output stage of bjt ampl

Discussion in 'The Projects Forum' started by eleceng16, Apr 2, 2012.

  1. eleceng16

    Thread Starter New Member

    Mar 26, 2012
    6
    0
    Hi,

    Could anyone give us tips as to how we should tackle the dc and ac anlaysis of this circuit in order to be able to make further improvements (to minimise clipping)?

    Thanks in advance:)
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,343
    Hello,

    There are a couple of things that can be improved.
    You have 1K resistors in teh emittors of the output transistors.
    With that value you will hardly gat any output, lower that value.
    Also use 4 diodes in the input setup to avoid cross-over distortion, as you have 4 X a BE-transistors transition in it.

    Bertus
     
  3. eleceng16

    Thread Starter New Member

    Mar 26, 2012
    6
    0
    I did as you said. I am giving it an input sine wave peak 10v but the output has a peak of approximately 8v ... is there any way to improve on this?
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,086
    3,024
    What value did you use to replace the 1K resistors? Your current is limited by those and the R15 and R16.
     
  5. DigitalReaper

    Member

    Aug 7, 2010
    70
    2
    Your amplifier has no voltage gain stage, you need to add one between your signal source and the amplifier input if you want more than 8v peak output.

    I'm assuming this is an audio amp given the 8 ohm load. They normally expect something around 1v in. You should lower your signal source to 1v peak and set the gain of your voltage stage to be somewhere around 10 to 15.
     
  6. #12

    Expert

    Nov 30, 2010
    16,247
    6,744
    Either that or turn your sine wave generator up to 32 volts peak.

    It doesn't go that high?

    Then you'll need a voltage gain stage like Reaper said.
     
  7. eleceng16

    Thread Starter New Member

    Mar 26, 2012
    6
    0
    We added a cascaded system with 2 common emitter stages in order to get the voltage gain... the problem is that we get a clipped amplified signal ... how can we minimise the clipping??
     
  8. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Each time you modify your circuit, you should post the modified schematic and parts values or NOBODY knows what you are talking about.

    There are thousands of good audio amplifier circuits on the internet that work perfectly.
    Most are almost the same. Yours is very different.
     
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