A Redstone Comparator is a Redstone device that compares the strengths of two different Redstone power sources to figure out whether or not a third Redstone connection should be powered. The Redstone Comparator consists of one short Redstone Torch at its “head,” two upright Redstone Torches at its “tail,” and two additional ports at the sides to take other sources of Redstone power. While relatively simple to craft, properly using a Redstone Comparator takes some understanding of the mechanics behind it.
How to craft a Redstone Comparator in Minecraft
Using a Crafting Table, a Redstone Comparator requires three Redstone Torches, three blocks of Stone along the bottom, and a piece of Nether Quartz at the center. The Stone blocks cannot be Cobblestone, Stone Brick blocks, Andesite, or any other Stone-like block. Only Stone that has been processed through a furnace or mined with a Silk Touch pickaxe will work in this crafting recipe.
Using a Redstone Comparator in Compare mode
When the short Redstone Torch to the head is unpowered and dim, the Redstone Comparator is in Compare mode. Comparators will automatically be in Compare mode when placed down, though right-clicking on it will change its current mode.
Related: How to make a redstone clock in Minecraft
When in Compare mode, the Comparator will, as its name implies, compare the strength of the Redstone power source toward its tail to the strength of the strongest Redstone source on either side. Redstone power is considered stronger the closer its source of power is to the Comparator. This means that, in theory, a Redstone Torch placed directly next to the Comparator is much stronger than a Redstone Torch separated by several blocks of Redstone wire.
If a Redstone source on either side is stronger than the source wired at the tail, the Redstone Comparator will stop the power from transferring to the head. However, if the source at the tail is closer than either side source, or if there are no other sources of power at the sides, the head will still receive power.
Using a Redstone Comparator in Subtract mode
After placing a Redstone Comparator down, right-clicking on it will switch it from working on Compare mode to Subtract mode. Doing so will cause the short Redstone Torch at the Comparator’s head to light up. Subtract mode works a bit opposite to how Compare mode works.
Rather than checking to see if a side source is stronger than the tail source and, if this is true, cutting off power to the head, Subtract mode instead subtracts the stronger of the two side sources from the strength of the tail source. If the answer to this subtraction is positive, and the side source is stronger than the tail source, power will flow through to the head. If the strengths at the head and side are equal, or if the head is stronger than the side, power will instead not flow through.
Looking to take your Redstone systems to the next level? Try using a few Redstone Repeaters to adjust timing.
