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# How can I identify the values of recycled mylar and ceramic capcitors using the codes on the side? Answered

I have desoldered a couple of old radios etc. and am trying to identify all the components I have harvested.

Amongst them I have some green mylar caps. One such cap has the markings: 2A473J

I did a bit of research and found out that usually the first two numbers is the significant figures and the third is the number of zeros. Assuming its not counting the 2A, I'm guessing this cap is 47000pF or .047μF. and I found out that the J is +/-5% tolerance?

Firstly, is everything I have worked out/ assumed true and if so and the cap is .047μF, what does the 2A mean?

Others say 2A73J, 2A103J, 2A332J, 2A222J, 2A102J

Ceramic ones say 4, 22, 30, 33, 102, 103, 104, 203, 221, 222, 331, 332, 333, 473, 682, 683

And I also have 4 of another type of cap that I don't know the name of- they are shown in the 3rd picture.
the two smaller ones say 474 on, one say 8.0M and the other:16.93M

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## Discussions

When you've got three consecutive digits on a capacitor like that, usually the first two are a decimal number between 0 and 99, and the last digit is a multiplier and a power of 10, and the units for this number are in picofarads.

For example:  if you've got a capacitor that has 104 printed on the side, then this means 10 multiplied by 10 to the 4th picofarads

= 10*10^4*(10^-12 F)

= 10^-7 F = 0.1 *10^-6 F = 0.1 microfarads

As another example, 222 means 22*10^2  picofarads = 2.2*10^-9F

what do you think the '2A' means then?

and the third photo-they say 8.0M and 16.93M?

I don't know what the 2A means, when printed on capacitors.  I also don't know what a single A, or a J, or a K, means either.

The ones with a M suffix might be ceramic resonators,
http://en.wikipedia.org/wiki/Ceramic_resonator
in which case I think the M stands for "megahertz".

Yeah i've looked on various sites which tell you how to identify the values but none mention prefixes like 2A.

Nevermind- i'll just pretend it isn't there ;)

If you find a capacitor with just two digits on it, eg. 10, or 22, or 30. Usually that is just a value in pF, without any multiplier; i.e 10 picofarads, or 22 picofarads, or 30 picofarads, respectively.

Usually/often/ if you're lucky, voltage rating. Capacitor markings are one of electronics' most arcane subjects - second only to SOT23 component marking, in surface mount tech.....

So you think the 2A might be 2 volts?
Also I read that J is the tolerance??

No, its some code or other. J could well be tolerance.

These caps are at a minimum 50VDC.

I have seen some bypass disc caps rated as low as 12.5VDC
for 5V system ICs.

A