Operational Amplifier Tutorial - Basic Non-Inverting Op Amp (Part 2)

[CheddarBob39]

Very good videos, thank you for making them. ( : My teacher is pretty good at teaching but during that class(the first one in the morning) I am usually tired as hell and am just fighting to stay awake and don't end up taking anything in.

[TrueSolarDay]

I've only watched two of your videos and both were excellent. I saved you to my favorites!

[mamaood]

cool! Dude you explained in 15 mins what my prof was mumbling about for an hour!

[paulthecoolest]

Wow you are really passionate, aren't you ,it does come through..

[TheBlacksnipper]

huh? XD

[chychyness]

mwuah.. :p

[anbadhwar]

Your videos are so helpful and time saving, Thank you drjctu.

Are you a professor at university?

[keo515]

So much more well-explained than my lecturer. Thanks!

[Ivin3690]

omg u answered my exact questions, it was almost creepy!! thank u!!

[taimurkahn62]

awsum lecture 

[nsmith1002]

From Wikiperdia page on operational amplifiers: "An op-amp produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals." Bit if the inputs are ALWAYS equal then there can NEVER be a difference between them to be amplified! I see other people have posted similar things here, so I know I'm not alone in not understanding this. Does anyone have a concise explanation?

[drjctu]

@nsmith1002 Output of op amp is vo=Av(vp-vn) where Av is the voltage gain of op amp, vp is the noninverting input and vn is the inverting input. Now, for an IDEAL op amp Av=very large or infinite. Then, vp-vn=vo/Av=0 or vp=vn. This relationship vp=vn is used for analyzing an op amp. When we use this equation and ip=in=0 (ideal), then the gain of an op amp with FEEDBACK (closed-loop) is only dependent on the external feedback components since the gain is infinite in the open loop case. Dr J

[meme2342]

@drjctu Ok, I kind of see what you are saying, but if (vp-vn)=0, then surely vo=Av*0=0... Is this due to a difference between the 'ideal' op amp on which these assumptions are made and 'real' op amp amplications? P.S. keep up the good work with the tutorials I wish you were my lecturer!

[meme2342]

@drjctu Ok, I kind of see what you are saying, but if (vp-vn)=0, then surely vo=Av*0=0... Is this due to a difference between the 'ideal' op amp on which these assumptions are made and 'real' op amp amplications? P.S. keep up the good work with the tutorials I wish you were my lecturer!

[vXxo0oxXv]

@drjctu This makes more sense. Thank you. basically Ri is not infinite, but it is so high that you use it as an infinite value for simplification of circuit analysis. Of course, I'd assume this leaves a small margin of error with calculations done using Ri an an infinite value. To be more accurate, you'd have to use the 10^6 ohms through 10^12ohms value you mentioned. Which adds unecessary complications for the amount of correction you'd have using that value. Is this correct?

[nsmith1002]

Sorry, but I find this presentation VERY confusing! Am I understanding correctly that the inputs to the op amp are AWAYS equal?

[tp019966]

I love you !!!!!!!!!!!!!!!!!!!!!!!!

[alitou001]

Thank you so much Doctor, I am so happy I ve found your tutorials.

[TheVynci]

thank you a 1000x !!!

[allenh98]

THX

[pheeson]

Dude, you're a life saver

I have an assignment on this and our teacher can't explain shit.

[EDWARDALFONZO19]

@pheeson I feel you bro.

[matatan69]

Thank you soooooooooo much.. you explain so good.

[diwakarsingh143]

you made this look so simple .thank you so much :)

[ventureelect]

Great video.thanks

[tinku6565]

thankyou verymuch!!! your videos are soo helpful!!

[TwilightTinyTim]

Thank you Thank you Thank you!

[jackson32]

How can vp be the same as vn when there is a voltage drop at r2?

[Rajputo]

@jackson32 The current going into Vp and Vm are both 0. that is something we assume for an ideal operational amplifier

[jackson32]

Why does an ideal op-amp have zero difference between its inputs and if there is zero difference doesn't that mean that there would zero output?

[Nadrealis]

@jackson32 something having zero difference doesn't mean there is zero output. There is still input being put into the OP-AMP.

[dawance88]

You are a MAESTRO! Thanks SOOOOOOOOOOOOOOOOOOOOO MUCH!!!

[boong88]

thanks a lot... good explanation

[rkityl]

thanks man.. serious been a great help

[sarasaharsara]

Thank you for the video. I need to make an amplifier (circuit) that takes a very small DC current and amplifies. My major is materials science and I basically don't know much about circuits. I learnt some stuff from online searches and your video but I was wondering if you could help more if I gave you more details. thanks

[t2vietnamese]

very helpful

[drjctu]

Thanks.  Dr J

[trailbuddi]

Is it good to think of an OP Amp as a "(hardware) programmable amp" perhaps?

[drjctu]

Now if you hook up a digital potentiometer for the input or feedback resistor then you can think of it as a programmable amplifier with gain. Hope this helps! Dr J