Page 32 - Testing Electronic Components

Resistor Colour Code Calculation

Fixed resistors are marked in several ways. These are:
i. Color coding
ii. Straight numerical value
iii. Certain numerical codes that can be easily translated.

Because carbon resistors are small physically, they are color coded to
mark their R value in ohms. In memorizing the colors, note that the
darkest colors, black and brown, are for the lowest numbers, zero and
one, through lighter colors to white for nine. Technicians must know this
code.
Table 1 and 2 shows the colour code and their meanings.

Colour Digit Multiplier Tolerance
Black 0 1 10 - -
Brown
1
Red 2 100 -
First Band Orange 3 1000 -
(First Digit) Yellow 4 10000 -

Second Band Green 5 100000 -
(Second digit) Blue 6 1000000 -
Violet 7 10000000 -
Third Band Grey 8 - -
(Multiplier)
White 9 - -
Fourth Band Gold - 0.1 +5%
(Tolerance) Silver - 0.01 +10%
No colour - - +20%

TABLE 1- Showing four colours band of resistor and their meanings.

Tolerance Code
First Band Black -
(First Digit) Brown +1%
Red +2%
Second Band
(Second digit) Orange -
Yellow -
Third Band Green +0.5%
(Third digit) Blue +0.25%

Fourth Band Violet +0.1%
(Multiplier) Grey +0.05%
White -
Fifth Band
(Tolerance) Gold +5%
Silver +10%
TABLE 2- Showing five colours band of resistor and their meanings.

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