Plug-in connector

A mechanical contact (16) fitted between plug contacts (8,9) allocated to devices is broken by a contact stud in a jack when a pin-and-socket connector is plugged together and shorts out as a plug (14) pulls out. To create free plug contacts (29,37) through which supplementary signals can be transmitted, when the pin-and-socket connector is plugged together, each contact stud breaks several mechanical contacts between the plug contacts of different devices.