Building a Geiger counter and testing different free available radioactive materials

#DIY #geigercounter #radioactive DIY α, β, and γ sensitive Geiger counter I designed and built. The highest activity was shown by an old gas mantle containing thorium dioxide, which at that time was a commonly major component of the incandescent mantle, as it is also called. All the radioactive materials can be bought with no restrictions on eBay. I also show how to convert cpm to µSvh.