Now that you’ve been playing Minecraft for a while, you probably want to start building something involving redstone. At first, redstone construction may sound overwhelming, but once you understand the basics, it’s a lot less complex than it first appears.
Redstone is the Minecraft equivalent of electronics, but with a few differences. We’ll start first by discussing how redstone works at a basic level:
In order for a redstone circuit to do anything useful, it must have three parts: Input, Transmission, and Result. The input is some form of interaction the player has to get things started, the transmission then takes the signal to the result, which makes some change in the game world. Before we get into the input, we should however, understand how the signal is transmitted, as this is actually the most important part.
There are two main ways to transmit power from one area to another with redstone: redstone dust and powered blocks. Redstone dust is placed on top of a block and visibly glows when powered. It can only be placed on opaque blocks and only if there are no other block modifiers in the space above the block. This means ladders, signs, rails, fences and torches will block you from placing redstone dust on a block if they are at the same level. Like torches, water will wash away redstone dust, so be sure to protect your circuits from accidental water sources. A powered block is just an opaque block which has had power applied to it in some way. A powered block can power adjacent redstone dust, an adjacent redstone device, but cannot power an adjacent block. Redstone dust will power any adjacent blocks, redstone dust, redstone devices as well as powering the block it is resting on.
For each block a signal travels, it loses 1 power level from it’s original strength. Most sources of redstone power start at a power level of 15, so the power can travel 15 blocks before it loses all power and must be renewed. There are a variety of ways to do this, and each have their own advantages and disadvantages. We will get into those later.
The two main sources of power, other than actual input systems, are redstone blocks and redstone torches. A redstone block, is an always on form of power. It powers adjacent components and dust, but does not power adjacent blocks.
While this can be useful, it doesn’t offer the flexibility of a redstone torch. A redstone torch, is a redstone power source which can be turned on and off.
A redstone torch can be placed the same way any regular torch can and will power any adjacent redstone dust, as well as the block directly above it. If the block it is attached to is powered, it will turn off the redstone torch. This is extremely useful in two ways: inverting a power signal or transmitting power vertically.
Redstone dust can climb up a block, but only if there is open space adjacent to where it will be climbing to.
This means that a block directly above the redstone dust will stop it from climbing up a level, which forces vertical power transmission with dust to spread out horizontally as well, making a stair approach. One solution to this stepping stair issue, if the power needs to travel upwards, is to place a torch and block alternating on top of each other. This may invert the power signal when it reaches the proper height, however, so it is important to determine what you want the input and output to be and adjust it accordingly. If traveling downwards with power, you have no choice but to use the stair method.
It is also important to note that you can create a feedback loop with redstone. For example, the pictured setup will cause one to occur.
What happens is that the redstone torch attached to the block powers the block above it. This in turn powers the redstone dust adjacent to it. That powers the block it is resting on, which also happens to be the block the redstone torch is attached to. Since a redstone torch attached to a powered block is turned off, the torch turns itself off. When it does, the block above it is no longer powered, and the redstone dust becomes unpowered, and the block with the torch becomes unpowered, which allows the torch to turn back on, and the whole thing starts over. When a feedback loop like this happens, you will see the circuit and the torch flash for a second, and then hear a sound like a fire being extinguished, and the torch will unpower until the circuit changes. While there are uses for such a feedback loop at times, sometimes it’s undesirable, so one way to fix this if it becomes a problem is a circuit like this the one pictured.
By using a torch on the powered block, you can apply power to a redstone circuit without powering the block the other torch is applied to. You may need to invert the signal later in the circuit, but this is preferred over the feedback loop. The other option is to have the redstone dust going in a direction away from the redstone torch, so it doesn’t affect that block.
In order to have a redstone device do anything, you need some kind of interaction with the outside world. There are several different ways this is accomplished. All of these devices will power at level 15 any adjacent dust or devices, unless otherwise stated. So let’s go through the devices quickly:
A lever is a simple on/off switch which toggles powering the block it is attached to.
A button is a device which powers the block it is attached to briefly before turning off.
A pressure plate is a device which powers the block it is attached to, for as long as something is on top of it. There is also the weighted pressure plate which counts entities on top of it, and outputs a signal based on how many and which type of weighted pressure plate it is.
A tripwire powers the blocks it is attached to as long as something is in the tripwire.
A detector rail is similar to a pressure plate, but only detects when a minecart is on the rail.
A daylight sensor will detect when natural sun light hits it and powers adjacent dust to a level based on how much sun is hitting it, or how dark it is, if the sensor is inverted.
A trapped chest is similar to a normal chest, but will power the blocks it is resting on when the chest is opened.
It Gives Results
Now that you know how to start the signal, and how to transmit it, you will need somewhere for it to go. There are many things that will react to redstone power, and here is a list of all of them:
Pistons are one of the post popular uses of redstone. They will push up to 12 blocks away from the piston in the direction the piston is facing. Sticky pistons will also pull one block back when they retract. They are most often used in trap doors and secret entrances, as well as ways to interrupt or start a circuit. This will be explained later.
Dispensers can be used in several different ways, depending on what they are dispensing. They can fire arrows like in Indiana Jones movies, pour out lava or water, even put out a minecart. The Minecraft Wiki goes into great detail on the subject of how each item will be dispensed.
Droppers are similar to dispensers, except that they will just place the object they are dispensing next to drop hole. If the objects is affected by gravity, it will fall, if not, it will just sit there.
Redstone Lamps will produce light when applied power. They are useful as either a visual display that a circuit is working, or for making visual effects.
Powered Rails will increase the speed of a cart moving on the rail in the direction it is going.
Curved rails, if they have another option to curve towards, will change direction between when powered and unpowered. This can be used to have an automated rail switching system.
Activator Rails will perform various functions, depending on the type of minecart which is resting upon them when powered. The Minecraft Wiki has a full list of all results for each minecart type.
Doors will open when a signal is applied to any of their blocks, as will wooden fence gates, and trap doors.
Note Blocks will create a sound when activated, and can have different sounds based on what is around the block.
TNT when powered, will become primed, and explode not long after that. In this way, you can use redstone to create a fuse, to be a safe distance, or even as part of a trap.
Hoppers react opposite of most items powered. Instead of doing something when powered, a hopper will cease to do it’s normal function when powered.
There are some very basic circuits which are commonly used. Placing a redstone torch next to a powered rail, for example, will keep that rail powered all the time. Putting a lever, button or pressure plate next to a door or gate will make an easy door opening mechanism. While these do utilize redstone, they are only the most basic of systems, and require little to no interaction from the players. In fact, some of the systems will work even if a monster activates them.
As mentioned previously, there are ways to renew a redstone signal that is getting weak. This leads us to one of the two advanced pieces in minecraft redstone circuitry, the repeater.
This handy device functions in several ways. It is important to note that the device acts as a diode, only allowing a signal in one direction, depending on how you place it. The second way is that it boosts a signal back up to full 15 strength. Also, the repeater can be set with a delay. By default a repeater has a .1 second delay, but can be set up to .4 seconds by using it, which is especially handy for note blocks. Any signal that ends will continue to be transmitted for that delay. In this way, you can make a circuit which remains on for a brief while after the power is terminated. For example, you can have a button which opens a door, and remains open long enough to get through.
Another aspect of repeaters is when a redstone repeater or comparator points at the side of the repeater and is powered. When the side is powered like this on it’s side, it is locked in it’s state, whether that is turned on or off. This works great as a way of locking an output to keep a short burst signal and keeping it on.
The second advanced piece is the comparator. This is a lot more complex of a device, so let’s go into how it behaves. First, let’s examine it’s appearance. When placed, it will place the front away from the player. The front has one redstone torch, and the back has two, forming a triangle pointing to the front of the device. The front is the output, and all the other sides are inputs.
When no powered inputs go into the side of it, the output will just relay the rear input signal normally.
By ‘using’ a comparator, you can toggle between ‘compare’ mode (front torch lowered and off) and ‘subtract’ mode (front torch elevated and on).
In Compare mode, if either side input is greater than the rear input, the output will turn off, otherwise it will just relay the signal at the current strength from the rear input. In Subtract mode, it will subtract the highest side input from the rear input, and output that, with a minimum 0 strength. So say the two sides had a signal strength of 4 and 2, and the rear input was at signal strength 10. The comparator would output a 6 signal strength.
Not only that, a comparator has another handy trick which allows it to do more than just compare and subtract. Certain blocks in the rear input spot will output a signal to it at a certain strength based on the blocks’s state. The blocks which can be measured this way may have a block between them and the comparator, so the wiring can be hidden. The most common things that can be measured are containers, which will output a signal strength based on how full they are. Other items which can be measured are cakes, cauldrons, end portal frames, item frames and jukeboxes. The Minecraft Wiki has details on what strength is output based on containers or other factors.
As mentioned before, pistons themselves can act as part of a redstone circuit. For example, a piston can move a block into a position to cut off a circuit from climbing up a level. Other uses have a redstone block being moved by piston, powering different circuits entirely. As a redstone block is the only source of redstone power which can be moved by piston, this makes it useful in such regards. Torches will be removed if the block they are connected to is pushed in any way.
With a these devices, some very complex systems can be made. I personally have a potion brewing system which makes potions based on which levers are toggled, several trap door systems, a mine cart dispenser and recycling system, and even an automated mincer transportation system to get items to a different location. There are even more complex systems which re-create a computer, allowing you to type on a keyboard made of pressure plates, and have the letter appear on a huge computer screen, working calculators, multi-level elevator systems and more.
One thing that helps when making a system is mapping out what you want signals to do, like a logic circuit. Once you have that planned, you just need to work out wiring. A collection of useful mini-circuits can be found on the Minecraft forums. With these, and a good plan, the sky is the limit as to what you can create! You can also pick up the sweet t-shirt used as our title image over at J!NX.