Hello all

I'm not sure exactly where to start this thread but I thought that here was a good a place to do it as any.

I'm wondering if anyone knows of a way to power computer case fans - in my situation, 120mm ones but the connectors are the same on them all [i think] - without them being connected to the computer's PSU...

Why? you may ask........

And rightly so.

It's down to the fact that I am mounting them in a cupboard [create a hole where the circular area of the fan is, and screw the fan into the wood of the cupboard.

Given the limited budget i have - virtually zero - I thought this might be a useful way to extract air out of a cupboard. I think it could work out better than buying the presuambly expensive industrial type of ones I've found on the internet.

Of course, if it comes to the worse, i could attach them to PSUs of the computers inside the cupboards...

["computers in cupboards - are you mad?" Yes i am, but its a great anti-vandalism technique... I work with kids you know lol]

which is fine but i dont like to think of computers with any sort of wires sticking outside of the case - plus its a bit fiddley and if you forget that the fans are attached to them - i.e. if you need to get to them =- then its gonig to make matters worse when you here a ripping sound

But I digress....

What would be the best way do you think to achieve this? Are there any cheap power supplies [not particularly PC ones of course] that could do this?

Its purely to extract heat due to the temperature inside the cupboard. Due to the particular design of the computers we are using, the fans inside the computers are on the side, as opposed to the front/back. While this isnt usually a problem in most cupboards [a simple drilling of lots of holes in the sides of the cupboards], i can't do this as the cupboards have tambour doors in them [meaning the sides of the cupboards cant be used.

My plan is two large [120mm] case fans at the top / roof of the cupboard extracting air [as there is gaps between the shelfs] the air should be pulled upwards [although there are some holes in the back wall of the cupboard for the cables to go through etc which could very well disrupt this slightly] and I could have large vents [or additional case fans] sucking air into the cupboard near the bottom of the back of the cupboard [not at the very bottom for the obvious reason of drawing in dust - though the room is hoovered each day].

I did wonder whether wiring up a multi adaptor [http://www.argos.co.uk/static/Product/partNumber/9820164.htm] and the case fans would work, as they are only low power devices surely.

Any suggestions would be really welcome - but PLEASE bear in mind that I'm in the UK, so links to US products wouldnt be much use.

Many thanks to those that can help
Nath.

+12 volts DC goes to the yellow wire,ground goes to the black, the amount of current that the fans draw
should be labled on them just add them together and get a 12V DC power supply with a current rating
greater than the amount that the fans draw. Your multi adaptor should work if it is DC and not AC
(I can't tell from the picture) and the fans don't draw over 600ma. Also if you don't have a meter
to figure out which lead from your adapter is positivejust hook it up to a fan and if it runs backwards, reverse the wires.

After looking some more at that adapter it looks like it is an AC adapter. You will need a DC adapter.

that would be pretty cool. ive even thought of using my extra case fans as just normal fans to cool me down in the summer...

I've done something exactly like this. A simple 12V power brick from a dead router, a switch, and a 120mm case fan. It's a pretty easy project, and if you've got the right soldering tools, shouldn't take you more than an hour to complete.

Just cut off the output plug coming from the power brick (the one with 12V on it). Find out which wire is 12V and which is ground using a voltmeter/multimeter. Hook those wires into the switch and then wires coming out of the switch and connect them either directly to the wires coming from the fan, or into a standard molex connector.

If you want to be fancy, you can get a double-throw-double-pole switch and put a resistor in series on the second throw to slow down the fan. You'll have to play around to find the right resistor for the speed that you want, but you'll end up with a fan that has a high, low, and off setting.

Also keep in mind the power dissapation of the resistor. W=I²R. The resistor will be dissapating most of the wattage when the fan is run on low speed, make sure it is rated at a high enough wattage so it doesn't overheat and potentially cause a fire.

This is true... I remember some classmates blowing up various electronics components (MOSFETs in particular) by pumping too much current through them.

"ok... let's try this again..."

*flips switch*
*nothing...*
*BAM!*

"crap..."

Hey.

Thanks for the suggestions guys. I'd prefer one power "brick" to run at least two fans. The case fans i was looking at was the Antec Smart fans that have a temperture sensor in them [will they automatically change speed then I wonder?].

Anyone care to knock up a very very basic diagram? Its been a long time since i've done this sort of work hehe and like you said, i dont want it to catch fire or something :S

Cheers
Nath.

PS. Do you think it would be safer using a molex connection on one of the pc's then? Alot less hassle most likely I would wager but.....

If your not afraid to do a bit of work, you can try and build a MolexHub

MXH for short

Basically its a small PSU about 200w or smaller, in a box, with female molex plugs extruding (but keeping flush) on the box... I'm not home at the moment, but I could whip up a couple of pics to show you what I mean

I use it for my home made media center to power hdds

undead.... I'd be interested in those pics

I think for now though I might have to connect them up to the computers themselves, but I'm still not 100% on where is going to be best to place them *puzzled*

I'll post a pic later if I can showing the cupboard and "one type" of computer that is in them.

Cheers
Nath.