Most resistors employed in electronic circuits are too tiny to have resistance values written on their package. Therefore, the resistance value is usually represented by colour bands. Even for larger resistors, it is usually more practical to use colour bands because printed numbers would be too difficult to determine if the resistor is mucky or not oriented correctly. Nonetheless there are issues with colour bands also, as overheating or dirt accumulation, may make it impossible to distinguish brown from red from orange.
The utilising of color bands allows for simple and fast understanding of resistance values on a circuit board. There are a few variances of the basic color coding method, where there may be 3, 4, 5, and even 6 color bands on a resistor. They are arranged in such a way the bands are closer to one end of the resistor, and they are read in order starting from that end.
The 1st and 2nd bands represent the two significant digits which designate the numeric value of the resistor, while the color of the 3rd band often specifies the power-of-ten multiplier. For example, a resistor that has brown, red, and orange bands would have a value of .
Due to imperfections, resistors are never the precise value the colour codes indicate. Therefore, a fourth band is often used to specify the tolerance, which is a percentage measure of accuracy. Standard tolerance levels are 5%, 10%, and 20% for carbon-composition and carbon film resistors. If there is no fourth band present, the tolerance is assumed to be 20%. The red, gold, and silver bands represent 2%, 5%, and 10% tolerances respectively.
Metal oxide resistors are more widely used today because of their lower temperature coefficient and better tolerances, which are available down to 1%, with 2% or 5% being standard.
The utilising of color bands allows for simple and fast understanding of resistance values on a circuit board. There are a few variances of the basic color coding method, where there may be 3, 4, 5, and even 6 color bands on a resistor. They are arranged in such a way the bands are closer to one end of the resistor, and they are read in order starting from that end.
The 1st and 2nd bands represent the two significant digits which designate the numeric value of the resistor, while the color of the 3rd band often specifies the power-of-ten multiplier. For example, a resistor that has brown, red, and orange bands would have a value of .
Due to imperfections, resistors are never the precise value the colour codes indicate. Therefore, a fourth band is often used to specify the tolerance, which is a percentage measure of accuracy. Standard tolerance levels are 5%, 10%, and 20% for carbon-composition and carbon film resistors. If there is no fourth band present, the tolerance is assumed to be 20%. The red, gold, and silver bands represent 2%, 5%, and 10% tolerances respectively.
Metal oxide resistors are more widely used today because of their lower temperature coefficient and better tolerances, which are available down to 1%, with 2% or 5% being standard.
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