EEVblog 1473 - How Your LCR Meter Works
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- เผยแพร่เมื่อ 15 มิ.ย. 2024
- How an LCR meter works.
Part 2: In-circuit bench testing video: • EEVblog 1474 - Can You...
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#ElectronicsCreators #LCR #Tutorial - วิทยาศาสตร์และเทคโนโลยี
A little correction.
At the bottom right on the whiteboard, you have ...
D = |Rs| / Xs
... it should be ...
D = Rs / |Xs|
... as Xs is the value that can be negative.
Err, yeah, that sounds more righter...
@@EEVblog Nay mate, the original was good enough for Hostralia...
And the red Xs in the bottom center diagram would be better placed on the imaginary axis, similar to the Rs on the real axis (or replaced by "Zs" instead). Great video nevertheless!
It is the same. It does not matter if you multiply something with -1 or dividing something with -1. It does not matter if the - sign is over or under, because it is the same. There is not "righter" :)
@@zsoltkohler7096 you're wrong. The value of Rs is always positive (by definition), while value of Xs may be negative (capacitor) or positive (inductor). So taking the absolute value of Rs makes no difference, while a negative Xs will result in a negative value of D.
Also, as D is the reciprocal Q, the formula for D (Rs/|Xs|) should be the reciprocal of the formula for Q (|Xs|/Rs)
Gotta love it when you're designing an lcr meter and this just so happens to come out ❤️
And when you just bought one
Sadly this is probably not helpful for you
as a matter of fact I am! And yup, lovit!
Great stuff Dave. I worked a full career in power generation and now I'm an adjunct prof. I can't stress how important fundamentals like these are for engineering students. Sadly, I'm finding that these foundational concepts are not being stressed as they were when I was a student. I hope that students are watching your videos. Keep up the great work!
Many of the students I went to school with complained about this sort of theoretic treatment (a decade or so ago), but I find having a grasp of it massively improves my ability to find solutions in the applications I'm working on.
Without the fundamentals, you can be totally lost when something doesn't work for some reason, or when you need to design something you can't copy from elsewhere. Maybe most people avoid both situations, but I sure can't!
@@martinmckee5333 Agreed. About 10 years ago, a power plant colleague said to me "they don't teach that stuff anymore, students have access to do much info that they don't need to know those concepts.". My response was "but SOMEBODY needs to know this stuff." He paused, then agreed. Bottom line is, engineering isn't about parroting back someone else's material. Without complete knowledge of fundamentals, an engineer is essentially doomed to failure, and should seriously consider switching careers (perhaps to philosophy, or a related trade).
I'll be honest, I'm a bit crap at maths, but videos like this inspire me to make the effort and try to expand my knowledge. I'll have to watch this and the other videos you mentioned several times before the penny drops, but I'm sure I'll get there.
Years ago, when I was in college, I remember being fascinated that we could calculate the dynamic impedance of a diode using Pythagoras Theorem.
I've been a service engineer for over 30 years, and I've NEVER had a practical use for that knowledge, but I'm glad I learned it because I found it very interesting. 😊
For me at my repair bench. Diode working, correct voltage drop across forward biased PN junction. Diode short circuit. Diode open circuit.......Done.
I ♥️ these tutorials. I always learn new stuff or at least reinforce previous knowledge. Cannot get enough.
You can't get enough huh ?
well you said the magic words
SO THIS........... IS FOR YOU
th-cam.com/video/9gEy2FJ_AiA/w-d-xo.html&ab_channel=KneesTease
A suggestion for a video: how to use an LCR meter and what all those Cp, Cs, Lp etc mean.
Damn it Dave, why couldnt you have been my college electronics teacher (for everything) back in my younger times ! Good stuff …thanks….
You timed this one for the overseas markets Dave! Midnight now I'll watch it in the morning mate!
oh, you have no idea how this video came out in a perfect timing!!! Thanks Dave!
You put the fun into phasor diagrams mate!
Pew Pew
I finally bought a DER EE LCR meter a couple days ago, after years of procrastinating on getting a proper one, so the timing of this video is greatly appreciated.
Sir
I salute to your valuable knowledge. thanks for sharing
God Bless You
Nice to see you, your SMPS videos taught me a lot
The measurement doesn't have to be in phase with the source signal, it's only important that the two measurements be 90 degrees apart in phase at exactly the source frequency. This is what the fast Fourier transform does and outputs two vectors 90 degrees apart. Although the phase of the two vectors is random with respect to the source phase, the calculations are exactly the same because it is the ratio of the real and imaginary amplitudes and the relative phase between them that is important.
This simplifies the hardware because there is no need to synchronize with the source as long as the frequency is precise. The A/D sampling has to be frequency precise with regard to the source and then an FFT can use the sampled data to extract the vectors and then calculate component values.
A primitive LCR meter can be made using an Arduino to generate a square wave source with the A/D triggered at four times the square wave frequency to give the proper phasing with half the samples the sine value and the other half the cosine. This is the hardware equivalent of doing an FFT. The first sample is sine +, the second cosine +, the third sine - and the fourth cosine -. The - samples are multiplied by -1 and added to the + samples and averaged to get the amplitude of the vector. The cosine value is the real part of the vector and the sine is the imaginary part.
For higher precision the source voltage should also be measured using the same technique. If this is done, the source voltage value is not important as long as it is stable. The LCR measurement depends only on the ratio of the DUT impedance to the reference resistor impedance and if the same A/D reference is used for all measurements a fairly accurate measurement can be made.
A PC sound card can also be used as the basis of an LCR meter because it can easily source and measure and only requires a simple op-amp input buffering and guarding stage.
Thanks for explaining q and how my old lcr meter works! I'm not sure that all stuck, but the overview really helps me a lot! 👍
Excellent. This was needed for persons whom don't understand impedance.
Perfect Sir.
thanks for explaining in detail
Dave, your a Freak of Nature my mate! ha ha ha.
I LOVE how you believe that for all of us to be able to use a LCR Meter competently , we need to understand 'How a LCR Meter fundamentally works'.
Just simply..... GENIOUS, my Aussie matey.
Side note- A thumbnail to the right just showed a video from 13 years ago, Rigol DS1052E Oscilloscope review Crazy dont you think?
13 years ago...... WOW
The algorithm works in mysterious ways.
@@EEVblog he he he, we love yeh Bruce😉😁
Merci, one of your best videos I think.
Thanks Dave! Now you are our teacher!
Great video Dave, very good presentation. I took a lot of information from it. Thank you.
Thank you, Dave, Great useful video for all the time!
Very good presentation. Thanks Dave for doing this stuff for many years.
Thanks Dave. I Really Enjoy All Your Videos. Seems Like Your The Only One Who Knows How to still Make the Greatest You t ube Videos On Anywhere. Thanks. I'm Designing a Cancelation Circuit for noise and All This stuff Your Currently teaching I will Be Using All Of It In My Design. Thanks Much. VERY VERY Helpful
Just bought a Hantek LCR meter. This helps a lot. Thabks ^^
Crazy video. Thanks for this super explanation!
I'll try and design one myself.. that'd be a very interesting proyect. Nice video..
Greetings from Argentina.
Nice work!! This is pretty cool stuff!
now, that's a juicy piece of content
Nice :)
It goes pretty well with the one about measuring inductance with a multimeter set to capacitance measurement.
BTW, back in 2004 my high school was having some serious remodeling and the labs were to be packed up, so lots of old gear had to go; a few electronics geeks (including me) who were on good terms with the physics and chemistry teachers got some cool stuff. Mine included a vintage '80s analog RLC bridge (Meratronik E316 for those interested) that can measure on DC, 50Hz and 1kHz. I rarely used it, but it's there in case I need to measure a choke.
Quite excellent. Thank you.
Nice calculator mate!
got it, very clear explanation
i love how dave has done almost 1500 videos and theres still some subjects left untouched 😄😄
electronics like most subjects is kinda a cluster*uck, but its so goddamn fun
thats for sure 😊
with Electronics, the truth is 1500 is a small number
you could do a lifetime of videos and still have stuff to talk about
it just keeps going and going, which is why we love it
YOU NOW UNDERSTAND WHY OUR PARENTS BACK IN THE 70S HAD NO PROBLEM WHEN WE STARTING PLAYING WITHOUT 150 IN 1 DICK SMITH ELECTRONICS KITS
it would shut us up for a lifetime or at least until we put it down to have some dinner
This is quality electronic content!
Awesome over my head stuff :)
I felt like 35 years ago in the school ;-) Thank you!
I still reference your 2010 video about an LCR meter you built for marine exploration. This is a healthy update.
Yeah, I think it was very similar, but seemed like an update was in order when doing the next video on in-circuit measurement.
9:48 Slaying⚡️watch with your favorite bud.
Excellent LCR intro.
You did it again! Gold! Thank you dave!. You should open a channel named "what an EE will forget after 10 years" or X years 😉 i the field. Keep these great videos!
I think I need to try and build one of these :)
This was a great video . Do you have a video explaining what all the functions on a lcr meter mean and their function.I just bought the Der ee , De - 5000 .
Thanks Dave! :D
I wish you had gone into into the series and parallel model a bit more as that's actually important understand when doing measurements with an LCR meter. I see people bungling it up all the time. What's the difference between Cp and Cs? Why switching between these give you vastly different values? Some LCR meter don't let you switch between these at certain values, what gives? And so on. Lots to talk about imho. Again, some people I work with have very little experience with LCR meters and like once I year I stumble over someone having measured and documented the wrong one and it being undetected for months. So, you'd do the industry a favor clearing this up.
Yes, could spend another 10 minutes on that. If I wrote a script that would have been in there.
I agree. Pls Dave 🙂
It looks like a good subject of the next video
Back in the olden days when I was in an electronics class at a community college, we were all given a 5H choke, large iron core inductor to measure. We all got some silly number I don't remember but it was very small, like 100uH. Nobody cared, even the teacher, as he didn't know why. I followed through (for weeks) and found our test current was so low, it barely moved the domains and put the BH curve where it almost followed the X axis line. If we had tested with a higher current, the line would have separated from the X axis and we would have got a higher inductance answer. Nobody cared. Sad!
Terimakasih atas penjelasannya dan sub titlenya.god job
Damn... i was expecting how it works but with diagrams and how they are basicly made... Anyways i loved the video!! Thank you dave!!
Wow that quality...
LCR meters are indeed comfortable... but I still like my recently restored LCR bridge; 1kHz frequency, and it allows D/Q read out.
Dave, it doesn't seem like you're really a RF guy but your phase measurement explanation is a really good "intro to Smith charts" ... minus the chart itself. :)
So it's not black magic, thx for explaining how LCR meters work!
Thanks for this, really!
It left me thinking thou. What happens when you force the meter into c or l or r mode? My first idea during the video was it’s just changing what displays where. But your last sentence left me thinking there’s more than that. Is it?
It measures the magic smoke.
Dave, at the end, i could not read the reminder text because there are videos suggestions on front of it
hi nice sharing
Nice show of calculators at the bottom!
Nice.
Dave should design a cheap diy lcr meter. There aren't really any good ones.
nice
Dave, in case you have not realized this yet, any moron on YT can do an onboxing or teardown video, but very few people can provide an education platform for students, technicians, and engineers. Please focus on such "real education" content rather than the fluff. Thanks!!!
I disagree...
Dave's teardowns and unboxing videos provide insight on how the device works/what are the main components of it
@@gustavrsh YES, but Dave is even more valuable on videos like these!!!
I do NOT disagree that his unboxing/comments/analysis/attempt to repair it videos are not equally as impressive or valuable, but the state of the education system is so bad, that it has to be fixed by Dave doing his best to transfer his real-world knowledge to students, hobbyists, and young engineers. And I have nothing against old engineer, we are also having a blast watching these videos.
@@nameredacted1242 Online learning isn't really helping that equation. I once had a job interview where the person asked me how I obtained my degree/edumacation: online or in-person.
@@bitsurfer0101 I think that you are oversimplifying it. "Online education" has the stigma, rightfully so, of taking people's money, giving them a degree, and teaching them nothing, and not testing you well enough. Dave isn't taking your money, no degree is awarded, and it is up to you to determine if you are "educated enough". Dave is SUPPLEMENTING the sh!tificate of sh!tification that you get out of a "formal education system", the on-the-job training, and self-lead studies...
I used to be an adjunct prof until COVID, so I see plenty of issues with the very expensive and not practical formal university education. I was not liked by either students or management because I taught really hard, on a great deal of topics, tested the crap out of students, and gave out plenty of low grades. As an engineer, I tried to raise my future coworkers, but that was interfering with kids' and parents' plans to get a guaranteed piece of paper with a good grade on it, for the (high) amount of money that they paid for it.
And before all of that, I ran on an Associate's for more than a decade, until I start hinting to my management at an avionics company that I would like to become an engineer. They said that for liability reasons they won't allow that, and I need the BSEE. So they paid for it, I spent four years of my life upgrading from an ASEE to BSEE, then they promoted me. You might slip by in a small company and with lots and lots of experience as a tech become an engineer, but in a litigious society and with the management sold the pill that formal education matters, that's how it goes.
One day when I will have my own company, I will give the basic entrance quiz on basic circuit analysis to a tech or an engineer, just to weed out the completely improper applicants, but the bulk of my interview would be: SHOW, NOT TALK, me some projects you worked on in your spare time, at previous jobs, during education, etc. Everyone can BS they way thru a verbal interview, but you can't fake a project (unless it was a team of other people who actually did the work, and you just got the credit, that happens too).
I didn't mean to put Dave into the rest of the bad teachers. He does a great job of educating on things that they don't necessarily teach in class and sometimes on the job-depending on the person's willingness to teach.
EEVBlog. Adding "gray" to your "matter".
Another question: While measuring the quality factor, shouldn't the Xs be measured at the coil's resonant frequency rather than measuring at any random frequency?
Hi Dave, did you ever do a review/teardown on any of the Peak Atlas LCR meters? I've got one that wont start due to an error, here's hoping, Cheers
Nope.
Hi dave i'm considering buying the samsung TA845 usb c charger but in the teardown by charger lab i saw that they are still using Capxon capacitors. Have they gotten any better or should i pass on it?
Why when I pop in 100 nF caps (ceramic I think), does the capacitance slowly drift down (ESR drifts down and Q drifts up)? My Keithley DMM6500 does the same thing with them.
Wonderful video! One thing that confuses me is the graph of the impedance in the bottom center of your board. Impedance is Z = R + jX. So shouldn't Xs be on the imaginary/vertical axis, Rs be on the real/horizontal axis, and Zs be placed where you have Xs marked? For example, if your impedance was Zs = Rs + jXs = 2 + j3, the absolute value (marked with the | | ) of Xs is 3. But the way you have it drawn with Xs being where Zs should be, the absolutely value of Xs would be ~3.6
Hi Dave, thank you for another very informative video. There is something in your notation that seems odd, though. From the equivalent circuit and the complex plane graph, you seem to imply that Xs is a complex number. However, this does not seem to work because Xs is calculated in your formula using Vq, Vp, Iq, and Ip which are all real numbers. I believe, what you were trying to say is that Xdut = Rs + jXs, with Xdut complex and Rs and Xs real numbers. If this is true, it makes sense to say that Xs can be either positive or negative. If this is correct, the reactive part of the equivalent circuit should be jXs instead of Xs, and the red arrow in the complex plane should be Rdut instead of Xs. Xs should be the projection of Rdut on the imaginary axis. Does this make sense?
I think you are correct, but I would think instead of "Rdut" you should be saying "Zdut". Zdut = Rs +jXs. Because saying "Rdut" implies it is a pure resistance.
If the load is purely inductive (so Xout = jwL), and w and L are such that wL = 1. Then we have Xout = j1. Then we know that the current lags the voltage in an inductor by 90 degrees. So if the voltage placed on the inductor is also 1, then Vp = 0 and Vq = 1. The current would be Ip = -1 (since the current lags the voltage in an indcutor) and Iq = 0.
Then if we use your equation for Rs, we correctly get Rs = 0. But if we use your equation for Xs, we should get +1, but the answer I get is -1. Xs = [ (1)x(-1) + (0)x(0) ] / [ (-1)^2 + (0)^2 ] = -1 / 1 = -1.
If I do the same thing but with a capacitor instead of an inductor, I would except to get Xs = -1, but instead I get Xs = +1.
Am I missing something or is there a sign error somewhere?
So if we are measuring a R and C for a device then we have to connect the device in the parallel mode right?
I've always seen it as V-sub-D & I-sub-D (D for direct) and V-sub-Q and I-sub-Q (Q for quadrature)
I have a confusion over here: wt = 0 degree and wt = 90 degree are two different instances. How are we getting Vp and Vq by extracting the values at two different instances... The vector V in your diagram is the voltage phasor at a particular instant. How would you get info about V's component in Vo axis at a particular instant if we measured at two different times?
amazing sir. Hoe to measure the R L in series and C in parallel that is the one end of C at R and another is grounded. It will form the RLC lumped model. How to measure RLC of the RLC lumped model of interconnect using LCR meter? Please guide sir
Yup, good explanation. Now take that theory and implement using nothing but analogue components and a moving coil meter.
Or just use a DSP.👍🏻🇬🇧
Why do these meter never auto discharge components before testing? it always up to the user to discharge caps?
And what about that strategically placed calculator ?
I think you are saying that the meter measures the phase angle difference between the voltage peak and the current peak - is that right?
That is what I thought so I am not sure what Dave is saying. Scalar measurements of the voltage and current, and then a measurement of the phase between them which is much easier than what he suggests, is enough. Making a sampled measurement at 90 degrees is possible but why?
Modern instruments may do something completely different using a pair of FFTs. Read the Analog Devices application notes on the subject.
@@Alamagosa An FFT effectively samples at 90 degrees when it multiplies by sine and cosine. The only difference is that the relative phase between the source and the sine and cosine samples is random. This is not relevant to the measurement because all vectors are rotated the same and its only the phase difference between them that is important.
Am I correct that all these formulas are trigonometric? I recognized that impedance is A^2+B^2=C^2 rewritten then seemed to recognize a few more.
It's possible to use trigonometry to get the values, but using complex arithmetic is much, much simpler.
Can you use an LCR meter to directly determine the impedance of an audio transformer both on the secondary side (4, 8, 16 ohm) and in the primary side (for matching to a tube for example). When you acquire an unlabeled transformer it would be very helpful to know this. I assume this would be done at 1Khz but I'm not 100% sure. I measure the outer wires on my secondary to be 3.5mH, @1Khz this translates to 22 ohm. From the center tap on the secondary it measures .9 mH which translates to 5.7 ohms. Thanks
Now if I measure my speaker (Using my very cheap LCR meter) the "8 ohm speaker" measures 1.9mH. At 1 Khz the impedance would equal 2*3.14159*1000 Hz*0.0019mH = 11.9 ohm ... nowhere near 8 ohms. At 400 Hz it would be 4.8 ohms and at 5 Khz would be 59.7 ohm. Thoughts?
How does the frequency used in the meter affect the reading and determination (L, C or R)?
Capaciatne and inductance values are both determined by frequency. You can tell because the formula for them I showed will contain omega (W) which is 2 x Pi x Frequency
What's with the calculators?
but what happens when the meter measures something that is more than 90 degrees out of phase?
If I'm thinking correctly, it's just opposite of resistance so conductance? Measured in Siemens or mhos?
That simply cannot happen. It would imply a negative resistance, which would result in an increase in voltage the longer the circuit.
If it could happen we could have perpetual motion.
@@fcolor0430- conductance is the inverse of resistance, not the opposite.
very interesting, i love these math videos 😎 ok ok, now for the hobby world there are some basic arduino LCR learning examples, would the ESP32 be good for this? with a touchscreen some simple XY plotting would be possible for Inductance capacitance to play with on a rainy day 🙄 keysight U1733C is about $515? 🤩 thanks a lot
The Keysight is not cheap. It's nice, but bettre value to be had elsewhere.
@@EEVblog thank you
The face of Dave is scary than the concept themselves....
can you do a video using oscilloscope and function generator as a LCR meter, thanks...
I meant this: th-cam.com/video/115erzCCxgE/w-d-xo.html
@@barrybogart5436 thanks
this is the easy way
AD5933 ?
👍
Can anyone explain this, i was walking under an electrical pylon during a rainy and misty night, holding an umbrella. I could see electrical bolts running from the umbrella into my hand. The pylon was leaking into the mist ? i dont quite understand. I feel lucky to be alive.
$20 meter gives youa good idea tho ,great video
"American rubbish" - them's fighting words! BTW - Excellent video!
Hello Dave, I came over from a mention in a Thunderfoot Video. I would like to know if you heard about this supposed new company that says they have new proprietary 3D cell architecture increases energy density and maintains high cycle life. I think you and Thunderfoot have done videos on companies that try to bring new batteries to market but end up not being viable or just a scam. I was wondering what you think about this company and is it worth doing a video on. The company name Enovix based in Fremont, California. Do you think based on the information they provide on their website that they will revolutionize the battery industry as it stands today?
Never heard of them. But the rule of thumb is that almost every new battery company is impractical bullshit until proven otherwise. Almost all of them go nowhere.
@@EEVblog Thank-you very much for getting back to me I really appreciate it. That is exactly what I thought and I think it might be a theranos of battery tech in Silicon Valley. They are listed on NYSE and show picture of prototypes. Where the scam part comes in is that some representatives of the company said they have been going to Korea for weeks to close a deal with a Korean OE. To me that is outrageous, why would Samsung, LG, Hyundia etc need to buy unproven technology when they spend billions on their own battery technology.
👍👍
Anybody:. I assume there is a single chip available for purchase that does ALL of this, including the phase angle correction, the imaginary numbers, etc?
If I can buy a kit for ten bucks that can be built into a functional LCR tester, I have to assume it is built around a single dedicated purpose chip?
It is a great video. But can you explain the equations of Rs and Xs. Rs = (Vp x Ip + Vq x Iq)/ (Ip2+Iq2) and Xs = (Vq x Ip + Vp x Iq) / (Ip2 + Iq2)
I think Xs=(Vq x Ip-Vp x Iq）
Oi Dave..... any middle finger vids comin up like the dymo scam.... LMFAO :)~
Here I am sitting at home watching a math tutorial on a white board ... And quite enjoying it 🤔. What's wrong with us?
I think you explained this in another video 12 years ago
So why the hell are LCR meters so friggin expensive?
Hey Dave
THAT'S SNEAKY
If Linus had a Father.
You lost me at "hello".