ABSTRACT

While time is that with which events are distinguished with reference to present, before and after, a clock basically is a term that is used to describe a freestanding device that measures and records time, which it displays by a pointer on a dial or by a digital readout on the display unit. The importance of time cannot be acknowledged without a comprehensive measure of its value for events and for this reasons the measuring instrument for time is of a very great importance to mankind. The importance of the digital clock is the main reason for the implementation of the project. The digital clock implemented in the project is designed to use oscillations from power supply line. This is achieved by utilizing the oscillation from the ac power supply system where the 50Hz frequency supplied from a power line supply. The use of the frequency is achieved by the frequency dividers provided in the project. The 50 Hz is first divided by a divide by ten logic circuit in the project this divide by ten circuits is configured from a decade counter in the project. The 5Hz output from this circuit is then subjected to another divide by five units which divide the frequency to a value of 1Hz which is optimum for the 60 seconds repetitive clocks of a digital clock. The logic behind these divisions is to create a one second oscillations from the power supply line. The project is implemented using logic gates that provide the required operation of the project. The display of the project is the seven segment display. That displays the time in seconds, minutes and seconds on the display. The digital clock designed in this project finds applications in such places as hospitals, school workshops and in homes. It can also be used for outdoor applications by replacement of the seven segment display with larger ones.

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CHAPTER ONE

1.0 INTRODUCTION

A clock basically a freestanding device that measures and records time, which it displays

by a pointer on a dial or by a digital readout. 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. 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. The 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

different physical processes have been used over the millennia, culminating in the clocks

of today.

The importance of time cannot be acknowledged without a comprehensive measure of its

value for its event and for this reasons the measuring instrument for time is of a very

great importance to mankind. There are several types of clocks that exist today all of

whose aim is to provide a digital read out of time in a given society. These types range

from the analog to the digital types. The analog types use a deflection technique to

indicate the time on a given scale. While the digital type is a clock or watch in which the

hours, minutes, and sometimes seconds are indicated by digits, rather than by hands on a

dial compare analogue clock. We see digital time displays in various applications

worldwide, in our homes, in airports, along the highways and many other places. But this

has not always been the case. For years, an approximate analog display was good enough.

But as our lives became more precise, so did our dependence on accurate time. And

science, which is always struggling to keep abreast of demands, complied by developing

the digital clock. But don't confuse digital clocks with digital displays. A digital watch, of

course, is technically just a small digital clock. But its history is a bit different. The first

watch called "digital" was actually an electric watch developed by Hamilton in 1957. In

1960, Bulova came out with the Accutron, for a breakthrough in accuracy. The Swiss

2

developed the quartz crystal movement in 1967. But all these small clocks had analog

displays. The first digital display came out in 1972 in the Hamilton Pulsar P1, using light

emitting diodes (LED,s). A few months later, Gruen came out with the Teletime, using a

liquid crystal (LCD) display. Today, most digital watches use a quartz movement with an

LCD display. In many cases the circuitry that runs them are indeed digital. So the term

digital clock in common usage could be confusing, once we learn a more scientific use of

the word "clock." The trend to use digital displays began around 1972, for clocks,

watches, calculators and various types of meters.

Traditional punch clocks were originally invented in the late 1800s and went into

common use just after the turn of the century. The difference between early models and

later forms basically boiled down to size and automation. The early clocks were large and

complicated and required a worker to manually care for the clock mechanism. Later

clocks were smaller, with self-winding or electronic clocks.

The design of the digital clock using the power line is based on the heart of the clock

where there is a piece that can generate an accurate 60-hertz (Hz, oscillations per second)

signal. The signal can be extracted from the 60-Hz oscillations in a normal power line.

Many clocks that get their power from a wall socket use this technique because it is cheap

and easy. The 50-Hz signal on the power line is reasonably accurate for this purpose.

The 60-Hz signal is divided down using a counter. When building the project work, a

typical TTL part to use is a 7490 decade counter. This part can be configured to divide by

any number between 2 and 10, and generates a binary number as output. So you take your

60-Hz time base, divide it by 10, divide it by 6 and now you have a 1-Hz (1 oscillation

per second) signal. This 1-Hz signal is perfect for driving the "second hand" portion of

the display. So far, the clock looks like this in a block diagram:

Figure 1.1: Generation of 1 Hz Signal From Power Line

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To actually see the seconds, then the output of the counters needs to drive a display. The

two counters produce binary numbers. The divide-by-10 counter is producing a 0-1-2-3-

4-5-6-7-8-9 sequence on its outputs, while the divide-by-6 counter is producing a 0-1-2-

3-4-5 sequence on its outputs. We want to display these binary numbers on something

called a 7-segment display. A 7-segment display has seven bars on it, and by turning on

different bars you can display different numbers:

To convert a binary number between 0 and 9 to the appropriate signals to drive a 7-

segment display, you use a (appropriately named) "binary number to 7-segment display

converter." This chip looks at the binary number coming in and turns on the appropriate

bars in the 7-segment LED to display that number. If we are displaying the seconds, then

the second’s part of the clock looks like this:

Figure 1.2: The Seven Segment Display of Seconds

The output from this stage oscillates at a frequency of one-cycle-per-minute. You can

imagine that the minute’s section of the clock looks exactly the same. Finally, the hour’s

section looks almost the same except that the divide-by-6 counter is replaced by a divide-

by-2 counter.

1.1 BACKGROUND OF THE STUDY

Science has known for a long time that atoms have a resonance, which means that their

electrons will circle their nuclei an exact number of times per second. In 1949, the

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National Institute of Science and Technology (NIST) developed the first atomic clock,

based on the number of revolutions in an atom of ammonia. But even though it was not

very accurate, it was digital because it was based on a number of events rather than

fractions of time of the Earth's rotation. Researchers soon replaced ammonia with cesium

to find ways to be more accurate. The first watch/clock called "digital" was actually an

electric watch developed by Hamilton in 1957. In 1960, Bulova came out with the

Accutron, for a breakthrough in accuracy. The Swiss developed the quartz crystal

movement in 1967. But all these small clocks had analog displays. The first digital

display came out in 1972 in the Hamilton Pulsar P1, using light emitting diodes (LED,s).

A few months later, Gruen came out with the Teletime, using a liquid crystal (LCD)

display. Today, most digital watches use a quartz movement with an LCD display. Since

these discoveries a number of digital clocks have being made by different researchers.

The digital clock that is implemented in this project is not much way different from the

contemporary types and only differs in the way by which there oscillations are generated.

1.2 AIM AND OBJECTIVES

The main aim this project is to design and implement a digital clock system with which

the time can be reliable read with precision by the use of logic integrated circuits.

The design and implementation of this project is carried out with the following

objectives.

• To investigate the problems associated the various forms of clocks that exists and also

examine the various forms of digital clocks available. Investigating there advantages,

disadvantages and utilizing this in the expected design.

• To implement a very reliable system of digital clock method that provides a more

efficient time measurement than the systems reviewed.

• To investigate the various possible means of implementing a system of time measurement

and clocks that exists and also reviewing the various methods in which the digital clock

can be implemented and utilize these in the design of the system.

1.3 SCOPE OF THE STUDY

The digital clock in this project covers a wide range of indoor applications ranging from

use in domestic buildings to the use in industrial and commercial places for use to display

the time of the day. It is required to display in digital form by using the seven segment

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display that shows continues running of the time giving the seconds reading, minutes

reading and the hour reading.

1.4 SIGNIFICANCE

We see digital time displays in various applications worldwide, in our homes, in airports,

along the highways and many other places. But this has not always been the case. For

years, an approximate analog display was good enough. But as our lives became more

precise, so did our dependence on accurate time. And science, which is always struggling

to keep abreast of demands, complied by developing the digital clock. The clock is one of

the most important devices of all civilization. It is simply a gadget that we use to tell the

exact time of day. The digital clock is used in many activities in the world such as sports

of all kinds, industrial applications, schools and many other areas of application.

1.5 STATEMENT OF PROBLEMS

The invention of the digital clock, there have existed many different forms of designing

the digital clocks. These ranges from types of displays, types of oscillators, the counter

systems and the operation principles of which all are aimed at providing an efficient less

cost and more reliable clocks. Of these systems, the choice for the use of the logic type

design is based on theirs simplicity, low cost of implementation and efficiency.

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2.0 LITERATURE REVIEW

2.1 Introduction

The clocks we have in our society today all have a common ancestor. Their common

ancestor is the sun dial. It would cast the sun's shadow around its fixed centre to show us

the time. The sun dial had a huge disadvantage that today's clocks do not have. It only

worked during the day. Since the invention of the sun dial, there have existed a number of

types of clocks which lead to the evolution of the digital clock.

2.2 An Overview of the History of Digital Clock

Science has known for a long time that atoms have a resonance, which means that their

electrons will circle their nuclei an exact number of times per second. In 1949, the

National Institute of Science and Technology (NIST) developed the first atomic clock,

based on the number of revolutions in an atom of ammonia. But even though it was not

very accurate, it was digital because it was based on a number of events rather than

fractions of time of the Earth's rotation. Researchers soon replaced ammonia with cesium

to find ways to be more accurate. In 1955 the National Physical Laboratory in England,

along with the U.S. Naval Observatory built the first cesium atomic clock, in the form of

a frequency standard measure, relative to astronomical time based on the motion of stars.

In 1960, NIST's development of cesium standards reached a point refined enough to

incorporate cesium into their official time-keeping system, thus making the national

standard for time digital. Other laboratories began accepting cesium as the new time-

keeping standard. In 1967, the second became formally defined as exactly 9,192,631,770

cycles of a cesium atom's resonant frequency, replacing the old definition of the second,

which was 1/86,400th of a day. Thus, the definition of a second became digital instead of

analog. By January of 2002, NIST was able to measure a second to the accuracy of 30

billionths of a second per year, in their eighth series of cesium clocks using the "fountain"

principle. Today, some atomic clocks use hydrogen and rubidium vapor because of more

compact size, lower cost and less power consumption.

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Digital clock displays have used LEDs, LCDs or printed flaps or wheels moving to show

hours and minutes. Analog displays use hands. Many microwave ovens, clock radios,

regular ovens, kitchen timers, alarm clocks and many other appliances use digital

displays for time and other information. In many cases the circuitry that runs them are

indeed digital. So the term digital clock in common usage could be confusing, once we

learn a more scientific use of the word "clock." The trend to use digital displays began

around 1972, for clocks, watches, calculators and various types of meters. A digital

watch, of course, is technically just a small digital clock. But its history is a bit different.

The first watch called "digital" was actually an electric watch developed by Hamilton in

1957. In 1960, Bulova came out with the Accutron, for a breakthrough in accuracy. The

Swiss developed the quartz crystal movement in 1967. But all these small clocks had

analog displays. The first digital display came out in 1972 in the Hamilton Pulsar P1,

using light emitting diodes (LED,s). A few months later, Gruen came out with the

Teletime, using a liquid crystal (LCD) display. Today, most digital watches use a quartz

movement with an LCD display.

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3.0 DESIGN ANALYSIS

3.1 METHODOLOGY

The method used for the implementation of the project is by arrangement of the project

into subunits which are put together to make pun the entire system. The method used for

the implementation of the project is by the use of empirical observation on the case study

in the project which is the implementation of a digital clock using the power line

3.1 Requirements elicitation

Since the system is completely new, the requirements will be based on the perception of

the fact that a digital clock is required to be implemented by the use of the ac power line,

An understanding of the operation of the digital clock was a great requirement of the

project design and for this reason, the project was designed by sectioning the various

units.

3.1.1 Data collection methods

The library and the internet will be some of the sources of relevant literature about digital

clocks and their methods of implementation. These will be used to obtain some of the

requirements of the system. Relevant textbooks contained in the polytechnic library and

the different data from the web pages, journals, research papers and newspapers obtained

from the internet will be considered.

3.1.2 Data Interpretation and Analysis

This will aim at extracting requirements from all the collected data for designing the

system. The data collected shall be analyzed basing on the objectives of the study. This

will be done qualitatively by giving meaning to findings to be able to make effective

recommendations. Data will be cross checked for consistency basing on the concepts of

the literature review and interpreted to provide requirements for designing a power line

based digital clock. The strength of the existing systems will be incorporated into the new

design whereas their weaknesses will be clearly studied to be solved.

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3.2 Review of the System Requirements

The requirement of this project is to utilize the supply line frequency to design the

required oscillations for the implementation of a digital clock. This is because the power

line frequency is mostly always constant and the use of power line frequency for digital

cloak oscillations limits the probability of errors in the clock.

3.3 System Design

The project is designed by subdividing the entire work into subunits which aids the

proper implementation of the project. The main advantage of this approach is that it

facilitates troubleshooting during the proper implementation of the project. The design of

the project consists of the following sections

The power supply unit

The power line frequency source unit

The frequency division unit

The seven segment driver unit

The seven segment display unit

3.4 Power Supply Unit

In alternating current the electron flow is alternate, i.e. the electron flow increases to

maximum in one direction, decreases back to zero. It then increases in the other direction

and then decreases to zero again. Direct current flows in one direction only. Rectifier

converts alternating current to flow in one direction only. When the anode of the diode is

positive with respect to its cathode, it is forward biased, allowing current to flow. But

when its anode is negative with respect to the cathode, it is reverse biased and does not

allow current to flow. This unidirectional property of the diode is useful for rectification.

A single diode arranged back-to-back might allow the electrons to flow during positive

half cycles only and suppress the negative half cycles. Double diodes arranged back-to-10

back might act as full wave rectifiers as they may allow the electron flow during both

positive and negative half cycles. Four diodes can be arranged to make a full wave bridge

rectifier. Different types of filter circuits are used to smooth out the pulsations in

amplitude of the output voltage from a rectifier. The property of capacitor to oppose any

change in the voltage applied across them by storing energy in the electric field of the

capacitor and of inductors to oppose any change in the current flowing through them by

storing energy in the magnetic field of coil may be utilized. To remove pulsation of the

direct current obtained from the rectifier, different types of combination of capacitor,

inductors and resistors may be also be used to increase to action of filtering.

3.4.1 Use of diodes in rectifiers:

Electric energy is available in homes and industries in Nigeria, in the form of alternating

voltage. The supply has a voltage of 220v (rms) at a frequency of 50 Hz. For the

operation of most of the devices in electronic equipment, a dc voltage is needed. For the

operation of the project a power supply unit is required. Usually, this supply can be

provided by dry cells. But sometime we use a battery eliminator in place of dry cells. The

battery eliminator converts the ac voltage into dc voltage and thus eliminates the need for

dry cells. Nowadays, almost all-electronic equipment includes a circuit that converts ac

voltage of mains supply into dc voltage. This part of the equipment is called power

supply. In general, at the input of the power supply, there is a power transformer. It is

followed by a diode circuit called rectifier. The output of the rectifier goes to a smoothing

filter, and then to a voltage regulator circuit. The rectifier circuit is the heart of a power

supply.

3.4.2 Rectification

Rectification is a process of rendering an alternating current or voltage into a

unidirectional one. The component used for rectification is called ‘rectifier’. A rectifier

permits current to flow only during the positive half cycles of the applied ac voltage by

eliminating the negative half cycles or alternations of the applied ac voltage. Thus

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pulsating dc is obtained. To obtain smooth dc power, additional filter circuits are

required.

A diode can be used as rectifier. There are various types of diodes. But, semiconductor

diodes are very popularly used as rectifiers. A semiconductor diode is a solid-state device

consisting of two elements is being an electron emitter or cathode, the other an electron

collector or anode. Since electrons in a semiconductor diode can flow in one direction

only-from emitter to collector- the diode provides the unilateral conduction necessary for

rectification. Out of the semiconductor diodes, copper oxide and selenium rectifier are

also commonly used.

3.4.4 Full wave rectifier

It is possible to rectify both alternations of the input voltage by using two diodes in the

circuit arrangement. Assume 6.3 v rms (18 v p-p) is applied to the circuit. Assume further

that two equal-valued series-connected resistors R are placed in parallel with the ac

source. The 18 v p-p appears across the two resistors connected between points ac and cb,

and point c is the electrical midpoint between a and b. Hence 9 v p-p appears across each

resistor. At any moment during a cycle of vin, if point a is positive relative to c, point b is

negative relative to c. When a is negative to c, point b is positive relative to c. The

effective voltage in proper time phase which each diode "sees" is in fig. The voltage

applied to the anode of each diode is equal but opposite in polarity at any given instant.

When a is positive relative to c, the anode of d1 is positive with respect to its cathode.

Hence d1 will conduct but d2 will not. During the second alternation, b is positive

relative to c. The anode of d2 is therefore positive with respect to its cathode, and d2

conducts while d1 is cut off. There is conduction then by either d1 or d2 during the entire

input-voltage cycle. Since the two diodes have a common-cathode load resistor rl, the

output voltage across rl will result from the alternate conduction of d1 and d2. The output

waveform vout across rl, therefore has no gaps as in the case of the half-wave rectifier.

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The output of a full-wave rectifier is also pulsating direct current. In the diagram, the two

equal resistors r across the input voltage are necessary to provide a voltage midpoint c for

circuit connection and zero reference. Note that the load resistor rl is connected from the

cathodes to this center reference point c. An interesting fact about the output waveform

vout is that its peak amplitude is not 9 v as in the case of the half-wave rectifier using the

same power source, but is less than 4½ v. The reason, of course, is that the peak positive

voltage of a relative to c is 4½ v, not 9v, and part of the 4½ v is lost across r.

Though the full wave rectifier fills in the conduction gaps, it delivers less than half the

peak output voltage that results from half-wave rectification.

3.4.5 Bridge rectifier

A more widely used full-wave rectifier circuit is the bridge rectifier. It requires four

diodes instead of two, but avoids the need for a centre-tapped transformer. During the

positive half-cycle of the secondary voltage, diodes d2 and d4 are conducting and diodes

d1 and d3 are non-conducting. Therefore, current flows through the secondary winding,

diode d2, load resistor rl and diode d4. During negative half-cycles of the secondary

voltage, diodes d1 and d3 conduct, and the diodes d2 and d4 do not conduct. The current

therefore flows through the secondary winding, diode d1, load resistor rl and diode d3. In

both cases, the current passes through the load resistor in the same direction. Therefore, a

fluctuating, unidirectional voltage is developed across the load.

3.4.6 Filtration

The rectifier circuits we have discussed above deliver an output voltage that always has

the same polarity: but however, this output is not suitable as dc power supply for solid-

state circuits. This is due to the pulsation or ripples of the output voltage. This should be

removed out before the output voltage can be supplied to any circuit. This smoothing is

done by incorporating filter networks. The filter network consists of inductors and

capacitors. The inductors or choke coils are generally connected in series with the

rectifier output and the load. The inductors oppose any change in the magnitude of a

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current flowing through them by storing up energy in a magnetic field. An inductor offers

very low resistance for dc whereas; it offers very high resistance to ac. Thus, a series

connected choke coil in a rectifier circuit helps to reduce the pulsations or ripples to a

great extent in the output voltage. The fitter capacitors are usually connected in parallel

with the rectifier output and the load. As, ac can pass through a capacitor but dc cannot,

the ripples are thus limited and the output becomes smoothed. When the voltage across

its plates tends to rise, it stores up energy back into voltage and current. Thus, the

fluctuations in the output voltage are reduced considerable. Filter network circuits may be

of two types in general:

3.4.7 Choke input filter

If a choke coil or an inductor is used as the ‘first- components’ in the filter network, the

filter is called ‘choke input filter’. The d.c. along with ac pulsation from the rectifier

circuit at first passes through the choke. It opposes the ac pulsations but allows the dc to

pass through it freely. Thus ac pulsations are largely reduced. The further ripples are by

passed through the parallel capacitor c. But, however, a little nipple remains unaffected,

which are considered negligible. This little ripple may be reduced by incorporating a

series a choke input filters.

3.4.8 Capacitor input filter

If a capacitor is placed before the inductors of a choke-input filter network, the filter is

called capacitor input filter. The d.c. along with ac ripples from the rectifier circuit starts

charging the capacitor c. To about peak value. The ac ripples are then diminished

slightly. Now the capacitor c, discharges through the inductor or choke coil, which

opposes the ac ripples, except the dc. The capacitor c by passes the further ac ripples. A

small ripple is still present in the output of dc, which may be reduced by adding

additional filter network in series.

The power supply unit is built around a step-down transformer which steps down the

supply voltage of 220v to a 30v output. This stepped down output voltage supplied to a

bridge rectifier for rectification of the voltage from an ac into a dc voltage. The rectified 14

voltage is then passed to the capacitor to filter off all the unwanted ripples in the output

of the rectifier. The smooth dc – output voltage is now passed through a voltage regulator

that regulates the voltage to a supply output required for the operation of the system.

In calculating the required voltage of the capacitor required for the filter, we apply the

following formulae.

C = _______________(1)

Where F = frequency

r = ripple factor

RL = Vmax / Irated (Load Resistance)

RL = ________(2)

RL= = 84Ω

Ripple factor r is given by

r =

But Vmax = Vrms

Hence

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r =

=

r = 0.4142 x 100%

41.42%

C =

C =

= 4.149 x F

Since the transformer used for the power supply unit takes 220v input and gives an output

voltage of 30v, the value of the transformation ratio can be calculated as follows.

N1/No = E1/Eo = φ

Where

φ = Transformation ratio

N1 = Number of secondary turns

No = Number of Primary turns

E0 = Primary voltage

E1 = Secondary voltage

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φ = 220 = 7 . 33

30v.

∴ Therefore, the transformation ratio is equal to 7:33

3.5 The Operation of the Project

The design of the digital clock using the power line is based on the heart of the clock

where there is a piece that can generate an accurate 60-hertz (Hz, oscillations per second)

signal. The signal can be extracted from the 60-Hz oscillations in a normal power line.

Many clocks that get their power from a wall socket use this technique because it is cheap

and easy. The 50-Hz signal on the power line is reasonably accurate for this purpose.

The 60-Hz signal is divided down using a counter. When building the project work, a

typical TTL part to use is a 7490 decade counter. This part can be configured to divide by

any number between 2 and 10, and generates a binary number as output. So you take your

60-Hz time base, divide it by 10, divide it by 6 and now you have a 1-Hz (1 oscillation

per second) signal. This 1-Hz signal is perfect for driving the "second hand" portion of

the display. So far, the clock looks like this in a block diagram:

Figure 3.1: Generation of 1 Hz Signal From Power Line

To actually see the seconds, then the output of the counters needs to drive a display. The

two counters produce binary numbers. The divide-by-10 counter is producing a 0-1-2-3-

4-5-6-7-8-9 sequence on its outputs, while the divide-by-6 counter is producing a 0-1-2-

3-4-5 sequence on its outputs. We want to display these binary numbers on something

called a 7-segment display. A 7-segment display has seven bars on it, and by turning on

different bars you can display different numbers:

17

To convert a binary number between 0 and 9 to the appropriate signals to drive a 7-

segment display, you use a (appropriately named) "binary number to 7-segment display

converter." This chip looks at the binary number coming in and turns on the appropriate

bars in the 7-segment LED to display that number. If we are displaying the seconds, then

the second’s part of the clock looks like this:

Figure 3.2: The Seven Segment Display of Seconds

The output from this stage oscillates at a frequency of one-cycle-per-minute. You can

imagine that the minute’s section of the clock looks exactly the same. Finally, the hour’s

section looks almost the same except that the divide-by-6 counter is replaced by a divide-

by-2 counter.

3.6 0-5 Counter

Here, a 0-5 acts as a digital output for ten’s digit of minute. The basic idea of implementation of 0-5 counter is based on JK- flip flop to ripple the digits. Digit starts from 00 when it reaches to 5 and then returns to 00. The truth table of 0-5 counter is shown below.

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Table 3.1: The Table Of 0 To 5 Counters

The schematic and layout of 0-5 counter are shown in Figure, in this design; we used 3 JK flip flops, Inverters, and NAND gates.

3.7 0-9 counter

0-9 counter is a larger version of 0-5 counter. Here, 0-9 counter acts as a digital output for units of minute. The basic idea of implementation of 0-9 counter is also based on JK flipflop to ripple the digits. Digits start from 00, when they reach 9 in decimal and then return to 00. The truth table of 0-9 counter is shown below.

Table 3.2: table of 0 to 9 counter

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3.7 Seven Segment Decoder

Here, a six 7 segment Decoder is used for output binary digits of Second Minutes and Hours in LEDs display. Normally, LEDs Display has the function as follows, and we usually use the previous 10 output from 0 to 9.

Table 3.3: The Table of the Seven Segment Display

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To implement this function, we generate the truth table for a four Seven Segment decoder as above and get its corresponding seven segment output and annotate them in decimal.

3.8 The Project Circuit Diagram

The circuit diagram for the implementation of the project can be illustrated by the

following figure

Figure 3.3: The Proposed Circuit Diagram For the Project

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4.0 SUMMARY AND CONCLUSION

4.1 Summary

The digital clock is a type of clock that displays the time digitally, as opposed to an

analog clock, where the time is displayed by hands. In this project, the digital clock is

built with 12 hour count time. The clock runs from 12:00 to 11:59 and then back to12:00

this project pre examines the operational principles of the basic digital clock. The project

that is presented in this thesis is a digital clock that is implemented by the use of the

power line frequency to generate the oscillation

The thesis presented in this paper gives a comprehensive analysis of the design and

implementation of a digital electronic clock using the power line oscillations. The main

aim and objective of the implementation of the project is to design a digital clock with

which the display of time in any place can be achieved. The thesis is divided into four

major chapters. The abstract of the project gives a comprehensive summary of the

project. It highlights the problems the objectives and the operating principles of the

project in summary. The chapter one of the project introduces the concept of electronic

digital clocks, the existing types and the background of digital clock; it highlights the

problems, the aims and objectives of the research, the background and the scope of the

project. The chapter one of the project gives the reader an insight of what the research is

about. The chapter two of the project presents the literature review of the project. It pre-

examines the historical background of the project and also reviews previous works done

relating to the same aims and objectives, reviewing their success and failures as well as

the modifications to be input on the works to achieve a more reliable system. The chapter

three of the project presents the design analysis of the project it reviews the various

sections of the project there design procedures and the implementation process. It also

presents the necessary calculations carried out in the course of the design. It also presents

the block diagram, the circuit diagram and the flow chart of the project. The chapter four

of this thesis presents the summary and conclusion of the entire work.

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4.2 Conclusions

Conclusively, at the end of a comprehensive research on the guiding principles of many

types of digital clocks that exists, i hereby conclude that the project research has provided

a platform for the application principles of electrical engineering and the operational

principles of the digital clock. And as a result, I assure that the project would work n an

accordance with the operational principles reviewed in the analysis of the project.

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