Need help with a diode circuit problem

Discussion in 'Homework Help' started by copper_pipe, Sep 30, 2014.

  1. copper_pipe

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    Sep 30, 2014
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  2. paulktreg

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    Jun 2, 2008
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    Homework?

    (Show us a screenshot of your attempted solution).
     
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  3. copper_pipe

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    Sep 30, 2014
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  4. Jony130

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    Hi, to me your solution is wrong .
    For Vd = 0.7V diode current is equal to
    Id = (4*0.7V + 5*0.7^2) = 2.8 + 2.45 = 5.25mA
    And resistor current
    Ir = (5V - 0.7V)/200Ω = 21.5mA
    So Id is not equal to Ir. and this means that your solution is wrong.
    And the correct answer is Vd ≈ 1.51V because this time
    Id ≈ 4*1.51V + 5*1.51V^2 ≈ 17.4405mA and Ir = (5V - 1.51V)/200Ω ≈ 17.45mA
    And since Id≈Ir we have a correct solution.
    Additional I plot Id vs Vd and load line

    1.PNG
     
    Last edited: Oct 1, 2014
  5. copper_pipe

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    where is the 1.51v coming from?
     
  6. Jony130

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  7. MikeML

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    Or Let LTSpice solve that equation. The B1 behavioral current source has the same I/V behavior as the diode...

    IV.jpg
     
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  8. copper_pipe

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  9. Jony130

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  10. copper_pipe

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    Sep 30, 2014
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    230 V * 1/5 = 46Vrms on the secondary

    Output pk voltage will be 46 * sqrt(2)/pi = 20.70V = DC

    RMS = 20.70V/2= 10.35V

    P = I^2 * R = Vrms^2/R

    P = 10.35^2/10 = 10.71W


    Does this look correct to you guys?
     
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