Variable Resistors and Their Common Types
A resistor is an electronic part type that is found in many circuit assemblies, tasked with implementing electrical resistance. Coming in a variety of forms, resistors can be used for adjusting signal levels, dividing voltages, terminating transmission lines, biasing active elements, and much more. There are also two major groups of resistors, those being fixed resistor and variable resistor types. While fixed resistor components exhibit a set resistance level that remains constant over time, variable resistors are able to have their resistances changed so that they can adjust circuit elements or act as a sensing device. In this blog, we will discuss the common types of resistors that feature adjustable resistance, allowing you to better understand how such components are used within the realm of electronics.
Potentiometers are one of the primary types of variable resistors that exist on the market, and such components feature three terminals and an adjustable tapping point that is managed by a shaft, knob, or linear slider. Typically, a potentiometer will act as a resistive divider, allowing for voltage signals to be produced based on the positioning of the device. With their capabilities, a potentiometer will enable the control of volume, the measurement of distances or angles, the tuning of circuits, and more. For tuning or calibrating various circuits, a trimmer potentiometer or trimpot in particular may be relied on.
Rheostats are another major form of variable resistor, and such components differ from potentiometers in the fact that they utilize two terminals instead of three. One of these terminals allows for a connection to be established at the end of the resistance element, while the other terminal attaches to the variable resistor’s wiper. While such devices originally served to control light bulbs and similar products, their inefficiency in power control applications has caused them to change in use. Nowadays, rheostats are primarily found within circuitry where tuning or calibration is required. When serving such applications, rheostats come in the form of preset variable resistors that are wired to be a rheostat.
While potentiometers and rheostats are the two most common types of variable resistance components, there are also other types such as the digital variable resistor. With such devices, changes in resistance are made through electronic signals, rather than relying on mechanical movements. When adjusting resistance levels, a digital variable resistor will often conduct changes in discrete steps or will emit basic up and down signals.
Alongside such examples, there are multiple special devices that can feature the ability to adjust resistance changes with various quantities. A strain gauge is an example of such special devices, coming in the form of a resistor that exhibits resistance value adjustments when strain is applied to it. Bonded to an object with an adhesive, any mechanical strain induced on the object will cause the resistor to change in resistance. With such an assembly, the strain of an object can be measured for various applications.
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