# What does a capacitor do? **URL:** \ **Category:** Factual Questions\ **Created:** [April 14, 2010, 7:24pm UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106 "2010-04-14T19:24:41Z")\ **Posts on this page:** 7\ **Page:** 4
**Author:** ![JoeH2O](https://avatars.discourse-cdn.com/v4/letter/j/9de053/32.png) [@JoeH2O](https://boards.straightdope.com/u/JoeH2O)\ **Post date:** [June 18, 2010, 6:09pm UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106/61 "2010-06-18T18:09:14Z")
> [@engineer\_comp\_geek](#): > > If you’ve got the new super duper whiz bang fancy shmancy digital meters, they usually can measure vars, and often they will report your power factor back to the power company. Unless your power factor is really far out of whack (like you are running a couple of 10,000 hp motors in your basement for some reason) It’s always those 10,000 hp motors that give you away. If you’re running a pair of 10,000 horsepower motors I’d think the electricity company would send you a complimentary ham at christmas and just add some caps to balance your out-of-whack power factor for you. Not just a cheap one either - a quality ham, hand reared by naked virgins on the finest corn. Edit: this assumes you pay your electricity bill! ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [June 18, 2010, 6:32pm UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106/62 "2010-06-18T18:32:22Z")
I’m amazed at how small paper capacitors are these days. Look at the wax ones in 1950’s radios. In the 1970’s I used a lot of the Sprague Orange drops. They were smaller. Today, paper capacitors are even smaller. A friend of mine restores and sells antique radios. I’m amazed at how component size has shrank. Well, except for the tubes. They are the same. ---
**Author:** ![The\_Scrivener](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@The\_Scrivener](https://boards.straightdope.com/u/The_Scrivener)\ **Post date:** [June 18, 2010, 6:32pm UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106/63 "2010-06-18T18:32:50Z")
> [@Tastes\_of\_Chocolate](#): > > I used to work in sales for a capacitor manufacturer. > It sounds like you’ve got an aluminum electrolitic cap there, based on the values you mention. > > Going up in voltage won’t be a problem, and it will to a small extent offset downgrading the temperature rating (in that a part rated for 35v won’t run as hot as one rated for 10v). More than space on the board, you need to be concerned with lead spacing. > > But I’d still be leery of downgrading the temp on that. A cap that is hot run will at the least drastically shorten the life of the capacitor. At worst, the cap may fail and vent, causing damage to the board it is on. > > I’d second the suggestion to check with Digikey, Mouser or Newark. > > Digikey has a search engine [http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=131081](http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=131081) > Enter your requirements and see what they have in stock. Thanks for the link, but I haven’t been able to successfully search the first two sites (I don’t have enough info to fill all their search fields – like tolerance and ESR or equivalent series resistance; and the manuf. seems to be Samsung/Sam Yeung, not listed, and the other codes like XC and VDA don’t appear on the lists either). User-friendly or ordinary-consumer-friendly, these sites ain’t! On to the Newark site, then… ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [June 18, 2010, 6:39pm UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106/64 "2010-06-18T18:39:22Z")
> [@aceplace57](#): > > I’m amazed at how small paper capacitors are these days. Look at the wax ones in 1950’s radios. In the 1970’s I used a lot of the Sprague Orange drops. They were smaller. > > Today, paper capacitors are even smaller. A friend of mine restores and sells antique radios. I’m amazed at how component size has shrank. Well, except for the tubes. They are the same. I don’t think anyone even makes paper capacitors anymore. Well, maybe there are a few still in production. Most non-electrolytic capacitors use either a plastic (Mylar, Polypro, Polyester, etc.) or ceramic as their dielectric. ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [June 18, 2010, 6:46pm UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106/65 "2010-06-18T18:46:59Z")
Those aren’t search fields you’re expected to fill in (unless you know) at Digikey, those are filters. What you do is select only the fields you’re interested in, then click the “apply filters” at the bottom. If this narrows the search enough, you’ll go directly to the first page of results. Or you’ll get a new (narrowed) set of fields. You can also start looking at the results, no matter how many, by clicking the ‘view page’ button. The ‘reset’ button will clear all the filters in case you want to back up. While it may not be perfect, Digikey actually has one of the better parts search sites around. As a hobbyist, you’ll also need to check the “in stock” checkbox, which will filter out results for items you can’t order and further reduce the number of results. (It’s a good idea anyway, regardless of whether you can special order). ---
**Author:** ![longPath](https://avatars.discourse-cdn.com/v4/letter/l/bb73d2/32.png) [@longPath](https://boards.straightdope.com/u/longPath)\ **Post date:** [June 18, 2010, 9:52pm UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106/66 "2010-06-18T21:52:46Z")
> [@The\_Scrivener](#): > > A question for you capacitor experts: I have a less-than-two-years-old Samsung HD TV with a blown capacitor (and a one-year warranty) of the following specs: > > Thanks in advance for your replies. Barely a day goes by that I don’t don’t repair at least one of these sets. We buy 1000 uf/16V and 2200 uf/16V (105c) capacitors 50-100 at a time to get the price break. There is one board where the bigger caps are a tight fit but no repeat failures that I know of. ---
**Author:** ![Tastes\_of\_Chocolate](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tastes_of_chocolate/32/3232_2.png) [@Tastes\_of\_Chocolate](https://boards.straightdope.com/u/Tastes_of_Chocolate)\ **Post date:** [June 19, 2010, 2:03am UTC](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106/67 "2010-06-19T02:03:14Z")
> [@The\_Scrivener](#): > > Thanks for the link, but I haven’t been able to successfully search the first two sites (I don’t have enough info to fill all their search fields – like tolerance and ESR or equivalent series resistance; and the manuf. seems to be Samsung/Sam Yeung, not listed, and the other codes like XC and VDA don’t appear on the lists either). User-friendly or ordinary-consumer-friendly, these sites ain’t! Most of those fields you can ignore. Is there an “M” or a “K” on the part someplace? “M” is 20% tolerance. “K” is 10%. There is a small chance you might see a “J” and that is 5%. It’s entirely possible that you won’t be able to find the exact manufacturer. Many of the big TV/phone/computer builders buy their parts from smaller companies. On the Digikey site, here is what I would use to filter: Aluminum capacitor pick the “in stock” check box up at the top capacitance 2200uf packaging “radial” temp “-40 +105º” and “-55 +105º” limit your voltage to 10v and higher from there, you need to measure what the lead spacing is on your current part. Most likely, it will be either 5mm or 7.5mm I know the Nichicon lines best. If I was doing what you are doing, I’d look at maybe the “PW” series. It’s a middle of the line high temp part. [Previous page](https://boards.straightdope.com/t/what-does-a-capacitor-do/536106.md?page=3)