IDIOMA (LANGUAGE) : ESPAÑOL
WHAT IS A POTENTIOMETER?
It is an electrical resistor with a variable resistance value and usually manually adjustable. The potentiometers have three terminals and are usually used in circuits of low current, for circuits of greater current the rheostats are used. In many electrical devices the potentiometers are what set the output level. For example, in loudspeaker, the potentiometer adjusts the volume, on a television or a computer monitor it can be used to control the brightness.
The value of a potentiometer is expressed in ohms as the resistors, and that value always corresponds to the maximum resistance it can have. The minimum vale is logically zero. For example, a 5kΩ potentiometer can have a variable resistor with values between 0Ω and 5000Ω.
The simplest potentiometer is a mechanically variable resistor. The first potentiometer simpler are the rheostats.
TYPES OF CONSTRUCTION OF A POTENTIOMETER
Made with a cermet or carbon track on a hard support such as bakelised paper (cardboard prespan), fiberglass, bakelite, etc. The track has contacts at its ends and a cursor connected to a skate that slides down the resistive track.
It consists of a toroidal winding of a resistive wire (could be constantan) with a cursor that moves a skate on itself.
TYPES OF POTENTIOMETERS
The potentiometers can be classified in two ways:
They are suitable for controlling the voltage in electronic devices. The user operates on them to vary the normal operating parameters of the electronic devices. For example, the volume of an audio device, vary the frequency of a radio.
They are controlled by turning their axis. They are the most common because they are long lasting and use little space.
The path of the cursor on the resistive track is straight, they are used in graphic equalizers. They are more fragile than rotary, they occupy more space and are usually more sensitive to dust.
There are several potentiometers on a single axis, so they use little space. They use in instrumentation circuits, radios, etc.
ACCORDING TO THE LAW OF VARIATION OF RESISTANCE
The resistance is directly proportional to the angle of rotation.
These are normally used for audio due to their asymmetric behavior due to the variation of their axis. At the beginning a very tenuous resistance increase is reflected, until reaching a point where the increase will be much greater, it is considered that the resistance depends logarithmically of the angle of rotation. They are often used for example for volume control of a radio.
The resistance is proportional to the sine of the angle of rotation. Two integral sine-wave potentiometers rotated 90° provide the sine and cosine of the angle of rotation. They may have limit stops or not.