I previously posted on my first effort building the first complete sensor from OSBSS, a long-term battery powered temperature and relative humidity data logger (revision 09 30 2014), as well as about a week’s worth of data sampling at 1-minute intervals in my office and co-located next to an Onset HOBO U12. Just to test the battery life and clock drift, I’ve left it running since late September until yesterday (December 10, 2014), logging at 1-minute intervals in my office for a period of about 73 days. The sensor and data logger are still functioning normally even at this high resolution of data collection and powered only by AA batteries! The clock appears to have drifted minimally (maybe 5 seconds, although I can’t confirm that). See below!
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Data from custom T/RH data logger – 1st build (revision 09 30 2014)
Two months ago I wrote a blog post documenting my first OSBSS build of our low power (long battery life) air temperature and relative humidity data logger. At that time we were using the SHT15 sensor breakout board to measure both temperature and relative humidity. After some co-location tests with Onset HOBO data loggers and others, we discovered that (a) yes we could achieve low power draw and long battery life on this base framework of a data logger, (b) yes we could achieve accurate relative humidity readings compared to a HOBO, but (c) unfortunately, our temperature readings were not very accurate (they were decent after calibration, but who wants to build a temperature sensor that then has to be calibrated against another, better temperature sensor!?). This last part really bugged us — we simply couldn’t rely on the SHT15 to provide accurate temperature measurements, which then, because RH is based on temperature readings, yielded both inaccurate T and RH readings.
Custom T/RH data logger version 0.01 – First build
Yesterday marked a momentous occasion for OSBSS: our first complete build of a custom sensor by a non-expert (me!) using our first online tutorial. After about 9 months of work and many stops and starts with various boards, sensors, software, and design concepts, the development team (Akram Ali and Zack Zanzinger) has successfully developed their first low power data logger built on the Arduino platform. It even has its own GUI to launch the logger! The first logger is designed to measure temperature and relative humidity (read the tutorial here). But the really cool thing is that now they have the basic design for a custom data logger with low power draw and a long battery life that can be used to accept any number of other sensors that we are planning to build. We have already prototyped and sourced many of these others sensors, which, combined with the background legwork Akram and Zack have done, should allow for fairly rapid prototyping of new sensors and tutorials. Not bad for a team of architectural engineers without formal electronics training!
