Introduction

A Digital Thermometer is an electronic device used to measure and display temperature in digital form. Unlike analog thermometers, digital thermometers provide faster, more accurate, and easy-to-read temperature measurements.

This project demonstrates how temperature can be measured using electronic sensors and microcontrollers.

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Objective of the Project

The main objectives of this project are:

• To measure ambient temperature accurately.
• To display temperature in digital format.
• To understand temperature sensing techniques.
• To interface sensors with a microcontroller.

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Working Principle

The digital thermometer works on the principle of temperature sensing and analog-to-digital conversion.

Basic Operation

1. A temperature sensor (LM35) senses ambient temperature.
2. The sensor outputs voltage proportional to temperature.
3. Arduino converts the analog voltage into digital data.
4. Temperature value is calculated and displayed.

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Components Required

• Arduino Uno
• LM35 Temperature Sensor
• 16×2 LCD Display (optional)
• Potentiometer (10kΩ)
• Jumper Wires
• Breadboard
• Power Supply (5V)

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Circuit Diagram

Connections

LM35:
VCC -> 5V
GND -> GND
OUT -> A0

LCD (16x2):
RS -> D7
EN -> D6
D4 -> D5
D5 -> D4
D6 -> D3
D7 -> D2
VSS -> GND
VDD -> 5V

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Arduino Code for Digital Thermometer

#include <LiquidCrystal.h>

LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

int tempPin = A0;

void setup() {
  lcd.begin(16, 2);
  lcd.print("Digital Thermo");
}

void loop() {
  int sensorValue = analogRead(tempPin);
  float voltage = sensorValue * (5.0 / 1023.0);
  float temperature = voltage * 100; // LM35

  lcd.setCursor(0, 1);
  lcd.print("Temp: ");
  lcd.print(temperature);
  lcd.print(" C");

  delay(1000);
}

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Code Explanation

• Arduino reads analog value from LM35.
• Voltage is converted to temperature.
• Temperature is displayed on LCD.
• Display updates every second.

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Advantages

• Accurate temperature measurement
• Fast response time
• Easy to read
• Compact and portable

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Applications

• Medical thermometers
• Weather stations
• Home automation
• Industrial monitoring
• Electronic devices

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Future Enhancements

• IoT-based temperature monitoring
• Mobile app display
• Data logging
• Temperature alerts

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Conclusion

The Digital Thermometer is a practical and educational electronics project that demonstrates how sensors and microcontrollers work together to measure real-world parameters. It is a perfect intermediate-level project with real-life applications.