In the storied history of electronics, very few components have managed to command the iconic status the 555 timer has enjoyed. Since its emergence in the early 1970s, this versatile integrated circuit (IC) has become a cornerstone of hobbyist and professional projects alike.
Bearing in mind how long it has been around for, it might surprise many newcomers to learn that the 555 timer remains a go-to solution for the creation of precise timing circuits.
Yes, that’s right: thanks to its combination of robustness, low cost, and straightforward external resistor-capacitor (RC) control, the 555 timer still appears in breadboard projects, classroom laboratories, and simple product designs in the 2020s.
An Introduction to the 555 Timer
Before we delve into the history of this remarkable component, it is worth us setting out the essentials of what the 555 timer IC has long been, and what it continues to be today.
The 555 timer is a small, inexpensive IC that is able to generate accurate time delays or oscillations. It is housed in an eight-pin package and can operate in three main modes:
- Monostable mode, which produces a single pulse of a set duration when triggered. It can be used for such applications as timed door locks, buzzers, and LEDs.
- Astable mode, which generates a continuous square wave, due to the output continuously oscillating between high and low. This mode frequently sees use for applications like LED flashers, tone generators, and clock signal generation.
- Bistable mode, which acts as a basic flip-flop, switching between two states. This makes bistable mode useful for applications such as electronic locks and simple on/off switches for lights or alarms.
The ability of the 555 timer to perform functions like these with minimal external components – typically nothing more than a few resistors and capacitors – has helped make it a staple in electronics for more than five decades.
How Did The 555 Timer Come About – And Why Is It So Important?
Working under contract to American electronics manufacturer Signetics at the time, it was the late engineer Hans Camenzind (1934-2012) who designed the 555 timer IC in 1971.
The design of the 555 timer packed comparators, a flip-flop, a discharge transistor, and a simple resistor divider into a single DIP-8 package. This single, inexpensive chip represented quite the upgrade on the bulky discrete timing circuits that had been used until then.
In the years prior to the 555 timer’s invention, the creation of precise timing circuits often necessitated complex setups with multiple transistors, resistors, and capacitors. These were expensive to create, as well as susceptible to error.
It perhaps shouldn’t be so surprising in retrospect, then, that the 555 timer attracted plenty of admirers after its launch, and went on to sell in big numbers.
In the shape of the 555 timer IC, the world finally had a genuinely affordable, reliable, and compact solution for a wide range of timing, pulse generation, and oscillation applications.
Sure enough, the 555 IC timer duly found its way into an abundance of applications, ranging from the pulsing lights on 1980s arcade machines, right through to the timing circuits in early home computers, such as the Sinclair ZX Spectrum.
What Is the Situation of the 555 Timer IC Today?
Even in our present era that has seen the emergence of microcontrollers like the Arduino and Raspberry Pi, the 555 timer has managed to retain an impressive degree of relevance.
This success story is attributable to the distinctive combination of ease of use, accessibility, simplicity, versatility, and educational value that has made this component a force to be reckoned with since its first release.
Even if you are a “mere” hobbyist, you can get started yourself with 555 timer-based projects with relative ease. Gather some components like the 555 timer itself and some resistors, capacitors, and a breadboard, and bookmark a 555 timer calculator like the one on the RS website, and you will soon be well-placed to begin building a simple circuit.
For projects ranging from simple flashers to complex control circuits, the 555 timer remains a testament to the ingenuity of electronics design. Long may this humble, but remarkable device reign!
