Mini 12 volt ATX PSUs

[Tim B]

Good Evening Ladies and Gents,

I have recently bought two 12 volt ATX power supplies. These are now employed powering my 2 rackmount home PCs. These PCs are both 2.4GHz P4s. So far (as I am typing this) the PSU is working like a dream.

Now, for those of you who thinks that a man with a pair of custom 12Volt rackmount PCs on his desk can't possibly be trusted, I'm intending to add another two 12 Volt rackmount watercooled PCs over the next year, with a 12Volt 3U Server early in 2009. There is a point to this, though, in that the design of the new rackmount boxes is very close to the design of a completly sealed marine computer system.

Hopefully the power supplies and water-cooling will prove itself over the next 12 months, and the technology will be ready to be transferred to a yacht.

The product link is: http://www.itx-warehouse.co.uk/Produ...?ProductID=253

Cheers,

Tim B.

[TerryKing]

Originally Posted by Tim B

..snip.. There is a point to this, though, in that the design of the new rackmount boxes is very close to the design of a completly sealed marine computer system.

Take a look at: http://www.boatdesign.net/wiki/Onboa...oard_Computers
on our Wiki. Several of us here are interested in working on these areas.

I have a mini-iTX system board that runs with no fan.. which I intend to run in a waterproof enclosure of some kind.. My test equipment and tools are supposed to arrive Real Soon Now, and I can get back to work (Just moved to China..).

Are the power supplies you have rated for use in a vehicle 12V system? The issues of transient protection etc. are something I need to understand better.

I'd like to start a thread on 12V powered low-power general-purpose computers for shipboard use..

Let's figure some stuff out!

[Tim B]

The ones I'm using don't have automotive protection, but some others in the range do. I think it's a reasonable assumption to expect them to work ok.

The advantage of an ATX-based system is processing power. It's a trade-off between processing and electrical input power.

for more info see http://www.mini-box.com/s.nl/sc.8/category.13/.f

Cheers,

Tim B.

[Tim B]

Rackmount PC layout for anyone who's interested

[BillyDoc]

Tim and Terry,

I've been thinking about this as well, and one idea I have had is to simply flood a watertight box containing the computer mother board with silicone or mineral oil, and then re-circulate the oil to a hull mounted (or integral part of the hull) heat exchanger. I would put old-fashioned heat sinks on the high heat items like the CPUs, and make sure there was plenty of oil circulation over them. I'm talking about an aluminum hull, which of course makes this much easier. All that water on the other side of the hull should make a great heat-sink.

This isn't going to work with a DVD reader, but some company (Seagate?) recently announced that they will be bringing out a line of solid-state drives next year, and those could probably go in the oil as well. Perhaps the power supply could too after removing any fans.

It would sure be messy to work on, but I rarely have to actually open up my box for anything.

My main concerns are . . . what is that oil going to dissolve and can I get enough thermal transfer into the oil?

Any thoughts?

BillyDoc

[TerryKing]

BillyDoc, we should look more at what the Extreme Gaming guys are doing. I know some of them run processor heatsinks that are water cooled. I THINK I saw something about a system running in Freon etc.

I hope we don't need anything like that kind of compute power for typical onboard computers running NAV plus Monitoring and control, and Entertainment / DVD Movies at anchor. The newer VIA fanless systems can do all that I think.

I would like to look at using one of the 'Heat Pipe' coolers to move heat from 'inside the sealed box' to the outside if needed.. I'd LIKE to use an ABS plastic box with sealing cover so I can get at things easily. One of my kids designs stuff that goes on mountain-tops all over the world, in boxes like that. Look at:
http://www.nrgsystems.com/store/prod...p?cd=10&s=3147
to see the box. (Photo below, too)..
These boxes are rated like this:
- Weatherproof polycarbonate, meets the following specifications:NEMA type 4, 4X and 13, IEC: IP65

I need to look at the details of these specs, but I understand that these units pass the 'pail of salt water' test...

I have a VIA EN12000EG Mini-ITX System board that I hope to fire up next week...

Tim B, maybe we're ready to start a more general thread about onboard computers, and continue the power supply discussion you started there. What do you think??

[Tim B]

I had an interesting situation yesterday, when trying to get an adequate power distro setup. It seems that 3.5" hard drives are very sensitive to the voltage on the +12V rail. I found that the voltage drop along the supply lead was too great for the drives to spin-up. The solution to this is to use a 2.5" HDD which runs on +5V.

For casing I am a great advocate (particularly with water-cooling) of sealing the case permanently. That way, the motherboard is in a well-controlled environment. In the case of an on-board system I doubt you'd need to open the case any-way.

The DVD drive on the above PDF doesn't need to be there particularly for marine operations. A sealed SATA connection would be preferable with the DVD drive in a more accessible location.

There are a number of solid-state hard-drives available upto 64GB. That's more than enough for a Linux install + data. More storage can always be added via SATA/USB.

Tim B.

[TerryKing]

Originally Posted by Tim B

I had an interesting situation yesterday, when trying to get an adequate power distro setup. It seems that 3.5" hard drives are very sensitive to the voltage on the +12V rail. I found that the voltage drop along the supply lead was too great for the drives to spin-up. The solution to this is to use a 2.5" HDD which runs on +5V...snip..
The DVD drive on the above PDF doesn't need to be there particularly for marine operations. A sealed SATA connection would be preferable with the DVD drive in a more accessible location.

Tim, was the 12V being supplied from the ATX power supply? Maybe it's current capability was not enough.. I've wondered about operating stuff like that (and LCD display etc) directly from the +12V supply.

DVD: Totally agree.. this should be totally separate from the system case. SATA is an easier-smaller cable to waterproof, although I have seen ribbon cables like an ATA100 going thru RTV Silicone and I expect that would be fine... The DVD drive could be in a very protected area below decks, and even then is a separate simple NEMA4 box with a snap-lock cover. You only need to open it to put media in..

I'm about to work more on a list of what a "Multipurpose Onboard Computer" would have for capabilities. I'd like to start a broad discussion on that soon...
It's raining like heck in Shekou/Hong Kong for the first time in 2 weeks so I have a good reason to stay inside

[Tim B]

Yes, the supply (from on ATX PSU) goes to a distro box, then to the computer. although it would appear that my idea of 12 volts and that of the PSU developers differ slightly. I was expecting some voltage drop, and it is unlikely that it would be an issue for on-board use (as we're starting well above 12 volts).

Tim B.

[TerryKing]

Discussion- Multi-purpose Onboard Computers
now has a thread for a general discussion on onboard computers, powering them etc.

My prejudice is against water-cooling - yet something else to go wrong on the boat.
Suggestion: mount the motherboard etc in an ally box with fins on both the inside and outside. That will take care of passive (convection) cooling for everthing except the CPU.

I still use Socket 7 motherboards on the boat which I underclock to get the heat down. The remainder of the heat is conducted to the case via a conduction cooler: simply a brass plate epoxied to the CPU to which has been soldered a heavy-duty copper braid (ex automotive grounding strap). A brass plate soldered to the other end is bolted to the case. Keep life simple.
Colin

[TerryKing]

Originally Posted by SAE140

(..snip..)The remainder of the heat is conducted to the case via a conduction cooler: simply a brass plate epoxied to the CPU to which has been soldered a heavy-duty copper braid (ex automotive grounding strap). A brass plate soldered to the other end is bolted to the case. Keep life simple.Colin

Colin, please check in as we work on this heat/transfer issue over in the other thread mentioned below. There is a similar idea in which a 'heat pipe' goes from Processor thru a cabinet wall to outside. A passive vapor-liquid heat pipe can move much more heat energy than an equivalent copper or silver bar.

I agree with the Keep It Simple.. no powered parts approach!

((Added a photo below.. This is for getting 100 watts out of a 3 Ghz multi-processor. Something like this should work passively for 15 or 20 watts inside a sealed box ))

See: http://en.wikipedia.org/wiki/Heat_pipe

Hi Terry
thanks for the reply.

I went over to the Wiki thingy - and blow me down - I've got a CPU cooler on the shelf which looks exactly like the one in the top photo.
Two copper pipes with carefuly sealed ends. I thought it was just some kind of wacky construction technique !
'Master Cooler' is the brand name. Up for grabs if anybody want to play with it.
Cheers
Colin

Almost forgot ...

If you guys are focussing on engine management/ battery state and tankage indicators and so forth, then checkout: http://www.vermontficks.org

There's a Seatalk interface and GPS repeater and much more there.
http://www.vermontficks.org/gpsd.htm is a good place to start.

The guy uses PICs: nano-watt technology - no need for cooling <G>.

[TerryKing]

Originally Posted by SAE140

If you guys are focusing on engine management/ battery state and tankage indicators and so forth, then checkout: http://www.vermontficks.org

VERY Small World! Jon Fick is an old friend of mine from IBM (I'm from Vermont, living in China the next 2 or 3 years).. I'll talk with him about this stuff!

I have developed things with PIC microcomputers and I'm working on an NMEA0183 Engine Monitor with NMEA Multiplexor for several channels.

Small World! Thanks...

[donncha]

In response to the comment about oil cooling:

You wouldn't need any heat sinks at all as there is enough heat transfer from the oil directly to the mother board and cpu. The only thing you have to worry about is any moving parts.

Oil has been used several times else where. I saw a guy once who simply dumped all his components barring the hdd and the cd drive into a fish tank filled with oil and ran the computer form there.

I myself was considering using an ammunition box filled with motor oil(as it's non conductive and has good thermal properties) to run a fully contained/waterproff pc for on-board usage. Or you could simply just use ordinary passive cooling (i think oil is more fun).

Look at http://www.mini-itx.com/projects/ammobox/