Design And Construction Of A Quartz Clock

ABSTRACT

A quartz clock is an electronic clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks are at least an order of magnitude more accurate than mechanical clocks. Generally, some form of digital logic counts the cycles of this signal and provides a numeric time display, usually in units of hours, minutes, and seconds.

TABLE OF CONTENTS

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

1.0      INTRODUCTION

1.1      BACKGROUND OF THE PROJECT
1.2      AIM OF THE PROJECT
1.3      OBJECTIVE OF THE PROJECT
1.4      SIGNIFICANCE OF THE PROJECT
1.5      PURPOSE OF THE PROJECT
1.6      APPLICATION OF THE PROJECT
1.7      ADVANTAGES OF THE PROJECT
1.8      PROBLEM/LIMITATION OF THE PROJECT
1.9      PROJECT ORGANISATION

CHAPTER TWO

2.0     LITERATURE REVIEW

2.1      REVIEW OF RELATED STUDIES

2.2      REVIEW OF RELATED TERMS

CHAPTER THREE

3.0     CONSTRUCTION METHODOLOGY

3.1      SYSTEM CIRCUIT DIAGRAM

3.2     SYSTEM OPERATION

3.3      CIRCUIT DESCRIPTION

3.4      SYSTEM CIRCUIT DIAGRAM

3.5      CIRCUIT OPERATION

3.6   IMPORTANCE AND FUNCTION OF THE MAJOR COMPONENTS USED IN THIS CIRCUIT

3.7      POWER SUPPLY UNIT

CHAPTER FOUR

RESULT ANALYSIS

4.0      CONSTRUCTION PROCEDURE AND TESTING

4.1      CASING AND PACKAGING

4.2      ASSEMBLING OF SECTIONS

4.3      TESTING

4.4.1 PRE-IMPLEMENTATION TESTING

4.4.2  POST-IMPLEMENTATION TESTING

4.5      RESULT

4.6      COST ANALYSIS

CHAPTER FIVE

5.0      CONCLUSION

5.1      RECOMMENDATION

5.2      REFERENCES

CHAPTER ONE

• INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

The world’s first quartz clock was built in 1927 by Warren Marrison and J. W. Horton at Bell Telephone Laboratories. The world’s first quartz watch, however, was unveiled by Seiko as the Astron in December 1969.^[1][2] Since the 1980s, when the advent of solid-state digital electronics allowed them to be made compact and inexpensive, quartz timekeepers have become the world’s most widely used timekeeping technology, used in most clocks and watches, as well as computers and other appliances that keep time.

First quartz wristwatch movement, used in the Seiko Astron, Caliber 35A, Nr. 00234, Seiko, Japan, 1969 (German Clock Museum, Inv. 2010-006)

Chemically, quartz is a specific form of a compound called silicon dioxide. Many materials can be formed into plates that will resonate. However, quartz is also a piezoelectric material: that is, when a quartz crystal is subject to mechanical stress, such as bending, it accumulates electrical charge across some planes. In a reverse effect, if charges are placed across the crystal plane, quartz crystals will bend. Since quartz can be directly driven (to flex) by an electric signal, no additional transducer is required to use it in a resonator. Similar crystals are used in low-end phonograph cartridges: The movement of the stylus (needle) flexes a quartz crystal, which produces a small voltage, which is amplified and played through speakers. Quartz microphones are still available, though not common.

In the early 20^th century, radio engineers sought a precise, stable source of radio frequencies and started at first with steel resonators. However, when Walter Guyton Cady found that quartz can resonate with less equipment and better temperature stability, steel resonators disappeared within a few years. Later, scientists at NIST (then the U.S. National Bureau of Standards) discovered that a crystal oscillator could be more accurate than a pendulum clock.

The electronic circuit is an oscillator, an amplifier whose output passes through the quartz resonator. The resonator acts as an electronic filter, eliminating all but the single frequency of interest. The output of the resonator feeds back to the input of the amplifier, and the resonator assures that the oscillator “howls” with the exact frequency of interest. When the circuit starts up, even a single shot can cascade to bringing the oscillator to the desired frequency. If the amplifier is too perfect, the oscillator will not start.

The frequency at which the crystal oscillates depends on its shape, size, and the crystal plane on which the quartz is cut. The positions at which electrodes are placed can slightly change the tuning as well. If the crystal is accurately shaped and positioned, it will oscillate at a desired frequency. In nearly all quartz watches, the frequency is 32768 Hz,^[3] and the crystal is cut in a small tuning fork shape on a particular crystal plane. This frequency is a power of two (32768 = 2¹⁵), just high enough so most people cannot hear it, yet low enough to permit inexpensive counters to derive a 1-second pulse. A 15-bit binary digital counter driven by the frequency will overflow once per second, creating a digital pulse once per second. The pulse-per-second output can be used to drive many kinds of clocks.

Although quartz has a very low coefficient of thermal expansion, temperature changes are the major cause of frequency variation in crystal oscillators. The most obvious way of reducing the effect of temperature on oscillation rate is to keep the crystal at a constant temperature. For laboratory-grade oscillators an oven-controlled crystal oscillator is used, in which the crystal is kept in a very small oven that is held at a constant temperature. This method is, however, impractical for consumer quartz clock and wrist-watch movements.

1.2                                                   AIM OF THE PROJECT

The main aim of this project is construct a device that will be used to check time.

1.3                             OBJECTIVE OF THE PROJECT

At the end of this work, Students will

• identify the placement of numerals and hands on an analog clock;
• experience in a physical way the values of the intervals of minutes and hours;
• learn the meanings of expressions such as half past, quarter past, and quarter of (to, till).

1.4                            SIGNIFICANCE OF THE PROJET

Quartz has advantages in that its size does not change much as temperature fluctuates. Fused quartz is often used for laboratory equipment that must not change shape along with the temperature. A quartz plate’s resonance frequency, based on its size, will not significantly rise or fall. Similarly, since its resonator does not change shape, a quartz clock will remain relatively accurate as the temperature changes.

Quartz clocks are battery powered and, because they use so little electricity, the battery can often last several years before you need to replace it. They are also much more accurate than pendulum clocks. Quartz watches work in a very different way to pendulum clocks and ordinary watches. They still have gears inside them to count the seconds, minutes, and hours and sweep the hands around the clock face. But the gears are regulated by a tiny crystal of quartz instead of a swinging pendulum or a moving balance wheel.

1.5                               PURPOSE OF THE PROJECT

The main purpose of this work is to have an instrument used to measure, keep, and indicate time.

1.6                  LIMITATION/PROBLEM OF THE PROJECT

Quartz clock can easily affected by environmental temperature swings, since a correctly designed watch case forms an expedient crystal oven that uses the stable temperature of the human body to keep the crystal in its most accurate temperature range. Quartz watch manufacturers use a simplified version of the oven-controlled crystal oscillator method by recommending that their watches be worn regularly to ensure best performance. Regular wearing of a quartz watch significantly reduces the magnitude of environmental temperature swings.