Frequently Asked Questions
Why does an LED need a resistor?
LEDs have no built-in current limiting. Without a resistor, excessive current flows through the LED, causing damage. The resistor limits current to a safe operating level.
How do I find the LED forward voltage (Vf)?
Check the LED's datasheet. Typical values are around 2V for red LEDs and 3.0-3.5V for blue or white LEDs.
How do I calculate resistors for multiple LEDs?
For series connections, sum all LED forward voltages. For parallel connections, use a separate resistor for each LED branch to ensure equal current distribution.
2026 physical constants