Glorious, and absurd… I’m saying that as a compliment. Eric Schlaepfer, who posts as TubeTimeUS, built a 555 timer out of eight tetrode nuvistors, and Hackaday covered it this month.
It descends from his own discrete transistor 555 kit, per the repo, so it’s the same circuit rebuilt around tubes. Every tube needs a heater to make the cathode emissive, which cost the board extra pins and about 7.5 watts. Eight tubes, so by my math that is roughly 0.94 watts per tube before the board has counted a single pulse. A 555 in a plastic package wouldn’t dream of it.
The mechanical detail I like best: the nuvistor has its plate on a cap at the top, so the footprint calls for Mill-Max sockets and, I’m not making this up, a standard 1/4″ fuse holder to clip onto that top connection. Somebody’s parts drawer got a promotion. Hackaday notes nuvistors shrug off electrostatic discharge and electromagnetic interference better than modern transistors, which sounds like a reason invented after the fact, and I’ll take it anyway.
Can you build one? Partly. The repo has the KiCad schematic, a PDF and the custom footprint, but not the board layout, because that comes from the kit. I’d also like the tube types and the timing accuracy on the page. I’d build it anyway, and eat the 7.5 watts.