“To design & construct Full Adder by Using Half Adders & To Verify its Truth Table”
“To design & construct Full Adder by Using Half Adders & To Verify its Truth Table”
1. Objective:
The main objective is to design and verify the truth
table of
i. Full Adder
2. Components:
i.
Bread Board
ii.
Connecting Wires
iii.
LED iv. Battery
v. 3 IC’s
a. IC
7486 for XOR Gate
b. IC
7408 for AND Gate
c. IC
7432 for OR Gate
3. Introduction:
3.1.Bread Board:
A bread board is an electronic board into which the
electrical components like diodes and resistors are placed. The sockets of
bread board are sturdy and rugged. Diodes or other electrical components should
be placed without making any damage to the board.
3.2.Integrated Circuits:
A circuit of transistors, resistors, and capacitors
constructed on a single semiconductor wafer or chip, in which the components
areinterconnected to perform a given function. IC’s consume very little
current, generate comparatively little heat, and are far more shock-proof and
reliable than the older discrete-component circuits.
An integrated circuit consists of a number of circuit
components (e.g. transistors, diodes, resistors etc.) and them inter
connections in a single small package to perform a complete electronic
function. These components are formed and connected within a small chip of
semiconductor material. IC’s can be used as advanced logic gates. Some IC’s
description is given below which can be used for logic gates.
3.3.Light Emitting Diodes:
A light-emitting diode (LED) is a semiconductor
device that emits visible light when an electric current passes through it.
LED’s convert electrical energy to light energy. In electronics, polarity
indicates whether a circuit component is symmetric or not. Being diodes, will
only allow current to flow in one direction. And when there’s no current-flow,
there’s no light. The positive side of the LED is called the “anode” and is marked by having a
longer “lead,” or leg. The other, negative side of the LED is called the “cathode.”
3.4.Full Adder
A full adder is a combinational circuit that forms
the arithmetic sum of three input bits. A full adder consists of three inputs
and two outputs. Two of the input variables full adder, denoted by x and y,
represent the two significant bits to be added. The third input, z, represents
the carry from the previous lower significant position. Two outputs of full
adder are necessary because the arithmetic sum of three binary digits’ ranges
in value from 0 to 3, and binary 2 or 3 needs two digits. The two output of
full adder are designated by the symbols S (for sum) and C (for carry). The
binary variable S gives the value of the least significant bits of the sum.
4. Circuit Diagram:
5. Experimental Setup:
6. Experimentation:
1. First
of all, suitable IC’s for XOR ,OR and AND gate are chosen, i.e. IC 7486 ,7432
& 7408 respectively.
2. Inserted
IC’s on the bread board.
3. As
there are 14 pins on IC, 7th pin is grounded and a positive
potential is applied to the 14th pin via a battery of potential less
than 5V.
4. First
Input A of XOR is connected with first input of first AND gate.
5. Second
input B of XOR is connected with the second input of first AND gate.
6. Output
of first XOR is given to the first input of second XOR, while its second input
is left to consider it carry .
7. The
first input of second XOR is connected to the first input of second AND gate,
while second input of second XOR is connected to the second input of AND gate.
8. First
LED is inserted on bread board with its positive terminal connected to the
output 
of second XOR gate and negative signal is
given to the other terminal.
of second XOR gate and negative signal is
given to the other terminal.
9. The
outputs of both AND gates are given to the OR gate as its two inputs.
10. Second
LED is inserted on bread board with its positive terminal connected to the
output of OR gate and negative signal is given to the
other terminal.
11. Then
one by one checked all the eight possible combination of three inputs so that
truth table can be verified.
12. Truth
table is drawn.
7. Observations
& Calculations:
The truth table for Full Adder which we have observed
is shown below:
A
|
B
|
Summaation
|
||
0
|
0
|
0
|
0
|
0
|
0
|
0
|
1
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
0
|
0
|
0
|
1
|
1
|
1
|
0
|
1
|
0
|
1
|
0
|
1
|
1
|
0
|
0
|
1
|
1
|
1
|
0
|
1
|
1
|
1
|
1
|
1
|
8. Results & Discussion:
We have designed Full Adders combining two half
adders in a suitable way. As we have also verified the truth tables of full
adders we can deduce some main points from this. The total OR , XOR & AND
logic gates in IC’s 7432 & 7408 respectively are 4. The whole circuit is
OFF when all of the inputs are zero, and ON when all of these are OFF.
9. Conclusion:
Through this experiment we have designed Full Adders
by using Half Adders and their truth tables are verified by using IC’s inserted
on bread board along with LED to show OFF or ON status of output.
10. References:
I.
http://logic.ly/lessons/nor-gate/
II.
http://whatis.techtarget.com/definition/light-emitting-diode-LED
III.
http://isweb.redwoods.edu/instruct/calderwoodd/diglogic/full.htmhttp://www.bscshortnote.com/what-is-full-adder/
Comments
Post a Comment