Abstract: The invention relates to a novel operating circuit for a discharge lamp, in the case of which the lamp electrodes are preheated by driving switching transistors of an oscillator circuit such that their frequencies are detuned with reference to the resonant frequency of the lamp circuit. The drive frequency is defined by an independent resonant circuit.

Abstract: A free-running circuit arrangement for operating a load, has at least one switching element, a freewheeling diode connected in an anti-parallel fashion relative to the main current direction of the at least one switching element, a load circuit and a control resonant circuit which comprises at least one control inductor and at least one self-capacitance of the at least one switching element. The at least one switching element has a control electrode, a working electrode and a reference electrode, a capacitance acting between the control and working electrodes that is coupled to the control resonant circuit such that energy is fed into the control resonant circuit by the charging and discharging current of this capacitance, the circuit arrangement having no components for feeding energy into the control resonant circuit by electromagnetic coupling.

Abstract: The invention relates to a novel operating circuit for a discharge lamp, in the case of which the lamp electrodes are preheated by driving switching transistors of an oscillator circuit such that their frequencies are detuned with reference to the resonant frequency of the lamp circuit. The drive frequency is defined by an independent resonant circuit.

Abstract: The present invention relates to a free-running circuit arrangement for operating a load (La), having at least one switching element (T1, T2), a freewheeling diode that is connected in an anti-parallel fashion relative to the main current direction of the at least one switching element (T1, T2), a load circuit (L3, C6, C5) and a control resonant circuit (L2, CE,T1, CE,T2) which comprises at least one control inductor (L2) and at least one self-capacitance (CE,T1, CE,T2) of the at least one switching element (T1, T2), the at least one switching element (T1, T2) having a control electrode, a working electrode and a reference electrode, there acting between the control electrode and the working electrode a capacitance (CM,T1, CM,T2) that is coupled to the control resonant circuit (L2, CE,T1, CE,T2) in such a way that energy is fed into the control resonant circuit (L2, CE,T1, CE,T2) by the charging and discharging current (ICM,T1, ICM,T2) of this capacitance (CM,T1, CM,T2), the circuit arrangement having no comp