AoE x-Chapters, using power MOSFETs as linear transistors

On 7/26/19 11:29 AM, Winfield Hill wrote:
bitrex wrote...

The idea i'm messing with is bring the frequency down to something
more sensible from the self-resonant of a couple hundred MHz with
some low-loss inductance in series. Then use some negative resistance
to compensate for the bad Q down there. Can all be done with FETs
and BJTs, at low voltages.

You might want to experiment with piglet (Eric Wagner)'s idea
of adapting a foldback current-limit circuit into a negative-
resistance current source. We wrote it up for section 2x.12,
in the AoE x-Chapters book, see draft copy on DropBox.

https://www.dropbox.com/s/2urywtwwlpt6sjb/2x.12_negative-resistance_WH.pdf?dl=1

I played with SPICE and added a 100uA 1.5-volt low-voltage
version. It might be fast enough, if you scale the resistors
to run it at 2mA or even 10mA. You might do a pnp version.
Click to expand...

Apologies for the message/.asc spam earlier, but here is a working revision:

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TEXT -464 48 Left 2 !.tran 10m
TEXT 1592 1488 Left 5 ;Lossy L
TEXT -744 296 Left 5 ;Kickstarter (sim only)
 
piglet wrote...
On 26/07/2019 7:23 pm, George Herold wrote:
Instead of "With a little prodding" you might substitute,
"For a few haycorns". :^)

GH

:) I get a mention in the great book - Yay!

piglet
Click to expand...

We used your real name, rather than piglet,
would you prefer that moniker was included?


--
Thanks,
- Win
 
In article <0prmje1b7bqoes83jlehpif5tlgjsco7t7@4ax.com>,
John Larkin <jjlarkin@highland_snip_technology.com> wrote:

https://www.profusionplc.com/parts/ecw20n20

"They offer superb sonic characteristics"

What can that mean?
Click to expand...

Whatever the Marketing people want it to. :)

>Does Hitachi still make laterals? I couldn't find them.

As far as I can tell, Hitachi/Renesas is no longer making laterals.
These seem to have gone entirely out of the market supply-chain years
ago.

I read one person's comment that suggested that laterals were a victim
of one of the big Japanese earthquakes, some years ago (possibly the
Miyagi quake of 2008 although I'm not certain). Several of the
Japanese earthquakes in the last decade-and-change had a serious
impact on semiconductor-manufacturing facilities, with production of
many items being shut down.

Lateral MOSFETs may have been one type which wasn't in-demand enough
to merit restarting (or rebuilding) the production lines after the
rubble stopped bouncing around.
 
lørdag den 27. juli 2019 kl. 00.53.33 UTC+2 skrev Dave Platt:
In article <0prmje1b7bqoes83jlehpif5tlgjsco7t7@4ax.com>,
John Larkin <jjlarkin@highland_snip_technology.com> wrote:

https://www.profusionplc.com/parts/ecw20n20

"They offer superb sonic characteristics"

What can that mean?

Whatever the Marketing people want it to. :)

Does Hitachi still make laterals? I couldn't find them.

As far as I can tell, Hitachi/Renesas is no longer making laterals.
These seem to have gone entirely out of the market supply-chain years
ago.

I read one person's comment that suggested that laterals were a victim
of one of the big Japanese earthquakes, some years ago (possibly the
Miyagi quake of 2008 although I'm not certain). Several of the
Japanese earthquakes in the last decade-and-change had a serious
impact on semiconductor-manufacturing facilities, with production of
many items being shut down.

Lateral MOSFETs may have been one type which wasn't in-demand enough
to merit restarting (or rebuilding) the production lines after the
rubble stopped bouncing around.
Click to expand...

isn't many of the RF power fets lateral? like the MRF101BN , MRF300AN mentioned a few days ago
 
On Wednesday, July 24, 2019 at 10:59:46 AM UTC-4, Winfield Hill wrote:
DRAFT copy of a useful section in the upcoming
AoE x-Chapters, about using power MOSFETs as
linear transistors. Subthreshold region, etc.
Comments, errors found, etc. Thanks!

https://www.dropbox.com/s/0ph15moamo0mlt4/3x.5_MOSFETs_Linear-Transistors_DRAFT.pdf?dl=1
Click to expand...

I'm using some big mosfet as part of a 77k to 400K heater.
The Fet's 'down the probe' with three to-220 pack R's.
(The R's and supply voltage limit the power to a few watts.)
An opamp up top closes the loop... I've added various C's
to the loop to slow things down...
At some point my design becomes, bang on various 'ports'
and try to damp out the ringing.

(If no ringing, then maybe something can be faster?)

George H.
--
Thanks,
- Win
Click to expand...
 
On Friday, July 26, 2019 at 5:10:33 PM UTC-4, piglet wrote:
On 26/07/2019 7:23 pm, George Herold wrote:
Instead of "With a little prodding" you might substitute,
"For a few haycorns". :^)

GH

:) I get a mention in the great book - Yay!

piglet
Click to expand...

Sweet!
I don't really understand how it works.. :^)

Hey, mentioning 'great books' did you see this,
(some computer conjecture proven)
https://www.scottaaronson.com/blog/?p=4229
Mind you, I'm mostly clueless...
so I don't understand parts,
which is part of being a pooh bear. :^)

Hey would you send me an email to;
gherold.. at sign.... teachspin,com
that comma should be a period.

George H.
 
George Herold wrote...
An opamp up top closes the loop... I've added
various C's to the loop to slow things down...
Click to expand...

Depending on where you add the C's, they may
simply add poles, or lower pole frequencies,
to destabilize the feedback loop.


--
Thanks,
- Win
 
On Friday, July 26, 2019 at 9:49:39 PM UTC-4, Winfield Hill wrote:
George Herold wrote...

An opamp up top closes the loop... I've added
various C's to the loop to slow things down...

Depending on where you add the C's, they may
simply add poles, or lower pole frequencies,
to destabilize the feedback loop.
Right, 1/2 the time I need more R in the loop.
Click to expand...

George H.
--
Thanks,
- Win
Click to expand...
 
On Fri, 26 Jul 2019 20:00:57 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

John Larkin wrote:



** However, Larkin failed to do the *bleeding obvious thing* and use MOSFETs characterised for liner operation - ie Lateral types as made by Hitachi and others.

Another example of his massive and insane prejudice against any and all things that even smack of "audio".

Wot a cretin.



This cretin designs and sells a lot of electronics,


** So fucking what?

You are a king size cretin anyway.



Can you suggest some part numbers for high power n and p channel
lateral fets? Something in the 200 volt, 400 watt ballpark?


**Plenty of 250V laterals available, some even higher, in both P and N.
Click to expand...

Got links?


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Fri, 26 Jul 2019 08:19:52 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 7/25/19 7:55 PM, Phil Allison wrote:
John Larkin wrote:



Back when we were in the NMR gradient driver business, we ran
switcher-type mosfets as constant-current linear amps, with PPM levels
of settling and noise; one box had 20 KW peak output. We just wrapped
an opamp around each fet to hide all the sub-threshold complexities.

What we couldn't hide was blowing up the fets in the far corners of
the SOAR graph.


** However, Larkin failed to do the *bleeding obvious thing* and use MOSFETs characterised for liner operation - ie Lateral types as made by Hitachi and others.

Another example of his massive and insane prejudice against any and all things that even smack of "audio".

Wot a cretin.

Imagine anybody wanting to go faster than 20 kHz. The very _idea_!

Cheers

Phil Hobbs
Click to expand...

What's strange is that many mosfets will switch a lot faster -
sometimes 20x faster - than the numbers on the data sheet.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
Dave Platt wrote:

Does Hitachi still make laterals? I couldn't find them.

As far as I can tell, Hitachi/Renesas is no longer making laterals.
These seem to have gone entirely out of the market supply-chain years
ago.
Click to expand...

** I have about 100 N and P channel Hitachi TO3 mosfets.

Types 2SJ56 and 2SK176, 250V, 8A 125W.

Amplifiers that use them no longer come to me for service so they are up for sale.


..... Phil
 
John Larkin wrote:

** However, Larkin failed to do the *bleeding obvious thing* and use MOSFETs characterised for liner operation - ie Lateral types as made by Hitachi and others.

Another example of his massive and insane prejudice against any and all things that even smack of "audio".

Wot a cretin.



This cretin designs and sells a lot of electronics,
Click to expand...

** So fucking what?

You are a king size cretin anyway.



Can you suggest some part numbers for high power n and p channel
lateral fets? Something in the 200 volt, 400 watt ballpark?
Click to expand...

**Plenty of 250V laterals available, some even higher, in both P and N.

One uses as many as needed with huge advantage over switching types.

Cos you are stubborn, autistic shithead - you have never tried them.


I'm not fundamentally prejudiced against audio,
Click to expand...

** Ridiculous lie.


but most audio design
is really bad and mostly subjective. And boring.
Click to expand...

** Absolute bollocks.


We're using a very nice TI class D "audio" amp in a couple of designs
now.
Click to expand...

** Yawnnnnnnn....



.... Phil
--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Click to expand...
 
Phil Hobbs wrote:

Imagine anybody wanting to go faster than 20 kHz. The very _idea_!
Click to expand...

** Stick to posting about stuff you understand.

Cos you are making a total ass of yourself posting smartarse crap like this.

You are a pathetic wanker - Hobbs.


...... Phil
 
On 26/07/2019 10:54 pm, Winfield Hill wrote:
piglet wrote...

On 26/07/2019 7:23 pm, George Herold wrote:
Instead of "With a little prodding" you might substitute,
"For a few haycorns". :^)

GH

:) I get a mention in the great book - Yay!

piglet

We used your real name, rather than piglet,
would you prefer that moniker was included?
Click to expand...

Thanks Win, real name is fine.

piglet / Erich Wagner
 
On 27/07/2019 2:54 am, George Herold wrote:
Hey, mentioning 'great books' did you see this,
(some computer conjecture proven)
https://www.scottaaronson.com/blog/?p=4229
Mind you, I'm mostly clueless...
so I don't understand parts,
which is part of being a pooh bear. :^)
Click to expand...

Looks too mathesy for me, I will have to reread very slowly several
times. Pooh has brain and wisdom, piglet is just always anxious.

piglet
 
On 7/26/19 11:16 PM, John Larkin wrote:
On Fri, 26 Jul 2019 08:19:52 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 7/25/19 7:55 PM, Phil Allison wrote:
John Larkin wrote:



Back when we were in the NMR gradient driver business, we ran
switcher-type mosfets as constant-current linear amps, with PPM levels
of settling and noise; one box had 20 KW peak output. We just wrapped
an opamp around each fet to hide all the sub-threshold complexities.

What we couldn't hide was blowing up the fets in the far corners of
the SOAR graph.


** However, Larkin failed to do the *bleeding obvious thing* and use MOSFETs characterised for liner operation - ie Lateral types as made by Hitachi and others.

Another example of his massive and insane prejudice against any and all things that even smack of "audio".

Wot a cretin.

Imagine anybody wanting to go faster than 20 kHz. The very _idea_!


What's strange is that many mosfets will switch a lot faster -
sometimes 20x faster - than the numbers on the data sheet.
Click to expand...

That's been so since 1982ish that I know about, and probably as long as
they've existed. Probably to help the apps engineers escape the wrath
of customers who couldn't reproduce the datasheet numbers. ;)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
Phil Allison wrote...
** I have about 100 N and P channel Hitachi TO3 mosfets.
Types 2SJ56 and 2SK176, 250V, 8A 125W.

Amplifiers that use them no longer come to me for
service so they are up for sale.
Click to expand...

eBay.


--
Thanks,
- Win
 
On 7/27/19 12:56 AM, piglet wrote:
On 27/07/2019 2:54 am, George Herold wrote:
Hey, mentioning 'great books' did you see this,
(some computer conjecture proven)
https://www.scottaaronson.com/blog/?p=4229
Mind you, I'm mostly clueless...
so I don't understand parts,
which is part of being a pooh bear. :^)


Looks too mathesy for me, I will have to reread very slowly several
times. Pooh has brain and wisdom, piglet is just always anxious.

piglet
Click to expand...

"That's the bravest kind of not blinching there is." --Pooh

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 7/26/19 10:54 PM, Phil Allison wrote:
Phil Hobbs wrote:


Imagine anybody wanting to go faster than 20 kHz. The very _idea_!



** Stick to posting about stuff you understand.

Cos you are making a total ass of yourself posting smartarse crap like this.

You are a pathetic wanker - Hobbs.


..... Phil
Click to expand...

I'm so relieved to have you protecting my reputation so zealously. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
Winfield Hill wrote:
Phil Allison wrote...

** I have about 100 N and P channel Hitachi TO3 mosfets.
Types 2SJ56 and 2SK176, 250V, 8A 125W.

Amplifiers that use them no longer come to me for
service so they are up for sale.

eBay.
Click to expand...

** Try taking a look.



.... Phil
 
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