EEVblog #600 - OpAmps Tutorial - What is an Operational Amplifier?
Why Electrical Engineering Stack Exchange recommends it
Electronics Stack Exchange answerers and commenters point beginners to it whenever op-amp basics, virtual ground or feedback confusion come up.
Recommended by 8 people across 9 different months, 2015 to 2023.
What it is
A 49-minute tutorial from the EEVblog channel in which Dave Jones explains what operational amplifiers are and how they work. It covers negative feedback, open loop gain, virtual ground, and the common configurations (comparator, buffer, inverting, non-inverting, differential, integrator), then finishes with a breadboard demo of virtual ground and rail limits.
What people said
Strong rec Alex Hajnal · 2022-04 · Electrical Engineering Stack Exchange · on “Is there a big difference between different opamps?”
Dave Jones did an excellent introductory video on this topic: "OpAmps Tutorial - What is an Operational Amplifier?" [this video] It covers all the basics of op-amp theory, selection, and use. (Apologies for the link-only answer)
Recommends Pedro Nadolny · 2015-10 · Electrical Engineering Stack Exchange · on “Is there a virtual ground in this op-amp?”
The op-amp is able to make that pin a virtual ground because of the feedback configuration you have. He will drive a signal through that resistor to try to cancel out whatever signal comes in the negative pin. You can check this quite long video out if you have some time, probably the first half of it will be enought for you to anwser your questions. Video Link [this video]
Recommends nitro2k01 · 2017-02 · Electrical Engineering Stack Exchange · on “Are thin connections between ground planes "islands" acceptable for ~0.5mA?”
@jagjordi It means that the input are unconnected. The opamp amplifies the difference between the inputs. If there's no feedback, the opamp will work as a comparator and drive the output either fully high or fully low. If the inputs are unconnected, they may pick up interference which could make the output swing from low to high to low very fast. This could propagate noise into supply rails or the other amplifier in the chip. Here's am EEVBlog video explaining some opamp theory which might be useful to you: [this video]
Recommends Harry Svensson · 2018-02 · Electrical Engineering Stack Exchange · on “RC Op-Amp Circuit Analysis”
You should have a look at this [this video] (49m:31s) video by Dave Jones where he explains what an op-amp is and how it works. It helped me when none of my teachers could get down on my level.
Recommends Harry Svensson · 2018-09 · Electrical Engineering Stack Exchange · on “Can an OpAmp be built without an IC or transistor or a Vacuum tube?”
@johnny Don't forget to watch this video by Dave Jones [this video] . It certainly helped me when I was where you are now.
Recommends root-aj · 2019-03 · Electrical Engineering Stack Exchange · on “How to Amplify Thermocouples (and DC sensors between 1mV and 1µV DC)?”
This is a bad idea, I know Here's what I know about amplifying really tiny DC voltages: it's impractical to build your own for production there's going to be noise the signal is relative to the cold junction temperature it would be easier with an ASIC than using basic components most op amps aren't rail-to-rail (can't go to 0) These are all acceptable to me . I want to learn how to do it anyway. Background I've just started self-teaching and I thought that measuring the actual temperature in my toaster oven with what I have laying around (batteries, resistors, thermocouples, resistors, and op amps) would be a fairly simple and easy first project to design myself. Maybe I'm wrong, but I belie
Recommends Bimpelrekkie · 2019-09 · Electrical Engineering Stack Exchange · on “Opamp compensating circuit”
If you want to learn about opamps I recommend reading the free ebook, *opamps for everyone*: [LINK] and also watch the videos made by Dave from the EEVBlog: [this video]
Recommends Nyos · 2019-11 · Electrical Engineering Stack Exchange · on “How does an ideal op amp amplify a voltage input when the voltage difference is 0?”
Dave from EEVblog had an bit long, but excellent tutorial on opamps: [this video] Watch it, and come back if you still have a question.
Recommends Christianidis Vasileios · 2021-03 · Electrical Engineering Stack Exchange · on “Why in op-amp inverting circuits one of the op-amp inputs is grounded?”
I would recommend starting here: Eevblog's video on op amps [this video] . You can find the questions to your answers just by googling " Virtual ground op amp [LINK] ". There is a ton of material out there regarding your question :)
Cites lucenzo97 · 2017-01 · Electrical Engineering Stack Exchange · on “Define input current of Op-Amp”
I haven't done and studies in Op-Amp category yet but I watched a (trusted) video on Youtube and one thing is not quite logical as the next sentence: "No current flows in or out of the inputs of operational amplifier", as says Dave Jones from EEVblog on Youtube (this video: [this video] ). So, I am wondering if he meant like there is a really small amount of current flowing in op-amp on the inputs, or there isn't any of current on inputs at all? I am sure there must be at least some current on inputs (for base if BJT or for gate if FET/MOSFET for sure). [LINK]