Abstract: In a downconverter for supplying a DC current to a lamp, power feedback is achieved by adding a high frequency-operated switch and a capacitor to the topology. The power factor is improved thereby.

Abstract: A circuit arrangement for the high-frequency operation of a discharge lamp comprises a first rectifying circuit (D1-D4) for generating a DC voltage across a first capacitor (C1) from a low-frequency supply voltage. A DC/AC converter (IV) for generating a high-frequency AC voltage at a frequency f from the DC voltage is coupled to a load branch (B) provided with coupling means (T3, T4) for coupling the discharge lamp (Li) to the load branch. The load branch connects a junction point N1 of the DC/AC converter to a junction point N2 between the first rectifying circuit and the first capacitor. A second rectifying circuit for converting a high-frequency voltage generated by the DC/AC converter into a DC voltage is coupled to the first capacitor and to a junction point N3 in the load branch. A control circuit controls the power consumed by the discharge lamp through variation of the frequency f. The coupling means are connected between the junction point N2 and the junction point N3 in the load branch.

Abstract: A circuit arrangement for operating a discharge lamp. Input terminals are coupled to the poles of a supply voltage source which delivers a low frequency supply voltage. A rectifier is coupled to the input terminals for rectifying the low frequency supply voltage. A branch interconnects output terminals of the rectifier and includes a series arrangement of a first diode, a second diode, and a third diode. The first and second diodes are shunted by a first capacitor. The second and third diodes are shunted by a second capacitor. A resistor passes current during lamp operation with which the first and second capacitors are charged. Lamp current is generated based on the voltages across the first and second capacitors. The resistor is placed in a branch which passes a low frequency alternating current during lamp operation and which connects an input terminal to an input of the rectifier. The circuit arrangement has a high power factor.

Abstract: The invention relates to a circuit arrangement for operating a low-pressure discharge lamp. The circuit arrangement according to the invention comprises means X for supplying the low-pressure discharge lamp, provided with means X1 for generating a current of changing polarity. The circuit arrangement also comprises a feedback network which together with the means X and the low-pressure discharge lamp forms a control loop for controlling a lamp condition parameter. A low-pass filter is included in the control loop. The feedback network is provided with means M for generating a signal m which represents the instantaneous value of the lamp condition parameter, means C for comparing the signal m with a reference signal d, and means S for controlling the means X in dependence on the result of the comparison.

Abstract: An electronic supply for igniting and operating a high-pressure discharge lamp, comprising a first driven main switching device for generating a high-frequency current through an inductive element and a switching element suitable for subsequently supplying current through the inductive element when the first main switching device is non-conducting. The electronic supply is provided with a transformerless level shifter (LS) and with a driver circuit (S) comprising at least a switch drive device for driving the first driven main switching device. The switching element suitable for the subsequent current supply forms a part of a second driven main switching device which provides periodic commutation of the current through the inductive element, while the level shifter is free from any self-induction elements.

Abstract: The invention relates to a switching arrangement for operation of a high-pressure sodium discharge lamp by means of an adjustable power. Control of the adjustable power takes place by means of a control signal generated by optical sensing means for registering the spectral power of light emitted by the lamp. Registration of spectral power takes place in a first wavelength range between 350 nm and 800 nm.

Abstract: An electric arrangement for igniting and supplying a gas discharge lamp (13) has two input terminals (1, 2) intended to be connected to an AC power supply source. The output terminals of a rectifier bridge (4, 5, 6, 7) are connected in the operative state of the lamp to a DC/AC converter having two input terminals (A, B), one terminal (A) of which is connected to the other terminal (B) at least via a series arrangement of a first semiconductor switching element (9) and a load circuit comprising at least an induction coil (10) and the discharge lamp (13) as well as a capacitor (15). The load circuit and capacitor are shunted by a circuit comprising a second semiconductor switching element (16) and a parallel arrangement of a third semiconductor switching element (18) and a diode (17). The first two semiconductor switching elements are shunted by a buffer capacitor (8).

Abstract: A circuit arrangement for operating a high-pressure sodium lamp is provided with two lamp connection points. The circuit arrangement comprises a controlled main switching element, a control electrode of which is connected to a control circuit. The circuit arrangement is provided with a measuring impedance in series with a lamp connection point and with a measuring impedance parallel to the lamp connection points. The measuring impedances are connected to the control circuit. A combination of a resistor and a capacitor is further connected to the control circuit and this combination is connected in series with one lamp connection point.