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A view of the flat back side of the green circuit board, resting on a wooden surface. This side is mostly flat, showing silver through-hole solder joints and a few thick copper traces visible beneath the green solder mask. In the lower-middle section, white silkscreen text reads "3x Fan Interposer v0.1" followed by the URL "https://rya.nc/". Below that, several solder pads are labelled with their functions: the bottom left features "GND, SDA, SCL" and "GND, 3V3, RX, TX"; the bottom center is labelled "PWM, TACH, 12V, GND"; and the bottom right has pads for "12V (ALT)" and "GND". The black plastic connectors protrude outward from the top edge.

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A view of the flat back side of the green circuit board, resting on a wooden surface. This side is mostly flat, showing silver through-hole solder joints and a few thick copper traces visible beneath the green solder mask. In the lower-middle section, white silkscreen text reads "3x Fan Interposer v0.1" followed by the URL "https://rya.nc/". Below that, several solder pads are labelled with their functions: the bottom left features "GND, SDA, SCL" and "GND, 3V3, RX, TX"; the bottom center is labelled "PWM, TACH, 12V, GND"; and the bottom right has pads for "12V (ALT)" and "GND". The black plastic connectors protrude outward from the top edge.
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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