Abstract: An infrared radiating panel includes a wall made from ceramic fiber material. An electric heating element is adapted for connection to an electric current source for heating the element to a high temperature at which it will emit infrared radiation is fastened to the wall with the aid of staples. The heating element is mounted in spaced relationship with the surface of the wall and is retained between pairs of ceramic rods that engage opposite faces of the heating element.

Abstract: A serpentine etched foil heater has a segmented serpentine conductor group made up of a plurality of spaced-apart elongated serpentine conductive strips that are connected in parallel and are everywhere aligned with each other. Advantageously, central conductive strips are wider than are conductive strips along the edges. Further advantageously, the conductive strips are bridged by conductive regions that extend along lines of constant voltage. This makes it possible to handle the heater element without causing it to become tangled. The heater is especially suitable for low voltage applications.

Abstract: An electric hair curler comprises a handle and a barrel connected thereto for winding thereabout the hair. The barrel is provided with an electric heater for curling the hair wound on the barrel. The heater includes a plurality of resistor elements in the form of strips extending along the length of the barrel in generally parallel relationship with one another and being electrically connected in series by a corresponding number of bridging segments. The heater thus constructed is mounted on the barrel with the resistor elements thereof being exposed on the outer surface of the barrel in circumferentially spaced relationship with one another around the barrel, so that each of the resistor elements is in direct heat transfer contact with the hair to be wound on the barrel, thus greatly reducing the heat loss to assure effective heat transfer from the heater to the hair.

Abstract: An electrical network containing at least one electric resistor, includes a support foil and at least one resistance layer coating the support foil forming the at least one electric resistor. The support foil and resistance layer are folded along a zig-zag line forming two outer surfaces of the resistance layer. Contact layers are each disposed on a different one of the outer surfaces of the resistance layer, a plastic layer is applied on the contact layers, and outer contact layers each make contact with a different one of the contact layers. A method is also provided for producing the same.

Abstract: Device of thermoplastic material for making a perforation in an underlying element made of a plastics material compatible with the first-mentioned plastics material.It is composed of a plate (1) of relatively slight thickness, in one face (2) of which a spiral groove (3) is formed, at the center of which the plate is provided with an opening (1'), the said spiral groove being intended to receive an electric heating wire (19) of which one end is intended to be attached to a first projection (7) carried by the plate, on the side of the face in which the said groove is formed, while its other end is intended to be attached to a second projection (10) similar to the first and situated a certain distance from the latter.Application to the making of branch pipes.