ESR meters and electrolytic capacitors

Talking about electrolytic capacitors and their failure modes, their impedance - equivalent series resistance (ESR) and equivalent series inductance (ESL), comparing them to other types of capacitors (tantalum, film, ceramic). Showing how to use ESR meters (capacitor testers), how do they work and what's inside. Including the schematic of a simple DIY capacitor ESR meter I've built 20 years ago: danyk.cz/esr_e...
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[@airmann90]

Leakage resistance is another important test, especially with smaller capacitors like film, ceramic and mica etc etc. It Tests the parallel resistance. Leaky caps can show a higher capacitance on a multimeter cap tester as its timing the time to charge to determine capacitance. A leaky cap will allow DC to pass when you really don't want it to!

[@DiodeGoneWild]

Yes, a leakage current tester is also a useful tool, but it's for another video ;)

[@airmann90]

@@DiodeGoneWild awesome! Looking forward to it.

[@radiotvrepair1059]

@@DiodeGoneWild thank you for making a video on the leakage current of capacitors.

[@michvod]

​@@DiodeGoneWild Cool, would love to see it. When I started repairing old gear, I didn't have anything capable of measuring leakage, but I did have a DMM that also measured capacitance. The strange thing was that the capacitance of old capacitors was about 30%-100% more than the value marked on them. Also the capacitance seemed to get higher when the capacitors got warm. Anyway, I discovered that you can measure leakage easily just by utilising a tube radio and its B+ (anode) voltage or any other voltage source with that sort of voltage. I connected one leg of the capacitor to the anode voltage rail and the other leg to the + probe of the DMM, and the - probe to the ground. On the bad capacitors the voltage didn't drop to zero, but stayed at various voltages as the DMM and its internal 10M impedance and the leaky capacitor created a voltage divider. Good capacitors went to 0V and stayed there

[@radiotvrepair1059]

@@michvod we can measure the resistance leakage of capacitors using an insulation tester and deduce the leakage current.

[@PeterMilanovski]

Another excellent video, when it comes to capacitors, I tend to look for capacitors with leakage problems as opposed to high ESR. I believe that capacitors with high leakage current tends to destroy other components around them... Usually capacitors with high leakage current tend to show higher capacity as if it's getting better with age but this is far from the truth.... I have seen other people who have KZbin repair channels that only check ESR which gives a good result but it's capacity has gone up over the rated value and I just know that it's leaking current and it's bad but when I mention it in their comments section, they disagree and get upset... I mean it's simple, what would a capacitor with high ESR do in a power supply and think now what a capacitor with high leakage current in the same situation do? High ESR will increase ripple and noise, high leakage current will cause the transformer to run hot or even burn out! So for me, leakage current (V Loss) from capacitors is far more important than ESR....

[@airmann90]

Great video. Nicely explains the traps that can fool someone new to reactive components.

[@randydicotti3975]

Thank you! Always find something helpful or useful at your channel. Glad to see your kitty is doing fine as well.

[@marka1986]

Designed and built my own ESR meter with mostly widely available parts from scraps. Mostly non critical transistors. I also had the input circuit so it wouldn't get zapped by input voltage. That made it handy to check the internal resistance of small gel cell batteries. Another good ESR meter to look up is LM324 ESR Meter. The meter he has with the 555 timer is also good and can be built quickly

[@EJEuth]

Great graphic explanation of the RLC series impedance

[@RoGameReview]

what a talantaded man, greeting from Romania 👋

[@hullinstruments]

Thank goodness! I’ve been hoping you would do more troubleshooting, repair, and test equipment related videos

[@I967]

Very nice. I might just build your simple ESR meter. Thank you for the video!

[@mrnmrn1]

I would suggest the Ludens ESR meter. It needs a transformer, but works great. I've been using it since 2009.

[@SuperBrainAK]

Super cool DiY version. It is awesome to keep around your original designs and things you made. I have a DE-5000 LCR meter which uses 4-wire connections to the leads of the device under test. That way it is able to fully zero out the leads and if you have the proper clips (it doesnt come with them so you have to make your own) it will zero out the resistance of the actual contact to the leads of the device.

[@overbuiltautomotive1299]

best ESR meter video ever

[@lorenzorentniop717]

I build your esr meter works great!

[@ThePetaaaaa]

Quite interesting video, especially the excursion with the graphic impedances!

[@hullinstruments]

I love your videos and I’ve watched some of them dozens of times. your cat is one of the highlights! He is so cute with his little smooshed face. It looks like he kept running into the wall or something. But A very handsome little fella

[@clems6989]

Excellent video! And exactly what I was looking for. THANK YOU !

[@saarike]

Simply excellent!!! Thanks a lot for interesting vid. 🧡

[@grzegorzpaczewski8529]

can't wait for a radio :D i think that repairs are the most interesting topics. Thanks for another useful and interesting video! I'm learning electronics myself and people like You providing me tons of knowledge that i can use for repairs and interesting projects (which are working about 10% of the time :D)

[@beatrute2677]

Awesome vid man, learnt a lot from this one, thanks.

[@CathySiegert]

Electrolytic capacitors can be lower than 1uF. In tapedecks and amplifiers, there are electrolytic caps with 0,1uF 50V or 0,22uF 50V installed. Mostly in Dolby B/C circuits.

[@DiodeGoneWild]

Yes, there are exceptions. I have also seen them, almost always open circuit.

[@longrunner258]

​@@DiodeGoneWild I have a Technics SU-Z780 amplifier with two 0.1μF (all made by Matsushita/Panasonic). Even they still measure fine, but I'd replace with MKT if they did fail (would be quite seamless given the lead forming to 5mm pitch). On a related note, many manufacturers are discontinuing 4mm diameter (and 5mm/7mm tall generally) electrolytics, so if you plan to recap devices which won't accept anything larger (and can't substitute ceramic or whatever), better stock up while they're still available.

[@mrnmrn1]

​@@longrunner258 Which manufacturers will stop making them and when? Any idea why they do so? In most cases, you can substitute these small caps with SMD electrolytics: straighten the leads, remove the black plastic plate, and you have a through hole capacitor with rather short and flat leads, but in many cases it is long enough to solder it in place of a miniature through-hole cap.

[@t1d100]

Good information. I learned some new things. Thank you.

[@domtom128]

A bit dodgy design ;) But seems to be decently accurate at least. 14:37 the first IC is LMV824 quad 5-MHz opamp. I can't read the marking on U4, but it's probably a Chinese ASIC, so it most likely wouldn't be of much help.

[@The_Hanter]

Taky jsem si několik let zpátky vyrobil ESR meter podle tvé schémy a úpřimně pokud si pamatuji, tak najít ty zprávné hodnoty odporů do toho byl celkem boj, jelikož hodnoty ze schémy nefungovali moc dobře 😄 Ale nakonec se povedlo a dobře posloužil 🙂

[@bluerizlagirl]

The absolute worst capacitor to fail is the one across the emitter resistor in a preamplifier. If it goes high-ESR, or open-circuit altogether, then the amplifier will have a much lower gain because without the action of this capacitor, the voltage drop across the emitter resistance goes up with the collector current and now this is fighting with the base voltage. But, of course, all the DC conditions will appear perfect when measuring with a multimeter! By the way, brilliant use of vectors!

[@arkadiuszgremza5963]

First chip is LMV824 - 4 op amps; second is probably Microchip PIC18F24K20 microcontroller, although markings don't exactly match datasheet

[@michaelseitz8938]

How does this ESR meter compare to your "transistor testers"? I have one of these "multi testers" and plan to install banana plug sockets. Hopefully it can test resistors in circuit too. Also, thanks for pointing out how to screw self tapping screws back into plastic threads! I see so many (professional) youtubers not do this, and it makes me cry in pain every single time 😢😭😂😁

[@vaclavtrpisovsky]

Interesting. I would not suggest in-circuit testing with a transistor tester, though. Also, it probably applies the voltage at reverse polarity as well so it might not be a good idea to use with e-caps at all.

[@michaelseitz8938]

@@vaclavtrpisovsky Are you afraid the tester would destroy something else in the circuit? These "multi-function testers" have the capability to test (polarised/non-polarised) capacitors (capacity and ESR).

[@DiodeGoneWild]

The transistor tester can only accurately measure higher ESR. On top of it, it can't measure capacitors in circuit. So it can't really replace a proper ESR meter.

[@perhansson6718]

​@@DiodeGoneWild It can measure low ESR but you need to calibrate it first as I commented in your previous video: "Transistor tester comparison, test and box assembly" It can also perform in-circuit measurements if you use the function "C+ESR@TP1:3" from the menu, because then the testing voltage is only 300mV so it will not bias most semiconductors.

[@johncoops6897]

Transistor tester doesn't use 100kHz and the precision is very low. They definitely work OK for comparison testing, but the calculated ESR is nowhere near as accurate as the MESR or Bob Parker designs.

[@ScrewBot]

Amazing DIY ESR meter. You are an inspiration for newbies like me. Sir i have tried to go through the schematics of your ESR meter and i am failing to read it. Can you further explain it? Or have the components build on a bread board so that many of us can see what components and try to build one for ourselves. I am sure many of us are wanting to build this amazing meter. Can you please help me with it? Thank you.

[@Speeder84XL]

Nice video! ESR of the output capacitor (usually electrolytic) is also an important factor for switching voltage converters, since it's a source of ripple voltage. Sometimes it helps more to lower ESR (by for example change to a better capacitor or put many in parallell) than increase the capacitance when it comes to minimize ripple (especially on the output of example boost converters or flybacks, where the capacitor alternates between charge and discharge)

[@video99couk]

The Peak Electronics ESR meters have a four-wire connection to the croc clips. I have the older ESR60 model to which I've added a remote control footswitch.

[@rfdave3980]

I like your Cat. You made me chuckle, "Bloody hell" Yeah colour of wires backwards. I saw a movie were the guy made a bomb and on purpose wired it backwards. Thanks for the Chuckle.

[@michaelfisher9671]

Given how useful it is to be able to test ESR, why don’t multimeters have an ESR function?

[@DiodeGoneWild]

that's a good question :) maybe they want to sell more devices.

[@michaelfisher9671]

@@DiodeGoneWild so there is no obvious technical barrier?

[@JandeVu]

I have it one MESR-100. It's good device.

[@tactileslut]

Tantalums have a particularly exciting failure mode if dropped in where the engineer specified electrolytic. :)

[@westelaudio943]

I think it's very debatable that Electrolytics are the most unreliable components. It depends on the age and purpose of the curcuit as well as weather conditions. Older electrolytics (pre-miniature) generally were more reliable, and you had other components which were far worse (like paper-wax capacitors, early small-signal Ge transistors) which are frequently or, in the former case, practically almost defective, however production of these components ceased in the late 1960s for the most part so it's hard to tell how long their useful lufe actually was... In overengineered modern electronics, you often get overheating induced IC bond wire failure (especially on TI chips) or other IC defects, more often than bad caps if the caps are of decent quality. In a SMPS you are right, they are hard on caps and use crappy miniature ones of course, often of the cheaper kind, and failure can sometimes lead to cascading as well...

[@rkan2]

Yeah, it is not necessarily the most unreliable component, but I think it could still be said that they are the most replaced component when fixing something worth fixing. Often when fixing something that is not worth fixing has gotten such a zap that it wasn't really the Electrolytics fault anyway - meaning that ICs and other components failed because of something and not just on their own like electrolytics still often do.

[@rilosvideos877]

Excellent - like always! You really bring it to the point in the first sentences. And, very important, you point out that the best measurement equipment is useless if you use it without brain! ;-) The tool won't do the thinking - you have to know what you want to measure and what effects bias the measurement! To be honest, i wasn't aware of all the effects - so thank you for sharing your expertise! Would be interesting to check its accuracy against the Multi-component tester :-)

[@tj051976]

Your stuff is all good, I always learn something by watching your videos !! Does your cat have a name ?

[@Michael-hw5qq]

I have an old set of logitech z5500 which developed a high pitch noise. I replaced the 16v 1000uF capacitor in the control pod and it went away. The capacitors in it are 14 years old and exposed to heat 😕 while in operation. The subwoofer amp has heatsinks thankfully.

[@TechStuff365]

Very useful thanks.

Que ótima análise!

[@mrmeval]

The penultimate capacitor testing device was a Sencore LC103 that can test leakage to 1000 volts ratings. Long obsolete. It was around 5k in the 90s.

[@jstro-hobbytech]

So you built that esr meter in your teens? Haha wild

[@DiodeGoneWild]

yes :) as a poor kid, I couldn't buy anything fancy, I had to build it.

[@jstro-hobbytech]

@@DiodeGoneWild I know exactly what you mean

[@ArifKhan-bp9zx]

@@DiodeGoneWild Wow.. are you a professor in collage??

[@AjudaTecnica]

Teacher, please activate the subtitles for this video, I have a device like this one and this video can help me to know him better. I'm looking forward to the subtitles. Thanks.

[@robinvince616]

I would have thought it possible to use a more complex design of meter which measures the voltage developed across the capacitor at TWO suitably spaced test frequencies. The change in voltage would enable the unit to calculate both the value of the capacitor and its ESR. Or with more than two frequencies, it should be possible to increase the reading accuracy over a wider range of capacitance values.

[@hullinstruments]

What about those new fangled multi-layer ceramic capacitors? I mean I know they're not going to go up to a few thousand microfarads or anything like that... But from what I've heard they are well on their way to replacing 70 or 80% of electrolytics. That could be total bullcrap though and I would love to hear your opinion. I haven't used them very often or done enough research to be an authority on the matter. And your input is always spot on and I'm constantly surprised of things I learn even after doing professional metrology repairs and servicing professionally for nearly a decade

[@tonyweavers4292]

I tried longer (good quality) test leads but they would not zero. Can this be achieved?

[@mikejones-vd3fg]

Very cool, nice to see what a capacitor tester actually does and how they fail. As and as soon as you said "sends a high frequencey signal and measure the voltage differance" i thought this would be so easy to do with an arduino, maybe a diy esr tester? Anyway I just got an arduino microcontroller and starting to see its power and versatiilty but also its huge overhead and maybe impracticality to use as a permanent solution, so its nice to see one done with a 555 timer. Its only missing a digital screen and you could sell that for 50 cents on ali expresss per unit and become a zillionaire. Or just put in one of the newest $5 microcontroller and sell the unit for $1000 as the best ESR tester on the block.

[@perhansson6718]

Look up the "transistor tester" or "component tester" also featured here on the channel in the most recent videos, it uses an Atmega to do allot of crazy stuff, best part is the firmware is open source so you can play with it to your hearts content: unfortunately all Chinese eBay sellers mention nothing about that and just "steal" the code and sell it as their own, without even a link to the original source...

[@user-ry8ew2ee6r]

Doesn't the protection diodes affect the esr reading??🤔🤔

[@arnislacis9064]

Recently my computer stoped working. The problem was in Powersupply, bolging capacitors on +5V rail. Powersupply is 15 years old, i replaced capacitors, now my computer is working again.

[@zx8401ztv]

Perhaps you can find some 50mm long solid 3 mm thick copper wire and solder plugs on to it, then cut it in the middle and tin the ends to solder the component to. Short thick wire = low d.c resistance and low inductance. I did the same for my multimeter reading low value resistors. Probe leads are shit, unless you are using car jumper cables ha ha :-D

[@jkobain]

So the ESR means basically «bare» resistance of the electrodes and plates - how slow they pass current and distribute charges, right?

[@johncoops6897]

Ummmm... kind of, but not really. It's the amount of resistance that appears to be in series with the capacitor. That resistance causes a reduction in the amount of current that can be drawn (filtered) by the capacitor. Under zero load, the resistance doesn't really matter. When the capacitor is required to "work hard", the resistance causes a loss of effectiveness, as it wastes power and converts it to heat. It's basically the same as Internal Resistance of a battery. You can use a Ni-MH battery with high internal resistance inside a clock or solar LED light and there will be no problem. However if you use that same battery for a toy with a motor then the voltage will sag really badly under load. The battery won't "work well" at high current.

[@higamitakaro]

Can you comment how Mr.Carlson's device works?

[@gacherumburu9958]

How does this compare with the transistor tester reviewed earlier on this channel?

[@DiodeGoneWild]

This measures the ESR better than the transistor testers, expecially for low ESR values.

[@change_your_oil_regularly4287]

Had two large capacitors 10,000uf 63v fail short circuit in one of my amps and overheated the transformer melting the epoxy on the secondary windings. My luck.

[@widyahong]

@DiodeGoneWild will esr meter damage the polarized capacitor? because its send ac voltage? (backward voltage) especially to low voltage polarized capacitor?

[@user-ry8ew2ee6r]

No. The voltage is rectified by a Germanium diode.

[@Evgen-Evgen-Evgen]

Hardly understand half of it, but very interesting))

[@fumthings]

they ought to design equipment with the electrolytic caps on a daughter board that can be unplugged for replacement...

[@SHREDTILLDEAD]

I am not good at math, and have some vintage tube amps I am doing my own servicing on. I can determine that my filter caps need replaced based on them reading the "worst case values" on a chart based at the lower capacitance and voltage, but if I were to want to fill in the blanks for the values that typically are not listed on the charts should I just determine the percentage increase of worst case value and voltage and guess it that way? In summary I have a 330uf filter cap at 300vdc typically not listed on those charts. Thinking maybe just determine difference between available values ? Then solve for 300v for increase from 250?

[@DiodeGoneWild]

If the table doesn't show 300V rating, just use the ESR value somewhere between 250V and 350V (or 400V). ESR is no exact math. Just ballpark numbers. There's dozens of ESR tables on the internet and each shows different ESR values anyway :).

[@minininja5891]

Hello, could someone please explain to me how the DIY version works, i have visited the website but it didnt really answer my question. So how does it work, i dont understand the diode across the resistor and the meter and how come the voltage changes in a parallel circuit , i thought it would stay the same, or atleast thats what im used to assume. How come the other parallel components after the measured Capacitor dont show on the meter , is that compensated by the resistor ? Im sorry for probably a very stupid question but i cant crack it :/

[@EwaldBurger]

@miniminja5892 a late response, but anyway: D2 is there to protect the meter. Assume there is no test capacitor connected. In that case the relatively high voltage output pulses of the 555 (minus voltage drop over D1) would reach the series connection of R2 and the meter. Diode D2 clamps that voltage to about 0.7V. The rest of the voltage drops over R1. When a test capacitor is connected, depending on its ESR, the voltage pulses that reach the anode of D1 would be higher (high ESR) or lower (low ESR). These pulses are rectified bij D1 and flattened and averaged by the capacitor after D1 to form a stable DC voltage that can be indicated by the meter. Hope this helps.

[@dxdxdxxd]

100khz isnt really good for electrolytic caps, the use most of the time with like 50 or 100hz max, this tester is perfect for film or ceramic cap. Better lcr meters include measuring frequency change option. Nice video!

[@filipeoliveira4767]

In modern PSUs they are used with higher frequencies

[@mrnmrn1]

100kHz is the industry standard test frequency for electrolytics, too. Open the datasheet of any modern electrolytic cap (especially low-ESR series), and you will find that the test frequency the manufacturer uses is 100kHz.

[@jesuschal3802]

What about the ESR meter on the transistor tester? How reliable is it?

[@mrnmrn1]

Not too bad, but you can't use it in-circuit.

[@DiodeGoneWild]

It won't work in circuit and it can only measure higher ESR values.

[@nicushorul2007]

Cat at 15:24 ;)

[@thomass7877]

Is the capacitor resistance formula shown a measure for ESR .. that is, does it replace the tables we can find on the internet. For example if the formula says 1 ohm and the ESR meter shows the same 1 ohm .. do we consider that a good capacitor? Please reply from anyone ...

[@perhansson6718]

It depends on the test frequency: for "general purpose" caps the test frequency in the datasheets is 100/120Hz (line frequency times two) and for low ESR capacitors the test frequency is usually 100kHz (it must be mentioned in the datasheet) the tester needs to use the same frequency, only some more expensive hand-held ESR meters like Agilent U1733C and DER DE-5000 are. In the real world though capacitors for low frequency rarely fail so these cheaper testers with only one frequency are usually "good enough" for what we need to fix a board...

[@thomass7877]

@@perhansson6718 Thank you very much for the answer. I am an old hobbyist ... so any help is welcome .. I have a cheap BSIDE ESR meter, which I believe works at 10 khz ..

[@radiotvrepair1059]

is this ESR meter you built we can measure the capacitors on the motherboard??

[@DiodeGoneWild]

yes ;)

[@mrnmrn1]

@@DiodeGoneWild Usually it's difficult because motherboards have many-many capacitors in parallel. To test them, you need to desolder them. Parallel capacitors is an example when even an in-circuit tester is not reliable. Motherboards can have many dozens of high capacitance multi-layer caramic capacitors on each supply rail, and the sum of those represents a very low ESR. I bought a Chinese ESR meter which is the clone of a late '90s Elektor Magazine ESR meter. It uses a synchronous rectifier to eliminate the impedance of the capacitor, it measures purely the ESR. It can measure the ESR of capacitors down to ~10nF! Some MLCC and film caps with such low capacitance can have suprisingly low ESR. This makes this meter unreliable for in-circuit use, because it will measure the small decoupling capacitors as well. So it's kinda too good to be useful :-) .

[@subhasishbhaduri2938]

Sir can you please suggest a good budget esr meter? Or can you please show how to make one?

[@andymouse]

He did at the end.

[@mikebond6328]

This video did both.

[@Conservator.]

It’s a bit over € 50 including 21% VAT and shipped to the Netherlands. What parts of such a meter will make it so expensive?

[@DiodeGoneWild]

It's not the parts that make it expensive. It's the maker or the seller having the balls to ask for that much money, and the buyers accepting to pay that.

[@Conservator.]

@@DiodeGoneWild Good to know! Thank you!

[@AmitabhAnkur]

Demand and supply.

[@r.franky8306]

Personally I like and i am really satisfied with Peak Atlas ESR 70. It's around 100 euro.

[@celsoneves2368]

Good!.

[@I_like_some_BG]

Thank i can repair my USB failure it was Huawei super charge 10 volt 4amp 40wats

[@id-iz2ds]

sir can the esr meter measure the ceramic smd capasitor ?

[@DiodeGoneWild]

I think ceramic capacitors don't develop high ESR.

[@r.franky8306]

For that you can use Peak Atlas LCR 40

[@attilarivera]

👏👏👏👏👏👏👏👏

[@robstorms]

thanks!@!

[@Tigrou7777]

6:47 isn't the measure skewed by holding it like this ?

[@DiodeGoneWild]

In this case it's not, because the impedance of my fingers is several orders of magnitude higher than the impedance of the capacitor.

[@electronicengineer]

@@DiodeGoneWild Hi Dany, I just want to tell you that your English is exceptionally good! Excellent, as a matter of fact. Thank you for making your great videos. Fred

[@mrnmrn1]

@@DiodeGoneWild But it can still screw up the measurements with small caps like this, because your fingers warm up the capacitor, which lowers the ESR. When I trubleshoot a marginal board I used to put it into the fridge for a few ten minutes, and test the capacitors while they are cold.

[@volleswerkfullorganpower249]

👍

[@anoimo9013]

One very crude poor man's method for checking high capacitance capacitors with the multimeter is to check resistance on high resistance scale. the capacitor will charge with the internal battery of the multimeter and show briefly low resistance, then progressively higher. if the capacitor has low capacity either by design or damage, it will show very high resistance right away. having a good capacitor to compare is really handy. Naturally you have to discharge the capacitor between measurements

[@petehiggins33]

Try twisting the leads tightly together.

[@nowheremanjk8624]

Kot w porę otrzegł ;-}

[@debmalya6144]

Lmv824

[@qzorn4440]

seems like the world is long over due for cheap long life electrolytic capacitors 🙄 some of the super battery chemicals may lend a hand on new cap ideas 😎 thanks a lot o my if all that is going on just on the test bench who knows what absolutes are happening in the real circuit? old cartoon 🐱 top kat

[@milovanmitrovic-miks6174]

zdravo ja sam milovan iz srbije,potrebna ni je pomoc oko esr testera,napravio sam ga ali nesto neradi,tester je kao onaj tvoj stari...

[@farzinfirozian2722]

There is some thing ronge this time with the sound.

[@tonysheerness2427]

A lot of trouble for something that is going to fail just replace them all with new ones and skip the testing.

[@westelaudio943]

Just to find out that in the end it still doesn't work and the fault is actually a blown winding on a transformer... Ouch!

[@tonysheerness2427]

@@westelaudio943 At least the caps are OK. and will last for sometime.

[@westelaudio943]

@@tonysheerness2427 Yeah but when unobtainable components are blown, what's the point really...

[@gitawrongtranslation-youtu9701]

Extra money 😒

[@AmigaWolf]

I love your video's, and i hope you also test the BSIDE ESR02PRO (Transistor SMD Components Tester Diode Triode Capacitance Inductance Meter), it is very accurate, also do not cost much, and i have tested the ohms with a Elenco RS-500 and a calibrated Fluke 179 True-RMS Digital Multimeter, and the BSIDE ESR02PRO is also calibrated great, it gave almost all the same numbers as my calibrated Fluke 179. It has a ESR Value Of Electronic Capacitor unit paper on the back, so you know the right ohms of what a good cap should be, i made one and printed one on a A4 paper, and put it in the box of the BSIDE ESR02PRO, so you do not have toturn over the BSIDE ESR02PRO to see if the cap has the right ohms value.