Flashing lights controller BSU_xx is used for control of traffic lights, road markers on zebra crossings, railway crossings, etc. Two output channels of 24 V DC or 230 V AC versions switch alternately. Adjustable flashing frequency is displayed by LED indicator. Isolated synchronization port enables switching and synchronization of several lights, regardless of voltage or power line. Inverting or no-inverting synchronization can also be used for synchronization to an outer source. Switching element is so-called "zero-crossing", which switches at zero voltage to prevent any disturbing emissions to power line. Casing is prepared for DIN-rail mounting.