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 drop (volts)
• \( I_{led} \) — Desired LED current (amps)

Explanation: The resistor value is calculated by subtracting the LED 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 (typically 1.8-3.3V), and desired current (usually 10-30mA). All values must be positive and supply voltage must exceed LED voltage.

5. Frequently Asked Questions (FAQ)

Q1: Why do we subtract LED voltage from supply voltage?
A: The resistor only needs to drop the excess voltage that isn't used by the LED.

Q2: What's a typical LED current?
A: Most standard LEDs operate at 20mA (0.02A), but check your LED's datasheet for exact values.

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 find my LED's forward voltage?
A: Check the datasheet or assume 2V for red, 3.3V for blue/white LEDs if unknown.

Q5: What about resistor power rating?
A: Calculate power with P = I²R and choose a resistor with at least twice that rating.