[Arao] wanted to measure the RPM of a spinning wheel using parts that he could scavenge from his junk box. A bit of thought led him to build a reflective sensor which can measure the spinning of a ...

[Fernando] sent in a tip about a pet project he’s been working on. It’s an interesting take on a 3D scanner. He used a stepper motor to rotate the object being scanned, and an Arduino for control, but ...