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ホーム > Analog technology > Potentiometer: Pinout, Symbol, Wiring, and Working

Potentiometer: Pinout, Symbol, Wiring, and Working

更新時間: 2024-03-21 11:50:12

Contents

A potentiometer is a variable resistor equipped with three pins. Three pins, rather than the conventional two, might confuse beginners in electronics. However, once the internal structure is revealed, the rationale becomes clear. This article delves into potentiometer pinout, symbol, types, and provides examples of wiring configurations for diverse circuits.


10K Potentiometer.png

10K Potentiometer


What Is a Potentiometer?


Potentiometers serve as adjustable resistors within circuits, finding application in various scenarios such as volume control in amplifiers, brightness adjustment in lighting systems, and more.


While resembling resistors, potentiometers offer a unique feature. Unlike resistors with fixed resistance values, potentiometers enable the adjustment of resistance values.


Typically featuring three pins, the schematic symbol for a potentiometer is represented as follows:


potentiometer schematic symbol.jpg


However, using all three pins is not mandatory; utilizing just two pins is perfectly acceptable.


Understanding its construction will clarify this, or you can directly explore wiring examples at the end for practical demonstrations on connecting a potentiometer.




Potentiometer Symbol


There are two symbol representations for potentiometers: the American Standard and the International Standard. While the International Standard symbol is a newer introduction, the American Standard symbol continues to be prevalent in many reference materials.


Potentiometer Symbol (American Standard):


In the American Standard, the potentiometer symbol is characterized by a zigzag line resembling a resistor symbol, accompanied by an arrow positioned above it.


Potentiometer Symbol (International Standard):


Following the International Standard, the potentiometer symbol is a rectangular box featuring two terminals on either side and an arrow positioned in the center.


Potentiometer Symbol.jpg


Potentiometer Pinout


potentiometer-pinout.png

10k Potentiometer Pin Diagram


10K Potentiometer Pin Configuration


Pin No.Pin NameDescription
1Fixed EndThis end is connected to one end of the resistive track
2Variable EndThis end is connected to the wiper, to provide variable voltage
3Fixed EndThis end is connected to another end of the resistive track


The pin configuration of the potentiometer varies depending on the type of potentiometer, whether it's sliding, rotating, or trim.


Single-turn potentiometer Pinout


Single-turn-potentiometer-pinout.jpg


This rotary potentiometer is widely employed and allows rotation in a single direction by turning its knob.


Trimpot Pinout


Trim-potentiometer-pinout.jpg


These pots feature a resistive cement or carbon composition track embedded in circuits for fine-tuning supply voltage. Adjustments to the rotary wiper can be made with a small-bladed screwdriver.


Trimpot Pin Configuration


As an adjustable potentiometer, the trimpot is equipped with three pins, each serving distinct purposes. The configurations of these pins vary based on their positioning in power connections.


  1. Fixed Terminal 1 (CW): This serves as one of the fixed points on the trimpot, linking to a specific point on the variable resistor.

  2. Terminal 2 (Wiper): Connecting to the variable knob on the trimpot, this pin facilitates varied resistance adjustments. It is also linked to components such as LEDs or other output elements.

  3. Fixed Terminal 3 (CCW): This provides another fixed point, forming the opposite terminal of the resistive material.


Multi-turn Trimpot Pinout


Trim-potentiometer-pinout.jpg


Distinguished by its ability for multiple rotations, this model provides enhanced precision compared to its single-turn counterpart.


Skeleton Trimpot Pinout


Skeleton-Trim-potentiometer-pinout.jpg


As its name implies, this trimpot lacks an outer casing and allows resistance adjustment using a screwdriver.


Dual Gang potentiometer Pinout


Dual-gang-potentiometer-pinout.jpg


Comprising two single-turn potentiometers on a single shaft, dual-gang potentiometers use parallel channels to achieve dual functionality.


Servo potentiometer Pinout


Servo-potentiometer-pinout.jpg


Tailored for servo motors, these pots automatically regulate the supplied voltage. A representation of a servo pot is depicted in the figure below.


Sliding potentiometer Pinout


Sliding-potentiometer-pinout.jpg


Referred to as faders, these linear sliders, crafted from conductive plastic, function as sliding potentiometers.


How Potentiometers are Made?


A potentiometer consists of a resistive material strip, typically a carbon mixture, along with an adjustable wiper positioned somewhere on the strip.


inside-potentiometer.png


Each end of the strip connects to a pin, and the wiper is linked to the middle pin. The wiper makes contact with the strip between its two ends, and the wiper's position determines the resistance between the wiper and the side pins. Rotating the potentiometer shaft changes the point where the wiper connects to the carbon strip.


inside-potentiometer-explanation.png


The resistance between the middle and left pins decreases when the wiper is moved to the left side. In contrast, the resistance between the middle and right pins increases—conversely, driving the wiper to the right yields the opposite effect.


Upon purchasing a potentiometer, you must select a specific value, such as 100k. This value represents the measured resistance between the two end pins and signifies the maximum resistance achievable with the potentiometer.


Potentiometer Types


Rotary Potentiometer


This is the most prevalent type, featuring a turntable shaft that alters the resistance as it is rotated. It is commonly employed for volume adjustments in guitar pedals, audio amplifiers, and other audio devices. The values of this potentiometer can exhibit linear or exponential changes, with the exponential version often utilized for audio volume adjustments.


Rotary Potentiometer.jpg


Dual or Stereo Potentiometer


Like the rotary potentiometer, the dual or stereo potentiometer integrates two potentiometers controlled by a single shaft. This configuration facilitates the simultaneous control of two channels in a stereo system, such as the left and right channels.


Dual or Stereo Potentiometer.png


Linear or Slide Potentiometer


The slide or linear potentiometer has a slider or wiper that moves in a straight line, changing the resistance accordingly. Commonly found in audio mixing consoles, these potentiometers are used as faders.


Linear or Slide Potentiometer.jpg


Trimmer or Trimpot


A trimmer potentiometer, also known as a "trimpot," is small and typically employed for occasional adjustments, such as during setup or calibration. It is often mounted on PCBs and adjusted using a small screwdriver.


Trimmer or Trimpot.png


Digital Potentiometer


The digital potentiometer is a chip that allows you to modify the wiper's position through digital signals like SPI or I2C. This can be particularly useful when dynamic resistance adjustments are needed, such as altering LED brightness from an Arduino or other microcontroller.


Digital Potentiometer.png


Potentiometer Wiring Examples


The method of wiring a potentiometer is contingent on its intended application.


Typically, the middle pin serves as the wiper. Rotating the shaft (or sliding the slider) to the right diminishes the resistance between the wiper and the right pin. Conversely, moving it to the left reduces the resistance between the left pin and the wiper.


In some scenarios, utilizing all three pins is practical, while only two pins are necessary in other instances. Let's delve into a few examples.


Potentiometer as a Simple Variable Resistor


If you require a primary adjustable resistor, utilizing only two pins suffices the middle pin and one of the side pins.


led-potentiometer-circuit.png


The diagram above illustrates a straightforward circuit for dimming a Light-Emitting Diode (LED). In an actual circuit, it's advisable to include an additional resistor in series to safeguard the LED, even if adjusted to the point where the resistance approaches zero.


Rotate the shaft in one direction, and the resistance augments, causing the LED to dim. Conversely, turning it in the opposite direction reduces the resistance, brightening the LED.


Connecting the Third Pin to the Middle


Occasionally, you might encounter circuit diagrams where the middle and bottom pins are linked to the same junction. Why?


laser-diode-constant-current.png


This method of connection is essentially equivalent to utilizing only two pins. Attaching the third pin to the middle pin doesn't impact the resistance.

So, why adopt this approach?


Some individuals favor this configuration as they find it tidier, avoiding an unconnected pin. Additionally, it contributes to a more aesthetically pleasing circuit diagram.


Potentiometer as Volume Control


In this illustration, all three pins of the potentiometer are employed to establish an uncomplicated method for adjusting the volume of an audio amplifier.


potentiometer-wiring-volume-control.png


By configuring the connection in this manner, a voltage divider is formed, diminishing the input signal's voltage. As you rotate the shaft, the volume decreases correspondingly.


This wiring arrangement is widely employed in various audio equipment.


How to Select a Potentiometer?


Potentiometers, often referred to as POT, are essentially variable resistors that offer adjustable resistance by manipulating the knob located on top of their housing. They are categorized based on two primary parameters: resistance (measured in ohms, denoted as R) and power (measured in watts, denoted as P).


The resistance value determines the level of opposition it presents to the current flow. A higher resistor value results in reduced current flow. Common standard values for potentiometers include 500Ω, 1K, 2K, 5K, 10K, 22K, 47K, 50K, 100K, 220K, 470K, 500K, and 1 M.


Resistors are also classified according to their power or wattage rating, indicating the amount of current they can accommodate. A higher power rating corresponds to a larger resistor that can handle more current. The power rating is typically 0.3W for potentiometers, making them suitable for low-current circuits.


How to Use a Potentiometer?


In the realm of resistors, the norm is to encounter components with two terminals. However, the uniqueness of a potentiometer lies in its possession of three terminals, prompting questions about their purpose and how they are utilized. Understanding the functionality of these terminals becomes clear when examining the provided diagram.


Potentiomter-working.png


The diagram illustrates the internal components of a potentiometer. Within it is a resistive track, and the total resistance matches the rated resistance value of the potentiometer.


Symbolically, a potentiometer can be visualized as a resistor with one variable end. For instance, consider a 10k potentiometer. If we measure the resistance between terminal 1 and terminal 3, the reading will be 10k, as both terminals represent fixed ends of the potentiometer. Now, with the wiper positioned precisely at 25% from terminal 1, measuring the resistance between 1 and 2 yields 25% of 10k, equating to 2.5K. Simultaneously, measuring across terminal 2 and 3 provides a resistance of 7.5K.


Hence, terminals 1 and 2, or terminals 2 and 3, offer a means to obtain variable resistance, with the knob facilitating the adjustment of resistance to achieve the desired value.


Conclusion


In conclusion, any electronics enthusiast or engineer must understand the pinout, wiring procedures, working principles, and practical applications of potentiometers. By following these guidelines, one can harness the full potential of potentiometers in various electronic circuits.


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FAQ

  • Which way do you wire a potentiometer?
  • Typically, potentiometers are connected as variable voltage dividers: link one side to +V, connect the other side to ground, and the middle pin will generate a voltage output ranging from 0 to +V.

  • What are the alternative variable resistors of the 10k potentiometer?
  • Resistors, trimmers, and trim pots.

  • Which pins are which on a potentiometer?
  • A standard potentiometer typically consists of three pins: two for power supply (+5V and GND) and one connecting to an analog input pin.

  • Which pin on the potentiometer is ground?
  • Pins #1 and #3.

  • What is the use of 10k potentiometer?
  • A 10k potentiometer is utilized in voltage and current control circuits, functions as a volume control in radios, is employed for tuning or controlling circuits and serves as analog input control knob.

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