If I have a powered hopper with items in it, and I want to let one item through, how long do I have to un-power the hopper? 1 or 2 ticks? All I know is that a hopper transfers items at the rate of 2.5 items per second. Any help is appreciated 🙂 And is there a different amount of time on Bukkit servers?
Minecraft – How many ticks must I use to get only one item through a hopper
minecraft-bukkitminecraft-java-editionminecraft-redstone
Related Solutions
This is the intended way of operation. As both hoppers try to push their first item each way, only one ends up moving.
To make hoppers pass the whole load before starting to pass it back, you need to block the next (opposing) hopper until your current one is empty. The standard way (that you mention yourself) is measuring the contents of the current hopper with a comparator, and feeding this signal into the next hopper.
Here's SethBling's hopper clock from Minecraftwiki:
Hoppers are directed clockwise, right now the items are moving from top left hopper to top right one, which is still locked by a signal from top comparator, and is already sending a lock signal to bottom right hopper.
For more designs, see this section on the wiki.
As with most counting problems in Minecraft, the answer is eggs.
Take a look at my sample setup.
Redstone explanation
To the right, we have a monostable circuit to shorten the input (the button) down to 1 tick. I use Sethbling's favored design, the repeater is set to 3.
The Centerpiece is a Hopper-Dropper-Counter (a hopper and dropper pointing into each other), containing, in this case, 9 Eggs (or anything that stacks to 16) and 10 Cobblestone (or anything that stacks to 64), for a total of 19 items. You realize this is 1 short, but that's actually fine.
The comparator turns to 3 when all items are in the hopper. In this case, the torch at the bottom of the picture turns off.
The last component is a Repeater-Lock. On each button press, the hopper will update to whatever redstone signal is on the bottom torch before the button was pressed. So if it's at three bars after 19 clicks, it will unlock the hopper on the 20th click, causing all items to go back into the dropper.
To make something happen every 20th click, you should get the signal from the block next to the hopper (i.e. the state of the locked repeater), it is only ever off 1/20 of the time. You could put redstone dust underneath, or put a torch on top, for example (but watch out for signal inversion).
Design notice: I used a variation of this for a three state enchanting room (lvl 1, lvl 18, lvl 30 enchants), using 2 wooden swords, and repeaters checking for a signal >0 and >3, respectively.
Best Answer
Pistons also have a .5 tick on the end. the game gives off-tick checks to increase speed, to there are 2 game-ticks in every redstone tick. Therefor 8 game-ticks, or 4 redstone ticks.