https://www.crowdsupply.com/envox/eez-bb3

Nice article .. Good job !! very helpful  Nikhil   

PIC microcontroller code (in XC8) is now complete and fully functional for the prototype hardware. Shut-down timing is computed in real-time based on the state of charge of the supercaps and their rate of voltage drop. The mechanism provides 15 second warning of critical capacitor voltage loss independent of o/p power consumption and size of the super-caps.  A bash shell script running on the Pi (as root) initiates a clean shutdown upon request from PoEUPSPi via a GPIO pin.

Apparently the A2035H is no longer in production. Maestro has the A2235H, a newer GPS module that does fit on our PCB (although the module is smaller than its predecessor), but it needs two additional 2k2 pull-up resistors from the I2C pins to the 1.8V output of the module. You may also need some (kapton) isolation between the PCB and the module to avoid short circuit between the shielding of the module and a via underneath it.

Dear Tarsonis, you are correct about the low count rate. We also measured a few counts per minute with the pin-diode based detetctor. The area of the diode is just too small and covers a very small fraction of the 4*pi solid angle. We asked the schools to do a "calibration" with Potassium salt, which is readily available in grocery stores and report their findings, which are stored in some spreadsheet. But they also typically report a few ccounts per minute. The details of the "calibration" are described in the teacher's guide, available from the project web site referenced in the post from April 26. The result of the HPGe detector are encoded on the first map, referenced in my reply from May 1 below. If you click on the respective mushrooms on the map, details about the schools and their send-in samples are displayed on the left. You'll see that the maximum rate (~2000 Bq/kg wet weight of mushrooms) comes from around Sundsvall. My colleagues also prepared a map, where they converted the Bq/kg values to the number of 200g sandwiches with mushrooms you can eat without exceeding any legal limits. Thats shown on the other map from my may-1 post. Here the idea is to provide some gut-feeling to the (typically 8th or 9th grade) pupils what the more abstract Bq/kg readings mean in practice.