There is a long-standing tradition of graduates decorating the tops of their ceremonial caps. Most schools require that all the graduates wear identical gowns, so those cap decorations are often the only way for graduates to express themselves. Most people just use traditional fabric markers to write messages or glue small tchotchkes onto their caps, but some people like to put a bit more effort in. Mahdi Al-Husseini definitely fits into the latter group, because he adorned his graduation cap with this awesome internet-connected Nixie tube display.
Al-Husseini built a similar cap back in 2018 when he received his undergraduate degree in biomedical engineering from the Georgia Institute of Technology. That worked, but wasn’t as polished as he would have liked. So, in preparation for receiving his master’s degree in computer science from Georgia Tech this year, Al-Husseini completely redesigned the cap display. The new and improved cap features a display made from six Burroughs 5971 alphanumeric Nixie tubes. Six characters aren’t a whole lot to work with, but text scrolling is possible to display longer messages. The messages are shown in the beautiful glowing orange light that only Nixie tubes can produce.
The six Nixie tubes are controlled by a NodeMCU ESP32 board. Nixie tubes require a high voltage, so Al-Husseini included a power circuit on the cap to push the 200V needed to drive them. The original version of the cap created for his first graduation was powered by LiPo battery cells next to the Nixie tubes, but this version is instead powered by a battery bank stored in a pocket. The ESP32 board hosts its own web server to accept new messages and Al-Husseini developed a custom iOS app to connect to that server. All he has to do to change the message shown on the Nixie tubes is pull out his smartphone and enter some text in the app. Al-Husseini certainly isn’t the first person to think of adding an electronic display to a graduation cap, but his is definitely the most well-executed project of this kind that we have seen. In 2023, he will be receiving a second master’s degree and we can’t wait to see the cap he makes for that occasion.