Editing 40d:Repeater

{{quality|Exceptional|21:04, 26 April 2011 (UTC)}}{{av}}
In Dwarf Fortress<sup>1</sup>, a '''repeater''' is a device which creates a never-ending cyclic on/off signal. Several designs are possible, and they can be made to operate at varying rates.  They (usually) use fluid or creatures to trigger pressure plates to create a cycle, continually trigger the plates, which can then also be linked to automatically and ceaselessly trigger external systems.

Fluid uses the natural flow and varying depths to trigger plates.  Creatures use [[path|pathing]], opening and closing doors to attract the creature to step on the plates.

As a general warning, always have a way to turn off the repeater, and/or allow your dwarves later access for repairs or modifications.

[1] Everywhere else, a "repeater" is a signal retransmitter, and an "oscillator" or "clock generator" is what this article describes.

===Fluid repeater===

One example [[fluid logic]] repeater (described on the [http://www.bay12forums.com/smf/index.php?topic=33563. forum] by [http://www.bay12forums.com/smf/index.php?action=profile;u=16168 AncientEnemy]) is as follows:

 ≈≈≈≈≈ - river or brook
 ═╗≈╔═ - wall to channel out after construction
  ╠F╣  - shutoff floodgate ''(linked to exterior lever)''
  ║#║  - 1-tile drawbridge (linked to pressure plate)
  ║p┼  - pressure plate (set to 7-7 water), and access door
  ╠F╣  - floodgate (linked to pressure plate)
  ╚═╝

This repeater toggles fairly slowly, about once every 300 steps, making it suitable for operating [[bridge|bridges]], [[floodgate|floodgates]], and [[Trap#Upright Spear/Spike|upright spikes]]. As an added bonus, the bottom wall (immediately beyond the floodgate) can be removed and connected to a cistern whose water level will be automatically maintained at a level between 3 and 4 deep.

===Goblin repeater===

This is not as regular a repeater, but just as reliable in the long run.

A goblin or creature is placed (via [[Activity_zone#Pit.2FPond|pitting]]) in a loosely circular hall with one [[door]] and one [[bridge#Drawbridges|drawbridge]] leading to a single path out. Beyond these is the bait - an exit, a [[restrain|restrained]] animal, or just your fortress in general - something the creature wants<sup>1</sup>.  One path is open, and the goblin heads that way to kill the animal. A pressure plate is stepped on, which shuts one path and opens the other<sup>2</sup> (and triggers an exterior system).  The goblin reconsiders his path, and heads back around for the other hallway - where the process is repeated.

# For instance, if using a [[rhesus macaque]], some item of value would suffice to attract the creature.
# Doors and drawbridges open alternately when connected to a [[trigger]].

                A               A = bait animal (or similar)
  ╔════════════╝  ╚═══════════╗
  ║           ┼║   ┼          ║   ┼ = access (bridge or door), currently open 
  ║  ╔═════════════════════╗  ║   ┼║= access, currently shut 
  ║  ║                     ║  ║  
  ║  ╚═════════════════════╝  ║   P = pressure plate
  ║     g ->    P             ║   g = goblin, w/ current path
  ╚═══════════════════════════╝

The only caveat is to make sure there is enough room between the pressure plate and door/bridge, to give them time to shut well before the goblin gets there.  Additional mechanized doors or a cage trap may be desired if you ever wish to "turn off" the repeater without killing the goblin/creature (by safely isolating it).

===Pump-based repeater===

This repeater will send regular signals at a frequency determined by the speed of [[pressure plate]] recovery. Basic design consists of 4 [[screw pump]]s and 4 [[pressure plate]]s but other versions are possible, depending on the number of separate steps you need.

[http://www.bay12games.com/forum/index.php?topic=34407.msg572324#msg572324 Forum thread] with description and explanations.

[http://mkv25.net/dfma/movie-1370-pump-basedautorepeater DFMA movie] showing a pump-based repeater in action.

See also: [[User:MrFake/NStepCyclicRepeater]]

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{{Raw Tile|÷|#0f0|#000}}{{Raw Tile|÷|#008000|#000}} is a screw pump which pumps from the light side to the dark side. {{Raw Tile|^|#f00|#000}} is a pressure plate which disengages gear {{Raw Tile|☼|#f00|#000}} when water of depth 1-7 lands on it. The red, green, blue, and yellow pressure plates and gears are color coded only to show which is linked to which. In the game they'll all look like {{Raw Tile|^|#f0f|#000}} and {{Raw Tile|☼|#c0c0c0|#000}}. Building a pump after the gear which powers it or a gear after the pressure plate which disengages it will introduce a 1-step delay; so, depending on build order, the repeater might have a period between 400 and 408 steps. If the pumps, gears, and pressure plates are built in that order, then this system will repeat every 400 steps, exactly. Start the repeater by using a pond zone to dump 2 buckets of water onto any one of the plates.

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