Hand-Made Vacuum Tubes

djmoore writes "Over at Make Magazine, watch this video of a French amateur radio operator making and testing his own vacuum tubes. It looks like he built much of his own equipment as well. The Make poster notes: 'I love the ease with which he performs these rather high-end skills (like glass forming), the gestural flourishes (like it's hand magic), and the Zelig-esque soundtrack.'"

Comments

Re:"French amateur radio operator"

[Anonymous Coward]

Neither Make nor Slashdot have the basic decency to name the man: Claude Paillard.

What is it with acting like foreign nationals are some sort of trained monkey? C'mon folks.

Anyway, here's a direct link to his site so you can skip the non-article at Make. Site includes much information (use the fish as needed), the streaming dailymotion vid, and a download link for those who can't see streams. Enjoy.
http://paillard.claude.free.fr/

Thanks Claude! That rocks.

Re:reason

[ptorrone]

the article is over 5+ pages with a lot of details on making something (http://www.make-digital.com/make/vol04/?pg=124&pm=2&u1=friend) - while the author didn't post the data sheets he used an analogy and explained it to do the project, that's what most folks want, at least for this type of article - for more details we usually the companion pages on MAKE, the forums and additional articles we refer to. part of a project like this is a little reverse engineering from an amateur who is ok with exploring things too - regardless, sorry we didn't live up to your expectations.

He not only made the tube,

[Toinou]

he also made all the necessary equipment, like vacuum pump. If you are interested in tubes, he says the "musée des arts et métiers" is a reference. This is an engeneering museum in Paris, which has an incredible collection. When I go there, I stay for hours. Do not mistake it with the science, the nature science, or the technology museum (which are also quite interesting).

Glass/Metal seals...

[Ellis D. Tripp]

If you look closely at the wires he is sealing into the glass "press", you will see a short reddish-brown section. This is most likely "dumet", or copper coated nickel/iron. This material is specially designed to have the same coefficient of thermal expansion as glass, and was used as the sealing material in most receiving tubes. The copper coating forms an oxide layer that dissolves into the glass, creating a vacuum-tight seal.

Before the development of dumet, kovar, and other specialized alloys, the seals in very early tubes were made using platinum wire. Cost considerations brought this to a quick end, as soon as cheaper suitable materials were developed.

The electrodes in later tubes were often coated with various materials to aid heat dissipation or reduce secondary electron emission. Early tubes that were similar in construction to what is being made here generally used plain metal grids and plates.

Most tubes contained a "getter" made of barium or other reactive metal, to adsorb any gas molecules which survived initial pumpdown, or which were liberated from the internal elements during operation.

Re:We need this type of thing done in the classroo

[Anonymous Coward]

The silvering has nothing to do with radiation. It is a thin coating of reactive metal to take up any oxygen left in the tube after it has been sealed. If you ever find an old tube where the silver patch has gone white, it is gassy and will not work properly. (It may work to some degree but is also likely to have a strange glow from ionising the gas. Depends how much gas has leaked in.)

You do get X-rays from tubes working at high voltages, but they are of pretty low energy in typical applications and probably don't make it out through the glass. TV tubes use leaded glass to reduce the X-radiation.

Re:We need this type of thing done in the classroo

[DeathElk]

The purpose of using vacuum tubes in a guitar amp is for the overdrive characteristics. When overdriven, solid state amplification circuitry clips the waveform to the voltage rails, resulting in a harsh sounding distortion due to the dissonant overtones.

A tube amp driven to distortion compresses the waveform rather than hard clipping. This results in a waveform rich in harmonic overtones - the classic distorted guitar sound.

Any person who is not tone deaf can tell the difference between solid state distortion and tube distortion. Please don't compare the basic principles of rock guitar with overpriced audiophile folly.

State of the Art

[localroger]

Limping through the writeup with what's left of my high school French I get the idea that he's not just making homemade tubes, he's duplicating a particular class of historic tubes which were common around WWI. He's using authentic techniques. These tubes were handmade at great expense because they were used for maritime communication where price was no object, and modern standards of longetivity didn't apply; if such a tube lasted 500 hours it was doing great. Also, some of those tubes had soft vacuum so an imperfect seal wasn't such a big deal.

I do have to say this is one of the most impressive projects of its type I've ever seen; it's clearly a labor of both love and skill.

Semiconductors never could have been made without

[Ellis D. Tripp]

vacuum tubes.

Once you get beyond the crude PN junction diode (like a galena crystal), making transistors and such requires ridiculously pure germanium and/or silicon. These materials are purified by a process called "zone refining" which uses induction heating to melt the semiconductor materials at incredibly high temperatures. Induction heating in turn requires many kilowatts of radio frequency power, which is exactly the type of application where vacuum tubes are still widely used even today.