wait a minute, i thought it was the exact same method 'cause i scanned the page and saw ppjoy... but it is in fact not the same circuit or even the same use of ppjoy.

the method you guys are using requires you to pass a ppm signal through your soundcard and convert it with software so ppjoy can see it. being an analog device, use of the soundcard will also require adjusting its input sensitivity. that adjustment, which you guys are doing with resistors, will vary from soundcard to soundcard. so, to get it to work those resistor values will probably have to be adjusted for every different soundcard. this is why some ppl may have a hard time getting to work using the same resistor values. just me, but that seems more complicated than the way i did it.

my method passes a logic signal straight to the parallel port, so everything stays digital (on or off, 0V or 5V, no in between voltages). although the circuit requires soldering a transistor, the design of the circuit is guaranteed to work on every pc that has a working parallel port, without having to modify resistor values.

regarding the phono plug: makers of phono plugs use a wide variety of standards, but usually the red colored wire is connected to the + part of the plug (the tip), and the other colored wire (in your case white) is connected to the - part (the shaft). you could check this if you have a multimeter to be sure, but red=+ is true for 99.9% of phono plugs i've played with (that's out of the 50+ different types of phono plugs i've rewiredin my lifetime). those copper strands that wrap around the inner wires are there to shield the audio signals from outside interference ; again 99.% of the time the shielding is connected to the - part of the plug (the shaft). so electrically the outer copper strands (shielding) are the same exact thing as the white wire (technically speaking, they form a single node).

for simplicity, the wire color scheme for your phono plug is:
red = +
white = - (same as black in your schematic)
copper shielding = - (same as black in your schematic)