555 household electron protector circuit

Published:2011/6/9 8:14:00 Author:nelly | Keyword: household electron, protector | From:SeekIC

As shown in the figure 10-16, 555 obtains VDD=+12V supply voltage from hypotension rectifier circuit. 555 is in reset state, J has no action, it transmit power normally. When it is over load, the hypotension produced by RP1 increases, VT1 is saturation conduction, 2 foot is low level(<1/3VDD), 555 is reset, J pulls in, the power supply is cut off. When the body gets an electric shock, the current of transformer T's L2, L3 is not equal, the magnetic flow produced by two coils can not be canceled out, the alternating voltage is induced by the both sides of L1, it is rectified by D3, then VT1 is saturation conduction, 555 is reset, J pulls in, the AC power supply is cut off.



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