Geiger Counter

About five years ago I recieved this russian "Bella" geiger counter as a gift. Since then I wanted to build my own, but somehow I always failed. Now I'm the proud owner of a selfbuild and designed geiger counter! 
It took me three months between prototyping and the finised PCB design. If I'd be still at school, this would've been done in a week.
The geiger works of a 9V battery down to 6V. At 9V it takes 10-15mA. I made a series of tests with different geiger tubes and uploaded the videos of the tests to my youtube channel:


1. SBM19  Most sensitive one, for beta and gamma.

 

2. SBM20  Probably the most well known geiger tube. Not that sensitive, but small.

 

3. SI-22G  Largest geiger tube, but come's second after the SBM19 in sensitivity.

 

4. RFT VA-Z-114  Least sensitive one, only for hard gamma radiation.

 

During the holidays I upgraded the Geiger Counter to a much more durable version, than the one with the plastic case I made during the semester(from which I don't have a foto). It has a aluminum case with the Geiger Counter board and the battery in it. The Geiger Tube is now external and connects to the main unit via BNC. Togheter with that I have battery voltage, pulse output and the divider output from the HV-divider on a five pin DIN connector, so I can attach a display module later. At the moment I have the pulse output wired to a microphone jack, to use a PC or laptop as a counter. 
The handpiece of the the Geiger is a steeltube with holes drilled into it, so beta radiation can pass through it, wich the steel would otherwise block. Since the used Geiger Tubes can  measure beta aswell, that only made sense to do.
Credit for drilling the holes goes to a friend. I suck at mechnical work so he drilled the holes for me. A big thank you goes to him and check out his Youtube channel!

 

Update! 
I ditched the old case and made a much for fancier case for the Geiger, with display and three SBM20 in it + a handle to hold it more easily! I also have a version installed permanently at home, with a dc input jack and a 6.3mm jack to connect it to a remote display. The pulse out is still there.
Don't mind the battery in there. It was before I decided to permanently put this Geiger into my appartment.
With new cases for the Geigers, I also made a new PCB, which is slightly smaller and a universal microcontroller PCB with a AT-Mega32. 

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:D