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: deg...

Hello! friends

Welcome to my another Adder and Subtractor project. It's a topic of Digital And Logic Design by Morris Mano (fifth edition) with the help of this you'll know how its work in reality.

So let's get started.

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Step 1: Circuit Diagram

With the help of this diagram we build our Adder/Subtractor project.

Step 2: Materials

You'll need

Some pieces of wire

Soldering wire and solder

Vero board

Resistors: (330ohms x 13) and 1k

Ic's: lm7805, 74ls86 and 74ls38 with bases

Switches: spst x 9 and dpst x 1

Led's: red x 9 and yellow x 5

Step 3: Component Placing

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

Step 4: Soldering and Jumper Wires

Here it is the soldering and jumper wires.

Step 5: Finish

After its look like this.

Step 6: Examples

When you push the switch on left side then its work as a adder and on left side as a subtractor you can see on image. I uploaded a video on next step i'm sure it will clear your concept.

Step 7: Video

Thanks for watching.

I hope you guys like it.



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    24 Discussions


    1 year ago

    We would appreciate the circuit schematic for a 14-pinned IC instead of 16. I couldn't find one in the local market!


    Question 1 year ago

    Hey, thanks for sharing.
    Could you please share the diagram for using an 74ls38 with only 14 pins? Thanks!


    3 years ago

    great project

    can i place your project on my website.

    i'm working on a website which is related to electrical projects.

    i also mention your name.

    plz reply

    1 reply

    k let me clear you just focus on a diagram lets get started with upper 4 led's (A0, A1, A2 and A3) will be connected with 74ls38

    A0 is connecting with the pin 10 of (74ls38)

    A1 is connecting with the pin 8 of (74ls38)

    A2 is connecting with the pin 3 of (74ls38)

    A3 is connecting with the pin 1 of (74ls38)

    lower 4 led's (B0, B1,B2 and B3) will be connected with 74ls86

    B0 is connecting with the pin 2 of (74ls86)

    B1 is connecting with the pin 5 of (74ls86)

    B2 is connecting with the pin 10 of (74ls86)

    B3 is connecting with the pin 14 of (74ls86)

    now let's talk about the jumper who's connected with IC to IC

    (74ls86) pin no 6 connected with (74ls38) pin no 7

    (74ls86) pin no 11 connected with (74ls38) pin no 16

    (74ls86) pin no 13 and (74ls38) pin no 5 connected with +ve terminal of 9 volt battery and other connections are shown in a diagram clearly.

    I hope it will help you.


    4 years ago on Introduction

    good day sir. i just would like to ask how to connect the circuit into the ic 74ls38, which has 14pins because in your finish project or circuit it has a 16pin 74ls38. i am just a newbie sir with digital electronics and i want to build this one,,, so please could you help me sir. thank you sir.

    1 reply