been playing around with redstone again until i discovered this strange beviour:

I used to droppers on top of each other and a chest on top of that to transport some items from the bottom dropper to the chest on top. The bottom dropper has a comparator attached to it doing all the logic for the elevator. The Redstone looks like this:


D = Dropper C = Comparator R = Redstone E = Repeater

It is the most simple possible item elevator. The Redstone shown above powers BOTH droppers which are on top of each other and thus makes it possible to transport all items vertically since you can stack this thing endlessly.

Now to my question: When the Comparators are on the North side of the Droppstower it doesn't fully work, when they are attached to the South side it does work as intented.

What do i mean by saying "It doesn't fully work"? Once all items are done being transported and the redstone mechanism stopped because no items are left in the bottom Dropper, there is one item left in the top dropper while N-1 items are in the chest. - On the other side when puting the comparator on the South side, all items are transported to the top - not one getting stuck at the end of the top dropper.

Is this a bug? Why does this happen?

Thanks a lot! :-)

  • It's probably due to the South-East rule, whereby certain redstone (and other) mechanics "prefer" the southerly or easterly direction. Another (although less likely) possibility is that you built your contraption on a chunk boundary, which can do odd things to redstone.
    – MBraedley
    Apr 6, 2014 at 18:26
  • @MRraedley: Yes i know about that rule. The problem is: the article doesn't really talk about the rule affecting redstone - therefore it wouldn't be something the rule does affect. So it would be a bug. Correct? If yes we should report it at the bugtracker. And no, it is NOT about chunk boarders - i tried that several times in Singleplayer - this is not caused by chunk boarders. It is only caused by South / North!
    – Shiuyin
    Apr 6, 2014 at 18:53

1 Answer 1


This is due to the South-East rule. Despite a lack of mention in that page, this quirk does affect redstone. What's happening is that the dropper on top receives an item from the bottom dropper before it's instructed to fire when the comparator is on the north or the west sides of the droppers (opposite to what you said). When the comparators are on the east or south sides, the redstone power is cut before the top dropper is instructed to fire for the last item.

But it's more complicated than that. It's not just where the comparator is placed in relation to the dropper, but also where the rest of the redstone is placed. I've set up the same elevator, but mirrored, and it no longer emptied the top dropper.

My suggestion would be to either use a different item elevator, or find which of the 8 versions is going to work best for you.


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