Digital Led Chaser

This circuit uses digital circuits such as a demultiplexer and a binary counter to create patterns of “moving” led lights. This basic circuit is really cool when used in the dark or to light up a sign of some sort, as it creates a cool pattern that catches the eye.

The main part of the circuit is the demultiplexer 74ls138, we are going to connect the least significant bits of the output of the counter, that will select one of the pins of the demultiplexer as the output, lighting the led connected to it. The counter is wired only to count, and a clock pulse is needed to perform that function (the clock circuit is not included, but any will do, as long as it isn’t too noisy)

One adaptation to use is to connect the most significant bit of the counter to another series of leds, enabling or disabling one of them so that the pattern will follow 16 leds instead of the only 8 shown here.

Circuit source: Electronic circuits for beginners, by Zaakid Mata

1 – 74ls138 demultiplexer
1 – 74ls163 digital counter
8 – leds (red)
8 – resistors (220 ohm)
1 – clock signal generator (diagram not included)

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