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A top-down view of a small, rectangular green printed circuit board (PCB) resting on a light wooden surface. At the top edge are several white plastic JST-style connectors and a black four-pin header labelled "GND, 3V3, RX, TX". A large, rectangular surface-mount IC marked "AVR64DD28" takes up a lot of the board in the middle. Towards the upper right surface mount linear voltage regulator. The lower half of the board features three identical, repeating circuit layouts arranged side-by-side. Each of these three circuits contains a large surface-mount MOSFET (labelled Q11, Q21, and Q31), a diode (D11, D21, D31), a smaller transistor, and several tiny SMD resistors and capacitors. Along the bottom edge are three black four-pin PWM fan socket headers with exposed pins pointing down.

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A top-down view of a small, rectangular green printed circuit board (PCB) resting on a light wooden surface. At the top edge are several white plastic JST-style connectors and a black four-pin header labelled "GND, 3V3, RX, TX". A large, rectangular surface-mount IC marked "AVR64DD28" takes up a lot of the board in the middle. Towards the upper right surface mount linear voltage regulator. The lower half of the board features three identical, repeating circuit layouts arranged side-by-side. Each of these three circuits contains a large surface-mount MOSFET (labelled Q11, Q21, and Q31), a diode (D11, D21, D31), a smaller transistor, and several tiny SMD resistors and capacitors. Along the bottom edge are three black four-pin PWM fan socket headers with exposed pins pointing down.
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Ryan Castellucci (they/them) :nonbinary_flag: (ryanc@infosec.exchange)'s status on Thursday, 23-Jul-2026 05:05:08 JST Ryan Castellucci (they/them) :nonbinary_flag:

I got one of my fan controllers (I need two) put together.
Its purpose is to connect to a motherboard PWM fan socket and then control up to three separate PWM fans, with I2C for configuration, control, and telemetry, along with serial for debugging.
Have not yet powered it on, anyone want to tell me what I messed up before I let the magic smoke out?
I also still need to write the code for it, lol.
The unpopulated resistor footprints at the top are I2C pull-ups, which I shouldn't need, but can add if I do.

In conversation about a day ago from infosec.exchange permalink