On Sep 12, 9:51, Ethan Dicks wrote:
> --- Carlos Murillo <carlos_murillo_at_epm.net.co> wrote:
> > >> Now I have another question: How do you connect the Fastpath 4's
> > >> DE-9 Localtalk connector to a phonenet network?
> > >With a standard (ancient) DE-9<->PhoneNet adapter. Barring that, I
> > >have made DIN-8 to DE-9 LocalTalk adapters
> >
> > >You would need a female DIN-8 connector to go the other way.
> >
> > That would be the trickiest part... I think that I should
> > try wiring the DE9 directly to a 4wire phone cable; it is easier
> > to find a phone cable than a female DIN8.
>
> That won't work. The LocalTalk/PhoneNet adapters are not passthrus.
> Apple LocalTalk adapters contain self-terminating connectors (the
> plastic pip in the end of the cable pushes on a switch that disengages
> the internal terminator; PhoneNet adapters use RJ-11s with
> external terminators), and both adapters contain at least a transformer,
> IIRC to couple the Mac to the network. There might also be a resistor
> or two in the adapter. I haven't opened up one in over 10 years.
All the commercial LocalTalk and Phonenet adaptors contain an isolating
transformer, which is carefully designed to preserve nice clean square
waves from one side of the interface to the other. Note that you can't
just use any old small transformer! There's a web page describing the
innards at
http://ground.ecn.uiowa.edu/apple2/MiscInfo/Hardware/appletalk.phonenet
It's also commonly believed that the Farallon Phonenet system using
unsheilded cable works better than Apple's own grounded shielded cable
system.
However, I have seen one DIY design that didn't use an isolating
transformer. Called CapNet, it was intended for small networks, and used
capacitors to acheive some degree of isolation. A slightly updated version
was claimed to work with printers and the like.
http://hyperarchive.lcs.mit.edu/HyperArchive/Abstracts/info/hdwr/at-connector-substitute.txt.txt
http://www.loten-am-mac.yucom.be/cap1.htm
--
Pete Peter Turnbull
Network Manager
University of York
Received on Thu Sep 12 2002 - 15:51:00 BST