Abstract: A high efficiency, electronic ballast is taught for high pressure sodium (HPS) lamps. The ballast is powered by AC line current which is rectified so that 160 volts of direct current lights the lamp. The ballast maintains constant wattage to the lamp and constant line wattage. A striker circuit develops a high voltage, short duration pulse to strike the lamp.

Abstract: A temperature switch for HID lamp fixtures is provided to enable such lights to be operated at low temperatures on the order of minus forty degrees Celsius, or minus fifteen degrees Fahrenheit. In one embodiment, the switch is comprised of a thermistor circuit and a resistive photocell circuit. When the resistance of either the thermistor or the photocell exceeds the reference value, or when the combined resistance of thermistor and the photocell exceed that value, the HID lamp will be turned on. The lamp is thereby turned on when the ambient temperature becomes very cold, regardless of the amount of ambient light in order that the components of the light fixture may be heated internally for more reliable operation.

Abstract: A striker circuit is provided for high intensity discharge lamps that uses a clamping circuit applied to the AC line current to generate a clamped voltage differential for striking the lamp. A clamped voltage differential is generated at fixed intervals until the lamp is struck. The emission of the clamped voltage differentials is stopped when the current flowing through the lamp is above a fixed value. The clamped voltage differential is reclamped if it drifts from its desired, clamped waveform.

Abstract: The invention comprises a self-adjusting ballast system for a high intensity discharge lamp. The ballast has a current limiter which modifies the lamp's present duty cycle to prevent damage if bulb rectification or another overcurrent condition occurs. It also has a current integration feedback loop for controlling lamp current during start-up.

Abstract: A self-adjusting ballast system for a high intensity discharge lamp. A lightweight, inexpensive and efficient ballast controls the strike and warmup stages of the high intensity discharge lamp, in particular high wattage lamps, through direct sensing of the radiant energy or heat output of the lamp itself. A current controller corrects for current imbalance in the alternating current lamp circuit due to bulb rectification or magnetic imbalance in the inverter transformer system.