View Full Version : RPM sensor on fan
silverphoenix
11-14-2007, 11:01 AM
How does the RPM readout line work? its a single wire so I'm guessing it sends out a simple pulse signal that represents the RPMs? I want to make some sort of custom RPM readout that would be awesome.
Calmatory
11-15-2007, 10:52 AM
I believe it sends a pulse on every revolution of the fan.
If you attach another fan to the RPM sensor, you can make both of them to work quite well. Both fans will slow down if you slow down the "master" fan.
Most of the present computer-dedicated fans send 2 (in some cases 4) pulses for each full revolution. You can use any cheap microcontrollers to count amount of pulses, and using timer measure actual frequency. And then just convert it to RPMs/sec and RPMs/min. It's one-two/day job :)
results can be like this:
http://tin.topmods.net/rpms.jpg