Capacitor Value

[dpeterson3]

I got a bag of capacitors from radioshack, but I am not sure how to read the values on them. Instead of having a three digit code on them, some only have 1 or 2 digits. Some have "10" on them and others have "7" on them. Does this mean missing 0's or something else?

These are all ceramic.

[MrForbes]

A real small one that says 10 might be 10 picofarad.

you probably paid a low enough price per capacitor that you can toss the ones you can't figure out...

[dpeterson3]

I like that idea. The only problem being that half the bag is like that. No more grab bags from radioshack.

[EricVanWyk]

This link might help: http://www.electronics2000.co.uk/cal...calculator.php

Sometimes they are labeled with that code, but not always.

[dpeterson3]

Thanks, but I tried that site already. It didn't recognize the values I put in. I am at a loss.

[dmcguire3006]

Quoted below from:
http://www.hackcanada.com/blackcrawl...ic/capinfo.txt

Capacitor Value Reading

Capacitors of these types (ceramic, various plastic films) are coded
in pF, the last two digits being the number of zeroes following the
first two digits.
e.g. 104 = 10 0000 => 100,000pF => 0.1uF.
The values are sometimes coded as colour bands on some types of caps.

The letter following the value is usually a tolerance code (IEC 62, BS1852):
C = +/-0.25pF D = +/-0.5pF F = +/-1% G = +/-2%
J = +/-5% K = +/-10% M = +/-20% Z = -20 +80%

The coloured end of single plate ceramic caps indicates the temperature
coefficient of the dielectric:
green = high K
yellow = medium K
red/violet = +100ppm/deg C
black = zero TC
brown = -150ppm/deg C
violet = -750ppm/deg C
brown/red = -1500ppm/deg C

There may also be a material code used for plastic films as follows:
MKT = Metallised polyester
MKC = Metallised polycarbonate
KT = Polyester film/foil
KS = Polystyrene film/foil
KP = Polypropylene film/foil
MKP = Metallised polypropylene

[dpeterson3]

My problem is I only have 2 numbers. The normal code has 3. Most of these caps only have 1 or 2 numbers on them. I am wondering if the other two can be assumed as 0 or what. They are ceramic, so there is no color code. There are no letters either. I have ai or 2 digits and that is all.

[DonRotolo]

That is correct, but he has caps with one and two digit 'codes'.

If they are physically small - say, the size of a lentil or smaller - that could be the actual value in picofarads.

A capacitance meter is $35, maybe someone you know has one you can borrow? I have one, but I fear a trip to NJ would absorb some of the savings...

[EricVanWyk]

Originally Posted by Don Rotolo

That is correct, but he has caps with one and two digit 'codes'.

If they are physically small - say, the size of a lentil or smaller - that could be the actual value in picofarads.

A capacitance meter is $35, maybe someone you know has one you can borrow? I have one, but I fear a trip to NJ would absorb some of the savings...

Some multimeters have (bad) capacitance meters built in.

Also, I love that you compared them to the size of a lentil.

[MrForbes]

If you want I'll send you my grab bag from RS from the mid 80s....no charge...they seem to be marked better.

[dpeterson3]

I found this webstie finally
http://www.ehow.com/how_4480564_lear...apacitors.html

specifically this paragraph

"Learn to read 2-digit capacitors. Ceramic disc capacitors are often labeled with just two numbers. if the value is less than one, these capacitors are generally measured in microfarads. If the value is more than one, it indicates a value in picofarads. For example, a capacitor that reads ".01" will have a capacitance of 0.01 μF (microfarads), or 10,000 pF (picofarads). A capacitor labeled "15" will have a value of 15pF."

odd. I ahve never heard this before. Thanks for all the help

[MrForbes]

I guess I should have explained better in my first post...oh well

[Al Skierkiewicz]

Originally Posted by squirrel

If you want I'll send you my grab bag from RS from the mid 80s....no charge...they seem to be marked better.

I have a bag like that! Wanna trade?
Although the two digit code represents picofarads below 100, don't be fooled by a marking that is obscured or rubbed off. Use a bright light and if the cap is dipped in parafin, the last digit might be under a drip.