In the Touch sensitive burglar alarm circuit, M is the Touch plate. This can be used in places wherever touch sensitiveness is required.
When anybody touches the plate M, the signal goes to the trigger pin or second pin of IC 555. The IC gets triggered and it acts as a Monostable Multivibrator. With RP1, R2 and C4, it generates a pulse for a particular time. The clock pulse generation time is given by the formulae below the circuit itself. This pulse operates the IC2 – KD9561, which is a audio generator IC. The audio is then passed to the Loud speaker ‘B’ through the audio amplifier IC1. The recording voice and message can be changed and used accordingly as per the necessary of the user.
The circuit can be used in banks, lockers, garages and any security required areas.It can also be used mainly in automobile security. When anybody touches the vehicle, immediately the circuit gets activated and the alarm sounds.