RH Electronics Arduino Geiger Counter

 Feeling a little flush (this being before I was suddenly hit with an expensive DEFRA poultry housing order!) and really not liking doing my own coding, I decided i'd give the RH Electronics Arduino IDE Geiger Counter kit a try. ( https://rhelectronics.net/store/arduino-ide-geiger-counter-dosimeter-diy-kit-with-lcd.html ).

I placed the order for this on the 10th of December. Coming from Isreal, the package arrived on the 4th January.

The shipping label clearly shows that it was dispatched on the 12th, so considering the Christmas period and all the other disruption to postal services at the moment, I dont think thats bad going.

Inside the box, which was well sealed, the kit itself was securely shrouded in bubble wrap, and although there are no detailed instructions for the build, the included schematic is clear and relatively easy to understand. Its perhaps not a beginners kit as it stands, as putting it together does require a reasonable knowledge of the components and how to read the schematic.

The actual electronics package of the kit consists of the LCD module in its own wrapping, and all the other parts in a small self-seal bag. There is hardware supplied for mounting the LCD. Not supplied is a G-M tube or mounting hardware for it. A G-M tube could easily double the cost of the kit! The LEDs and buttons are PCB mounted - these will have to be reworked when the unit is fitted into a case. 

The circuit also runs on 5V and there is no on-board regulator. Personally I think this is a bad oversight by the designer, and a low drop out 5V regulator should have been included. I will see if the unit will run reliably on 3-4.5V (2 or 3 AA cells), if not then I will modify it with a 5V regulator for a 9V PP3 battery.

The circuit uses a clever PWM HT generator driven by and feedback monitored from the ATMEGA328 microcontroller, but otherwise the G-M electronics are pretty standard. All the clever stuff is done in software. LEDs and a buzzer are included for the traditional 'geiger counter' feel, and it is capable of driving 400v and 500v tubes with just a jumper change. This will work with all my tubes except the alpha tube, which requires 1600v. A header is provided for serial comms to other devices.

I plan on including a socket to connect an external tube (probably my huge STS-6), as well as the internal one(s).  With a suitable switch, I plan on installing a standard SBM-20 tube and the tiny SI-19 tube within the case.