Controlling PWM of LED using a potentiometer

Updated: Feb 28

Pulse-width modulation (PWM) is a method of reducing the average power delivered by an electrical signal by changing the duty cycle.

Duty Cycle is defined as the ratio of the digital ' high ' period to the total sample period.

Duty Cycle = Ton/(Ton+Toff)

As you can see in the image above, the average output voltage is zero with 0% duty cycle and it increases with an increase in duty cycle and is maximum at 100% duty cycle.

In this project, we will control the PWM of LED (i.e., illumination intensity can be controlled) by varying the duty cycle.

Hardware requirements:

Arduino UNO:

The Arduino is a programmable #microcontroller, it's an open-source electronics proto-type platform. It interacts with the user by receiving input with the aid of sensors and provides the output employing LED, buzzer, etc.,

In order to know more about the Arduino UNO, refer to this article.

Potentiometer:

The name potentiometer is a combination of two words potential difference and metering. It is a three-terminal resistor that includes a sliding contact or rotary contact using which the resistance can be increased or decreased using the principle of a voltage divider.

The image above gives a clear understanding of how a potentiometer looks. The resistance can be increased or decreased by changing the position of the wiper by rotating the shaft. Since the resistance is proportional to the length of the track, it can be used as a variable resistance.

Breadboard:

A #breadboard is a flat piece of wood that is provided with holes that allow users to build a circuit including the components and connections without the need for soldering due to which it is reusable and finds its best usage for the students who are new to build circuits. The holes in any horizontal line will be in series whereas the vertical holes remain at an equipotential state. There are different sizes of breadboards available in the market which include "full size", "half-size" and, "mini size" breadboards.

LED:

LED is a semiconductor light source that emits light when a current passes through it. Electrons in the semiconductor combine with holes by passing through the gap which inturns release energy in the form of photons.

Resistor:

A Resistor as the name signifies opposes the flow of electrons. The Resistor is a passive element and has two terminals. They are used to monitor the current flow and also as voltage dividers. The #resistor that we would use in this circuit is a 220-ohm resistor and the color code for this resistor is Red, Red, Brown & Gold.

Connecting wires:

Connecting wires are used to establish connections between different components in the circuit.

Software requirements:

Arduino IDE:

Arduino IDE - logo

The Arduino Integrated Development Environment (IDE) is a cross-platform application (for Windows, macOS, Linux) that is written in functions from C and C++. It is used to write and upload programs to Arduino compatible boards, but also, with the help of third-party cores, other vendor development boards.

Circuit connection:

Controlling PWM of LED using a potentiometer- circuit diagram

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Circuit connection involves the following steps:

The first and third pins of the potentiometer are connected to Vcc and ground respectively.
The second pin/signal pin of the potentiometer is connected to analog pin A0 of the Arduino.
The anode of the diode is connected to digital pin 9 of the Arduino through a 220-ohm resistor.
The cathode of the diode is connected to the ground of the Arduino.