...making Linux just a little more fun!
Jim Jackson [jj at franjam.org.uk]
I was interested to see the discussion in this article on passive ethernet "hubs" etc. Other maybe interested in this passive 3 port ethernet hub design...
I've not actually built it yet, but plan to do so soon.
Ben Okopnik [ben at linuxgazette.net]
On Mon, Jul 09, 2007 at 02:30:40PM +0100, Jim Jackson wrote:
> > I was interested to see the discussion in this article on passive ethernet > "hubs" etc. Other maybe interested in this passive 3 port ethernet hub > design... > > http://www.zen22142.zen.co.uk/Circuits/Interface/pethhub.htm > > I've not actually built it yet, but plan to do so soon.
Pretty nifty idea for a project, that. A note of caution, though: given the operating frequencies for today's networks, you might want to think about the RF side of things. I.e., keep the wire runs as short as possible, and consider using twisted pair connections from the board to the Ethernet connectors. If I was going to build something like that, I'd probably attach the board to the center connector - or even attach all three connectors to the board (tiny as it is) and pot the whole thing in epoxy instead of using a case.
When I was working at Hughes Aircraft (a.k.a. "Huge Airscrap"), we all got a bit /blase/ about the distinction between high and low frequency; we worked with circuits that usually ran at double-digit gigahertz (D band, etc.), so stuff like FM radio and the oscillating frequency of hydrogen ions was beneath our notice. Much of that attitude suddenly went away after a certain project engineer wasted a day trying to get a power reading out of a receiver's IF section by connecting it to the power meter with a couple of feet of 18-gauge wire... the lab boss had left a message on the lab whiteboard, in large script, that said "400 MHz is NOT DC!!!"
(We checked out that wire later, by the way; ~20dBm loss at 400MHz, meaning that he was losing ~99% of the signal.)
-- * Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET *