"Sentinel" Geiger Counter Housing for Handle Geiger Counter

thingiverse

This is just a demonstration software for a small, USB-powered Geiger counter with display and speaker that alerts if counts per minute exceed a threshold. The goal is simply to let it run and sound an alarm when radiation levels get too high. Costing around $100 for parts from Amazon, Adafruit, Mouser, etc., it also reports accumulated counts every minute on the USB port in plain text, one minute's reading per line, if anyone wants to log or analyze. The Geiger counter is a widely available and reasonably priced "Portable Handle Geiger Counter 0.01 μSv/h DIY Kit Nuclear Radiation Detector With Geiger-Müller GM Tube Gamma Beta Ray Suitable for Arduino". I included a mounting pocket for an Adafruit 5V ItsyBitsy (https://www.adafruit.com/product/3677), a small speaker (Mouser.com part number 490-CMS151135078L100), an Adafruit 128x128 OLED display (https://www.adafruit.com/product/1431) and a couple of capacitive touch switches (TTP223 Capacitive Touch Switch Button Self-Lock Module for Arduino) to build a complete system that graphically and numerically tallies counts and alarms if need be. The display frame mounts to the main box using 2x M3x5 screws. Four more M3x5 screws secure the Handle Geiger Counter into the box. The holes to mount the cover that came with the Geiger counter were offset slightly on the cover so other covers may or may not carry that same offset. Hopefully, they are all identical but no guarantees. The ItsyBitsy records the Geiger counter events and keeps a running minute-by-minute count. If levels cross a threshold, it sounds an alarm using the pancake speaker and lights up the OLED display (wip). A computer connected to the micro-USB port on the ItsyBitsy can log and timestamp activity for longer history but this is just a simple running display of counts per minute vs minutes of time. Touching a capacitive touch switch lights up the OLED for a few minutes as well as switches between graph and numeric displays (wip). I blank the display and only wake it up when a capacitive switch is touched or if in alarm since it's OLED. The capacitive switches, ItsyBitsy, and display are all held in place with thin double-stick foam tape. I also cut a piece of card to put between the ItsyBitsy and the Geiger board to keep the wires insulated and away from any high voltage spots on the back of the Geiger board. The card can also prevent screws or nails in the keyhole slots from being able to touch the Geiger board. The main box is 119 mm x 70 mm x 20 mm, while the display frame is 100 mm x 60 mm x 10 mm. The software may have bugs but looks okay so far. It now also computes and draws a least squares straight line fit through the data. It also displays the average count and slope of the counts numerically. The firmware has an alarm level now and will sound if the average count goes above a threshold. There's also a current count value in the lower right corner of the display, a red horizontal bar showing the alarm level, and the best fit line of the count data is now black for better visibility. The alarm level is still a #define. More to go but 0.6 exercises everything except the SD card reader/writer so all of the hardware can be tested. Higher functions are still missing. The alarm is a bit softer than I thought it would be. Harder to hear outside a room.