Capacitor question ...............

[carlso]

I need to show my ignorance and ask for some guidance.
I have purchased two different caps from Digi-Key and am not sure why nor which ones would be best to use. So would somebody please set me straight.

package #1


package #2


I probably should have ordered 220uf but I didn't. The AVX has 10% on it but the Panasonic does not. Either one of these be OK to use?

Thanks for your help.
Be well,
Carl

[reinhardtjh]

The Panasonic are Poly Tantalum caps which have a somewhat better voltage tolerance.  The rule of thumb for typical tantalum caps is you only want to approach about 50-60% of their rated voltage, in this case 20V which would be 10-12V.  Whereas the Poly Tantalum caps the rule is about 80% which would be around 17-18V.  That's just one of those guidelines.  People exceed them most of the time with no ill effect, but cautious designers/users try to follow them. 

Use the Poly Tantalums first.  Then either get more or decide about taking the risk (of a small explosion/fire in your loco) with the regular ones.

[Steveruger45]

Carl,
I would use the poly tantalums in preference for reasons as mentioned by John’s post.
I have used tantalum caps but have now gotten rid of them.

[carlso]

Thank you John and Steve. Now I remember buying the "poly" caps for the very reason you guys mentioned. Must be my age as I looked at both of these packages and absolutely missed the "poly" tag. Boy it is heck to be "slower". I shall use the poly caps. I have some 220uf 16v that will go out along with the plain tantalums.

Thanks again, great help,
Carl