The Design and Implementation of a Four Way Traffic Light Control Circuit
CHAPTER ONE
AIM OF THE PROJECT
Going by the rapid advancement in technology all over the world, the need for better ways of solving a problem keep coming up every day. Necessity is the mother of invention. It has become imperative for societies, companies, industries, business ventures, clubs etc to offer 24 hour service, hence thereby has to be a way of controlling the teaming column of vehicles which convey both individuals and goods to different destinations of that type. The most elegant way of directing the motorists is by the use of traffic light control. This type of control serves a dual purpose. In the day type it directs the vehicles, whereas it turns out to additionally illuminating the environment in the night, so that at very far distance, its effect is noticeably felt, conveying its message to an oncoming vehicle very far from the point.
CHAPTER TWO
A REVIEW ON THE TRAFFIC LIGHT SYSTEM
The traffic light system is made up of all the components and circuits used to realize to lighting effect at the output. Basically it consists of the power supply units, the digital logic circuit and components, the power circuit and the traffic light bulbs themselves. Each stage is directly connected to the other such that the last stage gives the desires output.
THE POWER SUPPLY UNIT
Virtually all electronic equipment operates on dc either from a battery or converter from an energy source such as the ac power line. The importance of this stage is to provide a predetermined dc voltage say Vs, which is independent of external actors within the limit of the current, I drawn from it by the load. The power supply unit can be further broken down into the following stages.
THE TRANSFORMER
This transformer or steps down the voltage from the ac powerline to a lower operating ac voltage which is within the range of the voltage required by the logic circuit. The transformer is chosen such that its power rating is higher than the power required by the system it is powering. It is also important to note that the bridge rectifier can safely draw only one half of the transformer’s rated secondary current without exceeding the VA rating of the transformer.
THE RECTIFIER
The rectifier is used to convert the ac from the transformer into a pulsating dc. There are basically many types of rectifiers but the full-wave bridge rectifier which consists of a 4 diode ring is normally employed. It has the advantage of delivering an output voltage of twice that of the full wave rectifier with the transformer secondary centre-tap earthed. Nonetheless the former delivers only half the current of the latter for a given primary VA rating which is suitable for our application.
THE FILTER
The essence of the filter is to smoothen the pulsating dc output from the rectifier into a nearly pure dc required by the electronic circuit. It is basically a resistor connected in series with a capacitor. The capacitor charges and discharges between cycles and hence generates a ripple which approximates a steady dc voltage if the value of the capacitance is high. In practical circuits, the resistor (which is meant to limit the maximum charging current) is usually omitted and the capacitor is connected to the rectifier output since the rectifiers won’t allow the flow back of the currents out of the capacitor to the source.
THE VOLTAGE REGULATOR
A voltage regulator is required to maintain a specific output voltage over various combinations of the input voltage and load. As more load is drawn, the output voltage of an unregulated supply normally decreases. Regulators are normally broken down to shunt regulators and series regulators. The former uses a zener diode as the main regulating device, while the latter employs a power transistor, some resistors and op-amp as error amplifiers, they are normally more efficient.
CHAPTER THREE
THE TRAFFIC LIGHT CONTROL
DESIGN AND CONSTRUCTION
The main objective of this design is to achieve a circuit capable of controlling the lighting of some bulbs/LEDs which are indicative of the next operation a motorist should take at a four way junction. The lighting come on in sequence, reflecting different colours. They are to stay on for a period of time determined by the clock set before going off. The design of the entire circuiting has done in different modules. This to make for easy analysis, better arrangement and for purpose of troubleshooting. The various modules in which the design has been done are as shown in fig 2.1.
THE POWER SUPPLY DESIGN SPECIFICATIONS
The aim of the power supply design is to obtain a circuit capable of producing a regulated voltage of 9Vdc and a current of about 0.30Amps from a 220ac mains supply. The block diagram of the power supply is already shown in fig 2.2.
CHAPTER FOUR
THE IMPLEMENTATION OF THE WORK
PROBLEM ENCOUNTERED
In the course of this work, there were quite a few hitches but only the major ones are hereby highlighted. The biggest problem encountered was being able to get a workable design that meets with the components available in the market. The circuits were re-designed a couple of times before a final design was obtained. Another problem encountered was in choosing and acquiring the materials for constructing the frame. A choice has to be made between wood and metal. Finally, wood was chosen as compared to metal because it is cheaper and easier to handle.
CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
CONCLUSION
In conclusion, it is pertinent to state that despite all the hitches arising from the unavailability of components and materials and technological drawbacks, the design and construction of this four way traffic light control was successfully realized. And as a matter of fact, since we are in a technological advancing world, I strongly believe that it takes nothing less than pure determination and the ability to respond to such changes to survive in the present rapidly improving standards of the world system. So being aware of all these challenges, I made special effort to examine the technological problems encountered and also made additional modification in order to enhance the services of this design.
Based on the ease of manufacture, cost, user-friendly, reliability, safety, durability etcetera, for the design of such public used product, this exquisite project has been made as simple as possible. This project also has been made as complete as required considering mostly the economic factor, and cost of materials for private and public uses which determine the response of the user towards the acquisition of such product.
During the course of this design some unforeseen problems were encountered, but were meticulously rectified. Hence, locating of faults were easy during the testing.
Finally, it is essential to say that the experience we gathered in the design and construction of this project has been rewarding.
RECOMMENDATION
In view of the theoretically and practical constraints encountered in the course of this project, we make the following general recommendations;
It is important that much research should be done on the work in other to make it synchronize with the present day advancement in technology.
A much more improved and detailed circuit should be used in the future to enable the system perform more functions.
The government should encourage the research into this field by promoting it through the installation of such system in government established offices and quarters.
REFERENCES
- Horowitz and H. Winfield “the Art of Electronics” Cambridge University press, 2ndedition 1989
- B.W. Williams “Power Electronics; Devices, Drivers, Applications and Passive Components” Macmilliam London, 2nd edition.
- M.M. Mano “Digital Logic and Computer Design”, Prentice-Hall of India
- private limited New Delhi, original US edition 1984.
- G.D. Fink and A.A. Mckenzie “Electronics Engineers Handbook”, McGraw- Hill Book Company, 1st edition, 1975.
