Internal structure and functional use of precision potentiometer

Precision potentiometer, also known as precision adjustable potentiometer, is a variable resistor that can adjust its own resistance with high precision. Divided into methods such as with pointers and without pointers, adjusting the number of turns includes 5 turns, 10 turns, etc. In order to help you fully understand, this article will summarize the relevant knowledge of precision potentiometer. If you are interested in the upcoming content of this article, please continue reading.

Efficacy of precision potentiometer

1. Act as an inductor or capacitor in high-frequency signals. Inductance (related to external circuit characteristics) is typically used to address EMC issues.

2. When the parameters of the paired circuit are uncertain, use 0ohm instead. When adjusting theoretically, determine the parameters, and then use fine value components instead.

3. When wiring, assuming that it really cannot be connected, a 0ohm resistor can be added (I think it should be inserted directly, not with a meter).

4. When measuring the current consumption of a certain part of the power supply, the 0ohm resistor can be removed and an ammeter can be connected to facilitate the measurement of current consumption.

5. There are no functions in the circuit, just for the convenience of PCB adjustment or adaptation to the design.

6. Make a jumper, assuming that a certain section of the line does not need it, you can directly subsidize the resistance.

Functions of precision potentiometer components

1. The resistance body is the resistance component that provides a certain resistance in the precision potentiometer, and its electrical performance determines the important electrical performance of the potentiometer. Resistors generally have good resistance stability, small resistance temperature coefficient, and static noise. To improve stability, it also has characteristics such as water resistance, heat resistance, wear resistance, oxidation resistance, high load resistance, and resistance to sudden changes in cold and heat.

Brush, scroll Q, and center touch circle.

Potentiometer rolls along the resistance body, and the moving contact component that leads out the input voltage is called brush or contact brush, which is divided into two types: one is metal brush. Electric brushes made of metal materials; Another type is carbon brush, which is made of a mixture of materials such as carbon morning, drowning, and tree fingers. The shapes of metal brushes include brush shape, point shape, spherical shape, and regular finger shape. In terms of ensuring touch stability and uniform current distribution, it is usually referred to as the best brush effect. The shape of carbon brush includes cone and rectangle, the contact surface includes plane sum sphere, contact stability of potentiometer, low noise, mechanical durability and service life, which are directly related to the contact state and mechanical wear of brush resistor body. In order to achieve low circuit resistance and good wear resistance, the brush and resistor body are always in contact and friction state. If combined improperly, one of the two may quickly wear out. Therefore, brush materials have the characteristics of corrosion resistance, oxidation resistance, heat resistance, cold resistance, good heat transfer, good conductivity, non magnetism, low circuit resistance, high wear resistance, and good impact toughness.

2. Frame and substrate

The frame is an insulating support for the resistance body of the wire wound potentiometer. The base plate (or base plate) is the support of the resistor body of the precision wire wound potentiometer.

The frame and substrate are generally made of materials with good insulation performance, which have good heat resistance, water resistance, electrical insulation, chemical resistance, and heat transfer, and only have a certain impact toughness. Generally, there are surface insulation metal substrates such as laminated cardboard, laminated cloth board, plastic, porcelain, glass, copper, aluminum, aluminum alloy, etc., which have sufficient surface insulation. The frame substrate has good heat emission and is easy to form.

3. Touching the reed

The touch reed is a channel piece that connects the brush and the current collector, transmitting the electrical output of the brush to the current collector and the lead wire. The touch reed is a dynamic contact connection with the current collector, so the touch reed has a great impact on the mechanical durability, touch stability and dynamic noise of the potentiometer. Therefore, touch springs usually have good elasticity to ensure that the collecting components have a certain elastic pressure, as well as good conductivity and heat transfer. Their hardness and wear resistance should be consistent with the collecting components. Phosphor bronze and coated brass are common materials. Touch springs are usually integrated with brushes or rolling arms.

4. Outgoing end and current collector

1. The lead out end is a component that connects the two fixed ends of the resistor body and a variable end of the brush to the external circuit. Precision potentiometer with switch also has switch to lead out Rui. The tap potentiometer also has a tap lead out terminal, which is a point in the effective electric stroke where the wiring is led out. All leads and interiors should have good electrical connections. The leading-out end should have good conductivity, corrosion resistance, and oxidation resistance, as well as good bending resistance, tensile impact toughness, and malleability.

2. The current collection component is an electrical connection component between the outlet end and the touch spring. The current collection components have excellent conductivity, low circuit resistance with touch springs, high impact toughness, and good wear resistance. The current collecting parts of the metal glass glazed precision potentiometer shall be formed on the porcelain substrate, and the current collecting parts of the organic synthesis precision solid potentiometer can be suppressed by low resistance conductive powder.

5. Base and housing

1. The base is the basic component for installing and supporting the resistor body, leading out and collecting components. A base made of ordinary porcelain, plastic, or metal materials. Common metal glass glaze, metal film and high-power wire wound potentiometer porcelain base; Aluminum alloy commonly used for precision wire wound potentiometer base. Plastic is easy to be made into various shapes, mechanical and electrical properties, low price, light weight, corrosion resistance, and is widely used in organic synthetic cores, carbon film generation, and general precision wire wound potentiometer.

2. The enclosure is the enclosure for packaging and protecting the main components of the precision potentiometer, which can maintain the internal components, prevent pollution and moisture. Plastic shells are also commonly used for grounding and shielding to prevent the influence of external electric fields.

6. Switch, sliding steel, screw and axle plug

1. The rotating shaft, sliding handle and screw rotating shaft are the rotating parts of the rotary potentiometer; the sliding handle is the linear potentiometer part of the linear motion; The screw is a multi turn rotating part of the screw driven potentiometer. They form a transmission mechanism with other sliding contact components or rotating components. The transmission mechanism is a general term that introduces mechanical motion from the outside and drives the moving contact (brush) to roll along the resistance body. It is called the rotating system in the rotating potentiometer and the rolling system in the straight sliding potentiometer.

The rotating shaft has high machining accuracy and smoothness to ensure smooth rotation or rolling, good feeling, and low working noise. It also has a certain degree of impact toughness to ensure that deformation and fracture do not occur when the transmission force is too large.

2. In the fast precision potentiometer, the shaft sleeve and rotating shaft have high precision, small friction and long rotating life. The safety cylinder that maintains precise motion coordination can form the entire rest component with the base. Generally speaking, threaded shaft sleeves also serve as installation components.

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