Component of the Month: Op Amps

Component of the Month: Op Amps

Each month this year, we’re exploring a different electronic component, delving into what it is, how it works, and how you use it in projects. Last month we covered resistors, and before that we looked at batteries. This month we examine operational amplifiers, often called op amps.

Makezine_COTM_OpAmp-BadgeAn op amp is an electronic component used to amplify, filter, and control analog signals. It can be used to increase the power of a signal, taking energy from the power supply and controlling the output to match the input signal, only with a larger amplitude.

Op amps are known as “operational” amplifiers because they were originally designed to perform mathematical functions. They were invented in 1941 and quickly found a use during World War II performing trigonometric calculations to direct artillery barrages.

The way it works is that the amp takes the difference between the two inputs (V+ and V- on the diagram) and multiplies it by a lot (10,000 or more) with other circuitry like resistors and capacitors being used control the output. This brings up the two golden rules of op-amps:

500px-Op-amp_symbol.svgI. The output attempts to do whatever is necessary to make the voltage difference between the inputs zero.

II. The inputs draw no current.

While these laws aren’t inviolable, they serve as a good way of analyzing circuits. Despite that, op amps are pretty tricky for neophytes to figure out, but this video describes it as neatly and understandably as one could hope for:

YouTube player

I hope this helps you understand op amps a little more! In May we’ll be exploring op amps, and hopefully you’ll learn even more.

[photo credit: Adafruit]

6 thoughts on “Component of the Month: Op Amps

  1. Christopher Favreau says:

    Nice article. I find this app note from TI with a large amount of OpAmp circuits and their calculations very handy.

  2. Keith Rome says:

    Oh, finally a component of the month with some heft :)

  3. Jim Ruby says:

    Christopher: Looks like TI changed it’s documentation already, but I was able to hunt down the new one at Thanks for the reference, it’s a very useful document.

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My interests include writing, electronics, RPGs, scifi, hackers & hackerspaces, 3D printing, building sets & toys. @johnbaichtal

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