I found out how it works myself.
You have to remove the back cover plate of your transmitter. Solder one wire to the ground of your battery and the other wire to the yellow wire at the print in your transmitter. (Yellow wire (2cm long )somewhere in the middle of the print ) Follow the rest of the guidelines at
www.heliguy.com/nexus/fmsinterface.html
resume
use npn transitor and 10k resistor
ground to emitter(npn) and parallel to pin 18 of male 25 sub D connector
signal from yellow wire to resistor and serial to base
collector to pin 10 of male 25 sub D connector
It works perfect.
Thanks again to Eric Wenger and of course Michael and Roman Möller for there beautiful site and program!!!!
Keep up the great work!
Send me an e-mail if you want extra info!!