Using pc fans for cooling - Dc/ac 12v/120v ?

J

JumboAg99

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[I'm probably going to feel really stupid after seeing the responses to this, but I am an Aggie so bear with me...

I spent 45 minutes in Fry's today looking at fans over in the PC parts area. I only found a couple that were 115/120V AC. Most are 12V DC with the standard 4 slot power plug to connect to a PC power supply.

What do I need to buy to use these fans? I looked in the AC/DC converter area and didn't see anything that looked like the right equipment.

Anyone that's done this before... HELP!! I need to know what to buy, how to wire, etc....]
 
[Get the 12V PC case fans you were looking at. You can get 110V AC to 12V dc converters at Radio Shack (home depot also has one). But before you make the trip, check to see if something in your house that you may no longer be using has a converter. For example, my broken linksys router used a 12 V converter.

The thing that you need to look for on these converters is how much current they can handle. My case fans run at 150mA so I've hooked two of them up to one converter that can supply 400mA.

The case fans have some flexibility in the power supply. If you want to run it a bit lower speed, you could use a 9V supply. I think this is basically how the temperature controlled case fans run (they resistor divide down the voltage).

Also, Marc has posted some info on his website.

Hope this helps,

-soji]
 
[I ordered my fans from http://www.alliedelec.com/
You can get any size fan, speed, or noise level that you want here. Fast delivery too.

I went with the a 110v (stock # 592-0290, mfg # OA109AP-11-3WB), so that I would not have to worry about an adapter, just connect the wires to an old extention cord with the female cut off.]
 
[Agree with Soji,

Those AC fans will surely work but you can buy you the cheapy DC ones at frys (don't worry about the connecters) buy you a AC/DC converter at fry's. Snip the ends off both. Either buy a connector and put the wires in the connector and use it (this actually requires a tiny amount of skill) or do what I did and simply twist the wires together add a very large amount of electrical tape and your done.

You can get at least 3 fans and the converter for under $20. Do be sure to get a high power converter. I have a 100mA one so I can hook a lot of fans/moonlights up if I need to.

I knew that Aggie Electrical Engineering degree would help me out!

Gig Em]
 
[I went with 110v fans, why bother with a converter if you don't need to? Try to find a 110v fan that moves the most CFM and is the quietest.]
 
[The fans I understand (saw plenty of 12V ones). The part I'm unsure about is the AC/DC converter. All of the ones I saw at Fry's seemed to be designed to do exactly the opposite of what I wanted. (Take DC power and use it on an AC device instead of take AC power to run a DC device)]
 
[Here's my 2 cents.

12VDC fans are generally pushing less air compared to 120VAC fans. Most computer case fans are 80x80 mm, and are generally smaller than AC fans. To push the same amount of air, the smaller fan has to driver harder, thus makes more noise.

Since I don't like the noise, or the bulky adapter, I use one 120VAC fan. I don't remember the specs on my fan, but it pushes twice the amount of air when compared to the normal computer case fan. $20 at Radio Shack.

There are risks to AC fans, however.

1. All AC fans at Fry's and Radio Shack are not designed to work in a wet area.
2. If your fan gets dropped into the tank, all of your life stocks are gone. And if you don't know how to handle the situation, you could be gone, too.
3. If you are not careful with the wire connections, you could get shocked.

All of these are easily handled. Make sure you securely mount your fan(s) in the canopy for 1 & 2. Twist, or better yet, solder the wires together, then use epoxy to seal the connection.

Hope this helps.]
 
[I replaced all of the wall sockets in the tank area with GFCI outlets. In theory, the breaker will be tripped if anything gets wet. - Though I'm not planning on tossing a hair dryer into the tank to test that.]
 
[Thx.

I ended up going back to Frys and bought 2 3" DC fans and a DC/AC adaptor.

All of the 4" fan's had a noise level of close to 50dBA. The two 3" ones I bought push about 40CFM and are only 25dBA.

I bought a power supply that can provide 1800mA, so it has plenty of room left in it if I choose to add more fans later.]
 
[I used a couple of 23 db fans and it worked well. There is no reason you couldn't add more. I ended up putting them on a timer to avoid getting the tank too cool.]
 
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