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Homework Help: Half wave rectifier Ripple Voltage

  1. Jun 5, 2010 #1
    1. The problem statement, all variables and given/known data

    A capacitor of capacitance C is connected in paralell with a resistor of R ohms impedance. Calculate the size of the peak to peak voltage of the ripple produced relative to the peak output voltage Vp.

    2. Relevant equations

    Q=CV
    dQ/dt = I
    V=IR
    Vc=Vpe-t/RC (am i allowed to use this in an AC circuit?)
    or Vc=-jI/R[itex]\omega[/itex]C

    V = Vpcos([itex]\omega[/itex]t)

    3. The attempt at a solution

    Voltage drop across the resistor is just:

    V = Vpcos([itex]\omega[/itex]t)

    Voltage drop across the capacitor can be aproximated to:

    Vc=Vp(1-e-t/RC)

    The alteration to the equation in 2 is to ensure the capacitor voltage is 0 at t=0.

    At t=0

    VR - Vc = Vp

    at t=T/2 or at 1/f

    VR - Vc = Vpe-1/fRC

    The ripple voltage will be the differance between these two:

    VRipple= Vp(1-e-/fRC)
     
    Last edited by a moderator: Feb 7, 2016
  2. jcsd
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