View Full Version : cheap psu's for 12V tec's........
sandman
11-03-2003, 02:37 PM
I was wondering, if I get like a couple fortron 350watt psus, and mod them to run together, and it would be like 36 amps on the 12V line, if i could use it to power a 226 watt pelt?
I've heard that you also need a load on the 5v rail, what coudl I use to get a load on the 5V rail if it would even work to begin with?
KnightElite
11-03-2003, 06:42 PM
It would probably work quite well. For the 5V line, you can just use a 1 Ohm resistor that can handle 5A, or a 5 Ohm, 1 A resistor.
Why would you need to load 5v line?
I am using Chieftec 350watt psu as stand alone power supply for 80watt tec (MCW50-T) and around 7A of fans, all feeding from 12v line without any other loads on PSU and it works fine...
You'd need only two fortrons (one has 12A 12vline right?) just make sure you are looking at sustained amps not pike values :)
TheDogFather
11-04-2003, 05:49 AM
You should take a look on Ebay for old server supplies, no one seems to want them.
I bought a supply with 40 amps on the 12v line, for £16 shipped.
TDF.
Originally posted by Jabo
Why would you need to load 5v line?
Because the primary output from an atx is 5v/12v tied if you stick a huge load on one and not the other it gets all confused and blows up prematurely :rolleyes:
Even my dogs danglies smps power supplys have to have a 5v load, although its clever enough to turn itself off if it hasnt to stop it blowing up.
]JR[
So why my one hasn't blown up yet?
EDIT: And why in specs 3.5 and 5 volt lines have combined max wattage and 12v line has separate wattage?
Its more likely that 3.5 and 5 volt lines are conected than 12 and 5 ... imho :)
99% of powersupplys are 12/5 linked. Yours might be otherwise.
Measure the voltage coming down the 5v and 12v lines with a load just on one ;)
]JR[
Hmmm, gotta buy myself multimetr first :)
maybee in two weeks time when $$$$ come in...
sandman
11-04-2003, 04:13 PM
I don't have an ebay account, but i might have to get one if they are that cheap.
If not, i'll go the fortron psu route, and get some big resistors.
Would I need to heatsink the resitors, if they are taking up that much juice?
KnightElite
11-04-2003, 10:06 PM
No, not if you get a resistor rated for that current. They will be rather large, and not likely to need heatsinkage. May get hot though ;).
sandman
11-05-2003, 12:58 PM
Alright. Thanks Knight, you've been very helpful with my whole getting into TEC's process.
sandman
11-11-2003, 03:11 PM
I just thought of another thing.
Some people have said that thier wires get very hot when running a big pelt through them, so do you think the normal molex connectors would be strong/big/whatever wires to run a 226 watt pelt on?
KnightElite
11-11-2003, 06:08 PM
Originally posted by sandman
I just thought of another thing.
Some people have said that thier wires get very hot when running a big pelt through them, so do you think the normal molex connectors would be strong/big/whatever wires to run a 226 watt pelt on?
I use 12 gauge wire (about 3 times the diameter of the standard PSU wires), and it stays pretty cool. When I used standard PSU cables though, they got warm, and the cables that come with the TEC will also get really warm. Make sure you get a good connection with your soldering job as well, the soldering joint can get to be burning hot. Personally, I would recommend some larger diameter wiring.
sandman
11-11-2003, 07:30 PM
Alright, how would I integrate that into the power supply then?
KnightElite
11-11-2003, 09:21 PM
Well, I just re-read the thread, and given that you are using an existing set of power supplies, you should be fine with the existing wire, since it is a real pain in the ass to change it. Sorry, I was thinking you had a dedicated PSU, in which case there are usually screw mounts.
sandman
11-12-2003, 01:09 PM
hmm..alright, it won't get hot enough to melt the plastic insulation around the wire will it?
Like it could get warm, but not hot, right
Another thing, this isn't the method I was going to use, but would it work ok?
http://www.procooling.com/articles/html/sharing_the_load_between_psu_s.php
you take that, and just basically combine the two 12V lines of each psu without the board and stuff, and just use it almost like a big Y-splitter going from both PSU's to the pelt?
KnightElite
11-12-2003, 04:47 PM
Yeah, I've read it. I actually used the method you describe in the past, and it worked, except it was overworking the AT PSUs I was using. They describe in more detail how to do it in an older article on procooling:
http://www.procooling.com/articles/html/linking_multiple_psu_s_as_one_.php
sandman
11-12-2003, 04:54 PM
I read that too, but honestly didn't quite get what he was doing.
But just using the two with my "y-splitter" method I described above is what I will probably.
Have a 350watt sparkle coming. It's going to get tested against my 450watt allied, then the weaker is going into this project.
Pimpsho
11-14-2003, 06:19 PM
what about the meanwell 320...do i need something feeding off the 5v line or is just havin the 226wat tec on it ok?
sandman
11-14-2003, 06:20 PM
with the meanwell, you don't need anything else.
In fact, I think it might just give out one line, but I'm not sure.
KnightElite
11-14-2003, 11:33 PM
Originally posted by Pimpsho
what about the meanwell 320...do i need something feeding off the 5v line or is just havin the 226wat tec on it ok?
With the meanwell, you don't need to do anything else, it is designed for this type of application. He is talking about PC power supplies.
Pimpsho
11-15-2003, 08:53 AM
ya i was making sure;) thanks for the heads up guys
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