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I've been searching online for a USB Cable extender for a rather long distance (let's say 10 meters). I'm familiar with the notion that the longer the cable, the weaker the signal might get, more noise, increase error rate, etc.

Usually, you solve this by putting an active element in the middle. In Ethernet connections is can be an active switch, a router, etc.

Now, I'm seeing this extenders that advertise no external power source is needed because they rely on an "ASIC chipset" that "buffers" the signal.

From what I know, it doesn't make any sense to claim that you can boost a signal without adding a power source. Also, buffering AFAIK could, at best, serve to some error-correcting algorithm or something.

So... what sorcery is this? :P

Thanks!

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    \$\begingroup\$ USB cables carry power and I expect that is being used; a very low power chipset would probably not affect the power delivery to the downstream device very much. \$\endgroup\$
    – Peter Smith
    Commented Feb 15, 2017 at 14:17
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    \$\begingroup\$ I have a black box that contains a DC/DC to boost the incoming voltage up to 5.25V and then uses that on the line to the attached USB device. Works fine. \$\endgroup\$
    – PlasmaHH
    Commented Feb 15, 2017 at 14:19
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    \$\begingroup\$ It could sacrifice power for data. Thus you'd lose some current but gain signal amplification. \$\endgroup\$
    – Bort
    Commented Feb 15, 2017 at 14:20
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    \$\begingroup\$ do you know what this chipset might actually be doing It would be similar to a USB hub with only one port. You could use a USB hub and only connect one port and leave the others open. \$\endgroup\$
    – Bimpelrekkie
    Commented Feb 15, 2017 at 14:25
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    \$\begingroup\$ @jotadepicas - The power consumption of a buffer should be very very small, but it could have an impact. I imagine that it would work by using a Schmidt trigger or similar hysteresis effect, which would pull 4.9V levels back up to 5V (for example). \$\endgroup\$
    – Bort
    Commented Feb 15, 2017 at 14:27

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The advertising is a "play on words." The key term is no external power. It does use some internal power to boost the signal. In addition to the signal wires, there is also a ground and +5V wires in the USB cable.

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