Capacitors!?

[SmurfJ]

Alright, in the perfboard layout i have, there is an "electrolyte" (electrolytic capacitor) on th eboard. a 1uF.  I have at hand a 1uF tantalum capacitor...  Well, the electrolytic is noted on the board positive negative. the tantalum doesnt have a positive and negative. can i still use it? is there somethign special about tantalum??

[Exactopposite]

it's common for electrolytic caps to have polarity (tho there are non polarized elcetrolytics). in general other caps do not have polarity.  i don't know of any reason why you shouldn't be able to use the tantalum of the same value in it's place.

[SmurfJ]

is there a point to the polarity. my other post has the perfboard layout...

[12milluz]

Well having a cap with polarity doesn't affect the circuit, but it would not work if the polarity is reversed. Using that capacitor in place should work fine, as long as the value is the same.

[bean]

Most of the tants I've ever used have a side that is smooth and one side that has a little bump. Usually the bump is the positive side of the cap. Tantalums can be pretty sensitive to polarities and you run the risk of destroying it if you orient it incorrectly.

As far as there being something special, that's really a matter of opinion. A lot of people like them for decoupling. Some don't like them because they can have a higher failure rate than standard electrolytics.

[Sock Puppet]

What???

I was unaware that they made non polarized tantalum but apparently they are two wired back to back and sealed in the same case. 

I have these that came in a huge box of stuff from ebay, I thought they were tantalum but when I had a closer look I dismissed the idea and just thought something new and got on with sorting.

Now I think they're tantalums again.

S.

Well there was going to be a picture but photobucket has a problem.  Maybe later if I remember, I get tired of jumping through hoops just to post something simple.

[Sock Puppet]

http://www.little-black-box.co.uk/index.php?act=viewProd&productId=21

[Sock Puppet]

Oops.

The URL copy ain't working properly, ignore the above - can't find an edit:

http://i273.photobucket.com/albums/jj219/designacryl/cap.jpg

S.

[PerroGrande]

Tantalum capacitors typically have polarity, just like electrolytic capacitors.  Connecting them in the correct manner is important.

On tantalums, the bar indicates the POSITIVE side of the cap.  In your picture, the bar looks a bit like the number "7" and is on the right hand side of the picture.

The trick of connecting two polarized capacitors back-to-back (but with opposite polarities) *will* result in a non-polarized cap.