Check Out This 7-Segment Display That Runs on Air

An LCD may be the go-to display choice for most makers building a DIY electronic device these days, but this is hardly the only option. If you are going for a different look, you can go with a more traditional option like an E Ink screen, or something completely off the wall like this flip sequins display. Or, you could try an air-powered seven-segment display, like the one just created by YouTuber soiboi soft.

On first inspection, the device looks like a minimalist four-digit clock housed in a frosted enclosure. But beneath that clean exterior lies something far more unusual: a fully functional, air-driven computing system that behaves like random access memory — except instead of electrons, it uses vacuum pressure and flexible silicone membranes to store data.

The build relies on high-precision 3D-printed components, including a perfectly flat main body that ensures airtight seals. A bright orange display membrane forms the visible segments, which are pulled inward by a vacuum to represent digits. Once actuated, these segments remain in place, physically holding their state even after the vacuum is removed.

Each segment effectively acts as a memory cell. The mechanism that drives them is a pneumatic analogue to a transistor: a tiny valve where a membrane blocks or permits airflow depending on control pressure. When activated, a vacuum forms and pulls the membrane inward. When the valve closes, the trapped vacuum keeps the segment latched — creating a persistent bit of information.

To control the system, a microcontroller drives an array of 11 solenoid valves. Seven of these correspond to the standard segments of a digit, forming a shared data bus across all four digits. The remaining four act as write-enable lines, selecting which digit should receive the current data. This architecture mirrors conventional RAM design, where data lines and address lines work together to store values in specific locations.

Writing a number involves setting the desired segment pattern on the data lines, then briefly opening the write-enable valve for a chosen digit. The corresponding pneumatic “transistors” open, vacuum flows in, and the digit updates. Once the valve closes, the digit retains its shape — no continuous power required.

While the device operates much slower than electronic counterparts — refreshing roughly one digit per second — it remains practical for applications like clocks and timers. It also offers a tangible demonstration of computation. Instead of invisible electrical states, this “visible RAM” lets users watch data being stored and held in real time through physical motion.

To learn more about this unique seven-segment display, be sure to check out the project video below.