Though it seems like a shame, Nixie tubes, which use a series of cathodes inside a low pressure gas filled tube to display numbers, are no longer produced or in common use. Though many of us don’t have a great idea of what these tubes look like in person, they can be seen to emit a nice warm glow in images, and have a 3D effect because of the cathode arrangement.
Though interesting, these display devices have a number of disadvantages over LEDs and the like. These include the fact that they are (or were) comparatively difficult to manufacture, and the fact that they need an electrical potential of well over 100 volts to operate.
Because these devices are both rare, difficult to work with, yet oh-so-cool, hackers have come up with a few solutions that combine modern electronics with some of the more interesting features of this technology.
Examples of what people have come up with include an edge-lit tube seen on Hackaday in 2012; LIXIE, which uses the same sort of “light pipe” edge-lighting concept; and the Nixie Pipe, which again uses the same basic idea, but has functionality built-in that links several of these number displays together.
Naturally, multiple digits can be used to form one of the most popular modern uses for Nixie tubes, a clock! Now you can have a clock with the depth of a Nixie tube display without fooling with expensive vintage components that are quickly turning into unobtainium, or the complications of high-voltage electronics!