1. What is LED Resistor Calculation?

LED resistor calculation determines the appropriate series resistor value needed to limit current through an LED, preventing damage while ensuring proper operation. This is based on Ohm's Law and the electrical characteristics of the LED.

2. How Does the Calculator Work?

The calculator uses the LED resistor formula:

Where:

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

Explanation: The formula calculates the voltage drop across the resistor (supply voltage minus LED voltage) and divides by the desired current to determine the required resistance.

3. Importance of Proper Resistor Selection

Details: Selecting the correct resistor is crucial for LED longevity and performance. Too small a resistor allows excessive current, damaging the LED. Too large a resistor results in dim operation.

4. Using the Calculator

Tips: Enter supply voltage in volts, LED forward voltage in volts, and desired LED current in amps. Typical LED currents range from 0.01A to 0.03A (10mA to 30mA) for standard LEDs.

5. Frequently Asked Questions (FAQ)

Q1: What happens if I don't use a resistor?
A: Without a current-limiting resistor, most LEDs will draw excessive current and burn out almost instantly.

Q2: What are typical LED voltage drops?
A: Red LEDs: 1.8-2.2V, Yellow/Green: 2.0-2.4V, Blue/White: 3.0-3.6V. Check manufacturer specifications for exact values.

Q3: Can I use the calculated resistor value directly?
A: Use the nearest standard resistor value. For safety, choose the next higher standard value if the calculated value isn't available.

Q4: What about resistor power rating?
A: Calculate power dissipation: P = I² × R. Choose a resistor with power rating at least 1.5 times the calculated power.

Q5: Can multiple LEDs share one resistor?
A: Only if connected in series. For parallel connections, each LED branch needs its own current-limiting resistor.