Abstract: A static power switching system utilizes a parallel LC resonant circuit which is energized from a unilateral electrical power source through a switch circuit beginning at the point of minimum voltage across the switch circuit. Current drive to the resonant circuit at the point of minimum voltage across the switching element is obtained by controlled switching of a power transistor switch circuit using a switch control circuit that detects the minimum point of a voltage swing across the switch circuit and generates a switch control signal pulse. The switch control signal pulse is adjustable in duration depending upon load requirements and is applied as base drive to the power transistor. Power take off is by coupling to the inductor of the resonant circuit through its magnetic field. The switching system is particularly adapted for use in induction heating apparatus.

Abstract: 1. In a torpedo detecting device of the class disclosed, the combination of n elongated hose-like member having a towing device secured to one end thereof whereby the member is adapted to be towed through a body of water, and means in said member and remote from said towing device for disconnecting said member at a predetermined point in closely spaced adjacency from the towing device comprising a helical coil of explosive fuse cord disposed only at said point and capable of sufficient explosive damage to sever the member substantially at said point, and a pair of electroresponsive detonators for firing said fuse cord, said detonators being disposed respectively in abutting relation to the ends of said cord.

Abstract: 1. In a torpedo detecting device of the class disclosed, the combination of plurality of hose-like sections, means for coupling the sections end to end to form a single streamer, said streamer including means for receiving and retaining air supplied under pressure thereto and a flutter valve for controlling the admission of the air thereinto, said flutter valve comprising a pair of axially aligned tubular members disposed to provide a chamber, and having axially aligned openings at the opposite ends thereof, a cylinder disposed therein to be movable between the openings in said chamber and in response to a predetermined difference in pressure on opposite sides thereof to shut off the air supplied to the streamer when the pressure differential between the air supplied under pressure thereto and the air under pressure therein exceeds a predetermined value.

Abstract: 1. A vessel detecting apparatus comprising means responsive to the time ving negative pressure signal produced by the passage of a vessel in proximity to the detecting apparatus for producing an electrical signal having a time varying amplitude correlative with the square root of pressure signal, means for integrating said electrical signal over the interval of the negative pressure signal duration, and utilization means responsive to the time integral of said electrical signal.

Abstract: 8.