Sparkfun has some very cool products to experiment with. I ordered a class 5 Geiger counter, SAMD21 and I just verified it with a calibrated Cesium 137 source and it is spot on. Calc. 1866.20 CPM reading avg of three 2min 1866.66 CPM @sparkfun #electronics #radiation github.com/thedocdoc/Pock…