Most resistors utilized in electronic circuits are too tiny to have resistance values imprinted on their package. Therefore, the resistance value is sometimes represented by colour bands. Even for bigger resistors, it is often more convenient to use colour bands because printed numbers would be too difficult to determine if the resistor is mucky or not orientated properly. However, there are problems with colour bands as well, as overheating or muck accumulation, may make it impossible to distinguish brown from red from orange.
The use of color bands allows for simple and fast understanding of resistance values on a circuit board. There are many variations of the basic colour coding scheme, where there could be 3, 4, 5, and even 6 colour bands on a resistor. They are arranged in such a way the bands are closer to one end of the resistor, and they're read in order starting from that end.
The 1st and 2nd bands represent the 2 significant digits which specify the numerical value of the resistor, while the colour of the third band normally specifies the power-of-ten multiplier. For instance, a resistor that has brown, red, and orange bands would have a value of .
Because of defects, resistors are never the exact value the colour codes indicate. As such, a 4th band is frequently used to specify the tolerance, which is a % measure of accuracy. Standard tolerance levels are 5%, 10%, and 20% for carbon-composition and carbon film resistors. If there is no 4th band present, the tolerance is believed to be 20%. The red, gold, and silver bands represent 2%, 5%, and 10% tolerances respectively.
Metal oxide resistors are far more commonly used these days because of their lower temperature coefficient and better tolerances, which are available down to 1%, with 2% or 5% being standard.
The use of color bands allows for simple and fast understanding of resistance values on a circuit board. There are many variations of the basic colour coding scheme, where there could be 3, 4, 5, and even 6 colour bands on a resistor. They are arranged in such a way the bands are closer to one end of the resistor, and they're read in order starting from that end.
The 1st and 2nd bands represent the 2 significant digits which specify the numerical value of the resistor, while the colour of the third band normally specifies the power-of-ten multiplier. For instance, a resistor that has brown, red, and orange bands would have a value of .
Because of defects, resistors are never the exact value the colour codes indicate. As such, a 4th band is frequently used to specify the tolerance, which is a % measure of accuracy. Standard tolerance levels are 5%, 10%, and 20% for carbon-composition and carbon film resistors. If there is no 4th band present, the tolerance is believed to be 20%. The red, gold, and silver bands represent 2%, 5%, and 10% tolerances respectively.
Metal oxide resistors are far more commonly used these days 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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