The function of a sensor is to sense the change in
'state' of an object, space or any specified parameter. e.g. a Door sensor can sense the
movement of the door (from close to open), a PIR can detect the change in heat due to a
movement of a human being in it's sensing range etc. There are various types of sensors
available in the market that are based on different principles. All the sensors give their
output to a control unit which acts upon it and depending upon what the owner has
programmed for, will sound an alarm or dial a phone or switch on lights etc. Many times in
the low cost models, the sensor, the control unit as well as the alarm are built into a
single housing, however the advanced units have all these three components of a alarm
separate so that the owner can mix-n-match. The descriptions of various sensors are given
hereunder.
 Magnetic
Switch
Passive
Infra Red (PIR)
Pressure
Object
Sensing
Infrared
Ultrasonic
Motion
Glass
break - Acoustic
Glass
break - Vibration
Dual
Technology
Glass
Foil
Touch
Vibration
Micro
wave
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