1. What is LED Resistor Calculation?

LED resistor calculation determines the appropriate resistance value needed to limit current through an LED when connected to a power supply. This prevents the LED from burning out due to excessive current.

2. How Does the Calculator Work?

The calculator uses Ohm's Law formula:

Where:

• \( R \) — Resistor value in ohms (Ω)
• \( V_{supply} \) — Power supply voltage in volts (V)
• \( V_{led} \) — LED forward voltage drop in volts (V)
• \( I_{led} \) — Desired LED current in amperes (A)

Explanation: The formula calculates the voltage drop across the resistor (supply voltage minus LED voltage) divided by the desired current to determine the required resistance.

3. Importance of Proper Resistor Selection

Details: Correct resistor selection is crucial for LED longevity and performance. Too little resistance allows excessive current, damaging the LED. Too much resistance results in dim operation.

4. Using the Calculator

Tips: Enter supply voltage in volts, LED forward voltage in volts, and desired LED current in amps. Ensure supply voltage is greater than LED voltage for proper operation.

5. Frequently Asked Questions (FAQ)

Q1: What is typical LED forward voltage?
A: Red LEDs: 1.8-2.2V, Green: 2.0-2.4V, Blue/White: 3.0-3.6V. Check manufacturer specifications for exact values.

Q2: What current do LEDs typically need?
A: Standard LEDs: 20mA (0.02A), High-power LEDs: 350mA-1A+. Always refer to LED datasheet for maximum ratings.

Q3: What if my calculated resistor isn't a standard value?
A: Use the next higher standard resistor value for safety, or combine resistors in series/parallel to achieve the desired value.

Q4: Can I use this for multiple LEDs?
A: For series connection, sum the LED voltages. For parallel, calculate each branch separately. Use separate resistors for each LED in parallel.

Q5: What about resistor power rating?
A: Calculate power using P = I² × R. Choose a resistor with power rating at least 1.5 times the calculated value for safety margin.