Abstract: The embodiments described herein include a control system and method configured to communicate over a power line. The system includes a transmitting device configured to generate a carrier signal having a predetermined frequency over the power line. A receiving device is also included wherein it filters signals not having the predetermined frequency and receives the carrier signal. Accordingly, the receiving device activates an electrical device in response to the carrier signal.

Abstract: A rotary electrical switch for panel mounting in a motor vehicle for control of a blower motor of a heating, ventilating and/or air conditioning installation, includes a set of conductive contact strips. These comprise coplanar primary strips and a secondary strip for power supply. The switch has a body mounted for rotation about an axis at right angles to the plane of the coplanar contact strips. The body supports a radial ring member which is bent back into two half rings with conductive radial projecting portions connected together electrically. Each projecting portion carries at its end an arm having two contact pads for making contact with the primary contact strips in two parallel planes. The projecting portions have at least one third pad for making a further contact with the secondary contact strip in one of the two planes.