I have a large Audio equipment rack that I need cooled...Can I just use PC fans?

Hey everyone,
I have a large entertainment center that has things like amplifiers, power conditioners, and Audio receivers in my home theatre. These things get EXTREMELY hot and I'm looking for a way to cool them down. They get so hot that they shut down...

This stuff really belongs on a professional rack with rack fans installed between each bay but I don't have the $1,000+ to buy a Audio rack and equipment that looks good in my house. (or the room either)

What I plan to do is just cut small square hole at the bottom of each shelf, install a metal screen over that, and then mount one of those computer fans so it can blow cool air over it. I have some questions:

1. How would I power up these fans? (I'd like to maybe make a switch I could screw on the side of the wood entertainment center that turns them on...) Is there some small power pack that could supply power for 3 or 4 of these fans simultaneously or something like that?

2. What would be the most quiet fan for my to buy?

3. Is there a way to hook up a thermometer so that these things can automatically go on? (I'm not too worried about this actaully, I'm fine with turning these on manually.)

Thanks all!

1. Some wall wart transformers will power fans, but most will not because they have an AC output. You could use a bridge rectifier and a smoothing cap on one with the voltage/amperage output you need.
You could also shop around for a notebook brick that gives 12 volts, and skip the rectifier/cap.
Switch>Transformer>Rectifier>Cap>Fans...I used parts scavenged from an old computer power supply, they work perfectly and easily take all the power you'd need for fans...don't skip the shrink wrap for any solder joints.
If you have plenty of room to hide it, you could just use the computer psu and put the switch between the green wire and any black wire on the 20/24 pin connector. Efficient, fanned, done.

2. I like the Noctua 1200 rpm fans personally, but the Scythe S-Flex's are decent as well as being a few bucks cheaper. Buy adapters that you can cut into to extend the wires, then you can retain warranty if you so desire.

3. The switch should be put before the transformer so it's not running all the time. You could easily put that on one of those remote control outlet accessory things from Home Depot/Lowe's, then you'd have a remote switch. Otherwise I'd use a cheap extension cord and put the switch into either conductor of the cord with the transformer at it's end. Make sure to use a 120v 3Amp switch or better.
Most (but not all) household thermostats work on 24 volts, but if you can find a cheap one that does 12, then you've got a ready-made solution.

Sounds like a fun project....hmmmm. That Dish receiver throws a lot of heat...

You could easily use 12volt 120mm fans connected to the said switch and powered from one of those 12volt plug pack type adapters .
You can get get them with the correct Amp rating that you would require and there not that expensive.

Back in the Day when I had a Similar setup, I had 100mm 240volt Fans 4 of them hooked up to a switch and Fan controller( similar to Dimmer for lights) and that cooled my cabinet fairly well.

True, radio shack, mpja, and electronic surplus all have 110 volt fans that you wouldn't need to transform.

Good one JS!

Look around for 110v AC fans but be forewarned they are not cheap.

I have been looking for a deal on a used enclosed rack for a long time (got 2 I am waiting for response on currently) and I am probably going to just use a Comp PSU instead of spending the extra $$ for AC 120mm fans (average 15+ USD per).

Once I get the rack I want (or end up building one) I am going to put a buildlist up of what I am doing/want to do with it and I will probably revive my rackmount thread.

Diggrr said:

1. Some wall wart transformers will power fans, but most will not because they have an AC output. You could use a bridge rectifier and a smoothing cap on one with the voltage/amperage output you need.

Click to expand...

Well if it outputs AC then it is not a transformer.

Transformer = AC to DC or vice versa


If you get a DC transformer you will need to calculate the amperage needed by your fans and get a transformer capable of outputting at least what the fans need at maximum


I have thought of doing this as well, but never got around to it.

I did however give a 12v server fan to my Mom for her in wall AV system.

By definition, yes. Tell that to my wall warts that just make a fan sit there twitching without turning. Most simply step-down the voltage, and lack the added circuitry that makes them output DC...I believe that is left to the charged device to include, like my 12v spot-light's charger that plainly says 13.4 VDC output, when it registers as AC on my meter and won't turn a fan.

And when you buy a simple wound core, the package calls it a transformer too..Go Figure!
Case in point:http://www.mpja.com/prodinfo.asp?number=7840+TR
look at the output listed there...

Adragontattoo said:

Look around for 110v AC fans but be forewarned they are not cheap.

I have been looking for a deal on a used enclosed rack for a long time (got 2 I am waiting for response on currently) and I am probably going to just use a Comp PSU instead of spending the extra $$ for AC 120mm fans (average 15+ USD per).

Once I get the rack I want (or end up building one) I am going to put a buildlist up of what I am doing/want to do with it and I will probably revive my rackmount thread.

Click to expand...

Wait a second, these can run off an old computer PSU?? I have a few lying around I can use... Do these fans plug directly into one of those 4 wire ports? If thats the case I think the PSUs I have must have 4 of those cables coming off of it...hmmmm

Neur0mancer said:

Well if it outputs AC then it is not a transformer.

Transformer = AC to DC or vice versa


If you get a DC transformer you will need to calculate the amperage needed by your fans and get a transformer capable of outputting at least what the fans need at maximum


I have thought of doing this as well, but never got around to it.

I did however give a 12v server fan to my Mom for her in wall AV system.

Click to expand...

Umm by definition a transformer is an isolation device and a step/up or step down of the AC. A transformer will not work with DC applied nor will a basic transformer output DC. It IS an AC output. It has no rectifiers, diodes, or caps to smooth the AC into DC.

A house doorbell is a prime example. It takes 120 VAC and steps it down to 30 or 18 VAC. It's still AC.

A AC/DC converter, power supply, etc etc, has a transformer in it, plus the required circuits to remove the negative cycle and convert it to DC.

I used to teach this stuff. It's more an issue of terminology than anything.

@ Conumdrum: Thanks for the clarity!

@TommyHolly: Yes you can use a computer psu, as I mentioned in the first post.
Make a cutout in the back of your cabinet to mount it the same as you would in a case. Puting a jumper on the 20/24 pin plug full time would let you turn it on and off with the power supplies own switch. If it doesn't have one, then put a switch into the jumper, and that will turn the psu on/off (standby actually, the psu will still have some power so be careful!!).
Heck, you could even power some CCFL or LED lighting in your cabinet too, easily.

Aluminum mesh (or the old pantyhose) filters on the intake fans will keep the dust out too.

Plug in your fans and go man go!

Sweet! Hey thanks!!

Any good links to where I can get those jumpers and switches to turn this stuff on and off? I should be able to daisy chain a bunch of these fans right?

Diggrr said:

@ Conumdrum: Thanks for the clarity!

@TommyHolly: Yes you can use a computer psu, as I mentioned in the first post.
Make a cutout in the back of your cabinet to mount it the same as you would in a case. Puting a jumper on the 20/24 pin plug full time would let you turn it on and off with the power supplies own switch. If it doesn't have one, then put a switch into the jumper, and that will turn the psu on/off (standby actually, the psu will still have some power so be careful!!).
Heck, you could even power some CCFL or LED lighting in your cabinet too, easily.

Aluminum mesh (or the old pantyhose) filters on the intake fans will keep the dust out too.

Plug in your fans and go man go!

Click to expand...

Jumpers are usually home-made. I have a 1" piece of 18 gage power supply wire that I stripped 3/8" off of each end, twisted tightly and tinned the ends with solder then bent in a U shape. The solder stiffened the wire to act as the psu pins do.
Just about any conductor that you can invent that won't short to something or fall out will do fine.
If you're not going to use the power supply again on a PC, just cut them from the 20 pin connector and wire your switch directly to them.

Again, if you're going to use the power supplies built in switch for on/off, or a remote switch, then use a jumper.
If you're going to power it on/off with the jumper, install a switch AS the jumper.

For 12 volt switches and a jumper switch, Performance PC's has a dizzying array of toggles: http://www.performance-pcs.com/cata...th=376&zenid=ddf95fd66b8fb374e87397cab0ac41bf

For 110 volt AC switches, I'd suggest Home Depot. Love that place. Wish they had apartments for rent there.

All of the wires that you aren't going to use can be snipped off clean and bundled with electrical tape so they don't short out to one another or your equipment. You could also install a small plastic project box next to the psu to cram them all into to forget they exist, yet keep them intact...leave out the drive powering molex's that you'd need of course.
And Yes, you can daisy chain dozens and dozens of fans to your heart's content. You have what, 150 watts to use on the 12 volt line? (varies by psu, read the tag).
A decent rule of thumb is 6 amps (72 watts @ 12 volts) maximum per wire from the power supply body, or 2 amps per connector, so they don't overheat and melt.

Here's a reference pic for ya (click the tiny one), showing both 20 and 24 pin plugs:


The Jumper or switch goes from the "PS_ON#" pin to any one of the black wires.

Anything else you need, just hollar!

Tommy,

I don't know if you have an electronics/hack shop/etc type surplus store around you, but you can get quite cheap AC fans that will move much more air. Sure you have to spend a bit of money, but if it prevents your equipment from crashing I would think its worth it right?

Plus you can get much larger AC fans instead of a whole ton of high speed noisy DC fans.

Tommy you saw my pics on AVS, I use a 12vDC wall wart to power mine, I run a light in series to let me know its on...(STAYS ON even if equipment is down...)....

I used a couple spare antecs with the LMH switch and run two 120s on low speed..

works great and you can't hear them.