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Is it possible to disconnect the 5v+ and the ground wires from a USB cable (leaving the D+ and D-) and connect them to an external 5v power source (ex a filtered regulated battery) and have the USB device and computer function properly?

I want to try to provide a cleaner power source to the USB device than what the PC would without trying to filter the PCs 5v power from its USB port.

If this would not function properly or cause damage, can someone explain why this would happen?

Thanks.

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  • \$\begingroup\$ Yes it is. But note that the shield comnection is important. \$\endgroup\$ – Rohat Kılıç Jan 6 '17 at 3:34
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    \$\begingroup\$ @RohatKılıç, This seems to be a classic "X-Y" question, a jump to conclusion. Nothing is clear in this case, how the shiled is managed, how the ground is managed, why VBUS can't be filtered just as any other power supply. \$\endgroup\$ – Ale..chenski Jan 6 '17 at 5:01
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Is it possible to disconnect the 5v+ and the ground wires from a USB cable (leaving the D+ and D-) and connect them to an external 5v power source (ex a filtered regulated battery) and have the USB device and computer function properly?

No.

It is possible to disconnect just the 5V though. Disconnecting the common ground will make communication very difficult.

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  • \$\begingroup\$ I am dealing with radio equipment and when using a laptop when the AC power is applied the noise from the power supply increase the noise on the radio software, when the AC is removed the noise is also reduced. I thought I could decouple the power source and attempt to provide something cleaner that wouldn't depend on if the AC is plugged in or not. \$\endgroup\$ – randy newfield Jan 6 '17 at 3:40
  • \$\begingroup\$ Ah, good old ground loops and mains hum. \$\endgroup\$ – Passerby Jan 6 '17 at 3:58
  • \$\begingroup\$ Anyway to try to combat this? I currently made a PCB that takes the 5v power source from the PC and throws it through a LC filter and then allows my devices tap into it and it seems to work fine (data lines are connected directly to the device). Was just wondering if I could do anything better. \$\endgroup\$ – randy newfield Jan 6 '17 at 4:09
  • \$\begingroup\$ Personally, no. But that's a whole 'nother question to this one. There may be a few questions on how to decouple or filter supply noise on usb. If not, a properly phrased question asking that would be better. \$\endgroup\$ – Passerby Jan 6 '17 at 4:11
  • \$\begingroup\$ Okay thanks for the tip I will try again tomorrow with a properly phrased question. \$\endgroup\$ – randy newfield Jan 6 '17 at 4:16

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