TEMPERATURE CONTROL CIRCUIT

摘要

PURPOSE:To facilitate the easy active or stop control by setting desired levels for resistance values of resistances which decide the upper and lower limit temperatures for load control. CONSTITUTION:The emitter of the 1st transistor (TR) 10 serving as a switching means is grounded via a detection element 11 which varies the resistance value by temperatures. While the mitters of the 2nd and 3rd TR12 and TR14 are grounded via resistances 13 and 15 which decide the upper and lower limits of temperature respectively. The collectors of those TRs are connected to a constant voltage power supply VDD via a resistance 16. A microcomputer 18 contains a pulse generating circuit which designates the digits of a display part 20. Thus the pulses are delivered to the bases of TRs 10-14 to turn them on alternately. As a result, the divided voltage obtained in an ON mode of each TR is stored to the 1st-3rd registers 23-25 via an A/D converter 17 to undergo comparison and operation. Thus the start/stop of a load 19 is controlled.