I finally got out in the garden again to day to complete part 2 of my bumblebee sensor project.
The system has been up and running for a week, measuring temperature and light levels, but I needed to tackle two things:
- The outdoor temperature sensor was too exposed and over-reading in direct sunlight; and was too close to the garage wall, so also picking up heat from the wall
- I still had to finish constructing and fit a flap sensor to monitor activity in and out of the nest
For the thermometer, I hacked a small bottle apart and fixed it up with my new favourite "stuff for making things with": Sugru. Here is is below with the iobridge board in the background.
Next I just spray painted it with some plastic paint - so it would blend in a bit and be protected from sunlight. Only a rough job - good enough!
The thermometer (white wire) runs up a small tube in the neck of the bottle where it is shieled from the elements. Then it is simply mounted on a cane round about nest height, and away from the garage wall.
In comparison with our wireless weather system, my DIY thermometer was only reading 0.2C difference, which I am very happy with.
Next up was the flap sensor. Getting a good flap sensor running has been critical for me this year, because I want to use it to closely correlate activity data with enivronment data. I was only able to do this last year in a minimal way because it's so labour intensive (to do from CCTV).
While this initial system will not give me the reliability required to accurately count bees in and out (it's not directional anyway) what it should do is give me activity levels throughout the day (e.g. first, last, flights during bad weather etc.) which will definitely be a step forward.
The system is comprised, essentially, of an alumiumium foil strip attached to the side of the flap that acts as a make/break switch on the ioBridge digital input. When the flap is closed, the circuit is made, and the digital input is held low. Once a bee pushes through the flap, the circuit is broken, which generates a digital pulse that the ioBridge board can count.
It's taken quite a bit of experimenation to get the inputs working in a way that is meaningful. Opening and closing the flap doesn't just generate a single pulse but can generate many (the bumblebees themselves very rarely just open it cleanly - but push against, causing it to open and close); so I can't rely on this basic circuit to count single open/close of the flap.
But it doesn't really matter as the system will count the total number of activations and report this every 10 minutes. These 10 minutes slices will give an indication of the overall activity level, and in particular detect things like 1st & last exits, which I'm particularly interested in.
This is only a phase 1 system - to get me started and get some data collected; I have ideas/plans for two further developments of this system - one using a light beam sensor (this would solve the problem of the flap being so busy that it actually gets held open and only counts a single pulse for many bees) and also a non-contact displacement sensor which will measure the exact angle of opening. Ideally a combination of these two would be good - but I don't have enough inputs at the moment.
So, I have to wait for a few days now to collect some data and see how the system performs.