Five functions of the refrigerator protector circuit

PESD1CAN electrostatic protection SOT23-3 24V two-way

The protector is composed of a time base signal generator, a grid voltage monitoring circuit, a shaping circuit, an electric appliance control circuit, and a leakage alarm circuit. The time base signal generator is composed of IC1 (CD4060) and R1, R2, W1, C1 and the like. It generates 3 time signals of 5 minutes 40 seconds, 22 minutes 30 seconds and 12 hours. After the time signal is logically combined by IC2 (C043), the defrosting time control signal of 22 minutes and 30 seconds is output every 12 hours from the IC29 foot.
The grid voltage monitoring circuit is composed of IC3 (C033) and W2, W3, R5, R6, etc., where W2 and W3 are upper and lower limit preset potentiometers respectively. When the grid voltage changes within the range of 175~245V, IC36 and 8 pins are 0V, and no control signal is output. When the grid voltage is lower than 175V, IC36 pin outputs control signal} When the grid voltage is higher than 245V, IC38 pin outputs control signal.
The leakage alarm circuit is composed of BG7, D3, HTD, W4 and so on. When a leakage occurs, the leakage current is rectified by D3 to oscillate BG7, which drives the piezoelectric ceramic piece HTD to sound an alarm. The output signals of the above circuits are shaped by IC4 to make the relays pull in, and the circuit power is cut off accordingly.