Abstract: A switching power amplifier for use in low-frequency sonar applications. s amplifier comprises a set of four switching transistors arranged in a bridge configuration for switching a power source through a highly resonant, low-frequency, underwater transducer. The signal to be amplified is taken from a signal generator, filtered, converted to voltage logic levels, delayed and modified a predetermined amount in time to prevent a power short circuit through the bridge due to slow transistor switching, and applied to a set of four voltage transformers. A different voltage transformer is coupled to each of the switching transistors in the bridge circuit. These voltage transformers are coupled to switch their respective bridge transistors only when their primary currents are collapsing, thus effectively decoupling the bridge transistors and the power source from the signal conditioner and driver delay circuitry.

Abstract: Surface acoustic waves on a piezoelectric crystal substrate beat with the bulk shear wave energy generated by the incident surface wave and which pass through the thickness of the substrate to produce a beat signal which is collected and is useful in pulse systems.

Abstract: An improved ion-laser system utilizing a cold, perforated-wall hollow-cate electron-beam discharge to produce a high energy, high intensity self-collimated electron-beam to provide a high efficiency, high power continuous wave or pulsed ion-laser oscillations in both visible and ultra-violet ranges.