1. What is an LED Resistor Calculator?

Definition: This calculator determines the appropriate resistor value needed to safely operate an LED with a given power supply.

Purpose: It helps electronics hobbyists and engineers prevent LED damage by limiting current flow through the circuit.

2. How Does the Calculator Work?

The calculator uses Ohm's Law formula:

Where:

• \( R \) — Resistor value (ohms)
• \( V_{supply} \) — Power supply voltage (volts)
• \( V_{led} \) — LED forward voltage (volts)
• \( I_{led} \) — Desired LED current (amps)

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

3. Importance of Proper LED Current Limiting

Details: LEDs require precise current control. Too much current can burn out the LED, while too little results in dim operation.

4. Using the Calculator

Tips: Enter the supply voltage, LED voltage (default 3.3V for typical LEDs), and desired current (default 20mA). All values must be > 0 and supply voltage > LED voltage.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical LED forward voltage?
A: Red LEDs ~1.8-2.2V, Blue/White ~3.0-3.6V. Check your LED's datasheet for exact values.

Q2: How do I choose the LED current?
A: Standard LEDs typically use 20mA (0.02A), but check your LED's maximum rating.

Q3: What if my calculated resistor isn't a standard value?
A: Use the next higher standard resistor value for safety.

Q4: How do I calculate resistor power rating?
A: \( P = I^2 \times R \). Choose a resistor with at least double the calculated power.

Q5: Can I use this for multiple LEDs?
A: For series LEDs, sum their voltages. For parallel, calculate each branch separately.