opamp always saturate, help

Discussion in 'Homework Help' started by Santa klaus, Feb 3, 2015.

  1. Santa klaus

    Thread Starter New Member

    Nov 16, 2014
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    Last edited: Feb 3, 2015
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    I see no saturation. U1 swings from +1.5V to -1.5V.

    U2 is sitting at 0V

    The emitter follower is following... (It wouldn't if it had a load because it is not biased right).
     
  3. Santa klaus

    Thread Starter New Member

    Nov 16, 2014
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    Could you check the output current. it should be sine wave (maybe with crossover distortion), i currently get a square signal.
    Also, can i leave the follower biased this way?
     
    Last edited: Feb 4, 2015
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Are you asking about the audio.asc file you posted, or something else?
     
  5. crutschow

    Expert

    Mar 14, 2008
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    Your audio.asc circuit has only a passing resemblance to the circuit you referenced.
    Why don't you simulate the referenced circuit?
     
  6. Santa klaus

    Thread Starter New Member

    Nov 16, 2014
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    Here is the final circuit. I still get the same results.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    U2 has no input resistor so it is acting as a comparator. Add a 2kΩ resistor in series with the output of U1.
    If you look at the referenced circuit, it uses a pot for R2 which provides the resistance you are missing.
     
  8. Santa klaus

    Thread Starter New Member

    Nov 16, 2014
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    Awesome, it solves the problem . I have an amplified sine wave but there some little deformation around 0
    , it
     
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