[sdiy] Tantalums in general

[Jerry Gray-Eskue]

There are a number of variations on tantalum caps (wet and dry) now days,
and if you take a 1000uf for example any of the tantalum listed by Mouser
(27,791 to 32,700 Aluminum Electrolytic )are much more expensive than the
Electrolytic. If anyone is curious about them there are plenty of data
sheets available on the website.



-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of George Hearn
Sent: Wednesday, June 10, 2009 6:40 PM
To: synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] Tantalums in general


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
>>
>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>


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