Abstract: The invention relates to acoustic transducers which comprise a ceramic ring formed from a pre-stressed set of segments. It consists in using, as screws for tightening pre-stressing wedges, screws with hexagonal heads and in placing on the inner face of these wedges a plate provided with recesses in which the cants of these screw heads become anchored. This plate comprises transverse channels allowing the passage of the power supply wires for the sectors. The central screw is removed after the desired pre-stressing has been obtained. It makes it possible to improve the manufacture of these transducers.

Abstract: A user adjustable switching controller for duty cycle regulating flow of current to an electrical load such as a resistance heater, particularly for cooking appliances. A load current switch, when closed by a user operated cam also energizes a heat motor which includes a resistive strip attached to one active leg of a U-shaped bi-metal member. In one embodiment the integrally formed load current switch snap spring is securely attached to the heated leg of a U-shaped bi-metal and the moveable contact arm pivoted on the base. The other leg of the U-shaped bi-metal is anchored to a base including one of the load-connecting stationary terminals; and, the anchored leg serves to provide ambient temperature compensation. In another embodiment, the integrally formed blade spring of the moveable contact member is pivoted on the active leg of the U-shaped bi-metal and the moveable contact arm welded to the base.

Abstract: A temperature and voltage compensated time delay relay includes first and second bimetallic, contact carrying elements chosen to deflect in a similar manner in accordance with variations in ambient temperature for maintaining the contact gap therebetween substantially constant despite ambient temperature changes. A heater coil is wrapped about a first one of the elements (active element) for controlling the deflection thereof toward the second element (stationary element) for closing the contacts of the elements in a predetermined time period. An automotive flasher circuit having normally closed contacts and a flashing rate "on" time which varies inversely proportionally with an increase in supply voltage, is coupled electrically between the supply voltage and bimetallic element heating coil to control and keep relatively constant the rate of heat rise in the active bimetallic element and thus to maintain the time delay period of the relay relatively constant.

Abstract: A coil form for accommodating at least one coil winding and a heat switch. The coil form includes a recess for receiving the heat switch and the heat switch includes at least one switching element and a housing, at least a portion of which is adapted to be inserted into the recess. The housing is open at least in an area thereof adapted to be inserted into the recess and a portion of the housing serves for closing off the recess. The heat switch includes a base body and fixed connection elements on the base body which are insulated from each other. The heat switch includes a contact actuatable by a bimetallic switching member and a stationary counter contact with the contact and counter contacts being connected so as to be electrically conductive with the respective fixed connection elements at a predetermined temperature such that they are either electrically connected with each other by the bimetallic member or separated from each other.