B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
B06B1/0207—Driving circuits
B06B1/0215—Driving circuits for generating pulses, e.g. bursts of oscillations, envelopes