EEVblog 1746 - The 555 is 55 Years Old!

The 555 timer, a classic electronic chip, celebrates its 55th anniversary. Developed in 1971 by Hans Camenzind as a contractor for Signetics, the initial nine-pin design was refined into the familiar eight-pin DIP version by October 1971. Camenzind, who was paid a pittance, conceived the timer chip from a PLL circuit he was working on. Despite initial management skepticism, marketing saw its potential. Signetics notably didn't patent the 555, leading to a dozen suppliers by 1972, which propelled its widespread adoption. Art Fury, Signetics' marketing manager, named it "555," likely referencing the three 5k resistors in its internal circuit. The chip quickly became an industry standard, advertised as having "a thousand and one uses" even in its release year. Its design remains largely unchanged, with a CMOS variant addressing some limitations. The 555 timer continues to sell in vast quantities and is used in countless applications, including space-rated versions.