What is a carbon film resistor What are the resistance marking methods of carbon film resistors?

It is made by using high-temperature vacuum coating technology to tightly attach carbon to the surface of the porcelain rod to form a carbon film, and then cut it with appropriate joints, and coat its surface with epoxy resin to seal and protect. Its surface is often coated with green protective paint. The thickness of the carbon film determines the magnitude of the resistance, and the resistor is usually controlled by controlling the thickness and notch of the film.

Resistor knowledge.

Resistors Resistors are used in electronic circuits to control voltage and current. Resistors are often referred to as resistors. There are many types of resistors, which are divided into three types: fixed resistance, variable resistance and potentiometer.

Figure 11Structure and characteristics of commonly used resistors. Commonly used resistors include carbon film resistors, carbon resistors, metal film resistors, wirewound resistors and potentiometers. Table 1 shows the structure and characteristics of several commonly used resistors.

Table 1 The structure and characteristics of several commonly used resistors.

Types of resistors. Resistive structure and characteristics.

Carbon film resistors. Gaseous hydrocarbons decompose at high temperatures and in vacuum, and carbon is deposited on porcelain rods or tubes, forming a crystalline carbon film. Different resistance values can be obtained by changing the thickness of the carbon film and changing the length of the carbon film by notching. Carbon film resistors have low cost and average performance.

Metal film resistors.

The alloy is heated in a vacuum, and the alloy evaporates, forming a conductive metal film on the surface of the porcelain rod. Notching and changing the thickness of the metal film can control the resistance. Compared with carbon film resistors, this kind of resistor is smaller, lower noise, and better stability, but the cost is higher.

Carbonaceous resistors. It is made by pressing a mixture of carbon black, resin, clay and other materials after heat treatment. A color ring is used on a resistor to indicate its resistance value. This type of resistor has a low cost and a wide range of resistance values, but has poor performance and is very small to adopt.

Wirewound resistance. It is made of constantan or nickel-chromium alloy resistance wire wound on a ceramic skeleton. There are two types of resistance: fixed and variable. It is characterized by stable work, good heat resistance, small error range, suitable for high-power occasions, and the rated power is generally more than 1 watt.

Carbon film potentiometer.

Its resistor body is made of a horseshoe-shaped paper plyboard coated with a layer of carbon film. There are three types of relationship between the change of resistance value and the position of the intermediate contact: linear, logarithmic and exponential. There are several types of carbon film potentiometers: large, small, and miniature, and some of them form potentiometers with switching together with switches.

There is also a direct-slide carbon film potentiometer, which relies on a slide rod to slide on the carbon film to change the resistance value. This potentiometer is easy to adjust.

Wirewound potentiometers.

It is made by winding a resistance wire on a ring-shaped skeleton. It is characterized by a small resistance range and a large power.

Carbon film resistors are electronic components, different types have different uses, you can find instructions on the Internet according to the model!

2. Text symbolic method: use Azhizhou Labor numerals.

and the text symbol are regularly combined to represent the nominal resistance, and its allowable deviation is also represented by the text symbol. The number before the symbol indicates the integer resistance, and the following numbers represent the first decimal resistance and then the second decimal resistance.

3. Digital method: in the resistor.

A notation method that uses three digits to represent the nominal value. Numbers from left to right, first.

The first and second digits are the valid values, and the third digit is the exponent, that is, the number of zeros, and the unit is European. Deviations are usually represented by literal symbols.

I would like to take a number of carbon film resistors.

4. Color code method: mark the nominal resistance value and allowable deviation on the surface of the resistor with different colored bands or dots. Most of the foreign resistors use the color code method.

Black-0, Brown-1, Red Xiangshou-2, Orange-3, Yellow-4, Green-5, Blue-6, Purple-7, Gray-8, White-9, Gold-5%, Silver-10%, Colorless - 20%.

When the resistor is four rings, the last ring must be gold or silver, with the first two digits being significant figures and the third digit being the power.

number, and the fourth digit is the deviation.

When the resistance is five rings, the distance between the last ring and the first four rings is larger. The first three digits are significant figures, the fourth digit is the number of the multipliers, and the fifth digit is the deviation.

Carbon film resistors generally use the color code method.

Landlord, let me tell you: we generally use the color scale method.

Use different colored bands or dots to mark the nominal resistance and allowable deviation on the surface of the resistor. Most of the foreign resistors use the color code method.

Black-0, Brown-1, Red-2, Orange-3, Yellow-4, Green-5, Blue-6, Purple-7, Gray-8, White-9, Gold-5%, Silver-10%, Colorless - 20%.

When the resistor is four rings, the last ring must be gold or silver, the first two digits are significant figures, the third digit is the power number, and the fourth digit is the deviation.

When the resistance is five rings, the distance between the last ring and the first four rings is larger. The first three digits are significant figures, the fourth digit is the number of the multipliers, and the fifth digit is the deviation.

If the landlord has any questions, contact him again.

<> Identification of the four color ring resistors:

The first and second rings represent the resistance of two significant digits, respectively; The third ring represents the magnification; The fourth ring represents the error.

Example: Brown, Red, Red Gold, its resistance value is 12 10 2= error is 5% error indicates the resistance value, fluctuating up and down the standard value of 1200 (5% 1200) indicates that this resistance is acceptable, that is, between 1140-1260 is a good resistance.

Commonly used carbon film resistors are known as space models: Qinghuan blind 1 8w 1 4w 1 2w 1w 2w 3w 5w and other models.

Carbon film resistance nominal resistance: The nominal resistance value on the resistor is called the nominal value. Units are expressed in ohms ( ).

It includes (ohms), k (kiloohms), m (megaohms). The conversion relationship is: 1m = 1000k, 1k = 1000.

The nominal value is marked according to the standard series set by the state, and is not arbitrarily calibrated by the producer. Not all resistors are present. The resistance range of carbon film resistors is 1 10m.

Allowable Error: The maximum allowable deviation range of the actual resistance of the resistor from the nominal value is called the allowable error. Error**: f, g, j, k

Rated power: refers to the allowable power consumption on the resistor under the condition that the performance of the resistor is not damaged or basically changed under the condition that the surrounding air is not circulated at the specified ambient temperature, assuming that the surrounding air is not circulating. The rated power of the carbon film resistor is not marked on the shell of the resistor, but is distinguished by the length and diameter of the electron gun.

Carbon film resistors generally have rated power, etc.

In order to meet the needs of small volume resistors, small carbon film resistors RTX type are produced, with a power of only, and most of them are made into color-coded resistors.