That old upright piano still sounds great, and now it can easily have its own special effects. [DangerousTim] added LED strips which change color when he tickles the ivories. The strips are applied ...

Fig. 1: Diagrams from Wente’s 1916 patent application show the condenser microphone in cutaway view. Diaphragm (#6), which is grounded, is stretched only 5/10000th of an inch from the backplate (#7), ...

Using a speaker as a microphone is a trick old enough to have become common knowledge, but how often do you see the hack reversed? As part of a larger project to measure the acoustic power of a ...