Materials

• Geiger Kit - GK-Mini
• SBM-20 Geiger counter Tube
• plastic box for case
• battery holder, batteries
• power switch

The GK-Mini kit

In the kit:

The kit comes in these 3 major parts - display module, IR keypad that will be used for navigating the setup menu once the device is assembled, and a bag of small parts. You will need to add the geiger counter tube, case, power supply, and power switch.

In the bags:

The parts are further divided into several small bags. One bag contains 9 10Mohm resistors that help with measuring the high voltage (usually not needed). The high voltage adjustment potentiometer comes pre-adjusted for 450V that should work for most tubes, the Arduino board also comes preprogrammed firmware.

Build instructions are clear and easy to follow, this is a one evening project. The only adjustment needed after assembly is setting the display contrast using a trimpot.

Assembled:

The assembled unit is nice and compact 3 layer stack:

It consists of main PCB with LCD mounted on standoffs on top of it, and arduino board sandwitched between the two. For accessing screw terminals for power supply and geiger tube attachment you need to remove the LCD board.

The meter worked right away, I hooked up a SBM-20 tube to it and was able to make the count go up a little by putting smoke detector on top of the tube.