LM35 Thermometer With LCD, Fan, Speaker and LED

Let everyone to know the precise temperature inside the house and everywhere in the house. Automatically turn on USB fan, and high temperature sound warning. LED light warning.

Arduino Leonardo

Breadboard

Jumper Wires

USB Cord

LM35 temperature sensor

USB fan

16*2 LCD screen

1 red LED, 1 green LED

1 speaker

30 Wires

Welding torch

Box

Powerbank

Connect supplies voltage to 5V

Connect output to A2

Connect Ground to GND

make sure LM35 face your Leonardo boards.

Connect LCD to Leonardo

Connect fan to board

extend LED wires

Connect speaker

GND to GND

VCC to 5V

SDA to SDA

SCL to SCL

Extend your LED make it go though the box

Do the same thing to red LED

Connect to digital 12 and GND

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd_I2C_27(0x27,16,2); // set the LCD address for a 16 chars and 2 line display

void setup(){  // put your setup code here, to run once:
  lcd_I2C_27.init (); // initialize the lcd
  lcd_I2C_27.backlight();
  pinMode( 7 , OUTPUT);
  pinMode( 8 , OUTPUT);
  pinMode( 12 , OUTPUT);
}

void loop()
{
  int sensorValue = analogRead(A0);
  float millivolts = (sensorValue / 1024.0) * 5000; 
  float celsius = millivolts / 10;
  lcd_I2C_27.setCursor(2, 0);
  lcd_I2C_27.print( "Temperature" );
  lcd_I2C_27.setCursor(4, 1);
  lcd_I2C_27.print(celsius);
  lcd_I2C_27.setCursor(10, 1);
  lcd_I2C_27.print("C");
 
  if ( celsius >= 28 ) {
    digitalWrite( 8 , HIGH );
    digitalWrite( 7 , LOW );
    digitalWrite( 12 , HIGH );
    tone(11, 1000, 100);
  }
  else
  {
    digitalWrite( 7 , HIGH );
    digitalWrite( 8 , LOW );
    digitalWrite( 12 , LOW );
  }
  delay(50);
}

When temperature over 28degC, the LED with change from Green to RED with Speaker alert, Fan will start to cooling,

When temperature back to under 28degC, the LED will change back to Green, fan and Speaker will stop.