Electrical circuit unit with moisture sealed plug-in connectors

By a special structure the conductor paths between connection prongs at one end of an electric circuit unit and circuit components located on two circuit boards are greatly shortened. The circuit boards are connected at their ends remote from the connector prongs by studs that releasably snap together while a flexible flat conductor makes connections between the two circuit boards. The two circuit boards are electrically and mechanically connected with separable parts of a plug connector each carrying at least one row of prongs projecting into a plug-in space of a receptacle body. One of these separable parts is integrated into a receptable body, which is provided with an aperture through which the other plug connector part can be slipped and locked into place after the boards have been electrically connected together at their far ends and the circuits have been checked.