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Electric circuit how to check linearity

  1. Nov 9, 2012 #1
    Hi all,

    I found the following equations for the electric circuit shown
    Vc(t) = - 1/(R2*C) * Vc(t) – 1/C * i(t) --------------------1
    Vt(t) = Vc(t) – R1*i(t) ------------------------------------ 2

    I have the following questions
    1.The first equation should be dVc(t)/dt = -1/(R2*C) * Vc(t) – 1/C * i(t) . Am I correct on this?
    2.The discrete time equations are given in the documents as
    Vc,k+1 = exp(-T/(R2*C)Vc,k – R2 * (1 – exp(-T/R2*C)*ik --------------- 3
    Vt,k = Vc,k – R1*ik; ------------------------------------------------------------- 4

    I can understand the 4th equation, but I cannot understand the 3 equation, could someone guide me how to do this conversion from continuous to discrete.
    What is the “T” that is used?

    3.Is this system linear? From little understanding I have, when an exponent is involved generally it is nonlinear. What is the methodology I should adopt to check whether a system is linear or nonlinear?

    thanks in advance,

    Attached Files:

  2. jcsd
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