DESIGN AND IMPLEMENTATION OF AN ELECTRONIC SIGN PATTERN DISPLAY

ABSTRACT

This design implementation of this electronic sequential sign post display employs the use of some specialized components. This section of the project introduces the reader to the different section of the project and the components that makes them up.
Emphasis are laid on describing the behaviour and operational system of the components as related to the project modeling, analysis, design and implementation of an ELECTRONIC SIGN POST, which is made up of a power supply, a shift register, a counter, multivibrator (555CMOSI.C) transistor, relay, resistors of different ohmic values capacitors, sensitive mic (for the switching system) and 220V AC lamp.

CHAPTER ONE

INTRODUCTION
DESCRIPTION/FUNCTIONS OF THE COMPONENTS USED IN THE PROJECT
1. POWERS SUPPLY/TRANSFORMER
The power supply is culmed produce power required by the component to function. It coverts line voltage which is AC to DC and to a level that can be used by the various components. This is achieved by the use of a step down transformer to step down rectify, filtrate and regulate the line voltage.

CIRCUIT SYMBOL
THE SHIFT REGISTER
The shift register is a serial-in, parallel out register, it is responsible for the display “WELCOME TO ELECT/ELECT DEPT.” WELCOME” comes up frist, after some time interval which will be determined by the 1MSO resistor or a variable resistor “TO” come up, followed by “ELECT/ELECT” and finally “DEPT”.
The process is repeated, The counter is a decade counter with a decorded outputs. It controls the boarder display pattern in the form of light laser pattern.
The rate at which the lights display is determined by the frequency of the 55C1MOS timer chip which acts as a clock generator that generates square wave to the counter.
Hence, the timing of the whole circuit is controlled by the four 555CMOS I.C. in the circuit. Each timer controls the sequence of each lamp at the terminal with the help of the relay drive.

CIRCUIT SYMBOL
RELAY
A simple relay is made from a coil of wire wound around a soft iron core with the ends of this coil at erminals, when it is energized the soft iron core become a magnet and attracts the armature.
The working principle of simple normally open relay found a wide application in this circuit for the switching “ON” and “OFF” of the lamps.
TRANSISTOR
This is another three terminal semi-conducting device. It is basically made of N-type material and P-type material.
A simple transistor is of two types namely:
NPN transistor and
PNP transistor
A transistor always performs two or more functions in a circuit, it can either function as:
1. An amplifier
2. A switch.
This functions depends on how it is connected in the circuit. In this work, we are going to dwell much on it’s function as a switch.
The output squared wave signal from the timer is fed to the base of the PNP transistor this signal suffers several venations at the function of the transistor. Finally, passed through the emitter of the transistor to trigger the relay as required.
CIRCUIT SYMBOL
DIODE
This is a semi-conductor device that allows current to flow only in one direction, (depending on how it is connected in the circuit). It can be connected in either forward or reverse direction.
CIRCUIT SYMBOL

A SIMPLE DIODE

CAPACITOR
In it’s simple form, it is just a device or component which is used to store electronic charge. It is known by its charging and discharging principle. When it is connected current will flow into the capacitor until it is full then it discharges gradually.
The two types known are:
1. Fixed capacitor
2. Variable capacitor under fixed we have
a) Electrolytic capacitor (polarized)
b) Non-electrolytic capacitor (non polarized)

CIRCUIT CONNECTION
A capacitor can be connected either in series or in

parallel. When connected in series, the equivalent

connection is this CT = 1 + 1 + 1 + 1 + 1 ————- 1
CT C1 C2 C3 C4 Cn
When connected in parallel, the equivalent connection is thus:
CT = C1 + C2 + C3 + C4 ——————————Cn.
The S1 unit is farads “F”.
CIRCUIT SYMBOL

RESISTOR
This is the most commonest component found in an electronics circuit.
It is a device that offers opposition to the flow of electric current. The amount of opposition depends on the ohmic value of the resistor.

TYPES OF RESISTOR
Just like capacitors, we have types of resistors
1. Fixed resistors
2. Variable resistors.
Both fixed and variable have no polarity, it can be connected in either way round.

CIRCUIT CONNECTION
It can be connected in either series or parallel. When connected in series the equivalent connection is thus:
RT = R1 + R2 + R3 + R4 ————————– Rn
While when connected in parallel, the equivalent connection is thus:
RT = 1/R1 + 1/R2 + 1/R3 + 1/R4 ——— 1/Rn
CIRCUIT SYMBOL
OR
As we all know that every good work deserves favour, Advertising by ordinary sign post as a means of promoting business in Nigeria has suffered neglect as far as benefit from increasing sophistication in the electronics industries is concerned.
This project was undertaken to give a lasting solution and establish electronic sign post as a useful means of advertising any time of the day (day/night). Such electronic sign post give life on advertisement and promotes security purposes.
For security purposes, intermediate display can be used to easily draw the attention of possible victims to avoid danger. For example “DANGER” “KEEP” “OFF”.
“STOP”
“SLOW DOWN”
“HARZARD ZONE”.
The same principle is also applicable in the implementation of traffic light and other related control system.
In advertisement, the entertainment of words related to business enterprises or organization displayed in a digital pattern attracts the attention of people and possible customers.
Previous works done on display system used integrated circuit for system control. Some also used discrete components, but for the sake and ability to use both integrated circuit and discrete components together a more functional display pattern was achieved. Some system use an arrangement of light emitting diode inform of a lettered word. This (LED) light emitting diodes are arranged either in parallel or series form in such a manner that they illuminate to display a series of lettered word.
A disadvantage now emerged in the sense that the break down of one light emitting diode will automatically effect the rest ones. To overcome this short coming, we decided to make use of 220V discharge lamp which could be easily rectified in terms of fault.

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