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I am trying to figure this cap out and locate a new one. It says 107K and 10K on it. Is is polarized ? what is it and where do i find one ?

enter image description here

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13  
According to this web page, that one is called "Clyde": sydlexia.com/imagesandstuff/pacman/ghosts.png – David Kessner Apr 13 '12 at 15:25
@Neil can you post a picture of it? Although capacitor codes come in a ###X format, the numbers 6 and 7 is never used on the third digit or multiplier. 107K is an invalid code. – shimofuri Apr 13 '12 at 15:29
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@shimofuri: ??? Kemet and other manufacturers of tantalum and large ceramic capacitors do it all the time. "107" = 10 * 10^7 pF = 100uF capacitors – Jason S Apr 13 '12 at 16:19
I don't know why the upper "K" is there; it doesn't correspond to Kemet's capacitor marking specification. But the lower K with the bars is the Kemet trademark, and if the upper K weren't there, the rest of the markings would match the Kemet capacitor marking specification. – Jason S Apr 13 '12 at 18:23
Aha, here we go: the upper "K" indicates a special order 10% tolerance. If you look at the image from the Kemet catalog I posted, it says "CAPACITANCE TOLERANCE M = ±20% (K -- 10% Special Order Only)". The K is a standard capacitor code for 10% tolerance (J = 5%, M = 20%) – Jason S Apr 14 '12 at 2:14
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4 Answers

up vote 11 down vote

It's a 10V 100uF 3-leaded tantalum capacitor from Kemet (T396 series -- see Kemet's website and TTI). The "K" with the bars above and below is a trademark of Kemet. The yellow encapsulation and the stencil font of the numbering are consistent with Kemet capacitors as well, but I can't say for sure whether other companies have copied them.

Their circuit diagram shows two ground leads, presumably to reduce ESR and inductance (although it seems like if you really want to reduce ESR and inductance you should use a surface mount capacitor)

Aha, this is what they say about the three-lead design:

The three-leaded design (the anode is in the center) enables operators to insert the capacitors into printed circuit boards correctly without having to visually determine polarity. This timesaving device also eliminates board damage that may result from incorrect insertion.

enter image description here

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"enables operators to incert (sic) the capacitors into printed circuit boards correctly without having to visually determine polarity". This can't be serious. Components are made to be mounted by a pick and place machine, which doesn't need to visually determine polarity. – stevenvh Apr 13 '12 at 16:36
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Perhaps you are forgetting that through-hole components come from an age when pick-and-place machines were less common. The "incert" misspelling was my fault, not Kemet's, and I have corrected it. – Jason S Apr 13 '12 at 16:47
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Also, for what it's worth, the penalty for installing tantalum capacitors backwards is very bad -- they can self-ignite and damage the board they are installed on. – Jason S Apr 13 '12 at 16:55
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It remains a strange argument. It's more costly like I said, and common (2-pin) capacitors have different length leads to ensure proper mounting. – Federico Russo Apr 13 '12 at 16:56
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So... what are we arguing about exactly? I believe I have identified the part that Neil posted in his question. I don't use tantalum capacitors in my designs and would be unlikely to ever want to use this 3-legged "feature" myself. – Jason S Apr 13 '12 at 17:00
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up vote 4 down vote

Nope, I think stevenvh is right. It's a ceramic resonator.

OK, I have changed my mind again after seeing Jason's answer. This is the reason Murata give for their three terminal capacitor.

Three terminal capacitor

According to Murata, they are used when you want a decoupling capacitor with greatly reduced effective series inductance.

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up vote 3 down vote

This looks much like the dual capacitors found in this discussion thread.

Here's a picture:

enter image description here

I would argue that they're non-polarized ceramic capacitors.

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I would tend to agree with this, it even has the things labeled with C1 and (presumably) C2, though I never did see these things before personally. – hak8or Apr 13 '12 at 15:44
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They're tantalums, not ceramics, and they're not dual capacitors; they have 3 leads. But the ones you posted a picture of are from the same series: they are Kemet 47uF and 33uF tantalum capacitors from their T398 series. The K with the bars is a giveaway. – Jason S Apr 13 '12 at 16:51
@JasonS Appropriate strikethrough applied. – Madmanguruman Apr 13 '12 at 17:37
well... technically they are polarized capacitors, it's just that the "+" terminal is in the middle and the two "-" terminals are at the ends. But +1 for the picture because having two photos (and three capacitors) to find a pattern from, was much easier than just the one posted above in the question. Thanks! – Jason S Apr 13 '12 at 18:22
noted. and struck. – Madmanguruman Apr 13 '12 at 20:02
up vote 2 down vote

From the three pins I'd say a ceramic resonator, and then the 107K reminds me of the 10.7MHz intermediate frequency in FM receivers. Resonators have their frequency as marking. So probably a 10.7MHz resonator. (Though in receivers crystals are more used than resonators, because they're more precise and more stable)

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