Korg and Noritake develop modern vacuum tube - Page 1
Forum section: electronics / projects

author: grenert
author_rank: Frequent Contributor
timestamp: January 22, 2015, 07:01:44 pm
content: For you rockers out there O0The Japanese instrument manufacturer Korg and Noritake (of VFD fame) have created a modern version of the vacuum tube called the Nutube. It is 30% of the size and uses only 2% of the power of standard tubes.Now everybody can get tubes in their guitar amps!http://www.korg.com/us/news/2015/012207/

author: pickle9000
author_rank: Super Contributor
timestamp: January 22, 2015, 07:27:33 pm
content: I'm guessing it has a blue glow.

author: c4757p
author_rank: Super Contributor
timestamp: January 22, 2015, 07:31:00 pm
content: "ground breaking technology" - it's a VFD without the phosphor

author: free_electron
author_rank: Super Contributor
timestamp: January 22, 2015, 09:06:21 pm
content: modern <-> vacuum tube

author: Howardlong
author_rank: Super Contributor
timestamp: January 22, 2015, 09:26:07 pm
content: Nutube == Nuvistor ?

author: coppice
author_rank: Super Contributor
timestamp: January 23, 2015, 02:43:32 am
content: Quote from: grenert on January 22, 2015, 07:01:44 pmI thought Noritake's fame was making dinner plates.

author: zapta
author_rank: Super Contributor
timestamp: January 23, 2015, 04:06:56 am
content: Quote from: grenert on January 22, 2015, 07:01:44 pmIt's interesting that even such a mature technology can still be improved, especially the power reduction.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 23, 2015, 05:51:05 am
content: Is it just me or is that website's formatting utterly broken?Tim

author: coppice
author_rank: Super Contributor
timestamp: January 23, 2015, 05:59:44 am
content: Quote from: zapta on January 23, 2015, 04:06:56 amThey aren't really improving on anything. They are just reviving stuff that was appearing just as transistors made them irrelevant. There were some really minute valves, mostly developed to minaturise computers, and for military portable radios.

author: Fsck
author_rank: Super Contributor
timestamp: January 23, 2015, 06:28:06 am
content: Quote from: T3sl4co1l on January 23, 2015, 05:51:05 amthe website doesn't even work for me.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 23, 2015, 07:23:40 am
content: Wasn't there some article about a chip scale vacuum tube that used field emission instead of a filament?

author: coppice
author_rank: Super Contributor
timestamp: January 23, 2015, 07:37:22 am
content: Quote from: NiHaoMike on January 23, 2015, 07:23:40 amYes. That's another old (1980s) things which has come up again recently, being presented like its totally new.

author: helius
author_rank: Super Contributor
timestamp: January 23, 2015, 07:48:25 am
content: http://spectrum.ieee.org/semiconductors/devices/introducing-the-vacuum-transistor-a-device-made-of-nothingwas the article.Re: the VFD sans phosphor, it's strange to praise anamplification deviceas "using 2% power". Of course, that is what tubes do (besides rectification) in a guitar amp. "Using power" is the reason they are there!The phrasing of the press release implies that these devices are being used only to color the sound, not for amplification at all. Much like a hundred unremarkable Crate or Acoustic amps that came before.Korg is notorious for using vacuum tubes in their products that "glow" from strategically placed LEDs:

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: January 23, 2015, 08:37:53 am
content: Cool. Bring back the Nuvistor.http://en.wikipedia.org/wiki/NuvistorWouldn't mind getting hold of some small pencil valves for guitar effect pedal projects.This site has links to datasheets and stuff ==>http://amps.zugster.net/projects/subminiature

author: jeremy
author_rank: Super Contributor
timestamp: January 23, 2015, 08:40:04 am
content: Quote from: coppice on January 23, 2015, 02:43:32 amActually, I asked a noritake engineering in tokyo about this. They actually are famous for making both, and yes it is the same company.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 23, 2015, 09:04:41 am
content: Tubes aren't so bad, there are really only a few things bad about them:- Size- Dissipation (not always a disadvantage)- Heater- Operating voltage about 10 times higher; currents relatively low. High operating temperature also means high resistance to ambient heat (with suitable derating), and low tempco!Ignoring the other problems, the electrical implications of the last one limit their usefulness to lower frequencies or narrower bandwidths than solid state, hence there are few places they are used, even when the other drawbacks are not a concern. The reasons for this are several physical limitations:- The current density is low, because it relies on space charge of electrons in vacuum. Whereas semiconductors can carry vast current densities due to charge balance within the crystal.- Voltage is high, because even with carefully controlled mechanical tolerances, the spacings are relatively wide, and therefore the electric fields cannot be very strong, and cannot induce much current flow until much higher voltages. Typically the "knee" voltage of a pentode is in the 20-100V range (compare to ~Vgs for MOSFETs, or 0.1-5V for BJTs). (A semiconductor analogy might be using aCdS photocell as a MOSFET: due to the thick layer of passivation on the surface, quite a high voltage is necessary to induce conduction.)- As a result, the impedance is relatively high, typically not below 2kohms, and frequently over 10k for small signal types. This is well in excess of the impedance of free space, so transformers or matching circuits are required to match these devices to common transmission line structures (like 300 ohm twin lead). Needless to say, any dielectric-filled structure (like 50 ohm coax, or 50-150 ohm traces on a controlled-impedance PCB) is essentially hopeless with direct drive.And since impedance matching is now a concern, electrode size (capacitance, inductance) is also a concern, and it's really not looking good for our old friend, the tube.In contrast, semiconductors typically do very well driving the impedances of dielectric-loaded structures, and thus the bandwidth is practically unlimited by outward physics.One peculiar difference is how effective bandwidth plays out. BJTs are limited first by junction capacitance, and second (and ultimately) by recombination time (fT is measured by forcing AC output voltage to zero, so it's as purely as possible the current gain of the transistor, no capacitive loading included). JFETs and MOSFETs aren't limited by this, but because their structures are somewhat ponderous in design (interdigitated structures with high surface area), they exhibit distributed resistance and capacitance which has a similar effect. They're also limited by the drift velocity of current through the semiconductor, a thermally mediated phenomenon characteristic of the semiconductor (whereas the electrons in vacuum of a tube are completely and utterly unhindered).The result is, you can have a BJT circuit that's doing 100MHz, and that's all it's ever going to do. It can do it from DC to 100MHz solid, but it's not doing any more.You can have a tube circuit that's wideband, DC to 10MHz, and that's all it's ever going to do. That is simultaneously oscillating at 400MHz, because you're dumb and forgot grid damping resistors!With tubes, there's kind of three operating regions: wideband / resistive; tuned; and tuned high frequency.The wideband region is basically limited by load resistance and electrode capacitance (give or take if you can neutralize that capacitance some way, like with Tektronix' favorite tee coils and distributed amplifiers).The tuned region is as well, but because the electrode capacitance forms part or all of the tuned circuit, you get the same band *width*, but shifted up to the resonant frequency. So the percentage bandwidth drops as frequency rises, but the absolute bandwidth remains fairly constant. So a 10MHz wideband amp might be very easily rewired for operation at 20-30MHz or 90-100MHz.The "HF" range is limited by electrode inductances and capacitances, so that operation becomes more and more difficult at higher frequencies (into the 100s of MHz). You need neutralization on pentodes (which are otherwise exquisitely well shielded, i.e., s21 is very small at low frequencies), and grounded grid operation for triodes (which may still need neutralization, even in GG). Operation might be uncontrollable above the first or second electrode resonant frequencies (i.e., 500MHz+ for most types). Physics also, finally, steps in to put a limit on performance up here: the electron stream isn't moving fast enough (and consistently so) to remain coherent for the rate it's being switched at, and it smears into a blob (similar to the FET's resistance causing current flow to slur together).The magic isn't over, though. After the war, devices were designed for microwave operation. Planar triodes, where the cathode is a flat plane, the grid is a mesh screen, and the plate is nearby, are designed to operate within resonant cavities, and extend up to several GHz. The close spacing (short drift region) is what does it. Extending the concept of a distributed amplifier, the traveling wave tube (TWT, or occasionally abbreviated Traveling Wave Amplifier Tube) uses no grid structure at all, but converts electron beam energy into electromagnetic gain by shooting the beam down a spiral. TWTs are still flown in space, to this day (actually they may finally be done, I don't know all that much about aerospace), due to their great reliability, noise figure, radiation hardness and proven record (since, after all, not one damn thing makes it into space without one hell of a qualification procedure and paper trail).To this day, magnetrons can't be beat for cheap, efficient and powerful microwave oscillation. Probably not used much for communications, but I understand they're easy to find in the 2.45GHz band for some reason.Klystrons (which can be imagined as a more flexible, usually less efficient, variant of the magnetron) are also still around, but mostly limited to scientific and medical applications where controllable microwave power is needed (i.e., particle accelerators; if you ever have a product irradiated by ~4MeV electrons, they were probably propelled by a klystron).Now after having covered all of that...What's interesting about the present subject is, they have the potential to give far better characteristics than historical parts did. Example: a 6CW4nuvistorhas typical Gm = 10mS at 10mA plate current and 100V plate voltage. It's very, very much like a typical JFET, but -- like I said, about ten times the plate voltage. If you don't mind the extra plate voltage (say, as a cathode follower: Tek and HP used them for instrument front ends for more than a few years), the bandwidth is excellent (100s MHz). With still closer electrode spacings, and contributions from modern materials science, manufacturing methods, fabrication and stereolithography, they could probably bring that up to more like 20mS and 50V -- no, still not competitive with transistors by a long shot, but it's still an interesting product. Their product might even have a legitimate (read: technological) advantage over some semiconductors, like the poor availability of anything over 175C rating.Tim

author: coppice
author_rank: Super Contributor
timestamp: January 23, 2015, 09:17:35 am
content: Quote from: T3sl4co1l on January 23, 2015, 09:04:41 amMost people think of valves as things which wear out because of the heater. The 15 year continuous use life TWTs in orbit, with a near zero failure rate, shows the heater issue can be overcome. A soft vacuum is the second commonest cause of valve failures, but in orbit you wouldn't even know if the vacuum seal has failed.When I worked with large TWTs (The orbital ones are a few watts. The ones I worked with produced 15MW pulses) the tubes were rebuilt periodically, replacing the heaters.

author: dannyf
author_rank: Super Contributor
timestamp: January 23, 2015, 12:42:44 pm
content: Using VFD as tubes for linear applications isn't new and is reasonably well known.

author: macboy
author_rank: Super Contributor
timestamp: January 23, 2015, 03:28:41 pm
content: Quote from: coppice on January 23, 2015, 02:43:32 amHah, Japanese companies seemingly do everything. I have a Kyocera mobile phone (in a junk box, just to be clear) and a Kyocera ceramic blade kitchen knife. Yes, definitely the same company, not just the same name. You can also buy ICs, consumer electronics, kitchen applicances, the world's most infamous.... personal massager, and of course, heavy equipment like dump trucks and excavators, all made by Hitachi.

author: wraper
author_rank: Unknown
timestamp: January 23, 2015, 03:40:19 pm
content: Quote from: macboy on January 23, 2015, 03:28:41 pmOr just plain steel made by Hitachi.Or Mitsubishi: DVD discs, chemicals, ICs, air conditioners, cars, airplanes, rockets, satellites, nuclear fuel, nuclear reactors

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 23, 2015, 04:53:43 pm
content: Noritake is quite innovative. Some 10 years ago or so, they made a VFD with the fluorescent anode directly on the drive chips. It was huge bright because no multiplexing needed. Disadvantage was limited character size due to limited chip size. However it never came commercial available.And about Kyocera. They are also the main manufacturer world wide, of paper wide thermal print heads as used in cash desks and credit card printers. I wouldn't be surprised if the print head in the Canon "Selphy" photo printer is also from Kyocera.

author: elgonzo
author_rank: Unknown
timestamp: January 23, 2015, 04:58:01 pm
content: Quote from: macboy on January 23, 2015, 03:28:41 pmHmm, this coincidentally makes me think how "Siemens" would be pronounced in Japanese

author: free_electron
author_rank: Super Contributor
timestamp: January 23, 2015, 05:39:09 pm
content: Quote from: T3sl4co1l on January 23, 2015, 09:04:41 ami still need to see the first 45nM tube ... let alone the first sub millimeter tube ...i wonder if there is a moores law for tubes ...have you seen my quad core PIV ? its 9 footballfields and suffers from china syndrome when powered up ....

author: Howardlong
author_rank: Super Contributor
timestamp: January 23, 2015, 06:00:37 pm
content: Quote from: coppice on January 23, 2015, 09:17:35 amTypically in space the TWT is treated like a commodity, we use a pool of them, with enough for a number of spares upon launch, ready for use as required. There's an RF switching matrix to pull in the good ones as required. Just another engineering approach, but redundancy is key. Last time I checked it still wasn't cost effective to send up a dude with a Rigol and a soldering iron.Edit: while I am sure there are solid state options at the power required, it's a brave soul who risks a commercial launch with hardware that has limited heritage. Just the thermal engineering for solid state at that power scares me, fans don't work too well in that environment...

author: coppice
author_rank: Super Contributor
timestamp: January 23, 2015, 06:01:43 pm
content: Quote from: wraper on January 23, 2015, 03:40:19 pmThey are also a large bank. I wonder how tough they are about giving themselves finance?

author: wraper
author_rank: Unknown
timestamp: January 23, 2015, 09:20:55 pm
content: Quote from: elgonzo on January 23, 2015, 04:58:01 pmForum do not support katakana, so here is the link. shii(long i)-me-n-suhttp://ja.wikipedia.org/wiki/%E3%82%B7%E3%83%BC%E3%83%A1%E3%83%B3%E3%82%B9

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 23, 2015, 09:56:28 pm
content: Quote from: free_electron on January 23, 2015, 05:39:09 pmThey should work down to the scale of semiconductors, limited by the same problems, i.e. leakage due to tunneling, capacitive loading due to dielectric constant, that sort of thing. The current density is a big drawback, and I don't think that can be fixed (otherwise you're making at least a plasma triode, or... just a plain old transistor!).MEMS is definitely able to fabricate such beasties, it's just that no one's doing it. Maybe the random research project here and there, by PhDs who don't know a damn thing about process optimization and all that. So you're basically never going to see anything better than the old bottle-state parts.Tim

author: Rory
author_rank: Frequent Contributor
timestamp: January 24, 2015, 12:26:23 am
content: Quote from: T3sl4co1l on January 23, 2015, 09:56:28 pmVacuum channel transistor:http://spectrum.ieee.org/semiconductors/devices/introducing-the-vacuum-transistor-a-device-made-of-nothing

author: calexanian
author_rank: Super Contributor
timestamp: January 24, 2015, 06:56:50 am
content: This is nothing new.. This type of approach was investigated in the late 50's through the 60's for speeding up television production and mounting tubes directly on the PCB's. Transistors came along so fast there was no point to doing it and it was just so much cheaper to build using the traditional method the idea was scrapped. I have seen many different versions of this throughout my travels and none have ever been successful commercially. I suspect this one will go the same way. I have been working on a photo lithographic chemical etching process for making very precision little tubes for esoteric applications. High Rad/ X-Ray environment and possibly very high frequency stuff. But I am only doing it as an exercise in engineering. Its a solution looking for a problem so to speak.This on the other hand looks like a VFD department of a large company having the internal discussion, what else can we do to keep this place going.

author: SeanB
author_rank: Super Contributor
timestamp: January 24, 2015, 07:59:05 am
content: The nice thing is a VFD is a very close tolerance unit, and it is mostly automated manufacture, so the variation from unit to unit should be very small, and the precision should give very good characteristics, along with a simple package and a very good well made seal that is very reliable. Now all they need to do is develop a flat plate indirectly heated cathode for the units, or simply make a back tub with the indirectly heated cathode in it with separate cathodes so you can do a pentode unit with 4 matched devices in a single package. All it needs is to handle 2W anode dissipation for the whole device to be a good high impedance high voltage front end.