Abstract: A ballast circuit for fluorescent lamp which comprises an additional D2 located just after the rectifier bridge D1 and before smoothing capacitors C5, C6. The diode D2 is matched to the value of a mylar capacitor C3 connected across the output of the rectifier bridge and the fluorescent lamp load whereby the fluorescent lamp draws current over substantially the whole of the supply voltage waveform to thereby improve the power factor and reduce the current harmonic distortion.

Abstract: A circuit for a plurality of electrical discharge lamps having a multiplicity of lighting functions comprises a common DC power supply/control unit with socket means to receive plug-in function modules common to all of said lamps, a socket means for connecting the power supply/control unit to an AC mains supply, a bus network and ballasts for respective ones of said plurality of lamps. Each of the plug-in function modules contains all the necessary circuitry and components for a desired lighting function and the ballasts are constructed as low cost disposable items comprising lamp driver circuits only.

Abstract: A plug-in fluorescent lamp assembly including a lightweight (e.g. plastic) light box that is adapted to either rest upon the existing support grid of a conventional false ceiling in a flush mounted arrangement or be attached directly to the ceiling in a surface mounted arrangement. The lamp assembly comprises a prewired electrical receptacle that is fixedly connected to the light box. Formed at one end of the receptacle is a socket at which the pins of one or more fluorescent tubes are to be removably received. Located at the opposite end of the receptacle is a terminal block that is to be detachably connected to a commercially available electronic ballast by which to drive the fluorescent tubes. By virtue of the plug-in or modular characteristics of the lamp assembly herein described, either a fluorescent tube and/or the ballast may be easily removed and quickly replaced in the event of failure without having to remove the light box from the ceiling or disturb the wiring of the receptacle.