Potentiometer is an adjustable power resistor, and it is also one of the most widely used components in electronic circuits. It has three external terminals, of which two are fixed ends and the other is central tap. Turning or adjusting the rotation axis of the potentiometer, the resistance between the center tap and the fixed end will change.

Performance indicators of potentiometers

The performance indicators of bourns potentiometer and adjustable power resistor are identical in nominal resistance, allowable deviation, rated power and so on. In addition, there are the following indicators.

1. Change regulation of resistance

The resistance variation rule refers to the relationship between the rotation angle (or stroke) of the bourns potentiometer and the output voltage when used as a divider. The resistance of common potentiometers varies linearly, exponentially, and logarithmically.

2. Sliding noise

When the brush slips on the resistance body, the voltage between the center end of the bourns potentiometer and the fixed end is irregular. This phenomenon is called the sliding noise of the potentiometer. It is caused by the uneven distribution of material resistivity and the irregular change of contact resistance when the brush is slipping.

3. Resolution

The finest adjustment ability of output can be achieved. The resolution of the wire - wound potentiometer is poor.

4. Limit voltage

The highest voltage that a potentiometer can withstand in a short period of time.

5. Mechanical durability

Usually the number of times of rotation (or sliding) is the indicator of the service life of potentiometers.


Types and specifications of several commonly used potentiometers

1. Organic solid core potentiometer

Resistance powder is made of conductive material, organic filler and thermosetting resin. After hot pressing, solid core adjustable power resistor is formed on the base. The potentiometer is characterized by its simple structure, high temperature resistance, small volume, long life and high reliability. It is widely used for welding on the circuit board for micro adjustment, and the shortcoming is low pressure resistance and large noise.

2. Wire wound potentiometer

The resistance wire is wound on the insulating skeleton by the alloy resistance wire, and the reed of the center tap slides on the resistance wire. The wire wound potentiometer is widely used, and can be made into ordinary, precision and fine tuned potentiometers, and the rated power is larger, the temperature coefficient of the resistance is small, the noise is low, and the pressure is high.

3. Synthetic film potentiometer

A layer of synthetic carbon film is coated on the insulating substrate. After heating polymerization, the carbon membrane is formed and combined with other parts. This type of potentiometer has continuous resistance, high resolution, wide resistance range and low cost. But it has poor adaptability to temperature and humidity and short service life.

4. Multi loop potentiometer

The multi loop potentiometer belongs to the precision potentiometer. It consists of pointer, pointer and so on. There are 5 circles and 10 circles to adjust the number of circles. In addition to the same characteristics of the wire wound potentiometer, the potentiometer has the advantages of good linearity and fine adjustment. It can be widely used in the precise adjustment of resistance.