Transistor circuit help..

Discussion in 'Homework Help' started by NiCeBoY, Aug 27, 2008.

  1. NiCeBoY

    Thread Starter Active Member

    Aug 20, 2008
    59
    0
    Hello,
    can anyone help me out with these 3 questions please:

    1. Describe what is meant by the term "cutoff" and "saturation" in terms of a load line?
    2. Explain what would limit the peak to peak value of Vo?
    3. Does hFE vary with IC?

    I have attached a picture of this circuit..

    For question 1 and 2 i know the definition of cut off and saturation but not in terms of load line.
    what i know is :

    In the "cutoff" region both the base-emitter and collector-base junction are reversed biased and in the saturation region both the base-emitter and collector base junction are forward biased.

    and for number 2.

    I think for the limit its the output it depends on the input which is 15V..

    Anyway waiting for someone to help..
    thx in advance..
     
  2. S_lannan

    Active Member

    Jun 20, 2007
    247
    2
    In terms of a load line

    In cut off there will be the supply voltage across the transistor and the only current flowing through shall be leakage current (ICBO).

    In saturation there will be very little voltage across the transistor (VCEsat) and maximum current will flow through the transistor.

    Does hfe vary with IC?
    definately!
    check out some datasheets and see how hfe varies.
    transistors are far from perfect but a with a bit of feedback and ingenuity they work great...
     
  3. NiCeBoY

    Thread Starter Active Member

    Aug 20, 2008
    59
    0
    and what about the second question "2. Explain what would limit the peak to peak value of Vo?"
     
  4. S_lannan

    Active Member

    Jun 20, 2007
    247
    2
    you're pretty right about number 2.
    the collecter supply voltage 15v, is what generally limits the peak to peak output swing.
     
  5. NiCeBoY

    Thread Starter Active Member

    Aug 20, 2008
    59
    0
    Thanks a lot for your reply man ;)
     
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