Provide more information, including the model number of your NUC, and explain "output 12 turns"
I needed to power a USB adapter with 3 serial ports. For that I need to have a 12V cable to connect
There's no capability to drive a connector like that (no 12V output anywhere).
I would think that an adapter providing nothing more than three serial ports would be able to run off the power supplied by a USB port. The BE NUC is equipped with multiple Blue USB 3.1 Gen2 ports that provide 900mA (4.5W@5V), a (front panel) Orange USB 3.1 Gen2 charging port that provides 1.5A (7.5W@5V) and a (back panel) USB 3.1 Gen2 USB-C port that provides 3A (15W@5V).