# Project report NAND Gate

## Acknowledgement

I would like to express my special thanks of gratitude to my teacher (Name of the teacher) as well as our principal (Name of the principal)who gave me the golden opportunity to do this wonderful project on the topic (Write the topic name), which also helped me in doing a lot of Research and i came to know about so many new things I am really thankful to them.

Secondly i would also like to thank my parents and friends who helped me a lot in finalizing this project within the limited time frame.

## Aim

Aim of this project is to demonstrate the working of two input NAND gate using Transistor and LED.

## Introduction

The Logic NAND Gate is a combination of a digital logic AND gate and a NOT gate connected together in series.

The NAND (Not – AND) gate has an output that is normally at logic level “1” and only goes “LOW” to logic level “0” when ALL of its inputs are at logic level “1”. The Logic NAND Gate is the reverse or “Complementary” form of the AND gate.

The Boolean expression for a logic NAND gate is denoted by a single dot or full stop symbol, ( . ) with a line or Overline, ( ‾‾ ) over the expression to signify the NOT or logical negation of the NAND gate giving us the Boolean expression of:  X¯.Y¯ = Z.

Then we can define the operation of a 2-input digital logic NAND gate as being

“If either X or Y are NOT true, then Z is true”

## NAND gate truth table ## Material required

Transistor:- Transistor is a semiconductor device that can both conduct and insulate. A transistor can act as a switch and an amplifier.
A transistor is a three terminal device. Namely,

1. Base: This is responsible for activating the transistor.
2. Collector: This is the positive lead.
3. Emitter: This is the negative lead.
Resistor:- The resistor is a passive electrical component to create resistance in the flow of electric current.
LED:- An LED produces light when electricity flows through.
Battery:- A 9V dc battery is used to power this circuit.
Battery snap connector:- To connect the battery terminals to the rest of circuit.
Soldering Iron:-  To solder the various components used in this project.
Switches:- For controlling the input to the circuit

## Circuit Diagram ## Working

In this project three transistors are used i.e. T1, T2, and T3. Input through switch X and Y are provided to T1 and T2. T3 is always connected to the supply.

• When X=0 Y=0

Both the transistor T1 and T2 goes to cutoff mode, forcing all the current to go through T3 in turn turning in LED. Hence Z=1

• When X=1 Y=0

In this case transistor T1 goes to saturation mode but transistor T2 remains in the cutoff mode as no base voltage is applied. As a result all the current is forced to go through T3 which in turn turns on the LED. Hence Z=1

• When X=0 Y=1

In this case transistor T2 goes to the saturation mode but transistor T1 remains in cutoff mode as no base voltage is applied. As a result all the current is forced to go through T3 which in turn turns on the LED. Hence Z=1

• When X=1 Y=1

In this case both transistors T1 and T2 go to the saturation mode allowing all the current to pass through them. No current passes through T3 (as current prefers low resistance path). Hence Z=0