Copper Bulb — Minecraft block

Overview

The copper bulb, added in 1.21, is a light source with a toggle built into it, and it behaves differently from every other redstone-driven lamp in the game. A redstone lamp follows its signal: powered means lit, unpowered means dark. A copper bulb latches instead — each redstone pulse flips it between on and off, and it stays in that state after the signal goes away. In other words it is a T flip-flop in a single block, and that saves the four or five components a redstone builder would otherwise need to build one, which is why it turned up in so many circuits within days of release. Its second quirk is oxidation. Like every copper block it ages through exposed, weathered and oxidized, and its light level drops with each stage: 15 when fresh, then 12, then 8, then 5 at fully oxidized. So the block is both a lamp and a dimmer, controlled by how long you leave it out in the world, and honeycomb waxes it at whichever brightness you want. A comparator reads whether a bulb is lit, which makes it a usable one-bit memory readout.

Toggle lighting that stays on after the button is released, a single-block T flip-flop for redstone circuits, and dimmable decorative lighting tuned by oxidation stage.

Minecraft classifies Copper Bulb as a building block. Copper Bulb has a crafting recipe, so it is renewable as long as you can source its ingredients. At a hardness of 3 it takes a moment to break but never slows a build down.

It needs at least a stone pickaxe to drop anything; a weaker tool destroys it for nothing. Mining it returns the block itself, so it is safe to relocate. A full stack holds 64.

It is crafted from Block of Copper, Blaze Rod, and Redstone Dust. It goes into exactly one recipe: Waxed Copper Bulb.

About the copper set

How to get it

Craft 4 bulbs from 3 copper blocks, 1 blaze rod and 1 redstone dust. The blaze rod means a nether fortress trip, but 1 rod makes 4 bulbs, so the recipe is cheap in practice.

Tips

Each pulse flips it — use a button rather than a lever, or the lever's two edges will toggle it twice.
Light level falls from 15 to 12 to 8 to 5 as it oxidises, so wax it with honeycomb at the brightness you want.
A comparator beside a bulb reads its on/off state, which turns it into a readable memory cell.
It replaces a 5-component T flip-flop in most circuits, which makes compact door and lamp wiring much smaller.

Version notes

Copper bulbs were introduced in 1.21 (Tricky Trials) and are unchanged in 1.21.4.

How long it takes to break

Hardness 3 puts Copper Bulb at 15 seconds a block bare-handed, or 0.5 seconds with the right tool at netherite tier.

You are looking at 0.75 seconds on iron and 0.6 on diamond — the iron step is where the time actually falls.

A weaker tool still breaks it, but anything under stone returns nothing — you spend the time and lose the drop, which is how most veins get wasted.

Each Efficiency level adds level² + 1 to the tool's speed, so a level V tool clears this about 3.3 times faster than an unenchanted one.

* breaks the block but yields no drop
Tool	No enchantment	Efficiency III	Efficiency V
Hand *	15 s	15 s	15 s
Wooden *	7.5 s	1.3 s	0.55 s
Stone	1.2 s	0.35 s	0.15 s
Iron	0.75 s	0.3 s	0.15 s
Diamond	0.6 s	0.25 s	0.15 s
Netherite	0.5 s	0.25 s	0.15 s
Golden *	1.3 s	0.7 s	0.4 s

Properties

With 6 blast resistance Copper Bulb usually goes down to a nearby explosion. It is fully opaque and produces no light. A single slot takes 64, the usual full stack. The block is tagged for pickaxes, and only that class gets the speed bonus; everything else mines at bare-hand rate.

Transparent: No
Required tool: Stone Pickaxe