A Mechanical 7-Segment Display PCB
Inspired by Carl Bugeja's work, this display uses seven coils and H-bridge drivers on a PCB to actuate each section.
Last year, IndoorGeek came up with a mechanical seven-segment display, which pushed physical sections in and out using electromagnets. It’s a clever setup, but creating coils for each one can get a bit tedious, and takes up a lot of room. But for his latest iteration, he’s designed the actuating coils into a PCB, inspired by Carl Bugeja’s FlexAR work.
Rather than drawing coils from scratch, he’s employing a Python script to generate short segments that wrap around and around on the board, propelling the on-segment magnets forward and backward. This action is handled by seven DRV8837 H-bridge drivers, acting in a similar manner to if they were controlling a series of motors. Permanent Neodymium magnets are embedded in the segments themselves, which are 3D-printed along with the frame.
More details on the build, including parts used, Arduino code, and STLs are available here. A summary is seen in the video below, and additional info on making these PCB-based coils can be found in the second clip.
Future plans include modifying the PCB design to make it smaller, improving the 3D-printed parts, and, of course, making a few more of these devices. Perhaps there’s a four-digit seven-segment clock in IndoorGeek’s future, clicking away to show the time?