Operational Amplifiers - Differential Amplifiers

Description of what a differential amplifier is along with the derivation of the equation relating input to output (hint: it's based on the difference between the two input signals).

[JamesBond-jpep]

I spent 2 hours on the net, then I found this video and my problem was solved in 5 min.

Man, you should be my Professor!!
Thanks a lot

[LockDots]

This was so much better than the way two of my professors put it. Thanks so much David!

[MrAlbashiri]

Finally there is somebody that explains it. Thank you so much sir for the great video.

[charleswolfe]

I understand everything until the algebra at the very very end. My textbook does not explain the algebra, and no video ever explains the algebra. If R1=R2 and Rf=Rg, how does that reduce to the simple expression you end up with?

[znuos]

thanks, now i finally understand it. my lector skipped the big expression and assumed that R1=R2 and Rf= Rg but now i see from where it comes :)

[Frank-gvfs]

i had a messy version of this on an assignment and with your insight on superposition i can now solve my homework, thank you

[timmyshiznit]

What happens if you have Rg connected to another source instead of ground?

[garrettherrmann]

Why isn't the voltage in V- = V2*(R2+RG)/(R2^2*RG)? I'm trying to use node voltage analysis and I'm not getting the right answer.

[ElectronXLab]

@08R6dude What I did was use the superposition principle. I calculated Vout if V1 was the only input, then calculated Vout if V2 was the only input, then I added these two terms together to get the overall Vout. Does that answer your question?

[alexanderdepaemelaere]

Because of this vid, everything became clear and I could solve all the exercises (correctly xp). Thanks you so much!

[bobyk]

Modern Vox AC15C1 has one as a mixing stage of its two channels before going to reverb and so on. But it has different resistor values so that the hot (topb.) channel signal is a bit attenuated.

[byllgrim]

Sweet! Knowledge revolution. Think of all the duplication of effort which will be reduced when learning facilities finally utilize the internet properly! Humanity will thrive, I'll tell you.

[ElectronXLab]

I use OneNote along with a Wacom tablet for equations and notes etc.

[Cittamatra]

Why do we need R2 and Rg? What happens if we remove these resistors, and have V2 applied directly onto the (+) input of the op-amp?

[ctigu]

Excellent. This is the best and clearest explaination yet. Many thanks

[sallauddin]

It couldn't be any better explained, thank you!

[Bruh-zgyk]

Final Exam in 25m… no one had explained it like this 😭 thank youuuu

[lehlogonolomonaise]

Please help me Build an opamp based current to voltage converter that will give an output of 0v at 4 mA and 5v at 20mA

[Flounderhouse]

Why do you assume the V- terminal is 0 (virtual ground), but then not for the V+ terminal (V+ = Rg /(R2+Rg))...? I mean if the two terminals are equal, and one of them is zero, then why suddenly assume there exists a voltage across Rg? When I analyze these circuits when can I assume a terminal is virtual ground (and equal to zero)?? And when can I assume the terminals are equal to each other?

[schafbo]

How do you find common mode and differential mode gain?