Arduino Fan Controller

This project is an Arduino-based fan controller that allows you to adjust the speed of a 4-pin PWM fan using a push button. It also measures and displays the fan's RPM via the serial monitor.

Features

• PWM control of a 4-pin fan
• RPM measurement using the fan's tachometer output
• Speed adjustment in 10% increments via a push button
• Serial output of current speed and RPM

Hardware Requirements

• Arduino board (Uno, Nano, etc.)
• 4-pin PWM fan
• NPN transistor (for PWM control)
• Push button
• Resistors (as needed for button and transistor)
• Wires and breadboard

Pin Configuration

• pwmPin (9): PWM output to transistor base
• tachPin (2): Tachometer input from fan
• buttonPin (7): Push button input

How It Works

• The fan speed is controlled by PWM signal on pin 9.
• The push button on pin 7 increases the speed by 10% each press, cycling from 0% to 100%.
• The tachometer signal from the fan is read on pin 2 using an interrupt to count pulses.
• Every second, the RPM is calculated and printed to the serial monitor along with the current speed percentage.

Usage

1. Connect the hardware as described above.
2. Upload the ArduinoFanController.ino sketch to your Arduino.
3. Open the serial monitor at 9600 baud to view speed and RPM.
4. Press the button to increase fan speed in steps.

Schematic

Below is a simple schematic for connecting the components (updated for a 5V fan, 1kΩ resistor, and two capacitors in parallel to the fan):

				 +5V (Fan Power)
						 |
					 [Fan]
						 |
				 +---+---+
				 |   |   |
				 |   |   +-- PWM (Pin 9, Arduino) via 1kΩ resistor
				 |   +------ Tach (Pin 2, Arduino)
				 |
				GND
				 |
			[C1] 100uF Electrolytic
			[C2] 104pF Ceramic
			(C1 and C2 in parallel to the fan)

	 [Button]
		 |
	 Pin 7 (Arduino)
		 |
		GND

	 [NPN Transistor]
	 Collector: Fan GND
	 Base: PWM (Pin 9, Arduino) via 1kΩ resistor
	 Emitter: Arduino GND

Notes:

• The fan is powered by 5V.
• A 1kΩ resistor is used between Arduino pin 9 (PWM) and the transistor base.
• Two capacitors (100uF electrolytic and 104pF ceramic) are connected in parallel to the fan for noise filtering and stability.
• The tachometer wire goes directly to Arduino pin 2.
• The button is connected between pin 7 and ground, with a pull-up resistor enabled in code.

Notes

• The RPM calculation assumes the fan generates 2 pulses per revolution.
• You can modify the code to set the speed via serial input (see commented section in the code).

License

This project is open source and free to use for personal and educational purposes.