AIM:
To familiarise with logic gate IC packages and to verify the truth tables of those gates
COMPONENTS AND EQUIPMENTS REQUIRED:
ICs 7400,7402,7432,7486,7408 and IC trainer kit
THEORY:
LOGIC GATES:
In digital electronics a gate is a logic circuit with one output and one or more inputs. Most logic gates are available as integrated circuits.
AND GATE:
The AND gate performs logical multiplication more commonly known as AND operation. The AND gate output will be in high state only when all the inputs are in high states.
C=A.B
7408 is a digital IC in the TTL family and contains four AND gates .For this reason it is called quad two input AND gate. Every AND gate has two inputs in this dual inline package(DIP).Pin 14 is the supply pin. For standard TTL device to work properly, the supply voltage level must be between +4.75 and +5.25v.This is why +5v is the normal supply voltage specified for all TTL devices. Pin 7 is the common ground for the chip. The other pins are inputs and outputs.
OR GATE:
It performs logical addition. Its output will become high if any of the input is in logic high.7432 is a quad two input OR gate.
C = A+B
NOT GATE:
It performs a basic logic functions called inversion or complementation . The purpose of the inverter is to change one logic level to opposite level.IC 7404 is a hex inverter.
B = A’
NAND GATE:
A NOT gate following an AND gate is called NAND gate or NOT-AND gate. Its outputs will be low when all the inputs are in high state.7400 IC is a quad two input NAND gate.
C = (A.B)’
NOR GATE:
A NOT gate followed by an OR gate is called NOT-OR gate or NOR gate. Its output will be in low state if any of its input is high state.IC 7402 is a quad two input NOR gate.
C = (A+B)’
XOR GATE:
Its output will be high if one input is high state.IC 7486 is a quad two input XOR gate.
C = AB1+A1B
PROCEDURE:
1.Test all the components and IC packages using a digital IC tester.Also assure whether all the connecting wires are in good condition by testing for the continuity using a multimeter or a trainer kit. Continuity of wires can be tested using a trainer kit by shiorting a 5v supply in the trainer to an LED of the panel. If wires are good LED will glow.
2. Verify the dual in line package(DIP) pinout of the IC before feeding the inputs.
3. Set up the circuit and observe the output.
