CHAPTER 11.1 INTRODUCTION

1.1.1 COIN INSERTION MOBILE CHARGER

This is the smart coin based mobile charging system that charges your mobile for particular amount

of time on inserting a coin. The system is to be used by shop owners, public places like railway

stations to provide mobile charging facility. So the system consists of a coin recognition module that

recognizes valid coin is found it signals the microcontroller for further action. if a valid coin is

found it signals the microcontroller and microcontroller then starts the mobile charging mechanism

providing a 5v supply through a power supply through a power supply section to the mobile phone,

now systems also needs to monitor the amount of charging to be provided .So the system can be

used for smart mobile charging at public places.

The objective of this project is inserting the coin using charge for your mobile phone in public

places. This project is very useful to people who are all using mobile phone without charging

condition in public places. In this project, who are all using mobile phones in outside of home are

office without charging condition. The coin based mobile phone charger is very useful to that person

for using coin to charge for that mobile. A sensor system is used to detect the presence of coin. It

may be of different type (IR sensor, Using LDR etc...). The coin is inserted between the transmitted

and received signal.

When a signal came from sensor unit, the microcontroller activates the charger unit for a predefined

time. After that it will reset to normal case. Driver circuit is used for provide the sufficient input

voltage of relay. The relay will on to activate the 230v charger, we will use charger to charge for our

mobile phone.

The major action in this system is controlled by transmitter section; this section consists of IR

transmitter and IR receiver. Here we need to generate IR frequency continuously. So that by using a

small tiny microcontroller frequency is produced and is connected IR receiver continuously receives

the signals from the transmitter. Whenever the light path in between IR transmitter and IR receiver

cuts by an obstacle receiver signal gives low to high pulse. By

to the IR led to generate IR light rays of 38 KHz frequency.

Connecting the receiver output to the micro controller interrupt pin, it gives interrupt to the micro

controller immediately the system gives the buzzer and sends the message to the display on LCD

display to the micro controller.

CHAPTER 2

2.1 System module

Fig:-2.1 Project Module

2.2 8051 Microcontroller

The microcontroller memory is divided into Program Memory and Data Memory. Program Memory

(ROM) is used for permanent saving program being executed, while Data Memory (RAM) is used

for temporarily storing and keeping intermediate results and variables. Depending on the model in

use (still referring to the whole 8051 microcontroller family) at most a few Kb of ROM and 128 or

256 bytes of RAM can be used. However--

All 8051 microcontrollers have 16-bit addressing bus and can address 64 kb memory. It is neither a

mistake nor a big ambition of engineers who were working on basic core development. It is a matter

of very clever memory organization which makes these controllers a real “programmer’s tidbit“.

2.2.1 Pin Diagram:

Fig:-2.2.1 PIN Diagram 8051 Microcontroller

2.2.2 PIN Description:

Pins 1-8: Port 1 Each of these pins can be configured as input or output.

Pin 9: RS Logical one on this pin stops microcontroller’s operating and erases the contents of most

registers. By applying logical zero to this pin, the program starts execution from the beginning. In

other words, a positive voltage pulse on this pin resets the microcontroller.

Pins10-17: Port 3 Similar to port 1, each of these pins can serve as universal input or output.

Besides, all of them have alternative functions:

Pin 10: RXD Serial asynchronous communication input or Serial synchronous communication

output.

Pin 11: TXD Serial asynchronous communication output or Serial synchronous communication

output.

Pin 12: INT0 Interrupt 0 input

Pin 13: INT1 Interrupt 1 input

Pin 14: T0 Counter 0 clock input

Pin 15: T1 Counter 1 clock input

Pin 16: WR Signal for writing to external (additional) RAM

Pin 17: RD Signal for reading from external RAM

Pin 18, 19: X2 X1 Internal oscillator input and output. A quartz crystal which determines operating

frequency is usually connected to these pins. Instead of quartz crystal, the miniature ceramics

resonators can be also used for frequency stabilization. Later versions of the microcontrollers

operate at a frequency of 0 Hz up to over 50 Hz.

Pin 20: GND Ground

Pin 21-28: Port 2 If there is no intention to use external memory then these port pins are configured

as universal inputs/outputs. In case external memory is used then the higher address byte, i.e.

addresses A8-A15 will appear on this port. It is important to know that even memory with capacity

of 64Kb is not used (i.e. note all bits on port are used for memory addressing) the rest of bits are not

available as inputs or outputs.

Pin 29: PSEN If external ROM is used for storing program then it has a logic-0 value every time the

microcontroller reads a byte from memory.

Pin 30: ALE Prior to each reading from external memory, the microcontroller will set the lower

address byte (A0-A7) on P0 and immediately after that activates the output ALE. Upon receiving

signal from the ALE pin, the external register (74HCT373 or 74HCT375 circuit is usually

embedded) memorizes the state of P0 and uses it as an address for memory chip. In the second part

of the microcontroller’s machine cycle, a signal on this pin stops being emitted and P0 is used

for data transmission (Data Bus). In this way, by means of only one additional (and cheap)

integrated circuit, data multiplexing from the port is performed. This port at the same time used for

data and address transmission.

Pin 31: EA By applying logic zero to this pin, P2 and P3 are used for data and address transmission

with no regard to whether there is internal memory or not. That means that even there is a program

written to the microcontroller, it will not be executed, the program written to external ROM will be

used instead. Otherwise, by applying logic one to the EA pin, the microcontroller will use both

memories, first internal and afterwards external (if it exists), up to end of address space.

Pin 32-39: Port 0 Similar to port 2, if external memory is not used, these pins can be used as

universal inputs or outputs. Otherwise, P0 is configured as address output (A0-A7) when the ALE

pin is at high level (1) and as data output (Data Bus), when logic zero (0) is applied to the ALE pin.

Pin 40: VCC Power supply

2.2.3 Architecture of 8051 Microcontroller

Fig :2.2.3 Architecture of 8051 Microcontroller

2.2.4 Block diagram:

Fig:-2.2.4 Block Diagram of 8051 Microcontroller

2.2.5 Micro Controller-AT89S52

The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-

system programmable Flash memory. The device is manufactured using Atmel’s high-density

nonvolatile memory technology and is compatible with the industry- standard 80C51 instruction set

and pin out.

2.2.6 Features

8K Bytes of In-System Programmable (ISP) Flash Memory

Endurance: 1000 Write/Erase Cycles

4.0V to 5.5V Operating Range

256 x 8-bit Internal RAM

32 Programmable I/O Lines

Full Duplex UART Serial Channel

Fully Static Operation: 0 Hz to 33 MHz

2.3 LCD (Liquid Crystal Display)

LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed

images which can be displayed or hidden, such as preset words, digits, and 7-segment displays as in

a digital clock. They use the same basic technology, except that arbitrary images are made up of a

large number of small pixels, while other displays have larger elements.

LCDs are used in a wide range of applications including computer monitors, televisions, instrument

panels, aircraft cockpit displays, and signage. They are common in consumer devices such as video

players, gaming devices, clocks watches, calculators, and telephones, and have replaced cathode ray

tube (CRT) displays in most applications. They are available in a wider range of screen sizes than

CRT and plasma displays, and since they do not use phosphors, they do not suffer image burn-in.

LCDs are, however, susceptible to image persistence.

The LCD screen is more energy efficient and can be disposed of more safely than a CRT. Its low

electrical power consumption enables it to be used in battery-powered electronic equipment. It is an

electronically modulated optical device made up of any number of segments filled with liquid

crystals and arrayed in front of a light source (backlight) or reflector to produce images in color or

monochrome. Liquid crystals were first discovered in 1888. By 2008, annual sales of televisions

with LCD screens exceeded sales of CRT units worldwide, and the CRT became obsolete for most

purposes.

An LCD is made with either a passive matrix or an active matrix display grid. The active matrix

LCD is also known as a thin film transistor (TFT) display. The passive matrix LCD has a grid of

conductors with pixels located at each intersection in the grid. A current is sent across two

conductors on the grid to control the light for any pixel. An active matrix has a transistor located at

each pixel intersection, requiring less current to control the luminance of a pixel. For this reason, the

current in an active matrix display can be switched on and off more frequently, improving the

screen refresh time.

2.3.1 Interfacing of LCD Display

Fig:-2.3.1 Interfacing of LCD Display

2.3.2 PIN Diagram of LCD

Fig:-2.3.2 PIN Diagram of LCD

2.3.3 Diagram of LCD Display

Fig:- 2.2.3 LCD Display

2.3.4 PIN Description of LCD

Fig:-2.3.4 PIN Description of LCD

2.4 Crystal Oscillator

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a

vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency.

This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a

stable clock signal for digital integrated circuits, and to stabilize.

Frequencies far radio transmitters and receivers. The most common type of piezoelectric resonator

used is the quartz crystal, so oscillator circuits incorporating them became known as crystal

oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar

circuits.

Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of

megahertz. More than two billion crystals are manufactured annually. Most are used for consumer

devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also

found inside test and measurement equipment, such as counters, signal generators, and

oscilloscopes.

Besides quartz, the other substances that exhibit the piezo-electric effect are Rochelle salt and

tourmaline. Rochelle salt exhibits the greatest piezoelectric effect, but its applications are limited to

manufacture of microphones, headsets and loudspeakers. It is because the Rochelle salt is

mechanically the weakest and strongly affected by moisture and heat. Tourmaline is most rugged

but shows the least piezo-electric effect. Quartz is a compromise between the piezoelectric effect of

Rochelle salt and the mechanical strength of tourmaline. It is inexpensive and readily available in

nature. It is mainly the quartz crystal that is used in radio-frequency (RF) oscillators.

A crystal oscillator is an electronic oscillator circuit which uses inverse piezoelectric effect, i.e.

when electric field is applied across certain materials it produces mechanical deformation. Thus it

uses mechanical resonance of a vibrating crystal of piezoelectric materiel to create an electric signal

with very precise frequency. They have high stability, quality factor, small size and low cost and

this makes them superior over other resonators like LC circuit, ceramic resonator, turning forks.

2.4.1 Diagram:

Fig:-2.4.0 crystal oscillator

Fig:-2.4.1 Quartz Crystal Oscillators

2.5 Transistor

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical

power. It is composed of semiconductor material with at least three terminals for connection to an

external circuit. A voltage or current applied to one pair of the transistor's terminals changes the

current flowing through another pair of terminal.

Because the controlled (output) power can be higher than the controlling (input) power, a transistor

can amplify a signal. Today, some transistors are packaged individually, but many more are found

embedded in integrated circuits. The transistor is the fundamental building block of modern

electronic devices, and is ubiquitous in modern electronic systems. Following its development in the

early 1950s the transistor revolutionized the field of electronics, and paved the way for smaller and

cheaper radios, calculators, and computers, among other thing.

2.5.1 Diagram:

Fig:-2.5.1 Transistor

Fig:-2.5.1 Transistor configuration

2.6 Diode:

A Diode Is A Two-Terminal Electronic Component With An Asymmetric Transfer Characteristic,

With Low (Ideally Zero) Resistance To Current Flow In One Direction, And High (Ideally Infinite)

Resistance In The Other. A Semiconductor Diode, The Most Common Type Today, Is A Crystalline

Piece Of Semiconductor Material With A P-N Junction Connected To Two Electrical Terminals. A

Vacuum Tube Diode, Now Used Only In Some High-Power Technologies And By Enthusiasts, Is A

Vacuum Tube With Two Electrodes, A Plate (Anode) And Filament (Cathode).

2.6.1 Diagram:

Fig:-2.6.1 Diode 2.7 Resistor:

Resistance R is the amount of opposition to the flow of electrical current. The higher the resistance,

the more difficult it is for current to flow. The lower the resistance, the easier it is for current to

flow. Resistance is measured in units called ohms, named after German scientist and mathematician

Georg Simon Ohm.

2.7.1 Diagram:

Fig:-2.7.1 Resistor

2.7.2 Types of Resistors:

There are many thousands of different Types of Resistors and are produced in a variety of forms

because their particular characteristics and accuracy suit certain areas of application, such as

High Stability, High Voltage, High Current etc., or are used as general purpose resistors where

their characteristics are less of a problem.

All modern fixed value resistors can be classified into four broad groups,

Carbon Composition Resistor - Made of carbon dust or graphite paste, low wattage values.

Film or Cermet Resistor - Made from conductive metal oxide paste, very low wattage values.

Wire-wound Resistor - Metallic bodies for heat sink mounting, very high wattage ratings.

Semiconductor Resistor - High frequency/precision surface mount thin film technology.

Resistance Color Code: In order to identify the nominal resistance and the tolerance of a resistor,

manufacturers typically use a color band system known as the resistor color code. The electronic

color code is used to indicate the values or ratings of electronic components, usually for resistors.

The power rating is not indicated in the resistor color code and must be determined by experience

using the physical size of the resistor as a guide.

For resistors with 5% or 10% tolerance, the color code consists of 4 color bands.

For resistors with 1% or 2% tolerance, the color code consists of 5 bands.

Tight tolerance resistors may have three bands for significant figures rather than two, or an

additional band indicating temperature coefficient, in units of ppm/K.

2.7.3Application:

Resistors are used with transducers to make sensor subsystems. Transducers are electronic

components which convert energy from one form into another, where one of the forms of energy is

electrical. Microphones and switches are input transducers. Output transducers include

loudspeakers, filament lamps and LEDs.

In other circuits, resistors are used to direct current flow to particular parts of the circuit, or may be

used to determine the voltage gain of an amplifier. Resistors are used with capacitors to introduce

time delays.

Most electronic circuits require resistors to make them work properly and it is obviously important

to find out something about the different types of resistor available, and to be able to choose the

correct resistor value, in , , or M , for a particular application.

.

2.7.4Color-coding

Fig:-2.7.4 Color Coding of Resistor

2.8 Relay:

So first what are 9 a relay - a relay is most simply an electronically controlled switch. Switches

come in all types of forms and so do relays. Relays like switches can exist in SPST, SPDT, DPDT,

styles, and so forth. The first part of the word SP tells how many poles there are. SP is single pole,

DP is double pole, and you can have multiple poles. The next part is the throws. Again ST is single

throw, DT is double throw. I like to say that you have a control line in for the pole and the number

of outputs is the throw.

SPST switches are the simplest and the best example is a light switch. SPDT is like a single switch

that controls a fan and a light. DPDT is a switch that can control two lines with a throw of the switch

for instance a motor on a DPDT switch can be reversed clockwise and counter clockwise. An

important note is that you can combine two SPDT switches to form a DPDT switch and similarly do

the same with SPST to form a DPST switch. When costing your robot's parts, sometimes it better to

buy one part in volume and change the design.

2.8.1 Diagram:

Fig:-2.8.1 Spdt Relay

In the above diagram that a relay uses an electromagnet .This is a device consisting of a coil of wire

wrapped around an iron core. When electricity is applied to the coil of wire it becomes magnetic,

hence the term electromagnet. The A B and C terminals are an SPDT switch controlled by the

electromagnet. When electricity is applied to V1 and V2, the electromagnet acts upon the SPDT

switch so that the B and C terminals are connected. When the electricity is disconnected, then the A

and C terminals are connected. It is important to note that the electromagnet is magnetically linked

to the switch but the two are NOT linked electrically.

This application includes the need for voltages/amperages that your microcontroller organically

cannot provide by it. Like motor drivers - a relay circuit (which can be a motor driver in special

cases) can pulse motors on and off but without some complexity, would only control them in one

direction at a time but in some cases when you just need a simple application to go one direction, it

might be a viable solution. Usually you use relays to power high power items from an external

source of power such as a heater, a high amperage motor or fan, a chiller, a floodlight, large LED

arrays, solenoids, or objects you want to either fail open or closed such as heaters or chiller

applications if you run low on power (batteries are drained).

Relays provide the option to have devices either connected as normally open or normally closed.

This means that when power is connected to your circuit by default the gate is either closed or open.

Where the 'normally' indicates whether the relay state is tripped as true. The device will be in its

normally closed state if the power to the relay still persists if a signal is lost to the relay. A good

example of the case of a use of a failure case would be if you ran out of battery power in your

submarine, you'd want one of its last things to do would be to drop ballast of any kind to rise to the

surface.

2.9 One Important Application Is Illustrated In The Diagram Below:

Fig:-2.9.0 Starter Circuit

When the ignition key is turned all the way to the "start" position, it allows electricity to flow to the

starter solenoid (relay) which then connects the battery to the starter motor. So why do we need this

solenoid "middle man"? Couldn't we just eliminate it and connect the ignition wires to the + battery

terminal and the other wire to the starter motor? The important point here is that the electromagnet

is using a small amount of current to control a large amount of current to the starter motor.

(Remember that the electromagnet and the switch are NOT connected electrically). Have you

noticed that all of the wires (except the ignition wires) are purposely drawn with thick lines? The

reason being that some circuits (such as the starter) in a car require a tremendous amount of current.

(If you look at an automobile's battery cables, you will notice they are quite thick.) Connecting the

ignition wires to the battery and then to the starter motor would cause these thin wires to conduct

much more current than they were designed for. These wires would become very hot and the

insulation would start to smoke.

We do have a second choice. We could use thick battery cables for the ignition wires and use a

heavy duty ignition switch. This isn't very practical either. Do you think it would be easy to squeeze

cables into the steering column and to squeeze in a heavy duty ignition switch too? Therefore, the

use of a solenoid is the most practical solution.

2.10 Basic Relay Operation:

2.10.1 The Contacts

Before extending to the various types of relays, I will first explain what and how the basic relay

operates. Each relay has two mechanical parts inside. The first one is the contact(s) of the relay. The

contacts operate similarly to the contacts of a simple switch or pushbutton. You should consider the

contacts as a pair of metals like the following diagram:

Fig:-2.10.1(1) Relay function

The two terminals operate as a switch. When the contacts are in contact then the current flows from

Terminal 1 to Terminal 2. There are two types of contacts: the NO and the NC. NO stands for

Normal Open contact, while NC stands for Normal Closed contact. The Normal Open is a contact

like the one showed in the previous illustration. When the contact is still, then no current flow

through it (because it is an OPEN circuit). On the other hand, a Normal Closed contact allows the

current to flow when the contact is still. Bellow I illustrate both of these contacts.

Fig:-2.10.1(2) Relay normally Open & Closed

You may notice that the NC contact is turned upside-down compared to the NO contact. This is

done in purpose. This way, both contacts (NO and NC) will change state if a force is applied to the

left metal heading from UP to DOWN. The following animation shows how a NO contact operates

by lighting a light bulb.

Fig:-2.10.1(3) Relay OFF Condition

Fig:-2.10.1(4) Relay ON Condition

2.10.2 Interfacing Relays

Fig…. shows how to interface the Relay to microcontroller. There are 2 input channels. Each input

is connected to the triggering coil of the respective relay. There are 2 output channels that each

correspond to an input. When the input is energized, the relay turns on and the '+' output is

connected

5v to + 24v. When the relay is off, the '+' output is connected to Ground. The output is permanently

2.10.3 Diagram:

wired to Ground.

Fig:-2.10.3 Interfacing Relays

CHAPTER 3

4.1 Introduction

The objective of this project is inserting the coin using charge for your mobile phone in public

places. This project is very useful to people who are all using mobile phone without charging

condition in public places. In this project, who are all using mobile phones in outside of home are

office without charging condition. The coin based mobile phone charger is very useful to that

person for using coin to charge for that mobile. A sensor system is used to detect the presence of

coin. It may be of different type (IR sensor, Using LDR etc...). The coin is inserted between the

transmitted and received signal.

When a signal came from sensor unit, the microcontroller activates the charger unit for a predefined

time. After that it will reset to normal case. Driver circuit is used for provide the sufficient input

voltage of relay. The relay will on to activate the 230v charger, we will use charger to charge for

our mobile phone.

The major action in this system is controlled by transmitter section; this section consists of IR

transmitter and IR receiver. Here we need to generate IR frequency continuously. So that by using a

small tiny microcontroller frequency is produced and is connected to the IR led to generate IR light

rays of 38 KHz frequency.

3.1.1 Block Diagram:

Fig:-3.1.1 Block Diagram of Prepaid Charger

3.1.2 Circuit Diagram:

Fig :-3.1.2 Circuit Diagram of Prepaid Charger

3.2 IR Sensor

Infrared sensors (IR) is invisible radiant energy electromagnetic radiation with longer wavelengths

than those of visible light extending from the normal red edge of the thermal radiation emitted by

objects near from temperature is infrared. Infrared radiation was discovered in 1800 by astronomer

sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy

then red light by, means of its effect upon a thermometer.

3.3 Working Principle:

In our vibration alarm system, we will be having 

• Infra-Red sensor,

• Amplifiers,

• Comparator and

• Relay

The Infra-Red sensor is used in this circuit. If there is any interrupt between the IR LEDs, the sensor

senses and sends the corresponding electrical output signal to amplifier circuit. 

The amplifier circuit results in further amplification of signals. The amplified signal is given to

comparator. The comparator compares the incoming signal with reference. If the incoming signal is

more, it operates the relay.

3.3.1 Diagram:

Fig:-3.3.1 Working of Coin Based Mobile Charger

CHAPTER 4

4.1 PCB Wizard

PCB Wizard is a strong application that can be used for designing circuit boards whether they are

single sided or double sided printed. PCB Wizard is loaded with all the necessary tools that are

needed at each step of PCB circuit designing. A large library of components has also been provided

for the ease of use in PCB designing. These components can be easily inserted into your project

and there is no need to draw them from scratch.

4.2 PCB Manufacturing Process

The PCB manufacturing process is very important for anyone involved in the electronics industry.

Printed circuit boards, PCBs, are very widely used as the basis for electronic circuits. Printed circuit

boards are used to provide the mechanical basis on which the circuit can be built. Accordingly

virtually all circuits use printed circuit boards and they are designed and used in quantities of

millions.

4.3PCB Layout

Lay out of the desired circuit is the most important in any circuit board manufacturing process. The

following points are to be observed while performing the layout of the PCB.

Sufficient space should be maintained between two components. High heat dissipation components

like high voltage resistors should be mounted at a sufficient distance from the semiconductors and

electrolytic capacitors. Components layout should make proper combination with copper side circuit

layout. Circuit copper line thickness should be decided taking into account the current drain in the

circuit.

4.3.1 PCB Lay Out Of Prepaid Charger

Fig:-4.3.1 PCB Lay Out Of Prepaid Charger

4.4 Preparation of Screen

Nylon bolting cloth (Silk screen cloth) is stretched and attached to a wooden frame. Photosensitive

chemical (silcot-6) and ammonium bicarbonate is spread on cloth and dried in total darkness. The

screen is exposed to UV light and is developed in water.

4.4.1 Printing Process

The screen is placed on suitable copper laminated sheet on copper side and circuit black printing ink

(acid resistant paint) is spread on it. After printing the PCB should be allowed to dry for at least 10

hrs. In a dust proof chamber.

4.4.2 Etching Process

Etching process requires the use of chemicals acid resistant dishes and running water supply Ferric

chloride is maximum used solution but other enchants such as ammonium per sulfate can be used.

Nitric acid can be used but in general it is not used due to poisonous fumes. The pattern prepared is

glued to the copper surface of the board using a latex type of adhesive that can be cubed after use.

The pattern is laid firmly on the copper use a very sharp knife to cut round the pattern carefully a

remove the paper corresponding to the required copper pattern areas. Then apply the resist solutions,

which can be kind of ink proportion fort the purpose maintaining smoothing clean outlines as far as

possible. While the board is drying test all the components.

Before going to next stage, check the whole gotten and cross cheek against the circuit diagram

check for any freeing matte on the copper. The etching bath should be in a galls or enamels disc. If

using crystal of ferric-chloride these should be thoroughly dissolved in water to the proportional

suggested. There should be 0.5 Lt. of water for 125 Gm. of crystal.

Water liquid should be thoroughly deflated and druid in water land; never pour down the drain. To

prevent particles of copper hindering further etching, agitate the solutions carefully be gently

twisting or rocking the tray.

The board should not be left in the bath a moment longer than is needed to remove just the right

amount of copper. In spite of there being a resist coating there is no protection against etching away

through exposed copper edges; this leads to over etching. Have running water ready so that etched

board can be removed properly and rinsed; this will hall etching immediately.

Fig:-4.4.2 The PCB Etching Process with Ferric Chloride (FeCl3) Solution

4.4.3 Drilling Process

Drilling is one of those operations that call for great care because most of the holes will be made a

very small drill. For most purposes a 1 mm drill is used Drill all holes with this size first those that

need to be larger can be easily drilled again with the appropriate lager size.

Fig:- 4.4.3 Drilling of PCB

4.4.4 Green Making

It is done with special epoxy paint and special thinner is requited for cleaning the screen. It provides

as better and also prevents frequency overlapping between the tacks at high frequency operation.

4.4.5 Thinning

It is an electroplating process (tin plating) done to increases the conductivity of the conducting

medium and to avoid oxidizing effect.

4.4.6 Component Mounting

All components are mounted at their respective position as per the components layout. Proper

precautions should be taken during mounting process.

Fig:-4.4.6 Components mounted on PCB

4.4.7 Component Assembles

From the greatest variety of electronic components available today, which runs into tens of

thousands of different types it is often a perplexing task to know which the right task for a given job

is. There should be damage such as hair line crack intuit opera on PCB that could age a serious

office on the operational ability to the completed assemble. If there are than they can and should be

repaired fiesta bye soldering a short link of bare copper wire over the affected part.

The most popular method of holding all the items is to been the wires future apart after they even

been indebted in the appropriate holes. This will hold the component in position ready for soldering.

Some components will be considerably larger than other occupying and possible partially obscuring

neighboring components. Because of this best to start by mounting the smallest first and progressing

through to the largest. Before starting make certain that no further drilling I likely to be necessary

because access may be impossible later.

Next will probably be the resistor small signal diodes of other similar size components some

capacitor are very small but it would be best to fit these after words when fitting each group of

components marks of each one on the components it’s as it is fitted and if we have to leave the job

we know where to recommence. Although transistor & integrated circuit are small items there are

good reasons for leaving the soldering of these until the last step the main pint is that these

components are sensitive to heart and is subjected to prolonged application to the soldering iron they

could be internally damaged.

All the components before mounting are rubbed with sandpaper so that oxide layer is removed

from their tips. Now they are mounted according to the components layout.

4.5 Soldering Techniques

A soldered connection ensures metal continuity. The soldering process involves: Melting of the flux

which in turn removes the oxide films on the metal to be soldered. Melting the solder which remove

the impurities. The solder partially dissolve of the metal in the connection. The solder cools and

fuses with the metal.

The soldering techniques involve knowledge of:-

Soldering iron.

Soldering wire.

Soldering procedure.

Replacing components.

Prosecutions of when using C-MOS, devices.

Knowledge of good and bad soldering joints.

4.5.1 Soldering Iron

Soldering iron is an essential tool for soldering. A. Soldering iron should give sufficient heat a melt

solder by heat transfer when the iron tip is applied to a connection to be soldered. The selection of

the soldering iron can be made as regard to its tips size shape and wattage. Soldering iron

temperature is selected and controlled according to the work to be performed. Generally two types

of soldering irons are available: Soldering Pencil and Soldering Gun.

4.5.2 Soldering Pencils

These are light weight soldering iron which can generate around 12 watts to 50 watts of heat. Too

much heat applied during soldering can damage components and peel off tracks on the circuit board

soldering. Too much heat applied during soldering can damage components and peel off tracks on

the circuit board.

4.5.3 Soldering Materials

The soldering material is used to join together two or more metals at temperatures below their

melting point. The solder alloy consists of Lead (37%) and Tin (63%). The continuous connection

between two metals joint is made by solder materials.

Most commonly used solder wire consists of 60% of Tin 40% Lead. This is in the form of a hollow

wire whose center is filled with an organic paste like material called rosin. Its melting temperature is

190 degree centigrade.

Flux is a material used to aid soldering process. Flux is needed to scratch away the small film of

oxide on the surface of metals to be soldered. This flux forms a protective film that prevents re-

oxidation while the connection is heated to the point at which the solder melts. Flux is very helpful

on old dusty, eroded joint.

4.6 Soldering Procedure

The soldering procedure involves selection of soldering iron cleaning of components to be soldered

and cleaning of the PCB to be soldered. The soldering iron should be selected according to the job

and should be powerful enough to provide heat. The tip of the soldering iron should be selected as

per the space available for soldering. The component that has to be soldered should be properly bent

and its leads should properly insert in the PCB before. If one has already identified the fault

component, then one should not try to remove or DE solder the component. The components should

simply be cut and taken out.

Soldering is a joining process wherein coalescence is produced by heating below 800°F,

using a non-ferrous filler metal with a melting point below that of the base metal. The

metals to be joined dictate the flux, solder, and heating methods to be used. Base metals

are selected for specific properties such as electrical conductivity, weight, and corrosion

resistance.

To achieve a sound soldered joint, the following should be considered:

Joint design: They should be designed with the requirements of soldiers and their

limitations in mind.

Pre-cleaning: The surfaces must be thoroughly cleaned to allow the solder to wet

the base metal.

Fluxing: A flux must be provided to remove traces of surface film or oxides and to

prevent formation of oxides during the soldering operation.

Proper fixtures or alignment of parts must be maintained to insure a sound soldered

joint.

Heating of the base metals should be uniform or even on base metals, to insure

good penetration of the filler alloy into the joint. If a noncorrosive flux is used no

further cleaning is necessary. The use of a corrosive flux makes flux residue

removal imperative.

CHAPTER 5

Software Used:-

5.1 Introduction

5.1.1 SCH Simulation Software Version 7.0.2

This software is a easy-to-use schematic design program. Express SCH schematic design software is

just as easy-to-use as our PCB layout software, both having the same user interface. After spending

a few minutes to teach one, mastering the other takes no time at all Step 1: Select the Components

Begin your schematic by placing the components. Select the parts from the Component Manager

Dialog box. Express SCH includes a large library with hundreds of component symbols (ICs,

resistors, capacitors...) that you can use to draw your electronic circuits Step 2: Position the

Components

Drag each component to the desired location on the page. The Snap to grid feature makes it easy to

neatly align the symbols. If all of the components do not fit on a single page, add additional sheets.

All the sheets of a schematic are linked together and saved in one file Step 3: Add the Wires

now draw the wires to connect the parts together. Add each wire by clicking on a component's pin,

then dragging the wire to the pin it connects to Step 4: Edit the Schematic

making changes to a schematic is simple using standard commands such as Copy, Cut and Paste.

Rearranging the components is easy by dragging them with the mouse. Wires always stay connected

to their pins, even when you move things around Step 5: Link the Schematic and PCB

after you complete your schematic, it can be linked to your circuit board layout file. This image of

the Express PCB layout software shows how it guides you in designing your board by highlighting

in blue the pins that should be wired together.

5.2 Proteus PCB Design and Simulation Software

5.2.1 ISIS Proteus Version 2.6

Proteus is a simulation and design software tool developed by Lab center Electronics for Electrical

and Electronic circuit design. It also possess 2D CAD drawing feature. It deserves to bear the tagline

“From concept to completion”.

It is a software suite containing schematic, simulation as well as PCB designing.

ISIS is the software used to draw schematics and simulate the circuits in real time. The simulation

allows human access during run time, thus providing real time simulation.

ARES is used for PCB designing. It has the feature of viewing output in 3D view of the designed

PCB along with components.

The designer can also develop 2D drawings for the product.

5.2.2 Features

ISIS has wide range of components in its library. It has sources, signal generators, measurement  

and analysis tools like oscilloscope, voltmeter, ammeter etc.., probes for real time monitoring of the

parameters of the circuit, switches, displays, loads like motors and lamps, discrete components like

resistors, capacitors, inductors, transformers, digital and analog Integrated circuits, semi-conductor

switches, relays, microcontrollers, processors, sensors etc.

ARES offers PCB designing up to 14 inner layers, with surface mount and through hole packages. It

is embedded with the foot prints of different category of components like ICs, transistors, headers,

connectors and other discrete components. It offers Auto routing and manual routing options to the

PCB Designer. The schematic drawn in the ISIS can be directly transferred ARES.

CHAPTER 6-

The program used in our project

Code:

$MOD51 rs

equ p3.1 e

equ p3.0 dl

equ p1 ORG

00H Ljmp

main ORG

0003H ISR:

mov dl,#01h

acall command

mov dl,#80h

acall command

mov dl,#'C'

acall data1 mov

dl,#'H' acall

data1 mov

dl,#'A' acall

data1 mov

dl,#'R'

acall data1

mov dl,#'G'

acall data1

mov dl,#'E'

acall data1

mov dl,#' '

acall data1

mov dl,#'Y'

acall data1

mov dl,#'O'

acall data1

mov dl,#'U'

acall data1

mov dl,#'R'

acall data1

mov dl,#' '

acall data1

mov dl,#'C'

acall data1

mov dl,#'E'

acall data1

mov dl,#'L'

acall data1

mov dl,#'L'

acall data1

SETB P3.7

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY

ACALL DELAY1

ACALL DELAY1

ACALL DELAY1

ACALL DELAY1

ACALL DELAY1

ACALL DELAY1

mov dl,#01h

acall command

mov dl,#80h

acall command

mov dl,#'3'

acall data1 mov

dl,#'0' acall

data1 mov dl,#'

' acall data1

mov dl,#'S'

acall data1 mov

dl,#'E' acall

data1 mov

dl,#'C' acall

data1 mov dl,#'

H' acall data1

mov dl,#'R'

acall data1 mov

dl,#'E' acall

data1

mov dl,#'M'

acall data1

mov dl,#'A'

acall data1

mov dl,#'I'

acall data1

mov dl,#'N'

acall data1

mov dl,#'I'

acall data1

mov dl,#'N'

acall data1

mov dl,#'G'

acall data1

ACALL DELAY

ACALL DELAY

ACALL DELAY

CLR P3.7

RETI

mov dl,#0eh

acall command

mov dl,#06h

acall command

mov dl,#01h

acall command

mov dl,#80h

acall command

mov dl,#'I'

acall data1 mov

dl,#'N' acall

data1 mov

dl,#'S' acall

data1 mov

dl,#'E' acall

data1 mov

dl,#'R' acall

data1 mov

dl,#'T' acall

data1 mov

dl,#'I ' acall

data1 mov

dl,#'C' acall

data1

mov dl,#'O'

acall data1

mov dl,#'I'

acall data1

mov dl,#'N'

acall data1

SJMP MAIN

command:clr rs

setb e

acall delay

clr e

ret

data1: setb rs

setb e

acall delay

clr e

ret

Delay: mov

r2,#100

back1: mov

r1,#50 back2:

mov r0,#10 b

djnz r1,back2

djnz r2,back1

ret

Delay1: mov r3,#200

back11: mov r4,#250

back22: mov r5,#200

back33: djnz r5,back33

djnz r4,back22

djnz

r3,back11 ret

end

CHAPTER 77.1 Applications:

1. Useful to public for using coin to charge for the mobile phone in any palace.

2. It can be used for different type of mobiles.

3. It is used for emergency charging purposes.

4. It can be installed railway stations, bus stops, villages and rural areas and public places.

5. It can be installed in office and colleges for pay charging facility.

7.2 Advantages:

1. Simple and hand efficient.

2. Less expensive.

3. Reduced man power.

4. Low power consumption.

5. Installation is easy.

6. It can be useful while travelling and when we don’t have charger with us during travel.

7. Simple to operate.

7.3 Conclusion:

The coin based mobile phone charger is very useful to public for using coin to charge for the mobile

phone in any public places just like charging it normally owing to the fact that it relayed the

electricity through the coin based mobile charger needed to bring the mobile phone back to life.

A novel method of charging mobile batteries of different manufactures using solar power has been

designed and developed for rural and remote areas where the grid power is not available at any

time at any palace.

7.4 Future Enhancement:

The project can be used in the following areas:-1. Railway station:-This type of project is used in railway station for public palace.

2. Shop:-coin based project charger is install any shop and earn money.

3. Rural areas:-This project is installing in rural areas where the power grid is not available

at any time.

4. Public Place:-This project is very useful to people who are using mobile phone without charging condition in public places.

REFERENCE:

BOOKS:

1) Electronic devices and circuit theory.

2) Electronic projects.

3) Microelectronic circuits.

4) Electronic for you.

WEBSITES:

1) www.efyindia.com

2) www.nationalsemiconductor.com

3) www.electroprojectindia.com

4) www.alldatasheet.com

5) www.howstuffworks.com