This is one of the smallest fan controllers I’ve seen. It does the same job as others, it controls the fan speed according to a temperature sensor. The main utility is that you save power this way, and second its noise reduction, the fan will now run most of the time at lower speeds. The whole circuit its based on 3 parts:
- A MOSFET Power transistor (N-Channel), price between $1 and $2
- A 10K spindle trimming potentiometer, price around $1
- A 10K NTC temperature sensor, price around $1
These are really easy to get parts, so you wont have any trouble. As a last word this is a very useful and simple to build project. Good luck building it.
Fan Temperature Controller: [Link]