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Minecraft Wiki
Observer JE4 BE3.png
Observer JE3.png




Blast resistance






Yes (64)





Data values

PC: dec: 218 hex: DA bin: 11011010
PE: dec: 251 hex: FB bin: 11111011



An observer is a block that emits a redstone signal when an adjacent block is updated.


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

Block Observer
Hardness 3.5
Breaking time[note 1]
Hand 17.5
Wooden 2.65
Stone 1.35
Iron 0.9
Diamond 0.7
Golden 0.45
  1. Times are for unenchanted tools in seconds. For more information, see Haste § Instant mining.


Ingredients Crafting recipe Description
Cobblestone +
Redstone +
Nether Quartz

Computer and Pocket editions only


An observer is placed similarly to a piston, and will observe the block that it is placed against. Unlike many redstone components, the 'face' (detection side) points away from the player who placed the block.

In Pocket Edition the observer block texture has two dots which are at opposite ends when the block is placed. The smaller dot outputs a redstone signal whilst the bigger dot detects the block update. In the Computer Edition, the texture of the detection end is that of an 'observing' face.


In the Computer Edition, an observer will detect changes in its target's block ID or data value, or the breaking or placing of a block. (Changes in its basic block state, but not its extended/actual block state.) This means that changes like the age of crops will be detected, since they are part of the basic block state that is converted to metadata when the world is saved; however, changes like the shape of a fence will not be detected, since those are part of the extended block state, which is not saved when the world is saved.

In the Pocket Edition, an observer acts as a block update detector, and detects anything that causes a block update in that edition. (Note that what causes a block update and how they propagate is very different between the Computer Edition and the Pocket Edition.)

When it detects something, the observer emits a redstone pulse, powering redstone dust, redstone comparators and redstone repeaters, as well as powering mechanism components located at its opposite end with power level 15 for 2 game ticks (1 redstone tick). In the Java/Computer Edition, the observer outputs strong power, and can strongly power blocks like a redstone repeater.

In Pocket Edition, the observer emits the same kind of pulse as the Computer Edition observer, except that it does not strongly power blocks, the pulse lasts for 4 game ticks (2 redstone ticks), and the observer outputs activation power only, similar to a block of redstone.

It also counts as a block change/block state change/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.

Observers behave as a transparent block even though they block light. This means they cannot be powered with an external power source, nor power themselves with their own output.

Because observers in the Computer Edition detect changes in the basic block state, and not block updates, they can detect a wider range of phenomena than a block update detector (BUD) circuit in the Computer Edition can detect (as some block state changes don't cause block updates), though it has different limitations. Observers in the Pocket Edition do detect block updates, so they function just like any other block update detector would function in that edition.


Block state change: Detected
in PE
in PC
Locking / unlocking a redstone repeater No No
Changes to the data value of fire that signifies flammable surfaces surrounding fire No No
Changes in the shape of walls, fences, iron bars, glass panes, stairs, tripwire, redstone dust, vines, melon stem or pumpkin stem No No
A grass, mycelium or podzol block becoming snowy or not snowy No No
Changes to inventory of any blocks that comparators measure as containers No No
Activating / deactivating a beacon No No
Playing a note block No No
Opening and closing shulker boxes, chests & ender chests No No
Success of a command block n/a No
Teleporting something by the end gateway Yes No
Adding / removing contents from a flower pot Yes No
The opening/closing of the top part of a door by hand, as opposed to by redstone power. Yes No
Powering / depowering of activator rails No Yes
Inverting / deinverting a daylight sensor No Yes
Activation of a dropper or dispenser No Yes
Activation / deactivation of redstone ore, or of a redstone torch No Yes
A piston (not the head) extending or contracting No Yes
Locking / unlocking a hopper No Yes
Spread of grass to dirt, or decay of grass into dirt No Yes
Growth of nether wart, forced growth of cocoa pods by bone meal, or growth of vines into empty space No Yes
Aging of saplings, sugar cane or fire No Yes
Farmland going through its hydration stages No Yes
Moving bottles to / from a brewing stand No Yes
All other block / block state changes Yes Yes

Data values[]

Block data[]

See also: Data values and Pocket Edition data values
DV Description
0 Facing down
1 Facing up
2 Facing south
3 Facing north
4 Facing east
5 Facing west

Block state[]

See also: Block states
Name Value Description
The direction the observer is observing. The same direction the player faces, when placing the block.
True while the observer is observing a change and emitting a pulse.


  • When moved by a piston, an observer sends a 2 game tick (1 redstone tick) pulse after being moved, which makes it useful for slime block flying machines. (Note: in Pocket Edition, it's a 4 game tick (2 redstone tick) pulse.)
  • The current Observer texture was created because Jeb kept confusing which side was front/back. He said it was inspired by the "rejected texture" created by Tommaso Checchi.[1][2]


Official release
1.1116w39aAdded observer block. When first added, the observers acted as a block update detector, and would emit pulses that lasted 1 game tick (0.5 redstone ticks) and had a signal strength of 1. The observer could also power blocks (like a repeater). It also had no delay between detecting a block update and emitting a pulse, meaning that observers were essentially instant. They were also placed with the observing, or input, side facing the player.
Note: the "arrow" texture on the top/bottom of the observer was pointing the wrong direction (towards the input, rather than the output). This was not noticed by most people, though, since the observer in Pocket Edition had (and as of 1.0.0 still has) a texture bug where the top & side textures wouldn't rotate properly (except the output/input sides), causing the arrow texture to always point in the same direction.
16w41aObservers were changed to emit 4 game tick (2 redstone tick) pulses[7], and their signal strength was changed to 15.[8][9]
Observers *appear* to no longer strongly power blocks, and now only emit activation power, like a block of redstone. (And this may have been 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 weird and buggy behavior.[3]
Observers are now placed with the output facing the player.[4][5]
Fixed a bug where observers would redirect redstone dust from all 4 directions.[6] (They are only supposed to redirect dust from their output side.)
16w42aThe devs attempted to make observers no longer detect block updates happening to air blocks, in order to make observer behavior more predictable.[10] In the process they broke redstone mechanics a bit, so that the block update bug from the previous snapshot now affected repeaters & comparators, too.[11]
16w43aObserver JE3.png Fixed the rotation of the "arrow" texture so it would point in the right direction.
General redstone mechanics 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 repeaters & comparators, no longer provide block updates to transparent blocks or air.
16w44aThe block update changes relating to redstone from 16w42a & 16w43a were fully reverted.
Observer behavior was overhauled/redefined. The observer changed from a block update detector to a block state change detector. Observers were 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, AKA 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 made observer behavior much more predictable, as unexpected/invisible block updates would no longer trigger observers.[12]
Observers were changed to emit a 2 game tick (1 redstone tick) pulse when activated.[13]
Observers no longer output power instantly.[14]
1.11-pre1Observer JE4 BE3.png Changed front (detecting side) texture to be an 'observing face'. The "arrow" texture on the top/bottom of the observer was also modified.
The redstone output side now blinks red when it outputs power.
Pocket Edition Alpha
0.15.0May 2, 2016Jeb tweeted that Daniel Wustenhoff is a working on a BUD block.[16]
Observer (front texture) pBE20160502.png
Tommaso Checchi tweeted his "rejected graphics" for the block.[15]
build 1Observer JE3.png Added observer block.
0.15.3Observers are now placed like a piston and not a log.


Issues relating to “Observer” are maintained on the issue tracker. Report issues there.


See also[]