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The Redstone Comparator is a block for use with redstone circuitry. It has two inputs: one from the back ('signal A') and one from the side ('signal B'). If signal B is stronger than signal A, there will be no output. Otherwise, it can be set to either repeat signal A at its current strength, or output the difference between both inputs in subtraction mode.

It provides a "subtraction" feature which results in the output being the strength of the back ('signal A') minus the strength of the side ('signal B'), however for this to work the player must make sure that the front redstone torch is lit. Signal B has to be less powerful than signal A for it to work. An example is if the back has a strength of 15, and the side has a strength of 1 the output is 14. Right-clicking the comparator will toggle the torch.

The comparator also provides a feature which is activated when the rear of the comparator (the side with two redstone torches) is placed against a storage block. Doing this causes the comparator to emit a signal that is equal to the percentage the storage block is full. Some people call this fill-checking.

The comparator looks similar to a repeater, except with an additional redstone torch.

In American English (the wiki default), "comparator" is pronounced kuhm-par-uh-ter (kəmˈparətər in IPA), with the stress on the second syllable, but kom-puh-rey-ter, with the primary stress on the first syllable and secondary stress on the third, is used in some other countries.

Crafting

Ingredients Input » Output
Redstone Torches,

Stone, Nether Quartz

Template:Grid/Crafting Table

Uses

As a low-delay wire/diode

Like a repeater, the comparator acts as a diode. On its own, a comparator can be used as a diode (with 1 redstone tick delay), providing output of the same strength as its input, but not allowing current to flow against the direction of its arrow.

As a comparator

The comparator's side inputs may be used to set a threshold for the input signal. The input, signal A, will only be output if it is greater than or equal to signal B. Otherwise, there is no output. Signal A is the signal input to the back of the comparator. Signal B is considered the greater of the two side inputs; the weaker side input is ignored. This is similar to a real-life op-amp without a feedback circuit, with signal A to its non-inverting input and signal B to its inverting input.

As a diminisher

If a comparator is right-clicked, its third redstone torch becomes active. In this state, the output will be signal A minus signal B: the input signal will be reduced by the comparison signal. If signal B is greater than or equal to signal A, of course, there will be no output. This is similar to a real-life op-amp with a feedback wire from its output directly to its negative input (hence no amplifying effect but subtracts inputs), with signal A to its non-inverting input and signal B to its inverting input.


As a damper signal

If a line of 3 or more comparators are in a loop and then you increase one leg of the loop to 2 redstone before the next comparator, the signal strength outputted will then damper by 1 every sequence through the loop until the power dampers entirely.

As a clock

If a Redstone Torch or a Lever is connected directly to signal A and the output is forwarded to signal B and the comparator toggle is set to on, the device will act as a clock.

As an inventory contents checker

If a comparator is placed next to a container, it will provide an output based on the percentage of used space in the container. This includes: regular/large/trapped Chest, Furnace, Dispenser, Hopper, Brewing Stand, Dropper, Jukebox, or a Detector Rail with a Minecart with Chest / Hopper on it. The comparator may be separated from the input by one solid block if the 3 blocks form a line, however redstone current from below the separator may interfere. See below for more info.

Inventory checking output

When a container is empty, the output is off.

When it is not empty, the output signal strength is calculated as follows:

signal strength = truncate(1 + ((sum of all slots' fullnesses) / number of slots in container) * 14)

fullness of a slot = (amount of items in slot) / (max stack size for this type of item)

Example: 300 blocks in a dispenser (which has 9 slots), where each block stacks to a maximum of 64, produces output with a signal strength of 8:

1 + ((300 items / 64 items per slot) / 9 slots) * 14 = 8.292, truncated is 8

Note that a non-stackable item is counted as a full slot (1 item in a slot, with a max stack size of 1: 1 / 1 = 1.0), and items which stack up to 16 (such as ender pearls and snowballs) are similarly considered a full slot at 16.

Specific output signal strength creation

It can be useful in redstone circuits to use containers with comparators to create signals of a specific strength. The number of items required in a container to produce a signal of desired strength is calculated as follows:

items required = max(desired signal strength, roundup((total slots in container * 64 / 14) * (desired signal strength - 1) ) )

Example: To use a furnace (which has 3 slots) to create a strength 9 signal, you need 110 items:

max(8, (3*64/14)*(9-1)) = 109.714, rounded up is 110

Power listings of a chest

This chart shows the redstone output of a regular chest, with a items of stack size 64. (Note this does not include Large Chests.)

1 Blocks/items = 1 SignalStr

124 Blocks/items = 2 SignalStr

247 Blocks/items = 3 SignalStr

371 Blocks/items = 4 SignalStr

494 Blocks/items = 5 SignalStr

618 Blocks/items = 6 SignalStr

741 Blocks/items = 7 SignalStr

864 Blocks/items = 8 SignalStr

988 Blocks/items = 9 SignalStr

1111 Blocks/items = 10 SignalStr

1235 Blocks/items = 11 SignalStr

1358 Blocks/items = 12 SignalStr

1482 Blocks/items = 13 SignalStr

1605 Blocks/items = 14 SignalStr

1728 Blocks/items = 15 SignalStr

Jukebox record identification

Unlike most containers, the signal output by a jukebox represents the record it contains. It outputs:

Signal Record
0 none
1 13
2 cat
3 blocks
4 chirp
5 far
6 mall
7 mellohi
8 stal
9 strad
10 ward
11 11
12 wait
13 unused
14 unused
15 unused

Other Unique Block Outputs

End Portal Frame blocks output a full signal of 15 if they contain an Eye of Ender and zero otherwise.

Cauldrons output different signal strengths depending on how much water is inside. From completely empty to completely full, the output values are 0, 2, 3, and 4.

Command Block Output

Command Blocks output a property called "Success Count", which represents the number of times the most recently-used command of this Command Block succeeded. A "success" is defined by the command's success conditions: if a red error message is returned, the command was not successful.

Most commands can only succeed once per execution, but certain commands (such as those which accept players as arguments) can succeed multiple times, and the comparator will output the number of times it succeeded (of course, this is capped at a full signal of 15, so it will output 15 if there were 15 or more successes). Examples of such commands are /tell and /testfor. Note that /say will never output more than 1, as the command only outputs one message in chat regardless of the number of players who are referenced (their names are merely formatted as a list of the form "name1, name2, and name3").

Note that the comparator will output the Command Block's success count for the last command executed: it will be a constant signal (or lack thereof) and will only update when the command is next executed.

Video

Redstone Comparator/video

History

r
u
1.6
{{Extension DPL}}<ul><li>[[Clay Ball|Clay Ball]]<br/>{{Item
| image = Clay Ball.png
| stackable = Yes (64)
| renewable = Yes
}}

{{about|the item|the block|Clay|other uses|Clay (disambiguation)}}
A '''clay ball''' is the item obtained from [[clay]] used for [[crafting]] or making [[brick]]s.

== Obtaining ==

=== Block loot ===
Clay balls are obtained when a [[clay]] block is broken with a non-[[Silk Touch]] tool. Each block yields four clay balls regardless of [[Fortune]].

=== Chest loot ===
{{LootChestItem|clay-ball}}

=== Villager gifts ===

If a [[player]] has the [[Hero of the Village]] status effect, a Mason [[villager]] might throw that player a [[clay block]] as a gift. {{Only|java}} This can be placed and [[breaking|broken]] to harvest clay balls.

== Usage ==

Clay balls can be [[crafting|crafted]] back together to form [[clay]] blocks or baked in a [[furnace]] to create [[brick]]s.

=== Crafting ingredient  ===

{{crafting usage}}

=== Smelting ingredient ===

{{Smelting
|showname=1
|Clay Ball
|Brick
|0.3
}}

=== Trading ===
Novice-level [[Villager|mason villagers]] buy 10 clay balls for 1 [[emerald]] as part of their [[trades]].

== Data values ==
=== ID ===
{{edition|java}}:
{{ID table
|edition=java
|showforms=y
|generatetranslationkeys=y
|displayname=Clay Ball
|spritetype=item
|nameid=clay_ball
|form=item
|foot=1}}

{{edition|bedrock}}:
{{ID table
|edition=bedrock
|shownumericids=y
|showforms=y
|notshowbeitemforms=y
|generatetranslationkeys=y
|displayname=Clay
|spritetype=item
|nameid=clay_ball
|id=384
|form=item
|foot=1}}

== History ==
{{History|java alpha}}
{{History||v1.0.11|[[File:Clay Ball JE1 BE1.png|32px]] Added clay.}}
{{History|java}}
{{History||1.13|snap=17w47a|Prior to [[1.13/Flattening|''The Flattening'']], this [[item]]'s numeral ID was 337.}}
{{History||1.14|snap=18w43a|[[File:Clay Ball JE2 BE2.png|32px]] The texture of clay has been changed.}}
{{History|||snap=18w49a|Clay can now be found in [[chest]]s in [[village]] mason houses.}}
{{History|||snap=18w50a|Clay can now be found in [[chest]]s in [[desert]] [[village]] houses.}}
{{History|||snap=19w11a|Clay is now [[trading|bought]] by [[villager]]s of the new mason profession.}}
{{History||1.16|snap=20w06a|"Clay" has been renamed to "Clay Ball."}}
{{History|pocket alpha}}
{{History||v0.2.0|[[File:Clay Ball JE1 BE1.png|32px]] Added clay. It is currently unobtainable and serves no purpose.}}
{{History||v0.3.2|4 clay items are now dropped from clay blocks when broken.
|Clay can now be crafted into clay blocks.
|Clay can now be smelted into bricks.}}
{{History|bedrock}}
{{History||1.10.0|snap=beta 1.10.0.3|[[File:Clay Ball JE2 BE2.png|32px]] The texture of clay has been changed.|10–13 clay can now be [[trading|sold]] to stone mason [[villager]]s for an [[emerald]].}}
{{History||1.11.0|snap=beta 1.11.0.1|Clay can now be found in [[village]] mason [[chest]]s and [[desert]] village house chests.}}
{{History|||snap=beta 1.11.0.4|[[Trading]] has been changed, stone mason villagers now [[trading|buy]] 10 clay for an emerald<!-- previously 10-13 -->.}}
{{History||1.19.0|snap=beta 1.19.0.24|Clay ball now [[renewable]] by placing [[mud]] above a block which has [[pointed dripstone]] underneath.}}

{{History|console}}
{{History||xbox=TU1|xbone=CU1|ps=1.0|wiiu=Patch 1|[[File:Clay Ball JE1 BE1.png|32px]] Added clay.}}
{{History||xbox=none|xbone=none|ps=1.90|wiiu=none|switch=none|[[File:Clay Ball JE2 BE2.png|32px]] The texture of clay has been changed.}}

{{History|3ds}}
{{History||0.1.0|[[File:Clay Ball JE1 BE1.png|32px]] Added clay.}}
{{History|foot}}

== Issues ==

{{issue list}}

== Gallery ==
<gallery>
File:ClayInNumerousForms.png
</gallery>

== Notes ==
{{fnlist}}
{{Items}}

[[cs:Jíl]]
[[de:Tonklumpen]]
[[es:Bola de arcilla]]
[[fr:Motte d'argile]]
[[hu:Agyag (Tárgy)]]
[[it:Zolla di argilla]]
[[ja:粘土玉]]
[[ko:점토 덩이]]
[[nl:Klei (voorwerp)]]
[[pl:Glina]]
[[pt:Bola de argila]]
[[ru:Глина]]
[[uk:Глиняна кулька]]
[[zh:黏土球]]</li><li>[[Dried Kelp|Dried Kelp]]<br/>{{about|the item|the block|Dried Kelp Block}}
{{Item
| title = Dried Kelp
| image = Dried Kelp.png
| renewable = Yes
| heals = {{hunger|1}}
| stackable = Yes (64)
}}

'''Dried kelp''' is a [[food]] item that can be quickly eaten by the [[player]]. It can also be crafted into [[Dried Kelp Block|dried kelp blocks]].

== Obtaining ==

=== Cooking ===
[[Kelp]] can be cooked in a [[furnace]], [[smoker]], or [[campfire]]. Each piece of dried kelp removed from a furnace output slot gives 0.1 [[experience]] (6.4 experience per stack).
{{Smelting
|Kelp
|Dried Kelp
|0,1
}}

=== Crafting ===
{{Crafting
 |Dried Kelp Block
 |Output= Dried Kelp,9
 |type= Foodstuff
}}

== Usage ==

=== Food ===
[[File:Eating dried kelp.png|thumb|A player eating dried kelp.]]
To eat dried kelp, press and hold {{control|use}} while it is selected in the hotbar. Eating one restores {{hunger|1}} [[hunger]] and 0.6{{only|je|short=1}} / 0.2{{only|be|short=1}} hunger [[Hunger#Mechanics|saturation]].

A player can consume dried kelp about twice as fast as any other food item in the game.

=== Crafting ingredient ===

{{Crafting usage}}

=== Composting ===
Dried kelp placed into a [[composter]] has a 30% chance of raising the compost level by 1.

==Sounds==
{{Sound table/Entity/Food}}

== Achievements ==

{{load achievements|Castaway}}

== Advancements ==

{{load advancements|Husbandry;A Balanced Diet}}

== Data values ==
=== ID ===
{{edition|java}}:
{{ID table
|edition=java
|showforms=y
|generatetranslationkeys=y
|displayname=Dried Kelp
|spritetype=item
|nameid=dried_kelp
|form=item
|foot=1}}

{{edition|bedrock}}:
{{ID table
|edition=bedrock
|shownumericids=y
|showforms=y
|notshowbeitemforms=y
|generatetranslationkeys=y
|displayname=Dried Kelp
|spritetype=item
|nameid=dried_kelp
|id=270
|form=item
|foot=1}}

== History ==

{{History|java}}
{{History||1.13|snap=18w07a|[[File:Dried Kelp JE1.png|32px]] Added dried kelp.}}
{{History|||snap=18w08b|Dried kelp can now be used to craft [[dried kelp block]]s.}}
{{History||1.14|snap=19w03a|Placing dried kelp into the new [[composter]] has a 10% chance of raising the compost level by 1.}}
{{History|||snap=19w05a|Dried kelp now has a 30% chance of increasing the compost level in a composter.}}

{{History|bedrock}}
{{History||1.4.0|snap=beta 1.2.14.2|[[File:Dried Kelp BE1.png|32px]] Added dried kelp.}}
{{H||1.11.0|snap=beta 1.11.0.1|Dried kelp can now be used to fill up [[composter]]s.}}
{{History||1.17.10|snap=beta 1.17.10.20|[[FIle:Dried Kelp JE1.png|32px]] The texture of dried kelp has been changed to match ''Java Edition''.}}

{{History|console}}
{{History||xbox=TU69|ps=1.76|wiiu=Patch 38|[[File:Dried Kelp BE1.png|32px]] Added dried kelp.}}
{{History|foot}}

== Issues ==

{{issue list}}

{{Items}}

[[Category:Food]]
[[Category:Renewable resources]]

[[de:Getrockneter Seetang]]
[[es:Algas secas]]
[[fr:Algue séchée]]
[[ja:乾燥した昆布]]
[[ko:말린 켈프]]
[[lzh:乾海帶]]
[[nl:Gedroogde kelp]]
[[pl:Suszone wodorosty]]
[[pt:Algas secas]]
[[ru:Сушёная ламинария]]
[[th:สาหร่ายทะเลแห้ง]]
[[zh:干海带]]</li></ul>
13w18aComparators now give out a signal for Cauldrons and End Portal frames depending on their state.

Issues

Issues relating to "Redstone Comparator" are maintained on the bug tracker. Report issues there.

Trivia

  • The comparator does not re-strengthen a redstone signal. This means it can not be used for super-long instant circuits.
  • If placed every second block between redstone, they can endlessly carry a signal, at same speed than repeaters on first setting, without it losing power strength. Placing a non-transparent block at every corner allows it to bend without losing power. It is also possible to reduce the needed amount of comparators further (and thus improve the signal speed) by facing the comparators into solid blocks behind which redstone is placed
  • A redstone comparator outputs a strong signal. This does not mean it resets the signal strength like repeaters, but it means the signal can be picked up through a block without using a repeater (Like a repeater)
  • If you join up the redstone torches, an arrow is created which points to the redstone output. This arrow can also be seen as a red triangle on the Comparator, if one looks hard enough.

Gallery

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