Telephone central exchanges used to have enormous lead acid battery (like automobile batteries, the starter motor not the EV kind) arrays if they lost power.
It was amazing to see the battery array discharge ammeter at 5000 amps when utility power went out.
some ISP's still do (or did, last time I was in one), at least one I worked for a few years back. Had a room full of lead acid batteries on shelves and another with a big spinning wheel to smooth out the flow.
Neither silicone hardware nor tube hardware goes literally cold in a cold boot; just the power is cut for a moment, usually not long enough to lose a lot of heat.
The difference is that for solid-state logic, the heat is purely a waste byproduct, whereas for thermionic valves, the heat is the energy used by the electrons to move between the electrodes, hence the name. If the valves are cold, you have to wait for them to warm up before they can do anything.
All the same, "cold boot" doesn't refer to letting tubes cool down. If power is restored while the tubes are still hot, it's still a "cold boot".
The electrons are not moved by heat; they are moved by the electric potential between the electrodes. The heat goes into maintaining the cathode at a certain temperature, at which the electrons "boil off" in sufficient numbers, but that requires only a smidgeon of the energy. Though depending on it, tubes are incredibly wasteful of heat.
So you say silicon and other parts don't require heat? Check that data sheet again! If the part's operating range is from -40°C to 70°C, then that part requires heat. If the ambient temperature happens to be -100°C, you have to heat it, perhaps by installing a heating filament into the chassis.
E.g. check the TI datasheet for the NE5532 op-amps:
Free air operating temperature:
NE5532, NE5532A: 0 to 70°C.
SA5532, SA5532A: –40 to 85°C.
(That standard part is quite delicate there, only down to zero!)
Conversely, thermionic tubes for a hot environment could be built without heating filaments. If the ambient temperature is 500°C, and that happens to be quite enough for that tube's cathode, then it Just Works, like your NE5532 IC at 3°C.
Is this known to work? I would have thought that running a whole tube at high temperature would cause the grid to emit thermal electrons, creating a current between grid and plate. Even though the grid doesn't have the low-work-function coating that the cathode does, its surface area can be larger and it's usually more negative than the cathode so I'd expect substantial currents.
If this does work, you could save a lot of power by building heated, insulated enclosures for entire tube appliances rather than heating each cathode and cooling every tube.
"Conversely, thermionic tubes for a hot environment could be built without heating filaments. If the ambient temperature is 500°..."
There's a lot of physics and engineering behind thermionic emission in a typical vacuum tube and the subject shouldn't be overlooked just because tubes are less commonplace than they once were.
Until the transistor became popular in the latter half of the 20th C. essentially all of electronics relied upon thermionic emission so much effort went into understanding it. Moreover, it's still very important in specialized areas such as in scientific instruments, high power transmitting tubes, TWTs (Traveling Wave Tubes), CRTs, etc.
Thermionic emission obeys Richardson's Law—after physicist Owen Richardson who received the Nobel Prize for his work in 1928, and its study is an essential part of thermodynamics: https://en.m.wikipedia.org/wiki/Thermionic_emission.
When I was learning about this stuff I had a little book titled Thermionic vacuum tubes and their applications by Sir Edward Appleton (who is more famous for his wartime research into radar). Still, for anyone who's interested in thermionic emission then this could be a useful reference.
I'd add that when it comes to practical methods of manufacturing thermionic cathodes, info on low work function oxide emitters etc. then there are references that are better or more practically orientated (but offhand I cannot remember the names of any).
The meanings we give them today go back almost 50 years.
Then the trail runs cold, pardon the pun.
According to Google n-gram searches, "cold reboot" and "warm reboot" didn't exist at all until the late 1970s.
Related terms like "cold boot" and "warm boot" come up, but only in references to footwear. Can't find any computer uses 1950-1970.
The "cold start" and "warm start" mostly come up in automotive, aviation or marine contexts, confounding the search. Likewise, not finding computer uses.
Not finding computer uses for "cold restart" and "warm restart", either.
All these terms take off as computer terms in the late 1970's.
By the way, an important feature of the warm reboot is (possibly) that data is still in memory (if you have the kind of machine whose memory is wiped when power is cut, not magnetic core). In machines with simple operating systems, you could recover your program or data from memory after a reset.
(I think the timeline in the n-grams coincides with the explosion in microcomputing and reflects that: penetration of the jargon into mainstream writing. Nevertheless, the case doesn't seem to be good though for a vacuum tube origin of warm {start/restart/reboot}.)
Silicone is a rubber made to make good kitchen utensils. The crummy plastic ones tend to be nylon or the like. Biggest tell is that silicone does not melt.
Take heart, you're not alone, my WP's speller has automatically corrected to 'silicone' on more than one occasion and I've not noticed the embarrassing mistake. ;-)
Filaments experience a high inrush current on startup because their resistance is lower when they are cold. That's why incandescent bulbs often burn out on powerup, rather than in the middle of a duty cycle.
Tube filaments last a good long time though, particularly in small signal tubes.
They do not shine like light bulb filaments; they glow red.
The circuit designer also has a say in it; tube filaments can be operated over a range of currents: you can run tubes hotter or colder. In a digital application, you'd probably want to go as cold as you can get away with for longer life.
Tubes have various modes of failure in addition to burned out filaments, like "gassing out", or the cathode emission decreasing, eroding the gain. Of course, abnormal conditions like parts melting from overcurrent.
Speaking of incandescent bulbs: those are victims of planned obsolescence. A bulb can easily be made that will last 50 years; it's just not profitable because you can't charge 50 times more for it than one that burns out in a year. Once everyone has 50 year bulbs, you're out of business.
> Once everyone has 50 year bulbs, you're out of business.
This seems to have been the issue with the expensive Philips Hue LED bulbs (the ZigBee ones). We installed ours close to a decade ago, and we took them with us when we moved to a new house. I don't think I've replaced a single one yet.
Philips seems to have de-emphasized that set of bulbs in favor of cheaper models, as far as I can tell?
in the music world, variacs are used to bring old tube amplifiers up to power slowly for that reason. not after being repaired or refurbished generally, but certainly when the amp's condition is unknown. the author of tfa said his new power supplies do that automatically, which is pretty neat.
That wouldn't be on account of the tubes; tube filaments do not take minutes to heat up the cathodes.
Warm boots can save time by not repeating all the boostrapping steps. In a warm boot, you typically don't execute any power-on self-checks, for starters.
Maybe I'm misremembering (I was very young) or maybe I was with people who were too superstitious, but these tubes themselves were actually from the 1950s, and they did indeed take a significant amount of time before they decided the hardware was "warm enough" that one could let the software start doing its thing.
> Hold out for the partner that cheers you on when you're doing what you love.
If only it were that easy. Those kinds of people are few and far between. I’m almost 50 and I don’t think I’ve ever even met a woman who has actively encouraged me about a single thing. I’ve been married twice and have 4 daughters.
You must advertise to potential mates who you are from the start, so that you naturally attract those who like your deal and chase away those who don't.
I met my second wife this way, and our 6 years together were the best of my life. She was killed by a Russian tank in Ukraine in January, and I miss her more than anything.
You're not correct, and I could go into detail as to why the things that happened in my past happened, but I can say with complete confidence that you are wrong.
Putin is a cancer on the Earth and if Trump wins he will be in control of the US as well.
Humans, generally, are absolute shit creatures, and I dearly hope that our species goes extinct.
I think the problem is that I expect human beings to be nice and supportive.
I've never personally witnessed anyone being truly supportive of anyone else, ever in my entire life. Everyone just makes fun of everyone else, and blames others for the problems they are having, just like you just did.
There’s a saying, if everywhere you go smells, check your shoe.
I have had the opposite experience in life. There are people out there who I would support through what they’re doing, and those people support me no matter how silly it is. I’m in a band, and we’re recording an album at the moment. It’s costing us money and an enormous of time to do it but my partner supports me doing it because she knows i enjoy it.
I am really tired of being blamed for the behavior of other people. are you going to blame me for what you said above, too? "It's your fault I said that it was your fault."
humans suck and it is proven to me again every single day.
Hence the hold out. I (50m) didn’t meet her until I was 30: until that time I dated and had few months relationships with a lot but it never felt quite right. Which became blatantly obvious when I met my wife.
Same here, but it took me much longer than that. Partners like this are out there, but in my experience they're somewhat rare, plus you still have to deal with all the other compatibility/attraction issues present in dating (i.e., you might meet someone who's really lovely and supportive, but they're just not romantically interested in you, or the two of you just don't make a great couple for some reason).
One piece of advice I do have, though: hold out for someone who's a great partner who you really enjoy spending time with. Don't settle for someone who obviously isn't just because other people are pressuring you to "find someone".
It's not easy. I missed once but struck gold the second time. I'm sorry you haven't felt supported. It's really hard when you don't feel like you can just be yourself.
The problem is that you don’t know that you did struck gold until long time in. After having dates a lot of women, I found that just telling things straight like; religion/conspiracy theories etc are off the table, no alternative shite, I want no kids, ever, I like beer, I believe in friends before family etc did converge much faster than anything else. I know that I cannot work with anyone that doesn’t have the same ideas, however then still, on a multi decade scale, it has to prove itself and there the love and respect comes in I think. Everyone has issues, but if they don’t change the fundamentals stated in the first date as said above, it has a good chance. I would only leave if my wife got religious or wants kids; the rest we can fix.
This guy is the right kind of crazy. This is truly what the internet was made for: sharing our outlandish, over-the-top projects with others. Awesome writeup!
I'm actually surprised by the figure, though. A small tube requires about 300 mA at 6 V, and the trick is that you can connect the heaters in series instead of doing it all in parallel and pumping out a ton of amps at a very low voltage.
They could've done 10 tubes in series at a reasonably safe 60 VDC, and they'd only need 20 amps.
Back in that era, because both valves and relays were expensive, it was also common to use them more creatively than just constructing standard logic gates. You'd try to make a full adder or a flip-flop cell as an analog circuit, breaking the abstractions we're now used to - but also saving components.
"They could've done 10 tubes in series at a reasonably safe 60 VDC, and they'd only need 20 amps."
Thermionic vacuum tubes of this type usually have a specified maximum heater/cathode voltage rating which varies considerably according to design. Exceeding that rating and one risks a short between the heater and cathode. For these types of tubes heaters can safely operate up to 200V negative with respect to the cathode and about 100V positive.
In my post I suggested substituting a tube that's more common in the West—the 12AT7, it has the advantage of having a 'tapped' heater which means it can be wired in parallel mode to operate at 6.3V or in series mode at 12.6V. At 12.6V the current would be halved: https://en.wikipedia.org/wiki/12AT7 (pins 4 and 5, the tap on pin 9).
When I was in high school (many decades ago now) we had a vacuum tube tester with a switch that allowed you to select the heater voltage. We quickly discovered, devils that we were, that if you stuck a simple diode with a 1.5 V heater in the tester and cranked the voltage to max it would launch like a little rocket. Eye protection recommended.
"We quickly discovered, devils that we were, that if you stuck a simple diode with a 1.5 V heater in the tester and cranked the voltage to max it would launch like a little rocket."
Where I once worked we had several AVO Mk III valve testers† which we used in a nice little "demo" (for want of a better word) for both new employees and non-electronics types who'd occasionally wander into the engineering/electronics department.
We'd take a 7 or 9-pin miniature valve (preferability 9-pin) and place it under water and break the evacuating seal on its top, being evacuated the valve would instantly fill with water. Now with suitable settings on the AVO we'd get the water to boil with steam bubbling out of its top. This all happened whilst we nonchalantly went about our business pretending that nothing unusual was happening.
Sometimes the reaction from the newcomers/visitors was so funny that those of us who couldn't keep a straight face would quickly exit the lab and burst into hysterical laughter.
That was party trick number one, there were more: half fill a CRT with water by the same process and put it back into the monitor for some poor unsuspecting tech to discover. Another was our famous CO2-powered valve gun which we'd use to shoot 7-pin and 9-pin valves at high speed across the carpark aimed at the door of the electricians' department with whom we were continually at war. The valves would embed themselves in the wooden door up to the full length of their pins and rarely would the glass break. Electricians would come in next morning to find our little gifts awaiting them.
Yet another was the exploding electrolytic capacitor under one's seat. And there are many more to tell.
Believe it or not, we were quite a professional outfit and our work output was excellent. But it was the funniest and most enjoyable place I've ever worked at.
I did a quick search for the specs, and, if I am reading it right, Wikipedia [1] gives the filament current as being 350mA at 6.3V, a dissipation of 2.2W. As that current sums to 196A for the 560 tubes, I suspect this is what the 200A figure refers to.
As the tubes are at high vacuum, they are already well-insulated, so I imagine that most of the heat loss is via infra-red radiation. I have a very vague recollection that, in thermionic tubes, the anode has to be kept reasonably cool so that it is not emitting electrons itself. I would be surprised if there are any low-hanging fruit to be plucked here, especially given that vacuum tubes were important technology for a half-century.
"Could you lower the current requirement by thermally insulating the tubes?"
The thermionic effect is very interesting, if the right material is used to coat the cathode then very large emissions can be had. Combinations of oxides such as barium, strontium and others can have both low work functions and high emissions. Currents in the region of over 100A/sq cm can be achieved.
Thus, valves/tubes could be designed to be much smaller and have much smaller currents. For a digital application such as this only a very small cathode current would be needed, this then would mean a much smaller heater could be used.
In the past, miniaturizing vacuum tubes was desirable but wasn't a major priority and further development was stopped when the transistor became available.
That said, in the 1950s portable tube radios were available that used much less heater power than their mains-operated counterparts, for example tubes like the 3V4. It has a directly-heated cathode and a filament/ heater voltage of 1.4V and current of only 100mA (in series mode it operates at 2.8V at only 50mA).
The directly-heated cathode (meaning that the heater is the cathode) tubes have another advantage: they are nearly instant turn-on, no warm-up needed. Same as vacuum fluorescent displays.
Very old 1920s tubes also used direct cathodes (but used a huge amount of heater power). If you look at the circuits, they had to jump through hoops to have the desired grid to cathode bias while at the same time providing the heater current. I think this would be easier for logic gates: set all of them to ground.
"Very old 1920s tubes also used direct cathodes (but used a huge amount of heater power)."
Yeah, and not-so-old ones too (that is, ones designed in the 1940s). I've a couple of 100TH power triodes whose directly heated thoriated tungsten cathodes consume just over 30 Watts (5V @ 6.3A) yet their plate dissipation is only around 100W. That's pretty miserable efficiency. (They look very pretty when working though.)
You're right about jumping through hoops, circuis become messy and contorted. Also, there's the messy business of eliminating AC filament hum, thus the commonplace practice of using a humdinger circuit on directly-heated triodes such as the 2A3.
Nearly instant turn on can also be a disadvantage when they're used as rectifiers. Tubes like 80, 5Y3G, 5R4G, etc. supply HT long before loading occurs from the indirectly heated ones. In unregulated or poorly designed power supplies it can put additional strain on the PS's electrolytic capacitors.
I've often wondered why rectifiers, especially low power one like those mentioned, remained so popular for so long—or why it took so long for indirectly-heated, unipotential cathode tubes such as the 6X4 to become popular. Cost and ease of manufacturing I suppose.
Current into a low-resistance "heater" element is used to produce the heat required for Thermionic Emission [0] in a vacuum tube. You only need the heater/emitter to be hot, and insulating the tubes would just spread the heat around to everything inside of it — at some extreme, making everything into an emitter, instead of elements that control the emission.
This is not really accurate. To get meaningful emissions from normal electrodes, you need to heat them up to about 2000 °C. Vacuum tubes operate at 700 °C or something like that. The trick is that one electrode is doped with special rare-earth additives that greatly increase electron emissions. The same treatment isn't applied to the rest of the device. So, even if all internal components have the same temperature, a vacuum tube can still work (to some extent).
100% correct and I appreciate the additional details! I couldn't come up with a good analogy to explain you want the emitter as a separate and unique element from everything else involved in a tube — oversimplified in the process.
Really it's both ways in terms of required current. The thermionic effect requires filament heat, which since being a filament, take some amount of current, often around half an amp, some more some less. A filament could, in theory, be run at any current though so long as the power through the filament stays the same and the voltage is kept low enough not to arc to adjacent parts. There is likely also a minimum current requirement (since you need a source for those free electrons), which often then implies some non-linearity at the low end.
As others have mentioned, the 200amps of this case could be reduced substantially by running filaments in series (can be done with 6.3v heaters as the error from a common 5v or 9v supply is more than if you pair them up and use a 12V supply) though this introduces the failure mode of old Christmas tree lights.
There are tubes made which share one heater. For an exotic example with a working web page, see this tube where two triodes and one pentode share the same one heater filament.
And in this very design, they chose "6N3P valve contains 2 triodes around a single heater, halving the physical size and power requirements."
There may have been tubes made where the triode function can be pretty rough (sufficient for a digital circuit) and several of them could share one enclosure. In the tubes shown above, apparently the limit was the number of pins on the socket - but also that all these active elements do not share any pin.
Insulating the whole thing would run into issues like burning wire insulation.
Perhaps the inside of the tube could be coated with a thin layer of gold using evaporative deposition before the grid/plate/filament/etc is added, like on spacesuit visors for IR reflection.
The high voltage from my understanding is to be able to handle the high inrush current to the heaters on power up, I believe after that the requirements are lower (parroting what I've read written by Eric Barbour on his metasonix vacuum tube synthesizers)
Now I'd truly love that computer as a talking point in say the rumpus room of my house, I could entertain my techie friends for hours. And it would take on extra importance in winter in keeping my house warm.
I've not used 6N3P tubes before but looking at the circuit it seems to me a 12AT7 (an old favorite of mine) would substitute in that circuit almost without alteration. Then again with a tweak or two either the higher gain 12AX7 or its lower gain cousin the 12AU7 would do.
Having become accustomed to helping a friend fix old ham radio gear, 80 volts doesn't strike me as terribly dangerous.
In some of this stuff, over half of the power supplies output was dumped as heat in resistive divider networks just to bias things correctly and ensure operation. The filaments worked out to less than a fifth of the load in many cases.
Coming from a background of transistors and chips, it was wild to see so many 5 watt or more resistors in use.
This is so interesting! Quite often, I'm thinking about how a modern design would perform with tubes. Back in the 40s and 50s, digital computers were new. Much of the design was inherited from tabulating machines. When I study the early IBM machines, they seem very complex. When we learned more during the 60s, and ended up with microprocessors in the 70s, the design had been optimized a lot. So I have been wondering how a "modern" design would perform on tubes.
This guy actually did it. What a fun project it must have been. Super interesting read.
One detail in the introduction that made me a bit puzzled: "The Valve.Computer is an 8 bit computer, with the usual 12 bit address and data buses". In an 8 bit CPU, we had "the usual 16 bit address bus and the 8 bit address bus".
It's really cool to design all those NOR gates using thermionic valves, as shown in the schematics in the middle of the article. I just wonder if using two regular diodes in the input paths of each NOR gate and another diode in the output path is a little bit of "cheating", since diodes are somewhat newer technology than thermionic valves.
I was really hoping to see a picture of it in dim light with the valves glowing. Also I was not expecting to see such an adorable light house for ducks in the post. All around a great read :)
Oh the article is thoroughly on topic! I mean the comments related to Valve the company. The thread was filling up with those before we changed the title. (Submitted title was "Valve.computer".)
Sometimes when there are too many offtopic comments like this I make a stub comment, move all the offtopic subthreads underneath it, and then collapse it.
> Every one agrees that the Turner Prize is much more than just a display of virtue signalling by the cultural elite, and I have decided to enter the Valve.Computer for the prize.
Uh, what? Where did this sudden "virtue signaling" by the "cultural elite" stuff come from?
It wasn't until working with valve hardware that I finally grokked the original difference between a cold boot and a warm one.