running 120v AC off of your powersupply?

[impact]

Alright, so i just finished building my own water cooling system...
Right now its running on a waterblock i made out of an old dragon orb fan, an aquarium pump, pushing 120gph, no radiator attached for now, im just filling the res. with ice for the time being....
im posting because i have 2 questions...
1: I have a heatercore to use as a radiator, but it is a bit too big to fit in my case, does anyone know where i can get a CHEAP heatercore (or small rad) that would possibly fit in my case? (case is a Antec Soho Server 1000 series)

2: (the bigger of the 2 questions)
My pump uses 120v AC (just like most), but i dont want to have to plug it in every time i go to turn on the computer... or have to leave it running all the time my machine is off... I want to somehow hook it up to my powersupply, so that when the powersupply is on (comp on) then the pump is running...
I have seen PCI cards that do this, but that costs like 25$, and im trying to make this a cheap-o rig...
anyone know of any other way?

Thanks in advance
-Dan

 

[mata2974]

a chevette heatercore will fit your case at the front and is a good performer.
You need a relay switch in order to turn your computer and pump at the same time. If you had not used the search feature there are numerous threads on where to buy it, how to set it up. One place I know you can buy one is Radio Shack, if you live in USA or Canada I am sure. Welcome to the forums!!!!!!!!!!!!!

 

[Yuriman]

The 86' and 87' chevette heatercore is usualy the core of choice here. Again, you need a pump relay to turn the pump on when you start your computer. I leave mine on 24/7, although my pc is usualy on 24/7 anyway.

 

[squeakygeek]

You could buy a relay at radioshack and wire it to your 12v line.

 

[Graystar]

You can get a heater core on ebay. They're always popping up:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33548&item=2450762355


Here's a less expensive commercial kit:

http://store.pcpowerzone.com/pureswkit.html

Buying all those parts separately costs more than 18.00 bucks. If you have spare power cords and broken PSUs that you can cannibalize for connectors, then you can just buy a relay. You also need a diode.

 

[squeakygeek]

You can get a heater core on ebay. They're always popping up:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33548&item=2450762355


Here's a less expensive commercial kit:

http://store.pcpowerzone.com/pureswkit.html

Buying all those parts separately costs more than 18.00 bucks. If you have spare power cords and broken PSUs that you can cannibalize for connectors, then you can just buy a relay. You also need a diode.

What's the diode for?

 

[Thornbrand]

I'm no electronics expert (by any stretch of the imagination), but I believe it's fairly common to place a diode across the coil of the relay, Squeaky.

My understanding of this, is that when the coil that engages the contactor in the relay disengages, the collapsing magnectic field generates a charge that is in reverse polarity. Now, I'm guessing that most power supplies would handle this backwards spike of current just fine, but with sensitve (and often pricy) electronics in the circuit, the diode is sort of an assurance that no damage or problems could occur.

The diode will only allow current to flow in one direction, so when the coil field collapses, it basicly just acts as a shunt, or short, effectively dissispating any voltage spike that might occur.

If I'm off base on this, someone please correct me

As far as wiring up the pump, Impact, I don't see why you couldn't just wire it to the switch on the back of the power supply (provided it has one, most do.) Any time that switch was on, your pump would run, though you could still power down the pc with the switch on the front of the computer (and the pump would stay running until you turned off the powersupply from the switch on the back of it.) In this fashion, the PC simply couldn't be turned on without the pump running.

Only drawback to doing this instead of using a relay, is you'd have to crack open your power supply and do some soldering. If you're not real comfortable doing that, using a relay would be a better alternative.

 

[Graystar]

What's the diode for?

Goes across the coil leads. When power goes off, the inductance of the coil will send a reverse charge down the wires. Could possibly damage some sensitive components.

Look here to see the wiring:
http://www.procooling.com/articles/html/ph_s_guide_to_wiring_pumps_-_p1.php

 

[rogerdugans]

Not sure about how to set up the relay- always meant to make one of my own but never got around to it.

I do have a Swiftech relay that I still use and it is nice to not have to deal with turning the pump off separately.

I have soldered the pump leads to the power supply internally and that does work quite well although you have to use the switch for on/off. Good safety though! STANDARD DISCLAIMER- Be very cautious if you open up a psu: there are capacitors that can hold enough of a charge to kill you.

Chevette heater cores are a common and very good choice: great performance at a great price.

 

[impact]

funny story, saw that ebay posting a little while ago, and realized... i think i have a chevette heatercore... or something VERY close, my dimensions are VERY close to those listed...
anyone have ideas on getting it inside my case?
i cant find a nice place...

 

[Xaggerate]

An alternative to the relay is a power strip.....I'm going to run my pump (as well as the rest of the computer) off a standard power strip that basically turns everything on and off at once..just a thought...

 

[Graystar]

If think if you use a solid state relay you can forget the diode. Also, SSRs are smaller and more reliable.

This one can be operated from the 5V rail and can handle the power of just about any pump you'd want to use.

http://www.jameco.com/cgi-bin/ncomm...1&prrfnbr=3323&cgrfnbr=722&ctgys=503;523;722;

 

[Cyrix_2k]

I wired up my relay without a diode. Guess I should add one then... (BTW, the relay's $4 at Radioshack)