Add the Cutest Little Etch sAo Sketch Onto Your Con Badge

Conference “badges” have become community favorites over the last decade or so, and now they can be pretty dang elaborate. Each year, attendees of the Hackaday Supercon receive a really nifty badge and all of the recent designs have included an SAO connection for adding modules. Those add-ons have become just as elaborate as the badges, as demonstrated by Andy Geppert’s Etch sAo Sketch.

The SAO standard, which originally stood for “Shitty Add-On” and has since been rebranded as “Simple Add-On,” allows for power transfer and communication between badges and add-on modules. You might, for example, design an SAO module to give badges LoRa hardware so you can send messages to your friends at the conference. But makers tend to have eclectic interests and good senses of humor, so we end up with all kinds of oddball SAOs that are anything but practical. The Etch sAo Sketch certainly checks those boxes and it is a real delight.

This is a digital recreation of the classic drawing toy, with a cute little 128×128 grayscale OLED screen. Two potentiometers give the user control over the X and Y axes. There is also a three-axis accelerometer, which could enable some interesting new user input options.

As with many SAOs, the Etch sAo Sketch omits any kind of enclosure and instead relies on the red PCB with white silkscreen. While that PCB is fairly simple (the real Etch A Sketch has a pretty minimalist design), Geppert did come up with one very clever trick: screen-locating spheres.

When attaching displays to PCBs, it can be hard to get the alignment perfect and so you often end up with uneven borders or, even worse, portions of the screen being covered up. Screws work for alignment, but then you have to put holes in your PCB. Geppert’s brilliant solution was to use tiny copper balls surface-mount-soldered onto pads. It is pretty easy to center those on the pads, and vias would make it even easier. The display PCB’s mounting holes mate with the spheres and, voila, you have a perfectly aligned screen! You can even solder plated mounting holes onto the spheres to give the display a mechanical anchor.

This is already awesome, but Geppert plans to have an improved prototype e-ink screen-based version ready to show off at Supercon 2024, which is happening next weekend.