> I've seen resistors smoke and explode a lot
> too, maybe we should all stop using resistors. ;o)

Late breaking thought :-) -

Resistors require substantial external energy to destroy them and if run
inside rated specs requires substantial energy either as a very large
shortish spike or a sustained moderate overvoltage to die (provided voltage
ratings are not grossly exceeded). Failure mode is most often open circuit.

Whereas a Tantalum capacitor stores substantial energy within itself and
when subject to a low energy transient that causes it to break down, uses
its own stored energy to destroy itself. The transient can be VERY brief.
Once the oxide layer is gone the cap is too. They usually produce a superb
hard metallic short which makes for excellent crowbar protection. Few power
supplies have enough energy to break the short of a short-circuit Tantalum.
I have seen a 5v  several hundred amp supply manage to do so (DEC PDP11
computer) - there was a nice Tantalum metal bead rattling around inside the
case :-).

Al wet electrolytics when subject to substantial overvoltage (or reverse
voltage) will after a while blow out their end, eject a wad of innards and
spray caustic electrolyte everywhere. But they lack the satisfying true
explosion of a Tantalum and I have never seen an Al cap emit a jet of flame
as Tantalums sometimes do. .



            Russell McMahon

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