A sensor assembly, comprising a housing having a receiving window covered by an optically transparent cover. The housing accommodates electric components, at least comprising a motion sensor and an ambient light sensor. The motion sensor and the ambient light sensor are positioned such that light entering the cover impinges on the motion sensor and the ambient light sensor. Between the cover and the ambient light sensor is an optical diffuser positioned, such that light entering the cover traverses the optical diffuser before impinging on the ambient light sensor. The sensor assembly may be used separately or incorporated in an electric or electronic device.