Detector Rail
minecraft:detector_railA detector rail is a redstone component that doubles as a track for minecarts. When a minecart rolls over it, the rail becomes powered and emits a redstone signal to adjacent dust, repeaters, comparators, and mechanisms. A comparator facing away from the rail can even read the fullness of a passing minecart with a chest or hopper.
FAQ
How do you craft a detector rail?
Combine 6 iron ingots, 1 redstone dust, and 1 stone pressure plate on a crafting table to produce 6 detector rails per craft.
What does a detector rail actually detect?
It senses any minecart passing over it and emits a redstone signal for about the same duration as it takes the minecart to cross.
Can a detector rail tell how full a minecart is?
Yes. A redstone comparator facing away from the detector rail outputs a signal strength proportional to the fullness of a minecart with a chest or hopper riding it.
Do all mobs avoid walking on detector rails?
No. Spiders, cave spiders, and wardens can walk across detector rails normally, while most other mobs treat them like an obstacle.