PWN Fan controller with temp sensing and button override

I needed a fan for my server room and my garage. Normal wall exhaust fans are quite weak (need high static pressure) unless you go for the big duct fans but had no space.

So I got a Noctua PPC 3000 PWM and needed a way for it to reduce it's speed when needed as it's quite loud and it does not always have to run at max speed.

Looked for a PWM controller with temperature based control but could not find anything decently priced and that I could power with the same power supply without a voltage regulator.

I found the following project https://create.arduino.cc/projecthub/tylerpeppy/25-khz-4-pin-pwm-fan-control-with-arduino-uno-3005a1 and used it as a base to create my PWM controller.

I used the Arduino Nano since it's a lot smaller, can accept 12v on the VIN pin (I guess most Arduino's do) so that I can use the same power supply for the Arduino and the fan without using an external voltage regulator.

Also been thinking of using the z-wave enabled Arduino nano clone and integrate it with home assistant but another time.

For the garage I need to be able to override the temperature based control thus added a button, it's not necessary and can be removed altogether.

Then you can just 3d print a case with a hole for mounting and screw it to the fan or build a case around it.

Note that this is a quick and dirty project and some refinements can definitely be made!