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Hey Dave! I don't know if you check comments on old videos but I wanted to mention some things from my experience at work building amplifiers for signals in the 50nV range. Based on Jim Williams' work, I started using steel cans for my testing. I put my little amplifiers into Altoids mint cans with a voltage divider built-in so I can inject a signal and I have no problems with 60Hz (USA) mains frequency showing up in my measurements. A 9v battery and the amp fit nicely, and I can solder directly to the tin for a solid ground. I have found that die cast and aluminum boxes don't work as well as steel mint or and cookie tins. Ferrous material really helps with shielding! I have been able to show a 100nV signal on the DSA at work with no trouble! Also, I use an HP DSA for spot checks but final plots are done with an RME audio interface and Matlab, which easily beats the HP signal-noise specs. Thanks, and keep up the good work!

I was thinking of a follow up video that would take into account the gain resistor noise and input current noise as well. But nothing beyond that.

Even though I don't suppose I'll ever use this information, I find it highly interesting. You have quite a nice way of explaining things. Speaking of noise, perhaps an upcoming video could explain the different types of noise you mentioned at 13:00. Something of a comparison of each type, how they are generated, and how different components (resistor vs. cap vs. inductor vs. transistor etc.) are affected by the different noise profiles. Maybe even techniques to deal with the different types.

Good video. I love the fundamentals videos. Please don't stop doing them, there's not enough educational content on the you toobs.

Try the automatic subtitling (right lower corner of videoplayer frame). Works!

Loved the video ! Thank you for this.

Actually it possible to measure the noise of an op amp with only 10nv/rtHz if your op-amp have some gain. For example, if your op-amp have a gain of 10, at the ouput, the noise will be arroud 100nv/rtHz ! Because this is the noise defined to the input of the op-amp and it will be amplified by the op-amp.

More Fundamentals like this! Less Fundamental, more intermediate.

I'd love to see the old 741 here. :)

Can we say that nV/sqrt(Hz) is basically the power spectral density. If we sqr() this we get W/Hz over 1ohm resistor.

This video is excellent Dave. Don't be fooled by the apparent little interest of the people who don't get it yet. We want the followup :-) Thanks a lot.

Johnson noise is recognisable as a 'fap, fap, fap' sound and is often a problem with teenage op-amps.

Two years ago I watched your OpAmps tutorial video as a 2nd year B.Sc. student preparing for his Electronics class exam. Now I'm working on my B.Sc. thesis and again hats off to your great explanation sir!

I'd like to see that opamp upgrade video.

Speaking as a physicist (to be, at least), I have the urge to add another clarification to the video. Namely: physics ALWAYS makes sense - it is, however, sometimes counterintuitive. There's a huge difference. Great video though, thanks Dave

Hey Dave, I've been sick for the last few days and I think I might have spent about 90% of my waking time watching your videos, please keep them up they're brilliant :)

Love your videos. Very helpful

I'm not going to spend several hours extra per video to add subtitles for the few people that would make use of it. That could be more time than I spend shooting or editing. For someone else you would have to find someone technically competent that knows the lingo, plus the aussie slang etc. And is it worth spending the money on that for a few people that might use it anyway? Sorry, but I don't think so. Same goes for other languages.

Dear Dave, what about transistor noise? I have opened BC547 datasheet and see Noise Figure in dB. How to match it to Volts? P.S. I think I found the answer. Decibels express ratio between "real" noise of transistor, OA or anyone else to ideal thermal noise of a resistor. Am I right? Anyone answer me please!

I would never take it to the bank! I recon I make some sort of mistake or slip of the tounge in most videos. I did in this one, hence a few annotations. The off-the-cuff nature and the difficultly of checking ones own work during editing means mistakes will always slip through.

Shouldn't the noise density translate to something like e=u/sqB, where e=10nV/sqHz, which comes down to u=e*sqB, instead of the rather confusing explanation you gave. (u is noise, B is bandwidth)

Now I think I see why the DSA had all that shielding.

Do you mean inverting and non-inverting configurations? If so, the answer is no, it's the same. You don't use positive feedback for amplifiers.

Uncle Bob would put in screws to lock the box. 😎

Great video. You answered so many questions I had about my HP3562A analyzer. I would love to see you make video about dropping in the high performance modern lower noise parts in it. And then see you go through calibration. It would be a great video mate!

How do you reduce it? I have a noisy SE1000A Mic producing allot of white noise Hummm. Any ideas? Can I install a trim pott to balance the rails?]

I used to have an Ono Sokki. Don't recall the exact model though, but it wasn't that one, much older.

Excellent presentation! I do have a couple of questions, however (warning: long post): why doesn't the DSA use its own calibration data to remove its average noise contribution from the display? Much like 'taring' a scale? The math is straightforward enough as demonstrated by your own calculations at the cursor frequency and SO shouldn't be all that taxing to the analyser's CPU, so why doesn't the DSA do that for you at all the points? That would be very convenient, yes? My second question is: why does the displayed 1/f frequency curve taper-off at the lowest frequencies instead of increasing with decreasing frequency as all 1/f curves do? Surely this is an artifact? Even with _two_ data points it should sweep much higher than seen on this video (as at f = 0 Hz it is theoretically _infinite_ [but would take an infinite time to measure] :). Is the DSA bandwidth-limited at that end even with DC coupling, and even though it is spec'd from _DC_ to ~100 kHz? And just a note: coax shields are generally pretty good as _electrostatic_ shields, but not so great where _near field inductive_ coupling is concerned, where there's a measurable AC _magnetic_ field gradient penetrating the shield into the space between shield and the centre conductor? Same for die-cast aluminium boxes. Possibly a good mu-metal enclosure (at least for the DUT and wiring), may reduce that 50 Hz peak somewhat? Give it a try and see if it makes a difference. Mains frequencies (and harmonics) are the bane of my applications, VLF/ULF/ELF radio receivers. The one I'm designing at the moment has a passband beginning well inside that 1/f curve, with the upper stopband beginning at around 40 Hz. Even so, 50 & 60 Hz mains frequencies can be strong enough to swamp the preamp and it is nearly impossible, it seems, to get away from it - short of moving to _Antarctica._ :( As far as 1/f specs go, in your experience which COTS high GBP, low-noise op-amps would you recommend for the best 1/f performance? Currently I'm using the LT1028, mainly because I have some left over from an earlier, higher frequency (tho

The thought never crossed my mind! :->

There are many sources to consider if you want to do this properly, I just wanted to do a quick test to see if I could show the difference between opamps. This is ballpark stuff.

The drawing on the board is incorrect, the noise result is not 316 nV RMS but 48 nV rms and 316 nVpp. The datasheet figures are full noise voltage density not RMS density. Noise current flows out of the opamp not in and causes additional noise voltage on Input resistance on each pin (V- and V+). And some more issues, so be careful...

Trying to figure out how nV/RootHz was derived. Seems like it came from spectral energy density maybe? V^2/Hz .. Ok, turns out I was right. Some explanation here: electronics.stackexchange.com/questions/32257/noise-and-what-does-v-%E2%88%9Ahz-actually-mean .

I suggest you to watch the whole EEVblog video saga, after listening to the 527 videos you'll understand him perfectly ;)

The video is already uploaded, but it's just me taking the lid off and looking at the devices.

Sorry, but they are incredibly time intensive to produce, or very expensive to have someone do for me.

It generally takes well under an hour. I can literally watch the counter increment on every page refresh. And it usually takes less than a minute after release for someone to comment!

It wouldn't be huge, you are still stuck with the small dynamic range.

Why don't we use 100Mohm resistors on our Opamp voltage dividers? I always see things like 47kohm.

thank you for your work, dave. you have truly made me more interesteed

The more I learn about precision electronics, the less I am able to sleep at night after completing a project.

"Input referred" is actually rather important. Without saying referred you could be saying the op-amp puts that noise on the input signal, instead of the real meaning, which is noise at the output multiplied by the gain in between input and output.

So, the elephant in the room. What happens to the noise values at DC? I want to build a low noise instrument to measure DC to 10Hz. How do I know the noise value at DC?

What mean by jellybean??😬

Dave, make another power supply video :)

Very good explanation! It was a good help ;). I need to amplify the output voltage of a 1kHz notch filter, uVs... to measure a SINAD in an audio Amplifier. But I'm having troubles with the noise. Now I'll try reduce the resistors values and chose an op-amp with a reduced noise, now the ne5532... Many thanks! My Channel is in Portuguese sorry... Regards, Hugo.

Very informative indeed. I've learnt a few things. Thanks.

Science should create the first noiseless opamp. By injecting anti noise (at quantum noise level) to cancel out the fundamental noise of the thing. Science should push electronics to near ideal.

When changing the vertical axis, Dave used the non RMS option (with the RMS option being one option lower). On the whiteboard he said it was all RMS like the 316nV result. Is one of these two things a mistake? Someone else said 316nV was the p-p figure. Can anyone else confirm/explain, pls?

Great old video Dave, after watching one of your videos years ago about the HP DSA I was able to find one at some government auction, GLAD I did ! Wish you would do some more vids using these ol boat anchors.

Thanks Dave. I learned a lot. Another great video.

So...,I'm closed at home because of coronavirus in Spain at the order from our goverment. But, with gems to learn like your videos, i hope not to be bored much next two weeks. Thanks for this videos Dave!.

Hello! I have a question and I cannot find the answer anywhere in the internet. My professor uses a complicated approach regarding the calculation of an output rms noise in a OpAmp. He says we must calculate the transfer function of the circuit several times applying a voltage noise as a voltage generator at the OpAmp + terminal and applying 2 current generator at + and - terminals. After this we must integrate the squared modulus of the transfer function multiplied by the power spectral density (PSD), which is usually a known quantity. Then we must calculate the result of this integral, but crazy things happen! He starts considering the loop gain, the ideal gain and the real closed loop gain and after making some consideration about that, he finds some bandwidth where the noise is relevant and multiplies it by a pi/2 factor. Do you have an idea about how this is done? And which consideration I have to do about all these gains to find the rms noise? Or any reference (like books) I can look at?

sjekk out a real low noise riaa stage made in 1995 kofigured in a unusual way opa ad742 10 times amp into ad 844 40 times amplification.you can read about it on different cites.lc audio have a english site to. pr channel and a stereo buffer?lf412.later they made use of lf411 mono buffer pr channel before output.it is a no negative feedback local or global design.and it is smart implemented for superb result.the best riaa i ever built.My power amplifiers are also no negative feeback and they sound more natural down in the lower vocal range and the dont change caracter after hwen i turn up the the autenator on my benchmark dac/modified.a piece of gear like bencmark boust about analog volum and it is the cheapest smallest crap potentiometers i have seen.i they never last more than 2 years.so i change out to 21 step wishay dale resistor based autenator same value 10kohm.they are small and are made with different curves.i gota speacial hifi grade curve they called it from laser collection on ebay.they are very good.i have bougth several since and upgraded my old elektrostatic stax head speaker amplifier with the same 10kohm and curve as the one used in my dac.very pleased.no pops or kliks when turing the autenator. a cheap way to get a real upgrade volum control and sound quality.and it is reliable.i have inpected how they are build.and they seem very ok to me.

Why is input noise divide by the gain rather than multiplied?

Mega ah-ha moment for the youngster engineers @6:20.

2 mins in and I'm completely lost. Sounds like a really good video though ;)

Why is the 50Hz noise if it is totally shielded?

Thank you so much for these op-amp tutorials. I have been building circuits using op amps my entire life, and I never had a true ( thorough) understanding of how they work and how to design circuits with them- until now, seeing your videos. Thanks again.

Do people really charge that much??? It can't be that hard, it only takes me about 2-3x real time, and less once one got used to it... hrmmm

I like the australian accent! =)

Loved how you dropped in the 5534 in the end. Millions of those and millions of TLO72/3/4 in audio products over the decades.

The answer is correct.

Using the division sign for multiplication is the most engineer thing I've ever seen.

Im just getting started with this subject. Im confused, how does 10nV*(sqrt(10,000)) equal 318nV Im sure Im missing something in the material....Thanks for any help...awesome videos by the way..love them all

Thanks a lot....we're learning this in our masters and your explanation is better!!

Would like that. Some practical real world advice for low noise audio. Where using a metal film resistor makes a difference and why, etc.

In case anyone else goes looking, the component Dave used at the end is the NE5534, not "NA5534". I have a hard time distinguishing his As from his Es. I first heard Dave on the AMP Hour podcast, and for quite some time I thought he wrote the AAV Blog.

These videos make the subject much easier to understand by combining theory with experiments. Thank you !

Excellent. Clarified many questions on Op Amp noise. Thanks.

I am surprised because Dave produces a very clear audio. I recommend to use headphones. It helps me sometimes. Not that I ever needed them on one of the EEVBlogs.

god damnit Dave its 4:35am here and you always have to upload a video to keep me awake until the sun rises

Are you sure that the dsa is calibrated? In feature you'll do a teardown of the unit or pheraps, if needed, a calibration of the unit?

Can't you use the opamp itself to amplify the referred input noise for measurement, at least to the correct order? You alluded to the fact that this is possible in the video, I think it should work for measuring the amp too, shouldn't it?

Epic!

Really nice video and good old intrument there.. One thing you could have shown was the effect of the cable+box without any opamp active. That could give better base level for testing the opamps instead of direct 50ohms termnation.

Great videos very helpful and informative what op-amp would you recommend for a stereo low THD audio differential amp circuit for converting balanced audio into unbalanced. i need an entry differential amp for a TDA2822 based headphone amp i am building

So it's better to use AC if you wanna amplify the microvolts from a thermocouple?

This video should be named "Dave finds a reason to play with his new toy" hah. Keep'em coming!

What's the oscilloscope volts hrts faze wave with the least resistance to nitrogen triple bond at 14.7 psi in a double tesla coil with tazor tips electric field?

Excellent post. Many of the terms used in datasheets aren't obvious and I appreciate you taking the time to make some sense of the more obscure ones that I may incorrectly gloss over when selecting components.

I'm really looking forward to see the "optimizing the 35660A with modern input opamps"-video! I hope i''m not alone! =) btw... i really liked the whole tutorial, it gave me much new knowledge about op's! Thank you!

The reason I love this channel, is that you can take everything that comes out of Dave's mouth to the bank. Too many people try to bullshit their way through a video like this. Great video!

place the box in freezer, lets see if PSD level goes down :P

Interesting!

This video couldn't have come at a better time for me Dave! Thanks. FWIW, last year researchers used layered graphene to determine that "1/f noise becomes dominated by the volume noise when the thickness of the films exceeds ∼7 atomic layers (which corresponds to ∼2.5 nm). The 1/f noise is the pure surface phenomenon below this thickness." [arXiv:1211.5155]

Agreed, still waiting for the FPGA tutorial..Thumbs up anyway Thanks.

Cool Stuff this time, Dave...! Noise is very complicated stuff, a whole lecture of my EE-studies only covered the noise. What i still do not understand is, why nearly all "HiFi" companies still using crap&cheap carbon film resistors with respect to the noise...;)

I was hoping you would show the difference with the lid off the box. Thanks

Another superb video. I can't wait for the 35660A upgrade video.

lets talk quantum mechanics vs. theory of relativity :P

Nearly to the 301+ threshold in under an hour. You're pretty popular Dave!

nice tutorial, but where are fpga tutorials?? :)

Is the current input noise related to the voltage input noise?

Excellent tutorial.

That was such a fun vid! I learned a lot, and I loved that you used the DSA we had fun watching you troubleshoot and repair. You'd make a fun character if there was ever going to be another Mad Max film (one of my favorite movie franchises, btw).

50Hz pick up is usually from the AC mains !

great vid. thanks

Guys, im not english and I don't know what "jellybean" means in that sentence: "it's one of jellybean precision devices" can someone explain? I know what jellybean is, but not in this context :)

Love fundamental Fridays, I always learn something new. The subjects are practical and your explanations are always very understandable. Thanks!

What is Jelly Bean Precision?