8 ms·

The Tube Computer

232 points by elvis70 2y ago

mikewarot 2y ago
Fuses help with the "bang", as do using 5U4 or other vacuum tube diodes in the power supply, which limit current. I've learned not to be absolutely frightened of B+ at 200-300 volts, though I definitely respect it. Once you get above 500 volts, and an amp... the danger is very real, and the fear returns, in spades.
- monocasa 2y ago
  That being said, the biasing voltages get crazy too, leading to the big boy voltages. 300v b+ combined with 200v c- means that you're at 500v of potential if you short the wrong bits that are probably right next to eachother.
  - peatandrepeat 2y ago
    Exactly why I keep wooden chopsticks in my amp repair kit. But the voltage is moot without the amperage to back it up, and most power transformers will happily supply it in heaps.
ownlife 2y ago
"The basic, domestic quality thermionic tubes have codes for a projected life span of either 1500 (6Н3П-Е) or only 500 hours (6Н3П). Many were used and then stored for over 50 years, quality stamps may have been accidentally altered, so life expectancy may be questionable, both for the tubes and for me!" I love the idea of an expiration date, or at least an ever-present need for repair. It emphasizes the idea that the computer is a machine, subject to the constraints of the physical world. There's something charming about that.
- fortran77 2y ago
  I restore a lot of 50s era tube radio equipment. The tubes are suprisingly robust! I'm surprised at how many times _resistors_ go bad, and of course we all know that capacitors fail. But more often than not, all the tubes in a typical 5 tube AM radio I find are working.
  - dhosek 2y ago
    Radio Shacks¹ used to have a tube tester machine in them.² I was always impressed that there was such a finite universe of tubes that a single machine could test all of them. ⸻ 1. For the kids, this was a store that sold various electric gizmos including radios and circuit components, then later computer and televisions. 2. I think they may have also been present in hardware stores as well.
    - euroderf 2y ago
      There was a tube tester in our town's main pharmacy. So in principle you could pull the main tubes from (say) your TV and have at it.
    - quercusa 2y ago
      There's a HeathKit one up on Ebay now: 'Heathkit TC-3 Tube Tester'
    - themadturk 2y ago
      I remember tube testers at grocery stores when I was a kid. I'd go with my dad to test tubes from our TV set, and buy replacements for burned out ones.
retrac 2y ago
Bit of an aside but I wonder how far tube technology might have advanced, without semiconductors intervening. In the late 1950s and early 1960s, GE, IBM, and RCA, probably other companies, were working on "integrated tubes" with many components in a single envelope, as well as techniques for easier and more automated manufacture. For example, introduced in 1959: https://upload.wikimedia.org/wikipedia/commons/b/ba/Nuvistor_530.jpg https://upload.wikimedia.org/wikipedia/commons/b/ba/Nuvistor...
- Animats 2y ago
  > Bit of an aside but I wonder how far tube technology might have advanced, without semiconductors intervening. There were Compactrons. There were subminiature vacuum tubes.[1] A one piece printed circuit board of glass, with multiple tubes, might be possible. A glass plate made with lots of recesses, electrodes and wiring created by photo-etching like printed circuit boards, a glass plate on top, pumped down to vacuum and sealed. A low-density integrated tube. That's what a plasma panel display is. It's an integrated array of neon lamps. In a vacuum fluorescent display, each illuminated element is a triode vacuum tube. So it's quite possible to fabricate a big array of tubes. Maybe something like a ball grid array would work for external connections. Probably could have been done if necessary. Density probably would have maxed out around the density of elements on on the most dense vacuum fluorescent displays. Maybe devices at 1mm scale, or 1,000,000 nm. Good enough for mainframes and minicomputers, but not microprocessors. [1] https://archive.org/details/The_MIT_Museum_The_Subminiature_Vacuum_Tube_The_Cycle_of_Technology https://archive.org/details/The_MIT_Museum_The_Subminiature_...
- adrianmonk 2y ago
  Would tube reliability have limited how much you could scale it up? As far as I know, tubes have a limited lifetime and burn out eventually. If you have a million or a billion of them, they might fail so fast that your computer simply doesn't work. I don't know whether reliability is a solvable problem. Tube-based devices were once very common, so that suggests it would have been solved if it could have been.
  - klodolph 2y ago
marcodiego 2y ago
For a long time I've been thinking about building one based on relays. The problem is that I would need a lot of relays just to achieve anything very simple. My solution: think about the simplest computer architecture I could come up with, and the simplest one was a NAND computer. In this architecture, the program is a simple loop with instructions all in the same format: input addess 1, input address 2, output address. The only supported instruction simply writes at the output address the result of a NAND operation of the input addresses. Since any circuit can be built using only NAND's, this computer can simulate any circuit, including the circuit of a Turing complete CPU. It certainly would be very slow, but relatively simple to build. I still have to think about a good type of memory for this machine. Maybe one day I'll take the courage to build it.
- fragmede 2y ago
  http://nandgame.com http://nandgame.com might help with that
- mrob 2y ago
  For something simpler than the computer described in the article, you might be interested in Usagi Electric's UE-1 vacuum tube computer. Construction is nearing completion, and it's documented on Youtube: https://www.youtube.com/playlist?list=PLnw98JPyObn0v-98gRV9PfzAQONTKxql3 https://www.youtube.com/playlist?list=PLnw98JPyObn0v-98gRV9P... This is a 1-bit design based on the Motorola MC14500B: https://en.wikipedia.org/wiki/Motorola_MC14500B https://en.wikipedia.org/wiki/Motorola_MC14500B Code executes directly from a literal loop of paper tape, so the clock speed is very slow. I expect this design would also work with relay logic.
  - anyfoo 2y ago
    Yes, code executes directly from a literal loop of paper tape, and more specifically, there is only one loop (the paper tape loop), and every instructions executes at every iteration. Yet it can do what any other computer can do (in terms of computation, not I/O), because not every instruction has to actually effectively do something in each iteration, and it is a cornerstone of theoretical computer science that you can transform every program into one represented in an academic language called "WHILE", which is restricted to exactly that principle: It only consists of a single outer WHILE loop, and then inside the loop you have a bunch of conditions.
Calimax 2y ago
[dead]
EMIRELADERO 2y ago
So, if this became sufficiently popular to a degree in which many more units like these were produced and released, and it was decided that they all should be connected somehow, in a sort of inter-network... ...it would finally be a series of tubes.
debo_ 2y ago
From the website: The person who built this appears to be (at least) 70 years old. Amazing! > My family was homeless when I was born. But my parents found work, the council found us a flat, and 20 years later my dad was the managing director of a very large engineering firm, and my parents built a fabulous home. > To cut a long story short, much later my parents had a few personal problems, and sadly my mum finally killed herself. I don’t think you ever get over it, you really just learn to live with it. > My life then went a bit pear shaped. I trusted bad people and guess what, really bad things happened. Very kind friends managed to put me back on my feet, and then, at 55, I met Judy and her family, and we’ve had the most wonderful 15 years together. > So please, what ever happens, please don’t give up.
lalabert 2y ago
“So please, what ever happens, please don’t give up.” Love that - thank you!
lalabert 2y ago
Tommy Flowers (https://en.wikipedia.org/wiki/Tommy_Flowers https://en.wikipedia.org/wiki/Tommy_Flowers) knew a thing or two about valves (and how reliable they were if not switched off!). We have him (amongst many others) to thank for the success of Bletchley Park.
ForOldHack 2y ago
Brilliant! and warming. ( literally and figuratively. ) "My family was homeless when I was born. But my parents found work, the council found us a flat, and 20 years later my dad was the managing director of a very large engineering firm, and my parents built a fabulous home. To cut a long story short, much later my parents had a few personal problems, and sadly my mum finally killed herself. I don’t think you ever get over it, you really just learn to live with it. My life then went a bit pear shaped. I trusted bad people and guess what, really bad things happened. Very kind friends managed to put me back on my feet, and then, at 55, I met Judy and her family, and we’ve had the most wonderful 15 years together. So please, what ever happens, please don’t give up."
- xupybd 2y ago
  I'd really love to know more about him. That seems super interesting. Also to see this level of creativity after retirement is encouraging.
  - equestria 2y ago
    In my experience, it's more common than we suspect. I've met quite a few people in their 60s with fascinating hobbies. Some of it boils down to the fact that they had many decades to get good - and with career in the rearview mirror and adult children, they have a lot more time, too. But it's also true that with age, you lose the drive to get praise from strangers - so at best, you get a text website viewed by hundreds, not a series of TikTok or YouTube videos viewed by millions. And sometimes, not even that website. When that person dies and leaves behind a man-sized vacuum tube computer, or a collection of vintage calculators, or something of that sort... the heirs usually don't have the willpower to carry on, and because the stuff is impossible to sell, it's often destined for the dump. Maybe a couple of years in a storage unit before that. It's even worse with digital assets. Who's gonna renew that hobby domain or pay that hosting bill? I've seen some really valuable online resources disappear after the author died.
    - anyfoo 2y ago
      > Who's gonna renew that hobby domain or pay that hosting bill? I've seen some really valuable online resources disappear after the author died. This is why the Internet Archive is so important.
akdor1154 2y ago
> The IBM700 series was the most successful 1950s computer system. ... Able to handle 36 bit words using 18 bit instructions, it could be rented for $12,000 a month. That's cheaper than an AWS p4d.24xlarge.
- deleted 2y ago
  [deleted]
- ChrisMarshallNY 2y ago
  Not if you scale those dollars to 2024 Buck$. Back then, $12,000 was a lot of money. You could rent a whole office building, yearly, for that (actually, you could probably buy it, outright). These days, there are flats in NY and SF that go for more than that.
- Yawrehto 2y ago
  Apparently 12,000 dollars in 1959 even is over $100,000 today: https://measuringworth.com/dollarvaluetoday/?amount=12000&from=1959 https://measuringworth.com/dollarvaluetoday/?amount=12000&fr...
klodolph 2y ago
> Vacuum Tubes require high voltages to work efficiently and are not for the faint hearted. People used to build vacuum tube circuits on breadboards at home back in the 1950s. They seem pretty frightening by today’s standards, but they’re a lot like big, hot, high-voltage, low-current transistors. The low-power tubes used for signals are not that hot, just kind of warm. I’m not really criticizing here, I just want people to think of vacuum tubes as accessible to people with any kind of electronics background, and just more inconvenient than transistors.
- neuralRiot 2y ago
  Most people will get frightened by a medium-high or high voltage, but low voltage at high currents needs care too, a small short circuit could mean a huge fire. When I was studying we had to disassemble a decomissioned tube computer, the tubes were the sub-miniature type, the double triodes were just a bit bigger than a incandscennt christmas tree light bulb.
  - deleted 2y ago
    [deleted]
- TheOtherHobbes 2y ago
  Plate voltages can exceed the skin breakdown voltage of ~450V, which potentially makes them more dangerous than a domestic mains supply.
  - klodolph 2y ago
    Start with 150 V instead. You probably don’t need voltages that high. DIYers can stick with 200 V or something reasonable. The remaining people who deal with 450 V are probably servicing guitar amps. Plate voltages can exceed much more than 450 V. The 811A is rated for 1500 V of plate voltage. But the same is true for transistors—you can find transistors with similar voltage ratings.
bezkom 2y ago
How long before an audio manufacturer will implement some kind of DSP on this thing and marketing it as having "tube warmth"?
ginkgotree 2y ago
I build Vacuum tube audio amplifiers, mostly Push-Pull class A's with EL84s. This is next level. Absolutely awesome!!
- Optimal_Persona 2y ago
  Ooh those must sound glorious! I've never played through one, but have been close to Vox AC30 guitar amps cranked up loud! For non-musician HN'ers, if you've heard Brian May with Queen, that's the sound of overdriven Class A EL84s!
unit149 2y ago
>using 18 bit instructions, it could be rented for $12,000 a month. Release of the IBM700 utilized 6N3P diodes, that tend to burn out due to voltage alterations, until the 7000 series, with System 360 was transistorised.
kazinator 2y ago
It's possible to build a switch so that these 62NP tubes are interchangeable with 12AX7 (or ECC83). Instructions in this thread: https://www.diyaudio.com/community/threads/6n2p-ev-vs-12ax7.321760/page-2 https://www.diyaudio.com/community/threads/6n2p-ev-vs-12ax7.... Pins 9 and 5 of the tube socket must be galvanically disconnected from the PCB. The switch is then interposed there.
deleted 2y ago
[deleted]
hilbert42 2y ago
Wonderful project. I learned vacuum and solid-state electronics in parallel so I'm familiar with tube electronics. My fascination with valves go back to my early childhood when I used to move our console-type radio from the wall and touch the grid-1 spigot connection which would make a loud humming sound much to the horror and chagrin of my parents. One of the problems I've witnessed with training in electronics these days is how little time is devoted to vacuum tube electronics. Perhaps that's a necessity given constraints of course time etc. but without an understanding of how vacuum tubes work an important part of one's understanding of the subject is missing. Vacuum tube technology is still a vitally important part of both electronics and of physics experimentation. For instance, magnetrons (microwave ovens, radar, etc.), klystrons, TWTs (travelling wave tubes), high power transmitting tubes (TV, FM) all rely on vacuum tech. So too do PMTs (photomultipliers) and imaging devices such as vidicons and orthicons. In physics, understanding thermionic emission is essential to understanding thermodynamics, so too cold cathode emission and related tech such as vacuum deposition, etc. Even electron microscopes and similar instrumentation relies on vacuum technologies. Unfortunately, now since the widespread adoption of semiconductor electronics much of that vacuum tech tends to be rather specialized so those who've an interest in learning the subject don't get any hands-on experience at an early age. What's great about this project is that it brings vacuum technology to the fore where it can be not only seen but also demonstrated. Learning the transfer characteristics of thermionic diodes and triodes is an excellent way to gain such experience. And to begin one doesn't have to go to such lengths as this amazing project, starting with a single tube superregenerative FM receiver is a good place to start.
taikahessu 2y ago
And future proof! Made me question my sanity for a moment. "© 2025 TheTubeComputer.com"
Aardwolf 2y ago
> They can switch several hundred million times a second, and in the 1950s they were combined with germanium diodes as the basis for many incredible computer designs. Whoa, I didn't know they could switch that fast! Because afaik vacuum tube computers were measured in thousands of mathematical operations per second
- volemo 2y ago
  I guess it’s highly dependent on the type of the tube. The documentation [1] for the 6N3P (the one Mike uses) talks about input resistance at 100 MHz, so the tube must handle at least as much. [1]: https://www.istok2.com/data/575/ https://www.istok2.com/data/575/
  - immibis 2y ago
    Keep in mind that's in relation to amplifying analogue frequencies around 100MHz. It doesn't necessarily mean you can make digital logic that runs at 100MHz
hoseja 2y ago
>They can switch several hundred million times a second Huh. Wasn't expecting that.
tempodox 2y ago
> © 2025 Plus, we get free time travel to boot! Great project, I love it.

232 points by elvis70 2y ago

Fuses help with the "bang", as do using 5U4 or other vacuum tube diodes in the power supply, which limit current. I've learned not to be absolutely frightened of B+ at 200-300 volts, though I definitely respect it. Once you get above 500 volts, and an amp... the danger is very real, and the fear returns, in spades.

monocasa 2y ago
That being said, the biasing voltages get crazy too, leading to the big boy voltages. 300v b+ combined with 200v c- means that you're at 500v of potential if you short the wrong bits that are probably right next to eachother.
- peatandrepeat 2y ago
  Exactly why I keep wooden chopsticks in my amp repair kit. But the voltage is moot without the amperage to back it up, and most power transformers will happily supply it in heaps.

ownlife 2y ago

"The basic, domestic quality thermionic tubes have codes for a projected life span of either 1500 (6Н3П-Е) or only 500 hours (6Н3П). Many were used and then stored for over 50 years, quality stamps may have been accidentally altered, so life expectancy may be questionable, both for the tubes and for me!" I love the idea of an expiration date, or at least an ever-present need for repair. It emphasizes the idea that the computer is a machine, subject to the constraints of the physical world. There's something charming about that.

fortran77 2y ago
I restore a lot of 50s era tube radio equipment. The tubes are suprisingly robust! I'm surprised at how many times _resistors_ go bad, and of course we all know that capacitors fail. But more often than not, all the tubes in a typical 5 tube AM radio I find are working.
- dhosek 2y ago
  Radio Shacks¹ used to have a tube tester machine in them.² I was always impressed that there was such a finite universe of tubes that a single machine could test all of them. ⸻ 1. For the kids, this was a store that sold various electric gizmos including radios and circuit components, then later computer and televisions. 2. I think they may have also been present in hardware stores as well.
  - euroderf 2y ago
    There was a tube tester in our town's main pharmacy. So in principle you could pull the main tubes from (say) your TV and have at it.
  - quercusa 2y ago
    There's a HeathKit one up on Ebay now: 'Heathkit TC-3 Tube Tester'
  - themadturk 2y ago
    I remember tube testers at grocery stores when I was a kid. I'd go with my dad to test tubes from our TV set, and buy replacements for burned out ones.

retrac 2y ago

Bit of an aside but I wonder how far tube technology might have advanced, without semiconductors intervening. In the late 1950s and early 1960s, GE, IBM, and RCA, probably other companies, were working on "integrated tubes" with many components in a single envelope, as well as techniques for easier and more automated manufacture. For example, introduced in 1959: https://upload.wikimedia.org/wikipedia/commons/b/ba/Nuvistor_530.jpg https://upload.wikimedia.org/wikipedia/commons/b/ba/Nuvistor...

Animats 2y ago
> Bit of an aside but I wonder how far tube technology might have advanced, without semiconductors intervening. There were Compactrons. There were subminiature vacuum tubes.[1] A one piece printed circuit board of glass, with multiple tubes, might be possible. A glass plate made with lots of recesses, electrodes and wiring created by photo-etching like printed circuit boards, a glass plate on top, pumped down to vacuum and sealed. A low-density integrated tube. That's what a plasma panel display is. It's an integrated array of neon lamps. In a vacuum fluorescent display, each illuminated element is a triode vacuum tube. So it's quite possible to fabricate a big array of tubes. Maybe something like a ball grid array would work for external connections. Probably could have been done if necessary. Density probably would have maxed out around the density of elements on on the most dense vacuum fluorescent displays. Maybe devices at 1mm scale, or 1,000,000 nm. Good enough for mainframes and minicomputers, but not microprocessors. [1] https://archive.org/details/The_MIT_Museum_The_Subminiature_Vacuum_Tube_The_Cycle_of_Technology https://archive.org/details/The_MIT_Museum_The_Subminiature_...
adrianmonk 2y ago
Would tube reliability have limited how much you could scale it up? As far as I know, tubes have a limited lifetime and burn out eventually. If you have a million or a billion of them, they might fail so fast that your computer simply doesn't work. I don't know whether reliability is a solvable problem. Tube-based devices were once very common, so that suggests it would have been solved if it could have been.
- klodolph 2y ago

marcodiego 2y ago

For a long time I've been thinking about building one based on relays. The problem is that I would need a lot of relays just to achieve anything very simple. My solution: think about the simplest computer architecture I could come up with, and the simplest one was a NAND computer. In this architecture, the program is a simple loop with instructions all in the same format: input addess 1, input address 2, output address. The only supported instruction simply writes at the output address the result of a NAND operation of the input addresses. Since any circuit can be built using only NAND's, this computer can simulate any circuit, including the circuit of a Turing complete CPU. It certainly would be very slow, but relatively simple to build. I still have to think about a good type of memory for this machine. Maybe one day I'll take the courage to build it.

fragmede 2y ago
http://nandgame.com http://nandgame.com might help with that
mrob 2y ago
For something simpler than the computer described in the article, you might be interested in Usagi Electric's UE-1 vacuum tube computer. Construction is nearing completion, and it's documented on Youtube: https://www.youtube.com/playlist?list=PLnw98JPyObn0v-98gRV9PfzAQONTKxql3 https://www.youtube.com/playlist?list=PLnw98JPyObn0v-98gRV9P... This is a 1-bit design based on the Motorola MC14500B: https://en.wikipedia.org/wiki/Motorola_MC14500B https://en.wikipedia.org/wiki/Motorola_MC14500B Code executes directly from a literal loop of paper tape, so the clock speed is very slow. I expect this design would also work with relay logic.
- anyfoo 2y ago
  Yes, code executes directly from a literal loop of paper tape, and more specifically, there is only one loop (the paper tape loop), and every instructions executes at every iteration. Yet it can do what any other computer can do (in terms of computation, not I/O), because not every instruction has to actually effectively do something in each iteration, and it is a cornerstone of theoretical computer science that you can transform every program into one represented in an academic language called "WHILE", which is restricted to exactly that principle: It only consists of a single outer WHILE loop, and then inside the loop you have a bunch of conditions.

Calimax 2y ago

[dead]

EMIRELADERO 2y ago

So, if this became sufficiently popular to a degree in which many more units like these were produced and released, and it was decided that they all should be connected somehow, in a sort of inter-network... ...it would finally be a series of tubes.

debo_ 2y ago

From the website: The person who built this appears to be (at least) 70 years old. Amazing! > My family was homeless when I was born. But my parents found work, the council found us a flat, and 20 years later my dad was the managing director of a very large engineering firm, and my parents built a fabulous home. > To cut a long story short, much later my parents had a few personal problems, and sadly my mum finally killed herself. I don’t think you ever get over it, you really just learn to live with it. > My life then went a bit pear shaped. I trusted bad people and guess what, really bad things happened. Very kind friends managed to put me back on my feet, and then, at 55, I met Judy and her family, and we’ve had the most wonderful 15 years together. > So please, what ever happens, please don’t give up.

lalabert 2y ago

“So please, what ever happens, please don’t give up.” Love that - thank you!

lalabert 2y ago

Tommy Flowers (https://en.wikipedia.org/wiki/Tommy_Flowers https://en.wikipedia.org/wiki/Tommy_Flowers) knew a thing or two about valves (and how reliable they were if not switched off!). We have him (amongst many others) to thank for the success of Bletchley Park.

ForOldHack 2y ago

Brilliant! and warming. ( literally and figuratively. ) "My family was homeless when I was born. But my parents found work, the council found us a flat, and 20 years later my dad was the managing director of a very large engineering firm, and my parents built a fabulous home. To cut a long story short, much later my parents had a few personal problems, and sadly my mum finally killed herself. I don’t think you ever get over it, you really just learn to live with it. My life then went a bit pear shaped. I trusted bad people and guess what, really bad things happened. Very kind friends managed to put me back on my feet, and then, at 55, I met Judy and her family, and we’ve had the most wonderful 15 years together. So please, what ever happens, please don’t give up."

xupybd 2y ago
I'd really love to know more about him. That seems super interesting. Also to see this level of creativity after retirement is encouraging.
- equestria 2y ago
  In my experience, it's more common than we suspect. I've met quite a few people in their 60s with fascinating hobbies. Some of it boils down to the fact that they had many decades to get good - and with career in the rearview mirror and adult children, they have a lot more time, too. But it's also true that with age, you lose the drive to get praise from strangers - so at best, you get a text website viewed by hundreds, not a series of TikTok or YouTube videos viewed by millions. And sometimes, not even that website. When that person dies and leaves behind a man-sized vacuum tube computer, or a collection of vintage calculators, or something of that sort... the heirs usually don't have the willpower to carry on, and because the stuff is impossible to sell, it's often destined for the dump. Maybe a couple of years in a storage unit before that. It's even worse with digital assets. Who's gonna renew that hobby domain or pay that hosting bill? I've seen some really valuable online resources disappear after the author died.
  - anyfoo 2y ago
    > Who's gonna renew that hobby domain or pay that hosting bill? I've seen some really valuable online resources disappear after the author died. This is why the Internet Archive is so important.

akdor1154 2y ago

> The IBM700 series was the most successful 1950s computer system. ... Able to handle 36 bit words using 18 bit instructions, it could be rented for $12,000 a month. That's cheaper than an AWS p4d.24xlarge.

deleted 2y ago
[deleted]
ChrisMarshallNY 2y ago
Not if you scale those dollars to 2024 Buck$. Back then, $12,000 was a lot of money. You could rent a whole office building, yearly, for that (actually, you could probably buy it, outright). These days, there are flats in NY and SF that go for more than that.
Yawrehto 2y ago
Apparently 12,000 dollars in 1959 even is over $100,000 today: https://measuringworth.com/dollarvaluetoday/?amount=12000&from=1959 https://measuringworth.com/dollarvaluetoday/?amount=12000&fr...

klodolph 2y ago

> Vacuum Tubes require high voltages to work efficiently and are not for the faint hearted. People used to build vacuum tube circuits on breadboards at home back in the 1950s. They seem pretty frightening by today’s standards, but they’re a lot like big, hot, high-voltage, low-current transistors. The low-power tubes used for signals are not that hot, just kind of warm. I’m not really criticizing here, I just want people to think of vacuum tubes as accessible to people with any kind of electronics background, and just more inconvenient than transistors.

neuralRiot 2y ago
Most people will get frightened by a medium-high or high voltage, but low voltage at high currents needs care too, a small short circuit could mean a huge fire. When I was studying we had to disassemble a decomissioned tube computer, the tubes were the sub-miniature type, the double triodes were just a bit bigger than a incandscennt christmas tree light bulb.
- deleted 2y ago
  [deleted]
TheOtherHobbes 2y ago
Plate voltages can exceed the skin breakdown voltage of ~450V, which potentially makes them more dangerous than a domestic mains supply.
- klodolph 2y ago
  Start with 150 V instead. You probably don’t need voltages that high. DIYers can stick with 200 V or something reasonable. The remaining people who deal with 450 V are probably servicing guitar amps. Plate voltages can exceed much more than 450 V. The 811A is rated for 1500 V of plate voltage. But the same is true for transistors—you can find transistors with similar voltage ratings.

bezkom 2y ago

How long before an audio manufacturer will implement some kind of DSP on this thing and marketing it as having "tube warmth"?

ginkgotree 2y ago

I build Vacuum tube audio amplifiers, mostly Push-Pull class A's with EL84s. This is next level. Absolutely awesome!!

Optimal_Persona 2y ago
Ooh those must sound glorious! I've never played through one, but have been close to Vox AC30 guitar amps cranked up loud! For non-musician HN'ers, if you've heard Brian May with Queen, that's the sound of overdriven Class A EL84s!

unit149 2y ago

>using 18 bit instructions, it could be rented for $12,000 a month. Release of the IBM700 utilized 6N3P diodes, that tend to burn out due to voltage alterations, until the 7000 series, with System 360 was transistorised.

kazinator 2y ago

It's possible to build a switch so that these 62NP tubes are interchangeable with 12AX7 (or ECC83). Instructions in this thread: https://www.diyaudio.com/community/threads/6n2p-ev-vs-12ax7.321760/page-2 https://www.diyaudio.com/community/threads/6n2p-ev-vs-12ax7.... Pins 9 and 5 of the tube socket must be galvanically disconnected from the PCB. The switch is then interposed there.

deleted 2y ago

[deleted]

hilbert42 2y ago

Wonderful project. I learned vacuum and solid-state electronics in parallel so I'm familiar with tube electronics. My fascination with valves go back to my early childhood when I used to move our console-type radio from the wall and touch the grid-1 spigot connection which would make a loud humming sound much to the horror and chagrin of my parents. One of the problems I've witnessed with training in electronics these days is how little time is devoted to vacuum tube electronics. Perhaps that's a necessity given constraints of course time etc. but without an understanding of how vacuum tubes work an important part of one's understanding of the subject is missing. Vacuum tube technology is still a vitally important part of both electronics and of physics experimentation. For instance, magnetrons (microwave ovens, radar, etc.), klystrons, TWTs (travelling wave tubes), high power transmitting tubes (TV, FM) all rely on vacuum tech. So too do PMTs (photomultipliers) and imaging devices such as vidicons and orthicons. In physics, understanding thermionic emission is essential to understanding thermodynamics, so too cold cathode emission and related tech such as vacuum deposition, etc. Even electron microscopes and similar instrumentation relies on vacuum technologies. Unfortunately, now since the widespread adoption of semiconductor electronics much of that vacuum tech tends to be rather specialized so those who've an interest in learning the subject don't get any hands-on experience at an early age. What's great about this project is that it brings vacuum technology to the fore where it can be not only seen but also demonstrated. Learning the transfer characteristics of thermionic diodes and triodes is an excellent way to gain such experience. And to begin one doesn't have to go to such lengths as this amazing project, starting with a single tube superregenerative FM receiver is a good place to start.

taikahessu 2y ago

Aardwolf 2y ago

> They can switch several hundred million times a second, and in the 1950s they were combined with germanium diodes as the basis for many incredible computer designs. Whoa, I didn't know they could switch that fast! Because afaik vacuum tube computers were measured in thousands of mathematical operations per second

volemo 2y ago
I guess it’s highly dependent on the type of the tube. The documentation [1] for the 6N3P (the one Mike uses) talks about input resistance at 100 MHz, so the tube must handle at least as much. [1]: https://www.istok2.com/data/575/ https://www.istok2.com/data/575/
- immibis 2y ago
  Keep in mind that's in relation to amplifying analogue frequencies around 100MHz. It doesn't necessarily mean you can make digital logic that runs at 100MHz

hoseja 2y ago

>They can switch several hundred million times a second Huh. Wasn't expecting that.

tempodox 2y ago