Digital Clock: History and Types

A digital clock is a type of clock that bases its operations on a digital base time to generate the necessary frequency pulses (usually 1 Hz).

 The invention was made in 1956 by the Bulgarian engineer Petar Ptrov. The digital watch became popular when the microchip LEDs became cheap. It was a great revolution in the watch market field because it managed to manufacture watches much cheaper and more precise than those that were based on a mechanical operation.

To represent the time, many digital clocks use the seven segments LED, VFD or LCD to form each number shape. These clocks also include other elements to indicate whether the time is in the morning (AM) or in the afternoon (PM).

It is important to mention that digital clocks can be much smaller, useful and cheaper than mechanical based ones. Other important thing to consider is that many digital clocks are used as alarm clocks or as a radio.

Because of the low price of digital clocks, they have already been included in many other fields and products such as: cars, phones, computers, etc.

Operational system of a digital clock

 The accuracy of the clock depends on a time basis, which works with an oscillator or an adaptor that, on the basis of reference, generates a periodic signal.

The frequency divider is a digital circuit formed by a succession of counters to obtain a frequency of 1 Hz, which allows to display seconds. If you want to show tenths, the division will be at 10 Hz.


 Time base

The time basis type is so important that it usually gives the name to the type of clock. The most common are as follows:

-Patron of the network: It does not have the reference oscillator and use it as 50Hz (or 60Hz). It is the simplest, but it is quite accurate.

-Pattern of authority: The time base is a type of PLL, which works with any of the time radio stations. 

- Tuning Fork Watches: The oscillator is controlled by a feedback loop in the interspersed fretboard. It has already fallen into disuse.

-Quartz clock. Replace the tuning fork to a quartz resonator, usually at 32768 Hz, with the exact power of two that simplifies the frequency divider. Due to its stability and economy it is very common to be seen in common applications.

- Atomic clock: It is based on a feedback loop inside the cavity with molecules of the substance, which promotes the resonance of some of its atoms.




 To represent time, most digital watches use a seven-segment LED, VFD or LCD display for each of four digits. They also usually include other elements to indicate if the time is AM or PM, alarms, etc.




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