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Projects => Tech Help - Projects Page => Topic started by: Alrod on July 15, 2012, 04:30:03 PM

Title: Tantalum capacitors
Post by: Alrod on July 15, 2012, 04:30:03 PM
I am getting to build a Grapevine as well as a YellowShark.  I have some Tantalum capacitors that I can use for the builds, but there are no +/- markings on the board.  So here is my (stupid) question, since Tantalum capacitors are polarized, how do i know which way to put them?  Also, I noticed that the Tantalum capacitors that I have don't show any +/- markings.  So my second (stupid) question is, are all Tantalum capacitors polarized?  Thanks.
Title: Re: Tantalum capacitors
Post by: mgwhit on July 15, 2012, 05:39:33 PM
These sound like perfect excuses not to use Tantalum capacitors.

When using polarized caps in builds, I try to put the positive side facing parts of the circuit that carry DC.  Or negative side facing path to ground.  Preferably both.

Tantalum caps are definitely polarized (and prone to catastrophic failure).  If they're not marked, check to see if the leads are different lengths.  Longer lead should be positive.  Good luck.
Title: Re: Tantalum capacitors
Post by: culturejam on July 16, 2012, 12:14:30 AM
Modern tants have a small marking on them to show which is the positive lead, usually.
Title: Re: Tantalum capacitors
Post by: Scruffie on July 16, 2012, 12:18:08 AM
Possibly one longer lead than the other too?
Title: Re: Tantalum capacitors
Post by: midwayfair on July 16, 2012, 01:22:00 AM
I think the OP is saying that the board he's using doesn't have the pads marked + and -. mgwhit's advice is sound, but you should also check the schematic and working out which hole connects to which part.

If you're considering using polarized caps in place of nonpolarized caps for C6 and C11, the negative side faces toward the "out" of the circuit, away from the power source and the input signal. Think about polarized output caps you may have seen in other schematics.