ESR meters

One way to test electrolytic capacitors is to measure their capacitance. It does not tell the whole story of capacitor condition. Another usually more useful way to measure electrolytic capacitor condition is to use an ESR meter.

EEVblog #365 – ESR Meter Bad Cap Monitor Repair video gives you tips how to use ESR meter to find bad electrolytic capacitors:

An Equivalent Series Resistance Meter article has a good plan for DIY ESR meter. I have built it and found it well working. Building an ESR meter for Testing Electrolytic Capacitors has a nice table of ESR values you could expect from different capacitors and you can find another table here.

Here are links to some other ESR meter plans and information:

Wikipedia ESR meter page

The Most Useful Tool for Identifying Bad Capacitors

ESR meter page

Building an ESR meter for Testing Electrolytic Capacitors

Capacitor ESR Tester

25 Comments

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  2. tomi says:

    Testing caps with a DIY ESR meter
    http://hackaday.com/2013/03/16/testing-caps-with-a-diy-esr-meter/

    The entire circuit is built on stripboard, and if you’re lucky enough to find the right parts in your random parts bin, you should be able to build this ESR meter with components just laying around.

    Building an ESR Meter
    Building a simple ESR meter for troubleshooting electrolytic capacitors.
    http://paulorenato.com/joomla/index.php?option=com_content&view=article&id=94:building-an-esr-meter&catid=4:projects&Itemid=4

    Reply
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  7. Tomi Engdahl says:

    #135: Measure Capacitor ESR with an Oscilloscope and Function Generator
    https://www.youtube.com/watch?v=115erzCCxgE

    This video discusses how to measure the ESR (equivalent series resistance) of a capacitor using an oscilloscope and function generator. All of the capacitors tested in this video were 220uF electrolytic caps. In reality, the resistance in the plates of a dried out electrolytic capacitor can’t be modeled as a simple series resistor, but for the purposes of identifying good from bad, this simplification works fine.

    Reply
  8. Tomi Engdahl says:

    Getting a Handle on ESR with a Couple of DIY Meters
    http://hackaday.com/2016/11/14/getting-a-handle-on-esr-with-a-couple-of-diy-meters/

    Got a bunch of questionable electrolytic caps sitting in your junk bin? Looking to recap a vintage radio chassis? Then you might need to measure the equivalent series resistance of the capacitors, in which case this simple five-transistor ESR meter might come in handy.

    Even if you have no need for an ESR meter, [W2AEW]’s video below is a solid introduction to how ESR is determined. The circuit itself comes from EEVBlog forum user [Jay-Diddy_B] and is about as simple as such a circuit can get.

    #247: Circuit Fun: 5 Transistor ESR Meter circuit by EEVBlog user Jay_Diddy_B
    https://www.youtube.com/watch?v=3fiUZZlveS0

    Reply
  9. Tomi Engdahl says:

    Don’t let ESR waste power and cook capacitors
    https://www.edn.com/electronics-blogs/power-points/4460700/Don-t-let-ESR-waste-power-and-cook-capacitors?utm_source=Aspencore&utm_medium=EDN&utm_campaign=social

    There’s an important real-world aspect to the ideal capacitor, called its equivalent series resistance (ESR), which quantifies the capacitor’s effective resistance RS to RF currents.

    This ESR actually has multiple constituent elements, including the part contributed by the electrodes and terminal leads, as well as that due to the dielectric, plate material, electrolytic solution, all as measured at a particular frequency. If you look at ESR in terms of the actual series resistance, the leakage resistance, and the dielectric loss, ESR goes from being just a resistor in series with an ideal capacitor to something more complicated

    Why should we worry about ESR? For basic DC-only blocking circuits, ESR may have little impact. However, when you are designing a switching power supply or an RF circuit, ESR obviously affects your modeling, and real-world performance of the circuit.

    Reply
  10. Tomi Engdahl says:

    #135: Measure Capacitor ESR with an Oscilloscope and Function Generator
    https://www.youtube.com/watch?v=115erzCCxgE

    Reply
  11. Tomi Engdahl says:

    Besides ESR you need sometimes to measure also capacitor leakage:

    Capacitor leakage tester design & build
    https://www.youtube.com/watch?v=0pySErvzUIY
    https://www.youtube.com/watch?v=cW9hHjOxmQw
    https://www.youtube.com/watch?v=NBUiaw18eOU
    https://www.youtube.com/watch?v=X4B79BYIlbY

    Invention Release! Carlson LV Capacitor Leakage Tester.
    https://www.youtube.com/watch?v=LhovRIM5xAo

    Reply
  12. Tomi Engdahl says:

    #135: Measure Capacitor ESR with an Oscilloscope and Function Generator
    https://www.youtube.com/watch?v=115erzCCxgE

    This video discusses how to measure the ESR (equivalent series resistance) of a capacitor using an oscilloscope and function generator. All of the capacitors tested in this video were 220uF electrolytic caps. In reality, the resistance in the plates of a dried out electrolytic capacitor can’t be modeled as a simple series resistor, but for the purposes of identifying good from bad, this simplification works fine. In the video, I show the ESR meter that I made in 2006. The video for that is here:
    #5: My ESR Meter project from 2006
    https://www.youtube.com/watch?v=bmYAgat-sOQ

    This video shows the design and use of an ESR meter that I built in 2006. I recently used this meter to find some bad electrolytic caps in an LCD monitor I’m working on, and thought it would be a cool project to share. Here is a PDF scan of the schematic:
    https://www.qsl.net/w/w2aew//youtube/W2AEW_ESRmeter.pdf

    Reply
  13. Tomi Engdahl says:

    3 Ways to Check Capacitors in Circuit with Meters & Testers
    https://www.youtube.com/watch?v=qDABYKoVO4Q

    Learn How to check bad Capacitors in circuit boards with ESR and Fluke multimeter, ESR meter reading is ohms and Fluke capacitor reads microfarads uf mf of a cap, see below for “capacitor meters”

    Reply
  14. Tomi Engdahl says:

    Acceptable Vloss in capacitor.
    https://www.antiqueradios.com/forums/viewtopic.php?f=6&t=310808

    I have recently purchased a great little tool to help test components with. It seems to work great and automatically identifies what component you are testing and it’s values. (Probably old news to most but I’m like a kid in a candy store with it) Anyway, with regard to caps, what is an acceptable voltage loss percentage? I’m working through this old northern electric 626 and will not replace the caps if they are testing good. I realize they may act differently in circuit and functioning but for now I’ll just pop in what’s way out of whack. Thanks!

    Any voltage loss % does mean the old capacitor is drying out. Does not get better and gets worse over time. Best to replace all old capacitors at the same time. Makes a dependable radio.

    Unless your tester can test capacitors at their rated voltage, it won’t find the bad capacitors in your radio. The general rule is that all the paper capacitors and almost all the electrolytics are bad. If you can’t test them with high voltage applied, just replace all of them.

    Paper [& electros] – particularly the higher voltage types – will [almost] always show some Vloss though, regardless of their state. You can probably figure on a couple of % or more being pretty standard for paper & electros (if you even bother to measure the latter!).

    I wouldn’t be surprised if old papers are up around 5%~10% or so simply due to materials & construction, not age or service-related deterioration. It’s also something of a pointless test in many cases, since (amongst other reasons) it doesn’t scale linearly with applied voltage – a cap that tests with a 1V drop @ the 3V supplied by a simple tester will show 30% Vloss, but the same cap might only drop 4V @ its rated 400V i.e. 1% Vloss and be perfectly within specs for its type.

    Vloss is the dissipation factor readout in these meters. 9% is D=0.09. Word is those testers use a 1 kHz test signal.

    Those yellow axial caps that people use sometimes have a dissipation factor of <0.01, or 1% at 1 kHz.

    A random high-end Kemet cap has a 0.04% dissipation factor. That'd be D=0.0004.

    In general, you should replace that style of cap straight away as they're so far past their working lifetime even if you randomly happen to find one that "works" it very quickly will stop doing so…but that is a fun tester and is pretty useful in a lot of situations!

    Reply
  15. Tomi Engdahl says:

    Capacitor voltage loss (Vloss)
    https://www.buizenradioclub.nl/media/kunena/attachments/1089/CapacitorvoltagelossVloss.pdf

    Additionally a new parameter is output for capacitors with more than 5000 pF and low
    quality factor. This parameter is the voltage loss (Vloss) immediately after a load pulse.
    Some older paper capacitors make problems to get the right capacity. The error can be
    more than 100%. Also other instruments have problems to measure the right capacity for
    that capacitors. For type of capacitor a voltage loss of more than 10% is measured, so the
    Tester gives you a warning hint with the Vloss.

    VLOSS = Initial capacitor voltage loss due to the energy required to complete the
    switchover operation

    Capacitor voltage loss (Vloss)
    Additionally a new parameter is output for capacitors with more than 5000 pF and low
    quality factor. This parameter is the voltage loss (Vloss) immediately after a load pulse.
    Some older paper capacitors make problems to get the right capacity. The error can be
    more than 100%. Also other instruments have problems to measure the right capacity for
    that capacitors. For type of capacitor a voltage loss of more than 10% is measured, so the
    Tester gives you a warning hint with the Vloss.
    VLOSS = Initial capacitor voltage loss due to the energy required to complete the
    switchover operation (see Figure 4).
    Voltage loss after a load pulse, Vloss 1
    [ With the measurement of capacitors with big capacity values the voltage loss after the
    loading is analysed. The reached load voltage is lost with electrolytic capacitors after a
    short periode. This voltage loss can be caused by a parallel connected resistor. But I
    assume, that this voltage loss of electrolytic capacitors is caused by a internal load
    dispersion directly after the load pulse. By loading the capacitors with the 470 kohm
    resistor, as it is done for little capacity values, this dispersion is already done after
    switching o the current. No voltage loss is detectable for this case. But if you load the
    same capacitor with a short current pulse, you can also detect the voltage loss for
    capacitors with lower capacity. The same e ect with lower loss can also be noticed for
    ceramic type capacitors.
    I have noticed, that capacitors with more than some % voltage loss are suspect. Especially
    noticable with respect to the voltage loss are older paper type capacitors, which are for
    other measurement a problem too.

    The TransistorTester can only
    determine the voltage loss, if the measured capacity is more than 5000 pF.

    Reply
  16. Tomi Engdahl says:

    All You Need To Know About ESR METER To Fix Stuff. How To Use Test Capacitors Inductors Short Finder
    https://www.youtube.com/watch?v=bMUzTGnvrbU

    Here we take a look at the various and curious ways we can use an ESR Meter! Learn how to test and recognise bad capacitors, test and measure unknown inductors and even trace short circuit MOSFETS using an ESR meter

    CHAPTERS
    00:00:00 Intro
    00:00:47 What Is ESR
    00:05:06 Testing Capacitors
    00:10:34 How Does ESR Meter Work?
    00:12:00 Bad Capacitors (type 1)
    00:14:19 Bad Capacitors (type 2)
    00:16:56 Measuring Inductors
    00:30:39 Short Circuit Finding In VRM
    00:38:04 That’s Not A Knife!
    00:40:04 Conclusion

    Reply

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