Magnus wrote:
Having 1-10 kW per rack is not uncommon these days, so
forced convection needs to be done
That and more. A fully loaded 42U rack of HP C-class blades runs 8 kW idle and
peaks at 24 kW.
This can be air cooled (easily) in a properly designed and commissioned
run-of-the-mill rais
In message , Mark Sims writes:
>
>Many failed electrolytic caps on PC motherboards and in PC power supplies
>can be traced to a case of industrial espionage gone wrong. [...]
While this tale is true, the fact is that even without incompetence,
electrolytics suck.
--
Poul-Henning Kamp | UN
Poul-Henning Kamp wrote:
> It is worth pointing out that a very large fraction of all electronics
> failures are not semiconductors but electrolytic capacitors.
>
> People are often astonished when I tell them, that a "long life"
> electrolytic capacitor is one which will last one year at its rated
Mark Sims skrev:
The power dissipated in a modern CPU chip (watts per sq cm) far exceeds that of
a cooking hotplate. There are some videos on YouTube showing CPU's literally
exploding when they loose cooling for just a short time. ECL is a rather
chilly iceberg in comparison...
The Cray-1,
Poul-Henning Kamp skrev:
In message <4a170da2.3080...@rubidium.dyndns.org>, Magnus Danielson writes:
Hal Murray skrev:
There are being books written about this. One that I have found being a
fairly short but useful one is the AT&T Reliability Manual.
It is worth pointing out that a very lar
In message <971f24636bd13158d9fe412ec6c9c885.squir...@webmail.sonic.net>, "Rick
Karlquist" writes:
>The old photos of Len Cutler watching the airline porters carrying
>the clock up the stairs to the plane give the impression that
>the airline was honored to be asked to participate.
According to
In message <4a170da2.3080...@rubidium.dyndns.org>, Magnus Danielson writes:
>Hal Murray skrev:
>There are being books written about this. One that I have found being a
>fairly short but useful one is the AT&T Reliability Manual.
It is worth pointing out that a very large fraction of all electron
M. Warner Losh wrote:
> In message: <20090522185851.4137db...@ip-64-139-1-69.sjc.megapath.net>
> Hal Murray writes:
> :
> : rich...@karlquist.com said:
>> : Did you have any trouble convincing the airlines and/or FAA that it was
> safe
> : to take an atomic clock on a plane?
I never h
Hal Murray wrote:
The reason for the fans is to prevent premature failures of the
silicon devices due to thermal degradation. The life of a silicon
chip is halved for every 10C temperature increase, more or less.
I was going to make a similar comment, but got sidetracked poking around
google.
Hal Murray skrev:
The reason for the fans is to prevent premature failures of the
silicon devices due to thermal degradation. The life of a silicon
chip is halved for every 10C temperature increase, more or less.
I was going to make a similar comment, but got sidetracked poking around
google.
In message: <20090522185851.4137db...@ip-64-139-1-69.sjc.megapath.net>
Hal Murray writes:
:
: rich...@karlquist.com said:
: > First of all, the 5071A has to be able to run on a battery, so you can
: > do the flying clock experiment.
:
: Did you have any trouble convincing the airline
> The reason for the fans is to prevent premature failures of the
> silicon devices due to thermal degradation. The life of a silicon
> chip is halved for every 10C temperature increase, more or less.
I was going to make a similar comment, but got sidetracked poking around
google. I didn't fin
Hi!
Regarding the comments below on the 5370: there are always two
questions with temperature: meeting spec and reliability. Instruments
vary as to which is a bigger issue. Some have temperature
proof measurement techniques that will work virtually until
something burns up, so you can get lu
rich...@karlquist.com said:
> First of all, the 5071A has to be able to run on a battery, so you can
> do the flying clock experiment.
Did you have any trouble convincing the airlines and/or FAA that it was safe
to take an atomic clock on a plane?
I'd be more worried about the big batteries tha
In message , Mark Sims writes:
>I was rather surprised to see that, if anything, the internal jitter went
> down a couple of picoseconds
That could easily be reduced microphonics in the OCXO because the new
fan does not rattle around as much.
--
Poul-Henning Kamp | UNIX since Zilog Zeu
In message <4267588cdd7544d48a9a119584228...@pc52>, "Tom Van Baak" writes:
>I'm sure this requires no small effort in thermal engineering on
>their part.
The major part of this effort was to reduce the power usage to
maximize battery lifetime.
>The plot you get is then simply accuracy (or jitter
At 10:13 AM -0700 5/22/09, Tom Van Baak wrote:
One comment, and one idea on airflow...
I'm sure we could discuss for some time what airflow is too much
or too little or where to place the thermal probes or how to take IR
scans or how then interpret them. But it seems to me the bottom
line is no
Tom Van Baak wrote:
> One comment, and one idea on airflow...
>
> I've noticed that none of my high-end frequency standards use
> fans at all. That includes every Rb, Cs, and H-maser. This does
> not mean they are all cool to the touch, but my guess is it's better
> to allow temperature gradients t
One comment, and one idea on airflow...
I've noticed that none of my high-end frequency standards use
fans at all. That includes every Rb, Cs, and H-maser. This does
not mean they are all cool to the touch, but my guess is it's better
to allow temperature gradients to exist than use fans in an at
I came home one day to find *that* smell in my workshop. It turned out to be
my HP 3325B. It had been on for ages and it had also been a warm day. I
looked at the back and found the intake completely blocked up with dust.
It seems to still work, but I need to open it right up and check it out
prop
The ECL and EECL chips are located on A22 (arming board), A19 + A20
(interpolator boards), A18, A17 (count chain assembly) A8 (reference
buffer), A21 (multiplier assembly).
The interpolator boards are more or less directly in line with the
ducted airflow from the fan as are the reference buffer a
When I worked in R&D at HP's Microwave Division (1972 ~ 1976) and HP LaserJet
Division (1976 ~ 2000) we designed all our products to meet specifications
across a temperature range of -20 to +55 degrees Centigrade. I would assume
this was a standard requirement across most if not all HP products
Hal Murray wrote:
> How much ECL is used in a 5070?
A bunch
How tightly are they packed?
You need a high cooling velocity even if just one chip.
> How much of
> the heat goes directly from the chip to the air rather than from chip to
> board to air?
A substantial amount of cooling is from DIP
> This is incorrect. ECL components require a minimum airflow velocity
> that is rather high. The purpose of the large fan is to maintain this
> velocity. If a smaller fan is used, the ECL components will get
> hotter, even though the air flowing past them is not much hotter.
> When you say the
pointed out by others.
Didier
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Thursday, May 21, 2009 12:12 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 5070B once more
> -Original Message-
> From: time-nuts-boun...@febo.com
> [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard
> (Rick) Karlquist
> Sent: Thursday, May 21, 2009 9:26 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-
In message <4a15808f.4090...@karlquist.com>, "Richard (Rick) Karlquist" writes:
>"Modern" fans obey the same laws of physics as the original equipment.
>They don't magically produce more airflow for less noise.
Agreed: there is no magic to it.
But a lot has happened in aerodynamics since Hermann
Mark Sims wrote:
I have done quite a bit of work replacing fans in old equipment with modern
fans.
I have never seen a case where replacing a hurricane level fan with a
whisper
quiet fan made any real difference in the cooling inside the unit...
typically
one sees less than +/- 5C dif
When I have been concerned with 'stealing' power, I have used
a switching power supply wall wart. Small and are usually quite
efficient. One model a Sony (branded), the chip inside even had
a opto isolated control pin so it could be turned on/off via
logic.
-pete
>
>
> Yes, I have replaced the
On 5/20/09 9:18 AM, "Roy Phillips" wrote:
> Mark
> Thanks for your comments. I suspect that there was a period when the "Papst"
> fan was the de facto standard in many equipments, it has considerable depth
> and obviously moves a lot of air.
There is no real correlation between noise level an
Mark
Thanks for your comments. I suspect that there was a period when the "Papst"
fan was the de facto standard in many equipments, it has considerable depth
and obviously moves a lot of air. I can certainly see the need in the case
of Power Supplies, I have an HP6632A which can provide 100 wat
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