Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shooter on December 12, 2015, 09:46:15 am
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I have boxes full of old computer grade caps, typical would be up to 50,000uF @50vdc
I’ve been toying with the idea of making a "catastrophic cap failure power supply". :icon_biggrin:
Say 450vdc at 300mA for “testing” the computer caps. My question, is the voltage differential the critical factor in failure testing or is current just as important?
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I’ve been toying with the idea of making a "catastrophic cap failure power supply".
Please tell me more! And why?
Plugging a 50V electrolytic into the wall socket will probably do a good job. :icon_biggrin:
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Please tell me more! And why?
The more; ideally an "unplugged" DC power supply charging, think BIG CAP bank with 400-500vdc, big remote controlled switch, little(vdc) cap under test.
The why; hmmmm, call it a proof of concept build, exploring the "merits" in accelerating gases/heat in various confined spaces :icon_biggrin:
my unknowns;
1 is voltage differential the biggest factor in failure, or does current play a big role.
2. Is failure "easier" if the test cap is wired backward.
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1 is voltage differential the biggest factor in failure, or does current play a big role.
I've only popped one cap, and that was with almost zero current. But by Gawd, you exceed the voltage rating by about 50% cuz you weren't paying attention, and thar it blows.
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When you get over 2X rated voltage, the current will get VERY high.
I suspect your 300mA supply will fail before you can blow-up a soup-can cap.
At best it will simmer slowly, not BURST.
Wall outlet should break-down 50V e-caps, but again the current may overload things (which could mean wall-fire). I'd advise wiring a 1,000W toaster or heater in series so the worst-case current isn't dangerous to the wall wiring.
You ARE aware that bursting caps, especially large caps, IS dangerous? And messy? I'd try it at the far end of a 50-foot extension cord down the driveway.
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You ARE aware that bursting caps, especially large caps, IS dangerous? ...
I was thinking this earlier, then the phrase "natural selection" came to mind. :l2:
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:laugh:
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proof of concept build, exploring the "merits" in accelerating gases/heat in various confined spaces
Use a number of the caps in series in a voltage doubler circuit and fire the circuit with a Triac? through a pulse shaping network into a water filled glass ampoule with small gauge wire inside. Alternatively you could electrolyse the water in the ampoule and use a spark discharge instead of the wire. Those caps are probably too big to gasify at those voltages and at 120 watts would likely look more like a party popper.
I'm guessing you want to advance the science of mechanically digesting kidney stones in a water bath. The problem that arises though, if there is one, compared to chemically based kinetic systems this would be a large cumbersome solution. Compare your capacitor based system to say the Hitachi gas based Ram Set used to drive nails in the construction industry.
silverfox.
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then the phrase "natural selection" came to mind
:l2:
I have made it 59yrs so far doing "fertile mind" experimenting. :icon_biggrin:
I am *safety conscience* my 35yr career mandates that, 5,000 to 144,000vdc WILL kill you quick if you're not on your game!
Thanks PRR, I figured it would take current, lots, I just wasn't sure since cap rating I've looked at never really
*emphasize* that like other components.
this would be a large cumbersome solution
I think you're right silverfox,
If *it* goes anywhere i'll post my findings
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> I figured it would take current, lots, I just wasn't sure since cap rating I've looked at never really *emphasize* that like other components.
Well, they do tell you a limit voltage. Anything past that is *your* problem.
Expecting (hoping-for) overload details like that is like overload info on a water-heater. They say it is good for 50psi, and they leave a margin of safety. But they are not likely to answer "if I pump/heat it to 500psi, how high will it fly?" That information is out there; MythBusters blew/flew a few water heaters, and I am sure it is a popular pastime on YouTube. Likewise you can probably find cap-explosion videos online. But you aint supposed to do that, and the makers are not eager to tell you what could go wrong.
It's a can of electrolyte. Steady current flow is blocked by a micro-thin layer of oxide. If you break that down, it becomes a can of soup with large electrodes. I would expect a large can of highly salted soup to flow a LOT of current; I would think that for low ESR the cap-electrolyte is at least as conductive as salty soup.
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MythBusters blew/flew a few water heaters
That was fun to watch :icon_biggrin:
I would expect a large can of highly salted soup to flow a LOT of current
Thanks again, I have replaced - cleaned up splattered caps, I just didn't take the time to *understand* the actual process, since I was paid well to fix it, then move on to the next *fire* But this site, gets me to use my gray n white matter at a deeper level then fix it n forget it