This is a very compact DC-DC step-down converter capable of supplying any voltage between 1.3 and 35 V from a higher voltage power supply (up to 40 V). It solves the problem of supplying commonly available 12 V computer fans from the same 24 V supply as the stepper motor drivers, and it can also be used to power 5 V or 3.3 V electronics from the motor power supply (you will need one unit for each voltage you require). The adjustment is via a precise multi-turn trimpot. The converter IC is rated 3 A, but that can not be achieved without additional cooling (e.g. a heatsink). To be on the safe side, use it for up to 1.5 or 2 A.
Please note this DC-DC converter does not offer galvanic isolation. The ground of the input and output is common. Soldering is required to attach the input and output wires.
The model currently in stock is slightly different in appearance (blue PCB, and an improved layout for better power dissipation; also, the fixing holes are in a different position).