Potentiometer function and use working principle

A potentiometer is an adjustable electronic component. It consists of a resistive body and a rotating or sliding system. When a voltage is applied between the two fixed electric shocks of the resistor body, the position of the contact on the resistor body is changed by a rotating or sliding system, and between the movable contact and the fixed contact, a position that is consistent with the position of the movable contact can be obtained. voltage of a certain relationship.

Potentiometers are mostly used as voltage dividers, which is that the potentiometer is a four-terminal element.

Introduction to Potentiometers

Potentiometers are basically sliding rheostats. There are several styles. They are generally used in speaker volume switches and laser head power adjustments.

A potentiometer is an adjustable electronic component. It consists of a resistive body and a rotating or sliding system. When a voltage is applied between the two fixed electric shocks of the resistor body, the position of the contact on the resistor body is changed by a rotating or sliding system, and between the movable contact and the fixed contact, a position that is consistent with the position of the movable contact can be obtained. voltage of a certain relationship.

Potentiometers are mostly used as voltage dividers, which is that the potentiometer is a four-terminal element.

Potentiometer Structural Features

The resistor body of the potentiometer has two fixed ends. By manually adjusting the shaft or the sliding handle and changing the position of the movable contact on the resistor body, the resistance value between the movable contact and any fixed end is changed, thereby changing the magnitude of voltage and current.

Potentiometer naming and labeling

1. The naming rules of potentiometers are the same as those of resistors, except that they start with the letter W.

2. Marking method of potentiometers: Potentiometers generally adopt the direct labeling method. Letters and numbers are used on the potentiometer shell to mark their model, nominal power, resistance value, and the relationship between resistance value and rotation angle. For example: WT-Ⅱ-1-1k-X potentiometer is expressed as a single carbon film potentiometer type II, the power is 1W, the resistance value is 1kΩ, and the curve is linear.

Potentiometer classification and model

1. Classification by resistor body material:

1. Wire-wound potentiometer: Its resistor body is made of resistance wire wound on a metal or non-metal plate coated with insulating material.

It can be divided into general-purpose, precision, high-power, pre-debugged wirewound potentiometers - the model is WX;

2. Non-wire wound potentiometer: It can be divided into solid potentiometer and membrane potentiometer.

Solid potentiometer: it can be divided into ① organic synthesis - WS, ② inorganic synthesis - WN, ③ conductive plastic - WD;

Membrane potentiometer: It can be divided into ① carbon film potentiometer - WT, ② metal film potentiometer - WJ.

2. Classification by adjustment method: ①Rotary type, ②Push-pull type, ③Straight sliding potentiometer

3. Classification according to the changing law of resistance value: ①Linear type, ②Exponential type, ③Logarithmic type

4. Classification according to structural characteristics: single-turn, multi-turn, single-connection, double-connection, multi-connection, tap type, with switch, locking type, non-locking type, SMD potentiometer;

5. According to different driving methods: ① Manual adjustment potentiometer, ② Electric adjustment potentiometer.

6. Other classification methods: ①Common, ②Magnetic, ③Photosensitive, ④Electronic, ⑤Step Potentiometer.

Potentiometer to judge whether it is good or bad

The main requirements for the potentiometer are: 1. The resistance value meets the requirements. ②The contact between the center sliding end and the resistor body is good, and the rotation is smooth. For potentiometers with switches, the switch part should be accurate, reliable and flexible. Therefore, the performance of the potentiometer must be checked before use.

(1) Measurement of resistance value: First, according to the resistance value of the potentiometer to be measured, select the appropriate resistance gear of the multimeter, measure the resistance value, that is, the resistance value between the two ends of the AC, and compare it with the nominal resistance value. See if the two are consistent. Rotate the sliding contact at the same time, its value should be fixed. If the resistance is infinite, the potentiometer is damaged.

(2) Then measure the contact between its central end and the resistor body, that is, the resistance value between the two ends of BC. The method is that the ohm gear of the multimeter is in the appropriate range. During the measurement process, slowly rotate the shaft and pay attention to the reading of the multimeter. Under normal conditions, the reading changes smoothly in one direction. Bad contact failure.

(3) When the center end slides to the head end or end, ideally, the resistance value of the center end and the coincident end is 0. In actual measurement, there will be a certain residual value (generally depends on the nominal value, generally less than 5Ω), which belongs to normal phenomenon.

Potentiometer function

The main functions of the potentiometer in the circuit are as follows:

1. Used as a voltage divider

The potentiometer is a continuously adjustable resistor. When the handle or slide of the potentiometer is adjusted, the movable contact slides on the resistor body. At this time, the output voltage of the potentiometer can be obtained in a certain relationship with the applied voltage of the potentiometer and the rotation angle or stroke of the movable arm.

2. Used as a varistor

When the potentiometer is used as a varistor, it should be connected as a two-terminal device, so that a smooth and continuously changing resistance value can be obtained within the stroke range of the potentiometer.

3. Used as a current controller

When the potentiometer is used as a current controller, one of the selected current outputs must be a sliding contact terminal.

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