S300 DRG 111 600mW Lighting Controller Detector, Cadmium Sulfide, Wall Mount, 230 V ac. These controllers automatically turn lights ‘ON’ and ‘OFF’ in response to changes in ambient light levels, primarily the transition from day to night and vice-versa. The more advanced types (see note below) have inbuilt logic to minimise false triggering, whereas the remainder have inbuilt time delays or higher ‘OFF’ thresholds, to prevent on/off cycling. As a general rule, these controllers should be sited such that they are not illuminated, by the light they are controlling. Nominal supply voltage is 230Vac.