completely passive openly-designed power supply

Oli · Post by **Oli** » Sun Apr 20, 2003 4:37 am

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Post by **MikeC** » Sun Apr 20, 2003 11:39 am

relevant fanless psu mod by quix: http://forums.silentpcreview.com/viewto ... highlight= I have an article he wrote about this mod that needs final proofing; should be of interest when it is posted later in the week.

Oli · Post by **Oli** » Sun Apr 20, 2003 11:49 am

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Bat · Post by **Bat** » Mon Apr 21, 2003 10:49 am

Don't neglect the possibility of watercooling as an alternative to having lots of big fins that stick out at the back and need good ventilation.

It shouldn't be too hard to design it so that the water system has no joints inside the PSU casing, so there should be no leaks.

It's essential to ensure the heatsinks are well earthed (not live) whether they're external or water cooled, so there's no difference in that respect.

Post by **Rusty075** » Mon Apr 21, 2003 11:35 am

Rather than completely redesigning the PCB to move the mosfets, why not just attach extention wires to them and attach them to an external heatsink.

A bit like BladeRunner did here: Zero Fan Zone although he was doing it to attach a waterblock it could just as easily be attached to a big heatsink haning out the back of the case.

wussboy · Post by **wussboy** » Mon Apr 21, 2003 12:22 pm

Water and power supplies are like Tequila and hand guns. They're dangerous to mix. But oh what fun if you do!

energy · Post by **energy** » Mon Apr 21, 2003 7:07 pm

Now if we can only come up with an easy solution to passively cooling down a high end P4...I recall some Japanese site when some guy used multiple Zalmans and later a huge black aluminum anodized heatsink ripped off of a stereo amp to cool it down, it ended up covering all the space between the AGP port all the way up to the power supply

I saw a Thunderbird 1.4 running passive... the guy didn't use a case, just laid the mobo down on one of those carts (with the shelf on the bottom for hard drive, PSU etc), Alpha 8045 on graphics card, a big hunk of metal on the CPU, with a combination of huge heatsinks epoxied onto it... don't remember quite where I saw it...

powergyoza · Post by **powergyoza** » Mon Apr 21, 2003 8:27 pm

I believe that was SPCR's bluehat that did the passive thunderbird. http://members.fortunecity.com/bluehat1/index.html

Oli · Post by **Oli** » Tue Apr 22, 2003 2:19 pm

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Oli · Post by **Oli** » Wed Apr 23, 2003 5:09 am

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larrymoencurly · Post by **larrymoencurly** » Wed Apr 23, 2003 10:58 pm

How about finding some 90% efficient 12V PSUs on the surplus electronics market and talking/tricking Texas Instruments into giving you some of their 90% efficient modules that take 12V and convert it down to anywhere from 2V-7V (no pots -- jumpers)? Those modules are rated for up to about 32A output and are about 4" x 2" x .5"

Oli · Post by **Oli** » Thu Apr 24, 2003 2:13 am

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Oli · Post by **Oli** » Thu Apr 24, 2003 2:20 am

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Bat · Post by **Bat** » Sun Apr 27, 2003 5:35 pm

Come to think of it, I'll go a stage further in recommending that you consider designing with water cooling in mind.

I think the main application for a silent PSU would be in a silent PC. In a merely very quiet PC, something like a Silenx PSU would be adequate. To get the rest of the PC silent if there's no air being drawn through the PSU, a water-cooling system is pretty much the only way to go. Therefore, if the situation warrants this silent PSU you're designing, you can be pretty sure there will be a water system present. It wouldn't be much effort to plumb in one extra component.

Oli · Post by **Oli** » Mon Apr 28, 2003 4:46 am

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jamoore9 · Post by **jamoore9** » Mon Apr 28, 2003 6:44 am

This certainly sounds ambitious.

But Oli, if the only fan in your system is in the PSU, and I would assume that it is therefore the primary exhaust for the system, and you are intent on removing it, then you are left with a quandry. Will you not exhaust the system, or will you add an exhaust fan elsewhere? I'm just curious. Seems to me that adding a fan to the case sort of negates the need to remove the fan from the PSU. Unless I'm missing something... which I might...

Oli · Post by **Oli** » Mon Apr 28, 2003 7:49 am

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Post by **Rusty075** » Mon Apr 28, 2003 12:26 pm

I don't know if I'd hold the Cube up as an example of good thermodynamic design.

Just a do web search and you'll find lots of complaints about how many of them overheated and died. Apple added fans to all the later versions of the Cube.

If anything, its a better example of a comapny letting marketing and packaging taking precident over R&D work.

Post by **MikeC** » Mon Apr 28, 2003 12:41 pm

It may not have been the best execution, and perhaps there should have been guidelines about acceptable ambient temps for safe operation and an active cooling option, but the basic fireplace/chimney cooling concept of the cube remains unbelivably cool -- well that might be a bad word choice

One of my projects in the frankensteinish lab downstairs is a fanless system that combines 3 chimneys for cooling -- one for the CPU, another for the PSU, and the last for the suspended drives. ALL aluminum case, looks ugly as sin but if it works out, could be a totally silent system. Main question right now is whether I need to modify the CPU smokestack to include VGA cooling.

AndrewC · Post by **AndrewC** » Mon Apr 28, 2003 1:47 pm

Could you please show pics

Post by **MikeC** » Mon Apr 28, 2003 2:32 pm

AndrewC wrote:Could you please show pics

It's not ready even for a backroom show & tell, just a mess of stuff right now. I haven't had any time to work on it. Will become an article when it is working decently and looks halfway presentable.

Mr_Smartepants · Post by **Mr_Smartepants** » Tue Apr 29, 2003 11:48 pm

Rusty075 wrote:I don't know if I'd hold the Cube up as an example of good thermodynamic design.

I don't know, I thought it was a pretty slick design! I used to own one.

The only audible component was the hard drive.

Rusty075 wrote:Just a do web search and you'll find lots of complaints about how many of them overheated and died. Apple added fans to all the later versions of the Cube.

That's absolutely NOT true!

Apple designed a fan mount to the base of the chassis because they were planning dual-processor cubes down the road (Which Apple never built but the aftermarket did). They NEVER shipped a single cube with a fan added. Any cube you find with a fan, guaranteed the end-user added that fan (I did, panaflo 80x15mm). The only reason I added a fan was because I replaced the video card with a GeForce 3.

Rusty075 wrote:If anything, its a better example of a comapny letting marketing and packaging taking precident over R&D work.

Yeah I'd have to agree with you there. Apple's marketing sucks. The reason Apple machines are so expensive is that they have to recoup the costs of massive R&D. That's why I left the Apple circle and 'switched' to PC.

Post by **MikeC** » Wed Apr 30, 2003 12:00 am

It's not ready even for a backroom show & tell, just a mess of stuff right now. I haven't had any time to work on it. Will become an article when it is working decently and looks halfway presentable.

One thing I will say is this: with fanless systems, high power dissipation components aren't practical for many reasons:

- big challenge
- high cost
- typically, considerally higher weight (mostly for HS)
- reliability issues
- safety / heat

This last factor has rarely been talked about but I find it is real. When you have fans blowing, the 150W that's in your system is being moved fairly quickly, it doesn't just stick around in one place. Even with real low airflow fans.

When you reply on only natural convection, the heat "pools" more, and external components such as HS exposed to the outside of the case get very hot. Hot enough that it could get dangerous, even though the component temp (as in a CPU) might be perfectly safe (like at 60C). If the HS is at >50C and it is exposed on the outside of the case, believe me, it can be a safety issue.

High efficiency in the PSU and low power dissipation in the components get totally important. I'm actually waiting to see if I can get hold of a higher efficiency PSU to continue this project. I doubt I'll go for much more power than an XP1700, and undervolt it, too.