Green LED Current-Limited Indicator

Application

This circuit uses the Green LED as a simple DC panel indicator powered from a 5 V rail. It is set up as an interactive operating point example, so value changes update the steady-state probe table and LED brightness without running a time-domain waveform.

Design Context

A series resistor is the standard way to operate an indicator LED from a voltage source. The resistor limits current while the LED diode sets a forward voltage drop. Interactive operating point simulation is a good fit for this circuit because the useful behavior is the static relationship between supply voltage, resistor value, LED forward voltage, and LED current.

Expected Behavior

Current flows from the 5 V source through R1 and the Green LED to ground. The table should show the LED node voltage and branch current for the current component values. As the current changes, the Green LED dynamic symbol should brighten or dim to match the new operating point.

Key Values

• Simulation mode: interactive operating point
• Supply: 5 V DC
• Current-limiting resistor: 1 kOhm
• Expected behavior: forward-biased LED with modest indicator current

Suggested Experiments

• Change R1 to 330 ohm or 2.2 kOhm and compare the live LED current in the table.
• Lower the source voltage to find where the LED no longer visibly turns on.
• Reverse the LED and observe that current falls near zero.

Featured Component

The Green LED is a generic two-pin indicator diode with anode and cathode pins plus a dynamic symbol that brightens when simulated forward current is present.