In his incredibly detailed write-up over on Instructables, Jude Pullen created a very interactive way to search for Internet radio stations across the world by literally spinning it around. There is a simple base that displays a station, which is located directly below a stationary cursor.
The vast majority of this project is constructed from 3D-printed pieces — 22 to be exact, so plenty of filament is needed. A soldering iron is used to assemble the electronics, which includes an LCD, several buttons, a couple of rotary encoders, and a Raspberry Pi 4 B. An ample number of screws are also used to hold the whole thing together while a user spins the globe.
As previously stated, there are 22 STL files that need to be printed for this project, and they can be found at step six of the tutorial. Pullen used an Ender 3 with a 1mm nozzle and 1.75mm PLA filament. CURA was the slicer of choice, and it seems to have worked quite well. After each part had been printed, he cleaned them up and placed brass inserts for each screw to fit into.
The globe for the project is a kid's 20cm that can be had for a mere $10, and the write-up mentions that it is important to ensure each half lines up fairly well, or else the program will be unable to get a solid location match. The top of the globe got removed and bored out to make room for a 12mm coupling. This then gets attached to the top of the cradle, allowing it to spin freely along the Z-axis.
In order to track where the globe is positioned, a pair of rotary encodes are attached — one per axis. An RGB LED and several buttons were then soldered to their own perfboard pieces, along with an I2C-enabled 20 x 4 LCD. Although there was a custom PCB designed for this project, Pullen mentions that a regular Raspberry Pi Proto Shield HAT will suffice, as seen below.
The most difficult part of this project to create was the software, as it has to keep track of the globe's position, find where the nearest station is, and then show relevant information about it. The program starts by calibrating the globe's location to a known point and then continuously checks if the encoders have moved. If they have, their position is mapped to a new pair of coordinates, which then causes a new radio station lookup. If several stations are found in the same area, such as Los Angeles or London, then the dial on the front of the base can be used to cycle through the various options.
All in all, the RadioGlobe project is an amazing showcase of ingenuity and coming up with a new way to do a dull task.