Abstract: The present invention relates to power adaptors for solid state lighting units and fixtures, of a kind including light emitting diodes, one of the adaptors comprising an input for receiving a phase controlled input power signal of varying on-duration and a controller coupled to the input and operable to produce at least one pulsed output driving signal in which both the duration and height of the pulses are varied according to the on-duration of the input power signal, to thereby control a light intensity output of the solid state lighting unit, such that the output is made to vary in a way that substantially matches the intensity response of the human eye. Various other arrangements of power adaptors are described along with dimmer controllers for use with the power adaptors, including some which involve motion sensing techniques.