200W passive power source

PSUs: The source of DC power for all components in the PC & often a big noise source.

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gksam
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200W passive power source

Post by gksam » Fri Aug 27, 2004 9:49 am

Similar to what is used in the shuttle.

http://www.mini-box.com/pw-120-M.htm

They claim it can power "most" motherboards, with up to 3.0 ghz.

Wonder if anybody tried such a thing for a moderate-PC (i.e. P4 2.4 with modest video card, single harddrive).

Of course you'd need a very good AC->DC12V inverter.

According to the manual, one would have to solder a 12V P4 power plug to use it with P4 boards.

Cheers

sthayashi
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Post by sthayashi » Fri Aug 27, 2004 9:53 am

WTF, why can't they have this in ALL the Shuttle computers, rather than just the f***ing Zen? The stock Shuttle XPC generally comes with a 200W PSU.

hvengel
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Post by hvengel » Fri Aug 27, 2004 3:41 pm

They also have this one http://www.mini-box.com/pw-200.htm which is for ATX mother boards. No need for an adapter. The units are rated for 200 watts continous and about 300 peak. This is enough to handle all but the most power hungery machines.

For a 12 volt supply I would suggest the Astron RS-35A which is rated 25 amps @ 13.8 volts continous (345 watts). This unit has an internal adjustment for voltage and it can set any where from 11v to 15v. The Astron unit has no fan. It is available from HRO at http://www.hamradio.com These have been in production for many years and are highly regarded with some units in daily services for 20 to 30 years. If you want to get a better price these are generaly available on ebay.

PhilgB
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Post by PhilgB » Fri Aug 27, 2004 5:17 pm

What kind of brick do you need for these? Do they provide them?

gksam
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Post by gksam » Fri Aug 27, 2004 5:35 pm

hvengel, thanks for the lead on the powersuppply unit. now if only i could scrounge the funds to give this a try :)

hvengel
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Post by hvengel » Sat Aug 28, 2004 11:48 am

Yes this route is not cheap if you need more than about 150 watts. Buying a new RS-35A and the dc to dc supply plus the hardware to wire it up will run you a little over $200 ($150 for the RS-35A and $50 for the dc to dc unit). If you don't feel too unconfortable buying used you should be able to get a RS-35A on ebay for under well under $100 (current completed items on ebay $45 to $96).

The thing to watch for is that some (perhaps 5%) of the Astron units will have some transformer buzz. If you buy a used one and can inspect it before you buy then you can have the owner power it up for you. If you buy new then you should be able to exchange it if it has a buzz. These are available from any place that sells radio gear. So as long as you are not out in the middle of nowhere you should be able to find a local supplier.

jamesavery22
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Post by jamesavery22 » Tue Aug 31, 2004 12:44 pm

Shuttle wont use these because they cant provide the rails needed to power a real P4 board and other components.

The 200w rating is a little high.

I thought of the same thing and hunted for one on ebay. Someone else also had the same idea and bought a brand new one and tried it before I got a chance to, luckily. He was selling it on ebay because he could power the board but not much else... not even his HD if his proc went at full load for too long.

hvengel
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Post by hvengel » Wed Sep 01, 2004 11:47 am

Was the problem with the DC to DC supply or with the brick that was being used?

"The 200w rating is a little high."

Are you saying that the specs for the DC to DC unit are not correct? The specs say it will do 200 watts continous (actualy 204) and almost 300 peak. But if the spec is not correct then all bets are off. On the other hand if you don't pair up the DC to DC unit will a brick that can handle these power levels it will not work either. Bricks that have enough power are fairly expensive as well as being large and heavy.

jamesavery22
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Post by jamesavery22 » Wed Sep 01, 2004 12:12 pm

He was selling the 250w 12v brick with it. Came from some Dell Laptop.

By 200w sounds a little high Im talking abotu the rail ratings.

They say "Max Power = 205 Watts" but dont say how they calculate that which is where the BS lies.

Most companies rate the "Max Output" to be the +5v and +3.3v together.

So for instance a 250w Antec's close to real world max is 185watts. Thats the +5v and +3.3v rail combined. Now they list the +5v +3.3v and +12v combined (230watts) but that would never happen on most PSUs. You could max the +5v and +3.3v and not put a load on the 12v 24/7 and most PSUs will run. But if you max all three for a long time more than likely something will catch on fire.
anyways... look at the rails of Antecs 250watt PSU (link)
All max loads
+5v 25A
+3.3v 20A
+12v 13A

now the PW-120
"Peak" not Max
+5v 10A
+3.3 10A
+12v 13.5A

The 12v rail is decent since its not doing anything with it... So that max is whatever comes from the brick. It doesnt even regulate it.
But its noteworthy the regulation is pertty good on the lines, +/- 3%.
The Peak and Max ratings are weird though. Im assuming they put Peak as what it sounds like, a load it can provide for a second but thats it.
But even with the Peak, combining the +5 and +3.3 you only have 83watts... And if you look at Max Load (probably what its designed to run at) thats pretty weak.

But I've never seen a schematic of these things so there are things not mentioned yet.

namely how the 5v and 3.3v rails wont act like a normal PSU.
In a normal PSU they share lines on the transformer with the +12. So naturally a load on one will effect the other.
With this the only way a 3.3 or 5v load would effect the 12v load is if the combined load was hitting the max output of the brick.

Still, all that said the specs are just a little weak so dont be surprised if it cant run a 3ghz P4 with some components.

But hey if it works Id pick one up in a heartbeat.

hvengel
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Post by hvengel » Thu Sep 02, 2004 4:42 pm

Yes I see what you are getting at. The DC to DC unit is the weak link. I think it will work if all of the components are carefully selected. So no high end graphics cards, a mobil processor and one HDD looks like it would work but not much more. This could still be a fairly powerful system but not a gaming machine or high end workstation. They say on thier web site that it will work for a P4 system. P4 systems draw a lot of power from the 12 volt rail and as you pointed out this is only limited by the AC to DC power supply not the DC to DC unit.

jamesavery22
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Post by jamesavery22 » Mon Sep 06, 2004 8:38 am

hvengel wrote:Yes I see what you are getting at. The DC to DC unit is the weak link. I think it will work if all of the components are carefully selected. So no high end graphics cards, a mobil processor and one HDD looks like it would work but not much more. This could still be a fairly powerful system but not a gaming machine or high end workstation. They say on thier web site that it will work for a P4 system. P4 systems draw a lot of power from the 12 volt rail and as you pointed out this is only limited by the AC to DC power supply not the DC to DC unit.
I agree if you pick all lv stuff like a 2.5" laptop hd, laptop cdrom, and nothing else you could probably get away with a 2.6 or maybe a 2.8ghz p4. But I dont think many ac/dc power bricks have very tight regulation. THe ones Ive cracked open dont have any huge caps to do so atleast. Plus the more the DC-DC unit regulates the 3.3v and 5v the crappier the 12v line is going to get...

hvengel
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Post by hvengel » Mon Sep 06, 2004 12:00 pm

You are probably right about the kind of bricks that are shipped with laptop machines. But you can get really powerfull tightly regulated 12V DC power supplies that are designed for radio transmitters that will handle any PC that exists. See my posts above for some examples. Not cheap and big and heavy. So the real problem is the DC to DC unit.

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