1. What is LED Resistor Calculation?

The LED resistor calculation determines the appropriate resistor value needed to safely 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 adapted for LED circuits:

Where:

• \( R \) — Resistor value in ohms (Ω)
• \( V_s \) — Supply voltage in volts (V)
• \( V_{led} \) — LED forward voltage drop (V)
• \( I \) — Desired current through LED in amperes (A)

Explanation: The resistor must drop the difference between supply voltage and LED voltage at the desired current.

3. Importance of Proper Resistor Selection

Details: Choosing the correct resistor is critical for LED longevity and brightness control. Too small a resistor allows excessive current that can destroy the LED, while too large a resistor makes the LED dim or prevents it from lighting.

4. Using the Calculator

Tips:

• Typical LED voltages: 1.8-3.3V for red/yellow, 3.0-3.6V for blue/white/green
• Common LED currents: 10-30mA (0.01-0.03A) for standard LEDs
• Supply voltage must be greater than LED voltage
• Choose a resistor with power rating higher than calculated dissipation

5. Frequently Asked Questions (FAQ)

Q1: What if my supply voltage equals LED voltage?
A: The calculation gives R=0, which means you need a current regulator instead of a simple resistor.

Q2: Can I use this for multiple LEDs?
A: For series connection, sum the LED voltages. For parallel, calculate resistors separately for each branch.

Q3: Why is power dissipation important?
A: Resistors must be rated for the power they'll dissipate (typically 1/4W, 1/2W, or 1W for LED circuits).

Q4: What about LED brightness?
A: Brightness is proportional to current, but stay within the LED's maximum rating (check datasheet).

Q5: How precise do resistor values need to be?
A: Standard 5% tolerance resistors are usually fine, but high-brightness applications may need 1% tolerance.