extremely low load resistance on npn transistor!!!

Discussion in 'Homework Help' started by toze, Nov 26, 2008.

  1. toze

    Thread Starter New Member

    Nov 26, 2008
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    Greetings to you all!
    I have an asignment for school and I am stuck!!I have an npn transistor with the load connected on e. The question is what will happen if the load resistance becomes 10 times lower, appart from the obvious, that I 'll have more current on the load!!

    thanks in advance!
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    Vce will decrease, Ib will increase or the transistor may blow up due to overheating.
     
  3. hobbyist

    Distinguished Member

    Aug 10, 2008
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    My only guess would be the voltage across the load would decrease as the emitter is being brought closer to ground.
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    If the transistor has enough current gain to supply this extra current the voltage will be approximately the same as before.
    It's an emitter follower circuit, isn't it?
     
  5. hobbyist

    Distinguished Member

    Aug 10, 2008
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    yeh your absolutely right I just simulated it, and now that I look at it it does make sense, the base voltage remains the same due to the base resistor divider, so as long as the base current doesn't upset the voltage divider then the base voltage minus the Vbe, would be the voltage across the load, so it really depends on how much the base voltage remains stable, so if the load is not too heavy to cause the base voltage to change significantly then like you said the emitter will follow the base voltage. emitter follower.
    I learned a lot about this thankyou...Mik3
     
    Last edited: Nov 26, 2008
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