1. i
CONSTRUCTION OF A UNIVERSAL REMOTE CONTROLLER
FOR ELECTRIC BULB AND CEILING FAN
BY
OTOBOR OGAGA
DSPT/COE/E/1213/3704
AND
OGWU FRANCES NDALIAKU
DSPT/COE/E/1213/3700
BEING A RESEARCH PROJECT SUBMITTED TO THE
DEPARTMENT OF COMPUTER ENGINEERING,
SCHOOL OF ENGINEERING,
DELTA STATE POLYTECHNIC, OTEFE-OGHARA.
IN PARTIAL FULFILMENT OF THE REQUIREMENT
FOR THE AWARD OF NATIONAL DIPLOMA (ND)
IN COMPUTER ENGINEERING
December, 2014
2. ii
CERTIFICATION
This is to certify that the construction of a universal remote controller for
electric bulb and ceiling fan was carried out by OTOBOR OGAGA and
OGWU FRANCES NDALIAKU under the supervision of MR. FELIX
OBOTOR has been duly approved for acceptance by the Department of
Computer Engineering, School of Engineering, Delta State Polytechnic
Otefe-Oghara.
_________________________
MR. FELIX OBOTOR Date
(Project supervisor)
ENGR. VICTOR OWEH Date
(Project Coordinator)
ENGR. VICTOR ENUKPERE Date
(Head of Department)
4. iv
ACKNOWLEDGMENT
First and foremost we thank God almighty for protecting us throughout the
time of this project and especially the period of our schooling. We thank our
parents Mr. and Mrs. Otobor and Mr. and Mrs. Francis A. Ogwu who gave
us all the support both financially and spiritual encouragement in our
academics and all endeavor of life.
We greatly appreciate our supervisor MR. FELIX OBOTOR for his selfless
assistance rendered to us in reviewing this project work and advices he gave
to us that brought this project to a successful end. We also appreciate our
Head of Department Engr. Enukpere E. Victor and our coordinator ENGR.
VICTOR OWEH whose guidance and support lead to the completion of this
project.
Lastly we thank our lecturers, friends and all those who have impacted
knowledge on us that has brought us to where we are today.
5. v
ABSTRACT
The paper presents a simple design and implementation of a universal
remote controller for fan and bulb light. It is a device that enables the user
to operate a fan and a bulb from approximately 10 meters away. The project
consists of two sections which are; the Transmitting section and the
Receiving side. The receiving side consists of a power supply section, a
microcontroller and Relays. It also houses the Infrared Receiving Sensor
circuit. The transmission side is a smaller component which is inform of a
hand held component. It has a power supply section that is powered using a
9v battery. The last major component contained in the transmitter side is the
Infrared emitter/sender which transmits signals received from the input
buttons to the receiving side of the system. This transmission is
accomplished wirelessly through the Infrared emitter/sender on the
Transmitter section.
6. vi
TABLE OF CONTENT
PAGE
Title Page - - - - - - - - - i
Certification - - - - - - - - - ii
Dedication - - - - - - - - iii
Acknowledgement - - - - - - - - iv
Abstract - - - - - - - - - - v
Table of Content - - - - - - - - vi
CHAPTER ONE:
1.0 Introduction - - - - - - - - 1
1.1 Background of project - - - - - - 1
1.2 Objective of the Study - - - - - - 3
1.3 Scope of the project - - - - - - 4
1.4 Limitation of the study - - - - - - 5
CHAPTER TWO:
2.0 Literature Review - - - - - - - 7
2.1 Review of remote control systems- - - - - 7
2.2 Resistor - - - - - - - - - 11
2.3 infrared transmitters and receivers - - - - - 16
2.4 Decade counter (CD4017) - - - - - 17
2.5 Light emitting diode (LED) - - - - - - 20
2.6 Relay - - - - - - - - 22
8. 1
CHAPTER ONE
1.0 INTRODUCTION
The first remote control called “lazy bones” was developed in 1950 by
zenith Electronics Corporation (then known as zenith radio cooperation).
The device was developed quickly, and it was called “zenith space
command” the remote went into production in the fall of 1956, becoming the
first practical wireless remote control device.
Today remote control is a standard on other consumer electronics products
including VCRS, cable satellite boxes, digital video disc (DVD) players and
home audio players. The most sophisticated TV sets have remote with as
many as 50 buttons. In year 2000, more than 99 percent of all VCR and
DVD players sold are equipped with remote controls. The average individual
these days probably picks up a remote control at least once or twice a day.
1.1 BACKGROUND OF PROJECT
Remote control facilitates the operation of fan regulators around the home or
9. 2
office from a distance. It provides a system that is simple to understand and
also to operate, a system that would be cheap and affordable, a reliable and
easy to maintain system of remote control and durable system irrespective of
usage. It adds more comfort to everyday living by removing the
inconvenience of having to move around to operate fan regulator or bulb
switch. The system seeks to develop a system that is cost effective while not
undermining the need for efficiency.
Basically, a remote control works in the following manner. A button is
pressed; this completes a specific connection which produces a Morse code
line signal specific to that button. The transistor amplifies the signal and
sends it to the L.E.D (light emitting diode) which translates the signal into
infrared light. The sensor on the appliance detects the infrared light and
reacts appropriately.
The remote control’s function is to wait for the user to press a key and then
translate that into infrared light signals that are received by the receiving
appliance. The carrier frequency of such infrared signals is typically around
10. 3
36KHz. Usually the transmitter part is constructed so that the transmitter’s
oscillator which drives the infrared transmitter LED can be turned on/off by
applying a TTL (transistor – transistor logic) voltage on the modulation
controlled input. On the receiver side, a photo transistor or photo diode takes
up the signals.
1.2 OBJECTIVES OF THE PROJECT
The aim of this project is to construct a digital remote controller by using
component a one’s disposal. The approach used in this work is the modular
approach where the overall design was broken into functional block
diagrams, where each block in the diagram represents a section of the circuit
that carries out a specific function. The system was design using a functional
blocks as shown below.
Infrared
Transmitter
Infrared
Sensor
Signal
Amplifier
Control
Logic
Sampler
Control
Stepper
Output
Control
logic
Load
Indicator Unit
11. 4
Fig 1.2: System Block Diagram
1.3 SCOPE OF THE PROJECT
The remote control device has the ability of sending the infrared signals
which is received by the infrared sensor. The mode of operation can be
understood as follow; at the application of voltage form the 12v battery
when the switch is closed, the 4013B oscillator IC (2), produces high and
low signal on pin 6, which is feed across the base of the 2sc 945 NPN
transistors. Thus when the output from the oscillators is high, there will be a
high voltage across the base of the NPN transistor which turn it ON. This
permits the infrared emitting diode to be grounded, resulting in the emission
diode to be grounded, resulting in the emission of an infrared ray. Also when
the output form the oscillator is low, there is low voltage across the base of
the NPN transistor, which result in no emission of an infrared ray from the
infrared emitting diode.
The 4013B oscillators IC produce a stream of pulse at a frequency
determined by the RC configuration on pin 11, 12, 13. The frequency of the
12. 5
oscillator is given by
FI = 1/C2
(3.R.C)
Where R = 33.103
C = 0.001 X 10-6
F
= 13.18KHZ
The pulse is connected to the base of the switching transistor (NPN 25C
945) through 91K𝛺 resistor. The pulse determines the frequency on the
infrared beam, such that its detection by the sampler would be possible.
ABBREVIATION OF TERMS
IC: Integrated Circuit
PNP: Positive Negative Positive
NPN: Negative Positive Negative
KHz: Kilohertz
13. 6
1.5 LIMITATION OF THE PROJECT
The remote control function is to wait for the users to press a key and
translate it into infrared light signal that are received by the receiving
appliances. The carried frequency of such infrared signals is typically around
36KHz. Often, the transmitter part is constructed in such a way that the
transmitter LED (Light Emitting Diode) can be turned ON/OFF by applying
a TIL voltage on the modulation controlled input. On the receiver side; a
phototransistor or photo diode takes up the signal.
More also the limit you can operate the remote is within 15 meters away.
Anything more that will not transfer the signal.
14. 7
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 REVIEW OF REMOTE CONTROL SYSTEMS
One of the earliest examples of remote control alert was developed in 1893
by Nikola Tesla. With the invention of Relays previously in 1835 by Joseph
Henry it became possible to use remote controls to drive other devices. This
is because of the ability or relays to serve as a switch that can control
devices when energized by electricity. Again with the invention of
Integrated Circuits like 555 timers and Microcontrollers, more functionality
was added to whole concept of Remote control alert.
The first remote intended to control a television was developed by Zenith
Radio Corporation in the early 1950’s and made use of wire to connect to
the television set. The remote — unofficially called "Lazy Bones" — used a
wire to connect to the television set. To improve the cumbersome setup, a
wireless remote control alert was created in 1955. The remote called
"Flashmatic" worked by shining a beam of light onto a photoelectric cell.
15. 8
Unfortunately, the cells did not distinguish between light from the remote
and light from other sources. The Flashmatic also required that the remote
control be pointed accurately at the receiver. In 1956 Robert Adler
developed "Zenith Space Command", a wireless remote. It was mechanical
and used ultrasound to change the channel and volume. When the user
pushed a button on the remote control it clicked and struck a bar, hence the
term "clicker". Each bar emitted a different frequency and circuits in the
television detected this noise. The invention of the transistor made possible
cheaper electronic remotes that contained a piezoelectric crystal that was fed
by an oscillating electric current at a frequency near or above the upper
threshold of human hearing, though still audible to dogs. The receiver
contained a microphone attached to a circuit that was tuned to the same
frequency. Some problems with this method were that the receiver could be
triggered accidentally by naturally occurring noises, and some people,
especially young women, could hear the piercing ultrasonic signals. There
was even a noted incident in which a toy xylophone changed the channels on
these types of TVs since some of the overtones from the xylophone matched
16. 9
the remote's ultrasonic frequency.
The impetus for a more complex type of television remote control alert came
in the late 1970s with the development of the Ceefax teletext service by the
BBC. Most commercial remote controls at that time had a limited number of
functions, sometimes only four: next station, previous station, and increase
or decrease volume. This type of control did not meet the needs of teletext
sets where pages were identified with three-digit numbers. A remote control
to select teletext pages would need buttons for each number from zero to
nine, as well as other control functions, such as switching from text to
picture, and the normal television controls of volume, station, brightness,
colour intensity and so on. Early teletext sets used wired remote controls to
select pages but the continuous use of the remote control alert required for
teletext quickly indicated the need for a wireless device. So BBC engineers
began talks with one or two television manufacturers which led to early
prototypes in around 1977-78 that could control a much larger number of
functions. ITT was one of the companies and later gave its name to the ITT
protocol of infrared communication. In the early 1980s, when
17. 10
semiconductors for emitting and receiving infrared radiation were
developed, remote controls alert gradually switched to that technology
which, as of 2006, is still widely used. Remotes using radio technologies,
such as Bose Audio Systems and those based on Bluetooth also exist.
By the early 2000s, the number of consumer electronic devices in most
homes greatly increased. According to the Consumer Electronics
Association, an average American home has four remotes. To operate a
home theater as many as five or six remotes may be required, including one
for cable or satellite receiver, VCR or digital video recorder, DVD player,
TV and audio amplifier. Several of these remotes may need to be used
sequentially, but, as there are no accepted interface guidelines, the process is
increasingly cumbersome. Many specialists, including Jakob Nielsen, a
renowned usability specialist and Robert Adler, the inventor of the modern
remote, note how confusing, unwieldy and frustrating the multiplying
remotes have become.
Most modern remote control alert systems for appliances use infrared diode
to emit a beam of light that reaches the device or equipment.
18. 11
Therefore the concept of remote control is further expanded in another form
by applying it in a circuit that is used to power many appliances
automatically by pressing buttons on the remote control.
The circuit consists of the following components resistors, transmitters,
receivers; decade counters logic control and indicators (LED) as well as high
current relays etc.
2.2 RESISTOR
A resistor is a passive two-terminal electrical component that implements
electrical resistance as a circuit element. Resistors act to reduce current flow,
and, at the same time, act to lower voltage levels within circuits. In
electronic circuits resistors are used to limit current flow, to adjust signal
levels, bias active elements, terminate transmission lines among other uses.
High-power resistors that can dissipate many watts of electrical power as
heat may be used as part of motor controls, in power distribution systems, or
as test loads for generators. Resistors can have fixed resistances that only
19. 12
change slightly with temperature, time or operating voltage. Variable
resistors can be used to adjust circuit elements (such as a volume control or a
lamp dimmer), or as sensing devices for heat, light, humidity, force, or
chemical activity.
Resistors are common elements of electrical networks and electronic circuits
and are ubiquitous in electronic equipment. Practical resistors as discrete
components can be composed of various compounds and forms. Resistors
are also implemented within integrated circuits.
The electrical function of a resistor is specified by its resistance: common
commercial resistors are manufactured over a range of more than nine orders
of magnitude. The nominal value of the resistance will fall within a
manufacturing tolerance.
The behavior of an ideal resistor is dictated by the relationship specified by
Ohm's law:
Ohm's law states that the voltage (V) across a resistor is proportional to the
current (I), where the constant of proportionality is the resistance (R). For
20. 13
example, if a 300 ohm resistor is attached across the terminals of a 12 volt
battery, then a current of 12 / 300 = 0.04 amperes flows through that resistor.
Practical resistors also have some inductance and capacitance which will
also affect the relation between voltage and current in alternating current
circuits.
The ohm (symbol: Ω) is the SI unit of electrical resistance, named after
Georg Simon Ohm. An ohm is equivalent to a volt per ampere. Since
resistors are specified and manufactured over a very large range of values,
the derived units of milliohm (1 mΩ = 10−3
Ω), kilohm (1 kΩ = 103
Ω), and
megohm (1 MΩ = 106
Ω) are also in common usage.
2.2.1 SERIES AND PARALLEL RESISTORS
Fig 2.2.1 (a): resistors in series
21. 14
The total resistance of resistors connected in series is the sum of their
individual resistance values.
RT = R1 + R2 + Rn
The total resistance of resistors connected in parallel is the reciprocal of the
sum of the reciprocals of the individual resistors.
1
𝑅 𝑇
=
1
𝑅1
+
1
𝑅2
+
1
𝑅 𝑛
So, for example, a 10 ohm resistor connected in parallel with a 5 ohm
resistor and a 15 ohm resistor will produce the inverse of 1/10+1/5+1/15
ohms of resistance, or 1/(.1+.2+.067)=2.725 ohms.
22. 15
2.2.2 TYPE OF RESISTORS SYMBOLS
1. Standard resistors
2. Variable resistors
2.2.2.1 STANDARD RESISTORS
These are resistors that have a fixed resistance value. They are usually in the
form of length of resistance wire or piece of carbon or metal film.
2.2.2.2 VARIABLE RESISTORS
These are resistors whose resistance can be varied. They are use as voltage
divider network.
2.2.3 RESISTOR COLOUR CODING
Resistors (carbon resistors) are color coded to mark their resistance value in
ohms. The basic system is to use the color code of resistor to calculate its
resistance using the standard color numerical values listed in table 2.2.3
23. 16
TABLE 2.2.3 RESISTOR COLOUR CODE TABLE
COLOUR CODE VALUE MULTIPLIER TOLERANCE BAND
BLACK 0 100
-
BROWN 1 101
±1%
RED 2 102
±2%
ORANGE 3 103
-
YELLOW 4 104
-
GREEN 5 105
±0.5%
BLUE 6 106
±0.25%
VIOLET 7 107
±0.1%
GREY 8 108
-
WHITE 9 109
-
SILVER - 10-1
±10%
GOLD - 10-2
±5%
Fig 2.2.3 Resistor
2.3 INFRA RED TRANSMITTERS AND RECIEVERS
Infrared (IR) radiation is electromagnetic radiation of a wavelength longer
1st
Digit Band
2nd
Digit
Band
Decimal
Multiplier
Tolerance
24. 17
than that of visible light, but shorter than that of radio waves. The name
means "below red" (from the Latin infra, "below"), red being the color of
visible light of longest wavelength. Infrared radiation spans three orders of
magnitude and has wavelengths between approximately 750 nm and 1 mm.
Infra-red light is just below the red portion of the visible spectrum, and so is
invisible to the human eye.
Infrared transmitters are the devices that transmit signals through Infrared
and these signals are received by Infrared receivers. Infrared receivers are
signal sensors which are capable of receiving infrared rays and is able to
transform this rays to an intended function.
2.4 DECADE COUNTER (CD4017)
The CD4017 is the one of the most popular Decade Counter (Divided by 10
Counter). It is a 5 Stage Divide by 10 Johnson Counter with 10 Decoded
outputs. It has a wide supply voltage range from 3V to 15V and is
compatible with TTL. It has a medium speed of operation, typically 5Mhz.
Its applications includes industrial electronics, remote metering, automotive,
25. 18
medical electronics, instrumentation and alarm systems.
The above diagram shows the pin out of CD4017B, Dual-In-line package.
2.4.1 Pin Functions
Vcc
It is the supply voltage terminal of the IC. Being a CMOS IC it has a wide
supply voltage range from 3V to 15V.
Vss
It is the ground pin or common pin of the IC CD4017. It should be
connected to the negative terminal of the DC Power supply or battery.
Q0 – Q9
These are the 10 decoded outputs of the CD 4017 IC. One of the 10 decoded
outputs may be high at a time.
Clock
It is the clock pin of the counter. Q0 goes high during the rise of the first
26. 19
clock cycle. Q0 goes low and Q1 goes high during the rise of the second
clock cycle, and so on..
Clock Enable
This is the active low enable pin for clock input. If this input is high the
counter will not count clock cycles.
Carry Out
This pin is used to indicate that the count exceeds 10. This pin goes low
when the output Q5 goes high and goes high when the output Q0 goes high.
Reset
This is the reset pin of the IC. When this pin goes high, the output pin Q0
will go high.
27. 20
Fig 2.4: CD4017 pin diagram
2.5 LIGHT EMITTING DIODE (LED)
A light-emitting diode (LED) is a two-lead semiconductor light source. It is
a basic pn-junction diode, which emits light when activated. When a fitting
voltage is applied to the leads, electrons are able to recombine with electron
holes within the device, releasing energy in the form of photons. This effect
is called electroluminescence, and the color of the light (corresponding to
the energy of the photon) is determined by the energy band gap of the
semiconductor.
An LED is often small in area (less than 1 mm2
) and integrated optical
components may be used to shape its radiation pattern.
28. 21
Appearing as practical electronic components in 1962, the earliest LEDs
emitted low-intensity infrared light. Infrared LEDs are still frequently used
as transmitting elements in remote-control circuits, such as those in remote
controls for a wide variety of consumer electronics. The first visible-light
LEDs were also of low intensity, and limited to red. Modern LEDs are
available across the visible, ultraviolet, and infrared wavelengths, with very
high brightness.
Early LEDs were often used as indicator lamps for electronic devices,
replacing small incandescent bulbs. They were soon packaged into numeric
readouts in the form of seven-segment displays, and were commonly seen in
digital clocks.
Recent developments in LEDs permit them to be used in environmental and
task lighting. LEDs have many advantages over incandescent light sources
including lower energy consumption, longer lifetime, improved physical
robustness, smaller size, and faster switching. Light-emitting diodes are now
used in applications as diverse as aviation lighting, automotive headlamps,
advertising, general lighting, traffic signals, and camera flashes. However,
29. 22
LEDs powerful enough for room lighting are still relatively expensive, and
require more precise current and heat management than compact fluorescent
lamp sources of comparable output.
LEDs have allowed new text, video displays, and sensors to be developed,
while their high switching rates are also useful in advanced communications
technology.
On October 7, 2014, the Nobel Prize in Physics was awarded to Isamu
Akasaki, Hiroshi Amano and Shuji Nakamura for "the invention of efficient
blue light-emitting diodes which has enabled bright and energy-saving white
light sources" or, less formally, LED lamps.
2.6 RELAYS
Fig 2.6: Relay
A relay is an electrically operated switch. Current flowing through the coil of
30. 23
the relay creates a magnetic field which attracts a lever and changes the
switch contacts. The coil current can be on or off so relays have two switch
positions and they are double throw (changeover) switches.
Relays allow one circuit to switch a second circuit which can be completely
separate from the first. For example a low voltage battery circuit can use a
relay to switch a 230V AC mains circuit. There is no electrical connection
inside the relay between the two circuits; the link is magnetic and mechanical.
The coil of a relay passes a relatively large current, typically 30mA for a 12V
relay, but it can be as much as 100mA for relays designed to operate from
lower voltages. Most ICs (chips) cannot provide this current and a transistor is
usually used to amplify the small IC current to the larger value required for
the relay coil. The maximum output current for the popular 555 timer IC is
200mA so these devices can supply relay coils directly without amplification.
Relays are usually SPDT or DPDT but they can have many more sets of
switch contacts, for example relays with 4 sets of changeover contacts are
readily available. For further information about switch contacts and the terms
31. 24
used to describe them please see the page on switches.
Most relays are designed for PCB mounting but you can solder wires directly
to the pins providing you take care to avoid melting the plastic case of the
relay.
The supplier's catalogue should show you the relay's connections. The coil
will be obvious and it may be connected either way round. Relay coils
produce brief high voltage 'spikes' when they are switched off and this can
destroy transistors and ICs in the circuit. To prevent damage you must
connect a protection diode across the relay coil.
The animated picture shows a working relay with its coil and switch contacts.
You can see a lever on the left being attracted by magnetism when the coil is
switched on. This lever moves the switch contacts. There is one set of
contacts (SPDT) in the foreground and another behind them, making the relay
DPDT.
The relay's switch connections are usually labeled COM, NC and NO:
● COM = Common, always connect to this; it is the moving part of the
32. 25
switch.
● NC = Normally Closed, COM is connected to this when the relay coil
is off.
● NO = Normally Open, COM is connected to this when the relay coil is
on.
● Connect to COM and NO if you want the switched circuit to be on
when the relay coil is on.
● Connect to COM and NC if you want the switched circuit to be on
when the relay coil is off.
2.7 TRANSISTOR
A transistor consists of two PN- junction formed by sandwiching either p-
type or n-type semiconductor between a pair of opposite types. Accordingly;
there are two types of transistors viz;
1. NPN transistor and
2. PNP transistor.
An n-p-n transistor is composed of two n-type semi conductors separated by
33. 26
a thin section of p-type as shown in fig.2.7(i).
However, a p-n-p transistor is formed by two p-sections separated by a thing
section of n-type as shown in fig 2.7 (ii)
Fig 2.7 (i): NPN transistor Fig 2.7(ii): PNP Transistor
2.7.1 NAMING THE TRANSISTOR TERMINAL
A transistor (PNP or NPN) has three section of doped semiconductors. The
section on one side is the emitter and the section is called the base and form
two junction between the emitter and collector.
Fig 2.7.1: The transistors and its terminals
P NN PP N
34. 27
2.7.1.1 EMITTER
It is the section that supplies charge carrier (electron or holes). The emitter is
always forward biased with respect to the base so that it can supply a large
number of majority carriers (hole if emitter is p-type and electron if it is N-
type).
2.7.1.2 COLLECTOR
It is the section that collects the charge. It is always reverse biased. It
function is to remove charge from its junction with the base. The collector is
reverses biased and receives holes charge that flows. In the output circuit for
PNP transistor and electron for NPN transistors.
2.8 BRIDGE RECTIFIER
A bridge rectifier can be made using four individual diodes, but it is also
available in special packages (like the one used in this design) containing the
four diodes required. It is called a full-wave rectifier because it uses the entire
AC wave (both positive and negative sections). 1.4V is used up in the bridge
rectifier because each diode uses 0.7V when conducting and there are always
two diodes conducting, as shown in the diagram below. Bridge rectifiers are
35. 28
rated by the maximum current they can pass and the maximum reverse
voltage they can withstand (this must be at least three times the supply RMS
voltage so the rectifier can withstand the peak voltages).
By contrast, rectifier diodes and bridges for use in power supplies are hefty
objects with current ratings going from 1 to 25 amps or more and breakdown
voltages going from 100 volts to 1000 volts. They have relatively high
leakage currents (in the range of micro amps to milliamps) and plenty of
junction capacitance.
Figs 2.8(a): Circuit symbol for bridge rectifier
36. 29
Fig 2.8(b): Output: full-wave varying DC
2.9 TRANSFORMER
A transformer is a device consisting of two closely coupled coils (called
primary and secondary). An ac voltage applied to the primary appears across
the secondary, with a voltage multiplication proportional to the turns ratio of
the transformer and a current multiplication inversely proportional to the turns
ratio. Power is conserved. Figs 2.9 shows the circuit symbol for a laminated-
core transformer (the kind used in this design- 50Hz ac power conversion).
Figs 2.9: Circuit symbol of a Transformer
Transformers are quite efficient (output power is very nearly equal to input
power); thus, a step-up transformer gives higher voltage at lower current. A
transformer of turns ratio n increases the impedance by n2
. There is very little
primary current if the secondary is unloaded.
37. 30
Transformers serve two important functions in electronic instruments:
● They change the ac line voltage to a useful (usually lower) value that
can be used by the circuit.
● They “isolate” the electronic device from actual connection to the
power line, because the windings of a transformer are electrically
insulated from each other.
Power transformers (meant for use from the 220V power line) come in an
enormous variety of secondary voltages and currents: output as low as 1 volt
or so up to thousand volts, current ratings from a few milliamps to hundreds
of amps.
2.10 DIODES
A diode is a two terminal, passive and non-linear that can be used to control
voltage and current in a circuit. Some diodes are used primarily to rectify
alternating current, voltage regulation, indicators, signals source or optical
detectors.
38. 31
2.10.1 TYPES OF DIODE SYMBOLS
1. Ordinary or crystal diode
2. Schottky diode
3. Zener diode
4. Light Emitting Diode (LED)
2.10.2 APPLICATION OF DIODE
Diodes are used as;
1. Rectifier, to convert alternating current to direct current.
2. Voltage regulator
3. Protecting device against switching polarity.
2.10.3 ORDINARY OR CRYSTAL DIODE AS RECTIFIER: HALF WAVE
RECTIFIER
In the half wave rectification, the rectifier conducts current only during the
half cycle of input A.C supply. The negative half cycle of A.C supply as
supposed, that is during negative half cycle, no current is conducted and
hence no voltage appears across the load. Therefore, current always flows in
39. 32
one direction through the load though after every half cycle. Fig 2.10.3 (a)
and (b) shows circuit diagram and wave forms respectively for half wave
rectifier
(a) (b)
Fig 2.10.3 (a) & (b) shows circuit diagram and wave forms respectively for
half wave rectifier
2.10.4 FULL- WAVE BRIDGE RECTIFIER
The need for a centre tapped power transformer is eliminated in the bridge
rectifier. It contains four diode; D1, D2, D3, and D4 connected to form
bridge as shown in fig. 2.4.4(a). The A.C supply to be rectifier is applied to
the diagonally opposite ends, of the bridge through the transformer. Between
40. 33
other two ends of the bridge, the load is connected.
(a) (b)
Fig 2.10.4 full-wave bridge rectifier
2.11 CAPACITOR
A capacitor is a device for storing electric charges or for storing electricity.
It consists essentially of two conductors (metal plate) carrying opposite
charges. The metal plate are separated a distance (D), by insulators or
dielectric material.
Fig.2.11 capacitor
Dielectric
Q Q
Metal Plate
+ -
41. 34
The capacitance (C) of a capacitor is the ratio of the charge (Q) on either
plate or conductors to the potential difference (V) between them.
` C = QV
Its unit is the farad. The capacitance of a capacitor is a measure of its ability
to store up electricity. The capacitance (c) is a constant for a given capacitor.
The value of the capacitance depends on the size, shape, distance separating
the two plates, and also on the nature of the material that separates them and
the common area of plates.
2.11.1 ARRANGEMENT OF CAPACITOR - SERIES AND PARALLEL
ARRANGEMENT
Figure 2.11.1 shows two different arrangements of capacitors in a circuit. In
(a) the capacitors are arranged in series, in (b) the capacitor are arranged in
parallel.
42. 35
a. Capacitors in series
b. Capacitors in parallel
Fig. 2.11.1 Arrangement of capacitors
It can be shown that the equivalent (c) for the capacitor in series is given by;
1/CT =1/C1 + 1/C2 + 1/C3
While for parallel, is given by;
CT = C1 + C2 + C3
2.11.3 TYPES OF CAPACITOR SYMBOLS
Capacitor
Polarized capacitor
Variable capacitor
-
-
C3C2C1
43. 36
Trimmer capacitor
2.11.4 APPLICATION CAPACITOR
Capacitors are used in;
1. Radio circuit for tuning.
2. Ignition system for motor vehicle.
3. The elimination of spark when a circuit containing Inductance is
suddenly opened.
4. As a filter: it is to filter off A.C signals.
44. 37
CHAPTER THREE
3.0 DESIGN ANALYSIS
The block diagram of the universal remote controller for electric bulbs and
ceiling fans system is as shown below.
Fig 3.0 block diagram of the system
Infrared
Transmitter
Infrared
Sensor
Signal
Amplifier
Control
Logic
Sampler
Control
Stepper
Output
Control
logic
Load
Indicator Unit
45. 38
3.1 CIRCUIT OPERATIONS
This project describes a technique of adding the remote control feature to an
electrical appliance. The goal is to construct a black box where you can
plug-in your 220V AC appliance (it can be easily modified for 110V mains
supply too) and control the ON and OFF operations with a TV or DVD
remote that uses modulated infra-red (IR) pulse train of 38 KHz frequency.
Uses a TSOP1738 IR receiver module at the input side to receive the 38
KHz frequency IR pulses from the remote control. Under normal condition,
the output pin of the IR module is at logic High, which means the transistor
T1 (BC557 PNP) is cut-off and its collector terminal is at logic Low. The
collector of T1 drives the clock line of the CD4017 decade counter. When
somebody faces a TV or DVD remote towards the TSOP1738 and presses
any key on it. The TSOP 1738 module receives the train of 38 KHz IR
pulses from the remote that makes its output to oscillate too. These pulses
are inverted at the collector of T1, which finally go to the clock input of the
decade counter. The arriving pulses could increment the CD4017 counter at
46. 39
the same rate (38 KHz), but because of the presence of the RC filter circuit
(R1 = 100K, C1 = 10 𝛺F) between the collector and the ground, the train of
pulses appear as a single pulse to the counter.
Thus, on each key pressing, the CD4017 counter advances only by a single
count. When the user releases the key, the C1 capacitor discharges through
the R1 resistor, and the clock line is back to zero. So every time the user
presses and releases a key on the remote, the CD4017 counter receives a
single pulse at its clock input. Initially, when the circuit is just powered on,
the Q0 output of the CD4017 decade counter goes high. The counter
increments for each low-to-high going pulse arriving at its CLK pin (14).
When the first pulse arrives, Q0 goes Low and Q1 is turned High. This
activates the relay and the AC appliance connected to it is turned on. The
status LED connected to Q1 also glows to indicate the appliance is switched
on. When the user presses a key again, the second pulse arriving at the CLK
line increments the counter by 1. This makes Q1 back to Low (which means
the relay is deactivated and the appliance is turned off) and Q2 is pulled
High. Since Q2 is wired to the Reset input, the second key press actually
47. 40
brings the CD4017 IC back to the power-on-reset conditions with Q0 High.
Thus, it basically operates as an ON/OFF toggle switch controlled with any
key of an infrared remote.
Fig 3.1: Circuit Diagram
48. 41
3.2. POWER SUPPLY
The power supply for the circuit can be derived from the mains AC itself
using a step down transformer and a bridge-rectifier circuit For +5V power
supply. Circuits usually require a dc power supply that can maintain a fixed
voltage while supplying enough current to drive a load. Batteries make good
dc supplies, but their relatively small current capacities make them
impractical for driving high-current, frequently used circuits. An alternative
solution is to take a 120V ac, 60-Hz line volt- age and convert it into a
usable dc voltage. The trick to converting the ac line voltage into a usable
(typically lower-level) dc voltage is to first use a transformer to step down
the ac voltage. After that, the transformed voltage is applied through a
rectifier network to get rid of the negative swings (or positive swings if you
are designing a negative voltage supply). Once the negative swings are
eliminated, a filter network is used to flatten out the rectified signal into a
nearly flat (rippled) dc voltage pattern. Now there is one problem with this
supply—it is unregulated. This means that if there are any sudden surges
within the ac input voltage (spikes, dips, etc.), these variations will be
49. 42
expressed at the supply’s output (notice the spike that gets through in Fig.
10.1). Using an unregulated supply to run sensitive circuits (e.g., digital IC
circuits) is a bad idea. The current spikes can lead to improper operating
characteristics (e.g., false triggering, etc.) and may destroy the ICs in the
process. An unregulated supply also has a problem maintaining a constant
output voltage as the load resistance changes. If a highly resistive (low-
current) load is replaced with a lower- resistance (high-current) load, the
unregulated output voltage will drop (Ohm’s law).
Fortunately, there is a special circuit that can be placed across the output of
an unregulated supply to convert it into a regulated supply, a supply that
eliminates the spikes and maintains a constant output voltage with load
variations this special circuit is called a voltage regulator. One popular line
of regulators includes the three-terminal LM78xx series shown here. The
“xx” digits represent the output voltage, e.g., 7805 (5V), 7806 (6V), 7808
(8V), 7810 (10V), 7812 (12 V), 7815 (15 V), 7818 (18 V) and 7824 (24 V).
These devices can handle a maximum output current of 1.5A if properly
heat-sunk. To remove unwanted input or output spikes/ noise, capacitors can
50. 43
be attached to the regulator’s input and output terminals, as shown in the
figure. A popular series of negative voltage-regulator IC is the LM79xx
regulators, where “xx” represent the negative output volt- age. These devices
can handle a maximum out- put current of 1.5 A.A number of different
manufacturers make their own kinds of volt- age regulators. Some of the
regulators can handle more current than others.
3.2.1 The Transformer
It is important that you choose the right transformer for your power supply.
The transformer’s secondary voltage should not be much larger than the
output voltage of the regulator; otherwise, energy will be wasted because the
regulator will be forced to dissipate heat. However, at the same time, the
secondary voltage must not drop below the required minimum input voltage
of the regulator (typically 2 to 3 V above its output voltage).
3.2.2 Rectifier Packages
The three basic rectifier networks used in power supply designs include the
half- wave, full-wave, and bridge rectifiers. To understand how these
51. 44
rectifiers work. Half-wave, full-wave, and bridge rectifiers can be
constructed entirely from individual diodes. However, both full-wave and
bridge rectifiers also come in preassembled packages. Make sure that the
power supply’s rectifier diodes have the proper current and peak-inverse-
voltage (PIV) ratings. Typical rectifier diodes have current ratings from 1 to
25 A, PIV ratings from 50 to 1000 V, and surge-current ratings from around
30 to 400 A. Popular general-purpose rectifier diodes include the 1N4001 to
1N4007 series (rated at 1 A, 0.9-V forward voltage drop), the 1N5059 to
1N5062 series (rated at 2 A, 1.0-V forward voltage drop), the 1N5624 to
1N5627 series (rated at 5 A, 1.0-V forward voltage drop), and the 1N1183A-
90A(rated at 40 A, 0.9-V forward voltage drop). For low-voltage
applications, Schottky barrier rectifiers can be used; the voltage drop across
these rectifiers is smaller than a typical rectifier (typically less than 0.4 V);
how- ever, their breakdown voltages are significantly smaller. Popular full-
wave bridge rectifiers include the 3N246 to 3N252 series (rated at 1A, 0.9-V
forward voltage drop) and the 3N253 to 3N259 series (rated at 2 A, 0.85-V
forward voltage drop).
52. 45
CHAPTER FOUR
4.0 CONSTRUCTION AND TESTING
In the world of construction, availability of working equipment or tools are
to be paramount. The following are the methods that show the step to step
construction of the universal remote controller for fan and bulb light.
4.1 SELECTING YOUR APPARATUS
The first step or method to start the project is by knowing your apparatus,
which are the electronic components needed for the design. Electronic
component are components that are used together to achieve a working
circuit. The circuit consist of the following apparatus; resistors, transmitter,
receivers, decade counters logic controls and indicators (LED) as well as
high current relays etc. The power supply consists of bridge rectifier,
transformer and capacitors, not neglecting the device casing/compartment as
another important apparatus.
53. 46
4.2 MOUNTING OF ELECTRONIC COMPONENTS
The construction is started by the systematic analysis and calculations as
well as logical reasoning, to suit the nature of the expected finished product
that is required. The components must be mounted based on the circuit
diagrams presented and also space needs to be managed and put into
consideration when handling any electronic project, as it can either increase
the cost of the project or reduce the cost of the project. When space is not
managed, it gives us finished product that will need to occupy a larger
casing size than when space management is accurate. Mounting should be
done in a systematic arrangement and also should start with the sockets of
the integrated circuits (I.C) and then the resistors follows.
4.3 SOLDERING OF ARRANGED COMPONENTS
The term soldering is the act of adding solders to the copper oriented Vero-
board that is housing the terminals of the electronic component in between
holes in order to ascertain connectivity and firmness as well as providing
conductivity moulds to link components that are far apart, we can consider
the use of linking leads (connecting wires or jumpers) or the use of printing
54. 47
format with solders. The printing methods involve the use of soldering leads
to produce a link between two components that are far apart in order to
achieve a conductive pattern in a straight line. The printing method in the
recent years have proved to be the best according to design analyst, starting
that linking leads such as connecting wires can add to the impedance of the
circuits, thereby causing abnormalities in the circuit functions.
4.4 CONTINUITY TESTS
The continuity test involves the use of multi meters to check the connections
which involves a systematic movement all over the circuit with the aid and
guide of the circuit’s diagram. Wrong connections can lead to the
malfunctioning of the project, and also can lead to the damage of sensitive
electronic components e.g. integrated circuits, which can cause increase in
the projects time duration and cost during construction.
4.5 TESTING AND CASING/PACKAGING
After the continuity test, we need to test so as to check for other errors (such
as human error and systematic errors) after which when rectified and ready,
after which it is placed for casing.
55. 48
The casing should be presentable addressable as it is the beauty of the
project.
56. 49
CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION
5.1 CONCLUSION
One of the primary objectives of an engineer is to Endeavour to deliver the
best product or the most efficient services at the lowest cost to the end user.
The system has been tested and was found to meet the expected result.
The aim of this work was to design and construct a remote controller for fan
and light regulator, and the system has thus accomplished that. The remote
control device sends an infrared beam, which is received by the infrared
sensor on the regulator, the display on the regulator indicates a change in
fan.
5.2 RECOMMENDATION
This project is a viable one in the sense that it will go a long way in making
it more convenient easier for users to easily control their fan and light
regulator from a central point in their home using a remote control which has
buttons for controlling each appliance connected to the system. Because of
57. 50
its importance as a household need, efforts must be geared towards
designing a viable project like this one. I strongly recommend that the
department should see this project as a priceless possession and should
endeavor to provide financial assistance and more research works relating to
this project to support and encourage students embarking on this type of
project so as to be used to be used not only in homes but also in offices,
schools etc.
58. 51
REFERENCES
555 timer tutorials, Available at: http://www.electroniclab.com, 2002.
Ahmed M. S., Mohammed A. S., Onimole T. G., Attah P. O., Design and
construction of a remote Controlled fan regulator, Leonardo
Electronic Journal of Practices and Technologies, 2006, 9, p. 55-62.
Horowitz, P. (1986) The art of Electronics 2nd
Edition.
Leonard S.B., Fundamentals of electrical engineering, Oxford University
press, Inc New York, 1996.
SB-Projects, Infra-Red Remote Control Theory, Available at:
http://www.sbprojects.com, 2004.
Schuler, A.C. (1999) Elections Principles and Application. 5th
Edition.
Theraja B. L., Theraja A. K., Electrical Technology, 2002 Edition; S. Chand
and Company Ltd. India, 2002.
Tokhein, R.L. (1995) Digital Electronics Principles and Application 5th
Edition.
Tokhein L. Digital electronics, electrical and electronics series, Glencoe
division of Macmillan, McGraw Hill School, 1994.
59. 52
Wiky, J. and Sons (1977) Practical Digital Design New York.