Understanding is key for you to be in a position to read resistor color codes, you also need to have an understanding of the math behind each band that is used in the indication of resistance, tolerance, value, and even temperature coefficient.
Identify Resistors Color Code
Resistors come in different physical sizes, values, and shapes. Leaded resistors that have a power rating of up to one watt have a pattern of colored bands that are used to indicate tolerance, resistance value, and temperature coefficient.
The body of the resistor can have anywhere from three to six colored bands, however, four bands are very common. The value of the resistance is represented by the first few bands. There’s also the multiplier band which signifies movements in the decimal either to the right or left. Lastly, you have the bands that represent tolerance and the temperature coefficient.
Three or Four Band Resistors
For the three or four band resistors, the first two bands are used to denote the first two digits of the resistance value in ohms. The third band represents the multiplier which basically shifts the decimal place around so as to change the value from mega ohms to milliohms including the values in between. Tolerance is signified by the fourth color band. However, you need to keep in mind that if the fourth band is absent in a three-band resistor, the default tolerance is ±20%.
Five or Six Band Resistors
This range works for resistors that have high precision, they come with an extra color band which indicates the third significant digit. In the event that you find a resistor with five or six colors remember that the third one is the additional digit along with bands one and two. The other digits shift to the right such that the fourth color band now becomes the multiplier while the fifth band shows the tolerance. For the six-band resistor it’s the same concept as the five-band but with an additional ring which indicates the reliability, or temperature coefficient (ppm/K) specification.
Zero-ohm resistors are recognized by their single black band, they are basically wire links used to connect traces on a printed circuit board. They are packaged like a resistor so the same automated equipment used to place resistors can also be used to place these on the circuit board.
Memorizing the order of colors on the chart?
You can set the color chart to your memory by thinking of black as the absence of color, so it is “0”, while white is the combination of all colors, so it is the highest value, “9”. In the middle of the color chart you will find the standard rainbow colors in order for numbers 2 through 7, so your childhood ROY-G-BIV acronym comes into play, minus the color indigo. Just remember that brown fits between black and red as number “1” and grey fits between violet and white as “8” and you’ve got it! This strategy will help you remember the color chart.
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