Common emitter amplifier design

Discussion in 'General Electronics Chat' started by Exjay, Sep 6, 2017.

  1. Exjay

    Thread Starter Member

    Nov 19, 2015
    39
    1
    I was trying to design an audio amplifier using the common emitter configuration. So I surfed the web for circuit. My calculations gave me an R1, R2,Rc and Re are respectively 4.7kohms, 1kohms, 56kohms and 12kohms. I don't know how to calculate the values of the coupling and bypass capacitor for the range of audio frequency. Please easy on me as am a beginner in electronics

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  2. BobTPH

    Senior Member

    Jun 5, 2013
    1,182
    234
    You calculate the capacitors based on the the load (for the output capacitor) and the input impedance for the input capacitor. You want an RC filter with a corner lower than the lowest frequency you want to amplify. If you did the calculations, there should be a formula for the input impedance, which will depend on the biasing resistors, the emitter resistor and the beta of the transistor.

    I cannot read your posted photo, when I click it, I get a very unreadable gran on gray enlargement.

    Bob
     
  3. Exjay

    Thread Starter Member

    Nov 19, 2015
    39
    1
    audio frequency are between 20Hz-20kHz, is 20Hz my lower frequency? Again how will I calculate the output capacitor
     
  4. dl324

    AAC Fanatic!

    Mar 30, 2015
    6,975
    1,611
    You want the capacitor impedance at 20Hz to be significantly smaller than the load impedance.
     
  5. Exjay

    Thread Starter Member

    Nov 19, 2015
    39
    1
    This is my new modification
     
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