Re: heating a cap

On a sunny day (Fri, 04 Oct 2024 22:15:50 -0700) it happened john larkin
<JL@gct.com> wrote in <8qi1gj5d27uqdkudv6vfql0fcv273mjcve@4ax.com>:

On Fri, 04 Oct 2024 23:50:36 +0100, Cursitor Doom <cd@notformail.com>
wrote:
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On Fri, 04 Oct 2024 10:31:13 -0700, john larkin <jl@glen--canyon.com>
wrote:
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On Fri, 04 Oct 2024 12:10:38 -0400, legg <legg@nospam.magma.ca> wrote:
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On Thu, 03 Oct 2024 16:36:24 -0700, john larkin <jl@glen--canyon.com>
wrote:
>

I got a small (under 1" long) aluminum electro cap, 220 uF 63v, and
cranked up the voltage. It started drawing a bunch of current at 105
volts, got hot, and folded back to 80 mA at 87v.
>
It got too hot to touch in a couple of minutes, after roughly 500
joules. Freeze spray let it go back up to 100 volts or so.
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None of that seemed to damage it, so an electrolytic cap sort of has a
built-in MOV.

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You're not 'heating a cap'.

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Felt hot to me.
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You're applying voltage overstress to failure, using a
current limited source.

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But it didn't fail.
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This tells you precisely nothing.

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Told me a lot. Why elect to not learn things?
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Were you earing safety glasses?

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No earrings, and my normal glasses.
>

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Are you sure you want to advertize this increasingly
erratic behavior?

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Experimenting with parts is admittedly a bizarre thing for an engineer
to do. Sorry.

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Legg seems to have a problem on the groups with anyone who isn't an
out-and-out Commie. Just ignore him.

>
There's no reason to not destroy parts. They don't have feelings.

How do you know, have you been once?

BTW I did test some parts out of spec..
But many problems come from aging with electrolytic caps.
My old Samsung TV lasted 20 years... on many hours a day.
So good electrolytics do exist.
Just designing a bit below maximum specs may help.