21 Apr
2013
21 Apr
'13
1:30 a.m.
A little impedance bump like that will have a minimal
effect at those
low-ish frequencies.
I'm reminded of the time I wanted to extend the an AUI Ethernet with a
DA15F, a DA15M, and some cable. I built the extender with about a foot
of ribbon cable grabbed from my ribbon cable stock without even
thinking about impedance and the like. It worked fine. As an
experiment, I made a similar cable with about 25 feet of ribbon cable
and it produced floods of errors, to the point where the Ethernet was
not usable.
Then I worked out that at 10 megabits, a bit on the wire was some
50-100 feet long (figuring effective signal speed as .5 to 1 c, about
right for high-frequency signals in copper twisted pairs), so it wasn't
much of a surprise that a one-foot impedance bump didn't do much but a
25-foot one did.
Mouse