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

We need this type of thing done in the classrooms

[Jailbrekr]

While vacumn tubes are strictly in the realm of hobbyists and zealous audiophiles, nevertheless it is important for teens and young adults to understand where the electronics industry started from. They're already made to study what can argueably be considered useless information, so why not study something that is cool and informative as well? Think of it as shop class for nerds.

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

[Clueless Moron]

You can learn a hell of a lot from vacuum tubes! They are far easier to understand than transistors.

There's a reason why they're called "valves" in the UK. It's like a valve controlling a powerful stream of water; a small change on the valve leads to a very large change of current. That change in current can, in turn, control a much bigger valve that controls an even larger current.

In this case, the "valve" is a control grid (that spiral thing) surrounding the cathode (the thin hot wire in the middle). The big cylinder is the "plate". The cathode itself has a cloud of electrons around it (because it's hot), and a small signal on the grid controls how much of that can scoot across to the plate (which is positively charged due to a power supply putting a strong positive voltage on it). So a weak sine wave signal on the plate will lead to a big sine wave current from the plate.

There, now you know the basics of amplification (although I skipped some details). I couldn't have done it by describing a BJT (transistor), because they're far weirder.