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Function of a variable resistor

Time：2024-05-26

　　A variable resistor is a resistor whose resistance value can be adjusted. It is used in applications where it’s necessary to regulate circuit current or change the circuit’s resistance. By altering its own resistance, a variable resistor can modify the characteristics of a signal generator, dim lights, start motors, or control their rotational speed. Primarily, it does this by adjusting its resistance to control the current flowing through a series circuit, thereby helping to protect certain electrical components.

　　Adjustable resistors are typically used in circuits that require frequent adjustments, serving functions such as voltage regulation, current adjustment, or signal control. Their main parameters are essentially the same as those of fixed resistors. Depending on the specific application, the resistive material of adjustable resistors can be metal wire, metal foil, carbon film, or conductive liquid. For circuits carrying currents of typical magnitude, metal-type adjustable resistors are commonly employed; when the current is very small, carbon-film adjustable resistors are preferred; and when the current is relatively large, electrolytic-type adjustable resistors are more suitable. In these adjustable resistors, the electrodes are all immersed in a conductive liquid.

　　A potentiometer is a special type of adjustable resistor that balances an unknown voltage or potential against a known reference, thereby allowing the magnitude of the unknown voltage or potential difference to be measured. A more commonly used potentiometer is simply a resistor with two fixed terminals, while the third terminal is connected to a movable brush. Another common application of potentiometers is as tone controls in audio equipment.

　　A variable resistor can function as a resistor in electronic circuits. The key difference between a variable resistor and a conventional resistor is that its resistance value can be continuously adjusted within a certain range. In applications where the resistance value needs to vary but not frequently, a variable resistor is an ideal choice. Due to their structural and operational characteristics, variable resistors have a significantly higher failure rate than ordinary resistors. Variable resistors are typically used in low-signal circuits; in a few specialized applications, such as vacuum-tube amplifiers, signal-adjustable variable resistors are also employed.

Keywords： Function of a variable resistor