The December 2022 issue of IEEE Spectrum is here!

Close bar

Chip Hall of Fame: Signetics NE555

A humble timer chip that became the Swiss Army knife of countless circuits

2 min read
Photo of Signetics NE555 chip
Hans Camenzind

chipPhoto: Hans Camenzind

NE555

Manufacturer: Signetics

Category: Logic

Year: 1971

It was the summer of 1970, and chip designer Hans Camenzind was working as a consultant to Signetics, a Silicon Valley semiconductor firm. The economy was tanking. He was making less than US $15,000 a year and had a wife and four children at home. He really needed to invent something good.

And so he did. One of the greatest chips of all time, in fact. The 555 was a simple-to-use IC that could function as a timer or an oscillator. Still popular today, the chip was a smash hit, winding up in kitchen appliances, toys, spacecraft, and a few thousand other things.

“And it almost didn’t get made,” recalled Camenzind for IEEE Spectrum a few years before he died in 2012.

The idea for the 555 came to him when he was working on a circuit called a phase-locked loop. With some modifications, the circuit could work as a simple timer: You’d trigger it and it would run for a certain period. Simple as it may sound, there was nothing like that around.

At first, Signetics’ engineering department rejected the idea. The company was already selling components that customers could combine to make timers. That could have been the end of it. But Camenzind insisted. He went to Art Fury, Signetics’ marketing manager. Fury liked it.

Camenzind spent nearly a year testing breadboard prototypes, drawing the circuit components on paper, and cutting sheets of Rubylith masking film. “It was all done by hand, no computer,” he says. His final design had 23 transistors, 16 resistors, and 2 diodes.

Photo: Mark Richards/Computer History Museum

One of the keys to the 555’s success was that designers managed to get the circuit down to requiring just eight pins, which meant a small and compact package as seen in this early version.

When the 555 hit the market in 1971, it was a sensation. In 1975 Signetics was absorbed by Philips Semiconductors, now NXP, which says that many billions have been sold. Engineers still use the 555 to create useful electronic modules as well as less useful things, like “Knight Rider”–style lights for car grilles. And for hard-core 555 fans, you can even build a drop-in “macrocircuit” replica kit, assembled out of discrete transistors.

The Conversation (0)

How Ted Hoff Invented the First Microprocessor

Hoff thought designing 12 custom chips for a calculator was crazy, so he created the Intel 4004

14 min read
Horizontal
How Ted Hoff Invented the First Microprocessor
DarkGray

The rays of the rising sun have barely reached the foothills of Silicon Valley, but Marcian E. (Ted) Hoff Jr. is already up to his elbows in electronic parts, digging through stacks of dusty circuit boards. This is the monthly flea market at Foothill College, and he rarely misses it.

Ted Hoff is part of electronics industry legend. While a research manager at Intel Corp., then based in Mountain View, he realized that silicon technology had advanced to the point that, with careful engineering, a complete central processor could fit on a chip. Teaming up with Stanley Mazor and Federico Faggin, he created the first commercial microprocessor, the Intel 4004.

Keep Reading ↓Show less