OT: What's in a USB cable?

[Phil]

Hi Iain

I've had similar problems myself. When my laptop has an unterminated USB cable plugged into it, the USB "ding" indicator sometimes stutters as though it thinks that a device is being rapidly and randomly connected and disconnected, and it seems to divert all its system resources to trying to recognize the newly 'attached' device, which causes the computer to similarly stutter. I have always assumed that this is just noise pick-up from the (unterminated) cable.

Phil M1GWZ



On 6 Jan 2013, at 00:10, Iain McFadyen wrote:

> I have a Standard USB-A to Micro USB-B cable, with a Blackberry logo stamped on the Micro-B end.
> 
> I use this cable for various purposes from time to time: recharging a dumb cellphone, recharging an FRS radio, and syncing/charging a Blackberry Curve to the Blackberry desktop software package.
> 
> When I leave this cable plugged in to a PC port, but with nothing plugged in to the Micro-B end, my PC plays up. The cursor hesitates as I drag the mouse across the screen. 
> 
> The problem disappears when the Standard end of the cable is unplugged from the PC.
> 
> Question: Is there any active or passive component embedded in this cable? I see no reason for any components, the VBUS, D+ D- and GND pins should be wired pin-for pin, and the ID pin at the Micro end should be open, right?
> 
> Your thoughts please...
> 
> Iain KI4HLV
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