Electronic Projects

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  • Topic: Voltage regulator, Relay, Input/output
  • Pages : 19 (5307 words )
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  • Published : January 26, 2013
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Microcontroller Based Home Security A PROJECT REPORT ON “MICROCONTROLLER BASED HOME SECURITY SYSTEM” ABSTRACT

Engineering is not only a theoretical study but it is a implementation of all we study for creating something new and making things more easy and useful through practical study. It is an art which can be gained with systematic study, observation and practice. In the college curriculum we usually get the theoretical knowledge of industries, and a little bit of implementation knowledge that how it is works? But how can we prove our practical knowledge to increase the productivity or efficiency of the industry?

Don’t take the chance of becoming victim of burglary, which is often accompanied by violence. Protect our family and valuables with this microcontroller based security system that will let us rest our head knowing that should anyone trying to break into our home, an alarm will go off and the police will be alerted immediately. The transmitter section continuously transmits IR rays which are received by the receiver section. The received signal is further amplified and given to the PLL section, where its frequency is locked to the transmitted frequency. When the IR signal is interrupted, the microcontroller starts working as per the program burnt into the EPROM and control the siren, telephone and cassette player via the respective relays.

CONTENTS: Chapter Chapter: 1. Introduction. Chapter: 2. Circuit description. Chapter: 3. Working of the circuit. Chapter: 4. Used Components. 4.1. Microcontroller (AT89C51) 4.2. NE555 IC. 4.3. MCT2E Optocouploer. 4.4. Regulator (7805, 7809). Chapter: 5. Other Important Used Components. 5.1. BC548 NPN Transistor. 5.2. Relay (12V, 200ohm). Chapter: 6. Applications Summery. Reference.

Chapter: 1 1. Introduction:
Protect our family and valuables with this microcontroller based security system knowing that should anyone trying to break into our home, an alarm will go ON and the police will be alerted immediately. The microcontroller based security system consists of transmitter, receiver, phase locked loop and processing section.

The transmitter section continuously transmits IR rays which are received by the receiver section. The received signal is further amplified and given to the PLL section, where its frequency is locked to the transmitted frequency. The transmitter and receiver are arranged such that the transmitted IR rays fall directly onto the phototransistor LI4GI of the receiver. The signal received by T2 is amplified by transistor T3 and operational amplifier µA741 (IC2). Series input resistor R8 and feedback resistor R9 determine the gain of op amplifier IC2. The amplified single so applied to pin 3 of PLLLM567 (IC3) through capacitor C4. ICLM567 is highly stable PLL with synchronous AM lock detection and power output circuitry it is primarily used as frequency decoder which drives a load whenever a sustained frequency falling within its detection band is present in its self biased input. The centre frequency of the determined by external components. In the absence of any input single, the center frequency of PLL’s eternal free running, current control oscillator is determined by resistor R12 abed capacitor C8.

Preset VR2 is used for tuning IC3 to the desired center frequency in the 6-10 kHz range, Which should match the modulating frequency of the transmitter? Capacitor C6 and C7 are used as low pass filter. Ned out filter respectively when the received signal is locked to frequency of transmitter signal pin 8 of IC3 goes low and LED 1 glows. Since pin 8 is connected to the base of transistor T4 through R13 its collector voltage rises. As a result T5 is forward biased to energies the relay RL5 the pole and normally closed contact of really contact of RL5 are connected to +5v.

When the IR signal is interrupted, the microcontroller starts working as per the program burnt into the EPROM and control the siren, telephone and cassette player via the...
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