Design And Fabrication Of A Solar Powered Digital Street Clock

INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Time is such a fundamental concept that it is very difficult to define. To measure time is needed something that will repeat itself at regular intervals. The number of intervals counted gives a quantitative measure of the duration. The earliest references for the measurement of the time are the moon and sun. When the sun and the moon were not visible, it was impossible to know the exact time. So, clocks were developed to measure out the hours between checks with the sun and the moon.
The process of measuring time has progressively become more accurate, and the devices more localized ever since. In our modern time, the time is predominately measured by mechanical, and recently by electronic clocks. All clocks measure time, but different clocks can have status or importance.
Many centuries have been spent devising method for the determination and measurement of time. Historically, clocks and watches of all sorts lie at an important crossroads of science, technology and society. Changes in timekeeping technology have influenced the character of scientific.
A clock is an instrument to indicate, keep, and co-ordinate time. The word clock is derived ultimately (via Dutch, Northern French, and Medieval Latin) from the Celtic words clagan and clocca meaning “bell”. A silent instrument missing such a mechanism has traditionally been known as a timepiece (Baillie et al., 2015). In general usage today a “clock” refers to any device for measuring and displaying the time. Watches and other timepieces that can be carried on one’s person are often distinguished from clocks (Cambridge Advanced Learner’s Dictionary, 2009).
Clock is one of the oldest human inventions, meeting the need to consistently measure intervals of time shorter than the natural units: the day, the lunar month, and the year. Devices operating on several physical processes have been used over the millennia (Baillie et al., 2015).
There are two types of clock; analog and digital clock. Analog clocks usually indicate time using angles. Digital clocks display a numeric representation of time. Two numeric display formats are commonly used on digital clocks: 24-hour notation and 12-hour notation. Most digital clocks use electronic mechanisms and LCD, LED, or VFD displays (Baillie et al., 2015).
Analog clocks usually indicate time using angles. The most common clock face uses a fixed numbered dial or dials and moving hand or hands. It usually has a circular scale of 12 hours, which can also serve as a scale of 60 minutes, and 60 seconds if the clock has a second hand. Many other styles and designs have been used throughout the years, including dials divided into 6, 8, 10, and 24 hours. The only other widely used clock face today is the 24 hour analog dial, because of the use of 24 hour time in military organizations and timetables. The 10-hour clock was briefly popular during the French Revolution, when the metric system was applied to time measurement, and an Italian 6 hour clock was developed in the 18th century, presumably to save power (a clock or watch striking 24 times uses more power) (Baillie et al., 2015).
Digital clocks display a numeric representation of time. Two numeric display formats are commonly used on digital clocks:
• the 24-hour notation with hours ranging 00–23;
• the 12-hour notation with AM/PM indicator, with hours indicated as 12AM, followed by 1AM–11AM, followed by 12PM, followed by 1PM–11PM (a notation mostly used in domestic environments) (Baillie et al., 2015).
Most digital clocks use electronic mechanisms and LCD, LED, or VFD displays; many other display technologies are used as well (cathode ray tubes, nixie tubes, etc.). After a reset, battery change or power failure, these clocks without a backup battery or capacitor either start counting from 12:00, or stay at 12:00, often with blinking digits indicating that the time needs to be set. Some newer clocks will reset themselves based on radio or Internet time servers that are tuned to national atomic clocks. Since the advent of digital clocks in the 1960s, the use of analog clocks has declined significantly (Baillie et al., 2015). Some clocks, called ‘flip clocks’, have digital displays that work mechanically. The digits are painted on sheets of material which are mounted like the pages of a book. Once a minute, a page is turned over to reveal the next digit. These displays are usually easier to read in brightly lit conditions than LCDs or LEDs. Also, they do not go back to 12:00 after a power interruption.

1.2 PROBLEM STATEMENT
Solar powered digital street clock was built to overcome problems seen in battery powered clock such as constant replacement of dead battery and power interruption when the battery is dead. With the integration of renewable energy, digital wall clock can work all days with solar panel without interruption.

1.3 OBJECTIVE OF THE PROJECT
The main aim of this project is construct a device that will display the time in seconds, minutes and hours using LED as the displaying and solar energy as the power supply source.
The main objectives of this project are:
• To design and simulate a circuit of solar powered digital street clock using PIC16F873 as the heart of the circuit and LED as the display
• Construction of the prototype on the breadboard and testing it.
• To build a team working experience among students.
• To implement a renewable energy in a street clock

1.4 SCOPE OF THE PROJECT
This device was design using microcontroller PIC16F873 with its port pins connected directly to the four yellow LEDs via resistors and the other 12 red and 12 green LEDs were connected to the microcontroller via decoder for pins conservation. Three switches were connected to the microcontroller to set the digital clock.
1.5 ADVANTAGES OF SOLAR DIGITAL STREET CLOCK
• Even if there is power failure, this clock displays the right time using a solar inverter.
• Simplicity of the system.
• Accuracy of the system.

1.6 SCOPE AND LIMITATION OF THE STUDY
This project will extend its range till the far possible reach having a negligible delay, a setting buttons and a second display. This device counts the hour, minute and second and also uses three push buttons to set those outputs.
For the limitations,
• Use of independent LED matrix digital wall for the display that takes a huge space in the circuit and a lot of matrix code in the controller.
• Displays only hour and minute. This makes the use they give us limited on the range given.
• Not easy to maintain. When the clock gets damaged some can’t tell where the problem is easily, on the microcontroller.
• Very costly.

1.7 SIGNIFICANCE OF THE STUDY
Solar powered digital street clocks are being very useful components of our lives. Regarding this change the need of accurate and simple materials also dramatically increasing. Our proposed project uses a very simple logic devices to build.

1.8 PROJECT ORGANISATION
The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.