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 Post subject: External Power Supply
PostPosted: Tue Nov 11, 2003 12:19 pm 
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Joined: Mon Oct 06, 2003 8:28 pm
Posts: 40
I've been rumaging through my brain for some ideas to design a descent semi-quiet solution for 3 PC's and a central file server in a converted bedroom -> office. My goal is to have the room fairly silent. My second goal is to be able to have one huge central file storage machine in the closet, which wouldn't need very much processing power. After that each machine would run off of a 20-40GB 2.5" 4200RPM drive. Given what I do with my computers I'm not as concerned about speed as I am silence.

Now on to the question now that the unneeded babbling is out of the way. Is it possible to have an external power supply, and run the PC from a location 10-15 away from the PSU. I would really like to have my 3 machines PSU's in the closet and worry about cooling the PC's passivly with heatpipe, similar to the recent SPCR article.

Thanks,
Traciatim


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 Post subject:
PostPosted: Tue Nov 11, 2003 5:32 pm 
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Joined: Sun Aug 11, 2002 3:26 pm
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Location: Philadelphia, PA, USA
Adding 10-15ft of distance to the PSU power leads will not work. The wire itself would eat up too much current (due to the resistance of the wire). It would be near impossible for the PSU to keep the voltages in spec.

Since you'll have to put the PSU with the computer, you'll want to make it as quiet as possible. If you're serious about fabbing heatpipes to cool your CPUs, then modding your PSU to use giant heatsinks (like this) shouldn't scare you. Of course, you could also just drop big bucks on the ProSilence passive PSU (although some users are less than happy with it).

But, if all you want is something "fairly silent", you may be able to get away with some of the standard recommended components at SPCR. Putting these kind of PCs in one corner of the room and using an extened KVM extension (and maybe a USB extension/repeater/hub for an external CD) would probably get you the silence you want, with much less fuss.


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 Post subject:
PostPosted: Tue Nov 11, 2003 8:50 pm 
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Justin_R wrote:
Adding 10-15ft of distance to the PSU power leads will not work. The wire itself would eat up too much current (due to the resistance of the wire). It would be near impossible for the PSU to keep the voltages in spec.


It's not the resistance of the leads you need to worry about. It's the leads picking up various kinds of interference that will give you problems. Long leads like that act just like antennea and they will fill your nice clean power full of of spikes and noise. So if you can find a suitable solution to that problem, then there is no reason you couldn't have an external PSU like this guy wants. Of course you basically would need to be an EE to figure this problem out, so you are totally right in suggesting a less-extreme solution.

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 Post subject: External Heat Sink / Passive Heat Sink
PostPosted: Thu Nov 13, 2003 7:10 am 
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Actually, I think your both right. After looking into it, it does seem that running 12/5VDC with high current down a 10-12AWG wire does impose around a 10-15% loss in voltage, which probably would cause some major problems in a PC.

Also, the non-clean signal would wreak havoc on the machine, but that could probably be cleaned up with smal capacitors on each device connected.

I guess the best route would be then to look in to lower power devices, and low wattage passive power supply.

Thanks for the response,
Traciatim


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 Post subject: Re: External Power Supply
PostPosted: Wed Nov 19, 2003 11:42 pm 
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Joined: Thu Feb 06, 2003 5:27 am
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Traciatim wrote:
Now on to the question now that the unneeded babbling is out of the way. Is it possible to have an external power supply, and run the PC from a location 10-15 away from the PSU. I would really like to have my 3 machines PSU's in the closet and worry about cooling the PC's passivly with heatpipe, similar to the recent SPCR article.

Thanks,
Traciatim


There are several products already available in Japan. One is to convert existing ATX power supply external.

http://www.soho-jp.com/goods/pcparts/sotodenkit.htm
The cable length is about 3ft (1m).

http://www3.soldam.co.jp/psu/vex350/index.html
This PSU has 5ft (1.5m) of cable.

Unfortunately, these are only available in Japan.

For very small machine (like mini ITX), you can buy
http://www.lex.com.tw/Images/20030401/Large/PW004-b.jpg
or something similar to this, which I actually use for a SFF.


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 Post subject:
PostPosted: Thu Nov 20, 2003 9:52 am 
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Joined: Wed Jun 04, 2003 11:20 am
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Location: california
Actually, I think both of the earlier posters are wrong.

You will not have excessive voltage drop as long as you run appropriate size cable. The national electric code permits #10 wire for 30 amps which should be more than adequate. #10 rolmex (yeah, rolmex is a brand name, but it is used as generically as people saying coke when they mean any soda) is quite cheap at your local home store. You should have less than a 1% voltage drop running 30 amps through #10 wire for 15 feet. You can probably get away with the dirt cheap, common #12 for a reaonably lightly loaded system, but frankly, the price difference is so little, you might as well run #10 for +5, +12 and +3.3. Run a length of length of 14-3 to pick up the other -5, -5sb and power on. Remember that the bare copper wire is chassis ground, not signal ground when figuring out where to connect it. Earth loops are nasty things to trace ..

As for noise.. Frankly, it probably won't be a problem. There is not much inductance on the line and your system has a fairly high capacitive load. If you were concerned, you might put a big and a little cap (1000 uf and .1) across each rail when you adapt from the rolmex back to pigleads going into your case.

Not sure how you were planning on doing this. One way that does not involve modifying your power supply would be to build a pair of "plug boards" that have all the plug you plan on using. Plug a standard power supply into one end and make up some leads to go on the other. A cheaper way would be to open a supply, unsolder the leads, solder on your rolmex and patch the leads you removed on to the end of the rolmex. You will have to spend a little time thinking this one through since rolmex is not flexible. I would probably go with some sort of connector panel/module at the ends of the rolmex and run patch cables into the supply/system unit.

Lastly, there may be some value in using remote sense power supplies in stead of consumer grade atx type supplies. A remote sense supply lets you adjust the voltage at the load as opposed to setting the voltage at the edge of the supply. 30 amp remote sense supplies are not cheap, not even on ebay, so this is not an option for the budget minded.

Anyway, remote mounting your power supply is not a big deal. You will be able to move about 20% of the heat output some distance away from the system unit (the 20% you are removing is the inefficiency in the power supply). Then all you have to do is deal with the other 80% of the heat..

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 Post subject: Re: External Power Supply
PostPosted: Sun Jan 06, 2013 4:40 pm 
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Joined: Sun Jan 06, 2013 4:39 pm
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What happened to the pictures on this thread?


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 Post subject: Re: External Power Supply
PostPosted: Mon Jan 07, 2013 7:10 am 
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Joined: Sat Nov 23, 2002 6:33 am
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gdr wrote:
What happened to the pictures on this thread?


My guess is that it has something to do with the fact that this is a 9+ year old thread. Most likely the pic hosting service that was used 9+ years ago is history.

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