Burglar alarm bell

  
Circuit operation principle of the device shown in Fig. Shaped permanent magnet mounted on the door ZT activity, normally closed reed AG mounted on the door frame. Usually ZT c
Burglar alarm bell - schematic

lose to AG, so that the two contact pieces open within AG, at this time of 5S foot was high, the modules internal circuitry is turned off, bells DL does not work. Sleep night after the owner, if a person comes into the room, and will inevitably lead to ZT AG away, within two contacts reset AG collapsed, so 5S module pin goes low, the internal circuit opened, DL power of work, issued a loud alarm sound. Not the door is closed again, the alarm will not stop immediately, since delay action R2, C, the circuit will still work for some time stops automatically.




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