Temp. controller for tracking pilot temp. to average two temps. - has transducers in controlled space and pilot connected into bridge circuit for averaging to control heater

摘要

The regulator controls the temp. in a volume so that it linearly tracks the temp. of a pilot transducer (S1). The operating range is set by an adjustable potential divider (R3,P2) which provides reference input to a differential amplifier (A1) supplying the coil of an actuating relay (K). Two temp. transducers (S1,S2), having variable resistance vs temp. characteristics defined by the law R(t)=R(to) x (1+alpha(t-to))/ (1-(R(to)/R) alpha (t-to)) are connected as lower arms of a bridge circuit with fixed resistors (R1,R2) as the upper arms and a variable potentiometer (P1) connected between the two resistor-temp. transducer junctions. The bridge circuit averages the resistance variations between the pilot transducer (S1) and the controlled temp. transducer (S2) and applies a voltage proportional to the average to the variable input of the relay driver amplifier (A1) to regulate the temp. in the space monitored by the second transducer (S2). The regulator is used in refrigerators.