The low 15V tube voltage is also displayed on-screen (KIT1 screen, not multimeter).
I have measured R3 to ground: 8.5 Mohm. R3+R5 to ground: 17.2 Mohm (with the tube in circuit).
I suppose M1 has only 2.7V because I use 2xAA batteries to power the kit.

Thank you so much, Wolferl! I will send you the modified source code.

I would love to read that tutorial too, when it might resurface.
I started this project because I want to familiarize myself with both
programming in general and microcontrollers in particular, so I chose
something that interests me.

Hi Wolferl!

My mistake… I meant the internal voltage measurement is 15V, as it is shown on the LCD.
The LCD is powered at 3V (2xAA batteries).
I have replaced the small axial inductance (2.2 mH, 32 ohms) with a larger, ferrite-core one (2.2 mH, 3 ohms),
but the voltage remained the same.

@Radhoo, thanks for your benevolence; it was not my idea, I just quoted from your #3932,

<<As said, it was a “competition, for all those that post their construction here. We’ll have some voting in place, and the nicest build wins a model A2 detector. DIY units go as well.”>>

Seems like I misunderstood that quote. I’ll look forward for future chances to win a nice kit! It’s really great that you are offering this to us!

My DIM (do-it-myself 🙂 version, still under development. I’m using a very sturdy Gainta enclosure for portability. I hope that my personal touches would not disqualify me from this contest!
The protective window has a narrow overlapping edge (grinded by hand, just like the opening hole) that prevents it from falling inside, should it be pushed hard from the outside (it would be glued anyway). The very edge of the edge will be chamfered to fit more snugly with the front panel.

I have recently dropped the idea of using the 8-pin connector of the LCD board; the LCD will use the 4 thick but pliable copper wires not only as a precisely 3D-adjustable support but also as electrical connections, together with another 4 flexible wires that will connect to the main PCB in various points – that would simplify my PCB design a lot (the enclosure is quite spacious, the PCB not as much).
The power switch is mounted on the side, under the enclosure’s shoulder, to protect against accidental flipping.

The center metal button has a white LED inside, that will blink in unison with the sound from the internal speaker. This button and LED will have internal counterparts (selectable via jumpers), to allow testing without having the cover in place.

Hello, Radu!

I’m building a portable one based on STS-1 (that’s what I had nearby). I already have all the parts, I’m working now to position parts on the PCB
that suits my case (Gainta 828G-S-BC).

I know that you have used the same model on your previous prototypes, can you please tell me what factor to include in detectors.cpp? I will add STS1 in detectors.h too (at number 9).

This particular prototype would not be used online. When I would decide to become part of the community, I will use a tube that would allow uniformity between my measurements and the rest of the network.