Capacitor polarity -- how to tell with confusing markings?

"larry moe 'n curly"

BTW

All those caps are f****ng antiques.

........ Phil

Point the first: Those look a lot more like tantalum caps than any electrolytic I've ever encountered. Point the second: According to how I learned to count, there are *FIVE* caps in that picture.

Look for the "longer" lead when the dots are confusing. If there isn't one obviously longer, look for the one that's "straightest" coming out of the body of the cap - Notice how on the three right-most ones, the marked lead is significantly more "looped" than the un-marked lead?

Which makes me think that the best first-guess for the second from the left would be the rightmost lead. The leftmost cap I can't really tell - It's cut off too short to try to "read" the leads. However, it *APPEARS* that the leftmost lead is going to be the one that's "supposed to be" marked.

--- Yes, but electrolytics nonetheless.

What 'electrolytic' denotes is that the dielectric is formed by an electrolyte, just as it is in aluminum electrolytics. That's the reason why electrolytics are polar; the electrolyte chemically forms the non-conducting dielectric film on the 'plates' when voltage is applied between them in one direction and removes it when applied in the other direction, shorting out the plates.

-- John Fields Professional Circuit Designer

Good morning, Dr. Howard, Dr. Fine, and Dr. Howard. The other posts have given good advice. However, if all else fails, you can do a leakage test like this: | | .------. | | | | | 1K 2W| 10K | +| .-. ___ | 12V --- | |

Have a Look there:

HTH,

Jorgen

Have a look here:

HTH

Jorgen

what are these called?? Frog caps?

"John Fields" "Phil Allison"

The ones in the pic are "solid tantalum" ( aka "bead tantalum" ) types which have a dry electrolyte ( manganese dioxide) unlike "wet" tantalums or aluminium electrolytic capacitors.

......... Phil