USB Ground referencing

[codycode]

So I decided that I wanted to make a powered USB cable.

The layout goes something like this; Wallwart USB charger -> VCC, GND -> Female USB <- D+,D-,GND <- Laptop

So my laptop's ground will be referenced to the charger's ground, or in other words I'm referencing the grounds of 2 USB busses together.

I just wanted to make sure that this would not cause some sort of ground loop, or power contention. So does this should potentially harmful, or should this work just fine?

[stmdude]

I can't figure out how you want to wire this thing up. Maybe a picture would help us understand?

If it helps, the "ground" on USB Wall chargers is floating, so it'll adapt to whatever ground-potential your laptop has.

[T3sl4co1l]

This is one reason why PSUs have isolated outputs.

If your USB charger does not have isolation... send it back 

Tim

[Michaelbradford]

Check out bigclive.com on you tube he does a lot of USB stuff msg him he quite good