LED forward voltage drop with temperature

[habib]

Le 23/04/2020 à 16:06, jlarkin@highlandsniptechnology.com a Êcrit :

On Thu, 23 Apr 2020 12:39:28 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 22/04/2020 à 18:14, jlarkin@highlandsniptechnology.com a Êcrit :
On Wed, 22 Apr 2020 10:55:04 -0500, John S <Sophi.2@invalid.org
wrote:

LTSpice says that the forward voltage drop of LEDs have a positive
coefficient. That is contrary to my thinking and to my measurements.

Am I doing something wrong?

Probably depends on the current. Low current follows the diode
equation, ntc, but at high current voltage drop is dominated by the
ohmic component, with a positive TC. Basically all diodes do that.

Hi John,
https://www.dropbox.com/s/d4ntmq7fdzah69a/LED_Isrc_data.JPG?raw=1

Are you sure the current flowing through the LED is constant ? i.e.
temperature independent.
AFAIK current should be kept constant to evaluate voltage drift of Vf
over temperature.

Some basic math on your circuit would be nice to be explained. Please.

H

The LED current is set by the voltage drop across the 2K resistor. The
current TC is what I measured for the whole circuit.

Ok I see, MMBTH81 is not working at the same temperature than the LED,
is it ?

I also measured power supply sensitivity, which isn't bad at all.
Variation in power supply voltage directly (actually worse than
directly) changes the LED current. A tweak might null out power supply
sensitivity, but I had a good supply in my application.

There's no serious math here. There can't be without knowing a lot
more about the LEDs than is available. It was easier to build it and
test it.

You could Spice it to see the basic functionality, but I wouldn't
trust a simulation to predict TC.

Why not? Spice directives ".op" and ".step Temp 25 100" 1 would help to
figure out that TC is (always?) negative. AFAIK III/V components (e.g.
Gallium/Arsenide) have a negative TC coefficient.

It could certainly be better, with a thinfilm emitter resistor and
some more tweaking. It was good enough for my product so I moved on.
But there are much better circuits if one wants a super stable current
source. This was just sort of fun, and it glows in the dark.

In the dark as you say ;-)
Yeah resistors have few ppm/°C but the transistor has Vbe drift
-2.2mV/°C along with large drift of h21e intrinsic gain parameter

Transistor self-heating would be a problem if one wanted serious
stability. Base current too.

Thank you for the topic. H

 

[John Larkin]

On Thu, 23 Apr 2020 23:21:33 +0200, habib <h.bouazizviallet@free.fr>
wrote:

Le 23/04/2020 ŕ 22:50, John Larkin a écrit :
On Thu, 23 Apr 2020 22:05:27 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 23/04/2020 ŕ 16:06, jlarkin@highlandsniptechnology.com a écrit :
On Thu, 23 Apr 2020 12:39:28 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 22/04/2020 ŕ 18:14, jlarkin@highlandsniptechnology.com a écrit :
On Wed, 22 Apr 2020 10:55:04 -0500, John S <Sophi.2@invalid.org
wrote:

LTSpice says that the forward voltage drop of LEDs have a positive
coefficient. That is contrary to my thinking and to my measurements.

Am I doing something wrong?

Probably depends on the current. Low current follows the diode
equation, ntc, but at high current voltage drop is dominated by the
ohmic component, with a positive TC. Basically all diodes do that.

Hi John,
https://www.dropbox.com/s/d4ntmq7fdzah69a/LED_Isrc_data.JPG?raw=1

Are you sure the current flowing through the LED is constant ? i.e.
temperature independent.
AFAIK current should be kept constant to evaluate voltage drift of Vf
over temperature.

Some basic math on your circuit would be nice to be explained. Please.

H

The LED current is set by the voltage drop across the 2K resistor. The
current TC is what I measured for the whole circuit.
Ok I see, MMBTH81 is not working at the same temperature than the LED,
is it ?

It was just a little breadboard. The temps on all the parts were
similar.





I also measured power supply sensitivity, which isn't bad at all.
Variation in power supply voltage directly (actually worse than
directly) changes the LED current. A tweak might null out power supply
sensitivity, but I had a good supply in my application.

There's no serious math here. There can't be without knowing a lot
more about the LEDs than is available. It was easier to build it and
test it.

You could Spice it to see the basic functionality, but I wouldn't
trust a simulation to predict TC.

Why not? Spice directives ".op" and ".step Temp 25 100" 1 would help to
figure out that TC is (always?) negative. AFAIK III/V components (e.g.
Gallium/Arsenide) have a negative TC coefficient.

I don't have a Spice model of any of the LEDs that we have in stock.
I'd have to measure one over current and temperature and verify a
Spice model. It was easier to build the circuit. I'd want to do that
anyhow to verify the model.

The trick of this circuit is that the LED has more voltage drop than
the transistor be junction, but a similar absolute TC.



It could certainly be better, with a thinfilm emitter resistor and
some more tweaking. It was good enough for my product so I moved on.
But there are much better circuits if one wants a super stable current
source. This was just sort of fun, and it glows in the dark.
In the dark as you say ;-)

Light doesn't seem to matter. Makes sense. The LED is making a lot of
light, and it's very close to the LED.

Yeah resistors have few ppm/°C but the transistor has Vbe drift
-2.2mV/°C along with large drift of h21e intrinsic gain parameter

Exactly. The LED tempco mostly cancels the Vbe tempco.
Are you sure ? LED is not a silicon based component so I'm not sure they
have the same tempco.

It works.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Thu, 23 Apr 2020 22:05:27 +0200, habib <h.bouazizviallet@free.fr>
wrote:

Le 23/04/2020 ŕ 16:06, jlarkin@highlandsniptechnology.com a écrit :
On Thu, 23 Apr 2020 12:39:28 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 22/04/2020 ŕ 18:14, jlarkin@highlandsniptechnology.com a écrit :
On Wed, 22 Apr 2020 10:55:04 -0500, John S <Sophi.2@invalid.org
wrote:

LTSpice says that the forward voltage drop of LEDs have a positive
coefficient. That is contrary to my thinking and to my measurements.

Am I doing something wrong?

Probably depends on the current. Low current follows the diode
equation, ntc, but at high current voltage drop is dominated by the
ohmic component, with a positive TC. Basically all diodes do that.

Hi John,
https://www.dropbox.com/s/d4ntmq7fdzah69a/LED_Isrc_data.JPG?raw=1

Are you sure the current flowing through the LED is constant ? i.e.
temperature independent.
AFAIK current should be kept constant to evaluate voltage drift of Vf
over temperature.

Some basic math on your circuit would be nice to be explained. Please.

H

The LED current is set by the voltage drop across the 2K resistor. The
current TC is what I measured for the whole circuit.
Ok I see, MMBTH81 is not working at the same temperature than the LED,
is it ?

It was just a little breadboard. The temps on all the parts were
similar.

I also measured power supply sensitivity, which isn't bad at all.
Variation in power supply voltage directly (actually worse than
directly) changes the LED current. A tweak might null out power supply
sensitivity, but I had a good supply in my application.

There's no serious math here. There can't be without knowing a lot
more about the LEDs than is available. It was easier to build it and
test it.

You could Spice it to see the basic functionality, but I wouldn't
trust a simulation to predict TC.

Why not? Spice directives ".op" and ".step Temp 25 100" 1 would help to
figure out that TC is (always?) negative. AFAIK III/V components (e.g.
Gallium/Arsenide) have a negative TC coefficient.

I don't have a Spice model of any of the LEDs that we have in stock.
I'd have to measure one over current and temperature and verify a
Spice model. It was easier to build the circuit. I'd want to do that
anyhow to verify the model.

The trick of this circuit is that the LED has more voltage drop than
the transistor be junction, but a similar absolute TC.

It could certainly be better, with a thinfilm emitter resistor and
some more tweaking. It was good enough for my product so I moved on.
But there are much better circuits if one wants a super stable current
source. This was just sort of fun, and it glows in the dark.
In the dark as you say ;-)

Light doesn't seem to matter. Makes sense. The LED is making a lot of
light, and it's very close to the LED.

Yeah resistors have few ppm/°C but the transistor has Vbe drift
-2.2mV/°C along with large drift of h21e intrinsic gain parameter

Exactly. The LED tempco mostly cancels the Vbe tempco.

Transistor self-heating would be a problem if one wanted serious
stability. Base current too.

Thank you for the topic. H
--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[habib]

Le 23/04/2020 à 22:50, John Larkin a Êcrit :

On Thu, 23 Apr 2020 22:05:27 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 23/04/2020 à 16:06, jlarkin@highlandsniptechnology.com a Êcrit :
On Thu, 23 Apr 2020 12:39:28 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 22/04/2020 à 18:14, jlarkin@highlandsniptechnology.com a Êcrit :
On Wed, 22 Apr 2020 10:55:04 -0500, John S <Sophi.2@invalid.org
wrote:

LTSpice says that the forward voltage drop of LEDs have a positive
coefficient. That is contrary to my thinking and to my measurements.

Am I doing something wrong?

Probably depends on the current. Low current follows the diode
equation, ntc, but at high current voltage drop is dominated by the
ohmic component, with a positive TC. Basically all diodes do that.

Hi John,
https://www.dropbox.com/s/d4ntmq7fdzah69a/LED_Isrc_data.JPG?raw=1

Are you sure the current flowing through the LED is constant ? i.e.
temperature independent.
AFAIK current should be kept constant to evaluate voltage drift of Vf
over temperature.

Some basic math on your circuit would be nice to be explained. Please.

H

The LED current is set by the voltage drop across the 2K resistor. The
current TC is what I measured for the whole circuit.
Ok I see, MMBTH81 is not working at the same temperature than the LED,
is it ?

It was just a little breadboard. The temps on all the parts were
similar.





I also measured power supply sensitivity, which isn't bad at all.
Variation in power supply voltage directly (actually worse than
directly) changes the LED current. A tweak might null out power supply
sensitivity, but I had a good supply in my application.

There's no serious math here. There can't be without knowing a lot
more about the LEDs than is available. It was easier to build it and
test it.

You could Spice it to see the basic functionality, but I wouldn't
trust a simulation to predict TC.

Why not? Spice directives ".op" and ".step Temp 25 100" 1 would help to
figure out that TC is (always?) negative. AFAIK III/V components (e.g.
Gallium/Arsenide) have a negative TC coefficient.

I don't have a Spice model of any of the LEDs that we have in stock.
I'd have to measure one over current and temperature and verify a
Spice model. It was easier to build the circuit. I'd want to do that
anyhow to verify the model.

The trick of this circuit is that the LED has more voltage drop than
the transistor be junction, but a similar absolute TC.



It could certainly be better, with a thinfilm emitter resistor and
some more tweaking. It was good enough for my product so I moved on.
But there are much better circuits if one wants a super stable current
source. This was just sort of fun, and it glows in the dark.
In the dark as you say ;-)

Light doesn't seem to matter. Makes sense. The LED is making a lot of
light, and it's very close to the LED.

Yeah resistors have few ppm/°C but the transistor has Vbe drift
-2.2mV/°C along with large drift of h21e intrinsic gain parameter

Exactly. The LED tempco mostly cancels the Vbe tempco.

Are you sure ? LED is not a silicon based component so I'm not sure they
have the same tempco.

Transistor self-heating would be a problem if one wanted serious
stability. Base current too.

Thank you for the topic. H

 

[Phil Hobbs]

On 2020-04-23 17:21, habib wrote:

Le 23/04/2020 à 22:50, John Larkin a Êcrit :
On Thu, 23 Apr 2020 22:05:27 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 23/04/2020 à 16:06, jlarkin@highlandsniptechnology.com a Êcrit :
On Thu, 23 Apr 2020 12:39:28 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 22/04/2020 à 18:14, jlarkin@highlandsniptechnology.com a Êcrit :
On Wed, 22 Apr 2020 10:55:04 -0500, John S <Sophi.2@invalid.org
wrote:

LTSpice says that the forward voltage drop of LEDs have a positive
coefficient. That is contrary to my thinking and to my measurements.

Am I doing something wrong?

Probably depends on the current. Low current follows the diode
equation, ntc, but at high current voltage drop is dominated by the
ohmic component, with a positive TC. Basically all diodes do that.

Hi John,
https://www.dropbox.com/s/d4ntmq7fdzah69a/LED_Isrc_data.JPG?raw=1

Are you sure the current flowing through the LED is constant ? i.e.
temperature independent.
AFAIK current should be kept constant to evaluate voltage drift of Vf
over temperature.

Some basic math on your circuit would be nice to be explained. Please.

H

The LED current is set by the voltage drop across the 2K resistor. The
current TC is what I measured for the whole circuit.
Ok I see, MMBTH81 is not working at the same temperature than the LED,
is it ?

It was just a little breadboard. The temps on all the parts were
similar.





I also measured power supply sensitivity, which isn't bad at all.
Variation in power supply voltage directly (actually worse than
directly) changes the LED current. A tweak might null out power supply
sensitivity, but I had a good supply in my application.

There's no serious math here. There can't be without knowing a lot
more about the LEDs than is available. It was easier to build it and
test it.

You could Spice it to see the basic functionality, but I wouldn't
trust a simulation to predict TC.

Why not? Spice directives ".op" and ".step Temp 25 100" 1 would help to
figure out that TC is (always?) negative. AFAIK III/V components (e.g.
Gallium/Arsenide) have a negative TC coefficient.

I don't have a Spice model of any of the LEDs that we have in stock.
I'd have to measure one over current and temperature and verify a
Spice model. It was easier to build the circuit. I'd want to do that
anyhow to verify the model.

The trick of this circuit is that the LED has more voltage drop than
the transistor be junction, but a similar absolute TC.



It could certainly be better, with a thinfilm emitter resistor and
some more tweaking. It was good enough for my product so I moved on.
But there are much better circuits if one wants a super stable current
source. This was just sort of fun, and it glows in the dark.
In the dark as you say ;-)

Light doesn't seem to matter. Makes sense. The LED is making a lot of
light, and it's very close to the LED.

Yeah resistors have few ppm/°C but the transistor has Vbe drift
-2.2mV/°C along with large drift of h21e intrinsic gain parameter

Exactly. The LED tempco mostly cancels the Vbe tempco.
Are you sure ? LED is not a silicon based component so I'm not sure they
have the same tempco.

Different LEDs have slightly different tempcos. The bandgap goes up as
the lattice contracts, and the thermal effect goes the other way.

LEDs are direct-bandgap devices, so there are radiative as well as
nonradiative branches, which depend differently on the details of the
band shapes.

LEDs and lasers nearly always tune towards the blue at low temperatures,
but George's one tunes the other way.

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]

habib wrote:

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

Are you sure ? LED is not a silicon based component so I'm not sure they
have the same tempco.

**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.

Close to .004% per C.


..... Phil

 

[Pimpom]

On 4/24/2020 2:51 AM, habib wrote:

Le 23/04/2020 à 22:50, John Larkin a Êcrit :

Exactly. The LED tempco mostly cancels the Vbe tempco.

Are you sure ? LED is not a silicon based component so I'm not sure they
have the same tempco.

It's a fairly well known fact.

 

[habib]

Le 24/04/2020 à 00:58, Phil Allison a Êcrit :

habib wrote:

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


Are you sure ? LED is not a silicon based component so I'm not sure they
have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.

Close to .004% per C.
Sure although it is not "%" in that case.

Anyway we did not speak about metals, it was about tempco of IV-V
(silicon) and III-V materials.

H

.... Phil

 

[Phil Allison]

habib wrote:

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

Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Anyway we did not speak about metals,

** Yes we did and I mentioned alloys.

Anyhow the fact is YOU are 100% WRONG !!

FOAD


...... Phil

 

[Jeroen Belleman]

On 2020-04-24 11:20, Phil Allison wrote:

habib wrote:

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


Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error is being pedantic?

Interesting.

Jeroen Belleman

 

On Fri, 24 Apr 2020 02:20:53 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

habib wrote:

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


Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.


Anyway we did not speak about metals,


** Yes we did and I mentioned alloys.

Anyhow the fact is YOU are 100% WRONG !!

FOAD


..... Phil

LTDM


(learn to do math)



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[habib]

Le 24/04/2020 à 16:47, Phil Allison a Êcrit :

Jeroen Belleman wrote:

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



Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error


** Only a pedant would bother.

Someone like you.

Only "Allison-100%-wrong", allows himself speaking before thinking! I
suspect the Allison did not really understand what % really mean.

.... Phil

 

On Fri, 24 Apr 2020 17:35:36 +0200, habib <h.bouazizviallet@free.fr>
wrote:

Le 24/04/2020 ŕ 16:47, Phil Allison a écrit :
Jeroen Belleman wrote:

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



Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error


** Only a pedant would bother.

Someone like you.
Only "Allison-100%-wrong", allows himself speaking before thinking! I
suspect the Allison did not really understand what % really mean.

But he wasn't 100% wrong. He was 10,000% wrong.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Phil Allison]

Jeroen Belleman wrote:

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

Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error

** Only a pedant would bother.

Someone like you.


..... Phil

 

jlarkin@highlandsniptechnology.com wrote in
news:uu16afl44dgoojsqsbq22d0ogra2kq5drp@4ax.com:

But he wasn't 100% wrong. He was 10,000% wrong.

I was sure you were referring to Trump and his family of fuckups.

 

[habib]

Le 24/04/2020 à 17:40, jlarkin@highlandsniptechnology.com a Êcrit :

On Fri, 24 Apr 2020 17:35:36 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 à 16:47, Phil Allison a Êcrit :
Jeroen Belleman wrote:

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



Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error


** Only a pedant would bother.

Someone like you.
Only "Allison-100%-wrong", allows himself speaking before thinking! I
suspect the Allison did not really understand what % really mean.


But he wasn't 100% wrong. He was 10,000% wrong.

"Allison Coeff" --> 0.004% gives a coeff = 0.00004; 4.10-5

TC metals (Physics) = (approx.) 0.004; 4.10-3

An error magnitude of 100 between "Allison" and real Physics.

H
H

 

[John Larkin]

On Fri, 24 Apr 2020 18:16:14 +0200, habib <h.bouazizviallet@free.fr>
wrote:

Le 24/04/2020 ŕ 17:40, jlarkin@highlandsniptechnology.com a écrit :
On Fri, 24 Apr 2020 17:35:36 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 ŕ 16:47, Phil Allison a écrit :
Jeroen Belleman wrote:

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



Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error


** Only a pedant would bother.

Someone like you.
Only "Allison-100%-wrong", allows himself speaking before thinking! I
suspect the Allison did not really understand what % really mean.


But he wasn't 100% wrong. He was 10,000% wrong.

"Allison Coeff" --> 0.004% gives a coeff = 0.00004; 4.10-5

TC metals (Physics) = (approx.) 0.004; 4.10-3

An error magnitude of 100 between "Allison" and real Physics.

We need a new SI unit of wrongness, Allisons. We can't apply that to
the linux guy, since he is Always Wrong.

Obscure note: electrons conduct heat and electricity, which track. So
most metals and alloys are about 150,000 K/W per ohm.

I suppose then that thermal conductivity should have the same
temperature coefficient as electrical conductivity.

What's the thermal conductivity of a superconductor?

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[habib]

Le 24/04/2020 à 19:35, John Larkin a Êcrit :

On Fri, 24 Apr 2020 18:16:14 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 à 17:40, jlarkin@highlandsniptechnology.com a Êcrit :
On Fri, 24 Apr 2020 17:35:36 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 à 16:47, Phil Allison a Êcrit :
Jeroen Belleman wrote:

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



Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error


** Only a pedant would bother.

Someone like you.
Only "Allison-100%-wrong", allows himself speaking before thinking! I
suspect the Allison did not really understand what % really mean.


But he wasn't 100% wrong. He was 10,000% wrong.

"Allison Coeff" --> 0.004% gives a coeff = 0.00004; 4.10-5

TC metals (Physics) = (approx.) 0.004; 4.10-3

An error magnitude of 100 between "Allison" and real Physics.


We need a new SI unit of wrongness, Allisons. We can't apply that to
the linux guy, since he is Always Wrong.
from now we will name it so, Allison's SI

Obscure note: electrons conduct heat and electricity, which track. So
most metals and alloys are about 150,000 K/W per ohm.

Thermal resistivity 150 000 °K/W for a Allison metal, this make sense
with Allison's SI

I suppose then that thermal conductivity should have the same
temperature coefficient as electrical conductivity.

What's the thermal conductivity of a superconductor?

I guess W/K.m is about 10e5 or 10e15 or something like that for a supra
conductor material, Sure that Allison has another figure based on own SI ?

H
>

 

[Ricky C]

On Friday, April 24, 2020 at 1:35:41 PM UTC-4, John Larkin wrote:

On Fri, 24 Apr 2020 18:16:14 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 à 17:40, jlarkin@highlandsniptechnology.com a Êcrit :
On Fri, 24 Apr 2020 17:35:36 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 à 16:47, Phil Allison a Êcrit :
Jeroen Belleman wrote:

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


Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

Silver, copper, gold, aluminium, magnesium, tungsten, zinc, nickel, tin, iron, platinum, mild steel, lead plus some alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error


** Only a pedant would bother.

Someone like you.
Only "Allison-100%-wrong", allows himself speaking before thinking! I
suspect the Allison did not really understand what % really mean.


But he wasn't 100% wrong. He was 10,000% wrong.

"Allison Coeff" --> 0.004% gives a coeff = 0.00004; 4.10-5

TC metals (Physics) = (approx.) 0.004; 4.10-3

An error magnitude of 100 between "Allison" and real Physics.


We need a new SI unit of wrongness, Allisons. We can't apply that to
the linux guy, since he is Always Wrong.

Obscure note: electrons conduct heat and electricity, which track. So
most metals and alloys are about 150,000 K/W per ohm.

I suppose then that thermal conductivity should have the same
temperature coefficient as electrical conductivity.

What's the thermal conductivity of a superconductor?

Whoever came up with a name for water wasn't a fish. Superconductors don't ask questions about conductivity. Superfluids have no thermal resistance and so ask no questions about the flow of heat.

If people were superfluid to determine if I had a fever you would take your own temperature.

--

Rick C.

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

 

[bitrex]

On 4/24/2020 5:08 PM, bitrex wrote:

On 4/24/2020 1:35 PM, John Larkin wrote:
On Fri, 24 Apr 2020 18:16:14 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 à 17:40, jlarkin@highlandsniptechnology.com a Êcrit :
On Fri, 24 Apr 2020 17:35:36 +0200, habib <h.bouazizviallet@free.fr
wrote:

Le 24/04/2020 à 16:47, Phil Allison a Êcrit :
Jeroen Belleman wrote:

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



Are you sure ? LED is not a silicon based component so I'm not
sure they> have the same tempco.



**FYI:

      Silver, copper, gold, aluminium, magnesium, tungsten,
zinc, nickel, tin, iron, platinum, mild steel, lead plus some
alloys ALL have the same positive tempco of resistance.


Close to .004% per C.

Sure although it is not "%" in that case.

** Pedant.

Pointing out a factor of hundred error


** Only a pedant would bother.
      Someone like you.
Only "Allison-100%-wrong", allows himself speaking before thinking! I
suspect the Allison did not really understand what % really mean.


But he wasn't 100% wrong. He was 10,000% wrong.

"Allison Coeff" --> 0.004% gives a coeff = 0.00004; 4.10-5

TC metals (Physics) = (approx.) 0.004; 4.10-3

An error magnitude of 100 between "Allison" and real Physics.


We need a new SI unit of wrongness, Allisons. We can't apply that to
the linux guy, since he is Always Wrong.

Obscure note: electrons conduct heat and electricity, which track. So
most metals and alloys are about 150,000 K/W per ohm.

I suppose then that thermal conductivity should have the same
temperature coefficient as electrical conductivity.

What's the thermal conductivity of a superconductor?


Low-temperature metallic superconductors are lousy thermal conductors;
Pauli exclusion principle, almost all of the lower-energy states are
filled and there aren't many empty states between kT and the energy gap
for the higher energy ones to move into, either.

If the electrons are all bound up then thermal conduction can only be
thru the lattice phonons but that's an order of magnitude less strong an
effect than electron conduction in most metals.