Abstract: The present invention provides a bias supply selection circuit employable with a linear regulating device configured to provide a first bias supply voltage and a main bias supply stage configured to provide a second bias supply voltage. In one embodiment, the bias supply selection circuit includes a voltage monitoring circuit configured to monitor a level of the second bias supply voltage and to provide a control voltage proportional to the level. Additionally, the bias supply selection circuit includes a controllable switching circuit, coupled to the voltage monitoring circuit, configured to select the second bias supply voltage by deactivating the linear regulating device when the control voltage reaches a predetermined value.

Abstract: A symmetry control circuit for a ballast driving a gas discharge lamp. The circuit controls the pre-heat time of a gas discharge lamp with heatable filaments by holding off the full striking voltage until the lamp has had sufficient time to pre-heat. The circuit is designed to work with electronic ballasts and especially electronic ballasts without boost power factor correction to properly pre-heat the lamp. A control circuit reduces the duty cycle in an inverter transistor, thereby keeping the voltage across the lamp low while allowing filament heating to occur. The control circuit is disabled after a time interval of about 500 ms, allowing the transistor duty cycle to increase to 50 percent, the lamp voltage to rise, and the properly pre-heated lamp to ignite.

Abstract: A sun reflector formed by a carrier of transparent sheet material and internal louvers for use in a window panel is disclosed. The louvers are inserted across the width of the carrier and on equally spaced centers along its length. The louvers are received by the carrier at an angle acute to the plane of the surface. The louvers are formed of individual segments, each of which is equidistantly spaced from adjacent louver segments with the outer segments being spaced from the sides of the sheet material. The louver segments are encased by the sheet material.

Abstract: A curtain wall construction and anchorage structure for cooperatively mounting the curtain wall to and between floor slabs of a building is disclosed. The curtain wall is molded as a unit to a frame carrying anchorage structure. The curtain wall facade may be in the form of a plain face, formed to provide a contour and may include doors and/or windows. Additional anchorage structure is carried by the floor slabs. These structures cooperate to provide that mounting of the curtain wall is carried out by hanging the same on the building. The edges of each curtain wall are formed to provide interlocking and sealing engagement with the adjoining edge of an adjacent curtain wall.

Abstract: A self-supporting, modular structural panel comprises a rigid, opaque body panel of substantial thickness. One marginal edge portion of the body panel defines an integral, load-supporting beam which extends outwardly from a first major surface of the body panel. An exterior sheet member is bonded to and conforms to the contour of the body panel and beam. Marginal portions of the sheet are overlapped at an opposite marginal edge of the body panel to define an integral channel portion which extends outwardly from the first major surface of the body panel. The channel portion is configured to receive nestably and to interlock with the beam portion of a second structural member of like configuration.