Gregory's Serverthis is a Nuvistor! it's a super-advanced vacuum tube that could have beaten the transistor.
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RCA developed all new equipment to make it. this machine seals a batch of Nuvistors automatically! so how did they miniaturize the Nuvistor? time to cut one in half. check out the cross section! i'd annotate my photo, but RCA published a really nice cutaway diagram, so i will show you that instead. Nuvistors found their way into some high end applications but transistors surpassed them in a few years, and they just faded away. fascinating to imagine an alternate reality where transistors never worked and people figured out how to miniaturize vacuum tubes, etching arrays of them on metal wafers and building computers. In fact, they could even have built the entire Internet using a series of tubes. @jonhendry not that i am aware of. i vaguely recall someone made a tube with passive parts like resistors inside, but no other semiconductors. @tubetime @jonhendry I think I have one with a diode inside, at least that's what it looks like, it might be something else entirely.  @tubetime @jonhendry the Korg/Noritake Itron Nutube assemblies might combine the two: https://www.korgnutube.com/en - it's basically using a VFD as an audio amplifier @tubetime What #AdobeFirefly thinks it would look like. #GenerativeAI Prompt: long shot of thousands 1 millimeter tall nuvistors lying on huge printed circuit boards. With industry starting to look at analog computing again, the tube might yet make a comeback. They're so good for analog circuits.  @tubetime I do remember that year or so when SEDs were going to be the hot new display technology and we were all going to get separate CRTs for all of our subpixels   @tubetime that was actually part of the background of the scifi table top role playing game GURPS Lensman.  @tubetime the Vacuum Transistor allows fabrication of chip-scale vacuum tubes on normal CMOS process. These devices switch in the terrahertz range and require neither a heated filament nor a vacuum, since the source-to-drain distance is shorter than the mean free path (which means electrons won't hit any other atoms along the way): https://spectrum.ieee.org/introducing-the-vacuum-transistor-a-device-made-of-nothing  @tubetime There is progress on the latter, sort of: https://spectrum.ieee.org/introducing-the-vacuum-transistor-a-device-made-of-nothing @tubetime Neat! Figured tubes kept the same form factor. Er, up until https://www.sweetwater.com/store/detail/VX50BA--vox-vx50ba-50-watt-bass-combo-amp and https://www.korgnutube.com/en , much more recently. And curious for your thoughts on those. In my science-fiction universe, I call this technology "electron plumbing". (While semiconductors did come to be there, electron plumbing still owns the high-power applications.) @tubetime reminds me of the Robert Symons quote in this piece on cold-cathode traveling wave tubes: https://spectrum.ieee.org/the-quest-for-the-ultimate-vacuum-tube#toggle-gdpr @tubetime Very cool. This is textbook Christensen Innovator's Dilemma case study. I had no idea.  @tubetime oh that's hella cute. I always used to think Nuvistors were external plate tubes, but it looks like the metal shell is floating and can be grounded on this one. Otherwise, the construction style used inside the Nuvistor is identical to that used in large RF power tubes... just... unembiggened.  Is that anything near a TO-5 package? I worked for Teledyne Relays and we had DPDT 1A relays in a TO-5 can. Still seriously small! That's a lot of little widgets that I imagine are desired to be concentric.... 
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  @tubetime The lovely HP 3400a RMS voltmeter (1964) uses one of these in the input amplifier!   |
in 1959, RCA took their tube-making expertise and made this micro miniature tube almost as small as a 1950s transistor