There’s a long history of devices originally used for communication being made into computers, with relay switching circuits, vacuum tubes, and transistors being some well-known examples. In a smaller way, pneumatic tubes likewise deserve a place on the list; [soiboi soft], for example, has used pneumatic systems to build actuators, logic systems, and displays, including this latching seven-segment display.
Each segment in the display is made of a cavity behind a silicone sheet; when a vacuum is applied, the front sheet is pulled into the cavity. A vacuum-controlled switch (much like a transistor, as we’ve covered before) connects to the cavity, so that each segment can be latched open or closed. Each segment has two control lines: one to pressurize or depressurize the cavity, and one to control the switch. The overall display has four seven-segment digits, with seven common data lines and four control lines, one for each digit.
The display is built in five layers: the front display membrane, a frame to clamp this in place, the chamber bodies, the membrane which forms the switches, and the control channels. The membranes were cast in silicone using 3D-printed molds, and the other parts were 3D-printed on a glass build plate to get a sufficiently smooth, leak-free surface. As it was, the display used a truly intimidating number of fasteners to ensure airtight connections between the different layers. [soiboi soft] used the display for a clock, so it sits at the front of a 3D-printed enclosure containing an Arduino, a small vacuum pump, and solenoid valves.
This capacity for latching and switching, combined with pneumatic actuators, raises the interesting possibility of purely air-powered robots. It’s even possible to 3D-print pneumatic channels by using a custom nozzle.
Thanks to [Norbert Mezei] for the tip!
Where did the post about a mercury Rover go?
This Mercury rover post?
https://hackaday.com/2026/04/10/a-mercury-rover-could-explore-the-planet-by-sticking-to-the-terminator/
It’s still there, but maybe got lost “below the fold” when you looked: There’s a glitch (at least on my Win10/Firefox setup) where the last article on the first page gets lost in limbo when it gets bumped to the second page by a new article.
The bumped article doesn’t appear at the top of the list of posts on the second page, but is still accessible by the previous/next article buttons at the bottom of the next/previous articles.
It reappears at the top of the second page when another new article gets posted.
I’ve been hoping they fix the broken comment system or add an edit button before I bug them about this bug :-)
That could explain why quite often i discover an old article i had not seen when i was browsing through older articles pages the day before! But it is with Firefox/macOS, so the bug is maybe not browser/OS dependant.
And talking about bugs, i can no more subscribe to “Email me new comments” since i would say 2 or 3 years maybe. Well: i can, but i’m no more receiving any emails. But i still can access the management page from one of the older mail i received in the past. And i also still receive emails when somebody add a reply to a very old post! Go figure…
Yeah, that one too.
I can’t complain too much though — I’m getting more than I pay for.
It would be great if hackaday would support date/by_day pagination.
HaD orders by date, and you can easily navigate manually. E.g.: https://hackaday.com/2026/04/01/ But, yeah, there’s no nice forward/back by day navigation. Maybe you can write a browser plugin or greasemonkey script for that.
I’d appreciate a “sort by newest comment” option, so I don’t miss updates on old articles when I happen to miss the comment in the “recent comments” section
In theory, perhaps given a larger cell or a stiffer membrane, you should be able to use the vacuum within a cell to control a pneumatic transistor and with a read enable logic section, read off stored bits.
It would be interesting to see something like a pneumatic version of Conway’s game of life.
this makes me incredibly uncomfortable
Oh! Then you would love some David Cronenberg films.
Using this and his transistor, maybe he can create a calculator called the Vacuumulator. :)
Use vacuum tubes to control vacuum display! Early computers used vacuum tubes, might as well come in a full circle!
A true resurgence of vacuum-state technology!
Now, might this be useful for a 3D printing plate, mold, etc.
Pop objects right off to roll onto a conveyor belt…
Quite a neat display, but I was still a bit disappointed when I saw the solenoids at 12:11. Somehow I expected that all the logic (counters, display decoders) was implemented with vacuum valves too. (Not the light bulb variant!)
Simple logic (and and or gates) are fairly common in pneumatics but because of their bulk and cost (compared to a PLC) it’s usually only used for very simple functions.
I do wonder if this can be miniaturized enough to be used as a practical braille display.
It looks steam-punk-ish to me.
Nice.
A new color theme could further help with that.
A material that changes color when stretched would also be nice.
Now that’s interesting… What if the silicone sheet was translucent white and the bottom of the cavity was a bright color? Or maybe even just black? Would help visibility quite a bit, I imagine.
Good concept to build a Braille display.
It could be interesting for young children.
The stretchy rubber membrane could also be used as a user input device.
I do wonder how small the vacuum pixels could be made.
Pneumatic “electronics” reminded me of an April Fools’ article about pneumatic computers in Datamation back in the 1970s. An unsuccessful search for the article online brought up more serious articles, including a 1962 book, “Computers– The Machines We Think With”, by D.S. Halacy, Jr.
The short last section in Chapter 3, “Another Kind of Computer”, discusses pneumatic computers and, more briefly, fluid computers. The author describes pneumatic equivalents of diodes, capacitors, inductors, and flip-flops. One paragraph lists research facilities conducting research into pneumatic computers:
“A good question at this point is just why computer designers are even considering pneumatic methods when electronic computers are doing such a fine job. There are several reasons that prompt groups like the Kearfott Division of General Precision Inc., AiResearch, IBM’s Swiss Laboratory, and the Army’s Diamond Ordnance Fuze Laboratory to develop the air-powered computers. One of these is radiation susceptibility. Diodes and transistors have an Achilles heel in that they cannot take much radiation. Thus in military applications, and in space work, electronic computers may be incapable of proper operation under exposure to fallout or cosmic rays. A pneumatic computer does not have this handicap.”
Here’s the book (skips down to Chapter 4 of the book; scroll up 10 or so paragraphs to see the last section of a very long Chapter 3):
https://www.gutenberg.org/dirs/7/2/5/7/72572-h/72572-h.htm#Page_72
These things existed. In quantity, even. A pre-electronic-age automatic transmission is essentially a hydraulic computer taking inputs from torque, pressures and rpm, and controlling output valves and brake bands to select a gear ratio. Prior to the electronification of all things, all that sophistication was in a closed box that required no electrical input whatsover. And it still performed at over 90% efficiency.
Gotta say, though, the Toyota E-CVT is a pretty darned cool modern turn on it.
It’s a fantastic display! But is anyone else slightly disappointed that he wasn’t able to make the whole thing without a microcontroller running it? Or am I a bit too early and this level of technology hasn’t been invented yet?
I have this vague memory of my dad giving me a catalogue for somebody’s pneumatic traffic light logic systems, where the “relays” (or other logic gates) had magnets in them to keep its current state, even if the power (and thus pressure) goes out. And no, I haven’t figured out whose it was yet.