Minecraft wiki entry for Clock, associated text: Design A shows a basic loop clock. The repeaters must have a total delay of at least 2 ticks, or the torch burns out. Powering the block turns off the clock. As many repeaters as needed can be added, and the loop can be expanded as needed with dust for cornering. The circuit as shown is flat, but large loops can be run onto multiple levels, to cut down on sprawl.