Potentiometer

What is a Potentiometer?

Un potentiometer It is a variable resistor used to adjust and control the electrical resistance in a circuit. This electronic device is used to vary the voltage or current in an electrical circuit in a gradual and controlled manner, allowing the intensity of an electrical signal or the level of a parameter in a system to be adjusted.

The potentiometers limit the passage of the electric current (Intensity) causing a voltage drop in them as in a resistance, but in this case we can modify the value of the current and the voltage in the potentiometer just by changing the value of its endurance.

Types of Potentiometers

1. Adjustment potentiometer: They are small, adjustable potentiometers designed for calibration and precise adjustments in electronic circuits. They are usually single-turn and are typically used in applications where fine adjustment is required.
2. Rotary potentiometer: This is the most common type of potentiometer as they can be single-turn, which allows an adjustment range of 270 to 300 degrees, or multiturn, which offer a greater adjustment range across multiple turns. Rotary potentiometers are used in a wide variety of applications, from volume control to gain adjustments.
3. linear potentiometer: Linear potentiometers have a linear relationship between dial position and resistance. This means that the change in resistance is uniform as the potentiometer is adjusted. They are used in applications where the relationship between position and resistance must be directly proportional, such as in linear position controls.
4. Logarithmic (or antilogarithmic) potentiometer: These potentiometers have a logarithmic relationship between dial position and resistance. They are used in audio applications, such as tone and volume controls, as they mimic the non-linear response of the human ear to volume changes.
5. Slide potentiometer: Instead of a rotary dial, sliding potentiometers have a slider that moves along a resistive track. They are commonly used in audio mixing systems and lighting applications, where linear control is important.
6. digital potentiometer: These potentiometers use digital electronics to adjust resistance and provide a digital output instead of an analog signal. They are ideal for digital control applications and can be adjusted using digital signals.
7. Endless rotary potentiometer: Also known as rotary encoders, they have no physical end and can rotate continuously in both directions. They are used in devices that require endless rotary control, such as touch screens and navigation systems.
8. Photoelectric potentiometer: They use a light signal to vary the resistance. They are ideal in situations where contactless control is essential or where environmental conditions can affect traditional potentiometers.

Circuits with Potentiometer

Let's look at the more traditional circuit.

We have a circuit to turn on a led with a 9V battery.

The LED works at a voltage of 2V, so we are going to put a fixed resistance (so that the total resistance of the circuit is never 0, in the case of setting the potentiometer to 0) and a potentiometer to cause a drop in 7V voltage between the fixed R and the Potentiometer, in such a way that the Led only has the precise 2V maximum.

If we set the potentiometer to 0 resistance, the voltage of the LED will be the maximum it can have (2V).

If we now increase the resistance of the potentiometer, the LED will be at less voltage and will shine less.

The more resistance of the potentiometer, the less voltage on the LED and it will shine less.

We can use a potentiometer to monitor the level of light, but also to monitor the volume in headphones, radios and amplifiers, the level of heat in a radiator, the lighting level of a television, record the level of gasoline in a vehicle, etc.

If we change the Led for a speaker we will control the level of the speaker.

Another of the uses of potentiometers is that of speed regulators in motors.

If we put a potentiometer in series with a motor, increasing the resistance of the potentiometer will reduce the speed of the dc motor.

This is best done with a transistor.

The potentiometer controls the intensity that the transistor sends to the motor.

The potentiometer controls the base intensity.

To learn more about the transistor click on the underlined link.

Let's see the scheme.

In the next video we show you how the usual potentiometer circuit is and measurements with the different values ​​it can take.

Source of information used: https://www.areatecnologia.com/electronica/potenciometro.html