Physicist Mortiz v. Sivers has put together an unusual display which combines the concept of a sand art table with electro-magnetism — and that can serve as a clock when you tire of doodling magnetic art.
"In my search for unique display ideas I came up with this concept," Sivers explains. "It can be described as the fully magnetic equivalent of a kinetic sand art table. Below a magnetic field viewing film a small magnet is moved in 2D by PCB coils. In this way the magnet can draw patterns on the film like the ball bearing does on sand. The display can be used to draw patterns but because I am a big fan of unique clocks I also programmed it so that it can display the time."
The heart of the project is a clever custom PCB design which turns the surface of the board into a stepper motor, allowing magnets to be moved in two dimensions under electronic control. Printed on a flexible substrate, this board is positioned below a layer of magnetic viewing film — and controlled from a Wemos D1 Mini ESP8266 microcontroller.
In order to draw to the display, a stepper motor controller shifts a physical magnet — measuring just 2mm on a side and 1mm in height — underneath the magnetic viewing paper. As the magnet moves, it shifts the magnetic fields — which are then made visible to the naked eye on the viewing film.
If this sounds familiar, it should: moving a single magnet beneath specially-sensitized magnetic viewing film is exactly how the classic children's toy Etch A Sketch works. In Sivers' case, though, there's no knobs or XY gantry mechanism to be seen: the magnet moves entirely based on the PCB beneath it, without a traditional motor mechanism involved anywhere. Sadly, wiping the display isn't quite as easy as shaking an Etch A Sketch — requiring the magnet to make a completely clean sweep of the display before drawing the next image.
This isn't Sivers' first use of magnetism as the driving force behind a display. Earlier this year he released the Magnet Viewing Clock, which used numbers cut from magnetic foil rotating behind magnetic viewing film to tell the time. Last year, his focus was more on heat as a display system — using thermochromic panels and custom PCBs to show the time based on shifting temperatures. We've also seen the same magnetic-PCB-motor trick before, too, including in a project by Kevin Lynagh and a smart magnetic speedway from Jeff McBride.
Sivers has published an Instructable for those wanting to learn more, with design files, source code, and 3D-printable STL files for a case available on GitHub under an unspecified open source license.