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Introduction to Variable Resistor



In this tutorial, we will learn how to control the brightness of a LED using potentiometers(Variable Resistor).
A potentiometer also known as the pot is a three-terminal resistor with sliding or rotating contact that forms an adjustable voltage divider, they can be also used as a rheostat or variable resistors.
Broadly there are two types of potentiometers available.
  •          The Rotary Pot - they use a rotary motion to move the slider around a track that compromises most of a circle, with contacts at either end of the track in the area where part of the circle is missing.They are widely used in appliances with knob control.
 
  •      The Sliding Pot -- they are those variable resistors that slide in a linear fashion,i.e in a straight line.These controls take up more front panel space but are much easier to use under some circumstances. for example, they are widely used for audio mixers and lighting desks.
      
 Now we know how a pot works let us have some fun with it
Components required
  • Resistor 1No. 330 ohms.
  • Arduino UNO 1No.
  • Potentiometer 1No.
  • Connecting wires.
For the circuit, reference follows the video below.
We have used a multimeter to make you understand how the voltage varies with resistance it’s an optional component.
After making the circuit dump the code given below and observe the output.

int led = 9;
int pot=A0;
int d,e;
void setup() 

{
Serial.begin(9600);
}
void loop()
{
d=analogRead(pot);
Serial.println(d);
e=d/4;
analogWrite(led, e);
}

  •   We can reverse the rotating function of a potentiometer by interchanging the VCC and GND supply pins. 
  •   In Arduino UNO A0-A5 pins can be used to read analog values like that of pot and pin no. 3,5,6,9,10,11 can be used as digital pins.
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