Phone Talk / Apple Talk

From: Ron Hudson <ron.hudson_at_sbcglobal.net>
Date: Tue Aug 31 13:53:26 2004

On Aug 31, 2004, at 10:29 AM, Pete Turnbull wrote:

> On Aug 31 2004, 0:44, Ron Hudson wrote:
>
>> I am currently using an Imagewriter printer cable to hook up one
>> device, and that
>> seems to work ok, and there is no electronics there.. Perhaps the
>> transformers are
>> for some safety - decoupling purpose?
>
> You have the equivalent of a point-to-point link, with Tx on one device
> connected to Rx on the other. When you have things set up as a
> network, all the Txs go onto a bus that connects all the Rxs. The
> transformers allow the signals to combine, and separate them for each
> station.
>
> But I'd expect you could just find some proper boxes easily and cheaply
> enough; they're not rare, even here in the UK.

Here's the schematic from the site You mentioned...
==============
A "O" means a connection

PIN NUMBERS ARE FOR MAC DB-9.
NUMBERS IN () ARE FOR MINI DIN 8 (MAC PLUS)

           CapNet Connector (last update 8/21/90)

  J1 J2
        9 (5) C1 .1 uF
RCV(-) ----------------------------O----------][------O <myx>
                                    !
        8 (8) ! C2 .1 uF
RCV(+) --------------------------------O------][------O <myy>
                                    ! ! ^
                                    ! ! TO
        5 (3) 10 ohm ! ! "PHONE"
TX(-) -----------O-----------R3---- ! LINES
                   ! !
        4 (6) ! 10 ohm !
TX(+) -----------------O-----R4--------
                   ! !
              1K R R 1K
                   1 2
                   ! !
        3 (4) ! !
GND -----------O------


PARTS LIST:

QTY DES ITEM
2 R1,2 1K 1/8W RESISTORS
2 R3,4 10 OHM 1/8W RESISTORS
2 C1,2 .1 uF THREE LAYER CERAMIC CAPS
1 J1 DB-9 MALE OR MINI DIN 8 CONNECTOR
1 J2 2 PIN BERG OR RJ-11 PHONE CONNECTOR
5 WIRE (NOT SHOWN) 22 GAUGE STRANDED WIRE 6"

==============================

I assume I connect all the <MYX> together and all the <MYY> together to
actually join the
machines..

Since all 3 items are sitting in one place, I will probably build a
small PCB with 3 parts
of 2 printer cables cut in half.




>
> --
> Pete Peter Turnbull
> Network Manager
> University of York
>
Received on Tue Aug 31 2004 - 13:53:26 BST