I attended the second DIY geiger counter workshop on August 22. This was taught by Kalin, and involved soldering three parts of a homemade gieger counter:
- Freakduino motherboard (right) - this is basically an arduino board with a wireless radio interface. It provides the power to the NetRAD and keeps track of the rate of radioactive events.
- NetRAD shield (left) - an interface to power the tube and keep a TCP/IP connection for communication.
- SBM-20 Geiger-Muller tube (middle) - this is the tube that receives the radioactivity to measure.
The soldering for the first two was through-hole attachment of various components like dipswitches, header pins and a small breakout board. I messed up a couple of things but got help to fix them. After soldering, we tested by connecting power (USB 5v) and seeing if the LEDs turned on.
The soldering for the GM tube was attaching wires to some clamps that were put on each end of the tube.
Once the soldering and assembly was complete, connecting USB and Ethernet gives a powered interface. The NetRAD uses DHCP to request an IP address over the network, and a short configuration later the counter was set up to record radioactivity to the online feed manager pachube.
I bought a 100 yen food container to place the boards and tube in, and connected them at home. The ethernet jack was connected to my wireless router, and the USB (for power) cable was also connected to the USB port I have on the router.
My feed can be found at https://pachube.com/feeds/34604 It's set up as part of the tokyohackerspace user's feeds. The two graphs it gives are in counts per minute, and a conversion to microSeiverts/hour.
Apparently this counter is not calibrated, so it will not give a trustworthy measurement in uSv/hr, but if measured over a length of time it should give some warning about spikes or decreases in background radiation.