Redstone Comparator (Inactive)

The Redstone Comparator is a complicated device in Minecraft. It has two operation modes, which can be toggled by right-clicking; the front torch indicates what mode it is in. Aside from these two actions, it has another two.

A vs. B

This part is simple, but vital to remember: When a signal comes in from the back (the side with two torches) it is Signal A. When it comes in from the side, it's Signal B.

Subtraction Mode

This mode takes the inputs from the side and the back and subtracts B from A. It then puts out a signal of that strength. Example: A Daylight Sensor at high noon is right next to the back and a Redstone Torch, 11 blocks away, is powering the side. The output from the front will have a strength of 15-10 (5).

Comparison Mode

Comparison Mode is triggered when the front torch is dark. It takes the signals of A and B and compares them. If B is stronger than A, no signal passes through. However, if A is stronger than B, it continues through.

Use as a diode

Redstone Comparators, although they cannot repeat a signal like a Redstone Repeater, can prevent signals from traveling in one direction but allow them through in the opposite direction. This is handy to make sure a Hopper powering a Comparator doesn't get turned off by a rebound of power.

Measuring Containers

When the back end is placed against a container of any type (Chest, Trapped Chest, Brewing Stand, Furnace, Hopper, etc.) it will send out a signal based on the number of items in that container. This is handy for alarms when someone has stolen something out of your chest. However, Trapped Chests can function in the same way, although they will go off when you open it too.


Technical Blocks
Liquids WaterLava
Redstone Piston ExtensionRedstone WireRedstone Torch (Off)Redstone Lamp (On)Redstone Repeater (On)Redstone Comparator (On)
Plants Nether Wart (Growing)Potato (Growing)Carrot (Growing)Wheat (Growing)
Misc FireEnd Portal (Block)Nether Portal (Block)Locked Chest
Crafted Blocks
Crafted Blocks Brick (Block)BeaconRedstone TorchBlock of DiamondBlock of EmeraldBlock of GoldBlock of RedstoneBlock of IronBlock of CoalBlock of Lapis LazuliFlower PotItem FrameHopperDropperDispenserLeverPressure PlateButtonDoorTrapdoorPolished AndesitePolished DioriteSlabBookshelfJack o'LanternStained GlassStained ClayBlock of QuartzChestCrafting TableFurnaceAnvilEnchantment TableEnder ChestTrapped ChestStained Glass PaneSlime BlockBedNote BlockSticky PistonRedstone LampFence GateRedstone RepeaterRedstone ComparatorPowered RailActivator RailBoatMinecartMinecart with FurnaceCakeBrewing StandCauldron

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