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Projects => Tech Help - Projects Page => Topic started by: tenwatt on April 01, 2011, 10:52:34 AM

Title: Polarity of Tantalum Caps
Post by: tenwatt on April 01, 2011, 10:52:34 AM
So I have this Tantalum cap that I'm putting on my Egodriver board.  How do I tell which side is positive?  My common sense guess is the right side, in the picture below, because it has the positive sign in the small lettering above that lead.  But that's my uneducated guess.

(http://i980.photobucket.com/albums/ae285/guyskankrye/IMG_3815.jpg)
Title: Re: Polarity of Tantalum Caps
Post by: gtr2 on April 01, 2011, 11:16:10 AM
Usually the positive lead is slightly longer as well, but that doesn't look like the case based on your picture. Unless you already trimmed the leads.

Josh
Title: Re: Polarity of Tantalum Caps
Post by: tenwatt on April 01, 2011, 12:10:48 PM
Quote from: gtr2 on April 01, 2011, 11:16:10 AM
Usually the positive lead is slightly longer as well, but that doesn't look like the case based on your picture. Unless you already trimmed the leads.

Josh
Nope, I didn't trim them yet.  I actually knew that believe it or not. :)

So am I correct in my assumtion of the print on the cap.  It doesn't look like it is really labeling the lead as much as it's just describing the cap.
Title: Re: Polarity of Tantalum Caps
Post by: gtr2 on April 01, 2011, 12:17:45 PM
I'd go for it!

Josh
Title: Re: Polarity of Tantalum Caps
Post by: oldhousescott on April 01, 2011, 01:02:57 PM
The bar or stripe indicates the positive lead on a tantalum cap. Exactly the opposite of an electrolytic.
Title: Re: Polarity of Tantalum Caps
Post by: tenwatt on April 01, 2011, 03:00:02 PM
The third page here gave me my answer.  It's not so clear looking at the cap but the drawing here really helped.

http://www.kemet.com/kemet/web/homepage/kechome.nsf/vapubfiles/F3100_TaDipRad.pdf/$file/F3100_TaDipRad.pdf
Title: Re: Polarity of Tantalum Caps
Post by: bigmufffuzzwizz on April 30, 2011, 04:40:15 PM
Quote from: oldhousescott on April 01, 2011, 01:02:57 PM
The bar or stripe indicates the positive lead on a tantalum cap. Exactly the opposite of an electrolytic.

Took me awhile to spot this the first time. Some of them also have a nice miniature plus sign.