Rca Inc.

James W Tuska

Anthony D Robbi

Apparatus for detecting and displaying a high, normal, or low condition of battery voltage or engine temperature in an automobile by energizing an H, a dash, or an L, respectively, on a 7-segment display device. A voltage representing the condition is compared with upper and lower threshold voltages in comparators. Outputs of the comparators are applied through inverting and noninverting transistors to specific segments of the display unit. An input voltage above the lower threshold energizes the middle horizontal segment which displays a dash representing a normal condition. An input voltage above the upper threshold energizes the vertical segments to complete the display of an H representing a high condition.

Three-condition display system

An improved circuit for measuring resistance, as for the resistance of a temperature sensor, wherein the resistance varies over a wide dynamic range. The circuit provides two switch means to charge two capacitors through the unknown resistance. A time interval means measures charging time for one or both capacitors. Since charging time is directly proportional to resistance, a value of resistance is computed for one or both charging times. Control means, responsive to the time interval means, is provided to sequentially operate one or both switch means, the control means including means for selecting that charging time which is as long as possible yet within the range of the time interval means, thereby obtaining a higher resolution measurement in the range of sensor resistance where resolution would otherwise be inadequate.

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Pennington, NJ, United States of America

James W Tuska