Construction

For our actual physical device, we'd envisaged a cowling made from the housing of an actual light switch which could sit over any existing switch. It would block physical access to the switch itself so that the position of the switch could only be altered by the servo which was controlled by the system.

Where we were originally going to have a second switch inside this housing (as an input to the system) it has now been replaced simply with the LDR. It is imporant we all use the same LDRs so our values are consistent.

We experiemented with possible attachment onto the servos we were using so it would be physically possible to flip the switch. We had a look through the components of Lego Mindstorm NXT kits, thinking we could possibly use the wheels but these proved to be too big. A bottle cap actually was the right sort of shape and size but it was difficult to attach it to the servo in a way that was solid and stable enough.

The image below on the right shows the protoype as viewed from the back - the side that would be sitting flush with the wall / the existing light switch. When the servo turns, it physically flips the switch, hence switching the light off or on. The front of the housing where normally a switch would sit was the right size for a larger LDR so aesthetically it looked neat and covered up the mechanism, making it a bit more mysterious.

Unfortunately there wasn't enough room to contain the Arduino as well but in any case we still have to have it plugged into the laptop so it can upload to Pachube so we willl need to have wires running out of the housing in any case. Potentially if we were to ever revisit and develop this, we could build a housing which could contain the Arduino and a power supply as well, wirelessly transmit data via bluetooth or WiFi.