Miniature remade of the "Mengenlehreuhr" found in Berlin with part available in my apartment

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This is project with was on my list for future projects for quite some I decided to start with it. In short: The goal is to make a miniature remake of the Mengenlehreuhr found in Berlin by Willy Pragher (CC BY 3.01) found on Wikimedia

More Information about the original can be found on Wikipedia. Of course my Version is planed to have a  more bookshelf compatible size.


  • first Version Assembled
    • ALL leds working
    • stls available on github
  • Demo code running
    • Demo code available on github
    • Time encoding in firmware working
    • RTC implementation pending



  • Ardruino Nano (the classic one to fit in Case)
  • DS3231 RTC Module
  • red and yellow 3mm LEDs
  • some wires

3D printed parts:

colors of choice (recommendation in brackets)

  • 1x Base with pole (black/grey)
  • 1x top frame  (grey)
  • 6x big round digit. Must be semi transparent (4x red + 2x yellow)
  • 6x big digit. Must be semi transparent (4x red + 2x yellow)
  • 2x small round digit . Must be semi transparent (2x yellow)
  • 9x small digit . Must be semi transparent (3x red + 6x yellow)
  • 1x big round top digit. Must be semi transparent (yellow)

Hot glue to stick it all together

  • Early test on Video

    Alex06/21/2020 at 17:04 0 comments

    First test of the LEDs in Video

  • New Pole Version

    Alex05/25/2020 at 21:37 0 comments

    The new Version of the Pole now includes an enclosure for the electronics. The bottom will be left open. for easy design and also to access the battery. There is a hole for the USB connector of the Arduino Nano for Power.

  • Selecting Electronics and test pole

    Alex05/25/2020 at 21:30 0 comments

    As Electronics for this Project I selected an Arduino Nano clone and a DS3231 RTC module. Quite handy to have box full of modules at hand.

    I also reprinted the front grey frame part. I am much more satisfied with this now. The surface finish is better. I just changed the Filament - no extra rework. Here you can see the new frame with the test pole. The finale version of the pole will include a box for the electronics an the base.

    Also need to finish the wiring of the LED which is only ~80% made in this picture

  • First print an LED test

    Alex05/03/2020 at 19:16 0 comments

    Did a first Print. I am not 100% satisfied with the outcome of the grey frame. I will try using different printings settings or a different filament.

    The LEDs are 3mm THT Leds which get pushed from the back inside the transparent red and yellow parts. For quick testing I just put two LEDs in. They are powered by a coin cell.

  • First 3D Design

    Alex05/03/2020 at 00:20 0 comments

    Most of the Body will be 3D-Printed. In this 3D printed Top 3mm LEDs will be mounted from the back. The red and yellow parts will be printed with transparent filaments. This is a first screen shot from Fusion360:

    Later I will add a pole and some kind of base. Inside the Base O will also place most of the Electronics. So far I think I will use a Arduino Nano and a RTC module.

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Dan Maloney wrote 05/04/2020 at 20:15 point

I had never heard of that clock before. I always like unusual display like that. Nice job!

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davedarko wrote 05/06/2020 at 08:45 point

Alex was the one who told me about it, and I live in Berlin :D

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j wrote 05/03/2020 at 19:43 point

Not untill now. I found it, but let me comment in it a bit and i'll get back to you.

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Ken Yap wrote 05/03/2020 at 08:55 point

Nice. This one would be more ambitious:

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Alex wrote 05/03/2020 at 19:24 point

Also nice. If you scale that down this reminds me to Microfluidics

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j wrote 05/03/2020 at 08:35 point

I love this clock! If you need code for that i could help out.
Neopixels were in use here:

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Alex wrote 05/03/2020 at 19:26 point

Nice. Did you published that code somewhere? I will use normal single color LEDs.

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