Hi, First post here.

I have an A3 TDI pre-facelift (just) that came with the integrated telephone system (concert HU, with Cullman adaptor for Siemens c45).

The range of these adaptors is pretty limited & they don't do one for the S700i that I got recently. Does anyone know the pin outs of the adaptor cable?

I was thinking of modifying the adaptor to plug the new phone in but I need to know what that little circuit board inside the adaptor is designed to do.
Obviously there is a charging circuit, but does it do other things as well (impedance matching etc)?

If anyone has a circuit diagram (or schematic) for any of these adaptors I would be very grateful.