How to Use 3mm LED Red: Examples, Pinouts, and Specs

The 3mm Red LED (Manufacturer: Bojack, Part ID: 20mA/2-2.2V) is a compact, efficient, and reliable light-emitting diode that emits red light when powered. It is widely used in electronic circuits for visual indicators, status displays, and decorative lighting. Its small size and low power consumption make it ideal for applications in consumer electronics, DIY projects, and embedded systems.

• Power and status indicators in electronic devices
• Signal and warning lights
• DIY electronics and hobby projects
• Displays and decorative lighting
• Embedded systems and microcontroller-based circuits

Below are the key technical details for the Bojack 3mm Red LED:

The 3mm Red LED has two pins: the Anode (positive) and the Cathode (negative). The longer pin is the Anode, and the shorter pin is the Cathode.

1. Determine the Resistor Value: To prevent damage to the LED, always use a current-limiting resistor in series with the LED. The resistor value can be calculated 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 or 0.02A)

   For example, if (V_{supply} = 5V): [ R = \frac{5V - 2.2V}{0.02A} = 140\Omega ] Use the nearest standard resistor value (e.g., 150Ω).

2. Connect the LED:

   • Connect the Anode to the positive terminal of the power supply through the resistor.
   • Connect the Cathode to the ground or negative terminal.

3. Power the Circuit: Apply the appropriate voltage to the circuit. The LED will emit red light when powered correctly.

• Polarity: LEDs are polarized components. Reversing the polarity may damage the LED.
• Current Limiting: Always use a resistor to limit the current through the LED to prevent overheating or failure.
• Brightness Control: Use a lower current (e.g., 10mA) for dimmer light or a pulse-width modulation (PWM) signal for adjustable brightness.
• Operating Conditions: Ensure the LED operates within its specified voltage and current ratings.

Below is an example of how to connect and control the 3mm Red LED using an Arduino UNO:

• Connect the Anode of the LED to Arduino pin 9 through a 220Ω resistor.
• Connect the Cathode to the Arduino's GND pin.

// Example code to blink a 3mm Red LED connected to pin 9 of Arduino UNO

const int ledPin = 9; // Define the pin connected to the LED

void setup() {
  pinMode(ledPin, OUTPUT); // Set pin 9 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
}

1. LED Does Not Light Up:

   • Cause: Incorrect polarity.

   • Solution: Ensure the Anode is connected to the positive terminal and the Cathode to the 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 the current is within the recommended range (20mA).

3. LED Overheats or Burns Out:

   • Cause: Excessive current.
   • Solution: Use a proper current-limiting resistor to prevent overcurrent.

4. LED Flickers:

   • Cause: Unstable power supply or loose connections.
   • Solution: Ensure a stable power source and secure all connections.

Q1: Can I connect the LED directly to a 3.3V or 5V power supply?
A1: No, you must use a current-limiting resistor to prevent excessive current from damaging the LED.

Q2: Can I use the 3mm Red LED with a PWM signal?
A2: Yes, the LED can be dimmed or controlled using a PWM signal from a microcontroller like an Arduino.

Q3: What happens if I reverse the polarity of the LED?
A3: The LED will not light up, and prolonged reverse voltage may damage it.

Q4: Can I use this LED for high-power applications?
A4: No, this LED is designed for low-power applications with a maximum current of 20mA.

By following this documentation, you can effectively use the Bojack 3mm Red LED in your projects while ensuring optimal performance and longevity.