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From: miso on 22 Feb 2010 22:56
On Feb 22, 10:40 am, Joerg <inva...(a)invalid.invalid> wrote:
> Ban wrote:
> > Joerg wrote:
> >> Ban wrote:
> >>> Joerg wrote:
> >>>> Fred Abse wrote:
> >>>>> On Sat, 20 Feb 2010 18:08:52 -0800, Joerg wrote:
>
> >>>>>> John Larkin wrote:
> >>>>>>> On Sat, 20 Feb 2010 21:07:48 +0000, Nemo
> >>>>>>> <z...(a)nospam.nospam.nospam.nospam.co.uk> wrote:
>
> >>>>>>>> I am trying to evaluate whether to use tantalum versus OS-CON
> >>>>>>>> aluminium electrolytics as the output decouplers for some linear
> >>>>>>>> postregulators after a (relatively low noise) switcher. This is
> >>>>>>>> for a high gain amplifier that will be operating down to audio
> >>>>>>>> frequencies. I've come across references to aluminium
> >>>>>>>> electrolytics being noisy, but no firm details (kind of odd as
> >>>>>>>> there are lots of details about ceramics' problems under bias,
> >>>>>>>> wet vs dry tantalums etc). There's also some references to "low
> >>>>>>>> noise" aluminium electrolytics for audio work, but I don't know
> >>>>>>>> whether to take them seriously as audiophools believe all kinds
> >>>>>>>> of weird stuff. So, can anyone advise if aluminium electrolytics
> >>>>>>>> - specifically low ESR solid electrolyte types - have some kind
> >>>>>>>> of noise problem? I know tants are NOT microphonic but I've not
> >>>>>>>> come across any info about electrolytics and microphony one way
> >>>>>>>> or another.  Assuming they do not, I favour them over tants
> >>>>>>>> because their ESR
> >>>>>>>> is lower, I get the impression that tants' ESR is poorer at low
> >>>>>>>> frequencies, and I can get electrolytics at higher voltages (I
> >>>>>>>> like to run caps at about double their rated voltage under the
> >>>>>>>> impression this improves their reliability). The load on these
> >>>>>>>> linear regs will be fairly constant, so ripple current will be
> >>>>>>>> low. Thank you,
> >>>>>>> I've never encountered noise from electrolytics. ...
> >>>>>> Oh, I sure did:  pheeeooou ... *BOOM*
> >>>>> I once got the can off one in the crotch, from across the lab.
> >>>>> Makes yer eyes water ;-)
>
> >>>> Ouch, ouch ...
>
> >>>> As a kid I was blissfully unaware of ESR and all those secondary
> >>>> "non-essentials". Fluorescents dimmed ... wait, there's no dimmer on
> >>>> that circuit ... *KABLOUIE* ... phsssooosh ... *POCK* ... phssss
>
> >>>> Followed by some plaster raining down on me and a hissing and
> >>>> smoldering can on the carpet. It had sailed mere inches past my
> >>>> right eye and I sat there all shaking.
>
> >>>> Had to spackle the crater in the ceiling, easy. Also had to get new
> >>>> carpet, from a discount store five miles away, using my bicycle to
> >>>> transport the large and heavy roll. Not so easy.
>
> >>>> This was a serious capacitor, several hundred uF and a few hundred
> >>>> volts, directly fed by a 230V/16A mains line. In a Cockcroft-Walton
> >>>> tripler with numerous other caps feeding a kilowatt-size amplifier.
> >>>> In hindsight it's all pretty amazing that I survived my childhood.
> >>> What a vivid imagination!
>
> > I meant the vivid desciption of your exploding components, you really can
> > differ between a failing MOSFET and passive parts, but nothing seems to beat
> > a tantal.
>
> The biggest tantalums I have ever encountered were the size of a
> thimble. Their (frequent) explosions set off some nice and dazzling
> greenish-orange clouds but the bang was quite modest. This one was a
> serious beker type electrolytic cap, about 8cm long and maybe 4cm
> diameter. Its aluminum tube including innards decided to become a
> spacecraft. Went off like a champagne cork. I could have lost an eye in
> that incident, scary.
>
> > and by imagination was meant to be a special creative talent, unfortunately
> > I worded it ambivalent. ;)
>
> :-)
>
> >> Sorry but your telepathic crystal ball let you down, like before.
>
> >> It happened with a Siemens electrolytic no less. Amplifier with PL509
> >> tubes, tripler from 230VAC to about 900VDC. To be exact, this one,
> >> made by yours truly:
>
> >>http://www.analogconsultants.com/ng/images/PL509amp2.jpg
>
> > I was waiting for the crater in the ceiling tho.
>
> I was too shaken to take a photo back then. Plus after the loud bang my
> dad came running down the stairs, expressed some rather immediate
> ractions of disgust and that it should be fixed, and pronto. Then, he
> saw the smoldering hole in the carpet ...
>
> The only camera I had was a 6cm*6cm children's camera but even B&W film
> was very expensive and I spent all my money on electronics. I wouldn't
> have dared to ask dad for his Agfa 35mm camera at that moment. In
> hindsight I understand his reaction. Back in the 60's it was financially
> hard to build a house when your family had lots of kids and he didn't
> want to see his dream burn down just because I had to have the biggest
> honking amplifier in town.
>
> For US readers: Homes in Germany have concrete ceilings (I wish they
> also did here). There is a roughly 1/2" thick layer of gypsum-based
> plaster applied to that ceiling which is either used as the base to
> apply wallpaper or like in our case it was painted.
>
> --
> Regards, Joerg
>
> http://www.analogconsultants.com/
>
> "gmail" domain blocked because of excessive spam.
> Use another domain or send PM.

Tantalum meltdowns are about the nastiest electronics failure, 2nd
only to lithium ion battery explosions. The deal with tantalum is it
shoots out and then sticks like napalm. If it just went poof and
vaporized, that might be acceptable, but the flying material is
another story.
From: ehsjr on 23 Feb 2010 00:35
miso(a)sushi.com wrote:
> On Feb 22, 10:40 am, Joerg <inva...(a)invalid.invalid> wrote:
>
>>Ban wrote:
>>
>>>Joerg wrote:
>>>
>>>>Ban wrote:
>>>>
>>>>>Joerg wrote:
>>>>>
>>>>>>Fred Abse wrote:
>>>>>>
>>>>>>>On Sat, 20 Feb 2010 18:08:52 -0800, Joerg wrote:
>>
>>>>>>>>John Larkin wrote:
>>>>>>>>
>>>>>>>>>On Sat, 20 Feb 2010 21:07:48 +0000, Nemo
>>>>>>>>><z...(a)nospam.nospam.nospam.nospam.co.uk> wrote:
>>
>>>>>>>>>>I am trying to evaluate whether to use tantalum versus OS-CON
>>>>>>>>>>aluminium electrolytics as the output decouplers for some linear
>>>>>>>>>>postregulators after a (relatively low noise) switcher. This is
>>>>>>>>>>for a high gain amplifier that will be operating down to audio
>>>>>>>>>>frequencies. I've come across references to aluminium
>>>>>>>>>>electrolytics being noisy, but no firm details (kind of odd as
>>>>>>>>>>there are lots of details about ceramics' problems under bias,
>>>>>>>>>>wet vs dry tantalums etc). There's also some references to "low
>>>>>>>>>>noise" aluminium electrolytics for audio work, but I don't know
>>>>>>>>>>whether to take them seriously as audiophools believe all kinds
>>>>>>>>>>of weird stuff. So, can anyone advise if aluminium electrolytics
>>>>>>>>>>- specifically low ESR solid electrolyte types - have some kind
>>>>>>>>>>of noise problem? I know tants are NOT microphonic but I've not
>>>>>>>>>>come across any info about electrolytics and microphony one way
>>>>>>>>>>or another. Assuming they do not, I favour them over tants
>>>>>>>>>>because their ESR
>>>>>>>>>>is lower, I get the impression that tants' ESR is poorer at low
>>>>>>>>>>frequencies, and I can get electrolytics at higher voltages (I
>>>>>>>>>>like to run caps at about double their rated voltage under the
>>>>>>>>>>impression this improves their reliability). The load on these
>>>>>>>>>>linear regs will be fairly constant, so ripple current will be
>>>>>>>>>>low. Thank you,
>>>>>>>>>
>>>>>>>>>I've never encountered noise from electrolytics. ...
>>>>>>>>
>>>>>>>>Oh, I sure did: pheeeooou ... *BOOM*
>>>>>>>
>>>>>>>I once got the can off one in the crotch, from across the lab.
>>>>>>>Makes yer eyes water ;-)
>>
>>>>>>Ouch, ouch ...
>>
>>>>>>As a kid I was blissfully unaware of ESR and all those secondary
>>>>>>"non-essentials". Fluorescents dimmed ... wait, there's no dimmer on
>>>>>>that circuit ... *KABLOUIE* ... phsssooosh ... *POCK* ... phssss
>>
>>>>>>Followed by some plaster raining down on me and a hissing and
>>>>>>smoldering can on the carpet. It had sailed mere inches past my
>>>>>>right eye and I sat there all shaking.
>>
>>>>>>Had to spackle the crater in the ceiling, easy. Also had to get new
>>>>>>carpet, from a discount store five miles away, using my bicycle to
>>>>>>transport the large and heavy roll. Not so easy.
>>
>>>>>>This was a serious capacitor, several hundred uF and a few hundred
>>>>>>volts, directly fed by a 230V/16A mains line. In a Cockcroft-Walton
>>>>>>tripler with numerous other caps feeding a kilowatt-size amplifier.
>>>>>>In hindsight it's all pretty amazing that I survived my childhood.
>>>>>
>>>>>What a vivid imagination!
>>
>>>I meant the vivid desciption of your exploding components, you really can
>>>differ between a failing MOSFET and passive parts, but nothing seems to beat
>>>a tantal.
>>
>>The biggest tantalums I have ever encountered were the size of a
>>thimble. Their (frequent) explosions set off some nice and dazzling
>>greenish-orange clouds but the bang was quite modest. This one was a
>>serious beker type electrolytic cap, about 8cm long and maybe 4cm
>>diameter. Its aluminum tube including innards decided to become a
>>spacecraft. Went off like a champagne cork. I could have lost an eye in
>>that incident, scary.
>>
>>
>>>and by imagination was meant to be a special creative talent, unfortunately
>>>I worded it ambivalent. ;)
>>
>>:-)
>>
>>
>>>>Sorry but your telepathic crystal ball let you down, like before.
>>
>>>>It happened with a Siemens electrolytic no less. Amplifier with PL509
>>>>tubes, tripler from 230VAC to about 900VDC. To be exact, this one,
>>>>made by yours truly:
>>
>>>>http://www.analogconsultants.com/ng/images/PL509amp2.jpg
>>
>>>I was waiting for the crater in the ceiling tho.
>>
>>I was too shaken to take a photo back then. Plus after the loud bang my
>>dad came running down the stairs, expressed some rather immediate
>>ractions of disgust and that it should be fixed, and pronto. Then, he
>>saw the smoldering hole in the carpet ...
>>
>>The only camera I had was a 6cm*6cm children's camera but even B&W film
>>was very expensive and I spent all my money on electronics. I wouldn't
>>have dared to ask dad for his Agfa 35mm camera at that moment. In
>>hindsight I understand his reaction. Back in the 60's it was financially
>>hard to build a house when your family had lots of kids and he didn't
>>want to see his dream burn down just because I had to have the biggest
>>honking amplifier in town.
>>
>>For US readers: Homes in Germany have concrete ceilings (I wish they
>>also did here). There is a roughly 1/2" thick layer of gypsum-based
>>plaster applied to that ceiling which is either used as the base to
>>apply wallpaper or like in our case it was painted.
>>
>>--
>>Regards, Joerg
>>
>>http://www.analogconsultants.com/
>>
>>"gmail" domain blocked because of excessive spam.
>>Use another domain or send PM.
>
>
> Tantalum meltdowns are about the nastiest electronics failure, 2nd
> only to lithium ion battery explosions. The deal with tantalum is it
> shoots out and then sticks like napalm. If it just went poof and
> vaporized, that might be acceptable, but the flying material is
> another story.

And the stinkiest is a selenium rectifier.

Ed
From: Boris Mohar on 24 Feb 2010 07:42
On Sun, 21 Feb 2010 11:41:21 -0800, Fred Abse <excretatauris(a)invalid.invalid>
wrote:


>>
>>
>> Oh, I sure did: pheeeooou ... *BOOM*
>
>I once got the can off one in the crotch, from across the lab. Makes yer
>eyes water ;-)

Many moons ago I was staring at the top of this electrolytic cap that had a
solder safety vent on top. It was bulging and running hot. Suddenly the
vent blew and a volcano of hot electrolyte sprayed directly in my face.
Luckily I was wearing glasses so I escaped wit minor burns but got to keep my
eyesight.

--
Boris
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