IRFP240/IRFP9240 Power amp

[JojoD818]

Hi guys,

I have some IRFP240/IRFP9240 leftovers from an F1 project, I was hoping I can build a simple class ab amp out of a single pair. Power output is not an issue as long as it sounds good. Any schematics would be appreciated.

Thanks!

JojoD

[d3imlay]

About 15 years ago I found a 30 watt amp in an IR mosfet book. I built up a prototype and had it fitted into a Dyna 120 chassis. I let a friend borrow it and he said it was the quietest amp he'd ever heard. I'll see if I can dig out all of the old docs. I had gerber files for the board at one time.

[djk]

That IR design was horrible, and so was the board lay-out they published.

[Zen Mod]

Originally posted by JojoD818
Hi guys,

I have some IRFP240/IRFP9240 leftovers from an F1 project, I was hoping I can build a simple class ab amp out of a single pair. Power output is not an issue as long as it sounds good. Any schematics would be appreciated.

Thanks!

JojoD

pass forum-Babelfish pcbs thread-look for Oly's little amp schematic;
doable with simple jfets on input,too-not necessary with scarce 2sj109 and 2sk389

[luixssj3]

I build this and it work...

If you build one too let me know your opinion...

[edl]

Originally posted by JojoD818
Hi guys,

I have some IRFP240/IRFP9240 leftovers from an F1 project, I was hoping I can build a simple class ab amp out of a single pair. Power output is not an issue as long as it sounds good. Any schematics would be appreciated.

Thanks!

JojoD

Check this out:
Holton's amp pcb needed

[jmateus]

This looks simple, I'm in the process of building it.

http://users.swing.be/edwinpaij/ampli_mosfet_simple.htm

[MikeB]

Originally posted by jmateus
This looks simple, I'm in the process of building it.

http://users.swing.be/edwinpaij/ampli_mosfet_simple.htm

John read this thread.

Keep a fire extinguisher near when powering it up... (and the following years) Unless you use real lateral audio mosfets.
There is only one thing that keeps that amp from blowing up within seconds: As the bias rises, the voltage supply falls and reduces bias and might find that way a "stable" bias... A regulated supply would ensure blow up.
John, if you're not too far in constructing, add at least a vbe/vgs multiplier instead of p2.

There should be a law against publishing such schematics.

Mike

[sivan_and]

djk wrote:

That IR design was horrible, and so was the board lay-out they published.

That was true....Me too had a bad experience...I used IFR530/9530

[lineup]

Originally posted by jmateus
This looks simple, I'm in the process of building it.

http://users.swing.be/edwinpaij/ampli_mosfet_simple.htm

Hello JMateues
what transistors you use?
T7 = IRFP240, 2SK1530, 2SJ162, BUZ900DP, BUZ901DP (attention au brochage différent - take care for pin layout : GDS GSD)
T8 = IRFP9240, 2SJ201, 2SK1058, BUZ905DP, BUZ906DP (attention au brochage différent - take care for pin layout : GDS GSD)

http://users.swing.be/edwinpaij/imag...lisimpleV2.gif
I ask, because that amplifier has only resistors to set idle currents.
You have had any thought about adding a simple VBE-multiplier instead to sense the temperature?
It is not very difficult.

Sometimes too simple can be bad or even disaster .....
Other times simple is better than complicated.


Regards
lineup
Likes them Laterals: BUZ900-BUZ901-BUZ905-BUZ906
like used in AussieAmplifiers Antony Holton designs ....