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Homework Help: Another transistor problem

  1. Jun 30, 2010 #1
    [PLAIN]http://img256.imageshack.us/img256/2164/transistor.jpg [Broken]

    i should find Re so that transistor works in saturation region

    also i should find Ib in saturation region

    Rc=2kΩ , R1=2kΩ , EB=5V, Vcc=10V, V1=3V, β=100

    im really confused with R1 and V1 i dont know what is their function

    i know that in saturation region Vce = 0

    also from the diagram i can see that

    Eb - 0.7 = Vre so Vre = 4.3 Volts

    Ie = Vre/Re

    if we assume that Ie = Ic


    Ic = Vre/Re

    Ic is Vcc/Rc = 10/2000 = 5mA

    so Re should be Vre/5mA = 4.3/5*10^-3 = 0.86 KΩ

    but does this Re stand for saturation region?
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Jul 1, 2010 #2
    Your calculation for Ie doesnt take into account current flowing due to Vcc or V1 in the resistor Re. Use Kirchoff's laws.
  4. Jul 1, 2010 #3
    we have

    Eb - 0.7 = Ic1*Re we find Ic1 from Eb

    Vcc - Ic(Rc+Re) - Vce = 0
    V1 - Ic(R1+Re) - Vce = 0

    we find Vce from these two statements and Ic which I will have to add Ic1?

    and how can this help me solve the problem?
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