About a year ago I bought and assembled the open source and open hardware Geiger counter by MightyOhm at the Chaos Communication Congress. Since this device does not have a display to show the current measured values, I extended it by some hardware to do the job. I’ve used a ESP8266 SoC by Wemos and connected a cheap OLED display via i2c. The measured data is send from the Geiger counter to the ESP8266 via UART. Since the ESP8266 has WiFi capabilities, the measured values are not only shown on the display, but also on a small web page.
