Burglar alarm circuits consist of

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RRB ALP Electronics Mechanic 21 Jan 2019 Official Paper (Shift 3)

Answer 1

Burglar Alarm

A burglar alarm is a security device that makes an alarming sound in case a person tries to gain forced or unauthorized entrance into a building.
It consists of infrared LED's.
A burglar alarm basically works on the principle of automatic conversion of energy from one form to the other due to variation in parameters such as motion.
The burglar alarm circuit typically converts electrical energy into sound energy upon sensing movement.
It detects the human body movement, whenever there is any body movement, the voltage at output pin changes.
It detects the change in heat, and produce output whenever such detection occurs.