The resistor of the plug-in resistor is made of raw materials, has a certain structure, and can limit the current passing in the power circuit. Plug-in resistor type resistors are mainly used to adjust and stabilize current and voltage in circuits. A resistor whose resistance value cannot be changed is called a fixed resistor. The variable resistance value is called potentiometer or variable resistor. The ideal resistor is linear, i.e. proportional to the instantaneous applied voltage according to the instantaneous current through the resistor. Some unique resistors, such as thermistors, varistors, precision resistors, and sensitive components, have a nonlinear voltage-current relationship.

Precision resistors are the most widely used components in electronic circuits. They usually form different series of resistors according to power and resistance value for circuit designers to choose. Replacement principle for resistors:

1. Use a resistor with a smaller resistance in series to replace a resistor with a large resistance, or use a resistor with a larger resistance in parallel to replace a resistor with a small resistance.

2. When replacing high-power resistors with low-power resistors, series or parallel methods can be used. When the resistance values of the series and parallel low-power resistors are not equal, the power shared by them should be calculated so that the total power is greater than the rated power of the original resistor.

3. The substitute resistors should follow the principle of whether it is high or low, or large or small, that is, use high-quality resistors to replace the original low-quality resistors, and high-power resistors to replace low-power resistors.

The development direction of cylindrical resistance:

1. Miniaturization and high reliability;

2. Discrete small resistors are still widely used, but will further reduce the size, improve performance, and reduce prices;

3. In consumer electronic products, carbon film resistors are still dominant, while precision resistors will be dominated by metal film resistors, and most low-power wirewound resistors will be replaced;

4. In order to adapt to the development of circuit integration and planarization, the need for chip resistors will increase significantly; general-purpose types will tend to develop thick film resistors, while precision resistor types will still tend to thin-film metal films. and metal foil resistors;

5. Develop a combined resistance network.