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Return of the Vacuum Tube
sciencehabit writes "Peer inside an antique radio and you'll find what look like small light bulbs. They're actually vacuum tubes — the predecessors of the silicon transistor. Vacuum tubes went the way of the dinosaurs in the 1960s, but researchers have now brought them back to life, creating a nano-sized version that's faster and hardier than the transistor (abstract). It's even able to survive the harsh radiation of outer space."
...to the phrase "a series of tubes."
These are still widely used in some of the best amps out there.
Almost every TV broadcast transmitter and most FM radio broadcast transmitters still use vacuum tubes for the high power output stages. Every microwave oven uses a vacuum tube to produce the microwaves. Most radar transmitters use vacuum tubes for the output stages, and often for signal generation too. The fact is that semiconductors have simply not been able to catch up to vacuum tubes for high power applications at UHF frequencies and above. 1960's technology still reigns supreme.
I am a geek attorney, but not your geek attorney unless you've already retained me. This is not legal advice.
Keep seeing all these whippersnappers nowadays wearing the same clothes I wore years ago.
You should have thought of that before you donated them.
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Actually an open heater was NOT the way most tubes died. The coating on the cathode that emits electrons when heated gradually decays and emission drops off to the point that the tubes transconductance is too low for it to operate. But the heater rarely burns out, at least not in indirectly heated tubes. Another way they die is that air gradually leaks in and the vacuum becomes too poor. The silver flashing on the side of the tube will then turn a milky white as the chemical "getter" that absorbs air has absorbed all that it can. Once the getter coating is depleted the tube will become gassy. A tube can also die from shorts when closely spaced elements break loose from vibration and touch. Over heating will soften the elements and cause the same effect. Tubes can handle a much higher percent of overload than solid state devices however. Tubes computers were never faster than solid state ones even if the tubes themselves were faster. Because of their size the total wiring in a tube computer is much longer than in a solid state system. In transistors it is the "holes" in the crystal structure that "move" and the speed of light in silicon is lower than in a vacuum for electromagnetic waves. Still these waves have less distance to propergate in an IC than a bunch of interconnnected tubes. Finally note the description of this new tube technology, it is really a "vacuum state" IC. I always wondered when nanotechnology would be applied to thermionic "valves" (as they say across the "pond").
When Viktor Belenko defected to Japan with a MiG-25 fighter jet in 1976 (state of the art Russian aircraft back then, meant to counter our F-15) it was discovered that most of the electronics onboard the aircraft were built with micro-miniature vacuum tubes! The reason being that the fighter jet was designed for presumably nuclear war situations, and the Russians wanted to ensure that EMPs from nuclear explosions would not permanently damage the electronics, so the aircraft could still fly and fight even after exposure to any nearby nuclear explosions that were still distant enough to not physically destroy the aircraft.