REDSTONEPEDIA › Circuits › Block change detectors (BUD switches)

Block change detectors (BUD switches)

Notice a change you cannot otherwise see: a crop or a tree that has grown, a block placed or mined, to start a harvester or an alarm.

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The pictures show each design with its inputs and a lamp on its output; the block counts leave those out.

Block change detector (players call it a BUD)

Fires its output when the block at its target cell is placed, removed or changed, without any redstone signal reaching it.

notices blocks placed, removed, changed, updatedBlock change detector

notices blocks placed, removed, changed, updated · 3 blocks

notices a pure block update and resets itself; the simpler 2-block BUD switch (a sticky piston and a redstone block) latches until you reset it; for visible block changes a single observer is enough · reacts in 3 ticks (0.15 s) · 1 tick (0.05 s) output pulses · ready again after 6 ticks (0.3 s) · made of redstone block, slime block, sticky piston · fits in 1×4×1

tiles every 2 blocks1 block wide