vacuum tube asics? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: September 03, 2018, 04:11:41 pm
content: Did this ever exist? Like someone putting a buncha vacuum tube guts together in one vacuum enclosure, rather then having a bunch of tubes in sockets?

author: rhb
author_rank: Super Contributor
timestamp: September 03, 2018, 04:27:12 pm
content: Multiple tubes in a single envelope were and still are common. Dual triodes were especially popular for push pull amplifiers because of the good matching. But they are more analogous to a transistor array than an ASIC.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 03, 2018, 04:30:22 pm
content: Yes, in the 1920s. Not that common to include passives as they need encapsulating to avoid outgassinghttp://electricstuff.co.uk/loewe.html

author: coppercone2
author_rank: Super Contributor
timestamp: September 03, 2018, 04:38:19 pm
content: Quote from: mikeselectricstuff on September 03, 2018, 04:30:22 pmYou can use glass dielectric or vacuum capacitors I think. I imagined resistors would be just wound on a ceramic bobbin without insulation, at least for low values. That would severely restrict your values though.I wonder if everything is exposed to the same atmosphere and contamination if some kind of contamination related drift parameter would happen to equalize rather then having everything in envelopes. It could be an opportunity to do some kind of cancellation.Or the contamination might severely degrade the non tube elements if it started to short out some mangenin. I wonder if you can build something fancy now adays with parameters that were considered irrelevant back then to meet some kind of unique specification.Interesting to think about the efficiency because the heater is typically isotropic so you can start to minimize power use.

author: David Hess
author_rank: Super Contributor
timestamp: September 03, 2018, 05:55:06 pm
content: Compactronsincluded more than the common two tube elements.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 03, 2018, 10:02:33 pm
content: There were a number of experiments along these lines. Some I read about in the 1970s were complete circuits on a hybrid substrate, with the whole substrate heated to enhance thermionic emission. I think I recall complexity levels measured in tens of gates. The purpose was circuits that would work in radiation environments and such. Haven't heard more about them since. Don't know if they didn't pan out or just disappeared behind a military secrecy veil. Or both.

author: coppercone2
author_rank: Super Contributor
timestamp: September 03, 2018, 10:09:23 pm
content: god damn that sounds cool you can get a missile through a nuclear barrage that way, or maybe fly next to certain stars.. or have a decent robot to fix shitty nuclear reactors.What is the method called?

author: David Hess
author_rank: Super Contributor
timestamp: September 03, 2018, 10:14:00 pm
content: Field emission devicesare an ongoing area of research but I do not know of any commercial applications.

author: coppercone2
author_rank: Super Contributor
timestamp: September 03, 2018, 10:14:59 pm
content: I read about that on slashdot before. He is talking about the same thing?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 04, 2018, 02:56:21 am
content: I can't really remember much more about the article. It was in some trade journal of the times. EDN or Electronic Design or some such. While they mentioned field emission cathodes the implication was that these were being operated very hot so simple thermionic emission was enough or nearly enough. They were using thick film resistors, fairly standard chip capacitors and such on a ceramic substrate, and as I recall the substrates were on the order of a dozen square centimeters. I kind of remember that two substrates were placed opposite of each other so for any one device the cathode was on one side and plate on the other. Vaguely reminiscent of cordwood packaging. Don't remember if they tried configurations more complex than diodes and triodes and don't know how the grid function was implemented in the triodes. I do recall that they were touting it as being particularly suited for space applications such as lunar bases due to the "free vacuum". I also recall that they had tested prototypes in a reactor core at impressive neutron fluxes, (and free heat from the location).This was about the time that silicon integration was really taking off and ways to rad harden transistorized devices were being developed. Having to give up microprocessor level circuit performance for additional rad hardness margin was probably just a non starter and this stuff died.

author: coppercone2
author_rank: Super Contributor
timestamp: September 04, 2018, 07:04:19 pm
content: Yea thats different then the nanoscale packaging, it sounds like some kind of microscale or miliscale technology. (yes, its a term, look up milifluidics, some people actually call it that, I had trouble finding a classifier between microfluidics and fluidics at first for something I was interested in.)It sounds like you might be kinda able to make this stuff, its more approachable then the thing david hess brought up. Sounds like a good backup circuit for your boron or whatever hardened processor for mission critical things, even if its simple, it sounds more reliable, or maybe for a power supply circuit or for a analog front end for a hardened MCU. It might end up lighter too.How were they heating it?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 04, 2018, 08:36:48 pm
content: As I remember they didn't have to do any auxillary heating on the one in the reactor core. Whatever reactor they used was hot enough. They mentioned simple solar heating for space applications. The only other application I recall mentioned, deepwell boring, also gets pretty hot naturally. There is always resistance heating as a backup.

author: David Hess
author_rank: Super Contributor
timestamp: September 04, 2018, 09:21:37 pm
content: The trade magazine articles I remember from that time involved field emission devices etched into silicon.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 04, 2018, 09:52:41 pm
content: Yeah, there was a lot of that. Aimed at flat panel displays as I recall.

author: David Hess
author_rank: Super Contributor
timestamp: September 04, 2018, 10:05:18 pm
content: It was for flat panels as well but what I remember is as a replacement for transistors in integrated circuits.

author: BrianHG
author_rank: Super Contributor
timestamp: September 04, 2018, 10:16:08 pm
content: Thanks to all those 'Vacuum tube dacs', I cannot find the true real Vacuum tube dac I once was told about which used multiple gate inputs with different mechanical structures inside the tube for each bit to mimic a real high voltage DAC. It was only 6 bits I believe. I tried to google for an image of the old soviet tech, but all I get are hundreds of digital dac boards with a vacuum tube pre-amp stage.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 04, 2018, 10:26:30 pm
content: There is all sorts of cool vacuum stuff to be found. A research computer at my University had implemented vacuum tube memory with each tube storing a kilobit of information in a package much smaller than the then current magnetic cores. It was a crt based dynamic memory concept with a rough 30 x 35 array of plates which were written and read by the scanning beam. I am sure the semiconductor dynamic ram inventors a few years later were aware of and influenced by the concept.

author: BrianHG
author_rank: Super Contributor
timestamp: September 05, 2018, 12:04:21 am
content: Found a vacuum tube ADC. Yes, it actually exists, a vacuum tube which converts analog to digital!See here:http://www.electricstuff.co.uk/glassadc.html

author: chris_leyson
author_rank: Super Contributor
timestamp: September 05, 2018, 12:49:20 am
content: @mikeselectricstuff wow that Loewe 3NF really is a work of art, absolutely beautiful demonstration of craftsmanship.Maybe one day when material science can make efficient electron emitters then traditional vacuum tube technology will come back into fashion. Field emission sort of works but relies on relatively high field strenghts, and because of the high field strengths the electron physics changes and you different structures to control the electron flow. So I don't see it happening any time soon.One advantage of vacuum tube amplifiers is a lack of reverse intermod products when compared to semiconductor amplifiers, you don't have the "varactor" effect and in some applications that matters. Co-sited transmitters are one example.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 05, 2018, 01:55:53 am
content: Yup, was gonna link to the glass ADC.Feast upon thishttps://www.radiomuseum.org/forum/usa_project_tinkertoy.html?language_id=5and THIShttps://en.wikipedia.org/wiki/Selectron_tube

author: Wolfgang
author_rank: Super Contributor
timestamp: September 05, 2018, 09:43:41 pm
content: What made this idea fail on a larger scale was the low MTBF.Even if all passives were encapsulated in glass, these multi-tubes contained a number of filaments.If just one of them broke, the whole tube became unusable.IIRC, they even tried to repair those in the beginning.In the analog TV era, some compound tubes were common (like two diodes and a triode in one glass, e.g. EABC80), but they had no other components inside.They were produces in vast amounts and cheap due to their simple internal structure, unlike the "tube ICs" with other components inside.

author: BrianHG
author_rank: Super Contributor
timestamp: September 05, 2018, 09:54:29 pm
content: How about this super high frequency tube:https://www.extremetech.com/extreme/185027-the-vacuum-tube-strikes-back-nasas-tiny-460ghz-vacuum-transistor-that-could-one-day-replace-silicon-fetsOk, it's not a real vacuum tube as it can be filled with helium, though still better in a vacuum and it can operate at room temperature without a heating element.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 05, 2018, 10:43:27 pm
content: Quote from: BrianHG on September 05, 2018, 09:54:29 pmThe vacuum tube never left!https://en.wikipedia.org/wiki/Backward-wave_oscillator

author: Beamin
author_rank: Super Contributor
timestamp: September 05, 2018, 11:16:38 pm
content: MrCarlsons lab did a video on a two vacuum tube AND gate or NOR gate where the tubes were in this dual holder thing with one vacuum tube pin out in the bottom. Was huge and the instructions made it sound like it was core i7: "What can it do? More like what can't you do with your vacuum tube gate!" If you think a four gate 14 DIP was big try doing that with four of these things.

author: Cerebus
author_rank: Super Contributor
timestamp: September 06, 2018, 02:19:47 am
content: Quote from: CatalinaWOW on September 04, 2018, 10:26:30 pmSeeWilliams Tube (aka Williams–Kilburn tube), used for the RAM of the Manchester Baby in 1948, storing 2K bits (64 x 32). They had an early version working in 1946. Magnetic core memory was first used in the MIT Whirlwind computer in 1951, which used a Williams Tube like device for an early version.The Williams Tube had the oddity that you could actually see the contents of memory just by looking at the CRT.