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Low Impedance Electrolytic Capacitors in Power Supply: Advantages? Disadvantages?

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  • #16
    The Atom's have been around for a long time. I don't know if the construction of them has changed. I do know that it's only in the last decade that people report the "tiny cap in a big can" thing. I vaguely recall someone cutting open an old one and a new one and they were indeed different. I mention this because, like many tubes made today, it's possible the "specs" for the Atom caps is grandfathered in, but is actually a spec for the older design.?. Just "spec"ulating (yuk yuk)

    Regardless of that... The lack of a life spec is something I always found suspicious. I mean, if you fail to promise the product will last then it's pretty easy to bump a spec idn't it? Also, the 85* temp rating. As mentioned, this will have an affect on that ripple current spec. The Nichicon is rated at 105*. I wonder how the Atom would spec at 105* in it's 7000th hour

    Nichicon is a very good product. I stopped using Atom caps and Orange Drops because of their stupid high price. I mean, those products do have a little bit of celebrity draw, but at some point you gotta say "That's enough gouging, get the "F" outta here." That, and I was occasionally getting Atom's that would under perform when new or soon after installation. Some would "burn in" and be ok, others wouldn't. So I've been using the Nichicon PW's for about six years. And guess what.?. No more new amps humming like they don't know the words or making sum/difference notes like a ring modulator. Now, I'm not a repair tech or an amp company. I only build a few amps for people that ask me to. But I've used the Nichicon PW's in three new products and three repairs (one recap was an older amp I built sixteen years ago with Atom's) and I spec'd them for a design I worked on with a major manufacturer. So, for whatever my part is, I'll endorse the Nichicon PW's.
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #17
      Originally posted by Chuck H View Post
      The Atom's have been around for a long time. I don't know if the construction of them has changed. I do know that it's only in the last decade that people report the "tiny cap in a big can" thing. I vaguely recall someone cutting open an old one and a new one and they were indeed different. I mention this because, like many tubes made today, it's possible the "specs" for the Atom caps is grandfathered in, but is actually a spec for the older design.?. Just "spec"ulating (yuk yuk)


      One of many in a 2013 thread over at our friendly neighbors The Amp Garage.

      http://ampgarage.com/forum/viewtopic...5d2794a244456e

      In case you decide to have a look & encounter any blarney from Google - "caution malware site" like that, just push past the well meaning guards & peep all you want, there's no malware. Someday TAG will get this fixed...

      Lately I've been experimenting with film caps for hi voltage power supplies. Lifetime factor just about forever. Pain is rectangular form factor, sometimes takes ingenuity (I hope I have) to fit securely. Full price, many compete with Sprague Atoms cost, and sometimes you can find films on close-out sale deeply discounted. I got about 35 x 30 uF 800 & 900V less than $5 each from Newark. So cheap my Scottish genes are dancing the highland fling. Happy hunting, & don't get shocked.
      This isn't the future I signed up for.

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      • #18
        Originally posted by Leo_Gnardo View Post
        my Scottish genes are dancing the highland fling. Happy hunting, & don't get shocked.
        Well, I can't promise anything. Is the highland fling shocking?
        "Take two placebos, works twice as well." Enzo

        "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

        "If you're not interested in opinions and the experience of others, why even start a thread?
        You can't just expect consent." Helmholtz

        Comment


        • #19
          Originally posted by Chuck H View Post
          Is the highland fling shocking?
          Only if it's dry & cold, and you wear a polyester kilt and no underclothes. HOOOOT MON! Ai-yi-yi caramba!
          This isn't the future I signed up for.

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          • #20
            The PW datasheet indicates 350mArms 120Hz ripple at 105C for 100uF 450V, if that provides some comparison to an Atom part.

            Some other aspects are that a 105C speced cap (such as the PW) would have a higher ripple current capability at 85C, as it could cope with the internal temp rise.

            The life hrs rating and temp rating are the main indicator of service lifetime, where arrhenius type improvements kick in for a normal amp not operating anywhere near the ripple and temp spec conditions.

            If you are keen, then using PSUD2 would quickly indicate the likely rms current experienced by the cap.

            For your use, the low impedance doesn't mean anything really. That moniker is related to the part having specs at 100kHz, to provide a smps designer with some assurance of the impedance at such a high frequency - although the datasheet doesn't actually show any generic impedance curve plots :-(

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            • #21
              +1 on the film caps if you really want to drive your vintage-correct buddies up the wall. I'm strongly considering going that direction once I've used up my current stock of electrolytics.

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              • #22
                Originally posted by trobbins View Post
                ... a 105C speced cap (such as the PW) would have a higher ripple current capability at 85C, as it could cope with the internal temp rise.

                The life hrs rating and temp rating are the main indicator of service lifetime...
                For your use, the low impedance doesn't mean anything really.... :-(
                Very helpful, TRobbins.

                Film caps look interesting — but I'm thinking I'll go with the Polyester Kilt type.

                Reminds me of my old friend Glenn's father, Alex who was fond of saying, "Yah, lad. Just watch yerself, baby-oh, or I'll piss up yer Kilt!"

                Thanks to all who chimed in!

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                • #23
                  Radial new production caps are the way to go. Forget about those huge crappy axial caps.
                  Speaking of Nichicon which are one of the best you can get some of them with 10 thousand hours guaranteed and that is at 105 degrees (Celsius of course).

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                  • #24
                    We did.

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                    • #25
                      Originally posted by Gregg View Post
                      Radial new production caps are the way to go. Forget about those huge crappy axial caps.
                      Speaking of Nichicon which are one of the best you can get some of them with 10 thousand hours guaranteed and that is at 105 degrees (Celsius of course).
                      Perhaps we should start encouraging the use of radial-leaded power resistors too. I hate the look of big axial-leaded power resistors wired to eyelets or turrets that are too close together for elegant placement.

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                      • #26
                        Perhaps we should start encouraging the use of radial-leaded power resistors too.
                        This is not a bad idea. I've seen them in Marshalls and other amps.

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                        • #27
                          Hey! Slow up now... What about us guys that don't build PCB? I only use radial caps as a concession. Because the good and affordable caps are all radial now. I don't want to kludge a method for radial resistors too.
                          "Take two placebos, works twice as well." Enzo

                          "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                          "If you're not interested in opinions and the experience of others, why even start a thread?
                          You can't just expect consent." Helmholtz

                          Comment


                          • #28
                            In some old juke boxes the electrolytics weren't just can-caps, but had pins coming out the bottom which fitted into octal tube sockets. That way the service engineer could try swapping the caps instantly, if the thing was buzzing or humming!

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                            • #29
                              Originally posted by Malcolm Irving View Post
                              In some old juke boxes the electrolytics weren't just can-caps, but had pins coming out the bottom which fitted into octal tube sockets. That way the service engineer could try swapping the caps instantly, if the thing was buzzing or humming!

                              like this?

                              Click image for larger version

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                              relays too

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                              • #30
                                Let's bring those back! We could be cap-rolling as well as tube-rolling!

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