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Wide-Range Temperature Sensors with High-Level Pulse Train OutputTwo types of temperature sensors have been developed for wide-range temperature applications. The two sensors measure temperature in the range of -190 to +200 C and utilize a thin-film platinum RTD (resistance temperature detector) as the temperature-sensing element. Other parts used in the fabrication of these sensors include NPO (negative-positive- zero) type ceramic capacitors for timing, thermally-stable film or wirewound resistors, and high-temperature circuit boards and solder. The first type of temperature sensor is a relaxation oscillator circuit using an SOI (silicon-on-insulator) operational amplifier as a comparator. The output is a pulse train with a period that is roughly proportional to the temperature being measured. The voltage level of the pulse train is high-level, for example 10 V. The high-level output makes the sensor less sensitive to noise or electromagnetic interference. The output can be read by a frequency or period meter and then converted into a temperature reading. The second type of temperature sensor is made up of various types of multivibrator circuits using an SOI type 555 timer and the passive components mentioned above. Three configurations have been developed that were based on the technique of charging and discharging a capacitor through a resistive element to create a train of pulses governed by the capacitor-resistor time constant. Both types of sensors, which operated successfully over the wide temperature range, have potential use in extreme temperature environments including jet engines and space exploration missions.
Document ID
Document Type
Other - NASA Tech Brief
Hammoud, Ahmad
(ASRC Aerospace Corp. United States)
Patterson, Richard L.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 24, 2013
Publication Date
July 1, 2009
Publication Information
Publication: NASA Tech Briefs, July 2009
Subject Category
Technology Utilization And Surface Transportation
Report/Patent Number
Distribution Limits
Public Use Permitted.

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NameType 20090027758.pdf STI

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IDRelationTitle20090027744Analytic PrimaryNASA Tech Briefs, July 2009