An article presenting a simple DIY Geiger Muller counter using the Russian tube SI-22G and a single transistor regulated inverter that puts out 400V, as required by the tube. A very basic detector assembled in 5 minutes. See an operation comparison to the Radex RD1706.
A short review on the Radex RD1706 dosimeter, how good it is, and how can it be compared to other dosimeters, eg. the Terra-P MKS-05.