Motion detector is to detect intruders or damaging activity produces seismic signals to trigger an alarm detector. Vibration sensors are core components of the vibration detector. Vibration detectors are commonly used displacement sensors (mechanical type), speed sensors (electro-), accelerometer (piezoelectric), vibration detectors are basically surface-control detector.
Mechanical common mercury, heavy hammer type, ball type. When you directly or indirectly subject to mechanical shock and vibration, mercury beads, balls, hammer will leave the original based on the location of the alarm. Control range of the sensor sensitivity is low, small, suitable only for small scale control, such as doors and Windows, safety deposit box, part of the wall. Balls can be used for building, but only about 4m2, is rarely used.
General selection of electric speed sensor sensor from permanent magnets, coils, springs, dampers, and shell. This sensor with high sensitivity, detection range is large and stable, but high processing technology, the higher the price. Acceleration sensors are generally piezoelectric accelerometer, is the use of piezoelectric materials by mechanical deformation caused by vibrations in the charge, the size of the charge to determine the vibration amplitude, and take the circuit to adjust the sensitivity.
Vibration detector and detection surface securely, otherwise not easily felt vibrations, should stay away from vibration interference sources.