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
    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
  3. Steel


    Oct 27, 2004
    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.