by weirdlab.fr:
I “rebuild” my Geiger counter, the SBM-20 tube was initially inside the box, i have put this one inside a 32mm diam plastic tube, for more convenience, wired through a XLR3 cable. This counter is from “Electronique-Pratique” n°368, a french electronic magazine. Shem, pcb, and PIC hex & C source code available.
Geiger counter with SBM20 tube – [Link]
broken link http://www.f4huy.fr/?p=789
Check for this project here: https://www.electronics-lab.com/project/geiger-counter-with-sbm20-tube/
it works very well! works very well on LCD16x2 and PIC18F2550, without modifications