If a USB Cable is being used between two devices, are the power wires needed?

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Barlioh's picture
If a USB Cable is being used between two devices, are the power wires needed?

I am trying to figure out a way to give power to an android tablet and a DSLR camera at the same time (for a photo booth).

I was able to purchase an AC adaptor "battery" plugin for the camera, but the DSLR needs to be plugged in to the tablet via an OTG data cable (USB).

My question is; Can I open the USB cable and cut the two power cables (red and black), then wire them to a mobile device wall wart charger?

Basically, I want to open the USB cord and not cut the data cables so that the camera and tablet are still connected via data, but I want to remove the red and black wires going to the camera (so the camera does not get power). Instead, I want the power wires going from the tablet to go to AC power via a mobile device wall wart charger. will this ruin any data transfer? Does the data need to be transferred with the power for information to be sent?

I think I've over-explained enough, but please ask if I haven't made sense.

vladmaster99's picture
You would not need to do this

You would not need to do this if the Camera requires less that 250mA. That is the tablet should be able to supply the camera.

You could use a powered hub that could supply more than 250mAmps this would save trying to cut cable. If the camera is power hungry.

Or jaycar has had a usb power injection kits Which may or may not work. Some usb devices require the data lines to be connected by a resistor ie ~200 Ohm to go into charging mode Ie >250mA.. Or resistor voltage divider network (i.e. Apple). see USB Standard Charging release 1.1. If this is the case usb device can not charge the device quickly and use the usb data lines at the same time.

Some devices which can not charge and communicate at the same time are Nokia N900, Plantronics 2.4Ghz Headphones model 955.

And Many other devices.

Cheers hope this helps