THERMISTOR_BRIDGE

Published:2009/7/8 3:21:00 Author:May | From:SeekIC

Bridge is formed by thermistor with R1, R4, R5, and R6. Unbalance is sensed by CA3046 IC having two matched pairs of transistors, with additional output transistor in IC. Positive feedback through R7 prevents chatter as switching point is approached. R5 sets switching temperature precisely. Relay comes on when temperature drops below pre determined point; for opposite function, reverse positions of thermistor and R1. Value of R1 is chosen to give approximately the desired control point.-D. E. Waddington, Thermistor Controlled Thermostat, Wireless World, July 1976, p 36.



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