On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?


NT

On Thu, 21 Dec 2017 08:44:21 -0800 (PST), wrote:

On Thursday, 21 December 2017 14:25:28 UTC, whisky-dave wrote:
On Thursday, 21 December 2017 11:18:38 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils.

What temperature rating capacitor would you expect to be fitted and why would it
'boil' at 105 deg C?

There's no evidence they'll boil but the electrolyte will dry out the higher the temperature, the 105 is the maxium working temeprature and at that they are gurenteed to last say 1000 or 2000 hours as a minium, you can get 130C caps if really are running at high temps.

Dave is scientifically thorough, he doesn't just take your word for things, he requires evidence that water boils.


And it never does in his labs, not enough power. ;-)

Cheers, T i m

wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

In article 4feda002-b65c-4bf0-b8bd-ba2ea1c70a22
@googlegroups.com, says...


There are 3 derating lines shown. How do you make sense of them?


To honest, I can't!

None of them seem to be applicable to the resistors shown. The
spec says derate to zero at 250°C (from 70°C) but the 70°C
derating curve in that graph has its zero point at 300°C!

However, there is a gentleman in New Delhi who should be able
to answer your question if you wish to purue it - see the
Contact Us page.

Why not give him a bell and report back?

--

Terry

---
This email has been checked for viruses by AVG.
http://www.avg.com

In article ,
whisky-dave writes:
On Thursday, 21 December 2017 11:18:38 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:
=20
The CFL power supply will be stone dead at 105C when the electrolyte in=
=20
the PSU capacitors boils.=20
=20
What temperature rating capacitor would you expect to be fitted and why w=
ould it
'boil' at 105 deg C?

There's no evidence they'll boil but the electrolyte will dry out the highe=
r the temperature, the 105 is the maxium working temeprature and at that th=
ey are gurenteed to last say 1000 or 2000 hours as a minium, you can get 13=
0C caps if really are running at high temps.

They pretty well all use 105C, 5,000 or 10,000hr capacitors.

They often end up running hotter than this in enclosed fittings,
which will reduce the life of this capacitor, but control gear
failure is very rarely due to this capacitor failing (I've only
seen one case, and it didn't stop the lamp working - just went
dimmer). Early failure of control gear is more commonly one of
the MOSFETs going pop.

Note that some control gear deliberately sacrifices itself when
it detects the tube is worn out, to prevent it continuing to
operate a dead tube as a cold cathode tube which (ironically)
risks the tube overheating and setting light to something or
the glass breaking. This is crude and relies on a fusible
resistor burning out when the tube voltage and power consumption
increase in cold cathode mode. (Reusable control gear detects
this by noticing the tube turn into a partial rectifier when
the emission coating is all gone from one end, and shuts down
temporarily until the tube is replaced.)

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other MikeÂ* wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his point.

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but the
3rd graph has me stumped apart from the graph ending at 250C. I then
note 250C is the "Derate to Zero" spec. Why then do the first 2 indicate
a zero rating at 300C?

Perhaps you can care enlighten us? Hopefully in a non-belligerent,
knowledgable manner.

On Friday, 22 December 2017 13:06:32 UTC, Fredxx wrote:
On 22/12/2017 01:24, Rod Speed wrote:
tabbypurr wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other MikeÂ* wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:


Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his point.

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but the
3rd graph has me stumped apart from the graph ending at 250C. I then
note 250C is the "Derate to Zero" spec. Why then do the first 2 indicate
a zero rating at 300C?

Perhaps you can care enlighten us? Hopefully in a non-belligerent,
knowledgable manner.

I think the only answer is that the necessary information is not there. But 2 of the lines at least do show 100% of specified P_diss only available at unusually low temps. However I was overly quick initially to just believe what the graph showed, evidently the whole thing doesn't add up.

FWIW silicon devices are often specced to give claimed P_diss at unrealistic case temps, I wouldn't assume any better for other components.


NT

On 22/12/17 15:18, wrote:
FWIW silicon devices are often specced to give claimed P_diss at unrealistic case temps, I wouldn't assume any better for other components.

Indeed. But that is not a true usbale 'rating' - that is a measure of
chip to case thermal conductivity.

There is no other way to specify it for a power transistor bolted to a
heat sink of unknowable thermal resistance in an equally unknowable
ambient airflow.



--
Socialism is the philosophy of failure, the creed of ignorance and the
gospel of envy.

Its inherent virtue is the equal sharing of misery.

Winston Churchill

"Fredxx" wrote in message
news
On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not understand
the 3 lines, then I had a closer look and I can see his point.

Not on his silly claim that they only have their rated power at
-100C he doesnt. The table clearly shows they have that at 70C.

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but the
3rd graph has me stumped apart from the graph ending at 250C. I then note
250C is the "Derate to Zero" spec. Why then do the first 2 indicate a zero
rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his original silly
claim.

On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news
On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other MikeÂ* wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his point.

Not on his silly claim that they only have their rated power at
-100C he doesnt.Â* The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown. How do
you make sense of them?"

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but
the 3rd graph has me stumped apart from the graph ending at 250C. I
then note 250C is the "Derate to Zero" spec. Why then do the first 2
indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his original
silly claim.

The only silly claim I saw was "For temps over 70C".

wrote in message
...
On Friday, 22 December 2017 13:06:32 UTC, Fredxx wrote:
On 22/12/2017 01:24, Rod Speed wrote:
tabbypurr wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:


Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his point.

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but the
3rd graph has me stumped apart from the graph ending at 250C. I then
note 250C is the "Derate to Zero" spec. Why then do the first 2 indicate
a zero rating at 300C?

Perhaps you can care enlighten us? Hopefully in a non-belligerent,
knowledgable manner.

I think the only answer is that the necessary information is not there.

It likely is when you finally see what he meant.

But 2 of the lines at least do show 100% of specified P_diss
only available at unusually low temps. However I was overly
quick initially to just believe what the graph showed,

And ignored the table below it which explicitly
says that the power dissipations are at 70C

evidently the whole thing doesn't add up.

It likely is when you finally see what he meant.

FWIW silicon devices are often specced to give claimed P_diss at
unrealistic
? case temps, I wouldn't assume any better for other components.

Makes no sense to do that with a power resistor.

"Fredxx" wrote in message
news
On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news
On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

Not on his silly claim that they only have their rated power at
-100C he doesnt. The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown. How do you
make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but the
3rd graph has me stumped apart from the graph ending at 250C. I then
note 250C is the "Derate to Zero" spec. Why then do the first 2 indicate
a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his original
silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

On Friday, 22 December 2017 19:56:33 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Friday, 22 December 2017 13:06:32 UTC, Fredxx wrote:
On 22/12/2017 01:24, Rod Speed wrote:
tabbypurr wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:


Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his point.

On Friday, 22 December 2017 17:32:13 UTC, The Natural Philosopher wrote:
On 22/12/17 15:18, tabbypurr wrote:

FWIW silicon devices are often specced to give claimed P_diss at unrealistic case temps, I wouldn't assume any better for other components.

Indeed. But that is not a true usbale 'rating' - that is a measure of
chip to case thermal conductivity.

of course

There is no other way to specify it for a power transistor bolted to a
heat sink of unknowable thermal resistance in an equally unknowable
ambient airflow.

Of course there's another way, give a power figure for realistic conditions. It's marketing innit.


NT

wrote in message
...
On Friday, 22 December 2017 19:56:33 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Friday, 22 December 2017 13:06:32 UTC, Fredxx wrote:
On 22/12/2017 01:24, Rod Speed wrote:
tabbypurr wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:


Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but
the
3rd graph has me stumped apart from the graph ending at 250C. I then
note 250C is the "Derate to Zero" spec. Why then do the first 2
indicate
a zero rating at 300C?

Perhaps you can care enlighten us? Hopefully in a non-belligerent,
knowledgable manner.

I think the only answer is that the necessary information is not there.

It likely is when you finally see what he meant.

But 2 of the lines at least do show 100% of specified P_diss
only available at unusually low temps. However I was overly
quick initially to just believe what the graph showed,

And ignored the table below it which explicitly
says that the power dissipations are at 70C

ah! that wasn't displayed, it was covered up by something stupid

evidently the whole thing doesn't add up.

It likely is when you finally see what he meant.

FWIW silicon devices are often specced to give claimed P_diss at
unrealistic
? case temps, I wouldn't assume any better for other components.

Makes no sense to do that with a power resistor.

it makes the exact same sense that it does to do it with transistors,

Nope. Its trivial to do ceramic power resistors, much harder to do power
semis.

it's marketing brag, it gets people looking at the part instead of someone
else's.

Doesnt happen enough to matter with ceramic power resistors.

reams of your mindless silly **** flushed where it belongs

On 22/12/2017 20:16, Rod Speed wrote:


"Fredxx" wrote in message
news
On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other MikeÂ* wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

Not on his silly claim that they only have their rated power at
-100C he doesnt.Â* The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown. How do
you make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but
the 3rd graph has me stumped apart from the graph ending at 250C. I
then note 250C is the "Derate to Zero" spec. Why then do the first 2
indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his
original silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

I simply knew you had posted above your paygrade and would resort to abuse.

As usual, when you're too stupid and misunderstand a simple graph, you
have to resort to your typical throwing of your rattle out of a pram.

Go on reply, and remove all my post, with another example of a lost
argument.

Once again, you demonstrate you're not very bright.

On 23/12/2017 00:35, Rod Speed wrote:


wrote in message
...
On Friday, 22 December 2017 19:56:33 UTC, Rod SpeedÂ* wrote:
tabbypurr wrote in message
...
On Friday, 22 December 2017 13:06:32 UTC, FredxxÂ* wrote:
On 22/12/2017 01:24, Rod Speed wrote:
tabbypurr wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:


Some power resistors are only specified for claimed power

dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating,
but the
3rd graph has me stumped apart from the graph ending at 250C. I then
note 250C is the "Derate to Zero" spec. Why then do the first 2
indicate
a zero rating at 300C?

Perhaps you can care enlighten us? Hopefully in a non-belligerent,
knowledgable manner.

I think the only answer is that the necessary information is not
there.

It likely is when you finally see what he meant.

But 2 of the lines at least do show 100% of specified P_diss
only available at unusually low temps. However I was overly
quick initially to just believe what the graph showed,

And ignored the table below it which explicitly
says that the power dissipations are at 70C

ah! that wasn't displayed, it was covered up by something stupid

evidently the whole thing doesn't add up.

It likely is when you finally see what he meant.

FWIW silicon devices are often specced to give claimed P_diss at
unrealistic
? case temps, I wouldn't assume any better for other components.

Makes no sense to do that with a power resistor.

it makes the exact same sense that it does to do it with transistors,

Nope. Its trivial to do ceramic power resistors, much harder to do power
semis.

Nope, they might be different issues, but the zero rated temperature is
the maximum working temperature. The rest is down to thermal resistance.

it's marketing brag, it gets people looking at the part instead of
someone else's.

Doesnt happen enough to matter with ceramic power resistors.

reams of your mindless silly **** flushed where it belongs

As typical, you are demonstrating you don't have a clue.

Fredxx wrote:
On 23/12/2017 00:35, Rod Speed wrote:


Doesnt happen enough to matter with ceramic power resistors.

reams of your mindless silly **** flushed where it belongs

As typical, you are demonstrating you don't have a clue.

He knows exactly what hes doing and saying, hes trolling you.

Tim

--
Please don't feed the trolls

"Fredxx" wrote in message
news
On 22/12/2017 20:16, Rod Speed wrote:


"Fredxx" wrote in message
news
On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

Not on his silly claim that they only have their rated power at
-100C he doesnt. The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown. How do
you make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but
the 3rd graph has me stumped apart from the graph ending at 250C. I
then note 250C is the "Derate to Zero" spec. Why then do the first 2
indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his original
silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

I simply knew you had posted above your paygrade and would resort to
abuse.

Corse you never ever do anything like that yourself,
eh you pathetic excuse for a bull**** artist ?

As usual, when you're too stupid and misunderstand a simple graph,

Dont need to on when pointing out how stupid the original claim was.

reams of your **** flushed where it belongs

"Fredxx" wrote in message
news
On 23/12/2017 00:35, Rod Speed wrote:


wrote in message
...
On Friday, 22 December 2017 19:56:33 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Friday, 22 December 2017 13:06:32 UTC, Fredxx wrote:
On 22/12/2017 01:24, Rod Speed wrote:
tabbypurr wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:


Some power resistors are only specified for claimed power

dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating,
but the
3rd graph has me stumped apart from the graph ending at 250C. I then
note 250C is the "Derate to Zero" spec. Why then do the first 2
indicate
a zero rating at 300C?

Perhaps you can care enlighten us? Hopefully in a non-belligerent,
knowledgable manner.

I think the only answer is that the necessary information is not
there.

It likely is when you finally see what he meant.

But 2 of the lines at least do show 100% of specified P_diss
only available at unusually low temps. However I was overly
quick initially to just believe what the graph showed,

And ignored the table below it which explicitly
says that the power dissipations are at 70C

ah! that wasn't displayed, it was covered up by something stupid

evidently the whole thing doesn't add up.

It likely is when you finally see what he meant.

FWIW silicon devices are often specced to give claimed P_diss at
unrealistic
? case temps, I wouldn't assume any better for other components.

Makes no sense to do that with a power resistor.

it makes the exact same sense that it does to do it with transistors,

Nope. Its trivial to do ceramic power resistors, much harder to do power
semis.

Nope,

Yep.

they might be different issues,

There are no issues with ceramic resistors, ****wit.

but the zero rated temperature is the maximum working temperature. The
rest is down to thermal resistance.

Irrelevant to whether is any need to play silly buggers with the temperate
at which it delivers on its specs with ceramic resistors, ****wit.

it's marketing brag, it gets people looking at the part instead of
someone else's.

Doesnt happen enough to matter with ceramic power resistors.

reams of your mindless silly **** flushed where it belongs

On 22/12/17 23:35, wrote:
On Friday, 22 December 2017 17:32:13 UTC, The Natural Philosopher wrote:
On 22/12/17 15:18, tabbypurr wrote:

FWIW silicon devices are often specced to give claimed P_diss at unrealistic case temps, I wouldn't assume any better for other components.

Indeed. But that is not a true usbale 'rating' - that is a measure of
chip to case thermal conductivity.

of course

There is no other way to specify it for a power transistor bolted to a
heat sink of unknowable thermal resistance in an equally unknowable
ambient airflow.

Of course there's another way, give a power figure for realistic conditions. It's marketing innit.


You really have lost te plot you know.

What exactly are 'realistic conditions?
A TO3 bolted to a PCB? To a 3" square finned heatsink? To a massive fan
blown heatsink?

You are one of those ignorant people who insists on simple answers when
there are none.

The spec sheet will tell you 5W in free air at 25C and 150W at a CASE
temperature of 25C

As a designer, you then need to look at the thermal resistance of
suitable heat sinks and determine what actual dissipation you can get
away with in a hot steamy discotheque in Botswana....;-)



--
Climate Change: Socialism wearing a lab coat.

On Saturday, 23 December 2017 11:43:57 UTC, The Natural Philosopher wrote:
On 22/12/17 23:35, tabbypurr wrote:
On Friday, 22 December 2017 17:32:13 UTC, The Natural Philosopher wrote:
On 22/12/17 15:18, tabbypurr wrote:

FWIW silicon devices are often specced to give claimed P_diss at unrealistic case temps, I wouldn't assume any better for other components.

Indeed. But that is not a true usbale 'rating' - that is a measure of
chip to case thermal conductivity.

of course

There is no other way to specify it for a power transistor bolted to a
heat sink of unknowable thermal resistance in an equally unknowable
ambient airflow.

Of course there's another way, give a power figure for realistic conditions. It's marketing innit.


You really have lost te plot you know.

What exactly are 'realistic conditions?
A TO3 bolted to a PCB? To a 3" square finned heatsink? To a massive fan
blown heatsink?

all of those happen, the middle one being the more common.

You are one of those ignorant people who insists on simple answers when
there are none.

er, really? lol

The spec sheet will tell you 5W in free air at 25C and 150W at a CASE
temperature of 25C

As a designer, you then need to look at the thermal resistance of
suitable heat sinks and determine what actual dissipation you can get
away with in a hot steamy discotheque in Botswana....;-)

yeees...
I see you have no valid point with this.


NT

On 23/12/2017 09:13, Rod Speed wrote:


"Fredxx" wrote in message
news
On 22/12/2017 20:16, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from
over-heating.

Some power resistors are only specified for claimed power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

Not on his silly claim that they only have their rated power at
-100C he doesnt.Â* The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown. How
do you make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be
potential increased rating at lower temperatures based on the 70C
rating, but the 3rd graph has me stumped apart from the graph
ending at 250C. I then note 250C is the "Derate to Zero" spec. Why
then do the first 2 indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his
original silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

I simply knew you had posted above your paygrade and would resort to
abuse.

Corse you never ever do anything like that yourself,
eh you pathetic excuse for a bull**** artist ?

As usual, when you're too stupid and misunderstand a simple graph,

Dont need to on when pointing out how stupid the original claim was.

reams of your **** flushed where it belongs

Quite, the original claim was "Thats what they are for, temps other
than 70C".

"Fredxx" wrote in message
news
On 23/12/2017 09:13, Rod Speed wrote:


"Fredxx" wrote in message
news
On 22/12/2017 20:16, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from
over-heating.

Some power resistors are only specified for claimed power

dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

Not on his silly claim that they only have their rated power at
-100C he doesnt. The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown. How do
you make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be potential
increased rating at lower temperatures based on the 70C rating, but
the 3rd graph has me stumped apart from the graph ending at 250C. I
then note 250C is the "Derate to Zero" spec. Why then do the first 2
indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his
original silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

I simply knew you had posted above your paygrade and would resort to
abuse.

Corse you never ever do anything like that yourself,
eh you pathetic excuse for a bull**** artist ?

As usual, when you're too stupid and misunderstand a simple graph,

Dont need to on when pointing out how stupid the original claim was.

reams of your **** flushed where it belongs

Quite, the original claim was "Thats what they are for, temps other than
70C".

The original claim was that you only get the rated power dissipation
at -100C

That is a bare faced pig ignorant lie.

On 24/12/2017 00:51, Rod Speed wrote:


"Fredxx" wrote in message
news
On 23/12/2017 09:13, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 20:16, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from
over-heating.

Some power resistors are only specified for claimed
power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see
his point.

Not on his silly claim that they only have their rated power at
-100C he doesnt.Â* The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown.
How do you make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be
potential increased rating at lower temperatures based on the
70C rating, but the 3rd graph has me stumped apart from the
graph ending at 250C. I then note 250C is the "Derate to Zero"
spec. Why then do the first 2 indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his
original silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

I simply knew you had posted above your paygrade and would resort to
abuse.

Corse you never ever do anything like that yourself,
eh you pathetic excuse for a bull**** artist ?

As usual, when you're too stupid and misunderstand a simple graph,

Dont need to on when pointing out how stupid the original claim was.

reams of your **** flushed where it belongs

Quite, the original claim was "Thats what they are for, temps other
than 70C".

The original claim was that you only get the rated power dissipation at
-100C

That is a bare faced pig ignorant lie

The only lie is you were replying to "There are 3 derating lines shown.
How do you make sense of them?" with "Thats what they are for, temps
other than 70C".

You seem to be in denial, once more.

"Fredxx" wrote in message
news
On 24/12/2017 00:51, Rod Speed wrote:


"Fredxx" wrote in message
news
On 23/12/2017 09:13, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 20:16, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 18:07, Rod Speed wrote:


"Fredxx" wrote in message
news On 22/12/2017 01:24, Rod Speed wrote:


wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry Casey wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from
over-heating.

Some power resistors are only specified for claimed
power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see his
point.

Not on his silly claim that they only have their rated power at
-100C he doesnt. The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown. How
do you make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be
potential increased rating at lower temperatures based on the 70C
rating, but the 3rd graph has me stumped apart from the graph
ending at 250C. I then note 250C is the "Derate to Zero" spec. Why
then do the first 2 indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his
original silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

I simply knew you had posted above your paygrade and would resort to
abuse.

Corse you never ever do anything like that yourself,
eh you pathetic excuse for a bull**** artist ?

As usual, when you're too stupid and misunderstand a simple graph,

Dont need to on when pointing out how stupid the original claim was.

reams of your **** flushed where it belongs

Quite, the original claim was "Thats what they are for, temps other
than 70C".

The original claim was that you only get the rated power dissipation
at -100C

That is a bare faced pig ignorant lie

The only lie is you were replying to "There are 3 derating lines shown.
How do you make sense of them?" with "Thats what they are for, temps
other than 70C".

Thats not a lie, that what the chart is for.

You seem to be in denial, once more.

You are proving you never had a clue, as always.

On Sunday, 24 December 2017 01:40:00 UTC, Fredxx wrote:
On 24/12/2017 00:51, Rod Speed wrote:
"Fredxx" wrote in message
news
On 23/12/2017 09:13, Rod Speed wrote:
"Fredxx" wrote in message
news On 22/12/2017 20:16, Rod Speed wrote:
"Fredxx" wrote in message
news On 22/12/2017 18:07, Rod Speed wrote:
"Fredxx" wrote in message
news On 22/12/2017 01:24, Rod Speed wrote:
tabbypurr wrote in message
...
On Thursday, 21 December 2017 17:34:30 UTC, Terry CaseyÂ* wrote:
In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, tabbypurr says...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike
wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

Some power resistors are only specified for claimed
power
dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!

There are 3 derating lines shown. How do you make sense of them?

For temps over 70C.

I have to admit I initially thought tabbypurr was a prat to not
understand the 3 lines, then I had a closer look and I can see
his point.

Not on his silly claim that they only have their rated power at
-100C he doesnt.Â* The table clearly shows they have that at 70C.

The claim you replied to was "There are 3 derating lines shown.
How do you make sense of them?"

Thats what they are for, temps other than 70C

I might interpret the second line down on the graph to be
potential increased rating at lower temperatures based on the
70C rating, but the 3rd graph has me stumped apart from the
graph ending at 250C. I then note 250C is the "Derate to Zero"
spec. Why then do the first 2 indicate a zero rating at 300C?

Yes, that graph is a mess, but thats a separate issue to his
original silly claim.

The only silly claim I saw was "For temps over 70C".

You never could bull**** your way out of a wet paper bag.

I simply knew you had posted above your paygrade and would resort to
abuse.

Corse you never ever do anything like that yourself,
eh you pathetic excuse for a bull**** artist ?

As usual, when you're too stupid and misunderstand a simple graph,

Dont need to on when pointing out how stupid the original claim was.

reams of your **** flushed where it belongs

Quite, the original claim was "Thats what they are for, temps other
than 70C".

The original claim was that you only get the rated power dissipation at
-100C

That is a bare faced pig ignorant lie

The only lie is you were replying to "There are 3 derating lines shown.
How do you make sense of them?" with "Thats what they are for, temps
other than 70C".

You seem to be in denial, once more.

I made a mistake in not reading the whole document to see that it contradicted itself. But Rod's reply was.... well, can one find words for such a description of a graph with temp on one axis?


NT