Accrochages

I bought a small FM radio at the local Dollarama for 1 CAD. It has a volume knob / switch and three buttons: reset (I dunno what this is but I guess it resets to the first channel on the FM band), scan (goes to the next available channel) and light (activates a small light).

I did a little experiment where I just replaced the sound output by a light-emitting diode (LED), resulting in a light-producing devide that generates light according to the sound of the radio. It adds a strange feel to the object. I suppose this strategy could be used in the street: one would wonder what activates the LED. And it's pretty cheap, the only problem in that respect being that it's battery-powered (requires two AAA batteries).