User:L4bbogdanbarbu/Item-sorting silo

The following is a design for an item-sorting silo. It's flexible in that it can be extended to handle any number of item types and allows the silo to be extended along two axes to increase its storage capacity. The author suggests using item frames above each chest on the bottom layer to inform users where each item type should be searched for.

Construction
The length of the top hopper layer should be equal to the number of items handled by the system. Note that the first hopper in the following schematic is the most efficient one to handle random items in the particular configuration showed here.

The schematic below represents a vertical slice of the system. Slices can be stacked and there should be one per handled item type. The highlighted hoppers on the top row represent two hoppers described in the previous schematic. In particular, they show two hoppers from a middle slice of the mechanism. However, the hoppers on the far sides should be oriented as shown in the schematic above.

The item item distribution in the hoppers on the second layer is 1, 41, 1, 1. Whichever item is used decides the item type to be selected for storing in the chests on that slice. The hoppers immediately below them must also each have an item inside; if the item is of a different type, it should not reside in the first slot.

To extend the silo horizontally, simply place as many hoppers as required along the top and bottom layers of the silo, as shown in the schematic. To extend it either horizontally or vertically, copy the 3 &times; 2 area immediately below the top hoppers to fill in the remaining space.

Since chests of the same type cannot be placed right next to one another, chests and trapped chests are used in alternation. All chests on a vertical slice are of the same type.

Explanation
The mechanism has two main parts: an item sorter and a silo.

Item sorter
The top layer is a hopper circuit whose purpose is to cycle through any unsorted items. There are two reasons why this can be useful. First, because there might be no dedicated storage for particular item types; such items would remain in the system until said storage is provided. Secondly, because hoppers might push some items before the hoppers under them have had a chance to pull them; such items can be handled safely in future cycles. As mentioned above, the first hopper is the most effective when sorting random items. The reason for this is that items get cycled right into the beginning of the sorting process. Should they miss their hopper, they eventually return to the first one and start the process over.

When the item sorter is in standby, the hoppers on the second layer contain just enough items to unpower the hoppers below. Since their items have nowhere to go, they will simply sit there until at least one more shows up, powering on the hopper below, which will start pulling the extra contents. As soon as the initial treshold is reached, power is cut off again. Note that since all slots are occupied, wrong items can never enter. Furthermore, hoppers attempt to use their slots in succession starting from the leftmost one.

The length of the redstone wiring ensures that adjacent hoppers would require more than their maximum load for the signals from their comparators to reach neighbouring repeaters. Thus, they can never acidentally block a hopper on a different vertical slice.

Silo
The top hoppers from the silo part of the mechanism push items from left to right while hoppers below them attempt to pull them. Items then attempt to travel towards the bottom and then towards the leftmost chest.

FIXME

 * Not yet sure how "small stacks" (e.g., 16 eggs) are weighed.
 * Overflowing is unlikely but can actually still occur, despite my previous claim. Possible solutions include different wiring and using items that are never sorted (e.g., named cobblestone) in slots 2--5.