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A diode with a resistor in parallel and in series.

  1. May 8, 2012 #1
    I have a diode with a resistor in parallel(R2), but also diode resistor circuit has a resistor in series with it(R1). I have uploaded a drawing as well but I think it takes a bit of time for them to be authorised.
    The values of the circuit are
    Vs = 20v
    R1 = 3kΩ
    R2 = 470Ω
    Diode = Has a Volt drop of 2v

    I've found the formula Vo-Vd/Rl = I for a diode in series in a resistor but am not sure how this relates if the diode also has resistor in parallel with it. I'm guessing from what I've read that the diode does not have a resistance as such but only 'consumes' 2v, so can I use 18v along with the resistance in the remainder of the circuit to calculate It ? Or am I heading down the wrong path entirely. This is my second night on this question so could really do with some help. Thankyou
     

    Attached Files:

  2. jcsd
  3. May 9, 2012 #2

    NascentOxygen

    User Avatar

    Staff: Mentor

    My .doc viewer isn't working, but I think I can see the circuit. That would be a zener diode, and, yes, it leaves 18V across R1.

    Knowing the voltage across R2, you can calculate the current through R2.
     
  4. May 9, 2012 #3
    Thank you so much. I think I was mis understanding that the voltage drop stated was the same as the voltage shown across, when that twigged today I got it, what a feeling :) Thank you for your help and time :)
     
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