\"Shunt\" Resistors...

[Ricketty C]

I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[John S]

On 10/6/2020 12:37 PM, Ricketty C wrote:

I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?

A series resistor is not a \"shunt\". It is a current sensing resistor. A
shunt resistor is in parallel with the meter. If you parallel one
resistor with another, it can be considered a shunt resistor. If you put
a resistor in series with another resistor to read the current, it is
not considered a shunt resistor.

Feel free to call them whatever you like.

 

[John Larkin]

On Tue, 6 Oct 2020 12:56:38 -0500, John S <Sophi.2@invalid.org> wrote:

On 10/6/2020 12:37 PM, Ricketty C wrote:
I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?


A series resistor is not a \"shunt\". It is a current sensing resistor. A
shunt resistor is in parallel with the meter. If you parallel one
resistor with another, it can be considered a shunt resistor. If you put
a resistor in series with another resistor to read the current, it is
not considered a shunt resistor.

Feel free to call them whatever you like.

Right. It doesn\'t care what you call it.

We used to make our own current shunts from sheet manganin. We had
them punched, and we annealed them to relieve stresses. They drove
diffamps in NMR gradient amps, not meters. We epoxied them to
temperature-controlled metal blocks, which had interesting
eddy-current effects.

https://www.dropbox.com/s/nlwbub0yx96krgl/Manganin_Bits.JPG?dl=0

Digikey will sell you surface-mount \"current shunts\", which just means
a very low value resistor intended for current measurement. They are
typically solid metal, not cermet, and sometimes have 4 leads.

Jumpers are sometimes called shunts too.

 

[boB]

On Tue, 06 Oct 2020 12:04:57 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

On Tue, 6 Oct 2020 12:56:38 -0500, John S <Sophi.2@invalid.org> wrote:

On 10/6/2020 12:37 PM, Ricketty C wrote:
I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?


A series resistor is not a \"shunt\". It is a current sensing resistor. A
shunt resistor is in parallel with the meter. If you parallel one
resistor with another, it can be considered a shunt resistor. If you put
a resistor in series with another resistor to read the current, it is
not considered a shunt resistor.

Feel free to call them whatever you like.


Right. It doesn\'t care what you call it.

We used to make our own current shunts from sheet manganin. We had
them punched, and we annealed them to relieve stresses. They drove
diffamps in NMR gradient amps, not meters. We epoxied them to
temperature-controlled metal blocks, which had interesting
eddy-current effects.

https://www.dropbox.com/s/nlwbub0yx96krgl/Manganin_Bits.JPG?dl=0

Digikey will sell you surface-mount \"current shunts\", which just means
a very low value resistor intended for current measurement. They are
typically solid metal, not cermet, and sometimes have 4 leads.

Jumpers are sometimes called shunts too.

We made our own shunts too, for a while out of Cupron wire. Tough
stuff to bend into a loop that is repeatable and stuffable. So we had
a spring company do that. Works great.

The industry calls them shunts AFAIK too even through they are series
resistance. Canadian Shunts is one company we used for 500 amp at 50
mV

Yes, we use the jumper shunts as well. Those may be seires or
parallel in circuit operation...

So, when you have a battery and a light bulb connected together, just
two components, is that a parallel or a series circuit ??

boB

 

[Phil Hobbs]

On 2020-10-07 03:05, boB wrote:

On Tue, 06 Oct 2020 12:04:57 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Tue, 6 Oct 2020 12:56:38 -0500, John S <Sophi.2@invalid.org> wrote:

On 10/6/2020 12:37 PM, Ricketty C wrote:
I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?


A series resistor is not a \"shunt\". It is a current sensing resistor. A
shunt resistor is in parallel with the meter. If you parallel one
resistor with another, it can be considered a shunt resistor. If you put
a resistor in series with another resistor to read the current, it is
not considered a shunt resistor.

Feel free to call them whatever you like.


Right. It doesn\'t care what you call it.

We used to make our own current shunts from sheet manganin. We had
them punched, and we annealed them to relieve stresses. They drove
diffamps in NMR gradient amps, not meters. We epoxied them to
temperature-controlled metal blocks, which had interesting
eddy-current effects.

https://www.dropbox.com/s/nlwbub0yx96krgl/Manganin_Bits.JPG?dl=0

Digikey will sell you surface-mount \"current shunts\", which just means
a very low value resistor intended for current measurement. They are
typically solid metal, not cermet, and sometimes have 4 leads.

Jumpers are sometimes called shunts too.




We made our own shunts too, for a while out of Cupron wire. Tough
stuff to bend into a loop that is repeatable and stuffable. So we had
a spring company do that. Works great.

The industry calls them shunts AFAIK too even through they are series
resistance. Canadian Shunts is one company we used for 500 amp at 50
mV

Yes, we use the jumper shunts as well. Those may be seires or
parallel in circuit operation...

So, when you have a battery and a light bulb connected together, just
two components, is that a parallel or a series circuit ??

boB

BITD a \'meter shunt\' was a resistor whose tempco matched that of the
copper winding of your analogue meter movement, and whose resistance was
some convenient submultiple of the meter\'s resistance, like 1/99 to turn
a 1-mA meter into a 100-mA meter.

Nice not to have to worry about that anymore.

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

 

[Bob Engelhardt]

On 10/6/2020 1:56 PM, John S wrote:
> ... A shunt resistor is in parallel with the meter. ...

Yeah but it\'s in series with the load, a current-sensing resistor. just
sayin\'.

 

[legg]

On Tue, 6 Oct 2020 10:37:19 -0700 (PDT), Ricketty C
<gnuarm.deletethisbit@gmail.com> wrote:

I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?

Both terms are simple and quick expanations of a
component\'s function.

This practice is sometimes mis-used, but I think
you\'ve picked the wrong examples to shake your
stick at.

RL

 

[Phil Hobbs]

On 2020-10-07 08:37, Bob Engelhardt wrote:

On 10/6/2020 1:56 PM, John S wrote:
... A shunt resistor is in parallel with the meter. ...

Yeah but it\'s in series with the load, a current-sensing resistor.  just
sayin\'.

Of course, but if you ordered a current sensing resistor with a tempco
of +3000 ppm/K you\'d be disappointed, whereas that\'s about right for a
meter shunt. So the distinction is entirely worthwhile.

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

 

[server]

On Wed, 7 Oct 2020 05:11:35 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-10-07 03:05, boB wrote:
On Tue, 06 Oct 2020 12:04:57 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Tue, 6 Oct 2020 12:56:38 -0500, John S <Sophi.2@invalid.org> wrote:

On 10/6/2020 12:37 PM, Ricketty C wrote:
I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?


A series resistor is not a \"shunt\". It is a current sensing resistor. A
shunt resistor is in parallel with the meter. If you parallel one
resistor with another, it can be considered a shunt resistor. If you put
a resistor in series with another resistor to read the current, it is
not considered a shunt resistor.

Feel free to call them whatever you like.


Right. It doesn\'t care what you call it.

We used to make our own current shunts from sheet manganin. We had
them punched, and we annealed them to relieve stresses. They drove
diffamps in NMR gradient amps, not meters. We epoxied them to
temperature-controlled metal blocks, which had interesting
eddy-current effects.

https://www.dropbox.com/s/nlwbub0yx96krgl/Manganin_Bits.JPG?dl=0

Digikey will sell you surface-mount \"current shunts\", which just means
a very low value resistor intended for current measurement. They are
typically solid metal, not cermet, and sometimes have 4 leads.

Jumpers are sometimes called shunts too.




We made our own shunts too, for a while out of Cupron wire. Tough
stuff to bend into a loop that is repeatable and stuffable. So we had
a spring company do that. Works great.

The industry calls them shunts AFAIK too even through they are series
resistance. Canadian Shunts is one company we used for 500 amp at 50
mV

Yes, we use the jumper shunts as well. Those may be seires or
parallel in circuit operation...

So, when you have a battery and a light bulb connected together, just
two components, is that a parallel or a series circuit ??

boB



BITD a \'meter shunt\' was a resistor whose tempco matched that of the
copper winding of your analogue meter movement, and whose resistance was
some convenient submultiple of the meter\'s resistance, like 1/99 to turn
a 1-mA meter into a 100-mA meter.

Nice not to have to worry about that anymore.

Cheers

Phil Hobbs

The manganin sheet stock that we bought had a zero TC around 60C,
which was the temperature of the heated block that we glued our shunts
to. One can also buy manganin that has its flat spot at room temp.

Punching and bending wrecked the TC, and annealing fixed it again.

Other alloys, like zerodur and something else, were much better but
hard to get.

We needed wideband current sensing to make PPM-precise pulses, and got
interesting eddy-current effects (looked like series inductance, make
voltage overshoots) from the shunt being flat against the aluminum
block. We found a fix for that.

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Wed, 07 Oct 2020 09:06:10 -0400, legg <legg@nospam.magma.ca> wrote:

On Tue, 6 Oct 2020 10:37:19 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:

I recall designing circuits for analog meters with current shunt resistors. In the last thirty years my measurements are all done by measuring voltage across series resistor. Is this resistor still referred to as a \"shunt\"? Even though it is no longer shunting current around a current meter, obsolete terminology often remains. An example is calling the AC-DC power supply in an LED replacement for a fluorescent lamp a \"ballast\".

Do you refer to the series current sense resistor a \"shunt\"?

Both terms are simple and quick expanations of a
component\'s function.

This practice is sometimes mis-used, but I think
you\'ve picked the wrong examples to shake your
stick at.

RL

We use a lot of shorthand terms that make language purists who don\'t
design things get all prissy.

Too bad.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Jeroen Belleman]

jlarkin@highlandsniptechnology.com wrote:
[Snip ...]

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.

Julien Bergoz, I\'m pretty much certain. Sadly, he passed away.

Jeroen Belleman

 

[server]

On Wed, 07 Oct 2020 17:28:16 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

jlarkin@highlandsniptechnology.com wrote:
[Snip ...]

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.


Julien Bergoz, I\'m pretty much certain. Sadly, he passed away.

Jeroen Belleman

Sad. He was a cool guy, sort of a French teddy bear/hurricane.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Jeroen Belleman]

On 2020-10-07 18:09, jlarkin@highlandsniptechnology.com wrote:

On Wed, 07 Oct 2020 17:28:16 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

jlarkin@highlandsniptechnology.com wrote:
[Snip ...]

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.


Julien Bergoz, I\'m pretty much certain. Sadly, he passed away.

Jeroen Belleman

Sad. He was a cool guy, sort of a French teddy bear/hurricane.

He was a colourful character. The first time I met him, he
was playing golf on the tiny front lawn of a hotel in
Frascati, Italy, sometime in the 1990s. He was the originator
of the \'Faraday Cup\', a reward for outstanding contributions
to the field of particle beam accelerator instrumentation. He
was enthusiastic about \"Goubeau lines\", some arrangement he
saw as useful for testing current transformers. I never quite
got the hang of what was so great about those.

His company, Bergoz Instrumentation, continues.

Jeroen Belleman

 

[server]

On Wednesday, 7 October 2020 16:06:09 UTC+1, jla...@highlandsniptechnology.com wrote:

The manganin sheet stock that we bought had a zero TC around 60C,
which was the temperature of the heated block that we glued our shunts
to. One can also buy manganin that has its flat spot at room temp.

Punching and bending wrecked the TC, and annealing fixed it again.

Other alloys, like zerodur and something else, were much better but
hard to get.

An electricity meter manufacturer I am familiar with use a manganin
strip electron beam welded to copper busbars to avoid some of
these issues - especially the avoidance of contamination and stress.

We needed wideband current sensing to make PPM-precise pulses, and got
interesting eddy-current effects (looked like series inductance, make
voltage overshoots) from the shunt being flat against the aluminum
block. We found a fix for that.

Narrow slots milled into the surface of the Al block or insulating
spacer?

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.

Yes, I used to anneal Mumetal in a hydrogen atmosphere. It made the
workshop manager very nervous.

John

 

[Ricketty C]

On Wednesday, October 7, 2020 at 2:18:01 PM UTC-4, jrwal...@gmail.com wrote:

On Wednesday, 7 October 2020 16:06:09 UTC+1, jla...@highlandsniptechnology.com wrote:

The manganin sheet stock that we bought had a zero TC around 60C,
which was the temperature of the heated block that we glued our shunts
to. One can also buy manganin that has its flat spot at room temp.

Punching and bending wrecked the TC, and annealing fixed it again.

Other alloys, like zerodur and something else, were much better but
hard to get.

An electricity meter manufacturer I am familiar with use a manganin
strip electron beam welded to copper busbars to avoid some of
these issues - especially the avoidance of contamination and stress.

We needed wideband current sensing to make PPM-precise pulses, and got
interesting eddy-current effects (looked like series inductance, make
voltage overshoots) from the shunt being flat against the aluminum
block. We found a fix for that.
Narrow slots milled into the surface of the Al block or insulating
spacer?

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.

Yes, I used to anneal Mumetal in a hydrogen atmosphere. It made the
workshop manager very nervous.

That\'s a little bit funny. A hydrogen atmosphere is not really any more dangerous than oxygen. We breath that stuff! It\'s when the two are mixed that you can have problems. I assume this would have been in a small volume?

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[Lasse Langwadt Christensen]

onsdag den 7. oktober 2020 kl. 20.27.27 UTC+2 skrev Ricketty C:

On Wednesday, October 7, 2020 at 2:18:01 PM UTC-4, jrwal...@gmail.com wrote:
On Wednesday, 7 October 2020 16:06:09 UTC+1, jla...@highlandsniptechnology.com wrote:

The manganin sheet stock that we bought had a zero TC around 60C,
which was the temperature of the heated block that we glued our shunts
to. One can also buy manganin that has its flat spot at room temp.

Punching and bending wrecked the TC, and annealing fixed it again.

Other alloys, like zerodur and something else, were much better but
hard to get.

An electricity meter manufacturer I am familiar with use a manganin
strip electron beam welded to copper busbars to avoid some of
these issues - especially the avoidance of contamination and stress.

We needed wideband current sensing to make PPM-precise pulses, and got
interesting eddy-current effects (looked like series inductance, make
voltage overshoots) from the shunt being flat against the aluminum
block. We found a fix for that.
Narrow slots milled into the surface of the Al block or insulating
spacer?

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.

Yes, I used to anneal Mumetal in a hydrogen atmosphere. It made the
workshop manager very nervous.

That\'s a little bit funny. A hydrogen atmosphere is not really any more dangerous than oxygen. We breath that stuff! It\'s when the two are mixed that you can have problems. I assume this would have been in a small volume?

hydrogen only takes a few uJ to ignite, it burns in any ratio with air from 4-75%, explodes in mixtures from 18-60%

 

[server]

On Wednesday, 7 October 2020 20:01:48 UTC+1, Lasse Langwadt Christensen wrote:

onsdag den 7. oktober 2020 kl. 20.27.27 UTC+2 skrev Ricketty C:
On Wednesday, October 7, 2020 at 2:18:01 PM UTC-4, jrwal...@gmail.com wrote:
On Wednesday, 7 October 2020 16:06:09 UTC+1, jla...@highlandsniptechnology.com wrote:

The manganin sheet stock that we bought had a zero TC around 60C,
which was the temperature of the heated block that we glued our shunts
to. One can also buy manganin that has its flat spot at room temp.

Punching and bending wrecked the TC, and annealing fixed it again.

Other alloys, like zerodur and something else, were much better but
hard to get.

An electricity meter manufacturer I am familiar with use a manganin
strip electron beam welded to copper busbars to avoid some of
these issues - especially the avoidance of contamination and stress.

We needed wideband current sensing to make PPM-precise pulses, and got
interesting eddy-current effects (looked like series inductance, make
voltage overshoots) from the shunt being flat against the aluminum
block. We found a fix for that.
Narrow slots milled into the surface of the Al block or insulating
spacer?

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.

Yes, I used to anneal Mumetal in a hydrogen atmosphere. It made the
workshop manager very nervous.

That\'s a little bit funny. A hydrogen atmosphere is not really any more dangerous than oxygen. We breath that stuff! It\'s when the two are mixed that you can have problems. I assume this would have been in a small volume?


hydrogen only takes a few uJ to ignite, it burns in any ratio with air from 4-75%, explodes in mixtures from 18-60%

I think the chamber volume was around 0.5l and the excess hydrogen was burned
off with a small flame outside the furnace. I thought it was safe.
I also used oxy-hydrogen in a miniature welding torch for welding platinum.
The torch had sapphire jets.

John

 

[Joerg]

On 10/7/20 8:08 AM, jlarkin@highlandsniptechnology.com wrote:

On Wed, 07 Oct 2020 09:06:10 -0400, legg <legg@nospam.magma.ca
wrote:

On Tue, 6 Oct 2020 10:37:19 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:

I recall designing circuits for analog meters with current shunt
resistors. In the last thirty years my measurements are all done
by measuring voltage across series resistor. Is this resistor
still referred to as a \"shunt\"? ...

Even though that would technically be a current sense resistor some
still call it shunt. Or in the UK \"shoont\"

... Even though it is no longer
shunting current around a current meter, obsolete terminology
often remains. An example is calling the AC-DC power supply in
an LED replacement for a fluorescent lamp a \"ballast\".

Same as some people call an electronic dimmer a rheostat. It\'s wrong but
everyone old enough knows what is meant.

Do you refer to the series current sense resistor a \"shunt\"?

Both terms are simple and quick expanations of a component\'s
function.

This practice is sometimes mis-used, but I think you\'ve picked the
wrong examples to shake your stick at.

RL

We use a lot of shorthand terms that make language purists who don\'t
design things get all prissy.

The first one I learned in industry was \"fudge factor\". Our professors
would have been disgusted.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Lasse Langwadt Christensen]

onsdag den 7. oktober 2020 kl. 21.09.26 UTC+2 skrev jrwal...@gmail.com:

On Wednesday, 7 October 2020 20:01:48 UTC+1, Lasse Langwadt Christensen wrote:
onsdag den 7. oktober 2020 kl. 20.27.27 UTC+2 skrev Ricketty C:
On Wednesday, October 7, 2020 at 2:18:01 PM UTC-4, jrwal...@gmail.com wrote:
On Wednesday, 7 October 2020 16:06:09 UTC+1, jla...@highlandsniptechnology.com wrote:

The manganin sheet stock that we bought had a zero TC around 60C,
which was the temperature of the heated block that we glued our shunts
to. One can also buy manganin that has its flat spot at room temp.

Punching and bending wrecked the TC, and annealing fixed it again.

Other alloys, like zerodur and something else, were much better but
hard to get.

An electricity meter manufacturer I am familiar with use a manganin
strip electron beam welded to copper busbars to avoid some of
these issues - especially the avoidance of contamination and stress.

We needed wideband current sensing to make PPM-precise pulses, and got
interesting eddy-current effects (looked like series inductance, make
voltage overshoots) from the shunt being flat against the aluminum
block. We found a fix for that.
Narrow slots milled into the surface of the Al block or insulating
spacer?

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.

Yes, I used to anneal Mumetal in a hydrogen atmosphere. It made the
workshop manager very nervous.

That\'s a little bit funny. A hydrogen atmosphere is not really any more dangerous than oxygen. We breath that stuff! It\'s when the two are mixed that you can have problems. I assume this would have been in a small volume?


hydrogen only takes a few uJ to ignite, it burns in any ratio with air from 4-75%, explodes in mixtures from 18-60%

I think the chamber volume was around 0.5l and the excess hydrogen was burned
off with a small flame outside the furnace. I thought it was safe.
I also used oxy-hydrogen in a miniature welding torch for welding platinum.
The torch had sapphire jets.

you can get a cheap Chinese electric, https://youtu.be/rD8XyicU_bo

 

[Ricketty C]

On Wednesday, October 7, 2020 at 3:01:48 PM UTC-4, Lasse Langwadt Christensen wrote:

onsdag den 7. oktober 2020 kl. 20.27.27 UTC+2 skrev Ricketty C:
On Wednesday, October 7, 2020 at 2:18:01 PM UTC-4, jrwal...@gmail.com wrote:
On Wednesday, 7 October 2020 16:06:09 UTC+1, jla...@highlandsniptechnology.com wrote:

The manganin sheet stock that we bought had a zero TC around 60C,
which was the temperature of the heated block that we glued our shunts
to. One can also buy manganin that has its flat spot at room temp.

Punching and bending wrecked the TC, and annealing fixed it again.

Other alloys, like zerodur and something else, were much better but
hard to get.

An electricity meter manufacturer I am familiar with use a manganin
strip electron beam welded to copper busbars to avoid some of
these issues - especially the avoidance of contamination and stress.

We needed wideband current sensing to make PPM-precise pulses, and got
interesting eddy-current effects (looked like series inductance, make
voltage overshoots) from the shunt being flat against the aluminum
block. We found a fix for that.
Narrow slots milled into the surface of the Al block or insulating
spacer?

Annealing is a black art. I knew a French guy who got the permeability
of metglas up to 1e6 by a secret annealing process.

Yes, I used to anneal Mumetal in a hydrogen atmosphere. It made the
workshop manager very nervous.

That\'s a little bit funny. A hydrogen atmosphere is not really any more dangerous than oxygen. We breath that stuff! It\'s when the two are mixed that you can have problems. I assume this would have been in a small volume?


hydrogen only takes a few uJ to ignite, it burns in any ratio with air from 4-75%, explodes in mixtures from 18-60%

It doesn\'t burn at 100% hydrogen. That is my point.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209