Well… I will build a “docking” station later… The multiplexer autoswitch is switching between the two inputs. The primary input will be powered from the AC input, while the secondary input wil be powered is powered from battery. The multiplexer and the Kit1 will be in the same enclosure.

Finished soldering the kit, but due a bad soldering (cold join) of the MPSA42 transistor the kit would not detect anything (the HV voltage for the Geiger tube was missing).
After solving this (Thank You Radu for your commitment, time and help!) I needed a case.
Since I don’t own a 3d printer, neither have access to one, I had limited options for a case: to buy one, and wait for it’s delivery, to make one using plastic sheets, plywood… etc OR to adapt something.

I’ve chosen the last. I’ve found a plastic food container and using an utility knife and a dremel tool I cut the holes for power, network and a hole for my custom made push button rod. In order to create a sturdy push-button rod, I’ve used an old banana socket, a screw and a nut of 30 X 4mm and half spring from an old pen. I’ve put a dab of epoxy on the end of the rod, so that the metal of the rod would not damage the soldered push-button

I have a similar issue…
just finished soldering kit1… powered up…
but the geiger tube voltage is…1Volt.
If I play with a metal object around the tube, I get one beep each time and strange readings on the screen…
I assume I’ve received a bad geiger tube? Or I did something wrong while soldering !?