You will need 19 items of what you want to sort, 1 Redstone repeater for each item sorter. You will also need 2 Redstone, 1 or 5 comparators, and about a stack of hoppers and chests along with some Redstone lamps depending on which sorter you make. If you make a sorter with Redstone lamps, they will tell you how many double chests full of items you have in the chest which can be very useful. Now how to build it.

Step 1. First make your hopper chain. A hopper chain is hopper all going into each other directing the items.

Step 2. Make a hopper underneath you hopper chain. Have it facing into nothing. Underneath that hopper have a hooper going toward where your chests are.

Step 3. This is where the Redstone comes in. Have a comparator coming out of the hopper underneath the hopper chain. Have your 2 Redstone dust coming out of the comparator. Then take the one repeater and put it underneath the 1 redstone dust leading into a block with a Redstone torch underneath the 2 hopper. As shown above in the picture.

Step 4. Now this is where the items come in. In the first hopper put 18 of your item in the first slot of the hopper. Then fill the rest of the slots up with renamed rotten flesh or something you have a lot of. don't stack the renamed item, just put 1 in each slot. Then put the last item you want to sort in the hopper on top of the redstone torch.

Step 5. Then put your chest from the hopper. you have now made your minecraft auto sorter. If you want a lamp, have a comparator coming out of the chests leading into your lamps.