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-   -   MOSFET power follower project (http://www.diyaudio.com/forums/solid-state/11675-mosfet-power-follower-project.html)

Ilianh 26th February 2003 05:20 PM

MOSFET power follower project
 
Hi,
Anyone ever did this project?

Any feedback would be highly appreciated.


I can't seem to find those irf350 anywhere, anyone knows any replacements?

Could be good for a triamp system

halojoy 26th February 2003 06:12 PM

Re: MOSFET power follower project
 
Quote:

Originally posted by Ilianh
Hi,Anyone ever did this project?

Any feedback would be highly appreciated.
I can't seem to find those irf350 anywhere, anyone knows any replacements?
Could be good for a triamp system

And what MOSFET power follower project
do you mean?
Any special, yours or from some website?

/halo - is not a mind reader ;) - but suspect it has something
to do with a website

Ilianh 26th February 2003 07:56 PM

...

http://sound.westhost.com/project83.htm


bah...

Ilianh 27th February 2003 01:34 AM

anyone knows if one of those would work? they are all hexfet
(and I have many of them at home)
IRF540
IRF640
IRF740
IRF840

they have similar caracteristics as the irfp350 that I need

(I think the irf740 would be the closest one)

Circlotron 27th February 2003 02:14 AM

The lower the current rating of the fet, for the same current the further up the transfer curve you work it where it is more linear, away from the bottom where it is a big curve. The curvy part means distortion. Monster size fets runnning at low current make more distortion.

/Circlotron - doesn't practice what he preaches. :cannotbe:

Ilianh 27th February 2003 02:32 AM

Thx Circlotron for the info.

Well originaly the design is with a IRFP350, wich is
Vdss 400v
Rds 0.3 ohm
Ids 16 amps

the IRF740 is
Vdss 400v
Rds 0.55 ohm
Ids 10 amps

Andypairo 27th February 2003 09:11 AM

Since Vdss is not an issue I'd rather go with 640 or even 540, which have higher current ratings.
Other choiches can be IRFP150, 240, 250, etc, commonly used in similar projects (the former is used in Ciuffoli's Power Follower).

Cheers

Andrea

Ilianh 28th February 2003 01:30 AM

Anyone has any ideas how much power can Ciuffoli's Power Follower output on 8 ohm?
and ayone knows how good are power followers of this kind when the output impedance is 4 or 6 ohm?

argo 28th February 2003 08:52 AM

2 Attachment(s)
Quote:

Originally posted by Ilianh
Anyone has any ideas how much power can Ciuffoli's Power Follower output on 8 ohm?
and ayone knows how good are power followers of this kind when the output impedance is 4 or 6 ohm?

It will depend from rail voltage and bias current.
It will work well into 4 or 6 ohm but you need to feed more current accordingly.

Here is an approximate calculation for different loads

Jay 28th February 2003 06:26 PM

Power follower type has a low distortion figure. Anyhow, many high-end builders do not appreciate this type of amplifier. The reason is that the overall sound is “dull”. An argumentation to defend this design might be (from my opinion) that this amplifier doesn’t color the sound. It just “passes” the signal from the source. So, you must be very careful in choosing your pre-amp. I guest a bipolar design like Bride Of DOZ will do a great job.


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