LED and current-limiting resistor
Choose a supply, LED and resistor. Compare forward voltage, current and power to see why an LED needs a series resistor.
Read the lesson →INTERACTIVE ELECTRONICS LEARNING
Learn circuit simulation by building real examples
Use resistor.dev to assemble a circuit, see voltages and currents, run a transient simulation, inspect the oscilloscope and understand why the result changes.
Start the circuit simulatorStart with the fundamentals
RC charging and timing
Charge a capacitor through a resistor and use the oscilloscope to observe the time constant and the exponential voltage curve.
Read the lesson →Diodes and rectifiers
Explore diode polarity, forward drop and half-wave rectification. Compare the educational model with SPICE accuracy mode.
Read the lesson →Transistor switch
Use an NPN transistor to control an LED load, then measure base and collector current.
Read the lesson →ESP32 GPIO safety
Keep GPIO voltage and current within board limits. Learn when an LED resistor is enough and when a transistor driver is needed.
Read the lesson →Battery and incandescent lamp
Observe battery voltage sag, filament heating and the inrush current at switch-on.
Read the lesson →FROM SCHEMATIC TO MEASUREMENT
See what a circuit is doing
Measure voltage, current and power at a selected component. Use the four-channel oscilloscope for time-dependent signals, or open Engineering tools for a multimeter, current clamp, protocol decoding, thermal estimates and tolerance analysis.
The circuit editor runs in the browser. SPICE mode uses ngspice compiled to WebAssembly, while the fast educational mode is designed for immediate experimentation.
A REPEATABLE WORKFLOW
Build, simulate, measure, improve
- Place components. Start from a simple source and load, then connect only the intended electrical nodes.
- Set real constraints. Add component ratings, an internal resistance or a SPICE model when the ideal model is not enough.
- Run and inspect. Read the values, look at the oscilloscope and check overload warnings.
- Prepare hardware. Use the BOM, breadboard view and KiCad netlist as a starting point, then verify the data sheet before powering real hardware.
Simulation is a learning and design aid
Results depend on the selected model and component data. The educational engine simplifies many physical effects. Confirm limits, pinouts and safety requirements against manufacturer documentation and real measurements before building hardware.
Open resistor.dev