Introduction

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Potentiometers

Potentiometers are variable resistors which function to change their resistance using a knob or dial.

You have probably used one before by adjusting the volume on your stereo or using a light dimmer.

Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment.

Potentiometer is defined as a 3 terminal variable resistor in which the resistance is manually varied to control the flow of electric current.

Potentiometers have a range of resistance.

They can be attuned from zero ohms to whatever maximum resistance that is specific to it.

For example, a potentiometer of 10 kΩ can be adjusted from 0 Ω to its maximum of 10 kΩ.

Symbol of potentimeter

Potentiometer Types

There are two main types of potentiometers:

  • Rotary potentiometer
  • Linear potentiometer
  • Although the basic constructional features of these potentiometers vary, the working principle of both of these types of potentiometers is the same.

    ROTARY POTENTIOMETERS

    The rotary type potentiometers are used mainly for obtaining adjustable supply voltage to a part of electronic circuits and electrical circuits.

    The volume controller of a radio transistor is a popular example of a rotary potentiometer where the rotary knob of the potentiometer controls the supply to the amplifier.

    This type of potentiometer has two terminal contacts between which a uniform resistance is placed in a semi-circular pattern.

    The device also has a middle terminal which is connected to the resistance through a sliding contact attached with a rotary knob.

    By rotating the knob one can move the sliding contact on the semi-circular resistance.

    The voltage is taken between a resistance end contact and the sliding contact.

    The potentiometer is also named as the POT in short. POT is also used in substation battery chargers to adjust the charging voltage of a battery.

    There are many more uses of rotary type potentiometer where smooth voltage control is required.

    Linear Potentiometers

    The logic is pretty much same as the above potentiometer the only difference is that here instead of rotary movement the sliding contact gets moved on the resistor linearly.

    Here two ends of a straight resistor are connected across the source voltage.

    A sliding contact can be slide on the resistor through a track attached along with the resistor.

    The terminal connected to the sliding is connected to one end of the output circuit and one of the terminals of the resistor is connected to the other end of the output circuit.

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    This type of potentiometer is mainly used to measure the voltage across a branch of a circuit, for measuring the internal resistance of a battery cell, for comparing a battery cell with a standard cell and in our daily life, it is commonly used in the equalizer of music and sound mixing systems.

    APPLICATIONS FOR POTENTIOMETER

    Potentiometers are used in a very wide range of industries and applications; it would be difficult to list all applications here. It can be used as a control input, position measurement or calibration component and much more.

  • User controlled inputs:Where a variable input from the user of a machine or application is required, potentiometers are often used.
  • Audio control: Volume control is often performed with a potentiometer in audio applications.
  • Position or angle transducer: Potentiometers are often used as a position or angle transducer to measure distances or angles.
  • Calibration and tuning In fabrication and calibration, trimpots are often used. Trimpots are preset potentiometers which are often mounted on a circuit board and can be used to tune or adjust the circuits performance.
  • PINOUT

    INTERFACING DIAGRAM

    This circuit will be functioning in a way that the light intensity of a LED will be increased or decreased as we vary the resistance using potentiometer.

    CODES

    
          //The following lines define the pins & variables we'll be using 
          int potPin = 2;
          int ledPin = 8;
          int val=0;
          void setup() {
            pinMode (ledPin, OUTPUT);//Sets the LED pin as an output
          }
          void loop() {
            val = analogRead(potPin); //reads the analogue voltage from the pot via ADC and stores it in the variable
            digitalWrite(ledPin, HIGH); //turn the LED output pin high turning the LED on 
            delay(val); //waits an amount of time dependent on the potentiometer position
            digitalWrite(ledPin, LOW); //turn the LED output pin low turning the LED off
            delay(val); //waits an amount of time dependent on the potentiometer position
          }   
          

    I really hope you find this tutorial helpful, and that you understand the use of potentiometer in our daily life!