Types of vibration sensor (Alarm)

1) Cheapest 10 cents sensor : a spring and a center wire type , this is for those cheap products like dollar worth bulgary / window alarm, wheel rotatatory led , ....
2) Piezo-electric couple with capacitor : Also cheap and for most cheap car vibration sensor alarm. VR sensitivity adjustable.
3) PIC controlled : with intelligent shock intensity and frequency counter, that a program will judge and avoid false alarm. VR sensitivity adjustable. However, mosre NC type (normally closed). Power consumption 11-17 mA.
4) Mercury 3D sensor... Good for slow angular movement.