Why would a circuit not operate exactly as predicted?

Discussion in 'Homework Help' started by murrdpirate, Sep 19, 2011.

  1. murrdpirate

    Thread Starter New Member

    Sep 19, 2011
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    I designed a filter in Pspice and then built it. The built filter operates close to the design, but the dB drop vs frequency isn't quite as steep as it should be and it stops dropping a bit before it should. What would cause this?
     
  2. Jony130

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    Feb 17, 2009
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    Have you take into account (consideration) the tolerance of the component that you used?
     
  3. murrdpirate

    Thread Starter New Member

    Sep 19, 2011
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    Well, sort of. I've varied the resistor and capacitor within Pspice to see the effect of variance (within tolerances). While that has an effect, it's pretty negligible. Although it may account for the slightly less steep slope.

    Here's the AC sweep of my low pass filter. As you can see, it gets a bit haywire after 2000 Hz.

    [​IMG]
     
  4. Jony130

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    What type of a op amp you use?
    And maybe post the hole diagram
     
  5. murrdpirate

    Thread Starter New Member

    Sep 19, 2011
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    Using two LM324 op amps. Whether I get this figured out or not, I do appreciate the effort.
     
  6. Jony130

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  7. murrdpirate

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    Sep 19, 2011
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    That is actually quite helpful. Thanks very much!
     
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