OT: Power BJT Power Limit...

[Jasen Betts]

On 2020-07-26, Cursitor Doom <curd@notformail.com> wrote:

Gentlemen,

Taking the 2N3055 as an example (as I\'m sure we\'re all familiar with
this once-ubiquitous decades-old device) say if you were to rig up
some apparatus which enabled you to flood its case with a stream of
say liquid helium, how much power could you wring out of it? I don\'t
mean theoretically, I mean *practically* taking into account its
real-world limitations.

None whatsoever.

Liquid helium would freeze out all the carriers.

.. Bipolar transistors: Ordinary Si bipolars (Si BJTs) suffer a rapid
.. decline in gain with cooling and are unusable below about 100 K

http://www.extremetemperatureelectronics.com/tutorial3.html

--
Jasen.

 

[Jasen Betts]

On 2020-07-26, Cursitor Doom <curd@notformail.com> wrote:

On Sun, 26 Jul 2020 11:06:48 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 26 Jul 2020 17:50:05 +0100, Cursitor Doom
curd@notformail.com> wrote:

Gentlemen,

Taking the 2N3055 as an example (as I\'m sure we\'re all familiar with
this once-ubiquitous decades-old device) say if you were to rig up
some apparatus which enabled you to flood its case with a stream of
say liquid helium, how much power could you wring out of it? I don\'t
mean theoretically, I mean *practically* taking into account its
real-world limitations. Any idea?

Thanks,

CD

Bipolar transistors don\'t work at liquid helium temps! Better try
liquid nitrogen. Or cold water.

Okay, the liquid helium bit is unworkable for various reasons. Let\'s
be realistic and say forced water cooling. Mount the transistor on a
finned copper heatskink and force water through the fins sufficiently
fast to carry away the excess heat. Under those circs., how many Watts
could be screwed out of it? The normal max dissipation for this device
is 115W and there\'s a datasheet here:

https://www.onsemi.com/pub/Collateral/2N3055-D.PDF

With tactics like that you can get 200W from a TO220 package (people
do that and write it in their data sheet), so maybe 300W from the
larger 2N3055 if it was built with the same care, but I don\'t think it
is.

--
Jasen.

 

[server]

On Mon, 27 Jul 2020 06:03:34 -0000 (UTC), Jasen Betts
<jasen@xnet.co.nz> wrote:

On 2020-07-26, Cursitor Doom <curd@notformail.com> wrote:
Gentlemen,

Taking the 2N3055 as an example (as I\'m sure we\'re all familiar with
this once-ubiquitous decades-old device) say if you were to rig up
some apparatus which enabled you to flood its case with a stream of
say liquid helium, how much power could you wring out of it? I don\'t
mean theoretically, I mean *practically* taking into account its
real-world limitations.

None whatsoever.

Liquid helium would freeze out all the carriers.

. Bipolar transistors: Ordinary Si bipolars (Si BJTs) suffer a rapid
. decline in gain with cooling and are unusable below about 100 K

http://www.extremetemperatureelectronics.com/tutorial3.html

Cryo-diodes are neat. A PN diode\'s Vf goes up radically below 20K, and
they get ohmic. Instead of mV/K, you get volts/K at the low end. The
usual current is 10 uA.

Lakeshore makes nicely calibrated cryo-diodes. I did the cryo
instrumentation for Jlabs and the helium plant for SSC.





--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[David Lesher]

bitrex <user@example.net> writes:

LTSpice includes thermal modelling blocks, you could probably use it to
model liquid cooling loops, too.

Not that it makes much sense in most applications to liquid-cool BJTs.
Maybe in avionics bays in aircraft or on spaceships something.

Some guy named Seymour Cray thought it worthwhile.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that\'s close..........................
Unless the host (that isn\'t close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[John Larkin]

On Sun, 26 Jul 2020 16:04:54 -0400, bitrex <user@example.net> wrote:

On 7/26/2020 2:06 PM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jul 2020 17:50:05 +0100, Cursitor Doom
curd@notformail.com> wrote:

Gentlemen,

Taking the 2N3055 as an example (as I\'m sure we\'re all familiar with
this once-ubiquitous decades-old device) say if you were to rig up
some apparatus which enabled you to flood its case with a stream of
say liquid helium, how much power could you wring out of it? I don\'t
mean theoretically, I mean *practically* taking into account its
real-world limitations. Any idea?

Thanks,

CD

Bipolar transistors don\'t work at liquid helium temps! Better try
liquid nitrogen. Or cold water.







LTSpice includes thermal modelling blocks, you could probably use it to
model liquid cooling loops, too.

Not that it makes much sense in most applications to liquid-cool BJTs.
Maybe in avionics bays in aircraft or on spaceships something.

The heat sinks in LT Spice are sort of cartoons. They are OK if you
assume lumped models. Real life gets a lot more complex. As usual, the
HELP isn\'t much help.

I\'m liquid cooling some SiC fets in my Pockels Cell driver. To make
things fast, it helps to use a small part and push it hard.

 

[whit3rd]

On Monday, July 27, 2020 at 12:29:10 PM UTC-7, David Lesher wrote:

bitrex <user@example.net> writes:

Not that it makes much sense in most applications to liquid-cool BJTs.
Maybe in avionics bays in aircraft or on spaceships something.

Some guy named Seymour Cray thought it worthwhile.

The usual run of non-desktop computing included refrigeration (or at least
chilled water) in the computer room. It still does, even if air-cooling
operates on the last-meter length scale.

 

[Martin Brown]

On 26/07/2020 17:51, Phil Hobbs wrote:

On 2020-07-26 12:50, Cursitor Doom wrote:
Gentlemen,

Taking the 2N3055 as an example (as I\'m sure we\'re all familiar with
this once-ubiquitous decades-old device) say if you were to rig up
some apparatus which enabled you to flood its case with a stream of
say liquid helium, how much power could you wring out of it? I don\'t
mean theoretically, I mean *practically* taking into account its
real-world limitations. Any idea?

It would probably be limited by die cracking due to differential thermal
expansion at the high voltage end and bond wires blowing off at the high
current end.

I recall an infamous PWM X10 power amplifier designed in 1964 by
idiosyncratic but brilliant Ivor Catt for Clive Sinclair that was class
D using seriously under rated germanium transistors in hard saturation.
The thin bond out wires eventually failed due to vibration from the high
currents interacting with the Earth\'s magnetic field. The power rating
of the transistors was not actually exceeded but their tolerance of
brutal currents flowing in them was. It wasn\'t a commercial success but
it put him on the map. I thought I had imagined it until I found this OU
document where the X10 gains honourable mention on p13 although being a
marketing course it doesn\'t mention the technical cause of failure.

It actually worked pretty well for the price but died soon enough if
used at anything more than 25% of rated power output that they had a lot
of very unhappy customers. The later X20 did OK and they went on to
develop quite a hobby following with various kits and very early cheap
calculators and digital watches the size of a matchbox!

http://www.sinclairql.net/downloads/1986_Sinclair_QL_microcomputer_case_study_by_Godfrey_Boyle_OpenUniversity_T362_Block_2_Marketing-SCN04-SQPP.pdf

Top left of page 13 describes the thing. Later on Catt was better known
for advocating wafer scale integration and railing against relativity.

The QL was doomed by Sir Clive\'s insistence that it used his own tape
microdrives (so prone to jamming) rather than floppy disks. The rather
tacky keyboard didn\'t help but was much better than a ZX80 one! Apart
from that it was a good machine with a 68008 CPU and a Basic dialect
that was well ahead of its time. Sadly it never became very popular.

Amstrad kit launched at about the same time took the most market share
in the small business arena and the rest is history.

--
Regards,
Martin Brown

 

[Phil Allison]

Martin Brown wrote:
--------------------

I recall an infamous PWM X10 power amplifier designed in 1964 by
idiosyncratic but brilliant Ivor Catt

** Really ? That IS interesting.

Bet he keeps real quiet about it.

The thin bond out wires eventually failed due to vibration from the high
currents interacting with the Earth\'s magnetic field.

** Not credible.

Later on Catt was better known
for advocating wafer scale integration and railing against relativity.

** Has was also know for Wireless World articles about capacitors and transmission lines being the same.

Until \" Ouida Dogg\" came along and took a few bites out of him.

( Get it \" I\'ve a cat / \" we\'d a dog \" ? )

Hysterical stuff, for conservative WW mag.



....... Phil

 

[server]

>Use liquid hydrogen!

Yeah, a Hindenburg device. Send some to China in exchange for their virus.

 

[server]

>We use one fet that\'s claimed to be able to dissipate 1000 watts

The highest dissipation I have ever seen for a transistor was 625 watts. Made by Westinghouse and slow as hell. I am sure it it no longer available. To even find the part number would take me days in my ancient spec book.

If you can directly cool the die you can get quite a bit. The limiting factor other than current ad voltage is the thermal resistance to the case. So maybe you could take a 2N3055 and drill two holes in it and pump coolant right inside of it.

Of course there are no guarantees.

 

[Clive Arthur]

On 28/07/2020 12:17, Phil Allison wrote:

Martin Brown wrote:
--------------------


I recall an infamous PWM X10 power amplifier designed in 1964 by
idiosyncratic but brilliant Ivor Catt


** Really ? That IS interesting.

Bet he keeps real quiet about it.


The thin bond out wires eventually failed due to vibration from the high
currents interacting with the Earth\'s magnetic field.

** Not credible.


Later on Catt was better known
for advocating wafer scale integration and railing against relativity.


** Has was also know for Wireless World articles about capacitors and transmission lines being the same.

Until \" Ouida Dogg\" came along and took a few bites out of him.

( Get it \" I\'ve a cat / \" we\'d a dog \" ? )

Hysterical stuff, for conservative WW mag.



...... Phil

And don\'t for get \'Weaver Mowse\' who had at least one letter published.

--
Cheers
Clive

 

[server]

On Tue, 28 Jul 2020 04:59:37 -0700 (PDT), jurb6006@gmail.com wrote:

We use one fet that\'s claimed to be able to dissipate 1000 watts

The highest dissipation I have ever seen for a transistor was 625 watts. Made by Westinghouse and slow as hell. I am sure it it no longer available. To even find the part number would take me days in my ancient spec book.

If you can directly cool the die you can get quite a bit. The limiting factor other than current ad voltage is the thermal resistance to the case. So maybe you could take a 2N3055 and drill two holes in it and pump coolant right inside of it.

Of course there are no guarantees.

The big one is IXFH400N075T2. We tested a lot of mosfets for survival
as linear amps, in a 17 KW NMR gradient amp, used for micro-imaging.
It was the best n-channel we could find.

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

https://www.dropbox.com/s/lrrhgp564oefyi8/Amp.jpg?raw=1


That design taught us to be skeptical of SOAR curves on data sheets.





--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Tony Stewart]

On Tue. 28 Jul.-20 7:59 a.m., jurb6006@gmail.com wrote:

We use one fet that\'s claimed to be able to dissipate 1000 watts

The highest dissipation I have ever seen for a transistor was 625 watts. Made by Westinghouse and slow as hell. I am sure it it no longer available. To even find the part number would take me days in my ancient spec book.

If you can directly cool the die you can get quite a bit. The limiting factor other than current ad voltage is the thermal resistance to the case. So maybe you could take a 2N3055 and drill two holes in it and pump coolant right inside of it.

Of course there are no guarantees.

I have used snow,ice, a toaster, a power diode and 120Vac to start my
car in the dead of winter at -30\'C in the 80\'s

I would connect Neutral to Vbat Gnd and Line thru the toaster to the
diode in a jar of water with ice in it to start the car in few minutes
when the battery was in poor condition. The peak current was enough to
charge the battery.

 

[Jeroen Belleman]

Clive Arthur wrote:

On 28/07/2020 12:17, Phil Allison wrote:
Martin Brown wrote:
--------------------


I recall an infamous PWM X10 power amplifier designed in 1964 by
idiosyncratic but brilliant Ivor Catt


** Really ? That IS interesting.

Bet he keeps real quiet about it.


The thin bond out wires eventually failed due to vibration from the high
currents interacting with the Earth\'s magnetic field.

** Not credible.


Later on Catt was better known
for advocating wafer scale integration and railing against relativity.


** Has was also know for Wireless World articles about capacitors and
transmission lines being the same.

Until \" Ouida Dogg\" came along and took a few bites out of him.

( Get it \" I\'ve a cat / \" we\'d a dog \" ? )

Hysterical stuff, for conservative WW mag.



...... Phil

And don\'t for get \'Weaver Mowse\' who had at least one letter published.

It might have been fun to have Catt here, on s.e.d.

Jeroen Belleman

 

[server]

On Tue, 28 Jul 2020 11:04:19 -0400, Tony Stewart
<tony.sunnysky@gmail.com> wrote:

On Tue. 28 Jul.-20 7:59 a.m., jurb6006@gmail.com wrote:
We use one fet that\'s claimed to be able to dissipate 1000 watts

The highest dissipation I have ever seen for a transistor was 625 watts. Made by Westinghouse and slow as hell. I am sure it it no longer available. To even find the part number would take me days in my ancient spec book.

If you can directly cool the die you can get quite a bit. The limiting factor other than current ad voltage is the thermal resistance to the case. So maybe you could take a 2N3055 and drill two holes in it and pump coolant right inside of it.

Of course there are no guarantees.


I have used snow,ice, a toaster, a power diode and 120Vac to start my
car in the dead of winter at -30\'C in the 80\'s

I would connect Neutral to Vbat Gnd and Line thru the toaster to the
diode in a jar of water with ice in it to start the car in few minutes
when the battery was in poor condition. The peak current was enough to
charge the battery.

A diode and an incandescent bulb would work too.

I have charged a dead car battery with an ancient 18-volt modem
wall-wart. It got too hot, so I added a heat gun in series as a
ballast resistor.

Now I keep a bench power supply at home, and a few diodes and
resistors. And a DVM of course. That\'s useful for all sorts of stuff,
now and then.

There is a theory promoted by car-parts stores that a dead battery is
permanently ruined. They sell chargers that won\'t put any current into
a zero-volts battery, just to make their point.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[whit3rd]

On Tuesday, July 28, 2020 at 4:17:51 AM UTC-7, Phil Allison wrote:

Martin Brown wrote:
--------------------


I recall an infamous PWM X10 power amplifier designed in 1964 by
idiosyncratic but brilliant Ivor Catt

The thin bond out wires eventually failed due to vibration from the high
currents interacting with the Earth\'s magnetic field.

** Not credible.

Well, maybe it is. The technology of the day was weak on switchmode
circuitry, and I\'ve seen exploded-wire failures (in metal cases, just file
off the lid and aim a microscope at the problem).

The dI/dt limit on a few millimeters of wire was due to magnetic
forces, skin effect, and shockwve (ultrasonic) stresses. Not the
terrestrial field, the current-induced field. Unlike thermal failure,
there\'s no blob of melt at the end of the exploded wire... it\'s just
GONE.

 

[Phil Hobbs]

On 2020-07-28 12:10, jlarkin@highlandsniptechnology.com wrote:

On Tue, 28 Jul 2020 11:04:19 -0400, Tony Stewart
tony.sunnysky@gmail.com> wrote:

On Tue. 28 Jul.-20 7:59 a.m., jurb6006@gmail.com wrote:
We use one fet that\'s claimed to be able to dissipate 1000 watts

The highest dissipation I have ever seen for a transistor was 625 watts. Made by Westinghouse and slow as hell. I am sure it it no longer available. To even find the part number would take me days in my ancient spec book.

If you can directly cool the die you can get quite a bit. The limiting factor other than current ad voltage is the thermal resistance to the case. So maybe you could take a 2N3055 and drill two holes in it and pump coolant right inside of it.

Of course there are no guarantees.


I have used snow,ice, a toaster, a power diode and 120Vac to start my
car in the dead of winter at -30\'C in the 80\'s

I would connect Neutral to Vbat Gnd and Line thru the toaster to the
diode in a jar of water with ice in it to start the car in few minutes
when the battery was in poor condition. The peak current was enough to
charge the battery.

A diode and an incandescent bulb would work too.

I have charged a dead car battery with an ancient 18-volt modem
wall-wart. It got too hot, so I added a heat gun in series as a
ballast resistor.

Now I keep a bench power supply at home, and a few diodes and
resistors. And a DVM of course. That\'s useful for all sorts of stuff,
now and then.

There is a theory promoted by car-parts stores that a dead battery is
permanently ruined. They sell chargers that won\'t put any current into
a zero-volts battery, just to make their point.

I have an 3A/10A Craftsman charger from the late \'80s--just a
transformer, slide switch for tap selection, and a bridge rectifier.
WDNNS smart chargers for cars.

(Well, I also have a battery minder for my electric-start generator,
which is comforting.)

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 Hobbs]

On 2020-07-28 07:50, jurb6006@gmail.com wrote:

Use liquid hydrogen!

Yeah, a Hindenburg device. Send some to China in exchange for their virus.

Heike Kamerlingh Onnes used a three-stage glass dewar for his helium
liquification experiments. The first stage had LN2, the third stage had
LHe, but the second stage had (iirc) about three litres of LH2, all in a
glass flask.

Brr.

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

 

[Rich S]

On Tuesday, July 28, 2020 at 3:04:24 PM UTC, Anthony Stewart wrote:

On Tue. 28 Jul.-20 7:59 a.m., jurb6006@gmail.com wrote:
We use one fet that\'s claimed to be able to dissipate 1000 watts

The highest dissipation I have ever seen for a transistor was 625 watts. Made by Westinghouse and slow as hell. I am sure it it no longer available. To even find the part number would take me days in my ancient spec book.

If you can directly cool the die you can get quite a bit. The limiting factor other than current ad voltage is the thermal resistance to the case. So maybe you could take a 2N3055 and drill two holes in it and pump coolant right inside of it.

Of course there are no guarantees.


I have used snow,ice, a toaster, a power diode and 120Vac to start my
car in the dead of winter at -30\'C in the 80\'s

I would connect Neutral to Vbat Gnd and Line thru the toaster to the
diode in a jar of water with ice in it to start the car in few minutes
when the battery was in poor condition. The peak current was enough to
charge the battery.

Did you prepare breakfast (toast) at the same time?

 

[server]

On Tuesday, 28 July 2020 17:49:52 UTC+1, whit3rd wrote:

On Tuesday, July 28, 2020 at 4:17:51 AM UTC-7, Phil Allison wrote:
Martin Brown wrote:
--------------------


I recall an infamous PWM X10 power amplifier designed in 1964 by
idiosyncratic but brilliant Ivor Catt

The thin bond out wires eventually failed due to vibration from the high
currents interacting with the Earth\'s magnetic field.

** Not credible.

Well, maybe it is. The technology of the day was weak on switchmode
circuitry, and I\'ve seen exploded-wire failures (in metal cases, just file
off the lid and aim a microscope at the problem).

The dI/dt limit on a few millimeters of wire was due to magnetic
forces, skin effect, and shockwve (ultrasonic) stresses. Not the
terrestrial field, the current-induced field. Unlike thermal failure,
there\'s no blob of melt at the end of the exploded wire... it\'s just
GONE.

I recently tested some pcb mounted fuses to see how well they would
survive the startup surge of a dc input power supply where a large
capacitor was charged up very fast.
After around 100,000 startups the fuse would fail from metal fatigue
at the points where the fuse wire is welded to the connection wires.
The peak current was around 30 to 50 times the rated current of the fuse
for a few tens of microseconds.
I also repeated the test with a powerful magnet on top of the fuse
to see whether this made any difference. It did not.

I think the fuse wire \"instantaneously\" lengthened, thereby changing
the angle of the wire at the terminations, effectively bending it
backwards and forwards slightly each time. The geometry is probably
very similar to that of bond wires in a power transistor.

John