1. What is the LED Resistor Calculator?

The LED Resistor Calculator helps determine the appropriate resistor value needed to safely operate an LED with a given power supply. It calculates both the resistance needed and the power dissipation in the resistor.

2. How Does the Calculator Work?

The calculator uses Ohm's Law and the LED resistor equation:

Where:

• \( R \) — Resistor value (Ω)
• \( V_s \) — Source voltage (V)
• \( V_{led} \) — LED forward voltage (V)
• \( I \) — LED current (A)

Explanation: The resistor value is calculated by subtracting the LED's forward voltage from the source voltage, then dividing by the desired current.

3. Importance of Proper Resistor Selection

Details: Choosing the correct resistor is crucial for LED operation. Too small a resistor can burn out the LED, while too large a resistor will make the LED dim or not light at all.

4. Using the Calculator

Tips: Enter source voltage in volts, LED forward voltage in volts (typically 1.8-3.3V for most LEDs), and desired current in amps (usually 0.01-0.03A for standard LEDs). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What if my calculated resistor value isn't standard?
A: Use the next higher standard resistor value to ensure you don't exceed the LED's current rating.

Q2: How do I know my LED's forward voltage?
A: Check the LED's datasheet. Typical values: red=1.8-2.2V, green/blue/white=3.0-3.6V.

Q3: What current should I use for my LED?
A: Standard LEDs typically use 20mA (0.02A), but check your specific LED's maximum rating.

Q4: Why is power dissipation important?
A: The resistor must be rated to handle the calculated power (typically use a resistor rated for at least twice the calculated power).

Q5: Can I connect multiple LEDs?
A: For multiple LEDs in series, sum their forward voltages. For parallel connections, calculate resistors for each LED separately.