Three legged tantalum caps?

[soggybag]

I bought some stuff from B.G. Micro. They have some rpetty good deals. I ordered some 22uf tantalum caps, turns out they have three legs? what do you do with these? what's that third leg for? I have never seen this before.

[R.G.]

Tantalum caps explode or flame when put in reversed in some conditions. Manufacturers demanded tantalum caps that could not be put in backwards.

Yes, the (-) pin is in the middle. Both outside pins are (+).

[ryanscissorhands]

I was thinking that the tants were juet a little excited

[zachary vex]

fascinating.

[barret77]

my old gibson amp has them, at first I thought it was a @!#%$ gigantic transistor, but checking the schematics I confirmed they were capacitors

[ESPguitar]

my old gibson amp has them, at first I thought it was a @!#%$ gigantic transistor, but checking the schematics I confirmed they were capacitors

[soggybag]

Thanks, that makes it easy to ufigure out which is the negative lead. The markings too small to read on these.

[KORGULL]

I just got some of the 10uF tantalum caps with three legs from B.G. Micro,  their catalog states that the middle leg is positive and the outside legs are negative. The cap itself has no polarity marks and all leads are the same length.  :? ...I guess I'll go with what the catalog says until one explodes - is there a way to test these with a meter? I got the same (correct) reading either way I hooked up the probes when I checked these caps using my meter's capacitance setting.

[soggybag]

Hmm this may take a closer look. I wonder if there is a way test them? Where did you see the specs on the BG Micro site? I did not see that?

[Paul Perry (Frostwave)]

Here's how I would try to test them for polarity:
put a 10K or so resistor in series with a 9v battery & then connect across the cap and see which way has the lowest voltage across the resistor.
(what this does, is get an indication of the leakage, which would be higher when reversed). Try a higher voltage if the9V doesn't work.

Guess why you shouldn't just put a current meter in series? :!:  :shock:  :x  :oops:  :wink: (in that order)

Oh yes, face & eye protection when you are 'experimenting' with tants!

[KORGULL]

soggybag wrote:

Where did you see the specs on the BG Micro site? I did not see that?

It was in the print catalog, here's the whole quote:
BG Micro:

Sprague Tantalum PC lead cap. This cap is idiot proof in that it has 3 legs.
.1" spacing with the center lead +.
10uF/16V.

Paul Perry
(Frostwave) wrote:

Here's how I would try to test them for polarity:
put a 10K or so resistor in series with a 9v battery & then connect across the cap and see which way has the lowest voltage across the resistor.
(what this does, is get an indication of the leakage, which would be higher when reversed). Try a higher voltage if the9V doesn't work.

Sounds like a good plan