LED

### Understanding LEDs: A Beginner’s Lesson by Astrid and Gear

**Setting:** Astrid and Gear are in their cozy workshop, filled with various gadgets and mechanical components. Astrid has just taken out an assortment of LEDs from her Adventure Kit.

**Astrid:** “Gear, I’ve got all these different colored LEDs here. Can you explain how they work and what the differences are between them?”

**Gear:** “Of course, Astrid! LEDs come in a variety of colors, and each color is produced by using different materials in the semiconductor. Let’s dive into how different colored LEDs work and their

differences.”

**Astrid:** “Alright, let’s start with the basics. How do different colored LEDs produce different colors?”

**Gear:** “Great question! The color of an LED is determined by the energy gap of the semiconductor materials used. When electrons pass through the LED, they recombine with ‘holes’ and release energy in the form of light. The amount of energy released determines the color of the light.”

**Astrid:** “So, the materials inside the LED decide the color?”

**Gear:** “Exactly! For example, red LEDs typically use materials like aluminum gallium arsenide (AlGaAs), while blue LEDs use materials like indium gallium nitride (InGaN). Each material combination has a specific energy gap, which corresponds to a specific color of light.”

**Astrid:** “What are the differences between the colors in terms of their properties?”

**Gear:** “Different colored LEDs have different properties, such as forward voltage and brightness. Let’s go through some common colors and their characteristics.”

1. **Red LEDs:**

– **Gear:** “Red LEDs usually have a forward voltage of around 1.8 to 2.2 volts. They are very efficient and can be very bright. They are often used in indicators, traffic lights, and displays.”

– **Astrid:** “So, if I’m using a red LED, I need to make sure my circuit can provide around 2 volts?”

2. **Green LEDs:**

– **Gear:** “Green LEDs typically have a forward voltage of around 2.0 to 3.0 volts. They are also quite bright and are used in displays, indicators, and traffic lights.”

– **Astrid:** “Do green LEDs consume more power because of the higher voltage?”

3. **Blue LEDs:**

– **Gear:** “Blue LEDs usually have a forward voltage of around 3.0 to 3.5 volts. They are less efficient than red and green LEDs, but they are very bright. Blue LEDs are commonly used in displays, lighting, and indicators.”

– **Astrid:** “So, blue LEDs need more voltage and might drain my battery faster?”

4. **Yellow LEDs:**

– **Gear:** “Yellow LEDs have a forward voltage of around 2.0 to 2.4 volts. They are used in indicators and displays, similar to red and green LEDs.”

– **Astrid:** “Yellow LEDs are somewhere in the middle in terms of voltage requirements?”

5. **White LEDs:**

– **Gear:** “White LEDs are a bit different. They usually have a forward voltage of around 3.0 to 3.5 volts. White light is produced either by using a blue LED with a phosphor coating or by combining red,

green, and blue LEDs.”

– **Astrid:** “So, white LEDs can be used for general lighting because they provide a broad spectrum of light?”

**Astrid:** “This is really helpful, Gear. But can you show me a practical example of using different colored LEDs in a project?”

**Gear:** “Absolutely! Let’s create a simple project where we use multiple colored LEDs to create a colorful display.”

**Project: Creating a Colorful LED Display**

1. **Gather Materials:**

– **Gear:** “You’ll need the HERO board, several different colored LEDs (red, green, blue, yellow), and appropriate resistors for each LED.”

2. **Connect the LEDs:**

– **Gear:** “Connect each LED to a different digital pin on the HERO board. For example, connect the red LED to pin 2, the green LED to pin

3, the blue LED to pin 4, and the yellow LED to pin 5. Remember to connect a resistor in series with each LED to limit the current.”

– **Astrid:** “Got it. All the LEDs are connected with resistors.”

3. **Write the Code:**

– **Gear:** “Open the Arduino IDE and write this code to create a simple light sequence:”

“`cpp

void setup() {

pinMode(2, OUTPUT); // Red LED

pinMode(3, OUTPUT); // Green LED

pinMode(4, OUTPUT); // Blue LED

pinMode(5, OUTPUT); // Yellow LED

}

void loop() {

digitalWrite(2, HIGH); // Turn on red LED

delay(500); // Wait for 0.5 second

digitalWrite(2, LOW); // Turn off red LED

digitalWrite(3, HIGH); // Turn on green LED

delay(500); // Wait for 0.5 second

digitalWrite(3, LOW); // Turn off green LED

digitalWrite(4, HIGH); // Turn on blue LED

delay(500); // Wait for 0.5 second

digitalWrite(4, LOW); // Turn off blue LED

digitalWrite(5, HIGH); // Turn on yellow LED

delay(500); // Wait for 0.5 second

digitalWrite(5, LOW); // Turn off yellow LED

}

“`

4. **Upload the Code:**

– **Gear:** “Connect the HERO board to your computer using the USB cable. Select the correct board and port in the Arduino IDE, then click the upload button.”

5. **Test the Project:**

– **Gear:** “Once the code is uploaded, the LEDs should light up in sequence, creating a colorful display.”

**Astrid:** “Wow, it works! The LEDs look amazing. This is so cool, Gear. Thanks for explaining everything.”

**Gear:** “You’re welcome, Astrid. Different colored LEDs can add a lot of visual interest to your projects. Keep experimenting and finding new ways to use them!”

**Astrid:** “I will, Gear. This is just the beginning of my journey with LEDs!”