Geiger counters are used to detect radioactive emissions like beta particles and gamma rays. While it’s more than likely you never encounter these detectors in your daily life (unless you’re Bruce Banner), a device like this is incredibly useful when working with any kind of nuclear experiments.
Of course having a Geiger counter makes for a great conversation piece, and following the Fukushima disaster some people just want to see for themselves if there are any radiation sources in the area. This DIY Geiger counter kit from MightyOhm offers a fully functional tool for a fraction of the cost associated with commercial options.
The finished Geiger counter is powered by two AAA batteries and detects both beta and gamma radiation. It also supports data logging with a USB-serial cable. The entire kit is open-source as well.
In the kit, you will find a PCB with all the electronic components, an SBM-20 Geiger-Muller beta/gamma tube, a clear acrylic case, and mounting hardware. The LED and piezo speaker alert you to detections, while a mute button allows for silent operation if you prefer.
The device supports multiple Geiger-Muller tubes and is adjustable between 300-600V. Headers are included for serial, in-circuit programming of the AVR microcontroller, and pulse output, so you can connect the Geiger counter to other devices.
The ATtiny2313 microcontroller at the center of it all is also very hackable, which offers you the chance to let your creativity run wild with this open source hardware. A link to download assembly instructions can be found here.