An entry into Hackaday's Trinket Everyday Carry Contest. This project will use a LiPo battery powered Trinket, a small circuit, and a photodiode to detect gamma radiation. I have not yet decided how to display the count, but am thinking about using some dense NeoPixels with a smooth fade/decay effect.
Over the past week, Black Friday/Cyber Monday sales were a great excuse to purchase all the parts. The only things outstanding are a few 47pF caps that need a newark or mouser order. I'll post the formal component list later in the month once the schematic is finalized.
One mistake so far- I accidentally ordered a Trinket non-pro from Adafruit instead of the correct "Pro" part. Rather than pay $8 shipping to order a replacement, I bought a Pro-version off a fellow maker from the local Makerspace, so I know its got good juju.
I also took the opportunity to start populating the headers on the Neopixel board and the Trinket Pro, as well as to start writing some of the code.
After spending a few hours reading through the linked articles below, I'm beginning to get a better idea of the theory behind using a diode to detect radiation. There are still more questions than answers at this point. Most of them revolve around component substitutions (whats the need for that now obsoleted JFET in the Improved Radiation Meter circuit?) and how I will be able to test the in-progress circuit and final device. I'm also doubtful that the 5V reverse-bias voltage across the diode will produce enough signal to amplify. I may need to get another step-up convertor or add a second power source such as some coin cell batteries.
I'll be basing my design largely off of the Improved Radiation Meter circuit (image above copied from the PDF), with a few subsitutions. Instead of the Atmega88, I'll be using a Pro Trinket. I won't be using an LCD for output, rather a small Neopixel strip and a vibration motor. The whole circuit will be powered by a LiPo battery and stashed inside an Altoid tin with some windows cut for the Neopixels.
Adafruit's BlackFriday sale gave me the kick in the rear needed to buy the parts, also 15% didn't hurt.