Design And Construction Of A Low-Cost Stopwatch

Electrical Electronics Engineering

The design and construction of a low-cost stopwatch involve the integration of basic electronic components to accurately measure and display elapsed time. Typically comprising a microcontroller, such as Arduino or Raspberry Pi, alongside an LCD or LED display, push-button switches, and a power source, this stopwatch can be crafted affordably. By leveraging programming languages like C or Python, one can develop the necessary code to control the timing function, user interface, and data display. Precision timing can be achieved through the utilization of crystal oscillators or real-time clocks (RTCs), while the inclusion of capacitors and resistors ensures stable operation. Furthermore, the stopwatch can be housed in a simple casing made from plastic or acrylic, enhancing durability and usability. Through cost-effective design choices and efficient construction techniques, this stopwatch provides a budget-friendly yet reliable solution for time measurement applications in various contexts.

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. The circuit uses CD4060, CD4013, CD4033, LTS543 and some discrete components. A crystal-controlled oscillator generates 1Hz pulses. A 32.768kHz miniature crystal is used for the purpose

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE PROJECT

PURPOSE OF THE PROJECT
AIM OF THE PROJECT
OBJECTIVE OF THE PROJECT
PURPOSE OF THE PROJECT
LIMITATION OF THE PROJECT
ADVANTAGES OF THE PROJECT
PROBLEM OF THE PROJECT
APPLICATION OF THE PROJECT
RESEARCH QUESTION
PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

OVERVIEW OF THE STUDY
REVIEW OF THE RELATED STUDY

CHAPTER THREE

3.0 CONSTRUCTION METHODOLOGY

3.1 BASIC OF THE SYSTEM

3.2 BLOCK DIAGRAM OF THE SYSTEM

3.3 SYSTEM OPERATION

3.4 CIRCUIT DIAGRAM

3.5 CIRCUIT DESCRIPTION

3.6 DESCRIPTION OF COMPONENTS USED

3.7 POWER SUPPLY UNIT

CHAPTER FOUR

4.0 TESTING AND RESULTS

CONSTRUCTION PROCEDURE AND TESTING
INSTALLATION OF THE COMPLET DESIGN
ASSEMBLING OF SECTIONS
TESTING OF SYSTEM OPERATION
COST ANALYSIS

CHAPTER FIVE

CONCLUSION
RECOMMENDATION
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 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 construction of a simple stopwatch circuit. The circuit uses CD4060, CD4013, CD4033, LTS543 and some discrete components. A crystal-controlled oscillator generates 1Hz pulses. A 32.768kHz miniature crystal is used for the purpose.

1.2 AIM OF THE PROJECT

To make a simple stopwatch 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

This circuit can be used as an indicator at quiz competitions.
sporting events like sprints
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

The circuit does not display the actual time, but rather the count of clock pulses.
The use of digital counter ICs produces a time delay in the whole operation, because of the propagation delay.
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:

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

Design different pulse generator circuits.

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

1.7 SIGNIFICANCE OF THE PROJECT

The advantages of using a stopwatch is that it gives you a general measurement of how much time it take an object to do something start to finish.

1.8 PROBLEM OF THE PROJECT

The only problem of using a stopwatch is that it is not extremely precise or accurate.

1.9 PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to this study. In this chapter, the background, significance, scope, objective, limitation and problem, advantages of this work was discussed.

Chapter two is on literature review of the study. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE PROJECT

PURPOSE OF THE PROJECT
AIM OF THE PROJECT
OBJECTIVE OF THE PROJECT
PURPOSE OF THE PROJECT
LIMITATION OF THE PROJECT
ADVANTAGES OF THE PROJECT
PROBLEM OF THE PROJECT
APPLICATION OF THE PROJECT
RESEARCH QUESTION
PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

OVERVIEW OF THE STUDY
REVIEW OF THE RELATED STUDY

CHAPTER THREE

3.0 CONSTRUCTION METHODOLOGY

3.1 BASIC OF THE SYSTEM

3.2 BLOCK DIAGRAM OF THE SYSTEM

3.3 SYSTEM OPERATION

3.4 CIRCUIT DIAGRAM

3.5 CIRCUIT DESCRIPTION

3.6 DESCRIPTION OF COMPONENTS USED

3.7 POWER SUPPLY UNIT

CHAPTER FOUR

4.0 TESTING AND RESULTS

CONSTRUCTION PROCEDURE AND TESTING
INSTALLATION OF THE COMPLET DESIGN
ASSEMBLING OF SECTIONS
TESTING OF SYSTEM OPERATION
COST ANALYSIS

CHAPTER FIVE

CONCLUSION
RECOMMENDATION
REFERENCES

Here is a simple circuit of a low-cost stopwatch that can count up to 99 seconds. The circuit uses CD4060, CD4013, CD4033, LTS543 and some discrete components. A crystal-controlled oscillator generates 1Hz pulses. A 32.768kHz miniature crystal is used for the purpose.

A low-cost stopwatch circuit

IC CD4060 (IC1) contains a 14-bit divider stage and oscillator section. The 2Hz output of IC1 at its pin 3 is fed to flip-flop IC CD4013 (IC2). IC2 converts 2 Hz into 1 Hz. The output of IC2 at pin 1 is fed to IC CD4033 (IC3) through switch S1. Carry-out pin 5 of IC3 is connected to pin 1 of another CD4033 (IC4) for further counting. IC3 and IC4 drive common-cathode display DIS1 and DIS2 to show the time (maximum 99 seconds). Switch S1 is used to start and stop the watch. You can reset the counter to zero by pressing reset switch S2.

Low-cost stopwatch circuit

For proper operation, first, connect a 9V power supply to the circuit, then reset the display by momentarily pressing switch S2. The display shows ‘00.’ Now to start counting, flip switch S1 to ‘on’ position. At the time of completion of an event, flip switch S1 to ‘off’ position. Time shown on the display is the time for the event.

Construction & testing

Assemble the circuit on a general-purpose PCB and enclose in a suitable case. Mount 7-segment, common-cathode displays DIS1 and DIS2, and switches S1 and S2, on the front panel of the cabinet. As the circuit employs CMOS ICs, the supply voltage may vary from 5V to 15V. 9V supply is recommended.