Electric kettle automatic power off controller circuit diagram

The circuit working principle of this device is shown in the figure.

First, use epoxy resin to dip a sheet-shaped positive temperature coefficient switching thermistor RQ on the electric kettle. Connect the two ends of RQ to the ① and ② pins of LSE, insert the kettle into the power socket CZO, and press Power switch S. At this time, because the water temperature in the electric kettle is low and the resistance of RQ is small (<50K), the ④ pin of LSE outputs high level, the relay J immediately closes, the normally open contact j closes, and the power The kettle works with electricity. After releasing your hand, the relay J contact is self-protecting. Once the water boils (100°C), the resistance of RQ rises step by step, much greater than 50K, which is equivalent to the circuit disconnection of pins ① and ② of LSE. Therefore, pin ④ of LSE outputs low level, J is released, and its contact j is broken. Turning on completely cuts off the power of the electric kettle, allowing the owner to boil water without any worries when going out. Among them, RQ should use a switching thermistor with a positive temperature coefficient, and its Curie point is 100°C.