With this simple script you can control the speed of a fan according to the cpu temperature of your Raspberry. By default I use pin 13 (BCM), the fan will start to turn on when the Raspberry is at 25 ° C to reach the maximum speed when the temperature rises to 65 ° C. The fan I used is that of an old 12V PC fan, follow the circuit below for the connections
Note: To use the program you must have installed the pigpio daemon. To install it type sudo apt install pigpiod. The script will automatically start the daemon at every startup.
Place the temp.py script on your raspberry desktop, move the fan.service file to /etc/systemd/system/ and give the command sudo systemctl daemon-reload.
To start the newly installed service, type: sudo systemctl start fan, to stop it instead type sudo systemctl stop fan.
You can also start it automatically at boot by typing sudo systemctl enable fan, You can also stop it at boot type or sudo systemctl disable fan to disable it.