Fans and the Fan Controller
We’re actually going to start with the fan controller, it has a switch and a knob and two LEDs:
“PWM” means the PWM signal from your motherboard is passed through the unit to the fans (you can use this to split a single motherboard PWM header to run both fans), “VR” means the knob is in control of the situation. Now naturally I can’t leave this thing in one piece, it’ll have to come apart.
Side one, not much to see here. Just the VR and the switch and the headers. The fan power goes through a worryingly small trace, but it didn’t have any issues in testing. I wouldn’t try to use this to power really high power fans though. The back side is more interesting:
There’s a voltage regulator to drop the 12V to 5V (what fans want their PWM signal to be), a NE555 bipolar timer, and some resistors and caps and diodes to make the 555 flipflop. It looks vaguely related to the Overclockers.com DIY PWM fan controller. I’ll go into more detail on the functionality in the testing section.
Then there are the fans:
