Saturday, December 24, 2011

How to Remember the Resistor Color Code

The resistor color code is used to distinguish resistors with different amount of resistance (Ohms). There are some alternatives to interpreting the value of a resistor with the color code, but they involve money, and a lot of time. I will present to you a strong strategy for quick memorization of the whole table (color code table).

How To Memorize The Color Code

1. The Color of DIGITS Of The Resistor (the 1st two bands)

If this is new to "roy"-"G"-"biv" than maybe this will be more helpful:


ROYGBIV is an acronym used to describe the colors of a rainbow in order. It is not pronounced letter by letter, because that takes a lot of energy. Instead people say "roy-gee-biv."

roy like "SOY" but with an R instead of an S.
gee like "G" (Ganster) or "Oh, Gee"
biv like "give" with a b in the place where the g in "give" is.

Can you locate Roygbiv on the color code chart? 
A Color Code Chart (Diagram)

Roygbiv is hiding below the brown rectangles with a 1 in them in perfect sequence besides indigo.
Sadly, Indigo got pushed in with blue so you must exclude that color from the color code pattern. The reason indigo is excluded is because it is indistinguishable when painted on tiny tiny resistors.

R(2) O(3) Y(4) G(5) B(6) V(7)

_?_(0)  _?_(1)  R(2) O(3) Y(4) G(5) B(6) V(7) _?_  (8) _?_(9)

The next part of memorizing the digits is filling in the first 2 numbers, zero and one, and the last two, gray and white. Memorizing gray and white is a cinch, just remember when you are very old you will grow gray hair, but years older than that you will grow white hair. Since there are that final two values it is well suited for the final two hair colors of life.

_?_(0)  _?_(1)  R(2) O(3) Y(4) G(5) B(6) V(7) GRAY(8) WHITE(9)

Now knowing that white is 9, because the 90 year old has white hair, you must think back to a more youthful haircut, black and brown. Black comes before brown in the alphabet, thus black is assigned the value (0) and brown the value (1).

BLACK(0)  BROWN(1)  R(2) O(3) Y(4) G(5)   B(6)  V(7)  GRAY(8) WHITE(9)

The 10 possible digits of a decimal system (0,1,2,3,4,5,6,7,8,9) are all assigned one particular color so all decimal type numbers can be created by utilizing the combonation of the first and second band of the standard 4 band resistor. 
Example of digit combinations (there are 100 total): 00,01,02.... 32, 33, 34....69, 70, .... 99.

In combination with the first two bands (from left side) the multiplier can create numbers like, 1000, 500000, 44000, 230000. 

2. The Multiplier
The multiplier value can be determined by utilizing the steps shown above and knowing that the multiplier is simply a base 10 number ranging from 1 to 1 * 10^(3rd band color value) =10000000

Multiplier = 1 * 10^(3rd band color value)
Resistance = [first two digits]* 10^(3rd band color value)

3. Practice 

The last band of a 4-band resistor is much less important for anyone first learning the code, but basically the code for tolerance is either NONE (tan) or Silver or Gold.

None = +-20%
Silver = +-10% 
Gold = +-5%

Other Resources For You!
If you enjoy this post, you may like How To Organize Resistors.


Anonymous said...

Cool post. It all looks right too.

Power Resistors said...

Great over view on the resistor color code.

Brian said...

Thank you! I appreciate your support