Easy question--i should know this by now

[jimbob]

i should know this by now but i never use ceramic caps. How do you read these damned things?

example=NPO
              221j
              100v

or=  56
       kck

or= 471j

or= 561sqs

i think the 1st one is 220 pf?
next is 56pf
next is  470 pf
next 560 pf

this sound about right? Im guessing most all ceramic will me "pf" As far as the letters=no idea..I can tell the 100v is 100volt..

anyway,

thanks,

jim

[Yuan Han]

yeap it is correct....

i think caps are all labelled in pF unless they put uF or something
\
The values are correct.

I have no idea for tolerances and all though.

[Mark F]

NPO is the temperature coefficient. There is a page somewhere that explains them but I can't remember where. Do a search & you should be able to find it. This has come up in the past.

[petemoore]

Yupp, I think that's about right.
 Seems like you can tell from the size of same looking caps what the multiplier proabably is...
 Then I stick 'em in an input of a FF or something, and can usually get the ballpark from that, and the numbers start to make more sense with the context of the highpass filter test results.
 The same test could be done in HF rolloff cap position [signal to ground] at the end of a Fuzz.

[travissk]

Yes, you're correct. A slightly extended explaination to people who are new to the hobby and wonder how "471" turns into 470pf:

Capacitor value codes are two or three digits.

For two digits, it's that value in picofarads. For instance, "10" would be 10pf.

For three digits, the first two are the base value, and the third is a multiplier: a cap with code XYZ will have value
XY * 10^Z

So, to use one of your examples
221j = (22*10^1) pF = 220pf

The J is the tolerance code. It's +/- 5%. I had to look that up, and found this page which explains things better than I can . My rule-of-thumb which may not be valid is that a the letters increase, the cap gets less exact. Here's that page:
http://www.ee.washington.edu/circuit_archive/capacitors.html

Another  example:
472j = 47 * 10^2 = 4700pf
+/- 5% tolerance

[Leandro]

The only thing I can add is that if a number on a cap has only two digits and no units, it is usually nF (for example, the marking "10" is 10 nF).

Also, underlined numbers with no units are also usually nF (for example, "120" is 120 nF).

[casey]

here's a nice chart that i use....

http://www.garrettelec.com/catalog/TECHcatpgs.pdf

i hope this helps.

[jimbob]

great chart! Ill use it.


thanks all

jim