As researcher and engineer Nicolas Kruse puts it, “Electromagnetic displays are nice. They have a very high contrast, even in bright sunlight. Not to forget the beautiful clicking sound when they change state.” He also notes that power consumption can also be quite low if they don’t change state much, making them ideal for many situations. Unfortunately, these displays aren’t common today, making them difficult to obtain, and usually rather expensive.
Naturally, this makes this type of display method a great candidate for 3D printing, and Kruse has come up with a single-digit 7-segment prototype that looks (and sounds) pretty darn good. In his setup, each 3D-printed segment contains a small neodymium disk magnet, allowing each one to be flipped by a coil wrapped around a 1 mm iron core. Everything is controlled by a custom PCB, based on an ATtiny44 chip, along with a trio of 74LS138D modules and associated components.
STL files, including circuit diagram and source code needed to build the device, can be downloaded via Kruse’s write-up. For a preview of what you’d be constructing — of if you’d just like to hear and see its sweet clicking action — feast your senses on the short demo clip below!