Direct Current and Transient Analysis 141
The value of an arbitrary color-coded resistor R is specifi ed by the following rules:- The fi rst (A) and the second (B) band represent the fi rst (A) and the second digit (B),
of the value R. - The third color band (C) represents a multiplication factor of 10 raised to the power
C (10C ), with unit ohms (Ω). - The fourth band (D) gives an index of the manufacturer’s tolerance given by [±(AB) *
10 C (^) * D].
- The fi fth color band (E) gives an index of the manufacturer’s component reliability,
which represents the probability of failure of R per the fi rst 1000 hours of use.
The nominal value of an arbitrary color-coded resistor R is given by
R = (AB) * 10 C
The tolerance of the resistor R would be bounded by
{(AB) 10 C − (AB) 10 C (^) D} ≤ R ≤ {(AB) 10 C + (AB) 10 C (^) D}
Finally, the reliability of the resistor R is given either by E or E%, and that quantity indi-
cates the probability of failure of R during the fi rst 1000 hours of usage.
For example, let a resistor R be defi ned by the following color bands:
Band 1 = Brown (A)
Band 2 = Black (B)
Band 3 = Orange (C)
Band 4 = Silver (D)
Band 5 = Brown (E)
TABLE 2.2
Band 1
(First Digit)
Band 2
(Second Digit)
Band 3
(Multiplying Factor)
Band 4
(Tolerance)
Band 5
(Reliability)
Brown = 1 Black = 0 Silver = − 2 Gold = 0.05 Brown = 0.01
Red = 2 Brown = 1 Gold = − 1 Silver = 0.10 Red = 0.001
Orange = 3 Orange = 3 Black = 0 None = 0.20 Orange = 0.0001
Yellow = 4 Yellow = 4 Brown = 1 Yellow = 0.00001
Green = 5 Green = 5 Red = 2
Blue = 6 Blue = 6 Orange = 3
Violet = 7 Violet = 7 Yellow = 4
Gray = 8 Gray = 8 Green = 5
White = 9 White = 9 Blue = 6
Violet = 7
Gray = 8
White = 9
FIGURE 2.40
Resistor color bands.
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