It is a light dimmer circuit. The function of this circuit is very simple. It gradually increases as well as decreases the light intensity of Light Emitting Diode(LED). In this circuit we are using some basic components such as LED,Potentiometer,Resistor. Potentiometer is a device which is also known as variable resistor. The value of its resistance is varied by using its knob. It is a three terminal device. Value of resistance of potentiometer is from 0 to maximum value which is normally written on the potentiometer. In this circuit we are using potentiometer to change light intensity of LED.

 Circuit Diagram:

 Component Values:

  • Potentiometer : R1= 100 Kilo Ohm
  • Resistor : R2 = 100 Ohm
  • Color Code for 100 Ohm : Brown-Black –Brown-Golden
  • Light Emitting Diode: LED1
  • Battery : 9 Volts

Circuit Building Steps:

Step 1:

Mount LED 1 on bread board. Connect Anode of LED 1 to VCC and connect Cathode to vertical slot of bread broad as shown below:

Step 2:

Connect Potentiometer R1 of 100k ohm on bread board.

Step 3:

Connect resistor R2 on bread board as shown below.The value of R2 is 100 ohm.

Step 4:

Now connect wires of potentiometer. Connect red wire to the cathode of LED. Connect brown and black wires to the one terminal resistor R2. connect second terminal of R2 to the ground through black wire.

Step 5:

Connect battery terminals to the bread board circuit and observe the output.

When we give the power supply to the circuit LED will turn ON.  We have to vary potentiometer knob  to observe the change in  light intensity of LED. When potentiometer reaches to its maximum resistance value at that time very small current flows through the circuit which is not sufficient to turn ON LED,hence LED remains OFF. When potentiometer reaches to its minimum value LED will glow with  maximum light intensity.