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Observer

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This article is about the block that detects block updates. For the redstone mechanism, see block update detector.

An observer is a block that emits a quick redstone pulse from its back when the block or fluid directly in front of its "face" experiences a change.

Obtaining[]

Breaking[]

An observer requires a pickaxe to be mined. When mined without a pickaxe, it drops nothing.

Block Observer
Hardness 3
Tool
Breaking time[A]
Default 15
Wooden 2.25
Stone 1.15
Iron 0.75
Diamond 0.6
Netherite 0.5
Golden 0.4
  1. ↑ Times are for unenchanted tools as wielded by players with no status effects, measured in seconds. For more information, see Breaking § Speed.

Crafting[]

Ingredients Crafting recipe
Cobblestone +
Redstone Dust +
Nether Quartz

Usage[]

An observer is placed similarly to a piston. It observes the block that it is placed against. The texture of the detecting side is that of an observing face. As observers can detect the state of other observers, placing two adjacent observers, each watching the other, can make a fast and compact redstone clock. They send out a pulse.

Behavior[]

In Java Edition, an observer detects changes in its target's block states, or the breaking or placing of a block (i.e. changes in its block state, but not its block entity data). This means that changes like the age of crops can be detected because they are part of the block states.

In Bedrock Edition, an observer acts as a block update detector and detects anything that causes a block update.

The causes and propagation of block updates are different between Java Edition and Bedrock Edition. As a result, each can detect some kinds of changes that the other cannot. See the table below for a comparison.

When it detects something, the observer emits a redstone pulse of strong power at level 15 for 2 game ticks (1 redstone tick). The pulse can power redstone dust, a redstone comparator, a redstone repeater, or any mechanism component located at its opposite end.

In Java Edition, the pulse is emitted with a delay of 1 redstone tick. In Bedrock Edition, it is supposed to be delayed by 1 tick as well but is actually delayed 2 redstone ticks due to MCPE-15793, a bug causing redstone delays to be incorrect when components are activated by world changes (which, in the case of the observer in Bedrock Edition, is the only way it can be activated), as opposed to pure redstone components ticking. Its timing can also be incorrect due to MCPE-73342.

It also counts as a block update when the observer itself is moved by a piston. When this happens, an observer emits a pulse after being pushed or pulled, but not beforehand. This enables them to be used in flying machines.

Observers behave as both opaque and transparent blocks: they block light and allow mob spawning on top, but do not block opening chests below, do not cut off redstone wire, and cannot conduct redstone power.

Because observers in Java Edition detect changes in the block state, and not block updates, they can detect a wider range of phenomena than a block update detector (BUD) circuit in Bedrock Edition can detect (as some block state changes don't cause block updates). Observers in Bedrock Edition do detect block updates but not block state changes, and so they detect the exact same things that any other BUD would detect in that edition.

Limitations[]

Note blocks[]

The observer can be placed under note blocks to produce bass drum sounds.

Sounds[]

Java Edition:

SoundSubtitlesSourceDescriptionResource locationTranslation keyVolumePitchAttenuation
distance
Block brokenBlocksOnce the block has brokenblock.stone.breaksubtitles.block.generic.break1.00.816
Block placedBlocksWhen the block is placedblock.stone.placesubtitles.block.generic.place1.00.816
Block breakingBlocksWhile the block is in the process of being brokenblock.stone.hitsubtitles.block.generic.hit0.250.516
None[sound 1]Entity-DependentFalling on the block with fall damageblock.stone.fallNone[sound 1]0.50.7516
FootstepsEntity-DependentWalking on the blockblock.stone.stepsubtitles.block.generic.footsteps0.151.016
  1. ↑ a b MC-177082

Bedrock Edition:

SoundSourceDescriptionResource locationVolumePitch
BlocksOnce the block has brokendig.stone1.01.1-1.2
BlocksWhen the block is placeduse.stone1.01.2-1.25
BlocksWhile the block is in the process of being brokenhit.stone0.30.75
PlayersFalling on the block with fall damagefall.stone0.41.0
PlayersWalking on the blockstep.stone0.351.0
PlayersJumping from the blockjump.stone0.121.0
PlayersFalling on the block without fall damageland.stone0.221.0

Data values[]

ID[]

Java Edition:

NameIdentifierFormTranslation key
ObserverobserverBlock & Itemblock.minecraft.observer

Bedrock Edition:

NameIdentifierNumeric ID FormItem ID[i 1]Translation key
Observerobserver251Block & Giveable Item[i 2]Identical[i 3]tile.observer.name
  1. ↑ ID of block's direct item form, which is used in savegame files and addons.
  2. ↑ Available with /give command.
  3. ↑ The block's direct item form has the same id as the block.

Block states[]

See also: Block states

Java Edition:

Name Default value Allowed values Description
facingsouthdown
east
north
south
up
west		The direction the observer is observing. The same direction the player faces when placing the block.
poweredfalsefalse
true		True while the observer is observing a change and emitting a pulse.

Bedrock Edition:

NameMetadata Bits Default value Allowed valuesValues for
Metadata Bits		 Description
facing_direction
(Hidden)		0x1
0x2
0x4		00
1
2
3
4
5		0
1
2
3
4
5		The direction the observer is observing.
  • 0: Observer facing down
  • 1: Observer facing up
  • 2: Observer facing north
  • 3: Observer facing south
  • 4: Observer facing west
  • 5: Observer facing east
minecraft:facing_directionNot Supporteddowndown
east
north
south
up
west		UnsupportedThe direction the observer is observing.
powered_bit0x8falsefalse
true		0
1		True while the observer is observing a change and emitting a pulse.

History[]

Java Edition
November 24, 2012When announcing the upcoming 1.5 Redstone Update, Jeb mentions that changes to redstone logic may break existing BUD functionality, and therefore that block update detection may need to be implemented into the game in a more permanent, intentional form, rather than as a behavioral quirk.
1.1116w39a Added observers.
Note: the "arrow" texture on the top/bottom of observers is pointing the wrong direction (toward the input, rather than the output).
Observers act as a block update detector.
Observers emit pulses that lasted 1 game tick (0.5 redstone ticks) and have a signal strength of 1.
Observers can power blocks (like a redstone repeater).
Observers have no delay between detecting a block update and emitting a pulse, meaning that observers are essentially instant.
Observers are placed with the observing, or input, side facing the player.
16w41aObservers now emit 4 game tick (2 redstone ticks) pulses.[22]
The signal strength of observers has now been changed to 15.[23][24]
Observers *appear* to no longer strongly power blocks, and now emit only activation power, like a block of redstone (and this may be the intended behavior for this snapshot). However, in reality, they still strongly power blocks, but the blocks adjacent to those blocks aren't given block updates, causing buggy behavior.[25]
Observers are now placed with the output facing the player.[26][27]
A bug where observers would redirect redstone dust from all 4 directions has now been fixed.[28] (They are supposed to redirect dust only from their output side.)
16w42aThe developers have attempted to make observers no longer detect block updates happening to air blocks, in order to make observer behavior more predictable.[29] In the process, they have broken redstone mechanics a bit, so that the block update bug from the previous snapshot now affects redstone repeaters and redstone comparators, too.[30]
16w43a The model of observers has now been changed. The rotation of the "arrow" texture has now been fixed so it points in the correct direction.
General redstone mechanics for observers now work as they did before 16w42a, with the exception of the change named below.
Observers now output strong power like in 16w39a, except that they, as well as redstone repeaters and redstone comparators, no longer provide block updates to transparent blocks or air.
16w44aThe observer block update changes relating to redstone from 16w42a and 16w43a have now been fully reverted.
The behavior of observers has now been overhauled/redefined. Observers have now been changed from a block update detector to a block state change detector.
Observers have now been changed to detect when the block it was observing changed, its basic block state changed, or the block was placed/destroyed. (Note that it does not detect changes in the extended block state, e.g. changes that are not saved when the world is unloaded, such as the shape of a fence, or whether or not a repeater is locked.) This change has now made observer behavior much more predictable, as unexpected/invisible block updates would no longer trigger observers.[31]
Observers have now been changed to emit a 2 game tick (1 redstone tick) pulse when activated.[32]
Observers no longer output power instantly.[33]
pre1 The front and top texture of observers have now been changed.
The redstone output side of observers now blinks red when it outputs power.
1.1317w47aPrior to The Flattening, this block's numeral ID was 218.
Due to The Flattening, observers can now detect all block state changes, e.g. the changes in the shape of fences and redstone dust.
pre4Observers no longer produce a pulse when placed by hand.
1.1418w43a The textures of observers has now been changed.
1.1620w10aObservers can now support ladders and tripwire hooks.[34]
20w14aObservers now correctly detect when the status of the fence changes.
Pre-release 3 The back texture of activated observers has been changed.
1.1721w13aObservers now correctly detect when a grass block changes to dirt if a tree grows on top.
Pocket Edition Alpha
v0.15.0May 2, 2016Jeb tweeted that Daniel Wustenhoff is a working on a BUD block.[35]
Tommaso Checchi tweeted his "rejected graphics" for the observer block.[36]
build 1 Added observer blocks.
v0.15.3Observers are now placed like a piston and not a log.
Bedrock Edition
1.2.0beta 1.2.0.2 The front and top texture of observers have now been changed.
Observer blocks can now detect many more block changes.
The strength of the redstone pulse outputted by observer blocks has now been increased.
Observers no longer pulse twice when observing a retracting piston.
Opening and closing the command block screen no longer activates an observer block.
1.10.0beta 1.10.0.3 The textures of observers has now been changed.
1.16.0beta 1.15.0.53Observers no longer emit a pulse when they are first placed.
1.16.100beta 1.16.100.55Observers no longer get stuck in an active state when moved by pistons.
1.20.10beta 1.20.10.23Now uses the minecraft:facing_direction block state instead of facing_direction.
Legacy Console Edition
TU54CU44 1.52 Patch 241.0.4 Added observers.
1.90 The textures of observers has now been changed.
New Nintendo 3DS Edition
0.1.0 Added observers.

Issues[]

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

Trivia[]

  • The current observer texture was created because Jeb kept confusing the front with the back. He said it was inspired by the "rejected texture" created by Tommaso Checchi.[36][37]

Gallery[]

  • Development image of an observer from Jeb.
    Development image of an observer from Jeb.
  • The first image released of the new observer texture for Java Edition.
    The first image released of the new observer texture for Java Edition.

See also[]

References[]

  1. ↑ For example, a button cling on a block, when break the block that a button are clinging, that button will break and cause block update which can be detect by observer.
  2. ↑ For example, a mushroom are on light level of 13, according to Minecraft Wiki, at level 13 and above, mushroom will uproot unless on mycelium, podzol or nylium. When update the mushroom, that mushroom will break and cause block update which can be detect by observer.
  3. ↑ Another example, a wheat block are on light level of 0, according to Minecraft Wiki, at level 0 and below, wheat block will uproot. When update the wheat, that wheat will break and cause block update which can be detect by observer.
  4. ↑ For example, place 2 chorus plants on top of an end stone. When place a chorus plant on the side of the bottom one, that "bottom" chorus plant will break and cause block update which can be detect by observer.
  5. ↑ If a block get replaced by itself (with the same block states) by the /clone command, the observer will still be able to detect that. This does not happen for /setblock and /fill.[more information needed]
  6. ↑ If observer is placed using /setblock or /fill, that observer will be powered. This don't work for /clone.[more information needed]
  7. ↑ MC-107664
  8. ↑ MCPE-130935
  9. ↑ If an observer being pushed/pulled by a (sticky) piston, that observer will also powered.[more information needed]
  10. ↑ In Java Edition the game rule snowAccumulationHeight must be larger than 1.
  11. ↑ The change of quasi-connected state usually coincides with some other block state change for these mechanisms, such as activating to dispense an item, or the piston head extending/retracting. Therefore, this effect is only noticeable when a dropper or dispenser "deactivates" by losing its quasi-connected status when the redstone power source is turned off. To demonstrate, use a lever to power a redstone repeater that quasi-connects to a dropper. Monitor the dropper with an observer. Turn the lever on. The dropper will drop an item and the observer will trigger. Turn the lever off. The dropper will not do anything, but the observer will trigger again because it detects the dropper's change in quasi-connected state.
  12. ↑ When the fluid source block is removed, all of the fluid flowing from the source will also be removed and cause a block update.
  13. ↑ In Bedrock Edition, rabbits do not eat carrot crops; see MCPE-113321 and MCPE-131980.
  14. ↑ In Bedrock Edition, the death of a coral fan cannot happen under normal circumstances — it happens the very next tick after the coral fan is placed, so the observer will already be reading the placement or water removal update, and coral fans placed using commands are waterlogged — but if lag is used to make the unwaterlogging and death events happen separately, the observer will detect both. For coral, the death also happens too fast for the observer to detect it separate from the placement or water removal, but a non-waterlogged coral can be placed using commands. Coral blocks take multiple seconds to die, and removing water next to the coral block does not activate the observer anyway, so they can be detected under normal circumstances.
  15. ↑ This event cannot normally happen, but if commands are used to place a wet sponge in the nether, the sponge will dry when it recieves a random tick.‌[Bedrock Edition only] In Java Edition, sponges in the Nether always stay wet.
  16. ↑ The disarmed‌[JE only] or disarmed_bit‌[BE only] block state cannot change without also detaching the tripwire, so this event cannot happen in isolation.
  17. ↑ In Bedrock Edition, observers detect when a sculk shrieker stops shrieking, but not when it starts shrieking.
  18. ↑ In Bedrock Edition, placing a pumpkin or melon next to a corresponding stem does not cause the stem to attach.
  19. ↑ In Bedrock Edition, using bone meal on a coral block does not create sea pickles, due to MCPE-171383.
  20. ↑ Grass, tall grass, 1-block-tall flower, seagrass, tall seagrass, coral, (wall) coral fan, moss carpet, azalea, flowering azalea, roots, fungus, nether sprouts, twisting vine, and pink petals.
  21. ↑ Both under the sapling and the area around the sapling.
  22. ↑ MC-107410
  23. ↑ MC-107783
  24. ↑ MCPE-17439
  25. ↑ MC-108696
  26. ↑ MC-107934
  27. ↑ MCPE-17321
  28. ↑ MC-107795
  29. ↑ MC-107730
  30. ↑ MC-108897
  31. ↑ MC-107760
  32. ↑ MC-108697
  33. ↑ MC-107623
  34. ↑ MC-146824
  35. ↑ "Hype train! @darngeek is working on a device that acts as a proper BUD block in MC:PE (PC eventually), currently called "Observer"" – @jeb_ (Jens Bergensten) on X, May 2, 2016
  36. ↑ a b "Here's my rejected graphics for the Observer, because @darngeek has no artistic sensibility" – @_tomcc (Tommaso Checchi) on X, May 2, 2016
  37. ↑ "I kept confusing myself which side was front and back, so here's something inspired by the works of @_tomcc http://i.imgur.com/IK2d8m2.png" – @jeb_ (Jens Bergensten) on X, November 7, 2016
  1. ↑ a b When deactivated, the sculk sensor's and the calibrated sculk sensor's "sculk_sensor_phase" block stage is converted from "active"->"cooldown"->"inactive". However, this happens so fast that observer can't detect it, so that isn't counted.

External Links[]

Redstone 

View at: Template:Redstone/content [edit]
Blocks
Biota
Wood/Hypha
Plant
Fungus
Algae
Fauna
Fauna/Related
Sculk
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BE & edu only
Utility
Interactable
Utilizable
Redstone/Mechanical
Education Edition only
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Removed
Java Edition only
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