Core Components:

• HEPA Filter: Removes 99.97% of particles ≥0.3µm (dust, pollen, mold).
• Activated Carbon Filter: Adsorbs odors, VOCs, and gases.
• Fan Motor: DC brushless for efficiency and low noise (e.g., 12V/24V).
• Sensors: PM2.5 laser sensor, humidity/temperature (e.g., SHT30), optional VOC sensor.
• Control Board: MCU (e.g., ESP32) for fan speed, sensor readout, UI, and Wi-Fi.
• Power Supply: 100-240V AC to 12V/24V DC adapter.

Circuit Notes:

• Use optocouplers or relays for safe MCU-to-fan isolation.
• Implement overcurrent protection on motor lines.
• Add EMI filter on AC input for compliance.

Optional Features:

• UV-C LED (265nm) for germicidal action (ensure no ozone emission).
• Ionizer (with ozone level monitoring per safety standards).
• OLED display or LED indicators for air quality.

Design Tips:

• Ensure low airflow resistance with proper duct design.
• Thermally protect motor and power components.
• Calibrate sensors in controlled environments.