Need a simple interface for connecting GM tubes to geiger counters? Use  1/4″ /6,35mm TRS sockets and plugs. It’s not what these plugs and sockets were designed for but it works nice. I use the tip as positive, ring as return and sleeve for ground. Two wires are sufficient to connect geiger tubes but the sleeve is connected to the ground of the circuit and to the shield of shielded cabling. You can also solder geiger tubes directly to the plug, I have done this with a SI-29BG tube and it works fine. Read more »

Above is a picture of my recently (practically ) finished project. It is a sort of weather station which measures light, temperature, relative humidity, atmospheric pressure, and of course radioactivity!

The core of this setup is the excellent DIY Geiger Counter PCB by [Brohogan]. This kit is a geiger counter circuit combined with a standalone Arduino circuit. Most people buy this kit, connect an LCD and put it in a nice box. Because the Atmega328 pins are broken out via handy pin sockets it is very easy to connect any additional components and/or sensors to this PCB. Read more »

My online geiger counter which I described earlier has been offline for some time. During that time I experimented with a standalone Arduino with the goal of making a dedicated board for the setup. I have now completed the board shown in the picture below.

In the picture you can see the HV generator on the top of the board, on the lower left the Arduino standalone parts along with a MAX232 as a level converter for easy serial hookup and on the right two tubes connected in parallel, a SI-29BG (beta and gamma) and a SI-12B for added alpha sensivity. Also shown are the USB>Serial adapter and a separate USB connector to provide 5V to the board. Read more »

I own a CDV-700 geiger counter of which the tube stopped working. It turns out that replacement tubes are both hard to find and expensive. The simplest option is to buy the LND 720 which basically is a drop-in replacement that should cost about $100.

It’s also possible to use cheaper, easier to find tubes with the CDV-700.  I found the following post from radio amateur K0FF on the “Geiger Counter Enthousiasts”  group on Yahoo groups. It describes a simple circuit to adapt tubes of varying voltage to the CDV-700. I built one, and it works! Read more »