Minecraft wiki entry for Telegraph, associated text: All telegraphs, no matter how basic or complex they are, require four things: a sending device, an inverter, redstone wire, and a receiving device. The sender will just about always be in the form of a lever. Anything else, such as a button or pressure plate, cannot be easily used to create a message, as they will remain activated for at least 0.9 seconds. A lever, on the other hand, can be shut off as soon as the player wants to, allowing for the quick pulses needed for telegraph languages such as Morse code. After the sender comes the inverter, a simple logic gate that inverts its input to create the output. For instance, if the input wire is powered, the output wire will be off. These are almost always used in telegraphs because redstone torches (a common type of receiver) create their own power. This means that without an inverter, the torch will turn off when a pulse is sent. Although this is only an issue of appearance, it may lead to confusion during interpretation of the message, which is tricky enough by itself. Then comes the all-important wire, which allows you to send your message as far as you want (although the longer the wire, the more likely it is that something goes wrong). The wire consists of redstone wire, and, depending on its length, redstone repeaters placed on every fifteenth block. This will stretch out for as long as needed, until it reaches its destination; the receiver. Receivers can be anything from a redstone torch that blinks when a single pulse is received to a room filled with redstone repeaters, displaying the entire message before the player.