This regulator uses a P-FET to change the positive supply voltage to a FAN
an NTC resistor mounted on the device that needs cooling will change the fan speed,
the temperature on the heat sink will therefore be constant, while the FAN speed will change, depending on power disipated
The RPM output signal from most FAN types will continue to function, due to the positve voltage regulation.
There is many other ways to do this, but since I have fine access to P-FETS and they have super hight gain, a perfect solution!
The Fan regulator schematic, the gate capasitors filter the NTC voltage so regulation is nice smooth,
The output capasitor remove FAN noise when it is running on low voltage, the FAN draw it’s current in pulses so without this cap it will noise.
If you have a 10K NTC you use a 10-22K trimmer, if you have a 22K NTC use 22-47K trimmer, 47K NTC use 47-100K trimmer and so on.
Copyright Thomas Scherrer