Extruder fan controller on a Sanguinololu?

I'm trying to setup my mendel kit to print PLA and want to have a fan for the PEEK tube of the extruder to prevent the filament from getting too hot before hitting the nozzle and causing problems. I can get a fan and attach it to the side/bottom of the extruder base, but what is the best way to control the fan speed?

I know with RAMPs and other electronis setups there are fan controllers, but I have the Sanguinololu setup and looking at the main page (http://reprap.org/wiki/Sanguinololu) I see no way to wire up a fan. Should I just wire it up full all the time or is there some fan controller outputs that aren't mentioned on that page?

Thanks,
Bret

Try here - Nophead's fan hack

I fitted a Zalman Fan Controller to my Mendel90 and use it to manually control the speed of the part cooling fan.
I had to do this because I have an LCD and Click controller attached to my Sanguinololu so I didn't have any spare pins left.
It cost very little and works very well.

i just use the 12v and run my fan all the time. i've out a header on it so i can plug and unplug it when not needed.
works fine.

Thanks for all the ideas. The fan hack looks interesting, but sounds pretty complicated with all the firmware issues and such. The fan controller looks promising but I'll probably start by just directly wiring it.

I have a fan that I swiped from a small heat sink but I don't know if it's 5V or 12V and I can't find anything on it that indicates. Any ideas on how I can tell short of just plugging it in and seeing if it flies away or burns up :-)?

Thanks,
Bret

if you still have the product that i came from, you can just measure the voltage it puts on the fan.
if not, take a 9v battery and hold it on there. if it turn to fast and starts vibrating it's probably 5v
if it spins, but just bot top speed it should be 12v.
i got mine out a old laptop, and that was 12v. (said the sticker)

Thanks Possenier. I don't have the original product it was just in a pile of scrap. I like the idea of starting with 9V and seeing how it operates. Thanks for the idea.
-Bret

With a mechanical end stop I have been planning to wire up my z end stop in the normally open configuration and wire up the fan in the normally closed configuration to the same switch. When at z=0 the fan will switch off, but for all other layers it will turn on.

That's a good idea. So when the print head is home or on the very first layer the fan will be off. Otherwise it will run. Nice. I may have to copy your nice idea.
Thanks for sharing,
Bret