I have just discovered that my new PDA (Fujitsu Siemens PocketLoox 720) has a line out on the cradle plug. This is opening up some great possibilities to use it as an in-car MP3 player as well as for SatNav /ubbthreads/images/graemlins/laugh.gif. I'm now looking into getting an active Brodit cradle for the PDA and modify the plug/cable myself so that it also carries the audio signal. The only problem is getting the signal into the Audi radio. I know that the CD changer inputs can be used for this and I'm sure that finding the line-in pins on the radio is simple enough, but what do I need to do to fool the Concert radio/cd into thinking there is a CD changer installed? The usual boxes that you can buy to create a aux input on Audi radios are too expensive to my taste. I'm quite good with electronics, so unless it is going to require programmable microcontrollers, I'm sure I can make something myself. All I need to know is which pin requires what kind of signal so that the radio thinks a CD changer is connected.