Tuesday 23 July 2013

Resistor color-coding





 A diagram of a resistor, with four color bands A, B, C, D from left to right A diagram of a 2.7 MΩ color-coded resistor.
A 2260 ohm, 1% precision resistor with 5 color bands (E96 series), from top 2-2-6-1-1; the last two brown bands indicate the multiplier (x10), and the 1% tolerance. The larger gap before the tolerance band is somewhat difficult to distinguish.

To distinguish left from right there is a gap between the C and D bands.

    band A is first significant figure of component value (left side)
    band B is the second significant figure (Some precision resistors have a third significant figure, and thus five bands.)
    band C is the decimal multiplier
    band D if present, indicates tolerance of value in percent (no band means 20%)

For example, a resistor with bands of yellow, violet, red, and gold will have first digit 4 (yellow in table below), second digit 7 (violet), followed by 2 (red) zeros: 4,700 ohms. Gold signifies that the tolerance is ±5%, so the real resistance could lie anywhere between 4,465 and 4,935 ohms.

Resistors manufactured for military use may also include a fifth band which indicates component failure rate (reliability); refer to MIL-HDBK-199 for further details.

Tight tolerance resistors may have three bands for significant figures rather than two, or an additional band indicating temperature coefficient, in units of ppm/K.

All coded components will have at least two value bands and a multiplier; other bands are optional.

The standard color code per EN 60062:2005 is as follows:







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