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Schematic

Open project folder on GitHub

This example shows an NPN transistor used as a low-side switch to drive an LED load.

Circuit Summary

A base resistor controls the NPN transistor, sinking current from an LED and series resistor tied to VCC.

Expected Behavior

  • LED current rises sharply once V_BE exceeds ~0.7 V.
  • Collector voltage drops near ground when the transistor saturates.

How To Run

  1. Open Actuator-NPN-switch-LED.kicad_sch in KiCad.
  2. Click Simulate and run the configured analyses.
  3. Add probes to the key nodes to view the expected behavior.

Notes

  • Compare base current to LED current to see saturation margin.