This Design is completely overflow proof. The storage could be full, the sorting hoppers could be full, DOESN'T MATTER. It is absolutely unbreakable. It also costs very little and is 1 wide and infinitely expandable.
It uses a rare redstone mechanic:
A comparator will output signal from a container through a full block EXCEPT
when the full block has signal strength of 15. If the full block has signal strength of
15, the comparator outputs 15.
Advantage over Impulse's 3-dust design:
1) less dusts, less lag.
2) a lot less accidental breakage due to nearby power sources interfering. (less to worry about)
You can build circuits in close proximity.
3) shorter, if you don't count the furnace.
1) costs 2 quartz and 4 sticks more. that's it
Side View (The Furnace can be replaced with Any EMPTY Container, but it MUST be there)
Note, the two comparators in a row is necessary to prevent torch burn out due to rapid pulsing.
Example of a middle Hopper:
How does it work? Here is step by step:
1. An item gets sucked into the middle hopper.
2. By step one, the middle hopper is completely full.
3. The comparator connected to the Hopper outputs 15.
4. The signal strength of 15 reaches the block below, triggering the rare mechanic,
which turns on the bottom comparator which allows the bottom hopper to suck one item from the middle hopper.
Why is it overflow proof?
Because the redstone dusts cannot have more than 15 signal strength, one sorter does not interfere with adjacent ones.
What happens if the sorter is full?
Nothing! The item will simply continue down the top hopper line.
This is a cheap and effective design, which will come in handy in a lot of situations. It could effectively replace most sorters.