How to Make an Observer in Minecraft and How It Works

An observer takes 6 cobblestone, 2 redstone dust and 1 nether quartz. On a crafting table, fill the top and bottom rows with cobblestone. In the middle row, put redstone dust in the left and center slots and the nether quartz in the right slot. You get one observer.

The order of the middle row matters. If the recipe doesn’t appear, check that the quartz is on the right and both redstone dust are to its left.

Getting nether quartz

Quartz is the only part that needs a trip. Nether quartz ore is all over the Nether’s netherrack walls, and any pickaxe mines it. One ore gives one quartz, plus some XP. A few minutes after stepping through a Nether portal you’ll usually have enough for a stack of observers.

How an observer works

An observer watches the single block in front of its face. When that block changes state, the observer sends a short redstone pulse out of its back. Changes it notices include:

• A crop or plant growing a stage, or sugar cane and bamboo growing taller.
• A block being placed or broken.
• A furnace lighting up or going out.
• A door, trapdoor or fence gate opening or closing.
• Redstone dust or a lamp changing power.
• A note block being tuned, a composter filling up.

It doesn’t detect mobs or players moving in front of it, only block changes.

When you place an observer, the face points away from you and the red dot faces you. So look at the block you want to watch, and place the observer between you and that block.

Builds that use observers

Crop farms. The best-known use. An observer watching sugar cane, bamboo, pumpkins or melons fires a piston the moment the crop grows, breaking it off for hoppers to collect. The designs on our automatic farm guide nearly all start this way.

Clocks. Two observers facing each other trigger each other forever, giving a very fast pulse. That’s useful for item elevators made of droppers.

Flying machines. Observers notice when a slime block moves and fire the next piston. That’s the engine behind piston “vehicles” like the one in our moving car guide.

Block update detection. Point an observer at a door or trapdoor and it tells a circuit whenever someone opens it, which is handy for alarms.

Edition differences

Java and Bedrock observers don’t detect exactly the same set of updates, and their timing differs a little. A farm built from a Java tutorial can fail in Bedrock. Use designs made for your edition, and read redstone basics if you want to understand why a circuit isn’t firing.