Page 414 - Robot Builder's Bonanza

FIXED RESISTORS 383

Table 31- 1 Resistor Color Code Chart

Color 1st Digit 2nd Digit Multiplier Tolerance
Black 0 0 1 —
Brown 1 1 10 1%
Red 2 2 100 2%
Orange 3 3 1,000 3%
Yellow 4 4 10,000 4%
Green 5 5 100,000 0.5%
Blue 6 6 1,000,000 0.25%
Violet 7 7 10,000,000 0.1%
Gray 8 8 100,000,000 0.05%
White 9 9 — —
Gold 0.1 5%
Silver 0.01 10%
None 20%

Table 31- 1. (For your convenience, the same chart is duplicated in Appendix D, “Electronic
Reference.”)
The first and second colors are the first and second digits of the value; the third color is the
multiplier, the number of zeros you need to add. For example, if the first color is brown, the
second color is red, and the third color is orange:

Brown = 1
Red = 2
Orange = Multiply by 1000 (the same as simply adding three zeros)
which gives you 12,000.
The fourth band in a four- band resistor is the tolerance, which is the amount (in percentage
form) that the resistor may actually vary from its printed value. For example, a silver band means
the resistor has a 10 percent tolerance; assuming a value of 12,000, 10 percent is 1200. That
means the actual value of the resistor can be anything between 10,800 and 13,200.

Note the in front of the tolerance values in Table 31- 1. That means or the indicated
percentage. It can go both ways.
So- called precision resistors have a tolerance of less than 1 percent. Generally, these have
G five or more bands. The color coding is the same, but the extra bands provide more accurate
numbers.
High- precision resistors are virtually never needed in the typical robotics circuits, and you
can basically forget about them. The information is provided here so you know about the
variations you can encounter when buying resistors new and as surplus.

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