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For the choice of potentiometer, it is first necessary to clarify the purpose and design purpose. If used as a volume control, the logarithmic potentiometer should be selected. For example, if you need to control the power on and off, you should select the potentiometer with the switch. When used as a partial pressure tone control, an exponential potentiometer should be selected. Linear potentiometers are often used in negative feedback circuits or circuits that require uniform voltage regulation.
Trimmer potentiometers are often used as transistor bias current adjustments or as variable resistors in electronic circuits. The stereo sound response uses a double potentiometer. The correction circuit should use a potentiometer with a locking device. Regardless of the potentiometer selected, the main technical parameters, such as rated power (W), nominal resistance range (kΩ), maximum operating voltage (V), switch rated current, and linear form, should meet the circuit requirements.
Potentiometer types and characteristics
Synthetic carbon film potentiometer
Synthetic carbon film potentiometers are currently the most used potentiometers. The resistor body is made of a mixture of carbon black, graphite, quartz powder, organic binder, etc., and is coated on a rubber board or a fiberglass board. The advantages are high resolution and wide resistance range. The disadvantage is that the sliding noise is large and the heat and humidity resistance is not good. Variety: Common synthetic carbon film potentiometer, small synthetic carbon film potentiometer with switch, single-band switch (no switch) potentiometer, double coaxial no switch (with switch) potentiometer, double-axis independent switch ( With switch) potentiometer, small precision synthetic carbon film potentiometer, push-pull switch synthetic carbon film potentiometer, straight-slip synthetic carbon film potentiometer, precision multi-turn synthetic carbon film potentiometer.
Wirewound potentiometer
The resistor body is made of a resistance wire wound around a metal or non-metal plate coated with an insulating material. Advantages: high power, low noise, high precision, good stability; disadvantages: poor high frequency characteristics.
Metal film potentiometer
The resistor body is formed by depositing a metal alloy film, a metal oxide film, a metal composite film, and a ruthenium oxide film material on a ceramic substrate by a vacuum technique. Advantages: high resolution, sliding noise is smaller than synthetic carbon film potentiometer; disadvantages: small resistance range, poor wear resistance.
Straight slide potentiometer
The resistor body has a rectangular strip shape, and the resistance value is changed by linear movement of the slider connected to the slider. Uses: Generally used for volume control or equalization control in TV sets and stereos.
Single-turn potentiometer and multi-turn potentiometer
The sliding arm of the single-turn potentiometer can only be rotated within a range of less than 360 degrees, which is generally used for volume control. For each revolution of the multi-turn potentiometer, the sliding arm contact changes only a small distance on the resistor body, and the rotating shaft needs to rotate a plurality of turns when the sliding arm is from one extreme position to the other extreme position. Generally used in precision adjustment circuits.
Solid potentiometer
It is made by mixing materials heated with carbon black, graphite, quartz powder, organic binder, etc., and then pressed on a plastic substrate and then heated and polymerized. Advantages: high resolution, good wear resistance, wide resistance range, high reliability and small volume; disadvantages: high noise and poor high temperature resistance. Can be divided into small solid potentiometers, linear solid potentiometers, logarithmic solid potentiometers.
Single potentiometer and double potentiometer
The single potentiometer controls a set of potentiometers by a separate rotating shaft; the double potentiometer usually mounts two potentiometers of the same specification on the same rotating shaft. When the rotating shaft is adjusted, the sliding contacts of the two potentiometers rotate synchronously. Suitable for volume adjustment of two-channel stereo amplifier circuits. There are also some double-connected potentiometers that are asynchronous.
Step potentiometer
It consists of a stepping motor, a shaft resistor, a moving contact, and the like. The moving contact can be manually adjusted by the rotating shaft or by a stepping motor. Uses: Used for volume control in audio power amplifiers.
Switch potentiometer
A switching device is attached to the potentiometer. The switch is coaxial with the potentiometer, and the movement and control mode of the switch are divided into two types: rotary type and push-pull type. Uses: Used for volume control and power switch in black and white TV sets. The small rotary type with potentiometer is mainly used for volume control (or current, voltage regulation) and power switch in semiconductor radio or other small electronic products. The number of switch positions is single pole single throw, single pole double throw and double pole single throw.
SMD potentiometer
Also known as a chip potentiometer, it is an ultra-small linear potentiometer without a manual rotating shaft. Tools such as a screw driver are required for adjustment. Type: divided into single-turn potentiometer and multi-turn potentiometer - is a precision potentiometer, there are two structures of vertical and horizontal.
This paper introduces the types and characteristics of ten common potentiometers, and gives a detailed explanation of the advantages, disadvantages and divisions of each potentiometer. For beginners, this is an article that is very suitable for use as an introductory study material, but for a little basic friend, this article can also serve as an excellent knowledge reserve.
