A control device (100) for a chain of lamps comprises: - a power supply circuit (10); - a transformer (11), a resonant circuit 912) and a rectifier circuit 913) to convert an AC input into a DC output; - a control circuit (2)0) comprising a switching control terminal to receive a switching signal and output terminals to generate display control signals; - a driver circuit (30) which is connected to the control circuit to receive the display control signals and for the separate control of the lamp chain circuits as a reaction to them, these circuits being connected to the driver circuit; and - a timer circuit (50) which has a time constant and is connected to one of the output terminals of the control circuit to detect the full-load state of the lamp chain, the circuit having an output terminal which is connected with the switching control terminal of the control circuit. When the full-load state of the lamp chain circuit is established, the timer circuit generates the switching signal and outputs at the switching control terminal of the control circuit after a time period which is specified by the time constant to switch over the lamp chain into a part-load state.
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