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The Guardian - UK
The Guardian - UK
Technology
Jack Schofield

Powered USB?

I'm considering buying a USB hub. Is it necessary for it to have an independent power source? Bob Tucker

It's not, strictly speaking, necessary to have a powered USB hub, but I'd definitely recommend it. One of the problems with USB is that a device is only allowed to draw up to 500mA of power (100mA on first connection). So, if you buy a non-powered hub, it will only support one high-power (500mA) peripheral, and the other ports on that hub may be useless. What you have bought is, in effect, a high-priced USB extender cable. Plug a mixture of devices into a non-powered hub and some might work while others might not, and you probably won't get much help from Windows as to why they aren't working. Since people expect to be able to plug any USB device into any USB port, I think this is really bad. Using a powered USB hub generally eliminates the problem.

Comment: This item is being considered for publication: additions and improvements welcome!

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