With all this talk of pollution in the form of NOx and particulate matter in the air, no pun intended, I thought it would be cool to try and measure some of this locally using a Raspberry Pi.
I had the idea to try and run this off a Pi zero due to its low power consumption along with a PMS7003 particulate sensor and a MiCS 4514 gas sensor (or similar).
The project needs to:
- Measure NOx Levels
- Measure PM 2.5 and higher
- Measure Temperature and Humidity
- Solar Powered with backup battery – run time ideally 24 hours or longer
- Be able to self-restart when power has been lost completely.
I have started off focussing on power. Rather than look to build my own charging circuits and battery pack I thought I could get away with using a Power Bank Battery pack. Turns out its a lot harder than you think getting one that will deliver power in all circumstances and also not require a button to be pressed to deliver power.
After ordering lots of different models on Amazon I cam across the Ravpower RP-PB41(B):
This will deliver power whilst being charged, will not stop charing if power is interrupted. Essentially this will act as a UPS, which is exactly what I want for a solar powered system.
The caveat is, it will only do this on one port, the lower power port. This is sufficient for me as now all I have to do it get a regulated 5v supply from a solar panel and I have a complete solar power system for the pollution sensor.
I’ll cover the build in the next few posts but the idea is to get an IP rated box with cable glands allowing a hose to pass through to the relevant sensors.
The sensors are on order so will hopefully progress soon 🙂