A simple PWM-based driver for your Raspberry Pi Fan

This is a DIY project for adding a driver for your Raspberry Pi fan. Using its GPIO pins, some cheap components, a bit of Python code and a custom PCB, the fan can be used at various speeds depending on temperature instead of having 2 different speeds changing between 3.3 and 5V pins. In addition, it is beginner-friendly enough so that anyone can make this easily in a short amount of time.

Just a little bunch of things:

• A PN2222A (or similar transistor)
• A common diode that supports at least 5V and around 300-500 mA
• 1K resistor
• A bunch of jumper wires (or solder any wire to the RPi and/or PCB)
• Soldering iron
• The PCB in this repo (I ordered it at JLCPCB)

• First of all, I recommend trying this build on a breadboard (see this link for extra information about building this on a breadboard)
• Once inserted all components properly on breadboard download the code from this repo with git clone https://github.com/Pelochus/RPi-Fan-Driver.git or download directly from Releases tab in github.com
• Edit both minspeed-calibration.py and rpi-fan-driver.py with your preferred GPIO pin (Note: BCM numbering is used)
• Optional: Run minspeed-calibration.py and insert values until you find your minimum speed for your fan (should be around 20-40%, default is 50%). Note: Needs rpi.gpio library already installed
• Optional: change tempSteps and speedSteps in rpi-fan-driver.py
• Now run install.sh as root sudo ./install.sh. This will only work with distros that use apt (Debian-based) and have bash (pretty much every distro). If you don't have apt you can manually install rpi.gpio Python library manually
• Reboot
• Make sure is working properly. Try to run any heavy task on the CPU, like a benchmark. The fan should start spinning at a certain temperature (default 45ºC) and keep increasing linearlly according to temperature changes
• Now, if everything works properly, order your PCB
• Solder all the components to the PCB (diode, transistor and resistor)
• Finally connect the wires to their corresponding pins in your RPi and holes in PCB. Even though I soldered the wires to the RPi, I suggest using as much as possible jumper wires
• Put the PCB in a safe place without making contact to the RPi board (Warning: If your PCB makes any contact with your RPi motherboard, something bad will happen, probably you will end up with a fried PCB and/or RPi)
• Optional: Print the .stl in this repo to protect lower part of the PCB (useful for previous step)
• Put the build inside your RPi case similarly to my build (see images below)
• Done!

This Instructables article for providing me the electronics diagram and code to make this