CPU Fan for a P.C.

Do you know that if your computer gets extremely hot it can be bad for the computer and even yourself? Here's how to fix it! (don't worry It will still look good)

Feb 7, 2025

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CC BY-SA 4+

Devices & Components

16x2 LCD display with I²C interface

Arduino Uno Rev3

10 jumper wires 150mm male

Temperature Sensor: LM35dz

Breadboard 100x70

CPU fan 12 volt

Hardware & Tools

a laptop or a computer to test

Software & Tools

Arduino IDE

Project description

Code

4-speed cpu fan

1#include <LiquidCrystal_I2C.h>
2
3LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows
4
5// Pin Definitions
6const int tempPin = A0;   // LM35 sensor output connected to A0
7const int fanPin = 9;     // PWM pin connected to the fan (Pin 9 supports PWM)
8
9// Variables
10int tempReading = 0;      // Variable to store the raw temperature reading
11float temperatureF = 0;   // Temperature in Fahrenheit
12int fanSpeed = 0;  
13
14void setup()
15{
16  lcd.init(); // initialize the lcd
17  lcd.backlight();
18
19 
20
21  pinMode(A0, INPUT);
22  Serial.begin(9600);
23  pinMode(fanPin, OUTPUT);
24}
25
26void loop()
27{
28  lcd.clear();
29  if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 75) {
30    lcd.clear();
31    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
32    lcd.setCursor(0, 0);
33    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
34    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
35    lcd.setCursor(0, 1);
36    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
37    lcd.setCursor(5, 0);
38    lcd.print("F");
39    lcd.setCursor(5, 1);
40    lcd.print("C");
41    lcd.setCursor(7, 0);
42    lcd.print("Fan Speed");
43    lcd.setCursor(12, 1);
44    lcd.print("PWM");
45    lcd.setCursor(8, 1);
46    lcd.print(fanSpeed);
47    fanSpeed = 100;
48    if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 80) {
49     lcd.clear();
50     Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
51     lcd.setCursor(0, 0);
52     lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
53     Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
54     lcd.setCursor(0, 1);
55     lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
56     lcd.setCursor(5, 0);
57     lcd.print("F");
58     lcd.setCursor(5, 1);
59     lcd.print("C");
60     lcd.setCursor(7, 0);
61     lcd.print("Fan Speed");
62     lcd.setCursor(12, 1);
63     lcd.print("PWM");
64     lcd.setCursor(8, 1);
65     lcd.print(fanSpeed);
66     fanSpeed = 155;
67     if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 85) {
68       lcd.clear();
69       Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
70       lcd.setCursor(0, 0);
71       lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
72       Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
73       lcd.setCursor(0, 1);
74       lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
75       lcd.setCursor(5, 0);
76       lcd.print("F");
77       lcd.setCursor(5, 1);
78       lcd.print("C");
79       lcd.setCursor(7, 0);
80       lcd.print("Fan Speed");
81       lcd.setCursor(12, 1);
82       lcd.print("PWM");
83       lcd.setCursor(8, 1);
84       lcd.print(fanSpeed);
85       fanSpeed = 200;
86       if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 90) {
87         lcd.clear();
88         Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
89         lcd.setCursor(0, 0);
90         lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
91         Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
92         lcd.setCursor(0, 1);
93         lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
94         lcd.setCursor(5, 0);
95         lcd.print("F");
96         lcd.setCursor(5, 1);
97         lcd.print("C");
98         lcd.setCursor(7, 0);
99         lcd.print("Fan Speed");
100         lcd.setCursor(12, 1);
101         lcd.print("PWM");
102         lcd.setCursor(8, 1);
103         lcd.print(fanSpeed);
104         fanSpeed = 255;
105        }
106        delay(1000);
107     }
108     delay(1000);
109    }
110    delay(1000); // Wait for 2000 millisecond(s)
111  } 
112  else {
113    lcd.clear();
114    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
115    lcd.setCursor(0, 0);
116    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
117    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
118    lcd.setCursor(0, 1);
119    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
120    lcd.setCursor(5, 0);
121    lcd.print("F");
122    lcd.setCursor(5, 1);
123    lcd.print("C");
124    lcd.setCursor(7, 0);
125    lcd.print("Fan Speed");
126    lcd.setCursor(12, 1);
127    lcd.print("PWM");
128    lcd.setCursor(8, 1);
129    lcd.print(fanSpeed);
130    fanSpeed = 0;
131    delay(1000); // Wait for 2000 millisecond(s)
132  }
133
134 analogWrite(fanPin, fanSpeed);
135 Serial.print("Fan Speed: ");
136 Serial.println(fanSpeed);
137
138
139}

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows

// Pin Definitions
const int tempPin = A0;   // LM35 sensor output connected to A0
const int fanPin = 9;     // PWM pin connected to the fan (Pin 9 supports PWM)

// Variables
int tempReading = 0;      // Variable to store the raw temperature reading
float temperatureF = 0;   // Temperature in Fahrenheit
int fanSpeed = 0;  

void setup()
{
  lcd.init(); // initialize the lcd
  lcd.backlight();

 

  pinMode(A0, INPUT);
  Serial.begin(9600);
  pinMode(fanPin, OUTPUT);
}

void loop()
{
  lcd.clear();
  if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 75) {
    lcd.clear();
    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 0);
    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 1);
    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(5, 0);
    lcd.print("F");
    lcd.setCursor(5, 1);
    lcd.print("C");
    lcd.setCursor(7, 0);
    lcd.print("Fan Speed");
    lcd.setCursor(12, 1);
    lcd.print("PWM");
    lcd.setCursor(8, 1);
    lcd.print(fanSpeed);
    fanSpeed = 100;
    if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 80) {
     lcd.clear();
     Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
     lcd.setCursor(0, 0);
     lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
     Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
     lcd.setCursor(0, 1);
     lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
     lcd.setCursor(5, 0);
     lcd.print("F");
     lcd.setCursor(5, 1);
     lcd.print("C");
     lcd.setCursor(7, 0);
     lcd.print("Fan Speed");
     lcd.setCursor(12, 1);
     lcd.print("PWM");
     lcd.setCursor(8, 1);
     lcd.print(fanSpeed);
     fanSpeed = 155;
     if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 85) {
       lcd.clear();
       Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
       lcd.setCursor(0, 0);
       lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
       Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
       lcd.setCursor(0, 1);
       lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
       lcd.setCursor(5, 0);
       lcd.print("F");
       lcd.setCursor(5, 1);
       lcd.print("C");
       lcd.setCursor(7, 0);
       lcd.print("Fan Speed");
       lcd.setCursor(12, 1);
       lcd.print("PWM");
       lcd.setCursor(8, 1);
       lcd.print(fanSpeed);
       fanSpeed = 200;
       if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 90) {
         lcd.clear();
         Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
         lcd.setCursor(0, 0);
         lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
         Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
         lcd.setCursor(0, 1);
         lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
         lcd.setCursor(5, 0);
         lcd.print("F");
         lcd.setCursor(5, 1);
         lcd.print("C");
         lcd.setCursor(7, 0);
         lcd.print("Fan Speed");
         lcd.setCursor(12, 1);
         lcd.print("PWM");
         lcd.setCursor(8, 1);
         lcd.print(fanSpeed);
         fanSpeed = 255;
        }
        delay(1000);
     }
     delay(1000);
    }
    delay(1000); // Wait for 2000 millisecond(s)
  } 
  else {
    lcd.clear();
    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 0);
    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 1);
    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(5, 0);
    lcd.print("F");
    lcd.setCursor(5, 1);
    lcd.print("C");
    lcd.setCursor(7, 0);
    lcd.print("Fan Speed");
    lcd.setCursor(12, 1);
    lcd.print("PWM");
    lcd.setCursor(8, 1);
    lcd.print(fanSpeed);
    fanSpeed = 0;
    delay(1000); // Wait for 2000 millisecond(s)
  }

 analogWrite(fanPin, fanSpeed);
 Serial.print("Fan Speed: ");
 Serial.println(fanSpeed);


}

2-speed cpu fan

1#include <LiquidCrystal_I2C.h>
2
3LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows
4
5// Pin Definitions
6const int tempPin = A0;   // LM35 sensor output connected to A0
7const int fanPin = 9;     // PWM pin connected to the fan (Pin 9 supports PWM)
8
9// Variables
10int tempReading = 0;      // Variable to store the raw temperature reading
11float temperatureF = 0;   // Temperature in Fahrenheit
12int fanSpeed = 0;  
13
14void setup()
15{
16  lcd.init(); // initialize the lcd
17  lcd.backlight();
18
19 
20
21  pinMode(A0, INPUT);
22  Serial.begin(9600);
23  pinMode(fanPin, OUTPUT);
24}
25
26void loop()
27{
28  lcd.clear();
29  if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 70) {
30    lcd.clear();
31    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
32    lcd.setCursor(0, 0);
33    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
34    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
35    lcd.setCursor(0, 1);
36    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
37    lcd.setCursor(5, 0);
38    lcd.print("F");
39    lcd.setCursor(5, 1);
40    lcd.print("C");
41    lcd.setCursor(7, 0);
42    lcd.print("Fan Speed");
43    lcd.setCursor(12, 1);
44    lcd.print("PWM");
45    lcd.setCursor(8, 1);
46    lcd.print(fanSpeed);
47    fanSpeed = 155;
48    if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 80) {
49     lcd.clear();
50     Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
51     lcd.setCursor(0, 0);
52     lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
53     Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
54     lcd.setCursor(0, 1);
55     lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
56     lcd.setCursor(5, 0);
57     lcd.print("F");
58     lcd.setCursor(5, 1);
59     lcd.print("C");
60     lcd.setCursor(7, 0);
61     lcd.print("Fan Speed");
62     lcd.setCursor(12, 1);
63     lcd.print("PWM");
64     lcd.setCursor(8, 1);
65     lcd.print(fanSpeed);
66     fanSpeed = 255;
67    }
68    delay(2000); // Wait for 2000 millisecond(s)
69  } 
70  else {
71    lcd.clear();
72    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
73    lcd.setCursor(0, 0);
74    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
75    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
76    lcd.setCursor(0, 1);
77    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
78    lcd.setCursor(5, 0);
79    lcd.print("F");
80    lcd.setCursor(5, 1);
81    lcd.print("C");
82    lcd.setCursor(7, 0);
83    lcd.print("Fan Speed");
84    lcd.setCursor(12, 1);
85    lcd.print("PWM");
86    lcd.setCursor(8, 1);
87    lcd.print(fanSpeed);
88    fanSpeed = 0;
89    delay(2000); // Wait for 2000 millisecond(s)
90  }
91
92 analogWrite(fanPin, fanSpeed);
93 Serial.print("Fan Speed: ");
94 Serial.println(fanSpeed);
95
96
97}

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows

// Pin Definitions
const int tempPin = A0;   // LM35 sensor output connected to A0
const int fanPin = 9;     // PWM pin connected to the fan (Pin 9 supports PWM)

// Variables
int tempReading = 0;      // Variable to store the raw temperature reading
float temperatureF = 0;   // Temperature in Fahrenheit
int fanSpeed = 0;  

void setup()
{
  lcd.init(); // initialize the lcd
  lcd.backlight();

 

  pinMode(A0, INPUT);
  Serial.begin(9600);
  pinMode(fanPin, OUTPUT);
}

void loop()
{
  lcd.clear();
  if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 70) {
    lcd.clear();
    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 0);
    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 1);
    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(5, 0);
    lcd.print("F");
    lcd.setCursor(5, 1);
    lcd.print("C");
    lcd.setCursor(7, 0);
    lcd.print("Fan Speed");
    lcd.setCursor(12, 1);
    lcd.print("PWM");
    lcd.setCursor(8, 1);
    lcd.print(fanSpeed);
    fanSpeed = 155;
    if ((-40 + 0.878679 * (analogRead(A0) - 20)) >= 80) {
     lcd.clear();
     Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
     lcd.setCursor(0, 0);
     lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
     Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
     lcd.setCursor(0, 1);
     lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
     lcd.setCursor(5, 0);
     lcd.print("F");
     lcd.setCursor(5, 1);
     lcd.print("C");
     lcd.setCursor(7, 0);
     lcd.print("Fan Speed");
     lcd.setCursor(12, 1);
     lcd.print("PWM");
     lcd.setCursor(8, 1);
     lcd.print(fanSpeed);
     fanSpeed = 255;
    }
    delay(2000); // Wait for 2000 millisecond(s)
  } 
  else {
    lcd.clear();
    Serial.println((-40 + 0.878679 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 0);
    lcd.print((-40 + 0.878679 * (analogRead(A0) - 20)));
    Serial.println((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(0, 1);
    lcd.print((-40 + 0.488155 * (analogRead(A0) - 20)));
    lcd.setCursor(5, 0);
    lcd.print("F");
    lcd.setCursor(5, 1);
    lcd.print("C");
    lcd.setCursor(7, 0);
    lcd.print("Fan Speed");
    lcd.setCursor(12, 1);
    lcd.print("PWM");
    lcd.setCursor(8, 1);
    lcd.print(fanSpeed);
    fanSpeed = 0;
    delay(2000); // Wait for 2000 millisecond(s)
  }

 analogWrite(fanPin, fanSpeed);
 Serial.print("Fan Speed: ");
 Serial.println(fanSpeed);


}

Documentation

schematic

Brave Bigery-Robo (1).png

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