Seektronics

  555 Timer   If you've played with electronic circuits, odds are you know about the 555 timer integrated circuit, said to be the world's best-selling integrated circuit, with billions sold. Designed by analog IC wizard Hans Camenzind, the 555 has been called one of the greatest chips of all time.   Tediously sanding the epoxy package to expose the chip (below) and identifying the chip as a 555 timer. signets released the 555 timer in mid-1972, and the chip below has a date code of January 1973 (7304), so it must be one of the earliest 555 timers. Oddly enough, it is not labeled as a 555, so it may be a prototype or internal version. I took detailed photos of the die, which are discussed in this blog post.     A brief description   The 555 timer has hundreds of applications, from timers or latches to anything from voltage controlled oscillator or modulator operation. The following diagram illustrates how the 555 timer works as a simple oscillator. Inside the 555 chip, three res