Abstract: A smoke detector that is insensitive to moisture, such as for use in aircraft cargo bays and the like, is provided. The smoke detector includes a housing defining a chamber that is sealed from outside light sources yet is capable of receiving smoke. The smoke detector also includes a light source that is positioned inside the chamber and a detector for receiving diffusely scattered light within the chamber. Advantageously, the smoke detector also includes a moisture compensating device that reflects a substantially consistent percentage of light incident thereupon regardless of moisture on the surfaces thereof such that the operation of the light source can be reliably tested even in environments where moisture has condensed or otherwise collected on the walls of the housing.

Abstract: A solid state temperature compensated annunciator is disclosed. The solid state temperature compensated annunciator includes a pressure sensor for measuring a pressure of the fillant within a vessel and a temperature sensor for measuring the temperature of the fillant within the vessel. The solid state temperature compensated annunciator determines a pressure that the vessel would have if the vessel were filled with a predetermined amount of fillant, and compares the measured pressure to the determined pressure. If the measured pressure is below the determined pressure, a warning signal is issued.

Abstract: There is disclosed a capacitance transmitter that is ideally suited for use with a capacitance probe for level, pressure or proximity measurement in which the capacitance of the probe member responds to the sensed physical parameter. The transmitter has only two conductors which furnish the operational voltage and which transmit the output current signal.