MNR SCHOOL OF

EXCELLENCE
CERTIFICATE
This is to certify that Mst. Pawan Sunil Jadhav a student of
class XII- C , Roll NO. - 19 has successfully completed a
Project work on “LOGIC GATES” during the year 2025-26
in partial fulfillment of PHYSICS practical exam.

External Internal Principal

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 ACKNOWLEDGEMENT
I would like to express my gratitude towards my school
Principal MR.PRASHANT who was a constant source of
motivation & inspiration for the student.
I would like to thank my school for providing me the platform to
glow & excel. I would like to thank my Physics teacher Sheetal
Jadhav who guided me for explaining the concepts of the
project & theory.
I would like to express my gratitude to the lab assistant sir who
constantly helped me in laboratory with lab equipments.
I would like to thank my parents for providing me the means to
complete this project and each & every person who has been
supporting and motivating me throughout the project.

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 INDEX
S.No. Topic Page No.
1. Aim And Apparatus 4

2. Theory 5

3. Procedure 6

4. Conclusion 8

5. Precautions 9

6. Applications 10

7. Bibliography 11

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 AIM AND APPARATUS
Aim :- To make AND, OR, and NOT logic gates using simple
components like diodes, resistors, and a transistor, and to test their
outputs using LEDs.

Apparatus :-
 2 Push-button switches (for input)
 1 NPN transistor
 3 LEDs
 3 Diodes (e.g., 1N4148 or 1N4007)
 4 Resistors (330Ω and 10kΩ)
 Breadboard
 9V battery and clip
 Connecting wires

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 THEORY
Logic gates are the fundamental building blocks of digital circuits.
They take binary inputs (0 for LOW and 1 for HIGH) and produce a
binary output based on specific logic rules. Logic gates are used in
computers, calculators, mobile phones, and almost every digital
device.

Each logic gate works according to Boolean algebra and has a

unique truth table that shows how the output depends on the inputs.
In this project, we created AND, OR, and NOT gates using basic
electronic components like diodes, resistors, push buttons, and a
transistor, instead of using logic gate ICs. This helps us understand
how these gates function at the component level.

 AND Gate:
 Gives output HIGH (1) only when both inputs are HIGH.

 Made using two diodes and a resistor.

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  OR Gate:
 Gives output HIGH when any one or both inputs are HIGH.

 Made using two diodes and an LED with resistor.

 NOT Gate:
 Gives an output that is the opposite of the input.

 Made using an NPN transistor and a resistor.

We used LEDs to check the output. If the LED glows, it shows

output is HIGH (1), and if it stays off, the output is LOW (0).

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 PROCEDURE
 For Setting up AND Gate
1. Set up Inputs: Place two push-button switches on the
breadboard, representing inputs A and B.
2. Connect Diodes: Connect each push-button to a diode. The
cathode (striped end) of both diodes should be connected to a
common point.
3. Attach Resistor: Connect a 330Ω resistor from this common
point to ground (GND).
4. LED Connection: Connect an LED between the common point
and the +9V supply.
5. Test the Gate: When both buttons are pressed (both inputs are
HIGH), the LED will glow, indicating the output is HIGH. For
all other combinations of input, the LED will stay off.

 For Setting up OR Gate

1. Set up Inputs: Place two push-button switches for inputs A
and B.
2. Connect Diodes: Connect each push-button to a diode. The
anode (non-striped end) of both diodes should be connected
together.
3. LED and Resistor: Connect the common point (where both
diodes meet) to an LED (with a 330Ω resistor) that is connected
to ground (GND).
4. Test the Gate: The LED will glow if either or both inputs are
HIGH (i.e., if any button is pressed).

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 For Setting up NOT Gate
1. Set up Input: Place a push-button switch on the breadboard
for the input A.
2. Transistor Base Connection: Connect one terminal of the
push-button to the base of the NPN transistor (e.g., BC547)
through a 10kΩ resistor.
3. Transistor Emitter Connection: Connect the emitter of the
transistor to ground.
4. Transistor Collector Connection: Connect the collector of the
transistor to an LED (with a 330Ω resistor) and then to +9V.
5. Test the Gate: When the push-button is not pressed (input is
LOW), the LED will be ON. When the push-button is pressed
(input is HIGH), the LED will be OFF, indicating that the
transistor switches the output.

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 CONCLUSION
In this project, we successfully built AND, OR, and NOT gates using
basic electronic components such as diodes, resistors, and an NPN
transistor, instead of using pre-built ICs. By constructing and testing
these gates, we gained a deeper understanding of their behavior and
how they process binary inputs to produce outputs based on logical
conditions.
 The AND gate required both inputs to be HIGH for the output to
be HIGH.
 The OR gate gave a HIGH output when any one of the inputs
was HIGH.
 The NOT gate inverted the input, providing the opposite output.

This hands-on approach not only helped us understand the

theoretical concepts of logic gates but also showed how digital
circuits can be constructed using simple components. The project
emphasizes the importance of logic gates in the foundation of
digital electronics, which are integral to systems like computers,
communication devices, and even everyday appliances.

Through this project, we also observed the practical applications of

logic gates in real-world systems like alarm circuits, control
systems, and computing devices.
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PRECAUTIONS
1. Component Placement: Ensure diodes, resistors, and
transistors are placed correctly (check orientation).
2. Power Supply: Use a 9V battery with correct polarity.
3. Resistor Usage: Use 330Ω resistors with LEDs to avoid
overcurrent.
4. Check for Short Circuits: Inspect the circuit for shorts
before powering it on.
5. Handle Transistors Carefully: Avoid static or heat damage
to transistors.
6. LED Connection: Connect the long leg of the LED
to +9V and the short leg to ground.
7. Button Function: Ensure push-buttons are working and
correctly wired.
8. Power Off Before Adjustments: Always turn off power
before adjusting the circuit.

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APPLICATIONS
Applications of Logic Gates
1. Automatic Street Lights (Using NOT Gate):
 Logic gates can control street lights.
 When it's dark, a sensor gives a LOW signal.
 The NOT gate turns this into HIGH and switches ON
the light.
2. Burglar Alarm System (Using OR Gate):
 If any one of the sensors (like door or window sensors)
is triggered (HIGH input), the OR gate gives a HIGH
output.
 This output turns ON an alarm or buzzer.
3. Password Protection System (Using AND Gate):
 Multiple buttons (inputs) need to be pressed correctly at
the same time.
 Only then the AND gate gives HIGH output, which can
unlock a door or start a machine.
4. Fan or Light Control System (Using AND Gate):
 Used in industrial control panels.
 Fan turns ON only if temperature is high AND system
is active.
5. Digital Calculators and Computers:
 All digital devices (calculators, computers, smartphones)
use logic gates to perform calculations and processing.
 They are the basic building blocks of CPUs and memory.

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BIBLIOGRAPHY
My references were:
1) NCERT textbook class 12
2) NCERT physics lab Manual
3) www.google.com

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