An Arduino measures the temperature of the room via a DS18B20 temperature sensor which then has the servo turn the control knob to the appropriate position, on or off.

Control is via an Arduino Nano, with a few push buttons and a 16 x 2 LCD display for user feedback. Often, completing a first build will reveal all manner of limitations and drawbacks of a design.

I used an LCD shield to display the current temperature and speed of the fan, but you can use the circuit without the LCD display. You also need to select the transistor by the type of fan that you ...