The circuit is quite sensitive and it can detect very minor vibrations, which are produced during movement of things. For sensing vibrations we have used a peizo buzzer in the circuit, the sensitivity of the circuit can be adjusted with the 1M variable resistor. The transistor Q1 and Q2 is used to amplify the vibration signals received from the peizo sensor. The 555 IC is used to make a little time delay for the loud alarm siren. This time delay can be adjusted with the 2M variable resistor. The time delay also depends on the value of the 100uF capacitor, using a higher value capacitor will increase the time delay. For best performance attach the peizo part on the surface of the things to protect.
Note: This is not a touch-activated alarm and therefore it will not become activated when some one only touches the things on which it is placed, it only detects vibrations.
This multipurpose vibration sensing alarm can be used for many purposes for indoor and outdoor. In indoor it can be used on doors and windows to alert you with a loud alarm/siren when some unauthorized person is trying to open them and at outdoor you can use it with your bicycle and other things, which
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