Redstone circuits

Redstone circuits are structures that can be built to activate or control mechanisms.

Circuits can be designed to act in response to player activation, or to operate autonomously -- either on a loop, or in response to non-player activity such as mob movement, item drops, plant growth, etc. The mechanisms that can be controlled by redstone circuits range from simple devices such as automatic doors and light switches, to complex devices such as elevators, automatic farms, or even in-game computers.

Understanding how to build and use redstone circuits and the mechanisms they can control will greatly increase the range of things that can be accomplished in Minecraft.

Basic concepts
Before describing the blocks used to build redstone circuits, or the types of circuits which can be built, an understanding of some basic concepts is required.


 * Redstone components
 * A redstone component is a block that provides some purpose to a redstone circuit.
 * A power component provides power to all or part of a circuit.
 * A transmission component passes power from one part of the circuit to another.
 * A mechanism component affects the environment (by moving, producing light, etc.).


 * Power
 * Some blocks may be powered or unpowered. Think of a "powered block" as a block that is electrified (but safe to touch). Some blocks will show their powered state visibly (for example, redstone wire lights up, a piston extends, etc.), but other blocks may give no visual indication of their powered state other than their effect on other redstone components.
 * Opaque blocks can be strongly-powered or weakly-powered (a different concept than power level, see below). The only difference is that a weakly-powered block will not power adjacent redstone wire.


 * Power level
 * Power level can vary from 0 to 15. Most power components provide power level 15, but a few provide a variable amount of power depending on how they are set up.
 * Redstone wire transmits power to adjacent redstone wire, but its strength decreases by 1 for each block traveled. Redstone wire can thus transmit power up to 15 blocks before needing to be re-strengthened (either with a redstone repeater, or by controlling a power source to create a new signal).


 * Redstone update
 * When a change occurs somewhere in a redstone circuit, it can produce other changes in surrounding blocks in what is called a redstone update (not to be confused with Minecraft 1.5, known as the 'Redstone Update'). Each of these changes can then produce other changes in their surrounding blocks. The update will propagate following the redstone circuit rules within loaded chunks. A common source of confusion comes when attempting to send redstone signals long distances, and finding that the signal stops when it hits an unloaded chunk or that conversely, a sensing signal from an unloaded chunk never arrives.


 * Redstone tick
 * A redstone tick is the moment when Minecraft updates redstone components. Redstone updates occur 10 times per second, so a redstone tick occurs every 0.1 seconds. Redstone torches, redstone repeaters, and mechanism components require one or more ticks to change state, so it can take a number of ticks for a signal to propagate through a complicated circuit.
 * Redstone ticks differ from "game ticks" (20 per second) and "block ticks" (block updates that occur at each game tick). When discussing redstone circuits, a "tick" is always a redstone tick, unless otherwise specified.


 * Signals and pulses
 * Circuits with a stable output are said to produce a signal -- an ON signal if powered, or an OFF signal if unpowered. When a signal changes from OFF to ON and then back again, that is described as a pulse (or ON pulse), while the opposite is described as an OFF pulse.
 * Very short pulses (1 or 2 ticks) can cause problems for some components or circuits because they may fail to keep up with the rapidly changing states.


 * Circuit vs. mechanism
 * These terms are sometimes used interchangeably to describe structures which incorporate redstone components, but a useful distinction can be made between the two:
 * A circuit performs operations on signals (generating, modifying, combining, etc.).
 * A mechanism manipulates the environment (moving blocks, opening doors, changing the light level, producing sound, etc.).
 * All mechanisms will necessarily incorporate redstone components or circuits, but a circuit by itself doesn't have to have an effect on the environment (except possibly incidentally, such as a redstone repeater changing its light level when changing its power state, or a piston moving a block to fulfill a role within the circuit). Making this distinction allows us to talk about circuits without having to define a specific in-game purpose for them, allowing players to find their own reasons to use them.
 * This article, and the other articles on redstone circuits, discuss only circuits which operate on signals. For articles about mechanisms, see the list of tutorials at the end of the article.


 * Size
 * A flat circuit (one which can generally be built along the ground's surface) is usually simply described by the area of its footprint (e.g., 3x4 for a circuit three block wide by four blocks long).
 * A circuit which incorporates significant height changes, or which fully utilizes all three dimensions by looping above itself, is described by the volume of the rectangular solid it occupies, usually with the height as the last value (for example, 3x4x5 for a circuit three block wide by four blocks long by five blocks high). Some members of the Minecraft community do not count the lowest layer of a circuit if it consists only of blocks required to support redstone components (for example, blocks underneath redstone wire) while others believe that any block necessary to the circuit should be counted in a circuit's size and blocks which do nothing but support redstone components are still necessary, in that removing them would break the circuit, and thus should be counted.

Redstone components
Redstone components are the blocks used to build a redstone circuit. Redstone components include power components (such as redstone torches, buttons, and pressure plates), transmission components (such as redstone wire and redstone repeaters), and mechanism components (such as pistons, doors, and redstone lamps). Many redstone components must be "attached" to other blocks and will "pop" (turn into items) if their support is removed.

Power components
Power components may be either attached or placed. An attached power components strongly-powers the block it occupies and one other adjacent block (see below), while placed power components only strongly-power their own block. Strongly-powered blocks can turn ON adjacent redstone wire, redstone repeaters, and powered mechanisms.

Attached power components

 * Button
 * A button may be of two types: wooden or stone.
 * Usage: A button is used to generate a pulse.
 * Placement: A button can be attached to the side of most opaque blocks.
 * 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 ON, a button powers the block it is in, and the block it is attached to.


 * Detector rail
 * Usage: 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 stair or upside-down slab.
 * 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 ON, a detector rail powers the block it is in, and the block beneath it (unless placed on an upside-down stair or slab).


 * Lever
 * Usage: 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 stair or upside-down slab.
 * Activation: A player can turn a lever ON or OFF by right-clicking it.
 * Effect: While ON, a lever powers the block it is in, and the block it is attached to (unless attached to an upside-down stair or slab).


 * Pressure plate
 * A pressure plate may be of two types: wooden or stone.
 * Usage: A pressure plate is used to detect mobs, items, and other entities.
 * 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 stair or upside-down slab.
 * 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 ON, a pressure plate powers the block it is in, and the block beneath it (unless placed on a fence, or an upside-down stair or slab).
 * 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
 * Usage: 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 glass, fence, nether brick fence, cobblestone wall, an upside-down stair or upside-down slab.
 * Activation: A redstone torch stays ON until the block it is attached to is powered.
 * Effect: While ON, a redstone torch powers the block it is in and any opaque block above it (but not the block it is attached to).
 * 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 wire 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 wire, 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 wire, don't attach the torch to the block supporting the wire or you'll get burn-out.


 * Tripwire hook
 * Usage: 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.
 * 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. A tripwire circuit is placed correctly when the tripwire hook is fully extended and the tripwire 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 the entity leaves or is 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, also does not generate a pulse).
 * Effect: While ON, a tripwire hook powers the block it is in, and the block it is attached to. Tripwire provides no power itself.
 * Considerations: To place tripwire, right-click on an adjacent block with a string. Tripwire does not need to be supported when placed (it can be placed "floating" in the air), but if an opaque block (or upside-down slab or stair) directly underneath it is placed or removed, the tripwire will "pop" (turn back into string).


 * Weighted pressure plate
 * A weighted pressure plate may be of two types: light (gold) or heavy (iron).
 * Usage: A weighted pressure plate is used to measure the number of items on top of it.
 * 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 stair or upside-down slab.
 * Activation: A weighted pressure plate is turned ON by one or more items on top of it.
 * Effect: While ON, a weighted pressure plate strongly-powers the block it is in, and the block beneath it (unless placed on a fence, or an upside-down slab or stair), at a power level proportionate to the number of items on top of it: items/4 for a light weighted pressure plate (round up; i.e., power level 1 for 1-4 items, power level 2 for 5-8 items, etc.), or 3*items/128 for a heavy weighted pressure plate (round up; i.e., power level 1 for 1-42 items, power level 2 for 43-85 items, etc.).

Placed power components

 * Block of redstone
 * Usage: 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 turns ON adjacent redstone wire, redstone repeaters and redstone comparators facing away from it, and mechanism components. A block of redstone has no effect on adjacent opaque blocks.


 * Daylight sensor
 * Usage: A daylight sensor is used to measure the "height" of the sun.
 * Activation: A daylight sensor turns ON at dawn and turns OFF at night.
 * Effect: While ON, a daylight sensor strongly-powers the block it is in, at a power level proportionate to the height of the sun in the sky.


 * Trapped chest
 * Usage: 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 ON, a trapped chest strongly-powers the block it is in, at a power level equal to the number of players accessing its contents.

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
 * Usage: 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 stair or upside-down slab.
 * 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 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 wire, 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 wire, 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 minecart (a non-stackable item), 16 snowballs, or 64 cobblestone are all considered to be full stacks and count equally towards a container's fullness.


 * {| class="collapsed collapsible wikitable" style="text-align:center;"

! colspan=17 | Container power level !Container!!Slots!! 1 !!2!!3!!4!!5!!6!!7!!8!!9!!10!!11!!12!!13!!14!!15
 * colspan=17 | Power level requires: stacks+items (64-stackable/16-stackable)
 * colspan=17 | Power level requires: stacks+items (64-stackable/16-stackable)
 * Chest (single)||27||1i||1s+60/15i||3s+55/14i||5s+51/13i||7s+46/12i||9s+42/11i||11s+37/10i||13s+32/8i||15s+28/7i||17s+23/6i||19s+19/5i||21s+14/4i||23s+10/3i||25s+5/2i||27s
 * Chest (double)||54||1i||3s+55/14i||7s+46/12i||11s+37/10i||15s+28/7i||19s+19/5i||23s+10/3i||27s||30s+55/14i||34s+46/12i||38s+37/10i||42s+28/7i||46s+19/5i||50s+10/3i||54s
 * Dispenser/Dropper||9||1i||42/11i||1s+19/5i||1s+60/15i||2s+37/10i||3s+14/4i||3s+55/14i||4s+32/8i||5s+10/3i||5s+51/13i||6s+28/7i||7s+5/2i||7s+46/12i||8s+23/6i||9s
 * Furnace||3||1i||14/4i||28/7i||42/11i||55/14i||1s+5/2i||1s+19/5i||1s+32/8i||1s+46/12i||1s+60/15i||2s+10/3i||2s+23/6i||2s+37/10i||2s+51/13i||3s
 * Hopper||5||1i||23/6i||46/12i||1s+5/2i||1s+28/7i||1s+51/13i||2s+10/3i||2s+32/8i||2s+55/14i||3s+14/4i||3s+37/10i||3s+60/15i||4s+19/5i||4s+42/11i||5s
 * }
 * Furnace||3||1i||14/4i||28/7i||42/11i||55/14i||1s+5/2i||1s+19/5i||1s+32/8i||1s+46/12i||1s+60/15i||2s+10/3i||2s+23/6i||2s+37/10i||2s+51/13i||3s
 * Hopper||5||1i||23/6i||46/12i||1s+5/2i||1s+28/7i||1s+51/13i||2s+10/3i||2s+32/8i||2s+55/14i||3s+14/4i||3s+37/10i||3s+60/15i||4s+19/5i||4s+42/11i||5s
 * }
 * Hopper||5||1i||23/6i||46/12i||1s+5/2i||1s+28/7i||1s+51/13i||2s+10/3i||2s+32/8i||2s+55/14i||3s+14/4i||3s+37/10i||3s+60/15i||4s+19/5i||4s+42/11i||5s
 * }


 * Redstone repeater
 * Usage: A redstone repeater is used to transmit power, re-strengthen redstone wire 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 stair or upside-down slab.
 * 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 wire 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. A locked repeater will not change its output state until unlocked, even if its input changes.


 * Redstone wire
 * Usage: Redstone wire is used to transmit power.
 * Placement: Redstone wire is placed by right-clicking with redstone (dust is the item, wire is the block). Redstone wire can be attached to the top of any opaque block, or to the top of glowstone, an upside-down stair or upside-down slab.
 * When placed, redstone wire will configure itself to point towards adjacent redstone wire (at the same level or one level up or down), correctly-facing redstone repeaters, and power components. If there is only one such neighbor, redstone wire 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 wire fill form either a line, an "L", a "T", or a "+". If there are no such neighbors, redstone wire will form a large directionless dot. Redstone wire won't automatically configure itself to point towards adjacent mechanism components, it must be arranged to do so.
 * When two redstone wires are placed vertically diagonally (one block over and one up, or one over and one down), the lower wire will appear to "crawl" up the side of the higher block to join the other wire. This linking can be "cut" by an opaque block above the lower wire, which prevents the two wires from connecting visually or transmitting power to each other. If the higher wire is on an upside-down stair or upside-down slab, the higher wire will configure itself to point towards the lower wire (and other adjacent wire), but the lower wire will not configure itself to point towards the higher wire (including not appearing to "crawl" up the side of the slab or stair).
 * The directions in which redstone wire configures itself can affect whether it powers adjacent opaque blocks and mechanisms.
 * Activation: Redstone wire can be turned ON by any adjacent power component, redstone repeater pointing at it, or strongly-powered opaque block. Redstone wire can also be turned ON by other adjacent powered redstone wire, but the power decreases with distance from a strongly-powered block. Redstone wire can transmit power up to 15 blocks.
 * Redstone wire can transmit power diagonally upwards to wire on an upside-down stair or upside-down slab, but not diagonally downwards from an upside-down stair or upside-down slab.
 * Effect: Powered redstone wire 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).
 * Note: The in-game name for redstone placed as a block is "redstone dust", but for technical reasons the wiki is still using the old name "redstone wire".


 * Opaque blocks
 * Usage: Opaque blocks are used to support redstone components and to transmit power.
 * Activation: An opaque block is strongly powered by an active power component or an active redstone repeater, or weakly powered by active redstone wire above it or configured to point at it.
 * Effect: A powered opaque block turns OFF an attached redstone torch, turns ON an adjacent redstone repeater facing away from it, and turns ON an adjacent mechanism component. A strongly-powered opaque block will turn ON adjacent redstone wire, including redstone wire beneath the opaque block (but a weakly-powered opaque block will not).
 * Considerations: To attach redstone components to blocks you interact with by right-clicking (e.g., crafting table, furnace, dispenser, note block, and a jukebox containing a record), sneak while right-clicking.


 * Transparent blocks
 * 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:
 * Glowstone: A redstone wire or fence gate can be attached or placed on the top of glowstone, and a trapdoor can be attached to the side of glowstone. A redstone wire on top of glowstone can transmit power to a redstone wire 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 wire on top of it can.
 * Slabs and stairs: A redstone torch, redstone wire, redstone repeater, lever, pressure plate (wooden or stone), rail (regular, powered, or detector), door (wooden or iron), and a fence gate can all be attached or placed on the top of an upside-down slab or upside-down stair, and a trapdoor can be attached to the side of an upside-down slab or stair (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). A redstone wire on top of an upside-down slab or upside-down stair can transmit power to a redstone wire 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.
 * Glass and fences: A redstone torch can be attached to the top of glass, and a redstone torch or a pressure plate can be attached to the top of a fence or nether brick fence.

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 (Exception: a redstone torch will not turn ON a mechanism component it is attached to)
 * an adjacent powered opaque block (strongly-powered or weakly-powered)
 * a powered redstone repeater facing the mechanism component
 * powered redstone wire 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 wire which is not configured to point at it.


 * Activator rail
 * Usage: 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 stair or upside-down slab.
 * 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 turned ON by other adjacent active activator rail, but the power decreases with distance from a power component. Activator rail can transmit power up to 9 rails (the first originally-powered powered rail, and up to eight additional powered rails). Power transmitted in this way cannot power any redstone components except activator rail.
 * Effect: An activator rail affects certain minecart passing over it. The effects vary with the type of minecart powered:
 * A minecart with TNT will be ignited by a powered activator rail.
 * A minecart with hopper will be turned OFF by a powered activator rail (it will stop sucking up items in its path, or transferring items to containers as it passes them), and turned ON by an unpowered activator rail.
 * Other minecarts are not affected by an activator rail.


 * Command block
 * Command blocks can only be obtained with the command.
 * Usage: A command block is used to execute a server command.
 * Placement: After being placed, the player can set the command to be executed by right-clicking on the command block.
 * Effect: When turned ON, a command block executes a specific player-defined command once.


 * Dispenser
 * Usage: A dispenser is used to interact with the environment with items.
 * Activation: In addition to the methods above, a dispenser can also be turned ON if one of the methods above would activate a mechanism component in the block above the dispenser, even if there is no mechanism component there (even if the block above the dispenser is air or a transparent block), but only when the dispenser receives a block update (including a redstone update within two blocks of the dispenser). This is known as piston connectivity (see Piston below).
 * Effect: When turned ON, a dispenser will trigger. The effects of being triggered vary with the items in the dispenser:
 * {| class="wikitable collapsible collapsed"

! 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 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
 * 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
 * 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
 * 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
 * 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
 * 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
 * Ignites the block the dispenser is facing; reduces the remaining durability of the used flint and steel
 * 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 )
 * }
 * If the dispenser is facing a container, the ejected item will simply be transferred into the container.
 * Considerations: A dispenser is an opaque block, so powering it directly can cause adjacent mechanism components (including other dispensers) to activate as well.
 * }
 * If the dispenser is facing a container, the ejected item will simply be transferred into the container.
 * 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 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.
 * Usage: A door is used to control or prevent the movement of mobs, items, boats, and other entities.
 * 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 stair.
 * 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 ON, 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 it turns ON, 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
 * Usage: A dropper is used to eject items or push them into containers (including other droppers).
 * Activation: In addition to the methods above, a dropper can also be turned ON if one of the methods above would activate a mechanism component in the block above the dropper, even if there is no mechanism component there (even if the block above the dropper is air or a transparent block), but only when the dropper receives a block update (including a redstone update within two blocks of the dropper). This is known as piston connectivity (see Piston below).
 * Placement: A dropper can be placed so that its output faces in any direction.
 * Effect: When turned ON, a dropper ejects a random item in the direction the dropper is facing, as if the player had used the Drop control. If the dropper is facing a container, the ejected item will be transferred into the container.
 * 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
 * Usage: 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 ON, a fence gate re-positions its two gates to either side, allowing movement through it. When it turns ON, 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 ON, a fence gate is completely non-solid (lacks a collision mask) to all entities.


 * Hopper
 * Usage: 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 OFF, a hopper transfers items from a container above it into its own slots and transfers items from its own slots into a container it is facing. Both types of transfers occur every 3.5 redstone ticks. While ON, a hopper does not pull items from above or push them out, but may receive items from other mechanism components.


 * Note block
 * Usage: 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 it's "instrument" can be adjusted by placing different blocks beneath it.
 * Effect: When turned ON, 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 may be of two types: a regular piston only pushes blocks, while a sticky piston pushes and pulls blocks.
 * Usage: A piston is used to move blocks or entities. May be part of a circuit's output (such as a circuit built to control a piston door), or may be incorporated within the circuit to change a circuit's configuration (for example, by moving an opaque block over a redstone torch or away from it).
 * 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 by piston connectivity.pngActivation: In addition to the methods above, a piston can also be turned ON if one of the methods above would activate a mechanism component in the block above the piston, even if there is no mechanism component there (even if the block above the piston is air or a transparent block), but only when the piston receives a block update. This is known as piston connectivity (the piston is "connected" to the block above for the purposes of activation).
 * Effect: When turned ON, a piston pushes the block in front of its arm, and up to 11 more in front of that (up to 12 blocks total). When turned off, 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
 * Usage: 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 stair or upside-down slab.
 * 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 turned ON by other adjacent active powered rail, but the power decreases with distance from a power component. Powered rail can transmit power up to 9 rails (the first originally-powered powered rail, and up to eight additional powered rails). Power transmitted in this way cannot power any redstone components except powered rail.
 * Effect: While ON, 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
 * Usage: 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 stair or upside-down slab.
 * 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 ON, a rail in a "T" junction flips to curve the other way (powering a rail in another configuration has no effect).


 * Redstone lamp
 * Usage: A redstone lamp is used to provide light.
 * Effect: While ON, a redstone lamp produces block light level 15.
 * 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
 * Usage: 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 turned ON, 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
 * Usage: 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.
 * 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 ON, a trapdoor re-positions itself in a vertical state, allowing vertical movement through it. When it turns ON, 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".

Containers
Containers are used in redstone mechanisms to hold, move, or process items.


 * {| class="wikitable collapsible collapsed"

! colspan="3" | Container Properties ! Container ! Slots ! Notes
 * style="text-align: center;" | 4
 * Brews potions.
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * style="text-align: center;" | 9
 * style="text-align: center;" | 9
 * style="text-align: center;" | 27
 * A redstone comparator will not output a signal from an ender chest. A hopper or a minecart with hopper will not move items into or out of an ender chest.
 * style="text-align: center;" | 3
 * Smelts items. A redstone comparator's output from a furnace reflects the total fullness of all three slots (fuel, input, and output).
 * style="text-align: center;" | 5
 * style="text-align: center;" | 1 (special)
 * A jukebox can only contain a single record. A redstone comparator's output from a jukebox reflects which record is in the jukebox.
 * style="text-align: center;" | 27
 * style="text-align: center;" | 5
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * }
 * style="text-align: center;" | 27
 * A redstone comparator will not output a signal from an ender chest. A hopper or a minecart with hopper will not move items into or out of an ender chest.
 * style="text-align: center;" | 3
 * Smelts items. A redstone comparator's output from a furnace reflects the total fullness of all three slots (fuel, input, and output).
 * style="text-align: center;" | 5
 * style="text-align: center;" | 1 (special)
 * A jukebox can only contain a single record. A redstone comparator's output from a jukebox reflects which record is in the jukebox.
 * style="text-align: center;" | 27
 * style="text-align: center;" | 5
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * }
 * style="text-align: center;" | 1 (special)
 * A jukebox can only contain a single record. A redstone comparator's output from a jukebox reflects which record is in the jukebox.
 * style="text-align: center;" | 27
 * style="text-align: center;" | 5
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * }
 * style="text-align: center;" | 27
 * style="text-align: center;" | 5
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * }
 * style="text-align: center;" | 5
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * }
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * }
 * style="text-align: center;" | 27 (Single) or 54 (Double)
 * }
 * }

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.

Mobile components

 * Boat
 * Usage: 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
 * Usage: 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
 * Usage: A minecart with chest (a.k.a. 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 furnace
 * Usage: A minecart with furnace (a.k.a. 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
 * Usage: A minecart with hopper (a.k.a. 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
 * Usage: A minecart with TNT (a.k.a. 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).

Circuit designs
Although the number of ways to construct circuits is endless, certain patterns of construction occur over and over again. The following sections attempt to categorize the circuits which have proven useful to the Minecraft community, while the main articles describe the specific circuits which fall into those categories.

Some of these circuits might be used by themselves for simple control of mechanisms, but frequently you will need to combine them into more complex circuits to meet the needs of a mechanism.

Transmission circuits
Some aspects of signal transmission can be helpful to understand: vertical transmission, repeaters, and diodes.


 * Vertical transmission
 * Although horizontal signal transmission is pretty straight-forward, vertical transmission involves options and trade-offs.
 * Wire staircases: The simplest way to transmit signals vertically is by placing redstone wire on blocks diagonally upwards, either in a straight staircase of blocks, in a 2×2 spiral of blocks, or in another similar variation. Wire staircases can transmit signals both upwards and downwards, but can take up a lot of space and will require repeaters every 15 blocks.
 * Wire ladders: Because glowstone, upside-down slabs and upside-down stairs can support redstone wire but don't cut redstone wire, signals can be transmitted vertically (upwards only) by alternating these blocks in a 2×1 "ladder". Wire ladders take up less space than wire staircases, but also require repeaters every 15 blocks.
 * Torch towers: A redstone torch can power a block above it, or redstone wire beneath it, allowing vertical transmission both upwards or downwards (different designs are required for each). Because it takes each torch a little time to change state, a torch tower can introduce some delay into a circuit, but no repeaters are necessary.
 * Other forms of vertical transmission are possible, using pistons, water, etc.


 * Repeaters
 * To "repeat" a signal means to boost it back up to full strength. The easiest way to do this is with a redstone repeater, but some circuits may require circuits known as "instant repeaters" that repeat a signal without the delay introduced by a redstone repeater.


 * Diode
 * A "diode" is a one-way circuit that allows a signal to travel only in one direction. It is used to protect another circuit from the chance of a signal trying to enter through the output, which could incorrectly change the circuit's state or interfere with its timing. It is also used in a compact circuit to keep one part of the circuit from interfering with another. Common choices for a diode include a redstone repeater or a height elevation to glowstone or an upside-down slab which won't transmit a signal back downwards.
 * Many circuits are already one-way simply because their output comes from a block which can't take input. For example, you can't push a signal back into a circuit through a redstone torch except through the block it's attached to.

Logic circuits
It's sometimes necessary to check signals against each other and only output a signal when the inputs meet some criteria. A circuit which performs this function is known as a logic gate (a "gate" that only allows signals through if the "logic" is satisfied). Although there are many different possible "logics" that could be checked, the two most common ones are the OR Gate and the AND Gate (possibly with inputs or outputs inverted).


 * OR gate
 * An OR Gate produces an ON output if any of its inputs is ON (i.e., its output is ON if input A is ON or input B is ON, or input C is ON, etc.).


 * AND gate
 * An AND Gate produces an ON output only if all of its inputs are ON (i.e., its output is ON if input A is ON and input B is ON and input C is ON, etc.).

Inverting a signal (such as with a redstone torch) is also considered a logical operation (a NOT gate, because the output is always NOT the same as the input).

Pulse circuits
Some circuits require specific pulses, other circuits use pulse duration as a way to convey information. Pulse circuits manage these requirements.

A circuit which is stable in one output state and unstable in the other is known as a monostable circuit. Many pulse circuits are monostable because their OFF state is stable, but their ON state will quickly revert back to OFF.


 * Pulse generator
 * A pulse generator produces a pulse of a specific duration.


 * Pulse limiter
 * A pulse limiter (a.k.a. pulse shortener) reduces the duration of pulses which are too long.


 * Pulse extender
 * A pulse extender (a.k.a. pulse sustainer, pulse lengthener) increases the duration of pulses which are too short.


 * Pulse delay
 * A pulse delay circuit delays a pulse by a specific duration.


 * Edge detector
 * An edge detector reacts to either a signal changing from OFF to ON (a "rising edge" detector) or from ON to OFF (a "falling edge" detector), or both (a "dual edge" detector).


 * Pulse duration tester
 * A pulse duration tester reacts only to pulses in a certain range of durations (often only to pulses of one specific duration).


 * Pulse counter
 * A pulse counter records the number of pulses sent through a circuit.


 * Oscilloscope
 * An oscilloscope is a sequence of redstone repeaters all set to a 1-tick delay. By seeing how many repeaters light up, you can observe the duration of a pulse. By running multiple oscilloscopes in parallel, you can compare the duration and delay of pulses produced by different circuits.

Clock circuits
A clock circuit is a pulse generator that produces a loop of specific pulses over and over again. Some are designed to run forever, while others can be stopped and started.

A simple clock with only two states of equal duration is named for the duration of its ON state (e.g., for example, a clock which alternates between a 5-tick ON state and a 5-tick OFF state is called a 5-clock) while others are usually named for their period (the time it takes for the clock to return to its original state; for example, a "1-minute clock" might produce a 1-tick pulse every 60 seconds).


 * Repeater clocks
 * A repeater clock consists of a loop of repeaters (usually either redstone repeaters or redstone torches) with occasional wire or blocks to draw off the appropriate pulses.


 * Hopper clocks
 * A hopper clock produces timed pulses by moving items around between hoppers and drawing signals off with redstone comparators.


 * Piston clocks
 * A piston clock produces a loop of pulses by passing a block back and forth (or around, with many pistons) and drawing off a pulse when the block is in a certain location.

Clocks can also be built based on minecarts, boats, item despawn, etc.

Memory circuits
Unlike a logic circuit whose state always reflects its current inputs, a memory circuit's output depends not on the current state of its inputs, but on the history of its inputs. This allows a memory circuit to "remember" what state it should be in, until told to remember something else.


 * T flip-flop
 * A T Flip-Flop is used to toggle a signal (like a lever). It has a primary input and a "clock" input, and its output changes state ("toggles") only when both the primary input and the clock input are ON at the same time. In practical redstone circuits, the clock input is often omitted from the circuit so that the output toggles whenever the primary input turns ON (turning it into a T Latch).


 * SR latch
 * An SR Latch is used when you need greater control of the circuit's output state. It has two separate inputs, a SET input and a RESET input. Its output is set to ON when SET turns ON, and remains ON until RESET turns ON (no matter what SET does). When the output is OFF, it remains OFF until SET turns ON.
 * An SR latch built from NOR gates is known as an "RS NOR Latch".

Many other memory circuits are possible.

Block update detectors
A block update detector (BUD, or BUD Switch) is a circuit which "reacts" to a block changing its state (for example, stone being mined, water changing to ice, a pumpkin growing next to a pumpkin stem, etc.). BUDs react by producing a pulse, while T-BUDs (Toggleable BUDs) react by toggling their output state.


 * Piston-connectivity BUDs
 * Circuits that put a piston into a meta-stable state by powering the piston by piston-connectivity without providing a block update to inform it that it is powered, causing the piston to finally react when a block updates next to it.


 * Stuck-piston BUDs
 * Circuits which put a piston into a meta-stable state by powering it when it is unable to extend (such as when another extended piston is blocking it), then removing the obstacle in a way that doesn't cause the powered piston to update, causing it to finally react when a block updates next to it.

Other block update detectors are possible, using boats, minecarts, redstone lamps, etc.

Miscellaneous circuits
These circuits aren't generally needed for your typical project, but might find use in complex projects, proofs of concept, and thought experiments. Some examples:


 * Multiplexers
 * A multiplexer is an advanced form of logic gate which chooses which input to let through as output based on an additional input (for example, if input A is ON then output input B, otherwise output input C).


 * Randomizers
 * A randomizer produces output signals unpredictably. Randomizers can be designed to produce a pulse at random intervals, or to randomize which of multiple outputs are turned ON (such as random number generators, or RNGs). Some randomizers use the random nature of Minecraft (such as cactus growth or dispenser slot selection), while others produce pseudo-randomness algorithmically.


 * Multi-bit circuits
 * Multi-bit circuits treat their input lines as a single multi-bit value (something other than zero and one) and perform an operation on them all at once. With such circuits, possibly combined with arrays of memory circuits, it's possible to build calculators, digital clocks, and even basic computers inside Minecraft.

Many more complex circuits are possible.

Planning
The first step in building a redstone circuit is to decide what it will do.


 * How and where will it be controlled?
 * Will the circuit be controlled by the player, by mob movement, or something else?
 * What mechanism components will it control?
 * How will the signal be transmitted from the controls to the mechanisms?
 * Will signals need to be combined from multiple sources?

Construction
It can be helpful to choose a specific set of blocks you use to construct circuits. Then, when you run into these blocks when digging out new rooms in your base, you know you're about to damage a previously-built circuit. Common choices include stone brick, snow block, and wool. (Using different colors of wool is also a great way to keep track of different circuits)

Be careful when building circuits near water or lava. Many redstone components will "pop" (turn into items) when washed over by liquids, and lava will destroy any items it contacts.

Be careful when building circuits to activate TNT (traps, cannons, etc.). Circuits in mid-construction can sometimes briefly power up unexpectedly, which might activate TNT. For example, if you place a redstone torch on a powered block, it won't "figure out" that it should be turned off until the next tick, and can briefly power another part of the circuit until then. Placing your TNT after the rest of the circuit is complete will help to avoid such problems and the destruction of the device itself.

Problem-solving
When your circuit isn't working the way you think it should, take a look at it and try to find the problem.


 * Are you trying to draw power from a weakly-powered block? Maybe you need a redstone repeater to strongly-power the block, or to pull power out of the block.
 * Are you trying to transmit power through a non-opaque block? Replace it with an opaque block, or go around it.
 * Did you create a short-circuit and a redstone torch that should be powered is now burned out? Fix the short-circuit and update the torch to get things going again.
 * Are parts of your circuit activating when they shouldn't be? Maybe you've accidentally "crossed wires" allowing a signal from one part of the circuit to activate another part of the circuit.
 * Did the behavior you were using get removed?
 * Are pistons or dispensers being indirectly powered?

Refining
Once your circuit is working, consider if it can be improved (without breaking it).


 * Can you make the circuit faster?
 * Reducing the number of components a signal has to travel through can speed up the circuit.
 * Can you make the circuit smaller?
 * Can you use fewer blocks?
 * Can you shorten the redstone wire lines?
 * Can you make the circuit more robust?
 * Will the circuit still work when activated by a very short pulse?
 * Will the circuit still work when activated and deactivated rapidly in succession?
 * Did an update create the opportunity for a better circuit? (e.g. pistons, locking repeaters, etc.)