If you need a complete kit assembled or unassembled,  or just a PCB, a partial kit or even just some component,  please feel free to contact me at the e-mail address below.
Also I have in stock following geiger-muller tubes:

SBM-20  (beta and gamma)
SBM-20U (beta and gamma)
STS-5     (beta and gamma)  
SBM-21  (beta and gamma)
SI22G      (gamma)                        
SBT-9      (alpha beta and gamma)
SI-29BG  (beta and gamma)      
SBT11     (alpha beta and gamma)
SBT11A   (alpha beta and gamma)
SI19BG    (alpha beta and gamma)
Beta-2      (alpha beta and gamma)
SBT10A   (alpha beta and gamma)
SI8B        (alpha beta and gamma)

Please check  THIS eBay LINK or contact me directly by e-mail :

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Best if you write to me in English,

but you are also welcome to write to me in Russian, Polish, German, Italian or French.

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Best regards!

ESPHome integration for Arduino Geiger PCB by Nicola

For your consideration, here's a very neat project kindly shared by Nicola to connect the geiger counter to HomeAssistant.

link to project page on GitHub

It uses the serial interface to read the CPM value, convert it to an integrer and expose it as a sesnor that can then be integrated into Home Assistant.