Home Automation using Digital Control

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Home Automation using Digital Control

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ABSTRACT:

Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of

appliances through telephone lines. It can be used to switch appliances

from any distance, overcoming the limited range of infrared and radio

remote controls.

The circuit can be used to switch up to nine appliances (corresponding to

the digits 1 through 9 of the telephone key-pad). The DTMF signals on

telephone instrument are used as control signals.

The digit ‘0’ in dtmf mode is used to toggle between the appliance mode

and normal telephone operation mode. Thus the telephone can be used to

switch on or switch off the appliances also while being used for normal

conversation











Block Diagram:











Hardware Requirements:

POWER SUPPLY BLOCK

555 TIMER

RELAY

MT8870 DTMF DECODER

CD4049 INVERTER

CD4013 FLIP FLOP

MCT2E OPTO-ISOLATOR

74LS154

BC547

NPN TRANSISTOR











Power Supply:

230 V AC

50 Hz

Bridge rectifier

Filter(470µf)

5v Regulator

5V DC

12V step down

transformer











555 TIMER

The 555 Has Three Operating Modes:

Monostable mode:

In this mode, the 555 functions as a "one-shot". Applications include

timers, missing pulse detection, switches, touch switches, frequency

divider, capacitance measurement, pulse-width modulation (PWM) etc.









http://en.wikipedia.org/wiki/File:Signetics_NE555N.JPG

http://en.wikipedia.org/wiki/File:Signetics_NE555N.JPG



Astable:

The 555 can operate as an oscillator. Uses include LED and lamp

flashers, pulse generation, logic clocks, tone generation, security

alarms, pulse position modulation, etc.

Bistable mode or Schmitt trigger:

The 555 can operate as a flip-flop, if the DIS pin is not connected and

no capacitor is used. Uses include bounce free latched switches, etc.











CD4049-Inverter:

The CD4049 devices are inverting hex buffers, and feature logic level

conversion using only one supply voltage (VCC)

These devices are intended for use as CMOS to DTL/TTL converters

and can drive directly two DTL/TTL loads











DTMF Decoder:

This circuit detects the dial tone from a telephone line and decodes the

keypad pressed on the remote telephone.

Two distinct frequency tones make up the DTMF(dual tome multiple

frequency), and hence the name.

The dialer and the telephone exchange communicate one way through

the DTMF communication.

The tone generator and the tone decoder consist of a complete

communication setup.

In this project, IC MT8870DE is used to decode the input dial tone to

the dialed numbers.











These digital bits are interfaced to a microcontroller for any

application.

Pulse/dial tone method is used in the modern telephone

communication.

There is a dial tone generator on the caller side and a unique tone

consisting of two audible tone frequency is generated when the user

presses a button.

As an example, 697hz & 1209hz will be generated when key '1' is

being pressed on the phone.

A decoder circuit is present on the receiver side, which decodes the

tone to a digital code.











CD4013 Flip Flop:

The CD4013B dual D-type flip-flop is a

monolithic complementary MOS (CMOS)

integrated circuit has two D-type flip-flops,

which you can use independently

A D-type flip-flop, also called a D-type bistable,

is a subsystem with two stable states. Using

appropriate input signals, you can trigger the flip-

flop from one state to the other.











OPTO-Isolator:

Opto coupler is a 6 pin IC.

It is a combination of 1 LED and a transistor.

when light falls on the Base-Emitter junction then it switches pin5

goes to zero.

When logic zero is given as input then the light doesn’t fall on

transistor so it doesn’t conduct which gives logic zero as output.

When logic 1 is given as input then light falls on transistor so that it

conducts, that makes transistor switched ON and it forms short circuit

this makes the output is logic zero as collector of transistor is

connected to ground.











OPTO-Isolator:











BC547:

The BC547 transistor is an NPN Epitaxial

Silicon Transistor.

The BC547 transistor is a general-purpose

transistor in small plastic packages.

It is used in general-purpose switching and

amplification BC847/BC547 series 45 V, 100

mA NPN general-purpose transistors.

Whenever base is high, then current starts

flowing through base and emitter and after that

only current will pass from collector to emitter











74LS154:

Each of these 4-line-to-16-line decoders utilizes TTL circuitry to

decode four binary-coded inputs into one of sixteen mutually exclusive

outputs when both the strobe inputs, G1 and G2, are LOW

The DE multiplexing function is performed by using the 4 input lines

to address the output line, passing data from one of the strobe inputs

with the other strobe input LOW. When either strobe input is HIGH, all

outputs are HIGH.

These DE multiplexers are ideally suited for implementing high-

performance memory decoders. All inputs are buffered and input

clamping diodes are provided to minimize transmission-line effects and

thereby simplify system design.











74LS154:











Circuit Diagram:











This system is designed to provide control of home appliances through

landline by dialing the designated number for the particular load.

Dialing can be done from the home phone or a call made to the home

number from outside. This system is designed without engaging a

programmable microcontroller but is based on digital logic using

DTMF technology (Dual Tone multiple frequency) which receives the

command from the landline phone to develop digital output.

This digital signal is further processed to actuate switching mechanism

through relay driver to turn on/off the loads/appliances. It can be used

to switch appliances from anywhere, overcoming the limited range of

other infrared and radio frequency type controls. This proposed system

gives a new direction to the development of home automation.

Circuit Explanation:











Advantages:

High sensitive

Works with any Cell phone from anywhere

Low cost and reliable circuit

Coverage distance up to 10 meter











Applications:

Home appliances control

Hotel lights/ fans Control

Shops and Showrooms appliances control

Industrial appliances











Conclusion:

The concept of this system can be extended in future by giving an

acknowledgement message to the user by system on the status of loads

by using GSM modem.

Home Automation using Digital Control Project is very helpful in

Home, Industrial,Hotels and Show rooms









http://www.edgefxkits.com/home-automation-using-digital-control










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Home Automation using Digital Control