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Rubycon RX-11 capacitors

Discussion in 'Electronic Design' started by Sergey Kubushyn, Aug 14, 2012.

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  1. Does anybody know what it is? There is no data anywhere, it looks like such
    thing doesn't exist.

    However I have a box (250pcs) of those, 25V 220uF. They are quite big,
    12.2mm diameter and 25mm high. Everything look pretty genuine. Black
    sleeves, clearly marked Rubycon RX-11. All writing is of very good quality,
    italic kinda handwritten 'Rubycon', '25v220uF' with real 'mu', not 'u'. They
    have _POSITIVE_ terminals marked with lines and circled '+' signs.

    It wouldn't have been worth asking if they have not been _THAT_ good.

    All of them have at least 250uF capacitance and ESR is under 70mOhms (zic!
    under SEVENTY MILLIOHMS) that is really impressive for an aluminum 220uF
    capacitor. This is roughly the same parameters OsCons have but those are
    aluminum polymer so they are special.

    Is it some Rubycon experiment with polymers? They have 2007 date code.

    It can NOT be fake because they have excellent parameters far exceeding any
    other aluminum 220uF capacitor. They are objectively better than anything
    else and there is absolutely no data on those :(

    Aha, there is NO temperature rating on them. Just 'Rubycon 25v220uF RX-11',
    line of '07 07 07...' and those '+' marks for positive terminal (that is
    longer than negative as it is supposed to be.)

    I bought that box from Ebay couple of years ago, don't remember who was the
    seller. Pretty sure they were dirt cheap because I wouldn't have bought a
    box of those otherwise. They were gathering dust all that time until I
    decided to recap one of my Tek 2465BDV scopes and found them on a shelf.
    Didn't find any info so reached for my HP 4274A LCR meter and was stunned by
    the result.

    Not that I do really need a datasheet on those, just out of curiosity. I do
    know they are outstanding capacitors far exceeding all those 'Ultra-Low ESR'
  2. legg

    legg Guest

    This may be an issue. Rubycon RX series numbers don't use a dash, and
    all larger RX jacketed parts have their temperature index, right after
    the series designator. 150deg parts don't have jackets, but are
    laminated over the markings.

    Rubycon uses the SE Asian marking custom of emphasizing the negative
    terminal on the sleeve art. Lead length coding is normal.

    A 12.5 x25mm case, even for 130 and 150 degree rated RX parts, will
    typically provide a capacitance of 4x this part, in the same volume.
    You'd expect to find an RX part of this size, capacitance and ESR to
    be sporting a 50V rating.

  3. That's what puzzles me. It DOES have a dash in RX-11, no temperature index,
    and it has its POSITIVE terminal marked. _ALL_ known aluminum capacitors
    have _NEGATIVE_ terminal marked.

    I know one place, former Soviet Union, where they used to mark positive
    terminals on aluminum capacitors (and they used to put a mark at diodes
    ANODE instead of cathode) but it has nothing to do with Rubycon...

    And those don't look like crappy chinese counterfeits -- it is very good to
    have under 70 mOhms ESR for 220uF electrolytic and it should have quite a
    high ripple rating judging from its size...
  4. Might be. I did not use many of those so I must've forgotten what they used.
    Aha, I see Spragues have plusses on them :)

    I started my EE career in Soviet Union so I still remember that mark was
    going to everything that is "PLUS" :)
    It looks like it. I don't care about sales, those are for internal use. I'm
    replacing a bunch of Sprague 672D 220uF 25V capacitors and those RX-11 seem
    to be even better than 672Ds. I don't know what their rated longevity or
    temperature rating that is why I asked.
    Sure. The bigger the can the more beating it can endure :)
  5. legg

    legg Guest

    Actually, some European and NA mfrs prefered exagerated + markings on
    their bodies (Philips, Siemens, Roederstien, Mallory Sprague) as a
    natural extension of the original axial can crimp-seal polarity ID.

    Not so much mfring there any more - whole factories moved across
    borders or off-shore, but internal standards ~preserved, at least on
    legacy product. Perhaps this is a subcontracted variation or early
    prorotype. I doubt either will be easily absorbed in after-market

    A switch to - term ID is forced to compete with highly competative
    commodities in a mostly manual assembly use market. I still see
    documentation-persistent errors, causing Philips parts to be inserted
    backwards, and vice-versa.
    Given similar ESR, the ripple current increases with case size or
    surface area, as this is a straight dissipation capability. ( ~
    1degree rise for every milliwatt disipated from 1cm^2 surface area ).
    Not a direct relationship, because power is I^2xR.
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