RAJARSHI RANANJAY SINH INSTITUTE OF MANAGEMENT AND TECHNOLOGY

AMETHI

(Affiliated to Gautam Buddh Technical University Lucknow)

( 2011 – 2012 )

“ HOME AUTOMATION CONTROL SYSTEM USING RF REMOTE CONTROL” Submitted in partial fulfillment of the requirement for the award of

Bachelor of Technology Degree

In

Electronics and Communication Engineering

From Rajarshi Rananjay Sinh Institute of Management and Technology, Amethi

(Affiliated to Gautam Buddh Technical University Lucknow)

Under the guidance of

Mr. Bhupesh Chandra kushwaha

Lecturer (ECE)

Submitted by

Shalok Singh

Ajay Maurya

LalAdityaVikramSingh

Siddharth Tripathi

ECE 4th Year

RAJARSHI RANANJAY SINH INSTITUTE OF MANAGEMENT AND TECHNOLOGY

AMETHI

(Affiliated to Gautam Buddh Technical University Lucknow)

( 2011 – 2012 )

CERTIFICATEThis is to certify that this Project Report

“HOME AUTOMATION CONTROL SYSTEM USING RF REMOTE CONTROL ”

Is a bonafide record of the work done by

Shalok Singh (0838331023),Lal Aditya Vikram Singh (0838331014),

Siddharth Tripathi(0838331025),Ajay Maurya(0838331402)

In partial fulfillment of requirement for the award of Bachelor of Technology degree in Electronics and Communication Engineering from Rajarshi Rananjay Sinh Institute of Management and Technology, Amethi.

Mr. Bhupesh Chandra Kushwaha

Lecturer

(ECE)

Mrs. Kirti Jain

HOD

(ECE)

ACKNOWLEDGEMENT

At the outset, we would like to take this opportunity to express our gratitude and thanks to various people for their help during the period we were preparing the project.

We deeply express our heartful thanks to Miss Neha Shabbir, Project guide and Lecturer of Electronics and Communication Engineering, for his valuable technical suggestions, much needed guidance and constant encouragement, without which this project would not have come into existence.

We would also like to thank our friends for their help in obtaining the documents related to the project.

We also acknowledge our respected Director for providing technical journals and reference materials in the library, which helped to make our project work accurate.

Shalok Singh (0838331023)

Siddharth Tripathi(0838331025)

LalAditya Vikram Singh(0838331014)

Ajay Maurya(0838331402)

CONTENTS

1. Chapter 1a. Overview

2. Chapter 2a. Introductionb. Block Diagramc. Circuit diagram

3. Chapter3Program used in Project

4. Chapter4a) Component Descriptionb) Scopec) Use of Projectd) Limitation

5. Chapter5a. Conclusionb. Bibliography

MOTIVATION AND PROPOSAL:

The simple is just to make life easier. We invented TV remote

controls so we didn't have to get out of the chair to change the channel.

Some people now own complex media systems that require the owner to

press 10 different buttons on 5 remotes just to watch Oprah.

Press one button on a remote control and have it dim the lights,

set the volume level, and start playing a movie and music which you

desire. Not have the sprinklers turn on if it just rained. Get emails sent to

you at work or on your cell phone if a motion detector or security system

is tripped while out of the house. Get emails sent to you with the caller

ID information of a call received at your house when out. Automatically

turn the lights on in the house when the garage door goes up and it's

after sundown. Automatically turn the front porch lights on 1/2 hour

before sundown every day (and automatically adjust for daylight

savings). Automatically close the garage doors every night.

Automatically turn on holiday lights at specific times (all at once). The

full list is limited to imagination and a family's lifestyle.

CHAPTER - 1

OVERVIEW

It is one of real time applications in industry now a days all electrical devices in Industry controlled by manually, But in industry so many electrical devices is there. To control all electrical devices we need lot of “ MAN POWER “ if manpower increases Maintenance cost also increases; this is one of the drawbacks of industry, So to avoid such type of drawback we should need some WIRELESS controlling systems, One of wireless communication system is RF (Radio frequency) communication system, it is very cheap and very easy to implement, That is why we have selected RF- COMM, This is not only used in industry but also used in Domestic Purpose as home appliances controlling using RF remote, some persons who are unable to walk to switch board such type of persons need this type of project and also Who are old persons, why because you can switch ON/OFF load with remote, without moving away from your place,

We can control all loads at a time from one place(control room) without connecting any physical wire between loads and control room, In this project we are using RF transmitter, RF receiver, 89c82 microcontroller, BT136 Triac and some discrete components, In this project we have two main sections one is

transmitter and Receiver let us explain about transmitter (TX) , TX contain one RF Tx , HT640 (encoder) and 8 ON/OFF switches, when we are press one switch, the data from switch taken by encoder(HT640) which is given to Tx , the Tx simple transmitter it at RF frequency range(433MHz),

At receiver side we are receiving data from Tx which is given to decoder (HT 648L) the decoder decodes the data which has received from RF receiver, the decoded data is given to MIC (89c52), Inside MIC there is a S/W Program according to that program, your 89c52 controls all electrical loads In this project there is no need any physical conductor between Tx and Rx.

In this project we should notes one think that is AC loads should not directly connected to microcontroller however AC may be entire into controller due to this your controller may be destroyed, To avoid such type of drawback we need some drivers, In this project we are using TRAIC as load controller (as a switch) so we need TRAIC drivers. We have so many Traic drivers one of them is MOC 3021 used as a Traic driver in between Microcontroller to AC loads,

CHAPTER – 2

INTRODUCTION -

In this project we have Seven Electrical loads (bulb, AC, motors, heaters, and power controlling systems) in that SIX on/off loads and ONE variable load (SPEED CONTROL or current controlling) in variable load we can vary the load up to 7 steps (either INC or DEC) and also you can control the current though load, In Industry we have different types of loads at different locations

We can control all loads at a time from one place(control room) without connecting any physical wire between loads and control room, In this project we are using RF transmitter, RF receiver, 89c82 microcontroller, BT136 Triac and some discrete components, In this project we have two main sections one is transmitter and Receiver let us explain about transmitter (TX) , TX contain one RF Tx , HT640 (encoder) and 8 ON/OFF switches, when we are press one switch,

the data from switch taken by encoder(HT640) which is given to Tx , the Tx simple transmitter it at RF frequency range(433MHz),

CIRCUIT DIAGRAM –

HT640 and HT648L 8 channel Encoder Decoder IC's for RF Modules

CHAPTER – 3

how to use the TWS-434 RF transmitter, and RWS-434 RF receiver with the BASIC Stamp -- for a quick & simple RF communications project

This article shows how to use the TWS-434 RF transmitter, and RWS-434 RF receiver with the BASIC Stamp -- for a quick & simple RF communications project.

Note: This is a simple project, and can easily be expanded to transmit temperature data, alarm status, remote control signals, and other information over wireless links between several BASIC Stamps. Once you have your BASIC Stamps communicating over this inexpensive wireless link, the possibilities are virtually endless.....!

Figure 1:  BS1-IC Pin Diagram.

The BS1-IC or BASIC Stamp I (Rev.B) was chosen for the transmitter circuit due to it's small size.  This version of the BASIC Stamp is also relatively inexpensive -- and dedicating it to our transmitter section keeps the overall project cost down. Figure 1 shows the BS1-IC pin descriptions for reference during the remainder of this article.

The TWS-434 & RWS-434 RF modules have become extremely

popular, and many visitors/customers have asked us to post a project showing how to use these inexpensive RF modules with the BASIC Stamp.

This article will help you get started, and provide the basic information you'll need to establish an effective RF communications network using the BASIC Stamp with the TWS/RWS RF modules.

Figure 2:  BS1-IC & TWS-434 Connections.

Connect Pin# 7 (P0) of the BS1-IC to the data-input pin of the TWS-434 RF transmitter module. Pin# 4 of the TWS-434 is the antenna connection, and requires only a 13-inch piece of insulated hobby wire for an effective antenna. For maximum range, use an antenna that matches the frequency of the transmitter, and provides a 50-ohm load for the transmitter output.  This provides maximum RF energy transfer, and will let you reach the maximum operating distance. Under favorable conditions -- the TWS-434 will work up to 400'.

This project works exceptionally well at 100'. We didn't bother to test

it further -- since previous tests have shown these RF modules operate at well over 300' with matching 50-ohm antennas.

Using the SEROUT command:

The SEROUT command is used to send data to the transmitter input at 2400 baud. Since the data sheet for the TWS-434 specifies a maximum data-rate of 3Kbps, 2400 baud works reliably without pushing the envelope, and faster baud-rates for this application aren't necessary.

The BS1 Code:

symbol dat = b2

symbol synch = b3

symbol junk = b4

synch = "A"

junk = 126

start:

pause 1000

for dat = 1 to 255

serout 0,N2400,(junk,synch,dat)

pause 50

next

serout 0,N2400,(junk,synch,0)

goto start

What's What:

The code has been kept very simple to help you understand a few details of making an effective wireless link. Three variables are initially setup to hold data to be transferred to the receiver.

dat holds the data we want the receiver to decode, and act on.

synch holds the synchronization byte we'll use to synchronize the transmitter and receiver.

junk holds a byte of data that helps us make sure the receiver oscillator is stable, and ready for the next two incoming data bytes.

Now -- here's how it works.  The junk byte is only for sending a data stream to the receiver as a warm-up byte. This starts up the receiver oscillator, and helps ensure the receivers oscillator circuit is ready for the next byte. This is kind of a crude way of doing this, but it's effective enough to help avoid missing data that follows the junk byte.

With RF wireless communications -- it's often easy to miss the first byte coming from the transmitter. When this happens, we run the risk of receiving junk characters, or missing the transmission completely. Since our code for the BS2 will effectively ignore the junk byte, it's not a problem if we miss the first byte of data coming from the transmitter.

The synch (synchronization byte), lets us use the ability of the BS2 SERIN command with the WAIT modifier, and helps to synchronize the transmitter/receiver.

Without using the WAIT modifier in the serial input routine, it's likely

that we'll simply receive garbage characters on occasion, or possibly with every transmission. Here's why....!

Suppose the data you expect to see is the number 15.  The number 15 will look like this when it arrives: 00001111.

Now suppose we miss the first few bits of data, and the incoming number looks like this 00000111.  This can definitely cause problems.  Using the BS2 SERIN command with the WAIT modifier lets us make sure we first receive the synchronization byte before we accept further incoming serial data. This is very useful, and helps to avoid receiving garbage characters.

The Receiver Code:

' RF test program

' This test program is for the RF receiver.

' The serial input routine waits until the

' letter "A" is received before processing

' further incoming serial data. This method

' allows us to synchronize the receiver to

' the transmitter, and avoid false receptions

SYNCH CON "A" 'Establish synchronization byte

BAUD CON 16780 'N2400 baud (MAX)

DAT VAR byte 'Data storage variable

DIRH = %11111111 'All outputs

START:

SERIN 0,BAUD,[WAIT(SYNCH),DAT]

OUTH = dat

GOTO START

The receiver code simply waits for the synch byte "A" to arrive before accepting the remaining data. Once the synch byte is received, the data we are looking for will be placed on the Stamp port pins P8 - P15 using the command OUTH = dat.

Program flow then returns to the serial input routine to wait for the next incoming serial data-stream.

Note: Using the SERIN wait modifier helps to synchronize the receiver to the transmitter data. Without the wait modifier, noise can cause the receiving Stamp to receive noise or junk characters. This is a simple example, but works well enough for this application. For larger data packets, you may want to explore using CRC of other methods to qualify the incoming data.

Figure 3 shows how to connect the BS2 to the RWS-434 receiver module.

Figure 3:  RWS-434 & BS2 Connections

The serial data stream flows from the digital output of the RWS-434 receiver module into the BASIC Stamp II I/O-pin P0.

The LED's:

Figure 4: Connecting LED's To The Stamp

Using LED's connected to the BS2 I/O-pins, we have an easy way to

see how the wireless link is performing. For range testing -- you can replace the LED's with a beeper, buzzer, or other device that can generate an audible signal you can hear at a distance.

A little experimentation with the various options available with the BS2 SERIN command can even make this setup work better, but this should be sufficient to help you get started using the TWS-434 & RWS-434 RF modules with the BASIC Stamp.

The HT640 Encoder ICs are series of CMOS LSIs for Remote Control system applications. They are capable of Encoding 18 bit of information which consists of N address bits and 18-N data bits. Each address/data input is externally trinary programmable if bonded out.

The HT648L ICs are series of CMOS LSIs for remote control system applications. This ICs are paired with each other. For proper operation a pair of encoder/decoder with the same number of address and data format should be selected. The Decoder receive the serial address and data from its corresponding decoder, transmitted by a carrier using an RF transmission medium and gives output to the output pins after processing the data.

Features

Encoder

24 PIN DIP Operating Voltage : 2.4V ~ 12V Low Power and High Noice Immunity CMOS

Technology Low Standby Current and Minimum

Transmission Word

Built-in Oscillator needs only 5% Resistor Easy Interface with and RF or an Infrared

transmission medium Miniml External Comonents

Decoder 

24 PIN DIP, Operating Voltage : 2.4V ~ 12.0V Low Power and High Noice Immunity, CMOS

Technology Low Stand by Current, Trinary address setting Capable of Decoding 18 bits of Information 8 ~ 12 Address Pins and 0 ~ 4 Data Pins Received Data are checked 2 times, Built in

Oscillator needs only 5% resistor VT goes high during a valid transmission Easy Interface with an RF of IR transmission

medium Minimal External Components

15Comm-Linking: The basics of RF

Communication.

When most of us start out with communication, we just cant

understand one word from another. Those definitions just take the

living heart out of you. Not to mention the complex maths with all

the weird symbols, which looks exactly like what we’d read when

we read a novel after finishing three bottles of vodka(Assuming, of

course, that you are awake that long). So to make things simple

to understand and leaving all the mathematics to the guys who

make the modules we are going to use, we give you this tutorial.

Let us step aside and think about HBO. When you turn on the TV

and switch your channel to HBO or star movies or a news

channel, what exactly do you think the TV understands by

channel? Channel to us simply means the number at which we

get HBO or news or what we desire to see. But to the TV that

number is actually a address to a particular frequency. You see

that black like that come to the back of your TV actually contains

all the channels at one time. So when you tell that TV, I want to

see HBO it actually allows the signal pertaining to HBO through to

the CRT while all the other signals are blocked out. This is the

same concept in the Radio.

When you tune to a particular frequency the radio is basically

playing only the music that is being transmitted on

one particular frequency. This method of transmission is known

as FREQUENCY DIVISION MULTIPLEXING. But if we have only

one frequency to work on and our data is in Digital format then we

can use another method of transmission known as Time division

Multiplexing. Now  in Time division multiplexing, we basically

allow a particular signal transmit at a single frequency for say x

no. of seconds. Then we allow a different signal transmission at

the same frequency for the same amount of time and the cycle

continues. This kind of transmission is much better for us hobbiest

because we are, almost all the time, using Digital Data and

we generally have only one frequency to transmit on, like

433MHz. Now to do this manually is a pain. We’d have to set up

like a dozen different kinds of circuits and ICs for this. But we

have a neat trick. There are ICs that does this thing for us and

they are called RF Encoder/Decoder ICs. Like the Holtek

HT640(Encoder) and HT648L(Decoder).

Let’s start with the HT640 Encoder first. The circuit diagram is

given below.

http://www.madhatcreations.com/wp-content/uploads/2011/09/HT640.gif

Now, the pin diagram descriptions:

1. D0-D7: 8-bit Data pins. you can use this as a parallel interface(like from a microcontroller) or use them as

individual switches(like for controlling 4 motors,

remember the “A Input 1″ and “B input 1″ using the

L293).

2. DOUT: The DOUT pin is the ‘Digital Output’ pin. This pin 3. is the pin from which the encoder outputs it’s encrypted 4. signal. It should be connected to the DIN/Data-In pin of

your TX module.

5. TE: The TE pin is the ‘Transmission Enable’ pin. when you have loaded all the data on your data pins and set the addresses on the address pins, you pull TE high to start the transmission. It can be either clock controlled or button controlled depending on your needs. 0.5s-1s seems to be enough of a pulse with for successful transmission.

6. OSC2-OSC1: These two pins are the internal oscillator pins. You need to connect a resistor between the two pins. The value of the Resistor HAS TO BE SAME FOR ALL RECEIVERS OF THE TRANSMITTER, otherwise information will become out of sync.

7. Vss: Self-explanatory.8. Pins A0-A9: The ‘A’ Pins are called the Address pins.

Imagine you are running multiple receiving devices on the HT648L Decoder IC. But the Remote control transmitter is only one HT640 Encoder IC. How do we make sure that we get only one receiver to respond and not all the receivers listening to the command. For that we have something called Addresses for each receiver. The concept is quite simple. The Binary 10-bit combination has to be same on both the transmitter and receiver for the data to be successfully transmitted. If not, then the receiver will receive the transmissions but because the addresses don’t match it will ignore the signal. so now if my receiver has the 10bit(A0-A9) address of say ’0001110001010′, then for my transmitter to transmit data to that receiver my transmitter must also have the adderss ’0001110001010′. This is awesome considering that I can control 210=1024, 1024 different receivers from just one transmitter and ON THE SAME FREQUENCY BAND(433MHz in my case).

9. Vdd: +ve 5V supply.

Now lets see the HT648L Decoder IC.

Here is the Pin Description:

1. D0-D7: Output pins of the data pins from the transmitter.2. VT: VT stands for ‘Valid Transmission’. When there is no

errors in the transmitted data, VT goes High.3. DIN: The DIN pin is the ‘Digital INput’ pin. This pin is the

pin from which the decoder gets input of it’s encrypted signal that the encoder transmitted. It should be connected to the DOUT/Data-OUT pin of your RX module.

4. OSC2-OSC1: These two pins are the internal oscillator pins. You need to connect a resistor between the two pins. The value of the Resistor HAS TO BE SAME FOR ALL RECEIVERS OF THE TRANSMITTER, otherwise information will become out of sync.

5. Vss: Self-explanatory.6. Pins A0-A9: The ‘A’ Pins are called the Address pins.

Imagine you are running multiple receiving devices on the HT648L Decoder IC. But the Remote control transmitter is only one HT640 Encoder IC. How do we make sure that we get only one receiver to respond and not all the receivers listening to the command. For that we have something called Addresses for each receiver. The concept is quite simple. The Binary 10-bit

combination has to be same on both the transmitter and receiver for the data to be successfully transmitted. If not, then the receiver will receive the transmissions but because the addresses don’t match it will ignore the signal. so now if my receiver has the 10bit(A0-A9) address of say ’0001110001010′, then for my transmitter to transmit data to that receiver my transmitter must also have the adderss ’0001110001010′. This is awesome considering that I can control 210=1024, 1024 different receivers from just one transmitter and ON THE SAME FREQUENCY BAND(433MHz in my case).

7. Vdd: +ve 5V supply.

8. BASIC ELECTRONICS COMPONENTS9.

10. Electronics can at first seem extremely complicated to understand and learn. One look at a circuit board with all those little blinky LED's and black chips and unidentifiable circle pointy things can make anyone quit before starting.

11. But actually electronics can be much simpler than you think. Learning electronics is more like learning a foreign language alphabet. At first glance it is all a bunch of squiggles. But actually each letter has its own pronounciation and its own rules of use. And certain combinations of letters in a certain order form a word of some meaning. And a combination of words forms a sentence. This is the same for a circuit board. Each tiny component, such as a resistor or capacitor or transistor, has special rules and abilities. Combining a few into a circuit can create interesting effects. Combine a bunch of unrelated circuits together and suddenly you have a robot. So your first step would just to be to learn and understand the smallest of the components. Once there you can learn about combining them. Just like learning a foreign alphabet, no?

12. Ok first a quick crash course in electron physics. All electronics is designed to manipulate a flow of electrons. Electrons have mass and volume so you can almost think of electrons in circuits as water flowing through plumbing. The analogy is amazingly helpful if you think about it. Also note, the more electrons you have in one place, the higher the voltage. The more

electrons moving together, the higher the current. The same as with water.

13.POWER Power is simply the energy required to do something. If you are moving a large amount of electrons, and moving them through something that is resistant of that movement, power is used. Power is voltage times current. Power is also voltage squared divided by resistance. P = I * V P = (V^2)/R

14. Ground and Source Source is the positive part of your circuit. The plus end of your battery would go here. Ground is the negative node of your circuit. When you design your circuit, imagine a flow of electrons coming from the source, and heading to the ground. A quick note, in reality electrons move from gound to source. The confusion has historical reasons I dont want to get in to. But just know this fact, and pretend electrons move from source to ground.

15. Now think of this as water. 16. Water flows down the easiest quickest path between

these two points. More resistance to flow, less will flow.

17.

RESISTORS These do exactly what they say. They resist the flow of electrons. These are necessary for several reasons: - they can control how much current goes down each wire - they can control power usage - they can control voltages (since current, resistance, and voltage are interrelated)

18. The last point is important as it is the basis of Ohm's law, V=IR. Voltage = Current x Resistance. For example, suppose you take a resistor and connect the two ends of a battery with it. You know that your battery is 9V (or whatever) and you know the resistor is 3Kohm (determined by the color stripes on the resistor), so 9V divided by 3Kohm is .003amps (3 milliamps). So why is this information useful? Well now that you know the current, you can determine other useful things such as power. P=IV. You will notice that if you increase resistance, you decrease current. If you decrease current, you decrease power use. Put a 1ohm resistor between the battery and it will get so hot it

could burn because of the power use. Use a 100Kohm resistor and almost no power at all will be used.

19. So about determining the value of a resistor, all resistors have the value labled on them. You will notice colored stripes on the resistor. Each stripe means a certain number. This has been explained a billion times online already so I won't, just google search 'resistor color tutorial.' Click for a quick resistor color code reference chart.

20.

CAPACITORS Now suppose you want to control how the current in your circuit changes (or not changes) over time. Now why would you? Well radio signals require very fast current changes. Robot motors cause current fluctuations in your circuit which you need to control. What do you do when batteries cannot supply current as fast as you circuit drains them? How do you prevent sudden current spikes that could fry your robot circuitry? The solution to this is capacitors.

Capacitors are somewhat complex in theory, but most people can get by on the basics which I will explain here. Capacitors are like electron storage banks. If your circuit is running low, it will deliver electrons to your

circuit. If your circuit is in excess (such as when your robot motors are turned off), it will store electrons. In our water analogy, think of this as a water tank with water always flowing in, but with drainage valves opening and closing. Since capacitors take time to charge, and time to discharge, they can also be used for timing circuits. Timing circuits can be used to generate signals such as PWM or be used to turn on/off motors in solar powered BEAM robots.

21. Quick note, some capacitors are polarized, meaning current can only flow one direction through them. If a capacitor has a lead that is longer than the other, assume the longer lead must always connect to positive.

22. How do capicitors charge over time? This Capacitor Charge Curve Chart should help. The discharge rate would be the direct inverse. Theoretically (as made obvious by the graph) a capacitor can never be fully charged or discharged, but in reality this is never the case.

23. So how can you use capacitors in your robot? 24. Power surge/drainage management. 25. The problem with using robot components that drain

a large amount of power is sometimes your battery

cannot handle the high drain rate. Motors and servos being perfect examples. This would cause a system wide voltage drop, often reseting your microcontroller, or at least causing it to not work properly. Just a side note, it is bad to use the same power source for both your control circuitry and your motors. So don't do it.

26. Or suppose your robot motors are not operating at it's full potential because the battery cannot supply enough current, the capacitor will make up for it. The solution is to place a large electrolytic capacitor between the source and ground of your power source. Get a capacitor that is rated at least twice the voltage you expect to go through it. Have it rated at 1uF-10uF for every amp required. For example, if your 20V motors will use 3 amps, use a 3uF-30uF 50V rated capacitor. Exactly how much will depend on how often you expect your motor to change speed and direction, as well as momentum of what you are actuating. Just note that if your capacitor is too large, it make take a long time to charge up when you first turn your robot on. If it is too small, it will drain of electrons and your circuit will be left with a deficit. It is also bad to allow a large capacitor to remain fully charged when you turn off your robot. Things could accidently short and fry, such as curious kitties that get too close. So use a simple power on LED in your motor circuit to drain the capacitor after your robot is turned off. If your capacitor is not rated properly for voltage, then can explode with smoke. Fortunately they do not overheat if given

excessive amounts of current. So just make sure your capacitor is rated higher than your highest expected.

27. Capacitors can also be used to prevent power spikes that could potentially fry circuitry. Next to any on/off switch or anything that that could affect power suddenly should have a capacitor across it.

28. Capacitors can eliminate switch bouncing. When you flip a mechanical switch, the switch actually bounces several times within a microsecond range. Normally this is too small of a time for anyone to care (or even notice), but note that a microcontroller can take hundreds of readings in a single microsecond. So if your robot was counting the number of times a switch is flipped, a single flip can count as dozens. So how do you stop this? Use a small ceramic capacitor! Just experiment until you find the power capacitance value.

29. Capacitors can improve efficiency and longevity of electric motors up to 100%. Place a small ceramic capacitor of like 10uF across the two leads of your motor. This works really well with el-cheap-o motors. Not much effect with high-end expensive motors however. These capacitors will also signficantly reduce EMI (Electro Magnetic Interference) and system noise too.

30.

DIODES Diodes are what you would use to ensure current flows

in only a single direction. A great water analogy to a diode is a dam. Water never flows up a damn. But the analogy goes even further. With diodes, there is always a voltage across it (typically .7V forward voltage). Meaning if you have a diode come after a 7.2V battery, the voltage would then be 6.5V. This is just like a dam in that the water level will always drop. Doesnt current already always flow in only a single direction? No. RC circuits, or circuits involving AC power, or circuits that are noisy (such as with motors), involve currents that changes directions. So why would you only want current to flow in a single direction? Many many reasons. But for a beginner, you need to protect your circuitry from noise. A microcontroller would fry if current went the wrong way. Motor drivers and MOSFETs would too. Diodes are also useful for dropping high voltages to a lower more usable voltage.

31. This below chart represents the current vs voltage curve typical of diodes. As you can see, the current passing through a diode changes non-linearly as voltage changes linearly.

32.

33. There is another special diode called a zener diode. With the water analogy, a zener diode is like a dam, but with a pump at the bottom pumping water back to the top. Zener diodes allow current to flow in reverse as well as forward. The forward voltage is still around .7V, but there is a different reverse voltage of around negative ~2.3V. You will probably never need to use a zener diode.

34.

POWER SUPPLY

INTRODUCTION TO POWER SUPPLY:

Power supply is an important part of operation of

the microcontroller. Microcontroller operates at +5V DC

and also for other IC’s and displays. A 220v ac to 12-0-

12v transformer is used and for rectification, two diodes

IN4007 are connected for rectification of the step down

ac supply. Filter capacitor of 1000uF is used. It is

regulated to +5V using a regulator 7805. 0.1uF capacitor

is used for filtration of high frequency noise. LED is

give3n for power on indication.

TRANSFORMER:

Definition:

The transformer is a static electro-magnetic device

that transforms one alternating voltage (current) into

another voltage (current). However, power remains the

some during the transformation. Transformers play a

major role in the transmission and distribution of ac

power.

Principle:

Transformer works on the principle of mutual

induction. A transformer consists of laminated magnetic

core forming the magnetic frame. Primary and secondary

coils are wound upon the two cores of the magnetic

frame, linked by the common magnetic flux. When an

alternating voltage is applied across the primary coil, a

current flows in the primary coil producing magnetic flux

in the transformer core. This flux induces voltage in

secondary coil.

Transformers are classified as:

Based on position of the windings with respect to core

i.e.

Core type transformer

(1) Shell type transformer

(a) Transformation ratio:

(1) Step up transformer

(2) Step down transformer

(a) Core & shell types: Transformer is simplest electrical

machine, which consists of windings on the

laminated magnetic core. There are two possibilities

of putting up the windings on the core.

(1) Winding encircle the core in the case of core type

transformer

(2) Cores encircle the windings on shell type

transformer.

(b) Step up and Step down: In these Voltage

transformation takes place according to whether the

Primary is high voltage coil or a low voltage coil.

(1) Lower to higher-> Step up

(2) Higher to lower-> Step down

LM7805C:

A variable regulated power supply, also called a

variable bench power supply, is one where you can

continuously adjust the output voltage to your

requirements. Varying the output of the power supply is

the recommended way to test a project after having

double checked parts placement against circuit drawings

and the parts placement guide.

This type of regulation is ideal for having a simple

variable bench power supply. Actually this is quite

important because one of the first projects a hobbyist

should undertake is the construction of a variable

regulated power supply. While a dedicated supply is

quite handy e.g. 5V or 12V, it's much handier to have a

variable supply on hand, especially for testing.

Most digital logic circuits and processors need a 5

volt power supply. To use these parts we need to build a

regulated 5 volt source. Usually you start with an

unregulated power To make a 5 volt power supply, we

use a LM7805 voltage regulator IC (Integrated Circuit).

The LM7805 is simple to use. You simply connect

the positive lead of your unregulated DC power supply

(anything from 9VDC to 24VDC) to the Input pin,

connect the negative lead to the Common pin and then

when you turn on the power, you get a 5 volt supply from

the Output pin.

CIRCUIT FEATURES

Brief description of operation: Gives out well

regulated +5V output, output current capability of

100 mA

Circuit protection: Built-in overheating protection

shuts down output when regulator IC gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage,

reliable operation

Availability of components: Easy to get, uses only

very common basic components

Design testing: Based on datasheet example circuit, I

have used this circuit successfully as part of many

electronics projects

Applications: Part of electronics devices, small

laboratory power supply

Power supply voltage: Unregulated DC 8-18V power

supply

Power supply current: Needed output current + 5

mA

Component costs: Few dollars for the electronics

components + the input transformer

Applications Burglar Alarm, Smoke Alarm, Fire

Alarm, Car Alarm, Security System Garage Door and Car Door Controllers Cordless telephone Other Remote Control System

Compatibility Compatible with RF Modules 433

MHz. Link :RF Modules (Tx + Rx Pair) 433 Mhz ASK

Controlled Devices

The following devices will be controlled by the microcontroller:

Fan

Light

Digital thermostat

Controlled Devices - Fan

Controlled Devices – Light

IMPACT ON HOME APPLIENCE&INDUSTRY:

This project will have a huge impact on academics and industry. With the help of

this project we have tried to depict the modern & global application of cell phone.

Mobile phone for home automation control can overcome these limitations and

provides the advantage of home applience control, working range as large as the

coverage area of the service provider, no interference with other controllers.

This project is very useful on the home usage of cell phone or DTMF controlled

home applience .The home applience are controlled by the cell phone .

The industry can find major application of this project in developing mobile

operated products as commercial projects.

ADVANTAGES:

1. This circuit helps in controlling the home appliances

from a remote place.

2. One circuit can control up to eight different

appliances directly and further the equipment can be

grouped using a multiplexer, several other devices

can be controlled. Cost involved for making and

operating the circuit is

minimum.

3. Low power requirement and maintenance cost is

zero.

CONCLUSION-

Functioning in a team environment Should follow assignment criteria closely Amount of detailed documents goes in a

professional project