Battery cold junction thermocouple protection circuit

Published:2012/10/16 22:31:00 Author:Ecco | Keyword: Battery, cold junction , thermocouple protection | From:SeekIC

K thermocouple end is placed is insulation block, the thermocouple junction ambient temperature is continuously controlled by IN914 diode. The diode correct hermoelectromotive force generated on junction by feedback voltage. Then it is sent to the op amp by 1.5MΩ and 475Ω resistors. The thermocouple junction is pulled in zero ice water during calibration. Tuning 500Ω can make output be zero pressure; then the thermocouple is inserted in 250 ℃ furnace, tune range for output is 2.50V. In 9 ~ 250 ℃ range, the accuracy of K thermal couple is ± 3 ℃.



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