Circuit principle of temperature limit controller with warming sound report

As shown in the figure, step-down rectification, voltage regulator circuit transformer T, full-bridge rectifier QU, C1 and three-terminal regulator 7812, C2, etc., voltage regulator +12V voltage.
IC12 (1/4LM884) and R1, R2, RP1 and temperature measuring resistor RT form a temperature detection bridge comparator. RT is a negative temperature coefficient thermistor that decreases linearly with increasing environmental conditions. The IC12 (1/4LM884) op amp is connected to a voltage follower.

Temperature limit controller circuit with warming audio report



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