Voltage Follower - Operational Amplifier | Basic Circuits | Electronics Tutorials

Operational amplifiers, or op-amps, have a variety of popular configurations but one of the most often used is as a voltage follower. In this video, Josh goes over the concept behind a voltage follower, where and why you'd need it, and does a practical example showing how it affects the output voltage of a high-impedance source.

Parts of the video:
0:00 Introduction
0:36 What's the point of a voltage follower?
0:54 High- versus low-impedance outputs
3:47 Simulating a high-impedance output
4:38 Setting up the op-amp voltage follower
6:01 Trade-offs
8:21 The toast will never pop up

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[Jnglfvr]

At 5:28 you have it backwards. The output should provide negative feedback into the inverting terminal and the 47K ohm resistor should be fed into the non-inverting terminal. The circuit will not work the way you describe. It did work, however, because you mis-identified the inverting and non-inverting terminals and actually connected them opposite to your narrative. Take a look at the circuit diagram at 3:28.

[brianm]

The WHY explanation was exactly what I needed! Please keep telling us the why in all of your videos.

[notanymore]

Thank you!
I’ve been struggling to understand what applications op amps in general are used for and this totally made sense.

[bothwellchingombe]

I’m glad I found this channel.
Makes understanding electronics much easier.

Please keep up the good works my good Sir.

[JohnJohn-dcid]

Now that's a great explanation 🎉🎉

[ovi_]

Wow....what a great resolve. I was trying to understand someone's circuit. He made a little circuit using a dual op-amp (LM358) to amplify a small signal needed for an analog movement in an old radio. By analog movement I mean the signal strength indicator (the meter. I believe it must be a baby size micro-amp-meter. Possibly 50-to-150uAmps). So he used the 2 op-amps in a series configuration but didn't know that the very first op-am was configured as a voltage follower (so the existing signal could be amplified without unbalancing the signal itself. Wow..this is what I needed to snow. I have subscribed right away!. Thank you. PS: I'm just beginning to understand the world of OP-amps. They are so versatile is unreal. I hope to master it one day (fingers crossed) :)))

[colyjiang]

Thanks for these videos, they really have improved my knowledge of circuits. You also consistently answer questions in the comments, making sure your viewers understand the concepts, which is something I haven't seen other youtubers do. Keep up with the great work.

[Mischiefcity]

Best explanation I've found by far! Thanks, seriously appreciate it.

[crystalmacau]

Thanks for the explanation, i was wondering what high impedance meant and now i know, and what that voltage buffer is good for!

[edgeeffect]

I've just this minute, finally got my head around what high/low impedance really means... Great stuff... thanks.
Be interesting to see what it'd look like to build a voltage follower using BJTs or FETs.

[zetaconvex]

Thanks Josh. It's worth pointing out that the output draws current from the power supply rather than the input source itself. So there's no magic involved.

Something that I struggle with - and something that is rarely mentioned - is what to do about powering the opamp. This is to do with how close the input voltage can get to the power rails. It's a subject that tutorials skimp over and taken as a given, but can leave nebies like me puzzled as to why I'm not getting the output I expect.

[lad]

I am binge watching this video's, they are awesome, better than my classes

[flaviodanca]

Few words but a lot of meaning. Nice job.

[maovichet]

Great i like electronic so much, thank for your sharing.

[JonDeth]

I'm assuming that op amp has sentimental value considering when it was purchased. My first serious dual op amp circuit turned out to become a high gain distortion pedal with soft clipping germanium diodes, and soon I will retire it to showcase more like a trophy.
When I "designed" it, I really had no scientific understanding and relied on tutorial basics of setting gain, RC filters and diodes on the feedback path to produce soft clipping.

[wysskey]

I use this circuit often to feed remote sensors . If you stick a blocking diode into the supply voltage of the op amp you get non destructive short circuit protection as well as reverse battery protection without damage to the op-amp. ?¿

[_yourNameHere__]

Besides the mistake in the pinned comment, I think that RL is connected to Vcc rather than to ground. Shouldn't that be connected to Ground?
Thank you for the this series. It's pretty helpful.

[henrysavioezeorah]

I love your tutorials! ❤
I wish to know if this configuration can be applied in any way to build an optical transmitter. Pls be of help 🤝

[adrianzayas]

Hi, thank you for your clarifications. I have a question about the impedance of the voltage follower. If the Vi=Vo in this type of op-amp, would you say that the impedance of the op-amp is 0 or 1? If there is no Rf would you consider (Rf/Ri)= 0 or 1.

[DasIllu]

I always had an issue with the labeling and the subsequent misdirection by calling the inputs positive and negative.
I made it an effort to get that out of my head as soon as i started to understand OpAmps a bit better.
Inverting- and Non-Inverting input is a better description, imho. It might seem "even more techno babble" to the uninitiated, but i think it helps in the long run.
Once you start seeing the inputs like this and not "so this is where positive voltage goes and this is where negative voltage goes", you can start using the opamps to manipulate signals to your own liking. That is why i see the labeling as a pitfall for people just starting to learn electronics.