Normally closed contact burglar alarm circuit diagram

  
Circuit schematic shown in Figure 1.SCR, R1 and AN SCR trigger switch circuit composed; IC1, R2, VT1, VT2 and BL siren composed of analog circuits. Usually, AN oppression by ho
Normally closed contact burglar alarm circuit diagram - schematic

usehold appliances, making two normally closed contacts disconnect, SCR trigger signal without blocking, the alarm does not work. When home appliances were lifting, AN two contacts automatically closed, the trigger terminal SCR trigger signal via R1 obtained from the positive power supply, SCR conduction, IC1 power of work, output terminal siren signal by VT1, VT2 power zoom, push speaker loud alarm sound. In this case, even if the appliance back in place or destroy AN, can not stop the alarm sound. Only the owner to open the alarm installation and other people together and sometimes difficult to find the switch S, in order to disarm the alarm.




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