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Wikipedia explains the basics about the markings of capacitors, here. It lacks many markings most of which confuses me:

Ceramic brown-yellowish cap

  • 104 K5K (small ) --- what is the end "5K"? (Cannot be 5 kelvin as operating temperature!?)
  • 10 (box box, perpendicular right upermost corner) 35+ (Tantalum Cap, bigger variant of the last one
  • 154 C1K (what is C1K, some other notation to Wikipedia?)

Orange Ceramic

  • 333 K5X (what is 5X? X roman numeral?)

Brown Circle Slit

  • 10n (no other marking, what is the op.temp?) (Diameter: 7.5mm)
  • 27J 100V (what is 27J?) (Diameter: 4.9mm, blackdot on the head)

Blue Slit Square

  • (triangle) 104K X7R50 (What is triangle? X7R50? Operating V?) (side = 4.9mm)
  • 104 (side = 2.6mm, op.V? Tolerance?)

Questions about the bracketed

  1. How to know operating V without its explicit marking?
  2. What do the symbols, such as squares, plus-sign and triangle, mean?
  3. Can you evaluate the operating voltage from the size of the capacitor in the case when no marking or poor marking is given?
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Generally there are two labels on most caps.

The first is the value, which is written:
<Digit><Digit><Exponential Notation>
It's generally in picofarads.

The second is the TempCo, or Temperature Coefficient. There are two common specification systems, namely EIA Class 1 and Class 2. This is the mysterious second label in most cases. It's generally written:
<Letter><Number><Letter> (though there are a few variations)
There are a few common tempcos - NP0/C0G, X7R, X5R, Y5V, Z5U

Tantalums, and bigger ceramics often also have the voltages:
<voltage number><+ or v>

Therefore:

  • 104 K5K (small )
    The value is 10e4, or 100,000 pf / 0.1 uF. The tempco is not standard, may be manufacturer specific/extended range.

  • 10 (box box, perpendicular right upermost corner) 35+ (Tantalum Cap, bigger variant of the last one)
    Need a picture to be more specific, it's very likely a 35v rated cap, from the 35+.

  • 154 C1K (what is C1K, some other notation to Wikipedia?)
    Capacitance is 15e4, or 150,000 pf / 0.15 uF. Looks to be a Class 1 dielectric from the C1K. Is this a large cap? the tempco is very good.

  • Orange Ceramic 333 K5X (what is 5X? X roman numeral?)
    33e3, or 33,000 pf / 33 nF. Tempco is either manufacturer specific, or incorrectly read.

  • Brown Circle Slit 10n (no other marking, what is the op.temp?) (Diameter: 7.5mm)
    10n very likely means 10 nf, or 10,000 pf. If it's ceramic, it's probably 50v. Likely a cheap part, if the voltage is not marked.

  • 27J 100V (what is 27J?) (Diameter: 4.9mm, blackdot on the head)
    Voltage rating is self evident. J is the multiplier, and I think there is a standard for letter multipliers, but I do not remember where to find it.

  • Blue Slit Square (triangle) 104K X7R50 (What is triangle? X7R50? Operating V?) (side = 4.9mm)
    10e4 is the value - 100,000 pf / 0.1uF Tempco is X7R. the 50 is likely the voltage rating.

  • 104 (side = 2.6mm, op.V? Tolerance?)
    10e4 - 100,000 pf / 0.1uF. Voltage is not known

This is kind of a guess. Anyways, it should show how this sort of thing works. Older parts may vary wildly, and it's always just a guideline. The best thing to do is find the cap's actual datasheet.

A lot of the parts have unusual tempcos. Is this a automotive/extreme duty part which contains these components?

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Here's a staring point. If you know the type of capacitor that you have, but not what the value is, have a look at (for example) Farnell website and search for that part type. Then you can get a data sheet which usually explains things nicely.

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  • 1
    \$\begingroup\$ Could you please post real links! \$\endgroup\$ – starblue Jun 8 '10 at 19:24
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The "K5K", "K5X", "C1K" that doesn't match a temperature characteristic (X7R, NPO, C0G, etc.) is a manufacturer-dependent part marking to make use of the limited space available on the part.

If you look at some of the major manufacturers' datasheets for radial-lead ceramic capacitors, you'll see the following. Capacitance tolerance codes seem to be consistent, but otherwise there is some disparity.

  • Murata:
    • First character = capacitance tolerance (C = +/-0.25pF, D = +/-0.5pF, J = +/-5%, K = +/-10%, M = +/-20%, Z = +80%/-20%)
    • Second character = voltage rating (2 = 25VDC, 5 = 50VDC, 1 = 100VDC, 4 = 250VDC, 9 = 450VDC, 7 = 630VDC)
    • Third character = temperature characteristics (A = C0G, C = X7S/X7R, F = F/F5V, 8 = X8G/X8L, 7 = X7T)
  • AVX:

    • First character = temperature characteristics (A = C0G, C = X7R, D = X5R, E = Z5U, F = X8R, )
    • Second character = voltage rating (Z = 10VDC, 5 = 50VDC, 1 = 100VDC, 2 = 200VDC, 9 = 300VDC, 8 = 400VDC, 7 = 500VDC)
    • Third character = capacitance tolerance (C = +/-0.25pF, D = +/-0.5pF, F = +/- 1%, G = +/-2%, J = +/-5%, K = +/-10%, M = +/-20%, Z = +80%/-20%)
  • KEMET: unclear, first character is sometimes a "K" for KEMET; they use the same capacitance tolerance codes as AVX, but seem to mark with the full text of the voltage rating and temperature characteristics where possible.

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2. About "+"-sign

The plus means "polarised", the source is tronixstuff's site, point "Tantalum capacitors".

More here.

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  • \$\begingroup\$ Why did you not take the time to just comment on his. This is something you got because of his answer, he should be rewarded. \$\endgroup\$ – Kortuk Jun 10 '10 at 15:32
  • \$\begingroup\$ Kortuk: Yes and I am not taking credit of it, please, see the "the source is --". I think it is better to consider each point separately well in an answer rather than tell everything you know on a one big answer. Anyway, it is not identical it evolved to a next question which I think is now much easier to read than reading jammed comments. \$\endgroup\$ – hhh Jun 11 '10 at 21:05
  • \$\begingroup\$ Kortuk: cannot see a reason why you're pointing these things? There are still many points answered in 1-3. I will attack them soonish if there is no-one else to attack them. I call it self-learning and I think it is a good thing. Tronixstuff's article is just an introduction and did not cover all of points in the question. \$\endgroup\$ – hhh Jun 11 '10 at 21:07

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