Minecraft wiki entry for Telegraph, associated text: As indicated by the name, messages created in a one-way telegraph may only be sent in one direction, greatly limiting its capabilities. The schematic shown demonstrates a short configuration, complete with the required sender (1), inverter (2), wiring (3) and receiver (4). However, it is the only kind of telegraph with any real practicality in single player. If one were to have the sender in a mine, and the receiver in their house, they could effectively use it like a post-it stamp, leaving a message in their house to remind them, for example, that there was diamond in that mine. Expanding on this idea, they could have a series of redstone torches in their home indicating which of their mines had diamond or some other valuable element. Whenever another mine was discovered to have this element, they could simply flip a switch, and the mine's corresponding torch would activate in the house. An example of this is shown on the left. Another use would be as a simple distress signal in multiplayer, as it is always an issue of having to simultaneously type your call for help and run away from whatever is troubling you.