So the 3.3V PWM signal from ESP is sent through R2 to the Gate to breakthourgh the Vgs(th) to make Mosfet ON, and the author of the circuit say Gate is pulled high to 12V by R1. But I don't understand how exactly work. How to calculate for Vgs, is it 3.3V or 12V when it is ON,and why? If when Mosfet is ON, is Vgs the combined of V from +Vo 12V and ESP 3.3V? If the #16 is 0V,which there'll be a flow from 12V to #16, is there supposed to be a Voltage between R1 and R2, why is MOSFET is OFF?