Mod case fan to run off of a AC/DC converter?

[mdubrow]

And now for something completely different....

I'm looking for a quiet fan--or at least a fan whose speed I can vary easily--to keep the components in my entertainment center cool and comfortable. Here's the rub: when I search Google for quiet variable speed fans, I get links to computer case fans! (Antec, Coolermaster, Yate Loon, Nexus...you get the idea.) Well, these fans are either 3-pin or molex connector types that are designed to be plugged into a typical computer PSU or motherboard fan header. But since these fans are designed to run off of DC, shouldn't it be possible to connect them to a standard 12V AC/DC converter and, more to the point, how would I do that? I tried searching Google for ideas, but came up dry.

Thanks!

 

[Zepper]

It's not that hard. 1- Get the fan you want, from bgmicro.com et al. 2- Get a 12V power supply to match the fan (Amp rating), from bgmicro.com et al. 3- Get a Zalman Fan Mate (from svc.com or jab-tech.com et al. to control it (not needed if you got a fan that comes with a controller). 4- Cut the DC connector off the power supply and (observing proper polarity) splice the wires directly to the fan mate or other fan controller (or if you want a proper plug on the power supply, jab-tech.com, svc.com et al. carry contacts and shells for the standard 3 and 4-pin connectors). 5- Plug the fan to the FanMate.

Done.

.bh.

 

[mdubrow]

Thanks, Zepper.

Quick follow-up: You mentioned, when cutting the DC connector off of the power supply to "observe proper polarity": what should I be noting when obverving proper polarity? Specifically, what will tell me which wire to connect to red and which to black?

Thanks again!

 

[grimlykindo]

Yup, all you gotta do is this:

1. go to compusa and buy some off brand $10 psu (I've seen $5 ones)
2. fans of your choice
3. like stated above: a fan contoller of some sort


It would be cool to make a custom entertainment center with its own PSU! You could add as many fans as you wanted. you could even add some blacklights or something for a cool effect.

Now you got me thinking...

 

[natto fire]

Originally posted by: mdubrow
Thanks, Zepper.

Quick follow-up: You mentioned, when cutting the DC connector off of the power supply to "observe proper polarity": what should I be noting when obverving proper polarity? Specifically, what will tell me which wire to connect to red and which to black?

Thanks again!

If connecting to a computer PSU you will want to connect the red wire on the fan to the yellow wire on the PSU (for 12v) and the black wire on the fan, to the black wire directly next to the yellow one (for 12v ground). The wires on the fan might be a different color, but they are usually the standard RED/BLK, and are sometimes labeled on the fan itself. If it is a 3 wire fan the yellow or blue wire is for the sensor signal and won't be needed for your application.

 

[mdubrow]

Well, I wasn't planning on using a computer PSU because it'd take up too much room in the cabinet. I was intending to use a small wall wart-type of 12V AC/DC converter. I have one (a few, actually) that I don't use lying around....

Going back to the "proper polarity" remark that Zepper made, if I connected the wires improprerly wouldn't the result be the fan runs backward, no? I'm not going to blow anything up, right? Let's just say I had a bad experience confounding AC and DC once and the result required a helluva lot of fire engines.

 

[Zepper]

Most fans these days are reverse polarity protected with a diode, so if you have it connected backwards, it just won't run.
. Most of the wall-wart type power supplies have color coded wires or one wire has some kind of marking on it (white stripe, molded-in markings, etc.). IOW, there should be a way to tell one wire from another. Then it's just a matter of determining which is pos and which is neg. Generally the supply will have a mark on it like this Neg- -----(o-------- Pos -pretend that the left paren wraps more around the o like a C . Which means that the "pin" (or outside contact) is Negative and the "tip" (or inside contact) is positive - which is the most common configuration. Now you just have to determine which wire goes to which. All this is moot if you have a nice cheap multimeter (can be had for under $10. these days). No guesswork involved there... Or if you wish to assume that your fan IS diode protected, then just try it one way or the other. If it is not diode protected and you have reverse polarity, it will run in the opposite direction of the little arrow molded into the fan frame (at least for a while ). We all know about "assume", right?

.bh.

 

[mdubrow]

Thanks again, Zepper! Good information. Gives me a great deal of comfort to know that the worst damage I can do is to kill the fan. For $10, I think I'll just buy an extra fan.