Potentiometer vs Rheostat
Potentiometer and rheostat are two components that are used in electronics. Potentiometer is not only used as an electronic component but also a measuring instrument. A rheostat is basically used to vary the resistance of a circuit. These two components are used in both laboratory and industrial purposes. In this article, we are going to discuss what potentiometer and rheostat are, their definitions, applications of potentiometers and rheostats, the similarities between them, and finally the difference between potentiometer and rheostat.
Potentiometer
Potentiometer is described as a component in electronics and a measuring instrument too. The potentiometer is used for measuring the potential (voltage) of a circuit. These were widely used in laboratories before the introduction the moving coil and digital voltmeters.
There are four types of potentiometers known as constant current potentiometers, constant resistance potentiometers, microvolt potentiometers, and thermocouple potentiometers. Potentiometers are used as voltage dividing components in electronics. It is a three terminal resister with a sliding contact that forms an adjustable voltage divider. A potentiometer consists of a resistive element, a sliding contact (wiper) moving along the resistive element, electrical terminals at each end of the element and a housing containing the element and the wiper. The resistive element of a potentiometer is often made up of graphite.
There are two types of potentiometers used in electronics known as linear taper potentiometers and logarithmic potentiometers. Potentiometers are used in audio controls for controlling audio equipments, changing loudness, frequency attenuation and other characteristics of audio signals. In televisions, they were formerly used to control picture brightness, contrast and color response.
Rheostat
Rheostats are mostly used to vary the resistance in a circuit. It is a two terminal variable resistor. There are two methods for building up a rheostat. One is winding a resistance wire around a semicircular insulator with the wiper sliding from one turn of the wire to the next. The other way is winding a resistance wire on a heat-resisting cylinder, with the slider made from a number of metal fingers that grip lightly onto a small portion of the turns of resistance wire.
These rheostats are applied in DC motor drives, electric welding controls, or in the controls for generators. There is another type of rheostat which is known as liquid or salt water rheostat. They are widely used by generator assemblers because they have a unity power factor.
Potentiometer vs Rheostat
- Potentiometer is a component having three terminals, but rheostat has only two terminals.
- There are two types of potentiometers based on their duty as a measuring instrument or a component in electronics, but rheostats basically used to vary the resistance of a circuit.
- Potentiometers are used for low power applications (less than about one watt), but rheostats are used for high power applications (more than about one watt).
- When a potentiometer is built up, resistive elements are used, but they are not used for building up rheostats.