Drivers (2) comprise converters (21) for converting input signals from dimmers (1) into output signals destined for light emitting diode circuits (3) and controllers (22) for detecting dimming levels of the input signals and for bringing the drivers (2) from first, normal dimming modes into second, eco dimming modes in response to detection results defining the dimming levels being equal to/smaller than threshold levels. In the first/second dimming modes, the first input signals are converted into first/second output signals according to first/second curves (I, II). The second curves (II) define higher light outputs than the first curves (I) for most of the dimming levels. Dimmers (1) comprise indicators (11, 2, 13) for indicating to users the dimming levels of the input signals being equal to/smaller than the threshold levels. The indicators (11, 12, 13) may comprise light emitting diode 10 apparatuses (11), mechanical clicks when turning knobs (12) and markers or markings (13) on the dimmer.