Variable frequency sine wave

Discussion in 'The Projects Forum' started by gagan, Sep 20, 2009.

  1. gagan

    gagan Thread Starter New Member

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    hey guys. I want to build a variable frequency sine wave generator with a constant amplitude. any suggestions??

    Thanks,
    G
  2. Audioguru

    Audioguru New Member

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    A Wien Bridge oscillator using a light bulb or a Jfet for amplitude stabilization works well.
    Mine goes from 10Hz to 100kHz.
  3. gagan

    gagan Thread Starter New Member

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    hey thanks for the quick reply

    I'm considering the following circuit
    http://www.national.com/ms/LB/LB-16.pdf
    Figure 1 Easily tuned sine wave oscillator

    Can any one help me by explaining what exactly how sine wave is being genrated in the circuit.

    Audioguru:- I did consider wien bridge option but can't figure out how to control the amplitude using jfet exactly. If you could explain a bit more on that part, then it will be great.

    Thanks
  4. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    Dallas, TX (GMT-5 w/ DST)
    How pure does this sine wave have to be? If the answer is not extremely, then you can use other methods.

    [​IMG]

    To answer your question the Zeners clip the wave form, leaving what is effectively an active filter to clean up the harmonics.
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