This is not a song from Kraftwerk but a real little Geiger counter...

While wandering around once again, I came across this kit, with the specificity "Arduino Compatible", which I bought.

I figured it must have a UART and it would be fun to interface it with a PC or something.

No UART in sight, not even a microcontroller, just an open collector output which is briefly grounded at each sound signal.

The kit arrived assembled (:-() and is very clean. The assembly is based on a cheap Chinese tube.

The high voltage, supplied by an oscillator and a charge pump, is adjusted via a potentiometer, with measurement on an incorporated divider bridge. Convenient.

The only thing, the tube supports were not at the correct center distance, a modification was necessary.