Just FYI, Hall Effect sensors are pretty actually old school[1], simple sensors. The kind of thing that's easy to play with via an Arduino, for example[2]. [1]

Just FYI, Hall Effect sensors are pretty actually old school[1], simple sensors. The kind of thing that's easy to play with via an Arduino, for example[2]. [1] : http://en.wikipedia.org/wiki/Hall_effect http://en.wikipedia.org/wiki/Hall_effect [2] : http://playground.arduino.cc/Code/HallEffect http://playground.arduino.cc/Code/HallEffect