Half Adder Circuit Using Logic Gates

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Contents hide
1 Introduction:
2 Half Adder Logic Gate Diagram:
3 Circuit Diagram:
4 Construction & Working:
5 Applications:

Introduction:

An adder is known to be any device or circuit that adds two or more inputs and generates the result. In digital electronics, an adder is a circuit built using logic gates in order to perform the addition of binary bits. It takes binary bits as input and produces a two-bit binary result by adding them. The adders are divided into two types that are, a half adder circuit and a full adder circuit.

Half adder circuit adds two-bit binary input and produces a two-bit binary output, but it cannot add a carry-in bit while the full adder circuit can add a carry-in bit along with the two-bit binary input. Half adder circuit is generally a simple circuit than the full adder circuit which is more complex.

We will discuss the complete working principle of the half adder circuit in this post along with its circuit diagram and applications.

Half Adder Logic Gate Diagram:

Two input XOR and two AND gates combine to form a half adder circuit. The truth table for the output of the logic gate is given below:

Circuit Diagram:

Half-adder-Circuit
Half adder circuit is built using the two ICs (7486 & 7408) combined together.

Construction & Working:

The half adder circuit is built using XOR gate IC 7486 and logic AND gate IC and both are two-input logic gate ICs. When the 5V VCC and ground is supplied to the logic gate IC and the binary inputs A and B are connected to the XOR logic gate and the logic AND gate IC, the output is obtained at the pin3 of both ICs. The output of the XOR gate is connected to the LED1 through a resistor R1 and the output of AND gate is connected to the LED2 through resistor R2. The LEDs are used to indicate the HIGH and LOW logic.

It takes two inputs A and B and gives two outputs Sum and Carry.

  • Sum   = A ⊕ B
  • Carry = A . B

Applications:

The applications of half adder circuit are described as under:

  • The basic application is a full adder circuit, which is built by combining half adder circuits.
  • It is used in calculators for performing calculations.
  • It is also applicable for measuring addresses and tables.
  • The binary bits can be added using half adders which are used by the ALU system.
  • Hence, in digital electronics half adders plays a major role in performing addition.

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