Practical Uses of Logic Gates

Logic gates are fundamental building blocks of digital circuits and are used in a variety of electronic devices and systems. This presentation contains some examples of practical uses of logic gates. This presentation was prepared for a seminar in School of Engineering, Pokhara University, Nepal.

1. A PRESENTATION ON
“PRACTICAL USES OF LOGIC GATES”
By : Abiral Gautam

2. LOGIC GATES
•The logic gates are the devices that performs basic logical functions that are
fundamental to digital circuits.
•It performs a logical operation on one or more binary inputs and produces a
single binary output.

3. TYPES OF LOGIC GATES
•There are 7 types of logic gates.
•Out of 7 types of logic gates, 3 are basic logic gates (AND,OR,NOT) and 4 of
them are derived logic gates (NAND, NOR, X-OR, X-NOR).
•Derived logic gates are the gates that are derived from the basic logic gates.

4. TYPES OF LOGIC GATES

5. WHAT DOES LOGIC GATES LOOK LIKE ?

6. HOW LOGIC GATES ARE MADE ?
•Made using digital circuits and components like Transistor, Resistor and Diodes.
•Specific implementation depends on the type of gate and technology used.
TransistorResistorDiode

7. WHAT ARE THE USES OF LOGIC GATES?

8. AND GATE
•AND Gate performs logical AND operation.
•The output of AND gate is True only when its all input are true. If one input is
False then the output is also False.
•Boolean Expression : Y = A.B where A and B are inputs and Y is output
•Mostly used in digital data transmission for either allowing or disallowing the
data through a channel
•Used in alarm circuits, automatic temperature-regulating circuits, etc.

9. AND GATE USE IN BURGLAR ALARM
Motion Sensor
Alarm Switch
AND GATEBurglar Alarm
On/Off
On/Off
If the alarm switch is ‘ON’ and if a burglar enters into the room, then he/she will set the
motion sensor switch “ON”, the alarm is activated.

10. OR GATE
•OR Gate performs logical OR operation.
•The output of OR gate is True if atleast one input is True
•Boolean Expression : Y = A + B where A and B are inputs and Y is output
•If occurrence of one or more than one event is to be detected and action is to
be taken then OR gate can be used.

11. OR GATE USE IN DORBELL SYSTEM
Front Door Switch
Back Door Switch
Doorbell
If either the front door switch or the back door switch is pressed, the doorbell rings.
OR GATE

12. NOT GATE
•NOT Gate performs logical NOT operation.
•The output of NOT gate is True if the input is false and vice-versa
•Boolean Expression : Y = A’ where A is input and Y is output
•NOT gate is mostly used in temperature control systems.

13. NOT GATE USE IN TEMPERATURE CONTROL SYSTEMS
Temperature Sensor
(Above 20 ℃) Heating System
If the temperature is above 20 ℃then the heating system turns off .
If the temperature is below 20 ℃then the heating system turns on.
NOT GATE
On/Off

14. NAND GATE
•NAND Gate is the combination of NOT gate and AND gate.
•The output of NAND gate is False if only all input is True.
•Boolean Expression : Y = (A.B)’ where A and B are input and Y is output
•NAND gate are used in Failure Detection System, Freezer warning buzzer, etc.

15. NAND GATE USE IN FAILURE DETECTION SYSTEM
Alarm
While all the devices are working the input to the NAND Gate are 111 so the output is 0.
But if a device stops working then the output of NAND gate will become 1 and the alarm
will ring.
Device 1Device 2Device 3

16. NOR GATE
•NOR Gate is the combination of NOT gate and OR gate.
•The output of NOR gate is True if only all input are False else the output will
be False.
•Boolean Expression : Y = (A + B)’ where A and B are input and Y is output
•NOR gate are used mostly in Mixer Tanks in Industries.

17. NOR GATE USE IN MIXER TANK
Ingridient 2
Ingridient 1
Motor
Mixer tank
When the both ingridients are filled up in the tank the input will be 0 and the NOR gate will give
output 1 and the motor of the mixer starts

18. X-OR GATE (EXCLUSIVE OR)
•X-OR gate is a digital logic gate that gives true output if the number of true
inputs are odd else it will give false output.
•Boolean Expression : Y = A’ . B + A . B’ where A and B are input and Y is output
•X-OR gate can be used in the conveyer belts in industries.

19. X-OR GATE USE IN CONVEYER BELT
BoxBoxBoxBox
Conveyor Belt
Controller
Color Sensor
Motor
In the conveyer belt above, when the orange boxes are detected by the color sensor then the both inputs
will be 1 but when a black box arrives the color sensor input will change to 0 which makes the output of
X-OR gate 1 and the motor will activate and the black box will be kicked out.
Orange color is set true

20. X-NOR GATE (EXCLUSIVE NOR)
•X-NOR gate is a digital logic gate that gives output the complement of output
of X-OR gate
•Boolean Expression : Y = A . B + A’ . B’ where A and B are input and Y is output
•X-NOR gate are used mainly in Parity Checkers, Computers, Mobile Phones,
and are used for error detection in data transmission systems like Anti-Lock
Braking System, Engine Control Unit, Heart Monitors, ECG, etc.

21. X-NOR GATE USE IN PARITY CHECKER CIRCUIT
A
B
C
P
Cp
ABCPCp
00001
00010
00100
00111
01000
01011
01101
01110
ODD PARITY CHECKER
If the 4-bit received message contains even number of 1 then the value of Parity Checker (Cp) is 1 which means
error and the data is invalid and If the 4-bit message contains odd number of 1 then the value of Cp is 0 which
means no error.

22. THANK YOU