02-02-2013, 11:08 AM
A PROJECT REPORT ON MICROCONTROLLER BASED HOME SECURITY SYSTEM
1MICROCONTROLLER BASED HOME.pdf (Size: 1.7 MB / Downloads: 51)
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.
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.
Working of the Circuit:
The transmitting IR LED1 and phototransistor T2 of the receiver are fitted to the gate such the IR rays
emitted by the LED directly fall on the phototransistor.
The IR LED transmits a train of IR pulses. These pulses are received by the receiver and amplified by
IC2. Output pin 8 of the PLL (IC3) is low when the PLL network is locked to the transmitter frequency
and relay RL5 energies to make PA line of IC7 low.
When someone walks through the gate to enter your home, the transmitted signal is interrupted. Output
pin 8 of the PLL network goes high and relay RL5 de-energies to make PA0 line of IC7 high. Now the
microprocessor starts working as per the program loaded in the EPROM.
Relay RL4 energies to activate the siren. At the same time, relay RL3 energizes to emulate lifting the
telephone handset off the cradle to provide the dial tone. After a few seconds, relay RL2 energies to short
the redial button contacts. After the loaded number is dialed, it switches off relay RL2. Then relay RL1
turns on the audio player.
Here we have provided the same polarity-reversal detection facility so that the audio player turns on only
when polarity-reversal is detected.
The actual-size, double-size track lay-outs for solder and component sides of the PCB for the 8085
microprocessor-based home security system are shown in figs5 and figs6 , respectively, and their
component layout in fig.7.
Description:
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4Kbytes of
Flash programmable and erasable read only memory (PEROM). The devices manufactured using
Atmel’shigh-density nonvolatile memory technology and incompatible with the industry
standardMCS-51 instruction set and pin out. The on-chip Flash allows the program memory to
be reprogrammed in-system or by a conventional nonvolatile memory programmer. By
combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmen AT89C51 is a
powerful microcomputer which provides a highly-flexible and cost-effective solution to many
embedded control applications.
Summary:
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 t6he 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 pre
merely 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.