Introducing OpenRad, a simple radiation monitoring solution powered by the SBM-20 GM tube and TTGO ESP32 microcontroller. this project offers a user-friendly approach to tracking and measuring radiation levels.

With OpenRad, you can build your own dosimeter without complexity. The SBM-20 GM tube detects ionizing radiation while the TTGO ESP32 gathers and transmits data to its built-in website.

Additionally, MQTT helps with seamless communication between the device and any other device. allowing for easy integration with other systems and applications.

The code and design files are all available at the GitHub Repository.

So, let’s dive straight in.


Theory of Operation: 

Geiger-Muller tubes are devices that detect radiation by using a gas-filled chamber with an electrode inside. When radiation enters the chamber, it ionizes the gas, creating a detectable electrical pulse. The SBM-20 tube is a type of Geiger-Muller tube that is sensitive to beta and gamma radiation. It requires a stable high voltage (around 400 volts) to operate.

To generate the high voltage needed, a boost converter circuit is used. This circuit steps up the input voltage to a higher output voltage using a PWM signal from a microcontroller. The boost converter operates based on a fixed duty cycle, where the ON and OFF times of a switching transistor control the voltage output.

When a high-energy particle hits the GM tube, it ionizes the gas, creating a pulse that can be detected by a transistor amplifier. This amplifier sends an interrupt signal to the microcontroller, indicating the detection of radiation.


Key components include:

PCB Design:


OpenRad's software architecture has several components, each serving a purpose and contributing to the device's functionality.

The software can be grouped into two categories:

Embedded Software:

Web Interface:


OpenRad came about because we wanted to make radiation monitoring simpler. And we shared it because we thought, maybe Somone will find it useful.

We're excited to share our project with everyone and hope it inspires others to get creative.

Again, a big thanks to PCBWay for their support in making this happen!

What should we do next?


GitHub Repository