1. What is an LED Resistor Calculator for Parallel Circuits?

Definition: This calculator determines the appropriate resistor value needed when connecting multiple LEDs in parallel to a power source.

Purpose: It helps electronics hobbyists and engineers properly limit current through parallel LEDs to prevent damage.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( R \) — Required resistance (Ω)
• \( V_s \) — Supply voltage (V)
• \( V_{led} \) — LED forward voltage drop (V)
• \( I_{led} \) — Desired LED current (A)
• \( N \) — Number of parallel LEDs

Explanation: The formula calculates the resistor value needed to limit the total current when multiple LEDs are connected in parallel.

3. Importance of Proper Resistor Calculation

Details: Correct resistor selection prevents LED burnout, ensures proper brightness, and maintains circuit stability.

4. Using the Calculator

Tips: Enter the power supply voltage, typical LED forward voltage (default 2.0V), desired current (default 20mA), and number of parallel LEDs. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the current multiplied by the number of LEDs?
A: In parallel circuits, current adds up - each LED draws its own current, so the resistor must handle the total current.

Q2: What's a typical LED forward voltage?
A: Most standard LEDs have 1.8-3.3V forward voltage (red ~2.0V, blue/white ~3.0V).

Q3: What current should I use for standard LEDs?
A: 20mA (0.02A) is common for indicator LEDs, but check your LED's datasheet for specifics.

Q4: Can I use this for different colored LEDs in parallel?
A: Not recommended - different colored LEDs typically have different forward voltages.

Q5: What resistor wattage should I use?
A: Calculate power (P=I²R) and choose a resistor with at least 2x the calculated wattage.