Abstract: A self-contained acoustic beacon activated by a seawater switch for provig an independent method of locating and recovering a floating or submerged recoverable target. The device provides an ideal operating life for target recovery of about 36 hours as well as providing an extensive underwater range. The device also provides stable frequency operation without a crystal-controlled oscillator over a wide range of source voltages allowing use of inexpensive batteries as a voltage supply source. Additionally, the signature or output signal code of the device can be changed simply and quickly providing positive identification of the acoustic beacon and lengthened operating life span.

Abstract: An electronic matching circuit for use in teaching, having a plurality of contact pairs interconnected through an interchangeable and programmable matrix. One contact of each pair corresponds to a stimulus and the other contact of each pair to a response. A pair of decision probes are engaged with selected stimulus and selected response contacts. A momentary contact switch is depressed and one of two visual indicators is illuminated to display when a correct or incorrect response, respectively, has been chosen. Digital logic in conjunction with the decision probes determines which color indicator is energized.