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PUSH PULL AMPLIFIER (MOSFET) HELP NEEDED

  • Thread starter Google Vasiliou
  • Start date
G

Google Vasiliou

Jan 1, 1970
0
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 : [email protected]
 
A

Activ8

Jan 1, 1970
0
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 .
So what's your question?

WHy crosspost to repair if the thing isn't even built?
 
J

jakdedert

Jan 1, 1970
0
Google said:
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 .
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
 
K

Ken Weitzel

Jan 1, 1970
0
Google said:
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 : [email protected]

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
 
R

Rich Grise

Jan 1, 1970
0
Ken Weitzel said:
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
Somebody should give him Terry's barking dog circuit with
MOSFETs drawn in for the outputs. >:->

Rich
 
W

Walter Harley

Jan 1, 1970
0
Google Vasiliou said:
Dear All

I need your help on the following issue.

I have to construct a Class AB - push pull amplifier with MOSFET
Amplifier [...]


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_
 
: 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 : [email protected]

Trying posting to the forum at

www.diyaudio.com

They have a very active solid state amplifier design forum there.
 
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 : [email protected]

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
 
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
 
J

Jim Thompson

Jan 1, 1970
0
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
[snip]

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

...Jim Thompson
 
P

Paul Burridge

Jan 1, 1970
0
So what's your question?

"Can you design it for me?"
No harm in asking, I suppose. But the best grades are honestly earned.
 
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