You probably don’t need a Geiger Counter but wouldn’t it be fun to have one? This DIY Geiger Counter project will not only demonstrate how to build one, this circuit will also connect to a computer using USB to grab the data. Since this device used very high voltage the output to the USB is opto-isolated to protect the delicate low voltage computer circuitry.

"The Geiger-Muller tube is a simple device, it’s a tube filled with a gas with two electrodes. A high potential is applied betweens electrodes. When a ionizing particle arrived, it create a temporary conductive path between electrodes. The resulting current can be detected by an electronic amplifier. A Geiger counter is composed of a high voltage generator, a geiger tube, an amplifier and a monostable. The following schematic show clearly these 4 parts. In the second part of this article will show how to connect this counter to a USB microcontroler and a computer. "

Thanks Sylvain