Discharge lamp operating inverter circuit with electric dimmer utilizing frequency control of the inverter

摘要

A circuit arrangement for operating a discharge lamp includes a DC-AC converter provided with a branch A having at least one switching element alternately conductive and non-conductive for generating a current of alternating polarity at a frequency f. A load branch B is coupled to the branch A and is provided with lamp connection terminals and with inductive means. A drive circuit E renders the switching element conducting and non-conducting at a frequency f. The drive circuit is provided with a branch D which includes a series circuit of further inductive means and capacitive means, and with a branch C including a variable impedance. The drive circuit is coupled to the inductive means in the load branch B, the branch D is coupled to the switching element in branch A, and the branch C is coupled to the further inductive means in branch D. Branch C also includes inductive means and the variable impedance is a variable resistor. The lamp thus can be dimmed over a wide range by a simple and inexpensive circuit.