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

The Two Pin Red LED is a light-emitting diode that emits red light when powered. It features two pins: a longer pin (anode) and a shorter pin (cathode), making it easy to identify polarity. The long pins are particularly useful for breadboard prototyping or soldering in permanent circuits. This LED is widely used in electronics for visual indicators, status lights, and decorative lighting.

• Power and status indicators in electronic devices
• DIY electronics and prototyping
• Signal and warning lights
• Decorative and ambient lighting

Below are the key technical details for the Two Pin Red LED:

The Two Pin Red LED has the following pin configuration:

1. Identify the Pins: The longer pin is the anode (+), and the shorter pin is the cathode (-).

2. Connect to Power:

   • Connect the anode to the positive terminal of the power source.
   • Connect the cathode to the negative terminal or ground.

3. Use a Resistor: Always use a current-limiting resistor in series with the LED to prevent damage. The resistor value can be calculated using Ohm's Law: [ R = \frac{V_{supply} - V_f}{I_f} ] Where:

   • (V_{supply}) is the supply voltage.
   • (V_f) is the forward voltage of the LED (1.8V to 2.2V).
   • (I_f) is the desired forward current (typically 20mA).

   For example, with a 5V supply: [ R = \frac{5V - 2V}{0.02A} = 150\Omega ]

4. Insert into Circuit: Place the LED and resistor in the circuit, ensuring correct polarity.

The Two Pin Red LED can be easily connected to an Arduino UNO for control. Below is an example of how to blink the LED:

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

// LED Blink Example for Two Pin Red LED
// Connect the anode (long pin) to pin 13 through a 220Ω resistor
// Connect the cathode (short pin) to GND

const int ledPin = 13; // Pin connected to the LED

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

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

• Polarity: LEDs are polarized components. Reversing the polarity can prevent the LED from lighting up or damage it.
• Current Limiting: Always use a resistor to limit the current through the LED.
• Voltage Range: Ensure the supply voltage does not exceed the LED's forward voltage without a resistor.

1. LED Does Not Light Up

   • Cause: Incorrect polarity.

   • Solution: Ensure the anode is connected to the positive terminal and the cathode to ground.

   • Cause: No current-limiting resistor or incorrect resistor value.

   • Solution: Use a resistor with the correct value (e.g., 150Ω for a 5V supply).

2. LED is Dim

   • Cause: Insufficient current.
   • Solution: Check the resistor value and ensure it allows enough current (e.g., 20mA).

3. LED Burns Out

   • Cause: Excessive current due to no resistor or a low-value resistor.
   • Solution: Always use a resistor to limit the current.

4. Flickering LED

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

Q: Can I connect the LED directly to a 3.3V or 5V power source?
A: No, you must use a current-limiting resistor to prevent excessive current from damaging the LED.

Q: What happens if I reverse the polarity?
A: The LED will not light up. In most cases, it will not be damaged, but prolonged reverse voltage may harm the LED.

Q: Can I use this LED with a PWM signal?
A: Yes, the LED can be dimmed or controlled using a PWM signal from a microcontroller like an Arduino.

Q: How do I calculate the resistor value for different supply voltages?
A: Use the formula (R = \frac{V_{supply} - V_f}{I_f}), where (V_f) is the forward voltage and (I_f) is the desired current.

This concludes the documentation for the Two Pin Red LED.