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Echo Telegraph
Building: Intermediate
Program: Advanced

Building Instructions







Echo Telegraph Programming

Use the Rhythm_Echo program for the Echo Telegraph.  This program uses the File Access block to store the rhythm timing numbers in a data file, and then reads back the numbers so that it can copy your rhythm.

When the program displays "Ready", tap out any rhythm on the telegraph lever.  You can also hold down the lever to get longer tones.  When you leave the button alone for 2 seconds, the program will think the rhythm is done, and then it will play it back for you.


  • Real telegraphs didn't generate sound tones with a speaker but actually moved the lever down with a magnet to force a mechanical tap sound when you were listening to a message.  Can you extend this design to add a motor to move the lever down in sync with the tones?

  • For a programming challenge, Try modifying the Rhythm_Echo program to use the NXT sound sensor instead of the touch sensor, then see if you can make a program that will echo a rhythm that is "spoken" to the NXT through the sound sensor.

  • Real telegraphs were usually used to transmit messages coded in Morse Code.  As an advanced programming exercise, can you extend the Rhythm_Echo program to recognize letters of the alphabet in Morse Code and display them after playing them back?

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