Minecraft wiki entry for Train_station, associated text: When you put your money in it goes inside the hopper. This makes the comparator go one more block which powers the rest of circuit. You need an AND gate and a clock to make a pulse. The pulse makes the dropper lose one thing so it reverts to its one block. This makes it resettable. It will power the dropper to give you a ticket. If you have any wrong ones it will not go in the hopper and disappear after a while. Make the money from the first dropper go into lava or into a hopper chain to a chest. This is quite advanced so only attempt if good with redstone.