Introduction

There is radioactivity. The radioactive rays are invisible. We are suffering from it. The sun is a nuclear fusion reactor. Are the radioactive rays dangerous? How far do we take a distance from radioactive obstacle for our safety?
I had lots of questions. First, I had wanted to measure radioactivity to understand the effect from the field.
Geiger counter, dosimeter, is a measurement device. But it is very expensive.
I made a sensor, geiger muller tube, with low cost. And I had success to count it.

Caution:
Use this document at your own risk!
Danger high voltage in the geiger counter.

The Air Geiger Counter Kit has been launched by Bit Trade One, LTD which I have licensed. In detail http://j-kosaku.jp/