John said:
Yes, as far as I know, any adapter (wall wart) that outputs 12 V DC
will power a 12 V case fan, if you correctly connect it.
This should be able to power a few fans. The fan may have a current
rating on it, and the adapter you choose should have a higher
current rating than the sum of all the fan currents to be run.
12VDC 1500mA AC Adapter $23
http://www.radioshack.com/product/index.jsp?productId=2190632
http://rsk.imageg.net/graphics/uc/rsk/Support/ProductManuals/2731775_PM_EN.pdf
6-inch Adaptaplug male to two tinned wires $3.39 (ouch)
http://www.radioshack.com/product/index.jsp?productId=2049699
That is an example of a fairly compact solution. (You could also
have chopped the end off the adapter, and saved yourself the
$3.39 plug and wire.)
Using an ordinary ATX PSU, connecting PS_ON# to an adjacent COM
pin, is another way to make a power source. Make sure the fans are
connected, and connected correctly, before connecting PS_ON# to COM.
PS_ON# is used for "soft" power control, and will turn on the
12V rail when grounded to COM. The 12V rail is available on one
of the many Molex 1x4 hard drive connectors of the supply. The
ATX supply is bigger and noisier than the Radioshack style
solution, but if you already own it, it is free.
To make fan adapter cables to an ATX supply, you can use
something like this. This particular one can be "daisy-chained",
meaning you can stack these end to end, to handle more than
one fan on the same disk drive power lead. Notice that the
adapter taps into the yellow (+12) and black (ground) Molex wires,
to power the red (+12V) and black (ground) fan wires.
http://www.pccables.com/cgi-bin/orders6.cgi?action=Showitem&partno=07057
http://www.pccables.com/ig.php?image=07057.jpg
If you chop up the previous item, and join the fan connector to
the Radioshack 2049699 cable, that will make it easier to plug
in a fan to that 12VDC 1500mA adapter. Luckily, my local
(good) electronics store, had male and female three pin fan
connectors, so I've been able to make my own adapters when I
need them. But having ones like the pccables example, is pretty
convenient.
So a little soldering, or twisting of wires, might be required,
depending on what you decide to do. I use heatshrink (polyolefin)
tubing to try to cover the bare ends. Sometimes, that stays in place
longer, than electrical tape (gummy). Applying too much heat to the
polyolefin, will burn through it, so you have to experiment with
it first, to see how it works.
http://www.gatorelectronics.com/heatshrink.jpg
In this picture, you can see how much it shrinks when heated.
A mistake I make quite often, is trying to make a "glove"
fit, when a bit of slack really doesn't hurt when selecting
the right size for the job.
http://www.ketolainen.com/images/uploads/ScreenHunter_002.jpg
HTH,
Paul