Active Low Decoder (BCD Decimal)




Introduction: Active Low Decoder (BCD Decimal)

About: I am a student of BSCS but I'm interested in electronics that's why I would like to think about innovative ideas and try to build my ideas into reality and i also interested in making a robots. email id: degen…

Hello! Instructables

Welcome to my active low decoder (BCD Decimal) project. It's a topic of Digital And Logic Design by Morris Mano (fifth edition).

I just build it as a hardware.

Step 1: Basics

Before starting this project you'll need to know how its work. So with the help of this picture you can understand easily what i mean actually if you didn't understand yet no problem at the last step i uploaded a small video about active low decoder.

Let's get started.

Step 2: Circuit Diagram

Here it is the circuit diagram of active low decoder.

Step 3: Parts

You'll need

Vero board

IC's: 74ls42 with base and LM7805 (regulator)

Resistors: 330ohm x 10, 1k x 5

Leds: green x 10 and red

Switches: spst x 9 (4 spst is optional)

9 volt battery with connector

Step 4: Component Placing

Place the components on vero board according to circuit diagram then soldering it.

Step 5: Soldering

After soldering and connecting jumper wires its look like this.

Step 6: Complete

Now Active low decoder (BCD decimal) is ready to use. In next step a small review about active low decoder in a video is clear your concepts.

I hope you like my DLD active low decoder project.

Step 7: Active Low Decoder (video)

Thanks for watching.

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    7 years ago on Introduction

    Good Job Tanks :)

    I wrote a conversion program to the bases Decimal, Binary, Hexadecimal 32 BIT.

    the program that was written in Delphi also displays time in binary it runs on Windows.

    If you are interested, here is the download link:

    You click on the link to download the ZIP (sources are included with the executable program).

    as the program is in French, Here is the translation of the aid:

    DBH_Conv That is a program converts a number of 32Bit Within three number bases:




    aussi it displays a small binary clock

    French to English program displayed:

    Number of Entree's Translate ==> Enter the Number to be Translate

    Translation into three bases ==> 3 Bases Conversion

    Help ==> Help


    Enter the number to put into one of three bases (Decimal, Hexadecimal, Binary) in the white box

    Then click the button That base D, B or H

    the result is displayed in the two --other base


    7 years ago on Introduction

    I remember making something like this in my digital design class a few years back. So much fun!