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Post by flateric on May 28, 2010 14:23:58 GMT -5
I got these tant caps (2.2uF) for a Small Clone chorus build.  Now Tantalum caps are supposed to be polar, right? One leg + the other -ve, but I don't know which way round these should sit as there's no other marking on them. I'm assuming if I get it wrong the circuit won't work. Any advice please? |
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Post by newey on May 28, 2010 18:40:16 GMT -5
Probably not. And these things can fail spectacularly when cross-polarized, although there's probably not enough current in a pedal to do that.
The rule of thumb is that the positive leg is always longer. Yours appear equal, although it's hard to tell from the photo. Is it possible this one was snipped from a board in a prior life?
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Post by sumgai on May 28, 2010 19:26:11 GMT -5
♭eric,
One of the advantages of tantalum caps is many, if not most, of the small-value caps are non-polarized. newey's advice above is right, providing the manufacturer played ball with the rest of the team. Your unit looks to me like it falls in the non-polarized camp, so you should be able to connect it up in either orientation.
HTH
sumgai
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Post by newey on May 28, 2010 20:36:33 GMT -5
I was assuming his build called for a polarized cap; he can't just substitute a non-polarized one, correct?  |
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Post by flateric on May 29, 2010 1:44:20 GMT -5
yes, theres a + sign indicated on the circuit for the cap and the parts list calls for a 2.2uF Tantalum. (Tonepad.com Small Clone Chorus tonepad.com/getFile.asp?id=97) top left. I got a pack of 5 of these and they all have same leg length and markings. |
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Post by sumgai on May 29, 2010 17:26:24 GMT -5
I should find a link to somewhere that gives all the gory details, but in essence, the reason for those polarity markings is that, once upon a time, the only way you could get such high values was by using a polarized electrolytic cap. Such designs were first brought out well before tantalum caps were invented/discovered/uncovered/thought up..... Suffice it to say, in audio circuits where we want to pass (or bypass) the lowest two octaves, values between 1 and 20µfd are common, and wherever you see these values, a non-polarized cap will do the job, tantalum or otherwise. So why do you still see polarity markings? Because that's how we did it in the old days, and there ain't nothin' wrong with that, bunky!  No, seriously...... There're only two reasons to specify a polarized cap (in an audio circuit): either you've copied someone else's design from yesteryear, and you have no real idea what the underlying principles are, or else you've got a junk-bin full of such componentry, and since it worked when you tried it...... well, I suppose you can't be faulted for wanting to lead others to get the same results, so you can be excused for including the polarity sign(s), because once again, you don't truly understand what's under the hood. But if you were truly up-to-date on your design data, and had a good source of parts to hand, you'd specify non-polarized caps, have the schematic(s) and the circuit boards marked as such, and walk away happy. ;D Googling for more detailed info is an exercise best left to the Nutz.  HTH sumgai |
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No, seriously...... There're only two reasons to specify a polarized cap (in an audio circuit): either you've copied someone else's design from yesteryear, and you have no real idea what the underlying principles are, or else you've got a junk-bin full of such componentry, and since it worked when you tried it...... well, I suppose you can't be faulted for wanting to lead others to get the same results, so you can be excused for including the polarity sign(s), because once again, you don't truly understand what's under the hood. But if you were truly up-to-date on your design data, and had a good source of parts to hand, you'd specify non-polarized caps, have the schematic(s) and the circuit boards marked as such, and walk away happy. ;D