RANDOM ON/OFF OF LAMPS TO DETECT BURGLARS FOR LOCKED HOUSES

Model no.7A:

            Random ON/OFF time in periodical intervals is generated by the programmed microcontroller which is fed to a pair of opto isolators to trigger the TRIAC used in series with the load. The lamp load thus switches ON and OFF randomly through the night indicating a situation of somebody’s presence in the house to detect burglars. As frequent ON/OFF of the lamp might reduce the life of the same, we have incorporated a Zero Voltage Switching such that the lamp always switches on at the zero cross of the supply waveform. The project is having comparator which is used for ZVS output. The ZVS (ZERO VOLTAGE START) is given as reference interrupt to microcontroller. The microcontroller is of 8051 family which is of 8bit. In this we are using push button as switch which is used as reference interrupt to microcontroller and using that interrupt we give signal to opto-isolator. The opto-isolator used in the project is used as switching element using this we will trigger the TRIAC. On the base of TRIAC triggering the AC lamp can be controlled to ON at low voltage. This will increase the life of the lamp. The power supply consists of a step down transformer 230/12V, which steps down the voltage to 12V AC. This is converted to DC using a Bridge rectifier. The ripples are removed using a capacitive filter and it is then regulated to +5V using a voltage regulator 7805 which is required for the operation of the microcontroller and other components.

For more details about this project, please visit   http://www.efxkits.com/project-kit/microcontroller/1065.html

HARDWARE REQUIREMENTS:

Microcontroller (AT89C52/S52), LM358, Opto Isolators, TRIAC, Transformer, Diodes, voltage regulator, push button, LED, Resistors, Capacitors, Crystal oscillator, lamp.

SOFTWARE REQUIREMENTS:

Keil compiler, Languages: Embedded C or Assembly

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