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New Feature – Geiger Counter

Here’s something new, an internet connected Geiger counter! The graph in the sidebar is updated once every 60 seconds, and can be clicked on for a larger version. Measurements are in Counts Per Minute, the graph logs 1 hour of data.

 

The counter itself is a Sparkfun Geiger counter, with the end cap removed from the tube so it can also detect alpha radiation.

Connected through USB, a Perl script queries the emulated serial port for the random 1 or 0 outputted by the counter when it detects a particle. The graph is pretty basic, but it gets the point across. Anybody who wishes to contribute to improve the graphing is welcome to comment!

Geiger Counter
Geiger Counter
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Kidde Smoke Alarm

Top
Top

Old type ionization smoke alarm. Top of the device with the test button & sounder.

Bottom
Bottom

Bottom of the device. Battery compartment in centre.

PCB
PCB

Internals of the smoke alarm. Main component visible is the Ionization chamber.

Sounder
Sounder

Piezo sounder on inside of the top.

Ionization Chamber
Ionization Chamber

Inside the Ionization Chamber. 1µCi Americium-241 alpha particle source in the centre.
The radiation passes through the chamber, between the pair of electrodes, ionizing the air & permitting a small current to pass between the electrodes.
Any smoke that enters the chamber absorbs the alpha particles, which reduces the ionization and interrupts this current, setting off the alarm.

Controller
Controller

Controller IC beneath the chamber.