High-Tech LEGO Projects

4

Morse code transmitters

In the 19th century, people used Morse code to transmit messages by telegraph, a device that creates an audible tone in a receiver. To send a message in Morse code, you encode letters and numbers by using a combination of short tones (called dots) and long tones (called dashes). Numbers are composed of five tones, and letters are composed of no more than four tones. Figure 4-1 lists the codes for every letter and number.

While telegraphy has long passed from daily communications, people still use Morse code in certain emergencies or on occasions when sophisticated communication technology fails. To send a Morse code message, a person can blink a flashlight, raise flags in either hand, or tap on pipes. Famously, Jeremiah ...