Minecraft wiki entry for Tick, associated text: A redstone tick describes two game ticks. This creates a 1⁄10 of a second delay in the signal of a redstone circuit; that is, the signal's time to travel from a location A to location B is increased by 0.1 seconds. A tick pertains only to the increase in signal time, thus, a signal's travel time can never be decreased in reference to ticks. A redstone repeater has a delay of 1-4 redstone ticks. The default delay is 1 redstone tick, and pressing use item on the repeater increases it, visually indicated by the slider moving down the block.