Minecraft wiki entry for Transmission, associated text: Observers can also be used to create a vertical ladder. Each observer carries block updates to the next observer up or down. A more advanced observer wire can be made by alternating, in upward order, observers, solid blocks, and either hoppers (only in Java Edition) or Droppers (in any edition). Each observer powers the dropper/hopper above it through the solid block, which changes its block state, activating the observer above it. The blocks can be removed to make a wire that is slower but does not power anything next to itself. Any of these can go horizontally or downward as well. There is also a more efficient downward method that goes (in downward order) observer, solid block, redstone dust, solid block, hopper/dropper.