Ding for the circuit principle: care, vs SCR trigger grounded, it is in the off state. When someone leads A burglar broke, the SCR trigger end to give a trigger voltage is turn
ed on, the oscillator complementary VT1 and VT2 and the like of electrical work, issued a beep sound. Meanwhile strobe light emitting diode LED is also due to thyristor energized and winking, inform someone to steal. S to disarm the alarm switch.