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ABSTRACT

The aim of home automation is to control home devices from a central control

point. In this paper, we present the design and implementation of a low cost but yetflexile and secure radio frequency based home automation system. The

communication between the remote and devices is wireless. RF transmission is

robust, reliable and can be used up to 100mtrs. It uses the RF transmitter/receiver

which operates a 434 Mhz and comprises of a pair of encoder/decoder. The

proposed work has been done experimentally and has been verified in real time.

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INTRODUCTION

Automation is todays fact, where more things are being completed every day

automatically, usually the basic tasks of turning on or off certain devices and

beyond, either remotely or in close proximity. The control of the devices when

completely taken over by the machines, the process of monitoring and reporting

becomes more important. There are clearly many benefits to home automation. The

first is greater comfort and convenience especially for old and disabled. A second

is improved safety and security. A third is a high level of control over operating

costs (e.g., energy conservation). The remote control technologies have been used

in the fields like factory automation, space exploration, in places where human

access is difficult. With the development of low cost electronic components home

automation migrated from being an industrial application to home automation. The

home automation, our point of concern deals with the control of home appliances.

In this project we introduced a low cost, flexible, wireless solution to the home

automation. The novel approach in this paper discusses the migration of the initial

control mechanism of devices with simple functionality. The basic aim of this

project is to control the electrical appliances through a remote control using RF

module. This RF module comprises of an RF Transmitter and an RF Receiver. The

transmitter/receiver (Tx/Rx) pair operates at a frequency of 434 MHz. An RF

transmitter receives serial data and transmits it wirelessly through RF through its

antenna. The transmitted data is received by an RF receiver operating at the same

frequency as that of the transmitter. The RF module is used along with a pair of

encoder/decoder. The encoder is used for encoding parallel data for transmission

feed while reception is decoded by a decoder. The Power Unit powers up the entire

circuit, it contains both AC and DC modes of power i.e. if one of them fails then

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the other one can compensate. A step down transformer which steps down 220V

AC to 12V AC.A bridge rectifier for conversion of an alternating current (AC)

input into direct current a (DC) output which provides full-wave rectification from

a two-wire AC input, resulting in lower cost and weight. The 7805 Voltage

regulator is used which stabilize the DC voltages used .The control unit controls all

the appliances and to reduce the cost of the whole system we have eliminated the

microcontroller and instead have used 4x16 Decoders, flip flops, Decimal counters

and transistors.

The most recent survey on smart homes was written by Chan and describes a

general overview of smart home research

1. Market researches claim that most of the homes will be equipped with home

automation systems in the very near future. According to market observers, the

home automation market in India is growing at a compound annual growth rate

(CAGR) of 30 per cent. This growth is mainly driven by the consumer's desire for

an up gradation of their lifestyle. By 2050, approximately 20% of the worlds

population will be at least 60 years old

2. According to the World Health Organization, 650 million people live with

disabilities around the world

3. This paper demonstrates how technology and products that have been developed

for the broad consumer market can provide great benefits for people who have

functional limitations by improving convenience, safety, security, quality of life

and independence.

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HOME AUTOMATION USING RF

Home automation is the use of one or more logic to control basic home functions

and features automatically. It includes the scheduling and automatic operation of

water sprinkling, heating and air conditioning, window coverings, security

systems, lighting, and food preparation appliances. Here, our emphasis is on

lighting using radio frequency. In this RF system the digital data is represented as

variation in amplitude of carrier wave. This modulation technique is known as

Amplitude Shift Keying (ASK). The basic system includes the transmitter and the

receiver. The transmitter contains the remote, power source, encoder IC, RF

transmitter and antenna.

The receiver contains the receiver, decoder, relay and the appliances which have to

be controlled . The complete system deployment diagram is shown in fig. 1.

Complete System Deployment Diagram

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WORKING

In this project we show that how we control electrical appliances with the help of

WIRELESS REMOTE(Radio Frequency Module).

As we press the switch from transmitter end then immediate data is to be

transmitting in the air. Data receive in air by the Radio frequency module and

proceed to the electrical appliances circuit.

In this project we use two circuits one is transmitter and second is receiver.

In the transmitter part we send the rf code by the transmitter by 4 switchs and in

the receiver we use four relay coil for electrical output.

As we want to switch on any electrical appliances we press the switch of the

transmitter.

As the switch is pressed, data is to be transmitting by the radio frequency

module.

In this project we use 433 Mhz modules for data transmission.

We use one encoder ic for data transmission.

All the switches are connected to the encoder. Encoder ic get the data from

the switch and transmit the data in serial by the RF transmitter.

In the receiver circuit we use RF module to get the data and decoded by the

decoder. Decoder deliver the data into 4 bit and we use further control circuit to

switch on/off.

This circuit utilizes theRF module(Tx/Rx) for making a wireless remote,

which could be used to drive an output from a distant place.

RF module, as the name suggests, uses radio frequency to send signals.

These signals are transmitted at a particular frequency and a baud rate.

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A receiver can receive these signals only if it is configured for that

frequency.

RECEIVER

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TRANSMITTER

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The input signals, at the transmitter side, are taken through four switcheswhile the outputs are monitored on a set of fourLEDscorresponding to each

input switch.

The outputs from the receiver can drive correspondingrelays connected to

any household appliance.

This radio frequency (RF) transmission system employs Amplitude Shift

Keying (ASK) with transmitter/receiver (Tx/Rx) pair operating at 434 MHz.

The transmitter module takes serial input and transmits these signals through

RF.

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The transmitted signals are received by the receiver module placed away

from the source of transmission.

The system allows one way communication between two nodes, namely,

transmission and reception.

In every card we use one encoder ic with digital data base, this digital data

base may be 16 bit or 32 bit. In this project we use 4 bit data base to show

the basic concept of this project Easily available encoder and decoders are

HT12 E and HT 12D. HT12 E is encoder ic and HT 12D is decoder ic We

use 18 pin version of encoder and decoder ic.

TheRF modulehas been used in conjunction with a set of four channel

encoder/decoder ICs. HereHT12E&HT12Dhave been used as encoder and

decoder respectively.

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COMPONENT ANALYSIS

Encoder (HT12E IC)

HT12E is an encoder integrated circuit of 212 series of encoders. They are paired

with 212 series of decoders for use in remote control system applications. It is

mainly used in interfacing RF circuits.

Application Diagram of HT12E encoder

The parallel signals generated at transmission end are first encoded (into serial

format) by HT12E and then transferred through RF transmitter (434 MHz) at a

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baud rate of around 1-10 kbps. It has a transmission enable pin which is active low

and begins a 4-word transmission cycle upon receipt of a transmission enable. This

cycle is repeated as long as TE is kept low. As soon as TE returns to high, the

encoder output completes its final cycle and then stops. It uses a low power and

high noise immunity CMOS technology whose operating voltage is 2.4~12 V. The

value of resistance R2 is 470 Kohm.

CONTROL UNIT

The control unit controls generates binary code by using transistors. It converts 16

decimal inputs into 4 bit binary data which is fed into the encoder IC.

TRANSMITTER & ANTENNA

The RF transmitter is an electronic device which, usually with the aid of an

antenna, propagates an electromagnetic signal

such as radio. The transmitter and receiver are tuned at same frequency. Data rates

are more than 10k bps and the output power up to 10dBm [6]. It performs a low

voltage operation down to 2.2V. It is shown in fig.4.

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The antenna transmits the signal in the ultra-high frequency range which is

received by the antenna of the receiver.

TRANSFORMER

A transformer is a static electromagnetic device that transfers an electrical

power from one circuit to another without change of frequency. It accomplishes

this by electromagnetic induction and where the circuits are in mutual inductive

influence of each other. A transformer consists of a core and two or more windings

coupled electromagnetically. There are primary windings and secondary

windings. The winding in which in which energy is delivered is known as the

primary winding while the winding to which energy is received is known as the

secondary winding. It is shown below.

An Ideal Transformer

WORKING PRINCIPLE OF A TRANSFORMER

A transformer works on the principle of mutual induction between two or

more inductively coupled coil .It consists of primary and secondary windings.When the primary winding is energized by sinusoidal voltage, an alternating

current flows in the primary winding. The alternating current so produced in the

primary winding set up an alternating magnetic flux in the core .The alternating

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flux link up the secondary winding thereby inducing e.m.f in the secondary

winding.

The type of transformer used in this project is a step-down transformer,

which steps the voltage from 220v to 12v.

BATTERY

An electric batteryis a device consisting of one or moreelectrochemical cells that

convert stored chemicalenergy into electrical energy. Each cell contains a positive

terminal, orcathode,and a negative terminal, oranode.Electrolytes allow ions to

move between the electrodes and terminals, which allows current to flow out of the

battery to perform work.

Primary (single-use or "disposable") batteries are used once and discarded; the

electrode materials are irreversibly changed during discharge. Common examples

are the alkaline battery used forflashlights and a multitude of portable

devices.Secondary (rechargeable batteries) can be discharged and recharged

multiple times; the original composition of the electrodes can be restored by

reverse current. Examples include the lead-acid batteries used in vehicles and

lithium ion batteries used for portable electronics. Batteries come in many shapes

and sizes, from miniature cells used to powerhearing aids and wristwatches to

battery banks the size of rooms that provide standby power fortelephone

exchanges and computerdata centers.

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WORKING PRINCIPLE OF A BATTERY

Batteries convert chemical energy directly to electrical energy. A battery consists

of some number of voltaic cells. Each cell consists of twohalf-cells connected inseries by a conductive electrolyte containing anions and cations. One half-cell

includes electrolyte and the negative electrode, the electrode to

whichanions (negatively charged ions) migrate; the other half-cell includes

electrolyte and the positive electrode electrode to whichcations (positively charged

ions) migrate.Redox reactions power the battery. Cations are reduced (electrons

are added) at the cathode during charging, while anions are oxidized (electrons are

removed) at the anode during discharge. The electrodes do not touch each other,

but are electrically connected by theelectrolyte. Some cells use different

electrolytes for each half-cell. A separator allows ions to flow between half-cells,

but prevents mixing of the electrolytes.

Each half-cell has an electromotive force (or emf), determined by its ability to

drive electric current from the interior to the exterior of the cell. The net emf of the

cell is the difference between the emfs of its half-cells. Thus, if the electrodes have

emfs and , then the net emf is ; in other words, the net emf is the

difference between thereduction potentials of thehalf-reactions.

The electrical driving force or across theterminals of a cell is known as

the terminal voltage (difference)and is measured involts.The terminal voltage of

a cell that is neither charging nor discharging is called theopen-circuit voltage and

equals the emf of the cell. Because of internal resistance,[14]the terminal voltage of

a cell that is discharging is smaller in magnitude than the open-circuit voltage and

the terminal voltage of a cell that is charging exceeds the open-circuit voltage. An

ideal cell has negligible internal resistance, so it would maintain a constant

terminal voltage of until exhausted, then dropping to zero. If such a cell

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maintained 1.5 volts and stored a charge of onecoulomb then on complete

discharge it would perform 1.5joules of work. In actual cells, the internal

resistance increases under discharge and the open circuit voltage also decreases

under discharge. If the voltage and resistance are plotted against time, the resulting

graphs typically are a curve; the shape of the curve varies according to the

chemistry and internal arrangement employed.

Symbol of battery

RECEIVER

The Receiver Box will be fitted into the normal switch board of the room and we

can configure the line connections as fully automated or semi-automated. The

Receiver Box will get the signals from the remote control. It will then decode the

serial signal into 4 bit binary data. The binary data will be then converted into

equivalent decimal form. With the help of this decimal system we can operate up

to 24 or 16 electrical appliances in a room. The addressing can also be done on the

decoder chip to increase the number of rooms to 256. The Receiver Box also has

an uninterruptible power system so that incase power fails the conditions of the

respective appliances remains same i.e. the appliances which were ON remains ON

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and the appliances which were OFF remains OFF. The RF receiver is shown in

fig.. and its application diagram is shown in fig.9.

Fig.. RF Receiver

DECODER (HT12D IC)

HT12D Decoder is used to decode the RF Signal. They are 212 decoders are a

series of CMOS LSIs for remote control system. application which are paired with

212 series of encoder. For proper operation, a pair of encoder/decoder with the

same number of addresses and data format should be chosen. The Operatingvoltage is 2.4V~12V.

They interpret the first N bits of code period as addresses and the last 12-N bits as

data, where N is the address code number. A signal on the DIN pin activates the

oscillator which in turn decodes the incoming address and data. The decoders will

then check the received address three times continuously. If the received address

codes all match the contents of the decoders local address, the 12-N bits of data

are decoded to activate the output pins and the VT pin is set high to indicate a valid

transmission. This will last unless the address code is incorrect or no signal is

received.The output of the VT pin is high only when the transmission is valid.

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Otherwise it is always low. The application diagram is shown in fig.. The value of

resistance R3 is 33 Kohm.

CONTROL UNIT

It uses 4x16 Decoders, flip flops, Decimal counters and transistors [9]. The 24 pin

7474 IC is used as a 4X16 Decoder. It 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 demultiplexing function is performed by using the

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

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with the other strobe input low. When either strobe input is high, all outputs are

high. Its connection Diagram is shown in fig..

Toggle switch d flip flop using CD 4013 is used to toggle a relay or other load with

a momentary push button. Several push buttons can be wired in parallel to control

the relay from multiple locations. The only time a significant current flows - is

while the output pins are in the process of changing state. The outputs are -

"complementary". When the transistor switches on - it connects the negative side

of the relay coil to ground. And this causes the relay to energize. The transistor

does a second job. It connects the negative side of the LED (light emitting diode)

to ground which acts as an indicator. .

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RELAYS

The appliances are connected to the relay unit. It isolates AC from DC and also

provides switching of AC from DC.

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ADVANTAGES

ADVANTAGES

Ease of operability to the owner

Low cost

High level of security

Savings of the energy bills

Less consumption of time

Save life during fire

Highly efficient and flexible

Reliable

Provide comfort to elderly and disabled

All in one user-friendly system

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APPLICATIONS

Burglar Alarm, Smoke Alarm, Fire Alarm, Car Alarm, Security System

Garage Door and Car Door Controllers

Cordless telephone

Other Remote Control System

Wireless security systems

Car Alarm systems

Remote controls.

Sensor reporting

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CONCLUSION & FUTURE SCOPE

An automated home is convenient and cost-efficient. It saves time and money as it

is pre-programmed to automatically do daily routine events. By combining all the

types of work which are being done individually by home automation, the work

becomes more flexible in order that all the work is done at once. In this paper we

introduced a low cost, flexible, wireless solution to the home automation. The

novel approach in this paper discusses the migration of the initial control

mechanism of devices with simple functionality using radio frequency.Home

automation has wide scope in the future.

Future homes will be able to offer almost all required services

e.g., communication, medical, energy, utility, entertainment, and security. With

microprocessor control however, home climate control systems can be

programmed to meet precise preferences related to the time of day or the day of the

week. Today, home automation is no longer a futuristic fantasy and just confined

to the affluent class but a reality that is being associated with mainstream design as

well and is slowly becoming a part of everyday life. Home owners from different

social strata have begun seriously contemplating the adoption of technology to

ensure comfort, convenience and personal security. According to market observers,

the home automation market in India is growing at a compound annual growth rate

(CAGR) of 30 per cent. This growth is mainly driven by the consumer's desire for

an up gradation of their lifestyle.

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[2] (2008, Dec. 1).Available: http://www.un.org/News/Press/

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[3] (2009, Jun. 23) http://www.who.int/disabilities/en/

[4] Simon Haykin, Digital Communications, Wiley, 1988

[5] Gao Wenhuan, Liu Runsheng, Basic knowledge of Electric Circuit. Higher

Education Press. Beijing, 1996.

[6] Melly, T.; Porret, A.-S.; Enz, C.C.; Vittoz, E.A., An ultralow-power UHF

transceiver integrated in a standard digital CMOS process: transmitter, Solid-State

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[7] W. Yao and Y. E. Wang "Ultra-wide band pulse transmitting through resonant

antennas",Int. J. Opt. Wireless Commun., 2006

[8] C. W. Solomon "Switched-capacitor filters: precise, compact, inexpensive",

IEEE Spectrum, vol. 25, pp.28 1988

[9] Adel S. Sedra, Kenneth C. Smith, Arun N. Chardorkai Microelectronics

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[10] B.G. Streetman and S. Banerjee, Solid state electronics devices, 5th Edition,

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