tantalum caps

[Saint Louis Toneworks]

reading they can replace electrolytes as long as polarized in place? couldnt get a 10u to work for a 10 u f electrolyte

[armdnrdy]

Are you sure you had the cap oriented correctly?

Electrolytic caps are marked on the negative side, Tantalums are marked on the positive.

[R.G.]

Tantalum caps *are* electrolytic - just using tantalum film electrodes instead of aluminum.

Armdnrdy is correct with the first question - did you have it oriented correctly?

Tantalum is used instead of aluminum for these caps because tantalum oxide films has a higher dielectric coefficient, which makes for higher capacitance per unit volume, and not used for all electrolytic caps because (1) tantalum is more expensive than aluminum and (2) tantalum has some more energetic and entertaining failure modes if you use them incorrectly. Higher performance, more expensive and trickier to deal with.

[Saint Louis Toneworks]

thanks guys i cant read mine, the writing non existent magnified, so i thought longer leg was +

[amptramp]

Tantalum is better in timing circuits because the tantalum pentoxide dielectric tends to be pinhole-free and therefore these caps have low leakage.  If you use them for power supply bypasses, local defects can turn the pentoxide into conductive tantalum dioxide and the heat from this reaction causes more of the dielectric to turn to the dioxide, causing a quick firestorm in the capacitor.  If you have resistance in series with the capacitor, it tends to prevent this effect and timing circuits usually do this.  With series resistance, they make excellent bypass capacitors with high-frequency characteristics similar to ceramic, extending into RF frequencies, something aluminum electrolytics cannot do.

[anotherjim]

Positive lead should be longer -  but if your caps have been un-soldered from a pcb, they will have lost that feature.
Some have a bulge and "knee" on the positive side.

[Saint Louis Toneworks]

they wont work for me ..the circuit fails with a tant 10uf and works perfectly with 10uf electro

[armdnrdy]

they wont work for me ..the circuit fails with a tant 10uf and works perfectly with 10uf electro

Have you tried more than one tant cap? or the one in which the polarity isn't marked?

You may have damaged the one by connecting it in reverse.

See "polarity":
http://www.capacitorguide.com/tantalum-capacitor/

Also...what circuit are you working on? Post a schematic and include the cap number you are having issues with.

[R.G.]

Also see my comments on ronniedee's post, where both ANR and I were working simultaneously too.   

[Saint Louis Toneworks]

yes, I test every single piece on the testor I got from ebay, similar to a peak atlas,  and it reads the same way as the electro - went through a pack of ten testing them  , I even soldered one in to test it as well and got nothing , soon as I p[opped it back out and put in the other cap she fired right back up . i want to use them because they are so small size wise

[armdnrdy]

 Post a schematic and include the cap number you are having issues with.

[Saint Louis Toneworks]

im just rolling with the electro caps - i found a 50 lot of panasonics for 5 dollars on ebay today

I can put some heat shrink on the legs and bend them over

[PRR]

Tants were hot-stuff in the 1970s. They can be better in some ways than Aluminum electrolytic, but designers were throwing them in "everywhere", even when not appropriate. I just read a 1970s construction article advising Tants "for low leakage" in a place where leakage was un-critical, where any healthy Aluminum would have been fine.

1980s some of these Tants blew-up. Aluminum may spew paper-shred, but a Tant power-filter that fails leaves burn-marks on the board.

Also 1980s, Aluminum electrolytics got a LOT better, less leakage in smaller size, and the advantages of Tants became very slim if any.

> a 50 lot ....for 5 dollars on ebay

My advice is DON'T low-ball electrolytic caps. They are some of the most troublesome parts in electronics. Also they cost more than many other parts. This leads to sloppy production, re-sale of factory rejects, and outright fraud (re-branding). Life is too precious to waste tracing and replacing faulty caps.

[Saint Louis Toneworks]

seems like a to good of a deal i know . then again I have sold stuff for close to nothing many times myself - hope they are workable ones lol

I check ebay daily for stuff just like this under new listing because usually cheap deals goes right away

[newperson]

Are you saying you are buying 50 10uF Aluminum Electrolytic caps?  You can get 100 new units for $4.30 from Mouser.  50v 10UF.

http://www.mouser.com/ProductDetail/Panasonic/ECA-1HM100/?qs=sGAEpiMZZMvwFf0viD3Y3Z9Y0KMAiJs%2f0rIfCeMzGho%3d

You can get (100) 100v for $5.30 if you sticking to the Panasonic brand.

[R.G.]

I check ebay daily for stuff just like this under new listing because usually cheap deals goes right away

ebay is many things - including a dumping ground for substandard or counterfeit electronic parts. It's OK to play there if you're capable and willing to cope with the situation if the goods turn out to be junk.