[This document is a slight rewrite of an original by Tom Zerucha 
(tz@execpc.com).  I wanted to clarify some of his information and
add part numbers so one could more easily build this device.
----William 'Pete' Moss (bantha@bigfoot.com)]

Let me describe a simple adaptor I have since the only thing which can
easily go wrong is that the diode is in backwards or that the MIDI
connector is wired backwards.  It only provides play out from the device
with no recording capability.  Best thing is, it only costs a few bucks!

The parts (with Radio Shack catalog numbers) you will need are:
1x 9 position male D-subminiature connector (276-1537c)
1x silicon switching diode 1N4148 (276-1122)
1x 1/4 watt 220 ohm resistor (271-1313)
1x 5 pin DIN socket (274-005c)
2x #6 machine screws (~2" long)
6x #6 nuts
1x HotSync cable or PalmPilot cradle (for PalmPilot usage)
Some solder and a soldering iron


**** CONSTRUCTION ****
Looking at the solder lugs on the D-sub connector, with the longer side
at the top, the pinout is

 5   4   3   2   1


   9   8   7   6


My diode has the striped/marked end going into pin 5, and the resistor is
going into pin 2.

With these sticking straight out from the D-sub connector, I have a female
DIN connector attached, with the arc facing upward, i.e.

   +---------+
   |         |
-T-+---------+-T-
   +5-4-3-2-1+     The row of 5 pins is at the top
    | ' ' | '
    A     |    Diode with band toward pin 5 on the left
    V     U          Resistor on the right
    |     |
    \     /
     |   |
    i| i |i    The middle pin in the DIN is at the bottom
   [[[[H]]]]
 --+-------+--
   |       |
   +-------+

Use the screws to hold the thing together.
Attach the device to your HotSync cable (or cradle) and to a MIDI cable
to get MIDI output from your PalmPilot!


**** TROUBLESHOOTING ****
If you have it built, but it doesnt work, maybe you have the diode in
backward.  To test this, use a piece of wire to short around the diode.
If it works with this short, then the diode is backward.  Remove it and
turn it around.

If it still doesnt work, check the pictures below to make sure it is
soldered into the correct lugs.

For pictures of a completed unit, check out
http://www.execpc.com/~tz/aut_0011.jpg
http://www.execpc.com/~tz/aut_0012.jpg
http://www.execpc.com/~tz/aut_0013.jpg

Enjoy!