     
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