Understanding resistor colour codes
Most resistors utilized in electronic circuits are too tiny to have resistance values printed on their package. Therefore, the resistance value is usually represented by color bands. Even for bigger resistors, it is often more convenient to use colour bands because printed numbers would be too hard to determine if the resistor is soiled or not oriented correctly. But there are problems with color bands also, as overheating or dirt accumulation, may make it impossible to distinguish brown from red from orange.
The utilisation of colour bands allows for straightforward and quick understanding of resistance values on a printed circuit board. There are several adaptations of the basic color coding method, where there could be 3, 4, 5, and even 6 color bands on a resistor. They are arranged in such a way that the bands are nearer to one end of the resistor, and they are read in order beginning from that end.
The first and 2nd bands represent the two significant digits which specify the numeric value of the resistor, while the color of the third band usually cites the power-of-ten multiplier. As an example, a resistor which has brown, red, and orange bands would have a value of 12K Ohms.
Because of imperfections, resistors are never the precise value the color codes indicate. As such, a fourth band is commonly used to identify 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's no fourth band present, the tolerance is understood to be 20%. The red, gold, and silver bands represent 2%, 5%, and 10% tolerances respectively.
Metal oxide resistors are rather more commonly used today because of their lower temperature coefficient and better tolerances, which are available down to 1%, with 2% or 5% being standard.
The utilisation of colour bands allows for straightforward and quick understanding of resistance values on a printed circuit board. There are several adaptations of the basic color coding method, where there could be 3, 4, 5, and even 6 color bands on a resistor. They are arranged in such a way that the bands are nearer to one end of the resistor, and they are read in order beginning from that end.
The first and 2nd bands represent the two significant digits which specify the numeric value of the resistor, while the color of the third band usually cites the power-of-ten multiplier. As an example, a resistor which has brown, red, and orange bands would have a value of 12K Ohms.
Because of imperfections, resistors are never the precise value the color codes indicate. As such, a fourth band is commonly used to identify 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's no fourth band present, the tolerance is understood to be 20%. The red, gold, and silver bands represent 2%, 5%, and 10% tolerances respectively.
Metal oxide resistors are rather more commonly 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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