Laser harps seem to be catching on. This one is a work in progress and believe it or not there is no microcontroller or computer controlling the system. For more information have a look at the project page (translated version).
“This is my first video showing the sensor-circuit working, that contains 4 opamps (LM358) and only has a +5V supply (no negative supply). You can understand it’s a challenge to get it working! But it does work!“
