Alarm Lamp
alaindustrial:reactor_alarm_lamp
Summary
The Alarm Lamp is a red beacon in an iron cage. Two things light it, and either one is enough:
- The reactor it is pressed to. A lamp placed with its base on the shell of a formed reactor room — on the roof, on a wall from the outside or from the inside — or on the controller or a rack of a bare reactor, becomes part of that reactor and lights on its own by the reactor's alarm: no dust, no antenna. You can put up as many lamps as you like (owner's decision, 2026-11-04).
- Redstone, anywhere. From the reactor antenna's boom over any circuit of yours — dust, repeaters, an inverter — at the other end of the base, by your bed, at the entrance; and just as well from a pressure plate by a door or a mob farm: the lamp does not care where the signal came from.
It goes on any of the six faces: base against the block you place it on, cage pointing away from it.
The lamp makes no sound (the alarm sound belongs to the future reactor siren, and does not tell signal strengths apart: any signal above zero lights it, and from its reactor it is lit from the warning all the way up to the emergency.
What it does
| Property | Value |
|---|---|
| Input | a redstone signal of any strength from any side (as with a vanilla redstone lamp) or the alarm of the reactor its base is pressed to |
| Lit | light 14 (as bright as a torch), the lens is red and flashes |
| Signal removed | goes dark after 4 ticks (as a vanilla lamp does) — a short pulse is not cut off mid-flash |
| Tells 7 from 15 | no — on/off; a comparator or the length of the dust tells the level (see "Telling a warning from an emergency") |
| Sound | none |
| BlockEntity | none |
| Tie to a reactor | only through its base: pressed to the shell of a formed room, a controller or a bare reactor's rack — lit by that reactor's alarm; placed anywhere else — by redstone only |
A lamp on a reactor
| Property | Value |
|---|---|
| Where | base on any cell of the shell of a formed room (outside or inside), on the controller, on a bare reactor's rack |
| Lit | while the alarm is 7 or higher: the same latches as the antenna boom — on at 70 %, off below 60 %; lit through a meltdown (85 ↔ 70 %) and the countdown |
| Normally | dark |
| How many | as many as you like |
| How it is found | the controller collects such lamps on its walk of the shell (every 40 ticks), for a bare reactor around the controller and the racks; a lamp put up by hand lights from the next walk |
| Who writes it | the controller, as the last step of its tick, and only on a change — no extra updates |
| When it goes dark by itself | a lamp lit by its reactor checks its support every 20 ticks: if that cell is no longer a formed room's shell, a controller or a rack — it goes dark |
A reactor with an antenna and dust and a lamp pressed to the reactor are two independent paths: the lamp still works from redstone, and it is lit while at least one of them is on.
A known caveat: a controller destroyed by an explosion (rather than by a player) leaves the shell "formed" until the next build — the same cosmetic loose end as the shell's seamless texture — and a lamp on such a shell may stay lit. A player who breaks the controller takes the room apart, and the lamps go dark.
Telling a warning from an emergency
The antenna boom gives 7 on a warning and 15 in an emergency (see the antenna). The lamp lights on either of them, and a circuit tells them apart:
- Dust length. The signal drops by 1 for every block of dust. A lamp more than 7 blocks of dust away from the boom only gets a signal from 15 — so it lights only in an emergency; a nearer one lights already on the warning.
- A comparator in subtract or compare mode separates 7 from 15 just like any other signal.
A home-made emergency stop
The controller runs while a signal reaches it. Lead the alarm signal through an inverter (a redstone torch) to the controller, and the reactor stops itself on an alarm. Without the inverter the alarm signal would do the opposite and start the reactor — which is why the boom's tooltip and the guide book say so plainly. The boom itself never touches the controller and never feeds it a signal (see the antenna).
Light and flashing
- The light of a lit lamp is a steady 14, as bright as a torch (owner's decision, 2026-11-04). Only the picture flashes: the block's light does not jump, or the world would recalculate its lighting on every flash.
- The flashing is an animated lens texture (
.mcmeta): a running highlight no more than once a second, even, with no random drop-outs (the same rule as for the tablet screen in. - The lens is drawn with
light_emission: 15in the model, so the flash reads in complete darkness. - The animation runs on the atlas's shared clock: every lamp in the world flashes in sync. That is expected — vanilla animated blocks flash the same way.
- A lamp that is off has a dark red lens with no glow and looks exactly like a lamp with no signal.
Energy
| Field | Value |
|---|---|
| Role | none |
| Buffer (EU/FE) | 0 |
| Max in / out (EU/FE/tick) | n/a |
The lamp uses no EU/FE: it is powered by the redstone signal itself, as a vanilla lamp is, or by its reactor's alarm. An alarm should not depend on whether a cable has been run to the lamp.
Block properties
| Field | Value |
|---|---|
| Shape | almost a full cube: 14 × 15 × 14 px, base flush against its support (standing on the floor: x and z 1..15, y 0..15), turned to the face; the cage is see-through ⇒; the six shapes are built once (ADR-023) |
| Collision | matches the shape |
| Placement | on any of the 6 faces (facing = the clicked face): base against the support, cage outward; on a side it points away from the wall |
| Support | not needed to stay up: removing the support does not drop the lamp; for the tie to a reactor the support is what its base is pressed to |
| Hardness | 1.5 |
| Blast resistance | 6.0 |
| Tool | pickaxe (required for the drop), tag mineable/pickaxe |
| Sound | metal |
| Light emission | 14 while lit or alarm, 0 otherwise |
| Block states | facing (6) × lit (2, from redstone) × alarm (2, from the reactor = 24 |
| Drop | the lamp itself, ×1 |
The lamp is a metal light fitting, not a wall block of the reactor: it needs none of the shell's toughness. It does not take a place in the room's wall and does not count as a breach — it is pressed to the shell from the outside or the inside.
Appearance
The look is variant 01 "Beacon in a cage", chosen by the owner on 2026-11-03 out of three sketches (tools/model_sources/reactor_alarm_lamp_concepts/, source v01_cage_beacon/reactor_alarm_lamp.bbmodel): a red glass lens in an iron cage on a dark base, with a cap on top.
- Two models: off (a dark red lens) and on (a lens with the animated texture and
light_emission: 15), turned by the block state to each of the six faces, like a vanilla end rod. - The item icon is the off model.
- The cage does not hide its neighbours: the block is not an occluder, so neighbouring faces are drawn.
Recipes
- Crafting — "3×3" shape, ×1 per craft.
I G I I = iron ingot ×4
G L G G = red stained glass pane (minecraft:red_stained_glass_pane) ×3
I R I L = redstone lamp (minecraft:redstone_lamp) ×1
R = redstone ×1It reads like the device itself: a vanilla lamp in an iron housing behind red glass, plus a wire. The recipe is not tied to the nuclear stage — the lamp suits any circuit and is available right away.
Progression
- Tier: none (a passive block, no EU/FE).
- Requires: vanilla materials only.
- Unlocks: nothing new; a companion to the redstone output of the reactor antenna.
Related
- Reactor Antenna — its boom gives the redstone alarm signal.
- Reactor Controller — where the alarm comes from; it runs on a signal.
- Reactor Lamp — another light: a shell block, lit while
formed.
Crafting
Shaped Crafting
red st
red st
redsto
red st
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Alarm Lamp