Temperature Based Fan Speed Control And Monitoring Using Arduino

This project offers a stand-alone, automated fan speed controller that intelligently adjusts fan speed in response to temperature changes. Using embedded technology, this closed-loop system offers efficient and dependable temperature control. The Arduino board’s microcontroller (MCU) ATMega8/168/328 allows for rapid, dynamic control, and the LCD screen gives real-time temperature and fan speed data for convenient monitoring.

This project demonstrates a self-sufficient fan speed controller that smartly adjusts to temperature variations. It uses embedded technologies to provide effective and dependable temperature regulation. The Arduino’s strong microprocessor allows for quick modifications, and the LCD screen displays real-time feedback for convenient monitoring.

Circuit and Working:

Circuit diagram of the temperature fan speed control and monitoring is shown in Fig. 1. It is built around Arduino Uno board (Board1), 16×2 LCD (LCD1), temperature sensor LM35 (IC1) and a few other components.

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Arduino is at the heart of the circuit as it controls all functions. LM35 is a precision integrated circuit whose output voltage is linearly proportional to Celsius (Centigrade) temperature. It is rated to operate over a -55°C to 150°C temperature range. It has +10.0mV/Celsius linear-scale factor.

Temperature sensor LM35 senses the temperature and converts it into an electrical (analogue) signal, which is applied to the MCU through an analogue-to-digital converter (ADC). The analogue signal is converted into digital format by the ADC. Sensed values of the temperature and speed of the fan are displayed on the LCD. Temperature and monitoring using Arduino The MCU on Arduino drive the motor driver to control fan speed.

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Fan Speed Control Technique:

1. Pulse-Width Modulation (PWM): PWM regulates fan speed using a low-frequency signal (~30Hz) with varying duty cycle. The PWM signal controls how much power the fan receives, allowing for smoother adjustments.
2. Efficient Power Use: A small pass transistor serves as a switch, conserving power while controlling speed. However, due to the pulsed nature of PWM signals, which causes mechanical vibrations, this method may cause the fan to become slightly noisy.

Construction and Testing:

A single-side PCB for the temperature-based fan speed control and monitoring circuit is shown in Fig. 3 and its component layout in Fig. 4. Assemble the circuit on the PCB.

CON2 and CON3 are used to connect Board1 (Arduino UNO board) through external connectors. A 12V battery is used to drive the 12V DC-operated fan.

Download PCB and Component Layout PDFs: click here

Software and Programming:

Software for the automatic temperature controller and monitor circuit is written in Arduino programming language. Arduino Uno is programmed using Arduino IDE software.

ATmega328P on Arduino Uno comes with a pre-programmed bootloader that allows users to upload a new code to it without using an external hardware programmer.

Connect Arduino board to the PC and select the correct COM port in Arduino IDE. Compile the program (sketch). Then select the correct board from Tools Board menu in Arduino IDE and upload the sketch (abfc.ino) to Arduino through standard USB port.

Advanced Features and Customization Options: 

1. Multiple Fan Control: Use this arrangement to control numerous fans based on temperature zones inside a room.
2. Real-Time Data Logging: Connect to an SD card module or IoT platform to record temperature and speed data over time for study.
3. Enhanced Control Algorithms: Use proportional-integral-derivative (PID) control to provide smoother, more exact adjustments in response to temperature fluctuations.
4. Noise Reduction: Use capacitors or inductors in the PWM circuit to reduce noise from fan vibrations.

Download the source code: click here

Biswajit Das was manager – R&D, EFY Labs till recently.

This article was first published on 16 December 2016 and was updated on 28 October 2024.