NoteBook Fan Control (NBFC) - Cross-platform solution for laptop fan control, written in C# and works under Mono runtime.

Most suitable for desktops and laptops, where fan controls are available via sysfs(5).

Fancontrol (lm-sensors) - Script (written in Bash) to configure fan speeds.

There are multiple working solutions for fan control for both desktops and notebooks. Here is some more information about this topic. In some cases, you will not be able to use the Fancontrol script due to incompatible cooling architecture (e.g. Some laptops have two fans for CPU and GPU, but the first fan cools down CPU and GPU at the same time, while the other one cools CPU only. Some laptops have single fan for both CPU and GPU and cools both at the same time. Note: Laptop users should be aware about how cooling system works in their hardware.

9.2.2 Alternative solution: absolute paths.

9.2 Device paths have changed in /etc/fancontrol.

9.1 Increase the fan divisor for sensors.

7.5 Fan control modes on certain TUF series laptops.

7.3 Alternative method using EC registers.

7.2 Generate configuration file with pwmconfig.

2.4 Fancontrol stops working after suspend–wake cycles.

What I do with my board is applying a 3rd order active low-pass RC filter with quite high R's so small capacitors can be used (and no inductors), and a transistor as a current buffer, so there is not transient at all and the frequency can be as low as the Duex 5 is without problems. But for 250Hz L-C should be huge as hell for it to work.

The resonant transient depends on the L-C values, and in a lesser way on the real impendance of the exact fan you are driving. Ouch! Not only the LC filter is too small for that frequency, but it also transients over 18V on each cycle. Now, lets try with a lower frequency, like the one Duex 5 forces on PWM fans (250Hz, IIRC), 50% PWM again: I don't think it would be a problem for a fan, but for other kind of loads, it may be.

Now the transient gets to 18V, but it also stabilizes fast. There's some overshoot, but the voltage stabilizes fast, and only a small hint of the PWM frequency remains. This is the simulation at 50% PWM, 65KHz: The part on the right is the fan (modeled as a pure resistor load sinking about 170mA at 12V), with the capacitor in parallel and the inductor in series with Fan. This should be the simple LC filter schematic: I'm sorry I ran out of time yesterday night.

12 volt dc fancontrol