Appendix C
Resistor Colour Code
Resistors are normally coded with coloured bands to enable quick
identification of their value. The colour code specifies the value of
the resistor, in ohms, and the maximum deviation from the stated
value (the tolerance). Most resistors have a manufacturer's tolerance
with is adequate for most electronic applications
Interpreting the Colour Code
The four colour code bands are at one end of the component.
Counting from the end, the first three (or sometimes four) bands give the resistance value
and the last the tolerance. The significance of the colours is
shown in the table below:
| First 3 (or 4) bands | Tolerance band |
| Black | 0 | Brown | 1% |
| Brown | 1 | Red | 2% |
| Red | 2 | Gold | 5% |
| Orange | 3 | Silver | 10% |
| Yellow | 4 | No band | 20% |
| Green | 5 | | |
| Blue | 6 | | |
| Violet | 7 | | |
| Grey | 8 | | |
| White | 9 | | |
Reading the value (three band)
The first two bands are used to specify the first two digits of the
resistor's value. The third gives the number of noughts to be added.
Thus in this example, yellow and violet give the first two digits as 4
and 7 and the number of zeros is 3 (orange) giving a value of 47000 ohms.
Four Band Resistors
More modern resistors use four bands to specify the resistance, the
first three giving the three most significant digits and the fourth
the number of zeros. Yellow, violet, black, red decodes as 4, 7, 0,
00 ie. 47000 ohms.
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