It goes by many names, among them electron valve, thermionic valve, triode, glassfet and, the best, firebottle. It’s the vacuum tube: a melding of form and function, of beauty and truth. And it began as a mystery.
In 1882, William Hammer, an engineer working in Thomas Edison’s lab, detected an electric current streaming from a heated cathode in a glass tube from which the atmosphere had been sucked. This was before anyone knew the word electron.
Then in 1904, the English scientist John Ambrose Fleming invented the Fleming valve, a diode containing a cathode and an anode capable of detecting radio signals. In 1907, the vacuum tube reached maturity when Lee De Forest patented the audion tube, a triode consisting of an anode, a cathode and, crucially, a wire mesh grid, allowing the vacuum tube to function as an amplifier, modulator and switch.
The tube gave us radio. It gave us television. It gave us the ENIAC computer that used 17,468 tubes.
Today, solid state dominates but microwave technology still relies on the tube’s ability to handle very high voltages. Audiophiles swear that tubes produce deeper, richer sounds than any transistor. True or not, nobody ever huddled up to a transistor.
