Panasonic EE series caps as PS filter caps?

[Gregg]

As a result, snap-in electros at about 350-450Vdc are GREAT in terms of size, price, function and life. I heavily recommend using them.

+1. The only reason to use axial caps is for restoration or mojo. Moreover I radial caps are available in 105C and longer life versions unlike most axial caps.

[R.G.]

Does the magnitude of the DC leakage affect the performance of caps as power supply filters? The rated DC leakage seem to vary from a few hundred uA to a few mA. I guess I wonder if this characteristic is important.

Almost certainly not. I only say "almost" because a few ma seems big to me. Let's think: 400V * 1ma is 0.4W, and about the plate current of half a 12AX7. Not a biggie at all. I think a few ma is most unlikely in new or non-damaged caps. The leakage will be unnoticeable as an issue on a power supply of a few tens of watts.

But this does illustrate the huge range of DC leakage point. If you have two 100uF/350V caps in series to run a 500V power supply, and one has 100uA leakage while the other has 400uA leakage, the one with the high leakage will settle down to only 100V and the 100uA leakage one will settle down to ... oops... 400Vdc out of the 500. You can blow one of the two "identical caps.

No, wait. If one of the two shorts, then the other cap is carrying the whole 500V and it dies too. 8-|

[schoolie]

Thanks, R.G.! The Panasonic datasheet for the EEU-EE2V101 states 0.06CV+ 10uA. Their TS-ED cap has a much better leakage of 3*sqrt(C*V). The F&Ts have a rated leakage of 0.008CV + 6uA. I guess it would make sense to match the series caps by value and leakage, or be very conservative with the working voltage rating.

I've heard a rule of thumb that two caps with a rated voltage V should only handle a working voltage of around 5/3*V, when used in series.

[R.G.]

Always be aware that the maker is not telling you how to calculate an accurate number with those figures. They're just telling that this is a maximum; it may be much better than that estimate. The estimate formula is (probably) arrived at by estimates based on square inches of aluminum oxide on their main process line, with X% of the nominal voltage applied, at room (or max) temperature when measured by a right handed technician who is carrying on a committed relationship with an Icelandic virgin. (!?)

Never, ever trust a datasheet number given as a single ended max or min, or "typical".

[tedmich]

The CDE guide is quite useful
http://www.cde.com/catalogs/AEappGUIDE.pdf
including real math for equalizing resistors (usually a bit lower than 220k default)

[schoolie]

Actually, it didn't work out with the Icelandic virgin. She wanted kids, he wanted to test passive components. Sad, Really

Thanks for the great advice! I guess I have to buy samples and test them myself.

[Chuck H]

Update with interesting news...

I installed the new Nichicon cap as the first power supply filter of an amp I built about two years ago using Atom's. The amp had some problems with ripple that weren't consistent with other virtually identical amps I've made. So... The new cap solved any problems (at about one third the price and one third the size of the Atom). Tossing the old cap aside as I prepared to install the new one I heard a tiny rattle. So I picked up the cap and shook it. There was something inside the can tinking around. After I finished the job I took the old cap home and sawed the top off. Inside was the typical much smaller cap in a big can thing that Atoms are already known for. But also A LOT of crystaline crust around the cap "plug" and more powder and larger flakes inside the outer can. I have to assume this was crystalized electrolyte and aluminum oxide that oozed out of the cap plug. The Atom cap was purchased new from Mouser and used immediately. Again, about two years ago. Whether this is Spragues fault for selling an old cap, Mousers fault for selling an old cap, my fault for not "charging" new caps (which I never have), or some QC or electrolyte formula failure I can't say. I can say that I'm having similar issues in another amp that isn't quite four years old that was built with the same caps (presumebly from a different batch since they were purchased over a year before). I can also say that I won't be buying any more Atom caps.

[Tom Phillips]

It's interesting how faithful some people have been to the Sprague Atom line. Especially after the rattle problem started showing up several years ago. that problem was eviddence that the internal construction of the Atom caps was no longer the same as the legacy product. Therefore, any mojo associated with the legacy design was gone. One thing I do like is the sturdy and long leads. I'm actually surprised that the line is still in production. I believe they have been on the "not recommended for new designs" list since the mid '90s or earlier. I imagine that they just kept making them because of the prices people were willing to pay.
Tom

[riz]

+1 on Nichicon PW series. Just fired up a tube mic power supply I made with them. I noticed they seem to weigh more than the VX series Nichicons I have been buying locally (ordered the PWs from Mouser). I am officially a fan!

[R.G.]

It's interesting how faithful some people have been to the Sprague Atom line. ... I believe they have been on the "not recommended for new designs" list since the mid '90s or earlier. I imagine that they just kept making them because of the prices people were willing to pay.

In management parlance, the Atom cap line is a "cash cow". It will continue to sell for good prices even with no new investment. It is likely that Sprague decided to not make it unavailable, but instead subcontracted its manufacture to someone else so it continues to sell, makes good profit, and doesn't even require space or maintenance on the production line - well, that is if Sprague still makes caps at all instead of subcontracting 100% of its products to a cheaper vendor. It's possible that this last is just a bad dream, but unfortunately, it's a plausible one.

Even then, that's not as bad as the counterfeit market. I've seen pictures of caps which yield ... another, smaller cap inside when cut open. The smaller cap is from a - um - lesser known name manufacturer.

[diagrammatiks]

I think Vishay has said that they would love to stop making the Atoms.

At this point I think they've actually stopped making the actual capacitors and all that's running is the one machine that makes the casing.

In management parlance, the Atom cap line is a "cash cow". It will continue to sell for good prices even with no new investment. It is likely that Sprague decided to not make it unavailable, but instead subcontracted its manufacture to someone else so it continues to sell, makes good profit, and doesn't even require space or maintenance on the production line - well, that is if Sprague still makes caps at all instead of subcontracting 100% of its products to a cheaper vendor. It's possible that this last is just a bad dream, but unfortunately, it's a plausible one.

Even then, that's not as bad as the counterfeit market. I've seen pictures of caps which yield ... another, smaller cap inside when cut open. The smaller cap is from a - um - lesser known name manufacturer.

There is no Sprague anymore.

[Chuck H]

I must admit that I used them for the last four amps I built just because I had always used them before with good results. They were more reasonably priced too when I started using them. More like thirty percent more expensive. Not three times the price like they are now. I don't doubt that the cap plug inside the cans is made by some outside source. So why not use something good? If I can get superior quality caps for one third the price at retail wouldn't it still be a profit for them buying good plugs at wholesale for repackaging? Then they could even publish specs for their product. Something that is notably lacking right now. people would go right on buying them and loving them. Happy for the axial leads, the look and happily pay more in the belief that they're getting a cap with good performance and a good rep. Never knowing any better and never caring at all. You could perpetuate something like that forever as long as you didn't do something STUPID like soil your rep by stuffing a $h!tty cap into your expensive can and then skirt published specs. I expect it's because Sprague doesn't even repackage them. They probably have their overseas supplier do it. And as such they can't get a decent cap manufacturer to agree to that sort of thing.

[diagrammatiks]

I don't think Vishay cares about that line anymore.
All of the properties they brought from Sprague have absolutely stone age specs. The lifetime rating for the TVA isn't even listed anymore.

Their BC acquisitions are better in every single way.

[Tom Phillips]

Anyone know what's up with the caps marked "United Chemicon" that otherwise look just like the bodern blue Atom line. I have not seen any new ones offered for a few years but I always considered that United Chemicon may have been the actual manufacturer of the modern Atom line.

[diagrammatiks]

as far as I know, united chemicon, nippon chemi-con, rubycon, and one other company are all the same...

but I haven't been able to verify that myself yet.