Re: tantalum caps was emc success

Hi,

Yes, you have been lucky. Here's an example of how to change your
luck:)

You have designed a circuit that will run on +12VDC and will have a
voltage regulator to provide said +12VDC. It also has a tantalum cap
across the power rails. In the meantime you want to test the circuit
using your lab power supply, now set to +12VDC and ready to go. You
connect power leads to the supply when BANG! the tantalum cap
disappears in a cloud of smoke. What did you do wrong?

Well, you should have brought the supply up after connecting it to
the circuit, but how many people do that particularly when changes to
the circuit are flying thick and fast?

Was the cap bad? No, but it is fragile compared to other caps. Is it
bad design practice? No, but it is bad testing practice. Will other
tantalums "out there" go bad? Not if they are operating within their
limits.

Mariss

--- In CAD_CAM_EDM_DRO@egroups.com, ballendo@y... wrote:
> Wally K, Jeff, Jon E, Mariss, List,

> I too have used tantalums' where they seemed to make sense. Never
> blown one up. No electrolytics, either. So I gotta ask myself, "Do
I
> feel lucky?... Well, Do I...?
>
> What I want to know is:
> Is this a situation (like selenium rectifiers, and OLD paper/wax
> capacitors) where the value, or other operational characteristics
(of
> the tantalum cap) change, and LEAD to the "flash, Bang, and white
> smoke"?
>
> Or is it like Wally K sez, Bad DESIGN practice???
>
> I'd sure like as definitive answer as possible! (I've got
> tantalums "out there"!)
>
> Ballendo