I know that MOSFET can be used as a switch. When sufficient Vgs is applied, MOSFET will turn on and so the load (fan).
This is my understanding of this circuit, please correct me if I’m wrong or missed anything?
5V PWM is a digital signal and by adjusting the duty cycle, I can control the average value.
For 100% duty cycle Average voltage = 5V For 50% duty cycle Average voltage = 2.5V For 0% duty cycle Average voltage = 0V
So if I apply a 5V PWM with 50% duty cycle to the gate of MOSFET it will turn the MOSET On and OFF depending upon the Ton and Toff value(Ton= Toff since duty cycle is 50%). Since this ON and OFF happen so fast, if I check the output voltage using a muti-meter it will read 6V (50% of 12V), and in a CRO or DSO I can see the 12 V PWM. Therefore, the fan will operate at 6V and will run at half the speed (if the rated speed is 500RPM, it’ll run at 250RPM).
I tried to explain with a picture also
I'm not an electronics guy so I'm expecting simple answers