So with a fully working proof of concept it's prototype building time. There's still a few tests to run (see the bottom of this post), but the results impact software, not hardware. It's time to build. Currently I only have the parts (due to finances) to build three. I want to build a minimum of eight ideally to prove this system's effectiveness in complex orienteering and staged situations.
You'll notice in the bottom right the remains of Anker battery pack - this was taken to pieces to reduce it's size. It was effective. The circuit with the transistor is in the top left, next the the external RTC. This positioning allows more space around the Pyscan and FiPy for connections to power and the mounting of a small Li-Ion.
Why use the disassembled Anker and not a larger Li-Ion? Principally cost, but also it allows 5v to be taken off for the buzzer and LED circuit.
All that's left to do is the final power circuitry (mainly the switch) and mounting the FiPy. Here a couple of photos showing the detail of some of the fittings.
Lastly, the remaining tests-
- Data usage test - I know it's low, question is how low
- Cell transfer test - how does NB-IOT cope with moving cells?
- Power usage test - there is at least 36 hours in the Anker packs. How much more?