Abstract: A circuit for automatically changing the amount of light provided by an illuminating source which contains a light sensitive device for monitoring the ambient light level. The light sensitive device controls current flow through a first path which includes the illumination source. A second path also provides current flow through the illumination source. When current is flowing through both paths, the source emits a predetermined amount of light. When only the second path conducts, the light provided by the illuminating source is substantially decreased.