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)      
SI19BG    (alpha beta and gamma)
Beta-2      (alpha beta and gamma)

Beta-1-1   (alpha beta and gamma)

SBT10     (alpha beta and gamma)
SBT10A   (alpha beta and gamma)

SBT-13     (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!

Firware modification by Nic Wilson from Australia

Nic Wilson from Brisbane, Australia has bought quite a few of my Geiger counter boards over the years. He has also put a lot of work into the open-source GeigerKit firmware and agreed to share his branch here, together with a set of documentation he wrote for it. Thank you, Nic!

GEIGER by Nic SBM-20 11.1.13

Download Nic's firmware and documentation (ZIP):
Short link: https://tinyurl.com/firmware-nic
Full link: https://www.dropbox.com/scl/fi/0317rqvvqlfkezja1azxq/GeigerKit.zip?rlkey=hh4zt77do85620wzkp9yg7yy1&st=jkkfuhw2&dl=0

About the version numbers

Version numbers in this firmware (11.0.5 up to 11.1.13) are Nic's branch versioning. They continue from the 11.0.x numbering of the original GeigerKit sketch (bHogan / DIY Geiger Counter) and my SMD adaptation (v11.0.2), but they are not official upstream releases and are not tracked in my repository. If you report an issue, please say "Nic's branch 11.1.x".

Release status

11.1.5 is the last fully documented, hardware-tested baseline (button menu, tube selection and startup changes tested on two boards).
11.1.13 is the current build. It adds selectable IR remote profiles and is marked by Nic as a test build until remote operation and EEPROM persistence are confirmed on hardware.

What Nic changed

Full settings menu without a remote

Nic's favourite feature. Hold MODE and TONE/ZERO together for about one second to enter the settings menu, then release both buttons. The IR remote still works, but is no longer required.

In the menu	Action
MODE short	Save and go to next item
MODE double	Save and go to previous item
TONE/ZERO short	Increase / change value
TONE/ZERO double	Decrease / change value
MODE long	Save and exit

Pulse counting continues while the menu is open.

Tube type selection

New TUBE TYPE menu item with three presets. The choice is saved in EEPROM, shown at startup, and automatically writes the matching ratio to both primary and secondary RATIO values. Manual RATIO adjustment is still available.

Tube	Preset
SBT-11A	318 CPM per µSv/h
SBM-20	220 CPM per µSv/h
SI29BG	100 CPM per µSv/h (project preset)

Faster startup

Startup now shows only "GEIGER by Nic", the selected tube and the firmware version for about 1.5 seconds, then goes straight to the live CPM/dose display. The ratio/voltage splash, alarm prompt and other startup pages were removed, as these settings are now in the menu.

Diagnostics mode

Long-press MODE during normal operation to open six diagnostic pages; MODE short goes forward, TONE/ZERO short goes back, MODE long exits. Pulses keep counting in the background, and timers restart cleanly on exit.

Page	Shows
1	Firmware version and hardware ID (SMD v2.0.1)
2	Active calibration ratio and dose unit
3	Pulses since entry and supply voltage
4	Current / minimum free SRAM and uptime
5	Reset cause (POR, EXT, BOR, WDT) and CPU clock
6	EEPROM map identifier and build date

IR remote profiles (11.1.13, test build)

New REMOTE TYPE menu item, saved in EEPROM: NEC ORIGINAL (the original 21-key remote), NEC LED (a common RGB LED-strip remote) and SONY (Sony SIRC TV remote). An IR TEST page shows raw received codes and can decode NEC, Sony and Philips RC5, which helps when trying an unknown remote. RC5 is diagnostic-only for now.

Reliability and code fixes

• Atomic access to the 32-bit pulse counters, so the 8-bit AVR cannot read a half-updated value.
• Bargraph, version-text, tone arithmetic and analog-meter signedness fixes.
• SBT-11A calibration audit and flash-string cleanup.
• Changing display mode now also applies the matching ratio (previously done by hand).
• INFINITY renamed to INFINITYVAL to avoid a clash with Arduino.h.
• Measurement maths and the existing EEPROM layout are preserved; no migration is needed.

Full change list

Version	Change
11.0.5	Ratio follows display mode; INFINITY renamed
11.0.6	Frozen working baseline
11.0.7 b1–b6	Atomic counters, bargraph/version fixes, flash strings, tone fix, meter signedness, SBT-11A audit
11.1.0 a1	Hidden diagnostics mode on the 16×2 LCD (hardware tested)
11.1.0 a2	SRAM tracking, CPU frequency and build info (hardware tested)
11.1.0 a3	Reset-cause capture, hardware ID, informational EEPROM map v1, six diagnostic pages
11.1.1	Unified tube selection, tube shown at startup
11.1.2	Full two-button settings menu (hardware tested)
11.1.3	TUBE TYPE menu, EEPROM-persistent (tested on two boards)
11.1.4	Simplified startup (hardware tested)
11.1.5	Live display drawn immediately after banner (hardware tested baseline)
11.1.6–11.1.9	IR TEST page, raw NEC display, receiver activity and burst diagnostics
11.1.10	Selectable NEC / Sony / RC5 test decoders; Sony remote mapped
11.1.11–11.1.12	RC5 experiments; LED-strip remote confirmed as NEC
11.1.13	REMOTE TYPE profiles: NEC ORIGINAL, NEC LED, SONY (test build)

Normal-operation buttons

Gesture	MODE	TONE/ZERO
Short	Main / scaler display; silence alarm	Set tone zero point
Double	LCD backlight on/off	Mute / unmute
Long	Diagnostics	Primary / secondary ratio
Both ~1 s	Settings menu
Held at power-up	Reset EEPROM to defaults	–

What's in the ZIP

• Arduino sketch: GeigerKit.ino, GeigerKit.h, Menu.ino, IR.ino/IR.h, Meter.ino, PinChangeInt.h
• User Manual, Button and Menu Guide, Technical Reference, Engineering Notes, Changelog (Word format)
• Button menu quick guide (text)

Hardware target: ATmega328P at 10 MHz, 16×2 HD44780 LCD, SMD board v2.0.1.

This firmware is shared as-is by Nic for the community. A Geiger counter built from this kit is an educational instrument, not a certified dosimeter. The high-voltage section carries several hundred volts — disconnect power before working on the board.

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.

Nice instructional how to connect geiger counter to HomeAssistant over TTL-Serial to USB adapter by BY ROEL VAN WANROOY

If you want to quickly get geiger readings to your HomeAssistant

Please check his LINK on Roel VanWanrooy's blog

Courtesy of Dion from Holland, here are pictures of neat and compact 3D case design of a geiger clicker circuit based on the HV module and si-29bg tube

 Dion has gracefully provided these nice pictures of the enclosure. It is HV module based clicker circuit and si-29bg tube. On the top you can see the potentiometer knob which is used to switch the device on and to regulate the volume of clicks. Dion says he used a generic PAM8403 pcb from aliexpress.com and a speaker.

To compare the size to the stock 3D printed enclosure:

Have just received PCBs for the UPDI programmer

 I have just received PCBs for a "HighVolgage" (12V) UPDI programmer featured here:

• See info at Arduino IDE-Compatible UPDI Programmer Allows for Safe ATtiny Configuration Experimentation
• Arduino Nano HV UPDI Programmer (GitHub) for the BOM, etc.

I have some spare pieces so if you need one please secure it until the stock lasts as I am not planning to get more. You can click-purchase (9,99 EUR + 4 EUR shipping) here :

Here is a new enclosure design for the counter electronics with the SBM-20 tube for 3D printing by Marius

 Here is a nice new design of the enclosure for 3D printing by Marius.  It is made in OpenScad so easily modifiable.

Many thanks Marius,  for sharing!

OpenScad and .stl files can be downloaded from this link  or from Thingiverse

For complete visualisation below are pictures of the make cortesy of Sergiu from Romania.