The Vacuum Tube

The vacuum tube was the first device that could amplify and switch electrical signals, and it built the modern world’s first electronic age. From Fleming’s 1904 diode and De Forest’s 1906 triode came radio, long-distance telephony, television, radar, and the earliest computers. ENIAC ran on some 18,000 of them, glowing hot and burning out so often the machine failed every couple of days. Tubes were bulky, fragile, and power-hungry. The transistor, invented at Bell Labs in 1947, did the same work in a cool, tiny, durable package, and by the early 1960s had replaced tubes nearly everywhere except cherished audio gear.