Printer and Telegraph Machine




A telegraph machine and printer built using the Mindstorms EV3 kit (31313).

It manipulates a pen to draw text on a sheet of paper. You can control what text is printed by tapping out Morse Code on the touch sensor.

You can find more detailed information on wiring, calibrating and operating this robot, along with the building instructions, at
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Name Printer and Telegraph Machine
Designer JKBrickworks
Designed 2017
Inventory 336
Theme Mindstorms > EV3
Alternate Build of 31313-1 Mindstorms EV3
Star Wars™ Imperial Star Destroyer™


  • 1 month, 3 weeks ago [email protected] (40)
    Hi Jason, my printer do not properly print letters can you pease tell me why it doesn't. I folllowed the instuctuons and built it. I love all your build and this one mainly thanks for all of this.
  • 2 months ago ImLoriro (370)
    Hi Jason,  the printer is awesome, but i have a small problem: the printer in the first PrintTestPage program prints correctly, but in the second one the right part of the paper remains white: the pen does not touch the paper, but at left yes. What can i do? Thanks a lot for your help! Loriro
    • 2 months ago JKBrickworks (22K) MOC Designer
      No idea why it would work correctly once and then not the second time. Maybe something got loose, or the pen shifted slightly?
      • 2 months ago ImLoriro (370)
        I dont know the reason, but for me the printer is not correctly horizontal.. if the problem continues I will rebuild the involved parts.

        Thanks a lot for your help. I will check and try again...
  • 12 months ago DylanDoesStuff (40)
    I love all your builds and decided to build this one. I spent a good hour or two making this exactly how instructions say, downloaded the program, ran calibration, and got it to print. I printed the test page and my own message and both the letters came out backwards. I would really like to get this to work, so if you know what the problem is, can you please tell me? I was thinking of adding an extra gear to the large motor that runs the pen to reverse it, but decided to put a hold to it. Also, what size paper do you use? I had to cut 8.5 by 11 to get the right size. Thanks!
    • 11 months, 4 weeks ago JKBrickworks (22K) MOC Designer
      So it still prints the letters from left to right and from top to bottom, but they individually come out backwards? I haven't heard of this problem yet, so I don't know off the top of my head what might be happening. I use an 8.5x11 sheet of paper cut in half.
      • 11 months, 2 weeks ago Hris (52)
        Hi Jason,
        I had the same problem but I found how to fix it please see my comment below if somebody asks how to fix the same problem.
    • 11 months, 2 weeks ago Hris (52)
      I had the same problem but I fixed it by switching the motor that controls the paper feed (motor B). The motor was pointing the wrong way and turning the wheels the wrong way as well. Placing it correctly fixed the problem. Please check that you have placed it correctly. Hope that helps!
  • 1 year, 2 months ago Sachro (756) MOC Designer
    your lego builds are Amazing how do you do it!
  • 1 year, 5 months ago MoiBananas (123)
    This build is insane! How did you figure out how to translate the dots and dashes into English text?
    • 1 year, 4 months ago JKBrickworks (22K) MOC Designer
      Thanks! Essentially, I just start a timer every time the touch sensor changes state. Then, when it changes state again, I see how much time has elapsed. Based on that, I build up an array of dots/dashes until the pause is long enough to indicated a character has been encoded. I then convert that dot/dash array into a binary value and look up the corresponding character in a lookup table.

      Conceptually the logic for Morse Code is very simple (by design). Of course, programming it in the EV3 graphical environment is a whole other matter, and turns it into a bit of a complicated mess. :)
  • 2 years ago LegoBrick480 (32K)
    Interesting design, pretty smart. You're a good Lego builder
  • 2 years, 1 month ago kenay (1)
    amazing build! you must be an engineer.
  • 2 years, 3 months ago msx (14K) Blogger
    This is so great! And you used only parts from the official set?? You rock!
  • 2 years, 3 months ago willison_r3 (5K)
    Whenever a newsletter with the title "New MOC by JKBrickworks" arrives I get excited. This time again I am really stunned about your newest creation. What a surprising and clever idea!

    Thank you for all your creations and inspirations on what is possible with Lego bricks!
  • 2 years, 3 months ago TimM75 (6K) PRO
    New tech for old tech... Ingenous! My late grandfather would appreciate this build, he was HAM radio operator and loved old radio technology, he had several working telegraphs. 

    Lego, has to be one of most versatile building toys in the world.
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Submitted by ImLoriro Aug. 19, 2019