Shift Register Circuit

A 8 LEDs circuit operated by a SN74HC595N 8-bit shift register and a NE555 timer IC

Introduction

During my second year at university I became interested on learning more about electronics and integrated circuits, upon looking on my electronics components at home I found a SN74HC595N 8-bit shift register and decided to build a project based on this IC on my spare time.

Function:

A shift register is a circuit that uses several flip-flops, the output of one is connected to the next one. We can input data and store it.

I use it to control and store values on 8 LEDs with a manual control of three switches

Circuit Parts:

The circuit consists of:

8 LEDs
12 Resistors (220 ohms)
One SN74HC595N
3 switches
Jumper cables
Breadboard

Circuit Diagram:

Diagram

Working Circuit

Improvement

The circuit has three switches:

Clock
Data
Latch

In order to store data the data switch must be always pressed while the clock button when pressed send the data and the latch button turns the LEDs on or off.

While working with the circuit I experienced multiple unwanted LEDs being turned on when the clock button was only pressed once. To fix this undesirable extra bouncing effect of data being sent I designed, built and added a custom de-bouncer circuit with a NE555 timer.

NE555 Timer IC

Shift Register with NE555 de-bouncer OFF

Shift Register with NE555 de-bouncer ON

PCB Design

3D PCB Model

I decided to build the circuit on a PCB for practical testing and learning as well as to improve my PCB designing skills. I used an online software called EasyEDA to create the PCB

PCB routing and design

PCB was manufactured by JLCPCB and the components were soldered once it arrived.

Circuit Diagram

Finished model

VID_69700903_135242_511.mp4

Reflection

While this was an experimental project to learn more about shift registers it could have been improved by adding extra modules for a more interesting functionality, such as, an IF receiver so the data could be send with a remote controller, an extra shift register could be daisy chained increasing the output from 8 to 16 LEDs.

Also a 7-segment LED display could be added for an easier way to count.

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