Today you will learn the basics of redstone, the electricity analog in Minecraft. Redstone behaves in reference to certain rules that are predictable and manipulable, just like in real life. The realm of redstone mechanics is nearly endless, and today you will gain familiarity with some of the fundamental processes of redstone: Signals, transmission, repeating, and component use.
What can Redstone do?
Redstone can perform any number of tasks, from simply turning on a light in reference to a lever to recreating RAM and full pixel displays. The difference between these two projects is that of their complexity, not their component use. Whether you are wiring your house of playing a game of snake, Redstone depends on some fundamental concepts and blocks to work. With time, you will gain command of these concepts and be well on your way to creating unique and elegant Redstone machines. I use the term elegant to describe your future builds because, as will all computing systems, there is an "elegant" solution and a "working" solution. In later episodes, we will focus on the necessity of finding efficient, speedy, and applicable solutions to your particular Redstone desires. Keep this idea in mind as you start to explore Redstone circuitry.
One of the most important attributes of Redstone is Signal Distance, which refers to the number of blocks a single Redstone input can travel before fading. From the power source, a Redstone wire can be laid without interruption 15 blocks in a row before the signal on the end no longer exists. As the signal travels farther from the power source, its bright red "on" color starts to darken. By the 15th block, the shade of "on" Redstone is very similar to "off" and can be identified mostly by the smoke coming off of the wire. Don't worry, the smoke is a positive thing. It is another indicator that that particular Redstone wire is powered.
In the EML World, I have constructed a series of lights to demonstrate this concept. Each light within 15 blocks of the power source can be seen to turn on when the lever is flipped whereas the final light at the end of the string does not. This concept is directly applicable to the real world, for cables like Ethernet can only be a certain length (roughly 328 feet) long before losing their signal.
Laying Redstone horizontally is easy enough, only requiring that a block be beneath. Vertical translation of Redstone is a little more involved, requiring the use of a "Redstone Ladder." A ladder is the blanket name given to any block pattern that allows a Redstone signal to move up or down a layer of blocks. In this lesson, I will present four kinds of Redstone Ladder: The Stair, Glowstone, Ascending Torch, and Descending Torch Ladders.
The Stair Ladder
The Stair Ladder is the most common ladder in Redstone. Consisting of a series of diagonal blocks, the Stair ladder is able to transmit signal both up and down quickly. The only downside to the Stair ladder is the space efficiency. At a minimum, the Stair ladder requires four blocks of horizontal space, significantly more than some of the other ladders. Its simplicity and flexibility are king though, making it the most important ladder of these four.
The Glowstone Ladder
The Glowstone Ladder represents the fastest means of transmitting a redstone signal upwards. Comprised of a two-wide checkerboard pattern of Glowstone, this ladder can transmit a signal instantly as many as 14 blocks vertically. However, the Glowstone ladder can only be used to transmit Redstone signal upwards. The ladder occupy only 2 blocks of horizontal space, making it the second most space efficient upwards ladder.
The Ascending Torch Ladder
The Ascending Torch Ladder represents the most space efficient ladder of the four. Occupying only a single horizontal block, this ladder consists of a stacked pattern of Block, Redstone Torch, Block, Torch, and so on. However, because of the way Redstone torches interact, the details of which we will get into in the next lesson, this ladder is relatively slow, introducing a 1/5th of a second delay for every redstone torch in the tower. Also, this ladder will only produce a corresponding signal (on=on or off=off) every other step of the ladder. Therefore, some additional redstone manipulation is required to fully utilize this particular ladder. If space efficiency is the concern however, the Ascending Torch Ladder is the ladder of choice.
The Descending Torch Ladder
The descending Torch Ladder represents the most space efficient means of transmitting a redstone signal downwards. Occupying only two horizontal blocks, the ladder consists of a repeating pattern of Block, Redstone dust, and Redstone torch (see below) to transmit signal downwards. Seeing as this is a torch ladder, the same attributes as the Ascending Torch Ladder apply, i.e. slow signal transmission and an offset corresponding signal. Besides the Stair Ladder, the Descending Torch Ladder represents the only other means of transmitting a signal downwards.
The Redstone Repeater
The Redstone Repeater is a very powerful block readily available in the game. With the addition of some quicks, the Redstone Repeater performs three primary tasks: signal extension (repeating), programmable signal delay, and controlling the flow of signal (as a Diode).
Repeating a Signal
Most Redstone projects require that you transmit a redstone signal farther than 15 blocks. A redstone signal is extended by a block called a Redstone Repeater. This flat block is placed at any point in an energized redstone wire to repeat the signal and begin a new count of 15 blocks. This is particularly useful if you have built a glowstone or stair ladder that needs to go higher than 15 blocks.
Another powerful function of the redone repeater is its ability to introduce a programmable delay into any circuit. The standard time unit of minecraft is one "tick" or about 1/5th of a second. When a repeater is initially placed, it has an innate delay of one tick. By right clicking the repeater, the rear torch can be seen moving away from the front torch. This is the visual representation of adding a tick to the delay. Right clicking a single time will program the repeater with two ticks. Two clicks will program a three tick delay, and so on until you have right clicked three times, programming the repeater with its maximum delay of four ticks. Right clicking the repeater again will start the count over at the innate value of a one tick delay. Placing multiple repeaters in a row is additive, allowing you to program any number of delay greater than a single tick. The delay also applies to how quickly the signal is turned off. For every tick that is programmed into a circuit, the signal will be delayed both turning on and turning off by that value.
Governing Signal Direction
The final function of the Redstone repeater is its ability to control the flow of Redstone signal. Upon examination of the redstone repeater block, a faint, very pixelated triangle can be seen with its point at the stationary torch. This arrow describes the direction a redstone signal is allowed to flow through the repeater. You can predict the direction a repeater will face, for the arrow will point in the same direction you (the player) are facing. If you are looking in the direction of the sun and place a repeater, the repeater will point towards the sun. Placing a repeater backwards shuts off any strength of redstone current. This function most closely mimics that of a diode.
Conductors and Insulators
As in the real world, blocks in minecraft can be divided into Conductors and Insulators.
Conductors make up most of the blocks available in Minecraft. The stone pathway you are walking on in the world or the wood that the spawn is made out of are two examples of conductors. Conductors allow a redstone signal to pass through them, acting as a one block long redstone wire. This is particularly useful if you want to hide a power source (like an outlet!).
Insulators have three special qualities that separate them from conductors. Insulators do not allow redstone signal to pass through them. If placed in the same way as a conductor, the insulator will stop a redstone signal as if there is no connection.
Insulators will also not interfere with a connected redstone circuit. In the example in the lesson, a piece of glass (one of the most common insulators) is observed allowing a redstone signal to ascend uninhibited. If a conductor was placed in the same location, the redstone wire would be cut and no signal would be allowed to pass through. This is particularly useful for circuit protection and hiding.
Finally, insulators are not receptive of redstone components. Redstone dust, redstone repeaters, levers, buttons, and pressure plates cannot be placed onto insulators. There is only one instance where this is not true and that is...
Glowstone is the only insulator that will receive a redstone component. As demonstrated by the redstone ladder, Glowstone will allow redstone dust to be placed on top of it. This, paired with its non-conductivity and that it does not cut redstone wire are what make glowstone so useful in redstone projects. The details of all blocks including glowstone, are available on the Official Minecraft Wiki. I encourage you to experiment with as many blocks as you can to determine their conductivity.
In addition to redstone dust and repeaters, there are myriad blocks that specifically require redstone interaction.
Input devices allow the player to interact with a redstone circuit. You have already experienced buttons, levers, and pressure plates. Buttons and pressure plates come in either wood or stone (the difference is the delay they stay on). In addition to these, there is the tripwire. A tripwire is placed one block above the floor and strung with string to create a "wire" that the player can walk over to activate. This is particularly useful in mini-games and user-dependent machines because they can completely cover a particular path.
Another input device that does not depend on the player is a daylight sensor. This sensor will detect the ambient light level of a location and output a redstone signal of corresponding strength. This will be particularly applicable much later in the series when we begin to model sustainable processes in reference to the sun.
There are two type of kinetic block manipulators. The Piston and the Sticky Piston allow you to move a stack of blocks one position in reference to a redstone signal. The sticky piston will retract the block touching the piston head when not power whereas the normal piston only pushes. The maximum number of blocks a piston can move is twelve. However, there are some immovable blocks such as obsidian and furnaces that a piston will have no effect on.
The Redstone Lamp
The Redstone Lamp functions exactly as you would think. In reference to a redstone signal, the lamp will turn on and off, producing light. By another quirk, a powered redstone lamp will also power all of the blocks touching its faces, creating a star pattern if the center block is powered. The specific light levels produced as well as its other attributes can be found on the Official Minecraft wiki.
The Note Block
The Note block is a programmable block that will produce a single beat at the specified pitch when powered by a redstone signal.
Dispensers, Droppers, and Hoppers
Dispensers, Droppers, and Hoppers all deal in the transportation of "drops" or the transitory state of all blocks between placement and your inventory. When powered, a dispenser will expel whatever block is placed inside of it (use right click to open its inventory). If the object inside of the dispenser can be fired, it will do this rather than spitting out the drop. This applies to arrows, snowballs, and fireballs. The dropper functions similarly to the dispenser, but will only ever expel the drop form of the block. The hopper allows drops to move between hoppers, droppers, chests, and furnaces by sucking the drop in through the top and spitting it out of the bottom tube. The specifics of how to place hoppers and properly connect them are available on the Minecraft Wiki. We will be dealing later with some special features of Hoppers.
Power Source Blocks
Power source blocks are the only blocks in the game besides user input components that provide a redstone signal.
The Redstone torch provides a constant output signal of 15 (signal strength 15) that can be turned off and on by powering the block it is placed on. This function becomes particularly important in later episodes.
The Redstone Block is a solid block of redstone that provides a constant signal of 15. The block cannot be turned off and powers all surrounding blocks as well. This is the only redstone component that can be moved by a piston.
The final redstone component is the comparator. This little device is immensely powerful performing multiple computational and detection tasks.
The comparator is a block that looks very similar to the redstone repeater. When placed, the comparator will face in the same direction you are. On the top of the flat block are three redstone torches at each of the vertices of the triangle. These three torches describe the various sides of the redstone comparator. The first side, called the "A" side is the face parallel with the two bottom torches. The "B" sides are to either side of those torches. The "C" side is parallel to the face with the single torch. This side is the output of the compared signal. A and B are inputs. The Minecraft Wiki goes into more detail on these sides and their function. I also walk through the use of Redstone Comparators in the third video of this lesson.
The first function of the Comparator is its namesake ability: comparing two signals. When inputing a signal into the A side, it is compared with a signal detected by the B side. If A > B, the A signal will be allowed to pass through. If A < or = B, the signal will be stopped. When a signal passes through a comparator, a one tick delay will be introduced and an output signal of strength equal to the A input strength.
Subtraction mode performs a particularly complicated comparison between the A and B inputs. To change the comparator into subtraction mode, simply right click it. The front single torch will turn on telling you that the comparator is now in subtraction mode. In this instance, the comparator will perform the operation A - B = C, outputting a signal of strength A - B.
The comparator is used to detect an attribute of a block. Most commonly applied to chests, droppers, and dispensers, the comparator will output the a signal strength of the number of slots filled within each block. If one row of a single chest is filled with blocks, the comparator will output a single of 5, or 1/3rd of 15. The Official Minecraft Wiki goes into much more detail about the intricacies of the comparator. I also walk through all of these functions in the 3rd video as I mentioned before.
What You Have Learned
Today you were introduced into he fundamentals of Redstone, the Minecraft analog of electricity. You approached the idea of elegant and working solutions and observed a few examples of Redstone circuitry. You saw that a Redstone signal can only travel 15 blocks at a time before being repeated, and in order to transmit that signal up or down, you must use one of four ladders. You learned that repeaters can extend a signal, introduce a programmable delay, and act as diodes in a redstone circuit. You experimented with Conductors and Insulators, exploring the specific attributes of both and discovering the unique properties of Glowstone. You met all of the members of the Redstone component family, including tripwire, pistons, and dispensers as well as approached the concept of a power source block. Finally, you explored the power of the Redstone Comparator, using it to Compare, Subtract, and Detect various signals and blocks. All of that information is now at your command, for you are fully equipped to start developing your very own redstone projects. In the next few lessons, I will explore some more redstone circuits that will really take your redstone building to the next level. But, until then...