Re: Building Appletalk board connectors?

[Eric Smith <eric@brouhaha.com>]

Michael J. Mahon wrote:
> I understood.  I was suggesting that the "Appletalk" connectors
> are available as S-video female connectors if he wanted to make
> a cable, or perhaps he could skip the mini-DIN and go straight
> to a phone connector...

The LocalTalk/PhoneNet box contain pulse transformers and a few
electronic components, not just wires.  The transformers are necessary
for electrical isolation so that a computer plugged into an electrical
outlet with a different ground level won't damage all the other machines
on the network.  (The same reason that Ethernet devices have pulse
transformers.)

This is also why LocalTalk has to use HDLC with biphase space encoding (also
known as FM0).  It has to be a DC-free code to pass through the
transformers.