What is it?

The Open Source Ionizing Radiation Indication System can be used as a standalone geiger counter or dosimeter and as a data logger or true random number generator when connected to a PC via USB. It uses widely available components and is optimized for low power consumption, making it well suited for portable operation.

Why did you make it?

As someone with a curiosity for radiation, I was looking for an open source geiger counter a few years ago, that was affordable, used only easy-to-source components, was energy efficient enough to be portable with a decent runtime and somewhat close to commercial products in features and build quality. When I was not able to find such a device, I decided to design one myself and after many hours of hard work, this is the result.

Documentation

The source code, schematics and documentation are availabe on GitHub

The STL files for the enclosure are available on Thingiverse

Features

• low power design (~1mA at background levels)
• supplied by a single cell LiPo battery
• charging of battery via USB port
• uses the proven SBM-20 G-M tube
• high efficiency 400V power supply
• precision pulse amplifier
• clicker can be switched on/off
• easily readable 16x2 LCD
• multiple display modes
• automatic calculation of dose rate
• selectable dose rate low pass filter
• dead-time compensation
• adjustable dose rate alarm level
• alarm can be muted
• display of total accumulated dose
• adjustable internal clock
• internal voltage readout
• keypad lock
• power on self test
• firmware can be updated via USB
• serial command interface
• dose rate logging on virtual serial port

BYOB - bring your own battery

I currently don't have a simple way of legally sending a lithium battery with the kit :( You can connect any single cell with a JST PH connector and a capacity of at least 300mAh, a 104050 cell fits the enclosure nicely.

Disclaimer

This device is not a finished product, it is not intended for household use but only as an experimental development kit for use by qualified professionals in a laboratory setting and should not be considered a scientific instrument or safety equipment.

Warnings

• The linear charger is set to a current of 300mA, the connected battery therefore needs to have a capacity of at least 300mAh for a safe charging rate of 1C.
• Do not attempt to charge non-rechargable batteries.
• Don't let the battery charge unattended.
• Don't touch the PCB while the device is powered on, high voltage is present.
• The high voltage capacitors stay charged for a while after powering off the device.