Forums

Tantalum capacitor ESR

Started by Cursitor Doom March 19, 2020
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
Am 20.03.20 um 01:31 schrieb Cursitor Doom:
> 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
I have measured 400 mOhm for 4700 UF / 25V / AVX / wet tantalum bought from DK or Mouser. Kinda disappointing for > €100. But the leakage current was OK, that's what I really needed. Cheers, Gerhard
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. -- Thanks, - Win
On Thursday, March 19, 2020 at 8:53:52 PM UTC-4, 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.
I have a Kemet tantalum on the board I produce. The original contract assembler I used would automatically replace that part if the board didn't work. They never told me there was a problem. Seems some percentage of them would short or open or something. Later with another assembly house they had one scorch the board. I dug into that a bit (with some help here) and added a power on with a series resistor as the initial part of the test procedure. Too soon to know if that has helped the problem, but that is what has been recommended by a number of people. -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
On Fri, 20 Mar 2020 01:40:02 +0100, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

>Am 20.03.20 um 01:31 schrieb Cursitor Doom: >> 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 > >I have measured 400 mOhm for 4700 UF / 25V / AVX / wet tantalum >bought from DK or Mouser. >Kinda disappointing for > &#2013266048;100.
Do they still make those out of silver? -- John Larkin Highland Technology, Inc The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
On Thu, 19 Mar 2020 20:39:46 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Fri, 20 Mar 2020 01:40:02 +0100, Gerhard Hoffmann <dk4xp@arcor.de> >wrote: > >>Am 20.03.20 um 01:31 schrieb Cursitor Doom: >>> 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 >> >>I have measured 400 mOhm for 4700 UF / 25V / AVX / wet tantalum >>bought from DK or Mouser. >>Kinda disappointing for > &#2013266048;100. > >Do they still make those out of silver?
I think you're thinking about the hi-stability mica ones. And get back to bed, John, you need to strengthen your immune system right now.
On Fri, 20 Mar 2020 10:14:17 +0000, Cursitor Doom
<curd@notformail.com> wrote:

>On Thu, 19 Mar 2020 20:39:46 -0700, jlarkin@highlandsniptechnology.com >wrote: > >>On Fri, 20 Mar 2020 01:40:02 +0100, Gerhard Hoffmann <dk4xp@arcor.de> >>wrote: >> >>>Am 20.03.20 um 01:31 schrieb Cursitor Doom: >>>> 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 >>> >>>I have measured 400 mOhm for 4700 UF / 25V / AVX / wet tantalum >>>bought from DK or Mouser. >>>Kinda disappointing for > &#2013266048;100. >> >>Do they still make those out of silver? > >I think you're thinking about the hi-stability mica ones. And get back >to bed, John, you need to strengthen your immune system right now.
The CSR13-type wet tantalums had hermetrically sealed silver cases. They were great electrically, but eventually corroded and leaked from the chemicals inside. -- John Larkin Highland Technology, Inc The cork popped merrily, and Lord Peter rose to his feet. "Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
On 2020-03-20 11:14, Cursitor Doom wrote:
> On Thu, 19 Mar 2020 20:39:46 -0700, jlarkin@highlandsniptechnology.com > wrote: > >> On Fri, 20 Mar 2020 01:40:02 +0100, Gerhard Hoffmann <dk4xp@arcor.de> >> wrote: >> >>> Am 20.03.20 um 01:31 schrieb Cursitor Doom: >>>> 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
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. Jeroen Belleman
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 04:24:06 -0700, jlarkin@highlandsniptechnology.com
wrote:

>The CSR13-type wet tantalums had hermetrically sealed silver cases. >They were great electrically, but eventually corroded and leaked from >the chemicals inside.
These are the type I bought: https://i.pinimg.com/originals/10/ec/68/10ec686628e6233d117c956a1881d6c1.jpg Smaller capacity values, but *precisely* the same encapsulation. Now go back to bed.