Film capacitor as power-supply filter

On 7 Oct 2019 18:05:44 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Phil Allison wrote...

Winfield Hill wrote:

Electrolytic leakage currents must create
small carbon pathways, that's not good.

Leakage current with high voltage electros is normal,
adding " balancing " Rs to a series pair only increase
it by forcing one cap to a higher voltage.

Excuse me! Where do you think those currents through
an insulator are coming from? Any forming processes
aside, high-voltage leakage,** over-voltage, or over
anodization, which we're talking about, involves series
current pathways, carbon formation, corrosion, oxygen
loss, and eventually, failure. The currents increase
exponentially with modest over-voltage.

That is precisely the charm of wet aluminum caps. The series string
optimizes itself for minimum possible leakage current.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Tuesday, 8 October 2019 01:13:35 UTC+1, Phil Allison wrote:

bloggs.fre...@gmail.com wrote:

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


Look at the ripple voltage and verify that your film can take the
ripple current.

** Absurd advice.

Then there is the turn-on time of the circuit. Does this Heath Kit have a lot of tubes in it, or what kind of electronic does it have. The old tube circuit DC supplies would overshoot at turn-on until the tube filaments warmed up and the tubes started conducting, drawing down the rail voltage.

** Funny how rectifier tubes have long warm up times too.

Until then, the applied DC voltage rail would be way high, like 150% nominal.


** Whata pile of fucking crap !!!

Even with silicon diodes in the PSU, the voltage excess is never more than 15% - something electros ARE rated for FFS.


And this could last for tens of seconds.

** No it wouldn't.

The electrolytics are designed to handle this temporary overvoltage, usually spec'd for 30 seconds, the film definitely are not.

** More complete bullshit .

Film caps have plenty of overvoltage capacity, most do not break down until double or triple DC voltage is applied.

Go away you alarmist IDIOT !!!


.... Phil

Secondary power lines in valve gear are often effectively dividers, using a series R to drop a lot of the main PSU voltage. Caps filtering those often see way more V during warm up if the rectifier conducts before the other valves, often more than +50%.


NT

 

On Tuesday, 8 October 2019 02:05:56 UTC+1, Winfield Hill wrote:

Phil Allison wrote...
Winfield Hill wrote:

Electrolytic leakage currents must create
small carbon pathways, that's not good.

Leakage current with high voltage electros is normal,
adding " balancing " Rs to a series pair only increase
it by forcing one cap to a higher voltage.

Excuse me! Where do you think those currents through
an insulator are coming from? Any forming processes
aside, high-voltage leakage,** over-voltage, or over
anodization, which we're talking about, involves series
current pathways, carbon formation, corrosion, oxygen
loss, and eventually, failure. The currents increase
exponentially with modest over-voltage. Proper usage
is spelled out in the Guideline for use of aluminium
electrolytic capacitors, DIN 45811, and elsewhere.

** Low-voltage applications don't use series capacitors.

Leakage is a normal part of electrolytic operation.


NT

 

[Winfield Hill]

tabbypurr@gmail.com wrote...

On 8 October 2019, Winfield Hill wrote:
Phil Allison wrote...
Winfield Hill wrote:

Electrolytic leakage currents must create
small carbon pathways, that's not good.

Leakage current with high voltage electros is normal,
adding " balancing " Rs to a series pair only increase
it by forcing one cap to a higher voltage.

Excuse me! Where do you think those currents through
an insulator are coming from? Any forming processes
aside, high-voltage leakage,** over-voltage, or over
anodization, which we're talking about, involves series
current pathways, carbon formation, corrosion, oxygen
loss, and eventually, failure. The currents increase
exponentially with modest over-voltage. Proper usage
is spelled out in the Guideline for use of aluminium
electrolytic capacitors, DIN 45811, and elsewhere.

** Low-voltage applications don't use series capacitors.

Leakage is a normal part of electrolytic operation.

I understand the normal leakage. But excess leakage one
sees after over anodization, etc., high leakage that only
gets worse with time, that's got to be part of a failure
process. Once the formed oxide layer has been thoroughly
penetrated, new processes can take place ...


--
Thanks,
- Win

 

On Wednesday, 9 October 2019 19:25:08 UTC+1, Winfield Hill wrote:

tabbypurr wrote...
On 8 October 2019, Winfield Hill wrote:
Phil Allison wrote...
Winfield Hill wrote:

Electrolytic leakage currents must create
small carbon pathways, that's not good.

Leakage current with high voltage electros is normal,
adding " balancing " Rs to a series pair only increase
it by forcing one cap to a higher voltage.

Excuse me! Where do you think those currents through
an insulator are coming from? Any forming processes
aside, high-voltage leakage,** over-voltage, or over
anodization, which we're talking about, involves series
current pathways, carbon formation, corrosion, oxygen
loss, and eventually, failure. The currents increase
exponentially with modest over-voltage. Proper usage
is spelled out in the Guideline for use of aluminium
electrolytic capacitors, DIN 45811, and elsewhere.

** Low-voltage applications don't use series capacitors.

Leakage is a normal part of electrolytic operation.

I understand the normal leakage. But excess leakage one
sees after over anodization, etc., high leakage that only
gets worse with time, that's got to be part of a failure
process. Once the formed oxide layer has been thoroughly
penetrated, new processes can take place ...

Leakage current going high & the cap reforming at power-on is not always failure or imminent failure.


NT

 

[Phil Allison]

Winfield Hill the Desperate Bullshitter wrote:

Leakage is a normal part of electrolytic operation.

I understand the normal leakage. But excess leakage one
sees after over anodization, etc.,

** That sudden crashing sound you just heard was Win throwing the context right out the door - so he could bring in a new and improved one.

Gotta admire his blatant subterfuge.



...... Phil

 

On Wednesday, 9 October 2019 21:29:12 UTC+1, Phil Allison wrote:

tabbypurr wrote:
-----------------------


Secondary power lines in valve gear are often effectively dividers, using a series R to drop a lot of the main PSU voltage. Caps filtering those often see way more V during warm up if the rectifier conducts before the other valves, often more than +50%.


** The alarmist, idiot OP posted " way high, like 150% nominal" .

In any case, tube devices must be OK to run with some or all tubes removed.

In 50 years of working on such gear, I have never seen or heard of one that was not.

Eg

Fender instrument amps have all electros after the main PSU filter rated for 500V continuous.


.... Phil

Yes. Your point?

 

[Phil Allison]

tabb...@gmail.com wrote:
-----------------------

Secondary power lines in valve gear are often effectively dividers, using a series R to drop a lot of the main PSU voltage. Caps filtering those often see way more V during warm up if the rectifier conducts before the other valves, often more than +50%.

** The alarmist, idiot OP posted " way high, like 150% nominal" .

In any case, tube devices must be OK to run with some or all tubes removed.

In 50 years of working on such gear, I have never seen or heard of one that was not.

Eg

Fender instrument amps have all electros after the main PSU filter rated for 500V continuous.


..... Phil

 

[Phil Allison]

Some Criminal Nut case called tabb...@gmail.com wrote:
----------------------------------------------------

Yes. Your point?

** Obvious to anyone who is not a trolling mental defective.

FOAD


..... Phil

 

On Wednesday, 9 October 2019 22:46:25 UTC+1, Phil Allison wrote:

Some Criminal Nut case called tabby wrote:
----------------------------------------------------


Yes. Your point?


** Obvious to anyone who is not a trolling mental defective.

FOAD

It's obvious you had nothing to add.

 

On Wednesday, October 9, 2019 at 10:14:57 PM UTC-4, Winfield Hill wrote:

I purchased a really useful instrument, a HANEG** HM2814A,
for electrolytic capacitor leakage tests. The instrument
works to 500V, has multiple test settings, current limits,
meter readouts and diagnostics. My designs use lots of
450V electrolytic capacitors, some in series, and I often
check them on this instrument. I've encountered new-stock
but maybe older* 450V caps, designed for use at 380V, but
with massive excess leakage at only 350 volts. From the
increasing current levels, I'm convinced that these parts
would fail, if forced to operate at their design voltage
(note: 18% safety margin). I didn't test to destruction.

Exactly why I'm fixing up this vintage Heathkit IT-11. It's great for re-forming and for testing leakage. I am going to calibrate the leakage tests so I know how many microamps is the pass/fail threshold for each of the three. And probably change them to whatever I think is useful with modern capacitors.

 

[Winfield Hill]

tabbypurr@gmail.com wrote...

Winfield Hill wrote:
tabbypurr wrote...

Leakage is a normal part of electrolytic operation.

I understand the normal leakage. But excess leakage one
sees after over anodization, etc., high leakage that only
gets worse with time, that's got to be part of a failure
process. Once the formed oxide layer has been thoroughly
penetrated, new processes can take place ...

Leakage current going high & the cap reforming at power-on
is not always failure or imminent failure.

Yes, right.

Classic old-capacitor reforming is done with a forgiving
environment, like a 1k series resistor, etc. What about
an instrument that's powered up after having been off for
a decade or two? What about excessive currents, are they
really only forming currents?

I purchased a really useful instrument, a HANEG** HM2814A,
for electrolytic capacitor leakage tests. The instrument
works to 500V, has multiple test settings, current limits,
meter readouts and diagnostics. My designs use lots of
450V electrolytic capacitors, some in series, and I often
check them on this instrument. I've encountered new-stock
but maybe older* 450V caps, designed for use at 380V, but
with massive excess leakage at only 350 volts. From the
increasing current levels, I'm convinced that these parts
would fail, if forced to operate at their design voltage
(note: 18% safety margin). I didn't test to destruction.

From what I've seen, none of the manufacturer's lengthy
design notes deal with this failure mode. I've had lots
of experience with carbon pathways that behave this way.
The leakage currents continue to increase without limit.

* Lots of my new inventory is 15 to 20 years old, arrgh!

** The name is HANEG, but its HM part number implies HAMEG,
so I placed its info in my HAMEG folder. A made-in-China
thingie, Google doesn't have much info about HM2814A, but
gives a name Jinyitong Electronics. It came with a good
manual, and very useful accessories, but no mention of a
manufacturer's name. But it's a very useful instrument.


--
Thanks,
- Win

 

On Thursday, 10 October 2019 03:14:57 UTC+1, Winfield Hill wrote:

tabbypurr wrote...
Winfield Hill wrote:
tabbypurr wrote...

Leakage is a normal part of electrolytic operation.

I understand the normal leakage. But excess leakage one
sees after over anodization, etc., high leakage that only
gets worse with time, that's got to be part of a failure
process. Once the formed oxide layer has been thoroughly
penetrated, new processes can take place ...

Leakage current going high & the cap reforming at power-on
is not always failure or imminent failure.

Yes, right.

Classic old-capacitor reforming is done with a forgiving
environment, like a 1k series resistor, etc.

Yes, and sometimes the unit itself provides that. And sometimes it doesn't but C survives & reforms.

What about
an instrument that's powered up after having been off for
a decade or two?

'what about' is always a too-vague question

What about excessive currents, are they
really only forming currents?

Excessive currents are by definition excessive, though nothing is said there about the definition that makes it so.
Some caps reform, some don't. A variac or limited current dc psu is useful.
The need for a reform does not always mean a cap is faulty or nearing failure, sometimes it does.


NT

 

[Bill Sloman]

On Thursday, October 10, 2019 at 9:59:16 AM UTC+11, tabb...@gmail.com wrote:

On Wednesday, 9 October 2019 22:46:25 UTC+1, Phil Allison wrote:
Some Criminal Nut case called tabby wrote:
----------------------------------------------------


Yes. Your point?


** Obvious to anyone who is not a trolling mental defective.

FOAD

It's obvious you had nothing to add.

NT never has, and

 

On 9 Oct 2019 19:14:47 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

tabbypurr@gmail.com wrote...
Winfield Hill wrote:
tabbypurr wrote...

Leakage is a normal part of electrolytic operation.

I understand the normal leakage. But excess leakage one
sees after over anodization, etc., high leakage that only
gets worse with time, that's got to be part of a failure
process. Once the formed oxide layer has been thoroughly
penetrated, new processes can take place ...

Leakage current going high & the cap reforming at power-on
is not always failure or imminent failure.

Yes, right.

Classic old-capacitor reforming is done with a forgiving
environment, like a 1k series resistor, etc. What about
an instrument that's powered up after having been off for
a decade or two? What about excessive currents, are they
really only forming currents?

I purchased a really useful instrument, a HANEG** HM2814A,
for electrolytic capacitor leakage tests. The instrument
works to 500V, has multiple test settings, current limits,
meter readouts and diagnostics. My designs use lots of
450V electrolytic capacitors, some in series, and I often
check them on this instrument. I've encountered new-stock
but maybe older* 450V caps, designed for use at 380V, but
with massive excess leakage at only 350 volts. From the
increasing current levels, I'm convinced that these parts
would fail, if forced to operate at their design voltage
(note: 18% safety margin). I didn't test to destruction.

From what I've seen, none of the manufacturer's lengthy
design notes deal with this failure mode. I've had lots
of experience with carbon pathways that behave this way.
The leakage currents continue to increase without limit.

* Lots of my new inventory is 15 to 20 years old, arrgh!

** The name is HANEG, but its HM part number implies HAMEG,
so I placed its info in my HAMEG folder. A made-in-China
thingie, Google doesn't have much info about HM2814A, but
gives a name Jinyitong Electronics. It came with a good
manual, and very useful accessories, but no mention of a
manufacturer's name. But it's a very useful instrument.

I've heard of people using a variac to slowly bring up an old
instrument.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Winfield Hill]

jlarkin@highlandsniptechnology.com wrote...

I've heard of people using a variac to
slowly bring up an old instrument.

I should try that.


--
Thanks,
- Win

 

[whit3rd]

On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, jla...@highlandsniptechnology.com wrote:

I've heard of people using a variac to slowly bring up an old
instrument.

A switchmode regulated supply, though, takes maximum current input
when voltage is low-to-borderline. So that mainly is good for
unregulated power (or power-wasting series or shunt regulated).
It's also questionable if there's a DC fan, or ferroresonant circuit...

 

[John Larkin]

On Thu, 10 Oct 2019 16:36:35 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, jla...@highlandsniptechnology.com wrote:

I've heard of people using a variac to slowly bring up an old
instrument.

A switchmode regulated supply, though, takes maximum current input
when voltage is low-to-borderline. So that mainly is good for
unregulated power (or power-wasting series or shunt regulated).
It's also questionable if there's a DC fan, or ferroresonant circuit...

I meant an OLD instrument.

 

[John Larkin]

On Thu, 10 Oct 2019 17:00:16 -0700 (PDT), Michael Terrell
<terrell.michael.a@gmail.com> wrote:

On Thursday, October 10, 2019 at 7:40:27 PM UTC-4, John Larkin wrote:
On Thu, 10 Oct 2019 16:36:35 -0700 (PDT), whit3rd wrote:

On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, John Larkin wrote:

I've heard of people using a variac to slowly bring up an old
instrument.

A switchmode regulated supply, though, takes maximum current input
when voltage is low-to-borderline. So that mainly is good for
unregulated power (or power-wasting series or shunt regulated).
It's also questionable if there's a DC fan, or ferroresonant circuit...

I meant an OLD instrument.

Back in the '60 and '70s we would apply 12 to 24 volts to old equipment to warm the power transformer to drive out moisture. The tubes were pulled, first and it was left on this setup for 24 hours. It seemed like every old piece of test equipment was store in a dank basement.

I had a Sprague TO6 capacitor analyzer that could reform to 500VDC, and it metered the leakage current. If the oxide layer was bad, you could slowly ramp it up until it had acceptable leakage at the rated voltage. The Military had a set schedule to test and reform NOS electrolytics that were in warehouses. I used to see a lot of surplus caps with a label showing the dates.

Are modern electrolytics any better than the old ones, from the aspect
of un-forming themselves?

Or maybe the old ones are, well, just old.

 

[Michael Terrell]

On Thursday, October 10, 2019 at 7:40:27 PM UTC-4, John Larkin wrote:

On Thu, 10 Oct 2019 16:36:35 -0700 (PDT), whit3rd wrote:

On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, John Larkin wrote:

I've heard of people using a variac to slowly bring up an old
instrument.

A switchmode regulated supply, though, takes maximum current input
when voltage is low-to-borderline. So that mainly is good for
unregulated power (or power-wasting series or shunt regulated).
It's also questionable if there's a DC fan, or ferroresonant circuit...

I meant an OLD instrument.

Back in the '60 and '70s we would apply 12 to 24 volts to old equipment to warm the power transformer to drive out moisture. The tubes were pulled, first and it was left on this setup for 24 hours. It seemed like every old piece of test equipment was store in a dank basement.

I had a Sprague TO6 capacitor analyzer that could reform to 500VDC, and it metered the leakage current. If the oxide layer was bad, you could slowly ramp it up until it had acceptable leakage at the rated voltage. The Military had a set schedule to test and reform NOS electrolytics that were in warehouses. I used to see a lot of surplus caps with a label showing the dates.