AN ELECTRONIC DIGITAL DISPLAY SYSTEM

AN ELECTRONIC DIGITAL DISPLAY SYSTEM

CHAPTER ONE

1.0 INTRODUCTION

In modern times, the use of solid state materials has helped man enjoy his existence by the wonderful innovation in the world of electronics. One major development that has made possible the enormous advancement in solid state technology is the digital revolution. Circuits are designed to implement the basic

digital logic functions fundamental to all digital systems. Digital electronics therefore compasses the design, manufacture, and use of circuits for processing information in digital form (Obiechine, et al., 2013). An information display is a way of providing information object for promotion. It can be seen in a form of cardboard or tarpaulin at stores/shops, streamers and electronic display devices. The advent of new technologies made the information display in form of Electronic displays most common nowadays especially for advertisements and promotions (Wilbert, 2007). The development of information display electronic

based system has covered numerous technologies since its beginnings (Gowrishankar, Mritha, & Chandra, 2014). Display technologies have been developed for many years. In the late twentieth century, cathode Ray Tube

(CRT) dominated the market. However, new trends in display include the demand of picture quality, size and power consumption. So, Liquid Crystal Display (LCD) is then emerging to be the current market. Due to their relatively light weight, low operating power and compact design, LCD has become a popular part of home entertainment system and it continues to dominate the existing market (Chan, Cheungkaki, & Mak, 2011). Traditional LCD requires colour filter to display full

color. Electronic display devices nowadays are mostly controlled by a microcontroller. And the semiconductor that gives out light like an LED has been a great breakthrough in electronic display (Baron, 2011). Field

Sequential Color of LCD (FSC-LCD) generates full color without color filters, with the use of colour addition. Despite existence of numerous implementation of

embedded system coding, designing a digital sequential display system (DSDS) is still considered as one of the innovative implementation (Bhagyashree, 2009). This

technology (DSDS) can be found in a number of places and are being used for different purposes. In banks, it is used to display interest rates as well as exchange rates, in hotels and pubs; it is used to display menu and prices

(Obiechine, Don, & Uche.V, 2013). The extent of development in information dissemination has made it possible that the well-known method of displaying information using sign posts, placards, notice boards, etc. has to be modified by using electronic information board. In previous years, the means by

which adverts, information, etc., are made has been through the method of the digital display board. But the use of static mode of sign display such as banners, flyers etc. are becoming boring and unattractive. The new technologies of the digital age have made possible the use of programmable and reprogrammable electronics display to provide solutions to this kind of problem

(Obiechine, Don, & Uche.V, 2013). National Open University of Nigeria (NOUN), Ado-Ekiti centre does not have a welcome digital display as at the time of this

research work; therefore, it is pertinent to design a digital display in order to fulfill this need.

A brief history of Digital Billboards and the tech behind them.

JG Ballard Digital Billboards Atlanta In 1963, author J.G. Ballard predicted the use of enormous electric signs to entice people to “buy now” in a short story entitled, The Subliminal Man. Today, digital billboard advertising is very much a reality utilized by small and large corporations across the country. According to the Outdoor Advertising Association of America, digital billboards made their first actual appearance in 2005 as both screen and Internet technology became available to make the remote loading of files possible onto a billboard-sized screen. However, prior to the first electronic billboard, digital place-based screens had been in use since the 1990’s. The science behind how electronic billboards work is pretty simple: advertising messages rotate every six to eight seconds on an LED screen. Controlled remotely, this advertising option is best-suited for companies in need of more flexibility in their ad messaging. Created in a similar way to ads on traditional billboards, the key difference is in ad delivery. Digital billboard advertising is sent out as a simple .JPEG file rather than printed and pasted directly to the billboard.

1.1     Background of the study

Electronic digital display system as used in this reports refers to a sign that uses electronic hardware and software to display its copy, messages or images. Also, a sign utilizing a fixed light source to provide a message in text, images pictures, and or symbols that may appear to move or may appear as on/off messages. This is contrast to traditional non-electronic signs where the copy displayed is physically applied to the sign surface by printing, painting or otherwise attaching it onto the sign. The materials or substrate to which the copy is applied is typically paper, wood, plastic or the wall of a building. In this modern time, solid materials have helped man to show that he really exists by doing wonders in the world of electronics. One major development, made possible by the enormous advances in solid state technology, is the “digital revolution”. Circuits are designed to implement the basic digital logic functions fundamental to all digital systems. Digital electronics therefore comprises the design, manufacture and use of circuits for processing information in digital form (Simpson, 1978).

An information display is a way of providing information and it is also used as an object for promotion. It can be seen in a form of cardboard or tarpaulin at stores / shops, sign posts, placards, notice boards and electronic display boards. But the advent of new technologies has made the information in the form of an electronic display in the world of advertisements and promotions (Gupta, Shukla and Nagwekar, 2013). The ability to display a short message can be useful application to be available for any business. Electronic digital display system is perfect for this application. It can be used for both indoor and outdoor which makes it universal fit for any business or event. Electronic digital display system is very efficient and cost effective way to spread messages to thousands of people, without any personal contact or door to door sales. Light-Emitting Diode (LED) is a solid state light source with several attractive properties for display application. LED is a diode that gives off visible light when forward biased (Mehta and Mehta, 2014). It is chosen as the main component for displaying messages because, today LED is the most energy efficiency example and other useful systems.

The birth of signs and display can be said to be as old as the existence of man on the planet earth. From the beginning of the world, different types of displays have been in use, each mode to serve the purpose of invention efficiently. Signs are any kind of visual graphics created to display information to a particular audience (David, 2013). In 1389, King Richard II of England compelled landlords to erect signs outside their premises (Manton, 2008). In ancient Rome, signboards were usually made from stone or terracotta (Chris, 1995).

With the advancement in technology, man started carving woods and trees. The use of special dyes on wood as a means of identifying special locations. With the discovery of Bronze and iron, man started using the materials to display sign, thus the advent of metal sign boards were born, which are mostly used in developing countries. On semiconductors and vacuum tubes technology, light displays and sign boards were built to add more beauty in the old system and as a way to increase visibility. LED technology is frequently used in signs now instead of Neon signs, introduced in 1910 at the Paris Motor show (Bellu, 2006). The use of electronic is now becoming very important. It is extensively applied in almost our day to day activities.

Electronic digital display system is also used for outdoor advertisement. Before, outdoor advertising was mainly characterized by the use of paper. Every bus stop and billboard had a paper advertisement inside. The reason for this was simple paper was easy to use and extremely cheap. It had some draw backs as well. Before an image is actually on the street, it first has to be printed, pasted and placed. The journey from design to placement is quite long. Another disadvantages is the considerable amount waste generated by the use of paper. Finally, many people ignore a paper advertisement and there attention is drawn to the vibrant environment around them and not to a still image.

The extent of development in information dissemination has made it possible that the well known method of displaying information using sign posts, notice boards, etc has to be modified by using electronic digital display system. In today’s rapidly advancing technology market, most conventional digital display system are not being implemented using individual logic gates and integrated circuits (ICs) such have been used in the past instead, programmable devices such as microprocessor and microcontroller chips which contain the circuitry necessary to create logic functions are being used to implement digital systems. The use of 555 timer as a stable multivibrator and decade counter (CD4017) can be used to build less expensive electronic display system. The use of these two major ICs will bring about less board space, less power consumptions and overall, low cost in manufacturing.

This project however; emphasizes mainly on the display of information using two major integrated circuits (ICs) namely NE555 timer (ICI) and CD4017 (IC2) to control the lighting of LEDs. This message display circuit is built around readily available, low cost components. It is easy to fabricate. A total of 250 LEDs will be used to display the message “GREAT NIGERIAN STUDENTS”

1.2     Statement of the Problem

Due to limitation of the sign board or local sign board which could not display clearly at night expect light shines on it, it is then necessary that electronic display system is employed to counter the limits of the local sign board. The information displayed on the local sign board is less attractive compared to the information displayed using electronic digital display system.

Thus, researchers are prompted to tirelessly hold up to these challenges by initiating some means of improving the above among which is the design and construction of an electronic digital display system.

1.3    Aims and Objectives of the Study

The main objective of this study is to design and construct an electronic digital display system. Specifically this study will achieve the following:

i. To display “WELCOME TO AJAYI POLYTECHNIC”

ii. To use the electronic digital display system constructed as a sign post for Ajayi polytechnic

iii. To have more knowledge on what electronic digital display system is all about.

v. To know the benefits of electronic digital display system.

v. To design and realize the moving message display panel.

1.4     Significance of the Study

In all field of human endeavor, electronic digital display system plays very vital role, such as means of advertisement, means of communication, presentations, exhibitions, identification and direction. It is also used in giving warning or safety instructions, such as warning signs, traffic signs, exit signs or signs conveying rules and regulations. This project write-up will be a guide to future designing in a related work.

1.5     Scope of the Study

This project covers the use of peripheral solid state electronic components alongside with two major integrated circuits (ICs) namely NESSS timer and CD4017 decade counter to solve above stated problems. It is limited to display WELCOME TO AJAYI POLYTECHNIC

CHAPTER TWO

LITERATURE REVIEW

There are many works that have been carried out on digital electronic message display board for application in different spheres of life.

Nivetha, et al. (2013) designed and implemented an SMS based wireless notice board with monitoring system. This project was designed using integrated circuit (IC4017) which will sends signal to IC 7432.

An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave, Oscillators convert direct current (DC) from a power supply to an alternating current (AC) signal. They are widely used in many electronic devices ranging from simplest clock generators to digital instruments (like calculators) and complex computers and peripherals etc. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games. Oscillators are often characterized by the frequency of their output signal: A low-frequency oscillator (LFO) is an electronic oscillator that generates a frequency below approximately 20 Hz. This term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator. An audio oscillator produces frequencies in the audio range, about 16 Hz to 20 kHz.

An RF oscillator produces signals in the radio frequency (RF) range of about 100 kHz to 100 GHz. Oscillators designed to produce a high-power AC output from a DC supply are usually called inverters. There are two main types of electronic oscillator – the linear or harmonic oscillator and the nonlinear or relaxation oscillator.

A sequential digital display

A sequential digital display is an electronic system that is used to display information to the public. It is a device that contains light emitting diodes that conveys messages by a programmable controller or mechanical processes, regardless of size. Sequential digital display is fast gaining acceptance and application in different spheres of life. In this work, a sequential digital display system was designed and implemented. The components used include transformer, diodes, voltage regulator, resistors (fixed and variable types), capacitors, NE555 timer, IC4017, light emitting diodes and transistors ( Wikipedia, 2016)

Counter unit

In digital logic and computing, a counter is a device which stores (and sometimes displays) the number of times a particular event or process has occurred, often in relationship to a clock signal. The most common type is a sequential digital logic circuit with an input line called the clock and multiple output lines. The values on the output lines represent a number in the binary or BCD number system. Each pulse applied to the clock input increments or decrements the number in the counter. A counter circuit is usually constructed of a number of flip-flops connected in cascade. Counters are a very widely used component in digital circuits, and are manufactured as separate integrated circuits and also incorporated as parts of larger integrated circuits. ( Wikipedia, 2016)

Driver unit

In electronics, a driver is a circuit or component used to control another circuit or component, such as a high-power transistor, liquid crystal display (LCD), and numerous others. They are usually used to regulate current flowing through a circuit or to control other factors such as other components, some devices in the circuit. The term is often used, for example, for a specialized integrated circuit that controls high-power switches in switched-mode power converters. An amplifier can also be considered a driver for loudspeakers, or a voltage regulator that keeps an attached component operating within a broad range of input voltages. Typically the driver stage(s) of a circuit requires different characteristics to other circuit stages. For example in a transistor power amplifier circuit, typically the driver circuit requires current gain, often the ability to discharge the following transistor bases rapidly, and low output impedance to avoid or minimize distortion. ( Wikipedia, 2016)

Electronic bill board

Electronic billboards are high-tech versions of the traditional billboards that are often found along highways and major thoroughfares within some cities. The main function of this type of billboard is to advertise goods and services, or provide announcements or promotions to the general public. A single electronic billboard may offer a rotating selection of ads for a single entity, or be used to display advertising for multiple companies on a rotating basis. Some of the earliest efforts to develop this form of mobile advertising produced results that were somewhat like a theater marquee. Text and simple illustrations that were created using projection equipment were considered novel, but not particularly cost effective. As technology continued to advance, the development of rear-projection equipment and the ability to control the multiple displays from a central control unit enhanced the quality and range of the displays, while also making them much easier to load and unload. One of the advantages of an electronic billboard is that the advertising no longer has to be static. Depending on the source of the imaging on the display, the experience may be somewhat similar to that of watching a commercial on television. However, the visual display may offer something simple, like animated graphics that allow the billboard to present a simple ten second message that repeats continually, making it possible for anyone passing by to view the entire message with relatively little effort. In addition to the enhanced options for visual display, companies that operate the billboards can also maximize their return on a single electronic billboard. Since it is possible to display an ever-changing rotation of ads for different clients, one billboard may advertise goods and services for several clients throughout the day. Advertisers sometimes like this approach, since it allows them to purchase a certain amount of advertising time each day, without having to pay for the full use of the board around the clock. While it is likely that the use of electronic billboard advertising will increase over time, there are some obstacles that may limit the use of this medium in some settings. Because many operators of the boards use remote control equipment to load and change displays, some of the regulations that apply to wireless communications are likely to apply to the operation of the billboards themselves. In addition, there is some concern that the movement on an electronic billboard is more distracting for people driving by the displays, a fact that could lead to an increase in vehicle accidents. For this reason, some jurisdictions are likely to impose limits on what intersections and stretches of highways that the boards can be placed. https://m.wisegeek.com/what-is-an-electronic-billboard.htm

Microcontroller unit

A microcontroller (MCU for microcontroller unit) is a small computer on a single integrated circuit. In modern terminology, it is similar to, but less sophisticated than, a system on a chip (SoC); an SoC may include a microcontroller as one of its components. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals. Program memory in the form of ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips. Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes. Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems. In the context of the internet of things, microcontrollers are an economical and popular means of data collection, sensing and actuating the physical world as edge devices. Some microcontrollers may use four-bit words and operate at frequencies as low as 4 kHz, for low power consumption (single-digit milliwatts or microwatts). They generally have the ability to retain functionality while waiting for an event such as a button press or other interrupt; power consumption while sleeping (CPU clock and most peripherals off) may be just nanowatts, making many of them well suited for long lasting battery applications. Other microcontrollers may serve performance-critical roles, where they may need to act more like a digital signal processor (DSP), with higher clock speeds and power consumption. https://en.m.wikipedia.org/wiki/Microcontroller

Obiechine, et al. (2013) designed and constructed a dot matrix information display for the office of the vice chancellor, Anambra State University, Uli. It was done in three stages namely the design, construction and working of a dot matrix information display. The project covered a fairly comprehensive study of a dot matrix information display. Digital instruments, signals, and related numbers and codes were discussed. The project was designed such that the dot matrix information display operates with electrical power from either direct or alternating current source.

Emilo (2010) also designed 15 LEDs by 7 LEDs scroll message advertising billboards, this project uses 105 LEDs to produce a screen 15 LEDs long, by 7 LEDs High for running messages. Larger displays showed more letters but this is the largest display that can be produced with a single PIC16F628 micro.

 Ketkar, et al. (2013) designed and implemented a LED scrolling message display system. The system hardware consists of an AT89C51 controller which serves as the heart of the system. The inclusion of the buzzer and alarm units into

the design limits its area of application and makes thesystem unduly complex.

Ukpa, et al. (2013) developed a SMS Controlled Digital Display System using multiple microcontrollers namely PIC16F877 and PIC16F628 and a SAGEM MYX5-2 phone.

Dresden (2008) designed and implemented alternative transparent electrodes for organic light emitting diodes (OLED). In his work, he studied the use of two types of alternative transparent electrodes, ZnO: AL and PEDOT. These were developed for organic OLEDs. The evolution of light bulbs in the 1880s brought about the use of electric lighting as a standard technology. The use of flourescent and incandescent lamps has dominated the world today because of their low cost and long-term stability. Solid state lighting (SSL) is a new environmental friendly light source with potentially high efficiency. So far, LEDs and OLEDs have been presented as candidates for solid state lighting

(Alstair, 2013). Several view-sequential displays have been demonstrated by developers which implement a time multiplexing principle and utilize a fast optical

modulator, active shutters, and projection optics. Time sequential information is angularly multiplexed by restricting the pulp of a projection system in conjunctions with images being displayed on the modulator

(Philip, John, Phil, & Christopher, 2007). Sequential systems have the advantage of using a single modulator, which is more economically feasible than other multi-view systems. They also provide natural reviewing zone, which is a subject of difficulty for other multi-view displays. However, they require large projection optics, which limits the field of view. They also throw away a lot of light because of the active shutter, which are included in the system.

CHAPTER THREE

SYSTEM DESIGN & ANALYSIS/METHODOLOGY

3.0 MATERIALS AND METHODS

Descriptions of components used in the design are explained in following sub sections.

3.1 TRANSFORMER

A transformer works through the principle of magnetic induction. It is a device that converts an alternating (A/C) current of a certain voltage to an alternating

current or direct current of different voltage, without change of frequency, by

electromagnetic induction. The functions of the transformer in the circuit are:

1. To step down the input voltage from 220v to the required 15v of the designed circuit.

2. Transformer allows high Voltage to be stepped down to lower Voltage.

3. It also allows the circuit diagram to be isolated from mains

Figure 3.1 the symbol of transformer

3.2 DIODES

Diodes used in this work were used to perform rectification after the transformer had stepped down the voltage to 15volts. The diodes convert AC to DC

enabling components operating on DC to be powered. The specifications of diodes used are the IN4007 and IN4148.

Figure 3.2 the symbol of diode

3.3 VOLTAGE REGULATOR

The purpose of the voltage regulator is to get a fixed output voltage irrespective of the input voltage to the system. Various voltage regulators exist but the one used

in this work is specified as LM7812 which gives a constant 12V DC supply to power the circuit. LM7812 have three-terminal devices that provide a

constant DC output voltage that is independent of the input voltage, output load current, and temperature. The IC does not require additional components to provide a constant, regulated source of power, making them easy to use, as well as economical and provides efficient use of space. Other voltage regulators may require additional components to set the output voltage level, or to assist in the regulation process. They have protection against overheating and short circuits,

making them quite robust in most applications. In some cases, the current-limiting

features of the LM7812 devices can provide protection not only for the LM7812 itself, but also for other parts of the circuit.

3.4 RESISTORS

The resistor acts as a passive component that resists the flow of current. The resistors available include such ratings as 10KΩ, 330Ω, 1MΩ, 220Ω, 100KΩ,

1KΩ, and 1MΩ variable resistor. However, a 1KΩ resistor was used for the project.

Figure 3.4 the symbol of resistor

3.5 CAPACITOR

The capacitor is used to allow AC signal to pass to the input of the timer integrated circuit (IC) while the DC signal is blocked. The capacitor used in the power circuit

of this project is to filter the ripples that may be found in the power supply section and in the switching stage. The specifications used in this work are 100μf, 10nf, 1nf. Various types such as electrolytic capacitor, ceramic capacitor and mica capacitor were deployed.

Figure 3.5 the symbol of capacitor

3.6 TRANSISTOR

A transistor can be used to amplify weak signal and also act as a switch. In this work, however, the transistor used IC D888 (NPN) is used to amplifier weak signal

Emanating from the IC 4017.

Figure 3.6 the symbol of Transistor

3.7 NE555 TIMER

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 timer can be used

to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package. This multipurpose IC NE555 is

wired as a stable-multi vibrator which detects the signal coming to its input.

Figure 3.7 the symbol of NE555 timer

3.8 INTEGRATED CIRCUIT 4017

The IC 4017 can be considered as one of the most useful and versatile chip having numerous electronic circuit applications. Technically it is called the Johnsons 10 stage decades counter divider. The name suggest two things, it has something to do with number 10 and counting/dividing. The 555 IC will operate in astable mode with a frequency of 14Hz. The 555 IC in the

circuit is used as a clock pulse generator to provide input clock pulses to the counter IC 4017. The IC 555 in the circuit operates at a frequency of 14Hz, which means that it produces about 14 clock pulses every second to

the IC 4017. The clock pulses generated at the output of IC 555 timer (PIN-3) is given as an input to IC 4017 through PIN-14. This is shown in figure 1.

Whenever a clock pulse is received at the clock input of IC 4017 counter, the counter increments the count and activates the corresponding output PIN. When count is zero, PIN-3 is HIGH, which means LED-1 will be ON

and all the other LEDS are OFF. After the next clock pulse, PIN-2 of IC 4017 is HIGH, which means that LED-2 will glow and all the other LEDs can be turned OFF. This repeats and the LEDs turn ON and OFF successively on each clock pulse thereby producing circling effect

Figure 3.8: the diagram of integrated circuit 4017

3.9 INTEGRATED CIRCUIT 7432

The schematic diagram of the IC 7432 used in this work, pin 1 and 2 are the inputs of first gate where the output is from pin

number 3. Pin number 4 and 5 are the inputs of second gate whose output is in pin 6. Pin 10 and 9 are the inputs of fourth gate whose output is at pin 8. The input of the last gate or fourth gate is pin 13 and 12 and pin 11 is its output. Pin 7 is ground and pin 14 is +Vcc supply

3.10 LIGHT EMITTING DIODES (LEDS)

Light emitting diodes are semiconductor devices that illuminate solely by motion of electrons. When forward biased, these components emit light. LEDs provide a

cheap and convenient way to display information electronically, fit easily into an electrical circuit, and are durable. LEDs were designed with different colours:

RED, BLUE. WHITE, GREEN and PINK etc for the purpose of this project YELLOW were used. The circuit diagram showing all the components used is

Figure 3.10 the symbol of light emitting diode

3.11 THE CIRCIUT DIAGRAM

Figure 3.11 the Circuit Diagram of The System

CHAPTER FOUR

4.0 IMPLEMENTATION

The implementation of the project is divided into four stages which are:

i. Power stage

ii. Input stage

iii. Amplifying stage

iv. Output (Result) stage

4.1 POWER STAGE

The power stage supplies the current needed to power the circuit. This stage comprises of transformer, Diodes, Capacitors, wires and the voltage regulator (7812). The transformer steps down voltage input 220 v to output 15v which is passed to the block diode for rectification, the output produced is DC (Direct current) which still contains some ripples (i.e. unwanted AC signal), the ripples in the circuit if allowed to power a device, may damage the device or may not allow the device to function properly. To avoid this situation, filter capacitor

100μf and 10nf are connected to the output of the block diode to filter the ripples and after the ripples is filtered; the voltage regulator 7812 is then connected to ensure constant output voltage which is 12V as shown Fig 4. A Light Emitting Diode is connected to the output in order to monitor the output power Supply, if voltage is supplied to the output, then the LED glows, and if not, the LED remains in the off position.

Figure 4.1 the power stage diagram

4.2 THE INPUT STAGE

The input stage shown in Figure 5 involves the soldering of the NE555 TIMER, IC 4017, resistors, and capacitor on the Vero board which allows the signal to transmit

to the IC 4017 to control the display of the light emitting diode. The first output of the IC 4017 must be active at the time when the thyristor chip is outputting

the first row of data and this means the 4017 must be "clocked" so that it is turning on the first output at the beginning of the scanning cycle.

Figure 4.2 the input stage circuit diagram

4.3 THE AMPLIFYING STAGE

In this work, thyristors D882 were used to boost the weak signal from the CD4017 so as to be able to control display on the output of the circuit. The first output of

the 4017 must be active at the time when the D882 is outputting the first group of the character e.g. (WELCOME) and this means the 4017 must be “clocked”

so as to turn on the first output at the beginning of the scanning cycle. Figure 6 shows the amplifying stage pictorial view.

Figure 4.3 the amplifying stage diagram

4.4 OUTPUT STAGE/ RESULT

The designed sequential digital display was tested in the polytechnic  environment. It was connected to a 220 volts supply which is stepped down to 12 volts for the circuit. The result showed that the light emitting diodes displayed the title: WELCOME TO AJAYI POLYTECHNIC IKERE EKITI correctly. This is shown in Figure 4.4. In comparison with the work of Emilo (2010) and Ketkar, et al. (2013), this work uses less complex components andcheaper materials to achieve the same results.

CHAPTER FIVE

5.0 CONCLUSIONS AND RECOMMENDATIONS

A moving message display or a scrolling message is an excellent method of communicating information. The smooth sailing effect of the alphabet or the characters is not only pleasing to the eyes, but also, information becomes accessible through a short time passage The design and development of a sequential digital display board was accomplished. Justification for the selection of materials used was given by design calculations. The board is used to display a welcome message for visitors and students in AJAYI POLYTECHNIC IKERE EKITI study centre in Nigeria. Readily available and cheap components were used to execute the project. Further improvement works can be done by introducing matrix board and PIC microcontroller to the project.