DESIGN AND CONSTRUCTION
The aim of this project work is to design and construct an electronic digital display system, based on light-emitting diodes connected in an array that forms the information to be displayed i.e. “GREAT NIGERIAN STUDENTS”. This project is useful for creating attention – getting messages, presentations, advertisements and location identifiers. The system consists of power supply unit, oscillator unit, counter unit, driver unit and output unit. The power supply unit uses alternating current (AC) from the mains which will be stepped down to 12V using a step-down transformer, rectified with bridge rectifier, filtered with the actual capacitor and regulated to 9 volt using an IC regulator. The oscillator unit contains a 555 timer IC set as astable multivibrator used to produce clock pulses for the counter unit which contains 4017 decade counter IC. The 4017 counter enables the information to be displayed sequentially as desired. The driver unit uses transistor to amplify the signal strength of the counter’s output. The output unit enables the information to be displayed using light emitting diodes (LEDs).
Table of Contents
Table of contents
List of plate
List of table
List of figures
CHAPTER ONE: INTRODUCTION
1.1 Background of the problem
1.2 Statement of the problem
1.3 Objectives of the study
1.4 Significance of the study
1.5 Scope of the study
1.6 Research questions
CHAPTER TWO: LITERATURE REVIEW
2.1 Component description
CHAPTER THREE: MATERIALS AND METHODS
3.1 Power supply unit
3.2 Oscillator unit
3.3 Counter unit
3.4 Driver unit
3.5 Output unit
3.6 Description of Electronic Digital Display System
CHAPTER FIVE: DISCUSSION, CONCLUSION AND RECOMMENDATION
Cost of Construction
List of plate
Plate 1: The photograph of the constructed electronic digital display system
List of tables
Table 1: Experiments carried out and their frequency
List of figures
Fig. 2.1: Symbol of a transformer
Fig. 2.2: Circuit symbol of bridge rectifier
Fig. 2.3: Symbol of a polarized and non-polarised capacitors
Fig. 2.4: Symbol of a diode
Fig. 2.5: Symbol of a LED
Fig. 2.6: Circuit diagram of rectifier diode and LED connected in
Fig. 2.7: Pinout connection of 7809IC
Fig. 2.8: Symbols of fixed and variable resistors
Fig. 2.9: Symbols of transistor
Fig.2.10: Pinout diagram of 555 timer
Fig.2.11: Pin connection of 4017 decade counter
Fig.2.12: Diagram of a veroboard
Fig. 3.1: Block diagram of electronic digital display system
Fig. 3.2: Circuit diagram of full wave rectification
Fig.3.3: Circuit diagram of a 9 volt regulated power supply
Fig.3.4: Circuit diagram of astable multivibrator
Fig.3.5: Complete circuit diagram of electronic digital display
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”