Arduino Fan Project

Project Overview

Automated Exhaust Fan is an Arduino-based system designed to monitor bathroom humidity and temperature, activating a fan and buzzer when levels exceed thresholds to prevent mold growth. The project integrates:

DHT11 sensor (environmental monitoring)
MOSFET transistor (fan control)
I2C LCD (real-time data display)
Piezo buzzer (audible alerts)

Key Features:

Fan triggers at high humidity/temperature
Multi-tier buzzer alerts (low/high severity)
Compact housing with concealed wiring

1. Inspiration & Problem Identification

Motivation:

My bathroom lacked ventilation, leading to moisture buildup and mold risk. Existing exhaust fans were either manual or expensive.

Initial Goal:

Create a low-cost, automated system to:

Detect humidity/temperature spikes.
Activate exhaust fan + alerts.
Display real-time data.

2. Research & Prototyping

Phase 1: Learning from Existing Work

Adapted LIMPINGLIM's Humidity-Controlled Fan (Arduino Project Hub) but expanded it with:

LCD display (SunFounder tutorials).
Buzzer (classroom experience).

The research phase involved exploring both hardware and software aspects, leveraging online resources while adding unique elements based on personal experience.

Phase 2: Hardware Hurdles

Problem: Original schematic used Arduino Nano; I had an Uno.

Solution: Redesigned circuit:

Moved DHT11 to Pin 2.
Used breadboard for 5V distribution.
Added 12V MOSFET for fan control.

Prototyping & Testing

Test 1: Initial breadboard circuit setup

Test 3: Fan activation with temperature control

Final Schematic: Revised schematic (see Fig. 3)

Final Schematic

Final schematic diagram showing component details and wiring connections

3. Iterative Development

Software Challenges:

LCD Integration:

Struggled with I2C address conflicts.
Fixed by testing 0x27 vs. 0x3F and using LiquidCrystal_I2C library.

Sensor Calibration:

Initially unreliable readings; added SimpleDHT library for stability.

Final Logic:

                                
void loop() {

  byte temp, humidity;

  dht11.read(pinDHT11, &temp, &humidity, NULL);

  lcd.print("Temp:"); lcd.print((int)temp);

  lcd.print("Hum:"); lcd.print((int)humidity);

  if (temp > 40) {

    digitalWrite(Fan, HIGH);

    tone(buzzer, 2000); // High-pitched alert

  }

}

4. Physical Assembly

Design Goals:

Minimalist housing with hidden wires.
Sensor placement near shower for accuracy.

Process:

Mockup: Cardboard prototype (Fig. 6).
Final Build:
- Air-dry clay "bathroom" facade.
- Components mounted on foam board.

Final Assembly

Front view of completed assembly

Side view showing component arrangement

Demonstration video of the working system

Figure: Final assembly

5. Testing & Validation

Fan Activation: Used a hairdryer to simulate temperature spikes (Fig. 4).
Buzzer Tones: Tested frequencies (100Hz for low, 2000Hz for high alerts).
LCD Readability: Verified under varying light conditions.

Unexpected Issue:

Debris (from clay) interfered with sensor.
Fix: cleaned the sensor.

Key Learnings

Adaptability:
- Pivoting from Nano to Uno required creative rewiring.
Debugging:
- Serial Monitor was invaluable for tracking sensor errors.
User Feedback:
- Class critiques led to adding the LCD (originally not planned).

Future Improvements

Enhanced Alerts:
- RGB LED to visually indicate humidity levels.
Energy Efficiency:
- Replace 12V fan with a 5V USB model.
Cloud Integration:
- Log data via IoT (e.g., Blynk) for long-term trends.

Conclusion

This project transformed a personal annoyance into a functional solution. It honed my skills in:

Circuit design (MOSFETs, I2C).
Sensor integration (DHT11 calibration).
Rapid prototyping (clay + cardboard).

Impact: The system now runs in my bathroom, proving its practicality.

Skills Demonstrated:

⌙ Arduino Programming | Circuit Design | Problem-Solving | User-Centered Design

Project Artifacts:

GitHub Repo | Demo Video | Full Schematic

Automated Exhaust Fan