TNT duper (runs by itself)

drops each TNT straight down to explode at one point · 30 TNT a minute · 41 blocks

Lights 30 TNT a minute, and every TNT falls straight down and explodes at the same point under the machine, without ever using up its own TNT block.

no on/off switch, 13 blocks smaller than the main design · a push every 40 ticks (2 s) · first TNT after 21 ticks (1.05 s) · fits in 6×5×8 + 11 blocks of air under it

drops each TNT straight down to explode at one pointTNT duper3D view loading (or not available in this browser)

Try it

Press play under the view: it runs by itself: watch a lit TNT come out of the machine each cycle while its TNT block stays in place.

Build it

Download .litematic Download the design as text

The .litematic opens in Litematica (Minecraft 26.3): every block of the design in one region. The text file is the same build written as plain text, block by block.

Every TNT explodes 10 blocks under the machine, so stand it at least 11 blocks up for the blast to be in mid-air; the machine itself survives from 4 blocks up. Pour in the water where the view shows it.

Blocks used: dead tube coral fan iron trapdoor oak fence observer obsidian redstone block redstone lamp redstone torch redstone wire repeater slime block sticky piston stone tnt water

Details: how it works, measurements and properties

In depth

It keeps lighting TNT forever without using up its TNT block: 30 TNT a minute. Every 2 s a piston pushes the TNT block: a piston copies every block it moves before it clears the old cells, and a TNT that gets a block update while powered at that instant is lit where it stands (a primed TNT that falls and explodes 4 s, 4 s, later) while its moved copy lands as a TNT block again. Each push lights 1 TNT.

How to try it

The duper runs by itself as soon as it is built: press play under the view to watch it. Watch the piston push the TNT block every cycle and a lit TNT (flashing white) drop out of the machine each time, while the TNT block lands again in its place; a lit TNT vanishes when its fuse runs out instead of exploding. Pause and step one game tick at a time with the bar's buttons; drag to look around, pinch or scroll to zoom.

Measurements

metric	value	what it means
rate	30 TNT/min	lit TNT per minute
period	2 s	game ticks between two pushes (the engine's cycle)
per period	1	TNT lit by each push
latency	1.05 s	game ticks from the start to the first lit TNT
safe drop	4 blocks
stands	23 blocks above the ground (stand: in the design)

Properties

Study	TNT dupers
Kind	TNT duper (runs by itself)
Blocks placed	41
Box	6×5×8 (240 blocks of space)
Made of (the blocks that change state)	dead tube coral fan, iron trapdoor, observer, redstone block, redstone lamp, redstone torch, redstone wire, repeater, slime block, sticky piston, tnt, water
Inputs / outputs	none: it runs by itself
Flags	size
Design file	`tnt-precise-drop`

The design file

on GitHub

Design file (78 lines)

# TNT duper: drops each TNT straight down to explode at one point · 30 TNT a minute · 41 blocks
# https://vjeux.github.io/redstonepedia/circuits/tnt/tnt-precise-drop.html
# CIRCUIT: safe drop 4 blocks, in mid-air 10.0 blocks below the machine
name: tnt-precise-drop
circuit: tnt-duper
stand: 23
port start: 2 -1 3 last
origin: 2 0 -4
palette:
  A minecraft:oak_fence[east=true,north=false,south=false,waterlogged=false,west=false]
  B minecraft:observer[facing=down,powered=false]
  C minecraft:observer[facing=east,powered=false]
  D minecraft:dead_tube_coral_fan[waterlogged=false]
  E minecraft:observer[facing=north,powered=false]
  F minecraft:observer[facing=south,powered=false]
  G minecraft:observer[facing=up,powered=false]
  H minecraft:observer[facing=west,powered=false]
  I minecraft:iron_trapdoor[facing=north,half=top,open=false,powered=false,waterlogged=false]
  J minecraft:obsidian
  K minecraft:redstone_wall_torch[facing=east,lit=true]
  L minecraft:redstone_wire[east=none,north=none,power=0,south=none,west=none]
  M minecraft:repeater[delay=3,facing=west,locked=false,powered=false]
  N minecraft:repeater[delay=4,facing=south,locked=false,powered=false]
  O minecraft:oak_fence[east=false,north=false,south=false,waterlogged=false,west=false]
  P minecraft:sticky_piston[extended=false,facing=north]
  Q minecraft:stone
  R minecraft:redstone_block
  S minecraft:slime_block
  T minecraft:tnt[unstable=false]
  W minecraft:water[level=0]
  o minecraft:oak_fence[east=false,north=false,south=false,waterlogged=false,west=true]
  r minecraft:redstone_lamp[lit=false]
  s minecraft:sticky_piston[extended=false,facing=down]
layer -4:
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layer -2:
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layer -1:
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layer 0:
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