Arduino - PimpMyGeiger
whyA couple of years ago I bought a Geiger counter from Sparkfun:
It works pretty well albeit somewhat boring; a blinking light and an ascii character via its serial port.
first versionThen one day I had an idea: I should make it visually more attractive. I had tons of led-matrixes laying around (they cost almost zero china dollars) so I soldered an arduino to the signal-pin of the geiger counter and created a "sketch" that switches a led on or off depending on if it saw a pulse in the current second. Others may have a different view but I find the result dramatically interesting; this is movie material!
oopsDuring the development I accidently found out that the sparkfun geiger counter has an arduino bootloader so I've uploaded that sketch to the geiger counter as well. It then does not work anymore. Could not get the hex-file with its original firmware to upload so I figured out how it works and re-implemented (download link) its firmware in an arduino sketch.
second versionThen one day a guy from our local hackerspace showed a geiger counter he bought from aliexpres.com:
Since it costs 75% less than the sparkfun counter and since I wanted another one to walk around with (to scare collegues), I decided to buy that one. It can be powered from a couple of different connections (usb, a jack plug, via pins) and uses almost no watts. It has a convenient set of pins to send a pulse to an MCU and it has a jumper to disable the speaker that produces a sound for every particle detected. I soldered a switch to that jumper, then added my arduino and a led-matrix to it and a nice blue led that toggles for each particle. A couple of minutes click around in inkscape and a nice wooden box appeared from the lasercutter (with lots of hot glue, of course).
third versionWhen the second version was finished, it sat on my desk at work for a while. I realised that some essential features were missing. I wanted to know how many particles were detected in the last second (the first and second version would only light up one led for 1 upto infinite particles).. I wanted to know how many in the last minute and also in the last hour. So more leds, more displays and lots of more hot glue was required! In the 7-segment display, on the left you see the count per hour and the 3 digits on the right show the count per minute. The led-bar shows the count in the last second.
Below it you see a relatively cheap 1800mAh battery pack I bought. This whole new wooden box uses less than 0.1A so if I did my maths correctly it can run for at leas half a day on it. Enough to investigate the neighbourhood for radiactive material enthousiasts!
The source-code of this version is in this zip-file.
Please note: the screw-holes to mount the geigercounter are a bit off; in length they should be +/- 3mm closer.
fourth version?Who knows! I'm considering a version with a WAV-shield that plays different sounds depending on the energy of the particle etc. No idea how to measure that yet.