Abstract: An electrical ballast system having a toroidal current transformer having a core with a gap of predetermined dimensions, a primary winding, and a secondary winding. The primary winding is connected in series to a lamp load circuit and the secondary winding is connected to a transistor driver having an input. The improvement comprises the reduction of the effective area of the transformer core a sufficient amount to limit the output voltage amplitude of the secondary winding within a predetermined range compatible with the input of the transistor driver. The reduction of the effective area of the core is achieved with a cut or gap that covers up to 75% of the effective cross-sectional area. The resulting transformer will operate linearly for low load currents passing through the lamp and primary. For load currents above a predetermined magnitude, the core is saturated and additional magnetic flux lines pass through the gap, attenuated.

Abstract: An electronic ballast for gas lamp loads, such as ionized lamps, that includes a boost power factor correction used to correct the power factor and minimize the total harmonic distortion. The boost includes an inductor that periodically stores and discharges its resulting voltage in a charging capacitor through an optional bypass diode connected in parallel with an electronic switch using the oscillator that is applied to the load. The addition of the bypass diode decreases the total harmonic distortion. The inductor is selected, in combination with the rest of the circuit, so that it never reaches saturation. The inductor periodically charges the charging capacitor above (twice) the peak voltage that is supplied by a rectified continuous source of direct voltage. The high intensity discharge load is connected to a suitable resonant circuit.

Abstract: An electronic starter for high intensity discharge devices, such as mercury vapor, high pressure sodium, and metal halide lamps. The present invention includes voltage controlled oscillator with a resonant frequency that is determined by the direct voltage applied and by a resonance circuit that includes the high intensity device as part of the resonance circuit. A higher frequency of oscillation is present upon start-up before the device is ionized of approximately 300 kilohertz. After that, the high intensity device shunts out one of the capacitance reactive elements lowering the circuit's Q and maintaining an operating frequency that oscillates between 20 and 100 kilohertz. The inductive element acts as a current limiting device and a protection circuit is provided to monitor the voltage across the lamp and to disable the oscillator if abnormal conditions are detected including removal of the lamp.