This radiation detector clicks, flashes, logs radioactivity levels, and shares its data with the world.

By John Iovine

I’ve been designing, making, and selling Geiger counters for 15 years through my company, Images Scientific Instruments. They’re fundamentally simple devices; you just need voltage high enough to run the Geiger-Müller (GM) tube. Anyone can design a counter that will work somewhat, but it’s hard to make one that’s reliable and long-lasting, because the electronics are so touchy.

Last year I was redesigning my basic Geiger counter circuit when the earthquake, tsunami, and nuclear crisis hit Japan. We sold out immediately, ...

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