Re: USB powered lamp?

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They may, but there are a lot of them on the shelves in the stores.

"Robert Marquardt" <robert_marquardt@xxxxxx> wrote in message
news:O4xPWBSBGHA.2692@xxxxxxxxxxxxxxxxxxxxxxx
> David J. Craig wrote:
>
>> The big limit is that you can only assume 100ma unless you know it is a
>> powered hub and then your limit is 0.5A. How bright can a light be with
>> 5V 0.5A? Led only? Halogen - doubt it. Is 5V at 0.5A a total of 25w or
>> 2.5w? I don't pretend to be an EE, so I forget the formula, but I thought
>> it was V * A = W. Night lights are usually 4w and you can't read with
>> those.
>
> All the calculation is wrong because the power lines are part of
> the bus protocol. Such a device violates the USB spec.


.

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