I looked into the device from our friends at Radio Shack and found this:
http://support.radioshack.com/support_supplies/doc66/66324.pdf This is the
wiring diagram for the device - it does shows transistors (24 x 2N3904A). I
would guess that this is a very simple active hub. Wouldn't the transistors
"amplify" the signals? I'm not an EE but I can look a diagram and tell the
type of components are used.
I still would not use this kind of device. I place them in the same boat as
the "splitter" adaptors that you can place on both the ends of a cable that
utilize the "unused" wires.
James W. McKeand
From: Fred Wright [mailto:fw at well dot com]
Sent: Sunday, September 12, 2004 5:46 PM
To: m0n0wall at lists dot m0n0 dot ch
Subject: Re: [m0n0wall] Directly accessing the console?
On Tue, 7 Sep 2004, Seth Rothenberg wrote:
> you could look at Ethernet 10-Base-T Splitter
> This is not a cable splitter. It is basically a passive 2-port hub.
> I can't tell you how it conforms to net standars,
I'm reasonably certain that it doesn't. :-)
> but it comes in handy when your customer says "no signal"
> and you put a splitter between the client bridge and the PC, and you
> say, I have a link quality of 67...ping times of 3ms....
> (and then you can say, that's a windows problem :-)
> PS I had speculated that it was just 3 ports spliced together, and it
> is, but with some transistors at each juncture.
If it has transistors it's not a passive device, and would need a power
source. Are you sure it isn't transformers?
> It seems you can't just splice it together yourself.
Indeed. Notwithstanding that "Ethertap" page that someone periodically
posts a link to. That guy must have flunked EE 101.
And even if you get past the low-level electrical issues, there are other
issues that make this pretty ugly.
> PS PS PS!!!! Note! I did not check to see if this device is rated for
> use in a POE setting. POE fancy footwork may be needed, let me know
> if you have this problem.
Since PoE uses the extra pair that are unused by 10BaseT, it might work if
they just connected those together. It could get "intersting" if you
connected multiple PoE sources, though.
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