In the 21st century, the world has become a place where every second counts. We must finish whatever we need to finish within a specified amount of time. The routines of work have become very important for modern people. In an industry, the precise control of hours, minutes and seconds has a huge influences on the quality of goods produced during the industrial production process. For example, the precise control of the cooling time in a steel furnace has an influence on the rigidity and the ductility of the produced steel, the control of the firing time for ceramic arts affects the aesthetics and durability of the artworks, the control of the fusion time for the production of alloy steel affects its internal grain structure and strength, etc. This paper can be divided into two parts. In the first part, we introduce the 555 astable multistage oscillator. The external circuit of the oscillator is adjusted to match the one-way behavior of the diode, allowing the oscillator to output digital pulses with an equal duty cycle. The second part we describe a digital clock composed of two mod 60 and one mod 24 counter. When the digital pulse wave output from the first part of the oscillator is transmitted to the second part, the second part of the digital clock starts to function.