Abstract: A circuit is provided for generating a voltage signal corresponding to a wiper position in a linear or circular potentiometer having an open wiper position or an open wiper angle, respectively. The voltage signal circuit includes provisions for determining when a wiper is in an open wiper position or angle region. When the circuit is used with a freely rotating circular potentiometer, the voltage signal may be used to determine wind direction. The circuit includes a voltage source coupled to a conducting element and a wiper. A pulling resistor driven by an operational amplifier is coupled to the wiper and voltage source to provide an identifiable voltage signal corresponding to the open wiper state during rotation through the open wiper angle region.

Abstract: A multiple angle and redundant visibility sensor includes a plurality of optical transmitter/receiver pairs, each pair cooperatively coupled so as to transmit and receive in conically controlled beams along a common optical axis such that each transmitter faces, and directs optical energy directly into, its receiver pair. The plurality of pairs are staggered in angular orientation with respect to each other, with a common volume of intersection through which the approximate center of each optical axis passes. Each transmitter propagates a substantially conical beam of light which passes through an aerosol media which causes molecular scattering of the light. A single transmitter outputs optical energy at any given time, and the receiver intercept the appropriate scattered energy at different scattering angles depending on the relative axial orientation with respect to the scattering volume and the incident radiation.