Abstract: An output circuit providing isolation between inputs and the output employs first and second opto-couplers for isolation. Pulse activation of the first opto-coupler turns on an output transistor and pulse activation of the second opto-coupler turns off the output transistor. An input stage of the output circuit is and light emitting devices of the first and second opto-couplers are powered by a first power source and an output stage of the output circuit is powered from an external power source. Power consumption by the input stage of output circuit occurs only during pulse activation of the first and second opto-couplers.

Abstract: A system for enclosing an instrument, module or other assembly in an explosion-proof housing. The system includes an upper housing portion that includes a first threaded portion and, optionally, a transparent window portion; a lower housing portion that has a second threaded portion that is structured and arranged to cooperate with the first threaded portion to provide a tight, air- and water-tight fit; and an inner mounting assembly for supporting an instrument, module, electrical circuit, electrical device, display device, or other assembly. In pertinent part, the lower housing portion includes integrated bosses that provide horizontal surfaces for supporting the inner mounting assembly and for releasably attaching the inner mounting assembly to the lower housing portion.