Talk:Electrolytic capacitor

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Are tantalum electrolytic?[edit]

I might be wrong, but i believe tantalum caps are polarized, but not electrolytic. The original sulphuric acid filled tantalums would have been, however i understand from my 10 second search that the normal, current ones might not qualify. —Preceding unsigned comment added by 121.214.192.24 (talk) 08:48, 2 December 2010 (UTC)

Polarity in circuit[edit]

So in what direction should i put a electrolytic capacitor in my electric circuit? minus on plus? or minus on ground? thanks, --Abdull 16:15, 6 Dec 2004 (UTC)

The negative terminal goes to the more negative terminal.  :-) So if your power supply is +V and Ground, the negative terminal of the cap goes to ground. If your power supply were Ground and -V, then the negative terminal of the cap would go to -V. - Omegatron 02:52, Mar 21, 2005 (UTC)
http://www.piclist.com/images/www/hobby_elec/e_capa.htm - Please use this as citation for 'bursting' capacitors. --220.253.205.91 (talk) 07:56, 22 August 2010 (UTC)

Safety/tantalums[edit]

I don't think much of the extended discussion of safety precautions for handling electrolyte leaks. I think that's of questionable relevance and value. I'm also dubious about some of the factual information in that passage - I already removed one howler (about tantalum capacitors being military-only) which looks like the information may be about 20 years out of date, and I suspect other nearby statements may be incorrect also. I think at some point in the future I'll probably delete that stuff, or move it to some other page. Not sure where yet, which is why I haven't done so already.129.97.79.144 21:05, 2 Jun 2005 (UTC)

I think we should keep that kind of information, but if it is out of date it should be updated. - Omegatron 23:00, Jun 2, 2005 (UTC)

Breakdown voltage and capacitance[edit]

I don't think that high break down voltage implies high capacitance as this entry suggests. -RG Atlanta

Where does it say that? - Omegatron 02:17, Jun 12, 2005 (UTC)
"the thinness of this layer, along with its ability to withstand an electric field strength of the order of 109 volts per metre, is what produces the high capacitance." - it's only the thinness that makes high capacitance, not the ability to withstand high field strength -RG Atlanta

Polarity[edit]

This Page seriously needs an explanation of correctly connecting axial polarized capacitors. I have to look that up every time I work with Caps. I don't feel qualified to write it up or I would add it myself!! —Preceding unsigned comment added by 74.203.110.1 (talk) 17:00, 1 July 2010 (UTC)

I remember reading somewhere that electrolytic capacitors only acquire a polarity after they have been used. The testing after manufacturing supposedly gave the polarity for most capacitors. Is this true? There are "non-polar" capacitors with cases and capacitances that are similar to normal electrolytic capacitors for sale here: http://www.allelectronics.com/cgi-bin/category/140900/Non-Polar.html --Pyrochem 03:47, 21 September 2006 (UTC)

You may find this enlightening: http://yarchive.net/electr/electrolytic_caps.html Quote: Non-polar electrolytics are two conventional electrolytic capacitors in series with the cathodes connected together. In actual construction, they are composed of two pre-anodized aluminum foils wound together. --QEDquid 16:24, 22 September 2006 (UTC)


I'm pretty sure the polarity for the -)|- symbol is wrong. I think the flat side should be positive. 68.40.101.59 01:05, 14 January 2007 (UTC)

Degradation due to age[edit]

I think this page should include a note that, compared with other types of capacitors, electrolytic capacitors break down with age. There's sort of a statement to this effect, that a positive voltage must be maintained or the electrolytic will break down. But old electrolytics are the overwhelming cause of hum in old AV equipment, so a statement along these lines might be helpful to someone.

Rock it out. max

  • Yes, this is very true. The Polarity section of the article makes reference to the increased life of the capacitor when forward biased. I added additional information to the variants section, under the Aluminum, about electrolyte drying out / failing in the absence of a sufficient rejuvenating voltage. With regards to older AV equipment my experiences have been more to do with poor quality in the capacitor construction and excessive temperatures in use and storage. Treat old capacitors with respect, replace them with modern counterparts where ever possible. ADevNull 05:36, 11 April 2007 (UTC)

Inventer of electrolytic capacitor[edit]

"..electrolytic capacitor was invented in 1921 by Julius Edgar Lilienfeld ..." can this be true? There are numerous earlyer patents from Charles Pollak:

  • Charles Pollak: Improvements in or connected with Electrical Condensers. In Patent number: GB189601069 (1896)
  • Charles Pollak: Improvements in Electrolytical Condensers and Electric Current-directing Devices. In Patent number: GB189800933(1898)
  • Charles Pollak: Improvements in or connected with Electrolytical Condensers and Electric Current Directing Devices. In Patent number: GB189818956 (1898)

--141.30.240.194 09:46, 12 February 2007 (UTC)

    • Charles Pollak, German Patent 92564, 14. Jan. 1986, Flüssigkeits-Kondensator mit Aluminium-Elektroden

--Elcap (talk) 17:31, 27 December 2007 (UTC)

Tantalum capacitor edit[edit]

I just edited this out of the page (it was an extra copy at the end of the list of types), maybe someone can check and edit:

Tantalum: compact, low-voltage devices up to about 100 2000µF, these have a lower energy density and are more accurate than aluminum electrolytics. Compared to aluminum electrolytics, tantalum capacitors have very stable capacitance and little DC leakage, and very low impedance at low frequencies. However, unlike aluminum electrolytics, they are intolerant of voltage spikes and are destroyed (often exploding violently) if connected backwards or exposed to spikes above their voltage rating. Tantalum capacitors are also polarized because of their dissimilar electrodes. The cathode anode electrode is formed of sintered tantalum grains, with the dielectric electrochemically formed as a thin layer of oxide. The thin layer of oxide and high surface area of the porous sintered material gives this type a very high capacitance per unit volume. The anode cathode electrode is formed of a chemically deposited semi-conductive layer of manganese dioxide, which is then connected to an external wire lead. A development of this type replaces the manganese dioxide with a conductive plastic polymer (polypyrrole) that reduces internal resistance and eliminates a self-ignition failure[1

Yes, 2200uF tantalums and even larger ones exist (check digikey). But the general use of tantalums dont't go beyond several hundred uF.

81.215.13.145 07:52, 4 June 2007 (UTC)

Possible erroneous statement at the end of this article?[edit]

"However, unlike batteries, capacitor voltage is directly proportional to the total energy remaining" - the voltage is proportional to the square root of the remaing energy, isn't it? —Preceding unsigned comment added by 213.79.33.10 (talk) 23:55, 8 September 2007 (UTC)

Energy = 0.5 x capacitance-in-Farads x voltage-squared -69.87.199.150 13:10, 14 September 2007 (UTC)

I think it's using a more general sense, indicating that raising one will raise the other. Might be directly proportional, but not linearly proportional, if I get the idea right. KronesR (talk) 23:41, 7 March 2012 (UTC)

Polarity marking[edit]

"The correct polarity is indicated on the packaging by a stripe with minus signs and possibly arrowheads, denoting the adjacent terminal that should be more negative than the other."

This article is generally pretty well done, but this statement about polarity marking is greatly over-simplified, with no acknowledgement of a century of history and different capacitor packages. It is too bad the article does not have a picture of a typical unpainted metal can electrolytic capacitor from decades ago. I think polarity was usually marked with a dot of red paint. Did this mark positive? And current small drop caps are also polarity marked with a dot of color. But does this mark positive or negative?-69.87.199.150 13:10, 14 September 2007 (UTC)


--- I agree. See above about dire need for instructions on correct reading of polarity and why its important when using polar caps. —Preceding unsigned comment added by 74.203.110.1 (talk) 17:10, 1 July 2010 (UTC)

the cylindrical aluminium casing fell off[edit]

does this interfere with the functoning of the capacitor or the capacitor should be replaced? —Preceding unsigned comment added by 66.16.40.22 (talk) 14:06, 14 October 2007 (UTC)


Electrochemical double-layer capacitors (EDLCs), also known as supercapacitors or ultracapacitors[edit]

Electrochemical double-layer capacitors (EDLCs), also known as supercapacitors or ultracapacitors are NOT electrolytic capacitors. They have to be cancelled here. Please compare with the german article. --Elcap (talk) 08:54, 20 December 2007 (UTC)

NP caps error[edit]

"Essentially, a 10 microfarad AC capacitor behaves like two 20 microfarad DC capacitors in inverse series."

If one cap shorts during each half cycle, then to obtain a result of 10uF one would need to connect 2x 10uF back to back, not 20uF. —Preceding unsigned comment added by 86.4.152.167 (talk) 14:10, 6 October 2008 (UTC)

No, I think the article is correct as they are connected such that both are partially charged during the whole AC cycle. Han-Kwang (t) 14:13, 6 October 2008 (UTC)

What exactly does that mean? Why dont you descrbe what you mean step by step. —Preceding unsigned comment added by 86.4.152.167 (talk) 14:16, 6 October 2008 (UTC)

I'd rather ask: what do you mean when you say that one cap "shorts during each half-cycle". By the way, you can add ~~~~ to sign your posts. Han-Kwang (t) 06:11, 7 October 2008 (UTC)


OK then... when wrong polarity is applied, the insulating layer begins to conduct. Hence for each half cycle we have one working capacitor in series with a low impedance. Hence 2x 10uF 'lytics in series gives 10uF, not 5.

I can indeed sign my posts with tildas, but I don't think it would be very useful given that I'm not logged in. —Preceding unsigned comment added by 86.4.152.167 (talk) 16:12, 7 October 2008 (UTC)

Service life[edit]

IRL there are a vast number of capacitors in successful service at over 15 yrs old. 15 year life expectancy is not a real world figure. Caps can die with age, but in reality the great majority don't. Some are even still in service from the 1930s. —Preceding unsigned comment added by 86.4.152.167 (talkcontribs)

Apparently this number is an example. The given reference explains that capacitors are rated for a specific service life. If you can find a reference (data sheets, manufacturer catalog) with a service life, you can replace the number by a typical range of service lifes. Han-Kwang (t) 06:24, 7 October 2008 (UTC)

I think that would be missing the point. The point is that despite these oft quoted short ratings, a sizeable percentage of lytics from half a century ago and longer are still working fine. Otherwise readers are liable to imagine that after 15 or 20 years most lytics are dead - and this is far from the case.

Capacitance Change with misuse[edit]

I have heard and read that Electros will change their capacitance if used on a much lower voltage circuit them they were designed for. I.E; a 100 mF 400V unit will lose capacity on a 16 Volt circuit due to less electrolytic action. To restore such a cap, or, any old one that you have a doubt about; simply connect it to a current-limited (a few mA) voltage source of about 70% of its rated voltage overnight. It will work in a "pinch" or if it is a vintage or very expensive cap you don't wish to,or can't, simply replace (ARRL Handbook)Tintinteslacoil (talk) 13:43, 24 November 2008 (UTC)

self-contradiction[edit]

The section discussing tantalum capacitors seems to contradict itself:

Is it really true that tantalums simultaneously "have a lower energy density ... than aluminum electrolytics" and yet have "higher capacitance per unit volume" ? Is that "higher capacitance per unit volume" than aluminum electrolytic, or is that compared to the other kinds of capacitors in cell phones?

Rather than vaguely saying one is "higher" than another thing, would it be OK to print a typical value for each one? --68.0.124.33 (talk) 22:02, 16 October 2008 (UTC)

?[edit]

this sounds like a cross between a battery and capacitor its sounds weird that a capacitor would use a electrolyte where would you distinguish the difference between a battery and capacitor because this is made the same way as a battery?urName (talk) 08:05, 8 February 2011 (UTC)

OS-CON[edit]

Two things about it, more wording/formatting issues.

"These capacitors are stable in use between -55°C to practically 125°C in theory." "practically" and "in theory" don't go too well in the same sentence. Does it mean "close to 125 in theory" or that it could actually go as high?

The whole topic about OS-CON should go right after the Tantalum one. Seems there is a break, some text, then it goes to OS-CON. That "extra" part seems to belong to the Tantalum section. Should it be joined? — Preceding unsigned comment added by KronesR (talkcontribs) 22:07, 4 January 2012 (UTC)

Polarity: no reduction of oxyde layer[edit]

Most electrolytic capacitors are polarized and require one of the electrodes to be positive relative to the other; they may catastrophically fail if voltage is reversed. This is because a reverse-bias voltage above 1 to 1.5 V[4][5][6] will destroy the center layer of dielectric material via electrochemical reduction (see redox reactions). Following the loss of the dielectric material, the capacitor will short circuit, and with sufficient short circuit current, the electrolyte will rapidly heat up and either leak or cause the capacitor to burst, often in a spectacularly dramatic fashion.

This seems to be the general opinion, but I haven't seen a WP:RS confirming it. Both anode and cathode are made of aluminium. I know they say that the electrolyte is really the cathode, but that's when one only considers what happens at the anode oxide layer. In fact, apart from the larger surface and the thickness of the oxide layer, both anode and cathode are identical. The oxide non-oxide region forms a diode, with the thickness of the oxide layer determining the breakdown voltage. If correct voltage is applied, the diode at the anode junction will be reverse biased so no current will flow; at the cathode junction the diode is forward biased and conducts current. Applying an overvoltage, the anode junction will breakdown and current will flow through the capacitor.
If voltage is reversed anode and cathode switch places, so now the cathode junction is reverse biased. The main difference is the thin oxide layer that can only withstand a small voltage before breaking down.
In both cases, when the applied voltage is too high, current will flow. This has three effects: growth of the oxide film, gasses forming, and ohmic heating. Depending on the magnitude of the current, you get a capacitor with lower capacity, a swollen capacitor due to gas build-up, or a cap that blows because you're boiling the electrolyte.
See ref 6, or an application guide from a manufacturer. Main point is: there's no reduction of the oxide layer, at least not enough to have any effect. Ssscienccce (talk) 16:19, 2 September 2012 (UTC)
The “redox reactions” in the sentence: “…a reverse-bias voltage above 1 to 1.5 V will destroy the center (?) layer of dielectric material via electrochemical reduction (see redox reactions)” are wrong. Aluminum oxide goes in solution in acid or basic liquids. Reverse voltage can accelerate this whereby the oxide layer will be weakened. The layer gets thinner. If the voltage is high enough and the power behind is high enough (low ohmic) than after a while a breakdown occur (short circuit). It is a demolition of oxide layer thickness in an acid or basic solvent which lead to this behavior. --Elcap (talk) 09:47, 18 November 2013 (UTC)

The new rewrite versus the old[edit]

The new rewritten version has many grammatical flaws and basically removed everything from before. It would be nice to incorporate the old version from earlier this month into the new version, as both have their merits. — Preceding unsigned comment added by Theburn7 (talkcontribs) 11:57, 28 December 2014 (UTC)

Hi Theburn7, I have tried to use all correct informations from the old version, but sorry, there was wrote such a lot of balderdash, that I decided to write it new as an article summarize all excisting electrolytic capacitors. The old text only was focussed on Aluminum electrolytic capacitors, which now have an own article. However, you are right in citicize my English, sorry, I hope, some Wikis can help in bettering grammar and wording. --Elcap (talk) 14:57, 29 December 2014 (UTC)

Electrolytic capacitor – new article Dec. 2014[edit]

Hi Wikis, I have written a complete new article about electrolytic capacitors and replace the old one Dec. 14. Yesterday the user “Wtshymansky” delete the new article and restore the superior version. Everybody who wants to follow the discussion can have a look at the new article under User:Elcap/Electrolytic capacitor.

The reason I wrote a new article was the destroying of the article Capacitor plague in Feb. 2014. Trying to repair this article I saw, that the English Wiki had no article about Aluminum electrolytic capacitors. But to understand what happened with failing capacitors using a wrong electrolyte it was necessary to write an Al-e-cap article first. By the way I wrote an article about Niobium capacitors and add some paragraphs in the article Tantalum capacitors, all members of the great family of electrolytic capacitors. Remained the question of what happens with the old article “Electrolytic capacitors”?

This old article really is a conglomeration of superficial knowledge and wrong information. Let me give some examples:

The first sentence: - An electrolytic capacitor is a capacitor that uses an electrolyte (an ionic conducting liquid)…. This is incomplete, most Ta-e-caps use solid electrolytes. - ….uses an electrolyte (an ionic conducting liquid) as one of its plates to achieve a larger capacitance per unit volume…. is wrong, the thin dielectric layer coming from the anodic formation is the main reason for high CV. - They are widely used in power supplies…. is only valid for Al-e-caps, not for Ta-e-caps and Nb-e-caps - The rest of the introduction are preconceptions coming from outdated experiances.

In the part “History” the notice about Lilienfeld is wrong, sorry he was a genius but not for electrolytic capacitors. The remarks about “Mershon” are a very special information only for Americans.

The part “Types of electrolytic capacitors” is a collection of types, electrical parameters, antiquated values and wrong information. Starting with “Supercapacitor” not explaining that SCs are not e-caps down to OS-CON capacitors which are not available anymore with that mentioned solid electrolyte.

Going down the singe paragraphs I found a lot of antiquated, misplaced or wrong information in the old article so that I decide to write a new one to give precise information and to compare with tables and pictures the three different electrolytic capacitor types. This new article yesterday was replaced by the old one.

By the way, I have tried to overtake all valid refs from the old article into the new article, so that no information is lost.

I hope that this information about the new written article will start the discussion about the both article versions. (sorry for my English, I know it’s more Denglish, but I hope it is understandable in point of technical facts. --Elcap (talk) 15:47, 30 December 2014 (UTC)

It would be best if we could correct and reference the facts without making the text unreadable. --Wtshymanski (talk) 00:36, 31 December 2014 (UTC)
Correcting, ref the facts, deleting failures, that was it what I did! Point by point. However, I have added more chapters, a lot of new informations, pictures, tables etc. for better understanding. To make my text readable please help me in grammar --Elcap (talk) 10:32, 31 December 2014 (UTC)
As your user name has not appeared in any of the articles normally edited by Wtshymanski, you are probably unaware of what you have blundered into. Wtshymanski seems to erroneously believe that he owns all the engineering related articles on Wikipedia. Further he makes it difficult to impossible for anyone else to improve his articles. He will happliy edit war with anyone trying to change an article against what he believes the article should contain (often changing his argument to match whatever edit war he is pursuing - and in one case in adjacent discussions on the same talk page).
Reading through the two articles, I find the Elcap version a more comprehensive (and in many places accurate) discussion of the topic. It is moderately well referenced, but more references are of course better (though this was also a valid critisism of the old article). The English is not a significant problem because it can easily be copy-edited by other more able editors (as Elcap himself acknowledged when he tagged the new version as requiring CE). Similarly any contentious points can be similarly dealt with (including any useful material in the old article that has not made it into the new - I did spot one or two useful bits). DieSwartzPunkt (talk) 13:09, 31 December 2014 (UTC)
Hi DieSwartzPunkt, thank you for this information. Although I wrote the capacitor articles about Ceramic, film, types of caps and capacitor plague, and now new Al-e-cap, Ta-e-cap, and Nb-e-cap I up to now never have had difficulties with the WTShymanski. I will inset my article in two days and hope, that I can discuss all points on a technical level. Happy New Year to all users. --Elcap (talk) 15:51, 31 December 2014 (UTC)
@Elcap: OK, I've made a start. I have got up to (but not including) 'History'. I shall have a further stab later today or possibly tomorrow.
Do not let me stop anyone else having a crack at it! DieSwartzPunkt (talk) 14:44, 4 January 2015 (UTC)
──────────────────────────────────────────────────────────────────────────────────────────────────── Common history of the electrolytic capacitor concept should go here, with only metal-specific details in the subsidiary articles, where there is unique history to mention. Do we talk about the home=-made caps used in the early radio days, aluminum plates in jars of borax solution? --Wtshymanski (talk) 14:59, 5 January 2015 (UTC)

Electrolytic capacitor in crystal radio[edit]

The caption to an illustration claims that a 2 microfarad electrolytic capacitor was used in crystal radios. Quite apart from the fact there is nothing to decouple in a crystal radio, the only fixed capacitor likely to be found was that some designers put a capacitor of around 0.001 microfarads in parallel with the headphone (supposedly to shunt the residual R.F. from the crystal). In reality, removing it made no audible difference because the headphone was incapable of resolving radio frequencies. A 2 microfarad capacitor would have absolutely no use whatsoever. DieSwartzPunkt (talk) 16:45, 7 January 2015 (UTC)

In point of using this cpapacitor in a crystal radio you are absolutely right. I got this picture and the description from the file in Wiki Commons. Description: English: An early electrolytic capacitor from 1914. It consists of two sheets of foil about 3 cm square separated by a fabric sheet, immersed in an electrolyte solution, sealed inside a glass tube, with electrodes attached to the foils at either end. It had a capacitance on the order of 2 microfarads. It was used as a decoupling condenser in a crystal radio. Date before 1914, Source: Downloaded August 1, 2013 from William Henry Marchant 1914 Wireless Telegraphy: A handbook for the use of operators and students, Whittaker and Co., New York, p. 144, fig. 117 on Google Books
I have tried to calculate the capacitance of that capacitor out of the dimensions of the "plates", no etching, voltage proof appr. 10 V: the capacitance is somewhere in the order of 2 µF.
We shall delete "crystal radio" and write "one of the first published picture of an electrolytic capacitor (1914)" --Elcap (talk) 10:01, 8 January 2015 (UTC)

History, Tantalum quantity development[edit]

Hi DieSchwartzPunkt, your question is correct, thanks for your attention.

Source 1: The Tantalum Supply Chain: A Detailed Analysis [1]

Page 29, Fig. 13 The shortage of material may only have been perceived, but there was a real increase in the price of tantalum materials. The spot price for tantalum ore is as reported by the London Metals Bulletin (Fig. 13)…..

In the last 30 years, there have been two short periods when the tantalum ore price was unstable. In the late 1970s, the price of ore jumped, then returned to nearly the same as that before the excursion. In 2000, the price rose quickly, then again returned to normal. Figure 14 graphs the performance of tantalum powders from 1965 to the present.

Please have a look at Fig. 13 and 14

Source 2:

Tantalum Availability: 2000 and Beyond W. A. Serjak, H. Seyeda and Ch. G. Cymorek, H. C. Starck, Inc./GmbH [2]

Page 14

In 1999 and 2000, the supply chain became more complex than usual. Media reports highlighted the tight supplies and increasing prices, precipitating a scramble for capacitors and tantalum across the chain. Double ordering started. Worst of all, speculators entered the supply chain, disrupting the normal flow of material by bidding prices that were higher than existing supply chain prices.

Conclusion: My text in the chapter history, sorry, has to be changed a little bit. Proposal:

The solid tantalum capacitors in this years offered smaller capacitors with lower ESR values than the aluminum capacitors, However, they were more expensive. Nevertheless they found more and more applications, also in entertainment devices. That ends abruptly in the late 1970s, as a price explosion for tantalum ore the application in radios and TV sets makes too much expensive. Small Al-single ended e-caps with low leakage currents will replace the tantalums. With the beginning of the SMD technology the tantalums came back as chips for flat devices. --Elcap (talk) 16:02, 8 January 2015 (UTC)