I have a big box of scrapped GOOD computer fans, pulled from old servers and workstations I collected over the years. MOST ALL of them are 3-wire, red-yellow-black, and labeled "BRUSHLESS 12V" on the stickers. Normally for something so simple, I hook up red & black DC voltage and MAYBE a SWITCH, then be DONE with this - but unfortunately, it's not the case with these complicated BRUSHLESS motor fans.
I tried to scan around eBay for a driver board, something I could use - but got lost, and it keeps kicking back drivers for R/C copters, cars and whatever else. I do not want to buy a $15 ESC, then PWM it with an arduino just so I can re-use these simple NICE fans.
Does anyone here know WHAT I need to search for or have a link or something to help me please? I just want to buy a little cheap circuit board to drive these fans, I am sure they must exist somewhere but I am struggling to find them.
There is nothing complicated with these fans at all. Just connect the power to the red and black - they are polarity sensitive - and go. The Yellow is only the tacho readout
Ok thanks. I did try hooking up the power, but the one or two I tested seemed to spin too slow- but I'm sure it's probably jammed inside with dust. Thank you.
Those are 12v fans with tach output. If you dont need the tach, Connect positive side to +12v negative side to drain of n channel logic level mosfet, source of said fet ground and gate to arduino pin via 100 ohm resistor, and 10k between gate and gnd.
If you do need tach output, you can't switch the low side safely or else the tach output will rise to 12v.... so need to switch the high end. So negative to gnd, positive to drain of p-channel fet source of that fet to +12v, gate with 10k (maybe 1k is better if pwming) to drain and to the drain of an n channel logic level signal (ie, rated for low current) mosfet; of that fet, source to ground, gate to arduino pin via 100 ohm resistor and 10k pulldown to ground. And tach output to arduino input pin, via say 4.7k resistor for safety, it might need to be input_pullup.....
Either way nothing fancy needed to drive it - at most the usual pair of fets for driving high side of something
This is literally the first Google result when I search: How PC Fans Work
If a 3-wire fan doesn't work with 12V power then it's borken. Hooking up random wires until it works isn't likely to damage it.
A 4-wire fan which is expecting a PWM input on the 4th wire can be run at full speed by leaving that unconnected. So it also works with plain 12V power.
Brushed or brushless will both spin without power (unless the bearings are siezed) so that's not how you tell them apart.