## Introduction: 1 Bit Full Adder

An adder is a digital electronic circuit that performs addition of numbers. Adders are used in every single computer's processors to add various numbers, and they are used in other operations in the processor, such as calculating addresses of certain data.

In this instructable, we are going to construct and test the one bit binary full adder. The attached figure shows the block diagram of a one bit binary full adder. A block diagram represents the desired application and its various components, such as inputs and outputs.

Inputs: A, B, Carry in (Cin)

Outputs: Carry out (Cout), Sum (S)

__Parts Needed:__

9V battery

Batter Connector

5V regulator

IC chips: 74LS136, 74LS08, 74LS32.

(Optional: 74LS00) *If you do not have an XOR, 74LS136, IC Chip*

2 330 Ohm resistors

2 LED's (Different colors preferred)

DIP switch

10 Kilo Ohm resistor bank

Wires as needed

## Step 1: Truth Table, Derived Boolean Function, and Schematic

The truth table of a one bit full adder is shown in the first figure; using the truth table, we were able to derive the boolean functions for both the sum and the carry out, as shown in the second attached figure. Furthermore, the derived boolean function lead us to the schematic design of the one bit full adder. Finally, I did not have any XOR IC chips, so I used the XOR mixed gates equivalent, which is shown in the last figure.

## Step 2: Implementation on a Breadboard

If the switch is up, then it is off.

If the switch is down, then it is on.

The White wire represents A.

The Blue wire represents B.

The Yellow wire represents Carry in (Cin).

The Green LED represents the Sum.

and the Red LED represents the Carry Out (Cout).

Can you please explain how you used a two input OR gate as a Three input OR gate.

I used two 2-input OR gates to perform the operation of a 3-input OR gate.

Is the OR gate a three input?

No, it is a 2-input. I used the 74LS32 IC, which is a quadruple 2-input OR gates.

A circuit diagram would be helpful.

The circuit diagram is attached in this instructable (I attached it to this comment as well). Just make sure the IC chips are powered by a +5V source, and are grounded.

Here is the URL for the 74LS136 IC: http://www.ti.com/lit/ds/symlink/sn74ls136.pdf

Hope this helps.