Need ALOT of help with amps

Discussion in 'General Electronics Chat' started by Amplifier, Dec 12, 2004.

  1. Amplifier

    Thread Starter New Member

    Oct 18, 2004
    5
    0
    I have a weird feeling that these questions are unanswerable:


    Compare linar to logarithmic
    For this question I wrote that a logarithm is an exponent to which a standard number is raised to produce a given number. Then I explained the base of natural and common logs. Then to explain linear I described it as something that is uniform, or the same.

    Why are amplifier gains commonly given in decibels? State 2 reasons
    I explained that it was becuase of the dBm and dBk standards, and the fact that you can show loss easily.;

    Coupling caps must have a reactance of less than 1/10th of the input impedance of the amplifier. Would this be for the uppermost, average, or lowest frequency? Why?
    For this I wrote that it should be for all, shouldnt it be?

    Why does the common emitter amp have a 180 phase shift?
    I had zero clue why this happens.

    My teacher claims that he told us this, but I have NO evidence of it in my notes. Any help here?
     
  2. Amplifier

    Thread Starter New Member

    Oct 18, 2004
    5
    0
  3. Steel

    Member

    Oct 27, 2004
    25
    0
    For the common emitter question, it does have a 180 degree phase shift.

    When an AC signal passes through the transistor, at the emitter, it will show a 180 deg. shift. When measured at the collector, the phase will be at it's normal phase.

    This specific reason is why the darlington pair was created.

    It is a sneaky question, and believe it or not, it has been used during interviews.
     
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