REDSTONEPEDIA › Circuits › Pulse shapers
One pulse when switched off (falling-edge detector)
2-tick pulse · 2 blocks
When the input turns off, the output gives one short pulse of 2 ticks (0.1 s); turning the input on does nothing.
starts after 4 ticks (0.2 s) · needs an input of at least 6 ticks (0.3 s) · made of observer, sticky piston · fits in 1×1×3
23 versions, 1 to 256 ticks
Every size 23
The best design for each size: pick one to see it.
| size | blocks | numbers |
|---|---|---|
| 1 tick (0.05 s) | 4 blocks | starts after 2 ticks (0.1 s) · needs an input of at least 2 ticks (0.1 s) |
| 2 ticks (0.1 s) (this page) | 2 blocks | starts after 4 ticks (0.2 s) · needs an input of at least 6 ticks (0.3 s) |
| 4 ticks (0.2 s) | 4 blocks | starts after 8 ticks (0.4 s) · needs an input of at least 6 ticks (0.3 s) |
| 6 ticks (0.3 s) | 4 blocks | starts after 10 ticks (0.5 s) · needs an input of at least 6 ticks (0.3 s) |
| 8 ticks (0.4 s) | 4 blocks | starts after 12 ticks (0.6 s) · needs an input of at least 6 ticks (0.3 s) |
| 10 ticks (0.5 s) | 5 blocks | starts after 1 tick (0.05 s) · needs an input of at least 2 ticks (0.1 s) |
| 12 ticks (0.6 s) | 16 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 14 ticks (0.7 s) | 16 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 16 ticks (0.8 s) | 13 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 18 ticks (0.9 s) | 16 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 20 ticks (1 s) | 20 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 22 ticks (1.1 s) | 20 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 24 ticks (1.2 s) | 13 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 26 ticks (1.3 s) | 20 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 28 ticks (1.4 s) | 20 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 30 ticks (1.5 s) | 20 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 32 ticks (1.6 s) | 13 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 36 ticks (1.8 s) | 24 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 38 ticks (1.9 s) | 24 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 40 ticks (2 s) | 13 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 64 ticks (3.2 s) | 13 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 128 ticks (6.4 s) | 13 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
| 256 ticks (12.8 s) | 13 blocks | starts after 6 ticks (0.3 s) · needs an input of at least 6 ticks (0.3 s) |
Try it
Hold IN under the view for a long press, tap it for a short one: the box marked OUT turns red while the output is on. Press play under the view to watch a demo on a loop; touch any other control to take over.
How this design does it: The smallest falling-edge detector, 2 blocks: the input pushes an observer away with a sticky piston, and when the input turns off the piston pulls it back, where the observer fires once into the cell under it (the output, a 2-tick pulse); pushed away, it fires beside the output.
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.
Blocks used: observer sticky piston
Details: how it works, measurements and properties
In depth
When the input turns off, the output gives one short pulse of L = 2 ticks (0.1 s), starting 4 ticks (0.2 s) after the input turned off. When the input turns on, nothing happens. It handles every input pulse of 6 ticks (0.3 s) or longer.
Use it to react to something stopping, e.g. a lever being switched back.
How to try it
Press play under the view to watch the demo on a loop (the badge reads demo with the step it is on; the same sequence is drawn as a timing diagram below). Touch any control to stop it and try the circuit yourself.
To try it: press and hold the IN button of the bar (or the cell tagged IN) to power that input; a quick tap sends a short 2-tick pulse.
Inputs are tagged in lime; the output is tagged OUT: the redstone lamp in that cell (the view adds it to show the output) lights while the output is on (the output strip by the demo badge shows its last 40 game ticks, 2 seconds). Drag to look around, pinch or scroll to zoom, step one game tick at a time with the step button.
Inputs and output over time
The input follows this schedule (the 3D view's demo plays the same). Lime: an input is on; orange: the output is on (taller = a stronger signal, 1 to 15). Time runs left to right in game ticks (20 ticks = 1 s).
Swipe the diagram sideways: the whole sequence lasts 425 ticks (21.25 s).
Step by step (11 lines)
in 2 ticks (0.1 s): no output <- not handled in 3 ticks (0.15 s): +7 for 2 in 4 ticks (0.2 s): no output <- not handled in 5 ticks (0.25 s): no output <- not handled in 6 ticks (0.3 s): +10 for 2 in 8 ticks (0.4 s): +12 for 2 in 10 ticks (0.5 s): +14 for 2 in 15 ticks (0.75 s): +19 for 2 in 20 ticks (1 s): +24 for 2 in 30 ticks (1.5 s): +34 for 2 in 40 ticks (2 s): +44 for 2
Measurements
| metric | value | what it means |
|---|---|---|
| L | 2 ticks (0.1 s) | the length of the output pulse |
| delay | 4 ticks (0.2 s) | the time from the input's edge to the start of the output pulse |
| min-pulse | 6 ticks (0.3 s) | the shortest input pulse handled correctly (every longer one works too) |
| tileable | every 2 (2 0 0) |
Notes from its designer
The smallest falling-edge detector, 2 blocks: the input pushes an observer away with a sticky piston, and when the input turns off the piston pulls it back, where the observer fires once into the cell under it (the output, a 2-tick pulse); pushed away, it fires beside the output. Copies stand side by side every 2 blocks. Detail: inputs of 6 ticks or more (a shorter one pulls the observer back before it has fired).
Properties
| Study | Pulse shapers |
|---|---|
| Kind | One pulse when switched off (falling-edge detector) |
| Blocks placed | 2 (not counting the input levers or buttons and the lamp the view adds) |
| Box | 1×1×3 (3 blocks of space) |
| Made of (the blocks that change state) | observer, sticky piston |
| Inputs / outputs | IN (repeater) / OUT |
| Flags | several versions of one mechanism |
| Design file | pulse-fall-piston-observer-L2 |
The design file
Design file (14 lines)
# One pulse when switched off: 2-tick pulse · 2 blocks # https://vjeux.github.io/redstonepedia/circuits/pulse/pulse-fall-piston-observer-L2.html name: pulse-fall-piston-observer-L2 circuit: falling-edge tile: 2 0 0 port input: 0 1 0 port output: 0 -1 1 origin: 0 0 0 palette: O minecraft:observer[facing=up,powered=false] S minecraft:sticky_piston[extended=false,facing=south] layer 0: S O