Minecraft wiki entry for Logic, associated text: The repeater is required to ensure the input signal is strong enough to overcome the comparator's rear source, but can be removed in a number of ways. If the input power level is known (because the circuit design is fixed, so it can be calculated), the repeater can be removed by replacing the powered lever with a container which will produce the same power level. Alternatively, the repeater can be removed if the output continues to a length of redstone wire which will reduce the subtracted signal enough that the signal is inverted eventually.