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I have some capacitors that I cant figure out the value ( in farads {pf,nf,uf ect...}) Here are what they say: (each space shown here is a line down on the capacitor)

capacitor #1

103M Z5U 2-3KV ARC GAP KAP CHINA

capacitor #2

NPO 7.5D IKV

Capacitor #3

CM 1000M 125L

Capacitor #4

271 2KV

Capacitor #5

Z5U 4700M IKV

I am still sort of a beginner in electronics, and am only 13, so any information would be great!

Edit- I have a few more caps

I have couple more capacitors, can anybody tell me the value in farads? (pf, uf ,nf)

1

Y5F 221k 2kv

2

CM Z5U .1M 100v

3

20 underlined (I am guessing this is 20nf)

4

On frontside- 680 K

On backside- 74-16

Any answer would be great, even if you only know a few of them

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  • \$\begingroup\$ On number 3, capacitors are almost never reported in nF. I don't know if it wasn't in common use back in "the day" or it's somehow hard to record, but you will see 1000 pF or 0.0047 uF before you see 1 nF or 4.7nF. \$\endgroup\$
    – Austin
    Oct 20, 2015 at 17:50

4 Answers 4

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Common tolerance codes for capacitors: J = ± 5%; K = ± 10%; M = ± 20%.

Common value code for capacitors: Two numbers, and a third number c, where c tells you the number of zeroes behind the first and second number. Usually, the result is to be read in pF.

Sometimes, there's also a value expressed in pF or µF, and you have to guess which is right. Some examples:

  • A ceramic capacitor with the number "470" on it likely has 470 pF, because ceramic caps are still mostly used for small-ish values.

  • "0.47" doesn't make sense in pF, because 0.47 pF would be too small for almost any practical use, so pretty much all capacitors labeled "0.47" will have a value of 0.47 µF = 470 nF.

  • "470" on a large-ish film or electrolytic capacitor will likely mean the cap's value is 470 µF.

(And even more strange markings do exist...)

Now, let's use your capacitors' markings as examples for this - here's what I guess:

  1. capacitor #1:

    103M Z5U 2-3KV ARC GAP KAP CHINA

    10 * 103 pF = 10 000 pF = 10 nF. M: ± 20%

    Z5U is the type of dielectric. This is a pretty creepy type of ceramic with huge tolerances over voltage and temperature.

  2. capacitor #2:

    NPO 7.5D IKV

    7.5 is a fairly uncommon value for a capacitor. Mostly, you find values from the E6 or E12 series, hardly anything else. However, 7.5 is part of the E24 series, so it is not entirely alien, and according to this source, D would mean you have a tolerance of ± 0.5 pF. NP0 is a very good type of ceramic mostly used for values below 10...100 pF (that 0 in NP0 is a zero; I remember to have read that NP0 means negative-positive-zero, i.e. nearly zero tolerance over temperature and voltage changes). I guess your cap has 7.5 pF. That I is likely a 1, meaning the maximum voltage for this cap is 1 kV.

  3. Capacitor #3:

    CM 1000M 125L

    Maybe 1000 pF = 1 nF, with a tolerance of ± 20 % (M).

  4. Capacitor #4:

    271 2KV

    27 * 101 pF = 270 pF. Maximum Voltage: 2 kV.

  5. Capacitor #5:

    Z5U 4700M IKV

    Another one with a cheap type of ceramic (Z5U), probably 4 700 pF = 4.7 nF. Tolerance: ± 20 % (M). Max. Voltage: 1 kV.

Again, this is guess-work. Unfortunately, there is no standard that all manufacturers adhere to, so to be exactly sure, you would have to measure your devices and find the original data sheets with the device marking specifications, which can be very, very annoying.

Even more examples from similar questions: Identifying Capacitors, https://electronics.stackexchange.com/questions/10474/what-kind-of-capacitor-is-this

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  • \$\begingroup\$ thanks, I don't have an original data sheet because I just got a pack of different capacitors at goldmine electronics. It was cheap, because you don't know what your getting. \$\endgroup\$
    – skyler
    Jun 7, 2012 at 21:14
  • \$\begingroup\$ Ha, electronic components priced by the kilogram (or pound). This is how careers start. My home lab still has many parts I got exactly this way (others were taken from junk PCBs, some were of course bought). Seriously, learning about real components like you do now will prove to be a very big advantage if you're heading towards electronic developing as a job, later on. There's nothing like practical knowledge and experience paired with the theory you're taught in school or college. Hacking alone will get you only so far, and theory alone will never be a good product. If you have both - great! \$\endgroup\$
    – zebonaut
    Jun 8, 2012 at 11:15
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    \$\begingroup\$ NPO (C0G) are available for values up to 100nF for applications up to 100V. datasheets.avx.com/C0GNP0-Dielectric.pdf \$\endgroup\$
    – Peter Smith
    Jun 23, 2016 at 10:54
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Note that there are now incredibly inexpensive gadgets (on Ebay, etc.) which measure resistance, capacitance, inductance, identify and test semiconductors (diodes, transistors, FETs, SCRs, etc.) And all for < $15. Highly recommended for identifying and testing surplus or otherwise "mystery" components. A search for key words like

transistor tester diode triode capacitance

will show dozens of options at various prices. Highly recommended.

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  • \$\begingroup\$ Do note, short capacitors before connecting tester, then remove short and test. Don't ask how I learned this... :) \$\endgroup\$
    – rdtsc
    Jul 30, 2020 at 21:41
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Case 4 is the common code in use today, which is a floating point format. The first two digits are the mantissa, the last digit the power of 10, with the whole thing in pF. 271 therefore means 27 x 10^1 = 270 pF.

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    \$\begingroup\$ I bet you scared him with floating point and mantissa. He's only 13 :-) \$\endgroup\$
    – m.Alin
    Jun 7, 2012 at 20:18
  • \$\begingroup\$ @M.Alin: I don't check the credentials of everyone posting a question, so didn't realize that. I'd go back and add more introduction to the concept, but zebonaut has already provided a detailed answer. \$\endgroup\$
    – Olin Lathrop
    Jun 7, 2012 at 20:26
  • \$\begingroup\$ @m.alin: I just checked the OP's profile, and it says nothing about his age, 13 or otherwise. \$\endgroup\$
    – Olin Lathrop
    Jun 7, 2012 at 20:27
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    \$\begingroup\$ He mentions his age in his question.. \$\endgroup\$
    – m.Alin
    Jun 7, 2012 at 20:28
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A better answer for a 13-years old, in my opinion, is:
search "identify capacitor code" on Google.

He could found a lot of link like this or this that can help him learn how to solve similar problems; we sould teach our kids how to help themselves.

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  • \$\begingroup\$ The OP isn't 13 years old anymore since you answered this question four years late. Now he's at least 17, so a junior or senior in high school. \$\endgroup\$
    – Olin Lathrop
    Jun 23, 2016 at 19:46
  • \$\begingroup\$ No! I do not think that he will go to the college, we have spoon-fed him, we ruined a young mind ... :-D The question is why this "ask" has emerged after years. \$\endgroup\$
    – Antonio
    Jun 24, 2016 at 10:36
  • \$\begingroup\$ ... Also, my own answer isn't just giving the results, I have also tried to provide many hints on how I got there. Sure, you can also use a search engine, but when you're just starting off and are unsure about the context, what exactly do you type into the search engine? And why? \$\endgroup\$
    – zebonaut
    Jun 24, 2016 at 11:58

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