[kwlug-disc] USB 2.0 hubs, and power ...

Andrew Kohlsmith (mailing lists account) aklists at mixdown.ca
Tue Oct 29 21:41:26 EDT 2019


> On Oct 29, 2019, at 9:36 PM, Khalid Baheyeldin <kb at 2bits.com> wrote:
> I used the "USB Safety Tester" dongle, and when the camera is taking images, it only registers at 0.04A, so 40mA, well within the range of any unpowered USB 2.0 hub.
> Yes, I hear ya all about how the cables are what matters, and I will have to experiment with a few.

If that truly is the current draw when operating then there is no way even a long, crappy extension cable will cause enough voltage drop to cause any issues. 200mW is a pretty low-power device and you’d have to have a cable with a resistance in the area of 6 ohms to drop the USB voltage by 5%.

-A.





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