Do I misunderstand ESR measurement? Frequency dependence of ESR - Page 1
Forum section: electronics / beginners

author: golden_labels
author_rank: Super Contributor
timestamp: October 02, 2025, 08:19:33 am
content: I feel like I deeply misunderstood some basic concept. 😳Context:Repair → Is this capacitor dead??In the linked thread OP uses 100 Hz to measure ESR of a capacitor from a rectifier circuit.Multiple people advised using a higher frequency. The suggestions appear to assume:There are some “more preferred” test frequencies, which arenotthe frequency relevant to its operation within circuit.That there is some “true,” constant value of ESR, an intrinsic, physical property of a capacitor.This goes against what I always thought ESR is.In my mind it’s a function of frequency. A parameter in an abstract approximation of a capacitor. A way to combine multiple independent physical phenomena, each occupying its place across the frequencies spectrum, into a single curve in the model. Consequently we evaluate it at the frequency, which is relevant to circuit’s operation.May anybody comment on that? Studying resources I found on the web, including manufacturers’ datasheets and technical notes,(1)only strengthens my perception.I assume that it’s not about meter’s own calibration limits, as onlyJoe Smith’s postpoints in that direction. But if this is the issue, then the thing is clarified to me.(1)As an example, this chart from TDK’s “Film Capacitors” note (fig. 14, p. 16):Vishay’s equivalent (p. 2):

author: gf
author_rank: Super Contributor
timestamp: October 02, 2025, 12:05:26 pm
content: Quote from: golden_labels on October 02, 2025, 08:19:33 amIt is a matter of the equivalent circuit you are using to model the real-world component. Ideally, the component values of a good equivalent circuit should be frequency-invariant within the frequency region of interest. However, in practice it is a compromise between simplicity of the model and modeling accuracy over the frequency range of interest. An R-C series model [ Z(f) = 1/(j*2*PI*f*C) + ESR ] is very simple, but it may not be able to describe the actual Z(f) accurately enough. The other extreme is e.g. the attached equivalent circuit (source:https://www.researchgate.net/publication/235909332_Equivalent_Circuit_Models_for_Discrete_Passive_Components). While it may be able to model Z(f) much more accurately over a wide frequency range, it's likely too complex for most practical use cases.

author: golden_labels
author_rank: Super Contributor
timestamp: October 02, 2025, 03:54:06 pm
content: To clarify the question: it’s about one of the standard models used by most LCR meters. An ideal capacitance (C) in series with an ideal resistance (ESR).If this model is considered, in my mind ESR is a function of frequency. But this is not the picture I get from the other thread.

author: wraper
author_rank: Unknown
timestamp: October 02, 2025, 04:11:23 pm
content: QuoteFirst of all, if ESR is like <0.01% of total Z, how meter is even supposed to measure it? Secondly, it's unlikely that datasheet spec for 50n capacitor will be given at 100Hz test frequency.

author: TimFox
author_rank: Super Contributor
timestamp: October 02, 2025, 04:25:12 pm
content: The series model in the drawing above represents what the ESR meter, or an LCR meter in series mode, reports at a given frequency. A similar drawing with a parallel resistor can be calculated from exactly the same measurement. If theQof the physical component is high, say >100, the capacitance (series or parallel) at a given frequency in the two models will be almost equal, but the two resistance values are very different, roughly by a factor ofQ2.Consider two different capacitors (both limiting cases):In one case, the parasitic resistance of the plates and leads is negligible, and the loss is dominated by the inherent properties of the dielectric. If the dielectric’sQis essentially constant over a reasonable range of frequency, then the ESR =XC/Qwill be proportional to 1/f.In the other case, something like an electrolytic capacitor with the electrolyte as part of the series circuit, theQof the internal capacitor dielectric (like aluminum oxide) could be high, and the ESR is dominated by the parasitic series resistance. In that limiting case, ESR is constant butQis proportional to 1/f.

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2025, 04:44:31 pm
content: Quote from: wraper on October 02, 2025, 04:11:23 pmYeah that's an angle of 89.9982 degrees for the impedance for a 300Ω ESR and 50nF Cap at 100Hz.ConsideringhowLCR meters make this measurement, which isn't direct but evaluated from the voltage across the DUT and the voltage from a transimpedance amp for the DUT current, the result uncertainty is large, and a measurement at a higher frequency is necessary. One of the often overlooked parameters of LCR meters is the actual measured DUT voltage and current, some meters these are displayed which can help with assessing the DUT measurement at hand.Models of physical components can vary from simple to extremely complex, with the latter usually associated with a broader frequency coverage. One should remember that all electrical components are frequency dependent to some extent, and should consider such for measurements and actual use.... even a wire or PCB trace has limits for a simple "connection" as shown on a schematic!!Best

author: gamalot
author_rank: Super Contributor
timestamp: October 02, 2025, 05:01:40 pm
content: Quote from: golden_labels on October 02, 2025, 03:54:06 pmIf the ESR in this series model is an ideal resistor, then why would it be a function of frequency?

author: TimFox
author_rank: Super Contributor
timestamp: October 02, 2025, 05:22:27 pm
content: Quote from: gamalot on October 02, 2025, 05:01:40 pmThe ESR isnota physical resistor, it is a parameter of the physical capacitor and is usually a function of frequency. At a fixed frequency, the capacitance and ESR values of the capacitor can be considered “ideal”, since they are part of a model: that’s not the same thing as “physical”.

author: bdunham7
author_rank: Super Contributor
timestamp: October 02, 2025, 05:31:35 pm
content: Quote from: golden_labels on October 02, 2025, 03:54:06 pmIf I understand you correctly, themodel itselfrepresents ESR as a single, fixed value in series with an ideal capacitor but in real life the measured value will change due to non-ideality. Thus if you want to represent the capacitor with that simplistic model, the value for R will be different at different frequences. That seems to me to be a correct way of thinking about it.If you use a more complex model and start adding in additional parastics like ESL, then the resistive component in your model may be closer to a constant value over a range of frequencies. If you make a model with series resistance, leakage resistance, series inductance, etc using fixed values you could get a result that pretty closely matches measurements over a fairly wide frequency range. You'll get better results with a model if you use a high-quality film capacitor with low dielectric absorption and voltage coefficient issues rather than an electrolytic or MLCC.

author: gamalot
author_rank: Super Contributor
timestamp: October 02, 2025, 05:31:43 pm
content: Quote from: TimFox on October 02, 2025, 05:22:27 pmI know ESR isn't a physical resistor, I'm just saying that OP's two statements contradict each other.

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2025, 05:34:44 pm
content: Quote from: gamalot on October 02, 2025, 05:01:40 pmThink of ESR as the complex aggregateEquivalent Series Resistanceof all the energy loss elements within the capacitor. This include, leads and/or terminations, dielectric loss, plate or metal film conductance, and skin effects, all of which are somewhat frequency dependent. Lumped all together in a single ideal model resistor called ESR.Best

author: gamalot
author_rank: Super Contributor
timestamp: October 02, 2025, 05:37:33 pm
content: Quote from: mawyatt on October 02, 2025, 05:34:44 pmWhat I'm saying is that since ESR is a function of frequency, you can't call it an ideal resistor.

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2025, 05:51:09 pm
content: Quote from: gamalot on October 02, 2025, 05:37:33 pmIdealin our context simply means a lossy element. If the lossy resistor in the model weren't ideal, then additional terms/components/descriptions need to be applied to the ideal lossy resistor. Aresistor modelcould include frequency depended terms/components as well, and a completely separatemodeljust for the lossy resistor.In IC design when one creates a schematic in Cadence for example, the capacitor is a highly complex sub-circuit model which is comprised of multiple additional components, some ideal and some not with their own sub-circuits, various resistor types also have highly complex models often with layout dependent terms as do capacitors.It all just depends on how deep you want to dive wrt to modeling the capacitor.Best

author: bdunham7
author_rank: Super Contributor
timestamp: October 02, 2025, 05:59:37 pm
content: Quote from: gamalot on October 02, 2025, 05:37:33 pmImagine a potentiometer driven by a motor that is controlled by an MCU that senses frequency. That's a ridiculous model, but if you use the simplistic model consisting of an ideal resistor in series with an ideal capacitor, that's one way you could model the resistor. The point is that using that oversimplified model requires you to assign various values for R that depend on frequency.

author: gamalot
author_rank: Super Contributor
timestamp: October 02, 2025, 06:04:22 pm
content: Quote from: mawyatt on October 02, 2025, 05:51:09 pmI feel like "resistor" works just fine here. Save "ideal resistor" for the kind that doesn’t change with frequency, temperature, or humidity.

author: TimFox
author_rank: Super Contributor
timestamp: October 02, 2025, 06:06:39 pm
content: The series R-C connection is amodel, and the two elements of the model areideal, as in most models of complicated entities.In this case, since the data were measured at a single frequency, theRandCvalues represent the "real" and "imaginary" components (in the mathematical sense) of the measured complex impedance at that frequency.When you change the frequency on the LCR meter, you should expect different values, especially ofRbut also ofCdue to the influence of the parasitic series inductance of the part.Further non-ideal behavior, not measured by these meters, is non-linear behavior of the real and imaginary components, which may be important at high voltage levels (especially with non-linear ceramic dielectrics such as Z5U).

author: gamalot
author_rank: Super Contributor
timestamp: October 02, 2025, 06:15:41 pm
content: Quote from: TimFox on October 02, 2025, 06:06:39 pmAlright, back to the point. I don’t recall anyone saying ESR is constant in that other post. If LCR meter seeing 300 ohms ESR on a 50nF cap at 100Hz, that’s probably not because of frequency, it’s just the LCR meter not being accurate enough.

author: TimFox
author_rank: Super Contributor
timestamp: October 02, 2025, 07:19:31 pm
content: Quote from: gamalot on October 02, 2025, 06:15:41 pmQuantitatively: the reactance of 50 nF at 100 Hz is 32 k\$\Omega\$. Taking the measurement literally, that isQ= 100, if ESR = 300\$\Omega\$.Depending on the capacitor dielectric, that is believable for a good capacitor with a class-2 dielectric.

author: David Hess
author_rank: Super Contributor
timestamp: October 02, 2025, 10:05:04 pm
content: Quote from: TimFox on October 02, 2025, 06:06:39 pmThe dielectric constant also changes with frequency to some extent, and more so at low frequencies. The dielectric constant of materials like FR4 can change considerably with frequency at low frequencies which results in printed circuit board "hook" in high impedance circuits.

author: TimFox
author_rank: Super Contributor
timestamp: October 02, 2025, 10:19:48 pm
content: Quote from: David Hess on October 02, 2025, 10:05:04 pmYes. I remember an article inElectronic Designback in the 1980s where Tektronix showed the result of FR4 dielectric dispersion and absorption on pulsed waveforms.For non-electrolytic capacitors (film and ceramic), theQof an individual part changes much more slowly than those effects, so the ESR is expected to go roughly as 1/ffor a given part, and roughly as 1/Cfor similar capacitors.Several posters here bring up a measured or suspected ESR value for a given capacitor and don't compare it with the capacitance, frequency, and therefore reactance.

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 04:51:29 am
content: Quote from: TimFox on October 02, 2025, 07:19:31 pmYeah, I get what you're saying and it checks out. But if I had to take a guess, I'd say that big cap is probably a film one.

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 05:14:44 am
content: Great, I found the datasheet. It's an oil-impregnated capacitor with a plastic dielectric.If we using a 0.5% power factor, its ESR at 100 Hz is roughly 160 ohms. Another post reports a measured value of around 330 ohms, not great, but not terrible either.---I always thought that even the crappiest film caps wouldn’t go over 0.1% D value at 100 Hz. I was wrong...

author: tggzzz
author_rank: Super Contributor
timestamp: October 03, 2025, 06:57:28 am
content: ESR is amodelof what happens in a physical component. So isevery other parameterof a capacitor that you find in a capacitor's datasheet. If you don't believe that, start by considering the C-vs-V variation in MLCCs, and then move on to dielectric absorptionAll models are wrong, but some are useful. So work out what matters in your circuit, and measure that. For digital circuits, that often means the response to a step voltage change superimposed on a DC voltage.

author: Zero999
author_rank: Super Contributor
timestamp: October 03, 2025, 09:58:04 am
content: Quote from: golden_labels on October 02, 2025, 08:19:33 amYes, you are correct that ESR is frequency dependant, but:How do you know that 100Hz is the "correct" frequency? The original poster just said it's a smoothing capacitor on a 15kV rectifier circuit. No mention was made of the frequency. It might be on the secondary of a transformer, driven by an oscillator, running at a much higher frequency. Even if the rectifier is run at 50Hz, the current pulses into the capacitor have much higher frequency components than 100Hz and the load might draw short pulses, again with much higher frequency components.How the heck is one supposed to accurately measure the ESR of a 50nF capacitor at 100Hz? As mentioned above, the capacitive element of the impedance will dominate the ESR, by several orders of magnitude, at this frequency.The only way to measure the ESR of such a low value capacitor, is to use a much higher test frequency. Yes, as your graphs show, the ESR is frequency dependant, but it doesn't increase significantly until about 10kHz or so. If a test frequency of 10kHz is used, then it should give a fairly accurate result, perhaps a little higher than at 100Hz, but much more accurate than trying to measure it at 100Hz and since, one is testing to see if it's good, then erring in the side of caution is sensible, so a slightly higher reading is desirable.

author: chilternview
author_rank: Frequent Contributor
timestamp: October 03, 2025, 10:19:11 am
content: Just out of interest I measured a 1nF capacitor - the sort that is sold on eBay by the chinese as a 'standard capacitor'.On a Keysight E4980A measuring Cs-Rs over 20Hz-1MHz, the Rs was pretty constant from 1kHz up at 20-30 ohms. Below 1KHz, it increased to ~1k at 100Hz. Also the curve was very erratic at low frequency, not sure if that is due to measurement error due to the high impedance at low frequencies, or noise, or both.

author: MrAl
author_rank: Super Contributor
timestamp: October 03, 2025, 10:40:11 am
content: Quote from: golden_labels on October 02, 2025, 08:19:33 amHello there,Although it the truest sense ESR may be frequency dependent, but you should also consider it being application dependent: depending on what you are using the capacitor for. For example, in switching power supplies it is better to check the ESR with a pulse because that how it will be used in the circuit, and it is rather easy to check this way.To understand the effects in sensitive circuits we'd also have to consider ESL. The model then looks like:Z=1/(jw*ESC)+jw*ESL+ESRwhereESC is the equivalent series capacitance,ESL is the equivalent series inductance,ESR is the notorious equivalent series resistance.The magnitude is then:|Z|=sqrt(ESR^2+(w*ESL-1/(w*ESC))^2)This would show the the capacitance ESC dominates at low frequencies, then for midrange frequencies ESR kicks in, then for higher frequencies ESL dominates.Note even this is a simplified model and it does include ESL which shows that the behavior is not all the simple. It's a 2nd order system in itself.Now getting back to the switching power supply circuits, the ESR can be checked by using a pulse. For example, a resistor in series with the cap, measuring the voltage across the 'capacitor'. The capacitance part does not charge up right away because of all the resistance in series with it, but because the ESR drops voltage immediately, we see the voltage across the physical capacitor jump up suddenly. That is due to the ESR and depending on the cap we may see a little ESL activity.With an electrolytic, it's mostly the ESR and we see the voltage jump up according to Ohm's Law. If we divide the spike in voltage by the current, we get a value that represents the ESR. That's the ESR that would start to heat up the cap and reduce efficiency.That's just one application. If you are working with some sort of filter, it could get a lot more complicated depending on how accurate your filter has to be.This just touches on some of the complications we see with capacitors. It's a complex device, but the level of complexity we have to think about depends on the application as well as the physical capacitor itself.

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 11:25:02 am
content: Quote from: chilternview on October 03, 2025, 10:19:11 amHave you performed the open and close corrections?

author: joeqsmith
author_rank: Super Contributor
timestamp: October 03, 2025, 12:23:37 pm
content: Shown is the 5nF PCI I previously showed in other thread. Very poor setup but we can see this part resonates at roughly 1MHz. At resonance, all we have left is R.

author: MrAl
author_rank: Super Contributor
timestamp: October 03, 2025, 01:15:55 pm
content: Hello again,I had forgotten to mention that I would almost never use an ESR meter of some kind unless it was highly advanced. An ESR meter that uses only one frequency, by now, should be understood to be just not good enough. There is one case where I might use on, and that is if it was used on a regular basis for testing capacitors that are known to usually have specific characteristics and those would be tested on a more or less regular basis, and the meter was known to be able to spot bad ones.Also, this reminds me a lot about testing inductors. Inductors are even harder to test in the most general cases. That's because they usually need a certain level of current in order to test them properly. A low current inductor may be able to be tested with a general-purpose inductance checker, but a high current inductor needs higher current to test properly. That's because of the difference in BH curves, which is a characteristic of the core material and type. One core may only need 10ma to test, while another may need 10 amps to test. That's how different they can be.For switching power supplies, the best test is to test it in the application itself. Does it show the right inductance; does it show the right ESR; does it saturate. Those are very important test points which you usually need a scope for. You would need a very well-made inductance 'meter' to test for that.

author: David Hess
author_rank: Super Contributor
timestamp: October 03, 2025, 01:34:34 pm
content: Quote from: Zero999 on October 03, 2025, 09:58:04 amYou combine two things, time and an integrated measurement. We are very good at measuring time, so combine that with an integrated measurement to accurately measure the phase offset from 90 degrees. Integration lowers the noise level.I suspect nobody bothers to do this because the answer is not interesting to designers; measuring the ESR/D at a higher frequency is good enough.

author: golden_labels
author_rank: Super Contributor
timestamp: October 03, 2025, 01:46:21 pm
content: I needed time to digest all the replies.Given the number of them, forgive me not replying to each of them separately.First and foremost: if it’s about the limitation of the LCR meter and/or the ability to measure relatively tiny ESR, as e.g. Joe Smith hinted in the linked post, to me this is clear. There is no conflict with what I know.The R-C diagram I included is only to visually indicate, which of the standard models I mean. To avoid confusion. The square box is not a physical resistor or a fixed resistance, it’s the ESR in that particular model, with all it entails. It’s drawn as a resitor, because it represents the resistive part of the measurement. As opposed to the reactive part, which is drawn as either a capacitor or an inductor, depending on which model is assumed. This includes the true, ohmic, frequency-independent resistance of the conductors. But it’s only one of the factors ESR represents. That’s why there is “equivalent” there and not only “series resistance.”⁂My concern is only about the part, where people suggest measuring the ESR at a different frequency. Yes, it will be within LCR meter’s capabilities, it will be much more accurate, the reactive component will not swamp it. But it will also be ESR at a different frequency.For example: we may get a very accurate 254 Ω @ 1 kHz. Great. Where this conflicts with my understanding, is that this 254 Ω will not hold at other frequencies, including 100 Hz we’re interested in.I hope I’m clear now.⁂joeqsmith: now I almost feel guilty for making you put that much effort into this thread.Zero999: strictly speaking I made a mistake of assuming it’s rectified 50 Hz. But the same would apply to anybody commenting there.

author: wraper
author_rank: Unknown
timestamp: October 03, 2025, 02:11:13 pm
content: Quote from: golden_labels on October 03, 2025, 01:46:21 pmWhat you measure at "not a different frequency" is a trash reading that's likely 100-1000 times off the actual value to begin with. It's like measuring thickness of 1mm thick steel plate covered with 10 cm of solidified mud with calipers and insisting that you certainly must measure it with mud present because it's used this way. Not to say ESR of a 50nF capacitor at 100Hz is irrelevant as the circuit won't "see" it at this frequency in the same way as LCR meter does not.

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2025, 03:06:19 pm
content: Quote from: David Hess on October 03, 2025, 01:34:34 pmSee post #5."Yeah that's an angle of 89.9982 degrees for the impedance for a 300Ω ESR and 50nF Cap at 100Hz.Considering how LCR meters make this measurement, which isn't direct but evaluated from the voltage across the DUT and the voltage from a transimpedance amp for the DUT current, the result uncertainty is large, and a measurement at a higher frequency is necessary. One of the often overlooked parameters of LCR meters is the actual measured DUT voltage and current, some meters these are displayed which can help with assessing the DUT measurement at hand."Best

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2025, 03:19:53 pm
content: Here's a couple examples we made awhile back showing Capacitor Impedance and ESR vs. Frequency. Not a 50nF cap under discussion, but a 5uF PP 250V and 470uF 6.3V Polymer type which shows ESR behavior over frequency.Best

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 03:45:52 pm
content: Quote from: mawyatt on October 03, 2025, 03:19:53 pmIIRC, you have more than one precision LCR meters. Why not try measuring a film capacitor around 50nF? I believe the results will be much more promising than most people would expect.

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 04:05:06 pm
content: I grabbed a few 2.2nF MPPS film capacitors and tested their ESR at 100Hz. I tried three setups: two in parallel, single, and two in series. The results came out to 0.07kΩ, 0.13kΩ, and 0.26kΩ respectively.The capacitor model is SMR5222J100J01, proudly co-produced by three leading brands: Yageo, Kemet, and Evox.

author: TimFox
author_rank: Super Contributor
timestamp: October 03, 2025, 04:20:54 pm
content: 2.2 nF @ 100 Hz:XC= 720 k\$\Omega\$, soQ= 5600 for ESR = 130\$\Omega\$, consistent with the manufacturer's specs.A very good capacitor: requires a good LCR meter to resolve the loss (not a cheap ESR meter or DMM).

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 04:30:27 pm
content: Quote from: TimFox on October 03, 2025, 04:20:54 pmYeah, the cheap ones probably won’t cut it. I tried using my LCR tweezers, and measured around 6kΩ ESR at 100Hz.

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2025, 04:35:39 pm
content: Quote from: gamalot on October 03, 2025, 03:45:52 pmYes we have two Bench LCR Meters, a Hioki IM3536 and Tonghui TH2830, unfortunately we don't have any quality 50nF film caps (actually don't haveany50nF film caps!!)!!If you want to send us one/some we'll be happy to measure them for youWe did quickly measure a few GP film type caps we have using the TH2830 @ 100Hz2.2nF 260Ω2.2nF 270Ω10nF 46Ω10nF 62Ω100nF 24Ω100nF 24Ω1uF 0.39ΩBest

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 04:40:44 pm
content: Quote from: mawyatt on October 03, 2025, 04:35:39 pmLet’s be honest, who doesn’t have a drawer full of 100nF caps? Just put two in series and you're good to go.

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2025, 04:59:44 pm
content: See our edit above, you should be able to figure out from thatBest

author: TimFox
author_rank: Super Contributor
timestamp: October 03, 2025, 05:14:17 pm
content: Quote from: mawyatt on October 03, 2025, 04:59:44 pmCalculatingQfrom your 100 Hz measurements:2.2 nF: approx. 2800 for both10 nF: 3460 or 2587100 nF: 663 for both1 uF: 4081From that, I infer that the films (except 100 nF) are polypropylene. Are the 100 nF polysulfone or polycarbonate?

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2025, 05:25:29 pm
content: Quote from: TimFox on October 03, 2025, 05:14:17 pmCaps are either PP or Mylar. The 100nF are likely Mylar, others PP. Don't think we have any other type film caps except PS, but these are smaller values. We do have some Mica and larger PP types tho.Here's the 100nF type.Best

author: TimFox
author_rank: Super Contributor
timestamp: October 03, 2025, 05:49:04 pm
content: My educated guess, based only your measured data, are that at 100 Hz, the film capacitors' loss is dominated by the dielectric loss, since the capacitive reactance value is very high compared with ohmic resistance of the internal metal.Presumably, for the larger capacitance values, at higher frequencies (still below self-resonance) theQ, with lower reactance, will fall somewhat due to the actual resistive loss.

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 05:54:32 pm
content: Just measured a polystyrene film cap, the Q was over 10,000 at 100 Hz! Might be some error, but still super impressive.https://au.rs-online.com/web/p/film-capacitors/4263110

author: TimFox
author_rank: Super Contributor
timestamp: October 03, 2025, 05:58:15 pm
content: Quote from: gamalot on October 03, 2025, 05:54:32 pmYes, polystyreneQis very high: what capacitance did you use, and what is theQat 1000 and 10,000 Hz?My DE-5000 can distinguish reliably betweenQ= 100 andQ> 1000, but I wouldn't trust the value atQ= 10,000.I use it to verify polypropylene (high) vs. polyester (mediocre).

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 06:12:28 pm
content: Quote from: TimFox on October 03, 2025, 05:58:15 pmOops, turns out that Q of 10,000 was an error. I ran another test, here’s what I got this time:100Hz Q=58311kHz Q=5368 (5382)10kHz Q=4642100kHz Q=8160Number in brackets is from the Agilent 4288A. The cap I tested is the 10 nF model in the link.

author: TimFox
author_rank: Super Contributor
timestamp: October 03, 2025, 06:14:58 pm
content: Your results look reasonable: the 100 kHz value may be affected by the parasitic inductance.What was the capacitance?

author: gamalot
author_rank: Super Contributor
timestamp: October 03, 2025, 06:16:50 pm
content: Quote from: TimFox on October 03, 2025, 06:14:58 pmThe 10nF model in the link.

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2025, 07:07:15 pm
content: Just quick check a few larger PP types we have:4.8uF 5550 @ 100Hz3.9uF 6300 @ 100Hz1uF 3500 @ 100, 5700 @ 1k, 2600 @ 10k, 496 @ 100kHzThese Qs seem reasonable for larger PP types.A couple old Soviet Hermetic Mica types:10nF 4340 @ 100, 15000 @ 1k, 8400 @ 10k, 921 @ 100kHz4.4nF 3200 @ 100, 12500 @ 1k, 7000 @ 10k, 1540 @ 100kHzThese old Soviet Micas are impressive, would not have expected them to be this good considering their construction!BTW for high Q measurements the Hioki IM3536 is the better instrument than the TH2830 which we utilized.Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 04, 2025, 05:21:11 pm
content: Measured a 1n, 10n & 1uF with BK and cheap VNA using a home made test fixture. Parts are physically much smaller that what was originally asked about in the other thread.1nF BK@10kHz 1.035nF, 6 ohm ESR, 3000 Q, VNA 1.08nF, resonance 33MHz, 0.366 ohm ESR @ res10nF BK@10kHz 9.858, 2.46, 650 Q, VNA 9.85nF, resonance 11.4MHz, 0.193 ohm ESR @ resI did not recal for the 1uF part...1uF BK@10kHz 1.024uF, 0.144, 109 Q, VNA 953nF, resonance 1.4MHz, 0.174 ohm ESR @ rescap is of course open at DC, but shown impedance zoomed in.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 04, 2025, 11:37:34 pm
content: Retesting the 1uF after performing a calibration over a range of 10k to 5MHz, we can see it resonates at 1.28MHz with an ESR of 24mOhms.

author: gamalot
author_rank: Super Contributor
timestamp: October 05, 2025, 03:04:41 am
content: The 1 µF capacitor you have is most likely a metallized polyester type. I tested a few 1 µF film capacitors I had on hand, and the Kemet MMK shows data very similar to yours, while other metallized polypropylene capacitors perform significantly better.The following data reflects results at 1 kHz and 10 kHz respectively.Kemet MMK 1.005/0.996µF Q=247/118Kemet R75 1.017/1.017µF Q=5147/2655Panasonic ECWFD 1.002/1.002µF Q=4352/926Würth FTBP 0.973/0.973µF Q=4976/1226Unknow Chinese Brand CBB22 1.005/1.004µF Q=2708/1303

author: joeqsmith
author_rank: Super Contributor
timestamp: October 05, 2025, 02:19:59 pm
content: I don't have many film capacitors on-hand. I have a Polycarbonate 1uF that has a Q of 130 and ESR of 0.120 @ 10kHz, when measured with the BK.

author: Zero999
author_rank: Super Contributor
timestamp: October 05, 2025, 05:32:00 pm
content: What sort of wave form do the capacitor testers use? Is it sine or square? I wonder if it's the latter, in which case it should be easier to measure the ESR, even with low test frequencies, by looking at the voltage or current, when the waveform changes from one voltage to another.

author: TimFox
author_rank: Super Contributor
timestamp: October 05, 2025, 05:44:55 pm
content: ESR is a parameter defined for a sinusoidal waveform, and it varies with frequency.The reactance, obviously, is much different at the third and fifth harmonics.The result measured with a square wave will differ from the true ESR, but might be useful as a diagnostic for larger capacitance caps.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 05, 2025, 05:47:30 pm
content: Quote from: golden_labels on October 02, 2025, 08:19:33 amESR stands for Equivalent Series Resistance. So it is a resistor (and therefore frequency independent) that is used as a model as a first order approximation of a real physical capacitor. You can make models for a capacitor that more closely follow the frequency dependent imperfections of a real capacitor, but you you'd have to model it for a specific type (and possibly size) of capacitor.So there is a difference between the simply modeled "ESR", and real capacitor behavior, and when simulating (where you can use "Ideal" passives and then add parasitics to more closely follow real life parts) is always a compromise between accuracy, simulation speed and time spend to build / verify the simulation results.

author: TimFox
author_rank: Super Contributor
timestamp: October 05, 2025, 05:55:37 pm
content: In fact, the ESR in the model for a physical capacitor can be measured readily at different frequencies and is a function of frequency.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 06, 2025, 02:56:47 pm
content: Quote from: gamalot on October 05, 2025, 03:04:41 amI checked and indeed, it is PE. Looking around at work, we have some old PS parts. These should have a low dissipation factor.

author: gamalot
author_rank: Super Contributor
timestamp: October 06, 2025, 03:28:17 pm
content: Quote from: joeqsmith on October 06, 2025, 02:56:47 pmPE as polyethylene? It's really uncommon.

author: TimFox
author_rank: Super Contributor
timestamp: October 06, 2025, 03:45:34 pm
content: Quote from: gamalot on October 06, 2025, 03:28:17 pmPE ispolyester, i.e. polyethylene terephtalate or PET, commonly known as MylarTM. It is really, really common. As a capacitor dielectric, it has mediocre loss but allows smaller physical size than, for example, polypropylene, which has a lower dielectric constant that requires more area.

author: gamalot
author_rank: Super Contributor
timestamp: October 06, 2025, 06:22:46 pm
content: Quote from: TimFox on October 06, 2025, 03:45:34 pmThese full English names are too hard for me to remember. I often mix them up. I can only remember some of the abbreviations.For example, I know what a PET capacitor is, but I didn’t realize that PE means the same thing …

author: Bernd_2
author_rank: Contributor
timestamp: October 06, 2025, 06:43:31 pm
content: Hello,As far as I know, PE is the usual abbreviation for polyethylene.See also Wikipediahttps://en.wikipedia.org/wiki/Polyethylene.Best RegardsBernd

author: Zero999
author_rank: Super Contributor
timestamp: October 06, 2025, 06:46:39 pm
content: Quote from: golden_labels on October 03, 2025, 01:46:21 pmThat wasn't my point.Take a bridge rectifier, with a capacitor and constant current load. Look at the FFT of the current through the capacitor: there's still plenty of energy in the 1kHz range.

author: TimFox
author_rank: Super Contributor
timestamp: October 06, 2025, 07:26:17 pm
content: Quote from: Bernd_2 on October 06, 2025, 06:43:31 pm“Polyester” is a very generic term for polymers.No one makes polyethylene capacitors.PET capacitors are extremely common, and are often (carelessly) referred to as “polyester” by engineers.“Mylar” is a registered trademark of DuPont, like “Nylon”, or Kleenex for Kimberley-Clark.When first introduced as a substitute for paper-dielectric capacitors, ca. 1953, PET capacitors were often called Mylar, but you won’t find that term now on Mouser’s search engine, but other vendors do not recognize the trademark.For actual polyethylene, the longer-chain polymerization leads to higher density, hence the grades LDPE and HDPE.If you ask a vendor for “PE” or polyester capacitors, he will certainly sell you PET.Abbreviation meanings differ from application and profession. In medicine, “PE” means “pulmonary embolism”.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 06, 2025, 08:31:55 pm
content: Quote from: gamalot on October 06, 2025, 03:28:17 pmPE as in polyester. Very common.https://www.mscpl.com/general_technical_information.htmlArticle on the end of Polystyrene capacitors.https://www.electrocube.com/pages/white-paper-what-happened-to-polystyrene-capacitors-data-sheet

author: joeqsmith
author_rank: Super Contributor
timestamp: October 06, 2025, 08:55:24 pm
content: Back when polystyrene was a thinghttps://www.edn.com/wp-content/uploads/2016/11/1982-10-13_EDN_Pease-capacitor-soakage.pdf

author: TimFox
author_rank: Super Contributor
timestamp: October 06, 2025, 09:05:43 pm
content: In the Pease article, he shows a model for a "Mylar" capacitor, with mediocre soakage.The main problem with polystyrene is its low service temperature, which makes it difficult to use with modern through-hole PCB fabrication.(I don't believe PS was ever made in surface-mount: surface-mount film capacitors use plastics with high temperature rating.)

author: joeqsmith
author_rank: Super Contributor
timestamp: October 06, 2025, 09:31:58 pm
content: Quote from: TimFox on October 06, 2025, 09:05:43 pmHe talks about polystyrene's limited temperature in that article. "... although polystyrene can’t be used at temperatures greater than 80°C" We used it for sample and hold in automotive (-40 - 85C). Back then, we were using all TH, wave solder.Somewhere around, I have one of the very first surface mount boards we ever did. Hybrid of TH and SMT. Hand placed and soldered.

author: TimFox
author_rank: Super Contributor
timestamp: October 06, 2025, 09:34:54 pm
content: Similarly, in a multiplexer and ADC board that I designed at the beginning of my career, we used through-hole components and wave soldering, but specified hand soldering for the four polystyrene capacitors used in sample-hold circuits.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 06, 2025, 11:30:46 pm
content: I think the main problem with using polystyrene is we have not made those parts in decades.100pF caps measured with BK @ 10kHz, CD-ceramic disc PS-polystyreneType, val, ESR, QMica, 100.5, 200, 1300CD, 97.5, 1640, 100PS, 102.8, 77, 2200Air 98.9, Q hunts, Dissipation factor 0500pF (PS 480pF) measured with BK @ 10kHzMica, 520.1, 23, 1300CD, 481.2, 540, 64,2PS, 481.6, 10.5, 3500Air 486, Q hunts, Dissipation factor 0***Uncalibrated, looking at S11 impedance of the 100pF PS vs air capacitors

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 07:36:31 am
content: I'm not a native English speaker, so I really dug deep to figure this out. I did tons of searching, used translation tools, and even asked a few different AIs for help.In the end I found that PET and PE are totally different materials (just like I used to think), PET is widely used in making film capacitors, while PE is more for things like packaging and insulation.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 07, 2025, 11:06:24 am
content: Quote from: golden_labels on October 02, 2025, 03:54:06 pmI do not understand the argumentation in your mind.The rectangular thing representing the ESR is a resistor, and frequency independent.The capacitor on the right represents the capacitor itself.In the end it also depends on the definition of ESR you use.If you consider it to be an "idealized parasitic" as a part of modelling a real life capacitor, then it is a simple resistor, and thus frequency independent.If you use a practical approach and define it as "a bunch of the non-idealities of the capacitor thrown together" then it may very well be a frequency dependent part.Capacitors have a lot of non-ideal behavior. ESR, leakage, inductance, dielectric absorption, voltage dependent capacity change (especially with ceramics) just to name a few.Also, if you are measuring ESR on a "real life" capacitor, you are not only measuring the "idealized resistor", but you are unavoidably measuring a mixture of other non-ideal behavior too. And that's one reason the measurement method and frequency are mentioned.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 01:36:26 pm
content: Quote from: gamalot on October 07, 2025, 07:36:31 amI am not sure there is much to figure out. I called out the dielectric, and provided you with a link of the nomenclature for a reference:https://www.mscpl.com/general_technical_information.htmlThe old Illinois Capacitor books from the 70's and 80's were a few inches thick and loaded with details. They may provided you with some of the history. I have attached a paper from 1984. You will notice they only show the same basic four that were listed in the link I had provided. Historically speaking, marketing, sales & EEs could only pack so much into two letters but you can see why we used PE,PP,PS & PC to identify them. Over time, this confusion may be why we now have an IEC standard where dielectrics begin with "K" and one letter for the material. For example, KP is Polypropylene. Of course, you have things like Polyphenylene sulfide which is KI rather than KS.....

author: mtwieg
author_rank: Frequent Contributor
timestamp: October 07, 2025, 02:12:19 pm
content: Overall it's unclear what question this thread is trying to address... seems to have turned into a dumping ground for everyone's personal capacitor anecdotes. Many of these anecdotes are interesting and worth discussion, but probably not in the same thread...IMO, ESR does not have a "true" definition. If you put a gun to my head and forced me to choose, it would probably "the real component of the measured complex impedance, with some AC measurement frequency/amplitude/bias". Of course ESR can also be measured in the time domain (as is standard for supercapacitors). The proper method of characterization depends on your application.

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 02:12:53 pm
content: Quote from: joeqsmith on October 07, 2025, 01:36:26 pmI totally understand that you're used to calling it PE. Just to clarify though, since English isn't my first language, I'm not familiar with that usage or the historical reasons behind it.From what I’ve seen so far, on major distributor websites and in manufacturer datasheets, polyethylene terephthalate (polyester) usually referred to as PET. The only place I’ve come across the PE logo is on everyday recyclable polyethylene plastic bags.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 02:41:03 pm
content: Quote from: gamalot on October 07, 2025, 02:12:53 pmI did provide you with a link, so if you have not seen it called out this way, that's on you. I'm used to referring to them as PE as that is what we were using early on.

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2025, 03:00:03 pm
content: Quote from: Doctorandus_P on October 07, 2025, 11:06:24 amThe model drawn as a capacitor and resistor in series: if you assume the resistance to be independent of frequency, that model is not accurate for a physical part. Some LCR meters can fit the parameters of a more complicated model to data measured over a range of frequencies. A simple LCR meter can measure accurately the ESR at different frequencies, and each value is usable near the frequency where it was measured.Using the simple model with frequency-independent ESR value in a Spice calculation involving a wide frequency range can be inaccurate.

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2025, 03:07:35 pm
content: Quote from: joeqsmith on October 07, 2025, 02:41:03 pmLogical issue: polyethylene, polyester, physical education, and pulmonary embolism are English terms in different applications, each abbreviated as “PE”. Therefore, one needs context to translate the abbreviation when seen in a given place. For capacitors, “PET” is a polyester, and defines the material better than “PE”, but when buying the part, one will see PE as well. There is a standard for labeling plastics for recycling that distinguishes PE for polyethylene from PET for MylarTM, but that standard is not used in commerce for capacitors.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 03:28:30 pm
content: The following was taken from IS:7305-19843. DESCRIPTION AND CODE3.1 The description of the type of the capacitor may be in the form of afour character code, consisting of alphabets F F as follows :Group 1 - FC - Fixed capacitorsGroup 2 - AL-- Aluminium electrolyticCG - Ceramic, general purposeCM - Polycarbonate, metallizedCT - Ceramic, temperature compensatingFT - Foil, tantalumMA - MicaPC - -PolycerbonatePE - PolyesterPP - PolypropylenePS - PolystyerenePM - Polyester, metallizedST - Solid tantaluhttps://law.resource.org/pub/in/bis/S04/is.7305.1984.pdf

author: tggzzz
author_rank: Super Contributor
timestamp: October 07, 2025, 03:34:52 pm
content: Quote from: mtwieg on October 07, 2025, 02:12:19 pmYup. There are significant differences in the operating conditions of audio circuits and SMPSsWork out what is important inyourcircuit, and find a way to measure the capacitor in a way that reflects how it will perform in your circuit.

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 03:45:40 pm
content: Quote from: joeqsmith on October 07, 2025, 03:28:30 pmYeah ... but why Indian standards?

author: golden_labels
author_rank: Super Contributor
timestamp: October 07, 2025, 03:51:37 pm
content: Quote from: Zero999 on October 06, 2025, 06:46:39 pmIf this is why people suggested measuring at 1 kHz instead of 100 Hz, then at least now I can see what was the motivation.I don’t feel convinced about the great importance of that choice or it being preferred, but this is besides point here. I only wanted to know about the reasoning behind that advice and to verify my own perception. Both questions are now answered.Thanks to all.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 04:01:51 pm
content: Quote from: gamalot on October 07, 2025, 03:45:40 pmWhy not? You have something against the fine people of India?I believe this nomenclature was common at that time, at least at the USA based companies I worked for.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 04:27:19 pm
content: It appears China was using it as well.PP：Polypropylene Film （CBB21，CBB13，CBB81，CBB20，CBB18，X2-MKP，X1-MKP）PE： Polyester Film （CL71，CL21X，CL21，CL11，CL12，CL20，X2-MKT，X1-MKT,CL21-B）To me it's a pretty minor deal. I still use this older nomenclature but I doubt anyone here would care if you used Mylar or PET.

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2025, 04:33:02 pm
content: Note the additional letter “M” for film caps that distinguishes metallized film (now, the most common) from film-foil capacitors.There is another polyester type, chemical abbreviation PEN, used in capacitors, but I have not encountered it myself.

author: David Hess
author_rank: Super Contributor
timestamp: October 07, 2025, 04:46:29 pm
content: I was giving some thought to this and I think I see the conflict. The following will be obvious to many here, but maybe I can describe it in a more understandable way.ESR is defined in terms of the real part of the loss related to dissipation, which includes all loss mechanisms:D = ESR / Xc, where D is Dissipation, or 1/Q, and Xc is Capacitive Reactance, or 1/(2*Pi*F*C)or rearranged, ESR = D * Xc and Xc = 1/(2*Pi*F*C), so ESR = D/(2*Pi*F*C)For film or ceramic capacitors, D is usually in the range of 0.1 to 0.01, and even lower for better parts, so ESR is a very small fraction of the capacitive reactance, as expected.With the dissipation (loss) being roughly constant over frequency, ESR has to be the same fraction of the capacitive reactance as the capacitive reactance changes with frequency. For this to be the case, ESR, like capacitive reactance, has to be inversely proportional to capacitance and frequency. At low frequencies the capacitive reactance increases, so the ESR also increases for the dissipation to remain constant.This is the ESR as reported by an LCR meter or network analyzer. If you know the dissipation or quality factor, D or Q, and the capacitive reactance, then you can calculate this ESR, which is what would be done if you were using an impedance bridge for the measurement which only returns D or Q. Our modern LCR meters do the calculation for us.The conflict is that in the time domain, we see ESR as a step in voltage across the capacitor for a step in current, and this is not the same ESR as measured by an LCR meter at low frequencies. Instead, it's value roughly converges with the ESR reported by an LCR meter at high frequencies. Capacitor datasheets typically use a 100 kHz test frequency for this ESR, but as the capacitance decreases, a higher test frequency is needed to get this "practical" value of ESR that we need to estimate ripple voltage for a given ripple current.

author: golden_labels
author_rank: Super Contributor
timestamp: October 07, 2025, 04:56:42 pm
content: Quote from: gamalot on October 07, 2025, 03:45:40 pmIf you’re worried about this being applicable to other countries: national industry standards are often copies of international standards, or at least based on them or reflecting practices aligned with international standards. Bureau of Indian Standards itself is a member of both IEC and ISO.In this case there is no need to guess: IS 7305 is based on IEC 384, which is explicitly mentioned.

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2025, 05:00:20 pm
content: As I posted earlier, there are two extreme cases between which practical capacitors fall:1. A low-loss capacitance in series with a substantial parasitic resistance. Electrolytic capacitors can have an aluminum oxide dielectric layer in series with an electrolyte. Recent improvements in these capacitors have concentrated on different series mechanisms. In that extreme case, ESR would be independent of frequency.2. A construction with negligible parasitic resistance (plates and leads) in series with a capacitance whose loss given byQ= 1/Dis independent of frequency. As noted above, that gives an ESR inversely proportional to frequency, following the drop in reactance as frequency increases.This complicates the calculation of step response in the time domain. It’s easy for case 1, but that approximation is not exact. It’s possible but complicated for case 2, but the Spice model for capacitors (for example) can’t use that model directly.

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 05:00:31 pm
content: Quote from: joeqsmith on October 07, 2025, 04:27:19 pmChinese this time?I've got nothing against Indians or Chinese, no bias at all. Right now, China produces a ton of high quality electronic components, and maybe India will too in the future.As for that Chinese capacitor datasheet you're looking at, the "PE" is just part of the model number. Their naming system only allows two characters to indicate the dielectric type, so obviously they can't use "PET."And honestly, in China, nobody uses "PE" to mean polyester film capacitors. Trust me, I'm Chinese.And just to wrap up, like I said earlier, I've done a ton of homework on this. That’s no joke. I'm dropping a picture here to prove it.

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2025, 05:05:01 pm
content: Yes, PET is careful usage, which is a good thing.However, if you see a capacitor (as opposed to a water bottle) labeled “PE”, you should assume PET for the chemical composition.If you should find a polyethylene capacitor, you might worry about its temperature rating.

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 05:09:10 pm
content: Quote from: TimFox on October 07, 2025, 05:05:01 pmSo here’s how it all started: I'd never seen a "PE" film capacitor before, so I decided to be careful and double check using translation tools and search engines. What I found was that it's actually a pretty rare type of capacitor ...

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 05:19:06 pm
content: Quote from: gamalot on October 07, 2025, 05:00:31 pmAgain, PE was an old nomenclature, like Mylar. While searching the internet is fast and can cover a lot of ground, it falls short when it comes to a historical archive. What I suspect you have provided is mostly from the last two decades. That standard from India dates back a little further.Google AI shows:AI OverviewQuoteITW 223J04PE590 Type PE Polyester Film Capacitor. Capacitance 0.022 uF. Voltage rating 400 VDC. Tolerance 5%. Radial terminals.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 05:21:55 pm
content: Quote

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2025, 05:27:03 pm
content: Quote from: gamalot on October 07, 2025, 05:00:31 pmYour examples of careful use of "PET" are to be applauded.Historically, the first such capacitors used DuPont trademarked "Mylar", meaning "MylarTMpolyester", which was shortened to "polyester" when other manufacturers' material was used.Not everyone is so careful: here's a simple result from Mouser's search engine on capacitors:https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?dielectric=PolyesterMy point is that in normal commerce, one must be aware of the term "polyester capacitor" or "PE capacitor" and its meaning in context.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 05:29:04 pm
content: The following snip is from a 1977 Tektronix manual.https://w140.com/tekwiki/images/1/10/070-1797-00.pdf

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 05:39:39 pm
content: Quote from: joeqsmith on October 07, 2025, 05:29:04 pmOf course I believe what you said, and I totally believe that people used to refer to polyester capacitors as "PE."I’m just saying that since I didn’t know any of this to begin with, I turned to translation tools, search engines, and AIs, and ended up confused.If I said anything that gave you the wrong impression, it’s just because my English isn’t that good.

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 05:44:11 pm
content: Quote from: TimFox on October 07, 2025, 05:27:03 pmSorry I think I got myself confused again. I clicked the link you sent, but I wasn't quite sure what insight you were trying to point me toward.

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2025, 06:14:49 pm
content: Quote from: gamalot on October 07, 2025, 05:44:11 pmThat link searches for "polyester capacitors" in the Mouser inventory. Other choices for the search include "PET". I'm just pointing out what terms are used for selling capacitors, even though strictly speaking there are many polyesters. Polyethylene and polypropylene are "polyolefin" plastics. That general term is usually found in electronics for heat-shrink tubing.

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 07:00:18 pm
content: Quote from: TimFox on October 07, 2025, 06:14:49 pmAh, I get what you mean now, thanks a lot! I've always known that PET, polyester, polyethylene terephthalate, and Mylar all refer to the same type of capacitor. I just didn't know that some people used to call it PE too.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 07:36:14 pm
content: Quotehttps://yuan-corp.goldsupplier.com/

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 07:41:23 pm
content: Snip taken from 1976 Wireless World magazine:https://www.worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1976-07.pdf

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 07:46:35 pm
content: ELECTRONICS, VOL. 18, NO. 1, JUNE 2014Measuring Capacitor Parameters Using Vector Network AnalyzersDeniss Stepins, Gundars Asmanis, and Aivis Asmanis

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 07:58:53 pm
content: Application Note:ESR Losses In Ceramic Capacitorsby Richard Fiore, Director of RF Applications EngineeringAmerican Technical Ceramics2007

author: joeqsmith
author_rank: Super Contributor
timestamp: October 07, 2025, 08:03:08 pm
content: The Methods and Problems of Capacitor ESR MeasurementKnowles CapacitorsNorwich, U.K.2016,Link to article:https://www.microwavejournal.com/articles/27237-the-methods-and-problems-of-capacitor-esr-measurementAPPLICATION NOTE 6014HOW TO MEASURE CAPACITY VERSUS BIASVOLTAGE ON MLCCSBy: Fons Janssen, Principal Member of the Technical Staff, and Field Application Engineer, Maxim IntegratedLink to article:https://www.analog.com/en/resources/technical-articles/how-to-measure-capacity-versus-bias-voltage-on-mlccs.html

author: joeqsmith
author_rank: Super Contributor
timestamp: October 08, 2025, 05:59:23 pm
content: QuoteThis article series was published in audioXpress, from November 2001 to January 2002.https://audioxpress.com/article/Choosing-and-Using-Electronic-Parts-A-Survival-Guide-Part-1

author: joeqsmith
author_rank: Super Contributor
timestamp: October 08, 2025, 06:03:16 pm
content: The attached was taken from the Luxman M-02 service manual.https://www.manualslib.com/manual/3552451/Luxman-M-02.html#manual

author: G0HZU
author_rank: Super Contributor
timestamp: October 08, 2025, 10:15:05 pm
content: At low frequencies (<300kHz) and with reasonably large capacitors, (>100nF?) it is possible to measure ESR quite well using a clean signal source and a known series sense resistor in series with the DUT capacitor with the far end of the DUT cap grounded. Then measure the AC voltages around the sense resistor using a decent (true RMS reading) DVM.Something like a Keithley 2000/2015 or an Agilent 34401A bench DVM would be ideal here. Then the ESR can be calculated based on the AC voltages measured around the sense resistor. By using a measured sense resistor (resistance accurately measured by the bench meter) and a clean signal source (low harmonics) the measurement accuracy should be quite good in most cases. This method can't be used with small capacitors as the DVM capacitance will become significant for one thing. Also, it's best to limit the maximum frequency to about 100 kHz but 300kHz is possible with a decent bench DVM. It's best to do the calculations with Excel and it should be possible to semi automate the process by also using Excel to log the AC voltages via GPIB. Even then it will be clunky and slow but it should be a good way to cross check readings made by something like a DE-5000 ESR meter.

author: TimFox
author_rank: Super Contributor
timestamp: October 08, 2025, 10:30:25 pm
content: It would be easier to connect the external sense resistor to ground, with the capacitor under test between the signal source and the capacitor.This will work at frequencies where the capacitive reactance 1/wCis much less than the ESR, so that the impedance in series with the sense resistor is essentially equal to ESR.Real LCR meters, such as the DE-5000 and others, use phase-sensitive measurements to measure the voltage components in phase and in phase quadrature with the current through the device.

author: G0HZU
author_rank: Super Contributor
timestamp: October 08, 2025, 11:11:14 pm
content: I’m not sure what you mean. The aim is to work out both the capacitance and the ESR and it doesn’t matter (within reason) if the reactance is larger than the ESR or vice-versa. It should still be able to work out the ESR from the AC voltmeter readings.The choice of sense resistor value (and its accuracy) is important although I usually use 100R for measuring caps.This method can’t tell the difference between inductive and capacitive reactance but usually this isn’t an issue and there are workarounds for this with tests at different frequencies.

author: TimFox
author_rank: Super Contributor
timestamp: October 08, 2025, 11:26:30 pm
content: The magnitude of the voltage across the sense resistor (in either position, but easier to measure if grounded) gives you the magnitude of the current through the device.The magnitude of the voltage across the capacitor (again, in either position, but easier to measure if grounded, so you can't do both) gives you the voltage across the device, and therefore the magnitude of the impedance of the device.With a high-Qcapacitor (at that frequency), the reactance is much higher than the ESR, so the magnitude of the impedance is very close to the value of the reactance.The magnitude of the total voltage across the two units in series is computed similarly.That's why LCR meters require a phase-sensitive measurement.

author: David Hess
author_rank: Super Contributor
timestamp: October 08, 2025, 11:37:24 pm
content: Quote from: TimFox on October 08, 2025, 10:30:25 pmThat is how dedicated ESR meters work. The idea is that they use a frequency high enough that the capacitive reactance is insignificant compared to the "practical" ESR.I never had a dedicated ESR meter, so what I used to do is measure the dissipation of the capacitor with my impedance bridge which operated at 1000 Hz, and from that it was readily apparent if an electrolytic capacitor was worn out. I think D is a better measurement since it is roughly constant over frequency unlike true ESR which is frequency dependent.

author: G0HZU
author_rank: Super Contributor
timestamp: October 08, 2025, 11:44:49 pm
content: Maybe apply this to an example cap like a 1uF WIMA cap? Test it at 10kHz and 100kHz for capacitance and ESR. The ESR would typically be quite low, especially at 100kHz. It should be less than 0.1 ohm?I’d expect the sense resistor and AC voltmeter method to work quite well. Probably well enough to compare against a low cost handheld LCR+ESR meter.

author: TimFox
author_rank: Super Contributor
timestamp: October 08, 2025, 11:49:09 pm
content: 1 uF at 100 kHz has a reactance of 1.6 ohms, and 16 ohms at 10 kHz.Adding (real) 0.1 ohms to the (imaginary) 1.6 or 10 ohms reactance will not change the magnitude of the impedance much, nor affect the current through the device.A good film capacitor will haveQ> 100, so the expected ESR can easily be < 0.1 ohms, depending on dielectric.It's easier to design an ESR meter for electrolytic capacitors with much lower reactance and higher ESR.

author: G0HZU
author_rank: Super Contributor
timestamp: October 08, 2025, 11:56:54 pm
content: Quote from: TimFox on October 08, 2025, 11:49:09 pmNone of that matters in this case. The sense resistor method will still be able to predict that the ESR is <0.1 ohms at 100 kHz. It can’t tell if it is a capacitor or an inductor but usually that doesn’t matter so the reactance can be assumed to be capacitive in this case.A decent AC voltmeter with 5 digits and good accuracy and low drift is important as this helps to minimise uncertainty.

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2025, 02:23:00 am
content: The simple model of a capacitor impedance is Z(w) = {R + jwL - j/(w*C)}.Without phase information (i.e. scaler measurements) for Sinus excitation, then to evaluate R in Z(w) one must selectwsuch that the difference in |wL - 1/(wC)| << R, otherwise you can't separate the Real and Imaginary parts of Z(w). At lowwthen 1/(wC) dominates and at highwthenwL dominates. Of course this becomes easy atwwhere |wL-1/(wC)| ~ 0 (series resonance) or simplyw~ 1/sqrt(L*C).Here's an example of a cheap 1000uF Electrolytic where Z and Real part converge at ~>10kHz and a cheap Polypropylene 10uF with higher "Q" where they converge only ~ 300kHz. Note that acquiring a good measurement for the PP cap withscalartechniques would be difficult anywhere but ~ 300kHz as the high "Q" pulls Z much higher anywhere outside of series resonance making separating Real and Imaginary Z(w) error prone.Please note the 10uF PNG plot designation of1uFis incorrect, should be 10uF (if anyone requires a 1uF film type, we can perform this at request) .Best

author: TimFox
author_rank: Super Contributor
timestamp: October 09, 2025, 03:36:55 am
content: Quote from: G0HZU on October 08, 2025, 11:56:54 pmNo.If you measure rms AC voltages, you will get the magnitude of the impedance of the device under test.Here's an example with even numbers:Assume the magnitude ofXis 10 ohms (inductive or capacitive) and the ESR is 0.1 ohms for aQof 100 at the test frequency.The magnitude of the impedance is then [X2+R2]1/2= [100 + 0.01]1/2= [100.01]1/2= 10.0005.That last 0.0005 in the impedance is equivalent to a tolerance of the capacitance value of 50 ppm.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 06:46:53 am
content: Quote from: TimFox on October 09, 2025, 03:36:55 amIf it helps, I’m measuring the AC voltages around the sense resistor. I measure the input voltage, the voltage across the series sense resistor and the voltage across the DUT capacitor and from this I can calculate both the reactance and the ESR.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 09:03:55 am
content: Quote from: mawyatt on October 09, 2025, 02:23:00 amIt’s still possible to calculate the ESR if you measure the input voltage, the voltage across the sense resistor and the voltage across the DUT capacitor and this can be done with a regular AC voltmeter. From this it’s possible to reverse engineer both the magnitude of the reactance and also the ESR at the test frequency. It isn’t necessary to have meter that measures phase to do this. I use a Keithley 2015THD DVM on the AC voltage range. This meter has 6.5 digits and can measure Vrms to 300kHz.

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2025, 01:15:25 pm
content: Quote from: G0HZU on October 09, 2025, 09:03:55 amAnyscalarvoltage measurement (DVM ACrms) reveals themagnitude[sqrt(Imaginary^2 + Real^2)] of the voltage measurement, wether across a resistor (Real), ideal capacitor/inductor (Imaginary) or complex impedance (both Real and Imaginary like Cap DUT).How do you propose to extract the Real part (R) of a complex impedance ({R -j/(wC)} of Cap DUT) unless the capacitive reactance 1/(wC) is << than R?Please look at the plots we provided above of two capacitors, one electrolytic and the other a PP film. These plots show the actual measured (Hioki IM3536) Impedance Magnitude Z (blue trace) and Real part (red trace). Note how the electrolytic (low Q) Magnitude Z and Real part converge above ~10kHz, here a scalar measurement can resolve the Real part as the Magnitude Z which is [sqrt(Imaginary^2 + Real^2)] and becomes ~Real when the Imaginary is << Real. Under this condition the scalar Z measurement is dominated by the Real part.However, the 10uF PP Film cap is a higher Q and the scalar measurement needs to be conducted around 300KHz since this is the only frequency where the Imaginary is much less than the Real. Also note the Imaginary partincludes the inductive reactanceas well as the capacitive reactance which resonate together as shown in the higher Q PP film Cap and reveal the true Real part as at resonance the Imaginary part is 0, so Z simply becomes the Real part!!Edit: We've added the mentioned plots annotated to illustrate the discussion above, hopes this helps.Best

author: TimFox
author_rank: Super Contributor
timestamp: October 09, 2025, 02:19:49 pm
content: Again, the magnitude (or scalar) measurements can only give the magnitude (complex absolute value) of the device’s impedance. Phase-sensitive (or vector) measurements are required to separate the real (resistance) and imaginary (reactance) components of that impedance.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 03:35:16 pm
content: Often when I try and share knowledge and experience on the web, an ‘expert’ stubbornly refuses to accept my input. This time there’s two of them and they are posting up lots of equations and theoryIf you make three scalar voltage measurements you can reverse engineer the ESR of the DUT using just an AC voltmeter even if the ESR is much smaller than the reactance. This technique has been around for many years but it does require a few equations to work out the vectors from three scalar measurements.According to both of you, this can’t be done because of your schoolboy reasoning about the reactance being much bigger than the ESR.

author: tggzzz
author_rank: Super Contributor
timestamp: October 09, 2025, 04:26:34 pm
content: Quote from: G0HZU on October 09, 2025, 03:35:16 pmConsider fighting fire with fire, or equations and numeric examples in this case.

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2025, 04:49:24 pm
content: Quote from: G0HZU on October 09, 2025, 03:35:16 pm

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 04:59:16 pm
content: I'm quite busy at the moment so I can't spend much time on this, but I've dug out my old excel spreadsheet for this stuff. Give me some more time and I'll set up some 'real' tests with real test gear.I've used a simulation (shown below) to get the AC voltages and then put them into the spreadsheet. All I put into the spreadsheet is the 100R sense resistance, the test frequency (10 kHz) and the three AC voltages. It then gives me the reactance and the ESR.In this case the ESR is 0.1R and the reactance is about 16 ohms.It's years since I created this spreadsheet and I moved on to an automated method via GPIB and a little EeePC netbook and a VB6 program. I'll have to extract the equations from the excel spreadsheet but I may have the original IEEE article somewhere.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 05:07:46 pm
content: Same test jig, same test frequency but ESR of the model increased to 0.25R. You can see two of the three voltages are now subtly different and this is why you need a really good voltmeter for this stuff. The source has to be clean and stable too.It calculated 0.2497R for the ESR at 10kHz.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 05:16:13 pm
content: Quote

author: tggzzz
author_rank: Super Contributor
timestamp: October 09, 2025, 05:17:42 pm
content: Quote from: G0HZU on October 09, 2025, 04:59:16 pmYou show the results ofasimulation ofsomethingusing somehiddencalculations.Show the equations used to specify the calculations, defining the terms as appropriate.

author: tggzzz
author_rank: Super Contributor
timestamp: October 09, 2025, 05:19:17 pm
content: Quote from: G0HZU on October 09, 2025, 05:16:13 pmMesdames et Messieurs, faites vos jeux s'il vous plaît.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 05:27:17 pm
content: Quote from: tggzzz on October 09, 2025, 05:17:42 pmI can't find the IEEE paper yet but it should be obvious that you can sometimes reverse engineer angles (vectors) from multiple scalar measurements. This isn't rocket science.I may have to log in to work to get IEEE access or you could just google for "three voltage method impedance" or something like that. This should find numerous papers on this but they might not have accurate equations. Probably lots of diagrams and lots of equations though...Note: If you want to try this yourself using test gear, don't use three different voltmeters to speed up the process. It's best to just use one even though it takes longer to do it. Otherwise the accuracy may suffer.

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2025, 06:55:51 pm
content: Quote from: G0HZU on October 09, 2025, 05:27:17 pmHow are we supposed to utilize the 3 scalar measurements to resolve the real part of the capacitor impedance. We all can make these measurements, we just did on a 1uF film cap utilizing a KS34465A for all 3 measurements and verified the C and Rs at 10KHz by IM3536 LCR measurement, so we know what the correct answer is!!A quick preliminary look at the math by a page of scribbles indicates the result is a quadratic in Rs which "hints" that the results might be highly influenced my measurement inaccuracies!!Please enlighten us with how to apply these 3 scalar measurements, we are eager to learn something newBest

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 07:07:32 pm
content: FFS just googlethree voltage method impedanceFor the theory and equations.if I measured a 1uF WIMA cap at 10 kHz the reactance is going to be about -15 ohms. The ESR is probably going to be less than 0.2R.In your (and TimFox's) interpretation of reality I can't possibly measure this with scalar measurements because the reactance is 80 times greater than the ESR at 10kHz.In my reality, I think the three voltage method will be able to get quite close to the correct ESR of 0.2R at 10 kHz. I know this because I've made these measurements many times.For sure it isn't going to deliver metrology grade accuracy but it will be able to deliver similar results to a hobby grade handheld LCR/ESR meter. Which is why I suggested it as a way to cross check the results from a typical LCR meter to see if they are sensible.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 07:45:43 pm
content: Give me some time this evening and I'll set this up. I'll measure the ESR of a 1uF WIMA cap at 10kHz and then I'll put a precision 1 ohm 1% resistor in series with it and measure it again. The second reading should be ESR + 1 ohm. I know this is going to work well because this was the way I evaluated this process many years ago. So I'll be measuring a ~1 ohm ESR for a cap with about -15 ohm reactance for the second reading.To do this properly requires a fixture with two test sockets. Obviously, I can't use a soldering iron to make any connections or it will cause thermal drift. So I'll need to add another test socket with the 1R resistor at the ground end.It isn't going to compete with $$$ lab instruments but it will at least prove to the 'experts' and doubters here that it is possible to reverse engineer vector based information from a set of three scalar measurements. This technique is decades old but it does require a very good voltmeter and a clean and accurate and stable signal source if you want to measure capacitors like a 1uF WIMA at a few kHz

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2025, 08:13:26 pm
content: Well we just made the measurements based upon the AI description. Curious why you won't post your methods and "hidden" calculations?AI claims solution by constructing a vector diagram and solve by using law of cosines? This doesn't make sense as how do you construct a Vector Diagram with 3 Scalars? Anyway we followed the description and the result for Rs was 0.395Ω at 10kHz with KS34465A, we repeated the 3 measurements and computations with same result.However, our measurements of the same capacitor (1uF film) on our IM3536 (1.00236uF and 28.14mΩ) with a leaded TH26048A fixture at 10kHz. So we repeated the measurement on our TH2830 at 10kHz, at 1.00238uF and 28.51mΩ.Edit: Checked another 1uF Film Type Knscha MPX/MKP, measured 1.02550uF 18.12mΩ with IM3536, using the 3 scalar technique described by AI we get RS = 118mΩ!!Went back and measured with the 3 scalar technique, same result, Rs = 0.395Ω.Not sure what to make of this 3 scalar technique, maybe we messed up the measurements/calculations (per AI)BTW still waiting for your technique details and "hidden" calculationsBest

author: armandine2
author_rank: Frequent Contributor
timestamp: October 09, 2025, 08:27:05 pm
content: ...in my AI search I added loss angle , better suited than esr , to 3 voltmeter method.. and my google search for 3 voltmeter method showed how to measure and calculate power factor (albeit in an inductive load).

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 08:28:00 pm
content: This is getting a bit like Youtube where everything is declared 'fake' by all knowing keyboard warriorsAnyway, it took me less time than expected to set this up and I tested with the raw 1uF cap, then with 0.1R inline and then with 1R inline. I have to say the results came out better than expected but this time I used an old Agilent ESGD sig gen to output an LF signal at 10 kHz as this has very low distortion and is very accurate and stable.The images below are screenshots from my EeePC for all three cases. You can see that the ESR was about 0.16R at 10kHz. With the 0.1R 1% resistor it was 0.27R and with the 1R 1% resistor it was 1.17R.By all means study the voltage readings and try and prove the basic ESR measurement is fake or wrong or whateverSome of the other onscreen cell data was added as useful info but these cells may contain nuts as I only really look at ESR and reactance etc.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 08:37:45 pm
content: You can also see in the top right corner of the EeePC GUI I added a crude uncertainty indicator. There are test conditions where this setup can give huge measurement uncertainty if an unsuitable sense resistance or test frequency is used. So the cells in the top corner show how much the results change with a voltage error for at least one of the voltage readings. I can't remember how I set this bit up but it can be very useful as it easily spots cases where I've used the wrong sense resistor and/or test frequency.

author: gf
author_rank: Super Contributor
timestamp: October 09, 2025, 09:15:03 pm
content: Quote from: mawyatt on October 09, 2025, 08:13:26 pmHere's how Gemini explains and derives the ESR estimation with the 3-voltmeter method:https://g.co/gemini/share/c2a7524730d0I checked it only briefly, but the calculation seems plausible.Even more interesting would be error propagation, i.e. how the relative uncertainty of the estimated ESR depends on volt meter uncertainty, Q of the DUT, and the choice of Rref.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 09:29:48 pm
content: Quote from: armandine2 on October 09, 2025, 08:27:05 pmYes, in recent years, I've moved across to using an Analog Discovery 2 for measuring components so this is the first time I've used the Excel spreadsheet or the EeePC program in quite a while. The AD2 is much faster and it may well be more accurate most of the time. It can use a sense resistor too and it can measure phase so it can compute ESR a different way.Many years ago I used to use a two channel scope to measure ESR by measuring amplitude and phase but this was quite clunky and not as accurate. I use a different tab of that excel sheet when using a scope. I've also used my HP8405A vector voltmeter for this stuff too. But not many people will have an AD2/3 or a vector voltmeter. The AC voltage + sense resistor method can give good results as long as a decent AC voltmeter is used. If the wrong choice of sense resistor is used for a chosen component or an unsuitable test frequency is chosen then it can give crazy results. So some experience is needed.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 09:39:55 pm
content: QuoteI think this extraction of R has now been demonstrated to be possible with the online info and my test results. In my example with the 1uF WIMA cap, the ESR was about 90 times lower than the reactance. Yet this method gave pretty good results.You claimed the reactance has to be << than R which is obviously wrong by at least two orders of magnitude in my example with the 1uF cap.Do you now agree you were quite wrong here?

author: TimFox
author_rank: Super Contributor
timestamp: October 09, 2025, 09:55:45 pm
content: Your first four posts did not specify three voltage measurements, but you did in the fifth post.I can see how the law of cosines could calculate a real and imaginary part; when I have time, I’ll consider the resolution for the “minority component”, ESR in this case, due to subtracting large numbers.My original comments related to using the external resistor to measure the current through the part, then measuring the voltage across the part, giving the impedance magnitude, based on your original description.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 10:44:30 pm
content: Quote from: TimFox on October 09, 2025, 09:55:45 pmGo back and look again. You were still claiming scalar measurements were no good in post #120.QuoteSo you were still wrong in post #120.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 11:11:01 pm
content: QuoteQuoteDo you now accept that this is actually possible?

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2025, 11:12:32 pm
content: Quote from: G0HZU on October 09, 2025, 09:39:55 pmNo, because the 3 Scalar results we got were not even close to the actual value we measured with 2 different capacitors and the 3 Scalar measurements producing results of 395mΩ vs 28mΩ for the LCR meter, which is a factor of >14 in error, also measured the other capacitor as 18mΩ vs 118mΩ. Neither of these 3 scalar measurements are even close to the actual capacitor Rs value and we are using your suggested 1uF film type. We get better results with a T7 than the 3 Scalar techniqueThis confirms what we stated earlier about this measurement technique as it could be sensitive to uncertainties. The fact we can't get values even close to the quality lab grade bench LCR meters indicates this measurement is unrealistic and worthless for any kind of useful purpose. In fact we can't get any useful results with any of the capacitors we've measured with this 3 Scalar technique, and these now include a 1000uF 16V, a 4.4nF Soviet mica, and a 10nF film, all producing results not even close to the IM3536 LCR meter. Suspect this might be due to having to change the frequency and/or the sense resistor for the higher Z capacitors, but still useless!!Anyway, for now we'll stand by what we said and also state what we've found with this 3 Scalar technique, it's worthless for any kind of quality capacitor Rs measurements where semi-accurate results are required.Hopefully others will attempt this technique and report results, maybe even prove us wrongBest

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2025, 11:19:17 pm
content: Quote from: G0HZU on October 09, 2025, 11:11:01 pmYeah, about as possible as measuring the temperature drift and aging of a LTZ1000 with a Simpson VOMBest

author: TimFox
author_rank: Super Contributor
timestamp: October 09, 2025, 11:20:51 pm
content: Quote from: G0HZU on October 09, 2025, 10:44:30 pmOK: my post 120 was in reply to mawyatt's post 119, and I had not noticed your post 117 by then.I'm still dubious about the three-voltage measurement for high-Qcapacitors, but I haven't done the math yet.

author: G0HZU
author_rank: Super Contributor
timestamp: October 09, 2025, 11:46:57 pm
content: Quote from: mawyatt on October 09, 2025, 11:19:17 pmQuoteI've shown you how to extract R when the ESR is less than the reactance and shown you that your schoolboy claim above is wrong and there are plenty of papers about the 3 voltage method online that show your claim to be wrong. By all means conjure up an extreme case where the technology struggles but the same can be done with any measurement technique.QuoteIf it helps this statement is the one that really exposes your ignorance with respect to this 3 voltage technique. You obviously didn't have a clue how it works.Just admit that you were wrong and you weren't aware of this three voltage technique and we can all go home

author: mawyatt
author_rank: Super Contributor
timestamp: October 10, 2025, 12:07:04 am
content: Quote from: gf on October 09, 2025, 09:15:03 pmThis link doesn't agree with the AI Overview response generated when searching "three voltage method impedance". We didn't check the math but the AI shows a result for Zx (Real part of Z) which has the denominator as 2*V2*V3, whereas the gemini link above shows equivalent of 2*V2^2.Need to spend some time looking at the math behind all this, but we threw in the measured values we acquired earlier with the 1uF Film and the result from the gemini solution is still in significant error.Edit: We found another Google AI reference that follows the denominator of 2*V2^2, where V2 is the voltage across the series resistor R or Vref, so this seems correct. We also verified this is correct by means of a simple circuit which evaluated correctly for Rs, the other AI (2*V2*V3) did not. Also noted the Gemini reference has a date of 10/9/2025 at 4:48 PM and published at 5:00PM? Not sure what this means?Best

author: mawyatt
author_rank: Super Contributor
timestamp: October 10, 2025, 01:09:50 am
content: Quote from: G0HZU on October 09, 2025, 11:46:57 pmAnd we've followed your described 3 Scalar method using 2 different quality DMMs (KS34465A and DMM6500), altho we had to search as you wouldn't disclose the details as requested by a couple folks, which hints that you have something to hide, otherwise why not post the requested information to support your claims, and we even utilized the same value and type capacitor 1uF film you claimed along with the same 100Ω sense (actually 99.5158Ω @ 10KHz). Yet our results weren't close to the LCR measurements made by quality LCR meters which both agreed quite well.Since you seem to be hiding something wrt the 3 Scalar computations (multiple requests), we searched on line and now gf has posted another AI link which differs as we mentioned. Which one is correct and what are your results based upon??So basically what you've claimed to have shown doesn't work for us with the same type 1uF film cap and 100Ω sense resistor at same 10kHz and you are still hiding your details after multiple requests, so what's to acknowledge??Best

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 09:47:19 am
content: I'm not trying to hide anything.If you look at my software, I must have looked at this about 10 years ago. I probably generated the excel spreadsheet a year or two before this. So I've had two PCs and several HDDs since then. So I've long since lost my notes on this stuff.However, take a look at the vector diagram below of the three voltages I measured with my Keithley 2015 meter.Do you accept that it is possible to work out the angle shown in the diagram below based on the three voltages that make up the triangle? There should only be one solution for this angle.This is how this system is able to extract vector information from scalar measurements.Once this angle is known then it's possible to work out the magnitude of the reactance and also the ESR using more equations.

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 10:11:03 am
content: I don't have much free time at the moment but the angle can be reverse engineered using the law of cosineshttps://en.wikipedia.org/wiki/Law_of_cosinesI think the cos of the angle is (Vin^2 + Vdelta^2 - Vz^2)/(2*Vin * Vdelta) and this is 0.55425 in this caseThe mag impedance Zm is R*(Vin/Vdelta) which is 18.392 ohmsI think the ESR is then = (Zm * cos(angle) ) - senseR = 0.16 ohmsI hope the above is translated OK as I've worked this out from my spreadsheet.

author: tggzzz
author_rank: Super Contributor
timestamp: October 10, 2025, 10:21:37 am
content: Quote from: mawyatt on October 10, 2025, 12:07:04 amThere ought to be a new axiom to the effect that quoting an AL/LLM response as "proof" automatically loses the argument. Certainly the legal profession is beginning to be forced to realise that.

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 10:30:10 am
content: Anyone with access to an AC simulator can put the network in below for a 1.0397 uF cap with a source (Vin) voltage of 0.753964 V and you should see that Vdelta is about 0.41118V and Vz is about 0.6276V.These are very similar to the 'real' measurements made with my Keithley 2015.Crunch these numbers at 10 kHz with a 10.03 ohm sense resistor and you should get an ESR of about 0.163 ohmsI'm not trying to hide anything here. This technique is decades old. It isn't perfect in the real world but it should be good enough to give a basic confidence check against a low cost LCR meter. Which is what I suggested it could be used for.

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 10:55:21 am
content: QuoteI did warn people that not all online papers on this subject are reliable ***. I went through all this over 10 years ago and found a decent paper on the subject and I made sure that I understood it all and also simulated it as a cross check.*** The same will therefore apply to AI generated stuff.

author: mawyatt
author_rank: Super Contributor
timestamp: October 10, 2025, 11:15:43 am
content: Quote from: G0HZU on October 09, 2025, 11:46:57 pmWill admit we were not aware of this technique, sowrongif that makes you happy, so be it!!However we've just discovered that a Google AI search produced what apparently is a wrong solution for ESR, while another search produced apparently a correct solution (same as Gemini shown by gf) which we verified with a simple circuit and calculation (not simulation).Also, this technique hasn't produced acceptable results yet (considerable error) with the same value and type 1uF film capacitor and 100Ω series resistor at 10kHz (same as what you've shown) when compared with our 2 lab LCR meters, and we utilized a KS34465A or DMM6500 for the 3 scalar voltage measurements. There was a "hint" of this as we glanced over in this article:http://www.metrology.pg.gda.pl/full/2006/M&MS_2006_019.pdfSince we can't reproduce acceptable results (yet), and the method seems viable, we want to understand the root cause of the measurement error source(s).If time permits we'll play around later, and thanks for enlightening usold schoolboywith this methodBest

author: mawyatt
author_rank: Super Contributor
timestamp: October 10, 2025, 11:39:17 am
content: Quote from: G0HZU on October 10, 2025, 10:30:10 amWhy the change to 10Ω sense resistor? Back in post #124 you used 100Ω!Best

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 12:12:47 pm
content: I did the measurements last night in a hurry and my old ESR jig has 1R, 10R, 100R and 1000R sense resistors that can be selected and the exact values are written on the back of the jig as in the image below.10R is a fairly good choice in this case and it was already selected on my jig so I didn't bother to change it. In this case of the 1uF cap at 10kHz, it gives AC voltages that are quite similar for all three voltages.I don't use this jig or the 3 voltage method anymore as I started using an Analog Discovery 2 for LF impedance measurements a few years ago as it is much, much faster. I use the SW produced by 'TheStuffMade'There's a new version available here:

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 12:24:34 pm
content: You can see that my jig uses 4mm sockets for the DVM connections. I connect to the 2015 DVM using a short twisted pair with 4mm connectors. This is less prone to stray pickup and is much more reliable than trying to measure using regular DMM test leads with pointed probes as the DMM probes require some pressure and consistency in order to get stable readings with adequate precision. It's also much easier to use the mouse to drive the GUI on the EeePC. It takes a few seconds to do it this way via the 2015 and GPIB.

author: gf
author_rank: Super Contributor
timestamp: October 10, 2025, 02:04:28 pm
content: Quote from: G0HZU on October 10, 2025, 12:12:47 pmDiscussing with Gemini, the optimal series resistor value (which minimizes the ESR estimation uncertainty for the 3-voltmeter method) seems to be approximately |ZDUT|. This means, for 1µF @10kHz (|Z| ~ 16 Ohm), 10R is likely a better choice than 100R, and 15R should be even better.[ Admittedly, I was unable to follow all of the mathematical details presented by Gemini, so still treat this information with caution and verify yourself. At least I checked plausibility with a few random examples numerically, since I also don't trust LLMs blindly. ]

author: mtwieg
author_rank: Frequent Contributor
timestamp: October 10, 2025, 02:13:52 pm
content: Quote from: tggzzz on October 10, 2025, 10:21:37 amI'm okay with it so long as they verify the result (not by comparing it to another LLM or google search or whatever). But if you go to that trouble, why even mention that you got the answer from an LLM in the first place?

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 02:20:48 pm
content: If it helps boost confidence, I changed the test jig again to let me easily test a single 1uF WIMA and also two in series.So the plots below show the measurements for each of the two 1uF caps and then I put the same two caps in series.The ESR was 0.15R for one cap and 0.16R for the other. Putting them both in series gave 0.314R when measured.See the results below. To me this is a good result. However, I'm using good test gear and taking reasonable care with the test method in terms of connections and I'm using some averaging in the EeePC program for each voltage reading.Don't expect to get results like this if the signal source has spurious signals or if it has a tiny amount of amplitude or frequency drift. Also the sense resistor needs to be measured accurately and a decent voltmeter is required.

author: tggzzz
author_rank: Super Contributor
timestamp: October 10, 2025, 02:27:16 pm
content: Quote from: gf on October 10, 2025, 02:04:28 pmWhen you corrected on of its statements, did it politely apologise profusely before outputting another statement?

author: tggzzz
author_rank: Super Contributor
timestamp: October 10, 2025, 02:31:42 pm
content: Quote from: mtwieg on October 10, 2025, 02:13:52 pmI am perfectly happy with an LLM generatingpossibilitiesthat are thencheckedby acompetenthuman. Example: protein structures and folding for pharmaceuticals.Note that presumes the human is already an expert in the subject. Too manyincompetent humans use LLMs to make seem they are more competent than they really are.

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 03:32:15 pm
content: I modified the jig again to allow easy testing in parallel and put the two 1uF WIMAs in parallel.The result for the ESR was 0.075R and in theory it should have been about 0.078R based on the other two readings.The capacitance was 2.075uF and it should be 1.0344 + 1.040 = 2.0744uF.I'm not sure what else I can do to prove that this is a valid way to measure reactance and ESR.The problem with the internet is that there will always be someone who thinks I am clueless, then someone else might say it all needs to be measured in a 23degC lab with traceable test gear to NIST (or it is all meaningless). Someone else might say the results are still not good enough for them and they have something better. You can't please all of the people all of the time

author: mawyatt
author_rank: Super Contributor
timestamp: October 10, 2025, 05:38:16 pm
content: Quote from: G0HZU on October 10, 2025, 10:11:03 amThis doesn't agree with the Gemini result gf pointed out earlier.https://gemini.google.com/share/c2a7524730d0and also another result from Google AI which was also different from another AI result gathered earlier.Anyway, we just applied your solution above to measurements we just made:Vin = 1.00025Vdelta =0.98727Vz = 0.15755R = 99.5ΩWe get Rs = 99.55ΩWith the method mentioned in Gemini, we get Rs = 49.8mΩThis is from a 1uF film at 10KHz with measured Rs = 28.2mΩ and shown below.Edit: Think we found your problem:(Vin^2+Vdelta^2 - Vz^2)/(2*Vin * Vdelta), should be(Vin^2-Vdelta^2 - Vz^2)/(2*Vin * Vdelta)With thiserrorcorrected we get a more reasonable Rs of 49.8mΩNow the Rs solution is [(Vin^2 - Vdelta^2 - Vz^2)/(2*Vin * Vdelta)]*[R(Vin/Vdelta] which equals:Rs =R(Vin^2 - Vdelta^2 - Vz^2)/(2* Vdelta^2)which is the equation from Gemini.Take a look.Anyway, still a way off from the actual Rs value and certainly not of any use for our needs as the handheld DER5000 shows 0.02~0.03Ω Rs at 10kHz and the cheap Zoyi ZT-MD1 Tweezers show 26mΩ at 10kHz for the same 1uF Film capacitor shown below and these meters take just 10 seconds to use without any computationsBest

author: gamalot
author_rank: Super Contributor
timestamp: October 10, 2025, 05:56:15 pm
content: Here's some Python code I got from Copilot, just for reference.Code:import mathdef calculate_esr(V_dut, V_ref, V_total, R_ref):# Step 1: Calculate currentI = V_ref / R_ref# Step 2: Calculate impedance magnitude of DUTZ_dut_mag = V_dut / I# Step 3: Calculate cosine of phase angle using law of cosinescos_phi = (V_total**2 - V_ref**2 - V_dut**2) / (2 * V_ref * V_dut)# Clamp cos_phi to [-1, 1] to avoid math domain errorscos_phi = max(min(cos_phi, 1), -1)# Step 4: Calculate ESR (real part of impedance)ESR = Z_dut_mag * cos_phireturn ESR# Example usage:V_dut = 0.15755 # Volts across DUTV_ref = 0.98727 # Volts across reference resistorV_total = 1.00025 # Volts across DUT + referenceR_ref = 99.5 # Reference resistor in ohmsesr = calculate_esr(V_dut, V_ref, V_total, R_ref)print(f"Estimated ESR: {esr:.4f} Ω")and the output I got:Estimated ESR: 0.0498 Ω

author: gf
author_rank: Super Contributor
timestamp: October 10, 2025, 07:54:00 pm
content: Quote from: mawyatt on October 10, 2025, 05:38:16 pmI think you are just facing uncertainty propagation (amplification).Small errors of the measured voltages result in a huge change of the estimated/calculated ESR.Your DUT has a high Q > 500, and your choice of R is not optimal either. Both lead to high uncertainty amplification.You can try an R with about 15Ω; it should improve ESR uncertainty (but still don't expect wonders).How accurate can you measure the voltages?If your voltage readings have an accuracy of (say) 0.1%, you could for example calculate ESR from each of the 8 combinations{ Vin*0.999, Vdelta*0.999, Vz*0.999 }{ Vin*0.999, Vdelta*0.999, Vz*1.001 }{ Vin*0.999, Vdelta*1.001, Vz*0.999 }{ Vin*0.999, Vdelta*1.001, Vz*1.001 }{ Vin*1.001, Vdelta*0.999, Vz*0.999 }{ Vin*1.001, Vdelta*0.999, Vz*1.001 }{ Vin*1.001, Vdelta*1.001, Vz*0.999 }{ Vin*1.001, Vdelta*1.001, Vz*1.001 }and the pick the lowest and highest ESR estimate to obtain the interval within which the actual ESR will likely be.

author: golden_labels
author_rank: Super Contributor
timestamp: October 10, 2025, 08:23:31 pm
content: I avoided replying to this tangent, but it’s also hard to ignore a half hundred posts. I can’t even unsubscribe, since the main thread is mine.What did I see? Curiosities, my friends, curiosities. First, regardless of him being right, through a poor choice of arguments a user of 3k+ posts almost made himself look like these people claiming they built a free energy device. Second, now people talk about what LLMs randomize, instead of just asking G0HZU to copy-paste the formula from his spreadsheet. Weird world, I tell you, weird!The equation:We’re on an engineering forum, so I’m going to start with the technical part.The method is quicklyexplained by Iacopo Giangrandi here, and onpages 472–475 “А Text Book of Practical Physics” by Sharma, Singh, Prasad (1986).The measurement gives us the phase angle and apparent power. ESR is the real part of it.I don’t comment on accuracy, only on the equations used.The miscommunication:What can we learn from a few dozen posts?ECREEapplies even where claims are not that extraordinary. It’s enough they don’t fit into a commonly held belief one stands against.Appealing to one’s own expertise is no good, if facing other experienced people. That’s only a valid approach with newbies.Anybody can show results. In engineering debate it’s the guts that matter.Pointing to person’s mistakes is often necessary; criticizing a person is also valid. But it’s a thin and dangerous line to walk on, if other trouble with argumentation already pile up. One misstep and everybody thinks it’s ad hominem.Directing to search engines is only good, when it’s about basic knowledge mentioned literally everywhere. For relatively obscure topics, you have no control over what the algorithm decides to show to another person.

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 08:52:37 pm
content: In my defence I really didn't expect anyone to disagree so strongly. I've gone back to the very first example I gave where I simulated it and put the simulated results into a spreadsheet.I've added the vector diagram below and hopefully this helps. I've gone through the equations in the spreadsheet and the VB6 program and it's really easy to get in a muddle with the law of cosines but I do still think my spreadsheet is OK. I don't understand why Mawyatt didn't just use the simulation data I provided as this removes the uncertainty from his test gear etc. I'm trying to remember this stuff from over 10 years ago and I think I've now got the vector diagram correct below.A sense resistor of 100 ohms is not ideal here but I've left it like this as it doesn't matter with a simulation. It would be better to use 10R or 15R as suggested elsewhere as this would help minimise uncertainty when using real test gear.Maybe Mawyatt can use the voltages in the simulation below to check his calculations? You can see that the measured voltages in the simulation do produce an ESR of 0.10 ohm with my spreadsheet

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 09:26:20 pm
content: Quote from: G0HZU on October 10, 2025, 10:11:03 amIn the case with the 100R sense resistor and a 1uF cap with 0.100R ESR I think the numbers crunch out as below:cos = (Vin^2 + Vdelta^2 - Vz^2)/(2*Vin * Vdelta) = (1^2 + 0.9866^2 - 0.15703^2)/(2*1*0.9866) = 0.987594The total mag impedance Zm is R*(Vin/Vdelta) which is 100*(1/0.9866) = 101.3582 ohmsThe ESR is then = (Zm * cos(angle) ) - senseR = (101.3582*0.987594)-100 = 0.1008 ohmsThis is close enough to 0.1 ohms despite me limiting the decimal places of the voltage measurements.Yet Mawyatt still insists the equation I provided produces an ESR that is wrong by several orders of magnitude?Why doesn't Mawyatt just use my data to check the equations or use a simulator to generate his own data and then check my equations?

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 10:07:25 pm
content: Vin = 1.00025Vdelta =0.98727Vz = 0.15755R = 99.5ΩMawyatt's measured data above fed into my equation (and my spreadsheet) also gives an ESR of 0.0498 ohms so I don't see why the equations below need editing as suggested by Mawyatt?cos = (Vin^2 + Vdelta^2 - Vz^2)/(2*Vin * Vdelta) = (1.00025^2 + 0.98727^2 - 0.15755^2)/(2*1.00025*0.98727) = 0.987517The total mag impedance Zm is R*(Vin/Vdelta) which is 99.5*(1.00025/0.98727) = 100.80816 ohmsThe ESR is then = (Zm * cos(angle) ) - senseR = (100.80816*0.987517)-99.5 = 0.0498 ohms

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 10:25:30 pm
content: Try measuring it again with a 10R sense resistor. I think this should minimise uncertainty.Then when this is done, also try measuring caps in series and parallel like I did. Try adding a 0.1R resistor in series like I did. Compare the results to the other meters.You will need to do things to minimise uncertainty and the change to a 10R or maybe 12R or 15R should help here. But this is a much stricter test than I initially proposed which was for a basic sanity check for an ESR of 0.1R against a low cost ESR meter.You are testing an ultra low ESR cap here if the true ESR of your 1uF cap is just 0.028 ohms at 10kHz. Can you provide details about this cap? Can I buy one from Farnell or Mouser?

author: mawyatt
author_rank: Super Contributor
timestamp: October 10, 2025, 11:15:16 pm
content: Quote from: gf on October 10, 2025, 07:54:00 pmWe just used the same type 1uF cap and value R (100Ω) as GOHZU used to remove as many "uncertainties" as practical. Our voltage measurements were with a KS34465A and a DMM6500 which is the best DMMs we have, we also made all 3 measurements for a given "session" with the same meter to help.Results were/are quite disappointing and likely due to the extreme sensitivity of the 3 Scalar method to measurement uncertainty which we mentioned awhile back.Anyway, the original statement in post #107 from GOHZU claimed the method should produce good accuracy and allow cross checking handheld LCR Meters. This wasn't the case with our results after multiple attempts (we've spend enough time on this already), so hopefully others will have better success than we've achieved.It is an interesting concept that we hadn't heard about which was our reason for questioning the validity of such, and still not convinced it's worthwhile today with all the affordable LCR handhelds available based upon the autobridge technique.Best

author: G0HZU
author_rank: Super Contributor
timestamp: October 10, 2025, 11:44:52 pm
content: So no explanation from Maywatt as to why he claimed my equation was wrong. No surprise there.Quote100R isn't the best choice if you want to minimise uncertainty when using real test gear especially if you want to explore really low ESR caps.So far we've had total denial from Maywatt that this technique is even possible even when I explained that 3 scalar voltages can be used to reverse engineer vector measurements. Mawyatt still couldn't see how this could be done.Then when the penny dropped that it is possible, he said it was like measuring drift on a $$$ voltage reference with a Simpson meter. That's obviously ridiculous.Now his dismissal of the technology seems to be based on testing a much lower ESR cap still using a (less than ideal) 100R sense resistor because that sense resistor value was shown in my initial concept spreadsheet. This was the spreadsheet that Mawyatt falsely claimed to have incorrect equations.I've shown that it can measure ESR of a 1uF cap at 10 kHz quite well down to about 0.15R. But that's the lowest ESR 1uF cap I have here. Putting two in parallel gave good results too where the ESR dropped to just under 0.08 ohms.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 01:05:56 am
content: Quote from: G0HZU on October 10, 2025, 10:25:30 pmFrom post 133Quotehttp://www.knscha.com/en/emisuppressioncapacitors/knscha-mpx/mkp-x2-capacitor.html

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 01:53:40 am
content: If you just want to test something with a low ESR and higher capacitance, Mouser does carry these.My BK and cheap VNAs using shunt through will not get down this low.***This particular part has a typical ESR of 4mohm.https://www.mouser.com/ProductDetail/Knowles-Illinois-Capacitor/940C8W1P5K-F?qs=VVYaXoEjsFboCN1B1JlUdw%3D%3D***Attempted to measure two of these same caps in parallel. ESR measures below one count.

author: mawyatt
author_rank: Super Contributor
timestamp: October 11, 2025, 02:27:23 am
content: Quote from: G0HZU on October 10, 2025, 11:44:52 pmNo total denial as GOHZU claims, here's what was posted on 10/9 #154Will admit we were not aware of this technique, so wrong if that makes you happy, so be it!!Best

author: mawyatt
author_rank: Super Contributor
timestamp: October 11, 2025, 03:33:57 am
content: Quote from: G0HZU on October 10, 2025, 11:44:52 pmGOHZU also claimed in post #107"At low frequencies (<300kHz) and with reasonably large capacitors, (>100nF?) it is possible to measure ESR quite well using a clean signal source and a known series sense resistor in series with the DUT capacitor with the far end of the DUT cap grounded. Then measure the AC voltages around the sense resistor using a decent (true RMS reading) DVM. Something like a Keithley 2000/2015 or an Agilent 34401A bench DVM would be ideal here."So far what GOHZU has shown is a method that we can't reproduce acceptable results using similar DUT 1uF film cap and sense resistor of 100Ω which was initially used and a KS34465A or DMM6500. Now GOHZU claims a lower resistor is required as per gf recommendations. Why wasn't this lower value initially used by GOHZU??We just repeated the test with a 10Ω resistor (don't have a 15Ω as gf recommended), here's the measurements at 10kHz of the same 1uF 28.2mΩ film capacitor used before with R = 100Ω.R = 9.9630Ω measured at 10kHzVin = 0.49945VVdelta = 0.26564VVz = 0.42318VWe've repeated the measurements a few times with the same result, negative Rs results from GOHZO solution (and Gemini)!!So we've followed GOHZU expert advise, tried using similar 1uF film test capacitors, used both a KS34465A and DMM6500 for measurements, with the SDG2042X AWG as the 10kHz source, and done so with 100Ω and now with recommend lower value 10Ω sense R. Yet our results are disappointing in one case (100Ω) and ridiculous in another (10Ω), The test capacitor (CBB22 105J400) was measured with a Hioki IM3536 and TH2830 both at 1Vrms and both agree very well in both C and Rs at 10kHz.Anyway, we'll avoid using this method as described by GOHZU until someone else can make some sense out of this and create useful results, we certainly can't!! Even if the method did produce acceptable results, it doesn't for us, we likely wouldn't use it as it's too cumbersome and time consuming when one can just grab a handheld LCR meter for the task at hand. Most seem to be based upon the Auto-Balance-Bridge method common to Lab Grade Bench LCR Meters, even some the latest cheap LCR Tweezers employ this techniqueEdit: Hopefully others will give this 3 Scalar Technique described by GOHZU a try, we've tried and tried to make it work, but the results continue to be disappointing. It seems the technique is highly sensitive to slight uncertainty in measurement, which is aggravated by higher "Q" capacitors, and unfortunate as high "Q" components are where it could be beneficial.Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 05:00:31 am
content: Quote from: mawyatt on October 11, 2025, 03:33:57 amSo no program or spreadsheet...Quote from: G0HZU on October 10, 2025, 10:07:25 pmUsing the numbers above to double check. Late and no coffee.... Seems fine.I had let the equipment warm up and took measurements using 1, 10 & 100 ohms with the first 1.5uF PP cap, sine @ 10kHz, HP34401A used for measurements. I seem to have created free energy.I have an old Fluke thermal RMS meter I saved from the e-waste and my old Marconi will run down to 10kHz. Maybe I'll remeasure using that setup.***There was an error in my setup for the 1 ohm. I have updated the data to reflect that.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 06:06:54 am
content: Repeating the test using Marconi 2024 RF generator set to 10kHz and Fluke 8506A meter. The results are similar. More free energy...It's late and very possible I am not understanding something or fucked up my measurements. Seemed straight forward and my calcs seemed to match with G0HZU's post.Feel free to ask any questions you have about the setup.

author: tggzzz
author_rank: Super Contributor
timestamp: October 11, 2025, 07:47:31 am
content: Could somebody who has bothered to set up a spreadsheet report the results of a trivial sensitivity analysis.By "trivial" I mean don't bother doing it properly by analysing the equations or running a monte carlo analysis. Just permuting each of the inputs by 0.1% and reporting how much the results change would be a useful starting point.Bonus points for doing that with a range of components, e.g. good/bad electrolytics, a high Q capacitor.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 08:16:25 am
content: Quote from: G0HZU on October 10, 2025, 10:25:30 pmQuote from: gf on October 10, 2025, 07:54:00 pmThe Xc for 1.5uF @ 10k is about 10.6. I tried it with a closer match as suggested. Just another negative ESR added to the list. Added notes to keep track of what these tests were.***Added photo of the test setup. 1,9,90,900 ohm and added 0.5 ohm for last test (allows 1,10, 10.5, 100 & 1k per G0HZU). Clip leads attach to the RF generator were used for all tests. Resistors were measured with Kelvin leads using HP34401A.Forgot to add file. It was way past my bedtime.

author: gamalot
author_rank: Super Contributor
timestamp: October 11, 2025, 01:10:24 pm
content: Quote from: mawyatt on October 11, 2025, 03:33:57 amI tried testing metallized polypropylene film capacitors using different combinations of signal sources and multimeters, but the results were disappointing. It's pretty clear that while the method makes sense in theory, in practice it’s limited by measurement accuracy and just doesn't give reliable results.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 02:52:39 pm
content: A fresh day, and decided to give GOHZU's suggestion one more try with something with a much higher ESR. The part I used is a SEACOR 1uF MMWA PE (Polyester). This part measures 0.238 ohms ESR at 10kHz. I used the same resistors soldered to the cap and the HP34401A. Same software but flushed out all the data to avoid adding confusion.The ESR values are at least not negative.If this technique does work as suggested, I have something major wrong with my setup / understanding how to measure, or the there is a problem with the monkey math.

author: tggzzz
author_rank: Super Contributor
timestamp: October 11, 2025, 03:17:38 pm
content: Quote from: joeqsmith on October 11, 2025, 02:52:39 pmOr the method is too sensitive to the reading accuracy. A simple sensitivity analysis would indicate whether or not that is an issue.The spreadsheet calculations are, I believe, not complex. It would be helpful if G0HZU (for example) could cut and paste each of his equations into a post here. That would make them visible, explicit, and others can sanity check them in a spreadsheet of their choosing.

author: gf
author_rank: Super Contributor
timestamp: October 11, 2025, 04:11:38 pm
content: Quote from: tggzzz on October 11, 2025, 03:17:38 pmUndoubtedly, it is very sensitive, and sensitivity is approx. proportional to Q.However, for Joe's latest numbers to become plausible (such that ground truth value falls within the ESR estimation uncertainty bounds), I must assume that Joe's voltage readings have an uncertainty as large as > 0.2%. OTOH, mavyatt's numbers were still plausible if I assume 0.1% measurement accuracy (albeit they were useless in practice, too).

author: mawyatt
author_rank: Super Contributor
timestamp: October 11, 2025, 04:15:55 pm
content: This is beginning to reveal why we hadn't heard of the 3 Scalar Measurement technique GOHZU brought up. Evidently it's too sensitive to measurement uncertainty with higher "Q" components to be of any practical value with the components represented, discussed and measured here by multiple folks.We've tried various capacitors with different sensing resistors with a pair of quality DMMs and best case still almost 2X off the Lab Bench LCR Meter measured Rs value, and we even discovered a few of the "Free Energy" capacitorsWish GOHZU would showin detailthe expert measurement, math, (spread sheet) techniques applied to achieve the remarkable results GOHZU has shown, we certainly can't achieve this level of performance and seems others can't either!!BTW we just did another "round" of measurements using a 0.1uF and another type 1uF film capacitor, results were the same!!Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 06:18:05 pm
content: Quote from: G0HZU on October 10, 2025, 02:20:48 pmI want to be clear that none of my home equipment is in calibration. It's just a hobby of mine and I have no need for it. I do not own an ACV standard but attached showing a SHALLX 2.3 ohm resistor, a Vishay 60 ohm 0.005% S102K resistor, Fluke 731B voltage reference set to 1 and 10VDC.The Fluke thermal RMS meter (which I have never attempted to align) reads very close to the HP. I did have the HP and Marconi in for calibration with a report in 2016 and everything was fine. You mentioned frequency and amplitude drift. My signal generators use a GPS with double ovenized oscillator for a time reference. That system runs 24/7.The spectral purity is as follows:Harmonics: Typically better than -30 dBc for RF levels up to +7 dBmTypically better than -25 dBc forRF levels up to +13 dBmNon-harmonics: Better than -70 dBc for carrier frequencies up to 1 GHzTo plot the amplitude drift, the HP34401A was attached directly to the RF generator, which was set to 10kHz. Shown is the drift over a 10 minute period, assuming I am very slow at taking these measurements. For a 1V signal, about 70uV of drift. Really thought, it maybe takes me 2 minutes to make all three readings. (plus it will settle as the temps stabilize)Maybe my setup just isn't up to your requirements that would allow me to get an accurate ESR measurement using this technique. The values I get are not even remotely reasonable. I need more details.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 06:57:19 pm
content: My Signal Hound is spec'ed to operate down to 9kHz. It uses the GPS like all of my equipment. Note that the previous harmonic plot shows the fundamental at 9.994595kHz rather than the expected 10.000000kHz.10k_GPS: Showing generator attached to counter. Both referenced to the GPS.10MHz_GPSref: Attaching the Signal Hounds 10MHz reference cable to the frequency counter.1MHz_GPStest: Setting the RF generator to 1MHz and measuring with the Signal Hound.Appears the Signal Hound has a bit of a problem with frequency accuracy when using it down this low. Not a problem for me but something to be aware of.

author: mawyatt
author_rank: Super Contributor
timestamp: October 11, 2025, 07:13:28 pm
content: @ JoeThink your equipment, method and setup are fine, it's just this method is highly sensitive to any measurement uncertainty with high "Q" components. Having something which shows how the result uncertainty behaves with DUT component "Q", Frequency and Sense Resistor would be highly beneficial to all!!Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 11, 2025, 07:53:15 pm
content: Quote from: mawyatt on October 11, 2025, 07:13:28 pmThis thread and the one it referenced started with film caps. Q was brought up by Tim and G0HZU claimed "none of that matters".Quote from: G0HZU on October 08, 2025, 11:56:54 pmI am expecting G0HZU to chime in to demonstrate in detail what I am doing wrong as they have been very clear that this method gives good results when used within their constraints. After all, it was important to them for members to admit they were wrong, suggesting they are right. I am the king of fuckups and have no problems with them pointing out my mistakes. So give them a chance to respond.Quote from: G0HZU on October 09, 2025, 07:45:43 pmObviously, I soldered the crap out of this thing, completely ignoring your warning. I also don't have my calibrated beech towel out like I normally would for sensitive experiments. Maybe the small air drafts are causing a problem. Resistors are all low tempco, but maybe you are using something more stable.Shown looking at 10 minutes of data for both Vz and Vdelta with that SEACOR PE cap.***QuoteMaybe 5 digits of no drift...One thing I can tell you is that the time to run this simple experiment, I could have measured a life time of caps with my cheap RLC meter and got reasonable results.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 11, 2025, 08:26:07 pm
content: The ESR measuring way I like it the most is the one in which a square wave of constant current (not voltage) is pushed through the DUT, then a synchronous detector measures the voltage "jumps" for either +I and -I, which jumps are proportional with the series resistor only, so independent of the capacitance.Seen that method long ago, in a 'Make' magazine, and gave it a try a months ago, out of curiosity. It's the schematic in the most upper-right corner in this selection of most common ESR meters:

author: mawyatt
author_rank: Super Contributor
timestamp: October 11, 2025, 11:53:54 pm
content: Quote from: joeqsmith on October 11, 2025, 07:53:15 pmBelieve "Q" does matter as thisinverselyindicates the relative magnitude of the Real and Imaginary parts of the DUT Impedance Z. Which becomes increasingly difficult to separate with this Scalar technique (requiring subtraction of almost identical scalar values in high "Q" cases), whereas having Phase as another Z variable with the Auto-Balance-Bridge Technique allows extraction of the Real part of Z with better fidelity and why this is so popular now with all sorts of LCR Meters/Tweezers today.Best

author: mawyatt
author_rank: Super Contributor
timestamp: October 11, 2025, 11:59:11 pm
content: Quote from: RoGeorge on October 11, 2025, 08:26:07 pmYes the "Pulse Technique" has been around for awhile. We've used this in the distant past to sort caps by which had the lowest edge step response while watching on an analog scope when no proper LCR meter was available.Best

author: gf
author_rank: Super Contributor
timestamp: October 12, 2025, 12:25:46 am
content: Quote from: mawyatt on October 11, 2025, 07:13:28 pmUncertainty propagation according to GUM LPU. I hope it's correct. Please forgive mistakes.[ Must admit that I got again help from Gemini, but tried to check derivation steps as good as I can. ]Assumptions/approximations:high-Quality Factor (Q≫1)equal relative uncertainty for the voltage measurements (ur​)ignoring uncertainty of RStandard uncertainty (absolute, in Ohms):uc(ESR) ≈ (sqrt(2) * ur / R) * sqrt(R^4 + R^2 * |Z|^2 + |Z|^4)Standard uncertainty if R = |Z| (optimal R):uc(ESR) ≈ sqrt(6) * ur * |X| oruc(ESR) ≈ sqrt(6) * ur * |Z| since |Z| ≈ |X| when Q>>1Relative uncertainty (ur(ESR) = ΔESR/ESR):ur(ESR) ≈ (sqrt(2) * Q * ur) / (R * |Z|) * sqrt(R^4 + R^2 * |Z|^2 + |Z|^4)Relative uncertainty if R = |Z| (optimal R):ur(ESR) ≈ sqrt(6) * Q * urQuote from: mawyatt on October 11, 2025, 11:53:54 pmRelative uncertainty (ΔESR/ESR) is approx. proportional to Q. Absolute uncertainty (in Ohms) is approx. proportional to |Z| ≈ |X|, independent of Q. But in the end it won't help either if absolute uncertainty is 100mOhm, independent of Q, if you want to measure an ESR of 10mOhm. So Q still matters indirectly.

author: mawyatt
author_rank: Super Contributor
timestamp: October 12, 2025, 01:09:41 am
content: Intuitively this makes sense, the higher the "Q" the more difficult accurate RS extraction becomes with the Scalar method.Actually this apparently is also true for the methods involving Phase measurement as the Phase becomes increasing close to 90 degrees as "Q" rises, however these methods have additional information benefits for signal processing and the results show.This brings up an interesting thought experiment (or actual experiment if anyone wants to attempt such), if one employed synchronous detection (using the source as the synchronous reference source) to reduce the influence ofnoise or interferrence, this should yield lower uncertainty in the 3 Scalar measurements and improve the measurements.Anyway, thanks gf for posting this, wish we knew how to use this AI stuff better, we'll just learn as we go along until the "door shuts"Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 12, 2025, 02:40:06 am
content: 1uf tant with lower Q and higher ESR. At least it is a positive value for ESR but a long way off from the BK.***Setup had been turned off and things are warming up, so I took a second measurement to see the effects (added after original). There's some difference but it doesn't explain the error I am seeing.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 12, 2025, 03:24:12 am
content: Maybe I missed it but I don't see where G0HZU did any cross comparisons to a known meter. They measure parts, place them in series/parallel but we really have no absolute values to compare these with.My BK RLC meter, like everything else is not in cal. Also, like most of my equipment, it was in need of repairs (thanks to BK for helping out with the details). Shown measuring ESR with that same SHALLX 2.3 ohm resistor attacked to the BK. This is the same component I previously measured with the HP34401A.***Updated photo to show 10kHz rather than 1k, and I inserted the resistor as far as I could (lowered it 0.002 ohms). This resistor is very close to the ESR measured with the Tant.***As one last sanity check I soldered the SHALLX 2.3 ohm resistor into the fixture. Results are close to what was measured directly with the BK and HP.At 10kHz we can assume everything is purely resistive. IR = Vdelta/R = 0.407113/9.9892 = 0.0407553A. ESR = Vdelta/IR = 0.0932924/0.0407553 = 2.28909 ohms (measured 2.301). Vdelta + Vz = Vin, 0.407113 + 0.0932924 = 0.500405 (measured 0.500846)Some errors in my measurements but seems reasonable.

author: tggzzz
author_rank: Super Contributor
timestamp: October 12, 2025, 09:17:54 am
content: Quote from: mawyatt on October 11, 2025, 11:59:11 pmJust so.It has several good points: it shows what is relevant in SMPS and decoupling applications, only a sig gen is required, if you add an offset to the sig gen output you can see how MLCCs vary with DC offset.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 12, 2025, 09:25:59 am
content: w2aew made a video about the generator+oscilloscope ESR measuring method:#135: Measure Capacitor ESR with an Oscilloscope and Function Generatorw2aewLong ago I used to have a 555 to generate square pulses, to visualise the ESR on an analog 20MHz oscilloscope.

author: tggzzz
author_rank: Super Contributor
timestamp: October 12, 2025, 09:28:28 am
content: Quote from: mawyatt on October 12, 2025, 01:09:41 amThis is a nuanced assessment from somebody who continually looks for new tools because heknowshis research field (biochemistry)desperatelyneeds new tools.https://www.science.org/content/blog-post/evaluation-deep-research-performanceObviously the field is different, but that allowusto concentrate on the essential features of LLMs, and continue to see the wood rather than getting lost in the trees. Any post referencing Humpty Dumpty is getting off to a good startAside: if you want to relax with some droll hair-raising tales, see Lowe'shttps://www.science.org/topic/blog-category/things-i-wont-work-withExample: "Sand Won't Save You This Time", from fires, that is.

author: armandine2
author_rank: Frequent Contributor
timestamp: October 12, 2025, 10:21:36 am
content: Quote from: mawyatt on October 11, 2025, 07:13:28 pm...I managed to find the right capacitor to test - low Q and showing an appreciable loss angle.measured with DER EE LCR meter DE-5000 - 87.2 degrees....the three voltmeter method worked pretty good, I calculated angles between 87.3 - 87.6, four sets of readings....I chose my sense resistor to match Xc of Capacitor at 10kHz - 27 ohm close to optimal 29 ohm (a textbook recommendation)....DMM used Keithley 2015, Sig Gen Keysight EDU33212A

author: joeqsmith
author_rank: Super Contributor
timestamp: October 12, 2025, 02:37:59 pm
content: Quote from: armandine2 on October 12, 2025, 10:21:36 amI think you deserve an award for finding a component that yields the closest results when measured this way!!

author: armandine2
author_rank: Frequent Contributor
timestamp: October 12, 2025, 03:18:41 pm
content: ..I'll take that...the method appears to have a flaw regarding its usefulness

author: gamalot
author_rank: Super Contributor
timestamp: October 12, 2025, 03:24:31 pm
content: Quote from: armandine2 on October 12, 2025, 03:18:41 pm

author: joeqsmith
author_rank: Super Contributor
timestamp: October 12, 2025, 05:12:51 pm
content: So in summary, your golden award cap measured as follows.Capacitance: 545 nFESR: 1.37 ohmsQ: 21.2Phase: -87.2 degXc = 29.2, and you used a 27.2 ohm resistor for the reference and got 1.327 ohm ESR.Compare this to the last Tant capacitor I attempted to measure using G0HZU's suggested technique.Capacitance: 984 nFESR: 2.016 ohmsQ: 8.023Phase: -82.93 degXc = 16, I used a 10 ohm resistor, and got 1.74 ohm ESR. I would have expected the Tant would have been much easier to measure. The big difference in your golden setup is how close your reference resistor is matched.Using 984nF, Xc @ 10kHz = 16.17 ohms. I have some 10 ohm and put together 2 in parallel (5 ohms), in series with a 10 (15 ohms). I place that 15 ohms in parallel with 10 ohms (15*10/(15+10) = 6ohms). I then placed that 6 ohms in series with a 10 ohm to get me 16 ohms total. Twisted it all together but could not resists the temptation to solder the mess. Measures 16.0782 ohms. Note I twisted the last resistor's lead around the tant caps lead and again, soldered.I took the measurement with the generator cold, then after 10 minutes and again after a half hour warmup. Results now very similar to your golden setup.***After an hour of warmup, ESR measurement continues to tighten up.

author: mawyatt
author_rank: Super Contributor
timestamp: October 12, 2025, 07:19:37 pm
content: What if you adjust the measurement frequency until the Scalar voltage across the DUT equals the Scalar voltage across R, thus Vdut = Vr and the result simplifies to:Rs ~ R(V^2 -2*Vdut^2)/(2*Vdut^2) or R{(V^2/2*Vdut^2) -1}Edit: Grabbed the only low value low Q cap we have in front of us a 10uF 160V Electrolytic.Results of equal Vdut and Vr at 1.895kHz yields:Rs of 4.33Ω and measured valued 4.303Ω and 9.3578uF.Grabbed another low Q cap, 100uF 160V Electrolytic.Rs of 0.583Ω calculated from above and 0.5925Ω 93.768uF measured at 170.45HzWith a high "Q" cap the results were not as good, Rs = 19.0mΩ vs 28.7mΩ measured for 991.838nF Film type at 16.094kHz.So this technique above, making the DMM readings for Vdut and Vr equal by changing frequency seems to work with low Q capacitors.Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 12, 2025, 07:29:11 pm
content: The SEACOR 1uF PE (polyester) part measuredCapacitance: 970.9 nFESR: 0.238 ohmsQ: 71.59Phase: -89.19 degWhen previously tested using the 10ohm resistor, ESR measured 0.08. At least it was a positive number. Xc is 16.39 @ 10kHz. Using the same 10ohm resistors (I have a full bag of these things), place 3 in series for 30 ohms. Parallel with 10 = 7.5 ohms. Place the 7.5 in series with 10 gets us 17.5 ohms. Place the 17.5 in parallel with 10 gets us 6.364 ohms. Add that to another 10, gives us 16.364 ohms. Building this mess required some heat shrink to keep the parts separated. Ended up at 16.2359 ohms.I measured it twice, 10 minutes apart and results are now much closer to what the BK measured.

author: mtwieg
author_rank: Frequent Contributor
timestamp: October 12, 2025, 11:25:10 pm
content: Quote from: mawyatt on October 12, 2025, 07:19:37 pmSure, that will likely give a better uncertainty in the ESR measurement at that frequency.But since, as previously discussed, ESR varies a great deal with frequency, there are good reasons to measure ESR/Q as specific frequencies (like 1kHz or 120Hz, etc). Again this goes back to what we're using the capacitor for, and why ESR/Q matters.

author: mawyatt
author_rank: Super Contributor
timestamp: October 13, 2025, 12:27:27 am
content: Quote from: mtwieg on October 12, 2025, 11:25:10 pmThat does seem to be the case with low "Q" capacitors.QuoteHowever,somehigher "Q" capacitors seem to have less RS (ESR) frequency influence as shown belowBTW these aren't someexotic expensivecaps, the first two are about the cheapest film caps available, and the third is a surplus 1uF PP 600V large tubular type.Note how "Q" dives at resonance as it should, since "Q" = Imaginary/Real parts of Z and at resonance the Imaginary part is zero and "Q" approaches zero!Edit: Added a couple cheap low "Q" Electrolytics (10uF and 100uF) which are somewhat well behaved wrt RS (ESR) and frequency behavior, especially above ~100Hz!As always YMMV!!Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 13, 2025, 07:32:44 pm
content: Verifying GOHZU's application and spreadsheet, the only problem I noticed was the spreadsheet current is in Amps not mA.Quote from: G0HZU on October 09, 2025, 08:37:45 pmI wasn't sure what they were doing there so I did not attempt to verify this part. I also verified that the link provided for the Gemini solution matches with G0HZU's calculations.It appears they were automating the measurements but constraining the reference to 1k,100,10 or 1 ohms seems like a huge mistake on their part. If they did not have access to a good RLC meter and were using the data that this program was spitting out,

author: joeqsmith
author_rank: Super Contributor
timestamp: October 13, 2025, 09:22:51 pm
content: I added phase to their calculations. Using the data I collected with the matched reference resistor, after an hour of warmup for the 1uF Tant, compared with the BK.When I measured that SEACOR 1uF PE part, I wonder now if my seven resistor network is causing some error.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 14, 2025, 01:05:45 am
content: I sorted 2X33ohm resistors in parallel rather than the 10ohm network. Ideal would be 16.39 ohms. HP34401A measured 16.337 ohms. I then repeated the measurements. Results are much closer to the measured values, not.***Plan is to next remeasure that 1.5uF PP part. My BK reads over range Q and the ESR is unstable at 100Hz with that part.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 14, 2025, 02:37:20 pm
content: I downloaded the DE-5000 manual and can't seem to find the limits for the Q measurement. Does anyone here have that information?I am thinking to test that 1.5uF PP, high Q part at 100,1k,10k & 100kHz. My BK can not read Q or ESR at 100Hz and it does not offer 100kHz.

author: mawyatt
author_rank: Super Contributor
timestamp: October 14, 2025, 03:08:35 pm
content: Believe it's 2000 with DER5000.We can't measure "Q" at 100, 120, 1k or 10kHz with a PP 1uF film cap, it only shows "Q" at 100kHz. The IM3536 can measure "Q" to 20,000.Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 14, 2025, 04:29:30 pm
content: Thanks. I looked at a new handheld BK. They talk about it being 40k counts for the primary display, which can display Q.The Q for that part I want to test is over 10,000 at 100Hz (limit of my BK). I'll measure it at work along with the resistors. Maybe at the different frequencies, or tightly matched references, we can make some sense of the measurements (at least get a positive value for ESR). Not holding my breath.

author: mawyatt
author_rank: Super Contributor
timestamp: October 14, 2025, 05:54:47 pm
content: Look at the TH2830, this is a really good LCR meter that gives reliable results (with proper technique of course). Think it can also measure "Q" to 10 or 20k and allows frequency selection to 5~6 places. BK rebadges this and the TH2832 I believe.We have a few caps that show over 5k for "Q" at 1kHz, and one we had that was over 10k.Anyway, since RS(ESR) doesn't seem to vary much around a given frequency, using a fixed R with magnitude ~ DUT Z at frequency, then adjusting frequency so you get equal voltage across DUT and R seems to give good results for the low "Q" caps we tried above. Interestingly for high "Q" caps this technique reveals the very high sensitivity of the scalar method, as slight changes in frequency cause reading imbalance.Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 14, 2025, 07:02:46 pm
content: After you mentioned that the first time, I had added the ability to sweep different parameters then feed that into my ESR calcs to get a feel of how it behaved.You certainly could trim the frequency to get the two nodes to balance. However, G0HZU never used that method and they were limited to only those few resistors. Even if you were to trim the frequency, moving the meter back and forth between the two nodes would be a nightmare. You could construct a custom meter to show the null. That said, the whole concept seems majorly flawed no matter how you look at it. It would be very time consuming to setup and measure. It ties up more generic equipment. And you have a bit of a chicken and egg problem. Say the boss hands you a hand full of unmarked parts to measure.Vs buying a low cost LRC meter, insert the DUT and measure.

author: gf
author_rank: Super Contributor
timestamp: October 14, 2025, 11:33:21 pm
content: Quote from: mawyatt on October 14, 2025, 05:54:47 pmHmmm? How is it possible to reliably measure a Q of 10k or 20k when the base accuracy is only 0.05%? I'm struggling to see how that would work. Can you quantify "reliable" in terms of the desired relative uncertainty level of the measured Q or ESR?

author: mawyatt
author_rank: Super Contributor
timestamp: October 15, 2025, 12:49:33 am
content: Quote from: gf on October 14, 2025, 11:33:21 pmDon't believe you can "claim" Q that high as being within that level of meter accuracy, the impedance magnitude Z yes but not the "Q". I'm sure if one dives into the manuals this is probably explained somewhere. Q is displayed up to 10k, then one must use D and evaluate Q as 1/D.At this level "Q" is quite sensitive thecontact effectsas one can "wiggle" the leaded DUT and see the "Q" jump around, whereas the Z remains somewhat stable. Awhile back we developed a type of SMD fixture where the SMD end terminations made the Force and Senses connections to reduce thesecontact effectsas we were having difficulty with very low Z SMD components (<100mΩ).We certainly wouldn't quote a "Q" of many thousands and expect to repeat this later at the same level within these types of meter accuracy.Our one PP 1uF cap that had a IM3536 measured D of 0.00006~0.00008 which is a "Q" of 12 to 17k, and this varied even with the utmost care with Zero Ω Cal and setup between sessions. Another member has a new IM3536 and some very special PP caps custom made, he's achieved D of 0.00005 (Q of 20k) and slightly below. We tested a few of the Soviet Mica 35mm Square Tub Caps for a couple members, some of these had D of 0.00006~0.00009 (Q of 11 to 17k)Anyway, Q and D should be viewed as somewhat relative numbers, more for comparing than absolute accurate, whereas as C or Z should be what's of more concern. For the design work we've done this was/is the case!!Edit: Here's the TH2830 Manual, see 6.1.17 pg 62.https://www.tonghui.com.cn/upload/UploadAction2/20191126092917_886.pdfand the IM3536 Manual, see section 10, pg 199, section 10.6 starting at pg 215 as you can see here the accuracy assessment of various parameters is quite involved!! Note the component measurement range on pg 224.https://www.hioki.com/download/29998Best

author: joeqsmith
author_rank: Super Contributor
timestamp: October 15, 2025, 01:56:10 am
content: Data for my second attempt to measure that 1.5uF PP cap. At least the majority are positive and 10kHz is actually close. Everything else is a bust.I can certainly understand why this is not a widely used method, but I can't understand why anyone would suggest using it.

author: gf
author_rank: Super Contributor
timestamp: October 15, 2025, 03:18:58 pm
content: Quote from: joeqsmith on October 15, 2025, 01:56:10 amWhich quantities do you actually want to measure and what levels of accuracy do you wish to achieve for each of them? Can you quantify?

author: joeqsmith
author_rank: Super Contributor
timestamp: October 15, 2025, 03:21:31 pm
content: Quote from: gf on October 15, 2025, 03:18:58 pmIn the context of this thread, to reproduce what G0HZU has claimed.