Abstract: A power resistor for use in an automotive battery diagnosis circuit. The resistor includes a length of conductive material stamped to form a ribbon, which has formed along its length pins arranged perpendicular to the length of the ribbon and in a plane perpendicular to the stamping direction. The pins are arranged to provide in use means for electrical connection and mechanical fixation to the circuit.

Abstract: A resistor of a powered system includes an elongated body that extends from a first terminal end to an opposite second terminal end. The body forms a continuous path that extends from the first terminal end to the second terminal end and that forms a disc. The body is configured to receive electric current from the powered system at the first terminal end and conduct and provide electric resistance to the electric current received from the powered system to dissipate at least part of the electric current as heat from the body. The second terminal end of the body is configured to be coupled with at least one other resistor of the powered system in one or more of a parallel or series arrangement in an electric circuit.

Abstract: A resistor includes a first resistor element. The first resistor element is connected to at least a first electrical terminal and a second electrical terminal. The first resistor element is configured to directly contact cooling media on at least two surfaces of the first resistor element in order to transfer heat away from the first resistor element. The resistor may also include a second resistor element connected to at least the first electrical terminal and the second electrical terminal, where the second resistor element is configured to directly contact the cooling media on at least two surfaces of the second resistor element in order to transfer heat away from the second resistor element.

Abstract: Disclosed is a fractional bandgap circuit and method to provide a same reference voltage value in a variety of circumstances of operation, including variations in manufacturing process, temperature, and a supply voltage. The disclosed fractional bandgap circuit and method also allows for low supply voltage operation within a compact layout area.

Abstract: A resistor unit adapted to be used in a resistor grid assembly. The resistor unit includes a supporting element and a resistor element. The supporting element has an aperture formed therein. The resistor element has a body portion and a tip portion at an end, which is adapted to be received in the aperture to mount the resistor element to the supporting element. Further, a tab extends from the end of the resistor element forming a part of the resistor element. The tab is configured to provide a heat shield between the supporting element and the resistor element.

Abstract: An improved solid heat transfer element composed of an elongate member having a generally cylindrical surface with male vortex generating protrusions is provided. The vortex generating protrusions, which may be referred to as “turbulators,” provide improved heat transfer by convection to a flow of air transverse to the elongate members without substantially increasing the pressure drop in the flow of air passing over the members. Advantageously, a plurality of the heat transfer elements, or of straight portions of a single serpentine heat transfer element, may be arranged in an aligned or staggered array of elements or straight portions. Many advantageous profile shapes of the element and vortex generators are provided, including aerodynamic profile shapes that are symmetrical with respect to a fluid flow to provide low drag and pressure drop. Heat in the element may be generated by means of electrical resistance or absorption of radiation.

Abstract: A high-performance resistor includes resistor elements electrically connected in series and each having a first and second side and a first and second end. At the first end is a first connection and provided at the second end is a second connection for connecting the resistor elements. The first and second connections each have an inner portion and an outer portion. The inner portion of the first connection is bent at a predetermined angle with respect to the first side of the resistor element. The outer portion of the first connection is in a plane which is substantially parallel to the plane of the resistor element. The inner portion of the second connection is bent at a predetermined angle with respect to the second side of the resistor element. The outer portion of the second connection is in a plane which is substantially parallel to the plane of the resistor element.

Abstract: A fan resistor is formed with a resistive pattern of electrically conductive material sandwiched between two panels of thermally conductive material. An insulating barrier on each surface of the resistive pattern electrically insulates it from the thermally conductive panels. The resistive pattern is cut from a sheet of metal using a stamping machine and the cut resistive pattern is dropped on one of the panels, a surface of which has an electrically insulating barrier thereon.

Abstract: An electric heating device based on a ribbon of crystalline metal foil with high specific resistance, which is additionally treated to increase its plasticity and/or additionally coated with a mold release agent to enhance compatibility of the ribbon and insulating envelope. The ribbon combines high electrical resistance, high stability, sufficient mechanical strength and relative cheapness with very important properties including significant plasticity and compatibility with insulating polymers, including rubber and silicone. The above compatibility provides high reliability and life span. Different structures for flexible and rigid heaters on the basis of this ribbon are described, as are different applications.

Abstract: An actively externally cooled housing with at least one electronic component having heat-dissipating capacity, has a ventilation inlet located outside the housing, the ventilation inlet generating an airflow that is guided through a lateral flow channel, the flow channel being located on any side wall of the cooled housing on which at least one electronic component with heat-dissipating capacity is located, wherein the ventilation inlet is located in a ventilation housing that is located on the top side of the active-cooled housing and has a lateral air outlet that leads into the lateral flow channel, whereby an air intake occurs through only one air inlet opening that is located on the underside of the ventilation housing and which is essentially open vertically downward, so that the ventilation unit is located in the ventilation housing in such a manner that it is protected against impurities in the ambient air

Abstract: A Resistor bank has first and second supporting member. Held on to the supporting members is a resistor element comprising a strip of resistor material which is bent into a zigzag shape. The strip is continuous and has a non-planar cross section profile. A plurality of insulating spacers mounted end to end on each of the first and second supporting members isolate the element from the first and second supporting members. The engaging surfaces of adjacent spacers are of a complimentary shape thereby to enable each spacer to move relative to each adjacent spacer with any flexing of the relevant one of the supporting members. The element is held by a plurality of clips each at a bend thereof on to a respective one of the supporting members. Each clip has at least one fastening lug for insertion into at least one fastening hole in a corresponding bend in the element.

Abstract: A heat conductor coil for heating a flowing gaseous medium is configured to be attached to a support configuration and has a heat conductor wound in windings following an ascending line of a coil to form the heat conductor coil, wherein the ascending line of the coil defines a circumferential surface of the heat conductor coil. The heat conductor is deflected alternatingly in opposite directions within the circumferential surface of the coil out of the ascending line of the coil. The heat conductor coil is attached to a support plate by securing elements having a securing part for holding a winding of the heat conductor coil and a foot part for attaching the securing element to the support plate. The securing part is a tubular section with a substantially closed mantle surface and receives a winding of the heat conductor coil.

Abstract: A portable air temperature controlling device useful for warming air surrounding an aerosolized drug formulation. Warming the air of an aerosol makes it possible to reduce the diameter of aerosol particles produced by an aerosol generation device. Additionally, warming the air forces the diameter of the aerosol particles to be in the range required for systemic drug delivery independent of ambient conditions. Smaller particles can be more precisely targeted to different areas of the respiratory tract.

Abstract: An electric heating device includes a flexible resistor ribbon, a plurality of sections of electroconductive coating attached to the resistor ribbon at preset intervals, and connector contacts coupled to the resistor ribbon for enabling connection of a power source to the resistor ribbon. The resistor ribbon has a high specific impedance. The flexible resistor ribbon is attached to a rigid or flexible flat base panel for incorporation into a building as a floor, wall or ceiling panel. Layers of electric insulation are attached to the base so as to sandwich the flexible resistor ribbon. Where the resistor ribbon is bent back on itself, for example, to form a snaking configuration, a strip of two-sided adhesive tape is attached to the layers of electric insulation and to the ribbon at multiple spaced points.

Abstract: A multielement resistor may be assembled into a matrix from a plurality of resistor elements (12) of a U shape construction. The elements (12) are suspended from their upper portions by connecting brackets (16) which are supported by a supporting frame (14). Connecting brackets are preferably of electrically conducting material and insulated from supporting frame (14). Power input/output brackets (18) are provided.

Abstract: An FBT (fly-back transformer), its bleeder resistor (installed on the top of the FBT), and a device for coupling the bleeder resistor are disclosed. The bleeder resistor 100 is accommodated within a resistor case 180, and the resistor case 180 is installed on the top of an FBT case 110. A resistor pattern 140 is printed on the substrate 130 of the bleeder resistor 100. Openings 150 are formed within the wavy portions of the resistor pattern 140, and the resistor case 180 has a plurality of isolating sheets 160 within its interior 170, so that the isolating sheets 160 can be inserted into the openings 150. When manufacturing the bleeder resistor, the glass coating, the baking, the epoxy resin dipping are eliminated, but the voltage breakdown resisting property is improved. Further, the manufacturing cost is lowered owing to the simplification of the process.

Abstract: An improved surface mount resistor and method for making the same includes a body comprised of an elongated strip of electrically resistive material and a resistor terminal formed at each end of the resistive material. The resistive material is machined with a laser beam to create a current path having a desired resistance. The pattern cut is determined by partitioning the resistive material into a plurality of squares forming a current path through the resistive material with the correct resistivity. The resistive material is cut primarily with axial cuts so that the beam strength of the resistive material is maintained.

Abstract: A continuous ribbon resistor element having a plurality of conjunctive lengths alternately connected by reflexes is supported in a frame comprised of silicon bonded laminated mica. The ribbon elements are formed with a single, flat convolution center offset to one side of an original plane and lateral portions offset to an opposite side of the plane, joined to the center offset by transition portions such that the centroid for any transverse cross section lies on the original plane. The offsets originate at flat end portions near the reflexes and have maximum offset intermediate the ends. Metal members are received in openings of the laminated mica insulators to receive threaded fasteners when attaching an insulator in edge-wise relationship to another. Thermally conductive termination connections are brought outside the frame and airflow passageway to remove from the passageway the additional heat otherwise absorbed by the terminals.

Abstract: A resistor comprising a substantially continuous resistor element being formed into a plurality of element panels with each panel having at least two holes provided therein. Adjacent element panels are connected in series by a bend in the resistor element. At least two support tubes comprising an insulating material are provided to support the resistor element. A plurality of conductive washers are provided adjacent each hole on both sides of each element panel to provide a conductive heat sink near each support tube hole in the element panels. Insulating washers are spaced between adjacent conductive washers. Two end walls are provided adjacent opposing sides of the resistor element to receive the support tubes.

Abstract: A heating device has a plurality of strip heating portions separated by a plurality of slits. The strip heating portions are connected to one another by connecting portions, thereby forming a heating surface in which a zigzag current path extends. The connecting portions in which uneven-temperature regions exist are bent so as not to be positioned in the same plane as the heating surface, thereby making the heating surface, to be opposed to an object to be heated, to have a uniform temperature.

Abstract: A resistor grid assembly has a continuous resistor weave with a plurality of generally parallel, plate-like electrical elements. U-shaped bends join two adjacent elements at adjacent ends. The U-shaped bends are located in a bottom group and a top group. There is a top electrical insulating member adjacent the U-shaped bends in the top group and spaced from the U-shaped bends. There is a bottom electrical insulating member adjacent the U-shaped bends in the bottom group. Stop U-shaped pins having a pair of legs with a pair of shoulders are supported by the bottom electrical insulating member. The legs of each stop U-shaped pin extends into a pair of holes in the bottom group of U-shaped pins and rest upon the shoulders which are spaced from the insulator. Wire U-shaped pins are supported by the top electrical insulating member. The wire U-shaped pins have legs inserted into holes in the U-shaped bends in the top group. The U-shaped bends in the top group are spaced from the top insulator.

Abstract: A heating device has a plurality of strip heating portions separated by a plurality of slits. The strip heating portions are connected to one another by connecting portions, thereby forming a heating surface in which a zigzag current path extends. The connecting portions in which uneven-temperature regions exist are bent so as not to be positioned in the same plane as the heating surface, thereby making the heating surface, to be opposed to an object to be heated, to have a uniform temperature.

Abstract: An electrical heating system uses heating elements made of ribbons of amorphous metallic alloys. The heating elements have a large area using long and wide ribbons, to achieve good heat transfer to the surroundings, that is low thermal resistance. The area of the heating elements and thus the thermal resistance is determined according to the desired thermal power, under the constraint of a low operating temperature, that is a temperature well below the embrittlement temperature of the amorphous alloy used in the heating elements. The operating temperature is preferably kept low enough so as not to generate benzopyrene or other unhealthy or ecologically unfavorable fumes or gases. The thin ribbons with low thermal resistance also have a fast heating constant, that is the heater reaches its steady state temperature in a short time. The electrical heating system uses low cost insulation and support materials, that is materials intended for use at low temperatures only.

Abstract: Flow-through fluid heaters useful, e.g., for the preheating of exhaust gas streams prior to catalytic treatment thereof, are made by bonding an electrically conductive metallic film or foil to at least one pre-sintered flexible ceramic foil substrate to provide a flexible, electrically conductive ceramic/metallic heating element, that element then being formed into a crimped sheet or base sheet for incorporation into a honeycomb structure which includes a plurality of open channels extending from one surface of the structure to another surface of the structure, formed by one or more contacting combinations of crimped sheet and base sheet. Catalytic coatings may be applied to the preheaters to provide a heater/converter with very rapid light-off characteristics.

Abstract: The power loads in certain applications such as dummy antennas must have a substantially constant impedance in a wide band of frequencies. The power load is air-cooled and its resistive element is constituted by the series-connection of resistor modules made of expanded metal. Capacitors are positioned in a branching connection on the resistive element. The positioning of the capacitors along the resistive element and their value are determined to ensure frequency compensation.

Abstract: A heat dissipating fabricated resistor grid for the dynamic braking of electric motors has a zigzag resistor supported by insulating members within a frame. The zigzag resistor is made up of a plurality of resistor elements formed from sheet metal, each element containing at least one "U" shaped bend, that are connected by welded joints between the legs of adjacent resistor elements. The resistor elements may be embossed to stiffen them. Various types of clips may be utilized to hold the tabs and the resistor elements together to facilitate welding and the clips are welded to the other components and become part of the zigzag resistor. Various types of connecting joints are provided to connect the zigzag resistor to the insulating members. Various types of securing devices are provided to secure the insulating members to a supporting metal frame.

Abstract: A resistor grid for dynamic braking of diesel electric locomotives has a rigid frame that includes outer metal side pieces and metal dividers within the frame between which are positioned columns of fan-folded resistor ribbon. The dividers carry support plates having transverse aligned tabs along both sides fixed normal to the support plate, each tab having a notch in its inside edge, and supported plates for the resistor ribbon which slide in those slots longitudinally. The supported plates and the folds of the resistor ribbon carry studs and bushings which interfit by movement normal to those plates.

Abstract: A resistor element including a cylindrical ceramic support having two openings open on longitudinally opposite end faces thereof, an electrically resistive layer formed on an outer circumferential surface, a pair of electrical conductors for connecting the electrically resistive layer to an external circuit, each of which has an end portion inserted into a corresponding one of the openings of the ceramic support, and an electrically conductive adhesive filling each opening of the ceramic support, for securing the end portion of the corresponding conductor to the ceramic support. The electrically resistive layer has two integrally formed extensions for covering the opposite end faces of the ceramic support, respectively, and respective inner wall surfaces of the openings of the ceramic support. The conductors are electrically connected to the extensions of the resistive layer by the electrically conductive adhesive filling each opening of the ceramic support.

Abstract: An improved frame supported resistor grid used for dynamic braking of electric motors is provided. The resistor grid has a metal frame and fan-folded strips of resistance material arranged in columns within the frame. The strips of resistance material are supported by studs affixed to the folds of the strips and the studs are, in turn, supported in ceramic bushing insulators. An intermediate member is affixed to the frame and receives the individual ceramic bushing insulators.

Abstract: A fan-folded resistor ribbon is provided for use in resistor grids that are used for dynamic braking of diesel electric locomotives. The resistor ribbon is formed, from a continuous strip of resistance material, into flat portions that are connected by semi-tubular end loops. The outer surface of each semi-tubular end loop is an arcuate cylindrical surface that extends an angular distance of more than 180.degree. between the intersection lines where the flat portions join each of the end loops. The flat portions of the ribbon are embossed with one concave embossment and one convex embossment to further stiffen the ribbon material.

Abstract: A resistor grid for dynamic braking of diesel electric locomotives has a rigid frame comprising outer metal side pieces and metal dividers within the frame between which are positioned columns of fan-folded resistor ribbon. The dividers carry support plates having transverse aligned tabs along both sides fixed normal to the support plate, each tab having a notch in its inside edge, supported plates which slide in those slots longitudinally, the supported plates and the folds of the resistor ribbon carrying studs and bushings which interfit by movement normal to those plates.

Abstract: A heat dissipating resistor grid has a rectangular or annular frame including side members carrying blocks or panels of insulating material having cavities in their inner surfaces. The resistor element is a zigzag strip formed from individual flat lengths of resistance material, each length having offset ends in opposite directions, adjoining offset ends forming a sandwich with a conductive support strip which extends beyond the offset end and terminates in projections which mate with the cavities in the insulating material. The support strip may extend into the space between the adjoining strips of resistance material forming a heat sink therein. The projecting ends of the support strip may be flat lengths, may be cut into tabs, may be formed into hollow cylinders in one piece with the support strip, may be solid cylindrical studs affixed to the support strip, or solid rod bent into U-shape with the base inside the offset ends.

Abstract: An infra-red heater for a hybrid oven drying a web with an elongate foil having transverse corrugations heating element within a quartz tube. A thermocouple sensor is used to provide a control signal to a controller to regulate the infra-red output.

Abstract: A flexible induction heating coil comprising an elongated flexible core having proximal and distal ends. The core includes a plurality of core segments flexibly interconnected to make the core more flexible than the individual core segments. An elongated flexible inductor extends along the core.

Abstract: A heat dissipating resistor grid has a frame including side members carrying blocks or panels of insulating material having cavities in their inner surfaces. The resistor element is a zigzag strip formed from individual flat lengths of resistance material, each length having offset ends in opposite directions, adjoining offset ends forming a sandwich with a conductive support strip which extends beyond the offset end and terminates in projections which mate with the cavities in the insulating material. The support strip may extend into the space between the adjoining strips of resistance material forming a heat sink therein. The projecting ends of the support strip may be flat lengths, may be cut into tabs, may be formed into hollow cylinders in one piece with the support strip, may be solid cylindrical studs affixed to the support strip, or solid rod bent into U-shape with the base inside the offset ends. The insulating blocks may fit into cutouts in the frame and locked there by lateral movement.

Abstract: A resistor grid for dynamic braking and the like has a fan-folded strip of resistance material mounted in a frame. The strip is embossed longitudinally so as to stiffen it between folds or loops and lanced or slit longitudinally between embossments from fold to fold but not around folds.

Abstract: A resistor grid suitable for dynamic braking of diesel electric locomotives includes an upright rectangular frame with top and bottom members of insulating material and a strip of resistance material fan-folded into vertical flights between the top and bottom members. Fixtures attached to the top member suspend the fan-folded strip by its top folds and fittings affixed to the bottom member tension the fan-folded strip through its bottom folds.

Abstract: A sheet switch comprises a pair of flexible insulative films, one of which is provided with a plurality of electrodes, resistances connected to the electrodes, respectively, and line patterns for externally connecting the electrodes via the resistances. The other insulative film is also provided with a plurality of second electrodes at positions corresponding to the first electrodes, respectively, and a space is defined between each of the facing electrodes. The line pattern is a laminated structure consisting of an underlayer formed of a low resistance paste and an upper layer formed of a high resistance paste coated over the underlayer. The underlayer formed of a low resistance paste is partially disconnected to define a gap, so that the resistance is formed integrally with the upper layer formed of a high resistance paste at a position corresponding to the gap.

Abstract: An electrical heating element with a heat conductor in the form of meander-shaped windings, in which the individual windings are held in openings separated by solid parts in at least one insulating plate. For stabilization, especially with long, narrow designs of such a heating element, a retaining rail is provided, which extends over the entire width of insulaitng plates and essentially over their length and has tabs bent over along the side edges of insulating plates to grip the plates on both sides.

Abstract: In the assembly two or more strips of resistance material are positioned edge-to-edge and fan-folded between the side members of a frame. The strips are supported at their loops by insulated fixtures and each has a terminal at each end. The strips are embossed or indented between loops so as to form longitudinally extending offsets spaced from each other across the strip. The depth of those offsets is controlled so that the clear space between the adjoining flights is just sufficient to admit a flat metal strip inserted between them crosswise with a portion projecting to form a tap. That tap can be positioned anywhere between parallel flights of the resistor ribbon after the assembly of the unit. A channel-shaped clip fits over the projecting tap and the edges of the adjoining flights of resistor ribbon and is welded to the tap and the flights.

Abstract: A two-dimensional array of binary values is used to control operation of a bi-level imaging device. The array of binary values is formed by applying an enhanced array g(u,v) to a two-dimensional array of threshold values. A two-dimensional array of pixel value f(u,v) is used to form the enhanced array g(u,v) such that g(u,v)=m.sub.f +k[f(u,v)-m.sub.f ] where m.sub.f is the average value of f(u+a, v+b) from a=-L to a=+L and b=-M to b=+M and k is a gain function which depends on the standard deviation in f(u+c, v+d) from c=-N to c=+N and d=-P to d=+P. L, M, N and P define the sub-array over which the standard deviation is calculated. Preferably, L, M, N and P are each equal to 2. The value of k is a decreasing function of the standard deviation: the larger the standard deviation, the smaller the gain factor k. The rate at which k decreases with increase in the standard deviation depends on the edge sampling characteristics of the array of threshold values.

Abstract: A rigid frame supported resistor for dynamic braking of electric and diesel-electric locomotives has certain of the frame elements cushioned or insulated from each other and the resistance ribbon insulated and cushioned from the frame. Organic insulating material in molded or sheet form, preferably a copolymer, such as a polyester resin, protected by a metal heat shield, may be used for structural frame members, or for cushioning and insulating metal structural frame members. The organic insulating resistant is supplemented by ceramic insulating material in locations subject to high heat.

Abstract: A resistance heating element of the ribbon type for use in a high temperature electric furnace. The element has the same curved cross-sectional configuration throughout its entire length to give it strength and stiffness and permits the element to be bent into various patterns without any overlapping portions at the bends. The curved cross-section permits the element to be supported at the bends without the element sagging reducing the amount of heat absorption by the supports and allowing greater exposure of the element.

Abstract: An electrical radiator, particularly for fan-forced heaters, is provided which includes a resistance heating element disposed on an insulating element connected to the housing of the fan-forced heater. The coil winding of the resistance heating element is secured to the insulating element by means of clamping elements and is freely extending therefrom. A bimetallic switch in series with the resistance heating element serves as a heat protective switch and is disposed on a connector bar connected to the insulating element and carrying the electrical connectors for the coil winding. One end of the coil winding is secured on one side of the bar to a first bracket remote from the insulating element and which is rigid with the bar and connected to a first connector. The other end of the coil winding is secured to a second bracket disposed on the other side of the bar near the insulating element and which is rigid with the bar.

Abstract: A grid resistor assembly includes a plurality of flat grid resistor elements. Each element includes at least one open-ended loop having side portions and a tip end portion connected together through intervening strip portions of narrower width than the side portions to improve current carrying capacity and to provide for more even heating and heat dissipation. An assembly of such elements is particularly used as a resistor box in an electric, motor-driven, transit vehicle, such as a subway car, and is provided in a predetermined space envelope to perform predetermined electrical parameters.

Abstract: An electrically energizable high intensity, radiant energy heater (8) having a general M-shape for providing a pocket (20) for localized high intensity isothermal heating for fusion and fiber processing. The heater is shaped to provide easy access for a fiber (18) at an entry (16) to enable insertion of the fiber into the isothermal high temperature zone in pocket (20). A second re-entrant wall external to the pocket provides radiant shielding and buffers the isothermal heating zone from the cool environment. The heater may be constructed from a ribbon of a resistively heated metal, such as platinum foil.

Abstract: The resistor assembly includes a plurality of resistor sections each in the form of resistive plates in which slots have been cut to provide a continuous resistive element of low inductance. The resistor sections are stacked together with thin insulating sheets separating adjacent resistor sections. The resistor sections are serially interconnected. Taps are provided on selected resistor sections to form a plurality of serially connected resistors in which each resistor is electrically isolated from an adjacent resistor but closely thermally coupled thereto. The resistive plates are bound together by discrete bands of an insulating material such as glass cloth tape. Epoxy impregnation allows the resistor assembly when connected in shunt with series connected superconductive coils to be immersed in the liquid helium of a magnet cryostat without causing excessive pressure rise during a quench event.

Abstract: The invention is an elongated radiant electrical heater. An elongated parabolic shaped reflector has mounted at its focal point a ribbon heater. A thermal insulation material is mounted on the side of the ribbon heater opposite from the side of the focus where the reflector is positioned. The radiant ribbon heater is deeply corrugated with the height of each corrugation being a multiple of two to three times the width of each corrugation whereby the deep corrugations not only provide mechanical strength, but also increase effective emission per unit area of the radiant heating element.

Abstract: Resistance heating element, with a heat conductor led in meander pattern, which is fastened in the zone of the meander arches in bearing elements, characterized in that between the bearing elements there is arranged a heating conductor of at least one one-piece sheet metal stamped part strip (4) with bearing pins (25) and slide pins (27).

Abstract: An improved high intensity electricl resistance heater unit comprising one or more elongate thin metal foil ribbons adapted to be heated to a high temperature by passage of electricity therethrough, a thermally insulating rigid backing for supporting each ribbon, the backing having an elongate channel in a front face thereof for receiving the ribbon with side edges of the channel being undercut to form side grooves to receive and contain longitudinal side edge portions of the ribbon to support the same along the length of the channel while leaving the major surface of the ribbon unobstructed for heat radiation therefrom. A plurality of ribbons may be mounted in the backing with all electrical metal connectors being shielded within the backing from exposure on the back face of the backing material. The ribbons may be transversely corrugated and the configuration, e.g., amplitude, of the corrugations varied along the length of the ribbons to vary the heat output along the length of the heater unit, if desired.