FEEDDBACK TYPE TEMPERATURE COMPENSATION SYSTEM FOR CURRENTCONTROL TYPE VARIABLE RESISTANCE ELEMENT

摘要

PURPOSE:To enable a precise operation of temperature compensation throughout a wide range of operating current, by providing a constant resistance value at both ends of a compensating element, with an element of approximate temperature characteristic inserted in the feedback loop. CONSTITUTION:A compensated thermistor TH1 and an indirectly-heated thermistor TH3, the same element having an approximate temperature characteristic, are connected in series with the same operating current made flowing, simultaneously with a control current circuit for each of the thermistors connected to an AGC loop amplifying cirucit mu and a power circuit Vcc, and a change of resistance at both ends of the thermistor TH3 is applied to a feedback circuit beta of the AGC loop amplifying circuit mu. With a temperature changing in the compensated thermistor TH1 to cause a change of resistance at both ends of the thermistor, the same change is caused also in the thermistor TH3, and a control current is made changing so as to cancel the before said change by the AGC loop amplifier mu, thus holding a both end resistance RTH at constant of the compensated thermistor TH1.