Scrap Mechanic Logic Gates — Wiring, Timers, Repeaters & Automation
How logic gates work in Scrap Mechanic: AND/OR/NOT/XOR wiring, sensors, timers and repeaters — build automatic doors, traps and factory logic.
Scrap Mechanic Logic Gates — Wiring, Timers, Repeaters & Automation
Logic gates turn Scrap Mechanic from a building game into an engineering game. With AND/OR/NOT/XOR gates, sensors, timers and repeaters you can automate doors, farms, traps and entire factory lines. This guide covers the gate set, basic wiring, and the timer/repeater patterns that most automation depends on in Scrap Mechanic 1.0.
The Gate Set
| Gate | Behavior |
|---|---|
| AND | Output on only when all inputs are on |
| OR | Output on when any input is on |
| NOT | Inverts the input |
| XOR | Output on when exactly one input is on |
| Sensor | Output on when something enters its field — the automation trigger |
| Switch | Manual on/off |
| Timer | Delays or toggles on a schedule |
| Repeater | Re-transmits a signal, extends range or chains logic |
Power and signal wiring is drag-and-drop from the logic parts menu; every logic part has power/signal connectors that chain.
The First Build: Automatic Door
The canonical starter:
- A sensor on each side of the door
- Wire sensors into an OR gate
- Wire OR output into a piston or bearing that moves the door
- Power everything
Result: walk up, door opens; the OR gate means either sensor triggers it.
Timer Loops & The Repeater
Timers are the heartbeat of automation:
- Timer on delay — output fires N seconds after input
- Timer interval — pulses on/off on a fixed cycle (the "timer loop" every farm uses)
- Repeaters extend signal range — long factory runs need them every so many blocks, and they let you chain logic across a base
The classic auto-watering loop: interval timer → piston pump → water to crops → sensor confirms → timer resets. See the auto farm guide for the full build.
Creative mode has unlimited parts and no pressure — prototype every circuit there before committing survival resources. Skills transfer 1:1.
Traps & Defense Logic
Sensors + logic make static defenses automatic:
- Tripwire traps — sensor across a path wired to a spud gun or water cannon
- Turret logic — turrets gated by AND (sensor + switch) so you control when they fire
- Raid funnels — see raid defense for wiring multi-turret kill zones
Factory Automation
Combining gates scales to full production lines:
- Piston sorting — pistons push items along conveyors gated by sensors
- Craftbot triggering — craft orders triggered by inventory sensors
- Vault/security logic — switch-controlled locks
Piston & Electric Engine Notes
- Pistons are the motion workhorse — doors, presses, harvesters. Mounted pistons need clearance and consistent power
- The electric engine (1.0 addition) pairs with logic for quiet, on-demand machinery — no fuel, but needs charge management
Both get full treatment in the vehicle building and auto farm guides.
FAQ
Do I need logic gates for basic play? No — but they're required for advanced farms, traps and factories. Recipes unlock through the Farmers Hideout trader.
How do I power logic gates? Switches and stations supply power; some builds use engines or batteries. Creative mode needs no power.
What's the difference between a timer and repeater? A timer delays or cycles a signal on a schedule; a repeater re-transmits an existing signal to extend range or chain logic.
Can logic gates build a calculator? Yes — the community has built working calculators, elevators and even music players out of logic gates.
Related Guides
- Auto Farm Guide — Fully Automated Farming
- Raid Defense — Automated Defenses
- Vehicle Building — Cars, Tanks & More
- Scrap Mechanic Guide — Complete Overview
Official resources: Steam store page · Official Scrap Mechanic Wiki — Survival Mode · Wikipedia · IGN game page
Last Updated: August 12, 2026