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Garmin to Mac Cable Idea

by German Alvarez

Date: Tue, 10 Feb 1998 23:00:00 -0500
To: Karen Nakamura 

From: German Alvarez 

Subject: gps cable using phoneNet

Karen, enclosed you will find a message I posted on the satellite-nav newsgroup, on how to use a PhoneNet connector to make a mac-gps cable.

I have tested it with excellent results on a g3 machine. I was concerned about using the shield instad of the GND, but it is working OK.

Feel free to edit/trash/publish it. I'm sure you can make it much more clear, my English is disastrous.

best regards,


Garmin to Mac cable idea

To make a cable to connect a garmin unit to a mac, I've used a discarded
phoneNet connector with very good results.

The main advantages of this approach are:

* you are spared to deal with the mini-din 8 connector for the mac

* you can easily fit into the phoneNet connector a power supply jack, and
if you want to be fancy a voltage level converter.

* probable you can get a discarded phoneNet compatible connector pretty

If you are not comfortable soldering, etc. Please ask for help. You can
damage your gps or computer.

In my particular case I used:
* power & data cable form garmin
* phoneNet compatible connector (AESP in this case)
* 1A 200V bridge rectifier
* 14000 micro F 25V condenser
* power supply jack, that fits a wall transformer of the appropriate voltage.

The idea of the rectifier and condenser is to let you almost use any wall
transformer you have available (AC or DC) in particular I wanted to use the
same one as I use for the modem to reduce desk clutter, and modem wall
adapters are usually AC.


Crack open the phoneNet connector, cut the circuit board inside the
connector to use the board like a terminal strip where you connect the
wires from the garmin cable to the mac cable.

Identify the Txd- (mini-din pin 3), GND (mini-din pin 4) and RxD- (mini-din
pin 5) cables in the circuit board, and solder the adecuate cables from the
garmin cable. You may not find a direct connection to Ground (pin 4), but
you can use the cable connected to the metallic shell of the mini-din
connector. It makes no difference in such a short distance and transmission

If you want to use the cable to feed power to your gps (recommended only in
garmin units with ample voltage input limits (6 - 40V)) connect the power
jack to the gps cable, be very careful with the polarity.
You can also put a bridge rectifier and condenser between the power jack
and the garmin cable (more info on this upon request) to use almost any
brick transformer AC or DC 6V - 24V you have available.

For more information about macintosh and gps pin-outs, visit:
http://www.gpsy.com/cables/ you will also find the excellent software
that forced my to build the cable :)

   German A. Alvarez


Copyright (C) 1997-98 by Karen Nakamura. All rights reserved. GPSy, GPSyLink, GPSy Pro and GPSY.COM are trademarks of Karen Nakamura. All other trademarks are the property of their respective owners.

We've had [N/A] hits since its creation on March 27th, 1997. This page was last updated on March 2nd, 1998.

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