Locker Security System

The project locker security system is aimed at protecting the offering box from robbery. The project is based on micro-controller AT89C51 and some associated components. The major advantage of this security system other than the available security system is that this sounds and alarm and calls to a predefined mobile number when an attempt of robbery is detected.

The mobile number can be of any persons managing the offering box and there is an option for a second mobile number to which the controller makes a second call at the time of robbery. The second mobile number can be the number of police station, so police will get notified and they can do the necessary actions immediately.  

As soon as the mobile calling section is finished by the controller it will generate an alarm. This alarm can only be disabled by using a secure password. So this security system has 3 levels of protection, password protection, call to predefined mobile number and an alarm.

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The heart of the circuit is the micro-controller AT89c51.

The power supply unit supplies regulated 5volt to the controller using lm7805. The transformer steps down the ac voltage to 12volt and rectifier diodes are used to convert 12volt ac to 12volt DC. This 12volt DC is then regulated to 5volt using LM7805.

 The controller on power up initializes the whole system. There is a power on reset circuit connected to the reset pin of the controller. So whenever power is switched on the controller resets.

 As per the program logic the controller first configures the LCD for displaying initializing data on the screen. Then the controller goes for controlling and monitoring other hardware peripherals.

A keypad is connected to the circuit for entering the password. The controller then checks this password correct or not. If it’s correct code the controller then actuates the relay for opening the door. When the controller opens the door it disables the tampering circuit sensors for eliminating false triggering. For closing the door a door close key is provided. When the door is closed the controller immediately enables the tamper circuitry.

If a wrong password is entered more than 3 times the controller calls to the predefined number and sounds an alarm.

The tamper is detected using a special custom made vibration sensor which works on Newton’s 3^rd law of motion. The vibration sensors give an interrupt to the controller to indicate a tamper.

The LCD display displays the name of the security system and gives direction to the user to enter password and also notifies the user if the password is wrong and also gives indication about the calls during tamper.

The door of the offering box is made using an electronic sliding mechanism. On entering the correct password the correct password the controller actuates relay1 and relay 2. The relay outputs are connected to the motor of the sliding door mechanism. To open the door the motor is given a polarity at which it rotates in clockwise direction and to close the door the polarity of the motor is reversed.

The crystal used is 12 MHz; this gives clock to the micro-controller.

Transistor logic is used to actuate switches on the mobile phone for making calls. The transistor BC-547 is used as a switch mode. When the controller gives negative to the respective transistor base that transistor gets switched on and the corresponding key on the mobile phone is actuated.

 A backup battery is provided to work when power loss occurs. So this will ensure the proper working of the circuit in all conditions.

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