5mm Blue LED
A higher forward-voltage LED that needs more supply headroom than red or green — a common gotcha when swapping LED colors in an existing circuit.
How this component works
An LED is a diode built from a semiconductor that emits photons when electrons cross its junction. Like any diode, it only conducts in one direction and has a forward voltage drop — but that drop depends on the LED's color, since color corresponds to the semiconductor's bandgap energy (red and infrared LEDs have the lowest forward voltage, blue and white the highest).
Because an LED's resistance drops sharply once it starts conducting, it must always be paired with a current-limiting resistor — connecting one directly across a supply voltage higher than its forward voltage will destroy it almost instantly.
CircuitForge lets you set the forward voltage directly, which is the one parameter that changes between LED colors in the simulation.
Common Use Cases
- Status indicator on circuits with at least 5V of supply headroom
- Component in an RGB mixing demonstration alongside red and green LEDs
- Demonstrating why forward voltage matters when swapping components in a fixed-resistor circuit
Frequently Asked Questions
Can I swap a red LED for a blue one with the same resistor?
Only if your supply voltage has enough headroom above blue's ~3.2V forward voltage — on a 3V coin-cell circuit sized for a 2V red LED, a blue LED may barely light or not turn on at all. Recompute the resistor for the new forward voltage.
Why do blue LEDs often seem dimmer at the same current?
Perceived brightness depends on both output power and the eye's sensitivity curve, which peaks in green — so equal electrical power doesn't mean equal perceived brightness across colors.