The Detector - Train is a block from the Railcraft mod. This block is meant to output a Redstone signal based on the type of Minecart that passes in front of it. The Detector - Train will output a Redstone signal if the amount of linked carts in front of it matches the amount specified in the GUI. It can have a minimum of one linked cart, and a maximum of 100 linked carts. They can be placed under or beside Minecart Tracks, and will output a signal to the side that has a small square. When a Redstone signal is active this square will turn red.