Minecraft wiki entry for Clock, associated text: While it isn't much discussed in the circuit builds below, there is one additional concept that is occasionally important: Phase. The phase of a running clock is the point it has reached in its cycle. For example, at one moment a 5 clock might be 3 ticks into its ON phase, 4 ticks later, it is 2 ticks into its OFF phase. A long-period clock might be noted as 2 minutes past the start of its ON phase. The exact beginning of a cycle depends on the clock, but it is usually the start of either the OFF phase or the ON phase. For most cases, phase doesn't matter because they just need pulses every 7 ticks or so. However, in-game computing circuits are more demanding, and if they are doing a daily clock, they should care whether the on phase is day or night.