USB cable with two connectors

**Spacecadet** · 5 July 2011, 13:58

Originally posted by xoggoth View Post

Got a Core backup device recently which has no instructions. Not really necessary as you just plug it in and it works but the USB plug has another USB cable coming off it. What's that for exactly when you get two USB plugs on one device?

Just curious really. Cheers.

one is for data and power
the other provides an extra bit of power to the external device

Plug the wrong one in and it looks like what ever you're trying to use is f**ked

**xoggoth** · 5 July 2011, 17:41

it looks like what ever you're trying to use is f**ked

Indeed, it doesn't seem to work if you just plug in the 2nd extension.

**xoggoth** · 6 July 2011, 09:07

Cheers all. I was thinking it was so could stick them together in a chain or summit, drives D:, E: etc, that would be handy.

**Clippy** · 6 July 2011, 10:51

Originally posted by zeitghost

Presumably to get around the 500mA current limit on USB.

Probably cheaper for the manufacturer to include such a USB cable than an external power adapter.

**PAH** · 6 July 2011, 13:27

In my experience, it's in case the device you connect it to isn't outputting enough juice per USB port, so you need two connections to provide enough power.

I think the only time I've had to use the second connector is with an old-ish laptop, so maybe they upped the power ceiling sometime after USB2, as I'm pretty sure it wasn't USB1. I'd have noticed it taking all week to copy a few gigs!

**Sysman** · 6 July 2011, 13:38

Originally posted by PAH View Post

I think the only time I've had to use the second connector is with an old-ish laptop, so maybe they upped the power ceiling sometime after USB2, as I'm pretty sure it wasn't USB1. I'd have noticed it taking all week to copy a few gigs!

I tried that a couple of months ago. I couldn't be bothered unpacking my laptop so used the old laptop (USB-1) to do some large downloads and started copying them to a USB drive...

I unpacked my laptop after all.

**Clippy** · 7 July 2011, 15:16

Slight tangent, but I see Intel are now moving into the USB space with their new competing connectivity solution Thunderbolt.

**PinkPoshRat** · 7 July 2011, 18:43

Just out of curiosity, does anyone else suffer from the same problem as me.... The USB plug is ALWAYS upside down when you try to plug it in....

Drives me mad, everytime

**Sysman** · 7 July 2011, 18:58

Originally posted by PinkPoshRat View Post

Just out of curiosity, does anyone else suffer from the same problem as me.... The USB plug is ALWAYS upside down when you try to plug it in....

Drives me mad, everytime

This is a manifestation of the Murphy's Law which states that any given cable will naturally orientate itself by 180 degrees to the receiving connector.

USB cable with two connectors