I've been using "hopper timers" to create long delays for some automated harvesters, using what seems to be a pretty standard method with comparators. So far this has been working well. But for the past few days I've been unable to build a new one.

When I start with the two mutually connected hoppers, I test them by dropping a stack of items into one of them to make sure it moves back and forth. But now any new such pairs of hoppers I create only move one of the items back and forth over and other, leaving the rest of the stack in the original hopper.

I've checked my existing ones and they're still functioning as designed. But any new ones seem to suffer this problem of not exchanging all of the items. Is there something I might be doing wrong?

Edit: As requested, here's a screenshot of a hopper pair: enter image description here And here's one of the right-side hopper's contents: enter image description here In this case, there are 10 redstones placed in the right-side hopper. That hopper keeps toggling between 9 and 10, and the left-side hopper keeps toggling between empty and 1.

  • Can you post some screenshots?
    – Lars
    Dec 21, 2013 at 15:28
  • @Lars: Added. There isn't even any additional mechanism to the timer at this point, just the hopper pair.
    – David
    Dec 21, 2013 at 15:35
  • Are you saying in other instances the same setup works? It shouldn't work without a comparator.
    – Orc JMR
    Dec 21, 2013 at 15:38
  • Well, these two hoppers behave correctly. Since neither of them is being powered, they're funneling items into each other.
    – Lars
    Dec 21, 2013 at 15:46
  • Interesting. Essentially I've been referencing this video: youtube.com/watch?v=bYwzd62cLSw And this same behavior is happening on the smaller piston-based timer. The larger one still works, I just re-built it and it's working.
    – David
    Dec 21, 2013 at 15:49

1 Answer 1


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:

Hopper clock

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.

  • 1
    Ah, that's the key. Powering the next hopper until the first one is empty. That's the detail I was missing. My smaller timer is working now, I was just feeding the wrong hopper at start-up. Thanks!
    – David
    Dec 21, 2013 at 15:53

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