Download dc motor control

“Transforming Live, Inventing Future”
A
Project Report
On
DC MOTOR CONTROL
USING PWM
By
1. Parmar Bhadresh C. (106030311025)
2. Bhimani Ravi J. (106030311026)
3. Makwana Smit Y.(106030311014)
DEPARTMENT OF ELECTRONICS & COMMUNICATION
ENGINEERING
ATMIYA INSTITUTE OF TECHNOLOGY AND SCIENCE FOR
DIPLOMA STUDIES, RAJKOT- 360005.
[2012– 2013]
A
Project Report
On
DC MOTOR CONTROL
USING PWM
In partial fulfillment of requirements for the degree of
Diploma of Engineering
In
EC Engineering
Submitted By:
Under the Guidance of
1.Parmar Bhadresh C.-106030311025
Mr. Mayur C. Patel
2. Bhiimani Ravi J.-106030311025
3. Makwana Smit Y.-106030311014
DEPARTMENT OF ELECTRONICS & COMMUNICATION
ENGINEERING
ATMIYA INSTITUTE OF TECHNOLOGY AND SCIENCE FOR
DIPLOMA STUDIES, RAJKOT- 360005.
[2012– 2013]
ACKNOWLEDGEMENT
I greatly thank my faculty guide of the college Mr. Mayur Patel. I m also
thankful to my external guide and chair person of the industry I visited Mr.
Satish Goswami. Mr. Satish Goswami is a very genuine person and gave me
training giving time from his busy schedule. Lastly I heartily thank all my
friends and parents who guided and motivated me to complete my project
successfully.
Parmar Bhadresh C.
Bhimani Ravi J.
Makwana Smit Y.
Contents
Abstract ..................................................................................................................................... I
List Of Figures ......................................................................................................................... II
List Of Tables ......................................................................................................................... III
(1) Introduction ....................................................................................................................... 1
1.1 Industry Visited ............................................................................................................... 1
(2) Problem definition ............................................................................................................. 3
2.1Detailed problem definition ............................................................................................. 3
2.2 Problem in the machine .............................................................................................. 7
(3) Feasibility ........................................................................................................................... 8
3.1Financial feasibility .......................................................................................................... 8
3.2 Resource feasibility: ................................................................................................... 8
3.3 Technical feasibility ................................................................................................ 9
(4) Hardware Description..................................................................................................... 10
4.1 Circuit Diagram ............................................................................................................. 10
4.2 List of components .................................................................................................... 10
4.3 Physical diagram ................................................................................................ 11
4.3.1 operation…………………….……………………………………………….11
(5) Component detail ............................................................................................................ 13
(I) Resister ....................................................................................................................... 13
(II) Capacitor ....................................................................................................... 16
(III) Diode ............................................................................................................ 19
(IV) LED ............................................................................................................. 23
(V) MOSFET ....................................................................................................... 27
(VI) IC (LM324).................................................................................................. 37
(VII) Variable resister.......................................................................................... 39
(6) Project design .............................................................................................................. 47
6.1 Software design ....................................................................................................... 47
6.2 Hardware design .................................................................................................. 48
6.2.1 PCB designing steps……………………………………………………… 49
(7) Component Testing ..................................................................................................... 52
7.1 Resister Testing……………………………….…………………………………...52
7.2 Capacitor Testing……………………………………………………………….53
7.3 MOSFET Testing…………………..………………………………………...53
7.4 DC motor Testing…………….……………………………………………54
(8) Advantages and Limitations ...................................................................................... 55
8.1 Advantages .............................................................................................................. 55
8.2 Limitations ........................................................................................................... 55
(9) Data sheet ..................................................................................................................... 56
9.1 Diode(1N4007) ........................................................................................................ 56
9.2 IC(Lm324) .......................................................................................................... 57
9.3 MOSFET(IRF840)…….…………………………………………………….59
(10) Daily schedule ............................................................................................................ 55
Daily schedule.….………………………………………………………………….61
Reference……………………………...……………………………………………62
Conclusion……………………………...…………………………………………..63
LIST OF FIGURES
Chapter
Topic Name Page Number
1.1
Weldor Industry
1
4.1
DC Motor Control Using PWM
10
4.3
Physical diagram
11
5.1(a)
Resistor
14
5.1(b)
Resistor symbol
15
5.2(a)
Capacitor
16
5.2(b)
Parallel plate of capacitor
18
5.3(a)
Construction of semiconductor diode
19
5.3(b)
Depletion region of semiconductor diode
19
5.3(c)
Diode bias voltage
20
5.3(d)
Reverse bias of diode
21
6.1
5.3(e)
Forward bias of diode
22
5.4(a)
Diagram of LED
23
5.4(b)
Figure of LED
25
5.4(c)
Working of LED
25
5.4(d)
Char. of LED
26
5.5
MOSFET
27
5.5(b)
Construction of MOSFET
30
5.5(c)
Construction of P&N channel MOSFET
30
5.5(d)
Structure of MOSFET
31
5.7(c)
Depletion mode of N channel MOSFET
33
5.7(d)
Enhancement mode N channel MOSFET
34
5.7(a)
Symbol of variable Resistor
39
5.7(b)
Variable Resistors
40
5.7(c)
Graph of Linear Resistance against Rotation
41
5.7(d)
Coated Potentiometer
42
5.7(e)
Potentiometers
43
PCB layout
49
LIST OF TABLES
Chapter
Topic Name Page Number
4.2
list of component table
10
5.1(c)
Resistor color coding table
16
5.6(b)
Pin description of LM324
38
9.1
maximum rating of diode
57
9.2
maximum rating of LM324
59
9.3
maximum rating of MOSFET
10.1
Daily schedule
60
62
ABSTRACT
In this project small DC motor are efficiently controlled using PWM methods.
In this project we use one IC which is LM324 which include four operational
amplifier two are used for triangular wave one for comparator.Op-amp N1, N2
&N3 are work as triangular wave generator, square wave generator and
comparator respectively. Op-amp N2 generates square wave and it fed to
inverting terminal of op-amp N1 which is integrate with input of non inverting
terminal and its output is given to non inverting terminal of N3 which compare
with inverting terminal. If it’s o/p is about +12v when voltage of inverting
terminal is greater than inverting terminal and it o/p is -12v when voltage of
inverting terminal is greater than non-inverting terminal.Finally, it’s o/p given
gate of n-channel MOSFET during positive half cycle it become ON otherwise
it become OFF and motor will rotate respect to o/p of MOSFET.
Chapter-1
Introduction
Introduction:
The project we have done is entailed LM324 IC and Variable register
with electronics application this is an industrial defined project i.e. IDP. And the
title is so given from the problem definition “speed control dc motor by use of
PWM”. We got the above mentioned problem definition from our industrial
visit to welder industry.
1.1
Industry visited:
For the industrial defined project I visited Weldor Industry Works
(Metoda). The industry is located in Metoda. The best part of this industry is the
beautiful environment and friendly atmosphere. The people working in this
industry are very genuine and down to earth. They co-operated on my visit to
this industry. And helped in every possible manner.
1.1 Weldor Industry
Weldor was founded in 1955 by Mr. Bharat Vaghela. The company adopted
advanced gear technology. Step by step gear shaping, hobblingand shaving and
finally added gear is grinding technology also. The company started
manufacturing 20 gears a day and today it is making 250 gears daily on the
automatic CNC machine. In last 4 years Mr. Ravi Vaghela, grandson of Mr.
Bharat Vaghela has become an added part of the company
Chapter 2
Problem definition
2.1 Detailed problem definition:
To understand the problem definition deeply we first need to know about
the CNC machine and the problem occurred in the machine.
2.1.1 CNC machine:It is necessary to know about the machine in which you are making our
project. Thus I have included the detailed description of the CNC machine in
which I m going to place my project.
What is CNC?
CNC stands for Computer Numerical Control and has been around since
the early 1970's. Prior to this, it was called NC, for Numerical Control. (In the
early 1970's computers were introduced to these controls, hence the name
change.)
While people in most walks of life have never heard of this term, CNC
has touched almost every form of manufacturing process in one way or another.
If you'll be working in manufacturing, it's likely that you'll be dealing with CNC
on a regular basis.
While there are exceptions to this statement, CNC machines typically
replace (or work in conjunction with) some existing manufacturing process/es.
Take one of the simplest manufacturing processes, drilling holes, for example.
A drill press can of course be used to machine holes. (It's likely that almost
everyone has seen some form of drill press, even if you don't work in
manufacturing.) A person can place a drill in the drill chuck that is secured in
the spindle of the drill press. They can then (manually) select the desired speed
for rotation (commonly by switching belt pulleys), and activate the spindle.
Then they manually pull on the quill lever to drive the drill into the work piece
being machined.
As you can easily see, there is a lot of manual intervention required to use
a drill press to drill holes. A person is required to do something almost every
step along the way! While this manual intervention may be acceptable for
manufacturing companies if but a small number of holes or work pieces must be
machined, as quantities grow, so does the likelihood for fatigue due to the
tediousness of the operation. And do note that we've used one of the simplest
machining operations (drilling) for our example. There are more complicated
machining operations that would require a much higher skill level (and increase
the potential for mistakes resulting in scrap work pieces) of the person running
the conventional machine tool. (We commonly refer to the style of machine that
CNC is replacing as the conventional machine.)
By comparison, the CNC equivalent for a drill press (possibly a CNC
machining center or CNC drilling & tapping center) can be programmed to
perform this operation in a much more automatic fashion. Everything that the
drill press operator was doing manually will now be done by the CNC machine,
including: placing the drill in the spindle, activating the spindle, positioning the
work piece under the drill, machining the hole, and turning off the spindle.
As you might already have guessed, everything that an operator would be
required to do with conventional machine tools is programmable with CNC
machines. Once the machine is setup and running, a CNC machine is quite
simple to keep running. In fact CNC operators tend to get quite bored during
lengthy production runs because there is so little to do. With some CNC
machines, even the work piece loading process has been automated. (We don't
mean to over-simplify here. CNC operators are commonly required to do other
things related to the CNC operation like measuring work pieces and making
adjustments to keep the CNC machine running good work pieces.)
Let's look at some of the specific programmable functions.
All CNC machine types share this commonality: They all have two or
more programmable directions of motion called axes. An axis of motion can be
linear (along a straight line) or rotary (along a circular path). One of the first
specifications that imply a CNC machine's complexity is how many axes it has.
Generally speaking, the more axes, the more complex the machine.
The axes of any CNC machine are required for the purpose of causing the
motions needed for the manufacturing process. In the drilling example, these (3)
axis would position the tool over the hole to be machined (in two axes) and
machine the hole (with the third axis). Axes are named with letters. Common
linear axis names are X, Y, and Z. Common rotary axis names are A, B, and C.
A CNC machine wouldn't be very helpful if all it could only move the work
piece in two or more axes. Almost all CNC machines are programmable in
several other ways. The specific CNC machine type has a lot to do with its
appropriate programmable accessories. Again, any required function will be
programmable on full-blown CNC machine tools. Here are some examples for
one machine type.
The CNC program
Think of giving any series of step-by-step instructions. A CNC program
is nothing more than another kind of instruction set. It's written in sentence-like
format and the control will execute it in sequential order, step by step.
A special series of CNC words are used to communicate what the
machine is intended to do. CNC words begin with letter addresses (like F for
federate, S for spindle speed, and X, Y & Z for axis motion). When placed
together in a logical method, a group of CNC words make up a command that
resemble a sentence. For any given CNC machine type, there will only be about
40-50 words used on a regular basis. So if you compare learning to write CNC
programs to learning a foreign language having only 50 words, it shouldn't seem
overly difficult to learn CNC programming.
The CNC control
The CNC control will interpret a CNC program and activate the series of
commands in sequential order. As it reads the program, the CNC control will
activate the appropriate machine functions, cause axis motion, and in general,
follow the instructions given in the program. Along with interpreting the CNC
program, the CNC control has several other purposes. All current model CNC
controls allow programs to be modified (edited) if mistakes are found. The CNC
control allows special verification functions (like dry run) to confirm the
correctness of the CNC program. The CNC control allows certain important
operator inputs to be specified separate from the program, like tool length
values. In general, the CNC control allows all functions of the machine to be
manipulated.
2.2 Problem in the machine:
While visiting Weldor industry I saw that speed control of dc motor in
other way but in that way I observed that it is difficult to handles the speed of
motor if load is increase and it loss more power compare with other but this
circuit is superior to using a fixed or variable resistor for heavy or varying
electrical loads, such as motor and LED.
Chapter 3
Feasibility
3.1 Financial feasibility:
The resources used in this project are quite feasible financially.
Components list:
 Resisters
 diode
 capacitor
 LM324 IC
 MOSFET
 Variable resister
The list of components given above shows that all the components are
cheap and feasible. The company will not have any problem in using this simple
project circuit.
3.2 Resource feasibility:
All the resources used in this project are easily available.
The LM324 IC used in this project might be difficult to find in the
market. But it is easily available from the dual supply.
3.3 Technical feasibility:
After I gave my idea to the industry person, the industry person
Told that my idea was quite feasible technically and promised to try it on his
Machines.
Thus the project is feasible technically but cannot be used on machines
directly because it needs some specifications and data of the machine to make
the project fit for machine.
But the industry I visited didn’t share the data of the machines and kept
them personal. They had some terms and conditions according to which I had
to work. And they didn’t give any detailed specifications of the machines and
they even didn’t allow working on their machines.
Chapter 4
Circuit Description
4.1 Circuit Diagram:
4.1 Fig. of D.C. Motor Control Using PWM
4.2 List of components:
SR NO.
Name of component
Quantity
1
DC MOTOR
1
2
IC-LM324
1
3
Capacitor
1
4
Resister
7
5
LED
1
6
MOSFET
1
7
Variable Resister
1
8
Diode
1
4.2 list of components of above circuit
4.3
Physical diagram:
4.3 Fig of physical circuit diagram
4.3.1
Operation:
Small DC motors are efficiently controlled using pulse-
width
modulation (PWM) method.
The circuit described here is built around an LM324 low-power
quad-operational amplifier. Of the four op-amps (operational amplifiers)
available in this IC, two are used for triangular wave generator and one
for comparator.
Op-amp N2 generates a 1.6kHz square wave, while op-amp N1 is
configured as an integrator.The square wave output of N2 at its pin 14 is
fed to the inverting input (pin 2) of N1 through resistor R1.
As N1 is configured as an integrator, it outputs a triangular wave of
the same frequency as the square wave.The triangular wave is fed to pin
5 of op-amp N3, which is configured as a comparator.The reference
voltage at pin 6 of the comparator is fixed through the potential divider
arrangement formed by pot meter VR1 and resistors R4 and R5.
It can be set from –6V (lowermost position of VR1) to +6v ( higher
most position of VR1).The triangular wave applied at pin 5 of N3 is
compared with the reference voltage at its pin 6.
The output at pin 7 is about +12V when the voltage at pin 5 is
greater than the voltage at pin 6.Similarly, the output at pin 7 is about 12V when the voltage at pin 5 is lower than the voltage at pin 6.
The output from comparator N3 is the gate voltage for n-channel
MOSFET (T1).
T1 switches on when the gate voltage is positive and switches off
when the gate voltage is negative. Setting of the reference voltage
therefore controls the pulse-width of the motor.
When T1 is switched on for a longer period, the pulse width will be
wider, which means more average DC component and faster speed of the
motor.
Speed will be low when the pulse width is small. Thus pot meter
VR1 controls the speed of the motor.Assemble the circuit on a generalpurpose PCB and enclose in a suitable cabinet. The circuit requires ±12V
power supply for its working.
It can also be modified to control the speed of a 6V or 24V DC
motor
Chapter 5
Components detail
Component details:
5.1 Resistor:
Register is a passive element. These components are split into two
categories; those which dissipate energy and those which store it. The property
of a substance, which opposes the flow of an electrical current through it, is
called the “resistance” (measured in ohms). Fixed resisters are used in circuit
diagram.
A linear resistor is a linear, passive two-terminal electrical component
that implements electrical resistance as a circuit element. The current through a
resistor is in direct proportion to the voltage across the resistor's terminals.
Thus, the ratio of the voltage applied across a resistor's terminals to the intensity
of current through the circuit is called resistance. This relation is represented by
Ohm's law:
Resistors are common elements of electrical networks and electronic
circuits and are ubiquitous in most electronic equipment. Practical resistors can
be made of various compounds and films, as well as resistance wire (wire made
of a high-resistivity alloy, such as nickel-chrome). Resistors are also
implemented within integrated circuits, particularly analog devices, and can also
be integrated into hybrid and printed circuits.
The electrical functionality of a resistor is specified by its resistance:
common commercial resistors are manufactured over a range of more than nine
orders of magnitude. When specifying that resistance in an electronic design,
the required precision of the resistance may require attention to the
manufacturing tolerance of the chosen resistor, according to its specific
application.
The temperature coefficient of the resistance may also be of concern in
some precision applications. Practical resistors are also specified as having a
maximum power rating which must exceed the anticipated power dissipation of
that resistor in a particular circuit: this is mainly of concern in power electronics
applications. Resistors with higher power ratings are physically larger and may
require heat sinks. In a high-voltage circuit, attention must sometimes be paid to
the rated maximum working voltage of the resistor.
Practical resistors have a series inductance and a small parallel
capacitance; these specifications can be important in high-frequency
applications. In a low-noise amplifier or pre-amp, the noise characteristics of a
resistor may be an issue. The unwanted inductance, excess noise, and
temperature coefficient are mainly dependent on the technology used in
manufacturing the resistor. They are not normally specified individually for a
particular family of resistors manufactured using a particular technology.
A family of discrete resistors is also
characterized according to its form factor,
that is, the size of the device and the position
of its leads (or terminals) which is relevant in
the practical manufacturing of circuits using
them.
Fig. 5.1(a)of resistors
The symbol for a resistor is shown in the below.
Fig.5.1(b) : Resistor symbols
The unit for measuring resistance is the OHM. (The Greek letter Ω called Omega). Higher resistance values are represented by "k" (kilo-ohms) and
M (Meg ohms).
5.1.1 Resistor Markings:Resistance value is marked on the resistor body. Most resistors have 4
bands. The first two bands provide the numbers for the resistance and the third
band provides the number of zeros. The fourth band indicates the tolerance.
Tolerance values of 5%, 2%, and 1% are most commonly available.
The following table shows the colors used to identify resistor values:
COLOR DIGIT MULTIPLIER TOLERANCE
TC
±10%
Silver
x 0.01 
±5%
Gold
x 0.1 
0
Black
x1
1
±1%
±100*10-6/K
Brown
x 10 
2
±2%
±50*10-6/K
Red
x 100 
3
±15*10-6/K
Orange
x 1 k
4
±25*10-6/K
Yellow
x 10 k
5
±0.5%
Green
x 100 k
6
±0.25%
±10*10-6/K
Blue
x 1 M
7
±0.1%
±5*10-6/K
Violet
x 10 M
8
Grey
x 100 M
9
±1*10-6/K
White
x 1 G
Fig. 5.1(c): Four-band resistor, c. Five-band resistor, d. Cylindrical SMD
resistor, e. Flat SMD resistor
5.2 Capacitor:
Fig5.2(a) Capacitor
A capacitor (formerly known as condenser) is a passive two-terminal
electrical component used to store energy in an electric field. The forms of
practical capacitors vary widely, but all contain at least two electrical
conductors separated by a dielectric (insulator); for example, one common
construction consists of metal foils separated by a thin layer of insulating film.
Capacitors are widely used as parts of electrical circuits in many common
electrical devices.
When there is a potential difference (voltage) across the conductors, a
static electric field develops across the dielectric, causing positive charge to
collect on one plate and negative charge on the other plate. Energy is stored in
the electrostatic field. An ideal capacitor is characterized by a single constant
value, capacitance, measured in farads. This is the ratio of the electric charge on
each conductor to the potential difference between them.
The capacitance is greatest when there is a narrow separation between
large areas of conductor; hence capacitor conductors are often called "plates,"
referring to an early means of construction. In practice, the dielectric between
the plates passes a small amount of leakage current and also has an electric field
strength limit, resulting in a breakdown voltage, while the conductors and leads
introduce an undesired inductance and resistance.Capacitors are widely used in
electronic circuits for blocking direct current while allowing alternating current
to pass, in filter networks, for smoothing the output of power supplies, in the
resonant circuits that tune radios to particular frequencies and for many other
purposes.
The simplest capacitor consists of two parallel conductive plates
separated by a dielectric with permittivity ε (such as air). The model may also
be used to make qualitative predictions for other device geometries. The plates
are considered to extend uniformly over an area A and a charge density ±ρ =
±Q/A exists on their surface. Assuming that the width of the plates is much
greater than their separation d, the electric field near the centre of the device
will be uniform with the magnitude E = ρ/ε. The voltage is defined as the line
integral of the electric field between the plates.Solving this for C = Q/V reveals
that capacitance increases with area and decreases with separation
…………………………..(1)
The capacitance is therefore greatest in devices made from materials with
a high permittivity, large plate area, and small distance between plates.
We see that the maximum energy is a function of dielectric volume,
permittivity, and dielectric strength per distance. So increasing the plate area
while decreasing the separation between the plates while maintaining the same
volume has no change on the amount of energy the capacitor can store. Care
must be taken when increasing the plate separation so that the above assumption
of the distance between plates being much smaller than the area of the plates is
still valid for these equations to be accurate.
Fig 5.2(b) parallel plates of capacitor
5.3 Diode:
5.3.1 Diode Construction:
Fig 5.3(a) construction of semiconductor diode
A diode is formed by joining two equivalently doped P-Type and N-Type
semiconductor. When they are joined an interesting phenomenon takes place.
The P-Type semiconductor has excess holes and is of positive charge. The NType semiconductor has excess electrons. At the point of contact of the P-Type
and N-Type regions, the holes in the P-Type attract electrons in the N-Type
material. Hence the electron diffuses and occupies the holes in the P-Type
material.
Causing a small region of the N-type near the junction to loose electrons
and behaves like intrinsic semiconductor material, in the P-type a small region
gets filled up by holes and behaves like a intrinsic semiconductor.
Fig 5.3(b) Depletion region of semiconductor diode
Thin intrinsic region is called depletion layer, since its depleted of charge (see
diagram above) and hence offers high resistance. It’s this depletion region that
prevents the further diffusion of majority carriers. In physical terms the size of
the depletion layer is very thin.
5.3.2 Diode Biased Voltage
Zero Bias:
Fig. 5.3(c) Diode Biased Voltage
When a diode is zero biased, that is has no bias, it just stays. Almost no
current passes through the diode. However if you connect the anode and
cathode of the diode you might be able to observe small voltage or current that
is insignificant. This is because the electromagnetic spectrum that's present in
our environment by default (microwave background, heat, light, radio waves)
knocks off electrons in the semiconductor lattice that constitutes current. For
practical reasons this current can be considered zero.
Reverse Bias:-
Fig. 5.3(d) Reverse bias of diode
In reverse bias the P-type region is connected to negative voltage and Ntype is connected to positive terminal as shown above. In this condition the
holes in P-type gets filled by electrons from the battery / cell (in other words the
holes get sucked out of the diode).
The electron in N-type material is sucked out of the diode by the positive
terminal of the battery. So the diode gets depleted of charge.
So initially the depletion layer widens (see image above) and it occupies
the entire diode. The resistance offered by the diode is very huge. The current
that flows in reverse bias is only due to minority charge which is in nano
amperes in silicon and micro amperes in high power silicon and germanium
diodes.
Forward Bias:-
Fig. 5.3(e) Forward Bias of diode
In forward bias the P-Region of the diode is connected with the positive
terminal of the battery and N-region is connected with the negative region.
During the forward bias the following process occurs.
The positive of the battery pumps more holes into the P-region of the
diode. The negative terminal pumps electrons into the N-region
The excess of charge in P and N region will apply pressure on the
depletion region and will make it shrink. As the voltage increases the depletion
layer will become thinner and thinner and hence diode will offer lesser and
lesser resistance. Since the resistance decreases the current will increase (though
not proportional) to the voltage.
At one particular voltage level Vf called the threshold / firing / cut-off
voltage the depletion layer disappears (overwhelmed by the charge) and hence
from this point on the diode starts to conduct very easily. From this point on the
diode current increases exponentially to the voltage applied.
5.4 LED:
A light-emitting diode (LED) is a semiconductor light source. LEDs are
used as indicator lamps in many devices and are increasingly used for other
lighting. Introduced as a practical electronic component in 1962, early LEDs
emitted low-intensity red light, but modern versions are available across the
visible, ultraviolet, and infrared wavelengths, with very high brightness.
When a light-emitting diode is forward-biased (switched on), 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 gap of the semiconductor. LEDs are often small in area (less than
1 mm2), and integrated optical components may be used to shape its radiation
pattern.
Fig. 5.4(a)Diagram of LED
LEDs present many advantages over incandescent light sources including
lower energy consumption, longer lifetime, improved robustness, smaller size,
and faster switching. LEDs powerful enough for room lighting are
relativelyexpensive and require more precise current and heat management than
compact fluorescent lamp sources of comparable output.
Light-emitting diodes are used in applications as diverse as replacements
for aviation lighting, automotive lighting (in particular brake lamps, turn
signals, and indicators) as well as in traffic signals. LEDs have allowed new
text, video displays, and sensors to be developed, while their high switching
rates are also useful in advanced communications technology.
Infrared LEDs are also used in the remote control units of many
commercial products including televisions, DVD players, and other domestic
appliances.
Practical use:
The first commercial LEDs were commonly used as replacements for
incandescent and neon indicator lamps, and in seven-segment displays, first in
expensive equipment such as laboratory and electronics test equipment, then
later in such appliances as TVs, radios, telephones, calculators, and even
watches (see list of signal uses).
These red LEDs were bright enough only for use as indicators, as the
light output was not enough to illuminate an area. Readouts in calculators were
so small that plastic lenses were built over each digit to make them legible.
Later, other colors grew widely available and also appeared in appliances and
equipment. As LED materials technology grew more advanced, light output
rose, while maintaining efficiency and reliability at acceptable levels.
The invention and development of the high-power white-light LED to use
for illumination, which is fast replacing incandescent and fluorescent lighting.
(See list of illumination applications).
Most LEDs were made in the very common 5 mm T1¾ and 3 mm T1
packages, but with rising power output, it has grown increasingly necessary to
shed excess heat to maintain reliability, so more complex packages have been
adapted for efficient heat dissipation. Packages for state-of-the-art high-power
LEDs bear little resemblance to early LEDs.
Fig.5.4(b) LED
Working of LED
The LED consists of a chip of semiconducting material doped with
impurities to create ap-n junction. As in other diodes, current flows easily from
the p-side, oranode, to the n-side, orcathode, but not in the reverse direction.
Charge-carriers electronsand holes — flow into the junction from electrodes
with different voltages. When an electron meets a hole, it falls into a lower
energy level, and releases energyin the form of aphoton.
Fig.5.4(c)Inner workings of LED
The wavelengthof the light emitted, and thus its color depends on the
band gap energy of the materials forming the p-n junction. In silicon or
germanium diodes, the electrons and holes recombine by a non-radiative
transition, which produces no optical emission, because these areindirect band
gapmaterials. The materials used for the LED have a direct band gap with
energies corresponding to near-infrared, visible, or near-ultraviolet light.
Fig 5.4(d) diagram for adiode. An LED will begin to emit light when the onvoltage is exceeded. Typical on voltages are 2–3 volts.
LED development began with infrared and red devices made with gallium
arsenide. Advances in materials science have enabled making devices with
ever-shorter wavelengths, emitting light in a variety of colors.
LEDs are usually built on an n-type substrate, with an electrode attached
to the p-type layer deposited on its surface. P-type substrates, while less
common, occur as well. Many commercial LEDs, especially GaN/InGaN, also
use sapphire substrate.
Most materials used for LED production have very high refractive
indices. This means that much light will be reflected back into the material at
the material/air surface interface. Thus, light extraction in LEDs is an important
aspect of LED production, subject to much research and development.
5.5 MOSFET:
MOSFETs come in four different types. They may be enhancement or
depletion mode, and they may be n-channel or p-channel. For this application
we are only interested in n-channel enhancement mode MOSFETs, and these
will be the only ones talked about from now on. There are also logic-level
MOSFETs and normal MOSFETs . The only difference between these is the
voltage level required on the gate.
Fig 5.5(a) N-Channel Enhancement mode IGFET (a)physical symbol
, (b) Symbol.(c)Construction
Unlike bipolar transistors that are basically current-driven devices,
MOSFETs are voltage-controlled power devices. If no positive voltage is
applied between gate and source the MOSFET is always non-conducting. If we
apply a positive voltage UGS to the gate we'll set up an electrostatic field
between it and the rest of the transistor.
Fig. 5.5(b) Construction of MOSFET
The positive gate voltage will push away the 'holes' inside the p-type
substrate and attracts the moveable electrons in the n-type regions under the
source and drain electrodes. This produces a layer just under the gate's insulator
through which electrons can get into and move along from source to drain.
The positive gate voltage therefore 'creates' a channel in the top layer of
material between oxide and p-Si. Increasing the value of the positive gate
voltage pushes the p-type holes further away and enlarges the thickness of the
created channel.
As a result we find that the size of the channel we've made increases with
the size of the gate voltage and enhances or increases the amount of current
which can go from source to drain- this is why this kind of transistor is called an
enhancement mode device.
5.5.1 The Metal Oxide FET – MOSFET:
As well as the Junction Field Effect Transistor (JFET), there is another
type of Field Effect Transistor available whose Gate input is electrically
insulated from the main current carrying channel and is therefore called an
Insulated Gate Field Effect Transistor or IGFET.
The most common type of insulated gate FET which is used in many
different types of electronic circuits is called the Metal Oxide Semiconductor
Field Effect Transistor or MOSFET for short.
The IGFET or MOSFET is a voltage controlled field effect transistor
that differs from a JFET in that it has a "Metal Oxide" Gate electrode which is
electrically insulated from the main semiconductor N-channel or P-channel by a
thin layer of insulating material usually silicon dioxide (commonly known as
glass).
This insulated metal gate electrode can be thought of as one plate of a
capacitor. The isolation of the controlling Gate makes the input resistance of the
MOSFET extremely high in the Mega-ohms (MΩ) region thereby making it
almost infinite.
As the Gate terminal is isolated from the main current carrying channel
"NO current flows into the gate" and just like the JFET, the MOSFET also acts
like a voltage controlled resistor were the current flowing through the main
channel between the Drain and Source is proportional to the input voltage. Also
like the JFET, this very high input resistance can easily accumulate large
amounts of static charge resulting in the MOSFET becoming easily damaged
unless carefully handled or protected.
Like the previous JFET tutorial, MOSFETs are three terminal devices
with a Gate, Drain and Source and both P-channel (PMOS) and N-channel
(NMOS) MOSFETs are available. The main difference this time is that
MOSFETs are available in two basic forms:

1. Depletion Type - the transistor requires the Gate-Source voltage, (
VGS ) to switch the device "OFF". The depletion mode MOSFET is
equivalent to a "Normally Closed" switch.

2. Enhancement Type - the transistor requires a Gate-Source voltage, (
VGS ) to switch the device "ON". The enhancement mode MOSFET is
equivalent to a "Normally Open" switch.
Fig 5.5(c) construction of P-type& N-type channel MOSFET
The four MOSFET symbols above show an additional terminal called the
Substrate and is not normally used as either an input or an output connection but
instead it is used for grounding the substrate. It connects to the main semi
conductive channel through a diode junction to the body or metal tab of the
MOSFET. Usually in discrete type MOSFETs, this substrate lead is connected
internally to the source terminal. When this is the case, as in enhancement types
it is omitted from the symbol for clarification.
The line between the drain and source connections represents the semi
conductive channel. If this is a solid unbroken line then this represents a
"Depletion" (normally closed) type MOSFET and if the channel line is shown
dotted or broken it is an "Enhancement" (normally open) type MOSFET. The
direction of the arrow indicates either a P-channel or an N-channel device.
Basic MOSFET Structure and Symbol
Fig 5.5(d) structure of MOSFET
The construction of the Metal Oxide Semiconductor FET is very different
to that of the Junction FET. Both the Depletion and Enhancement type
MOSFETs use an electrical field produced by a gate voltage to alter the flow of
charge carriers, electrons for N-channel or holes for P-channel, through the
semiconductive drain-source channel.
The gate electrode is placed on top of a very thin insulating layer and
there are a pair of small N-type regions just under the drain and source
electrodes.
We saw in the previous tutorial, that the gate of a JFET must be biased in
such a way as to reverse-bias the PN-junction but with a insulated gate
MOSFET device no such limitations apply so it is possible to bias the gate of a
MOSFET in either polarity, +ve or -ve.
This makes MOSFETs especially valuable as electronic switches or to
make logic gates because with no bias they are normally non-conducting and
this high gate input resistance means that very little or no control current is
needed as MOSFETs are voltage controlled devices. Both the P-channel and the
N-channel MOSFETs are available in two basic forms, the Enhancement type
and the Depletion type.
5.5.2 Depletion-mode MOSFET:
The Depletion-mode MOSFET, which is less common than the
enhancement types is normally switched "ON" without the application of a gate
bias voltage making it a "normally-closed" device. However, a gate to source
voltage ( VGS ) will switch the device "OFF".
Similar to the JFET types. For an N-channel MOSFET, a "positive" gate
voltage widens the channel, increasing the flow of the drain current and
decreasing the drain current as the gate voltage goes more negative. In other
words, for an N-channel depletion mode MOSFET: +VGS means more electrons
and more current.
While a -VGS means less electrons and less current. The opposite is also
true for the P-channel types. Then the depletion mode MOSFET is equivalent to
a "normally-closed" switch.
Depletion-mode N-Channel MOSFET and circuit Symbols
Fig 5.5.2 (a) Depletion-mode N-Channel MOSFET and circuit Symbols
The depletion-mode MOSFET is constructed in a similar way to their
JFET transistor counterparts were the drain-source channel is inherently
conductive with the electrons and holes already present within the N-type or Ptype channel. This doping of the channel produces a conducting path of low
resistance between the Drain and Source with zero Gate bias.
5.5.3 Enhancement-mode MOSFET:
The more common Enhancement-mode MOSFET is the reverse of the
depletion-mode type. Here the conducting channel is lightly doped or even
untapped making it non-conductive. This results in the device being normally
"OFF" when the gate bias voltage is equal to zero.
A drain current will only flow when a gate voltage ( VGS ) is applied to
the gate terminal greater than the threshold voltage ( VTH ) level in which
conductance takes place making it a transconductance device.
This positive +ve gate voltage pushes away the holes within the channel
attracting electrons towards the oxide layer and thereby increasing the thickness
of the channel allowing current to flow. This is why this kind of transistor is
called an enhancement mode device as the gate voltage enhances the channel.
Increasing this positive gate voltage will cause the channel resistance to
decrease further causing an increase in the drain current, ID through the channel.
In other words, for an N-channel enhancement mode MOSFET: +VGS turns the
transistor "ON", while a zero or -VGS turns the transistor "OFF". Then, the
enhancement-mode MOSFET is equivalent to a "normally-open" switch.
Enhancement-mode N-Channel MOSFET and circuit Symbols:
Fig 5.5.3 (b) Enhancement-mode N-Channel MOSFET and circuit Symbols
Enhancement-mode MOSFETs make excellent electronics switches due
to their low "ON" resistance and extremely high "OFF" resistance as well as
their infinitely high gate resistance. Enhancement-mode MOSFETs are used in
integrated circuits to produce CMOS type Logic Gates and power switching
circuits in the form of as PMOS (P-channel) and NMOS (N-channel) gates.
CMOS actually stands for Complementary MOS meaning that the logic device
has both PMOS and NMOS within its design.
FEATURES:
·Drain Current –ID=8.0A@ TC=25℃
·Drain Source Voltage: VDSS= 500V(Min)
·Static Drain-Source On-Resistance: RDS(on) = 0.85Ω(Max)
5.5.4MOSFET Summary:
The Metal Oxide Semiconductor Field Effect Transistor, or MOSFET
for short, has an extremely high input gate resistance with the current flowing
through the channel between the source and drain being controlled by the gate
voltage. Because of this high input impedance and gain, MOSFETs can be
easily damaged by static electricity if not carefully protected or handled.
MOSFET's are ideal for use as electronic switches or as common-source
amplifiers as their power consumption is very small. Typical applications for
metal oxide semiconductor field effect transistors are in Microprocessors,
Memories, Calculators and Logic CMOS Gates etc.
Also, notice that a dotted or broken line within the symbol indicates a
normally "OFF" enhancement type showing that "NO" current can flow through
the channel when zero gate-source voltage VGS is applied. A continuous
unbroken line within the symbol indicates a normally "ON" Depletion type
showing that current "CAN" flow through the channel with zero gate voltage.
For
P-channel types the symbols are exactly the same for both types except
that the arrow points outwards. This can be summarized in the following
switching table.
MOSFET type
VGS = +ve VGS = 0 VGS = -ve
N-Channel Depletion
ON
ON
OFF
N-Channel Enhancement
ON
OFF
OFF
P-Channel Depletion
OFF
ON
ON
P-Channel Enhancement
OFF
OFF
ON
5.5.4 Modes of FET
So for N-channel enhancement type MOSFETs, a positive gate voltage turns
"ON" the transistor and with zero gate voltage, the transistor will be "OFF". For
a P-channel enhancement type MOSFET, a negative gate voltage will turn "ON"
the transistor and with zero gate voltage; the transistor will be "OFF".
The voltage point at which the MOSFET starts to pass current through the
channel is determined by the threshold voltage VTH of the device and is typical
around 0.5V to 0.7V for an N-channel device and -0.5V to -0.8V for a Pchannel device.
In the next tutorial about Field Effect Transistors instead ofthe operation
of the transistor in its saturation and cut-off regions when used as a solid-state
switch.
Field effect transistor switches are used in many applications to switch a
DC current "ON" or "OFF" such as LED’s which require only a few milliamps
at low DC voltages, or motors which require higher currents at higher voltages.
5.6IC LM324:
LM324 is a 14pin IC consisting of four independent operational
amplifiers (op-amps) compensated in a single package. Op-amps are high gain
electronic voltage amplifier with differential input and, usually, a single-ended
output. The output voltage is many times higher than the voltage difference
between input terminals of an op-amp.
These op-amps are operated by a single power supply LM324 and need
for a dual supply is eliminated. They can be used as amplifiers, comparators,
oscillators, rectifiers etc. The conventional op-amp applications can be more
easily implemented with LM324.
Pin Diagram:
Fig 5.6(a)Pin Diagram of LM324.
Pin Description:
Pin
Function
Name
1
Output of 1st comparator
Output 1
2
Inverting input of 1st comparator
Input 1-
3
Non-inverting input of 1st comparator
Input 1+
4
Supply voltage; 5V (up to 32V)
Vcc
5
Non-inverting input of 2nd comparator
Input 2+
6
Inverting input of 2nd comparator
Input 2-
7
Output of 2nd comparator
Output 2
8
Output of 3rd comparator
Output 3
9
Inverting input of 3rd comparator
Input 3-
10
Non-inverting input of 3rd comparator
Input 3+
11
Ground (0V)
Ground
12
Non-inverting input of 4th comparator
Input 4+
13
Inverting input of 4th comparator
Input 4-
14
Output of 4th comparator
Output 4
No
5.6(b) Pin Description Table
5.7 Variable Resistors:
These are resistors whose resistance can be altered and they have three
connections. There are two connections at either end of the resistance material,
which is commonly known as the track. The third connection is made to a
conducting slider, commonly known as the wiper, which is in contact with the
track and can be slid along it from one end to the other. The current or voltage
available at the wiper is then related to the position that it has along the track.
Symbol:
Fig 5.7(a) symbol of variable Resistor
Variable Resistors can be used in a circuit to alter resistance and in this
situation only two connections are used. One end and the wiper. It is good
practice to connect the free end to the wiper so in the event that the wiper fails
to connect, the variable resistor will go to maximum resistance protecting the
circuit.
Potentiometer or Pot is the name given when the variable resistor is used
as a Potential Divider to alter voltage in part of the circuit from 9 to 0 volts or
as a speaker balance control. All three connections are used.
Turn the Potentiometer shaft clockwise and anti-clockwise and see how
the voltages change from 0 to 9 volts.
Fig. 5.7(b) Variable Resistors
There are two types of variable resistors:
1. Preset:The resistance of part of the circuit needs to be adjusted once during
manufacture to allow for component variations. Presets are soldered directly
onto the Printed Circuit Board. (PCB)
Fig(a) Pre Set
2. Control:The resistance of part of the circuit is altered frequently such as volume
control. These are available as single gang, double gang (stereo volume) and
single gang switched. They are available as either rotary shaft or slider.
Fig (b)Rotary Control
Fig (c) Slide Control
Values of Variable Resistors:Typical values:- 100R 220R 470R 1K 2K2 4K7 10K 22K 47K
100K
220K
470K
1M
Resistance is available in two forms:- Linear and Log values.
Linear values change directly with the amount of movement giving a
straight line on the graph. Log values start off with a small change in resistance
for a large movement and gradually alters to a large change in resistance for a
small amount of movement. Curved line on the graph.
Fig 5.7(c)Graph of Linear and Log Resistance values against Rotation
5.7.1 Potentiometers:
Potentiometers (also called pots) are variable resistors, used as voltage or
current regulators in electronic circuits. By means of construction, they can be
divided into 2 groups: coated and wire-wound.
With coated potentiometers, (figure 1.6a), insulator body is coated with a
resistive material. There is a conductive slider moving across the resistive layer,
increasing the resistance between slider and one end of pot, while decreasing
the resistance between slider and the other end of pot.
Fig 5.7.1(d): Coated potentiometer
Wire-wound potentiometers are made of conductor wire coiled around
insulator body. There is a slider moving across the wire, increasing the
resistance between slider and one end of pot, while decreasing the resistance
between slider and the other end of pot.
Coated pots are much more common. With these, resistance can be linear,
logarithmic, inverse-logarithmic or other, depending upon the angle or position
of the slider. Most common are linear and logarithmic potentiometers, and the
most common applications are radio-receivers, audio amplifiers, and similar
devices where pots are used for adjusting the volume, tone, balance, etc.
Wire-wound potentiometers are used in devices which require more
accuracy in control. They feature higher dissipation than coated pots, and are
therefore in high current circuits.
Potentiometer resistance is commonly of E6 series, including the values:
1, 2.2 and 4.7. Standard tolerance values include 30%, 20%, 10% (and 5% for
wire-wound pots).
Potentiometers come in many different shapes and sizes, with wattage
ranging from 1/4W (coated pots for volume control in amps, etc) to tens of
watts (for regulating high currents). Several different pots are shown in the
photo 5.7.b, along with the symbol for a potentiometer.
Fig. 5.7.1(b): Potentiometers
The upper model represents a stereo potentiometer. These are actually
two pots in one casing, with sliders mounted on shared axis, so they move
simultaneously. These are used in stereophonic amps for simultaneous
regulation of both left and right channels, etc.
Lower left is the so called slider potentiometer. Lower right is a wirewound pot with a wattage of 20W, commonly used as rheostat (for regulating
current while charging a battery etc).
For circuits that demand very accurate voltage and current values,
trimmer potentiometers (or just trim pots) are used. These are small
potentiometers with a slider that is adjusted via a screwdriver.
Trim pots also come in many different shapes and sizes, with wattage
ranging from 0.1W to 0.5W. Image 5.7.c shows several different trim pots,
along with the symbol.
Fig. 5.7.1(c): Trim potentiometers
Resistance adjustments are made via a screwdriver. Exception is the trim
pot on the lower right, which can be adjusted via a plastic shaft. Particularly fine
adjusting can be achieved with the trim pot in the plastic rectangular casing
(lower middle). Its slider is moved via a screw, so that several full turns is
required to move the slider from one end to the other.
5.7.2 Practical examples with potentiometers:
As previously stated, potentiometers are most commonly used in amps,
radio and TV receivers, cassette players and similar devices. They are used for
adjusting volume, tone, balance, etc.
As an example, we will analyze the common circuit for tone regulation in
an audio amp. It contains two pots and is shown in the figure 5.7.d.
Fig. 5.7.2(a) Tone regulation circuit: a. Electrical scheme, b. Function of
amplification
Potentiometer marked BASS regulates low frequency amplification.
When the slider is in the lowest position, amplification of very low frequency
signals (tens of Hz) is about ten times greater than the amplification of mid
frequency signals (~kHz). If slider is in the uppermost position, amplification of
very low frequency signals is about ten times lower than the amplification of
mid frequency signals. Low frequency boost is useful when listening to music
with a beat (disco, jazz, R&B...), while Low Frequency amplification should be
reduced when listening to speech or classical music.
Similarly, potentiometer marked TREBLE regulates high frequency
amplification. High frequency boost is useful when music consists of highpitched tones such as chimes, while for example High Frequency amplification
should be reduced when listening to an old record to reduce the background
noise.
Diagram 5.7.2(a).Shows the function of amplification depending upon the
signal frequency. If both sliders are in their uppermost position, the result is
shown with curve 1-2. If both are in mid position function is described with line
3-4, and with both sliders in the lowest position, the result is shown with curve
5-6. Setting the pair of sliders to any other possible results in curves between
curves 1-2 and 5-6.
Potentiometers BASS and TREBLE are coated by construction and linear
by resistance.The third pot in the diagram is a volume control. It is coated and
logarithmic by resistance (hence the mark log)
Chapter 6
Project design
6.1 Software design:
I found my DC motor speed control using PWM circuit from the internet
as I said in the above chapter.I have made my complete project on a special
purpose PCB.
I prepared the layout of both of these circuits using dip trace software.I
learned dip trace software in my college. Then I installed the software from the
internet and started working on it. Given below is he detailed description on dip
trace software.
6.1.1 Dip trace:
Dip Trace is EDA software for creating schematic diagrams and printed
circuit boards. The first version of Dip Trace was released in August, 2004. The
latest version as of September 2011 is Dip Trace version 2.2. Interface has been
translated to many languages and new language can be added by user. There are
tutorials in English, Czech, Russian and Turkish. Starting from February 2011
Dip Trace is used as project publishing standard by Parallax.
Modules

Schematic Design Editor

PCB Layout Editor

Component Editor

Pattern Editor

Shape-Based Auto router

3D PCB Preview
Freeware and Non-Profit versions
A version of Dip Trace that is freely available with all the functionality of
the full package except it is limited to 300 pins and 2 signal layers.
Other sources

Dip Trace at Seattle Robotics Society meeting

Dip Trace at Nuts and Volts – October 2006

Review at C Net
Some hobby and educational groups such as the PICAXE forum members
have developed libraries specific to the PICAXE range of microcontroller as
produced by Revolution Education including many of the frequently used
associated integrated circuits. PICAXE related libraries can be found here:
 DIP TRACE Libraries by and for PICAXE microcontroller users
External links

Dip Trace official Website in English

Dip Trace Website in Italian

Dip Trace Website in Turkish

Novarm Ltd. Official Website in English
6.2 Hardware design:
The hard\ware design of both the circuit of the project i.e. DC motor
speed control using PWM circuit include their block diagrams and list of the
components used in these circuits.
PCB Layout:
Fig 6.1 PCB Layout
6.2.1 PCB designing steps:
The most important requirement of this project was to build a PCB with
minimum weight and size.
A zero PCB is a drilled board drilling process removes a lot of material
from board, and the weight is reduced. Designing method is as follows.
1. Decide proper places for components.
2. Actual placement of component on zero PCB.
3. Connecting tracks with solid wires.
4. Testing for continuity and debugging.
One PCB designed in this project. PCB are constructed on simple zero
PCB and interconnection of components was done by single stander wire.
PCB MANUFACTYRING:
STEP 1 (MASTER ART WORK)
Draw the master art work. It may be drawn 4 to 30 times larger than its final
expected size of the board
STEP 2 (NEGATIVE PHOTOGRAPHY)
Obtain negative photography of the master art work reduced to the final size
STEP 3 (CLEAN OF LAMINATE)
Clean the copper clad laminate using solvent like Tri Color ethylene
STEP 4 (COATING OF LAMINATE)
cost the laminate with photosensitive resist keep it nearly in a vertical position
for drying at room temperature(minimum for 5 min)
STEP 5 (EXPOSURE)
The resist coated laminate in contact with master art negative to be expose to
UV radiation in UV printer (apprx.5-6 min).
STEP 6 (DEVELOPING)
Immerse the exposed copper clad laminate in photo resist developer for 60-90
sec. remove the board and dry thoroughly
STEP 7 (DRYING THE IMAGE)
Immerses the board into the for about 10-20 sec. remove the board and wash it
under spray of water.
STEP 8 (ETCHING)
Immerse the board in FeCl3 solution (40-60 in) for etching unwanted copper
portion.
STEP 9 (RESIST REMOVER)
Wash the board under running water and remove the resist from image area
with solvent like Tri Chloral Ethylene.
STEP 10 (DRILLING)
Drill the fabricated PCB for mounting component.
STEP 11 (TINNING)
The solder in the tinning machine is heated up starting from 159 degree to 300
degree Celsius. When the solder gets heated properly, put the PCB in. The rack
and rotate the handle.
Chapter 7
Component Testing
7.1 RESISTER TESTING:
1. Select the appropriate function button from multimeter.
2. Select the required range scale on rotary switch.
3. Place the resister between terminals of meter.
4. Observe and note the reading.
5. LCR meter can also be used for this purpose.
NOTE:- WE CAN ALSO KNOW THE RESISTER BY THE COLORSOF THE
RESISTER
4 Band Resister Color Codes:COLOR
Silver
Gold
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Grey
White
DIGIT
MULTIPLIER TOLERANCE
±10%
x 0.01 
±5%
x 0.1 
0
x1
1
±1%
x 10 
2
±2%
x 100 
3
x 1 k
4
x 10 k
5
±0.5%
x 100 k
6
±0.25%
x 1 M
7
±0.1%
x 10 M
8
x 100 M
9
x 1 G
Table 7.1(a) Band Resister Color Codes:-
The Formula For Four Band Resistor:1.
(First Band + Second Band) * Third Band = Total
TC
±100*10-6/K
±50*10-6/K
±15*10-6/K
±25*10-6/K
±10*10-6/K
±5*10-6/K
±1*10-6/K
7.2 CAPACITOR TESTING:
1. Select the appropriate function button from multimeter.
2. Select the required range scale on rotary switch.
3. Place the capacitor between terminals of meter.
4. The capacitor voltage will appear on the screen and suddenly start
Decreasing due to discharging of this capacitor.
5. LCR meter can also be used for this purpose.
7.3 MOSFET TESTING:
1. Get a multimeter with a diode test range.
2. Connect the meter negative to the MOSFET's source.
3. Hold the MOSFET by the case or the tab if you wish, it doesn't matter
if you touch the metal body but be careful not to touch the leads until
you need to. Do NOT allow a MOSFET to come in contact with your
clothes, plastic or plastic products, etc. because of the high static
voltages it can generate.
4. First touch the meter positive on to the gate.
5. Now move the positive meter probe to the drain. You should get a low
reading. The MOSFET's gate capacitance has been charged up by the
meter and the device is turned on.
6. With the meter positive still connected to the drain, touch a finger
between source and gate (and drain if you wish, it doesn't matter). The
gate will be discharged through your finger and the meter reading
should go high, indicating a non-conducting device.
7.4 DC MOTOR TESTING:
Dc motor used in this project is 12v DC motor which is tested by using
digital contact-less tachometer arrangement was made so that the sensing circuit
gives high to low pulse for each completion of revolution
By measuring the time difference between two successive pulses RPS can
be calculated which further provide RPS value, as show below.
Power supply given to DC motor = 9v
Time interval between two successive pulses as seen on CRO = 30.4ms
 RPS = 1/(30.4ms)
=32.89
 RPS = 32
 RPM = 33 * 60
 RPM = 1975
Chapter 8
Advantages and Limitations
8.1
Advantages:
 I hope this article has shown you how easy it can be control speed,
brightness, and power to an electrical device with just a handful of off-the
-shef electronic components. This circuitry is superior to using a fixed or
variable resistor for heavy or varying electrical loads, suchas motor and
LED display.
 A microcontroller-based PWM solution uses fewer components and has
the flexibility of varying the duty cycle and frequency on-the-fly through
software. This can be an advantage in a mini sumo battle. Where
searching might be performed at a slower motor speed, but the duty cycle
Needs to be increased to 100% on for pushing an opponent.
 It can be control speed, brightness, and power to an electrical device with
just handful of off the shelf electronics components
Limitation:
 The speed of motor is controlled manually
 It is less reliable
Chapter 9
Data sheet
9.1 Diode (1N4007):
This data sheet provides information on sub miniature size, axial
lead mounted rectifiers for general−purpose low−power applications.
Features
 Shipped in plastic bags, 1000 per bag
 Available Tape and Reeled, 5000 per reel, by adding a “RL” suffix tothe
Part number
 Available in Fan−Fold Packaging, 3000 per box, by adding a “FF”suffix
tothe part number
 Free Packages are Available
Mechanical Characteristics
 Case: Epoxy, Melded
 Weight: 0.4 gram (approximately)
 Finish: All External Surfaces Corrosion Resistant and TerminalLeads are
Readily solder able
 Lead and Mounting Surface Temperature for Soldering Purposes:260C
 Max. for 10 Seconds, 1/16 in. from case
 Polarity: Cathode Indicated by Polarity Band
Maximum Ratings:
Rating
Symbol
1N4007
Unit
†Peak Repetitive Reverse Voltage
Working Peak Reverse Voltage
DC Blocking Voltage
†Non−Repetitive Peak Reverse
Voltage
(halfwave, single phase, 60 Hz)
†RMS Reverse Voltage
†Average
Rectified
Forward
Current(single phase, resistive
load,60 Hz, TA = 75C)
†Non−Repetitive
Peak
Surge
Current(surge applied at rated
load conditions)
Operating and Storage Junction
Temperature Range
VRRM
VRWM
VR
VRSM
1000
V
1200
V
VR(RMS)
IO
700
1.0
V
A
IFSM
30 (for 1 cycle)
A
TJ
Tstg
−65 to +175
C
9.1 Table of Maximum Ratings
9.2 IC (LM324):
The LM124 series consists of four independent, high gain,internally frequency
compensated operational amplifierswhich were designed specifically to operate from
a singlepower supply over a wide range of voltages. Operation fromsplit power
supplies is also possible and the low power supplycurrent drain is independent of the
magnitude of thepower supply voltage.
Application areas include transducer amplifiers, DC gainblocks and all the
conventional op amp circuits which nowcan be more easily implemented in single
power supply systems.For example, the LM124 series can be directly operatedoff of
the standard +5V power supply voltage which isused in digital systems and will
easily provide the requiredinterface electronics without requiring the additional ±15V
power supplies.
Advantages: Eliminates need for dual supplies.
 Four internally compensated op amps in a single package.
 Allows directly sensing near GND and VOUT also goes to GND.
 Compatible with all forms of logic.
 Power drain suitable for battery operation.
Unique Characteristics: In the linear mode the input common-mode voltage range includes
ground and the output voltage can also swing to ground, even though
operated from only a single power supply voltage.
 The unity gain cross frequency is temperature compensated.
 The input bias current is also temperature compensated.
Features: Internally frequency compensated for unity gainLarge DC voltage gain
100 dB.
 Wide bandwidth (unity gain) 1 MHz(temperature compensated)
 Wide power supply range: Single supply 3V to 32V or dual supplies
±1.5V to ±16V.
 Very low supply current drain (700 μA)—essentially independent of
supply voltage.
 Low input biasing current 45 nA (temperature compensated)
 Low input offset voltage 2 mV and offset current: 5 nA
Maximum Rating:
Rating
LM124/LM224/LM324 /
LM124A/LM224A/LM324A
Supply Voltage, V
Differential Input Voltage
Input Voltage
Input Current
(VIN < −0.3V) (Note 6)
Power Dissipation (Note 4)
Melded DIP
Cavity DIP
Small Outline Package
Output Short-Circuit to GND
(One Amplifier) (Note 5)
V+ £ 15V and TA = 25°C
Operating Temperature Range
LM324/LM324A
LM224/LM224A
LM124/LM124A
Storage Temperature Range
Lead Temperature (Soldering, 10 seconds)
Soldering Information
Dual-In-Line Package
Soldering (10 seconds
Small Outline Package
Vapor Phase (60 seconds)
Infrared (15 seconds)
32V
32V
−0.3V to +32V
50 mA
1130 mW
1260 mW
800 mW
Continuous
0°C to +70°C
−25°C to +85°C
−55°C to +125°C
−65°C to +150°C
260°C
260°C
215°C
220°C
9.2 Table of Maximum Rating
9.3 MOSFET(IRF840)
These TMOS Power FETs are designed for high voltage, high speed power
switching applications such as switching regulator, converters, solenoid and
relay drivers.
 Silicon Gate for switching speeds
 Low rDS(on) to minimize on- losses. Specified at Elevated
Temperature
 Rugged – SOA is power dissipation limited
 Source - to – Drain Characterized for Use with inductive loads
Maximum Ratings:
Rating
Symbol
Drain - Source Voltage
Drain-Gate voltage
Gate-Source voltage
Drain currant continuous pulsed
Total [over dissipation @ Tc = 25
c Derate above 25 c
Operating and Storage
Temperature range
VDSS
Vdgr
VGS
ID
IDM
PD
Tj, Tstg
IRF
840
500
500
+ or - 20
8.0
7.0
32
28
125
1.0
-55 to 150
Unit
Vdc
Vdc
Vdc
Adc
Watts
W/ C
C
9.3 Table of Maximum Rating
Maximum ratings are those values beyond which device damage can occur.
Maximum ratings applied to the device are individual stress limit values (not normal
operating conditions) and are not valid simultaneously. If these limits are exceeded,
device functional operation is not implied, damage may occur and reliability may be
affected.
Chapter 10
Daily schedule
Daily schedule:
MONTH
WORK DONE
July
Made our visit to Weldorindustry. Found the problem in
CNC machine drive to motor.
Found the solution in the web sites and other reference
book
Found datasheet and start making circuits.
prepared layout, started mounting and fabricated device
Successfully completed the model and started preparing
report
Completed the report and prepared the presentation
10.1 Daily Schedule
august
August
September
October
November
Reference:
1. Electronic Device & Circuit
2. Principal of Electronics
3. Electronic For You
4. Website www.google.com
www.projectcircuit.com
www.datasheetarchive.com
www.answer.com
www.hobbyprojects.com
J.B.Gupta
V.K.Mehta
Conclusion
Thus by using this project the motor can be controlled and reduced which
stops the loss of power of CNC machine. This project is also cheap and can be
used on large scale. One more is by adding programming IC which controlled
speed of motor automatically.