I know this will probably get lost in the comments but I have to say it. I absolutely have a high respect for people like you who share knowledge so freely and willingly. People like you are a godsend. Thank you sincerely.
This is the first instance where a lecturer explains that op amps should'nt be treated as the same amplifiers theyre made of and that broke the wall id been stuck behind. Catching up on homework as I watch. Wish me luck.
+Kenneth Tan blew my mind when I finally figured out why they use a buffer on an inverting op-amp. It's the simple things that others take for granted. These videos are chucked full of informational tid bits one should store away my understanding of circuit design is getting better with each eevblog
+RRClassicman This is true fact about formal education, mostly in schools you learn almost nothing! That is situacion in Croatia, just a lot of unnecessary material with zero interactivity with the student
what makes you a gorgeous teacher is that you not only talk about what is going on but also about what the follower might think is going on but actually is not and why. i had so many frustrating experiences in the past because of teachers that did'nt care about that. i truly love your lessons.
As a retired Senior Applications Engineer at Burr-Brown and Texas Instruments, I must compliment you on this presentation! It is very similar to the "factory" technical presentations that we used to give to audiences around the globe. The technical level is just right, not to basic and not too advanced. Good job! To be a good teacher it takes far more than just knowledge of the subject. A teacher's job is to impart knowledge to his student; if the student doesn't understand, the teacher is not doing his job. Some PhDs can teach, others can't- Richard Feynman was an example of a fellow who not only thoroughly understood his subject but who could teach it as well.... and do it in an interesting and entertaining manner.
@@youtubegoogle4163 I just gave this reaction below, but i think it's the sink current working very close to the maximum rating: the sink current for Vout=200mV is only 50uA, and goes quickly up to 20mA at Vo=2V. Because of the 10k resitor for R2 it's working very close to it's maximum ratings at the lower end. 0.5V out is 50uA sink current. And (apparently) in practice this results in the weird ground spike that fck ups the output.
@@youtubegoogle4163 Looks like crossover distortion, the switch from sinking to sourcing current... and at the point when this happens the opamp is neither sinking nor sourcing correctly, so the negative feedback stops working properly and the input voltage is allowed to spike momentarily.
This is my new favorite TH-cam channel!!! I am a marine engineer by trade, but I started getting bored, so I signed up for an online electronic engineering programme at my local university, to put my spare time into good use. I have never gained much from sitting in a classroom listening to a lecturer bleating for two hours at a blackboard, so I was thrilled, when I got the opportunity to work at getting a degree, working by myself at home. These videos are an absolutely excellent supplement to all the videos available from my university. Thank you!!!
Wow good for you! :) That's so weird. Reminds me of a line from the movie predestination, "luck, is the residue of planning." It's so true. When you work hard for something, luck helps you along the way, more often than not in bad situations. Was that the case with you? Btw I'm in my 3rd year in EE, my school isn't so glorious if u know what I mean. So It's hard trying to become an autodidact, especially with complex matters which don't always have the clear specific explaination on the internet... Sorry for rambling lol
@@microdesigns2000 The job this video helped me get was a great place to start I had an excellent mentor there and i worked there for 2 years. I have since changed employer with a more embedded and programming focus I have been at this subsequent job for 2 years and 2 months now! Although it was over 4 years ago i still remember the night before the interview trying to cover everyrhing they might ask and watching great videos like this.
@@microdesigns2000 I work mainly on low power IoT projects now . I also do home projects too . id like to start my own electronics design business one day!
Very helpful. I'm an electronics technician and you see this stuff when you're doing repairs or troubleshooting but you never get down to the nitty gritty details especially after 30+ or so years goes by from your initial electronics training so it was really nice of you to explain this especially on layman's terms. Someone else mentioned in this blog about cutting and pasting working circuits into projects and calculating as you went along to fit your needs which is pretty much what I've done in the past so this has really been a BIG help in the memory refresh department. Thank you ten times over and may the "electro" Gods shine good fortune down upon you sir!
electronic technicians nowdays repair FLAT TVs, monitors, cell phones, install and repair satellite installations, alarm systems, fire detection systems, CCTV installation, PLC programming and maintenance in industrial applications, and a variety of other applications ... Nowadays, even the electrical appliances of a hotel kitchen may have electronic control boards with fiber optic and internet connectivity. And in some countries it is not always "throw the old board away and put the new one" this is the easy way that even a 10 yo child can do. What if a new electronic board is too expensive ?
Hi dave I've been watching your channel a lot for the last couple years now and it's fantastic! I'm currently doing my honors in electronics engineering and my University here in hamilton New Zealand has instructed my class to watch this video on the current section we are covering on op-amps. You have finally made it to university level teaching my friend!
Most excellent basic introduction to op-amps I know of. It tells you everything you need to know about fundamental operations of op-amps to get you on your way to understanding more complex circuits.
Regarding the puzzle at the end, the low resistance effect is an increased current at the OA output. the OA at approximately Vout= -0.5V should sink 50uA which is higher than the value in the datasheet/figure13 of 30uA max. so the virtual ground voltage fluctuates and so does the output at approx. -0.5V.
@@cireekratz2017 Above explanation said. at Vout = -0.5V I sink = 50uA (> 30uA) Can you please explain me, What special thing happens at -0.5 V, Which doesn't happens at other output voltages ?
@@youtubegoogle4163 Hi, the thing is, that this IC has limited current sinking capabilities at low negative output voltages. In the -0.5V case the sinked current should be (-0.5V/10kOhm) 50 uA. But the IC is not capable to sink that much current at this V_out. Figure 47 in the datasheet shows that it only can handle ~40mA. Now there are 2 cases: - slightly higher V_out (like -0.25V): the sink current lowers to 25 uA and that is just in the limit that can be provided (when the supply V difference is at 30V, grey curve) After that the virtual GND can begin to deteriorate. - lower V_out (like -0.75V): the current sink capability of the IC rises rapidly (after the kink in the curve). It lands around 1.15mA which is sufficient by far. In the end Dave chose a really nice corner case, where there is only 1 output voltage, where this problem arises. If you lower the R values further, the problem should expand and should arise shortly after V_out = 0V and stretch to around -0.6V. Hope this helps.
Your video is gold. I modeled both inv amp and non-inv amp in LTspice with MAX4352 op-amp. Input voltage: [0,0.5] volts. Vcc:+5v, Vee: GND. Worked perfect. Thanks for your work!
When I learned how to use Op-Amps, the 741 was the state of the art at the time. Yes, had to learn them the hard way back in those days. What a great refresher course for this young man born 9-11-1946. Great job Dave and thank you. Respectfully, Steve
Dave, this is amazing. Thank you for these mini classes, honestly it’s worth more than any electronics class I ever paid for. Negative feedback op-amps just clicked into place for me about 10 minutes in. I had been struggling with this concept for days. Thank you so much.
It's so great to see fellow Australians showing up on TH-cam. Especially for something like explaining electricity. Bringing fame and reputation to our country!
I am in my senior year for EE and we had a whole 8 weeks in one of my circuit theory classes dedicated solely to op amps. We got to delve deep into these and do some really fun design problems and lab experiments. This video really is a great refresher and good start for anyone new to them.
I wish we had the time for that... I'm in my second year and we spent two days on op amps. This video helped me quite a bit. I guess we'll return to the op amps later on..
@@TheDaniel85 I am in my junior year, If anything interesting starts, it's going to be in 3rd, 4th year. First two years is just a dull foundation, during a third year pieces of puzzle will be coming together.
If anyone is interested the gain of the non-inverting config can be derived from the voltage divider equation: Vin = Vout*R1/(R1+Rf) Vin/Vout = R1/(R1+Rf) Vout/Vin = (R1+Rf)/R1 Vout/Vin = 1+Rf/R1 And the gain of the inverting config can be found from the currents: I(Rf) = Vout/Rf I(R1) = -Vin/R1 -> Current through both resistors is equal so... -Vin/R1 = Vout/Rf Vout/Vin = -Rf/R1 :)
Amazing how simple the above is when you can assume that the internal gain of the opamp is infinite. Everyone going through EE should be able to demonstrate the above in the time it takes to write it down. Well done.
This video got me a job as a tech earlier this year. I spent so much time reading different articles about it and struggled to wrap my head around it. In the interview they had a worksheet with ohms law voltage divers etc and then in the verbal portion he brought up op amps. I just started talking and after a bit he smiled and I knew I was hired. Thanks Dave!
Excellent discussion. Takes me back 35 years to my intro to op-amps. My professor explained what was to us an amazing and confusion subject just as you did and within a day or so we couldn't wait for the lab. I'm now hooked on your channel. atb Opal
Read this after 12:23 and listen to buffer amplifier again. The primary objective of buffer circuit is to boost the current in any circuit at any stage. Buffer circuits are mainly used where a signal has very low current input(high input impedance) which needs to be increased maintaining the same voltage levels. So, this buffer circuits draws current from power source and adds it to the signal. Buffer amp is also called as voltage follower or unity gain amplifier . Hope this makes sense now !
If my college lecturer in the 1970s in England had been just half as good as explaining things as you, I could have saved myself 40 years of stress thinking that I was an idiot. Keep up the excellent work, you obviously love passing on your knowledge and are brilliant at doing it. I am now totaly gripped.
Thanks for doing teaching vids, Dave! I took many electrical engineering courses in college and we did a lot with op-amps, but I'm embarrassed to admit I've completely forgotten everything about them since then. These practical introduction videos are perfect for people like me who want to reconnect to something we learned in the past. Thanks again!
Someone in my class has been spreading around this video to everyone and they're all raving about how useful your video is.
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Thanks to you, and your videos I am today a successful engineer working in semiconductor industry. I am just coming back, years after I watched this video for the first time. I was having problems passing the only one remaining subject to get my degree and was searching for a helpful video on opamps. Not only you helped me, but also inspired me with your positive personality! Keep up the good work!
i'm literally crying, thank you so much. my physics midterm is tomorrow and i truly thought i was screwed. but now i think i can save my grade, subscribed x
This video literaly saved me :), right now in the university everything is going on-line and some teacher are just an assholes that don't care if we are learning with this new method and I mean, there is this one teacher that literaly send us to read a book and that´s it, nothing more, and well, I think this is the best class about op amps I have right now. Thank you so much
tonight i learned 10x more about op-amps, and with a deeper understanding, than i did in a whole semester in a suffocating classroom. Thank you for your time.
What the hell just happened? I felt like I had watched a 10 min video. By the time I looked at the time line, 49 minutes had already passed. Magic OOOOoooooo. XD
Wow, huge thanks for a crystal clear explaination! I have watched several other videos where others tried to show how awesome opamps are and after those videos I became more confused. At last, thanks to your awesome video I understand what it is and how I can use them. Awesome Dave, it´s like christmas following your videos.
We're moving into Op-Amps in my 2nd year circuits class, and I've already gone through 3 shorter "intro to op amps / op amp basics" videos with high view counts and all of them were rubbish in terms of being "basic introductions". This 50 minute video is already vastly superior in presenting the fundamentals clearly and simply in the first 5 minutes. Happy to have found it!
Even after 30 years away from electronics I got the gist of you lesson, thanks you explain it very well and in manner I just love. I worked in the dept of Navy as a trainee and we had two parts, one was a TAFE course the other was direct from Naval lecturers. The naval lecturers were like you extremely conversant and able to explain in a much more understandable manner.
This brings back memories. I learned all this in studying for by BSEE degree that I got in 1976. I have no idea why TH-cam sent me here. The last video I watched was on modeling an MOV surge protector in LTSpice. I dozed off and wound up here. Back in 1976 we had a saying: *_”Four years ago I couldn’t spell ‘injuneer’ and now I are one!”_*
Dave, though i've never met you or even had a two-way communication with you i do see you as my friend and tutor. Maybe it's simply because you come across as a really nice guy in your vblog, and i've seen so much of your face and so much appreciate your educational skills. Maybe it's becuse with you as my major source of education i've had the best grades in every course i've taken over the last 18 months, spending close to no time at all studying, giving me time to earn some well needed cash for equipment, working as a private tutor for other students, and that was not even deliberate. I was approached by peers who wanted tutoring and insisted on paying me for it, reasoning that their parents were prepared to pay the tripple amount to an actual professor who would no likely be any better than any of our own teachers, working out of the same curriculum, and that they knew from class that they understood me way better than any teacher. Because every teacher we've ever had can take hours trying to explain these concepts to no avail, but using sometimes slightly modified (just enough to fit exactly the concept we're studying and the specific questions the sometimes slighly slow teacher wants answered at that moment) versions of what you've taught me i can explain concepts so that my peers understand them well enough to get at least a C in a matter of a few sentences. No matter what knowledge gaps my teachers have left behind i can fill them in, in a matter of minutes and almost never having to explain something twice to anyone, ever, using your pedagogic models! 9/10 times when i explain something the answer is something like "Ahaaa! Oh my god i feel so dumb, it's not even that complicated!" A lot of people don't appeciate the fact that the ability to understand something better than others, doesn't magically give you the ability to describe it in a way so that those that don't understand it can also do so! It's not just that i have complete confidence in the quality of the information you provide, it's your ability to explain thing that would have taken me hours or days to figure out, if at all, in a matter of seconds or minutes. In fact the service you provide me, absolutely for free, saves me so much time (generally in between 10-20 hours a week in school. Is this even real?!!!!! o____0 ) since i don't have to study anymore to get top grades and not be the teacher's pet but rather his assistant! So... The fact of the matter Dave, is that i basically owe you roughly 17% of my total spare time, weekends included! Those are 17% of the part of my life that i get to spend as my heart desires. And i simply just can't thank you for that in writing, because whatever words i chose would be an insult to your genius! But still, i do have to say something so a simpler thank you will have to suffice. Thank you professor Dave, thank you so very very much! The quality of the service you provide is in my experience unprecedented in any and all forums from the web to actual traditional education in a "real" school. I hope that you love doing what you're doing as much as i love watching you do it, and that you will keep doing this for a long, long time! Your devoted fan and pupil, Fredrik Sjöblom, Stockholm, Sweden.
Excellent video Dave! Concerning the puzzle on the end. I think it's the reduced current sinking capabilities of the LM358 when Vout is small in respect to ground. If look up the "Output Characteristics Current Sinking" graph in the datasheet you can see that the LM358 can sink very little current at low output voltages. As you have a 1k R1 and 2Vpp input voltage you have 2mApp of current, which is still too much to sink for the LM358 at low output voltages. So the LM358 can't keep the virtual ground equal with the "real" ground trough it's FB network. Therefore you get those spikes and the sagging and rising of the virtual ground in between.
You are right, just a small clarification. the OA at Vout= -0.5V should sink 50uA which is higher than the value in the datasheet/figure13 of 30uA max. so the virtual ground voltage fluctuates and so does the output at approx. -0.5V.
+TheElectr0nicus but why does it jump like that? And why is there such a weird knee in the sink around that voltage (i.e. the physical reason for the fact that it goes closer to linear at even lower voltages)
+Edith Mejia what would be the fun in that? Don't you enjoy not understanding something and then spending hours online looking for information...for free? I know I do! (that's a lie)
Great explanations. I used OpAmps before, but more copy-and-paste style, just using the standard circuits without thinking about it. Now it makes sense why it works, and with the two rules I might even create equations to analyze more complex circuits, like the differential amplifier, where you've lost me a bit.
I'm not sure what the issue is. Analyze it like any other inverting amp. The voltage at the inverting input sets the voltage at the non-inverting input: 0.91091V. The voltage drop through the inverting R1 1K resistor is 1.1V - 0.91091V, or 0.1909V. The current through the inverting R1 and sunk by this inverting op amp through the feedback circuit is 0.19091V / 1K, or 0.1909 mA. The voltage drop across the feedback resistor R2 is 0.1909 mA x 10K, or 1.9V. The voltage at the op-amp's output is the voltage at the inverting input less the voltage drop of the feedback resistor, R2: 0.9191V - 1.9V, or about -1V. As a check. the voltage gain formula is -R2/R1, or -10K/1K = -10. The difference in voltage at the inverting and non-inverting inputs is 0.1V. So, the op-amp's output using the gain formula is .1V X -10, or -1V.
You are a brilliant teacher. Your ability to explain these concepts in an easily understood and straightforward way is a precious gift. I say this as someone who, many many decades ago, struggled as a student trying to understand so many instructors who did not have the ability to convey their knowledge to their students.
Took years to comprehend this stuff. Especially when it came to more complex circuitry and control of DC motors from controlling speed, current, volts, positioning, etc. Great video and spot on! Thanks
Back in May of 1978 I started work at an aerospace company that made the engine controllers for a military jet aircraft. The engine controller was a low frequency (less than 10 KHz) precision analogue computer that had amplifier gains & offsets calibrated to +/- 2 mV with select on test 1% tolerance resistors. Some critical circuits in the controller used 0.1% tolerance resistors. Positive 10 V and negative 10 V references were used throughout, and as well as the usual feedback loop components there were two 10.6 V Zener diodes in each loop. All of the virtual earths were connected to a virtual earth monitor that used a high gain amplifier to indicate any opamp failures. After a few years the engine controller was redesigned around 12 MHz 16 bit microprocessors and was considered to be not as good as the analogue version because at full speed the aircraft would travel about 50 feet before the software loop was reiterated. Some of the circuitry in the analogue version was very unusual and complex and I learned a lot about circuit design with opamps. It was a great place to work because there were occasions when batches of high grade components were thrown into a skip, and the company didn't care where they went. To this day I have a huge stock of mostly obsolete but still useful components that I use for making projects and stuff that can't be purchased off the shelf. Thanks for the video.
It's amazing how bored teachers can make something not that complicated look like a mountain.. I never ever understood opamps at school, and after a fews minutes in now, i'm like... How the hell did they manage to overcomplicate that???
I studied and played around with this stuff over 40 years ago, it's quite refreshing watching these videos. I went into digital for many years practically ignoring analog. Thank you Dave.
Great explanation, you just took the best OP-Amp explanation until now from:YT- John Santiago Op Amp Design Basics - Inverting Amplifier - Part 3 (i was actually wondering when you will do that 8-). While you mentioned ohm's law you might add Kirchhoff circuit law in the part where you "wonder" about where current goes and that lack of minus in inv. OP gain formula was bugging me until you corrected it... For the end, you put smaller resistor which drives 10x larger current form output trough feedback resistor to "match/counter" input current (100uAmpsp rise into 1mAp) so output stage switches into B class (whole chip with 2xOPAmps has less then 1mA quiescent current and output stage probably uses about 70% of that) and you see clear crossover distortion on the output waveform (where OP-Amp loses control hence the spikes on the input, you can represent that as vehicle steering wheel dead play for mechanical types) Great video, just took best opamp explanation title,cant wait for #2,3,....
this video (as old as it is) really helped my early on while studying my degree, then even now years later i watched it day before i went into the job interview of my dreams, and it may well have been the contributing factor that landed me the job. so a huuuuge thanks.
unbelievable, what a master class. this teacher deserves his salary. I honestly want to make a donation. you made my day. I never laughed so much in class as I did in this video with you!! :)) he does not only explain it amazingly well, but also makes it entertaining. 10 points
good ol crossover-distortion. the LM358 has a class-B output stage and has to be biased properly or you get crossover distortion. instead of having diodes in the output stage, they tied the bases together. They were designed to be low power, so they did this. a proper load resistor between the output and negative supply will fix this problem. decreasing the feedback resistors increase the load by decreasing the overall impedance to the "virtual-ground", causing more and more crossover distortion. There is a tradeoff, by putting a resistor in the output stage to -ve, you also get a much higher idle current. Much more than of a standard class-ab op-amp. So that blows the "low-power" rating into the rubbish bin. Edited as my first couple attempts didnt sound, or come out right.
Yeah, found that explanation in about ten places on the net, none of them bothered to explain how the missing load resistor influences anything - they all went way, way above the 'dummie level' this video is addressing (and most certainly outside its scope). Kind of like the answer above, actually. Would you please elaborate a bit on that - I freely admit to being a proper dummy in any of this analog stuff...?
Attila Asztalos Im going to leave that one to Dave as he is going to explain it better than I ever would. From what I understood years ago, is there is a small current source in the IC that needs beefed up by the resistor to bias the output stage into conduction on both transistors instead of just one. its class-B for a reason, one is because its low power, 2 is because it can reach ground whereas true class-AB cannot, at least not without some help. Amplifier classes are explained on the web in various places, but class B means its biased into cutoff. Meaning at idle with no signal present, the transistor is switched off. Raising the input voltage approximately 0.7V into forward-bias, the transistors will begin to turn on. When the output signal reverses below 0.7v, the transistor is off. Then as it swings below 0, into -0.7v then it will switch on again. (lower transistor). That creates a dead-zone of approximately 1.4v that the amplifier isnt conducting. This creates crossover distortion. The external resistor increases the source current to the bias network, adding extra idle voltage/current into the output stage allowing the transistors to stay on all the time, known as class AB, or for some reason in the LM358's case, Class-A. Edit: Looked at the datasheet, the texas instruments datasheet on page 11 explains it all.
And now we need a second part, where you show us the non-common circuits, as let say...Gyrator-stuff, Log-converters, average/peak rectifiers, and "interferences" when using OpAmps in RF circuits (like input pin reversion)....;)
was'nt too sure at first about the teaching style but after a few moments. lights were going grower much brighter! you never really lost a monent. very nicely articulated tutorial of an Opp. Amp. specialy as a refresher. since it's been 20 years practiculy. very nice ,will be following up . good work , can tell you love it bravo!!!
I was am A student in my EET school and did great w the math, understood digit TTL.... But when we got to analog chips like the Op Amp, I just couldn't grasp it w a gut intuition, and started to get behind the instructor, constantly playing catchup. I didn't have problems w the math, but since I didn't have that intuition I was just plugging in numbers and not understanding the fundamentals. I had no idea what the 741 was able to do, what it was for, and completely flummoxed when the amplifier circuits were combined w other chips and components. When Dave started out by erasing that scary looking circuit and the math, I was like, ah ha! His method of starting w the basics got me thinking after 30 years, I'm finally gonna be able to comprehend this! For years, I was so intimidated by the 741 that I'd quickly become discouraged when circuits had them and I'd just give up and would just mindlessly follow the schematic and solder em in. Those days are coming to an end. Thanks, Dave. If it weren't for Dave TV, grasping this would be a whole lot harder. Stand aside, Mr 741 Op Amp!
That's because he has designed so much own circuits Was a professional electronic designer Invented 32 channel logic analyser in the 80s Played with lot of op amps and some professors have never used a 741
Whatever haven't tought for x amount of reasons eg lack of access to higher education, means of funds, have a chance to broaden my knowledge and horizons thanks to you and a few other persons like you. A huge thank you is certainly not enough.
LOrd! Where do I start. This is the best tutorial I've ever experienced. You literally just saved me failure in less than an hour while other lectures are taking entire semesters to attempt doing so and still failing. THANK YOU!
@@thatcrazywolf You mean what type exactly? 😂😂 MOSFET ? BJT ? IGBT ? Under BJT PNP or NPN? Under MOSFET Depletion or enhancement type? All I mean is really??? 😂
Hey Dave, can your next video be on the stuff you crossed out? I wanted to cry there for a sec. There are tons and tons of resources about the basics of op amps, there a dime a dozen. However, there are very very few complete videos on op amp internals. Finding videos on the basics is utterly simple but finding well presented videos on more advance material such as op amp internals is painfully difficult.
This video contains more information than half of semester of electronics on my university and thanks to it I have maxed one of two tests required to complete the course in about 20 minutes
The teachers have to include all of the unnecessary theory involved as if there is no IC, but we can't repair the IC, only replace it and you're starting from scratch which is not needed unless you plan to make your own IC and half of these teachers speak in monotone and barely grasp what they're reading so when you ask certain questions they will look it up and attempt to explain, but there are the exceptional that really know and they have a way to explain because they have the full understanding.
BINGO!!!! Suddenly it came clear at about 10:00 how simple it is to use these devices! I have a compartment in my component collection of OpAmps that I purchased for a device I needed to build, and as you know, you can hardly buy just one, so, of course, I purchased 10, and promptly forgot what I purchased them for, because the order came in from China about 35 days after I placed it, and the notion of what I was building had been replaced by something else completely, so I have all these OpAmps and nothing to do with them. Thankfully I came across your video, so I may well begin to play with them when I get back from our Winter quarters in Arizona and return to my home in South Dakota, where they are under a full fledged blizzard warning as I type, and here in Arizona, we are under a wind warning with the temps at 65 degrees F. Oh what a difference some 1500 miles can make!
I know this will probably get lost in the comments but I have to say it. I absolutely have a high respect for people like you who share knowledge so freely and willingly. People like you are a godsend. Thank you sincerely.
it didn't get lost in the comments!!!!!!
@@不知所错 We're all lost my friend.
I totally agree dude…. we’re so fortunate to have people like this dude
Came up as the first comment... 🙂 The mysterious ways of the youtube algorithm will never be comprehensible for us "ordinary people" 😎
This guy is DATA from Startrek ];-D.
Six years later, this is still the best and most understandable intro to Op Amps ever.
This is the first instance where a lecturer explains that op amps should'nt be treated as the same amplifiers theyre made of and that broke the wall id been stuck behind. Catching up on homework as I watch. Wish me luck.
That's for sure. I wish I had professor like him.
One reason that I have never excelled in school is because most of my teachers were the oposite of this guy, their lectures were dull and incomplete.
This guy is DATA from Startrek ];-D.
Had to watch this video to make sense of my class lecture on op amps. Funny that I have to watch a free video to make sense of a paid class
Been a tech for 43 years and I have never seen it explained so concise. Thanks and I am turning the junior techs onto this video. Cheers!
Eight years later, this is still the best and most understandable intro to Op Amps ever.
I Learned more in 10 min of your video than 1 month of my Power Control Electronics class. Thank you!!!!!
+RRClassicman Glad to hear! (well, kinda...)
+RRClassicman Well 50 minutes in my case. It changed my biased "OMG an OpAmp" to "OpAmps, I love'em"
+Kenneth Tan blew my mind when I finally figured out why they use a buffer on an inverting op-amp. It's the simple things that others take for granted. These videos are chucked full of informational tid bits one should store away
my understanding of circuit design is getting better with each eevblog
+RRClassicman This is true fact about formal education, mostly in schools you learn almost nothing! That is situacion in Croatia, just a lot of unnecessary material with zero interactivity with the student
+Blade Runner Well, in a TH-cam video, there's also 0 interactivity with the student ;) Other than that, you're 100% right.
what makes you a gorgeous teacher is that you not only talk about what is going on but also about what the follower might think is going on but actually is not and why. i had so many frustrating experiences in the past because of teachers that did'nt care about that. i truly love your lessons.
Mirko Mueller it's also great to see someone enthusiastic about what he does.
Mirko Mueller So are you enthralled?
A good teacher.
48:40
Can anybody please tell me the reason of this ?
5.300 students are very grateful you uploaded this video
+95berre count me in!
You can't have 5.3 students.
As a retired Senior Applications Engineer at Burr-Brown and Texas Instruments, I must compliment you on this presentation! It is very similar to the "factory" technical presentations that we used to give to audiences around the globe. The technical level is just right, not to basic and not too advanced. Good job! To be a good teacher it takes far more than just knowledge of the subject. A teacher's job is to impart knowledge to his student; if the student doesn't understand, the teacher is not doing his job. Some PhDs can teach, others can't- Richard Feynman was an example of a fellow who not only thoroughly understood his subject but who could teach it as well.... and do it in an interesting and entertaining manner.
How i can get a job in TI ?😅😅😅i mean its awkward to ask this way but yeah
Sorry beforehand 😅😅
@@naveengupta5588 The best way is to send in a copy of your resume. Good luck- the world needs more analog engineers.
@@neilalbaugh4793 could you please suggest best book for Analog electronics for beginners
But that isn't always the case. A teacher can be competent, but only to find that he's teaching students who don't study.
In my whole electronics major shit , I have never seen a person who explains virtual ground like this.
#RESPECT
This term makes no sense
@@StEvUgnIn Abolutely no sense.
He’s amazing love it,,I’ll figure it out virtual ground oupps
It’s spiritual
@@StEvUgnIn Does the "virtual ground" means 0V ?? If so then it really doesn't make any sense 🤦♂️🤦♂️
"The gain is almost infinite"
spoken like a true engineer!
A power speaker guidance glee Iowa amp it up yeah
48:40
Can anybody please tell me the reason of this ?
@@youtubegoogle4163 I just gave this reaction below, but i think it's the sink current working very close to the maximum rating:
the sink current for Vout=200mV is only 50uA, and goes quickly up to 20mA at Vo=2V. Because of the 10k resitor for R2 it's working very close to it's maximum ratings at the lower end. 0.5V out is 50uA sink current. And (apparently) in practice this results in the weird ground spike that fck ups the output.
@@youtubegoogle4163 Looks like crossover distortion, the switch from sinking to sourcing current... and at the point when this happens the opamp is neither sinking nor sourcing correctly, so the negative feedback stops working properly and the input voltage is allowed to spike momentarily.
and the open loop bandwidth is darn near zero Hz.
Interestingly I just recently recommended someone to look into using an opamp for their project...
EEVblog never disappoints.
This is my new favorite TH-cam channel!!! I am a marine engineer by trade, but I started getting bored, so I signed up for an online electronic engineering programme at my local university, to put my spare time into good use.
I have never gained much from sitting in a classroom listening to a lecturer bleating for two hours at a blackboard, so I was thrilled, when I got the opportunity to work at getting a degree, working by myself at home. These videos are an absolutely excellent supplement to all the videos available from my university.
Thank you!!!
this video got me my first electronic job i watched this video before my interview and they quizzed me on op amps! the luck!
Wow good for you! :) That's so weird. Reminds me of a line from the movie predestination, "luck, is the residue of planning." It's so true. When you work hard for something, luck helps you along the way, more often than not in bad situations. Was that the case with you? Btw I'm in my 3rd year in EE, my school isn't so glorious if u know what I mean. So It's hard trying to become an autodidact, especially with complex matters which don't always have the clear specific explaination on the internet... Sorry for rambling lol
So, do you still have your job Jaguar paw?
@@microdesigns2000 The job this video helped me get was a great place to start I had an excellent mentor there and i worked there for 2 years.
I have since changed employer with a more embedded and programming focus I have been at this subsequent job for 2 years and 2 months now!
Although it was over 4 years ago i still remember the night before the interview trying to cover everyrhing they might ask and watching great videos like this.
@@jaguarpaw1638 That's awesome. I'd love to hear what kind of designs you are working on, without posting anything proprietary.
@@microdesigns2000 I work mainly on low power IoT projects now . I also do home projects too . id like to start my own electronics design business one day!
I find myself revisiting this tutorial as a refresher every time I need to incorporate an OpAmp into one of my projects. Thanks Dave! 👍🏻
Very helpful. I'm an electronics technician and you see this stuff when you're doing repairs or troubleshooting but you never get down to the nitty gritty details especially after 30+ or so years goes by from your initial electronics training so it was really nice of you to explain this especially on layman's terms. Someone else mentioned in this blog about cutting and pasting working circuits into projects and calculating as you went along to fit your needs which is pretty much what I've done in the past so this has really been a BIG help in the memory refresh department. Thank you ten times over and may the "electro" Gods shine good fortune down upon you sir!
I had electronics like a hobby in the secondary school and also the time I was in the university even I've studied mechanics. Great presentation !!
electronic technicians nowdays repair FLAT TVs, monitors, cell phones, install and repair satellite installations, alarm systems, fire detection systems, CCTV installation, PLC programming and maintenance in industrial applications, and a variety of other applications ...
Nowadays, even the electrical appliances of a hotel kitchen may have electronic control boards with fiber optic and internet connectivity.
And in some countries it is not always "throw the old board away and put the new one"
this is the easy way that even a 10 yo child can do.
What if a new electronic board is too expensive ?
Hi dave I've been watching your channel a lot for the last couple years now and it's fantastic! I'm currently doing my honors in electronics engineering and my University here in hamilton New Zealand has instructed my class to watch this video on the current section we are covering on op-amps. You have finally made it to university level teaching my friend!
48:40
Can anybody please tell me the reason of this ?
7 years on and your videos are still helping new technicians. I really appreciate this, thank you.
Watched this 6 years ago as a teenage geek. Learned a lot. Now I rewatch as a 3rd year university student. Still useful. Gonna pass the exam today
Most excellent basic introduction to op-amps I know of. It tells you everything you need to know about fundamental operations of op-amps to get you on your way to understanding more complex circuits.
FINALLY!!!! A video that ACTUALLY EXPLAINS HOW IT WORKS!!!!!
Dave, this video was a godsend.
Regarding the puzzle at the end, the low resistance effect is an increased current at the OA output. the OA at approximately Vout= -0.5V should sink 50uA which is higher than the value in the datasheet/figure13 of 30uA max. so the virtual ground voltage fluctuates and so does the output at approx. -0.5V.
baby...
Thank you.
in the new datasheet, i think its figure 47, that explains this.
@@cireekratz2017
Above explanation said.
at Vout = -0.5V
I sink = 50uA (> 30uA)
Can you please explain me,
What special thing happens at -0.5 V,
Which doesn't happens at other output voltages ?
@@youtubegoogle4163 Hi, the thing is, that this IC has limited current sinking capabilities at low negative output voltages.
In the -0.5V case the sinked current should be (-0.5V/10kOhm) 50 uA. But the IC is not capable to sink that much current at this V_out. Figure 47 in the datasheet shows that it only can handle ~40mA.
Now there are 2 cases:
- slightly higher V_out (like -0.25V): the sink current lowers to 25 uA and that is just in the limit that can be provided (when the supply V difference is at 30V, grey curve) After that the virtual GND can begin to deteriorate.
- lower V_out (like -0.75V): the current sink capability of the IC rises rapidly (after the kink in the curve). It lands around 1.15mA which is sufficient by far.
In the end Dave chose a really nice corner case, where there is only 1 output voltage, where this problem arises. If you lower the R values further, the problem should expand and should arise shortly after V_out = 0V and stretch to around -0.6V.
Hope this helps.
The fact we can learn this and not have to go into debt... your a gift to engineering Dave!
Forget the debt. Being water boarded everyday is not what i would call learning.
@@kevin42 agreed and they inject way too much to do with political issues at times to
Some people really got the "art of sincere teaching". This is the best I've seen so far regarding Op amp basics. God bless you Sir.
Your video is gold. I modeled both inv amp and non-inv amp in LTspice with MAX4352 op-amp. Input voltage: [0,0.5] volts. Vcc:+5v, Vee: GND. Worked perfect. Thanks for your work!
I spent few years in school to learn this (hundreds of years ago) but no teacher was able to present it so clearly like you did - thank you bro
When I learned how to use Op-Amps, the 741 was the state of the art at the time. Yes, had to learn them the hard way back in those days. What a great refresher course for this young man born 9-11-1946. Great job Dave and thank you. Respectfully, Steve
Dave, this is amazing. Thank you for these mini classes, honestly it’s worth more than any electronics class I ever paid for.
Negative feedback op-amps just clicked into place for me about 10 minutes in. I had been struggling with this concept for days. Thank you so much.
You have left a legacy on TH-cam for the coming generations. You are immortal. Salutes.
It's so great to see fellow Australians showing up on TH-cam. Especially for something like explaining electricity. Bringing fame and reputation to our country!
COMPARED TO THE USA, Y'ALL DID NUTTIN SEE---
I am in my senior year for EE and we had a whole 8 weeks in one of my circuit theory classes dedicated solely to op amps. We got to delve deep into these and do some really fun design problems and lab experiments. This video really is a great refresher and good start for anyone new to them.
I wish we had the time for that... I'm in my second year and we spent two days on op amps. This video helped me quite a bit.
I guess we'll return to the op amps later on..
@@TheDaniel85 I am in my junior year, If anything interesting starts, it's going to be in 3rd, 4th year. First two years is just a dull foundation, during a third year pieces of puzzle will be coming together.
Truly one of the best reviews of OP Amps. This validates everything I have learned about OP Amps.
-Thanks
If anyone is interested the gain of the non-inverting config can be derived from the voltage divider equation:
Vin = Vout*R1/(R1+Rf)
Vin/Vout = R1/(R1+Rf)
Vout/Vin = (R1+Rf)/R1
Vout/Vin = 1+Rf/R1
And the gain of the inverting config can be found from the currents:
I(Rf) = Vout/Rf
I(R1) = -Vin/R1
-> Current through both resistors is equal so...
-Vin/R1 = Vout/Rf
Vout/Vin = -Rf/R1
:)
Amazing how simple the above is when you can assume that the internal gain of the opamp is infinite. Everyone going through EE should be able to demonstrate the above in the time it takes to write it down. Well done.
Here Vin1=Vin2 due to the virtual short between the input terminals, if anyone had a doubt
Thank you so much for this! Not as bad as I thought coming into this! Matter-in-fact, really fun!!!!!!!!!!!! :DDDDDDDDDDD ♡
One of the most sensible ways of explaining the basics of op amps. Great work Dave
This video got me a job as a tech earlier this year. I spent so much time reading different articles about it and struggled to wrap my head around it. In the interview they had a worksheet with ohms law voltage divers etc and then in the verbal portion he brought up op amps. I just started talking and after a bit he smiled and I knew I was hired. Thanks Dave!
Excellent discussion. Takes me back 35 years to my intro to op-amps. My professor explained what was to us an amazing and confusion subject just as you did and within a day or so we couldn't wait for the lab. I'm now hooked on your channel. atb Opal
Read this after 12:23 and listen to buffer amplifier again.
The primary objective of buffer circuit is to boost the current in any circuit at any stage. Buffer circuits are mainly used where a signal has very low current input(high input impedance) which needs to be increased maintaining the same voltage levels. So, this buffer circuits draws current from power source and adds it to the signal.
Buffer amp is also called as voltage follower or unity gain amplifier . Hope this makes sense now !
This explanation is superb! It is THE best I've ever seen from any book or professor. Truly, a gold nugget.
If my college lecturer in the 1970s in England had been just half as good as explaining things as you, I could have saved myself 40 years of stress thinking that I was an idiot. Keep up the excellent work, you obviously love passing on your knowledge and are brilliant at doing it. I am now totaly gripped.
as an electrical engineering student, this channel is priceless. thank you for this channel and to so many other folks who do the same...
Thanks for doing teaching vids, Dave! I took many electrical engineering courses in college and we did a lot with op-amps, but I'm embarrassed to admit I've completely forgotten everything about them since then. These practical introduction videos are perfect for people like me who want to reconnect to something we learned in the past. Thanks again!
If only I had the opportunity to watch this when I was learning about OpAmps some decades ago ! So much simpler to understand with you, Dave !
Thumbs-up for the vid on properly terminating op-amps please Dave ;)
i agree too!
e2e.ti.com/blogs_/archives/b/thesignal/archive/2012/11/27/the-unused-op-amp-what-to-do - found this today on TI's website
Someone in my class has been spreading around this video to everyone and they're all raving about how useful your video is.
Thanks to you, and your videos I am today a successful engineer working in semiconductor industry. I am just coming back, years after I watched this video for the first time. I was having problems passing the only one remaining subject to get my degree and was searching for a helpful video on opamps. Not only you helped me, but also inspired me with your positive personality! Keep up the good work!
You are really great at this. I'm in a 3rd semester EET student and I learned a thing or two about op-amps from you. I should be paying you tuition!
Well, I secured more marks than my friends in our exam just by watching this video 2 hour prior to my exam. Thanks Dave.
i'm literally crying, thank you so much. my physics midterm is tomorrow and i truly thought i was screwed. but now i think i can save my grade, subscribed x
How did you do on your midterm?? This stuff is not easy so don't give up!
This video literaly saved me :), right now in the university everything is going on-line and some teacher are just an assholes that don't care if we are learning with this new method and I mean, there is this one teacher that literaly send us to read a book and that´s it, nothing more, and well, I think this is the best class about op amps I have right now. Thank you so much
tonight i learned 10x more about op-amps, and with a deeper understanding, than
i did in a whole semester in a suffocating classroom. Thank you for your time.
What the hell just happened? I felt like I had watched a 10 min video. By the time I looked at the time line, 49 minutes had already passed. Magic OOOOoooooo. XD
Wow, huge thanks for a crystal clear explaination! I have watched several other videos where others tried to show how awesome opamps are and after those videos I became more confused. At last, thanks to your awesome video I understand what it is and how I can use them. Awesome Dave, it´s like christmas following your videos.
i always catch myself smiling while watching this guy
We're moving into Op-Amps in my 2nd year circuits class, and I've already gone through 3 shorter "intro to op amps / op amp basics" videos with high view counts and all of them were rubbish in terms of being "basic introductions". This 50 minute video is already vastly superior in presenting the fundamentals clearly and simply in the first 5 minutes. Happy to have found it!
Even after 30 years away from electronics I got the gist of you lesson, thanks you explain it very well and in manner I just love. I worked in the dept of Navy as a trainee and we had two parts, one was a TAFE course the other was direct from Naval lecturers. The naval lecturers were like you extremely conversant and able to explain in a much more understandable manner.
I have been watching this as a kid and now it feels so nostalgic after i have passed my electronics engineering school , it really so nostalgic
Love these. More, please. I've been using Op Amps and Comparators for decades and still learned a couple tricks watching this video!
The concept of virtual ground was delivered precisely.
Thank you Dave!!!!
yep. he nailed it
This brings back memories. I learned all this in studying for by BSEE degree that I got in 1976.
I have no idea why TH-cam sent me here. The last video I watched was on modeling an MOV surge protector in LTSpice. I dozed off and wound up here.
Back in 1976 we had a saying:
*_”Four years ago I couldn’t spell ‘injuneer’ and now I are one!”_*
Dave, though i've never met you or even had a two-way communication with you i do see you as my friend and tutor. Maybe it's simply because you come across as a really nice guy in your vblog, and i've seen so much of your face and so much appreciate your educational skills. Maybe it's becuse with you as my major source of education i've had the best grades in every course i've taken over the last 18 months, spending close to no time at all studying, giving me time to earn some well needed cash for equipment, working as a private tutor for other students, and that was not even deliberate. I was approached by peers who wanted tutoring and insisted on paying me for it, reasoning that their parents were prepared to pay the tripple amount to an actual professor who would no likely be any better than any of our own teachers, working out of the same curriculum, and that they knew from class that they understood me way better than any teacher.
Because every teacher we've ever had can take hours trying to explain these concepts to no avail, but using sometimes slightly modified (just enough to fit exactly the concept we're studying and the specific questions the sometimes slighly slow teacher wants answered at that moment) versions of what you've taught me i can explain concepts so that my peers understand them well enough to get at least a C in a matter of a few sentences. No matter what knowledge gaps my teachers have left behind i can fill them in, in a matter of minutes and almost never having to explain something twice to anyone, ever, using your pedagogic models! 9/10 times when i explain something the answer is something like "Ahaaa! Oh my god i feel so dumb, it's not even that complicated!"
A lot of people don't appeciate the fact that the ability to understand something better than others, doesn't magically give you the ability to describe it in a way so that those that don't understand it can also do so! It's not just that i have complete confidence in the quality of the information you provide, it's your ability to explain thing that would have taken me hours or days to figure out, if at all, in a matter of seconds or minutes. In fact the service you provide me, absolutely for free, saves me so much time (generally in between 10-20 hours a week in school. Is this even real?!!!!! o____0 ) since i don't have to study anymore to get top grades and not be the teacher's pet but rather his assistant! So... The fact of the matter Dave, is that i basically owe you roughly 17% of my total spare time, weekends included! Those are 17% of the part of my life that i get to spend as my heart desires. And i simply just can't thank you for that in writing, because whatever words i chose would be an insult to your genius! But still, i do have to say something so a simpler thank you will have to suffice.
Thank you professor Dave, thank you so very very much! The quality of the service you provide is in my experience unprecedented in any and all forums from the web to actual traditional education in a "real" school. I hope that you love doing what you're doing as much as i love watching you do it, and that you will keep doing this for a long, long time!
Your devoted fan and pupil,
Fredrik Sjöblom,
Stockholm, Sweden.
Excellent video Dave!
Concerning the puzzle on the end. I think it's the reduced current sinking capabilities of the LM358 when Vout is small in respect to ground. If look up the "Output Characteristics Current Sinking" graph in the datasheet you can see that the LM358 can sink very little current at low output voltages. As you have a 1k R1 and 2Vpp input voltage you have 2mApp of current, which is still too much to sink for the LM358 at low output voltages. So the LM358 can't keep the virtual ground equal with the "real" ground trough it's FB network. Therefore you get those spikes and the sagging and rising of the virtual ground in between.
Nice work! I noticed that all datasheets doesnt show this. The Motorola version did not so that might be an extra "trap for young players"
That´s it, exatcly :)
You are right, just a small clarification. the OA at Vout= -0.5V should sink 50uA which is higher than the value in the datasheet/figure13 of 30uA max. so the virtual ground voltage fluctuates and so does the output at approx. -0.5V.
+TheElectr0nicus but why does it jump like that? And why is there such a weird knee in the sink around that voltage (i.e. the physical reason for the fact that it goes closer to linear at even lower voltages)
I love you. You should have been my EE professor for every class at my uni
+Edith Mejia wow. i would have thought that your school had good professors!
+Edith Mejia what would be the fun in that? Don't you enjoy not understanding something and then spending hours online looking for information...for free? I know I do! (that's a lie)
aww wook at the wittle fluffy headed female. it's thinks it knows how electronics works
You have to be kidding mate.
Joseph Beasley Mmmm deep male insecurity, pretty embarrassing comment there. I'm not sure you understand how insecure this makes you look.
Great explanations. I used OpAmps before, but more copy-and-paste style, just using the standard circuits without thinking about it. Now it makes sense why it works, and with the two rules I might even create equations to analyze more complex circuits, like the differential amplifier, where you've lost me a bit.
Yeah, I did gloss over the differential amplifier a bit, sorry about that.
Gloss? Yeah I totally missed Diff Amp totally. You probably used initials DA and it just didn't register in my mind.
I'm not sure what the issue is. Analyze it like any other inverting amp. The voltage at the inverting input sets the voltage at the non-inverting input: 0.91091V. The voltage drop through the inverting R1 1K resistor is 1.1V - 0.91091V, or 0.1909V. The current through the inverting R1 and sunk by this inverting op amp through the feedback circuit is 0.19091V / 1K, or 0.1909 mA. The voltage drop across the feedback resistor R2 is 0.1909 mA x 10K, or 1.9V. The voltage at the op-amp's output is the voltage at the inverting input less the voltage drop of the feedback resistor, R2: 0.9191V - 1.9V, or about -1V. As a check. the voltage gain formula is -R2/R1, or -10K/1K = -10. The difference in voltage at the inverting and non-inverting inputs is 0.1V. So, the op-amp's output using the gain formula is .1V X -10, or -1V.
You are a brilliant teacher. Your ability to explain these concepts in an easily understood and straightforward way is a precious gift. I say this as someone who, many many decades ago, struggled as a student trying to understand so many instructors who did not have the ability to convey their knowledge to their students.
Took years to comprehend this stuff. Especially when it came to more complex circuitry and control of DC motors from controlling speed, current, volts, positioning, etc. Great video and spot on! Thanks
Back in May of 1978 I started work at an aerospace company that made the engine controllers for a military jet aircraft. The engine controller was a low frequency (less than 10 KHz) precision analogue computer that had amplifier gains & offsets calibrated to +/- 2 mV with select on test 1% tolerance resistors. Some critical circuits in the controller used 0.1% tolerance resistors. Positive 10 V and negative 10 V references were used throughout, and as well as the usual feedback loop components there were two 10.6 V Zener diodes in each loop. All of the virtual earths were connected to a virtual earth monitor that used a high gain amplifier to indicate any opamp failures. After a few years the engine controller was redesigned around 12 MHz 16 bit microprocessors and was considered to be not as good as the analogue version because at full speed the aircraft would travel about 50 feet before the software loop was reiterated.
Some of the circuitry in the analogue version was very unusual and complex and I learned a lot about circuit design with opamps. It was a great place to work because there were occasions when batches of high grade components were thrown into a skip, and the company didn't care where they went. To this day I have a huge stock of mostly obsolete but still useful components that I use for making projects and stuff that can't be purchased off the shelf.
Thanks for the video.
so was the processor just running at too low frequency? also what did the engine controller do/was used for?
Yeah!
perfect explanation about virtual ground.
Thanks Dave!
Patrick Franco Bello Thanks, glad you liked it.
@@EEVblog Thanks
This video made everyone think I'm a genius when we were taught this in class!
Simply 💯 percent on target
And here I am looking at it at 5am when I have a quiz over ideal and non ideal opamps at 9am
👍
It's amazing how bored teachers can make something not that complicated look like a mountain.. I never ever understood opamps at school, and after a fews minutes in now, i'm like... How the hell did they manage to overcomplicate that???
@@usoppbarbosa981 is it because they don't have practical design experience??...
I studied and played around with this stuff over 40 years ago, it's quite refreshing watching these videos.
I went into digital for many years practically ignoring analog.
Thank you Dave.
This is probably the most comprehensive and effective explanation I've ever watched about opamps. You sir are a pedagogical genius!
Great explanation, you just took the best OP-Amp explanation until now from:YT- John Santiago Op Amp Design Basics - Inverting Amplifier - Part 3
(i was actually wondering when you will do that 8-).
While you mentioned ohm's law you might add Kirchhoff circuit law in the part where you "wonder" about where current goes and that lack of minus in inv. OP gain formula was bugging me until you corrected it...
For the end, you put smaller resistor which drives 10x larger current form output trough feedback resistor to "match/counter" input current (100uAmpsp rise into 1mAp) so output stage switches into B class (whole chip with 2xOPAmps has less then 1mA quiescent current and output stage probably uses about 70% of that) and you see clear crossover distortion on the output waveform (where OP-Amp loses control hence the spikes on the input, you can represent that as vehicle steering wheel dead play for mechanical types)
Great video, just took best opamp explanation title,cant wait for #2,3,....
Hi Dave,
Please do a video on how to terminate OP-AMP, it's an important topic as well.
Good job, thank you.
Yes for an op-amp terminating video.
Ohmygosh, is that really it? You just compressed my college circuits II class into a 50 minute video! Thanks for the simplification!
this video (as old as it is) really helped my early on while studying my degree, then even now years later i watched it day before i went into the job interview of my dreams, and it may well have been the contributing factor that landed me the job. so a huuuuge thanks.
This was the Video that made me fall in love with electronics!
What an awesome tutorial !!
This is the best explanation I've seen on the virtual ground. Nice!
P.S: Next time, please consider giving an intro to DSPs, would be awesome!
Happy 600th EEVBlog Dave!
You have succeeded where hours of instruction and study have failed: making me understand how opamps work. I am unable to express my gratitude.
unbelievable, what a master class. this teacher deserves his salary. I honestly want to make a donation. you made my day. I never laughed so much in class as I did in this video with you!! :)) he does not only explain it amazingly well, but also makes it entertaining. 10 points
good ol crossover-distortion. the LM358 has a class-B output stage and has to be biased properly or you get crossover distortion. instead of having diodes in the output stage, they tied the bases together. They were designed to be low power, so they did this. a proper load resistor between the output and negative supply will fix this problem. decreasing the feedback resistors increase the load by decreasing the overall impedance to the "virtual-ground", causing more and more crossover distortion.
There is a tradeoff, by putting a resistor in the output stage to -ve, you also get a much higher idle current. Much more than of a standard class-ab op-amp. So that blows the "low-power" rating into the rubbish bin.
Edited as my first couple attempts didnt sound, or come out right.
Yeah, found that explanation in about ten places on the net, none of them bothered to explain how the missing load resistor influences anything - they all went way, way above the 'dummie level' this video is addressing (and most certainly outside its scope). Kind of like the answer above, actually. Would you please elaborate a bit on that - I freely admit to being a proper dummy in any of this analog stuff...?
Attila Asztalos Im going to leave that one to Dave as he is going to explain it better than I ever would. From what I understood years ago, is there is a small current source in the IC that needs beefed up by the resistor to bias the output stage into conduction on both transistors instead of just one. its class-B for a reason, one is because its low power, 2 is because it can reach ground whereas true class-AB cannot, at least not without some help. Amplifier classes are explained on the web in various places, but class B means its biased into cutoff. Meaning at idle with no signal present, the transistor is switched off. Raising the input voltage approximately 0.7V into forward-bias, the transistors will begin to turn on. When the output signal reverses below 0.7v, the transistor is off. Then as it swings below 0, into -0.7v then it will switch on again. (lower transistor). That creates a dead-zone of approximately 1.4v that the amplifier isnt conducting. This creates crossover distortion. The external resistor increases the source current to the bias network, adding extra idle voltage/current into the output stage allowing the transistors to stay on all the time, known as class AB, or for some reason in the LM358's case, Class-A.
Edit: Looked at the datasheet, the texas instruments datasheet on page 11 explains it all.
Nice.
th-cam.com/video/VgodYtiD_F0/w-d-xo.html
For the love of Tesla, I was so friggin' nervous when you forgot the 'negative' of inverting gain!
And now we need a second part, where you show us the non-common circuits, as let say...Gyrator-stuff, Log-converters, average/peak rectifiers, and "interferences" when using OpAmps in RF circuits (like input pin reversion)....;)
was'nt too sure at first about the teaching style but after a few moments. lights were going grower much brighter! you never really lost a monent. very nicely articulated tutorial of an Opp. Amp. specialy as a refresher. since it's been 20 years practiculy. very nice ,will be following up . good work , can tell you love it bravo!!!
I was am A student in my EET school and did great w the math, understood digit TTL.... But when we got to analog chips like the Op Amp, I just couldn't grasp it w a gut intuition, and started to get behind the instructor, constantly playing catchup. I didn't have problems w the math, but since I didn't have that intuition I was just plugging in numbers and not understanding the fundamentals. I had no idea what the 741 was able to do, what it was for, and completely flummoxed when the amplifier circuits were combined w other chips and components.
When Dave started out by erasing that scary looking circuit and the math, I was like, ah ha! His method of starting w the basics got me thinking after 30 years, I'm finally gonna be able to comprehend this! For years, I was so intimidated by the 741 that I'd quickly become discouraged when circuits had them and I'd just give up and would just mindlessly follow the schematic and solder em in. Those days are coming to an end.
Thanks, Dave. If it weren't for Dave TV, grasping this would be a whole lot harder. Stand aside, Mr 741 Op Amp!
This guy taught me what I couldn't understand in my class even after discussing with 3 professors😂😂
Same bro
I was just thinking the same thinking I wish my college professor explained it like this...or maybe I was just too hung over to understand :-)
That's because he has designed so much own circuits
Was a professional electronic designer
Invented 32 channel logic analyser in the 80s
Played with lot of op amps and some professors have never used a 741
Your professors probably don't understand it either, so tell them to watch this video ;)
I spent 10 minutes waiting to see a correction for the inverting op amp, didn't want to comment too soon but finally my mind is at rest :)
Would you believe me if I said it was a deliberate test?
Probably not, but hearYe hearYe, spoiler alert.
Thank you Dave! This video has saved me headaches on multiple occasions. Everything is so well explained. I keep coming back to it for reference.
Whatever haven't tought for x amount of reasons eg lack of access to higher education, means of funds, have a chance to broaden my knowledge and horizons thanks to you and a few other persons like you. A huge thank you is certainly not enough.
LOrd! Where do I start. This is the best tutorial I've ever experienced. You literally just saved me failure in less than an hour while other lectures are taking entire semesters to attempt doing so and still failing. THANK YOU!
I wish you could do one like this for transistors!
Transistors are even simpler
@@thatcrazywolf
You mean what type exactly? 😂😂
MOSFET ?
BJT ?
IGBT ?
Under BJT
PNP or NPN?
Under MOSFET
Depletion or enhancement type?
All I mean is really??? 😂
Hey Dave, can your next video be on the stuff you crossed out? I wanted to cry there for a sec. There are tons and tons of resources about the basics of op amps, there a dime a dozen. However, there are very very few complete videos on op amp internals. Finding videos on the basics is utterly simple but finding well presented videos on more advance material such as op amp internals is painfully difficult.
Agreed! It (almost) always helps, after learning the basics, to learn how they physically work inside to really cement the concepts in your brain!
You just solved my question for a project.. there we go.. another step forward.
This video contains more information than half of semester of electronics on my university and thanks to it I have maxed one of two tests required to complete the course in about 20 minutes
@@lepidoptera9337 Nah, I study informatics and electronics by itself is just kind of filler subject and they put more pressure on other stuff
Dude, best explanation of opamps I've ever heard! My professor in college back in the day was an asshole, making this so complicated.
OMG THANKS SO MUCH!! T^T You just saved my exams:')
The things that were written on the board at the starting is exactly what my university wants me to learn
i never even gain 10% of knowledge i got here on opamps from those electronic classes back then on the 741
excellent tutorial
Excellent teacher - one of a kind.
The teachers have to include all of the unnecessary theory involved as if there is no IC, but we can't repair the IC, only replace it and you're starting from scratch which is not needed unless you plan to make your own IC and half of these teachers speak in monotone and barely grasp what they're reading so when you ask certain questions they will look it up and attempt to explain, but there are the exceptional that really know and they have a way to explain because they have the full understanding.
Pun intended?
BINGO!!!! Suddenly it came clear at about 10:00 how simple it is to use these devices! I have a compartment in my component collection of OpAmps that I purchased for a device I needed to build, and as you know, you can hardly buy just one, so, of course, I purchased 10, and promptly forgot what I purchased them for, because the order came in from China about 35 days after I placed it, and the notion of what I was building had been replaced by something else completely, so I have all these OpAmps and nothing to do with them. Thankfully I came across your video, so I may well begin to play with them when I get back from our Winter quarters in Arizona and return to my home in South Dakota, where they are under a full fledged blizzard warning as I type, and here in Arizona, we are under a wind warning with the temps at 65 degrees F. Oh what a difference some 1500 miles can make!
I have a question in my head and two minutes later you answer it. What a legend..
Thanks for all you do.