Geiger Telescope: Electronics

Today I finished sketching up the last PCB for the first version of my Geiger telescope. This is a scaled down attempt with only 4 tubes, and uses ESP8266 as the brain. I picket this MCU, because you run-of-the-mill Geiger tube needs approximately 500V to operate. By Murphy's Law, the moment I plug my contraption into the USB port, it would immediately apply high voltage data-lines.....

At the moment the telescope is spread across three boards.

  • HV_PSU: a high voltage power supply. Most of the design is borrowed from here. This PCB is a transistor based DCDC converter with voltage doubler on the output. If I did not stumble on this design I would have probably let the MCU control the FET. In the end though I feel that keeping everything modular made testing much easier.

  • HV_DISTRIBUTION, this board biases and distributes high voltage across the 4 Geiger tubes. It is also responsible for converting the Geiger tube signal to logic level.

  • LOGIC. This is a motherboard for the ESP8266 which reads the tubes and sends the data to the cloud. Once I move to an 8 tube device an FPGA will take over the analysis, but an ESP8266 will still be used for talking to the outside world.

Anyone who is familiar with PCB design would quickly notice that the tolerances on these boards are HUGE! I recently finished putting together a PCB router, and my goal is to create all of my PCBs at home. As I get better at using my machine, my tolerances will improve, but for dealing high voltage large isolation cuts is not a bad thing anyways....

Distribution

Hooked up