Brightness control for dimming conventionally wound transformers with secondary-side low-voltage halogen lamps and / or incandescent lamps based on the leading edge principle

摘要

The dimmer has a multistage filter (1) between the line and neutral conductors to reject the audio frequency components in the mains and in addition, through a control circuit comprising a filter member (r1,c1), a multistage filter (the same one as before?) and a window discriminator(2), is in a position to reject DC components in the load current, generated by the magnetic properties of the load or by the control circuit itself, by suitable shifting of the firing angle. With unacceptably high phase-shifting in fault situations with unloaded transformers, the phase section is prolonged and the end stage is controlled for the whole time, thus preventing asymmetries.