Discrete Diodes Used to Build Digital Clock

The project aims to build a digital clock by using an Arduino while lighting up a group of discrete LEDs wherein each segment is driven by transistor since they require more power.

The display of the clock is made up of six 7-segment displays and each digit is made of seven segments with 3 parallel LEDs making up every segment. This results to having 21 LEDs in each 7-segment display with a total of 126 LEDs for all six digits. Since this clock utilizes 130 LEDs, the other 4 LEDs are designed to be used as dots for the hours, minutes, and seconds to be separated. All the negative leads are connected together which produces a common cathode display.

A technique known as multiplexing is applied in the design since this kind of display requires a large amount of pins to power it out. Multiplexing creates an illusion that all the displays are working in the same time by switching between the digits one by one very fast.

The 4017 decade counter is used for the scanning of the display. it connects the grounds one by one to scan the display.

Rest of the project