Which N Or P Power MOSFETs ?...

[bitrex]

On 11/19/2020 3:40 PM, Phil Allison wrote:

bitrex puked more verbal diarrhoea:

==============================
bitrex is completely wrong as usual :

============================

Vertical MOSFETs when used as linear amps have basically all the same
problems BJTs can have, thermal runaway and second breakdown.

** Yeah right - problems that were solved 40 years ago.

Phil\'s behind the times as usual, modern devices like HEXFETs are not
immune (PDF):
https://toshiba.semicon-storage.com/info/docget.jsp?did=63593

** Don\'t ya just love when some know nothing fuckhead like \"bitrex\"\'
chucks a URL at you and says -
\" the proof of my wrong idea is here, go search for it.\"

That is never an *argument* at all and very often, as here, the URL actually contradicts the wrong idea.

Fuck off \" bit brain\" !!!

There are far too may TROLLS like you fucking up the NG.


..... Phil

Tell the OP all about it he\'s the one who wants to build a 140V/18A
power amp as a first project and is asking about what MOSFET to use
instead of reading one of the well-written books or papers on the topic.
Come up with a list of lateral FETs or 30 y/o switching devices that fit
the bill for him, feel free I won\'t stop you.

HEXFET is just a brand name most high transconductance high current
modern switching MOSFETs are celled and have the issues discussed in the
paper.

 

[John Larkin]

On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH

We don\'t know if the OP wants to drive motors or speakers or rail
guns.

 

[piglet]

On 19/11/2020 12:25 pm, Jeff Urban wrote:

Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.

To answer your question: the N-channel MOSFETs are usually operated with
their drain more positive than the source, making the gate more positive
than the source makes them more conductive drain-source, making the gate
negative of the source makes them turn off. A small number are available
as Depletion variety whereby they are already conductive when the gate
is at zero volts (wrt to source) and so you actually need to drive the
gate negative to get them off. The great majority of N-channel mosfets
are Enhancement variety which are already fully off at zero gate volts.
N-channel mosfets are conceptually a little bit like NPN bipolar
transistors (overlooking massive things like gates having no base
current, poorly defined turn-on voltage etc etc etc). N-channel mosfets
are available in the largest range right up to high voltages.

P-channel mosfets are exactly the opposite, the drain is usually
operated negative of the source, driving the gate negative of the source
makes them conductive, at zero or positive gate volts (wrt source) they
are off. They currently exist only as enhancement devices. They are
conceptually a little bit like a PNP bipolar (grossly overlooking all
the huge differences hinted at above). P-channel mosfets tend to need
larger die area to get same on-resistance as a similar N device, are
generally harder to make and so cost more. Really high voltage devices
don\'t exist yet. The variety made is smaller.

All that is explained much better in books like the Art of Electronics
or on zillions of web-pages.

piglet

 

[George Herold]

On Thursday, November 19, 2020 at 4:51:32 PM UTC-5, John Larkin wrote:

On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH
We don\'t know if the OP wants to drive motors or speakers or rail
guns.

Yeah. The load is important. R\'s are easy.
Walking around thinking, I don\'t really like the multi-tapped
G-amp anymore than the two tap A/B amp. (+/-)
When driving weird loads cross-over distortion.. hic-ups is a concern.
I\'m thinking the 3 tap class G thing has three times as many
cross-overs... depending on the amplitude.

So how about a class D amp doing a (relatively) slow power rail.
(say 1 ms)
and a class A amp inside doing the fast stuff. (1 us?)
I\'m thinking single sided.
That wouldn\'t work for a short pulse.

George H.

 

[George Herold]

On Thursday, November 19, 2020 at 5:14:13 PM UTC-5, piglet wrote:

On 19/11/2020 12:25 pm, Jeff Urban wrote:

Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.

To answer your question: the N-channel MOSFETs are usually operated with
their drain more positive than the source, making the gate more positive
than the source makes them more conductive drain-source, making the gate
negative of the source makes them turn off. A small number are available
as Depletion variety whereby they are already conductive when the gate
is at zero volts (wrt to source) and so you actually need to drive the
gate negative to get them off. The great majority of N-channel mosfets
are Enhancement variety which are already fully off at zero gate volts.
N-channel mosfets are conceptually a little bit like NPN bipolar
transistors (overlooking massive things like gates having no base
current, poorly defined turn-on voltage etc etc etc). N-channel mosfets
are available in the largest range right up to high voltages.

P-channel mosfets are exactly the opposite, the drain is usually
operated negative of the source, driving the gate negative of the source
makes them conductive, at zero or positive gate volts (wrt source) they
are off. They currently exist only as enhancement devices. They are
conceptually a little bit like a PNP bipolar (grossly overlooking all
the huge differences hinted at above). P-channel mosfets tend to need
larger die area to get same on-resistance as a similar N device, are
generally harder to make and so cost more. Really high voltage devices
don\'t exist yet. The variety made is smaller.

All that is explained much better in books like the Art of Electronics
or on zillions of web-pages.

piglet

Nice, being a single ended class A type, I will pick N or P (fet or bipolar)
depending on where I want ground to be. Except in extreme cases the polarity
shouldn\'t matter too much.

George H.

 

[Lasse Langwadt Christensen]

fredag den 20. november 2020 kl. 00.25.36 UTC+1 skrev George Herold:

On Thursday, November 19, 2020 at 4:51:32 PM UTC-5, John Larkin wrote:
On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH
We don\'t know if the OP wants to drive motors or speakers or rail
guns.
Yeah. The load is important. R\'s are easy.
Walking around thinking, I don\'t really like the multi-tapped
G-amp anymore than the two tap A/B amp. (+/-)
When driving weird loads cross-over distortion.. hic-ups is a concern.
I\'m thinking the 3 tap class G thing has three times as many
cross-overs... depending on the amplitude.

afaiu schottkys help and unlike usually cross-overs the switching happens
at higher output so the relative error is smaller

So how about a class D amp doing a (relatively) slow power rail.
(say 1 ms)
and a class A amp inside doing the fast stuff. (1 us?)
I\'m thinking single sided.
That wouldn\'t work for a short pulse.

that\'s basically class-H, a switching supply that maintains a few volts
of headroom on a linear amplifier

 

[John Larkin]

On Thu, 19 Nov 2020 15:25:29 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Thursday, November 19, 2020 at 4:51:32 PM UTC-5, John Larkin wrote:
On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH
We don\'t know if the OP wants to drive motors or speakers or rail
guns.

Yeah. The load is important. R\'s are easy.
Walking around thinking, I don\'t really like the multi-tapped
G-amp anymore than the two tap A/B amp. (+/-)
When driving weird loads cross-over distortion.. hic-ups is a concern.
I\'m thinking the 3 tap class G thing has three times as many
cross-overs... depending on the amplitude.

So how about a class D amp doing a (relatively) slow power rail.
(say 1 ms)
and a class A amp inside doing the fast stuff. (1 us?)
I\'m thinking single sided.
That wouldn\'t work for a short pulse.

George H.

A real class-D amp is better than any human can tell, assuming we are
talking audio here. That\'s certainly a reasonable way to get
kilowatts.

I think there is a class of RF power amps that modulate the power
supplies of the final, to track the RF envelope. Delay lines are
involved I recall.

 

[Bill Sloman]

On Friday, November 20, 2020 at 2:52:25 AM UTC+11, George Herold wrote:

On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

And audio amp manufacturers sell them. Sony had a popular unit some thirty years ago.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

But for different reasons. Secondary breakdown is a problem in bipolar transistors.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1

Experience is a hard school ...

Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.

There\'s nothing crazy about the idea - it\'s a recognised form of audio-amplifier class-G or -H or something. It\'s also complicated and expensive (though not as expensive as delivery that much power from simpler structure.

--
Bill Sloman, Sydney

 

[Jeff Urban]

I see y\'all fucked this up with style

Now, this amp is not just a good amp, the topology is brad new and not up for discussion. the other day I found a fatal error in it and I fixed that. it was ot that it owuld blow up, it is that it owuld not do what I want it to do.

This is for audiophiles. You want to call them audiophools you go right the fuck ahead but when I see someone with a fifty grand turntable I think \"You know, they might just have money\".

There are other components that take this amp into the three grand range, they will spend that.

The design will not be released for some time. It is new. I have already talked to lawyers about this, just because I could. Anyway, there is no discussion on topography, or complimentaries. All the output devices will be the same polarity.

My question was simple. I am going to and a bunch of these and I want the best reliability. Now I remember PNP silicon transistors going before the NPNs. The opposite was true of germanium to some extent, and fact they made few of them probably because of that.

So, this amp only has a single supply. Extremely high current. If I can use P channel I can use a + supply. Well if it is really just as reliable. If N channel is more reliable I have to go wit a negative source which I can do, but to me it is like thinking upside down.

Maybe I\'\'ll just ask Digikey. And the big chokes, I really want to talk to that company with over $300 each, and who knows on the power transformer. But Digikey won\'t know. They just sell the stuff. (not the transformers though)

 

[server]

On Thu, 19 Nov 2020 15:25:29 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Thursday, November 19, 2020 at 4:51:32 PM UTC-5, John Larkin wrote:
On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH
We don\'t know if the OP wants to drive motors or speakers or rail
guns.

Yeah. The load is important. R\'s are easy.
Walking around thinking, I don\'t really like the multi-tapped
G-amp anymore than the two tap A/B amp. (+/-)
When driving weird loads cross-over distortion.. hic-ups is a concern.
I\'m thinking the 3 tap class G thing has three times as many
cross-overs... depending on the amplitude.

So how about a class D amp doing a (relatively) slow power rail.
(say 1 ms)
and a class A amp inside doing the fast stuff. (1 us?)
I\'m thinking single sided.
That wouldn\'t work for a short pulse.

George H.

Here is a new (to me) class of linear amp: it\'s a full analog
h-bridge, but with added fets to ground either output phase when less
than half swing is needed.

Here\'s my class-D amp:

https://www.dropbox.com/s/9bnfkxwhd14sf02/P902B_Hbr_7.jpg?raw=1

It\'s specified for 200 watts out, but it might output 20 amps peak now
and then. I don\'t know if I really need the schottky diodes; it
depends on the reverse recovery behavior of the fet substrate diodes.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Bill Sloman]

On Friday, November 20, 2020 at 1:10:01 PM UTC+11, Jeff Urban wrote:

I see y\'all fucked this up with style

Now, this amp is not just a good amp, the topology is brand new and not up for discussion. the other day I found a fatal error in it and I fixed that. it was not that it would blow up, it is that it would not do what I want it to do.

This is for audiophiles. You want to call them audiophools you go right the fuck ahead but when I see someone with a fifty grand turntable I think \"You know, they might just have money\".

We know about audiophiles. Douglas Self isn\'t one.

We also know about people who think that they have re-invented the wheel. You may have come up with an ingenious new topology, but the over-whelming majority of people who think that they have don\'t know enough to realise that they haven\'t.

> There are other components that take this amp into the three grand range, they will spend that.

Some of them will.

> The design will not be released for some time. It is new. I have already talked to lawyers about this, just because I could. Anyway, there is no discussion on topography, or complimentaries. All the output devices will be the same polarity.

<snip>

> Maybe I\'\'ll just ask Digikey.

Digikey provides links to data sheets. You aren\'t asking anything difficult, but you didn\'t ask in a way that would prompt a helpful response from people who use lots of power MOS-FETs.

I haven\'t used any for years, so I can\'t say anything useful without doing quite a bit of work.

> And the big chokes, I really want to talk to that company with over $300 each, and who knows on the power transformer. But Digikey won\'t know. They just sell the stuff. (not the transformers though).

Getting small volumes of specialised transformers made is still pretty much a cottage industry. There are plenty of people around who do it, but you want somebody close enough to visit in person.

It\'s not strictly necessary, but it tends to pay off.

--
Bill Sloman, Sydney

 

[Phil Allison]

Bill Sloman wrote:

===============

This is for audiophiles. You want to call them audiophools you go right the fuck ahead but when
I see someone with a fifty grand turntable I think \"You know, they might just have money\".

We know about audiophiles. Douglas Self isn\'t one.

** Fact is, Doug he is one - but clearly not an \"audiophool\".

A term I recall \" John Woodgate \" laid claim to.

http://www.woodjohn.uk/



......... Phil

 

[Tauno Voipio]

On 20.11.20 2.42, John Larkin wrote:

On Thu, 19 Nov 2020 15:25:29 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Thursday, November 19, 2020 at 4:51:32 PM UTC-5, John Larkin wrote:
On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH
We don\'t know if the OP wants to drive motors or speakers or rail
guns.

Yeah. The load is important. R\'s are easy.
Walking around thinking, I don\'t really like the multi-tapped
G-amp anymore than the two tap A/B amp. (+/-)
When driving weird loads cross-over distortion.. hic-ups is a concern.
I\'m thinking the 3 tap class G thing has three times as many
cross-overs... depending on the amplitude.

So how about a class D amp doing a (relatively) slow power rail.
(say 1 ms)
and a class A amp inside doing the fast stuff. (1 us?)
I\'m thinking single sided.
That wouldn\'t work for a short pulse.

George H.


A real class-D amp is better than any human can tell, assuming we are
talking audio here. That\'s certainly a reasonable way to get
kilowatts.

I think there is a class of RF power amps that modulate the power
supplies of the final, to track the RF envelope. Delay lines are
involved I recall.

It is called an EER amplifier (Envelope Erasure and Restoration).

--

-TV

 

[boB]

On Thu, 19 Nov 2020 18:09:54 -0800 (PST), Jeff Urban
<jurb6006@gmail.com> wrote:

I see y\'all fucked this up with style

Now, this amp is not just a good amp, the topology is brad new and not up for discussion. the other day I found a fatal error in it and I fixed that. it was ot that it owuld blow up, it is that it owuld not do what I want it to do.

This is for audiophiles. You want to call them audiophools you go right the fuck ahead but when I see someone with a fifty grand turntable I think \"You know, they might just have money\".

There are other components that take this amp into the three grand range, they will spend that.

The design will not be released for some time. It is new. I have already talked to lawyers about this, just because I could. Anyway, there is no discussion on topography, or complimentaries. All the output devices will be the same polarity.

My question was simple. I am going to and a bunch of these and I want the best reliability. Now I remember PNP silicon transistors going before the NPNs. The opposite was true of germanium to some extent, and fact they made few of them probably because of that.

So, this amp only has a single supply. Extremely high current. If I can use P channel I can use a + supply. Well if it is really just as reliable. If N channel is more reliable I have to go wit a negative source which I can do, but to me it is like thinking upside down.

Maybe I\'\'ll just ask Digikey. And the big chokes, I really want to talk to that company with over $300 each, and who knows on the power transformer. But Digikey won\'t know. They just sell the stuff. (not the transformers though)

It matters a lot if it is going to be a switching amp or a linear
amplifier as far as power FETs go so.

Whos says it is a great amplifier ? You or the audiophiles ?

The audiophiles that will spend money won\'t care or be able to tell if
it is better than most any other amplifier of the same power rating
pretty much. If it costs a lot of money and you can feed them
bullshit, they might just buy it.

 

[Phil Allison]

boB wrote:
=======
<

It matters a lot if it is going to be a switching amp or a linear
amplifier as far as power FETs go so.

** Really? IRF hexfets are used in both.

But you need complementary pairs for a Class B amp and that limits the choices considerably.

Types IRFP240 & IRFP9240 have been used often in that mode.


..... Phil

 

[Bill Sloman]

On Friday, November 20, 2020 at 7:50:51 PM UTC+11, palli...@gmail.com wrote:

Bill Sloman wrote:

==============> > > This is for audiophiles. You want to call them audiophools you go right the fuck ahead but when
I see someone with a fifty grand turntable I think \"You know, they might just have money\".

We know about audiophiles. Douglas Self isn\'t one.

** Fact is, Doug he is one - but clearly not an \"audiophool\".

Douglas Self is on the Peter Baxandall side of that particular divide. He probably is a \"golden-eared boy\" but prefers to rely on objective measurements rather than subject impressions.

\"Audiophile\" just means somebody who likes sound, but the term has a lot of associations.

A term I recall \"John Woodgate \" laid claim to.

http://www.woodjohn.uk/

He\'s a lot deeper into that particular culture than I ever was, and does seem to have known most of the major players personally. The closest I ever got to Peter Baxandall was working for a guy who did his apprenticeship at the Royal Radar Establishment at Malvern under Peter\'s supervision.

John did try to pass off a Thomas Love Peacock Welsh song here as authentic ancient Welsh, and I caught him at it. He\'s basically sound, but not above trying it on.

--
Bill Sloman, Sydney

 

[Phil Allison]

Bill Sloman wrote:

===============

We know about audiophiles. Douglas Self isn\'t one.

** Fact is, Doug he is one - but clearly not an \"audiophool\".

Douglas Self is on the Peter Baxandall side of that particular divide.

** Yes - very aware of the \"gullible listener\" phenomenon.
The basis of all audiophoolery.

FYI:

I did my bit as well - coming up with the *only published* test procedure
that demonstrates the fallacy in an instant and is easy for any half
technical person to carry out in their own home.

https://sound-au.com/absw.htm

I shall now dub it \" .. the button is not working ? \" test.

So simple, long as you can appreciate what the *null result* implies.


...... Phil

 

[John S]

On 11/19/2020 6:42 PM, John Larkin wrote:

On Thu, 19 Nov 2020 15:25:29 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Thursday, November 19, 2020 at 4:51:32 PM UTC-5, John Larkin wrote:
On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH
We don\'t know if the OP wants to drive motors or speakers or rail
guns.

Yeah. The load is important. R\'s are easy.
Walking around thinking, I don\'t really like the multi-tapped
G-amp anymore than the two tap A/B amp. (+/-)
When driving weird loads cross-over distortion.. hic-ups is a concern.
I\'m thinking the 3 tap class G thing has three times as many
cross-overs... depending on the amplitude.

So how about a class D amp doing a (relatively) slow power rail.
(say 1 ms)
and a class A amp inside doing the fast stuff. (1 us?)
I\'m thinking single sided.
That wouldn\'t work for a short pulse.

George H.


A real class-D amp is better than any human can tell, assuming we are
talking audio here. That\'s certainly a reasonable way to get
kilowatts.

I think there is a class of RF power amps that modulate the power
supplies of the final, to track the RF envelope. Delay lines are
involved I recall.

Doherty amplifier?

 

[piglet]

On 20/11/2020 2:09 am, Jeff Urban wrote:

I see y\'all fucked this up with style

Now, this amp is not just a good amp, the topology is brad new and not up for discussion. the other day I found a fatal error in it and I fixed that. it was ot that it owuld blow up, it is that it owuld not do what I want it to do.

This is for audiophiles. You want to call them audiophools you go right the fuck ahead but when I see someone with a fifty grand turntable I think \"You know, they might just have money\".

There are other components that take this amp into the three grand range, they will spend that.

The design will not be released for some time. It is new. I have already talked to lawyers about this, just because I could. Anyway, there is no discussion on topography, or complimentaries. All the output devices will be the same polarity.

My question was simple. I am going to and a bunch of these and I want the best reliability. Now I remember PNP silicon transistors going before the NPNs. The opposite was true of germanium to some extent, and fact they made few of them probably because of that.

So, this amp only has a single supply. Extremely high current. If I can use P channel I can use a + supply. Well if it is really just as reliable. If N channel is more reliable I have to go wit a negative source which I can do, but to me it is like thinking upside down.

Maybe I\'\'ll just ask Digikey. And the big chokes, I really want to talk to that company with over $300 each, and who knows on the power transformer. But Digikey won\'t know. They just sell the stuff. (not the transformers though)

Your mention of chokes reminds me of this interesting and unusual amplifier:

<https://www.dropbox.com/s/df5kxw3wsjw73pz/ChokeLoadedAmplifierElectronics-World-1999-11.pdf?dl=0>

Perhaps you can get your rich audiophools to avoid the toxic and nuclear
contaminated mains power line and go for the pure hum-free silence of
battery!

piglet

 

[George Herold]

On Thursday, November 19, 2020 at 10:36:56 PM UTC-5, jla...@highlandsniptechnology.com wrote:

On Thu, 19 Nov 2020 15:25:29 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 4:51:32 PM UTC-5, John Larkin wrote:
On Thu, 19 Nov 2020 09:12:04 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 11:51:58 AM UTC-5, piglet wrote:
On 19/11/2020 15:52, George Herold wrote:
On Thursday, November 19, 2020 at 10:37:06 AM UTC-5, jla...@highlandsniptechnology.com wrote:
On Thu, 19 Nov 2020 05:31:20 -0800 (PST), George Herold
gghe...@gmail.com> wrote:

On Thursday, November 19, 2020 at 7:25:48 AM UTC-5, Jeff Urban wrote:
Many know I set out to build a really good amp. Well after all that I found it can\'t work. The drawing was on the bench and I saw the problem immediately, at a glance. Damn.

But I did find it. Now it needs power MOSFETs for outputs. This looks pretty much non-negotiable.

I forget which is which but they are all the same. Al either ?N channel or P channel. The difference it the power supply. Which is easier to design, but what if the better choice need negative, ? Then I draw it upside down, so what ?

So which is better or more linear or whatever ?

We are in the 140V/18A range.
Is this a linear amp? If so that\'s a lot of heat.
Do you have \"Art of Electronics\". (The 2nd ed. is probably fairly cheap now.)

George H.
The problem is not well specified. \"Good amp\" is not very clear.

Class-D amps are simple and efficient. I\'m designing one right now.

Most mosfets are designed for switching and don\'t take kindly to
linear operation, way out there on their SOAR curve. They tend to blow
up at some fraction of their rated power dissipation; bipolars do that
too.

We learned about that.

https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
Here\'s a crazy idea... ( idea stolen from a linear power supply with stepped taps
on the transformer.) How about a linear amp (inner loop) with some switched
power supply rails... ? It would probably be ugly.
George H.

Yep, it\'s been done already. Goes by weird names like class \"H\" or \"G\"
or whatever marketing thinks sounds cool.

piglet
Thanks piglet, you can tell I\'m an audio expert. :^)
Not much when searching for class G/H but this seems good.
https://sound-au.com/articles/class-g.htm

GH
We don\'t know if the OP wants to drive motors or speakers or rail
guns.

Yeah. The load is important. R\'s are easy.
Walking around thinking, I don\'t really like the multi-tapped
G-amp anymore than the two tap A/B amp. (+/-)
When driving weird loads cross-over distortion.. hic-ups is a concern.
I\'m thinking the 3 tap class G thing has three times as many
cross-overs... depending on the amplitude.

So how about a class D amp doing a (relatively) slow power rail.
(say 1 ms)
and a class A amp inside doing the fast stuff. (1 us?)
I\'m thinking single sided.
That wouldn\'t work for a short pulse.

George H.

Here is a new (to me) class of linear amp: it\'s a full analog
h-bridge, but with added fets to ground either output phase when less
than half swing is needed.
Hmm OK, do you have to make the fets switch on at the zero crossing?

George H.

Here\'s my class-D amp:

https://www.dropbox.com/s/9bnfkxwhd14sf02/P902B_Hbr_7.jpg?raw=1

It\'s specified for 200 watts out, but it might output 20 amps peak now
and then. I don\'t know if I really need the schottky diodes; it
depends on the reverse recovery behavior of the fet substrate diodes.
--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard