Most devices these days are powered or recharged over USB, and that includes maker-focused devices like microcontroller development boards and single-board computers. Generally, that’s because most of us have convenient access to USB ports, and because it removes the need for a specialized power supply. But, when you’ve got a lot of devices your work area can get very cluttered with chargers, which is why Dr. Scott M. Baker built a custom USB power distribution system.
USB is designed to provide 5V of power, and your typical USB wall wart charger tops out at around 1A of current. If you’ve got a handful of devices that need simultaneous power, that can add up to a lot of watts — more than a simple USB hub can provide. More importantly, some devices need a nice, clean power source, and cheap USB wall wart chargers often supply pretty questionable power. That’s not a big deal for devices with built-in over-current and over-voltage protection, like your smartphone, but could damage sensitive equipment.
To build something better, Baker started with a commercial 12V 5A power supply like you’d get with your laptop. That provides a total of 60 watts — enough to power 12 typical 1A devices. The power from that is then pushed through an ACT4533A switching regulator to bring it down to 5V. That regulator also features integrated over-current and over-voltage protection, so sensitive devices are safe. The regulator is built into a custom PCB, and multiple PCBs can be chained together to provide a multitude of USB ports with high-quality power. Finally, Baker put those and an inexpensive watt meter into 3D-printed cases for his bench.