200 Watt Lateral Mosfet Amplifier and irfp240/9240

tino96 · 14th April 2003, 04:01 PM

Is possible to change in the 200 Watt Lateral Mosfet Amplifier the output device 2sj 352 and 2sk2221 with irfp240/9240?

If yes, how to do?
p.s. excuse my poor english
bye

JBL · 14th April 2003, 04:24 PM

Nop.

The amp will probably explode or somthing similar.

Nelson Pass · 14th April 2003, 04:28 PM

Depends on the amp. The IR parts will have higher transconductance (which is why I prefer them) and different Vgs values. Without a doubt you will have to rebias the circuit for the new Vgs figure.

tino96 · 14th April 2003, 04:40 PM

the amp is the symmetrical amplifier (designed by Anthony Holton) http://www.aussieamplifiers.com/symmetric.htm
it's possible?

Christer · 14th April 2003, 05:45 PM

I couldn't find any datasheets for IRF240/9240 (searching the
web suggested they are obsolete) but the general answer
would be no, you can probably not use them. Lateral MOSFETs
start to have a negative temp. coefficient already at rather
small Id, so usually no temp. compensation of the bias is
necessary, and indeed Holton's amp follows this practice.
Although I don't know about the IRF240/9240, most, if not
all, non-lateral MOSFETs have a positive temp. coefficient up
to quite high values of Id, several Ampéres, so I would think
they need temp. compensation of the bias.

Perhaps Nelson, or someone else, can give a good reason why
it might work anyway, but the safe general recommendation
would be not to try it.

Andypairo · 14th April 2003, 06:23 PM

In the description of the symmetric amplifier is clearly stated that IRF devices are suitable; for the lateral mosfet I don't think so.

Cheers

Andrea

megajocke · 14th April 2003, 06:37 PM

I found a datasheet for IRF240:
http://circuit.codns.com/data/DataSheet/FET/IRF240.PDF

Hehe... the temerature coefficient doesn't become negative before 11 amps...

tino96: Is it the Symmetric amplifier or the Lateral amplifier you are talking about?

The symmetric amplifier uses a Vbe multiplier, and maybe mounting that together with the transistors would be enough to compensate it... but the other one uses just a pot, and that is probably bad. Another thing is the gate-source voltage of the lateral mosfets are much lower. around 0.5V at 100ma for the lateral mosfets and around 4V for the other one...

HighTec · 14th April 2003, 08:00 PM

Hi guys.

We are talking about IRFP240/IRFP9240!They are not similar with IRF240!And they can't be a replacement for the lateral mosfets.
Regards.

megajocke · 14th April 2003, 09:28 PM

Ooops

I read the number Christer wrote and didn't check what the OP had written.

IRFP240:
http://www.fairchildsemi.com/ds/IR/IRFP240.pdf

thylantyr · 14th April 2003, 09:55 PM

Build the holton AV800 instead..

14th April 2003, 04:01 PM	#1
tino96 diyAudio Member Join Date: Mar 2003 Location: .	200 Watt Lateral Mosfet Amplifier and irfp240/9240 Is possible to change in the 200 Watt Lateral Mosfet Amplifier the output device 2sj 352 and 2sk2221 with irfp240/9240? If yes, how to do? p.s. excuse my poor english bye

14th April 2003, 04:24 PM	#2
JBL diyAudio Member Join Date: Aug 2001 Location: Canada, N.-B.	Nop. The amp will probably explode or somthing similar. __________________ Jonathan Blanchard (J.Bl.) ---Nothing is impossible---

14th April 2003, 08:00 PM	#8
HighTec diyAudio Member Join Date: Mar 2003 Location: Sibenik, Croatia	IRFP240??? Hi guys. We are talking about IRFP240/IRFP9240!They are not similar with IRF240!And they can't be a replacement for the lateral mosfets. Regards.

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14th April 2003, 04:28 PM	#3
Nelson Pass The one and only Join Date: Mar 2001	Depends on the amp. The IR parts will have higher transconductance (which is why I prefer them) and different Vgs values. Without a doubt you will have to rebias the circuit for the new Vgs figure.

14th April 2003, 04:40 PM	#4
tino96 diyAudio Member Join Date: Mar 2003 Location: .	the amp is the symmetrical amplifier (designed by Anthony Holton) http://www.aussieamplifiers.com/symmetric.htm it's possible?

14th April 2003, 05:45 PM	#5
Christer diyAudio Member Join Date: Sep 2002 Location: Sweden	I couldn't find any datasheets for IRF240/9240 (searching the web suggested they are obsolete) but the general answer would be no, you can probably not use them. Lateral MOSFETs start to have a negative temp. coefficient already at rather small Id, so usually no temp. compensation of the bias is necessary, and indeed Holton's amp follows this practice. Although I don't know about the IRF240/9240, most, if not all, non-lateral MOSFETs have a positive temp. coefficient up to quite high values of Id, several Ampéres, so I would think they need temp. compensation of the bias. Perhaps Nelson, or someone else, can give a good reason why it might work anyway, but the safe general recommendation would be not to try it.

14th April 2003, 06:23 PM	#6
Andypairo diyAudio Member Join Date: Sep 2002 Location: near Milano , Italy	In the description of the symmetric amplifier is clearly stated that IRF devices are suitable; for the lateral mosfet I don't think so. Cheers Andrea

14th April 2003, 06:37 PM	#7
megajocke diyAudio Member Join Date: Jan 2003 Location: Solna	I found a datasheet for IRF240: http://circuit.codns.com/data/DataSheet/FET/IRF240.PDF Hehe... the temerature coefficient doesn't become negative before 11 amps... tino96: Is it the Symmetric amplifier or the Lateral amplifier you are talking about? The symmetric amplifier uses a Vbe multiplier, and maybe mounting that together with the transistors would be enough to compensate it... but the other one uses just a pot, and that is probably bad. Another thing is the gate-source voltage of the lateral mosfets are much lower. around 0.5V at 100ma for the lateral mosfets and around 4V for the other one...

14th April 2003, 09:28 PM	#9
megajocke diyAudio Member Join Date: Jan 2003 Location: Solna	Ooops I read the number Christer wrote and didn't check what the OP had written. IRFP240: http://www.fairchildsemi.com/ds/IR/IRFP240.pdf

14th April 2003, 09:55 PM	#10
thylantyr diyAudio Member Join Date: Feb 2001 Location: Mars	Build the holton AV800 instead..

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