DC to DC conversion has come a long way. What was once took an electromechanical vibrator and transformer has been reduced to a PC board the size of a largish postage stamp that can be had for a couple of bucks on eBay. So why roll your own buck-boost converter for the ground up? Maybe because sometimes the best way to learn is by doing.
When it comes to clear and succinct explanations, [GreatScott!] has you covered. We recently reported on one of the videos from his Electronic Basics series, but the video below covers the slightly more advanced topic of DC-DC conversion in depth. [GreatScott!] describes how buck converters and boost converters work as separate entities, and how they can be integrated into a non-inverting buck-boost converter. He further simplifies that circuit into an inverting buck-boost, and sets about explaining the limitations of the circuit. With the addition of an op amp to provide feedback to control the duty cycle of the ATtiny85, the buck-boost overcomes its limitations and keeps a solid set point regardless of load or supply voltage.
If you’re looking to get into the theory of DC-DC conversion by putting it into practice, this is a great project to get you started. It’s also a good review for the old hands, as are most of [GreatScott!]’s videos. They’re worth checking out.