If you want to use Arduinos or similar microcontrollers on robots or drones, you'll need to interface them to the on-board battery pack(s). And since there is no such thing as a 3.3V or 5V battery, it always includes some kind of voltage regulator.
Most Arduino boards have an integrated voltage regulator, but it's a linear one and thus not very efficient at converting a high voltage to 5V, wasting precious battery power in the process. If you draw too much current, it will get extremely hot, and it is unable to support heavier loads like servo motors.
This simple power supply board tackles the problem with a buck regulator, the simplest type of switched mode DC/DC converter. It uses a single IC of type LM2596, a flyback diode, and a handful of passive components to set up an efficient voltage regulator. It accepts any DC input voltage between 5V and 30V, making it compatible with just about any battery pack out there. With a screw terminal it's very easy to connect it, and fine tune the output voltage with a trimmer.
The board has been laid out as a single sided PCB (bottom layer) with only through hole components, all of which are very easy to source. This makes it a perfect soldering exercise.
The input is fully protected against overvoltage, short circuit and reverse polarity, making it a durable and reliable partner for robotics!
Note: when sourcing the LM2596, make sure to look for the adjustable output version (LM2596-ADJ) and not the fixed voltage output ones (LM2596-5.0) etc. If you happen to have the fixed output voltage version (LM2596-5.0) you can still make the circuit work by removing the feedback voltage divider and tying the feedback input of the LM2596-ADJ directly to the output capacitor.