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On Fri, 20 Mar 2020 12:34:35 +0100, Jeroen Belleman
jeroen@nospam.please> wrote:
I measured ESR values for some small Ta capacitors many years
ago and these values are about what I found at the time. My
conclusion was that small Ta caps are pretty much useless.
Interesting. HP made widespread use of them in their boat-anchors of
25-40 years ago. I'd really like to compare them with their aloominum
electros' equivalent values, but my ESR meter becomes unreliable at
anything sub 1uF so the other tants I bought at the same time (0.22uF,
0.33uF and so forth) are beyond my ability to test. I just have to
assume they're fine because larger ones from the same supplier seem to
compare well with the values of those shown on the datasheets of known
good manufacturers.
On Fri, 20 Mar 2020 12:34:35 +0100, Jeroen Belleman
jeroen@nospam.please> wrote:
I measured ESR values for some small Ta capacitors many years
ago and these values are about what I found at the time. My
conclusion was that small Ta caps are pretty much useless.
Interesting. HP made widespread use of them in their boat-anchors of
25-40 years ago. I'd really like to compare them with their aloominum
electros' equivalent values, but my ESR meter becomes unreliable at
anything sub 1uF so the other tants I bought at the same time (0.22uF,
0.33uF and so forth) are beyond my ability to test.
On Friday, 20 March 2020 00:53:52 UTC, Winfield Hill wrote:
Gerhard Hoffmann wrote...
schrieb Cursitor Doom:
I took a crazy risk and got some axial Kemet tantalums ...
I have measured 400 mOhm ...
Perhaps your concern should be whether they will explode
or not. I used 10s of thousands of Kemet rectangular
axial-lead tantalums in oceanographic instruments my
company made in the 70s and 80s, without any incidents.
Keep them to at most 1/3 rated V and they should be fine.
NT
On Sun, 22 Mar 2020 12:08:34 -0700, jlarkin@highlandsniptechnology.com
wrote:
1/3 seems to work no matter what the rail can do.
That would take up way too much real estate. I have upped the voltage
rating on the replacements I've bought from 35V to 50V and even 60V
where there was no correct C value for 50V. Even going from 35 to 50,
which is not much over a third, and the axial leads have to be bent
back on themselves to fit the available space the 35s formerly
occupied. So 100V ones are out of the question I'm afraid!
Gentlemen,
I took a crazy risk and got some axial Kemet tantalums off Ebay
(purportedly genuine). These are visually identical to the originals
out of one of my HP boat anchors. And the ESR figures are better than
the equivalent new aluminium (aloominum if you're in the US)
electrolytics. But are these ESRs low enough to be the real thing?
Here's an example of the values I'm seeing:
3.3uF / 60V = 0.68 ohms
1uF / 60V = 1.1 ohms
2.2uF /50V = 0.62
Thanks,
CD
On Monday, 23 March 2020 00:37:06 UTC, Cursitor Doom wrote:
On Sun, 22 Mar 2020 12:08:34 -0700, jlarkin@highlandsniptechnology.com
wrote:
1/3 seems to work no matter what the rail can do.
That would take up way too much real estate. I have upped the voltage
rating on the replacements I've bought from 35V to 50V and even 60V
where there was no correct C value for 50V. Even going from 35 to 50,
which is not much over a third, and the axial leads have to be bent
back on themselves to fit the available space the 35s formerly
occupied. So 100V ones are out of the question I'm afraid!
heat treat them post soldering is another option.
NT
On Sun, 22 Mar 2020 12:08:34 -0700, jlarkin@highlandsniptechnology.com
wrote:
1/3 seems to work no matter what the rail can do.
That would take up way too much real estate. I have upped the voltage
rating on the replacements I've bought from 35V to 50V and even 60V
where there was no correct C value for 50V. Even going from 35 to 50,
which is not much over a third, and the axial leads have to be bent
back on themselves to fit the available space the 35s formerly
occupied. So 100V ones are out of the question I'm afraid!
On 2020-03-28 12:59, tabbypurr@gmail.com wrote:
On Monday, 23 March 2020 00:37:06 UTC, Cursitor Doom wrote:
On Sun, 22 Mar 2020 12:08:34 -0700, jlarkin@highlandsniptechnology.com
wrote:
1/3 seems to work no matter what the rail can do.
That would take up way too much real estate. I have upped the voltage
rating on the replacements I've bought from 35V to 50V and even 60V
where there was no correct C value for 50V. Even going from 35 to 50,
which is not much over a third, and the axial leads have to be bent
back on themselves to fit the available space the 35s formerly
occupied. So 100V ones are out of the question I'm afraid!
heat treat them post soldering is another option.
NT
Heat is what damages them. Re-forming them with a current-limited supply
is the ticket. See
https://electrooptical.net/SED/?page=2
On 2020-03-28 12:59, tabbypurr wrote:
On Monday, 23 March 2020 00:37:06 UTC, Cursitor Doom wrote:
On Sun, 22 Mar 2020 12:08:34 -0700, jlarkin@highlandsniptechnology.com
wrote:
1/3 seems to work no matter what the rail can do.
That would take up way too much real estate. I have upped the voltage
rating on the replacements I've bought from 35V to 50V and even 60V
where there was no correct C value for 50V. Even going from 35 to 50,
which is not much over a third, and the axial leads have to be bent
back on themselves to fit the available space the 35s formerly
occupied. So 100V ones are out of the question I'm afraid!
heat treat them post soldering is another option.
NT
Heat is what damages them. Re-forming them with a current-limited supply
is the ticket. See
https://electrooptical.net/SED/?page=2
Cheers
Phil Hobbs