[Andrew] was getting some bad performance from a couple of USB devices he had connected with an unpowered hub. This is a issue since the hub avoids devices from negotiating with the host controller for much more current. He fixed it by adding an outside power supply to his USB hub.
In this situation the PCB already had a footprint for a power connector. The producer uses one board for a number of different models as well as just leaves the supply components unpopulated. [Andrew] managed to discover a barrel jack in his parts bin that matched the footprint.
One essential thing to do before hooking up the source is to disconnect the 5v cable from the incoming cable television from the computer. The other suggestion we can provide you is to utilize a great regulated 5v source to guarantee you don’t damage the stuff you’re trying to power. That means avoiding deals that are as well great to be true.