It’s time to charge your phone or other device on a USB receptacle you don’t own, so you would rather not expose the data lines as well. DIY options vary from cutting and disconnecting the appropriate cable (I’d suggest heat shrink) to literally taping over the data contacts. Though the tape method might not be the most durable, it’s quite clever, and would work well in a pinch.
For this particular use there are commercially available USB data blocker options at market. But this is the first time I’ve seen one that has the ability to selectively switch all four of the USB lines.
The USB-Helper can switch off the data, power, and ground pins individually. For hardware developers this can come in quite handy for testing as you go. Want to share data and common ground but not the power rail? No problem. Need to test what happens if there’s a break in just one of the data lines? This dongle is for you. It’s available assembled, and even has an optional 3D-printed case.
For help with other USB hacking/modifications, Tindie has quite a few USB breakout boards, which I outline here. I’ve also gone over some of the more “Exotic” breakouts in a separate post if you need something even more interesting.