piclist 2007\03\20\062350a >
Thread: Electrolytics and Voltage
face BY : Russell McMahon email (remove spam text)

> My point exactly.  If it were a reliability issue there'd be far
> more in
> the various data sheets about it.

If that were true then all tantalum capacitor data sheets would come
with a large red skull and cross bone sprinted on them and be locked
in hermetically sealed boxes :-).

ie tantalums are superb capacitors, but take them hardly above rated
voltage with a voltage spike of even trivially low energy content, or
connect then reverse polarity and, if there's substantial energy
available in the circuit (as opposed to eg the spike which triggered
the avalanche)  then you'll usually get some or all of shrieking,
smoke (very noxious), flame or explosion and end with a very very very
hard short circuit across the terminals. I've seen a capacitor that
gave ALL these in sequence. Great fun. For good measure in a metal can
tantalum (rare) you may get a hole in the side where you can view the
now solid bead of tantalum rolling to and fro.

ie data sheets may be somewhat mealy mouthed about the extent of
hazards which exist outside the specified operating range. Stay in
spec and all is well. Exceed spec and, oh dear. This applies in more
than just EE - eg try and find solid official comment  in MSDSs or
elsewhere on the toxic or lethal dosage of acetaminophen/panadol. It
can be as little as < twice the daily max recommended dose but try and
find that written down somewhere.

ie the job of the spec sheet is to tell you about in spec operation.
Not, alas, how far you can go outside spec. Sometimes its grey. What?
You ran our 100 volt caps at 5 volts? Why would you do that ?



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Subject (change) Electrolytics and Voltage

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