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Wien Bridge oscillator

Discussion in 'Homework Help' started by stobbz, Mar 30, 2011.

  1. stobbz

    stobbz New Member

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    Hello, I'm doing some work with Wien Bridge oscillators and having a look at some of theory.

    Apparently oscillation occurs at the resonant frequency = 1/2*PI*R*C

    However, if you apply the Barkhausen criteria for oscillation you get a completely different expression for oscillation frequency, in my case f = 1/R*C

    What is the difference between the two?

    Thanks!
     
  2. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Stare at this:

    At what frequency is the phase shift exactly 0 degrees?

    What is the loss (in db) at that frequency?

    Relate that to the formulas you posted.
     

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    Last edited: Mar 30, 2011
  3. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Notice what happens if the Wien network is connected to a non-inverting amplifier with gain slightly higher than 3 (9.54db), and is given an initial perturbation.
     

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  4. dave

    Dave New Member

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  5. stobbz

    stobbz New Member

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    Thanks a lot MikeMl, those were really helpful. I feel stupid for asking the question now, having woken up feeling (relatively) refreshed, I can see that one expression simply gives the oscillation frequency in Hertz and the one I derived gives it in Radians... D'Oh!

    Thanks again MikeMl!
     

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