DIY/Homemade Radiation Geiger Dosimeter

An efficient, stable, easy to build construction for all your radiation dosimetry needs. I started from scratch, designing a complete dosimeter unit around the Atmel Atmega8 microcontroller and a Russian Geiger Muller tube. Here you`ll see the CTC-1 tube, for high gamma doses, but the dosimeter can be used with any other tubes such as SBM-20, LND-712 or more sensitive ones such as the SBM-19
DIY/Homemade Radiation Geiger Dosimeter - schematic

or the pancake tube SI-14B. Changing the tube requires changing the software, to adjust the dose conversion calculation. This circuit can be used with almost any geiger tube, as even the inverter`s output voltage driving the tube is adjustable in the software. 1. Generates a variable duty PWM signal using Timer1, to drive the 400V inverter needed to operate the Geiger tube; The inverter doesn`t need a multiplier, as the ferrite`s transformer secondary puts out exactly the amount required. The transformer is made on a A22 ferrite core, with 16 turns in the primary and 600 in the secondary. Some other circuits on the Internet come with improper 400V inverters (some people seem not to be able to design a proper inverter), they are redundant (using 555`s and additional components, when the microcontroller can take care of EVERYTHING), use the wrong signal detection/counter circuit, or other small defects that result in wrong measurements. Not to mention the complicated aspect of computing dose in sieverts out of counts per minute. Given all these wrong designs, my detector tries to fill in some of the gaps. So here is exactly what you need: a stable design, with several improvements made over time, all packed in this nice construction that you can easily replicate. Before getting into the construction details, and the theory involved in my geiger counter, here are some pictures of my construction. I might use them later to...

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