We wager you haven’t you heard the latest from ultrasonics. Sorry. [Lindsay Wilson] is a Hackaday reader who wants to share his knowledge of transducer tuning to make tools. The bare unit he uses to ...

Quadcopter type drones can be flown indoors, but unless you have a lot of space, it usually just ends in a crash. The prospect of being hit in the face by the propellor blades, spinning at 10k RPM ...