External drive with unusual USB Cable

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Cleverbum - 22 Jan 2007 09:32 GMT

I've just bought a new USB2.0 external hard disk and it came with a
rather odd USB cable and no manual.
The cable is a USB 'a'-'mini b' cable, but has two 'A' heads does
anyone know how it's intended to be used? is this so two computers can
share the drive? or will it double my data rate?

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Paul - 22 Jan 2007 11:37 GMT

> I've just bought a new USB2.0 external hard disk and it came with a
> rather odd USB cable and no manual.
> The cable is a USB 'a'-'mini b' cable, but has two 'A' heads does
> anyone know how it's intended to be used? is this so two computers can
> share the drive? or will it double my data rate?

Look carefully at the connectors.

One connector should be using all four pins (+5V, D+, D-, GND).

The second connector only has power (+5V, GND).

By connecting both connectors to the same computer, you
get 500mA of current from the first connector, 500mA
of current from the second connector, giving a total
of 1000mA or 1 Amp of current.

Many tiny disk drives have a 5V @ 1A power spec.

So the two cables should be connected to the same computer,
in order for the drive to get the current it needs. The
connectors are *not* a sharing scheme.

Paul

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Cleverbum - 25 Jan 2007 08:57 GMT

> > I've just bought a new USB2.0 external hard disk and it came with a
> > rather odd USB cable and no manual.
[quoted text clipped - 18 lines]
>
> Paul

Both plugs have all the pins in, though I don't know which actually
have wires connected to the pins. I'll plug it in and see how it goes
though, thanks.
Martin

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Loren Pechtel - 28 Jan 2007 02:19 GMT

>I've just bought a new USB2.0 external hard disk and it came with a
>rather odd USB cable and no manual.
>The cable is a USB 'a'-'mini b' cable, but has two 'A' heads does
>anyone know how it's intended to be used? is this so two computers can
>share the drive? or will it double my data rate?

That is to run a USB-powered 2.5" enclosure. You plug both USB
connectors in first, then plug the other one into the enclosure. In
reality only one of those two connectors actually works as a USB, the
other is simply to obtain power.

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