Updated 23 October 2026. Facts on this page come from minecraft.wiki, minecraft.net and the live Artemis PvP server; sources are listed at the bottom.
Pistons, Observers and Hoppers Explained
A piston pushes up to 12 blocks when powered, an observer sends a short redstone pulse when the block in front of it changes, and a hopper moves items at 2.5 a second and stops when powered. Together they run almost every automatic farm: the observer sees a crop grow, the piston breaks it, and hoppers collect the drops.
How does a piston work?
A piston faces toward you when placed. When it gets a redstone signal its head extends, taking 2 game ticks (0.1 seconds), and pushes up to 12 blocks; when the signal stops it retracts. A sticky piston also pulls the block in front of it back. Slime blocks and honey blocks drag the blocks touching them along, which is how flying machines and block movers work. Some blocks cannot be pushed at all, including obsidian, crying obsidian, bedrock, beacons, ender chests, enchanting tables, spawners and portals.
How does an observer work?
The observer's face (with the eyes) points away from you when placed, and its output (the red dot) toward you. When the block in front of its face changes, such as a crop growing or a block being placed or broken, it emits a signal strength 15 pulse for 2 game ticks. Two observers facing each other make a fast observer clock. Observers also pulse after being moved by a piston, which drives flying machines. On Bedrock an observer reacts to any block update; on Java to shape updates such as state changes.
How does a hopper work?
A hopper has 5 slots. Each cycle it first pushes items out through its spout (down or sideways), then pulls from a container above it, or picks up items lying on top of it. After moving items it waits 8 game ticks, a rate of 2.5 items a second. A redstone signal locks a hopper so it stops moving items, and a comparator reads how full it is. Chains of hoppers are called hopper pipes. Mine a hopper with a pickaxe or it drops only its contents.
How do you use them in a farm?
- Observer + piston: the observer watches a crop such as sugar cane and fires the piston when it grows; see sugar cane farms.
- Hoppers under the farm collect the drops into a chest; hopper minecarts can collect them too.
- See redstone basics and crop farming for more.
Does ArtemisPvP have its own farming blocks?
Frequently asked questions
How many blocks can a piston push?
Up to 12.
How fast does a hopper move items?
2.5 items per second: one transfer every 8 game ticks.
Sources
Every fact on this page was checked against these pages; the wording is ours.