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The schematic diagram of the potentiometer and its types

Date:2018-05-24 19:41:35        Hits:1204 
The potentiometer is a commonly used adjustable resistance electronic components. The potentiometer is from the predecessor of the variable resistor is a resistor, usually consists of a resistor body and a brush system. When the brush is subjected to external artificial or mechanical force, the brush will move around the resistor body, and thus at the output end, The resistance value or voltage that is proportional to the amount of movement is obtained. The potentiometer has three terminals, the resistance can be adjusted according to the law. The potentiometer can be used for both three-terminal electronic components and two-terminal electronic components. The latter can be regarded as a variable resistor because its role in the circuit is to obtain a certain relationship with the input voltage (applied voltage) to obtain the output voltage, so it is called a potentiometer.
A wide variety of potentiometers, more common are: ordinary rotary potentiometer, with switch potentiometer, 3D rocker potentiometer, ultra-small potentiometer with the switch, slide potentiometer, multi-turn potentiometer, trimmer potentiometer, double Potentiometers, etc., as shown in Figure (a). The potentiometer's text symbol is "Rp", and the commonly used symbol in the circuit diagram is shown in figure (b).

Potentiometer (English: Potentiometer) is a type of variable resistor. It is usually composed of a six-pin potentiometer resistor body and a rotating or sliding
system, that is, a movable contact is moved on the resistor body to obtain part of the voltage output.
The role of the potentiometer - adjust the voltage (DC or AC voltage) and the size of the current.
Potentiometer structure features - potentiometer resistor body has three fixed ends, by manual shaft press or slide the handle, change the position of the brush
contact on the resistor body, then change the brush and resistor body and output terminal connection The resistance value thus changes the voltage (AC or DC
voltage) and current.
figure (b)
The potentiometer is an adjustable electronic component. It consists of a resistor body and a rotating or sliding system. When a voltage (AC or DC voltage) is
applied between two fixed contacts of the resistor body, the position of the contact on the resistor body can be changed by rotating or sliding the system and can be obtained between the movable contact and the fixed contact. A voltage proportional to the position of the moving contact. It is mostly used as a voltage divider, and the potentiometer is a four-terminal component.The potentiometer is basically a sliding rheostat, only a few styles, generally used in such as speaker volume switch and
laser head power and another fine-tuning efficiency, the potentiometer is an adjustable electronic component.
Variable resistor for voltage division. On the resistor body, one or more movable metal contacts are pressed. The contact position determines the resistance between any one end of the resistor body and the contact. Divided by the coil material, carbon film, solid core potentiometer; according to the power output and input voltage ratio and rotation angle of the relationship between the linear potentiometer (linear relationship), function potentiometer (curve relationship). The main parameters include the allowable error, accuracy, grade, and so on. Widely used in electronic products, hospital equipment, play a role in partial pressure or micro-adjustment to avoid errors;
For the main parameters of the electronic potentiometer:
Potentiometer main parameters in addition to the nominal allowable error, accuracy, grade, there are nominal resistance, sliding noise, rated power, zero resistance, resolution, wear resistance, resistance change characteristics and temperature, etc., potentiometer The resistance has a certain law, and its resistance value changes with the rotation angle or sliding distance of the boom. Ordinary potentiometer resistance change law has exponential (Z type) potentiometer, linear (X type)potentiometer, logarithmic (D type) potentiometer three. The relationship between the three forms of potentiometer resistance and the change of the moving contact curve is shown in Figure (b). In the figure, the ordinate indicates the percentage relationship between the resistance value and the total resistance value of the potentiometer when a certain position and the X coordinate is a percentage relationship between the rotation distance and the maximum distance.
Potentiometer's actual operation and function:
The linear potentiometer, that is, the resistance change of the X-type potentiometer is almost in a straight line relationship with the angular displacement. That is, the conductive material on the resistor body is uniformly distributed on the resistor carrier, and the resistance per unit length is substantially equal. Based on this characteristic, it is determined that it is suitable for use in some products that require uniform regulation, such as sub-throttle control, hydraulics, and hospital equipment. When the Z-type potentiometer starts to twist, its resistance value changes relatively small, and when the angle is close to the maximum end, the resistance value changes more obviously. Because the human ear slightly increases the tiny sound, when the basic person does not feel it but reaches a certain value, even if the power is increased, the human feels but the change is not so great. This potentiometer is suitable for the volume control circuit. The volume control of the potentiometer makes it possible to obtain an approximately linear relationship between volume and potentiometer rotation. The change in the resistance of the D-type potentiometer is the opposite of the Z-shape. The resistance value changes greatly when it starts to rotate, and the resistance value changes more smoothly when the rotation angle is close to the maximum value. D-type potentiometers are suitable for circuits such as tone control. Picture C

(b) Resistance change characteristic
(MEMO) If there is a slight contact with the potentiometer, use pure alcohol to clean the carbon diaphragm and the contacts of the rotor. If the carbon film wears badly in the potentiometer and the contact is bad, you can gently move the metal play contacts inward or outward. Bending outwards, change the movement path of the metal brush on the carbon film; if the potentiometer has a discontinuity between a certain piece and the carbon film (mostly open circuit at the coating station), the other piece is not used or welded together with the rotor plate. At this time, the exchange positions of the two fixed sheets can still be used normally. For example, The potentiometer A is fixed and the carbon membrane is disconnected. At this time, the potentiometer A can be fixed by welding, and B can be changed by welding. If the carbon film wears out, use a pencil to apply carbon on top to keep it in use. Serious damage or conditions allow it to be replaced as new as possible.
Potentiometer type:
First, synthetic carbon film potentiometer: a potentiometer used on the market. Its resistor body is made of carbon black, graphite, quartz powder, organic binder compound mixture and then experience made into carbon film, and other parts combined.
Advantages: high resolution, wide resistance range;
Disadvantages: Poor temperature adaptability, large sliding noise, and poor heat and moisture resistance.
Variety: including precision synthetic carbon film potentiometer, synthetic carbon film potentiometer with switch, single-link switch (no switch) potentiometer, double-conductor switch (with switch) potentiometer, double-axis switch (with Switch) potentiometers, small precision synthetic carbon film potentiometers, straight-slip synthetic carbon film potentiometers, precision multi-turn synthetic carbon film potentiometers, etc.
Second, winding potentiometer: The resistor body is made of resistance wire wound on a metal or non-metal plate coated with insulating material.
Advantages: high power, low noise, high precision, good stability;
Disadvantages: poor high-frequency characteristics.
Third, the metal film potentiometer: The resistor body is made of metal alloy film, metal oxide film, metal composite film, cerium oxide film material deposited on the ceramic substrate by vacuum technology.
Advantages: high resolution, sliding noise smaller than synthetic carbon film potentiometer;
Disadvantages: Small resistance, poor wear resistance.
4. Slide-type potentiometer: The resistor body is a rectangular bar, and the resistance value is changed by the linear movement of the slider connected to the slider.
Uses: Generally used in hospital equipment, televisions, audio for precision control or balanced control.
Fifth, single-turn potentiometer and multi-turn potentiometer:
Single-turn potentiometer: active rotation range less than 360 °, generally used for volume control;
Multi-turn potentiometer: Each time it rotates, the contact point of the slide arm changes only a small distance on the resistor body. When the slide arm moves from one extreme position to the other extreme position, the rotary shaft needs to rotate several times. Generally used in precision regulation circuits.
Six, solid potentiometer: is carbon black, graphite, quartz powder, organic binders and other materials mixed heating, pressure on the plastic substrate, and then heated by polymerization.
Advantages: high resolution, good wear resistance, wide resistance range, high reliability, small size;
Disadvantages: Large noise and poor high-temperature resistance.
 Variety: Can be divided into small solid potentiometers, linear solid potentiometers, logarithmic solid potentiometers.
Seven single potentiometer and double potentiometer:
Single-link potentiometer: A set of potentiometers is controlled by an independent shaft;
Double potentiometer: Usually two potentiometers with the same specifications are mounted on the same shaft. When adjusting the shaft, the sliding contacts of the two potentiometers rotate synchronously, which is suitable for the volume adjustment of the two-channel stereo amplifier circuit. There are also some double potentiometers asynchronous shaft.
Eight, stepping potentiometer: It is composed of stepping motor, rotating shaft resistor body, moving the contact and so on. The movable contact can be manually adjusted via the rotary shaft and can also be driven by a stepping motor.
Uses: Used for volume control in audio power amplifiers
Nine, The with a switch potentiometer: a switch device is added to the potentiometer. The switch and the potentiometer are coaxial, and the movement and control of the switch are divided into two types: rotary and push-pull.
Uses: Used for volume control and power switch in black and white televisions. The small rotary potentiometer with the switch is mainly used for volume control (or current, voltage regulation) and power switch in semiconductor radios or other small electronic products.
Type: Single-pole single-throw, single-pole double-throw, and double-pole single-throw are available for switching.
X. SMD potentiometer: also known as chip potentiometer, is a type of ultra-small linear potentiometer without manual rotation axis, adjust the use of tools such as screwdrivers.
      Eleventh, 3D rocker potentiometer: It is composed of a plurality of parts, including rocker, single ring potentiometer, beam, spring, top and bottom, base, sliding disk and other combinations of rocker potentiometer. Picture D
10.SMD potentiometer: also known as chip potentiometer, is a type of ultra-small linear potentiometer without manual rotation axis, adjust the use of tools such as screwdrivers.
11.3D rocker potentiometer: It is composed of a plurality of parts, including rocker, single ring potentiometer, beam, spring, top and bottom, base, sliding disk and other combinations of rocker potentiometer. Picture E
The role of potentiometer:
The main role of potentiometer equipment is divided into three aspects:
1. As a voltage divider potentiometer is a continuously adjustable resistor element, when the potentiometer handle or sliding handle is pulled, the brush slides on the resistor body. At this point, the output of the potentiometer can be associated with the potentiometer applied voltage and the movable arm rotation angle or stroke and output voltage.
2. When used as a varistor potentiometer as a varistor, it should be connected to both ends of the device, so that within the range of the potentiometer travel, you can obtain a smooth and continuously changing resistance value.
3. Use as a current controller When the potentiometer is used as a current controller, one of the selected current output terminals must be a sliding contact terminal.
Potentiometer pin connection:
The potentiometer is divided into 3 legs, which are used instead of A, B, C instead of A, B and, C. The A pin is grounded, the B pin is connected to the output, and the C pin is connected to the signal input. A pin C pin can be indistinguishable. The general potentiometer, the middle is a moving piece, so if you measure the resistance, then connect the A and C pins to measure the total resistance. The B solution will not change regardless of whether it is moving or not. Connect the A pin, The resistance of the B pin will increase from the clockwise direction (movement of the moving piece); the B pin and the C pin will be reversed!
Double potentiometer connection
6 feet called double potentiometer is 2 single link together!
8-pin potentiometer
The 8-pin potentiometer should be equipped with a switch, which is commonly used on car stereos.

Potentiometer connection diagram
The connection of the three-pin potentiometer, in order to facilitate understanding of the high-Gold electronic set the middle pin to the B pin, the left is called A pin, the right is called C pin
Is the A pin and B pin the same as the B pin and the C pin?
If you are connected to a motor speed control, can you use a three-pin potentiometer and control the motor forward and reverse it? How should I connect?
The feet on both sides of the potentiometer are its full resistance, and the B pin is a sliding node. The power supply is connected from the A pin or C pin and leads out from the middle pin. The voltage that changes with the rotation of the middle pin can be obtained.
The rotational speed of the DC motor varies with the applied voltage, so the rotation of the middle pin changes the voltage and changes the speed of the motor.
Changing the positive and negative power supply of the DC motor can make the motor reverse and the potentiometer does not have this function.
The connection of the 3D rocker potentiometer is the same as the common potentiometer electronic components. It depends mainly on what equipment he is using and how effective it is;