For a little while vacuum tubes and semiconductors were fighting a heated battle for dominance, with bipolar junction transistors and 1959’s RCA Nuvistor both allowing you to build a compact circuit with relatively low power usage and no high voltages. Although we now know that semiconductor technology won out overwhelmingly, that doesn’t mean that you cannot build a brand new Nuvistor board in 2026, as [Eric Schlaepfer] AKA [TubeTimeUS] recently did.
Nuvistors saw their most use in small-signal radio frequency applications, like VHF and UHF, with excellent low-noise characteristics that saw them used until the early 1970s in television sets, radios and oscilloscopes, as well as in space probes like the 1960s US Ranger Moon missions, so by that metric they had a good run.
Nothing so exciting is built in this video, sadly, but alongside a breakdown on how nuvistors work, we do see a discrete 555-style timer built using a gaggle of tetrode nuvistors, giving a pretty good idea of what using them in a project is like. Being a vacuum tube at its core, nuvistors still have the heater element, which is what gives vacuum tubes their reputation for being slow to start working and large current draw.
Despite their drawbacks, nuvistors still have a range of benefits compared to modern-day transistors, including being practically immune to electrostatic discharge (ESD) and electromagnetic interference (EMI) all the way up an EMP that will destroy most semiconductor electronics.
That said, the somewhat limited 8-nuvistor implementation of the 555 had to get a few extra pins for the heater supply, which burns up about 7.5 Watt just to allow the circuit to function. Terming it the ‘hollow-state 555 timer’, it works effectively just like any semiconductor 555, just with that extra power cost and of course no significant prospect of making it smaller, barring a semiconductor evolution as with the pixels-sized CRTs in the SED and FED type displays.
We covered the nuvistor before, including a great reference on this device, and its history that was much longer than people often assume today, as well as the vacuum tubes we use every day in for example our microwaves.
That’s a very cute giant DIP package-style board. Yes I know that “DIP package” unpacks to “Dual In-line Package Package” kind of like saying “ATM machine,” leave me alone okay
DIP can also be used an abbreviation for “Dual Inline Plastic”, in contrast ti dual inline ceramic.
Cer-dip was what we called it where I worked. Plastic was p-dip.
That would have to be a DIC.
I rescued some nuvistor filled gear, and would like to build something useful with them. A high impedance input buffer might be a good thing. An e-field probe or lightning detector might be another.
As a 72 yr old engineer who cut his Twoteeth on tubes:
KUDOS TO BIG TIME!
IM GUESSIN 4 TUBES WERE USED AS 2 DIFFERENTIAL MasPS TO DO 1/3 AND 2/3 Vcc COMPARATORS.
Then 2 more uses as the SR flip flop.
One more as pin 7 the capacitor discharge pin?
Designing a 100 MHz RF amplifier in 1975, I looked at nuvistors and found them to have noise characteristics no better than the best MOSFETS. The poor transconductance of vacuum devices make low noise voltage difficult. Semiconductor noise performance and bandwidth has continued to improve over the last 50 years.
Hm. The way it reads, it also could be interpreted the way that the old nuvistors were still able to compete with the best MOSFETs of the time.
That’s not bad, I think.
I often wonder how nuvistors would look today if the US industry (and the far east) hadn’t basically killed the tube/nuvistor through mass-production of low quality transistors.
Other places on earth still continued to use the tube technology for a little longer,
but international trade caused an end to this.
There were no “untouched”, isolated regions anymore where tube technology could have evolved while being undisturbed.
No far island or isolated mountain region etc.
This is very depressing, I think.
Because tube technology was more elegant than transistor technology, more ingeniuous, more human.
It was an improvement over the existing solid-state/semiconductor technology (detector crystal, glass diode).
It also allowed for a higher maximum frequency, was electrically robust.
The FET is closest to the thermionic valve, I think.
It’s basically an emulation of the real thing.
Maybe world’s first “emulator”. :)
Funny how all it takes is a change of perspective to go from “it kinda sucked” to “wow, it was pretty damned good”! 😊
“I often wonder how nuvistors would look today if the US industry (and the far east) hadn’t basically killed the tube/nuvistor through mass-production of low quality transistors.”
It wouldn’t have changed much and the far east production had a negligible impact. Transistors were also mass produced in Europe, but most of them ended up in equipment where the general public knew not much about the inner workings, like telecomms and computing. (You could build thousands of radios from the transistors in just one Telefunken or Bull mainframe.)
Nuvistors aren’t all that great, they are expensive to manufacture and not easy to design with. When they arrived on the market, they had to compete with cheap mass produced frame-grid UHF tubes for TV tuners (PC86, PC88, etc.) so they never made it into consumer appliances outside the USA. And not much later, the industry already started moving to integrated circuits…