1. What is LED Voltage Drop?

The LED voltage drop (V_f) is the voltage required for an LED to turn on and emit light. Different colored LEDs have different forward voltage drops, typically ranging from 1.8V to 3.3V.

2. How Does the Calculator Work?

The calculator uses these equations:

Where:

• \( R \) — Resistor value (Ω)
• \( V_s \) — Supply voltage (V)
• \( V_f \) — LED forward voltage (V)
• \( I \) — Current through LED (A)
• \( P \) — Power dissipated in resistor (W)

Explanation: The resistor limits current to protect the LED, and the power calculation ensures the resistor can handle the heat generated.

3. Importance of Proper Resistor Selection

Details: Choosing the correct resistor prevents LED damage from excessive current and ensures proper brightness. The power rating must be sufficient to avoid resistor overheating.

4. Using the Calculator

Tips: Enter supply voltage (V_s), LED forward voltage (V_f), and desired current (I). Typical LED current is 10-30mA (0.01-0.03A) 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 know my LED's forward voltage?
A: Check the LED datasheet. Typical values: Red=1.8-2.2V, Blue/White=3.0-3.3V, Green/Yellow=2.0-2.4V.

Q3: What happens if I don't use a resistor?
A: Most LEDs will burn out immediately when connected directly to a power source.

Q4: How do I choose the resistor power rating?
A: Select a resistor with at least double the calculated power dissipation for safety.

Q5: Can I connect multiple LEDs in series?
A: Yes, sum the forward voltages (V_f × number of LEDs) and use that in the calculation.