So I messed up, I realized this after I was done with the lapse but this was my orignal plan, I was going to use a potentiometer to adjust the speed but there were several severe flaws in my work for some reason I completely dropped the mosfet plan(I dont’t know why I did any of this my brain is on a weird autopilot that isnt smart).
microcontrollers can’t even drive this fan because they only have 3.3v and 5v as options and the 120mm computer fan runs at 12v, which if I continued with my orignal idea would most definitely blow up everything, and the microcontroller can’t even read rpm,

Now I’m going to try this again except this time try and use a little bit of my brain. My new plan is much simpler I’m going to use an esp32, L289N motorr driver which can take the 12v dc power supply,