Weighing Puzzle

one item is lighter one item has differing weight Start new Puzzle

The Scale:  ? 

Weigh 0 weighings

The aberrant item is:

You have a number of items. One of them has a different weight. Try to figure out which it is with as little weighing attempts as possible.

For example 9 items with one lighter in 2 attempts,

Or same but with unknown aberrance (lighter/heavier) in 3 attempts,

Or 12 items in 3 attempts...