Updated 25 October 2026. Facts on this page come from minecraft.wiki, minecraft.net and the live Artemis PvP server; sources are listed at the bottom.
Observer in Minecraft: How It Works and Uses
An observer watches the block in front of it, the side with the face, and gives a short redstone pulse out of its back whenever that block changes: a crop growing, a block placed or broken, a door opening. It is the key part of automatic farms and flying machines.
How do you craft a observer?
6 cobblestone, 2 redstone dust and 1 Nether quartz. It detects block updates such as growth stages, state changes and placements, then sends a short pulse (2 game ticks, 0.1 seconds) from the back. Pistons can move observers, which makes them the heart of flying machines.
What is it used for?
- Sugar cane, bamboo and melon farms that harvest when a crop grows
- Flying machines with slime blocks
- Detecting doors, rails or note blocks changing
- Pulse makers in compact circuits
More: flying machines.
More about the observer
Observers notice changes in the block they face, not mobs walking past. Two observers facing each other make a very fast clock. They are cheap once you have Nether quartz, and they are smaller than most older detector circuits.
Where does it fit in redstone?
Redstone parts fall into power sources (levers, buttons, plates, torches, observers), wiring (dust, repeaters, comparators) and mechanisms (pistons, dispensers, droppers, hoppers, lamps and doors). Most circuits combine one of each: something to detect, something to carry the signal, and something to act. Signals move along dust at once, while each torch, repeater or comparator adds a small delay measured in redstone ticks of 0.1 seconds. Start with redstone basics.
Tips
Place it facing the crop or block you want to watch; the red dot on the back lights up when it fires. Signal strength: signal strength.
Frequently asked questions
What does an observer detect?
Changes to the block it faces.
Sources
Every fact on this page was checked against these pages; the wording is ours.