Redstone components

Redstone components are the blocks used to build redstone structures. Redstone components include power components (such as redstone torches, buttons, and pressure plates), transmission components (such as redstone dust and redstone repeaters), and mechanism components (such as pistons, doors, and redstone lamps).

This article assumes familiarity with the basics of redstone structures; for details on terms and concepts, see redstone basics. This article also limits its discussion of each component to its role in redstone structures; for full details about a component, see the main article for the block.

Power components
Power components create redstone signals, either permanently or in response to player, mob, and environmental activity.

Block of redstone
A block of redstone is used to provide a constant power source that can be moved by pistons.


 * Activation


 * A block of redstone is always ON.


 * Effect


 * A block of redstone powers any adjacent redstone dust (including beneath and on top of it), and any adjacent redstone comparator or redstone repeater facing away from it. It also activates any adjacent mechanism component (including above or below).


 * A block of redstone has no effect on adjacent opaque blocks.

Button
A button is used to generate a pulse. A button may be of two types: wooden or stone.


 * Placement


 * A button can be attached to the side of most opaque blocks. If the attachment block is removed, the button will "pop" off as an item.


 * Activation


 * A player can turn a stone or wooden button ON by right-clicking it, and a wooden button can also be turned ON by a fired arrow. A stone button stays ON for 10 ticks (1 second), while a wooden button stays ON for 15 ticks (1.5 seconds) or, if turned ON by a fired arrow, until the arrow despawns after one minute or is picked up.


 * Effect


 * While activated, a button and its attachment block both power any adjacent redstone dust (including beneath the button, or beneath or on top of the block), and any adjacent redstone comparator or redstone repeater facing away. They also activate any adjacent mechanism component (including above or below).

Daylight sensor
A daylight sensor is used to detect the "time" of the Minecraft day.


 * Activation


 * A daylight sensor, if exposed to the sky ("sl" greater than 0), turns ON at dawn and turns OFF at night. A daylight sensor blocked from the sky ("sl" equals 0) turns ON at night and turns OFF at dawn.


 * Effect


 * While activated, a daylight sensor powers any adjacent redstone dust (including beneath it), and any adjacent redstone comparator or redstone repeater facing away from it, at a power level proportionate to the height of the sun or moon in the sky. It also activates any adjacent mechanism component (including above or below).


 * A daylight sensor has no effect on adjacent opaque blocks.

Detector rail
A detector rail is used to detect the passage of a minecart.


 * Placement


 * A detector rail can be attached to the top of any opaque block, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the detector rail will "pop" off as an item.


 * When placed, a detector rail will configure itself to line up with adjacent rails, powered rails, and detector rails, as well as such adjacent rails one block up. If there are two such adjacent rails on non-opposite sides, or three or more such adjacent rails, a detector rail will line up in the east-west direction. If there are no such adjacent rails, a detector rail will line up in the north-south direction. If a rail it would line up with is one block up, a detector rail will slant upwards towards it (with multiple options to slant upwards to, a detector rail "prefers", in order: west, east, south, and north). Other configurations can be created by placing and removing various rail.


 * Activation


 * A detector rail turns ON when a minecart passes over it, and turns OFF when it leaves.


 * Effect


 * While activated, a detector rail and its attachment block (unless attached to a slab or stairs) both power any adjacent redstone dust (including beneath the block), and any adjacent redstone comparator or redstone repeater facing away. They also activate any adjacent mechanism component (including above or below).

Lever
A lever is used to switch circuits on or off, or to permanently power a block.


 * Placement


 * A lever can be attached to the top, side, or bottom of most opaque blocks, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the lever will "pop" off as an item.


 * Activation


 * A player can turn a lever ON or OFF by right-clicking it.


 * Effect


 * While activated, a lever and its attachment block (unless attached to a slab or stairs) both power any adjacent redstone dust (including beneath the lever, or beneath or on top of the block), and any adjacent redstone comparator or redstone repeater facing away. They also activate any adjacent mechanism component (including above or below).

Pressure plate
A pressure plate is used to detect mobs, items, and other entities. A pressure plate may be of two types: wooden or stone.


 * Placement


 * A pressure plate can be attached to the top of any opaque block, or to the top of a fence, nether brick fence, an upside-down slab or upside-down stairs. If the attachment block is removed, the pressure plate will "pop" off as an item.


 * Activation


 * A pressure plate turns ON when an entity (mob, item, etc.) crosses or falls on it, and turns OFF when the entity leaves or is removed. A stone pressure plate is turned ON only by mobs (including players), while a wooden pressure plate is turned ON by mobs, items, and fired arrows. A wooden pressure plate turned ON by an item or fired arrow won't turn OFF until the item or arrow is picked up or despawns (after one minute for a fired arrow, or up to five minutes for an item).


 * Effect


 * While activated, a pressure plate and its attachment block (unless attached to a fence, nether brick fence, slab, or stairs) both power any adjacent redstone dust (including beneath the block), and any adjacent redstone comparator or redstone repeater facing away. They also activate any adjacent mechanism component (including above or below).


 * Considerations


 * A pressure plate is not solid (it is not a barrier to entity movement). Usually a block under a pressure plate provides a solid barrier underneath it (for mobs to walk across, items to fall on, etc.), but when a pressure plate is placed on a block with a small collision mask, like a fence or nether brick fence, it is possible for entities to move through the pressure plate while still activating it. Thus, a pressure plate on a fence can be used to detect entities without stopping them (more compactly than a tripwire circuit).

Redstone torch
A redstone torch is used to power circuits, invert signals, and transmit power vertically.


 * Placement


 * A redstone torch can be attached to the top or side of any opaque block, or to the top of cobblestone wall, fence, glass, nether brick fence, an upside-down slab or upside-down stairs. If the attachment block is removed, the redstone torch will "pop" off as an item.


 * Activation


 * A redstone torch stays ON until the block it is attached to is powered.


 * Effect


 * While activated, a redstone torch and any opaque block above it both power any adjacent redstone dust (including beneath the redstone torch, or on top of the block), and any adjacent redstone comparator or redstone repeater facing away. They also activate any adjacent mechanism component (including above or below).


 * A redstone torch does not affect the block it is attached to (even if it is a mechanism component).


 * Considerations


 * A redstone torch will "burn-out" (go dark and stop providing power) when it is forced to flicker on and off too quickly (by powering and de-powering the block it's attached to). After burning-out, a redstone torch will re-light when it receives a redstone update, or randomly after a short time.


 * One way to cause a burn-out is with a short-circuit – using a torch to turn itself off, which then allows the torch to turn back on, etc. For example, if you place redstone dust on top of a block and a redstone torch on its side, then put another block above the torch, the torch will power the top block, which will turn on the adjacent redstone dust, which will power the block below it, turning the torch off – this will cause the redstone torch to flicker and burn-out. When you need to put a torch under a block next to redstone dust, don't attach the torch to the block supporting the dust or you'll get burn-out.

Trapped chest
A trapped chest is used to detect player access of its contents.


 * Activation


 * A trapped chest is turned ON by one or more players accessing its contents.


 * Effect


 * While activated, a trapped chest and any opaque block beneath it both power any adjacent redstone dust (including beneath the block), and any adjacent redstone comparator or redstone repeater facing away, at a power level equal to the number of players accessing the trapped chest's contents (maximum 15). They also activate any adjacent mechanism component (including above or below).

Tripwire hook
A tripwire hook is used to detect mobs, items, and other entities over a large area.


 * Placement


 * A tripwire hook can be attached to the side of most opaque blocks. If the attachment block is removed, the tripwire hook will "pop" off as an item.


 * In order to function correctly, a tripwire hook must be part of a "tripwire circuit": a straight line of blocks consisting of an opaque block with a tripwire hook attached to it, a "tripwire line" (one or more blocks of tripwire), and a second tripwire hook attached to another opaque block.


 * To place tripwire, right-click on an adjacent block with a string. Tripwire can be placed "on the ground" or "in the air", and will only form a valid tripwire line if all the tripwire is of the same type. Tripwire is considered on the ground if placed on any opaque block, or on a block of redstone, a hopper, an upside-down slab, or an upside-down stairs. Tripwire is considered in the air if placed on any other block, or above air. Tripwire on the ground has a short hitbox (1/8 block tall), while tripwire in the air has a taller hitbox (1/2 block tall).


 * If the attachment block under ground tripwire is removed, the tripwire will "pop" off as string.


 * A tripwire circuit is placed correctly when the tripwire hooks are fully extended and the tripwire line runs continuously between the tripwire hooks. Tripwire lines from separate tripwire circuits can be placed next to each other (in parallel), above each other, and can even intersect each other.


 * Activation


 * A tripwire hook turns ON when an entity (mob, item, etc.) crosses or falls on the hook's tripwire line (but not the tripwire hook), and turns OFF when all entities leave or are removed from the tripwire line. A tripwire hook also turns ON for 5 ticks when any of its tripwires are destroyed, except when using shears to "cut" the tripwire. Breaking the tripwire hook, or the block it is attached to, does not generate a pulse.


 * Effect


 * While activated, a tripwire hook and its attachment block both power any adjacent redstone dust (including below the tripwire hook, or beneath or above the block), and any adjacent redstone comparator or redstone repeater facing away. They also activate any adjacent mechanism component (including above or below).


 * Tripwire provides no power itself.

Weighted pressure plate
A weighted pressure plate is used to measure the number of items on top of it. A weighted pressure plate may be of two types: light (gold) or heavy (iron).


 * Placement


 * A weighted pressure plate can be attached to the top of any opaque block, or to the top of a fence, nether brick fence, an upside-down slab or upside-down stairs. If the attachment block is removed, the weighted pressure plate will "pop" off as an item.


 * Activation


 * A weighted pressure plate is turned ON by one or more items on top of it.


 * Effect


 * While activated, a weighted pressure plate and its attachment block (unless attached to a fence, nether brick fence, slab, or stairs) both power any adjacent redstone dust (including beneath the block), and any adjacent redstone comparator or redstone repeater facing away, at a power level proportional to the entities on the weighted pressure plate. They also activate any adjacent mechanism component (including above or below).

Transmission components
Transmission components propagate signals and pulses from power components to mechanism components. Complex effects can also be produced by allowing a signal to affect itself or its circuit.

Redstone comparator
A redstone comparator is used to compare or subtract two signals, or to measure how full a container is.


 * Placement


 * A redstone comparator can be attached to the top of any opaque block, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the redstone comparator will "pop" off as an item.


 * A redstone comparator has a front and a back &mdash; the arrow points from the back to the front. The comparator takes a signal from its back as its input, and outputs a signal to the block in front of it, but can also be affected by signals from its sides (see below).


 * A redstone comparator has two modes. Right-clicking a redstone comparator changes it between comparison mode (front torch down/off) and subtraction mode (front torch up/on).


 * Activation


 * A redstone comparator is turned ON by any powered component at its back, or by a non-empty container (as well as by container minecarts on a detector rail, a command block that has run its last command successfully, a cauldron containing water, an end portal frame with an eye of ender, or a jukebox with a record) either at its back or separated from its back by an opaque block. It is not affected by blocks beneath it or above it, but its signal strength can be modified by signals from its sides (see below).


 * Effect


 * A powered redstone comparator turns ON redstone dust, a correctly-facing redstone comparator or redstone repeater, or a mechanism component in front of it, or strongly powers an opaque block in front of it – all at the same power level as its input signal (unless modified by a side signal, see below). It has no effect on blocks in other adjacent positions (including the block beneath it).


 * The output of a redstone comparator can be affected by a signal provided from its side by a transmission component (redstone dust, redstone repeater, or another redstone comparator only):
 * In comparison mode, a redstone comparator only propagates its input signal if the input signal is greater than the side signal, and outputs no signal if not.
 * In subtraction mode, a redstone comparator outputs a power level equal to the power level of the input signal minus the power level of the side signal.


 * A redstone comparator activated by a container outputs a power level in proportion to how full the container is (rounded up, so a single item in a container will produce a power level of at least 1). A container's fullness is measured by stacks: for example, a single shovel (a non-stackable item), 16 signs, or 64 sticks are all considered to be full stacks and count equally towards a container's fullness.


 * The Comparator Output Table (right) shows the minimum stacks ("s") plus items ("i") required to produce a specific power level from a container. For example, to get power level 5 from a hopper, put 1 stack plus 28 items in the hopper. Divide items by 4 and round up for items with a stack maximum of 16. The values for the chest, dispenser, furnace and hopper apply to minecarts with those components as well (when on a detector rail).


 * Some blocks (such as crafting tables, enchantment tables, etc.) can hold items temporarily while the player uses the block's interface, but the items will be dropped if the player exits the interface with items still inside. Other blocks (such as beacons) can only consume items put in them. Putting items in these blocks will not activate a redstone comparator, even temporarily.

Redstone dust
Redstone dust is used to transmit power.


 * Placement


 * Redstone dust is placed by right-clicking with redstone ("redstone" is the item, "redstone dust" is the block). Redstone dust can be attached to the top of any opaque block, or to the top of glowstone, an upside-down slab or upside-down stairs. If the attachment block is removed, the redstone dust will "pop" off as an item.


 * When placed, redstone dust will configure itself to point towards adjacent redstone dust (at the same level or one level up or down), correctly-facing redstone repeaters and redstone comparators, and power components. If there is only one such neighbor, redstone dust will form a line pointing towards and away from that one neighbor (which can cause it to point towards blocks it wouldn't normally point towards). If there are multiple such neighbors, redstone dust will form either a line, an "L", a "T", or a "+". If there are no such neighbors, redstone dust will form a large directionless dot. Redstone dust won't automatically configure itself to point towards adjacent mechanism components, it must be arranged to do so.


 * When two redstone dusts are placed vertically diagonally (one block over and one up, or one over and one down), the lower dust will appear to "crawl" up the side of the higher block to join the other dust. This linking can be "cut" by an opaque block above the lower dust, which prevents the two dusts from connecting visually or transmitting power to each other. If the higher dust is on an upside-down slab or upside-down stairs, the higher dust will configure itself to point towards the lower dust (and other adjacent dust), but the lower dust will not configure itself to point towards the higher dust (including not appearing to "crawl" up the side of the slab or stairs).


 * The directions in which redstone dust configures itself can affect whether it powers adjacent opaque blocks and mechanisms.


 * Activation


 * Redstone dust can be turned ON by any adjacent power component, redstone repeater pointing at it, or strongly-powered opaque block. Redstone dust can also be turned ON by other adjacent powered redstone dust, but the power decreases with distance from a strongly-powered block. Redstone dust can transmit power up to 15 blocks.


 * Redstone dust can transmit power diagonally upwards to dust on an upside-down slab or upside-down stairs, but not diagonally downwards from an upside-down slab or upside-down stairs.


 * Effect


 * Powered redstone dust turns ON any mechanism component it is configured to point at. It will weakly-power an opaque block it is pointing at, or under it (supporting it).

Redstone repeater
A redstone repeater is used to transmit power, re-strengthen redstone dust signals weakened by distance, delay a signal, and to give direction to redstone signal propagation.


 * Placement


 * A redstone repeater can be attached to the top of any opaque block, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the redstone repeater will "pop" off as an item.


 * A redstone repeater has a front and a back – the arrow points from the back to the front. The repeater only reacts to signals from the block behind it and only propagates signals to the block in front of it (in the direction of the arrow). It also has an adjustable delay that can be set from 1 to 4 ticks by right-clicking it.


 * Activation


 * A redstone repeater is turned ON by any powered component at its back and is unaffected by the powered state of any block beside, above, below, or in front of it (but see below about "locking" a repeater).


 * Effect


 * A powered redstone repeater turns ON redstone dust or a mechanism component in front of it, or strongly powers an opaque block in front of it. It has no effect on the blocks under, above, beside, or behind it.


 * A redstone repeater not only "repeats" a signal (re-strengthens it for transmission), it also delays it by 1 to 4 ticks. A redstone repeater will also increase the duration of any pulse shorter than its delay to match the duration of its delay.


 * A redstone repeater can be "locked" by powering it from the side with another redstone repeater or with a redstone comparator. A locked repeater will not change its output state until unlocked, even if its input changes. A repeater locked by another repeater (but not by a comparator) will display its locked status with a bedrock bar.

Mechanism components
Mechanism components are blocks which react to redstone power by affecting the environment – by moving themselves or other entities, by producing light, sound, or explosions, etc.


 * Activation


 * All mechanism components are turned ON by:
 * an adjacent active power component (Exceptions: a redstone torch will not turn ON a mechanism component it is attached to, and a piston is not activated by a power component directly in front of it unless that component also powers the piston by connectivity)
 * an adjacent powered opaque block (strongly-powered or weakly-powered)
 * a powered redstone repeater or redstone comparator facing the mechanism component
 * powered redstone dust configured to point at the mechanism component (or on top of it, for opaque mechanism components); a mechanism component is not turned ON by adjacent powered redstone dust which is not configured to point at it.


 * Quasi-Connectivity


 * In addition to the methods above, dispensers, droppers, and pistons can also be turned ON if one of the methods above would activate a mechanism component in the block above the component, even if there is no mechanism component there (even if the block above the component is air or a transparent block), but only when the component receives a block update (including a redstone update within two blocks of the component). This rule is often simplified to saying that the components can be powered by blocks diagonally above or two blocks above, but other methods of activation by connectivity exist (see image to the right). This method of activation is also known as "connectivity", "piston connectivity" (as it originated with pistons), or simply "indirect power".


 * Activation vs. Powered


 * For opaque mechanism components (command blocks, droppers, dispensers, note blocks, redstone lamps, and TNT), it's important to make a distinction between a mechanism component being activated (so that it performs an action) and being powered (so that a redstone signal could be drawn from it by a transmission component). Any method of powering a mechanism component (such as a redstone torch underneath it) will also activate it, but some activation methods (such as a redstone torch next to or above a mechanism component) won't actually power the component (following the usual rules for power components).

Activator rail
An activator rail is used to activate a minecart.


 * Placement


 * An activator rail can be attached to the top of any opaque block, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the activator rail will "pop" off as an item.


 * When placed, an activator rail will configure itself to line up with adjacent rails, activator rails, powered rails, and detector rails, as well as such adjacent rails one block up. If there are two such adjacent rails on non-opposite sides, or three or more such adjacent rails, an activator rail will line up in the east-west direction. If there are no such adjacent rails, an activator rail will line up in the north-south direction. If a rail it would line up with is one block up, an activator rail will slant upwards towards it (with multiple options to slant upwards to, an activator rail "prefers", in order: west, east, south, and north). Other configurations can be created by placing and removing various rail.


 * Activation


 * In addition to the methods above, an activator rail can also be activated by other adjacent activated activator rail. Activator rail can transmit activation up to 9 rails (the first originally-activated activator rail, and up to eight additional activator rails). Activation transmitted in this way cannot power any redstone components except activator rail.


 * Effect


 * An activator rail affects certain minecarts passing over it. The effects vary with the type of minecart activated:
 * A minecart with command block will execute its command every 2 redstone ticks (5 times per second).
 * A minecart with hopper will be deactivated by an active activator rail (it will stop sucking up items in its path, or transferring items to containers as it passes them), and re-activated by an inactive activator rail.
 * A minecart with TNT will be ignited by an active activator rail.
 * Other minecarts are not affected by an activator rail.

Command block
A command block is used to execute a server command. Command blocks can only be obtained with the command.


 * Placement


 * After being placed, the player can set the command to be executed by right-clicking on the command block.


 * Effect


 * When activated, a command block executes its defined command once. To make a command block constantly execute its command, it must be run on a clock circuit.


 * Like other mechanism components, an already-activated command block will not respond to other redstone signals. To make a command block execute its defined command more than once it must be deactivated and re-activated repetitively.

Dispenser
A dispenser is used to interact with the environment with items.


 * Activation


 * See Quasi-Connectivity above.


 * Effect


 * When activated, a dispenser ejects one item. If multiple slots are occupied by items, a random occupied slot will be chosen for ejection.


 * If the dispenser is facing a container, the ejected item will be transferred into the container. Otherwise, the effects of being activated vary with ejected item:


 * {| class="collapsible wikitable"

! colspan=2 | Dispenser Behavior ! Item ! Effect
 * Equips on a player within a one-block distance (any armor, made from any material)
 * Fired in the direction the dispenser is facing, as if the player had right-clicked a bow in their inventory
 * Placed as entity (i.e., a right-clickable vehicle) in the block the dispenser is facing, if the dispenser is facing water or an empty block above water &mdash; otherwise dropped (see below)
 * Increments the growth stage of carrots, cocoa pods, crops, melon stems, potatoes, pumpkin stems, and saplings the dispenser is facing; grows grass, dandelions, and roses, if the dispenser is facing a grass block; grows a huge brown mushroom if facing a brown mushroom
 * Fired in the direction the dispenser is facing, as if the player had right-clicked the item in their inventory
 * Collects lava or water the dispenser is facing (replacing the empty bucket in the dispenser with a lava or water bucket) &mdash; otherwise dropped (see below)
 * Ignites the block the dispenser is facing; reduces the remaining durability of the used flint and steel
 * Places lava or water in the block the dispenser is facing (replacing the lava or water bucket in the dispenser with an empty bucket), if the block the dispenser is facing is one that the player could use a lava or water bucket on (e.g., air, flowers, grass, etc.) &mdash; otherwise dropped (see below)
 * Placed as entity (i.e., a right-clickable vehicle) in the block the dispenser is facing, if the dispenser is facing a type of rails &mdash; otherwise dropped (see below)
 * Places and ignites TNT in the block the dispenser is facing
 * Others
 * Dropped: ejected towards the block the dispenser is facing, as if the player had used the Drop control (default )
 * }
 * Fired in the direction the dispenser is facing, as if the player had right-clicked the item in their inventory
 * Collects lava or water the dispenser is facing (replacing the empty bucket in the dispenser with a lava or water bucket) &mdash; otherwise dropped (see below)
 * Ignites the block the dispenser is facing; reduces the remaining durability of the used flint and steel
 * Places lava or water in the block the dispenser is facing (replacing the lava or water bucket in the dispenser with an empty bucket), if the block the dispenser is facing is one that the player could use a lava or water bucket on (e.g., air, flowers, grass, etc.) &mdash; otherwise dropped (see below)
 * Placed as entity (i.e., a right-clickable vehicle) in the block the dispenser is facing, if the dispenser is facing a type of rails &mdash; otherwise dropped (see below)
 * Places and ignites TNT in the block the dispenser is facing
 * Others
 * Dropped: ejected towards the block the dispenser is facing, as if the player had used the Drop control (default )
 * }
 * Places lava or water in the block the dispenser is facing (replacing the lava or water bucket in the dispenser with an empty bucket), if the block the dispenser is facing is one that the player could use a lava or water bucket on (e.g., air, flowers, grass, etc.) &mdash; otherwise dropped (see below)
 * Placed as entity (i.e., a right-clickable vehicle) in the block the dispenser is facing, if the dispenser is facing a type of rails &mdash; otherwise dropped (see below)
 * Places and ignites TNT in the block the dispenser is facing
 * Others
 * Dropped: ejected towards the block the dispenser is facing, as if the player had used the Drop control (default )
 * }
 * Places and ignites TNT in the block the dispenser is facing
 * Others
 * Dropped: ejected towards the block the dispenser is facing, as if the player had used the Drop control (default )
 * }
 * Dropped: ejected towards the block the dispenser is facing, as if the player had used the Drop control (default )
 * }


 * Considerations


 * A dispenser is an opaque block, so powering it directly can cause adjacent mechanism components (including other dispensers) to activate as well.

Door
A door is used to control or prevent the movement of mobs, items, boats, and other entities. A door may be of two types: a wooden door can be opened and closed by redstone power or by a player right-clicking on it, while an iron door can only be opened and closed by redstone power.


 * Placement


 * A door can be attached to the top of most opaque blocks, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the door will "pop" off as an item.


 * A door is placed on the edge of the block facing the player. By default the door's hinge will be on the left side, but another door or block can force the hinge to the right side.


 * Effect


 * While activated, a door re-positions to the other side of its hinge, allowing movement through its former position and denying movement through its current position. When activated, any entities on the door will fall.


 * A door doesn't actually "move" (the way a piston arm or a pushed block moves), it simply disappears from one side and re-appears on another, so it won't push entities as it "opens".

Dropper
A dropper is used to eject items or push them into containers (including other droppers).


 * Placement


 * A dropper can be placed so that its output faces in any direction.


 * Activation


 * See Quasi-Connectivity above.


 * Effect


 * When activated, a dropper ejects one item. If multiple slots are occupied by items, a random occupied slot will be chosen for ejection.


 * If the dropper is facing a container, the ejected item will be transferred into the container. Otherwise, the item is ejected in the direction the dropper is facing, as if the player had used the Drop control.


 * Considerations


 * A dropper is an opaque block, so powering it directly can cause adjacent mechanism components (including other droppers) to activate as well.

Fence gate
A fence gate is used to control or prevent the movement of mobs, items, boats, and other entities.


 * Placement


 * A fence gate can be placed on the top of most blocks. Once placed, the block beneath it may be removed without popping the fence gate.


 * Effect


 * While activated, a fence gate re-positions its two gates to either side, allowing movement through it. When activated, any entities on the fence gate will fall.


 * A fence gate doesn't actually "move" (the way a piston arm or a pushed block moves), it simply disappears from one state and re-appears in another, so it won't push entities as it "opens".


 * Unlike a door or trapdoor, while active, a fence gate is completely non-solid (lacks a collision mask) to all entities.

Hopper
A hopper is used to move items to and from containers (including other hoppers).


 * Placement


 * A hopper can be placed so that its output faces in any direction except up.


 * Effect


 * While not activated, a hopper pulls items from a container above it (or item entities in the space above it) into its own slots and pushes items from its own slots into a container it is facing (exception: a hopper will not push items into a chest or trapped chest that has a block on top of it which would prevent it from opening). Both types of transfers occur every 4 redstone ticks (0.4 seconds), and pulls are processed before pushes. A hopper always pulls items into the leftmost available slot, and pushes items from leftmost slots before rightmost slots (it won't start pushing items from the second slot before the first is empty, from the third slot before the second is empty, etc.).


 * While activated, a hopper does not pull items from above or push them out, but may receive items from other mechanism components and may have its items removed by another hopper beneath it.

Note block
A note block is used to produce a player-chosen sound.


 * Placement


 * After being placed, a note block's pitch can be adjusted over a two-octave range by right-clicking the note block, and its "instrument" can be adjusted by placing different blocks beneath it.


 * Effect


 * When activated, a note block produces a sound. A note block must have air above it to activate.


 * Considerations


 * A note block is an opaque block, so powering it directly can cause adjacent mechanism components (including other note blocks) to activate as well.

Piston
A piston is used to move blocks or entities. A piston may be of two types: a regular piston only pushes blocks, while a sticky piston pushes and pulls blocks.


 * Placement


 * A piston has a stone "pushing" component and a wooden "arm", and can be placed so the arm faces in any direction (its "front").


 * Activation


 * See Quasi-Connectivity above.


 * Effect


 * When activated, a piston pushes the block in front of its arm, and up to 11 more blocks in front of that (up to 12 blocks total). When deactivated, a regular piston pulls its arm back (leaving an air block in front of the piston), while a sticky piston pulls back both its arm and one block (leaving an air block on the other side of the pulled block).


 * A moving piston or block can also push an entity such as a mob or item.


 * Some blocks (bedrock, obsidian, chests, etc.) cannot be moved by a piston. Other blocks (flowers, leaves, torches, etc.) will be destroyed but may drop items (as if destroyed by the player). For full details of how pistons interact with other blocks, see Pushing Blocks.


 * Considerations


 * When a sticky piston is activated by a 1-tick pulse, it will push a block in front of it, but will fail to pull back the pushed block on the same pulse. If a sticky piston is activated by a 1-tick pulse when there is no block in front of it, it can pull back a block. Thus, a sticky piston running on 1-tick pulses will push and pull a block every other pulse.

Powered rail
A powered rail is used to propel a minecart.


 * Placement


 * A powered rail can be attached to the top of any opaque block, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the powered rail will "pop" off as an item.


 * When placed, a powered rail will configure itself to line up with adjacent rails, powered rails, and detector rails, as well as such adjacent rails one block up. If there are two such adjacent rails on non-opposite sides, or three or more such adjacent rails, a powered rail will line up in the east-west direction. If there are no such adjacent rails, a powered rail will line up in the north-south direction. If a rail it would line up with is one block up, a powered rail will slant upwards towards it (with multiple options to slant upwards to, a powered rail "prefers", in order: west, east, south, and north). Other configurations can be created by placing and removing various rail.


 * Activation


 * In addition to the methods above, a powered rail can also be activated by other adjacent activated powered rail. Powered rail can transmit activation up to 9 rails (the first originally-powered powered rail, and up to eight additional activated rails). Activation transmitted in this way cannot power any redstone components except powered rail.


 * Effect


 * While activated, a powered rail boosts the speed of a minecart passing over it, or starts a minecart moving away from an adjacent solid block it is in contact with.

Rail


A rail is used to switch the track of a minecart.


 * Placement


 * A rail can be attached to the top of any opaque block, or to the top of an upside-down slab or upside-down stairs. If the attachment block is removed, the rail will "pop" off as an item.


 * When placed, rail will configure itself to line up with adjacent rails, powered rails, and detector rails, as well as such adjacent rails one block up. If there are two such adjacent rails on non-opposite sides, the rail will curve from one to the other. If there are three or four such adjacent rails, the rail will curve between two of them (when choosing which directions to curve between, a rail "prefers" south over north, and east over west). If there are no such adjacent rails, the rail will line up in the north-south direction. If a rail it would line up with is one block up, a rail will slant upwards towards it without curving (with multiple options to slant upwards to, a rail "prefers", in order: west, east, south, and north). Other configurations can be created by placing and removing various rail.


 * Effect


 * While activated, a rail in a "T" junction flips to curve the other way (activating a rail in another configuration has no effect).

Redstone lamp
A redstone lamp is used to provide light.


 * Activation


 * A redstone lamp activates normally, but takes 2 ticks to deactivate.


 * Effect


 * While activated, a redstone lamp has block light level 15 (so produces block light level 14 in all adjacent transparent spaces). An activated redstone lamp is transparent to sky light.


 * Considerations


 * A redstone lamp is an opaque block, so powering it directly can cause adjacent mechanism components (including other redstone lamps) to activate as well.

TNT
TNT is used to create an explosion.


 * Activation


 * In addition to the methods above, TNT can also be activated by fire and explosions.


 * Effect


 * When activated, TNT ignites and becomes primed TNT, an entity which can fall like sand or be pushed by pistons (but isn't moved by water). Primed TNT explodes 40 ticks (4 seconds) after being ignited by redstone power (10-30 ticks for TNT ignited by an explosion).

Trapdoor
A trapdoor is used to control or prevent the movement of mobs, items, boats, and other entities.


 * Placement


 * A trapdoor can be attached to the top or the bottom of the side of most opaque blocks, as well as to glowstone, slabs, and stairs. If the attachment block is removed, the trapdoor will "pop" off as an item.


 * Slabs lack a full-side interaction mask – to attach a top trapdoor to a bottom slab, or a bottom trapdoor to a top slab, attach the trapdoor to another block and then use a piston to move the trapdoor into position with the slab, or move the slab into position with the trapdoor.


 * Effect


 * While activated, a trapdoor re-positions itself in a vertical state, allowing vertical movement through it. When activated, any entities on the trapdoor will fall.


 * A trapdoor doesn't actually "move" (the way a piston arm or a pushed block moves), it simply disappears from one state and re-appears in another, so it won't push entities as it "opens".

Boat
A boat is used to transport a player over water.


 * Behavior


 * While inside a boat, the player can move it with the movement control keys. A boat is also moved by flowing water, and will rise rapidly when submerged underwater.

Minecart
A minecart is used to transport a mob or player over rails.


 * Behavior


 * The player can move a minecart by pushing against it while outside the minecart (whether the minecart is on rails or not), or by pressing the Forward control key (by default, W) while inside the minecart (only while the minecart is on rails). A minecart resting on powered rails configured to point at an adjacent opaque block will be propelled away from the opaque block when the powered rails are activated. A minecart traveling over powered rails will have its speed boosted.

Minecart with chest
A minecart with chest (aka chest minecart, storage minecart) is used to store and transport items over rails.


 * Behavior


 * A minecart with chest will accept items from a hopper and will allow a hopper underneath it to pull items from it.

Minecart with command block
A minecart with command block (aka. command minecart, command block minecart) is used to execute commands.


 * Behavior


 * A minecart with command block will execute its command every 2 redstone ticks while on an activator rail.

Minecart with furnace
A minecart with furnace (aka furnace minecart, powered minecart) is used to push other minecarts over rails.


 * Behavior


 * A minecraft with furnace will propel itself and other minecarts without requiring powered rails.

Minecart with hopper
A minecart with hopper (aka hopper minecart) is used to collect, transport, and distribute items over rails.


 * Behavior


 * A minecart with hopper will pull items from containers above it and push items into hoppers below it (the number of items that will be transferred can depend on how long its velocity allows it to remain within reach of the containers). It will also pick up items that have fallen on the rails. If a minecart with hopper passes over a powered activator rail, it will stop transferring items indefinitely until it passes over an unpowered activator rail.

Minecart with TNT
A minecart with TNT (aka TNT minecart) is used to create explosions.


 * Behavior


 * A minecart with TNT which passes over a powered activator rail will explode( explosions from TNT minecarts will not damage rails or the blocks supporting rails).

Opaque blocks
Opaque blocks are blocks which block light and vision (with some exceptions: for example, glowstone is not considered an opaque block).

Opaque blocks are used to support redstone components and to transmit power.


 * Activation


 * An opaque block is strongly powered by an active power component, an active redstone repeater, or an active redstone comparator.


 * An opaque block is weakly powered by powered redstone dust on top of it, or configured to point at it.


 * Effect


 * A powered opaque block turns OFF any attached redstone torch, turns ON any adjacent redstone repeater or redstone comparator facing away from it, and activates any adjacent mechanism component.


 * A strongly-powered opaque block will turn ON any adjacent redstone dust, including redstone dust beneath or on top of the opaque block (but a weakly-powered opaque block will not).

Transparent blocks


Transparent blocks are blocks which either can be seen through fully (for example, glass) or partially (for example, stairs), or allow light to pass through (for example, leaves).

Transparent blocks can not transmit power, but are only needed as "insulators" in very compact circuits because air works just as well. Some transparent blocks have special properties that make them useful in redstone circuits:


 * Fences




 * A redstone torch or a pressure plate can be attached to the top of a fence or nether brick fence.


 * Glass




 * A redstone torch can be attached to the top of glass.


 * Glowstone




 * Redstone dust or a fence gate can be attached or placed on the top of glowstone, and a trapdoor can be attached to the side of glowstone. Redstone dust on top of glowstone can transmit power to redstone dust adjacent to it or diagonally upwards, but not diagonally downwards. Because glowstone is not opaque, it cannot power an adjacent block (including an attached trapdoor), but redstone dust on top of it can.


 * Slabs and Stairs




 * Any redstone component which can be attached or placed on an opaque block can also be attached or placed on an upside-down slab or upside-down stairs, and a trapdoor can be attached to the side of an upside-down slab or stairs (in single-player mode, a trapdoor cannot be placed on the "bottom" of an upside-down slab because there is no selection mask to interact with, but a slab moved to that position by a piston will not cause the trapdoor to pop).


 * Redstone dust on top of an upside-down slab or upside-down stairs can transmit power to a redstone dust adjacent to it or diagonally upwards, but not diagonally downwards. Because slabs and stairs are not opaque, they cannot be powered by power components and cannot provide power to adjacent blocks.


 * Walls




 * A redstone torch can be attached to the top of a cobblestone wall or mossy cobblestone wall.

红石元件