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Thread: Chucking a tantalum?

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    Chucking a tantalum?

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    So I'm cleaning up an old live desk to see if I can use it for anything.

    I've noticed quite a few 10uf tantalum caps inside... and the desk is at least 20 years old, if not 30. I'm going to swap out all the electrolytics as first priority. I also want to ditch all the tantalums due to their age (I understand they "die" like electrolytics after a while...?).

    Assuming I can fit them sizewise, can just I replace the tantalums with new low leak electrolytics? Seems to me it should be a straight swap (observing polarity obviously)? This is only for the polarized ones, btw. Everything else is films already (with ceramic decouplers on some op amps I think).

    Just thought I'd ask as I don't want to order a lot of them if I'm mistaken.

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    Quote Originally Posted by slowmotion View Post
    I've noticed quite a few 10uf tantalum caps inside... and the desk is at least 20 years old, if not 30. I'm going to swap out all the electrolytics as first priority. I also want to ditch all the tantalums due to their age (I understand they "die" like electrolytics after a while...?).
    I get the impression they last a lot longer than electrolytic caps, though I suppose if they are old enough, it still might not be a bad idea.


    Quote Originally Posted by slowmotion View Post
    Assuming I can fit them sizewise, can just I replace the tantalums with new low leak electrolytics? Seems to me it should be a straight swap (observing polarity obviously)? This is only for the polarized ones, btw. Everything else is films already (with ceramic decouplers on some op amps I think).
    Sure. Assuming you're dealing only with applications where polarized caps are acceptable, electrolytic caps should be fine as alternatives to tantalum. If they're in the audio path (it sounds like they probably aren't), you might also consider film caps if you have room for them. There's nothing wrong with using a non-polarized cap where a polarized cap is specified. The reverse, however, is generally a bad idea.
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    Quote Originally Posted by dgatwood View Post
    There's nothing wrong with using a non-polarized cap where a polarized cap is specified.
    as long as the voltage rating takes into account the offset voltage plus the signal level....

    iirc... tantalums can drift in value over time but usually that associated with higher voltages... ymmv..
    37.8% of all statistics are made up on the spot...

    hey give a guy some room... people are trying to evolve here... for crying out loud...

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    Quote Originally Posted by dementedchord View Post
    as long as the voltage rating takes into account the offset voltage plus the signal level....
    You need to do that with a polarized cap, too, unless I'm missing something.
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    Tantalum caps also Fail Catistrophicly when even slighly reverse biased and Can also Short when they Fail which can take out other components...Never liked them as they sound brittle in audio applications....

    War is just a word used to hide the nakedness of their killing ......

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    Quote Originally Posted by dgatwood View Post
    You need to do that with a polarized cap, too, unless I'm missing something.

    yeah kinda looks like another brain fart but i remember trying it once on a piece in the shop and couldnt figure out why it failed... the boss just chuckled and said to double the voltage rateing... wish i could remember what exactly was the deal...
    37.8% of all statistics are made up on the spot...

    hey give a guy some room... people are trying to evolve here... for crying out loud...

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    Quote Originally Posted by Minion View Post
    Tantalum caps also Fail Catistrophicly when even slighly reverse biased and Can also Short when they Fail which can take out other components...Never liked them as they sound brittle in audio applications....


    how do you reverse bias a bipolar cap??
    37.8% of all statistics are made up on the spot...

    hey give a guy some room... people are trying to evolve here... for crying out loud...

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    Bipolar Tantilum...Never ever heard of one or seen one....
    War is just a word used to hide the nakedness of their killing ......

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    Quote Originally Posted by Minion View Post
    Bipolar Tantilum...Never ever heard of one or seen one....
    you had me worried for a second... all i have ever used were bipolar i thought... iirc they were used in the oscillators/generators of some old church organs... but then i checked wiki...


    "Tantalum capacitors are a form of electrolytic capacitor. However, some forms of them are non-polar, containing two capacitors connected in series (negative to negative). "

    somehow i never equated them with electrolytics at all... well there's my fact for the day...
    37.8% of all statistics are made up on the spot...

    hey give a guy some room... people are trying to evolve here... for crying out loud...

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    Yes, generally Tantilum caps are Polarized but like Electrolytics that can be connected end to end to make a Non-polar capacitor.....

    Here is a exerpt from Wikipedia:

    Tantalum: compact, low-voltage devices up to several hundred F, these have a lower energy density and are more accurate than aluminum electrolytics. Tantalum capacitors are also polarized because of their dissimilar electrodes. The cathode electrode is formed of sintered tantalum grains, with the dielectric electrochemically formed as a thin layer of oxide. The thin layer of oxide and high surface area of the porous sintered material gives this type a very high capacitance per unit volume. The cathode electrode is formed either of a liquid electrolyte connecting the outer can or of a chemically deposited semi-conductive layer of manganese dioxide, which is then connected to an external wire lead. A development of this type replaces the manganese dioxide with a conductive plastic polymer (polypyrrole) that reduces internal resistance and eliminates a self-ignition failure.[5]
    Compared to aluminum electrolytics, tantalum capacitors have very stable capacitance, little DC leakage, and very low impedance at high frequencies. However, unlike aluminum electrolytics, they are intolerant of voltage spikes and are destroyed (often exploding violently) if connected in the circuit backwards or exposed to spikes above their voltage rating.


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    War is just a word used to hide the nakedness of their killing ......

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