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Securiy is a matter of great concern to all of us in this
world. Normally there are four types of security threat to our property. 1
)Thief, an inturder. 2)Fire, so we use fire sensor. 3)Water spilage /over
flow, so we use water sensor. 4) Gas leak , we use gas sensor, whenever
there is security breach from one of above or any combination of above.
The project takes the following action 1) Sounds an ALARM to attract your
or public attention . 2) If the reset sw is not pressed within 30 seconds
the projects takes further action, 3) It makes an emergency call to
deliver an emergency message stored in speech IC. 4) It will make five
attempts to call you before it checks the conditions again. The project
presented here is based on world’ s most powerful intel’ s mcs-51
family of microcontroller atmel at89c51.
CIRCUIT EXPLANATION :
This project is based on 8051 microcontroller.(IC2) IC3 and is used
as buffer. IC4 is a one time programmable(otp) chip where messages
are stored. This is 21 second speech ic where total of 12 messages can be
recorded on eight different locations, but total duration should not be
more than 21 seconds. Recorded messages can be played back by setting the
trigger pin 10 & 11 to high, making these pin low will stop the
message, Setting these pin high will repeatedly replay the same message.
IC5 is an audio amplifire . Audio output from speech ic(IC4) pin no 7 cout
is coupled to this ic on pin no 3 through VR2 volume control and C10.
Amplified output from pin no 5 drives the speaker through capacitor C14.
R14 and C13 corrects the tone. .C15 and C16 couples the audio message to
telephone line. |