In order for the public's use of the toy music box to affect the projection/music, Adrian McEwan and I got an Arduino to act as a USB keyboard, sending key-presses to the laptop according to human interactions.
In this video, we test the Rotary Encoder. If you turn the knob, the Arduino sends a keypress (space bar) to the computer. If you stop turning, it send another keypress of 'space bar' to pause.
We had Spotify open anyway, listening to Kettel (electronic music for tinkering with electronics).
Night Sun was commissioned by Nottingham City Council for Light Night 2014, funded by Arts Council England. Find out more about the project at http://www.timetravelopps.co.uk/night-sun