COLD WIRE THERMOMETER

摘要

A cold-wire thermometer measures a subject temperature irregularly varied with the lapse of time. The cold-wire thermometer includes: a constant voltage means; a bridge circuit; a sensor connected between the first output terminal and the ground; two variable resistors for serially connected between the second output terminal and the ground; a switch for adjusting a zero point of the first and second output terminals of the bridge circuit; a terminal(P) for measuring a response characteristic of the bridge circuit; a temperature sensor for generating a voltage being variable in response to the subject temperature irregularly varied; a current sensor for inputting a constant voltage from the constant voltage means, and sensing a current; a differential amplifier for amplifying a difference signal by inputting an output signal of the bridge circuit; overvoltage prevention means for preventing an overvoltage applied to the differential amplifier; and a second amplifier for amplifying an output voltage of the first amplifier. The method connects all ground points to one point, and minimizes a voltage drop.