It's a rf based home appliance control system

1. 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 fulfillmentof the requirementfor 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

2. RAJARSHI RANANJAY SINH INSTITUTE OF
MANAGEMENT AND TECHNOLOGY
AMETHI
(Affiliated to Gautam Buddh Technical University Lucknow)
( 2011 – 2012 )
CERTIFICATE
This 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)

3. 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)

4. CONTENTS
1. Chapter 1
a. Overview
2. Chapter 2
a. Introduction
b. Block Diagram
c. Circuit diagram
3. Chapter3
Program used in Project
4. Chapter4
a) Component Description
b) Scope
c) Use of Project
d) Limitation
5. Chapter5
a. Conclusion
b. Bibliography

5. 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.

7. 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, Thisis 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

8. 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

9. 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

10. 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

11. 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),

14. CIRCUIT DIAGRAM –

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

16. 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

17. 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

18. information you'll need to establish an effective RF communications
network using the BASIC Stamp with the TWS/RWS RF modules.

19. 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:

20. 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

21. 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.

22. 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

23. 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.

24. 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:

25. 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.

26. 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

27. 
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

28. 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

29. 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.

31. 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

32. 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.

33. 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

34. 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.

35. 8. BASIC ELECTRONICS COMPONENTS
9.
10. Electronicscan at first seem extremely complicated
to understandand learn. One look at a circuit board
with all those little blinky LED's and black chips and
unidentifiablecircle pointy things can make anyone
quit before starting.
11. But actuallyelectronics can be much simpler than
you think. Learning electronicsis more like learning a
foreign language alphabet. At first glance it is all a
bunch of squiggles. But actuallyeach letterhas its own
pronounciation and its own rules of use. And certain
combinationsof 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 capacitoror transistor,
has special rules and abilities. Combining a few into a
circuit can create interesting effects. Combine a bunch
of unrelatedcircuits together and suddenlyyou have a
robot. So your first step would just to be to learn and
understandthe 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 electronicsis designed to manipulate a flow of
electrons. Electronshave mass and volume so you can
almost think of electronsin circuits as water flowing

36. through plumbing. The analogy is amazingly helpful
if you think about it. Also note, the more electronsyou
have in one place, the higher the voltage. The more
electronsmoving 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 electronscoming from the source,
and heading to the ground. A quick note, in reality
electronsmove from gound to source. The confusion
has historical reasons I dont want to get in to. But just
know this fact, and pretend electronsmove from source
to ground.
15. Now think of this as water.

37. 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 controlhow much current goes down each
wire
- they can controlpower usage
- they can controlvoltages (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, supposeyou take a resistor and connect the
two ends of a batterywith it. You know that your
battery is 9V (or whatever) and you know the resistor is
3Kohm (determined by the colorstripes on the resistor),
so 9V divided by 3Kohmis .003amps (3 milliamps). So
why is this information useful? Well now that you
know the current, you can determine otheruseful things

38. 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 valueof 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
onlinealready so I won't, just google search 'resistor
colortutorial.'
Click for a quick resistorcolorcode reference chart.
20.
CAPACITORS
Now supposeyou want to controlhow 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
fluctuationsin 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.

39. Capacitors are somewhat complex in theory, but most
peoplecan 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 electronsto 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
capacitorhas 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 capacitorcan never be fully
charged or discharged, but in reality this is never the

40. case.
23. So how can you use capacitors in your robot?
24. Power surge/drainagemanagement.
25. The problemwith using robot componentsthat drain
a large amount of power is sometimes your battery
cannot handlethe high drain rate. Motorsand 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 controlcircuitry and your motors. So don't do it.
26. Or supposeyour robot motors are not operatingat it's
full potential because the battery cannot supplyenough
current, the capacitor will make up for it. The solution
is to place a large electrolytic capacitorbetween the
source and ground of your power source. Get a
capacitorthat is rated at least twice the voltage you
expect to go through it. Have it rated at 1uF-10uFfor
every amp required. For example, if your 20V motors
will use 3 amps, use a 3uF-30uF50V 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

41. 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 electronsand your circuit
will be left with a deficit. It is also bad to allow a large
capacitorto remain fully charged when you turn off
your robot. Things could accidentlyshort and fry, such
as curious kitties that get too close. So use a simple
power on LED in your motor circuit to drain the
capacitorafter your robot is turned off. If your capacitor
is not rated properlyfor voltage, then can explodewith
smoke. Fortunatelythey do not overheat if given
excessive amounts of current. So just make sure your
capacitoris rated higher than your highest expected.
27. Capacitors can also be used to prevent power spikes
that could potentiallyfry circuitry. Next to any on/off
switch or anything that that could affect power
suddenlyshould have a capacitor across it.
28. Capacitors can eliminate switch bouncing. When
you flip a mechanical switch, the switch actually
bouncesseveral times within a microsecond range.
Normally this is too small of a time for anyone to care
(or even notice), but note that a microcontrollercan
take hundredsof readings in a single microsecond. So if
your robot was countingthe 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 capacitancevalue.

42. 29. Capacitors can improve efficiency and longevity of
electric motors up to 100%. Place a small ceramic
capacitorof 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 capacitorswill 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. Motordrivers and

43. MOSFETs would too. Diodes are also useful for
droppinghigh voltages to a lower more usablevoltage.
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-linearlyas voltage
changes linearly.
32.
33. There is anotherspecial diode called a zener diode.
With the water analogy, a zener diode is like a dam, but
with a pump at the bottompumping 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 probablynever need to use a
zener diode.

44. 34.

45. 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.

46. 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:

47. 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

48. (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:

49. 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

50. 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

51.  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

52.  Power supply current: Needed output current + 5
mA
 Component costs: Few dollars for the electronics
components + the input transformer

53. 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

54. Controlled Devices
The following devices will be controlled by the microcontroller:
 Fan
 Light
 Digital thermostat
Controlled Devices - Fan

56. Controlled Devices – Light
120VAC
STK300
port B, bit 0
Power from
outlet
Manual/Remote
select
STK300
port B bit 1
Light Switch
Control
relay

57. 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

58. 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
froma 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 involvedfor making and
operating the circuit is
minimum.
3. Low power requirementand maintenance cost is
zero.

59. CONCLUSION-
Functioning in a team environment
Should follow assignment criteria closely
Amount of detailed documents goes in a professional
project