Tantalum capacitor ESR

Am 20.03.20 um 01:31 schrieb Cursitor Doom:

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

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

I have a Kemet tantalum on the board I produce. The original contract asse mbler 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 w ould short or open or something. Later with another assembly house they ha d one scorch the board. I dug into that a bit (with some help here) and ad ded a power on with a series resistor as the initial part of the test proce dure. Too soon to know if that has helped the problem, but that is what ha s been recommended by a number of people.

--

  Rick C. 

  - Get 1,000 miles of free Supercharging 
  - Tesla referral code - https://ts.la/richard11209

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"

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"

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

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.

These are the type I bought:

Smaller capacity values, but *precisely* the same encapsulation.

Now go back to bed.

That looks like the classic silver-can wet-slug tantalum. Some later models had a tantalum case. Silver dollars used to be silver too.

The problem with this idiotic lockdown is that all days seem the same when you don't go to work. So we forgot that we have to put the trash out on Thursday night. We heard the truck outside about 4AM. I had to open the garage, grab the black and green wheelie bins, and chase the truck down the block in my socks. He (or maybe she?) was really nice and we had a little talk about the general situation. But that woke us up pretty good.

Steering one wheelie bin at walking pace isn't bad. Running with two is dynamically unstable.

Retirement must feel like this. All days the same, no reason to go to bed or get up at any particular time, not much to do.

--

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"

Intermediate values of ESR are basically what tants have to offer. That's why we didn't have problems with voltage regulators oscillating back before huge ceramics and alpos were available.

Those values might even be on the low side for a small cap like that.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

Lots of linear regulators are super stable with one big tantalum and a bunch of ceramics on their output.

--

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"

For many people, working in cubicle land can be like that too :(

Don't bet on it; many people wonder how they managed to do things before retirement!

The main difference is that there is less pressure

That's *exactly* how it feels. And weekends lose much of their significance, too. That's why after 2 years of "exquisite pregnant idleness" I decided to go back to some form of work. Didn't need the money; just had enough of tumbling helplessly through time with no reference points to mark the passage towards the grave.

Reminds me of an episode of Downton Abbey where the men are discussing some business matter at a meal and mention it can be done on the weekend. Maggie Smith playing Violet Crawley, the Dowager Countess of Grantham, says, "What is a week end?"

I suggest you take up some hobby such as kayaking.

--

  Rick C. 

  + Get 1,000 miles of free Supercharging 
  + Tesla referral code - https://ts.la/richard11209

Gerhard's hecto-buck wet tants have a much lower risk of exploding than the far more common sintered solid construction that react badly to surge currents.

piglet

You can't tell by just looking because they put the solid type inside those hermetic glass-metal-seal cases too. Part number (and price) will distinguish better :)

piglet

A weekend is still significant because when you go places, they're full of kids and their parents.

Keep them to at most 1/3 rated V and they should be fine.

NT