The 555 Electric shock overvoltage circuit

Published:2011/7/18 5:28:00 Author:nelly | Keyword: Electric shock, overvoltage, security monitor | From:SeekIC

As shown on the figure 10-2, the security monitor includes a reduction voltage rectification circuit,a current transformer, a triggering circuit and a overvoltage protection circuit. The 555 is connected as the R-S trigger,when the body gets an electric shock and the current is greater than 15mA, the L1's actuated signal will make the 555 trigger flip and the three foot turns into the low power level. Then the SCR1 will not touch off, the J will release, the J1-1 and J1-2 will be disconnected, the power will be cut out through this way. The SCR2, D1, R2~R6, C4 make up the overvoltage protection circuit. When the voltage rises to 250V, the SCR2 will be turn-on,then the four foot will be low power level, the 555 will be forcibly reset and the J will be release, the power will be disconnected.



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