We’re quite sure that all hobbyists have used the 7805 voltage regulator at least once in their lives. They are a simple way to regulate 7V+ voltages to the 5V that some of our low power ...
The 78XX series of regulators ... voltage coming in. But the more voltage you put in, the more the part is going to dump out as heat. So running from 9V is going to be cooler than running from 24V.