Opamp oscillator

Discussion in 'Homework Help' started by xxxyyyba, Nov 22, 2015.

  1. xxxyyyba

    Thread Starter Member

    Aug 7, 2012
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    Here is my task and solution for a)

    ddd.png

    Any suggestion for task b) ?
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    What your thought about this ? Also do you recognize the building blocks?
     
    Last edited: Nov 23, 2015
  3. xxxyyyba

    Thread Starter Member

    Aug 7, 2012
    249
    2
    ddd.png
    When v12(t) reaches in amplitude value of VD+VZ=6.8V, DZ1 will start conducting in forward direction DZ2 will start conducting in reverse direction. While conducting, they will provide constant voltage drop on R, 6.8V.
    That's what I know :)
     
  4. crutschow

    Expert

    Mar 14, 2008
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    The two top circuits are called All-Pass filters, as their ouput phase changes with frequency but the amplitude is constant.
     
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  5. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    At first glance the answer looks obvious. But to by honest the more I think about it, the more confused I get. So I don't know how you can find this output voltage.
     
  6. xxxyyyba

    Thread Starter Member

    Aug 7, 2012
    249
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    Ok.
    This is very strange example I would say :) Even simulation in Multisim show result which I would not expect.
    Thanks anyway.
     
  7. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    I got the attached results in a simulation. There was NO VD in your diagram. I did set an initial charge on the capacitors to kickstart the oscillations. Post your multisim.
     
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  8. xxxyyyba

    Thread Starter Member

    Aug 7, 2012
    249
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    R5 in your schematic should be 10k
    I will post multisim
     
  9. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    I followed your R2 < R3 instruction in b)

    I will change it back to 10 k and rerun the simulation and post the results

    on edit ... added two images ....
     
    Last edited: Nov 24, 2015
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