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Power Push-Pull Amp ( class AB )

  1. Dec 23, 2012 #1
    Hi :shy:

    I'm a new member here

    for a long time I'm looking for a help in my project Power Push-Pull Amp ( class AB ) :cry:

    Can anyone help me with circuit diagram in Multisim for class AB or anything :biggrin:
     
    Last edited by a moderator: Dec 29, 2012
  2. jcsd
  3. Dec 23, 2012 #2
    What exactly do you have a problem with?
     
  4. Dec 23, 2012 #3
    I had a circuit it is work in Multisim, but when I build it a real one

    It doesn't work !!!
     
  5. Dec 23, 2012 #4
    Show us full circuit diagram.
     
  6. Dec 23, 2012 #5
    Hi , well from my experience I can say that Multisim isn't always so accurate on some circuits when testing them.As real life is close to the book but not by the book always.
    i just built some multivibrators and in real life with the exact same parts and circuit they behave different than in simulation.
    You should show us the circuit to tell you more about it but basically any amplifier should be built stage by stage , you build one stage at a time then check it test it and if it works then build the next one.
    I built an AB class push-pull amp too and firstly I had some problems but then it was just error correction and some faulty parts and everything went on.

    Also it would be great for you to tell us not only the circuit but from where you got it.Some sources on the internet are not reliable at all and some are there because they put scams on the internet just for fun so that someone who isn't experienced enough would have problems with building one.
     
  7. Dec 26, 2012 #6
    Hi , actually it is a circuit for ( Electronic Devices (Conventional current version) ) book P368

    IMG-20121226-00207.jpg

    I hope it is clear :uhh:

    First I used as it said in the book (in Multisim) :

    3 Resistors + 3 Diodes + (2 transistor: 2N3904 + 1 transistor: 2N3906 + 2 transistor: BD135 )

    but the wave doesn't amplified, after that I add 1 capacitor in the input and another three Resistors ( R Load in the output ) it amplified.

    in real, I do the same, the output amplified. The problem is I want to see the top half wave and the bottom half wave. I tried to separate the Q1 and Q2 from the circuit and test it, but it doesn't work !! and the same for Q3 and Q4 !!
     
  8. Dec 29, 2012 #7
    You should never built this Push-Pull Amp in the first place.
    First you should add 1 ohm emitter resistor to Push-Pull stage. And use R1 resistor to set 0V at output without input signal .
     
  9. Dec 31, 2012 #8
    I can't imagine people assemble an audio amp from discrete transistors in the 21st century. There are integrated circuits for that.

    We did use discrete transistors when I was a teenager, and I have grey hair now.
     
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