Abstract: An improved ultrasonic cleaning system employs a plurality of electroacoustic transducers located at different positions on the wall surfaces of a tank containing a cleaning liquid in combination with a source of electrical power and a selective switching system. The switching system applies the electrical power selectively, sequentially and intermittently to any specified one or more of said plurality of electroacoustic transducers to achieve substantially increased cavitation intensity levels in the cleaning liquid and thereby greatly improves the cleaning efficiency of the inventive system as compared to the conventional ultrasonic cleaners which are in widespread use.

Abstract: A deep-water low-frequency transducer employs a collapsible air chamber to equalize the internal transducer air pressure with the external hydrostatic pressure at the submerged operating depth. A capsule containing a highly pressurized gas is mounted inside the collapsible air chamber and an automatic valve mechanism releases the gas to inflate the collapsed air chamber at a predetermined depth, beyond which any further reduction in the air volume would impair the operation of the transducer. With the collapsed air chamber restored to its original full volume, the transducer will operate satisfactorily at increased water depths.

Abstract: An improved ultrasonic transducer designed for rugged outdoor applications uses a thin-walled cylindrical tube of polarized ceramic operating in the fundamental circumferential resonant frequency mode. The major portion of the external surface area of the vibrating cylinder is covered by a sound insulating barrier, thereby preventing sound radiation from the covered non-radiating surface area portion of the cylinder. Specific unique relationships between the diameter, length and wall thickness of the ceramic tube, which are necessary to achieve the objects of the invention, are described.

Abstract: A wide-range audio frequency underwater transducer is designed to make use of a massive small diameter vibratile piston driven by electromagnetic oscillatory forces to transmit omnidirectional uniform sound pressure level over the frequency range 100 Hz to 5 kHz. The rugged transducer design is adapted for low-cost mass production and can be used as a highly reliable expendable reference standard of source level for the calibration of in-situ stationary or moving sonar receiving systems. The magnitude of the source level can be accurately controlled by the magnitude of the electrical current supplied to the electrical winding over the entire frequency range of operation. A pressure equalization system is included in the design that permits use of the transducer at any depth down to 500 feet.