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Modern caps use much better electrolytes than the caps from 30-40 years ago. They don't need the higher voltages to get good plate charge formation and they almost never need "conditioning" any more. Both those concepts are pretty outdated.
30 - 40 years ago? Are you trying to age me? If capacitors have advanced so far that these issues are no longer relevant, it didn't happen 30 - 40 years ago. What I wrote may be a little dated to the point it isn't as critical, but still worth considering.
No, just pointing out how long ago (and I would say considerably more than that) any such potential problems may have existed. I would suggest pre-60's, if not pre-50's - it's a LONG time ago, and of no relevance since.
I wasn't building amplifers in the 50's or 60's. I was running around in diapers. The relevance is much, much more recent. Some manufactures still publish guidance as to minumum voltage.
I suppose my experience with amp production points out the difference between "world class" products and the jellybean products others make.
You said you were told this by an older guy, I'm presuming he was basing this on experiences way back then? - or just on his imagination?.
I've built and repaired stuff since the 60's, professionally since 1971, never had any such problems, and never heard of any such problems.
The ONLY thing I have heard of, is 'reforming' main electrolytics in antique radios when they haven't been used for years and years. I've never seen or heard of any problems personally though, but it's been a long time since I played with old valve radios - and they may have not been unused for long enough.
Some manufactures still publish guidance as to minumum voltage.
Perhaps you could provide an example?, a previous poster has tried four different manufacturers and they don't - and no one else on these forums has heard of such a thing.
The "older guy" helped to found one of the most successful amplifier companies. He had decades of experience and was knowledgable of the most modern components. We took excruciating measures to build the very best products available. If the competition, or anyone else didn't, that was irrelevant. That's what made us "world class" and our customers understood the difference between us and the other guys. So anyway, this is where I cut my teeth in design, and I think what I learned is still relevant, though advances in component manufacturing might have lessened this as a critical issue. I'm willing to bet that designers at the company still carefully watch the minimum voltage on their electrolytics.
He checked a whole 4 manufactures. Wow! That must have taken all of 5 minutes!
Epcos has the following in their literature:
The DC voltage applied to the capacitor terminals must not exceed it's rated operating voltage, as this might increase the leakage current and may damage the capacitor. It is recommended to operate the capactor at 70 - 80% of it's rated voltage to optomize it's service life.
Also see ARRL recommendations posted above.
That you've never heard of any such thing leads me to believe my other experts on this issue. Looking at the data for the last couple days, it's apparent they were talking about "optomization" rather than just making something work. Still, it's an easy requirement for me to follow, so it only makes sense.
3.1.2 Operating voltage Vop
The capacitors can be operated continuously at full rated voltage (including superimposed AC voltage) within the entire operating temperature range. The permissible voltage range for continuous operation lies between the rated voltage and 0 V.
For short periods of time, the capacitors can also handle voltages up to -1.5 V (refer to chapter "General technical information, 3.1.6 Reverse voltage").
When the actual operating voltage is below the rated voltage, the operating leakage current is substantially lower:
The useful life can be prolonged by operating the capacitor at loads below the rating values (e.g. lower operating voltage, current or ambient temperature) and by appropriate cooling measures. In addition to the standard type series, EPCOS is able to offer types with useful life ratings specially matched to customer specifications.
It didn't contridict what I've been saying. You just didn't read far enough.
Also,
The company was created in 1999 from Siemens Matsushita Components, which was a joint venture of Siemens AG and Matsushita in 1989. The stock opened on 15 October 1999 at the same time in Frankfurt and New York, with Siemens and Matsushita holding interests of 12.5% each. In 2006 Siemens sold its shares of Epcos. In October 2006 Matsushita also sold its holdings. TDK Corporation agreed to acquire a controlling stake in the company on 31 July 2008.[1]
What's the relevence of the company details?, and why would I read that?.
As the quotes I posted were cut and pasted from their technical literature, it obviously completely contradicts what you've been saying - and I read to the end of it.
It obvoiusly does not contradict what I've been saying. I've said all along it's an optomazation. Newer literature from the company shows what I'm saying. https://www.epcos.com/inf/20/30/db/alu_x/B41161.pdf
The recommendations are a result of newer literature, not lead type.
I don't care what you read. Company is relavant becuase you asked for an example.
The technical data I quoted was more up-to-date, and gave a tighter recommendation for operating voltage. "Lower" is non-specific. How much lower??? etc.
No, the difference is updated literature. Lead type doesn't matter.
As far as I know the "minimum voltage" issue was from the days of the OLD electrolytics, those big ugly paper dielectric models (I'm sure Nigel remembers, as would the amplifier engineer of 30 years experience).
The paper (and some early plastic) dielectric was thick like cardboard and the caps were huge. Because of the thick dielectric they needed a high enough voltage to achieve a plate charge and start working like a capacitor, if the voltage was too low they were more like an open circuit (or a high ESR problem). So you had the need to "condition" them especially if they were high voltage ones like 400v ones in valve amps etc.
Modern electrolytics use incredibly thin dielectric films, that's why a 2200uF cap now is like your pinky finger and in the '70s it looked more like the size of an egg!
With the really thin dielectrics and good electrolyte they work great from even very low voltages. You could try measuring a 63v cap's capacitance at 1v and then at 63v, I really dont think you'd find much of a difference.
This I guess you should call up capacitor manufactures and educate them about their products. Some still think their caps work better within a voltage range.
This I guess you should call up capacitor manufactures and educate them about their products. Some still think their caps work better within a voltage range.
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