| Content | CHAPTER ONE
1.0 INTRODUCTION
The most recent advancement in technology has really given birth to different development in the field of engineering. Provision has been made by technologist who covers a wide range of humans environment, given solution to humans problems.
In the recent times, power supply has been epileptic in the country which has really affected consistent power source. Many power systems were found to be able to maintain power supply to the load during mains failure PHCN. Most of these loads were designed so that electrical supply to them should be maintained without interruption. Electricity can be generated by devices to convert some readily available sources of energy since electricity generation can be interrupted at any time as a result of fault and all electronic devices need an alternating current , the use of an inverter to utilize an alternative source of energy becomes so necessary.
An inverter is an electronic device which converts DC energy to AC energy. Thus, the technological breakthrough resulting to the production of this system has encouraged the optimum utilization of computers and related equipments. The beauty of inverter system is the fact that it accepts all the power anomalies, conditions and filters properly the public power supply output to most load which require pure grade sinusoidal voltage rated output. They are used in a wide variety of applications such as the complicated electronic systems of orbiting satellite and cool astronaut suites. Inverters are also used to operate gyroscope and other air borne instruments. Due to low voltage power sources such as solar cells, nuclear cells, and fuel cells, inverters has become increased in demand.
The system is unaffected by variation in the mains supply and during the period of power failure will continue to supply to the load for a specified duration. Modern DC to AC inverters is reliable and requires less maintenance
1.1 AIMS AND OBJECTIVES
The purpose of this project is aimed at designing and constructing a DC/AC inverter. It is necessitated by the quest to supply voltage to electrical electronic appliances in the advent of power failure from the mains PHCN.
1.2 JUSTIFICATON
In this design, the DC/AC inverter should be able to switch over to an alternating current AC at the advent of been powered by the mains and automatically charging the battery and reverse is the case when there is power failure from the mains.
1.3 LIMITATION
The DC/AC inverter can be produced or designed in different wattage as well as the output voltage models depending on the wattage and output voltage required by the users. It can be mounted or used in different areas of interest e.g. computer systems, ATM, household electronics either 120v or 240v output or many more.
1.4 METHOLOGY
A modular approach was adopted in which the design was incorporated namely, DC/AC converter unit. The a stable multi-vibrator low/high voltage transformation unit, charging unit, output unit.
These subunits would be designed, constructed and tested separately when all are confirmed to be working properly, there shall be appropriately connected. As much as practicable integrated circuit IC chips will be used to reduce components carried and enhance compatibility and reliability of the systems.
TABLE OF CONTENT
TITLE PAGE
CERTIFICATION i
DEDICATIONii
ACKNOWLEDGEMENTiii
ABSTRACTiv
TABLE OF CONTENTvixi
CHAPTER ONE
INTRODUCTION1
1.1 AIMS AND OBJECTIVES2
1.2 JUSTIFICATION2
1.3 LIMITATION23
1.4 METHODOLOGY3
1.5 SCOPE OF THE PROJECT3
1.6 BLOCK DIAGRAM4
1.7 DEFINITION OF OPERATIONAL TERMS45
CHAPTER TWO
2.0 LITERATURE REVIEW THEORY OF COMPONENTS6
2.1 DIODES67
2.1.1 TYPES OF SEMI CONDUCTOR DIODES7
2.1.2 NUMBERING AND CODING SCHEMES8
2.1.3 CONSTRUCTION OF A PN JUNCTION DIODE9
2.1.4 WORKING PRINCIPLE10
2.1.5 VOLTAGE CURRENT CHARACTERISTICS1011
2.1.6 DIODE PARAMETERS1112
2.1.7 APPLICATIONS OF DIODE12
2.2 RESISTORS13
2.2.1 TYPES OF RESISTORS13
2.2.2 COLOR CODING IN RESISTORS1417
2.2.3 LINEAR AND LOGARITHMIC TRAC1718
2.2.4 OHMS LAW1819
2.3 SWITCHES RELAY 1920
2.3.1 TYPES OF SWITCHES20
2.3.2 RELAYS2024
2.4 CAPACITORS25
2.4.1 DIELECTRICS25
2.4.2 CAPACITANCE25
2.4.3 TYPES OF CAPACITORS2628
2.4.4 INDICATING CAPACITANCE2830
2.5 TRANSFORMERS30
2.5.1 MUTUAL INDUCTANCE31
2.5.2 TRANSFORMER CONSTRUCTION32
2.5.3 TYPES OF TRANSFORMERS3133
2.5.4 E.M.F. EQUATION OF A TRANSFORMER3335
2.6 TRANSISTORS36
2.6.1 TRANSISTOR BIASING3638
2.6.2 TRANSISTOR AS A SWITCH3739
2.6.3 TRANSISTOR AS AN AMPLIFIER40
2.7 MULTIVIBRATORS40
2.7.1 ASTABLE MULTIVIBRATOR4143
2.7.2 CIRCUIT OPERATION4344
2.7.3 SWITCHING TIMES4445
2.8 POWER CELLS46
2.8.1 PRIMARY CELLS47
2.8.2 SECONDARY CELLS AND BATTERIES48
2.9 CONDUCTORS48
CHAPTER THREE
3.0 CONSTRUCTION OF DCAC INVERTER49
3.1 POWER CELL UNIT BATTERY49
3.2 DCAC CONVERTER UNIT4950
3.3 LOWHIGH VOLTAGE TRANSFORMATION UNIT5153
3.3.1 DETERMINATION OF THE WIRE DIAMETER53
3.4 THE BATTERY CHARGING UNIT54
3.4.1 FLOAT VOLTAGE55
3.4.2 EQUALISE VOLTAGE5556
3.4.3 TYPES OF CHARGE56
3.4.4 TRICKLE CHARGE5657
3.4.5 TYPICAL BATTERY CHARGER DESIGN57
3.5 PRINCIPLES OF OPERATION5760
CHAPTER FOUR
4.0 CONSTRUCTION TESTING AND RESULT61
4.1 CONSTRUCTION61
4.1.1 BREAD BOARD61
4.1.2 VERO BOARDING62
4.2 CONSTRUCTION OF CASING6263
4.3 TESTING6465
4.4 RESULT65
4.5 BILLS OF ENGINEERING MEASUREMENT AND
EVALUATION66
CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION67
5.1 CONCLUSION67
5.2 RECOMMENDATION67
5.3 REFERENCES6869
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CHAPTER ONE
INTRODUCTION
The Mitchell tilting pad apparatus is a hydrodynamic measuring instrument developed in the early 1880s in the laboratory of Beauchamp Tower in England. Tower was employed to study the friction in railway journal bearings and come up with the best method of lubricating them. The Mitchell tilting pad apparatus is used broadly in two different experiments namely;
1 Determination of the load carrying capacity of the slider bearing.
2 Confirming the theory of the hydrodynamic lubrication.
Tilting pad journal bearings are a source of both static support and dynamic stiffness and damping. Tilting pad journal bearings have a number of pads, typically four or five. Each pad in the bearing is free to rotate about a pivot and cannot support a moment. As a result, the destabilizing forces are greatly reduced or eliminated, and the bearings are no longer a potential source of rotor dynamic instability. This feature has made tilting pad journal bearings the standard fluid film bearing for most high speed applications. High speed rotor dynamic applications often have rotors that pass through one or two bending critical speeds as the machines are accelerated to the operating speed. The damping from the fluid film bearings is required to safely pass through these bending critical speeds as the rotating element is accelerated. The damping also helps suppress potentially destabilizing forces from sources such as radial seals, balance pistons, impeller eye seals, internal friction fits, and unbalanced electromagnetic forces.
1.1 AIMS AND OBJECTIVES OF THE PROJECT
The project designing, constructing and testing on the Mitchell tilting pad apparatus is aimed at achieving the following objectives:
1 To verify the hydrodynamic theory of lubrication as it was propounded by Beauchamp Tower in 1880 AD.
2 To determine the load carrying capacity of the tilting pad slider bearing
3 To provide the fluid mechanics laboratory of the Mechanical Engineering Department with a hydrodynamic fluid analyzing apparatus.
4 To activate and motivate the students potentials into practically solving problems facing mankind.
5 To run tests with the apparatus and compare the results obtained with the established or ideal standards.
1.2 PROJECT JUSTIFICATION
Engineering is known to be to be practice oriented discipline. In other words, no useful Engineering endeavor can exist in theory only, it must be applied to touch and transform life through meaningful practice. Therefore, this project task given to us is to ensure the knowledge we students gained throughout our five year degree programme and channeled towards the construction of Mechanical Engineering equipment's.
1.3 APPLICATIONS AND USES
The Mitchell tilting pad apparatus is applicable in experiments which does not require;
1 Hydrostatic lubrication
2 Boundary lubrication
3 Solid lubrication
4 Elastohydrodynamic form of lubrication.
It only finds its application useful in full film or fluid lubrications in motion, in which there is a situation that the load carrying surfaces of the bearing are separated by an adequate supply at all times of a relatively thick film of lubricant, so as to prevent metal to metal contact and that the stability thus obtained can be explained by the laws of fluid mechanics. The Mitchell tilting pad is a Mechanical Engineering apparatus with the above aims and objectives.
1.4 LIMITATIONS
The Mitchell tilting pad apparatus is limited to use with the specified oil viscosity SAE20W/50 or Whitz oil which is typical automobile engine oil. The Mitchell tilting pad apparatus is also limited to operation when there is power failure or insufficient supply of power that drives the electric motor, other limitations are stipulated below;
1 The use of lubricants that do not obey Newtons law of viscous flow.
2 The use of compressible lubricants
3 Fluid pressure varying in the axial direction.
From the limitations stated above, it is necessary to identify the Newtons viscous effect, which states that the shear stress in the fluid is proportional to the rate of change of velocity with respect
| CHAPTER ONE
INTRODUCTION
1.1 Background of the study
A battery charger is a device used to introduce energy into a secondary cell or rechargeable battery by forcing an electric current through it. The charging protocol depends on the size and type of the battery being charged. Some battery have high tolerance for recharged by connection to a constant voltage source or a constant current source; simple chargers of this type require manual disconnection at the end of the charge cycle, or may have a timer to cut off charging current at a fixed time. Other battery types cannot withstand long highrate overcharging, the charger may have temperature or voltage sensing circuits and a microprocessor controller to adjust the charging current, and cut off at the end of charge.
A tackle charger provides a relatively small amount of current, only enough to counteract selfdischarge of a battery that is idle for a long time. Slow battery chargers may take several hours to complete a charge, highrate chargers may restore most capacity within minutes or less than an hour, but generally require monitoring of the battery to protect it from overcharge Emerson, 1998.
A battery, which is actually an electric cell, is a device that produces electricity from a chemical reaction. In one cell battery, a negative electrode; an electrolyte, which conducts ions; a separator, also an ion conductor; and a positive electrode. an electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technical improved Daniell Cell in 1936, batteries have become a common power source for many household and industrial applications Emerson 1998.
There are two types of batteries: Primary Batteries disposable batteries, which are designed to be used once and discarded, and Secondary Batteries rechargeable batteries, which are designed to be recharged and used multiple times. Battery comes in many size, from miniature cells used to power hearing aids and wristwatches to battery banks the size of rooms that provide standby power for telephone exchanges and computer data centers and inverters.
However, in recent times, battery charger has become very useful and popular to DC equipment. Most of the electronic devices such as laptops, mobile phone, etc., and mobile machines like vehicle and motorcycles operational capacity depend on the DC power supply from a battery.
1.2 Scope of the study
This project work is limited to the construction and demonstration of a simple battery charger of 12volts. The circuit input voltage is 240volts from the A.C supply mains which will be stepped down by a stepdown transformer to 12volts. The 12volts A.C is rectified through a bridge rectifier and filtered through capacitor connected in parallel from the positive terminal of the bridge rectifier. The output voltage is used to charge a battery.
1.3 Statement of the problem
A simple 12volts charger works by supplying a constant DC or pulsed DC power source to a battery being charged. The simple charger does not alter its output based on time or the charge on the battery. This simplicity means that a simple charger is inexpensive. The circuit of a battery charger has the ability to convert voltages from one form to another usually AC to DC voltages. This process is carried out through the use of some important components like: rectifiers, capacitor to filter and remove ripples from the AC source and a voltage regulator IC. However, this project is based on the construction of a 12volts simple battery charger with local materials to reduce cost.
1.4 Purpose of the study
The purpose of this project work is to design construct and demonstrate how a simple 12volts battery charger works.
1.5 Significance of the study
A simple 12 volt battery charger is a simple circuit that comprises of different component that are soldered together on a circuit board to give or produce a require function. Therefore, the importance of this project work is to aid both technicians and students on how to construct a simple battery charger circuit and how it works.it is hoped that after the construction of this charger circuit, it will be kept on the laboratory to be used for battery charging and for practical's and other academic functions.
1.6 Limitation
During the project work, the researcher encountered the following problems which in one way or the other have prevented him from completing the work at the usually time. These include: financial problems, time factor and unavailability of material which the researcher have to move from far distance area in search of textbooks and other important materials. |
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND
Heart beat rate means the number of heartbeats per unit time, usually expressed as beats per minute bpm. The human heart pounds to pump oxygen rich blood to the muscles and carry cell waste products away from the tissues. Heartbeat rate can vary according to the demand of the muscles to absorb oxygen and excrete carbon dioxide changes such as during exercise or sleep. It also varies significantly between individuals based on age, fitness and genetics. This means that the heart must beat faster to deliver more oxygen rich blood. During exercise routines, the heartbeat rate gives a strong indication of how effective the exercise is to the body.
The patient monitoring systems is one of the major improvements in the global health care program because of its advanced technology. A patient monitoring system measures the heartbeat and body temperature by using embedded technology. This advancement in technology is highly needed because many sick patients at the hospitals die because of high fever and heart attacks. The trend of cardiovascular disease has shown that heart beat rate plays a key role in determining the possibility of a heart attack while an increase in the body temperature can induce fever on a patient.
Another vital thing to monitor in a patient is the heartbeat rate. It is very important that the heartbeat is to be normal. That is 72 BPM. If there is any abnormality, then the patient is in distress. Heartbeat rate means the number of heartbeats per unit of time. The normal heartbeat rate of a resting person is about 70 bpm for adult males and 75 bpm for adult females. The average heartbeat per minute for 25year old ranges between 140170 beats per minute while for a 60year old it is typically between 115140 beats per minute and body temperature is 37 degree Celsius or 98.6 Fahrenheit. . Normally it is difficult to keep track of the abnormalities in the heartbeat count of by manual means. Patients are not well versed with the manual treatments, which the doctors normally use for tracking the count of the heartbeat. Thus, there must be some kind of device which would help patients and their family member to keep track of their health by themselves. This sole reason is why this project presents a heartbeat and temperature monitoring device using radio frequency RF.. The concept of developing an RF. based patient monitoring device is to have a simple home and hospital based pulse and body temperature monitoring device for sick persons that are in critical condition and needs to be constantly or periodically monitored by clinician or family.
1.2 WHAT IS A PATIENT HEARTBEAT AND TEMPERATURE MONITOR USING RF.
A patient heartbeat and temperature monitor using RF. is a radio frequency based pulse wave and body temperature monitoring system, which allows the control of a sick persons condition in real time. The system monitors the heart beat and temperature of a patient simultaneously and if the patients heartbeat rate or body temperature is abnormal, the system alerts sends an alert to the doctor or patients family members to quickly examine or diagnose the patients condition and take early precaution to save the patients life. The alerts sound can be triggered at any time as long as there is a deviation in the health condition of the patient from the normal, such that the status of the patient can be known on time. The system consists of a sensor, which monitors the patient and sends a signal to a microcontroller, which processes it to determine the temperature and heartbeat rate of the patient before sending an alert to a receiver using radio frequency. The receiver has to be in the possession of the patients doctor or family members. This project can also be used by athletes who engage in physical exercise and by medical professionals. Individuals, such as athletes, cyclists or those who are interested in monitoring their heartbeat rate and body temperature to gain maximum efficiency from their training can also use this project. It can be used during physical exercise and healthcare.
1.3 PROBLEM DEFINITION
The human health is one of the most important concerns in the world today. Anything/everything becomes meaningless when one becomes sick and dies due to improper Medicare. For health reasons, people, governments and several voluntary bodies spend a lot of money to ensure a better health condition for themselves and the entire populace. Scientists and Engineers are always at work to device a means of supporting/sustaining a sound health condition for all through the invention of numerous technologies both Electrical/Mechanical gadgets that are in use for health care delivery today. The heart is a very delicate organ in the human body once it stops beating, nothing else matters. Thus, If early actions are taken and on time the heart condition can be managed effectively and many patients can be cured and saved.
1.4 AIMS AND OBJECTIVES
The major aim and objective of this design of a patient heartbeat and temperature monitor using RF. is to help the doctors and family members to keep track of the heartbeat condition of their loved ones as well as their body temperature in the case of an abnormality in the health condition for those with heartbeat defects and those that run excessive high temperature beyond normal. If any varied change takes place, it is notified. This notification through RF. Channel would to take an appropriate action at an instance of time, thereby alerting the appropriate persons.
1.5 SIGNIFICANCE OF THE PROJECT
There are various instruments available in the hospitals to keep track of the internal body changes, but many of them have limitations regarding to maintenance, cost, size of instruments, and mobility. This project is so significant because it is mobile, small in size, cost effective, very easy to use, highly efficient performance, portable and light in weight etc. It uses RF. to help both the patient and the concerned doctor to take an appropriate action.
1.6 SCOPE OF THE PROJECT
This project operates at a 30 feets distance on open space. It is designed to operate with an alkaline battery of a minimum of 9 volts to a maximum of 12v consumes 50mA. It uses a buffer, temperature sensor, AT89c51 Microcontroller and a led display with buzzer for the alert. The hardware and soft ware of the system is oriented towards the AT89c51 single chip microcontroller. Hence, reducing the size of the device. A regulated 3.7v RF. operates in the frequency range of 415 MHZ per second used for data transmission, which can easily penetrate over three floors of a building and go over 30 feets in open space.
1.7 PROJECT REPORT ORGANIZATION
The organization of the project report is well detailed and vast in its coverage. It covers all the activities encountered during the research work as shown in the block diagram below.
Fig 1.1: PROJECT ORGANIZATION BLOCK DIAGRAM
The first chapter is the introductory chapter, which covers the background, project objectives, scope of the project, constraints and block diagram overview of the states. Chapter 2 presents the literature review. Chapter 3 covers the system analysis and design including the design methodology in block diagram form. Chapter 4 presents the system implementation, which shows the component layout, the wiring schedule, the wiring diagram and the complete schematic diagram. Chapter 5 covers the testing and integration of the project design. The system testing was first carried out in a laboratory. Chapter 6 is the summary and conclusion, which includes the summary of achievements, problems encountered during project design, recommendation and suggestion for further improvement.
BLOCK DIAGRAM OF THE TRANSMISSION BETWEEN THE TRANSMITTER AND THE RECEIVER
IMAGE HERE
Fig.1.2. Basic idea of a transmitter and receiver transmission using RF.
With the aid of a simple, low cost microcontroller based heartbeat rate and temperature measuring device with LCD output. The heartbeat rate of a patient is measured from the index finger or the wrist or neck using IRD infrared device sensors and the rate is then averaged and displayed on a text board LCD.
The device sounds an alarm when the heartbeat and body temperature exceed the safe threshold value. The programmer stipulates this threshold value at the time of programming of the microcontroller. The threshold value given for the device is between 20 to 120 pulses per minute for heart beat indication and 18 degrees Celsius to 38 degrees Celsius for temperature.
| ABSTRACT
This project shows the construction of a microcontroller based security door using smart card. It is aimed towards programming the microcontroller to control the hardware in sliding door. The system consists of a microcontroller 89S52 which sends a signal to the multiplexers on insertion of the smart card in the card slot. The multiplexers consist of ICS which prompts for a display of the identity of the card user in the liquid crystal display LCD. The LCD displays the status of the card. On validation of the card, the LCD displays a welcome note to the user and prompts for a pin code. The pin code is being keyed in from the key pad. If confirmed by the program written into the microcontroller access will be granted, otherwise no access, giving the user two more chances to insert the correct smartcard or pin code to it, before final denial of access and alarm. When access is granted, the card sends a 5volt signal to the microcontroller which triggers relay, resulting in the opening of the door.
CHAPTER ONE
1.0 INTRODUCTION
Creation of secured access path to offices, homes, hotels, industries etc. has been a successful discovery of man. As a result of this, it has been possible to create door/gates that are well secured using smart card.
Individuals are becoming more aware of the dangers/ risk associated with relying on keys or padlocks to provide security to unauthorized areas of their apartments. Fraudsters/criminals can forge keys or make master keys that will be used to break into such rooms or offices.
To eliminate this insecure and old fashioned method, the use of password in doors/gates mechanism evolved. The development of single secret authentication such as password is an effective security control.
A long password of more than ten characters that consists of random letters, numbers and special character can be very difficult to crack. Unfortunately, users cannot always remember the sort of password, partly due to fundamental human limitations.
Two factor authentication i.e. System that uses card and pin code for authentication overcame the issues of single secret authentication by the requirement of a second secret. Two factor authentication uses a combination of the following items;
Something that the user has, such as hardware token or a smartcard.
Something the user knows, such as personal identification number pin.
Hence to reduce or eliminate the access of unauthorized personnel into unauthorized areas, an automated door/access path is to be constructed. This involves controlling the doors/gates by an artificial means artificial intelligence. It involves the application of automated system that is incorporated into these doors/gates for efficient and optimum performance.
This project was constructed using microcontroller for better creativity and beauty in design. The microcontroller programmable has series of instruction fed into it, this help it to accomplish most intelligent task like the human brain. These include detection of card, identification of password, displaying access granted, access denied and opening and closing of door/gate with the aid of the smart card. An electromagnetic relay controls the opening and closing of the door/gate which is moved to and fro by a synchronous motor DC.
The microcontroller based security door using smart card is designed using the 89S52 microcontroller with appropriate software package. The project is segmented into different module which includes; the mechanical, electrical/electronic and programmable computerized part as listed below;
1. The microcontroller module
2. The keypad module
3. Electromagnetic relay
4. The display unit module
5. The Smart card module
6. The alarm signal module
7. The sliding door/gate
8. Electric motor
9. The Power Supply Module etc.
The microcontroller: The microcontroller does most of the addressing and instruction execution through its data, address and control busses.
The Keypad: The keypad is used for selection i.e. As an input device to issue instruction to the control processing unit CPU of the processor.
The smart card and its associated pin: provide the security system.
The Display Module: the display module shows the output of events that are taking place.
The Electromagnetic Relay: The help of the relay is utilized by the CPU to switch the motor ON which moves or turns causing the gate/door to slide to the defined direction.
The Alarm Unit: The alarm unit produces an alarm signal when a wrong password or pin code is entered more than three times.
The power supply Unit: The power supply unit supplies a voltage for optimum operation of the circuit.
In all, this project demonstrates the integral function of what is obtainable in real system.
1.1 AREAS OF APPLICATION
This project is applicable in areas where unauthorized personnel are restricted from access as can be seen in
Offices
Hotels
Residential quarters
Banks
Security System
Credit or ATM cards
Authorization card for pay television
Sims for mobile phones
1.2 AIMS AND OBJECTIVES
The major aim of this project is to construct a system that uses two factor authentication smart card and their associated pins to provide security control to reduce the threat of authorized access to some restricted areas. It also aims at bridging the technological gap between developing and developed countries of the world. | CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
This research is on Design and construction of 20watts wireless public address system. A public address system allows you to broadcast information to a large group of people, whether you are giving a speech or playing live or recorded music. Public address systems typically consist of input sources, preamplifiers, control and monitoring equipment, and loudspeakers. Input sources refer to the microphones that provides a sound input for the system. These input sources are fed into the preamplifiers. The pre amplified signals are then passed into the audio power amplifiers.
These amplifiers will amplify the audio signals to an adequate speaker line level. In view of the above, one can now say that the public address system is an electronic amplification system used for communication in public areas.
Microphone is a device that converts sound waves into electrical waves. Some times colloquially called a micro mike is an acoustic to electric transducer or sensor that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, live and recorded audio engineering, in radio and television broadcasting and in computers for recording voice, and for non-acoustic purposes such as ultrasonic checking. The sensitive transducer element of a microphone is called its element. Since a wireless microphone is used in this project; a wireless microphone is one in which communication is not limited by a cable.
IMAGE HERE
Fig2:A transmitter circuit
The first transistor Q1 is the preamplifier for the microphone, and you can omit this circuit if you don't want to transmit the sound picked up by the mic, for example you can connect your mp3 player directly to C1. The core of this FM transmitter circuit is Q2, a modified Culprits oscillator that the frequency is determined by L1, C4, C6, and the transistors internal base emitter capacitance. The antenna use 1/16 wave length to compromise between the efficiency and the size. If you want the microphone to be less sensitive, we can replace the R1 by a higher resistor, such as 10k or 22k, and this might overcome the feedback problem if you use this wireless microphone FM transmitter for a public address system
1.2 AIMS AND OBJECTIVES
Public speaking is the process of speaking to a group of people in a structured, deliberate manner intended to inform, influence, or entertain the audience. In public speaking, as in any form of communication, there are five basic elements, often expressed as who is saying what to whom using what medium with what effectsW.Kleitz;2005 pg134.
The major objective of this project is to design and construct a public address system with relatively unique operational characteristics that is capable of delivering 20 watts of electrical power into an 8 Ohms load loudspeaker. This will be achieved with adequate tone controls and mixer stages so as to enable communication or reproduction of speech and recorded music in buildings and institutions.
1.3 JUSTIFICATION
Over the ages, science and technology has been developing with new inventions in various fields; including the increase in modifications on existing technology all gearing towards improving effectiveness and reliability of equipment and achieving to a great degree miniaturization and optimal cost.
This project is backed by my interest in the area of electronics and communication, and having been groomed to a great extent with introductions into the various fields of electrical and electronics engineering, with the knowledge in principles of telecommunications, telecommunication engineering,
1.4 SCOPE OF THE PROJECT
This system is for public address; it has an estimated power rating of 20watts. For power supplies, it uses a 220/12Vac transformer for the receiver, amplifier and loudspeaker units. It has a power On/Off button with volume control.
1.5 SYSTEM BLOCK DIAGRAM
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Fig 3: Block diagram of a public address system
The system is made up of the transmitter which is incorporated in the microphone; and the receiver unit, the tone control and mixer unit, the audio amplifier unit and the loudspeaker.
1.6 PROJECT WORK ORGANISATION
The various stages involved in the development of this project have been properly put into six chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:
IMAGE HERE
Table 1 : Project work organization |
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