[sdiy] Tantalums in general

[Jerry Gray-Eskue]

There are a variety of types, just as there are a variety of electrolytic
caps. There are electrolytic that Should Not be used in power supplies and
others so tough they can do Photo Flash or Welding applications. It all a
matter of matching capacitor specifications such as ESR to the application.
Just think of the variety of voltage ratings, there is as much variation on
other key parameters important for specific requirements. This is true
regardless of the technology used in the construction, Tantalums do have
some Very desirable characteristics in general.

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Sadpaul
Sent: Wednesday, June 10, 2009 7:15 PM
To: Synth DIY
Subject: Re: [sdiy] Tantalums in general


if tantalum is bad for power supplies why are they used in MFOS + -
wall wart power supply?




On Jun 10, 2009, at 6:40 PM, George Hearn wrote:

> Sorry to put a spanner in the works on this thread but I do
> disagree with
> some of what has been said.  Tantalum is a solid electrolyte device
> and
> generally chosen over liquid electrolytes (Aluminium electrolytic
> etc.) when
> reliability and long term stability is paramount.
> 	One good example is PC motherboards, good ones will advertise the
> use of solid capacitors, e.g. tantalum, as aluminium electrolytics
> are prone
> to fail when subjected to the high temperatures often seen in
> modern high
> clock rate systems.  Even if they do not fail their capacitance can
> reduce
> dramatically.
> 	For long time constant circuits I guess tantalum might be quite good
> if you need a large capacitance but in my years I have never had to
> use one
> for this application.  I would be interested to know what their DC
> performance is in terms of change of capacitance with applied DC
> voltage...
> George
>
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of John Henson
> Sent: 11 June 2009 00:12
> To: synth-diy at dropmix.xs4all.nl; Gil W.
> Subject: Re: [sdiy] Tantalums in general
>
> Hi All,
> back in the days tantalum capacitors had (still have} two redeeming
> features...
> Low leakage and very low ESR.
> The former is self explanatory and the latter meant it could
> decouple up to
> fairly high frequencies without a parallel mounted polyester or
> ceramic.
> The end of the tantalum era came when the price of tantalum ore
> skyrocketed
> following political instability in the worlds only source of
> suitable ore
> (Zaire IIRC).
> Tantalum capacitors are even now horrendously expensive compared to
> 'lytics.
> The loss of tantalum meant rapid research into electrolytes giving
> us the
> low ESR 'lytics we enjoy today.
> If you have a synth, module, whatever, with tants decoupling the power
> rails, remove them and replace with low ESR 'lytics. It could save
> a gig one
>
> day.
> Tants as the timing elements in envelope generators or LFO's are
> fine, this
> is the application at which they excel.
> Regards
> John
> ----- Original Message -----
> From: "Gil W." <gil_we at yahoo.com>
> To: "Samppa Tolvanen" <samppa.tolvanen at gmail.com>
> Cc: <synth-diy at dropmix.xs4all.nl>
> Sent: Wednesday, June 10, 2009 9:05 PM
> Subject: Re: [sdiy] Tantalums in Yamaha CS20M/CS40M
>
>
>>
>> What was the reason they used tanatalums at all, back in the days ?
>> The writing on the circuit board, where the tantalum lay, shows the
>> positive mark rather than the negative one as like any other
>> polarized
>> capacitor, meaning they planned dropping tantalums in there at the
>> first
>> place.... Any particular reason ?
>>
>>
>>
>> --- On Wed, 6/10/09, Samppa Tolvanen <samppa.tolvanen at gmail.com>
>> wrote:
>>
>>> From: Samppa Tolvanen <samppa.tolvanen at gmail.com>
>>> Subject: Re: [sdiy] Tantalums in Yamaha CS20M/CS40M
>>> To: "Gil W." <gil_we at yahoo.com>
>>> Cc: "synth-diy at dropmix.xs4all.nl" <synth-diy at dropmix.xs4all.nl>
>>> Date: Wednesday, June 10, 2009, 10:47 PM
>>> On Wed, Jun 10, 2009 at 9:52 PM, Gil
>>> W.<gil_we at yahoo.com>
>>> wrote:
>>>>
>>>> Particularly the power supply... There are four
>>> 1uf/35v tants in there, can I just drop 1uf electrolytes
>>> instead of them ?
>>>>
>>>
>>> I'd say it's more than safe. Electrolytics die, but
>>> Tantalums.are.prone to commit a messy suicide.
>>>
>>> Samppa
>>>
>>
>>
>>
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>>
>
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