USING COMPUTER FANS AS GENERATORS

[CG]

In Hugh Piggot's book, Windpower Workshop, he states that brushless DC motors are just about perfect for use as generators on wind turbines. On discovering that computer fans were powered by these motors I put one on a vacuum cleaner and drew air through it, but I got no current registered with a volt meter. Now I know very little about electics and the more I read the less I understand, so could any of you help me by answering the following questions:

A) Can a computer fan be used to generate electricity?

B) If it can, will it be DC or AC?

C) If not, could computer fans be adapted for use as generators, by removing the M.O.S.F.E.T.s (which I believe change AC to DC) or other components?

I have put these questions to people who are more up on this subject but have not recieve a definative reply from anyone.

Your comments would be much appreciated.

[hiker]

i went to a hobby site--they tear apart cd motors and rewire the stators

with thicker wire...turns them into real screamin plane motors..

i don"t belive a fan motor would be worthwhile--to small....

just my opinon.............

[drdongle]

You have to remove all of the electronics from the fan and the output will be AC.

Carpe Vigor

Dr.D

[RatOmeter]

Unless you're an electronics geek who may have an application for micro... on second thought, pico or femto power, don't bother.  Those fans have integrated drive electronics (hell, some of them even implement the windings as copper traces on the PCB) which are designed to drive it as a motor.  The short story is that these motors would need modification to bypass the drive electronics and get an AC output in regen mode.

Unless you have a known need for 2-20 milliwatts of power or simply wish to pursue it for the educational value or the sheer perversity of it, don't bother.

[test lab guy]

Here is an anemometer setup using a computer fan.

http://www.fieldlines.com/comments/2004/12/1/223128/557/4#4

[DBGenerator]

Computer fans are very smooth and quiet and have very effecient blades.  However as mentioned above, they are wired as motors and have circuits in them so that they cannot be used as generators as they are.  They are difficult to take apart without breaking them.  For the fun of it, I was able to take one apart after destroying about 4 of them and removed the diodes and other electronics.  I was able to spin it by hand and get a reading on a volt meter directly from the coils and dimmly light an LED.  It wasn't good for much other than to see if I could do it!

[CG]

Thanks for your advice. Apart from testing Hugh Piggott's statement about brushless dc motorts there is another reason for me taking a keen interest in computer fans. I am interested in generating small quataties of electricity, less that 100watts, say, and if you take a took at my posting on what I call PTTs (Pneumatic Transmission Turbines) you will see where I'm heading. Computer fans would have made great little power packs (single or grouped)if used in this type of wind turbine. I'm afraid the contributors to that posting completely lost the plot, so it went off on a tangent and never got back on track.

The fans might have also been able to be used in thermal solar projects. I have to say I'm a bit down not being able to use them. Perhaps the companies that make them could be convinced to adapt their fans for generation, they would not earn much money from this but they might get a pat on the back from the green lobby.