Characteristics of resistance change of exponential potentiometer, logarithmic potentiometer, linear potentiometer

Potentiometers can be divided into exponential potentiometers, logarithmic potentiometers, and linear potentiometers according to the linear change of resistance. The so-called resistance linearity of the potentiometer refers to the rotation angle (or stroke) of the potentiometer and when used as a voltage divider The relationship between output voltage. The resistance value of the potentiometer varies with the rotation angle of the contact point of the sliding piece. This relationship can be in any functional form in theory.

The resistance change characteristic of the potentiometer refers to the relationship of the resistance value of the potentiometer with the change of the length of the movable contact or the angle of the rotating shaft, that is, the resistance output function characteristic. There are 3 commonly used:

1) Characteristics of resistance change of exponential potentiometer

The resistance change of the exponential potentiometer has an exponential relationship with the change of the position of the moving contact. Exponential potentiometers have uneven distribution of conductive materials on the resistor body. When the potentiometer starts to rotate, the resistance changes slowly, and when the rotation angle reaches the second half of the stroke, the resistance changes quickly. Exponential potentiometers are suitable for volume adjustment circuits, because the human ear is the most sensitive to sound loudness. When the volume reaches a certain level, the human ear’s hearing becomes gradually dull. Therefore, the volume adjustment generally uses an exponential potentiometer to make the sound change appear stable and comfortable.

2) Characteristics of resistance change of logarithmic potentiometer

The resistance change of the logarithmic potentiometer has a logarithmic relationship with the change of the moving contact position. The logarithmic potentiometer has uneven distribution of conductive materials on the resistor body. When the potentiometer starts to rotate, the resistance changes quickly, and when the rotation angle reaches the second half of the stroke, the resistance changes slowly. Logarithmic potentiometers are suitable for electronic circuits that are contrary to the requirements of exponential potentiometers, such as contrast control circuits and tone control circuits for televisions.

3) Characteristics of linear potentiometer resistance change

The resistance change of the linear potentiometer has a linear relationship with the change of the moving contact position. The conductive material on the resistor body of the linear potentiometer is evenly distributed, and the resistance value per unit length is approximately the same. It is suitable for occasions that require uniform adjustment (such as a voltage divider).