ELECTRONIC CLOCK


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Introduction

The clock is one of the most important discoveries in the history of man and civilization.

The division of time into slots with different sizes and units is fundamental to the operation of society as well as individual.

Hesiod, writing in the 8th century BC., used celestial bodies to indicate agricultural cycles. Later Greek scientists, such as Archimedes, developed complicated models of the heavens--celestial spheres--that illustrated the "wandering" of the sun, the moon, and the planets against the fixed position of the stars.

The process of measuring time has progressively become more accurate, and the devices more localized ever since.

In our time, the dates and time are predominately measured by mechanical, and now mostly by electric and electronic clocks.



Mechanical clocks with pendulum.


Pendulum clocks have been used to keep time since 1656, and they have not changed dramatically since then.

Pendulum clocks were the first clocks made to be accurate.

When you look at a pendulum clock from the outside, you notice several different parts that are important to the mechanism of all pendulum clocks:

There is the face of the clock, with its hour and minute hands .

There are one or more chained weights to power the clock; or a keyhole in modern clocks that are used to wind a spring inside.

And, of course, there is the pendulum itself.

In most wall clocks that use a pendulum, the pendulum swings once per second. In small cuckoo clocks the pendulum might swing twice a second. In large grandfather clocks, the pendulum swings once every two seconds.


Digital clock with crystal oscillators


There are variety of methods that one can design and construct a digital clock.
One method is to use discrete components, known as standard cells or shelf devices.
A second method is to use integrated circuits, known as chips.
A third method is to use programmable devices such as FPGAs.

Integrated circuits are much more efficient and commercially available. You can simply buy a clock chip and build the entire clock by adding other components such as display and power supply to it.