Monitor for radioactive radiation based on STS-6 (CTC-6) Geiger tube. Sensitive to gamma and hard beta. Transmission every 60 seconds. Dose rate is estimated from pulse rate with fixed factor. Normal level is just below 0.1 µS/h.

10 Wp solar panel, two 3400 mAh Li-CoO2 18650 batteries in parallel, permanent small ~50 mW load. A shunt regulator limits battery voltage to 4.1 V. An externally powered ESP32 measures sol and bat powers for ThingSpeak.