What Is a Potentiometer? Analog Reading and Control with Arduino

A potentiometer is an adjustable resistor whose resistance changes as you turn its shaft. A radio's volume knob, a lamp dimmer and the sticks of a game controller are all potentiometers. In Arduino projects it's the easiest way to get a value from the user: you turn the knob and the Arduino reads a number between 0 and 1023.

How does a potentiometer work?

Inside there's an arc-shaped resistive track and a wiper that slides along it. The resistance between the two outer legs is fixed (for example 10 kΩ). The middle leg is connected to the wiper; as you turn the shaft, the wiper moves along the track and the resistance to each outer leg changes. Put 5 V and GND on the outer legs and you get a voltage between 0 and 5 V on the middle leg. In other words, a potentiometer is an adjustable voltage divider.

Types of potentiometers

Connecting a potentiometer to Arduino

1. Connect one outer leg to 5V and the other to GND (swapping them just reverses the direction).
2. Connect the middle leg to an analog input, for example A0.
3. Connect an LED with a 220 Ω resistor to PWM-capable pin 9.
4. Upload the code below and open the serial monitor; turning the knob changes the value and the LED brightness.

const int POT_PIN = A0;   // potansiyometre orta bacak / pot wiper
const int LED_PIN = 9;    // PWM pini / PWM pin

void setup() {
  pinMode(LED_PIN, OUTPUT); // LED çıkış / LED output
  Serial.begin(9600);       // seri monitör / serial monitor
}

void loop() {
  int raw = analogRead(POT_PIN);              // 0–1023 oku / read 0–1023
  int brightness = map(raw, 0, 1023, 0, 255); // PWM'e çevir / scale to PWM
  analogWrite(LED_PIN, brightness);           // parlaklık / brightness
  Serial.println(raw);                        // değeri yaz / print value
  delay(20);
}

The map() function converts a value from one range to another, like turning a 0–1023 reading into a 0–255 PWM value or a 0–180 servo angle. To see the voltage divider idea in numbers, use the voltage divider calculator.

Analog reading range by board

Common mistakes

• Connecting the middle leg directly to 5V or GND: at the end of its travel this makes a short circuit and can burn the pot. Power always goes to the outer legs.
• Jittery values: readings can wobble by a few units. Average several readings or ignore small changes.
• Using a logarithmic pot: with an A-type pot the value changes slowly at the start and fast at the end; use a B type for linear control.
• Connecting it to a digital pin: a potentiometer gives an analog value, so it must go to an analog input like A0–A5.

You'll find how to set a servo angle with a potentiometer in What Is a Servo Motor?, and the basics of resistance in What Is a Resistor?.