0Jack A Lopez 11 months ago I think it is a DC-to-DC converter, specifically a buck converter, built around the LM2596 IC (integrated circuit). https://www.alldatasheet.com/view.jsp?Searchword=L...It's purpose is to convert DC power, at voltage Vin, to DC power at a lower voltage Vout. That is: Vout < Vin. Also the one in your picture is adjustable. The little screw on that pot can be turned, to adjust the set point for Vout.Actually that is sort of what the word "buck" means in this context. It means Vout less than Vin. Sometimes the phrase "step down" is used as a synonym.https://en.wikipedia.org/wiki/Buck_converterI suppose the antonym to "buck" is "boost" or "step up." That is the other, sort of commonly seen switching topology.https://en.wikipedia.org/wiki/Boost_converterAlthough those two are not exhaustive. Other kinds of switching converters exist. Buck and Boost are just the two most often seen.The buck converter is more efficient than the, uh, sort of old school way, a linear voltage regulator IC (the like LM317, or LM78xx series of voltage regulators) to get a lower DC voltage from a higher one.https://en.wikipedia.org/wiki/Linear_regulatorHowever, the higher efficiency of the buck converter comes at the cost of higher complexity. A whole board is needed, instead of just one little printed silicon IC. It needs a physical way to store energy, temporarily. Usually a big inductor is used. And it needs a way to alternately move energy into, and out of, the energy storage.In contrast, the linear regulator simply disposes of voltage as heat. A linear regulator necessarily wastes an amount of power equal to:Pwaste = I*(Vin-Vout) where I=Iin=IoutAs far as I know there is no linear regulator analog to the boost converter (with Vout>Vin), and the reason why is because it would involve some impossible physics, like negative power dissipation (Pwaste<0), essentially a black brick that gets cold instead of hot, by mysteriously absorbing heat from its surroundings, and turning that heat into useful work.