1. What is a Red LED Voltage Calculator?

Definition: This calculator estimates the forward voltage drop across a red LED based on the supply voltage, current, and series resistance.

Purpose: It helps electronics hobbyists and engineers properly design LED circuits to ensure correct operation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( V_{led} \) — LED forward voltage (V)
• \( V_s \) — Supply voltage (V)
• \( I \) — Current through the circuit (A)
• \( R \) — Series resistance (Ω)

Explanation: The voltage drop across the resistor is subtracted from the supply voltage to determine the remaining voltage across the LED.

3. Importance of LED Voltage Calculation

Details: Proper voltage calculation ensures LEDs operate within their specified range, preventing burnout or insufficient brightness.

4. Using the Calculator

Tips: Enter the supply voltage in volts, current in amps (default 20mA = 0.02A), and resistance in ohms (default 220Ω). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's typical forward voltage for red LEDs?
A: Most red LEDs have forward voltage between 1.8V and 2.2V.

Q2: Why is current important in LED calculations?
A: LEDs are current-driven devices; too much current can destroy them, while too little makes them dim.

Q3: What if my calculated V_led is negative?
A: This means your resistor value is too high for the given supply voltage and current. Reduce resistance or increase supply voltage.

Q4: How do I choose the right resistor value?
A: Use Ohm's Law: \( R = \frac{V_s - V_{led}}{I} \)

Q5: Does this work for other LED colors?
A: Yes, but different colors have different typical forward voltages (e.g., blue/white LEDs ~3V).