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Wien Bridge Oscillator

  1. Jun 20, 2009 #1
    Hi all,

    I am doing a project on electronics about the Wien Bridge Oscillator. I learned about impedances and operational amplifiers and now I'm trying to understand the Wien Bridge circuit. I'm having some problems understanding it and I would be very happy to get some help. I still have not understood why oscillations occur in this circuit, what are the conditions for oscillations to occur, and how it works mathematically. I would be extremely thankful if anyone could instruct me or relate me to some good material about it.

    EDIT: to be more specific, I've been trying to understand the analysis here:
    http://en.wikipedia.org/wiki/Wien_bridge_oscillator" [Broken]
    If it gives some more specific reference... but I am totally willing to try other materials as well.

    Thanks a lot,
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Jun 21, 2009 #2
    Can anyone please help...?
  4. Jun 21, 2009 #3


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    Science Advisor

    Check out this informative Powerpoint presentation: http://jeremya.com/engr/engr332/WienBridge-Oscillator.ppt [Broken]
    Last edited by a moderator: May 4, 2017
  5. Jun 22, 2009 #4
    Correct me if I'm wrong, but it looks like the ratio should be:
    [tex]\frac{V_O}{V_A} = \frac{Z_S + Z_P}{Z_P}[/tex]
    and the presentation says it's inverse. In addition, I don't really understand how the resistors R1 and R2 affect the system - am I supposed to multiply the right hand side of the equation above by [tex]1 + \frac{R_2}{R_1}[/tex] to get it right?
    The most significant question I have is, why does the circuit create sinusoidal voltage? I can get why oscillations will occur but I don't get why they should be sinusoidal.

    Thanks for you help :-)
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