OpenFAN Micro Automatically Powers 12V or 5V Fans From USB

Perhaps you have a passively cooled PC or two lying around generating heat, or maybe a media cabinet that gets warmer than ideal on occasion. While such conditions are generally fine, what if you’d like your equipment to run at lower temperatures without hooking up a fan that runs constantly via an external power source?

For an easy way to control both 12V and 5V cooling fans over USB, Sasa Karanovic designed the ESP32-powered OpenFAN Micro. The OpenFAN Micro features a USB-C connection, allowing it to be powered by the thing that it’s cooling, or via an external supply as needed.

Two voltage regulators provide 3.3V to the ESP32 chip, as well as 12V (as needed) for the fan itself. 5V fan power is simply passed through from the USB supply. No Power Delivery spec is required, just a normal USB connection (whatever that means these days).

For control, the ESP32 chip generates a browser-based interface. After configuring it for your local Wi-Fi network, you can log on and modify the PWM fan speed, whether it outputs 5V or 12V, and even the device’s name. Perhaps even more interestingly, a web API lets third-party scripts and automations control the board automatically, enabling other devices to request cooling.

More specifics on the design are available on GitHub, and you can buy the OpenFAN Micro on Kanovic’s shop. Of course, if you just need to control a fan via logic-level outputs, i.e. a Raspberry Pi or similar, you might also consider my EZ Fan 2 board. Having grown up in Florida, keeping things cool has been something of a lifelong pursuit for me!