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Single Transistor Overall Current Gain

  1. May 28, 2013 #1
    1. The problem statement, all variables and given/known data
    THe problem statement and given solutions are in this thread:


    I do not understand the equation for current gain:

    2. Relevant equations
    Ai = [itex]\alpha[/itex][itex]\frac{R4}{R4 + Ri}[/itex]

    3. The attempt at a solution
    I have pages of work on this, but basically what I know is [itex]\frac{Io}{Ie}[/itex] = [itex]\alpha[/itex]

    then [itex]\frac{Ie}{Ii}[/itex] must equal [itex]\frac{R4}{R4 + Ri}[/itex], I don't see that.
  2. jcsd
  3. May 28, 2013 #2


    User Avatar

    Staff: Mentor

    Why have you started a second thread for your own question?
  4. May 28, 2013 #3
    I started a second thread because I thought I had figured it out. I stated so in that thread, and thus expected no one would reply. I asked another question about this same circuit in a third thread.
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