| 摘要 |
A solid-state electronic ballast circuit for supplying direct-current power to an electric discharge vapor lamp is disclosed. The source-drain channel of a Vertical Metal Oxide Semiconductor (VMOS) Field Effect Transistor (FET) is connected in parallel with a fixed ballast resistor, the parallel combination being connected in series with the lamp across a DC source. A resistance network controls the conductivity of a bipolar transistor, which in turn controls the conductivity of the VMOS channel, in response to variations in both lamp voltage and current. The ballast circuit may be manufactured as a part of the lamp bulb assembly, the ballast resistor taking the form of an incandescent lamp filament mounted in the same outer bulb with the vapor lamp arc tube. A variable resistance may be employed to manually adjust the level of illumination delivered by the lamp, or a light-sensitive phototransistor may be employed to deliver constant illumination. |
