Raspberry Pi Fan Control

This project provides examples of fan control based on the current CPU temperature.

It includes implementations of a relay controller and a proportional controller.

The fan is connected via a transistor switch to the 4th pin of the I/O ports. The fan connection pin can be changed in scripts. The remaining parameters can be set at startup.

🚀 Quick start

Prerequisites

Clone repository:

git clone https://github.com/Nkeramov/rpi_fan_control.git

Switch to repo directory:

cd rpi_fan_control

Traditional method with venv and pip

Create and activate virtual environment:

python -m venv .venv 
source .venv/bin/activate       # Linux/Mac
# or
./venv/Scripts/activate         # Windows

Install dependencies:

pip install -r requirements.txt

Run relay fan controller with command (args for example):

python3 relay_controller.py --lower 45 --upper 50 --delay 5

Run proportional fan controller with command (args for example):

python3 proportional_controller.py --temp 45 --delay 5 --p 15.0 --dmin 50 --dmax 100

Modern method with uv

Install dependencies and create virtual environment automatically:

uv sync

Run relay fan controller with command (virtual environment is handled automatically, args for example):

uv run relay_controller.py --lower 45 --upper 50 --delay 5

Run proportional fan controller with command (virtual environment is handled automatically, args for example):

uv run proportional_controller.py --temp 45 --delay 5 --p 15.0 --dmin 50 --dmax 100

Or with explicit activation:

source .venv/bin/activate       # After uv sync
python3 relay_controller.py --lower 45 --upper 50 --delay 5
# or
python3 proportional_controller.py --temp 45 --delay 5 --p 15.0 --dmin 50 --dmax 100

Also you can use the launch script run.sh, making it executable first

chmod +x run.sh

The script arguments can be changed as desired.

🔌 Connection diagram

The connection diagram is shown below. The fan is controlled by a transistor switch based on the IRLML2402 N-channel MOSFET.

In my case, I used a 12-volt fan instead of a 5-volt one, because experiments showed that the 5-volt fan was noticeably noisy even at minimum speed. The fan cools the radiator down to an acceptable 45 °C pretty quickly. The photo also shows how the fan and transistor switch are connected to the board.

⚙️ Adding to startup

You can set up automatic script launch at system startup.

Open the /etc/rc.local file in editor:

sudo nano /etc/rc.local

Add to the end of file this line:

/home/pi/raspberry_pi_fan_control/run.sh &

Press Ctrl+O → Enter → Ctrl+X to save and exit. With these few easy steps, you now have automatic fan control.

🤝 Contributing

If you want to contribute, please follow these steps:

1. Fork the repository.
2. Create a new branch for your feature or bug fix.
3. Make your changes and commit them.
4. Push to your fork and create a pull request.

📝 License

This project is licensed under the MIT License. See the LICENSE file for details.

📚 References

• Getting started
• Raspberry Pi OS
• RPi.GPIO