Flexible Radiation Monitoring System Speaks LoRa And WiFi

A black PCB with an ESP32 and an SBM-20 geiger counter

Radioactivity has always been a fascinating phenomenon for anyone interested in physics, and as a result we’ve featured many radioactivity-related projects on these pages over the years. More recently however, fears of nuclear disaster have prompted many hackers to look into environmental radiation monitoring. [Malte] was one of those looking to upgrade the radiation monitor on his weather station, but found the options for wireless geiger counters a bit limited.

So he decided to build himself his own Wifi and LoRa compatible environmental radiation monitor. Like most such projects it’s based on the ubiquitous Soviet-made SBM-20 GM tube, although the design also supports the Chinese J305βγ model. In either case, the tube’s operating voltage is generated by a discrete-transistor based oscillator which boosts the board’s 5 V supply to around 400 V with the help of an inductor and a voltage multiplier.

Graphs showing temperature, humidity and radiation levels
Data can be visualized in graphs, together with other data from the weather station like temperature and humidity

The tube’s output signal is converted into clean digital pulses to be counted by either an ESP32 or a Moteino R6, depending on the choice of wireless protocol. The ESP can make its data available through a web interface using its WiFi interface, while the Moteino can communicate through LoRa and sends out its data using MQTT. The resulting data is a counts-per-minute value which can be converted into an equivalent dose in Sievert using a simple conversion formula.

All design files are available on [Malte]’s website, including a PCB layout that neatly fits inside standard waterproof enclosures. Getting more radiation monitors out in the field can only be a good thing, as we found out when we tried to detect a radiation accident using community-sourced data back in 2019. Don’t like WiFi or LoRa? There’s plenty of other ways to connect your GM tubes to the internet.

12 thoughts on “Flexible Radiation Monitoring System Speaks LoRa And WiFi

    1. The SBM-20 is a vintage soviet product, they are no longer in production. The Soviet Union at that time included Ukraine of course, so the SBM-20 is as much “Russian” as it is “Ukrainian”.

      I ordered one of the GGreg20_V3 GM devices from Kyiv, delivery to Gerrmany was faster than many shipments from the USA. Very pleased with the device and I ordered two more. They also sell solo SBM-20s.

    1. Cool! This is an idea that lies on the surface. All radio amateurs, for a reason I do not understand, make complex and beautiful weather stations that include only the BME280, which allows you to measure temperature, atmospheric pressure and relative humidity. At the same time, forget about such environmental parameters as background radiation or ultraviolet level. I have already given as an example the GGreg20_V3 module, which is excellent for both stationary and pocket-sized DIY / IoT devices for measuring radiation indoor and outdoor and btw is supported by majority of MCUs and Dev. environments.

  1. If you want early-warning detection of something like a reactor accident, you’d probably want to detect alpha emitters instead, and this would require a mica window tube. The metal-wall tube shown only detects gamma emitters. It makes a good random number generator, I guess.

    1. To check these devices, you may (1) measure background ionizing radiation level. But, if you want to calibrate your own, also you can (2) do this against another trusted and certified device. And at last, of course (3) well calibrated radiation source may be used.

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