Digital Clock #001

Digital Clock #001 - a digital clock constructed with standard logic ICs

The page is to present a design of digital clock suited for hobby electronics.

A photo of the digital clock's test operation with a tentative wiring outside the circuit board before settled into a chasis.

Features.

Constructed with easily available, industry standard components only. All ICs used in the design are supplied from multiple manufacturers (Mar 2009).
Moderate circuit complexity. Component count remains relatively few (10 standard logic ICs, 3 linear ICs and some discrete components), even though the design does not use either digital clock LSI or programmable device such as MCU, PLD, etc.
4-digit LED numerical display indicates hours and minutes in 12-hour format.
AM/PM indicator is not given (however, it is easy to add an AM/PM indicator).
Any function to show the seconds is not given. Unlike some digital clocks whose colon separating hours and minutes blinks at e.g. 1Hz rate, the present clock does not blink the colon.
Setting clock time can easily be performed with three pushbutton switches.
32.768kHz tuning-fork quartz crystal resonator is used as a time-base element.
Operated with AC line power normally. Equipped with a battery back-up capability for power failure condition.

Design. The design of the clock is divided into three sections in drawing schematic diagrams.

Assembly. If you consider making a set of this digital clock, read remarks as a guide to digital clock #001 assembly page.

Usage. Usage of this digital clock is described in digital clock #001 usage page.

To customize design. Some hints for customizing design are given in digital clock #001 customization hints page.