[werk_ag]

Hi Loris

The Led's and the diode are correct. At first look they seems reversed but they are not. The MosFET's drives the GND line.
The diode is only a protection just in case someone use the fan as a wind mill.

Any variable resistor greater than 10K will be fine for R8. Even a fixed 10K 1% resistor will do the job, but you loose the possibility to fine adjust your wind vane. Usually this procedure is not necessary, the variable resistor is there, just in case...