19-06-2014, 03:08 PM
MAHATMA JYOTI RAO PHOOLE UNIVERSITY
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DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
ABSTRACT
Laser home security alarms, which create beams of laser light, can be installed around your home’s exterior perimeter. If installed on your home's exterior, the alarms can be positioned at set intervals high enough above ground level to give your home's perimeter complete protecting from intruders by sounding an alarm when the beam of light is penetrated. Home security system is the best burglar deterrent you can have. Many people don't think about security at home until it is too late and they have become victims. The prime concern of this project is to provide total security. Here is a low cost, invisible laser circuit to protect your house from thieves or trespassers. A laser pointer torch, which is easily available in the market, can be used to operate this device.
The circuit provides a laser torch by 3V power-supply is used for generating a laser beam. A combination of plain mirrors is used to direct the laser beam around the house to form a net. The laser beam is directed to finally fall on an LDR. The laser beam should be aimed continuously on LDR. As long as laser beam falls on LDR, transistor remains forward biased and relay is thus in energized condition. When a person is crosses the line of laser beam, relay turns off and transformer gets energized. In this condition, laser beam will have no effect on LDR and the alarm will continue to operate as long as switch is on.
INTRODUCTION
Here is a low-cost, invisible to protect your house from thieves or trespassers. A laser pointer torch, which is easily available in the market, can be used to operate this device.
Advantages
• 78xx series ICs do not require additional components to provide a constant, regulated source of power, making them easy to use, as well as economical and efficient uses of space. Other voltage regulators may require additional components to set the output voltage level, or to assist in the regulation process. Some other designs (such as a switched-mode power supply) may need substantial engineering expertise to implement.
• 78xx series ICs have built-in protection against a circuit drawing too much power. They have protection against overheating and short-circuits, making them quite robust in most applications. In some cases, the current-limiting features of the 78xx devices can provide protection not only for the 78xx itself, but also for other parts of the circuit.
Disadvantages
• The input voltage must always be higher than the output voltage by some minimum amount (typically 2 volts). This can make these devices unsuitable for powering some devices from certain types of power sources (for example, powering a circuit that requires 5 volts using 6-volt batteries will not work using a 7805).
• As they are based on a linear regulator design, the input current required is always the same as the output current. As the input voltage must always be higher than the output voltage, this means that the total power (voltage multiplied by current) going into the 78xx will be more than the output power provided. The extra input power is dissipated as heat. This means both that for some applications an adequate heatsink must be provided, and also that a (often substantial) portion of the input power is wasted during the process, rendering them less efficient than some other types of power supplies. When the input voltage is significantly higher than the regulated output voltage (for example, powering a 7805 using a 24 volt power source), this inefficiency can be a significant issue
CONCLUSION
Using laser rays we can secure house from the thieves. Installing a burglar alarm at home ensures the safety of ones home and family, both of which are priced possessions. When an intruder attempts to break into anybody's home, the last thing they would want to be confronted with is a security system. Gone are the days when burglars robbed an empty house. Nowadays burglars can rob homes in broad daylight. There are a multitude of options available in the market today and that is what makes the selection of a security system tougher.