Before the invention of transistors and later "integrated circuits," an electrical circuit, consisting of vacuum tubes (also called "valves") and other components, was devised in the early 1940s to perform the function of an operational amplifier. With the invention of the transistor in 1947, replacing tubes as the active component in circuits, operational amplifiers became much smaller, ran cooler and required less power to work. Integrated circuits became the next generation of electronic components, where many transistors, capacitors, resistors and interconnecting wiring were placed in one small, convenient package. In 1961, the first integrated circuit (IC) op amps came on the market, with the low cost of only a few dollars.
Op amps, short for "operational amplifiers," are electronic circuits that have a wide variety of uses in electronic equipment. Today, op amps come in small packages about the size of a fingernail. One op amp can take the place of as many as 20 discrete electronic components. These convenient devices are used by electrical engineers as basic compact components in the design of a diverse array of electronic devices and appliances.
Operational Amplifiers Used In The 1940s
With the ability to perform addition and subtraction computations, operational amplifier circuits with vacuum tubes were used in early analog computers. During the war years in the 1940s, operational amplifiers were part of the design of the M9 artillery directory, which worked in conjunction with a radar system to improve the accuracy of shots.
General Uses Today
It's difficult to find a piece of electronic gear today that doesn't utilize an op amp somewhere in its circuitry. Op amps are used in audio products, from mixing boards to "boom boxes" and high quality home stereo systems. Guitar "stompbox" effects foot pedals use op amps for various audio signal processing. A new generation of op amps finds them being used in precision instruments, communication devices and medical equipment.
As for design engineers, op amps are used to perform many internal functions as part of an appliance or piece of equipment. In power supplies they are used to provide a steady voltage output under fluctuating load conditions. Their high input impedance makes them desirable for use in electrical and laboratory test equipment. Circuits that require inductors have always had the disadvantage of requiring components made up of large coils of wire. Coils are bulky and susceptible to picking up other electromagnetic noise from associated circuitry. Op amp circuits can be created to simulate inductors, avoiding these problems. When used to perform filtering tasks, op amps can be used in EQ (equalization) applications for audio processing and as noise filters to remove hum and hiss from remote audio lines. Analog-to-digital converters (and the reverse), oscillators, waveform generators, buffers, peak detectors, differential amplifiers and other functions use op amps for consumer and industrial applications.