What are the characteristics of SMD adjustable resistors?

Allowable deviation, the nominal capacitance is the capacitance marked on the capacitor. The deviation between the actual capacitance of the capacitor and the nominal capacitance is called the error, and the accuracy is called within the allowable deviation range. The correspondence between the accuracy level and the allowable error %-30%) is commonly used for general capacitors, and the grade is used for electrolytic capacitors, which is selected according to the application.

Insulation resistance, the ratio of DC voltage added to the capacitor and the leakage current is generated, which is called insulation resistance. When the capacitance is small, it mainly depends on the surface state of the capacitor, and when so, it mainly depends on the properties of the dielectric, and the greater the insulation resistance, the better. Time constant of capacitance:

To evaluate the absolute...

1. Overview of the important characteristics of chip tunable resistors.

1. Different resistance characteristics at different frequencies: in the AC circuit, the resistance value of the same chip adjustable resistor to the signal of the painless frequency is the same, and the resistance value will not change due to the different frequencies of the AC point, which is an important feature of the chip adjustable resistance, after understanding this characteristic, when analyzing the working principle of the resistor in the AC circuit, you can not consider the influence of the alternating current frequency on the circuit work; The chip adjustable resistor does not change the resistance not only in the sine wave alternating current circuit, but also in the pulse signal, tripod wave signal processing, and amplification circuits.

2. The resistance characteristics of DC and AC circuits are the same: in DC or AC circuits, the chip adjustable resistor plays the same role in hindering the current, in other words, the chip adjustable resistor hinders the AC and DC current is "the same". Therefore, the chip adjustable resistor is good for DC and has the same effect as AC, which greatly facilitates the analysis of resistance circuits, that is, DC or AC can not be considered when analyzing pure resistance circuits.

3. Basic characteristics: it consumes electrical energy, and when the current flowing through it is too large, it will heat up until it burns out.

Second, the key points of circuit analysis are broadcast.

It is simpler to analyze the working principle of the chip tunable resistor circuit than to analyze the working principle of the chip tunable resistor, because the characteristics of the chip tunable resistor are relatively simple. If it is alternating current, there is no need to consider factors such as frequency, but only the influence of the resistance value of the resistance on the current size is analyzed, because the resistance characteristics of the chip adjustable resistor are the same as those presented by these electrical signals.

For details, please refer to it.

SMD resistors are resistors made by mixing metal powder and glass glaze powder and printing on a substrate using screen printing. Resistant to humidity and high temperatures, low temperature coefficient. It can greatly save the cost of circuit space and make the design more refined.

SMD resistor is sputtered on a layer of alloy resistance film on a ceramic substrate in a vacuum, and is made of glass material protective layer and three layers of electroplating, which has high reliability, uniform appearance size, accuracy and small temperature coefficient and resistance tolerance.

Characteristics of chip resistors: small size, light weight; Adapt to reflow soldering and wave soldering; Stable electrical performance and high reliability; Low assembly cost and matching with automatic mounting equipment; High mechanical strength and high frequency characteristics.

SMD resistor: one of the metal glass glaze resistors.

Guanfa chip resistor, also known as chip fixed resistor, is a resistor made by mixing metal powder and glass uranium powder and printing it on a substrate by screen printing. There are many subdivisions of chip resistors, which are commonly divided into conventional thin film chip resistors and high-precision and high-stability chip resistors.

During the repair of an electronic device, I once found that the resistance of the chip resistor became larger, which caused the electronic device to leak and not work properly. The increase in the resistance of the demount chip can be caused by a variety of reasons, such as: 1

Due to the long-term use of electronic equipment, the temperature of the chip resistor increases, resulting in a larger resistance value; 2.Due to the improper maintenance of electronic equipment, the contact of the chip resistance is poor, resulting in the resistance value becoming larger; 3.Due to improper assembly of the electronic equipment, the chip resistor is installed incorrectly, resulting in a large resistance value.

Expansion: In addition, the increase in the resistance of the chip resistor may also be caused by the quality of the slag wheel in the electronic equipment, such as the poor material quality of the chip resistor, or the size of the chip resistor does not meet the requirements.

The method of rotating the adjustable resistance of the SMD: you can use a screwdriver to operate, generally choose to adjust to the left to adjust the resistance value, and to the right to rotate and adjust the resistance value. The chip adjustable resistor is to adjust the volume by adjusting the adjustable resistor to change the gain of the pre-voltage amplification and change the amplitude of the audio signal.

Precautions for SMD adjustable resistorsThe rated power of the SMD adjustable resistor should not be overloaded, otherwise it is easy to cause the resistance deviation of the resistor to be too large in use, and it is also possible that the resistor may burn out due to excessive power.

When the chip resistor is running at too high a working temperature, it is necessary to pay attention to whether the heat dissipation of the resistor is normal, and consider installing a radiator in appropriate cases, otherwise the connection between the resistor and the line will not be able to bear the load, resulting in the burning of the resistor. When welding the chip resistor, it is necessary to avoid some shaking or vibration, so as not to prevent the resistor from soldering or not being firm.

01a：100ω

01b：1000ω

01c：10000ω

01d：100000ω

01 represents 100, and a, b, c, and d are to the power of 0, 1, 2, and 3 of 10 respectively. So 01b=100 10=100

This method is called the e96 numeric ** mixed letter nominal method.

The numeric ** and alphabetic mixed nominal method also uses three digits to indicate the resistance value, that is, "two digits plus one letter", where the two digits represent the E96 series resistors Schedule 2. Its third digit is the magnification indicated by the letter **. For example:

51d" means "332 10 3;332kω”；249y" means "249 10 -2;"。

The chip resistor package is 01005, 0201, 0402 because the resistor body is too small, so the body is not marked with a font code; Therefore, the chip resistance of these packages can only be distinguished by a multimeter.

1. The 5% tolerance resistance code of the chip resistance is three digits, the first two digits are the significant numbers of the resistance value, and the third digit indicates that there are several 0s.

2. SMD resistor package 0805, 1206, 1210, 2010, 2512 1% tolerance product code has four digits, the first three digits are the significant digits of the resistance, and the fourth digit indicates that there are several 0s.

3. SMD resistor package 0603 1% tolerance E-96 series standard resistance, because the resistance body is too small, the three-digit resistance value ** (number) and the following index ** (letter) are used to indicate the standard resistance value.

Index code (0603 1% indication).

**：a--b--c--d--e--f--g--h--x--y--z

Index: 100--101--102--103--104--105--106---107--10-1--10-2--10-3