Vacuum Tubes

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What is a Tube?1

  • A device used to amplify currents and signals.
  • Also known as electron tubes.

How do tubes work?5

  • A cathode, or negatively charged conductor, is heated to “boil off” electrons.
  • The electrons fire towards a plate which is positively charged creating a current.
  • By altering the current in the plate, you are in turn increasing the voltage. Therefore, amplifying.

Tube History

  • First version was a diode invented in 1904.1
  • Originally used to detect weak radio waves.1
  • Made radar possible.4
  • Guitar Amplifiers.1
  • Radios and jukeboxes.
  • CRT (cathode ray tube) monitors functioned using tube technology. This is why the television was called the tube for so long.
  • John Randall and Harry Boot had invented the cavity magnetron, by improving on similar designs of the past.9
  • Able to generate strong microwaves which resulted in a massive increase in the ability of allied radar.
  • This technology is how a microwave oven works.
  • See reference 9 for the incredible story of Britain sharing this tech with the us. I could make an entire episode about the history surrounding it.

How are tubes used today?

  • One of the more interesting uses of tubes is in coms satellites due to their reliability and efficiency.4
  • While solid state alternatives have taken over, many audiophiles and musicians prefer microphones and amplifiers that run on tubes.
  • Tube technology is considered to be warmer and more spacious, or fuller, sound.

Enter: Transistors

  • Either an amplifier or a switch.6
  • Works similar to a tube but on a much smaller physical scale. Around 500 transistors in a chip the size of your fingernail.6
  • The most important invention that led to personal computers.7


  • Transistors and semi-conductors can only get so much smaller using current methods.
  • Some suggestions include using Nano-sized “strings” of transistors or memory in a 3-dimensional pattern rather than 2-dimensional.