And you thought reading an analog watch was tough…
The Mengenlehreuhr, which in German means “Set Theory Clock,” is also known simply as the Berlin Clock. It is the first clock in the world to tell time via illuminated colored sections, and was initially installed in 1975. It keeps time in a 24-hour format, with four rows of LEDs, representing hours on the top two rows, and minutes on the two rows below that, and a blinking second “hand” on top. 40 years later, and we have the technology to replicate this clock at home using readily available and inexpensive technology.
Maker “mr_fid” decided to do just that using an Arduino Nano (ATmega328), a real-time clock (RTC) unit and three eight-bit shift registers. These shift registers combined give 24 individual outputs, equalling the number of lighting sections in the original clock.
As the hours, minutes, and seconds don’t really match up with our base 10 numbering system, or even a computer’s binary system, programming isn’t as straightforward as some projects featured here. He includes an explanation, as well as the code he used, in his linked Instructables article.
‘Fid doesn’t go into all of the mechanical details of his build, preferring to let his drawings and photos do most of the talking. One interesting feature to note is his use of frosted acrylic material on top of the LEDs. Using a material like this can help soften LED or other lights to make illumination more even. This diffusion effect that can be used for artistic purposes as seen here, or for more practical reasons like lighting in a computer vision system.
Intrigued? You can head over to the project’s page here.