Catalogue

An adjustable step-down regulator on a small board — feed it a higher DC voltage, turn the trimmer, get a lower one out. This is how you run 5 V logic off a 12 V battery without cooking a linear regulator. Set the output before you connect anything to it: power the input, turn the trimmer while watching a meter on the output, then wire up your load. The trimmer is multi-turn, so it takes several rotations to move — that is normal, not a fault.