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Homework Help: Non ideal opamp

  1. Feb 10, 2015 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    I drew the circuit here:
    I'm not sure where to start with this problem.

    Edit: Sorry for using this site for help so much, I just have midterms coming up soon and need to get practise problems solved and I don't have money for a tutor.
    Last edited: Feb 10, 2015
  2. jcsd
  3. Feb 11, 2015 #2


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    My recommendation: Start with your handwritten drawing and apply the existing basic rules for analyzing a network that contains two voltage sources: Superposition.
    This procedure will lead you to the correct result.
    Finally, you can check your result by setting (a) the open-loop gain to infinite, (b) the input resistance to infinite and (c) the output resistance to zero.
    Then, you must arriove at a simple expression that is known from the theory of IDEAL opamp applications.
  4. Feb 11, 2015 #3

    rude man

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    Homework Helper
    Gold Member

    Redraw the circuit with input and output impedances OUTSIDE the op amp. Give the op amp itself a gain of 300,000.
    If you do this right you will wind up with three nodes: vn, vo and vg plus of course the input voltage. vo is the op amp output voltage which will differ from vg since there will be a drop across the 5K output impedance.
    Use standard KVL or sum of currents = 0.
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