Abstract: Security is primary concern for every one. This Project describes a design of effective security alarm system that can monitor an industry with eight different sensors. Unauthorized access, Fire accident, wall braking, IR detection, and fire detection can be monitored by the status of each individual sensor and is indicated with an LED. This LED shows whether the sensor has been activated and whether the wiring to the sensor is in order. Obviously, this burglar alarm also has an input to 'arm' the alarm, a tamper input and a couple of outputs to control a siren and Auto dialing system. The alarm is also fitted with a so-called 'panic button'.
The burglar alarm is built around the AT89C51 micro controller from Atmel. This micro controller provides all the functionality of the burglar alarm. It also takes care of filtering of the signals at the inputs. Only after an input has remained unchanged for 30 milliseconds, is this new signal level passed on for processing by the micro controller program. This time can be varied by adopting small changes in the source code.
A maximum of 8 sensors can be connected to the burglar alarm. A power supply voltage of +5 VDC is available for each sensor at the corresponding wiring terminals. Eight LEDs indicate the status of the corresponding sensors. When the alarm has been activated, the LED of the sensor that caused the alarm will light up, or flash in the event of a cable failure.