transistor amplifier help!

Discussion in 'Homework Help' started by bajoelkid12, Sep 29, 2009.

  1. bajoelkid12

    Thread Starter New Member

    Sep 29, 2009
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    hey guys..i'm new here..nice to join this forum :)
    could you please help me.
    i have a problem for my homework, what is the difference between DC signal transistor signal amplifier and AC signal transistor amplifier ???

    thanks a bunch :)
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    DC amplifier amplifies DC voltages (and AC if the specifications allow). However, an AC amplifier amplifies only AC voltages.
     
  3. bajoelkid12

    Thread Starter New Member

    Sep 29, 2009
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    thanks a lot mik3
    is there any other difference ???
    in my opinion, DC amplifiers amplifies the currents but AC amplifiers amplifies the voltage, is that correct?
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    No, you are wrong. Both types can amplify voltage or current depending on their design.

    Another difference is that you can easily cascade AC amplifiers without amplifying the bias voltage because of the coupling capacitors. With DC amplifiers cascading is more complicated if you do not want to amplify the bias voltage.
     
  5. bajoelkid12

    Thread Starter New Member

    Sep 29, 2009
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    being more confused..

    transistor will work on DC, right?
    so how can it amplifies the AC ?

    i'm sorry, i know this is a very basic question..
     
  6. mik3

    Senior Member

    Feb 4, 2008
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    By proper biasing of the transistor it can amplify AC signals.
     
  7. hobbyist

    Distinguished Member

    Aug 10, 2008
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    Without the DC (biasing) of the transistor, then the AC cannot be properly amplified, because the proper amplification of an AC signal is really the DC bias of the transistor fluctuating in step with the AC signal coming in.

    Its like in a swimming pool, when the water is completely still, (steady state) ,the water represents the DC bias, and then you move your hand up and down in the water, as your hand moves up and down in the water your hand displaces the water and the water takes on a shape (small wave), in step with the movement of your hand.

    So it could be looked at with a AC signal it displaces ,if you would, the DC (steady state) of the DC current flowing.

    This is NOT what happens electrically but I'm just using this as an analogy .
     
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