How to Use 12v PWM Fan (120mm): Examples, Pinouts, and Specs

The 12V PWM Fan (120mm) is a versatile cooling solution designed to operate on a 12-volt power supply. It utilizes Pulse Width Modulation (PWM) for precise speed control, making it ideal for a variety of applications. This fan is commonly used in electronic devices, computer systems, and other environments where efficient cooling is essential.

To use the 12V PWM Fan in a circuit, follow these steps:

1. Power Supply Connection: Connect the +12V pin to a 12V DC power supply and the GND pin to the ground.
2. PWM Signal: Connect the PWM pin to a PWM-capable output pin on your microcontroller (e.g., Arduino UNO).
3. Tachometer Feedback: Optionally, connect the Sense pin to an input pin on your microcontroller to monitor the fan speed.

• PWM Signal: Ensure the PWM signal is within the specified frequency range (25kHz) for optimal performance.
• Power Supply: Use a stable 12V DC power supply to avoid fluctuations that could affect fan performance.
• Mounting: Securely mount the fan to prevent vibrations and noise.
• Airflow Direction: Ensure the fan is oriented correctly to direct airflow where needed.

// Example code to control a 12V PWM Fan with Arduino UNO

const int pwmPin = 9; // PWM pin connected to the fan's PWM input
const int sensePin = 2; // Sense pin connected to the fan's tachometer output

void setup() {
  pinMode(pwmPin, OUTPUT); // Set the PWM pin as an output
  pinMode(sensePin, INPUT); // Set the Sense pin as an input
  Serial.begin(9600); // Initialize serial communication for monitoring
}

void loop() {
  int fanSpeed = 128; // Set fan speed (0-255)
  analogWrite(pwmPin, fanSpeed); // Write PWM signal to control fan speed

  // Read and print the fan's RPM (optional)
  int rpm = readFanRPM();
  Serial.print("Fan RPM: ");
  Serial.println(rpm);

  delay(1000); // Wait for 1 second
}

int readFanRPM() {
  // Function to read the fan's RPM from the Sense pin
  // This is a placeholder function and may need to be adjusted
  // based on the specific fan and microcontroller used.
  int rpm = pulseIn(sensePin, HIGH) * 60 / 2; // Calculate RPM
  return rpm;
}

1. Fan Not Spinning:

   • Solution: Check the power supply connection and ensure it is providing 12V DC. Verify the ground connection.

2. Fan Speed Not Changing:

   • Solution: Ensure the PWM signal is within the specified frequency range (25kHz). Check the PWM pin connection.

3. High Noise Levels:

   • Solution: Ensure the fan is securely mounted to reduce vibrations. Check for any obstructions in the airflow path.

4. Incorrect RPM Readings:

   • Solution: Verify the Sense pin connection. Adjust the RPM calculation method in the code if necessary.

• Double-Check Connections: Ensure all connections are secure and correctly oriented.
• Use a Stable Power Supply: Fluctuations in the power supply can affect fan performance.
• Monitor PWM Signal: Use an oscilloscope to verify the PWM signal if the fan speed is not responding as expected.
• Consult the Datasheet: Refer to the fan's datasheet for specific details and troubleshooting tips.

By following this documentation, users can effectively integrate and utilize the 12V PWM Fan (120mm) in their projects, ensuring optimal cooling performance and reliability.