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 select the correct current-limiting resistor for LED circuits.

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)
• \( I \) — Desired current through LED (amperes)

Explanation: The resistor value is calculated by dividing the voltage drop across the resistor by the desired current.

3. Importance of LED Current Limiting

Details: LEDs require precise current control to prevent damage and ensure proper brightness. Too much current can destroy an LED, while too little makes it dim.

4. Using the Calculator

Tips: Enter the supply voltage, LED voltage (typically 1.8-3.3V for most LEDs), and desired current (20mA or 0.02A is common for standard LEDs).

5. Frequently Asked Questions (FAQ)

Q1: What if my calculated resistor isn't a standard value?
A: Use the next higher standard resistor value to ensure safe current levels.

Q2: How do I find my LED's voltage?
A: Check the LED datasheet or use 2V for red, 3.3V for blue/white as general guidelines.

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: What happens if supply voltage equals LED voltage?
A: The calculation would require 0Ω resistor, which isn't safe. Always ensure supply voltage is higher than LED voltage.

Q5: How do I calculate resistor power rating?
A: Power = I² × R. Choose a resistor with wattage rating higher than this calculated value.