I’ve started to accumulate many devices and tools that use 5V power sources, typically a USB-style cable with either a micro-usb plug or a barrel plug at the other end. In addition to my typical chargeable handheld devices like my iphone and ipad and my kindle and my fitbit, there’s my Eakins inspection camera / microscope and various raspberry pi projects. Rather than get out a separate wall-wart or use my benchtop variable supply, for many projects it is handy to just plug in to a USB bus.

My goals include:

1. The ability to switch each device on/off with a rocker or toggle switch
2. Current limiting capability via a fuse or similar device
3. Overvoltage protection
4. Visual indicator (LED) of operational status
5. Multiple independent outlet

Goal #5 is the one that’s difficult to find a commercial product. I was easily able to find several consumer grade strip-like USB3 hubs that had individual switches and LEDs. However, they all shared a common power bus. One device that generated noise could affect the other devices. In the worst case, a grossly misbehaving device, like a rogue nixie tube project, could malfunction and introduce harmful power to the rest of the bus. In a benchtop situation where expensive equipment is used together with delicate prototypes, isolation seems critical.

Unable to find a solution, I built my own.”


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