How to wire 3x PSUs?

[Jakalwarrior]

I am just building a bit of a novelty piece. A drink cooling cup holder. The pelt will be run close to max power but for no more than a few minutes. Load will only be that of a warm beer that needs to be cold again Hot side will be air cooled. I only have to keep it ~60 - 65*C to get the cold side where it need to be. I assume I will need to run a pot pretty badly since 450 watts (15x30) would be a pain to dissipate with air.

Bought a ~280 watt pelt that maxes at 16 volts @ 32 amps. If I were to plug it in to a 12v line on a single PSU it would draw ~24 amps if my math is right? Well this is for a low budget side project so its not going to get an expensive ATX PSU or a single output DC PSU. Instead I want to wire together 3 really cheap crappy PSUs and combine their 5v rails to make one 15v rail with lots of amps. Probably out of old OEMs or cases that came with psus. You know, crap I can get for free. Even if I had to buy them I could get 3 PSUs with 30+ amps on the 5v rail for sub $30. How do I wire this though?

Should I use the molex connectors or the 5v on the main plug? or does it matter? Should I use more than one molex line from each PSU to overcome resistance and reduce the heat of the wires? Should I just strip the ends of the wires and combine them all and connect that to the TEC? also, what should I do for ground?

I do know the whole project would look MUCH cooler using just one small PSU. If it works well I may go ahead an invest in one but at the moment I can't bring myself to buy a $100+ PSU for a novelty project.

[Delfistyaosani]

If I were u.. I'd cut every +5V wires and every-1 GND wires of all 3 PSU's, connect then in a row just like batteries, interconnect every green line to corresponding ground and pick one +220V wire for every PSU with one power button to turn on/off them at the same time

Here u have +15V with 34A that is pretty good

However to keep one cup of beer cool even USB power is enough. So my advice is to get a metal beer container, attach some 10-12V 50W TECs with intel stock coolers on hotsides, power them undervolted, with one +5volt PSU, put this everything into a computer case and u'll have a realy Beer Server with always cool beer

Sorry if my English isn't understandable but hope u'll get it :P

[drnip]

You thought about trying this?

http://www.performance-pcs.com/catal...oducts_id=2850

[Jakalwarrior]

If I were u.. I'd cut every +5V wires and every-1 GND wires of all 3 PSU's, connect then in a row just like batteries, interconnect every green line to corresponding ground and pick one +220V wire for every PSU with one power button to turn on/off them at the same time

Here u have +15V with 34A that is pretty good

However to keep one cup of beer cool even USB power is enough. So my advice is to get a metal beer container, attach some 10-12V 50W TECs with intel stock coolers on hotsides, power them undervolted, with one +5volt PSU, put this everything into a computer case and u'll have a realy Beer Server with always cool beer

Sorry if my English isn't understandable but hope u'll get it :P

But massive overkill is so much fun. My dream would be to have it power on, dim the lights, and freeze the thing in seconds though I think that is a bit unrealistic considering a can or bottle won't conduct well enough for that even if I had pure alcohol surrounding the can / cup to enhance it and prevent frost.

[Delfistyaosani]

Why pay 2$ then u can do that with one interconnect between green and black wires?

But massive overkill is so much fun.

What about a frankenshtein-like device with an "input" and "output", u put "input" into a bottle with warm beer, push a button, liquid goes through your frankendrinker and fills your cup with ice-cold bdrink in seconds?

[Jakalwarrior]

Why pay 2$ then u can do that with one interconnect between green and black wires?



What about a frankenshtein-like device with an "input" and "output", u put "input" into a bottle with warm beer, push a button, liquid goes through your frankendrinker and fills your cup with ice-cold bdrink in seconds?

Another idea ive been thinking of. I could cool the hot side of this with ice water and super chill some everclear in this thing I'm not sure what I would do with -30*C alcohol but I am sure I can think of something. Maybe pour some in a fruity girly drink and see if it turns it to slush.

[Delfistyaosani]

No idea what u'll do with -30*C but I think u can add a temperature selector U can have a very cool 1 or 2-liter tank with kinda mixer and a temperature sensor inside, when it fills with liquid TECs will work at full power until your alcohol reaches requested temp, then flushes out

For this u'll need two pumps, a thermo sensor, a microprocessor, kinda Touchscreen LCD (most crazy part in your beer server )... Assemble that into an apple mac pro case and write iDrink with glossy silver paint I think that would be a beast

smth like



and remember - TECs can heat up your liquid too, so be sure your server is fully compatible with Sake™ technology

[Jakalwarrior]

Not just Sake my friend (though I do love me some good sake), it could make coffee! for when you wake up in a strange place and need to get both eyes open quickly!!!

Wish I had it right now, my co-workers are trying to freeze me. I am running Orthos to try and get a bit of heat under my desk.

[Delfistyaosani]

for 100+ *C using TECs is nonsense I guess, u can simply "integrate" a water boiler as a component, TECed tank with thermal sensor is good because you can get your alco from about -20 to 50 degrees with accuracy of +-2*C in the same tank, but it isn't too easy to take out and wash like a cup, so for coffee more efficient "component" can be added.

when you wake up in a strange place

As we "have" a touchscreen LCD lets add a GPS navigator too

Just imagine u wake up no idea where, power on your favorite "toy" and "U've been driving like crazy last night, so now fallow this path not to be spotted by cops"

really lovely

[Jakalwarrior]

Think I figured out the power issue. Ordered a PSU from an HP server that is 575 watts with it being made to put all of its power out on the 12v line. Was 18 or 19 bucks shipped so it met my cheap criteria. Now I just have to figure out how to get the power out of it since it has some sort of weird hot swap plug that looks like it belongs in a Nintendo game cartrige. One step closer to my no more hot beer dream!
If my E7200 were any better I would be thinking of sticking it on there but past 3.8ghz it starts asking for lots of juice. Takes 1.29 vcore to get 4.0ghz

[Delfistyaosani]

Can u take a picture of that and post here? I regularly use computer and other sort of "impulse-driven" PSUs in many things so think I could help you figure that out

[Jakalwarrior]

Ordered this http://www.compuvest.com/Desc.jsp?iid=844250

No good pics of the connectors. On ebay though:
http://cgi.ebay.com/HP-COMPAQ-DL380-...#ht_500wt_1182
http://cgi.ebay.com/compaq-HP-prolia...#ht_649wt_1161

[flak-spammer]

Oh dear I can see this ending very badly, I would suggest finding a Meanwell or something instead. Much less chance that something will ignite or explode.

[DonNiger]

Oh dear I can see this ending very badly, I would suggest finding a Meanwell or something instead. Much less chance that something will ignite or explode.

No, this is fun

I'm just in the middle of connecting two redundant PSU in a row for 12/15/17/24 outputs (24A).
If I would have one more, I would try to have 36v (from 12 to 36 @ 3v steps) as well. I am always short of power.

[Delfistyaosani]

Don't u have any digital camera? Or at least doesn't your cell phone take photos?

[Jakalwarrior]

Yeah, but fedex is currently in possession of it until next Wednesday (I asked for USPS, they are faster. They gave me fedex )

[Delfistyaosani]

Whatever... u can determine where to connect using a multimeter

I would recommend attaching ampmeters to all PSUs (hope u know how to use an ampmeter) to avoid any unwanted overload

[flak-spammer]

Huh, an ammeter (not ampmeter) isn't going to help with unwanted load. A fuse would stop overloading, and simply put it may be a good idea for the sake of safety although it depends on how you want to do things.

[Delfistyaosani]

Ok ok.. my English is horrible

However a fuse will just burn out and rescue system, but a combination of digital ammeter and PWM controller could simply prevent amps from exceeding a given value

[Vinas]

I smell doom.

[Jakalwarrior]

We shall see. When I get home the PSU should be waiting for me. I'm just hoping I can figure out how to turn it on.

Only heatsink I have to slap on it at the moment is a stock AMD one but I'm going to have to figure out something better. Even at only 12v I can probably count on 300+ watts of heat on the hot side.

[zipdogso]

Ok ok.. my English is horrible

However a fuse will just burn out and rescue system, but a combination of digital ammeter and PWM controller could simply prevent amps from exceeding a given value

WOW...I'd love to see a ammeter save a circuit from an overload with or without a PWM controller...

for goodness sake all they do is measure....won't do a darn thing for an overload and if you mean allow you to see an overload I don't really expect anybody is going to study a ammeter all the time a circuits running...an overload is an overload...Puff.....

Buy I suppose this idea is about par for someone who believes they can make a working, efficient TEC from 2 toolbox scraps of dissimilar metals....groan.

[Jakalwarrior]

here is what the pinout looks like
http://pictureposter.allbrand.nu/pic...s/DSC00113.JPG
No idea how to power the thing on and no luck on finding pinout diagrams online. Ug....

[DonNiger]

Not tested in real life yet but cheap server PSUs for TEC
The switch cost twice as much as the PSUs
Couldn't find the third one for 36V

12V, 15,3V, 17V ja 24V: +20A

[Delfistyaosani]

for goodness sake all they do is measure....won't do a darn thing for an overload and if you mean allow you to see an overload I don't really expect anybody is going to study a ammeter all the time a circuits running...an overload is an overload...Puff.....

I have heard some about Britain's brains but what I see is more than expected

Listen now... an ammeter isn't only a device with dummy gauge, have you ever heard about digital or voltage-output ammeters? Ok, they also have no idea what to do with PWM, PWM controller has no idea when to start "throttling" BUT there are some "magic" chips called microcontrollers that can read ammeter value and decide what to do with PWM, if no AVR / PIC knowledge an analog circuit can do the same job, with some operational amplifiers but personally I don't like analogs when have a digital one

AVRs have ADC's so it's quite simple to get amps value, controlling a PWM is also trivial (an AVR can modulate a quite good PWM signal so all u have to attach is a powerful MOSFET).

The program could look like

chip_init();

pwm_level = 1; // 0..1

const float amps_limit = 15;

float amps_level;

while(1)
{
amps_level = get_amps_level();
if(amps_level>amps_limit)
{
if(pwm_level==1)
pwm_level = amps_level / amps_limit; //some sort of approximation
else
pwm_level-=0.01; // still overloaded?
}
else
if((amps_level<amps_limit)&(pwm_level<1))
pwm_level+=0.01; //less load? lets add some
}

An analog circuit could look like this:



As you see there's no PWM controller, but this will act like a good PWM too, because there is kinda recursive relation between controlling and controlled element: At first we need an ammeter which generates corresponding voltage with a constant ratio. 1/10 V/A would be nice (0.1 volt per 1A) then we need to apply reference voltage to the second input of our analog comparator - limit is the point where ammeter output exceeds reference, for example if we have an ammeter with 1/10 ration and 0.5 volts on reference 5 amps will be the limit, cuz in that case comparator output is null and MOSFET switches off. Of course after that AMMETER output will be zero too and MOSFET is turned on again.. some people call this "negative feedback circuit".

1. My English is too bad so I'm not sure everything's understandable
2. I haven't tested this yet so I can't guarantee that it works