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.
Redstone Repeaters and Comparators Explained
A repeater boosts a redstone signal back to full strength 15, delays it by 1 to 4 redstone ticks (0.1 to 0.4 seconds) and only lets it go one way. A comparator keeps, compares or subtracts signal strengths, and reads how full a chest, hopper or other block is. Both face the way the arrow on top points.
How do you craft them?
| Component | Recipe |
|---|---|
| Redstone repeater | 3 stone + 2 redstone torches + 1 redstone dust |
| Redstone comparator | 3 stone + 3 redstone torches + 1 nether quartz |
Nether quartz is mined in the Nether; see the Nether.
What can a repeater do?
- Repeat: redstone dust fades by 1 per block and dies after 15; a repeater sends it out at 15 again.
- Delay: right-click to set 1, 2, 3 or 4 redstone ticks; each tick is 0.1 seconds.
- Diode: signals only pass from back to front, so they cannot flow backwards into a circuit.
- Lock: a powered repeater or comparator pointing into its side freezes it in its current state, which is the base of memory circuits.
It can sit on full blocks, upside-down slabs and stairs, and glass; Bedrock also allows fences and walls.
What can a comparator do?
- Keep: with nothing at its sides it passes the rear signal on unchanged, 1 redstone tick later.
- Compare (front torch off): outputs the rear signal unless a side signal is stronger, then turns off.
- Subtract (right-click, front torch on): outputs the rear signal minus the strongest side signal.
- Measure: reads chests, hoppers, furnaces, barrels and other containers by how full they are, plus cauldrons, composters, cake, item frames, jukeboxes, lecterns, chiseled bookshelves and more.
What are they used for?
Repeaters build long wires, timers and the delay in a piston door. Comparators make item sorters, "chest full" lights and combination locks. A comparator next to a furnace can stop a farm when the output is full. Next steps: redstone clocks and item sorters.
Does redstone lag on ArtemisPvP?
Frequently asked questions
How much delay does a repeater add?
1 to 4 redstone ticks, which is 0.1 to 0.4 seconds.
How do you put a comparator in subtract mode?
Right-click it; the small front torch lights up.
Sources
Every fact on this page was checked against these pages; the wording is ours.