Your first circuit

Build a single-phase voltage divider and watch the scope.

1. Open the app

Visit www.numasim.com. You'll land in the editor with an empty canvas.

2. Place components

In the component palette on the left, type voltage source and drag the AC Voltage Source onto the canvas. Do the same for two Resistors (search resistor or just R).

Position them so the source is on the left, the two resistors stack to the right.

3. Wire them up

Click on a port (the small dot at the end of a component lead) to start a wire, then click on a destination port to complete it.

Wire the source's + port through the first resistor to the second resistor, and tie the bottom of the second resistor back to the source's - port.

4. Probe the divider node

Right-click the wire between the two resistors and pick Probe (or use the scope panel to add a trace by signal name). Name the signal v_mid.

5. Run

Click the Run button (the green triangle in the toolbar). The scope panel slides up from the bottom and v_mid streams in as the simulation ticks.

What just happened?

You authored a one-line netlist that the simulator solved using a trapezoidal integrator. The voltage at the midpoint should be half the source voltage when both resistors are equal — exactly what the scope shows.

Where to go from here

• Open a more complex sample from the gallery — e.g. the RLC series or PWM power control circuits.
• Read about observables to learn how the scope figures out what to plot.
• Try wrapping your circuit in a subsystem to run part of it at a finer time step.