This is a multi-part message in MIME format. ------=_NextPart_000_0000_01C4C729.88669FB0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit FYI: ---- A recent thread inspired me to whip up this chart -- hopefully it will be useful to others as well. The voltage drops listed in the chart should be 'maximum' as the USB 2.0 specification listed the conductor resistance value ("ohms per 100 meter") for various wire gauges as 'maximum' -- I'm not sure exactly what the upper temperature range is on these values (higher resistance), but I'm assuming it is detailed in the 'ASTM-D-4566 Section 13' that the USB 2.0 specification refers to. As you can see from the chart, buying USB cables with a 20 AWG power pair can reduce your power pair voltage losses at a given length versus other AWG gauge options. I'm glad that USB cable manufacturers allow the USB end-users to choose the power pair gauge wire that he/she wants and/or needs. This has been helpful to me in the past when I needed to extend the distance of my 2.5 inch portable hard drive unit from my PC. When I bought the first cable, I was not aware at the time that USB cables came with various power pair wire gauge sizes -- the drive did not work because of the excessive I2R losses, but buying a cable with a lower gauge number solved the problem, and the drive has been working great an reliably for years -- totally USB powered. :) L-Com (www.L-Com.com) in Andover, Massachusetts USA is only one example of a manufacturer who sells USB 2.0-compliant cables that use 20 AWG for the power pair (in lengths of 0.5, 1.0, 2.0, 3.0, and 5.0 meters in length). (And before people jump on me for appearing to come across as USA-centric: Yes, I realize that this list is world-wide and there is a world outside the USA -- I'm a member of the human race first before I'm a United States of America citizen. I'm just mentioning this company since it is close to me, so please don't read anymore into it than that, ok? :) ) Best regards, Ken Pergola P.S. I also have the chart in PDF format, but unfortunately, even after zipping it up, it still exceeds the file size upload limit. 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