Abstract: A gas discharge lamp is connected across an inductor and in series with a solid state switching device and a resistor, and this combination is connected across a rectified AC voltage source. This switching device is controlled by a monostabile multivibrator, the input of which is connected to the output of a comparator amplifier sensing the difference between the voltage drop across the above-mentioned resistor and a voltage which may be selected to vary light intensity. The secondary winding of a step-up transformer connected to a capacitive discharge device is placed in series with the lamp. Control circuitry is provided to apply a large ignition voltage to the lamp while preventing damage to the switching device by simultaneously holding it in its conductive state. A diode rectifier provides an alternate current path across the secondary winding to prevent the inductance of the secondary winding from affecting normal lamp operation.

Abstract: A gas discharge lamp is connected across a step down auto transformer and in series with a solid state switching device and a resistor, and this combination is connected across a rectified AC voltage source. This switching device is controlled by a monostable multivibrator, the input of which is connected to the output of a comparator amplifier sensing the difference between the voltage drop across the above-mentioned resistor and a voltage which may be selected to vary light intensity. A starter aid conductor is placed adjacent the lamp and connected to the grounded side of the voltage source. This results in an efficient, high frequency operation of the lamp wherein the voltage gradient inside the lamp during starting ignition of the lamp is greatly increased to facilitate ignition despite the presence of the step down auto transformer, thereby permitting a decrease in the minimum fly back voltage necessary to start the lamp. As a result, reliability is increased.

Abstract: A gas discharge lamp is connected across an inductor and in series with a solid state switching device and a resistor, and this combination is connected across a voltage source. This switching device is controlled by a monostable multivibrator, the input of which is connected to the output of a comparator amplifier sensing the difference between the voltage drop across the above-mentioned resistor and a reference voltage which may be changed to vary light intensity. A supply voltage feedback control loop uses a power oscillator to maintain the voltage supplied to the inductor and the lamp at a level corresponding to a symmetrical voltage wave form in the lamp in order to maximize lamp efficiency. A reference voltage feedback control loop controls the reference voltage supplied to the comparator amplifier in order to minimize the effect of power line variations on lamp intensity while allowing controlled variations in intensity by the user.

Abstract: A gas discharge lamp is connected in parallel with an inductor and in series with a solid state switching device and a resistor, and this combination is connected across a rectified AC voltage source. This switching device is controlled by a monostable multivibrator, the input of which is connected to the output of a comparator amplifier sensing the difference between the voltage drop across the above-mentioned resistor and a voltage which bears a predetermined relationship to the rectified AC signal of said source. This results in a high frequency operation of the lamp wherein the lamp current level is controlled or modulated in accordance with the rectified AC supply voltage, providing a high power factor lamp circuit without the normal heavy lamp ballast. In addition, a circuit is disclosed which prohibits the lamp from exhibiting a high resistance when the AC voltage is at a zero crossing point, protecting the solid state switching device and stabilizing the high frequency.

Abstract: A gas discharge lamp is connected in parallel with an inductor and in series with a solid state switching device and a resistor, and this combination is connected across a DC voltage. This switching device is controlled by a monostable multivibrator, the input of which is connected to the output of a comparator amplifier sensing the difference between the voltage drop across the above mentioned resistor and the voltage of a variable reference voltage source.When the current through the inductor has increased to a point where the voltage drop across the resistor exceeds the voltage of the reference source, the comparator amplifier triggers the monostable multivibrator causing the solid state switching device to be turned off. This acts to collapse the magnetic field in the inductor thereby causing a large voltage to appear across the gas discharge lamp sufficient to light the lamp.