applying KVL to semiconductor circuits

Discussion in 'General Electronics Chat' started by uzair, Jan 4, 2008.

  1. hgmjr

    Retired Moderator

    Jan 28, 2005
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    In the link you are referring to, you will notice that in the models for the transistor that there is a diamond shaped symbol in the collector loop. This symbol represents a current controlled current source. As you may already know, the collector current in a BJT transistor is related to the base current by the dimensionless factor referred to as beta. This current controlled current source is included in the model to account for that relationship.

    hgmjr
     
  2. uzair

    Thread Starter Active Member

    Dec 26, 2007
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    If we put a simple battery symbol instead of the current controlled current source's diamond shaped symbol, is there any problem?
     
  3. hgmjr

    Retired Moderator

    Jan 28, 2005
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    The substitution of a battery in place of the current-controlled current-source upsets the integrity of the transistor model.

    hgmjr
     
  4. uzair

    Thread Starter Active Member

    Dec 26, 2007
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    Do upsetting the "integrity" of model means you are going to the wrog path? Obviously going to wrong path means you are going to find fish instead of voltage.
     
  5. hgmjr

    Retired Moderator

    Jan 28, 2005
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    Yes, you would be headed down the wrong path if you substitute a battery in place of the current-controlled current-source.

    You will not find fish but you will get the wrong answer.

    hgmjr
     
  6. uzair

    Thread Starter Active Member

    Dec 26, 2007
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    In the link you have given me it is said that:-
    "We will assign a positive sign to a term that refers to
    a reference voltage drop, and a negative sign to a term that refers
    to a reference voltage rise."
    But the method which i learned says that we assign positive signs where there are voltage rises and vice versa. What about it?
     
  7. hgmjr

    Retired Moderator

    Jan 28, 2005
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  8. uzair

    Thread Starter Active Member

    Dec 26, 2007
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    Thanks i am gonna chenk it and then disturbing everyone very soon.
     
  9. uzair

    Thread Starter Active Member

    Dec 26, 2007
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    [​IMG][/URL][/IMG]

    I have inserted an image which shows wheatstone bridge solved through KVL with my method. Please can anybody tell whether is it right or wrong. If it is wrong, then why?
     
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