[Tfug] Connectors

[Bexley Hall]

Hi,

--- On Sun, 7/13/08, eric christian <ericdanc at alice-dsl.net> wrote:

> >> > Oh boy, I know this problem. For allmost all
> my USB
> >> > connectors (they're 
> >> > in the back, waaaay back) I've got cheap
> extension
> >> > cables to the front.
> >
> > I think you can only use "extension cables"
> > on USB 1.1 speeds.  I'm pretty sure you need an
> > *active* cable to support USB 2.0 speeds.  :<
>
> I looked in the MB broshure, they're 2.0.

The *cables* may be "USB 2.0".  I was commenting
that the use of *an* extension cable may not make
USB2 *speeds* available over that medium.

I.e., I think at 480Mbps there isn't much tolerance
for impedance bumps along the medium (but, I'm not
an expert on this so YMMV!  :> )

> I'm not quite sure why you use quotation marks,

Because I was *quoting* your comment  :>  I.e., *you*
called them "extension cables"...

> but the extension cables cost only  about 2 euro, and 
> are definitely a blessing: i plug in a 500 G HD or printer 
> or mem stick  or whatever *in front*, no crawling behind (under)
> the PC blind in the dark.

Yes.  I have an active cable velcro'ed to the underside of my
primary work area.  It's at just the right height to plug a
thumb drive (the most commonly plugged/unplugged device that
I use).  And, since it is only fastened with velcro, I can
easily remove it (temporarily) when I need to run a USB cable
over to some other peripheral on my desktop.

> I could even plug in a multi USB-port adaptor, i suppose.  
> This USB is a good deal. I remember i used to have to have
> a special rack in the shack just for all sorts of cables and
> plugs/jacks, and often had to get out the solder iron for this
> or that "standard" cable.

Yes.  I "solved" that to some extent by standardizing on
male-female "extension cables" (straight through wiring)
augmented by little "widgets" that had all of the customization
embedded in them.

E.g., 25 pin cables are common.  So, I have a set of long
M-F 25 pin "extension cables".  If I need a M-M (straight through)
cable, I plug a M-M widget onto the F end of the extension
cable and now I have a long M-M cable.  If I need a F-F cable,
I plug a F-F widget onto the M end of the cable.  If I need a
null modem cable, I plug a null modem widget, etc.

So, I can store 30 or 40 "specialty" cables in a small shoebox
just by storing those 30 - 40 "widgets".

The same applies for other cable types.

Of course, this only works well at low bandwidths -- GHz plumbing
is a bit more involved!  :>
 
> Now just plug in the USB. Whats an *active* USB cable?

Passive is just wire.  An active cable has some (usually *powered*)
electronics in it for buffering, signal conditioning, etc.