K
Klaus Vestergaard Kragelund
Guest
On 19-08-2022 21:02, John Larkin wrote:
Many of the Chinese ones has horrible CM noise
Many of the Chinese ones has horrible CM noise
C
Clive Arthur
Guest
On 20/08/2022 00:57, Klaus Vestergaard Kragelund wrote:
<snip>
There was a DIL chip for use as an inclinometer which had a miniature
heater and two thermistors plus signal processing, and used the
differential temperature due to air convection to provide tilt. It was
a long time ago, before MEMS.
--
Cheers
Clive
<snip>
There was a DIL chip for use as an inclinometer which had a miniature
heater and two thermistors plus signal processing, and used the
differential temperature due to air convection to provide tilt. It was
a long time ago, before MEMS.
--
Cheers
Clive
S
server
Guest
On Sat, 20 Aug 2022 12:34:59 +0100, Clive Arthur
<clive@nowaytoday.co.uk> wrote:
There were also electrolytic (liquid) inclinometers.
I designed a level sensor system for the C5A Boresight Alignment Kit.
It used a Talyvel inclinometer, basically a pendulum and LVDT.
<clive@nowaytoday.co.uk> wrote:
There were also electrolytic (liquid) inclinometers.
I designed a level sensor system for the C5A Boresight Alignment Kit.
It used a Talyvel inclinometer, basically a pendulum and LVDT.
C
Clive Arthur
Guest
On 20/08/2022 16:12, jlarkin@highlandsniptechnology.com wrote:
Electrolevels could be very accurate and reliable. Long ago, I
installed many to monitor slope stability on an embankment and movement
on a flyover in Wales, all cabled back to a hut which would get visited
less and less frequently. I expect they\'re still there after forty
years or more.
They obviously work, because the embankment hasn\'t slipped yet
--
Cheers
Clive
Electrolevels could be very accurate and reliable. Long ago, I
installed many to monitor slope stability on an embankment and movement
on a flyover in Wales, all cabled back to a hut which would get visited
less and less frequently. I expect they\'re still there after forty
years or more.
They obviously work, because the embankment hasn\'t slipped yet
--
Cheers
Clive
C
Cydrome Leader
Guest
jlarkin@highlandsniptechnology.com wrote:
Omega is garbage these days. They struggled and failed to find a
replacement for one of discontinued temp controllers. They clearly had no
idea what they used to make, or what they make now.
Went with Novus. Weird pre-sales support (they\'re in brazil), but it was
legit and they have real distributors in the US. Will bump to the top of
the list for anthing temp control. The omron stuff is just overly complex.
Do you care about temperatures or the airflow numbers? It\'s sort of
shocking that the cooling is poor/uneven in that chassis illustration.
Omega is garbage these days. They struggled and failed to find a
replacement for one of discontinued temp controllers. They clearly had no
idea what they used to make, or what they make now.
Went with Novus. Weird pre-sales support (they\'re in brazil), but it was
legit and they have real distributors in the US. Will bump to the top of
the list for anthing temp control. The omron stuff is just overly complex.
Do you care about temperatures or the airflow numbers? It\'s sort of
shocking that the cooling is poor/uneven in that chassis illustration.
S
server
Guest
On Sun, 21 Aug 2022 00:30:22 -0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:
We want air flow over the eight boards to cool parts. Some will have
local heat sinks here and there. I was hoping for 200 LFPM on the
worst board with the fans running at some tolerable noise level.
Any board that thinks it\'s getting too hot can request that the fan
speeds be increased.
As noted, the two fans are fire hoses of air. Slot 3, about in the
center, gets about a tenth the flow of slot 1, which gets a full fan
blast.
Blowing air out the front panel (it currently intakes) has upsides,
probably better distribution between boards. But it has downsides too.
<presence@MUNGEpanix.com> wrote:
We want air flow over the eight boards to cool parts. Some will have
local heat sinks here and there. I was hoping for 200 LFPM on the
worst board with the fans running at some tolerable noise level.
Any board that thinks it\'s getting too hot can request that the fan
speeds be increased.
As noted, the two fans are fire hoses of air. Slot 3, about in the
center, gets about a tenth the flow of slot 1, which gets a full fan
blast.
Blowing air out the front panel (it currently intakes) has upsides,
probably better distribution between boards. But it has downsides too.
S
server
Guest
On Sat, 20 Aug 2022 01:59:04 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:
300 watts, $72, free shipping, and amazing voltage accuracy and
stability.
<klauskvik@hotmail.com> wrote:
300 watts, $72, free shipping, and amazing voltage accuracy and
stability.
K
Klaus Vestergaard Kragelund
Guest
On 20-08-2022 18:00, Clive Arthur wrote:
There is of course many solutions. The point of the one we did was that
this was for high volume, cost sensitive, so only a 1cent solution would
be allowed
On 20/08/2022 16:12, jlarkin@highlandsniptechnology.com wrote:
On Sat, 20 Aug 2022 12:34:59 +0100, Clive Arthur
clive@nowaytoday.co.uk> wrote:
On 20/08/2022 00:57, Klaus Vestergaard Kragelund wrote:
snip
I did an experiment once where we had a problem with the orientation of
a product. So burned power into a resistor on the PCB, surrounded by 4
NTC resistors. We did in fact detect orientation. in 2 planes. But
then,
what about the third plane?
There was a DIL chip for use as an inclinometer which had a miniature
heater and two thermistors plus signal processing, and used the
differential temperature due to air convection to provide tilt. It was
a long time ago, before MEMS.
There were also electrolytic (liquid) inclinometers.
I designed a level sensor system for the C5A Boresight Alignment Kit.
It used a Talyvel inclinometer, basically a pendulum and LVDT.
Electrolevels could be very accurate and reliable. Long ago, I
installed many to monitor slope stability on an embankment and movement
on a flyover in Wales, all cabled back to a hut which would get visited
less and less frequently. I expect they\'re still there after forty
years or more.
They obviously work, because the embankment hasn\'t slipped yet
There is of course many solutions. The point of the one we did was that
this was for high volume, cost sensitive, so only a 1cent solution would
be allowed
C
Cydrome Leader
Guest
jlarkin@highlandsniptechnology.com wrote:
just as a tip, nobody cares about the airflow numbers. It\'s all about
temperatures. Over 100 temp readings are possible in modern servers. None
of the instrumention is about airflow itself, because it just doesn\'t
matter once the minimums are met. For example, different sizes and shapes
of heatsinks in the same flow of air behave differently.
You may need to watch out if their air speeds are high and you want to
control air flow with a piece of swiss cheese. Noise and turbulence will
be your new friends.
If you want to go real extreme, use a blower and actual tubes/pipes to
distribute the air where you need it. Think irrigation system, or old
avionics.
just as a tip, nobody cares about the airflow numbers. It\'s all about
temperatures. Over 100 temp readings are possible in modern servers. None
of the instrumention is about airflow itself, because it just doesn\'t
matter once the minimums are met. For example, different sizes and shapes
of heatsinks in the same flow of air behave differently.
You may need to watch out if their air speeds are high and you want to
control air flow with a piece of swiss cheese. Noise and turbulence will
be your new friends.
If you want to go real extreme, use a blower and actual tubes/pipes to
distribute the air where you need it. Think irrigation system, or old
avionics.
J
John Larkin
Guest
On Mon, 22 Aug 2022 18:34:33 -0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:
Too late now. But getting fairly uniform air flow into 8 tubes could
get interesting too.
The baffle is a first approximation to a positive-pressure plenum with
controlled-resistance exits.
<presence@MUNGEpanix.com> wrote:
Too late now. But getting fairly uniform air flow into 8 tubes could
get interesting too.
The baffle is a first approximation to a positive-pressure plenum with
controlled-resistance exits.
C
Clive Arthur
Guest
On 21/08/2022 22:17, Klaus Vestergaard Kragelund wrote:
<snipped>
Yes. For the required accuracy, it was a clever design. Ingenious.
--
Cheers
Clive
<snipped>
Yes. For the required accuracy, it was a clever design. Ingenious.
--
Cheers
Clive
L
legg
Guest
On Thu, 18 Aug 2022 19:34:32 -0700, jlarkin@highlandsniptechnology.com
wrote:
the rear, it can equalise flow through equalised back-pressure.
Looks like the boards are too close to the rear wall, but that can be
used to increase influence of the exhaust pattern.
Use of back pressure eventually means less net airflow.
RL
wrote:
Hard to predict without an exhaust vent profile. if centered in
the rear, it can equalise flow through equalised back-pressure.
Looks like the boards are too close to the rear wall, but that can be
used to increase influence of the exhaust pattern.
Use of back pressure eventually means less net airflow.
RL
S
server
Guest
On Tue, 23 Aug 2022 08:18:22 -0400, legg <legg@nospam.magma.ca> wrote:
The back panels will have various cutout sizes that depend on how much
air flow each type of module needs. That of course complicates things
more.
Would a rear plenum help? Our current rear plenum is the world.
Sure. We want some guaranteed minimum flow in the worst slot, 200
f/min as a target.
The back panels will have various cutout sizes that depend on how much
air flow each type of module needs. That of course complicates things
more.
Would a rear plenum help? Our current rear plenum is the world.
Sure. We want some guaranteed minimum flow in the worst slot, 200
f/min as a target.
L
legg
Guest
On Tue, 23 Aug 2022 07:08:34 -0700, jlarkin@highlandsniptechnology.com
wrote:
An interesting number. You mean linear FPM ?
With local scrubbers (which is what you\'ve been touting in the past),
your only interest would be delta T of the air, by the time it
leaves the box. No numbers on the drawing, but assuming an 18\" rack
mount, that would mean >> 100 cubic feet / minute of air volume
delivered by the fans.
Check the fan spec sheets. What\'s the air volume capacity of the
fans at full speed?
100ft^3 is about 3m^3
standard air density 1.276 kg/m3
specific heat capacity of air is 1.006 kJ/kgK
So you\'re heating about 4Kg ( 3 x 1.276) of air every 60 seconds
- that\'s .067kg per second - .067kj or 67W for every degree C rise.
If the air volume halves, delta T doubles.
If energy absorption doubles, delta T doubles.
With an energy load of x watts, that gives you box air volume
requirements in your environment.
Air volume (feet per minute - linear or cubic) will depend on
back-pressure presented to the fans. I expect it will be
considerably less than 100 cubic feet / minute.
RL
wrote:
An interesting number. You mean linear FPM ?
With local scrubbers (which is what you\'ve been touting in the past),
your only interest would be delta T of the air, by the time it
leaves the box. No numbers on the drawing, but assuming an 18\" rack
mount, that would mean >> 100 cubic feet / minute of air volume
delivered by the fans.
Check the fan spec sheets. What\'s the air volume capacity of the
fans at full speed?
100ft^3 is about 3m^3
standard air density 1.276 kg/m3
specific heat capacity of air is 1.006 kJ/kgK
So you\'re heating about 4Kg ( 3 x 1.276) of air every 60 seconds
- that\'s .067kg per second - .067kj or 67W for every degree C rise.
If the air volume halves, delta T doubles.
If energy absorption doubles, delta T doubles.
With an energy load of x watts, that gives you box air volume
requirements in your environment.
Air volume (feet per minute - linear or cubic) will depend on
back-pressure presented to the fans. I expect it will be
considerably less than 100 cubic feet / minute.
RL