On Java Edition, try the interactive map designed to accompany the tutorials.
Pistons are a key ingredient for sugarcane farming.
Redstone mechanisms are blocks that affect the environment (with light, sound, movement, etc.) when activated. They are the parts of redstone devices that actually do things!
In the last few chapters, you learned ways of transmitting power where you want. Now you'll learn how to use that power to do more things with various redstone mechanisms.
We'll cover the basics of each mechanism one by one. More advanced applications will be covered later.
What is an entity?
First, some redstone mechanisms affect what are called entities, so let's take a moment to get clear on what that means.
There are essentially two types of objects you can interact with in the Minecraft world: blocks and entities. Entities include players, mobs, and items waiting to be picked up.
Examples of entities. Note the dirt block on the right, which is in entity form rather than a placed block.
Blocks generally stay in place until broken, but entities are affected by physics. They fall if in the air, can get submerged in (and moved by) water, knocked around by explosions, etc.
Zombie held in place by opposing water currents
Now, on to the redstone mechanisms!
Redstone Lamps
You're already familiar with these from previous chapters. They're very straightforward: when powered, they generate light of level 15 (the brightest possible). When unpowered, they give off no light.
Redstone lamps give off light level 15 when powered.
Doors, Trapdoors, and Fence Gates
These mechanisms are only slightly more complicated than lamps. Rather than being open whenever they are powered, they open (if they are not already) when transitioning from unpowered to powered, and they close (if they are not already closed) when transitioning from powered to unpowered.
A powered, (manually) closed door
This means that, for example, you can't force a door to stay open by supplying power to it. A player can manually close it, and it will stay closed. (Except for iron doors, which cannot be operated manually.)
Regular doors, which are two blocks tall, respond to redstone power routed into either their top or bottom block.
Two ways of powering a door
Pressure plates are a natural pairing for doors, since they'll open the door when you step on, and close the door a moment after you step off. But be careful -- mobs can trigger them too, so be cautious about putting them outside the main door of your base!
Pressure plate placed to power a door
Bells
Bells are found at the center of villages, and serve as a gathering place for villagers on their normal schedule. They serve as a village alarm -- when rung, villagers scurry to the safety of their homes.
You can ring bells by hand, but they'll also ring once (and only once) when powered.
Villager standing next to a bell
TNT
Powering a TNT block lights its fuse so that it explodes about 4 seconds later. Just like if you light it manually using flint and tinder.
When a TNT block is activated (that is, when its fuse is lit), it changes from a block to an entity.
This is important, because being an entity means it can be submerged in water. If lit TNT is submerged in water when it detonates, it will not affect blocks -- only other entities.
This fact can be leveraged to build redstone cannons, which use TNT to propel entities (including other lit TNT!) without destroying the device itself.
A simple player cannon that can launch players into the air. The player stands on the tip of the arrow and presses the button. (Blast Protection armor required!)
Note Blocks
Note blocks can be used to make music!
A note block plays one musical note when powered, or when you briefly Attack it (left-click, if you are using a mouse). The length of the note is always the same.
By default, note blocks play an FāÆ. They can be tuned by using them with your character; each use of the note block will set it to play the next higher note (for example, G instead of FāÆ). Note blocks cover a two octave range, with an F# as both the lowest and highest note.
Visual indicator of a note block playing a musical note
Note blocks require the block above them to be empty in order to make sound.
This note block won't work.
Note blocks also play different instruments depending on what type of block is underneath them! There are a total of 16 different instruments, each with a different 2-octave pitch range (all starting and ending at F#).
The Official Minecraft Wiki lists what types of blocks activate which instruments.
The block under a note block determines the instrument played.
Note blocks can be heard up to 48 blocks away, which is actually quite far. (Those cows in your farm, for example, can only be heard 16 blocks away.)
Repeaters introduce a slight delay before they transmit power, and the length of this delay can be configured by right-clicking on the repeater. We'll explore this in more detail in a later chapter, but for now, you can use this to create simple tunes!
Rails
Rails are great for all sorts of things, like transportation networks, moving items around, or rollercoasters!
Rail mechanisms
Powered Rails
Minecarts don't move themselves, and even if you push them they quickly lose momentum. You need powered rails to accelerate them (by which we mean the block called "powered rail", not "a regular rail that is receiving redstone power").
Powered rails routed into OCBs accelerate minecarts away when activated.
If a powered rail runs directly into an OCB (opaque cubic block ā see Chapter 3), then when it is activated, it will accelerate minecarts away from the OCB.
Powered rails in the middle of a track will accelerate minecarts in the direction they're already moving if activated, but they won't accelerate a minecart that's standing still.
If not activated, powered rails will actually stop a moving minecart.
Multiple powered rails in a row accelerate a minecart more (up to a maximum velocity of 8 blocks per second). When a powered rail receives redstone power, it not only activates that particular powered rail, but up to eight contiguous powered rails on either side of it!
One central powered rail activating 16 additional powered rails
Unlike regular rails, powered rails don't curve.
See? I told you.
(Regular) Rails
When a rail sits at the junction of a T intersection, powering the rail will make it curve in the other direction. This can be used to create switchable rail networks.
This rail will curve the other direction if powered.
Activator rails
Some redstone mechanisms (TNT, hoppers, and command blocks) are available as minecart variants (you can craft a "minecart with TNT" a unique item that is neither minecart nor TNT). Activator rails, when powered, will activate these mechanisms (igniting the TNT fuse, for example).
In Java Edition, TNT minecarts activated by activator rails won't damage rails.
The aftermath of a TNT minecart passing an activated activator rail in Java Edition.
Like powered rails, a powered activator rail also activates up to 8 contiguous activator rails on either side.
Pistons and Sticky Pistons
Pistons (whether regular or sticky), when activated, push both blocks and entities.
Activated piston
In some cases, they break blocks. They'll break a sugarcane block, for example, which is useful in building automated sugarcane farms.
There are some restrictions on what blocks they affect. For example, pistons can't move obsidian. In Java Edition, pistons can't move hoppers or dispensers.
The Official Minecraft Wiki has a full chart detailing the restrictions.
Piston breaking sugarcane
When sticky pistons retract, they also pull the block in front of them back with them. This can be used to build things like secret doors.
A lever-activated secret door constructed with sticky pistons. Some stone replaced with glass for illustrative purposes.
Pistons can push (but not pull) multiple blocks at once -- up to a max of 12.
Piston moving 12 blocks
You can't activate a piston by powering it from the front.
This wonāt work.
In Java Edition, you also can't attach certain blocks like levers or ladders directly on a piston ā they'll just break as soon as the piston moves.
In Java Edition, this wonāt work either.
Also in Java Edition only: Pistons are also subject to an advanced form of power transmission called quasi-connectivity. Quasi-connectivity can sometimes cause a piston to activate when power is transmitted to the block above it, even if that block only contains air.
Quasi-connectivity is complex and will be covered in a future chapter. For now, just be aware it exists, and if your pistons are activating when you don't expect them, try relocating power sources and charged blocks a block or two further away.
Java Editionās terribly confusing world of quasi-connectivity
Hoppers
Hoppers are a tool used to move items from one place to another.
They are containers, meaning they have inventory slots you can open and put and take things from, just like a chest. Usually you won't use a hopper this way, except during testing & troubleshooting. But it's important to understand how they work.
Because hoppers are containers, you need to hold Sneak (if you're using a keyboard, the default binding is Shift) when placing a block while your cursor is on a hopper -- otherwise you'll just open the hopper's inventory.
Examples of containers. Note that things like furnaces are containers, too.
Hopper deactivated by redstone power
Unlike most redstone mechanisms, hoppers are activated when unpowered, and deactivated when powered. This makes simple hopper devices very easy to build (no redstone power required!).
It can also cause confusing bugs sometimes -- if one of your hoppers mysteriously stops moving items, it might be because you're accidentally powering it.
Hoppers do two things:
They pull items from the block above them into their inventory
They push items from their inventory into the container their output is attached to
Hoppers will pull items from a container (possibly another hopper!) in the block above them. We'll call this a source container.
Hopper placed to pull items from a chest
They will also pull item entities within one block of space above them.
Normally this means anything sitting directly on top of the hopper, but if there's a block above the hopper which doesn't fill the entire block of space (like a bottom half slab, or carpet), this includes item entities sitting on top of that block!
These hoppers will pull item entities sitting directly on top of them (left), or on top of the slab (right)
Hopper output can be pointed down or to any side (but not up, since that's where the hopper pulls from). The direction of output is determined at the time the hopper is placed -- it will point towards whatever block you clicked on when placing the hopper. (Since this will usually be a container, you'll need to hold Sneak to place the hopper.)
Hopper outputs pointing in different directions
Hoppers typically move items at a rate of 2.5 items per second. They do this until there's no more space to do so (their inventory has no space to pull new items into, or the target container's inventory has no space to push items into).
For containers with multiple inventories, which inventory the hopper interacts with depends on which side of the container it's attached to. With furnaces, for example:
Hoppers attached to the top push into the furnace's inventory for items to be smelted
Hoppers attached to any side (including front or back) push into the furnace's inventory for fuel
Hoppers attached to the bottom pull from the furnace's output inventory
A simple but powerful example of hoppers in action is a bulk furnace. Rather than having to deposit and collect each stack of items you want to smelt, and regularly monitor the furnace's fuel, a bulk furnace lets you deposit a whole chest's worth of stuff and collect it all at once.
Bulk furnace
Hopper Minecarts
There is also the "Minecart with Hopper", or just "hopper minecart" -- a distinct item from the regular hopper! It's just what it sounds like: a hopper on wheels. It works just like a regular hopper, with a few key differences.
Hopper minecarts always have their output pointing down -- never to the side.
Hopper minecart unloading into a regular hopper
Hopper minecarts will only pull items -- they won't push them into another container. In practice, this means another container needs to pull items from the minecart, and the only things that can do that are other hoppers.
This hopper minecart has arrived at its terminal, but will not push items into the furnace.
Hopper minecarts also pull items from the blocks around them, not just above. And in addition to pulling items from the block of space above them, hopper minecarts pull items resting on top of the block above them. This is really useful for collecting items from automated farms!
This hopper minecart will collect the items on top of the white blocks.
Because hopper minecarts are entities, not blocks, they can't technically be powered ā they can only be activated or deactivated. They are deactivated when on a powered activator rail, just as regular hoppers are deactivated when receiving redstone power.
Droppers and Dispensers
Droppers and dispensers are redstone devices that store and output items.
Droppers and dispensers are both containers, meaning they have an inventory you can open and put and take things from, just like a chest.
If you want to place a block next to a dropper or dispenser, hold the sneak button (on PC, shift by default) before clicking to avoid opening the inventory instead.
Dropper / dispenser inventory UI
Droppers and dispensers both output items from their inventory. Items are output from the front of the block, which is the side that has the face on it.
The front of a dropper (left) and dispenser (right)
Droppers
When activated, a dropper drops an item on the ground, just as if you were holding an item and pressed drop.
Droppers drop an item on the ground when activated.
If a dropper is facing a container (like a chest, or another dropper) in the next block, it moves one item from its inventory into that container's inventory, just like a hopper's push. This isn't very useful now, but will be important in later chapters when combined with other techniques.
A dropper arranged to transfer items to another container
You can use droppers to build little conveniences around your base. Here's one being used for hoe storage next to a wheat farm, so you can grab a hoe for any repair work with a single mouse click.
Dropper being used as one-click hoe storage for a farm
Dispensers
Dispensers, when activated, try to do something with an object in their inventory, rather than just drop it. For example, dispensers will:
Equip armor directly on to a player
Shoot arrows
Shear sheep
Pour out a water bucket, creating a water source block
...and more. The Official Minecraft Wiki has a complete list of dispenser capabilities.
Dispensers are a key part of many devices, including wheat harvesters, wool farms, defense perimeters, and much more.
One simple example application of a dispenser is to deploy boats at a dock. Instead of having to get boats from a chest, a single click can deploy it in the water for you.
Boat deployed by a dispenser
Additional Details
Both droppers and dispensers activate only momentarily when going from powered to unpowered -- enough to process a single item. Leaving them powered doesn't do anything. If you want to output multiple items, you'll need to use a type of redstone circuit called a clock to automatically cycle power on and off. This will be covered in later chapters.
This won't do what you want it to.
If there are multiple types of items in a dropper or dispenser's inventory, a random slot is chosen each time it's activated.
This dropper has an equal chance of dropping stone or wood.
Like pistons, droppers and dispensers can also be powered by quasi-connectivity in Java Edition. This can be even more confusing with droppers and dispensers, since it's easy to visually tell if a piston is powered, whereas a powered dropper or dispenser gives no indication -- it just doesn't respond to additional power.
If your droppers or dispensers don't seem to be working, try relocating power sources and charged blocks a block or two further away.
Command Blocks
Command blocks are a powerful tool for Creative and Adventure modes. They can be programmed with console commands and chained together with basic logic to access many more of the game engine's capabilities.
Command blocks are a very big topic that may or may not be covered in future chapters.
The three types of command blocks
Chapter Summary
Entities
Entities are anything in the Minecraft world that is not a placed block.
Examples of entities include players, mobs, and items.
Entities are affected by physics, like gravity and water currents.
Doors, trapdoors, and fence gates
These mechanisms respond to changes in power, not the presence of power.
Regular doors, which are two blocks tall, respond to redstone power routed into either their top or bottom block.
Iron doors cannot be activated manually -- only by redstone power.
TNT
Powering TNT lights its 4-second fuse and turns it into an entity.
TNT that detonates while submerged in water won't destroy other blocks.
Note blocks
Note blocks play one musical note when powered.
The block above a note block must be empty to work.
Note blocks can play different instruments, determined by the type of block beneath them.
Manually using a note block tunes it to play a different note.
Rails
Activated powered rails accelerate moving minecarts when activated.
Activated powered rails routed into OCBs accelerate stopped minecarts away when activated.
Unactivated powered rails will stop a moving minecart in its tracks.
Regular rails at a T-intersection, when powered, will curve in the other direction.
Pistons and Sticky Pistons
Pistons (and sticky pistons) will push block(s) in front of them when powered.
In some cases, they will break blocks in front of them instead. This can be useful for building automated farms.
When sticky pistons retract, they also pull the block(s) in front them.
Pistons are subject to quasi-connectivity. If your pistons are activating when you don't think they should be, try moving power sources and charged blocks a block or two further away.
Hoppers
Hoppers are used to move items from one place to another.
Hoppers are containers.
Hoppers pull items from the block above them. It can either pull from a source container, or it can pull item entities anywhere in the block above it.
Hoppers push items into the block their output is attached to.
For containers with multiple inventories, which inventory the hopper interacts with depends on which side of the container it's attached to.
Hopper minecarts work like regular hoppers, except:
They don't push items.
They pull items resting on top of the block above them, and from blocks around them.
They can only be powered/deactivated by activator rails.
Droppers and Dispensers
Droppers and dispensers are containers.
Droppers and dispensers each output one item when they are powered.
When activated, droppers facing a container will push an item into that container, and droppers not facing a container will drop the item on the ground.
When activated, dispensers try to do something with an object in their inventory, like shooting arrows or shearing sheep.
Droppers and dispensers are subject to quasi-connectivity. If they don't seem to be activating when you think they should be, try moving power sources and charged blocks a block or two further away.
Next up: Power Sources!
Bulk furnaces, secret doors, simple cannons -- you can already build a lot of cool things with what you learned in this chapter. What else can you think of? What about an explosive trap? A doorbell for your home? How about a wheat harvester, or wool farm? Maybe a roller coaster? At this point, you've got all the tools you need to build those!
Redstone mechanisms are powerful because they enable your devices to do things to the environment. In the next chapter, we'll cover power sources, which are equally powerful, because they enable your devices to respond to the environment. More automated farms, storage management tools, and more await!