Wien Bridge Oscillator Problem

Discussion in 'Homework Help' started by Volt, Apr 21, 2010.

  1. Volt

    Thread Starter Member

    Nov 28, 2008
    24
    0
    Hi, I need to design a wien bridge oscillator with a frequency of 20kHz, the values for the resistors and capacitors in the tuned network i've calculated are 500 ohms, and 16nF. However when I simulate this the frequency of the oscillations is 16kHz.

    I don't know why this is, can anyone explain this and help get the right frequency.

    thanks
    :eek:
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Have you taken the input impedance of the amplifier into account?

    Seriously, we need a schematic, there is no way we can even begin to help due to lack of information.
     
  3. Volt

    Thread Starter Member

    Nov 28, 2008
    24
    0
    Hi,

    I'm simulating with an ideal op amp so I suppose the impedance isn't an issue.

    I have attached the schematic, on the frequency selective components:

    R1=R2= 500Ω
    C1=C2=16nF

    I work that out to be:

    1/((2pi)(500Ω)(16nF) ≈ 20 kHz

    but it is only simulating to 16kHz.

    The other component values:

    R3=18.2 kΩ
    R4= 10 kΩ
    R5= 5kΩ


    Thanks
     
  4. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    Is your ideal model actually the 741 model?
     
    Last edited: Apr 21, 2010
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
  6. Volt

    Thread Starter Member

    Nov 28, 2008
    24
    0
    My ideal model is the virtual amplifier on Multisim
     
  7. kingdano

    Member

    Apr 14, 2010
    377
    19
  8. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
  9. kingdano

    Member

    Apr 14, 2010
    377
    19
    cool app note

    i see a useful circuit i can build at work

    an encoder simulator - quadrature oscillator into a schmitt trigger or other sine to square wave converter.

    then i can use that signal to drive fet gates to switch on 12V or 24V to the inputs of our printers.

    i think they need 24V...will check tomorrow.

    might help me prove my knowledge of analog...thank you app notes.
     
Loading...