Abstract: An electrical noise reduction circuit which includes field-effect transiss and a photocoupler, for use in alternating current circuits in conjunction with an electro-mechanical relay. The circuit essentially reduces the function of the electro-mechanical relay to that of a safety block, the function of contact closing being taken over by the time-delayed semiconductor devices of the noise reduction circuit.

Abstract: An ac initiation system which uses three ac transmission signals interloc for safety by frequency, phase and power discrimination. The ac initiation system is pre-armed by the application of two ac signals having the proper phases, and activates a load when an ac power signal of the proper frequency and power level is applied.

Abstract: A dual output simultaneous firing circuit which provides a means for explng fuse wires with a simultaneity of 20 to 200 nanoseconds even though the breakdown voltages of the fuse safety gaps have a large disparity. A DC voltage charges high voltage capacitors. When the charge voltage reaches the lower breakdown voltage of one safety gap, that fuse explodes. A balancing transformer induces momentarily an equal voltage which adds to the existing voltage on the undischarged capacitor. The additional charge breaks down the other safety gap causing the other fuse to explode.

Abstract: A two-phase control system for sequential switching of a.c. power. An a.c. nput is split into two phases. The two phases are switched simultaneously or independently by a plurality of switches in sequence. The output from the switches is recombined to provide the original a.c. signal at a desired voltage level.