Handheld Fan Prototype - with HomeKit Integration

This model was inspired by the original model, but shared almost none of the original components.

I have tested a few design of the fan blades and found the centrifugal type provides the best static pressure thus the best airflow. The fan supports Homekit integration with a web interface, along with an optional rotary encoder that allows you to turn it on / off and control speed.

Here are the bill of additional materials:

• 6402 motor (https://www.amazon.com/dp/B00UYTFWI2) that's compact enough to fit inside.
• DRV8871 DC motor driver (https://www.amazon.com/dp/B0DN66P9XW)
• Rotary encoder / Switch (https://www.keyestudio.com/products/free-shipping-keyestudio-rotary-rotation-encoder-module-for-arduino) - this is optional if you want manual control
• Raspberry Pi Pico W (or Raspberry Pi Pico 2 W, or Raspberry Pi Pico)
• Buck converter to power the Pi
• 7.2V (twin-pack) 18650 battery

Here is the code that you'll need to program the Pi: sqexpress/pico_fan: This is for a desk fan that's runs on Raspberry Pi Pico W and works with Apple Homekit The wiring diagram is detailed on the github link as well.

Please note that this prototype still has limited airflow and pretty loud due to the size of the fan blade - I have tested a bigger desktop version (you may use the exact same components, but you'll need to redesign the airducts, fan blades and motor mount) that can provide much better airflow at much lower noise level.