 JasonLook ma, No brainsPremium,Mod
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Re: Ideas, Suggestions... Resistor Color Codes:
Those color-bands on a resistor are used to determine their value. (Measured in Ohms)
(I will add a couple pics tomorrow)
First: The "Magic Decoder ring"
Color - Value
Black - 0
Brown - 1
Red - 2
Orange - 3
Yellow - 4
Green - 5
Blue - 6
Violet - 7
Gray - 8
White - 9
Gold - 5%
Silver - 10% (more on this later)
Okay. On a resistor, it will typically have 3, or 4 bands. If theres 4, the 4th band should be gold, or silver. This is the resistors "Tolerance" The deviation from its stated value that would be allowed.
For instance, if the resistor is supposed to be 100 ohms, but has a gold (5%) band, it can be up to 5% different in either direction from its sated value. (95 Ohms, to 105 Ohms). A silver band indicates a 10% tolerance, and no band means 20%, (IIRC)
There are other colors of tolerance, but thats outside the scope of this write-up.
Now, with that out of the way, lets figure out how to read a resistor.
With the tolerance band on the right (4th band) starting at the left we have the first band. (First significant value), the second band (Second significant value) and the third band (Multiplier)
With the multiplier, simply add that colors # of zeros to the end of your first, and second significant vales.
Its a bit easier in example.
Lets take a resistor, we'll say its bands are Brown, Red, Yellow and Gold.
Starting at the first band: Brown = 1
The second band: Red = 2
The third band: Yellow = 4
So we have 124. But, remember the 3rd band is the multiplier If its yellow (4) it means to add 4 zeros to the end of the first 2 numbers. So 124, becomes 120,000, or 120K Ohm. With the gold tolerance band (5%) in reality, the resistor can be anywhere from 114,000, to 126,000 ohms (+/- 5%) and still be "within spec"
Lets try one more.
Yellow, Green, Black, Silver.
Yellow = 4
Green = 5
Black = 0
Silver = 10%
Heres a bit of a curve ball. The 0 for the multiplier is just that.. Add, zero zeros to the end of the first 2 numbers.
We end up with a resistor that is 45 Ohms. It can be anywhere from 40.5 to 49.5 ohms, and be in the rated 10% tolerance.
Why a tolerance?
Well, as much of a science as these things are to manufacture, the methods arent perfect. They can make resistors "Dead-On" but theyre quite expensive, and hard to find. Its a *lot* cheaper, and easier to make these (Specifically, Carbon-composition type) resistors with a built-in "fudge factor". Most consumer level resistors are in the 5% tolerance category, and most electronic circuits have no problem with this tolerance.
Ill add some pics tomorrow.
-Jason
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