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[HELP] Diode Question

  1. Feb 15, 2009 #1
    1. The problem statement, all variables and given/known data

    Design a “smart” branch with resistors and a diode pair such that the branch resistance drops if the voltage applied on the two ends of the branch is too high, and vice versa, (i.e., the branch resistance increases if the voltage applied on the two ends of the branch is too low).

    2. Relevant equations

    3. The attempt at a solution
    Could Anyone explain to me what is this question asking me to do? Or like any hints as to how should i solve this type of question?
  2. jcsd
  3. Feb 16, 2009 #2


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    Staff: Mentor

    I agree this is kind of an obtuse question. They are being quite unhelpful in using inexact terms likje "too high" and "too low". Do they give any better definition of the voltage levels in the actual problem statement?

    If you can interpret "too high/low" as being around a diode drop, then it's straightforward how to do the first part, but less obvious about increasing the branch resistance (unless negative voltages can be used as well).

    If they intend a little higher than diode drop voltages, you may be able to use resistor voltage dividers...

    If they intend a lot higher than a diode forward drop, then maybe they will let you use Zener diodes? Or at least diodes with a known reverse breakdown voltage?
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