555 automatic home appliance protector circuit

Published:2011/6/1 2:32:00 Author:TaoXi | Keyword: 555, automatic, home appliance, protector | From:SeekIC

As the figure 15-8 shows, the protector is composed of the step-down rectifier circuit, the over-voltage under-voltage detection circuit and the delay switch control circuit. This circuit has some points of features such as the large power control, over-voltage (250V) and under-voltage (170V) protection , and the 5 minutes power-off delay. The over-voltage under-voltage detection circuit is composed of the R2，R3，RP1，R4 and RP2, and the over-voltage under-voltage trigger circuit is composed of the over-voltage under-voltage detection circuit and the IC1(555). In the power supply voltage is normal, the IC1 outputs the rectangular wave, this wave is rectified by D9，D10, then establish the positive DC voltage on C5 to conduct the power switch integrated circuit IC2 (TWH8778), then the SCR is in the state of trigger conduction, the socket has the electricity.



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