I think that redstone in Minecraft is quite confusing, so I'm learning about it. Then I came across redstone repeaters. I read about them and it says they repeat signals and can delay ticks. What does that do (and what does it mean)?
Repeating a redstone signal.
Think of a signal as in sending power to a redstone circuit.
Every redstone signal can travel up to 15 blocks before running out of power.
So basically every signal has a
power level of 0-15. A repeater resets the signal back to maximum power. That way you can extend the signal on redstone circuits that are longer than 15 blocks.
In minecraft, 20 ticks happen each second, so one tick happens every 0.05 seconds.
There is another type of ticks in minecraft, called a redstone tick.
Every redstone tick is equal to 2 game ticks(0.1 seconds).
Redstone ticks occur during redstone operations.
A repeater, by default, is set to one redstone tick (1/10th of a second delay). You can set it(by right-clicking it) up to 4 redstone ticks (4/10 of a second or 0.4 seconds).
Why would you want to add delays to a signal?
Lets say you made a redstone circuit that activates and deactivates all the redstone lamps in a tunnel, and you want each set of lamps to activate/deactivate with an 1 second delay between each set. You would need to add 2 repeaters on 4 ticks and 1 more repeater at 2 ticks for a total of an 1 second delay.
Obviously, this a very simple way to use redstone repeater delays, but you understand the concept. Delays can be used for redstone clocks, pulse generators and lots more.
More information on the above:
The delay just increases the time for the propagation of a redstone signal which can be anywhere from 1 to 4 redstone ticks. A redstone tick is defined as:
A redstone tick describes two game ticks. This creates a 1/10 of a second delay in the signal of a redstone circuit. That is, the signal's time to travel from a location A to location B is increased by 0.1 seconds. A tick only pertains to the increase in signal time, thus, a signal's travel time can never be decreased in reference to ticks.
You can use this delay to your advantage to create things like a clock signal, pulse generators, or just use it to have different components react at different times like having having one dispenser fire 0.5 seconds after another. There's a lot that's possible so just play around with it and see what you come up with.
Synchronization and general delays are one thing, but a clock circuit is actually very important. There are blocks that activate on redstone input not constantly, but "on edge", i.e. when it changes from off to on. Most notably droppers and dispensers.
The easiest way to create a pipeline for transporting items upwards (and cheapest that transports in any other direction; hoppers cost a lot of iron) is to line up lots of droppers and power them up with a clock signal.
Another application is with dispenser that doesn't hold any backlog of items: a redstone event is triggered before the item is gathered by a hopper, then deployed by a dispenser fed from that hopper - you need a delay before triggering the dispenser (example: my automatic cow butchery which uses a cactus to break a cart and eject the cow before redeploying the cart.)
with a redstone repeater, if the two torches are the closest together, it will have 0.1 sec delay, if the moveable torch is close to the nonmovable one but is close to the center that is a 0.2 sec delay, if they are far away but the moveable one is still close to the middle its a 0.3 sec delay, if they are the furthest away posible thats a 0.4 sec delay