* experiment: computation of acceleration due to gravity. need photo transistor + laser. The phototransistor detects change of state. * The phototransistor breakout comes from elab peers.com. It works ...

* See the website elabpeers.com . the code comes from there. * http://www.elabpeers.com/ky-008-laser-x-laser-detector.html * you can use their laser + their ...