Stumped on another BJt problem

Discussion in 'Homework Help' started by Joe24, Sep 16, 2007.

  1. Joe24

    Thread Starter Active Member

    May 18, 2007
    Hello all,

    Given the circuit attached, which will used as a constant current source, I need to find a value of Re that will give I = 2mA.

    I am very weak when it comes to BJT amplifiers. So what I did was I used MULTISIM to try and find a value of Re that will satisfy this problem. The value for Re from the simulator was 1.6K ohms.

    Now I'm not sure if this is correct, but if so, how can I prove this mathematically??
  2. hgmjr

    Retired Moderator

    Jan 28, 2005
    1.6K is not the value I computed.

    Most likely the transistor you selected from the Multisim model library did not have the same parameters as those given in the problem
    Since the problem provides the value for alpha of the transistor then you have enough information to calculate the emitter current and the base current.

    You could begin by calculating these two currents. Post you calculations for these two values and then once you have them we can proceed to the next step.