2 Transistor circuit and voltage notations

Discussion in 'Homework Help' started by Liqauttro, May 23, 2015.

  1. Liqauttro

    Thread Starter New Member

    May 23, 2015
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    Hey There
    I have a few questions about the attached circuit picture(it is a solved example from Borow's book) :
    1)Why isn't Vbb mentioned?Is that because of its equality to Vcc?
    2)Why is the alternative circuit true ? Why did the Vcc notation remain in its place and also Why was a Dc source called Vcc added ?

    Thanks in advance for all the helpers
    I will be glad to see your altenraive circuits diagrams since This one isn't really clear for me
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    Look at this marked up/edited diagram, it should make it clear.
     
  3. Liqauttro

    Thread Starter New Member

    May 23, 2015
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    Ok ,thank you for your diagram , it made things clearer although that
    I still don't understand where Vbb notation dissapeared(Is it required ? if not ,so why ?)
    Could you help me with that?
     
  4. ericgibbs

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    Jan 29, 2010
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    hi,
    I do not see a Vbb on your diagram.??

    What would a Vbb notation mean , anyway.?

    E
     
  5. Liqauttro

    Thread Starter New Member

    May 23, 2015
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    Oh sorry ,I probably didn't make myself clear enough
    Ok, Vbb is the voltage seen on the pictures attached
    Now ,Bobrow ,the author of the book uses in its book when sketching
    a diagram of every circuit which includes NPN BJT t, and he simply omitted this notation on this specific diargram
    I wanted to ask you why he did that
     
  6. Liqauttro

    Thread Starter New Member

    May 23, 2015
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    Also ,pay attention that on the second diagram(on the right one) Vbb isn't mentioned explicity ,yet ,it is written in the explaination above it that Vbb=Vcc=10V
     
  7. ericgibbs

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    I would read the two circuits as you do, Vbb is the same value as Vcc .
    The author has renamed Vcc to Vbb.
     
  8. Liqauttro

    Thread Starter New Member

    May 23, 2015
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    Ok, so actually on the first diagram we started with ,you actually say Vbb=Vcc,am I right ? and since
    that Vbb doesn't appear ?
     
  9. ericgibbs

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    Jan 29, 2010
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    In the first circuit the Base bias upper resistor is connected to Vcc, which is typical.

    The author has then reduced the circuit to show Vcc supplying the Base as a separate voltage source, which should be named Vbb driving the base resistors, note that Vbe is the voltage between the Base and Emitter.
     
  10. Liqauttro

    Thread Starter New Member

    May 23, 2015
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    Ok ,understood ,I actually got really confused with his notations
    Now you made it clearer
    Thank you very much for your help ,sir!
     
  11. ericgibbs

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  12. Liqauttro

    Thread Starter New Member

    May 23, 2015
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    Thank you again!,
    Btw, what is the source of this pdf file ? from which book was it taken?
     
  13. ericgibbs

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