Transistor circuit help..

Thread Starter

NiCeBoY

Joined Aug 20, 2008
59
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..
 

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S_lannan

Joined Jun 20, 2007
247
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...
 

Thread Starter

NiCeBoY

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

S_lannan

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