Connect with us

PUSH PULL AMPLIFIER (MOSFET) HELP NEEDED

Discussion in 'Electronic Basics' started by Google Vasiliou, Jun 4, 2004.

Scroll to continue with content
  1. Dear All

    I need your help on the following issue.

    I have to construct a Class AB - push pull amplifier with MOSFET
    Amplifier should be able to provide 21Watt output power (10.5
    Watt RMS) at 8 ohm load (i.e speaker) .
    The circuit suppose to be able to amplify input signal from 1 Vrms at
    a range of 10 Hz to 40 KHz .

    Requirements
    1) Vdc should not exceed 50 Volts
    2) Dc Current not to exceed 2 Amperes.
    3) Construction of Amplifier should be with MOSFET , even if we can find
    easier ways!


    Your opinion would be reall help for me .

    Regards

    George Vasiliou
    GREECE
    email :
     
  2. Activ8

    Activ8 Guest

    So what's your question?

    WHy crosspost to repair if the thing isn't even built?
     
  3. jakdedert

    jakdedert Guest

    This sounds like a school assignment...why would it 'have to be' Class AB,
    MOSFET, and 21 watts? There are lots of ways to make a 20 watt amp....

    jak
     
  4. Ken Weitzel

    Ken Weitzel Guest

    Hi George...

    You have to do your own homework, or else you learn
    nothing, and your mark means nothing.

    Study hard, work hard, do it all honestly with
    your very best effort, and you will succeed
    honorably.

    Take care, and good luck with your assignment.

    Ken
     
  5. Rich Grise

    Rich Grise Guest

    Somebody should give him Terry's barking dog circuit with
    MOSFETs drawn in for the outputs. >:->

    Rich
     

  6. Some references that might help you:

    Horowitz and Hill's _Art of Electronics_, 2ed.
    Randy Slone's _High-Power Audio Amplifier Construction Manual_
    Douglas Self's _Audio Power Amplifer Design Handbook_
     
  7. Guest

    : Dear All

    : I need your help on the following issue.

    : I have to construct a Class AB - push pull amplifier with MOSFET
    : Amplifier should be able to provide 21Watt output power (10.5
    : Watt RMS) at 8 ohm load (i.e speaker) .
    : The circuit suppose to be able to amplify input signal from 1 Vrms at
    : a range of 10 Hz to 40 KHz .

    : Requirements
    : 1) Vdc should not exceed 50 Volts
    : 2) Dc Current not to exceed 2 Amperes.
    : 3) Construction of Amplifier should be with MOSFET , even if we can find
    : easier ways!


    : Your opinion would be reall help for me .

    : Regards

    : George Vasiliou
    : GREECE
    : email :

    Trying posting to the forum at

    www.diyaudio.com

    They have a very active solid state amplifier design forum there.
     
  8. Guest

    Yassoo! George!

    There is a "standard circuit" for this that you should copy. Your work
    will then be to calculate the currents and fiddle with the values so
    there is no original design involved, just a familiarisation.

    As the other poster said, look at the Horrorwitz and Hill to see how
    the differential input stage works etc the copy an existing design
    (there is no shame in this) and rework the values.

    When it oscillates, take the energy of the oscillating frequency out
    of the loop via the network to ground:-

    (part of the feedback loop)
    to input------/\/\/\/------\/\/\/\/\----from OP
    |
    |
    -------
    -------
    |
    |
    \
    /
    \
    /
    \
    |
    |
    -----
    ---
    -


    Cheers
    Robin
     
  9. Guest

    Hello there,
    Pushpull amplifiers can be with transformer or without them. I imagine you are
    going for a transformerless one, which will be a cheaper solution too,
    however, harder to design.
    First you gotta determine the voltage. the formula is P=v^2/8*R It means on 8
    ohm loudspeaker and 10,5 watt rms V must be almost 30 Volts due to some
    voltage drop in current in MOSFETs and current sense resistors add a few
    voltages to this .. 32 volts must be OK.
    I hope this can help, if it is useful then leave a message so I go on with
    that.
    Good luck,
    Dario
     
  10. Jim Thompson

    Jim Thompson Guest

    [snip]

    The correct equation is P = (Vp-p)^2/(8*R) or P = (Vrms)^2/R

    ...Jim Thompson
     
  11. "Can you design it for me?"
    No harm in asking, I suppose. But the best grades are honestly earned.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-