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100 Caps for a Buck — Parallax Forums

100 Caps for a Buck

ercoerco Posts: 20,256
edited 2015-02-06 10:33 in General Discussion
OK, $1.25 but they are electrolytics! At 1.25 cents each, who would even bother faking that many?

100x 10uF, 25VDC. I'll use them for 5VDC filter caps, so even if they are seconds and the ratings are off 50%, who cares?

http://www.ebay.com/itm/171610924827

Comments

  • User NameUser Name Posts: 1,451
    edited 2015-01-21 16:10
    Hey, they'd be a great complement to a large supply of LD1117 regulators sitting on the shelf. For $1.25 I'll gladly take a chance. Thanks!
  • zappmanzappman Posts: 418
    edited 2015-01-21 16:30
    erco wrote: »
    OK, $1.25 but they are electrolytics! At 1.25 cents each, who would even bother faking that many?

    100x 10uF, 25VDC. I'll use them for 5VDC filter caps, so even if they are seconds and the ratings are off 50%, who cares?

    http://www.ebay.com/itm/171610924827

    Beware of cheap electrolytic caps.
    Years ago the formula for the electrolyte used in electrolytic caps was stolen.
    But, the thief only got 1/2 the formula.
    Many Asian companies used the stolen formula to make capacitors, but their capacitors would fail prematurely.
    The bad capacitors found their way into all kinds of name brand consumer electronics, such as PC's, TV's and Monitors.

    http://whatreallyhappened.com/WRHARTICLES/badcaps.html
    http://en.wikipedia.org/wiki/Capacitor_plague
    http://www.badcaps.net/
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2015-01-21 16:50
    erco wrote: »
    OK, $1.25 but they are electrolytics! At 1.25 cents each, who would even bother faking that many?

    100x 10uF, 25VDC. I'll use them for 5VDC filter caps, so even if they are seconds and the ratings are off 50%, who cares?

    http://www.ebay.com/itm/171610924827

    Premature ageing and failure is the problem and I'd rather spend 10 cents on this cap and make sure. I know this goes against the erco grain, spending 9 cents more when 1 will do :)

    BTW, @Zappman, interesting read on the cap plague which is something I've always been aware of but didn't know it was "official". I've had so many PVRs and monitors etc fail fail fail because of this and some I even bothered to repair. Even $exchange$ ECMs have been good business for some who only have to replace an electrolytic on the faulty units then recycle them back as $exchange$ ECMs!
  • User NameUser Name Posts: 1,451
    edited 2015-01-21 20:07
    Operating conditions for electrolytic caps vary widely. Heat in particular leads to early demise even of quality capacitors. Illinois Capacitor provides this little bit of wisdom:

    The operating conditions directly affect the life of an aluminum electolytic capacitor. The ambient temperature has the largest effect on life. The relationship between life and temperature follows a chemical reaction formula called Arrhenius' Law of Chemical Activity. The law put simply says that life of a capacitor doubles for every 10 degree Celsius decrease in temperature.

    So even if the caps in this offer are filled with a wonky electrolyte, I'll bet they'll work great attached to an LD1117 and sitting in a 20C office. But I also heard a few months ago that Chinese manufacturers were purchasing electrolyte from Japan. So these may not be wonky. Either way, seems pretty interesting to me.

    It goes without saying that no one should be decoupling their core i7 with these. :)
  • ercoerco Posts: 20,256
    edited 2015-01-21 20:55
    Prolly still good for pyrotechnics. :)
  • CuriousOneCuriousOne Posts: 931
    edited 2015-01-22 00:00
    Almost same price per capacitor, but capacitors are genuine Panasonic, high quality ones:

    http://www.ebay.com/itm/1000-X-Panasonic-ECE-V1EA330SP-CAP-33UF-20-25V-AL-CASE-D-SMD-/230740699092?pt=LH_DefaultDomain_0&hash=item35b937a7d4
  • GadgetmanGadgetman Posts: 2,436
    edited 2015-01-22 00:27
    Actually, that's a lower price...
    $6.50 for 1000 instead of $1.25 for 100...
    (Well, shipping sucks on the Panasonics, the no-named doesn't ship to Norway. Guess which I bought... )
  • CuriousOneCuriousOne Posts: 931
    edited 2015-01-22 01:09
    And the seller of Panasonics has other goodies to, and he adjusts shipping. I've bought several lots of capacitors and other parts from he, he added couple of extra lots as gift.

    These Panasonics have long leads, so they can be straightened and even used on breadboard or thru-hole designs.
  • wmosscropwmosscrop Posts: 409
    edited 2015-01-22 06:44
    Gadgetman wrote: »
    (Well, shipping sucks on the Panasonics, the no-named doesn't ship to Norway. Guess which I bought... )

    Ironically, I live just a few miles away from the seller... but no local pickup. Ah well.

    Walter
  • RDL2004RDL2004 Posts: 2,554
    edited 2015-01-22 08:42
    These are what I use. Yeah, they cost over 10x as much, but we're talking pennies here. I prefer to know that they probably meet the specs and will last a while. Oh, and they're not SMD, still pretty small though.

    http://www.mouser.com/ProductDetail/Nichicon/UPW1C100MDD/?qs=sGAEpiMZZMtZ1n0r9vR22UwyiKSDS%252bfFV%2f%252bROJNL1dU%3d
  • tonyp12tonyp12 Posts: 1,951
    edited 2015-01-22 11:50
    many ELECTROLYTIC are only rated for 2000 or 4000 hrs, would not last a year if on most of the time

    If you only need 10uF 16V:

    4cents for Ceramic 1K order
    http://www.mouser.com/ProductDetail/Murata-Electronics/GRM21BC81C106KE15L/?qs=sGAEpiMZZMs0AnBnWHyRQKFZIQ7b73cdGHxNihrk%2fykL%2fs1exAwMsg%3d%3d

    11cents for Tantalum at 1K order
    http://www.mouser.com/ProductDetail/AVX/F931C106KAA/?qs=sGAEpiMZZMsh%252b1woXyUXjx8BsXRNKjx1adrZjqUlTRY%3d

    I would rather double up on Ceramic until I need to be above 50uF, then go Tantalum until I need to be above 400uF
  • CuriousOneCuriousOne Posts: 931
    edited 2015-01-22 21:47
    Not correct.

    They are rated at specified amount of time only at top working temperature. For the lower temperature, there is no such rating. I've seen electrolyes made 50-60 years ago, that still run OK.

    For the actual runtime for specific capacitor in specific conditions, Cornel Doubilier has very nice calculator on their website.
  • ercoerco Posts: 20,256
    edited 2015-01-23 13:48
    CuriousOne wrote: »
    Almost same price per capacitor, but capacitors are genuine Panasonic, high quality ones:

    Dang it, now I have a bunch of those too. 1900 to be precise. I bought a batch of 1000 for $5.50 (best offer) then the seller emailed that he had 900 left and would I want them for $4.50. Tempting a hoarder...

    So what's a fellow to do with 2000 capacitors? Build some sort of analog RC computer? Filter the Smile out of every project from now on?

    Duane Degn will inherit these when I die. Buried under an avalanche of capacitors in a minor earthquake.
  • GadgetmanGadgetman Posts: 2,436
    edited 2015-01-24 04:51
    Connect them in parallell, then feed it 230V AC...

    ;-)
  • localrogerlocalroger Posts: 3,451
    edited 2015-01-24 07:55
    Make a 230 byte dynamic RAM for your relay computer.
  • ercoerco Posts: 20,256
    edited 2015-01-24 10:09
    @localroger: We need a hoarders swap sub-forum. Collectively, we have everything imaginable in our respective inventories. You have too many relays, I have too many capacitors (and 339 comparators and TIP31 transistors and lasers and laser sensors and beepers and LEDs and...) etc. Let's create our own currency like bitcoins (partcoins?) and post what we have and need to swap.

    That started out as a joke, but it's actually not a bad idea.
  • User NameUser Name Posts: 1,451
    edited 2015-02-05 12:06
    They all report on the low side of 10 μF (no surprise there) but they all work perfectly well for my present uses. I'm very glad to have them! Should a seriously demanding application arise, I'll be sure to purchase a better capacitor.
  • ercoerco Posts: 20,256
    edited 2015-02-05 19:03
    The one I used yesterday tested at 10.7 mikes. Nice tiny caps. That's it just right of the IC.

    attachment.php?attachmentid=113074&d=1423191979
    tilt.jpg
    740 x 370 - 31K
  • Bob Lawrence (VE1RLL)Bob Lawrence (VE1RLL) Posts: 1,720
    edited 2015-02-06 10:33
    Re: 100 Caps for a Buck

    They would be handy for making buck converter's LOL

    I usually test caps before I use them and once in a while I find a bad one. Physically they look great , new etc.
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