IoT Geiger counter

Geiger counters are used for measuring the ionization radiation such as nuclear pollution. The counter is based on Geiger-Muller Tube which is commonly used for counting the ionization radiation. In addition, temperature, humidity and air-quality sensors has been added on the board. The u-blox NINA-W106 OpenCpu module is used for acquiring the data from the sensors and publishing the information to MQTT broker.

Block-diagram
Block diagram

The J305 GM Tube has been used in the project. The tube is operating in 380V to 450V voltage range and the specified sensitivity is 0.1 MeV. A high voltage boost power supply generates the required supply voltage from the 5V DC board input voltage. A PWM signal – which is generated by the host CPU – controls the output voltage driving the GM Tube.

Basic board components

An AM2302 sensor is also used for measuring the temperature and the humidity on the board location. The sensor has 1-wire serial interface and data are polled every minute from the host.

Board schematic diagram

As air-quality/particle matter sensor we are using the Plantower PMS7003 sensor, capable to measure ultra-fine particles of size as low as 0.3um. Microscopic particles can produced by either naturally or by humans’ activities and are affecting human health. The sensor measures the number of particles per m2 of air and clarified the results based on particle diameter (like 0.3to1um, 1to2.5um and 2.5to10um).

PM sensor plugged on bottom side

Starting the board the NINA-W106 is working as WiFi access point, providing a web based management interface for configuring the system parameter. The user can select to configure the counter working either as WiFi access-point or as station providing the desired parameters. Also additional configuration options like MQTT broker parameters, peripherals status, user credentials are available.

Following an example of MQTT message contents published to home/geiger topic:

home/geiger {
    "counter":"24",
    "temperature":"27.30",
    "humidity":"46.50",
    "pm1":"507",
    "pm2_5":"507",
    "pm10":"508"
}
Data published to MagicMirror using MQTT messages

HW design files and software sources are available in the following repository:

IoT Geiger counter
https://github.com/johnkok/iot_geiger
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