Need fans but must be 120v ac

impending · Post by **impending** » Fri Dec 21, 2007 5:43 pm

Hi Folks - first post here !

I need to vent the enclosure my pc sits in but the issue has me stymied!

The situation is - I have a P182 that generates a fair amount of heat from an oc'ed Q6600, 8800 gts and 4 drives. I have no issue with the case cooling but the heat gets trapped in the cabinet in which it sits.

The cabinet is built in a corner - I have access to one side plus the front. The space around the case is approximately 3/4" on the sides 2" on the top and 3" in the back. In this space there is no way to keep cool.

My first option is passive by simply drilling multiple 2" holes on the top of the side but becuase of the amount of heat I'm thinking active cooling will be necessary.

If I could install 2 120mm fans into the cabinet side that may be adequate but becuase I'm just sliding the case into the cabinet they will not be connected to the motherboard so standard case fans won't work.

What I need is -

a converter from 120v ac to 3 pin or
fans that are 120v ac - preferably variable speed

Fans exist that are 120v but all I've seen are noisy beasts (40+ db) that do what they were intended - move a lot of air. I can't find any that are variable speed/noise. Within the cabinet the pc is fairly quiet but these fans will be much closer to my ears. I don't need silence just comfortable is ok.

I'm hoping someone here has built an enclosure and has already found a solution. Any help is appreciated.
thanks
jd

bonestonne · Post by **bonestonne** » Fri Dec 21, 2007 5:50 pm

hm, its really hard to say how helpful this will be, but you can buy 120v AC adapters to molex plugs. what you can then do is then run a molex to 3 pin adapter, and thats one solution done. however, i've only seen these adapters in packages with USB to IDE adapters for a quick hard drive fix.

another solution would be buying a 120v AC fan that's small-ish and then putting that in a hole as exhaust on the cabinet.

past that, i don't know what to tell you.

pingu666 · Post by **pingu666** » Sat Dec 22, 2007 7:25 am

ive got 2 120mm papst i think, AC fans, there noisey from what i remmber, u could hook them up to a light dimmer to reduce the rpm i guess

if you pay postage u can have them, where do u live?

impending · Post by **impending** » Sat Dec 22, 2007 4:35 pm

Hi bonestonne - funny, after reading your response I googled "120v ac converter" and the first hit is this thread hehe

but it did lead to this http://www.frozencpu.com/products/6084/ ... ZXwW#blank
which is exactly what I need to install any fan I want. I didn't know these existed thanks.

Hi pingu666 - that is a very generous of you to offer to send me the fans you have - very much in the Christmas spirit

I'm in California, the closest I've been to you is Staines! Anyhoo, looks like the converter will allow me to select quality quiet fans.

Actually, I'll try something else before drilling holes in the cabinet. It dawned on me that since the problem is the case is venting the heat to the back of the cabinet where it can't escape fast enough - I may be able to vent it to the front by simply reversing the fans. My case has 2 rear and one top fan venting out and a single fan in the middle front position pulling air in, not counting the 650w power supply venting out in the rear. I don't know if three fans in and one fan out will create any restriction due to positive air pressure but I don't see why it would and it certainly is cheap and quick to find out.

Thanks again for you help &

Merry Christmas !
jd

Elixer · Post by **Elixer** » Sat Dec 22, 2007 11:52 pm

Hmm... try some forum searches. I know there was a big thread on 120V fans. There are some 120x38mm fans I remember having better acoustic characteristics than most 12V 120x25mm fans. One easy way to get a low speed fan is to either buy a 220V fan and then run it at 120V or wire two 120V fans in series, which will give each fan 60V and run them at about 1/2 of their rated rpm and about 10db quieter than their noise rating.

pingu666 · Post by **pingu666** » Tue Jan 01, 2008 11:10 am

just chuck me a pm if u need them fans

ferdb · Post by **ferdb** » Tue Jan 01, 2008 12:57 pm

I can highly recommend the Sunon DP200A-2123XST. These are 230VAC fans, but will run on 120VAC at about 1300 rpm. They are exceptionally quiet for the airflow on 120VAC. You can buy them from allied electronics.

http://www.alliedelec.com/Catalog/pf.asp?FN=551.pdf

These fans are 120x38mm. These have metal frames and blades and are fairly heavy.

If you read through the following thread it also covers ways to speed control these fans with variable resistors and capacitors. This includes being able to boost the speed while still running on 120VAC by using capacitors should the default speed at 120VAC not be sufficient for your needs.

viewtopic.php?t=16393&postdays=0&postorder=asc&start=0

lm · Post by lm » Tue Jan 01, 2008 1:36 pm

How about a long extension cord from a molex on your PSU to standard 12V DC 120mm fans?

jhhoffma · Post by **jhhoffma** » Wed Jan 02, 2008 7:54 am

I know I've answered this question several times. Definitely stay away from 120V fans. You have much more variety and quieter running designs in the 12v arena.

All you need is one of these. and you can supply a DC fan with a discretely variable range of voltages. You will have to cut off the connector on then end and wire the fans directly, but it's easy enough to do.

Hope that helps.

klingenfelter · Post by **klingenfelter** » Thu Jan 03, 2008 7:35 am

I concur with jhhoffma. Use 12 volt fans with the radio shack or other AC/DC adapter. If you need to move alot of air with no sound, see my post some months back about ventilating a large cabinet with several thousand watts of heat and a silent PC inside. I used two 250mm fans. They cannot be heard in the listening room yet move several hundred cfm of air flow and keep the inside of the cabinet cool. I also supplly 12 VCD to the fans through back to back diodes so either in HT receiver (switched 110 VAC) or the HTPC (12 VCD) can supply fan power in case I forget to turn off one of thesee devices

See

viewtopic.php?t=42580&highlight=

and

viewtopic.php?t=42579&highlight=

Keith