Buddy Block

As the name suggests, the Buddy Block is a BUD (block update detector). It reacts to changes in neighboring blocks and outputs a short redstone pulse to a single side (determined during placement) when they occur. Buddy has a wide range of uses including everything from detecting events such as doors being opened, to detecting the various growth stages of plants, to aiding in counting the number of Turntable rotations that have occurred when automating the production of Pottery. Note that Buddy will NOT react to changes in redstone elements (redstone dust, repeaters, and redstone torches) to help prevent creating feedback loops as Buddy powers these same elements on and off.

Crafting

Stone	Redstone Eye	Stone	File:CraftBuddyBlock.png
Redstone Eye	Redstone Dust	Redstone Eye
Stone	Redstone Eye	Stone