Electronics components Electronics tutorial Passive components

What are Potentiometers or Variable Resistors?

Potentiometers are electrical component used to measure or adjust voltage or current, it usually consists of a rotary or sliding adjusting device, and three electrical contacts, one of which is connected to the power supply, the other is grounded, and the third can be moved on the adjusting device of the potentiometer, which can be used to regulate current or voltage in the circuit by changing the distance between the third electrical contact and the power supply.

Difference between variable resistor and potentiometer:

  • Variable Resistor (Rheostat): A two-terminal device used to adjust current or voltage in a circuit.
  • Potentiometer: A three-terminal device used to adjust voltage (as a voltage divider) or resistance.

Potentiometer can be used for volume control, light control, electronic equipment regulation, laboratory measurements, etc. This article will introduce you to the principle of the potentiometer, role and use.

Principle of Potentiometers:

Potentiometer is a commonly used electronic components, its principle is based on the change of resistance to regulate the flow of charge in the circuit, usually, the potentiometer consists of a rotating shaft and a ring-shaped part with resistive material, by rotating the potentiometer’s shaft, you can change the position of the resistive material in the circuit, so as to change the magnitude of the electric) voltage.

The potentiometer acts similarly to a tap, by rotating the tap the size and strength of the water flow can be adjusted, the potentiometer can also be rotated to adjust the flow of charge in the circuit. Potentiometers have two main ports, one of which is connected to a power source (e.g., a battery) and the other to a load (e.g., a light bulb). The middle portion of the potentiometer carries a resistive material, and when the shaft of the potentiometer is rotated, it will change the position of the resistive material in the middle portion between the load and the power supply.

When the potentiometer is rotated to a certain position, the resistive material will change the voltage between the power supply and the load; if the potentiometer’s resistance is very low, then just a very small amount of charge will flow through the load, and if the potentiometer’s resistance is very high, then most of the charge will pass through the potentiometer, not the load. By adjusting the potentiometer, the current and voltage in the load can be effectively controlled, thus enabling the control and regulation of the electrical energy of the circuit.

Linear Potentiometers:

In addition to regulating the flow of charge in a circuit by rotating the shaft of the potentiometer, there is also a variant known as a linear potentiometer, which is based on the principle of adjusting the size of the resistance according to the movement of the shaft. This type of potentiometer can be used for volume adjustment in audio equipment, whereby by mounting a linear potentiometer on the volume knob, the size of the output audio signal in an amplifier can be controlled.

Potentiometer is one of the important electronic components to achieve circuit power regulation, it is based on changes in resistance to control the flow of charge in the circuit, can be adjusted according to the need to adjust the current and voltage in the circuit, and has a wide range of applications in electronic circuits.

Applications of Potentiometers:

Adjust The Circuit Voltage:

By adjusting the potentiometer, you can change the resistance value in the circuit, thereby controlling the voltage size of the circuit, which is very common in many circuits, especially in DC power supply circuits, the resistance value of the potentiometer is usually in a small range of changes in the changes in the current through it also changes, thereby changing the voltage value of the circuit.

Control Current:

Potentiometer can be used to control the current in the circuit, such as in the amplifier to control the size of the offset current, offset current is a common problem in the amplifier, if not controlled, it will easily lead to sound quality degradation. At this point, by adjusting the resistance of the potentiometer, the size and direction of the offset current can be controlled, thus improving the sound quality.

Adjust the Amplification Factor:

Potentiometer can also be used to adjust the amplification factor in the circuit, especially in the amplifier is very common, this is because the amplifier often need to amplify the low voltage signal to a higher voltage range, so that it can be normal output. At this point, by changing the resistance of the potentiometer, you can change the amplifier’s amplification factor, making its output more in line with the requirements.

Volume Control:

Potentiometer can also be used to control the size of the sound, is one of the commonly used components in electronic products, for example, the volume control of the stereo is achieved by the potentiometer, by rotating the potentiometer, you can change the resistance value in the circuit, thus changing the output volume.

Using Potentiometer:

When using a potentiometer, the following points need to be observed.

Understand the Basic Structure and Principle of the Potentiometer

Potentiometer is mainly composed of a base, knob and three pins, when the knob is rotated, the internal carbon film resistance will change, so that the resistance value changes, the use of potentiometers need to understand the basic principles of the circuit and pay attention to the matching use.

Correctly Connect the Potentiometer

When connecting the potentiometer, be sure to pay attention to the wiring order of the pins, as well as the polarity of the voltage and current. Generally speaking, the middle pin of the potentiometer is connected to the circuit point that needs to be adjusted, and the pins at both ends are connected to the power supply and ground.

Adjust the Resistance Value

The use of potentiometers, according to the need to adjust the resistance value, generally with the knob clockwise or counterclockwise direction of rotation, gradually adjust the knob until the desired resistance value, it should be noted that the maximum resistance value of the potentiometer and the rated power to meet the requirements of the actual application.

Use in Special Circumstances

In some special applications, need to consider the special use of potentiometers, such as in high-frequency circuits, to use special high-frequency potentiometers, in the anti-static environment, to use anti-static potentiometers and so on.

In summary, the use of potentiometers not only includes the basic operation of the circuit principle and resistance adjustment, but also need to take into account the connection of the pins and the use of special applications, the use of potentiometers, we must strictly comply with the use of procedures to ensure the safety and stability of the circuit.

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