At 04:03 AM 7/17/04 +0200, Thomas Shaddack wrote:
On Fri, 16 Jul 2004, Major Variola (ret) wrote:
Sorry so late ---but your can-shaped capacitors might not handle the rapid depressurization so well.
Perhaps it's time to challenge the introductory assumption. Why a laptop? There are many various embedded computers available on the market, eg. the one from <http://www.gumstix.com/>.
Um, even the small form factor PC on a board the size of your palm may still rely on caps in the power supply that don't handle 760 to 0 mm Hg/min so readily. Otherwise, there are many small PCs on a card if you look into the embedded marketplace. Complete with solid state disks, etc. COTS. Power dissipation is not a problem if you use a CPU like Via's and have a nice radiative heatsink. Or dick with Peltier-effect junctions at the expense of watts. ARM's edge is low power, but you may not want to run Linux or BSD or a RTOS, perhaps anon actually wants to run M$ in a low pressure environ. Perhaps that's why he's anonymous :-) My guess is regular ole airplane takeoff, but its not quite 0 torr at 35Kfeet, and I *think* the cargo part is pressurized, lest Fido suffocate. And while a SAM would be a great science fair project, you don't go above that limit. Perhaps anon will be a space tourist, wanting to take notes, on something heavier than a PDA+keyboard. I once TA'd at a UC, one advanced ugrad had a project for an atmospheric science prof building a board for the nose of a spyplane, to sample the air. (For ozone, not nucleotides. No, really.) He was interested in vibration problems; I told him to take his proto board on an offroad trip in his car to shake out the moths. Am not sure that epoxy cover makes a difference, the board manuf. go to lengths to avoid air pockets under traces, the ICs themselves fairly (albeit not guaranteed) encapsulated in an epoxy mix. We-all being scientists, I'd suggest looking up with the vacuum hobbyists do with fridge pumps, etc, and doing a bit of testing. I've even seen using a CRT as a vacuum source, break the glass neck and shazaam, a few litres of hard vacuum. -------- Got Kalman filtering?
On Fri, 16 Jul 2004, Major Variola (ret) wrote:
Um, even the small form factor PC on a board the size of your palm may still rely on caps in the power supply that don't handle 760 to 0 mm Hg/min so readily.
However, if you use a low-power board, you have less current to filter the ripples from, so you need smaller caps, which offers you more options. You can also replace the caps in the power supply for vacuum-resistant types, for the price of some soldering.
Otherwise, there are many small PCs on a card if you look into the embedded marketplace. Complete with solid state disks, etc. COTS.
Do you know some worth of being refered to, if possible low-cost? The situation on the market is changing so fast it's difficult to keep track.
perhaps anon actually wants to run M$ in a low pressure environ. Perhaps that's why he's anonymous :-)
Maybe it's agent of Microsoft looking for expanding the market to space! (Blue sky instead of blue screen?)
My guess is regular ole airplane takeoff, but its not quite 0 torr at 35Kfeet, and I *think* the cargo part is pressurized, lest Fido suffocate.
Also, a lot of cargo can be susceptible to lower pressures. Eg, the mentioned capacitors could be popping. So some overpressure during the flight has to be maintained there.
And while a SAM would be a great science fair project, you don't go above that limit. Perhaps anon will be a space tourist, wanting to take notes, on something heavier than a PDA+keyboard.
In that case, I'd suggest to build it as a wearable computer, integrated into the space suit.
I once TA'd at a UC, one advanced ugrad had a project for an atmospheric science prof building a board for the nose of a spyplane, to sample the air. (For ozone, not nucleotides. No, really.) He was interested in vibration problems; I told him to take his proto board on an offroad trip in his car to shake out the moths.
Wise. :)
Am not sure that epoxy cover makes a difference, the board manuf. go to lengths to avoid air pockets under traces, the ICs themselves fairly (albeit not guaranteed) encapsulated in an epoxy mix.
Sealing the boards in resin, under lowered pressure, could possibly help; the pressure of the atmosphere would be replaced by the pressure of the resin. Another option could be mounting the device into a hermetically sealed case, filled with eg. silicone oil for easier heat transfer.
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Major Variola (ret) -
Thomas Shaddack