Structural characteristics of potentiometer

　　 (1) Synthetic carbon film potentiometer: It is the most widely used potentiometer. The resistor body is made of carbon black, graphite, quartz powder, organic binder, etc., which is coated on bakelite board or glass fiber board.

　　 Advantages: high resolution, wide resistance range;

　　 Disadvantages: large sliding noise, poor heat and humidity resistance.

Varieties: common synthetic carbon membrane potentiometers, small synthetic carbon membrane potentiometers with switches, single-unit with switch (without switch) potentiometer, double-coaxial without switch (with switch) potentiometer, double-coupled off-axis without switch ( (With switch) potentiometer, small precision synthetic carbon film potentiometer, push-pull switch synthetic carbon film potentiometer, direct sliding synthetic carbon film potentiometer, precision multi-turn synthetic carbon film potentiometer, etc.

　　 (2) Metal film potentiometer: The resistor body is made of metal alloy film, metal oxide film, metal composite film, tantalum oxide film material deposited on the ceramic substrate by vacuum technology.

　　Advantages: high resolution and less sliding noise than synthetic carbon film potentiometer;

　　 Disadvantages: small resistance range, poor wear resistance.

　　 (3) Wire-wound potentiometer: its resistance body is made of resistance wire wound on metal or non-metal plate coated with insulating material.

　　Advantages: high power, low noise, high precision and good stability;

　　 Disadvantages: poor high-frequency characteristics.

　　 Varieties: There are ordinary wire wound potentiometers, ordinary multi-turn wire wound potentiometers, precision multi-turn wire wound potentiometers, straight-slide precision multi-turn wire wound potentiometers, functional precision multi-turn wire wound potentiometers, etc.

　　 (four) solid potentiometer: It is made of carbon black, graphite, quartz powder, organic binder and other materials mixed and heated, pressed on the plastic substrate, and then polymerized by heating.

　　 Advantages: high resolution, good wear resistance, wide resistance range, high reliability, small size;

　　 Disadvantages: high noise and poor high temperature resistance.

　　Variety: It can be divided into small solid potentiometer, linear solid potentiometer, logarithmic solid potentiometer.

　　 (5) Single-turn potentiometer and multi-turn potentiometer:

　　Single-turn potentiometer: its sliding arm can only rotate in the range of less than 3600, generally used for volume control;

　　Multi-turn potentiometer: Every time its rotating shaft turns, the sliding arm contact changes only a small distance on the resistor. When the sliding arm moves from one extreme position to the other extreme position, the rotating shaft needs to turn many times. Generally used in precision adjustment circuits.

　　 (6) Single and double potentiometers:

　　Single-connected potentiometer: a group of potentiometers is controlled by an independent rotating shaft;

　　Double potentiometer: Usually two potentiometers with the same specifications are installed on the same rotating shaft. When adjusting the rotating shaft, the sliding contacts of the two potentiometers rotate synchronously. There are also some duplex potentiometers that are asynchronous and off-axis.

　　 (7) Potentiometer with switch: A switching device is attached to the potentiometer. The switch is coaxial with the potentiometer, and the movement and control methods of the switch are divided into rotary and push-pull types.

　　Usage: mostly used for volume control and power switch in black and white TV. The small rotary potentiometer with switch is mainly used for volume control (or current and voltage adjustment) and power switch in semiconductor radios or other small electronic products.

　　 Type: The number of switches includes single pole single throw, single pole double throw and double pole single throw.

　　 (8) Straight slide potentiometer: its resistor body is rectangular strip shape, it changes the resistance value by linear movement of the slide handle connected with the slide base.

Uses: generally used for volume control or equalization control in TVs and stereos.

　　 (9) SMD potentiometer: Also known as chip potentiometer, it is an ultra-small linear potentiometer without manual rotation axis. Tools such as screwdrivers are required for adjustment.

Type: Divided into 1. Single-turn potentiometer;

          2. Multi-turn potentiometer-it is a precision potentiometer with vertical and horizontal structure.

　　 (ten) stepping potentiometer: It is composed of stepping motor, rotating shaft resistance body, moving contact, etc. The moving contact can be adjusted manually through the rotating shaft, or it can be driven by a stepping motor.

　　Usage: mostly used for volume control in audio power amplifier.

Structural characteristics of commonly used potentiometers 2

Potentiometer

The potentiometer is an adjustable resistor and one of the most widely used components in electronic circuits. It has three external terminals, two of which are fixed and the other is a center tap. Turn or adjust the potentiometer rotating shaft, the resistance between the center tap and the fixed end will change. 2.2.1 Performance index of potentiometer

The meaning of the performance indicators of potentiometers and resistors is the same in terms of nominal resistance, allowable deviation, rated power, etc. In addition, there are the following indicators.

1. Variation of resistance

The change rule of resistance refers to the relationship between the rotation angle (or stroke) of the potentiometer and the output voltage when used as a voltage divider. Common resistance changes in potentiometers are linear, exponential, and logarithmic.

2. Sliding noise

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

3. Resolution

The finest adjustment capability for output. The resolution of the wirewound potentiometer is poor.

4. Limit voltage

The highest voltage the potentiometer can withstand in a short time.

5. Mechanical durability

It is usually marked by how many times it rotates (or slides), which is an indicator of the service life of the potentiometer.

2.2.2 Several commonly used potentiometer models and specifications