Thermocouple signal error suppression - uses compensation circuit with transistor to compensate for variation on thermocouple reference junction

摘要

A compensation circuit is for use with a thermocouple pair transducer. It uses the temp. characteristics of a diode connected transistor to reduce the error in the thermocouple output arising from temp. variations at the reference junction. The thermocouple pair output is connected via a resistance (11) to a linear amplifier (12) which has a resistive (13, 14) feedback network incorporating a diode connected transistor (17) mounted near the reference junction (18) of the thermocouple pair. As the temp. of the reference junction changes, the conductance of the transistor (17) changes in the opposite sense to that of the junction (18) and the amplifier output (UA) is compensated accordingly.