Al electro's vs polymer?

[George Herold]

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

 

[George Herold]

On Tuesday, August 27, 2019 at 1:32:29 PM UTC-4, George Herold wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Oh, 15V supply
GH

 

[John Larkin]

On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.

Polymers have very low ESR. That may or may not matter in your filter.
Wet aluminums can be had with bigger capacitance values.

You could get voltage overshoot from the LC combination, so make sure
the polymer caps are rated for at at least 2x the supply voltage. I've
tested some that die hard at 1.5x rated voltage. Panasonic?

The United Chem-Com parts are great. At way over rated voltage, and a
bunch of reverse voltage too.

 

[Phil Hobbs]

On 8/27/19 1:39 PM, George Herold wrote:

On Tuesday, August 27, 2019 at 1:32:29 PM UTC-4, George Herold wrote:
Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Oh, 15V supply
GH

Al poly has way lower ESR for the same capacitance, and ought to last
longer at highish temperature because there's nothing to dry out.

Usefully, Alpos come in all sorts of grades of ESR, so you can find one
that will work with your regulator. They do cost more for a given value
and voltage, but the ESR improvement may let you use a smaller one.

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

 

[George Herold]

On Tuesday, August 27, 2019 at 1:54:56 PM UTC-4, Phil Hobbs wrote:

On 8/27/19 1:39 PM, George Herold wrote:
On Tuesday, August 27, 2019 at 1:32:29 PM UTC-4, George Herold wrote:
Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Oh, 15V supply
GH


Al poly has way lower ESR for the same capacitance, and ought to last
longer at highish temperature because there's nothing to dry out.

Usefully, Alpos come in all sorts of grades of ESR, so you can find one
that will work with your regulator. They do cost more for a given value
and voltage, but the ESR improvement may let you use a smaller one.

Cheers

Phil Hobbs

Thanks Phil, I guess I'll have to order some of both. I might need a bit of ESR.
The filter looks to have a Q of about 3... so ~ 1 ohm of resistance... I think
shared between L and C. A lower Q would be nice. (maybe a bigger C.)

George H.

--
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

 

[George Herold]

On Tuesday, August 27, 2019 at 2:05:54 PM UTC-4, John Larkin wrote:

On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.

They seem to be getting worse with time. I was looking at a
circuit we made ~20+ years ago and there are 16V tant's on all the
+/-15V rails... Now I've changed to all 50V tants on 15V rails.

George H.

Polymers have very low ESR. That may or may not matter in your filter.
Wet aluminums can be had with bigger capacitance values.

You could get voltage overshoot from the LC combination, so make sure
the polymer caps are rated for at at least 2x the supply voltage. I've
tested some that die hard at 1.5x rated voltage. Panasonic?

The United Chem-Com parts are great. At way over rated voltage, and a
bunch of reverse voltage too.

 

[John Larkin]

On Tue, 27 Aug 2019 11:24:27 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

On Tuesday, August 27, 2019 at 2:05:54 PM UTC-4, John Larkin wrote:
On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.
They seem to be getting worse with time. I was looking at a
circuit we made ~20+ years ago and there are 16V tant's on all the
+/-15V rails... Now I've changed to all 50V tants on 15V rails.

Tantalums are just erratic. Some batches are bulletproof, some
explode, with no apparent pattern.

3x voltage derating seems safe for tants. I like them on the outputs
of LM317 and LM1117 regulators, which don't like all-ceramic loads.

(Unless you do my trick.)

 

[Tim Williams]

Both are available in a wide range of ESR. The range for AlPo is generally
lower, but there is plenty of overlap. Just shop for the appropriate part.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

"George Herold" <gherold@teachspin.com> wrote in message
news:21846874-a45b-407d-8d00-f7e7599524e0@googlegroups.com...

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with
something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

 

[George Herold]

On Tuesday, August 27, 2019 at 7:02:56 PM UTC-4, Tim Williams wrote:

Both are available in a wide range of ESR. The range for AlPo is generally
lower, but there is plenty of overlap. Just shop for the appropriate part.

Thanks Tim, I ended up just searching for all the Al electro's we have
in stock. A bigger 100uF 50V gave a nice 'output'*, and fit!
ESR was less than the tant, but still less ringing at the lower
freq. Better and better, no one but me will really care :^)

George H.

*I'm filtering this commercial SMPS +/-15V at ~1A.. though I don't need
all that current. The positive supply is worse than the negative,
in that it has a ~60Hz ripple and (I assume) the negative supply is
derived from the positive and clean there.

Oh, so here's a thing. Does anyone else look at the spectrum of
some signal by triggering their DSO (normal trig.) up near the
maximum voltage of the signal, and averaging?**
This gives outputs that are 'almost' the auto-correlation function.
And if you press your DSO FFT button, you get displays that are 'almost'
the FFT... (the 'almost' is the FFT falls off faster at high freq.
so the 3db point moves to 6db... that's for a low pass.)

GH
**(if you trigger in the middle of the signal, and average,
you get a much smaller thing, where V(t=0) = 0)

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

"George Herold" <gherold@teachspin.com> wrote in message
news:21846874-a45b-407d-8d00-f7e7599524e0@googlegroups.com...
Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with
something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

 

[George Herold]

On Tuesday, August 27, 2019 at 8:00:00 PM UTC-4, George Herold wrote:

On Tuesday, August 27, 2019 at 7:02:56 PM UTC-4, Tim Williams wrote:
Both are available in a wide range of ESR. The range for AlPo is generally
lower, but there is plenty of overlap. Just shop for the appropriate part.

Thanks Tim, I ended up just searching for all the Al electro's we have
in stock. A bigger 100uF 50V gave a nice 'output'*, and fit!
ESR was less than the tant, but still less ringing at the lower
freq. Better and better, no one but me will really care :^)

George H.

*I'm filtering this commercial SMPS +/-15V at ~1A.. though I don't need
all that current. The positive supply is worse than the negative,
in that it has a ~60Hz ripple and (I assume) the negative supply is
derived from the positive and clean there.

Oh, so here's a thing. Does anyone else look at the spectrum of
some signal by triggering their DSO (normal trig.) up near the
maximum voltage of the signal, and averaging?**
This gives outputs that are 'almost' the auto-correlation function.
And if you press your DSO FFT button, you get displays that are 'almost'
the FFT... (the 'almost' is the FFT falls off faster at high freq.
so the 3db point moves to 6db... that's for a low pass.)

For a Band Pass, higher Q filter it means the ringing happens 'sooner'
in the time domain and I don't know what the scale factor
is for the slopes, (probably sqrt(2) in power. 2dB?)

GH
**(if you trigger in the middle of the signal, and average,
you get a much smaller thing, where V(t=0) = 0)

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

"George Herold" <gherold@teachspin.com> wrote in message
news:21846874-a45b-407d-8d00-f7e7599524e0@googlegroups.com...
Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with
something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

 

[whit3rd]

On Tuesday, August 27, 2019 at 10:32:29 AM UTC-7, George Herold wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)

Why not just stick with aluminum electrolytic? The regular old not-so-low-ESR
caps are fine for lots of purposes, and if you don't like 'em failing with
age, just use two or three. A filter inductor seems to indicate you
don't want to support high surges of current anyhow, so adding a current limiter
(even if it's a fuse) seems more productive than looking for exotic components.

 

[Sjouke Burry]

On 28.08.19 4:53, Phil Allison wrote:

whitless the 3rd wrote:

------------------------


Why not just stick with aluminum electrolytic?
The regular old not-so-low-ESR
caps are fine for lots of purposes, and if you don't like 'em failing with
age, just use two or three.


** Huh ?

Doing that makes them last longer ??

On which planet?

On this one. Ripple current is spread across the 3 caps,
resulting in lower temperature and longer life.

 

On Tue, 27 Aug 2019 11:05:45 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.

Polymers have very low ESR. That may or may not matter in your filter.
Wet aluminums can be had with bigger capacitance values.

You could get voltage overshoot from the LC combination, so make sure
the polymer caps are rated for at at least 2x the supply voltage. I've
tested some that die hard at 1.5x rated voltage. Panasonic?

The United Chem-Com parts are great. At way over rated voltage, and a
bunch of reverse voltage too.

I checked a Panasonic 56u 25V polymer. It's fine at +40 and -10 volts.

 

[Phil Allison]

whitless the 3rd wrote:

------------------------

Why not just stick with aluminum electrolytic?
The regular old not-so-low-ESR
caps are fine for lots of purposes, and if you don't like 'em failing with
age, just use two or three.

** Huh ?

Doing that makes them last longer ??

On which planet?


..... Phil

 

[Phil Allison]

Sjouke Burry wrote:

Phil Allison wrote:

whitless the 3rd wrote:

------------------------


Why not just stick with aluminum electrolytic?
The regular old not-so-low-ESR
caps are fine for lots of purposes, and if you don't like 'em failing with
age, just use two or three.


** Huh ?

Doing that makes them last longer ??

On which planet?


On this one.

** Well, that begs the question ....


> Ripple current is spread across the 3 caps,

** It's too small to matter.

resulting in lower temperature and longer life.

** Nope.

FYI: EVERY case of early electro failure I have seen, the cause was high ambient temp, not ripple current.

Dopey PCB designers placing them too close to hot power semis and resistors.



..... Phil

 

[whit3rd]

On Tuesday, August 27, 2019 at 7:53:55 PM UTC-7, Phil Allison wrote:

whitless the 3rd wrote:

The regular old not-so-low-ESR
caps are fine for lots of purposes, and if you don't like 'em failing with
age, just use two or three.


** Huh ?

Doing that makes them last longer ??

On which planet?

If you need 500 uF, just use three 330 uF units. The usual failure mode
being electrolyte loss/drying out, would leave the failed unit an open circuit,
so the others cover for it.

I've done some troubleshooting on old machines (Mac IIci, if anyone recalls those)
where seal failure could take out about a third of the distributed filter caps
without anyone noticing (unless the electrolyte goo ate through a trace).

 

[Michael Kellett]

On 28/08/2019 04:12, jlarkin@highlandsniptechnology.com wrote:

On Tue, 27 Aug 2019 11:05:45 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.

Polymers have very low ESR. That may or may not matter in your filter.
Wet aluminums can be had with bigger capacitance values.

You could get voltage overshoot from the LC combination, so make sure
the polymer caps are rated for at at least 2x the supply voltage. I've
tested some that die hard at 1.5x rated voltage. Panasonic?

The United Chem-Com parts are great. At way over rated voltage, and a
bunch of reverse voltage too.

I checked a Panasonic 56u 25V polymer. It's fine at +40 and -10 volts.

Interesting,

I had a circuit with a link to enable a -ve 5V supply, due to an
oversight it got pulled up to +2.5V when the link was missing.

The Kemet 100uF 10V caps on the -ve supply (taht had seen the reverse
voltage) all failed between a few minutes and a few hours after the
application of the correct polarity supply.
The really worrying thing is that some of them looked OK for an hour or two.

MK


---
This email has been checked for viruses by AVG.
https://www.avg.com

 

On Wednesday, 28 August 2019 15:15:43 UTC+1, jrwal...@gmail.com wrote:

On Wednesday, 28 August 2019 15:02:21 UTC+1, jla...@highlandsniptechnology.com wrote:
On Wed, 28 Aug 2019 10:42:37 +0100, Michael Kellett <mk@mkesc.co.uk
wrote:

On 28/08/2019 04:12, jlarkin@highlandsniptechnology.com wrote:
On Tue, 27 Aug 2019 11:05:45 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.

Polymers have very low ESR. That may or may not matter in your filter.
Wet aluminums can be had with bigger capacitance values.

You could get voltage overshoot from the LC combination, so make sure
the polymer caps are rated for at at least 2x the supply voltage. I've
tested some that die hard at 1.5x rated voltage. Panasonic?

The United Chem-Com parts are great. At way over rated voltage, and a
bunch of reverse voltage too.

I checked a Panasonic 56u 25V polymer. It's fine at +40 and -10 volts.

Interesting,

I had a circuit with a link to enable a -ve 5V supply, due to an
oversight it got pulled up to +2.5V when the link was missing.

The Kemet 100uF 10V caps on the -ve supply (taht had seen the reverse
voltage) all failed between a few minutes and a few hours after the
application of the correct polarity supply.
The really worrying thing is that some of them looked OK for an hour or two.

MK


Here are some 25V Panasonics run at -10 volts for a month or so. Total
leakage was 46 uA after things settled down (DVM shows drop across a
1K resistor.) There is a bit of "forming", or maybe massive DA, like a
regular lytic, so initial leakage was higher.

Declining leakage is a good sign!

I once had a 16V tantalum bead reverse connected to a 15V power supply.
It lasted a few weeks before it shorted the power supply (capable of a
few hundred mA maximum. There were no pyrotechnics fortunately.

John

 

On Wednesday, 28 August 2019 15:02:21 UTC+1, jla...@highlandsniptechnology.com wrote:

On Wed, 28 Aug 2019 10:42:37 +0100, Michael Kellett <mk@mkesc.co.uk
wrote:

On 28/08/2019 04:12, jlarkin@highlandsniptechnology.com wrote:
On Tue, 27 Aug 2019 11:05:45 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.

Polymers have very low ESR. That may or may not matter in your filter.
Wet aluminums can be had with bigger capacitance values.

You could get voltage overshoot from the LC combination, so make sure
the polymer caps are rated for at at least 2x the supply voltage. I've
tested some that die hard at 1.5x rated voltage. Panasonic?

The United Chem-Com parts are great. At way over rated voltage, and a
bunch of reverse voltage too.

I checked a Panasonic 56u 25V polymer. It's fine at +40 and -10 volts.

Interesting,

I had a circuit with a link to enable a -ve 5V supply, due to an
oversight it got pulled up to +2.5V when the link was missing.

The Kemet 100uF 10V caps on the -ve supply (taht had seen the reverse
voltage) all failed between a few minutes and a few hours after the
application of the correct polarity supply.
The really worrying thing is that some of them looked OK for an hour or two.

MK


Here are some 25V Panasonics run at -10 volts for a month or so. Total
leakage was 46 uA after things settled down (DVM shows drop across a
1K resistor.) There is a bit of "forming", or maybe massive DA, like a
regular lytic, so initial leakage was higher.

Declining leakage is a good sign!

I once had a 16V tantalum bead reverse connected to a 15V power supply. It lasted a few weeks before it shorted the power supply (capable of a few hundred mA maximum. There were no pyrotechnics fortunately.

John

 

On Wed, 28 Aug 2019 10:42:37 +0100, Michael Kellett <mk@mkesc.co.uk>
wrote:

On 28/08/2019 04:12, jlarkin@highlandsniptechnology.com wrote:
On Tue, 27 Aug 2019 11:05:45 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Tue, 27 Aug 2019 10:32:24 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

Enough with these tantalum caps. I've got a 10 uF 35V cap as part of a
power supply filter (w/ 100 uH inductor). I want to replace it with something
else. (I somehow blew this.. by shorting the output?)
What's the difference between Al electro's and the Aluminum-polymer?
And which do I want? The instrument spends all it's time indoors, no wild
temperature changes. These are through hole.

George H.

Tantalums are dangerous across power supply rails.

Polymers have very low ESR. That may or may not matter in your filter.
Wet aluminums can be had with bigger capacitance values.

You could get voltage overshoot from the LC combination, so make sure
the polymer caps are rated for at at least 2x the supply voltage. I've
tested some that die hard at 1.5x rated voltage. Panasonic?

The United Chem-Com parts are great. At way over rated voltage, and a
bunch of reverse voltage too.

I checked a Panasonic 56u 25V polymer. It's fine at +40 and -10 volts.

Interesting,

I had a circuit with a link to enable a -ve 5V supply, due to an
oversight it got pulled up to +2.5V when the link was missing.

The Kemet 100uF 10V caps on the -ve supply (taht had seen the reverse
voltage) all failed between a few minutes and a few hours after the
application of the correct polarity supply.
The really worrying thing is that some of them looked OK for an hour or two.

MK

Here are some 25V Panasonics run at -10 volts for a month or so. Total
leakage was 46 uA after things settled down (DVM shows drop across a
1K resistor.) There is a bit of "forming", or maybe massive DA, like a
regular lytic, so initial leakage was higher.

Declining leakage is a good sign!