Capacitor color codes

[zachtheterrible]

Hi everybody. I inherited about 300 capacitors when i moved into a new house and they're all color coded therefore nearly useless 2 me. I used this calculator on a site to tell me the value of a capacitor, but I think something is not matching up. Here's the color code for one capacitor, could someone kindly tel me wut it is?:

Top: Orange
Middle: Red
Botom: Yellow
Very bottom (underneath the cap): Black
On the side, runs about halfway down the capacitor: A line of green

These capacitors are from back in the day, the 70's i think. Are they still good? Some of them have a little rust on them, but overall they're in pretty good condition.

also could someone tell me what kind they are? I think they're tantalum.
thank you very much

 

[zevon8]

Without seeing one it is hard to say what kind they are or materials they are made from. If they look like a piece of gum you get in a foil cover blister pack like Dentene, ( pillow shapped )they are not likely tantalum, but polystyrene or mylar film, maybe mica. Most of the tantalum ones look like a Tic-Tac.

Cap color codes are a whole world of fun. Yours seems to be 0.32uF, 100V 20% tolorance.

orange = 3
red = 2
yellow = 0000
green = 100 V
black = 20%

values are labelled in nF, so 320,000nF = 320pF = 0.32uF

Here is a page that has some of the more common shapes and codes.

**broken link removed**

They may be just fine, who knows, you would have to try one to see.

 

[zachtheterrible]

well it looks like that little calculator was right. thanx

 

[panic mode]

values are labelled in nF, so 320,000nF = 320pF = 0.32uF

this must be a typo so just to straighten record:
capacitors are labeled in pF (smallest practical unit,
greater values are achived by means of multiplier 1x, 10x, 100x etc.).
in other words 320000pf=320nF=0.32uF=0.00032mF=0.00000032F

Note that it's quite common with capacitors that rings "melt"
together. 320nF is unusual value. It's hard to tell without seing
the part but I wouldn't be surprised if this is actually
orange (3)
orange (3)
red (x100)
etc making it 3300pF or 3.3nF (black bottom is probably just color
of the body).

:?

 

[Dean Huster]

The color-code site that was posted was taking too long to load at my 26.4KB/s so I may be repeating something.

You've perfectly described an older conformal coated (dipped) tantalum capacitor. They've since discarded the code in favor of the "105M" style of marking.

Holding the cap with the leads pointed downward:

The top color (tip) is the first digit; the second color is the second digit; the third color is the multiplier. All three bands work just like the resistor color code, the value ending up in picofarads. So a BRN-BLK-BLU scheme yields 10,000,000 pF or 10µF. The multiplier band is usually limited to YEL, GRN, BLU and VIO since these are tantalum electrolyics.

The color swipe down the side is very important because it's a dual-purpose band. It marks the positive lead of the cap and it also represents the voltage rating according to the following list:

BLK = 4v
BRN = 6v
RED = 10v
ORN = 15v
YEL = 20v
GRN = 25v
BLU = 30v
VIO = 35v
GRY = 50v

In addition, there might be a little gold or silver dot on the very tip (you don't see this often) that overrides the assumed tolerance of ±20% for a ±10% tolerance (silver) or ±5% tolerance (gold).

Dean

 

[zachtheterrible]

There is no way that its orange orange yellow. it is VERY clear, the lines are not blured @ all. i think dean n zevon are right.

I dont know if this actually means something or not, but on the very bottom of the cap, there is a thin black line that runs from one lead to the other lead of the cap.

thanx, this is an extremely big help :lol:

 

[panic mode]

zach,
it's time to build a capacitance meter

 

[zevon8]

values are labelled in nF, so 320,000nF = 320pF = 0.32uF

this must be a typo so just to straighten record:
capacitors are labeled in pF (smallest practical unit,
greater values are achived by means of multiplier 1x, 10x, 100x etc.).
in other words 320000pf=320nF=0.32uF=0.00032mF=0.00000032F

Yes, mea culpa, too early in the AM, and a distinct lack of caffeine.

Also, I should have said polyester film, not polystyrene. I would agree, it does not follow the standard value spacing, and 330 would make more sense, but who knows. Telco equipment has all sorts of custom value caps for example, so i guess economies of scale apply.

 

[zachtheterrible]

values are labelled in nF, so 320,000nF = 320pF = 0.32uF

in other words 320000pf=320nF=0.32uF=0.00032mF=0.00000032F

we all agree taht the calculation comes out to .32uf (even though some calculations were a bit off) . . . im gonna stick w/ that, and like zevon8 mentioned there are all sorts of custom value caps. Someday i'll make me a cap meter. Ive got so many other things i wanna do first though

i oughta rename the subject of this page "the capacitor caper" :lol: . . . pretty lame eh?

 

[chemelec]

Hi Zack, If you connect a 100K Resistor in Series with that Capacitor.

A 320 pF Cap has a Capacitive Reactance of about 10 Meg ohms.
A .32 uF Cap has an Capacitve Reactance of about 10 K ohms.

Now Put your Digital Voltmeter On an AC Range, and across the Cap.
Now Apply 110 Volts AC across the Series Resistor and Capacitor.

If the Cap is a .32 uF, your voltmeter will read about 9.5 Volts AC.
If the Cap is a 320 pF, your voltmeter will read about 109 Volts AC.
THAT ASSUMING YOUR 110 Volts IS 110 VOLTS.
It may be up to 120 Volts.

DON'T GET A SHOCK.
BE CAREFUL IN DOING THIS!

But you get the Idea, I HOPE.

Take care.........Gary

 

[Dean Huster]

Uh, Gary, I don't much like your method of determining the cap value. First, these caps aren't rated at very high voltages, so doing this with the 120v mains voltage could easily wreck the cap -- and tantalum caps are especially sensitive to over-voltages and reverse polarity. Second, being the mains voltage, if the cap does go bad, it'll go out with a dangerous bang and could do some bodily damage.

The idea is good if you use the sine wave output of a function generator or an audio oscillator. The lower voltage and power is safer for the operator and the parts. In addition, you can change the frequency to allow more reasonable voltage readings without using resistors of extremely high values which can in turn give you funny readings because of meter loading.

I was surprised at the mention of telco parts often being custom. I never did understand why a telco capacitor would have a value of 0.02383µF with a tolerance of 5%. The math doesn't hold up very well, does it?

Nearly all caps do have standard values and I, too, regardless of how definitely the colors appear to be orange and red, would doubt the 0.32µF vs a 0.33µF. On these conformal coated tantalums, they often would shift a color a bit so that you could tell that there were two digits shown. That way, you wouldn't have to wonder if the first and second bands were duplicates or the second and third bands were duplicates, which would make a tremendous difference in the value.

The 24 standard values are 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82 and 91. These are the standard values for 5% resistors. Every other one (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82) are for 10% resistor values and every other one of those (10, 15, 22, 33, 47 and 68) are for 20% resistor values. Capacitors tend to use the 20% standard values even though they may have tolerances of 10%, 5%, 2% or even 1%. Usually a cap is used with a resistor for some kind of timing or frequency-determing network and selecting the cap and then trimming out with a tight resistor is cheaper than stocking all kinds of standard value caps.

Dean

 

[zachtheterrible]

i dunno gary, this sounds a little scary :shock: . heheheh. dont want any caps blowing up in my face :shock: . Maybe I'll hide under the table w/ my voltimeter and plug in the mains with the capacitor on the top of the table. :lol:

since i don't REALLY need these caps, maybe ill wait til the day i decide to make myself a capacitance meter. meantime, ill just order the ones i need.

 

[chemelec]

1) There was a Mention that these were 100 Volt Caps. If that is so, the 110 volts through a 100K Resistor Will NOT Burn them out in a Quick test.
The 100K Resistor Limits the Current to 1.1 Ma, Not Much Current a all.

2) I did a 10 Second Test with a .1 uf, 35 volt Tantalum, No Problem. In 10 Seconds, The cap could Not Explode with this low current.
But Even if it did short out, it is protected from excessive current by the 100K Resistor and because any failure in this test would result in a Shorted cap, it would be Easily Tested afterwards with just an Ohm-Meter.

3) As To Tantalums, I HIGHLY DOUBT that anyone make Tantalum capacitors of the values you have stated. Sounds more like a Silver Mica.
Besides, 320 pF Tantalum, Highly Unlikely!

4) A Signal Generator, using lower voltages and other values of Resistors are Fine, But DOES "ZACH" have a Signal Generator? And Does he know how to Calculate Capacitive Reactances in a Voltage Divider with a Resistor?????

5) I Just tried to give him a SIMPLE TEST. And It was Tested by me and it Does Work.

6) I would assume Zach has at least a Basic Multimeter.
If he had a Signal generator and a Know inductor, He could also do a test for Resonance. But does he have any Equipment?

SORRY, WAS JUST TRYING TO HELP.