Design And Construction Of A Digital Stop Watch Using 555 Timers

ABSTRACT

Time, something that exists in everyone’s life, is recorded by clocks all the time in our daily life. The present widely used counting system for time is decimal base as a result of the fact that this counting base is the most convenient one for people to count using ten fingers [1]. To be more precise about the counting system of time, it is commonly known that one day is divided into 24 hours, one hour is divided into 60 minutes and one minute is divided into 60 seconds, while this particular project particularly focused on building a digital stop watch.

A stopwatch is designed to measure the amount of time elapsed from a particular time when it is activated to the time when the piece is deactivated. Stopwatch function to find out how long it takes in an activity. Usually the stopwatch is used in a variety of races: race, swimming, or even racing. The timing functions are traditionally controlled by two buttons on the case. Pressing the top button starts the timer running, and pressing the button a second time stops it, leaving the elapsed time displayed. A press of the second button then resets the stopwatch to zero. The second button is also used to record split times or lap times. When the split time button is pressed while the watch is running, the display freezes, allowing the elapsed time to that point to be read, but the watch mechanism continues running to record total elapsed time. Pressing the split button a second time allows the watch to resume display of total time.

 TABLE OF CONTENT

COVER PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION
• AIM OF THE PROJECT
• PURPOSE OF THE PROJECT
• APPLICATIONS OF THE PROJECT
• LIMITATIONS OF THE PROJECT
• OBJECTIVE OF THE PROJECT

CHAPTER TWO

LITERATURE REVIEW

2.1      HISTORICAL BACKGROUND OF DIGITAL CLOCK

2.2      THE HISTORITICAL BACKGROUND  OF THE DIGITAL CLOCK

2.3      BASIC DESIGN OF 555 TIMER

CHAPTER THREE

DESIGN METHODODLOGY

3.1      SYSTEM BLOCK DIAGRAM

3.2      SYSTEM CIRCUIT DIAGRAM

3.3      CIRCUIT COMPONENTS

3.4      CIRCUIT EXPLANATION

3.5      SYSTEM WORKING PRINCIPLES

CHAPTER FOUR

RESULTS ANALYSIS

• CONSTRUCTION PROCEDURE AND TESTING ANALYSIS
• CASING AND PACKAGING
• ASSEMBLING OF SECTIONS
• TESTING OF SYSTEM OPERATION
• INSTALLATION OF THE COMPLETED DESIGN
• COST ANALYSIS
• DESCRIPTION OF SOME MAJOR COMPONENTS USED

CHAPTER FIVE

5.1 CONCLUSION

5.2      RECOMMENDATION

5.3      REFERENCES

 CHAPTER ONE

1.0                                                        INTRODUCTION

A stopwatch is a handheld timepiece designed to measure the amount of time elapsed from a particular time when it is activated to the time when the piece is deactivated. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stopclock. In manual timing, the clock is started and stopped by a person pressing a button. In fully automatic time, both starting and stopping are triggered automatically, by sensors.

By two buttons on the case, pressing the top button starts the timer running, and pressing the button a second time stops it, leaving the elapsed time displayed. A press of the second button then resets the stopwatch to zero. The second button is also used to record split times or lap times. When the split time button is pressed while the watch is running, the display freezes then starts then freezes again, allowing the elapsed time to that point to be read, but the watch mechanism continues running to record total elapsed time. Pressing the split button a second time allows the watch to resume display of total time.

Stopwatch mode can be found in almost all cell phones nowadays. Mechanical stopwatches are powered by a mainspring, which must be periodically wound up by turning the knurled knob at the top of the watch.

Digital electronic stopwatches are available which, due to their crystal oscillator timing element, are much more accurate than mechanical timepieces. Because they contain a microchip, they often include date and time-of-day functions as well. Some may have a connector for external sensors, allowing the stopwatch to be triggered by external events, thus measuring elapsed time far more accurately than is possible by pressing the buttons with one’s finger. Stopwatches that count by 1/100 of a second are commonly mistaken as counting milliseconds, rather than centiseconds. The first digital timer used in organized sports was the Digitimer, developed by Cox Electronic Systems, Inc. of Salt Lake City Utah (1971).^[1] It utilized a Nixie-tube readout and provided a resolution of 1/1000 second. Its first use was in ski racing but was later used by the World University Games in Moscow, Russia, the U.S. NCAA, and in the Olympic trials.

The device is used when time periods must be measured precisely and with a minimum of complications. Laboratory experiments and sporting events like sprints are good examples.

The stopwatch function is also present as an additional function of many electronic devices such as wristwatches, cell phones, portable music players, and computers.

This work is on design and operation of a digital stopwatch circuit. A digital stopwatch can be a circuit displaying the actual time in minutes, hours and seconds or a circuit displaying the number of clock pulses. Here we design the second type wherein the circuit displays count from 0 to 99, representing a 60 second time interval. In other words here the circuit displays the time in seconds only. This is a simple circuit consisting of a 555 timer to produce the clock pulses and two counter ICs to carry out the counting operation.

1.2                                                   AIM OF THE PROJECT

To make a digital stop watch circuit that can count from 0 to 99 seconds, which can also be used for different applications like photo counter, person counter, countdown timer, alarm clock.

1.3                                              PURPOSE OF THE PROJECT

The main purpose of the circuit is to use it as a stop watch that can be used inorganizing athletics, quizzes etc. With small modifications, the circuit can be used for many counting purposes.

1.4                                         APPLICATIONS OF THE PROJECT

1. This circuit can be used as an indicator at quiz competitions.
2. sporting events like sprints
3. Applications include instrument (e.g., counter, DVM, etc.) display driver, computer/calculator display driver, cockpit display driver, and various clock, watch, and timer uses.

1.5                                          LIMITATIONS OF THE PROJECT

1. The circuit does not display the actual time, but rather the count of clock pulses.
2. The use of digital counter ICs produces a time delay in the whole operation, because of the propagation delay.
3. This is a theoretical circuit and may require changes.

1.6                                             OBJECTIVE OF THE PROJECT

At the end of this work, students involved will be able to:

1. Searched for electronic components used in shops,
2. Know how to generate accurate pulse.

• Design different pulse generator circuits.

1. Troubleshoot the circuits while implementing each on the bread board and testing for the accuracy of the output.
2. Understand the basic circuit used in manufacturing stopwatches, counters, digital clocks etc.