We often use color ring resistors in the circuit. It is also a basic function of the electrician to quickly read the resistance value. The following describes the color ring reading method:
Each color represents a different number, as follows:
Brown 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Purple 7 Gray 8 White 9 Black 0, gold and silver indicate error, gold is 5% error. Silver is 10% error.
By the way:
1, 2, 3, 4, 5, 6, 7; brown, red, orange, yellow, green, blue, purple
8 ash 9 white 0 is black; there are gold and silver often in mind to keep in mind four sentences; accident away from never return
In practice, it has been found that some color ring resistors are not clearly arranged in order, and are often easy to read. In recognition, the following techniques can be used to judge:
Tip 1: First find the color circle of the mark error, and then arrange the color ring order. The most commonly used colors for resistance errors are: gold, silver, brown, especially gold rings and silver rings, which are rarely used as the first ring of the resistance color ring, so as long as there are gold rings and silver rings in the resistance, It can be basically assumed that this is the last ring of the color ring resistance.
Tip 2: Whether the brown ring is the discriminant of the error sign. The brown ring is often used as an error loop, and often as an effective digital ring, and often appears in both the first ring and the last ring, making it difficult to identify who is the first ring. In practice, it can be discriminated according to the interval between the color rings: for example, for the resistance of a five-color ring, the interval between the fifth ring and the fourth ring is smaller than the interval between the first ring and the second ring. To be wider, it is possible to determine the order in which the color rings are arranged.
Tip 3: In the case where the color circle interval cannot be determined by the color circle spacing alone, the production sequence value of the resistor can also be used for discrimination. For example, the color ring read order of a resistor is: brown, black, black, yellow, brown. Its value is: 100×104Ω=1MΩ, the error is 1%, which belongs to the normal resistance series value. If it is reverse order read: brown, yellow , black, black, brown, the value is 140 × 100 Ω = 140 Ω, the error is 1%. Obviously, the resistance values ​​read out in the latter order are not found in the production series of resistors, so the latter color ring sequence is incorrect.
The resistance is generally divided into: carbon film resistance, metal film resistance, cement resistance, wire resistance and the like. General household appliances use more carbon film resistors because of their lower cost. Metal film resistors have higher precision and are used on more demanding equipment. Both the cement resistor and the wire friction resistor can withstand relatively high power, and the precision of the wire friction resistor is also relatively high, and is commonly used on highly demanding measuring instruments.
Low-power carbon film and metal film resistors generally use color rings to indicate the resistance value, which is also an important step in learning resistance. The unit of resistance is ohms. The details are explained below.
The color ring resistance is divided into four color rings and five color rings, first speaking four color rings. As the name implies, four colored rings are used to represent the resistance. Each color represents a different number, as follows:
Brown 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Purple 7 Gray 8 White 9 Black 0 Gold and silver indicate the error color rings represent the following meaning:
The first color circle: the first digit of the resistance value;
The second color circle: the second digit of the resistance value;
The third color circle: a power of 10;
The fourth color circle: the error is expressed.
For example: resistance color ring: brown green red gold, first digit: 1; second digit: 5; third digit: power of 10 is 2 (ie 100); error is 5%; ie resistance value: 15×100 =1500 ohms = 1.5 kohms = 1.5K
There is also a more accurate "five-color ring" resistor, which uses five color rings to indicate the resistance of the resistor, as follows:
The first color circle: the first digit of the resistance value;
The second color circle: the second digit of the resistance value;
The third color circle: the third digit of the resistance value;
The fourth color circle: a power of 10 of the resistance multiplier;
Fifth color circle: error (commonly brown, error is 1%)
Some five-color ring resistors have color rings on the two metal caps, and the color ring away from the relatively concentrated four-color ring indicates the error, which is the fifth color ring, and the other metal cap corresponding to the first color is the first color. Ring, read from it, the second and third color rings are the next highest and second highest, and the fourth ring represents the number of powers of 10, for example, the resistance color ring resistance sequence is: red ( 2) - Black (0) - Black (0) - Black - Brown, then it means that the resistance is: 200 × 100 Ω. Another example is brown-black-black-red-brown, indicating that the resistance is 100×102 Ω=10000 Ω=10 KΩ. It can be seen that the four-color ring resistance error is 5-10%, the five-color ring is often 1%, and the precision is improved.
For example: there is resistance: yellow purple red orange brown, the first three digits are: 472, the fourth digit represents the third power of 10, that is, 1000, the resistance value is: 472 × 1000 ohms = 472 kilo ohms (ie 472K)