A turbidity sensor for use in a machine for washing articles, e.g., a washing machine (400). The turbidity sensor comprises a light source (210) for emitting light. The emitted light has a radiant intensity which is variable. The sensor further comprises a light-sensitive element (220) for receiving light emitted from the light source (210). The light source (211) and the light-sensitive element (220) are positioned relative to each other so that, when the light source (210) is in operation, light emitted from the light source (210) can propagate through a washing liquid contained in the washing machine (400) on its way to the light sensitive element (220). The light-sensitive element (220) is configured to measure the radiant intensity of light received at the light-sensitive element (221). Furthermore, the sensor comprises a controller (230) which is communicatively coupled to the light source (210) and the light-sensitive element (220). The controller (230) is configured to adjust the radiant intensity of the light emitted by the light source (210) in dependence of the measured radiant intensity of light received at the light-sensitive element (220).