Is Utah located near Antarctica?
On 5/19/2015 9:59 AM, Chuck McCown wrote:
We hit –69 here in Utah. (and +116 too, 185 degree spread)
http://www.deseretnews.com/article/116318/PETER-SINKS-UTAHS-COLDEST-SPOT.html?pg=all
*From:* Bill Prince <mailto:[email protected]>
*Sent:* Tuesday, May 19, 2015 7:55 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] Enclosure low temperature
-40 is almost 100 degrees lower than we ever see inside any of our
cabinets. Just checking around our network, about the lowest I see
anytime in the last year has been ~~ 50 degrees.
bp
<part15sbs{at}gmail{dot}com>
On 5/19/2015 6:50 AM, Chuck McCown wrote:
I would think the worst case scenario is being cold soaked.
Power is off for a week. Power comes back on. -40 outside, the chip
will be –40.
Pour some liquid butane on it to warm it up...
*From:* Bill Prince <mailto:[email protected]>
*Sent:* Tuesday, May 19, 2015 7:47 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] Enclosure low temperature
How about actual data? For the last week, the ambient outdoor temp at
this site has been between 50 (night time), and 60 (daytime). The
SiteMonitor temp inside this 18x16x10 enclosure has been like below.
So for at least this situation, it's been running between 10 and 20
degrees above ambient. The daytime temp is probably higher because of
sun exposure.
bp
<part15sbs{at}gmail{dot}com>
On 5/19/2015 6:34 AM, Chuck McCown wrote:
Back to the original question, need more data. It is a question of
physics. Jaime touched on it.
Live load.
Ambient temp.
Thermal conductivity of the enclosure.
Surface area of the enclosure.
Wind speed at coldest temp.
Thermal convection currents inside the enclosure.
Thermal conduction currents inside the enclosure.
Not trivial.
Perhaps use some transistor grease and place a rectangular type
metal plate resistor on the memory. Add a tiny bit of foil and
insulation. It would take so little energy to get the memory up
into the safe region that it could probably happen in a few
seconds. As has been mentioned, the pre-heat on boot would
certainly do that. Once booted, measure the temperature and heat or
not heat. Be a fun experiment. The memory thermal mass is so small
the resistor probably would have more thermal mass. You could get a
50 degree rise in maybe 5 seconds with 1/4 watt if insulated properly.
*From:* Forrest Christian (List Account) <mailto:[email protected]>
*Sent:* Monday, May 18, 2015 8:09 PM
*To:* af <mailto:[email protected]>
*Subject:* [AFMUG] Enclosure low temperature
What is the lowest temperature that each of you would normally
expect to see in your enclosures?
The reason I'm asking is that I'm in the process of developing up a
few new products.
To date, all of the packetflux products are designed with components
rated -40 to +85C (I.E way cold to way hot). I'd like to retain
this rating, but I'm running into a minor snag:
For storage, I'm planning on integrating a SD card (probably
microSD) in a socket. I only need a GB or so, and SD card memory
is inexpensive at that range.
Unfortunately, all the reasonably priced SD cards are only rated
down to about -25C or -13F. which are about ~$3 in qty.
"Industrial temperature range" ones which are good down to -40C/F
are available but they add at least $30 to the cost for non-name
brand, and even more for known brands. When you're talking about a
$100 end-user price, a $30 1GB SD card seems excessive - and
probably isn't even possible if I want to meet the $100 price with
some margin.
So, I'm currently playing the 'what options do I have' game. I
hate to ship a product only rated down to -25C/-13F, but I know for
at least a large chunk of my customer base they never see below this
temperature, especially when you add a watt of power dissipation in
the case with the device. Which leads me back to my original
question: What's the lowest temperature most people would expect to
see inside their enclosures.
--
*Forrest Christian* /CEO//, PacketFlux Technologies, Inc./
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
[email protected] <mailto:[email protected]> |
http://www.packetflux.com <http://www.packetflux.com/>
<http://www.linkedin.com/in/fwchristian>
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