[Lindsay] has a wonderful writeup about a new toy in the shop, an ultrasonic transducer. The 28kHz, 70W bolt-clamped Langevin transducer by itself is not much use, you need a power supply ...

Description: Since the company was established in 1948, NDK has manufactured and sold synthetic crystals and various products using the crystal such as crystal units, crystal oscillators, crystal ...

Not so, if you use a pair of specialised ultrasonic transducer arrays to move the air instead! (Video, embedded below) Three banks of thrusters provide a 180 degree steerable net force Details are ...