So the weekend mini-project was to read out the light sensor (an LDR with a 10k resistor in series) at one of the outdoor wireless thermometers that sends its measurements every so many minutes to the router. And from this we can get the rise and set times which are plotted. The jumps are the transitions from daylight savings time. The other thing you see is that the point of earliest sunset and latest sunrise do not match. This is related to your position on Earth, the orbital parameters of the Earth’s orbit and the obliquity of the rotation axis relative to the ecliptic. In principle you could try to estimate where I live from this data, the times are local, the only thing you need to know is that it is somewhere in our GMT+1 winter timezone. The scatter in the plot is caused by the way sunlight projects into the sensor, the LDR sees the northeasterly skies and during sunset it observes the shadow of the house, while at sunrise there are some trees in the garden.
I got his sensor at Maplin two years ago in the UK (there are no Maplin shop in the Netherlands) but did not look at it for a while, until I had some time to have a look at it this Easter.
Mount the sensor somewhere under a laminate floor or a doorstep (I gave it a small 3D printed pillbox to somewhat protect it). But as soon as you do this then the signal becomes really small, furthermore there is a cable generating noise between the piezo electric sensor and the rest of the project, in other words, you need to condition the signal. Eventually I empirically designed this (all comments are welcomed):
Finally you put everything in a 3D printed case, this was my 2015 Easter vacation project. On the router at the PC you get to see when someone passes the sensor.
And here are two screen shots for the case and the pillbox to protect the pressure sensor. All made in google sketchup which the best free CAD software there is in my opinion.