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Homework Help: Simple Transistor Problem

  1. Apr 1, 2007 #1

    I'm having a bit of trouble understanding how exactly to analyze a transistor in a simple circuit... Specifically when finding the collector to emitter voltage, Vce.

    I've gotta be looking at this incorrectly. Below is the question and the solution. My professor worked out the part that I circled as "their" solution, and I circled what I did.

    Could someone explain what I'm doing wrong?

    The only equation I needed for this was:

    http://synthdriven.com/images/deletable/EEN305%20-%2001.jpg [Broken]
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Apr 1, 2007 #2
    nevermind. I'm a complete retard. I Vce should be:


    But I am still a bit confused about how my professor derived his equation. That looks like a good equation for Vc, not Vce... Atleast to me.

    Could someone explain this to me?
  4. Apr 1, 2007 #3


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    Since the emitter is grounded, Ve is the same as Vce.
  5. Apr 2, 2007 #4


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    Oops, typo, I meant Vc same as Vce.
  6. Apr 14, 2007 #5
    your professor calculated Vc for 6 Volts right? now walk backwards through the source to the emitter to get VCE.

    So +6V - 10V = -4V, so VCE has to be 4V.

    Or walk the other way from emitter to collector through the source. +10V-6V=4 Volts.

    VBE which is 0.7 volts plays no role here. in your calculation you say Vc is 3.3V which is NOT correct! it is 6V because RC(2kohm) *Ic(3mA) = 6V!

    hope that helps.
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