Introduction
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.
Specifications
Operating voltage: 5v Digital technology: TTL
Theory
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)
Construction
This circuit can be build into a sign to illuminate it, or in any circuit or prototype board. Best effect is achieved if the leds are arranged in some pattern like a loop or “moving bar”
Alignment
None required
Use
This circuit can be used as illumination for a sign or frame. Also, depending on how you arrange the leds, a star sparkle can also be simulated. Other effects depend on the speed and arrangement of the leds.
Parts
- 1x - 74ls138 demultiplexer
- 1x - 74ls163 digital counter
- 8x - leds (red)
- 8x - resistors (220 ohm)
- 1x - clock signal generator (diagram not included)
Source
- Zaakid Mata, Digital Led Chaser Circuit