How to Use LED: Two Pin (yello) - Long Pins: Examples, Pinouts, and Specs

A yellow light-emitting diode (LED) is a semiconductor device that emits yellow light when an electric current flows through it. This specific LED features two long pins, making it easy to integrate into breadboards and circuit boards. It is commonly used for visual indicators, such as power or status signals, in electronic circuits. Its bright yellow light is ideal for applications requiring clear visibility.

• Power or status indicators in electronic devices
• Visual feedback in microcontroller projects
• Decorative lighting in DIY projects
• Signal indicators in control panels
• Educational electronics kits and prototyping

Below are the key technical details for the yellow two-pin LED:

1. Identify the Pins: The longer pin is the anode (+), and the shorter pin is the cathode (-).
2. Connect a Resistor: Always use a current-limiting resistor in series with the LED to prevent damage. Calculate the resistor value using Ohm's Law: [ R = \frac{V_{supply} - V_f}{I_f} ]
   • (V_{supply}): Supply voltage
   • (V_f): Forward voltage of the LED (2.0V to 2.2V)
   • (I_f): Desired forward current (typically 20mA)
3. Insert into Circuit: Place the LED and resistor in the circuit, ensuring correct polarity.
4. Power the Circuit: Apply power to the circuit. The LED should emit a yellow light.

Below is an example of how to connect the yellow LED to an Arduino UNO and control it using code:

• Connect the anode (long pin) of the LED to a digital pin on the Arduino (e.g., pin 13) through a 220Ω resistor.
• Connect the cathode (short pin) to the Arduino's GND.

// This code blinks a yellow LED connected to pin 13 of the Arduino UNO.

// Define the pin where the LED is connected
const int ledPin = 13;

void setup() {
  // Set the LED pin as an output
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Turn the LED on
  digitalWrite(ledPin, HIGH);
  delay(1000); // Wait for 1 second
  
  // Turn the LED off
  digitalWrite(ledPin, LOW);
  delay(1000); // Wait for 1 second
}

• Use a Resistor: Never connect the LED directly to a power source without a resistor, as this can cause it to burn out.
• Polarity Matters: Ensure the anode and cathode are connected correctly; reversing the polarity will prevent the LED from lighting up.
• Avoid Overcurrent: Do not exceed the maximum forward current (30mA) to avoid damaging the LED.
• Heat Management: In high-power applications, ensure proper heat dissipation to maintain LED longevity.

1. LED Does Not Light Up

   • Cause: Incorrect polarity.
   • Solution: Verify that the anode is connected to the positive terminal and the cathode to ground.
   • Cause: Missing or incorrect resistor value.
   • Solution: Ensure a current-limiting resistor is used and properly calculated.

2. LED is Dim

   • Cause: Insufficient current.
   • Solution: Check the resistor value and ensure the supply voltage is adequate.

3. LED Burns Out Quickly

   • Cause: Excessive current.
   • Solution: Use a resistor with a higher resistance value to limit the current.

4. LED Flickers

   • Cause: Unstable power supply or loose connections.
   • Solution: Check the power source and ensure all connections are secure.

Q: Can I use this LED with a 3.3V or 5V power supply?
A: Yes, but you must use an appropriate resistor to limit the current. For a 5V supply, a 150Ω to 220Ω resistor is recommended. For a 3.3V supply, a 100Ω resistor is suitable.

Q: Can I connect multiple LEDs in series?
A: Yes, but ensure the total forward voltage of the LEDs does not exceed the supply voltage. Use a resistor to limit the current.

Q: How do I calculate the resistor value for multiple LEDs in parallel?
A: Each LED should have its own resistor. Calculate the resistor value for each LED individually based on the supply voltage and forward voltage.

Q: What happens if I reverse the polarity?
A: The LED will not light up, but it will not be damaged unless excessive reverse voltage is applied.

By following this documentation, you can effectively use the yellow two-pin LED in your electronic projects!