Patent ID: 9642211
Date: 2017-05-02
CPC Classifications: G01N,G01R,H05B

Claim:
1. A detection circuit for detecting a presence of an operating dimmer arranged to dim a lamp, the detection circuit comprising: a first circuit configured to measure at one or more frequencies an impedance at a coupling arranged to carry a possibly dimmed feeding signal for the lamp and to provide a first output signal, the first output signal indicating the measured impedance at the one or more frequencies, the coupling being adapted to connect to a mains and the operating dimmer, and the one or more frequencies being higher than a mains frequency of the mains, and a second circuit configured to analyze the first output signal and to provide a second output signal, the second output signal indicating whether the operating dimmer is present, wherein the measured impedance comprises the impedance of the operating dimmer when the operating dimmer is present, and the second circuit is configured for providing the second output signal indicating the operating dimmer being present if the measured impedance changes by at least a defined minimum deviation within a defined time interval.