hybridfree/eevblog-posts huggingface dataset:
Capacitor Plates? - Page 1
Forum section: electronics / beginners

author: THATguy
author_rank: Regular Contributor
timestamp: December 14, 2017, 10:12:44 pm
content: Do capacitor plates need to be made from the same type of metal?Could one be Alumium and the other gold?

author: mc172
author_rank: Frequent Contributor
timestamp: December 14, 2017, 10:37:00 pm
content: I don't actually know the answer, but in my mind, if your dielectric material is dry then I don't see why it would matter. However, if it's wet then you could end up with galvanic corrosion if the galvanic potential is above a certain threshold, which is usually considered to be over around 250 mV for mechanical structures. For electronic components I'd put it much lower - I would have thought that galvanic potential is completely undesirable and the higher the value, the lower the service life.From memory, aluminium and gold are around 1000 mV apart in the galvanic series which is quite a considerable potential!

author: nicalitz
author_rank: Regular Contributor
timestamp: December 14, 2017, 10:49:53 pm
content: I don't believe so. As long as both materials are relatively conductive and have a somewhat similar surface roughness, the capacitor should behave roughly the same.

author: nicalitz
author_rank: Regular Contributor
timestamp: December 14, 2017, 10:58:33 pm
content: This assumption obviously wouldn't hold for, say, supercapacitors, where the electrode material needs to react with the electrolyte in a very specific way. Might still be possible to use different materials, but it would get significantly more complex.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 14, 2017, 11:27:56 pm
content: Quote from: THATguy on December 14, 2017, 10:12:44 pmIf you are talking air gap or other physical insulating material besides electrolytic , then no they do not have to be the same type of metal. However, just remember that there is considerable engineering into making a GOOD capacitor that is to be used for a specific application.For experimental purposes, though, in order to understand capacitors, I think making your own home grown capacitors is a good learning experience.I thought this was a neat home made electrolytic capacitor.

author: Brumby
author_rank: Unknown
timestamp: December 15, 2017, 01:52:45 am
content: As said above, when considering the theoretical definition of a capacitor, especially with a dielectric such as air, it does not matter in the least.Where the materials DO matter comes into physical construction - and this is a topic of such immense proportions that I dare not venture into it. Even then, the metallic composition of the plates has more to do with electro-chemical stability and other considerations than it does with capacitance.
Capacitor Polarity - Page 1
Forum section: electronics / beginners

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: February 27, 2014, 06:14:48 pm
content: Capacitors are generally marked with a stripe to denote the negative polarity, correct?I ran into this the other day with a co-worker. He had a pcb with a small SMD capacitor on it. The PCB was marked +, but the capacitor had the stripe on it, soldered to the board at the + mark!!!found out that Tantalum SMD capacitors are marked this way. Could be a source of confusion.

author: tszaboo
author_rank: Super Contributor
timestamp: February 27, 2014, 06:17:19 pm
content: Yes, they made it to make our life miserable, then they soaked the capacitors in gasoline, at least they burn like that. The black ones are even worse, ans there is (standard) electrolyte in the same package, color.

author: mariush
author_rank: Super Contributor
timestamp: February 27, 2014, 06:37:14 pm
content: And then there's this:http://industrial.panasonic.com/ww/products_e/product_cat2/AAA8000_e/AAA8000_e.htmlOh, and don't forget about companies like Asus or Asrock that mark the electrolytics on their motherboards with the negative strip representing the positive side of the capacitors. Funny to read on forums how people blow up 6-10 capacitors at a time when repairing such boards...

author: Zero999
author_rank: Super Contributor
timestamp: February 27, 2014, 08:12:37 pm
content: I destroyed an SMT capacitor when I was an apprentice because of this.

author: uwezi
author_rank: Unknown
timestamp: February 27, 2014, 08:29:11 pm
content: When I was a master student (1996) I used to work for a small company, reworking circuit boards with SMDs at night. During the first night shift I finished I think a dozen boards and was proud as could be. The next day I was informed that someone else had to resolder all the tantalums on the boardI was confused, because I was sure to have respected the polarity of these capacitors, knowing that it was critical. But without ever having seen an SMD tantalum before I was not aware that manufacturers had formed a conspiracy by suddenly - and only for these components - marking the positive side with a broad line
Capacitor Polarity - Page 1
Forum section: electronics / beginners

author: dark_hawk
author_rank: Regular Contributor
timestamp: August 14, 2013, 02:00:57 pm
content: Hi,I have this Toshiba Laptop Charger I'm fixing, Had a problematic cap so I desoldered it and order on of the same capacitance and voltage (82uf 400V). Problem is the PCB has no indication for the cap polarity. (C051)How can I find the correct polarity.Thanks.

author: G7PSK
author_rank: Super Contributor
timestamp: August 14, 2013, 02:08:42 pm
content: My guess would be that it is non polarised as polarity is not shown, follow the circuit through to check where it goes if one trace to goes to a diode you will have the polarity.

author: PA0PBZ
author_rank: Super Contributor
timestamp: August 14, 2013, 02:11:06 pm
content: It looks like the main(s) filter cap right after the diode bridge, so it should not be too hard to figure out the polarity.

author: mariush
author_rank: Super Contributor
timestamp: August 14, 2013, 02:27:30 pm
content: Don't you see that black bar on the right side of the capacitor footprint? That's the NEGATIVE of the capacitor.

author: dark_hawk
author_rank: Regular Contributor
timestamp: August 14, 2013, 02:32:11 pm
content: That Simple huh.Thank you.

author: MrAureliusR
author_rank: Unknown
timestamp: August 14, 2013, 04:04:19 pm
content: Yeah, after some zooming in you can actually see the + and - symbols on the holes...
Capacitor prices ? - Page 1
Forum section: electronics / beginners

author: Hextejas
author_rank: Frequent Contributor
timestamp: July 02, 2018, 11:46:43 am
content: Why so much difference in the prices? I was pricing some parts for a power supply and i saw these 2.10,000uf, 50v1) 11.852) 41.58As far as I could tell they are the same so the disparity confuses me.The prices are from Mouser.Thanks

author: goldfinger
author_rank: Regular Contributor
timestamp: July 02, 2018, 11:55:40 am
content: Quote from: Hextejas on July 02, 2018, 11:46:43 amSpecs, ESR, snap in, solder lug, screw terminal all will impact cost. Like anything there is going to be variables, some attributed to brand markup and others quality. Higher uf caps you start seeing more of the esoteric caps so it isn’t a surpriseSent from my iPhone using Tapatalk

author: helius
author_rank: Super Contributor
timestamp: July 02, 2018, 12:15:13 pm
content: You didn't give any detail (such as links to the products in question, and Mouser lists90 differentproducts with those specs).Perhaps you meant:United Chemi-Con E36D500LPN103TA67M $11.85/singlesandVishay Sprague 36DY103F050AB2A $41.58/singlesWhen a company sells millions of products, it's safe to say that many of the pricing decisions are automated or semi-automated. Factors that can influence them include competitors' prices, available stock, estimated demand based on sales history, and manufacturing capacity forecasts. In some cases, a discontinued (NRND) part will have a lower price (to stimulate demand), or a higher price (based on requirements in approved designs).The electronic distributors also provide different packaging options with different prices, like bulk, full reels, trays, loose, and custom reels. Their outlets in different countries also have regulatory, tax, and logistical issues that vary the prices.In this case, the main difference is the manufacturers. I would expect that certain customers, like defense contractors, have strict Country Of Origin requirements that limit their choices. So prices are segmented accordingly.

author: BravoV
author_rank: Super Contributor
timestamp: July 02, 2018, 12:28:21 pm
content: You should improve on how to ask ...
Capacitor question - Page 1
Forum section: electronics / beginners

author: Crambone
author_rank: Frequent Contributor
timestamp: August 13, 2020, 08:46:58 pm
content: Hello, are Mylar and Polyester Film Capacitors interchangeable?

author: magic
author_rank: Super Contributor
timestamp: August 13, 2020, 09:13:28 pm
content: Yes, it's the same material also known as PET.Polypropylene, polystyrene, PPS, teflon - these are different.

author: Crambone
author_rank: Frequent Contributor
timestamp: August 13, 2020, 09:38:08 pm
content: Thank you

author: TimFox
author_rank: Super Contributor
timestamp: August 13, 2020, 10:17:24 pm
content: Mylar is a registered trademark for DuPont’s polyester, which is technically polyethylene terephtalate, hence the abbreviation PET. Capacitor manufacturers don’t say Mylar due to the trademark.
Capacitor question - Page 1
Forum section: electronics / beginners

author: digik
author_rank: Regular Contributor
timestamp: August 19, 2024, 09:19:37 am
content: This may seems a strange question, but I was wondering if I can use a regular X2 capacitor to make an oscillator circuit with an opamp (100kHz max).Someboby says that X2 caps are not good for this purpose, but since i have lots of X2 caps, before i order "proper" polypropilene caps I want to know your opinion.Thanks

author: RoGeorge
author_rank: Super Contributor
timestamp: August 19, 2024, 09:44:20 am
content: Should work.Beware many opamps might struggle working at 100kHz (depending of the oscillator type and of the opamp model). What's the schematic?

author: digik
author_rank: Regular Contributor
timestamp: August 19, 2024, 10:11:41 am
content: No schematic is al TL084CN simply for fun:

author: RoGeorge
author_rank: Super Contributor
timestamp: August 19, 2024, 12:39:52 pm
content: Looks like no problems and all the fun!

author: Gyro
author_rank: Super Contributor
timestamp: August 19, 2024, 06:02:47 pm
content: X2 caps are only a problem in high voltage stress, high transient current applications, where they may self-heal and lose capacitance. You're in no danger of such capacitance changes in an opamp circuit. In some applications youmightnotice a higher ESR / lower Q than 'standard' MKP capacitors due to the thinner , more resistive, metalization.Your biggest issue is probably wider value tolerance.
Capacitor Questions - Page 1
Forum section: electronics / beginners

author: Sublime
author_rank: Contributor
timestamp: July 12, 2015, 05:46:35 am
content: I'm pretty new to this, and I've just been constantly studying and watching videos on everything about electricity and soldering and components. I've been watching EEVBlog for quite a while, as well as quite a few other people, and I've recently been tearing down my own things to further understand things on a hands on level. Well, one question I have is this: I've heard Dave and a few others mention to be careful with 200V capacitors and that they could really hurt and shock you, even if unplugged. Can someone expand on this? How can one be shocked by a capacitor? Touch the metal prongs? Or is it only if your skin is charged? What is a safe way to discharge a 200V Capacitor? I saw one comment say they were shocked after a week of leaving their device unplugged. How long do I have to wait?

author: Stonent
author_rank: Super Contributor
timestamp: July 12, 2015, 06:02:36 am
content: Well capacitors are somewhat like small rechargeable batteries that can put almost all their power behind a discharge. The capacity is rated in Farads, or usually MicroFarads (uF), NanoFarads (nF) and PicoFarads (pF).I doubt nF and pF will hold anything long enough to hurt you if the device has been off for a while.If you're in doubt, usually a screwdriver across the terminals is a good way to discharge. Be warned though that sometimes a capacitor will cause the screwdriver to stick because capacitors can put a lot of Amps behind their discharge. The more farads, the longer they will hold a charge and the more energy will be behind the discharge.Whenever working with higher voltage, do not put yourself in a situation were electricity could go through one arm and out the other. That's how you can get killed, so keep an arm behind your back.In this video a 2.7 volt 2600 Farad capacitor is used to do some welding.

author: Stonent
author_rank: Super Contributor
timestamp: July 12, 2015, 06:18:53 am
content: I'd also recommend this video:

author: Sublime
author_rank: Contributor
timestamp: July 12, 2015, 06:35:09 am
content: Thank you!!! That is much appreciated!
Capacitor rateing - Page 1
Forum section: electronics / beginners

author: thedoc298
author_rank: Contributor
timestamp: April 02, 2019, 01:19:06 am
content: Does anyone know what frequency are cornell dubilier 942C20P15K-F capacitors rated. Can't seem to find any info. Thanks.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 02, 2019, 02:24:18 am
content: Quote from: thedoc298 on April 02, 2019, 01:19:06 amHi,The datasheet is here:http://www.cde.com/resources/catalogs/942C.pdfOn the datasheet there is this graph for the 2000V parts:Regards,Jay_Diddy_B

author: thedoc298
author_rank: Contributor
timestamp: April 02, 2019, 02:27:56 am
content: Thanks so much, have a head ache looking. Made my evening. Thanks again.
capacitor reformation speed question - Page 1
Forum section: electronics / beginners

author: RSX11M+
author_rank: Newbie
timestamp: August 28, 2024, 12:53:43 am
content: hey all! i am working on reforming some old beer can caps from mallory, 130kuF@15VDC and 29000kuF@25VDC. they are part of the linear power supply in an old cromemco microcomputer.i've been advised to reform the caps by setting the voltage on my bench psu to the rated voltage of each cap and then slowly bring it up using low (<10mA) current (increading slightly as voltage gains drop off), so i am doing that starting at 1mA. i expected the voltage to rise very slowly, but the cap reached 2V of 15 inside of 3 minutes and i, feeling a little bit nervous, pulled the plug temporarily.my question is, is there a rate at which a cap can be considered to be reforming "too quickly"? i am a bit concerned about these caps exploding as they are quite beefy, but if this is to be expected then i am fine continuing.thank you for any insight you can provide!

author: gbaddeley
author_rank: Regular Contributor
timestamp: August 28, 2024, 03:10:13 am
content: Start at 10mA limit & 10V limit. The current should go down below 1mA after some time, eg. 1 hour.
Capacitor replacement question - Page 1
Forum section: electronics / beginners

author: gkmaia
author_rank: Frequent Contributor
timestamp: February 23, 2019, 08:39:20 am
content: Is it ok to replace these orange capacitors by these polypropylene ones?They are part of the CRT power supply high voltage block. CRT runs at 1500v.Also, I suspect the high voltage ceramic may not work for this use, but I do not understand why. Can anyone clarify a bit?

author: SeanB
author_rank: Super Contributor
timestamp: February 23, 2019, 10:00:11 am
content: Ceramic capacitors will have a wide tolerance, thus your actual capacitance will depend on how long since they have been soldered, the actual material they are made from. This will mean capacitance will vary with temperature and applied voltage, possibly quite a bit, and the film capacitor however will not vary much in capacitance both from new, with time and with applied voltage and temperature. As they are pretty much the same price wise go with the foil one.

author: gkmaia
author_rank: Frequent Contributor
timestamp: February 23, 2019, 10:08:06 am
content: Quote from: SeanB on February 23, 2019, 10:00:11 amBy foil one you mean polypropylene?

author: jackthomson41
author_rank: Regular Contributor
timestamp: February 23, 2019, 11:45:39 am
content: Quote from: gkmaia on February 23, 2019, 10:08:06 amBy foil, he meant ceramic capacitors.https://www.theengineeringprojects.com/2021/03/what-is-physics-definition-branches-books-and-scientists.html

author: ebastler
author_rank: Super Contributor
timestamp: February 23, 2019, 11:58:18 am
content: Quote from: jackthomson41 on February 23, 2019, 11:45:39 amNo, he obviously didnot. SeanB argued that foil (film) capacitors are preferrable, since they have better tolerance and stability than ceramics. And hence he recommended to use foil caps, since their price is similar to ceramic caps.

author: David Hess
author_rank: Super Contributor
timestamp: February 23, 2019, 10:18:18 pm
content: High voltage polypropylene film capacitors will work fine. High voltage ceramic capacitors will also work fine. The only plastic film capacitor which could be problematical is polystyrene because of its low maximum temperature and high operating temperatures around typical CRTs.
Capacitor replacement question. - Page 1
Forum section: electronics / beginners

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 18, 2018, 02:26:52 pm
content: I am reading the thread about tearing down a Tektronix scope. he is replacing a 11000MFD 15v with a 22000MFD 25v.He seems to know what he is doing though whenever I replace capacitors I try to get the same sizes and types.So, as he did, can I always go bigger when replacing capacitors ?

author: ataradov
author_rank: Super Contributor
timestamp: September 18, 2018, 02:44:04 pm
content: Not always. Depends on the capacitor location in the circuit.You can almost always go higher on bulk capacitors in the power supply. But if capacitor is used in a filter, changing the specs will change the filter characteristics.

author: Zero999
author_rank: Super Contributor
timestamp: September 18, 2018, 04:08:46 pm
content: Yes, in a bulk filtering application, it's generally fine to go larger, the main downside is the inrush current surge will increase, which could cause problems with the fuse and/or rectifiers blowing.

author: Tandy
author_rank: Frequent Contributor
timestamp: September 18, 2018, 04:39:33 pm
content: A lot of switch mode power supplies use cheap high ESR capacitors for smoothing that heat up due to ripple. Using low ESR capacitors generally results in longer life, also uprating to a higher capacitance also means that, assuming the dielectric is the same thickness then extra capacitance is achieved by increasing the plate area. As the plate area increases, the ESR will go down reducing the damage caused by heating.Also if you think about it increasing the capacitance means that the replacement has a head start so to speak. As it ages it will take a while before the new higher value degrades to the lower capacitance of the original, therefore the time before it needs replacing again will be extended.
Capacitor Replacements and Tolerance Values  - Page 1
Forum section: electronics / beginners

author: Bskitter
author_rank: Regular Contributor
timestamp: October 29, 2016, 01:09:24 pm
content: Hi Guys,I am replacing some Caps on an old Kenwood Amplifier,I tested the main smoothing caps after the rectifier, they are rated at 6800 uf, 3 of the 4 are around this value, the 4th on is at about 6200 uf, should this cap be replaced ?Secondly I am replacing some Ceramic Caps @ 0.01 uf, now the ones on the board are a lot bigger than the same caps you get today, is it some new process that made these caps smaller or is their voltage rating higher than the standard one ?These caps are also near the rectifier and the RMS output by the TF is 30 Volts.On the parts sheet it saysCeramic 0.01uf +100% -0%.I do not understand the percantages, could some please explain what they mean ?The same goes for other caps I am replacing,Mylar 0.15uf +-10%,The percentage rating here is more understandable since it seems like the tolerance rating of that cap but +100 - 0% is confusing.RegardsByron

author: wraper
author_rank: Unknown
timestamp: October 29, 2016, 01:21:16 pm
content: Most of the electrolytic capacitors have +/- 20% tolerance. Large capacitors often have +80 / -20% tolerance.so 6200 uF should be well within the tolerance. FIY measuring capacitance will thell that something wrong with the capacitance only if capacitor is completely dead. You need ESR meter or LCR meter with ESR measurment to check if they are fine. Also, if you are using multimeter for electrolytic capacitor measurments, results won't be precise. Multimeters measure capacitors by not standardized way (LCR meters measure capacitance at particular frequency, the same way as capacitor datasheets specify), therefore parasitic effects in electrolytic capacitors will affect the measurements a lot.QuoteMeans what it says. Capacitance value can be up to twice of the written.

author: P90
author_rank: Frequent Contributor
timestamp: October 29, 2016, 01:28:04 pm
content: Replace those electrolytics with good name brand caps, make sure you don't get fakes on ebay...

author: tggzzz
author_rank: Super Contributor
timestamp: October 29, 2016, 02:50:23 pm
content: Quote from: wraper on October 29, 2016, 01:21:16 pmCaution: the dielectric is important. For X7R and Y5U dielectrics, the capacitance can fall to only 20% (!) of the stated value when a DC voltage is applied. (I wonder if they could be used in place of a varicap diode?)Many manufacturers don't define this clearly, the better ones do. See, for examplehttps://product.tdk.com/en/search/capacitor/ceramic/mlcc/info?part_no=C1005X7R1H103K050BESome claim that Murata are the least bad in this respect; I have no opinion.
Capacitor safety valve question - Page 1
Forum section: electronics / beginners

author: Greg65
author_rank: Contributor
timestamp: March 26, 2014, 04:42:06 pm
content: Hi everyone,When the plastic top of the big PSU capacitors has popped up and the aluminium top of the capacitor is beginning to bulge upwards, is this a sign that the capacitors need replaced and is this a sign that they are ready to pop at anytime?Please take a look at the pic.Thank you!

author: Shock
author_rank: Super Contributor
timestamp: March 26, 2014, 05:19:57 pm
content: The plastic tops are just a cover and doesn't mean much, you can pull one or all off to inspect if the aluminum is bulged at all.If it's faulty though and still in warranty you don't want to mess with it. Less blaming game hassles when you send it in.What counts is if the capacitors are ok.Which can be tested by measuring the capacitance value and ESR value of some (all if the amps faulty) to see if the capacitor is going out of spec.If the amp is known to fail your really looking just a few possibilities:Caps are a cheap brand and failing early. You can replace them with a better brand.Caps are overheating and failing early (which could be the whole amp is too hot). Replace them with a higher temp rating.Caps are incorrectly spec'd for the circuit. Replace with correct cap.If nothing is wrong with the amp and no bulging and you can't find anything to justify replacing them then your all good.
Capacitor selection for low output ripple and relativly high voltage - Page 1
Forum section: electronics / beginners

author: Chrische
author_rank: Newbie
timestamp: October 06, 2016, 05:38:48 pm
content: I got a question regarding the ripple reduction of switch mode power supplies. The problem is the following:I got at boost converter, that boosts a voltage up to 18V.The operation frequency of the boost converter is fixed at 1.2Mhz.The real problem is the voltage ripple of the output. What options do i really have in reducing the voltage ripple. Ceramic capacitors seem to work well at that frequency, but certainly not at that dc bias voltage.Aluminum and Tantalum seems to have their resonant frequency below the operation frequency if I'm not mistaken (hard to figure out from the datasheets).Is the only way to change the design and use a boost converter that operates at a lower frequency or am I missing something here?the maximum output current of the converter is around 300mA.

author: rob77
author_rank: Super Contributor
timestamp: October 06, 2016, 06:23:58 pm
content: i would just suggest to use a ceramic caps with higher capacity or even 2-3 of them in parallel.

author: SeanB
author_rank: Super Contributor
timestamp: October 06, 2016, 06:28:03 pm
content: How about a LC filter ( using a very lossy inductor or you can make it worse) to reduce the ripple and noise. Then you can use ceramic capacitors, and get a very good attenuation.
Capacitor size vs Ripple voltage - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: April 18, 2024, 08:20:44 am
content: I have a question.Does the size of an MLCC 0201 capacitor when compared to 0603 MLCC capacitor of the same value have produce different effects on ripple voltage?Like, does the size of the capacitor (0201 vs 0603) have any impact on the ripple voltage of a power rail?

author: mariush
author_rank: Super Contributor
timestamp: April 18, 2024, 08:27:40 am
content: Have a read athttps://pdfserv.maximintegrated.com/en/an/TUT5527.pdf- Temperature and Voltage Variation of Ceramic Capacitors, or Why Your 4.7µF Capacitor Becomes a 0.33µF Capacitor
Capacitor substitution - Page 1
Forum section: electronics / beginners

author: openground
author_rank: Newbie
timestamp: December 31, 2010, 11:36:18 pm
content: could I use polystyrene caps to replace electrolytics? say 22uF &10uF - sorry for the change,I'm building a home made esr meter and have these on hand-ref : www.ludens.cl/Electron/esr/esr.html

author: Simon
author_rank: Unknown
timestamp: January 01, 2011, 01:42:35 am
content: it depends on the purpose they serve, are you changing for the same values ? more information is needed for a proper answer

author: Zero999
author_rank: Super Contributor
timestamp: January 01, 2011, 02:12:16 am
content: You could but polystyrene capacitors in those values would be huge so would be too big to fit a PCB designed for electrolytics.

author: openground
author_rank: Newbie
timestamp: January 01, 2011, 02:34:21 am
content: Thanks, I was wondering as electrolytics do tend to degrade over usage/time and thought their usage in an ESR meter would be counter productive (over time) for accuracy of the meter itself.www.ludens.cl/Electron/esr/esr.html

author: Zero999
author_rank: Super Contributor
timestamp: January 01, 2011, 02:45:45 am
content: The link doesn't work. I suggest you look at where the electrolytic capacitors are used in the ESR. If it's designed correctly the should only be used for supply decoupling, AC coupling in reasonably high impedance amplifiers or filters where ESR isn't too critical.

author: openground
author_rank: Newbie
timestamp: January 01, 2011, 03:17:34 am
content: fixed the link, but I believe you answered my question, Thanks!
Capacitor Surface Mount question - Page 1
Forum section: electronics / beginners

author: Crambone
author_rank: Frequent Contributor
timestamp: December 31, 2024, 08:12:17 pm
content: I’m looking for a 20n 1kv surface mount capacitor, it measures 3.2mm long, 1.5mm wide & Depth dosent mattterAndrew

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: December 31, 2024, 11:05:18 pm
content: You didn’t look very far. Took a few seconds on Mouser.com Part number 581-1812AC203KAT1ASJ

author: thm_w
author_rank: Super Contributor
timestamp: December 31, 2024, 11:11:18 pm
content: The 1812 above is:Length: 4.5 mm (0.177 in)Width: 3.2 mm (0.126 in)Height: 2.54 mm (0.1 in)So yours might be 1206Possibly either would fit.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: December 31, 2024, 11:17:06 pm
content: Oops, 1206 size at Mouser 80-C1206C223KDRAUTOSJ

author: wraper
author_rank: Unknown
timestamp: December 31, 2024, 11:33:29 pm
content: Quote from: Crambone on December 31, 2024, 08:12:17 pmIt's easy to find a suitable part in 1206 or 1210 package in any catalog using parametric search.https://eu.mouser.com/c/passive-components/capacitors/ceramic-capacitors/mlccs-multilayer-ceramic-capacitors/multilayer-ceramic-capacitors-mlcc-smd-smt/?capacitance=0.022%20uF&case%20code%20-%20in=1206&voltage%20rating%20dc=1%20kVDC

author: Crambone
author_rank: Frequent Contributor
timestamp: January 01, 2025, 12:01:11 am
content: Thanks guys the surface mount is new to meDrew
Capacitor swap - Page 1
Forum section: electronics / beginners

author: Znfrlj
author_rank: Newbie
timestamp: December 15, 2018, 11:02:54 am
content: Hi,I am trying to fix a bad Samsung LCD power supply (running on AC 230V mains).If I swap the bad 100uF 450V cap with a 100uF 400V I have at hand, it should be ok. Right?The peak AC voltage should not exceed 325V +/- 15V.Thanks!

author: Psi
author_rank: Super Contributor
timestamp: December 15, 2018, 11:37:32 am
content: It should be ok just to test with. To see if that's the problem or not.But once you fix it permanently i would replace with 450V

author: Znfrlj
author_rank: Newbie
timestamp: December 15, 2018, 12:09:07 pm
content: Ok, thanks!
Capacitor Tee: can the capacitory be all different - Page 1
Forum section: electronics / beginners

author: Bigman
author_rank: Regular Contributor
timestamp: June 04, 2015, 02:42:45 pm
content: Hi,in a book I came across the attached circuit. In order to fine-tune the capacitor in the feedback loop, this book suggest a tee-network with a trimmer.I am wondering: can the capacitors C1and C2have a different capacity or should C1=C2?

author: TimFox
author_rank: Super Contributor
timestamp: June 04, 2015, 03:23:38 pm
content: They can all be different.Typically, to obtain the effect of a small feedback capacitance, C1 is the smallest.If C1 << C2, C3, then the effective feedback is less than C1, and there is an additional input capacitance of approximately C1.The tee network is exactly equivalent to a pi network (using those equations) and independent of frequency if all impedances are the same type (capacitor, inductor, or resistor).Also note that the op amp must be happy driving the series combination of C2 and C3 to ground (not too huge).

author: Bigman
author_rank: Regular Contributor
timestamp: June 04, 2015, 03:35:11 pm
content: @TimFox: Thanks for your nice reply.
Capacitor testers / testing. - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 20, 2012, 08:39:18 pm
content: I would like to be able to do some basic testing of capacitors, i have already landed myself with a device that has been stood for years, powers up fine, but today, after being left on for a few hours failed with what i guess may be a power supply issue, I am new to electronics, but fancy a go at fixing it myself. It cost very little, if it all goes wrong its experience I suppose. What devices are around Internationally as I am in the UK, that are known to work OK and aren't mega money? I Googled capacitor testing and there are dozens of opinions on ways to do it. I have a half decent hand held multimeter, and a bench multimeter, but neither have a built in capacitance testing setup. I also read of using a scope and a frequency generator, and look at the DC offset, but it sounds a bit involved, although I do have a basic scope and a cheap signal generator. Thanks

author: Mint.
author_rank: Frequent Contributor
timestamp: January 20, 2012, 08:47:58 pm
content: Bump. Interested

author: IanB
author_rank: Super Contributor
timestamp: January 20, 2012, 09:36:33 pm
content: I think people here will be better able to help you if you can be more specific about what aspects you want to test and what your goals are?For instance do you want to do a basic test for capacity? Test for ESR? Test for leakage? Do you want to identify unknown capacitors, or look for faults in existing capacitors? Etc...

author: kripton2035
author_rank: Super Contributor
timestamp: January 20, 2012, 09:58:07 pm
content: go to my web site and pickup and build yourself an esr meterso you will be able to detect 99% of faulty capacitors, especially in power supplieshttp://kripton2035.free.fr/esr-repository.html

author: Rerouter
author_rank: Super Contributor
timestamp: January 20, 2012, 10:01:41 pm
content: Now just as a starting point if you pretty much only have a multimeter,99.9% of the time if a capacitor has failed, it is an electrolytic or a tantalumboth can be given the same basic checks, but these are just crude checks which test the most basic operation1. on ohms setting, measure across the legs of the capacitor, while there may be some components in parrellel with it, the value should not be a short,2. using the diode test, hold your leads to the legs of the capacitor (IN THE CORRECT POLARITY) and wait until the value seems to level out, then switch to voltage and see that its holding somewhere near 2.2-3V (depending on value it will start discharging through the multimeter, and may seem to drop like a rock for less than 100n)but yeah if you can, an esr meter is a much better tool to find problems, those checks are only as a starting point
Capacitor tolerance - Page 1
Forum section: electronics / beginners

author: miketan3904
author_rank: Contributor
timestamp: June 11, 2020, 06:22:37 am
content: Hi! For resistor, we know that the tolerance of certain group of resistor can be known from the name of the series. For exemple, E96 series would mean that the resistors have a tolerance of 1%. I would like to know if there is such name for capacitor so that we could know the tolerance of the capacitor. Thank you.

author: TimFox
author_rank: Super Contributor
timestamp: June 11, 2020, 01:23:24 pm
content: The "E" numbers do not define tolerance, they define the discrete steps available."E24" means 1.0, 1.1, 1.2, etc.With resistors, usually the manufacturer makes available all the values from his minimum to maximum value, so 1% resistors are available in all the E96 values.However, usually capacitor manufacturers do not produce all the values, even if they sell 1% tolerance units, since there is less demand for a "dense" set of values.For both resistors and capacitors, the standard notation for tolerance is a letter following the number, e.g. "5112F" for a resistor means 51,100 ohms, 1% tolerance and "102J" for a capacitor means 1000 pF (1.0 nF), 5% tolerance. The common codes are K for 10%, J for 5%, and F for 1%

author: Siwastaja
author_rank: Super Contributor
timestamp: June 11, 2020, 04:27:14 pm
content: It's in the part number / datasheet, like all other parameters.Contrary to common misbelief, E series name has absolutely nothing to do with tolerance with resistors, except by luck. Of course, very fine-stepped series often do have good tolerance as well because it wouldn't make sense to manufacture a rarely needed "odd" value with poor tolerance because they are typically used in circuits where that particular value is needed.Part markings are getting less and less relevant. The number of stripes in color codes blew up, and small SMD parts have no space to fit printed text. Order known parts with datasheets available and don't mix them up after ordering.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 12, 2020, 06:38:59 am
content: Tolerances of capacitors can be somewhat deduced from the type of capacitor.Electrolytic capacitors often have very coarse tolerances such as -10 to +40%.Some types of ceramic capacitors may have a change of 50% of their capacitance when a DC voltage is applied, so a fine tolerance would be useless.Film capacitors can have tight tolerances.Silver Mica are still the best as far as I know, but a bit on the expensive side of the universe.

author: WattsThat
author_rank: Frequent Contributor
timestamp: June 12, 2020, 03:46:19 pm
content: EEVBlog 32&33 Has a pretty good explanation on capacitor tolerances
Capacitor Tolerance? - Page 1
Forum section: electronics / beginners

author: MikeSW17
author_rank: Newbie
timestamp: July 28, 2018, 11:36:32 am
content: Is it always (usually?) best to use a close tolerance capacitor?Put another way. I like building electronic DIY kits, I usually meter the components as well as checking the markings.I know my metering device is probably crappy - but it does give consistent results on repeat tests of a given capacitor.What I'm wondering is, if I have say a few 100pF ceramics in a kit and they measure say between 87pF and 112pF, is it worth me digging through my general stock for, say caps between 95pF and 105pF (or better)?I'm sure the answer will be 'it depends on the circuit'; I know that say a RC filter or oscillator will be more accurate with high tolerance parts.But more generally does 10-20% tolerance really matter given that the designer should have accounted for expected variances?I guess the question is, what do other people do; go with all caps (etc) supplied as is (obviously not using and real duds) or try and 'better' the circuit?

author: Brumby
author_rank: Unknown
timestamp: July 28, 2018, 11:47:39 am
content: Absolute accuracy of value - a.k.a. tolerance - is not a big issue in quite a lot of cases. What is often more important is stability - that the value doesn't change with environmental conditions and age, but the importance of that also depends on the application. Reliability is another factor.If you have a few 100pF ceramics, I wouldn't be worrying about measuring them for the sort of applications in which they tend to appear.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 28, 2018, 12:15:11 pm
content: For quite some applications the tolerance (and stability) of capacitance does not matter. Examples are power supply decoupling and AC coupling caps.As low tolerance caps are rare one usually tries to avoid them and if really needed, there should be a note on the caps to use.There are a few circuits that like matching caps (e.g filters with differential amps).
Capacitor Type? - Page 1
Forum section: electronics / beginners

author: tony3d
author_rank: Frequent Contributor
timestamp: October 08, 2013, 03:53:46 pm
content: Hi All, going through the parts I have bought so far I came across this electrolytic Cap that I think is non polarized. It's not marked that, and there are no other indications of polarity, but I do see BP down the side. Is this a bi-polarized cap, and if so can it be used just as a non polarized cap?

author: Hideki
author_rank: Frequent Contributor
timestamp: October 08, 2013, 04:07:29 pm
content: Your guessed correctly.

author: tony3d
author_rank: Frequent Contributor
timestamp: October 08, 2013, 04:16:57 pm
content: Thank you. Can you explain what the differences are between a bi-polarized, and non-polarized cap?

author: And!
author_rank: Contributor
timestamp: October 08, 2013, 06:32:31 pm
content: Two identical polarized electrolytic capacitors connected together with eg. negative terminations, creating bipolarized capacitor with 50% of capacitance.I think there is no difference between bipolarized and nonpolarized capacitor,they simply nonpolar.

author: Paul Price
author_rank: Super Contributor
timestamp: October 08, 2013, 10:39:47 pm
content: Andl,Maybe a typo on your pat, but there can be an explosive difference between polarized and non-polarized caps.

author: And!
author_rank: Contributor
timestamp: October 12, 2013, 12:44:30 pm
content: Yes this is a typo, thanks I corrected.
Capacitor Value - Page 1
Forum section: electronics / beginners

author: Old Believer
author_rank: Newbie
timestamp: May 14, 2025, 04:53:17 pm
content: I know I'm old, but I still have a mind that enjoys some stimulation, so I occasionally tinker with old junk that I will probably never use. My latest venture into the obsolete involves a 40 year old laser level which I suspect is ailing from a bad capacitor. However, my dusty mind cannot seem to decipher the value associated with the pictured capacitor. Would someone be so kind as to enlighten me to its capacitance and max voltage? Electronics consultants in my locality seem to be as obsolete as the aforementioned laser level. Hopefully the photo is properly attached. Thanks in advance.

author: Uunoctium
author_rank: Frequent Contributor
timestamp: May 14, 2025, 05:01:14 pm
content: I think it's an Tantalum capacitor 100µF, 20V, polarity marked +

author: Gyro
author_rank: Super Contributor
timestamp: May 14, 2025, 06:20:22 pm
content: Yes, that's right.Tantalum bead caps rarely lose capacitance value but can become leaky - or short circuit if there's enough current available. If it's on a supply rail, make sure there is reasonable headroom on the rating, eg. Don't use a 20V cap on a rail higher than about 15V. If it's being used as an element in a timing circuit, significant leakage could throw it off.P.S. Welcome!

author: David Hess
author_rank: Super Contributor
timestamp: May 14, 2025, 07:27:26 pm
content: That is a dipped epoxy solid tantalum capacitor with values of 100 microfarads and 20 volts. I know it cannot be 100 volts, because dipped epoxy solid tantalum capacitors are only available up to 50 volts. Stress from the epoxy coating and humidity changes prevent reliable operation above 50 volts.

author: Old Believer
author_rank: Newbie
timestamp: May 15, 2025, 04:57:15 pm
content: Thanks for your kind responses. The capacitor is connected between the secondary's + and - terminals of a DC to DC converter (6v to 12v.) The unsoldered converter appears to be functioning. With the converter back on the board and the capacitor in place the secondary voltage drops to <1v. With the capacitor removed, the circuit has 12v. I guess I'll find out if a replacement capacitor fixes the problem. I only have a digital VOM to check the capacitor, and it checked out as kind of iffy. Anyway, your responses were appreciated.
capacitor value tolerance in Kit Radio Pixie 40m cw qrp - Page 1
Forum section: electronics / beginners

author: vinlove
author_rank: Frequent Contributor
timestamp: July 19, 2019, 09:24:19 pm
content: I am building Pixie 40m CW QRP kit from eBay. This kit was bought about 3-4 year ago, but was left in the drawer, and had been forgotten all this time.I found it a few days ago while clearing out, and I thought will have a go building it.I soldered all the resistors on the board, and now its time to put on the capacitors.The capacitor value for C1, C10 on the paper is 0.1uF (104).But when I checked them with my DMM, their value is 65 pF. I would think it is 0.065uF? which is about 35-40% off from the spec.?Are these within the usable tolerance, or these caps have gone off?Thanks.

author: floobydust
author_rank: Super Contributor
timestamp: July 20, 2019, 12:53:53 am
content: Check your build, post a schematic or something

author: vinlove
author_rank: Frequent Contributor
timestamp: July 20, 2019, 08:26:59 am
content: On my sheet, both C1 and C10 is 0.1 uF (104).

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 20, 2019, 09:43:29 am
content: Both C1 and C10 are not critical, 0.1u (or 100n) would be fine in the schematic floobydust posted. But get your units correct: 65p is 0.065n = 0.000065uMy guess is that you are not measuring correctly, can you post a picture of the caps?

author: vinlove
author_rank: Frequent Contributor
timestamp: July 20, 2019, 11:10:02 am
content: Quote from: PA0PBZ on July 20, 2019, 09:43:29 amI was using 3x different DMMs for the measurement, and they all showed same figures, but I think I wrote wrong on my OP. It must be 65nP, not pF.I will check it again and update later.

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 20, 2019, 12:06:49 pm
content: 65nF should not be a problem in the above schematic.

author: vinlove
author_rank: Frequent Contributor
timestamp: July 20, 2019, 02:05:06 pm
content: Quote from: PA0PBZ on July 20, 2019, 12:06:49 pmThank you for your confirmation.)
capacitor values - Page 1
Forum section: electronics / beginners

author: silly sausage
author_rank: Regular Contributor
timestamp: January 26, 2025, 09:43:23 pm
content: I have just seen a schematic from the 1950's it has a few cap values in uufd, would that mean pico-farad?,thanks.

author: bdunham7
author_rank: Super Contributor
timestamp: January 26, 2025, 09:44:18 pm
content: Yes

author: tooki
author_rank: Super Contributor
timestamp: January 26, 2025, 09:45:43 pm
content: Yep:https://en.wikipedia.org/wiki/Farad#Informal_and_deprecated_terminology

author: TimFox
author_rank: Super Contributor
timestamp: January 26, 2025, 10:55:38 pm
content: From that era, you may also find "mmfd" as an abbreviation for pF.

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 27, 2025, 05:19:30 am
content: Pf the picofarad.....
capacitor. what is happening in this circuit ? - Page 1
Forum section: electronics / beginners

author: elektronJack
author_rank: Contributor
timestamp: February 02, 2020, 01:20:58 pm
content: Both switches are open at the beginning.When i close sw1 the led doesn't illuminate.If i open sw1 then close sw2 the led doesn'tilluminate.However if i then open sw2 then close sw1 the led flashes once only. I understand that it has something to do with the capacitor buti can't understand the current flows.

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: February 02, 2020, 01:38:12 pm
content: When you close SW1, the capacitor gets charged through the series path of the resistor and the LED. It charges us quite quickly and then the current drops to zero. Thats why you see the LED blink.With SW2 closed, the current is too low (the series resistor is in KOhms) and hence the LED does not glow.The circuit behaves well as drawn.

author: Wimberleytech
author_rank: Super Contributor
timestamp: February 02, 2020, 01:44:41 pm
content: When you close SW2 while SW1 is open, any charge that might be on the capacitor is discharged. Thus the voltage across the capacitor is zero volts.When you open SW2 (SW1 still open), nothing changes...there is still zero volts across the capacitor.The physics of how a capacitor works says that the voltage across a capacitor cannot change instantaneously.So, when you close SW1, the + side of the capacitor rises instantly to about 12 volts. Because the voltage across the capacitor cannot change instantly, the - side of the capacitor ALSO rises to about 12 volts and THEN begins discharging through the LED. The time constant is pretty fast (milliseconds), so you only see a quick blink.
Capacitor - Page 1
Forum section: electronics / beginners

author: ethhanners
author_rank: Contributor
timestamp: February 14, 2014, 03:25:09 am
content: so I am new to electronics and I was wondering do capacitors keep charging like if I had a one voly supply and a 22 v capacitor would the voltage increase to 22 volts

author: Rudane
author_rank: Regular Contributor
timestamp: February 14, 2014, 03:28:25 am
content: The cap would stop charging at 1 Volt. You need a difference in voltage to get current to flow. If you hook up the cap, initially it will be 0 volts and increase until it reaches 1 volt. Then, since there is no voltage difference, the cap would stop charging. Warning, don't hook a cap up directly like that, always use a resistor to limit the initial current flow.

author: ethhanners
author_rank: Contributor
timestamp: February 14, 2014, 03:29:22 am
content: ok thank you

author: rstoer
author_rank: Regular Contributor
timestamp: February 14, 2014, 05:44:22 pm
content: BTW: The 22v rating you refer to is the maximum voltage the capacitor can be charged to.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: February 15, 2014, 12:49:31 am
content: The 22v rating is the maximumsafevoltage the capacitor can be charged to. You will be able to charge it to beyond 22V but at some point it will fail, perhaps catastrophically.