Remote controlled home appliance project report

                                      ABSTRACT

The main aim of conducting this project is to control a maximum of eight electrical
appliances by just using a TV remote. Normal IR circuits can switch only one device. But
using this circuit, different devices can be controlled using same remote with different
switches. In this circuit, we interfaced 8 devices. These devices are switched using remote
keypad -1 to 8. AT89C2051 microcontroller is used to control the inputs and outputs. TSOP
1736 (infrared receiver) is used to receive the infrared signals from TV Remote. ULN2803
(High voltage, high current) buffer is used to drive relays. A working system will ultimately
be demonstrated to validate the design.

                                          CHAPTER 1
                                      INTRODUCTION

Infrared (IR) light is an electromagnetic radiation with a wavelength longer than that

of visible light, measured from the nominal edge of visible red light at 0.7 micrometers, and

extending conventionally to 300 micrometers. These radiations with a frequency below our

eyes sensitivity cannot be seen, but can only be felt by our skin temperature sensors. Infra-

Red is interesting, because it is easily generated and doesn't suffer electromagnetic

interference and so it is widely used in communication and control circuits. The adventure of

using lots of infra-red in TV/VCR remote controls helped engineers to work on innovative

projects like controlling home appliances using TV remotes etc.

A TV remote that follows RC5 Protocol is used here. Receiver in the circuit receives

pulsed IR rays from the remote and sends them to a microcontroller that plays the role of a

decoder. Decoded signal is thus received by relay driver IC’s whose output activates the

corresponding home appliance. Thus this circuit can control the ON/OFF process of eight

appliances.

One of the major advantages of this circuit is to control any appliances by just being

in our living room. A major disadvantage is that obstacles on the path of IR rays can block its

remote sensing capabilities.3.3 Working

Our project as mentioned earlier is aimed at controlling 8 home appliances using a

Philip’s TV remote or any remote supporting RC5 Protocol. It controls the on/off process of

the appliances interfaced to this circuit. The devices are operated using the keypads 1-8. It

performs the function of an IR transmitter which sends pulsed IR rays after modulating the

original signal with a carrier of 36 kHz frequency. These signals are received by TSOP 1736

which is our IR receiver. These are designed to receive signals of only 36 kHz. It senses the

received output and demodulates them. Therefore original signals are retrieved after

demodulation.

This is a simple type remote control by using RF communication without

microcontroller. In this project a remote has been designed for various home appliances like

television, fan, lights, etc. It gives lot of comfort to the user since we can operate it by staying

at one place. We can control any of the appliances by using this remote within the range of

400 foots. In this project consist of two sections, transmitter (remote) and receiver section.

Whenever we are pressing any key in the remote it generates the corresponding RF signals,

and these signals are received by the receiver unit. ASK transmitter and receiver is used as

transmitter and receiver. HT12E, HT12D encoders and decoders are used in this electronic

circuit. The block diagram of the whole circuit is given below.

In remote section consist of an encoder (HT 12E) and a ASK transmitter. The encoder

generates 8 bit address and 4bit data. We can set the address by using the DIP switch

connected in A0 to A7 (pin 1 to 8 ) encoder. If we set an address in the remote section, the

same address will be required in the receiver section. So always set same address in

transmitter and receiver. Whenever we press any key in the remote the encoder generates

corresponding 4bit data and send this data with 8bit address by using ASK transmitter. The

transmitting frequency is 433MHz. The transmitter output is up to 8mW at 433.92MHz with

a range of approximately 400 foot (open area) outdoors. Indoors, the range is approximately

200 foot.

At the receiver section ASK receiver is present. The receiver also operates at

433.92MHz, and has a sensitivity of 3uV. The ASK receiver operates from 4.5 to 5.5 volts9

DC, and has both linear and digital outputs. It receives the datas from the transmitter. Then

the decoder (HT 12D) decodes the date and it will enable the corresponding output pin (pin

10,11,12,13). Each output pins are connected to separate flip flops. The output of encoder

will change the state of the flip flop. So its output goes to set (high) from reset (low) state.

This change makes a high signal in the output of the flip flop. This output signal is not

capable to drive a relay directly. So we are using current driver, SL100 transistor act as the

current driver. The appliance is connected to 230V AC through the relay and the appliance

will start. The relay will be re-energized when the same switch is pressed in the remote. This

is because we are pressing the same switch in the remote control. The output of the decoder

again goes to high so this signal will again change the state of the flip flop. So, the relay gets

re-energized and the appliance goes to OFF state.

                                     

                                               CHAPTER 7
                         RESULT ANALYSIS & DISCUSSION

By designing this Project we can aware about the working of Remote Controlled

Home Appliances and we can advance this instrument at low cost by developing its

features with some components.

The main application of this circuit is that we can control any appliance by just being

in our living room. This is very much helpful for elderly people as well as for those who are

unable to walk either due to physical disabilities or due to accidents. This circuit enables us to

control appliances in the top floor also.

Another major use of our project is that we can turn off the operating devices all

together at one shot by just pressing the power button.

http://www.youtube.com/watch?v=ObipjGYg6KM

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