An automatic cooling system that adjusts fan speed based on temperature. A sensor (LM35/DS18B20/DHT) feeds the microcontroller, which drives the fan via PWM or a relay/MOSFET. You can set temperature thresholds, add hysteresis to avoid rapid ON/OFF, and show live temperature/speed on a display. Ideal for enclosures, power supplies, 3D printers, and electronics racks.

Parts Used:

1. Microcontroller: Arduino Uno/Nano (or ESP32 for IoT)
2. Temperature Sensor: LM35 (analog) / DS18B20 (digital) / DHT11/DHT22 (temp + humidity)
3. Fan: 5–12 V DC brushless fan (80/120 mm) or blower
4. Driver & Switching: N-MOSFET (logic-level, e.g., IRLZ44N) or relay module; flyback diode
5. Power Supply: 5 V for logic; separate 12 V (typ.) for fan (common ground)
6. Display (Optional): 0.96″ OLED or 16×2 LCD for Temp/Speed
7. Input (Optional): Buttons/rotary encoder for setpoint & min/max speed
8. Buzzer/LED (Optional): Over-temperature alarm/status
9. Misc.: Heatsinks (if needed), fuse/TVS, connectors, enclosure, airflow grill